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Preparation and characterization of a composite biomaterial including starch micro/nano particles loaded chitosan gel
, Article Carbohydrate Polymers ; Volume 174 , 2017 , Pages 633-645 ; 01448617 (ISSN) ; Bagheri, R ; Solouk, A ; Sharif University of Technology
2017
Abstract
Thermosensitive Chitosan hydrogels which can be injected into defects with minimally invasive approach were prepared. Also starch micro/nano particles were synthesized via water-in-oil (W/O) miniemulsion technique. The starch particles were incorporated into the chitosan hydrogel to prepare injectable thermosensitive hydrogel composites. Tube inverting method, compression tests, swelling studies, XRD, SEM, OM, DLS, UV–vis spectroscopy were used for investigations. Results revealed that increasing crosslinker and surfactant contents and stirring rate leads to particle size reduction. Particle size was modeled using design of experiments (DOE) via the response surface method (RSM). Due to...
Injectable in situ forming kartogenin-loaded chitosan hydrogel with tunable rheological properties for cartilage tissue engineering
, Article Colloids and Surfaces B: Biointerfaces ; Volume 192 , 2020 ; Chen, Y ; Wang, D ; Bagheri, R ; Solouk, A ; Wu, H ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Limited regeneration capacity of cartilage can be addressed by tissue engineering approaches including localized delivery of bioactive agents using biomaterials. Although chitosan hydrogels have been considered as appropriate candidates for these purposes, however, their poor mechanical properties limit their real applications. Here, we develop in situ forming chitosan hydrogels with enhanced shear modulus by chemical modification of chitosan using N-(β-maleimidopropyloxy) succinimide ester (BMPS). Moreover, we utilize β-Glycerophosphate (β-GP) in the hydrogels for achieving thermosensitivity. We investigate the effects of BMPS, β-GP and chitosan concentration on rheological and swelling...
Curcumin-Loaded Starch Micro/Nano particles for biomedical application: the effects of preparation parameters on release profile
, Article Starch/Staerke ; Volume 71, Issue 5-6 , 2019 ; 00389056 (ISSN) ; Zahedifar, P ; Bagheri, R ; Solouk, A ; Sharif University of Technology
Wiley-VCH Verlag
2019
Abstract
Although curcumin is highly cytotoxic against cancer cells, its hydrophobicity and fast degradation at physiological pH limit its effective practical application. To prevent such limitations, inexpensive curcumin-loaded starch particles are synthesized in this research. Particles are prepared by water-in-oil (W/O) miniemulsion technique and an adsorption method is used for curcumin loading. Also, encapsulation efficiency (%EE) is improved by using pluronic F-127 in the drug solution. Particles are characterized, swelling studies are performed, and MTT assays against human adipose mesenchymal stem cells (hAMSCs) and MG-63 cells are utilized for investigations. Results indicate that...
A dual functional chondro-inductive chitosan thermogel with high shear modulus and sustained drug release for cartilage tissue engineering
, Article International Journal of Biological Macromolecules ; Volume 205 , 2022 , Pages 638-650 ; 01418130 (ISSN) ; Mehrjou, B ; Wang, D ; Bagheri, R ; Solouk, A ; Chu, P. K ; Wu, H ; Sharif University of Technology
Elsevier B.V
2022
Abstract
We report a chitosan-based nanocomposite thermogel with superior shear modulus resembling that of cartilage and dual pro-chondrogenic and anti-inflammatory functions. Two therapeutic agents, kartogenin (KGN) and diclofenac sodium (DS), are employed to promote chondrogenesis of stem cells and suppress inflammation, respectively. To extend the release time in a controlled manner, KGN is encapsulated in the uniform-sized starch microspheres and DS is loaded into the halloysite nanotubes. Both drug carriers are doped into the maleimide-modified chitosan hydrogel to produce a shear modulus of 167 ± 5 kPa that is comparable to that of articular cartilage (50–250 kPa). Owing to the hydrogel...
Convection heat transfer of MHD fluid flow in the circular cavity with various obstacles: finite element approach
, Article International Journal of Thermofluids ; Volume 20 , 2023 ; 26662027 (ISSN) ; Jalili, P ; Dehghan Afifi, M ; Jalili, B ; Domiri Ganji, D ; Sharif University of Technology
Elsevier B.V
2023
Abstract
In the present research, a study has been conducted on a model to investigate magnetohydrodynamic (MHD) heat and mass transfer phenomena. In the geometry of this model, there is a circular cavity with a variable number of obstacles in each step. At each stage, some obstacles are heated, and its effect on fluid flow and heat transfer is investigated. Solving and developing partial differential equations is done using the finite element method. The effects of Rayleigh and Hartmann numbers on flow lines, isotherms, and equivalent concentrations have been investigated, and the output was displayed as contours and graphs. Finally, the Nusselt diagram is displayed. The main purpose of the present...
Pore-level investigation of heavy oil recovery during water alternating solvent injection process
, Article Transport in Porous Media ; Volume 83, Issue 3 , July , 2010 , Pages 653-666 ; 01693913 (ISSN) ; Farzaneh, S. A ; Kharrat, R ; Ghazanfari, M. H ; Rashtchian, D ; Sharif University of Technology
2010
Abstract
This study concerns with the microscopic and macroscopic fluid distribution and flow behavior during water alternating solvent (WAS) injection process to heavy oil using micromodel generated from thin section of a real rock which has rarely attended in the available literature. In this study, a one-quarter five-spot glass micromodel was deployed to examine the effect of flow media topology on microscopic displacements as well as macroscopic efficiency of WAS process. The micromodel was initially saturated with the heavy oil, and then the hydrocarbon solvent and water were injected alternately into it. The observations confirmed that WAS injection scheme is an effective method for the...
Concentration of Low Grade Zinc Carbonate ore of Anguran Mine by Froth Flotation
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
In this work feasibility of concentrating zinc carbonate ore from Anguran mine by froth flotation process has been studied. Potasium Amyl Xhantate and Oleic Acid have been studied as possible collectors. The initial tests indicate that oleic acid might be a better collector. Experimental were conducted to determined important factors and to optimize the process by careful control of the pulp chemical composition and flotation variables. A concentrate containing 24.9% zinc has been attained. The recovery of zinc in the concentrate is 76.1%.
Some Results and Conjectures on Bounds for Graph Colorings
, M.Sc. Thesis Sharif University of Technology ; Mahmoodian, Ebadollah (Supervisor)
Abstract
There are many ways to color the vertices and edges of graphs, such as, rainbow connection, vertex coloring and dynamic coloring. In this thesis, in Chapter 1 we introduce a new coloring, we consider its relationship with some other colorings and we investigate its computational complexity. In chapter 1, we focus on the proper orientation number. The problem of orienting the edges of a given simple graph so that the maximum indegree of vertices is minimized was introduced in 2004. We show that there is a polynomial time algorithm for determining the proper orientation number of a given 3-regular graph. But it is NP-complete to decide if the proper orientation number of a 4-regular graph is 3...
Concept Drift Detection in Data Streams Using Ensemble Classifiers
, M.Sc. Thesis Sharif University of Technology ; Beigy, Hamid (Supervisor)
Abstract
Concept drift is a challenging problem in the context of data stream processing. As a result of increasing applications of data streams, including network intrusion detection, weather forecasting, and detection of unconventional behavior in financial transactions; numerous studies have been conducted in the field of concept drift detection. In order to solve the problem of concept drift detection, an ideal method should be able to quickly and correctly identify a variety of changes, adapt quickly to new concepts, in the presence of limitations of memory and processing power. In this thesis, a new explicit concept drift detection method based on ensemble classifiers has been proposed for data...
A New Approach Towards Modified Single Drop Microextraction Using Solvents with Densities Higher than Water
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
In the present work, the combination of single drop liquid phase microextraction and gas chromatography-mass detector (GC-MS) was used for determination of pesticides, Clodinafop, Haloxyfop and Fenoxyprop in natural water samples. a novel techniques based on SDME for develop in which solvents with higher density than water was successfully used. this technique could overcome some limitations of conventional SDME such as instability of organic droplet and limited stirrer rate in which result increasing the mass transfer rate and extraction efficiency. Experimental liquid phase microextraction (LPME) conditions, such as extracting solvent, stirring rate, micro drop volume, extraction time, pH...
Studying the Dependence Structure of Tehran Stock Exchange and Over-the-Counter Market by Using Constant and Time-Varying Conditional Copula Functions
, M.Sc. Thesis Sharif University of Technology ; Zamani, Shiva (Supervisor)
Abstract
In this thesis, we study the dependence structure between the Tehran Stock Exchange and over-the-counter market, as the two main Iranian capital market institutions. Several constant and time-varying conditional Copula functions are used to model this dependence structure from October 2009 to August 2014. It is shown that, compared to constant conditional copulas, time-varying conditional copulas, provide a better performance. Analyzing the conditional tail dependence of these indices shows an asymmetric dependence structure. Also, investigating the dynamic conditional correlation and conditional tail dependence, using time-varying conditional copulas, reveals large variations and an...
Upper bounds for the 2-hued chromatic number of graphs in terms of the independence number
, Article Discrete Applied Mathematics ; Volume 160, Issue 15 , 2012 , Pages 2142-2146 ; 0166218X (ISSN) ; Ahadi, A ; Sharif University of Technology
Elsevier
2012
Abstract
A 2-hued coloring of a graph G is a coloring such that, for every vertex v∈V(G) of degree at least 2, the neighbors of v receive at least two colors. The smallest integer k such that G has a 2-hued coloring with k colors is called the 2-hued chromatic number of G, and is denoted by χ2(G). In this paper, we will show that, if G is a regular graph, then χ2(G)-χ(G)≤2log 2(α(G))+3, and, if G is a graph and δ(G)<2, then χ2(G)-χ(G)≤1+4 Δ2δ-1⌉(1+log 2Δ(G)2Δ(G)-δ(G)(α(G))), and in the general case, if G is a graph, then χ2(G)-χ(G)≤2+min α′(G),α(G)+ω(G)2
Experimental Study of a Side Intake in Transonic Speed
, M.Sc. Thesis Sharif University of Technology ; Farahani, Mohammad (Supervisor)
Abstract
This study aims to evaluate aerodynamic coefficients of an airplane with air breathing engine experimentally. In these experiments, an ejector is used to better simulate flying conditions and aerodynamic interferences generated in inlet and exhaust engine. Therefore, at first, an ejector was designed for simultaneous simulation of exit cold flow and inlet flow of engine. All tests were conducted at QRC Trisonic wind tunnel and at Mach number of 0.5 to 0.85, angles of -4 to 6 deg. and for various amounts of pressure ejector and control surfaces angles. Finally, for the Mach number of 0.5, effect of roughness on the aerodynamic coefficients was examined. The results showed that, drag...
Biomechanical Evaluation of the Niosh Equation in Stoop Versus Squat Load-Handling Activities Using a Full-Body Musculoskeletal Model
, M.Sc. Thesis Sharif University of Technology ; Arjmand, Navid (Supervisor)
Abstract
Objective: To assess adequacy of the National Institute for Occupational Safety and Health (NIOSH) Lifting Equation (NLE) in controlling lumbar spine loads below their recommended action limits during load-handling activities in the stoop and squat using a detailed musculoskeletal model,that is, the AnyBody Modeling System.Background: The NIOSH committee employed simplistic biomechanical models for the calculation of the spine compressive loads with no estimates of the shear loads. In addition, NLE does not include the posture of the knee during manual material handling. It is therefore unknown whether the NLE would adequately control lumbar compression and shear loads below their...
Fabrication and Investigation of the Microscopic Structure and Mechanical Properties of Zx00 Magnesium Alloy by Applying the Multi-Directional Forging Process on Extruded and Homogenized Samples
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Magnesium and its alloys have gained significant attention in medical applications due to their good biocompatibility. However, their widespread use has been limited by some inherent drawbacks, such as poor mechanical properties. The ZX00 magnesium alloy has been used in medical applications, including implants, due to its slow degradation rate and good ossification. However, this alloy lacks sufficient strength and ductility. The severe plastic deformation method can create an ultrafine grain structure and improve mechanical properties. In this study, to improve the mechanical properties and create an ultrafine grain structure, the multi-directional forging process was performed on...
Automatic Modulation Recognition of Analog And Digital Modulations
, M.Sc. Thesis Sharif University of Technology ; Behnia, Fereydoon (Supervisor)
Abstract
This thesis investigates various modulation recognition systems both in analogue and digital forms. We are looking for a recognition technique considering practical implementation issues. To recognize the modulation, the career frequency is supposed to be known and a bandpass signal is received. Besides, we investigate some digital Automatic Modulation Recognition (AMR) methods. The techniques based on the features of the signal have less computational complexity compared to Maximum Likelihood (ML) techniques; hence they are more desirable for practical implementation. In this project, analog modulations are implemented using C++ software. For the convenience of users, here, two graphical...
A New Method for Suboptimal Control of a Class of Non-Linear Systems
, M.Sc. Thesis Sharif University of Technology ; Hesaaraki, Mahmoud (Supervisor)
Abstract
In this thesis, a new non-linear control synthsis technique (θ - D) approximation) is discussed. This approach achieves suboptimal solutions to a class of non-linear optimal control problems characterized by a quadratic cost function and a plant model that is a_ne in control. An approximate solution to the Hamilton-Jacobi-Bellman (HJB) equation is sought by adding perturbations to the cost function. By manipulating the perturbation terms both asymptotic stability and suboptimality properties are obtained. The new technique overcomes the large-control-for-large-initial-states problem that occurs in some other Taylor series expansion based methods. Also this method does not require excessive...
In-flight estimation of time-varying aircraft center of gravity position based on kinematics approach
, Article Journal of Aircraft ; Volume 55, Issue 5 , 2018 , Pages 2037-2049 ; 00218669 (ISSN) ; Saghafi, F ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2018
Abstract
In-flight aircraft center of gravity (COG) position estimation is investigated in this study based on the kinematics approach. The Quad-M basics of system identification requirements are carefully investigated for time-invariant and time-varying COG estimation during airdrop maneuver as a case study that contains both conditions. Modeling and simulation of airdrop maneuver are employed to prepare the required maneuver and measurement data for this investigation. The relative-acceleration equation, as a model structure, and parameter modeling of time-varying COG location and acceleration are introduced into the system identification and parameter estimation framework. The Kalman filter method...
Decoupled scalar approach for aircraft angular motion estimation using a gyro-free inertial measurement unit
, Article Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME ; Volume 141, Issue 12 , 2019 ; 00220434 (ISSN) ; Saghafi, F ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2019
Abstract
In-flight aircraft angular motion estimation based on an all-accelerometers inertial measurement unit (IMU) is investigated in this study. The relative acceleration equation as the representative of a rigid-body kinematics is manipulated to present the state and measurement equations of the aircraft dynamics. A decoupled scalar form (DSF) of the system equations, as a free-singularity problem, is derived. Mathematical modeling and simulation of an aircraft dynamics, equipped with an all-accelerometers IMU, are employed to prepare measurement data. Taking into account the modeling of accelerometer error, the measurement data have been simulated as a real condition. Three extended Kalman...
Aircraft mass properties estimation during airdrop maneuver: A nonlinear filtering approach
, Article Journal of Aircraft ; Volume 58, Issue 5 , 2021 , Pages 982-996 ; 00218669 (ISSN) ; Saghafi, F ; Sharif University of Technology
AIAA International
2021
Abstract
Unlike a single-body approach, modeling based on a two-body approach has been employed to prepare the required system dynamic model as a time update equation in the applied filtering technology and measurement data for the estimation process. This more precise mathematical model enabled better understanding about the dynamics of the change in the aircraft mass properties during the airdropping operation. The problem is defined as estimation of the optimal mass properties parameters for the best possible fit of the model output to the real data. The parameter estimation problem is investigated by a nonlinear filtering methodology in two sequential steps. In the first step, the single extended...