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Order parameter effect critical fields and current of Y1–xPrx:123 superconductors

100%

Sedky A. , Amin S. A.

Materials Science Poland

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2017

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tom Vol. 35, No. 4

838--845

EN

Fluctuation induced conductivity by Pr substitution at Y sites of Y1-xPrx:123 superconductors is reported. It is found that the mean field temperature Tcmf, deduced from the peak of dρ/dT versus T plot, gradually decreases by increasing Pr up to 0.40. The order parameter dimensionality (OPD) is estimated from the slope of the logarithmic plot between excess conductivity Δσ and reduced temperature є. Interestingly, the crossover from 2D to 3D is obtained for samples with Pr = 0.00, 0.10 and 0.20, while with increasing Pr up to 0.40, the crossover from 0D to quasi-2D is obtained. On the other hand, the calculated values of interlayer coupling, coherence lengths, critical fields and critical current decrease with increasing Pr up to 0.20, but with the further increase of Pr, up to 0.40, they increase. The hole carriers/Cu ions anisotropy and G-L parameter gradually increase with Pr up to 0.40. Our results are discussed in terms of the effects of Pr substitution at Y site, such as oxygen rearrangements, anisotropy, hybridization and localization of holes in the overdoped region.

2

Effect of temperature on the electrical properties of Zn0.95M0.05O (M = Zn, Fe, Ni)

100%

Sedky A. , Mohamed S. B.

Materials Science Poland

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2014

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tom Vol. 32, No. 1

16--22

EN

We report here the structural and electrical properties of Zn0:95M0:05O ceramic varistors, M = Zn, Ni and Fe. The samples were tested for phase purity and structural morphology by using X-Ray diffraction XRD and scanning electron microscope SEM techniques. The current-voltage characteristics J-E were obtained by dc electrical measurements in the temperature range of 300 – 500 K. Addition of doping did not influence the hexagonal wurtzite structure of ZnO ceramics. Furthermore, the lattice parameters ratio c/a for hexagonal distortion and the length of the bond parallel to the c axis, u were nearly unaffected. The average grain size was decreased from 1.57 μm for ZnO to 1.19 μm for Ni sample and to 1.22 μm for Fe sample. The breakdown field EB was decreased as the temperature increased, in the following order: Fe > Zn > Ni. The nonlinear region was clearly observed for all samples as the temperature increased up to 400 K and completely disappeared with further increase of temperature up to 500 K. The values of nonlinear coefficient, a were between 1.16 and 42 for all samples, in the following order: Fe > Zn > Ni. Moreover, the electrical conductivity s was gradually increased as the temperature increased up to 500 K, in the following order: Ni > Zn > Fe. On the other hand, the activation energies were 0.194 eV, 0.136 and 0.223 eV for all samples, in the following order: Fe, Zn and Ni. These results have been discussed in terms of valence states, magnetic moment and thermo-ionic emission, which were produced by the doping, and controlling the potential barrier of ZnO.

3

Protective potential of quercetin on Cd-induced hepatorenal damage

80%

Sedky A. , Mahboub F. , Elsawy H. , Eid R.

Polish Journal of Environmental Studies

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2017

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tom 26

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nr 5

EN

Industrial and environmental pollution are sources of cadmium (Cd) exposure that cause serious health hazards. In this work we investigated the protective effect of quercetin on Cd-induced hepatorenal damage in rats. Cd toxicity was confirmed by evaluating its level in serum and tissues. Liver function enzymes, bilirubin, albumin, creatinine, uric acid, and urea were assessed in serum. However, lipid peroxidation and the activity of the antioxidant enzymes were examined in tissues. In addition, liver and kidney were studied histologically. Our results showed that the concentration of Cd was higher in tissues of Cd-treated rats while in the Cd and quercetin co-treated group, the Cd concentration was significantly reduced. Co-administration of Cd with quercetin improved the liver function as evident by the reduced levels of ALP, ALT, AST, bilirubin, and the increase in concentration of total protein and albumin. Also, kidney restored its normal function as well as lipid peroxidation, and the antioxidant enzymes partially restored their normal values. In addition, the protective effect of quercetin on the hepatorenal damage induced by Cd was confirmed histologically. In conclusion, quercetin treatment may provide protection against the damages induced by Cd exposure.