Lamellar Architecture Research Articles

Mechanical properties and fracture phenomena in 3D-printed helical cementitious architected materials under compression

The mechanical response and fracture behavior of two architected 3D-printed hardened cement paste (hcp) elements, ‘lamellar’ and ‘Bouligand’, were investigated under uniaxial compression. A lab-based X-ray microscope was used to characterize the post-fracture crack pattern. The mechanical properties and crack patterns were analyzed and compared to cast hcp. The role of materials architecture and 3D-printing-induced weak interfaces on the mechanical properties and fracture behavior are discussed. The pore architecture that inadvertently forms in the design of solid architected materials dictated the overall mechanical response and fracture behaviors in both 3D-printed architected materials. While no specific crack pattern or microcracking was observed in the cast element, lamellar architecture demonstrated a crack pattern following weak vertical interfaces. Bouligand architectures, on the other hand, exhibited a helical crack pattern with distributed interfacial microcracking aligned with the helical orientation of filaments. As a result, the bouligand architected elements showed a significant 40% increase in work-of-failure compared to cast counterparts. The enhanced energy absorption was obtained without sacrificing the strength and was attributed to higher fractured surface and microcracking, both of which follow the weak helical interfaces.

Concurrently boosted oxygen reduction/evolution electrocatalysis over highly loaded CoNi/onion-like carbon hybrid nanosheets

Balancing the bicatalytic activities and stabilities between oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a critical yet challenging task for exploring advanced rechargeable Zinc–air batteries (ZABs). Herein, a hybrid nanosheet catalyst with highly dispersed and densified metallic species is developed to boost the kinetics and stabilities of both ORR and OER concurrently. Through a progressive coordination and pyrolysis approach, we directly prepared highly conductive onion-like carbon (OLC) accommodating dense ORR-active CoNC species and enveloping high-loading OER-active CoNi-synergic structures within a porous lamellar architecture. The resultant CoNi/OLC nanosheet catalyst delivers better ORR and OER activities showcasing a smaller reversible oxygen electrode index (ΔE = Ej10 − E1/2) of 0.71 V, compared to state-of-the-art Pt/C-RuO2 catalysts (0.75 V), Co/amorphous carbon polyhedrons (0.80 V), NiO nanoparticles with higher Ni loading (1.00 V), and most CoNi-based bifunctional catalysts reported so far. The rechargeable ZAB assembled with the developed catalyst achieves a remarkable peak power density of 270.3 mW cm−2 (172 % of that achieved by Pt/C + RuO2) and ultrahigh cycling stability with a negligible increase in voltage gap after 800 h (110 mV increase after 200 h for a Pt/C + RuO2-based battery), standing the top level of those ever reported.

Simultaneous enhancement of strength and conductivity via self-assembled lamellar architecture

Simultaneous improvement of strength and conductivity is urgently demanded but challenging for bimetallic materials. Here we show by creating a self-assembled lamellar (SAL) architecture in W-Cu system, enhancement in strength and electrical conductivity is able to be achieved at the same time. The SAL architecture features alternately stacked Cu layers and W lamellae containing high-density dislocations. This unique layout not only enables predominant stress partitioning in the W phase, but also promotes hetero-deformation induced strengthening. In addition, the SAL architecture possesses strong crack-buffering effect and damage tolerance. Meanwhile, it provides continuous conducting channels for electrons and reduces interface scattering. As a result, a yield strength that doubles the value of the counterpart, an increased electrical conductivity, and a large plasticity were achieved simultaneously in the SAL W-Cu composite. This study proposes a flexible strategy of architecture design and an effective method for manufacturing bimetallic composites with excellent integrated properties.

Ablation behavior of high-entropy boride (Hf-Zr-Ta-Ti)B2 coating fabricated via supersonic atmospheric plasma spraying for carbon/carbon composites

Carbon/carbon (C/C) composites have the potential to fulfill the demands of thermal protection systems, whereas they are limited by oxygen susceptibility. Herein, a high-entropy boride (HEB) (Hf-Zr-Ta-Ti)B2 coating was deposited on C/C composites via supersonic atmospheric plasma spraying for ablation-resistant applications. The coated C/C composites showed a linear recession rate of 1.14 μm/s after oxyacetylene torch testing for 60 s. The good ablation resistance is attributed to the multicomponent synergy effect. The Ti-dominated liquid phase sealed defects, resulting in a dense oxide scale, and the Ta-induced lamellar architecture potentially improved its thermal shock resistance. This study demonstrates that HEBs with compositional breadth are effective in protecting C/C composites from ablation at ultra-high temperatures.

Towards high strengthening efficiency of equiaxed and platelet-shaped alumina reinforced zirconia ceramics with textured microstructure using DLP-based stereolithography

ZrO2–Al2O3 (ATZ) ceramics are attracting high interest in biomedical applications because of their desirable mechanical performance and biocompatibility. However, strength and toughness are mutually exclusive in structural ceramics. In this paper, based on digital light processing, novel textured ATZ ceramics with obvious crystallographic orientations were fabricated by incorporating Al2O3 platelets with a high aspect ratio and equiaxed particles into the ZrO2 matrix. The optimized fracture toughness of 16.9 ± 0.8 MPa m1/2 was achieved in the textured ATZ ceramic, which was about 67.3 % higher than non-textured ZrO2 ceramics, without sacrificing strength. The coupling toughening effects of macrolayer structure, equiaxed and platelet-shaped Al2O3 particles, and ZrO2 particles were responsible for the enhanced mechanical performance. The macroscale toughening of 3D-printed lamellar architecture led to effective energy dissipation. Additionally, the crack deflection and crack branching induced by dual-morphology Al2O3 particles, accompanied by the phase transformation of the ZrO2 matrix, were significant microscopic toughening mechanisms.

Functional significance of lamellar architecture in marine sponge fibers: Conditions for when splitting a cylindrical tube into an assembly of tubes will decrease its bending stiffness

Numerous ingenious engineering designs and devices have been the product of bio-inspiration. Bone, nacre, and other such stiff structural biological materials (SSBMs) are composites that contain mineral and organic materials interlaid together in layers. In nacre, this lamellar architecture is known to contribute to its fracture toughness, and has been investigated with the goal of discovering new engineering material design principles that can aid the development of synthetic composites that are both strong and tough. The skeletal anchor fibers (spicules) of Euplectella aspergillum (Ea.) also display a lamellar architecture; however, it was recently shown using fracture mechanics experiments and computations that the lamellar structure in them does not significantly contribute to their fracture toughness. An alternate hypothesis—the load carrying capacity (LCC) hypothesis—regarding the lamellar architecture’s functional significance in Ea. spicules is that it enhances the spicule’s strength, rather than its toughness. From an ecology perspective the LCC hypothesis is certainly plausible, since a higher strength would allow the spicules to more firmly anchor Ea. to the sea floor, which would be beneficial to it since it is a filter feeding animal. In this paper we present support for the LCC hypothesis from a solid and structural mechanics perspective, which, compared to the support from ecology, is far harder to identify but equally, if not more, compelling and valid. We found that when the spicule functions in a knotted configuration a reduced bending stiffness benefits its load carrying capacity and that sectioning a cylindrical tube into an assembly of co-axial tubes can reduce the tube’s bending stiffness for a wide class of materials that are consistent with the spicules’ axial symmetry. The mechanics theory developed in this paper has applications beyond providing support for the LCC hypothesis. For example, it makes apparent many design strategies for reducing the bending stiffness of large industrial cables (e.g., undersea optical data transmission cables) while maintaining their tensile strength, which has benefits towards the handling, storage, and transportation of such cables.

Lamellar Wood Sponge with Vertically Aligned Channels for Highly Efficient and Salt-Resistant Solar Desalination.

Solar-assisted interfacial evaporation is a promising approach for purifying and desalinating water. As a sustainable biomass material, wood has attracted increasing interest as an innovative substrate for solar desalination, owing to its intrinsic porous structure, high hydrophilicity, and low thermal conductivity. However, developing wood-based solar evaporators with high evaporation rates and excellent salt resistance still remains a significant challenge, owing to the absence of large pores with high interconnectivity in natural wood. Herein, by converting the honeycombed structure of natural wood into a lamellar architecture via structural engineering, we develop a flexible wood sponge with vertically aligned channels for efficient and salt-resistant solar desalination after surface coating with carbon nanotubes (CNTs). The special lamellar structure with an interlayer distance of 50-300 μm provides the wood sponge with faster water transport, lower thermal conductivity, and water evaporation enthalpy, thus achieving higher evaporation performances in comparison with the cellular structure of natural wood. Noteworthy, the vertically aligned channels of the wood sponge facilitate sufficient fluid convection and diffusion and enable efficient salt exchanges between the heating interface and the underlying bulk water, thus preventing salt accumulation on the surface. Benefiting from the distinctive lamellar structure, the developed wood-sponge evaporator exhibits exceptional salt resistance even in a hypersaline brine (20 wt %) during continuous 7-day desalination under 1 sun irradiation, with a high evaporation rate (1.38-1.43 kg m-2 h-1), outperforming most previously reported wood-based evaporators. The lamellar wood sponge may provide a promising strategy for desalinating high-salinity brines in an efficient manner.

Non-swelling oxidized graphene ribbon membrane for the effective separation of cesium and strontium from radioactive liquid waste

The interlayer swelling effect of graphene oxide (GO) membranes seriously hinders their applications in the precise nanofiltration, especially sieving cesium and strontium from radioactive liquid waste. Herein, a non-swelling membrane was successfully prepared via vacuum-filtering oxidized graphene ribbons (OGR), one kind of GO analogs. The unchanged interlayer spacing in OGR membrane (OGRM) were proved to originate from the unique two-section structure of OGR building blocks. Specifically, the low-defect aromatic plane in the central axis region of OGR resulted in the strong π‒π interaction, which prevented the further intercalation of water molecules at the nanoribbon edges and locked the whole lamellar architecture, hence inhibiting the peripheral expansion of OGR. By virtue of fixed nanochannels of OGRM, an ideal separation of Cs+ and Sr2+ was realized in the multicomponent acidic waste (pH ∼2.3), and the separation factors relative to UO22+ were fCs/UO2 = 6319 and fSr/UO2 = 2705, respectively. Meanwhile, OGRM showed a fast water flux of 12.10 L m−2 h−1, 15% higher than that of graphene oxide membrane (GOM). In addition to the special interlayer nanochannels, an in-depth investigation revealed that oxygenated groups also played an important role in the ion selectivity of OGRM. This preparation strategy of the non-swelling membrane is crucial to overcome the inherent paradox between the optimal selectivity and low flux, and our findings are very useful to remediate radioactive pollution and ensure water security.

Superior strength-plasticity synergy in a heterogeneous lamellar Ti2AlC/TiAl composite with unique interfacial microstructure

Improving the plasticity of TiAl alloys at room temperature has been a longstanding challenge for the development of next-generation aerospace engines. By adopting the nacre-like architecture design strategy, we have obtained a novel heterogeneous lamellar Ti2AlC/TiAl composite with superior strength-plasticity synergy, i.e., compressive strength of ∼2065 MPa and fracture strain of ∼27%. A combination of micropillar compression and large-scale atomistic simulation has revealed that the superior strength-plasticity synergy is attributed to the collaboration of Ti2AlC reinforcement, lamellar architecture and heterogeneous interface. More specifically, multiple deformation modes in Ti2AlC, i.e., basal-plane dislocations, atomic-scale ripples and kink bands, could be activated during the compression, thus promoting the plastic deformation capability of composite. Meanwhile, the lamellar architecture could not only induce significant stress redistribution and crack deflection between Ti2AlC and TiAl, but also generate high-density SFs and DTs interactions in TiAl, leading to an improved strength and strain hardening ability. In addition, profuse unique Ti2AlC(11¯03¯)/TiAl(111) interfaces in the composite could dramatically contribute to the strength and plasticity due to the interface-mediated dislocation nucleation and obstruction mechanisms. These findings offer a promising paradigm for tailoring microstructure of TiAl matrix composites with extraordinary strength and plasticity at ambient temperature.

Highly robust separation for aqueous oils enabled by balsa wood-based cellulose aerogel with intrinsic superior hydrophilicity

Owing to the strong adsorption capacity, cellulose aerogel has emerged as a promising material in the field of oil–water separation. In this study, we have taken advantage of the inherent superior hydrophilicity of balsa wood-based cellulose aerogel for the separation of various aqueous oils. A facile approach to preserve inherent hydrophilic cellulose nanofibers was achieved by removing lignin and hemicellulose fractions from natural wood, resulting in flexible cellulose aerogel with lamellar architecture. As a result, the separation efficiency of cellulose aerogel can achieve 99.97% for immiscible aqueous oils, and 98.45% even for water-in-oil emulsions. Moreover, the as-prepared cellulose aerogel exhibits remarkable mechanical properties, with stress decay of 7% after 60 compression cycles making it recycle feasible. When exposed to several complex environments including acid, alkaline and salt for a long time, the cellulose aerogel remains stable superoleophobicity with underwater oil contact angle of 153.2 ± 1.2°. Given the low operating cost, high separation efficiency and durability and stability of cellulose aerogel, this work provides a promising material for aqueous oils purification.

A multifaceted biomimetic periosteum with a lamellar architecture and osteogenic/angiogenic dual bioactivities.

An artificial periosteum has emerged as an encouraging candidate for bone defect repair. Currently, it remains a great challenge to develop a multifaceted biomimetic periosteum integrating multifunctional features of bioactivities and unique mechanical properties. Here, we successfully fabricated an artificial periosteum (AP) composed of hierarchically assembled Mg-doped mineralized collagen microfibrils with a biomimetically rotated lamellar structure via a "multiscale cascade regulation" strategy combining multiple techniques such as molecular self-assembly, electrospinning, and pressure-driven fusion from molecular to macroscopic levels. The AP has excellent mechanical properties with an ultimate strength and a tensile modulus of 15.9 MPa and 1.1 GPa, respectively. The involvement of Mg-doped nano-hydroxyapatite endowed the AP with good osteogenic and angiogenic activities to promote osteogenic differentiation of bone marrow mesenchymal stem cells and human umbilical vein endothelial cell differentiation into capillary-like structures in vitro. In addition, the results of in vivo evaluations in a rat cranial bone defect model including micro-CT morphology, histological staining, and immunohistochemical analysis showed that Mg-doped mineralized collagen-based AP (MgMC@AP) significantly facilitated cranial bone regeneration and fast vascularization. Our findings suggest that the AP mimicked the composition, lamellar structure, mechanical properties, and biological activities of natural periosteum/lamellae, showing great promise for bone tissue regeneration.

Efficient bifunctional 3D porous Co–N–C catalyst from spent Li–ion batteries and biomass for Zinc–Air batteries

The recovery of valuable metals from spent Li–ion batteries (LIBs) and their full utilization has become essential to support sustainable development. Herein, we designed an efficient 3D porous Co–N–C catalyst (Co@NCW–4) by combining the Co recovered from spent LIBs with biomass. Results illustrate Co@NCW–4 with the porous lamellar architecture utilizes the multiple channel structure for effective mass transfer and provides plentiful active sites, thus exhibiting great bifunctional oxygen electrocatalytic activity and stability. According to the data, Co@NCW–4 has the half–wave potential of 0.823 V vs RHE for oxygen reduction reaction, and an overpotential of 350 mV at 10 mA cm−2 for oxygen evolution reaction. The rechargeable Zn–air batteries assembled with the Co@NCW–4 exhibit excellent power density of 215 mW cm−2, and long–term stability better than RAZBs of benchmark Pt/C + RuO2. This research represents a general method for converting abundant biomass and spent LIBs into high environmentally preferable materials for energy–related applications.

Lightweight MXene-Based Hybrid Aerogels with Ultrabroadband Terahertz Absorption and Anisotropic Strain Sensitivity

MXene aerogels with a three-dimensional (3D) network structure have attracted increasing attention for lightweight electromagnetic wave absorbers. It is intriguing to expand their absorption band, i.e., to the booming terahertz (THz) region, and explore multifunctionality. Herein, we assemble MXene (Ti3C2Tx)-based hybrid aerogels into an aligned lamellar architecture using a bidirectional freezing technique. With air pore size and lamellar layer spacing comparable to THz wavelengths, high porosity of the aerogels allows nearly isotropic absorption of 99% and electromagnetic interference (EMI) shielding effectiveness with a remarkable value of 57.5 dB, in the ultrabroad bandwidth ranging from 0.5 to 3.0 THz. Simultaneous, strain-sensing response reflects the macroscopic anisotropy of the network structure of the aerogels. The improved sensitivity is measured for the out-of-lamellar layer plane under 0-30% strain. The corresponding long-term stability and durability persist over 120 stretching-releasing cycles. Our findings thus not only expand multiple functions of MXene in an anisotropic 3D macroscopic form but also clarify its nearly isotropic absorption in the THz band.

Effects of bridging fibers on the evolution of lamellar architecture during H2/H2O redox cycling of Fe-foams

Fe/Fe3O4 redox cycling via cyclic H2/H2O exposure at 800 °C is studied in lamellar Fe foams with 15 vol% fibers, created by freeze-casting. Fibers were integrated in the foams to mitigate densification during cycling by mechanically supporting neighboring lamellae, thus preventing buckling and sintering at contact points. Three fiber types are examined: short (0.1 mm) and long (1–2 mm) stainless-steel fibers, and long zirconia fibers. Long fibers bridge lamellae and have a marked effect on the architecture by increasing the initial interlamellar porosity (from < 60 to > 85%), with a corresponding decrease in foam shrinkage during initial reduction and sintering (from > 80 to < 55% volumetric loss). Though performance improves as compared to fiber-free foams, fiber effectiveness against damage decreases with cycling: after 10 redox cycles, porosity falls from 85 to 50% for foams with long fibers. One novel degradation mechanism is identified: fiber engulfment. This mechanism occurs over successive redox cycles, as material from the lamellae cyclically engulfs (as Fe3O4) and withdraws (as Fe) from the fibers, with a net transport from lamellae to fibers after each cycle. This cyclic coarsening mechanism alters foam architecture from bridged-lamellar (with evenly distributed porosity) to mixed lamellar/fibrous (with unevenly distributed porosity).

Nacre-Mimetic Hierarchical Architecture in Polyborosiloxane Composites for Synergistically Enhanced Impact Resistance and Ultra-Efficient Electromagnetic Interference Shielding.

Pervasive mechanical impact is growing requirement for advanced high-performance protective materials, while the electromagnetic interference (EMI) confers severe risk to human health and equipment operation. Bioinspired structural composites achieving outstanding safeguards against a single threat have been developed, whereas the synergistic implementation of impact/EMI coupling protection remains a challenge. This work proposes the concept of nacre-mimetic hierarchical composite duplicating the "brick-and-mortar" arrangement, which consists of freeze-drying constructed chitosan/MXene lamellar architecture skeleton embedded in a shear stiffening polyborosiloxane matrix. The resulting composite effectively attenuates the impact force of 85.9%-92.8% with extraordinary energy dissipation capacity, in the coordinative manner of strain-rate enhancement, structural densification, lamella dislocation and crack propagation. Attributed to the alternate laminated structure promoting the reflection loss of electromagnetic waves, it demonstrates an ultraefficient EMI shielding effectiveness of 47.2-71.8 dB within extremely low MXene loadings of 1.1-1.3 wt %. Furthermore, it serves favorably in impact monitoring and wireless alarm systems and accomplishes performance optimization through the combination of multiple biomimetic strategies. In conclusion, this function-integrated structural composite is shown to be a competitive candidate for sophisticated environments by resisting impact damage and EMI hazards.

Interfacial Charge-Modulated Multifunctional MoS2/Ti3C2Tx Penetrating Electrode for High-Efficiency Freshwater Production.

Freshwater production is critical in terms of solving the global water shortage. Aiming at improving freshwater production capability and ensuring its quality, an interfacial charge-modulated MoS2/Ti3C2Tx-modified carbon fiber (CF/MoS2/Ti3C2Tx) penetrating electrode is designed. To maximize the desalination and degradation efficiencies of CF/MoS2/Ti3C2Tx, a photocatalytic component is introduced into the membrane capacitive deionization (PMCDI) device. High desalination capability is derived from the lamellar architecture structure of MoS2/Ti3C2Tx. Meanwhile, excellent degradation performance is due to the formation of two photoelctrocatalytic activity centers, directionally generating singlet oxygen (1O2) and hydroxyl radical (•OH). The intercalated Cl- (desalination) as the electron transfer bridge optimizes the charge distribution of MoS2/Ti3C2Tx, reinforcing the photoelectrocatalytic activity (degradation). The formation of the electron-deficient (desalination) and electron-rich (regeneration) regions at the terminated O atom of Ti3C2Tx accelerate the generations of •OH and 1O2, respectively. In perspective, a mutual promotion process of desalination and degradation is achieved for high-efficiency production of high-quality freshwater.

Ice-Templated Fabrication of Porous Materials with Bioinspired Architecture and Functionality

ConspectusBiological porous materials, such as polar bear hair, wood, bamboo, and cuttlebone, exhibit outstanding thermal and mechanical properties due to their hierarchical architectures. Specifically, polar bears can retain thermal homeostasis in the extremely cold Arctic due to outstanding thermal insulation property of their porous hairs; wood and bamboo exhibit excellent mechanical strength, highly efficient water and nutrient transport capacity, and low density due to their hierarchically aligned porous architecture; cuttlebone can resist large hydrostatic pressure in the deep-sea environment due to its mechanically efficient porous structure with lamellar septa connected by asymmetrically S-shaped walls. Obviously, the hierarchical architecture is crucial for the excellent performance of biological porous materials. Inspired by these natural design motifs, bioinspired materials with hierarchical architectures have been extensively explored for various applications where excellent mechanical, thermal, and electric properties are highly demanded. As a controllable, versatile, scalable, and environmental-friendly process, ice templating (or freeze casting) represents an effective approach to mimicking the sophisticated architecture of biological materials in synthetic counterparts, which has attracted wide attention from research groups across the world.In recent years, we have conducted comprehensive studies on the mechanism of the ice-templating approach and provided a rich toolbox based on this technique to meet various manufacturing demands. We systematically studied the material assembly process and the heat and mass transfer mechanism of the ice-templating technology from the aspects of cold surface, temperature field design, and intrinsic properties of the building blocks. First, bidirectional freezing guided by dual temperature gradients was developed to generate a long-range nacre–mimetic lamellar architecture. Next, complex hierarchical lamellar architectures were constructed through freezing on engineered cold surfaces with either wettability gradient or grooved pattern. Additionally, the “freeze-spinning” technique was developed to realize continuous and large-scale fabrication of fibers with aligned porous architecture mimicking polar bear hair. Finally, the applicability of the unidirectional ice-templating technique was broadened from soluble to insoluble polymeric materials through the freezing of emulsion droplets. These techniques have been widely used to fabricate a series of porous materials with bioinspired architectures, which hold great potential in thermal regulation, liquid transport, and mechanical functions for wide applications in various fields. Finally, a concise summary of this Account, including latest development, future challenges and opportunities in the ice-templated fabrication of bioinspired porous materials will be provided. This Account provides guidance for the design and ice-templated fabrication of bioinspired porous materials with multiscale architecture and functionality, which are crucial for various engineering applications.

Evolution of lamellar architecture and microstructure during redox cycling of Fe-Co and Fe-Cu foams

The effects of alloying Fe with 25 at% Co or 30 at% Cu are studied in freeze-cast lamellar foams subjected to redox cycling under H 2 - and H 2 O-rich atmospheres at 800 ºC, relevant to metal-air batteries. In unalloyed Fe foams, redox cycling causes irreversible Kirkendall porosity growth within lamellae, leading to fracture and buckling in the lamellar architecture which in turn leads to foam densification after a few cycles. By contrast, Fe-25Co lamellae develop, upon oxidation, a pure Co core and a Fe 3 O 4 shell which decreases buckling and Kirkendall pore growth, thus slowing sintering and densification of the lamellar foams. After Fe 3 O 4 reduction, the Fe-rich shells and Co-rich cores of the lamellae re-homogenize by diffusion to the original single-phase Fe-25Co alloy, achieving a reversible microstructure upon a full redox cycle. After 10 cycles, average channel porosity (between lamellae) undergoes only a small decrease (from 62 % to 46 %), with minimal Kirkendall pore coarsening in the lamellae, consistent with strong sintering resistance in the Fe-25Co foams. The Fe-30Cu foams also display lamellae with Cu core and a Fe 3 O 4 shell structure after oxidation, since Cu, like Co, does not oxidize under steam. However, the lack of solubility of Cu in Fe prevents re-homogenization after Fe 3 O 4 reduction, so the resulting Cu-core / Fe-shell lamellae undergo severe sintering and densification upon subsequent redox cycling, with channel porosity reducing from 61 % to 9 % after just 5 cycles. For both systems, operando x-ray diffraction during redox cycling reveals that Cu, unlike Co, doubles the Fe oxidation rate, as compared to pure Fe foams. • Fe-25Co and Fe-30Cu metallic foams are created with high porosity and lamellar architecture. • Operando X-ray diffraction is used to track H 2 /H 2 O redox reactions in these foams at 850 °C. • Fe-25Co foams show excellent stability over 10 full redox cycles at 850 °C. • Fe-30Cu foams sinter during cycling, but Cu accelerates redox kinetics.

Advanced microscopic characterisation of multi-scale high-resolution mechanical behaviour of a nacre-inspired composite

A nacre-inspired composite with a lamellar architecture of polymethyl methacrylate (soft and tough phase) and alumina (stiff phase) was fabricated using a bidirectional freezing casting technique. The bulk fracture mechanics of the nacre-inspired composite has been reported along with detailed microstructural analysis. The mechanistic connection between microstructure and mechanical properties at the micro- and macro-scale was not fully understood. Herein we addressed this issue by quantifying phase-specific hardness, modulus, and residual stress at the micro-scale level and compared with the bulk mechanical response. A shear-lag model was applied to provide a quantitative understanding of the softening effects resulting from residual stress and the microstructure. Our findings demonstrated the potential of bioinspired synthetic architectures in providing a tuneable model system to investigate the underlying design principles of more complex hierarchical biological materials.

Antioxidant enzyme activity and pathophysiological responses in the freshwater walking catfish, Clarias batrachus Linn under sub-chronic and chronic exposures to the neonicotinoid, Thiamethoxam®.

The hydrophilic nature and resultant persistence of neonicotinoids in aquatic systems increase the exposure duration for non-target organisms. The sublethal toxicity of the neonicotinoid Thiamethoxam® spanning sub-chronic and chronic durations was investigated in Clarias batrachus, a non-target freshwater fish species. 96 h LC50 value of Thiamethoxam® on Clarias batrachus was 138.60 mg L-1. Pre-determined exposure concentrations of Thiamethoxam® (6.93 and 13.86 mg L-1) were used and effects were assessed at days 15, 30, and 45 exposure intervals. Biomarker effects were evaluated using antioxidant enzyme responses (CAT, SOD) neurotransmission (acetylcholinesterase activity), haematological and serum biochemistry changes (including haemoglobin content, total erythrocyte count, and serum albumin total leukocyte count, total serum protein, serum globulin, triglyceride, cholesterol, high-density lipoprotein, very low-density lipoprotein, low-density lipoprotein, phospholipid, and total serum glucose), histopathological alterations (gill and liver). Thiamethoxam®-exposed fish showed a marked reduction in haemoglobin content, total erythrocyte count, and serum albumin levels compared to control fish. Similarly, gill and liver antioxidant enzyme activity (CAT, SOD) and neurotransmission (acetylcholinesterase) also showed altered responses between sub-chronic exposure on day-15 and chronic responses on day-45. Histopathological observations in gill tissue revealed alterations ranging from vacuolation, hypertrophy, disruption of primary lamellar architecture, haemorrhage, the fusion of secondary lamella, and sloughing of outer epithelia. For liver tissue of exposed fish histopathological observations included increased sinusoidal spaces (ISS), necrosis of hepatocytes (NOH), nuclear degeneration (ND), disruption of architecture (DOA), macrophage infiltration of the central vein, vacuolation (V), hypertrophied hepatocytes, and haemorrhages. The gradients of toxic responses across exposure concentrations and depictions of impaired fish health with increasing thiamethoxam® exposure duration portend lowered physiological capacity for survival in the wild.