Search

The clean extraction of vanadium from vanadium-bearing converter slag (VBCS) has important implications for the sustainable development of the vanadium industry. In this work, a process that included sieving, nonsalt roasting, and sulfuric acid leaching was carried out to extract vanadium from VBCS. First, through sieving, large particles of metallic iron were removed and vanadium with particle sizes of less than 150 µm was preliminarily enriched. Subsequently, the nonsalt roasting process was investigated in terms of the effects of temperature and time and the phase transformation mechanism. The structures of vanadium ferrospinel and fayalite were destroyed completely after roasting at 900 °C for 1.5 h, and vanadate, Fe 2 O 3 , SiO 2 , and Fe 2 TiO 5 formed in the roasted product. Finally, the systematic sulfuric acid leaching experiment demonstrated that over 97% of vanadium was extracted under optimal conditions. Meanwhile, the phase analysis of the leaching residue confirmed that vanadate was selectively leached into the solution. • A clean process for extracting vanadium from vanadium-bearing converter slag was studied. • The migration law of components in nonsalt roasting was revealed. • Over 97% of vanadium was selectively extracted by sulfuric acid leaching. • The leaching residue does not contain alkali metals and can be reused. [ABSTRACT FROM AUTHOR]

All metazoan guts are subject to opposing pressures wherein the immune system must eliminate pathogens while tolerating the presence of symbiotic microbiota. The Imd pathway is an essential defense against invading pathogens in insect guts, but tolerance mechanisms are less understood. Here, we find PGRP-LB and PGRP-SB express mainly in the anterior and middle midgut in a similar pattern to symbiotic Enterobacteriaceae bacteria along the Bactrocera dorsalis gut. Knockdown of PGRP-LB and PGRP-SB enhances the expression of antimicrobial peptide genes and reduces Enterobacteriaceae numbers while increasing abundance of opportunistic pathogens. Microbiota numbers recover to normal levels after the RNAi effect subsided. In contrast, high expression of PGRP-LC in the foregut allows increased antibacterial peptide production to efficiently filter the entry of pathogens, protecting the symbiotic bacteria. Our study describes a mechanism by which regional expression of PGRPs construct a protective zone for symbiotic microbiota while maintaining the ability to fight pathogens. [Display omitted] • Symbiotic bacteria are mainly located in the anterior midgut of B. dorsalis • Regional expression of PGRP matches the distribution pattern of symbiotic bacteria • PGRP-LB and PGRP-SB establish a protective zone for symbiotic bacteria colonization • PGRP-LC and AMPs in the foregut filter the pathogens to protect symbiotic bacteria Yao et al. find there is a regional expression of PGPR and spatial distribution of symbiotic bacteria along the Bactrocera dorsalis gut. This regional expression of PGPR tightly regulates the Imd pathway to construct a protective zone for symbiotic microbiota while maintaining the ability to fight pathogens. [ABSTRACT FROM AUTHOR]

This paper presents a new metamaterial plate (metaplate) made by a periodic repetition of 'frame-springs-mass' systems for vibration isolation. Numerical studies and experimental measurements demonstrate that the proposed structure show a complete 3D phononic bandgap in the low-frequency range. In the numerical computation of the transmission diagram, the self-weight gravity, the material damping, the geometry of the metaplate and different boundary conditions are considered. A prototype of the proposed metaplate, made of Polyamide, is fabricated by means of additive manufacturing and experimentally tested. The measured transmission diagram is in good agreement with numerical predictions, thus proving the proposed design and promoting potential applications such as low-frequency vibration isolation and stress wave mitigation. [ABSTRACT FROM AUTHOR]

ZnO has a large thermal conductivity that hinders its satisfactory thermoelectric performance. In this work, we add multiple dopants including S, C, Fe and Ni to ZnO simultaneously. A low thermal conductivity ∼3 W m−1 K−1 is obtained, with an initial composition ZnO-1%S-0.15 %C-4%Fe 2 O 3 -3%NiO (sample #7), and comparable to the lowest reported values of ZnO-based bulk samples. We attribute the reduction to the Ni induced lattice distortion and the Fe induced microstructural changes. This composition also shows the highest power factor that is ∼60% higher than ZnO due to its highest charge carrier concentration and mobility. The overall dominant carrier scattering is through acoustic phonons rather than impurities. The resultant zT is 2.4 times higher than that of undoped ZnO at 973 K. We find multiple doped ZnO exhibits better thermoelectric performance than any single doped counterpart, providing an effective way to improve the thermoelectric properties of ZnO and other oxides. [ABSTRACT FROM AUTHOR]

Vanadium extraction from water-cooled vanadium converter slag (VCS) is of great importance for improving the production efficiency of the vanadium industry. A clean process for extracting vanadium from water-cooled VCS is proposed. This process includes sieving, salt-free roasting, and sulfuric acid leaching. First, through sieving at 100 meshes, large particles of metallic iron are removed and vanadium is preliminarily enriched. Then, salt-free roasting at 950 °C for 1 h can destroy the structures of vanadium ferrospinel and fayalite completely. Vanadate (manganese vanadate, magnesium vanadate, and calcium vanadate), Fe 2 O 3 , SiO 2, and Fe 2 TiO 5 are formed in the roasted product. Mechanistic analysis shows that as the roasting temperature is increased, oxidation starts from the edges of particles. Vanadium is first oxidized into V4+ and gradually oxidized into V5+. Finally, systematic leaching experiments illustrate that under the optimal conditions, the leaching yields of V, Ca, Mn, and Mg are 94.99%, 89.24%, 46.81%, and 33.11%, respectively, whereas those of Fe, Si, and Cr are only 0.77%, 1.51%, and 1.03%, respectively. Furthermore, phase analysis demonstrates that only vanadate is selectively leached into the solution. The leaching residue does not contain alkali metals and can thus be used as raw material for iron production. [Display omitted] [ABSTRACT FROM AUTHOR]