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    Investigation the Effect of Process Parameters on the Synthesis of Nanometric Yttrium Aluminum Garnet Powder via Sol-Gel Combustion Method

    , M.Sc. Thesis Sharif University of Technology Zareh, Arezoo (Author) ; Maddah Hosseini, Hamid Reza (Supervisor) ; Nemati, Ziarat Ali (Supervisor)
    Yttrium Aluminum Garnet powders possessing controlled size distribution has found applications in production of transparent ceramics, phosphors, laser host materials and composites. Sol-Gel Combustion process is one of the versatile methods to produce nanometeric garnet powders. This procedure is based on combustion of a concentrated gel of metal salts and fuel in an exothermic reaction which leads to nanoparticles formation. pH value of solution and employed fuel system strongly affect production quality and single phase nanopowder can be synthesized by well monitoring these parameters. In this study nanocrystalline Yttrium Aluminum Garnet powders was Synthesized via sol-gel combustion... 

    Mesoporous silica nanoparticles (MCM-41) coated PEGylated chitosan as a pH-Responsive nanocarrier for triggered release of erythromycin [electronic resource]

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; 2014, Volume 63, Issue 13, Pages 692-697 Pourjavadi, A. (Ali) ; Mazaheri Tehrani, Zahra ; Sharif University of Technology
    A pH-responsive drug delivery system based on core shell structure of mesoporous silica nanoparticle (MSN) and chitosan-PEG copolymer was prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and high-resolution transmission microscope (HR-TEM) techniques. In order to improve compatibility MSN and drug, mesoporous nanosilica was modified by 3-aminopropyl triethoxysilane. The release of erythromycin (a macrolide antibiotic) as a model drug was investigated in two pHs, 7.4 and 5.5  

    Modified carrageenan. 4. Synthesis and swelling behavior of crosslinked kappa C-g-AMPS superabsorbent hydrogel with antisalt and pH-responsiveness properties [electronic resource]

    , Article Journal of Applied Polymer Science ; Vol.98, No.1, 255-263, 2005 Pourjavadi, A. (Ali) ; Hosseinzadeh, H ; Mazidi, R
    To synthesize a novel biopolymer-based superabsorbent hydrogel, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) was grafted onto kappa-carrageenan (KC) backbones. The graft copolymerization reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator, N,N,N',N'-tetramethyl ethylenediamine (TMEDA) as an accelerator, and N,N'-methylene bisacrylamide (MBA) as a crosslinker. A proposed mechanism for KC-g-AMPS formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The affecting variables on swelling capacity, i.e., the initiator, the crosslinker, and the monomer concentration, as well as reaction temperature,... 

    An analysis of cosmic neutrinos: flavor composition at source and neutrino mixing parameters

    , Article Nuclear Physics B ; Volume 821, Issue 1-2 , 2009 , Pages 197-214 ; 05503213 (ISSN) Esmaili, A ; Farzan, Y ; Sharif University of Technology
    We examine the feasibility of deriving neutrino mixing parameters δ and θ13 from the cosmic neutrino flavor composition under the assumption that the flavor ratios of the cosmic neutrinos at the source were Fνe + Fover(ν, ̄)e : Fνμ + Fover(ν, ̄)μ : Fντ + Fover(ν, ̄)τ = 1 : 2 : 0. We analyze various uncertainties that enter the derivation of δ and θ13 from the ratio of the shower-like to μ-tracks events which is the only realistic source of information on the flavor composition at neutrino telescopes such as ICECUBE. We then examine to what extent the deviation of the initial flavor ratio from 1 : 2 : 0 can be tested by measurement of this ratio at neutrino telescopes taking into account... 

    Semileptonic decay of a polarized top quark in the noncommutative standard model

    , Article Physical Review D - Particles, Fields, Gravitation and Cosmology ; Volume 74, Issue 2 , 2006 ; 15507998 (ISSN) Mohammadi Najafabadi, M ; Sharif University of Technology
    In this paper we study the noncommutative effects to the lepton spectrum from the decay of a polarized top quark. It is shown that the lowest contribution comes from the quadratic terms of the noncommutative parameter. The deviations from the standard model are significant for small values of the noncommutative characteristic scale. However, the charged lepton spin correlation coefficient has a remarkable deviation from the standard model from very low values of the noncommutative characteristic scale to 1 TeV. © 2006 The American Physical Society  

    Approximation of titration curves by artificial neural networks and its application to pH control

    , Article Scientia Iranica ; Volume 6, Issue 5 , 2000 , Pages 82-91 ; 10263098 (ISSN) Pishvaie, M. R ; Shahrokhi, M ; Sharif University of Technology
    Sharif University of Technology  2000
    Advanced model-based control of pH processes is noticeably a chemical modeling issue, because it can have a profound effect on the attainable control quality. This is especially the case when the pH regulation of streams, consisting of hundreds of constituents with varying concentrations, is encountered. The severe non-linear behavior of pH processes is reflected in the titration curve of the process stream. The performances of all model-based controllers are highly dependent on the accuracy of the model. Considering a great number of parameters such as dissociation constants, solubility products and characteristic concentrations places the designer in a dilemma of choosing between... 

    Partially hydrolyzed kappa carrageenan - polyacrylonitrile as a novel biopolymer-based superabsorbent hydrogel: synthesis, characterization, and swelling behaviors

    , Article Polymer Engineering and Science ; Volume 46, Issue 12 , 2006 , Pages 1778-1786 ; 00323888 (ISSN) Savoji, M. T ; Pourjavadi, A ; Sharif University of Technology
    In this paper, synthesis and swelling behavior of a novel superabsorbent hydrogel based on kappa carrageenan (κC) and polyacrylonitrile (PAN) was investigated. To achieve partially hydrolyzed κC-PAN hydrogel, physical mixture of κC and PAN was hydrolyzed by NaOH solution. During alkaline hydrolysis, the nitrile groups of PAN are converted to a mixture of hydrophilic carboxamide and carboxylate groups follow by in situ crosslinking of the grafted PAN chains. The reaction variables affecting on the swelling capacity of the hydrogel were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. Under the optimized conditions concluded, super swelling hydrogel... 

    Smartphone-based portable device for rapid and sensitive pH detection by fluorescent carbon dots

    , Article Sensors and Actuators A: Physical ; Volume 332 , 2021 ; 09244247 (ISSN) Ehtesabi, H ; Asadollahi, A ; Hallaji, Z ; Goudarzi, M ; Rezaei, A ; Sharif University of Technology
    Elsevier B.V  2021
    In the past few years, most studies have focused on smart substances that can respond to changes in the environment, as they can be appropriately applied in different fields, including biosensing, biotechnology, and drug delivery. Here, new fluorescent carbon dots (CDs) are synthesized by Terebinth by designing a simple and single-stage hydrothermal path, which facilitates the manufacture of CDs with no need for boring artificial methods, or using poisonous/costly solvents and starting substances. The method is used to concurrently form CDs and passivate their surface, which results in inherently emitted fluorescence. The study of the structure and optical features of the resulting CDs... 

    An Investigation on the Influence of EAF Slag Particle Size on AMD Neutralization Behavior in Static and Dynamic Slag Leaching Systems

    , Article Mine Water and the Environment ; Volume 34, Issue 2 , 2015 , Pages 204-212 ; 10259112 (ISSN) Alizadeh, A ; Shoushtari Zadeh Naseri, P ; Sharif University of Technology
    Springer Verlag  2015
    Steel slag, which contains basic oxides capable of generating high levels of alkalinity, may be used in leaching beds or leaching channels to neutralize acid mine drainage (AMD). In the present study, electric arc furnace (EAF) slag from the Pasargad Steel Complex was used to investigate the influence of slag particle size on AMD treatment. Three slag samples with different particle size distributions (coarse, mixed, fine) were prepared. Slag composition, pH variation, level of alkalinity, and specific surface area were measured and the surfaces of the slag particles was examined by scanning electron microscopy. In both dynamic and static leaching tests, there proved to be three stages: an... 

    Adaptive input-output linearization control of pH processes

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 27, Issue 3 , 2008 , Pages 25-35 ; 10219986 (ISSN) Nejati, A ; Shahrokhi, M ; Mehrabani, A ; Sharif University of Technology
    pH control is a challenging problem due to its highly nonlinear nature. In this paper the performances of two different adaptive global linearizing controllers (GLC) are compared. Least squares technique has been used for identifying the titration curve. The first controller is a standard GLC based on material balances of each species. For implementation of this controller a nonlinear state estimator is used. Some modifications are proposed to avoid the singularity of the observer gain. The second controller is designed based on the reduced state equation. Through computer simulations, it has been shown that the performances of the second GLC is superior and it is more robust to process... 

    Superabsorbency, pH-sensitivity and swelling kinetics of partially hydrolyzed chitosan-g-poly(acrylamide) hydrogels

    , Article Turkish Journal of Chemistry ; Volume 30, Issue 5 , 2006 , Pages 595-608 ; 13000527 (ISSN) Pourjavadi, A ; Mahdavinia, G.R ; Sharif University of Technology
    Acrylamide (AAm) monomer was directly grafted onto chitosan using ammonium persulfate (APS) as an initiator and methylenebisacrylamide (MBA) as a crosslinking agent under an inert atmosphere. Two factors affecting the swelling capacity of the obtained hydrogel, AAm and MBA concentrations, were studied. The polymer structures were characterized by FTIR spectroscopy. Water absorbencies of the hydrogels were compared between before and after the alkaline hydrolysis treatment. Saponification of chitosan-g-poly(acrylamide) (chitosan-g-PAAm) with a hot sodium hydroxide solution gave rise to a high water absorbency. Swelling of the hydrogel samples in saline solution (0.15 mol/L NaCl, CaCl2 and... 

    Synthesis of multilayered pH-responsive nanocapsules by using tolyltriazole as corrosion inhibitor and ZrO2 nanoparticles as core

    , Article Nano-Structures and Nano-Objects ; Volume 26 , 2021 ; 2352507X (ISSN) Fathabadi, H. E ; Ghorbani, M ; Mokarami Ghartavol, H ; Sharif University of Technology
    Elsevier B.V  2021
    Smart multilayered pH-sensitive nanocapsules were successfully fabricated using a Layer by Layer (LbL) process. The obtained products were characterized using FESEM, TEM, EDS and elemental mapping, zeta-potential, FTIR, TGA, SIMS and the Tafel polarization techniques. A 55% enhancement in ZrO2 particle size was detected in FESEM and TEM images with a corona view after the LbL process. EDS and elemental mapping analysis and measurements of zeta potential indicated the well-defined layered deposition. FTIR showed the electrostatic bonding between tolyltriazole (TTA) molecules and different overlapping layers. The thermal analysis and SIMS confirmed that 2.7% TTA loaded in nanocapsules. Tafel... 

    Entanglement wedge reconstruction and correlation measures in mixed states: Modular flows versus quantum recovery channels

    , Article Physical Review D ; Volume 104, Issue 4 , 2021 ; 24700010 (ISSN) Ghodrati, M ; Sharif University of Technology
    American Physical Society  2021
    In this work we study the nature of correlations among mixed states in the setup of two symmetric strips. We use various tools to determine how the bulk geometry could be reconstructed from the boundary mixed information. These tools would be the modular Hamiltonian and modular flow, operator product expansion (OPE) blocks, quantum recovery channels such as Petz map, Uhlmann holonomy, and Wilson lines. We comment on the similarities and connections between these approaches in our symmetric setup of a mixed system. Specially, we use parameters such as dissipation which is being modeled by the mass of graviton, and also the same sign charge of the two strips to find connections between these... 

    Modified carrageenan. 2. Hydrolyzed crosslinked κ -carrageenan-g-PAAm as a novel smart superabsorbent hydrogel with low salt sensitivity

    , Article Journal of Biomaterials Science, Polymer Edition ; Volume 15, Issue 12 , 2004 , Pages 1499-1511 ; 09205063 (ISSN) Hosseinzadeh, H ; Pourjavavdi, A ; Zohuriaan Mehr, M. J ; Sharif University of Technology
    A novel pH-responsive superabsorbing hydrogel based on κ-carrageenan (κC) was prepared through polyacrylamide crosslinking grafting followed by alkaline hydrolysis. The hydrogel structure was confirmed using FT-IR spectroscopy. The hydrolysis conditions were systematically optimized to obtain a hydrogel with maximum swelling capacity. Thus, the reaction variables, including the hydrolysis time and temperature, concentration of sodium hydroxide, amount of hydrogel hydrolyzed and post-neutralization pH, were optimized. The swelling measurements of the hydrogels were conducted in 0.15 M aqueous solutions of LiCl, NaCl, KCl, CaCl2 and AlCl3. As observed for the hydrolyzed hydrogel (H-carragPAM),... 

    Modified chitosan 4. Superabsorbent hydrogels from poly(acrylic acid-co-acrylamide) grafted chitosan with salt- and pH-responsiveness properties

    , Article European Polymer Journal ; Volume 40, Issue 7 , 2004 , Pages 1399-1407 ; 00143057 (ISSN) Mahdavinia, G. R ; Pourjavadi, A ; Hosseinzadeh, H ; Zohuriaan, M. J ; Sharif University of Technology
    Graft copolymerization of mixtures of acrylic acid (AA) and acrylamide (AAm) onto chitosan was carried out by using potassium persulfate (KPS) as a free radical initiator in the presence of methylenebisacrylamide (MBA) as a crosslinker. The effect of reaction variables, such as MBA concentration and AA/AAm ratio on the water absorbency capacity have been investigated. The polymer structures were confirmed by FTIR spectroscopy. Water absorbencies were compared for the hydrogels before and after alkaline hydrolysis. In the non-hydrolyzed hydrogel, enhanced water absorbency was obtained with increasing AA in monomer feed. However, after saponification, the sample with high AAm ratio exhibited... 

    Modified carrageenan. 4. Synthesis and swelling behavior of crosslinked ΚC-g-AMPS superabsorbent hydrogel with antisalt and pH-responsiveness properties

    , Article Journal of Applied Polymer Science ; Volume 98, Issue 1 , 2005 , Pages 255-263 ; 00218995 (ISSN) Pourjavadi, A ; Hosseinzadeh, H ; Mazidi, R ; Sharif University of Technology
    To synthesize a novel biopolymer-based superabsorbent hydrogel, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) was grafted onto kappa-carrageenan (ΚC) backbones. The graft copolymerization reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator, N,N,N′,N′-tetramethyl ethylenediamine (TMEDA) as an accelerator, and N,N′-methylene bisacrylamide (MBA) as a crosslinker. A proposed mechanism for ΚC-g-AMPS formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The affecting variables on swelling capacity, i.e., the initiator, the crosslinker, and the monomer concentration, as well as reaction temperature,... 

    Laboratory and Numerical Modeling of Hydraulic Behavior of Saturated Fine Grained Soils Dewatered by Electrokinetic Geosynthetic

    , M.Sc. Thesis Sharif University of Technology Shahsavand, Mohammad (Author) ; Pak, Ali (Supervisor) ; Shariatmadari, Nader (Co-Advisor)
    Most available methods which are well able to improve or dewater coarse soils have little success dealing with fine soils and clays and using these methods to dewater clays needs great amount of time and money. Electrokinetic Geosynthetic is one of new methods that have had a promising future. Regarding the importance and tremendous usage of dewatering in fine soils, the efficiency of electrokinetic geosynthetic method in dewatering fine soils has been taken under the consideration in this research. Following laboratory experimentation, numerical modeling of this process has been done. In this research some laboratory test has been done on kaolinite clay and the effects of pH of specimen,... 

    Performance of a single chamber microbial fuel cell at different organic loads and pH values using purified terephthalic acid wastewater

    , Article Journal of Environmental Health Science and Engineering ; Volume 13, Issue 1 , April , 2015 ; 2052336X (ISSN) Marashi, S. K. F ; Kariminia, H. R ; Sharif University of Technology
    BioMed Central Ltd  2015
    Background: Purified terephthalic acid (PTA) wastewater from a petrochemical complex was utilized as a fuel in the anode of a microbial fuel cell (MFC). Effects of two important parameters including different dilutions of the PTA wastewater and pH on the performance of the MFC were investigated. Methods: The MFC used was a membrane-less single chamber consisted of a stainless steel mesh as anode electrode and a carbon cloth as cathode electrode. Both power density and current density were calculated based on the projected surface area of the cathode electrode. Power density curve method was used to specify maximum power density and internal resistance of the MFC. Results: Using 10-times,... 

    Hydrazine-modified starch coated magnetic nanoparticles as an effective pH-responsive nanocarrier for doxorubicin delivery

    , Article Journal of Industrial and Engineering Chemistry ; Volume 39 , 2016 , Pages 203-209 ; 1226086X (ISSN) Zohreh, N ; Hosseini, S. H ; Pourjavadi, A ; Sharif University of Technology
    Korean Society of Industrial Engineering Chemistry  2016
    A novel, magnetic nanocarrier was successfully synthesized through a facile and economical producer in which Fe3O4 magnetic nanoparticles were coated by starch-g-poly (methyl methacrylate-co-PEG-acrylamide). The surface of nanocarrier was then modified by hydrazine to preparation of a pH-responsive carrier. The resulted nanocarrier was applied for delivery of doxorubicin (DOX) as an effective anti-cancer drug. DOX was reacted with hydrazine linkage on the surface of nanocarrier to form hydrazone bond. Due to the presence of numerous hydrazine groups on the surface of magnetic nanocarrier large amounts of DOX was loaded onto the carrier (327 mg g−1). © 2016 The Korean Society of Industrial... 

    An integrated performance and robust stability based multi-model control of nonlinear systems: a PH neutralization reactor

    , Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 679-684 ; 9781509059638 (ISBN) Ahmadi, M ; Haeri, M ; Sharif University of Technology
    This paper presents a new multi-model control scheme which integrates the stability and performance requirements to determine the nominal local models. Gap metric and stability margin concepts are applied to measure the distance between the local models and to grid the operation range of nonlinear system, respectively. The minimization of the integral of time absolute error is included as performance criterion. Furthermore, the multi-model decomposition and local controllers design are integrated in an optimization problem which provides avoidance of the redundancy issue. A fixed PI structure is considered as the local controllers to simplify the global multi-model controller structure....