Search for: surface-treatment
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    “ Nano Oxide Layer Forming on the Surface of Porous Nitinol Shape Memory Alloy for Improving Surface Properties “

    , M.Sc. Thesis Sharif University of Technology Fattahzadeh, Mehrdad (Author) ; Sadrnejhad, Khatiboleslam (Supervisor)
    In this project ,it has been done different surface treatment on 6 samples of nitinol with 40 % prosity,three of them are anodized by H2SO4 ,Hf, Acetic acid, one of them is treated with plasma spray with TIO2 powder, one of them is putted in the furnace at 700 degrees for an hour, and the last one is bare ; Moreover, these treated samples are putted in Simulated body fluid for 16 days . After this period of time, we analyzed the results. Then the cell adhesion amount of osteo blast cells (MG 63) is measured to these samples by immersing them for 3 days in these cells.The results are investigated by SEM ,XRD(X pertpro produced by Panalitical), XRF(530-XRF-01), AAS( AA240), Roughness measuring... 

    Effective surface modification of MnFe2O4@SiO2@PMIDA magnetic nanoparticles for rapid and high-density antibody immobilization

    , Article Applied Surface Science ; Volume 426 , 2017 , Pages 1023-1029 ; 01694332 (ISSN) Rashid, Z ; Soleimani, M ; Ghahremanzadeh, R ; Vossoughi, M ; Esmaeili, E ; Sharif University of Technology
    The present study is aimed at the synthesis of MnFe2O4@SiO2@PMIDA in terms of highly efficient sensing platform for anti-prostate specific membrane antigen (PSMA) immobilization. Superparamagnetic manganese ferrite nanoparticles were synthesized following co-precipitation method and then SiO2 shell was coated on the magnetic core with tetraethyl orthosilicate (TEOS) through a silanization reaction to prevent oxidation, agglomeration and, increase the density of OH groups on the surface of MnFe2O4. Subsequently, MnFe2O4@SiO2@PMIDA obtained as a result of the reaction between N-(phosphonomethyl)iminodiacetic acid (PMIDA) and MnFe2O4@SiO2. The reactive carboxyl groups on the surface of magnetic... 

    Fabrication and characterization of low-cost, bead-free, durable and hydrophobic electrospun membrane for 3D cell culture

    , Article Biomedical Microdevices ; Volume 19, Issue 4 , 2017 ; 13872176 (ISSN) Moghadas, H ; Saidi, M. S ; Kashaninejad, N ; Kiyoumarsioskouei, A ; Trung Nguyen, N ; Sharif University of Technology
    This paper reports the fabrication of electrospun polydimethylsiloxane (PDMS) membranes/scaffolds that are suitable for three-dimensional (3D) cell culture. Through modification the ratio between PDMS and polymethylmethacrylate (PMMA) as carrier polymer, we report the possibility of increasing PDMS weight ratio of up to 6 for electrospinning. Increasing the PDMS content increases the fiber diameter, the pore size, and the hydrophobicity. To our best knowledge, this is the first report describing beads-free, durable and portable electrospun membrane with maximum content of PDMS suitable for cell culture applications. To show the proof-of-concept, we successfully cultured epithelial lung... 

    Smart and fragrant garment via surface modification of cotton fabric with cinnamon oil/stimuli responsive PNIPAAm/chitosan nano hydrogels

    , Article IEEE Transactions on Nanobioscience ; Volume 16, Issue 6 , 2017 , Pages 455-462 ; 15361241 (ISSN) Bashari, A ; Hemmatinejad, N ; Pourjavadi, A ; Sharif University of Technology
    This paper deals with obtaining aromatherapic textiles via applying stimuli-responsive poly N-isopropyl acryl amide (PNIPAAm) chitosan (PNCS) nano hydrogels containing cinnamon oil on cotton fabric and looks into the treated fabric characteristics as an antibacterial and temperaturepH responsive fabric. The semi-batch surfactant-free dispersion polymerization method was proposed to the synthesis of PNCS nano particles. The incorporation of modified β -cyclodextrin ( β-CD) into the PNCS nanohydrogel was performed in order to prepare a hydrophobic(cinnamon oil) carrier embedded in stimuli-responsive nanohydrogel. The β -CD postloading process of cinnamon oil in to the hydrogel nano particles... 

    Melt compounding of thermoplastic polyurethanes incorporating 1D and 2D carbon nanofillers

    , Article Polymer - Plastics Technology and Engineering ; Volume 56, Issue 7 , 2017 , Pages 732-743 ; 03602559 (ISSN) Yuan, D ; Pedrazzoli, D ; Pircheraghi, G ; Manas Zloczower, I ; Sharif University of Technology
    Taylor and Francis Inc  2017
    Thermoplastic polyurethane nanocomposites incorporating carbon nanotubes and graphene nanoplatelets were prepared through melt blending and compression molding, and the compounding process was optimized taking into account the different physical properties of one-dimensional carbon nanotubes and two-dimensional graphene nanoplatelets. Filler dispersion was further improved in the case of carbon nanotubes by noncovalent surface modification using a specific surfactant. The well-dispersed nanofillers favored enhanced phase separation in the thermoplastic polyurethane, leading to a better microstructure, which is able to improve the load transfer and maximize the tensile and viscoelastic... 

    Surface and mechanical properties of modified porous titanium scaffold

    , Article Surface and Coatings Technology ; Volume 315 , 2017 , Pages 61-66 ; 02578972 (ISSN) Khodaei, M ; Valanezhad, A ; Watanabe, I ; Yousefi, R ; Sharif University of Technology
    The bioinertness makes surface treatments essential to improve the bioactivity of porous titanium scaffold, and surface treatment might affect their mechanical properties. So finding an optimum condition lying between bioactivity and mechanical properties seems to be curial. In this research, the effect of the time of the thermal oxidation at 600 °C on apatite formation and mechanical properties of the porous titanium scaffold was studied. The results of thin film X-ray diffraction and Raman spectroscopy indicated that the surface of heat treated samples up to 480 min was mainly covered by rutile. Also, wettability measurement and in vitro apatite formation ability assessment indicated that... 

    The investigation of laser shock peening effects on corrosion and hardness properties of ANSI 316L stainless steel

    , Article International Journal of Advanced Manufacturing Technology ; Volume 88, Issue 5-8 , 2017 , Pages 1557-1565 ; 02683768 (ISSN) Ebrahimi, M ; Amini, S ; Mahdavi, S. M ; Sharif University of Technology
    Springer London  2017
    Laser shock peening (LSP) is known as a post processing surface treatment which can improve the mechanical properties of some materials. Shock waves are generated by confining the laser-induced plasma to cause a large pressure shock wave over a significant surface area. In the present study, effects of LSP on the electrochemical corrosion and micro hardness properties of 316L stainless steel alloy were investigated by changing the laser parameters such as the laser spot size, the average number of impacts, and the laser intensity. Since laser parameters do not cover the desired region of LSP, we have to use the proper design of experiment method, in which the D-optimal design of MATLAB was... 

    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... 

    Communication - Co-electrodeposition of Ni/SiO2(CH2)3SH composite: Modified Guglielmi’s model and mechanism of nucleation

    , Article Journal of the Electrochemical Society ; Volume 164, Issue 13 , 2017 , Pages E472-E474 ; 00134651 (ISSN) Fazlolahzadeh, O ; Rouhollahi, A ; Dolati, A ; Ghahramanifard, F ; Sharif University of Technology
    Electrochemical Society Inc  2017
    This work studies the influence of surface modification of silica nanoparticles by mercaptopropyl trimethoxysilane on silica weight percent in Ni coating during electrodeposition. Results showed SiO2(CH2)3SH particles were embedded in the Ni coating up to 11%. Also, modified Guglielmi’s model and mechanicsm of nucleation of Ni-SiO2(CH2)3SH composite were studied. © 2017 The Electrochemical Society. All rights reserved  

    Fouling control mechanism by optimum ozone addition in submerged membrane bioreactors treating synthetic wastewater

    , Article Journal of Environmental Chemical Engineering ; Volume 6, Issue 6 , 2018 , Pages 7294-7301 ; 22133437 (ISSN) Mashayekhi, F ; Hazrati, H ; Shayegan, J ; Sharif University of Technology
    In this paper, the effect of ozone on membrane fouling of membrane bioreactor (MBR) systems was investigated. Sludge specification such as soluble microbial product (SMP), extracellular polymeric substance (EPS), viscosity, particle size distribution (PSD), microscopic observations and sludge volume index (SVI) in presence of ozone were determined. Further, EPS, Fourier-transform infrared (FTIR) analysis, excitation-emission matrix (EEM) fluorescence spectroscopy, and gel permission chromatography (GPC) are considered to determine cake layer characteristics. The results indicated COD removal did not show significant difference with ozonation. Ozone also increases the particle size and... 

    Fabrication and characterization of graphene-based carbon hollow spheres for encapsulation of organic corrosion inhibitors

    , Article Chemical Engineering Journal ; Volume 352 , 2018 , Pages 909-922 ; 13858947 (ISSN) Haddadi, S. A ; Ramazani, S. A. A ; Mahdavian, M ; Taheri, P ; Mol, J. M. C ; Sharif University of Technology
    Elsevier B.V  2018
    In this work, we synthesized carbon hollow spheres (CHSs) using the silica templating method, encapsulated 2-mercaptobenzimidazole (MBI) inhibitor in the CHSs and evaluated their corrosion inhibition performance upon exposure of mild steel to a saline solution containing the released inhibitor. The effects of silica template surface modification on the CHS structure was evaluated, while the structure and morphology of the synthesized CHS was analyzed using field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), Raman spectroscopy and X-ray diffraction (XRD) spectroscopy. Furthermore, thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy... 

    Graphene oxide in generation of nanobubbles using controllable microvortices of jet flows

    , Article Carbon ; Volume 138 , 2018 , Pages 8-17 ; 00086223 (ISSN) Jannesari, M ; Akhavan, O ; Madaah Hosseini, H. R ; Sharif University of Technology
    Elsevier Ltd  2018
    Spontaneous generation of nanobubbles (NBs) was developed by using a controllable platform of superfast microvortices, based on turbulent jet flows in the presence of graphene oxide (GO) sheets. Very high energy dissipation rates through discharging warm water into cold N2 aqueous solutions resulted in creation of micro/submicro-vortices. Shear stresses in these domains generated gas local supersaturations, leading to the formation of high concentration (∼109 mL−1) of stable NBs. Introducing GO sheets into the microvortex system resulted in effective manipulation of NBs by providing energetically favorable sites for prompt heterogeneous nucleation as well as stronger shear rate fluctuations.... 

    Free radical graft polymerization of 2-hydroxyethyl methacrylate and acrylic acid on the polysulfone membrane surface through circulation of reaction media to improve its performance and hemocompatibility properties

    , Article Journal of Membrane Science ; Volume 564 , 2018 , Pages 762-772 ; 03767388 (ISSN) Nouri Goushki, M ; Mousavi, S. A ; Abdekhodaie, M. J ; Sadeghi, M ; Sharif University of Technology
    Elsevier B.V  2018
    In this study, a new facile and cost effective method is used to modify polysulfone membrane surface in order to improve the hydrophilicity, antifouling, and blood compatibility. This modification was performed by adding two functional monomers on the dialysis membrane. Polysulfone (PSF) membranes containing polyvinylpyrrolidone were prepared via phase inversion technique. In the next step, free radical polymerization combined with surface polymerization was used to introduce acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) onto the polysulfone membrane surface via circulation of initiator and monomer solutions across the membrane surface, respectively. Various monomer concentrations... 

    Surface modification of a hole transporting layer for an efficient perovskite solar cell with an enhanced fill factor and stability

    , Article Molecular Systems Design and Engineering ; Volume 3, Issue 5 , 2018 , Pages 717-722 ; 20589689 (ISSN) Tavakoli, M. M ; Tavakoli, R ; Prochowicz, D ; Yadav, P ; Saliba, M ; Sharif University of Technology
    The improvement of the quality of the hole transporting layer (HTL) plays a key role in the fabrication of highly efficient and stable perovskite solar cells (PSCs). Here, we used rubrene as a surface treatment agent on top of a spiro HTL. We found that rubrene can cover the pinholes of the spiro layer and provide an excellent contact layer for planar PSCs. Based on this modification, mobile gold ions from the metal electrode are prevented from diffusing through the HTL hindering the degradation of PSCs. The optimized device shows a maximum power conversion efficiency (PCE) of 19.87% and a 79% fill factor (FF), which are higher than the 17.98% PCE and 72% FF of the reference device. In... 

    Developing an Analytical Model for Predicting the Residual Stresses Induced by Shot Peening with Considering the Effect of Initial Surface Treatment

    , Ph.D. Dissertation Sharif University of Technology Sherafatnia, Khalil (Author) ; Farrahi, Gholam Hossein (Supervisor) ; Mahmoudi, Amir Hossein (Co-Supervisor)
    Shot peening is a cold-working process commonly used in industry to improve the fatigue performance, stress corrosion resistance and surface nano-crystallization of metallic parts. This process extends fatigue life via two mechanisms: Preventing the crack growth due to compressive residual stresses and, preventing the crack initiation because of increased material hardness. These mechanisms are the results of the bombardment of the component's surface with small spherical particles. In this research, an analytical model is developed for estimating the residual stress distribution induced by shot peening process. The modifications of the developed analytical model are related to... 

    Direct growth of metal-organic frameworks thin film arrays on glassy carbon electrode based on rapid conversion step mediated by copper clusters and hydroxide nanotubes for fabrication of a high performance non-enzymatic glucose sensing platform

    , Article Biosensors and Bioelectronics ; Volume 112 , 2018 , Pages 100-107 ; 09565663 (ISSN) Shahrokhian, S ; Khaki Sanati, E ; Hosseini, H ; Sharif University of Technology
    Elsevier Ltd  2018
    The direct growth of self-supported metal-organic frameworks (MOFs) thin film can be considered as an effective strategy for fabrication of the advanced modified electrodes in sensors and biosensor applications. However, most of the fabricated MOFs-based sensors suffer from some drawbacks such as time consuming for synthesis of MOF and electrode making, need of a binder or an additive layer, need of expensive equipment and use of hazardous solvents. Here, a novel free-standing MOFs-based modified electrode was fabricated by the rapid direct growth of MOFs on the surface of the glassy carbon electrode (GCE). In this method, direct growth of MOFs was occurred by the formation of vertically... 

    Enhanced Electronic Properties in Mesoporous TiO2 Via Passivation Treatment in Perovskite Solar Cells

    , M.Sc. Thesis Sharif University of Technology Azadi, Moloud (Author) ; Mohammadi, Mohammad Reza (Supervisor)
    Perovskite solar cells are the new generation of solar cells, and are mainly introduced in two types of structures.1) planer and 2) mesoscopic structure. The difference between these two structures derives from the absence of mesoporous layer in the planer structures. The mesoporous layer acts as an electron transporting layer, and is mainly a titanium dioxide semiconductor. To apply the mesoporous layer, the preparation of the TiO2 paste is needed.The synthesis of titanium dioxide nanopowder for the preparation of TiO2 paste requires high temperature heat treatment and is not desirable in terms of energy consumption.Another weakness of this layer is the presence of surface defects, which... 

    Inhibitory effects of functionalized indium doped ZnO nanoparticles on algal growth for preservation of adobe mud and earthen-made artworks under humid conditions

    , Article International Biodeterioration and Biodegradation ; Volume 127 , Febraury , 2018 , Pages 209-216 ; 09648305 (ISSN) Shariati, M ; Mallakin, A ; Malekmohammady, F ; Khosravi Nejad, F ; Sharif University of Technology
    Elsevier Ltd  2018
    In this article, indium doped ZnO nanoparticles (alloy nanoparticles) were investigated as inhibitors against algae growth on adobe mud and earthen artworks for surface preservation from destruction caused by micro-organisms under humid conditions, through surface modification and activation run off. Nanoparticles (NPs) were fabricated by physical vapor deposition (PVD) growth mechanism. The fabricated NPs were approximately 20 nm in size. The Chlorella vulgaris and Scenedesmus quadricauda were tested by application of indium doped ZnO nanoparticles (In/ZnO NPs) as inhibitors. As concentrations of NPs increased, the negative impacts of NPs on the algal growth were enhanced and physical... 

    Effect of initial surface treatment on shot peening residual stress field: analytical approach with experimental verification

    , Article International Journal of Mechanical Sciences ; Volume 137 , 2018 , Pages 171-181 ; 00207403 (ISSN) Sherafatnia, K ; Farrahi, G. H ; Mahmoudi, A. H ; Sharif University of Technology
    Elsevier Ltd  2018
    Shot peening is the most common surface treatment employed to enhance the fatigue performance of structural metallic materials and often carried out after other surface treatments. This paper mainly focuses on the effects of initial conditions of surface such as initial stress filed and hardness profile on shot peening residual stress field. The residual stress distribution induced by shot peening is obtained using Hertzian contact theory and elastic–plastic evaluation after yielding occurred during impingement and rebound of shots. Elastic plastic calculations are performed using different hardening models considering Bauschinger effect. The present model is able to predict redistribution... 

    Modelling of conventional and severe shot peening influence on properties of high carbon steel via artificial neural network

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 31, Issue 2 , 2018 , Pages 382-393 ; 1728144X (ISSN) Maleki, E ; Farrahi, G. H ; Sharif University of Technology
    Materials and Energy Research Center  2018
    Shot peening (SP), as one of the severe plastic deformation (SPD) methods is employed for surface modification of the engineering components by improving the metallurgical and mechanical properties. Furthermore, artificial neural network (ANN) has been widely used in different science and engineering problems for predicting and optimizing in the last decade. In the present study, effects of conventional shot peening (CSP) and severe shot peening (SSP) on properties of AISI 1060 high carbon steel were modelled and compared via ANN. In order to networks training, the back propagation (BP) error algorithm is developed and data of experimental tests results are employed. Experimental data...