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Total 22 records

    Influence of surface-modified nanoparticles on the hydrodynamics of rising bubbles

    , Article Chemical Engineering and Technology ; Volume 44, Issue 3 , 2021 , Pages 513-520 ; 09307516 (ISSN) Fayzi, P ; Bastani, D ; Lotfi, M ; Miller, R ; Sharif University of Technology
    Wiley-VCH Verlag  2021
    Abstract
    Local velocities of bubbles rising in four different nanosilica solutions were investigated experimentally. Also, the density, viscosity, and surface tension of fumed nanosilica and modified nanosilica solutions were measured. Heat treatment and chemical functionalization were used to modify the properties of silica nanoparticles. It was found that the addition of nanosilica affected the hydrodynamics of the rising bubble by increasing the drag friction at the interface. However, environmentally responsive nanosilica particles behaved like surfactant molecules, due to the interfacial activity of hydrophilic and hydrophobic chains. Silica nanoparticles coated with both hydrophilic and... 

    Facile synthesis of cauliflower-like hydrophobically modified polyacrylamide nanospheres by aerosol-photopolymerization

    , Article European Polymer Journal ; Volume 83 , 2016 , Pages 323-336 ; 00143057 (ISSN) Shaban, M ; Ramazani, S. A. A ; Ahadian, M. M ; Tamsilian, Y ; Weber, A. P ; Sharif University of Technology
    Elsevier Ltd  2016
    Abstract
    Amphiphilic copolymers consist of hydrophilic and hydrophobic monomer units have attracted great technological attention recently, owing to their unique properties and their ability to stabilize various interfaces in aqueous systems. This paper presents a novel and facile approach to produce spherical polyacrylamide, polystyrene and hydrophobically modified polyacrylamide (HM-PAM), as one of the most important type of amphiphilic copolymers, using a continuous aerosol-photopolymerization for the first time. To this end, the monomer droplets were generated by an atomizer, then photopolymerization was initiated ‘‘in flight’’ by ultraviolet (UV) irradiation of the aerosol monomer droplets... 

    An exploratory study on application of various classification models to distinguish switchable-hydrophilicity solvents based on 3D-descriptors

    , Article Separation Science and Technology (Philadelphia) ; Volume 56, Issue 5 , 2021 , Pages 961-969 ; 01496395 (ISSN) Shiri, M ; Shiri, F ; Sharif University of Technology
    Bellwether Publishing, Ltd  2021
    Abstract
    A set of solvents were classified into the switchable-hydrophilicity solvents (SHSs) and non-switchable-hydrophilicity solvents based on forming or not forming a biphasic mixture with water. SHSs have been developed to make the reaction and product separation processes easier. Herein, three classifier algorithms and various feature selection techniques relay on 3D-molecular descriptors to characterize chemicals and forecast their classes were employed. Cfs-SVM method was employed to perform a classification study. The importance of this study helps to understand more about the presence of hydrophobic groups, their position, and their shape in the molecule. © 2020 Taylor & Francis Group, LLC  

    Hydrophobic nanocarriers embedded in a novel dual-responsive poly(N-isopropylacrylamide)/chitosan/(cyclodextrin) nanohydrogel

    , Article Journal of Polymer Research ; Volume 20, Issue 10 , 2013 ; 1572-8935 (Online ISSN) Bashari, A ; Hemmatinejad, N ; Pourjavadi, A ; Sharif University of Technology
    2013
    Abstract
    The incorporation of modified β-cyclodextrin (β-CD) into a poly(N-isopropylacrylamide) (PNIPAAm)/chitosan (PNCS) nanohydrogel was studied. β-CD was functionalized with acrylic groups, with different numbers of vinyl bonds added per β-CD molecule. The surfactant-free dispersion polymerization (SFDP) semi-batch method was used to synthesize the nanohydrogel. Increasing the number of vinyl groups per β-CDAC (β-CD acrylate) molecule induced the formation of smaller nanogels with diameters ranging from 142 to 68 nm. The cyclodextrin-modified dual-responsive nanogels obtained presented an LCST (lower critical solution temperature) in aqueous medium at around 31 C. The incorporation of β-CDAC into... 

    Stimulus-responsive liposomes as smart nanoplatforms for drug delivery applications

    , Article Nanotechnology Reviews ; 2017 ; 21919089 (ISSN) Sahandi Zangabad, P ; Mirkiani, S ; Shahsavari, S ; Masoudi, B ; Masroor, M ; Hamed, H ; Jafari, Z ; Davatgaran Taghipour, Y ; Hashemi, H ; Karimi, M ; Hamblin, M. R ; Sharif University of Technology
    Abstract
    Liposomes are known to be promising nanoparticles (NPs) for drug delivery applications. Among different types of self-assembled NPs, liposomes stand out for their non-toxic nature, and their possession of dual hydrophilic-hydrophobic domains. Advantages of liposomes include the ability to solubilize hydrophobic drugs, the ability to incorporate different hydrophilic and lipophilic drugs at the same time, lessening the exposure of host organs to potentially toxic drugs and allowing modification of the surface by a variety of different chemical groups. This modification of the surface, or of the individual constituents, may be used to achieve two important goals. Firstly, ligands for active... 

    Stimulus-responsive liposomes as smart nanoplatforms for drug delivery applications

    , Article Nanotechnology Reviews ; Volume 7, Issue 1 , 2018 , Pages 95-122 ; 21919089 (ISSN) Sahandi Zangabad, P ; Mirkiani, S ; Shahsavari, S ; Masoudi, B ; Masroor, M ; Hamed, H ; Jafari, Z ; Davatgaran Taghipour, Y ; Hashemi, H ; Karimi, M ; Hamblin, M. R ; Sharif University of Technology
    Walter de Gruyter GmbH  2018
    Abstract
    Liposomes are known to be promising nanoparticles (NPs) for drug delivery applications. Among the different types of self-assembled NPs, liposomes stand out for their non-toxic nature and their possession of dual hydrophilic-hydrophobic domains. The advantages of liposomes include the ability to solubilize hydrophobic drugs, the ability to incorporate different hydrophilic and lipophilic drugs at the same time, lessening the exposure of host organs to potentially toxic drugs and allowing modification of the surface by a variety of different chemical groups. This modification of the surface, or of the individual constituents, may be used to achieve two important goals. First, ligands for... 

    Inverse emulsion polymerization of triple monomers of acrylamide, maleic anhydride, and styrene to achieve highly hydrophilichydrophobic 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... 

    An exploratory study on application of various classification models to distinguish switchable-hydrophilicity solvents based on 3D-descriptors

    , Article Separation Science and Technology (Philadelphia) ; 2020 Shiri, M ; Shiri, F ; Sharif University of Technology
    Taylor and Francis Inc  2020
    Abstract
    A set of solvents were classified into the switchable-hydrophilicity solvents (SHSs) and non-switchable-hydrophilicity solvents based on forming or not forming a biphasic mixture with water. SHSs have been developed to make the reaction and product separation processes easier. Herein, three classifier algorithms and various feature selection techniques relay on 3D-molecular descriptors to characterize chemicals and forecast their classes were employed. Cfs-SVM method was employed to perform a classification study. The importance of this study helps to understand more about the presence of hydrophobic groups, their position, and their shape in the molecule. © 2020, © 2020 Taylor & Francis... 

    Superior anti-biofouling properties of mPEG-modified polyurethane networks via incorporation of a hydrophobic dangling chain

    , Article Progress in Organic Coatings ; Volume 158 , September , 2021 ; 03009440 (ISSN) Golmohammadian Tehrani, A ; Makki, H ; Ghaffarian Anbaran, R ; Vakili, H ; Ghermezcheshme, H ; Zandi, N ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    PEG-modification is a proven method to enhance the hydrophilicity, protein resistance, and anti-biofouling properties of polymer coatings. It is considered as the gold standard interfacial modification technique such that the higher PEG content, the higher hydrophilicity, and lower protein adsorption, i.e., the initial stage of the biofouling process. Nevertheless, increasing the PEG content causes a higher water uptake, which declines the polymer mechanical strength and increases its hydrolytic degradation rate. Thus, an effective strategy to produce a limited-water-absorbing PEG-modified polymer is to force the majority of PEG molecules to migrate towards the interfacial region while the... 

    Wettability properties of PTFE/ZnO nanorods thin film exhibiting UV-resilient superhydrophobicity

    , Article Applied Surface Science ; Volume 341 , 2015 , Pages 92-99 ; 01694332 (ISSN) Bayat, A ; Ebrahimi, M ; Nourmohammadi, A ; Moshfegh, A. Z ; Sharif University of Technology
    Elsevier  2015
    Abstract
    In this research, initially anodization process was used to fabricate ZnO nanorods on Zn substrate and then RF sputtering technique was applied to grow a thin layer of polytetrafluoroethylene (PTFE, Teflon) on the coated ZnO nanorods for producing a superhydrophobic surface. According to scanning electron microscopy (SEM) observations, ZnO nanorods were formed with average diameter and length of about ∼180 nm and 14 μm, respectively. Superhydrophilic property of ZnO nanorods and superhydrophobic property of PTFE/ZnO nanorods was investigated by water contact angle (WCA) measurements. It was found that the contact angle varied with the PTFE deposition time. The highest contact angle... 

    Environmentally responsive surface-modified silica nanoparticles for enhanced oil recovery

    , Article Journal of Nanoparticle Research ; Volume 18, Issue 9 , 2016 ; 13880764 (ISSN) Behzadi, A ; Mohammadi, A ; Sharif University of Technology
    Springer Netherlands 
    Abstract
    Environmentally responsive surface-modified nanoparticles are colloidal nanoparticles coated with, at least, two physicochemically distinct surface groups. Recent advances in the synthesis and production of nanoparticles have enabled the production of environmentally responsive surface-modified nanoparticles with both hydrophilic and hydrophobic surface groups. These nanoparticles act like colloidal surfactants. In this paper, environmentally responsive surface-modified silica nanoparticles are synthesized and used for enhancement of oil recovery. For this purpose, silica nanoparticles are coated with polyethylene glycol chains as hydrophilic agent and propyl chains as hydrophobic agent at... 

    Plasma based surface modication of poly (dimethylsiloxane) electrospun membrane proper for organ-on-a-chip applications

    , Article Scientia Iranica ; Volume 26, Issue 2 , 2019 , Pages 808-814 ; 10263098 (ISSN) Kiyoumarsioskouei, A ; Saidi, M. S ; Moghadas, H ; Firoozabadi, B ; Sharif University of Technology
    Sharif University of Technology  2019
    Abstract
    Electrospun porous membrane; Superhydrophilic surfaces; Superhydrophobic surfaces; Cell culture; Organ on a chip; Flexible membrane; Strong membrane; Surface modications  

    Plasma based surface modication of poly (dimethylsiloxane) electrospun membrane proper for organ-on-a-chip applications

    , Article Scientia Iranica ; Volume 26, Issue 2 , 2019 , Pages 808-814 ; 10263098 (ISSN) Kiyoumarsioskouei, A ; Saidi, M. S ; Moghadas, H ; Firoozabadi, B ; Sharif University of Technology
    Sharif University of Technology  2019
    Abstract
    onstructing of the scaffolds for cell culture applications has long been of interest for engineering researchers and biologist. In this study, a novel process is utilized for construction of suitable membrane with a high mechanical strength and appropriate surface behavior. Poly (dimethylsiloxane) (PDMS) is electrospun into fine fibers using poly (methyl methacrylate) (PMMA) as the carrier polymer in different weight ratios. Since the surface behavior of all PDMS substrates is moderately hydrophobic (120 < contact angle (CA) < 150), the electrospun membranes with higher PDMS ratios show slightly higher hydrophilicity. Direct plasma treatment is utilized to change the interfacial wettability... 

    Dissolution and conformational behavior of functionalized cellulose chains in the bulk, aqueous and non-aqueous media: A simulation study

    , Article Carbohydrate Research ; Volume 496 , October , 2020 Koochaki, A ; Moghbeli, M. R ; Rasouli, S ; Gharib Zahedi, M. R ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    In the present study, we employ all-atom molecular dynamics simulations to investigate the dynamic behaviors and structural properties of the native and modified cellulose chains in the bulk, aqueous, and organic media. Particular attention has been directed to the role of different hydrophobic and hydrophilic functional groups as linear and branched aliphatic and also cyclic pendent groups on the solubility and packing of the cellulose chain. The various properties related to density profile, mean squared displacement, intramolecular entropy, radius of gyration, and radial distribution function were calculated. The results showed that the chain tendency toward crystallinity decreased when... 

    Graphene oxide functionalized with oxygen-rich polymers as a pH-sensitive carrier for co-delivery of hydrophobic and hydrophilic drugs

    , Article Journal of Drug Delivery Science and Technology ; Volume 56 , 2020 Pourjavadi, A ; Asgari, S ; Hosseini, S. H ; Sharif University of Technology
    Editions de Sante  2020
    Abstract
    In this work, a novel carrier based-on modified graphene oxide was designed for co-delivery of hydrophobic and hydrophilic anticancer drugs (curcumin (Cur) and doxorubicin (DOX) as the model of drugs). The hydroxyl groups at the edges of graphene oxide (GO) sheets were used as the initiation sites for growing poly(epichlorohydrin) (PCH) chains. Then, hyperbranched polyglycerol (HPG) was grafted on the hydroxyl end groups of PCH (PCH-g-HPG). Pendant chlorines in the main chain of GO-PCH-g-HPG were replaced with hydrazine. The modification of GO sheets with oxygen-rich polymers increased water solubility of graphene oxide. Doxorubicin was loaded onto the nanocarrier by covalent bonding with... 

    Effect of physico-chemical properties of nanoparticles on their intracellular uptake

    , Article International Journal of Molecular Sciences ; Volume 21, Issue 21 , 2020 , Pages 1-20 Sabourian, P ; Yazdani, G ; Ashraf, S. S ; Frounchi, M ; Mashayekhan, S ; Kiani, S ; Kakkar, A ; Sharif University of Technology
    MDPI AG  2020
    Abstract
    Cellular internalization of inorganic, lipidic and polymeric nanoparticles is of great significance in the quest to develop effective formulations for the treatment of high morbidity rate diseases. Understanding nanoparticle–cell interactions plays a key role in therapeutic interventions, and it continues to be a topic of great interest to both chemists and biologists. The mechanistic evaluation of cellular uptake is quite complex and is continuously being aided by the design of nanocarriers with desired physico-chemical properties. The progress in biomedicine, including enhancing the rate of uptake by the cells, is being made through the development of structure–property relationships in... 

    CaTiO3/α-TCP coatings on CP-Ti prepared via electrospinning and pulsed laser treatment for in-vitro bone tissue engineering

    , Article Surface and Coatings Technology ; Volume 401 , 2020 Yadi, M ; Esfahani, H ; Sheikhi, M ; Mohammadi, M ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    In this study, the in-vitro bone regeneration ability of commercial pure titanium (CP-Ti) surface modified via electrospun polyvinylidene/hydroxyapatite (PVP/HA) masking and subsequent Nd-YAG pulsed laser treatment was investigated. The ratio of HA to PVP played a significant role in achieving a perfect homogenous mask on the CP-Ti. In the laser treatment process, the parameter of area scanning speed (ASS) had an important influence on the final surface morphology. A favorable range was defined for this parameter where these two conditions were satisfied: no PVP remaining and no severe substrate melting. Within a favorable range of ASS, as decreasing ASS exchanged the surface structure from... 

    The effect of water vapor on the performance of commercial polyphenylene oxide and Cardo-type polyimide hollow fiber membranes in CO2/CH4 separation applications

    , Article Journal of Membrane Science ; Volume 285, Issue 1-2 , 2006 , Pages 265-271 ; 03767388 (ISSN) Pourafshari Chenar, M ; Soltanieh, M ; Matsuura, T ; Tabe Mohammadi, A ; Khulbe, K. C ; Sharif University of Technology
    2006
    Abstract
    The effects of water vapor on CO2/CH4 separation using commercially available poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and Cardo-type polyimide hollow fiber membranes were investigated. Pure methane and CO2/CH4 mixture permeation experiments were carried out in the absence and presence of water vapor (60% RH). Pure methane permeance decreased in the presence of water vapor for both membrane types. The decrease was 28% for hydrophilic Cardo-type polyimide and 6% for hydrophobic PPO membranes. The decline in the permeance was also observed for CO2/CH4 mixture separation through both membranes. However, selectivities of the two membranes were affected differently by water vapor. The... 

    Lipid membranes with transmembrane proteins in shear flow

    , Article Journal of Chemical Physics ; Volume 132, Issue 2 , 2010 ; 00219606 (ISSN) Khoshnood, A ; Noguchi, H ; Gompper, G ; Sharif University of Technology
    Abstract
    The effects of embedded proteins on the dynamical properties of lipid bilayer membranes are studied in shear flow. Coarse-grained molecular simulations are employed, in which lipids are modeled as short polymers consisting of hydrophilic head groups and hydrophobic tail monomers; similarly, transmembrane proteins are modeled as connected hydrophobic double- or triple-chain molecules with hydrophilic groups at both ends. In thermal equilibrium, rigid proteinlike molecules aggregate in a membrane of flexible lipids, while flexible proteins do not aggregate. In shear flow parallel to the membrane, the monolayers of lipid bilayer slide over each other. The presence of transmembrane proteins... 

    Silane functionalization of nanodiamond for polymer nanocomposites-effect of degree of silanization

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 506 , 2016 , Pages 254-263 ; 09277757 (ISSN) Hajiali, F ; Shojaei, A ; Sharif University of Technology
    Elsevier B.V  2016
    Abstract
    The silanization of nanodiamond (ND) was successfully carried out by using the esterification reaction of hydrolyzed vinyltrimethoxysilane (VTS) in alcoholic solution. The surface carboxylic group of ND was first enhanced by thermal oxidation to increase the degree of esterification reaction. The extent of silane functionalization of ND was controlled by varying the weight ratio of VTS and oxidized ND (oxND), from 2:1 to 10:1 (w/w) in the functionalization reaction medium. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) revealed that the highest degree of silanization occurred at VTS/oxND of 5:1 (w/w), while more silane concentrations resulted in...