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khozaei-ravari--mojtaba
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Fabrication and characterization of an injectable reinforced composite scaffold for cartilage tissue engineering: An in vitro study
, Article Biomedical Materials (Bristol) ; Volume 16, Issue 4 , 2021 ; 17486041 (ISSN) ; Mashayekhan, S ; Zarei, F ; Sayyahpour, F. A ; Taghiyar, L ; Eslaminejad, M. B ; Sharif University of Technology
IOP Publishing Ltd
2021
Abstract
There are limitations in current medications of articular cartilage injuries. Although injectable bioactive hydrogels are promising options, they have decreased biomechanical performance. Researchers should consider many factors when providing solutions to overcome these challenges. In this study, we created an injectable composite hydrogel from chitosan and human acellular cartilage extracellular matrix (ECM) particles. In order to enhance its mechanical properties, we reinforced this hydrogel with microporous microspheres composed of the same materials as the structural building blocks of the scaffold. Articular cartilage from human donors was decellularized by a combination of physical,...
Fabrication of Composite Scaffold Composed of Cartilage Extracellular Matrix/Chitosan with High Mechanical Strength for Cartilage Tissue Engineering
, M.Sc. Thesis Sharif University of Technology ; Mashayekhan, Shohreh (Supervisor) ; Baghban Eslami Nejad, Mohammad Reza (Supervisor)
Abstract
Methods that has been used for articular defects are faced with many limitations, so new therapies based on tissue engineering were taken into consideration in recent years. However, tissue engineering also encounters challenges regarding optimal scaffold construction and suitable cell source selection. Mature harvested chondrocytes are limited in number and may lose their chondrogenic potential in several cultures, leading to dedifferentiation. In addition, using stem cells also presents unique challenges associated with them, among which hypertrophic differentiation is the most substantial problem. Choosing the appropriate biomaterial similar to the cartilage structure with sufficient...
Measurement of Radionuclide Transport Parameters for Soil Samples Taken from Naein Radioactive Waste Disposal Site by Using Column Experiment and Determining the Concentration Profile through the Column
, M.Sc. Thesis Sharif University of Technology ; Samadfaam, Mohammad (Supervisor)
Abstract
Radioactive wastes are generated at different stages of the nuclear fuel cycle and other activities related to the handling of the radioactive substances. In order to protect human being and the environment from any harmful effects of ionizing radiation, it’s necessary to isolate radioactive waste by disposing them in near surface or deep geological formations (depending on the radioactive hazard). To ensure that the waste is properly isolated from the environment for required periods of time, the safety assessment of the disposal site is essential. Transport of radionuclides from the disposal site to the environment is the essential part at any safety assessment program. Therefore,...
Optical Conductivity of Fermi Arc States
, M.Sc. Thesis Sharif University of Technology ; Jafari, Akbar (Supervisor)
Abstract
Recently, some materials, such as Weyl and Dirac semimetals, have been found in condensed matter physics whose band structure behaves like Weyl fermions of elementary particles near some points of the first Birillouin zone. The Weyl equation that governs these materials, have boundary because they are finite. By applying proper boundary conditions, two-dimensional surface states have been emerged. these states are called fermi arc sates because the surface corresponding to the fermi energy is not a closed surface. Surface states are mixed with bulk states because by getting close to the end of fermi arcs, surface states tend to bulk states con-tinuously. Being able to distinguish between...
A semantic aware access control model with real time constraints on history of accesses
, Article Proceedings of the International Multiconference on Computer Science and Information Technology, IMCSIT 2008, 20 October 2008 through 22 October 2008, Wisla ; Volume 3 , 2008 , Pages 827-836 ; 9788360810149 (ISBN); 9788360810149 (ISBN) ; Amini, M ; Jalili, R ; Sharif University of Technology
2008
Abstract
With the advent of semantic technology, access control cannot be done in a safe way unless the access decision takes into account the semantic relationships among the entities in a semantic-aware environment. SBAC model considers this issue in its decision making process. However, time plays a crucial role in new computing environments which is not supported in the model. In this paper we introduce the Temporal Semantic Based Access Control model (TSBAC), as an extension of SBAC, which enhances the specification of user-defined authorization rules by constraining time interval and temporal expression over users' history of accesses. A formal semantics for temporal authorizations is provided...
A temporal semantic-based access control model
, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 559-568 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Amini, M ; Jalili, R ; Sharif University of Technology
2008
Abstract
With the advent of semantic technology, access control cannot be done in a safe way unless the access decision takes into account the semantic relationships between entities in a semantic-aware environment. SBAC model considers this issue in the decision making process. However, time plays a crucial role in new computing environments which is not supported in this model. In this paper we introduce temporal semantic based access control model (TSBAC), as an extension of SBAC model, which enhances the specification of user-defined authorization rules by constraining time interval and temporal expression over users' history of accesses. A formal semantics for temporal authorizations is provided...
Broadcast Efficient Verifiable Secret Sharing
, M.Sc. Thesis Sharif University of Technology ; Izadi, Mohammad (Supervisor)
Abstract
Verifiable secret sharing (VSS) is one of the basic problems in the theory of distributed cryptography and has important role in secure multi-party computation. In this case, it is tried to share a confidential data as secret, between multiple nodes in a distributed system, in the presence of an active adversary that can destroy a number of nodes, such that the secret can be reconstructed with the participation of certain size of honest nodes. There are two types of active adversary; Static and dynamic which the latter can change it’s corrupted nodes among the protocol. VSS protocols have different types of algorithmic complexity and one of these definitions, is the use of broadcast channel...
Reinforcement Learning Approach in Self-Assembly Systems to Acquire Desired Structures
, M.Sc. Thesis Sharif University of Technology ; Bagheri Shouraki, Saeed (Supervisor)
Abstract
Self-Assembly (SA) plays a critical role in the formation of different phenomena in nature. This phenomenon can be defined as an arrangement of meaningful patterns with the aggregate behavior of simpler structures. One of the examples of Self-Assembly can be considered of the formation of ice crystals from ice molecules. Previous works mainly focus on graph grammar and self-assembly in fully observable environments. These algorithms mainly consist of two main stages: first, constructing simpler structures and then joining these simpler structures to form a complex structure. The challenges of the previous work can be considered as the necessity of a central controller in the formation of...
GTHBAC: A generalized temporal history based access control model
, Article Telecommunication Systems ; Volume 45, Issue 2-3 , 2010 , Pages 111-125 ; 10184864 (ISSN) ; Haadi Jafarian, J ; Amini, M ; Jalili, R ; Sharif University of Technology
2010
Abstract
Time plays a crucial role in access control for new computing environments, which is not supported in traditional access control models. In this paper, we propose a Generalized Temporal History Based Access Control (GTHBAC) model, aimed at integrating history-based constraints along with a generic access control model. GTHBAC enhances the specification of user-defined authorization rules by constraining time interval and temporal expression over users' history of accesses. Due to different application needs, GTHBAC uses two different time schemes, i.e., real time and logical time, in its authorization rules. A formal semantics for temporal authorizations is provided, and conflicting...
A history based semantic aware access control model using logical time
, Article Proceedings of 11th International Conference on Computer and Information Technology, ICCIT 2008, 25 December 2008 through 27 December 2008, Khulna ; 2008 , Pages 43-50 ; 9781424421367 (ISBN) ; Amini, M ; Jalili, R ; Jafarian, J. H ; Sharif University of Technology
2008
Abstract
With the advent of semantic technology' access control cannot be done in a safe way unless the access decision takes into account the semantic relationships among the entities in a semantic-aware environment. The SBAC model (Semantic Based Access Control model) considers this issue in its decision making process. However' time plays a crucial role in new computing environments'which is not supported in SBAC. In this paper' we propose the Temporal Semantic Based Access Control (TSBAC) model' as an extension of SBAC' which enhances the specification of user-defined authorization rules by constraining time interval and temporal expression over users' history of accesses. TSBAC uses logical...
Position Error of Resolver in a Closed Loop Control
, M.Sc. Thesis Sharif University of Technology ; Nasiri Gheidari, Zahra (Supervisor)
Abstract
Permanent Magnet Synchronous Motors (PMSMs) are more conventional and widely employed in Electric Vehicles (EVs) applications. The rotor position performed an essential role through PMSMs drive; therefore, any deviation in the detected position will be evaded in coordinate transformations, originating from external or inherence sources. Subsequently, the discussed faults will be conducted to three-phase currents and output torque through erroneous transformations. Resolver’s estimated rotor position due to fault occurrence will be defined as aggregating ideal and non-ideal components. Moreover, based on inherence periodic in resolvers’ principle, non-ideal components could be written by the...
Financial Contagion ,Interbank Market, and Central Bank Policy
, M.Sc. Thesis Sharif University of Technology ; Madanizadeh, Ali (Supervisor) ; Mahmoodzadeh, Amineh (Supervisor)
Abstract
Financial distress can propagate through different channels such as bank run, deposit interbank market,networks and asset prices. In this paper, with the assumption of deposit insurance, no linkages between banks, no deposit interbank market and fixed asset prices, we show that asset-side shocks might propagate through both loan interbank market and deposit market. However, when there is aggregate liquidity surplus in the banking system, loan interbank market results in the first best allocation. In contrast, aggregate liquidity shortage does not result in optimum allocation. In the presence of deposit and loan interbank market, not only shocks propagate but also they are magnified with the...
Synthesis of Triethylamine by Microfluidics
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Ali Asghar (Supervisor) ; Bastani, Dariush (Supervisor)
Abstract
Chemical reactions are a fundamental issue in industrial applications, and also tertiary amines are valuable materials in the paint and drug industries. Recently, the use of microreactors for organic reactions has drawn much attention. The typical dimensions of microreactors are in the range of 10–500 mm. Because of this microstructure and high surface-area–to–volume ratio, it has particularly excellent heat and mass transfer characteristics. In such a reaction system, almost every site has the same temperature, so the phenomenon of local overheating or local overcooling can be avoided. Compared with conventional macroscale batch reactors, the microreactor has excellent features, such as...
Preparation, Surface Modification and Application of Nanocomposite Membranes Based on Transition Metals- Dichalcogenide Nanoparticles in Forward Osmosis Desalination Process
, Ph.D. Dissertation Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor) ; Ahadian, Mohammad Mahdi (Supervisor) ; Amini, Mojtaba (Supervisor)
Abstract
Different parts of this research are focused on developing FO membranes and improving their performance. For this purpose, thin film composite (TFC) membranes with fixed composition of polyethersulfone/polyamide (PES/PA) have been used to investigate the effect of nanocomposites containing transition metal dichalcogenides (TMDs) on their performance. The support layer in all cases is PES, which is prepared through the phase inversion process and does not contain any nanofillers. The modification process takes place in the polyamide layer by dispersing the desired nanoparticles in the aqueous monomer solution necessary to form this active layer. Identification and characterization of...
Synthesis, Structure and Catalytic Application of Mn, Fe and Mo Complexes with Schiff base and Oxazoline ligands and Theoretical Mechanistic Studies on the Role of Heme and non-Heme Iron(IV)-Oxo Species in Hydroxylation and Epoxidation Reactions
, Ph.D. Dissertation Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
The first part of this thesis describes the synthesis and characterization of several Mn, Fe and Mo complexes containing tridentate Schiff base and oxazoline ligands and their reactivities as catalysts in the oxidation of organic compounds like olefins and sulfides, as well. The crystal structures of newly prepared cis-dioxo-bis[2-(2′-hydroxyphenyl)-oxazolinato]molybdenum(VI), cis-[MoO2(phox)2] and (N-hydroxyphenyl-salicylidenamine)(acetylacetonato)ethanol iron(III), [FeIII(N-OPh-sal)(acac)EtOH] complexes have been described by X-ray crystallography. Due to the difficulties in the preparation of suitable single crystals of novel...
Design and Fabrication of RFID Front END Transceiver single chip with 2.5W Output Power
, Ph.D. Dissertation Sharif University of Technology ; Atarodi, Mojtaba (Supervisor)
Abstract
This thesis deals with the front-End of an Integrated RFID Reader operated in 860MHz to 960MHz, which integrates a RF transceiver including PA, LNA and Mixer. In the receiver part, a power amplifier was fabricated and measured and in the transmitter part, LNA and Mixer were designed. There is a growing interest in utilizing CMOS technologies for RF power amplifiers (PAs). Although several advances have been made recently to enable full integration of PAs in CMOS, it is still among the most difficult challenges in achieving a truly single-chip radio system in CMOS. This is exacerbated by supply voltage reduction due to CMOS technology scaling and on-chip passive losses due to the conductive...
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
Inert gold become catalytically active when dispersed in the form of nanoparticles. Isolated gold nanoparticles have demonstrated high catalytic activity for both oxidation and reduction reactions. In order to obtain high catalytic activity, gold nanoparticles are generally dispersed on support materials, among which oxides are commonly used. However, a substantial decrease in activity and selectivity of the immobilized catalysts is frequently observed due to the heterogeneous nature of these support materials in reaction media. In the course of our study on the metal-based catalysis for synthesis of organic compounds, we herein report that rod-shaped Au nanoparticles in aqua solution...
Synthesis and Characterization of a novel Ruthenium(II) Complex With Bidentate O,N-donor OxazolineLigand and Study of Catalytic Oxidation of Sulfides and Alkanes
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
The 2-(2′-hydroxyphenyl)-oxazoline ligand (Hphox) is generated from 1:1 condensation of methyl salicylate with 2-aminoethanol. Novel [Ru(Hphox)2(H2O)2] (Hphox = 2-(2′-hydroxyphenyl)-oxazoline ) complex has been synthesized and characterized by physic-chemical methods. Oxidation of sulfides catalyzed by the mixed-ligand ruthenium(II) complex [Ru(Hphox)2(H2O)2]using urea-hydrogen peroxide (UHP) as oxidant was investigated under mild condition within 1 h. The results showed that mixed-ligand ruthenium(II) complex was effective catalyst in oxidation of sulfides in whichsulfoxideswere the only products. Using this catalytic system in the oxidation of alkanes, ketones were obtained as the main...
Synthesis of Core-Shell Nanoparticles Supported Iron and Vanadium Schiff Base and Their Application as a Catalyst for Oxidation of Sulfides, Alcohols and Olefins
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
In this work, synthesized Fe3O4 magnetic nanoparticles andcoated with SiO2 to prepare magnetic core-shell nanoparticles. Then immobilized Schiff baseof iron and vanadium complexes on magnetic core-shell nanoparticles was prepared as a recoverable magnetic nano catalysts. These catalysts were named Fe3O4@SiO2@L1@Fe, Fe3O4@SiO2@L2@Fe and Fe3O4@SiO2@L3@V. Furthermore,olefines epoxidation, sulfides and alcohols oxidation were studied with using iron and vanadium magnetic nano catalysts. The supported catalysts were characterized by atomic absorption, FT-IR and UV–Vis spectra.The catalytic performance of the synthesized iron catalyst was tested for the epoxidation of cyclohexene, styrene and...
Preparation of Heterogeneous Catalysts by Immobilization of Molybdenum and Manganese-shiff Base Complexes into the Nanopores of Zeolite and SBA-15
, Ph.D. Dissertation Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
This thesisconsiders new fundamental approaches to yield heterogeneous catalysts in to three sections. The first section described the immobilization of the molybdenum-Schiff base complexes in pores of SBA-15 in two different methodologies depending on the actual structure of the complexes., (i) stepwise formation of the complex by initial covalent anchoring of one of the components and consecutive solid phase synthesis consisting of the condensation of the other components of the salen complex (iii) one-step complex immobilization by covalent binding through the ligand.Based on the first methodology, we report the preparation of ordered mesoporous silica SBA-15 containing a molybdenum...