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Dislocation self-interaction in TiAl:Evolution of super-dislocation dipoles revealed by atomistic simulations

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Journal of Materials science & Technology 2021年第10期69卷 138-147页

作者： Z.Zhen h.Wang c.Y.Teng c.G.Bai D.s.Xu R.Yang Institute of Metal Research Chinese Academy of SciencesShenyang 110016China school of Materials science and Engineering University of Science and Technology of China.Shenyang 110016China school of Materials science and Engineering University of Shanghai for Science and TechnologyShanghai 200093China Laboratory of Fundamental Research AVIC China Aero-Polytechnology EstablishmentBeijing 100028.China

As one of the fundamental outcomes of dislocation self-interaction,dislocation dipoles have an important influence on the plastic deformation of materials,especially on fatigue and *** this work,superdislocation dipoles inγ-TiAl andα_(2)-Ti_(3)Al were systematically investigated by atomistic simulations,with a variety of dipole heights,orientations and annealing tempe *** results indicate that non-screw super-dipoles transform into locally stable dipolar or reconstructed cores at low temperature,while into isolated or interconnected point defect clusters and stacking fault tetrahedra at high temperature via short-range diffu ***-screw super-dipoles inγ-TiAl andα_(2)-Ti_(3)Al exhibit similar features as fcc and hcp metals,***,over long-term annealing where diffusion is significant,60°superdipoles inγ-TiAl are stable,whereas the stability of super-dipoles inα2-Ti3 Al increases with dipole height and orientation *** influence on mechanical properties can be well evaluated by integrating these results into mesoscale or constitutive models.

关键词： TiAl Dislocation Dipole Mechanical property Atomistic simulation

Effect of radiative loss mechanisms on FIR thermometric parameters of Nd^(3+)-doped lithium tellurite glasses

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Journal of Rare Earths 2024年第7期42卷 1250-1257,I0002页

作者： c.Y.Morassuti A.P.L silva L.A.O.Nunes s.M.Lima L.h.c.Andrade Optical and Photothermal spectroscopy Group(GEOF) Center for Studies in Natural Resources(CERNA)State University of Mato Grosso do Sul(UEMS)C.P.351DouradosMSBrazil Renato Archer Information Technology center Dom Pedro I Highway(SP-65)Km 1436-Chácaras Campos dos AmaraisCampinasSPBrazil Institute of Physics of são carlos University of São PauloSão CarlosSPBrazil

Nd^(3+)-doped tellurite glasses are promising materials for thermometers based on the fluorescence intensity ratio(FIR)***,at high Nd^(3+)concentrations,energy transfer(ET)processes such as optical reabsorption and cross-relaxation can affect the Nd^(3+)emission,which has been little explored in the ***,the present work investigated the use of Nd^(3+)-doped tellurite glass(samples doped with Nd^(3+)at 0.2 mol%,0.5 mol%,2.0 mol%,and 4.0 mol%)in fluorescence thermometers,in the temperature range from 299 to 371 *** results indicate a strong dependence of the FIR parameters on the Nd^(3+)concentration,due to changes in the emission band profiles caused by optical reabsorption of the Nd^(3+)emissions and cross-relaxation processes.A decrease of the relative sensitivity of the ratio^(4)F_(5/2)→^(4)I_(9/2)/^(4)F_(3/2)→^(4)I_(9/2)is observed for samples doped with higher amounts of Nd^(3+).The maximum relative sensitivity at 299 K is 3.00%/K,which is the highest value among the reported Nd^(3+)ions.

关键词： Nd^(3+)-doped tellurite glass Fluorescence intensity ratio Optical thermometry Judd-Ofelt Rare earths

Formation of TiN Grid on NiTi by Laser Gas Nitriding for Improving Wear Resistance in hanks' solution

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Journal of Materials science & Technology 2016年第5期32卷 459-464页

作者： c.h.Ng O.K.chan h.c.Man Department of Industrial and systems Engineering The Hong Kong Polytechnic University

Laser gas nitriding （LGN） is a common surface modification method to enhance the wear resistance of titanium （Ti） alloys, which are known to have poor tribological properties. In the present study, a titanium nitride （TIN） grid network was fabricated on the surface of nickel titanium （NiTi） by LGN. The laser processing parameters were selected to achieve nitriding without surface melting and hence to＇maintain a smooth surface finish. The characteristics of the grid-nitrided samples were investigated by scanningelectron microscopy, X-ray diffractometry, optical microscopy, 2-D profilometry, contact angle measurements and nanoindentation. The wear resistance of the nitrided samples was evaluated using reciprocating wear test against ultra-high-molecular-weight polyethylene （UhMWPE） in hanks＇ solution. The results indicate that the wear rates of the grid-nitrided samples and the UhMWPE counter-body in the wear pair are both significantly reduced. The decrease in wear rates can be attributed to the combination of a hard TiN grid and a soft NiTi substrate. In hanks＇ solution, the higher hydrophilicity of the nitrided samples also contributes to the better performance in wear test against hydrophobic UhMWPE.

关键词： Laser Nitriding surface patterning Titanium alloys Wear

Piezoelectric polarization and quantum size effects on the vertical transport in AlGaN/GaN resonant tunneling diodes

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chinese Physics B 2016年第6期25卷 483-488页

作者： Dakhlaoui h Almansour s Department of Physics College of Science for GirlsUniversity of Dammam (UOD)

In this work,the electronic properties of resonant tunneling diodes（RTDs） based on GaN-AlxGa（1-x）N double barriers are investigated by using the non-equilibrium Green functions formalism（NEG）.These materials each present a wide conduction band discontinuity and a strong internal piezoelectric field,which greatly affect the electronic transport *** electronic density,the transmission coefficient,and the current–voltage characteristics are computed with considering the spontaneous and piezoelectric *** influence of the quantum size on the transmission coefficient is analyzed by varying GaN quantum well thickness,AlxGa1-xN width,and the aluminum concentration *** results show that the transmission coefficient more strongly depends on the thickness of the quantum well than the barrier;it exhibits a series of resonant peaks and valleys as the quantum well width *** addition,it is found that the negative differential resistance（NDR） in the current–voltage（I–V） characteristic strongly depends on aluminum concentration *** is shown that the peak-to-valley ratio（PVR） increases with xAlvalue *** findings open the door for developing vertical transport nitrides-based IsB devices such as Thz lasers and detectors.

关键词： nitride semiconductor resonant tunneling diode current density

current status of the KsTAR Engineering

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Plasma science and Technology 2004年第1期6卷 2159-2165页

作者： J.s.Bak K.Kim c.h.choi Y.K.Oh B.c.Kim N.I.her h.L.Yang G.s.Lee the KsTAR Team Korea Basic science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 Korea

As there is substantial progress in the KsTAR tokamak engineering, all themajor structures and sub-systems are under fabrication and in procurement phase. The vacuum vessel,port, cryostat cylinder, lid, and bellows are being rigorously fabricated in the factory. The lowerpart of the KsTAR such as cryostat base and gravity support has been almost finished in itsfabrication. There are also great progresses and significant results in manufacturing of thesuperconducting magnet, including four Toroidal Field (TF) coils, lower and upper PF7 coils whichare the largest Poloidal Field (PF) coils. The TFOO coil, which has been made for test and back-upof the TF magnet system, was successfully tested in the cool-down and current charging. As thefabrications and procurements of major structures have been actively proceeded, assembly works werealso launched from Aug. 2003. More detailed description on these status, results, and plans will bedescribed in this paper.

关键词： KsTAR tokamak vacuum vessel magnet cryostat tokamak assembly

cr-induced fusion reactions to synthesize superheavy elements

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Nuclear science and Techniques 2024年第5期35卷 122-130页

作者： s.Madhu h.c.Manjunatha N.sowmya B.M.Rajesh L.seenappa R.s.susheela Department of Physics R V College of EngineeringBangalore 560074India Visvesvaraya Technological University BelagaviKarnataka 590018India Department of Physics Government First Grade CollegeSrinivasapurKarnataka 563135India Department of Physics Government First Grade CollegeDevanahallyKarnataka 562110India Department of Physics Government First Grade CollegeMulbagalKarnataka 563131India Department of Physics Government First Grade collegeNanjangudOoty RoadMysore 571301India

We investigated ^(50,52-54)cr-induced fusion reactions for the synthesis of the superheavy element in the 104≤Z≤122 *** cross sections produced in this investigation using ^(54)cr projectiles were compared with those obtained in prior *** estimated cross sections from this analysis are consistent with the findings of prior *** the current study,the predicted cross section was found to be 42fb at 236 MeV for ^(53)cr+^(243)Am,23.2 fb at 236 MeV for ^(54)cr+^(247)cm,95.6 fb at 240 MeV for ^(53)cr+248Bk,and 1.33 fb at 242 MeV for ^(53)cr+***,these projected cross sections with excitation energy and beam energy will be useful in future cr-induced fusion reaction investigations.

关键词： Fusion cross sections compound nucleus formation probability survival probability Evaporation residue cross sections

Amino Acid sequence of an Excitatory Insect-selective Toxin (BmK IT) From Venom of the scorpion Buthus martensi Karsch

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science china chemistry 1994年第1期37卷 42-49页

作者：吉永华 P. Mansuelle 徐科 c. Granier c. Kopeyan s. Terakawa h. Rochat shanghai Institute of Physiology Academia Sinica Shanghai 200031 PRC Laboratoire de Biochemie cNRs URA 1455 INsERM U 172 Faculte de Medcecine secteur Nord BdPierre Dramard 13326 Marseille Cedex 15France

The insect-selective neurotoxin(BmK IT) of scorpion Buthus martensi Karsch was first reduced and s-alkylated, and then digested by TPcK-trypsin and staphylococcus aureus V-8 Protease. The enzymatic peptides were purified on TLc-plastic sheet and submitted to determine their amino acid compositions and sequences. The sequence of the 70 amino acid residues of BmK IT was established with reference to the primary structure of Aah IT, another excitatory insect-selective toxin from the venom of North African scorpion Androctonus australis hector. About 75% of the homologous sequence was found in the molecules of BmK IT and Aah IT. It is obvious that the results contribute toward better understanding of the molecular structure characteristics, structure/activity relationship of scorpion insect-selective toxins, and they can serve as the molecular basis for utilizing the toxins as a tool to clarify molecular mechanism involved in channel gating, and to infer the possibility of developing them as new selective bioinsecticides.

关键词： scorpion Buthus martensi Karsch insect-selective neurotoxin amino acid sequence structure/activity relationship.

EFFEcT OF cARBON AND BORON ON MIcROsTRUcTURE AND MEchANIcAL PROPERTIEs OF A sINGLE cRYsTAL sUPERALLOY RR 2072

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Acta Metallurgica sinica(English Letters) 2005年第1期18卷 33-38页

作者： D.h.Kim D.h.Ye J.h.Lee Y.s.Yoo c.Y.Jo high Temperature Materials Laboratory Korea Institute of Machinery&Materials 66 SangnamChangwonKyungnam 640-010S.Korea Dept.of Metallurgy changwon National Univerisity 9 SarimChagwonKyungnam 640-773S.Korea

carbon and boron have been considered to strengthen grain boundaries that might form during single crystal *** this study the effect of boron on solidification behavior and creep properties of the carbon doped single crystal RR 2072 has been *** order to understand solidification behavior with boron addition,the solid/liquid interface morphology and solidification microstructure were examined with solidification *** relationship between mi-crostructural evolution and creep properties of the carbon and boron modified single crystal has been also investigated.

关键词： single crystal superalloy defect tolerance directional solidification creep rupture

Momentum equation for straight electrically charged jet

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Applied Mathematics and Mechanics(English Edition) 2011年第12期32卷 1515-1524页

作者：张若京 s. h. hOU c. K. chAN school of Aerospace Engineering and Applied Mechanics Tongji University Shanghai 200092 P. R. China Department of Applied Mathematics The Hong Kong Polytechnic University Hong Kong P. R. China

A one-dimensional momentum conservation equation for a straight jet driven by an electrical field is developed. It is presented in terms of a stress component, which can be applied to any constitutive relation of fluids. The only assumption is that the fluid is incompressible. The results indicate that both the axial and radial constitutive relations are required to close the governing equations of the straight charged jet. however, when the trace of the extra stress tensor is zero, only the axial constitutive relation is required. It is also found that the second normal stress difference for the charged jet is always zero. The comparison with other developed momentum equations is made.

关键词： electrically charged jet stability electrospinning