228 research outputs found

    Human Development from the Perspective of Ecology

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    The pursuit of the liberation of all mankind and the comprehensive development of human freedom is the theme of all marxist theories.Marx in the criticism of classical political economics "abstract", to the whole history of the definition of "general", found the abstract "general" of the people behind the objective existence and state of development, so as to clearly indicate the relationship between man and nature of human development has experienced on the basis of the nature of the dependence on one stage, gradually from natural objects depends on the stage and with the natural fusion of freedom comprehensive stage, and the concrete connotation of man's free overall and implementation path

    A Crosslinked Polyethyleneglycol Solid Electrolyte Dissolving Lithium Bis(trifluoromethylsulfonyl)imide for Rechargeable Lithium Batteries

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    Replacing liquid electrolytes with solid ones can provide advantages in safety, and all-solid-state batteries with solid electrolytes are proposed to solve the issue of the formation of lithium dendrites. In this study, a crosslinked polymer composite solid electrolyte was presented, which enabled the construction of lithium batteries with outstanding electrochemical behavior over long-term cycling. The crosslinked polymeric host was synthesized through polymerization of the terminal amines of O,O-bis(2-aminopropyl) polypropylene glycol-blockpolyethylene glycol-block-polypropylene glycol and terminal epoxy groups of bisphenol A diglycidyl ether at 90Ā°C and provided an amorphous matrix for Liāŗ dissolution. This composite solid electrolyte containing Liāŗ salt and garnet filler exhibited high flexibility, which supported the formation of favorable interfaces with the active materials, and possessed enough mechanical strength to suppress the penetration of lithium dendrites. Ionic conductivities higher than 5.0x10ā»ā“ Scmā»Ā¹ above 45Ā°C were obtained as well as a wide electrochemical stability window (>4.51 V vs. Li/Liāŗ) and a high Liāŗ diffusion coefficient (ā‰ˆ16.6x10ā»Ā¹Ā³mĀ² sĀÆĀ¹). High cycling stability (>500 cycles or 1000 h) was demonstrated

    Study of the Lithium Storage Mechanism of N-Doped Carbon-Modified Cuā‚‚S Electrodes for Lithium-Ion Batteries

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    Owing to their high specific capacity and abundant reserve, Cux_{x}S compounds are promising electrode materials for lithium-ion batteries (LIBs). Carbon compositing could stabilize the Cux_{x}S structure and repress capacity fading during the electrochemical cycling, but the corresponding Li+^{+} storage mechanism and stabilization effect should be further clarified. In this study, nanoscale Cu2_{2}S was synthesized by CuS co-precipitation and thermal reduction with polyelectrolytes. High-temperature synchrotron radiation diffraction was used to monitor the thermal reduction process. During the first cycle, the conversion mechanism upon lithium storage in the Cu2_{2}S/carbon was elucidated by operando synchrotron radiation diffraction and in situ X-ray absorption spectroscopy. The N-doped carbon-composited Cu2_{2}S (Cu2_{2}S/C) exhibits an initial discharge capacity of 425 mAhā€‰gāˆ’1^{-1} at 0.1 Aā€‰gāˆ’1^{-1}, with a higher, long-term capacity of 523 mAhā€‰gāˆ’1^{-1} at 0.1 Aā€‰gāˆ’1^{-1} after 200 cycles; in contrast, the bare CuS electrode exhibits 123 mAhā€‰gāˆ’1^{-1} after 200 cycles. Multiple-scan cyclic voltammetry proves that extra Li+ storage can mainly be ascribed to the contribution of the capacitive storage

    Phototriggered Complex Motion by Programmable Construction of Light-Driven Molecular Motors in Liquid Crystal Networks

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    Recent developments in artificial molecular machines have enabled precisely controlled molecular motion, which allows several distinct mechanical operations at the nanoscale. However, harnessing and amplifying molecular motion along multiple length scales to induce macroscopic motion are still major challenges and comprise an important next step toward future actuators and soft robotics. The key to addressing this challenge relies on effective integration of synthetic molecular machines in a hierarchically aligned structure so numerous individual molecular motions can be collected in a cooperative way and amplified to higher length scales and eventually lead to macroscopic motion. Here, we report the complex motion of liquid crystal networks embedded with molecular motors triggered by single-wavelength illumination. By design, both racemic and enantiomerically pure molecular motors are programmably integrated into liquid crystal networks with a defined orientation. The motors have multiple functions acting as cross-linkers, actuators, and chiral dopants inside the network. The collective rotary motion of motors resulted in multiple types of motion of the polymeric film, including bending, wavy motion, fast unidirectional movement on surfaces, and synchronized helical motion with different handedness, paving the way for the future design of responsive materials with enhanced complex functions

    Understanding the Li-ion storage mechanism in a carbon composited zinc sulfide electrode

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    Sulfide compounds are interesting conversion electrode materials for Li-ion batteries, due to their high theoretical capacity. However, they suffer from large volumetric changes and fast capacity fading. To overcome these issues, nanosized zinc sulfide (ZnS) modified with polyelectrolytes and graphene (ZnS-C/G) has been synthesized and investigated as an enhanced conversion-alloying anode material. In situ synchrotron X-ray diffraction and X-ray absorption spectroscopy are used to elucidate the Li storage process during the 1st cycle. In addition, the evolution of internal resistance and the corresponding solid electrolyte interphase (SEI) formation during the 1st cycle are discussed based on electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The results reveal that the formation of lithiated products and the SEI layer at different voltages can influence Li+ diffusion into the electrode. Moreover, an artificial carbon layer can not only facilitate Li+ transport but also avoid the direct formation of the SEI layer on the surface of active particles. Compared to bare ZnS, the ZnS-C/G electrode shows outstanding rate capability and cycling capacity (571 mA h gāˆ’1 after 120 cycles at a specific current of 1.0 A gāˆ’1 with a retention rate of 94.4%). The high capacity at elevated current density is ascribed to the contribution of capacitive charge storage

    Longer screen time utilization is associated with the polygenic risk for Attention-deficit/hyperactivity disorder with mediation by brain white matter microstructure

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    Attention-deficit/hyperactivity disorder (ADHD) has been reported to be associated with longer screen time utilization (STU) at the behavioral level. However, whether there are shared neural links between ADHD symptoms and prolonged STU is not clear and has not been explored in a single large-scale dataset. Leveraging the genetics, neuroimaging and behavioral data of 11,000+ children aged 9-11 from the Adolescent Brain Cognitive Development cohort, this study investigates the associations between the polygenic risk and trait for ADHD, STU, and white matter microstructure through cross-sectionally and longitudinal analyses. Children with higher polygenic risk scores for ADHD tend to have longer STU and more severe ADHD symptoms. Fractional anisotropy (FA) values in several white matter tracts are negatively correlated with both the ADHD polygenic risk score and STU, including the inferior frontal-striatal tract, inferior frontal-occipital fasciculus, superior longitudinal fasciculus and corpus callosum. Most of these tracts are linked to visual-related functions. Longitudinal analyses indicate a directional effect of white matter microstructure on the ADHD scale, and a bi-directional effect between the ADHD scale and STU. Furthermore, reduction of FA in several white matter tracts mediates the association between the ADHD polygenic risk score and STU. These findings shed new light on the shared neural overlaps between ADHD symptoms and prolonged STU, and provide evidence that the polygenic risk for ADHD is related, via white matter microstructure and the ADHD trait, to STU. This study was mainly supported by NSFC and National Key R&D Program of China. [Abstract copyright: Copyright Ā© 2022 The Author(s). Published by Elsevier B.V. All rights reserved.
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