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151.
The ultrasonic parameters, the optical parameters along with the IR spectroscopy and magnetic susceptibility studies have been employed to explore the role of Gd2O3 in the structure of the glasses xGd2O3–60B2O3–10MoO3–(30-x)Bi2O3, with 0 ≤ x ≤ 7 mol %. IR analysis indicates that Gd2O3 is preferentially incorporated into the borate network-forming BO4 units. It is assumed that Bi2O3 and MoO3 enter the structure as modifiers in the form of BiO6 and MoO6 only. The compositional dependence of the mechanical and the optical parameters are interpreted in terms of the transformation of the structural units BO3 into BO4, the increase in the number of bridging oxygen atoms, and the substitution of high bond strength Gd–O, in the place of low bond strength Bi–O bond. The results of the magnetic susceptibility reveal the paramagnetic behavior as described by the Curie-Weiss law and indicating the presence of weak antiferromagnetic exchange interactions between Gd3+ ions. The magnetic entropy change of the glasses was determined according to the temperature and magnetic field dependence of magnetization. 相似文献
152.
Yasser Khalili Nematollah Kadkhoda Dumitru Baleanu 《Mathematical Methods in the Applied Sciences》2020,43(12):7143-7151
In the present work, we consider the inverse problem for the impulsive Sturm–Liouville equations with eigenparameter-dependent boundary conditions on the whole interval (0,π) from interior spectral data. We prove two uniqueness theorems on the potential q(x) and boundary conditions for the interior inverse problem, and using the Weyl function technique, we show that if coefficients of the first boundary condition, that is, h1,h2, are known, then the potential function q(x) and coefficients of the second boundary condition, that is, H1,H2, are uniquely determined by information about the eigenfunctions at the midpoint of the interval and one spectrum or partial information on the eigenfunctions at some internal points and some of two spectra. 相似文献
153.
Lead vanadate glasses of the system 5Li2O−(45−x) PbO−(50+x) V2O5, with x=0, 5, 10, and 15 mol% have been prepared and studied by differential scanning calorimetry (DSC). The crystallization kinetics of the glasses were investigated under non-isothermal conditions applying the formal theory of transformations for heterogeneous nucleation to the experimental data obtained by DSC using continuous-heating techniques. In addition, from dependence of the glass-transition temperature (Tg) on the heating rate, the activation energy for the glass transition was derived. Similarly the activation energy of the crystallization process was determined and the crystallization mechanism was characterized. The results reveal the increase of the activation energy for glass transition which was attributed to the increase in the rigidity, the cross-link density and the packing density of these glasses. The phases into which the glass crystallizes have been identified by X-ray diffraction. Diffractograms of the transformed material indicate the presence of microcrystallites of Li0.30V2O5, Li0.67O5V2, LiV6O15, Li4O4Pb, and O7Pb2V2 in a remaining amorphous matrix. 相似文献
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In this note we fix a gap in the proof of (7)?(1) of Theorem 4.3 in the paper “Simple-Direct-Modules, Communications in Algebra, Vol. 45 (2017), 3643–3652”. 相似文献
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Mohamed H. M. Abd El-Azim Mohamed G. Assy Mohammed I. Khalil Yasser A. Selim 《Journal of heterocyclic chemistry》2020,57(8):3153-3160
In our study, we aimed to synthesize novel, some biologically active compounds, Azoles and Azines derivatives, that to be nitrogen-containing heterocycles, and have their diverse therapeutic values. Thiosemicarbazide, 2 , was obtained from the attack of nitrogen of hydrazine to the carbon of heteroallene function of compound 1. Triazolotriazole derivative, 4 , was obtained from the reaction of 2 with diethyl malonate. Cyclization of thiourea unit of compound 2 with heteroallene, 1 , gave trazine, 6 . Benzolyation of 2 using benzoyl chloride formed triazole derivative, 8 . Reaction of 2 and maleic anhydride gave furothiadazine, 10. Cyclohexanopyrimidinthione, 12 , was obtained from cyclocondensation of cyclohexanone with 2. Triazole, 14 , was obtained from 2 and ammonium isothiocynate under thermal condition. Reaction of 2 with ethyl bromoacetate gave thiazole derivative, 16. [2+3] Cyclocondensation of acetyl acetone with 2 provided pyrazole, 18 . Triazolotriazole, 20 , was obtained from formalin and 2. Compound 2 suffers intramolecular base mediated cyclization affording pyrazole, 21. Keeping 2 and propinaldehyde under reflux provided triazolotriazole, 24. Acylation of 2 by succinic acid formed pyridazine derivative, 27. 相似文献
160.
Sobhi M. Gomha Amany M. G. Mohamed Yasser H. Zaki Mohamed M. Ewies Shaaban A. Elroby 《Journal of heterocyclic chemistry》2018,55(5):1147-1156
1,3‐Di(thiophen‐2‐yl)prop‐2‐en‐1‐one ( 1 ) was utilized in the synthesis of 4,6‐di(thiophen‐2‐yl)‐3,4‐dihydropyrimidine‐2(1H)‐thione ( 2 ) and 5,7‐di(thiophen‐2‐yl)‐2‐thioxo‐2,3‐dihydropyrido[2,3‐d]pyrimidin‐4(1H)‐one ( 4 ). The latter thiones were used in the synthesis of two new series of [1,2,4]triazolo[4,3‐a]pyrimidines 10a – i and pyrido[2,3‐d][1,2,4]triazolo[4,3‐a]pyrimidinones 5a – i via reaction with the appropriate hydrazonoyl halides using triethylamine as a basic catalyst in dioxane. The mechanism of formation of the synthesized compounds was discussed, and the assigned structure was established via microanalysis, spectral data (infrared, 1H NMR, and Mass), and density functional calculations. Moreover, the newly synthesized products were evaluated for their antimicrobial activities, and the results show that some derivatives have been well with mild activities. Finally, quantum chemistry calculations confirmed the mechanism and structure of the products. 相似文献