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    An alternative mechanism for the formation of high density lipoprotein in peripheral tissue

    , Article Scientia Iranica ; Volume 23, Issue 2 , 2016 , Pages 600-608 ; 10263098 (ISSN) Damirchi, B ; Saidi, M. S ; Rismanian, M ; Firoozabadi, B ; Amininasab, M ; Sharif University of Technology
    Sharif University of Technology  2016
    High Density Lipoprotein (HDL) is a lipid-protein complex responsible for transporting cholesterol and triglyceride molecules, as these compounds are unable to dissolve in aqueous environments such as a bloodstream. Among the most well-known possible structures, the belt-like structure is the most common shape proposed for this vital bimolecular complex. In this structure, the protein scaffold encompasses the lipid bilayer and a planar circular structure is formed. Several HDL simulations with embedded components in the lipid section were performed. Here, we applied a series of molecular dynamic simulations using the MARTINI coarse grain force field to investigate an HDL model, with pores of... 

    Design, Manufacturing and Setting up the Injection and Mixing Teststand of Shear and Swirl injectors in Transcritical Condition

    , M.Sc. Thesis Sharif University of Technology Shokrzadeh Damirchi, Alireza (Author) ; Farshchi, Mohammad (Supervisor)
    The arena of supercritical combustion involves a set of unique physical phenomena that are different from what is observed in the spraying and combustion of a subcritical regime. Understand the complex physics of the flow field in transcritical and supercritical operating conditions and discovery of factors affecting them and the extent to which each of these factors affects the structure of the jet and consequently the quality of the mixing and combustion process, is one of the basic steps to optimize of cryogenic liquid fuel engine combustion chamber design. In this thesis, by studying the experimental researches of injection at sub-critical to super-critical conditions, it has been tried... 

    Modeling and stability analysis of truncated high density lipoprotein (HDL) system using MARTINI coarse grain technique

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 3 A , November , 2013 ; 9780791856215 (ISBN) Damirchi, B ; Rouhollahi, A ; Sohrabi, S ; Mehr, S. M. N ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2013
    Lipoproteins are biochemical compounds containing both proteins and lipids. These particles carry chemicals like cholesterol and triglycerides that are not soluble in aqueous solutions. This paper presents modeling of lipoprotein system using coarse grain molecular dynamics technique and stability analysis of this system in a water solution like blood. A high density lipoprotein (HDL) that consists of two annular monomers is modeled. Also there are lipid bilayers located in center of the rings, so the whole HDL and lipid bilayers are called lipoprotein system. First, all atom model is provided and then coarse-grain model is obtained using MARTINI technique. Modeling of the system in all atom... 

    Coarse Grain Molecular Dynamics Simulation of Drug Carrier Translocation into Cell Membrane

    , M.Sc. Thesis Sharif University of Technology Damirchi, Behzad (Author) ; Saidi, Mohammad Said (Supervisor) ; Firoozabadi, Bahar (Supervisor)
    With the increasing development of the pharmaceutical industry and producing drugs with specific performance, its transfer into cells is also very important. Cell membranes are effectively impermeable to hydrophilic compounds unless the permeation is facilitated by dedicated transport systems. This means that many hydrophilic compounds, including many promising drug candidates, fail to reach their intracellular target because they cannot spontaneously cross lipid membranes. As a consequence, there is much interest in finding ways to facilitate the transport of molecules across cell membranes. Cell-penetrating peptides (CPPs) in particular have shown much promise as potential delivery agents... 

    Microwave-induced Cannizzaro reaction over neutral γ-alumina as a polymeric catalyst [electronic resource]

    , Article Reactive and Functional Polymers ; 01/2002; 51(1):49-53 Pourjavadi, A. (Ali) ; Soleimanzadeh, B ; Marandi, G. B
    γ-Alumina is used to catalyze the Cannizzaro reaction in the absence of any base under microwave irradiation in high yields. In the case of terephthalaldehyde the reaction is carried out with high selectivity  

    SnCl4/SiO2: an efficient heterogeneous alternative for one-pot synthesis of β-acetamidoketones

    , Article Journal of the Chinese Chemical Society ; Volume 56, Issue 2 , 2009 , Pages 386-391 ; 00094536 (ISSN) Mirjalili, B. B. F ; Mahmoodi Hashemi, M ; Sadeghi, B ; Emtiazi, H ; Sharif University of Technology
    Enolizable ketones have been reacted in a one-pot method with aromatic aldehydes, acetyl chloride and acetonitrile at room temperature in the presence of SnCl4/SiO2 to furnish the corresponding β-acetamidoketones in improved yields. Acetylation of an aromatic hydroxyl group was observed while using 4-hydroxybenzaldehyde or vanillin and the corresponding β-acetamidoketones were isolated in an excellent yield  

    Turbulent flow in converging nozzles, part one: Boundary layer solution

    , Article Applied Mathematics and Mechanics (English Edition) ; Volume 32, Issue 5 , 2011 , Pages 645-662 ; 02534827 (ISSN) Maddahian, R ; Farhanieh, B ; Firoozabadi, B ; Sharif University of Technology
    The boundary layer integral method is used to investigate the development of the turbulent swirling flow at the entrance region of a conical nozzle. The governing equations in the spherical coordinate system are simplified with the boundary layer assumptions and integrated through the boundary layer. The resulting sets of differential equations are then solved by the fourth-order Adams predictor-corrector method. The free vortex and uniform velocity profiles are applied for the tangential and axial velocities at the inlet region, respectively. Due to the lack of experimental data for swirling flows in converging nozzles, the developed model is validated against the numerical simulations. The... 

    Numerical investigation of steady density currents flowing down an incline using v2̄ - F turbulence model

    , Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 129, Issue 9 , 2007 , Pages 1172-1178 ; 00982202 (ISSN) Khakzad, N ; Firoozabadi, B ; Farhanieh, B ; Sharif University of Technology
    The governing equations of two-dimensional steady density currents are solved numerically using a finite volume method. The v2̄-f turbulence model, based on standard k - s model, is used for the turbulence closure. In this method, all Reynolds stress equations are replaced with both a transport equation for v2̄ and an elliptic relaxation equation for f, a parameter closely related to the pressure strain redistribution term. The Simple-C procedure is used for pressure-velocity coupling. In addition, Boussinesq's approximation is used to obtain the momentum equation. The computed height of the progressive density current is compared to the measured data in the literature, resulting in good... 

    Numerical simulation of turbid-density current using v2̄ - f turbulence model

    , Article 2005 ASME International Mechanical Engineering Congress and Exposition, IMECE 2005, Orlando, FL, 5 November 2005 through 11 November 2005 ; Volume 261 FED , 2005 , Pages 619-627 ; 08888116 (ISSN); 0791842193 (ISBN); 9780791842195 (ISBN) Mehdizadeh, A ; Firoozabadi, B ; Farhanieh, B ; Sharif University of Technology
    The deposition behavior of fine sediment is an important phenomenon, and yet unclear to engineers concerned about reservoir sedimentation. An elliptic relaxation turbulence model (v2̄ - f model) has been used to simulate the motion of turbid density currents laden whit fine solid particles. During the last few years, the v2̄ - f turbulence model has become increasingly popular due to its ability to account for near-wall damping without use of damping functions. In addition, it has been proved that the v2̄ - f model to be superior to other RANS methods in many fluid flows where complex flow features are present. Due to low Reynolds number turbulence of turbidity current,(its critical Reynolds... 

    Analytical solution for creeping motion of a viscoelastic drop falling through a Newtonian fluid

    , Article Korea Australia Rheology Journal ; Vol. 26, issue. 1 , 2014 , pp. 91-104 ; ISSN: 1226119X Vamerzani, B. Z ; Norouzi, M ; Firoozabadi, B ; Sharif University of Technology
    In this paper, an analytical solution for steady creeping motion of viscoelastic drop falling through a viscous Newtonian fluid is presented. The Oldroyd-B model is used as the constitutive equation. The analytical solutions for both interior and exterior flows are obtained using the perturbation method. Deborah number and capillary numbers are considered as the perturbation parameters. The effect of viscoelastic properties on drop shape and motion are studied in detail. The previous empirical studies indicated that unlike the Newtonian creeping drop in which the drop shape is exactly spherical, a dimpled shape appears in viscoelastic drops. It is shown that the results of the present... 

    Theoretical and experimental study on the motion and shape of viscoelastic falling drops through Newtonian media

    , Article Rheologica Acta ; Volume 55, Issue 11-12 , 2016 , Pages 935-955 ; 00354511 (ISSN) Vamerzani, B. Z ; Norouzi, M ; Firoozabadi, B ; Sharif University of Technology
    Springer Verlag  2016
    In this paper, creeping motion of a viscoelastic drop falling through a Newtonian fluid is investigated experimentally and analytically. A polymeric solution of 0.08 % xanthan gum in 80:20 glycerol/water and silicon oil is implemented as the viscoelastic drop and the bulk viscous fluids, respectively. The shape and motion of falling drops are visualized using a high speed camera. The perturbation technique is employed for both interior and exterior flows, and Deborah and capillary numbers are considered as perturbation parameters up to second order. The product of Deborah and capillary numbers is also used as a perturbation parameter to apply the boundary condition on the deformation on the... 

    Minimizing uplink delay in delay-sensitive 5G CRAN platforms

    , Article 2nd IEEE 5G World Forum, 5GWF 2019, 30 September 2019 through 2 October 2019 ; 2019 , Pages 154-160 ; 9781728136271 (ISBN) Ataie, A ; Kanaanian, B ; Khalaj, B. H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    In this paper, we consider the problem of minimizing the uplink delays of users in a 5G cellular network. Such cellular network is based on a Cloud Radio Access Network (CRAN) architecture with limited fronthaul capacity, where our goal is to minimize delays of all users through an optimal resource allocation. Earlier works minimize average delay of each user assuming same transmit power for all users. Combining Pareto optimization and Markov Decision Process (MDP), we show that every desired balance in the trade-off among infinite-horizon average-reward delays, is achievable by minimizing a properly weighted sum delays. In addition, we solve the problem in two realistic scenarios;... 

    Microwave-induced Cannizzaro reaction over neutral γ-alumina as a polymeric catalyst

    , Article Reactive and Functional Polymers ; Volume 51, Issue 1 , 2002 , Pages 49-53 ; 13815148 (ISSN) Pourjavadi, A ; Soleimanzadeh, B ; Marandi, G. B ; Sharif University of Technology
    Microwave induced Cannizzaro reaction, which was performed in presence of neutral γ-alumina as a polymeric catalyst, was discussed. Cannizzaro reaction was carried out on alumina surface and other unknown products were also obtained. Solvent extraction method was utilized to isolate mild and selective benzyl alcohol and carboxylic acids  

    Feedback bit reduction for antenna selection methods in wireless systems

    , Article 2005 13th IEEE International Conference on Networks jointly held with the 2005 7th IEEE Malaysia International Conference on Communications, Kuala Lumpur, 16 November 2005 through 18 November 2005 ; Volume 1 , 2005 , Pages 229-233 ; 1424400007 (ISBN); 9781424400003 (ISBN) Shariatpanahi, P ; Babadi, B ; Hossein Khalaj, B ; Sharif University of Technology
    A well known method to reduce the intrinsic complexity of Multiple Input Multiple Output (MIMO) systems is to choose a subset of available antennas which have stronger links than the others, in order to perform the specified MIMO algorithm. The data resulted from the antenna selection process (at the receiver side) is sent back to the transmitter side via a feedback channel. There seems to be a need to reduce the number of feedack bits, specially when the number of antennas is not small. In this paper, we investigate the problem of reducing the number of feedback bits in antenna selection techniques. We've proposed two methods using vector quantization techniques to perform feedback bit... 

    A distributed locality-aware neighbor selection algorithm for P2P video streaming over wireless mesh networks

    , Article 2012 6th International Symposium on Telecommunications, IST 2012 ; 2012 , Pages 639-643 ; 9781467320733 (ISBN) Moayeri, F ; Akbari, B ; Khansari, M ; Ahmadifar, B ; Sharif University of Technology
    Nowadays, deployment of peer-to-peer video streaming systems over wireless mesh networks has attained raising popularity among large number of users around the world. In this paper, we present an efficient peer-to-peer live video streaming architecture over multi-hop wireless mesh networks. In our proposed architecture, we take the physical topology of network into account and based on a distributed distributed locality-aware neighbor selection algorithm in the overlay construction phase, we generate an efficient mesh-based overlay on top of wireless mesh networks. In locality-aware neighbor selection algorithm, instead of choosing randomly, peers find their best neighbors based on their... 

    Weighted sparse signal decomposition

    , Article ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings ; 2012 , Pages 3425-3428 ; 15206149 (ISSN) ; 9781467300469 (ISBN) Babaie Zadeh, M ; Mehrdad, B ; Giannakis, G. B ; Sharif University of Technology
    IEEE  2012
    Standard sparse decomposition (with applications in many different areas including compressive sampling) amounts to finding the minimum ℓ 0-norm solution of an underdetermined system of linear equations. In this decomposition, all atoms are treated 'uniformly' for being included or not in the decomposition. However, one may wish to weigh more or less certain atoms, or, assign higher costs to some other atoms to be included in the decomposition. This can happen for example when there is prior information available on each atom. This motivates generalizing the notion of minimal ℓ 0-norm solution to that of minimal weighted ℓ 0-norm solution. On the other hand, relaxing weighted ℓ 0-norm via... 

    Effect of miscible nitrogen injection on instability, particle size distribution, and fractal structure of asphaltene aggregates

    , Article Journal of Dispersion Science and Technology ; Volume 33, Issue 5 , 2012 , Pages 763-770 ; 01932691 (ISSN) Moradi, S ; Dabir, B ; Rashtchian, D ; Mahmoudi, B ; Sharif University of Technology
    Precipitation, aggregation, and breakup of asphaltene particles are studied under natural depletion and nitrogen injection processes by means of high pressure filtration and a photographic procedure coupled with image analysis. Filtration results show that nitrogen destabilizes asphaltenes extremely, and the problem is more severe for heavier crude samples. Bimodal histograms of particle size distribution show two agglomeration mechanisms: cluster aggregation dominant around bubble point pressure and diffusion limited far away. The fractal structure of aggregates is also altered by gas injection; it is observed that the flocculent masses grow in size and become more compact and organized... 

    Analytical investigation of boundary layer growth and swirl intensity decay rate in a pipe

    , Article Archive of Applied Mechanics ; Volume 81, Issue 4 , 2011 , Pages 489-501 ; 09391533 (ISSN) Maddahian, R ; Kebriaee, A ; Farhanieh, B ; Firoozabadi, B ; Sharif University of Technology
    In this research, the developing turbulent swirling flow in the entrance region of a pipe is investigated analytically by using the boundary layer integral method. The governing equations are integrated through the boundary layer and obtained differential equations are solved with forth-order Adams predictor-corrector method. The general tangential velocity is applied at the inlet region to consider both free and forced vortex velocity profiles. The comparison between present model and available experimental data demonstrates the capability of the model in predicting boundary layer parameters (e.g. boundary layer growth, shear rate and swirl intensity decay rate). Analytical results showed... 

    Capacity maximization in MIMO vehicular communication using a novel antenna selection algorithm

    , Article 2013 9th International Wireless Communications and Mobile Computing Conference, IWCMC 2013, Cagliari, Sardinia ; 2013 , Pages 1246-1251 ; 9781467324793 (ISBN) Mousavi, H. S ; Khalighinejad, B ; Khalaj, B. H ; Sharif University of Technology
    The capacity of multiple-input multiple-output (MIMO) systems in vehicular communication is investigated throughout this paper. The goal is to consider a link between a vehicle-side and a road-side unit in presence of line-of-sight in a way that the road-side end uses all available antennas but the vehicle-side end chooses a subset of available antennas such that the link capacity becomes maximized. In order to maximize the channel capacity a criterion is derived that forces some circumstances about the configuration of antenna array in vehicle-side. If such circumstances are satisfied the channel capacity will be at its maximum. By proposing an antenna selection algorithm, the conditions... 

    Novel method for cancer cell apoptosis by localized UV light with gold nanostructures: A theoretical investigation

    , Article Nano ; Volume 5, Issue 6 , 2010 , Pages 325-332 ; 17932920 (ISSN) Sasanpour, P ; Rashidian, B ; Rashidian, B ; Vossoughi, M ; Sharif University of Technology
    A novel approach for phototherapy is proposed. The proposed method is based on cell apoptosis according to halting activation of cancer cell membrane receptor by exposure to UV light pulses without any side effect. In the proposed method, gold nanoparticles are directed to cancerous cells by conjugating their surface with specific ligands. UV light is created locally adjacent to cells around the gold nanoparticles. UV light is generated due to nonlinear interaction of visible light with gold nanoparticles because of enhancement in third order nonlinear effects. For example, by using 780 nm laser, 260 nm UV will be generated around the nanoparticle because of third harmonic generation...