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Total 95 records

    Synthesis and superswelling behavior of carboxymethylcellulose-poly(sodium acrylate-co-acrylamide) hydrogel

    , Article Journal of Applied Polymer Science ; Volume 108, Issue 2 , 2008 , Pages 1142-1151 ; 00218995 (ISSN) Sadeghi, M ; Hosseinzadeh, H ; Sharif University of Technology
    2008
    Abstract
    In this paper, attention is paid to synthesis and swelling behavior of a superabsorbent hydrogel based carboxymethylcellulose (CMC) and polyacrylonitrile (PAN). The physical mixture of CMC and PAN was hydrolyzed in NaOH solution to yield hydrogel, CMC-poly(NaAA-co-AAm). During alkaline hydrolysis, the nitrile groups of PAN were completely converted to a mixture of hydrophilic carboxamide and carboxylate groups followed by in situ crosslinking of the grafted PAN chains. A proposed mechanism for hydrogel formation was suggested and the structure of the product was established using FTIR spectroscopy. The reaction variables affecting the swelling capacity of the hydrogel were systematically... 

    Morphology modification of the iron fumarate MIL-88A metal–organic framework using formic acid and acetic acid as modulators

    , Article European Journal of Inorganic Chemistry ; Volume 2018, Issue 18 , 2018 , Pages 1909-1915 ; 14341948 (ISSN) Bagherzadeh, E ; Zebarjad, S. M ; Madaah Hosseini, H. R ; Sharif University of Technology
    Wiley-VCH Verlag  2018
    Abstract
    Metal–organic frameworks (MOFs) are best known for their great structural diversity. The uniformity in the properties of MOFs is mainly governed by the size and morphology of the particles. In the present research, iron-MIL-88A was prepared by a modulator-assisted solvothermal method, and the role of modulating agents in the formation process of MOF particles was investigated. Acetic acid and formic acid were chosen as monoligand modulating agents. The changes in morphology and size distribution of the products were scrutinized by using SEM micrographs. Both modulators clearly interfered with the crystallization process through their attachment to the reactive sites. At low modulator... 

    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
    2006
    Abstract
    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... 

    Water dispersed magnetic nanoparticles (H2O-DMNPs) of γ-Fe2O3 for multicomponent coupling reactions: A green, single-pot technique for the synthesis of tetrahydro-4H-chromenes and hexahydroquinoline carboxylates

    , Article Tetrahedron Letters ; Volume 54, Issue 26 , 2013 , Pages 3344-3347 ; 00404039 (ISSN) Rostamnia, S ; Nuri, A ; Xin, H ; Pourjavadi, A ; Hosseini, S. H ; Sharif University of Technology
    2013
    Abstract
    Water dispersed magnetic nanoparticles (DMNPs) of γ-Fe 2O3 represent a simple and green catalyst for the rapid three-component synthesis of tetrahydro-4H-chromene and hexahydroquinoline carboxylate skeletons via single-pot domino Knoevenagel-Michael-cyclization reactions  

    Nanoscale graphene oxide sheets as highly efficient carbocatalysts in green oxidation of benzylic alcohols and aromatic aldehydes

    , Article Cuihua Xuebao/Chinese Journal of Catalysis ; Volume 38, Issue 4 , 2017 , Pages 745-757 ; 02539837 (ISSN) Sedrpoushan, A ; Heidari, M ; Akhavan, O ; Sharif University of Technology
    Science Press  2017
    Abstract
    Nanoscale graphene oxide (NGO) sheets were synthesized and used as carbocatalysts for effective oxidation of benzylic alcohols and aromatic aldehydes. For oxidation of alcohols in the presence of H2O2 at 80 °C, the NGOs (20% mass fraction) as carbocatalysts showed selectivity toward aldehyde. The rate and yield of this reaction strongly depended on the nature of substituents on the alcohol. For 4-nitrobenzyl alcohol, <10% of it was converted into the corresponding carboxylic acid after 24 h. By contrast, 4-methoxybenzyl alcohol and diphenylmethanol were completely converted into the corresponding carboxylic acid and ketone after only 9 and 3 h, respectively. The conversion rates for... 

    Solvent-free synthesis of 2-amino-3-aryl-5-substituted thiophenes as anti-inflammatory agents using KF-Al2O3 under microwave irradiation

    , Article Synthetic Communications ; Volume 38, Issue 12 , 2008 , Pages 2043-2053 ; 00397911 (ISSN) Saeidian, H ; Sadeghi, A ; Mirjafary, Z ; Matloubi Moghaddam, F ; Sharif University of Technology
    2008
    Abstract
    The synthesis of 2-amino-3-aryl-5-substituted thiophenes as anti-inflammatory agents catalyzed by KF-Al2O3 under microwave irradiation is reported. Copyright © Taylor & Francis Group, LLC  

    Carrageenan-g-poly(sodium acrylate)/kaolin superabsorbent hydrogel composites: Synthesis, characterisation and swelling behaviour

    , Article Polymers and Polymer Composites ; Volume 15, Issue 1 , 2007 , Pages 43-51 ; 09673911 (ISSN) Pourjavadi, A ; Hosseinzadeh, H ; Mahdavinia, G. R ; Zohuriaan Mehr, M. J ; Sharif University of Technology
    Rapra Technology Ltd  2007
    Abstract
    A novel superabsorbent hydrogel composite based on kappa-carrageenan (κC) was prepared by graft copolymerisation of acrylic acid (AA) in the presence of kaolin using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. The synthetic variables (i.e. AA, MBA and APS concentration, and the amount of kaolin) affecting the water absorbency of the resulting superabsorbent composite were studied. Evidence of grafting and kaolin interaction was obtained by comparing the FTIR spectra of the initial substrates and of the superabsorbent composite. A new absorption band at 1722 cm-1 in the composite spectrum confirmed the kaolin-organic polymer linkage.... 

    Extension of linear isotherm regularity to long chain primary, secondary and tertiary alcohols, ketones and 1-carboxylic acids by group contribution method

    , Article Fluid Phase Equilibria ; Volume 234, Issue 1-2 , 2005 , Pages 11-21 ; 03783812 (ISSN) Parsafar, G. A ; Kalantar, Z ; Sharif University of Technology
    2005
    Abstract
    In this work, the group contribution approach has been used in combination with the linear isotherm regularity (LIR) equation of state to estimate pvT properties of primary, secondary and tertiary alcohols, ketones and 1-carboxylic acid. In addition, the isothermal compressibility and thermal expansion coefficient of these compounds have been predicted. We assume each of these organic compounds as a hypothetical mixture of methyl, methylene and a functional group, in which the interaction potential of each pair is assumed to be the average effective pair potential. Then, the LIR equation of state (EOS) has been extended to such a hypothetical mixture. Three basic compounds, namely propane,... 

    The separation of cadmium from zinc with a synergistic mixture of nonylsalicylic acid and triisobutylphosphine sulphide

    , Article Hydrometallurgy ; Volume 78, Issue 1-2 SPEC. ISS , 2005 , Pages 129-136 ; 0304386X (ISSN) Moradkhani, D ; Urbani, M ; Cheng, C. Y ; Askari, M ; Bastani, D ; Sharif University of Technology
    2005
    Abstract
    Metal pH50 and ΔpH50 values were determined and compared for a number of organic systems to select a synergistic system for the separation of Cd from Zn. The largest ΔpH50(Zn-Cd) value was obtained with HRJ-4277 (nonylsalicylic acid)/Cyanex 471X (triisobutyl phosphine sulphide or TIBPS) system and reached 1.53 pH units, indicating excellent separation of Cd from Zn with this system. Shellsol 2046 was chosen as the diluent of the system due to its larger ΔpH50(Zn-Cd) and excellent phase separation compared with other diluents. Distribution isotherms and subsequent McCabe-Thiele diagrams indicate that 99% Cd could be extracted in two stages at pH 3.80 and A / O ratio of 1.5 : 1. The extraction... 

    Oxidation of aldehydes and ketones into carboxylic acids and esters using 4-amino-2-chloroperbenzoic acid supported on silica gel

    , Article Synthetic Communications ; Volume 35, Issue 8 , 2005 , Pages 1103-1107 ; 00397911 (ISSN) Hashemi, M. M ; Ghazanfari, D ; Ahmadibeni, Y ; Karimi Jaberi, Z ; Ezabadi, A ; Sharif University of Technology
    2005
    Abstract
    4-Amino-2-chloroperbenzoic acid supported on silica gel was found to be a versatile and efficient oxidant for the oxidation of aldehydes and ketones to the corresponding carboxylic acids and esters. Copyright © Taylor & Francis, Inc  

    Impact of sulfate ions on wettability alteration of oil-wet calcite in the absence and presence of cationic surfactant

    , Article Energy and Fuels ; Volume 30, Issue 2 , 2016 , Pages 819-829 ; 08870624 (ISSN) Karimi, M ; Al-Maamari, R. S ; Ayatollahi, S ; Mehranbod, N ; Sharif University of Technology
    American Chemical Society  2016
    Abstract
    The modification of the surface wetting characteristics in fractured oil-wet carbonate reservoirs, by reversing wettability from oil-wet to water-wet, leads to improved oil recovery. However, in order to obtain a successful oil recovery process, it is crucial to understand the active mechanisms of wettability alteration. This study looks at the effect of sulfate ions as one of the most promising wettability influencing ions on the wetting properties of oil-wet calcite; the effect is studied both with and without the presence of cationic surfactant and possible mechanisms of wettability alteration are explored. A number of analytical techniques were utilized to analyze the mineral surface... 

    Mesoporous silica nanoparticles with bilayer coating of poly(acrylic acid-co-itaconic acid) and human serum albumin (HSA): A pH-sensitive carrier for gemcitabine delivery

    , Article Materials Science and Engineering C ; Volume 61 , 2016 , Pages 782-790 ; 09284931 (ISSN) Pourjavadi, A ; Mazaheri Tehrani, Z ; Sharif University of Technology
    Abstract
    Novel bilayer coated mesoporous silica nanoparticle (MCM-41) based on pH sensitive poly(acrylic acid-co-itaconic acid) and human serum albumin (HSA) was designed for controlled delivery of gemcitabine (anticancer drug) to cancer cells. The shell around the mesoporous silica has bilayer structure. Poly(acrylic acid-co-itaconic acid) was used as pH-sensitive inner shell and human serum albumin, HSA, was used as outer shell. The core-shell structure was formed due to electrostatic interaction between ammonium groups of modified MCM-41 and carboxylate groups of copolymer. Also, the albumin layer was wrapped around the copolymer coated nanoparticle by electrostatic interaction between ammonium... 

    NMR investigation and theoretical calculations of the solvent effect on the conformation of valsartan

    , Article Journal of Molecular Structure ; Volume 1148 , 2017 , Pages 73-80 ; 00222860 (ISSN) Chashmniam, S ; Tafazzoli, M ; Sharif University of Technology
    Abstract
    Structure and conformational properties of valsartan were studied by advanced NMR techniques and quantum calculation methods. Potential energy scanning using B3LYP/6-311++g** and B3LYP-D3/6-311++g** methods were performed and four conformers (V1-V4) at minimum points of PES diagram were observed. According to the NMR spectra in acetone-d6, there are two conformers (M and m) with mM = 0.52 ratio simultaneously and energy barriers of the two conformers were predicted from chemical shifts and multiplicities. While, intramolecular hydrogen bond at tetrazole ring and carboxylic groups prevent the free rotation on N6[sbnd]C11 bond in M-conformer, this bond rotates freely in m-conformer. On the... 

    Ultrasensitive detection of cancer biomarkers using conducting polymer/electrochemically reduced graphene oxide-based biosensor: Application toward BRCA1 sensing

    , Article Sensors and Actuators, B: Chemical ; Volume 266 , 2018 , Pages 160-169 ; 09254005 (ISSN) Shahrokhian, S ; Salimian, R ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    Breast Cancer (BRCA) is the most common threat in women worldwide. Increasing death rate of diagnosed cases is the main leading cause of designing specific genosensors for BRCA − related cancer detection. In the present study, an ultrasensitive label − free electrochemical DNA (E − DNA) sensor based on conducting polymer/reduced graphene − oxide platform has been developed for the detection of BRCA1 gene. An electrochemical method was applied as a simple and controllable technique for the electrochemical reduction of graphene oxide and also, electro − polymerization of pyrrole − 3 − carboxylic acid monomer. The results of the present work show that the polymer − coated reduced graphene −... 

    Atomistic insight into the behavior of ions at an oil-bearing hydrated calcite surface: implication to ion-engineered waterflooding

    , Article Energy and Fuels ; Volume 35, Issue 16 , 2021 , Pages 13039-13054 ; 08870624 (ISSN) Badizad, M. H ; Koleini, M. M ; Greenwell, H. C ; Ayatollahi, S ; Ghazanfari, M. H ; Sharif University of Technology
    American Chemical Society  2021
    Abstract
    This research provides an atomistic picture of the role of ions in modulating the microstructural features of an oil-contaminated calcite surface. This is of crucial importance for the rational design of ion-engineered waterflooding, a promising technique for enhancing oil recovery from carbonate reservoirs. Inspired by a conventional lab-scale procedure, an integrated series of molecular dynamics (MD) simulations were carried out to resolve the relative contribution of the major ionic constituent of natural brines (i.e., Na+, Cl-, Mg2+, Ca2+, and SO42-) when soaking an oil-bearing calcite surface in different electrolyte solutions of same salinity, namely, CaCl2, MgCl2, Na2SO4, MgSO4, and... 

    Direct transesterification of wet microalgae to biodiesel using phosphonium carboxylate ionic liquid catalysts

    , Article Biomass and Bioenergy ; Volume 150 , 2021 ; 09619534 (ISSN) Malekghasemi, S ; Kariminia, H. R ; Plechkova, N. K ; Ward, V. C. A ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    In this study, four types of tetrabutylphosphonium carboxylate ionic liquids (ILs) were synthesized and used for a one-pot transesterification of wet Chlorella vulgaris (C. vulgaris) microalgae into fatty acid methyl esters (FAME) in the presence of methanol, as well as refined oils (sunflower, canola, and corn oil). The resulting process removed the need for complete drying and lipid extraction steps typically needed for biodiesel production from microalgae. The leading candidate ionic liquid catalyst, tetrabutylphosphonium formate ([P4444][For]), was further optimized using response surface methodology to minimize material consumption, increase water compatibility, reduce processing time... 

    DNA-decorated graphene nanomesh for detection of chemical vapors

    , Article Applied Physics Letters ; Volume 103, Issue 18 , 2013 ; 00036951 (ISSN) Esfandiar, A ; Kybert, N. J ; Dattoli, E. N ; Hee Han, G ; Lerner, M. B ; Akhavan, O ; Irajizad, A ; Charlie Johnson, A. T ; Sharif University of Technology
    2013
    Abstract
    The promise of graphene for use as a vapor sensor motivated exploration of the vapor responses of graphene nanomesh (GNM) functionalized with single stranded DNA. Devices detected different vapor types, including carboxylic acids, aldehydes, organophosphates, and explosives. As-fabricated GNM field effect transistors (FETs) had larger vapor responses than standard graphene FETs due to the effect of oxidized edges and lattice defects. DNA-GNM devices discriminated between homologous species with detection limits of a few parts per million, with fast response and recovery. Responses varied significantly when the base sequence of the DNA was changed, making the sensor class an intriguing... 

    Cure kinetic and network structure of NR/SBR composites reinforced by multiwalled carbon nanotube and carbon blacks

    , Article Thermochimica Acta ; Volume 566 , 2013 , Pages 238-248 ; 00406031 (ISSN) Ahmadi, M ; Shojaei, A ; Sharif University of Technology
    2013
    Abstract
    Low structure carbon black (CBN330), conductive high structure carbon black (CBXE2B) and carboxylated multiwalled carbon nanotube (MWCNT) were loaded into the blend of natural rubber (NR) and styrene butadiene rubber (SBR) at different contents up to 10 phr. Kraus plots showed that all the reinforcements interact with NR/SBR blend appropriately. However, the CBXE2B whose interfacial area is the highest showed greatest value of Kraus interaction parameter. Flory-Rhener model and effective torque value revealed that all of the reinforcements enhanced the crosslink density, among them CBXE2B showed the highest impact and MWCNT placed in the second rank. It was also shown that the cure kinetic... 

    Dendritic magnetite decorated by pH-responsive PEGylated starch: A smart multifunctional nanocarrier for the triggered release of anti-cancer drugs

    , Article RSC Advances ; Volume 5, Issue 60 , Jun , 2015 , Pages 48586-48595 ; 20462069 (ISSN) Pourjavadi, A ; Mazaheri Tehrani, Z ; Hosseini, S. H ; Sharif University of Technology
    Royal Society of Chemistry  2015
    Abstract
    In the present study, we designed a pH-responsive drug nanocarrier based on polyamidoamine-modified Fe3O4 nanoparticles coated by PEGylated starch-co-poly(acrylic acid). This carrier was used for the controlled release of doxorubicin as an anticancer drug model. The purpose of using the polyethylene glycol moiety is to generate a biostable nanocarrier in blood stream as it has been reported widely in the pharmaceutical literature. The use of a poly(acrylic acid) segment also provided pH-sensitivity to the polymer. Besides, the magnetic nanoparticles facilitate the cancer cell targeting with an external magnetic field located near the tumor site. This carrier was... 

    Synthesis, characterizations and catalytic studies of a new two-dimensional metal-organic framework based on Co-carboxylate secondary building units

    , Article Journal of Solid State Chemistry ; Volume 223 , March , 2015 , Pages 32-37 ; 00224596 (ISSN) Bagherzadeh, M ; Ashouri, F ; Daković, M ; Sharif University of Technology
    Academic Press Inc  2015
    Abstract
    A metal-organic framework [Co3(BDC)3(DMF)2(H2O)2] was synthesized and structurally characterized. X-ray single crystal analysis revealed that the framework contains a 2D polymeric chain through coordination of 1,4-benzenedicarboxylic acid linker ligand to cobalt centers. The polymer crystallize in monoclinic P21/n space group with a=13.989(3) Å, b=9.6728(17) Å, c=16.707(3) Å, and Z=2. The polymer features a framework based on the perfect octahedral Co-O6 secondary building units. The catalytic activities of [Co3(BDC)3(DMF)2(H2O)2]n for olefins oxidation was conducted. The heterogeneous catalyst could be facilely separated from the reaction mixture, and reused three times without significant...