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The effects of deformation parameters and cooling rates on the aging behavior of AZ80+0.4%Ce

Journal of Magnesium and Alloys 2024年第2期12卷 639-658页

作者： Yongbiao Yang Jinxuan Guo Cuiying Wang Ting Yan Zhang Wenxuan Jiang Zhimin Zhang Qiang Wang guojun li Jun Wang College of Materials Science and Engineering North University of ChinaLane 3Xueyuan RoadTaiyuanShanxiChina030051 State Key Laboratory of Advanced Stainless Steel Materials Taiyuan Iron Steel(Group)Co.Ltd.Taiyuan 030003China Technology Center Shanxi Taigang Stainless Steel Co.Ltd.Taiyuan 030003China

The extruded AZ80+0.4%Ce magnesium alloy was twisted in the temperature range of 300-380℃by using a Gleeble 3500 thermal simulation test machine with a torsion unit.The deformed cylindrical specimens were cooled at a cooling rate of 10℃/s or 0.1℃/s,respectively,and aged at 170℃.The microstructure analysis results showed that the grain size decreased with increasing specimen radial position from center(SRPC),and that the strong initial basal texture of the extruded magnesium alloy was weakened.Both continuous and discontinuous dynamic recrystallization mechanisms were involved in contributing to the grain refinement for all specimens investigated.And a novel extension twinning induced dynamic recrystallization mechanism was proposed for specimen deformed at 300℃.For the specimens deformed at 300℃and 340℃followed by a slow cooling rate(0.1℃/s),precipitates of various shapes(β-Mg_(17)Al_(12)),with the dominant precipitates being on the grains boundaries,appeared on the surface section.For specimen deformed at 380℃,lamellar precipitates(LPS)in the interiors of the grains were predominant.After aging,the LPS still dominated for specimens twisted at 380℃;however,the LPS gradually decreased with decreasing deformation temperatures from 380℃to 300℃.Dynamically precipitatedβ,especially those decorating the grain boundaries,changed the competition pictures for the LPS and precipitates of other shapes after aging.Interestingly,LPS dominated the areas for the center section of the specimens after aging regardless of deformation temperatures.Low temperature deformation with high SRPC followed by rapid cooling rate increased the micro hardness of the alloy after aging due to refined grain,reduced precipitates size,decreased lamellar spacing as well as strain hardening.

关键词： AZ80+0.4%Ce magnesium alloy Hot torsion Deformation parameters Cooling rate Aging Micro hardness

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Status and trends in the stability of the three largest ice shelves in Antarctica

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Science China Earth Sciences 2024年第8期 2615-2632页

作者： Rongxing li guojun li Lu AN Menglian XIA Da LV Yuan CHENG Aiguo ZHAO Tian CHANG Xiangbin CUI Shengkai ZHANG Shijie liU Yixiang TIAN Weian WANG Center for Spatial Information Science and Sustainable Development Applications Tongji University College of Surveying and Geo-informatics Tongji University Postdoctoral Research Station of Shanghai Surveying and Mapping Institute Key Laboratory of Spatial-temporal Big Data Analysis and Application of Natural Resources in Megacities Institute for Conservation of Cultural Heritage School of Cultural Heritage and Information Management Shanghai University Polar Research Institute of China Chinese Antarctic Center of Surveying and Mapping Wuhan University

The Ross, Filchner-Ronne, and Amery ice shelves are the three largest ice shelves in Antarctica, playing a crucial role in supporting the Antarctic ice sheet. However, current studies on the stability of the three largest ice shelves primarily focus on singular or limited factors, lacking a comprehensive assessment of multiple parameters. To systematically and in-depth study the stability and trend of the three largest ice shelves, we comprehensively collected and analyzed key parameters, including elevation changes, basal melting, surface meltwater, major rifts propagation rate, suture zones, ice front area change rate,grounding lines, ice velocity, and mass balance. Additionally, we selected the collapsed Larsen B Ice Shelf(LBIS), the rapidly changing and structurally weakened Pine Island Ice Shelf(PIIS), and the accelerating Totten Ice Shelf(TIS) as reference ice shelves. By comparing and analyzing the key parameters between these reference ice shelves and the three largest ice shelves, we find the status and trends in the stability of the latter. Our findings reveal that most key parameters of the three largest ice shelves present relatively minor variations compared to those of the reference ice shelves. Specifically, 50% of the parameters are smaller than those of the accelerating TIS, 88% are smaller than those of the rapidly changing PIIS, and all parameters are smaller than those of the collapsed LBIS. Furthermore, after analyzing parameters that are not smaller than those of the TIS, it is observed that they remain in a stable state. Hence, the three largest ice shelves are currently undergoing natural changes that do not threaten their stability in the short term. Nevertheless, the evolution of the ice shelves under global climate change remains uncertain,making long-term observation and monitoring essential to assess their impact on sea level rise.

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A Survey on the Evolution of Bootkits Attack and Defense Techniques

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China Communications 2024年第1期21卷 102-130页

作者： Yilin Zhou guojun Peng Zichuan li Side liu Key Laboratory of Aerospace Information Security and Trust Computing Ministry of EducationWuhan 430072China School of Cyber Science and Engineering Wuhan UniversityWuhan 430072China

According to the boot process of modern computer systems,whoever boots first will gain control first.Taking advantage of this feature,a malicious code called bootkit can hijack the control before the OS bootloader and bypass security mechanisms in boot process.That makes bootkits difficult to detect or clean up thoroughly.With the improvement of security mechanisms and the emergence of UEFI,the attack and defense techniques for bootkits have constantly been evolving.We first introduce two boot modes of modern computer systems and present an attack model of bootkits by some sophistical samples.Then we discuss some classic attack techniques used by bootkits from their initial appearance to the present on two axes,including boot mode axis and attack phase axis.Next,we evaluate the race to the bottom of the system and the evolution process between bootkits and security mechanisms.At last,we present the possible future direction for bootkits in the context of continuous improvement of OS and firmware security mechanisms.

关键词： bootkit hook legacy BIOS security mechanisms UEFI

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Wettability regulation from superhydrophilic to superhydrophobic via nanosecond laser ablation

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Science China Technological Sciences 2024年第6期67卷 1829-1841页

作者： CHEN Zhi WU ZhiCheng ZHANG guojun li DongHui HAN Fenglin State Key Laboratory of Precision Manufacturing for Extreme Service Performance College of Mechanical and Electrical EngineeringCentral South University Guangdong Provincial Key Laboratory of Manufacturing Equipment Digitization Guangdong HUST Industrial Technology Research Institute China Harzone Industry Corp. Ltd.

Metal surfaces play a crucial role in numerous applications, from self-cleaning and anti-icing to anti-fogging and oil-water separation. The regulation of their wettability is essential to enhance their performance in these areas. This paper proposes a multi-state regulation method for metal surface wettability, leveraging nanosecond laser ablation. By creating non-uniform microstructures on a metal surface, the contact area between the solid and liquid phases can be increased, resulting in the attainment of superhydrophilic properties(contact angle(CA), ranging from 4.6° to 8.5°). Conversely, the construction of uniform microstructures leads to a decreased solid-liquid contact area, thereby rendering the metal surface hydrophilic(CA=12.2°–53°). Furthermore, through heat treatment on a surface with uniform microstructures, organic matter adsorption can be promoted while simultaneously reducing surface energy. This process results in the metal surface acquiring hydrophobic properties(CA=92.1°–133.5°), facilitated by the “air cushion effect.” Building on the hydrophobic surface, stearic acid modification can further reduce surface energy, ultimately bestowing the metal surface with superhydrophobic properties(CA=150.1°–152.7°, and sliding angle=3.8°). Performance testing has validated the durability and self-cleaning effectiveness of the fabricated superhydrophobic surface while also highlighting the excellent anti-fog performance of the superhydrophilic surface.These findings strongly indicate the immense potential of these surfaces in various engineering applications.

关键词： nanosecond laser ablation surface wettability superhydrophobic superhydrophilic

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Effects of zero-valent iron added in the flooding or drainage process on cadmium immobilization in an acid paddy soil

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Journal of Environmental Sciences 2024年第4期138卷 19-31页

作者： Hanbing Meng Shiwen Hu Zebin Hong Wenting Chi guojun Chen Kuan Cheng QiWang Tongxu liu Fangbai li Kexue liu Yang Yang Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640China National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and ManagementInstitute of Eco-environmental and Soil SciencesGuangdong Academy of SciencesGuangzhou 510650China School of Resources and Planning Guangzhou Xinhua UniversityGuangzhou 510310China University of Chinese Academy of Sciences Beijing 100049China

Zero-valent iron(ZVI)is a promising material for the remediation of Cd-contaminated paddy soils.However,the effects of ZVI added during flooding or drainage processes on cadmium(Cd)retention remain unclear.Herein,Cd-contaminated paddy soil was incubated for 40days of flooding and then for 15 days of drainage,and the underlying mechanisms of Cd immobilization coupled with Fe/S/N redox processes were investigated.The addition of ZVI to the flooding process was more conducive to Cd immobilization.Less potential available Cd was detected by adding ZVI before flooding,which may be due to the increase in paddy soil pH and newly formed secondary Fe minerals.Moreover,the reductive dissolution of Fe minerals promoted the release of soil colloids,thereby increasing significantly the surface sites and causing Cd immobilization.Additionally,the addition of ZVI before flooding played a vital role in Cd retention after soil drainage.In contrast,the addition of ZVI in the drainage phase was not conducive to Cd retention,which might be due to the rapid decrease in soil pH that inhibited Cd adsorption and further immobilization on soil surfaces.The findings of this study demonstrated that Cd availability in paddy soil was largely reduced by adding ZVI during the flooding period and provide a novel insight into the mechanisms of ZVI remediation in Cd-contaminated paddy soils.

关键词： Paddy soil Zero-valent iron Cadmium Flooding and drainage Remediation

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Carotenoid isomerase regulates rice tillering and grain productivity by its biosynthesis pathway

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Journal of Integrative Plant Biology 2024年第2期66卷 172-175页

作者： Chaoqing Ding Zhengji Shao Yuping Yan Guangheng Zhang Dali Zeng li Zhu Jiang Hu Zhenyu Gao guojun Dong Qian Qian Deyong Ren State Key Laboratory of Rice Biology and Breeding ChinaNational Rice Research InstituteHangzhou 310006China

Tillers are unique inflorescence-like branches in grasses,and their number determines the panicle number,plant architecture,and yield(Shang et al.,2021).Tiller formation mainly undergoes axillary meristem(AM)initiation and tiller bud outgrowth(Wang et al.,2018;Yan et al.,2023).The rice(Oryza sativa)KNOX gene OSH1 is expressed in AMs,and an osh1 mutant produces fewer tillers(Tanaka et al.,2015).

关键词： sativa Oryza panicle

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Soft Template-Induced Porous Polyvinylidene Fluoride Membrane for Vanadium Flow Batteries

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天津大学学报:英文版 2023年第4期29卷 284-292页

作者： Dingqin Shi Chunyang li Zhizhang Yuan guojun li Metal-Air New Energy Batteries Key Laboratory of liaoning Province Dalian Jiaotong UniversityDalian 116028China Division of Energy Storage Dalian National Laboratory for Clean Energy(DNL)Dalian Institute of Chemical PhysicsChinese Academy of Sciences116023 DalianChina

Vanadium flow batteries(VFBs)are considered ideal for grid-sc ale,long-duration energy storage applications owing to their decoupled output power and storage capacity,high safety,efficiency,and long cycle life.However,the widespread adoption of VFB s is hindered by the use of expensive Nafion membranes.Herein,we report a soft template-induced method to develop a porous polyvinylidene fluoride(PVDF)membrane for VFB applications.By incorporating water-soluble and flexible polyethylene glycol(PEG 400)as a soft template,we induced the aggregation of hydrophilic sulfonated poly(ether ether ketone),resulting in phase separation from the hydrophobic PVDF polymer during membrane formation.This process led to the creation of a porous PVDF membrane with controllable morphologies determined by the polyethylene glycol content in the cast solution.The optimized porous PVDF membrane enabled a stable VFB performance for 200 cycles at a current density of 80 mA/cm^(2),and the VFB exhibited a Coulombic efficiency of 95.2%and a voltage efficiency of 87.8%.These findings provide valuable insights for the development of highly stable membranes for VFB applications.

关键词： Energy storage Vanadium flow battery Porous polyvinylidene fluoride membrane Soft template-induced phase separation

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Neural stem cell-derived exosomes promote mitochondrial biogenesis and restore abnormal protein distribution in a mouse model of Alzheimer's disease

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Neural Regeneration Research 2024年第7期19卷 1593-1601页

作者： Bo li Yujie Chen Yan Zhou Xuanran Feng guojun Gu Shuang Han Nianhao Cheng Yawen Sun Yiming Zhang Jiahui Cheng Qi Zhang Wei Zhang Jianhui liu Department of Radiology Renji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghaiChina Morphology and Spatial Multi-Omics Technology Platform Shanghai Institute of Nutrition and HealthChinese Academy of SciencesShanghaiChina Department of Anesthesiology Tongji HospitalSchool of MedicineTongji UniversityShanghaiChina Department of Blood Transfusion Huashan HospitalFudan UniversityShanghaiChina

Mitochondrial dysfunction is a hallmark of Alzheimer’s disease.We previously showed that neural stem cell-derived extracellular vesicles improved mitochondrial function in the cortex of AP P/PS1 mice.Because Alzheimer’s disease affects the entire brain,further research is needed to elucidate alterations in mitochondrial metabolism in the brain as a whole.Here,we investigated the expression of several important mitochondrial biogenesis-related cytokines in multiple brain regions after treatment with neural stem cell-derived exosomes and used a combination of whole brain clearing,immunostaining,and lightsheet imaging to clarify their spatial distribution.Additionally,to clarify whether the sirtuin 1(SIRT1)-related pathway plays a regulatory role in neural stem cell-de rived exosomes interfering with mitochondrial functional changes,we generated a novel nervous system-SIRT1 conditional knoc kout AP P/PS1mouse model.Our findings demonstrate that neural stem cell-de rived exosomes significantly increase SIRT1 levels,enhance the production of mitochondrial biogenesis-related fa ctors,and inhibit astrocyte activation,but do not suppress amyloid-βproduction.Thus,neural stem cell-derived exosomes may be a useful therapeutic strategy for Alzheimer’s disease that activates the SIRT1-PGC1αsignaling pathway and increases NRF1 and COXIV synthesis to improve mitochondrial biogenesis.In addition,we showed that the spatial distribution of mitochondrial biogenesis-related factors is disrupted in Alzheimer’s disease,and that neural stem cell-derived exosome treatment can reverse this effect,indicating that neural stem cell-derived exosomes promote mitochondrial biogenesis.

关键词： Alzheimer’s disease mitochondrial biogenesis neural stem cell-derived exosome SIRT1-PGC1α regional brain distribution whole brain clearing and imaging

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Construction of 3D/2D indium vanadate /graphite carbon nitride with nitrogen defects Z-scheme heterojunction for improving photocatalytic carbon dioxide reduction

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Journal of Materials Science & Technology 2023年第23期154卷 129-139页

作者： Mingyi Yu Jianbo Wang guojun li Shule Zhang Qin Zhong School of Chemistry and Chemical Engineering Nanjing University of Science and TechnologyNanjing 210094China

Indium vanadate (InVO4 ) possesses excellent potential in photocatalytic carbon dioxide (CO_(2) ) reduction, but further modifications of reducing charge recombination and increasing active sites are still needed. Herein, InVO4 /g-C3 N4 (InVO-CN) heterojunction composite photocatalysts were prepared via in situ formation of InVO4 nanoparticles on the lamellar structure of graphite carbon nitride (g-C3 N4 ) containing nitrogen (N) defects. Among these composites, 30% InVO-CN showed the best photoreduction performance for CO_(2) at normal temperature and pressure without sacrificial agent (carbon monoxide, CO: 20.14 μmol g–1 h–1;methane, CH4 : 3.46 μmol g–1 h–1 ), which were 1.8 and 2.8 times higher than these of pure g-C3 N4 and InVO4 . The excellent performance could be attributed to the enhancement of CO_(2) adsorption, and most importantly, the enhanced charge carrier separation and reduction capacity induced by the formation of Z-scheme heterojunction between InVO4 and g-C3 N4 . In this work, intimate heterojunction interfaces between materials were formed by introducing g-C3 N4 with defects in InVO4 , which provides a promising modification scheme.

关键词： Z-scheme heterojunction CO_(2)photoreduction g-C3N4,InVO4

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Some recent advances in remote sensing-based monitoring of changes in the Greenland Ice Sheet

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Advances in Polar Science 2024年第2期35卷 275-280页

作者： FENG Tiantian JIA Jinyu WANG Wei YU Zeran liU Xingchen li guojun GU Yuanyuan li Rongxing The Center for Spatial Information Science and Sustainable Development Applications Tongji UniversityShanghai 200092China College of Surveying and Geo-Informatics Tongji UniversityShanghai 200092China College of Electronic Science and Technology National University of Defense TechnologyChangsha 410073China

The mass balance of the Greenland Ice Sheet(GrIS)plays a crucial role in global sea level change.Since the 1960s,remote sensing missions have been providing extensive and continuous observation data for change monitoring of the GrIS.In this paper,we present our recent research results from remote sensing-based GrIS change monitoring.First,historical satellite data are processed and used to fill data gaps and are combined with existing partial maps,completing an ice velocity map of the GrIS from the 1960s to 1980s.This map provides valuable data for estimating the historical mass balance of Greenland.Second,the monthly gravimetry-based mass balance of the GrIS from 2002 to 2020 is estimated by combining Gravity Recovery and Climate Experiment(GRACE)and GRACE Follow On(GRACE-FO)data.It is found that the GrIS has lost a total mass of approximately 4443±75 Gt during this period.Third,based on Global Land Ice Measurements from Space(GliMS),an updated Greenland glacier inventory is achieved utilizing data collected between 2006 and 2020.This inventory provides more detailed and up-to-data glacier boundaries of Greenland.Overall,these advances provide essential data support for estimating the mass balance of the GrIS,contributing to the advancement of research on global sea level change.

关键词： Greenland Ice Sheet remote sensing change monitoring ice velocity satellite gravimetry glacier inventory

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