The design, hysteresis modeling and control of a novel SMA-fishing-line actuator

Fishing line can be combined with shape memory alloy (SMA) to form novel artificial muscle actuators which have low cost, are lightweight and soft. They can be applied in bionic, wearable and rehabilitation robots, and can reduce system weight and cost, increase power-to-weight ratio and offer safer physical human-robot interaction. However, these actuators possess several disadvantages, for example fishing line based actuators possess low strength and are complex to drive, and SMA possesses a low percentage contraction and has high hysteresis. This paper presents a novel artificial actuator (known as an SMA-fishing-line) made of fishing line and SMA twisted then coiled together, which can be driven directly by an electrical voltage. Its output force can reach 2.65N at 7.4V drive voltage, and the percentage contraction at 4V driven voltage with a 3N load is 7.53%. An antagonistic bionic joint driven by the novel SMA-fishing-line actuators is presented, and based on an extended unparallel Prandtl-Ishlinskii (EUPI) model, its hysteresis behavior is established, and the error ratio of the EUPI model is determined to be 6.3%. A Joule heat model of the SMA-fishing-line is also presented, and the maximum error of the established model is 0.510mm. Based on this accurate hysteresis model, a composite PID controller consisting of PID and an integral inverse (I-I) compensator is proposed and its performance is compared with a traditional PID controller through simulations and experimentation. These results show that the composite PID controller possesses higher control precision than basic PID, and is feasible for implementation in an SMA-fishing-line driven antagonistic bionic joint

Design, synthesis, bioactivity and mechanism of action of novel myricetin derivatives containing amide and hydrazide

A series of myricetin derivatives containing amide and hydrazide were designed and synthesized. All the compounds were characterized by NMR and HRMS. Bioactivity test showed that some of the target compounds had excellent anti-tobacco mosaic virus (TMV) activity. In particular, the median effective concentration (EC50) values of the anti-TMV curative and protective activities of N-(2-(2-(2-((5,7-dimethoxy-4-oxo-2-(3,4,5-trimethoxyphenyl)-4H-chromen-3-yl)oxy)acetyl)hydrazineyl)-2-oxoethyl)-4-(trifluoromethyl)benzamide (G9) were 202.3 and 164.0 μg/mL respectively, superior to ningnanmycin (329.1, 230.3 μg/mL). Microscale thermophoresis (MST) and molecular docking showed that G9 had an excellent binding affinity with tobacco mosaic virus coat protein (TMV-CP) (Kd = 0.158 ± 0.024 μM), which was better than that of ningnanmycin (Kd = 2.074 ± 0.818 μM). Moreover, there were many interaction forces between G9 and the key amino acid residues of TMV-CP. The chlorophyll content and peroxidase (POD) activity of tobacco leaves treated with G9 increased significantly, indicating that G9 could improve the photosynthesis of tobacco leaves and stimulate the resistance of tobacco leaves to TMV. The insecticidal activity of G9 against Mythimna separata (M. separate) was found to be 95.2% at 200 μg/mL, which was close to bufenozide (100%). The insecticidal activity of myricetin was significantly improved after the introduction of active groups of amide and hydrazide, which could be further explored

Design, synthesis, and antiviral activities of myricetin derivatives containing phenoxypyridine

A series of myricetin derivatives containing phenoxypyridine structure were designed and synthesized on the basis of the natural product myricitrin, which were structurally characterized on NMR and HRMS. The results of antiviral activity tests showed that some of the target compounds exhibited better inhibitory effects. Among them, B19 and B21 showed better curative activity with EC50 values of 195.67 and 173.64 μg/mL, respectively, which were superior to that of the control agent ningnanmycin(NNM) (238.30 μg/mL). B21 showed better protective activity with EC50 value of 236.37 μg/mL, which was better than that of the control agent NNM (269.89 μg/mL). The results of microcalorimetry showed that B1, B19 and B21 had good binding affinity with tobacco mosaic virus capsid protein (TMV-CP), and the Kd values were 0.059, 0.093 and 0.069 μM, which was higher than that of NNM (Kd = 2.78 μM). The molecular docking results showed that the hydrogen bond lengths between B1, B21 and the key amino acid residues of TMV-CP were shorter and with more tightly bound than those of NNM. In B21-treated tobacco leaves, chlorophyll content and superoxide dismutase (SOD) activity were significantly elevated, indicating that B21 can participate in regulating plant photosynthesis as well as defense enzymes and inducing plants to improve disease resistance