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    Electrophoretic deposition of porous hydroxyapatite coatings using polytetrafluoroethylene particles as templates

    , Article Materials Science and Engineering C ; Volume 27, Issue 5-8 SPEC. ISS , 2007 , Pages 1482-1486 ; 09284931 (ISSN) Yousefpour, M ; Afshar, A ; Chen, J ; Zhang, X ; Sharif University of Technology
    The formation of macroporous bioactive hydroxyapatite(HA) coatings using polytetrafluoroethylene(PTFE) particles were studied. The porous HA coatings were prepared onto a pure titanium substrate by electrophoretic deposition(EPD) at 120 V for 1.5 min using ethanol suspensions mixture of HA (500 nm in size) and PTFE (1-3 μm in size) particles. Subsequently, the composite coatings obtained by EPD were heated at 900 °C for 60 min to disintegrate the organic PTFE particles and sinter the inorganic HA particles. The calcinations of the PTFE led to the formation of porosity in the HA coating. These results demonstrate a new method for creating porous HA coatings on titanium. © 2006 Elsevier B.V.... 

    The effect of addition of Tiron as a surfactant on the microstructure of chemically deposited zinc oxide

    , Article Materials Science and Engineering B: Solid-State Materials for Advanced Technology ; Volume 128, Issue 1-3 , 2006 , Pages 53-57 ; 09215107 (ISSN) Sadrnezhaad, S. K ; Vaezi, M. R ; Sharif University of Technology
    The effect of one of the surfactants such as Tiron, a compound based on the benzene molecule, on the morphology and chemical composition of zinc oxide deposits, produced from a zinc complex solution using two-stage chemical deposition (TSCD) technique, has been investigated. TSCD technique is a novel and simple chemical route for the deposition of ZnO film from aqueous solution. Zinc oxide films deposited on high purity alumina (HPA) as a substrate. The results show that the addition of Tiron changes the surface morphology and causes to form the fine-grained structure. With a dense and nodular-shape appearance, the film produced from the precursor of zinc complex-containing Tiron, is... 

    Multiferroic behavior of the functionalized surface of a flexible substrate by deposition of Bi2O3 and Fe2O3

    , Article Microscopy Research and Technique ; 2021 ; 1059910X (ISSN) Ramazanov, S ; Sobola, D ; Ţălu, Ş ; Orudzev, F ; Arman, A ; Kaspar, P ; Dallaev, R ; Ramazanov, G ; Sharif University of Technology
    John Wiley and Sons Inc  2021
    Thin films of bismuth and iron oxides were obtained by atomic layer deposition (ALD) on the surface of a flexible substrate poly(4,4′-oxydiphenylene-pyromellitimide) (Kapton) at a temperature of 250°C. The layer thickness was 50 nm. The samples were examined by secondary-ion mass spectrometry, and uniform distribution of elements in the film layer was observed. Surface morphology, electrical polarization, and mechanical properties were investigated by atomic force microscope, piezoelectric force microscopy, and force modulation microscopy. The values of current in the near-surface layer varied in the range of ±80 pA when a potential of 5 V was applied. Chemical analysis was performed by... 

    Co surface modification by bias sputtering in Cu/Co(Vb)/NiO/ Si(100) magnetic multilayer structures

    , Article Physica Status Solidi C: Conferences ; Volume 1, Issue 7 , 2004 , Pages 1744-1747 ; 16101634 (ISSN) Moshfegh, A. Z ; Sangpour, P ; Sharif University of Technology
    To investigate the Ta/Co/Cu/Co/NiO/Si(100) spin valve structure, fabrication and characterization of the Cu/Co/NiO/Si(100) system was studied for further understanding the structure. The system was grown by employing combinative DC sputtering-evaporation technique. Nickel oxide with a thickness of about 30 nm was deposited on Si(100) substrate using thermal evaporation technique.The cobalt film, then, with a thickness of about 3 nm was grown by DC sputtering under various applied negative bias voltages ranging from 0 to - 80 V. The optimum bias voltage (Vb = -60 V) for the growth of Co layer was determined by atomic force microscopy (AFM), four-point probe sheet measurement (Rs) and scanning... 

    Characterization of a transition-edge bolometer made of YBCO thin films prepared by nonfluorine metal-organic deposition

    , Article IEEE Transactions on Applied Superconductivity ; Volume 21, Issue 6 , 2011 , Pages 3587-3591 ; 10518223 (ISSN) Hosseini, M ; Moftakharzadeh, A ; Kokabi, A ; Vesaghi, M. A ; Kinder, H ; Fardmanesh, M ; Sharif University of Technology
    We present the results of a bolometric transition-edge sensor made of a high-Tc superconductor YBCO thin film prepared by fluorine-free metal-organic deposition. The structure of the films was characterized by X-ray diffraction and scanning electron microscopy, and the superconducting properties were determined by R-T measurements. The applicability of the resulting film as an infrared sensor is reported here. The optical response in the range of near infrared and the noise characteristics of the patterned bolometer are measured and analyzed. The dependence of device sensitivity on the bias current and modulation frequency is also investigated. As it is presented in this paper, the results... 

    The laser-assisted field effect transistor gas sensor based on morphological zinc-excited tin-doped in2o3 nanowires

    , Article Surface Review and Letters ; Volume 24, Issue 8 , 2017 ; 0218625X (ISSN) Shariati, M ; Khosravinejad, F ; Sharif University of Technology
    The gas nanosensor of indium oxide nanowires in laser assisted approach, doped with tin and zinc for gas sensing and 1D growth purposes respectively, was reported. The nanowires were very sensitive to H2S gas in low concentration of 20 ppb gas at room temperature. The fast dynamic intensive and sensitive response to gas was in a few seconds with an on/off sensitivity ratio of around 10. The square cross-section indium oxide nanowires were fabricated through physical vapor deposition (PVD) mechanism and annealing approach. The field emission scanning electron microscopy (FESEM) observations indicated that the annealing temperature was vital in nanostructures' morphology. The fabricated... 

    Synthesis and Characterization of Cu2ZnSnS4 (CZTS)Thin Films Prepared by Pulsed Laser Deposition Technique

    , M.Sc. Thesis Sharif University of Technology Dabbagh, Mohammad Mahdi (Author) ; Mahdavi, Mohammad (Supervisor)
    The Cu2ZnSnS4 (CZTS) quaternary compound, with suitable optical and electrical properties, is one of the most interesting materials for absorber layer of thin film solar cell. Since all constituents of CZTS, are abundant in earth’s crust and non-toxic, it is a proper replacement for the materials like CdTe and CuInSe2. The CZTS pellet was synthesized by the solid-state reaction and deposited on soda lime glass substrates by pulsed laser deposition (PLD) method. PLD technique has the advantages of offering stoichiometric preservation during the materials transformation from target to substrate and good crystallinity due to the highly energetic species. CZTS has was deposited in order to... 

    Investigation of Asphaltene Electro-deposition Under Dynamic Flow Conditions

    , M.Sc. Thesis Sharif University of Technology Azari, Vahid (Author) ; Taghikhani, Vahid (Supervisor) ; Ayatollahi, Shahabodin (Supervisor)
    Asphaltene, known as the heaviest and the most polar component of the crude oil, can precipitate because of the changes in the fluid condition such as pressure, temperature and composition. Asphaltene deposition causes major problems during oil production, in the form of fluid viscosity changes, wellbore damage and fouling in pipelines. The remediation of these problems is very expensive and needs to halt down the crude oil production. The use of electric field has been proposed recently as clean and cheap technique that could also be applied during the production period. In this work, the effect of electric potential on asphaltene precipitation in both static and dynamic modes has been... 

    An Estimation Model for Computation and Control of Trajectory Coverage Error in Additive Manufacturing

    , M.Sc. Thesis Sharif University of Technology Zargar, Farinaz (Author) ; Houshmand, Mahmood (Supervisor)
    During 1980s Additive Manufacturing technologies for the purpose of prototyping with fast and less expensive, under the name of Rapid Prototyping was invented. But nowadays under the vast progress made in this field, it possesses a notable place in different industries such as automobile manufacturing, aerospace, architecture, medicine and so on for part manufacturing. In all AM machines, the CAD model design part is manufactured by adding layered to each other. In this research, at first by explaining manufacturing process and current different technologies, the place of this manufacturing process in today and future industry, is analyzed. For discussing replacement of this method instead... 

    Dynamic Modeling and Experimental Study of Asphaltene Deposition in Wellbore Considering Mechanism of Precipitation, Aggregation and Deposition

    , Ph.D. Dissertation Sharif University of Technology Salehzadeh, Marziyeh (Author) ; Ghotbi, Cyrus (Supervisor) ; Dabir, Bahram (Co-Supervisor) ; Taghikhani, Vahid (Co-Supervisor)
    Efforts to identify, predict, and resolve problems linked to asphaltenes and flow assurance have resulted in the development of numerous laboratory and modelling techniques. However, there has been little research on the molecular structure of asphaltenes and how it relates to solubility, stability, aggregation, and deposition behavior. Not only was a thorough structural analysis of asphaltene extracted from three samples of light, medium, and heavy oil performed in this study, but medium oil asphaltene was also fractionated into three sub-fractions based on solubility, with minimum, medium, and maximum solubility, and each subfraction was subjected to a structural analysis. All asphaltene... 

    A core scale investigation of Asphaltene precipitation during simultaneous injection of oil and CO2: An experimental and simulation study

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Vol. 36, issue. 10 , Dec , 2014 , pp. 1077-1092 ; ISSN: 15567036 Bagherzadeh, H ; Rashtchian, D ; Ghazanfari, M. H ; Kharrat, R ; Sharif University of Technology
    Although CO2 injection significantly increases the amount of oil recovered, it can cause asphaltene deposition in oil reservoirs. Asphaltene deposition leads to formation damage, in which treatment is a costly and problematic operation. In this work, impact of asphaltene precipitation and deposition during CO2 injection are investigated for recombined oil both in sandstone and carbonate core samples through dynamic flow experiments. Injection of oil and CO2 was performed simultaneously. Then, pressure drops along the core were recorded continuously to estimate permeability reductions during the experiments. Online viscosity of injected fluid was measured by a designed capillary viscometer.... 

    Preparation and corrosion resistance of pulse electrodeposited Zn and Zn-SiC nanocomposite coatings

    , Article Applied Surface Science ; Vol. 300 , May , 2014 , pp. 1-7 ; ISSN: 01694332 Sajjadnejad, M ; Mozafari, A ; Omidvar, H ; Javanbakht, M ; Sharif University of Technology
    Pure Zn and Zn matrix composite coatings containing nano-sized SiC particles with an average size of 50 nm were prepared from the zinc sulfate bath. The effects of the pulse frequency, maximum current density and duty cycle on the amount of particles embedded were examined. Electron microscopic studies revealed that the coating morphology was modified by the presence of SiC nanoparticles. In the presence of SiC nanoparticles deposit grows in outgrowth mode resulting in a very rough and porous microstructure. However, at very low and very high duty cycles a smooth and pore free microstructure was obtained. Corrosion resistance properties of the coatings were studied using potentiodynamic... 

    Effect of resins on asphaltene deposition and the changes of surface properties at different pressures: A microstructure study

    , Article Energy and Fuels ; Vol. 28, issue. 4 , April , 2014 , pp. 2415-2421 ; ISSN: 08870624 Soorghali, F ; Zolghadr, A ; Ayatollahi, S ; Sharif University of Technology
    Asphaltene deposition has hindered oil production from asphaltenic oil reservoirs through deposition in reservoir rock and surface facilities. This paper investigates the effect of resin on asphaltene deposition at different pressures. To investigate the asphaltene deposition in the presence of resins at reservoir temperature and different pressures, a pressure, volume, and temperature (PVT) visual cell was designed. A high-resolution microscope and image processing software were used to detect and determine the amount of deposited asphaltene as well as its size distribution at different conditions. Two types of Iranian crude oils with different potential of deposition (low and high) were... 

    Optimization of sputtering parameters for the deposition of low resistivity indium tin oxide thin films

    , Article Acta Metallurgica Sinica (English Letters) ; Vol. 27, issue. 2 , Apr , 2014 , p. 324-330 Yasrebi, N ; Bagheri, B ; Yazdanfar, P ; Rashidian, B ; Sasanpour, P ; Sharif University of Technology
    Indium tin oxide (ITO) thin films have been deposited using RF sputtering technique at different pressures, RF powers, and substrate temperatures. Variations in surface morphology, optical properties, and film resistances were measured and analyzed. It is shown that a very low value of sheet resistance (1.96 ω/sq.) can be achieved with suitable arrangement of the deposition experiments. First, at constant RF power, deposition at different pressure values is done, and the condition for achieving minimum sheet resistance (26.43 ω/sq.) is found. In the next step, different values of RF powers are tried, while keeping the pressure fixed on the previously found minimum point (1-2 Pa). Finally,... 

    SAFT model for upstream asphaltene applications

    , Article Fluid Phase Equilibria ; Volume 359 , December , 2013 , Pages 2-16 ; 03783812 (ISSN) Panuganti, S. R ; Tavakkoli, M ; Vargas, F. M ; Gonzalez, D. L ; Chapman, W. G ; Sharif University of Technology
    The increasing incidence of flow assurance problems caused by asphaltene deposition during oil production has motivated the development of numerous theoretical models and experimental methods to analyze this complex phenomenon. Even more challenging are the prediction of the occurrence and the magnitude of asphaltene deposition. It is well accepted that precipitation of asphaltene is a necessary condition for deposition. Hence, a significant amount of work has been devoted to the understanding of the conditions at which asphaltene precipitate from the crude oil. Although, several models seem to work well for correlating available data of onsets of asphaltene precipitation, they usually lack... 

    Synthesis of sodium tungsten oxide nano-thick plates

    , Article Materials Letters ; Volume 82 , September , 2012 , Pages 214-216 ; 0167577X (ISSN) Garavand, N. T ; Mahdavi, S. M ; Irajizad, A ; Ahadi, K ; Sharif University of Technology
    Elsevier  2012
    In this letter a simple procedure to synthesize sodium tungsten oxide nano-thick plates from WO 3 films has been reported. WO 3 films were grown by pulsed-laser deposition method and then heat treated at temperatures up to 560 °C and times up to 120 min. Slide glass was used as both substrate and sodium source simultaneously. XRD analysis revealed presence of an amorphous structure for as-deposited WO 3 films. On the other hand, XRD showed formation of a monoclinic WO 3 structure with annealing in lower temperatures and a triclinic Na 0.5WO 3.25 structure with annealing at higher temperatures. Intensity of the triclinic phase peaks enhanced drastically by rising annealing temperature and... 

    Electronic structure and morphological study of BaTiO 3 film grown by pulsed-laser deposition

    , Article Materials Letters ; Volume 72 , April , 2012 , Pages 107-109 ; 0167577X (ISSN) Ahadi, K ; Mahdavi, S. M ; Nemati, A ; Tabesh, M ; Ranjbar, M ; Sharif University of Technology
    The morphological characteristics and electronic structure of the BaTiO 3 films grown by pulsed-laser deposition technique have been investigated. AFM and FE-SEM images reveal columnar growth characteristic of these films. Utilizing spectrophotometer, optical band gap of the films were reckoned to be about 3.76 eV. Both dα/dE and PL vs. E plots reveal numerous luminance states in the gap. Despite the presence of many luminance faults in the gap, cations manage to preserve their electronic states  

    Fabrication of HAp-8YSZ composite layer on Ti/TiO2 nanoporous substrate by EPD/MAO method

    , Article Materials Letters ; Volume 65, Issue 23-24 , 2011 , Pages 3421-3423 ; 0167577X (ISSN) Hekmatfar, M ; Moshayedi, Sh ; Ghaffari, S. A ; Rezaei, H. R ; Golestani Fard, F ; Sharif University of Technology
    Zirconia/Hydroxyapatite composites containing 20-50 wt.% 8YSZ were prepared on Ti/TiO2 substrates by electrophoretic deposition (EPD)/micro-arc oxidation (MAO) process. Titania, as an inner layer, was grown on the Ti plates using MAO treatment in order to form a strong join between substrate and HAp. These composites were produced by EPD in ethanol containing ZrO2/HAp particles at 50, 100 and 150 V in 1 min. Asprepared samples were sintered at 900, 1100 and 1300 °C. HAp, β-TCP, CaZrO3 phases were identified using X-ray diffractometry analysis (XRD). Scanning electron microscopy (SEM) utilized to study the surface morphology indicated a crack free microstructure at 1300 °C  

    Effects of native and non-native resins on asphaltene deposition and the change of surface topography at different pressures: an experimental investigation

    , Article Energy and Fuels ; Volume 29, Issue 9 , July , 2015 , Pages 5487-5494 ; 08870624 (ISSN) Soorghali, F ; Zolghadr, A ; Ayatollahi, S ; Sharif University of Technology
    American Chemical Society  2015
    Asphaltene deposition during oil production and transportation causes extensive damage to reservoirs and wellhead equipment. In this study, the effects of native and non-native resins as well as those of their mixtures on the asphaltene deposition process are investigated. A novel pressure, volume, and temperature (PVT) visual cell is used to check the effect of resin on asphaltene deposition at different pressures and reservoir temperatures. Two Iranian crude oil samples with different potentials of asphaltene deposition (low and high) were used in these tests. During depressurizing in the presence of native and non-native resins, the amount of asphaltene deposited was measured. To monitor... 

    Studies on the catalyst preparation methods and kinetic behavior of supported cobalt catalysts for the complete oxidation of cyclohexane

    , Article Reaction Kinetics, Mechanisms and Catalysis ; Volume 114, Issue 2 , Jan , 2015 , Pages 611-628 ; 18785190 (ISSN) Zabihi, M ; Khorasheh, F ; Shayegan, J ; Sharif University of Technology
    Springer Netherlands  2015
    Low cost dispersed supported cobalt oxide nanocatalysts on activated carbon (AC) were prepared by two different methods: (1) combined impregnation and deposition–precipitation (IMP-DP) and (2) heterogeneous deposition–precipitation (HDP). XRD, TEM, FESEM, BET and Boehm techniques were used for the characterization of the support and the catalysts. Characterization analyses indicated the negative effect of the wet impregnation method on the IMP-DP technique for the preparation of catalysts for the total oxidation of cyclohexane in air. The catalysts prepared by HDP and IMP-DP methods were found to have significant differences in oxidation activity, morphology, particle size, and shape of...