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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,...
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...
Two-dimensional porous graphitic carbon nitride C6N7 monolayer: first-principles calculations
, Article Applied Physics Letters ; Volume 119, Issue 14 , 2021 ; 00036951 (ISSN) ; Faraji, M ; Fadlallah, M. M ; Abdolhosseini Sarsari, I ; Jappor, H. R ; Fazeli, S ; Ghergherehchi, M ; Sharif University of Technology
American Institute of Physics Inc
2021
Abstract
The fabrication of the C6N7 monolayer [Zhao et al., Sci. Bull. 66, 1764 (2021)] motivated us to discover the optical, structural, mechanical, and electronic properties of the C6N7 monolayer by employing the density functional theory (DFT) method. We find that the shear modulus and Young's modulus of the C6N7 monolayer are smaller than the relevant values of graphene. However, Poisson's ratio is more significant than that of graphene. Applying the PBE (HSE06) functional bandgap of the C6N7 monolayer is 1.2 (1.97) eV, and the electronic dispersion is almost isotropic around the Γ point. C6N7 is more active in the ultraviolet region as compared to the visible light region. This study provides...
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...
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...
Rheology of interfacial layers
, Article Current Opinion in Colloid and Interface Science ; Vol. 19, issue. 6 , 2014 , pp. 514-519 ; ISSN: 13590294 ; Lotfi, M ; Kragel, J ; Javadi, A ; Bastani, D ; Miller, R ; Sharif University of Technology
Abstract
Dilational and shear viscoelasticities are important properties of interfacial layers. These quantities are particularly relevant in all systems which contain a huge internal interfacial area such as foams and emulsions. Therefore, also the 3D rheological behavior of foams or emulsions studied by respective methods is superimposed by the 2D interfacial rheology.We report on recent developments in dilational and shear rheology from an experimental point of view as well as discuss the state of the art of the underlying theories. Examples of most relevant experiments are also presented and discussed. Although not yet extensively investigated, the links between bulk rheology of foams and...
Proposing a new model to approximate the elasticity modulus of granite rock samples based on laboratory tests results
, Article Bulletin of Engineering Geology and the Environment ; Volume 78, Issue 3 , 2019 , Pages 1527-1536 ; 14359529 (ISSN) ; Esfandi Sarafraz, M ; Hasanipanah, M ; Mojtahedi, S. F. F ; Tahir, M. M ; Sharif University of Technology
Springer Verlag
2019
Abstract
An accurate examination of deformability of rock samples in response to any change in stresses is deeply dependent on the reliable determination of properties of the rock as analysis inputs. Although Young’s modulus (E) can provide valuable characteristics of the rock material deformation, the direct determination of E is considered a time-consuming and complicated analysis. The present study is aimed to introduce a new hybrid intelligent model to predict the E of granitic rock samples. Hence, a series of granitic block samples were collected from the face of a water transfer tunnel excavated in Malaysia and transferred to laboratory to conduct rock index tests for E prediction. Rock index...
Preparation and characterization of starch-based composite films reinforced by cellulose nanofibers
, Article International Journal of Biological Macromolecules ; Volume 116 , 2018 , Pages 272-280 ; 01418130 (ISSN) ; Keley, M ; Biazar, E ; Sharif University of Technology
Elsevier B.V
2018
Abstract
The current study deals with the preparation and characterization of polysaccharide-based biocomposite films acquired by the incorporation of cellulose nanofiber within glycerol plasticized matrix formed by starch. The application of starch-based films is limited due to highly hydrophilic nature and poor mechanical properties. These problems are solved by forming a nanocomposite of thermoplastic starch (TPS) as matrix and cellulose nanofiber (CNF) as reinforcement. CNF is successfully prepared from short henequen fibers which consist of almost 60% cellulose by a chemo-mechanical process. TPS/CNF composite films are prepared by the polymer solution casting method, and their characterizations...
Preparation and characterization of multi-walled carbon nanotube/hydroxyapatite nanocomposite film dip coated on Ti-6Al-4V by sol-gel method for biomedical applications: An in vitro study
, Article Materials Science and Engineering C ; Volume 33, Issue 4 , 2013 , Pages 2002-2010 ; 09284931 (ISSN) ; Hooshmand, T ; Mohammadi, M ; Najafi, F ; Sharif University of Technology
2013
Abstract
In the present research, the introduction of multi-walled carbon nanotubes (MWCNTs) into the hydroxyapatite (HA) matrix and dip coating of nanocomposite on titanium alloy (Ti-6Al-4V) plate was conducted in order to improve the performance of the HA-coated implant via the sol-gel method. The structural characterization and electron microscopy results confirmed well crystallized HA-MWCNT coating and homogenous dispersion of carbon nanotubes in the ceramic matrix at temperatures as low as 500 C. The evaluation of the mechanical properties of HA and HA/MWCNT composite coatings with different weight percentages of MWCNTs showed that the addition of low concentrations of MWCNTs (0.5 and 1 wt.%)...
Preparation and characteristics of epoxy/clay/B4C nanocomposite at high concentration of boron carbide for neutron shielding application
, Article Radiation Physics and Chemistry ; Volume 141 , 2017 , Pages 223-228 ; 0969806X (ISSN) ; Ahmadi, S. J ; Outokesh, M ; Adeli, R ; Mohammadi, A ; Sharif University of Technology
Abstract
In this research, the characteristics of the prepared samples in epoxy matrix by means of X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), as well as scanning electron microscope (SEM) are evaluated. Meanwhile, the obtained mechanical properties of the specimen are investigated. Thermogravimetric analysis (TGA) is also employed to evaluate the thermal degradation of manufactured nanocomposites. The thermal neutron absorption properties of nanocomposites containing 3 wt% of montmorillonite nanoclay (closite30B) have been studied experimentally, using an Am-Be point source. Mechanical tests reveal that the higher B4C concentrations, the more tensile strengths, but lower...
Porous shape memory dental implant by reactive sintering of TiH2–Ni-Urea mixture
, Article Materials Science and Engineering C ; Volume 107 , 2020 ; Sadrnezhaad, S .K ; Hosseini, S. A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
We produced bifurcated bone-like shape memory implant (BL-SMI) with desirable tooth-root fixation capability by compact-sintering of TiH2–Ni-urea mixture. The primary constituents of the porous product were Ni and Ti. We could adjust the pores' shape, size, and interconnectivity for favorite bone ingrowth by using urea as a space holder. Without urea, we obtained an average porosity of 0.30, and a mean void size of 100 μm. With 70 vol % urea, we got 62% interconnected pores of 400 μm average size. Aging allowed us to tune the austenite-martensite transformation temperatures towards the needed body tissue arouse. Differential scanning calorimetry measured the transformation temperatures....
Permeability mapping of gelatin methacryloyl hydrogels
, Article Acta Biomaterialia ; Volume 77 , 2018 , Pages 38-47 ; 17427061 (ISSN) ; Goodarzi Hosseinabadi, H ; Cecen, B ; Hassan, S ; Shrike Zhang, Y ; Sharif University of Technology
Abstract
We report the development of an efficient, customized spherical indentation-based testing method to systematically estimate the hydraulic permeability of gelatin methacryloyl (GelMA) hydrogels fabricated in a wide range of mass concentrations and photocrosslinking conditions. Numerical simulations and Biot's theory of poroelasticity were implemented to calibrate our experimental data. We correlated elastic moduli and permeability coefficients with different GelMA concentrations and crosslinking densities. Our model could also predict drug release rates from the GelMA hydrogels and diffusion of biomolecules into the three-dimensional GelMA hydrogels. The results potentially provide a design...
Nanomechanical properties of MscL α helices: A steered molecular dynamics study
, Article Channels ; Volume 11, Issue 3 , 2017 , Pages 209-223 ; 19336950 (ISSN) ; Bavi, O ; Vossoughi, M ; Naghdabadi, R ; Hill, A. P ; Martinac, B ; Jamali, Y ; Sharif University of Technology
Taylor and Francis Inc
2017
Abstract
Gating of mechanosensitive (MS) channels is driven by a hierarchical cascade of movements and deformations of transmembrane helices in response to bilayer tension. Determining the intrinsic mechanical properties of the individual transmembrane helices is therefore central to understanding the intricacies of the gating mechanism of MS channels. We used a constant-force steered molecular dynamics (SMD) approach to perform unidirectional pulling tests on all the helices of MscL in M. tuberculosis and E. coli homologs. Using this method, we could overcome the issues encountered with the commonly used constant-velocity SMD simulations, such as low mechanical stability of the helix during...
Modeling vibrational behavior of silicon nanowires using accelerated molecular dynamics simulations
, Article Scientia Iranica ; Volume 27, Issue 2 , 2021 , Pages 819-827 ; 10263098 (ISSN) ; Delafrouz, P ; Sharif University of Technology
Sharif University of Technology
2021
Abstract
The classical methods utilized for modeling nano-scale systems are not practical because of the enlarged surface e ects that appear at small dimensions. Contrarily, implementing more accurate methods is followed by prolonged computations as these methods are highly dependent on quantum and atomistic models, and they can be employed for very small sizes in brief time periods. In order to speed up the Molecular Dynamics (MD) simulations of the silicon structures, Coarse-Graining (CG) models are put forward in this research. The procedure involves establishing a map between the main structure's atoms and the beads comprising the CG model and modifying the parameters of the system so that the...
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...
Model-based needle control in prostate percutaneous procedures
, Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 227, Issue 1 , 2013 , Pages 58-71 ; 09544119 (ISSN) ; Jahed, M ; Sharif University of Technology
2013
Abstract
In percutaneous applications, needle insertion into soft tissue is considered as a challenging procedure, and hence, it has been the subject of many recent studies. This study considers a model-based dynamics equation to evaluate the needle movement through prostate soft tissue. The proposed model estimates the applied force to the needle using the tissue deformation data and finite element model of the tissue. To address the role of mechanical properties of the soft tissue, an inverse dynamics control method based on sliding mode approach is used to demonstrate system performance in the presence of uncertainties. Furthermore, to deal with inaccurate estimation of mechanical parameters of...
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...
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...
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...