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    Modified carrageenan. 5. Preparation, swelling behavior, salt- and pH-sensitivity of partially hydrolyzed crosslinked carrageenan-graft-polymethacrylamide superabsorbent hydrogel [electronic resource]

    , Article Polymers for Advanced Technologies ; Volume 15, Issue 11, pages 645–653, November 2004 Pourjavadi, A. (Ali) ; Sadeghi, M ; Hosseinzadeh, H
    Abstract
    The polysaccharide, kappa-carrageenan (κC) was chemically modified to achieve a novel superabsorbent hydrogel via graft copolymerization of methacrylamide (MAM) onto the substrate followed by alkaline hydrolysis. Ammonium persulfate (APS) and N,N′-methylene bisacrylamide (MBA) were used as a free-radical initiator and a crosslinker, respectively. The saponification reaction was carried out using sodium hydroxide aqueous solution. Either κC-g-PMAM or hydrolyzed κC-g-PMAM (PMAM: polymethacrylamide) was characterized by FT-IR spectroscopy. The effect of grafting variables (i.e. concentration of MBA, MAM, and APS) and alkaline hydrolysis conditions (i.e. NaOH concentration, hydrolysis time and... 

    Modified carrageenan. 4. Synthesis and swelling behavior of crosslinked kappa C-g-AMPS superabsorbent hydrogel with antisalt and pH-responsiveness properties [electronic resource]

    , Article Journal of Applied Polymer Science ; Vol.98, No.1, 255-263, 2005 Pourjavadi, A. (Ali) ; Hosseinzadeh, H ; Mazidi, R
    Abstract
    To synthesize a novel biopolymer-based superabsorbent hydrogel, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) was grafted onto kappa-carrageenan (KC) 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 KC-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,... 

    Partially hydrolyzed crosslinked alginate-graft-polymethacrylamide as a novel biopolymer-based superabsorbent hydrogel having pH-responsive Properties [electronic resource]

    , Article Macromolecular Research ; January 2005, Volume 13, Issue 1, pp 45-53 Pourjavadi, A. (Ali) ; Aminfazl, M. S ; Hosseinzadeh, H
    Abstract
    In this study, a series of highly swelling hydrogels based on sodium alginate (NaAlg) and polymethacrylamide (PMAM) was prepared through free radical polymerization. The graft copolymerization reaction was performed in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator andN,N′-methylenebisacrylamide (MBA) as a crosslinker. The crosslinked graft copolymer, alginate-graft-polymethacrylamide (Alg-g-PMAM), was then partially hydrolyzed by NaOH solution to yield a hydrogel, hydrolyzed alginate-graft-polymethacrylamide (H-Alg-g-PMAM). During alkaline hydrolysis, the carboxamide groups of Alg-g-PMAM were converted into hydrophilic carboxylate anions. Either the... 

    Wideband 5 W Ka-Band GaAs Power Amplifier

    , Article IEEE Microwave and Wireless Components Letters ; Volume 26, Issue 8 , 2016 , Pages 622-624 ; 15311309 (ISSN) Hosseinzadeh, N ; Medi, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Abstract
    This letter presents a Ka-Band 0.1-μm GaAs pHEMT Power Amplifier with broad bandwidth. The isolating backvia wall (IBVW) has been proposed to improve the stability and performance. Over the frequency band of 31-40 GHz, implemented PA delivers 5 W saturated output power, 28% maximum power added efficiency (PAE) and 20 dB maximum small-signal gain. The chip size of the PA is 11.9 mm2. To the best of authors knowledge, the presented PA demonstrates widest bandwidth in Ka-band GaAs PAs while maintaining compact size  

    Quantum integrability of 1D ionic hubbard model

    , Article Annalen der Physik ; Volume 532, Issue 3 , 2020 Hosseinzadeh, A ; Jafari, S. A ; Sharif University of Technology
    Wiley-VCH Verlag  2020
    Abstract
    The quantum integrability of the 1D ionic Hubbard model (IHM) is established using two independent numerical methods, namely i) energy level spacing statistics and ii) occupation profile of one-particle density matrix (OPDM) eigen-values. Both methods suggest that the 1D IHM is integrable. The calculations of energy level statistics reproduce the known results for the standard Hubbard model. Upon turning on the the ionic term, the energy level spacing distribution of this model continues to obey the Poissonian distribution. Occupation patterns as extracted from OPDM indicate that quasi-particles are sharpened upon increasing the ionic potential. This is evidenced by a larger jump in the... 

    Generalization of Lieb–Wu wave function inspired by one-dimensional ionic Hubbard model

    , Article Annals of Physics ; Volume 414 , 2020 Hosseinzadeh, A ; Jafari, S. A ; Sharif University of Technology
    Academic Press Inc  2020
    Abstract
    With the ionic Hubbard model (IHM) in mind, we construct a non-trivial generalization of the Bethe ansatz (BA) wave function which naturally generalizes the Lieb–Wu wave function with an ionic parameter Δ, and reduces to Lieb–Wu solution in the limit Δ→0. The resulting two-particle scattering matrix satisfies the Yang–Baxter equation. To the extent that the unit cells with more than two electrons (Choy–Haldane issue) are avoided on average, our wave function represents an effective solution for the one-dimensional IHM. The Choy–Haldane issue limits the validity of our solution to low-filling and large U≳4. This regime is attainable in cold atom realizations of the IHM. For this regime, we... 

    Imprimitivity index of the adjacency matrix of digraphs

    , Article Linear Algebra and Its Applications ; Volume 517 , 2017 , Pages 1-10 ; 00243795 (ISSN) Akbari, S ; Ghodrati, A. H ; Hosseinzadeh, M. A ; Sharif University of Technology
    Elsevier Inc  2017
    Abstract
    Let G be a graph. An edge orientation of G is called smooth if the in-degree and the out-degree of every vertex differ by at most one. In this paper, we show that if G is a 2-edge-connected non-bipartite graph with δ(G)≥3, then G has a smooth primitive orientation. Among other results, using the spectral radius of digraphs, we show that if D1 is a primitive regular orientation and D2 is a non-regular orientation of a given graph, then for sufficiently large t, the number of closed walks of length t in D1 is more than the number of closed walks of length t in D2. © 2016 Elsevier Inc  

    Some lower bounds for the energy of graphs

    , Article Linear Algebra and Its Applications ; Volume 591 , 2020 , Pages 205-214 Akbari, S ; Ghodrati, A. H ; Hosseinzadeh, M. A ; Sharif University of Technology
    Elsevier Inc  2020
    Abstract
    The singular values of a matrix A are defined as the square roots of the eigenvalues of A⁎A, and the energy of A denoted by E(A) is the sum of its singular values. The energy of a graph G, E(G), is defined as the sum of absolute values of the eigenvalues of its adjacency matrix. In this paper, we prove that if A is a Hermitian matrix with the block form A=(BDD⁎C), then E(A)≥2E(D). Also, we show that if G is a graph and H is a spanning subgraph of G such that E(H) is an edge cut of G, then E(H)≤E(G), i.e., adding any number of edges to each part of a bipartite graph does not decrease its energy. Let G be a connected graph of order n and size m with the adjacency matrix A. It is well-known... 

    A lightweight defense approach to mitigate version number and rank attacks in low-power and lossy networks

    , Article Wireless Personal Communications ; Volume 99, Issue 2 , March , 2018 , Pages 1035-1059 ; 09296212 (ISSN) Nikravan, M ; Movaghar, A ; Hosseinzadeh, M ; Sharif University of Technology
    Springer New York LLC  2018
    Abstract
    The Internet of Things (IoT) presents a new paradigm of the future internet that intends to provide interactive communication between various processing object via heterogeneous networks. The routing protocol in the IoT environment is Routing Protocol for Low-Power and Lossy Networks (RPL). The current RPL specification defines primary security modes; therefore it is vulnerable to topological attacks. In this paper the RPL routing mechanism, its topological vulnerabilities and two important topological attacks namely version number attack and rank spoofing attack are analyzed. To counter the mentioned attacks, a lightweight Identity Based Offline–Online Signature based scheme is proposed.... 

    Correction to: a lightweight signcryption scheme for defense against fragment duplication attack in the 6LoWPAN networks

    , Article Peer-to-Peer Networking and Applications ; 7 June , 2018 , Pages 1- ; 19366442 (ISSN) Nikravan, M ; Movaghar, A ; Hosseinzadeh, M ; Sharif University of Technology
    Springer New York LLC  2018
    Abstract
    The Publisher regrets an incorrect figure was placed in the pdf version of the article. © 2018 Springer Science+Business Media, LLC, part of Springer Nature  

    A lightweight signcryption scheme for defense against fragment duplication attack in the 6LoWPAN networks

    , Article Peer-to-Peer Networking and Applications ; 2018 , Pages 1-18 ; 19366442 (ISSN) Nikravan, M ; Movaghar, A ; Hosseinzadeh, M ; Sharif University of Technology
    Springer New York LLC  2018
    Abstract
    The Internet of Things (IoT) presents a new paradigm of the future Internet that intends to provide interactive communication between various processing objects via heterogeneous networks. The IPv6 over Low power Wireless Personal Area Networks (6LoWPAN) is an IPv6 adaptation sub-layer and provides the requirements of IP connectivity between resource-constrained devices in lossy, low power networks. Since the size of a packet in the IPv6 is larger than the size of a frame in the IEEE 802.15.4, the 6LoWPAN adaptation layer performs packet fragmentation. In this paper, first, the 6LoWPAN fragmentation mechanism in terms of security issues is analyzed and then, fragment duplication attack which... 

    TSRN: A tabu search-based routing protocol for named data networking

    , Article Wireless Personal Communications ; Volume 101, Issue 3 , 2018 , Pages 1411-1428 ; 09296212 (ISSN) Shariat, Z ; Movaghar, A ; Hosseinzadeh, M ; Sharif University of Technology
    Springer New York LLC  2018
    Abstract
    Information-centric network (ICN) has become a basic research topic with regard to the future architecture of the Internet. Storage and routing data is an important feature of ICN, as it improves network performance and content distribution. One of the challenges in this type of network is the routing problem. The objective of this paper is to propose a routing algorithm in the named data network. Owing to the impressive results presented by the enhanced heuristic methods, tabu search has been selected to develop the proposed algorithm. This work has been carried out in five major steps, Creating the initial solution, The mechanisms of generating a neighborhood, Evaluating the neighbor... 

    Equimatchable regular graphs

    , Article Journal of Graph Theory ; Volume 87, Issue 1 , 2018 , Pages 35-45 ; 03649024 (ISSN) Akbari, S ; Ghodrati, A. H ; Hosseinzadeh, M. A ; Iranmanesh, A ; Sharif University of Technology
    Wiley-Liss Inc  2018
    Abstract
    A graph is called equimatchable if all of its maximal matchings have the same size. Kawarabayashi, Plummer, and Saito showed that the only connected equimatchable 3-regular graphs are K4 and K3, 3. We extend this result by showing that for an odd positive integer r, if G is a connected equimatchable r-regular graph, then G ϵ {Kr+1, Kr,r}. Also it is proved that for an even r, a connected triangle-free equimatchable r-regular graph is isomorphic to one of the graphs C5, C7, and Kr,r. © 2017 Wiley Periodicals, Inc  

    Modified carrageenan. 1. H-carragPAM, a novel biopolymer-based superabsorbent hydrogel [electronic resource]

    , Article Journal of Bioactive and Compatible Polymers ; September 2005 Vol. 20 no. 5 475-490 Hosseinzadeh, H. (Hossein) ; Pourjavadi, A ; Mahdavinia, G. R ; Zohuriaan-Mehr, , M. J
    Abstract
    A novel kappa-carrageenan (C)-based superabsorbing hydrogel was synthesized through graft copolymerization of acrylamide (AAm) onto a C substrate in the presence of a crosslinking agent. The crosslinked C-poly(AAm) polymer graft was partially hydrolyzed in alkaline medium to yield a superabsorbent resin, H-carragPAM. The resin structure was confirmed using FTIR spectroscopy. The variables of graft copolymerization (monomer, initiator, polysaccharide and crosslinker concentration, reaction temperature and time as well as stirrer speed) that affected on the ultimate water-swelling capacity were optimized. The time-temperature variation of the copolymerization was investigated in terms of the... 

    On the energy of line graphs

    , Article Linear Algebra and Its Applications ; Volume 636 , 2022 , Pages 143-153 ; 00243795 (ISSN) Akbari, S ; Alazemi, A ; Anđelić, M ; Hosseinzadeh, M. A ; Sharif University of Technology
    Elsevier Inc  2022
    Abstract
    The energy of a graph G, E(G), is defined as the sum of absolute values of the eigenvalues of its adjacency matrix. In Akbari and Hosseinzadeh (2020) [3] it was conjectured that for every graph G with maximum degree Δ(G) and minimum degree δ(G) whose adjacency matrix is non-singular, E(G)≥Δ(G)+δ(G) and the equality holds if and only if G is a complete graph. Let G be a connected graph with the edge set E(G). In this paper, first we show that E(L(G))≥|E(G)|+Δ(G)−5, where L(G) denotes the line graph of G. Next, using this result, we prove the validity of the conjecture for the line of each connected graph of order at least 7. © 2021 Elsevier Inc  

    Aggregate interference modelling and static resource allocation in closed and open access femtocells

    , Article IET Communications ; Vol. 8, issue. 7 , May , 2014 , pp. 1007-1016 ; 1751-8628 Hosseinzadeh-Salati, A. S ; Nasiri-Kenari, M ; Sharif University of Technology
    2014
    Abstract
    Femtocell has appeared as a solution to increase both the coverage and the capacity of cellular networks. However, interference problem between the macrocell and the femtocell must be solved before any deployment. Since femtocells are deployed by home users in random locations, decentralised interference management schemes remain worth of investigation. In this study, the author deal with the problem of aggregate interference modelling and static resource allocation in orthogonal frequency division multiple access (OFDMA)-based two-tier femtocell networks for both closed and open access femtocells. It is assumed that for macrocell users (MUs), spectrum allocation is accomplished through... 

    The relationships between Wiener index, stability number and clique number of composite graphs

    , Article Bulletin of the Malaysian Mathematical Sciences Society ; Volume 36, Issue 1 , 2012 , Pages 165-172 ; 01266705 (ISSN) Doslic, T ; Ghorbani, M ; Hosseinzadeh, M. A ; Sharif University of Technology
    2012
    Abstract
    Some new relations have been established between Wiener indices, stability numbers and clique numbers for several classes of composite graphs that arise via graph products. For three of considered operations we show that they make a multiplicative pair with the clique number  

    Solvent-free dehydration of alcohols using LiCI-acidicalumina

    , Article Oriental Journal of Chemistry ; Volume 28, Issue 3 , 2012 , Pages 1141-1145 ; 0970020X (ISSN) Bagheri Marandi, G ; Pourjavadi, A ; Hosseinzadeh, H ; Sharif University of Technology
    2012
    Abstract
    Conjugated enynes, dienes and simple olefins have been cleanly and selectively synthesized, good-to-excellent yields, by dehydration of corresponding alcohols using focused microwave irradiation on the surface of LiCI-acidic alumina  

    Full-polysaccharide superabsorbent hydrogels based on carboxymethylcellulose and sodium alginate

    , Article Journal of Polymer Materials ; Volume 23, Issue 1 , 2006 , Pages 61-69 ; 09738622 (ISSN) Hosseinzadeh, H ; Pourjavadi, A ; Madhavinia, G. R ; Sharif University of Technology
    2006
    Abstract
    A novel full-polysaccharide superabsorbent hydrogel was synthesized via chemical crosslinking of carboxymethylcellulose (CMC) and sodium alginate (Alg) using epichlorohydrine (ECH) as a crosslinker. A proposed mechanism for hydrogel formation was suggested and the structure of the product was established using FTIR spectroscopy. The influence of ECH concentration and Alg/CMC weight ratio as well as reaction time and temperature on water and saline (0.9 wt% NaCl) absorbency of the hydrogels were systematically investigated. Meanwhile, the overall activation energy for the crosslinking reaction between CMC and Alg polysaccharides was estimated to be 11.6 kj/mol. Under the optimised conditions... 

    Modified carrageenan. 6. Crosslinked graft copolymer of methacrylic acid and kappa-carrageenan as a novel superabsorbent hydrogel with low salt- and high pH-sensitivity

    , Article Macromolecular Research ; Volume 13, Issue 6 , 2005 , Pages 483-490 ; 15985032 (ISSN) Pourjavadi, A ; Harzandi, A. M ; Hosseinzadeh, H ; Sharif University of Technology
    Polymer Society of Korea  2005
    Abstract
    A novel, polysaccharide-based, superabsorbent hydrogel was synthesized through crosslinking graft copolymerization of methacrylic acid (MAA) onto kappa-carrageenan (κC), using ammonium persulfate (APS) as a free radical initiator in the presence of methylenebisacrylamide (MBA) as a crosslinker. A proposed mechanism for κC-g-polymethacrylic acid (κC-g-PMAA) formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The effect of grafting variables, including MBA, MAA, and APS concentration, was systematically optimized to achieve a hydrogel with the maximum possible swelling capacity. The swelling kinetics in distilled water and various salt solutions were...