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    Transfer of d -level quantum states through spin chains by random swapping

    , Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 75, Issue 2 , 2007 ; 10502947 (ISSN) Bayat, A ; Karimipour, V ; Sharif University of Technology
    We generalize an already proposed protocol for quantum state transfer to spin chains of arbitrary spin. An arbitrary unknown d -level state is transferred through a chain with rather good fidelity by the natural dynamics of the chain. We compare the performance of this protocol for various values of d. A by-product of our study is a much simpler method for picking up the state at the destination as compared with the one proposed previously. We also discuss entanglement distribution through such chains and show that the quality of entanglement transition increases with the number of levels d. © 2007 The American Physical Society  

    Ba@Pr or Pr@Ba in R123 HTSC - To be or not to be SC

    , Article Physica Status Solidi (B) Basic Research ; Volume 241, Issue 6 , 2004 , Pages 1242-1250 ; 03701972 (ISSN) Akhavan, M ; Sharif University of Technology
    In spite of the vast amount of experimental and theoretical knowledge accumulated in HTSC, the nature of the interaction driving charge carriers to form Cooper pairs below Tc is still unknown. To elucidate the controversial insulating/SC Pr123, the substitution of Pr at Ba site (Pr@Ba) with Ba at Pr site (Ba@Pr) in R123 is compared and reviewed. This might shed some light on the microscopic origin of HTSC. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim  

    Synthesis and Study of Electron Transport through a Self-Assembled Monolayer of Thiol-End-Functionalized Tetraphenylporphyrines and Metalo-Tetraphenylporphyrines and Electrochemical Analysis of Dopamine and Ascorbic Acid with this SAMs

    , M.Sc. Thesis Sharif University of Technology Sanaei, Mahsa (Author) ; Mohammadi Boghaei, Davar (Supervisor)
    Self-Assembled Monolayer (SAM) is the first step in all surface engineering and assembly processes. It is used in sensor fabrication, memories and molecular recognition and optoelectronic devises as an active surface for patterning and chemical architecting of solid substrates. Tetraphenyl porphyrins because of their high stability and uniqe electronic and optic properties, that comes from their conjugate π electrons, easily can be used in these monolayers. Moreover they have a wide application because of their ability for coordination with metals and accepting substituents with electron donating and withdrawing properties. Electron transport through these layars which attach to the surface... 

    Experimental Study of Microbial Fuel Cell

    , M.Sc. Thesis Sharif University of Technology Khazraei Vizhemehr, Ali (Author) ; Kariminia, Hamid Reza (Supervisor) ; Yaghmaei, Soheila (Supervisor)
    Annually, global energy demand increases. Although oil products meet much part of this demand currently, soaring sustainable supply difficulties and pollution global warming related problems considered as main barriers against reviving alternative energy technologies. To make fundamental changes in global economy, it is necessary to change human lifestyle radically. Such changes will affect all life levels. Fuel sells are a possible (and partial) solution. Fuel cells with proton exchange membrane have better performance in low temperature and more yield compared to other kinds of fuel cells. Microbial Fuel Cells present the newest way for electricity production (from Biomass). A well plan... 

    Investigation of Electron Transport and Scattering Effect of Dye Sensitized Solar Cells by the Using Titania Nano Particles and Perovskite Structures ( ATiO3)

    , M.Sc. Thesis Sharif University of Technology Ayneband, Samaneh (Author) ; Mohammadi, Mohammad Reza (Supervisor)
    Morphology, microstructure, phase composition and arrangement modes of the photoanode electrode are the most important parameters which affect the photovoltaic properties of dye-sentisized solar cells (DSSCs). In most DSSCs the scattering layer has been used to improve their efficiency. In addition, there are different techniques to improve the electron transport using different morphologies of titania such as one-dimensional nanostructures. In this research, the effect of peroskite structures on electron transport and scattering effect is investigated. Using sol-gel process, the compositions will be produced which have special morphology and appropriate band gap in spite of pure titania.... 

    Theoretical investigation of the hydrogen abstraction reaction of the OH radical with CH3CHF2 (HFC152-a): A dual level direct density functional theory dynamics study

    , Article Journal of Physical Chemistry A ; Volume 109, Issue 36 , 2005 , Pages 8158-8167 ; 10895639 (ISSN) Taghikhani, M ; Parsafar, G. A ; Sabzyan, H ; Sharif University of Technology
    The hydrogen abstraction reaction of the OH radical with CH 3CHF2 (HFC152-a) has been studied theoretically over a wide temperature range, 200-3000 K. Two different reactive sites of the molecule, CH3 and CHF2 groups have been investigated precisely, and results confirm that CHF2 position of the molecule is a highly reactive site. In this study, three recently developed hybrid density functional theories, namely, MPWB1K, MPW1B95, and MPW1K, are used. The MPWB1K/6-31+G(d,p) method gives the best result for kinetic calculations, including barrier heights, reaction path information and geometry of transition state structures and other stationary points. To refine the barrier height of each... 

    Electrical transport properties of thin Ni films subjected to an array of nanomagnets

    , Article 2005 5th IEEE Conference on Nanotechnology, Nagoya, 11 July 2005 through 15 July 2005 ; Volume 1 , 2005 , Pages 15-18 ; 0780391993 (ISBN); 9780780391994 (ISBN) Nasirpouri, F ; Nogaret, A ; Atkinson, D ; Ghorbani, M ; Iraji Zad, A ; Sharif University of Technology
    IEEE Computer Society  2005
    We report on magnetoresistance measurements in thin nickel films modulated by a periodic magnetic field emanating from micromagnetic arrays fabricated at the film surface. By increasing the strength of the magnetic potential using nickel and dysprosium micromagnets, we are able to quench the anisotropic magnetoresistance (AMR). We also observe mesoscopic magnetoresistance fluctuations, which possibly are related to the magnetic potential and size effects. ©2005 IEEE  

    Stimuli-responsive emissive behavior of 1- and 1,3-connectivities in azulene-based imine ligands: Cycloplatination and Pt-Tl dative bond formation

    , Article Dalton Transactions ; Volume 46, Issue 34 , 2017 , Pages 11327-11334 ; 14779226 (ISSN) Jamali, S ; Mousavi, N. A ; Bagherzadeh, M ; Kia, R ; Samouei, H ; Sharif University of Technology
    Royal Society of Chemistry  2017
    The preparation of two new azulene-based imine ligands N-(2,6-diisopropylphenyl)-6-tBu-1-azulenylmethaneimine, 3, and N-(2,6-diisopropylphenyl)-6-tBu-3-(2,6-diisopropylphenyliminomethyl)-1-azulenylmethaneimine, 4, is described. These imine ligands display stimuli responsive emissive behavior and their fluorescence can be switched on and off by protonation and neutralization with trifluoroacetic acid and trimethylamine, respectively. The cyclometalation of the monoimine ligand by platinum gave the cyclometalated complex [PtMe(SMe2)(3′)], 5, (where the prime denotes the cyclometalated ligand 3). The reaction of 5 with TlPF6 yields the trinuclear bent Pt2Tl complex {[PtMe(SMe2)(3′)]2(μ-Tl)}PF6,... 

    Kinetics of glucose isomerization to fructose by immobilized glucose isomerase (Sweetzyme IT)

    , Article Industrial and Engineering Chemistry Research ; Volume 48, Issue 7 , 2009 , Pages 3271-3278 ; 08885885 (ISSN) Molaei Dehkordi, A ; Shoai Tehrany, M ; Safari, I ; Sharif University of Technology
    We present the kinetic parameters and equilibrium constant of the enzymatic glucose-fructose isomerization reaction with an immobilized glucose isomerase (IGI), Sweetzyme IT, using a batch stirred-tank reactor following the procedure developed by Dehkordi et al. (AIChE J. 2008, 54, 1333). The model predictions were compared with the experimental data and fair agreements were found. The influence of temperature on the equilibrium constant and kinetic parameters of glucose to fructose isomerization reaction was investigated. In addition, the frequency factors and the activation energies were determined by using Arrhenius-like expressions. Furthermore, correlations were found for the maximum... 

    The Effect of Surface, Morphology, and Composition of Semiconductor Layer on the Back Reaction of Electrons in Dye Sensithized Solar Cells:Theoritical and Experimental Investigation

    , Ph.D. Dissertation Sharif University of Technology Pazoki, Meysam (Author) ; Taghavinia, Nima (Supervisor) ; Nafari, Nasser (Supervisor)
    This thesis deals with a theoretical and experimental investigation of different approaches for reduction of electronic recombination in the semiconductor/Dye interface of dye sensitized solar cells (DSSC) including dye coverage, core-shell structures and energy level distributions. Interface of ZnO/TiO2 in the core-shell structure have been studied by density functional theory and the energy level distribution of surface atoms, recombination and Fermi level changes, open circuit voltage and surface dipole distributions have been discussed.
    The presence of TiO2 shell increases the ZnO surface dipole moment, and shifts the ZnO conduction and valence bands to higher energies. Also, it... 

    Theoretical investigation on antioxidant activity of bromophenols from the marine red alga Rhodomela confervoides: H-atom vs electron transfer mechanism

    , Article Journal of Agricultural and Food Chemistry ; Volume 61, Issue 7 , 2013 , Pages 1534-1541 ; 00218561 (ISSN) Javan, A. J ; Javan, M. J ; Tehrani, Z. A ; Sharif University of Technology
    Bromophenols are known as antioxidant radical scavengers for some biomolecules such as those in marine red alga. Full understanding of the role played by bromophenols requires detailed knowledge of the radical scavenging activities in probable pathways, a focus of ongoing research. To gain detailed insight into two suggested pathways, H-atom transfer and electron transfer, theoretical studies employing first principle quantum mechanical calculations have been carried out on selected bromophenols. Detailed investigation of the aforementioned routes revealed that upon H-atom abstraction or the electron transfer process, bromophenols cause an increase in radical species in which the unpaired... 

    A quantum chemical study on the OH radical quenching by natural antioxidant fisetin

    , Article Journal of Physical Organic Chemistry ; Volume 30, Issue 11 , 2017 ; 08943230 (ISSN) Bayat, A ; Fattahi, A ; Sharif University of Technology
    In this work, the antioxidant ability of fisetin was explored toward hydroxyl (•OH) radical in aqueous and lipid solution using density functional level of theory. Different reaction mechanisms have been studied: hydrogen atom transfer, single electron transfer followed by proton transfer, and radical adduct formation, and sequential proton loss electron transfer. Rate constants for all possible reaction sites have been calculated using conventional transition state theory in conjunction with the Collins-Kimball theory. Branching ratios for the different channels of reaction are reported for the first time. Results show that the reactivity of fisetin toward hydroxyl (•OH) radical takes place... 

    Persistent quantum coherence and strong coupling enable fast electron transfer across the cds/tio2 interface: a time-domain ab initio simulation

    , Article Journal of Physical Chemistry C ; Volume 122, Issue 44 , 2018 , Pages 25606-25616 ; 19327447 (ISSN) Mehdipour, H ; Akimov, A. V ; Jankowska, J ; Rezakhanai, A. T ; Tafreshi, S. S ; De Leeuw, N. H ; Moshfegh, A. Z ; Prezhdo, O. V ; Sharif University of Technology
    American Chemical Society  2018
    Fast transfer of photoinduced electrons and subsequent slow electron-hole recombination in semiconductor heterostructures give rise to long-lived charge separation which is highly desirable for photocatalysis and photovoltaic applications. As a type II heterostructure, CdS/TiO2 nanocomposites extend the absorption edge of the light spectrum to the visible range and demonstrate effective charge separation, resulting in more efficient conversion of solar energy to chemical energy. This improvement in performance is partly explained by the fact that CdS/TiO2 is a type II semiconductor heterostructure and CdS has a smaller energy band gap than UV-active TiO2. Ultrafast transient absorption... 

    First heterobimetallic AgI–CoIII coordination compound with both bridging and terminal –NO2 coordination modes: Synthesis, characterization, structural and computational studies of (PPh3)2AgI– (μ-κ2O,O′:κN-NO2)–COIII(DMGH)2(κN-NO2)

    , Article Acta Crystallographica Section C: Structural Chemistry ; Volume 74, Issue 8 , 2018 , Pages 882-888 ; 20532296 (ISSN) Kia, R ; Batmanghelich, S ; Raithby, P. R ; Sharif University of Technology
    Wiley-Blackwell  2018
    An unusual heterobimetallic bis(triphenylphosphane)(NO2)AgI–CoIII(dimethyl-glyoximate)(NO2) coordination compound with both bridging and terminal –NO2 (nitro) coordination modes has been isolated and characterized from the reaction of [CoCl(DMGH)2(PPh3)] (DMGH2 is dimethylglyoxime or N,N′-di-hydroxybutane-2,3-diimine) with excess AgNO2. In the title compound, namely bis(dimethylglyoximato-1κ2O,O′)(μ-nitro-1κN:2κ2O,O′)(nitro-1κN)bis(triphenyl-phosphane-2κP)cobalt(III)silver(I), [AgCo(C4H7N2O2)2(NO2)2(C18H15P)2], one of the ambidentate –NO2 ligands, in a bridging mode, chelates the AgI atom in an isobidentate κ2O,O′-manner and its N atom is coordinated to the CoIII atom. The other –NO2 ligand... 

    Investigation of the interfacial electron transfer kinetics in ferrocene-terminated oligophenyleneimine self-assembled monolayers

    , Article Langmuir ; Volume 36, Issue 42 , 2020 , Pages 12572-12579 Taherinia, D ; Sharif University of Technology
    American Chemical Society  2020
    In this article, the synthesis, characterization, and cyclic voltammetry (CV) measurements are reported for ferrocene-terminated oligophenyleneimine (OPI_Fc) and ferrocene-terminated conjugation-broken oligophenyleneimine (CB-OPI_Fc) self-assembled monolayers (SAMs) in two different electrolytes, namely, 1-ethyl-3-methylimidazolium-bis (trifluoromethyl-sulfonyl) imide (EMITFSI) ionic liquid and tetrabutylammonium hexafluorophosphate (Bu4NPF6) in acetonitrile (0.1 M solution). The SAMs were synthesized on Au surfaces by the sequential imine condensation reactions. CV was used to investigate the kinetics of electron transfer (ET) to the ferrocene, and it was observed that the standard ET rate... 

    First passage time distribution of chaperone driven polymer translocation through a nanopore: Homopolymer and heteropolymer cases

    , Article Journal of Chemical Physics ; Volume 135, Issue 24 , 2011 ; 00219606 (ISSN) Abdolvahab, R. H ; Metzler, R ; Ejtehadi, M. R ; Sharif University of Technology
    Combining the advection-diffusion equation approach with Monte Carlo simulations we study chaperone driven polymer translocation of a stiff polymer through a nanopore. We demonstrate that the probability density function of first passage times across the pore depends solely on the Péclet number, a dimensionless parameter comparing drift strength and diffusivity. Moreover it is shown that the characteristic exponent in the power-law dependence of the translocation time on the chain length, a function of the chaperone-polymer binding energy, the chaperone concentration, and the chain length, is also effectively determined by the Péclet number. We investigate the effect of the chaperone size on... 

    Amine functionalized TiO2 coated on carbon nanotube as a nanomaterial for direct electrochemistry of glucose oxidase and glucose biosensing

    , Article Journal of Molecular Catalysis B: Enzymatic ; Volume 68, Issue 2 , 2011 , Pages 206-210 ; 13811177 (ISSN) Tasviri, M ; Rafiee Pour, H. A ; Ghourchian, H ; Gholami, M. R ; Sharif University of Technology
    A nano-composite material consisting of amine functionalized TiO 2-coated carbon nanotubes was prepared and used for glucose oxidase (GOx) absorption. The GOx bearing nanomaterial was fixed on a glassy carbon electrode to construct a novel biosensor for glucose determination. The direct electrochemistry of immobilized GOx and its electron transfer parameters at the modified glassy carbon electrode were reported. The apparent heterogeneous electron transfer rate constant (ks) of GOx was estimated to be 3.5 s-1, which is higher than those reported previously. Amperometric detection of glucose resulted in a rapid (3 s) and stable response in the linear concentration range from 1.8 to 266 μM.... 

    Origin of the correlation of the rate constant of substrate hydroxylation by nonheme iron(IV)-oxo complexes with the bond-dissociation energy of the C-H bond of the substrate

    , Article Chemistry - A European Journal ; Volume 15, Issue 27 , 2009 , Pages 6651-6662 ; 09476539 (ISSN) Latifi, R ; Bagherzadeh, M ; De Visser, S ; Sharif University of Technology
    Wiley-VCH Verlag  2009
    Mononuclear nonheme iron containing systems are versatile and vital oxidants of substrate hydroxylation reactions in many biosystems, whereby the rate constant of hydroxylation correlates with the strength of the C-H bond that is broken in the process. The thermodynamic reason behind these correlations, however, has never been established. In this work results of a series of density functional theory calculations of substrate hydroxylation by a mononuclear nonheme iron(IV)-oxo oxidant with a 2 His/ 1Asp structural motif analogous to aketoglutarate dependent dioxygenases are presented. The calculations show that these oxidants are very efficient and able to hydroxylate strong C-H bonds,... 

    Bimodal electricity generation and aromatic compounds removal from purified terephthalic acid plant wastewater in a microbial fuel cell

    , Article Biotechnology Letters ; Volume 35, Issue 2 , 2013 , Pages 197-203 ; 01415492 (ISSN) Marashi, S. K. F ; Kariminia, H. R ; Savizi, I. S. P ; Sharif University of Technology
    Wastewater of purified terephthalic acid (PTA) from a petrochemical plant was examined in a membrane-less single chamber microbial fuel cell for the first time. Time course of voltage during the cell operation cycle had two steady phases, which refers to the fact that metabolism of microorganisms was shifted from highly to less biodegradable carbon sources. The produced power density was 31.8 mW m-2 (normalized per cathode area) and the calculated coulombic efficiency was 2.05 % for a COD removal of 74 % during 21 days. The total removal rate of different pollutants in the PTA wastewater was observed in the following order: (acetic acid) > (benzoic acid) > (phthalic acid) > (terephthalic... 

    Enhanced electron collection efficiency in dye-sensitized solar cells based on nanostructured TiO2 hollow fibers

    , Article Nano Letters ; Volume 10, Issue 5 , April , 2010 , Pages 1632-1638 ; 15306984 (ISSN) Ghadiri, E ; Taghavinia, N ; Zakeeruddin, S. M ; Grätzel, M ; Moser, J. E ; Sharif University of Technology
    Nanostructured TiO2 hollow fibers have been prepared using natural cellulose fibers as a template. This cheap and easily processed material was used to produce highly porous photoanodes incorporated in dye-sensitized solar cells and exhibited remarkably enhanced electron transport properties compared to mesoscopic films made of spherical nanoparticles. Photoinjected electron lifetime, in particular, was multiplied by 3-4 in the fiber morphology, while the electron transport rate within the fibrous photoanaode was doubled. A nearly quantitative absorbed photon-to-electrical current conversion yield exceeding 95% was achieved upon excitation at 550 nm and a photovoltaic power conversion...