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Using Surface Properties of Immiscible Fluids in Capillary Tubes for Identification and Separation of Cancerous Blood Cells
, M.Sc. Thesis Sharif University of Technology ; Ayatollahi, Shahabodin (Supervisor) ; Vossoughi, Manochehr (Supervisor)
Abstract
Cancer has been known as one of the main reasons for disease-related deaths in the last decades. Early diagnosis could significantly reduce the level of fatality chances. Among the known cancer types, lung cancer is one of the most malignant ones. The common diagnosticmethods are expensive and using high-technology methods; therefore, the introduction of simple and cheap methods is very urgent to detect it. In this project, surface and interfacial tension measurement of cancerous and normal lung cells have been investigated as an easy detection technique. Among the common measurement methods, Pendant Drop and Capillary height techniques have been utilized in this research work. The obtained...
Evaluation of Material Properties of Short Carbon Nanotube-Based Composites Using Nonlocal ElasticityTheory
, M.Sc. Thesis Sharif University of Technology ; Naghdabadi, Reza (Supervisor)
Abstract
Classical theory of elasticity, which is founded upon results of mechanical experiments on the large scale materials, has reasonable results in predicting mechanical properties. The basic idea in this theory is that stress at a point of the material is only a function of the local strain and it is independent of the nonlocal strains. Therefore, the size of the material does not play any role in analyzing mechanical behavior of materials using this theory. However, results from experiments and atomic simulations have shown that in nano scale materials, such as carbon nanotubes (CNTs) and their composites, mechanical properties are strongly dependent on the size parameters of these materials....
Experimental Investigation for FINDING a Suitable Additive (Nanoparticle) to Design Required Elastic Cement for Iranian Oil/Gas Wells
, M.Sc. Thesis Sharif University of Technology ; Taghikhani, Vahid (Supervisor) ; Soltanian, Hamid (Supervisor) ; Moghadasi, Jamshid (Supervisor) ; Samsam Sokheiravi, Mohammad (Co-Advisor)
Abstract
Previous studies indicate that increasing cement compressive strength can’t prevent loss of zonal isolation and casing collapse in worse case during well operations or formation loading. Since standard cements with high compressive strength can’t solve these problems, so application of elastic cements with low Young’s modulus and high Poisson’s ratio becomes important. These cements sustain generated stresses during well operations and prevent creation of point loads when formation creep occurs. For this purpose, a new additive was designed in order to improve the cement elasticity and tensile strength. It is a nanoparticle and named EX-RIPI (by Research Institute of Petroleum Industry,...
A three-dimensional micromechanical model of brain white matter with histology-informed probabilistic distribution of axonal fibers
, Article Journal of the Mechanical Behavior of Biomedical Materials ; Volume 88 , 2018 , Pages 288-295 ; 17516161 (ISSN) ; Farahmand, F ; Shamloo, A ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
This paper presents a three-dimensional micromechanical model of brain white matter tissue as a transversely isotropic soft composite described by the generalized Ogden hyperelastic model. The embedded element technique, with corrected stiffness redundancy in large deformations, was used for the embedment of a histology-informed probabilistic distribution of the axonal fibers in the extracellular matrix. The model was linked to a multi-objective, multi-parametric optimization algorithm, using the response surface methodology, for characterization of material properties of the axonal fibers and extracellular matrix in an inverse finite element analysis. The optimum hyperelastic...
Modeling of interaction between a three-fingered surgical grasper and human spleen
, Article Studies in Health Technology and Informatics, 9 February 2011 through 12 February 2011, Newport Beach, CA ; Volume 163 , 2011 , Pages 663-669 ; 09269630 (ISSN) ; 9781607507055 (ISBN) ; Mirbagheri, A ; Asghari, M ; Farahmand, F ; Sharif University of Technology
2011
Abstract
The aim of this study was to develop a more sophisticated model of the spleen tissue and investigate its interactions with a three-fingered laparoscopic grasper. The spleen tissue, modeled as a hyper viscoelastic material, was subjected to external loadings, imposed by rigid grasping jaws. The tissue deformation as well as the sliding occurrence between tissue and jaws was investigated using nonlinear finite element method. Results indicated that a grasping configuration which aimed a sufficiently large piece of spleen with small radius of curvature was more successful for effective grasping. The trends and magnitudes of the tooltissue interaction forces obtained during effective and...
Tissue growth into three-dimensional composite scaffolds with controlled micro-features and nanotopographical surfaces
, Article Journal of Biomedical Materials Research - Part A ; Volume 101, Issue 10 , 2013 , Pages 2796-2807 ; 15493296 (ISSN) ; Simchi, A ; Dunlop, J. W. C ; Fratzl, P ; Bagheri, R ; Vossoughi, M ; Sharif University of Technology
2013
Abstract
Controlling topographic features at all length scales is of great importance for the interaction of cells with tissue regenerative materials. We utilized an indirect three-dimensional printing method to fabricate polymeric scaffolds with pre-defined and controlled external and internal architecture that had an interconnected structure with macro- (400-500 μm) and micro- (∼25 μm) porosity. Polycaprolactone (PCL) was used as model system to study the kinetics of tissue growth within porous scaffolds. The surface of the scaffolds was decorated with TiO2 and bioactive glass (BG) nanoparticles to the better match to nanoarchitecture of extracellular matrix (ECM). Micrometric BG particles were...
Design and simulation of a microfluidic device for acoustic cell separation
, Article Ultrasonics ; Volume 84 , March , 2018 , Pages 234-243 ; 0041624X (ISSN) ; Boodaghi, M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Experimental acoustic cell separation methods have been widely used to perform separation for different types of blood cells. However, numerical simulation of acoustic cell separation has not gained enough attention and needs further investigation since by using numerical methods, it is possible to optimize different parameters involved in the design of an acoustic device and calculate particle trajectories in a simple and low cost manner before spending time and effort for fabricating these devices. In this study, we present a comprehensive finite element-based simulation of acoustic separation of platelets, red blood cells and white blood cells, using standing surface acoustic waves...
Fabrication and evaluation of chitosan/gelatin/PVA hydrogel incorporating honey for wound healing applications: An in vitro, in vivo study
, Article International Journal of Pharmaceutics ; Volume 592 , 2021 ; 03785173 (ISSN) ; Aghababaie, Z ; Afjoul, H ; Jami, M ; Bidgoli, M. R ; Vossoughi, M ; Ramazani, A ; Kamyabhesari, K ; Sharif University of Technology
Elsevier B.V
2021
Abstract
In this study, physically cross-linked hydrogels were developed by freezing-thawing method while different concentrations of honey were included into the hydrogels for accelerated wound healing. The hydrogel was composed of chitosan, polyvinyl alcohol (PVA), and gelatin with the ratio of 2:1:1 (v/v), respectively. Further, the effect of honey concentrations on antibacterial properties, and cell behavior was investigated. In vivo studies, including wound healing mechanism using rat model and histological analysis of section tissue samples were performed. The results illustrated that the incorporation of honey in hydrogels increased the ultimate strain of hydrogels approximately two times,...
Melt electrowriting of PLA, PCL, and composite PLA/PCL scaffolds for tissue engineering application
, Article Scientific Reports ; Volume 12, Issue 1 , 2022 ; 20452322 (ISSN) ; Seifi, S ; Akbari, A ; Mohammadi, K ; Shamloo, A ; Movahhedy, M. R ; Sharif University of Technology
Nature Research
2022
Abstract
Fabrication of well-ordered and bio-mimetic scaffolds is one of the most important research lines in tissue engineering. Different techniques have been utilized to achieve this goal, however, each method has its own disadvantages. Recently, melt electrowriting (MEW) as a technique for fabrication of well-organized scaffolds has attracted the researchers’ attention due to simultaneous use of principles of additive manufacturing and electrohydrodynamic phenomena. In previous research studies, polycaprolactone (PCL) has been mostly used in MEW process. PCL is a biocompatible polymer with characteristics that make it easy to fabricate well-arranged structures using MEW device. However, the...
Investigation of the gas barrier properties of PP/ciay nanocomposite films with EVA as a compatibiliser prepared by the melt intercalation method
, Article Polymer - Plastics Technology and Engineering ; Volume 49, Issue 10 , 2010 , Pages 991-995 ; 03602559 (ISSN) ; Ahmad Ramazani, S. A ; Danaei, M ; Sharif University of Technology
2010
Abstract
In this research, polypropylene (PP) nanocomposite films were prepared by melt intercalation method and their properties have been evaluated. To facilitate the formation of either intercalated or exfoliated nanocomposites, ethylene vinyl acetate copolymer (EVA) was used as a compatibiliser. Morphology of composites was determined by X-ray Diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM analyses confirmed that increasing of EVA content leads to achievement of intercalated nanocomposites. Furthermore, differential scanning calorimetry (DSC) measurement indicated a decrease in crystallinity, melting point and crystallization temperature. Also, permeability tests showed...
Micro resonator nonlinear dynamics considering intrinsic properties
, Article Scientia Iranica ; Volume 16, Issue 2 B , 2009 , Pages 121-129 ; 10263098 (ISSN) ; Tadayon, M. A ; Eftekharian, A. A ; Sharif University of Technology
2009
Abstract
One of the most important phenomena to affect the motion behaviour of Micro Resonators is their thermal dependency. This has recently received the attention of researchers widely. A thermal phenomenon has two main effects, the first is damping, due to internal friction, and the second is softening, due to Young's modulus-temperature relationship. In this research work, some theoretical and experimental reported results are used to make a proper model, including thermal phenomena. Two Lorentzian functions are used to describe the restoring and damping forces caused by thermal phenomena. In order to emphasize the thermal effects, a nonlinear model of the MEMS, considering capacitor...
The effective mechanical properties and the interfacial characterization of CNT reinforced nanocomposites
, Article Proceedings of SPIE - The International Society for Optical Engineering, 9 March 2009 through 11 March 2009, San Diego, CA ; Volume 7294 , 2009 ; 0277786X (ISSN); 9780819475541 (ISBN) ; Naghdabadi, R ; The International Society for Optical Engineering (SPIE) ; Sharif University of Technology
2009
Abstract
A small volume fraction of Carbon Nanotubes (CNTs) added in a polymeric matrix increases significantly the mechanical properties of the polymers. It is experimentally determined from the TEM images of CNT-based nanocomposites that nanotubes don't stand straight in their embedded matrix and they have some curvature in their shape. The load transfer mechanism between CNT and polymer matrix is also one of the most important issues which is not understood explicitly, yet. In this paper a wavy Single Walled Carbon Nanotube (SWCNT) is modeled as inclusion in a polymer matrix and its effective mechanical properties is studied. This model is based on using 3-D Representive Volume Element (RVE) with...
Alginate-based multifunctional films incorporated with sulfur quantum dots for active packaging applications
, Article Colloids and Surfaces B: Biointerfaces ; Volume 215 , 2022 ; 09277765 (ISSN) ; Priyadarshi, R ; Rhim, J. W ; Lotfali, E ; Bagheri, R ; Pircheraghi, G ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Sulfur quantum dots (SQDs) were fabricated using a facile hydrothermal method and used for the preparation of functional food packaging film and compared the properties with other sulfur-based fillers like elemental sulfur (ES) and sulfur nanoparticles (SNP). The SQDs have an average size of 5.3 nm and were very stable in aqueous suspension. Unlike other sulfur-based fillers, the SQD showed high antioxidant, antibacterial and antifungal activity, but no cytotoxicity was found for L929 mouse fibroblasts even after long-term exposure of 48 h. When sulfur-based fillers were added to the alginate film, SQD was more evenly dispersed in the polymer matrix than SNP and ES. The addition of SQD to...
Mechanical properties of graphene cantilever from atomic force microscopy and density functional theory
, Article Nanotechnology ; Volume 21, Issue 18, Article number 185503 , 2010 ; 09574484 ; Iraji Zad, A. (Azam) ; Ahadian, M. M ; Sharif University of Technology
Abstract
We have studied the mechanical properties of a few-layer graphene cantilever (FLGC) using atomic force microscopy (AFM). The mechanical properties of the suspended FLGC over an open hole have been derived from the AFM data. Force displacement curves using the Derjaguin–Müller–Toporov (DMT) and the massless cantilever beam models yield a Young modulus of Ec ~ 37, Ea ~ 0.7 TPa and a Hamakar constant of ~ 3 × 10 − 18 J. The threshold force to shear the FLGC was determined from a breaking force and modeling. In addition, we studied a graphene nanoribbon (GNR), which is a system similar to the FLGC; using density functional theory (DFT). The in-plane Young's modulus for the GNRs were calculated...
Mechanical properties of graphene cantilever from atomic force microscopy and density functional theory
, Article Nanotechnology ; Volume 21, Issue 18 , 2010 ; 09574484 (ISSN) ; Iraji Zad, A ; Ahadian, M. M ; Sharif University of Technology
2010
Abstract
We have studied the mechanical properties of a few-layer graphene cantilever (FLGC) using atomic force microscopy (AFM). The mechanical properties of the suspended FLGC over an open hole have been derived from the AFM data. Force displacement curves using the Derjaguin-Müller-Toporov (DMT) and the massless cantilever beam models yield a Young modulus of Ec ∼ 37, Ea ∼ 0.7TPa and a Hamakar constant of ∼ 3 × 10 -18J. The threshold force to shear the FLGC was determined from a breaking force and modeling. In addition, we studied a graphene nanoribbon (GNR), which is a system similar to the FLGC; using density functional theory (DFT). The in-plane Young's modulus for the GNRs were calculated from...
Mechanical properties of ester- and ether-DPhPC bilayers: A molecular dynamics study
, Article Journal of the Mechanical Behavior of Biomedical Materials ; Volume 117 , 2021 ; 17516161 (ISSN) ; Jamali, Y ; Tajkhorshid, E ; Bavi, O ; Pishkenari, H. N ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In addition to its biological importance, DPhPC lipid bilayers are widely used in droplet bilayers, study of integral membrane proteins, drug delivery systems as well as patch-clamp electrophysiology of ion channels, yet their mechanical properties are not fully measured. Herein, we examined the effect of the ether linkage on the mechanical properties of ester- and ether-DPhPC lipid bilayers using all-atom molecular dynamics simulation. The values of area per lipid, thickness, intrinsic lateral pressure profile, order parameter, and elasticity moduli were estimated using various computational frameworks and were compared with available experimental values. Overall, a good agreement was...
Acoustic resonance scattering from a multilayered cylindrical shell with imperfect bonding
, Article Ultrasonics ; Volume 49, Issue 8 , 2009 , Pages 682-695 ; 0041624X (ISSN) ; Hasheminejad, S. M ; Sharif University of Technology
Abstract
The method of wave function expansion is adopted to study the three dimensional scattering of a time-harmonic plane progressive sound field obliquely incident upon a multi-layered hollow cylinder with interlaminar bonding imperfection. For the generality of solution, each layer is assumed to be cylindrically orthotropic. An approximate laminate model in the context of the modal state equations with variable coefficients along with the classical T-matrix solution technique is set up for each layer to solve for the unknown modal scattering and transmission coefficients. A linear spring model is used to describe the interlaminar adhesive bonding whose effects are incorporated into the global...
A meta-model analysis of a finite element simulation for defining poroelastic properties of intervertebral discs
, Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 227, Issue 6 , 2013 , Pages 672-682 ; 09544119 (ISSN) ; Hsu, Y. C ; Haghpanahi, M ; Parnianpour, M ; Wang, J. L ; Sharif University of Technology
2013
Abstract
Finite element analysis is an effective tool to evaluate the material properties of living tissue. For an interactive optimization procedure, the finite element analysis usually needs many simulations to reach a reasonable solution. The metamodel analysis of finite element simulation can be used to reduce the computation of a structure with complex geometry or a material with composite constitutive equations. The intervertebral disc is a complex, heterogeneous, and hydrated porous structure. A poroelastic finite element model can be used to observe the fluid transferring, pressure deviation, and other properties within the disc. Defining reasonable poroelastic material properties of the...
Dynamic responses of intervertebral disc during static creep and dynamic cyclic loading: A parametric Poroelastic finite element analysis
, Article Biomedical Engineering - Applications, Basis and Communications ; Volume 25, Issue 1 , 2013 ; 10162372 (ISSN) ; Haghpanahi, M ; Parnianpour, M ; Wang, J. L ; Sharif University of Technology
2013
Abstract
Low back pain is a common reason for activity limitation in people younger than 45 years old, and was proved to be associated with heavy physical works, repetitive lifting, impact, stationary work postures and vibrations. The study of load transferring and the loading condition encountered in spinal column can be simulated by finite element models. The intervertebral disc is a structure composed of a porous material. Many physical models were developed to simulate this phenomenon. The confounding effects of poroelastic properties and loading conditions on disc mechanical responses are, nevertheless, not cleared yet. The objective of this study was to develop an axisymmetric poroelastic...
Determination of surface properties and elastic constants of FCC metals: A comparison among different EAM potentials in thin film and bulk scale
, Article Materials Research Express ; Volume 6, Issue 1 , 2019 ; 20531591 (ISSN) ; Yousefi, F. S ; Taghibakhshi, A ; Sharif University of Technology
Institute of Physics Publishing
2019
Abstract
Three independent elastic constants C 11, C 12, and C 44 were calculated and compared using available potentials of eight different metals with FCC crystal structure; Gold, Silver, Copper, Nickel, Platinum, Palladium, Aluminum and Lead. In order to calculate the elastic constants, the second derivative of the energy density of each system was calculated with respect to different directions of strains. Each set of the elastic constants of the metals in bulk scale was compared with experimental results, and the average relative error was for each was calculated and compared with other available potentials. Then, using the Voigt-Reuss-Hill method, approximated values for Young and shear moduli...