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Abnormal mechanochemical effect in ultraprecision machining of an additively manufactured precipitation-strengthened high-entropy alloy

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Journal of Materials Science & Technology 2024年第3期170卷 221-237页

作者： Long xu Yuchao bai Yunfa Guo Chang Ren Xiaohua Tan Yandong Jia Gang Wang Hao Wang Institute of Materials Shanghai UniversityShanghai 200444China Zhejiang Institute of Advanced Materials Shanghai UniversityJiashan 314100China Department of Mechanical Engineering National University of SingaporeSingapore 117575Singapore

Recently,researchers have explored the use of precipitation strengthening and finer microstructures with high-density dislocations in additive manufacturing to produce high-entropy alloys(HEAs)with adjustable properties.However,the inherent surface roughness and lack of machinability research in AMed HEAs limit their engineering applications.In this study,we systematically investigated the microstructural characteristics,mechanical properties,and machinability of Fe_(29.3)Co_(28.7)Ni_(28.6)Al_(6.8)Ti_(6.6)(at.%)HEAs with three different structures:single FCC phase cellular(SPC),dual precipitation-strengthened(DPS),and single precipitation-strengthened(SPS).These structures were fabricated by selective laser melting and isothermally annealing at 780 and 940℃.Compared to SPC HEA,DPS HEA exhibits a significant increase in yield strength and ultimate tensile strength but with a dramatic sacrifice in ductility.SPS HEA exhibits similar mechanical properties to SPC HEA due to the pronounced coarsening of L21 precipitates.The ultraprecision machining micro-cutting test showed that SPC HEA had a significant mechanochem-ical effect,as evidenced by a sharp drop in cutting force for inked workpieces,but not DPS HEA.An abnormal finding was that the negligible reflection of cutting force for SPS HEAs suggested a negative mechanochemical effect,even though SPS HEA had equally excellent plasticity like SPC HEA.It was found that nanocrystallization-induced strength enhancement and ductility reduction of SPS HEA lead to chips’deformation dominated by shear avalanche rather than chip folding of SPC HEA,which involves the reduction of surface energy and friction of chips’interfaces.Overall,these results and our research findings may guide the machining of AMed precipitation-strengthened HEAs and accelerate their engineering ap-plication.

关键词： High-entropy alloy Selective laser melting Precipitation strengthening Machinability Mechanochemical effect

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miR-125b reverses cisplatin resistance by regulating autophagy via targeting RORA/BNIP3L axis in lung adenocarcinoma

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Oncology Research 2024年第4期32卷 643-658页

作者： LEI LIU NA GUO XIANGLING LI QIAN xu RUILONG HE LIMIN CHENG CHUNYAN DANG XINYU bai YIYING bai XIN WANG QIANHUI CHEN LI ZHANG Department of Immunology Chengde Medical UniversityChengde067000China Department of Pathology Chengde Medical UniversityChengde067000China Department of Oncology The Affiliated Hospital of Chengde Medical UniversityChengde067000China Department of Hepatobiliary Surgery The Affiliated Hospital of Chengde Medical UniversityChengde067000China

The platinum-based chemotherapy is one of the most frequently used treatment protocols for lung adenocarcinoma(LUAD),and chemoresistance,however,usually results in treatment failure and limits its application in the clinic.It has been shown that microRNAs(miRNAs)play a significant role in tumor chemoresistance.In this study,miR-125b was identified as a specific cisplatin(DDP)-resistant gene in LUAD,as indicated by the bioinformatics analysis and the real-time quantitative PCR assay.The decreased serum level of miR-125b in LUAD patients was correlated with the poor treatment response rate and short survival time.MiR-125b decreased the A549/DDP proliferation,and the multiple drug resistance-and autophagy-related protein expression levels,which were all reversed by the inhibition of miR-125b.In addition,xenografts of human tumors in nude mice were suppressed by miR-125b,demonstrating that through autophagy regulation,miR-125b could reverse the DDP resistance in LUAD cells,both in vitro and in vivo.Further mechanistic studies indicated that miR-125b directly repressed the expression levels of RORA and its downstream BNIP3L,which in turn inhibited autophagy and reversed chemoresistance.Based on these findings,miR-125b in combination with DDP might be an effective treatment option to overcome DDP resistance in LUAD.

关键词： Lung adenocarcinoma miRNAs Cisplatin Resistance Autophagy

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Dual-additives enable stable electrode-electrolyte interfaces for long life Li-SPAN batteries

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Chinese Chemical Letters 2024年第5期35卷 459-465页

作者： Zhenqiang Guo Huicong Yang Qian Wei Shengjun xu Guangjian Hu Shuo bai Feng Li School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Department of Biochemistry and Molecular Biology College of Life ScienceChina Medical UniversityShenyang 110122China Dalian National Laboratory for Clean Energy Dalian 116023China Shenyang King Power Technology Co. Ltd.Shenyang 110016China

Sulfurized polyacrylonitrile(SPAN)is proposed as a promising cathode material for lithium sulfur batteries.However,the continuous side reactions at the electrolyte-electrode interfaces as well as the slow redox kinetics of SPAN cathode deteriorate the electrochemical performance.In this study,an electrolyte with dual-additives comprising 2-fluoropyridine(2-FP)and lithium difluorobis(oxalato)phosphate(LiDFBOP)was used to improve the performance of Li||SPAN cells.2-FP has a lower lowest occupied molecular orbital energy than that of the solvents in the electrolyte,leading to its prior reduction.A LiF-rich film can be formed on the electrode,effectively improving the stability of the electrolyte-electrode interfaces and prolonging the life.Simultaneously,LiDFBOP could form an electrolyte-electrode interface film containing a large amount of Li_(x)PO_(y)F_(z) species,compensating for the kinetic deterioration caused by the lower ionic conductive of LiF formed at the electrolyte-electrode interface.Hence,an electrode-interface film with good chemical stability and high Li^(+) transport was established by LiF and Li_(x)PO_(y)F_(z)-rich species.The Li||SPAN cell with the electrolyte containing dual-additives demonstrates an excellent capacity retention of 97.5%after 200 cycles at 1.0 C,25℃,comparing to 56.2%capacity retention without additives.Moreover,the rate capacities of cells with dual-additives can reach 1128.1 mAh/g at 5 C,comparing to only 813.5 mAh/g using electrolyte without additives.Our results shown that the dual-additives in electrolyte provide a promising strategy for practical application of lithium sulfur batteries with SPAN cathodes.

关键词： Sulfurized polyacrylonitrile Lithium metal Interface film 2-Fluoropyridine Difluorobis(oxalato)phosphate

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Random Exponential Attractor for Stochastic Non-autonomous Suspension Bridge Equation with Linear Multiplicative White Noise

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Journal of Mathematical Research with Applications 2024年第1期44卷 81-112页

作者： Ling xu Runjie LIU xue bai College of Mathematics and Statistics Northwest Normal University

In this paper, we mainly consider the long-time behavior of stochastic non-autonomous suspension bridge equation by linear multiplicative white noise with small coefficient. First step,the well-posedness for the cocycle associated with the considered system is established. Second step, the existence of random attractor for the system is investigated. Third step, the upper semicontinuity of random attractor is also provided when the coefficient of random term approaches zero. Fourth step, we prove the regularity of random attractor in a higher regular space by the“iteration” method. Finally, we give the existence of a random exponential attractor for the considered system, which implies the finiteness of fractal dimension of random attractor.

关键词： stochastic non-autonomous suspension bridge equation multiplicative white noise random attractor fractal dimension random exponential attractor

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Effects of Fe solid solute on grain boundaries of bi-crystal Cu: A molecular dynamics simulation

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Nano Materials Science 2024年第1期6卷 86-95页

作者： Shuohan Yang Hongwei Bao Huizhong bai Yan Li Haodong xu Fei Ma State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an710049ShaanxiChina

Grain boundaries(GBs)play a crucial role on the structural stability and mechanical properties of Cu and its alloys.In this work,molecular dynamics(MD)simulations are employed to study the effects of Fe solutes on the formation energy,excess volume,dislocations and melting behaviors of GBs in CuFe alloys.It is illustrated that Fe solute affects the structural stability of Cu GBs substantially,the formation energy of GBs is reduced,but the thickness and melting point of GBs are increased,that is,the structural stability of Cu GBs is significantly improved owing to the Fe solutes.A strong scaling law exists between the formation energy,excess volume,thickness and melting point of GBs.Therefore,Fe solid solute plays an important role in the characteristics of GBs in bi-crystal Cu.

关键词： CuFe alloy Grain boundary Structural stability MD simulations

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A Review on Engineering Transition Metal Compound Catalysts to Accelerate the Redox Kinetics of Sulfur Cathodes for Lithium–Sulfur Batteries

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Nano-Micro Letters 2024年第5期16卷 300-332页

作者： Liping Chen Guiqiang Cao Yong Li Guannan Zu Ruixian Duan Yang bai Kaiyu xue Yonghong Fu Yunhua xu Juan Wang Xifei Li Shaanxi Key Laboratory of Nanomaterials and Nanotechnology Xi’an University of Architecture and TechnologyXi’an 710055People’s Republic of China Institute of Advanced Electrochemical Energy and School of Materials Science and Engineering Xi’an University of TechnologyXi’an 710048People’s Republic of China Yulin University Yulin 719000People’s Republic of China School of Materials Science and Engineering Fuzhou UniversityFuzhou 350108People’s Republic of China

Engineering transition metal compounds(TMCs)catalysts with excellent adsorption-catalytic ability has been one of the most effec-tive strategies to accelerate the redox kinetics of sulfur cathodes.Herein,this review focuses on engineering TMCs catalysts by cation doping/anion doping/dual doping,bimetallic/bi-anionic TMCs,and TMCs-based heterostructure composites.It is obvious that introducing cations/anions to TMCs or constructing heterostructure can boost adsorption-catalytic capacity by regulating the electronic structure including energy band,d/p-band center,electron filling,and valence state.Moreover,the elec-tronic structure of doped/dual-ionic TMCs are adjusted by inducing ions with different electronegativity,electron filling,and ion radius,resulting in electron redistribution,bonds reconstruction,induced vacancies due to the electronic interaction and changed crystal structure such as lat-tice spacing and lattice distortion.Different from the aforementioned two strategies,heterostructures are constructed by two types of TMCs with different Fermi energy levels,which causes built-in electric field and electrons transfer through the interface,and induces electron redistribution and arranged local atoms to regulate the electronic structure.Additionally,the lacking studies of the three strategies to comprehensively regulate electronic structure for improving catalytic performance are pointed out.It is believed that this review can guide the design of advanced TMCs catalysts for boosting redox of lithium sulfur batteries.

关键词： Lithium–sulfur battery Redox kinetic Transition metal compounds catalyst Multiple metals/anions

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Impact of inter-turn short fault on winding insulation temperature rising characteristic in PMSG

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Dianji yu Kongzhi xuebao/Electric Machines and Control 2024年第4期28卷 18-30页

作者： He, Yuling Li, Yong Zhang, Wen bai, Yifan xu, Mingxing Wang, Xiaolong Department of Mechanical Engineering Hebei Engineering Research Center for Advanced Manufacturing & Intelligent Operation and Maintenance of Electric Power Machinery North China Electric Power University Baoding 071003 China

The winding insulation temperature rising characteristic was investigated before and after interturn short circuit (ITSC) in permanent magnet synchronous generators (PMSG). Firstly, the magnetic flux density, stator current, core loss and copper loss expressions in normal and ITSC conditions were deduced. Then three dimensional finite element analysis (FEA) models were established. The varied types of loss were calculated in the electromagnetic filed and imported into the temperature field to obtain the temperature distribution of winding insulation. Finally, the experiments were taken on the LR -5 prototype PMSG to measure the winding insulation temperature. The experiment results are good accorded with the theoretical analysis and FEA results. It is shown that the winding temperature will increase significantly acted by the shorted winding current under ITSC fault. The server ITSC fault degree is intensified, the higher winding insulation temperature will be. In addition, the deformation, strain and stress resulting from the uneven distribution of thermal load on the winding insulation will also intensify. The insulation at the nose end of the winding is prone to damage due to high temperatures. This can be addressed by improving the cooling and heat dissipation structure or applying a heat-resistant coating to enhance the reliability of the insulation at the nose end. © 2024 Editorial Department of Electric Machines and Control. All rights reserved.

关键词： Permanent magnets

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Diabetes mellitus in patients with type 1 autoimmune pancreatitis at diagnosis and after corticosteroid therapy

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Hepatobiliary & Pancreatic Diseases International 2024年第4期23卷 393-398页

作者： Mei-Zi Li Tao Guo Yun-Lu Feng Sheng-Yu Zhang Xiao-Yin bai Xi Wu Kai xu Ai-Ming Yang Department of Gastroenterology State Key Laboratory of Complex Severe and Rare DiseasesPeking Union Medical College HospitalPeking Union Medical College and Chinese Academy of Medical SciencesBeijing 100730China Department of Radiology Peking Union Medical College HospitalPeking Union Medical College and Chinese Academy of Medical SciencesBeijing 100730China

Background:A high prevalence of diabetes mellitus(DM)coexisting with autoimmune pancreatitis(AIP)is observed.However,evidence on the circumstances under which corticosteroid therapy(CST)for AIP improves or worsens DM is scarce.This study aimed to demonstrate and identify predictors of DM control under the influence of CST.Methods:Patients diagnosed with type 1 AIP were enrolled from a prospectively maintained cohort and were classified into three groups according to the chronology in which AIP and DM were diagnosed:pre-existing DM(pDM),concurrent DM(cDM),and non-DM(nDM).The responses of DM to CST were assessed when corticosteroid was ceased or tapered to a maintenance dose and classified as‘improvement’and‘non-improvement’(including‘no change’and‘exacerbation’).Results:Among 101 patients with type 1 AIP,52(51.5%)patients were complicated with DM at the time of AIP diagnosis,with 36 patients in the cDM group and 16 patients in the pDM group.The incidences of diffuse pancreatic swelling(72.2%)and pancreatic body/tail involvement(91.7%)were significantly higher in the cDM group than in both the pDM and nDM groups.Of the 52 patients with DM,CST was administered in 48 cases.Multivariate logistic analysis identified that elevated serum gamma-glutamyl transferase(GGT)level at AIP diagnosis[odds ratio(OR)=0.032,95%confidence interval(CI):0.003-0.412,P=0.008]and pancreatic atrophy after CST(OR=0.027,95%CI:0.003-0.295,P=0.003)were negatively associated with DM control improvement.Conclusions:Patients with diffuse pancreatic swelling and pancreatic body/tail involvement in pancreatitis tended to be complicated with cDM at AIP diagnosis.CST exerted a beneficial effect on the clinical course of DM in nearly half of the AIP patients complicated with DM at diagnosis,particularly in those without elevated serum GGT levels at diagnosis and who did not experience pancreatic atrophy after CST.

关键词： Type 1 autoimmune pancreatitis Diabetes mellitus Corticosteroid therapy Predictive factor Pancreatic atrophy

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Clinical efficacy and pathological outcomes of transanal endoscopic intersphincteric resection for low rectal cancer

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World Journal of Gastrointestinal Oncology 2024年第3期16卷 933-944页

作者： Zhi-Wen xu Jing-Tao Zhu Hao-Yu bai xue-Jun Yu Qing-Qi Hong Jun You Department of Gastrointestinal Oncology Surgery The First Affiliated Hospital of Xiamen UniversitySchool of MedicineXiamen UniversityXiamen 361000Fujian ProvinceChina

BACKGROUND Transanal endoscopic intersphincteric resection(ISR)surgery currently lacks sufficient clinical research and reporting.AIM To investigate the clinical effectiveness of transanal endoscopic ISR,in order to promote the clinical application and development of this technique.METHODS This study utilized a retrospective case series design.Clinical and pathological data of patients with lower rectal cancer who underwent transanal endoscopic ISR at the First Affiliated Hospital of Xiamen University between May 2018 and May 2023 were included.All patients underwent transanal endoscopic ISR as the surgical approach.We conducted this study to determine the perioperative recovery status,postoperative complications,and pathological specimen charac-teristics of this group of patients.RESULTS This study included 45 eligible patients,with no perioperative mortalities.The overall incidence of early complications was 22.22%,with a rate of 4.44%for Clavien-Dindo grade≥III events.Two patients(4.4%)developed anastomotic leakage after surgery,including one case of grade A and one case of grade B.Postoperative pathological examination confirmed negative circumferential resection margins and distal resection margins in all patients.The mean distance between the tumor lower margin and distal resection margin was found to be 2.30±0.62 cm.The transanal endoscopic ISR procedure consistently yielded high quality pathological specimens.CONCLUSION Transanal endoscopic ISR is safe,feasible,and provides a clear anatomical view.It is associated with a low incidence of postoperative complications and favorable pathological outcomes,making it worth further research and application.

关键词： Intersphincteric resection Transanal Rectal cancer Complications Endoscopic

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Instrumented oscillographic study on impact toughness of an axle steel DZ2 with different tempering temperatures

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1590-1598页

作者： Shuo Liu Peng Zhang Bin Wang Kaizhong Wang Zikuan xu Fangzhong Hu Xin bai Qiqiang Duan Zhefeng Zhang Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Technology Center Ma'anshan Iron and Steel Co.Ltd.Ma'anshan 243000China

Compared with the conventional Charpy impact test method,the oscillographic impact test can help in the behavioral analysis of materials during the fracture process.In this study,the trade-off relationship between the strength and toughness of a DZ2 axle steel at various tempering temperatures and the cause of the improvement in impact toughness was evaluated.The tempering process dramatically influenced carbide precipitation behavior,which resulted in different aspect ratios of carbides.Impact toughness improved along with the rise in tempering temperature mainly due to the increase in energy required in impact crack propagation.The characteristics of the impact crack propagation process were studied through a comprehensive analysis of stress distribution,oscilloscopic impact statistics,fracture morphology,and carbide morphology.The poor impact toughness of low-tempering-temperature specimens was attributed to the increased number of stress concentration points caused by carbide morphology in the small plastic zone during the propagation process,which resulted in a mixed distribution of brittle and ductile fractures on the fracture surface.

关键词： axle steel DZ2 tempering process impact toughness oscillographic impact test impact crack propagation carbides

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