Search for: nanostructured-materials
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    Low temperature self-agglomeration of metallic Ag nanoparticles on silica sol-gel thin films

    , Article Journal of Physics D: Applied Physics ; Volume 41, Issue 19 , 2008 ; 00223727 (ISSN) Akhavan, O ; Azimirad, R ; Moshfegh, A. Z ; Sharif University of Technology
    A facile sol-gel synthesis for self-agglomeration of metallic silver nanoparticles, with fcc crystalline structure, on the silica surface in a low annealing temperature has been introduced. X-ray photoelectron spectroscopy (XPS) revealed initial agglomeration (∼30 times greater than the nominal concentration of Ag) of the nanoparticles on the surface of the dried film (100 °C) and also their oxidation as well as easy diffusion (with 0.08 eV required activation energy) into the porous silica thin films, by increasing the annealing temperature (200-400 °C). By raising the Ag concentration from 0.2 to 1.6 mol% in the sol, the average size of the Ag nanoparticles increased from ∼5 to 37 nm... 

    Mechanical induced reaction in Al-CuO system for in-situ fabrication of Al based nanocomposites

    , Article Journal of Alloys and Compounds ; Volume 465, Issue 1-2 , 2008 , Pages 151-156 ; 09258388 (ISSN) Arami, H ; Simchi, A ; Seyed Reihani, S. M ; Sharif University of Technology
    Gradual chemical (displacement) reaction between CuO and Al powders during high-energy attrition milling under a high purity argon atmosphere was studied. Differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques were employed to study the solid-state reaction. It was shown that the solid-state reaction occurred during mechanical alloying (MA) and resulted in the dissolution of copper into the aluminum lattice and formation of nanometric alumina particles. The reinforcement particles were mostly distributed at the grain boundaries of Al matrix with an average crystallite size of about 50 nm. In DTA curve of the milled powders, a small... 

    Synthesis of new hybrid nanomaterials: Promising systems for cancer therapy

    , Article Nanomedicine: Nanotechnology, Biology, and Medicine ; Volume 7, Issue 6 , 2011 , Pages 806-817 ; 15499634 (ISSN) Adeli, M ; Kalantari, M ; Parsamanesh, M ; Sadeghi, E ; Mahmoudi, M ; Sharif University of Technology
    Polyrotaxanes consisting of cyclodextrin rings, polyethylene glycol axes and quantum dot (QD) stoppers were synthesized and characterized. The molecular self-assembly of polyrotaxanes led to spindlelike nano-objects whose shape, size and position were dominated by QD stoppers. Due to their well-defined molecular self-assemblies, carbohydrate backbone, high functionality and several types of functional groups together with the high luminescence yield, synthesized hybrid nanostructures were recognized as promising candidates for biomedical applications. The potential applications of the molecular self-assemblies as drug-delivery systems was investigated by conjugation of doxorubicin (DOX) to... 

    In situ synthesis of nanocrystalline Al6063 matrix nanocomposite powder via reactive mechanical alloying

    , Article Materials Science and Engineering A ; Volume 527, Issue 18-19 , 2010 , Pages 4897-4905 ; 09215093 (ISSN) Asgharzadeh, H ; Simchi, A ; Kim, H. S ; Sharif University of Technology
    In this work, nanocrystalline Al6063 composite powder reinforced with nanometric oxide ceramic particles was synthesized via an in situ solid-gas reaction during high-energy mechanical alloying under a mixture of argon-oxygen atmosphere. The effect of oxygen volume fraction on the morphological evolution and microstructural changes during mechanical alloying was studied by various analytical techniques including optical and electron microscopy, X-ray diffraction, laser particle size analysis, apparent density measurement, and microhardness test. The reactive mechanical alloying resulted in the formation of amorphous Al- and Al-Mg-Si-Fe oxides with a size range of 40-100. nm and volume... 

    Development of nanocrystalline TiO2-Er2O3 and TiO2-Ta2O5 thin film gas sensors: Controlling the physical and sensing properties

    , Article Sensors and Actuators, B: Chemical ; Volume 141, Issue 1 , 2009 , Pages 76-84 ; 09254005 (ISSN) Mohammadi, M. R ; Fray, D. J ; Sharif University of Technology
    A systematic comparison of single and binary metal oxide TiO2, TiO2-Er2O3 and TiO2-Ta2O5 thin film gas sensors with nanocrystalline and mesoporous microstructure, prepared by sol-gel route, was conducted. The gas sensitivity was increased by secondary phase introduction into TiO2 film via two mechanisms, firstly due to the inhibition of anatase-to-rutile transformation, since the anatase phase accommodates larger amounts of adsorbed oxygen, and secondly due to the retardation of grain growth, since the higher surface area provides more active sites for gas molecule adsorption. The binary metal oxide gas sensors exhibited a remarkable response towards low concentrations of CO and NO2 gases at... 

    Nonlinear hierarchical multiscale modeling of cortical bone considering its nanoscale microstructure

    , Article Journal of Biomechanics ; Volume 42, Issue 10 , 2009 , Pages 1560-1565 ; 00219290 (ISSN) Ghanbari, J ; Naghdabadi, R ; Sharif University of Technology
    We have used a hierarchical multiscale modeling scheme for the analysis of cortical bone considering it as a nanocomposite. This scheme consists of definition of two boundary value problems, one for macroscale, and another for microscale. The coupling between these scales is done by using the homogenization technique. At every material point in which the constitutive model is needed, a microscale boundary value problem is defined using a macroscopic kinematical quantity and solved. Using the described scheme, we have studied elastic properties of cortical bone considering its nanoscale microstructural constituents with various mineral volume fractions. Since the microstructure of bone... 

    Optical and electrical properties of the copper-carbon nanocomposites

    , Article Nanophotonics II, Strasbourg, 7 April 2008 through 9 April 2008 ; Volume 6988 , 2008 ; 0277786X (ISSN); 9780819471864 (ISBN) Ghodselahi, T ; Vesaghi, M. A ; Shafiekhani, A ; Ahmadi, M ; Sharif University of Technology
    We prepared copper-carbon nanocomposite films by co-deposition of RF-Sputtering and RF-PECVD methods at room temperature. These films contain different copper concentration and different size of copper nanoparticles. The copper content of these films was obtained from Rutherford Back Scattering (RBS) analyze. We studied electrical resistivity of samples versus copper content. A metal-nonmetal transition was observed by decreasing of copper content in these films. The electrical conductivity of dielectric and metallic samples was explained by tunneling and percolation models respectively. In the percolation threshold conduction results from two mechanisms: percolation and tunneling. In the... 

    Zn-rich (GaN)1−x(ZnO)x: a biomedical friend?

    , Article New Journal of Chemistry ; Volume 45, Issue 8 , 2021 , Pages 4077-4089 ; 11440546 (ISSN) Bagherzadeh, M ; Rabiee, N ; Fatahi, Y ; Dinarvand, R ; Sharif University of Technology
    Royal Society of Chemistry  2021
    A Zn-Rich (GaN)1−x(ZnO)xnanostructure was synthesized with the assistance of a high-gravity technique in order to reduce the reaction time and temperature. The synthesized inorganic nanomaterial has been applied in both drug and gene delivery systems, and as the first fully inorganic nanomaterial, it was investigated in a comprehensive cellular investigation as well. In order to increase the potential bioavailability, as well as the interactions with the pCRISPR, the nanomaterial was enriched with additional Zn ions. The nanomaterial and the final nanocarrier were characterized at each step before and after any biological analysisviaFESEM, AFM, TEM, FTIR and XRD. The polymer coated... 

    Polymer-Coated NH2-UiO-66 for the codelivery of DOX/pCRISPR

    , Article ACS Applied Materials and Interfaces ; Volume 13, Issue 9 , 2021 , Pages 10796-10811 ; 19448244 (ISSN) Rabiee, N ; Bagherzadeh, M ; Heidarian Haris, M ; Ghadiri, A. M ; Matloubi Moghaddam, F ; Fatahi, Y ; Dinarvand, R ; Jarahiyan, A ; Ahmadi, S ; Shokouhimehr, M ; Sharif University of Technology
    American Chemical Society  2021
    Herein, the NH2-UiO-66 metal organic framework (MOF) has been green synthesized with the assistance of high gravity to provide a suitable and safe platform for drug loading. The NH2-UiO-66 MOF was characterized using a field-emission scanning electron microscope, transmission electron microscope (TEM), X-ray diffraction, and zeta potential analysis. Doxorubicin was then encapsulated physically on the porosity of the green MOF. Two different stimulus polymers, p(HEMA) and p(NIPAM), were used as the coating agents of the MOFs. Doxorubicin was loaded onto the polymer-coated MOFs as well, and a drug payload of more than 51% was obtained, which is a record by itself. In the next step, pCRISPR was...