Antimicrobial and Photocatalytic Degradation Activities of Chitosan-coated Magnetite Nanocomposite

Journal of Cluster Science - In this work, iron oxide nanoparticles (Fe3O4 NPs) were modified by chitosan (CS). Fe3O4 NPs were synthesized by co-precipitation method and their antimicrobial...     

Physicochemical studies of phosphate based P2O5-Na2O-CaO-TiO2 glasses for biomedical applications

Glasses P₂O₅-Na₂O-CaO-TiO₂ with different TiO₂ contents and fixed P₂O₅ (45 wt%) and CaO (24 wt%) have been prepared employing the normal melting and annealing technique. Measurements such as ultrasonic velocity, attenuation, solubility and pH have been carried out in all the compositions of the glasses. It is interesting to note that the above measured ultrasonic parameters exhibit an abnormal behavior (minimum) at 0.5 wt% of TiO₂ content, beyond which an increase in these parameters with increasing TiO₂ content is observed. The maximum pH values and Ca²⁺ ion release have been observed for the TiO₂ free glass those compositions with and the low TiO₂(?1.0 wt%) content. As the content of the TiO₂ increases, the solubility of the glasses decreases. The observed weight loss reveals two stages of phosphate dissolution kinetics i.e. the first stage, in which the weight loss is proportional to t^1/2, and a second stage in which a linear behavior is observed.     

Leaching of some lithium silicate glasses and glass-ceramics by HCl

The leaching of some binary and ternary lithium silicate glasses and their respective glass-ceramics by HCl is reported.The leaching rate of lithium silicate glasses gradually decreases with the decrease of the percentage of Li₂O or by the introduction of small amounts of a third component, e.g. Al₂O₃, MgO, ZnO or B₂O₃. With a further increase in the proportions of B₂O₃ or ZnO the rate of leaching increases. The rate of leaching is also substantially modified by the conversion of glasses into glasses-ceramics.The results obtained are discussed in terms of the effects of the different ions on the rate of the interdifussion of the lithium and hydrogen ions in the glass and the leached layer, the phase separation developed in the glass, the type and concentration of crystalline phases developed in glass-ceramics and the composition of the residual glass phase.     

Response Surface Methodology Optimization of Melanin Production by <Emphasis Type="Italic">Streptomyces cyaneus</Emphasis> and Synthesis of Copper Oxide Nanoparticles Using Gamma Radiation

Melanin pigment is witnessed to be widely used in medicine, food, cosmetic preparations with strong hydrophobicity. Streptomyces cyaneus is utilized for the synthesis of melanin by optimizing culture conditions through screening of critical factors, by Response Surface Methodology as Plackett–Burman design (P-BD), while further statistical optimization was applied using Central Composite Design (CCD) for maximizing yield. Moreover, the impacts of gamma radiation and alternative frugal l-tyrosine, natural sources were studied as it predicted for remarkable rising in the pigment concentration. Herein unprecedented achievement was realized for melanin pigment production, (9.898 mg/ml) was obtaining by optimized culture condition. Also, 2.0% fava bean’s seed peel maximized melanin (9.953 mg/ml) and hence super-yield (11.113 mg/ml) was produced by a stimulus from gamma irradiation (2.5 kGy). The extracted melanin was confirmed chemically, UV–Vis, and FT-IR analysis. Copper oxide nanoparticles (CuONPs) were synthesized by radiolytic reactions of gamma radiation (30.0 kGy) in the presence of melanin as a capping agent. CuONPs were characterized by UV–Vis, DLS, XRD, and FT-IR. TEM analysis revealed the morphology of monodispersed CuONPs with a mean diameter 29.82 nm. CuONPs exhibited excellent antimicrobial activity against food born Gram-positive, Gram-negative bacteria, and fungi; they can find potential applications for the food packaging approach.     

Electric and dielectric properties of some gamma-irradiated cabal glasses

Electrical conductivity and dielectric properties have been studied for the glass system CaO---B₂O₃---Al₂O₃ in the temperature range 40–200°C. The substitution of 5% B₂O₃ by CaO or replacing 5% CaO by Na₂O or MgO cause a decrease in the conductivity, but the decrease obtained by soda is greater than that of magnesia. The activation energies of the tested glasses were calculated. All the glasses investigated showed a dielectric constant almost independent of temperature at fixed frequency. The effect of subjecting the glass to a constant dose of gamma-rays changes both the electrical conductivity and dielectric constant. The experimental results were discussed in relation to the specific conduction mechanism in such glasses. Also the effect of varying glass composition or temperature on the mobility or migration of current carrier was considered. The possible creation of induced defects in glass on irradiation was evaluated.     

Density and refractive index of some γ-irradiated alkali silicate glasses

The densities and refractive indices of some sodalime-silica glasses with replacements of CaO by either BaO or ZnO have been studied before and after being subjected to varying doses of -irradiation. Also, the effect of varying the Na₂O or Al₂O₃ content was investigated. The experimental results show that -irradiation produces a slight change in the density but a remarkable increase in the refractive index. These data are correlated with the way of housing of the cation introduced into the glass and its response on the compactness and flexibility of the glassy network. Also the effect of interaction of -rays with the glass and the creation of new induced defects in the glass network, which might affect the properties investigated, is considered.