Search for: chemical-modification
0.006 seconds
Total 47 records

    Methanol electrooxidation on a nickel electrode modified by nickel-dimethylglyoxime complex formed by electrochemical synthesis

    , Article Journal of Electroanalytical Chemistry ; Volume 588, Issue 1 , 2006 , Pages 155-160 ; 15726657 (ISSN) Nozad Golikand, A ; Asgari, M ; Ghannadi Maragheh, M ; Shahrokhian, S ; Sharif University of Technology
    Elsevier  2006
    Nickel-dimethylglyoxime complex (NiDMG) modified nickel electrode (Ni/NiDMG) showed a catalytic activity towards methanol oxidation in NaOH solution. The modified electrode prepared by the dimethylglyoxime anodic deposition on Ni electrode in the solution containing 0.20 mol L-1 NH4Cl + NH4OH (pH 9.50) and 1.0 × 10-4 mol L-1 dimethylglyoxime. The modified electrode conditioned by potential recycling in a potential range of 100-700 mV (vs. SCE) by cyclic voltammetry in alkaline medium (0.10 M NaOH). The results show that the NiODMG film on the electrode behaves as an efficient catalyst for the electrooxidation of methanol in alkaline medium via Ni(III) species formed on the electrode with the... 

    Quantitative risk assessment for accidental release of ethylene oxide from purification column of an ethylene oxide production unit

    , Article CHISA 2006 - 17th International Congress of Chemical and Process Engineering, Prague, 27 August 2006 through 31 August 2006 ; 2006 ; 8086059456 (ISBN); 9788086059457 (ISBN) Abdolhamidzadeh, B ; Hashemi, V ; Rashtchian, D ; Sharif University of Technology
    This paper outlines a quantitative risk assessment for an 110,000 ton/day ethylene oxide production plant in Iran. After a complete and detailed hazard identification study, done by HAZOP method, the purification column was found to be one of the most hazardous sections in this plant. As ethylene oxide with high concentration and inventory is present there. Fault tree analysis (FTA) technique has been used to identify the basic events responsible for top event occurrence and also calculation of top event frequency of occurrence. Human error has been calculated numerically and probability of human error has been estimated. Failure rate data were collected referring to several sources and... 

    The Pr and oxygen correlation in the GdPr123 system

    , Article Modern Physics Letters B ; Volume 16, Issue 25 , 2002 , Pages 943-953 ; 02179849 (ISSN) Khosroabadi, H ; Daadmehr, V ; Akhavan, M ; Sharif University of Technology
    We prepared single-phase polycrystalline Gd1-xPrx Ba2Cu3O7-δ samples with x = 0, 0.10, 0.15, and 0.20. The deoxygenation process of these samples was performed by an annealing method. Electrical resistivity measurements revealed depression of the transition temperature with the increase of x and δ. We calculated the hole concentration in the CuO2 plane for different values of x and δ. A linear dependence of transition temperature and hole concentration in the CuO2 plane was found as a function of 2δ + x. It is proposed that a combination of the localization and filling of holes should be considered as the effective mechanisms for the appearance of the Pr anomaly in HTSCs  

    Chemical Adjustment of Membrane Surface to Reduce Fouling in Membrane Bioreactors

    , M.Sc. Thesis Sharif University of Technology Vaghar-Mousavi, Danial (Author) ; Bastani, Dariush (Supervisor) ; Mousavi, Abbas (Supervisor)
    In this study, modification of Polyvinylidene fluoride membrane in order to reduce membrane fouling in membrane bioreactors is investiged. To achieve this goal, chemical modification and grafting methods were used. Initially, by chemical modification, the reaction was made to make hydroxyl groups on the membrane surface. The hydroxyl functional groups were used as a site for connecting of subsequent monomers. Finally, the lysozyme enzyme was used as the main modifier to improve the hydrophilicity and antibacterial properties of the membrane surface. To evaluate the performance of the modified membrane in comparison with the pristine membrane, different tests, such as water contact angle... 

    Pulsed laser deposition of W-V-O composite films: preparation, characterization and gasochromic studies

    , Article Solar Energy Materials and Solar Cells ; Volume 92, Issue 8 , 2008 , Pages 878-883 ; 09270248 (ISSN) Ranjbar, M ; Mahdavi, S. M ; Iraji zad, A ; Sharif University of Technology
    Modified tungsten oxide films by vanadium oxide provide neutrally coloring electrochromic electrodes for smart windows technology. In this study W-V-O mixed oxide films were fabricated by Nd:YAG pulsed laser deposition (PLD), λ=1064 nm, from mixed pressed powders of (WO3)1-x(V2O5)x, x=0, 0.09, 0.17, 0.23, 0.29 and 0.33, at 13.3 Pa oxygen partial pressure and 200 °C temperature on glass substrates. X-ray photoelectron spectroscopy (XPS) revealed V5+, V4+, W6+ and W5+ surface oxide states, where the ratio of W5+/W6+ enhances by the amount of vanadium in the films. Surface morphology was studied by scanning electron microscope (SEM) and optical properties by transmission-reflection spectra.... 

    Cobalt salophen-modified carbon-paste electrode incorporating a cationic surfactant for simultaneous voltammetric detection of ascorbic acid and dopamine

    , Article Sensors and Actuators, B: Chemical ; Volume 121, Issue 2 , 2007 , Pages 530-537 ; 09254005 (ISSN) Shahrokhian, S ; Zare Mehrjardi, H. R ; Sharif University of Technology
    A carbon-paste electrode (CPE) is modified by incorporating cobalt-5-nitrosalophen (CoNSal) and tetraoctylammonium bromide (TOAB). The mechanism of electrocatalytic oxidation of dopamine (DA) and ascorbic acid (AA) at the surface of the CoNSal-modified CPE containing various percents of TOAB is thoroughly investigated by cyclic and differential pulse voltammetry. In solutions of pH 5.0, in which all studies are performed, DA exists as the positively charged species whereas AA is mainly as the neutral form. Therefore, the favorable ionic interaction (electrostatic repulsion) between the cationic form of DA and the cationic surfactant (TOA+) caused increasing the overvoltage for DA and... 

    N-benzyl-DABCO-tribromide as an efficient and mild reagent for deprotection of dithioacetals

    , Article Synthetic Communications ; Volume 36, Issue 8 , 2006 , Pages 1093-1096 ; 00397911 (ISSN) Moghaddam, F. M ; Boeini, H. Z ; Zargarani, D ; Bardajee, G. R ; Sharif University of Technology
    N-Benzyl-DABCO-ammonium tribromide was found to be an efficient and recyclable reagent for the deprotection of dithioacetals in dichloromethane/ methanol at room temperature. The reaction can be performed cleanly, in short time, and in high yield. Copyright © Taylor & Francis Group, LLC  

    FEM study of the second stage creep behavior of Al6061/SiC metal matrix composite

    , Article Computational Materials Science ; Volume 34, Issue 2 , 2005 , Pages 140-150 ; 09270256 (ISSN) Mondali, M ; Abedian, A ; Adibnazari, S ; Sharif University of Technology
    Prediction of the creep behavior of metal matrix whiskers reinforced composites is the subject of many analytical and experimental research works. However, application of the FEM modeling to this area has not been so successful. The present research work highlights the shortcomings of the previous FEM studies and combines the analytical findings with the power of FEM modeling. More specifically, the fiber/matrix debonding parameter ξ is incorporated into the modeling. In contrary to the analytical results, it is shown that the value of ξ could only change in the range of zero to 0.5. The results indicate that the exponential creep law along with the modified ξ-σ relationship, and the newly... 

    Synthesis of new electromagnetic nanocomposite based on modified Fe3O4 nanoparticles with enhanced magnetic, conductive, and catalytic properties

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 65, Issue 8 , 2016 , Pages 384-390 ; 00914037 (ISSN) Pourjavadi, A ; Doroudian, M ; Afshar Saveh, Z ; Doulabi, M ; Sharif University of Technology
    Taylor and Francis Inc  2016
    A new method for the fabrication of an electromagnetic nanocomposite based on Fe3O4 and polyaniline (PANI) is offered. The authors focused on improvement of the physical and electromagnetic properties of the nanocomposite using a new synthetic method. Supermagnetic Fe3O4 nanoparticles were synthesized through coprecipitation method. As a chemical modification, the third generation of poly (amidoamine) dendrimer was grafted on the surface of the nanoparticles. PANI was grafted from -NH2 functional groups of dendrimer via in situ polymerization of aniline. Finally, Au nanoparticles were loaded on the nanocomposite and its catalytic activity for reduction reactions was studied  

    Stimulus-responsive liposomes as smart nanoplatforms for drug delivery applications

    , Article Nanotechnology Reviews ; 2017 ; 21919089 (ISSN) Sahandi Zangabad, P ; Mirkiani, S ; Shahsavari, S ; Masoudi, B ; Masroor, M ; Hamed, H ; Jafari, Z ; Davatgaran Taghipour, Y ; Hashemi, H ; Karimi, M ; Hamblin, M. R ; Sharif University of Technology
    Liposomes are known to be promising nanoparticles (NPs) for drug delivery applications. Among different types of self-assembled NPs, liposomes stand out for their non-toxic nature, and their possession of dual hydrophilic-hydrophobic domains. Advantages of liposomes include the ability to solubilize hydrophobic drugs, the ability to incorporate different hydrophilic and lipophilic drugs at the same time, lessening the exposure of host organs to potentially toxic drugs and allowing modification of the surface by a variety of different chemical groups. This modification of the surface, or of the individual constituents, may be used to achieve two important goals. Firstly, ligands for active... 

    Stimulus-responsive liposomes as smart nanoplatforms for drug delivery applications

    , Article Nanotechnology Reviews ; Volume 7, Issue 1 , 2018 , Pages 95-122 ; 21919089 (ISSN) Sahandi Zangabad, P ; Mirkiani, S ; Shahsavari, S ; Masoudi, B ; Masroor, M ; Hamed, H ; Jafari, Z ; Davatgaran Taghipour, Y ; Hashemi, H ; Karimi, M ; Hamblin, M. R ; Sharif University of Technology
    Walter de Gruyter GmbH  2018
    Liposomes are known to be promising nanoparticles (NPs) for drug delivery applications. Among the different types of self-assembled NPs, liposomes stand out for their non-toxic nature and their possession of dual hydrophilic-hydrophobic domains. The advantages of liposomes include the ability to solubilize hydrophobic drugs, the ability to incorporate different hydrophilic and lipophilic drugs at the same time, lessening the exposure of host organs to potentially toxic drugs and allowing modification of the surface by a variety of different chemical groups. This modification of the surface, or of the individual constituents, may be used to achieve two important goals. First, ligands for... 

    Modification of isotactic polypropylene by the free-radical grafting of 1,1,1-trimethylolpropane trimethacrylate

    , Article Journal of Applied Polymer Science ; Volume 104, Issue 2 , 2007 , Pages 950-958 ; 00218995 (ISSN) Mousavi Saghandikolaei, S. A ; Frounchi, M ; Dadbin, S ; Augier, S ; Passaglia, E ; Ciardelli, F ; Sharif University of Technology
    The chemical modification of isotactic polypropylene was performed by the free-radical-promoted grafting of 1,1,1-trimethylolpropane trimethacrylate (TMPTMA) in the presence of dicumyl peroxide (DCP) as the initiator. The reaction was carried out both in a batch internal mixer and in a corotating twin-screw extruder; the effects of the peroxide and monomer concentrations on the extent of modification in terms of the grafting efficiency and polymer chain structure variations were investigated. The modified samples were characterized with Fourier transform infrared to determine the structure of the grafted groups and the degree of functionalization, with gel permeation chromatography and the... 

    Chemical modification of the electrode surface by composites of Ag Nanoparticle Decorated on Multi Walled Carbon Nanotube; Application to Investigate the Electrochemical behavior and Determination of Risperidone and Isoxsuprine drugs

    , M.Sc. Thesis Sharif University of Technology Hafezi Kahnamoui, Mohammad (Author) ; Shahrokhian, Saeed (Supervisor)
    Nowadays, electrochemical sensors have numerous benefits, including simplicity,low cost, high selectivity and high sensitivity as an efficient and useful tool in various fields such as the environment, disease diagnostics, medical and medical surveillance, and Anti-terrorism security systems have become the focus of attention in the field of analytical measurements. In the meantime, carbon nanostructures and metal nanoparticles have been considered as suitable alternatives in order to improve their surface properties due to their unique electronic properties and mechanical and chemical stability. Since the determination of trace amounts of pharmaceutical and biological compounds is very... 

    Simulation of blood oxygenation in capillary membrane oxygenators using modified sulfite solution

    , Article Biophysical Chemistry ; Vol. 195, issue , Dec , 2014 , p. 8-15 Tabesh, H ; Amoabediny, G ; Rasouli, A ; Ramedani, A ; Poorkhalil, A ; Kashefi, A ; Mottaghy, K ; Sharif University of Technology
    Blood oxygenation is the main performance characteristic of capillary membrane oxygenators (CMOs). Handling of natural blood in in vitro investigations of CMOs is quite complex and time-consuming. Since the conventional blood analog fluids (e.g. water/glycerol) lack a substance with an affinity to capture oxygen comparable to hemoglobin's affinity, in this study a novel approach using modified sulfite solution is proposed to address this challenge. The solution comprises sodium sulfite as a component, simulating the role of hemoglobin in blood oxygenation. This approach is validated by OTR (oxygen transfer rate) measured using native porcine blood, in two types of commercially available... 

    Chemically modified organic/inorganic nanoporous composite particles for the adsorption of reactive black 5 from aqueous solution

    , Article Reactive and Functional Polymers ; Volume 86 , 2015 , Pages 7-15 ; 13815148 (ISSN) Nematollahzadeh, A ; Shojaei, A ; Karimi, M ; Sharif University of Technology
    Elsevier  2015
    In the present work, we report a chemically modified polyacrylamide/silica nanoporous composite adsorbent for the removal of reactive black 5 (RB5) azo dye from aqueous solutions. The composite adsorbent was synthesized in a packed bed and modified by ethylenediamine (EDA). The adsorbent was characterized by Fourier transformation infrared (FT-IR), thermogravimetric analysis (TGA), thermoporometry, Brunauer, Emmett and Teller (BET) method and scanning electron microscopy (SEM). Mechanical stability of the adsorbent was examined in a packed bed by following the back-pressure of the column. Pore diameter of the composite adsorbent in dry and wet states was estimated to be about 18.71 nm and... 

    Use of the freely-swimming, Serratia marcescens bacteria to enhance mixing in microfluidic systems

    , Article ASME 2009 International Mechanical Engineering Congress and Exposition, 13 November 2009 through 19 November 2009 ; Volume 12, Issue PART A , 2010 , Pages 463-467 ; 9780791843857 (ISBN) Peysepar, M ; Shafii, M. B ; Rasoulian, R ; Jamalifar, H ; Fazeli, M. R ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME) 
    Mixing has become a challenge in micro-fluidic systems because of the low Reynolds number in micro-channels. The method which is implemented in this paper is to use freely-swimming bacteria to enhance the mixing process. Accordingly, the Serratia marcescens bacteria were used for this matter. The mixing performance of the system is quantified by measuring the diffusion rate of Rhodamine B in a particular section of a channel connected to a chamber with varying Rhodamine B concentration. The concentration of Rhodamine B was measured using the Laser Induced Fluorescence (LIF) technique. The channel is in the form of a pipe and is closed on the extending side. In this paper, it is demonstrated... 

    Regioselective diversification of 2,1-borazaronaphthalenes: unlocking isosteric space via C-H activation

    , Article Journal of Organic Chemistry ; Volume 82, Issue 15 , 2017 , Pages 8072-8084 ; 00223263 (ISSN) Davies, G. H. M ; Jouffroy, M ; Sherafat, F ; Saeednia, B ; Howshall, C ; Molander, G. A ; Sharif University of Technology
    Methods for the regioselective C-H borylation and subsequent cross-coupling of the 2,1-borazaronaphthalene core are reported. Azaborines are dependent on B-N/C=C isosterism when employed in strategies for developing diverse heterocyclic scaffolds. Although 2,1-borazaronaphthalene is closely related to naphthalene in terms of structure, the argument is made that the former has electronic similarities to indole. Based on that premise, iridium-mediated C-H activation has enabled facile installation of a versatile, nucleophilic coupling handle at a previously inaccessible site of 2,1-borazaronaphthalenes. A variety of substituted 2,1-borazaronaphthalene cores can be successfully borylated and... 

    Enhancement of surface properties and performance of reverse osmosis membranes after surface modification: a review

    , Article Desalination ; Volume 420 , 2017 , Pages 330-383 ; 00119164 (ISSN) Asadollahi, M ; Bastani, D ; Musavi, S. A ; Sharif University of Technology
    Reverse osmosis (RO) membrane process has become the most promising technology for desalination to produce purified water. Among numerous polymeric materials used to fabricate RO membranes, aromatic polyamide thin film composite (TFC) membranes are dominant in commercial RO membrane processes because of their high salt rejection and water permeability as well as their excellent chemical, thermal, and mechanical stability. However, the major hindrance to the effective application of polyamide TFC RO membranes is membrane fouling. Furthermore, polyamide TFC RO membranes have limited stability to chlorine, which is commonly used as disinfect to control membrane biofouling. These two factors... 

    Monodentate palladium(0)-[60]fullerene complexes of diphosphine ligands as efficient and sustainable nanocatalysts for the Mizoroki-Heck coupling reaction of aryl chlorides

    , Article New Journal of Chemistry ; Volume 41, Issue 18 , 2017 , Pages 9701-9709 ; 11440546 (ISSN) Sabounchei, S. J ; Hosseinzadeh, M ; Zarepour Jevinani, M ; Ghanbari, B ; Sharif University of Technology
    Royal Society of Chemistry  2017
    Two mononuclear coordination complexes of fullerene[60] with Pd(dba)2 (dba = dibenzylideneacetone), [(η2-C60)Pd(Ph2P(CH2)2PPh2C(H)C(O)R)2] (R = C10H7 (1), C6H4Cl (2)), have been prepared using a simple procedure to explore new directions in palladium catalysis and nanocarbon chemistry. The palladium(0)-[60]fullerene complexes incorporating unsymmetrical phosphorus ylides have been characterized by 1H, 13C and 31P NMR spectroscopic methods and other conventional techniques such as IR, TGA, SEM, ICP-OES, EDX and TEM analysis. Attributed to the enhanced dispersity and uniform size of the Pd nanoparticles with phosphine-functionalized fullerenes, the prepared catalysts exhibited comparable... 

    The role of oxygen defects in magnetic properties of gamma-irradiated reduced graphene oxide

    , Article Journal of Alloys and Compounds ; Volume 784 , 2019 , Pages 134-148 ; 09258388 (ISSN) Enayati, M ; Nemati, A ; Zarrabi, A ; Shokrgozar, M. A ; Sharif University of Technology
    Elsevier Ltd  2019
    Recently, graphene oxide and its unconventional magnetism have attracted much interest due to their novel applications in spintronics, memory chips and theranostics. Owing to the excellent biocompatibility, cellular uptake, bio-conjugation possibilities, flexible chemical modification and characteristic broad-wavelength absorbance, graphene oxide and its derivatives have been utilized as contrast agents for various imaging modalities such as photoluminescence, photoacoustic or ultrasound. Despite their suitable applications in bioimaging and due to lack of magnetic moment, graphene oxide cannot confer magnetic resonance imaging contrast without incorporating the magnetic component. Such...