Role of disorder in half-filled high Landau levels

We study the effects of disorder on the quantum Hall stripe phases in half-filled high Landau levels using exact numerical diagonalization. We show that, in the presence of weak disorder, a compressible, striped charge density wave, becomes the true ground state. The projected electron density profile resembles that of a smectic liquid. With increasing disorder strength W, we find that there exists a critical value, W_c \sim 0.12 e^2/\epsilon l, where a transition/crossover to an isotropic phase with strong local electron density fluctuations takes place. The many-body density of states are qualitatively distinguishable in these two phases and help elucidate the nature of the transition.Comment: 4 pages, 4 figure

3D Nondestructive Visualization and Evaluation of TRISO Particles Distribution in HTGR Fuel Pebbles Using Cone-Beam Computed Tomography

A nonuniform distribution of tristructural isotropic (TRISO) particles within a high-temperature gas-cooled reactor (HTGR) pebble may lead to excessive thermal gradients and nonuniform thermal expansion during operation. If the particles are closely clustered, local hotspots may form, leading to excessive stresses on particle layers and an increased probability of particle failure. Although X-ray digital radiography (DR) is currently used to evaluate the TRISO distributions in pebbles, X-ray DR projection images are two-dimensional in nature, which would potentially miss some details for 3D evaluation. This paper proposes a method of 3D visualization and evaluation of the TRISO distribution in HTGR pebbles using cone-beam computed tomography (CBCT): first, a pebble is scanned on our high-resolution CBCT, and 2D cross-sectional images are reconstructed; secondly, all cross-sectional images are restructured to form the 3D model of the pebble; then, volume rendering is applied to segment and display the TRISO particles in 3D for visualization and distribution evaluation. For method validation, several pebbles were scanned and the 3D distributions of the TRISO particles within the pebbles were produced. Experiment results show that the proposed method provides more 3D than DR, which will facilitate pebble fabrication research and production quality control

Effects of epigallocatechin-3-gallate on bovine oocytes matured

Objective Epigallocatechin-3-gallate (EGCG) is a major ingredient of catechin polyphenols and is considered one of the most promising bioactive compounds in green tea because of its strong antioxidant properties. However, the protective role of EGCG in bovine oocyte in vitro maturation (IVM) has not been investigated. Therefore, we aimed to study the effects of EGCG on IVM of bovine oocytes. Methods Bovine oocytes were treated with different concentrations of EGCG (0, 25, 50, 100, and 200 μM), and the nuclear and cytoplasmic maturation, cumulus cell expansion, intracellular reactive oxygen species (ROS) levels, total antioxidant capacity, the early apoptosis and the developmental competence of in vitro fertilized embryos were measured. The mRNA abundances of antioxidant genes (nuclear factor erythriod-2 related factor 2 [NRF2], superoxide dismutase 1 [SOD1], catalase [CAT], and glutathione peroxidase 4 [GPX4]) in matured bovine oocytes were also quantified. Results Nuclear maturation which is characterized by first polar body extrusion, and cytoplasmic maturation characterized by peripheral and cortical distribution of cortical granules and homogeneous mitochondrial distribution were significantly improved in the 50 μM EGCG-treated group compared with the control group. Adding 50 μM EGCG to the maturation medium significantly increased the cumulus cell expansion index and upregulated the mRNA levels of cumulus cell expansion-related genes (hyaluronan synthase 2, tumor necrosis factor alpha induced protein 6, pentraxin 3, and prostaglandin 2). Both the intracellular ROS level and the early apoptotic rate of matured oocytes were significantly decreased in the 50 μM EGCG group, and the total antioxidant ability was markedly enhanced. Additionally, both the cleavage and blastocyst rates were significantly higher in the 50 μM EGCG-treated oocytes after in vitro fertilization than in the control oocytes. The mRNA abundance of NRF2, SOD1, CAT, and GPX4 were significantly increased in the 50 μM EGCG-treated oocytes. Conclusion In conclusion, 50 μM EGCG can improve the bovine oocyte maturation, and the protective role of EGCG may be correlated with its antioxidative property

Research on the control strategy of phase balance in H-bridge cascade SVG

Based on the H-bridge cascaded SVG as one of the best solutions to effectively compensate reactive currents, this article focuses on the cascaded high-voltage H-bridge SVG phase balance problem. While analyzing the influence factors of the SVG DC side voltage, it summarizes and introduces 5 SVG phase balance control strategy ， Analyzed its real-time performance, stability, applicable occasions, algorithm and hardware circuit complexity, etc.Some control strategies have been simulated and verified, and the simulation results have reached the expected value, which provides a reference for the selection of balance control strategies for high-voltage SVG equipment

Amphiphilic Bowl-Shaped Janus Particles Prepared via Thiol–Ene Click Reaction for Effective Oil–Water Separation

Janus particles for oil–water separation have attracted widespread attention in recent years. Herein, we prepared a bowl-shaped Janus particle that could rapidly separate oil and water through a thiol–ene click reaction and selective etching. Firstly, snowman-like composite microspheres based on silica and mercaptopropyl polysilsesquioxane (SiO2@MPSQ) were prepared by a hydrolytic condensation reaction and phase separation, and the effects of the rotational speed and molar ratios on their microscopic morphologies were investigated. Subsequently, bowl-shaped Janus particles with convex hydrophilic and concave oleophilic surfaces were prepared via a thiol–ene click reaction followed by HF etching. Our amphiphilic bowl-shaped Janus particles could remarkably separate micro-sized oil droplets from an n-heptane–water emulsion with a separation efficiency of >98% within 300 s. Based on the experimental and theoretical results, we proposed the underlying mechanism for the coalescence of oil droplets upon the addition of the amphiphilic bowl-shaped Janus particles

Varying Responses of Vegetation Greenness to the Diurnal Warming across the Global

The distribution of global warming has been varying both diurnally and seasonally. Little is known about the spatiotemporal variations in the relationships between vegetation greenness and day- and night-time warming during the last decades. We investigated the global inter- and intra-annual responses of vegetation greenness to the diurnal asymmetric warming during the period of 1982–2015, using the normalized different vegetation index (NDVI, a robust proxy for vegetation greenness) obtained from the NOAA/AVHRR NDVI GIMMS3g dataset and the monthly average daily maximum (Tmax) and minimum temperature (Tmin) obtained from the gridded Climate Research Unit, University of East Anglia. Several findings were obtained: (1) The strength of the relationship between vegetation greenness and the diurnal temperature varied on inter-annual and seasonal timescales, indicating generally weakening warming effects on the vegetation activity across the global. (2) The decline in vegetation response to Tmax occurred mainly in the mid-latitudes of the world and in the high latitudes of the northern hemisphere, whereas the decline in the vegetation response to Tmin primarily concentrated in low latitudes. The percentage of areas with a significantly negative trend in the partial correlation coefficient between vegetation greenness and diurnal temperature was greater than that of the areas showing the significant positive trend. (3) The trends in the correlation between vegetation greenness and diurnal warming showed a complex spatial pattern: the majority of the study areas had undergone a significant declining strength in the vegetation greenness response to Tmax in all seasons and to Tmin in seasons except autumn. These findings are expected to have important implications for studying the diurnal asymmetry warming and its effect on the terrestrial ecosystem

Geographical Detector-Based Identification of the Impact of Major Determinants on Aeolian Desertification Risk.

Arid and semi-arid areas in North China are facing the challenge of a rising aeolian desertification risk (ADR) due to the intertwined effects of complex natural processes and intensified anthropogenic activities. An accurate quantitative assessment of the relationship between ADR and its determinants is beneficial for understanding the driving mechanisms of aeolian desertification and for controlling future desertification. Previous studies have failed to quantify the relative role of determinants driving ADR and have been limited in assessing their interactive impacts. In this study, a spatial variance analysis-based geographical detector methodology is used to quantify the effects of geological, physical, and human factors on the occurrence of ADR in an area characterized by mountains and hills in northern China. It is found that soil type, precipitation, and wind velocity are the major determinants of ADR, which implies that geological and physical elements (e.g., soil attribute) and climatic factors (e.g., precipitation and wind velocity) rather than human activities have played a greater role in the incidence of ADR. Particularly, the results show that the interaction of various determinants causes significant non-linearly enhanced impacts on the ADR. The findings of our study will assist local inhabitants and policy makers in developing measures for wind prevention and sand control to mitigate the effects of desertification in the region

Assessing the coupling coordination dynamics between land use intensity and ecosystem services in Shanxi's coalfields, China

The land use and cover changes (LUCC) caused by strong coal-mining activities and ecological restoration practices have seriously interfered with the ecosystem services (ESs) in the mining area. However, little attention has been paid to how to explore and improve the coordinated relationship between LUCC and ESs in mining areas. This study investigated the crucial relationship between ESs and land use intensity (LUI) in coal-mining areas, emphasizing the significance of understanding this interdependence for balanced human–land system development. Employing a coupling coordination degree (CCD) model, this research examined the evolving relationship across various reclamation stages of coalfields in Shanxi, China, spanning from 1986 to 2020. Additionally, stepwise and geographically weighted regressions were utilized to investigate the primary factors influencing CCD and their respective impacts. Notably, the comprehensive ecosystem service index (CESI) exhibited an upward trend between 1986 and 2020, whereas the LUI initially increased and subsequently declined during the reclamation stages. Moreover, the CCD between the LUI and CESI gradually evolved from mildly maladjusted to reluctant coordination throughout the various reclamation stages, gradually improved over time. Geographically, the region exhibited a coordinated level gradually expanded. Precipitation, slope, coal mining intensity, and industrial output emerged as primary CCD influencers. Coal mining intensity exerted negative impacts, whereas the impact of industrial output was minimal. Based on our findings, we recommend the timely and judicious reclamation of coalfields, taking into consideration the land's bearing capacity