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A simple method to synthesize worm-like AlN nanowires and its field emission studies

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Chinese Physics B 2021年第8期30卷 469-474页

作者： Qi Liang Meng-Qi Yang chang-hao wang Ru-Zhi wang Institute of New Energy Materials and Devices of Faculty of Materials and Manufacturing Key Laboratory of Advanced Functional Materials of Education Ministry of ChinaBeijing University of TechnologyBeijing 100124China

The worm-like AlN nanowires are fabricated by the plasma-enhanced chemical vapor deposition(PECVD)on Si substrates through using Al powder and N2 as precursors,CaF2 as fluxing medium,Au as catalyst,*** as-grown worm-like AlN nanowires each have a polycrystalline and hexagonal wurtzite *** diameters are about 300 nm,and the lengths are over 10μ*** growth mechanism of worm-like AlN nanowires is *** plasma plays a very important role in forming the polycrystalline structure and rough surfaces of worm-like AlN *** worm-like AlN nanowires exhibit an excellent field-emission(FE)property with a low turn-on field of 4.5 V/μm at a current density of 0.01 mA/cm^(2) and low threshold field of 9.9 V/μm at 1 mA/cm^(2).The emission current densities of worm-like AlN nanowires each have a good *** enhanced FE properties of worm-like AlN nanowires may be due to their polycrystalline and rough structure with nanosize and high aspect *** excellent FE properties of worm-like AlN nanowires can be explained by a grain boundary conduction *** results demonstrate that the worm-like AlN nanowires prepared by the proposed simple and the PECVD method possesses the potential applications in photoelectric and field-emission devices.

关键词： worm-like aluminum nitride nanowires growth mechanism plasma enhanced chemical vapor deposition field-emission property

Fabrication and characterization of Al_2O_3-metal composite coating on steel plate with nonpressure combustion synthesis

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Rare Metals 2013年第4期32卷 390-396页

作者： chang-hao wang Ze-Hua wang Ze-Hua Zhou Shao-Qun Jiang Xiao-Feng Xue Jing-Jing Yao College of Mechanics and Materials Hohai University School of Materials Science and Engineering Shanghai University

Al2O3-metal composite coatings with different reactants and diluents were fabricated on mild steel plate with nonpressure combustion synthesis process. The coat-ings were characterized by means of X-ray diffraction, scanning electron microscopy, and energy-dispersive spec-trometry, respectively. Thermal shock tests were carried out to determine the bond strength of the coating with the steel substrate. The results indicate that the coating is composed of α-A1203, α-（Fe-Cr） and Al2SiO5 as the main phases. It is found that the coating with the diluents of Al2O3-SiO2 and transition layer of Al2O3-Cr presents the *** hardness of 2270 HV0.2 and the lowest porosity of 3.93 %. Owing to a metallurgical bond of the coating-to-substrate, the coating exhibits a good thermal shock resistance.

关键词： Combustion synthesis Al2O3-metalcomposite coating Diluents Thermal shock resistance

Bonding characteristics of the Al_2O_3-metal composite coating fabricated onto carbon steel by combustion synthesis

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International Journal of Minerals,Metallurgy and Materials 2014年第9期21卷 886-893页

作者： Xiao-feng Xue Ze-hua wang Ze-hua Zhou Shao-qun Jiang Jiang-bo Cheng chang-hao wang Jia Shao College of Mechanics and Materials Hohai University

The fabrication of an alumina-metal composite coating onto a carbon steel substrate by using a self-propagating high-temperature synthesis technique was demonstrated. The effects of the type and thickness of the pre-coated layer on the binding structure and surface qual- ity of the coating were systematically investigated. The macrostructure, phase composition, and bonding interface between the coating and the substrate were investigated by scanning electronic microscopy （SEM）, X-ray diffraction （XRD）, and energy-dispersive X-ray spectrometry （EDS）. The diffraction patterns indicated that the coating essentially consisted of α-Al2O3, Fe（Cr）, and FeO-Al2O3. With an increase in the thickness of the pre-coated working layer, the coating became more smooth and compact. The transition layer played an important role in enhancing the binding between the coating and the substmte. When the pre-coated working layer was 10 mm and the pre-coated transition layer was 1 ram, a compact structure and metallurgical bonding with the substrate were obtained. Thermal shock test results indicated that the ceramic coating exhibited good thermal shock resistance when the sample was rapidly quenched from 800℃ to room temperature by plunging into water.

关键词： carbon steel combustion synthesis composite coatings phase composition morphology thermal shock resistance

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 ***,the inherent surface roughness and lack of machinability research in AMed HEAs limit their engineering *** 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 *** HEA exhibits similar mechanical properties to SPC HEA due to the pronounced coarsening of L21 *** 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 *** 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 *** 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’***,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

MLDA:a multi-level k-degree anonymity scheme on directed social network graphs

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Frontiers of Computer Science 2024年第2期18卷 199-215页

作者： Yuanjing hao Long LI Liang chang Tianlong GU Guangxi Key Laboratory of Trusted Software Guilin University of Electronic TechnologyGuilin 541004China Engineering Research Center of Trustworthy AI(Ministry of Education) Jinan UniversityGuangzhou 510632China

With the emergence of network-centric data,social network graph publishing is conducive to data analysts to mine the value of social networks,analyze the social behavior of individuals or groups,implement personalized recommendations,and so ***,published social network graphs are often subject to re-identification attacks from adversaries,which results in the leakage of users’***-anonymity technology is widely used in the field of graph publishing,which is quite effective to resist re-identification ***,the current researches still exist some issues to be solved:the protection of directed graphs is less concerned than that of undirected graphs;the protection of graph structure is often ignored while achieving the protection of nodes’identities;the same protection is performed for different users,which doesn’t meet the different privacy requirements of ***,to address the above issues,a multi-level-degree anonymity(MLDA)scheme on directed social network graphs is proposed in this ***,node sets with different importance are divided by the firefly algorithm and constrained connectedness upper approximation,and they are performed different-degree anonymity protection to meet the different privacy requirements of ***,a new graph anonymity method is proposed,which achieves the addition and removal of edges with the help of fake *** addition,to improve the utility of the anonymized graph,a new edge cost criterion is proposed,which is used to select the most appropriate edge to be ***,to protect the community structure of the original graph as much as possible,fake nodes contained in a same community are merged prior to fake nodes contained in different *** results on real datasets show that the newly proposed MLDA scheme is effective to balance the privacy and utility of the anonymized graph.

关键词： directed social network graph graph publishing k-degree anonymity community structure graph utility

Regulation of the quantum barrier and carrier transport toward high-efficiency quasi-2D Dion-Jacobson tin perovskite solar cells

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Journal of Energy Chemistry 2024年第8期95卷 200-207,I0005页

作者： Huanhuan Yao chang Shi Tai Wu Shurong wang Mingyu Yin Liming Ding Yong Hua Feng hao School of Materials and Energy University of Electronic Science and Technology of ChinaChengdu 611731SichuanChina College of Chemistry and Molecular Engineering Peking UniversityBeijing 100871China Yunnan Key Laboratory for Micro/Nano Materials&Technology School of Materials and EnergyYunnan UniversityKunming 650091YunnanChina Center for Excellence in Nanoscience(CAS) Key Laboratory of Nanosystem and Hierarchical Fabrication(CAS)National Center for Nanoscience and TechnologyBeijing 100190China

Quasi-2D Dion-Jacobson(DJ)tin halide perovskite has attracted much attention due to its elimination of Van der Waals gap and enhanced environmental ***,the bulky organic spacers usually form a natural quantum well structure,which brings a large quantum barrier and poor film quality,further limiting the carrier transport and device ***,we designed three organic spacers with different chain lengths(ethylenediamine(EDA),1,3-propanediamine(PDA),and 1,4-butanediamine(BDA))to investigate the quantum barrier *** and experimental characterizations indicate that EDA with short chain can reduce the lattice distortion and dielectric confinement effect,which is beneficial to the effective dissociation of excitons and the inhibition of trap-free non-radiative *** addition,EDA cation shows strong interaction with the inorganic octahedron,realizing large aggregates in precursor solution and high-quality films with improved structural ***,femtosecond transient absorption proves that EDA cations can also weaken the formation of small n-phases with large quantum barrier to achieve effective carrier transport between different ***,the quasi-2D DJ(EDA)FA_(9)Sn_(10)I_(31)solar cells achieves a 7.07%power conversion efficiency with good environment ***,this work sheds light on the regulation of the quantum barrier and carrier transport through the chain length of organic spacer for qua si-2D DJ lead-free perovskites.

关键词： Chain lengths Organic spacers Quantum well Carrier transport Lattice distortion

Simultaneously enhancing erosion and compression resistance:designing AlCoCrFeNi high-entropy alloy strengthened Ag-based contacts

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Rare Metals 2024年第9期43卷 4476-4492页

作者： Xiao-Yang Xue Zhe wang Hui-Ling Nie Zhao Yuan Jun wang chang-Hu Xu Kai Wen Cong-hao Yu School of Materials Science and Engineering Xi’an Polytechnic University School of Physics Xi’an Jiaotong University Key Laboratory of Pulsed Power Technology School of Electrical and Electronic EngineeringHuazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and Technology

Designing microstructures and unveiling dynamic erosion mechanisms remain important challenges for Ag-based contacts. To simultaneously enhance erosion and compression resistance, an Al Co Cr Fe Ni high-entropy alloy(HEA) is introduced into Ag-based materials to fabricate novel Ag-HEA contacts with island-and skeletonrestricted microstructures. The arc erosion experimental results reveal that the skeleton-restricted HEA microstructure is the key factor in reducing the hill and crater morphologies of the contact surface, effectively delaying material transfer between the movable and stationary contacts. The molten bridge evolution and compressive deformation behavior of Ag-HEA contacts with various microstructures are investigated using molecular dynamics(MD) simulations. MD results indicate that the constraint of Ag atom diffusion in the molten pool and the involvement of HEA atoms in the molten bridge are the primary mechanisms for improving erosion resistance. The skeleton-restricted HEA microstructure reduces the total energy and structural stability of the molten bridge system and promotes its fracture and disintegration. Moreover, the synergistic effect of the twin and Lomerz–Cottrell lock structures can hinder dislocation glide, generating dispersed and small-area stacking faults in the Ag matrix and mitigating the concentration of shear strains. Thus, the skeleton-restricted HEA microstructure contributes positively to compression resistance. This study presents a novel approach to designing Ag-based contacts.

关键词： Arc erosion Electrical contact materials High entropy alloys Microstructures Molecular dynamics

Effect of tubastatin A on NLRP3 inflammasome activation in macrophages under hypoxia/ reoxygenation conditions

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World Journal of Emergency Medicine 2024年第4期15卷 289-296页

作者： hao Li chang Liu Ying Cui Panpan chang Wei Chong Department of Emergency Medicine the First Hospital of China Medical UniversityShenyang 110001China Trauma Medicine Center Peking University People's HospitalBeijing 100871China Key Laboratory of Trauma and Neural Regeneration Peking UniversityBeijing 100871China National Center for Trauma Medicine of China Beijing 100871China

BACKGROUND:There are currently no effective drugs to mitigate the ischemia/reperfusion injury caused by fluid resuscitation after hemorrhagic shock(HS).The aim of this study was to explore the potential of the histone deacetylase 6(HDAC6)-specific inhibitor tubastatin A(TubA)to suppress nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)inflammasome activation in macrophages under hypoxia/reoxygenation(H/R)***:The viability of RAW264.7 cells subjected to H/R after treatment with different concentrations of TubA was assessed using a cell-counting kit-8(CCK8)***,2.5μmol/L TubA was used with RAW264.7 cells under H/R ***264.7 cells were divided into three groups,namely the control,H/R,and TubA *** levels of reactive oxygen species(ROS)in the cells were detected using fluorescence *** protein expression of HDAC6,heat shock protein 90(Hsp90),inducible nitric oxide synthase(iNOS),NLRP3,gasdermin-D(GSDMD),Caspase-1,GSDMD-N,and Caspase-1 p20 was detected by western *** levels of interleukin-1β(IL-1β)and IL-18 in the supernatants were detected using enzyme-linked immunosorbent assay(ELISA).RESULTS:HDAC6,Hsp90,and iNOS expression levels were significantly higher(P<0.01)in the H/R group than in the control group,but lower in the TubA group than in the H/R group(P<0.05).When comparing the H/R group to the control group,ROS levels were significantly higher(P<0.01),but significantly reduced in the TubA group(P<0.05).The H/R group had higher NLRP3,GSDMD,Caspase-1,GSDMD-N,and Caspase-1 p20 expression levels than the control group(P<0.05),however,the TubA group had significantly lower expression levels than the H/R group(P<0.05).IL-1βand IL-18 levels in the supernatants were significantly higher in the H/R group compared to the control group(P<0.01),but significantly lower in the TubA group compared to the H/R group(P<0.01).CONCLUSION:TubA inhibited the expression of HDAC6,Hsp90,and iNOS in macrophages

关键词： Hemorrhagic shock Hypoxia/reoxygenation Macrophage NLRP3 Tubastatin A

Intermittent Theta Burst Stimulation Attenuates Cognitive Deficits and Alzheimer’s Disease-Type Pathologies via ISCA1-Mediated Mitochondrial Modulation in APP/PS1 Mice

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Neuroscience Bulletin 2024年第2期40卷 182-200页

作者： Yang Zhu hao Huang Zhi Chen Yong Tao Ling-Yi Liao Shi-hao Gao Yan-Jiang wang chang-Yue Gao Department of Rehabilitation Medicine Daping HospitalArmy Medical UniversityChongqing 400042China Department of Neurology and Center for Clinical Neuroscience Daping HospitalArmy Medical UniversityChongqing 400042China Department of Special Medicine Daping HospitalArmy Medical UniversityChongqing 400042China

Intermittent theta burst stimulation(iTBS),a time-saving and cost-effective repetitive transcranial magnetic stimulation regime,has been shown to improve cognition in patients with Alzheimer’s disease(AD).However,the specific mechanism underlying iTBS-induced cognitive enhancement remains *** studies suggested that mitochondrial functions are modulated by magnetic ***,we showed that iTBS upregulates the expression of iron-sulfur cluster assembly 1(ISCA1,an essential regulatory factor for mitochondrial respiration)in the brain of APP/PS1 *** vivo and in vitro studies revealed that iTBS modulates mitochondrial iron-sulfur cluster assembly to facilitate mitochondrial respiration and function,which is required for ***,iTBS rescues cognitive decline and attenuates AD-type pathologies in APP/PS1 *** present study uncovers a novel mechanism by which iTBS modulates mitochondrial respiration and function via ISCA1-mediated iron-sulfur cluster assembly to alleviate cognitive impairments and pathologies in *** provide the mechanistic target of iTBS that warrants its therapeutic potential for AD patients.

关键词： Intermittent theta burst stimulation Alzheimer’s disease Iron-sulfur cluster assembly 1 Mitochondrial dysfunction Neurodegeneration