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41.
Ahmad Yazdani 《Journal of magnetism and magnetic materials》2009,321(24):3990-3996
In this paper it is demonstrated that the second phase transition of Gd2In intermetallic compound gets eliminated by diluting Gd2−x(LaY)xIn at a critical composition of x=0.5. The exchange coupling for intra-cluster interactions is estimated in the correlation ranges of 3.3 Å<RC<3.6 Å (anisotropic source) and for inter-cluster interactions in the ranges of RC>4 Å where the correlation length is defined as . The sign and strength of the exchange coupling are identified by the eigenvalues λ(k) and are obtained from zeros of the 4×4 matrix of JijRR′ along the three directions of the reciprocal lattice for each dilution (x=0.25, 0.5, 0.75, 1). The transition temperature is calculated using the minimum eigenvalue λmin (k=0, π) which agrees with the experiment. Magnetic field and temperature dependence of the magnetization and electrical resistivity measurements show that: (i) Elimination of the AFM phase is caused by breaking of some FM short-range exchange couplings, and (ii) Conduction electrons order antiferromagnetically at low temperatures and ferromagnetically at high temperatures. 相似文献
42.
43.
Peter Borwein Kwok-Kwong Stephen Choi Soroosh Yazdani 《Proceedings of the American Mathematical Society》2001,129(1):19-27
The Fekete polynomials are defined as
where is the Legendre symbol. These polynomials arise in a number of contexts in analysis and number theory. For example, after cyclic permutation they provide sequences with smallest known norm out of the polynomials with coefficients.
The main purpose of this paper is to prove the following extremal property that characterizes the Fekete polynomials by their size at roots of unity.
Theorem 0.1. Let with odd and . If
then must be an odd prime and is . Here
This result also gives a partial answer to a problem of Harvey Cohn on character sums.
44.
45.
Recent scanning tunneling microscopy experiments of Bi(2)Sr(2)CaCu(2)O(8+delta) have shown evidence of real-space organization of electronic states at low energies in the pseudogap state [Science 303, 1995 (2004)]]. We argue based on symmetry considerations as well as model calculations that the experimentally observed modulations are due to a density wave of d-wave Cooper pairs without global phase coherence. We show that scanning tunneling microscopy measurements can distinguish a pair density wave from more typical electronic modulations such as those due to charge density wave ordering or scattering from an on site periodic potential. 相似文献
46.
Mohammad Joshaghani Davoud Yazdani Ali Akbar Zinatizadeh 《Journal of the Iranian Chemical Society》2017,14(11):2449-2456
Zero-valent iron-modified Degussa P25-TiO2/ZnO nanocomposites (denoted as P25/Fe0/ZnO) were designed and prepared via Fe0 impregnation of P25-TiO2/ZnO and then were employed in the visible-light photocatalytic degradation of p-nitrophenol (PNP) in the presence of [K2S2O8]. Central composite design was applied for response surface modeling (RSM) to understand the influence of selected factors (pH, [Fe0] wt% and [K2S2O8] concentration) on the degradation of PNP and to determine the interaction between the factors. The maximal PNP degradation efficiency (86.9%) was obtained with P25/1.5 wt% Fe0/ZnO at 3 mg/L of [K2S2O8] concentration and pH 7.5. In addition, the RSM showed a satisfactory correlation between the experimental and predicted values of PNP degradation. The P25/Fe0/ZnO photocatalyst performance was also examined degrading methyl orange and phenol and high degradation efficiency, 82 and 99%, was achieved, respectively. The structure, morphology, light absorption and photocatalytic properties of as-prepared P25/Fe0/ZnO were studied using TEM, BET, XRD, FTIR and DRS. 相似文献
47.
The essential oils from aerial parts and fruits of Anisosciadium orientale DC. growing wild in Iran were obtained by hydrodistillation and analyzed by GC and GC/MS. Seventy-one compounds were identified in the fruit oil and fifteen in the oil from the aerial parts. The main oil components of the fruits and aerial parts were myristicin (33.5%-33.7%), alpha-terpinolene (22%-25.8%) and limonene (19.5%-19.7%). Some compounds, such as geranyl butyrate and germacrene-D, were only detected in the fruit oil. 相似文献
48.
Johannes Wallner Esfandiar Nava Yazdani Andreas Weinmann 《Advances in Computational Mathematics》2011,34(2):201-218
After a discussion on definability of invariant subdivision rules we discuss rules for sequential data living in Riemannian
manifolds and in symmetric spaces, having in mind the space of positive definite matrices as a major example. We show that
subdivision rules defined with intrinsic means in Cartan-Hadamard manifolds converge for all input data, which is a much stronger
result than those usually available for manifold subdivision rules. We also show weaker convergence results which are true
in general but apply only to dense enough input data. Finally we discuss C
1 and C
2 smoothness of limit curves. 相似文献
49.
Mehdi Asadi Mostafa Ebrahimi Mohammad Mahdavi Mina Saeedi Parviz Rashidi Ranjbar Farshad Yazdani 《合成通讯》2013,43(17):2385-2392
Heating a mixture of isatoic anhydride, amines, and N,N′-dialkyl carbodiimides under solvent-free conditions provided novel 3-alkyl-2-(alkylamino)quinazolin-4(3H)-one derivatives for the first time. The products were obtained in moderate to good yields without formation of any by-products. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. 相似文献
50.
A. M. Yazdani K. Atazadeh S. Jalalzadeh 《International Journal of Theoretical Physics》2011,50(3):888-898
We study the induced 4-dimensional linearized Einstein field equations in an m-dimensional bulk space by means of a confining potential. We used the confining potential in this model to localized gravitons
on the brane. It is shown that in this approach the mass of graviton is quantized. The cosmological constant problem is also
addressed within the context of this approach. We show that the difference between the values of the cosmological constant
in particle physics and cosmology stems from our measurements in two different scales, small and large. 相似文献