Display omitted
•GEP algorithm is utilized for predicting mechanical properties of concrete incorporating WFS.•Simple and accurate formulations with a wide range of applicability have been ...proposed.•Proposed models can promote the re-utilization of hazardous WFS for development of green concrete.
Waste foundry sand (WFS) is a major pollutant generated from metal casting foundries and is classified as a hazardous material due to the presence of organic and inorganic pollutants which can cause adverse environmental impact. In order to promote the re-utilization of WFS, gene expression programming (GEP) has been employed in this study to develop empirical models for prediction of mechanical properties of concrete made with WFS (CMWFS). An extensive and reliable database of mechanical properties of CMWFS is established through a comprehensive literature review. The database comprises of 234 compressive strength, 163 split tensile strength and 85 elastic modulus results. The four most influential parameters i.e. water-to-cement ratio, WFS percentage, WFS-to-cement content ratio and fineness modulus of WFS are considered as the input parameters for modelling. The mechanical properties can be estimated by the application of proposed simplified mathematical expressions. The performance of the models is assessed by conducting parametric analysis, applying statistical checks and comparing with regression models. The results reflected that the proposed models are accurate and possess a high generalization and prediction capability. The findings of this study can enhance the re-usage of WFS for development of green concrete leading to environmental protection and monetary benefits.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Rational design and exploration of robust and low‐cost bifunctional oxygen reduction/evolution electrocatalysts are greatly desired for metal–air batteries. Herein, a novel high‐performance oxygen ...electrode catalyst is developed based on bimetal FeCo nanoparticles encapsulated in in situ grown nitrogen‐doped graphitic carbon nanotubes with bamboo‐like structure. The obtained catalyst exhibits a positive half‐wave potential of 0.92 V (vs the reversible hydrogen electrode, RHE) for oxygen reduction reaction, and a low operating potential of 1.73 V to achieve a 10 mA cm−2 current density for oxygen evolution reaction. The reversible oxygen electrode index is 0.81 V, surpassing that of most highly active bifunctional catalysts reported to date. By combining experimental and simulation studies, a strong synergetic coupling between FeCo alloy and N‐doped carbon nanotubes is proposed in producing a favorable local coordination environment and electronic structure, which affords the pyridinic N‐rich catalyst surface promoting the reversible oxygen reactions. Impressively, the assembled zinc–air batteries using liquid electrolytes and the all‐solid‐state batteries with the synthesized bifunctional catalyst as the air electrode demonstrate superior charging–discharging performance, long lifetime, and high flexibility, holding great potential in practical implementation of new‐generation powerful rechargeable batteries with portable or even wearable characteristic.
Bamboo‐like FeCo alloy encapsulated in nitrogen‐doped carbon nanotubes exhibits superior catalytic oxygen reduction and oxygen evolution performance than that of noble metal benchmarks, which benefits from the nitrogen‐rich and defect‐rich catalyst surface. The all‐solid‐state zinc–air batteries equipped by the synthesized materials show low charging/discharging overpotentials, long lifetime, and high flexibility, suitable for practical application.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Hall-Petch relationship in Mg alloys: A review Yu, Huihui; Xin, Yunchang; Wang, Maoyin ...
Journal of materials science & technology,
February 2018, 2018-02-00, Volume:
34, Issue:
2
Journal Article
Peer reviewed
Grain refinement could effectively enhance yield strength of Mg alloys according to the well-known Hall-Petch theory. For decades, many studies have been devoted to the factors influencing the ...Hall-Petch slope (k) in Mg alloys. Understanding the factors influencing k and their mechanisms could offer guidance to design and produce high-strength Mg alloys through effective grain refinement hardening. A review and comments of the past work on the factors influencing k in Mg alloys are presented. Results of these previous investigations demonstrate that the value of k in Mg alloys varies with texture, grain size, temperature and stain. The influence of texture and grain size on k is found to be an essential result of the variation of deformation mode on k value. Without the variation of deformation modes, it is revealed that texture could also impose a significant effect on k and this is also summarized and discussed in this paper. The reason for texture effect on k is analyzed based on the mechanism of Hall-Petch relationship. In addition, it is found in face-centered cubic (fcc) or body-centered cubic (bcc) metals that boundary parameters (boundary coherence, boundary energy and boundary diffusivity) could strengthen twinning or slips to a different extent. Therefore, the role of boundary parameters is also extended into the k values in Mg alloys and discussed in this paper. In the end, we discuss the future research perspective of Hall-Petch relationship in Mg alloys.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
A metal‐free method for the construction of oxazolidine‐2,4‐diones and oxindoles was discussed. Using iodine monochloride (ICl) as both the reaction promoter and iodide source, the iodolactonization ...of N‐Boc acrylamides proceeded readily and provided the corresponding iodo oxazolidine‐2,4‐diones and oxazolidin‐2‐ones in good isolated yields. The obtained oxazolidine‐2,4‐diones can be used as key intermediates in the synthesis of toloxatone. When N‐alkyl‐N‐arylacrylamide derivatives were subjected to the same reaction, iodocarbocyclization products 3,3‐disubstituted oxindoles were obtained. The obtained oxindoles can be used as key intermediates in the synthesis of the alkaloids (±)‐esermethole and (±)‐physostigmine.
A metal‐free method for the construction of oxazolidine‐2,4‐diones and oxindoles is reported herein. The resulting products can be used as key intermediates in synthesis of bioactive compounds such as toloxatone, (±)‐esermethole, and (±)‐physostigmine.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Flexible lithium-ion batteries (FLIBs) potentially offer lithium-ion battery energy density required for the production of flexible electronics. The design of FLIBs depends not only on the electrode ...materials but also on the entire weight of the battery device. However, low capacity contribution from the flexible substrate and poor interactions between the flexible substrate and active electrode materials lead to low capacity, representing low energy density. Herein, we concentrated on designing a flexible substrate (carbon cloth, CC), improving its conductivity and surface area to deliver high capacity, and further coating porous NiCo 2 O 4 nanowires on it to achieve a monolithic anode for high-gravimetric energy density FLIBs. Theoretical and in situ analyses were used to investigate Li-ion pathways and capacity contribution of the flexible substrate, respectively. In this regard, a 39.0 cm 2 all-flexible lithium-ion battery (with an entire weight of 281 mg) with high gravimetric energy density (314 W h kg −1 ), excellent flexibility, and good storage performance is attained, and it exhibits potential application for future flexible energy storage devices.
Herein, we demonstrate the use of heterostructures comprised of Co/β-Mo
C@N-CNT hybrids for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline electrolyte. The ...Co can not only create a well-defined heterointerface with β-Mo
C but also overcomes the poor OER activity of β-Mo
C, thus leading to enhanced electrocatalytic activity for HER and OER. DFT calculations further proved that cooperation between the N-CNTs, Co, and β-Mo
C results in lower energy barriers of intermediates and thus greatly enhances the HER and OER performance. This study not only provides a simple strategy for the construction of heterostructures with nonprecious metals, but also provides in-depth insight into the HER and OER mechanism in alkaline solution.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In this work, a record high thermoelectric figure‐of‐merit ZT of 1.6 ± 0.2 at 873 K in p‐type polycrystalline Bi0.94Pb0.06CuSe1.01O0.99 by a synergy of rational band manipulation and novel ...nanostructural design is reported. First‐principles density functional theory calculation results indicate that the density of state at the Fermi level that crosses the valence band can be significantly reduced and the measured optical bandgap can be enlarged from 0.70 to 0.74 eV by simply replacing 1% O with 1% Se, both indicating a potentially reduced carrier concentration and in turn, an improved carrier mobility and a boosted power factor up to 9.0 µW cm−1 K−2. Meanwhile, comprehensive characterizations reveal that under Se‐rich condition, Cu2Se secondary microphases and significant lattice distortions triggered by Pb‐doping and Se‐substitution can be simultaneously achieved, contributing to a reduced lattice thermal conductivity of 0.4 W m−1 K−1. Furthermore, a unique shear exfoliation technique enables an effective grain refinement with higher anisotropy of the polycrystalline pellet, leading to a further improved power factor up to 10.9 µW cm−1 K−2 and a further reduced lattice thermal conductivity of 0.30 W m−1 K−1, which gives rise to record high ZT.
A record high thermoelectric figure‐of‐merit ZT of 1.6 ± 0.2 at 873 K in p‐type polycrystalline Bi0.94Pb0.06CuSe1.01O0.99 by a synergy of rational band manipulation and novel nanostructural design is reported.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Lithium-oxygen batteries with ultrahigh energy density have received considerable attention as of the future energy storage technologies. The development of effective electrocatalysts and a ...corresponding working mechanism during cycling are critically important for lithium-oxygen batteries. Here, a single cobalt atom electrocatalyst is synthesized for lithium-oxygen batteries by a polymer encapsulation strategy. The isolated moieties of single atom catalysts can effectively regulate the distribution of active sites to form micrometre-sized flower-like lithium peroxide and promote the decomposition of lithium peroxide by a one-electron pathway. The battery with single cobalt atoms can operate with high round-trip efficiency (86.2%) and long-term stability (218 days), which is superior to a commercial 5 wt% platinum/carbon catalyst. We reveal that the synergy between a single atom and the support endows the catalyst with excellent stability and durability. The promising results provide insights into the design of highly efficient catalysts for lithium-oxygen batteries and greatly expand the scope of future investigation.
An artificial while very stable solid electrolyte interphase film is formed on lithium metal using an electrochemical strategy. When this protected Li anode is first used in a Li–O2 battery, the film ...formed on the anode can effectively suppress the parasitic reactions on the Li anode/electrolyte interface and significantly enhance the cycling stability of the Li–O2 battery.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
PDF
