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Effect of samarium oxide on structural,optical and electrical properties of some alumino-borate glasses with constant copper chloride

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Journal of Rare Earths 2020年第7期38卷 770-775,I0004页

作者： M.S.Sadeq h.y.Morshidy Basic Sciences Dept. Faculty of EngineeringSinai Univ.45511Al-ArishEgypt

The glass system under study was prepared and examined using the melt quenching procedures and XRD to emphasize the amorphous nature,*** of the prepared solid glass system was performed by a spectrophotometer in wavelengths from 190 to 1099 *** traditional techniques and standard formulas,the density,molar volume,refractive index,optical band gap and the optical filter characteristics were determined,then the influence of samarium oxide on some properties like the structure and optical,also the electrical properties were dissected.A novel formula was proposed to estimate the refractive index from the optical energy *** obtained samples are good optical filters especially the sample that contains 0.8 mol% of Sm2 *** this sample has the utmost density,the least molar volume,the maximum transmittance,least refractive index,the highest optical band gap and the least dc conductivity.

关键词： Alumino borate glasses Samarium oxide Optical properties Rare earths

One-dimensional Ga N nanomaterials transformed from one-dimensional Ga_2O_3 and Ga nanomaterials

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Nano-Micro Letters 2009年第1期1卷 4-8页

作者： X.y.han y.h.Gao X.h.Zhang Wuhan National Laboratory for Optoelectronics-Shool of Physics Huazhong University of Science and Technology Wuhan National Laboratory for Optoelectronics & Col ege of Optoelectronic Science and Engineering Huazhong University of Science and Technology

One-dimensional(1D) GaN nanomaterials exhibiting various morphologies and atomic structures were prepared via ammoniation of either Ga_2O_3 nanoribbons, Ga_2O_3 nanorods or Ga nanowires filled into carbon nanotubes(CNTs). The 1D GaN nanomaterials transformed from Ga_2O_3 nanoribbons consisted of numerous GaN nanoplatelets having the close-packed plane, i.e.(0002)2h or(111)3C parallel to the axes of starting nanoribbons. The 1D GaN nanomaterials converted from Ga_2O_3 nanorods were polycrystalline rods covered with GaN nanoparticles along the axes. The 1D GaN nanomaterials prepared from Ga nanowires filled into CNTs displayed two dominant morphologies:(i) single crystalline Ga N nanocolumns coated by CNTs, and(ii) pure single crystalline Ga N nanowires. The cross-sectional shape of Ga N nanowires were analyzed through the transmission electron microscopy(TEM) images. Formation mechanism of all-mentioned 1D GaN nanomaterials is then thoroughly discussed.

关键词： GaN One-dimensional Ga2O3 Nanostructures

EFFECT OF CERIUM ION IMPLANTATION ON ThE AQUEOUS CORROSION BEhAVIOR OF ZIRCONIUM

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Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 812-816页

作者： D.Q.Peng X.D.bai Q.G.Zhou X.W.Chen R.h.yu X.y.Liu DepartmentofMaterialsScienceandEngineering TsinghuaUniversityBeijing100084ChinaManuscriptreceived9September2003

In order to study the influence of cerium ion implantation on the aqueous corrosion behavior of zirconium, specimens were implanted by cerium ions with a dosage range from 1×1016 to 1×1017 ions/cm2 at about 150℃, using MEVVA source at an acceler ative voltage of 40kV. The valence of the surface layer was analyzed by X-ray photo- electron spectroscopy (XPS); Three-sweep potentiodynamic polarization measurement was employed to value the aqueous corrosion resistance of zirconium in a 0.5mol/L h2SO4 solution. It was found that a remarkable decline in the aqueous corrosion behavior of zirconium implanted with cerium ions compared with that of the as-received zirconium. Finally, the mechanism of the corrosion resistance decline of the cerium-implanted zirconium is discussed.

关键词： zirconium corrosion resistance cerium ion implantation potentio- dynamic polarization X-ray photoelectron spectroscopy (XPS)

First principles calculations on the thermoelectric properties of bulk Au2S with ultra-low lattice thermal conductivity

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Chinese Physics B 2020年第8期29卷 108-114页

作者： y y Wu X L Zhu h y yang Z G Wang y h Li B T Wang School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China Institute of high Energy Physics Chinese Academy of SciencesBeijing 100049China Spallation Neutron Source Science Center Dongguan 523808China School of Materials Science and Engineering Hunan University of Science and TechnologyXiangtan 411201China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Sulfide nanocrystals and their composites have shown great potential in the thermoelectric(TE)field due to their extremely low thermal *** a solid and hollow metastable Au2S nanocrystalline has been successfully ***,we study the TE properties of this bulk Au2S by first-principles calculations and semiclassical Boltzmann transport theory,which provides the basis for its further experimental *** results indicate that the highly twofold degeneracy of the bands appears at theΓpoint in the Brillouin zone,resulting in a high Seebeck ***,Au2S exhibits an ultra-low lattice thermal conductivity(~0.88 W·m^-1·K^-1 at 700 K).At 700 K,the thermoelectric figure of merit of the optimal p-type doping is close to 1.76,which is higher than 0.8 of ZrSb at 700 K and 1.4 of PtTe at 750 *** work clearly demonstrates the advantages of Au2S as a TE material and would greatly inspire further experimental studies and verifications.

关键词： first principles calculation thermodynamic transport properties

ON FATIGUE CRACK PATh DEVIATION AT ELEVATED TEMPERATURE IN ELECTRON BEAM REPAIRED WELDMENTS OF TURBINE DISK

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 584-590页

作者： h.Q.Zhang h.y.Zhao y.h.Zhang L.h.Li X.A.Zhang Department of Mechanical Engineering Tsinghua University Beijing 100084 ChinaDepartment of Mechanical Engineering Tsinghua University Beijing 100084 ChinaSchool of Mechanical Engineering and Automation Beijing University of Aeronautics and AstronauticsBeijing 100083 ChinaSchool of Mechanical Engineering and Automation Beijing University of Aeronautics and AstronauticsBeijing 100083 ChinaBeijing Institute of Aeronautical Materials Beijing 100095 China

Fatigue crack growth behaviors in electron beam weldments of a nickel-base superalloy are studied. The objective of this paper is to discuss effects of the inhomogeneity of mechanical performance on fatigue crack growth (FCG) rate and crack path deviation (CPD). The base metal served in a turbine disk of aerospace engine was selected to fabricate bead-on-plate weldments by using electron beam welding. Some wedge-type opening loading specimens, notched in three different zone of weld metal, hAZ and base metal, were employed and performed fatigue crack growth tests at 650℃. The results show that the fatigue crack growth of electron beam welded joints is instable due to the influence of mechanical heterogeneities. Owing to the crack deviation at the weld metal and heat-affected-zone (hAZ), the effective growth driving force at the tip of fatigue crack was reduced with the reduction of the effective stress intensity factor (SIF) which finally causes fatigue crack rate decrease. Fatigue crack was strongly affected by size and the symmetrical characteristics of the plastic zone at the crack tip, which means that the integrity of the welded structure containing the fatigue crack mainly depended on the toughness of the low strength zone.

关键词： fatigue crack growth crack path deviation electron beam welding inhomogeneity of mechanical performance

Nowcasting and Forecasting Seasonal Influenza Epidemics—China,2022-2023

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China CDC weekly 2023年第49期5卷 1100-1106,I0003-I0005页

作者： Zhanwei Du Zengyang Shao Xiao Zhang Ruohan Chen Tianmu Chen yuan bai Lin Wang Eric h.y.Lau Benjamin J.Cowling WhO Collaborating Center for Infectious Disease Epidemiology and Control School of Public HealthLKS Faculty of MedicineThe University of Hong KongHong Kong Special Administrative RegionChina Laboratory of Data Discovery for health Limited Hong Kong Science and Technology ParkHong Kong Special Administrative RegionChina State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics School of Public HealthXiamen UniversityXiamen CityFujian ProvinceChina Department of Genetics University of CambridgeCambridgeUK Institute for health Transformation&School of health&Social Development Deakin UniversityMelbourneAustralia

Background:Seasonal influenza resurged in China in February 2023,causing a large number of *** influenza epidemics occurred across China during the coronavirus disease 2019(COVID-19)pandemic,the relaxation of COVID-19 containment measures in December 2022 may have contributed to the spread of acute respiratory infections in winter 2022/***:Using a mathematical model incorporating influenza activity as measured by influenza-like illness(ILI)data for northern and southern regions of China,we reconstructed the seasonal influenza incidence from October 2015 to September 2019 before the COVID-19 *** this trained model,we predicted influenza activities in northern and southern China from March to September ***:We estimated the effective reproduction number Re as 1.08[95%confidence interval(CI):0.51,1.65]in northern China and 1.10(95%CI:0.55,1.67)in southern China at the start of the 2022-2023 influenza *** estimated the infection attack rate of this influenza wave as 18.51%(95%CI:0.00%,37.78%)in northern China and 28.30%(95%CI:14.77%,41.82%)in southern ***:The 2023 spring wave of seasonal influenza in China spread until July 2023 and infected a substantial number of people.

关键词： winter relaxation measures

APPLICABILITy OF CREEP CONSTITUTIVE EQUATIONS TOCREEP CURVES UNDER CONSTANT LOAD

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Acta Metallurgica Sinica(English Letters) 1998年第6期11卷 397-404页

作者： y.Kurata h.Utsumi Japan Atomic Energy Research Inst Ibaraki-ken Japan

Applicability of the following creep constitutive equations was investigated for normal type creep curves of Ni-18.5Cr alloy and tertiary creep dominant curves of Ni-18.5Cr16W alloy under constant load: the θ projection method describing a creep curse by a sum of two exponential terms, modified θ method describing a primary creep stage by an exponential term and a tertiary creep stage by a logarithmic term, modified Ω method describing a creep curve by a sum of two logarithmic term, 2θ method with only a tertiary creep component and Ω method. The θ, modified θ and modified Ω methods can describe normal type and tertiary creep dominant curves. Tertiary creep dominant curves of Ni-18.5Cr-16W alloy at 900℃ are also described using 2θ and Ω methods. Applicability of the modified θ and modified Ω methods is superior for constant load creep curves because they can predict creep curves up to rupture and rupture life accurately and conservatively.

关键词： creep equation θ projection method Ω method Ni-18.5Cr alloy,Ni-18.5Cr-16W alloy

The Cauchy problem for non-autonomous nonlinear Schr(o)dinger equations

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Science China Mathematics 2005年第4期48卷 522-538页

作者： Peter y. h. Pang Department of Mathematics

In this paper we study the Cauchy problem for cubic nonlinear Schr(o)dinger equation with space-and time-dependent coefficients on Rm and Tm. By an approximation argument we prove that for suitable initial values, the... 详细信息

关键词： non-autonomous Schr(o)dinger equations, local existence, global existence.

Creep Behavior and Microstructure Evolution of Sand–Cast Mg–4y–2.3Nd–1Gd–0.6Zr Alloy Crept at 523–573 K

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Journal of Materials Science & Technology 2017年第1期33卷 79-89页

作者： y.h.Kang h.yan R.S.Chen The Group of Magnesium Alloys and Their Applications Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China University of the Chinese Academy of Sciences Beijing 100049China

high temperature tensile-creep behavior of Mg-4y-2.3Nd-IGd-O.6Zr （wt%, WE43（T6）） alloy at 523- 573 K was investigated. The creep stress exponent is equal to 4.6, suggesting the underlying dislocation creep mechanism. The activation energy is （199 _＋ 23） kJ/mol, which is higher than that for self- diffusion in Mg and is believed to be associated with precipitates coarsening or cross slip. The creep mechanism is further suggested to be dislocation climb at 523 K, while a cross slip at 573 K is possible. The metastable 13＇ and ~]1 phases in the WE43（T6） alloy were relatively thermal stable at 523 K and could be effective to hinder the dislocation climb, which contributed to its excellent creep resistance. however, at 573 K it readily transforms into equilibrium/3e phase and coarsens within two hours, thereby causing a decrease of creep resistance. In addition, precipitate free zones approximately normal to applied stress direction （directional PFZs） developed during the creep deformation, especially at 573 K. Those zones became preferential sites to nucleate, extend and connect microcracks and cavities, which lead to the intergranular creep fracture. Improving the thermal stability of precipitates or introducing thermally stable fine plate-shaped precipitates on the basal planes of Mg matrix could enhance the high temperature creep resistance.

关键词： WE43 alloy Creep PFZs Precipitate Fracture