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Sodium lanthanide fluoride core-shell nanocrystals： A general perspective on epitaxial shell growth

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Nano Research 2013年第8期6卷 547-561页

作者： Noah j. j. johnson Frank C. j. M. van Veggel Department of Chemistry University ofVictoria P.O. Box3065 Victoria British Columbia Canada V8W 3V6

Understanding the structural characteristics and growth mechanism（s） are essen-tial for generating core-shell nano-heterostructures with distinctive properties. Especially in lanthanide-based nanocrystals, rational design of the core-shell composition can be utilized to enhance/tune the optical properties of the final nanostructure, or can be used to integrate multiple functional applications （e.g., luminescent/magnetic）. In this article, we review the progress in our current understanding of the epitaxial shell growth in sodium lanthanide fluoride （NaLnF4） nanocrystals. In order to understand epitaxial shell growth the core nanocrystals have to be uniform, and to date the synthesis of high quality near uniform size/shape dispersion controlled synthesis of lanthanide-based nanocrystals has been achieved mainly with this class of nanocrystals. The progress in core-shell synthesis and the epitaxial shell growth mechanism in this class of nanocrystals （NaLnF4） are reviewed, and a general perspective is provided on the core-shell morphology based on different characterization techniques. While there has been tremendous progress in studying the impact of core-shell structures in various functional applications, this review also highlights, in our view, the still limited understanding of ways to control the core-shell morphology and it emphasizes some important, unanswered questions that remain to be addressed to maximize their performance.

关键词： upconvertingnanocrystals core-shell lanthanides epitaxy

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文化定位与高中生饮酒行为之间的关系

中国行为医学科学 2005年第11期14卷 1019-1020页

作者：薛建平 Ian M Newman Duane F shell 方晓义美国内不拉斯加大学教育和人类科学学院教育心理系北京师范大学发展心理研究所

目的旨在探讨文化和饮酒之间的关系。方法于2002年1月对北京市5所高中的1091名高一至高三学生用文化定位量表和饮酒行为量表进行了匿名问卷调查。结果三类不同饮酒行为组的文化定位均值之间差异有显著性(F=30.64,P=0.03)。两两比较的结... 详细信息

目的旨在探讨文化和饮酒之间的关系。方法于2002年1月对北京市5所高中的1091名高一至高三学生用文化定位量表和饮酒行为量表进行了匿名问卷调查。结果三类不同饮酒行为组的文化定位均值之间差异有显著性(F=30.64,P=0.03)。两两比较的结果表明这种差异表现在非饮酒组[(2.98±0.28)分]和偶尔饮酒组[(3.08±0.27)分]、非饮酒组和经常饮酒组[(3.13±0.26)分]之间。结论本调查结果表明,越“西方”化的学生越可能成为饮酒者,越“传统”化的学生成为饮酒者的可能性越低,同时它也表明西方文化可能对我国青少年的饮酒行为有影响。

关键词：文化定位高中生饮酒行为身体健康

Synthesis and Characterization of Nanocapsules of α-Fe(NiCoAl) Solid-solution

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journal of Materials Science & Technology 2005年第3期21卷 297-300页

作者： DianyuGENG j.C.Kim C.j.Cho ChonglinCHEN XianguoZHAO ZidongZHANG ShenyangNationalLaboratoryforMaterialsScience InstituteofMetalResearchandInternationalCentretbrMaterialsPhysicsChineseAcademyofSciencesShenyang110016China KoreaInstituteofMachineryandMaterials 66Sangnam-dongChangwonKynugnam640-010SouthKorea

α-Fe(NiCoAl) solid-solution nanocapsules were prepared with pure powders of Fe, Ni, Co and Al by the plasma arc-discharging using a copper crucible. The shapes of the nanocapsules are in polyhedrons with the core/shell structure. The body centered cubic (BCC) phase is formed in the core. The size of the nanocapsules is in the range of 10-120 nm and the thickness of the shell is 4-11 nm. Saturation magnetization jS=150 Am2/kg and coercivity iHC=24.3 kA/m are achieved for the nanocapsules.

关键词： Nanocapsules a-Fe solid solution Plasma arc discharge Magnetic properties

A Space-Time Interior Penalty Discontinuous Galerkin Method for the Wave Equation

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Communications on Applied Mathematics and Computation 2022年第3期4卷 904-944页

作者： Poorvi Shukla j.j.W.van der Vegt Department of Applied Mathematics University of TwenteP.O.Box 2177500 AE EnschedeThe Netherlands

A new higher-order accurate space-time discontinuous Galerkin(DG)method using the interior penalty flux and discontinuous basis functions,both in space and in time,is pre-sented and fully analyzed for the second-order scalar wave *** attention is given to the definition of the numerical fluxes since they are crucial for the stability and accuracy of the space-time DG *** theoretical analysis shows that the DG discre-tization is stable and converges in a DG-norm on general unstructured and locally refined meshes,including local refinement in *** space-time interior penalty DG discre-tization does not have a CFL-type restriction for *** order of accuracy is obtained in the DG-norm if the mesh size h and the time stepΔt satisfy h≅CΔt,with C a positive *** optimal order of accuracy of the space-time DG discretization in the DG-norm is confirmed by calculations on several model *** calculations also show that for pth-order tensor product basis functions the convergence rate in the L∞and L2-norms is order p+1 for polynomial orders p=1 and p=3 and order p for polynomial order p=2.

关键词： Wave equation Space-time methods Discontinuous Galerkin methods Interior penalty method A priori error analysis

Material and structural instabilities of single-wall carbon nanotubes

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Acta Mechanica Sinica 2008年第3期24卷 285-288页

作者： j.Wu K.C.Hwang j.Song Y.Huang FML Department of Engineering MechanicsTsinghua UniversityBeijing 100084China Department of Mechanical Science and Engineering University of Illinois1206 W.Green StreetUrbanaIL 61801USA Department of Civil and Environmental Engineering and Department of Mechanical Engineering Northwestern UniversityEvanstonIL 60208USA

The nonlinear atomistic interactions usually involve softening behavior. Instability resulting directly from this softening are called the material instability, while those unrelated to this softening are called the structural instability. We use the finite-deformation shell theory based on the interatomic potential to show that the tension instability of single-wall carbon nanotubes is the material instability, while the compression and torsion instabilities are structural instability.

关键词： Carbon nanotubes Instability

Collective Bands in the Neutron—Rich 110Ru Nucleus

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Chinese Physics Letters 2003年第3期20卷 350-353页

作者：姜卓 j.H.Hamilton 等 DepartmentofPhysics TsinghuaUniversityBeijing100084 DepartmentofPhysics VanderbiltUniversityNashvilleTN37235USA

High spin states in neutron-rich 110Ru nucleus have been investigated by measuring high-fold prompt γ-ray coincidence events of the spontaneous fission of 252Cf with the Gammasphere detector array. The ground-state band and the γ-vibrational band have been confirmed and extended with spin up to 18 and 13, respectively. The other three side bands, two proposed as two-quasiparticle bands and one proposed as a four-quasiparticle band, have been observed for the first time. The possible configurations for the quasi-particle bands are discussed. The cranked shell model calculations show that 110Ru nucleus may have oblate triaxial deformation with parameters β2 = -0.30 and γ = 24°, and the band crossing in the yrast band is due to the alignment of a pair of h11/2 neutrons.

关键词： Gamma rays

Ultrasound-triggered directional release from turmeric capsules

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Particuology 2021年第4期19卷 19-27页

作者： Tomasz Kubiak Maja Zubko Arkadiusz józefczak Chair of Acoustics Faculty of PhysicsAdam Mickiewicz University in PoznańUniwersytetu Poznańskiego 261-614 PoznańPoland Hipolit Cegielski State University of Applied Sciences Stefana Wyszyńskiego 3862-200 GnieznoPoland

The scientific interest in capsules with the shell composed of fused microparticles is still growing due to a large number of practical ***-designed capsules should ensure the safe cargo delivery and facilitate its controlled release on *** biocompatibility and biodegradability are additional essential features of structures intended for biomedical *** paper presents two kinds of ultrasound sensitive capsules:the first type with the homogeneous shell made of a monolayer of fine turmeric granules,and the other with janus shell composed of two different materials *** granules and synthetic polystyrene *** demonstrated that plane ultrasonic waves with low intensity and high frequency and also focused ultrasound can act as a trigger for smooth liberation of a liquid cargo,in our case,the dispersion of probiotic *** ultrasound-induced puncture of the shell was followed by unidirectional and controlled release of encapsulated *** case of janus structures,in addition to sonication time and ultrasound frequency,distinct mechanical properties of two shell regions also influenced the course of content liberation *** expect that the use of natural material such as turmeric granules for the formation of the shells of the ultrasound-responsive capsules can further increase the range of their potential applications.

关键词： Ultrasound-responsive capsules Turmeric shells janus capsules Controlled release

Synthesis and Magnetic Properties of Nanoparticles of Fe-Co Alloys and Their Oxides Prepared by Chemical Vapor Condensation

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journal of Materials Science & Technology 2004年第4期20卷 459-462页

作者： ZhenhuaWANG ZhidongZHANG C.j.Choi B.K.Kim j.C.Kim ShenyangNationalLaboratoryforMaterialsScienceandInternationalCentreforMateri~alsPhysics InstituteofMetalResearchChineseAcademyofSciencesShenyang110016China KoreaInstituteofMachineryandMaterials 66Sangnam-DongChangwonKyungnam641-010Korea

Nanoparticles of Fe-Co alloys and their oxides with the particle size below 20 nm were prepared by chemical vapor condensation process. The pure Ar, Ar+1%O2, Ar+3%O2 and Ar+6%O2 were used as carrier gases, with iron carbonyl and cobalt carbonyl as the precursors. XRD patterns showed that Fe-Co metallic nanoparticles were synthesized by using pure Ar as carrier gas, and only metal oxides were obtained using Ar+(>3)%O2 as carrier gas. The HRTEM images and TG-DTA curves were used to study the core-shell structure of the different nanoparticles. The nanoparticles obtained in pure Ar consist of black core and light shell with thickness of 2~4 nm. However, in the particles obtained in Ar+6%02, the oxides core with visible lattice fringes are surrounded by thin shell.

关键词： Fe-Co Nanoparticles HRTEM CVC

Tuning the morphologies of SiC nanowires via the change of the Co_xSi_y melts

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Nano-Micro Letters 2010年第1期2卷 11-17页

作者： j.j.Chen Y.Pan W.H.Tang Q.Shi Department of Physics Center for Optoelectronics Materials and Devices Zhejiang Sci-Tech University Department of Materials Science and Engineering Zhejiang University Key Laboratory of Advanced Textile Materials and Manufacturing Technology (Zhejiang Sci-Tech University) Ministry of education

SiC nanowires and SiC/SiO2 core-shell structural nanowires were synthesized via a simple thermal evaporation of CoxSiy melts at the temperature of 1500?C. The morphologies and yields of those SiC nanowires can be tuned by altering the composition of CoxSiy. Nanowires obtained by thermal evaporation of Co Si are composed of SiC/SiO2 core-shell nanostructures with lengths up to several hundreds of micrometers, diameters of 4050 nm, and the thickness of amorphous SiO2 wrapping shell about 20 nm. SiC nanowires prepared by thermal evaporation of Co Si2 and Co2 Si melt are found to be hexagonal-prism-shaped nanorods, and the diameter of those nanorods is about 150 nm and the length is about 10 microns. All the SiC nanowires obtained possess [111] preferred growth direction with a high density stacking faults and twin defects. Taking into consideration the binary alloy diagram of Co Si and the participation of oxygen, we propose the vapor-solid growth mechanism of SiC nanowires and discuss the effect of the supersaturation of Si O on the morphology and yields of SiC nanowires.

关键词： Silicon carbide Nanowires Morphology