This work focuses on investigating the self-healing characteristics and mechanism of Engineered Geopolymer Composites using fly ash and metakaolin as the precursors (MFA-EGCs). The hardened specimens ...were preloaded to different tensile strain levels followed by exposure to air and wet-dry cycles allowing for self-healing. Apart from the cracking characteristics, tensile properties were studied together with chemical and microstructural analyses. The results revealed a pronounced multiple cracking pattern and strain-hardening behavior for the MFA-EGCs. The number of cracks decreases significantly after the self-healing. High recovery ratios of the tensile strains and the ultimate tensile strengths were found, with some studied specimens showing even better tensile properties than the control specimens. It seems that air exposure is more favorable for the self-healing of the MFA-EGCs compared with exposure to the wet-dry cycles. Based on the results from SEM-EDS, XRD and FT-IR, it was concluded that amorphous aluminosilicate phases are the main healing products.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Emergent properties of natural biomaterials result from the collective effects of nanoscale interactions among ordered and disordered domains. Here, using recombinant sequence design, we have created ...a set of partially ordered polypeptides to study emergent hierarchical structures by precisely encoding nanoscale order-disorder interactions. These materials, which combine the stimuli-responsiveness of disordered elastin-like polypeptides and the structural stability of polyalanine helices, are thermally responsive with tunable thermal hysteresis and the ability to reversibly form porous, viscoelastic networks above threshold temperatures. Through coarse-grain simulations, we show that hysteresis arises from physical crosslinking due to mesoscale phase separation of ordered and disordered domains. On injection of partially ordered polypeptides designed to transition at body temperature, they form stable, porous scaffolds that rapidly integrate into surrounding tissue with minimal inflammation and a high degree of vascularization. Sequence-level modulation of structural order and disorder is an untapped principle for the design of functional protein-based biomaterials.
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IJS, KISLJ, NUK, SBMB, UL, UM, UPUK
We propose a novel nearest-neighbors approach to organize and curb the growth of radial basis function network in kernel adaptive filtering (KAF). The nearest-instance-centroid-estimation (NICE) ...kernel least-mean-square (KLMS) algorithm provides an appropriate time-space tradeoff with good performance. Its centers in the input/feature space are organized by quasi-orthogonal regions for greatly simplified filter evaluation. Instead of using all centers to evaluate/update the function approximation at every new point, a linear search among the iteratively-updated centroids determines the partial function to be used, naturally forming locally-supported partial functionals. Under this framework, partial functionals that compose the adaptive filter are quickly stored/retrieved based on input, each corresponding to a specialized "spatial-band" subfilter. The filter evaluation becomes the update of one of the subfilters, creating a content addressable filter bank (CAFB). This CAFB is incrementally updated for new signal applications with mild constraints, always using the past-learned partial filter sums, opening the door for transfer learning and significant efficiency for new data scenarios, avoiding training from scratch as have been done since the invention of adaptive filtering. Using energy conservation relation, we show the sufficient condition for mean square convergence of the NICE-KLMS algorithm and establish the upper and lower bounds of steady-state excess-mean-square-error (EMSE). Simulations on chaotic time-series prediction demonstrate similar levels of accuracy as existing methods, but with much faster computation involving fewer input samples. Simulations on transfer learning using both synthetic and real-world data demonstrate that NICE CAFB can leverage previously learned knowledge to related task or domain.
One-dimensional flexible supercapacitor yarns are of considerable interest for future wearable electronics. The bottleneck in this field is how to develop devices of high energy and power density, by ...using economically viable materials and scalable fabrication technologies. Here we report a hierarchical graphene-metallic textile composite electrode concept to address this challenge. The hierarchical composite electrodes consist of low-cost graphene sheets immobilized on the surface of Ni-coated cotton yarns, which are fabricated by highly scalable electroless deposition of Ni and electrochemical deposition of graphene on commercial cotton yarns. Remarkably, the volumetric energy density and power density of the all solid-state supercapacitor yarn made of one pair of these composite electrodes are 6.1 mWh cm(-3) and 1,400 mW cm(-3), respectively. In addition, this SC yarn is lightweight, highly flexible, strong, durable in life cycle and bending fatigue tests, and integratable into various wearable electronic devices.
Pd–Cu catalysis is combined with in situ electrolytic H2 evolution for NO3 – reduction with protonated polypyrrole (PPy) as a cathode. The surface of PPy is not only beneficial for H2 evolution, but ...exclusive for NO3 – adsorption, and thus inhibits NO3 – reduction. Meanwhile, the in situ H2 generation exhibits a much higher utilization efficiency because of the smaller bubble size and higher dispersion. The Pd–Cu catalysts with the ratios of 6:1 and 4:1 exhibit the highest NO3 ––N removal (100%) and N2 selectivity (93–95%) after 90 min. In comparison with the results obtained with other cathode materials (Ti, Cu, Co3O4, and Fe2O3) and obtained by other researchers, the new process shows a faster NO3 ––N reduction rate and much higher N2 selectivity. However, the O2 generated on the anode can oxidize Cu to Cu2O that may work as the catalyst for NO3 ––N reduction to NH4 +–N by H2, resulting in more than 60% NH4 +–N generated without a proton exchange membrane. Both the PPy film and Pd–Cu catalyst exhibit good stability and there is no Cu2+ or Pd2+ in solution after reaction. Real industrial wastewater is further treated in this system, the NO3 ––N is reduced from 670 mg L–1 to less than 100 mg L–1 in 90 min, and only little amount of NH4 +–N is generated.
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IJS, KILJ, NUK, PNG, UL, UM
The characteristics of municipal solid waste incineration (MSWI) fly ash, surface leaching toxicity and successive leaching concentration of heavy metals from MSWI fly ash-cement hardened pastes were ...studied. And, the relationships between leaching concentrations of heavy metals and leaching time were also discussed. Experimental results showed that immobilization effect of cement on MSWI fly ash is good. Even if MSWI fly ash-cement hardened pastes were damaged, the leaching toxicity is still in a safety range. In early leaching stage, the surface leaching rate is relatively a little high, up to 10
−5–10
−4
cm
d
−1 order of magnitude, in the later time of leaching, its rate rapidly declined, down to 10
−7. Most of leached heavy metals are produced at early ages. The leaching concentration of heavy metals and leaching time has strong positive relationships. In factual utilizing circumstances, heavy metals’ leaching from MSWI fly ash-cement hardened pastes is a very slow and gradually diluting process. The leaching toxicity of heavy metals is far lower than that of the National Standard of China, and minimum harmful matters can be contained and released in the environment. Reusing of MSWI fly ash as partial replacement for cement in concrete mixes is potentially feasible.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Harvesting micro‐droplets from fog is a promising method for solving global freshwater crisis. Different types of fog collectors have been extensively reported during the last decade. The improvement ...of fog collection can be attributed to the immediate transportation of harvested water, the effective regeneration of the fog gathering surface, etc. Through learning from the nature's strategy for water preservation, the hydrophobic/hydrophilic cooperative Janus system that achieved reinforced fog collection ability is reported here. Directional delivery of the surface water, decreased re‐evaporation rate of the harvested water, and thinner boundary layer of the collecting surface contribute to the enhancement of collection efficiency. Further designed cylinder Janus collector can facilely achieve a continuous process of efficient collection, directional transportation, and spontaneous preservation of fog water. This Janus fog harvesting system should improve the understanding of micro‐droplet collection system and offer ideas to solve water resource crisis.
Taking inspiration from nature's strategy for water collection and preservation, a hydrophobic/hydrophilic cooperative Janus system is proposed as a promising fog harvesting apparatus. This Janus fog collector can achieve a continuous process containing efficient collection, directional transport, and rapid preservation of fog water.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Engineering electronic properties by elemental doping is a direct strategy to design efficient catalysts towards CO2 electroreduction. Atomically thin SnS2 nanosheets were modified by Ni doping for ...efficient electroreduction of CO2. The introduction of Ni into SnS2 nanosheets significantly enhanced the current density and Faradaic efficiency for carbonaceous product relative to pristine SnS2 nanosheets. When the Ni content was 5 atm %, the Ni‐doped SnS2 nanosheets achieved a remarkable Faradaic efficiency of 93 % for carbonaceous product with a current density of 19.6 mA cm−2 at −0.9 V vs. RHE. A mechanistic study revealed that the Ni doping gave rise to a defect level and lowered the work function of SnS2 nanosheets, resulting in the promoted CO2 activation and thus improved performance in CO2 electroreduction.
Nickel in thin tin: Atomically thin SnS2 nanosheets were modified by Ni doping for efficient electroreduction of CO2. Introduction of Ni into SnS2 nanosheets enhanced current density and Faradaic efficiency for carbonaceous product relative to pristine SnS2 nanosheets. When the Ni content was 5 at. %, Faradaic efficiency was 93 % with a current density of 19.6 mA cm−2 at −0.9 V vs. RHE.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Porous graphitic carbon nitride (g-C
3
N
4
) was prepared by a simple pyrolysis of urea, and then a g-C
3
N
4
-Pt-TiO
2
nanocomposite was fabricated
via
a facile chemical adsorption followed by a ...calcination process. The obtained products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance absorption spectra, and electron microscopy. It is found that the visible-light-induced photocatalytic hydrogen evolution rate can be remarkably enhanced by coupling TiO
2
with the above g-C
3
N
4
, and the g-C
3
N
4
-Pt-TiO
2
composite with a mass ratio of 70 : 30 has the maximum photoactivity and excellent photostability for hydrogen production under visible-light irradiation, and the stable photocurrent of g-C
3
N
4
-TiO
2
is about 1.5 times higher than that of the bare g-C
3
N
4
. The above experimental results show that the photogenerated electrons of g-C
3
N
4
can directionally migrate to Pt-TiO
2
due to the close interfacial connections and the synergistic effect existing between Pt-TiO
2
and g-C
3
N
4
where photogenerated electrons and holes are efficiently separated in space, which is beneficial for retarding the charge recombination and improving the photoactivity.
A visible-light-responsive g-C
3
N
4
-Pt-TiO
2
nanocomposite with efficient photogenerated carrier separation in space was fabricated.
Here, a smart fluid‐controlled surface is designed, via the rational integration of the unique properties of three natural examples, i.e., the unidirectional wetting behaviors of butterfly's wing, ...liquid‐infused “slippery” surface of the pitcher plant, and the motile microcilia of micro‐organisms. Anisotropic wettability, lubricated surfaces, and magnetoresponsive microstructures are assembled into one unified system. The as‐prepared surface covered by tilted microcilia achieves significant unidirectional droplet adhesion and sliding. Regulating by external magnet field, the directionality of ferromagnetic microcilia can be synergistically switched, which facilitates a continuous and omnidirectional‐controllable water delivery. This work opens an avenue for applications of anisotropic wetting surfaces, such as complex‐flow distribution and liquid delivery, and extend the design approach of multi‐bioinspiration integration.
Three natural inspirations, i.e., butterfly wings, pitcher plants, and microcilia, are integrated into a surface to design multifunctional interface materials. Based on this multi‐bioinspiration, a microcilia surface lubricated by silicone oil is prepared, which achieves unidirectional wetting behavior with magnetocontrollability.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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