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    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... 

    The electrocatalytic examination of cephalosporins at carbon paste electrode modified with CoSalophen

    , Article Talanta ; Volume 71, Issue 4 , 2007 , Pages 1669-1674 ; 00399140 (ISSN) Jamasbi, E. S ; Rouhollahi, A ; Shahrokhian, S ; Haghgoo, S ; Aghajani, S ; Sharif University of Technology
    Elsevier  2007
    The electrocatalytic oxidation of cephalexin and cefazolin has been studied at a carbon paste electrode modified with cobalt salophen (CoSal) by cyclic voltammetry. The selectivity of the carbon paste modified with CoSal in detecting cephalexin and cefazolin was examined. To suggest the electrocatalytic mechanism for electro-oxidation of cefazolin, the electrochemical behavior of ceftriaxone was investigated which has a thiol group out of the beta lactam ring. The electrocatalytic oxidation of these antibiotics is shown to be irreversible at the CoSal modified electrode. Scan rate dependence of cefazolin, which is a sulfur-containing compound, has been examined. The results indicated that... 

    Modification of a glassy carbon electrode with a bilayer of multiwalled carbon nanotube/benzene disulfonate-doped polypyrrole: Application to sensitive voltammetric determination of olanzapine

    , Article RSC Advances ; Vol. 4, Issue. 76 , Aug , 2014 , pp. 40553-40560 ; ISSN: 20462069 Shahrokhian, S ; Azimzadeh, M ; Hosseini, P ; Sharif University of Technology
    A glassy carbon electrode was coated with a thin layer of multi-walled carbon nanotubes and subsequently was electro-polymerized with polypyrrole. The prepared electrode was used for the voltammetric determination of olanzapine (OLZ). The peak current of OLZ increases remarkably on the surface of the modified electrode. This is due to the large increase in the microscopic area of the electrode surface along with the strong adsorption of OLZ on the surface of the electrode. The film modifier was characterized by scanning electron microscopy, atomic force microscopy and cyclic voltammetry techniques. Experimental variables, such as deposited amount of nanotube suspension, pH of the supporting... 

    Effect of the reactance term on the charge/discharge electrical measurements using cylindrical capacitive probes

    , Article Journal of Applied Sciences ; Volume 11, Issue 18 , 2011 , Pages 3293-3300 ; 18125654 (ISSN) Behzadi, G ; Fekri, L ; Golnabi, H ; Sharif University of Technology
    In this study, operation of the contact Cylindrical Capacitive Sensor (CCS) for the reactance capacitance measurement of the water liquids by using the charge/discharge measurement module is investigated. The effect of geometric factor on the capacitance measurement of different liquid samples is also studied. The measured capacitances for the distilled, mineral, tap and salt water samples are reported by using two contact CCSs with the active length of 16 and 74 mm. The measured capacitances by small contact CCS for the saltwater is 1.76 uF and by big contact CCS is 47.8 uF, which shows a big difference for different probes. In another study, the effects of the liquid conductance on the... 

    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
    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... 

    Erratum: Circuit model in design of THZ transparent electrodes based on two-dimensional arrays of metallic square holes (IEEE transactions on terahertz science and technology (2014) 4:3 (383-390))

    , Article IEEE Transactions on Terahertz Science and Technology ; Volume 5, Issue 4 , June , 2015 , Pages 655-656 ; 2156342X (ISSN) Khavasi, A ; Mehrany, K ; Shirmanesh, G. K ; Yarmoghaddam, E ; Sharif University of Technology
    IEEE Microwave Theory and Techniques Society  2015
    A circuit model has been proposed for two-dimensional metallic arrays of metallic square holes located on a homogeneous substrate. Although the proposed circuit model holds true, the surface admittance between the metallic hole array and the cover was erroneously calculated since the presence of the cross-polarization terms had been neglected. Furthermore, there have been mistakes in numerical simulation and in analytical calculations based on the presented formulas. The correct formulation is now given, and erroneous figures are replotted  

    Voltammetric behavior and determination of trace amounts of omeprazole using an edge-plane pyrolytic graphite electrode

    , Article Iranian Journal of Pharmaceutical Research ; Volume 14, Issue 2 , Spring , 2015 , Pages 465-471 ; 17350328 (ISSN) Shahrokhian, S ; Ghalkhani, M ; Bayat, M ; Ghorbani Bidkorbeh, F ; Sharif University of Technology
    Iranian Journal of Pharmaceutical Research  2015
    The voltammetric performance of edge-plane pyrolytic graphite (EPG) electrode via adsorptive stripping voltammetry was investigated for study of the electrochemical behavior of omeprazole (OMZ) in aqueous solution. The results revealed that the oxidation of OMZ is an irreversible pH-dependent process that proceeds with the transfer of one electron and one proton in an adsorption-controlled mechanism. The determination conditions, such as the pH values of the supporting electrolyte, accumulation time and scan rate were optimized. Simplicity, high reproducibility and low detection limit (3 nM) of the electrode response as well as wide linear range (0.01 to 4.0 µM) can be stated as significant... 

    A sensitive voltammetric morphine nanosensor based on BaFe12O19 nanoparticle-modified screen-printed electrodes

    , Article Journal of the Iranian Chemical Society ; Volume 17, Issue 3 , 2020 , Pages 717-724 Bagherinasab, Z ; Beitollahi, H ; Yousefi, M ; Bagherzadeh, M ; Hekmati, M ; Sharif University of Technology
    Springer  2020
    Morphine is a strong opioid used for the treatment of moderate to severe pain. Its use is, however, associated with adverse effects including sedation, nausea, constipation, respiratory depression, and development of tolerance as well as dependence. Thus, in this work electrochemical oxidation of morphine has been done on BaFe12O19 nanoparticles of the modified electrode. BaFe12O19 nanoparticles of the modified graphite screen-printed electrode (GSPE) and the bare GSPE were compared, representing that the modified electrode takes advantages of higher sensitivities and selectivities with lower limit of detection. Differential pulse voltammetric procedure has been used to analyze data. Results... 

    Electrocatalytic oxidation of methane at nickel hydroxide modified nickel electrode in alkaline solution

    , Article Electrochemistry Communications ; Volume 5, Issue 2 , 2003 , Pages 184-188 ; 13882481 (ISSN) Jafarian, M ; Mahjani, M. G ; Heli, H ; Gobal, F ; Heydarpoor, M ; Sharif University of Technology
    Elsevier Inc  2003
    Nickel hydroxide modified nickel electrodes prepared by cycling the potential of a nickel electrode in alkaline solution exhibited electrocatalytic activity for the oxidation of methane in alkaline media. In the presence of methane the oxidation peak current of nickel hydroxide increases while that of the reverse process decreases. This is attributed to the mediation of nickel species, probably β-NiOOH phase, in the process of electrocatalysis. The mechanism of methane oxidation has also been discussed in terms of the formations of intermediates normally encountered in small organics electro-oxidation. It has also been suggested that in the further oxidation of the intermediates, ions in the... 

    Iodide-selective electrode based on copper phthalocyanine

    , Article Electroanalysis ; Volume 14, Issue 23 , 2002 , Pages 1621-1628 ; 10400397 (ISSN) Shahrokhian, S ; Taghani, A ; Moattar, F ; Sharif University of Technology
    Copper phthalocyanine was used as ion carrier for preparing polymeric membrane selective sensor for detection of iodide. The electrode was prepared by incorporating the ionophore into plasticized poly(vinyl chloride) (PVC) membrane, coated on the surface of graphite electrode. This novel electrode shows high selectivity for iodide with respect to many common inorganic and organic anions. The effects of membrane composition, pH and the influence of lipophilic cationic and anionic additives and also nature of plasticizer on the response characteristics of the electrode were investigated. A calibration plot with near-Nernestian slope for iodide was observed over a wide linear range of five... 

    Discharge current development in two-electrode spark gap switches

    , Article IEEE Transactions on Plasma Science ; Volume 30, Issue 1 III , 2002 , Pages 301-309 ; 00933813 (ISSN) Golnabi, H ; Sharif University of Technology
    The present study describes the result of an improved numerical method applied to our two-electrode spark gap discharge. The time evolution of the ionization current is obtained and mechanisms describing ionization growth in discharge are presented. The effect of E/N has been investigated by changing either the applied gap voltage or by varying the nitrogen gas pressure. Some fluctuations in the exponential ionization growth are noticed which are related to the secondary ionization by the cathode photoelectric emission. Simulated snapshots were obtained that clearly show the image of electron avalanches traversing the discharge gap. My results are compared with other computational methods... 

    Signal and noise improvement of travelling wave fet mixers

    , Article 2nd International Conference on Microwave and Millimeter Wave Technology, ICMMT 2000, 14 September 2000 through 16 September 2000 ; 2000 , Pages 76-79 ; 0780357434 (ISBN); 9780780357433 (ISBN) Moradi, G ; Abdipour, A ; Farzaneh, F ; Ghorbani, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2000
    The influence of the loading of the FET electrodes, on signal and noise performances of the device in mixer application is studied. It is shown that exciting the input signal from one end of the gate and extracting the output signal from the opposite ends of the gate can improve the device characteristics, provided that the two remaining ends of the gate and the drain are properly loaded. This structure makes the lines (i.e. the gate and the drain electrodes) to be matched with the loads. Therefore it leads to a travelling wave FET mixer, which is a good candidate for high power mm-wave application. © 2000 IEEE  

    Voltammetric determination of methimazole using a carbon paste electrode modified with a Schiff base complex of cobalt

    , Article Electroanalysis ; Volume 20, Issue 10 , 2008 , Pages 1061-1066 ; 10400397 (ISSN) Shahrokhian, S ; Ghalkhania, M ; Sharif University of Technology
    The electrochemical behavior of methimazole, as an antithyroid agent, is investigated on the surface of a carbon-paste electrode modified with a newly synthesized Schiff base complex of cobalt. The prepared modified electrode showed an efficient catalytic role in the electrochemical oxidation of methimazole, leading to remarkable decrease in oxidation overpotential and enhancement of the kinetics of the electrode reaction. The mechanism of the electrocatalytic process on the surface of the modified electrode is analyzed by obtaining the cyclic voltammograms in various potential sweep rates and pHs of the buffer solutions. The differential pulse voltammetry is applied as a very sensitive... 

    Multi-walled carbon nanotube paste electrode for selective voltammetric detection of isoniazid

    , Article Microchimica Acta ; Volume 157, Issue 3-4 , 2007 , Pages 149-158 ; 00263672 (ISSN) Shahrokhian, S ; Amiri, M ; Sharif University of Technology
    A multi-walled carbon nanotube paste electrode (MWCPE) is prepared as an electrochemical sensor with high sensitivity and selectivity in responding to isoniazid. The electrochemical oxidation of isoniazid is investigated in buffered solution by cyclic and differential pulse voltammetry. The electrode is shown to be very effective for the detection of isoniazid in the presence of other biological reductant compounds. The electrochemical oxidation of cysteine, due to the high overvoltage, is completely stopped at the surface of MWCPE. The electrode exhibits a very good resolution between the voltammetric peak of isoniazid and the peaks of ascorbic acid (AA) and dopamine (DA). A resolution of... 

    Voltammetric studies of propylthiouracil at a carbon-paste electrode modified with cobalt(II)-4-chlorosalophen: Application to voltammetric determination in pharmaceutical and clinical preparations

    , Article Microchimica Acta ; Volume 151, Issue 1-2 , 2005 , Pages 73-79 ; 00263672 (ISSN) Shahrokhian, S ; Jannat Rezvani, M. J ; Sharif University of Technology
    A carbon-paste electrode chemically modified with a Schiff-base complex of cobalt (cobalt(II)-4-chlorosalophen, CoClSal) is utilized to investigate the voltammetric response of propylthiouracil (PTU). The mechanism of electrocatalytic oxidation of the compound is investigated by means of cyclic voltammetric studies applying various pHs to the buffered solutions. The modified electrode exhibits effective catalytic properties that lower the anodic overpotential and enhance the rate of electron transfer for the electrochemical oxidation of PTU. The results of the cyclic voltammetric (CV) and differential pulse voltammetric (DPV) techniques showed that the modified electrode exhibits good... 

    Application of glassy carbon electrode modified with a carbon nanoparticle/melamine thin film for voltammetric determination of raloxifene

    , Article Journal of Electroanalytical Chemistry ; Volume 780 , 2016 , Pages 126-133 ; 15726657 (ISSN) Shahrokhian, S ; Ghalkhani, M ; Balotf, H ; Salimian, R ; Sharif University of Technology
    Elsevier B.V  2016
    As a selective estrogen receptor modulator, raloxifene (RXF) prevent of osteoporosis in postmenopausal women by estrogenic actions on bone and decreases the risk of invasive breast cancer by anti-estrogenic actions on the breast and uterus tissue. However, RXF may increase the risk of blood clots, including deep vein thrombosis and pulmonary embolism. For the first time glassy carbon electrode modified with a thin film of melamine/carbon nanoparticles (CNPs/Mela) was constructed and used for the sensitive voltammetric determination of RXF. In comparison with unmodified electrode, the presence of the CNPs/Mela film resulted in a remarkable increase in the peak currents and sharpness of the... 

    Fabrication of Applied Electrode Materials based on Metal-Organic Frameworks to Design Non-Enzymatic Electrochemical Sensing Platforms for Measuring of Glucose in Physiological Samples

    , M.Sc. Thesis Sharif University of Technology Ezzati, Milad (Author) ; Shahrokhian Dehkordi, Saeed (Supervisor)
    In the first work, the method of direct growth was used to grew MOFs based on cobalt, as electroactive centers, for preparing electrochemical sensors for the determination of glucose. In comparison to most of the electrochemical sensing platforms based on MOFs for determining glucose, which suffer from some disadvantages like time-consuming synthesis procedures and using hazardous organic solvents, the proposed in situ growth method is much faster and no need to toxic organic solvents. Herein, cobalt-based MOFs were grown on the surface of the reduced graphene oxide modified glassy carbon electrode by the direct and rapid conversion of cobalt hydroxide nanosheets intermediates. The... 

    Continuous size-based focusing and bifurcating microparticle streams using a negative dielectrophoretic system

    , Article Microfluidics and Nanofluidics ; Volume 14, Issue 1-2 , 2013 , Pages 265-276 ; 16134982 (ISSN) Hemmatifar, A ; Saidi, M. S ; Sadeghi, A ; Sani, M
    Dielectrophoresis (DEP) is an electrokinetic phenomenon which is used for manipulating micro- and nanoparticles in micron-sized devices with high sensitivity. In recent years, electrode-based DEP by patterning narrow oblique electrodes in microchannels has been used for particle manipulation. In this theoretic study, a microchannel with triangular electrodes is presented and a detailed comparison with oblique electrodes is made. For each shape, the behavior of particles is compared for three different configurations of applied voltages. Electric field, resultant DEP force, and particle trajectories for configurations are computed by means of Rayan native code. The separation efficiency of... 

    Facile synthesis of nanoporous CuS nanospheres for high-performance supercapacitor electrodes

    , Article Journal of Energy Chemistry ; Volume 26, Issue 4 , 2017 , Pages 762-767 ; 20954956 (ISSN) Heydari, H ; Moosavifard, S. E ; Shahraki, M ; Elyasi, S ; Sharif University of Technology
    In recent years, development of high-performance supercapacitor electrode materials has stimulated a great deal of scientific research. The electrochemical performance of a supercapacitor strongly depends on its material structures. Herein, we report a simple strategy for high-performance supercapacitors by building pseudocapacitive CuS nanospheres with nanoporous structures, nanosized walls (<10 nm) and relatively large specific surface area of 65 m2/g. This electrode demonstrates excellent electrochemical performance including a maximum specific capacitance of 814 F/g at 1 A/g, significant rate capability of 42% capacitance retention at an ultrafast rate of 50 A/g, and outstanding... 

    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...