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    Application of glassy carbon electrode modified with a bilayer of multiwalled carbon nanotube and polypyrrole doped with Nitrazine Yellow for voltammetric determination of naltrexone

    , Article Electroanalysis ; Volume 23, Issue 12 , NOV , 2011 , Pages 2925-2934 ; 10400397 (ISSN) Shahrokhian, S ; Kamalzadeh, Z ; Saberi, R. S ; Sharif University of Technology
    A new sensitive electrochemical sensor was fabricated based on a layer by layer process. In this process the glassy carbon electrode (GCE) is first coated by a thin film of multiwalled carbon nanotubes (MWCNTs). In the next step, the electropolymerization of pyrrole in the presence of Nitrazine Yellow (NY) as a dopant anion is performed on the surface of the MWCNTs precoated electrode. The electrochemical response characteristics of the modified electrode toward naltrexone (NTX) were studied by means of linear sweep voltammetry (LSV). A remarkable increase (~19 times) was observed in the anodic peak current of NTX on the surface of the modified electrode relative to the bare GCE. The effects... 

    Gold electrode modified with self-assembled monolayer of cysteamine-functionalized mwcnt and its application in simultaneous determination of dopamine and uric acid

    , Article Electroanalysis ; Volume 24, Issue 2 , February , 2012 , Pages 425-432 ; 10400397 (ISSN) Shahrokhian, S ; Mahdavi Shakib, A ; Ghalkhani, M ; Saberi, R. S ; Sharif University of Technology
    The voltammetric behavior of dopamine (DA) and uric acid (UA) on a gold electrode modified with self-assembled monolayer (SAM) of cysteamine (CA) conjugated with functionalized multiwalled carbon nanotubes (MWCNTs) was investigated. The film modifier of functionalized SAM was characterized by means of scanning electron microscopy (SEM) and also, electrochemical impedance spectroscopy (EIS) using para-hydroquinone (PHQ) as a redox probe. For the binary mixture of DA and UA, the voltammetric signals of these two compounds can be well separated from each other, allowing simultaneous determination of DA and UA. The effect of various experimental parameters on the voltammetric responses of DA and... 

    Investigating the rheological properties of nanofluids of water/hybrid nanostructure of spherical silica/MWCNT

    , Article Thermochimica Acta ; Volume 578 , 20 February , 2014 , Pages 53-58 ; ISSN: 00406031 Baghbanzadeh, M ; Rashidi, A ; Soleimanisalim, A. H ; Rashtchian, D ; Sharif University of Technology
    Regarding the importance of rheological properties of water based drilling fluids, the effects of silica nanospheres, multiwall carbon nanotubes (MWCNTs) and two types of their hybrid, i.e. H1 (80 wt.% silica nanosphere/20 wt.% MWCNT) and H2 (50 wt.% silica nanosphere/50 wt.% MWCNT) on the viscosity and density of distilled water were investigated. According to the results, viscosity and density of the nanofluids increased with the concentration, while they were reduced by increasing the temperature. At high concentrations, the least increase in the viscosity of distilled water by adding the nanomaterials is related to H2 (8.2% increase at 1.0 wt.%). Likewise, the optimum operating... 

    Anomaly in current distribution of multiwall carbon nanotube bundles at high frequencies

    , Article 14th IEEE International Conference on Nanotechnology, IEEE-NANO 2014 ; 2014 , pp. 702-705 ; ISBN: 9781479956227 Farahani, E. K ; Sarvari, R ; Sharif University of Technology
    In this paper, for the first time, current distribution inside multiwall carbon nanotube (MWCNT) bundles is studied in the high frequency range in which resistance becomes saturated. It is shown that current distribution of MWCNT bundles in this range is not strictly decreasing vs. distance from surface as in Cu wires  

    Application of thionine-nafion supported on multi-walled carbon nanotube for preparation of a modified electrode in simultaneous voltammetric detection of dopamine and ascorbic acid

    , Article Electrochimica Acta ; Volume 52, Issue 22 , 2007 , Pages 6310-6317 ; 00134686 (ISSN) Shahrokhian, S ; Zare Mehrjardi, H. R ; Sharif University of Technology
    A modified carbon-paste electrode (CPE) is prepared by incorporating thionine-nafion supported on multi-walled carbon nanotube (MWCNT). The electrochemical behavior of dopamine (DA) and ascorbic acid (AA) on the surface of the modified electrode is investigated by cyclic voltammetry (CV). The results show that thionine effectively immobilized in the matrix of the paste by using an appropriate mixture of nafion/MWCNT under the ultrasonic condition. On the other hand, presence of nafion enhances the stability of the thionine supported by MWCNT in the composite electrode and improves the reproducibility of the surface of the modified electrode under renewing process by polishing. The results of... 

    Stability analysis in multiwall carbon nanotube bundle interconnects

    , Article Microelectronics Reliability ; Volume 52, Issue 12 , 2012 , Pages 3026-3034 ; 00262714 (ISSN) Haji Nasiri, S ; Faez, R ; Moravvej Farshi, M. K ; Sharif University of Technology
    Based on the transmission line model (TLM), we present an exact and general transfer function formula, useful for both single multiwall carbon nanotube (MWCNT) and MWCNT bundle interconnects. Using the standard parameters for 22-nm technology node we perform the Nyquist stability analysis, to investigate the dependence of the degree of relative stability for both single and bundle interconnects on the number of walls in each MWCNT its geometry and also on the bundle geometry. The numerical results, for 1- to 30-μm long interconnects composed of 3- to 7-wall-CNTs, show that by increasing the length or the outer shell diameter, both single and bundle interconnects become more stable. On the... 

    Carbon paste electrode incorporating multi-walled carbon nanotube/cobalt salophen for sensitive voltammetric determination of tryptophan

    , Article Sensors and Actuators, B: Chemical ; Volume 123, Issue 2 , 2007 , Pages 942-949 ; 09254005 (ISSN) Shahrokhian, S ; Fotouhi, L ; Sharif University of Technology
    A modified carbon paste electrode is prepared by incorporating multi-walled carbon nanotube (MWCNT) and cobalt salophen (CoSal). A mixture of fine graphite powder with 10 wt% of MWCNT is applied for the preparation of carbon paste (by dispersing in Nujol) and finally modified with CoSal. The electrocatalytic oxidation of tryptophan (Trp) is investigated on the surface of the MWCNT/CoSal-modified electrode using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Using the modified electrode, the kinetics of the electro-oxidation of Trp is considerably enhanced, by lowering the anodic overpotential through a catalytic fashion. The mechanism of electrochemical behavior of Trp at... 

    Investigation of mechanical properties, antibacterial features, and water vapor permeability of polyvinyl alcohol thin films reinforced by glutaraldehyde and multiwalled carbon nanotube

    , Article Polymer Composites ; Vol. 35,Issue. 9 , 2014 , pp. 1736-1743 ; ISSN: 1548-0569 Mohammad Mahdi Dadfar, S ; Kavoosi, G ; Mohammad Ali Dadfar, S ; Sharif University of Technology
    Polyvinyl alcohol (PVA) thin films were reinforced by glutaraldehyde and multiwalled carbon nanotubes (MWCNTs) and then mechanical, water solubility, water swelling, water uptake, water vapor permeability, and antibacterial properties of the films were examined. Cross-linking by glutaraldehyde or incorporation of MWCNT caused a significant increase in tensile strength, decrease in elongation at break, and increase in Young's modulus of the PVA films, while MWCNTs were more effective rather than that of glutaraldehyde. Cross-linking by glutaraldehyde or incorporation of MWCNT caused a significant decrease in water solubility, water swelling and water uptake, with a similar manner.... 

    Synthesis and electrochemical characterization of sol-gel-derived RuO 2/carbon nanotube composites

    , Article Journal of Solid State Electrochemistry ; Vol. 18, Issue 4 , April , 2014 , pp. 993-1003 ; Online ISSN: 1433-0768 Kahram, M ; Asnavandi, M ; Dolati, A ; Sharif University of Technology
    Ruthenium oxide was coated on multiwalled carbon nanotubes (MWCNTs) to obtain nanocomposite electrode which has a good response to the pH. To synthesize this electrode, gold and cobalt were coated on a stainless steel 304 substrates, respectively, and then, vertically aligned carbon nanotubes were grown on the prepared substrates by chemical vapor deposition. Gold reduced activity of the stainless steel, while cobalt served as a catalyst for growth of the carbon nanotube. Ruthenium oxide was then coated on MWCNTs via sol-gel method. At last, different techniques were used to characterize the properties of synthesized electrode including scanning electron microscopy (SEM), transmission... 

    Fabrication of an electrochemical sensor based on the electrodeposition of Pt nanoparticles on multiwalled carbon nanotubes film for voltammetric determination of ceftriaxone in the presence of lidocaine, assisted by factorial-based response-surface methodology

    , Article Journal of Solid State Electrochemistry ; Vol. 18, issue. 1 , 2014 , p. 77-88 Shahrokhian, S ; Hosseini-Nassab, N ; Kamalzadeh, Z ; Sharif University of Technology
    A glassy carbon electrode (GCE) is modified with platinum nanoparticle (PtNPs) decorated multiwalled carbon nanotube (MWCNT). The modified electrode is applied for the determination of ceftriaxone (CFX) in the presence of lidocaine. Different methods were used to characterize the surface morphology of the modified electrode. The electrochemical behavior of CFX was investigated at GCE, MWCNT/GCE and PtNPs/MWCNT/GCE. A factorial-based response-surface methodology was used to find out the optimum conditions with minimum number of experiments. Under the optimized conditions, oxidation peak currents increased linearly with CFX concentration in the range of 0.01-10.00 μM with a detection limit of... 

    Improvement in oil absorbency by using modified carbon nanotubes in preparation of oil sorbents

    , Article Advances in Polymer Technology ; Volume 32, Issue 1 , 2013 ; 07306679 (ISSN) Pourjavadi, A ; Doulabi, M ; Sharif University of Technology
    This article reports the first oil-absorbent cross-linked copolymer consisting of modified multiwalled carbon nanotube (MWCNT) and showing high oil absorbency. Also, to investigate and evaluate the effective parameters on oil absorbency, cross-linked dodecyl methacrylate (DDMA)-diphenylacrylamide (DPAA) and DDMA-butyl acrylate (BA) copolymers were synthesized. DDMA was copolymerized with different mol% of DPAA or BA and cross-linked using azobisisobutyronitrile as the initiator and various weight percentages of 1,4-butandiol dimethacrylate, methylene bisacrylamide, or vinyl group-modified MWCNT cross-linkers. The effects of monomer feed composition, cross-linker concentration, and the... 

    Synthesis of spherical silica/multiwall carbon nanotubes hybrid nanostructures and investigation of thermal conductivity of related nanofluids

    , Article Thermochimica Acta ; Volume 549 , 2012 , Pages 87-94 ; 00406031 (ISSN) Baghbanzadeh, M ; Rashidi, A ; Rashtchian, D ; Lotfi, R ; Amrollahi, A ; Sharif University of Technology
    In this study, a hybrid of silica nanosphere/multiwall carbon nanotube (MWCNT) has been synthesized by wet chemical method at room temperature. The effect of MWCNTs, silica nanospheres and hybrid nanostructures (80% silica nanosphere/20% MWCNT and 50% silica nanosphere/50% MWCNT) on the thermal conductivity of distilled water has been investigated. SDBS was used as the dispersant to stabilize nanomaterials in the aqueous suspension and its concentration was 1.5 times of the concentration of nanomaterials. As results show, by increasing the concentration of nanomaterials, effective thermal conductivity of nanofluids increased. The most and the least enhancement in the effective thermal... 

    Fabrication of gas ionization sensor using carbon nanotube arrays grown on porous silicon substrate

    , Article Sensors and Actuators, A: Physical ; Volume 162, Issue 1 , 2010 , Pages 24-28 ; 09244247 (ISSN) Nikfarjam, A ; Iraji Zad, A ; Razi, F ; Mortazavi, S. Z ; Sharif University of Technology
    We fabricated gas sensors based on field ionization from multiwalled carbon nanotube (MWCNT) arrays grown on porous silicon templates. MWCNTs were grown through thermal chemical vapor deposition. We measured breakdown voltages, discharge and pre-discharge currents of the device for various gases in different concentrations. Our gas ionization sensors (GIS) presented good sensitivity, selectivity and short response time. The GISs based on porous substrates showed higher discharge current and good mechanical stability in comparison to those which were fabricated on polished silicon substrates. Additionally, we applied a high electric field to align CNTs. This increased the pre-breakdown... 

    A continuum constitutive model for mechanical behavior of 5052 resin epoxy containing various percentages of MWCNTs

    , Article Journal of Composite Materials ; Volume 51, Issue 17 , 2017 , Pages 2423-2434 ; 00219983 (ISSN) Hosseini Kordkheili, S. A ; Toozandehjani, H ; Ashouri Choshali, H ; Boroumand Azad, S ; Sharif University of Technology
    SAGE Publications Ltd  2017
    In this article, a continuum-based constitutive model is developed to predict the mechanical behavior of 5052 resin epoxy reinforced by multiwalled carbon nanotubes (MWCNTs) based on experimentally generated data. For this purpose, MWCNTs/epoxy specimens with various percentages of functionalized and nonfunctionalized MWCNTs are prepared. The SEM graphs indicate that functionalization leads to a better bound between epoxy and MWCNTs and a higher level of dispersion. The specimens are then tested under standard ASTM D638-02 a procedure and their true plastic stress–strain curves are extracted. Investigations on experimentally generated data reveal that a wt% dependent equation which is... 

    Effect of long-chain ionic liquids on the capacitive performance of carbon nanotube-sulfonated polyaniline hydrogels for energy storage applications

    , Article Journal of Physical Chemistry C ; Volume 124, Issue 18 , 2020 , Pages 9810-9821 Hekmat, F ; Shahrokhian, S ; Mirzaei, Y ; Sharif University of Technology
    American Chemical Society  2020
    Imidazolium-based ionic liquids (ILs) have been perceived as a promising candidate for bridging polyaniline (PANI) on well-dispersed carbon nanotubes (CNTs) via formation of IL-stabilized multiwalled carbon nanotubes (MWCNTs) dispersion in which outer walls of CNTs, as well as benzene rings of the aniline monomer and the growing polymer, have been potently effective in such procurement. The sulfonated water-soluble PANI-[C16C1im]Cl-MWCNT nanocomposites (SPANI-IL-MWCNTs) are directly deposited on a graphite-based current collector using a simple and cost-effective electrophoretic deposition (EPD) method. The SPANI-IL-MWCNT electrodes exhibit remarkable electrochemical performance compared to... 

    Hydro-purification of crude terephthalic acid using palladium catalyst supported on multi-wall carbon nanotubes

    , Article Journal of Industrial and Engineering Chemistry ; 2015 ; ISSN: 1226086X Tourani, S ; Khorasheh, F ; Rashidi, A. M ; Safekordi, A. A ; Sharif University of Technology
    Palladium catalysts supported on functionalized multi-wall carbon nanotubes were synthesized for hydro-purification of crude terephthalic acid containing 2100ppm 4-carboxybenzaldehyde (4-CBA) as impurity. PdCl2 and Pd(OAc)2 were used as precursors. Palladium loadings were 0.05 to 0.6wt.% with catalysts reduced at 200 to 400°C. Catalysts prepared from both precursors with least 0.3wt.% palladium resulted in 99%+ removal of 4-CBA. The most desired selectivity was obtained for the catalyst with PdCl2 as precursor, reduction temperature of 300°C, and palladium loading of 0.3wt.%. This catalyst had slightly better performance than the commercial catalyst (0.5wt.% of palladium on activated carbon)... 

    Multiwalled carbon nanotube-polyelectrolyte gels: Preparation and swelling behavior for organic solvents

    , Article Solid State Ionics ; Vol. 257 , 2014 , pp. 32-37 ; ISSN: 01672738 Pourjavadi, A ; Doulabi, M ; Sharif University of Technology
    In this article, we report the first multiwalled carbon nanotube-polyelectrolyte gel containing vinylimidazolium-typed ionic liquid monomer as an absorbent of less-polar or nonpolar organic solvents. To prepare such MWCNT-polyelectrolyte gel, the modified MWCNTs with polymerizable vinyl groups on their surfaces were prepared and then underwent copolymerizations with dodecyl methacrylate and vinylimidazolium in the presence of AIBN as initiator, yielding a cross-linked polyelectrolyte. In order to estimate the compatibility between the solvents and the polymers, a series of vinylimidazolium-typed ionic liquid monomers ([Cnvim][X]) with different alkyl tail length (C6, C10 and C12) and counter... 

    Modification of well-aligned carbon nanotubes with dihexadecyl hydrogen phosphate: Application to highly sensitive nanomolar detection of simvastatin

    , Article Journal of Applied Electrochemistry ; Volume 44, Issue 2 , February , 2014 , Pages 263-277 ; ISSN: 0021891X Fayazfar, H ; Afshar, A ; Dolati, A ; Ghalkhani, M ; Sharif University of Technology
    The first usage of dihexadecyl hydrogen phosphate (DHP)-modified highly oriented multi-walled carbon nanotube (MWCNTs) forests in a sensor configuration was developed to investigate the electrochemical oxidation and determination of simvastatin (SV) in pharmaceutical dosage forms. Synthesis of well-aligned MWCNTs on a conductive Ta substrate by catalytic vapor deposition technique using a common chemical, ethylenediamine, and without being plasma-aided was reported. The electrochemical behavior and oxidation of SV at the aligned MWCNTs/DHP/Ta electrode were discussed in detail through cyclic voltammetry and differential pulse voltammetry. This modified electrode showed considerably higher... 

    Cytotoxicity of protein corona-graphene oxide nanoribbons on human epithelial cells

    , Article Applied Surface Science ; Volume 320 , 30 November , 2014 , Pages 596-601 ; ISSN: 01694332 Mbeh, D. A ; Akhavan, O ; Javanbakht, T ; Mahmoudi, M ; Yahia, L ; Sharif University of Technology
    Graphene oxide nanoribbons (GONRs) were synthesized using an oxidative unzipping of multi-walled carbon nanotubes. The interactions of the GONRs with various concentrations of fetal bovine serum or human plasma serum indicated that the GONRs were functionalized substantially by the albumin originated from the two different protein sources. Then, concentration-dependent cytotoxicity of the protein-functionalized GONRs on human epithelial cells was studied. Although the GONRs with concentrations ≤50 μg/mL did not exhibit significant cytotoxicity on the cells (with the cell viability >85%), the concentration of 100 μg/mL exhibited significant cytotoxicity including prevention of cell... 

    Compact closed form model for skin and proximity effect in multiwall carbon nanotube bundles as GSI interconnects

    , Article IEEE Transactions on Electron Devices ; Vol. 61, issue. 8 , July , 2014 , p. 2899-2904 Farahani, E. K ; Sarvari, R ; Sharif University of Technology
    Closed form model for skin and proximity effect is necessary for GSI interconnects. In this paper, exact formulation for current distribution inside multiwall carbon nanotube (MWCNT) bundles is derived using multiconductor transmission line model. The current distribution is different from copper wires and it is geometry dependent because of kinetic inductance and quantum capacitance. This current distribution is used to compute and formulate high frequency resistance of MWCNT bundles