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    Conversion of 3,6-O-dimethylfluorescein to fluorescein-based xanthylium derivative: characterization and covalent attachment to bovine serum albumin

    , Article ChemistrySelect ; Volume 4, Issue 36 , 2019 , Pages 10681-10687 ; 23656549 (ISSN) Kalhor, H. R ; Rezaei, M ; Sharif University of Technology
    Wiley-Blackwell  2019
    Xanthene dyes, such as fluorescein and rhodamine, have played crucial rules in biological sciences especially covalent attachment of these organic compounds to biomolecules. 3-O-methylfluorescein and 3,6-O-dimethylfluorescein were synthesized and purified using a facile procedure. 3,6-O-dimethylfluorescein, which lacks fluorescence, was treated with sodium hydroxide and sulfuric acid solutions, giving rise to yellow and green fluorescent compounds, respectively. In both basic and acidic conditions, donor-acceptor structures were formed. The reaction of 3,6-O-dimethylfluorescein with acids, in a reversible manner, emitted green fluorescence, whereas its reaction with hydroxide ion,... 

    Modeling the effect of mould wall roughness on the melt flow simulation in casting process

    , Article Applied Mathematical Modelling ; Volume 28, Issue 11 , 2004 , Pages 933-956 ; 0307904X (ISSN) Mirbagheri, S. M. H ; Dadashzadeh, M ; Serajzadeh, S ; Taheri, A. K ; Davami, P ; Sharif University of Technology
    In this investigation a computational model has been developed which includes heat and mass transfer as well as effects of backpressure, and mould wall friction for the simulation of incompressible flow with free surfaces in mould cavity filling. The simulation of flow with free surfaces is based on the SOLA-VOF numerical algorithm, utilizing the finite difference method. The solid and free boundary conditions have been modified and a new algorithm has been developed to calculate the effect of cavity pressure and wall-slip ratio, during mould filling. In this algorithm, the effect of wall-slip ratio on filling pattern has been modeled with an experimental function. In order to verify the... 

    Simulation of melt flow in coated mould cavity in the casting process

    , Article Journal of Materials Processing Technology ; Volume 142, Issue 2 , 2003 , Pages 493-507 ; 09240136 (ISSN) Mirbagheri, S. M. H ; Esmaeileian, H ; Serajzadeh, S ; Varahram, N ; Davami, P ; Sharif University of Technology
    In this investigation, simulation of the 3D flow of incompressible molten metal in a mould cavity has been carried out. A code has been developed to include heat transfer and permeability of coating utilizing the finite difference method (FDM). To achieve this, solid and free boundary conditions have been modified and a new algorithm has been proposed to calculate the effect of coating permeability during mould filling. In this algorithm, the effect of coating permeability on the filling pattern has been modelled and compared with an experiment. The modelling of molten metal flow and the location of free surfaces has been simulated based on the SOLution Algorithm-Volume Of Fraction... 

    3D computer simulation of melt flow and heat transfer in the lost foam casting process

    , Article International Journal for Numerical Methods in Engineering ; Volume 58, Issue 5 , 2003 , Pages 723-748 ; 00295981 (ISSN) Mirbagheri, S. M. H ; Varahram, N ; Davami, P ; Sharif University of Technology
    A new mathematical model has been developed to simulate mould filling in the lost foam casting process, using the finite difference method. The simulation of molten flow and track of free surfaces is based on the SOLA-VOF numerical technique. An algorithm was developed to calculate the gas pressure of the evaporated foam during the mould filling. The effect of backpressure on the filling behaviour was modelled with an experimental function by adding three-dimensions 3DVOF functions. In order to verify the computational results, a thin grey iron plate was poured into a transparent mould. Cavity filling, foam depolymerization and gap formation were recorded with a 16mm high-speed camera. A... 

    Simulation of mould filling in lost foam casting process

    , Article International Journal of Cast Metals Research ; Volume 16, Issue 6 , 2003 , Pages 554-565 ; 13640461 (ISSN) Mirbagheri, S. M. H ; Ashuri, H ; Varahram, N ; Davami, P ; Sharif University of Technology
    Maney Publishing  2003
    In this investigation, an algorithm was developed to calculate the gas pressure at the melt/foam interface (gap) owing to degraded foam during mould filling in the lost foam casting process (LFC). The effect of back-pressure on mould filling was modelled using a new experimental function by the addition of a three-dimensional volume of fluid (3D-VOF) function. The molten flow and free surface were simulated using the solution algorithm-VOF (SOLA-VOF) numerical technique. To simulate the three-dimensional incompressible flow in the LFC, the pressure boundary conditions, heat transfer and foam gas pressure effect were modified. Finally, in order to verify the computational results of... 

    Investigation and Study of Microstructure, Dielectric and Non-ohmic Properties of tin and Cobalt Oxide Systems Co-Doped with Electron Donor and Acceptor Elements

    , M.Sc. Thesis Sharif University of Technology Behdarvandan, Nazanin (Author) ; Nemati, Ali (Supervisor) ; Maleki Shahraki, Mohammad (Supervisor)
    In recent years, there are continuous researches on replacing new dielectrics with suitable dielectric properties (including high dielectric coefficient, low loss factor, high breakdown voltage, and high nonlinear coefficient simultaneously). One of these new materials is co-doped titanium oxide with donor and acceptor of electron, which in spite of having high dielectric coefficient and low loss factor. it has low breakdown voltage and researches on improving the disadvantages of this dielectric are ongoing. Due to the structural similarities between tin oxide and titanium oxide, the tin oxide can be an interesting system for studying and improving disadvantages in this field. In this study... 

    Towards developing efficient metalloporphyrin-based hybrid photocatalysts for CO2reduction; an: ab initio study

    , Article Physical Chemistry Chemical Physics ; Volume 22, Issue 40 , 2020 , Pages 23128-23140 Ostovan, A ; Papior, N ; Zahedi, M ; Moshfegh, A. Z ; Sharif University of Technology
    Royal Society of Chemistry  2020
    A series of thiophene-based donor-acceptor-donor (D-A-D) oligomer substituted metalloporphyrins (MPors) with different 3d central metal-ions (M = Co, Ni, Cu, and Zn) were systematically investigated to screen efficient hybrid photocatalysts for CO2 reduction based on density functional theory (DFT) and time-dependent DFT simulations. Compared with base MPors, the newly designed hybrid photocatalysts have a lower bandgap energy, stronger and broader absorption spectra, and enhanced intermolecular charge transfer, exciton lifetime, and light-harvesting efficiency. Then, the introduction of D-A-D electron donor (ED) groups into the meso-positions of MPors is a promising method for the... 

    Influence of the hydrogen bonding on the basicity of selected macrocyclic amines

    , Article Journal of Physical Organic Chemistry ; Volume 25, Issue 9 , 2012 , Pages 803-810 ; 08943230 (ISSN) Nasiri, M ; Shakourian Fard, M ; Fattahi, A ; Sharif University of Technology
    The optimized minimum-energy geometries of different macrocyclic amines and their protonated structures were determined by using ab initio and density functional theory (DFT) calculations. All the gas phase optimizations and energy calculations were performed at the DFT/B3LYP/6-311++G(d,p) level of theory. The HF/6-31 + G(d,p) level was used for all single point calculations in the solution phase. Geometry optimizations indicate that the most stable structures are stabilized by intramolecular hydrogen bonds. The proton affinity (PA) of macrocyclic amines is controlled by the strength of intramolecular hydrogen bonds of macrocyclic amines. These hydrogen bonds strongly influence the basicity... 

    Molecular dynamics simulation and MM-PBSA calculations of sickle cell hemoglobin in dimer form with Val, Trp, or Phe at the lateral contact

    , Article Journal of Physical Organic Chemistry ; Volume 23, Issue 9 , March , 2010 , Pages 866-877 ; 08943230 (ISSN) Abroshan, H ; Akbarzadeh, H ; Parsafar, G. A ; Sharif University of Technology
    As the delay time and hence nuclei formation play a crucial role in the pathophysiology of sickle cell disease, MD simulation and molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) calculations have been performed on three systems of hemoglobin; namely dimer of hemoglobin with valine (Hb S), tryptophan (Hbβ6W), and phenylalanine (Hbβ6F) at β6 position. The structural changes due to these aromatic substitutions are investigated. It is shown that β subunits have significant impact on the differences between a dimer and other crystal structures. Transition from a dimer to polymer for Hb S system affects the donor molecule more than that of the acceptor. In the case of donor and... 

    Measurement and calculation of 13C and 15N NMR chemical-shift tensors of a push-pull ethylene

    , Article Canadian Journal of Chemistry ; Volume 87, Issue 4 , 2009 , Pages 563-570 ; 00084042 (ISSN) Amini, S. K ; Tafazzoli, M ; Jenkins, H. A ; Goward, G. R ; Bain, A. D ; Sharif University of Technology
    Methyl 3-dimethylamino-2-cyanocrotonate (MDACC) has a remarkably weak carbon-carbon double bond. It has strong electron-withdrawing groups on one end and electron-donating groups on the other: a so-called push-pull ethylene. To investigate this unusual electronic structure, we have determined the crystal structure and measured both the 13C and 15N NMR chemical-shift tensors. These measurements are supplemented by shielding-tensor calculations done with density functional methods. The large difference (approximately 100 ppm) between isotropic chemical shifts of the two alkenyl carbons reflects a large charge release from the electron-donating side of C=C double bond to the... 

    Persian Liquorice extract as a highly efficient sustainable corrosion inhibitor for mild steel in sodium chloride solution

    , Article Journal of Cleaner Production ; Volume 210 , 2019 , Pages 660-672 ; 09596526 (ISSN) Alibakhshi, E ; Ramezanzadeh, M ; Haddadi, S. A ; Bahlakeh, G ; Ramezanzadeh, B ; Mahdavian, M ; Sharif University of Technology
    Elsevier Ltd  2019
    The Persian Liquorice was introduced as a sustainable corrosion inhibitor with excellent inhibition action for mild steel in sodium chloride solution. Persian Liquorice is a root of Glycyrrhiza glabra including many active compounds like Glycyrrhizin (GL), 18β- Glycyrrhetinic acid (GA), Liquritigenin (LTG), Licochalcone A (LCA), Licochalcone E (LCE), and Glabridin (GLD). The Fourier transform infrared (FT-IR) spectroscopy was utilized to track various active components exist in the Persian Liquorice extract. Electrochemical impedance spectroscopy, potentiodynamic polarization and electrochemical current noise measurements were conducted to investigate the corrosion inhibition role of various... 

    Optimization of some experimental parameters in the electro membrane extraction of chlorophenols from seawater

    , Article Journal of Chromatography A ; Volume 1216, Issue 45 , 2009 , Pages 7687-7693 ; 00219673 (ISSN) Lee, J ; Khalilian, F ; Bagheri, H ; Lee, H. K ; Sharif University of Technology
    An electro membrane extraction (EME) methodology was utilized to study the isolation of some environmentally important pollutants, such as chlorophenols, from aquatic media based upon the electrokinetic migration process. The analytes were transported by application of an electrical potential difference over a supported liquid membrane (SLM). A driving force of 10 V was applied to extract the analytes through 1-octanol, used as the SLM, into a strongly alkaline solution. The alkaline acceptor solution was subsequently analyzed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. The parameters influencing electromigration, including volumes and pH of the donor and...