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With the rapid development of drones in China, the use of multi-rotor drones for spraying chemical pesticide against pests and weeds has recently become common in agriculture. However, the downwash generated by drone rotors considerably influences the droplet deposition process by potentially causing the liquid to drift. A test analysis method was presented and a rotor rotation test bench was designed to simulate the different rotation speed of a six-rotor drone and thus study the characteristics and distribution law of the downwash velocity. An anemometer was used to measure the downwash velocity generated at different radial positions of the rotor. Results show that the downwash velocity generated by each radial position of the rotor is evenly distributed on the rotating loop and the standard deviation of the circumferential downwash velocity is less than 1 m/s. The downwash velocity along each position in the radial direction of the rotor increase first and then decrease and the 1/2 radius position of rotor blade generate the maximum downwash velocity of 10.8 m/s in the test. The downwash velocity does not considerably change with longitude, but decreases at a distance of 10 cm from the ground due to the ground effect. Therefore, the parameters of airfoil profile at each radial position on the rotors have a marked effect on the magnitude of the downwash velocity. This study provides an effective measurement method for the investigation of the downwash velocity distribution of drone rotors. The measurement results can provide a reference for the nozzle distribution under the rotor and the study of droplet movement. [ABSTRACT FROM AUTHOR]

Twenty-five novel pregnenolone/2-cyanoacryloyl conjugates ( 6 – 30 ) were designed and prepared, with the aim of developing novel anticancer drugs with dual NF-κB inhibitory and anti-proliferative activities. Compounds 22 and 27 – 30 showed inhibition against TNF-α-induced NF-κB activation in luciferase assay, which was confirmed by Western blotting. Among them, compound 30 showed potent NF-κB inhibitory activity (IC 50 = 2.5 μM) and anti-proliferative against MCF-7, A549, H157, and HL-60 cell lines (IC 50 = 6.5–36.2 μM). The present study indicated that pregnenolone/2-cyanoacryloyl conjugate I can server as a novel scaffold for developing NF-κB inhibitors and anti-proliferative agents in cancer chemotherapy. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • New IAA-tacrine hybrids were synthesized as potent dual AChE/BChE inhibitors. • This series of hybrids targeted both CAS and PAS of AChE and BChE. • Compound 5e could increase the frequency of the network oscillation. • Compound 5e could decrease the duration of synchronized firing. Abstract A series of new indole-3-acetic acid (IAA)-tacrine hybrids as dual acetylcholinesterase (AChE)/butyrylcholinesterase (BChE) inhibitors were designed and prepared based on the molecular docking mode of AChE with an IAA derivative (1a), a moderate AChE inhibitor identified by screening our compound library for anti-Alzheimer's disease (AD) drug leads. The enzyme assay results revealed that some hybrids, e.g. 5d and 5e , displayed potent dual in vitro inhibitory activities against AChE/BChE with IC 50 values in low nanomolar range. Molecular modeling studies in tandem with kinetic analysis suggest that these hybrids target both catalytic active site and peripheral anionic site of cholinesterase (ChE). Molecular dynamic simulations and Molecular Mechanics/Poisson-Boltzmann Surface Area (MM-PBSA) calculations indicate that 5e has more potent binding affinity than hit 1a , which may explain the stronger inhibitory effect of 5e on AChE. Furthermore, their predicted pharmacokinetic properties and in vitro influences on mouse brain neural network electrical activity were discussed. Taken together, compound 5e can be highlighted as a lead compound worthy of further optimization for designing new anti-AD drugs. [ABSTRACT FROM AUTHOR]