56 research outputs found

    Alchemical and structural distribution based representation for improved QML

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    We introduce a representation of any atom in any chemical environment for the generation of efficient quantum machine learning (QML) models of common electronic ground-state properties. The representation is based on scaled distribution functions explicitly accounting for elemental and structural degrees of freedom. Resulting QML models afford very favorable learning curves for properties of out-of-sample systems including organic molecules, non-covalently bonded protein side-chains, (H2_2O)40_{40}-clusters, as well as diverse crystals. The elemental components help to lower the learning curves, and, through interpolation across the periodic table, even enable "alchemical extrapolation" to covalent bonding between elements not part of training, as evinced for single, double, and triple bonds among main-group elements

    High Efficient Photodegradation and Photocatalytic Hydrogen Production of CdS/BiVO<sub>4</sub> Heterostructure through <i>Z</i>‑Scheme Process

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    Novel heterostructured CdS/BiVO<sub>4</sub> nanocomposites were fabricated in a low-temperature water bath system. The uniform CdS nanoparticles with an average size of 20 nm were homogeneously interspersed on BiVO<sub>4</sub> nanosheets. The coupling of BiVO<sub>4</sub> and CdS nanoparticles could notably promote the photocatalytic activity. The composites reached a high H<sub>2</sub>-production rate of 0.57 mmol h<sup>–1</sup> under visible light irradiation, about 5.18 times higher than that of pure CdS nanoparticles. The dominant active species in the photocatalytic system were also confirmed by the radical trapping test. Based on the calculation and experimental results, a <i>Z</i>-scheme photocatalytic mechanism was proposed, which was further confirmed by the electrochemical impedance spectroscopy and the cycling test. The <i>Z</i>-scheme photocatalytic system endows the CdS/BiVO<sub>4</sub> heterostructure with strong reducibility and oxidizability and excellent stability

    Synthesis, Photocatalytic and Electrocatalytic Activities of Wormlike GdFeO<sub>3</sub> Nanoparticles by a Glycol-Assisted Sol–Gel Process

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    Wormlike GdFeO<sub>3</sub> (GFO) nanoparticles were synthesized by a glycol-assisted sol–gel rapid calcination process. The as-synthesized GdFeO<sub>3</sub> was characterized by X-ray diffraction, transmission electron microscopy, differential scanning calorimeter and thermogravimetric analysis, Fourier transformed infrared spectroscopy, and UV–vis absorption spectroscopy. The visible-light-responsive photocatalytic activity of GdFeO<sub>3</sub> nanoparticles was evaluated by the photodegradation of Rhodamine B under visible light. The synergism of semiconductor-photocatalyzed oxidation and heterogeneous photo-Fenton-like reaction can markedly promote the photodegradation with a booming catalytic activity (<i>k</i> = 1.2814 h<sup>–1</sup>). Compared with the bulk, the catalytic activity of the GFO–H<sub>2</sub>O<sub>2</sub> system was improved about 80 times. Meanwhile, the glass carbon electrode decorated with the resulting nanoparticles was used to examine the electrocatalytic behavior for <i>p</i>-nitrophenol reduction in a basic solution. The results show the obtained GdFeO<sub>3</sub> nanoparticles with excellent photocatalytic and electrocatalytic activities

    A Scheme to Optimize Flow Routing and Polling Switch Selection of Software Defined Networks

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    <div><p>This paper aims at minimizing the communication cost for collecting flow information in Software Defined Networks (SDN). Since flow-based information collecting method requires too much communication cost, and switch-based method proposed recently cannot benefit from controlling flow routing, jointly optimize flow routing and polling switch selection is proposed to reduce the communication cost. To this end, joint optimization problem is formulated as an Integer Linear Programming (ILP) model firstly. Since the ILP model is intractable in large size network, we also design an optimal algorithm for the multi-rooted tree topology and an efficient heuristic algorithm for general topology. According to extensive simulations, it is found that our method can save up to 55.76% communication cost compared with the state-of-the-art switch-based scheme.</p></div

    Image_2_Genome-Wide Characterization of Endogenous Retroviruses in Bombyx mori Reveals the Relatives and Activity of env Genes.TIF

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    <p>Endogenous retroviruses (ERVs) are retroviral sequences that remain fixed in the host genome, where they could play an important role. Some ERVs have been identified in insects and proven to have infectious properties. However, no information is available regarding Bombyx mori ERVs (BmERVs) to date. Here, we systematically identified 256 potential BmERVs in the silkworm genome via a whole-genome approach. BmERVs were relatively evenly distributed across each of the chromosomes and accounted for about 25% of the silkworm genome. All BmERVs were classified as young ERVs, with insertion times estimated to be less than 10 million years. Seven BmERVs possessing the env genes were identified. With the exception of the Orf133 Helicoverpa armigera nuclear polyhedrosis virus, the env sequences of BmERVs were distantly related to genes encoding F (Fa and Fb) and GP64 proteins from Group I and Group II NPVs. In addition, only the amino acid sequence of the BmERV-21 envelope protein shared a similar putative furin-like cleavage site and fusion peptide with Group II baculoviruses. All of the env genes in the seven BmERVs were verified to exist in the genome and be expressed in the midgut and fat bodies, which suggest that BmERVs might play an important role in the host biology.</p
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