8 research outputs found

    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

    (Pc)Eu(Pc)Eu[<i>trans</i>-T(COOCH<sub>3</sub>)<sub>2</sub>PP]/GO Hybrid Film-Based Nonenzymatic H<sub>2</sub>O<sub>2</sub> Electrochemical Sensor with Excellent Performance

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    A facile approach was developed for preparing the multilayer hybrid films of mixed (phthalocyaninato) (porphyrinato) europium­(III) triple-decker compound (Pc)­Eu­(Pc)­Eu­[<i>trans</i>-T­(COOCH<sub>3</sub>)<sub>2</sub>PP] (<b>1</b>) and graphene oxide (GO) using the solution-processing QLS method. The combination of the nature of relatively high conductivity and great surface area for GO with the electroactive and semiconductive triple-decker compound in ITO electrode renders the hybrid film excellent sensing property for H<sub>2</sub>O<sub>2</sub>, due to the optimized triple-decker molecular packing in the uniform-sized nanoparticles (ca. 70 nm) formed on the GO surface. The amperometric responses are linearly proportional to the concentration of H<sub>2</sub>O<sub>2</sub> in the range of 0.05–1800 μM with a fast response time of 0.03 s μM<sup>–1</sup>, a low detection limit of 0.017 μM, and good sensitivity of 7.4 μA mM<sup>–1</sup>. The present work represents the best result of tetrapyrrole-based nonenzymatic electrochemical sensor for H<sub>2</sub>O<sub>2</sub>. Nevertheless, the triple-decker/GO/ITO also shows excellent stability, reproducibility, and selectivity, indicating the great potential of electroactive tetrapyrrole rare earth sandwich compounds in combination with GO in the field of nonenzymatic electrochemical sensors

    Magnetically Separable CdS/ZnFe<sub>2</sub>O<sub>4</sub> Composites with Highly Efficient Photocatalytic Activity and Photostability under Visible Light

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    Novel CdS/ZnFe<sub>2</sub>O<sub>4</sub> composites were prepared through a two-step hydrothermal process. The homogeneous ZnFe<sub>2</sub>O<sub>4</sub> nanoparticles are decorated on the self-assembled CdS spheres. Compared to those of pure CdS and blank ZnFe<sub>2</sub>O<sub>4</sub>, the photocatalytic activity and stability of the magnetically separable CdS/ZnFe<sub>2</sub>O<sub>4</sub> composites are considerably increased. The results of photoluminescence and electrochemical impedance spectroscopy further validate that the performance enhancement results from the construction of heterojunction structure, leading to high charge separation efficiency. On the basis of the calculation and the trapping test, a heterojunction photocatalytic mechanism is proposed

    Distributed filtering for complex networks under multiple event-triggered transmissions within node-wise communications

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    This paper focuses on the distributed filtering and fault estimation problems for a class of complex networks, where the communications between filters at different nodes are subject to dynamic event-triggered (DET) transmissions. A filter is constructed at each node by resorting to local measurements and information from neighboring nodes and thus the developed algorithm can be carried out distributedly. Different from the clock-driven signal transmissions in traditional distributed filtering schemes, the transmissions of both state estimates and the upper bounds of filtering error covariances (FECs) between the nodes are monitored by a multiple DET strategy to reduce unnecessary burdens in the links. Under DET transmissions, an upper bound of the FEC is obtained and then minimized via parameterizing the filter recursively. Novel sufficient conditions, which are dependent on locally available information, are provided to guarantee the uniform boundedness of the FEC at each node. The proposed method is used to solve the fault estimation problem in complex networks, where the estimation error is ensured to be exponentially bounded. Some illustrative examples are employed to show the effectiveness of our algorithm

    Joint state and fault estimation of complex networks under measurement saturations and stochastic nonlinearities

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    In this paper, the joint state and fault estimation problem is investigated for a class of discrete-time complex networks with measurement saturations and stochastic nonlinearities. The difference between the actual measurement and the saturated measurement is regarded as an unknown input and the system is thus re-organized as a singular system. An appropriate estimator is designed for each node which aims to estimate the system states and the loss of the actuator effectiveness simultaneously. In the presence of measurement saturations and stochastic nonlinearities, upper bounds of the error covariances of the fault estimates are recursively obtained and then minimized. Sufficient conditions are proposed to guarantee the existence and the unbiasedness of the developed estimator. Our developed estimator design algorithm is distributed because it depends only on the local information and the information from the neighboring subsystems, thereby avoiding the usage of a center estimator. Finally, simulation results are presented to show the performance of the proposed strategy in simultaneously estimating the states and faults

    A cyberinfrastructure for community resilience assessment and visualization

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    <div><p>Disaster resilience is a major societal challenge. Cartography and GIS can contribute substantially to this research area. This paper describes a cyberinfrastructure for disaster resilience assessment and visualization for all counties in the United States. Aided by the Application Programming Interface-enabled web mapping and component-oriented web tools, the cyberinfrastructure is designed to better serve the US communities with comprehensive resilience information. The resilience assessment tool is based on the resilience inference measurement model. This web application delivers the resilience assessment tool to the users through applets. It provides an interactive tool for the users to visualize the historical natural hazards exposure and damages in the areas of their interest, compute the resilience indices, and produce on-the-fly maps and statistics. The app could serve as a useful tool for decision makers. This app won the top 10 runners-up in the Environmental Systems Research Institute (ESRI) Climate Resilience App Challenge 2014 and the top 5 in the scientific section of the ESRI Global Disaster App Challenge 2014.</p></div

    One-Pot Synthesis of Indole-3-acetic Acid Derivatives through the Cascade Tsuji–Trost Reaction and Heck Coupling

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    A practical palladium-mediated cascade Tsuji–Trost reaction/Heck coupling of N-Ts <i>o</i>-bromoanilines with 4-acetoxy-2-butenonic acid derivatives using a Pd­(OAc)<sub>2</sub>/P­(<i>o</i>-tol)<sub>3</sub>/DIPEA system is described for a straightforward synthesis of indole-3-acetic acid derivatives. This methodology was successfully applied to synthesize various substituted indole/azaindole-3-acetic acid derivatives and Almotriptan, which is a drug for the acute treatment of migraines. Moreover, a plausible cyclization mechanism has been proposed

    Resolving the Difference in Electric Potential within a Charged Macromolecule

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    The difference of the electric potential between the middle and end of polystyrenesulfonate (PSS<sup>–</sup>) chain is discovered experimentally. Using a pH-responsive fluorophore attached to these two locations on the PSS<sup>–</sup> chain, the local pH value was determined by single molecule fluorescence technique: photon counting histogram (PCH). By the observation of a very high accumulation of proton (2–3 orders of magnitude in concentration) at the vicinity of the PSS<sup>–</sup> as a result of the electrostatic attraction between the charged chain and protons, the electric potential of the PSS<sup>–</sup> chain is determined. A higher extent of counterion adsorption is discovered at the middle of the PSS<sup>–</sup> chain than the chain end. The entropy effect of the counterion adsorption is also discoveredupon the dilution of protons, previously adsorbed counterions are detached from the chain
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