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In the era of the Internet of Things (IoT), the provision of sustainable power to distributed, mobile, and low-power-consumption electronic devices is a critical challenge. To overcome this challenge, the triboelectric nanogenerator (TENG), a highly efficient high-entropy mechanical energy harvesting device, was developed in 2012. This device enables the direct conversion of irregular and low-frequency mechanical energy into pulsed alternating current (AC) signals. However, the incompatibility of most electronic devices with AC signals necessitates rectifier circuits or generators that deliver direct current (DC) signals. In recent years, DC-TENGs have undergone extensive development, achieving significant milestones in various application fields while also facing crucial challenges that require solutions. In this review, three categories of DC-TENG devices with distinct operating mechanisms are comprehensively explored: multiphase coupling, mechanical rectification, and air breakdown. Their typical structures and working mechanisms are thoroughly discussed, and specific output performance limitations, along with corresponding optimization strategies, are identified. Furthermore, the applications of DC-TENGs in various scenarios are summarized. Finally, the challenges faced by DC-TENGs and potential solutions are analyzed to guide further advancements in this technology. [ABSTRACT FROM AUTHOR]

Dietary habits are essential in the mean age at menarche (AAM). However, the causal relationship between these factors remains unclear. Therefore, this study aimed to elucidate the genetic relationship between dietary habits and AAM. Genetic summary statistics for dietary habits were obtained from the UK Biobank. GWAS summary data for AAM was obtained from the ReproGen Consortium. Linkage disequilibrium score regression was used to test genetic correlations between dietary habits and AAM. The Mendelian randomization (MR) analyses used the inverse-variance weighted method. Genetic correlations with AAM were identified for 29 candi-date dietary habits, such as milk type (skimmed, semi-skimmed, full cream; coefficient = 0.2704, Pldsc = 1.13 × 10−14). MR evaluations revealed that 19 dietary habits were associated with AAM, including bread type (white vs. any other; OR 1.71, 95% CI 1.28–2.29, Pmr = 3.20 × 10−4), tablespoons of cooked vegetables (OR 0.437, 95% CI 0.29–0.67; Pmr = 1.30 × 10−4), and cups of coffee per day (OR 0.72, 95% CI 0.57–0.92, Pmr = 8.31 × 10−3). These results were observed to be stable under the sensitivity analysis. Our study provides potential insights into the genetic mechanisms underlying AAM and evidence that dietary habits are associated with AAM. [ABSTRACT FROM AUTHOR]

The stunning tails of comets are interesting astronomical phenomena to human beings and have been noticed for thousands of years. The bright tails also emit substantial materials into interplanetary space, including dusts and charged particles. The charged particles are picked up by solar wind magnetic fields, and thus could propagate together with solar wind to influence planetary space environments. Simultaneous measurements of comet materials, planetary space, and ground environments are crucial for understanding cometary impacts to planets, while such observations are quite rare. In this article, we present a full chain from the comet tail, to the solar wind cometary particles, and the impacts on the ground. Intense auroral events are observed when the cometary materials are observed in the Earthʼs upstream solar wind. Our results provide direct evidence that cometary ions could contribute substantial dynamic pressure in driving geomagnetic activities and the associated auroral intensifications. [ABSTRACT FROM AUTHOR]

Foreshock cavitons are transient phenomena observed in the terrestrial foreshock region. They are characterized by a simultaneous depression of magnetic field magnitude and plasma density, which are bounded with enhancements of these two parameters and surrounded by ultralow frequency (ULF) waves. Previous studies focused on the interplanetary magnetic field (IMF) conditions, solar wind (SW) conditions, and the growth of the foreshock waves related to the generation of foreshock cavitons. Previously, a multipoint spacecraft analysis method using Cluster data was applied to analyze only two foreshock cavitons, and this method did not consider uncertainties. In this study, multipoint spacecraft analysis methods, including the timing method, the minimum directional derivative (MDD) method, and the spatiotemporal difference (STD) method are applied to determine the velocity in both spacecraft and solar wind frames. The propagation properties show good agreement with previous results from simulations and observations that most cavitons move sunward in the solar wind frame, with the velocities larger than the Alfvén speed. The propagation properties of foreshock cavitons support the formation mechanism of cavitons in previous simulations, which suggested that cavitons are formed due to the nonlinear evolution of compressive ULF waves. We find that there is clear decreasing trend between the size of cavitons and their velocity in the solar wind frame. In addition, the timing method considering errors has been applied to study the evolution properties by comparing the velocities with errors of the leading and trailing edges, and we identify three stable cavitons and one contracting caviton, which has not been studied before. Most cavitons should remain stable when they travel toward the Earth's bow shock. The relationship between the size of foreshock cavitons and their distance from the bow shock is also discussed. [ABSTRACT FROM AUTHOR]