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    Smulation of Hydrogen Production by the Process of Thermal Decomposition of Methane

    , M.Sc. Thesis Sharif University of Technology Parishan, Samira (Author) ; Saboohi, Yadollah (Supervisor)
    Different disadvantages associated with using fossil fuels as the main energy source including crisis of wells’ depletion and serious environmental problems, causing by the emission of large quantities of greenhouse gases (GHG), especially carbon dioxide (CO2), has increased attention to replacing them with renewable and clean fuels such as wind, solar, and geothermal energy sources. Hydrogen, as a clean energy carrier, is one of the best fuels in terms of the environment and cost. So, it is recently receiving increasing attention and it may one day replace fossil fuels for various applications such as in automobiles and power stations. The main subject of this thesis was surveying the... 

    Investigation of the Influence of Geometry and External Field on Fluid Flow Through Carbon Nanotubes by Molecular Dynamics Simulation

    , M.Sc. Thesis Sharif University of Technology Khodabakhshi, Milad (Author) ; Moosavi, Ali (Supervisor)
    Water transportation through carbon nanotubes is key for designing nanodevices. The directed transport of water molecules through a rotating charged carbon nanotube (CNT) is investigated by molecular dynamics simulations. It is found that the net flux of continuous unidirectional water flow depended sensitively on the charge distribution, charge density and rotation of the CNT. we find that for a constant charge density, the water flux increases with the increase of the charge difference. Besides, we find that the water flux shows a nonlinear dependence on the angular velocity of the rotation. The rotation of the CNT with low angular velocities, can not generate a continuous water flux. The... 

    Synthesis and Properties of Cationic Polynulcear Complexes of Manganese with the Anionic Keggin Type Polyoxometalates as Single Molecule Magnets Hx[Mn4O2(CH3COO)7(bipy)2]n[Kegiin-Polyoxometalates]m.yH2O

    , M.Sc. Thesis Sharif University of Technology Daneshmand Kashani, Pargol (Author) ; Mohammdi Boghaei, Davar (Supervisor)
    Single molecule magnets due to their magnetic tunneling effect and the interaction they have with an external magnetic field are used widely in quantum computing and also the storage of data with high capacities. Polyoxometalates that are used as counter ions for cationic single molecule magnets, are able to affect their spin-couple nature via a magnetic exchange and also have an influence on the crystal accumulation in order to change the magnetic property of the molecule. In this research the probability of sedimenting a cationic single molecule magnet, [Mn4O2(CH3COO)7(bipy)2]+, with the use of anionic polyoxometalates with Keggin structures has been investigated. Thus, the single... 

    Theoretical Investigation of Hydrogen Bonding Effects on Interaction of Metal Nanoclusters with Histidine, Oxidation of Olefins by MnO4– & Acidity Enhancement of Alcohols

    , Ph.D. Dissertation Sharif University of Technology Jebeli Javan, Marjan (Author) ; Fattahi, Alireza (Supervisor) ; Mahmoodi Hashemi, Mohammad (Supervisor) ; Jamshidi, Zahra (Supervisor)
    This thesis is divided into three parts: In part I, interactions of neutral and anionic forms of histidine with coinage metal nano clusters M3 (M = Au, Ag and Cu) are investigated. Results demonstrate that nonconventional M…H-O hydrogen bonds and M-X bonds (X = N, O) play stabilization roles in interactions of histidine and metal nano clusters. Presence of negative charge in ligand leads to increase of binding energy of complexes. In the next step, the effects of coinage metal nano clusters on the gas-phase acidity of weak organic acid (histidine) have been explored. The acidity of isolated histidine is compared with the acidity of its Au3–, Ag3– and Cu3–complexed species. Moreover, pKa... 

    Survying the Process of Photodissociation of Methane with Using the Femto Second Lasers

    , M.Sc. Thesis Sharif University of Technology Irani, Elnaz (Author) ; Sadighi Bonabi, Rasoul (Supervisor)
    In this project , the dissociation of methane in the presence of Ti:Sapphire laser with parameters of 1014wcm-2, 800nm wave lengths and 100fs pulse width have been investigated theoretically, by using the Gaussian03 package –computational chemistry program that is capable of predicting many properties of atomic and molecular systems. It is based upon the fundamental laws of quantum mechanism. By considering some limitations in approximate techniques and incapability of advancing them, numerical calculation of solving the time dependent Schrödinger equation in order to improve the results and find more quantum dynamic information is applied. Therefore at first, by Gaussian03 package some of... 

    Separation of Hydrogen Molecule from Methane Molecule by Intense Femtosecond Laser Pulses

    , M.Sc. Thesis Sharif University of Technology Moeini Alishah, Hamed (Author) ; Sadighi Bonabi, Rasoul (Supervisor)
    Conversion of Methane molecule to valuable heavier hydrocarbon and hydrogen by using of short pulse lasers is investigated. The dynamical information of molecule such as orientation, dipole moment variations with binding length, and potential energy levels are initially produced by using Gaussian software. Based on this information the Schrödinger wave equation for this polyatomic molecule is numerically solved. Then by selecting the various laser parameters and installing of them in the Hamiltonian of the mentioned system, the dependence of hydrogen transition and separation probability on these parameters are investigated. In this work by radiating of the laser beam along the C2 symmetry... 

    Study of Surface Growth of Organic Thin Film

    , M.Sc. Thesis Sharif University of Technology Hosseini, Hadi (Author) ; Rahimi Tabar, Mohammad Reza (Supervisor)
    In recent decades the Due to development of coating techniques and the diversity of high organic matter, Discussion of organic coating materials being raised. Moreover, because of many applications of organic thin film in electronic and optical systems for example OTFTs and OLEDs Organic thin film growth topic is very interesting for scientists. Among these, some scientists study the theory and another bunch of scientists pay to practical aspects of this topic. In this thesis I pay to the theoretical level of Organic thin film growth and I simulate the system includes a collection of molecules, Went on to study some statistical properties of the system will be discussed and the dynamic... 

    Emergence of molecular chirality by vibrational Raman scattering

    , Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 88, Issue 3 , 2013 ; 10502947 (ISSN) Taher Ghahramani, F ; Shafiee, A ; Sharif University of Technology
    In this study, we apply the monitoring master equation describing decoherence of internal states to an optically active molecule prepared in a coherent superposition of nondegenerate internal states interacting with thermal photons at low temperatures. We use vibrational Raman scattering theory up to the first chiral-sensitive contribution, i.e., the mixed electric-magnetic interaction, to obtain scattering amplitudes in terms of molecular polarizability tensors. The resulting density matrix is used to obtain elastic decoherence rates  

    Edge-functionalization of graphene by polyglycerol; A way to change its flat topology

    , Article Polymer (United Kingdom) ; Volume 54, Issue 12 , 2013 , Pages 2917-2925 ; 00323861 (ISSN) Movahedi, S ; Adeli, M ; Fard, A. K ; Maleki, M ; Sadeghizadeh, M ; Bani, F ; Sharif University of Technology
    This work presents a procedure for functionalization of graphene sheets from edges by polyglycerol. Hyperbranched polyglycerol with a bi-dentate aromatic segment in its focal point was synthesized and used to sandwich graphene sheets from the cut-edges. Due to the hydrophobicity of the flat surface of the edge-functionalized graphenes and hydrophilicity of their edges, they changed their conformation from the extended- to the closed-state and formed nanocapsules in aqueous solutions. Spectroscopy and microscopy evaluations showed that the average size for nanocapsules is 300 nm. They were able to encapsulate hydrophobic molecules such as doxorubicin in aqueous solutions with a high loading... 

    Simulation of optical interstellar scintillation

    , Article Astronomy and Astrophysics ; Volume 552, Article No. A93 , 2013 ; 00046361 (ISSN) Habibi, F ; Moniez, M ; Ansari, R ; Rahvar, S ; Sharif University of Technology
    Aims. Stars twinkle because their light propagates through the atmosphere. The same phenomenon is expected on a longer time scale when the light of remote stars crosses an interstellar turbulent molecular cloud, but it has never been observed at optical wavelengths. The aim of the study described in this paper is to fully simulate the scintillation process, starting from the molecular cloud description as a fractal object, ending with the simulations of fluctuating stellar light curves. Methods. Fast Fourier transforms are first used to simulate fractal clouds. Then, the illumination pattern resulting from the crossing of background star light through these refractive clouds is calculated... 

    The effect of small scale on the pull-in instability of nano-switches using DQM

    , Article International Journal of Solids and Structures ; Volume 50, Issue 9 , 2013 , Pages 1193-1202 ; 00207683 (ISSN) Mousavi, T ; Bornassi, S ; Haddadpour, H ; Sharif University of Technology
    This paper deals with the study of the small scale effect on the pull-in instability of nano-switches subjected to electrostatic and intermolecular forces. Using Eringen's nonlocal elasticity theory, the nonlocal Euler-Bernoulli beam model is derived through virtual displacement principle. The static governing equation which is extremely nonlinear due to the intermolecular and electrostatic attraction forces is solved numerically by differential quadrature method. The accuracy of the present method is verified by comparing the obtained results with the finite difference method and those in the literatures and very good agreement is obtained. Finally a comprehensive study is carried out to... 

    Enhanced autoionization of water at phospholipid interfaces

    , Article Journal of Physical Chemistry C ; Volume 117, Issue 1 , 2013 , Pages 510-514 ; 19327447 (ISSN) Mashaghi, A ; Partovi Azar, P ; Jadidi, T ; Anvari, M ; Jand, S. P ; Nafari, N ; Tabar, M. R. R ; Maass, P ; Bakker, H. J ; Bonn, M ; Sharif University of Technology
    The structure and autoionization of water at the water-phospholipid interface are investigated by ab initio molecular dynamics and ab initio Monte Carlo simulations using local density approximation (LDA) and generalized gradient approximation (GGA) for the exchange-correlation energy functional. Depending on the lipid headgroup, strongly enhanced ionization is observed, leading to the dissociation of several water molecules into H+ and OH- per lipid. The results can shed light on the phenomena of the high proton conductivity along membranes that has been reported experimentally  

    Nanocar and nanotruck motion on gold surface

    , Article 1st International Conference on Manipulation, Automation and Robotics at Small Scales, MARSS 2016, 18 July 2016 through 21 July 2016 ; 2016 ; 9781509015108 (ISBN) Nemati, A. R ; Nejat Pishkenari, H ; Meghdari, A ; Shorabpour, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    In this paper we have studied the motion of a nanocar and nanotruck on gold substrate using the classical molecular dynamics method. Analyzing the motion regime of the nanocar at different temperatures is one of the main goals of this paper. In the past years, similar molecules such as Trimmer, Z-car and nanotruck have been simulated by Konyukhov and Akimov. To increase the modeling accuracy in this paper we have used classical molecular dynamics contrary to previous works which used a rigid body molecular dynamics method. The result of our simulations were compared qualitatively to the experimental tests performed by Zhang et al. [12]. There was a good agreement between the results achieved... 

    Effect of asphaltene and resin on interfacial tension of acidic crude oil/ sulfate aqueous solution: Experimental study

    , Article Fluid Phase Equilibria ; Volume 414 , 2016 , Pages 149-155 ; 03783812 (ISSN) Lashkarbolooki, M ; Ayatollahi, S ; Sharif University of Technology
    Elsevier  2016
    Although the capability of using sulfate anion as a wettability modiffier is well established, no systematic investigation on the effect of sulfate ions and natural surfactants in the crude oil including asphaltene and resin on the interfacial tension (IFT) of acidic crude oil (ACO)/sulfate were performed. In this regards, the fluid/fluid interactions are tested through the IFT measurements for ACO, asphaltene and resin extracted from ACO in the presence of sulfate salts including Na2SO4, MgSO4 and CaSO4 while the concentration of each salt ranges between 0 and 45000 ppm. The obtained results demonstrate that the capability of asphaltene molecules is higher for IFT reduction compared with... 

    Kinetic modeling of thermal hydrocracking of a paraffinic feedstock

    , Article Energy and Fuels ; Volume 30, Issue 4 , 2016 , Pages 3374-3384 ; 08870624 (ISSN) Hajian, H ; Khorasheh, F ; Sharif University of Technology
    American Chemical Society  2016
    A kinetic model based on a mechanistic approach was developed for thermal hydrocracking of a paraffinic feedstock. The hydrocarbon feed was described as a mixture of representative molecules based on structural group analysis (SGA) where information from elemental analysis, H1, and C13-NMR of the feed were used to obtain the average concentration of various structural groups from which representative molecules were constructed. The behavior of the feedstock under reaction conditions was described in terms of the reaction of the individual molecules. The reaction of each of the representative molecules and the corresponding product distribution was based on free radical mechanisms. The... 

    Possibility of methane conversion into heavier hydrocarbons using nanosecond lasers

    , Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 156 , 2016 , Pages 118-122 ; 13861425 (ISSN) Navid, H. A ; Irani, E ; Sadighi Bonabi, R ; Sharif University of Technology
    Elsevier  2016
    Effect of nanosecond lasers on the methane dissociation is experimentally studied by using three different laser wavelengths at 248 nm, 355 nm and 532 nm. C2H2 generation is measured as a major reaction product in experiments and the energy consumptions in production of this component are measured as 5.8 MJ/mol, 3.1 MJ/mol and 69.0 MJ/mol, for 355 nm, 532 nm and 248 nm wavelengths, respectively. The mechanism of conversion and production of new stable hydrocarbons is also theoretically investigated. It is found that in theoretical calculations, the ion-molecule reactions should be included and this leads to a unique approach in proper explanation of the experimental measurements  

    The ITO-capped WO3 nanowires biosensor based on field-effect transistor in label-free protein sensing

    , Article Applied Physics A: Materials Science and Processing ; Volume 123, Issue 5 , 2017 ; 09478396 (ISSN) Shariati, M ; Sharif University of Technology
    Springer Verlag  2017
    The fabrication of ITO-capped WO3 nanowires associated with their bio-sensing properties in field-effect transistor diagnostics basis as a biosensor has been reported. The bio-sensing property for manipulated nanowires elucidated that the grown nanostructures were very sensitive to protein. The ITO-capped WO3 nanowires biosensor showed an intensive bio-sensing activity against reliable protein. Polylysine strongly charged bio-molecule was applied as model system to demonstrate the implementation of materialized biosensor. The employed sensing mechanism was ‘label-free’ and depended on bio-molecule’s intrinsic charge. For nanowires synthesis, the vapor–liquid–solid mechanism was used.... 

    A new approach to flexible humidity sensors using graphene quantum dots

    , Article Journal of Materials Chemistry C ; Volume 5, Issue 35 , 2017 , Pages 8966-8973 ; 20507534 (ISSN) Hosseini, Z. S ; Iraji Zad, A ; Ghiass, M. A ; Fardindoost, S ; Hatamie, S ; Sharif University of Technology
    Highly sensitive flexible humidity sensors based on graphene quantum dots (GQDs) were developed. The GQDs were prepared using a facile hydrothermal method and characterized considering morphological, structural, and compositional experiments. Then, their humidity sensing properties in correlation with flexibility characteristics were investigated. Good selectivity and response (∼390 for a RH change of 99%), broad detection range (1-100% RH), rather short response and recovery times (12 and 43 s, respectively) as well as flexibility were obtained, demonstrating that the GQD sensors have potential for application in wearable electronics and RH monitoring. Detection of hydrogen (H2) gas by the... 

    An adaptive pulse-width modulation for limited molecule production and storage

    , Article 2018 Iran Workshop on Communication and Information Theory, IWCIT 2018, 25 April 2018 through 26 April 2018 ; 2018 , Pages 1-6 ; 9781538641491 (ISBN) Khaloopour, L ; Mirmohseni, M ; Nasiri Kenari, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    The nature of molecular transmitter imposes some limitations on the molecule production process and its storage. As these molecules act the role of the information carriers, their limitation affect the transmission process and the system performance considerably. In this paper, we focus on these limitations at the transmitter, the limited production rate and finite storage capacity. We consider a time-slotted communication where the transmitter opens its outlet and releases the stored molecules for a time duration to send bit '1' and remains silent to send bit '0'. By changing the duration molecules are released, we propose an adaptive pulse-width modulation. The objective is to find the... 

    Adaptive release duration modulation for limited molecule production and storage

    , Article IEEE Transactions on Molecular, Biological, and Multi-Scale Communications ; Volume 5, Issue 2 , 2019 , Pages 139-152 ; 23327804 (ISSN) Khaloopour, L ; Mirmohseni, M ; Nasiri Kenari, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    The nature of molecular transmitter imposes some limitations on the molecule production process and its storage. As the molecules act the role of the information carriers, the limitations affect the transmission process and the system performance considerably. In this paper, we focus on the transmitter's limitations, in particular, the limited molecule production rate and the finite storage capacity. We consider a time-slotted communication where the transmitter opens its outlets and releases the stored molecules for a specific time duration to send bit '1' and remains silent to send bit '0'. By changing the Release Duration (RD), we propose an adaptive RD modulation. The objective is to...