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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.

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Thermal analysis of chalcogenide glass similar to other materials is of great importance in order to increase the knowledge about its phase transitions, thermal stability, etc. The current study reports on the thermal kinetics of melt-quenched Zn5Se95 chalcogenide glass using differential thermal analysis (DTA) techniques under non-isothermal conditions. The glass-forming ability (GFA) and the relation between the glass transition and onset crystallization temperatures are found to show a linear behavior. In addition, Moynihan et al. Kissinger’s, and other approaches of Johnson-Mehl-Avrami utilized to determine the activation energy of the amorphous-crystalline and glass transition. It is found that the glass transition process cannot be concluded in terms of single activation energy, and that variation with the extent of conversion was analyzed using various iso-conventional methods. Therefore, the observed change of the activation energy throughout the glass transition reveals that the transition from amorphous to the supercooled liquid phase of Zn5Se95 glass is a complex process. The crystallization process at different heating rates is simulated using the M
alek method, and Sest
akeBerggren SB(M,N) model, in which the SB model show fairly good matching with the experimental DTA data. Moreover; the fragility index is a measure of the GFA of Zn5Se95 chalcogenide glass, which has been estimated using the glass transitions and activation energy values. We have found that the fragility index of Zn5Se95 glass values in between ~13 and 30, depending on the heating rate, revealing that the synthesized glass is a strong liquid with excellent GFA.

The significant use of copper oxide nanoparticles (CuO NPs) has generated worries over their impacts on the ecosystem and human health due to their release from numerous products to the environment. The Solanum nigrum L. is recognized as a phytoremediation plant and may survive within the excessive metal-stressed surroundings. Five CuO NPs levels were evaluated for their impacts on the callus of S. nigrum. Fresh, dry weight, water content, free amino acids, and potassium content of callus cells were significantly decreased due to the impact of CuO NPs. We also observed increased levels of malondialdehyde, bound phenolic compounds, soluble carbohydrates and enzymatic activity of peroxidase, and polyphenol oxidase in callus cells supplying conditions for the lowering of oxidative stress triggered by CuO NPs. Phenylalanine ammonia lyase, soluble proteins and free phenolic compounds in callus cells were increased under 50, 100 and 150 mg/L CuO NPs and were significantly decreased in most cases by the application of the highest concentration (200 mg/L) of CuO NPs. The catalase activity in calli didn’t clearly change via CuO NPs stress. Further, Cu accumulation in the callus was increased with increasing levels of CuO NPs in the medium (50–200 mg/L), as evidenced through 10.3, 17.0, 20.9 and 40.4-fold, respectively, as compared with the control. The FT-IR analysis showed alterations in most macromolecules such as phenolic compounds, lipids, proteins, carbohydrates, cellulose, and hemicellulose in callus cells-treated with CuO NPs. From these results, we can conclude that S. nigrum plants can be used to remediate the medium contaminated with CuO NPs because the plant can accumulate the metal and has a response to defend itself from the metal stress.

This article deals with investigation of fine-scale precipitation in Al-Mg-Zn alloys with compositions of Al - 2 at% Mgx at% Zn, (x = 1.8, 2 and 4.2). The precipitates morphology was examined by scanning electron microscope (SEM) and correlated with the microhardness (HV) and differential scanning calorimetry (DSC) of the specimens. The precipitates are characterized as ’ (MgZn2) and  (MgZn2) phases of hexagonal structure of the same composition with a slight difference in lattice parameters. In addition, T-phase pf composition (Mg32 (Al, Zn)49) having a cubic crystal structure. Owing to the determined activation energies of the precipitates, the kinetics associated with their nucleation and growth can be characterized. The thermal energy acquired during aging leads to the agglomeration of precipitates to or larger particle sizes.

Network of new quaternary borate glasses Bi2O3–Y2O3–Al2O3–B2O3 was studied by FTIR and UV spectroscopies. According to the FTIR results, the addition of Y2O3 increases the amount of bridging oxygens and changes the coordination number of the glasses by creating [BO4] structural units. FTIR investigations explained the increase of the computed elastic moduli according to Makishima–Mackenzie model. The optical parameters such as the UV transmission, the polarizability, and the basicity are found to be sensitive to the concentration of Y2O3. The results of the elastic moduli and the optical parameters were interpreted in terms of the vibrations of structural groups and the strength of the bonds.

This study reports on the optical parameters of MoO3–V2O5–PbO films. The measured transmittance spectra in the spectral range 300–2500 nm was used for precise calculations of the complex index of refraction (real (n) and imaginary (k) parts) as well as the film thicknesses. With the addition of MoO3, a blue shift of the absorption edge was represented while the index of refraction (n) was decreased. The decrease of the index of refraction was discussed in terms of the dispersion model. A good correlation between the bulk modulus Kop, the optical band gap Eg and the index of refraction was observed. With the help of Kop, Eg and n values, the electronic polarizability has been calculated for the films under study. The results well discussed in terms of the density, electronegativity and polarizability changes due to the addition of MoO3 content.

In the present work, Al-Mg-Zn alloys with compositions of Al- 2 at.% Zn — x at.% Mg, (x=1.8, 2, 2.4, 3 and 4.2) have been investigated. The developed precipitates and their growth have been followed as a function of aging temperature. The precipitates morphology was examined by scanning electron microscope (SEM) and correlated with the microhardness (HV) and differential scanning calorimetry (DSC) of the specimens. The structure of the precipitates has been detected by X-ray diffraction (XRD). Mostly, the precipitates are characterized as T′, T, η′ and η phases. The XRD charts analysis show that T′(Mg32 (Al, Zn)49) and T (Mg32 (Al, Zn)49) are cubic whereas η′ (MgZn2) and η (MgZn2) are hexagonal.η′ andrη phases have had a hexagonal structure of the same composition with slight different lattice parameters .