gStore: A Graph-based SPARQL Query Engine

We address efficient processing of SPARQL queries over RDF datasets. The proposed techniques, incorporated into the gStore system, handle, in a uniform and scalable manner, SPARQL queries with wildcards and aggregate operators over dynamic RDF datasets. Our approach is graph-based. We store RDF data as a large graph, and also represent a SPARQL query as a query graph. Thus the query answering problem is converted into a subgraph matching problem. To achieve efficient and scalable query processing, we develop an index, together with effective pruning rules and efficient search algorithms. We propose techniques that use this infrastructure to answer aggregation queries. We also propose an effective maintenance algorithm to handle online updates over RDF repositories. Extensive experiments confirm the efficiency and effectiveness of our solutions

Single-atomic tungsten-doped Co3O4 nanosheets for enhanced electrochemical kinetics in lithium–sulfur batteries

The practical application of lithium–sulfur batteries (LSBs) is severely hindered by the undesirable shuttling of lithium polysulfides (LiPSs) and sluggish redox kinetics of sulfur species. Herein, a series of ultrathin single-atomic tungsten-doped Co3O4 (Wx-Co3O4) nanosheets as catalytic additives in the sulfur cathode for LSBs are rationally designed and synthesized. Benefiting from the enhanced catalytic activity and optimized electronic structure by W doping, the Wx-Co3O4 not only reduces the shuttling of LiPSs but also decreases the energy barrier of sulfur redox reactions of sulfur species, leading to accelerated electrode kinetic. As a result, LSB cathodes with the use of 5.0 wt% W0.02-Co3O4 as the electrocatalyst show the high reversible capacities of 1217.0 and 558.6 mAh g−1 at 0.2 and 5.0 C, respectively, and maintain a high reversible capacity of 644.6 mAh g−1 at 1.0 C (1.0 C = 1675 mA g−1) after 500 cycles. With a high sulfur loading of 5.5 mg cm−2 and electrolyte–electrode ratio of 8 μLelectrolyte mgsulfur−1, the 5.0 wt% W0.02-Co3O4-based sulfur cathode also retains a high reversible areal capacity of 3.86 mAh cm−2 at 0.1 C after 50 cycles with an initial capacity retention of 84.7%

Dual-Phase Transformation: Spontaneous Self-Template Surface-Patterning Strategy for Ultra-transparent VO₂ Solar Modulating Coatings

Dual-phase transformation has been developed as a template-free surface patterning technique in this study. Ordered VO₂ honeycomb structures with a complex hierarchy have been fabricated <i>via</i> this method, and the microstructures of the obtained VO₂(M) coatings are tunable by tailoring the pertinent variables. The VO₂(M) honeycomb-structured coatings have excellent visible light transmittance at 700 nm (<i>T</i>_vis) up to 95.4% with decent solar modulating ability (Δ<i>T</i>_sol) of 5.5%, creating the potential as ultratransparent smart solar modulating coatings. Its excellent performance has been confirmed by a proof-of-principle demonstration. The dual-phase transformation technique has dramatically simplified the conventional colloidal lithography technique as a scalable surface patterning technique for achieving high-performance metal oxide coatings with diverse applications, such as catalysis, sensing, optics, electronics, and superwettable materials