Search for: nanofabrication
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    Design and Fabrication of Electronic Subsystems for NFCVD

    , M.Sc. Thesis Sharif University of Technology Ghaderi, Erfan (Author) ; Rashidian, Bizhan (Supervisor)
    The fabrication of future electronic and optical devices will require advanced nanofabrication techniques that realize high spatial resolution and high precision in controlling size and position, and that are applicable to various materials. Near-field CVD (NF-CVD) was proposed to solve these problems with no need to perform nanolithography prcesses. NFCVD system has two major subsystems, first vacuum chamber and gas distribution system for delivering parent gases to the chamber and second, a nanopositiong system to keep the probe and the sample in the constant systems.In this dissertation we have set up a piezoelectric nanopositiong system and its driver modules. The positioning accuracy... 

    Manufacturing of hydrogel biomaterials with controlled mechanical properties for tissue engineering applications

    , Article Acta Biomaterialia ; Volume 62 , 2017 , Pages 42-63 ; 17427061 (ISSN) Vedadghavami, A ; Minooei, F ; Mohammadi, M. H ; Khetani, S ; Rezaei Kolahchi, A ; Mashayekhan, S ; Sanati Nezhad, A ; Sharif University of Technology
    Hydrogels have been recognized as crucial biomaterials in the field of tissue engineering, regenerative medicine, and drug delivery applications due to their specific characteristics. These biomaterials benefit from retaining a large amount of water, effective mass transfer, similarity to natural tissues and the ability to form different shapes. However, having relatively poor mechanical properties is a limiting factor associated with hydrogel biomaterials. Controlling the biomechanical properties of hydrogels is of paramount importance. In this work, firstly, mechanical characteristics of hydrogels and methods employed for characterizing these properties are explored. Subsequently, the most... 

    Microfluidic systems for stem cell-based neural tissue engineering

    , Article Lab on a Chip - Miniaturisation for Chemistry and Biology ; Volume 16, Issue 14 , 2016 , Pages 2551-2571 ; 14730197 (ISSN) Karimi, M ; Bahrami, S ; Mirshekari, H ; Moosavi Basri, S. M ; Bakhshian Nik, A ; Aref, A. R ; Akbari, M ; Hamblin, M. R ; Sharif University of Technology
    Royal Society of Chemistry  2016
    Neural tissue engineering aims at developing novel approaches for the treatment of diseases of the nervous system, by providing a permissive environment for the growth and differentiation of neural cells. Three-dimensional (3D) cell culture systems provide a closer biomimetic environment, and promote better cell differentiation and improved cell function, than could be achieved by conventional two-dimensional (2D) culture systems. With the recent advances in the discovery and introduction of different types of stem cells for tissue engineering, microfluidic platforms have provided an improved microenvironment for the 3D-culture of stem cells. Microfluidic systems can provide more precise... 

    Rapid formation of hydroxyapatite nanostrips via microwave irradiation

    , Article Journal of Alloys and Compounds ; Volume 469, Issue 1-2 , 2009 , Pages 391-394 ; 09258388 (ISSN) Arami, H ; Mohajerani, M ; Mazloumi, M ; Khalifehzadeh, R ; Lak, A ; Sadrnezhaad, S. K ; Sharif University of Technology
    Hydroxyapatite (HAp) nanostrips were rapidly obtained during a mild microwave heating method. Applying microwave irradiation to Ca(NO3)2·4H2O/CTAB/Na2HPO4 precursor solution, the HAp precipitation process was occurred directly and without common crystallographic transformations including dissolution and slow recrystallization. The cationic surfactant CTAB was used as a soft template to modify nucleation and growth process. TEM investigations showed that the fabricated nanostrips had a width and length of about 10 and 55 nm, respectively. The X-ray diffraction pattern revealed that the fabricated well-crystallized and high purity hydroxyapatite nanostrips had a pattern similar to the bone... 

    Fabrication of granulated NaY zeolite nanoparticles using a new method and study the adsorption properties

    , Article Powder Technology ; Volume 231 , November , 2012 , Pages 1-6 ; 00325910 (ISSN) Charkhi, A ; Kazemeini, M ; Ahmadi, S. J ; Kazemian, H ; Sharif University of Technology
    NaY zeolite nanoparticles were synthesized and shaped into the uniform spherical granules using a developed novel and simple two-step granulation technique. First, the alginate/nanozeolite or alginate/nanozeolite-bentonite spherical hybrid was successfully fabricated, and then the alginate was decomposed by calcinations resulting uniform spherical granules. To improve the mechanical stability of the prepared granules, bentonite was added as an inorganic binder at different ratios of 20wt.% to 40wt.%. Moreover, the effect of binder on the ion exchange properties of the prepared granules was studied. Increasing of binder content from 20wt.% to 40wt.% linearly enhanced the mechanical stability... 

    MOD growth of epitaxial cerium oxide buffer layer on LAO substrates for fabrication of c-axis oriented YBCO

    , Article Micro and Nano Letters ; Volume 7, Issue 10 , 2012 , Pages 1008-1010 ; 17500443 (ISSN) Hosseini, M ; Foroughi Abari, F ; Vesaghi, M. A ; Fardmanesh, M ; Sharif University of Technology
    Epitaxial cerium oxide (CeO2) buffer layer has been grown on lanthanum aluminate (LAO) single crystal substrates for fabrication of c-axis oriented YBa2Cu3O7-x (YBCO). Precursor solution of cerium acetylacetonates with viscosity of 0.6 centipoises was spin coated on the 1×1 cm area LAO substrates. The calcination was carried out by very slow ramp (1°C per minute) until the final temperature of 500°C in oxygen flow to remove most of the organic compounds. The final heat treatment has been done at 780°C by a ramp of 20° per minute in gas flow of mixed argon-oxygen with 5 Pa partial pressure of oxygen. The thickness of the deposited CeO2 buffer layer was 20 nm. Then, 100 nm thick YBCO film was... 

    Hydrothermal synthesis and characterization of TiO 2 nanostructures using LiOH as a solvent

    , Article Advanced Powder Technology ; Volume 22, Issue 3 , 2011 , Pages 336-339 ; 09218831 (ISSN) Zanganeh, S ; Kajbafvala, A ; Zanganeh, N ; Molaei, R ; Bayati, M. R ; Zargar, H. R ; Sadrnezhaad, S. K ; Sharif University of Technology
    In the present study, we performed hydrothermal method as a simple and efficient route for the synthesis of rutile TiO 2 nanostructures in various concentrations of lithium hydroxide solutions. TiO 2 nanopowders with average sizes of 15 and 23 nm were prepared using 4 M and 7 M LiOH solutions. X-ray diffraction analysis (XRD), transmission electron microscope (FEG-STEM), scanning electron microscopy (SEM), and Brunauer-Emmet-Teller (BET) analyses were used in order to characterize the obtained products and comparison of the morphology of the powders obtained in different concentrations of LiOH solvent. It was shown that alkali solution concentration has affected the crystallinity,... 

    Fabrication of porous scaffolds with decellularized cartilage matrix for tissue engineering application

    , Article Biologicals ; Volume 48 , 2017 , Pages 39-46 ; 10451056 (ISSN) Nasiri, B ; Mashayekhan, S ; Sharif University of Technology
    Academic Press  2017
    Due to the avascular nature of articular cartilage, damaged tissue has little capacity for spontaneous healing. Three-dimensional scaffolds have potential for use in tissue engineering approach for cartilage repair. In this study, bovine cartilage tissue was decellularized and chemically crosslinked hybrid chitosan/extracellular matrix (ECM) scaffolds were fabricated with different ECM weight ratios by simple freeze drying method. Various properties of chitosan/ECM scaffolds such as microstructure, mechanical strength, swelling ratio, and biodegradability rate were investigated to confirm improved structural and biological characteristics of chitosan scaffolds in the presence of ECM. The... 

    Permeability mapping of gelatin methacryloyl hydrogels

    , Article Acta Biomaterialia ; Volume 77 , 2018 , Pages 38-47 ; 17427061 (ISSN) Miri, A. K ; Goodarzi Hosseinabadi, H ; Cecen, B ; Hassan, S ; Shrike Zhang, Y ; Sharif University of Technology
    We report the development of an efficient, customized spherical indentation-based testing method to systematically estimate the hydraulic permeability of gelatin methacryloyl (GelMA) hydrogels fabricated in a wide range of mass concentrations and photocrosslinking conditions. Numerical simulations and Biot's theory of poroelasticity were implemented to calibrate our experimental data. We correlated elastic moduli and permeability coefficients with different GelMA concentrations and crosslinking densities. Our model could also predict drug release rates from the GelMA hydrogels and diffusion of biomolecules into the three-dimensional GelMA hydrogels. The results potentially provide a design... 

    Design and fabrication of a two-phase diamond nanoparticle aided fast PCR device

    , Article Analytica Chimica Acta ; Volume 1068 , 2019 , Pages 28-40 ; 00032670 (ISSN) Madadelahi, M ; Ghazimirsaeed, E ; Shamloo, A ; Sharif University of Technology
    Elsevier B.V  2019
    Polymerase Chain Reaction (PCR) is an important and prevalent technique in biotechnology because of its crucial role in cloning DNA fragments and diagnostic applications. In the present study, a high-throughput two-phase PCR device is designed and fabricated which utilizes a serpentine microchannel together with a spiral structure. The former is for the droplet-generation and mixing and the latter is for the thermal cycling process. Moreover, the effect of diamond nanoparticles (diamondNP) on the performance of PCR is also investigated while using commercial PCR devices and the fabricated PCR device designed in this study. Using numerical simulation, it is shown that within the simple and... 

    Stimulus-responsive polymeric nanogels as smart drug delivery systems

    , Article Acta Biomaterialia ; Volume 92 , 2019 , Pages 1-18 ; 17427061 (ISSN) Hajebi, S ; Rabiee, N ; Bagherzadeh, M ; Ahmadi, S ; Rabiee, M ; Roghani Mamaqani, H ; Tahriri, M ; Tayebi, L ; Hamblin, M. R ; Sharif University of Technology
    Acta Materialia Inc  2019
    Nanogels are three-dimensional nanoscale networks formed by physically or chemically cross-linking polymers. Nanogels have been explored as drug delivery systems due to their advantageous properties, such as biocompatibility, high stability, tunable particle size, drug loading capacity, and possible modification of the surface for active targeting by attaching ligands that recognize cognate receptors on the target cells or tissues. Nanogels can be designed to be stimulus responsive, and react to internal or external stimuli such as pH, temperature, light and redox, thus resulting in the controlled release of loaded drugs. This “smart” targeting ability prevents drug accumulation in... 

    A new detection chamber design on centrifugal microfluidic platform to measure hemoglobin of whole blood

    , Article SLAS Technology ; Volume 26, Issue 4 , 2021 , Pages 392-398 ; 24726303 (ISSN) Mahmodi Arjmand, E ; Saadatmand, M ; Eghbal, M ; Bakhtiari, M. R ; Mehraji, S ; Sharif University of Technology
    SAGE Publications Inc  2021
    Undoubtedly, microfluidics has been a focal point of interdisciplinary science during the last two decades, resulting in many developments in this area. Centrifugal microfluidic platforms have good potential for use in point-of-care devices because they take advantage of some intrinsic forces, most notably centrifugal force, which obviates the need to any external driving forces. Herein, we introduce a newly designed detection chamber for use on microfluidic discs that can be employed as an absorbance readout step in cases where the final solution has a very low viscosity and surface tension. In such situations, our chamber easily eliminates the air bubbles from the final solution without... 

    PLGA/TiO2 nanocomposite scaffolds for biomedical applications: Fabrication, photocatalytic, and antibacterial properties

    , Article BioImpacts ; Volume 11, Issue 1 , 2021 , Pages 45-52 ; 22285652 (ISSN) Pelaseyed, S. S ; Madaah Hosseini, H. R ; Nokhbedehghan, Z ; Samadikuchaksaraei, A ; Sharif University of Technology
    Tabriz University of Medical Sciences  2021
    Introduction: Porous 3D scaffolds synthesized using biocompatible and biodegradable materials could provide suitable microenvironment and mechanical support for optimal cell growth and function. The effect of the scaffold porosity on the mechanical properties, as well as the TiO2 nanoparticles addition on the bioactivity, antimicrobial, photocatalytic, and cytotoxicity properties of scaffolds were investigated. Methods: In the present study, porous scaffolds consisting poly (lactide-co-glycolide) (PLGA) containing TiO2 nanoparticles were fabricated via air-liquid foaming technique, which is a novel method and has more advantages due to not using additives for nucleation compared to former... 

    Low-cost air-stable perovskite solar cells by incorporating inorganic materials

    , Article New Journal of Chemistry ; Volume 45, Issue 2 , 2021 , Pages 788-795 ; 11440546 (ISSN) Heshmati, N ; Mohammadi, M. R ; Abachi, P ; Martinez Chapa, S. O ; Sharif University of Technology
    Royal Society of Chemistry  2021
    Herein, we demonstrate a new fabrication strategy for low-cost and stable-operation perovskite solar cells (PSCs) suitable for commercialization. This is performed by fabrication of the device under ambient conditions using a Cs0.05(MA0.17FA0.83)0.95Pb(Br0.17I0.83)3 formulation as the mixed cation and halide (MCH) perovskite and CuInS2 (CIS) as the inorganic hole transporting layer. The deposited MCH perovskite with uniform, compact and smooth microstructure containing equiaxed large grains showed excellent thermal and structural stability under intense conditions at 85 °C for 2 h in humid air (i.e., 45% relative humidity). Moreover, it had higher phosphorescence emission, absorption and... 

    Sonochemical fabrication and catalytic properties of α -Fe2O3 nanoparticles

    , Article Journal of Experimental Nanoscience ; Volume 6, Issue 3 , 2011 , Pages 217-225 ; 17458080 (ISSN) Askarinejad, A ; Bagherzadeh, M ; Morsali, A ; Sharif University of Technology
    In this study, α -Fe2O3 (hematite) nanoparticles were synthesised by a sonochemical method. The influence of different factors such as chemical composition of the precursors, atmosphere of the reactions and type of the sonicator on the chemical formula, crystallinity, morphology and size of the obtained products were investigated. Powder X-ray diffraction, scanning electron microscopy and IR spectroscopy, were used to characterise the nanostructures. The catalytic tests were performed in the reaction of methyl phenyl sulphide oxidation. The results exhibit the good catalytic performance of the as-prepared α -Fe2O3 nanoparticles  

    Fabrication and characterization of conductive chitosan/gelatin-based scaffolds for nerve tissue engineering

    , Article International Journal of Biological Macromolecules ; Volume 74 , 2015 , Pages 360-366 ; 01418130 (ISSN) Baniasadi, H ; Ramazani S. A., A ; Mashayekhan, S ; Sharif University of Technology
    This paper reports on the development of conductive porous scaffolds by incorporating conductive polyaniline/graphene (PAG) nanoparticles into a chitosan/gelatin matrix for its potential application in peripheral nerve regeneration. The effect of PAG content on the various properties of the scaffold is investigated and the results showed that the electrical conductivity and mechanical properties increased proportional to the increase in the PAG loading, while the porosity, swelling ratio and in vitro biodegradability decreased. In addition, the biocompatibility was evaluated by assessing the adhesion and proliferation of Schwann cells on the prepared scaffolds using SEM and MTT assay,... 

    Metal-nonmetal transition in the copper-carbon nanocomposite films

    , Article Physica B: Condensed Matter ; Volume 405, Issue 18 , Jan , 2010 , Pages 3949-3951 ; 09214526 (ISSN) Ghodselahi, T ; Vesaghi, M. A ; Shafiekhani, A ; Ahmadi, M ; Panahandeh, M ; Heidari Saani, M ; Sharif University of Technology
    We prepared Cu nanoparticles in a-C:H thin films by co-deposition of RF-sputtering and RF-PECVD methods at room temperature. By increasing Cu content in these films a nonmetalmetal (NM) transition is observed. This transition is explainable by the power law of percolation theory. The critical metal content is obtained 56% and the critical exponent is obtained 1.6, which is larger than the exponent for 2 dimension systems and smaller than the one for 3 dimension systems. The electrical conductivity of dielectric samples was explained by tunneling. Activation tunneling energy that was obtained from temperature dependence of electrical resistivity correlates with near infrared absorption peak... 

    Heat transfer and entropy generation analysis of hybrid graphene/Fe3O4 ferro-nanofluid flow under the influence of a magnetic field

    , Article Powder Technology ; Volume 308 , 2017 , Pages 149-157 ; 00325910 (ISSN) Mehrali, M ; Sadeghinezhad, E ; Akhiani, A. R ; Tahan Latibari, S ; Metselaar, H. S. C ; Kherbeet, A. S ; Mehrali, M ; Sharif University of Technology
    Elsevier B.V  2017
    The heat transfer characteristics and entropy generation rate of hybrid graphene-magnetite nanofluids under forced laminar flow that subjected to the permanent magnetic fields were investigated. For this purpose, a nanoscale reduced graphene oxide-Fe3O4 hybrid was synthesized by using graphene oxide, iron salts and tannic acid as the reductant and stabilizer. The thermophysical and magnetic properties of the hybrid nanofluid have been widely characterized and thermal conductivity has shown an enhancement of 11%. The experimental results indicated that the heat transfer enhancement of hybrid magnetite nanofluid compared to the case of distilled was negligible when no magnetic field was... 

    Superhydrophobic dual layer functionalized titanium dioxide/polyvinylidene fluoride-co-hexafluoropropylene (TiO2/PH) nanofibrous membrane for high flux membrane distillation

    , Article Journal of Membrane Science ; Volume 537 , 2017 , Pages 140-150 ; 03767388 (ISSN) Seyed Shahabadi, S. M ; Rabiee, H ; Seyedi, S. M ; Mokhtare, A ; Brant, J. A ; Sharif University of Technology
    Elsevier B.V  2017
    In this study, superhydrophobic dual layer membranes with highly porous structure were fabricated using electrospinning and electrospraying techniques. Electrospinning method was used to produce the support nanofibrous layer using polyvinylidene fluoride-co-hexafluoropropylene (PH) as the polymer and a mixed solvent system of N,N-Dimetylformamide (DMF) and acetone. Afterwards, hydrophobic, functionalized TiO2 nanoparticles were deposited on the surface of the support layer using the electrospraying technique. TiO2 chemical functionalization and their deposition on the support layer were investigated by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy. The... 

    Extraction of hydroxyapatite nanostructures from marine wastes for the fabrication of biopolymer-based porous scaffolds

    , Article Marine Drugs ; Volume 18, Issue 1 , 2020 Gheysari, H ; Mohandes, F ; Mazaheri, M ; Dolatyar, B ; Askari, M ; Simchi, A ; Sharif University of Technology
    MDPI AG  2020
    Three-dimensional porous nanocomposites consisting of gelatin-carboxymethylcellulose (CMC) cross-linked by carboxylic acids biopolymers and monophasic hydroxyapatite (HA) nanostructures were fabricated by lyophilization, for soft-bone-tissue engineering. The bioactive ceramic nanostructures were prepared by a novel wet-chemical and low-temperature procedure from marine wastes containing calcium carbonates. The effect of surface-active molecules, including sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (CTAB), on the morphology of HA nanostructures is shown. It is demonstrated that highly bioactive and monophasic HA nanorods with an aspect ratio > 10 can be synthesized in...