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gamma-irradiation
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Gamma irradiation mediated synthesis of a new superabsorbent hydrogel network based on poly(acrylic acid) grafted onto salep
, Article Journal of the Iranian Chemical Society ; Volume 7, Issue 3 , 2010 , Pages 652-662 ; 1735207X (ISSN) ; Pourjavadi, A ; Soleyman, R ; Sheikh, N ; Sharif University of Technology
2010
Abstract
A novel and smart biopolymer-based hydrogel was synthesized by graft copolymerization of acrylic acid onto the salep backbones. The new superabsorbent hydrogel was synthesized via simultaneous crosslinking and graft copolymerization of acrylic acid (AA) monomer onto salep backbones using radiochemical methods. In radiochemical methods, γ-rays as initiator, energy source and crosslinker are applied. In our experiments, the effects of reaction variables such as relative contents of salep and AA, as well as γ-rays total dose were examined. According to water absorbency of the entitled network, the best synthesis condition is reported. FTIR spectroscopy, SEM photograph and TGA analysis were used...
Magnetic Nanocomposites Based on Biodegradable Plastic PVA and Effect of Gamma Irradiation
, M.Sc. Thesis Sharif University of Technology ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
Polyvinylalcohol/magnetite nanocomposite films were fabricated via solution casting. Magnetite (Fe3O4) nanoparticles were prepared by means of co-precipitation method and modified by citric acid. The nanoparticles and nanocomposites were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), vibrating sample magnetometer (VSM), fourier transform infrared spectroscopy (FTIR) and mechanical measurement. The results reveal that magnetite nanoparticles have a spherical shape with an average diameter of 19.7nm and are superparamagnetic at room temperature. The nanoparticles are observed to be uniformly dispersed in the polymer matrix due to a strong interaction between the...
Poly (vinyl alcohol)/nano-diamond composite films and hydrogels prepared by gamma ray
, Article Journal of Polymer Engineering ; Volume 38, Issue 9 , 2018 , Pages 857-862 ; 03346447 (ISSN) ; Dadbin, S ; Haddadi, S ; Sharif University of Technology
De Gruyter
2018
Abstract
Poly (vinyl alcohol) and nano-diamond, PVA/ND, hydrogels were prepared and assessed as prosthetic material suitable for replacement of the nucleus pulposus. The hydrogels were prepared by gamma irradiation at various doses (15 kGy, 25 kGy, 35 kGy, 45 kGy) and at various ND concentrations ranging from 0.25 wt.% to 3 wt.%. Extent of gelation, equilibrium water content, and viscoelastic properties of swelled hydrogels at definite water contents were measured and examined as a function of ND concentration as well as gamma dose. According to viscoelastic measurements, the strength of hydrogels increased considerably over that of pure PVA at a low concentration of ND. By increasing irradiation...
Preparation of Nanocomposites Based on PVA Hydrogel with CNT Via Gamma Irradiation
, M.Sc. Thesis Sharif University of Technology ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
Polyvinylalcohol/MWCNT nanocomposite films were fabricated via solution casting method. Glycerol was added to the polymer matrix as plasticizer in order to improve the flexibility and toughness of resultant films. Surface modification of MWCNTs were carried out by subjecting to gamma irradiation of 60Co source to total doses of 50.0 and 75 kGy in pure ethanol and in a solution with equal volume fraction of water and ethanol. The produced nanocomposites in each case which contain different type of modified MWCNTs were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), mechanical and electrical measurements. The...
PLA/PVAc Nano-Blends for Barrier Films: Effect of Gamma Irradiation
, M.Sc. Thesis Sharif University of Technology ; Forounchi, Massoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
Oxygen barrier properties of poly (lactic acid) (PLA) films were improved by blending it with hydrolyzed poly (vinyl acetate). Poly (vinyl acetate-co-vinyl alcohol) with vinyl alcohol contents of 0, 5, 10 and 15% was prepared using acid-catalyzed hydrolysis of poly (vinyl acetate). The Blend films of PLA/poly (VAc-co-VA) containing 0, 5, 10 and 15% of the copolymer with various degree of hydrolysis was prepared by solution-casting method. Effect of gamma irradiation on the films was examined by exposing them to radiation doses of 0, 20, 35 and 50 kGy. The films remained colorless and transparent after irradiation. Morphology of the samples characterized by optical microscopy displayed not...
Irradiation mediated synthesis of a superabsorbent hydrogel network based on polyacrylamide grafted onto salep
, Article Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms ; Volume 266, Issue 18 , September , 2008 , Pages 3932-3938 ; 0168583X (ISSN) ; Pourjavadi, A ; Soleyman, R ; Sheikh, N ; Sharif University of Technology
2008
Abstract
The synthesis and swelling behavior of a new superabsorbent hydrogel based on natural salep grafted with polyacrylamide is described. The new biopolymer was synthesized via simultaneous crosslinking and graft copolymerization of acrylamide monomer onto a salep backbone using radiochemical methods. Various parameters such as relative contents of salep and acrylamide, as well as total dose of γ-rays were examined. The best synthesis condition is reported and a mechanism for superabsorbent hydrogel formation suggested. Factors affecting the swelling behavior of hydrogel were also studied. © 2008 Elsevier B.V. All rights reserved
Poly (Vinyl Alcohol) Hydrogel/Nano-diamond as a Replacement for the Nucleus Pulposus
, M.Sc. Thesis Sharif University of Technology ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
The nucleus pulposus, which is a part of intervertebral disc, is normally hydrated and gel-like to maintain normal biomechanical functions of the disc through intradiscal pressures. In a degenerated disc, however, water content of nucleus is significantly reduced, resulting in an abnormal stress state of the annulus. Surgical interventions cannot restore the biomedical function to vertebral segment. One approach to restore the normal biomechanics of an intervertebral disc is to replace the nucleus with a prosthetic material which leads to a restoration of the behavior of the disc. The mechanical behavior of poly(vinyl alcohol) and nanodiamond hydrogel may provide a material suitable for...
Preparation of Gelatin/Pva Porous Scaffolds by Chemical and Gamma Irradiation Methods for Skin Cell Culture
, M.Sc. Thesis Sharif University of Technology ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
The goal of this research project was to prepare gelatin/PVA porous scaffolds by chemical and gamma irradiation methods to be used for human dermal fibroblast cell culture. First, the polymers were dissolved in hot water and mixed properly to achieve a homogenous solution. The mixture was then frozen at -200C and immersed in ethanol/ glutaraldehyde solution at -200C for 48 hours in order to extract ice crystals and also form chemical crosslinks in gelatin by glutaraldehyde. After being rinsed with distilled water the samples were lyophilized. The effects of polymers solution concentration, gelatin/PVA ratio and glutaraldehyde /gelatin ratio were investigated on characteristics of the...
Grafting of acrylamide onto kappa-carrageenan via γ-irradiation: Optimization and swelling behavior
, Article Radiation Physics and Chemistry ; Volume 77, Issue 2 , 2008 , Pages 131-137 ; 0969806X (ISSN) ; Pourjavadi, A ; Sheikh, N ; Sadegh Amini Fazl, M ; Sharif University of Technology
2008
Abstract
The Taguchi method, a robust experimental design for optimization, was used for the synthesis of a superabsorbent hydrogel network using γ-rays as an initiator, energy source and crosslinker at the same time. Nine different samples of superabsorbent hydrogels were prepared in various conditions from kappa-carrageenan (κC) and acrylamide by γ-irradiation at room temperature. Considering the results of nine trials and according to analysis of variance (ANOVA), a new experimental condition with the concentrations of κC and acrylamide 1.5 g and 0.028 mol (2 g in total volume of 50 mL H2O), respectively, as well as γ-ray at the optimum total dose (7 kGy) was proposed. After preparing the desired...
Fabrication of Porous Gelatin-based Scaffold and Evaluation of Effect of Gamma Irradiation
, M.Sc. Thesis Sharif University of Technology ; Forounchi, Massoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
Biocompatible porous polymeric scaffolds provide a suitable 3-D environment for proliferation of stem cells in human body. For instance, growth and proliferation concurrent with differentiation of stem cells in such scaffolds can regenerate the tissues or organs. In this attitude we fabricated a porous Gelatin-based scaffold using both of freeze-drying and freeze-extraction methods.Also, effect fo gamma irradiation on microstructure of scaffolds was investigated. In addition, poly(ethylene glycol) was employed to make the scaffold softer. Moreover, effects of various parameters including freezing temperature, cross-linking agent concentration, gelatin and PEG concentrations and their...
The Fabrication of Porous Scaffolds of Polyvinyl Chloride/Polyethylene Glycol and Nano Diamonds Using Gamma Radiation for Medical Applications
, M.Sc. Thesis Sharif University of Technology ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
Today, tissue engineering research is expanding to a large extent, so tissue engineering has the ability to build artificial organs and tissues. In this project, we have used two polymers of polyethylene glycol and polyvinyl chloride, which are used for network irradiation. After irradiation, these polymers were made by drying the freewheeling porous scaffolds and the effect of different parameters on the structure of these scaffolds was investigated. To investigate the effect of different factors on gelation, swelling, tensile test, degradability and finally the conditions of fibroplast cell growth on scaffolds were investigated. The results of the gel test showed that the gel was higher...
Preparation of Porous PVA Nanocomposite Hydrogels Via Gamma Irradiation
, M.Sc. Thesis Sharif University of Technology ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
In this research, porous polyvinyl¬ alcohol (PVA)/Montmorillonite nanoclay and polyvinyl alcohol/polyvinyl pyrrolidone (PVP)/Montmorillonite nanoclay nanocomposite sponges (foams) were fabricated by freeze-drying method. The foams were crosslinked using gamma irradiation. The pore size and interconnectivity of nanocomposites characterized by scanning electron microscopy (SEM), showed bimodal pore size distribution resulting from preparation method.
SEM micrographs displayed that addition of PVP ( wt% of total solid polymer) to the PVA sponges increased the pore size and interconnectivity, due to the optimal number of hydrogen bonds between functional groups of polymeric matrices....
SEM micrographs displayed that addition of PVP ( wt% of total solid polymer) to the PVA sponges increased the pore size and interconnectivity, due to the optimal number of hydrogen bonds between functional groups of polymeric matrices....
Design of Multi-purpose Gamma Irradiator System Based on Combined Monte Carlo Geant4 and GPU Hardware
, M.Sc. Thesis Sharif University of Technology ; Sohrabpour, Mostafa (Supervisor)
Abstract
Gamma irradiation systems are used extensively in the industry in order to sterilize medical devices, disinfect hygienic materials or increase the shelf life of agricultural produce. The method of gamma irradiation is superior to the older methods of heat or chemical treatment because it is by far a simpler operation. In this method only a single parameter of time is controlled whereas in the other mentioned methods five or six different parameters need to be controlled. The design of irradiation systems including the size, location of products and arrangement of source rack pencils. In order to optimize the design it is needed to study the products dose distribution in a wide range of...
PVP-PEG-BaTiO3 Hydrogels, Synthesis and Characterization for Medical Applications
, M.Sc. Thesis Sharif University of Technology ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
Today, hydrogels have various biomedical applications as three-dimensional networks with the ability to absorb and retain water and biological fluids. This study aimed to prepare nanocomposite hydrogels from polyvinyl pyrrolidone, polyethylene glycol, and barium titanate nanoparticles. Gamma radiation at irradiation doses of 25 and 35 kGy was used as the hydrogel's crosslinking agent. The effects of gamma irradiation dose, percentage of polyethylene glycol, and barium titanate composition on the swelling ratio and gel content were investigated. It was observed that the amount of gel content with the addition of polyethylene glycol and barium titanate nanoparticles reduces the gel content and...
Monitoring of Ion Implanter Radiation
, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bizhan (Supervisor)
Abstract
X-ray radiation is an ionizing radiation that can be produced under some conditions in an ion implanter and can have significant effects on equipment and personnel health. In this dissertation, we first examine the properties of ionizing radiations and their effects of electronic devices and discuss the general properties of common detectors. Next, Using Silvaco TCAD and GEANT4 we will simulate the interaction of ionzing radiation with energies up to 300 keV with electronic devices including a commercial off the shelf photo diode and a specialized x-ray detector and show that these devices can efficiently reveal informations of a radiation source to the user. Also, it has been shown that...
Inactivation methods for whole influenza vaccine production
, Article Reviews in Medical Virology ; Volume 29, Issue 6 , 2019 ; 10529276 (ISSN) ; Miri, S. M ; Keshavarz, M ; Zargar, M ; Ghaemi, A ; Sharif University of Technology]
John Wiley and Sons Ltd
2019
Abstract
Despite tremendous efforts toward vaccination, influenza remains an ongoing global threat. The induction of strain-specific neutralizing antibody responses is a common phenomenon during vaccination with the current inactivated influenza vaccines, so the protective effect of these vaccines is mostly strain-specific. There is an essential need for the development of next-generation vaccines, with a broad range of immunogenicity against antigenically drifted or shifted influenza viruses. Here, we evaluate the potential of whole inactivated vaccines, based on chemical and physical methods, as well as new approaches to generate cross-protective immune responses. We also consider the mechanisms by...
Nano-magnetic poly (vinyl alcohol) hydrogels
, Article Advanced Materials Research ; Volume 829 , 2014 , Pages 539-543 ; ISSN: 10226680 ; ISBN: 9783037859070 ; Frounchi, M ; Dadbin, S ; Sharif University of Technology
Abstract
Surface modified magnetic nanoparticles (M-NPs) were synthetized and stabilized in poly (vinylalcohol) solution. The solutions with various magnetic nanoparticles contents were gammairradiated and magnetic poly (vinyl-alcohol) (M-PVA) hydrogels were synthesized. The magnetic hydrogels and also the un-irradiated magnetic poly (vinyl alcohol) nanocomposite films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR) and mechanical measurement. The M-NPs were uniformly dispersed in the polymer matrix due to a strong interaction between the surface-modified M-NPs and polymer matrix....
PLA microspheres-embedded pva hydrogels prepared by gamma-irradiation and freeze-thaw methods as drug release carriers
, Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 62, Issue 1 , 2013 , Pages 28-33 ; 00914037 (ISSN) ; Dadbin, S ; Frounchi, M ; Sharif University of Technology
2013
Abstract
A drug delivery system based on poly (vinyl alcohol) (PVA) hydrogels containing ibuprofen-loaded poly (lactic acid) (PLA) microspheres was developed to improve the release kinetics of this model drug. Gamma-irradiation and freeze-thawing were applied to prepare poly (vinyl alcohol) hydrogels. Properties and morphology of these composite hydrogels were investigated using FTIR, DSC, and SEM. In vitro release indicated that entrapment of the microspheres into the PVA hydrogels causes a reduction in both the release rate and the initial burst effect. PLA microspheres entrapped into the PVA hydrogels showed more suitable controlled release kinetics for drug delivery
Effect of gamma ray on magnetic bio-nanocomposite
, Article Materials Chemistry and Physics ; Volume 170 , 2016 , Pages 71-76 ; 02540584 (ISSN) ; Frounchi, M ; Dadbin, S ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Magnetic polyvinyl alcohol (M-PVA) films were prepared via solution casting filled with surface modified superparamagnetic nanoparticles (M-NPs). The M-NPs were coated with citric acid during synthesis. The chemical interaction between the citric acid and M-NPs was confirmed by Fourier transform infrared spectroscopy (FTIR). The average hydrodynamic diameter of M-NPs was 19.7 nm measured by dynamic light scattering DLS and appeared almost spherical in scanning electron microscopy (SEM). The M-NPs were uniformly dispersed in polyvinyl alcohol (PVA) matrix and showed high optical transparency with good mechanical properties. M-PVA hydrogels were synthesized using gamma irradiation. The...
Polyvinyl alcohol and polyvinyl alcohol/ polyvinyl pyrrolidone biomedical foams crosslinked by gamma irradiation
, Article Journal of Cellular Plastics ; Volume 53, Issue 4 , 2017 , Pages 359-372 ; 0021955X (ISSN) ; Frounchi, M ; Dadbin, S ; Sharif University of Technology
SAGE Publications Ltd
2017
Abstract
Foams for biomedical applications were made from polyvinyl alcohol, polyvinyl alcohol / polyvinyl pyrrolidone blend and their nanocomposites with nanoclay by clean processes. Air was entrapped into the aqueous polymer solutions during vigorous mixing and then the solutions were freeze-dried. The foams structure was stabilized by crosslinking via gamma irradiation without using any harmful chemicals. The hydrophilic biocompatible foams possessed interconnected open cell structure with remarkable capacity to absorb and retain water. The foams in wet state were soft and flexible. Desirable pore structure and higher water absorption was obtained at a solution concentration of 5 wt% for both...