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1,599 results on '"Xiang Meng"'

109. Anomalous segmental dynamics of supercooled polyrotaxane melts: A computer simulation study.

Author

Jia, Xiang-Meng and Zhou, Jiajia

Subjects
*COMPUTER simulation, *GLASS transition temperature, *MOLECULAR dynamics, *MELTING, *LINEAR dynamical systems
Abstract

Polyrotaxanes, which consist of mechanically interlocked bonds with rings threaded onto soft polymer chains, exhibit unique mechanical properties and find applications in diverse fields. In this study, we investigate the anomalous segmental dynamics of supercooled polyrotaxane melts using coarse-grained molecular dynamics simulations. Our simulations reveal that the presence of rings effectively reduces the packing efficiency, resulting in well-contained local motion even below the glass transition temperature. We also observe variations in dynamical free volume, characterized by the Debye–Waller factor, which shows a minimum at a ring coverage of 0.1 on threading chains. Such a non-monotonic dependence on coverage shows great consistency in structural relaxation time and dynamic heterogeneity. Specifically, the high segmental mobility of threading linear chains at large coverage can be attributed to the increased dynamical free volume due to supported rigid rings. However, such anomalous segmental dynamics is limited to length scales smaller than one ring size. Beyond this characteristic length scale, the diffusion is dominated by topological constraints, which significantly reduce the mobility of polyrotaxanes and enhance the dynamic heterogeneity. These findings offer microscopic insights into the unique packing structures and anomalous segmental dynamics of supercooled polyrotaxane melts, facilitating the design of advanced materials based on mechanical interlocking polymers for various applications. [ABSTRACT FROM AUTHOR]

Published
2023
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123. Single wavelength 480 Gb/s direct detection over 80km SSMF enabled by Stokes Vector Kramers Kronig transceiver

Author

Hoang, Thang, Sowailem, Mohammed, Zhuge, Qunbi, Xing, Zhenping, Morsy-Osman, Mohamed, El-Fiky, Eslam, Fan, Sujie, Xiang, Meng, and Plant, David V.

Subjects
Electrical Engineering and Systems Science - Signal Processing
Abstract

We propose 4D modulation with directed detection employing a novel Stokes-Vector Kramers-Kronig transceiver. It shows that employing Stokes vector receiver, transmitted digital carrier and Kramers-Kronig detection offers an effective way to de-rotate polarization multiplexed complex double side band signal without using a local oscillator at receiver. The impact of system parameters and configurations including carrier-to-signal-power ratio, guard band of the digital carrier, oversampling ratio and real MIMO is experimentally investigated. Finally, a record 480 Gb/s data rate over 80 km SSMF is achieved in a 60 Gbaud PDM-16QAM single carrier experiment with a BER below the threshold of 2.0x10-2

Published
2017
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139. Lithium-Rich Deposits in the Liangshan Formation during the Permian in the Upper Yangtze Plate, China.

Author

Gong, Yin, Liu, Chun-Yao, Liu, Yin, Lei, Li, Xiang, Meng, Yang, Bo, Zhou, Zhou, Zhang, Yang, Yang, Xiang-Rong, Yan, Lei, and Xiong, Yuan

Subjects
SEDIMENTATION & deposition, GEOCHEMISTRY, WEATHERING, MINERALOGY, LIMESTONE
Abstract

With the increasing demand for lithium (Li) resources in industry, there has been new attention on clay-type lithium-rich deposits recently. In this study, a Li-rich clay deposit with a Li2O content up to 0.3% in the Liangshan Formation in the upper Yangtze, South China Block was demonstrated. We analysed the mineralogy and element geochemistry of the samples from the Liangshan Formation and its underlying and overlying layers. Kaolinite (average 53%, up to 93%) was the major mineral in the samples from the Liangshan Formation. The Li concentrations increased with increasing kaolinite compositions and Al2O3 concentrations. Furthermore, based on the geochemical indicators, it was suggested that the clay formation and Li enrichment were related to the weathering processes of the bottom impure limestone under the hot and wet climate, and the sedimentary processes in the anoxic, still, and flat land–sea interaction area in the Upper Yangtze. The Li was probably sourced from the bottom impure limestone during the weathering stage. The samples from the Liangshan Formation also showed REE enrichment from 117 to 729 μg/g. [ABSTRACT FROM AUTHOR]

Published
2024
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