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nanotubes
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Novel structures for carbon nanotube field effect transistors
, Article International Journal of Modern Physics B ; Volume 23, Issue 19 , 2009 , Pages 3669-3678 ; 02179792 (ISSN) ; Hosseini, S. E ; Sharif University of Technology
2009
Abstract
A carbon nanotube field effect transistor (CNTFET) has been studied based on the SchrödingerPoisson formalism. To improve the saturation range in the output characteristics, new structures for CNTFETs are proposed. These structures are simulated and compared with the conventional structure. Simulations show that these structures have a wider output saturation range. With this, larger drain-source voltage (Vds) can be used, which results in higher output power. In the digital circuits, higher Vds increases noise immunity. © 2009 World Scientific Publishing Company
Synthesis of anodized TIO2 nanotube arrays as ion sieve for lithium extraction
, Article ChemistrySelect ; Volume 5, Issue 33 , 2020 , Pages 10339-10345 ; Taghvaei, E ; Askari, M ; Sharif University of Technology
Wiley-Blackwell
2020
Abstract
Titanium type lithium ion-sieve nanotubes synthesized by the hydrothermal method were extensively explored over recent years due to its promising properties. However, on account of nanotubes′ tangled structure impeding the lithium adsorption in the interior nanotube walls, unalterable dimensions of the synthesized nanotubes, and a long period of annealing, the anodizing technique was proposed. It is shown that lithium uptake and adsorption capacity is improved because of easier mass transfer during the ion exchange process. This work focuses on a novel anodizing method for nanotube ion-sieve synthesis. The optimum anodizing condition was discovered by altering anodizing voltage, time, and...
Simultaneous voltammetric determination of uric acid and ascorbic acid using a carbon-paste electrode modified with multi-walled carbon nanotubes/nafion and cobalt(II)-nitrosalophen
, Article Electroanalysis ; Volume 19, Issue 21 , 2007 , Pages 2234-2242 ; 10400397 (ISSN) ; Zare Mehrjardi, H. R ; Sharif University of Technology
2007
Abstract
A composition of multiwalled carbon nanotube (MWCNT), Nafion and cobalt(II)-5-nitrosalophen (CoNSal) is applied for the modification of carbon-paste electrode (CPE). The pretreated MWCNT is well dispersed in the alcoholic solution of Nafion under the ultrasonic agitation, and the resulted suspension is used as modifier (with 10% w/w) in the matrix of the paste electrode. The prepared electrode further modified by addition of 3 wt% of CoNSal. The resulted modified electrode is used as a sensitive voltammetric sensor for simultaneous determination of uric acid (UA) and ascorbic acid (AA). The electrode showed efficient electrocatalytic activity in lowering the anodic overpotentials and...
The effect of oxidation of macroporous silicon on carbon nanotubes growth by TCVD method
, Article Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry ; Volume 37, Issue 6 , 2007 , Pages 489-492 ; 15533174 (ISSN) ; Iraji zad, A ; Taghavi, N. S ; Reyhani, A ; Sharif University of Technology
2007
Abstract
Carbon nanotubes (CNTs) were grown on deposited Ni on macroporous silicon by thermal chemical vapor deposition (TCVD) method using CH4 as the reaction gas. Macroporous silicon was fabricated by electrochemical etching of P-type silicon in organic electrolytes. The effect of oxidation of porous silicon (PS) on growth rate, morphology and structure of CNTs has been studied. The SEM micrographs and Raman spectra indicated that the nanotubes grown on the oxidized PS are more homogeneous and regular than those grown on the pristine PS and growth rate of CNTs grown on oxidized PS higher than those grown on pristine PS. In addition, the CNTs grown on the non-oxidized PS have different morphology...
Morphology control in oxygen-rich nanotubular titania for enzyme-free glucose detection
, Article Surfaces and Interfaces ; 2021 ; 24680230 (ISSN) ; Naseri, N ; Sharif University of Technology
Elsevier B.V
2021
Abstract
The necessity of research in food and nutrition and the emergence of diabetes mellitus call for fast and efficient glucose detection. Here, series of highly sensitive non-enzymatic photoelectrochemical glucose sensor based on engineered titanium dioxide nanotube arrays has been synthesized using a simple electrochemical approach to tune nanotubes morphology in a way that the highest sensitivity factor (525.5 µAmM−1cm−2) and saturation concentrations (0.18 mM) achieved in the photoelectrochemical sensor. The formation of oxygen-rich titanium oxide was confirmed by several techniques. Dependent on the growth condition, nanotube length changed from 1.9 to 8.4 µm while their inner diameter...
Carbon nanotubes composite membrane for water desalination
, Article Advances in Science, Technology and Innovation ; 2021 , Pages 163-184 ; 25228714 (ISSN) ; Khadir, A ; Taghipour, M ; Sharif University of Technology
Springer Nature
2021
Abstract
The demand for freshwater has enormously risen the water stress in various parts of the globe. Accessibility of clean water is crucial for sustainable development involving socioeconomic and environmental promotion. Considering the fact that 96.5% of all Earth’s water is related to seawater, desalination (producing clean potable water from sea or saline water) can be considered as a leading solution to fulfill water scarcity problem. Among various advanced and conventional techniques, carbon nanotube (CNT) membrane has become an attractive alternate for most of water treatment methods owing supreme features such as easy operationality, low energy and expense requirement, high water...
Electronic properties of magnetically doped nanotubes
, Article Bulletin of Materials Science ; Volume 26, Issue 1 , 2003 , Pages 105-107 ; 02504707 (ISSN) ; Chen, Z ; Kawazoe, Y ; Sharif University of Technology
Indian Academy of Sciences
2003
Abstract
Effect of doping of carbon nanotubes by magnetic transition metal atoms has been considered in this paper. In the case of semiconducting tubes, it was found that the system has zero magnetization, whereas in metallic tubes the valence electrons of the tube screen the magnetization of the dopants: the coupling to the tube is usually antiferromagnetic (except for Cr)
Effect of zirconia nanotube coating on the hydrophilicity and mechanochemical behavior of zirconium for biomedical applications
, Article Surfaces and Interfaces ; Volume 28 , 2022 ; 24680230 (ISSN) ; Sarraf, M ; Musharavati, F ; Jaber, F ; Wang, J. I ; Hosseini, H. R. M ; Bae, S ; Chowdhury, M ; So, H ; Sukiman, N. L ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Zirconium has attracted considerable attention in the biomedical field owing to its biocompatibility and desirable tribological and mechanical properties. In this study, we anodized pure zirconium in an ammonium fluoride and ethylene glycol electrolyte, which produced a coating of ZrO2 nanotubes (NTs). The ZrO2 coated samples were annealed at different temperatures, and the morphology and structure of the coated substrates were studied using XPS, SEM, TEM, EDS, and SAED. The micro/nanomechanical properties and corrosion resistance of the samples were evaluated. Wear tests performed on bare and coated substrates revealed that the coated samples annealed at 400 °C had a significantly lower...
Morphology control in oxygen-rich nanotubular titania for enzyme-free glucose detection
, Article Surfaces and Interfaces ; Volume 28 , 2022 ; 24680230 (ISSN) ; Naseri, N ; Sharif University of Technology
Elsevier B.V
2022
Abstract
The necessity of research in food and nutrition and the emergence of diabetes mellitus call for fast and efficient glucose detection. Here, series of highly sensitive non-enzymatic photoelectrochemical glucose sensor based on engineered titanium dioxide nanotube arrays has been synthesized using a simple electrochemical approach to tune nanotubes morphology in a way that the highest sensitivity factor (525.5 µAmM−1cm−2) and saturation concentrations (0.18 mM) achieved in the photoelectrochemical sensor. The formation of oxygen-rich titanium oxide was confirmed by several techniques. Dependent on the growth condition, nanotube length changed from 1.9 to 8.4 µm while their inner diameter...
Molecular dynamics of single wall carbon nanotube growth on nickel surface
, Article Computational Materials Science ; Volume 36, Issue 1-2 , 2006 , Pages 117-120 ; 09270256 (ISSN) ; Gorjizadeh, N ; Nasrollahi, Z ; Sharif University of Technology
2006
Abstract
Growth mechanism of a single wall carbon nanotube on the surface of a nickel nanoparticle in the CVD method has been investigated by classical molecular dynamics method. Using first principles methods, we have first constructed a classical potential to describe the interaction between a carbon atom and the nickel surface. The important ingredient in this potential is its coordination number dependence, which also provides the key to the growth mechanism of the nanotube. From the simulations, it is proposed that the growth of an armchair nanotube takes place via attachment of dimers to its end which is in contact with the nickel surface. The effect of nickel nanoparticle's radius on the...
Dispersive micro-solid phase extraction using magnetic nanoparticle modified multi-walled carbon nanotubes coupled with surfactant-enhanced spectrofluorimetry for sensitive determination of lomefloxacin and ofloxacin from biological samples
, Article Materials Science and Engineering C ; Volume 60 , 2016 , Pages 30-36 ; 09284931 (ISSN) ; Pourghazi, K ; Hajjaran, S ; Sharif University of Technology
Elsevier Ltd
Abstract
A dispersive micro-solid-phase extraction (D-μ-SPE) procedure coupled with surfactant-enhanced spectrofluorimetric detection was developed for determination of ofloxacin and lomefloxacin from biological and environmental samples. The D-μ-SPE procedure was performed using magnetic Fe3O4 nanoparticle grafted multi-walled carbon nanotube as an efficient adsorbent. The main factors affecting the signal enhancement (including surfactant concentration and pH) and extraction efficiency (including pH, extraction time, sample volume, amount of magnetic adsorbent, and desorption conditions) were investigated in detail. Under the optimized conditions, the calibration curves were linear (R2 0.9995) over...
Improved efficiency in front-side illuminated dye sensitized solar cells based on free-standing one-dimensional TiO2 nanotube array electrodes
, Article Solar Energy ; Volume 184 , 2019 , Pages 115-126 ; 0038092X (ISSN) ; Khameneh Asl, S ; Mohammadpour, R ; Khameneh Asl, S ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Although morphological disorder of nanotube structure is further down than the nanoparticular electrode, its density of traps are the hindering effects in the charge transport. In this study, crack-free TiO2 nanotube membranes, which obtained through a re-anodizing process, are fixed on transparent fluorine–tin-oxide glass by applying a few drops of Titanium Isopropoxide without needing the TiO2 powder paste. Front-side illuminated dye sensitized solar cells fabricated by undoped, N-doped and blue TiO2 nanotube membranes are investigated. The electrical characteristics of TiO2 nanotube based dye sensitized solar cells are followed by theoretical analysis using simple one-diode model....
The effects of geometrical parameters on force distributions and mechanics of carbon nanotubes: A critical study
, Article Communications in Nonlinear Science and Numerical Simulation ; Volume 14, Issue 12 , 2009 , Pages 4246-4263 ; 10075704 (ISSN) ; Motevalli, B ; Sharif University of Technology
Abstract
In this paper, using the continuum approximation together with Lennard-Jones potential, a new semi-analytical expression is given to evaluate the van der Waals interaction between two single-walled carbon nanotubes. Based on this expression, two new formulations are also proposed to model multi-walled carbon nanotubes. In the first one, the interactions between each pair of shells from the inner and outer tubes are summed up over all of the pairs, whereas in the second formulation, a set of correction factors are applied to convert the results of double-walled carbon nanotubes to the correlated multi-walled ones. With respect to the present formulations, extensive studies on the variations...
Band-gap narrowing and electrochemical properties in N-doped and reduced anodic TiO2 nanotube arrays
, Article Electrochimica Acta ; Volume 270 , 2018 , Pages 245-255 ; 00134686 (ISSN) ; Khameneh Asl, S ; Mohammadpour, R ; Khameneh Asl, S ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Electrochemical activity of TiO2 nanotube arrays (NTAs) is restricted by a wide band gap of TiO2. To overcome this restriction, we considered systematic research on two effective methods of doping of TiO2 NTAs such as the N-doping and electrochemical reductive doping and predicting the proper application of them. Band gap narrowing was occurred from 3.16 eV for undoped TiO2 NTAs to 2.9 and 2.7 eV at N-doped and self-doped TiO2 ones respectively. The electrochemical responses of the TiO2 NTAs before and after doping were examined by cyclic Voltammetry (CV) curve. To understand the electrochemical behavior of the undoped and doped TiO2 NTAs, electrochemical impedance spectroscopy (EIS) was...
Carbon nanotubes-graft-polyglycerol: biocompatible hybrid materials for nanomedicine
, Article Polymer ; Volume 50, Issue 15 , 2009 , Pages 3528-3536 ; 00323861 (ISSN) ; Mirab, N ; Shafiee Alavidjeh, M ; Sobhani, Z ; Atyabi, F ; Sharif University of Technology
2009
Abstract
New biocompatible and water soluble hybrid materials containing multi-wall carbon nanotubes (MWCNTs) as core and hyperbranched polyglycerol (PG) as shell were synthesized successfully. In this work, pristine MWCNTs were opened and functionalized through treatment with acid and polyglycerol was covalently grafted onto their surface by the "grafting from" approach based on in-situ ring-opening polymerization of glycidol. Some short-term In vitro cytotoxicity and hemocompatibility tests were conducted on HT1080 cell line (human Fibrosarcoma), because this epithelial cell line can be one of the first route of entry of the exogenous materials to the vascular system and therefore subsequent...
Multiwalled carbon nanotube-polyelectrolyte gels: Preparation and swelling behavior for organic solvents
, Article Solid State Ionics ; Vol. 257 , 2014 , pp. 32-37 ; ISSN: 01672738 ; Doulabi, M ; Sharif University of Technology
Abstract
In this article, we report the first multiwalled carbon nanotube-polyelectrolyte gel containing vinylimidazolium-typed ionic liquid monomer as an absorbent of less-polar or nonpolar organic solvents. To prepare such MWCNT-polyelectrolyte gel, the modified MWCNTs with polymerizable vinyl groups on their surfaces were prepared and then underwent copolymerizations with dodecyl methacrylate and vinylimidazolium in the presence of AIBN as initiator, yielding a cross-linked polyelectrolyte. In order to estimate the compatibility between the solvents and the polymers, a series of vinylimidazolium-typed ionic liquid monomers ([Cnvim][X]) with different alkyl tail length (C6, C10 and C12) and counter...
Temperature dependence and the effect of charge configuration on water permeation through modified carbon nanotubes: A simulation study
, Article Fluid Phase Equilibria ; Volume 363 , 15 February , 2014 , Pages 282-289 ; ISSN: 03783812 ; Parsafar, G ; Sharif University of Technology
Abstract
We have investigated the water permeation through carbon nanotube (CNT) membranes as a model of peptide nanotube channels (PNCs). The effect of different charge configured CNTs which tailored based on some artificial ion channels on the water permeation through the channels have been studied. In addition, the temperature dependence of the permeation has been investigated. We have found that there is a jump in the permeation which is somehow related to the characteristics of each channel and the temperature of this permeation jump changes according to the channel configuration. Our investigation on the channels shows that the temperature at which the permeation jump occurs is related to the...
Modification of well-aligned carbon nanotubes with dihexadecyl hydrogen phosphate: Application to highly sensitive nanomolar detection of simvastatin
, Article Journal of Applied Electrochemistry ; Volume 44, Issue 2 , February , 2014 , Pages 263-277 ; ISSN: 0021891X ; Afshar, A ; Dolati, A ; Ghalkhani, M ; Sharif University of Technology
Abstract
The first usage of dihexadecyl hydrogen phosphate (DHP)-modified highly oriented multi-walled carbon nanotube (MWCNTs) forests in a sensor configuration was developed to investigate the electrochemical oxidation and determination of simvastatin (SV) in pharmaceutical dosage forms. Synthesis of well-aligned MWCNTs on a conductive Ta substrate by catalytic vapor deposition technique using a common chemical, ethylenediamine, and without being plasma-aided was reported. The electrochemical behavior and oxidation of SV at the aligned MWCNTs/DHP/Ta electrode were discussed in detail through cyclic voltammetry and differential pulse voltammetry. This modified electrode showed considerably higher...
Cure kinetic and network structure of NR/SBR composites reinforced by multiwalled carbon nanotube and carbon blacks
, Article Thermochimica Acta ; Volume 566 , 2013 , Pages 238-248 ; 00406031 (ISSN) ; Shojaei, A ; Sharif University of Technology
2013
Abstract
Low structure carbon black (CBN330), conductive high structure carbon black (CBXE2B) and carboxylated multiwalled carbon nanotube (MWCNT) were loaded into the blend of natural rubber (NR) and styrene butadiene rubber (SBR) at different contents up to 10 phr. Kraus plots showed that all the reinforcements interact with NR/SBR blend appropriately. However, the CBXE2B whose interfacial area is the highest showed greatest value of Kraus interaction parameter. Flory-Rhener model and effective torque value revealed that all of the reinforcements enhanced the crosslink density, among them CBXE2B showed the highest impact and MWCNT placed in the second rank. It was also shown that the cure kinetic...
Semi-conducting carbon nanotube as variable capacitor
, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 54 , 2013 , Pages 9-14 ; 13869477 (ISSN) ; Naghdabadi, R ; Sharif University of Technology
2013
Abstract
This paper proposes a novel, one-part, variable capacitor, using semi-conducting carbon nanotube (CNT). This variable capacitor works based on the change in the electronic structure of CNTs under applied voltage and deformations. Positive and negative charges are stored at both ends of a non-zero band gap nanotube which works as metallic electrodes in parallel plate capacitors. Also the neutral strip in the middle acts as the dielectric part of a conventional capacitor under the influence of an external electric field. Mechanical strains on carbon nanotube change its band gap energy and thus the length of neutral strip and charged regions. The lengths of these parts are primarily dependent...