Coupling of Metallic VSe2 and Conductive Polypyrrole for Boosted Sodium-Ion Storage by Reinforced Conductivity Within and Outside.

Although transitional metal dichalcogenides have been regarded as appealing electrodes for sodium/potassium-ion batteries (SIBs/PIBs) owing to their high theoretical capacity, it is a key challenge to realize dichalcogenide anodes with long-period cycling performance and high-rate capability because of their poor conductivity and large volumetric change. Herein, polypyrrole-encapsulated VSe2 nanoplates (VSe2@PPy) were prepared by the selenization of VOOH hollow nanospheres and subsequent in situ polymerization and coating by pyrrole. Benefiting from the inherent metallicity of VSe2, the improvement in the conductivity and the structural protection provided by the PPy layer, the VSe2@PPy nanoplates exhibited enhanced sodium/potassium-storage performances, delivering a superior rate capability with a capacity of 260.0 mA h g-1 at 10 A g-1 in SIBs and 148.6 mA h g-1 at 5 A g-1 in PIBs, as well as revealing an ultrastability in cycling of 324.6 mA h g-1 after 2800 cycles at 4 A g-1 in SIBs. Moreover, the insertion and conversion mechanisms of VSe2@PPy in SIBs with intermediates of Na0.6VSe2, NaVSe2, and VSe were elucidated by in situ/ex situ X-ray diffraction combined with ex situ transmission electron microscopy observation and in situ potentio-electrochemical impedance spectroscopy during the sodiation and desodiation processes. Density functional theory calculations show that the strong coupling between VSe2 and PPy not only causes it to have a stronger total density of states and a built-in electric field, leading to an increased electrical conductivity, but also effectively decreases the ion diffusion barrier.

Heterojunction-Promoted Sodium Ion Storage of Bimetallic Selenides Encapsulated in a Carbon Sheath with Boosted Ion Diffusion and Stable Structure.

Although metallic chalcogenides are deemed as attractive sodium anode materials recently, the electrochemical performance is severely confined by the liability of structural collapse and sluggish ion diffusion kinetics. Herein a composite of carbon-encapsulated bimetallic selenides MoSe2-Sb2Se3 was prepared by a hydrothermal method on the basis of abundant reaction sites, high activity, an extra built-in electric field generated from heterointerfaces, and synergistic effects between the different components. Equally important, the carbon coating is effective to support the structural stability by restraining the vast volumetric variation to achieve the purpose of improving the cycling performance. The density functional theory calculation results indicate that the band gap is narrowed and that the work function is decreased on the interface of the MoSe2-Sb2Se3 heterojunction, leading to an additional driving force stemming from the introduction of the built-in electric field and the formation of the Sb-Se (Se from MoSe2) bond. Therefore, the resultant composite presents increased reaction kinetics and good electrochemical properties by acquiring a capacity of 376.0 mA h g-1 over 580 cycles at 2.0 A g-1 for the half-cell and 276 mA h g-1 over 750 cycles at 2 A g-1 for the full-cell. This work highlights bimetallic selenides with facilitated ion transferability with high performance.

Fast Approximation of Coherence for Second-Order Noisy Consensus Networks.

It has been recently established that for second-order consensus dynamics with additive noise, the performance measures, including the vertex coherence and network coherence defined, respectively, as the steady-state variance of the deviation of each vertex state from the average and the average steady-state variance of the system, are closely related to the biharmonic distances. However, direct computation of biharmonic distances is computationally infeasible for huge networks with millions of vertices. In this article, leveraging the implicit fact that both vertex and network coherence can be expressed in terms of the diagonal entries of pseudoinverse L2† of the square of graph Laplacian, we develop a nearly linear-time algorithm to approximate all diagonal entries of L2† , which has a theoretically guaranteed error for each diagonal entry. The key ingredient of our approximation algorithm is an integration of the Johnson-Lindenstrauss lemma and Laplacian solvers. Extensive numerical experiments on real-life and model networks are presented, which indicate that our approximation algorithm is both efficient and accurate and is scalable to large-scale networks with millions of vertices.

Minimal TiO2 Coupled with Conductive Polymer-Stimulated Synergistic Effect on Fast and Reversible Sodium-Ion Storage for Bismuth Sulfide.

Designing multiphase composition is believed to availably boost the structural integrity and electrochemical properties of sodium-ion battery anodes. Herein, a conceive of nanoflowers, assembled with Bi2S3 nanorods, is demonstrated to construct the multiphase composition involving TiO2 coating and polypyrrole (PPy) encapsulation. Bi2S3 acted as the dominating active material, in consideration of the low content of TiO2, which ensured the high capacity of the composite. The dual-structural restrain of the TiO2 and PPy coatings can effectively alleviate volume variation based on the pseudo-"zero-strain" effect of TiO2 and high flexibility of PPy shells. Meanwhile, the heterointerface greatly enhanced the coupling effect between Bi2S3 and TiO2 and thus improved the electrochemical performance, which was proved by the results of density functional theory calculation and electrochemical tests. Combining the regulation from the Bi2S3/TiO2 heterojunction and the dual-structural restrain effect, the Bi2S3/TiO2@PPy electrode exhibited excellent rate performance and superior cycle stability (275.8 mA h g-1 over 500 cycles at 10 A g-1). This study indicates that designing multiphase composition can be very promising and provides a structural insight to construct high stability in electrodes for sodium-ion batteries.

The water extract of "Jiao Mei Gu" attenuates the lipopolysaccharide-induced inflammatory response via inhibiting NF-κB activity in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Jiao Mei Gu (JMG), Cayratia albifolia C.L.Li, is a type of Dong plant widely growing in Dong autonomous counties, Hunan province, China. As a type of traditional herbal medicine, the root of JMG plant has been used to treat inflammatory-related diseases such as arthritis because of its prominent anti-inflammatory effects in Dong medicine. AIM OF THE STUDY: This work investigated the anti-inflammatory effects and mechanisms of the water extract from the root of JMG on lipopolysaccharide (LPS)-induced inflammatory models. METHODS: Endotoxemia was induced in C57BL/6 mice by intraperitoneal injection of LPS (20 mg/kg), meanwhile intraperitoneal administration of safe doses of JMG. The survival curve of mice was determined. Serum inflammatory cytokines were detected by the Bio-Plex Mouse Cytokine 23-Plex Panel Kit and enzyme-linked immunosorbent assay (ELISA) at 6 h after drug treatment. Hematoxylin-eosin (HE) staining of important organs was completed at 24 h after treatment. The mechanism of inflammatory action was investigated in vitro on LPS-stimulated macrophages. Macrophage inflammation was then induced using 10 µg/mL LPS. The anti-inflammatory effect of JMG was investigated by the quantitative polymerase chain reaction (qPCR) and ELISA. The anti-inflammatory mechanism was determined using western blotting, the electrophoretic mobility shift assay, and immunocytochemistry. Finally, the antimicrobial activity of JMG was verified by survival experiments in vivo and by bacterial culture experiments in vitro. RESULTS: A 200 mg/kg water extract of JMG was safe for mice and had a significant protective effect on LPS-induced sepsis. Organ damage of heart, liver, lung and kidney was also significantly reduced at 24 h in the JMG group, when compared with the LPS group. The serum MIP-1α (CCL-3), MIP-1ß (CCL-4), IL-1ß, and TNFα cytokines were significantly decreased at 6 h in the JMG group, when compared with the LPS group. In a similar manner, 0.2µg/ml JMG significantly reduced mRNA and protein levels of MIP-1α (CCL-3), MIP-1ß (CCL-4), IL-1ß, and TNFα in LPS-stimulated macrophage. JMG treatment inhibited the phosphorylation of NF-κB p65 and reduced nuclear transduction, thus reducing transcriptional activity. At the same time, we showed that JMG had no protective effect on Escherichia coli-induced sepsis, as well as no antimicrobial activity. CONCLUSIONS: Our results showed that a water-soluble extract of JMG inhibited LPS-induced inflammation via attenuating the NF-κB signaling pathway, which provides an important rationale for the treatment of inflammation-related diseases.

Scale-Free Loopy Structure is Resistant to Noise in Consensus Dynamics in Complex Networks.

The vast majority of real-world networks are scale-free, loopy, and sparse, with a power-law degree distribution and a constant average degree. In this paper, we study first-order consensus dynamics in binary scale-free networks, where vertices are subject to white noise. We focus on the coherence of networks characterized in terms of the H 2 -norm, which quantifies how closely the agents track the consensus value. We first provide a lower bound of coherence of a network in terms of its average degree, which is independent of the network order. We then study the coherence of some sparse, scale-free real-world networks, which approaches a constant. We also study numerically the coherence of Barabási-Albert networks and high-dimensional random Apollonian networks, which also converges to a constant when the networks grow. Finally, based on the connection of coherence and the Kirchhoff index, we study analytically the coherence of two deterministically growing sparse networks and obtain the exact expressions, which tend to small constants. Our results indicate that the effect of noise on the consensus dynamics in power-law networks is negligible. We argue that scale-free topology, together with loopy structure, is responsible for the strong robustness with respect to noisy consensus dynamics in power-law networks.

Consensus in Self-Similar Hierarchical Graphs and Sierpinski Graphs: Convergence Speed, Delay Robustness, and Coherence.

The hierarchical graphs and Sierpinski graphs are constructed iteratively, which have the same number of vertices and edges at any iteration, but exhibit quite different structural properties: the hierarchical graphs are nonfractal and small-world, while the Sierpinski graphs are fractal and "large-world." Both graphs have found broad applications. In this paper, we study consensus problems in hierarchical graphs and Sierpinski graphs, focusing on three important quantities of consensus problems, that is, convergence speed, delay robustness, and coherence for first-order (and second-order) dynamics, which are, respectively, determined by algebraic connectivity, maximum eigenvalue, and sum of reciprocal (and square of reciprocal) of each nonzero eigenvalue of Laplacian matrix. For both graphs, based on the explicit recursive relation of eigenvalues at two successive iterations, we evaluate the second smallest eigenvalue, as well as the largest eigenvalue, and obtain the closed-form solutions to the sum of reciprocals (and square of reciprocals) of all nonzero eigenvalues. We also compare our obtained results for consensus problems on both graphs and show that they differ in all quantities concerned, which is due to the marked difference of their topological structures.

[Effects of terlipressin on blood pressure and survival in septic mice following trauma and its mechanism].

OBJECTIVE: To investigate the effects of terlipressin (TP) on blood pressure and survival in septic mice following trauma and its mechanism. METHODS: (1) Survival experiment: 120 male C57BL/6 mice aged 6-8 weeks were enrolled, the posttraumatic sepsis mice model was reproduced by traumatic hemorrhage (bilateral femoral fracture + 45% of total blood loss) followed by cecal ligation and puncture (CLP) after 8 hours. Intraperitoneal injection of TP was used for intervention. Sixty model mice were used to observe the effect of 0.05 µg/g TP at different intervention times (the drug was given immediately after traumatic hemorrhage + the administration was repeated after 6 hours, the drug was given immediately after traumatic hemorrhage + the administration was repeated every 6 hours until the end of the experiment, the drug was given at 4 hours after CLP + the administration was repeated every 6 hours until the end of the experiment) on 48-hour cumulative survival rate of mice with posttraumatic sepsis for finding the best intervention time of TP. The other 60 model mice were used to observe the effect of different TP intervention doses (0.01, 0.05, 0.25 µg/g) at the best intervention time on the 48-hour cumulative survival rate of mice with posttraumatic sepsis for finding the best intervention dose of TP. (2) Intervention experiment: the other 45 mice were enrolled, and they were randomly divided into traumatic hemorrhage + sham group (TH+sham group, only laparotomy without CLP), TH+CLP group, and TH+CLP+TP group (the best intervention time and dose of TP shown by survival experiment were used), with 15 mice in each group. Mean arterial pressure (MAP) of mice was monitored continuously. The orbital whole blood was collected at 2 hours after successful reproduction of the model, and the lung tissues were harvested at 12 hours and 24 hours, respectively. The pathological changes in lung tissue were observed with light microscope. The contents of interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α) in serum and lung tissue were determined by enzyme linked immunosorbent assay (ELISA). The expressions of IL-1ß and TNF-α mRNA in lung tissue were determined by real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The expressions of nuclear factor-κB p65 (NF-κB p65) in the nucleus and cytoplasm of lung tissue were determined by Western Blot. RESULTS: (1) Survival experiment results showed that the 48-hour cumulative survival rate of mice was highest with TP intervention by 0.05 µg/g administration immediately after traumatic hemorrhage and repeated every 6 hours, which was the best intervention method of TP. (2) Intervention experiment results showed that the pulmonary alveolar wall fracture accompanied by inflammatory cell infiltration was found at 12 hours after the successful reproduction of traumatic sepsis model, and the pathological damage was gradually increased with time prolongation. MAP was decreased sharply after traumatic hemorrhage, and it was continued to decrease after two-hit of CLP. The contents of IL-1ß and TNF-α in serum and lung tissue, the expressions of IL-1ß and TNF-α mRNA in lung tissue, and expressions of NF-κB p65 protein in cytoplasm and nucleus of TH+CLP group were significantly higher than those in TH+sham group. Compared with TH+CLP group, the pathological changes in lung tissue were improved significantly, and the MAP was decreased gently after TP intervention, the levels of inflammatory mediators in serum were significantly decreased [IL-1ß (pg/L): 164.32±25.25 vs. 233.11±23.02, TNF-α (pg/L): 155.56±31.47 vs. 596.38±91.50, both P < 0.05], and their expressions in lung tissue [IL-1ß content (ng/mg): 262.68±16.56 vs. 408.15±17.85, IL-1ß mRNA (2-Δ ΔCt): 2.63±0.68 vs. 6.22±0.74; TNF-α content (ng/mg): 311.07±17.35 vs. 405.04±24.83, TNF-α mRNA (2-Δ ΔCt): 2.04±0.62 vs. 5.32±0.55, all P < 0.01], and NF-κB p65 protein expressions were significantly down-regulated (gray value: 0.47±0.01 vs. 1.28±0.05 in cytoplasm, 0.45±0.02 vs. 1.95±0.06 in nucleus, both P < 0.01]. CONCLUSIONS: The continuous intervention with TP 0.05 µg/g administration immediately after traumatic hemorrhage and repeated every 6 hours could improve the MAP of mice with traumatic sepsis, and improve the prognosis. The mechanism may be related to alleviating the inflammatory response and inhibiting the activation of the NF-κB signaling pathway in the lung tissue.

Spectra of weighted scale-free networks.

Much information about the structure and dynamics of a network is encoded in the eigenvalues of its transition matrix. In this paper, we present a first study on the transition matrix of a family of weight driven networks, whose degree, strength, and edge weight obey power-law distributions, as observed in diverse real networks. We analytically obtain all the eigenvalues, as well as their multiplicities. We then apply the obtained eigenvalues to derive a closed-form expression for the random target access time for biased random walks occurring on the studied weighted networks. Moreover, using the connection between the eigenvalues of the transition matrix of a network and its weighted spanning trees, we validate the obtained eigenvalues and their multiplicities. We show that the power-law weight distribution has a strong effect on the behavior of random walks.

Anomalous behavior of trapping in extended dendrimers with a perfect trap.

Compact and extended dendrimers are two important classes of dendritic polymers. The impact of the underlying structure of compact dendrimers on dynamical processes has been much studied, yet the relation between the dynamical and structural properties of extended dendrimers remains not well understood. In this paper, we study the trapping problem in extended dendrimers with generation-dependent segment lengths, which is different from that of compact dendrimers where the length of the linear segments is fixed. We first consider a particular case that the deep trap is located at the central node, and derive an exact formula for the average trapping time (ATT) defined as the average of the source-to-trap mean first passage time over all starting points. Then, using the obtained result we deduce a closed-form expression for the ATT to an arbitrary trap node, based on which we further obtain an explicit solution to the ATT corresponding to the trapping issue with the trap uniformly distributed in the polymer systems. We show that the trap location has a substantial influence on the trapping efficiency measured by the ATT, which increases with the shortest distance from the trap to the central node, a phenomenon similar to that for compact dendrimers. In contrast to this resemblance, the leading terms of ATTs for the three trapping problems differ drastically between extended and compact dendrimers, with the trapping processes in the extended dendrimers being less efficient than in compact dendrimers.