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Dielectric capacitors are widely used in aerospace, power systems, and other fields. Working environments with ever‐increasing temperatures pose a new challenge to energy storage performance. Polyetherimide (PEI) has gained extensive research for its good high‐temperature properties. In order to further improve its energy storage performance at high temperatures, many researchers have worked on PEI all‐organic composites doping with molecular semiconductors. Previous studies generally only considered the effect of introduced deep traps on macroscopic properties such as electrical conductivity, electrical breakdown, and energy storage performance. It has been shown that only qualitative analyses can be performed from the perspective of charge trapping, and it is difficult to obtain quantitative results. Therefore, this work proposes to study the macroscopic properties of polymer dielectrics by combining charge trapping with molecular displacement. A comprehensive conduction‐breakdown‐energy storage model was established to explain the influence mechanism of molecular semiconductors on the improved energy storage performance of PEI composites at high temperatures. The molecular semiconductor fillers increase the coefficient of friction between molecular chains, which restricts the movement of molecular chains and also limits charge hopping. Therefore, the dielectrics have higher breakdown strengths and smaller conduction losses, which synergistically enhance the energy storage performance. [ABSTRACT FROM AUTHOR]

Rapid city expansion and intensive human activities have remarkably affected nitrogen flow, leading to increasingly intricate spatial heterogeneity of nitrogen flow. Focused on the temporal characteristics of nitrogen flow at certain city scales, the existing research has missed comprehensive grid-scale spatial models for nitrogen flow. To address this gap, this study develops a comprehensive spatial model for nitrogen flow by incorporating both natural and anthropic processes. Taking Xiamen as its research case, this study utilizes grid technology and spatial analysis to build a detailed spatial model for nitrogen flow at the grid scale. The results of spatial characteristics of Xiamen in 2015 revealed that hotspots of nitrogen input were primarily located in the surrounding areas outside and east of Xiamen, with the maximum nitrogen input reaching 20.07 × 104 kg/ha. However, the hotspots of nitrogen load in the atmosphere were concentrated in the urban center (i.e., Xiamen Island) and the nearby sea areas. The maximum nitrogen outputs can reach 18.32 × 104 kg/ha, which is 18 times the total nitrogen output to the water environment. Additionally, it was found that a significant gradient correlation exists between nitrogen flow and population density. These findings provide support for low-nitrogen spatial planning and emission reduction policymaking. [ABSTRACT FROM AUTHOR]

The molecular representation model is a neural network that converts molecular representations (SMILES, Graph) into feature vectors, and is an essential module applied across a wide range of artificial intelligence‐driven drug discovery scenarios. However, current molecular representation models rarely consider the three‐dimensional conformational space of molecules, losing sight of the dynamic nature of small molecules as well as the essence of molecular conformational space that covers the heterogeneity of molecule properties, such as the multi‐target mechanism of action, recognition of different biomolecules, dynamics in cytoplasm and membrane. In this study, a new model named GeminiMol is proposed to incorporate conformational space profiles into molecular representation learning, which extracts the feature of capturing the complicated interplay between the molecular structure and the conformational space. Although GeminiMol is pre‐trained on a relatively small‐scale molecular dataset (39290 molecules), it shows balanced and superior performance not only on 67 molecular properties predictions but also on 73 cellular activity predictions and 171 zero‐shot tasks (including virtual screening and target identification). By capturing the molecular conformational space profile, the strategy paves the way for rapid exploration of chemical space and facilitates changing paradigms for drug design. [ABSTRACT FROM AUTHOR]

High voltage direct-current (HVDC) cable is key equipment for utilizing offshore wind power. The high-temperature mechanical and DC electrical properties are two key figures for crosslinked polyethylene cable insulation, which are always contradictory and difficult to satisfy synchronously. To address the problem, we proposed crosslinked polyolefin (XLPO) insulation with 20.3% enhanced high-temperature mechanical stability and improved DC breakdown strength and volume resistivity. The thermally stimulated current results of XLPO showed depolarization current peaks at higher temperatures, responding to better inhibition of space charge and improved DC insulation. In addition, the XLPO exhibited thermodynamic compatibility with only one endothermic peak in differential scanning calorimetry thermograms and decreased small-angle X-ray scattering long-period. The strategy proposed in this work to enhance the comprehensive performance of cable insulation provides a promising route to next-generation HVDC cables. [ABSTRACT FROM AUTHOR]

Rapid urbanization inevitably exerts pressure on the surrounding ecological environment, and balancing the relationship between the ecological environment and urbanization is crucial for sustainable urban development. Taking the Yangtze River Delta urban agglomeration (YRDUA) as a case study, this paper utilizes MODIS data and nighttime light data to construct the MODIS Remote Sensing Ecological Index (MRSEI) and Comprehensive Nighttime Light Index (CNLI) distributions to depict ecological environment quality and urbanization levels. Based on this, the Coupled Coordination Degree (CCD) model is employed to calculate the coupling coordination level between the two, and the Geodetector is used to analyze the underlying causes affecting the CCD. The results indicate the following: (1) the overall ecological environment of the YRDUA tends to be stable, but there are significant differences between regions. Areas with deteriorating ecological conditions are concentrated in cities with higher rates of urbanization changes. (2) All cities are developing towards coordination, but there are imbalances in development among different regions. (3) The key factors affecting the CCD are derived from socioeconomic elements rather than natural elements, with the interaction between GDP and DEM having the strongest explanatory power for the CCD. (4) The CNLI is positively correlated with the CCD, the MRSEI is negatively correlated with the CCD, and the level of urbanization is the decisive factor for CCD changes. The research findings can provide theoretical guidance for promoting sustainable urban development. [ABSTRACT FROM AUTHOR]

The cross-section, thickness, and material of the autobody structure determine the crashworthiness and lightweight level. Different from the variables in traditional autobody design that are considered separately, the basic theory of 3G-optimization is to simultaneously consider geometric shape (Geometry), the thickness of structure (Gauge), and material grade (Grade) in structural optimization design, which is conducive to maximizing the lightweight potential of the structure. This paper presents a cross-section optimization method for multi-cell thin-walled structures based on 3G-optimization, which is used in the structural design of crash box. Based on full width frontal collision condition, the cross-section shape, thickness, and material variables of the multi-cell crash box are optimized simultaneously. Multiple sets of optimization schemes show obvious weight reduction effect while ensuring safety. Besides, the sub-system decoupling method and hybrid cellular automaton (HCA) method are applied to 3G-optimization process, which is beneficial to improve the calculation efficiency and provide a theoretical basis for the definition of the initial design space for 3G-optimization. [ABSTRACT FROM AUTHOR]