In this study, to further improve the dynamic performance and steady-state accuracy of the electromagnetic linear actuator (EMLA) for the direct-drive system, the adaptive non-singular terminal sliding mode controller (ANTSMC) based on an improved disturbance observer (IDOB) is proposed. Accurate modeling of the EMLA based on the LuGre friction model was obtained by identification. Aiming at the continuous disturbance of the system, a non-singular terminal sliding mode control based on improved exponential reaching law (IERL) is designed, which is combined with the advantages of fuzzy control. Adaptive adjustment of the IERL gain is achieved to ensure finite time convergence of the tracking error while suppressing system jitter. Based on the IDOB to achieve effective observation compensation under noise disturbance and further improve the system robustness. The stability of the control is analyzed based on the Lyapunov function. The results show that the proposed method suppresses the jitter and improves the tracking performance and robustness of the servo system for different desired trajectories effectively.

Timosaponin BII is one of the most abundant Anemarrhena saponins and is in a phase II clinical trial for the treatment of dementia. However, the pharmacological activity of timosaponin BII does not match its low bioavailability. In this study, we aimed to determine the effects of gut microbiota on timosaponin BII metabolism. We found that intestinal flora had a strong metabolic effect on timosaponin BII by HPLC-MS/MS. At the same time, seven potential metabolites (M1-M7) produced by rat intestinal flora were identified using HPLC/MS-Q-TOF. Among them, three structures identified are reported in gut microbiota for the first time. A comparison of rat liver homogenate and a rat liver microsome incubation system revealed that the metabolic behavior of timosaponin BII was unique to the gut microbiota system. Finally, a quantitative method for the three representative metabolites was established by HPLC-MS/MS, and the temporal relationship among the metabolites was initially clarified. In summary, it is suggested that the metabolic characteristics of gut microbiota may be an important indicator of the pharmacological activity of timosaponin BII, which can be applied to guide its application and clinical use in the future.

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Cap carbonate of the early Ediacaran period represents an abrupt climate shift from severe Marinoan glaciation to a post-glacial warm environment. Some consensuses on the distinctive negative excursion of δ 13 Ccarb and the origin of its unique sedimentary structures have been reached over the past decades, but certain aspects such as the distribution and redox conditions of cap carbonate still remain controversial. To resolve these issues, we collected detailed samples of the Doushantuo cap carbonate from the Ganlong-Fanyang section and the Poutoushang reservoir section in the Danzhai County, southeast Guizhou Province, respectively. We conducted carbon and oxygen isotope analysis and trace element analysis in this study. The Ganlong-Fanyang section was possibly situated in a submarine highland because of its higher carbon isotope than that of the Potoushang section according to the carbon isotopic gradient. Negative carbon isotope excursions at the basal Doushantuo cap carbonate from the two sections correlate well with those from other equivalent cap carbonates and were corresponding to the first one (SN1 or EN1) of the carbon isotopic curve during the Ediacaran period, implying a remarkable global event after the post-Marinoan glaciation. Geochemical features of trace elements and rare earth elements support an overall oxygenrich condition with syn-depositional or pene-contemporaneous hydrothermal activities and methane seeps during the deposition of cap carbonate. We reconstruct a new sedimentary model that the Doushantuo cap carbonates were mainly precipitated in relatively shallow-to deep-water shelf environments without disturbance by abundant terrestrial materials, which may be on isolated platforms over the early developed grabens in a deep-water basinal condition, rather than within the entire oceanic basin.