Search for: carbon-nanostructures
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    An overview of tight-binding method for two-dimensional carbon structures

    , Article Graphene: Properties, Synthesis and Applications ; 2012 , Pages 1-36 ; 9781614709497 (ISBN) Gharekhanlou, B ; Khorasani, S ; Sharif University of Technology
    Since the advent of graphene, the two-dimension allotrope of carbon, there has been a growing interest in calculation of quantum mechanical properties of this crystal and its derivatives. To this end, the tight-binding model has been in frequent use for a relatively long period of time. This review, presents an in-depth survey on this method as possible to graphene and two of the most important related structures, graphene anti-dot lattice, and graphane. The two latter derivatives of graphene are semiconducting, while graphane is semimetallic. We present band structure and quantum mechanical orbital calculations and justify the results with the density function theory  

    Surface modification of glassy carbon electrode with the functionalized carbon nanotube for ultrasensitive electrochemical detection of risperidone

    , Article Journal of the Iranian Chemical Society ; Volume 15, Issue 7 , July , 2018 , Pages 1485-1494 ; 1735207X (ISSN) Shahrokhian, S ; Hafezi Kahnamoui, M ; Salimian, R ; Sharif University of Technology
    Springer Verlag  2018
    Risperidone (RIS), one of the typical antipsychotics drugs, originally approved to be used for the mental illness treatment, especially schizophrenia, bipolar disorder, autism and major depression. In the present study, different carbon nanostructures including functionalized multi-walled carbon nanotubes (F-MWCNTs), carbon nanoparticles, nanodiamond-graphite and reduced graphene oxide were employed for modification of the surface of glassy carbon electrode (GCE) for ultrasensitive detection of RIS. The most significant increase in the anodic peak current of RIS was observed on F-MWCNTs-modified electrode (compared to the other modified electrodes and bare GCE). The influence of different... 

    Enzymatic biosensing by covalent conjugation of enzymes to 3D-networks of graphene nanosheets on arrays of vertically aligned gold nanorods: application to voltammetric glucose sensing

    , Article Microchimica Acta ; Volume 185, Issue 3 , 2018 ; 00263672 (ISSN) Mazaheri, M ; Simchi, A ; Aashuri, H ; Sharif University of Technology
    Springer-Verlag Wien  2018
    The authors demonstrate efficient direct electron transfer from the enzyme glucose oxidase to vertically aligned gold nanorods with a diameter of ~160 nm and a length of ~2 μm that are covalently linkage to a 3-dimensional network of reduced graphene oxide nanosheets. The assembly can be prepared by a 2-step electrochemical procedure. This hybrid structure holds the enzyme in a favorable position while retaining its functionality that ultimately provides enhanced performance for enzymatic sensing of glucose without utilizing mediators. The nanorod assembly was applied to the voltammetric detection of glucose. Figures of merit include an electrochemical sensitivity of 12 μA·mM−1·cm−2... 

    Preparation and Investigation of the Electrochemical Behavior of Sensors Based on Glassy Carbon Electrode Modified with Various Carbon Nanostructures Decorated by Some of Metal Nanoparticlesfor Determination of Ceftizoxime

    , M.Sc. Thesis Sharif University of Technology Ranjbar, Saba (Author) ; Shahrokhian, Saeed (Supervisor) ; Masoumeh Ghalkhani (Co-Advisor)
    In the recent years, sensors and biosensors attracts much attentions as a suitable devices in analytical chemistry. In this meantime carbon nanostructures and metal nanoparticles act as a good choice owing to their unique properties such as high electrical conductivity andmechanical and chemical stability in modification of the surface of sensors and biosensors. Because of importance of analysis the trace amounts of pharmaceutical and biological compounds, in this studies the surface of glassy carbon electrode was modified with some carbon nanostructures and metal nanoparticles for electrochemical investigation and determination of pharmaceutical and clinical compounds.In the first work, a... 

    Preparation of Nano Fluid from Carbon Nano Structures with High Surface Area in Order to Improve the Heat Transfer Coefficient in Heat Exchangers

    , M.Sc. Thesis Sharif University of Technology Naghash Chimeh, Amir Saleh (Author) ; Sattari, Sorena (Supervisor) ; Rashidi, Alimorad (Co-Advisor)
    In this research convective heat transfer coefficient enhancement of nanofluids prepared from high surface area graphene has been investigated in laminar flow in the developing region. The nanofluid has been prepared from nanoporous graphene with high surface area and with concentration of 0.025 to 0.1 %wt. Deionized water has been used as the base fluid and a type of Ter-Polymer has been utilized as the surfactant. The results indicate that thermal conductivity of nanofluid with concentration of 0.1 %wt remains quite constant, with only %3.8 enhancement, while convective heat transfer coefficient improves significantly, with 34% enhancement. The behavior of this enhancement related to the... 

    Multiscale Nonlinear Finite Element Analysis of Nanostructured Materials Based on Equivalent Continuum Mechanics

    , Ph.D. Dissertation Sharif University of Technology Ghanbari, Jaafar (Author) ; Naghdabadi, Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor)
    Nanostructured materials are a new kind of engineering materials which attracted researchers’ interest because of their interesting mechanical /physical properties, as well as controllable microstructural design ability for desired applications. These new materials are homogeneous at the macroscale but at the microstructural level, may have heterogeneities including common nanostructures. Because of multiscale nature of these materials, new multiscale methods should be developed and used for better understanding the behavior of them. Multiscale methods could be categorized into concurrent and hierarchical methods. In concurrent methods, the domain under study is explicitly divided into... 

    Preparation of Nanocomposites Consisting of Nickel Oxide Nanostructures Grown on Hollow Carbon Nanospheres and Evaluation of their Ability for Electrooxidation of Hydrazine Hydrate

    , M.Sc. Thesis Sharif University of Technology Taghaddosi, Sanaz (Author) ; Shahrokhian Dehkordi, Saeed (Supervisor)
    In the present work, nanocomposites consisting of nickel oxide nanostructures and a hollow carbon substrate were used to modify a glassy carbon electrode's surface for the electrooxidation of hydrazine hydrate. For this purpose, hollow carbon nanospheres were first synthesized using aniline and pyrrole copolymerization process without any template needing. The hollow carbon nanospheres prepared by this method have outstanding features such as high specific surface area and good stability. On the other hand, they did not require toxic and environmentally harmful solvents to remove the template. In this study, after preparing hollow carbon nanospheres as a suitable substrate, different... 

    Study and Preparation of the Modified Nanostructure Carbon Electrode for Capacitive Deionization (CDI) Process

    , Ph.D. Dissertation Sharif University of Technology Talebi, Majid (Author) ; Ahadian, Mohammad Mahdi (Supervisor) ; Shahrokhian, Saeed (Supervisor)
    Nowadays capacitive deionization (CDI) has attracted a lot of attention for water treatment. CDI is an emerging water treatment technology that uses electrophoretic driving forces for desalination of water. During the CDI process, ions are adsorbed onto the surface of electrodes by applying a low voltage electric field (DC<2V). In addition, the regeneration of the electrodes contains desorption of the electrosorbed ions from the surface of the electrodes to the water in the absence of the applied electric field. In the mechanism of CDI, separation and accumulation of ions in the electric field are the main processes and no additional chemicals are required in this technology. Therein,... 

    Multiscale nonlinear constitutive modeling of carbon nanostructures based on interatomic potentials

    , Article Computers, Materials and Continua ; Volume 10, Issue 1 , 2009 , Pages 41-64 ; 15462218 (ISSN) Ghanbari, J ; Naghdabadi, R ; Sharif University of Technology
    Continuum-based modeling of nanostructures is an efficient and suitable method to study the behavior of these structures when the deformation can be considered homogeneous. This paper is concerned about multiscale nonlinear tensorial constitutive modeling of carbon nanostructures based on the interatomic potentials. The proposed constitutive model is a tensorial equation relating the second Piola-Kirchhoff stress tensor to Green-Lagrange strain tensor. For carbon nanotubes, some modifications are made on the planar representative volume element (RVE) to account for the curved atomic structure resulting a non-planar RVE. Using the proposed constitutive model, the elastic behavior of the... 

    Composites of reduced graphene oxide/nickel submicrorods for non-enzymatic electrochemical biosensing: application to amperometric glucose detection

    , Article Journal of the Electrochemical Society ; Volume 167, Issue 8 , 2020 Mohammadzadeh, A ; Mazaheri, M ; Sedighian, A ; Ghanbari, H ; Simchi, A ; Sharif University of Technology
    Institute of Physics Publishing  2020
    For the rapid detection of hyperglycemia in human blood, we adopted a facile and two-step electrochemical procedure to prepare nickel/reduced graphene oxide (rGO) hybrid electrodes in the framework of a three-dimensional (3D) nanostructure. High-density and vertically-aligned nickel submicrorods with an average diameter of 155 ± 15 nm and a length of 7 ± 1 μm (an aspect ratio of about 40-50) were prepared by template-mediated electrochemical deposition techniques. Networks of rGO nanosheets between the rod-shaped arrays were formed by the cathodic electrophoretic deposition method. The synergistic effect of nickel morphology (planar and high-density rod-shaped arrays) and graphene oxide... 

    On the mechanical characteristics of graphene nanosheets: A fully nonlinear modified Morse model

    , Article Nanotechnology ; Volume 31, Issue 11 , 2020 Shoghmand Nazarloo, A ; Ahmadian, M ; Firoozbakhsh, K ; Sharif University of Technology
    Institute of Physics Publishing  2020
    In this paper, the mechanical properties of graphene nanosheets are evaluated based on the nonlinear modified Morse model. The interatomic interactions including stretching and bending of the covalent bonds between carbon atoms, are replaced by nonlinear extensional and torsional spring-like elements. The finite element method is implemented to analyze the model under different loading conditions and linear characteristics of the graphene structure including the Young's modulus, surface modulus, shear modulus and Poisson's ratio are evaluated for various geometries and chirality where these properties are shown to be size and aspect ratio dependent. It is also found that when the dimensions... 

    Chemical Modification of Glassy Carbon Electrode by Carbon Nanostructures/Conductive Polymers Composites and Its Application in The Study of Electrochemical Behaviour and Determination of Salbutamol and Isoprenaline

    , M.Sc. Thesis Sharif University of Technology Panahi, Saba (Author) ; Shahrokhian, Saeed (Supervisor)
    In the first part of thesis, the electropolymerization of pyrrole was performed in the presence of new coccine (NC) as a dopant anion on the surface of the electrode precoated with SWCNT. The modified electrode was used to study the voltammetric response of salbutamol (SAL). The results showed a remarkable increase in the anodic peak current of SAL in comparison to the bare GCE. The surface morphology PPY/CNT/GCE was thoroughly characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV) techniques. Under the optimized analysis conditions, the modified electrode showed two linear dynamic ranges of 0.02 – 0.1 μM and 0.1-10 μM with a detection limit of 6 nM for the... 

    Chemical modification of the electrode surface by composites of Ag Nanoparticle Decorated on Multi Walled Carbon Nanotube; Application to Investigate the Electrochemical behavior and Determination of Risperidone and Isoxsuprine drugs

    , M.Sc. Thesis Sharif University of Technology Hafezi Kahnamoui, Mohammad (Author) ; Shahrokhian, Saeed (Supervisor)
    Nowadays, electrochemical sensors have numerous benefits, including simplicity,low cost, high selectivity and high sensitivity as an efficient and useful tool in various fields such as the environment, disease diagnostics, medical and medical surveillance, and Anti-terrorism security systems have become the focus of attention in the field of analytical measurements. In the meantime, carbon nanostructures and metal nanoparticles have been considered as suitable alternatives in order to improve their surface properties due to their unique electronic properties and mechanical and chemical stability. Since the determination of trace amounts of pharmaceutical and biological compounds is very... 

    Targeted Theranostic Delivery System Based on Liposomes Containing Graphene Quantum Dots and Drug Nanoparticles For Monitoring and Treatment of Breast Cancer

    , Ph.D. Dissertation Sharif University of Technology Ramedani, Arash (Author) ; Simchi, Abdolreza (Supervisor) ; Sabzevari, Omid (Supervisor)
    Theranostic liposomes have recently found a broad range of applications in nanomedicine due to stability, the high solubility of biomacromolecules, bioavailability, efficacy, and low adverse effects. However, the limitations of liposomes concerning the short systemic circulation in the body, limited controllability of the release rate, and the inability of in vivo imaging remain challenging. Herein, the development of novel hybrid ultrasound-activated piezoelectric nanoparticles based on a hybrid liposome nanocarrier composed of poly(vinylidene fluoride‐trifluoroethylene), graphene quantum dots (GQDs), and Silibinin (a hydrophobic drug) is presented. The hybrid nanoparticles are an... 

    Generation of various carbon nanostructures in water using IR/UV laser ablation

    , Article Journal of Physics D: Applied Physics ; Volume 46, Issue 16 , March , 2013 ; 00223727 (ISSN) Mortazavi, S. Z ; Parvin, P ; Reyhani, A ; Mirershadi, S ; Sadighi Bonabi, R ; Sharif University of Technology
    A wide variety of carbon nanostructures were generated by a Q-switched Nd : YAG laser (1064 nm) while mostly nanodiamonds were created by an ArF excimer laser (193 nm) in deionized water. They were characterized by transmission electron microscopy, Raman spectroscopy and x-ray photoelectron spectroscopy. It was found that the IR laser affected the morphology and structure of the nanostructures due to the higher inverse bremsstrahlung absorption rate within the plasma plume with respect to the UV laser. Moreover, laser-induced breakdown spectroscopy was carried out so that the plasma created by the IR laser was more energetic than that generated by the UV laser  

    Dynamic and static fracture analyses of graphene sheets and carbon nanotubes

    , Article Composite Structures ; Volume 94, Issue 8 , 2012 , Pages 2365-2372 ; 02638223 (ISSN) Niaki, S. A ; Mianroodi, J. R ; Sadeghi, M ; Naghdabadi, R ; Sharif University of Technology
    Dynamic and static fracture properties of Graphene Sheets (GSs) and Carbon nanotubes (CNTs) with different sizes are investigated based on an empirical inter-atomic potential function that can simulate nonlinear large deflections of nanostructures. Dynamic fracture of GSs and CNTs are studied based on wave propagation analysis in these nanostructures in a wide range of strain-rates. It is shown that wave propagation velocity is independent from strain-rate while dependent on the nanostructure size and approaches to 2.2×10 4m/s for long GSs. Also, fracture strain shows extensive changes versus strain-rate, which has not been reported before. Fracture stress is determined as 115GPa for GSs and... 

    Graphene nanomesh by ZnO nanorod photocatalysts

    , Article ACS Nano ; Volume 4, Issue 7 , 2010 , Pages 4174-4180 ; 19360851 (ISSN) Akhavan, O ; Sharif University of Technology
    Local photodegradation of graphene oxide sheets at the tip of ZnO nanorods was used to achieve semiconducting graphene nanomeshes. The chemically exfoliated graphene oxide sheets, with a thickness of ∼0.9 nm, were deposited on quartz substrates. Vertically aligned ZnO nanorod arrays with diameters of 140 nm and lengths of <1 μm were grown on a glass substrate by using a hydrothermal method. The graphene oxide sheets were physically attached to the tip of the ZnO nanorods by assembling the sheets on the nanorods. UV-assisted photodegradation of the graphene oxide sheets (with dimension of ∼5 × 5 μm) at a contact place with the ZnO nanorods resulted in graphene nanomeshes with a pore size of... 

    Numerical simulation of salt water passing mechanism through nanoporous single-layer graphene membrane

    , Article Chemical Product and Process Modeling ; Volume 11, Issue 1 , 2016 , Pages 73-76 ; 21946159 (ISSN) Chogani, A ; Moosavi, A ; Rahiminejad, M ; Sharif University of Technology
    Walter de Gruyter GmbH  2016
    In recent years carbon nanotubes and other carbon nanostructures such as graphene sheets have attracted a lot of attention due to their unique mechanical, thermal and electrical properties. These structures can be used in desalination of sea water, removal of hazardous substances from water tanks, gases separation, and so on. The nanoporous single layer graphene membranes are very efficient for desalinating water due to their very low thickness. In this method, water-flow thorough the membrane and salt rejection strongly depend on the applied pressure and size of nanopores that are created in graphene membrane. In this study, the mechanism of passing water and salt ions through nanoporous... 

    Fracture analysis of monolayer graphene sheets with double vacancy defects via MD simulation

    , Article Solid State Communications ; Volume 151, Issue 17 , 2011 , Pages 1141-1146 ; 00381098 (ISSN) Ansari, R ; Motevalli, B ; Montazeri, A ; Ajori, S ; Sharif University of Technology
    Carbon nanostructures such as carbon nanotubes (CNTs) and graphene sheets have attracted great attention due to their exceptionally high strength and elastic strain. These extraordinary mechanical properties, however, can be affected by the presence of defects in their structures. When a material contains multiple defects, it is expected that the stress concentration of them superposes if the separation distances of the defects are low, which causes a more reduction of the strength. On the other hand, it is believed that if the defects are far enough such that their affected areas are distinct, their behavior is similar to a material with single defect. In this article, molecular dynamics... 

    Protein G selects two binding sites for carbon nanotube with dissimilar behavior; a molecular dynamics study

    , Article Journal of Molecular Graphics and Modelling ; Volume 87 , 2019 , Pages 257-267 ; 10933263 (ISSN) Ebrahim Habibi, M. B ; Ghobeh, M ; Aghakhani Mahyari, F ; Rafii Tabar, H ; Sasanpour, P ; Sharif University of Technology
    Elsevier Inc  2019
    Background: Study of nanostructure-protein interaction for development of various types of nano-devices is very essential. Among carbon nanostructures, carbon nanotube (CNT) provides a suitable platform for functionalization by proteins. Previous studies have confirmed that the CNT induces changes in the protein structure. Methods: Molecular dynamics (MD) simulation study was employed to illustrate the changes occurring in the protein G (PGB) in the presence of a CNT. In order to predict the PGB surface patches for the CNT, Autodock tools were utilized. Results: Docking results indicate the presence of two different surface patches with diverse amino acids: the dominant polar residues in the...