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    Photocatalytic mechanism of action of apatite-coated Ag=AgBr=TiO 2 on phenol and Escherichia coli and Bacillus subtilis bacteria under various conditions

    , Article Progress in Reaction Kinetics and Mechanism ; Volume 36, Issue 1 , February , 2011 , Pages 38-52 ; 14686783 (ISSN) Elahifard, M. R ; Rahimnejad, S ; Pourbaba, R ; Haghighi, S ; Gholami, M. R ; Sharif University of Technology
    2011
    Abstract
    Multi-component photocatalysts based on apatite-coated Ag=AgBr=TiO 2 were prepared by the deposition method. The effects of various kinds of apatites, with hydroxyl and fluoro substituents, on photocatalytic activity were investigated. The antibacterial processes in the dark, and under visible light, on two types of bacteria indicate that the multi-composites can inhibit the growth of bacteria by two different mechanisms. TEM images and optical microscopic data demonstrate that by attaching the nanosize catalyst to the outer membrane of the cell, the bacteria could not derive nourishment from surrounding media, i.e. this component acts as bacteria-static. The mechanism for deactivation of... 

    Stability, size and optical properties of colloidal silver nanoparticles prepared by electrical arc discharge in water

    , Article EPJ Applied Physics ; Volume 48, Issue 1 , 2009 , Pages 10601p1-10601p7 ; 12860042 (ISSN) Ashkarran, A. A ; Iraji Zad, A ; Ahadian, M. M ; Hormozi Nezhad, M. R ; Sharif University of Technology
    2009
    Abstract
    We have fabricated and characterised colloidal silver nanoparticles by the electrical arc discharge method in DI water. Size and optical properties of the silver nanoparticles were studied versus different arc currents. Optical absorption indicates a plasmonic peak at 392 nm for 10 A which increases to 398 nm for 20 A arc current. This reveals that by raising the arc current the size of the nanoparticles increases. Optical absorption of silver nanoparticles after 3 weeks shows precipitation of them in a water medium. The effect of different surfactant and stabilizer concentrations such as cethyl trimethylammonium bromide (CTAB), polyvinyl pyrrolidone (PVP), sodium citrate, sodium dodecyl... 

    Preparation and characterization of nanocrystalline and mesoporous strontium titanate thin films at room temperature

    , Article Journal of Coatings Technology Research ; Volume 8, Issue 5 , July , 2011 , Pages 585-593 ; 15470091 (ISSN) Mohammadi, M. R ; Fray, D. J ; Sharif University of Technology
    2011
    Abstract
    The low temperature perovskite-type strontium titanate (SrTiO 3) thin films and powders with nanocrystalline and mesoporous structure were prepared by a straightforward particulate sol-gel route. The prepared sol had a narrow particle size distribution with hydrodynamic diameter of about 17 nm. X-ray diffraction (XRD) revealed that the synthesized powders had a perovskite-SrTiO 3 structure with preferable orientation growth along the (1 0 0) direction. TEM images showed that the average crystallite size of the powders annealed in the range 300-800°C was around 8 nm. FE-SEM analysis and AFM images revealed that the deposited thin films had mesoporous and nanocrystalline structure with the... 

    The effect of temperature on the TCVD growth of CNTs from LPG over Pd nanoparticles prepared by laser ablation

    , Article Physica B: Condensed Matter ; Volume 405, Issue 16 , 2010 , Pages 3468-3474 ; 09214526 (ISSN) Pasha, M. A ; Poursalehi, R ; Vesaghi, M. A ; Shafiekhani, A ; Sharif University of Technology
    2010
    Abstract
    TCVD growth of multiwalled carbon nanotubes (MWCNTs) was reported by catalytic decomposition of liquefied petroleum gas (LPG) at a temperature range of 580800 °C. Laser ablation was employed as a simple and rapid technique to produce Pd nanoparticles which possess effective catalytic activities for CNT synthesis. UVvisible spectroscopy and TEM images confirmed that the Pd nanoparticles are stable for a long time and have rather spherical shape with average size of 7 nm. SEM and TEM observations and Raman spectroscopy demonstrated that the CNTs have a wavy structure, dense morphology and acceptable crystallinity. Since Pd nanoparticles are inactivated or agglomerated at extremes of the... 

    3D bundles of self-assembled lanthanum hydroxide nanorods via a rapid microwave-assisted route

    , Article Journal of Alloys and Compounds ; Volume 473, Issue 1-2 , 2009 , Pages 283-287 ; 09258388 (ISSN) Mazloumi, M ; Shahcheraghi, N ; Kajbafvala, A ; Zanganeh, S ; Lak, A ; Mohajerani, M. S ; Sadrnezhaad, K ; Sharif University of Technology
    2009
    Abstract
    Three-dimensional (3D) bundles of self-assembled lanthanum hydroxide nanorods with average crystallite size of about 20 nm were fabricated via a facile and rapid microwave-assisted chemical route. The obtained material was characterized with X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations. The obtained nanorods have average diameter of about 115 nm and average length of about 730 nm. Self-assembly of primary La(OH)3 nanoparticles and their subsequent anisotropic growth along 〈2 0 0〉 direction, was proposed to be the mechanism for the formation of 3D bundles of nanorods, using TEM images. The thermal behavior of the... 

    Rapid and efficient synthesis of colloidal gold nanoparticles by arc discharge method

    , Article Applied Physics A: Materials Science and Processing ; Volume 96, Issue 2 , 2009 , Pages 423-428 ; 09478396 (ISSN) Ashkarran, A. A ; Iraji zad, A ; Mahdavi, M ; Ahadian, M. M ; Hormozi nezhad, M. R ; Sharif University of Technology
    2009
    Abstract
    We report a simple, inexpensive and one-step synthesis route of colloidal gold nanoparticles using arc discharge between titanium electrodes in HAuCl 4 solution achieving long-time stability. Gold nanoparticles of 8 nm diameter were formed during reduction of HAuCl4 in the plasma discharge zone. The resulting nanoparticles were characterized using UV-Vis spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Optical absorption spectroscopy of as prepared samples at 15 A arc current in HAuCl4 solution shows a surface plasmon resonance around 550 nm. It was found that sodium citrate acts as a stabilizer and surface capping agent of the colloidal... 

    The effective mechanical properties and the interfacial characterization of CNT reinforced nanocomposites

    , Article Proceedings of SPIE - The International Society for Optical Engineering, 9 March 2009 through 11 March 2009, San Diego, CA ; Volume 7294 , 2009 ; 0277786X (ISSN); 9780819475541 (ISBN) Sadeghia, H ; Naghdabadi, R ; The International Society for Optical Engineering (SPIE) ; Sharif University of Technology
    2009
    Abstract
    A small volume fraction of Carbon Nanotubes (CNTs) added in a polymeric matrix increases significantly the mechanical properties of the polymers. It is experimentally determined from the TEM images of CNT-based nanocomposites that nanotubes don't stand straight in their embedded matrix and they have some curvature in their shape. The load transfer mechanism between CNT and polymer matrix is also one of the most important issues which is not understood explicitly, yet. In this paper a wavy Single Walled Carbon Nanotube (SWCNT) is modeled as inclusion in a polymer matrix and its effective mechanical properties is studied. This model is based on using 3-D Representive Volume Element (RVE) with... 

    Nanocapsules based on carbon nanotubes-graft-polyglycerol hybrid materials

    , Article Nanotechnology ; Volume 20, Issue 48 , 2009 ; 09574484 (ISSN) Adeli, M ; Mirab, N ; Zabihi, F ; Sharif University of Technology
    2009
    Abstract
    In this work the effect of a conjugated macromolecule on the conformation of CNT was studied. Typically polyglycerol (PG) was covalently grafted onto the surface of multi-wall carbon nanotubes (MWCNTs) and MWCNT-graft-PG (MWCNT- g-PG) hybrid materials were obtained. Dynamic light scattering (DLS) experiments showed an average diameter around 100nm for MWCNT- g-PG hybrid materials in water. The difference between this size and the expected size for MWCNT- g-PG hybrid materials (the length of pristine MWCNTs was several micrometers) was assigned to the effect of the grafted PG on the conformation of MWCNT in the solution state. Transmission electron microscopy (TEM) evaluations showed a change...