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91.
The effect of substitution of rare earth elements (R) on superconductivity and crystal structure is investigated for the samples
of (La1−xRx)1.82Sr0.18CuO4, R=Pr,Nd,Eu through the measurements of electrical resistivity and lattice parameters. It is revealed thatT
c
suppression due to R-elements is not due to their magnetism but can be attributed to two contributions; the reduction of
the Madelung site potential at apex sites and the random potential scattering on CuO2 plane which in effective for pair-breaking in d-wave superconductors, both of which are brought about by the displacement
of apex oxygens due to the substitution of R-elements. 相似文献
92.
Hye Moon Lee Soon Gil Kim Isao Matsui Toru Iwaki Ferry Iskandar I. Wuled Lenggoro Kikuo Okuyama 《Journal of magnetism and magnetic materials》2007
The deposition monolayers of L10 FePt nanoparticles via an electrospraying method and the magnetic properties of the deposited film were studied. FePt nanoparticles in a size of around 2.5 nm in diameter, prepared by a liquid process, were used as a precursor. The size of the deposited particles can be controlled up to 35 nm by controlling the sprayed droplet size that is formed by adjusting the precursor concentration and the precursor flow rate. The droplets were heated in a tubular furnace at a temperature of up to 900 °C to remove all organic compounds and to transform the FePt particles from disordered face centered cubic to an ordered FCT phase. Finally, the particles were deposited in the form of a monolayer film on a silicon substrate by electrostatic force and characterized by scanning electron microscopy. The monolayer of particles was obtained by the high charge on particles obtained during the electrospraying process. The magnetic properties of the monolayer were investigated by magneto-optic Kerr effect measurements. Coercivity up to 650 Oe for a film consisting of 35 nm L10 FePt nanoparticles was observed after heat treatment at a temperature of 800 °C. 相似文献
93.
Bragg scattering of polaritons by a coherent acoustic wave is mediated and strongly enhanced by the exciton states resonant with the acoustic and optic fields in the intraband and interband transitions, respectively. In this case, in contrast with conventional acousto-optics, the resonantly enhanced Bragg spectra reveal the multiple orders of diffracted light. For polaritons in GaAs microcavities driven by a surface acoustic wave of nu(SAW)=1 GHz and I(ac)< or approximately 100 W/cm(2) the main acoustically induced band gap can be as large as Delta(MC)(ac) approximately equal to 0.6 meV and the Bragg replicas up to n=3 can be observed. 相似文献
94.
Priza Kayestha Anil C. Wijeyewickrema Kikuo Kishimoto 《European Journal of Mechanics - A/Solids》2010,29(2):143-151
The dispersive behaviour of time-harmonic waves propagating along a principal direction in a perfectly bonded pre-stressed compressible elastic bi-material laminate is considered. The dispersion relation which relates wave speed and wavenumber is obtained by formulating the incremental boundary value problem and the use of the propagator matrix technique. At the low wavenumber limit, depending on the pre-stress, both the fundamental mode and the next lowest mode may have finite phase speeds. For the higher modes which have infinite phase speeds in the low wavenumber region, an expression to determine the cut-off frequencies is obtained. At the high wavenumber limit, the phase speeds of the fundamental mode and higher modes tend to phase speeds of the surface wave, the interfacial wave or the limiting phase speed of the composite. For numerical examples, either a two-parameter compressible neo-Hookean material or a two-parameter compressible Varga material is assumed. 相似文献
95.
Jinqiang Li Fengming Li Yuesheng Wang Kikuo Kishimoto 《Acta Mechanica Solida Sinica》2008,21(6):507-516
The wave propagation is studied in two-dimensional disordered piezoelectric phononic crystals using the finite-difference time-domain (FDTD) method. For different cases of disorder, the transmission coefficients are calculated. The influences of disorders on band gaps are investigated. The results show that the disorder in the piezoelectric phononic crystals has more significant influences on the band gap in the low frequency regions than in the high frequency ones. The relation between the width of band gap and the direction of position disorder is also discussed. When the position disorder is along the direction perpendicular to the wave transmission, the piezoelectric phononic crystals have wider band gaps at low frequency regions than the case of position disorder being along the wave transmission direction. It can also be found that the effect of. size disorder on band gaps is analogous to that of location disorder. When the perturbation coefficient is big, it has more pronounced effects on the pass bands in the piezoelectric phononic crystals with both size and location disorders than in the piezoelectric phononic crystals with single disorder. In higher frequency regions the piezoelectric effect reduces the transmission coefficients. But for larger disorder degree, the effects of the piezoelectricity will be reduced. 相似文献
96.
Ataka K Giess F Knoll W Naumann R Haber-Pohlmeier S Richter B Heberle J 《Journal of the American Chemical Society》2004,126(49):16199-16206
A novel concept is introduced for the oriented incorporation of membrane proteins into solid supported lipid bilayers. Recombinant cytochrome c oxidase solubilized in detergent was immobilized on a chemically modified gold surface via the affinity of its histidine-tag to a nickel-chelating nitrilo-triacetic acid (NTA) surface. The oriented protein monolayer was reconstituted into the lipid environment by detergent substitution. The individual steps of the surface modification, including (1) chemical modification of the gold support, (2) adsorption of the protein, and (3) reconstitution of the lipid bilayer, were followed in situ by means of surface-enhanced infrared absorption spectroscopy (SEIRAS) and accompanied by normal-mode analysis. The high surface sensitivity of SEIRAS allows for the identification of each chemical reaction process within the monolayer at the molecular level. Finally, full functionality of the surface-tethered cytochrome c oxidase was demonstrated by cyclic voltammetry after binding of the natural electron donor cytochrome c. 相似文献
97.
The level scheme of the doubly odd nucleus 72As has been investigated by the (p, nγ) reaction up to an excitation energy of about 800 keV. Spin and parity assignments were made by measuring internal conversion coefficients and by an analysis of the (p, n) cross sections through the statistical model of the compound nuclear reaction. The level scheme obtained was interpreted by a simple model calculation based on the shell model. 相似文献
98.
Complete band gaps in two-dimensional piezoelectric phononic crystals with {1–3} connectivity family
Zheng-Hua Qian Feng Jin Feng-Ming Li Kikuo Kishimoto 《International Journal of Solids and Structures》2008,45(17):4748-4755
In this paper, we present results of full band structures for two-dimensional piezoelectric phononic crystals with {1–3} connectivity family. The plane-wave-expansion (PWE) method is applied to the theoretical derivation of secular equations of the two polarization modes: a transverse polarization mode and a mixed (longitudinal-transverse) polarization mode. And the band structures of the two modes for both the case of piezoelectric rods embedded in a polymer matrix and the case of polymer rods embedded in a piezoelectric matrix are calculated for two different cross-sections of the rods, i.e., circular and square, considering the practical fabrication of phononic crystals. We reveal the existence of several very large complete band gaps in a material of practical interest such as PZT rods reinforced polythene composite. The effects of shapes and filling fraction of the rods on band gaps are discussed in detail. The existence of these gaps in relation to the physical parameters of the constituent materials involved is studied. Understanding the band structures of piezoelectric phononic crystals can give some information for improvements in the design of acoustic transducers. 相似文献
99.
Ferry Iskandar Mikrajuddin Abdullah Hiroyoshi Yoden Kikuo Okuyama 《Journal of Sol-Gel Science and Technology》2004,29(1):41-47
Silica films containing three dimensionally (3D) ordered pores were prepared by a simple dip coating method. A colloidal sol containing silica particles in the nanometer size range and a polystyrene latex (PSL) colloidal sol containing particles of tens of nanometers to one micrometer in size were used as precursors. The pore periodicity, which in turn produces the dielectric periodicity, can be easily altered by changing the size of the PSL beads. Films having a high surface smoothness were obtained by using small silica particles, large PSL particles, and a low withdrawal speed in the dip-coating. When the films were irradiated with a white light source, the reflective spectrum was changed by varying the incident angle, indicating its possible use as a monochromator. The change in the reflective spectrum was explained using effective medium approximation combined with a simple Bragg reflection equation. 相似文献
100.
Determination of pesticides in compost by pressurized liquid extraction and gas chromatography-mass spectrometry 总被引:1,自引:0,他引:1
A gas chromatographic-mass spectrometric method was developed for the determination of pesticides in compost. The investigated pesticides included two fungicides, two herbicides and 10 insecticides. The pesticides were extracted from the compost by pressurized liquid extraction. The extract was cleaned up by a partition between hexane and acetonitrile followed by a dispersive solid-phase extraction using a porous carbon made from Moso bamboo (Phyllostachys pubescens). The overall recoveries were 81-104% and the relative standard deviations (RSDs) ranged from 2.4 to 12%. The minimum detectable concentrations were 0.02-0.04 microg g(-1). This method was successfully applied to a compost sample from food waste as well as commercial compost. 相似文献