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Universal origin of glassy relaxation as recognized by configuration pattern matching

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National Science Review 2024年第5期11卷 343-351页

作者： hai-Bin Yu Liang gao Jia-Qi gao Konrad Samwer Wuhan National High Magnetic Field Center and School of Physics Huazhong University of Science and Technology I.Physikalisches Institut Universit?t G?ttingen

Relaxation processes are crucial for understanding the structural rearrangements of liquids and amorphous materials. However, the overarching principle that governs these processes across vastly different materials remains an open question. Substantial analysis has been carried out based on the motions of individual particles. Here, as an alternative, we propose viewing the global configuration as a single entity. We introduce a global order parameter, namely the inherent structure minimal displacement(IS Dmin), to quantify the variability of configurations by a pattern-matching technique. Through atomic simulations of seven model glass-forming liquids, we unify the influences of temperature, pressure and perturbation time on the relaxation dissipation, via a scaling law between the mechanical damping factor and IS Dmin. fundamentally,this scaling reflects the curvature of the local potential energy landscape. Our findings uncover a universal origin of glassy relaxation and offer an alternative approach to studying disordered systems.

关键词： glass transition metallic glass relaxation dynamics mechanical spectroscopy internal friction

A Study on the Impact of Chemical Structure on the Evolution of Aggregate Structure in Fiber-shaped High Density Polyethylene Vitrimer

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Chinese Journal of Polymer Science 2024年第10期42卷 1557-1565,I0013页

作者： Bing Wang Yuan-Chu gao hai Wang Hui Niu State Key Laboratory of Fine Chemicals School of Chemical EngineeringDalian University of TechnologyDalian116024China

Vitrimers have emerged as a prominent research area in the field of polymer *** of the studies have focused on synthesizing polymers with versatile dynamic crosslinking structures,while the impact of chemical structure on aggregate structure of vitrimers,particularly during polymer processing,remains insufficiently *** present study employed commercial maleic anhydride-grafted-high density polyethylene(M-g-HDPE)as the matrix and hexanediol as the crosslinker to facilely obtain fiber-shaped HDPE vitrimers through a reaction extrusion and post-drawing *** chemical structure characterization,morphology observation,thermal and mechanical properties investigation,as well as aggregate structure analysis,this work revealed the influence of dynamic bonds on the formation of aggregate structures during fiber-shaped vitrimers processing.A small amount of dynamic bonds in HDPE restricts the motion of PE chain during melt-extruding and post-drawing,resulting in a lower orientation of the PE ***,lamellar growth and fibril formation during post-drawing at high temperature are enhanced to some extent due to the competition between dynamic bond and chain *** uneven morphology of fibershaped HDPE vitrimers can be attributed to the stronger elastic effect brought by dynamic bonding,which plays a more dominant role in determining the mechanical properties of fiber-shaped vitrimers compared to aggregate *** Vitrimers have emerged as a prominent research area in the field of polymer *** of the studies have focused on synthesizing polymers with versatile dynamic crosslinking structures,while the impact of chemical structure on aggregate structure of vitrimers,particularly during polymer processing,remains insufficiently *** present study employed commercial maleic anhydride-grafted-high density polyethylene(M-g-HDPE)as the matrix and hexanediol as the crosslinker to facilely obtain fiber-shap

关键词： High density polyethylene vitrimer Fiber-shaped Aggregate structures Transesterification reaction

Risk Assessment of Deep-Water Horizontal X-Tree Installation

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China Ocean Engineering 2024年第2期38卷 210-220页

作者： MENG Wen-bo fu Guang-ming HUANG Yi LIU Shu-jie HUANG Liang gaoYong-hai CNOOC China Limited Zhanjiang BranchZhanjiang 524057China Key Laboratory of Unconventional Oil and Gas Development Ministry of Education(China University of Petroleum(East China))Qingdao 266580China

Due to the high potential risk and many influencing factors of subsea horizontal X-tree installation,to guarantee the successful completion of sea trials of domestic subsea horizontal X-trees,this paper established a modular risk evaluation model based on a fuzzy fault ***,through the analysis of the main process oftree down and combining the Offshore&Onshore Reliability Data(OREDA)failure statistics and the operation procedure and the data provided by the job,the fault tree model of risk analysis of the tree down installation was ***,by introducing the natural language of expert comprehensive evaluation and combining fuzzy principles,quantitative analysis was carried out,and the fuzzy number was used to calculate the failure probability of a basic event and the occurrence probability of a top ***,through a sensitivity analysis of basic events,the basic events of top events significantly affected were determined,and risk control and prevention measures for the corresponding high-risk factors were proposed for subsea horizontal X-tree down installation.

关键词： subsea horizontal X-tree risk assessment fuzzy fault tree modular risk evaluation model

Significantly Enhanced Melt Memory Effect of Metallocene-made Isotactic Polypropylene Containing Talc

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Chinese Journal of Polymer Science 2024年第2期42卷 213-222,I0008页

作者： Hong-Wen Sun fu-Shan Wang Yan gao fu-Qing Wei Jia-Chun Feng State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai200433China Lanzhou Petrochemical Corporation of PetroChina Lanzhou730060China Lanzhou Petrochemical Research Center Petrochemical Research Institute of PetroChinaLanzhou730060China

The melt memory effect is a widely observed phenomenon in semi-crystalline polymers. In practical applications, various additives are usually introduced into polymers, which may affect their melt memory behavior. In this work, the effect of talc on the melt memory effect of metallocene-made isotactic polypropylene(M-PP) was investigated in detail by using the differential scanning calorimetry. The results indicated that the introduction of talc significantly strengthened the melt memory effect of M-PP. Specifically, the upper limit temperature of Domain II increased from 161 ℃ to 174 ℃, resulting in a substantial widening of the temperature range of Domain IIa from 1 ℃ to 14 ℃. Analysis of the crystal orientation of the M-PP containing talc cooled from various Ts suggested that the remarkably enhanced melt memory effect could be ascribed to the stabilization of oriented nuclei facilitated by talc. This stabilizing effect was likely attributable to the prefreezing effect or the sorption interaction between talc and the M-PP chains.

关键词： Metallocene-made isotactic polypropylene Talc Melt memory effect Crystal orientation

Effect of Al content in molten steel on interaction between MgO-C refractory and SPHC steel

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Journal of Iron and Steel Research International 2024年第4期31卷 838-848页

作者： fu-bin gao fu-ming Wang Xiang Zhang Tian-yu Du Xin-hua Wangg School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Handan Iron and Steel Company Hegang GroupHandan 056015HebeiChina The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina

The effect of Al content in molten steel on the interaction between SPHC steel(0.005-0.068 wt.%Al,and 19×10^(-4)-58×10^(-4)wt.%O)and MgO-C refractory(11.63 wt.%C)was ***-metallic inclusions in the steel were examined at various periods(0,5,15,30,45,and 60 min)as well as the MgO-C interface after 60 min of corrosion at 1600℃.The results show that when MgO-C refractory comes into contact with SPHC steel,the refractory interface consists of three layers arranged from the innermost to the outermost,including the original refractory layer,the dense MgO layer,and the iron infiltration *** carbon in the MgO-C refractories and the Al content in the molten steel undergo a reaction with the MgO in the refractories,resulting in an increase in Mg concentration in the *** Al content in the molten steel from 0.005 to 0.068 wt.%causes a spinel layer to appear at the interface,and the disappearance time of Al_(2)O_(3) inclusions in the steel decreases from 60 to 30 min,while the average MgO content in inclusions ***,controlling the Al content in the molten steel and the smelting duration can help regulate the formation of spinel inclusionsinthe steel.

关键词： MgO-C refractory SPHC steel Inclusion-Spinel Al-killed steel Interfacial reaction

Molecular mechanism of a coastal cyanobacterium Synechococcus *** 7002 adapting to changing phosphate concentrations

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Marine Life Science & Technology 2024年第3期6卷 562-575页

作者： Qiao-Wei Sun Yu gao Jordan Wang Fei-xue fu Cheng-Wen Yong Shuang-Qing Li hai-Long Huang Wei-Zhong Chen Xin-Wei Wang hai-Bo Jiang School of Marine Sciences Ningbo UniversityNingbo 315211China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519080China School of Life Sciences Central China Normal UniversityWuhan 430079China Department of Biological Sciences University of Southern CaliforniaLos AngelesCA 90089USA

Phosphorus concentration on the surface of seawater varies greatly with different environments,especially in *** molecular mechanism by which cyanobacteria adapt to fluctuating phosphorus bioavailability is still *** this study,transcriptomes and gene knockouts were used to investigate the adaptive molecular mechanism of a model coastal cyanobacterium Synechococcus *** 7002 during periods of phosphorus starvation and phosphorus recovery(adding sufficient phosphorus after phosphorus starvation).The findings indicated that phosphorus deficiency affected the photosynthesis,ribosome synthesis,and bacterial motility pathways,which recommenced after phosphorus was *** more,most of the metabolic pathways of cyanobacteria were enhanced after phosphorus recovery compared to the control which was kept in continuous phosphorus replete *** on transcriptome,54 genes potentially related to phosphorusdeficiency adaptation were selected and knocked out individually or in *** was found that five mutants showed weak growth phenotype under phosphorus deficiency,indicating the importance of the genes(A0076,A0549-50,A1094,A1320,A1895)in the adaptation of phosphorus *** mutants were found to grow better than the wild type under phosphorus deficiency,suggesting that the products of these genes(A0079,A0340,A2284–86)might influence the adaptation to phosphorus *** analysis revealed that cyanobacteria exposed to highly fluctuating phosphorus concentrations have more sophisticated phosphorus acquisition *** results elucidated that Synechococcus *** 7002 have variable phosphorus response mechanisms to adapt to fluctuating phosphorus concentration,providing a novel perspective of how cyanobacteria may respond to the complex and dynamic environments.

关键词： Synechococcus sp PCC 7002 Phosphorus fluctuation Cyanobacteria ・Gene knockout Molecular mechanism

Projected changes in extreme snowfall events over the Tibetan Plateau based on a set of RCM simulations

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Atmospheric and Oceanic Science Letters 2024年第5期17卷 3-9页

作者： Yuanhai fu Xuejie gao Climate Change Research Center Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjingChina University of Chinese Academy of Sciences BeijingChina

Extreme snowfall events over the Tibetan Plateau(TP)cause considerable damage to local society and natural *** this study,the authors investigate the projected changes in such events over the TP and its surrounding areas based on an ensemble of a set of 21st century climate change projections using a regional climate model,*** model is driven by five CMIP5 global climate models at a grid spacing of 25 km,under the RCP4.5 and RCP8.5 *** modified ETCCDI extreme indices-namely,SNOWTOT,S1mm,S10mm,and Sx5day-are employed to characterize the extreme snowfall ***4 generally reproduces the spatial distribution of the indices over the region,although with a tendency of *** the projected changes,a general decrease in SNOWTOT is found over most of the TP,with greater magnitude and better cross-simulation agreement over the eastern *** the simulations project an overall decrease in S1mm,ranging from a 25%decrease in the west and to a 50%decrease in the east of the *** S10mm and Sx5day are projected to decrease over the eastern part and increase over the central and western parts of the ***,S10mm shows a marked increase(more than double)with high cross-simulation agreement over the central *** increases in all four indices are found over the Tarim and Qaidam basins,and northwestern China north of the *** projected changes show topographic dependence over the TP in the latitudinal direction,and tend to decrease/increase in low-/high-altitude areas.

关键词： Extreme snowfall Regional climate model Tibetan plateau Climate change

Control of fine particulate nitrate during severe winter haze in“2+26”cities

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Journal of Environmental Sciences 2024年第2期136卷 261-269页

作者： Chuang Qin Xiao fu Tao Wang Jian gao Jiaqi Wang Institute of Environment and Ecology Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Department of Civil and Environmental Engineering Hong Kong Polytechnic UniversityHong Kong 99907China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 10084China

The“2+26”cities,suffering the most severe winter haze pollution,have been the key region for air quality improvement in *** prominent nitrate pollution is one of the most challenging environmental issues in this region,necessitating development of an effective control ***,we use observations,and state-of-the-art model simulations with scenario analysis and process analysis to quantify the effectiveness of the future SO_(2)-NO_(X)-VOC-NH_(3) emission control on nitrate pollution mitigation in“2+26”*** on a serious winter haze episode,we find that limited NO_(X)emission reduction alone in the short-term period is a less effective choice than VOC or NH_3emission reduction alone to decrease nitrate concentrations,due to the accelerated NO_(X)-HNO_(3)conversion by atmospheric oxidants and the enhanced HNO_(3)to NO_(3)^(-)partition by ammonia,although deep NO_(X)emission reduction is essential in the long-term *** synergistic NH_(3) and VOC emission control is strongly recommended,which can counteract the adverse effects of nonlinear photochemistry and aerosol chemical feedback to decrease nitrate *** extra benefits will be reduced if the synergistic NH_(3) and VOC reduction is delayed,and thus reducing emission of multiple precursors is urgently required for the effective control of increasingly severe winter nitrate pollution in“2+26”cities.

关键词： Nitrate Winter haze pollution Emission reduction “2+26”cities

Energy flexibility and resilience analysis of demand-side energy efficiency measures within existing residential houses during cold wave event

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Building Simulation 2024年第7期17卷 1043-1063页

作者： Xiaoyi Zhang fu Xiao Yanxue Li Yi Ran Weijun gao Innovation Institute for Sustainable Maritime Architecture Research and Technology Qingdao University of TechnologyQingdaoChina Department of Building Environment and Energy Engineering The Hong Kong Polytechnic UniversityHong KongChina Faculty of Environmental Engineering The Universityof KitakyushuKitakyushuJapan

Using the behind-meter data,this study applied a comparison and optimization-based framework to evaluate the energy flexibility and resilience of distributed energy resources within existing houses during cold wave *** analysis demonstrates the effectiveness of high envelope insulation level in improving energy resilience,identifies impacts of distributed energy resources on variations of household electricity ***,a 14.6%reduction in the median value of the normalized load of building group with low U-values,implementations of cogeneration system effectively suppressed variations of electricity *** energy performances of on-site generators are evaluated based on high resolution data,energy flexibility of domestic hot water and thermostatically controlled loads were investigated through built demand response *** reveal that electrifying hot water demand offers additional power flexibility,the integration of fuel cell cogeneration system has proven to be an efficient energy resource,enabling on-site generation of both electricity and hot water,substantially reducing grid *** extreme cold event resulted in significant spikes in space heating power *** optimization results demonstrate that reducing the indoor setpoint temperature effectively decreases daily power consumption by approximately 5.0%per degree *** findings help acquire better understanding of interconnections between energy efficiency and resilience of residential energy-efficient measures.

关键词： system modeling energy efficiency energy resilience cold wave thermal comfort