Loading...
Search for:
moosavi-mehr--s--h
0.155 seconds
Total 16351 records
Solvent-, ion- and pH-specific swelling of poly(2-acrylamido-2- methylpropane sulfonic acid) superabsorbing gels
, Article Journal of Polymer Research ; Volume 17, Issue 2 , 2010 , Pages 203-212 ; 10229760 (ISSN) ; Zohuriaan Mehr, M. J ; Mirzadeh, H ; Kheirabadi, M ; Sharif University of Technology
2010
Abstract
Homopolymer hydrogel of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and its nanocomposite counterpart were prepared to study their swelling properties. The hydrogels showed ability to absorb and retain electrolytes as well as binary mixtures of water and organic solvents (i.e., methanol, ethanol, acetone, ethylene glycol (EG), polyethylene glycol, N-methyl-2-pyrrolidone (NMP), and dimethylsulfoxide (DMSO). The nanocomposite gel exhibited lower swelling in all solvent compositions in comparison with non-composite gel. Unlike conventional acrylic acid-based hydrogels, the poly(AMPS) gels showed superabsorbing capacity in pure ethanol, methanol, EG, DMSO and NMP. Meanwhile, swelling...
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) ; 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-...
Detection of distributed denial of service attacks using statistical pre-processor and unsupervised neural networks
, Article First International Conference on Information Security, Practice and Experience, ISPEC 2005, 11 April 2005 through 14 April 2005 ; Volume 3439 , 2005 , Pages 192-203 ; 03029743 (ISSN) ; Imani Mehr, F ; Amini, M ; Shahriari, H. R ; Sharif University of Technology
Springer Verlag
2005
Abstract
Although the prevention of Distributed Denial of Service (DDoS) attacks is not possible, detection of such attacks plays main role in preventing their progress. In the flooding attacks, especially new sophisticated DDoS, the attacker floods the network traffic toward the target computer by sending pseudo-normal packets. Therefore, multi-purpose IDSs do not offer a good performance (and accuracy) in detecting such kinds of attacks. In this paper, a novel method for detection of DDoS attacks has been introduced based on a statistical pre-processor and an unsupervised artificial neural net. In addition, SPUNNID system has been designed based on the proposed method. The statistical...
Modified CMC. 4. Ceric-initiated methacrylonitrile graft polymerization onto carboxymethylcellulose
, Article Journal of Polymer Materials ; Volume 21, Issue 4s , 2004 , Pages 351-359 ; 09738622 (ISSN) ; Zohuriaan Mehr, M. J ; Pooraghaberar, A ; Hosseinzadeh, H ; Sharif University of Technology
2004
Abstract
Graft copolymerization of methacrylonitrile (MAN) onto carboxymethylcellulose (CMC) was carried out under argon atmosphere in a homogeneous aqueous medium by using ceric ammonium nitrate (CAN) as an initiator. The FTIR spectroscopy and solubility characteristics of the products were used for confirming the graft copolymer formation. The effect of the concentration of the initiator, monomer and polysaccharide as well as the reaction time and temperature on the graft copolymerization reactions were investigated to achieve the optimum grafting conditions (i.e. CAN 0.00065 mol/L, MAN 0.85 mol/L, CMC 1% W/V, reaction temperature 45°C, and reaction time 2 h). According to the empirical rates of...
Super alcohol-absorbent gels of sulfonic acid-contained poly(acrylic acid)
, Article Journal of Polymer Research ; Volume 18, Issue 3 , 2011 , Pages 449-458 ; 10229760 (ISSN) ; Lashani, S ; Zohuriaan Mehr, M. J ; Kheirabadi, M ; Sharif University of Technology
2011
Abstract
Alcohol-specific superabsorbing gels (superalcogels) based on non-neutralized acrylic acid (AA, 60-94 mol%) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) were prepared via solution polymerization in water. Polyethylene glycol dimethacrylate and potassium persulfate were used as crosslinker and initiator, respectively. Characterization of samples was performed using FTIR, 1H-NMR and thermomechanical analyses. Glass transition temperature and modulus of dried samples were found to be directly changed with their AA content. The gels exhibited enormous ability for absorbing and retaining a variety of mono- and poly-hydric alcohols. For example, in lieu of one gram of a typical sample...
Carrageenan-g-poly(sodium acrylate)/kaolin superabsorbent hydrogel composites: Synthesis, characterisation and swelling behaviour
, Article Polymers and Polymer Composites ; Volume 15, Issue 1 , 2007 , Pages 43-51 ; 09673911 (ISSN) ; Hosseinzadeh, H ; Mahdavinia, G. R ; Zohuriaan Mehr, M. J ; Sharif University of Technology
Rapra Technology Ltd
2007
Abstract
A novel superabsorbent hydrogel composite based on kappa-carrageenan (κC) was prepared by graft copolymerisation of acrylic acid (AA) in the presence of kaolin using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. The synthetic variables (i.e. AA, MBA and APS concentration, and the amount of kaolin) affecting the water absorbency of the resulting superabsorbent composite were studied. Evidence of grafting and kaolin interaction was obtained by comparing the FTIR spectra of the initial substrates and of the superabsorbent composite. A new absorption band at 1722 cm-1 in the composite spectrum confirmed the kaolin-organic polymer linkage....
Modified chitosan. I. Optimized cerium ammonium nitrate-induced synthesis of chitosan-graft-polyacrylonitrile
, Article Journal of Applied Polymer Science ; Volume 88, Issue 8 , 2003 , Pages 2048-2054 ; 00218995 (ISSN) ; Mahdavinia, G. R ; Zohuriaan Mehr, M. J ; Omidian, H ; Sharif University of Technology
2003
Abstract
Chitin was extracted from shrimp shells and then deacetylated to obtain chitosan. The degree of deacetylation of the chitosan was determined to be 0.76 using pH-metric titration. A large number of cyanide functional groups were introduced onto chitosan by grafting with polyacrylonitrile as an efficient way of modification. The graft copolymerization reactions were carried out under argon atmosphere in a homogeneous aqueous phase (containing a small portion of acetic acid) by using eerie ammonium nitrate as an initiator. Evidence of grafting was obtained by comparing FTIR spectra of chitosan and the graft copolymer as well as solubility characteristics of the products. The synthetic...
Energy efficiency through joint routing and function placement in different modes of SDN/NFV networks
, Article Computer Networks ; Volume 200 , 2021 ; 13891286 (ISSN) ; Parsaeefard, S ; Maddah Ali, M. A ; Shah-Mansouri, V ; Khalaj, B. H ; Bennis, M ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Network function virtualization (NFV) and software-defined networking (SDN) are two promising technologies to enable 5G and 6G services and achieve cost reduction, network scalability, and deployment flexibility. However, migration to full SDN/NFV networks in order to serve these services is a time-consuming process and costly for mobile operators. This paper focuses on energy efficiency during the transition of mobile core networks (MCN) to full SDN/NFV networks and explores how energy efficiency can be addressed during such migration. We propose a general system model containing a combination of legacy nodes and links, in addition to newly introduced NFV and SDN nodes. We refer to this...
Temporal Congestion Games
, M.Sc. Thesis Sharif University of Technology ; Ghodsi, Mohammad (Supervisor)
Abstract
We consider a special class of Congestion Games enhanced with a notion of time.Network Routing problems, such as road traffic networks, computer neworks, and evacuation problems are some applications of this class of games. Two subclasses of these games, namely atomic and non-atomic is considered in this article, both of them introduced in 2009. Some of the existing results are Nash equilibria existence proof for “single-source single-sink” case, and a mechanism for improving price of anarchy in the non-atomic subclass. There are also some results in the atomic subclass of this game.We extend both models of atomic and non-atomic subclasses to “multi-source,multi-sink” configurations. We call...
Study of Biomolecules Imaging Using Molecular Dynamics Simulations
, Article Nano ; Volume 10, Issue 7 , October , 2015 ; 17932920 (ISSN) ; Nejat Pishkenari, H ; Moosavi, A ; Meghdari, A ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
2015
Abstract
The process of imaging a biomolecule by atomic force microscope (AFM) is modeled using molecular dynamics (MD) simulations. Since the large normal force exerted by the tip on the biosample in contact and tapping modes may damage the sample structure and produce irreversible deformation, the noncontact mode of AFM (NC-AFM) is employed as the operating mode. The biosample is scanned using a carbon nanotube (CNT) as the AFM probe. CNTs because of their small diameter, high aspect ratio and high mechanical resistance attract many attentions for imaging purposes. The tip-sample interaction is simulated by the MD method. The protein, which has been considered as the biomolecule, is ubiquitin and a...
Geometry effect on electrokinetic flow and ionic conductance in pH-regulated nanochannels
, Article Physics of Fluids ; Volume 29, Issue 12 , 2017 ; 10706631 (ISSN) ; Saidi, M. H ; Moosavi, A ; Sadeghi, A ; Sharif University of Technology
2017
Abstract
Semi-analytical solutions are obtained for the electrical potential, electroosmotic velocity, ionic conductance, and surface physicochemical properties associated with long pH-regulated nanochannels of arbitrary but constant cross-sectional area. The effects of electric double layer overlap, multiple ionic species, and surface association/dissociation reactions are all taken into account, assuming low surface potentials. The method of analysis includes series solutions which the pertinent coefficients are obtained by applying the wall boundary conditions using either of the least-squares or point matching techniques. Although the procedure is general enough to be applied to almost any...
A comprehensive review on recent advances in superhydrophobic surfaces and their applications for drag reduction
, Article Progress in Organic Coatings ; Volume 140 , March , 2020 ; Pakzad, H ; Moosavi, A ; Nouri Borujerdi, A ; Sharif University of Technology
Elsevier B. V
2020
Abstract
Nowadays, superhydrophobic surfaces have attracted a lot of interest because of the wide range of applications in industries. These surfaces can significantly reduce the drag force due to the formation of air gaps between the substrate and liquid interface. The present review mainly focuses on the very recent progresses in the drag reduction studies using superhydrophobic surfaces. Also, a brief discussion about the mathematical modeling and the theories of superhydrophobic surfaces, natural water repellent surfaces, various fabrication techniques with advantages and disadvantages of each method and different properties of the fabricated surfaces in industrial applications is presented....
Unsteady solute dispersion by electrokinetic flow in a polyelectrolyte layer-grafted rectangular microchannel with wall absorption
, Article Journal of Fluid Mechanics ; Volume 887 , 2020 ; Saidi, M. H ; Moosavi, A ; Sadeghi, A ; Sharif University of Technology
Cambridge University Press
2020
Abstract
The dispersion of a neutral solute band by electrokinetic flow in polyelectrolyte layer (PEL)-grafted rectangular/slit microchannels is theoretically studied. The flow is assumed to be both steady and fully developed and a first-order irreversible reaction is considered at the wall to account for probable surface adsorption of solutes. Considering low electric potentials, analytical solutions are obtained for electric potential, fluid velocity and solute concentration. Special solutions are also obtained for the case without wall adsorption. To track the dispersion properties of the solute band, the generalized dispersion model is adopted by considering the exchange, the convection and the...
Tuning electrokinetic flow, ionic conductance, and selectivity in a solid-state nanopore modified with a pH-responsive polyelectrolyte brush: A molecular theory approach
, Article Journal of Physical Chemistry C ; Volume 124, Issue 34 , 2020 , Pages 18513-18531 ; Saidi, M. H ; Moosavi, A ; Kröger, M ; Sharif University of Technology
American Chemical Society
2020
Abstract
We use an efficient molecular theory approach to study electrokinetic flow within a pH-responsive nanopore grafted with a polyelectrolyte (PE) brush. The flow rate, migration and convective conductance, electric potential and velocity fields, species distributions and the degree of ionization of the weak PE functional groups and nanopore selectivity are obtained and interpreted while considering pH-induced surface charges. The theory is generally based on writing the overall free energy of the system including the entropies arising from the conformations of flexible, excluded volume chains, the mixing of mobile species, electrostatic contribution, and the free energy due to the chemical...
Superhydrophobic home-made polyurethane sponges for versatile and cost-effective oil and water separation
, Article Separation and Purification Technology ; Volume 276 , 2021 ; 13835866 (ISSN) ; Pakzad, H ; Fakhri, M ; Moosavi, A ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Utilizing 3D and 2D porous materials modified by a superhydrophobic/philic coating for quick removal of oil from water and a continuous process of oil/water separation, respectively, has attracted a lot of attention recently. Here we report the separation capacities of one commercial and three home-made sponges, sprayed by a superhydrophobic coating, for a broad range of oils and solvents. The contact angle of water on the coated sponges is 162.5˚, whereas the pristine sponge shows a contact angle of 91.8˚ (these values are for sponge D which had the highest absorption capacity). We investigate the effects of the density of sponges and the dynamic viscosity of oils and solvents on the...
Modified CMC: part 1- optimized synthesis of carboxymethylcellulose-g-polyacrylonitrile [electronic resource]
, Article Iranian Polymer Journal ; Vol. 14, No 2, 131-138, 2005 ; 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,...
Microfluidic systems for stem cell-based neural tissue engineering
, Article Lab on a Chip - Miniaturisation for Chemistry and Biology ; Volume 16, Issue 14 , 2016 , Pages 2551-2571 ; 14730197 (ISSN) ; Bahrami, S ; Mirshekari, H ; Moosavi Basri, S. M ; Bakhshian Nik, A ; Aref, A. R ; Akbari, M ; Hamblin, M. R ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
Neural tissue engineering aims at developing novel approaches for the treatment of diseases of the nervous system, by providing a permissive environment for the growth and differentiation of neural cells. Three-dimensional (3D) cell culture systems provide a closer biomimetic environment, and promote better cell differentiation and improved cell function, than could be achieved by conventional two-dimensional (2D) culture systems. With the recent advances in the discovery and introduction of different types of stem cells for tissue engineering, microfluidic platforms have provided an improved microenvironment for the 3D-culture of stem cells. Microfluidic systems can provide more precise...
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 ; 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 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 ; 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...
Coarsening dynamics of dewetting nanodroplets on chemically patterned substrates
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 86, Issue 1 , July , 2012 ; 15393755 (ISSN) ; Sharif University of Technology
2012
Abstract
Mesoscopic hydrodynamic equations are solved to investigate coarsening dynamics of two interacting nanodroplets on chemically patterned substrates. The effects of different parameters such as the surface chemical pattern, the slip length, the profile of the disjoining pressure, the size of the droplets, and the contact angles on the coarsening are studied. Our results reveal that the presence of a chemical heterogeneity can enhance or weaken the coarsening dynamics depending on the pattern type and positions of the droplets on the substrate. Also increasing the contact angles to values larger than a critical value may qualitatively change the coarsening process, and the profile of the...