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Total 84 records

    Optimization of Encapsulation of Probiotic Living Cells

    , M.Sc. Thesis Sharif University of Technology Sajjadi Dehkordi, Sahar (Author) ; Alemzadeh, Iran (Supervisor)
    Abstract
    In the recent year, there has been a rising interest in producing functional foods containing encapsulated probiotic bacteria according to their perceived health benefits. Probiotics are feed and food supplements that beneficially affect the host’s health. The term “probiotic” includes a large range of microorganisms, mainly lactic acid bacteria. Because they can stay alive until the intestine and provide health beneficial effects like lowering cholesterol, improving lactose tolerance and preventing some cancers like colon cancer on the host health. It has been recommended that the viability of probiotics should be at least 107 CFU/ml of product at time of consumptions to provide selective... 

    Chemometric-based determination of polycyclic aromatic hydrocarbons in aqueous samples using ultrasound-assisted emulsification microextraction combined to gas chromatography-mass spectrometry

    , Article Journal of Chromatography A ; Volume 1413 , September , 2015 , Pages 117-126 ; 00219673 (ISSN) Ahmadvand, M ; Sereshti, H ; Parastar, H ; Sharif University of Technology
    Elsevier  2015
    Abstract
    In the present research, ultrasonic-assisted emulsification-microextraction (USAEME) coupled with gas chromatography-mass spectrometry (GC-MS) has been proposed for analysis of thirteen environmental protection agency (EPA) polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Tetrachloroethylene was selected as extraction solvent. The main parameters of USAEME affecting the efficiency of the method were modeled and optimized using a central composite design (CCD). Under the optimum conditions (9 μL for extraction solvent, 1.15% (w/v) NaCl (salt concentration) and 10min for ultrasonication time), preconcentration factor (PF) of the PAHs was in the range of 500-950. In order to have a... 

    Prediction of flooding in a pulsed packed column for continuous pertraction of dysprosium by an emulsion liquid membrane

    , Article Chemical Engineering and Processing - Process Intensification ; Volume 169 , 2021 ; 02552701 (ISSN) Sadehlari, F ; Bastani, D ; Safdari, J ; Raji, M ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    For the first time, Dysprosium was extracted by the novel method of emulsion liquid membrane in a pulsed packed column in a continuous process. Emulsion liquid membrane (ELM) was comprised of D2EHPA (di-2-ethylhexylphosphoric acid) as carrier and Span 80 (Polysorbate 80) as the surfactant in kerosene as the diluent and nitric acid as internal phase. In this work, the packed column was characterized from a hydrodynamic point of view including flooding condition and holdup at flooding points. Operational parameters affecting the flooding points, such as pulsation intensity and flow rate of continuous and dispersed phases have been studied. It was found that increase in pulsation intensity up... 

    Analysis of bioactive constituents of saffron using ultrasonic assisted emulsification microextraction combined with high-performance liquid chromatography with diode array detector: A chemometric study

    , Article RSC Advances ; Volume 5, Issue 33 , 2015 , Pages 26246-26254 ; 20462069 (ISSN) Chaharlangi, M ; Parastar, H ; Malekpour, A ; Sharif University of Technology
    Royal Society of Chemistry  2015
    Abstract
    In recent years, there has been an increasing interest in the analysis of the major active components of saffron owing to their significant role in various industries, such as food, medicine and perfume. In other words, analysis of the major active components of saffron can give complete information about its chemical composition, which can be used as a reliable index for the quality control of different saffron samples (i.e., natural and commercial). The aim of the present work was to develop a simple, low cost, efficient and comprehensive strategy for the extraction and analysis of the bioactive components of saffron. In this regard, ultrasonic-assisted solvent extraction (UASE) combined... 

    Evaluation of a recycling bioreactor for biosurfactant production by Pseudomonas aeruginosa MR01 using soybean oil waste

    , Article Journal of Chemical Technology and Biotechnology ; Volume 91, Issue 5 , 2016 , Pages 1368-1377 ; 02682575 (ISSN) Bagheri Lotfabad, T ; Ebadipour, N ; Roostaazad, R ; Sharif University of Technology
    John Wiley and Sons Ltd 
    Abstract
    This study deals with the large-scale production of biosurfactant from soybean oil soapstock by Pseudomonas aeruginosa MR01. The production of biosurfactant was carried out in a newly designed bioreactor equipped with recycling flow under three operational conditions. Kinetic studies were conducted at both shake flask and 5-L bioreactor scales during fermentation in a soapstock medium. Mathematical equations were developed to model the kinetic patterns at both scales. RESULT: Statistical analyses demonstrated the goodness of fit, with regression r-squared, R2, between 0.97and 0.99 for different models. Furthermore, biosurfactant concentration in the bioreactor including the recycling flow,... 

    Evaluation of chemicals interaction with heavy crude oil through water/oil emulsion and interfacial tension study

    , Article Energy and Fuels ; Vol. 27, issue. 10 , September , 2013 , p. 5852-5860 ; ISSN: 08870624 Dehghan, A. A ; Masihi, M ; Ayatollahi, S ; Sharif University of Technology
    Abstract
    A newly-designed surfactant was formulated to tolerate the harsh conditions of oil reservoirs, including high salinity of the formation brine and temperature. The specific emulsion and interfacial tension (IFT) behavior of this new surface active agent were investigated by performing emulsion stability tests, emulsion size analysis, and IFT behavior in the presence of four different types of alkalis. Image processing was utilized to analyze the droplet size distribution using microscopic images of the samples. The results show that depending on the composition of the mixtures, the optimum phase region and interfacial tension behavior change considerably. Solutions containing a higher... 

    Performance investigation of a four stroke diesel engine, using water-based ferrofluid as an additive

    , Article ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011, 11 November 2011 through 17 November 2011 ; Volume 4, Issue PARTS A AND B , November , 2011 , Pages 1339-1343 ; 9780791854907 (ISBN) Daneshvar, F ; Jahani, N ; Shafii, M. B ; ASME ; Sharif University of Technology
    Abstract
    In this experimental study, a four stroke diesel engine was conducted to investigate the effect of adding water-based ferrofluid to diesel fuel on engine performance. To our knowledge, Magnetic nanoparticles had not been used before. To this end, emulsified diesel fuels of 0, 0.4, and 0.8 water-based ferrofluid/Diesel ratios by volume were used as fuel. The ferrofluid used in this study was a handmade water-based ferrofluid prepared by the authors. The results show that adding water-based ferrofluid to diesel fuel has a perceptible effect on engine performance, increasing the brake thermal efficiency relatively up to 12%, and decreasing the brake specific fuel consumption relatively up to... 

    Dispersed phase holdup in a pulsed disc and doughnut extraction column

    , Article Brazilian Journal of Chemical Engineering ; Volume 28, Issue 2 , June , 2011 , Pages 313-323 ; 01046632 (ISSN) Torab Mostaedi, M ; Jalilvand, H ; Outokesh, M ; Sharif University of Technology
    2011
    Abstract
    Dispersed phase holdup has been measured in a 76 mm diameter pulsed disc and doughnut extraction column for three different liquid-liquid systems. The effects of operational variables such as pulsation intensity and dispersed and continuous phase flow rates on holdup have been investigated and found to be significant. The existence of three different operational regimes, namely mixer-settler, dispersion, and emulsion regimes, was observed when the energy input was changed. The results indicated that the characteristic velocity approach is applicable to this type of extraction column for analysis of holdup in the transition and emulsion regions. Empirical correlations are derived for... 

    Improvement in flux and antifouling properties of PVC ultrafiltration membranes by incorporation of zinc oxide (ZnO) nanoparticles

    , Article Separation and Purification Technology ; Volume 156 , 2015 , Pages 299-310 ; 13835866 (ISSN) Rabiee, H ; Vatanpour, V ; Davood Abadi Farahani, M. H ; Zarrabi, H ; Sharif University of Technology
    Elsevier  2015
    Abstract
    In this study, modification of polyvinyl chloride (PVC) ultrafiltration membranes with zinc oxide (ZnO) nanoparticle addition was taken into consideration. The ZnO at five different weights was added to the polymeric solution, and the membranes were fabricated by the phase inversion method using water as a nonsolvent and PEG 6 kDa as a pore former additive. The results showed that the pure water flux of the modified membranes increased up to 3 wt% ZnO addition, which was the optimized amount of the nanoparticle addition in this study. Also, at 3 wt% ZnO addition, flux recovery ratio reached from 69% to above 90%, indicated that the nanocomposite membranes were less susceptible to be fouled.... 

    An experimental study on the effect of ultrasonication on thermal conductivity of ferrofluid loaded with carbon nanotubes

    , Article Thermochimica Acta ; Volume 617 , October , 2015 , Pages 102-110 ; 00406031 (ISSN) Shahsavar, A ; Salimpour, M. R ; Saghafian, M ; Shafii, M. B ; Sharif University of Technology
    Elsevier  2015
    Abstract
    Nanofluids containing Fe3O4 and carbon nanotubes nanoparticles emulsified and dispersed using gum arabic (GA) and tetramethylammonium hydroxide (TMAH) were made and characterized for potential use as heat transfer fluids. Due to the interaction between the TMAH and GA molecules, the magnetic nanoparticles and CNTs were physically adsorbed. This paper reports an experimental work on the effect of ultrasonication on thermal conductivity of this aqueous suspension. The characterization and surface morphology of the dried samples were studied by using XRD and TEM measurements. Experiments were conducted in the magnetic nanoparticles mass concentration range 0.494-2.428%,... 

    Simulation and control of monomer conversion in a continuous emulsion polymerization reactor

    , Article IFAC Proceedings Volumes (IFAC-PapersOnline), 7 June 2015 through 10 June 2015 ; Volume 48, Issue 8 , 2015 , Pages 315-320 ; 14746670 (ISSN) Barazandegan, M ; Shahrokhi, M ; Abedini, H ; Vafa, E ; Guay, M ; Gopaluni, B ; Huang, B ; Findeisen, R ; Sharif University of Technology
    IFAC Secretariat  2015
    Abstract
    A detailed pseudo-bulk model has been used for prediction of conversion and particle size distribution (PSD) of vinyl acetate in a continuous emulsion polymerization reactor. Finite volume (FV) and moment techniques are applied for solving population balance equation under continuous operation. It is found that both methods can predict sustained oscillations in the monomer conversion, however the FV method matches the experimental data better than the moment method. The monomer conversion and free surfactant concentration are controlled via two single control loops. In this work, a new control strategy for controlling monomer conversion has been proposed. It has been shown that monomer... 

    Theoretical and experimental investigations of the inverse emulsion polymerization of acrylamide

    , Article Journal of Applied Polymer Science ; Volume 132, Issue 22 , February , 2015 ; 00218995 (ISSN) Abdi, A ; Shahrokhi, M ; Ahmad Ramazani, S. A ; Vafa, E ; Sharif University of Technology
    John Wiley and Sons Inc  2015
    Abstract
    In this study, the inverse emulsion polymerization modeling of polyacrylamide with population balance equations (PBEs) was performed. The PBEs were derived on the basis of the zero-one kinetic model. The effects of the surfactant steric barrier and surfactant reaction with radicals, including monomeric radicals, on the radical entry rate into the particle were taken into account. In the modified model, the coagulation phenomenon was included through consideration of the effects of forces not included in the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory; these include hydration and steric forces in addition to DLVO forces. The effects of the surfactant and initiator concentrations on... 

    Design, fabrication, and characterization of novel porous conductive scaffolds for nerve tissue engineering

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 64, Issue 18 , 2015 , Pages 969-977 ; 00914037 (ISSN) Baniasadi, H ; Ahmad Ramazani, S. A ; Mashayekhan, S ; Farani, M. R ; Ghaderinezhad, F ; Dabaghi, M ; Sharif University of Technology
    Taylor and Francis Inc  2015
    Abstract
    Highly conductive polypyrrole/graphene (PYG) nanocomposite was synthesized with chemical oxidation process via emulsion polymerization and used for the preparation of novel porous conductive gelatin/chitosan-based scaffolds. The effect of PYG loading on various properties of scaffolds was investigated. The obtained results indicated that by introducing PYG into the polymeric matrix, the porosity and swelling capacity decreased while electrical conductivity and Young's modulus demonstrated increasing trend. The in vitro biodegradation test revealed that pure gelatin/chitosan matrix lost 80% of its weight after six weeks in the presence of lysozyme whilst the biodegradation rate was... 

    Worm-like micelles:a new approach for heavy oil recovery from fractured systems

    , Article Canadian Journal of Chemical Engineering ; Volume 93, Issue 5 , 2015 , Pages 951-958 ; 00084034 (ISSN) Kianinejad, A ; Saidian, M ; Mavaddat, M ; Ghazanfari, M. H ; Kharrat, R ; Rashtchian, D ; Sharif University of Technology
    Wiley-Liss Inc  2015
    Abstract
    In this work, a new type of flooding system, "worm-like micelles", in enhanced heavy oil recovery (EOR) has been introduced. Application of these types of surfactants, because of their intriguing and surprising behaviour, is attractive for EOR studies. Fundamental understanding of the sweep efficiencies as well as displacement mechanisms of this flooding system in heterogeneous systems especially for heavy oils remains a topic of debate in the literature. Worm-like micellar surfactant solutions are made up of highly flexible cylindrical aggregates. Such micellar solutions display high surface activity and high viscoelasticity, making them attractive in practical applications for EOR. In this... 

    Phase behavior and rheology of emulsions in an alkaline/cosolvent/crude oil/brine system

    , Article Petroleum Science and Technology ; Volume 34, Issue 3 , 2016 , Pages 207-215 ; 10916466 (ISSN) Bahman Abadi, H ; Hemmati, M ; Shariat Panahi, H ; Masihi, M ; Karam Beigi, M. S ; Sharif University of Technology
    Taylor and Francis Inc 
    Abstract
    Phase behavior of active crude oil/alkaline was systematically studied in the presence of cosolvents. For this purpose, several factors have been considered: alkaline concentration, oil concentration, and type of brine. The best composition was used to generate emulsion for rheology and displacement tests. Furthermore, precipitation of alkaline was eliminated by its synergy with EDTA. Next, rheology of emulsion was analyzed by which a Power law model was developed that indicates non-Newtonian behavior of emulsion. Moreover, the viscosity of emulsion was reduced by the addition of cosolvent as well as by the increase of alkaline concentration. Finally, the best formulation (containing... 

    The effect of dispersed phase salinity on water-in-oil emulsion flow performance: A micromodel study

    , Article Industrial and Engineering Chemistry Research ; Volume 56, Issue 15 , 2017 , Pages 4549-4561 ; 08885885 (ISSN) Maaref, S ; Ayatollahi, S ; Rezaei, N ; Masihi, M ; Sharif University of Technology
    American Chemical Society  2017
    Abstract
    In this work, the effect of brine salinity on water-in-oil emulsion flow performance in porous media is studied as it imposes a significant challenge to oil production in the petroleum industry. A crude oil sample from an Iranian oilfield and synthetic brine with different salinities (40-140 g/L salt) are used. The results show that the emulsion viscosity and interfacial tension increase slightly with salinity, while they do not considerably affect the flow behavior. The emulsion stability analysis shows that larger w/o emulsion droplets are formed for higher brine salinity, which potentially block more pore spaces through straining and interception mechanisms. This phenomenon resulted in... 

    Spheroids-on-a-chip: recent advances and design considerations in microfluidic platforms for spheroid formation and culture

    , Article Sensors and Actuators, B: Chemical ; Volume 263 , 15 June , 2018 , Pages 151-176 ; 09254005 (ISSN) Moshksayan, K ; Kashaninejad, N ; Ebrahimi Warkiani, M ; Lock, J. G ; Moghadas, H ; Firoozabadi, B ; Saidi, M. S ; Nguyen, N. T ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    A cell spheroid is a three-dimensional (3D) aggregation of cells. Synthetic, in-vitro spheroids provide similar metabolism, proliferation, and species concentration gradients to those found in-vivo. For instance, cancer cell spheroids have been demonstrated to mimic in-vivo tumor microenvironments, and are thus suitable for in-vitro drug screening. The first part of this paper discusses the latest microfluidic designs for spheroid formation and culture, comparing their strategies and efficacy. The most recent microfluidic techniques for spheroid formation utilize emulsion, microwells, U-shaped microstructures, or digital microfluidics. The engineering aspects underpinning spheroid formation... 

    Inverse emulsion polymerization of triple monomers of acrylamide, maleic anhydride, and styrene to achieve highly hydrophilic–hydrophobic modified polyacrylamide

    , Article Journal of Applied Polymer Science ; Volume 136, Issue 29 , 2019 ; 00218995 (ISSN) Lalehgani, Z ; Ramazani S. A., A ; Tamsilian, Y ; Shirazi, M ; Sharif University of Technology
    John Wiley and Sons Inc  2019
    Abstract
    The purpose of this study was the production of copolymers and terpolymers with highly hydrophilic–hydrophobic properties, using inexpensive and available monomers as potential enhancing oil recovery (EOR) and water production control agents for high-temperature and high-salinity (HTHS) oil reservoirs. For this purpose, several copolymers and terpolymers with different molar percentage of acrylamide/styrene, acrylamide/maleic anhydride, and acrylamide/styrene/maleic anhydride were synthesized by the inverse emulsion polymerization technique. The presence of hydrophobic styrene and hydrophilic maleic anhydride monomers in the copolymer and terpolymer structure, provided some unique properties... 

    Encapsulation of food components and bioactive ingredients and targeted release

    , Article International Journal of Engineering, Transactions A: Basics ; Volume 33, Issue 1 , 2020 , Pages 1-11 Alemzadeh, I ; Hajiabbas, M ; Pakzad, H ; Sajadi Dehkordi, S ; Vossoughi, A ; Sharif University of Technology
    Materials and Energy Research Center  2020
    Abstract
    The potential utilization of encapsulation techniques in food, pharmaceutical and agricultural products preparation, presents a new alternative for complementary technologies such as targeting delivery vehicles and carriers for active food ingredients. Encapsulation could be accomplished by different techniques like: simple or complex coacervation, emulsification technique, phase separation, spray drying, spray chilling or spray cooling, extrusion coating, freeze drying, fluidized-bed coating, liposomal entrapment, centrifugal suspension separation, co-crystallization and molecular inclusion complexation. Encapsulation is a method by which one bioactive material or mixture of materials is... 

    The stability and surface activity of environmentally responsive surface-modified silica nanoparticles: the importance of hydrophobicity

    , Article Journal of Dispersion Science and Technology ; Volume 41, Issue 9 , 2020 , Pages 1299-1310 Ghaleh, V.R ; Mohammadi, A ; Sharif University of Technology
    Taylor and Francis Inc  2020
    Abstract
    In this study, the effect of hydrophobicity of environmentally responsive surface-modified silica nanoparticles on the stability and surface activity of the nanoparticles is examined. To this end, n-propyl, n-hexyl, or n-octyl chains and methoxy poly(ethylene glycol) chains at various quantities were coated covalently on the surface of silica nanoparticles to regulate the hydrophobicity of the responsive nanoparticles. Various experimental tools such as stability analysis, interfacial-tension and contact-angle measurements, and emulsion formation were performed to investigate the effect of hydrophobicity. It became evident that the presence of the hydrophobic agents influences considerably...