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Montazeri N.,Islamic Azad University at Tonekabon
International journal of nanomedicine

In this study, calcium phosphate nanoparticles with two phases, fluorapatite (FA; Ca(10)(PO(4))(6)F(2)) and hydroxyapatite (HA; Ca(10)(PO(4))(6)(OH)(2)), were prepared using the solgel method. Ethyl phosphate, hydrated calcium nitrate, and ammonium fluoride were used, respectively, as P, Ca, and F precursors with a Ca:P ratio of 1:72. Powders obtained from the sol-gel process were studied after they were dried at 80°C and heat treated at 550°C. The degree of crystallinity, particle and crystallite size, powder morphology, chemical structure, and phase analysis were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Zetasizer experiments. The results of XRD analysis and FTIR showed the presence of hydroxyapatite and fluorapatite phases. The sizes of the crystallites estimated from XRD patterns using the Scherrer equation and the crystallinity of the hydroxyapatite phase were about 20 nm and 70%, respectively. Transmission electron microscope and SEM images and Zetasizer experiments showed an average size of 100 nm. The in vitro behavior of powder was investigated with mouse fibroblast cells. The results of these experiments indicated that the powders were biocompatible and would not cause toxic reactions. These compounds could be applied for hard-tissue engineering. Source

Montazeri A.,Islamic Azad University at Tonekabon | Chitsazzadeh M.,University of Tehran
Materials and Design

In this study, the effects of duration and output power of sonication on the dispersion state of 0.5wt.% multi-walled carbon nanotube (MWNT) in epoxy matrix were investigated. To disperse the MWNT in the polymer matrix, sonication powers of 25, 50 and 100W and sonication times of 15, 45 and 135min were used. Dynamic mechanical thermal analysis (DMTA) and tensile test were performed under different dispersion states of MWNT. The results indicated that with increase in the sonication time, there was an initial increase in Young's modulus values followed by a drop in values at longer sonication times. The highest Young modulus was gained for the sonication power of 50W and sonication times of 45min. Also the highest tensile strength was obtained for the sonication power of 25W and sonication time of 45min. Also sonication at 50W for 15min was the most effective dispersion for achieving the highest glass transition temperature (Tg). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the dispersion state of MWNT. Well dispersion was observed as the power and duration of sonication were increased. © 2013 Elsevier Ltd. Source

Sadeghi B.,Islamic Azad University at Tonekabon
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

ZnO/Ag nanocomposites coated with polyvinyl chloride (PVC) were prepared by chemical reduction method, for anti-infection biomaterial application. There is a growing interest in attempts in using biomolecular as the templates to grow inorganic nanocomposites in controlled morphology and structure. By optimizing the experiment conditions, we successfully fabricated high yield of ZnO/Ag nanocomposite with full coverage of high-density polyvinyl chloride (PVC) coating. More importantly, ZnO/Ag nanocomposites were shown to significantly inhibit the growth of Staphylococcus aureus in solution. It was further shown that ZnO/Ag nanocomposites induced thiol depletion that caused death of S. aureus. The coatings were fully characterized using techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Most importantly, compared to uncoated metals, the coatings on PVC promoted healthy antibacterial activity. Importantly, compared to ZnO-Ag -uncoated PVC, the ZnO/Ag nanocomposites coated was approximately triplet more effective in preventing bacteria attachment. The result of Thermal Gravimetric Analysis (TGA) indicates that, the ZnO/Ag nanocomposites are chemically stable in the temperature range from 50 to 900 C. This result, for the first time, demonstrates the potential of using ZnO/Ag nanocomposites as a coating material for numerous anti-bacterial applications. © 2013 Elsevier B.V. All rights reserved. Source

Hatamjafari F.,Islamic Azad University at Tonekabon
Oriental Journal of Chemistry

We introduce Cu [(L)proline]2 as a Novel Catalyst, cheap, environmentally friendly, and easy separation for Synthesis of 1, 4-Dihydropyridines under solvent-free condition. IR spectra Confirms formation complex of Cu [(L)proline]2. Source

Vakili B.,Islamic Azad University at Tonekabon
International Journal of Theoretical Physics

We study the canonical formalism of a spherically symmetric space-time. In the context of the 3+1 decomposition with respect to the radial coordinate r, we set up an effective Lagrangian in which a couple of metric functions play the role of independent variables. We show that the resulting r-Hamiltonian yields the correct classical solutions which can be identified with the space-time of a Schwarzschild black hole. The Noether symmetry of the model is then investigated by utilizing the behavior of the corresponding Lagrangian under the infinitesimal generators of the desired symmetry. According to the Noether symmetry approach, we also quantize the model and show that the existence of a Noether symmetry yields a general solution to the Wheeler-DeWitt equation which exhibits a good correlation with the classical regime. We use the resulting wave function in order to (qualitatively) investigate the possibility of the avoidance of classical singularities. © 2011 Springer Science+Business Media, LLC. Source

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