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Background: Vibrio alginolyticus is an important pathogen that has to be closely monitored and controlled in the mariculture industry for its strong pathogenicity, quick onset after infection and high mortality rate to aquatic animals. Fast, simple and specific methods are demanded for its on-site detection to effectively control its outbreaks and prevent economic losses. Detection specificity towards the pathogenic strains has to be emphasized to facilitate pointed treatment and prevention. Polymerase chain reaction (PCR) based molecular approaches have been developed, but their application is limited due to the requirement for complicated thermal cycling machines and trained personnel. Results: A fast, simple and highly specific detection method for V. alginolyticus pathogenic strains was established based on the isothermal recombinase polymerase amplification (RPA) and lateral flow dipsticks (LFD). The method targeted a virulence gene toxR that was reported to have a good coverage for the V. alginolyticus pathogenic strains. To ensure the specificity, the primer-probe set of the RPA system was carefully designed to recognize regions in gene toxR that were diverged in different Vibrio species but conserved in V. alginolyticus pathogenic strains. The primer-probe set was determined after a systematic screening on amplification performance, primer-dimer formation and false positive signals.The RPA-LFD method was confirmed to have a high specificity to V. alginolyticus pathogenic strains without any cross reaction with other Vibrio species, and was able to detect as low as 1 colony forming unit per microliter of the bacterium without DNA extraction. The method finishes detection within 30 min under the temperature between 35oC and 45oC, and the visual signal on the dipstick was directly read with naked eye. In an application simulation, randomly infected shrimp homogenate samples were 100% accurately detected. Conclusions: ​The RPA-LFD method developed in this study is fast, simple, highly specific and independent of complicated equipment. It is well applicable to the on-site detection of V. alginolyticus pathogenic strains for the mariculture industry.

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With the rapid growth of renewable energy generation, it has become essential to give a comprehensive evaluation of renewable energy integration capability in power systems to reduce renewable generation curtailment. Existing research has not considered the correlations between wind power and photovoltaic (PV) power. In this paper, temporal and spatial correlations among different renewable generations are utilized to evaluate the integration capability of power systems based on the copula model. Firstly, the temporal and spatial correlation between wind and PV power generation is analyzed. Secondly, the temporal and spatial distribution model of both wind and PV power generation output is formulated based on the copula model. Thirdly, aggregated generation output scenarios of wind and PV power are generated. Fourthly, wind and PV power scenarios are utilized in an optimal power flow calculation model of power systems. Lastly, the integration capacity of wind power and PV power is shown to be able to be evaluated by satisfying the reliability of power system operation. Simulation results of a modified IEEE RTS-24 bus system indicate that the integration capability of renewable energy generation in power systems can be comprehensively evaluated based on the temporal and spatial correlations of renewable energy generation.

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