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Total 45 records

    Modification of carbohydrate polymers via grafting in Air. 2. Ceric-Initiated graft copolymerization of acrylonitrile onto natural and modified polysaccharides [electronic resource]

    , Article Starch - Stärke ; Volume 54, Issue 10, pages 482–488, October 2002 Pourjavad, A. (Ali) ; Zohuriaan-Mehr, Mohammad J
    Abstract
    Acrylonitrile (AN) was grafted onto various natural and modified polysaccharides (i.e., gum arabic, gum tragacanth, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) by using ceric-carbohydrate redox initiating system. After overcoming practical problems, mainly from the high viscosity of the aqueous solutions of the different substrates, the graft copolymerization reactions were run either in air or in N2 atmosphere under similar conditions. Grafting was confirmed using chemical and spectral (FTIR) proofs. The reactions were kinetically investigated using semi-empirical expressions and time-temperature profiles. An anomalous... 

    Modified Chitosan. 2. H-chitoPAN, a novel pH-responsive superabsorbent hydrogel [electronic resource]

    , Article Journal of Applied Polymer Science ; Volume 90, Issue 11, pages 3115–3121, 9 December 2003 Pourjavadi, A. (Ali) ; Mahdavinia, G. R ; Zohuriaan-Mehr, M. J
    Abstract
    Chitosan was modified with polyacrylonitrile (PAN) through ceric-initiated graft copolymerization. The chitosan-g-PAN product was saponified using sodium hydroxide aqueous solution to prepare a novel superabsorbent hydrogel, H-chitoPAN. Duration of completing the saponification reaction as well as the water absorbency capacity of the hydrogel was decreased with increasing the alkaline concentration. Either chitosan-g-PAN or H-chitoPAN was characterized by FTIR spectroscopy and DSC, TGA, and DTG thermal methods. According to FTIR, all the nitrile groups were converted to carboxylate and carboxamide groups. Both modified chitosans exhibited enhanced thermal stability over chitosan. The... 

    Modified CMC: part 1- optimized synthesis of carboxymethylcellulose-g-polyacrylonitrile [electronic resource]

    , Article Iranian Polymer Journal ; Vol. 14, No 2, 131-138, 2005 Zohurian Mehr, M. J. (Mohammad Jalal) ; Pourjavadi, A ; Sadeghi, M
    Abstract
    As the first part of a continued research on conversion of carboxymethyl cellulosesodium salt (CMC) to useful biopolymer-based materials, large numbers of cyanide functional groups were introduced onto CMC by grafting with polyacrylonitrile (PAN). The graft copolymerization reactions were carried out under nitrogen atmosphere using ceric ammonium nitrate (CAN) as an initiator. Evidence of grafting was obtained by comparing FTIR spectra of CMC and the graft copolymer as well as solubility characteristics of the products. The synthetic conditions were systematically optimized through studying the effective factors including temperature and concentrations of initiator, acrylonitrile monomer,... 

    Nanodiamonds for surface engineering of orthopedic implants: Enhanced biocompatibility in human osteosarcoma cell culture [electronic resource]

    , Article Diamond and Related Materials ; Volume 40, 2013, Pages 107-114 Mansoorianfar, M. (Mojtaba) ; Shokrgozar, M. A ; Mehrjoo, M ; Tamjid, E ; Simchi, A ; Sharif University of Technology
    Abstract
    Recently, nanodiamonds have attracted interest in biomedical applications such as drug delivery, targeted cancer therapies, fabrication of tissue scaffolds, and biosensors. We incorporated diamond nanoparticles in alginate–bioactive glass films by electrophoretic process to prepare functional coatings for biomedical implants. Turbidity examination by time-resolved laser transmittance measurement revealed that a stable multi-component aqueous suspension of alginate, bioactive glass and diamond particles could be obtained at concentrations of 0.6, 1.3, and 0.65 g/l, respectively. Uniform films with ~ 5 μm thickness were deposited on 316 stainless steel foils by employing constant field... 

    Synthesis of soluble N-functionalized polysaccharide derivatives using phenyl carbonate precursor and their application as catalysts

    , Article Starch/Staerke ; Volume 63, Issue 12 , 2011 , Pages 780-791 ; 00389056 (ISSN) Pourjavadi, A ; Seidi, F ; Afjeh, S. S ; Nikoseresht, N ; Salimi, H ; Nemati, N ; Sharif University of Technology
    2011
    Abstract
    Soluble N-functionalized basic and cationic polysaccharides have been synthesized using polysaccharide phenyl carbonate as a precursor. The products and intermediates were thoroughly characterized by conventional methods. The quaternization of amino intermediates in various conditions was studied. Moreover, the potential of basic polymers as green and selective catalysts in Knoevenagel reaction was investigated. In all cases, only one isomer was obtained  

    Modified chitosan. II. H-chitoPAN, a novel pH-responsive superabsorbent hydrogel

    , Article Journal of Applied Polymer Science ; Volume 90, Issue 11 , 2003 , Pages 3115- ; 00218995 (ISSN) Pourjavadi, A ; Mahdavinia, G. R ; Zohuriaan Mehr, M. J ; Sharif University of Technology
    2003
    Abstract
    Chitosan was modified with polyacrylonitrile (PAN) through ceric-initiated graft copolymerization. The chitosan-g-PAN product was saponified using sodium hydroxide aqueous solution to prepare a novel superabsorbent hydrogel, H-chitoPAN. Duration of completing the saponification reaction as well as the water absorbency capacity of the hydrogel was decreased with increasing the alkaline concentration. Either chitosan-g-PAN or H-chitoPAN was characterized by FTIR spectroscopy and DSC, TGA, and DTG thermal methods. According to FTIR, all the nitrile groups were converted to carboxylate and carboxamide groups. Both modified chitosans exhibited enhanced thermal stability over chitosan. The... 

    Modification of carbohydrate polymers via grafting in air: 2. Ceric-initiated graft copolymerization of acrylonitrile onto natural and modified polysaccharides

    , Article Starch/Staerke ; Volume 54, Issue 10 , 2002 , Pages 482-488 ; 00389056 (ISSN) Pourjavadi, A ; Zohuriaan Mehr, M. J ; Sharif University of Technology
    2002
    Abstract
    Acrylonitrile (AN) was grafted onto various natural and modified polysaccharides (i.e., gum arabic, gum tragacanth, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) by using ceric-carbohydrate redox initiating system. After overcoming practical problems, mainly from the high viscosity of the aqueous solutions of the different substrates, the graft copolymerization reactions were run either in air or in N2 atmosphere under similar conditions. Grafting was confirmed using chemical and spectral (FTIR) proofs. The reactions were kinetically investigated using semi-empirical expressions and time-temperature profiles. An anomalous... 

    New polysaccharide-g-polyacrylonitrile copolymers: synthesis and thermal characterization [electronic resource]

    , Article Polymers for Advanced Technologies ; Volume 14, Issue 7, pages 508–516, July 2003 Zohurian Mehr, M. J. (Mohammad Jalal) ; Pourjavadi, Ali ; Sharif University of Technology
    Abstract
    Various natural and modified polysaccharides (i.e. arabic gum, tragacanth gum, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) were modified using ceric-initiated graft polymerization of acrylonitrile under inert atmosphere. Grafting was confirmed using spectral (FT-IR) proofs. The grafting parameters were determined by conventional methods. Thermal characteristics of the homopolymer-free copolymers were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) under nitrogen atmosphere. The major thermal transitions as well as the activation energy of the major decomposition stages were... 

    Modified CMC.2. Novel carboxymethylcellulose-based poly (amidoxime) chelating resin with high metal sorbtion capacities [electronic resource]

    , Article Reactive and Functional Polymers ; Volume 61, Issue 1, August 2004, Pages 23–31 Zohurian Mehr, M. J. (Mohammad Jalal) ; Pourjavadi, A ; Sadeghi, M ; Sharif University of Technology
    Abstract
    Carboxymethylcellulose sodium salt (CMC) was doubly modified to prepare a novel poly(acrylamidoxime) chelating resin. Acrylonitrile was firstly graft polymerized onto CMC using cerium ammonium nitrate as an initiator. The polyacrylonitrile (PAN) grafted CMC was then amidoximized via treatment with hydroxylamine to prepare the ion exchange resin. The sorption capacity of the resin towards bivalent metal ions was evaluated while varying the pH, the loading of the PAN and the initial metal ion concentration. The adsorption kinetics were investigated for the cupric ion. The chelating resin exhibited very high metal sorption capacity in comparison with either synthetic or polysaccharide-based... 

    Modified CMC. 2. Novel carboxymethylcellulose-based poly(amidoxime) chelating resin with high metal sorption capacity

    , Article Reactive and Functional Polymers ; Volume 61, Issue 1 , 2004 , Pages 23-31 ; 13815148 (ISSN) Zohuriaan Mehr, M. J ; Pourjavadi, A ; Salehi Rad, M ; Sharif University of Technology
    2004
    Abstract
    Carboxymethylcellulose sodium salt (CMC) was doubly modified to prepare a novel poly(acrylamidoxime) chelating resin. Acrylonitrile was firstly graft polymerized onto CMC using cerium ammonium nitrate as an initiator. The polyacrylonitrile (PAN) grafted CMC was then amidoximized via treatment with hydroxylamine to prepare the ion exchange resin. The sorption capacity of the resin towards bivalent metal ions was evaluated while varying the pH, the loading of the PAN and the initial metal ion concentration. The adsorption kinetics were investigated for the cupric ion. The chelating resin exhibited very high metal sorption capacity in comparison with either synthetic or polysaccharide-based... 

    Investigation of intestinal enzyme activity and effects of non-starch polysaccharide on it

    , Article International Journal of Engineering and Technology(UAE) ; Volume 7, Issue 4 , 2018 , Pages 28-31 ; 2227524X (ISSN) Piryaei, M ; Motamedi, A ; Mehrabi Far, A ; Sharif University of Technology
    Science Publishing Corporation Inc  2018
    Abstract
    This experiment investigates the effects of utilizing Rahnama cultivar with high non-starchy polysaccharide content and supplementation of xylanase enzyme in poultry feed on the productivity features, nutrient digestibility and intestinal enzymes activity of 21-47 week laying hens. The experiment was conducted quite randomly and in factorial design that included eight treatments with 4 wheat levels (zero, 23, 46 and 69% that contained 1.8, 2.0, 2.2, 2.4% of xylose respectively) and two level enzymes (with and without enzyme) and 5 replications (6 hens) in each replication. During the experiment, by xylose level increase in diet, the weight (p > 0.05) and mass of the egg (p > 0.01) decreased... 

    Modified CMC. 3. Carboxymethylcellulose-g-poly(acrylamidrazone) as a new metal adsorbent

    , Article Journal of Polymer Materials ; Volume 21, Issue 3 , 2004 , Pages 315-320 ; 09738622 (ISSN) Zohuriaan Mehr, M. J ; Pourjavadi, A ; Salehi Rad, M ; Sharif University of Technology
    2004
    Abstract
    A new poly(acrylamidrazone) chelating resin was prepared from carboxymethylcellulose (CMC) via a two-step process. First, acrylonitrile was graft polymerized onto the substrate. The CMC-polyacrylonitrile graft copolymer was then treated with hydrazine to yield a triply modified cellulose containing amidrazone functional groups. The resin was characterized using infrared spectroscopy. The sorption capacity of the resin towards bivalent metal ions was evaluated versus variation of pH and hydrochloric acid concentration. The adsorption capacities at pH 6 were found to be in order Cu2+> Zn2+>Cd2+>Co2+>Ni2+. The metal ion sorption capacities were varied in the range of 2.0-20.0 mmol metal per... 

    New polysaccharide-g-polyacrylonitrile copolymers: Synthesis and thermal characterization

    , Article Polymers for Advanced Technologies ; Volume 14, Issue 7 , 2003 , Pages 508-516 ; 10427147 (ISSN) Zohuriaan Mehr, M. J ; Pourjavadi, A ; Sharif University of Technology
    2003
    Abstract
    Various natural and modified polysaccharides (i.e. arabic gum, tragacanth gum, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) were modified using cericinitiated graft polymerization of acrylonitrile under inert atmosphere. Grafting was confirmed using spectral (FT-IR) proofs. The grafting parameters were determined by conventional methods. Thermal characteristics of the homopolymer-free copolymers were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) under nitrogen atmosphere. The major thermal transitions as well as the activation energy of the major decomposition stages were... 

    MBA-crosslinked Na-Alg/CMC as a smart full-polysaccharide superabsorbent hydrogels

    , Article Carbohydrate Polymers ; Volume 66, Issue 3 , 2006 , Pages 386-395 ; 01448617 (ISSN) Pourjavadi, A ; Barzegar, Sh ; Mahdavinia, G. R ; Sharif University of Technology
    2006
    Abstract
    A novel superabsorbent hydrogel composed of carboxymethylcellulose (CMC) and sodium alginate (Na-Alg) was prepared by using methylenebisacrylamide (MBA) as a crosslinking agent. Ammonium persulfate (APS) was used as an initiator. For investigation of the effect of reaction variables on water absorbency of the hydrogels, the synthetic conditions were systematically optimized through studying the influential factors, including temperature, Na-Alg/CMC weight ratio and concentration of MBA and APS. Increase in MBA and APS concentration results in the decrease in water absorbency of the hydrogels. The water absorbency of the hydrogels increased with increasing of reaction temperature and... 

    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
    2009
    Abstract
    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-... 

    Structure and conformation of α-, β- and γ-cyclodextrin in solution: theoretical approaches and experimental validation

    , Article Carbohydrate Polymers ; Volume 78, Issue 1 , 2009 , Pages 10-15 ; 01448617 (ISSN) Tafazzoli, M ; Ghiasi, M ; Sharif University of Technology
    2009
    Abstract
    The anomeric carbon chemical shifts of α-, β- and γ-cyclodextrin in solution were studied experimentally and theoretically by NMR and two-layer ONIOM2 (B3LYP/6-31G*-GIAO: HF/6-31G*-GIAO) variant. The dependence between the anomeric carbon chemical shift and the glycosidic bond φ and ψ dihedral angles in d-Glcp-d-Glcp disaccharides with and (1 → 4) linkages in α-configurations were computed by Gauge-Including Atomic Orbital (GIAO) ab initio and ONIOM in water solvent using PCM methods. Complete chemical shift surfaces versus φ and ψ for this disaccharide were computed. We also present empirical formulas of the form 13C δ = f(φ, ψ) obtained by fitting the ab initio data to trigonometric series... 

    Modified CMC: Part1-optimized synthesis of carboxymethyl cellulose-g-polyacrylonitrile

    , Article Iranian Polymer Journal (English Edition) ; Volume 14, Issue 2 , 2005 , Pages 131-138 ; 10261265 (ISSN) Zohuriaan Mehr, M. J ; Pourjavadi, A ; Sadeghi, M ; Sharif University of Technology
    2005
    Abstract
    As the first part of a continued research on conversion of carboxymethyl cellulose-sodium salt (CMC) to useful biopolymer-based materials, large numbers of cyanide functional groups were introduced onto CMC by grafting with polyacrylonitrile (PAN). The graft copolymerization reactions were carried out under nitrogen atmosphere using ceric ammonium nitrate (CAN) as an initiator. Evidence of grafting was obtained by comparing FTIR spectra of CMC and the graft copolymer as well as solubility characteristics of the products. The synthetic conditions were systematically optimized through studying the effective factors including temperature and concentrations of initiator, acrylonitrile monomer,... 

    Nanodiamonds for surface engineering of orthopedic implants: Enhanced biocompatibility in human osteosarcoma cell culture

    , Article Diamond and Related Materials ; Volume: 40 , 2013 , Pages: 107-114 ; 09259635 (ISSN) Mansoorianfar, M ; Shokrgozar, M. A ; Mehrjoo, M ; Tamjid, E ; Simchi, A ; Sharif University of Technology
    2013
    Abstract
    Recently, nanodiamonds have attracted interest in biomedical applications such as drug delivery, targeted cancer therapies, fabrication of tissue scaffolds, and biosensors. We incorporated diamond nanoparticles in alginate-bioactive glass films by electrophoretic process to prepare functional coatings for biomedical implants. Turbidity examination by time-resolved laser transmittance measurement revealed that a stable multi-component aqueous suspension of alginate, bioactive glass and diamond particles could be obtained at concentrations of 0.6, 1.3, and 0.65 g/l, respectively. Uniform films with ~ 5 μm thickness were deposited on 316 stainless steel foils by employing constant field... 

    Preparation and characterization of starch-based composite films reinforced by cellulose nanofibers

    , Article International Journal of Biological Macromolecules ; Volume 116 , 2018 , Pages 272-280 ; 01418130 (ISSN) Fazeli, M ; Keley, M ; Biazar, E ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    The current study deals with the preparation and characterization of polysaccharide-based biocomposite films acquired by the incorporation of cellulose nanofiber within glycerol plasticized matrix formed by starch. The application of starch-based films is limited due to highly hydrophilic nature and poor mechanical properties. These problems are solved by forming a nanocomposite of thermoplastic starch (TPS) as matrix and cellulose nanofiber (CNF) as reinforcement. CNF is successfully prepared from short henequen fibers which consist of almost 60% cellulose by a chemo-mechanical process. TPS/CNF composite films are prepared by the polymer solution casting method, and their characterizations... 

    Biomedical engineering of polysaccharide-based tissue adhesives: Recent advances and future direction

    , Article Carbohydrate Polymers ; Volume 295 , 2022 ; 01448617 (ISSN) Shokrani, H ; Shokrani, A ; Seidi, F ; Munir, M. T ; Rabiee, N ; Fatahi, Y ; Kucinska Lipka, J ; Saeb, M. R ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    Tissue adhesives have been widely used for preventing wound leaks, sever bleeding, as well as for enhancing drug delivery and biosensing. However, only a few among suggested platforms cover the circumstances required for high-adhesion strength and biocompatibility, without toxicity. Antibacterial properties, controllable degradation, encapsulation capacity, detectability by image-guided procedures and affordable price are also centered to on-demand tissue adhesives. Herein we overview the history of tissue adhesives, different types of polysaccharide-based tissue adhesives, their mechanism of gluing, and different applications of polysaccharide-based tissue adhesives. We also highlight the...