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    Morphology of nanodroplets on structured surfaces

    , Article Journal of Physics D: Applied Physics ; Volume 46, Issue 21 , May , 2013 ; 00223727 (ISSN) Vahid, A ; Moosavi, A ; Sharif University of Technology
    We report different morphologies of nanodroplets over various topographical features of the supporting substrates. The effects of different parameters such as the profile of the disjoining pressure, droplet size and the geometrical parameters are studied and discussed. Also, the effects of a coating layer on the surface of the substrate are determined. It is demonstrated that the nanodroplets at some positions are not stable and gradually move to more stable positions so that the system has less energy. For grooves this results in a series of morphology diagrams of the nanodroplets over the grooves as a function of the grooves' width and the liquid volume  

    Graphene nanogrids for selective and fast osteogenic differentiation of human mesenchymal stem cells

    , Article Carbon ; Volume 59 , 2013 , Pages 200-211 ; 00086223 (ISSN) Akhavan, O ; Ghaderi, E ; Shahsavar, M ; Sharif University of Technology
    Graphene nanogrids (fabricated by graphene nanoribbons obtained through oxidative unzipping of multi-walled carbon nanotubes) were used as two-dimensional selective templates for accelerated differentiation of human mesenchymal stem cells (hMSCs), isolated from umbilical cord blood, into osteogenic lineage. The biocompatible and hydrophilic graphene nanogrids showed high actin cytoskeleton proliferations coinciding with patterns of the nanogrids. The amounts of proliferations were found slightly better than proliferation on hydrophilic graphene oxide (GO) sheets, and significantly higher than non-uniform proliferations on hydrophobic reduced graphene oxide (rGO) sheets and... 

    Differentiation of human neural stem cells into neural networks on graphene nanogrids

    , Article Journal of Materials Chemistry B ; Volume 1, Issue 45 , 2013 , Pages 6291-6301 ; 20507518 (ISSN) Akhavan, O ; Ghaderi, E ; Sharif University of Technology
    Graphene nanogrids (crossed graphene nanoribbons synthesized by the oxidative unzipping of multi-walled carbon nanotubes) on a SiO2 matrix containing TiO2 nanoparticles (NPs) were applied as a photocatalytic stimulator in the accelerated differentiation of human neural stem cells (hNSCs) into two-dimensional neural networks. The hydrophilic graphene nanogrids exhibited patterned proliferations of hNSCs (consistent with patterns of the nanogrids), in contrast with the usual random growths occurring on quartz substrates. The number of cell nuclei differentiated on reduced graphene oxide nanoribbon (rGONR) grid/TiO2 NPs/SiO2 increased ∼5.9 and 26.8 fold compared to the number of cells on quartz... 

    Surface micromorphology and fractal geometry of Co/CP/X (X = Cu, Ti, SM and Ni) nanoflake electrocatalysts

    , Article RSC Advances ; Volume 6, Issue 32 , 2016 , Pages 27228-27234 ; 20462069 (ISSN) Ţəlu, Ş ; Solaymani, S ; Bramowicz, M ; Naseri, N ; Kulesza, S ; Ghaderi, A ; Sharif University of Technology
    Royal Society of Chemistry  2016
    This paper analyses the three-dimensional (3-D) surface texture of Co/CP/X (X = Cu, Ti, SM and Ni, CP: carbonaceous paste) nanoflakes prepared electrochemically using a conventional three electrode system. The surface chemical composition of the samples was investigated by X-ray photoelectron spectroscopy (XPS). Surface images were recorded using scanning electron microscopy (SEM) and analyzed by means of the fractal geometry. Statistical, fractal and functional surface properties of the prepared samples were computed. The statistical functions applied to the SEM data were employed in order to characterise the surfaces topographically (in amplitude, spatial distribution and pattern of... 

    Evaluation of the topographical surface changes of silicon wafers after annealing and plasma cleaning

    , Article Silicon ; Volume 12, Issue 11 , 2020 , Pages 2563-2570 Stach, S ; Ţălu, Ş ; Dallaev, R ; Arman, A ; Sobola, D ; Salerno, M ; Sharif University of Technology
    Springer Science+Business Media B.V  2020
    Purpose: The morphological stability of silicon single crystal wafers was investigated, after performing cleaning surface treatments based on moderate temperature annealing and plasma sputtering. Methods: The wafer surfaces were measured by Tapping mode atomic force microscopy in air, before and after the different treatments. The 3D images were segmented by watershed algorithm identifying the local peaks, and the stereometric parameters were extracted thereof. The analysis of variance allowed to better assess the statistically significant differences. Results: All the resulting quantities were critically discussed. It appeared that the different cleaning treatments affected differently the... 

    Stellar occultations enable milliarcsecond astrometry for Trans-Neptunian objects and Centaurs

    , Article Astronomy and Astrophysics ; Volume 644 , 2020 Rommel, F. L ; Braga Ribas, F ; Desmars, J ; Camargo, J. I. B ; Ortiz, J. L ; Sicardy, B ; Vieira-Martins, R ; Assafin, M ; Santos-Sanz, P ; Duffard, R ; Fernández Valenzuela, E ; Lecacheux, J ; Morgado, B. E ; Benedetti Rossi, G ; Gomes-Júnior, A. R ; Pereira, C. L ; Herald, D ; Hanna, W ; Bradshaw, J ; Morales, N ; Brimacombe, J ; Burtovoi, A ; Carruthers, T ; De Barros, J. R ; Fiori, M ; Gilmore, A ; Hooper, D ; Hornoch, K ; Jacques, C ; Janik, T ; Kerr, S ; Kilmartin, P ; Winkel, J.M ; Naletto, G ; Nardiello, D ; Nascimbeni, V ; Newman, J ; Ossola, A ; Pál, A ; Pimentel, E ; Pravec, P ; Sposetti, S ; Stechina, A ; Szakáts, R ; Ueno, Y ; Zampieri, L ; Broughton, J ; Dunham, J. B ; Dunham, D.W ; Gault, D ; Hayamizu, T ; Hosoi, K ; Jehin, E ; Jones, R ; Kitazaki, K ; Komž Ík, R ; Marciniak, A ; Maury, A ; Mikuž, H ; Nosworthy, P ; Fábrega Polleri, J ; Rahvar, S ; Sfair, R ; Siqueira, P. B ; Snodgrass, C ; Sogorb, P ; Tomioka, H ; Tregloan Reed, J ; Winter, O. C ; Sharif University of Technology
    EDP Sciences  2020
    Context. Trans-Neptunian objects (TNOs) and Centaurs are remnants of our planetary system formation, and their physical properties have invaluable information for evolutionary theories. Stellar occultation is a ground-based method for studying these distant small bodies and has presented exciting results. These observations can provide precise profiles of the involved body, allowing an accurate determination of its size and shape. Aims. The goal is to show that even single-chord detections of TNOs allow us to measure their milliarcsecond astrometric positions in the reference frame of the Gaia second data release (DR2). Accurate ephemerides can then be generated, allowing predictions of... 

    Wear characteristics of aluminum matrix nanocomposites with Ce-TZP/Al 2O3 nanocomposite produced by powder metallurgy at different sintering temperatures

    , Article TMS Annual Meeting, San Antonio, TX ; 2013 , Pages 1103-1110 ; 9781118605813 (ISBN) Soltani, N ; ABahrami ; Pech-Canul, M. I ; Sharif University of Technology
    In this work the effects of sintering temperature on the hardness, friction and wear characteristics of Al-10Ce-TZP/Al2O3 composites have been investigated. Aluminum and Ce-TZP/Al2O3 nanocomposite were selected as raw materials. Ce-TZP/Al2O3 nanocomposites were synthesized by the aqueous combustion method. 7 wt. % 10Ce-TZP/Al2O3 composites in the form of cylindrical samples were prepared at the sintering temperatures of 400, 450 and 500°C under an applied pressure of 600 MPa for 60 min. Wear tests were carried out using the pin-on-disk method under normal loads of 10 and 20 Kgf at constant sliding velocity of 0.25 m/s. The surfaces of the worn nanocomposite were examined by scanning electron... 

    Thin liquid film flow over substrates with two topographical features

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 87, Issue 2 , 2013 ; 15393755 (ISSN) Mazloomi, A ; Moosavi, A ; Sharif University of Technology
    A multicomponent lattice Boltzmann scheme is used to investigate the surface coating of substrates with two topographical features by a gravity-driven thin liquid film. The considered topographies are U- and V-shaped grooves and mounds. For the case of substrates with two grooves, our results indicate that for each of the grooves there is a critical width such that if the groove width is larger than the critical width, the groove can be coated successfully. The critical width of each groove depends on the capillary number, the contact angle, the geometry, and the depth of that groove. The second groove critical width depends on, in addition, the geometry and the depth of the first groove;... 

    Engineering of mature human induced pluripotent stem cell-derived cardiomyocytes using substrates with multiscale topography

    , Article Advanced Functional Materials ; Volume 28, Issue 19 , 2018 ; 1616301X (ISSN) Pour Shahid Saeed Abadi, P ; Garbern, J. C ; Behzadi, S ; Hill, M. J ; Tresback, J. S ; Heydari, T ; Ejtehadi, M. R ; Ahmed, N ; Copley, E ; Aghaverdi, H ; Lee, R. T ; Farokhzad, O. C ; Mahmoudi, M ; Sharif University of Technology
    Wiley-VCH Verlag  2018
    Producing mature and functional cardiomyocytes (CMs) by in vitro differentiation of induced pluripotent stem cells (iPSCs) using only biochemical cues is challenging. To mimic the biophysical and biomechanical complexity of the native in vivo environment during the differentiation and maturation process, polydimethylsiloxane substrates with 3D topography at the micrometer and sub-micrometer levels are developed and used as cell-culture substrates. The results show that while cylindrical patterns on the substrates resembling mature CMs enhance the maturation of iPSC-derived CMs, sub-micrometer-level topographical features derived by imprinting primary human CMs further accelerate both the... 

    Stereometric analysis of TiO2 thin films deposited by electron beam ion assisted

    , Article Optical and Quantum Electronics ; Volume 52, Issue 5 , 2020 Shakoury, R ; Arman, A ; Ţălu, Ş ; Dastan, D ; Luna, C ; Rezaee, S ; Sharif University of Technology
    Springer  2020
    The micromorphology and semiconductor properties of TiO2 thin films growth using different ion beam energies have been finely analyzed using atomic force microscopy (AFM), ultra-violet visible (UV–visible) spectroscopy and stereometric analysis. The AFM measurements and surface stereometric analysis are essential for the accurate characterization of the 3-D surface topographic features and allow the determination of the 3-D surface texture parameters that influence the optical properties of the material. The samples were divided into four groups to discuss the obtained results, according to the ion beam energy applied in the sample preparation. The results obtained from experimental...