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Microstructure Evolution and Mechanical Properties of Friction Stir Welded Al-Cu-Li Alloy

Acta Metallurgica Sinica(English Letters) 2024年第5期37卷 855-871页

作者： Peng Chen Wenhao Chen jiaxin Chen Zhiyu Chen Yang Tang ge Liu Bensheng Huang Zhiqing Zhang School of New Energy and Materials Southwest Petroleum UniversityChengdu 610500China Sichuan Provincial Engineering Research Center of Advanced Materials Manufacturing Technology for Shale Gas High-Efficient Exploitation Southwest Petroleum UniversityChengdu 610500China College of Materials Science and Engineering Chongqing UniversityChongqing 400045China School of Mechatronic Engineering Southwest Petroleum UniversityChengdu 610500China School of Robot Engineering Yangtze Normal UniversityChongqing 408100China

The investigation concentrates on friction stir welded(FSW)Al-Cu-Li alloy concerning its local microstructural evolution and mechanical properties.The grain features were characterized by electron back scattered diffraction(EBSD)technology,while precipitate characterization was conducted by using transmission electron microscopy(TEM)aligned along[011]Al and[001]Al zone axes.The mechanical properties are evaluated through micro-hardness and tensile testing.It can be found that nugget zones exhibit finely equiaxed grains evolved through complete dynamic recrystallization(DRX),primarily occurring in continuous dynamic recrystallization(CDRX)and discontinuous dynamic recrystallization(DDRX).In the thermal-mechanically affected zone(TMAZ),numerous sub-structured grains,exhibiting an elongated morphology,were created due to partial DRX,signifying the dominance of CDRX,DDRX,and geometric dynamic recrystallization(GDRX)in this region.T_(1)completely dissolves in the nugget zone(NZ)leading to the formation of Guinier-Preston zones and increase ofδ′,β′and S′.Conversely,T_(1)partially solubilizes in TMAZ,the lowest hardness zone(LHZ)and heat affected zone(HAZ),and the residual T_(1)undergoes marked coarsening,revealing various T_(1)variants.The solubilization and coarsening of T_(1)are primary contributors to the degradation of hardness and strength.θ′primarily dissolves and coarsens in NZ and TMAZ,whilst this precipitate largely coarsens in HAZ and LHZ.σ,TB,grain boundary phases(GBPs)and precipitate-free zone(PFZ)are newly generated during FSW.σexists in the TMAZ,LHZ and HAZ,whereas TB nucleates in NZ.GBPs and PFZ mostly develop in LHZ and HAZ,which can cause strain localization during tensile deformation,potentially leading to LHZ joint fracture.

关键词： Al-Cu-Li alloy Friction stir welding Microstructure evolution Mechanical properties

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Study on site selection planning of urban electric vehicle charging station

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High Technology Letters 2024年第1期30卷 75-84页

作者：刘娜 CHENG jiaxin DUAN Yukai School of Business Shanghai Dianji UniversityShanghai201306 P.R.China

The large-scale development of electric vehicles(EVs)requires numerous charging stations to serve them,and the charging stations should be reasonably laid out and planned according to the charging demand of electric vehicles.Considering the costs of both operators and users,a site selection model for optimal layout planning of charging stations is constructed,and a queuing theory approach is used to determine the charging pile configuration to meet the charging demand in the planning area.To solve the difficulties of particle swarm global optimization search,the improved random drift particle swarm optimization(IRDPSO)and Voronoi diagram are used to jointly solve for the optimal layout of electric vehicles.The final arithmetic analysis verifies the feasibility and practicality of the model and algorithm,and the results show that the total social cost is minimized when the charging station is 9,the location of the charging station is close to the center of gravity and the layout is reasonable.

关键词： charging station electric vehicle(EV) improved random drift particle swarm optimization(IRDPSO) optimal planning

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tRNA-derived small RNAs:Mechanisms and potential roles in cancers

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genes & Diseases 2022年第6期9卷 1431-1442页

作者： Yao Wang Qiuyan Weng jiaxin ge Xinjun Zhang Junming Guo Guoliang Ye Department of Biochemistry and Molecular Biology And Zhejiang Key Laboratory of PathophysiologyMedical School of Ningbo UniversityNingboZhejiang 315211PR China Department of Gastroenterology The Affiliated Hospital of Ningbo University School of MedicineNingboZhejiang 315020PR China Institute of Digestive Diseases of Ningbo University NingboZhejiang 315020PR China

Transfer RNAs(tRNAs)are essential for protein synthesis.Mature or pre-tRNAs may be cleaved to produce tRNA-derived small RNAs(tsRNAs).tsRNAs,divided into tRNA-derived stress-induced RNA(tiRNAs)and tRNA-derived fragments(tRFs),play versatile roles in a number of fundamental biological processes.tsRNAs not only play regulatory roles in gene silencing,RNA stability,reverse transcription,and translation,but are also closely related to cell proliferation,migration,cell cycle,and apoptosis.Their abnormal expression is associated with the occurrence and development of various human diseases,especially cancer.This paper reviews the classification,biogenesis,and mechanism of action of tsRNAs,and the research progress to date on tsRNAs in cancers.These findings provide new opportunities for diagnostic biomarkers and treatment targets of several types of cancers including gastric cancer,colorectal cancer,hepatocellular carcinomas,pancreatic cancer,breast cancer,prostate cancer,renal cell carcinoma,ovarian cancer,lung cancer,bladder cancer,thyroid cancer,oral cancer,and leukemia.

关键词： Biomarker Cancer gene expression tRNA tsRNA

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Development of porphyrin-based fluorescent sensors and sensor arrays for saccharide recognition

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Chinese Chemical Letters 2024年第2期35卷 16-23页

作者： Yubin Ding jiaxin Wang Ruinan Wang Yongshu Xie Department of Chemistry College of SciencesNanjing Agricultural UniversityNanjing 210095China Shanghai Key Laboratory of Functional Materials Chemistry Key Laboratory for Advanced Materials and Institute of Fine ChemicalsSchool of Chemistry and Molecular EngineeringEast China University of Science & TechnologyShanghai 200237China

Saccharide sensing is a very meaningful research topic as saccharides are involved in many biological activities.However,it is challenging to design molecular sensors for saccharides because this family of compounds is hydromimetic in aqueous solutions and shares a similar chemical structure.In this review,research progress in the development of porphyrin-based saccharide sensors is described with representative examples.We focus on using porphyrin as the signal reporter because porphyrins exhibit unique advantages in high chemical stability,long emission wavelength,and multiple structural modification strategies.Reported literature results have been classified into mainly two sections according to the general working principles of the porphyrin sensor molecules.In the first section,recognition unit,design strategy and sensing performance of traditional porphyrin-based selective saccharide sensors are discussed.While in the second section,development of porphyrin-based sensor arrays for pattern recognition of saccharides has been summarized.Looking through the design strategy and sensing performance of reported achievements,it is reasonable to anticipate a bright future for designing practical porphyrin-based saccharide sensors.

关键词： Porphyrin Saccharide Fluorescent sensing Selective sensing Pattern recognition

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ROS-responsive hydrogels with spatiotemporally sequential delivery of antibacterial and anti-inflammatory drugs for the repair of MRSA-infected wounds

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Regenerative Biomaterials 2024年第1期3卷 119-131页

作者： Bowen Qiao jiaxin Wang Lipeng Qiao Aziz Maleki Yongping Liang Baolin Guo Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research College of StomatologyXi’an Jiaotong UniversityXi’an 710049China State Key Laboratory for Mechanical Behavior of Materials Frontier Institute of Science and TechnologyXi’an Jiaotong UniversityXi’an 710049China Zanjan Pharmaceutical Nanotechnology Research Center(ZPNRC) Zanjan 45139-56184Iran Department of Orthopaedics The First Affiliated Hospital of Xi’an Jiaotong UniversityXi’an 710061People’s Republic of China

For the treatment of MRSA-infected wounds,the spatiotemporally sequential delivery of antibacterial and anti-inflammatory drugs is a promising strategy.In this study,ROS-responsive HA-PBA/PVA(HPA)hydrogel was prepared by phenylborate ester bond cross-linking between hyaluronic acid-grafted 3-amino phenylboronic acid(HA-PBA)and polyvinyl alcohol(PVA)to achieve spatiotemporally controlled release of two kinds of drug to treat MRSA-infected wound.The hydrophilic antibiotic moxifloxacin(M)was directly loaded in the hydrogel.And hydrophobic curcumin(Cur)with anti-inflammatory function was first mixed with Pluronic F127(PF)to form Cur-encapsulated PF micelles(Cur-PF),and then loaded into the HPA hydrogel.Due to the different hydrophilic and hydrophobic nature of moxifloxacin and Cur and their different existing forms in the HPA hydrogel,the final HPA/M&Cur-PF hydrogel can achieve different spatiotemporally sequential delivery of the two drugs.In addition,the swelling,degradation,self-healing,antibacterial,anti-inflammatory,antioxidant property,and biocompatibility of hydrogels were tested.Finally,in the MRSA-infected mouse skin wound,the hydrogel-treated group showed faster wound closure,less inflammation and more collagen deposition.Immunofluorescence experiments further confirmed that the hydrogel promoted better repair by reducing inflammation(TNF-a)and promoting vascular(VEGF)regeneration.In conclusion,this HPA/M&CurPF hydrogel that can spatiotemporally sequential deliver antibacterial and anti-inflammatory drugs showed great potential for the repair of MRSA-infected skin wounds.

关键词： MRSA-infected wounds spatiotemporally sequential delivery antibacterial anti-inflammatory

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Ultralow friction PTFE/PEEK heterolayer:A new solid lubrication approach toward simplicity

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Friction 2024年第1期12卷 120-135页

作者： Wei SUN jiaxin YE Qingrui SONG Yi FENG Xiaojun LIU School of Materials Science and Engineering Hefei University of TechnologyHefei 230009China Institute of Tribology School of Mechanical EngineeringHefei University of TechnologyHefei 230009China

Tribological applications of polytetrafluoroethylene(PTFE)are often limited by technological complexity to overcome its poor wear resistance.Here,a PTFE/polyetheretherketone(PEEK)heterolayer(HL)was proposed and evaluated as a new solid lubrication solution.Pin-on-disk tribometry found the lowest friction coefficient(μ)of 0.031 and ultralow wear for the PEEK/HL under typical conditions.The friction coefficient of the HL surpasses those of the state-of-the-art polymeric coatings/composites by at least 200%,and approaches that of highly lubricated interfaces.Mechanistic investigations revealed multi-length physical and chemical heterogeneity of the HL that best facilitates a tribofilm with high subsurface stability and surface instability.The technological simplicity and robustness of the HL’s high lubricity make it a promising new type of solid lubrication toward greater reliability and longevity.

关键词： ultralow friction anti-wear polytetrafluoroethylene(PTFE) heterolayer(HL)

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A Piezoelectrically Driven Microrobot Using a Novel Monolithic Spatial Parallel Mechanism as Its Hip Joint

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Journal of Bionic Engineering 2024年第2期21卷 803-820页

作者： Guangping Wu Ziyang Wang jiaxin Zhao Feng Cui Xinghan Cai National Key Laboratory of Advanced Micro and Nano Manufacture Technology Shanghai Jiao Tong UniversityShanghai200240China Department of Micro-Nano Electronics School of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai200240China

Inspired by the fast,agile movements of insects,we present a 1.9 g,4.5 cm in length,piezoelectrically driven,quadrupedal microrobot.This microrobot uses a novel spatial parallel mechanism as its hip joint,which consists of two spatially orthogonal slider-crank linkages.This mechanism maps two inputs of two independent actuators to the decoupled swing and lift outputs of a leg,and each leg can produce the closed trajectories in the sagittal plane necessary for robot motion.Moreover,the kinematics of the transmission are analyzed,and the parameters of the flexure hinges are designed based on geometrical constraints and yield conditions.The hip joints,legs and exoskeletons are integrated into a five-layer standard laminate for monolithic fabrication which is composed of two layers of carbon fiber,two layers of acrylic adhesive and a polyimide film.The measured output force(15.97 mN)of each leg is enough to carry half of the robot’s weight,which is necessary for the robot to move successfully.It has been proven that the robot can successfully perform forward and turning motions.Compared to the microrobot fabricated with discrete components,the monolithically fabricated microrobot is more capable of maintaining the original direction of locomotion when driven by a forward signal and has a greater speed,whose maximum speed is 25.05 cm/s.

关键词： Insect-like Crawling microrobot Piezoelectric drive Parallel mechanism Monolithic fabrication

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Effects of physical crust on soil detachment by overland flow in the Loess Plateau region of China

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International Soil and Water Conservation Research 2024年第1期12卷 107-120页

作者： jiaxin Liu Liding Chen Bing Wang Xiaoyu Peng School of Ecology and Environmental Science Yunnan UniversityKunming650091China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationNorthwest A&F UniversityYanglingShaanxi712100China University of Chinese Academy of Sciences Beijing100049China

Physical soil crust(PSC),a key component of surface soil structure,exists extensively in loess areas.PSC is considered to have a significant effect on soil detachment processes.However,the long-term effects and the corresponding mechanisms of PSC on soil detachment by overland flow are still not well understood,especially in natural environments.To investigate temporal variation in soil erosion resistance and the underlying factors during PSC formation,an 8×8-m soil plot was exposed to natural conditions in the Loess Plateau over a 524-day period spanning two rainy seasons and a winter between them.A flume test was conducted to determine soil detachment capacity(Dc)under six designed flow shear stress levels(5.66-22.11 Pa)using crusted(SC)and non-crusted(NSC)soil samples at different PSC development stages.Subsequently,two soil erosion resistance parameters,rill erodibility(K_(r))and critical shear stress(τ_(c)),were calculated.Over time,in the SC and NSC treatments,K_(r)decreased from 0.516 to 0.120 s m^(-1)and 0.521 to 0.223 s m^(-1),respectively,whileτ_(c)increased from 0.49 to 4.42 Pa and 0.26-2.46 Pa,respectively.Variation in soil erosion resistance was rapid in the first one to two months,and then slowed down,with slight fluctuations afterwards.In the SC treatment,K_(r)was 42%lower andτ_(c)was 67%greater than those in the NSC treatment.Soil properties changed greatly for both treatments.SCT increased from 0 to 7.09 mm in the SC treatment.Coh increased from 2.91 to 9.04 kPa and 3.01-4.78 kPa in SC and NSC treatments,respectively.Both soil erosion resistance parameters could be well predicted by SCT and Coh in the SC treatment(R^(2)≥0.82),while their best predictor was Coh in the NSC treatment(R^(2)≥0.90).The results demonstrate that PSC formation enhances soil erosion resistance in the soil detachment process in the loess region under natural conditions.Our study revealed the important role and complexity of PSC in the process of soil erosion,and provided theoretical and data support for accurate understandi

关键词： Physical soil crust formation Soil heterogeneity Rill erodibility Critical shear stress

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Catalytic degradation of chlorinated volatile organic compounds(CVOCs)over Ce-Mn-Ti composite oxide catalysts

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Journal of Environmental Sciences 2024年第4期138卷 326-338页

作者： Zhiwei Zhou Qianqian Li Guijin Su jiaxin Pang Bohua Sun Jing Meng Bin Shi Henan Institute of Advanced Technology Zhengzhou UniversityZhengzhou 450052China Key Laboratory of Environmental Nanotechnology and Health Effects State Key Laboratory of Environmental Chemistry and EcotoxicologyResearch Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China

Developing industrially moldable catalysts with harmonized redox performance and acidity is of great significance for the efficient disposal of chlorinated volatile organic compounds(CVOCs)in actual exhaust gasses.Here,commercial TiO_(2),typically used for molding catalysts,was chosen as the carrier to fabricate a series of Ce_(0.02)Mn_(0-0.24)TiO_(x) materials with different Mn doping ratios and employed for chlorobenzene(CB)destruction.The introduction of Mn remarkedly facilitated the synergistic effect of each element via the electron transfer processes:Ce^(3+)+Mn^(4+/3+)■Ce^(4+)+Mn^(3+/2+)and Mn^(4+/3+)+Ti^(4+)■Mn^(3+/2+)+Ti^(3+).These synergistic interactions in Ce_(0.02)Mn_(0.04-0.24)TiO_(x),especially Ce_(0.02)Mn_(0.16)TiO_(x),significantly elevated the active oxygen species,oxygen vacancies and redox properties,endowing the superior catalytic oxidation of CB.When the Mn doping amount increased to 0.24,a separate Mn_(3)O_(4) phase appeared,which in turn might weaken the synergistic effect.Furthermore,the acidity of Ce_(0.02)Mn_(0.04-0.24)TiO_(x) was decreased with the Mn doping,regulating the balance of redox property and acidity.Notably,Ce_(0.02)Mn_(0.16)TiO_(x) featured relatively abundant B-acid sites.Its coordinating redox ability and moderate acidity promoted the deep oxidation of CB and RCOOH-intermediates,as well as the rapid desorption of Cl species,thus obtaining sustainable reactivity.In comparison,CeTiO_(x) owned the strongest acidity,however,its poor redox property was not sufficient for the timely oxidative decomposition of the easier adsorbed CB,resulting in its rapid deactivation.This finding provides a promising strategy for the construction of efficient commercial molding catalysts to decompose the industrial-scale CVOCs.

关键词： Chlorobenzene Ce_(0.02)Mn_(0-0.2)4tiox materials Redox ability Acidity Synergistic interaction

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Two material removal modes in chemical mechanical polishing:mechanical plowing vs.chemical bonding

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Friction 2024年第5期12卷 897-905页

作者： Yuan WU Liang JIANG Wenhui LI jiaxin ZHENG Yushan CHEN Linmao QIAN Tribology Research Institute State Key Laboratory of Rail Transit Vehicle SystemSouthwest Jiaotong UniversityChengdu610031China

With the rapid development of semiconductors,the number of materials needed to be polished sharply increases.The material properties vary significantly,posing challenges to chemical mechanical polishing(CMP).Accordingly,the study aimed to classify the material removal mechanism.Based on the CMP and atomic force microscopy results,the six representative metals can be preliminarily classified into two groups,presumably due to different material removal modes.From the tribology perspective,the first group of Cu,Co,and Ni may mainly rely on the mechanical plowing effect.After adding H_(2)O_(2),corrosion can be first enhanced and then suppressed,affecting the surface mechanical strength.Consequently,the material removal rate(MRR)and the surface roughness increase and decrease.By comparison,the second group of Ta,Ru,and Ti may primarily depend on the chemical bonding effect.Adding H_(2)O_(2)can promote oxidation,increasing interfacial chemical bonds.Therefore,the MRR increases,and the surface roughness decreases and levels off.In addition,CMP can be regulated by tuning the synergistic effect of oxidation,complexation,and dissolution for mechanical plowing,while tuning the synergistic effect of oxidation and ionic strength for chemical bonding.The findings provide mechanistic insight into the material removal mechanism in CMP.

关键词： Chemical mechanical polishing corrosion wear material removal mode mechanical plowing chemical bonding

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