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    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... 

    Simultaneous voltammetric detection of ascorbic acid and uric acid at a carbon-paste modified electrode incorporating thionine-nafion ion-pair as an electron mediator

    , Article Electrochimica Acta ; Volume 51, Issue 13 , 2006 , Pages 2599-2606 ; 00134686 (ISSN) Shahrokhian, S ; Ghalkhani, M ; Sharif University of Technology
    The electrochemical behavior of ascorbic acid (AA) and uric acid (UA) at the surface of a carbon-paste electrode modified with incorporate thionine-nafion ion-paired was thoroughly investigated. The results show the presence of nafion inside the matrix of modified electrode, because of the effective ion-pairing and hydrophobic interactions, significantly enhances the stability of thionine as an electron mediator inside the modified electrode. A high reproducibility in voltammetric response to analyte species results because of this enhancement. The cyclic voltammetric studies using the prepared modified electrode show the best electrocatalytic property for the electro-oxidation of AA and... 

    Investigation on various types of ion-exchange membranes in vanadium redox flow batteries: Experiment and modeling

    , Article Journal of Energy Storage ; Volume 54 , 2022 ; 2352152X (ISSN) Maghsoudy, S ; Rahimi, M ; Molaei Dehkordi, A ; Sharif University of Technology
    Elsevier Ltd  2022
    Choosing the appropriate ion exchange membrane in vanadium redox flow batteries plays an important role in achieving optimal system performance. In this article, the implementation of commercial cation exchange membranes (Nafion 115, Nafion 117, and Nafion 212), anion exchange membranes (FAP 450 and QA-PFE), and the combination of them are investigated. In this regard, the effects of membrane type, thickness, electrical conductivity, and the transfer of vanadium species at different current densities are examined carefully. In addition, the influences of the flow rate and the concentration of electrolytes are investigated using a comprehensive developed model. The model predictions are... 

    Preparation of Proton Exchange Membrane for Microbial Fuel Cell Application

    , M.Sc. Thesis Sharif University of Technology Bazrgar Bajestani, Majid (Author) ; Mousavi, Abbas (Supervisor) ; Mohammad jafar Abdekhodayi (Co-Advisor)
    Synthesis and characterization of Nafion/TiO2 membranes whit different solvent (DMF, DMAc, NMP) for proton exchange membrane fuel cell (PEMFC) were investigated in this study. Nafion/ TiO2 nanocomposite membranes have been prepared by solution casting Method. The structures of membranes were investigated by Scanning Electron Microscopy (SEM). Also water uptake, proton conductivity and ion exchange capacity (IEC) of membranes were measured and compared whit Nafion 112 in microbial fuel cell. The membrane was prepared whit DMF solvent has maximum proton conductivity and best morphology and maximum cell voltage  

    Effect of water-methanol content on the structure of Nafion in the sandwich model and solvent dynamics in nano-channels; A molecular dynamics study

    , Article Molecular Physics ; Volume 109, Issue 5 , Mar , 2011 , Pages 709-724 ; 00268976 (ISSN) Abroshan, H ; Akbarzadeh, H ; Taherkhani, F ; Parsafar, G ; Sharif University of Technology
    Continuing an ongoing study, molecular dynamics (MD) simulations were performed to investigate the effects of methanol concentration on Nafion morphology, such as the size of solvent cluster, solvent location, and polymer structure via the sandwich model. Our survey shows that high methanol concentrations resulted in increment of solvent cluster size in Nafion membrane. The sulfonic acid clusters also befall much in order as subsequent layers of such ionic clusters are formed. The number of neighbouring hydronium ions around a sulfur atom is independent of methanol concentration, but the first shell of hydronium and water around sulfonic acid clusters is broader. Although methanol would... 

    Properties of Nafion Under Uniaxial Loading at Different Temperatures: A Molecular Dynamics Study

    , Article Polymer - Plastics Technology and Engineering ; Volume 54, Issue 8 , 2015 , Pages 806-813 ; 03602559 (ISSN) Ozmaian, M ; Naghdabadi, R ; Sharif University of Technology
    Taylor and Francis Inc  2015
    Nafion membrane encounters many different thermal conditions and mechanical loadings because of its wide range of applications as a proton exchange membrane (PEM). Molecular dynamics simulation of hydrated Nafion at different temperatures is carried out to investigate the alteration of the physical properties of Nafion under uniaxial loading over a wide range of temperatures. According to the simulation results, increase of the temperature reduces the yield stress. The results also show that the polymer chains ordering increases the glass transition temperature and enhances the self-diffusion coefficient of water in hydrated Nafion. Comparisons show that the elastic modulus and viscosity... 

    NAFAS: non-rigid air flow active sensor, a cost-effective, wearable, and ubiquitous respiratory bio-sensor

    , Article IEEE Sensors Journal ; Volume 21, Issue 7 , 2021 , Pages 9530-9537 ; 1530437X (ISSN) Annabestani, M ; Esmaeili Dokht, P ; Khazaee Nejad, S ; Fardmanesh, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    A Non-rigid Air Flow Active Sensor (NAFAS) to detect the respiratory patterns is introduced in this paper. The main part of NAFAS is an ionic electroactive polymer-based ( ${i}$ -EAP) soft sensor. It can accurately detect breathing patterns and has promising features to develop low cost, wearable, and ubiquitous spirometers. Patients with respiratory diseases need to take pulmonary function tests consistently. Hence, it is time-consuming and expensive. To address these problems, NAFAS presents point-of-care testing (POCT) of the respiratory system's function. The proposed ${i}$ -EAP based sensor is a small strip of Ionic Polymer Metal Composite (IPMC) that has been fabricated using a Nafion... 

    Novel high-performance nanocomposite proton exchange membranes based on poly (ether sulfone)

    , Article Renewable Energy ; Volume 35, Issue 1 , 2010 , Pages 226-231 ; 09601481 (ISSN) Hasani-Sadrabadi, M.M ; Dashtimoghadam, E ; Ghaffarian, S.R ; Hasani Sadrabadi, M.H ; Heidari, M ; Moaddel, H ; Sharif University of Technology
    In the present research, proton exchange membranes based on partially sulfonated poly (ether sulfone) (S-PES) with various degrees of sulfonation were synthesized. It was found that the increasing of sulfonation degree up to 40% results in the enhancement of water uptake, ion exchange capacity and proton conductivity properties of the prepared membranes to 28.1%, 1.59 meq g -1, and 0.145 S cm -1, respectively. Afterwards, nanocomposite membranes based on S-PES (at the predetermined optimum sulfonation degree) containing various loading weights of organically treated montmorillonite (OMMT) were prepared via the solution intercalation technique. X-ray diffraction patterns revealed the... 

    A new approach to multi-objective optimisation method in PEM fuel cell

    , Article International Journal of Sustainable Energy ; Volume 34, Issue 5 , Jul , 2015 , Pages 283-297 ; 14786451 (ISSN) Tahmasbi, A. A ; Hoseini, A ; Roshandel, R ; Sharif University of Technology
    Taylor and Francis Ltd  2015
    This paper presents an optimisation model for polymer electrolyte membrane fuel cell system based on simultaneous power maximisation and cost minimisation. The results show that, by employing appropriate relation between the objectives, the innovative design could be proposed. Genetic algorithm is applied to solve the optimisation problem. Power maximisation results reveal that at maximum amount of power (1.95 kW), unit cost of energy is $0.64. In contrast, minimisation of cost decreases unit cost of energy to $0.33. In this condition, output power is reduced approximately to 0.93 kW. To consider both optimisation problems concurrently, weighting method and Pareto set are employed. Our... 

    Polyelectrolyte nanocomposite membranes using imidazole-functionalized nanosilica for fuel cell applications

    , Article Journal of Macromolecular Science, Part B: Physics ; Volume 54, Issue 1 , Nov , 2015 , Pages 17-31 ; 00222348 (ISSN) Tohidian, M ; Ghaffarian, S. R ; Nouri, M ; Jaafarnia, E ; Haghighi, A. H ; Sharif University of Technology
    Taylor and Francis Inc  2015
    The preparation and characterization of a new type of nanocomposite polyelectrolyte membrane, based on DuPont Nafion/imidazole-modified nanosilica (Im-Si), for direct methanol fuel cell applications is described. Related to the interactions between the protonated imidazole groups, grafted on the surface of nanosilica, and negatively charged sulfonic acid groups of Nafion, new electrostatic interactions can be formed in the interface of Nafion and Im-Si which result in both lower methanol permeability and also higher proton conductivity. Physical characteristics of these manufactured nanocomposite membranes were investigated by scanning electron microscopy, thermogravimetry analysis,... 

    Electrochemical study of Azathioprine at thin carbon nanoparticle composite film electrode

    , Article Electrochemistry Communications ; Volume 11, Issue 7 , 2009 , Pages 1425-1428 ; 13882481 (ISSN) Shahrokhian, S ; Ghalkhani, M ; Sharif University of Technology
    Thin carbon nanoparticle/Nafion film (CNP/N), as a novel electrode material, is formed on the surface of the glassy carbon electrode in a simple solvent evaporation process. The electrochemical behavior of Azathioprine (Aza) at the CNP/N-modified electrode is investigated in detail by the means of cyclic voltammetry. During the electrochemical reduction of Aza, an irreversible cathodic peak is appeared. Cyclic voltammetric studies indicated that the reduction process has an irreversible and adsorption-like behavior. The observed reduction peak is attributed to a four-electron process referring to the reduction of nitro group to the corresponding hydroxylamine. The prepared electrode showed... 

    Design and fabrication of an ubiquitous, low-cost, and wearable respiratory bio-sensor using ionic soft materials

    , Article 26th National and 4th International Iranian Conference on Biomedical Engineering, ICBME 2019, 27 November 2019 through 28 November 2019 ; 2019 , Pages 55-59 ; 9781728156637 (ISBN) Annabestani, M ; Mirzaei, I ; Esmaeili Dokht, P ; Fardmanesh, M
    Institute of Electrical and Electronics Engineers Inc  2019
    The respiratory system is a vital organ system which makes breathing and gas exchange possible for human's body. The loss of functionality in this system is due to either genetical problems or environmental issues like pollution or toxic gases which in many cases is inevitable. These circumstances may cause different respiratory diseases which may not be curable presently but their side effects can be partly controlled by careful and timely analysis improving the quality of patient's life. So, an appropriate device for conducting different analysis can be effective for people who suffer from respiratory diseases such as chronic obstructive pulmonary disease (COPD), asthma, occupational lung... 

    Effect of a monomeric sequence on the structure of hydrated Nafion in the sandwich model and solvent dynamics in nano-channels: A molecular dynamic study

    , Article Molecular Physics ; Volume 108, Issue 24 , 2010 , Pages 3393-3404 ; 00268976 (ISSN) Abroshan, H ; Akbarzadeh, H ; Taherkhani, F ; Parsafar, G ; Sharif University of Technology
    Molecular dynamics simulations are performed to obtain insight into the structural properties of hydrated Nafion using the sandwich model of the polymer membrane. It is shown that a larger distance between the sulfonate groups of a chain leads to the polymer forming a better inverted micelles structure. Water- and hydronium-polymer interfaces are investigated. Comparing our results with others indicates that, from the perspective of distance, the formation of shells of water and hydronium ions is independent of the model and monomer type, but depends on both if the coordination number is considered. The behaviour of water molecules and hydronium ions is also studied dynamically. Our survey... 

    Electrochemical determination of naltrexone on the surface of glassy carbon electrode modified with Nafion-doped carbon nanoparticles: Application to determinations in pharmaceutical and clinical preparations

    , Article Journal of Electroanalytical Chemistry ; Volume 638, Issue 2 , 2010 , Pages 212-217 ; 15726657 (ISSN) Ghorbani Bidkorbeh, F ; Shahrokhian, S ; Mohammadi, A ; Dinarvand, R ; Sharif University of Technology
    A new sensitive and selective electrochemical sensor was developed for determination of naltrexone (NAL) in pharmaceutical dosage form and human plasma. Naltrexone is an opioid antagonist which is commonly used for the treatment of narcotic addiction and alcohol dependence. A voltammetric study of naltrexone has been carried out at the surface of glassy carbon electrode (GCE) modified with Nafion-doped carbon nanoparticles (CNPs). The electrochemical oxidation of naltrexone was investigated by cyclic and differential pulse voltammetric techniques. The dependence of peak currents and potentials on pH, concentration and the potential scan rate was investigated. The electrode characterization...