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71.
Khalid Mujasam Batoo 《Physica B: Condensed Matter》2011,406(3):382-387
The paper reports on the effect of Al substitution on the structural and electrical properties of bulk ferrite series of basic composition MnFe2−2xAl2xO4 (0.0≤x≤0.5) synthesized using solid state reaction method. XRD analysis confirms that all the samples exhibit single phase cubic spinel structure excluding presence of any secondary phase. The dielectric constant shows a normal behaviour with frequency, whereas the loss tangent exhibits an anomalous behaviour with frequency for all compositions. Variation of dielectric properties and ac conductivity with frequency reveals that the dispersion is due to Maxwell-Wagner type of interfacial polarization in general and hopping of charge between Fe+2 and Fe+3 as well as between Mn+2 and Mn+3 ions at octahedral sites. The complex impedance plane spectra shows the presence of two semicircles up to x=0.2, and only one semicircle for the higher values of x. The analysis of the data shows that the resistive and capacitive properties of the Mn ferrite are mainly due to processes associated with grain and grain boundaries. 相似文献
72.
A device for performing vector transmission spectroscopy on aqueous and polar solvent specimens at terahertz frequencies is presented. The device enables the direct measurement of the complex dielectric function across the terahertz band using a Fourier transform IR spectrometer for lossy solutions. Using microfluidic sampling, specimen handling is straightforward and direct measurements on polar specimens are made possible. The method is scalable to longer or shorter wavelengths. 相似文献
73.
74.
The main object of this paper is to present a general mathematical theory applicable to the study of a large class of linear
variational inequalities arising in electronics. Our approach uses recession tools so as to define a new class of problems
that we call “semi-complementarity problems”. Then we show that the study of semi-complementarity problems can be used to
prove new qualitative results applicable to the study of linear variational inequalities of the second kind. 相似文献
75.
Sofian M. Kanan Fatin Samara Imad A. Abu-Yousef Naser Abdo Danial Tobias 《Research on Chemical Intermediates》2010,36(5):473-482
Ag (I) nanoclusters doped in mordenite zeolite were prepared and spectroscopically analyzed. Strong luminescence emission
that is dependent on the excitation wavelength was observed. These variations in the emission modes are due to the site selective
luminescence where various luminophores might be excited upon selecting the proper excitation wavelength. The selected material
was found to have strong affinity to remove the quinalphos pesticide, which is widely used for the protection of several vegetable
and fruit crops, from water bodies. HPLC and GC–MS techniques were used to follow the kinetic data and to identify the photodecomposition
products, respectively. The photodecomposition of quinalphos in the presence of the silver doped mordenite catalyst gives
different products compared to the irradiation of quinalphos without catalyst. The presence of the Ag-mordenite catalyst not
only adsorbs the quinalphos from the solution but it also reduces its toxic effect as tested on the fruit fly (Drosophila melanogaster). 相似文献
76.
77.
This work establishes an asymptotic bound on the characteristic function of signed linear serial rank statistics. The result is obtained under rather general conditions including the important case of van der Waerden scores. It generalizes the result of Seoh (1983, Ph.D. Thesis, Department of Mathematics, Indiana University) and constitutes an essential step to the elaboration of Berry-Esséen's bounds and the establishment of Edgeworth expansions. These statistics constitute a natural tool for testing the hypothesis of white noise with a symmetrical (unspecified) distribution in comparison to other alternative hypothesis of serial dependence. 相似文献
78.
Ralph E. Schlief Wlodzimierz Jarzeba Khalid A. M. Thakur Joseph C. Alfano Alan E. Johnson Paul F. Barbara 《Journal of Molecular Liquids》1994,60(1-3):201-220
Ultrafast pump - probe measurements have been made on the benzene - bromine atom charge transfer (CT) complex in CCl4 and cyclohexane solutions. Ultrafast optical excitation of the CT band of the complex yields an ion pair, which is comprised of a benzene cation and a bromide anion. The rate of charge recombination between the bromide and the benzene cation in the ion pair has been observed to be much faster than the rate of diffusion apart. The charge recombination rate is accelerated at high benzene concentrations as a result of the formation of a benzene dimer cation - bromide ion pair which undergoes much faster charge recombination than the benzene cation - bromide ion pair. 相似文献
79.
Letn be an integer greater than one. Our main result, called the “Structure Theorem” is that a set that containsn−1 disjoint continua that are cut by a single line cannot be ann-point set, that is, a set that meets every line in preciselyn points. This theorem unifies and significantly improves upon a number of known theorems. The second part of the paper is
devoted to several theorems that address the question when a set that meets every line in at mostn points can be extended to ann-point set. These theorems also highlight the sharpness of the Structure Theorem. 相似文献
80.
The magnetic properties of the PrPd2Ge2 and NdPd2Ge2 compounds have been investigated by magnetic measurements, specific heat measurements and neutron diffraction experiments. The PrPd2Ge2 compound orders antiferromagnetically below TN=5.0(2) with an original modulated magnetic structure characterized by a magnetic cell three times larger than the chemical one by tripling of the c parameter. The palladium atom is non magnetic and the Pr moments are parallel to the c-axis with a value of ≈2.0 μB at 2 K. The specific heat measurements clearly detect a low temperature transition for the NdPd2Ge2 compound, interpreted as a Nd sublattice antiferromagnetic ordering below 1.3(2) K. 相似文献