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[en] Abstract Background: Metal oxide clusters are very important inorganic materials, which are widely used in catalytic reactions. And neutron scattering is an important technique for the study of the condensed matters and materials. Purpose: The aim is to study the dynamics of the polymer chain confined in metal oxide cluster molecules. Methods: Quasielastic neutron scattering technique is employed to measure the dynamics of the sample. A theoretical model, which assumes that the vibrational, translational and rotational motions are independent of each other, is used to analyze the neutron spectra. Results: The dynamics of the polymer chain confined in metal oxide cluster are highly restricted in space. The large-scale motion of the chain is greatly hindered. The rotations of the methyl group and methylene group are also slowed down. Conclusion: The metal oxide cluster exhibits ultra-confinement effect on the polymer chains. (authors)
Journal
Nuclear Techniques; ISSN 0253-3219; 
; v. 39(11); [6 p.]
; v. 39(11); [6 p.]
[en] The scattering amplitude of the geometric model is extended to a complex function, which is used to calculate the p-barp scattering at (s)/sup 1/2/ = 540 MeV. The model can fit the shape of the differential cross section and the position of the dip
Journal
[en] For smoothing and shaping the on-target laser patterns flexibly in high-power laser drivers, a scheme has been developed that includes a zoom lens array and two-dimensional smoothing by spectral dispersion (SSD). The size of the target pattern can be controlled handily by adjusting the focal length of the zoom lens array, while the profile of the pattern can be shaped by fine tuning the distance between the target and the focal plane of the principal focusing lens. High-frequency stripes inside the pattern caused by beamlet interference are wiped off by spectral dispersion. Detailed simulations indicate that SSD works somewhat differently for spots of different sizes. For small spots, SSD mainly smooths the intensity modulation of low-to-middle spatial frequency, while for large spots, SSD sweeps the fine speckle structure to reduce nonuniformity of middle-to-high frequency. Spatial spectra of the target patterns are given and their uniformity is evaluated.
Journal
[en] We prepared samples with starting composition Ba8-Ge46-x-Cox (x=0, 4 and 6) by direct melting. These Ge-based compounds were characterized by X-ray diffraction and WDS, and we found two superconducting transitions at TC=10 and 4 K in the Co-free sample. Co-doping results in the suppression of TC to 7 K. The superconducting volume fraction also decreases with increasing Co-doping. For Co-doped samples, there is no 4 K superconducting transition. X-ray refinement shows that the compounds are mixtures of several phases. The dominant phase is diamond Ge, and we found no Ge-clathrate phases. Besides diamond Ge, there are also several weak diffractions from an unknown Ba-Ge phase, and most of them were indexed on the basis of a monoclinic unit cell. Diffraction peaks for Ba2Ge, BaGe, BaGe2, BaGe2O5, BaGeO3, Ba3GeO5, α-BaGeO3, BaGe2O5, Ba2Ge5O12, β-BaGeO3, Ba2GeO4 and BaGe4O9 were carefully searched for but not seen in the samples. For the Co-doped sample, besides the main diamond Ge phase, there is also a semiconducting phase CoGe2. With increasing Co content, the CoGe2 content increases. The WDS results agree with this result. The main phase composition for the Co-free sample is Ba0.01Ge99.9. We also discuss the origin of two superconducting transitions in Ge-based compounds
Journal
[en] Nanocomposites of quaternized and crosslinked poly(4-vinylpyridine) (QC-P4VP) and silver nanoparticles were prepared by a two-step procedure, and characterized by Fourier-transform infrared spectroscopy, Ultraviolet–visible spectroscopy and scanning electron microscopy. Bilayer-structured humidity sensors based on the nanocomposites were fabricated, and the effects of the concentration of silver salt precursor and poly(4-vinylpyridine), the method for the reduction of silver salt, the deposition order of the sensitive layers and environmental temperature on the humidity sensing characteristics of the composite sensor have been examined at room temperature. The composite sensor exhibited low impedance under dry atmosphere due to the introduction of Ag nanoparticles, and could detect very low relative humidity (RH) (down to 1% RH) with good sensitivity (impedance change of 2000% from 1% to 30% RH). In addition, the composite sensor demonstrated very wide measuring range (1–98% RH), and revealed faster response and smaller hysteresis than the sensor based on QC-P4VP alone. The complex impedance spectra of the composite sensor in the environments with different RH levels were investigated to explore its humidity sensing mechanism. - Highlights: • Bilayer-structured nanocomposite of Ag and polyelectrolyte are facilely prepared. • Nanocomposite could measure humidity as low as 1% RH and show small hysteresis. • Nanocomposite is capable of detecting full-range humidity with high sensitivity
Journal
[en] The microstructure and texture evolution of Fe–0.50%Mn non-oriented electrical steel during austenite (γ) to ferrite (α) transformation was studied following various processing conditions. The experimental results demonstrate that the γ→α transformation interface moves from the surface of sheets towards the inner part along the normal direction (ND) under a high temperature gradient in pure hydrogen atmosphere, hereafter calling the process as “directional” phase transformation. Driven by the anisotropic strain energy, the strong {100} textured columnar grains are obtained during the “directional” phase transformation in pure hydrogen atmosphere with a high flow rate. However, driven by the anisotropies of both strain energy and surface energy, the fine {100} and {110} textured columnar grains are developed in pure hydrogen atmosphere with a relatively low flow rate. By contrast, the transformation process is “global” when specimens are annealed in pure nitrogen atmosphere. As a consequence, a {111} texture with equiaxed grains is obtained. In addition, the effect of manganese (Mn) upon the surface oxidation behavior is investigated. - Highlights: • The various atmosphere conditions lead to the microstructure and texture evolution. • The γ→α transformation is “directional” in hydrogen and “global” in nitrogen. • {100} textured columnar grains are obtained at the high flow rate of hydrogen. • {100} and {110} textured columnar grains are obtained at a low flow rate of hydrogen. • A γ-fiber texture with equiaxed grains is obtained in “global” γ→α transformation
Journal
[en] In this paper, the effects of welding speed on the microstructures and mechanical properties of laser welded AZ61 magnesium alloy plates were investigated by microstructural observations, microhardness tests and tensile tests. The results show that the microstructure in the fusion zone consisted of fine α-Mg equiaxed dendrite crystals and dispersed β-Mg17Al12 particles. With an increase in welding speed, the sizes of α-Mg grains and β-Mg17Al12 particles in the fusion zone decreased and the volume fraction of β-Mg17Al12 particles increased. The ultimate tensile strength, yield strength and elongation of welded joint increased when the welding speed increased from 1800 mm min−1 to 2800 mm min−1. In addition, the average hardness value of fusion zone and heat-affected zone increased with the increase in welding speed
Journal
Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing; ISSN 0921-5093; ; CODEN MSAPE3; v. 578; p. 303-309
; CODEN MSAPE3; v. 578; p. 303-309
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