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101.
C. Gonzlez-Santander F. Domínguez-Adame 《Physica E: Low-dimensional Systems and Nanostructures》2009,41(9):1645-1647
We study the exciton states in a parabolic quantum wire. An exactly solvable model is introduced for calculating the exciton state and the binding energy as a function of the radius of the quantum wire within the envelope-function approximation. In the calculation, we replace the actual Coulomb interaction between the electron and the hole by a Gaussian nonlocal separable potential and obtain closed expressions for both the envelope-function and the binding energy. Results are compared with those obtained by perturbative methods. 相似文献
102.
A. Pundt M. Dornheim M. Guerdane H. Teichler H. Ehrenberg M.T. Reetz N.M. Jisrawi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(3):333-337
An in situ synchrotron radiation study of quasi-free five nanometer-sized palladium clusters during hydrogen absorption is combined
with molecular dynamics simulations to investigate the structural development. In the diffraction patterns, strong intensity
changes are found that provide evidence for a structural phase transformation that is significantly different from the α--Pd-H bulk phase transition. The structural transition is reversible and driven by the hydrogen concentration. The intensity
changes are consistent with a cubic-to-icosahedral structural phase transition obtained in molecular dynamical simulations
using embedded-atom-method potentials.
Received 15 October 2001 and Received in final form 7 February 2002 相似文献
103.
M. N. Kozicki M. Mitkova M. Park M. Balakrishnan C. Gopalan 《Superlattices and Microstructures》2003,34(3-6):459
Programmable metallization cell (PMC) memory is based on the electrochemical control of nanoscale quantities of metal in thin films of solid electrolyte. It shows great promise as an ultra-scalable solid state non-volatile memory as it requires low programming voltage and current, and has the ability for the storage cells to be physically sized at minimum lithographically defined dimensions. Scalability issues will be discussed in the context of recent findings relating to the nanostructure of the electrolyte and results obtained from small-geometry devices based on Ag–Ge–Se nano-phase separated material. 相似文献
104.
N. Pinçon B. Palpant D. Prot E. Charron S. Debrus 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(3):395-402
We report a study on the third-order nonlinear optical properties of nanocomposite thin films composed of gold particles embedded
in a silica host matrix. Samples of various metal volume fractions, ranging from 8 to 35%, are synthesized by the sputtering
technique. Some of them are annealed. Nonlinear optical measurements, which are performed by using the z-scan technique, reveal both a very large nonlinear absorption and a weak nonlinear refraction close to the surface plasmon
resonance frequency of the particles. We especially study the effect of the metal concentration and the influence of thermal
treatment on the real and imaginary components of the third-order nonlinear susceptibility. Our results reveal that, as the
metal concentration reaches a few percent, the mutual electromagnetic interactions between particles greatly enlarge the nonlinear
optical response of the material and can not be neglected in the theoretical analysis. Moreover, the thermal treatment leads,
for a given concentration, to a significant increase of the nonlinear response, which is ascribed to a modification of the
material morphology. We finally point out that the material nonlinear properties are very sensitive to the incident wavelength
through the local field enhancement phenomenon.
Received 12 December 2001 相似文献
105.
《中国化学快报》2020,31(5):1060-1070
In the past decade,nanoscale metal-organic frameworks(nMOFs) have drawn a great attention due to their high porosity,wide range of pore shapes,tunable frameworks and relatively low toxic.With the development of nanotechnology,many researchers studied the synthesis,characterization,functionalization and biotoxicity of nMOFs,and a more thorough understanding was developed about numerous nMOFs as promising platforms for biomedical applications.This review highlights the up-to-date progress of nMOFs related to their bio-applications such as drug delivery,bioimaging,biosensing and biocatalysis,and the common surface modification methods we re classified into four categories:covalent post-synthetically modification,coordinative post-synthetically modification,noncovalent postsynthetically modification and modification on the external surface.At the same time,the challenges and perspectives of nMOFs were discussed as well. 相似文献
106.
The interest in effects of strontium (Sr) on bone has greatly increased in the last decade due to the development of the promising drug strontium ranelate. This drug is used for treating osteoporosis, a major bone disease affecting hundreds of millions of people worldwide, especially postmenopausal women. The novelty of strontium ranelate compared to other treatments for osteoporosis is its unique effect on bone: it simultaneously promotes bone formation by osteoblasts and inhibits bone resorption by osteoclasts. Besides affecting bone cells, treatment with strontium ranelate also has a direct effect on the mineralized bone matrix. Due to the chemical similarities between Sr and Ca, a topic that has long been of particular interest is the incorporation of Sr into bones replacing Ca from the mineral phase, which is composed by carbonated hydroxyapatite nanocrystals. Several groups have analyzed the mineral produced during treatment; however, most analysis were done with relatively large samples containing numerous nanocrystals, resulting thus on data that represents an average of many crystalline domains. The nanoscale analysis of the bone apatite crystals containing Sr has only been described in a few studies. In this study, we review the current knowledge on the effects of Sr on bone mineral and discuss the methodological approaches that have been used in the field. In particular, we focus on the great potential that advanced microscopy and microanalytical techniques may have on the detailed analysis of the nanostructure and composition of bone apatite nanocrystals produced during treatment with strontium ranelate. 相似文献
107.
纳米TiO_2-ZnO二元负载木材的制备及性质 总被引:1,自引:0,他引:1
采用两步法将TiO_2/ZnO纳米材料与杨木试样复合,制备了纳米二元负载木材.通过X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)和扫描电子显微镜(SEM)对样品的结构和形貌进行了表征,并探讨了不同处理条件下得到的纳米氧化物负载木材及非纳米氧化物负载木材的抗菌性和耐候性.结果表明,氧化锌和二氧化钛二元协同负载木材的抗菌性和耐候性均优于单一纳米晶处理的木材;在溶剂热反应中以正己烷作为溶剂所制备样品的性能优于以水和无水乙醇为溶剂制备的样品;并且纳米结构负载木材的抗菌性和耐候性优于非纳米结构负载的木材. 相似文献
108.
Non-crystalline structures in the growth of silver nanoclusters 总被引:2,自引:0,他引:2
F. Baletto C. Mottet R. Ferrando 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):25-28
The growth of nanometer-size free Ag clusters is studied by Molecular Dynamics simulations. The morphology transition from
the icosahedron at the magic size of N = 55 atoms to the Marks truncated decahedron at N = 75 is analyzed in details, in order to single out kinetic trapping and entropic effects. At very low T, the cluster is kinetically trapped in an icosahedral structure. At intermediate T the transition takes place sharply at N≃ 65. At higher T, the transition is smeared out and finally, around 550 K no transition is found because the 75 decahedron is melted.
Received 28 November 2000 相似文献
109.
W.L. Zhou E.E. Carpenter J. Lin A. Kumbhar J. Sims C.J. O'Connor 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):289-292
Pure metal iron nanoparticles are unstable in the air. By a coating iron on nanoparticle surface with a stable noble metal,
these air-stable nanoparticles are protected from the oxidation and retain most of the favorable magnetic properties, which
possess the potential application in high density memory device by forming self-assembling nanoarrays. Gold-coated iron core-shell
structure nanoparticles (Fe/Au) synthesized using reverse micelles were characterized by transmission electron microscopy
(TEM). The average nanoparticle size of the core-shell structure is about 8 nm, with about 6 nm diameter core and 1∼2 nm shell.
Since the gold shell is not epitaxial growth related to the iron core, the morié pattern can be seen from the overlapping
of iron core and gold shell. However, the gold shell lattice can be seen by changing the defocus of TEM. An energy dispersive
X-ray spectrum (EDS) also shows the nanoparticles are air-stable. The magnetic measurement of the nanoparticles also proved
successful synthesis of gold coated iron core-shell structure. The nanoparticles were then assembled under 0.5 T magnetic
field and formed parallel nanobands with about 10 μm long. Assembling two dimensional ordered nanoarrays are still under going.
Received 29 November 2000 相似文献
110.
We argue that supersymmetric transformation could be applied across the heterojunction formed by joining of two mixed semiconductors. A general framework is described by specifying the structure of ladder operators at the junction for making quantitative estimation of physical quantities. For a particular heterojunction device, we show that an exponential grading inside a nanoscale doped layer is amenable to exact analytical treatment for a class of potentials distorted by the junctions through the solutions of transformed Morse-type potentials. 相似文献