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Mechanical Properties of Actin Assemblies
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Actin filaments are the most abundant component of the cellular cytoskeleton and provide shape for the most eukaryotic cells. Actin constitutes 1-10% of the total protein in most cells and is present at even higher concentrations in muscle cells. The functions of actin are directly connected to its mechanical properties, therefore both experimental and computational understanding of the mechanical properties of actin filaments are essential to elucidate their functions in cells and muscles. Actin exists in two forms, actin monomers (G-actin) and actin filaments (F-actin), which have continuous polymerization and depolymerization processes. In the polymerization process, different...
Synthesis of Bone graft Substitute for Clinical Applications
, M.Sc. Thesis Sharif University of Technology ; Abdekhodaie, Mohammad Jafar (Supervisor)
Abstract
The natural tissue of the bones consists of organic and inorganic parts. The bone mineral part contains calcium phosphate and its organic part is mainly of collagen fibers. The combination of these fibers and calcium phosphate makes the bone flexible and resistant to stresses. Many conditions, including osteoporosis and crashes, lead to fractures and cavities in bone. Bone cements are the most used materials used in orthopedic surgeries and spinal cord.The purpose of this study was to synthesis acrylic bone cement with properties determined by ASTM F 451 and Iso5833 for orthopedic applications, including joint replacement. Polymethyl methacrylate polymer was synthesized as the main component...
Simulation and Control of Particle Size Distribution in a Continuous Emulsion Polymerization Reactor
, M.Sc. Thesis Sharif University of Technology ; Shahrokhi, Mohammad (Supervisor)
Abstract
In this work, a comprehensive dynamic model has been used for vinyl acetate emulsion polymerization in a continuous reactor to predict the evolution of product particle size distribution under isothermal condition. Method of finite-volume has been applied for solving the population balance equations and the results are compared with the results obtained from moment method. Finite-volume method has been selected as a precise technique to predict sustained oscillations, which occurs in continuous emulsion polymerization. After performing sensitivity analysis and verification of system’s controllability, feed rate of surfactant and initiator have been selected as proper manipulated variables to...
Synthesis and Investigation of Properties of Intumescent Fireproofing Paint with Oxide Nanoparticles
, M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem (Supervisor)
Abstract
Intumescent paints are coatings designed for passive fire protection of steel and other materials. In this research, the performance of water-based intumescent coating with vinyl acetate resin for cellulose fire conditions and epoxy-based coatings for hydrocarbon fire conditions has been investigated. The fire resistance of coatings was evaluated according to the ASTM E119 standard for water-based coating and UL1709 standard for epoxy-based intumescent coating. For the water-based intumescent coating, the expansion of char was investigated in a furnace with a temperature of 800°C for 1 hour. Thermal decomposition was studied by thermogravimetric analysis (TGA). Also, flammability was...
Preparation and Properties of Ethylene-vinyl Acetate/linear Low-density Polyethylene/Graphene Oxide Nanocomposite Films
, Article Polymer - Plastics Technology and Engineering ; Volume 54, Issue 11 , 2015 , Pages 1152-1158 ; 03602559 (ISSN) ; Ramazani, S. A ; Baniasadi, H ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
Ethylene-vinyl acetate-based nanocomposites with 18 and 28 wt% vinyl acetate were prepared via solution casting method. To improve the mechanical and barrier properties of ethylene-vinyl acetate, linear low-density polyethylene, and graphene oxide were introduced to matrix. The morphological studies indicated that the graphene oxide diffraction peak disappeared in all prepared nanocomposites, probably due to its exfoliation; also proper dispersion and good interaction between nanofillers and polymer matrix were achieved. By introducing low amount of graphene oxide into the matrix, the mechanical and thermal properties and oxygen permeability were improved especially for those with 28 wt%...
Poly(N-isopropylacrylamide)-coated β-cyclodextrin–capped magnetic mesoporous silica nanoparticles exhibiting thermal and pH dual response for triggered anticancer drug delivery
, Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 66, Issue 7 , 2017 , Pages 336-348 ; 00914037 (ISSN) ; Mazaheri Tehrani, Z ; Sharif University of Technology
Taylor and Francis Inc
2017
Abstract
In this research a novel controlled anticancer drug delivery system with dual pH and thermal responses was designed based on magnetic mesoporous silica nanoparticles that were anchored by β-cyclodextrin and coated by poly(N-isopropylacrylamide) (PNIPAM). Results demonstrated that the behavior of doxorubicin (anticancer drug) release depended on pH and temperature conditions. At endosomal pH (pH 5.5) the amount of drug release enhanced because the cap was removed from the pores. Furthermore, PNIPAM shell collapsed above the lower critical solution temperature and the releasing of drug increased. Thus, this nanocarrier would have the potential to be applied in the tumor therapy. © 2017 Taylor...
High molecular weight polyacrylamide nanoparticles prepared by inverse emulsion polymerization: reaction conditions-properties relationships
, Article Colloid and Polymer Science ; Volume 294, Issue 3 , 2016 , Pages 513-525 ; 0303402X (ISSN) ; Ramazani S. A ; Shaban, M ; Ayatollahi, S ; Tomovska, R ; Sharif University of Technology
Springer Verlag
2016
Abstract
High molecular weight polyacrylamide (PAM) nanoparticle dispersions are products with wide application possibilities, the most important of which is in petroleum industry such as drilling fluid and flooding agent in enhanced oil recovery. For that aim, it is necessary to achieve complete control of the final dispersion and polymer properties during the synthesis step. In this work, PAMs were synthesized by inverse emulsion polymerization of aqueous acrylamide solution in cyclohexane in the presence of emulsifier mixture of Span 20 and Span 80. We present a comprehensive study of the effects of variation of all important reaction conditions (agitation rate, reaction time and temperature,...
Effects of molecular structure on thermal, rheological and mechanical properties of drip irrigation PE tapes
, Article Journal of Polymer Research ; Volume 29, Issue 10 , 2022 ; 10229760 (ISSN) ; Pircheraghi, G ; Houshmandmoayed, S ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
Considering the microstructure-processing-properties relationship, the attempt was made to distinguish the main structural features of drip irrigation tape grades. In this regards, two different commercial polyethylene grades using for irrigation tape application (DB and MD samples) with various microstructural features were fully characterized by means of thermal, rheological and mechanical measurements and microscopic observations. A set of DSC techniques revealed that DB sample has faster crystallization kinetic probably due to its high crystallizable segments in chains and broad molecular weight distribution. It was found, the type of co-monomer used in DB sample is 1-hexene and in MD...
Surface modification of polysulfone ultrafiltration membranes by free radical graft polymerization of acrylic acid using response surface methodology
, Article Journal of Polymer Research ; Volume 26, Issue 9 , 2019 ; 10229760 (ISSN) ; Asadollahi, M ; Mousavi, S. A ; Bastani, D ; Aghaeifard, F ; Sharif University of Technology
Springer Netherlands
2019
Abstract
In this research, polysulfone (PSf) ultrafiltration (UF) membranes were prepared by a phase inversion method. Surface modification of the PSf membranes was carried out via grafting of acrylic acid as a hydrophilic monomer by free radical graft polymerization initiated by redox reaction. A central composite design (CCD) of response surface methodology (RSM) was applied to design the experiments. The process variables were acrylic acid concentration (CAA), redox system contact time (T1), and acrylic acid polymerization time (T2), while the contact angle (CA), pure water flux (PWF), and flux recovery ratio (FRR) were considered as the responses. Analysis of variance (ANOVA) demonstrated that...
A hybrid nanocomposite of poly(styrene-methyl methacrylate- acrylic acid) /clay as a novel rheology-improvement additive for drilling fluids
, Article Journal of Polymer Research ; Volume 26, Issue 2 , 2019 ; 10229760 (ISSN) ; Ghorbani, H ; Wood, D. A ; Abdollahi Khoshmardan, M ; Sharif University of Technology
Springer Netherlands
2019
Abstract
The hybrid-polymer nanocomposite poly(styrene-methyl methacrylate- acrylic acid) /nanoclay was synthesized by miniemulsion polymerization for novel use as a drilling fluid additive. Three low-solid-drilling fluids (bentonite-based; natural polymer-based; nanoclay-based) were formulated using the hybrid nanocomposite as an additive and their rheological performance compared. The polymer/clay hybrid nanoparticles significantly improve rheological and filtration properties of the drilling fluids and they remain stable at high pressure, high temperature and harsh salinity conditions. The fluids’ filtration properties improve as the concentration of the polymer/nanoclay-hybrid-nanoparticles...
Mathematical modeling of drug release from biodegradable polymeric microneedles
, Article Bio-Design and Manufacturing ; Volume 2, Issue 2 , 2019 , Pages 96-107 ; 20965524 (ISSN) ; Rabiee, M ; Rafizadeh, M ; Rabiee, N ; Shamsabadi, A. S ; Bagherzadeh, M ; Salarian, R ; Tahriri, M ; Tayebi, L ; Sharif University of Technology
Springer
2019
Abstract
Transdermal drug delivery systems have overcome many limitations of other drug administration routes, such as injection pain and first-pass metabolism following oral route, although transdermal drug delivery systems are limited to drugs with low molecular weight. Hence, new emerging technology allowing high molecular weight drug delivery across the skin—known as ‘microneedles’—has been developed, which creates microchannels that facilitate drug delivery. In this report, drug-loaded degradable conic microneedles are modeled to characterize the degradation rate and drug release profile. Since a lot of data are available for polylactic acid-co-glycolic acid (PLGA) degradation in the literature,...
A regioselective approach to synthesize indolyl diketone derivatives via magnetic polymeric copper-catalyst
, Article Catalysis Letters ; 2021 ; 1011372X (ISSN) ; Jarahiyan, A ; Pourjavadi, A ; Sharif University of Technology
Springer
2021
Abstract
Abstract: In the present paper, an efficient Cu-catalyzed regioselective acylation of indoles with phenylglyoxals was developed which is the first example of indolyl diketones synthesis by a heterogeneous catalyst. The magnetic polyacrylonitrile was synthesized through anchoring acrylonitrile monomers on Fe3O4 nanoparticles surface and then modified with 2-aminopyridine. At the final step, copper nanoparticles were immobilized onto the polymeric support containing stable ligands from functionalized nitrile groups of polyacrylonitrile. The different techniques such as Fourier transmission infrared spectroscopy, X-ray diffraction, Field emission scanning electron microscopy, Transmission...
A regioselective approach to synthesize indolyl diketone derivatives via magnetic polymeric copper-catalyst
, Article Catalysis Letters ; Volume 152, Issue 4 , 2022 , Pages 1119-1130 ; 1011372X (ISSN) ; Jarahiyan, A ; Pourjavadi, A ; Sharif University of Technology
Springer
2022
Abstract
Abstract: In the present paper, an efficient Cu-catalyzed regioselective acylation of indoles with phenylglyoxals was developed which is the first example of indolyl diketones synthesis by a heterogeneous catalyst. The magnetic polyacrylonitrile was synthesized through anchoring acrylonitrile monomers on Fe3O4 nanoparticles surface and then modified with 2-aminopyridine. At the final step, copper nanoparticles were immobilized onto the polymeric support containing stable ligands from functionalized nitrile groups of polyacrylonitrile. The different techniques such as Fourier transmission infrared spectroscopy, X-ray diffraction, Field emission scanning electron microscopy, Transmission...
Inhomogeneous and homogeneous swelling behavior of temperature-sensitive poly-(N-isopropylacrylamide) hydrogels
, Article Journal of Intelligent Material Systems and Structures ; Volume 27, Issue 3 , 2016 , Pages 324-336 ; 1045389X (ISSN) ; Baghani, M ; Naghdabadi, R ; Sharif University of Technology
SAGE Publications Ltd
Abstract
The aim of this work is to develop a model to continuously predict inhomogeneous and homogeneous swelling behavior of temperature-sensitive poly-(N-isopropylacrylamide) hydrogels. Employing this model, some benchmark homogeneous problems such as free, unidirectional constrained and biaxial constrained swelling as well as swelling of core-shell structures are investigated. The main advantage of the model is its ability to solve inhomogeneous deformations due to a stable behavior in the vicinity of the phase transition temperature. Therefore, inhomogeneous swelling of a spherical shell on a hard core with application to microfluidics is analytically and numerically investigated for various...
Preparation of porous graphene oxide/hydrogel nanocomposites and their ability for efficient adsorption of methylene blue
, Article RSC Advances ; Volume 6, Issue 13 , 2016 , Pages 10430-10437 ; 20462069 (ISSN) ; Nazari, M ; Kabiri, B ; Hosseini, S. H ; Bennett, C ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
Porous nanocomposite hydrogels were prepared using CaCO3 particles as solid porogens. The hydrogels were prepared by polymerization and grafting of acrylamide and 2-acrylamido-2-methylpropane sulfonic acid onto the starch in the presence of CaCO3 and graphene oxide. CaCO3 solid porogens were then removed by washing with acid and porous structures were obtained. The prepared hydrogels were used as adsorbents for methylene blue as a model cationic dye; and a very high adsorption capacity, up to 714.29 mg g-1, was obtained. Kinetics and isotherms of adsorption and the effect of porosity of hydrogel as well as other experimental conditions were also investigated. The prepared adsorbents were...
Improving mixed-matrix membrane performance: Via PMMA grafting from functionalized NH2-UiO-66
, Article Journal of Materials Chemistry A ; Volume 6, Issue 6 , 2018 , Pages 2775-2791 ; 20507488 (ISSN) ; Shojaei, A ; Mousavi, S. A ; Sharif University of Technology
Royal Society of Chemistry
2018
Abstract
The major obstacles in gas separation by mixed-matrix membranes (MMMs) are poor dispersion and poor affinity between polymers and fillers. The present study demonstrates that these challenges can be overcome appropriately by utilizing a series of synthesized stand-alone MMMs. The matrix used was polymethyl methacrylate (PMMA) and the MMMs were synthesized by in situ polymerization of methyl methacrylate (MMA) in the presence of UiO-66, NH2-UiO-66 and vinyl group attached UiO-66. In situ polymerization of MMA in the presence of vinyl attached UiO-66 resulted in PMMA grafted UiO-66 with a high degree of grafting. Microscopic analysis by field emission scanning electron microscopy (FESEM)...
Magnetic and light-responsive nanogels based on chitosan functionalized with Au nanoparticles and poly(: N-isopropylacrylamide) as a remotely triggered drug carrier
, Article New Journal of Chemistry ; Volume 44, Issue 40 , 2020 , Pages 17302-17312 ; Doroudian, M ; Bagherifard, M ; Bahmanpour, M ; Sharif University of Technology
Royal Society of Chemistry
2020
Abstract
In the past few years, laser-assisted methods have greatly influenced biomedical studies due to less invasive ways of treatment and higher precision. New stimuli-responsive drug carriers are still explored by scientists to achieve a better spatiotemporal control of drug carriers by using visible to NIR light instead of phototoxic ultra-violet irradiation. Due to their biocompatibility and high loading capacity of hydrophilic drugs, hydrogels have been used extensively in this area. However, poor cellular uptake and restricted loading of hydrophobic drugs are challenges that should be addressed. In this study, a previously known nanogel system based on chitosan and poly(N-isopropylacrylamide)...
A new functionalized magnetic nanocomposite of poly(methylacrylate) for the efficient removal of anionic dyes from aqueous media
, Article RSC Advances ; Volume 6, Issue 10 , 2016 , Pages 7982-7989 ; 20462069 (ISSN) ; Abedin Moghanaki, A ; Nasseri, S. A ; Sharif University of Technology
Royal Society of Chemistry
Abstract
A new magnetic nano-adsorbent was synthesized via the radical polymerization of methyl acrylate on modified Fe3O4 nanoparticles, followed by its functionalization by amidation of the methyl ester groups using pentaethylenehexamine, to create active adsorption sites for removing anionic dyes from aqueous media. Physicochemical properties of the adsorbent were then characterized by SEM, TEM, XRD, FTIR, TGA and CHN analysis. The prepared nanocomposite was used as adsorbent for the removal of anionic dyes, naphthol green B and chromeazurol S, from aqueous solution and assessed in view of the kinetics and isotherm adsorption, and the effect of solution pH, contact time and initial dye...
The role of mscl amphipathic n terminus indicates a blueprint for bilayer-mediated gating of mechanosensitive channels
, Article Nature Communications ; Volume 7 , 2016 ; 20411723 (ISSN) ; Cortes, D. M ; Cox, C. D ; Rohde, P. R ; Liu, W ; Deitmer, J. W ; Bavi, O ; Strop, P ; Hill, A. P ; Rees, D ; Corry, B ; Perozo, E ; Martinac, B ; Sharif University of Technology
Nature Publishing Group
2016
Abstract
The bacterial mechanosensitive channel MscL gates in response to membrane tension as a result of mechanical force transmitted directly to the channel from the lipid bilayer. MscL represents an excellent model system to study the basic biophysical principles of mechanosensory transduction. However, understanding of the essential structural components that transduce bilayer tension into channel gating remains incomplete. Here using multiple experimental and computational approaches, we demonstrate that the amphipathic N-terminal helix of MscL acts as a crucial structural element during tension-induced gating, both stabilizing the closed state and coupling the channel to the membrane. We...
Dendritic multi-walled carbon nanotube with thermoresponsive shells: A good carrier for anticancer drugs
, Article Journal of Industrial and Engineering Chemistry ; Volume 35 , 2016 , Pages 332-340 ; 1226086X (ISSN) ; Mazaheri Tehrani, Z ; Shirvani, T ; Doulabi, M ; Bumajdad, A ; Sharif University of Technology
Korean Society of Industrial Engineering Chemistry
Abstract
In this research, multi-walled carbon nanotubes (MWCNTs) were modified by dendritic macromonomer. Herein, polyamidoamine with acrylamide end groups was incorporated on MWCNTs. Afterwards, poly(N-isopropylacrylamide), (PNIPAM), was grafted on polyamidoamine in a facile synthesis. Then, doxorubicin as anticancer drug was loaded on this nanocarrier. The drug release was studied at below and above the lower critical solution temperature of PNIPAM, (LCST 32 °C), 27 °C and 37 °C, respectively. At 37 °C (body temperature) the polymer shell dehydrated and the drug release increased. The profile of drug release was expressed by Higuchi's equation which indicated that the drug release mechanism was...