As electrons generated through substrate oxidation compete with electrodes, dissimilatory nitrate reduction to ammonium (DNRA), denitrification in bioelectrochemical systems in the presence of ...nitrate, and nitrate reduction through an electroactive biofilm (EAB) are unpredictable. We find that pathways of nitrate reduction are related to EAB thickness and that 76 ± 2 μm is the critical thickness of a biofilm at which both the inner and outer layers simultaneously include DNRA, leading to a maximum level of DNRA efficiency of 42%. Fractions of electrons flowing during nitrate reduction are relatively stable, but their distributions between DNRA and denitrification vary with biofilm thickness. Electrons prefer denitrification in an EAB that is 66 ± 2 μm, while DNRA reversely surpasses denitrification when the thickness increases in the range of 76 ± 2 to 210 ± 2 μm. Biofilm thickening enhances the DNRA of all biofilms close to solution, where nirK remains constant and nrfA is significantly upregulated. However, nrfA is downregulated in layers close to the electrode when the biofilm is thicker than 76 ± 2 μm. These findings reveal the spatially heterogeneous reduction of nitrate in thick EABs, highlighting the importance of biofilm thickness to the regulation of end products of nitrate reduction.
The ballistic performance of a bullet-proof fabric can be increased by an increment in the friction between fibres. For enhancement of this performance, numerous studies on the shear thickening fluid ...(STF)-impregnated fabric have been conducted. The STF as a fluid, however, has inherent shortcomings. Our research aim is to understand and compare experimentally two different bullet-proof fabrics treated with a simple spray coating and STF impregnation. In this study, 71 single yarn pull-out and 90 high-velocity impact experiments were carried out. It was remarkable that the newly proposed Heracron fabric coated with a commercial coating spray increased by more than 90% the energy absorption before penetration, with only less than 15% of add-on weight. It was found that the polymeric anchors created on the fibre produce an exceptionally high level of friction between fibres, according to a microscopic morphological analysis and the single-yarn pull-out experiment. This study revealed the physical explanation of this coating method, showed its feasibility, and considered its effectiveness with excellent results.
Inspired by the hierarchic structure of the loofah sponge and the stiffness transformation behavior of sea cucumbers, a novel strategy to achieve multi-physics protection through a biomimetic ...structural design was proposed. This biomimetic structure with variable stiffness not only had the capability of force-thermal multi-physics protection but also could monitor the impact process.
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•A biomimetic composite (SIPM) with multi-physics protection was prepared.•The anti-impact and thermal insulation properties of SIPM were investigated.•The SIPM had a good sensing function and could be used for impact monitoring.•The SIPM had attractive prospects in the future application of the smart fire suit.
Inspired by the hierarchic structure of the loofah sponge and the stiffness transformation behavior of sea cucumbers, a novel strategy to achieve multi-physics protection through a biomimetic structural design was proposed. This biomimetic structure (STF-BIPM) effectively improved the stiffness of polyurethane (PU) foam. Furthermore, the stiffness of STF-BIPM increased with the compressive strain rate. STF-BIPM exhibited excellent impact resistance under dynamic loading. Compared with PU foam, the impact force of STF-BIPM was attenuated by 57.6 % and the energy absorption was improved by 25.7 %. Due to the porous structure of the PU part, STF-BIPM also had extremely low thermal conductivity (0.084 W m−1 k−1). Its upper surface temperature was only 39.0 °C after heating for 1000 s at 100.0 °C. Additionally, the STF-BIPM could act as a sensor to respond to the impact process and monitor human movement. Finally, based on the impact resistance, thermal insulation, and sensing of STF-BIPM, a smart fire suit was developed. The fire suit could not only achieve mechanical and thermal protection but also monitor mechanical injury behavior, which had a broad application prospect in the field of fire protection. This study provided an innovative means for the development of intelligent multi-physics protection.
The ballistic resistance of high-strength fabrics improves upon impregnation with Shear Thickening Fluids (STFs). The performance of such STF treated fabrics depends on the rheological properties of ...the STF which in turn are governed by the physicochemical properties of the STF. The present study utilizes rheological characterization of shear thickening silica-polyethylene glycol dispersions (of different material configurations in terms of packing fraction, particle size and continuous phase viscosity) to assess their performance and obtain the best STF material configuration for ballistic body armor applications based on the design criteria proposed herein. The ballistic performance assessment results showed that the STFs with high packing fractions which thicken discontinuously, are highly effective compared to the continuously shear thickening fluids. Furthermore, the use of smaller particle size dispersed phase in the STF formulation was determined to be economical. Also, the use of lower molecular weight dispersion medium was suggested as it allows for a broader working temperature range of the STF. Additionally, the technological issues associated with the development and the practical application of STF-Armor were addressed.
In order to further explore the forming limits of thin-wall tube necking and thickening, and obtain sufficient thickness of the tube in the thickening area, local electric pulse-assisted forming ...experiments were carried out to study the effects of current intensity and feed speed on the necking and thickening forming of thin-wall tube. The experimental results show that with the increase in current intensity, the temperature in the forming area of the tube increases, and the forming load for necking and thickening decreases. However, with the increase in feed speed, the overall forming load for necking and thickening increases in general, and the smaller feed speed is more conducive to forming. Taking into account the forming efficiency and electrode loss, the corresponding forming process window is obtained for the manufacturing of good parts. That is, during the necking stage, the current intensity shall not be less than 300 A, and the feed speed shall not exceed 10 mm/min. During the thickening stage, the current intensity should not be less than 1400 A, and the feed speed should not exceed 1 mm/min. The target part is finally formed, with an average wall thickness of 5.984 mm in the thickening zone and a thickening rate of 303.2%.
•Interplay of fluid rheology and mixed convection in backward facing step channel.•Effect of baffle configurations and arrangements along with fluid rheology.•Evaluation of Nusselt number, pressure ...drop and entropy generation.•Increase in reattachment length with increase in Ri and decrease in n.•Interdependence of fluid rheology, buoyancy, baffle configuration and arrangement.
The present study numerically investigates a two-dimensional, steady, laminar, incompressible and mixed convective flow of non-Newtonian fluid through a backward facing step channel with different baffle configurations. The power-law model is used to capture the confluence of fluid rheology and buoyancy for varying step to baffle distance, varying number of baffles and different arrangement (inline and staggered) of baffles. Different values of power-law index viz. n = 0.5, 0.8, 1, 1.2 and 1.5 are considered to encompass the shear-thinning (n < 1), shear-thickening (n > 1) as well as Newtonian fluids (n = 1) as a special case. The Reynolds number is fixed equal to 100 whereas the Richardson number has been varied within the range of 0.1–1 in the present investigation. The results obtained from the present investigation reveal the implications of power-law index, Richardson number and baffle configuration on the reattachment length, Nusselt number, pressure drop and entropy generation. The results show that the length of the recirculation zones formed in the backward facing step channel increases with increase in Richardson number and decreases with increase in power-law index. It is also found that the variation of heat transfer rate, pressure drop and entropy generation characteristics for varying step to baffle distance, different number of baffles and different arrangement and number of pairs of baffle is dictated by the interplay of power-law index and Richardson number. The findings of this study bear utility towards designing efficient thermodynamic system that can deliver maximum heat transfer with minimum irreversibility.
Water-locking flocs formed by ultrafine tailings particles will damage the thickener underflow concentration in the thickening process during paste preparation. The relationship between the ...mesostructure and seepage characteristics of tail mortar is typically ignored when investigating the deep dehydration stage. A shearing seepage test of an unclassified tailing–sedimentation bed was performed with copper tailings, and the morphology and geometric distribution of micropores were analyzed via X-ray computed tomography. Moreover, the shearing evolution of the micropore structure and seepage channel was investigated to evaluate the dewatering performance of underflow slurry using a three-dimensional reconstruction approach. The results show that porosity decreases considerably under shearing. The connected-pore ratio and the average radius of the throat channel reach peak values of 0.79 and 31.38 µm, respectively, when shearing is applied for 10 min. However, the reverse seepage velocity and absolute permeability in the bed decrease to various extents after shearing. Meanwhile, the maximum flow rate reaches 1.537 µm/s and the absolute permeability increases by 14.16%. Shearing alters the formation process and the pore structure of the seepage channel. Isolated pores connect to the surrounding flocs to form branch channels, which then become the main seepage channel and create the dominant water-seepage flow channel.
The influences of calcium content on thickening stage, dynamic oxidation and subsequent formation of cell walls in closed-cell aluminum foams were investigated by both precise thermodynamic and ...experimental studies. A novel technique was also used for the sample preparation, and the compendious characterization by transmission electron microscopy. Based on nanostructural investigations, the results indicated that in low calcium amounts (0.5 wt.%), the formation of complex oxide nanoparticles plays a key role in cell wall formation and bubble stabilization, when ignoring the effect of foaming agents. The higher calcium contents (1.5 wt.%) result in different thickening mechanism in which, relatively thick and brittle complex oxide layers are formed. Breaking of these oxide layers due to mechanical stirring causes the entrapment of several fragments in the interface of bubbles and consequently lead to cell wall stabilization. Due discussions were carried out about the effects of different thickening mechanism on the mechanical behavior of cell walls.
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•A novel method was used to investigate the cell walls of Ca-stabilized Al foams.•It was found that the Ca content can influence thickening step of the melt.•The structure of the formed cell walls is affected by Ca content.•The fracture and compressive behavior were illustrated based on Ca content.
The present study sought to characterize the rheological and thickening properties of Konjac glucomannan (KGM) and prepare thickening components for special medical purposes using KGM and ...maltodextrin as the primary raw materials and guar gum (GG), xanthan gum (XG), locust bean gum (LBG), and carrageenan (KC) as the supplemented materials. The formulation and preparation processes were optimized through single factor experiments taking sensory evaluation as an indicator. The results confirm that KGM had excellent thickening performance, reaching about 90 times its own mass. The optimal formulation process of the thickening components based on KGM was as follows: the mass concentration of the compound thickener (KGM/GG/XG/LBG/KC = 13:2:2:2:1) was 5.0-7.0 mg/mL; the maltodextrin concentration was 10.0 mg/mL; the brewing temperature of the thickening component was 60 °C with no restriction on consumption time. The rheology test results revealed that the thickening components had shear thinning characteristics, which could provide three different thickening effects of nectar-thick level (350 mPa·s), honey-thick level (1250 mPa·s), and pudding-thick level (1810 mPa·s) suitable for people with different degrees of chewing disorders. Overall, this study provides a theoretical basis and technical reference for KGM as a dietary nutrition support for patients with dysphagia.
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