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排序方式: 共有239条查询结果,搜索用时 62 毫秒
1.
Nanosized Fe0.2Ni0.8 particles were prepared by reducing their salts with sodium borohydride (NaBH4) in cationic water-in-oil (w/o) microemulsions of water/cetyl-trimethyl-amonium bromide (CTAB) and n-butanol/isooctane at 25 °C. According to the TEM and X-ray diffraction analyses, the synthesized particles were around 4–12 nm in size. Due to their nanodimensions, the particles had a primitive cubic (pc) structure rather than the body-centered cubic (BCC) structure of the bulk material. An examination of the synthesis from the reverse micelle reveals that the morphology of the iron–nickel alloy nanoparticles depends mainly on the microemulsion's composition. The magnetization of the nanoparticles was much lower than that of the bulk material, reflecting the influence of the nanodimensions on the particles’ magnetizations. 相似文献
2.
C.H Chung S.D KimH.J Kim F.O AdurodijaK.H Yoon J Song 《Solid State Communications》2003,126(4):185-190
The dependence of structural properties and surface morphology of Cu-In alloy layers on the composition and sputtering deposition sequence were investigated by X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The properties of the co-sputtered alloy layers changed abruptly around the composition boundary when the Cu/In ratio reached 1/2. This can be explained by the effective heat of formation (EHF) model, which has been used to predict the sequence of phase formation for metal diffusion couples. The use of a co-sputtered alloy layer with a high In concentration was not suitable for fabricating solar cells, because the film had a very rough morphology due to large In islands formed on the CuIn2 phase. However, it was possible to minimize this phase by In sputtering followed by co-sputtering with a Cu/In ratio of 1 (Cu-In/In/Glass). This permitted the fabrication of a homogeneous Cu-In alloy layer, which was not possible through the simple co-sputtering. 相似文献
3.
A composition spread metal thin film fabrication technique based on ion beam sputter deposition method was developed. The technique enables us to fabricate any desired part or a complete binary/ternary composition spread metal thin films onto a single substrate by sequentially sputtering different target materials. Composition spread metal thin films can be deposited directly on a dielectric film in patterned electrode shape for C-V and I-V measurements. The system could be especially useful in the search for new multi-component metal gate materials. 相似文献
4.
F. Schümann S. Zavatarelli L. Gialanella U. Greife M. Junker D. Rogalla C. Rolfs F. Strieder H.P. Trautvetter 《The European Physical Journal A - Hadrons and Nuclei》1998,2(4):337-342
Abstact: The elastic scattering cross sections, σ (E,θ), for the systems He+Ta and He+W have been measured at θlab=165° and E
lab=76.1 keV to 3.988 MeV using targets with a thickness of a few atomic layers. The results are smaller than the results given
by the Rutherford scattering law, σR(E,θ), due to the effects of electron screening and can be described by σ(E,θ)/σR(E,θ)=(1+Ue/E)−1, where U
e is an atomic screening potential energy. The deduced average value, U
e=28 ± 3 keV, is consistent with the Moliére- and Lenz-Jensen-models as well as electron binding energies.
Received: 25 May 1998 相似文献
5.
R. -H. Rinkleff C. Ruhe F. Thorn 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,27(1):39-43
The optical pumping method with rf detection and the nonlinear level crossing technique were used in parallel electric and magnetic fields to investigate the Stark splitting of all the fine structure levels of the ground multiplet 4f
7 (8
S) 5d6s
2
9
D in Gd I. The tensor polarizabilities were deduced from the level crossing and the rf signals. The variation of the tensor polarizabilities is well reproduced by the LS coupling approximation, except for the small value of the9
D
5 level. A value of the tensor polarizability of the 5d electron is evaluated from the experimental results, 2(5d)=2.00(6) kHz(kV/cm)2. It is shown that the ratio between the electric quadrupole constant and the tensor polarizability is constant, except for the9
D
5 ratio, which is caused by a breakdown of the central field model. 相似文献
6.
The natural radiative lifetime of the 3s4p
1
P
1 level of neutral magnesium was measured by pulsed level-crossing spectroscopy at the short excitation wavelength of 202.6 nm. We obtained =13.4(5) ns for this state, strongly deviating from a previous beam-foil result, but in good agreement with a multi-configuration Hartree-Fock calculation. A discussion of the applicability of the pulsed Hanle effect method is given. 相似文献
7.
We discuss the scale dependence of
s
in connection with jet multiplicities on theZ pole in the framework of perturbative QCD. Several scale defining procedures are applied to jet fractions and compared to recent measurements at LEP.Dedicated to Prof. Dr. H.J. Mang on the occasion of his 60th birthday 相似文献
8.
Cunsolo V Foti S Saletti R Gilbert S Tatham AS Shewry PR 《Journal of mass spectrometry : JMS》2004,39(1):66-78
Structural studies of the high molecular mass (HMM) glutenin subunits 1Bx7 (from cvs Hereward and Galatea) and 1Bx20 (from cv. Bidi17) of bread wheat were conducted using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and reversed-phase high-performance liquid chromatography/electrospray ionization mass spectrometry (RP-HPLC/ESI-MS). For all three proteins, MALDI-TOFMS analysis showed that the isolated fractions contained a second component with a mass about 650 Da lower than the major component. The testing and correction of the gene-derived amino acid sequences of the three proteins were performed by direct MALDI-TOFMS analysis of their tryptic peptide mixture. Analysis of the digest was performed by recording several MALDI mass spectra of the mixture at low, medium and high mass ranges, optimizing the matrix and the acquisition parameters for each mass range. Complementary data were obtained by RP-HPLC/ESI-MS analysis of the tryptic digest. This resulted in coverage of about 98% of the sequences. In contrast to the gene-derived data, the results obtained demonstrate the insertion of the sequence QPGQGQ between Trp716 and Gln717 of subunit 1Bx7 (cv. Galatea) and a possible single amino acid substitution within the T20 peptide of subunit 1Bx20. Moreover, the mass spectrometric data demonstrated that the lower mass components present in all the fractions correspond to the major components but lack about six amino acid residues, which are probably lost from the protein C-terminus. Finally, the results obtained provide evidence for the lack of glycosylation or other post-translational modifications of these subunits. 相似文献
9.
The oscillation property of a gas-vapor cavity near a solid boundary is investigated by a sensitive fiber-optic sensor based on optical beam deflection principle when a high-intensity laser pulse is focused on an aluminum surface in water. The temporal and spatial evolutions of the bubble wall during the expansion and collapse are traced according to sequence waveforms induced by the bubble motion. Both the maximum and minimum bubble radii at each oscillating cycle are determined by experiment. Further, in combination with the spherical bubble theory, the variation of the gas content remaining in the cavity during each pulsation is estimated by the method of fitting curve. The results show that about half of the gas content is dissolved into the surrounding water during the whole process. The less gas content in the cavity makes the bubble contract more violently. The corresponding minimum radius and the collapsing duration become smaller and shorter. 相似文献
10.
The process of growth of an individual cavity in a viscoelastic adhesive layer has been investigated experimentally. The formation
of cavities was caused by the application of a negative pressure on a very confined layer with a flat-ended probe. The cavities
appeared in the bulk of the adhesive layer and were observed for a range of values of applied stress approximately ten times
higher than the shear modulus of the adhesive layer. Depending on the loading rate, the shape of the growing cavity changed
from a flat disc to a more spherical shape. Furthermore, the growth rate of the cavity radius was consistent with a constant
strain rate at the edge of the cavity, which suggests a constant level of stress at the edge of the cavity.
Received 5 June 2002
RID="a"
ID="a"Current address: Ethicon, Johnson & Johnson, Route 22 West, P.O. Box 151, Somerville, NJ 08876-0151, USA.
RID="b"
ID="b"e-mail: costantino.creton@espci.fr 相似文献