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Effect of vacuum heat treatment on microstructure and corrosion behavior of HVOF sprayed AICoCrFeNiCu high entropy alloy

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Journal of Iron and Steel Research International 2023年第8期30卷 1550-1561页

作者： Yong-kuan Zhou l Jia-jie Kang guo Jin Xiu-fang Cui Jie Zhang guo-zheng ma Zhi-qiang Fu Li-na Zhu Ding-shun She Yu-yun Yang School of Engineering and Technology China University of Geosciences(Beijing)Beijing 100083China School of materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212100JiangsuChina zhengzhou Institute China University of Geosciences(Beijing)Zhengzhou 451283HenanChina College of material Science and Chemical Engineering Harbin Engineering UniversityHarbin 150001HeilongjiangChina Department of Mechanical Engineering Imperial College LondonLondon SW72AZUK National Key Lab for Remanufacturing Academy of Armored Forces EngineeringBeijing 100072China

To improve the corrosion resistance of coalbed methane drilling equipment,an AICoCrFeNiCu high entropy alloy coating was prepared on the AISI 4135(35CrMo)steel substrate by high velocity oxygen fuel(HVOF)technology,and the coating was subjected to vacuum heat treatment(VHT)at different temperatures(500,700,900 and 1100℃).The corrosion test of the substrate and the coatings after VHT in coalbed methane drilling fluid was carried *** results show that the HVOF sprayed AICoCrFeNiCu high entropy alloy(HEA)coating has a good bonding with the substrate,and the porosity of the coating is about 2.4%.There is partial segregation in the coating,and the coating mainly consists of body-centered cubic *** coating has good thermal stability,and the phase structure and microstructure of the coatings have changed after VHT at different *** with the substrate,the as-sprayed coating has better uniform corrosion resistance,and the corrosion resistance of the coating after VHT is further *** VHT at 500℃,the HVOF-sprayed AICoCrFeNiCu HEA coating has the best corrosion resistance.

关键词： High velocity oxygen fuel AICoCrFeNiCu high entropy alloy coating Vacuum heat treatment Microstructure Corrosion

Influence of in-flight particle characteristics and substrate temperature on the formation mechanisms of hypereutectic Al-Si-Cu coatings prepared by supersonic atmospheric plasma spraying

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Journal of materials Science & Technology 2021年第28期87卷 216-233页

作者： Peng-fei He guo-zheng ma Hai-dou Wang Ling Tang Ming Liu Yu Bai Yu Wang Jian-jiang Tang Dong-yu He Hai-chao Zhao Tian-yang Yu National Key Laboratory for Remanufacturing Army Academy of Armored ForcesBeijing 100072China School of Mechanical Engineering and Automation Beihang UniversityBeijing100191China State Key Laboratory for Mechanical Behavior of materials Xi’an Jiaotong UniversityXi’an710049China State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityXi’an710049China School of materials Engineering Xi'an Aeronautical UniversityXi'an710077China

Hypereutectic Al-Si-Cu coatings were prepared by supersonic atmospheric plasma spraying to enhance the surface performance of lightweight *** find out optimum process conditions and achieve desirable coatings,this work focuses on the influence of three important parameters(in-flight particle temperature,impact velocity,and substrate temperature)on the collected splats morphology coatings microstructure and *** show that appropriate combinations of temperature and velocity of in-flight particles cannot only completely melt hypereutectic Al-Si-Cu particles especially the primary Si phase,but also provide the particles with sufficient kinetic ***,the optimized coating consists of 98.6%of fully-melted region with nanosized coupled eutectic and 0.9%of *** the substrate deposition temperature promotes the transition from inhomogeneous banded microstructure to homogeneous equiaxed microstructure with a lower porosity *** observations are further interpreted by a newly developed phase-change heat transfer model on quantitatively revealing the solidification and remelting behaviors of several splats deposited on substrate Besides,phase evolutions including the formation of supersaturatedα-Al matrix solid solution,growth of Si and Al_(2)Cu phases at different process conditions are *** ideal microstructure(low fractions of unmelted/partially-melted regions and defects)together with solid solution,grain refinement and second phase strengthening effects contributes to the enhanced microhardness of *** integrated study not only provides a framework for optimizing Al-Si based coatings via thermal spraying but also gives valuable insights into the formation mechanisms of this class of coating materials.

关键词： Thermal sprayed coatings Al-Si alloys In-flight particle characteristics Substrate temperature Process control

Effect of cholesterol metabolism on hepatolithiasis

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World Journal of Gastroenterology 2025年第1期31卷 157-162页

作者： Lin zheng Zi-Yu Ye Jun-Ji ma Department of Gastroenterology The Second Hospital of Hebei Medical UniversityHebei Key Laboratory of GastroenterologyHebei Institute of GastroenterologyHebei Clinical Research Center for Digestive DiseasesNo.215 Heping West RoadShijiazhuang 050000Hebei ProvinceChina

Surgical intervention is currently the primary treatment for hepatolithiasis;how-ever,some patients still experience residual stones and high recurrence rates after *** metabolism seems to play an important role in hepatoli-thiasis pathogenesis.A high cholesterol diet is one of the significant reasons for the increasing incidence of ***,regular diet and appropriate medical intervention are crucial measures to prevent hepatolithiasis and reduce recurrence rate after *** dietary cholesterol and drugs that increase cholesterol stone solubility are key therapeutic approaches in treating *** article discusses the cholesterol metabolic pathways related to the pathogenesis of hepatolithiasis,as well as food intake and targeted therapeutic drugs.

关键词： Hepatolithiasis Cholesterol metabolism High-fat diet 3-hydroxy-3-methylglutaryl-coenzyme A reductase Interlobular bile duct

Bandgap characteristics analysis and graded design of a novel metamaterial for flexural wave suppression

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Applied mathematics and Mechanics(English Edition) 2025年第1期46卷 1-24页

作者： Fan YANG Zhaoyang ma Xingming guo Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering ScienceShanghai University Shanghai Institute of Aircraft Mechanics and Control

A novel elastic metamaterial is proposed with the aim of achieving lowfrequency broad bandgaps and bandgap regulation. The band structure of the proposed metamaterial is calculated based on the Floquet-Bloch theorem, and the boundary modes of each bandgap are analyzed to understand the effects of each component of the unit cell on the bandgap formation. It is found that the metamaterials with a low elastic modulus of ligaments can generate flexural wave bandgaps below 300 Hz. Multi-frequency vibrations can be suppressed through the selective manipulation of bandgaps. The dual-graded design of metamaterials that can significantly improve the bandgap width is proposed based on parametric studies. A new way that can regulate the bandgap is revealed by studying the graded elastic modulus in the substrate. The results demonstrate that the nonlinear gradient of the elastic modulus in the substrate offers better bandgap performance. Based on these analyses, the proposed elastic metamaterials can pave the way for multi-frequency vibration control, low-frequency bandgap broadening, and bandgap tuning.

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Synergistic effect of bonding heterogeneity and phonon localization in introducing excellent thermoelectric properties in layered heteroanionic NdZnSbO material

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Journal of Energy Chemistry 2025年第1期100卷 259-272页

作者： Da Wan Shuwei Tang Shulin Bai Xiaodong Li Peng Ai Wanrong guo Tuo zheng College of materials Science and Engineering Liaoning Technical University Faculty of Chemistry Northeast Normal University

Layered rare-earth metal oxides, harnessing the dual properties of oxides and two-dimensional layered materials, exhibit remarkable thermal stability and quantum confinement effects. Therefore, this work adopts the first-principles calculation combined with the Boltzmann transport theory to predict the thermoelectric properties of NdZnSbO compound. The coexistence of weak interlayer van der Waals interactions, robust intralayer ionic bonding, and partial covalent bonding leads to remarkable bonding heterogeneity, which engenders pronounced phonon scattering and imposes constraints on thermal transport along the out-of-plane direction. The weakened chemical bonds induced by the antibonding states, together with the rattling-like behavior of the Zn atom, culminate in the profound anharmonicity in the layered NdZnSbO compound. The weakening bond and heavy element contribute to the softness of phonon modes, which significantly diminishes the phonon group velocity. The redistribution-dominated four-phonon scattering process spans a large optical gap, which effectively reduces the lattice thermal conductivity. The NdZnSbO compound exhibits direct semiconductor characteristic with a bandgap of 0.73 e V by adopting the Heyd-Scuseria-Ernzerhof(HSE06) functional in combination with spin–orbit coupling(SOC) effect. The multi-valley feature of NdZnSbO compound augur favorably for band degeneracy, thus amplifying the power factor. Consequently, an optimal figure-of-merit(ZT) of 3.40 at 900 K is achieved for the n-type NdZnSbO compound. The present study delves deeply insights into the origins for the low thermal conductivity of NdZnSbO compound and proposes an optimization scheme to enhance overall thermoelectric performance.

关键词： Bond strength (chemical)

Near-perfect replication on amorphous alloys through active force modulation based on machine learning/neural network parameter prediction

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 181-191页

作者： Senkuan Meng zheng Wang Ruisong Zhu Ruijie Liu Jiang ma Lina Hu Weihua Wang Key Laboratory for Liquid-Solid Structural Evolution and Processing of materials (Ministry of Education) School of Materials Science and Engineering Shandong University College of Mechatronics and Control Engineering Shenzhen University Songshan Lake materials Laboratory Institute of Physics Chinese Academy of Sciences

As a microforming technique, micro/nano-structural replication possesses advantages of high precision and efficiency. With the remarkable superplasticity in the supercooled liquid region, amorphous alloys or metallic glasses(MGs) are regarded as ideal materials for miniature fabrication. However, due to the intrinsic metastable nature of supercooled liquids, the design of imprinting processes for MGs poses a challenge. In the past, process parameters have largely relied on trial-and-error *** this work, a low-frequency active force modulation system is employed to apply a stable, precise, and real-time feedback stress field for imprinting of MG samples. Low-frequency vibrations can facilitate the filling of microstructures on the template surface by reducing the effective viscosity of the supercooled liquid. With the dataset composed of orthogonal experiments, a machine learning strategy based on back-propagation(BP) neural networks was utilized to construct a 3D parameter space for temperature, stress, and time, and to predict the corresponding filling ratio. Furthermore, the optimal combination of imprinting process parameters was identified, and its filling ratio was experimentally validated to reach as high as 0.94. The near-perfect replication of microstructures confirms the superiority of the active force modulation system and the data-driven strategy of machine learning-assisted parameter design. At the same time, this one-step microforming process provides a new approach to addressing the accuracy-cost trade-off dilemma in precision manufacturing.

关键词： metallic glass amorphous alloy microforming imprinting machine learning

Exosomes:the next-generation therapeutic platform for ischemic stroke

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Neural Regeneration Research 2025年第5期20卷 1221-1235页

作者： Wenjing Yin Hongyin ma Yang Qu Jiaxin Ren Yingying Sun Zhen-Ni guo Yi Yang Stroke Center Department of NeurologyFirst Hospital of Jilin UniversityChangchunJilin ProvinceChina Neuroscience Research Center Department of NeurologyFirst Hospital of Jilin UniversityChangchunJilin ProvinceChina

Current therapeutic strategies for ischemic stroke fall short of the desired objective of neurological functional ***,there is an urgent need to develop new methods for the treatment of this *** are natural cell-derived vesicles that mediate signal transduction between cells under physiological and pathological *** have low immunogenicity,good stability,high delivery efficiency,and the ability to cross the blood–brain *** physiological properties of exosomes have the potential to lead to new breakthroughs in the treatment of ischemic *** rapid development of nanotechnology has advanced the application of engineered exosomes,which can effectively improve targeting ability,enhance therapeutic efficacy,and minimize the dosages *** in technology have also driven clinical translational research on *** this review,we describe the therapeutic effects of exosomes and their positive roles in current treatment strategies for ischemic stroke,including their antiinflammation,anti-apoptosis,autophagy-regulation,angiogenesis,neurogenesis,and glial scar formation reduction ***,it is worth noting that,despite their significant therapeutic potential,there remains a dearth of standardized characterization methods and efficient isolation techniques capable of producing highly purified *** optimization strategies should prioritize the exploration of suitable isolation techniques and the establishment of unified workflows to effectively harness exosomes for diagnostic or therapeutic applications in ischemic ***,our review aims to summarize our understanding of exosome-based treatment prospects in ischemic stroke and foster innovative ideas for the development of exosome-based therapies.

关键词： blood–brain barrier electroacupuncture engineering exercise exosomes ischemic stroke mesenchymal stem cells microglia neuroprotection stents

Constructing Donor–Acceptor‑Linked COFs Electrolytes to Regulate Electron Density and Accelerate the Li^(+)Migration in Quasi‑Solid‑State Battery

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Nano-Micro Letters 2025年第1期17卷 456-471页

作者： Genfu Zhao Hang ma Conghui Zhang Yongxin Yang Shuyuan Yu Haiye Zhu Yongjiang Sun Hong guo School of materials and Energy International Joint Research Center for Advanced Energy Materials of Yunnan ProvinceYunnan UniversityKunming 650091People’s Republic of China Yunnan Yuntianhua Co. LtdR&D CenterKunming 650228People’s Republic of China Southwest United Graduate School Kunming 650091People’s Republic of China

Regulation the electronic density of solid-state electrolyte by donor–acceptor(D–A)system can achieve highly-selective Li^(+)transportation and conduction in solid-state Li metal *** study reports a high-performance solid-state electrolyte thorough D–A-linked covalent organic frameworks(COFs)based on intramolecular charge transfer *** other reported COFbased solid-state electrolyte,the developed concept with D–A-linked COFs not only achieves electronic modulation to promote highly-selective Li^(+)migration and inhibit Li dendrite,but also offers a crucial opportunity to understand the role of electronic density in solid-state Li metal *** introduced strong electronegativity F-based ligand in COF electrolyte results in highlyselective Li^(+)(transference number 0.83),high ionic conductivity(6.7×10^(-4)S cm^(−1)),excellent cyclic ability(1000 h)in Li metal symmetric cell and high-capacity retention in Li/LiFePO_(4)cell(90.8%for 300 cycles at 5C)than substituted C-and N-based *** is ascribed to outstanding D–A interaction between donor porphyrin and acceptor F atoms,which effectively expedites electron transferring from porphyrin to F-based ligand and enhances Li^(+)***,we anticipate that this work creates insight into the strategy for accelerating Li^(+)conduction in high-performance solid-state Li metal batteries through D–A system.

关键词： Electronic modulation engineering Donor-acceptor-linked covalent organic frameworks Quasi-solid-state Li metal battery

紫杉醇合成代谢途径中紫杉烯合成酶cDNA的克隆

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生物工程学报 2000年第2期16卷 158-160页

作者：胡国武温廷益元英进天津大学化工学院天然产物研究所天津300072 天津市中医学院第一附属医院

紫杉烯合成酶(Taxadienesynthase)被认为在紫杉醇合成代谢途径中起着限速酶的作用。为进一步研究紫杉烯合成酶的作用机理和紫杉醇生物合成代谢调控机制,采用RTPCR技术从东北红豆杉(Taxuscuspidata)愈伤组织中获得了紫杉烯合成酶基因片段... 详细信息

紫杉烯合成酶(Taxadienesynthase)被认为在紫杉醇合成代谢途径中起着限速酶的作用。为进一步研究紫杉烯合成酶的作用机理和紫杉醇生物合成代谢调控机制,采用RTPCR技术从东北红豆杉(Taxuscuspidata)愈伤组织中获得了紫杉烯合成酶基因片段,将该片段克隆在载体pGEMTEasyVector上,并转化到大肠杆菌JM109中,经EcoRI酶切检测,Southernblotting及部分cDNA序列分析证实该片段确为紫杉烯合成酶基因,与国外报道的从太平洋红豆杉(***)幼茎中得到的紫杉烯合成酶基因序列具有很高的同源性。

关键词：紫杉醇紫杉烯合成酶 cDNA克隆