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Ab initio STUDIES ON MAGNETISM OF 3d TRANSITION METAL DIMERS

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Acta Metallurgica Sinica(English Letters) 2007年第5期20卷 341-346页

作者： j.H. Gu z.L. zhu School of Physical Engineering and Material Physics Laboratory Zhengzhou University Zhengzhou 450052 China

Ab initio calculations with the self-consistent full-potential linearized augmented-plane-wave method （FLAPW）, under generalized gradient approximation, have been carried out to describe the electronic and magnetic properties of 3d transition metal dimers. It predicted the antiferromagneticity of Cr2 and ferromagneticity of other species. The Mn2 dimer was shown to be ferromagnetic coupling with a local magnetic moment of 5μB. retaining the value of its free atom state. The V2 and Ni2 exhibited low spin-polarization with local magnetic moment of only 1μB per atom. On the other hand, Fe2 and Co2 were highly spin-polarized with local magnetic moments of 3 and 2μB.

关键词： magnetism 3d transition metal dimer ab initio calculation

Surface Characterisation of Silicon Based MEMS

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Chemical Research in Chinese Universities 2004年第4期20卷 407-410页

作者： LI j. CUI z M. A. Baker The Surface Analysis Laboratory School of Engineering University of SurreyRutherford Appleton LaboratoryThe Surface Analysis Laboratory School of Engineering University of Surrey Guildford GU2 7XH UKChilton Didcot UKGuildford GU2 7XH UK

Polysilicon Microelectromechanical systems(MEMS) are the subject of intensive researches. Surface chemistry and topography of a MEMS test structure fabricated at Sandia National Laboratory, USA, were studied by means of scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS) and atomic force microscopy(AFM). XPS C_ 1sand Si_ 2pspectra from the polysilicon components, silicon nitride substrate and a reference silicon wafer were compared. The results confirm the presence of a self-assembled monolayer(SAM) on the MEMS surface. An island-like morphology was found on both polysilicon and silicon nitride surfaces of the MEMS. The islands take the form of caps, being up to 0.5 μm in diameter and 20 nm in height. It is concluded that the co-existence of columnar growth and equiaxed growth during the low pressure chemical vapor deposition(LPCVD) of these layers leads to the observed morphology and the islands are caps to the columnar structures.

关键词： Microelectromechanical systems XPS Atomic force microscopy

Design and optimization of the composition and mechanical properties for non-equiatomic CoCrNi medium-entropy alloys

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journal of Materials Science & Technology 2023年第8期139卷 232-244页

作者： j.X.Yan z.j.zhang P.zhang j.H.Liu H.Yu Q.M.Hu j.B.Yang z.F.zhang Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Chongqing Jiaotong UniversityChongqing 400074China chool of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China School of Information Science and Engineering Shenyang University of TechnologyShenyang 111003China

The development of multi-principal element alloys(MPEAs,also called as high-or medium-entropy al-loys,HEAs/MEAs)provides tremendous possibilities for materials ***,designing MPEAs with desirable mechanical properties confronts great challenges due to their vast composition *** this work,we provide an essential criterion to efficiently screen the CoCrNi MEAs with outstanding strength-ductility *** negative Gibbs free energy difference△E_(FCC-BCC)between the face-centered cubic(FCC)and body-centered cubic(BCC)phases,the enhancement of shear modulus G and the decline of stacking fault energy(SFE)γ_(isf)are combined as three requisites to improve the FCC phase stability,yield strength,deformation mechanisms,work-hardening ability and ductility in the *** effects of chemical composition on△E_(FCC-BCC),G andγisf were investigated with the first principles calculations for Co_(x)Cr_(33)Ni_(67-x),Co_(33)Cr_(y)Ni_(67-y)and Co_(z)Cr_(66-z)Ni_(34)(0≤x,y≤67 and 0≤z≤66)*** on the essential criterion and the calculation results,the composition space that displays the neg-ative Gibbs free energy difference△E_(FCC-BCC),highest shear modulus G and lowest SFEγ_(isf)was screened with the target on the combination of high strength and excellent *** this context,the optimal composition space of Co-Cr-Ni alloys was predicted as 60 at.%-67 at.%Co,30 at.%-35 at.%Cr and 0 at.%-6 at.%Ni,which coincides well with the previous experimental evidence for Co_(55)Cr_(40)Ni_(5)*** valid-ity of essential criterion is further proved after systematic comparison with numerous experimental data,which demonstrates that the essential criterion can provide significant guidance for the quick exploitation of strong and ductile MEAs and promote the development and application of MPEAs.

关键词： Medium-entropy alloys First-principles calculations Phase stability Stacking-fault energy Strength Ductility

HIGH-TEMPERATURE TENSILE FRACTURE BEHAVIOR OF DIRECTIONALLY SOLIDIFIED Ni,Cr,Al-TaC EUTECTIC SUPERALLOY

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 455-459页

作者： j.zhang j.j.Yu H.z.Fu State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi'an 710072ChinaInstitute of Metal Research Chinese Academy of Sciences Shenyang 110016 ChinaState Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi'an 710072China

The high-temperature tensile fracture behavior of the Ni, Cr, Al-TaC eutectic superal-loy directionally solidified under high temperature gradient is investigated. The high-temperature tensile fracture of this in situ composite has ductile character with lots of ductile nests whose diameters decrease with the increasing solidification rates. The maximum σb and δ are respectively 668.5MPa and 19.6%. There is α TaC whisker in the center of each nest, and the deformation of γ' and TaC is uneven. The high-temperature tensile behavior cannot be explained by the rule of mixtures but is decided by the formation of the plastic deformation band. The crack extension model is given.

关键词： Ni Cr Al-TaC eutectic superalloy directional solidification,in situ composite high-temperature tenslie fracture

Shape Memory Effect,Thermal Expansion and Damping Property of Friction Stir Processed NiTip/Al Composite

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journal of Materials Science & Technology 2016年第2期32卷 162-166页

作者： D.R.Ni j.j.Wang z.Y.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang I10016China College of Material Science and Engineering ShenyangAerospace University Shenyang 110136China

NiTi particles reinforced aluminum （NiTip/Al） composite was prepared via friction stir processing, elimi- nating interfacial reaction and/or elemental diffusion. The NiTip in the composite maintained the intrinsic characteristic of a reversible thermoelastic phase transformation even after heat-treatment. The shape memory characteristic of the NiTip decreased the coefficient of thermal expansion of the Al matrix, and an apparent two-way shape memory effect was observed in the composite. The composite owned a good combination of adjustable damping and thermal physical properties.

关键词： Metal matrix composite Shape memory alloy Interface Differential scanning calorimetry (DSC)Damping

Ibuprofen-Induced Toxic Epidermal Necrolysis:A Case Report

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International journal of Dermatology and Venereology 2024年第2期7卷 108-110页

作者： Nevin Kannappilly Mohamed z.Peediyakkal Mohamad Y.Khatib Dore C.Ananthegowda Moustafa S.Elshafei Hani El zeer Karimulla S.Shaik Moayad M.AlFayoumi Dyaneshwar P.Mutkule Ahmed A.Soliman Abdulqadir j.Nashwan Critical Care Department Hamad Medical Corporation(HMC)Doha 3050Qatar

Introduction:Toxic epidermal necrolysis(TEN)is a medical emergency that most commonly occurs as an adverse effect of certain ***,we describe a case of a 41-year-old man with no comorbid illness who developed *** presentation:The patient had been prescribed ibuprofen for myalgia and developed skin lesions after the single *** lesions were erythematous papules and macules distributed all over the body after ibuprofen *** was diagnosed based on the patient’s clinical presentation and laboratory *** was treated with intravenous dexamethasone,intravenous immunoglobulin,and *** dressing changes and skin care was done with saline,chlorhexidine,and liquid *** patient was intubated and tracheostomized,and he gradually improved and ***,he developed septicemia in the intensive care unit and was treated ***:The management of TEN includes cessation of the causative cause,multidisciplinary intensive care unit(ICU)care,prevention and early detection of sepsis,fluid and electrolyte balance,adequate analgesia and temperature control,proper organ support,aggressive nutritional management,and good psychological *** pharmacological therapy for TEN includes corticosteroids,intravenous immunoglobulin,and *** key elements of management are aseptic care and proper dressing of the ***:TEN is associated with high mortality if not managed in a systemic and protocolized way.

关键词： ibuprofen toxic epidermal necrolysis erythema drug-induced erythema

Diameter distributions in Pinus sylvestris ***:evaluating modelling approaches including a machine learning technique

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林业研究:英文版 2023年第6期34卷 1829-1842页

作者： Şükrü Teoman Güner Maria j.Diamantopoulou Ramazan Özçelik Department of Forestry Ulus Vocational SchoolBartın University74600 UlusBartınTurkey Faculty of Agriculture Forestry and Natural EnvironmentSchool of Forestry and Natural EnvironmentAristotle University of Thessaloniki54124 ThessalonikiGreece Faculty of Forestry Isparta University of Applied ScienceEast Campus32260 IspartaTurkey

The diameter distribution of trees in a stand provides the basis for determining the stand’s ecological and economic value,its structure and stability and appropriate management *** pine(Pinus sylvestris L.)is one of the most common and important conifers in Turkey,so a well-planned management schedule is *** distribution models to accurately describe the stand structure help improve management strategies,but developing reliable models requires a deep understanding of the growth,output and constraints of the *** most important information derived by diameter distribution models is primary data on horizontal stand structure for each diameter class of trees:basal area and volume per unit *** predictions are required to estimate the range of products and predicted volume and yield from a forest ***,to construct an accurate,reliable diameter distribution model for natural Scots pine stands in the Türkmen Mountain region,we used johnson’s SBdistribution to represent the empirical diameter distributions of the stands using ground-based measurements from 55 sample plots that included1219 trees in natural distribution zones of the *** an alternative,nonparametric approach,which does not require any predefined function,an artificial intelligence model was constructed based on support vector machine *** error index was calculated to evaluate the ***,both johnson’s SB probability density function with a three-parameter recovery approach and the support vector regression methodology provided reliable estimates of the diameter distribution of these stands.

关键词： Diameter distribution johnson’s S_(B) Support vector regression Scots pine Türkmen mountains

Surface deformation-dependent mechanical properties of bending nanowires:an ab initio core-shell model

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Applied Mathematics and Mechanics(English Edition) 2022年第2期43卷 219-232页

作者： Ye XIAO j.SHANG L.z.KOU Chun LI School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710072China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical UniversityXi’an710072China School of Mechanical Medical and Process EngineeringQueensland University of TechnologyBrisbaneQLD4000Australia

An ab initio core-shell model is proposed to evaluate the surface effect in bending nanowires,in which the elastic modulus depends on the surface relaxation and deformation induced by external *** using first-principles calculations based on the density functional theory(DFT),the surface and bulk properties are calculated for Ag,Pb,and Si *** obtained theoretical predictions of the effective Young’s modulus of nanowires agree well with the experimental data,which shows that the fixed-fixed nanowire is stiffened and the cantilevered nanowire is softened as the characteristic size of the cross section ***,the contrastive analysis on the two kinds of nanowires demonstrates that increasing the nanowire aspect ratio would enhance the surface *** present results could be helpful for understanding the size effect in nanowires and designing nanobeam-based devices in nanoelectromechanical systems(NEMSs).

关键词： surface effect density functional theory(DFT) surface relaxation surface stress nanowire

Formation of TiAlSi intermetallics during heating Ti-A356 Al mixed powder compact at semisolid temperature

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journal of Materials Science & Technology 2021年第35期94卷 247-263页

作者： M.Gao T.j.Chen z.X.zhang State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of TechnologyLanzhou 730050China

Due to the similarity in composition and crystal structure of some Ti Al Si ternary intermetallics,it is quite difficult to accurately confirm their physic characteristics,and thus,to tailor microstructure to improve mechanical properties of metal materials related to the Ti Al Si ***,the formation process of Ti Al Si intermetallics was investigated during heating Ti-A356 mixed powder compact at a A356 alloy semisolid temperature of 595℃.The results indicated that two kinds of intermetallics ofτ1(tetragonal,I41/amd)andτ2(orthorhombic,Cmcm)generated,and both the concentration and supply direction of Ti atoms,which are related to local breakage of oxide films on neighboring Ti and A356 alloy powders,determined the phase and morphology of the intermetallics.τ1 andτ2 crystals all had an intrinsic plate morphology,butτ2 crystals were thinner due to more anisotropic growth resulted from their high density of stacking faults(SFs).τ1 lamellar domains generated during growth ofτ2 crystals,which were accompanied by decrease in density of *** combined effect of size difference and internal energy difference betweenτ1 andτ2 crystals made largeτ1 crystals coarsen at the expense ofτ2 crystals in Ostwald ripening,leading them to finally evolve into an agglomerate of largeτ1 plates.

关键词： Intermetallics Stacking faults Growth Phase transformation