•Roasted gold concentrate was investigated as a flux material for the smelting of waste PCBs.•Au and Ag were effectively recovered from waste PCBs - gold concentrate mixtures.•Effect of gold ...concentrate on the physicochemical properties of molten slags was investigated.•Residual sulfur in roasted gold concentrate significantly changed the phase of Cu alloys.
Waste printed circuit boards (PCBs) are highly toxic materials because of the hazardous substances that are incorporated into them. An advanced recycling technology based on pyrometallurgical treatment using Au concentrate as a flux material was developed in this study. The benefits of employing roasted gold concentrate (RGC) in the smelting process of waste PCBs were demonstrated through high-temperature experiments. The major oxide compositions of PCBs (CaO, Al2O3, and SiO2) were fluxed using oxidized Au concentrate composed of FetO and SiO2. Quaternary slag systems (CaO-FetO-Al2O3-SiO2) were formed during the smelting process, which rendered the process of separation of oxide impurities from Cu-based alloys easier. Precious metals (Au and Ag) were effectively recovered from waste PCBs and Au concentrate in the form of a metal alloy that required further treatment by leaching and extraction. Residual S in the RGC significantly changed the alloy phases. A large quantity of S was formulated into a matte phase, while a small amount of S was dissolved into a Cu-Fe metal alloy. The subsequent hydrometallurgical process was optional. Electrorefining or pressure leaching could be applied depending on the type of Cu alloy.
Sodium batteries have been recognized as a promising alternative to lithium‐ion batteries. However, the liquid electrolyte used in these batteries has inherent safety problems. Polymer electrolytes ...have been considered as safer and more reliable electrolyte systems for rechargeable batteries. Herein, a thermoplastic polyurethane elastomer‐based gel polymer electrolyte with high ionic conductivity and high elasticity was reported. It had an ambient‐temperature ionic conductivity of 1.5 mS cm−1 and high stretchability, capable of withstanding 610 % strain. Coordination between Na+ ions and polymer chains increased the degree of salt dissociation in the gel polymer electrolyte compared with the liquid electrolyte. An Na/Na3V2(PO4)3 cell assembled with gel polymer electrolyte exhibited good cycling performance in terms of discharge capacity, cycling stability, and rate capability, which was owing to the effective trapping ability of organic solvents in the polymer matrix and uniform flux of sodium ions through the gel polymer electrolyte.
A gel solution: A sodium‐metal cell fabricated with a sodium‐metal anode, an Na3V2(PO4)3 cathode, and a gel polymer electrolyte based on a thermoplastic polyurethane elastomer exhibits good cycling performance in terms of discharge capacity, cycling stability, and rate capability owing to effective trapping of organic solvents in the polymer matrix and uniform sodium‐ion flux through the gel polymer electrolyte.
Concentrated radioactive elements and high alkalinity prevent the general usage of red mud to the glass-ceramics and construction materials. Gold tailing has inadequate particle sizes (≤100μm) for ...use in ceramic industry, and waste limestone contains lime of too low quantity. Hence, the combinatorial design for the utilization of these industrial wastes was investigated to obtain functional and environmentally stabilized glass ball. Red mud (RM) was vitrified by melting and granulation process with addition of gold tailing (GT) and waste limestone (WL). The mass ratio between raw materials (RM:GT:WL=1:1:1) and the viscosity of the glass melts (1.5Pa·s) were optimized for the melting and granulation process. From gamma spectroscopy, the radioactive nuclide concentration in the granulated glass ball was significantly decreased. Also, the granulated glass balls showed excellent resistance against leaching of heavy metal ions based on the results of the toxicity characteristic leaching procedure (TCLP).
The complications of the conventional medialized design for reverse total shoulder arthroplasty (RSA) are increased scapular notching, and decreased external rotation and deltoid wrapping. Currently, ...lateralization design RSA, which avoid scapular notching and improve impingement-free range of motion, is commonly used. Especially, humeral lateralization design was most commonly used and glenoid lateralization design was preferred for glenoid abnormities. We compared mid-term clinical and radiologic outcomes of glenoid and humeral lateralization RSA in an Asian population in this study.
We enrolled 124 shoulders of 122 consecutive patients (mean age 73.8 ± 6.8 years) who received glenoid or humeral lateralization RSA from May, 2012 to March, 2019. We divided these patients into two groups according to RSA using either glenoid or humeral lateralization design. These different designs were introduced consecutively in Korea. The clinical and radiological results of 60 glenoid lateralization RSA (Group I, 60 patients) and 64 humeral lateralization RSA (Group II, 62 patients) were retrospectively evaluated and also were compared between the two groups. All patients were followed for mean 3 years.
The clinical and radiologic outcomes of the two groups did not differ significantly, including scapular notching (p = 0.134). However, humeral lateralization RSA showed a larger glenoid-tuberosity (GT) distance (p = 0.000) and less distalization shoulder angle (DSA) (p = 0.035). The complication rate did not differ significantly either. But, revision surgery was performed for 2 humeral loosening in the Group II.
The clinical and radiologic outcomes of the two groups did not differ significantly, including scapular notching at mid-term follow-up. However, humeral lateralization design showed larger GT distance and less DSA. Humeral lateralization design RSA could preserve the normal shoulder contour due to a larger GT distance (more lateralization) and provide less deltoid tension due to less DSA (less distalization of COR).
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Noting the source-dependent properties of dissolved organic matter (DOM), this study explored the recoverable compounds by solid phase extraction (SPE) of two common sorbents (C18 and PPL) eluted ...with methanol solvent for contrasting DOM sources via fluorescence excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Fresh algae and leaf litter extracts DOM, one riverine DOM, and one upstream lacustrine DOM were selected for the comparison. C18 sorbent was generally found to extract more diverse molecular formula, relatively higher molecular weight, and more heteroatomic DOM compounds within the studied mass range than PPL sorbent except for the leaf litter extract. Even with the same sorbent, the main molecular features of the two end member DOM were distributed on different sides of the axes of a multivariate ordination, indicating the source-dependent characteristics of the recoverable compounds by the sorbents. In addition, further examination of the molecular formula uniquely present in the two end members and the upstream lake DOM suggested that proteinaceous, tannin-like, and heteroatomic DOM constituents might be potential compound groups which are labile and easily degraded during their mobilization into downstream watershed. This study provides new insights into the sorbent selectivity of DOM from diverse sources and potential lability of various compound groups.
In this study, we propose the use of artificial synaptic transistors with coplanar-gate structures fabricated on paper substrates comprising biocompatible and low-cost potato-starch electrolyte and ...indium-gallium-zinc oxide (IGZO) channels. The electrical double layer (EDL) gating effect of potato-starch electrolytes enabled the emulation of biological synaptic plasticity. Frequency dependence measurements of capacitance using a metal-insulator-metal capacitor configuration showed a 1.27 μF/cm
at a frequency of 10 Hz. Therefore, strong capacitive coupling was confirmed within the potato-starch electrolyte/IGZO channel interface owing to EDL formation because of internal proton migration. An electrical characteristics evaluation of the potato-starch EDL transistors through transfer and output curve resulted in counterclockwise hysteresis caused by proton migration in the electrolyte; the hysteresis window linearly increased with maximum gate voltage. A synaptic functionality evaluation with single-spike excitatory post-synaptic current (EPSC), paired-pulse facilitation (PPF), and multi-spike EPSC resulted in mimicking short-term synaptic plasticity and signal transmission in the biological neural network. Further, channel conductance modulation by repetitive presynaptic stimuli, comprising potentiation and depression pulses, enabled stable modulation of synaptic weights, thereby validating the long-term plasticity. Finally, recognition simulations on the Modified National Institute of Standards and Technology (MNIST) handwritten digit database yielded a 92% recognition rate, thereby demonstrating the applicability of the proposed synaptic device to the neuromorphic system.
Transition metal chalcogenides have received significant attention as electronic materials owing to their tunable electronic transport properties and unique crystal structures. In this work, the ...electrical, thermal, and thermoelectrical transport properties of FeTe2-CoTe2 solid solution system were investigated by synthesizing a series of (Fe1–xCox)Te2 polycrystalline alloys with x = 0, 0.25, 0.5, 0.75, and 1. FeTe2 and CoTe2 exhibited identical orthorhombic structures and formed a complete solid solution. (Fe1–xCox)Te2 system exhibits wide range of electronic transport characteristics; CoTe2 exhibits metallic conduction with high electrical conductivity of ∼8000 S/cm with electron carriers, whereas FeTe2 exhibits semiconducting conduction with relatively low electrical conductivity of ∼300 S/cm with hole carriers at room temperature. The optimum carrier transport for high power factor of 1.53 mW/cmK2 at 600 K is observed for (Fe0.5Co0.5)Te2 composition. The electronic band dispersions of FeTe2, (Fe0.5Co0.5)Te2, and CoTe2 were calculated by using the density functional theory and it was found that a distinct flat band is present near the Fermi level for Fe0.5Co0.5Te2, supporting the high power factor of Fe0.5Co0.5Te2. As the lattice thermal conductivity is reduced for the solid-solution samples with additional point defect scattering, the thermoelectric figure of merit (zT) increased significantly to 0.18 for Fe0.5Co0.5Te2 compared to 0.001 for FeTe2 or 0.08 for CoTe2 at 600 K.
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•A series of (Fe1–xCox)Te2 alloys (x = 0, 0.25, 0.5, 0.75, and 1) was investigated.•Complete solid solution is formed for (Fe1–xCox)Te2 (x = 0, 0.25, 0.5, 0.75, and 1).•FeTe2-CoTe2 system provides a wide variety of electrical transport properties from semiconducting to metallic.•Band dispersions were calculated for FeTe2, Fe0.5Co0.5Te2 and CoTe2 using the density functional theory.•Power factor and thermoelectric figure of merit are optimized for Fe0.5Co0.5Te2.
•CFD analysis was performed to evaluate the thermal–hydraulic characteristics of emergency cooldown tank (ECT) in a SMART.•The temperature distribution of the CFD results is in good agreement with ...the experiment results.•The water level in ECT increases due to the volume was well simulated in CFD analysis.
Computational Fluid Dynamics (CFD) analysis was performed to evaluate the thermal–hydraulic characteristics of emergency cooldown tank (ECT) in a Passive Residual Heat Removal System (PRHRS) of SMART. ECT is the ultimate heat sink of the PRHRS. Experimental results about the small-break loss-of-coolant accident (SBLOCA) scenario for a 0.4 in. line break in the safety-injection system (SIS) were used to compare and validate the CFD results. The geometrical model for CFD considered only the ECT and internal heat exchanger. The boundary and initial conditions of CFD analysis were based on the experimental data. The transient analysis was performed for 6000 s. The temperature distribution of the CFD results is in good agreement with the experiment results. The water level in ECT increases due to the volume expansion according to the temperature, which was well simulated in CFD analysis.
SnTe is a promising thermoelectric material for mid-temperature waste heat recovery. Recently, a high thermoelectric performance (zT) is reported in In and Sr co-doped Sn1−3xInxSr2xTe (x = 0.0 – ...0.03). A high zT of 1.075 is achieved when x = 0.02 at 823 K. The In dopant is known to engineer the valence band of the SnTe by forming a resonant state near 300 K. The Sr dopant converges the two valence bands of the SnTe. However, when both In and Sr are doped in SnTe while keeping their atomic ratio constant, their effects on band engineering with increasing are not known. Here, the effects of resonant state formation and band convergence on electronic transport properties of Sn1−3xInxSr2xTe (x = 0.0 – 0.03) are investigated from the estimated temperature-dependent electronic band parameters. Both the resonant state formation and band convergence become most significant at the x = 0.02. According to the single parabolic band model, the zT of the x = 0.02 can be further improved to ∼1.834 (approximately 70 % zT improvement) upon carrier concentration tuning.
•Resonant state formation and band convergence are induced in In and Sr co-doped SnTe.•There are band convergences due to temperature and doping in the co-doped SnTe.•Weighted mobility is a good indicator of band convergence.•Theoretical maximum zT of In and Sr co-doped SnTe is as high as ∼1.8 at 823 K.
