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    Improved efficiency of dye-sensitized solar cells based on a single layer deposition of skein-like TiO 2 nanotubes

    , Article Journal of the American Ceramic Society ; Vol. 97, issue. 9 , 2014 , pp. 2873-2879 ; ISSN: 00027820 Mojaddami, M ; Mohammadi, M. R ; Madaah Hosseini, H. R ; Sharif University of Technology
    Abstract
    We present a new TiO2 morphology, featuring high surface area and open structure, synthesized by a two-step chemical route for the manufacture of dye-sensitized solar cells (DSSCs). This construct is sets of intertwined one-dimensional (1D) nanostructures (i.e., nanotubes), so-called skein-like nanotubes (NTs). Such morphology is produced by a combination of TiC oxidation and hydrothermal processes. The mesoporous TiO2 nanoparticles, as the product of TiC oxidation operation, is used as the precursor of hydrothermal process to grow the skein-like NTs. The effect of processing parameters of TiC oxidation and hydrothermal processes is studied. The skein-like morphology enables to eliminate the... 

    Fabrication of single-layer MS2 (M=MO, W) nanosheets using Li battery setup

    , Article Iranian Journal of Physics Research ; Volume 19, Issue 2 , 2019 , Pages 365-377 ; 16826957 (ISSN) Zirak, M ; Alehdaghi, H ; Moshfegh, A ; Sharif University of Technology
    Isfahan University of Technology  2019
    Abstract
    Lithium intercalation is a convenient method to prepare few-layer and single-layer MS2 (M=Mo, W) nanosheets. This method is, however, very time-consuming (few days) and it is difficult to control the reaction parameters. To overcome these drawbacks, we have proposed a method to use an Li battery set-up to significantly reduce the reaction time (few hours) and electrochemically intercalate lithium ions into MS2 layers in a controllable manner. Atomic force microscopy (AFM), scanning electron microscopy (SEM) and Raman spectroscopy results revealed that MoS2 and WS2 single-layer (thickness of ~ 1 nm) nanosheets with the 1T phase were prepared after intercalation in an Li battery set-up.... 

    Fabrication of single-layer MS2 (M=MO, W) nanosheets using Li battery setup

    , Article Iranian Journal of Physics Research ; Volume 19, Issue 2 , 2019 , Pages 365-377 ; 16826957 (ISSN) Zirak, M ; Alehdaghi, H ; Moshfegh, A ; Sharif University of Technology
    Isfahan University of Technology  2019
    Abstract
    Lithium intercalation is a convenient method to prepare few-layer and single-layer MS2 (M=Mo, W) nanosheets. This method is, however, very time-consuming (few days) and it is difficult to control the reaction parameters. To overcome these drawbacks, we have proposed a method to use an Li battery set-up to significantly reduce the reaction time (few hours) and electrochemically intercalate lithium ions into MS2 layers in a controllable manner. Atomic force microscopy (AFM), scanning electron microscopy (SEM) and Raman spectroscopy results revealed that MoS2 and WS2 single-layer (thickness of ~ 1 nm) nanosheets with the 1T phase were prepared after intercalation in an Li battery set-up.... 

    Applications of single-layered graphene sheets as mass sensors and atomistic dust detectors

    , Article ASME International Mechanical Engineering Congress and Exposition, IMECE 2007, Seattle, WA, 11 November 2007 through 15 November 2007 ; Volume 11 PART A , 2008 , Pages 99-104 ; 079184305X (ISBN); 9780791843055 (ISBN) Sakhaee Pour, A ; Ahmadian, M. T ; Vafai, A ; Sharif University of Technology
    2008
    Abstract
    Molecular structural mechanics is implemented to model vibrational behavior of defect free single-layered graphene sheets (SLGSs) at constant temperature. To mimic these two-dimensional layers, zigzag and armchair models with cantilever and bridge boundary conditions are adopted. Fundamental frequencies of these nano structures are calculated, and it is perceived that they are independent of the chirality and aspect ratio. Effects of point mass and atomistic dust on the fundamental frequencies are also considered in order to investigate the possibility of using SLGSs as sensors. Results of exhibit the principle frequencies are highly sensitive to the added mass in the order of 10-6fg.... 

    Peculiar transport properties in Z-shaped graphene nanoribbons: A nanoscale NOR gate

    , Article Thin Solid Films ; Volume 548 , 2013 , Pages 443-448 ; 00406090 (ISSN) Khoeini, F ; Khoeini, F ; Shokri, A ; Sharif University of Technology
    2013
    Abstract
    A nanoscale logic NOR gate has been theoretically designed by magnetic flux inputs in a Z-shaped graphene nanoribbon composed of an armchair ribbon device sandwiched between two semi-infinite metallic zigzag ribbon leads. The calculations are based on the tight-binding model and iterative Green's function method, in which the conductance as well as current-voltage characteristics of the nanosystem are calculated, numerically. We show that the current and conductance are highly sensitive to both the magnetic fluxes subject to the device and the size of the system. Our results may have important applications for building blocks in the nanoelectronic devices based on graphene nanoribbons  

    Applications of single-layered graphene sheets as mass sensors and atomistic dust detectors

    , Article Solid State Communications ; Volume 145, Issue 4 , 2008 , Pages 168-172 ; 00381098 (ISSN) Sakhaee Pour, A ; Ahmadian, M. T ; Vafai, A ; Sharif University of Technology
    2008
    Abstract
    Molecular structural mechanics is implemented to model the vibrational behavior of defect-free single-layered graphene sheets (SLGSs) at constant temperature. To mimic these two-dimensional layers, zigzag and armchair models with cantilever and bridge boundary conditions are adopted. Fundamental frequencies of these nanostructures are calculated, and it is perceived that they are independent of the chirality and aspect ratio. The effects of point mass and atomistic dust on the fundamental frequencies are also considered in order to investigate the possibility of using SLGSs as sensors. The results show that the principal frequencies are highly sensitive to an added mass of the order of 1 0-... 

    Behavior of a Single-layer Latticed Cylinder Steel Shell with a Long Span under Wind Load

    , M.Sc. Thesis Sharif University of Technology Daghestani, Shahrooz (Author) ; Khalu, Alireza (Supervisor)
    Abstract
    Single-layer steel grid shell structures are a good structural solution to new buildings by specific properties that are required by long-span structures and provide at the same time the opportunity to produce immense verity of design shapes and free form architecture; complex curved surfaces expect to be covered with low weight material. A grid shell is essentially a shell with its structure concentrated into individual linear element in relatively thin grid compared to the overall dimension of the grid shell. This research investigates single-layer grid structures with emphasis on design of load details. The application of single-layer for transparent structures enhances use of glazed... 

    Initial Blank Design of Deep Drawn Single Layer Composite parts Using Inverse Finite Element Method

    , M.Sc. Thesis Sharif University of Technology Zamanian, Hashem (Author) ; Assempour, Ahmad (Supervisor)
    Abstract

    The inverse finite element method was derived from ideal forming to predict the development blank of sheet forming process and the strain distribution according to the geometry of final product. In this project we present an inverse finite element method to obtain strain and stress distribution in final shape and design initial blank of deep drawing process. The procedure is as follows: First, strain distribution in deep drawn part is estimated by kinematics. Then by using Hill’s anisotropic plasticity and according to the associated plastic flow rule, stress distribution is obtained in deep drawn orthotropic part.Finally, initial blank is designed by considering external forces between... 

    Extraction of theoretical equation for the gamma ray buildup factor of the three-layered spherical shield

    , Article Journal of Instrumentation ; Volume 14, Issue 4 , 2019 ; 17480221 (ISSN) Rabi'ee, A ; Hosseini, S. A ; Sharif University of Technology
    Institute of Physics Publishing  2019
    Abstract
    In the previous researches, several theoretical equations were presented for calculation of buildup factor of the single layer shields. Also, the theoretical equations were offered for the two-layered shield that consist of the known materials. For other possible modes of the multi-layered shield, the buildup factor are usually calculated via experimental or simulated data. The purpose of present study is the extraction of the new theoretical equation for the gamma ray buildup factor of three-layered spherical shield made of water, concrete and iron based on the Monte Carlo calculation. To this end, the gamma ray buildup factor of the three-layered spherical shield is calculated via... 

    Applications of single-layered graphene sheets as mass sensors and atomistic dust detectors

    , Article ASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007, 11 November 2007 through 15 November 2007 ; Volume 11 , 2007 , Pages 99-104 ; 079184305X (ISBN) Sakhaee-Pour, A ; Ahmadian, M. T ; Vafai, A ; ASME ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2007
    Abstract
    Molecular structural mechanics is implemented to model vibrational behavior of defect free single-layered graphene sheets (SLGSs) at constant temperature. To mimic these two-dimensional layers, zigzag and armchair models with cantilever and bridge boundary conditions are adopted. Fundamental frequencies of these nano structures are calculated, and it is perceived that they are independent of the chirality and aspect ratio. Effects of point mass and atomistic dust on the fundamental frequencies are also considered in order to investigate the possibility of using SLGSs as sensors. Results of exhibit the principle frequencies are highly sensitive to the added mass in the order of 10-6 fg.... 

    Interlaminar hygrothermal stresses in laminated plates

    , Article International Journal of Solids and Structures ; Volume 44, Issue 25-26 , 2007 , Pages 8119-8142 ; 00207683 (ISSN) Bahrami, A ; Nosier, A ; Sharif University of Technology
    2007
    Abstract
    Within the elasticity formulation the most general displacement field for hygrothermal problems of long laminated composite plates is presented. The equivalent single-layer theories are then employed to determine the global deformation parameters appearing in the displacement fields of general cross-ply, symmetric, and antisymmetric angle-ply laminates under thermal and hygroscopic loadings. Reddy's layerwise theory is subsequently used to determine the local deformation parameters of various displacement fields. An elasticity solution is also developed in order to validate the efficiency and accuracy of the layerwise theory in predicting the interlaminar normal and shear stress... 

    Boundary-layer hygrothermal stresses in laminated, composite, circular, cylindrical shell panels

    , Article Archive of Applied Mechanics ; Volume 80, Issue 4 , 2010 , Pages 413-440 ; 09391533 (ISSN) Nosier, A ; Miri, A. K ; Sharif University of Technology
    Abstract
    Free-edge effects in laminated, circular, cylindrical shell panels subjected to hygrothermal loading are studied by utilizing displacement-based technical theories. Starting from the most general displacement field of elasticity for long, circular, cylindrical shells, appropriate reduced displacement fields are determined for laminated composite shell panels with cross-ply and antisymmetric angle-ply layups. An equivalent single-layer shell theory is used to analytically determine the constant parameters appearing in the reduced displacement fields. A layerwise shell theory is then employed to analytically determine the local displacement functions and the boundary-layer interlaminar... 

    Local impact of Stone–Wales defect on a single layer GNRFET

    , Article Physics Letters, Section A: General, Atomic and Solid State Physics ; Volume 384, Issue 7 , 2020 Shamloo, H ; Nazari, A ; Faez, R ; Shahhoseini, A ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    In this work, a new structure of single layer armchair graphene nanoribbon field effect transistor with the Stone–Wales (SW) defect (SWGNRFET) is studied. The simulations are solved with Poisson–Schrödinger equation self-consistently by using Non-Equilibrium Green Function (NEGF) and in the real space approach. The energy band structure is obtained by approximation tight-binding method. The results show that displacement of a defect in the width of the channel of the new structure is led to 50% increase in ION/IOFF ratio only by rotating of a C–C (Carbon–Carbon) bond with similar behavior. But, a remarkable increase of 300% in ION/IOFF ratio is obtained by a “dual center” defect. The results... 

    Effect of filler loading and thickness parameters on the microwave absorption characteristic of double-layered absorber based on MWCNT/BaTiO3/pitted carbonyl iron composite

    , Article Ceramics International ; Volume 47, Issue 14 , 2021 , Pages 19538-19545 ; 02728842 (ISSN) Li, Y ; Wu, X ; Chen, J ; Cao, A ; Boudaghi, R ; Akhtar, M. N ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    In this work, single- and double-layer electromagnetic wave absorbers were prepared by as-prepared MWCNTs/BaTiO3/pitted carbonyl iron composites. MWCNT/BaTiO3 (MW/BTO) was prepared via sol-gel method whereas the carbonyl iron particles (CI) were corroded via pitting corrosion method. The structural, microstructural, magnetic and microwave absorption properties of the composites were evaluated via X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA) methods. CST studio software was employed to simulate the microwave absorption characteristics of double-layer absorbers. Moreover, the effects of... 

    Inter-Laminar Stress Analysis in Boundary Layer Region of Symmetrically Laminated Plates Under Torsion

    , M.Sc. Thesis Sharif University of Technology Jamalimehr, Amin (Author) ; Nosier, Asghar (Supervisor)
    Abstract
    In the present research an analytical solution is studied for interlaminar stresses in boundary layer region of symmetric composite laminates under torsion. Based on geometrical and physical grounds the existing displacement field in literature is simplified in order to accommodate to torsion of symmetric laminates. Displacement field is divided to global and local parts. The solution procedure consists of combined equivalent single layer theories and layerwise theory of Reddy. ESL theories are more computationally economic while LWTs are considerably accurate in determining local behavior of plate. Further, based on second order shaer deformation theory and Ritz approximate variational... 

    Synthesis, Characterization and Photoelectrochemical Application of two Dimensional MoS2 and WS2 Nanosheets

    , Ph.D. Dissertation Sharif University of Technology Zirak, Mohammad (Author) ; Zaker Moshfegh, AliReza (Supervisor) ; Moradlou, Omran (Co-Advisor)
    Abstract
    In this research, Synthesis, characterization and photoelectrochemical application of two dimensional MoS2 and WS2 nanosheets have been carefully investigated. And finally, based on theoritical and experimental analysis results, the mechanisms of the observed photoelectrochemical (PEC) activities were suggested.The ab initio density functional calculations about Mo1-xWxS2 monolayer deposited over a TiO2 (110) substrate revealed a shift in band position of the Mo1-xWxS2 in favor of photoelectrochemical water splitting. Moreover, increase of W concentration in Mo1-xWxS2 could improve the charge separation and increase the effective mass ratio leading to an extension of the electron–hole... 

    Surface modification for titanium implants by hydroxyapatite nanocomposite

    , Article Caspian Journal of Internal Medicine ; Volume 3, Issue 3 , 2012 , Pages 460-465 ; 20086164 (ISSN) Family, R ; Solati Hashjin, M ; Nik, S. N ; Nemati, A ; Sharif University of Technology
    2012
    Abstract
    Background: Titanium (Ti) implants are commonly coated with hydroxyapatite (HA). However, HA has some disadvantages such as brittleness, low tensile strength and fracture toughness. It is desirable to combine the excellent mechanical properties of ZrO 2 and the chemical inertness of Al 2O 3 with respect to the purpose of this project which was coating Ti implants with HA-ZrO 2-Al 2O 3 to modify the surface of these implants by adding ZrO 2 and Al 2O 3 to HA. The purpose of this study was to evaluate the efficacy of hydroxyapatite coating nonocomposite. Methods: From September 2009 to January2011, functionally graded HA-Al 2O 3-ZrO 2 and HA coatings were applied on Ti samples. HA-Al 2O 3-ZrO... 

    Nonlinear membrane model for large amplitude vibration of single layer graphene sheets

    , Article Nanotechnology ; Volume 22, Issue 30 , June , 2011 ; 09574484 (ISSN) Mianroodi, J. R ; Niaki, S. A ; Naghdabadi, R ; Asghari, M ; Sharif University of Technology
    2011
    Abstract
    The nonlinear vibrational properties of single layer graphene sheets (SLGSs) are investigated using a membrane model. The nonlinear equation of motion is considered for the SLGSs by including the effects of stretching due to large amplitudes. The equation of motion is numerically solved utilizing the finite difference method for SLGSs with different initial and boundary conditions, sizes and pretensions. It is concluded that the nonlinear fundamental frequency of SLGSs increases by increasing the pretension and initial velocity. In addition, it is observed that an increase in the pretension weakens the effects of the initial velocity on the fundamental frequency, such that the fundamental... 

    Wrapping bacteria by graphene nanosheets for isolation from environment, reactivation by sonication, and inactivation by near-infrared irradiation

    , Article Journal of Physical Chemistry B ; Volume 115, Issue 19 , 2011 , Pages 6279-6288 ; 15206106 (ISSN) Akhavan, O ; Ghaderi, E ; Esfandiar, A ; Sharif University of Technology
    American Chemical Society  2011
    Abstract
    Bioactivity of Escherichia coli bacteria (as a simple model for microorganisms) and interaction of them with the environment were controlled by their capturing within aggregated graphene nanosheets. The oxygen-containing functional groups of chemically exfoliated single-layer graphene oxide nanosheets were reduced by melatonin as a biocompatible antioxidant. While each one of the graphene (oxide) suspension and melatonin solution did not separately show any considerable inactivation effects on the bacteria, aggregation of the sheets in the melatonin-bacterial suspension resulted in trapping the bacteria within the aggregated sheets, i.e., a kind of inactivation. The bacteria trapped within... 

    Photodegradation of graphene oxide sheets by TiO2 nanoparticles after a photocatalytic reduction

    , Article Journal of Physical Chemistry C ; Volume 114, Issue 30 , July , 2010 , Pages 12955-12959 ; 19327447 (ISSN) Akhavan, O ; Abdolahad, M ; Esfandiar, A ; Mohatashamifar, M ; Sharif University of Technology
    2010
    Abstract
    TiO2 nanoparticles were physically attached to chemically synthesized single-layer graphene oxide nanosheets deposited between Au electrodes in order to investigate the electrical, chemical, and structural properties of the TiO2/graphene oxide composition exposed to UV irradiation. X-ray photoelectron spectroscopy showed that after effective photocatalytic reduction of the graphene oxide sheets by the TiO2 nanoparticles in ethanol, the carbon content of the reduced graphene oxides gradually decreased by increasing the irradiation time, while no considerable variation was detected in the reduction level of the reduced sheets. Raman spectroscopy indicated that, at first, the photocatalytic...