Search

DC grid has a prospect of application in collecting and transmitting large-scale renewable energy over long distance. However, the randomness and fluctuation of the renewable power may hamper the stable operation of DC grid. Energy storage device is able to actively absorb or supplement active power, which can be used to smooth the power fluctuation. The paper investigates a DC grid topology with energy storage and proposes a coordinated control strategy. The proposed strategy enables coordinated control of the renewable energy output power, pumped storage power and the grid consuming power. During the steady state, the control strategy enables the system DC voltage stable and power flow of the grid under zero-error control. During the faulted time, the coordinate control strategy enables the converter fast response and maintains the system DC voltage within safety margin. The effectiveness of the coordinated control strategy is verified by simulation in PSCAD/EMTDC. [ABSTRACT FROM AUTHOR]

Titanium dioxide nanoparticle (n-TiO 2 ) is a widely used nanomaterial, which is inevitably released as a residue into aquatic ecosystems during material production and usage. However, the effects of n-TiO 2 on aquatic microbial communities have not been completely elucidated. This study examined the toxic effects of n-TiO 2 on eukaryotic and prokaryotic microbial communities in freshwater environments. We determined that n-TiO 2 had a greater inhibitory effect on the growth of eukaryotic algae than cyanobacteria in monocultures. A similar phenomenon was observed in a microcosm experiment, revealing that n-TiO 2 slightly reduced the content of chlorophyll-a but evidently increased the phycocyanin content. Moreover, the alpha diversity of the eukaryotic community was not affected, whereas its beta diversity increased with exposure to n-TiO 2 . Although n-TiO 2 altered the composition of freshwater microbial communities, it did not change the functions of the prokaryotic community, which might be attributed to the functional redundancy of microbiota. Co-occurrence network analysis indicated that n-TiO 2 destabilized the freshwater community, especially the eukaryotic community, and potentially disturbed the aquatic ecosystem. Our study revealed that the ecological risk of n-TiO 2 on aquatic microbial communities is complex; hence, rational utilization of n-TiO 2 should be emphasized., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Thallium (Tl) contamination in natural waters can pose a severe risk to human health. In this study, a magnetically responsive Fe 3 O 4 @TiO 2 core-shell adsorbent was developed for the effective removal of thallium(I) from water. The isoelectric point of the adsorbent surface was decreased from 6.0 to 4.8 due to the loading of nano-sized TiO 2 , leading to an enhanced electrostatic interaction between the adsorbent and Tl(I) ions in a wider pH range. The Fe 3 O 4 @TiO 2 magnetic adsorbent exhibited a threefold higher BET specific surface area compared to pristine Fe 3 O 4 particles. The kinetics study showed that approximately 82% of the maximum Tl(I) loading amount could be achieved within 30 min at the initial Tl(I) concentration of 8 mg/L and adsorbent dosage of 0.1 g/L. The adsorption of Tl(I) was significantly increased with increasing solution pH. The experimental data was better fitted by the Langmuir and Temkin isotherms than the Freundlich isotherm and the maximum adsorption capacity of the magnetic adsorbent was 101.5 mg/g at pH 7.0. The interference of co-existing cations in the Tl(I) adsorption followed the subsequence: Cu 2+ > Mg 2+ > Ca 2+ > Na + . The hydroxyl groups bonded on titanium atoms might play a key role in the uptake of Tl(I) ions. During the adsorption, the Tl(I) ions can be effectively adsorbed on the adsorbent surface via the formation of Ti-O-Tl linkages. Graphical Abstract.