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Effect of Y content and equal channel angular pressing on the microstructure, texture and mechanical property of extruded Mg-Y alloys

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Journal of Magnesium and Alloys 2022年第1期10卷 210-224页

作者： W.Yang g.F.Quan B.Ji Y.F.Wan h.Zhou J.Zheng D.D.yin Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengduSichuan 610031China Nano and heterogeneous Materials Center School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China International Joint Laboratory for Light Alloys(Ministry of Education) College of Materials Science and EngineeringShenyang National Laboratory for Materials ScienceChongqing UniversityChongqing 400044China

The microstructure, texture and mechanical property evolution of the extruded Mg-x Y(x = 1, 5 wt.%) alloys during equal channel angular pressing(ECAP) were systematically investigated using an optical microscope, electron backscatter diffraction(EBSD) and uniaxial tensile test. The Mg-Y alloys exhibited a weakened basal texture before the ECAP, and the texture was further weakened with the max basal poles dispersed along ~45° between the extrusion direction and the transverse direction after the ECAP. The Mg-5 Y alloys always exhibited a finer grain size comparing to that of Mg-1 Y for the same ECAP process. With a proper ECAP process, both the strength and elongation of Mg-5 Y alloy could be improved simultaneously after the ECAP, i.e., the yield strength(273.9 ± 1.2 MPa), ultimate strength(306.4 ± 3.0 MPa),and elongation(23.9 ± 1.0%) were increased by 10%, 6%, and 72%, respectively, comparing to that before the ECAP. This was considered to be arose from the combined effects of grain refinement, significant improved microstructure homogeneity and solid solution *** addition, it was found that Mg-Y alloy with better comprehensive properties could be obtained by the decreasing-temperature ECAP processes. The yield strength-grain size relationship could be well described by the hall-Petch relation for all the ECAPed Mg-Y alloys,which was consistent with that the texture changes did not significantly affect the average Schmid factors of basal, prismatic and pyramidal slips for both Mg-Y alloys.

关键词： Mg-RE alloy Equal channel angular pressing Texture Mechanical property

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Shell-model representations of the microscopic version of the Bohr-Mottelson collective model

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Communications in Theoretical Physics 2024年第8期76卷 79-90页

作者： h g ganev Joint Institute for Nuclear Research DubnaRussia Institute of Mechanics Bulgarian Academy of SciencesSofiaBulgaria

The structure of the irreducible collective spaces of the group Sp(12,R),which many-particle nuclear states are classified according to the chain Sp(12,R)⊃U(6)⊃SO(6)⊃SU_(pn)(3)⊗SO(2)⊃SO(3)of the proton-neutron symplectic model(PNSM),is considered in *** chain of the PNSM was recently shown to correspond to a microscopic shell-model version of the Bohr-Mottelson collective *** construction of the relevant shell-model representations of the Sp(12,R)group along this chain is considered for three nuclei with varying collective properties and from different mass *** is shown that the SU_(pn)(3)basis states of the Sp(12,R)representations belonging to the SO(6)irreps with seniorityυ≥υ0,withυ0 denoting the maximal seniority SO(6)irrep contained in the Sp(12,R)bandhead,are always Pauli allowed,but organized in a different way into different SO(6)*** is in contrast to the case of filling the levels of the standard three-dimensional harmonic oscillator and using the plethysm *** the SU_(pn)(3)multiplets withinυhe present work are important for the practical application of the microscopic version of the Bohr-Mottelson collective model.

关键词： microscopic shell-model version of the Bohr-Mottelson model proton-neutron symplectic model Sp(12,R)dynamical algebra shell-model representations

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Pulse chirping effect on controlling the transverse cavity oscillations in nonlinear bubble regime

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Chinese Physics B 2017年第2期26卷 313-319页

作者： h Vosoughian Z Riazi h Afarideh g Sarri Laser and Optic Institute Nuclear Science and Technology Research Institute Tehran Iran physics and Accelerator School Nuclear Science and Technology Research Institute Tehran Iran Department of Energy Engineering and Physics Amirkabir University of Technology P. O. Box 15875-4413 Tehran Iran School of Mathematics and Physics The Queen's University of Belfast BT7 INN Belfast United Kingdom

The propagation of an intense laser pulse in an under-dense plasma induces a plasma wake that is suitable for the acceleration of electrons to relativistic energies. For an ultra-intense laser pulse which has a longitudinal size shorter than the plasma wavelength, λp, instead of a periodic plasma wave, a cavity free from cold plasma electrons, called a bubble, is formed behind the laser pulse. An intense charge separation electric field inside the moving bubble can capture the electrons at the base of the bubble and accelerate them with a narrow energy spread. In the nonlinear bubble regime, due to localized depletion at the front of the pulse during its propagation through the plasma, the phase shift between carrier waves and pulse envelope plays an important role in plasma response. The carrier–envelope phase（CEP） breaks down the symmetric transverse ponderomotive force of the laser pulse that makes the bubble structure unstable. Our studies using a series of two-dimensional（2D） particle-in-cell（PIC） simulations show that the frequency-chirped laser pulses are more effective in controlling the pulse depletion rate and consequently the effect of the CEP in the bubble regime. The results indicate that the utilization of a positively chirped laser pulse leads to an increase in rate of erosion of the leading edge of the pulse that rapidly results in the formation of a steep intensity gradient at the front of the pulse. A more unstable bubble structure, the self-injections in different positions, and high dark current are the results of using a positively chirped laser pulse. For a negatively chirped laser pulse, the pulse depletion process is compensated during the propagation of the pulse in plasma in such a way that results in a more stable bubble shape and therefore, a localized electron bunch is produced during the acceleration process. As a result, by the proper choice of chirping, one can tune the number of self-injected electrons, the size of accelerated bunch

关键词： bubble regime plasma wake field positively chirped laser pulse

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Study on flaw identification of ultrasonic signal for large shafts based on optimal support vector machine

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仪器仪表学报 2008年第5期29卷 908-913页

作者： Zhao Xiufen yin guofu Tian guiyun yin ying College of Manufacturing Science and Engineering Sichuan University Chengdu 610065 China School of Electrical Electronic and Computer Engineering University of Newcastle UK

Automatic identification of flaws is very important for ultrasonic nondestructive testing and evaluation of large shaft.A novel automatic defect identification system is *** packet analysis(WPA)was applied to feature extraction of ultrasonic signal,and optimal Support vector machine(SVM)was used to perform the identification ***,comparative study on convergent velocity and classified effect was done among SVM and several improved BP network *** validate the method,some experiments were performed and the results show that the proposed system has very high identification performance for large shafts and the optimal SVM processes better classification performance and spreading potential than BP manual neural network under small study sample condition.

关键词：裂纹鉴别技术超声波转轴支持向量机

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Proton-neutron symplectic model description of ^(20)Ne

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Chinese Physics C 2022年第4期46卷 141-149页

作者： h.g.ganev Joint Institute for Nuclear Research DubnaRussia

A microscopic description of the low-lying positive-parity rotational bands in ^(20)Ne is given within the framework of the symplectic-based proton-neutron shell-model approach provided by the proton-neutron symplectic model(PNSM).For this purpose,a model hamiltonian is *** includes an algebraic interaction lying in the enveloping algebra of the Sp(12,R)dynamical group of the PNSM,which introduces both horizontal and vertical mixings of different SU(3)irreducible representations within the Sp(12,R)irreducible collective space of ^(20)Ne.A good overall description is obtained for the excitation energies of the ground and first two excited β bands,including the ground state intraband B(E2)quadrupole collectivity and the known interband B(E2)transition probabilities between the low-lying collective states,without utilizing an effective charge.

关键词： proton-neutron symplectic model shell-model states collective states in^(20)Ne

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Matrix elements in the SU(1,1)⊗SO(6)limit of the proton-neutron symplectic model

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Chinese Physics C 2021年第11期45卷 101-114页

作者： h.g.ganev Joint Institute for Nuclear Research DubnaRussia

The matrix elements along the reduction chain Sp(12,R)⊃SU(1,1)⊗SO(6)⊃U(1)⊗SUpn(3)⊗SO(2)⊃SO(3)of the proton-neutron symplectic model(PNSM)are *** analytical expressions are obtained for the matrix elements of the basic building blocks of the PNSM and the Sp(12,R)symplectic generators,allowing the computation of matrix elements of other physical operators as *** computational technique developed in the present study generally provides us with the required algebraic tool for performing realistic symplectic-based shell-model calculations of nuclear collective *** two simple examples,we illustrate the application of the theory.

关键词： matrix elements proton-neutron symplectic model SU(1 1)⊗SO(6)limit Sp(12 R)dynamical algebra

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Study on radiolabeling of 1,2,3-triazole analogs with fac-[^(188)Re(CO)_3 (h_2O)_3 ]^+ via click chemistry

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Nuclear Science and Techniques 2013年第3期24卷 27-30页

作者： WANg Cheng yin Jilin ZhOU Wei ZhANg Lan ZhOU Zheng PET/CT center General Hospital of Guangzhou Military Command Shanghai Institute of Applied Physics Chinese Academy of SciencesJiading Campus

Click chemistry was used to study on radiolabeling of 1,2,3-triazole analogs with fac-[188 Re(CO) 3 (h 2 O) 3]+ . CuSO 4 /L-sodium ascorbate was chosen as the catalyst system, three terminal alkynes were conjugated with two different azides respectively, and then the new prepared fac-[188 Re(CO) 3 (h 2 O) 3]+ was coordinated to the six triazoles. The results showed that the radiochemical yields (RCY) of the conjugation of fac-[188 Re(CO) 3]+ with six triazoles were over 90%, and the triazoles showed high stability in phosphate-buffered saline and new-born calf serum. The preliminary biological evaluation results showed that the new 188 Re-labeling method via click chemistry could have general application in labeling bioactive molecules in high radiochemical yield and high specific activity for further SPECT research.

关键词：化学研究三唑类类似物 CO 生物活性评价生物活性分子化学产率催化剂体系

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ThE ELECTROChEMICAL BEhAVIOR OF OCEANIC MICROBIOLOgICAL INFLUENCED CORROSION ON CARBON STEEL

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Acta Metallurgica Sinica(English Letters) 2007年第5期20卷 334-340页

作者： X.T. Chang Y.S. yin g.h. Niu T. Liu S. Cheng S.B. Sun Institute of Materials Science and Technology Ocean University of China Qingdao 266003 China College of Materials Science and Technology Shandong University Jinan 250061 China

The corrosion behavior of carbon steel in the medium of marine microorganisms was investigated by electrochemical impedance spectra, polarization curves, and so on. Experimental results showed that the corrosion potential of carbon steel moved in a negative direction in the unpurified marine microorganism solution, and the polarization style of the cathodic process did not change. The electrochemical impedance spectra showed that the impedance value of the electrode decreased in the medium with bacteria, which indicated that the existence of microorganism could accelerate the corrosion progress of carbon steel.

关键词： carbon steel microbiological influenced corrosion polarization curve electrochemical impedance spectroscopy

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Microscopic shell-model description of irrotational-flow dynamics in^(102)Pd

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Chinese Physics C 2024年第1期48卷 82-93页

作者： h.g.ganev Joint Institute for Nuclear Research DubnaRussia Institute of Mechanics Bulgarian Academy of SciencesSofiaBulgaria

The structure of the low-lying collective excitations in 102Pd is examined within the recently proposed microscopic shell-model version of the Bohr-Mottelson(BM)collective model.A good description of the excitation energies of the lowest ground,γ,andβbands,as well as the staggering function between the collective states of theγband and some other energy-dependent quantities,is *** low-energy intraband and interband quadrupole dynamics is reasonably well described within the present proton-neutron sympletic based shell-model approach without the use of an effective charge and compared with the predictions of nuclear structure *** obtained results of the present study shed light on the question of the existence of irrotational-flow type quadrupole dynamics,which lies on the ground of the original BM model of quantized vibrations and surface-wave rotations in atomic nuclei.

关键词： shell-model version of the Bohr-Mottelson model irrotational-flow dynamics proton-neutron symplectic model Sp(12,R)dynamical algebra

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A new type of cell related to organ movement for selfing in plants

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National Science Review 2023年第9期10卷 190-203页

作者： yin-Zheng Wang Yan-Xiang Lin Qi Liu Jing Liu Spencer C.h.Barrett State Key Laboratory of Systematic and Evolutionary Botany Institute of BotanyChinese Academy of Sciences China National Botanical garden College of Life Sciences University of Chinese Academy of Sciences College of Pharmacy Fujian University of Traditional Chinese Medicine Department of Ecology and Evolutionary Biology University of Toronto

Many plants employ osmotic and hydrostatic pressure to generate movement for survival,but little is known about the cellular mechanisms ***,we report a new cell type in angiosperms termed ’contractile cells’ in the stigmas of the flowering plant Chirita pumila with a much-expanded rough endoplasmic reticulum(RER).Cryo-scanning electron microscopy and transmission electron microscopy analyses revealed that the RER is continuously distributed throughout the entirety of cells,confirmed by endoplasmic reticulum(ER)-specific fluorescent labeling,and is distinct from the common feature of plant *** RER is water-sensitive and extremely elongated with water *** show that the contractile cells drive circadian stigma closing-bending movements in response to day-to-night moisture ***-seq analyses demonstrated that contractile cells have distinct molecular ***,multiple microstructural changes in stigma movements convert an anti-selfing structure into a device promoting selfing—a unique cellular mechanism of reproductive adaptation for uncertain pollination environments.

关键词： stigma movement rough endoplasmic reticulum contractile cells circadian moisture changes reproductive transition

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