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For towering structures under complex time-varying excitation, the tuned magnetic fluid rolling-ball dampers (TMFRBD) cannot achieve self-tuning damping. In this paper, considering the operating characteristics of the TMFRBD, a damper self-tuning control algorithm, namely particle swarm optimization (PSO)-FUZZY-PID, is proposed for real-time adjustment of the intrinsic frequency of TMFRBD, which can greatly improve the damping effect, namely self-tuning magnetic fluid rolling-ball dampers (STMFRBD). Firstly, the equivalent dynamics model of the damping system is established, deriving the structural dynamic amplitude response as a function of the excitation frequency to structural frequency ratio. Different frequency tracking schemes of the damper are compared and analyzed. Then magnetic field simulations and magnetic fluid magnetic property measurements are performed for the dampers, respectively. Secondly, the self-tuning PSO-FUZZY-PID control algorithm is designed to improve the damping performance of STMFRBD under time-varying excitation by optimizing factors of the FUZZY-PID controller with PSO. To confirm the effectiveness of the damper self-tuning control algorithm, the frequency tracking of dampers with different control algorithms under time-varying excitation is compared. The results show that the damper’s frequency can be tuned quickly and accurately tracking excitation frequency by PSO-FUZZY-PID. Finally, the simulation and experimental results of STMFRBD and passive mass damper (PMD) under different loads are analyzed, and the structural amplitude response is analyzed using the Hilbert-Huang transform (HHT). In addition, the damping of STMFBD and TMFBD under different loads is compared. The results show that STMFRBD has better vibration-damping performance than PMD and TMFRBD.

Background Botrytis cinerea is a serious plant fungus and strongly affects the yield and quality of crops, and its main control strategy is the employment of fungicides. To research for efficient fungicide with novel structure, a series of novel benzimidazole derivatives bearing pyrimidine and thioether moieties were designed and synthesized. Results Some target compounds such as 4 h, 4i, 4 k, 4 L, 4 m, 4 s, 4 t and 4u exhibited notable fungicidal activities, with EC50 values in the range of 0.13-0.24 μg mL-1 , which means that their activities were comparable or higher than that of carbendazim (EC50 , 0.21 μg mL-1 ). Among them, N-(4-fluorophenyl)-2-((4-(1H-benzimidazol-2-yl)-6-(4-methoxyphenyl) pyrimidin-2-yl)thio)acetamide (4 m) displayed the best activity (EC50 , 0.13 μg mL-1 ). Molecular electrostatic potential analysis of 4 m elucidated that the NH moiety of benzimidazole ring was located in the positive potential region and may generate hydrogen bond with target amino acid residue. Molecular docking analysis revealed that there were one hydrogen bond and one 𝜋-𝜋 interaction between 4 m and target protein. Conclusions This study demonstrated that the benzimidazole derivatives bearing pyrimidine and thioether moieties can be further optimized as a lead compound for the control of B. cinerea. The combination of molecular electrostatic potential and molecular docking analyses may provide a valuable reference for studying the interaction between the ligand and target protein. This article is protected by copyright. All rights reserved.

With the aim of exploring new benzimidazole derivative with high fungicidal activity, a series of novel 2-(2-(alkylthio)-6-phenylpyrimidin-4-yl)-1H-benzimidazoles were designed and synthesized, and their in vitro fungicidal activities were evaluated. Compounds 5a, 5f, 5g, 5h, 5i and 5l exhibited excellent fungicidal activities against Botrytis cinerea, and 5c, 5f, 5h, 5i and 5l displayed notable fungicidal activities against Sclerotinia sclerotiorum. Among them, compound 5i (R1 = fluorine, R2 = benzyl) displayed the best activity towards the two tested fungi. Docking study of 5i with β-tubulin protein revealed that the NH moiety of benzimidazole ring generated a hydrogen bond with Gln-11 residue, and the fluorine atom of benzene ring formed a hydrogen bond with Tyr-208 residue, respectively; the benzene ring of Tyr-222 and the pyrimidine ring of 5i yielded a π-π interaction. The molecular electrostatic potential analysis elucidated the nitrogen atom of benzimidazole ring, fluorine atom of benzene ring and sulfur atom of thioether moiety were located in the negative potential regions, whereas some hydrogen atoms of benzene, benzimidazole and pyrimidine rings were located in the positive potential regions. This analysis demonstrated the reason why 5i can form hydrogen bonds with amino acid residues of target protein.

Tremendous progress has been made in boosting the realization of magnetoelectric (ME) magnetometers based on the direct ME effect (DME) for bulk ME laminates. In this work, we studied the potential of an electrically driven bulk magnetic field sensor based on the converse ME effect (CME). Starting from a discussion about the dependence of the induced voltage from the pickup coil on coil parameters and the CME coupling process, we then experimentally measured the optimized bias field in the off resonance region and observed the double-peak phenomenon that occurred within the resonance window. More importantly, the optimization with respect to the sample's dimension, excitation voltage, and frequency was conducted to improve the sensing capability for low-frequency magnetic fields. It was experimentally found that a limit of detection (LoD) of ∼115 pT for a magnetic field of 10 Hz and ∼300 pT for a magnetic field of 1 Hz was achieved when exciting the ME laminate at 1 V without any bias field. In this case, the power consumption for the ME laminate is only 0.56 mW, which is much lower compared to tens of milliwatts (10–100 mW) for optically pumped or flux gate sensors (excluding the power consumption from the electronics) and also shows advantages over conventional ME magnetic field sensors based on DME with a current pump.