Search for: biopolymers
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    Some investigations on bioflocculant producing bacteria

    , Article Biochemical Engineering Journal ; Volume 5, Issue 1 , 2000 , Pages 39-44 ; 1369703X (ISSN) Salehizadeh, H ; Vossoughi, M ; Alemzadeh, I ; Sharif University of Technology
    Bacillus sp. As-101 which produces flocculating substances was isolated from activated sludge, using a proteolytic enzyme. Bioflocculant As-101 was partially purified by cold ethanol and cetylpyridinium chloride. The partially purified flocculating substance was an acidic polysaccharide including uronic, pyruvic and acetic acids, respectively, in an approximate ratio of 11.4%, 6.1%, 0.4%. The biopolymer is also a sugar-protein derivative consisting of glucose, mannose and galactose. The protein, the sugar contents ratio is about 83-17%. Bioflocculant As-101 acted under acidic condition and the maximum activity was observed at optimum pH ˜ 3.7 and optimum concentration of 30 ppm in kaolin... 

    Optimization of microbial culture for production of poly hydroxy butyrate (PHB) by azotobacter beijerinckii DSMZ-1041

    , Article World Applied Sciences Journal ; Volume 14, Issue SPL ISS 3 , 2011 , Pages 72-82 ; 18184952 (ISSN) Montaser, N ; Ardjmand, M ; Nasab, A. H ; Kordi, A. S ; Sharif University of Technology
    Azotobacter beijerinckii DSMZ 1041 strain was used for production of polyhydroxybutyrate (PHB) and the optimum glucose concentration, as the carbon source and ammonium chloride, as the nitrogen source were obtained 60gr/lit and 0.5gr/lit respectively. The resulting optimum PHB production was investigated 2.95gr/lit. The obtained yield of PHB with respect to glucose (Yp/s) and PHB productivity (Qp) were 0.202 g/g and 0.123 g/lit.hr, respectively. The response surface methodology (RSM) was used to verify the accuracy of the designed experiments. azotobacter beijerinckii microorganism from Deutsch sammlung von microorganismen und zellkulturen(DSMZ) bank is used for production of Poly Hydroxy... 

    Investigation of optimum fermentation condition for PHA production by four species: Hydrogenophaga pseudoflava DSMZ 1034, azohydromonas lata DSMZ 1123, cupriavidus necator DSMZ 545, Azotobacter beijinckii DSMZ 1041

    , Article World Applied Sciences Journal ; Volume 14, Issue SPL ISS 3 , 2011 , Pages 36-47 ; 18184952 (ISSN) Karbasi, F ; Ardjmand, M ; Yunesi, H ; Safe Kordi, A ; Yaghmaei, S ; Sharif University of Technology
    Batch cultures of Azohydromonas lata DSMZ 1123, Hydrogenophaga pseudoflava DSMZ 1034, Cupriavidus necator DSMZ 545 and Azotobacter beijinckii DSMZ 1041 were investigated for producing the intracellular bioplastic poly-•-hydroxybutyrate (PHB). The effects of temperature, seed age, type of carbon sources and the agitation rate on the production rate of PHB were investigated using four mentioned spices. The optimized shaking rate, temperature and seed age were obtained 250 rpm, 30°C and 15 hrs for H. pseudoflava DSMZ 1034 and A. beijerinckii DSMZ 1041 and 18 hrs and 24 hrs for A. lata DSMZ 1123 and C. necator DSM 545, respectively.The effect of carbon sources including glucose, fructose, whey... 

    Synthesis and characterization of chitosan coating of NiFe2O4 nanoparticles for biomedical applications

    , Article Journal of the Iranian Chemical Society ; Volume 13, Issue 11 , 2016 , Pages 2069-2076 ; 1735207X (ISSN) Ramezani, S ; Ghazitabar, A ; Sadrnezhaad, S. K ; Sharif University of Technology
    Springer Verlag  2016
    Nickel ferrite nanoparticle is a soft magnetic material whose appealing properties as well as various technical applications have rendered it as one of the most attractive class of materials; its technical applications range from its utility as a sensor and catalyst to its utility in biomedical processes. The present paper focuses first on the synthesis of NiFe2O4 nanoparticles through co-precipitation method resulting in calcined nanoparticles that were achieved at different times and at a constant temperature (773 k). Afterward, they were dispersed in water that was mixed by chitosan. Chitosan was bonded on the surface of nanoparticles by controlling the pH of media. In order to assess the... 

    Axial potential mapping of optical tweezers for biopolymer stretching: The bead size matters

    , Article Optics Letters ; Volume 38, Issue 5 , 2013 , Pages 685-687 ; 01469592 (ISSN) Ahmadi, A ; Reihani, S. N. S ; Sharif University of Technology
    Optical tweezers (OT) are widely used for pico (and femto)-Newton range force measurements. The appropriate choice of the bead size is not well understood for biopolymer stretching applications of OT. We have shown, both by theory and experiment, that wrong choice of the bead size could cause errors as large as 295% in the measured force. We provide a simple map for correct choice of the bead size and the direction of pulling for such applications. There is a good agreement between our theoretical and experimental results  

    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
    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... 

    An overview on eco-friendly polymer composites for heavy metal ion remediation

    , Article Current Analytical Chemistry ; Volume 17, Issue 6 , 2021 , Pages 737-753 ; 15734110 (ISSN) Nazir, M. S ; Palvasha, B. A ; Tahir, Z ; Ul Hassan, S ; Ali, Z ; Akhtar, M. N ; Azam, K ; Abdullah, M. O ; Sharif University of Technology
    Bentham Science Publishers  2021
    Background: Water contamination by noxious heavy metals due to urbanization is a global environmental problem. Heavy metal ions pollution makes the water unsuitable for drinking and is also highly toxic to human beings and eco-system. The remediation of heavy metals is therefore very crucial. Methods: Adsorbents based on biopolymer and eco-friendly polymer composites have been developed and fabricated to remediate and remove heavy metals from the ecosystem. Results: In recent years biocomposites have been successful as cost-effective adsorbents for the remediation of various contaminants with their eco-friendly nature and sustainability. Conclusion: This review article gives an overview on... 

    Herschel-Bulkley rheological parameters of lightweight colloidal gas aphron (CGA) based fluids

    , Article Chemical Engineering Research and Design ; Volume 93 , 2015 , Pages 21-29 ; 02638762 (ISSN) Ziaee, H ; Arabloo, M ; Ghazanfari, M. H ; Rashtchian, D ; Sharif University of Technology
    Institution of Chemical Engineers  2015
    The proper understanding of rheological characteristics of CGA based fluids is of crucial importance in determining the performance of the fluid, in order to maintain the most effective fluid properties for safe, efficient, and economical drilling operation. This paper presents a concise investigation on the effect of concentration of the three main components of a novel environmentally friendly lightweight CGA based drilling fluid, i.e., xanthan gum biopolymer, starch, and biosurfactant, to the Herschel-Bulkley rheological model parameters. The three parameters of Herschel-Bulkley model, i.e., yield stress, fluid consistency, and fluid flow index were calculated by fitting the experimental... 

    Trends and challenges of biopolymer-based nanocomposites in food packaging

    , Article Comprehensive Reviews in Food Science and Food Safety ; Volume 20, Issue 6 , 2021 , Pages 5321-5344 ; 15414337 (ISSN) Taherimehr, M ; YousefniaPasha, H ; Tabatabaeekoloor, R ; Pesaranhajiabbas, E ; Sharif University of Technology
    John Wiley and Sons Inc  2021
    The ultimate goal of new food packaging technologies, in addition to maintaining the quality and safety of food for the consumer, is to consider environmental concerns and reduce its impacts. In this regard, one of the solutions is to use eco-friendly biopolymers instead of conventional petroleum-based polymers. However, the challenges of using biopolymers in the food packaging industry should be carefully evaluated, and techniques to eliminate or minimize their disadvantages should be investigated. Many studies have been conducted to improve the properties of biopolymer-based packaging materials to produce a favorable product for the food industry. This article reviews the structure of... 

    Polyacids for producing colloidally stable amorphous calcium carbonate clusters in water

    , Article Journal of Applied Polymer Science ; November , 2021 ; 00218995 (ISSN) Jia, X ; Basak Kayitmazer, A ; Ahmad, A ; Ramzan, N ; Li, Y ; Xu, Y ; Sun, S ; Sharif University of Technology
    John Wiley and Sons Inc  2021
    As an important precursor of crystalline phases, amorphous calcium carbonate (ACC), especially ultrasmall ACC clusters, have been attracting great interest in fundamental research, materials chemistry, as well as industrial applications. However, it is still challenging to synthesize stable ACC clusters in water that can be isolated and concentrated without severe aggregation. Herein, we report a facile dialysis method for producing colloidally stable ACC clusters that are well dispersed in water with the protection of specific polycarboxylic acids, which could be also easily deprotected by small-molecule acids like sodium citrate. Inherent proto-calcite short-range order is found to be... 

    Modified carrageenan. 4. Synthesis and swelling behavior of crosslinked ΚC-g-AMPS superabsorbent hydrogel with antisalt and pH-responsiveness properties

    , Article Journal of Applied Polymer Science ; Volume 98, Issue 1 , 2005 , Pages 255-263 ; 00218995 (ISSN) Pourjavadi, A ; Hosseinzadeh, H ; Mazidi, R ; Sharif University of Technology
    To synthesize a novel biopolymer-based superabsorbent hydrogel, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) was grafted onto kappa-carrageenan (ΚC) backbones. The graft copolymerization reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator, N,N,N′,N′-tetramethyl ethylenediamine (TMEDA) as an accelerator, and N,N′-methylene bisacrylamide (MBA) as a crosslinker. A proposed mechanism for ΚC-g-AMPS formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The affecting variables on swelling capacity, i.e., the initiator, the crosslinker, and the monomer concentration, as well as reaction temperature,... 

    Improving Temperature Stability of Drilling Fluids Polymers Using Nano Particles

    , M.Sc. Thesis Sharif University of Technology Halali, Mohamad Amin (Author) ; Ghotbi, Siroos (Supervisor)
    Water base drilling fluids are the most common drilling fluids in oil and gas operations and biopolymers are the requisite additives used in such kind of fluids frequently. Unfortunately, at harsh conditions of HPHT the polymers undergo thermal degradation which cause serious loss in fluid rheological and filtration properties. Accordingly, this will induce operational pitfalls and tremendous cost. The power of economy along with environmental regulations force us to search for reasonable chemically benign additives to fulfill this need. Nanoparticles are the most promising additives proposed in this study to address this challenge. Regarding their unique exclusive properties, they are able... 

    Immobilization Heavy Metal Ions and Nanoparticles (Au, Cu, Pd) on Biopolymers and Their Catalytic Activities in the Organic Reactions

    , Ph.D. Dissertation Sharif University of Technology Habibi, Zahra (Author) ; Pourjavadi, Ali (Supervisor)
    Recently, biopolymers such as alginate, cellulose, chitosan, gelatine, starch and wool have been used as supports for catalytic applications. Several interesting features of the biopolymers for example, bio-degradable, environmentally safe, high sorption capacity, physical and chemical versatility make them attractive to use as supports. This study, the four functionalized biopolymer-based composites were designed and synthesized as well as heterogeneous catalysts used in the synthesis of 1,2,3-triazoles, oxidation of alcohol, reduction of nitroarenes and carbon-carbon coupling reactions.A novel cellulose supported copper NHC complex has been prepared by the reaction of cellulose supported... 

    Study the Effect of Nano Particles on Biodegradability of Starch Biopolymers

    , M.Sc. Thesis Sharif University of Technology Ostadi, Hadi (Author) ; Vossoughi, Manoochehr (Supervisor) ; Alemzadeh, Iran (Supervisor)
    Nowadays, Food generation has gained great importance, not only in economic view but also in political. Food reservation is as important as food generation. Synthetic polymer films has widespread use in packaging industries, that is because of its features like easily forming, low price, lightness, etc. The increase of oil resources prices and severe environmental pollution by synthetic polymers, are notable cases which led researchers to find ways in using bio polymers. Starch is one of the bio polymers which is cheap and totally degradable. Using starch in bio degradable leads to high decrease in the mix features. Nano particles are used to solve the problem.
    In this study, the effect... 

    Enzyme Immobilization on Biopolymer Carrier by Microencapsulation Technique

    , M.Sc. Thesis Sharif University of Technology Hemmati, Mostafa (Author) ; Aalemzadeh, Iran (Supervisor) ; Vossoughi, Manouchehr (Supervisor)
    β-galactosidase enzyme is immobilized from Kluyveromyces lactis by Microencapsulation method in various compositions of sodium alginate and Carboxymethyl cellulose. Optimum stabilization was gained at 1.85% sodium alginate, 0.9% carboxymethyl cellulose and 2% calcium chloride through applying Surface response methodology. Yield of immobilization and activity was 54.94% and 65.27%. variation of yield of immobilization versus alginate concentration was a quadratic curve with the maximum. When alginate's concentrations is low, the cavities diameter is great, so the enzyme leaks from capsule while immobilizing. At high concentrations of alginate, despite the smaller cavities, immobilization... 

    Study of Viscoelastic Properties of Biopolymer Solutions

    , M.Sc. Thesis Sharif University of Technology Shahmoradi, Mohammad Reza (Author) ; Seyed Reihani, Nader (Supervisor)
    Properties of viscoelastic of biopolymers have important role in cells structure; for example: cell motility depends on viscoelastic propertie of Actin polymer. therefore according to its importance ,in this thesis we intend to examine the viscoelastic modulus using Optical tweezers and dissipation theorem.this method is benefits than methods of active microrheology. for example this method can be used for low concentrations; because in the low concentrations, the exerting force will cause changing in the state of matter that here we investigate destructive force effect. we investigate viscoelastic of water for method accuracy then obtain viscoelastic of Kelcogel  

    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... 

    Optimized synthesis of carrageenan-graft-poly(sodium acrylate) superabsorbent hydrogel using the Taguchi method and investigation of its metal ion absorption

    , Article Polymer International ; Volume 56, Issue 2 , 2007 , Pages 283-289 ; 09598103 (ISSN) Pourjavadi, A ; Amini Fazl, M. S ; Sharif University of Technology
    The Taguchi method, a robust experimental design, was used for the optimization of the synthesis of a novel biopolymer-based superabsorbent hydrogel, carrageenan-graft-poly(sodium acrylate). The Taguchi method was applied for the experiment and standard 16 orthogonal arrays with five factors and four levels for each factor were used. In the synthesis of the superabsorbent hydrogel, N,N′-methylene bisacrylamide (MBA) was used as crosslinker, ammonium persulfate as initiator, and acrylic acid as monomer. Neutralization percent and reaction temperature were used as important factors. The analysis of variance results showed that the most important factor in this synthesis was MBA concentration.... 

    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
    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,... 

    Shape-controlled silver NPs for shape-dependent biological activities

    , Article Micro and Nano Letters ; Volume 12, Issue 9 , 2017 , Pages 647-651 ; 17500443 (ISSN) Sadeghi, F ; Yazdanpanah, A ; Abrishamkar, A ; Moztarzadeh, F ; Ramedani, A ; Pouraghaie, S ; Shirinzadeh, H ; Samadikuchaksaraei, A ; Chauhan, N. P. S ; Hopkinson, L ; Sefat, F ; Mozafari, M ; Sharif University of Technology
    The most important issue during synthesis of nanoparticles (NPs) is to avoid particle agglomeration and adhesion. There have been several attempts to use special substances such as organic surfactants, polymers and stable ligands for this purpose. In this study, silver NPs were synthesised with and without gelatin macromolecules, as a green natural biopolymer, which resulted in NPs with varying shapes and sizes. The effect of morphological characteristics on the antibacterial and antifungal properties of the synthesised NPs were studied, by comparing Gram-negative (Escherichia coli) versus Gram-positive (Staphylococcus aureus) bacteria as well as fungi (Candida albicans) by calculation of...