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Experimental and simulation research on hollow AZ31 magnesium alloy three-channel joint by hot extrusion forming with sand mandrel

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Journal of Magnesium and Alloys 2024年第1期12卷 98-109页

作者： Shi Shengnan Wang Hongyu Teng Fei Jiang Lei sun Juncai sun jie Zhang Shunhu Transportation Engineering College Dalian Maritime UniversityDalianLiaoning 106026China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyangLiaoning 110819China Shagang School of Iron and Steel Soochow UniversitySuzhouJiangsu 215021China

Magnesium alloy is one of the lightest metal structural materials.The weight is further reduced through the hollow structure.However,the hollow structure is easily damaged during processing.In order to maintain the hollow structure and to transfer the stresses during the high temperature deformation,the sand mandrel is proposed.In this paper,the hollow AZ31 magnesium alloy three-channel joint is studied by hot extrusion forming.Sand as one of solid granule medium is used to fill the hollow magnesium alloy.The extrusion temperatures are 230℃ and 300℃,respectively.The process parameters(die angle,temperature,bottom thickness,sidewall thickness,edge-to-middle ratio in bottom,bottom shape)of the hollow magnesium alloy are analyzed based on the results of experiments and the finite element method.The results are shown that the formability of the hollow magnesium alloy will be much better when the ratio of sidewall thickness to the bottom thickness is 1:1.5.Also when edge-to-middle ratio in bottom is about 1:1.5,a better forming product can be received.The best bottom shape in these experiments will be convex based on the forming results.The grain will be refined obviously after the extrusion.Also the microstructures will be shown as streamlines.And these lines will be well agreement with the mold in the corner.

关键词： AZ31 magnesium alloy Three-channel joint Sand Experiments and the finite element Die angle

Assessment of the Characteristics of Demersal Fish Communities Using Species-and Trait-Based Approaches in the Coastal Habitats Along Rongcheng Bay,Shandong Peninsula,China

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Journal of Ocean University of China 2024年第3期23卷 786-796页

作者： YUAN Shunjie sun Xin TU Zhong sun jie WANG Xianning ZHANG Peidong Key Laboratory of Mariculture(Ocean University of China) Ministry of EducationQingdao 266003China Shandong Fisheries Development and Resource Conservation Center Yantai 264003China

Biodiversity declines have motivated many studies on the relationship between species diversity and ecosystem functioning.In this study,we described the spatial-temporal characteristics of demersal fish communities along a coastal habitat in Rongcheng Bay,Shandong Peninsula,China with both species-based and biological trait-based approaches.The field survey was carried out monthly using traps from April to October of 2018,and divided into three seasons(spring:April and May;summer:June,July and August;autumn:September,October and November).The study area included five distinct habitats:seagrass bed,natural rocky reef,bare sand,artificial reef together with natural rocky reef,and artificial reef together with bare sand.We analyzed the fish communities with three taxonomic diversity indices,including Shannon-Wiener,Simpson,and Pielou Evenness,as well as four functional diversity indices,including FRic,FEve,FDiv,and FDis,based on 7 functional groups which are categorized into 27 traits.The results showed that there were no significant differences in taxonomic diversity indices among different habitats in the three seasons.However,significant differences were found in the functional richness of fish communities among different habitats in three seasons.Seagrass bed represented the highest functional richness in spring and autumn.This study demonstrates that seagrass bed is very important in enhancing the functional diversity of fish communities in a complex habitat.The study also indicates that the combination of taxonomic diversity and functional diversity will provide a more detailed description of the characteristics of fish communities.

关键词： complex habitat biological traits biodiversity fish communities

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Dynamic response mechanism and precursor characteristics of gneiss rockburst under different initial burial depths

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Journal of Mountain Science 2024年第3期21卷 1004-1018页

作者： LIU Dongqiao sun jie MENG Wen HE Manchao ZHANG Chongyuan LI Ran CAO Binghao State Key Laboratory for Tunnel Engineering China University of Mining and TechnologyBeijing 100083China Key Laboratory of Active Tectonics and Geological Safety Ministry of Natural ResourcesInstitute of GeomechanicsChinese Academy of Geological SciencesBeijing 100081China School of Mechanics and Civil Engineering China University of Mining and TechnologyBeijing 100083China

To investigate the influence mechanism of geostress on rockburst characteristics,three groups of gneiss rockburst experiments were conducted under different initial geostress conditions.A high-speed photography system and acoustic emission(AE)monitoring system were used to monitor the entire rockburst process in real time.The experimental results show that when the initial burial depth increases from 928 m to 1320 m,the proportion of large fracture scale in rockburst increases by 154.54%,and the AE energy increases by 565.63%,reflecting that the degree and severity of rockburst increase with the increase of burial depth.And then,two mechanisms are proposed to explain this effect,including(i)the increase of initial geostress improves the energy storage capacity of gneiss,and then,the excess energy which can be converted into kinetic energy of debris ejection increases,consequently,a more pronounced violent ejection phenomenon is observed at rockburst;(ii)the increase of initial geostress causes more sufficient plate cracks of gneiss after unloading ofσh,which provides a basis for more severe ejection of rockburst.What’s more,a precursor with clear physical meaning for rockburst is proposed under the framework of dynamic response process of crack evolution.Finally,potential value in long term rockburst warning of the precursor obtained in this study is shown via the comparison of conventional precursor.

关键词： Traffic Engineering Gneiss Rockburst Crack propagation Excess energy Precursor characteristic

A Quasi-Linear Relationship between Planetary Outgoing Longwave Radiation and Surface Temperature in a Radiative-Convective-Transportive Climate Model of a Gray Atmosphere

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Advances in Atmospheric Sciences 2024年第1期41卷 8-18页

作者： jie sun Michael SECOR Ming CAI Xiaoming HU Department of Earth Oceanand Atmospheric ScienceFlorida State UniversityTallahasseeFlorida 32304USA School of Atmospheric Sciences Sun Yat-sen University and Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies Zhuhai 519082China

In this study,we put forward a radiative-convective-transportive energy balance model of a gray atmosphere to examine individual roles of the greenhouse effect of water vapor,vertical convection,and atmospheric poleward energy transport as well as their combined effects for a quasi-linear relationship between the outgoing longwave radiation(OLR)and surface temperature(T_(S)).The greenhouse effect of water vapor enhances the meridional gradient of surface temperature,thereby directly contributing to a quasi-linear OLR-T_(S) relationship.The atmospheric poleward energy transport decreases the meridional gradient of surface temperature.As a result of the poleward energy transport,tropical(high-latitude)atmosphere-surface columns emit less(more)OLR than the solar energy input at their respective locations,causing a substantial reduction of the meridional gradient of the OLR.The combined effect of reducing the meridional gradients of both OLR and surface temperature by the poleward energy transport also contributes to the quasi-linear OLR-T_(S) relationship.Vertical convective energy transport reduces the meridional gradient of surface temperature without affecting the meridional gradient of OLR,thereby suppressing part of the reduction to the increasing rate of OLR with surface temperature by the greenhouse effect of water vapor and poleward energy transport.Because of the nature of the energy balance in the climate system,such a quasi-linear relationship is also a good approximation for the relationship between the annual-mean net downward solar energy flux at the top of the atmosphere and surface temperature.

关键词： outgoing longwave radiation greenhouse effect poleward energy transport

Monocyte and macrophage function in respiratory viral infections

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Animal Diseases 2024年第1期4卷 40-47页

作者： Mohd Arish jie sun Beirne B.Carter Center for Immunology Research University of VirginiaCharlottesvilleVA 22908USA Division of Infectious Disease and International Health Department of MedicineUniversity of VirginiaCharlottesvilleVA 22908USA

Pulmonary macrophages,such as tissue-resident alveolar and interstitial macrophages and recruited monocyte-derived macrophages,are the major macrophages present in the lungs during homeostasis and diseased conditions.While tissue-resident macrophages act as sentinels of the alveolar space and play an important role in maintaining homeostasis and immune regulation,recruited macrophages accumulate in the respiratory tract after acute viral infections.Despite sharing similar anatomical niches,these macrophages are distinct in terms of their origins,surface marker expression,and transcriptional profiles,which impart macrophages with distinguished characteristics in physi-ological and pathophysiological conditions.In this review,we summarize the current view on these macrophage populations,their shared functions,and what makes them distinct from each other in the context of homeostasis andrespiratoryviral infections.

关键词： Alveolar macrophages Interstitial macrophages Monocytes derived macrophages Viral infection IAV RSV SARS-COV-2

Exploring formation mechanism and source attribution of ozone during the 2019 Wuhan Military World Games:Implications for ozone control strategies

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Journal of Environmental Sciences 2024年第2期136卷 400-411页

作者： Lei Zhang Lili Wang Runyu Wang Nan Chen Yuan Yang Ke Li jie sun Dan Yao Yuesi Wang Minghui Tao Yang sun Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China University of the Chinese Academy of Sciences Beijing 100049China Hubei Ecological Environment Monitoring Center Station Wuhan 430072China Guizhou Research and Designing Institute of Environmental Sciences Guizhou Academy of Environmental Science and DesignGuiyang 550081China Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science and TechnologyNanjing 210044China School of Environment Key Laboratory for Yellow River and Huai River Water Environment and Pollution ControlMinistry of EducationHenan Normal UniversityXinxiang 453007China Key Laboratory of Regional Ecology and Environmental Change School of Geography and Information EngineeringChina University of GeosciencesWuhan 430074China

A series of emission reduction measures were conducted in Wuhan,Central China,to ensure good air quality during the 7th Military World Games(MWG)in October 2019.To better understand the implications for ozone(O_(3))pollution control strategies,we applied integrated analysis approaches based on the de-weathered statistical model,parameterization methods,chemical box model,and positive matrix factorization model.During the MWG,concentrations of O_(3),NO_x,and volatile organic compound(VOCs),OFP(O_(3)formation potential),L_(OH)(OH radical loss rate)were 83μg/m^(3),43μg/m^(3),26 ppbv,188μg/m^(3),and 3.9 s^(-1),respectively,which were 26%,18%,3%,15%,and 13%lower than pre-MWG values and 6%,39%,30%,33%,and 50%lower than post-MWG values,respectively.After removing meteorological influence,O_(3)and its precursors during the MWG decreased largely compared with post-MWG values,and only O_(3),NO_(2),and oxygenated VOCs(OVOCs)declined compared with pre-MWG values,which revealed the emission reduction measures during the MWG played an important role for O_(3)decline.For six VOCs sources,the mass contributions of biomass burning and solvents usage during the MWG decreased largely compared with pre-MWG values.O_(3)production was sensitive to VOCs and the key species were aromatics,OVOCs,and alkenes,which originated mainly from solvents usage,biomass burning,industrial-related combustion,and vehicle exhaust.Decreasing O_(3)concentration during the strict control was mainly caused by OVOCs reduction due to biomass burning control.Generally,the O_(3)abatement strategies of Wuhan should be focused on the mitigation of high-reactivity VOCs.

关键词： VOCs Ozone Wuhan Military World Games Source apportionment Relative incremental reactivity Random forest

Interfacial growth of N,S-codoped mesoporous carbon onto biomass-derived carbon for superior potassium-ion storage

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Nano Research 2024年第4期17卷 2619-2627页

作者： Na Huang Cheng Tang Hao Jiang jie sun Aijun Du Haijiao Zhang Institute of Nanochemistry and Nanobiology School of Environmental and Chemical EngineeringShanghai UniversityShanghai 200444China School of Chemistry and Physics and Centre for Materials Science Queensland University of TechnologyBrisbaneQLD 4001Australia Shanghai Engineering Research Center of Hierarchical Nanomaterials Frontiers Science Center for Materiobiology and Dynamic ChemistrySchool of Materials Science and EngineeringEast China University of Science and TechnologyShanghai 200237China

Carbonaceous materials have been recognized as one of the most promising anode materials for potassium-ion batteries(PIBs)due to their abundant raw materials,controllable structure,superior conductivity,and good chemical inertness.However,the large radius of K ions and the low potassium content of intercalation compounds result in the sluggish storage kinetics and low reversible capacity of carbon anodes.In this work,we present a unique heteroatom-doped carbon composite(denoted as NS-MC/SC)through a facile interfacial assembly route and simple heat-treatment process,where NS-MC is well grafted onto the biomass-derived spore carbon(SC).This unique structural design endows it with abundant mesoporous channels,expanded layer spacing,and highly doped N and S.With these merits,the NS-MC/SC anode in PIBs exhibits a high reversible capacity of 350.4 mAh·g^(-1) at 100 mA·g^(-1) after 300 cycles,and an outstanding cycling stability.Besides,in-situ Raman spectra further verify the high reversibility of K ions insertion/extraction.Importantly,theoretical simulations also reveal that the N,S dual-doping is an efficient approach for improving the potassium-ion storage performance of NS-MC/SC.

关键词： mesoporous carbon(MC) biomass-derived carbon(BC) N S co-doping interfacial assembly potassium-ion batteries(PIBs)

Post-acute ischemic stroke hyperglycemia aggravates destruction of the blood-brain barrier

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Neural Regeneration Research 2024年第6期19卷 1344-1350页

作者： Tianqi Xu Jianhong Yang Yao Xu Xiaofeng Wang Xiang Gao jie sun Chenhui Zhou Yi Huang Department of Neurology The First Affiliated Hospital of Ningbo University Department of General Surgery The First Affiliated Hospital of Ningbo University Department of Neurosurgery The First Affiliated Hospital of Ningbo University Key Laboratory of Precision Medicine for Atherosclerotic Diseases of Zhejiang Province

Post-acute ischemic stroke hyperglycemia increases the risk of hemorrhagic transformation, which is associated with blood-brain barrier disruption. Brain microvascular endothelial cells are a major component of the blood-brain barrier. Intercellular mitochondrial transfer has emerged as a novel paradigm for repairing cells with mitochondrial dysfunction. In this study, we first investigated whether mitochondrial transfer exists between brain microvascular endothelial cells, and then investigated the effects of post-acute ischemic stroke hyperglycemia on mitochondrial transfer between brain microvascular endothelial cells. We found that healthy brain microvascular endothelial cells can transfer intact mitochondria to oxygen glucose deprivation-injured brain microvascular endothelial cells. However, post-oxygen glucose deprivation hyperglycemia hindered mitochondrial transfer and exacerbated mitochondrial dysfunction. We established an in vitro brain microvascular endothelial cell model of the blood-brain barrier. We found that post-acute ischemic stroke hyperglycemia reduced the overall energy metabolism levels of brain microvascular endothelial cells and increased permeability of the blood-brain barrier. In a clinical study, we retrospectively analyzed the relationship between post-acute ischemic stroke hyperglycemia and the severity of hemorrhagic transformation. We found that post-acute ischemic stroke hyperglycemia serves as an independent predictor of severe hemorrhagic transformation. These findings suggest that post-acute ischemic stroke hyperglycemia can aggravate disruption of the blood-brain barrier by inhibiting mitochondrial transfer.

关键词： acute ischemic stroke blood-brain barrier brain microvascular endothelial cells mitochondrial transfer stress hyperglycemia

Experimental study on the effect of water absorption level on rockburst occurrence of sandstone

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 136-152页

作者： Dongqiao Liu jie sun Pengfei He Manchao He Binghao Cao Yuanyuan Yang State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology(Beijing)Beijing100083China School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)Beijing100083China Institute for Deep Underground Science and Engineering China University of Mining and Technology(Beijing)Beijing100083China

To investigate the mechanism of rockburst prevention by spraying water onto the surrounding rocks,15 experiments are performed considering different water absorption levels on a single face.High-speed photography and acoustic emission(AE)system are used to monitor the rockburst process.The effect of water on sandstone rockburst and the prevention mechanism of water on sandstone rockburst are analyzed from the perspective of energy and failure mode.The results show that the higher the ab-sorption degree,the lower the intensity of the rockburst after absorbing water on single side of sand-stone.This is reflected in the fact that with the increase in the water absorption level,the ejection velocity of rockburst fragments is smaller,the depth of the rockburst pit is shallower,and the AE energy is smaller.Under the water absorption level of 100%,the magnitude of rockburst intensity changes from medium to slight.The prevention mechanism of water on sandstone rockburst is that water reduces the capacity of sandstone to store strain energy and accelerates the expansion of shear cracks,which is not conducive to the occurrence of plate cracking before rockburst,and destroys the conditions for rockburst incubation.

关键词： Rockburst Water Prevention effect Crack evolution