Search

Antibiotics have been heavily used over the past decades, resulting in their frequent detections in rivers and increasing ecological risks. Recognizing characteristics of antibiotic ecological risks (AERs) and making effective strategies to mitigate the AERs are essential to ensure the safety of aquatic ecosystem and public health. In this study, an integrated technological framework has been proposed toward identifying management options for reducing AERs by jointly utilizing multimedia fugacity modelling and ecotoxicological risk assessment, and applied to characterize the AERs in a peri-urban river in Beijing. Specifically, a level III fugacity model has been successfully established to simulate the fate of antibiotics in the environment, and the manageable parameters have been screened out via sensitivity analysis of the model. Then the validated fugacity model has been used for scenario modellings to optimize mitigation strategies of AERs. Results show most of the antibiotics considered are frequently detected in the river, and pose medium or high risks to aquatic organisms. Relatively, the macrolides and fluoroquinolones present higher ecotoxicological risks than sulfonamides and tetracyclines. Furthermore, the mixture risk quotient and predictive equation of concentration addition suggest joint and synergistic/antagonistic effects of AERs for multiple or binary antibiotics in the environment. Largely, the concentrations of antibiotics in the river are determined by the source emissions into water and soil. Scenario modellings show the improvement of antibiotic removal rates would be considered preferentially to mitigate the AERs. Also, controlling human consumption is conducive to reducing the risks posed by tetracyclines, macrolides and trimethoprim, while controlling animal consumption would benefit the reduction for sulfonamides. Overall, the joint strategy presents the greatest reduction of AERs by reducing antibiotic consumption and together improving sewage treatment rate and antibiotic removal rate. The study provides us a useful guideline to make ecological risk-based mitigation strategy for reducing AERs in environment. • A framework was proposed toward identifying ecological risk-based mitigation strategy. • The sixteen antibiotics were widely detected in the river and posed medium or high risks. • The constructed fugacity model could be successfully used for predicting antibiotics. • Improvement of antibiotic removal rate would be considered preferentially to mitigate the AERs. • Controlling consumption was conducive to reducing the AERs. [ABSTRACT FROM AUTHOR]

Piezoelectric material-actuated so-called solid-state (i.e., mechanism-free) ornithopters do not need conventional motors and mechanisms, potentially saving weight and energy consumption, reducing mechanical complexity, and improving wing flexibility. In solid-state ornithopters, wing flapping can be achieved by surface-mounted piezoelectric actuators. The design of a solid-state ornithopter is a complex multi-disciplinary task, and optimization of wing topology, actuator placement, and excitation parameters requires a computationally efficient model to predict its dynamic response and performance metrics. In this paper, effectively, a novel flight simulation model is presented based on a reduced-order lumped parameter multi-body model coupled with a vortex lattice program. The proposed lumped parameter model can be represented by an equivalent multi-body mechanical model or a circuit model. The coupling considered in the lumped parameter model includes: (1) the body-wing momentum interaction, (2) bend–twist​ coupling of the piezocomposite wings, (3) fluid–structure interactions between the flapping wings, oscillating body, and the ambient fluid, and (4) electromechanical coupling between a resistive–inductive–capacitive driving circuit and the piezocomposite wings. The wing motion is described using the Rayleigh–Ritz method, in which the representative wing modes are identified as spanwise plunge, chordwise curvature, and twist. The body-wing interaction is modeled using Hamilton's principle. The fluid-induced effects on the wings have three contributions: added mass and damping, quasi-steady aerodynamic forces obtained using the vortex lattice program, and unsteady aerodynamic forces calculated using the Theodorsen formulation, which is integrated into the wing heave and pitch degrees of freedom in the lumped parameter model. The proposed reduced-order model proposed is computationally efficient, suitable for trade studies and multi-disciplinary design optimization, and can be easily converted to state representation for controller development purposes. The capabilities of this model are demonstrated through tethered and gliding flight simulations. System properties such as circuit parameters, structural parameters, excitation frequency ratio, etc., are investigated. Phugoid and short period modes are observed in gliding flight simulations. The contribution of active flapping is found by the comparison of flight simulations with and without active flapping. A net thrust contributed by unsteady lift is demonstrated even though the thrust-lift ratio is low. The proposed model serves as an extensible framework for modeling and design optimization of ornithopters. • A coupled electromechanical-aeroelastic model is developed for mechanism-free ornithopters. • The wing-body interaction, bend–twist coupling, wing and body fluid–structure interactions, and electromechanical coupling are considered. • Using the Rayleigh–Ritz method, wing motion is decomposed into plunge and pitch motions, compatible with the Theodorsen formulation. • Phugoid and short period modes are observed in the gliding flight simulations. • A net thrust force is demonstrated due to flapping-induced unsteady lift force and body-wing coupling. [ABSTRACT FROM AUTHOR]

Lane-change trajectory planning of autonomous light trucks is closely related to safety, driving stability and transportation efficiency, especially in complex road and traffic conditions. However, the collision risk assessment and the impact of roll dynamics, which are considered as critical safety factors, are not well investigated in most of the previously proposed planning strategies. In this study, a novel lane-change trajectory planning framework for autonomous light trucks on curved roads is proposed to improve the vehicle safety, vehicle stability and transportation efficiency. To begin with, curvilinear Gaussian collision risk model considering longitudinal motion, lateral motion and short-term motion trend of surrounding vehicles is utilized to accurately establish the risk map of the traffic environment. Then, collision risk, lateral and roll dynamics are considered in the planning stage to screen out the safe and dynamic-stable trajectory candidates. Furthermore, the technique for order preference by similarity to ideal situation (TOPSIS) approach is employed to handle the multi-criteria decision-making problem by scoring and ranking the performance of the trajectory candidates and select the optimal one. Finally, compared with artificial potential field method and the planner without dynamic constraints, the experimental results validate the effectiveness and performance of the proposed planning framework through MATLAB/Simulink-TruckSim joint platform. • Curvilinear Gaussian collision risk model is utilized to establish the risk distribution map of the traffic environment. • Collision risk, lateral and roll dynamics are considered in the planning stage to optimize the trajectory. • TOPSIS algorithm is employed to solve the multi-objective optimization problem for optimal trajectory selection. [ABSTRACT FROM AUTHOR]

• First Pd@ZIF-92 nanocatalyst for efficient C(sp2)-C(sp2) cross-coupling reactions. • Post-synthetic modification of ZIF-90 to ZIF-92 and Pd@ZIF-92. • High catalytic activity and recyclability for reactions in pure water. • Environment-friendly, stable and robust nanocatalyst for cross-couplings. Herein the first ever Pd2+-decorated ZIF-92 nanostructure is readily accessed by post-synthesis modification (PSM) of the zeolitic imidazolate framework ZIF-90. Thus, the imidazolate linker of the ZIF-90 is functionalized with the hydroxyethylimino group, followed by anchoring the palladium catalytically active sites through a tight coordination of Pd2+ ions to both the N and O atoms of ZIF-92. The acquired data (by PXRD, EDS, SEM, XPS, ICP-AES) concerning the crystalline structure, elemental mapping and network configuration of the Pd@ZIF-92 catalyst confirmed its structure, before and after the cross-coupling reactions and following recycling. The Pd@ZIF-92 showed excellent catalytic activity (>99%) and chemoselectivity in Suzuki-Miyaura coupling proceeding in neat water, at very low Pd loading (0.009 mol%). Comparison of its performance with that of many reported Pd nanocatalysts operating in aqueous/protic media testifies to its superiority. The appealing gateway to this innovative, stable, robust, easily recoverable and reusable Pd@ZIF-92 nanostructure recommends its beneficial utilization in C(sp2)-C(sp2) cross-couplings and other sustainable, environmentally-friendly processes. [ABSTRACT FROM AUTHOR]