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Influence of non-uniform ultrasonic vibration on casting fluidity of liquid aluminum alloy

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China Foundry 2022年第5期19卷 380-386页

作者： Zi-heng Han Zhi-ming Wang Zhi-ping Sun Bing-rong Zhang wei-feng rao School of Mechanical Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China

The application of ultrasonic vibration to the casting process can be realized through mould(die)***,the resonant vibration of the mould is always accompanied by a non-uniform vibration distribution at different parts,which may induce a complex liquid flow and affect the casting fluidity during the mould filling *** influence of non-uniform ultrasonic vibration on the fluidity of liquid AlSi9Cu3 alloy was studied by mould vibration with different vibration *** is found that ultrasonic mould vibration can generate two opposite effects on the casting fluidity:the first,ultrasonic cavitation in melt induced by mould vibration promotes the casting fluidity;the second,the non-uniform mould vibration can induce a melt flow toward the weak vibration areas and turbulence there,consequently decreasing the casting *** the melt flow and turbulence are violent enough to offset the promoting effect of cavitation on fluidity,the ultrasonic vibration will finally induce a resultant decrease of casting *** decreasing effect is proportional to the vibration gradient.

关键词： ultrasonic vibration vibration gradient aluminum alloy fluidity

Nanoembryonic thermoelastic equilibrium and enhanced properties of defected pretransitional materials

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npj Computational Materials 2018年第1期4卷 178-184页

作者： Ye-Chuan Xu wei-feng rao John W.Morris Jr. Armen G.Khachaturyan Department of Materials Physics and IEMMNanjing University of Information Science and TechnologyNanjing 210044China Department of Materials Science and Engineering University of CaliforniaBerkeleyCA 94720USA Department of Materials Science and Engineering Rutgers UniversityPiscatawayNJ 08854USA

Behaviors of displacive phase-transforming materials above the temperature of transformation,where abnormal thermal,elastic,magnetic properties are often observed,are mostly explained by intrinsic peculiarities in electronic/atomic ***,we show these properties may also be attributed to extrinsic effects caused by a thermoelastic equilibrium in highly defected pretransitional *** demonstrate that the stress concentration near stress-generating defects such as dislocations and coherent precipitates could result in the stress-induced transformation within nanoscale regions,producing equilibrium embryos of the product *** nanoembryos in thermoelastic equilibrium could anhysteretically change their equilibrium size in response to changes in applied stress or magnetic fields leading to superelasticity or *** response to cooling may explain the observed diffuse phase transformation,changes in the coefficient of thermal expansion and effective elastic modulus,which,in turn,may explain the invar and elinvar behaviors.

关键词： transformation equilibrium transitional

On the reverse leakage current of Schottky contacts on free-standing GaN at high reverse biases

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Chinese Physics B 2017年第2期26卷 403-405页

作者： Yong Lei Jing Su Hong-Yan Wu Cui-Hong Yang wei-feng rao Department of Materials Physics School of Physics and Optoelectronic Engineering Nanjing University of Information Science and Technology Nanjing 210044 China

In this work, a dislocation-related tunneling leakage current model is developed to explain the temperature-dependent reverse current–voltage（I–V –T） characteristics of a Schottky barrier diode fabricated on free-standing GaN substrate for reverse-bias voltages up to-150 V. The model suggests that the reverse leakage current is dominated by the direct tunneling of electrons from Schottky contact metal into a continuum of states associated with conductive dislocations in GaN epilayer.A reverse leakage current ideality factor, which originates from the scattering effect at metal/GaN interface, is introduced into the model. Good agreement between the experimental data and the simulated I–V curves is obtained.

关键词： homoepitaxial GaN Schottky contact leakage current tunneling dislocations ideality factor

Magnetic properties of L1_0 FePt thin film influenced by recoverable strains stemmed from the polarization of Pb(Mg_(1/3)Nb_(2/3))O_3–PbTiO_3 substrate

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Chinese Physics B 2018年第7期27卷 515-520页

作者： Li-Wang Liu Cheng-Chao Hu Ye-Chuan Xu Hou-Bing Huang Jiang-wei Cao Linyun Liang wei-feng rao Department of Materials Physics and IEMMNanjing University of Information Science and TechnologyNanfing 210044China College of Materials Science and Engineering Liaocheng UniversityLiaocheng 252059China Department of Physics University of Science and Technology BeijingBeijing 100083China Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education Lanzhou UniversityLanzhou 730000China Mathematics and Computer Science Division Argonne National LaboratoryArgonneIllinois 60439USA

The magnetic properties and magnetization reversible processes of Llo FePt （3 nm）/Pb（Mg1/3Nb2/3）O3-PbTiO3 （PMN-PT） heterostructure were investigated by using the phase field model. The simulation results show that the magnetic coercivities and magnetic domains evolution in the Llo FePt thin film are significantly influenced by the compressive strains stemming from the polarization of single crystal PMN-PT substrate under an applied electric field. It is found that the magnetic coercivities increase with increasing of the compressive strain. A large compressive strain is beneficial to aligning the magnetic moments along the out-of-plane direction and to the enhancement of perpendicular magnetic anisotropy. The variations of magnetic energy densities show that when compressive strains are different at the magnetization reversible processes, the magnetic anisotropy energies and the magnetic exchange energies firstly increase and then decrease, the negative demagnetization energy peaks appear at coercivities fields, and the magnetoelastic energies are invariable at large external magnetic field with the energy maximum appearing at coercivities fields. The variations of the magnetoelastic energies bring about the perpendicular magnetic anisotropy so that the magnetoelastic energy is lower at the large external magnetic fields, whereas the appearance of magnetoelastic energy peaks is due to the magnetization-altered direction from the normal direction of the plane of the Llo FePt thin film at coercivities fields.

关键词： FePt strain magnetoelastic energy phase field

Recent progress of vanadium-based alloys for fusion application

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Tungsten 2021年第4期3卷 382-392页

作者： Shao-Ning Jiang Fu-Jie Zhou Gao-wei Zhang Xiao-Ou Yi Chang-Wang Yu Xiu-Jie Wang wei-feng rao School of Mechanical and Automotive Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China Shandong Institute of Mechanical Design and Research Jinan 250353China School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

Low-activation vanadium alloys,with the reference composition of V-4Cr-4Ti have been considered as one of the most promising candidate materials for structural components such as the blanket in future fusion reactors,thanks to their excellent neutron irradiation resistance,superior high-temperature mechanical properties,and high compatibility with liquid lithium *** self-cooled liquid lithium blanket using structural materials of vanadium alloys is an attractive concept because of the high heat transfer and high tritium breeding *** more than 2 decades of research,technological progress has been made in reducing the number of critical issues for application of vanadium alloys to fusion *** this paper,the recent research and development activities of vanadium alloys are summarized,including significant progress achieved on fabrication technology and composition optimization,coating and corrosion,improved understanding of irradiation effects upon microstructure and material properties,retention of hydrogen isotopes,as well as advancements in joining and *** particular,the fact that recent products from China,Japan,US and France showed similar properties which meant the fabrication technology has been almost standardized.

关键词： Vanadium alloy Fabrication Coating and corrosion Irradiation damage Hydrogen retention

Computer simulation of super-magnetoelastic behavior near critical region of magnetic materials based on phase-field method

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Rare Metals 2023年第8期42卷 2477-2488页

作者： Zhao Zhang Cheng-Chao Hu An-Hang Zhou Yu-Xin Xu Yuan-Yuan Wu Hai-Hua Huang Hou-Bing Huang Jun-Jie Ni wei Li wei-feng rao School of Materials Science and Engineering Liaocheng UniversityLiaocheng 252059China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China School of Mechanical Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China Shandong Institute of Mechanical Design and Research Jinan 250031China

Since the discovery of ferromagnetic morphotropic phase boundary(MPB)in 2010,the connotation and extension of MPB have been becoming more and more *** the last dozen years,much experimental work has been done to design magnetostrictive materials based on the MPB ***,due to the difficulty in direct experimental observations and the complexity of theoretical treatments,the insight into the microstructure property relationships and underlying mechanisms near the ferromagnetic MPB has not been fully ***,we have reviewed our recent computer simulation work about the super-magnetoelastic behavior near the critical region of several typical ***-field modeling and simulation are employed to explore the domain configuration and engineering in single crystals as well as the grain size effect in ***,a general nano-embryonic mechanism for superelasticity is also ***,some future perspectives and challenges are presented to stimulate a deeper consideration of the research paradigm between multiscale modeling and material development.

关键词： Super-magnetoelastic behavior Phase-field simulation Morphotropic phase boundary(MPB)

Design and characterization of biodegradable Mg-Zn-Ag metallic glasses

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Transactions of Nonferrous Metals Society of China 2024年第9期34卷 2814-2827页

作者： Jian WANG Chen WANG wei-feng rao In-ho JUNG School of Mechanical Engineering Yangzhou UniversityYangzhou 225009China Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Korea School of Mechanical and Automotive Engineering Qilu University of TechnologyJinan 250353China

In order to develop the Mg-Zn-Ag metallic glasses(MGs)for biodegradable implant applications,the glass formation ability(GFA)and biocompatibility of Mg-Zn-Ag alloys were investigated using a combination of the calculation of phase diagrams(CALPHAD)and experimental *** GFA potentiality of two alloy series,specifically Mg_(96-x)Zn_xAg_(4)and Mg_(94-x)Zn_xAg_6(x=17,20,23,26,29,32,35),was predicted theoretically and then substantiated through experimental testing.X-ray diffraction(XRD)and differential scanning calorimetry(DSC)techniques were used to evaluate the crystallinity,GFA,and crystallization characteristics of these *** results showed that compositions between Mg_(73)Zn_(23)Ag_(4)and Mg_(64)Zn_(32)Ag_(4)for Mg_(96-x)Zn_xAg_4,Mg_(66)Zn_(28)Ag_(6)and Mg_(63)Zn_(31)Ag_(6for)Mg_(94-x)Zn_xAg_(6)displayed a superior ***,the GFA of the Mg_(96-x)Zn_xAg_(4)series was better than that of the Mg_(94-x)Zn_xAg_(6)***,the Mg_(70)Zn_(26)Ag_4,Mg_(74)Zn_(20)Ag_6,and Mg_(71)Zn_(23)Ag_(6)alloys showed acceptable corrosion rates,good cytocompatibility,and positive effects on cell *** characteristics make them suitable for applications in medical settings,potentially materials as biodegradable implants.

关键词： glass forming ability calculation phase diagram(CALPHAD) Mg−Zn−Ag metallic glasses cytocompatibility

Infiltration by monocytes of the central nervous system and its role in multiple sclerosis: reflections on therapeutic strategies

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Neural Regeneration Research 2025年第3期20卷 779-793页

作者： Guangyong Zhang Qing Yao Chubing Long Pengcheng Yi Jiali Song Luojia Wu wei Wan Xiuqin rao Yue Lin Gen wei Jun Ying Fuzhou Hua Department of Anesthesiology the Second Affiliated Hospital of Nanchang UniversityNanchangJiangxi ProvinceChina Key Laboratory of Anesthesiology of Jiangxi Province NanchangJiangxi ProvinceChina

Mononuclear macrophage infiltration in the central nervous system is a prominent feature of neuroinflammation. Recent studies on the pathogenesis and progression of multiple sclerosis have highlighted the multiple roles of mononuclear macrophages in the neuroinflammatory process. Monocytes play a significant role in neuroinflammation, and managing neuroinflammation by manipulating peripheral monocytes stands out as an effective strategy for the treatment of multiple sclerosis, leading to improved patient outcomes. This review outlines the steps involved in the entry of myeloid monocytes into the central nervous system that are targets for effective intervention: the activation of bone marrow hematopoiesis, migration of monocytes in the blood, and penetration of the blood–brain barrier by monocytes. Finally, we summarize the different monocyte subpopulations and their effects on the central nervous system based on phenotypic differences. As activated microglia resemble monocyte-derived macrophages, it is important to accurately identify the role of monocyte-derived macrophages in disease. Depending on the roles played by monocyte-derived macrophages at different stages of the disease, several of these processes can be interrupted to limit neuroinflammation and improve patient prognosis. Here, we discuss possible strategies to target monocytes in neurological diseases, focusing on three key aspects of monocyte infiltration into the central nervous system, to provide new ideas for the treatment of neurodegenerative diseases.

关键词： blood–brain barrier macrophages monocytes multiple sclerosis neuroinflammation review therapy

Passive activity enhances residual control ability in patients with complete spinal cord injury

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Neural Regeneration Research 2025年第8期20卷 2337-2347页

作者： Yanqing Xiao Mingming Gao Zejia He Jia Zheng Hongming Bai Jia-Sheng rao Guiyun Song wei Song Xiaoguang Li Beijing Key Laboratory for Biomaterials and Neural Regeneration Beijing Advanced Innovation Center for Biomedical EngineeringSchool of Biological Science and Medical EngineeringBeihang UniversityBeijingChina Department of Rehabilitation Evaluation China Rehabilitation Research CenterBeijingChina Cardiac Center Beijing Children’s HospitalCapital Medical UniversityBeijingChina The State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijingChina Department of Rehabilitation Engineering China Rehabilitation Science InstituteBeijingChina

Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury ***,because of prolonged inactivity,initial attempts to activate these muscles may not effectively engage any of the remaining neurons in the descending pathway.A previous study unexpectedly found that a brief clinical round of passive activity significantly increased volitional muscle activation,as measured by surface *** this study,we further explored the effect of passive activity on surface electromyographic signals during volitional control tasks among individuals with complete spinal cord *** patients with chronic complete thoracic spinal cord injury were *** electromyography data from eight major leg muscles were acquired and compared before and after the passive activity *** results indicated that the passive activity led to an increased number of activated volitional muscles and an increased frequency of *** the cumulative root mean square of surface electromyography amplitude for volitional control of movement showed a slight increase after passive activity,the difference was not statistically *** findings suggest that brief passive activity may enhance the ability to initiate volitional muscle activity during surface electromyography tasks and underscore the potential of passive activity for improving residual motor control among patients with motor complete spinal cord injury.

关键词： complete spinal cord injury cycle training epidural electrical stimulation motor training passive activity physiological state spinal cord circuit surface electromyography volitional control task