Nanocrystalline of ZnAl2O4 spinel was synthesized by employing the microwave combustion method.
Different new spinel compositions of formula Zn1-xFexAl2O4, (0.0
x
1.0) were prepared by substitution
of Zn ions with Fe ions. The as-synthesized resultant material ZnAl2O4 with spinel structure as well as
Zn1-xFexAl2O4 compositions were characterized by Energy Dispersive X-ray and X-ray diffraction.
Morphology and particle size evaluation of the nanoparticles were characterized by transmission electron microscopy images. The optical absorption spectra and the magnetization were measured at room
temperature for each Fe ratio. The substitution effect of Fe ions on the optical and magnetic properties of
the original spinel was studied. The optical absorbance showed that the optical band gap decreased with
increasing Fe ratio.

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Background: retinoids are known to be essential for the normal development of diverse embryonic structures including eye. The ventral region of the optic cup of the chick embryo undergoes a complex process of differentiation leading to the formation of different eye structures. Signaling molecules such as retinoic acid (RA) have been implicated in the regulation of these phenomena. Purpose: the present study aims to explore the differential effect of different concentrations of exogenous RA during morphogenesis of the eye of the chick embryo. Materials and methods: fertilized eggs of Gallus domesticus were injected with a single dose of 0.5 µg, 1 µg or 2 µg of RA dissolved in 1 µl od dimethylsulphoxid (DMSO). Injections were carried out after three days of incubation. Results: The excess of exogenous RA caused several malformations in the eye of the embryo. These malformations included disappearance of one eye, bilateral exophthalmos, lens dysgenesis, retinal folds and chorioretinal coloboma. Data of the present study showed highly significant association between the presence of RA and the appearance of deformed eye in embryos. Conclusion: The explanation of these deformities was based on the disturbance of normal pattern of expression of genes concerned with the process of morphogenesis. Where the exogenous RA caused overexpression of some genes resulted in several malformations and disturbance of pattern formation in the eye of the developing embryo.

Background: retinoids are known to be essential for the normal development of diverse embryonic structures including eye. The ventral region of the optic cup of the chick embryo undergoes a complex process of differentiation leading to the formation of different eye structures. Signaling molecules such as retinoic acid (RA) have been implicated in the regulation of these phenomena. Purpose: the present study aims to explore the differential effect of different concentrations of exogenous RA during morphogenesis of the eye of the chick embryo. Materials and methods: fertilized eggs of Gallus domesticus were injected with a single dose of 0.5 µg, 1 µg or 2 µg of RA dissolved in 1 µl od dimethylsulphoxid (DMSO). Injections were carried out after three days of incubation. Results: The excess of exogenous RA caused several malformations in the eye of the embryo. These malformations included disappearance of one eye, bilateral exophthalmos, lens dysgenesis, retinal folds and chorioretinal coloboma. Data of the present study showed highly significant association between the presence of RA and the appearance of deformed eye in embryos. Conclusion: The explanation of these deformities was based on the disturbance of normal pattern of expression of genes concerned with the process of morphogenesis. Where the exogenous RA caused overexpression of some genes resulted in several malformations and disturbance of pattern formation in the eye of the developing embryo.

Background: retinoids are known to be essential for the normal development of diverse embryonic structures including eye. The ventral region of the optic cup of the chick embryo undergoes a complex process of differentiation leading to the formation of different eye structures. Signaling molecules such as retinoic acid (RA) have been implicated in the regulation of these phenomena. Purpose: the present study aims to explore the differential effect of different concentrations of exogenous RA during morphogenesis of the eye of the chick embryo. Materials and methods: fertilized eggs of Gallus domesticus were injected with a single dose of 0.5 µg, 1 µg or 2 µg of RA dissolved in 1 µl od dimethylsulphoxid (DMSO). Injections were carried out after three days of incubation. Results: The excess of exogenous RA caused several malformations in the eye of the embryo. These malformations included disappearance of one eye, bilateral exophthalmos, lens dysgenesis, retinal folds and chorioretinal coloboma. Data of the present study showed highly significant association between the presence of RA and the appearance of deformed eye in embryos. Conclusion: The explanation of these deformities was based on the disturbance of normal pattern of expression of genes concerned with the process of morphogenesis. Where the exogenous RA caused overexpression of some genes resulted in several malformations and disturbance of pattern formation in the eye of the developing embryo.

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