A New Strategy in Boosting Information Spread.

Finding a seed set to propagate more information within a specific budget is defined as the influence maximization (IM) problem. The traditional IM model contains two cardinal aspects: (i) the influence propagation model and (ii) effective/efficient seed-seeking algorithms. However, most of models only consider one kind of node (i.e., influential nodes), ignoring the role of other nodes (e.g., boosting nodes) in the spreading process, which are irrational. Specifically, in the real-world propagation scenario, the boosting nodes always improve the spread of influence from the initial activated seeds, which is an efficient and cost-economic measure. In this paper, we consider the realistic budgeted influence maximization (RBIM) problem, which contains two kind of nodes to improve the diffusion of influence. Facing the newly modified objective function, we propose a novel B-degree discount algorithm to solve it. The novel B-degree discount algorithm which adopts the cost-economic boosting nodes to retweet the influence from the predecessor nodes can greatly reduce the cost, and performs better than other state-of-the-art algorithms in both effect and efficiency on RBIM problem solving.

P2-Type Na0.67Ni0.23Mg0.1Mn0.67O2 as a High-Performance Cathode for a Sodium-Ion Battery.

There is intense interest in sodium-ion batteries as an alternative to lithium-ion batteries for electric storage applications because of the low-cost and abundant sodium resources. Na0.67Ni0.33-xMgxMn0.67O2 compounds (x = 0, 0.02, 0.05, 0.1, or 0.15) were prepared by a sol-gel method and used as a cathode for sodium-ion batteries. The X-ray powder diffraction measurements demonstrated that the obtained samples have a pure P2 phase. Na0.67Ni0.23Mg0.1Mn0.67O2 delivers an initial reversible capacity of 105 mAh g(-1) in the potential region from 2.0 to 4.5 V at a charge/discharge current density of 48 mA g(-1). Moreover, the cyclability is improved by doping Mg. The capacity of Na0.67Ni0.23Mg0.1Mn0.67O2 can remain at approximately 84.9 mAh g(-1) at a current density of 48 mA g(-1) after 100 cycles. The improved high rate performance of Na0.67Ni0.23Mg0.1Mn0.67O2 was attributed to the increased lattice parameters and d spacing of the Na(+) layer. Therefore, Mg-doped Na0.67Ni0.23Mg0.1Mn0.67O2 is a promising cathode for sodium-ion batteries with excellent rate and cyclic performance.

Dynamic Octahedral Breathing in Oxygen-Deficient Ba(0.9)Co(0.7)Fe(0.2)Nb(0.1)O(3-δ) Perovskite Performing as a Cathode in Intermediate-Temperature SOFC.

Ba(0.9)Co(0.7)Fe(0.2)Nb(0.1)O(3-δ) outperforms as a cathode in solid-oxide fuel cells (SOFC), at temperatures as low as 700-750 °C. The microscopical reason for this performance was investigated by temperature-dependent neutron powder diffraction (NPD) experiments. In the temperature range of 25-800 °C, Ba(0.9)Co(0.7)Fe(0.2)Nb(0.1)O(3-δ) shows a perfectly cubic structure (a = a0), with a significant oxygen deficiency in a single oxygen site, that substantially increases at the working temperatures of a SOFC. The anisotropic thermal motion of oxygen atoms considerably rises with T, reaching B(eq) ≈ 5 Å(2) at 800 °C, with prolate cigar-shaped, anisotropic vibration ellipsoids that suggest a dynamic breathing of the octahedra as oxygen ions diffuse across the structure by a vacancies mechanism, thus implying a significant ionic mobility that could be described as a molten oxygen sublattice. The test cell with a La(0.8)Sr(0.2)Ga(0.83)Mg(0.17)O(3-δ) electrolyte (∼300 µm in thickness)-supported configuration yields a peak power density of 0.20 and 0.40 W cm(-2) at temperatures of 700 and 750 °C, respectively, with pure H2 as fuel and ambient air as oxidant. The electrochemical impedance spectra (EIS) evolution with time of the symmetric cathode fuel cell measured at 750 °C shows that the Ba(0.9)Co(0.7)Fe(0.2)Nb(0.1)O(3-δ) cathode possesses a superior ORR catalytic activity and long-term stability. The mixed electronic-ionic conduction properties of Ba(0.9)Co(0.7)Fe(0.2)Nb(0.1)O(3-δ) account for its good performance as an oxygen-reduction catalyst.

Novel Photoanode for Dye-Sensitized Solar Cells with Enhanced Light-Harvesting and Electron-Collection Efficiency.

A novel photoanode structure modified by porous flowerlike CeO2 microspheres as a scattering layer with a thin TiO2 film deposited by atomic layer deposition (ALD) is prepared to achieve a significantly enhanced performance of dye-sensitized solar cells (DSSCs). The light scattering capability of the photoanode with the porous CeO2 microsphere layer is considerably improved. The interconnection of particles and electrical contact between bilayer and conducting substrate is further enhanced by an ALD-deposited TiO2 film, which effectively reduces the electron recombination and facilitates electron transport and thus enhances the charge collection efficiency of DSSCs. As a result, the overall efficiency of the obtained TiO2-CeO2-based cells reaches 9.86%, which is 31% higher than that of the DSSCs with a conventional TiO2 photoanode.

A Safe High-Performance All-Solid-State Lithium-Vanadium Battery with a Freestanding V2O5 Nanowire Composite Paper Cathode.

The electronic conductivity and structural stability are still challenges for vanadium pentoxide (V2O5) as cathode materials in batteries. Here, we report a V2O5 nanowire-reduced graphene oxide (rGO) composite paper for direct use as a cathode without any additives for high-temperature and high-safety solid polymer electrolyte [PEO-MIL-53(Al)-LiTFSI] lithium-vanadium batteries. The batteries can show a fast and stable lithium-ion-storage performance in a wide voltage window of 1.0-4.0 V versus Li+/Li at 80 °C, in which with an average capacity of 329.2 mAh g-1 at 17 mA g-1 and a stable cycling performance over 40 cycles are achieved. The excellent electrochemical performance is mainly ascribed to integration of the electronic conductivity of rGO and interconnected networks of the V2O5 nanowires and solid electrolyte. This is a promising lithium battery for flexible and highly safe energy-storage devices.