Pressure-induced electronic topological transition and superconductivity in topological insulator Bi2Te2.1Se0.9

Great attention has been drawn to topological superconductivity due to its potential application in topological quantum computing. Meanwhile, pressure is regarded as a powerful tool for tuning electronic structure and even inducing superconductivity in topological insulators. As a well-defined topological insulator, Bi2Te2.1Se0.9 can be a suitable candidate to search for topological superconductivity and study its intrinsic property. In this paper, we report the occurrence of superconductivity and electronic topological transition (ETT) in Bi2Te2.1Se0.9 with applied pressure. Superconductivity can be observed at 2.4 GPa with the Tconset around 6.6 K in Bi2Te2.1Se0.9 by resistance measurement, and the corresponding structure resolved by X-ray diffraction and Raman experiments doesn't change below the pressure of 8.4 GPa. Moreover, at about 3.0 GPa, the abnormal changes of c/a as well as the full width at half maximum (FWHM) of mode indicate the occurrence of electronic topological transition (ETT). These results indicate that superconductivity can be realized in doped topological insulator Bi2Te2.1Se0.9 in the low-pressure rhombohedral phase

Trajectory tracking for agricultural tractor based on improved fuzzy sliding mode control

Trajectory tracking is one of the key technologies for tractor automatic navigation. Its main purpose is to adjust the steering mechanism of the tractor to follow the planned trajectory. Thus, in this paper a trajectory tracking control system is designed for an agricultural tractor with the electric power steering mechanism. A DC brush motor is added on the steering column of the tractor and the hardware circuits for the steering controller are designed to control the front wheel angel. The three degrees of freedom model of the tractor is established, and a trajectory tracking control system is proposed including a fuzzy sliding mode controller and a steering angle tracking controller designed according to the internal mode control and minimized sensitivity theory. The effectiveness of the designed trajectory tracking control system is demonstrated by simulation analyses in reference to the planed trajectory

Trajectory tracking for agricultural tractor based on improved fuzzy sliding mode control.

Trajectory tracking is one of the key technologies for tractor automatic navigation. Its main purpose is to adjust the steering mechanism of the tractor to follow the planned trajectory. Thus, in this paper a trajectory tracking control system is designed for an agricultural tractor with the electric power steering mechanism. A DC brush motor is added on the steering column of the tractor and the hardware circuits for the steering controller are designed to control the front wheel angel. The three degrees of freedom model of the tractor is established, and a trajectory tracking control system is proposed including a fuzzy sliding mode controller and a steering angle tracking controller designed according to the internal mode control and minimized sensitivity theory. The effectiveness of the designed trajectory tracking control system is demonstrated by simulation analyses in reference to the planed trajectory

Numerical simulation and engineering application of comb-shaped directional long borehole hydraulic fracturing under different arrangement of holes

In order to avoid the blindness of the hydraulic fracturing of the directional long borehole in coal mine 2130 of Xinjiang Coking Coal Group, and to accurately grasp the extension and expansion of hydraulic fracturing under different hole layout methods, this paper uses the numerical simulation method to carry out hydraulic fracturing numerical simulation for comb directional long borehole in 4# coal seam of coal mine 2130 with a buried depth of 500 m. The simulation results show that the different hole layout methods have obvious effects on hydraulic fracturing initiation pressure, crack initiation position, fracture mode and crack extension and expansion law, combined with the actual situation of 4# coal seam in coal mine 2130, the optimal drilling hole layout method and fracturing parameters are optimized for engineering practice, and good fracturing results have been achieved. Compared with the previous hydraulic fracturing measures at this level, the drainage concentration is increased by 2.7 times, and the scalar amount of drainage increased by 11.8 times

Identifying the most critical behavioral lifestyles associated with MAFLD: evidence from the NHANES 2017–2020

Background & aimsAccumulating studies have demonstrated associations between single lifestyle exposures and metabolic dysfunction-associated fatty liver disease (MAFLD). However, the joint effects of lifestyle exposures remain unclear, hindering the development of targeted prevention and control strategies. We aimed to investigate the joint associations between lifestyle exposomes and MAFLD.MethodsThis study included 5,002 participants from NHANES 2017–2020. Lifestyle exposomes, including sleep duration, metabolic equivalent of task (MET), Healthy Eating Index (HEI)-2015 score, alcohol consumption, and smoke exposure, were identified from questionnaire data. MAFLD was diagnosed by vibration-controlled transient elastography measurements and laboratory data. A logistic regression model and the weighted quantile sum method were used to evaluate the associations of single and joint lifestyle exposomes, respectively, with MAFLD. The population attributable fractions (PAFs) were calculated to assess the population benefits of different intervention strategies.ResultsPer-quartile range increases in sleep duration (OR=0.883, 95% CI: 0.826–0.944), MET (0.916, 0.871–0.963), and HEI-2015 score (0.827, 0.756–0.904) were significantly associated with MAFLD. The joint exposure of sleep duration, MET, and HEI-2015 score was associated with MAFLD (0.772, 0.688–0.865), with the highest weight (importance) for MET (0.526). PAFs revealed greater intervention benefits for sleep and the HEI-2015 when the majority of the population (>5%) had a low MAFLD risk (weak intervention targets), whereas MET was the most efficient intervention strategy when minority populations (≤5%) had a low MAFLD risk (strong intervention targets).ConclusionThis study demonstrated significant associations between MAFLD and single and joint exposures to sleep duration, MET, and HEI-2015 and identified physical activity as the most important lifestyle factor. Further population benefit analyses may provide evidence and suggestions for population-level interventions

New Assembly of Acetamidinium Nitrate Modulated by High Pressure

High pressure is an essential thermodynamic parameter in exploring the performance of condensed energetic materials. Combination of high-pressure techniques and supramolecular chemistry opens a new avenue for synthesis of high energy density materials. Herein, we fabricate a new high-pressure-assisted assembly of energetic material acetamidinium nitrate (C₂N₂H₇⁺·NO₃^–, AN) with <i>P</i>-1 symmetry after a 0–12 GPa–0 treatment at room temperature, which exhibits a density that is 9.8% higher than that of the initial <i>P</i>2₁/<i>m</i> phase. Evolution of intermolecular lattice modes in Raman spectra and synchrotron X-ray diffraction (XRD) patterns provide strong evidence for this transition in the 1.3–3.4 GPa range. The mechanism involves relative motions between ionic pairs in the hydrogen-bonded array and distortions of building blocks

High-Pressure Study of Perovskite-Like Organometal Halide: Band-Gap Narrowing and Structural Evolution of [NH₃‑(CH₂)₄‑NH₃]CuCl₄

Searching for nontoxic and stable perovskite-like alternatives to lead-based halide perovskites for photovoltaic application is one urgent issue in photoelectricity science. Such exploration inevitably requires an effective method to accurately control both the crystalline and electronic structures. This work applies high pressure to narrow the band gap of perovskite-like organometal halide, [NH₃-(CH₂)₄-NH₃]­CuCl₄ (DABCuCl₄), through the crystalline-structure tuning. The band gap keeps decreasing below ∼12 GPa, involving the shrinkage and distortion of CuCl₄^2–. Inorganic distortion determines both band-gap narrowing and phase transition between 6.4 and 10.5 GPa, and organic chains function as the spring cushion, evidenced by the structural transition at ∼0.8 GPa. The supporting function of organic chains protects DABCuCl₄ from phase transition and amorphization, which also contributes to the sustaining band-gap narrowing. This work combines crystal structure and macroscopic property together and offers new strategies for the further design and synthesis of hybrid perovskite-like alternatives

Long-term exposure to ambient PM2.5 and its constituents is associated with MAFLD

Background &amp; Aims: Existing evidence suggests that long-term exposure to ambient fine particulate pollution (PM2.5) may increase metabolic dysfunction-associated fatty liver disease (MAFLD) risk. However, there is still limited evidence on the association of PM2.5 constituents with MAFLD. Therefore, this study explores the associations between the five main chemical constituents of PM2.5 and MAFLD to provide more explicit information on the liver exposome. Methods: A total of 76,727 participants derived from the China Multi-Ethnic Cohort, a large-scale epidemic survey in southwest China, were included in this study. Multiple linear regression models were used to estimate the pollutant-specific association with MAFLD. Weighted quantile sum regression was used to evaluate the joint effect of the pollutant-mixture on MAFLD and identify which constituents contribute most to it. Results: Three-year exposure to PM2.5 constituents was associated with a higher MAFLD risk and more severe liver fibrosis. Odds ratios for MAFLD were 1.480, 1.426, 1.294, 1.561, 1.618, and 1.368 per standard deviation increase in PM2.5, black carbon, organic matter, ammonium, sulfate, and nitrate, respectively. Joint exposure to the five major chemical constituents was also positively associated with MAFLD (odds ratio 1.490, 95% CI 1.360–1.632). Nitrate contributed most to the joint effect of the pollutant-mixture. Further stratified analyses indicate that males, current smokers, and individuals with a high-fat diet might be more susceptible to ambient PM2.5 exposure than others. Conclusions: Long-term exposure to PM2.5 and its five major chemical constituents may increase the risk of MAFLD. Nitrate might contribute most to MAFLD, which may provide new clues for liver health. Males, current smokers, and participants with high-fat diets were more susceptible to these associations. Impact and implications: This large-scale epidemiologic study explored the associations between constituents of fine particulate pollution (PM2.5) and metabolic dysfunction-associated fatty liver disease (MAFLD), and further revealed which constituents play a more important role in increasing the risk of MAFLD. In contrast to previous studies that examined the effects of PM2.5 as a whole substance, this study carefully explored the health effects of the individual constituents of PM2.5. These findings could (1) help researchers to identify the specific particles responsible for hepatotoxicity, and (2) indicate possible directions for policymakers to efficiently control ambient air pollution, such as targeting the sources of nitrate pollution