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Jos Vargas Carlos Ramos Roberto D. Zysler Hctor Romero 《Physica B: Condensed Matter》2002,320(1-4):178-180
Chemically prepared (CoxNi1−x)1−yBy (x=0.5, 0.75, 1; y≈0.4) amorphous fine particles were characterized by X-ray diffraction, DTA and TGA, and in situ magnetic measurement as a function of annealing temperature in an inert atmosphere. Magnetic measurement performed in as-prepared and 150°C annealed samples shows an increase of the saturation magnetization and magnetic moment after thermal treatment. Room temperature magnetization increases by factors of 3.5, 1.8, and 1.5, for x=0.5, 0.75, and 1, respectively. These measurements may indicate a local re-ordering of the amorphous phase at temperatures much lower than the full crystallization temperature. 相似文献
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L. Morales A. Caneiro D. VegaR. Zysler H. LanzaR.C. Mercader 《Journal of solid state chemistry》2002,168(1):100-109
The incorporation of Sn into LaMnO3 perovskite and its influence on magnetotransport properties were studied in samples synthesized at low temperature. Single-phase materials for two series of samples with La/(Sn+Mn)=1 and La/(Sn+Mn)<1 ratios were obtained by substitution of up to 10% of the Mn ions by Sn4+. The effect of Sn substitution was monitored through measurements of thermal, “M(T)”, and magnetic field, “M(H)”, dependences of magnetization, as well as of resistivity, “ρ(T)”, at 0 and 70 kOe. These showed that this effect depends strongly on the perovskite cation site ratio (A/B). For La/(Sn+Mn)=1, M and TC were depressed as Sn content was increased. The magnetization data suggest the presence of magnetic clusters with superparamagnetic behavior. No evidence of magnetoresistance (MR) was found. For La/(Sn+Mn)<1 ratio, the samples showed ferromagnetic behavior and MR and both M and TC raised as Sn content increased. The results are discussed in terms of A site vacancies. 相似文献
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The aim of this study was to develop a fast CE separation method by using multiple short-end injections in a capillary coated with quaternary ammonium chitosan (HACC), in order to determine the iodide content of pharmaceutical formulations. The BGE was composed of 20 mM tris(hydroxymethyl)aminomethane and 11 mM hydrochloric acid, at pH 8. The internal standard used was thiocyanate. Separations were performed in a fused silica capillary (32 cm total length, 8.5 cm effective length and 50 μm i.d.) coated with HACC and direct UV detection at 220 nm. EOF was modified by flushing the capillary with polymeric solution, resulting in a semi-permanent coating of controlled and stable EOF. The EOF was anodic at pH 8. Different strategies, using single and multiple injection short-end configurations, were studied to develop a CE method that resulted in a maximum number of iodide samples analyzed per hour: one plug and flush (Sflush) 35 samples/h, one plug without flush (SWflush) 76 samples/h, four plugs and flush (Mflush) 61 samples/h, and four plugs without flush (MWflush) 80 samples/h. Using the multiple injection configuration, it was possible to inject up to four plugs using spacer electrolytes with good separation efficiency and selectivity. The voltage application time needed to separate the eight peaks (iodide and thiocyanate) with MWflush was only 12s. The method was validated and samples were analyzed using MWflush. Good linearity (R(2)>0.999); a limit of detection 0.4 mg L(-1); intermediate precision better than 3.8% (peak area) and recovery in the range of 99-102% were obtained. 相似文献
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We consider four-dimensional variational data assimilation (4DVar) and show that it can be interpreted as Tikhonov or L2-regularisation, a widely used method for solving ill-posed inverse problems. It is known from image restoration and geophysical problems that an alternative regularisation, namely L1-norm regularisation, recovers sharp edges better than L2-norm regularisation. We apply this idea to 4DVar for problems where shocks and model error are present and give two examples which show that L1-norm regularisation performs much better than the standard L2-norm regularisation in 4DVar. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Redondo Mara Julia Romn Lucrecia Rossi Bertone Fiorela Verdecchia Melina 《Algebras and Representation Theory》2022,25(4):1037-1059
Algebras and Representation Theory - Let A and B be two Morita equivalent finite dimensional associative algebras over a field . It is well known that Hochschild cohomology is... 相似文献
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A.?Arhrib R.?BenbrikEmail author Chuan-Hung?Chen Melina?Gomez-Bock Souad?Semlali 《The European Physical Journal C - Particles and Fields》2016,76(6):328
We study the constraints of the generic two-Higgs-doublet model (2HDM) type-III and the impacts of the new Yukawa couplings. For comparisons, we revisit the analysis in the 2HDM type-II. To understand the influence of all involving free parameters and to realize their correlations, we employ a \(\chi \)-square fitting approach by including theoretical and experimental constraints, such as the S, T, and U oblique parameters, the production of standard model Higgs and its decay to \(\gamma \gamma \), \(WW^*/ZZ^*\), \(\tau ^+\tau ^-\), etc. The errors of the analysis are taken at 68, 95.5, and \(99.7~\%\) confidence levels. Due to the new Yukawa couplings being associated with \(\cos (\beta -\alpha )\) and \(\sin (\beta -\alpha )\), we find that the allowed regions for \(\sin \alpha \) and \(\tan \beta \) in the type-III model can be broader when the dictated parameter \(\chi _F\) is positive; however, for negative \(\chi _F\), the limits are stricter than those in the type-II model. By using the constrained parameters, we find that the deviation from the SM in \(h\rightarrow Z\gamma \) can be of \(\mathcal{O}(10~\%)\). Additionally, we also study the top-quark flavor-changing processes induced at the tree level in the type-III model and find that when all current experimental data are considered, we get \(Br(t\rightarrow c(h, H) )< 10^{-3}\) for \(m_h=125.36\) and \(m_H=150\) GeV, and \(Br(t\rightarrow cA)\) slightly exceeds \(10^{-3}\) for \(m_A =130\) GeV. 相似文献
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We report the influence of the Sn doping on the magnetotransport properties of the LaMnO3+δ perovskite. Two series of samples with nominal LaSnxMn1−xO3+δ (I series) and La(1−x)/(1+x)SnxMn1−xO3+δ (II series) compositions (x=0, 0.025, 0.05 and 0.10) were prepared at Ts=750°C. The M(T) data under 0.01 and 0.5 T for the I series reveal a depressed magnetization as the Sn content increases suggesting the presence of magnetic clusters with a superparamagnetic behavior. Resistivity measurements indicate an insulator material for all Sn content independently of the applied magnetic field. On the contrary, for the II series the M(T) and M(H) data reveal FM behavior and an improvement of the magnetization as Sn increases. These samples show magnetoresistance. The magnetotransport properties are discussed in terms of the presence of A-site cation vacancies. 相似文献
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