Search for: nanostructured-materials
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    A mathematical method for XRD pattern interpretation in clay containing nano composites

    , Article Applied Surface Science ; Volume 318 , 1 November , 2014 , Pages 90-94 ; ISSN: 01694332 Khederlou, K ; Bagheri, R ; Shojaei, A ; Sharif University of Technology
    X-ray diffraction and rheological measurements were used to characterize nanoparticle dispersion in LDPE/LLDPE/nanoclay hybrid nanocomposites. XRD patterns were interpreted with a novel distribution formula and rheological measurements were used to confirm the results. Results of these two methods indicated that increasing clay in all the prepared nanocomposites exhibited a significant improvement in filler-matrix interaction because of increasing the probability of polymer diffusion but further exfoliation need more compatibilizing situations. It seems that this mathematical method could be used for predicting the overall change in clay gallery d-spacing and the extent of... 

    Nanothickness films, nanostructured films, and nanocrystals of barium titanate obtained directly by a newly developed sol–gel synthesis pathway

    , Article Journal of Materials Science: Materials in Electronics ; Vol. 25, issue. 12 , 2014 , p. 5345-5355 Ashiri, R ; Nemati, A ; Sasani Ghamsari, M ; Dastgahi, M. M ; Sharif University of Technology
    This work aims to develop a chemically modified sol–gel synthesis pathway for obtaining various barium titanate nanostructures. The method is able to prepare different BaTiO3 nanostructures such as highly stable nanoparticle embedded colloids, highly transparent amorphous nanolayers, nanocrystalline BaTiO3 powders and ultrathin BaTiO3 nanostructured films directly from a precursor solution. All the products have been prepared at a lower temperature and in a more cost-effective way in contrast to other established sol–gel methods. The results show that the optical transparency of the thin films has been significantly improved in contrast to the similar researches. The deposited thin film is... 

    Development and biomedical application of nanocomposites: In situ fabrication of ZnO-PbO nanocomposite through microwave method

    , Article Materials Technology ; Vol. 29, issue. 4 , July , 2014 , p. 227-231 Rajabi, A ; Aieneravaie, M ; Dorosti, V ; Sadrnezhaad, S. K ; Sharif University of Technology
    A novel nanocomposite of ZnO-PbO with flower-like nanostructure was fabricated from zinc acetate and lead nitrate as principle raw materials via an in situ process. The novelty of this study consists in the use of a common approach for fabricating of ZnO and PbO nanoparticles simultaneously. From these experiments the conclusion might be drawn that Zn(NH4) 2 4+ ions and Pb(OH)2 act as precursors for the nucleation and growth of ZnO and PbO respectively under microwave irradiation. The precursors formation were carried at two stages: reaction between zinc ions and lead nitrate with ammonium ion and hydroxide sodium respectively. The average crystalline size of Zno and PbO has been analysed by... 

    Hyperthermia-induced protein corona improves the therapeutic effects of zinc ferrite spinel-graphene sheets against cancer

    , Article RSC Advances ; Vol. 4, issue. 107 , 2014 , p. 62557-62565 Hajipour, M. J ; Akhavan, O ; Meidanchi, A ; Laurent, S ; Mahmoudi, M ; Sharif University of Technology
    Superparamagnetic zinc ferrite spinel-graphene nanostructures were synthesized as potential therapeutic agents in the magnetic targeted photothermal therapy of cancer and/or drug delivery. The global temperature of the solution and the local temperature at the nanoparticle (NP) surface determine the protein corona composition/content, which in turn affects the biological effects of NPs and the corresponding physiological responses. Therefore, it is rational to hypothesize that spinel-graphene nanostructures may have distinct protein corona compositions and contents, and therapeutic and toxic effects under laser irradiation. To assess this hypothesis, the effects of laser irradiation on the... 

    Core-shell γ-Fe2O3/SiO2/PCA/Ag-NPs hybrid nanomaterials as a new candidate for future cancer therapy

    , Article International Journal of Nanoscience ; Vol. 13, issue. 1 , February , 2014 Soleyman, R ; Pourjavadi, A ; Masoud, N ; Varamesh, A ; Sharif University of Technology
    In the current study, γ-Fe2O3/SiO 2/PCA/Ag-NPs hybrid nanomaterials were successfully synthesized and characterized. At first, prepared γ-Fe2O3 core nanoparticles were modified by SiO2 layer. Then they were covered by poly citric acid (PCA) via melting esterification method as well. PCA shell acts as an effective linker, and provides vacancies for conveying drugs. Moreover, this shell as an effective capping agent directs synthesis of silver nanoparticles (Ag-NPs) via in situ photo-reduction of silver ions by sunlight-UV irradiation. This system has several benefits as a suitable cancer therapy nanomaterial. Magnetic nanoparticles (MNPs) can guide Ag-NPs and drugs to cancer cells and then... 

    Cross-linked basic nanogel; robust heterogeneous organocalayst

    , Article Chemical Engineering Journal ; Volume 232 , 2013 , Pages 453-457 ; 13858947 (ISSN) Pourjavadi, A ; Hosseini, S. H ; Emami, Z. S ; Sharif University of Technology
    A novel basic poly(ionic liquid) (PIL) was synthesized by miniemulsion polymerization of ionic liquid monomer 1-ethyl-3-vinylimidazolium bromide [EVim][Br] which was cross-linked by ionic liquid cross-linker 1,4-butanediyl-3,3'-bis-l-vinylimidazolium dibromide (BVD). Exchange of bromide anions in PIL nanogel with hydroxide, produced a supported basic ionic liquid catalyst. The catalytic performances of PIL nanogel with a size of about 200. nm was evaluated in the synthesis of 4. H-benzo[. b]pyrans by multi-component reaction in water. The present protocol represents a simple, ecologically safe and cost-effective route to synthesize 4. H-benzo[. b]pyrans with high products yield  

    Hybrid nanomaterials containing PAMAM, polyrotaxane and quantum dot blocks

    , Article Nano ; Volume 6, Issue 3 , June , 2011 , Pages 239-249 ; 17932920 (ISSN) Adeli, M ; Sarabi, R. S ; Sadeghi, E ; Sharif University of Technology
    Pseudopolyrotaxanes, Ps-PR, consisting of α-cyclodextrin rings, polyethylene glycol axes and end triazine groups were prepared and then were capped by amino-functionalized quantum dots, NH 2-QDs, to achieve polyrotaxanes. The amino-functionalized QDs stoppers of polyrotaxanes were used as core to synthesize polyamidoamine, PAMAM, dendrons divergently and hybrid nanomaterials were obtained. Synthesized hybrid nanomaterials were characterized by different spectroscopy, microscopy and thermal analysis methods. They were freely soluble in water and their aqueous solutions were stable at room temperature over several months. Due to their biocompatible backbone, high functionality and water... 

    Influence of autogenous seeding on densification and microstructure in processing of γ-alumina nanopowders

    , Article Phase Transitions ; Volume 84, Issue 1 , 2011 , Pages 1-14 ; 01411594 (ISSN) Khodabakhshi, F ; Maleksaeedi, S ; Paydar, M. H ; Saadat, S ; Sharif University of Technology
    The effect of α-Al 2O 3 seeds and MgO on the densification behavior and microstructure of the nanocrystalline γ-Al 2O 3 powder was investigated. The required α-Al 2O 3 seeds were produced by 'autogenous seeding' where the seeds were obtained by calcination of the initial nanosized γ-Al 2O 3 powders above its transformation temperature and incorporated into γ-Al 2O 3 matrix. The seeds were characterized by means of laser particle size analyzer, X-ray diffraction, and Brunauer-Emmett-Teller surface analyzer. The simultaneous influence of α-Al 2O 3 seeds and MgO on γ-Al 2O 3 behavior was evaluated by differential thermal analysis, densitometry, and electron microscopy. The results showed that... 

    Swelling and mechanical behavior of nanoclay reinforced hydrogel: single network vs. full interpenetrating polymer network

    , Article Polymer Bulletin ; Volume 72, Issue 7 , March , 2015 , Pages 1663-1681 ; 01700839 (ISSN) Kheirabadi, M ; Bagheri, R ; Kabiri, K ; Sharif University of Technology
    Springer Verlag  2015
    Despite the various uses of hydrogels, one of their weaknesses is the poor gel strength. To overcome this restriction, the current study has focused on simultaneously employing an interpenetrating polymer network (IPN) structure and nanocomposite hydrogels. Through this approach, the influence of nanofiller in the single network and IPN hydrogel properties was also studied in detail. For this purpose, a novel full interpenetrating polymer network (IPN) hydrogel nanocomposite based on 2-acrylamido-2-methylpropane sulfonic acid (AMPS)/acrylic acid (AA)–sodium acrylate (AANa) was synthesized in two steps through a facile solution polymerization with incorporation of modified bentonite (MBE) as... 

    Characterization of nanocrystalline CuCo2O4 spinel prepared by sol–gel technique applicable to the SOFC interconnect coating

    , Article Applied Physics A: Materials Science and Processing ; Volume 119, Issue 2 , May , 2015 , Pages 727-734 ; 09478396 (ISSN) Paknahad, P ; Askari, M ; Ghorbanzadeh, M ; Sharif University of Technology
    Springer Verlag  2015
    CuCo2O4 spinel nanopowders were synthesized by sol–gel method. The optimal values of pH and molar ratio of citric acid to metal ions (RC), and the influence of the calcination temperature and time were investigated. As-prepared materials were characterized by XRD, TGA, DSC, FE-SEM and electrical and coefficient of thermal expansion (CTE) measurements. It was found that pH = 4.5 and RC = 1 are the optimum conditions to produce pure CuCo2O4 nanopowders. The electrical conductivity was increased remarkably from 15.2 to 27.5 S cm−1 with an increase in temperature from 500 to 800 °C. Over the temperature range of 25–800 °C, the CTE of... 

    Role of nanoclay distribution on morphology and mechanical behavior of rubber-modified polyolefins

    , Article Journal of Applied Polymer Science ; Volume 132, Issue 20 , 2015 ; 00218995 (ISSN) Babaienejad, M ; Bagheri, R ; Sharif University of Technology
    John Wiley and Sons Inc  2015
    Polyolefin blends have attracted great attention for years because of their improved physical and mechanical properties; especially when micro/nanofillers are present in the compound. Previous investigations have proven that incorporation of small amounts of nanoclay can enhance physical and mechanical properties of the polymer. This research has focused on the role of clay distribution on morphology and mechanical properties of ternary nanocomposites containing a rubbery phase. High-density polyethylene/ethylene vinyl acetate/clay (HDPE/EVA/clay) is opted as a typical model for this purpose. EVA is selected to act as both compatibilizer, because of having polar vinyl groups, and... 

    Synthesis and characterization of electrochemically grown CdSe nanowires with enhanced photoconductivity

    , Article Journal of Materials Science: Materials in Electronics ; Volume 26, Issue 3 , March , 2015 , Pages 1395-1402 ; 09574522 (ISSN) Kalhori, H ; Irajizad, A ; Azarian, A ; Ashiri, R ; Sharif University of Technology
    Springer New York LLC  2015
    CdSe nanowires were grown in polycarbonate track etched membrane with pore diameter of 80 nm by an electrochemical deposition technique. The mechanism of the growth was studied during the potentiostatic deposition of nanowires. X-ray photoelectron spectroscopy and energy dispersive spectrometry results showed binding of fragments and fraction of atoms for the CdSe nanowires. Microstructure and morphology of synthesized CdSe nanowires were observed by scanning electron microscopy. Optical spectrophotometry technique was used to determine the energy band gap of CdSe nanowires. It was found that the nanowires were resistive in the dark and exhibited a pronounced visible light photoconductivity.... 

    Dissipative particle dynamics simulation of electroosmotic flow in nanoscale channels

    , Article 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, Orlando, FL, 4 January 2010 through 7 January 2010 ; 2010 ; 9781600867392 (ISBN) Darbandi, M ; Zakeri, R ; Schneider, G. E ; Sharif University of Technology
    This Paper presents the simulation of electroosmotic flow in nanochannels using the dissipative particle dynamics (DPD) method. Most of the past electroosmotic phenomenon studies have been carried out using the continuum flow assumptions. However, there are many electroosmotic applications in nanoscales NEMS and microscales MEMS, which need to be treated using non-continuum flow assumptions. We simulate the electroosmotic flow within the mesoscopic scale using the DPD method. Contrary to the ordinary molecular dynamics method, the DPD method provides less computational costs. We will show that the current DPD results are in very good agreement with other available non-DPD results. To expand... 

    Reagent-free facile synthesis of silver nanoparticles/nanorods hybrid

    , Article Proceedings of the IASTED International Conference on Nanotechnology and Applications, NANA 2010, 1 November 2010 through 3 November 2010, Cambridge, MA ; 2010 , Pages 498-501 ; 9780889868625 (ISBN) Rezanejade Bardajee, G ; Soleyman, R ; Pourjavadi, A ; Sharif University of Technology
    Silver nanostructures are very important agents in biomedical research, because of its unique activity against unfavorable processes in bioscience. In the current study, reagent-free facile preparation of silver nanoparticles (average diameter: 72 nm) and silver nanoparticles/ nanorods hybrid was reported via wet chemical synthesis method. Kappa-carrageenan (kC), a hydrophilic biopolymer with sulphate groups on its backbone, as capping agent was used in the reaction medium. Silver nanoparticles and silver nanoparticles/ nanorods formation was confirmed by SEM images. Further investigations were carried out using DLS data and GPC analysis  

    Morphology and magnetic properties of FeCo nanocrystalline powder produced by modified mechanochemical procedure

    , Article Journal of Magnetism and Magnetic Materials ; Volume 322, Issue 21 , 2010 , Pages 3551-3554 ; 03048853 (ISSN) Azizi, A ; Sadrnezhaad, S. K ; Hasani, A ; Sharif University of Technology
    Properties of FeCo nanocrystalline intermetallic powders prepared by salt-matrix hydrogen reduction of a milled Fe 2O 3-Co 3O 4 mixture were investigated. The product of 72 ks ball-milling at 350 rpm was CoFe 2O 4 nanopowder. Reduction of this powder for 3.6 ks by hydrogen at 750 °C resulted in the formation of Fe 0.67Co 0.33 stoichiometric compound. Scanning electron microscopy, electron dispersive spectrometry, X-ray diffraction and vibrating sample magnetometry were used to characterize the nanopowder. Using a salt-matrix (NaCl as a dispersion medium) resulted in the decrease of the reduction temperature and improvement of the morphology and magnetic properties of the nanopowder.... 

    Planar molecular dynamics simulation of Au clusters in pushing process

    , Article International Journal of Nanomanufacturing ; Volume 5, Issue 3-4 , 2010 , Pages 288-296 ; 17469392 (ISSN) Mahboobi, S. H ; Meghdari, A ; Jalili, N ; Amiri, F ; Sharif University of Technology
    Based on the fact that the manipulation of fine nanoclusters calls for more precise modelling, the aim of this paper is to conduct an atomistic investigation for interaction analysis of particle-substrate system for pushing and positioning purposes. In the present research, 2D molecular dynamics simulations have been used to investigate such behaviours. Performing the planar simulations can provide a fairly acceptable qualitative tool for our purpose while the computation time is reduced extremely in comparison to 3D simulations. To perform this study, Nose-Hoover dynamics and Sutton-Chen interatomic potential will be used to investigate the behaviour of the aforementioned system. Pushing of... 

    Recent advances in silicon nanowire biosensors: Synthesis methods, properties, and applications

    , Article Nanoscale Research Letters ; Volume 11, Issue 1 , 2016 ; 19317573 (ISSN) Namdari, P ; Daraee, H ; Eatemadi, A ; Sharif University of Technology
    Springer New York LLC 
    The application of silicon nanowire (SiNW) biosensor as a subtle, label-free, and electrical tool has been extensively demonstrated by several researchers over the past few decades. Human ability to delicately fabricate and control its chemical configuration, morphology, and arrangement either separately or in combination with other materials as lead to the development of a nanomaterial with specific and efficient electronic and catalytic properties useful in the fields of biological sciences and renewable energy. This review illuminates on the various synthetic methods of SiNW, with its optical and electrical properties that make them one of the most applicable nanomaterials in the field of... 

    Investigation of the modification process and morphology of organosilane modified nanoclay

    , Article Ceramics - Silikaty ; Volume 53, Issue 4 , 2009 , Pages 254-259 ; 08625468 (ISSN) Khoeini, M ; Bazgir, S ; Tamizifar, M ; Nemati, A. L. I ; Arzani, K ; Sharif University of Technology
    This work deals with the preparation of epoxy-clay nanocomposites. The results show that the mechanical properties of nanocomposites depend on their compatibility, the epoxy resin used and the purity of the nanoclay. The used bentonite was purified and the effects of the organoclay synthesis and various additives on its characteristics were evaluated. X-ray Diffraction (XRD), X-ray Fluorescence (XRF) and Scanning Electron Microscopy (SEM) were used to analyze the microstructure and the phase composition of the nanoclay. The XRD results revealed that when the modifier addition was increased from 10wt.% to 40 wt.%, the interlayer spacing of the nanoclay increased from 12.43 Å being... 

    Rapid biosorption of methylene blue by in situ cellulose-grafted poly 4-hydroxybenzoic acid magnetic nanohybrid: multivariate optimization and isotherm study

    , Article Polymer Bulletin ; 2017 , Pages 1-14 ; 01700839 (ISSN) Alijani, H ; Beyki, M. H ; Kaveh, R ; Fazli, Y ; Sharif University of Technology
    In this research, an efficient biosorption system was developed for methylene blue adsorption over in situ hydrothermally synthesized magnetite 4-hydroxybenzoic acid cellulose nanohybrid. The material was characterized with EDX, VSM, FT-IR, FESEM, and TEM techniques. Results showed that the nanohybrid is a micro-cluster composed of stacked nanoscale particles. Multivariate optimization with Box–Behnken design was used to evaluate effective parameters on adsorption and their interaction. Results showed that pH, shacking time, and adsorbent dosage are effective parameters on MB adsorption. Adsorption rate is fast with equilibrium time of 5.5 min. Isotherm study revealed that the adsorption... 

    Novel aspects of application of cadmium telluride quantum dots nanostructures in radiation oncology

    , Article Applied Physics A: Materials Science and Processing ; Volume 123, Issue 8 , 2017 ; 09478396 (ISSN) Fazaeli, Y ; Zare, H ; Karimi, S ; Rahighi, R ; Feizi, S ; Sharif University of Technology
    Springer Verlag  2017
    In the last two decades, quantum dots nanomaterials have garnered a great deal of scientific interest because of their unique properties. Quantum dots (QDs) are inorganic fluorescent nanocrystals in the size range between 1 and 20 nm. Due to their structural properties, they possess distinctive properties and behave in different way from crystals in macro scale, in many branches of human life. Cadmium telluride quantum dots (CdTe QDs) were labeled with 68Ga radio nuclide for fast in vivo targeting and coincidence imaging of tumors. Using instant paper chromatography, the physicochemical properties of the Cadmium telluride quantum dots labeled with 68Ga NPs (68Ga@ CdTe QDs) were found high...