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    Direct electron transfer of myoglobin on CdO nanoparticles modified glassy carbon electrode

    , Article International Journal of Electrochemical Science ; Volume 8, Issue 5 , 2013 , Pages 7345-7356 ; 14523981 (ISSN) Mohammadi, N ; kakavandi, Y. G ; Movassagh, A. A ; Nasereslami, S ; Mohseni, G ; Hajiosseinlo, A ; Sofimaryo, L ; Soleimani, R ; Akbari-dastjerdi, H ; Negahdary, M ; Sharif University of Technology
    In this study, direct electron transfer of myoglobin (Mb) on cadmium oxide (CdO) nanoparticles modified glassy carbon electrode (GCE) was investigated. Prepared CdO nanoparticles were studied by X-Ray diffraction (XRD) and UV-visible absorption methods. All electrochemical studies were performed by cyclic voltammetry (CV) and a potentiostat device. The cyclic voltammogram of Mb/ CdO Nps/ GCE showed a couple of stable redox and oxidative peaks at -470 and -370 mV at scan rate of 50 mVs-1, respectively. The formal potential (Eo) of myoglobin was calculated as -(420 ± 3) mV. Direct electrode transfer led to design a biosensor for determination of hydrogen peroxide (H2O2). The sensor sensitivity... 

    Natural gas sweetening using ionic liquids, experiment and modeling

    , Article CHISA 2012 - 20th International Congress of Chemical and Process Engineering and PRES 2012 - 15th Conference PRES, 25 August 2012 through 29 August 2012 ; August , 2012 Safavi, M ; Ghotbi, C ; Jalili, A. H ; Taghikhani, V ; Sharif University of Technology
    A discussion covers the general descriptions and basic properties of ionic liquids (IL); main application areas, e.g., solvent replacement, purification of gases, homogenous and heterogeneous catalysis, biological reactions media, and removal of metal ions; and results of the research and works relating to gas solubility measurement and thermodynamic modeling of gas solubility with focus on acid gas solubility in IL. This is an abstract of a paper presented at the CHISA 2012 - 20th International Congress of Chemical and Process Engineering and PRES 2012 - 15th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction (Prague, Czech Republic... 

    Preparation and characterization of Co-Mo catalyst supported on CNT coated cordierite monoliths utilized for naphta HDS process

    , Article Procedia Engineering ; Volume 42 , 2012 , Pages 1484-1492 ; 18777058 (ISSN) Soghrati, E ; Kazemeini, M ; Rashidi, A. M ; Jafari Jozani, Kh ; Sharif University of Technology
    In the present study, an acid treatment of the cordierite monolith followed by coating of the CNT onto it by means of catalytic chemical-vapor deposition (CCVD) of methane over CoMo catalyst was performed. The resulting material utilized as the supports for the HDS catalyst onto which was deposited Co and Mo species. The as-prepared samples were characterized by the BET, XRD, FESEM and ICP-MS techniques. BET experiments showed that a significant increase in specific surface area and pore volume was observed, and a suitable pore size distribution was obtained after acid pretreatment. The FESEM images of CNT coated monolith showed that CNTs were distributed uniformly on the surface of monolith... 

    An overview of tight-binding method for two-dimensional carbon structures

    , Article Graphene: Properties, Synthesis and Applications ; 2012 , Pages 1-36 ; 9781614709497 (ISBN) Gharekhanlou, B ; Khorasani, S ; Sharif University of Technology
    Since the advent of graphene, the two-dimension allotrope of carbon, there has been a growing interest in calculation of quantum mechanical properties of this crystal and its derivatives. To this end, the tight-binding model has been in frequent use for a relatively long period of time. This review, presents an in-depth survey on this method as possible to graphene and two of the most important related structures, graphene anti-dot lattice, and graphane. The two latter derivatives of graphene are semiconducting, while graphane is semimetallic. We present band structure and quantum mechanical orbital calculations and justify the results with the density function theory  

    Electrochemical oxidation mechanisms of the antioxidants daidzein and 7-Hydroxy-4-chromone

    , Article Electroanalysis ; Volume 24, Issue 3 , 2012 , Pages 618-626 ; 10400397 (ISSN) Fernandes, I. P. G ; Oliveira, S. C. B ; Ghalkhani, M ; Shahrokhian, S ; Oliveira Brett, A. M ; Sharif University of Technology
    The electrochemical behavior of antioxidants daidzein (DZ) and 7-hydroxy-4-chromone (7-OH-4-CHM) was investigated. The oxidation of DZ is irreversible, pH-dependent, and occurs in two steps, the first of 4′-OH on the B-ring and the second on the 7-OH on the A-ring. The oxidation of 7-OH-4-CHM occurs on the 7-OH on the A-ring, is irreversible, pH-dependent and proceeds in a single step. The DZ diffusion coefficient was calculated in pH7.0 phosphate buffer to be D DZ=8.1×10 -5cm 2s -1. The detection limits of DZ and 7-OH-4-CHM was calculated as LOD DZ=0.08μM and LOD 7-OH-4-CHM=0.13μM  

    The relation between ink agglomerate size and pore size distribution of the cathode catalyst layer of PEM fuel cells and the effect of carbon corrosion on CCL structure

    , Article AIChE Annual Meeting, Conference Proceedings, 13 March 2011 through 17 March 2011, Chicago, IL ; 2011 ; 9780816910670 (ISBN) Baghalha, M ; Eikerling, M ; Sharif University of Technology
    Carbon corrosion is a major degradation mechanism in cathode catalyst layers (CCL) of polymer electrolyte membrane (PEM) fuel cells. Carbon corrosion (coupled with ionomer dissolution/degradation) induces severe changes in the CCL structure. In the present study, the inter-relation between the particle size of a packed sphere medium and the pore size distribution (PSD) is established. This relation is then used to predict the agglomerate size of the mix of Pt/C and ionomer in the catalyst ink, using experimentally measured PSD of the CCL. During cell degradation, the size of these agglomerates decreases; since, carbon corrosion causes carbon particles to decrease in size. Furthermore, as... 

    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... 

    Formation of carbon nanotubes in iron-catalyzed liquid arcing method: Effect of iron-ion charge in the aqueous medium

    , Article International Journal of Modern Physics B ; Volume 25, Issue 32 , 2011 , Pages 4411-4417 ; 02179792 (ISSN) Shervin, Sh ; Gheytani, S ; Simchi, A ; Sharif University of Technology
    Carbon nanotubes (CNTs) were synthesized via arc discharge in aqueous solutions containing ferrous and ferric irons to reveal the effect of iron-charge mole ratio, R = [Fe 2+]/[Fe 3+], on the purity of CNTs and the process yield. Raman spectroscopy and transmission electron microscopy were used to analyze the cathodic deposits. It is shown that the nucleation of multi-walled CNTs is catalyzed by ferric irons while their growth is affected by ferrous ions. Well-graphitized CNTs with a high-yield are obtained at R = 1 and total iron concentration of 0.05 M. The effect of iron charge is described based on the two-stage formation mechanism  

    Correlation of specific ampere draw with rock brittleness indexes in rock sawing process

    , Article Archives of Mining Sciences ; Volume 56, Issue 4 , 2011 , Pages 777-788 ; 08607001 (ISSN) Mikaeil, R ; Ozcelik, Y ; Ataei, M ; Yousefi, R ; Sharif University of Technology
    The aim of this study is to investigate the effect of the rock brittleness indexes on the specific ampere draw of the circular diamond saws. In this study, twelve rock types belonging to granite and carbonate rock were cut with two different types of circular diamond saws on a fully instrumented laboratory-sawing rig at different feed rate and depths of cut. Rock samples were collected from factories from Iran for laboratory tests and uniaxial compressive strength and tensile strength were determined. The brittleness of B 1 (the ratio of compressive strength to tensile strength), B 2 (the ratio of compressive strength minus tensile strength to compressive strength plus tensile strength), and... 

    Sensitive electrochemical sensor for determination of methyldopa based on polypyrrole/carbon nanoparticle composite thin film made by in situ electropolymerization

    , Article Electroanalysis ; Volume 23, Issue 9 , 2011 , Pages 2248-2254 ; 10400397 (ISSN) Shahrokhian, S ; Saberi, R. S ; Kamalzadeh, Z ; Sharif University of Technology
    A composite surface coating is prepared by electropolymerization of a mixture of pyrrole and carbon nanoparticles onto a glassy carbon electrode (GCE). The microscopic structure and morphology of the composite film is characterized by scanning electron microscopy. The modified electrode offers a considerable improvement in voltammetric sensitivity toward methyldopa (m-dopa), compared to the bare and polypyrrole-coated GCEs. A significantly enhanced anodic peak current together with a remarkable increase in sharpness of the cyclic voltammetric (CV) signals are observed for the detection of m-dopa. The effect of experimental parameters, such as scan rate and pH, are investigated by monitoring... 

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

    , Article Journal of Industrial and Engineering Chemistry ; Volume 28 , August , 2015 , Pages 202-210 ; 1226086X (ISSN) Tourani, S ; Khorasheh, F ; Rashidi, A. M ; Safekordi, A. A ; Sharif University of Technology
    Korean Society of Industrial Engineering Chemistry  2015
    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.%... 

    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
    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... 

    Electrochemical determination of piroxicam on the surface of pyrolytic graphite electrode modified with a film of carbon nanoparticle-chitosan

    , Article Microchimica Acta ; Volume 170, Issue 1 , August , 2010 , Pages 141-146 ; 00263672 (ISSN) Shahrokhian, S ; Jokar, E ; Ghalkhani, M ; Sharif University of Technology
    The electrochemical behavior of the anti-inflammatory drug piroxicam is studied at the surface of a plain pyrolytic graphite electrode modified with chitosan-doped carbon nanoparticles. An electroactive surface was produced by drop-casting a suspension of the modifier and characterized by atomic force microscopy. A remarkable enhancement is found in studies on the cyclic voltammetric response towards piroxicam. This is described on the basis of the thin-layer mass transport regimes within the porous films, which leads to a considerable increase in the active surface area of the electrode. The electrode shows a linear response to piroxicam in the range of 0.05-50 μM, with a detection limit of... 

    Voltammetric determination of dopamine at the surface of TiO2 nanoparticles modified carbon paste electrode

    , Article International Journal of Electrochemical Science ; Volume 5, Issue 1 , 2010 , Pages 147-157 ; 14523981 (ISSN) Mazloum-Ardakani, M ; Rajabi, H ; Beitollahi, H ; Mirjalili, B.B.F ; Akbari, A ; Taghavinia, N ; Sharif University of Technology
    In the present paper, the use of a novel carbon paste electrode modified by N,N'(2,3-dihydroxybenzylidene)-1,4-phenylenediamine (DHBPD) and TiO2 nanoparticles prepared by a simple and rapid method for the determination of dopamine (DA) was described. In the first part of the work, cyclic voltammetry was used to investigate the redox properties of this modified electrode at various solution pH values and at various scan rates. A linear segment was found with slope value of about 48 mV/pH in the pH range 2.0 -12.0. The apparent charge transfer rate constant (ks) and transfer coefficient (α) for electron transfer between DHBPD and TiO2 nanoparticles-carbon paste electrode were calculated. In... 

    Determination of ascorbic acid in the presence of uric acid and folic acid by a nanostructured electrochemical sensor based on a TiO2 nanoparticle carbon paste electrode

    , Article Analytical Letters ; Volume 43, Issue 16 , 2010 , Pages 2618-2630 ; 00032719 (ISSN) Mazloum Ardakani, M ; Talebi, A ; Beitollahi, H ; Naeimi, H ; Taghavinia, N ; Sharif University of Technology
    A carbon paste electrode (CPE), modified with novel hydroquinone/TiO2 nanoparticles, was designed and used for simultaneous determination of ascorbic acid (AA), uric acid (UA) and folic acid (FA). The magnitude of the peak current for modified TiO2-nanoparticle CPE (MTNCPE) increased sharply in the presence of ascorbic acid and was proportional to its concentration. A dynamic range of 1.0-1400.0 μM, with the detection limit of 6.4x10-7M for AA, was obtained using the DPV technique (pH=7.0). The prepared electrode was successfully applied for the determination of AA, UA, and FA in real samples  

    Effect of carbon nanotube geometries on mechanical properties of nanocomposite via nanoscale representative volume element

    , Article Journal of Solid Mechanics ; Volume 8, Issue 3 , 2016 , Pages 568-577 ; 20083505 (ISSN) Moghaddam, F ; Ghavanloo, E ; Fazelzadeh, S. A ; Sharif University of Technology
    Islamic Azad University  2016
    Predicting the effective elastic properties of carbon nanotube-reinforced nanocomposites is of great interest to many structural designers and engineers for improving material and configuration design in recent years. In this paper, a finite element model of a CNT composite has been developed using the Representative volume element (RVE) to evaluate the effective material properties of nanocomposites. Based on this model, the effects of geometrical characteristics such as the aspect ratio, orientation and volume fraction of the CNTs in conjunction with the interphase behavior on the mechanical properties of the nanocomposites are elucidated and the elastic properties of a complex polymeric... 

    Low-temperature gas-solid carbonation of magnesia and magnesium hydroxide promoted by non-immersive contact with water

    , Article RSC Advances ; Volume 6, Issue 92 , 2016 , Pages 89655-89664 ; 20462069 (ISSN) Highfield, J ; Chen, J ; Haghighatlari, M ; Åbacka, J ; Zevenhoven, R ; Sharif University of Technology
    Royal Society of Chemistry  2016
    From gas-solid carbonation studies and product characterization by XRD, carbon elemental analysis, and TG-FTIR profiling of evolved CO2, the presence of water vapour at high relative humidity (>25% RH) was shown to cause a drastic acceleration in the rate of CO2 absorption into MgO and Mg(OH)2 producing magnesite and hydrocarbonated precursors. From thermogravimetric experiments in the vicinity of the dew point, carbonation was shown to proceeded in steps triggered by spontaneous condensation (and re-evaporation) of water. Almost complete conversion to magnesite (MgCO3) and/or hydromagnesite [HM = 4MgCO3·Mg(OH)2·4H2O] was observed in a few hours under rather mild conditions of pressure (PCO2... 

    Biomimetic sensor for dobutamine employing Nano- TiO2/Nafion/carbon nanoparticles modified electrode

    , Article Electroanalysis ; Volume 28, Issue 5 , 2016 , Pages 970-978 ; 10400397 (ISSN) Shahrokhian, S ; Ghalkhani, M ; Kohansal, R ; Mohammadi, R ; Sharif University of Technology
    Wiley-VCH Verlag  2016
    A novel voltammetric biosensor based on nano-TiO2/nafion/carbon nanoparticles modified glassy carbon electrode (TiO2/N/CNP/GCE) was developed for the determination of dobutamine (DBA). Characterization of the surface morphology and property of TiO2/N/CNP layer was carried out by the scanning electron microscopy and atomic force microscopy. The electrochemical performance of the modified electrode was investigated by means of the cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy techniques. Effective experimental variables, such as the scan rate, pH of the supporting electrolyte, drop size of the casted modifier suspension and accumulation... 

    Composites of carbon nanotubes with the blend of poly(vinylidene fluoride)/poly(vinyl acetate)

    , Article Polymer (Korea) ; Volume 40, Issue 2 , 2016 , Pages 232-237 ; 0379153X (ISSN) Davand, R ; Frounchi, M ; Sharif University of Technology
    Polymer Society of Korea  2016
    Poly(vinylidene fluoride)/poly(vinyl acetate)/carbon nanotubes, PVDF/PVAc/CNT, composite films were prepared at various compositions via a solution casting method. The amorphous PVAc formed a miscible blend with PVDF and drastically improved dispersion of CNT in PVDF/CNT composites. Combination of ductile PVAc and rigid CNT had favorable effects on mechanical properties of PVDF. The elongation of PVDF increased from 8% to 300% with addition of 40 wt% PVAc and 0.5 wt% CNT and the modulus at 1.5 wt% CNT was almost 2.3 fold of that of the neat PVDF while retaining high ductility and tensile strength. XRD and FTIR results showed that CNT favored formation of β-crys-talline phase in PVDF. Also... 

    Physicomechanical properties of spark plasma sintered carbon nanotube-reinforced metal matrix nanocomposites

    , Article Progress in Materials Science ; Volume 90 , 2017 , Pages 276-324 ; 00796425 (ISSN) Azarniya, A ; Azarniya, A ; Sovizi, S ; Madaah Hosseini, H. R ; Varol, T ; Kawasaki, A ; Ramakrishna, S ; Sharif University of Technology
    The technological and industrial needs for development of fully dense nanocomposites have led to significant advances in spark plasma sintering (SPS) technique and its enhanced forms. This technique has opened up a new prospect over carbon nanotube (CNT)-metal matrix nanocomposites (MMNCs) with superior physical or mechanical characteristics. To date, a large number of authentic papers have been published over this ongoing field, but have not been comprehensively reviewed. The pertinent research works cover some significant aspects of CNT-MMNCs requiring a concise review on (i) the potential phase transformations of pure CNTs and microstructure evolution; (ii) the novel approaches for...