Search for: organic-acids
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    Chemometrical modeling of electrophoretic mobilities in capillary electrophoresis

    , Article Chemometric Methods in Capillary Electrophoresis ; 2009 , Pages 323-343 ; 9780470393291 (ISBN) Jalali Heravi, M ; Sharif University of Technology
    John Wiley & Sons, Inc  2009

    Conversion of a weak organic acid to a super acid in the gas phase

    , Article Journal of Physical Organic Chemistry ; Volume 21, Issue 2 , 2008 , Pages 112-118 ; 08943230 (ISSN) Fattahi, A ; Tavasoli, E ; Sharif University of Technology
    The effects of selected metal ions on the gas-phase acidity of weak organic acids have been explored using the DFT and Moller-Plesset Perturbation Theory (MP2) calculations. The three organic acids selected for this study were acetic acid (aliphatic), benzoic acid (aromatic), and glycine (amino acid). The acidities of these compounds are compared with the acidity of their Li +-, Na+-, and K+ -complexed species. The results indicate that upon complexation with Li+, Na+, and K+ at 298K, the gas-phase acidity of acetic acid, for example, varies from 345.3 to 218.8, 230.2, and 240.1 kcal/mol, respectively (i.e., its dissociation becomes much less endothermic). These values indicate that a weak... 

    The first report on the catalytic oxidation of urazoles to their corresponding triazolinediones via in situ catalytic generation of Br+ using periodic acid or oxone®/KBr system

    , Article Journal of Molecular Catalysis A: Chemical ; Volume 270, Issue 1-2 , 2007 , Pages 219-224 ; 13811169 (ISSN) Zolfigol, M. A ; Bagherzadeh, M ; Mallakpour, S ; Chehardoli, G ; Ghorbani Choghamarani, A ; Koukabi, N ; Dehghanian, M ; Doroudgar, M ; Sharif University of Technology
    A combination of periodic acid or oxone® and a catalytic amount of KBr in the presence of few drops of water, were used for the catalytic oxidation of urazoles and bis-urazoles to their corresponding triazolinediones under mild and heterogeneous conditions with moderate to excellent yields. © 2007 Elsevier B.V. All rights reserved  

    Protein- and homo poly(amino acid)-based hydrogels with super-swelling properties

    , Article Polymers for Advanced Technologies ; Volume 20, Issue 8 , 2009 , Pages 655-671 ; 10427147 (ISSN) Zohuriaan Mehr, M. J ; Pourjavadi, A ; Salimi, H ; Kurdtabar, M ; Sharif University of Technology
    The use of super-swelling polymers is steadily increasing and the applications in industry are continuing to grow. With the authorization of the superabsorbents in food packaging by the Food and Drug Administration recently, demand may soon take off in the market. However, the increase in prices of petroleum products in recent years may be a drawback for these acrylic-based materials. Thus, there is now a need to develop natural-based super-swelling hydrogels which are more economical and environment friendly. In addition, the super-swelling gels are promising novel functions in the biomedical and pharmaceutical applications. This review is aimed to highlight research and trends in protein-... 

    Optimization of synthesis conditions of a novel carrageenan-based superabsorbent hydrogel by taguchi method and investigation of its metal ions adsorption

    , Article Journal of Applied Polymer Science ; Volume 107, Issue 5 , 2008 , Pages 2970-2976 ; 00218995 (ISSN) Pourjavadi, A ; Amini Fazl, M. S ; Barzegar, Sh ; Sharif University of Technology
    The Taguchi method, a robust experimental design, was used for optimization of synthesis of a novel biopolymer-based superabsorbent hydrogel, kappa-carrageenan (K-C)-g-acrylic acid (AA)-co-2-acrylamido-2- methylpropanesulfonic acid (AMPS). The Taguchi method was applied for the experimental and standard 18 orthogonal arrays (OA) with seven factors and three levels for each factor. In the synthesis of the superabsorbent, N,N'-methylene bisacrylamide (MBA) as crosslinker, ammonium persulfate (APS) as initiator, monomer ratio (AA/AMPS), K-C concentration, Total Monomer, neutralization percent (NU), and reaction temperature were used as important factors. After analyzing with analysis of... 

    Simultaneous voltammetric detection of ascorbic acid and uric acid at a carbon-paste modified electrode incorporating thionine-nafion ion-pair as an electron mediator

    , Article Electrochimica Acta ; Volume 51, Issue 13 , 2006 , Pages 2599-2606 ; 00134686 (ISSN) Shahrokhian, S ; Ghalkhani, M ; Sharif University of Technology
    The electrochemical behavior of ascorbic acid (AA) and uric acid (UA) at the surface of a carbon-paste electrode modified with incorporate thionine-nafion ion-paired was thoroughly investigated. The results show the presence of nafion inside the matrix of modified electrode, because of the effective ion-pairing and hydrophobic interactions, significantly enhances the stability of thionine as an electron mediator inside the modified electrode. A high reproducibility in voltammetric response to analyte species results because of this enhancement. The cyclic voltammetric studies using the prepared modified electrode show the best electrocatalytic property for the electro-oxidation of AA and... 

    The selective aerobic oxidation of methylaromatics to benzaldehydes using a unique combination of two heterogeneous catalysts

    , Article Organic and Biomolecular Chemistry ; Volume 3, Issue 5 , 2005 , Pages 725-726 ; 14770520 (ISSN) Rajabi, F ; Clark, J. H ; Karimi, B ; Macquarrie, D. J ; Sharif University of Technology
    A unique combination of a supported cobalt complex and the first example of supported NHPI in acetic acid gives a surprisingly stable heterogeneous catalytic system for the selective aerobic oxidation of methylaromatics to benzaldehydes at atmospheric pressure. © The Royal Society of Chemistry 2005  

    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
    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 of Conductive Magnetite Nanocomposite based on Polyaniline/Poly(maleic acid-co-acrylic acid) with Core-Shell Structure

    , Article Advances in Polymer Technology ; 2016 ; 07306679 (ISSN) Khodadadi, F ; Najafi Moghadam, P ; Mahmoodi Hashemi, M ; Sharif University of Technology
    John Wiley and Sons Inc  2016
    In this study, a new type of magnetite nanocomposite with a core-shell structure was synthesized using Fe3O4 nanoparticles as a core and polyaniline (PANI) as a shell. For this propose, the surface of Fe3O4 was chemically modified with hexamethylenediisocyanate (HMDI) to improve its compatibility and interphase interaction with the polymeric matrix. Thereafter, the PANI was reacted with modified Fe3O4 to anchor them to PANI by covalent bands which acted as a shell. In the second step, the poly (maleic acid-co-acrylic acid) (P(MAc-co-AA)) as polymeric dopant for the PANI was synthesized. Finally, the PANI anchored to Fe3O4 was immersed in an aqueous solution of poly (maleic... 

    Liquid-Liquid equilibrium data, density, viscosity, and interfacial tension of ternary system (Toluene-Acetic Acid-Water) at 298.15 K: Experiment and correlation

    , Article Journal of Chemical and Engineering Data ; Volume 62, Issue 12 , 2017 , Pages 4133-4143 ; 00219568 (ISSN) Memari, M ; Molaei Dehkordi, A ; Seifkordi, A. A ; Sharif University of Technology
    Liquid-liquid equilibrium (LLE) data, density, viscosity, and interfacial tension for the ternary system of toluene-acetic acid-water were measured at 298.15 K and 101.7 kPa. The Othmer-Tobias and the Hand correlations were used to check the reliability of the experimental tie-lines. Moreover, the distribution coefficient and the separation factor were explored. It was found from the experimental results that a maximum separation factor value happens at an acetic acid mass fraction of 0.02 in the organic phase. Density, viscosity, and interfacial tension were correlated using the appropriate correlations such that the predicted results have excellent agreement with the experimental data. The... 

    Removal of humic acid from aqueous solution using photocatalytic reaction on perlite granules covered by nano TiO2 particles

    , Article Journal of Molecular Liquids ; Volume 242 , 2017 , Pages 357-363 ; 01677322 (ISSN) Joolaei, H ; Vossoughi, M ; Rashidi Mehr Abadi, A ; Heravi, A ; Sharif University of Technology
    Humic acid (HA) constitutes a large portion of natural organic matter (NOM), and is the main precursor of toxic and cancerogenic Trihalomethanes compounds, formed during chlorination of drinking water. Therefore, it is essential that the humic acid be eliminated from water before treating it. The present study aims to investigate the photocatalytic degradation of humic acid (HA) using TiO2 nanoparticles immobilized on perlite granules (TIP), irradiated by UV light in a photoreactor. Samples of coated perlites were prepared by a dip coating method using a commercial powder of TiO2. Characteristics of the prepared samples were evaluated by X-ray and scanning electron microscope techniques.... 

    Synthesis and characterization of polyamide membrane for the separation of acetic acid from water using RO process

    , Article Membrane Water Treatment ; Volume 8, Issue 4 , 2017 , Pages 323-336 ; 20058624 (ISSN) Mirfarah, H ; Mousavi, S. A ; Mortazavi, S. S ; Sadeghi, M ; Bastani, D ; Sharif University of Technology
    Techno Press  2017
    The main challenge in many applications of acetic acid is acid dehydration and its recovery from wastewater streams. Therefore, the performance of polyamide thin film composite is evaluated to separate acetic acid from water. To reach this goal, the formation of polyamide layer on polysulfone support membrane was investigated via interfacial polymerization (IP) of meta-phenylenediamine (MPD) in water with trimesoyl chloride (TMC) in hexane. Also, the effect of synthesis conditions, such as concentration of monomers and curing temperature on separation of acetic acid from water were investigated by reverse osmosis process. Moreover, the separation mechanism was discussed. The solute... 

    Simple and rapid detection of L-dopa based on in situ formation of polylevodopa nanoparticles

    , Article Sensors and Actuators, B: Chemical ; Volume 243 , 2017 , Pages 715-720 ; 09254005 (ISSN) Hormozi Nezhad, M. R ; Moslehipour, A ; Bigdeli, A ; Sharif University of Technology
    Elsevier B.V  2017
    Levodopa [L-3, 4-dihydroxyphenylalanine, or L-DOPA] is an important neurotransmitter used for the treatment of neural disorders such as Parkinson's disease. Abnormal L-Dopa concentrations in biological fluids can be used for the evaluation of such diseases. In this work, a rapid and sensitive method for L-DOPA detection has been reported which is based on in situ formation of polylevodopa nanoparticles. Under alkaline conditions, L-DOPA is spontaneously oxidized to its quinone derivative and shows fluorescence properties. The fluorescence signal of the oxidation product has been monitored and used for the determination of L-DOPA in the presence of dopamine, uric acid, ascorbic acid and other... 

    New organic dyes with diphenylamine core for dye-sensitized solar cells

    , Article Journal of Materials Science: Materials in Electronics ; Volume 29, Issue 8 , April , 2018 , Pages 6323-6336 ; 09574522 (ISSN) Salimi Beni, A. R ; Karami, M ; Hosseinzadeh, B ; Ghahary, R ; Sharif University of Technology
    Springer New York LLC  2018
    In the current investigation, four novel donoracceptor type organic dyes including (DPA-Ba, DPA-Hy, DPA-Rh, DPA-Cy), are proposed and their photophysical and electrochemical properties as well as dye-sensitized solar cell performance are systematically investigated. Among these dyes diphenylamine is utilized as an-electron donor while barbituric acid, hydantoin, rhodanine-n-acetic acid and cyano acetic acid, are proposed as anchoring groups as dye-sensitized solar cells (DSSCs). The synthesized dyes are characterized using FT-IR, NMR, mass spectrometry, absorbance and electrochemical measurements. The photophysical, electrochemical and photovoltaic properties of the solar cells based on... 

    Smart pectin-based superabsorbent hydrogel as a matrix for ibuprofen as an oral non-steroidal antiinflammatory drug delivery

    , Article Starch/Staerke ; Volume 61, Issue 3-4 , 2009 , Pages 173-187 ; 00389056 (ISSN) Pourjavadi, A ; Barzegar, S ; Sharif University of Technology
    The purpose of this study was to produce an intelligent superabsorbent polymer (SAP) to be used as a pH sensitive matrix for the controlled delivery of drugs. Novel types of highly swelling SAPs were prepared by grafting crosslinked acrylic acid-co-acrylamide (AA-co-AAm) chains onto pectin by free-radical polymerization. The superabsorbent formation was confirmed by Fourier transform infrared spectroscopic (FT-IR) and scanning electron microscopy (SEM). The controlled release behavior of ibuprofen (IBU) from the superabsorbent polymer was investigated. SAP structural-property relationships that affect its controlled release behavior were determined. Analysis of the results indicated that it... 

    Synthesis and evaluation of pH and thermosensitive pectin-based superabsorbent hydrogel for oral drug delivery systems

    , Article Starch/Staerke ; Volume 61, Issue 3-4 , 2009 , Pages 161-172 ; 00389056 (ISSN) Pourjavadi, A ; Barzegar, S ; Sharif University of Technology
    The purpose of this study was to produce intelligent pectin-based superabsorbent polymers (SAP) to be used as pH- and thermosensitive carriers for the controlled delivery of non-steroidal anti-inflammatory drugs (NSAIDs). The superabsorbent formation was confirmed by Fourier transform infrared spectroscopic (FT-IR) and scanning electron microscopy (SEM). The effects of pH, ionic strength, temperature, porosity, particle size and levels of loaded drug on drug release profile in various surrounding media were investigated. Each sample was well characterized through swelling studies. The molecular weight between crosslinks (M̄C), crosslinking density (ve) polymer-solvent interaction parameter... 

    Synthesis and investigation of swelling behavior of new agar based superabsorbent hydrogel as a candidate for agrochemical delivery

    , Article Journal of Polymer Research ; Volume 16, Issue 6 , 2009 , Pages 655-665 ; 10229760 (ISSN) Pourjavadi, A ; Farhadpour, B ; Seidi, F ; Sharif University of Technology
    In this investigation a new type of superabsorbent hydrogel based on agar was prepared, and the effect of the feed ratio of some components (acrylic acid, MBA, APS and agar) on the swelling capacity of the hydrogel was systematically studied. Maximum water absorbency of the optimized final product was found to be 1,100∈g/g in distilled water. The structure of the hydrogel was characterized by FT-IR method and morphology of the samples was examined by scanning electron microscopy (SEM). Swelling properties of optimized hydrogel sample in different swelling mediums were investigated. The optimum hydrogel were also loaded with potassium nitrate and its potential for controlled release of... 

    Enzymatically crosslinked hyaluronic acid microgels as a vehicle for sustained delivery of cationic proteins

    , Article European Polymer Journal ; Volume 115 , 2019 , Pages 234-243 ; 00143057 (ISSN) Jooybar, E ; Abdekhodaie, M. J ; Mousavi, A ; Zoetebier, B ; Dijkstra, P. J ; Sharif University of Technology
    Elsevier Ltd  2019
    In this study, a novel biodegradable hyaluronic acid (HA) based microgel were prepared via enzymatic crosslinking of tyramine conjugated HA (HA-TA) in an inverse microemulsion. HA-TA microdroplets were crosslinked within a few seconds in the presence of horseradish peroxidase (HRP) and hydrogen peroxide (H 2 O 2 ). The high water content of the polymeric network and the inherent negative charge of the HA-TA microgels provided a suitable platform for encapsulation of cationic proteins like lysozyme and TGF-β1 growth factor. The results demonstrated that lysozyme was released, after an initial burst release, in a suitable sustained manner over a period of four weeks. Both diffusion and... 

    Potential effects of alginate–pectin biocomposite on the release of folic acid and their physicochemical characteristics

    , Article Journal of Food Science and Technology ; Volume 57, Issue 9 , March , 2020 , Pages 3363-3370 Kiaei Pour, P ; Alemzadeh, I ; Vaziri, A. S ; Beiroti, A ; Sharif University of Technology
    Springer  2020
    Potential effects of folates on the treatment of several human diseases like cognitive function, neural tube defects, coronary heart disease and certain kinds of cancers have been discovered. However, the stability of folic acid against adverse conditions is a great concern. The present study investigates various alginate (A)–pectin (P) gastrointestinal-resistant hydrogel to immobilize folic acid. This involves evaluating different compositions of alginate–pectin to achieve higher encapsulation efficiency and stability during simulated gastric (SG) and simulated intestinal (SI) conditions. Coated alginate hydrogels with pectin resulted significant (p < 0.05) better protection of folic acid... 

    Facile design of autogenous stimuli-responsive chitosan/hyaluronic acid nanoparticles for efficient small molecules to protein delivery

    , Article Journal of Materials Chemistry B ; Volume 8, Issue 32 , 2020 , Pages 7275-7287 Sabourian, P ; Ji, J ; Lotocki, V ; Moquin, A ; Hanna, R ; Frounchi, M ; Maysinger, D ; Kakkar, A ; Sharif University of Technology
    Royal Society of Chemistry  2020
    Easily assembled and biocompatible chitosan/hyaluronic acid nanoparticles with multiple stimuli-responsive ability are ideally suited for efficient delivery of therapeutic agents under specific endogenous triggers. We report a simple and versatile strategy to formulate oxidative stress and pH-responsive chitosan/hyaluronic acid nanocarriers with high encapsulation efficiencies of small drug molecules and nerve growth factor protein. This is achieved through invoking the dual role of a thioketal-based weak organic acid to disperse and functionalize low molecular weight chitosan in one-pot. Thioketal embedded chitosan/hyaluronic acid nanostructures respond to oxidative stress and show...