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31.
In this study, the effect of Mg substitution on structural, magnetic and electrical properties of La0.75Sr0.25Mn1?xMgxO3 and La0.75Sr0.25?xMgxMnO3 (nominal compositions) samples are investigated by XRD, Ac susceptibility and electrical resistivity measurements. It is found that Mg does not replace La in the perovskite lattice. Also the results show that by increasing Mg doping levels, the paramagnetic–ferromagnetic and metal–insulator transition temperatures decrease. The reason for decreasing transition temperatures with increasing Mg concentration is, that the long-range FM order has been destroyed by the Mg, which is randomly occupying Mn site. This leads to the suppression of double-exchange interaction in the Mn3+–O–Mn4+ networks. Also the reentrant spin glass (RSG) state accompanied by FM transition, exists in high doped samples. The RSG state could be understood on the basis of double exchange ferromagnetic interaction in Mn3+–O–Mn4+ and super-exchange antiferromagnetic interaction in the Mn4+–O–Mn4+ networks. 相似文献
32.
Mohammad Bagher Majnooni Bahareh Mohammadi Ronak Jalili Gholamreza Bahrami 《液相色谱法及相关技术杂志》2016,39(19-20):877-881
A new high-performance liquid chromatographic method is described for the determination of fatty acids in seed oils. The method was based on precolumn derivatization with 9-fluorenylmethyl chloroformate as a labeling agent and fluorescence detection. Fatty acids were extracted from the samples and subjected to derivatization with the reagent at 60°C for 10?min. The chromatographic separation of 14 fatty acids (C10–C22) was achieved on a combined loading compression octadecyl sulfate (CLC-ODS) column with a run time of 30?min. Three-step gradient elution of a mobile phase consisted of acetonitrile and water was used, and the signal was monitored at excitation and emission wavelengths of 265 and 315?nm, respectively. The method indicated favorable sensitivity and reproducibility for fatty acids’ derivatives. The detection limits, at a signal-to-noise ratio of 3, were 0.01–0.05?µg/ml and relative standard deviations (RSDs) were less than 0.27%. Excellent linear responses were observed with coefficients of 0.9995. This method was applied to quantify fatty acids in white, brown, and black sesame seeds’ oil. 相似文献
33.
We theoretically investigate the energy transfer phenomenon in a double-layer graphene (DLG) system. We use the balance equation approach in linear regime and random phase approximation screening function to obtain energy transfer rates at different electron temperatures, densities and interlayer spacings. We find that the rate of energy transfer in the DLG is qualitatively similar to that obtained in the double-layer two-dimensional electron gas but its values are an order of magnitude greater. Also, at large electron temperature differences between two graphene layers, the electron density dependence of energy transfer is significantly different, particularly in case of unequal electron densities. 相似文献
34.
We investigate theoretically the dependence of energy transfer rate in Double-Quantum-Well system on the well thickness by using the balance equation formalism. Also, by including the local field correction in our calculations through the zero- and finite-temperature Hubbard approximations, we study the effect of the short-range interactions on the energy transfer phenomenon. Calculations consider both the static and dynamic screening approximations. Our numerical results predict that the energy transfer rate increases considerably by increasing the layers' thicknesses and by taking into account the short-range interactions, as well. 相似文献
35.
A series of palladium complexes bearing monodentate and bidentate ligands were applied in the Suzuki reaction of aryl halides and the Heck reaction of styrene with phenylboronic acid. The complexes were found to be effective catalysts for these reactions affording the cross-coupled products in moderate to excellent yields. 相似文献
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Structural Chemistry - In this study, based on new designed and reported molecules with chemical formula of C13H13B2N, novel electrically and optically active oligomers with different size were... 相似文献
40.
Abstract This article presents an all-optical multi-mode interference switch in which the non-linear directional coupler is utilized to realize a passive phase shifter. The proposed structure can be used either as a 1 × 2 or a 2 × 2 switch, with two inputs applied simultaneously in the latter case. The operation of the device is mainly based on the phase difference of the inputs of the multi-mode interference section. The beam propagation method is used for the design and simulation of the structure. The simulation results approve the low sensitivity on wavelength and fabrication tolerances. The crosstalk of the structure is equal to ?31.6 dB. 相似文献