Loading...
Search for: nanoparticles
0.011 seconds
Total 1926 records

    Aggregation and detection of magnetic nanoparticles in microfluidic channels

    , Article Journal of Electrical Engineering ; Volume 63, Issue 7 SUPPL , 2012 , Pages 27-30 ; 13353632 (ISSN) Sarreshtedari, F ; Kokabi, H ; Gamby, J ; Ngo, K. A ; Krause, H. J ; Fardmanesh, M ; Sharif University of Technology
    2012
    Abstract
    Incorporating numerical simulation with COMSOL Multiphysics, the aggregation and detection of superparamagnetic nanoparticles in microfluidic channels are investigated. Considering the physical specifications of the implemented microchannels, the parameters which determine the ability of the system for aggregation and detection of the particles are examined and simulated. Based on the simulation results, we propose a new approach for both capturing and detecting of the magnetic nanoparticles passing through microchannels  

    A new colloidal technique for the synthesis of lead sulfide nanoparticles

    , Article Scientia Iranica ; Volume 10, Issue 3 , 2003 , Pages 357-360 ; 10263098 (ISSN) Askari, M ; Ghamsari, M. S ; Sharif University of Technology
    Sharif University of Technology  2003
    Abstract
    In this paper, the use of colloid chemistry in the synthesis of 5 A° lead sulfide semiconductor nanoparticles has been described. Here, hydrogen sulfide gas dissolved in water is used for the chemical reaction, instead of purging the H2S gas into the solution, which has an influence on particle size. In this technique, the growth of particles was controlled by the addition of EDTA. A fast evolution of the optical absorption spectrum demonstrated the following synthesis. Soon after synthesis reaction, the sample exhibits a structural absorption spectrum with one well-defined peak in a 240 nm wavelength. The absorption spectrum shows a featureless structure, with no tail near the absorption... 

    Spectrophotometric and Colorimetric Determination of 4-Hydroxy-2 -Mercapto-6-Methylpyrimidine (MTU) Based on the Aggregation of Gold Nanoparticles

    , M.Sc. Thesis Sharif University of Technology Ghayyem, Sana (Author) ; Hormozinezhad, Mohammad Reza (Supervisor)
    Abstract
    4-Hydroxy-2-mercapto-6-methylpyrimidine (MTU), is a drug from thiouracil antithyroid family which inhibits thyroid hormone synthesis and is generally used to remedy hyperthyroidism in gestation and liver disease. On the other hand, MTU has been applied to animals to gain higher weight . Since remaining of thyreostatic drugs in eatable animal tissues could be a risk to human health, their use in animal products was prohibited in the European Union in 1981.Based on these reasons, the need for an analytical procedure capable of determining MTU is of great importance. We report herein the development of a highly sensitive colorimetric method for the detection of MTU utilizing citrate capped gold... 

    Electrodeposition of Copper Oxide Nanoparticles on Precasted Carbon Nanoparticles Film for Electrochemical Investigation of anti-HIV Drug Nevirapine

    , Article Electroanalysis ; Volume 27, Issue 8 , June , 2015 , Pages 1989-1997 ; 10400397 (ISSN) Shahrokhian, S ; Kohansal, R ; Ghalkhani, M ; Amini, M. K ; Sharif University of Technology
    Wiley-VCH Verlag  2015
    Abstract
    This work describes the development of a novel electrochemical sensor based on electrodeposition of copper oxide nanoparticles onto carbon nanoparticle (CNP) film modified electrode for the analysis of the anti-HIV drug, nevirapine (NEV). The electrochemical experiments were performed using linear sweep and cyclic voltammetry. Atomic force microscopy was applied for surface characterization of the deposited modifier film (CuO-CNP) on glassy carbon electrode (GCE). No oxidation peak was observed for NEV on the bare GCE, but both CNP-GCE and CuO-CNP-GCE showed a distinctive anodic response towards NEV with considerable enhancement (276-fold and 350-fold, respectively) compared to CuO-GCE. The... 

    Avrami behavior of magnetite nanoparticles formation in co-precipitation process

    , Article Journal of Mining and Metallurgy, Section B: Metallurgy ; Volume 47, Issue 2 , 2011 , Pages 211-218 ; 14505339 (ISSN) Ahmadi, R ; Hosseini, H. M. R ; Masoudi, A ; Sharif University of Technology
    Abstract
    In this work, magnetite nanoparticles (mean particle size about 20 nm) were synthesized via coprecipitation method. In order to investigate the kinetics of nanoparticle formation, variation in the amount of reactants within the process was measured using pH-meter and atomic absorption spectroscopy (AAS) instruments. Results show that nanoparticle formation behavior can be described by Avrami equations. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were performed to study the chemical and morphological characterization of nanoparticles. Some simplifying assumptions were employed for estimating the nucleation and growth rate of magnetite nanoparticles  

    Sol-gel synthesis of thermoluminescent Cd-doped ZnTe nanoparticles

    , Article Indian Journal of Pure and Applied Physics ; Volume 53, Issue 12 , 2015 , Pages 804-807 ; 00195596 (ISSN) Shafiee, S ; Akhavan, O ; Hatami, H ; Hoseinkhani, P ; Sharif University of Technology
    National Institute of Science Communication and Information Resources (NISCAIR)  2015
    Abstract
    The Cd (3 wt%)-doped ZnTe nanoparticles with average size of 5 nm and band gap energy of 3.15 eV were synthesized by sol-gel method. The optical properties (such as band gap energy) and the size distribution of the nanoparticles have been investigated by using UV-Vis spectroscopy and transmission electron microscopy, respectively. Then, thermoluminescence property of the nanoparticles exposed to various doses of gamma radiation of Cs137 has been studied. The thermoluminescence glow peak of the nanoparticles showed a displacement from 290 to 230°C by increasing the dose of gamma radiation from 7.5 to 67.5 mSv. The thermoluminescence intensity of the synthesized Cd-doped ZnTe nanoparticles... 

    Synthesis, structural characterization and reactivity of manganese tungstate nanoparticles in the oxidative degradation of methylene blue

    , Article Comptes Rendus Chimie ; Volume 18, Issue 2 , 2015 , Pages 199-203 ; 16310748 (ISSN) Khaksar, M ; Boghaei, D. M ; Amini, M ; Sharif University of Technology
    Elsevier Masson SAS  2015
    Abstract
    Nanoparticles of manganese tungstate (MnWO4) were prepared via an impregnation method using Mn(NO3)2 4H2O and WO3 as a source of Mn and W, respectively. The morphology of the manganese tungstate nanoparticles was studied in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). MnWO4 nanoparticles showed severe catalytic performances for the degradation of organic dye (methylene blue, MB) in the presence of tert-butyl hydrogen peroxide, TBHP, as the oxidant at room temperature in water  

    Understanding the nanoparticle-protein corona complexes using computational and experimental methods

    , Article International Journal of Biochemistry and Cell Biology ; Volume 75 , 2016 , Pages 162-174 ; 13572725 (ISSN) Kharazian, B ; Hadipour, N. L ; Ejtehadi, M. R ; Sharif University of Technology
    Elsevier Ltd 
    Abstract
    Nanoparticles (NP) have capability to adsorb proteins from biological fluids and form protein layer, which is called protein corona. As the cell sees corona coated NPs, the protein corona can dictate biological response to NPs. The composition of protein corona is varied by physicochemical properties of NPs including size, shape, surface chemistry. Processing of protein adsorption is dynamic phenomena; to that end, a protein may desorb or leave a surface vacancy that is rapidly filled by another protein and cause changes in the corona composition mainly by the Vroman effect. In this review, we discuss the interaction between NP and proteins and the available techniques for identification of... 

    A modified Jarzynski free-energy estimator to eliminate non-conservative forces and its application in nanoparticle-membrane interactions

    , Article Physical Chemistry Chemical Physics ; Volume 24, Issue 6 , 2022 , Pages 3647-3654 ; 14639076 (ISSN) Hosseini, A. N ; Lund, M ; Ejtehadi, M. R ; Sharif University of Technology
    Royal Society of Chemistry  2022
    Abstract
    Computational methods to understand interactions in bio-complex systems are however limited to time-scales typically much shorter than in Nature. For example, on the nanoscale level, interactions between nanoparticles (NPs)/molecules/peptides and membranes are central in complex biomolecular processes such as membrane-coated NPs or cellular uptake. This can be remedied by the application of e.g. Jarzynski's equality where thermodynamic properties are extracted from non-equilibrium simulations. Although, the out of equilibrium work leads to non-conservative forces. We here propose a correction Pair Forces method, that removes these forces. Our proposed method is based on the calculation of... 

    Microstructure and compressibility of SiC nanoparticles reinforced Cu nanocomposite powders processed by high energy mechanical milling [electronic resource]

    , Article Ceramics International ; Volume 40, Issue 1, Part A, January 2014, Pages 951–960 Akbarpour, M.R. (Mohammad Reza) ; Salahi, E ; Alikhani Hesari, F ; Simchi, A ; Kim, H. S ; Sharif University of Technology
    Abstract
    Cu/SiC nanocomposite powders with homogeneously distributed nanosize SiC particles were produced by high energy mechanical milling (MM). Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and micro-hardness and density measurements were performed to understand the effects of microstructure and hardness on compaction behavior during MM. The effects of SiC nanoparticle content and mechanical milling time on apparent density (AD) and tap density (TD) of the nanocomposite powders were systematically investigated. The Hausner ratio (HR), defined as TD to AD, were estimated to evaluate friction between the particles. Increasing MM duration and SiC content resulted... 

    A new approach for the in vitro identification of the cytotoxicity of superparamagnetic iron oxide nanoparticles

    , Article Colloids and Surfaces B: Biointerfaces ; Volume 75, Issue 1 , 1 January , 2010 , Pages 300–309 Mahmoudi, M. (Morteza) ; Simchi, A. (Abdolreza) ; Imani, M. (Mohammad) ; Shokrgozar, M. A. (Mohammad A.) ; Milani, A. S. (Abbas S.) ; Hafeli, Urs O ; Stroeve, Pieter ; Sharif University of Technology
    Abstract
    Superparamagnetic iron oxide nanoparticles (SPIONs) are increasingly used in medical applications, such as targeting delivery and imaging. In the future, patients are more likely to be exposed to pharmaceutical products containing such particles. The study of toxicity of SPIONs has become of great importance in recent years, although the published data in this arena is limited. The aim of the present work is to investigate the cytotoxicity of SPIONs and the effect of the particles on the cell medium components. For this purpose, uncoated and polyvinyl alcohol (PVA) coated SPIONs with narrow size distribution were synthesized via a well-known coprecipitation method. The mouse fibroblast cell... 

    A new approach for calculation of relaxation time and magnetic anisotropy of ferrofluids containing superparmagnetic nanoparticles

    , Article Journal of Mining and Metallurgy, Section B: Metallurgy ; Volume 48, Issue 1 , 2012 , Pages 81-88 ; 14505339 (ISSN) Ahmadi, R ; Hosseini, H. R. M ; Sharif University of Technology
    2012
    Abstract
    In this work, a new approach is described for the calculation of the relaxation time and magnetic anisotropy energy of magnetic nanoparticles. Ferrofluids containing monodispersed magnetite nanoparticles were synthesized via hydrothermal method and then heated using the 10 kA/m external AC magnetic fields in three different frequencies: 10, 50 and 100 kHz. By measuring the temperature variations during the application of the magnetic field, the total magnetic time constant including both Brownian and Neel relaxation times can be calculated. By measuring the magnetic core size and hydrodynamic size of particles, the magnetic anisotropy can be calculated too. Synthesized ferrofluids were... 

    Controlled crystallization of LTA zeolitic nanoparticles from a clear solution using organic template

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 30, Issue 2 , 2011 , Pages 9-14 ; 10219986 (ISSN) Esmaeili, N ; Kazemian, H ; Bastani, D ; Sharif University of Technology
    2011
    Abstract
    LTA Zeolite nanoparticles was successfully synthesized from clear solution under controlled conditions using hydrothermal method using tetramethyl ammonium hydroxide as a structural directing agent. The as-synthesized LTA zeolite particles were characterized by powder X-ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), Fourier Transform InfraRed (FT-IR) spectroscopy, Energy Dispersive X-ray (EDX) analysis and surface area measuring technique of Brunauer, Emmett and Teller (BET). XRD patterns and FT-IR spectra were ascertained the formation of pure crystalline phase of 4A (i.e. LTA) zeolite. SEM micrograph was shown particles size in the range of 60 -170 nm with uniform... 

    Nanocellulose/Carbon Nanoparticles Nanocomposite Film Modified Electrode for Durable and Sensitive Electrochemical Determination of Metoclopramide

    , Article Electroanalysis ; Volume 27, Issue 11 , November , 2015 , Pages 2637-2644 ; 10400397 (ISSN) Shahrokhian, S ; Naderi, L ; Ghalkhani, M ; Sharif University of Technology
    Wiley-VCH Verlag  2015
    Abstract
    A novel electrochemical sensor based on nanocellulose-carbon nanoparticles (NC-CNPs) nanocomposite film modified glassy carbon electrode (GCE) is developed for the analysis of metoclopramide (MCP). Atomic force microscopy, scanning electron microscopy and electrochemical impedance spectroscopy were used to characterize the roughness, surface morphology and performance of the deposited modifier film on GCE. SEM image demonstrated that modifier nanoparticles are uniformly deposited on GCE, with an average size of less than 50nm. The electrochemical behavior of MCP and its oxidation product is studied using linear sweep and cyclic voltammetry over a wide pH range on NC-CNPs modified glassy... 

    A Visual Colorimetric Probe for Naked-Eye Detection of Pamidronate Disodium in Human Plasma Based on Aggregation of Citrate-Capped Gold Nanoparticles

    , Article Plasmonics ; Volume 10, Issue 4 , 2015 , Pages 971-978 ; 15571955 (ISSN) Hormozi Nezhad, M. R ; Abbasi-Moayed, S ; Sharif University of Technology
    Springer New York LLC  2015
    Abstract
    Herein, a sensitive, simple, and rapid colorimetric assay for the detection of pamidronate disodium was developed based on the aggregation of citrate-capped gold nanoparticles (AuNPs). This was exploited from the affinity of electron-rich atoms toward the surface of AuNPs, resulting in the aggregation of AuNPs through intermolecular hydrogen bonding interactions. As a result of aggregation under optimum conditions ([NaCl] = 25 mM, [AuNPs] = 3.3 nM and pH 7.0), the color of AuNPs was changed from red to blue and the plasmon band of AuNPs around 520 was decreased along with the formation of a new peak at a longer wavelength in the approximate range of 600 to 700 nm. The intensity ratios of... 

    Experimental and numerical investigation of fully developed forced convection of water-based Fe3O4 nanofluid passing through a tube in the presence of an alternating magnetic field

    , Article Advances in Mechanical Engineering ; Volume 7, Issue 2 , February , 2015 , Pages 1-9 ; 16878132 (ISSN) Dibaei Bonab, M. H ; Shafii, M. B ; Nobakhti, M. H ; Sharif University of Technology
    Hindawi Publishing Corporation  2015
    Abstract
    The effect of a magnetic field on the fully developed forced convection of Fe3O4 flow inside a copper tube is experimentally and numerically investigated. The flow is assumed to be under uniform heat flux. This study aims to examine the effects of the nanoparticle volume fraction, as well as alternating magnetic field strength and frequency, on the convective heat transfer for different Reynolds numbers. To ensure accuracy, the numerical results are validated by empirical results with similar geometry and boundary conditions. A satisfying agreement was achieved. The results show that the heat transfer increases with increase in alternating magnetic field frequency but... 

    Synthesis of TiO2 nano powder by the sol-gel method and its use as a photocatalyst

    , Article Journal of the Iranian Chemical Society ; Volume 7, Issue SUPPL. 1 , 2010 , Pages S154-S160 ; 1735207X (ISSN) Karami, A ; Sharif University of Technology
    2010
    Abstract
    In this work the titanium dioxide powder was prepared by the optimized and simple Sol-Gel method and then characterized. The gelling pH was set to values of 3 (TiO2-A), 7 (TiO2-N) and 9 (TiO2-B) to observe the effect on the properties of the material. In these three cases nanoparticulated materials were obtained with particle sizes between 10nm and 20nm. The larger surface areas were obtained at pH 3, which is several times larger than the others. Furthermore, with the gelling condition pH 3, it was possible to synthesize pure anatase phase titania. Some preliminary results on the test of the photocatalytic activity of the synthesized materials in the reduction of nitric oxide are presented.... 

    Selective aqueous oxidation of alcohols catalyzed by copper (II) phthalocyanine nanoparticles

    , Article Comptes Rendus Chimie ; Volume 19, Issue 3 , 2016 , Pages 313-318 ; 16310748 (ISSN) Kheirjou, S ; Kheirjou, R ; Rezayan, A. H ; Shakourian Fard, M ; Mahmoudi Hashemi, M ; Sharif University of Technology
    Elsevier Masson SAS 
    Abstract
    A new catalyst based on metallophthalocyanine nanoparticles has been synthesized and characterized by scanning electron microscopy (SEM). The aqueous oxidation of alcohols to the corresponding carbonyl compounds (aldehydes and ketones) has been studied using tetra-n-butyl-ammonium-peroxo-monosulfate (n-Bu4NHSO5) as an oxidant and a catalytic system consisting of copper (II) phthalocyanine nanoparticles in water. The highly selective oxidation gave excellent yields of related aldehydes or ketones without remarkable over-oxidation of the carboxylic acids. Organic co-solvents, surfactants, and co-catalysts were not used in this catalytic strategy. This strategy was green and time effective. The... 

    Nanoparticle-based optical sensor arrays

    , Article Nanoscale ; v. 9 , 2017 , pages 16546 – 16563 ; 2040-3364 Hormozi-Nezhad, M. R ; Bigdeli, Arafeh ; Ghasemi, Forough ; Golmohammadi, Hamed ; Abbasi-Moayed, Samira ; Farahmand Nejad, M. Amin ; Fahimi-Kashani, Nafiseh ; Jafarinejad, Somayeh ; Shahrajabian, Maryam ; Sharif University of Technology
    Royal Society of Chemistry  2017
    Abstract
    As in many other methods that have integrated nanoparticles (NPs), the chemical nose/tongue strategy has also progressed greatly since the entrance of NPs into this field. The fascinating tunable physicochemical properties of NPs have made them powerful candidates for array-based sensing platforms and have enabled the development of real-time, sensitive and portable systems that are able to target complex mixtures of analytes. In particular, the unique optical properties of NPs have a key role in providing promising array-based sensing approaches. This review will describe the main aspects and processes of most common NP-based optical sensor arrays. The fundamental steps in the design of a... 

    Biocompatibility and hyperthermia efficiency of sonochemically synthesized magnetic nanoparticles

    , Article SPIN ; Volume 9, Issue 2 , 2019 ; 20103247 (ISSN) Talebi, M ; Malaie Balasi, Z ; Ahadian, M. M ; Hatamie, S ; Shahsavari Alavijeh, M. H ; Ghafuri, H ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2019
    Abstract
    Hereby, a sonochemical method for synthesis of pure magnetic Fe3O4Onanoparticles (Fe3O4-NPs) in large scale is being introduced. Synthesis proceeds via simple approach, at room temperature, under sonication, using cheap reagents, green antioxidant-reductant reagent and without using inert gas purge as protective atmosphere condition. During this procedure, hydrogen gas releases continuously as valuable byproduct at the anaerobic step of reaction. Characterizations' results indicate that the final product is pure spherical Fe3O4-NPs, with narrow size distribution and about less than 32nm in mean diameter while more than 99% of particles size were less than 40nm. According to Vibrational...