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1

Flightweight Carbon Nanotube Magnet Technology  

NASA Technical Reports Server (NTRS)

Virtually all plasma-based systems for advanced airborne/spaceborne propulsion and power depend upon the future availability of flightweight magnet technology. Unfortunately, current technology for resistive and superconducting magnets yields system weights that tend to counteract the performance advantages normally associated with advanced plasma-based concepts. The ongoing nanotechnology revolution and the continuing development of carbon nanotubes (CNT), however, may ultimately relieve this limitation in the near future. Projections based on recent research indicate that CNTs may achieve current densities at least three orders of magnitude larger than known superconductors and mechanical strength two orders of magnitude larger than steel. In fact, some published work suggests that CNTs are superconductors. Such attributes imply a dramatic increase in magnet performance-to-weight ratio and offer real hope for the construction of true flightweight magnets. This Technical Publication reviews the technology status of CNTs with respect to potential magnet applications and discusses potential techniques for using CNT wires and ropes as a winding material and as an integral component of the containment structure. The technology shortfalls are identified and a research and technology strategy is described that addresses the following major issues: (1) Investigation and verification of mechanical and electrical properties, (2) development of tools for manipulation and fabrication on the nanoscale, (3) continuum/molecular dynamics analysis of nanotube behavior when exposed to practical bending and twisting loads, and (4) exploration of innovative magnet fabrication techniques that exploit the natural attributes of CNTs.

Chapman, J. N.; Schmidt, H. J.; Ruoff, R. S.; Chandrasekhar, V.; Dikin, D. A.; Litchford, R. J.

2003-01-01

2

Carbon nanotubes in confined magnetic fields: gap oscillations and  

E-print Network

Carbon nanotubes in confined magnetic fields: gap oscillations and persistent currents from a new;OutlineOutline Aharonov-Bohm oscillations in Carbon nanotubes Curvature effects Persistent currents #12 as a change in the interference pattern #12;The AB effect in carbon nano-tubes (CNTs) (I) A. Bachtold et al

Marini, Andrea

3

Chemical method of filling carbon nanotubes with magnetic material  

NASA Astrophysics Data System (ADS)

A versatile chemical method is used to fill multi-wall carbon nanotubes (MWCNTs) with magnetic material. The process appears to open up tips of 100% of MWCNTs that are observed but the filling yield is rather low. The filling yield improved greatly by introducing metal chelating polymer, chitosan, in the nanotubes. Mössbauer measurements of the filled MWCNTs suggest the presence of magnetic and non-magnetic phases of Fe nanoparticles. The hyperfine magnetic field of the magnetic phase increased from its room temperature value of 182-251 kOe at 20 K.

Seifu, Dereje; Hijji, Yousef; Hirsch, Gary; Karna, Shashi P.

4

Carbon nanotubes and magnetic nanomaterials as substratum for neuroscience applications  

NASA Astrophysics Data System (ADS)

Nanomaterials have, for the last 10-15 years, been seriously researched for applications ranging from conducting polymers, composites, chemical, biological sensors, etc. Carbon nanotubes have been researched for incorporation with biological sensors and delivery systems. Researchers have shown that their compatible size, bio-friendly inert nature, non-fouling, multiple functional chemistries, and excellent conducting properties give rise to a possibility of utilizing them as scaffold material for the growth and proliferation of biological cells, like neurons. Neurons damaged as part of gradual degradation or through impact injuries leave patients with severely debilitating conditions. The use of Carbon Nanotubes as a substratum to support neural growth has been studied, while the development of magnetic nanotubes opens the possibility of developing a non-invasive method using magnetic fields and for therapeutic/restorative devices for alleviating nervous system disorders. A combination of nanomaterials coupled with magnetic fields can be utilized for the development of such devices. The research described in this dissertation details the experiments conducted to compare carbon nanotubes, hematite nanotubes and magnetite nanowires as a substratum for neuronal growth. The effect of low magnetic fields (23.7 Ga) in combination with the various nanomaterials on the growth of neurites was also studied. The growth characteristics were compared against a standard control sample without the influence of nanomaterial substrates and magnetic fields. The levels of cell death caused by each kind of nanomaterial were also examined to ascertain a suitable material for the future development of a therapeutic/restorative neural probe/sensor.

Aatre, Kiran R.

5

Alloy hydride catalyst route for the synthesis of single-walled carbon nanotubes, multi-walled carbon nanotubes and magnetic metal-filled multi-walled carbon nanotubes  

Microsoft Academic Search

This paper presents a novel, cost-effective and single-step technique for the synthesis of single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes (MWNTs) and magnetic metal-filled MWNTs using a fixed bed reaction thermal chemical vapour deposition (CVD) using alloy hydride catalyst. The single-step method involves the pyrolysis of methane at suitable temperatures over fine powders of certain Mischmetal-based AB3 alloy hydride catalysts,

A. Leela Mohana Reddy; M. M. Shaijumon; S. Ramaprabhu

2006-01-01

6

Microwave absorption of magnetized hydrogen plasma in carbon nanotubes  

SciTech Connect

A simple model to describe the microwave absorption of magnetized hydrogen plasma embedded inside the carbon nanotubes (CNTs), which were grown by iron-catalyzed high-pressure disproportionation (HiPco), is proposed and analyzed. By using Maxwell equations in conjunction with a general expression of the complex permittivity of magnetized hydrogen plasma in HiPco CNTs, known as the Appleton-Hartree formula, the absorption coefficients of the system for right-hand circularly wave propagation along and across the static magnetic field are obtained. The effects of the continuously changing the electron density, the collision frequency, and the cyclotron frequency on the absorption of the microwave are discussed.

Moradi, Afshin [Department of Nano Science, Kermanshah University of Technology, Kermanshah (Iran, Islamic Republic of) and Department of Nano Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), Tehran (Iran, Islamic Republic of)

2009-11-15

7

Magnetorheological properties of a magnetic nanofluid with dispersed carbon nanotubes  

NASA Astrophysics Data System (ADS)

We investigate the effect of multiwalled carbon nanotubes (MWCNTs) on the magnetorheological properties of an oil based magnetic nanofluid (ferrofluid). The shear resistant plateau observed in a pure ferrofluid disappears when 0.5 wt % of MWCNT is incorporated. The yield stress values of the composite system are slightly smaller than that of the pure system. This shows that the presence of carbon nanotubes (CNTs) weakens the magnetic field induced microstructure of the ferrofluid due to their interaction that affects the hydrodynamic and magnetic interactions between the dispersed nanoparticles. Interestingly, the Mason number plots for both the pure and composite system show scaling of the viscosity curves onto a single master curve for magnetic fields of 80 mT and above while deviations are observed for lower magnetic fields. The weakening of the ferrofluid microstructure in the presence of CNTs is further evident in the amplitude sweep measurements where the linear viscoelastic region develops only at a higher magnetic field strength compared to lower magnetic fields in pure ferrofluids. These results are useful for tailoring ferrofluids with a faster response for various applications.

Felicia, Leona J.; Philip, John

2014-02-01

8

Magnetorheological properties of a magnetic nanofluid with dispersed carbon nanotubes.  

PubMed

We investigate the effect of multiwalled carbon nanotubes (MWCNTs) on the magnetorheological properties of an oil based magnetic nanofluid (ferrofluid). The shear resistant plateau observed in a pure ferrofluid disappears when 0.5 wt% of MWCNT is incorporated. The yield stress values of the composite system are slightly smaller than that of the pure system. This shows that the presence of carbon nanotubes (CNTs) weakens the magnetic field induced microstructure of the ferrofluid due to their interaction that affects the hydrodynamic and magnetic interactions between the dispersed nanoparticles. Interestingly, the Mason number plots for both the pure and composite system show scaling of the viscosity curves onto a single master curve for magnetic fields of 80 mT and above while deviations are observed for lower magnetic fields. The weakening of the ferrofluid microstructure in the presence of CNTs is further evident in the amplitude sweep measurements where the linear viscoelastic region develops only at a higher magnetic field strength compared to lower magnetic fields in pure ferrofluids. These results are useful for tailoring ferrofluids with a faster response for various applications. PMID:25353475

Felicia, Leona J; Philip, John

2014-02-01

9

Sensitive magnetic force detection with a carbon nanotube resonator  

SciTech Connect

We propose a technique for sensitive magnetic point force detection using a suspended carbon nanotube (CNT) mechanical resonator combined with a magnetic field gradient generated by a ferromagnetic gate electrode. Numerical calculations of the mechanical resonance frequency show that single Bohr magneton changes in the magnetic state of an individual magnetic molecule grafted to the CNT can translate to detectable frequency shifts, on the order of a few kHz. The dependences of the resonator response to device parameters such as length, tension, CNT diameter, and gate voltage are explored and optimal operating conditions are identified. A signal-to-noise analysis shows that, in principle, magnetic switching at the level of a single Bohr magneton can be read out in a single shot on timescales as short as 10??s. This force sensor should enable new studies of spin dynamics in isolated single molecule magnets, free from the crystalline or ensemble settings typically studied.

Willick, Kyle [Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Haapamaki, Chris [Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Baugh, Jonathan, E-mail: baugh@iqc.ca [Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

2014-03-21

10

Magnetic nanoparticle decorated multi-walled carbon nanotubes for removing copper ammonia complex from water.  

PubMed

A kind of novel magnetic carbon nanotube composite was prepared and designed for wastewater treatment. Multi-walled carbon nanotubes were decorated with magnetic iron oxide nanoparticles, with an uniform distribution on the nanotube surface. The functionalized carbon nanotubes exhibit superparamagnetic behavior and can be easily and rapidly separated from the dispersion via a magnetic process. The carbon nanotube-iron oxide composites might serve as adsorbent for contaminant adsorption in water, especially for copper ammonia complex removal. The adsorption of copper ammonia complex to carbon nanotube-iron oxide composites is time dependent, and they can be quickly and efficiently removed together through a magnetic separation process. This novel magnetic composites might serve as an efficient and proper adsorbent in wastewater treatment applications. PMID:23755622

Dai, Mingzhu; Li, Jun; Kang, Bin; Ren, Chao; Chang, Shuquan; Dai, Yaodong

2013-03-01

11

Carbon nanotubes terminated with hard magnetic FePt nanomagnets  

NASA Astrophysics Data System (ADS)

The advancement in carbon nanotube (CNT) technology includes significant interest in their functionalization to modify their chemical and physical properties. In particular, the selective functionalization of the CNT ends opens exciting opportunities to design nanoscale architectures and networks. The realization of hard-magnetically terminated CNT via plasma enhanced chemical vapor deposition from Fe-Pt thin films is reported. Although FePt is rarely used as a catalyst for CNT synthesis the said binary catalyst affords attractive hard magnetic properties when present in the chemically ordered L10 phase.

Schäffel, F.; Täschner, C.; Rümmeli, M. H.; Neu, V.; Wolff, U.; Queitsch, U.; Pohl, D.; Kaltofen, R.; Leonhardt, A.; Rellinghaus, B.; Büchner, B.; Schultz, L.

2009-05-01

12

Magnetic damping of a carbon nanotube nano-electromechanical resonator  

NASA Astrophysics Data System (ADS)

A suspended, doubly clamped single-wall carbon nanotube is characterized at cryogenic temperatures. We observe specific switching effects in dc-current spectroscopy of the embedded quantum dot. These have been identified previously as nano-electromechanical self-excitation of the system, where positive feedback from single-electron tunneling drives mechanical motion. A magnetic field suppresses this effect, by providing an additional damping mechanism. This is modeled by eddy current damping, and confirmed by measuring the resonance quality factor of the radio-frequency-driven nano-electromechanical resonator in an increasing magnetic field.

Schmid, D. R.; Stiller, P. L.; Strunk, Ch; Hüttel, A. K.

2012-08-01

13

Anisotropic conductivity of magnetic carbon nanotubes embedded in epoxy matrices  

PubMed Central

Maghemite (?-Fe2O3)/multi-walled carbon nanotubes (MWCNTs) hybrid-materials were synthesized and their anisotropic electrical conductivities as a result of their alignment in a polymer matrix under an external magnetic field were investigated. The tethering of ?-Fe2O3 nanoparticles on the surface of MWCNT was achieved by a modified sol-gel reaction, where sodium dodecylbenzene sulfonate (NaDDBS) was used in order to inhibit the formation of a 3D iron oxide gel. These hybrid-materials, specifically, magnetized multi-walled carbon nanotubes (m-MWCNTs) were readily aligned parallel to the direction of a magnetic field even when using a relatively weak magnetic field. The conductivity of the epoxy composites formed in this manner increased with increasing m-MWCNT mass fraction in the polymer matrix. Furthermore, the conductivities parallel to the direction of magnetic field were higher than those in the perpendicular direction, indicating that the alignment of the m-MWCNT contributed to the enhancement of the anisotropic electrical properties of the composites in the direction of alignment. PMID:23019381

Kim, Il Tae; Tannenbaum, Allen; Tannenbaum, Rina

2010-01-01

14

Magnetic nanotubes  

DOEpatents

A magnetic nanotube includes bacterial magnetic nanocrystals contacted onto a nanotube which absorbs the nanocrystals. The nanocrystals are contacted on at least one surface of the nanotube. A method of fabricating a magnetic nanotube includes synthesizing the bacterial magnetic nanocrystals, which have an outer layer of proteins. A nanotube provided is capable of absorbing the nanocrystals and contacting the nanotube with the nanocrystals. The nanotube is preferably a peptide bolaamphiphile. A nanotube solution and a nanocrystal solution including a buffer and a concentration of nanocrystals are mixed. The concentration of nanocrystals is optimized, resulting in a nanocrystal to nanotube ratio for which bacterial magnetic nanocrystals are immobilized on at least one surface of the nanotubes. The ratio controls whether the nanocrystals bind only to the interior or to the exterior surfaces of the nanotubes. Uses include cell manipulation and separation, biological assay, enzyme recovery, and biosensors.

Matsui, Hiroshi (Glen Rock, NJ); Matsunaga, Tadashi (Tokyo, JP)

2010-11-16

15

Imaging Carbon Nanotubes in High Performance Polymer Composites via Magnetic Force Microscope  

NASA Technical Reports Server (NTRS)

Application of carbon nanotubes as reinforcement in structural composites is dependent on the efficient dispersion of the nanotubes in a high performance polymer matrix. The characterization of such dispersion is limited by the lack of available tools to visualize the quality of the matrix/carbon nanotube interaction. The work reported herein demonstrates the use of magnetic force microscopy (MFM) as a promising technique for characterizing the dispersion of nanotubes in a high performance polymer matrix.

Lillehei, Peter T.; Park, Cheol; Rouse, Jason H.; Siochi, Emilie J.; Bushnell, Dennis M. (Technical Monitor)

2002-01-01

16

Carbon nanotube decorated magnetic microspheres as an affinity matrix for biomolecules  

E-print Network

Carbon nanotube decorated magnetic microspheres as an affinity matrix for biomolecules Hayriye ¨Unal and Javed H. Niazi* Carbon nanotube (CNT) decorated magnetic microspheres were fabricated separate biomolecules. Hybrid CNT-microspheres prepared by a feasible method reported herein had a well

Yanikoglu, Berrin

17

Anomalous magnetization of a carbon nanotube as an excitonic insulator  

NASA Astrophysics Data System (ADS)

We show theoretically that an undoped carbon nanotube might be an excitonic insulator—the long-sought phase of matter proposed by Keldysh, Kohn, and others fifty years ago. We predict that the condensation of triplet excitons, driven by intervalley exchange interaction, spontaneously occurs at equilibrium if the tube radius is sufficiently small. The signatures of exciton condensation are its sizable contributions to both the energy gap and the magnetic moment per electron. The increase of the gap might have already been measured, albeit with a different explanation [V. V. Deshpande, B. Chandra, R. Caldwell, D. S. Novikov, J. Hone, and M. Bockrath, Science 323, 106 (2009), 10.1126/science.1165799]. The enhancement of the quasiparticle magnetic moment is a pair-breaking effect that counteracts the weak paramagnetism of the ground-state condensate of excitons. This property could rationalize the anomalous magnitude of magnetic moments recently observed in different devices close to charge neutrality.

Rontani, Massimo

2014-11-01

18

Control of Magnetic Properties of Carbon Nanotubes Filled with Iron  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) filled with iron nanowires show high coercivity owing to their shape anisotropy originating from the high-aspect-ratio shapes of the iron nanowires. In this study, CNTs filled with iron were prepared by the thermal chemical vapor deposition (T-CVD) method using ferrocene as a precursor, and the magnetic properties of the synthesized CNTs were examined in detail. It was found that the CVD temperature and the amount of the ferrocene introduced into the CVD reactor influence the amount of CNT growth and the magnetic properties. The high coercivity of approximately 1.6 kOe or higher was obtained under certain CVD conditions. The selected-area electron diffraction analysis showed that the magnetic properties of the CNTs filled with iron are determined by the crystal structure (?-Fe or Fe3C) of the iron nanowires, which can be controlled by the amount of the ferrocene supplied during CVD.

Sato, Hideki; Nagata, Atsushi; Kubonaka, Nobuo; Fujiwara, Yuji

2013-11-01

19

Single-step synthesis and magnetic separation of graphene and carbon nanotubes in arc discharge plasmas  

Microsoft Academic Search

The unique properties of graphene and carbon nanotubes made them the most promising nanomaterials attracting enormous attention, due to the prospects for applications in various nanodevices, from nanoelectronics to sensors and energy conversion devices. Here we report on a novel deterministic, single-step approach to simultaneous production and magnetic separation of graphene flakes and carbon nanotubes in an arc discharge by

O. Volotskova; I. Levchenko; A. Shashurin; Y. Raitses; K. Ostrikov; M. Keidar

2010-01-01

20

Electrostatic waves in carbon nanotubes with an axial magnetic field  

NASA Astrophysics Data System (ADS)

Based on a linearized hydrodynamic model and within the quasi-static approximation, the dispersion relation of electrostatic waves propagating through single-walled carbon nanotubes subject to an axial magnetic field is theoretically explored. In the classical limit, we obtain two main possible waves which in turn are divided into two branches, a low-frequency acoustical and a high-frequency optical plasmon branch. In the quantum case, we have found that the dispersion relation is substantially modified when the electron wavelength becomes large enough compared to the propagation wavelength of the electrostatic waves in the quantum plasma. We also show that the axial magnetic field manifest itself on the perturbed electron density through the quantum term and gives rise to the propagation of the electrostatic waves within the quantum plasma. As a result, the effect of the magnetic field is pronounced in the plasma dispersion relations in such a way that their curves approach to zero when the magnetic field is weak; and for the strong magnetic field, they asymptotically meet the constant lines.

Abdikian, Alireza; Bagheri, Mehran

2013-10-01

21

Magnetic Property Measurements on Single Wall Carbon Nanotube-Polyimide Composites  

NASA Technical Reports Server (NTRS)

Temperature and magnetic field dependent magnetization measurements were performed on polyimide nanocomposite samples, synthesized with various weight percentages of single wall carbon nanotubes. It was found that the magnetization of the composite, normalized to the mass of nanotube material in the sample, decreased with increasing weight percentage of nanotubes. It is possible that the interfacial coupling between the carbon nanotube (CNT) fillers and the polyimide matrix promotes the diamagnetic response from CNTs and reduces the total magnetization of the composite. The coercivity of the samples, believed to originate from the residual magnetic catalyst particles, was enhanced and had a stronger temperature dependence as a result of the composite synthesis. These changes in magnetic properties can form the basis of a new approach to investigate the interfacial properties in the CNT nanocomposites through magnetic property measurements.

Sun, Keun J.; Wincheski, Russell A.; Park, Cheol

2008-01-01

22

Selective actuation of arrays of carbon nanotubes using magnetic resonance.  

PubMed

We introduce the use of ferromagnetic resonance (FMR) to actuate mechanical resonances in as grown arrays of carbon nanotubes (CNTs) loaded with Ni particles (Ni-CNTs). This contactless method is closely related to the magnetic resonance force microscopy technique and provides spatial selectivity of actuation along the array. The Ni-CNT arrays are grown by chemical vapor deposition and are composed of homogeneous CNTs with uniform length (~600 nm) and almost equal diameter (~20 nm), which are loaded with Ni catalyst particles at their tips due to the tip growth mode. The vibrations of the Ni-CNTs are actuated by relying on the driving force that appears due to the FMR excited at about 2 GHz in the Ni particles (diameter ~100 nm). The Ni-CNT oscillations (frequency ~40 MHz) are detected mechanically by atomic force microscopy. The acquired oscillation images of the Ni-CNT uniform array reveal clear maxima in the spatial distribution of the oscillation amplitudes. We attribute these maxima to the "sensitive slices", i.e., the spatial regions of the Ni-CNT array where the FMR condition is met. Similar to magnetic resonance imaging, the sensitive slice is determined by the magnetic field gradient and moves along the Ni-CNT array as the applied magnetic field is ramped. Our excitation method does not require the presence of any additional microfabricated electrodes or coils near the CNTs and is particularly advantageous in cases where the traditional electrical actuation methods are not effective or cannot be implemented. The remote actuation can be effectively implemented also for arrays of other magnetic nanomechanical resonators. PMID:23742039

Volodin, Alexander; Santini, Claudia A; De Gendt, Stefan; Vereecken, Philippe M; Van Haesendonck, Chris

2013-07-23

23

Magnetic configuration dependence of magnetoresistance in a Fe-porphyrin-like carbon nanotube spintronic device  

SciTech Connect

By using nonequilibrium Green's functions in combination with the density functional theory, we investigate the spin-dependent transport properties in a Fe-porphyrin-like carbon nanotube spintronic device. The results show that magnetoresistance ratio is strongly dependent on the magnetic configuration of the Fe-porphyrin-like carbon nanotube. Under the application of the external magnetic field, the magnetoresistance ratio of the device can be increased from about 19% to about 1020% by tuning the magnetic configuration in the device. Our results confirm that the magnetic configuration is a key factor for obtaining a high-performance spintronic device.

Zeng, Jing; Chen, Ke-Qiu, E-mail: keqiuchen@hnu.edu.cn [Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, Department of Applied Physics, Hunan University, Changsha 410082 (China)

2014-01-20

24

Effects of boron-doping on the morphology and magnetic property of carbon nanotubes  

Microsoft Academic Search

Boron carbide nanotubes (nano-fibers) was prepared by B powder and carbon nanotubes (CNTs) at high temperature in a vacuumed\\u000a quartz tube. The morphology, microstructure, component and magnetic property of samples were characterized by transmission\\u000a electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and magnetic property measurement\\u000a system (MPMS) controller. The results showed that B-doping CNTs have great difference

Qi Jiang; Lan Qian; Jing Yi; Xiaotong Zhu; Yong Zhao

2007-01-01

25

Carbon Nanotube Quantum Dot  

E-print Network

Carbon Nanotube Quantum Dot with Superconducting Electrodes Bachelor of Science Thesis Faculty of march 2010. The study of the electrical properties of carbon nanotubes falls under meso- scopic physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3 Theory 8 3.1 Carbon Nanotubes . . . . . . . . . . . . . . . . . . . . . . . . 8 3

Nygård, Jesper

26

Photophysics of carbon nanotubes  

E-print Network

This thesis reviews the recent advances made in optical studies of single-wall carbon nanotubes. Studying the electronic and vibrational properties of carbon nanotubes, we find that carbon nanotubes less than 1 nm in ...

Samsonidze, Georgii G

2007-01-01

27

Endowing carbon nanotubes with superparamagnetic properties: applications for cell labeling, MRI cell tracking and magnetic manipulations.  

PubMed

Coating of carbon nanotubes (CNTs) with magnetic nanoparticles (NPs) imparts novel magnetic, optical, and thermal properties with potential applications in the biomedical domain. Multi-walled CNTs have been decorated with iron oxide superparamagnetic NPs. Two different approaches have been investigated based on ligand exchange or "click chemistry". The presence of the NPs on the nanotube surface allows conferring magnetic properties to CNTs. We have evaluated the potential of the NP/CNT hybrids as a contrast agent for magnetic resonance imaging (MRI) and their interactions with cells. The capacity of the hybrids to magnetically monitor and manipulate cells has also been investigated. The NP/CNTs can be manipulated by a remote magnetic field with enhanced contrast in MRI. They are internalized into tumor cells without showing cytotoxicity. The labeled cells can be magnetically manipulated as they display magnetic mobility and are detected at a single cell level through high resolution MRI. PMID:23579421

Lamanna, Giuseppe; Garofalo, Antonio; Popa, Gabriela; Wilhelm, Claire; Bégin-Colin, Sylvie; Felder-Flesch, Delphine; Bianco, Alberto; Gazeau, Florence; Ménard-Moyon, Cécilia

2013-05-21

28

Magnetic heterogeneity and alignment of single wall carbon nanotubes M. F. Islam, D. E. Milkie, O. N. Torrens, A. G. Yodh, and J. M. Kikkawa  

E-print Network

Magnetic heterogeneity and alignment of single wall carbon nanotubes M. F. Islam, D. E. Milkie, O that a fraction of acid purified single wall carbon nanotubes SWNTs exhibit both linear-orbital diamagnetic and s : 78.30.Na, 78.66.Tr, 78.67.Ch The magnetic responses of single wall carbon nanotubes SWNTs provide

Islam, Mohammad F.

29

Recent advances in the internal functionalization of carbon nanotubes: synthesis, optical, and magnetic resonance studies  

Microsoft Academic Search

The hollow inside of single-wall carbon nanotubes (SWCNT) provides a unique degree of freedom to investigate chemical reactions inside this confined environment and to study the tube properties. It is reviewed herein, how encapsulating fullerenes, magnetic fullerenes, $^{13}$C isotope enriched fullerenes and organic solvents inside SWCNTs enables to yield unprecedented insight into their electronic, optical, and interfacial properties and to

Ferenc Simon; Rudolf Pfeiffer; Hans Kuzmany

2007-01-01

30

In vivo detection of magnetic labeled oxidized multi-walled carbon nanotubes by magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Functionalized carbon nanotubes (f-CNTs) have been widely used in bio-medicine as drug carriers, bio-sensors, imaging agents and tissue engineering additives, which demands better understanding of their in vivo behavior because of the increasing exposure potential to humans. However, there are limited studies to investigate the in vivo biodistribution and elimination of f-CNTs. In this study, superparamagnetic iron oxides (SPIOs) were used to label oxidized multiwalled carbon nanotubes (o-MWCNTs) for in vivo distribution study of o-MWCNTs by magnetic resonance imaging (MRI). SPIO labeled o-MWCNTs ((SPIO)o-MWCNTs) were prepared by a hydrothermal reaction process, and characterized by TEM, XRD and magnetometer. (SPIO)o-MWCNTs exhibited superparamagnetic property, excellent biocompatibility and stability. The intravenously injected (SPIO)o-MWCNTs were observed in liver, kidney and spleen, while the subcutaneously injected (SPIO)o-MWCNTs could be only detected in sub mucosa. Most of the intravenously injected (SPIO)o-MWCNTs could be eliminated from liver, spleen, kidney and sub mucosa on 4 d post injection (P.I.). However, the residual o-MWCNTs could induce 30–40% MRI signal-to-noise ratio changes in these tissues even on 30 d P.I. This in vivo biodistribution and elimination information of o-MWCNTs will greatly facilitate the application of f-CNT based nanoproducts in biomedicine. In addition, the magnetic labeling method provides an approach to investigate the in vivo biodistribution and clearance of other nanomaterials.

Li, Ruibin; Wu, Ren’an; Zhao, Liang; Qin, Hongqiang; Wu, Jianlin; Zhang, Jingwen; Bao, Ruyi; Zou, Hanfa

2014-12-01

31

Synthesis and magnetic properties of multiwalled carbon nanotubes decorated with magnetite nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetite particles with nanoscale sizes were deposited along multiwalled carbon nanotubes (MWCNT) through a simple, effective and reproducible chemical route. The structure, morphology and magnetic properties of the hybrid materials were characterized by XRD, SEM, TEM, EDX, VSM. The characterization results show that the surface of nanotubes was loaded with iron oxides nanoclusters and each nanocluster is composed by several nanocrystals with a mean diameter of 10 nm. The experimental magnetic hysteretic behavior has been also studied by means of the Preisach model and a good agreement between experimental data and numerical computations was found.

Pistone, A.; Iannazzo, D.; Fazio, M.; Celegato, F.; Barrera, G.; Tiberto, P.; Giordano, A.; Azzerboni, B.; Galvagno, S.

2014-02-01

32

Magneto-Coulomb effect in carbon nanotube quantum dots filled with magnetic nanoparticles.  

PubMed

Electrical transport measurements of carbon nanotubes filled with magnetic iron nanoparticles are reported. Low-temperature (40 mK) magnetoresistance measurements showed conductance hysteresis with sharp jumps at the switching fields of the nanoparticles. Depending on the gate voltage, positive or negative hysteresis was observed. The results are explained in terms of a magneto-Coulomb effect: The spin flip of the iron island at a nonzero magnetic field causes a shift of the chemical potential induced by the change of Zeeman energy; i.e., an effective charge variation is detected by the nanotube quantum dot. PMID:22107663

Datta, S; Marty, L; Cleuziou, J P; Tilmaciu, C; Soula, B; Flahaut, E; Wernsdorfer, W

2011-10-28

33

Synthesis, characterization and magnetic properties of carbon nanotubes decorated with magnetic MIIFe2O4 nanoparticles  

NASA Astrophysics Data System (ADS)

In this study, a simple, efficient and reproducible microemulsion method was applied for the successful decoration of carbon nanotubes (CNTs) with magnetic MIIFe2O4 (M = Co, Ni, Cu, Zn) nanoparticles. The structure, composition and morphology of the prepared nanocomposite materials were characterized using X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The magnetic properties were investigated by the vibrating sample magnetometer (VSM). The SEM results illustrated that large quantity of MIIFe2O4 nanoparticles were uniformly decorated around the circumference of CNTs and the sizes of the nanoparticles ranged from 15 to 20 nm. Magnetic hysteresis loop measurements revealed that all the MIIFe2O4/CNTs nanocomposites displayed ferromagnetic behavior at 300 K and can be manipulated using an external magnetic field. The CoFe2O4/CNTs nanocomposite showed maximum value of saturation magnetization which was 37.47 emu g-1. The as prepared MIIFe2O4/CNTs nanocomposites have many potential application in magnetically guided targeted drug delivery, clinical diagnosis, electrochemical biosensing, magnetic data storage and magnetic resonance imaging.

Ali, Syed Danish; Hussain, Syed Tajammul; Gilani, Syeda Rubina

2013-04-01

34

Magnetically induced changes in diameter and deposition rate of single-walled carbon nanotubes in arc discharge  

NASA Astrophysics Data System (ADS)

A high magnetic field of 10 T was applied to the synthesis of single-walled carbon nanotubes (SWCNTs) by arc discharge in order to control the morphological properties, e.g., diameter, and to improve the deposition rate. The deposition rate of carbonaceous deposits increased by one order of magnitude under a magnetic field of 10 T owing to magnetically induced effects. The average diameter of the SWCNTs also increased to about 1.3 nm with the magnetic field, which was about 1.5 times larger than the average diameter of about 0.8 nm without the magnetic field. This indicates that the morphology and deposition rate of the carbon nanotubes can be controlled by applying a high magnetic field during arc processing. The effects of a magnetic field on the control of carbon nanotube fabrication are explained in terms of electromagnetic effects on the dense arc plasma with high energy, not spin-associated effects on nanotube formation.

Yokomichi, Haruo; Ichihara, Masaki; Kishimoto, Naoki

2014-02-01

35

Carbon Nanotube Image Gallery  

NSDL National Science Digital Library

The mission of NanoLab, Inc. is to utilize nanoscale science and engineering to create high value products from carbon nanotubes, aligned carbon nanotube arrays, and other nanomaterials. This website provides an image gallery of: carbon nanotubes, nanoparticles, nanowire, as well as nanotube fillings, coatings, and arrays.

36

Hyperspectral imaging of exciton photoluminescence in individual carbon nanotubes controlled by high magnetic fields.  

PubMed

Semiconducting carbon nanotubes (CNTs) provide an exceptional platform for studying one-dimensional excitons (bound electron-hole pairs), but the role of defects and quenching centers in controlling emission remains controversial. Here we show that, by wrapping the CNT in a polymer sheath and cooling to 4.2 K, ultranarrow photoluminescence (PL) emission line widths below 80 ?eV can be seen from individual solution processed CNTs. Hyperspectral imaging of the tubes identifies local emission sites and shows that some previously dark quenching segments can be brightened by the application of high magnetic fields, and their effect on exciton transport and dynamics can be studied. Using focused high intensity laser irradiation, we introduce a single defect into an individual nanotube which reduces its quantum efficiency by the creation of a shallow bound exciton state with enhanced electron-hole exchange interaction. The emission intensity of the nanotube is then reactivated by the application of the high magnetic field. PMID:25158099

Alexander-Webber, Jack A; Faugeras, Clement; Kossacki, Piotr; Potemski, Marek; Wang, Xu; Kim, Hee Dae; Stranks, Samuel D; Taylor, Robert A; Nicholas, Robin J

2014-09-10

37

Fast Characterization of Magnetic Impurities in Single-Wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

We have demonstrated that the magnetic susceptibility measurement is a non-destructive, fast and accurate method to determine the residual metal catalysts in a few microgram single-wall carbon nanotube (SWCNT) sample. We have studied magnetic impurities in raw and purified SWCNT by magnetic susceptibility measurements, transmission electron microscopy, and thermogravimetry. The data suggest that the saturation magnetic moment and the effective field, which is caused by the interparticle interactions, decreases and increases respectively with the decrease of the particle size. Methods are suggested to overcome the uncertainty associated.

Chen, Feng; Xue, Y. Y.; Hadijiev, Viktor G.; Chu, C. W.; Nikolaev, Pasha; Arepalli, Sivaram

2003-01-01

38

Quantitative magnetic force microscopy on permalloy dots using an iron filled carbon nanotube probe.  

PubMed

An iron filled carbon nanotube (FeCNT), a 10-40 nm ferromagnetic nanowire enclosed in a protective carbon tube, is an attractive candidate for a magnetic force microscopy (MFM) probe as it provides a mechanically and chemically robust, nanoscale probe. We demonstrate the probe's capabilities with images of the magnetic field gradients close to the surface of a Py dot in both the multi-domain and vortex states. We show the FeCNT probe is accurately described by a single magnetic monopole located at its tip. Its effective magnetic charge is determined by the diameter of the iron wire and its saturation magnetization 4?M(s) ? 2.2 × 10(4)G. A magnetic monopole probe is advantageous as it enables quantitative measurements of the magnetic field gradient close to the sample surface. The lateral resolution is defined by the diameter of the iron wire and the probe-sample separation. PMID:21864777

Wolny, F; Obukhov, Y; Mühl, T; Weissker, U; Philippi, S; Leonhardt, A; Banerjee, P; Reed, A; Xiang, G; Adur, R; Lee, I; Hauser, A J; Yang, F Y; Pelekhov, D V; Büchner, B; Hammel, P C

2011-07-01

39

Excitation spectroscopy of two-electron shell structures in carbon nanotube quantum dots in magnetic fields  

Microsoft Academic Search

Single-quantum dots have been fabricated in an individual single-wall carbon nanotube, and the single-electron-transport measurements have been carried out at 40 mK. Coulomb diamonds showed an alternate change of the diamond size, an even-odd effect, indicating the two-electron shell filling. An excitation spectroscopy in which a Coulomb oscillation peak was measured in magnetic fields with a large source-drain bias voltage

S. Moriyama; T. Fuse; Y. Aoyagi; K. Ishibashi

2005-01-01

40

Optimization of magnetic field-assisted synthesis of carbon nanotubes for sensing applications.  

PubMed

One of the most effective ways of synthesizing carbon nanotubes is the arc discharge method. This paper describes a system supported by a magnetic field which can be generated by an external coil. An electric arc between two electrodes is stabilized by the magnetic field following mass flux stabilization from the anode to the cathode. In this work four constructions are compared. Different configurations of cathode and coils are calculated and presented. Exemplary results are discussed. The paper describes attempts of magnetic field optimization for different configurations of electrodes. PMID:25295922

Raniszewski, Grzegorz; Pyc, Marcin; Kolacinski, Zbigniew

2014-01-01

41

Magnetic functionalised carbon nanotubes as drug vehicles for cancer lymph node metastasis treatment.  

PubMed

Strategies using carbon-based nanomaterials as carriers for delivering chemotherapeutic drugs to cancers have been described well. Here a novel magnetic lymphatic-targeting drug-delivery system, based on functionalised carbon nanotubes (fCNTs), is presented with the aim of improving the outcome of cancer with lymph node involvement. The potential therapeutic effect of gemcitabine (GEM) loading magnetic multiwalled carbon nanotubes (mMWNTs) was compared with that of GEM loading magnetic-activated carbon particles (mACs) in vitro and in vivo. mMWNTs-GEM and mACs-GEM both had high anti-tumour activity in vitro similar to free drug. Subcutaneous administration of GEM loading magnetic nanoparticles resulted in successful regression and inhibition of lymph node metastasis under the magnetic field, with mMWNTs-GEM superior to mACs-GEM, and more effectively in the high-dose versus low-dose groups. The successful application of intra-lymphatic delivery of chemotherapeutics using mMWNTs highlights the clinical potential of fCNTs for future cancer metastasis treatment with high efficacy and minimum side-effects. PMID:21493061

Yang, Feng; Jin, Chen; Yang, Dong; Jiang, Yongjian; Li, Ji; Di, Yang; Hu, Jianhua; Wang, Changchun; Ni, Quanxing; Fu, Deliang

2011-08-01

42

Space-charge waves in magnetized and collisional quantum plasma columns confined in carbon nanotubes  

NASA Astrophysics Data System (ADS)

We study the dispersion relation of electrostatic waves propagating in a column of quantum magnetized collisional plasma embraced completely by a metallic single-walled carbon nanotubes. The analysis is based on the quantum linearized hydrodynamic formalism of collective excitations within the quasi-static approximation. It is shown when the electronic de Broglie's wavelength of the plasma is comparable in the order of magnitude to the radius of the nanotube, the quantum effects are quite meaningful and our model anticipates one acoustical and two optical space-charge waves which are positioned into three propagating bands. With increasing the nanotube radius, the features of the acoustical branch remain unchanged, yet two distinct optical branches are degenerated and the classical behavior is recovered. This study might provide a platform to create new finite transverse cross section quantum magnetized plasmas and to devise nanometer dusty plasmas based on the metallic carbon nanotubes in the absence of either a drift or a thermal electronic velocity and their existence could be experimentally examined.

Bagheri, Mehran; Abdikian, Alireza

2014-04-01

43

Space-charge waves in magnetized and collisional quantum plasma columns confined in carbon nanotubes  

SciTech Connect

We study the dispersion relation of electrostatic waves propagating in a column of quantum magnetized collisional plasma embraced completely by a metallic single-walled carbon nanotubes. The analysis is based on the quantum linearized hydrodynamic formalism of collective excitations within the quasi-static approximation. It is shown when the electronic de Broglie's wavelength of the plasma is comparable in the order of magnitude to the radius of the nanotube, the quantum effects are quite meaningful and our model anticipates one acoustical and two optical space-charge waves which are positioned into three propagating bands. With increasing the nanotube radius, the features of the acoustical branch remain unchanged, yet two distinct optical branches are degenerated and the classical behavior is recovered. This study might provide a platform to create new finite transverse cross section quantum magnetized plasmas and to devise nanometer dusty plasmas based on the metallic carbon nanotubes in the absence of either a drift or a thermal electronic velocity and their existence could be experimentally examined.

Bagheri, Mehran, E-mail: mh-bagheri@sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, G. C., Evin, Tehran 19835-63113 (Iran, Islamic Republic of)] [Laser and Plasma Research Institute, Shahid Beheshti University, G. C., Evin, Tehran 19835-63113 (Iran, Islamic Republic of); Abdikian, Alireza, E-mail: abdykian@gmail.com [Department of Physics, Malayer University, Malayer 65719-95863 (Iran, Islamic Republic of)] [Department of Physics, Malayer University, Malayer 65719-95863 (Iran, Islamic Republic of)

2014-04-15

44

The advantages of the magnetic structure in ferromagnetic-film-coated carbon nanotube probes  

NASA Astrophysics Data System (ADS)

The magnetic structures of ferromagnetic-film-coated carbon nanotube (CNT) probes and conventional pyramidal probes for a magnetic force microscope (MFM) were simulated using three-dimensional micromagnetic simulation. The CNT-MFM probes with a total probe diameter less than 60 nm are almost uniformly magnetized along the longitudinal direction of the CNT, which is the ideal magnetic structure for MFM observations. On the other hand, the pyramidal probes had a vortex structure around the point tip, which suggests that they require a greater thickness of the ferromagnetic film because only part of the magnetic moment participates in the detection of the z-component of the stray field from samples. The advantages of the CNT-MFM probe are uniform magnetization along the longitudinal direction and magnetic imaging ability using a smaller coating thickness.

Manago, T.; Asada, H.; Uzumaki, T.; Takano, F.; Akinaga, H.; Kuramochi, H.

2012-01-01

45

Electronic and magnetic structure of carbon nanotubes using x-ray absorption and magnetic circular dichroism spectroscopy  

E-print Network

Carbon nanotubes are a fraction of the size of transistors used in today's best microchips, as it could reduce power demands and heating in next electronics revolution. Present study investigates the electronic and magnetic structure of multi walled carbon nanotubes (MWCNT) synthesized by chemical vapor deposition technique using near edge x-ray absorption spectroscopy (NEXAFS) measurement at C K-edge and x-ray magnetic circular dichroism (XMCD) at Co and Fe $L_{3,2}$ -edges. NEXAFS at C K-edge shows significant $\\pi$-bonding, and Fe(Co) L-edge proves the presence of Co$^{2+}$ and Fe$^{2+}$ in octahedral symmetry, and embedded in C-matrix of MWCNT. Element specific hystersis loops and XMCD spectra clearly shows that these MWCNTs exhibits room temperature ferromagnetism. These measurements elucidated the electronic structure of CNTs and presence of magnetic interactions at room temperature.

Gautama, Sanjeev; Augustine, S; Kang, J K; Kim, J -Y; Brookes, N B; Asokan, K; Chae, Keun Hwa

2011-01-01

46

Synthesis of carbon nanotubes.  

PubMed

Carbon nanotubes play a fundamental role in the rapidly developing field of nanoscience and nanotechnology because of their unique properties and high potential for applications. In this article, the different synthesis methods of carbon nanotubes (both multi-walled and single-walled) are reviewed. From the industrial point of view, the chemical vapor deposition method has shown advantages over laser vaporization and electric arc discharge methods. This article also presents recent work in the controlled synthesis of carbon nanotubes with ordered architectures. Special carbon nanotube configurations, such as nanocoils, nanohorns, bamboo-shaped and carbon cylinder made up from carbon nanotubes are also discussed. PMID:16245519

Awasthi, Kalpana; Srivastava, Anchal; Srivastava, O N

2005-10-01

47

Plumbing carbon nanotubes  

NASA Astrophysics Data System (ADS)

Since their discovery, the possibility of connecting carbon nanotubes together like water pipes has been an intriguing prospect for these hollow nanostructures. The serial joining of carbon nanotubes in a controlled manner offers a promising approach for the bottom-up engineering of nanotube structures-from simply increasing their aspect ratio to making integrated carbon nanotube devices. To date, however, there have been few reports of the joining of two different carbon nanotubes. Here we demonstrate that a Joule heating process, and associated electro-migration effects, can be used to connect two carbon nanotubes that have the same (or similar) diameters. More generally, with the assistance of a tungsten metal particle, this technique can be used to seamlessly join any two carbon nanotubes-regardless of their diameters-to form new nanotube structures.

Jin, Chuanhong; Suenaga, Kazu; Iijima, Sumio

2008-01-01

48

Unusual magnetic behavior of SiCN/multiwalled carbon nanotubes nanocomposites  

NASA Astrophysics Data System (ADS)

Multiwalled carbon nanotubes (MWCNTs) have been dispersed homogeneously throughout a preceramic polysilazane matrix. The homogenized mixture was then warm pressed and subsequently pyrolyzed in Ar atmosphere at 1100 °C, yielding an amorphous silicon carbonitride (SiCN)/MWCNT nanocomposite. The hysteresis loop of the 5 vol % CNT/SiCN composite revealed a ferromagneticlike behavior up to 5000 Oe and a semiconductinglike feature at a higher applied field. The magnetic behavior of CNT-rich composites is due mainly to defects and to the interaction between the nanotubes and the SiCN matrix, which is indicated by a shift in the G and D bands of graphitic carbon as determined by Raman spectroscopy.

Francis, A.; Riedel, R.

2009-04-01

49

Aharonov-Bohm Exciton Splittings in Carbon Nanotubes in Ultra-High Magnetic Fields  

NASA Astrophysics Data System (ADS)

The Ajiki-Ando (A-A) splitting of single-walled carbon nanotubes was observed by the magneto-absorption measurements conducted up to a very high magnetic field, 78 T for PFO-samples. The well-resolved absorption spectra from the E11 transitions in the PFO-samples showed a clear A-A splitting. The electro-magnetic flux compression method was used for generation of the field up to 360 T, where the absorption spectra of the E22 transition of the HiPco samples were measured by the streak spectroscopy. Parameters for the A-A splitting were determined for different chiralty of each case.

Takeyama, S.; Suzuki, H.; Otsubo, Y.; Yokoi, H.; Murakami, Y.; Maruyama, S.

2011-12-01

50

Lipid-Modulated Assembly of Magnetized Iron-Filled Carbon Nanotubes in Millimeter-Scale Structures  

NASA Astrophysics Data System (ADS)

Biomolecule-functionalized carbon nanotubes (CNTs) combine the molecular recognition properties of biomaterials with the electrical properties of nanoscale solid state transducers. Application of this hybrid material in bioelectronic devices requires the development of methods for the reproducible self-assembly of CNTs into higher-order structures in an aqueous environment. To this end, we have studied pattern formation of lipid-coated Fe-filled CNTs, with lengths in the 1-5 ?m range, by controlled evaporation of aqueous CNT-lipid suspensions. Novel diffusion limited aggregation structures composed of end-to-end oriented nanotubes were observed by optical and atomic force microscopy. Significantly, the lateral dimension of assemblies of magnetized Fe-filled CNTs was in the millimeter range. Control experiments in the absence of lipids and without magnetization indicated that the formation of these long linear nanotube patterns is driven by a subtle interplay between radial flow forces in the evaporating droplet, lipid-modulated van der Waals forces, and magnetic dipole-dipole interactions.

Toledo, Nashville C.; de Planque, Maurits R. R.; Antoranz Contera, Sonia; Grobert, Nicole; Ryan, John F.

2007-04-01

51

Carbon nanotubes/magnetite hybrids prepared by a facile synthesis process and their magnetic properties  

NASA Astrophysics Data System (ADS)

In this paper, a facile synthesis process is proposed to prepare multiwalled carbon nanotubes/magnetite (MWCNTs/Fe 3O 4) hybrids. The process involves two steps: (1) water-soluble CNTs are synthesized by one-pot modification using potassium persulfate (KPS) as oxidant. (2) Fe 3O 4 is assembled along the treated CNTs by employing a facile hydrothermal process with the presence of hydrazine hydrate as the mineralizer. The treated CNTs can be easily dispersed in aqueous solvent. Moreover, X-ray photoelectron spectroscopy (XPS) analysis reveals that several functional groups such as potassium carboxylate (-COOK), carbonyl (-C dbnd O) and hydroxyl (-C-OH) groups are formed on the nanotube surfaces. The MWCNTs/Fe 3O 4 hybrids are characterized with respect to crystal structure, morphology, element composition and magnetic property by X-ray diffraction (XRD), transmission electron microscopy (TEM), XPS and superconducting quantum interference device (SQUID) magnetometer. XRD and TEM results show that the Fe 3O 4 nanoparticles with diameter in the range of 20-60 nm were firmly assembled on the nanotube surface. The magnetic property investigation indicated that the CNTs/Fe 3O 4 hybrids exhibit a ferromagnetic behavior and possess a saturation magnetization of 32.2 emu/g. Further investigation indicates that the size of assembled Fe 3O 4 nanoparticles can be turned by varying experiment factors. Moreover, a probable growth mechanism for the preparation of CNTs/Fe 3O 4 hybrids was discussed.

Zhang, Li; Ni, Qing-Qing; Natsuki, Toshiaki; Fu, Yaqin

2009-07-01

52

Magnetic carbon nanotubes with particle-free surfaces and high drug loading capacity.  

PubMed

Open-ended, multi-wall carbon nanotubes (CNTs) with magnetic nanoparticles encapsulated within their graphitic walls (magCNTs) were fabricated by a combined action of templated growth and a ferrofluid catalyst/carbon precursor, and tested as drug hosts. The hybrid nanotubes are stable under extreme pH conditions due to particle protection provided by the graphitic shell. The magCNTs are promising for high capacity drug loading given that the magnetic functionalization did not block any of the active sites available for drug attachment, either from the CNT internal void or on the internal and external surfaces. This is in contrast to typical approaches of loading CNTs with particles that proceed through surface attachment or capillary filling of the tube interior. Additionally, the CNTs exhibit enhanced hydrophilic character, as shown by water adsorption measurements, which make them suitable for biological applications. The morphological and structural characteristics of the hybrid CNTs are evaluated in conjunction to their magnetic properties and ability for drug loading (diaminophenothiazine). The fact that the magnetic functionality is provided from 'inside the walls' can allow for multimode functionalization of the graphitic surfaces and makes the magCNTs promising for targeted therapeutic applications. PMID:21817779

Vermisoglou, Eleni C; Pilatos, George; Romanos, George E; Devlin, Eamon; Kanellopoulos, Nick K; Karanikolos, Georgios N

2011-09-01

53

Functionalization and magnetization of carbon nanotubes using Co-60 gamma-ray irradiation  

NASA Astrophysics Data System (ADS)

Functionalized magnetic carbon nanotubes (CNTs) can be used in the biological and biomedical fields as biosensors, drug delivery systems, etc., which makes research into processes for manufacturing modified CNTs quite important. In this paper, Co-60 gamma irradiation is shown to be an effective tool for fabricating functionalized and magnetized CNTs. After the Co-60 gamma irradiation, the presence of carboxylic functional groups on the CNT walls was confirmed by their Fourier transform infrared spectra, and the presence of Fe3O4 was verified by the X-ray diffraction patterns. The functionalized and magnetized CNTs produced using Co-60 gamma irradiation have excellent dispersion properties. The techniques for functionalizing and magnetizing CNTs are introduced in this paper, and applications of the modified CNTs will be reported after more data are gathered.

Chen, C. Y.; Fu, M. J.; Tsai, C. Y.; Lin, F. H.; Chen, K. Y.

2014-10-01

54

The role of multi-walled carbon nanotubes on the magnetic and reflection loss characteristics of substituted strontium ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Substituted strontium ferrite SrFe12-x(Ni0.5Mn0.5Zr)x/2O19/multi-walled carbon nanotubes (MWCNTs) composites were prepared by a sol-gel method. X-ray diffraction patterns confirm the formation of single phase ferrite nanoparticle and nanocomposites of ferrite/carbon nanotubes. Fourier transform infrared spectroscopy demonstrates the existence of functional groups on the surface of carbon nanotubes. Superconducting quantum interference device measurements showed that the values of specific saturation magnetization increases, while coercivity decreases with an increase in substitution content. Zero field cooled magnetization and field cooled magnetization curves display that with an increase in substitution content, the blocking temperature increases. Field emission scanning electron microscopy micrographs demonstrate that ferrite nanoparticles were attached on external surfaces of the carbon nanotubes. The investigation of the microwave absorption indicates that with an addition of carbon nanotubes, the real and imaginary parts of permittivity and reflection loss enhanced. It is found that with increasing the thickness of absorbers, the resonance frequencies shift to lower regime.

Ghasemi, Ali

2013-03-01

55

Composites of Carbon Nanotubes.  

E-print Network

??The purpose of this research was to study various methods of incorporation of single-walled carbon nanotubes (SWNT) with polymers for producing electrically conductive polystyrene composites.… (more)

Tchoul, Maxim N.

2008-01-01

56

Magnetic field induced tailoring of mechanical behavior of fluid filled micro porous carbon nanotube foam  

NASA Astrophysics Data System (ADS)

Compressive loading of the carbon nanotube (CNT) has attracted much attention due to its entangled cellular like structure (CNT foam). This report investigates the mechanical behavior of magnetorheological fluid impregnated micro porous CNT foam that has not been realized before at this scale. Compressive behavior of CNT foam is found to greatly depend on the variation in both fluid viscosity as well as magnetic field intensity. Moreover, maximum achieved stress and energy absorption in CNT foam followed a power law behavior with the magnetic field intensity. Magnetic field induced movement of both CNT and iron oxide particles along the field direction is shown to dominate compressive behavior of CNT foam over highly attractive van der Waals forces between individual CNT. Therefore, this study demonstrates a method for tailoring the mechanical behavior of the fluid impregnated CNT foam.

Reddy, Siva Kumar; Mukherjee, Anwesha; Misra, Abha

2014-06-01

57

Water confined in carbon nanotubes: Magnetic response and proton chemical shieldings  

SciTech Connect

We study the proton nuclear magnetic resonance ({sup 1}H-NMR) of a model system consisting of liquid water in infinite carbon nanotubes (CNT). Chemical shieldings are evaluated from linear response theory, where the electronic structure is derived from density functional theory (DFT) with plane-wave basis sets and periodic boundary conditions. The shieldings are sampled from trajectories generated via first-principles molecular dynamics simulations at ambient conditions, for water confined in (14,0) and (19,0) CNTs with diameters d = 11 {angstrom} and 14.9 {angstrom}, respectively. We find that confinement within the CNT leads to a large ({approx} -23 ppm) upfield shift relative to bulk liquid water. This shift is a consequence of strongly anisotropic magnetic fields induced in the CNT by an applied magnetic field.

Huang, P; Schwegler, E; Galli, G

2008-11-14

58

Magnetic amphiphilic hybrid carbon nanotubes containing N-doped and undoped sections: powerful tensioactive nanostructures  

NASA Astrophysics Data System (ADS)

In this work, unique amphiphilic magnetic hybrid carbon nanotubes (CNTs) are synthesized and used as tensioactive nanostructures in different applications. These CNTs interact very well with aqueous media due to the hydrophilic N-doped section, whereas the undoped hydrophobic one has strong affinity for organic molecules. The amphiphilic character combined with the magnetic properties of these CNTs opens the door to completely new and exciting applications in adsorption science and catalysis. These amphiphilic N-doped CNTs can also be used as powerful tensioactive emulsification structures. They can emulsify water/organic mixtures and by a simple magnetic separation the emulsion can be easily broken. We demonstrate the application of these CNTs in the efficient adsorption of various molecules, in addition to promoting biphasic processes in three different reactions, i.e. transesterification of soybean oil, quinoline extractive oxidation with H2O2 and a metal-catalyzed aqueous oxidation of heptanol with molecular oxygen.In this work, unique amphiphilic magnetic hybrid carbon nanotubes (CNTs) are synthesized and used as tensioactive nanostructures in different applications. These CNTs interact very well with aqueous media due to the hydrophilic N-doped section, whereas the undoped hydrophobic one has strong affinity for organic molecules. The amphiphilic character combined with the magnetic properties of these CNTs opens the door to completely new and exciting applications in adsorption science and catalysis. These amphiphilic N-doped CNTs can also be used as powerful tensioactive emulsification structures. They can emulsify water/organic mixtures and by a simple magnetic separation the emulsion can be easily broken. We demonstrate the application of these CNTs in the efficient adsorption of various molecules, in addition to promoting biphasic processes in three different reactions, i.e. transesterification of soybean oil, quinoline extractive oxidation with H2O2 and a metal-catalyzed aqueous oxidation of heptanol with molecular oxygen. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04005h

Purceno, Aluir D.; Machado, Bruno F.; Teixeira, Ana Paula C.; Medeiros, Tayline V.; Benyounes, Anas; Beausoleil, Julien; Menezes, Helvecio C.; Cardeal, Zenilda L.; Lago, Rochel M.; Serp, Philippe

2014-11-01

59

Nuclear Magnetic Resonance Spectroscopy and Imaging of Carbon Nanotubes  

Microsoft Academic Search

\\u000a Nuclear magnetic resonance (NMR) spectroscopy is one of the most versatile and powerful analytical tools developed in the\\u000a last century and have been proven to be a suitable means for the elucidation of structural properties as well as physico-chemical\\u000a characteristics in chemistry and material sciences. In the first part of this chapter a review is given on the investigation\\u000a of

Vijay K. Anuganti; Aldrik H. Velders

60

Introduction to Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes are among the amazing objects that science sometimes creates by accident, without meaning to, but that will likely revolutionize the technological landscape of the century ahead. Our society stands to be significantly influenced by carbon nanotubes, shaped by nanotube applications in every aspect, just as silicon-based technology still shapes society today. The world already dreams of space-elevators tethered by the strongest of cables, hydrogen-powered vehicles, artificial muscles, and so on - feasts that would be made possible by the emerging carbon nanotube science.

Monthioux, Marc; Serp, Philippe; Flahaut, Emmanuel; Razafinimanana, Manitra; Laurent, Christophe; Peigney, Alain; Bacsa, Wolfgang; Broto, Jean-Marc

61

Design of covalently functionalized carbon nanotubes filled with metal oxide nanoparticles for imaging, therapy, and magnetic manipulation.  

PubMed

Nanocomposites combining multiple functionalities in one single nano-object hold great promise for biomedical applications. In this work, carbon nanotubes (CNTs) were filled with ferrite nanoparticles (NPs) to develop the magnetic manipulation of the nanotubes and their theranostic applications. The challenges were both the filling of CNTs with a high amount of magnetic NPs and their functionalization to form biocompatible water suspensions. We propose here a filling process using CNTs as nanoreactors for high-yield in situ growth of ferrite NPs into the inner carbon cavity. At first, NPs were formed inside the nanotubes by thermal decomposition of an iron stearate precursor. A second filling step was then performed with iron or cobalt stearate precursors to enhance the encapsulation yield and block the formed NPs inside the tubes. Water suspensions were then obtained by addition of amino groups via the covalent functionalization of the external surface of the nanotubes. Microstructural and magnetic characterizations confirmed the confinement of NPs into the anisotropic structure of CNTs making them suitable for magnetic manipulations and MRI detection. Interactions of highly water-dispersible CNTs with tumor cells could be modulated by magnetic fields without toxicity, allowing control of their orientation within the cell and inducing submicron magnetic stirring. The magnetic properties were also used to quantify CNTs cellular uptake by measuring the cell magnetophoretic mobility. Finally, the photothermal ablation of tumor cells could be enhanced by magnetic stimulus, harnessing the hybrid properties of NP loaded-CNTs. PMID:25343751

Liu, Xiaojie; Marangon, Iris; Melinte, Georgian; Wilhelm, Claire; Ménard-Moyon, Cécilia; Pichon, Benoit P; Ersen, Ovidiu; Aubertin, Kelly; Baaziz, Walid; Pham-Huu, Cuong; Bégin-Colin, Sylvie; Bianco, Alberto; Gazeau, Florence; Bégin, Dominique

2014-11-25

62

Nanotube composite carbon fibers  

Microsoft Academic Search

Single walled carbon nanotubes (SWNTs) were dispersed in isotropic petroleum pitch matrices to form nanotube composite carbon fibers with enhanced mechanical and electrical properties. We find that the tensile strength, modulus, and electrical conductivity of a pitch composite fiber with 5 wt % loading of purified SWNTs are enhanced by ~90%, ~150%, and 340% respectively, as compared to the corresponding

R. Andrews; D. Jacques; A. M. Rao; T. Rantell; F. Derbyshire; Y. Chen; J. Chen; R. C. Haddon

1999-01-01

63

Magnetic and highly recyclable macroporous carbon nanotubes for spilled oil sorption and separation.  

PubMed

Development of sorbent materials with high selectivity and sorption capacity, easy collection and recyclability is demanding for spilled oil recovery. Although many sorption materials have been proposed, a systematic study on how they can be reused and possible performance degradation during regeneration remains absent. Here we report magnetic carbon nanotube sponges (Me-CNT sponge), which are porous structures consisting of interconnected CNTs with rich Fe encapsulation. The Me-CNT sponges show high mass sorption capacity for diesel oil reached 56 g/g, corresponding to a volume sorption capacity of 99%. The sponges are mechanically strong and oil can be squeezed out by compression. They can be recycled using through reclamation by magnetic force and desorption by simple heat treatment. The Me-CNT sponges maintain original structure, high capacity, and selectivity after 1000 sorption and reclamation cycles. Our results suggest that practical application of CNT macrostructures in the field of spilled oil recovery is feasible. PMID:23721652

Gui, Xuchun; Zeng, Zhiping; Lin, Zhiqiang; Gan, Qiming; Xiang, Rong; Zhu, Yuan; Cao, Anyuan; Tang, Zikang

2013-06-26

64

Magnetic properties of Co/Pt nanoring arrays deposited on carbon nanotubes  

NASA Astrophysics Data System (ADS)

Multiple Co/Pt bilayers were deposited on vertically aligned carbon nanotubes on an anodic aluminum oxide template. The structural and the magnetic properties of the nanoring arrays were investigated by varying the number of Co/Pt bilayers in the ranges 3-10 in multilayers with a Ta(3.0 nm)/[Co(1.0 nm)/Pt(1.5 nm)]n/Ta(1.0 nm) structure. The thickness and diameter of the nanorings increased with increasing repeat number. Compared with Co/Pt films, the Co/Pt nanoring arrays showed a larger coercivity. However, the magnetostatic interactions between the nanorings became dominant in the reversal behavior and caused a nonsquare hysteresis loop. Giant magnetoresistance structures consisting of multiple Co/Pt bilayers and a thick Cu spacer exhibited magnetization curve that were in good agreement the summation of the moments of layers with varied bilayer repetition.

Yoon, Seungha; Ho Lee, Sang; Kwak, Wonyoung; Nam, Chunghee; Bae Kim, Won; Cho, B. K.

2014-05-01

65

Simultaneous Synthesis of Single-walled Carbon Nanotubes and Graphene in a Magnetically-enhanced Arc Plasma  

PubMed Central

Carbon nanostructures such as single-walled carbon nanotubes (SWCNT) and graphene attract a deluge of interest of scholars nowadays due to their very promising application for molecular sensors, field effect transistor and super thin and flexible electronic devices1-4. Anodic arc discharge supported by the erosion of the anode material is one of the most practical and efficient methods, which can provide specific non-equilibrium processes and a high influx of carbon material to the developing structures at relatively higher temperature, and consequently the as-synthesized products have few structural defects and better crystallinity. To further improve the controllability and flexibility of the synthesis of carbon nanostructures in arc discharge, magnetic fields can be applied during the synthesis process according to the strong magnetic responses of arc plasmas. It was demonstrated that the magnetically-enhanced arc discharge can increase the average length of SWCNT 5, narrow the diameter distribution of metallic catalyst particles and carbon nanotubes 6, and change the ratio of metallic and semiconducting carbon nanotubes 7, as well as lead to graphene synthesis 8. Furthermore, it is worthwhile to remark that when we introduce a non-uniform magnetic field with the component normal to the current in arc, the Lorentz force along the J×B direction can generate the plasmas jet and make effective delivery of carbon ion particles and heat flux to samples. As a result, large-scale graphene flakes and high-purity single-walled carbon nanotubes were simultaneously generated by such new magnetically-enhanced anodic arc method. Arc imaging, scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscopy were employed to analyze the characterization of carbon nanostructures. These findings indicate a wide spectrum of opportunities to manipulate with the properties of nanostructures produced in plasmas by means of controlling the arc conditions. PMID:22330847

Li, Jian; Shashurin, Alexey; Kundrapu, Madhusudhan; Keidar, Michael

2012-01-01

66

Intrinsic and Extrinsic Magnetic Anisotropies of Single-Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Interpretation of bulk magnetization measurements of single-wall carbon nanotubes (SWNTs) is often complicated by the presence of ferromagnetic (FM) catalyst impurities. I will discuss how magnetic alignment of SWNTs in suspension can be used to detect FM impurities attached to nanotubes. A combination of Raman scattering and polarized absorbance is first used to determine the bare optical polarized absorbance cross-sections for light parallel and perpendicular to the nanotube axis. Next, these spectra serve as a benchmark for performing quantitative and high-resolution studies of SWNT alignment in suspensions. These studies reveal that even after chemical purification FM moments significantly enhance SWNT alignment and have an easy axis along the SWNT axis. Lowering the FM impurity content using magnetic gradient fractionation produces a concomitant reduction in the number of SWNTs whose alignment is dominated by FM anisotropy. These studies permit an estimate of the tethered FM moment size for both laser-oven and HiPCO SWNTs, and give an accurate measure of SWNT diamagnetic anisotropy. Studies of DNA-wrapped SWNTs available from DuPont show essentially no FM impurity moment. Since the latter samples can be selectively enriched with single SWNT species, we are able to compare diamagnetic responses for different wrapping vectors (m,n). Work done in collaboration with M.F. Islam, D. E. Milkie, O.N. Torrens, C. L. Kane and A. G. Yodh at PENN and M. Zheng, G.B. Onoa, T. Gierke at DuPont CR&D. Support NSF through DMR-0203378, DMR-079909 and DGE-0221664, NASA through NAG8-2172, DARPA/ONR through N00014-01-1-0831, and SENS.

Kikkawa, J. M.

2005-03-01

67

Magnetic field and electromagnetic wave properties of carbon monoxide with high-pressure disproportionation single-walled carbon nanotubes  

SciTech Connect

A double-fluid theory is used to find the electromagnetic wave absorption of carbon monoxide with iron-catalyzed high-pressure disproportionation (HiPco)-grown single-walled carbon nanotubes (SWNTs). The electromagnetic wave absorption of carbon monoxide with HiPco SWNTs is obtained and is studied numerically. The absorption is then deduced and their functional dependence on the number density, collision frequency, cyclotron frequency, and angle of propagation is studied. The double-fluid theory predicts that there is an electromagnetic frequency dependency on the energy absorption properties of the system under investigation. The calculation results show that effects of magnetic field strength and the angle of microwave propagation on the absorption coefficient as well as the frequency band of resonant absorption are very significant.

Tooski, S. B. [Department of Physics, Laboratory of Materials and Nanotechnology and Laboratory of Applied Physics, Amirkabir University of Technology (Tehran Polytechnic), Tehran P.O. Box 15875-4413 (Iran, Islamic Republic of)

2009-10-15

68

Kinetics and thermodynamics of adsorption of methylene blue by a magnetic graphene-carbon nanotube composite  

NASA Astrophysics Data System (ADS)

A solvothermal method was employed to prepare a novel magnetic composite adsorbent composed of graphene, multi-walled carbon nanotubes (MWCNTs) and Fe3O4 nanoparticles. The prepared adsorbents were characterized by X-ray diffraction, scanning electron microscopy and X-ray fluorescence spectrometry and Fourier transform infrared spectroscopy. Fourier transform infrared spectroscopy and the particle size distribution of the samples before and after adsorption was also carried out. The performance of as-prepared composites was investigated by the adsorption of dye methylene blue. Results showed that the maximum adsorption capacity of the samples was up to 65.79 mg g-1, which was almost equal to the sum of magnetic graphene and magnetic MWCNTs. The effect of pH and temperature on the adsorption performance of methylene blue onto the magnetic adsorbents was investigated. The kinetic was well-described by pseudo-second-order and intraparticle diffusion model, while the isotherm obeyed the Langmuir isotherm. Furthermore, the as-prepared composites were found to be regenerative and reusable. The application in the treatment of an artificial dye wastewater and its cost estimation were also discussed. Therefore, the as-prepared magnetic composites can be severed as a potential adsorbent for removal of dye pollutant, owing to its high adsorption performance, magnetic separability and efficient recyclable property.

Wang, Peifang; Cao, Muhan; Wang, Chao; Ao, Yanhui; Hou, Jun; Qian, Jin

2014-01-01

69

A comparison between magnetic and reflection loss characteristics of substituted strontium ferrite and nanocomposites of ferrite/carbon nanotubes  

NASA Astrophysics Data System (ADS)

Large-scale carbon nanotubes (CNTs)/substituted strontium ferrite nanocomposites have been fabricated by hetero-coagulation. The structure and morphology of nanoparticles and nanocomposites were evaluated by high-resolution transmission electron microscopy (HRTEM). HRTEM confirmed that strontium ferrite was successfully attached to carbon nanotubes. The vibrating sample magnetometer (VSM) confirmed the relatively strong dependence of saturation magnetization with the volume percentage of multi-walled carbon nanotubes (MWCNTs). Reflection loss of nanocomposites at 12-18 GHz was evidently enhanced, as compared to that of strontium ferrite nanoparticles. The maximum reflection loss increased significantly with an increase in volume percentage of MWCNTs. It was proved that the microwave absorbing bandwidth was modulated simply by manipulating the thickness of nanocomposites. Reflection loss evaluations indicate that the nanocomposites display a great potential application as wide-band electromagnetic wave absorbers.

Ghasemi, Ali; Shirsath, Sagar E.; Liu, Xiaoxi; Morisako, Akimitsu

2012-04-01

70

Origami-inspired nanofabrication utilizing physical and magnetic properties of in situ grown carbon nanotubes  

E-print Network

Carbon nanotubes (CNTs), in particular the vertically-aligned variety grown through a plasma enhanced chemical vapor deposition (PECVD)-based process, are highly versatile nanostructures that can be used in a variety of ...

In, Hyun Jin

2010-01-01

71

Iron oxide filled magnetic carbon nanotube-enzyme conjugates for recycling of amyloglucosidase: toward useful applications in biofuel production process.  

PubMed

Biofuels are fast advancing as a new research area to provide alternative sources of sustainable and clean energy. Recent advances in nanotechnology have sought to improve the efficiency of biofuel production, enhancing energy security. In this study, we have incorporated iron oxide nanoparticles into single-walled carbon nanotubes (SWCNTs) to produce magnetic single-walled carbon nanotubes (mSWCNTs). Our objective is to bridge both nanotechnology and biofuel production by immobilizing the enzyme, Amyloglucosidase (AMG), onto mSWCNTs using physical adsorption and covalent immobilization, with the aim of recycling the immobilized enzyme, toward useful applications in biofuel production processes. We have demonstrated that the enzyme retains a certain percentage of its catalytic efficiency (up to 40%) in starch prototype biomass hydrolysis when used repeatedly (up to ten cycles) after immobilization on mSWCNTs, since the nanotubes can be easily separated from the reaction mixture using a simple magnet. The enzyme loading, activity, and structural changes after immobilization onto mSWCNTs were also studied. In addition, we have demonstrated that the immobilized enzyme retains its activity when stored at 4 °C for at least one month. These results, combined with the unique intrinsic properties of the nanotubes, pave the way for greater efficiency in carbon nanotube-enzyme bioreactors and reduced capital costs in industrial enzyme systems. PMID:23148719

Goh, Wei Jiang; Makam, Venkata S; Hu, Jun; Kang, Lifeng; Zheng, Minrui; Yoong, Sia Lee; Udalagama, Chammika N B; Pastorin, Giorgia

2012-12-11

72

Phosphorus-doped graphene and (8, 0) carbon nanotube: Structural, electronic, magnetic properties, and chemical reactivity  

NASA Astrophysics Data System (ADS)

Recently, doping non-carbon atoms into graphene or carbon nanotube (CNT) has attracted considerable attention due to its effectiveness to change or tailor their electronic and magnetic properties as well as chemical reactivity. In this work, we present a density functional theory study of the recently synthesized phosphorus (P) doped graphene and CNT. Particular attention is paid to studying the effects of P-doping on the structural, electronic, and magnetic properties as well as chemical reactivity of graphene or CNT. The results show that P dopant drastically changes the geometrical structure of graphene or CNT, rendering P and its neighboring C atoms protrude from the sidewall of CNT and graphene. Moreover, P-doping induces localized electronic states into graphene and CNTs, thus modifying the electronic properties by producing n-type behavior. Meanwhile, due to P doping, the graphene and CNT exhibit magnetic nature with spin net moment of 1.02 and 0.99 ?B, respectively. In order to evaluate the chemical reactivity of the two nanostructures, their interactions with several gas molecules, including NH3, H2O, O2, NO2, and NO, are further calculated. Our results may be useful not only for deeply understanding the properties of CNTs and graphenes, but also for developing various novel nanodevices.

Wang, Hong-mei; Wang, Hong-xia; Chen, Ying; Liu, Yue-jie; Zhao, Jing-xiang; Cai, Qing-hai; Wang, Xuan-zhang

2013-05-01

73

Covalent enzyme immobilization onto carbon nanotubes using a membrane reactor  

NASA Astrophysics Data System (ADS)

Composite porous polysulfone-carbon nanotubes membranes were prepared by dispersing carbon nanotubes into a polysulfone solution followed by the membrane formation by phase inversion-immersion precipitation technique. The carbon nanotubes with amino groups on surface were functionalized with different enzymes (carbonic anhydrase, invertase, diastase) using cyanuric chloride as linker between enzyme and carbon nanotube. The composite membrane was used as a membrane reactor for a better dispersion of carbon nanotubes and access to reaction centers. The membrane also facilitates the transport of enzymes to active carbon nanotubes centers for functionalization (amino groups). The functionalized carbon nanotubes are isolated by dissolving the membranes after the end of reaction. Carbon nanotubes with covalent immobilized enzymes are used for biosensors fabrications. The obtained membranes were characterized by Scanning Electron Microscopy, Thermal analysis, FT-IR Spectroscopy, Nuclear Magnetic Resonance, and functionalized carbon nanotubes were characterized by FT-IR spectroscopy.

Voicu, Stefan Ioan; Nechifor, Aurelia Cristina; Gales, Ovidiu; Nechifor, Gheorghe

2011-05-01

74

Low temperature magnetoresistance and magnetization studies of iron encapsulated multiwall carbon nanotube/polyvinyl chloride composites  

NASA Astrophysics Data System (ADS)

We present the experimental results of temperature dependent magnetoresistance (MR) and the magnetization studies of iron encapsulated multiwall carbon nanotube (MWCNT)/polyvinyl chloride (PVC) composites with different wt% of MWCNTs. Transmission electron microscopy characterization shows that MWCNTs are encapsulated with rod-shaped iron nanoparticles of aspect ratio of ~3. The MR behavior of 1.9 wt% MWCNT/PVC sample shows dominance of forward scattering and wave function shrinkage whereas, weak localization and electron-electron interactions explain the MR data of higher wt% samples (9.1, 16.6 and 44.4 wt%). The composites of 4.7 and 9.1 wt% exhibit ferromagnetic behavior at all temperatures with room temperature coercivities of ~1036 and 628 Oe, respectively.

Vasanthkumar, M. S.; Sameera, I.; Bhatia, Ravi; Prasad, V.; Jayanna, H. S.

2015-01-01

75

Carbon nanotube electronics  

Microsoft Academic Search

We evaluate the potential of carbon nanotubes (CNTs) as the basis for a new nanoelectronic technology. After briefly reviewing the electronic structure and transport properties of CNTs, we discuss the fabrication of CNT field-effect transistors (CNTFETs) formed from individual single-walled nanotubes (SWCNTs), SWCNT bundles, or multiwalled (MW) CNTs. The performance characteristics of the CNTFETs are discussed and compared to those

PHAEDON AVOURIS; JOERG APPENZELLER; RICHARD MARTEL; SHALOM J. WIND

2003-01-01

76

D{sup 0} magnetism in Ca doped narrow carbon nanotubes: First principle chirality effect study  

SciTech Connect

Curvature has always had crucial effects on the physical properties of narrow carbon nanotubes (CNTs) and here spin-polarized density functional calculations were employed to study electronic and magnetic properties of calcium-decorated narrow (5,5) and (9,0)CNTs with close diameters (?7?Å) and different chiralities. Our results showed that chirality had great impact on the electronic structure and magnetization of the doped CNTs. In addition, internally or externally doping of the calcium atoms was studied comparatively and although for the (9,0)CNT the internal doping was the most stable configuration, which involves a novel kind of spin-polarization originated from Ca-4s electrons, but for the (5,5)tube the external doping was the most stable one without any spin-polarization. On the other hand, calcium doping in the center of the (5,5)CNT was an endothermic process and led to the spin-polarization of unoccupied Ca-3d orbitals via direct exchange interaction between adjacent Ca atoms. In the considered systems, the existence of magnetization in the absence of any transition-metal elements was an example of valuable d{sup 0} magnetism title.

Hajiheidari, F.; Khoshnevisan, B., E-mail: b.khosh@kashanu.ac.ir [Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); Hashemifar, S. J. [Faculty of Physics, Isfahan University of technology, 84156-83111 Isfahan (Iran, Islamic Republic of)

2014-06-21

77

Transport in Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

This presentation discusses coupling between carbon nanotubes (CNT), simple metals (FEG) and a graphene sheet. The graphene sheet did not couple well with FEG, but the combination of a graphene strip and CNT did couple well with most simple metals.

Datta, S.; Xue, Yong-Qinag; Anantram, M. P.; Saini, Subhash (Technical Monitor)

1999-01-01

78

Carbon nanotubes: Perfect mismatch  

NASA Astrophysics Data System (ADS)

The electronic coupling between two stacked atomic layers is usually weak if their periodicities are incommensurate. Optical absorption experiments have now revealed unexpectedly strong interlayer coupling in incommensurate double-walled carbon nanotubes.

Dos Santos, João Lopes

2014-10-01

79

Carbon nanotubes: Fibrillar pharmacology  

NASA Astrophysics Data System (ADS)

The mechanisms by which chemically functionalized carbon nanotubes flow in blood and are excreted through the kidneys illustrate the unconventional behaviour of these fibrillar nanostructures, and the opportunities they offer as components for the design of advanced delivery vehicles.

Kostarelos, Kostas

2010-10-01

80

Laterally aligned, multiwalled carbon nanotube growth using Magnetospirillium magnetotacticum  

NASA Astrophysics Data System (ADS)

In this Letter, we report a straightforward method to produce multiwalled carbon nanotubes using magnetic nanoparticles of Magnetospirillium magnetotacticum as catalysts. Carbon nanotube growth on these nanoparticles resulted in multiwalled carbon nanotubes of an average diameter of 13nm showing a narrow distribution in diameter. The magnetic character of the iron-containing catalysts was exploited to generate biased growth orientations of the multiwalled carbon nanotubes during their synthesis. This magnetic bacteria-based synthetic approach represents a step forward towards synthesis-directed assembly of carbon nanotubes which is needed for easy integration of these materials into nanoelectronic devices.

Kumar, Nitin; Curtis, Wayne; Hahm, Jong-in

2005-04-01

81

Preparation, magnetic and electromagnetic properties of polyaniline/strontium ferrite/multiwalled carbon nanotubes composite  

NASA Astrophysics Data System (ADS)

Strontium ferrite particles were firstly prepared by sol-gel method and self-propagating synthesis, and then the polyaniline/strontium ferrite/multiwalled carbon nanotubes composites were synthesized through in situ polymerization approach. Structure, morphology and properties of the composite were characterized by various instruments. XRD analysis shows that the output of PANI increases with the increase of the content of MWCNTs, due to the large surface area of MWCNTs. Because of the coating of PANI, the outer diameter of MWCNTs increases from 10 nm to 20-40 nm. The electrical conductivity of the composites increases with the amount increase of MWCNTs and reaches 7.2196 S/cm in the presence of 2 g MWCNTs. The coercive force of the composites prepared with 2 g MWCNTs is 7457.17 Oe, which is much bigger than that of SrFe12O19 particles 6145.6 Oe, however, both the saturation magnetization and the remanent magnetization of the composite become much smaller than those of SrFe12O19 particles. The electromagnetic properties of the composite are excellent in the frequency range of 2-18 GHz, which mainly depend on the dielectric loss in the range of 2-9 GHz, and mainly on the magnetic loss in the range of 9-18 GHz.

Li, Yuqing; Huang, Ying; Qi, Shuhua; Niu, Lei; Zhang, Yinling; Wu, Yanfei

2012-02-01

82

Study of the thermo-magnetic fluctuations in carbon nano-tubes added Bi-2223 superconductors  

NASA Astrophysics Data System (ADS)

We have investigated the effect of addition of carbon nano-tubes (CNT) on the properties of Bi1.6Pb0.4Sr2Ca2Cu3Oy superconductors. The samples are prepared from commercial powders with addition of 0.1 wt% of CNT. They are characterized by XRD, SEM and magneto-resistivity in the transition region. As it was reported for CNT added Y-123 compounds, the refined cell parameters are practically independent of this kind of addition. Under applied magnetic field, a large broadening of resistive transition is observed. The dissipative behavior of resistivity can be explained using the well known expression, ?=?0(T/Tg-1)S. The modified vortex-glass to liquid transition theory is used to calculate the values of the glass-transition temperature Tg and the temperature and magnetic field dependent activation energy U0(B,T). These parameters are seen to decrease with CNT addition and applied magnetic field. Also, we have found that the undoped sample proves a better transition width, residual resistivity (?0) and a higher onset critical transition temperature of about 117.75 K. Also, the appearance of a double resistive transition for both samples is a confirmation of the existence of a secondary phase which plays the role of the weak links at the grain boundaries.

Saoudel, A.; Amira, A.; Boudjadja, Y.; Mahamdioua, N.; Amirouche, L.; Varilci, A.; Altintas, S. P.; Terzioglu, C.

2013-11-01

83

Functionalization of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2 or F2 or CnHm) is irradiated to provide a cold plasma of selected target species particles, such as atomic H or F, in a first chamber. The target species particles are d irected toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target species particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec. *Discrimination against non-target species is provided by (i) use of a target species having a lifetime that is much greater than a lifetime of a non-target species and/or (2) use of an applied magnetic field to discriminate between charged particle trajectories for target species and for non-target species.

Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

2009-01-01

84

Dynamics of multiple viscoelastic carbon nanotube based nanocomposites with axial magnetic field  

NASA Astrophysics Data System (ADS)

Nanocomposites and magnetic field effects on nanostructures have received great attention in recent years. A large amount of research work was focused on developing the proper theoretical framework for describing many physical effects appearing in structures on nanoscale level. Great step in this direction was successful application of nonlocal continuum field theory of Eringen. In the present paper, the free transverse vibration analysis is carried out for the system composed of multiple single walled carbon nanotubes (MSWCNT) embedded in a polymer matrix and under the influence of an axial magnetic field. Equivalent nonlocal model of MSWCNT is adopted as viscoelastically coupled multi-nanobeam system (MNBS) under the influence of longitudinal magnetic field. Governing equations of motion are derived using the Newton second low and nonlocal Rayleigh beam theory, which take into account small-scale effects, the effect of nanobeam angular acceleration, internal damping and Maxwell relation. Explicit expressions for complex natural frequency are derived based on the method of separation of variables and trigonometric method for the "Clamped-Chain" system. In addition, an analytical method is proposed in order to obtain asymptotic damped natural frequency and the critical damping ratio, which are independent of boundary conditions and a number of nanobeams in MNBS. The validity of obtained results is confirmed by comparing the results obtained for complex frequencies via trigonometric method with the results obtained by using numerical methods. The influence of the longitudinal magnetic field on the free vibration response of viscoelastically coupled MNBS is discussed in detail. In addition, numerical results are presented to point out the effects of the nonlocal parameter, internal damping, and parameters of viscoelastic medium on complex natural frequencies of the system. The results demonstrate the efficiency of the suggested methodology to find the closed form solutions for the free vibration response of multiple nanostructure systems under the influence of magnetic field.

Karli?i?, Danilo; Murmu, Tony; Caji?, Milan; Kozi?, Predrag; Adhikari, Sondipon

2014-06-01

85

Nitrogen in graphite and carbon nanotubes: Magnetism and mobility Yuchen Ma,* A. S. Foster, A. V. Krasheninnikov, and R. M. Nieminen  

E-print Network

Nitrogen in graphite and carbon nanotubes: Magnetism and mobility Yuchen Ma,* A. S. Foster, A. V November 2005 We use ab initio methods to study the atomic, electronic, and magnetic structure of nitrogen Incorporation of nitrogen into sp2 -hybridized carbon ma- terials has been shown to be a promising way to change

Krasheninnikov, Arkady V.

86

Carbon Nanotube Reinforced Polymer Nanocomposites  

E-print Network

Carbon Nanotube Reinforced Polymer Nanocomposites: Engineering the Interface at the Nano-Domain Wei Nanocomposites The Ideal "Straws" ­ Carbon Nanotubes 7.80.4208Steel 2.61501200MWCNT 1.341501054SWCNT Density (g on the surface of multi-walled carbon nanotubes are carried out using either a three-step chemical treatment

Southern California, University of

87

Carbon Nanotubes for Data Processing  

E-print Network

Carbon Nanotubes for Data Processing Joerg Appenzeller, T. J. Watson Research Center, IBM Research.2 Electronic Structure of Graphene 4 2.3 Electronic Structure of Carbon Nanotubes 4 2.4 Transport Properties 6 2.5 Contacts 9 3 Synthesis of Carbon Nanotubes 10 3.1 Synthetic Methods 10 3.2 Growth Mechanisms 12

Joselevich, Ernesto

88

Carbon Nanotube Linear Bearing Nanoswitches  

E-print Network

Carbon Nanotube Linear Bearing Nanoswitches V. V. Deshpande, H.-Y. Chiu, H. W. Ch. Postma, C. Miko-friction bearing capabilities of multiwalled carbon nanotubes (MWNTs) to realize nanoelectromechanical switches geometry remain important obstacles to the miniaturization of me- chanical systems. Carbon nanotubes

Bockrath, Marc

89

Sensitive and high-fidelity electrochemical immunoassay using carbon nanotubes coated with enzymes and magnetic nanoparticles.  

PubMed

We demonstrate a highly sensitive electrochemical immunosensor based on the combined use of substrate recycling and carbon nanotubes (CNTs) coated with tyrosinase (TYR) and magnetic nanoparticles (MNP). Both TYR and MNP were immobilized on the surface of CNTs by covalent attachment, followed by additional cross-linking via glutaraldehyde treatment to construct multi-layered cross-linked TYR-MNP aggregates (M-EC-CNT). Magnetically capturable, highly active and stable M-EC-CNT were further conjugated with primary antibody against a target analyte of hIgG, and used for a sandwich-type immunoassay with a secondary antibody conjugated with alkaline phosphatase (ALP). In the presence of a target analyte, a sensing assembly of M-EC-CNT and ALP-conjugated antibody was attracted onto a gold electrode using a magnet. On an electrode, ALP-catalyzed hydrolysis of phenyl phosphate generated phenol, and successive TYR-catalyzed oxidation of phenol produced electrochemically measurable o-quinone that was converted to catechol in a scheme of substrate recycling. Combination of highly active M-EC-CNT and substrate recycling for the detection of hIgG resulted in a sensitivity of 27.6 nA ng(-1) mL(-1) and a detection limit of 0.19 ng mL(-1) (1.2 pM), respectively, representing better performance than any other electrochemical immunosensors relying on the substrate recycling with the TYR-ALP combination. The present immunosensing system also displayed a long-term stability by showing a negligible loss of electrochemical detection signal even after reagents were stored in an aqueous buffer at 4°C for more than 6 months. PMID:21242086

Piao, Yunxian; Jin, Zongwen; Lee, Dohoon; Lee, Hye-Jin; Na, Hyon-Bin; Hyeon, Taeghwan; Oh, Min-Kyu; Kim, Jungbae; Kim, Hak-Sung

2011-03-15

90

Artifact properties of carbon nanotube yarn electrode in magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Objective. Deep brain stimulating (DBS) is a rapidly developing therapy that can treat many refractory neurological diseases. However, the traditional DBS electrodes which are made of Pt-Ir alloy may induce severe field distortions in magnetic resonance imaging (MRI) which leads to artifacts that will lower the local image quality and cause inconvenience or interference. A novel DBS electrode made from carbon nanotube yarns (CNTYs) is brought up to reduce the artifacts. This study is therefore to evaluate the artifact properties of the novel electrode. Approach. We compared its MR artifact characteristics with the Pt-Ir electrode in water phantom, including its artifact behaviors at different orientations as well as at various off-center positions, using both spin echo (SE) and gradient echo (GE) sequences, and confirmed its performance in vivo. Main results. The results in phantom showed that the CNTY electrode artifacts reduced as much as 62% and 74% on GE and SE images, respectively, compared to the Pt-Ir one. And consistent behaviors were confirmed in vivo. The susceptibility difference was identified as the dominant cause in producing artifacts. Significance. Employing the CNTY electrode may generate much less field distortion in the vicinity, improve local MR image quality and possibly be beneficial in various aspects.

Jiang, C. Q.; Hao, H. W.; Li, L. M.

2013-04-01

91

Transport Through Carbon Nanotube Wires  

NASA Technical Reports Server (NTRS)

This viewgraph presentation deals with the use of carbon nanotubes as a transport system. Contact, defects, tubular bend, phonons, and mechanical deformations all contribute to reflection within the nanotube wire. Bragg reflection, however, is native to an ideal energy transport system. Transmission resistance depends primarily on the level of energy present. Finally, the details regarding coupling between carbon nanotubes and simple metals are presented.

Anantram, M. P.; Kwak, Dochan (Technical Monitor)

2001-01-01

92

Facile synthesis of boronic acid-functionalized magnetic carbon nanotubes for highly specific enrichment of glycopeptides  

NASA Astrophysics Data System (ADS)

A stepwise strategy was developed to synthesize boronic acid functionalized magnetic carbon nanotubes (MCNTs) for highly specific enrichment of glycopeptides. The MCNTs were synthesized by a solvothermal reaction of Fe3+ loaded on the acid-treated CNTs and modified with 1-pyrenebutanoic acid N-hydroxysuccinimidyl ester (PASE) to bind aminophenylboronic acid (APBA) via an amide reaction. The introduction of PASE could bridge the MCNT and APBA, suppress the nonspecific adsorption and reduce the steric hindrance among the bound molecules. Due to the excellent structure of the MCNTs, the functionalization of PASE and then APBA on MCNTs was quite simple, specific and effective. The glycopeptides enrichment and separation with a magnetic field could be achieved by their reversible covalent binding with the boronic group of APBA-MCNTs. The exceptionally large specific surface area and the high density of boronic acid groups of APBA-MCNTs resulted in rapid and highly efficient enrichment of glycopeptides, even in the presence of large amounts of interfering nonglycopeptides. The functional MCNTs possessed high selectivity for enrichment of 21 glycopeptides from the digest of horseradish peroxidase demonstrated by MALDI-TOF mass spectrometric analysis showing more glycopeptides detected than the usual 9 glycopeptides with commercially available APBA-agarose. The proposed system showed better specificity for glycopeptides even in the presence of non-glycopeptides with 50 times higher concentration. The boronic acid functionalized MCNTs provide a promising selective enrichment platform for precise glycoproteomic analysis.A stepwise strategy was developed to synthesize boronic acid functionalized magnetic carbon nanotubes (MCNTs) for highly specific enrichment of glycopeptides. The MCNTs were synthesized by a solvothermal reaction of Fe3+ loaded on the acid-treated CNTs and modified with 1-pyrenebutanoic acid N-hydroxysuccinimidyl ester (PASE) to bind aminophenylboronic acid (APBA) via an amide reaction. The introduction of PASE could bridge the MCNT and APBA, suppress the nonspecific adsorption and reduce the steric hindrance among the bound molecules. Due to the excellent structure of the MCNTs, the functionalization of PASE and then APBA on MCNTs was quite simple, specific and effective. The glycopeptides enrichment and separation with a magnetic field could be achieved by their reversible covalent binding with the boronic group of APBA-MCNTs. The exceptionally large specific surface area and the high density of boronic acid groups of APBA-MCNTs resulted in rapid and highly efficient enrichment of glycopeptides, even in the presence of large amounts of interfering nonglycopeptides. The functional MCNTs possessed high selectivity for enrichment of 21 glycopeptides from the digest of horseradish peroxidase demonstrated by MALDI-TOF mass spectrometric analysis showing more glycopeptides detected than the usual 9 glycopeptides with commercially available APBA-agarose. The proposed system showed better specificity for glycopeptides even in the presence of non-glycopeptides with 50 times higher concentration. The boronic acid functionalized MCNTs provide a promising selective enrichment platform for precise glycoproteomic analysis. Electronic supplementary information (ESI) available: EDX spectra, MALDI-TOF MS and data summary. See DOI: 10.1039/c3nr05367a

Ma, Rongna; Hu, Junjie; Cai, Zongwei; Ju, Huangxian

2014-02-01

93

Optimization and evaluation of chelerythrine nanoparticles composed of magnetic multiwalled carbon nanotubes by response surface methodology  

NASA Astrophysics Data System (ADS)

In this study, a new chelerythrine nanomaterial targeted drug delivery system (Fe3O4/MWNTs-CHE) was designed with chelerythrine (CHE) as model of antitumor drug and magnetic multiwalled carbon nanotubes (Fe3O4/MWNTs) nanocomposites as drug carrier. The process and formulation variables of Fe3O4/MWNTs-CHE were optimized using response surface methodology (RSM) with a three-level, three-factor Box-Behnken design (BBD). Mathematical equations and response surface plots were used to relate the dependent and independent variables. The experimental results were fitted into second-order response surface model. When Fe3O4/MWNTs:CHE ratio was 20.6:1, CHE concentration was 172.0 ?g/mL, temperature was 34.5 °C, the drug loading content and entrapment efficiency were 3.04 ± 0.17% and 63.68 ± 2.36%, respectively. The optimized Fe3O4/MWNTs-CHE nanoparticles were characterized by scanning electron microscopy (SEM), Zeta potential, in vitro drug release and MTT assays. The in vitro CHE drug release behavior from Fe3O4/MWNTs-CHE displayed a biphasic drug release pattern and followed Korsmeyer-Peppas model with Fickian diffusion mechanism for drug release. The results from MTT assays suggested that the Fe3O4/MWNTs-CHE could effectively inhibit the proliferation of human hepatoma cells (HepG2), which displayed time or concentration-dependent manner. All these preliminary studies were expected to provide a theoretical basis and offer new methods for preparation efficient magnetic targeted drug delivery systems.

Huang, Yong; Yuan, Yulin; Zhou, Zhide; Liang, Jintao; Chen, Zhencheng; Li, Guiyin

2014-02-01

94

Carbon nanotube filters.  

PubMed

Over the past decade of nanotube research, a variety of organized nanotube architectures have been fabricated using chemical vapour deposition. The idea of using nanotube structures in separation technology has been proposed, but building macroscopic structures that have controlled geometric shapes, density and dimensions for specific applications still remains a challenge. Here we report the fabrication of freestanding monolithic uniform macroscopic hollow cylinders having radially aligned carbon nanotube walls, with diameters and lengths up to several centimetres. These cylindrical membranes are used as filters to demonstrate their utility in two important settings: the elimination of multiple components of heavy hydrocarbons from petroleum-a crucial step in post-distillation of crude oil-with a single-step filtering process, and the filtration of bacterial contaminants such as Escherichia coli or the nanometre-sized poliovirus ( approximately 25 nm) from water. These macro filters can be cleaned for repeated filtration through ultrasonication and autoclaving. The exceptional thermal and mechanical stability of nanotubes, and the high surface area, ease and cost-effective fabrication of the nanotube membranes may allow them to compete with ceramic- and polymer-based separation membranes used commercially. PMID:15286755

Srivastava, A; Srivastava, O N; Talapatra, S; Vajtai, R; Ajayan, P M

2004-09-01

95

The Toxicology of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

1. Carbon nanotube structure, synthesis and applications C. Singh and W. Song; 2. The aerodynamic behaviour and pulmonary deposition of carbon nanotubes A. Buckley, R. Smith and R Maynard; 3. Utilising the concept of the biologically effective dose to define the particle and fibre hazards of carbon nanotubes K. Donaldson, R. Duffin, F. Murphy and C. Poland; 4. CNT, biopersistence and the fibre paradigm D. Warheit and M. DeLorme; 5. Length-dependent retention of fibres in the pleural space C. Poland, F. Murphy and K. Donaldson; 6. Experimental carcinogenicity of carbon nanotubes in the context of other fibres K. Unfried; 7. Fate and effects of carbon nanotubes following inhalation J. Ryman-Rasmussen, M. Andersen and J. Bonner; 8. Responses to pulmonary exposure to carbon nanotubes V. Castranova and R. Mercer; 9. Genotoxicity of carbon nanotubes R. Schins, C. Albrecht, K. Gerloff and D. van Berlo; 10. Carbon nanotube-cellular interactions; macrophages, epithelial and mesothelial cells V. Stone, M. Boyles, A. Kermanizadeh, J. Varet and H. Johnston; 11. Systemic health effects of carbon nanotubes following inhalation J. McDonald; 12. Dosimetry and metrology of carbon nanotubes L. Tran, L. MacCalman and R. Aitken; Index.

Donaldson, Ken; Poland, Craig; Duffin, Rodger; Bonner, James

2012-06-01

96

Stable confinement of positron emission tomography and magnetic resonance agents within carbon nanotubes for bimodal imaging  

PubMed Central

Aims Simultaneous positron emission tomography/MRI has recently been introduced to the clinic and dual positron emission tomography/MRI probes are rare and of growing interest. We have developed a strategy for producing multimodal probes based on a carbon nanotube platform without the use of chelating ligands. Materials & methods Gd3+ and 64Cu2+ ions were loaded into ultra-short single-walled carbon nanotubes by sonication. Normal, tumor-free athymic nude mice were injected intravenously with the probe and imaged over 48 h. Results & conclusion The probe was stable for up to 24 h when challenged with phosphate-buffered saline and mouse serum. Positron emission tomography imaging also confirmed the stability of the probe in vivo for up to 48 h. The probe was quickly cleared from circulation, with enhanced accumulation in the lungs. Stable encapsulation of contrast agents within ultra-short single-walled carbon nanotubes represents a new strategy for the design of advanced imaging probes with variable multimodal imaging capabilities. PMID:24628687

Cisneros, Brandon T; Law, Justin J; Matson, Michael L; Azhdarinia, Ali; Sevick-Muraca, Eva M; Wilson, Lon J

2014-01-01

97

Boron and Nitrogen Doped Single walled Carbon Nanotubes as Possible Dilute Magnetic Semiconductors  

PubMed Central

The structure of single walled armchair and zig-zag carbon nanotubes having 70 atoms and two carbons replaced by boron or nitrogen is obtained at minium energy using HF/6-31G* molecular orbital theory. The calculations show that the ground state of the zig-zag tubes is a triplet state while for the armchair tubes it is a singlet. In the zig-zag tubes the density of states at the Fermi level is greater for the spin down states compared to the spin up state indicating that the doped tubes could be ferromagnetic.

2007-01-01

98

Carbon nanotubes on a substrate  

DOEpatents

The present invention includes carbon nanotubes whose hollow cores are 100% filled with conductive filler. The carbon nanotubes are in uniform arrays on a conductive substrate and are well-aligned and can be densely packed. The uniformity of the carbon nanotube arrays is indicated by the uniform length and diameter of the carbon nanotubes, both which vary from nanotube to nanotube on a given array by no more than about 5%. The alignment of the carbon nanotubes is indicated by the perpendicular growth of the nanotubes from the substrates which is achieved in part by the simultaneous growth of the conductive filler within the hollow core of the nanotube and the densely packed growth of the nanotubes. The present invention provides a densely packed carbon nanotube growth where each nanotube is in contact with at least one nearest-neighbor nanotube. The substrate is a conductive substrate coated with a growth catalyst, and the conductive filler can be single crystals of carbide formed by a solid state reaction between the substrate material and the growth catalyst. The present invention further provides a method for making the filled carbon nanotubes on the conductive substrates. The method includes the steps of depositing a growth catalyst onto the conductive substrate as a prepared substrate, creating a vacuum within a vessel which contains the prepared substrate, flowing H2/inert (e.g. Ar) gas within the vessel to increase and maintain the pressure within the vessel, increasing the temperature of the prepared substrate, and changing the H2/Ar gas to ethylene gas such that the ethylene gas flows within the vessel. Additionally, varying the density and separation of the catalyst particles on the conductive substrate can be used to control the diameter of the nanotubes.

Gao, Yufei [Kennewick, WA; Liu, Jun [West Richland, WA

2002-03-26

99

Carbon nanotube core graphitic shell hybrid fibers.  

PubMed

A carbon nanotube yarn core graphitic shell hybrid fiber was fabricated via facile heat treatment of epoxy-based negative photoresist (SU-8) on carbon nanotube yarn. The effective encapsulation of carbon nanotube yarn in carbon fiber and a glassy carbon outer shell determines their physical properties. The higher electrical conductivity (than carbon fiber) of the carbon nanotube yarn overcomes the drawbacks of carbon fiber/glassy carbon, and the better properties (than carbon nanotubes) of the carbon fiber/glassy carbon make up for the lower thermal and mechanical properties of the carbon nanotube yarn via synergistic hybridization without any chemical doping and additional processes. PMID:24224730

Hahm, Myung Gwan; Lee, Jae-Hwang; Hart, Amelia H C; Song, Sung Moo; Nam, Jaewook; Jung, Hyun Young; Hashim, Daniel Paul; Li, Bo; Narayanan, Tharangattu N; Park, Chi-Dong; Zhao, Yao; Vajtai, Robert; Kim, Yoong Ahm; Hayashi, Takuya; Ku, Bon-Cheol; Endo, Morinobu; Barrera, Enrique; Jung, Yung Joon; Thomas, Edwin L; Ajayan, Pulickel M

2013-12-23

100

Preparation of novel curcumin-imprinted polymers based on magnetic multi-walled carbon nanotubes for the rapid extraction of curcumin from ginger powder and kiwi fruit root.  

PubMed

A novel molecularly imprinted polymer based on magnetic phenyl-modified multi-walled carbon nanotubes was synthesized using curcumin as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. The phenyl groups contained in the magnetic imprinted polymers acted as the assisting functional monomer. The magnetic imprinted polymers were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy and vibrating sample magnetometry. Adsorption studies demonstrated that the magnetic imprinted polymers possessed excellent selectivity toward curcumin with a maximum capacity of 16.80 mg/g. Combining magnetic extraction and high-performance liquid chromatography technology, the magnetic imprinted polymer based on magnetic phenyl-modified multi-walled carbon nanotubes was applied for the rapid separation and enrichment of curcumin from ginger powder and kiwi fruit root successfully. PMID:25358961

Zhang, Zhaohui; Chen, Xing; Rao, Wei; Long, Fang; Yan, Liang; Yin, Yuli

2015-01-01

101

Carbon nanotube network varactor  

NASA Astrophysics Data System (ADS)

Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling.

Generalov, A. A.; Anoshkin, I. V.; Erdmanis, M.; Lioubtchenko, D. V.; Ovchinnikov, V.; Nasibulin, A. G.; Räisänen, A. V.

2015-01-01

102

Carbon nanotube network varactor.  

PubMed

Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling. PMID:25556375

Generalov, A A; Anoshkin, I V; Erdmanis, M; Lioubtchenko, D V; Ovchinnikov, V; Nasibulin, A G; Räisänen, A V

2015-01-30

103

Carbon nanotube electronics  

Microsoft Academic Search

Presents experimental results on single-wall carbon nanotube field-effect transistors (CNFETs) operating at gate and drain voltages below 1V. Taking into account the extremely small diameter of the semiconducting tubes used as active components, electrical characteristics are comparable with state-of-the-art metal oxide semiconductor field-effect transistors (MOSFETs). While output as well as subthreshold characteristics resemble those of conventional MOSFETs, we find that

J. Appenzeller; J. Knoch; R. Martel; V. Derycke; S. J. Wind; P. Avouris

2002-01-01

104

Thermoelectric power in carbon nanotubes  

SciTech Connect

The theoretical results for the temperature dependence of the thermoelectric power of graphite and semimetal carbon nanotubes are reported. In the calculations, the cylindrical superatomic range structure of nanotubes is taken into account. The Boltzmann equation and the {pi}-electron model of semimetal carbon nanotubes are used. The basic parameters of the calculation are the concentration of electrons, the Fermi energy, and the energy of the local level associated with the cylindrical structure of carbon nanotubes. The theoretical results are compared with the available experimental data.

Mavrinskiy, A. V., E-mail: mavrinsky@gmail.com; Baitinger, E. M. [Chelyabinsk State Pedagogical University (Russian Federation)

2009-04-15

105

CARBON NANOTUBES AS MULTIPOLLUTANT SORBENTS  

EPA Science Inventory

Exploratory Research Program Project - Carbon nanotubes (CNTs) are formed from graphite (or graphene) sheets rolled into tubes, typically with diameters of 1 - 10 nm and lengths of 200 - 500 nm. Carbon nanotubes have unique electrical properties that have led to interest in thei...

106

CARBON NANOTUBE TRANSISTORS: AN EVALUATION  

E-print Network

CARBON NANOTUBE TRANSISTORS: AN EVALUATION L.C. Castro, D.L. John, and D.L. Pulfrey Department-effect transistors. It is shown that, by appropriate work function engineering of the source, drain and gate contacts-effect transistors, nanotechnology 1. INTRODUCTION Carbon nanotube molecules can be either metallic or semiconducting

Pulfrey, David L.

107

Carbon nanotube actuators  

PubMed

Electromechanical actuators based on sheets of single-walled carbon nanotubes were shown to generate higher stresses than natural muscle and higher strains than high-modulus ferroelectrics. Like natural muscles, the macroscopic actuators are assemblies of billions of individual nanoscale actuators. The actuation mechanism (quantum chemical-based expansion due to electrochemical double-layer charging) does not require ion intercalation, which limits the life and rate of faradaic conducting polymer actuators. Unlike conventional ferroelectric actuators, low operating voltages of a few volts generate large actuator strains. Predictions based on measurements suggest that actuators using optimized nanotube sheets may eventually provide substantially higher work densities per cycle than any previously known technology. PMID:10334985

Baughman; Cui; Zakhidov; Iqbal; Barisci; Spinks; Wallace; Mazzoldi; De Rossi D; Rinzler; Jaschinski; Roth; Kertesz

1999-05-21

108

Protonation of carbon single-walled nanotubes studied using 13C and 1H-13C cross polarization nuclear magnetic resonance and Raman spectroscopies.  

PubMed

The reversible protonation of carbon single-walled nanotubes (SWNTs) in sulfuric acid and Nafion was investigated using solid-state nuclear magnetic resonance (NMR) and Raman spectroscopies. Magic-angle spinning (MAS) was used to obtain high-resolution 13C and 1H-13C cross polarization (CP) NMR spectra. The 13C NMR chemical shifts are reported for bulk SWNTs, H2SO4-treated SWNTs, SWNT-Nafion polymer composites, SWNT-AQ55 polymer composites, and SWNTs in contact with water. Protonation occurs without irreversible oxidation of the nanotube substrate via a charge-transfer process. This is the first report of a chemically induced change in a SWNT 13C resonance brought about by a reversible interaction with an acidic proton, providing additional evidence that carbon nanotubes behave as weak bases. Cross polarization was found to be a powerful technique for providing an additional contrast mechanism for studying nanotubes in contact with other chemical species. The CP studies confirmed polarization transfer from nearby protons to nanotube carbon atoms. The CP technique was also applied to investigate water adsorbed on carbon nanotube surfaces. Finally, the degree of bundling of the SWNTs in Nafion films was probed with the 1H-13C CP-MAS technique. PMID:16332107

Engtrakul, Chaiwat; Davis, Mark F; Gennett, Thomas; Dillon, Anne C; Jones, Kim M; Heben, Michael J

2005-12-14

109

Superconducting properties of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Metallic single wall carbon nanotubes have attracted much interest as 1D quantum wires combining a low carrier density and a high mobility. It was believed for a long time that low temperature transport was exclusively dominated by the existence of unscreened Coulomb interactions leading to an insulating behavior at low temperature. However experiments have also shown evidence of superconductivity in carbon nanotubes. We distinguish two fundamentally different physical situations. When carbon nanotubes are connected to superconducting electrodes, they exhibit proximity induced superconductivity with supercurrents which strongly depend on the transmission of the electrodes. On the other hand intrinsic superconductivity was also observed in suspended ropes of carbon nanotubes and recently in doped individual tubes. These experiments indicate the presence of attractive interactions in carbon nanotubes which overcome Coulomb repulsion at low temperature, and enables investigation of superconductivity in a 1D limit never explored before. To cite this article: M. Ferrier et al., C. R. Physique 10 (2009).

Ferrier, M.; Kasumov, A.; Deblock, R.; Guéron, S.; Bouchiat, H.

2009-05-01

110

Effects of Magnetic Field and Gravity on Single-Walled Carbon Nanotube Production in Three Directions of Arc Discharge Current  

NASA Astrophysics Data System (ADS)

The effects of the discharge current direction with respect to gravity and a steady magnetic field on the production of single-walled carbon nanotubes (SWNTs) by the arc discharge method are examined. In the experiment, highly dense electrons in the arc plasma collide with He gas atoms at a frequency of ~3.5 × 1011 Hz, and the electron energy is effectively transferred to the gas atoms to accelerate them to a speed greater than that of the natural heat convection. The production rate of soot changes with the direction of the discharge current. When a magnetic field is applied, electrons in the arc plasma are accelerated in the J × B direction by the Lorentz force, resulting in an increase in the production rate of soot and the efficiency of SWNT production.

Jellur Rahman, Mohammad; Mieno, Tetsu

111

Single-Walled Carbon Nanotubes for Nanoelectronics  

E-print Network

CHAPTER 6 Single-Walled Carbon Nanotubes for Nanoelectronics M. S. Fuhrer UNIVERSITY OF MARYLAND . . . . . . . . . . . . 299 1. Synthesis of Single-Walled Carbon Nanotubes . . . . . . . . . . . . . 299 2. Fabrication 1991) (``multi-walled carbon nanotubes'' or MWNTs). Soon thereafter, single-walled carbon nanotubes

Rubloff, Gary W.

112

Silicon Encapsulated Carbon Nanotubes  

PubMed Central

A dual stage process of depositing bamboo-like carbon nanotubes (BCNTs) by hot filament chemical vapor deposition (HFCVD) and coating Si using Radio frequency sputtering (RFS) technique. The films were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron field emission studies (EFE). SEM results suggest a dense network of homogeneous silicon-coated BCNTs. From the comprehensive analysis of the results provided by these techniques emerges the picture of Si encapsulated BCNTs. PMID:20652067

2010-01-01

113

Functionalization of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2, or F2, or CnHm) is irradiated to provide a cold plasma of selected target particles, such as atomic H or F, in a first chamber. The target particles are directed toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec.

Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

2007-01-01

114

Functionalization of carbon nanotubes  

NASA Technical Reports Server (NTRS)

Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H.sub.2 or F.sub.2 or C.sub.nH.sub.m) is irradiated to provide a cold plasma of selected target particles, such as atomic H or F, in a first chamber. The target particles are directed toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec.

Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

2007-01-01

115

Continuous carbon nanotube reinforced composites.  

PubMed

Carbon nanotubes are considered short fibers, and polymer composites with nanotube fillers are always analogues of random, short fiber composites. The real structural carbon fiber composites, on the other hand, always contain carbon fiber reinforcements where fibers run continuously through the composite matrix. With the recent optimization in aligned nanotube growth, samples of nanotubes in macroscopic lengths have become available, and this allows the creation of composites that are similar to the continuous fiber composites with individual nanotubes running continuously through the composite body. This allows the proper utilization of the extreme high modulus and strength predicted for nanotubes in structural composites. Here, we fabricate such continuous nanotube polymer composites with continuous nanotube reinforcements and report that under compressive loadings, the nanotube composites can generate more than an order of magnitude improvement in the longitudinal modulus (up to 3,300%) as well as damping capability (up to 2,100%). It is also observed that composites with a random distribution of nanotubes of same length and similar filler fraction provide three times less effective reinforcement in composites. PMID:18680351

Ci, L; Suhr, J; Pushparaj, V; Zhang, X; Ajayan, P M

2008-09-01

116

Solvothermal synthesis of cobalt ferrite nanoparticles loaded on multiwalled carbon nanotubes for magnetic resonance imaging and drug delivery.  

PubMed

Multiwalled carbon nanotube (MWCNT)/cobalt ferrite (CoFe(2)O(4)) magnetic hybrids were synthesized by a solvothermal method. The reaction temperature significantly affected the structure of the resultant MWCNT/CoFe(2)O(4) hybrids, which varied from 6nm CoFe(2)O(4) nanoparticles uniformly coated on the nanotubes at 180°C to agglomerated CoFe(2)O(4) spherical particles threaded by MWCNTs and forming necklace-like nanostructures at 240°C. Based on the superparamagnetic property at room temperature and high hydrophilicity, the MWCNT/CoFe(2)O(4) hybrids prepared at 180°C (MWCNT/CoFe(2)O(4)-180) were further investigated for biomedical applications, which showed a high T(2) relaxivity of 152.8 Fe mM(-1)s(-1) in aqueous solutions, a significant negative contrast enhancement effect on cancer cells and, more importantly, low cytotoxicity and negligible hemolytic activity. The anticancer drug doxorubicin (DOX) can be loaded onto the hybrids and subsequently released in a sustained and pH-responsive way. The DOX-loaded hybrids exhibited notable cytotoxicity to HeLa cancer cells due to the intracellular release of DOX. These results suggest that MWCNT/CoFe(2)O(4)-180 hybrids may be used as both effective magnetic resonance imaging contrast agents and anticancer drug delivery systems for simultaneous cancer diagnosis and chemotherapy. PMID:21664499

Wu, Huixia; Liu, Gang; Wang, Xue; Zhang, Jiamin; Chen, Yu; Shi, Jianlin; Yang, Hong; Hu, He; Yang, Shiping

2011-09-01

117

Oblique incidence scattering from single-walled carbon nanotubes  

SciTech Connect

A theory of electromagnetic wave scattering by metallic single-walled carbon nanotubes at oblique incidence is provided using modal techniques. Electronic excitations on the nanotube's surface are modeled by an infinitesimally thin layer of free-electron gas described previously by means of the linearized fluid theory. The current induced on the surface of the nanotube and the echo width of both transverse magnetic and transverse electric uniform plane wave by system at oblique incidences is obtained. Numerical results show that the optical wave scattering by carbon nanotubes strongly depends on the nanotube's radius and angle of incidence wave with system.

Moradi, Afshin [Department of Nano Science, Kermanshah University of Technology, 67178-63766 Kermanshah, Iran and Department of Nano Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), 19395-5531 Tehran (Iran, Islamic Republic of)

2010-03-15

118

Impact of carbondiimide crosslinker used for magnetic carbon nanotube mediated GFP plasmid delivery  

NASA Astrophysics Data System (ADS)

1-ethyl-3-(3-dimethylaminopropyl) carbondiimide hydrochloride (EDC) is commonly used as a crosslinker to help bind biomolecules, such as DNA plasmids, with nanostructures. However, EDC often remains, after a crosslink reaction, in the micro-aperture of the nanostructure, e.g., carbon nanotube. The remaining EDC shows positive green fluorescent signals and makes a nanostructure with a strong cytotoxicity which induces cell death. The toxicity of EDC was confirmed on a breast cancer cell line (MCF-7) and two leukemic cell lines (THP-1 and KG-1). The MCF-7 cells mainly underwent necrosis after treatment with EDC, which was verified by fluorescein isothiocyanate (FITC) annexin V staining, video microscopy and scanning electronic microscopy (SEM). If the EDC was not removed completely, the nanostructures with remaining EDC produced a green fluorescent background that could interfere with flow cytometry (FACS) measurement and result in false information about GFP plasmid delivery. Effective methods to remove residual EDC on macromolecules were also developed.

Hao, Yuzhi; Xu, Peng; He, Chuan; Yang, Xiaoyan; Huang, Min; Xing, James; Chen, Jie

2011-07-01

119

Carbon nanotube array actuators  

NASA Astrophysics Data System (ADS)

Experimental investigations of highly vertically aligned carbon nanotubes (CNTs), also known as CNT-arrays, are the main focus of this paper. The free strain as result of an active material behavior is analyzed via a novel experimental setup. Previous test experiences of papers made of randomly oriented CNTs, also called Bucky-papers, reveal comparably low free strain. The anisotropy of aligned CNTs promises better performance. Via synthesis techniques like chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), highly aligned arrays of multi-walled carbon nanotubes (MWCNTs) are synthesized. Two different types of CNT-arrays are analyzed, morphologically first, and optically tested for their active characteristics afterwards. One type of the analyzed arrays features tube lengths of 750-2000 ?m with a large variety of diameters between 20 and 50 nm and a wave-like CNT-shape. The second type features a maximum, almost uniform, length of 12 ?m and a constant diameter of 50 nm. Different CNT-lengths and array types are tested due to their active behavior. As result of the presented tests, it is reported that the quality of orientation is the most decisive property for excellent active behavior. Due to their alignment, CNT-arrays feature the opportunity to clarify the actuation mechanism of architectures made of CNTs.

Geier, S.; Mahrholz, T.; Wierach, P.; Sinapius, M.

2013-09-01

120

Mechanical properties of carbon nanotubes  

Microsoft Academic Search

A variety of outstanding experimental results on the elucidation of the elastic properties of carbon nanotubes are fast appearing. These are based mainly on the techniques of high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM) to determine the Young's moduli of single-wall nanotube bundles and multi-walled nanotubes, prepared by a number of methods. These results are confirming the

J.-P. Salvetat; J.-M. Bonard; N. H. Thomson; A. J. Kulik; L. Forró; W. Benoit; L. Zuppiroli

1999-01-01

121

Carbon fibers modified with carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes were used to modify a polyacrylonitrile (PAN) polymer solution before the manufacture of the carbon fiber\\u000a precursor. The modified PAN fibers were spun from a dimethylformamide solution containing a small amount of single-walled\\u000a carbon nanotubes. The fibers were characterized by thermogravimetry and optical and scanning electron microscopy. Structure,\\u000a morphology, and selected properties of the composite polymeric fibers and

Aneta Fraczek-Szczypta; Maciej Bogun; Stanislaw Blazewicz

2009-01-01

122

Carbon nanotubes in hyperthermia therapy  

PubMed Central

Thermal tumor ablation therapies are being developed with a variety of nanomaterials, including single-and multiwalled carbon nanotubes. Carbon nanotubes (CNTs) have attracted interest due to their potential for simultaneous imaging and therapy. In this review, we highlight in vivo applications of carbon nanotube-mediated thermal therapy (CNMTT) and examine the rationale for use of this treatment in recurrent tumors or those resistant to conventional cancer therapies. Additionally, we discuss strategies to localize and enhance the cancer selectivity of this treatment and briefly examine issues relating the toxicity and long term fate of CNTs. PMID:23933617

Singh, Ravi; Torti, Suzy V.

2013-01-01

123

Method for producing carbon nanotubes  

DOEpatents

Method for producing carbon nanotubes. Carbon nanotubes were prepared using a low power, atmospheric pressure, microwave-generated plasma torch system. After generating carbon monoxide microwave plasma, a flow of carbon monoxide was directed first through a bed of metal particles/glass beads and then along the outer surface of a ceramic tube located in the plasma. As a flow of argon was introduced into the plasma through the ceramic tube, ropes of entangled carbon nanotubes, attached to the surface of the tube, were produced. Of these, longer ropes formed on the surface portion of the tube located in the center of the plasma. Transmission electron micrographs of individual nanotubes revealed that many were single-walled.

Phillips, Jonathan (Santa Fe, NM); Perry, William L. (Jemez Springs, NM); Chen, Chun-Ku (Albuquerque, NM)

2006-02-14

124

Microwave characterisation of carbon nanotube powders  

PubMed Central

We have used a 3-GHz microwave host cavity to study the remarkable electronic properties of metallic, single-walled carbon nanotubes. Powder samples are placed in its magnetic field antinode, which induces microwave currents without the need for electrical contacts. Samples are shown to screen effectively the microwave magnetic field, implying an extremely low value of sheet resistance (< 10 ??) within the graphene sheets making up the curved nanotube walls. Associated microwave losses are large due to the large surface area, and also point to a similar, very small value of sheet resistance due to the inherent ballistic electron transport. PMID:22849959

2012-01-01

125

Carbon Nanotube Electronics  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) can be used to build field effect transistors (CNTFETs). Early devices had marginal characteristics due to their large contact resistances. By improving the contacts and utilizing top-gates with thin oxides, we produced CNFETs with characteristics better than those of silicon devices. CNTFETs with as-grown CNTs are invariably p-type. We discuss two methods for p-to-n conversion: a) doping of p-type devices, b) annealing in vacuum to remove adsorbed oxygen. A comparison of these methods shows fundamental differences in the mechanisms of p-to-n- conversion. The key effect of oxygen adsorption is not to dope the tubes, but to modify the barriers at the contacts. A method for controlling these contact barriers will be demonstrated. Having both p-type and n-type CNTFETs we were able to fabricate complementary logic gates. Two types of NOT gates will be presented: an inter-molecular and an intra-molecular. Finally, we will discuss the fabrication of CNTFETs using CNTs bundles containing both metallic and semiconducting CNTs without first removing the metallic nanotubes. Collaborators: J. Appenzeller, P. G. Collins, V. Derycke, R. Martel, and S. Wind.

Avouris, Phaedon

2002-03-01

126

Emerging Applications of Carbon Nanotubes  

E-print Network

On the basis of their unique electrical and mechanical properties, carbon nanotubes (CNTs) have attracted great attention in recent years. A diverse array of methods has been developed to modify CNTs and to assemble them ...

Schnorr, Jan Markus

127

Carbon Nanotube-Nanocrystal Heterostructures  

SciTech Connect

The importance of generating carbon nanotube-nanoparticle heterostructures is that these composites ought to take advantage of and combine the unique physical and chemical properties of both carbon nanotubes and nanoparticles in one discrete structure. These materials have potential applicability in a range of diverse fields spanning heterogeneous catalysis to optoelectronic device development, of importance to chemists, physicists, materials scientists, and engineers. In this critical review, we present a host of diverse, complementary strategies for the reliable synthesis of carbon nanotube-nanoparticle heterostructures using both covalent as well as non-covalent protocols, incorporating not only single-walled and multi-walled carbon nanotubes but also diverse classes of metallic and semiconducting nanoparticles.

Peng, X.; Wong, S.

2009-04-01

128

Overview of Nanotechnology: Carbon Nanotubes  

NSDL National Science Digital Library

This overview of nanotechnology is presented by the NaMCATE project. Carbon nanotubes are "cylindrical molecules with a diameter as small as 1 nm and a length up to several millimeters. Consisting only of carbon atoms, they are cylinders made of a single layer of graphene." This lesson provides both an overview of nanotubes and a powerpoint presentation.Users must create a free login in order to access materials.

2011-09-21

129

Selective functionalization of carbon nanotubes  

NASA Technical Reports Server (NTRS)

The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.

Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H. (Inventor); Smalley, Richard E. (Inventor)

2009-01-01

130

Carbon nanotube terahertz detector.  

PubMed

Terahertz (THz) technologies are promising for diverse areas such as medicine, bioengineering, astronomy, environmental monitoring, and communications. However, despite decades of worldwide efforts, the THz region of the electromagnetic spectrum still continues to be elusive for solid state technology. Here, we report on the development of a powerless, compact, broadband, flexible, large-area, and polarization-sensitive carbon nanotube THz detector that works at room temperature. The detector is sensitive throughout the entire range of the THz technology gap, with responsivities as high as ?2.5 V/W and polarization ratios as high as ?5:1. Complete thermoelectric and opto-thermal characterization together unambiguously reveal the photothermoelectric origin of the THz photosignal, triggered by plasmonic absorption and collective antenna effects, and suggest that judicious design of thermal management and quantum engineering of Seebeck coefficients will lead to further enhancement of device performance. PMID:24875576

He, Xiaowei; Fujimura, Naoki; Lloyd, J Meagan; Erickson, Kristopher J; Talin, A Alec; Zhang, Qi; Gao, Weilu; Jiang, Qijia; Kawano, Yukio; Hauge, Robert H; Léonard, François; Kono, Junichiro

2014-07-01

131

Dragging human mesenchymal stem cells with the aid of supramolecular assemblies of single-walled carbon nanotubes, molecular magnets, and peptides in a magnetic field.  

PubMed

Human adipose-derived stem cells (hASCs) are an attractive cell source for therapeutic applicability in diverse fields for the repair and regeneration of damaged or malfunctioning tissues and organs. There is a growing number of cell therapies using stem cells due to their characteristics of modulation of immune system and reduction of acute rejection. So a challenge in stem cells therapy is the delivery of cells to the organ of interest, a specific site. The aim of this paper was to investigate the effects of a supramolecular assembly composed of single-walled carbon nanotubes (SWCNT), molecular magnets (lawsone-Co-phenanthroline), and a synthetic peptide (FWYANHYWFHNAFWYANHYWFHNA) in the hASCs cultures. The hASCs were isolated, characterized, expanded, and cultured with the SWCNT supramolecular assembly (SWCNT-MA). The assembly developed did not impair the cell characteristics, viability, or proliferation. During growth, the cells were strongly attached to the assembly and they could be dragged by an applied magnetic field of less than 0.3?T. These assemblies were narrower than their related allotropic forms, that is, multiwalled carbon nanotubes, and they could therefore be used to guide cells through thin blood capillaries within the human body. This strategy seems to be useful as noninvasive and nontoxic stem cells delivery/guidance and tracking during cell therapy. PMID:25688350

de Paula, Ana Cláudia C; Sáfar, Gustavo A M; Góes, Alfredo M; Bemquerer, Marcelo P; Ribeiro, Marcos A; Stumpf, Humberto O

2015-01-01

132

Dragging Human Mesenchymal Stem Cells with the Aid of Supramolecular Assemblies of Single-Walled Carbon Nanotubes, Molecular Magnets, and Peptides in a Magnetic Field  

PubMed Central

Human adipose-derived stem cells (hASCs) are an attractive cell source for therapeutic applicability in diverse fields for the repair and regeneration of damaged or malfunctioning tissues and organs. There is a growing number of cell therapies using stem cells due to their characteristics of modulation of immune system and reduction of acute rejection. So a challenge in stem cells therapy is the delivery of cells to the organ of interest, a specific site. The aim of this paper was to investigate the effects of a supramolecular assembly composed of single-walled carbon nanotubes (SWCNT), molecular magnets (lawsone-Co-phenanthroline), and a synthetic peptide (FWYANHYWFHNAFWYANHYWFHNA) in the hASCs cultures. The hASCs were isolated, characterized, expanded, and cultured with the SWCNT supramolecular assembly (SWCNT-MA). The assembly developed did not impair the cell characteristics, viability, or proliferation. During growth, the cells were strongly attached to the assembly and they could be dragged by an applied magnetic field of less than 0.3?T. These assemblies were narrower than their related allotropic forms, that is, multiwalled carbon nanotubes, and they could therefore be used to guide cells through thin blood capillaries within the human body. This strategy seems to be useful as noninvasive and nontoxic stem cells delivery/guidance and tracking during cell therapy.

de Paula, Ana Cláudia C.; Sáfar, Gustavo A. M.; Góes, Alfredo M.; Bemquerer, Marcelo P.; Ribeiro, Marcos A.; Stumpf, Humberto O.

2015-01-01

133

Preparation and characterization of multi-walled carbon nanotubes with nickel–phosphorous layers of high magnetic properties  

SciTech Connect

Highlights: ? Impurities in crude MWNTs were effectively removed after purification treatment. ? Many Ni nanoparticles were homogenously coated on the purified MWNTs. ? The saturation magnetization (Ms) of the MWNTs with Ni–P layers is 91.5 emu/g. -- Abstract: The multi-wall carbon nanotubes (MWNTs) with nickel–phosphorous (Ni–P) layers were prepared by electroless plating method. To obtain the MWNTs with Ni–P layers of high magnetic properties, an effective purification treatment and a pre-treatment procedure were developed. The crude MWNTs, the purified MWNTs and the MWNTs with Ni–P layers were characterized by scanning electron microscope (SEM)/energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). SEM results, TEM images and XRD results indicate that impurities in the crude MWNTs were effectively removed after the purification treatment and a large number of Ni nanoparticles were homogenously coated on the surface of the purified MWNTs. According to the VSM test, the saturation magnetization (Ms) of the MWNTs with Ni–P layers is 91.5 emu/g which is higher than results of other researchers.

Zhang, Yi, E-mail: zhangyi520love@yahoo.com.cn [Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi’an 710072 (China)] [Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi’an 710072 (China); Qi, Shuhua; Zhang, Fan [Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi’an 710072 (China)] [Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi’an 710072 (China)

2012-11-15

134

Impact of carbondiimide crosslinker used for magnetic carbon nanotube mediated GFP plasmid delivery.  

PubMed

1-Ethyl-3-(3-dimethylaminopropyl) carbondiimide hydrochloride (EDC) is commonly used as a crosslinker to help bind biomolecules, such as DNA plasmids, with nanostructures. However, EDC often remains, after a crosslink reaction, in the micro-aperture of the nanostructure, e.g., carbon nanotube. The remaining EDC shows positive green fluorescent signals and makes a nanostructure with a strong cytotoxicity which induces cell death. The toxicity of EDC was confirmed on a breast cancer cell line (MCF-7) and two leukemic cell lines (THP-1 and KG-1). The MCF-7 cells mainly underwent necrosis after treatment with EDC, which was verified by fluorescein isothiocyanate (FITC) annexin V staining, video microscopy and scanning electronic microscopy (SEM). If the EDC was not removed completely, the nanostructures with remaining EDC produced a green fluorescent background that could interfere with flow cytometry (FACS) measurement and result in false information about GFP plasmid delivery. Effective methods to remove residual EDC on macromolecules were also developed. PMID:21654030

Hao, Yuzhi; Xu, Peng; He, Chuan; Yang, Xiaoyan; Huang, Min; Xing, James; Chen, Jie

2011-07-15

135

Sharp Carbon-Nanotube Tips and Carbon-Nanotube Soldering Irons  

E-print Network

Sharp Carbon-Nanotube Tips and Carbon-Nanotube Soldering Irons By Abha Misra and Chiara Daraio for technological applications[1­4] and to form molecular junctions and inter- connections between carbon nanotubes interconnections between multiwalled carbon nanotubes (MWCNTs) that have dissimilar diameters. We report

Daraio, Chiara

136

Carbon nanotubes Growth of Single-Walled Carbon Nanotubes from Sharp  

E-print Network

Carbon nanotubes Growth of Single-Walled Carbon Nanotubes from Sharp Metal Tips Julio A. Rodri Banhart* The nucleation and growth of single-walled carbon nanotubes is observed in situ in a transmission a region of high surface curvature, spontaneous nucleation and growth of single-walled carbon nanotubes

Nordlund, Kai

137

Properties of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Different synthesizing methods are used to create various nanostructures of carbon; we are mainly interested in single and multi-wall carbon nanotubes, (SWCNTs) and (MWCNTs) respectively. The properties of these tubes are related to their synthetic methods, chirality, and diameter. The extremely sturdy structure of CNTs, with their distinct thermal and electromagnetic properties, suggests a tremendous use of these tubes in electronics and medicines. Here, we analyze various physical properties of SWCNTs with a special emphasis on electromagnetic and chemical properties. By examining their electrical properties, we demonstrate the viability of discrete CNT based components. After considering the advantages of using CNTs over microstructures, we make a case for the advancement and development of nanostructures based electronics. As for current CNT applications, it's hard to overlook their use and functionality in the development of cancer treatment. Whether the tubes are involved in chemotherapeutic drug delivery, molecular imaging and targeting, or photodynamic therapy, we show that the remarkable properties of SWCNTs can be used in advantageous ways by many different industries.

Masood, Samina; Bullmore, Daniel; Duran, Michael; Jacobs, Michael

2012-10-01

138

Carbon Nanotube Purification  

NASA Technical Reports Server (NTRS)

A method for cleaning or otherwise removing amorphous carbon and other residues that arise in growth of a carbon nanotube (CNT) array. The CNT array is exposed to a plurality of hydroxyls or hydrogen, produced from a selected vapor or liquid source such as H2O or H2O2. and the hydroxyls or hydrogen (neutral or electrically charged) react with the residues to produce partly or fully dissolved or hydrogenated or hydroxylizated products that can be removed or separated from the CNT array. The hydroxyls or hydrogen can be produced by heating the CNT array, residue and selected vapor or liquid source or by application of an electromagnetic excitation signal with a selected frequency or range of frequencies to dissociate the selected vapor or liquid. The excitation frequency can be chirped to cover a selected range of frequencies corresponding to dissociation of the selected vapor or liquid. Sonication may be uscd to supplement dissociation of the H2O and/or H2O2.

Delzeit, Lance D. (Inventor); Delzeit, Clement J. (Inventor)

2005-01-01

139

Carbon nanotube computer.  

PubMed

The miniaturization of electronic devices has been the principal driving force behind the semiconductor industry, and has brought about major improvements in computational power and energy efficiency. Although advances with silicon-based electronics continue to be made, alternative technologies are being explored. Digital circuits based on transistors fabricated from carbon nanotubes (CNTs) have the potential to outperform silicon by improving the energy-delay product, a metric of energy efficiency, by more than an order of magnitude. Hence, CNTs are an exciting complement to existing semiconductor technologies. Owing to substantial fundamental imperfections inherent in CNTs, however, only very basic circuit blocks have been demonstrated. Here we show how these imperfections can be overcome, and demonstrate the first computer built entirely using CNT-based transistors. The CNT computer runs an operating system that is capable of multitasking: as a demonstration, we perform counting and integer-sorting simultaneously. In addition, we implement 20 different instructions from the commercial MIPS instruction set to demonstrate the generality of our CNT computer. This experimental demonstration is the most complex carbon-based electronic system yet realized. It is a considerable advance because CNTs are prominent among a variety of emerging technologies that are being considered for the next generation of highly energy-efficient electronic systems. PMID:24067711

Shulaker, Max M; Hills, Gage; Patil, Nishant; Wei, Hai; Chen, Hong-Yu; Wong, H-S Philip; Mitra, Subhasish

2013-09-26

140

Deformation of carbon nanotubes in nanotube-polymer composites  

NASA Astrophysics Data System (ADS)

Composites of uniaxially oriented multiwalled carbon nanotubes embedded in polymer matrices were fabricated and investigated by transmission electron microscopy. In strained composite films, buckling was ubiquitously observed in bent nanotubes with large curvatures. By analyses of a large number of bent nanotubes, the onset buckling strain and fracture strain were estimated to be ?5% and ?18%, respectively. The buckling wavelengths are proportional to the dimensions of the nanotubes. Examination of the fracture surface showed adherence of the polymer to the nanotubes.

Bower, C.; Rosen, R.; Jin, L.; Han, J.; Zhou, O.

1999-05-01

141

Mechanics of deformation of carbon nanotubes  

E-print Network

The deformation mechanics of multi-walled carbon nanotubes (MWCNT) and vertically aligned carbon nanotube (VACNT) arrays were studied using analytical and numerical methods. An equivalent orthotropic representation (EOR) ...

Garg, Mohit, S.M. Massachusetts Institute of Technology

2005-01-01

142

Carbon Nanotube Based Molecular Electronics  

NASA Technical Reports Server (NTRS)

Carbon nanotubes and the nanotube heterojunctions have recently emerged as excellent candidates for nanoscale molecular electronic device components. Experimental measurements on the conductivity, rectifying behavior and conductivity-chirality correlation have also been made. While quasi-one dimensional simple heterojunctions between nanotubes with different electronic behavior can be generated by introduction of a pair of heptagon-pentagon defects in an otherwise all hexagon graphene sheet. Other complex 3- and 4-point junctions may require other mechanisms. Structural stability as well as local electronic density of states of various nanotube junctions are investigated using a generalized tight-binding molecular dynamics (GDBMD) scheme that incorporates non-orthogonality of the orbitals. The junctions investigated include straight and small angle heterojunctions of various chiralities and diameters; as well as more complex 'T' and 'Y' junctions which do not always obey the usual pentagon-heptagon pair rule. The study of local density of states (LDOS) reveal many interesting features, most prominent among them being the defect-induced states in the gap. The proposed three and four pointjunctions are one of the smallest possible tunnel junctions made entirely of carbon atoms. Furthermore the electronic behavior of the nanotube based device components can be taylored by doping with group III-V elements such as B and N, and BN nanotubes as a wide band gap semiconductor has also been realized in experiments. Structural properties of heteroatomic nanotubes comprising C, B and N will be discussed.

Srivastava, Deepak; Saini, Subhash; Menon, Madhu

1998-01-01

143

Optically encoded nanoprobes using single walled carbon nanotube as the building scaffold for magnetic field guided cell imaging.  

PubMed

We construct a novel fluorescent, surface enhanced Raman scattering (SERS) encoded and magnetic nanoprobe for live cell imaging. To fabricate this nanoprobe, single walled carbon nanotube (SWNT) is used as the building scaffold while gold nanoparticles (Au NPs), superparamagnetic iron oxide nanoparticles (SPIONs) and quantum dots (QDs) are employed as the building blocks. Here, Au NPs serve as the SERS substrate and QDs act as the fluorescent agent. Au NPs and SPIONs are first adsorbed on the SWNT via electrostatic interactions. Then a silica layer is coated on the SWNT. Finally, QDs are attached on the silica shell. With such a structure, various optical signals can be readily encoded to the nanoprobe simply by using different Raman molecules and QDs with different emission wavelengths. Experimental results show that the as-prepared nanoprobe exhibits well fluorescence and SERS performance. Furthermore, in vitro experiments demonstrate that the nanoprobe can fulfill magnetic field guided fluorescence and SERS dual mode imaging of live cells. As a fascinating optical encoding material and a multifunctional nanoplatform, the presented nanoprobe holds genuine potential in future biosensing applications. PMID:24401396

Wang, Hong; Wang, Zhuyuan; Ye, Minglang; Zong, Shenfei; Li, Mingyue; Chen, Peng; Ma, Xueqin; Cui, Yiping

2014-02-01

144

Multiscale Modeling with Carbon Nanotubes  

SciTech Connect

Technologically important nanomaterials come in all shapes and sizes. They can range from small molecules to complex composites and mixtures. Depending upon the spatial dimensions of the system and properties under investigation computer modeling of such materials can range from equilibrium and nonequilibrium Quantum Mechanics, to force-field-based Molecular Mechanics and kinetic Monte Carlo, to Mesoscale simulation of evolving morphology, to Finite-Element computation of physical properties. This brief review illustrates some of the above modeling techniques through a number of recent applications with carbon nanotubes: nano electromechanical sensors (NEMS), chemical sensors, metal-nanotube contacts, and polymer-nanotube composites.

Maiti, A

2006-02-21

145

Carbon Nanotubes as Cooper Pair Beam Dissertation  

E-print Network

Carbon Nanotubes as Cooper Pair Beam Splitters Dissertation to obtain the Doctoral Degree. Abstract We report on conductance measurements in carbon nanotube based double quan- tum dots connected% in the resonant case. Carbon Nanotubes ensure ballistic transport and long spin-flip scattering lengths. Due

Paris-Sud XI, Université de

146

CARBON NANOTUBE TRANSISTORS, SENSORS, AND A Dissertation  

E-print Network

CARBON NANOTUBE TRANSISTORS, SENSORS, AND BEYOND A Dissertation Presented to the Faculty of Philosophy by Xinjian Zhou January 2008 #12;#12;CARBON NANOTUBE TRANSISTORS, SENSORS, AND BEYOND Xinjian Zhou, Ph. D. Cornell University 2008 Carbon nanotubes are tiny hollow cylinders, made from a single

McEuen, Paul L.

147

Role of carbon nanotubes in electroanalytical chemistry  

Microsoft Academic Search

This review covers recent advances in the development of new designs of electrochemical sensors and biosensors that make use of electrode surfaces modification with carbon nanotubes. Applications based on carbon nanotubes-driven electrocatalytic effects, and the construction and analytical usefulness of new hybrid materials with polymers or other nanomaterials will be treated. Moreover, electrochemical detection using carbon nanotubes-modified electrodes as detecting

Lourdes Agüí; Paloma Yáñez-Sedeño; José M. Pingarrón

2008-01-01

148

EDITORIAL: Focus on Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

The study of carbon nanotubes, since their discovery by Iijima in 1991, has become a full research field with significant contributions from all areas of research in solid-state and molecular physics and also from chemistry. This Focus Issue in New Journal of Physics reflects this active research, and presents articles detailing significant advances in the production of carbon nanotubes, the study of their mechanical and vibrational properties, electronic properties and optical transitions, and electrical and transport properties. Fundamental research, both theoretical and experimental, represents part of this progress. The potential applications of nanotubes will rely on the progress made in understanding their fundamental physics and chemistry, as presented here. We believe this Focus Issue will be an excellent guide for both beginners and experts in the research field of carbon nanotubes. It has been a great pleasure to edit the many excellent contributions from Europe, Japan, and the US, as well from a number of other countries, and to witness the remarkable effort put into the manuscripts by the contributors. We thank all the authors and referees involved in the process. In particular, we would like to express our gratitude to Alexander Bradshaw, who invited us put together this Focus Issue, and to Tim Smith and the New Journal of Physics staff for their extremely efficient handling of the manuscripts. Focus on Carbon Nanotubes Contents <;A article="1367-2630/5/1/117">Transport theory of carbon nanotube Y junctions R Egger, B Trauzettel, S Chen and F Siano The tubular conical helix of graphitic boron nitride F F Xu, Y Bando and D Golberg Formation pathways for single-wall carbon nanotube multiterminal junctions Inna Ponomareva, Leonid A Chernozatonskii, Antonis N Andriotis and Madhu Menon Synthesis and manipulation of carbon nanotubes J W Seo, E Couteau, P Umek, K Hernadi, P Marcoux, B Lukic, Cs Mikó, M Milas, R Gaál and L Forró Transitional behaviour in the transformation from active end planes to stable loops caused by annealing M Endo, B J Lee, Y A Kim, Y J Kim, H Muramatsu, T Yanagisawa, T Hayashi, M Terrones and M S Dresselhaus Energetics and electronic structure of C70-peapods and one-dimensional chains of C70 Susumu Okada, Minoru Otani and Atsushi Oshiyama Theoretical characterization of several models of nanoporous carbon F Valencia, A H Romero, E Hernández, M Terrones and H Terrones First-principles molecular dynamics study of the stretching frequencies of hydrogen molecules in carbon nanotubes Gabriel Canto, Pablo Ordejón, Cheng Hansong, Alan C Cooper and Guido P Pez The geometry and the radial breathing mode of carbon nanotubes: beyond the ideal behaviour Jeno Kürti, Viktor Zólyomi, Miklos Kertesz and Sun Guangyu Curved nanostructured materials Humberto Terrones and Mauricio Terrones A one-dimensional Ising model for C70 molecular ordering in C70-peapods Yutaka Maniwa, Hiromichi Kataura, Kazuyuki Matsuda and Yutaka Okabe Nanoengineering of carbon nanotubes for nanotools Yoshikazu Nakayama and Seiji Akita Narrow diameter double-wall carbon nanotubes: synthesis, electron microscopy and inelastic light scattering R R Bacsa, E Flahaut, Ch Laurent, A Peigney, S Aloni, P Puech and W S Bacsa Sensitivity of sin

2003-09-01

149

Carbon nanotube-polymer composite actuators  

DOEpatents

The present invention discloses a carbon nanotube (SWNT)-polymer composite actuator and method to make such actuator. A series of uniform composites was prepared by dispersing purified single wall nanotubes with varying weight percents into a polymer matrix, followed by solution casting. The resulting nanotube-polymer composite was then successfully used to form a nanotube polymer actuator.

Gennett, Thomas (Denver, CO); Raffaelle, Ryne P. (Honeoye Falls, NY); Landi, Brian J. (Rochester, NY); Heben, Michael J. (Denver, CO)

2008-04-22

150

Synthesis and properties of magnetic molecularly imprinted polymers based on multiwalled carbon nanotubes for magnetic extraction of bisphenol A from water.  

PubMed

Novel magnetic molecularly imprinted polymers based on multiwalled carbon nanotubes (MWNTs@MMIPs) with specific selectivity toward bisphenol A were synthesized using bisphenol A as the template molecule, methacrylic acid, and ?-cyclodextrin as binary functional monomers and ethylene glycol dimethacrylate as the cross-linker. The MWNTs@MMIPs were characterized by Fourier transform infrared, vibrating sample magnetometer, and transmission electron microscopy. Batch mode adsorption experiment was carried out to investigate the specific adsorption equilibrium and kinetics of the MWNTs@MMIPs. The MWNTs@MMIPs exhibited good affinity with a maximum adsorption capacity of 49.26 ?mol g(-1) and excellent selectivity toward bisphenol A. Combined with high-performance liquid chromatography analysis, the MWNTs@MMIPs were employed to extract bisphenol A in tap water, rain water, and lake water successfully with the recoveries of 89.8-95.4, 89.9-93.4, and 87.3-94.1%, respectively. PMID:25043281

Zhang, Zhaohui; Chen, Xing; Rao, Wei; Chen, Hongjun; Cai, Rong

2014-08-15

151

Trapping cold atoms using surface-grown carbon nanotubes P. G. Petrov,1,* S. Machluf,1  

E-print Network

Trapping cold atoms using surface-grown carbon nanotubes P. G. Petrov,1,* S. Machluf,1 S. Younis,1 atomic clouds into magnetic traps created by single-wall carbon nanotubes grown directly onto dielectric surfaces. We show that atoms may be captured for experimen- tally sustainable nanotube currents, generating

Joselevich, Ernesto

152

Synthesis of carbon nanotubes and nanotube forests on copper catalyst  

NASA Astrophysics Data System (ADS)

The growth of carbon nanotubes on bulk copper is studied. We show for the first time, that super growth chemical vapor deposition method can be successfully applied for preparation of nanotubes on copper catalyst, and the presence of hydrogen is necessary. Next, different methods of copper surface activation are studied, to improve catalyst efficiency. Among them, applied for the first time for copper catalyst in nanotubes synthesis, sulfuric acid activation is the most promising. Among tested samples the surface modified for 10 min is the most active, causing the growth of vertically aligned carbon nanotube forests. Obtained results have potential importance in application of nanotubes and copper in electronic chips and nanodevices.

Kruszka, Bartosz; Terzyk, Artur P.; Wi?niewski, Marek; Gauden, Piotr A.; Szybowicz, Miros?aw

2014-09-01

153

Conductance Oscillations in Squashed Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

A combination of molecular dynamics and electrical conductance calculations are used to probe the electromechanical properties of squashed metallic carbon nanotubes. We find that the conductance and bandgap of armchair nanotubes show oscillations upon squashing. The physical origin of these oscillations is attributed to interaction of carbon atoms with a fourth neighbor. Squashing of armchair and zigzag nanotubes ultimately leads to metallic behavior.

Mehrez, H.; Anantram, M. P.; Svizhenko, A.

2003-01-01

154

Carbon Nanotube Material Quality Assessment  

NASA Technical Reports Server (NTRS)

The nanomaterial activities at NASA Johnson Space Center focus on carbon nanotube production, characterization and their applications for aerospace systems. Single wall carbon nanotubes are produced by arc and laser methods. Characterization of the nanotube material is performed using the NASA JSC protocol developed by combining analytical techniques of SEM, TEM, UV-VIS-NIR absorption, Raman, and TGA. A possible addition of other techniques such as XPS, and ICP to the existing protocol will be discussed. Changes in the quality of the material collected in different regions of the arc and laser production chambers is assessed using the original JSC protocol. The observed variations indicate different growth conditions in different regions of the production chambers.

Yowell, Leonard; Arepalli, Sivaram; Sosa, Edward; Niolaev, Pavel; Gorelik, Olga

2006-01-01

155

Roping and wrapping carbon nanotubes  

Microsoft Academic Search

Single-walled carbon nanotubes can be dispersed into solvents by ultrasonication to the point that primarily individual tubes, cut to a few hundred nanometers in length, are present. However, when such dispersions are filtered to a thick mat, or paper, only tangles of uniform, seemingly endless ropes are observed. The factors contributing to this ``roping'' phenomenon, akin to aggregation or crystallization,

Kevin D. Ausman; Michael J. O'Connell; Peter Boul; Lars M. Ericson; Michael J. Casavant; Deron A. Walters; Chad Huffman; Rajesh Saini; Yuhuang Wang; Erik Haroz; Edward W. Billups; Richard E. Smalley

2001-01-01

156

Irradiation Stability of Carbon Nanotubes  

E-print Network

Molecular Dynamics Min Minute MWNT Multi-Walled Carbon Nanotube mm Millimeter nm Nanometer pA Pico Ampere PECVD Plasma Enhanced Chemical Vapor Deposition PKA Primary Knock-On Atom PPM Parts per Million RF Radiofrequency Sec Second SDS Sodium... Variation of interatomic potential with separation distance. ........................ 30 13 The number of displaced atoms vs. PKA energy based on Kinchin-Pease model...

Aitkaliyeva, Assel

2010-01-14

157

Terahertz detection and carbon nanotubes  

ScienceCinema

Researchers at Sandia National Laboratories, along with collaborators from Rice University and the Tokyo Institute of Technology, are developing new terahertz detectors based on carbon nanotubes that could lead to significant improvements in medical imaging, airport passenger screening, food inspection and other applications.

Leonard, Francois

2014-06-13

158

Carbon Nanotubes and Human Cells?  

ERIC Educational Resources Information Center

Single-walled carbon nanotubes that were chemically altered to be water soluble are shown to enter fibroblasts, T cells, and HL60 cells. Nanoparticles adversely affect immortalized HaCaT human keratinocyte cultures, indicating that they may enter cells.

King, G. Angela

2005-01-01

159

Terahertz detection and carbon nanotubes  

SciTech Connect

Researchers at Sandia National Laboratories, along with collaborators from Rice University and the Tokyo Institute of Technology, are developing new terahertz detectors based on carbon nanotubes that could lead to significant improvements in medical imaging, airport passenger screening, food inspection and other applications.

Leonard, Francois

2014-06-11

160

Adhesion and friction of a multiwalled carbon nanotube sliding against single-walled carbon nanotube  

Microsoft Academic Search

The adhesion and friction at crossed nanotube junctions were investigated in ambient by using an atomic force microscope (AFM) in tapping mode. A multiwalled carbon nanotube (MWNT) tip attached to a conventional AFM probe was scanned across a single-walled carbon nanotube (SWNT) suspended over a 2-mum -wide trench. The interaction between nanotubes was found to critically depend on the morphology

Bharat Bhushan; Xing Ling; Alain Jungen; Christofer Hierold

2008-01-01

161

A carbon nanotube bearing and Stodola rotor  

E-print Network

A nano-scale rotor supported on a cantilevered multi-wall carbon nanotube (MWNT) shaft (Stodola configuration) is proposed. The nanotube is also expected to function as the bearing, since individual walls of a MWNT are not ...

Cook, Eugene Hightower

2008-01-01

162

Growth mechanism of single-walled carbon nanotube from catalytic reaction inside carbon nanotube template  

E-print Network

1 Growth mechanism of single-walled carbon nanotube from catalytic reaction inside carbon nanotube shiomi@photon.t.u-tokyo.ac.jp, maruyama@photon.t.u-tokyo.ac.jp RECEIVED DATE (to be automatically of a single- walled carbon nanotube (SWNT) inside a template SWNT, i.e. formation of a double-walled carbon

Maruyama, Shigeo

163

Novel magnetic SPE method based on carbon nanotubes filled with cobalt ferrite for the analysis of organochlorine pesticides in honey and tea.  

PubMed

A novel magnetic SPE method based on magnetic cobalt ferrite filled carbon nanotubes (MFCNTs) coupled with GC with electron capture detection was developed to determine organochlorine pesticides (OCPs) in tea and honey samples. The MFCNTs were prepared through the capillarity of carbon nanotubes for drawing mixed cobalt and iron nitrates solution into their inner cavity followed by heating to 550°C under Ar to form the cobalt ferrite nanoparticles. SEM images provided visible evidence of the filled cobalt ferrite nanoparticles in the multiwalled nanotubes. X-ray photoelectron spectroscopy indicated no adhesion of cobalt ferrite nanoparticles and metal salts on the outer surface of the MFCNTs. Eight OCPs were extracted with the MFCNTs. The enrichment factors were in the range of 52-68 for eight OCPs. The LODs for the eight OCPs were in the range of 1.3-3.6 ng/L. The recoveries of the OCPs for honey and tea samples were 83.2-128.7 and 72.6-111.0%, respectively. The RSDs for these samples were below 6.8%. The new method is particularly suited to extract nonpolar and weakly polar analytes from a complex matrix and could potentially be extended to other target analytes. PMID:23926126

Du, Zhuo; Liu, Miao; Li, Gongke

2013-10-01

164

SIMULATION OF CARBON NANOTUBE THz ANTENNA ARRAYS  

Microsoft Academic Search

A novel THz antenna structure, made of carbon nanotube arrays is suggested. Using CST MICROWAVE STUDIO (CST MWS), the capabilities\\u000a of carbon nanotube terahertz (THz) antenna arrays have been simulated. The dependence of gain, upon geometrical factors, e.g.,\\u000a nanotube diameter, nanotube length and the inter-tubes distance, is shown. The directivity patterns of antenna arrays and\\u000a the surface current distribution of

Ying Lan; Baoqing Zeng; Hai Zhang; Beiran Chen; Zhonghai Yang

2006-01-01

165

Magnetic solid-phase extraction based on magnetic multi-walled carbon nanotubes for the determination of phthalate monoesters in urine samples.  

PubMed

In this study, magnetic carbon nanotubes (MCNTs) were prepared by assembling magnetic nanoparticles onto the acid-treated multiwall carbon nanotubes (MWCNTs). Due to their excellent adsorption capability, the MCNTs were used as adsorbent of magnetic solid-phase extraction (MSPE) to extract phthalate monoesters (PMEs), the main biomarkers of phthalate exposure, from human urine. By coupling MSPE with gas chromatography-mass spectrometry (GC-MS), a reliable, sensitive and cost-effective method for the simultaneous determination of five main PMEs including monomethyl phthalate (MMP), monoethyl phthalate (MEP), mono n-butyl phthalate (MBP), mono-(2-ethylhexyl) phthalate (MEHP) and monobenzyl phthalate (MBzP) was developed. The factors that could influence the extraction, including the amount of magnetic nanoparticles, pH of sample solution, extraction and desorption time, the amount of salt addition, the type and volume of desorption solvent were investigated in detail. Under optimized conditions, the LODs and LOQs achieved were in the range of 0.025-0.050 and 0.125-0.250 ng mL(-1) respectively. And calibration curves were linear (r(2)?0.992) over the concentration ranges from 0.250 to 250 ng mL(-1). In addition, a satisfying reproducibility was achieved by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) less than 11.2% and 11.4%, respectively. The recoveries of the five PMEs ranged from 92.6% to 98.8% with the RSDs less than 10.7%. Finally, the established MSPE-GC-MS method was successfully applied to determine PMEs in human urine samples. MMP, MEP, MBP and MEHP were detected in most of the samples with the median concentration of 8.46, 9.26, 13.60, and 5.95 ng mL(-1) respectively. MBzP was detected in 58.3% of the samples with the median concentration of 3.05 ng mL(-1). Taken together, the MSPE-GC-MS method developed in current study provides a new option for the determination of PMEs in human urine. PMID:23510960

Rastkari, Noushin; Ahmadkhaniha, Reza

2013-04-19

166

Optical conductivity of carbon nanotubes  

NASA Astrophysics Data System (ADS)

The effect of electron-phonon interaction on the optical conductivity of semiconducting carbon nanotubes is studied. In this manner, the Kubo-Greenwood formula, Green's function technique and the Holstein Hamiltonian model are used. The optical conductivity of the system shows different behaviors between low and high frequency region. In the low frequency, the optical conductivity increases with electron-phonon coupling strength increasing while it has no noticeable change in the high frequency region. The results also show that the optical conductivity increases with increasing of nanotube's diameter.

Mousavi, Hamze

2012-06-01

167

Carbon-Nanotube Schottky Diodes  

NASA Technical Reports Server (NTRS)

Schottky diodes based on semiconducting single-walled carbon nanotubes are being developed as essential components of the next generation of submillimeter-wave sensors and sources. Initial performance predictions have shown that the performance characteristics of these devices can exceed those of the state-of-the-art solid-state Schottky diodes that have been the components of choice for room-temperature submillimeter-wave sensors for more than 50 years. For state-of-the-art Schottky diodes used as detectors at frequencies above a few hundred gigahertz, the inherent parasitic capacitances associated with their semiconductor junction areas and the resistances associated with low electron mobilities limit achievable sensitivity. The performance of such a detector falls off approximately exponentially with frequency above 500 GHz. Moreover, when used as frequency multipliers for generating signals, state-of-the-art solid-state Schottky diodes exhibit extremely low efficiencies, generally putting out only micro-watts of power at frequencies up to 1.5 THz. The shortcomings of the state-of-the-art solid-state Schottky diodes can be overcome by exploiting the unique electronic properties of semiconducting carbon nanotubes. A single-walled carbon nanotube can be metallic or semiconducting, depending on its chirality, and exhibits high electron mobility (recently reported to be approx.= 2x10(exp 5)sq cm/V-s) and low parasitic capacitance. Because of the narrowness of nanotubes, Schottky diodes based on carbon nanotubes have ultra-small junction areas (of the order of a few square nanometers) and consequent junction capacitances of the order of 10(exp -18) F, which translates to cutoff frequency >5 THz. Because the turn-on power levels of these devices are very low (of the order of nano-watts), the input power levels needed for pumping local oscillators containing these devices should be lower than those needed for local oscillators containing state-of-the-art solid-state Schottky diodes.

Manohara, Harish; Wong, Eric; Schlecht, Erich; Hunt, Brian; Siegel, Peter

2006-01-01

168

Nanoscale Fluorescence Microscopy Using Carbon Nanotubes  

Microsoft Academic Search

We demonstrate the first reported use of single-walled carbon nanotubes as nano-optical probes in apertureless near-field fluorescence microscopy. We show that, in contrast to silicon probes, carbon nanotubes always cause strong fluorescence quenching when used to image dye-doped polystyrene spheres and Cd-Se quantum dots. For quantum dots, the carbon nanotubes induce very strong near-field contrast with a spatial resolution of

Chun Mu; Benjamin D. Mangum; Changan Xie; Jordan M. Gerton

2008-01-01

169

Method of making carbon nanotube composite materials  

DOEpatents

The present invention is a method of making a composite polymeric material by dissolving a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes and optionally additives in a solvent to make a solution and removing at least a portion of the solvent after casting onto a substrate to make thin films. The material has enhanced conductivity properties due to the blending of the un-functionalized and hydroxylated carbon nanotubes.

O'Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas

2014-05-20

170

Carbon Nanotube Terahertz Polarizer Cary L. Pint,,,|  

E-print Network

Carbon Nanotube Terahertz Polarizer Lei Ren,, Cary L. Pint,,§,| Layla G. Booshehri,, William D, 2009 ABSTRACT We describe a film of highly aligned single-walled carbon nanotubes that acts perfect alignment as well as intrinsically anisotropic terahertz response of single-walled carbon

Kono, Junichiro

171

Carbon nanotubes: nanomechanics, manipulation, and electronic devices  

Microsoft Academic Search

Carbon nanotubes are novel materials with unique electrical and mechanical properties. Here we present results on their atomic structure and mechanical properties in the adsorbed state, on ways to manipulate individual nanotubes, on their electrical properties and, finally, on the fabrication and characteristics of nanotube-based electron devices. Specifically, atomic force microscopy (AFM) and molecular mechanics simulations are used to investigate

P. Avouris; T Hertel; R Martel; T Schmidt; H. R Shea; R. E Walkup

1999-01-01

172

Raman spectroscopy of metallic carbon nanotubes  

E-print Network

Metallic carbon nanotubes are one dimensional conductors that are both technologically promising for electronic applications, and scientifically interesting for studying the physics of low dimensional materials. In this ...

Farhat, Hootan

2010-01-01

173

Carbon Nanotubes: Molecular Electronic Components  

NASA Technical Reports Server (NTRS)

The carbon Nanotube junctions have recently emerged as excellent candidates for use as the building blocks in the formation of nanoscale molecular electronic networks. While the simple joint of two dissimilar tubes can be generated by the introduction of a pair of heptagon-pentagon defects in an otherwise perfect hexagonal graphene sheet, more complex joints require other mechanisms. In this work we explore structural characteristics of complex 3-point junctions of carbon nanotubes using a generalized tight-binding molecular-dynamics scheme. The study of pi-electron local densities of states (LDOS) of these junctions reveal many interesting features, most prominent among them being the defect-induced states in the gap.

Srivastava, Deepak; Saini, Subhash; Menon, Madhu

1997-01-01

174

Polyethylene multiwalled carbon nanotube composites  

Microsoft Academic Search

Polyethylene (PE) multiwalled carbon nanotubes (MWCNTs) with weight fractions ranging from 0.1 to 10wt% were prepared by melt blending using a mini-twin screw extruder. The morphology and degree of dispersion of the MWCNTs in the PE matrix at different length scales was investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and wide-angle X-ray diffraction

Tony McNally; Petra Pötschke; Peter Halley; Michael Murphy; Darren Martin; Steven E. J. Bell; Gerard P. Brennan; Daniel Bein; Patrick Lemoine; John Paul Quinn

2005-01-01

175

Carbon nanotubes in tissue engineering.  

PubMed

As a result of their peculiar features, carbon nanotubes (CNTs) are emerging in many areas of nanotechnology applications. CNT-based technology has been increasingly proposed for biomedical applications, to develop biomolecule nanocarriers, bionanosensors and smart material for tissue engineering purposes. In the following chapter this latter application will be explored, describing why CNTs can be considered an ideal material able to support and boost the growth and the proliferation of many kinds of tissues. PMID:24072586

Bosi, Susanna; Ballerini, Laura; Prato, Maurizio

2014-01-01

176

Carbon nanotube initiated formation of carbon nanoscrolls Zhao Zhang1  

E-print Network

Carbon nanotube initiated formation of carbon nanoscrolls Zhao Zhang1 and Teng Li1,2,a 1 Department; published online 26 August 2010 The unique topology and exceptional properties of carbon nanoscrolls CNSs graphene on a substrate, initiated by a carbon nanotube CNT . The rolling of graphene into a CNS

Li, Teng

177

Engineering carbon nanotubes and nanotube circuits using electrical breakdown.  

PubMed

Carbon nanotubes display either metallic or semiconducting properties. Both large, multiwalled nanotubes (MWNTs), with many concentric carbon shells, and bundles or "ropes" of aligned single-walled nanotubes (SWNTs), are complex composite conductors that incorporate many weakly coupled nanotubes that each have a different electronic structure. Here we demonstrate a simple and reliable method for selectively removing single carbon shells from MWNTs and SWNT ropes to tailor the properties of these composite nanotubes. We can remove shells of MWNTs stepwise and individually characterize the different shells. By choosing among the shells, we can convert a MWNT into either a metallic or a semiconducting conductor, as well as directly address the issue of multiple-shell transport. With SWNT ropes, similar selectivity allows us to generate entire arrays of nanoscale field-effect transistors based solely on the fraction of semiconducting SWNTs. PMID:11326094

Collins, P G; Arnold, M S; Avouris, P

2001-04-27

178

Improved Process for Fabricating Carbon Nanotube Probes  

NASA Technical Reports Server (NTRS)

An improved process has been developed for the efficient fabrication of carbon nanotube probes for use in atomic-force microscopes (AFMs) and nanomanipulators. Relative to prior nanotube tip production processes, this process offers advantages in alignment of the nanotube on the cantilever and stability of the nanotube's attachment. A procedure has also been developed at Ames that effectively sharpens the multiwalled nanotube, which improves the resolution of the multiwalled nanotube probes and, combined with the greater stability of multiwalled nanotube probes, increases the effective resolution of these probes, making them comparable in resolution to single-walled carbon nanotube probes. The robust attachment derived from this improved fabrication method and the natural strength and resiliency of the nanotube itself produces an AFM probe with an extremely long imaging lifetime. In a longevity test, a nanotube tip imaged a silicon nitride surface for 15 hours without measurable loss of resolution. In contrast, the resolution of conventional silicon probes noticeably begins to degrade within minutes. These carbon nanotube probes have many possible applications in the semiconductor industry, particularly as devices are approaching the nanometer scale and new atomic layer deposition techniques necessitate a higher resolution characterization technique. Previously at Ames, the use of nanotube probes has been demonstrated for imaging photoresist patterns with high aspect ratio. In addition, these tips have been used to analyze Mars simulant dust grains, extremophile protein crystals, and DNA structure.

Stevens, R.; Nguyen, C.; Cassell, A.; Delzeit, L.; Meyyappan, M.; Han, Jie

2003-01-01

179

Plasticity and Kinky Chemistry of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

Since their discovery in 1991, carbon nanotubes have been the subject of intense research interest based on early predictions of their unique mechanical, electronic, and chemical properties. Materials with the predicted unique properties of carbon nanotubes are of great interest for use in future generations of aerospace vehicles. For their structural properties, carbon nanotubes could be used as reinforcing fibers in ultralight multifunctional composites. For their electronic properties, carbon nanotubes offer the potential of very high-speed, low-power computing elements, high-density data storage, and unique sensors. In a continuing effort to model and predict the properties of carbon nanotubes, Ames accomplished three significant results during FY99. First, accurate values of the nanomechanics and plasticity of carbon nanotubes based on quantum molecular dynamics simulations were computed. Second, the concept of mechanical deformation catalyzed-kinky-chemistry as a means to control local chemistry of nanotubes was discovered. Third, the ease of nano-indentation of silicon surfaces with carbon nanotubes was established. The elastic response and plastic failure mechanisms of single-wall nanotubes were investigated by means of quantum molecular dynamics simulations.

Srivastava, Deepak; Dzegilenko, Fedor

2000-01-01

180

Understanding the Metal-Carbon Interface in FePt Catalyzed Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Any tip functionalization of carbon nanotubes, for which the relative orientation between their (metallic) catalyst particle and the nanotube axis is essential, requires a detailed knowledge of the nature of the internal interface between the particle and the outgrown tube. In the present work, this interface is characterized with atomic precision using state-of-the-art low-voltage aberration-corrected transmission electron microscopy in combination with molecular dynamics simulations for the case of hard-magnetically terminated carbon nanotubes. Our results indicate that the physical principle based upon which the interfacial metal facet is chosen is a reduction of the desorption energy for carbon.

Pohl, D.; Schäffel, F.; Rümmeli, M. H.; Mohn, E.; Täschner, C.; Schultz, L.; Kisielowski, C.; Rellinghaus, B.

2011-10-01

181

Controlled synthesis of single-walled carbon nanotubes.  

E-print Network

??The chemistry and applications of carbon nanotubes are critically dependent on nanotube chirality. To date, no one has demonstrated chirality-selective synthesis of single-walled carbon nanotubes… (more)

McJilton, Laura Anne

2009-01-01

182

Catalytic Routes Towards Single Wall Carbon Nanotubes  

Microsoft Academic Search

Single wall carbon nanotubes (SWCNT) have become a strategic material in the area of nanotechnologies nowadays, and catalytic chemical vapor deposition seems to be the most promising technique in view of an industrial?scale production. However, the selective catalytic production of single wall carbon nanotubes is still a challenge, since catalytic systems performances both in terms of selectivity and activity are

Emmanuel Lamouroux; Philippe Serp; Philippe Kalck

2007-01-01

183

Electrospinning carbon nanotube polymer composite nanofibers  

Microsoft Academic Search

The unique and exceptional physical properties of carbon nanotubes have inspired their use as a filler within a polymeric matrix to produce carbon nanotube polymer composites with enhanced mechanical, thermal and electrical properties. A powerful method of synthesising nanofibers comprising these polymer composites is electrospinning, which utilises an applied electric stress to draw out a thin nanometer-dimension fiber from the

Leslie Y. Yeo; James R. Friend

2006-01-01

184

Unzipping carbon nanotubes at high impact.  

PubMed

The way nanostructures behave and mechanically respond to high impact collision is a topic of intrigue. For anisotropic nanostructures, such as carbon nanotubes, this response will be complicated based on the impact geometry. Here we report the result of hypervelocity impact of nanotubes against solid targets and show that impact produces a large number of defects in the nanotubes, as well as rapid atom evaporation, leading to their unzipping along the nanotube axis. Fully atomistic reactive molecular dynamics simulations are used to gain further insights of the pathways and deformation and fracture mechanisms of nanotubes under high energy mechanical impact. Carbon nanotubes have been unzipped into graphene nanoribbons before using chemical treatments but here the instability of nanotubes against defect formation, fracture, and unzipping is revealed purely through mechanical impact. PMID:24915176

Ozden, Sehmus; Autreto, Pedro A S; Tiwary, Chandra Sekhar; Khatiwada, Suman; Machado, Leonardo; Galvao, Douglas S; Vajtai, Robert; Barrera, Enrique V; Ajayan, Pulickel M

2014-07-01

185

Orthogonal orientation control of carbon nanotube growth.  

PubMed

Carbon nanotubes (CNTs) have attracted attention for their remarkable electrical properties and have being explored as one of the best building blocks in nano-electronics. A key challenge to realize such potential is the control of the nanotube growth directions. Even though both vertical growth and controlled horizontal growth of carbon nanotubes have been realized before, the growth of complex nanotube structures with both vertical and horizontal orientation control on the same substrate has never been achieved. Here, we report a method to grow three-dimensional (3D) complex nanotube structures made of vertical nanotube forests and horizontal nanotube arrays on a single substrate and from the same catalyst pattern by an orthogonally directed nanotube growth method using chemical vapor deposition (CVD). More importantly, such a capability represents a major advance in controlled growth of carbon nanotubes. It enables researchers to control the growth directions of nanotubes by simply changing the reaction conditions. The high degree of control represented in these experiments will surely make the fabrication of complex nanotube devices a possibility. PMID:20000705

Zhou, Weiwei; Ding, Lei; Yang, Sungwoo; Liu, Jie

2010-01-13

186

Induced and intrinsic superconductivity in carbon nanotubes  

NASA Astrophysics Data System (ADS)

Metallic single wall carbon nanotubes have attracted considerable interest as 1D quantum wires combining a low carrier density and a high mobility. It was believed for a long time that low temperature transport was exclusively dominated by the existence of unscreened Coulomb interactions leading to insulating behaviour at low temperature. However, experiments have also shown evidence of superconductivity in carbon nanotubes. We distinguish two fundamentally different physical situations. When carbon nanotubes are connected to superconducting electrodes, they exhibit proximity-induced superconductivity strongly dependent on the transmission of the electrodes. On the other hand, intrinsic superconductivity was also observed in suspended ropes of carbon nanotubes, in doped or very small diameter individual tubes. These experiments indicate the presence of attractive interactions in carbon nanotubes which overcome Coulomb repulsion at low temperature and enable investigation of superconductivity in a 1D limit never explored before.

Ferrier, M.; Kasumov, A.; Deblock, R.; Guéron, S.; Bouchiat, H.

2010-09-01

187

Mechanics of carbon nanotube scission under sonication  

NASA Astrophysics Data System (ADS)

As-produced carbon nanotubes come in bundles that must be exfoliated for practical applications in nanocomposites. Sonication not only causes the exfoliation of nanotube bundles but also unwanted scission. An understanding of how precisely sonication induces the scission and exfoliation of nanotubes will help maximising the degree of exfoliation while minimising scission. We present a theoretical study of the mechanics of carbon nanotube scission under sonicaton, based on the accepted view that it is caused by strong gradients in the fluid velocity near a transiently collapsing bubble. We calculate the length-dependent scission rate by taking the actual movement of the nanotube during the collapse of a bubble into account, allowing for the prediction of the temporal evolution of the length distribution of the nanotubes. We show that the dependence of the scission rate on the sonication settings and the nanotube properties results in non-universal, experiment-dependent scission kinetics potentially explaining the variety in experimentally observed scission kinetics. The non-universality arises from the dependence of the maximum strain rate of the fluid experienced by a nanotube on its length. The maximum strain rate that a nanotube experiences increases with decreasing distance to the bubble. As short nanotubes are dragged along more easily by the fluid flow they experience a higher maximum strain rate than longer nanotubes. This dependence of the maximum strain rate on nanotube length affects the scaling of tensile strength with terminal length. We find that the terminal length scales with tensile strength to the power of 1/1.16 instead of with an exponent of 1/2 as found when nanotube motion is neglected. Finally, we show that the mechanism we propose responsible for scission can also explain the exfoliation of carbon nanotube bundles.

Stegen, J.

2014-06-01

188

Mechanics of carbon nanotube scission under sonication.  

PubMed

As-produced carbon nanotubes come in bundles that must be exfoliated for practical applications in nanocomposites. Sonication not only causes the exfoliation of nanotube bundles but also unwanted scission. An understanding of how precisely sonication induces the scission and exfoliation of nanotubes will help maximising the degree of exfoliation while minimising scission. We present a theoretical study of the mechanics of carbon nanotube scission under sonicaton, based on the accepted view that it is caused by strong gradients in the fluid velocity near a transiently collapsing bubble. We calculate the length-dependent scission rate by taking the actual movement of the nanotube during the collapse of a bubble into account, allowing for the prediction of the temporal evolution of the length distribution of the nanotubes. We show that the dependence of the scission rate on the sonication settings and the nanotube properties results in non-universal, experiment-dependent scission kinetics potentially explaining the variety in experimentally observed scission kinetics. The non-universality arises from the dependence of the maximum strain rate of the fluid experienced by a nanotube on its length. The maximum strain rate that a nanotube experiences increases with decreasing distance to the bubble. As short nanotubes are dragged along more easily by the fluid flow they experience a higher maximum strain rate than longer nanotubes. This dependence of the maximum strain rate on nanotube length affects the scaling of tensile strength with terminal length. We find that the terminal length scales with tensile strength to the power of 1/1.16 instead of with an exponent of 1/2 as found when nanotube motion is neglected. Finally, we show that the mechanism we propose responsible for scission can also explain the exfoliation of carbon nanotube bundles. PMID:24985679

Stegen, J

2014-06-28

189

Hydrogenation of single-walled carbon nanotubes  

E-print Network

Towards the development of a useful mechanism for hydrogen storage, we have studied the hydrogenation of single-walled carbon nanotubes with atomic hydrogen using core-level photoelectron spectroscopy and x-ray absorption spectroscopy. We find that atomic hydrogen creates C-H bonds with the carbon atoms in the nanotube walls and such C-H bonds can be com-pletely broken by heating to 600 oC. We demonstrate approximately 65+/-15 at % hydrogenation of carbon atoms in the single-walled carbon nanotubes which is equivalent to 5.1+/-1.2 weight % hydrogen capacity. We also show that the hydrogenation is a reversible process.

Anton Nikitin; Hirohito Ogasawara; David Mann; Reinhard Denecke; Zhiyong Zhang; Hongjie Dai; KJ Cho; Anders Nilsson

2005-10-14

190

Coated carbon nanotube array electrodes  

DOEpatents

The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

Ren, Zhifeng (Newton, MA); Wen, Jian (Newton, MA); Chen, Jinghua (Chestnut Hill, MA); Huang, Zhongping (Belmont, MA); Wang, Dezhi (Wellesley, MA)

2008-10-28

191

Carbon nanotube growth density control  

NASA Technical Reports Server (NTRS)

Method and system for combined coarse scale control and fine scale control of growth density of a carbon nanotube (CNT) array on a substrate, using a selected electrical field adjacent to a substrate surface for coarse scale density control (by one or more orders of magnitude) and a selected CNT growth temperature range for fine scale density control (by multiplicative factors of less than an order of magnitude) of CNT growth density. Two spaced apart regions on a substrate may have different CNT growth densities and/or may use different feed gases for CNT growth.

Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

2010-01-01

192

Peptides with selective affinity for carbon nanotubes.  

PubMed

Because of their extraordinary electronic and mechanical properties, carbon nanotubes have great potential as materials for applications ranging from molecular electronics to ultrasensitive biosensors. Biological molecules interacting with carbon nanotubes provide them with specific chemical handles that would make several of these applications possible. Here we use phage display to identify peptides with selective affinity for carbon nanotubes. Binding specificity has been confirmed by demonstrating direct attachment of nanotubes to phage and free peptides immobilized on microspheres. Consensus binding sequences show a motif rich in histidine and tryptophan, at specific locations. Our analysis of peptide conformations shows that the binding sequence is flexible and folds into a structure matching the geometry of carbon nanotubes. The hydrophobic structure of the peptide chains suggests that they act as symmetric detergents. PMID:12612679

Wang, Siqun; Humphreys, Elen S; Chung, Sung-Yoon; Delduco, Daniel F; Lustig, Steven R; Wang, Hong; Parker, Kimberley N; Rizzo, Nancy W; Subramoney, Shekhar; Chiang, Yet-Ming; Jagota, Anand

2003-03-01

193

Electron emission properties of carbon nanotubes  

NASA Astrophysics Data System (ADS)

We report on the field emission properties of carbon nanotubes, focusing on current density versus electric field ( J- F) characteristics and the spacing between the emitter and collector. We grew carbon nanotubes on SUS304, nickel, Inconel-600, and Invar-42 substrates using plasma-enhanced chemical vapor deposition, using methane gas as the carbon source and hydrogen gas as the catalyst and dilution gas. We found that nanotubes grew fastest on Invar-42. Nanotubes were distributed from 50 to 100 nm in diameter and from 1 to 30 ?m long. Onset field of the field emission was 0.7 V/?m and the current density was 1 mA/cm 2 at an electric field of 3.0 V/?m. A Fowler-Nordheim plot was made. Field enhancement factor ? and emission area ? were calculated and compared between substrates. Using nickel on quartz glass, carbon nanotubes were selectively fabricated on metal lines on quartz glass.

Hirakawa, Masaaki; Sonoda, Saki; Tanaka, Chiaki; Murakami, Hirohiko; Yamakawa, Hiroyuki

2001-01-01

194

Review of carbon nanotube nanoelectronics and macroelectronics  

NASA Astrophysics Data System (ADS)

Carbon nanotubes have the potential to spur future development in electronics due to their unequalled electrical properties. In this article, we present a review on carbon nanotube-based circuits in terms of their electrical performance in two major directions: nanoelectronics and macroelectronics. In the nanoelectronics direction, we direct our discussion to the performance of aligned carbon nanotubes for digital circuits and circuits designed for radio-frequency applications. In the macroelectronics direction, we focus our attention on the performance of thin films of carbon nanotube random networks in digital circuits, display applications, and printed electronics. In the last part, we discuss the existing challenges and future directions of nanotube-based nano- and microelectronics.

Che, Yuchi; Chen, Haitian; Gui, Hui; Liu, Jia; Liu, Bilu; Zhou, Chongwu

2014-07-01

195

Scanned Probe Microscopy of Electronic Transport in Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

We use electrostatic force microscopy and scanned gate microscopy to probe the conducting properties of carbon nanotubes at room temperature. Multiwalled carbon nanotubes are shown to be diffusive conductors, while metallic single-walled carbon nanotubes are ballistic conductors over micron lengths. Semiconducting single-walled carbon nanotubes are shown to have a series of large barriers to conduction along their length. These measurements are also used to probe the contact resistance and locate breaks in carbon nanotube circuits.

Bachtold, A.; Fuhrer, M. S.; Plyasunov, S.; Forero, M.; Anderson, Erik H.; Zettl, A.; McEuen, Paul L.

2000-06-01

196

Dispersions, novel nanomaterial sensors and nanoconjugates based on carbon nanotubes.  

PubMed

Nanomaterials are structures with dimensions characteristically much below 100 nm. The unique physical properties (e.g., conductivity, reactivity) have placed these nanomaterials in the forefront of emerging technologies. Significant enhancement of optical, mechanical, electrical, structural, and magnetic properties are commonly found through the use of novel nanomaterials. One of the most exciting classes of nanomaterials is represented by the carbon nanotubes. Carbon nanotubes, including single-wall carbon nanotubes, multi-wall carbon nanotubes, and concentric tubes have been shown to possess superior electronic, thermal, and mechanical properties to be attractive for a wide range of potential applications They sometimes bunch to form "ropes" and show great potential for use as highly sensitive electronic (bio)sensors due to the very small diameter, directly comparable to the size of single analyte molecules and that every single carbon atom is in direct contact with the environment, allowing optimal interaction with nearby molecules. Composite materials based on integration of carbon nanotubes and some other materials to possess properties of the individual components with a synergistic effect have gained growing interest. Materials for such purposes include conducting polymers, redox mediators and metal nanoparticles. These tubes provide the necessary building blocks for electronic circuits and afford new opportunities for chip miniaturization, which can dramatically improve the scaling prospects for the semiconductor technologies and the fabrication of devices, including field-effect transistors and sensors. Carbon nanotubes are one of the ideal materials for the preparation of nanoelectronic devices and nanosensors due to the unique electrical properties, outstanding electrocatalytic properties, high chemical stability and larger specific surface area of nanotubes. Carbon nanotubes are attractive material for supercapacitors due to their unique one-dimensional mesoporous structure, high specific surface area, low resistivity and good chemical stability. Nanoscaled composite materials based on carbon nanotubes have been broadly used due to their high chemical inertness, non-swelling effect, high purity and rigidity. The integration of carbon nanotubes with organics, biomaterials and metal nanoparticles has led to the development of new hybrid materials and sensors. Hybrid nanoscale materials are well established in various processes such as organic and inorganic compounds, nucleic acid detachment, protein separation, and immobilization of enzymes. Those nanostructures can be used as the building blocks for electronics and nanodevices because uniform organic and metal coatings with the small and monodisperse domain sizes are crucial to optimize nanoparticle conductivity and to detect changes in conductivity and absorption induced by analyte adsorption on these surfaces. The highly ordered assembly of zero-dimensional and one-dimensional nanoparticles is not only necessary for making functional devices, but also presents an opportunity to develop novel collective properties. PMID:19573856

Capek, Ignác

2009-09-30

197

Conceptual design of carbon nanotube processes  

Microsoft Academic Search

Carbon nanotubes, discovered in 1991, are a new form of pure carbon that is perfectly straight tubules with diameter in nanometers,\\u000a length in microns. The conceptual designs of two processes are described for the industrial-scale production of carbon nanotubes\\u000a that are based on available laboratory synthesis techniques and purification methods. Two laboratory-scale catalytic chemical\\u000a vapor deposition reactors were selected for

Adedeji E. Agboola; Ralph W. Pike; T. A. Hertwig; Helen H. Lou

2007-01-01

198

Buckling of defective carbon nanotubes  

NASA Astrophysics Data System (ADS)

Presented herein is an investigation into the buckling behavior of single-walled carbon nanotubes (SWCNTs) with defects via molecular dynamics (MD) simulations. Various kinds of defects including point defects (monovacancy, bivacancies, and line) and topological defect such as Stone-Wales (SW) are considered. The MD simulations performed on the SWCNTs are based on the reactive empirical bond-order and Lennard-Jones potentials for the bonded and nonbonded interactions, respectively. Different temperatures were considered to explore the thermal effect on the buckling behaviors of defective SWCNTs. It is observed that initial defects in the SWCNTs reduce their buckling capacities. The degree of reduction depends on the type of defects, chirality, and temperature. Point defects cause a greater reduction in buckling loads than SW defect. The degradation of the buckling resistance of carbon nanotubes is greater for zigzag CNTs at lower temperatures. It is also observed that reconstruction of defective SWCNTs can be realized either in a higher thermal environment or with a larger compressive force.

Zhang, Y. Y.; Xiang, Y.; Wang, C. M.

2009-12-01

199

A novel magnetic ionic liquid modified carbon nanotube for the simultaneous determination of aryloxyphenoxy-propionate herbicides and their metabolites in water.  

PubMed

A reliable, sensitive, rapid and environmentally friendly analysis procedure for the simultaneous determination of the analytes with a wide range of polarity in the environmental water was developed by coupling dispersive magnetic solid-phase extraction (d-MSPE) with high-performance liquid chromatography (HPLC)-diode array detector (DAD) and ultra-high pressure liquid chromatography (UHPLC)-triple quadrupole mass spectrometer (MS/MS), in this work. Magnetic ionic liquid modified multi-walled carbon nanotubes (m-IL-MWCNTs) were prepared by spontaneous assembly of magnetic nanoparticles and imidazolium-modified carbon nanotubes, and used as the sorbent of d-MSPE to simultaneously extract aryloxyphenoxy-propionate herbicides (AOPPs) and their polar acid metabolites due to the excellent ?-? electron donor-acceptor interactions and anion exchange ability. The factors, including the amount of sorbent, pH of the sample solution, extraction time and the volume of elution solvent were investigated. Under the optimized conditions, the proposed d-MSPE coupling to HPLC-DAD system had a satisfactory performance, the limits of detection (LODs, defined as the signal to noise ratio of 3) and the limits of quantification (LOQs, defined as the signal to noise ratio of 10) for analytes in Milli-Q water were in the range of 2.8-14.3 and 9.8-43.2?gL(-1) respectively. Calibration curves were linear (r(2)>0.998) over the concentration range from 0.02 to 1mgL(-1). The recoveries of the eight analytes ranged from 66.1 to 89.6% with the RSDs less than 8.6%. In order to extend the method in extremely low concentration analysis, d-MSPE-UHPLC-MS/MS was investigated, which showed better performance in terms of limit of detection and analysis time. PMID:25441884

Luo, Mai; Liu, Donghui; Zhao, Lu; Han, Jiajun; Liang, Yiran; Wang, Peng; Zhou, Zhiqiang

2014-12-10

200

Pyrolytic carbon nanotubes from vapor-grown carbon fibers  

Microsoft Academic Search

The structure of as-grown and heat-treated pyrolytic carbon nanotubes (PCNTs) produced by hydrocarbon pyrolysis are discussed on the basis of a possible growth process. The structures are compared with those of nanotubes obtained by the arc method (ACNT; arc-formed carbon nanotubes). PCNTs, with and without secondary pyrolytic deposition (which results in diameter increase) are found to form during pyrolysis of

Morinobu Endo; Kenji Takeuchi; Kiyoharu Kobori; Katsushi Takahashi; Harold W. Kroto; A. Sarkar

1995-01-01

201

Carbon Nanotube GHz Nano-Resonator Shengdong Li1  

E-print Network

Carbon Nanotube GHz Nano-Resonator Shengdong Li1 , Zhen Yu1 , Sheng-Feng Yen1 , Peter J. Burke1 walled carbon nanotube. Both semiconducting and metallic nanotubes are measured. Using a semiconducting signal processing components based on carbon nanotubes. Index Terms -- Nanotechnology, Resonators, Tuning

Tang, William C

202

Manipulation and Imaging of Individual Single-Walled Carbon Nanotubes  

E-print Network

Manipulation and Imaging of Individual Single-Walled Carbon Nanotubes with an Atomic Force of individual single-walled carbon nanotubes and nanotube junctions by AFM. We present ma- nipulation experiments on individual single-walled carbon nanotubes, where the tip of an AFM is used to change

203

Methods for producing reinforced carbon nanotubes  

DOEpatents

Methods for producing reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials are disclosed. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

Ren, Zhifen (Newton, MA); Wen, Jian Guo (Newton, MA); Lao, Jing Y. (Chestnut Hill, MA); Li, Wenzhi (Brookline, MA)

2008-10-28

204

Carbon nanotube fiber spun from wetted ribbon  

SciTech Connect

A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

2014-04-29

205

Lithographically Cut Single-Walled Carbon Nanotubes: Controlling Length  

E-print Network

Lithographically Cut Single-Walled Carbon Nanotubes: Controlling Length Distribution ambient conditions. Although single-walled carbon nanotubes (SWNTs) exhibit many favorable electronic 19880 Received April 11, 2003; Revised Manuscript Received June 9, 2003 ABSTRACT Single-walled carbon

Rollins, Andrew M.

206

Carbon nanotube synthesis for integrated circuit interconnects  

E-print Network

Based on their properties, carbon nanotubes (CNTs) have been identified as ideal replacements for copper interconnects in integrated circuits given their higher current density, inertness, and higher resistance to ...

Nessim, Gilbert Daniel

2009-01-01

207

Transplanting assembly of individual carbon nanotubes  

E-print Network

Handling and assembling individual nanostructures to bigger scale systems such as MEMS have been the biggest challenge. A deterministic assembly of individual carbon nanotubes by transplanting them to MEMS structures is ...

Kim, Soohyung

2009-01-01

208

Carbon nanotube bearings in theory and practice  

E-print Network

Carbon Nanotubes (CNTs) are attractive elements for bearings in Micro-Electro-Mechanical Systems (MEMS), because their structure comprises nested shells with no bonding and sub-nanometer spacing between them, enabling ...

Cook, Eugene Hightower

2011-01-01

209

Continuous Growth of Vertically Aligned Carbon Nanotubes  

E-print Network

Vertically aligned carbon nanotubes (VACNTs), sometimes called forests or carpets, are a promising material due to their unique physical and scale-dependent physical properties [1-3]. Continuous production of VACNTs is ...

Guzman de Villoria, R.

210

Carbon nanotube polymer composition and devices  

DOEpatents

A thin film device and compound having an anode, a cathode, and at least one light emitting layer between the anode and cathode, the at least one light emitting layer having at least one carbon nanotube and a conductive polymer.

Liu, Gao (Oakland, CA); Johnson, Stephen (Richmond, CA); Kerr, John B. (Oakland, CA); Minor, Andrew M. (El Cerrito, CA); Mao, Samuel S. (Castro Valley, CA)

2011-06-14

211

Double-walled carbon nanotube solar cells.  

PubMed

We directly configured double-walled carbon nanotubes as energy conversion materials to fabricate thin-film solar cells, with nanotubes serving as both photogeneration sites and a charge carriers collecting/transport layer. The solar cells consist of a semitransparent thin film of nanotubes conformally coated on a n-type crystalline silicon substrate to create high-density p-n heterojunctions between nanotubes and n-Si to favor charge separation and extract electrons (through n-Si) and holes (through nanotubes). Initial tests have shown a power conversion efficiency of >1%, proving that DWNTs-on-Si is a potentially suitable configuration for making solar cells. Our devices are distinct from previously reported organic solar cells based on blends of polymers and nanomaterials, where conjugate polymers generate excitons and nanotubes only serve as a transport path. PMID:17608444

Wei, Jinquan; Jia, Yi; Shu, Qinke; Gu, Zhiyi; Wang, Kunlin; Zhuang, Daming; Zhang, Gong; Wang, Zhicheng; Luo, Jianbin; Cao, Anyuan; Wu, Dehai

2007-08-01

212

Magnetic nanocomposite of anti-human IgG/COOH-multiwalled carbon nanotubes/Fe?O? as a platform for electrochemical immunoassay.  

PubMed

An electrochemical immunosensing method was developed based on a magnetic nanocomposite. The multiwalled carbon nanotubes (MWCNTs) were treated with nitric acid to produce carboxyl groups at the open ends. Then, Fe?O? nanoparticles were deposited on COOH-MWCNTs by chemical coprecipitation of Fe²? and Fe³? salts in an alkaline solution. Goat anti-human IgG (anti-hIgG) was covalently attached to magnetic nanocomposite through amide bond formation between the carboxylic groups of MWCNTs and the amine groups of anti-hIgG. The prepared bio-nanocomposite was used for electrochemical sensing of human tetanus IgG (hIgG) as a model antigen. The anti-hIgG magnetic nanocomposite was fixed on the surface of a gold plate electrode using a permanent magnet. The hIgG was detected using horseradish peroxidase (HRP)-conjugated anti-hIgG in a sandwich model. Electrochemical detection of hIgG was carried out in the presence of H?O? and KI as substrates of HRP. Using this method, hIgG was detected in a concentration range from 30 to 1000 ng ml?¹ with a correlation coefficient of 0.998 and a detection limit of 25 ng ml?¹ (signal/noise=3). The designed immunosensor was stable for 1 month. PMID:22245258

Zarei, Hajar; Ghourchian, Hedayatollah; Eskandari, Khadijeh; Zeinali, Majid

2012-02-15

213

Analysis of Carbon Nanotube Field-Effect-Transistors (FETs)  

NASA Technical Reports Server (NTRS)

This five page presentation is grouped into 11 numbered viewgraphs, most of which contain one or more diagrams. Some of the diagrams are accompanied by captions, including: 2) Nanotube FET by Delft, IBM; 3) Nanotube FET/Standard MOSFET; 5) Saturation with carrier-carrier; 7) Electronic properties of carbon nanotube; 8) Theoretical nanotube FET characteristics; 11) Summary: Delft and IBM nanotube FET analysis.

Yamada, Toshishige

1999-01-01

214

Carbon nanotube temperature and pressure sensors  

DOEpatents

The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

Ivanov, Ilia N; Geohegan, David Bruce

2013-10-29

215

Growth of Carbon Nanotubes on Metallic Superalloys  

NASA Astrophysics Data System (ADS)

There are several advantages of growing carbon nanotubes (CNT) directly on bulk metallic substrates, for example in the formation of robust CNT-metal contacts during growth. Recently, we have shown that multi-wall carbon nanotubes can be grown on Inconel 600, a super alloy, using vapor phase catalyst delivery. The single-step growth of high-quality aligned nanotubes (comparable to those grown on SiO2 substrates) show encouraging electrical and mechanical properties. The in situ growth opens up a large number of possibilities for nanotube-based devices. Here, we present detailed investigations on the kinetics of the growth under various experimental conditions, and analyze the nanotube growth mechanism on the generic super alloy systems in the framework of our investigations.

Talapatra, Saikat; Kar, Swastik; Pal, Sunil; Gopal, Pethuraja; Ci, Lijie; Vajtai, Robert; Ajayan, Pulickel

2007-03-01

216

Functionalized carbon nanotubes: biomedical applications  

PubMed Central

Carbon nanotubes (CNTs) are emerging as novel nanomaterials for various biomedical applications. CNTs can be used to deliver a variety of therapeutic agents, including biomolecules, to the target disease sites. In addition, their unparalleled optical and electrical properties make them excellent candidates for bioimaging and other biomedical applications. However, the high cytotoxicity of CNTs limits their use in humans and many biological systems. The biocompatibility and low cytotoxicity of CNTs are attributed to size, dose, duration, testing systems, and surface functionalization. The functionalization of CNTs improves their solubility and biocompatibility and alters their cellular interaction pathways, resulting in much-reduced cytotoxic effects. Functionalized CNTs are promising novel materials for a variety of biomedical applications. These potential applications are particularly enhanced by their ability to penetrate biological membranes with relatively low cytotoxicity. This review is directed towards the overview of CNTs and their functionalization for biomedical applications with minimal cytotoxicity. PMID:23091380

Vardharajula, Sandhya; Ali, Sk Z; Tiwari, Pooja M; Ero?lu, Erdal; Vig, Komal; Dennis, Vida A; Singh, Shree R

2012-01-01

217

Fundamental optical processes in armchair carbon nanotubes  

NASA Astrophysics Data System (ADS)

Single-wall carbon nanotubes provide ideal model one-dimensional (1-D) condensed matter systems in which to address fundamental questions in many-body physics, while, at the same time, they are leading candidates for building blocks in nanoscale optoelectronic circuits. Much attention has been recently paid to their optical properties, arising from 1-D excitons and phonons, which have been revealed via photoluminescence, Raman scattering, and ultrafast optical spectroscopy of semiconducting carbon nanotubes. On the other hand, dynamical properties of metallic nanotubes have been poorly explored, although they are expected to provide a novel setting for the study of electron-hole pairs in the presence of degenerate 1-D electrons. In particular, (n,n)-chirality, or armchair, metallic nanotubes are truly gapless with massless carriers, ideally suited for dynamical studies of Tomonaga-Luttinger liquids. Unfortunately, progress towards such studies has been slowed by the inherent problem of nanotube synthesis whereby both semiconducting and metallic nanotubes are produced. Here, we use post-synthesis separation methods based on density gradient ultracentrifugation and DNA-based ion-exchange chromatography to produce aqueous suspensions strongly enriched in armchair nanotubes. Through resonant Raman spectroscopy of the radial breathing mode phonons, we provide macroscopic and unambiguous evidence that density gradient ultracentrifugation can enrich ensemble samples in armchair nanotubes. Furthermore, using conventional, optical absorption spectroscopy in the near-infrared and visible range, we show that interband absorption in armchair nanotubes is strongly excitonic. Lastly, by examining the G-band mode in Raman spectra, we determine that observation of the broad, lower frequency (G-) feature is a result of resonance with non-armchair ``metallic'' nanotubes. These findings regarding the fundamental optical absorption and scattering processes in metallic carbon nanotubes lay the foundation for further spectroscopic studies to probe many-body physical phenomena in one dimension.

Hároz, Erik H.; Duque, Juan G.; Tu, Xiaomin; Zheng, Ming; Hight Walker, Angela R.; Hauge, Robert H.; Doorn, Stephen K.; Kono, Junichiro

2013-01-01

218

Carbon nanotubes for biomedical imaging: the recent advances.  

PubMed

This article reviews the latest progresses regarding the applications of carbon nanotubes (CNTs), including single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs), as multifunctional nano-probes for biomedical imaging. Utilizing the intrinsic band-gap fluorescence of semi-conducting single-walled carbon nanotubes (SWNTs), fluorescence imaging in the near infrared II (NIR-II) region with enhanced tissue penetration and spatial resolution has shown great promise in recent years. Raman imaging based on the resonance Raman scattering of SWNTs has also been explored by a number of groups for in vitro and in vivo imaging of biological samples. The strong absorbance of CNTs in the NIR region can be used for photoacoustic imaging, and their photoacoustic signals can be dramatically enhanced by adding organic dyes, or coating with gold shells. Taking advantages of metal nanoparticle impurities attached to nanotubes, CNTs can also serve as a T2-contrast agent in magnetic resonance (MR) imaging. In addition, when labeled with radioactive isotopes, many groups have developed nuclear imaging with functionalized CNTs. Therefore CNTs are unique imaging probes with great potential in biomedical multimodal imaging. PMID:24184130

Gong, Hua; Peng, Rui; Liu, Zhuang

2013-12-01

219

Hydrogen Raman shifts in carbon nanotubes from molecular dynamics simulation  

E-print Network

Hydrogen Raman shifts in carbon nanotubes from molecular dynamics simulation S.J.V. Frankland *, D hydrogen in individual single-shell carbon nanotubes and nanotube ropes using a semiclassical model. The calculations predict that isolated hydrogen molecules inside of nanotubes have a Raman frequency that increases

Brenner, Donald W.

220

Carbon nanotube reinforced polyacrylonitrile and poly(etherketone) fibers  

Microsoft Academic Search

The graphitic nature, continuous structure, and high mechanical properties of carbon nanotubes (CNTs) make them good candidate for reinforcing polymer fiber. The different types of CNTs including single-wall carbon nanotubes (SWNTs), few-wall carbon nanotubes (FWNTs), and multi-wall carbon nanotubes (MWNTs), and carbon nanofibers (CNFs) differ in terms of their diameter and number of graphitic walls. The desire has been to

Rahul Jain

2009-01-01

221

Polymerization initated at sidewalls of carbon nanotubes  

NASA Technical Reports Server (NTRS)

The present invention is directed to aryl halide (such as aryl bromide) functionalized carbon nanotubes that can be utilized in anionic polymerization processes to form polymer-carbon nanotube materials with improved dispersion ability in polymer matrices. In this process the aryl halide is reacted with an alkyllithium species or is reacted with a metal to replace the aryl-bromine bond with an aryl-lithium or aryl-metal bond, respectively. It has further been discovered that other functionalized carbon nanotubes, after deprotonation with a deprotonation agent, can similarly be utilized in anionic polymerization processes to form polymer-carbon nanotube materials. Additionally or alternatively, a ring opening polymerization process can be performed. The resultant materials can be used by themselves due to their enhanced strength and reinforcement ability when compared to their unbound polymer analogs. Additionally, these materials can also be blended with pre-formed polymers to establish compatibility and enhanced dispersion of nanotubes in otherwise hard to disperse matrices resulting in significantly improved material properties. The resultant polymer-carbon nanotube materials can also be used in drug delivery processes due to their improved dispersion ability and biodegradability, and can also be used for scaffolding to promote cellular growth of tissue.

Tour, James M. (Inventor); Hudson, Jared L. (Inventor); Krishnamoorti, Ramanan (Inventor); Yurekli, Koray (Inventor); Mitchell, Cynthia A. (Inventor)

2011-01-01

222

Development of carbon nanotubes/CoFe2O4 magnetic hybrid material for removal of tetrabromobisphenol A and Pb(II).  

PubMed

Multi-walled carbon nanotubes (MWCNTs) coated with magnetic amino-modified CoFe2O4 (CoFe2O4-NH2) nanoparticles (denoted as MNP) were prepared via a simple one-pot polyol method. The MNP composite was further modified with chitosan (CTS) to obtain a chitosan-functionalized MWCNT/CoFe2O4-NH2 hybrid material (MNP-CTS). The obtained hybrid materials were characterized by Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectrogram (FT-IR) Analysis and X-ray Photoelectron Spectroscopy (XPS) Analysis, Vibrating Sample Magnetometer (VSM) Analysis and the Brunauer-Emmett-Teller (BET) surface area method, respectively. The composites were tested as adsorbents for tetrabromobisphenol A (TBBPA) and Pb(II), and were investigated using a pseudo-second-order model. The adsorption of TBBPA was well represented by the Freundlich isotherm; the Langmuir model better described Pb(II) absorption. MNP-CTS adsorbed both TBBPA and Pb(II) (maximum adsorption capacities of 42.48 and 140.1mgg(-1), respectively) better than did MNP without CTS. Magnetic composite particles with adsorbed TBBPA and Pb(II) could be regenerated using 0.2M NaOH solution and were separable from liquid media using a magnetic field. PMID:24342050

Zhou, Lincheng; Ji, Liqin; Ma, Peng-Cheng; Shao, Yanming; Zhang, He; Gao, Weijie; Li, Yanfeng

2014-01-30

223

Fabrication of a magnet-assisted alignment device for the amperometric detection of capillary electrophoresis using a carbon nanotube/polypropylene composite electrode.  

PubMed

A magnet-assisted alignment device was designed and fabricated for the amperometric detection of CE. It mainly consisted of a magnet-containing electrode holder, a capillary-based microdisc detection electrode, a detection cell, and a micrometer adjuster. To demonstrate the feasibility and performance of the alignment device, it was used in combination with a carbon nanotube/polypropylene (CNT/PP) composite electrode for the determination of p-phenylenediamine, m-aminophenol, and m-dihydroxybenzene in commercial hair dye by CE. The CNT-based electrode was fabricated by packing a melt mixture of CNTs and PP in a piece of fused silica capillary under heat, offering significantly lower operating potentials, substantially enhanced signal-to-noise characteristics, and high resistance to surface fouling. Because magnetic force was employed to move the detection electrode, the alignment system was significantly simplified. It is characterized by simple design and fabrication, high alignment reproducibility, reduced alignment time, and low cost. Both the alignment device and the CNT/PP composite electrode should find a wide range of applications in microchip CE, flowing injection analysis, and other microfluidic analysis systems. PMID:23161656

Xu, Junchao; Zhang, Luyan; Chen, Gang

2013-07-01

224

Carbon Nanotube Templated Microfabrication of Porous Silicon-Carbon Materials  

NASA Astrophysics Data System (ADS)

Carbon nanotube templated microfabrication (CNT-M) of porous materials is demonstrated. Partial chemical infiltration of three dimensional carbon nanotube structures with silicon resulted in a mechanically robust material, precisely structured from the 10 nm scale to the 100 micron scale. Nanoscale dimensions are determined by the diameter and spacing of the resulting silicon/carbon nanotubes while the microscale dimensions are controlled by lithographic patterning of the CNT growth catalyst. We demonstrate the utility of this hierarchical structuring approach by using CNT-M to fabricate thin layer chromatography (TLC) separations media with precise microscale channels for fluid flow control and nanoscale porosity for high analyte capacity.

Song, Jun; Jensen, David; Dadson, Andrew; Vail, Michael; Linford, Matthew; Vanfleet, Richard; Davis, Robert

2010-10-01

225

Carbon Nanotube and Graphene Nanoelectromechanical Systems  

NASA Astrophysics Data System (ADS)

One-dimensional and two-dimensional forms of carbon are composed of sp 2-hybridized carbon atoms arranged in a regular hexagonal, honeycomb lattice. The two-dimensional form, called graphene, is a single atomic layer of hexagonally-bonded carbon atoms. The one-dimensional form, known as a carbon nanotube, can be conceptualized as a rectangular piece of graphene wrapped into a seamless, high-aspect-ratio cylinder or tube. This dissertation addresses the physics and applied physics of these one and two-dimensional carbon allotropes in nanoelectromechanical systems (NEMS). First, we give a theoretical background on the electrodynamics and mechanics of carbon nanotube NEMS. We then describe basic experimental techniques, such as electron and scanning probe microscopy, that we then use to probe static and dynamic mechanical and electronic behavior of the carbon nanotube NEMS. For example, we observe and control non-linear beam bending and single-electron quantum tunneling effects in carbon nanotube resonators. We then describe parametric amplification, self-oscillation behavior, and dynamic, non-linear effects in carbon nanotube mechanical resonators. We also report a novel approach to fabricate carbon nanotube atomic force microscopy (AFM) probes, and show that they can lead to exceptional lateral resolution enhancement in AFM when imaging both hard and soft (biological) materials. Finally, we describe novel fabrication techniques for large-area, suspended graphene membranes, and utilize these membranes as TEM-transparent, AFM-compatible, NEMS resonators. Laser-driven mechanical vibrations of the graphene resonators are detected by optical interferometry and several vibration harmonics are observed. A degeneracy splitting is observed in the vibrational modes of square-geometry resonators. We then attribute the observed degeneracy splitting to local mass inhomogeneities and membrane defects, and find good overall agreement with the developed theoretical model.

Aleman, Benjamin Jose

226

Carbon nanotube based biomedical agents for heating, temperature sensoring and drug delivery  

E-print Network

Due to their extraordinary physical and chemical properties carbon nanotubes reveal a promising potential as biomedical agents for heating, temperature sensoring and drug delivery on the cellular level. Filling carbon nanotubes with tailored materials realises nanoscaled containers in which the active content is encapsulated by a protecting carbon shell. We describe different synthesis routes and show the structural and magnetic properties of carbon nanotubes. In particular, the filling with magnetic materials offers the potential for hyperthermia applications while the insertion of NMR active substances allows the usage as markers and sensors. The potential of carbon nanotubes for biomedical applications is highlighted by hyperthermia studies which prove their applicability for local in-situ heating. In addition we have shown that a non-invasive temperature control by virtue of a carbon-wrapped nanoscaled thermometer and filling with anti-cancer drugs is possible.

Klingeler, Ruediger; Buechner, Bernd

2009-01-01

227

Electrochemical storage of energy in carbon nanotubes and nanostructured carbons  

Microsoft Academic Search

Possibilities of electrochemical energy conversion using carbon nanotubes and related materials in various systems, such as lithium batteries, supercapacitors, hydrogen storage, are considered. It is shown that for these applications the electrochemical properties of multiwalled (MWNTs) and single walled (SWNTs) nanotubes are essentially dominated by their mesoporous character. During lithium insertion into nanotubular materials a high irreversible capacity Cirr (from

Elzbieta Frackowiak; François Béguin

2002-01-01

228

Release characteristics of selected carbon nanotube polymer composites  

EPA Science Inventory

Multi-walled carbon nanotubes (MWCNTs) are commonly used in polymer formulations to improve strength, conductivity, and other attributes. A developing concern is the potential for carbon nanotube polymer nanocomposites to release nanoparticles into the environment as the polymer ...

229

Carbon Nanotube Reinforced Polymers for Radiation Shielding Applications  

NASA Technical Reports Server (NTRS)

This viewgraph presentation provides information on the use of Extrusion Freeform Fabrication (EEF) for the fabrication of carbon nanotubes. The presentation addresses TGA analysis, Raman spectroscopy, radiation tests, and mechanical properties of the carbon nanotubes.

Thibeault, S. (Technical Monitor); Vaidyanathan, Ranji

2004-01-01

230

Irradiation Stability of Carbon Nanotubes and Related Materials  

E-print Network

Application of carbon nanotubes (CNTs) in various fields demands a thorough investigation of their stability under irradiation. Open structure, ability to reorganize and heal defects, and large surface-to-volume ratio of carbon nanotubes affect...

Aitkaliyeva, Assel 1985-

2012-09-28

231

New carbon nanotube antenna array simulation and fabrication  

NASA Astrophysics Data System (ADS)

A novel THz antenna structure, made of carbon nanotube arrays is suggested. Using CST MICROWAVE STUDIO (CST MWS), the capabilities of carbon nanotube terahertz (THz) antenna arrays have been simulated and this CNT antenna array has been fabricated.

Zareie, Hosein; Davoudzadeh, Nima; Koohsorkhi, Javad; Mohajerzadeh, Shamsoddin; Rouhi, Nima

2009-03-01

232

Non-destructive testing of a carbon-nanotube-reinforced composite using HTS-SQUID and electromagnetic techniques  

NASA Astrophysics Data System (ADS)

The correlation between electrical conductivity and magnetic field response, due to multi-walled carbon nanotubes' (MWCNTs) distribution within the polymer matrix, has been demonstrated using a contactless and non-destructive technique. Multi-walled carbon nanotubes, both buckypaper and reinforced epoxy matrix specimens with different nanotube percentages, have been inspected using the eddy current technique based on an HTc SQUID magnetometer. The SQUID magnetic field response, due to the nanotube distribution, has been compared with the thermographic technique results. Moreover, the electrical conductivity of nanotube-reinforced composites and buckypaper has been carried out by using the Van der Pauw method.

Bonavolontà, C.; Valentino, M.; Meola, C.; Carlomagno, G. M.; Volponi, R.; Rosca, I. D.

2009-09-01

233

Investigation of superconductivity in the single-walled carbon nanotubes  

Microsoft Academic Search

Superconductivity in the single-walled carbon nanotubes is investigated. First, effect of diameter increasing on the clean systems critical temperature, Tc, is calculated. Then effect of impurity doping on the reduction of critical temperature Tc, of single-walled carbon nanotubes, is discussed. Our calculations illustrate that metallic zigzag single-walled carbon nanotubes have higher Tc than armchair single-walled carbon nanotubes with approximately same

Rostam Moradian; Ali Fathalian

2008-01-01

234

Random telegraph signals and noise behaviors in carbon nanotube transistors  

NASA Astrophysics Data System (ADS)

A random telegraph signal appears at a smaller absolute gate bias for a larger absolute drain-source bias in a carbon nanotube transistor. Its mechanism is attributed to a defect located in the drain side of the Schottky barrier carbon nanotube transistor with Ti /Au as contact material. Furthermore, room temperature random telegraph signal is presented for both semiconducting and metallic carbon nanotubes, indicating the need to include random telegraph signal as a noise source for carbon nanotube transistors.

Liu, Fei; Wang, Kang L.; Zhang, Daihua; Zhou, Chongwu

2006-12-01

235

Functionalization of carbon nanotubes by water plasma.  

PubMed

Multiwall carbon nanotubes grown by plasma enhanced chemical vapour deposition were functionalized by H(2)O plasma treatment. Through a controlled functionalization process of the carbon nanotubes (CNTs) we were able to modify and tune their chemical reactivity, expanding the range of potential applications in the field of energy and environment. In particular, different oxygen groups were attached to the surfaces of the nanotubes (e.g. carboxyl, hydroxyl and carbonyl), which changed their physicochemical properties. In order to optimize the main operational parameters of the H(2)O plasma treatment, pressure and power, a Box-Wilson experimental design was adopted. Analysis of the morphology, electrochemical properties and functional groups attached to the surfaces of the CNTs allowed us to determine which treatment conditions were suitable for different applications. After water plasma treatment the specific capacitance of the nanotubes increased from 23 up to 68 F g(-1) at a scan rate of 10 mV s(-1). PMID:22947598

Hussain, S; Amade, R; Jover, E; Bertran, E

2012-09-28

236

Narrow graphene nanoribbons from carbon nanotubes  

Microsoft Academic Search

Graphene nanoribbons (GNRs) are materials with properties distinct from those of other carbon allotropes. The all-semiconducting nature of sub-10-nm GNRs could bypass the problem of the extreme chirality dependence of the metal or semiconductor nature of carbon nanotubes (CNTs) in future electronics. Currently, making GNRs using lithographic, chemical or sonochemical methods is challenging. It is difficult to obtain GNRs with

Liying Jiao; Li Zhang; Xinran Wang; Georgi Diankov; Hongjie Dai

2009-01-01

237

Nanotubes and Other Forms of Carbon  

NSDL National Science Digital Library

This set of videos, from the University of Wisconsin, show visualizations of the forms of carbon: graphite, graphine, diamond, fullerene, and nanotube. For each of the these forms, a model shows how the carbon atoms fit together to produce the arrangement of each.

2009-05-16

238

Incorporation of nitrogen in carbon nanotubes  

Microsoft Academic Search

Nitrogen-doped carbon nanotubes were obtained by the arc-discharge technique in a helium–nitrogen atmosphere and using iron–nickel–cobalt catalysts, The samples were analyzed using spectroscopic techniques (Raman, EELS, X-ray photoelectron spectroscopy) and transmission electron microscopy (TEM). Pure helium atmosphere conditions led to bundles of single-wall nanotubes with diameters of ?1.5 nm. The presence of nitrogen during tube formation produced irregular and thickly

R. Droppa; P Hammer; A. C. M Carvalho; M. C dos Santos; F Alvarez

2002-01-01

239

Solid state growth mechanisms for carbon nanotubes  

Microsoft Academic Search

The mechanisms by which carbon nanotubes nucleate and grow remain poorly understood. This paper reviews the models which have been proposed to explain nanotube growth in the arc-evaporation and laser-vaporisation processes. Many of the early models assumed that growth is a gas phase phenomenon but there is growing experimental evidence that the formation of both multiwalled and single-walled tubes involves

Peter J. F. Harris; J. J. Thomson

2007-01-01

240

Carbon Nanotube Polymer Composites While there are limitless  

E-print Network

Carbon Nanotube Polymer Composites Figure1 Figure2 While there are limitless applications of the composites in fig. 1 contain 0.26 wt% carbon nanotubes. The dark sample on the bottom right was made by melt blending 0.26% carbon nanotubes with the PMMA in a Banbury mixer. This illustrates the dramatic effect

Harmon, Julie P.

241

Carbon nanotube micro-electrodes for neuronal interfacing  

E-print Network

Carbon nanotube micro-electrodes for neuronal interfacing E. Ben-Jacoba and Y. Hanein*b DOI: 10.1039/b805878b This article highlights our recent progress in developing carbon nanotube based electrodes for neurochip applications. By integrating carbon nanotube growth with standard micro- fabrication techniques we

Jacob, Eshel Ben

242

Extrapolated f for carbon nanotube field-effect transistors  

E-print Network

Extrapolated f max for carbon nanotube field-effect transistors This article has been downloaded.1088/0957-4484/17/1/051 Extrapolated fmax for carbon nanotube field-effect transistors L C Castro and D L Pulfrey Department frequency of carbon nanotube field-effect transistors. The expressions are shown to be applicable over wide

Pulfrey, David L.

243

A phase-stabilized carbon nanotube fiber laser frequency comb  

E-print Network

A phase-stabilized carbon nanotube fiber laser frequency comb Jinkang Lim1 , Kevin Knabe1 , Karl A by a 167 MHz repetition frequency erbium-doped fiber ring laser using a carbon nanotube saturable absorber error on the carrier envelope offset frequency of 0.35 radians. The carbon nanotube fiber laser comb

Washburn, Brian

244

Broadband Photodetector Based on Carbon Nanotube Fibers Simon Lee,1  

E-print Network

UG-30 Broadband Photodetector Based on Carbon Nanotube Fibers Simon Lee,1 Xuan Wang absorption properties of the carbon nanotube fibers generate a thermal distribution across the length of applications of carbon nanotubes has been constantly expanding since its inception. From being a copper wire

245

Characterization of single wall carbon nanotubes by nonane preadsorption  

E-print Network

Characterization of single wall carbon nanotubes by nonane preadsorption Oleg Byl a , Jie Liu b The preferential blocking of the interior adsorption sites of single walled carbon nanotubes (SWNTs) by n the result of our study of nitro- gen adsorption on single walled carbon nanotubes where the interior sites

Liu, Jie

246

Single-Walle 4. Single-Walled Carbon Nanotubes  

E-print Network

105 Single-Walle 4. Single-Walled Carbon Nanotubes Sebastien Nanot, Nicholas A. Thompson, Ji Single-walled carbon nanotubes (SWCNTs) are hol- low, long cylinders with extremely large aspect ratios classified into single-walled and multi- walled nanotubes. Single-walled carbon nano- tubes, the subject

Kono, Junichiro

247

PREPARATION OF SINGLE-WALLED CARBON NANOTUBE SAMPLES FOR MICROPHOTOLUMINESCENCE  

E-print Network

PREPARATION OF SINGLE-WALLED CARBON NANOTUBE SAMPLES FOR MICROPHOTOLUMINESCENCE C. Martinez1, 2 , T the photoluminescence (PL) signal emitted from individual single-walled carbon nanotubes (SWCNTs). PL from SWCNTs & Education Program (OISE-0968405). Preparation of Single-Walled Carbon Nanotube Samples

Mellor-Crummey, John

248

Symmetry of electron diffraction from single-walled carbon nanotubes  

E-print Network

Symmetry of electron diffraction from single-walled carbon nanotubes Zejian Liu a , Lu-Chang Qin a patterns of the single-walled carbon nanotube always possess 2mm symmetry. We have also analyzed of a single-walled carbon nanotube generally does not have mirror symmetry per- pendicular to the tubule axis

Qin, Lu-Chang

249

Individual Single-Walled Carbon Nanotubes as Nanoelectrodes for  

E-print Network

Individual Single-Walled Carbon Nanotubes as Nanoelectrodes for Electrochemistry Iddo Heller, Jing single-walled carbon nanotubes (SWNTs) as nanoelectrodes for electrochemistry. SWNTs were contacted data.6 Here we explore the use of individual single-walled carbon nanotubes (SWNTs) as electrodes

Dekker, Cees

250

Effective wall thickness of a single-walled carbon nanotube  

Microsoft Academic Search

This paper investigates the effective wall thickness of a single-walled carbon nanotube, a critical quantity for any research in mechanics and property characterization of carbon nanotubes. To this end, the response of a bundle of single-walled carbon nanotubes to external hydrostatic pressure was modeled using the ring theory of continuum mechanics. The model predicted that the equivalent thickness should be

T. Vodenitcharova; L. C. Zhang

2003-01-01

251

Photoconductivity of single-walled carbon nanotubes under CW illumination.  

E-print Network

Photoconductivity of single-walled carbon nanotubes under CW illumination. I. A. Levitsky Emitech placed on the electronic and optical properties of single-walled carbon nanotubes (SWNTs) is associated of single-walled carbon nanotubes in the NIR and far-IR spectral range. II. EXPERIMENT SWNTs were

Euler, William B.

252

Enhancement of semiconducting single-wall carbon nanotubes photoluminescence  

E-print Network

Enhancement of semiconducting single-wall carbon nanotubes photoluminescence Etienne Gaufr`es1.vivien@u-psud.fr Photoluminescence properties of semiconducting single wall carbon nanotubes (s-SWNT) thin films with different metallic single wall carbon nanotubes (m-SWNT) concentrations are reported. s-SWNT purified samples are ob

Boyer, Edmond

253

Simulations of nanosensors based on single walled carbon nanotubes  

E-print Network

Simulations of nanosensors based on single walled carbon nanotubes Polina Pine1, Yuval E. Yaish2. The potential of single-walled carbon nanotubes as mass sensors is examined. The change in mass leads Chowdhury et al [17] examined the potential of single-walled carbon nanotubes (SWCNTs) as mass sensors

Adler, Joan

254

Optical microcavity with semiconducting single-wall carbon nanotubes  

E-print Network

Optical microcavity with semiconducting single- wall carbon nanotubes Etienne Gaufrès,1 Nicolas-Perot microcavities based on semiconducting single-wall carbon nanotubes with a quality factor of 160. We. Meunier, P. Desjardins, D. Ménard and R. Martel, "Electroluminescence from single-wall carbon nanotube

Paris-Sud XI, Université de

255

Enhanced Cellular Activation with Single Walled Carbon Nanotube Bundles  

E-print Network

Enhanced Cellular Activation with Single Walled Carbon Nanotube Bundles Presenting Antibody Stimuli the body using single walled carbon nanotube (SWNT) bundles presenting antibody stimuli. Owing to the large of lymphocytes, useful for basic science applications and clinical immunotherapy. Single walled carbon nanotubes

Fahmy, Tarek

256

Raman Measurements on Electrochemically Doped Single-Walled Carbon Nanotubes  

E-print Network

Raman Measurements on Electrochemically Doped Single-Walled Carbon Nanotubes P. M. Rafailov, M and studied the Raman response of electro- chemically doped single-walled carbon nanotubes (SWNT) using is proposed. Introduction. Single-wall carbon nanotubes (SWNT) are novel one-dimensional nanostructures

Nabben, Reinhard

257

Electrochemical and Raman measurements on single-walled carbon nanotubes  

E-print Network

Electrochemical and Raman measurements on single-walled carbon nanotubes M. Stoll a,*, P. Introduction Single-wall carbon nanotubes (SWNTs) are novel one-dimensional nanostructures with prom- ising performed on a carbon nanotube mat as a working electrode using different salt solutions. The gravimetric

Nabben, Reinhard

258

Carbon Nanotube FETs as Chemical Sensors  

NASA Astrophysics Data System (ADS)

Exposure to chemical molecules can greatly change the conductance of carbon nanotube FETs (CNFETs). The underlying sensing mechanisms may involve changes in the properties of the interface between nanotube and electrode [1], as well as the nanotube bulk response to chemical molecules [2]. We fabricate CNFETs by standard photolithographic techniques, both for catalyst and contact patterning [3], and characterize their response, i.e. changes in the threshold voltage and saturated conductance, upon exposure of the whole device to chemical molecules, such as nitrogen dioxide and ammonia. We find that nitrogen dioxide only changes the threshold voltage, whereas ammonia changes both the threshold voltage and the saturated conductance. We plan to protect the carbon-nanotube/electrode interfaces and expose only the carbon nanotube to the same concentration of chemical molecules, to measure the contribution to the response due only to the bulk of the nanotube and distinguish between different sensing mechanisms. This work is supported by the ACS (PRF-39152-G5M) and the NSF (DMR-0239721). [1] V.Derycke, R. Martel, J. Appenzeller and Ph. Avouris, Appl.Phys.Lett., 80, 2773 (2002). [2] J. Kong, etc., Science 287, 622 (2000). [3] A. Tselev, K. Hatton, M. S. Fuhrer, M. Paranjape and P. Barbara, Nanotechnology 15, 1475 (2004).

Zhang, Jian

2005-03-01

259

Does water dope carbon nanotubes?  

NASA Astrophysics Data System (ADS)

We calculate the long-range perturbation to the electronic charge density of carbon nanotubes (CNTs) as a result of the physisorption of a water molecule. We find that the dominant effect is a charge redistribution in the CNT due to polarisation caused by the dipole moment of the water molecule. The charge redistribution is found to occur over a length-scale greater than 30 Å, highlighting the need for large-scale simulations. By comparing our fully first-principles calculations to ones in which the perturbation due to a water molecule is treated using a classical electrostatic model, we estimate that the charge transfer between CNT and water is negligible (no more than 10-4 e per water molecule). We therefore conclude that water does not significantly dope CNTs, a conclusion that is consistent with the poor alignment of the relevant energy levels of the water molecule and CNT. Previous calculations that suggest water n-dopes CNTs are likely due to the misinterpretation of Mulliken charge partitioning in small supercells.

Bell, Robert A.; Payne, Michael C.; Mostofi, Arash A.

2014-10-01

260

Cytotoxicity, cytocompatibility, cell-labeling efficiency, and in vitro cellular magnetic resonance imaging of gadolinium-catalyzed single-walled carbon nanotubes  

PubMed Central

Cell tracking by magnetic resonance imaging (MRI) is an emerging technique that typically requires the use of MRI contrast agents (CAs). A MRI CA for cellular imaging should label cells efficiently at potentially safe concentrations, have high relaxivity, and not affect the cellular machinery. In this article, we report the cytotoxicity, cytocompatibility, and cell labeling efficiency in NIH/3T3 fibroblasts of novel, single-walled carbon nanotubes synthesized using gadolinium nano-particles as catalysts (Gd-SWCNTs). Cells incubated with the Gd-SWCNT showed a dose- (50–100 ?g/mL nanotube concentration) and time- (12–48 h) dependent decrease in viability. 30% cell death was observed for cells incubated with Gd-SWCNTs at the maximum dose of 100 ?g/mL for 48 h. Cells incubated with the Gd-SWCNTs at concentrations between 1–10 ?g/mL for 48 h showed no change in viability or proliferation compared to untreated controls. Additionally, at these potentially safe concentrations, up to 48 h, the cells showed no phosphatidyl serine externalization (pre-apoptotic condition), caspase-3 activity (point of no return for apoptosis), genetic damage, or changes in their division cycle. Localization of Gd-SWCNTs within the cells was confirmed by transmission electron microscopy (TEM) and Raman microscopy, and these results show 100% cell labeling efficiency. Elemental analysis also indicates significant uptake of Gd-SWCNTs by the cells (108–109 Gd3+ ions per cell). Finally, T1-weighted MRI at 3 T of Gd-SWCNT-labelled cells show up to a four-fold increase in MR signal intensities as compared to untreated cells. These results indicate that Gd-SWCNTs label cells efficiently at potentially safe concentrations, and enhance MRI contrast without any structural damage to the cells. PMID:23686792

Avti, Pramod K.; Caparelli, Elisabeth D.; Sitharaman, Balaji

2013-01-01

261

Horizontally aligned single-walled carbon nanotube field emitters fabricated on vertically aligned multi-walled carbon nanotube electrode arrays  

Microsoft Academic Search

Vertically aligned multi-walled carbon nanotube (MWCNT) arrays were fabricated on an anodic aluminum oxide membrane bonded to a Si wafer. After obtaining a protruding tip for the MWCNTs by etching away some oxide, they were used as electrodes in the fabrication of carbon nanotube field emitters. Long single-walled carbon nanotubes (SWCNTs) were spin coated on the MWCNT arrays of uniform

Hyun Young Jung; Sung Mi Jung; Jung Sang Suh

2008-01-01

262

Carbon nanotube-chalcogenide glass composite  

SciTech Connect

This article describes the preparation of multi-walled carbon nanotube-chalcogenide glass composite by direct synthesis and the melt-quenching method. The carbon nanotubes-chalcogenide glass composite was characterized by high-resolution transmission electron microscopy (HRTEM), TEM/energy-dispersive X-ray spectroscopy, low energy electron excited X-ray spectroscopy, Raman spectroscopy, spectroscopic ellipsometry, microhardness, and impedance spectroscopy. CNTs-AgAsS{sub 2} glass composite possess highly increased ionic conductivity, from {sigma}{sub 25} deg. C=4.38+-0.0438x10{sup -6} to {sigma}{sub 25} deg. C=6.57+-0.0657x10{sup -6} S cm{sup -1} and decreased refractive index from n=2.652 to 2.631 at the wavelength {lambda}=1.55 {mu}m. - Graphical abstract: Preparation of multi-walled carbon nanotube-doped chalcogenide glasses by direct synthesis and the melt-quenching method

Stehlik, Stepan; Orava, Jiri; Kohoutek, Tomas; Wagner, Tomas; Frumar, Miloslav [Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Legion's sq. 565, 53210 Pardubice (Czech Republic); Zima, Vitezslav [Joint Laboratory of Solid State Chemistry of the Institute of Macromolecular Chemistry Academy of Sciences, University of Pardubice, Studentska 84, 52310 Pardubice (Czech Republic); Hara, Toru; Matsui, Yoshio [High-Voltage Electron Microscopy Station, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Ueda, Kazuyuki [Nano High Tech Research Center, Toyota Technological Institute, Nagoya 468-8511 (Japan); Pumera, Martin, E-mail: pumera.martin@nims.go.j [International Center for Materials Nanoarchitectonics and Biomaterials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

2010-01-15

263

Modelling Carbon Nanotubes-Based Mediatorless Biosensor  

PubMed Central

This paper presents a mathematical model of carbon nanotubes-based mediatorless biosensor. The developed model is based on nonlinear non-stationary reaction-diffusion equations. The model involves four layers (compartments): a layer of enzyme solution entrapped on a terylene membrane, a layer of the single walled carbon nanotubes deposited on a perforated membrane, and an outer diffusion layer. The biosensor response and sensitivity are investigated by changing the model parameters with a special emphasis on the mediatorless transfer of the electrons in the layer of the enzyme-loaded carbon nanotubes. The numerical simulation at transient and steady state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data. The obtained agreement between the simulation results and the experimental data was admissible at different concentrations of the substrate. PMID:23012537

Baronas, Romas; Kulys, Juozas; Petrauskas, Karolis; Razumiene, Julija

2012-01-01

264

Carbon nanotubes in neuroregeneration and repair.  

PubMed

In the last decade, we have experienced an increasing interest and an improved understanding of the application of nanotechnology to the nervous system. The aim of such studies is that of developing future strategies for tissue repair to promote functional recovery after brain damage. In this framework, carbon nanotube based technologies are emerging as particularly innovative tools due to the outstanding physical properties of these nanomaterials together with their recently documented ability to interface neuronal circuits, synapses and membranes. This review will discuss the state of the art in carbon nanotube technology applied to the development of devices able to drive nerve tissue repair; we will highlight the most exciting findings addressing the impact of carbon nanotubes in nerve tissue engineering, focusing in particular on neuronal differentiation, growth and network reconstruction. PMID:23856411

Fabbro, Alessandra; Prato, Maurizio; Ballerini, Laura

2013-12-01

265

Orientational Growth of Carbon Nanotube for Applications  

NASA Technical Reports Server (NTRS)

Since the superior properties of multi-wall carbon nanotubes (MWCNT) could improve numerous devices such as electronics and sensors, many efforts have been made in investigating the growth mechanism of MWCNT to synthesize high quality MWCNT. Most applications require uniform aligned CNT. In this presentation, a directional growth of CNT will be reported. Carbon nanotubes are synthesized using thermal chemical vapor deposition. Temperature and pressure are two important growth parameters for fabricating carbon nanotubes. It is found that the nanotube diameter distribution mainly depends on the growth-temperature. With the substrate surface normal either along or against the gravity vector, different growth orientations of MWCNT are observed by scanning electron microscopy although the Raman spectra are similar for samples synthesized at different locations. The sizes of these carbon nanotubes in each sample are quite uniform and the length of the tube is up to several tens of micrometers. These results suggest the gravitation effects in the growth of long and small diameter CNT.

Zhu, Shen; Su, Ching-Hua; Cochrane, J. C.; Lehoczky, S.; Cui, Y.; Burger, A.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

266

Heat conduction in carbon nanotube materials: Strong effect of intrinsic thermal conductivity of carbon nanotubes  

E-print Network

Heat conduction in carbon nanotube materials: Strong effect of intrinsic thermal conductivity of the finite thermal conductivity kT of individual nanotubes on the conductivity k of the CNT materials.1063/1.4737903] Experimental measurements of thermal conductivity of individual CNTs, kT, reveal exceptionally high room

Zhigilei, Leonid V.

267

Carbon Nanotube-Enhanced Carbon-Phenenolic Ablator Material  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the use of PICA (phenolic impregnated carbon ablator) as the selected material for heat shielding for future earth return vehicles. It briefly reviews the manufacturing of PICA and the advantages for the use of heat shielding, and then explains the reason for using Carbon Nanotubes to improve strength of phenolic resin that binds carbon fibers together. It reviews the work being done to create a carbon nanotube enhanced PICA. Also shown are various micrographic images of the various PICA materials.

Kikolaev, P.; Stackpoole, M.; Fan, W.; Cruden, B. A.; Waid, M.; Moloney, P.; Arepalli, S.; Arnold, J.; Partridge, H.; Yowell, L.

2006-01-01

268

Lipid nanoscaffolds in carbon nanotube arrays  

NASA Astrophysics Data System (ADS)

We present the fabrication of lipid nanoscaffolds inside carbon nanotube arrays by employing the nanostructural self-assembly of lipid molecules. The nanoscaffolds are finely tunable into model biomembrane-like architectures (planar), soft nanochannels (cylindrical) or 3-dimensionally ordered continuous bilayer structures (cubic). Carbon nanotube arrays hosting the above nanoscaffolds are formed by packing of highly oriented multiwalled carbon nanotubes which facilitate the alignment of lipid nanostructures without requiring an external force. Furthermore, the lipid nanoscaffolds can be created under both dry and hydrated conditions. We show their direct application in reconstitution of egg proteins. Such nanoscaffolds find enormous potential in bio- and nano-technological fields.We present the fabrication of lipid nanoscaffolds inside carbon nanotube arrays by employing the nanostructural self-assembly of lipid molecules. The nanoscaffolds are finely tunable into model biomembrane-like architectures (planar), soft nanochannels (cylindrical) or 3-dimensionally ordered continuous bilayer structures (cubic). Carbon nanotube arrays hosting the above nanoscaffolds are formed by packing of highly oriented multiwalled carbon nanotubes which facilitate the alignment of lipid nanostructures without requiring an external force. Furthermore, the lipid nanoscaffolds can be created under both dry and hydrated conditions. We show their direct application in reconstitution of egg proteins. Such nanoscaffolds find enormous potential in bio- and nano-technological fields. Electronic supplementary information (ESI) available: Additional wide angle X-ray scattering (WAXS) data on the alignment of lipid nanostructures, control and time resolved 2-d images of egg ovalbumin encapsulation and a summary picture of the present work. See DOI: 10.1039/c3nr02068a

Paukner, Catharina; Koziol, Krzysztof K. K.; Kulkarni, Chandrashekhar V.

2013-09-01

269

Carbon nanotube-clamped metal atomic chain  

PubMed Central

Metal atomic chain (MAC) is an ultimate one-dimensional structure with unique physical properties, such as quantized conductance, colossal magnetic anisotropy, and quantized magnetoresistance. Therefore, MACs show great potential as possible components of nanoscale electronic and spintronic devices. However, MACs are usually suspended between two macroscale metallic electrodes; hence obvious technical barriers exist in the interconnection and integration of MACs. Here we report a carbon nanotube (CNT)-clamped MAC, where CNTs play the roles of both nanoconnector and electrodes. This nanostructure is prepared by in situ machining a metal-filled CNT, including peeling off carbon shells by spatially and elementally selective electron beam irradiation and further elongating the exposed metal nanorod. The microstructure and formation process of this CNT-clamped MAC are explored by both transmission electron microscopy observations and theoretical simulations. First-principles calculations indicate that strong covalent bonds are formed between the CNT and MAC. The electrical transport property of the CNT-clamped MAC was experimentally measured, and quantized conductance was observed. PMID:20427743

Tang, Dai-Ming; Yin, Li-Chang; Li, Feng; Liu, Chang; Yu, Wan-Jing; Hou, Peng-Xiang; Wu, Bo; Lee, Young-Hee; Ma, Xiu-Liang; Cheng, Hui-Ming

2010-01-01

270

Spontaneous Exciton Dissociation in Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Simultaneous photoluminescence and photocurrent measurements on individual single-walled carbon nanotubes reveal spontaneous dissociation of excitons into free electron-hole pairs. The correlation of luminescence intensity and photocurrent shows that a significant fraction of excitons are dissociating before recombination. Furthermore, the combination of optical and electrical signals also allows for extraction of the absorption cross section and the oscillator strength. Our observations explain the reasons why photoconductivity measurements in single-walled carbon nanotubes are straightforward despite the large exciton binding energies.

Kumamoto, Y.; Yoshida, M.; Ishii, A.; Yokoyama, A.; Shimada, T.; Kato, Y. K.

2014-03-01

271

Fluctuation broadening in carbon nanotube resonators  

PubMed Central

We simulated the behavior of suspended carbon nanotube resonators over a broad range of temperatures to explore the physics of semiflexible polymers in underdamped environments. We find that thermal fluctuations induce strong coupling between resonance modes. This effect leads to spectral fluctuations that readily account for the experimentally observed quality factors Q ? 100 at 300 K. Using a mean-field approach to describe fluctuations, we analytically calculate Q and frequency shifts in tensioned and buckled carbon nanotubes and find excellent agreement with simulations. PMID:23132940

Barnard, Arthur W.; Sazonova, Vera; van der Zande, Arend M.; McEuen, Paul L.

2012-01-01

272

Carbon nanotube fibers as torsion sensors  

NASA Astrophysics Data System (ADS)

Carbon nanotube fibers possess the ability to respond electrically to tensile loading. This research explores their electrical response to torsional loading; results demonstrate that applied twist compacts the fiber, resulting in increased electrical contact between carbon nanotubes. Shear strains in excess of 24% do not result in permanent changes in electrical resistance along uninfused fibers, while irreversible changes in electrical resistance arise from applied shear strains of 12.9% in epoxy infused fibers. Bulk shear modulus is approximated to be 0.40 ± 0.02 GPa for unreinforced and 2.79 ± 0.64 GPa for infused fibers.

Wu, A. S.; Nie, X.; Hudspeth, M. C.; Chen, W. W.; Chou, T.-W.; Lashmore, D. S.; Schauer, M. W.; Towle, E.; Rioux, J.

2012-05-01

273

Transport Through Carbon Nanotube Wires  

NASA Technical Reports Server (NTRS)

This viewgraph presentation gives an overview of the the current carrying capacity of nanotube wires. Information is given on the motivation for the research, models and assumptions, Bragg reflection and Zener tunneling effects, and the influence of defects. Results show that dI/dv versus V does not increase in a manner commensurate with the increase in the number of subbands; in small diameter nanotubes, Zener tunneling is ineffective; Zener tunneling contributes to current with increase in nanotube diameter; and the increase in dI/dV with bias is much smaller than the increase in the number of subbands.

Anantram, M. P.; Yan, Jerry (Technical Monitor)

2000-01-01

274

Titania carbon nanotube composites for enhanced photocatalysis  

NASA Astrophysics Data System (ADS)

Photocatalytic composites have been used for the past few decades in a wide range of applications. The most common application is the purification of air and water by removing toxic compounds. There is limited use however towards biocidal applications. Despite their high efficiency, photocatalytic materials are not comparable to the effectiveness of conventional biocidal compounds such as chlorine and alcoholic disinfectants. On the other hand, nearly a decade ago with the discovery of the carbon nanotubes a new vibrant scientific field emerged. Nanotubes are unique structures of carbon that posse amazing electrical, mechanical and thermal properties. In this research carbon nanotubes are used as photocatalytic enhancers. They were coated with anatase titania to form a composite material. Two different types of nanotubes (metallic versus non-metallic) were used and the photocatalytic activity was measured. The metallic tubes demonstrated exceptional photocatalytic properties, while non-metallic tubes had low photocatalytic efficiency. The reason for that difference was investigated and was the major focus of this research. The research concluded that the reasons for the high efficiency of the carbon nanotubes were (i) the metallic nature of the tubes and (ii) the possible bond between the titania coating and the underlying graphite layers (C-O-Ti). Since both composites had the same indications regarding the C-O-Ti bond, the metallic nature of the carbon nanotubes is believed to be the most dominant factor contributing to the enhancement of the photocatalysis. The composite material may have other potential applications such as for sensing and photovoltaic uses.

Pyrgiotakis, Georgios

275

Carbon Nanotube Membranes: Carbon Nanotube Membranes for Energy-Efficient Carbon Sequestration  

SciTech Connect

Broad Funding Opportunity Announcement Project: Porifera is developing carbon nanotube membranes that allow more efficient removal of CO2 from coal plant exhaust. Most of today’s carbon capture methods use chemical solvents, but capture methods that use membranes to draw CO2 out of exhaust gas are potentially more efficient and cost effective. Traditionally, membranes are limited by the rate at which they allow gas to flow through them and the amount of CO2 they can attract from the gas. Smooth support pores and the unique structure of Porifera’s carbon nanotube membranes allows them to be more permeable than other polymeric membranes, yet still selective enough for CO2 removal. This approach could overcome the barriers facing membrane-based approaches for capturing CO2 from coal plant exhausts.

None

2010-03-01

276

Designing electrochemical interfaces with functionalized magnetic nanoparticles and wrapped carbon nanotubes as platforms for the construction of high-performance bienzyme biosensors.  

PubMed

The design of a novel biosensing electrode surface, combining the advantages of magnetic ferrite nanoparticles (MNPs) functionalized with glutaraldehyde (GA) and poly(diallyldimethylammonium chloride) (PDDA)-coated multiwalled carbon nanotubes (MWCNTs) as platforms for the construction of high-performance multienzyme biosensors, is reported in this work. Before the immobilization of enzymes, GA-MNP/PDDA/MWCNT composites were prepared by wrapping of carboxylated MWCNTs with positively charged PDDA and interaction with GA-functionalized MNPs. The nanoconjugates were characterized by scanning electron microscopy (SEM) and electrochemistry. The electrode platform was used to construct a bienzyme biosensor for the determination of cholesterol, which implied coimmobilization of cholesterol oxidase (ChOx) and peroxidase (HRP) and the use of hydroquinone as redox mediator. Optimization of all variables involved in the preparation and analytical performance of the bienzyme electrode was accomplished. At an applied potential of -0.05 V, a linear calibration graph for cholesterol was obtained in the 0.01-0.95 mM concentration range. The detection limit (0.85 ?M), the apparent Michaelis-Menten constant (1.57 mM), the stability of the biosensor, and the calculated activation energy can be advantageously compared with the analytical characteristics of other CNT-based cholesterol biosensors reported in the literature. Analysis of human serum spiked with cholesterol at different concentration levels yielded recoveries between 100% and 103% PMID:21905724

Eguílaz, Marcos; Villalonga, Reynaldo; Yáñez-Sedeño, Paloma; Pingarrón, José M

2011-10-15

277

Atomic Force Microscopy of Single-Walled Carbon Nanotubes Using Carbon Nanotube Tip  

Microsoft Academic Search

We succeeded in observing individual single-walled carbon nanotubes (SWNTs) using an atomic force microscope (AFM) in the tapping mode by paying attention to the preparation of both samples and AFM tips. To disentangle the bundles of SWNTs, we added a small amount of amine into N,N-dimethylformamide. To achieve a high resolution in tapping-mode AFM imaging, we used carbon nanotube (CNT)

Nami Choi; Takayuki Uchihashi; Hidehiro Nishijima; Takao Ishida; Wataru Mizutani; Seiji Akita; Yoshikazu Nakayama; Mitsuru Ishikawa; Hiroshi Tokumoto

2000-01-01

278

Patching and Tearing Single-Wall Carbon-Nanotube Ropes into Multiwall Carbon Nanotubes  

Microsoft Academic Search

Bundles of single-wall carbon nanotubes (SWCNTs) coalesce forming multiwall carbon nanotubes (MWCNTs), containing from two to six nested tubes, under thermal treatment at high temperatures [(2200-2400) °C]. This structural transformation is confirmed by extensive molecular dynamics (MD) simulations. The simulations suggest a ``patching-and-tearing'' mechanism for the single-wall-to-multiwall transformation underlying the ``concerted'' coalescence of the tubes that begins with their polymerization.

María J. López; Angel Rubio; Julio A. Alonso; Serge Lefrant; Karine Méténier; Sylvie Bonnamy

2002-01-01

279

Supramolecular Self-Assembly of Lipid Derivatives on Carbon Nanotubes  

Microsoft Academic Search

Images of the assembly of surfactants and synthetic lipids on the surface of carbon nanotubes were obtained by transmission electron microscopy. Above the critical micellar concentration, sodium dodecyl sulfate (SDS) forms supramolecular structures made of rolled-up half-cylinders on the nanotube surface. Depending on the symmetry and the diameter of the carbon nanotube, we observed rings, helices, or double helices. Similar

Cyrille Richard; Fabrice Balavoine; Patrick Schultz; Thomas W. Ebbesen; Charles Mioskowski

2003-01-01

280

CARBON NANOTUBES IN MICROWAVE ENVIRONMENT-IGNITION AND RECONSTRUCTION  

EPA Science Inventory

The unusual property of single-walled carbon nanotubes (SWNT), multi-wall (MWNT) nanotubes and Buckminsterfullerene (C-60) is observed upon exposure to microwave-assisted ignition. Carbon nanotubes known for a range of mechanical and electronic properties because of their unique...

281

Exohydrogenated single-wall carbon nanotubes T. Yildirim,1  

E-print Network

Exohydrogenated single-wall carbon nanotubes T. Yildirim,1 O. Gu¨lseren,1,2 and S. Ciraci3 1 NIST exohydrogenated zigzag (n,0) and armchair (n,n) single-wall carbon nanotubes (CnHn), polyhedral molecules to the radius of a 8,8 nanotube, with binding energies proportional to 1/R. Attaching a single hydrogen to any

Yildirim, Taner

282

Improved synthesis of carbon nanotubes with junctions and of single-walled carbon nanotubes  

Microsoft Academic Search

Pyrolysis of thiophene over nickel nanoparticles dispersed on silica is shown to yield Y-junction carbon nanotubes with smaller\\u000a diameters than those obtained by the pyrolysis of organometallic-thiophene mixtures. In the presence of water vapour, the\\u000a pyrolysis of organometallic-hydrocarbon mixtures yields single-walled nanotubes, as well as relatively narrow-diameter carbon\\u000a nanotubes with Y-junctions. Pyrolysis of organometallic-hydrocarbon mixtures, in the absence of water

F. L. Deepak; A. Govindaraj; C. N. R. Rao

2006-01-01

283

Effective reinforcement in carbon nanotube-polymer composites.  

PubMed

Carbon nanotubes have mechanical properties that are far in excess of conventional fibrous materials used in engineering polymer composites. Effective reinforcement of polymers using carbon nanotubes is difficult due to poor dispersion and alignment of the nanotubes along the same axis as the applied force during composite loading. This paper reviews the mechanical properties of carbon nanotubes and their polymer composites to highlight how many previously prepared composites do not effectively use the excellent mechanical behaviour of the reinforcement. Nanomechanical tests using atomic force microscopy are carried out on simple uniaxially aligned carbon nanotube-reinforced polyvinyl alcohol (PVA) fibres prepared using electrospinning processes. Dispersion of the carbon nanotubes within the polymer is achieved using a surfactant. Young's modulus of these simple composites is shown to approach theoretically predicted values, indicating that the carbon nanotubes are effective reinforcements. However, the use of dispersant is also shown to lower Young's modulus of the electrospun PVA fibres. PMID:18192168

Wang, W; Ciselli, P; Kuznetsov, E; Peijs, T; Barber, A H

2008-05-13

284

Carbon Nanotube Inter and Intramolecular Logic Gates  

Microsoft Academic Search

Single wall carbon nanotubes (SWCNTs) have been used as the active channels of field effect transistors (FET). The next development step involves the integration of CNTFETs to form logic gates; the basic units of computers. For this we need to have both p- and n-type CNTFETs. However, without special treatment, the obtained CNTFETs are always p-type: the current carriers are

V. Derycke; R. Martel; J. Appenzeller; Ph. Avouris

2001-01-01

285

Carbon Nanotubes as Schottky Barrier Transistors  

Microsoft Academic Search

We show that carbon nanotube transistors operate as unconventional ``Schottky barrier transistors,'' in which transistor action occurs primarily by varying the contact resistance rather than the channel conductance. Transistor characteristics are calculated for both idealized and realistic geometries, and scaling behavior is demonstrated. Our results explain a variety of experimental observations, including the quite different effects of doping and adsorbed

S. Heinze; J. Tersoff; R. Martel; V. Derycke; J. Appenzeller; Ph. Avouris

2002-01-01

286

Carbon Nanotubes--the Route Toward Applications  

Microsoft Academic Search

Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects. Some of these applications are now realized in products. Others are demonstrated in early to advanced devices, and one, hydrogen storage, is clouded

Ray H. Baughman; Anvar A. Zakhidov; Walt A. de Heer

2002-01-01

287

Coulomb Drag in Multiwall Carbon Nanotubes  

E-print Network

Coulomb Drag in Multiwall Carbon Nanotubes Master Thesis in Physics Anders Mathias Lunde Niels Bohr Flensberg (at the Niels Bohr int., Copenhagen University). I will like to thank my supervisors . . . . . . . . . . . . . . . . . . . 52 3.3.1 The model of the coupled Boltzmann equati

Nygård, Jesper

288

Transparent and Flexible Carbon Nanotube Transistors  

E-print Network

Transparent and Flexible Carbon Nanotube Transistors E. Artukovic, M. Kaempgen, D. S. Hecht, S We report the fabrication of transparent and flexible transistors where both the bottom gate not influence the transmission in the visible spectral range. The quest for flexible and transparent transistors

Gruner, George

289

Synthesis of Carbon Nanotube (CNT) Composite Membranes  

PubMed Central

Carbon nanotubes are attractive approach for designing of new membranes for advanced molecular separation because of their unique transport properties and ability to mimic biological protein channels. In this work the synthetic approach for fabrication of carbon nanotubes (CNTs) composite membranes is presented. The method is based on growth of multi walled carbon nanotubes (MWCNT) using chemical vapour deposition (CVD) on the template of nanoporous alumina (PA) membranes. The influence of experimental conditions including carbon precursor, temperature, deposition time, and PA template on CNT growth process and quality of fabricated membranes was investigated. The synthesis of CNT/PA composites with controllable nanotube dimensions such as diameters (30–150 nm), and thickness (5–100 ?m), was demonstrated. The chemical composition and morphological characteristics of fabricated CNT/PA composite membranes were investigated by various characterisation techniques including scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDXS), high resolution transmission electron microscopy (HRTEM) and x-ray diffraction (XRD). Transport properties of prepared membranes were explored by diffusion of dye (Rose Bengal) used as model of hydrophilic transport molecule. PMID:24957494

Altalhi, Tariq; Ginic-Markovic, Milena; Han, Ninghui; Clarke, Stephen; Losic, Dusan

2011-01-01

290

Synthesis of Carbon Nanotube (CNT) Composite Membranes.  

PubMed

Carbon nanotubes are attractive approach for designing of new membranes for advanced molecular separation because of their unique transport properties and ability to mimic biological protein channels. In this work the synthetic approach for fabrication of carbon nanotubes (CNTs) composite membranes is presented. The method is based on growth of multi walled carbon nanotubes (MWCNT) using chemical vapour deposition (CVD) on the template of nanoporous alumina (PA) membranes. The influence of experimental conditions including carbon precursor, temperature, deposition time, and PA template on CNT growth process and quality of fabricated membranes was investigated. The synthesis of CNT/PA composites with controllable nanotube dimensions such as diameters (30-150 nm), and thickness (5-100 µm), was demonstrated. The chemical composition and morphological characteristics of fabricated CNT/PA composite membranes were investigated by various characterisation techniques including scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDXS), high resolution transmission electron microscopy (HRTEM) and x-ray diffraction (XRD). Transport properties of prepared membranes were explored by diffusion of dye (Rose Bengal) used as model of hydrophilic transport molecule. PMID:24957494

Altalhi, Tariq; Ginic-Markovic, Milena; Han, Ninghui; Clarke, Stephen; Losic, Dusan

2010-01-01

291

Anticorrosive conductive polyurethane multiwalled carbon nanotube nanocomposites  

E-print Network

Anticorrosive conductive polyurethane multiwalled carbon nanotube nanocomposites Huige Wei,ab Daowei Ding,a Suying Wei*ab and Zhanhu Guo*a Conductive polyurethane (PU) nanocomposite coatings filled that the polyurethane matrix combined with the well dispersed MWNT reinforcements provided a significant physical

Guo, John Zhanhu

292

High Performance Electrolyte Gated Carbon Nanotube Transistors  

E-print Network

High Performance Electrolyte Gated Carbon Nanotube Transistors Sami Rosenblatt, Yuval Yaish to grow the tubes, annealing to improve the contacts, and an electrolyte as a gate, we obtain very high electrodes. The tube diameter is 1.9 nm. (c) Schematic of the electrolyte gate measurement. A water gate

Gore, Jeff

293

High Performance Electrolyte Gated Carbon Nanotube Transistors  

Microsoft Academic Search

We have fabricated high performance field-effect transistors made from semiconducting single-walled carbon nanotubes (SWNTs). Using chemical vapor deposition to grow the tubes, annealing to improve the contacts, and an electrolyte as a gate, we obtain very high device mobilites and transconductances. These measurements demonstrate that SWNTs are attractive for both electronic applications and for chemical and biological sensing.

Sami Rosenblatt; Yuval Yaish; Jiwoong Park; Jeff Gore; Vera Sazonova; Paul L. McEuen

2002-01-01

294

Dispersion of Carbon Nanotubes in Liquids  

Microsoft Academic Search

Production processes for carbon nanotubes often produce mixtures of solid morphologies that are mechanically entangled or that self?associate into aggregates. Entangled or aggregated nanoparticles often need to be dispersed into fluid suspensions in order to develop materials that have unique mechanical characteristics or transport properties. This paper reviews the effects of milling, ultrasonication, high shear flow, elongational flow, functionalization, and

Jenny Hilding; Eric A. Grulke; Z. George Zhang; Fran Lockwood

2003-01-01

295

GAS SENSOR APPLICATION OF CARBON NANOTUBES  

Microsoft Academic Search

Gas sensors have a wide application in everyday life, whether in industry, medical, agriculture and environmental monitoring. A good sensor should be selective, sensitive, responsive, reliable and cost effective. Currently available gas sensors are lacking in one or more of these criteria. Therefore, there is a need to develop new sensing materials and technologies. Carbon nanotubes (CNTs) have the potential

M. Y. Faizah; A. Fakhru' l-Razi; R. M. Sidek; A. G. Liew Abdullah

2007-01-01

296

High-damping carbon nanotube hinged micromirrors.  

PubMed

New developments in digital mirror devices (DMDs) require suspension hinges with a good damping and high temperature stability. Carbon nanotubes (CNTs) offer these unique properties. Herein it is shown how CNT hinges can be integrated in micromirrors. The image illustrates a micromirror with a CNT suspension, and a typical overdamped stepresponse (Q-factor < 0.5). PMID:22511407

De Volder, Michaël F L; De Coster, Jeroen; Reynaerts, Dominiek; Van Hoof, Chris; Kim, Sang-Gook

2012-07-01

297

Carbon nanotubes as supports for inulinase immobilization.  

PubMed

The commercial inulinase obtained from Aspergillus niger was non-covalently immobilized on multiwalled carbon nanotubes (MWNT-COOH). The immobilization conditions for the carbon nanotubes were defined by the central composite rotational design (CCRD). The effects of enzyme concentration (0.8%-1.7% v/v) and adsorbent:adsorbate ratio (1:460-1:175) on the enzyme immobilization were studied. The adsorbent:adsorbate ratio variable has positive effect and the enzyme concentration has a negative effect on the inulinase immobilization (U/g) response at the 90% significance level. These results show that the lower the enzyme concentration and the higher the adsorbent:adsorbate ratio, better is the immobilization. According to the results, it is possible to observe that the carbon nanotubes present an effective inulinase adsorption. Fast adsorption in about six minutes and a loading capacity of 51,047 U/g support using a 1.3% (v/v) inulinase concentration and a 1:460 adsorbent:adsorbate ratio was observed. The effects of temperature on the immobilized enzyme activity were evaluated, showing better activity at 50 °C. The immobilized enzyme maintained 100% of its activity during five weeks at room temperature. The immobilization strategy with MWNT-COOH was defined by the experimental design, showing that inulinase immobilization is a promising biotechnological application of carbon nanotubes. PMID:25225722

Garlet, Tais B; Weber, Caroline T; Klaic, Rodrigo; Foletto, Edson L; Jahn, Sergio L; Mazutti, Marcio A; Kuhn, Raquel C

2014-01-01

298

Single-walled carbon nanotube electronics  

Microsoft Academic Search

Single-walled carbon nanotubes (SWNTs) have emerged as a very promising new class of electronic materials. The fabrication and electronic properties of devices based on individual SWNTs are reviewed. Both metallic and semiconducting SWNTs are found to possess electrical characteristics that compare favorably to the best electronic materials available. Manufacturability issues, however, remain a major challenge

Paul L. McEuen; Michael S. Fuhrer; Hongkun Park

2002-01-01

299

Single molecule fluorescence microscopy of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Single molecule microscopy has been extensively used in the past decade to study individual biomolecules with excellent spatial and temporal resolution. Meanwhile, characterization of nanomaterials and their development towards a variety of biological applications has progressed rapidly. Despite the comparable size of nanoparticles and biomolecules, no microscopy platform and technique currently exists to study the interactions of single biomolecules with nanoparticles. Here, we have successfully developed a set of experimental tools to study the interactions of DNA and proteins on a nanomaterial surface. We observe nucleic acid-encapsulated carbon nanotubes by using fluorophore-labeled complementary DNA to explore the sequence;-specific affinity of DNA to the nano-surface. Our results demonstrate cooperative exfoliation of the oligonucleotides from the nanomaterial surface and sequence-dependent bioavailability of nanotube;-adsorbed DNA for hybridization. The platform is employed in conjunction with a super resolution algorithm to pinpoint sites of DNA hybridization along the length of the nanotube. The ability of a microfluidic channel to easily exchange solution is used to study specific and non;-specific nuclease activity on nanotube;-adsorbed DNA. Protein function is mapped to local DNA topology on the nanomaterial and distance-dependent arrest of protein activity is observed, resulting in a nanotube;-induced arrest of 60% protein activity within 1 nm from the nanoparticle. Accessibility of different points of contact between the DNA and nanotube are assayed for nuclease resistance and range from 5% to 50%.

Jena, Prakrit Vaibhav

300

Energy Carrier Transport In Surface-Modified Carbon Nanotubes  

E-print Network

of organic molecules or inorganic nanoparticles, debundling of nanotubes by dispersing agents, and microwave irradiation. Because carbon nanotubes have unique carrier transport characteristics along a sheet of graphite in a cylindrical shape, the properties...

Ryu, Yeontack

2012-11-30

301

A Continuum Model for Carbon Nanotube-Infused Polyimides  

E-print Network

A Continuum Model for Carbon Nanotube-Infused Polyimides Heather Wilson1 , Sumanth Banda2 , Ralph C, the materials need to withstand this process. The nanotube-infused polyimides are flexible enough to withstand

302

Strain sensing of carbon nanotubes: Numerical analysis of the vibrational frequency of deformed single-wall carbon nanotubes  

Microsoft Academic Search

The potential applications as nanostrain sensors and tunable frequency oscillators make it important to analyze the natural vibrational frequency of deformed carbon nanotubes. We perform extensive molecular-dynamics and continuum analyses to explore the effects of several basic deformation modes (axial tension and compression, bending, torsion) on the vibrational characteristics of single-walled carbon nanotubes. The effects of nanotube length and chirality

Guoxin Cao; Xi Chen; Jeffrey W. Kysar

2005-01-01

303

Hysteresis modeling in ballistic carbon nanotube field-effect transistors  

PubMed Central

Theoretical models are adapted to describe the hysteresis effects seen in the electrical characteristics of carbon nanotube field-effect transistors. The ballistic transport model describes the contributions of conduction energy sub-bands over carbon nanotube field-effect transistor drain current as a function of drain-source and gate-source voltages as well as other physical parameters of the device. The limiting-loop proximity model, originally developed to understand magnetic hysteresis, is also utilized in this work. The curves obtained from our developed model corroborate well with the experimentally derived hysteretic behavior of the transistors. Modeling the hysteresis behavior will enable designers to reliably use these effects in both analog and memory applications. PMID:25187698

Liu, Yian; Moura, Mateus S; Costa, Ademir J; de Almeida, Luiz Alberto L; Paranjape, Makarand; Fontana, Marcio

2014-01-01

304

Purification Procedures for Single-Wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

This report summarizes the comparison of a variety of procedures used to purify carbon nanotubes. Carbon nanotube material is produced by the arc process and laser oven process. Most of the procedures are tested using laser-grown, single-wall nanotube (SWNT) material. The material is characterized at each step of the purification procedures by using different techniques including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), Raman, X-ray diffractometry (XRD), thermogravimetric analysis (TGA), nuclear magnetic resonance (NMR), and high-performance liquid chromatography (HPLC). The identified impurities are amorphous and graphitic carbon, catalyst particle aggregates, fullerenes, and hydrocarbons. Solvent extraction and low-temperature annealing are used to reduce the amount of volatile hydrocarbons and dissolve fullerenes. Metal catalysts and amorphous as well as graphitic carbon are oxidized by reflux in acids including HCl, HNO3 and HF and other oxidizers such as H2O2. High-temperature annealing in vacuum and in inert atmosphere helps to improve the quality of SWNTs by increasing crystallinity and reducing intercalation.

Gorelik, Olga P.; Nikolaev, Pavel; Arepalli, Sivaram

2001-01-01

305

Carbon nanotubes on a spider silk scaffold.  

PubMed

Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations. PMID:24022336

Steven, Eden; Saleh, Wasan R; Lebedev, Victor; Acquah, Steve F A; Laukhin, Vladimir; Alamo, Rufina G; Brooks, James S

2013-01-01

306

Carbon nanotubes on a spider silk scaffold  

NASA Astrophysics Data System (ADS)

Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations.

Steven, Eden; Saleh, Wasan R.; Lebedev, Victor; Acquah, Steve F. A.; Laukhin, Vladimir; Alamo, Rufina G.; Brooks, James S.

2013-09-01

307

Field emission of aligned grown carbon nanotubes  

NASA Astrophysics Data System (ADS)

Tungsten carbide/cobalt hard metals were coated with multi-walled carbon nanotubes (CNT) using microwave assisted chemical vapor deposition (MWCVD). The aspect ratio of the tubes and their packing density were changed by the deposition conditions and by wet-chemical pre-treatments of the substrate surfaces. The influence of the morphology of the nanotube layers on the electron field emission was investigated. The best layers yielded field enhancement factors of 1500 - 2000 and current densities up to 0.1 A/cm2.

Bartsch, Karl; Leonhardt, A.

2003-10-01

308

Molecular ionization from carbon nanotube paper.  

PubMed

Ambient ionization is achieved by spraying from a carbon nanotube (CNT)-impregnated paper surface under the influence of small voltages (?3?V). Organic molecules give simple high-quality mass spectra without fragmentation in the positive or negative ion modes. Conventional field ionization is ruled out, and it appears that field emission of microdroplets occurs. Microscopic examination of the CNT paper confirms that the nanoscale features at the paper surface are responsible for the high electric fields. Raman spectra imply substantial current flows in the nanotubes. The performance of this analytical method was demonstrated for a range of volatile and nonvolatile compounds and a variety of matrices. PMID:24643979

Narayanan, Rahul; Sarkar, Depanjan; Cooks, R Graham; Pradeep, Thalappil

2014-06-01

309

Carbon nanotubes on a spider silk scaffold  

PubMed Central

Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations. PMID:24022336

Steven, Eden; Saleh, Wasan R.; Lebedev, Victor; Acquah, Steve F. A.; Laukhin, Vladimir; Alamo, Rufina G.; Brooks, James S.

2013-01-01

310

Useful vacancies in Single Wall Carbon Nanotubes  

E-print Network

The electronic and structural properties of zigzag and armchair single-wall carbon nanotubes (SWCNT) with a single vacancy or two vacancies located at various distances have been obtained within the frame of the Density Function Theory (DFT) and a Molecular Dynamics method. It is found that the vacancy defects interact at long ranges in armchair SWCNTs unlike the short-range interaction in zigzag SWCNTs. The density of states for different vacancy densities shows that the local energy gap shrinks with the vacancy density increase. This and other results of the investigation provide insight into understanding the relation between the local deformation of a defective nanotube and its measurable electronic properties.

Proykova, A; Li, Feng Yin

2008-01-01

311

Carbon nanotubes degraded by neutrophil myeloperoxidase induce less pulmonary inflammation  

NASA Astrophysics Data System (ADS)

We have shown previously that single-walled carbon nanotubes can be catalytically biodegraded over several weeks by the plant-derived enzyme, horseradish peroxidase. However, whether peroxidase intermediates generated inside human cells or biofluids are involved in the biodegradation of carbon nanotubes has not been explored. Here, we show that hypochlorite and reactive radical intermediates of the human neutrophil enzyme myeloperoxidase catalyse the biodegradation of single-walled carbon nanotubes in vitro, in neutrophils and to a lesser degree in macrophages. Molecular modelling suggests that interactions of basic amino acids of the enzyme with the carboxyls on the carbon nanotubes position the nanotubes near the catalytic site. Importantly, the biodegraded nanotubes do not generate an inflammatory response when aspirated into the lungs of mice. Our findings suggest that the extent to which carbon nanotubes are biodegraded may be a major determinant of the scale and severity of the associated inflammatory responses in exposed individuals.

Kagan, Valerian E.; Konduru, Nagarjun V.; Feng, Weihong; Allen, Brett L.; Conroy, Jennifer; Volkov, Yuri; Vlasova, Irina I.; Belikova, Natalia A.; Yanamala, Naveena; Kapralov, Alexander; Tyurina, Yulia Y.; Shi, Jingwen; Kisin, Elena R.; Murray, Ashley R.; Franks, Jonathan; Stolz, Donna; Gou, Pingping; Klein-Seetharaman, Judith; Fadeel, Bengt; Star, Alexander; Shvedova, Anna A.

2010-05-01

312

Electrochemical Characterization of Carbon Nanotubes for Fuel Cell MEA's  

NASA Technical Reports Server (NTRS)

Single-walled and multi-walled carbon nanotubes from different sources have been evaluated before and after sonication to identify structural differences and evaluate electrochemical performance. Raman spectral analysis and cyclic voltammetry in situ with QCM were the principle means of evaluating the tubes. The raman data indicates that sonication in toluene modifies the structural properties of the nanotubes. Sonication also affects the electrochemical performance of single-walled nanotubes and the multi-walled tubes differently. The characterization of different types of carbon nanotubes leads up to identifying a potential candidate for incorporating carbon nanotubes for fuel cell MEA structures.

Panagaris, Jael; Loyselle, Patricia

2004-01-01

313

Adsorption of Gases on Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

This research focus in studying the interaction between various classical and quantum gases with novel carbon nanostructures, mainly carbon nanotubes (CNTs). Since their discovery by the Japanese physicist Sumio Iijima [1] carbon nanotubes have, experimentally and theoretically, been subjected to many scientific investigation. Studies of adsorption on CNTs are particularly directed toward their better usage in gas storage, gas separation, catalyst, drug delivery, and water purification. We explore the adsorption of different gases entrapped in a single, double, or multi-bundles of CNTs using computer simulations. The first system we investigate consists of Ar and Kr films adsorbed on zigzag or armchair nanotubes. Our simulations revealed that Kr atoms on intermediate size zigzag NTs undergo two phase transitions: A liquid-vapor (L?V), and liquid-commensurate (L?CS) with a fractional coverage of one Kr atoms adsorbed for every four carbon atoms. For Ar on zigzag and armchair NTs, the only transition observed is a L?V. In the second problem, we explore the adsorption of CO2 molecules in a nanotube bundle and calculate the isosteric heat of adsorption of the entrapped molecules within the groove. We observed that the lower the temperature, the higher the isosteric of adsorption. Last, we investigate the adsorption of hydrogen, Helium, and Neon gases on the groove site of two parallel nanotubes. At low temperature, the transverse motion on the plane perpendicular to the tubes' axis is frozen out and as a consequence, the heat capacity is reduced to 1/2. At high temperature, the atoms gain more degree of freedom and as a consequence the heat capacity is 5/2.

Mbaye, Mamadou Thiao

314

Diffusion through Carbon Nanotube Semipermeable membranes  

SciTech Connect

The goal of this project is to measure transport through CNTs and study effects of confinement at molecular scale. This work is motivated by several simulation papers in high profile journals that predict significantly higher transport rates of gases and liquids through carbon nanotubes as compared with similarly-sized nanomaterials (e.g. zeolites). The predictions are based on the effects of confinement, atomically smooth pore walls and high pore density. Our work will provide the first measurements that would compare to and hopefully validate the simulations. Gas flux is predicted to be >1000X greater for SWNTs versus zeolitesi. A high flux of 6-30 H2O/NT/ns {approx} 8-40 L/min for a 1cm{sup 2} membrane is also predicted. Neutron diffraction measurements indicate existence of a 1D water chain within a cylindrical ice sheet inside carbon nanotubes, which is consistent with the predictions of the simulation. The enabling experimental platform that we are developing is a semipermeable membrane made out of vertically aligned carbon nanotubes with gaps between nanotubes filled so that the transport occurs through the nanotubes. The major challenges of this project included: (1) Growth of CNTs in the suitable vertically aligned configuration, especially the single wall carbon nanotubes; (2) Development of a process for void-free filling gaps between CNTs; and (3) Design of the experiments that will probe the small amounts of analyte that go through. Knowledge of the behavior of water upon nanometer-scale confinement is key to understanding many biological processes. For example, the protein folding process is believed to involve water confined in a hydrophobic environment. In transmembrane proteins such as aquaporins, water transport occurs under similar conditions. And in fields as far removed as oil recovery and catalysis, an understanding of the nanoscale molecular transport occurring within the nanomaterials used (e.g. zeolites) is the key to process optimization. Furthermore, advancement of many emerging nanotechnologies in chemistry and biology will undoubtedly be aided by an understanding confined water transport, particularly the details of hydrogen bonding and solvation that become crucial on this length scale. We can envision several practical applications for our devices, including desalination, gas separations, dialysis, and semipermeable fabrics for protection against CW agents etc. The single wall carbon nanotube membranes will be the key platform for applications because they will allow high transport rates of small molecules such as water and eliminate solvated ions or CW agents.

Bakajin, O

2006-02-13

315

Doping single-walled carbon nanotubes with surfactant peptides containing electron-donor substituents  

E-print Network

Doping single-walled carbon nanotubes with surfactant peptides containing electron of single-walled carbon nanotubes (SWCNTs) in nanoelectronics has created much interest as these materials possess remarkable intrinsic electronic properties. For exam- ple, carbon nanotubes permit ballistic

Nielsen, Steven O.

316

Electrochemically Functionalized Single-Walled Carbon Nanotube Ting Zhang,a  

E-print Network

Full Paper Electrochemically Functionalized Single-Walled Carbon Nanotube Gas Sensor Ting Zhang using single-walled carbon nanotubes (SWNT) electrochemically functionalized with polyaniline (PANI sensitivity, detection limit, and reproducibility. Keywords: Single-walled carbon nanotubes, Conducting

317

Synthesis of Carbon Nanotubes Using Sol Gel Route  

NASA Astrophysics Data System (ADS)

Since 1990, carbon nanotubes were discovered and they have been the object of intense scientific study ever since. A carbon nanotube is a honeycomb lattice rolled into a cylinder. The diameter of a carbon nanotube is of nanometer size and the length is in the range of micrometer. Many of the extraordinary properties attributed to nanotubes, such as tensile strength and thermal stability, have inspired predictions of microscopic robots, dent-resistant car bodies and earthquake-resistant buildings. The first products to use nanotubes were electrical. Some General Motors cars already include plastic parts to which nanotubes were added; such plastic can be electrified during painting so that the paint will stick more readily. Two nanotube-based lighting and display products are well on their way to market. In the long term, perhaps the most valuable applications will take further advantage of nanotubes' unique electronic properties. Carbon nanotubes can in principle play the same role as silicon does in electronic circuits, but at a molecular scale where silicon and other standard semiconductors cease to work. There are several routes to synthesize carbon nanotubes; laser vaporization, carbon arc and vapor growth. We have applied a different route using sol gel chemistry to obtain carbon nanotubes. This work is patent-pending.

Abdel-Fattah, Tarek

2002-12-01

318

Carbon Nanotubes: Measuring Dispersion and Length  

SciTech Connect

Advanced technological uses of single-wall carbon nanotubes (SWCNTs) rely on the production of single length and chirality populations that are currently only available through liquid phase post processing. The foundation of all of these processing steps is the attainment of individualized nanotube dispersion in solution; an understanding of the collodial properties of the dispersed SWCNTs can then be used to designed appropriate conditions for separations. In many instances nanotube size, particularly length, is especially active in determining the achievable properties from a given population, and thus there is a critical need for measurement technologies for both length distribution and effective separation techniques. In this Progress Report, we document the current state of the art for measuring dispersion and length populations, including separations, and use examples to demonstrate the desirability of addressing these parameters.

Fagan, Jeffrey A.; Bauer, Barry J.; Hobbie, Erik K.; Becker, Matthew L.; Hight-Walker, Angela; Simpson, Jeffrey R.; Chun, Jaehun; Obrzut, Jan; Bajpai, Vardhan; Phelan, Fred R.; Simien, Daneesh; Yeon Huh, Ji; Migler, Kalman B.

2011-03-01

319

Carbon nanotube photo-thermo-mechanical actuator.  

PubMed

Carbon nanotubes show a remarkable tendency for direct (rapid) temperature increase of the order of hundreds of degrees when exposed to near infra-red light. The reason is local confinement of the heat wave in their 1D structure which generates rapid temperature rise. Here we demonstrate that these high temperatures can be exploited to generate large deformation and force output by anchoring the nanotubes to a substrate. We report energy density (i.e., work done per unit mass) of the nanotube actuator as approximately 4268 J/Kg which is significantly larger than piezoceramic (approximately 4.25 J/Kg), magnetostrictive (approximately 21.6 J/Kg), lead-zinc-niobate/lead-titanate single-crystals (approximately 131 J/Kg), polyvinylidene fluoride trifluoro-ethylene copolymers (approximately 160 J/Kg) and shape memory alloys (approximately 1337 J/Kg). PMID:21456122

Nagar, Rupali; Teki, Ranganath; Srivastava, Iti; Singh, Jitendra P; Koratkar, Nikhil

2011-02-01

320

Spin-based Optomechanics with Carbon Nanotubes  

PubMed Central

A simple scheme for determination of spin-orbit coupling strength in spinbased optomechanics with carbon nanotubes is introduced, under the control of a strong pump field and a weak signal field. The physical mechanism comes from the phonon induced transparency (PIT), by relying on the coherent coupling of electron spin to vibrational motion of the nanotube, which is analogous to electromagnetically induced transparency (EIT) effect in atom systems. Based on this spin-nanotube optomechanical system, we also conceptually design a single photon router and a quantum microwave transistor, with ultralow pump power (~ pW) and tunable switching time, which should provide a unique platform for the study of spin-based microwave quantum optics and quantum information processing. PMID:23198093

Li, Jin-Jin; Zhu, Ka-Di

2012-01-01

321

Synthesis of vertically aligned carbon nanotubes on carbon fiber  

NASA Astrophysics Data System (ADS)

In spite of several researches to synthesize carbon nanotubes (CNTs) on carbon fiber (CF), most have obtained entangled nanotubes versus the aligned form. In this study, by controlling catalyst coating technique, vertically aligned CNT were grown on CF through chemical vapor deposition (CVD). Activated fiber surface originated from acid treatment, compact coverage of catalyst precursor via applying ultrasonication in appropriate solvent, followed by calcinating were effective parameters which resulted in growing bundles and vertically aligned CNT on CF. Ethanol and acetone were examined as solvent thereby spot catalyst coating was created from the former while film coverage produced from the later and resulted in distinctive CNT morphology.

Rahmanian, S.; Suraya, A. R.; Zahari, R.; Zainudin, E. S.

2013-04-01

322

Use of Functionalized Carbon Nanotubes for Covalent Attachment of Nanotubes to Silicon  

NASA Technical Reports Server (NTRS)

The purpose of the invention is to covalently attach functionalized carbon nanotubes to silicon. This step allows for the introduction of carbon nanotubes onto all manner of silicon surfaces, and thereby introduction of carbon nano - tubes covalently into silicon-based devices, onto silicon particles, and onto silicon surfaces. Single-walled carbon nanotubes (SWNTs) dispersed as individuals in surfactant were functionalized. The nano - tube was first treated with 4-t-butylbenzenediazonium tetrafluoroborate to give increased solubility to the carbon nanotube; the second group attached to the sidewall of the nanotube has a silyl-protected terminal alkyne that is de-protected in situ. This gives a soluble carbon nanotube that has functional groups appended to the sidewall that can be attached covalently to silicon. This reaction was monitored by UV/vis/NJR to assure direct covalent functionalization.

Tour, James M.; Dyke, Christopher A.; Maya, Francisco; Stewart, Michael P.; Chen, Bo; Flatt, Austen K.

2012-01-01

323

Magnetic single-walled carbon nanotubes as efficient drug delivery nanocarriers in breast cancer murine model: noninvasive monitoring using diffusion-weighted magnetic resonance imaging as sensitive imaging biomarker  

PubMed Central

Purpose Targeting doxorubicin (DOX) by means of single-walled carbon nanotube (SWCNT) nanocarriers may help improve the clinical utility of this highly active therapeutic agent. Active targeting of SWCNTs using tumor-specific antibody and magnetic attraction by tagging the nanotubes with iron oxide nanoparticles can potentially reduce the unnecessary side effects and provide enhanced theranostics. In the current study, the in vitro and in vivo efficacy of DOX-loaded SWCNTs as theranostic nanoprobes was evaluated in a murine breast cancer model. Methods Iron-tagged SWCNTs conjugated with Endoglin/CD105 antibody with or without DOX were synthetized and extensively characterized. Their biocompatibility was assessed in vitro in luciferase (Luc2)-expressing 4T1 (4T1-Luc2) murine breast cancer cells using TiterTACS™ Colorimetric Apoptosis Detection Kit (apoptosis induction), poly (ADP-ribose) polymerase (marker for DNA damage), and thiobarbituric acid-reactive substances (oxidative stress generation) assays, and the efficacy of DOX-loaded SWCNTs was evaluated by measuring the radiance efficiency using bioluminescence imaging (BLI). Tumor progression and growth were monitored after 4T1-Luc2 cells inoculation using noninvasive BLI and magnetic resonance imaging (MRI) before and after subsequent injection of SWCNT complexes actively and magnetically targeted to tumor sites. Results Significant increases in apoptosis, DNA damage, and oxidative stress were induced by DOX-loaded SWCNTs. In addition, a tremendous decrease in bioluminescence was observed in a dose- and time-dependent manner. Noninvasive BLI and MRI revealed successful tumor growth and subsequent attenuation along with metastasis inhibition following DOX-loaded SWCNTs injection. Magnetic tagging of SWCNTs was found to produce significant discrepancies in apparent diffusion coefficient values providing a higher contrast to detect treatment-induced variations as noninvasive imaging biomarker. In addition, it allowed their sensitive noninvasive diagnosis using susceptibility-weighted MRI and their magnetic targeting using an externally applied magnet. Conclusion Enhanced therapeutic efficacy of DOX delivered through antibody-conjugated magnetic SWCNTs was achieved. Further, the superiority of apparent diffusion coefficient measurements using diffusion-weighted MRI was found to be a sensitive imaging biomarker for assessment of treatment-induced changes. PMID:25565811

Al Faraj, Achraf; Shaik, Abjal Pasha; Shaik, Asma Sultana

2015-01-01

324

Coupling of Carbon Nanotubes to Metallic Contacts  

NASA Technical Reports Server (NTRS)

The modeling of carbon nanotube-metal contacts is important from both basic and applied view points. For many applications, it is important to design contacts such that the transmission is dictated by intrinsic properties of the nanotube rather than by details of the contact. In this paper, we calculate the electron transmission probability from a nanotube to a free electron metal, which is side-contacted. If the metal-nanotube interface is sufficiently ordered, we find that k-vector conservation plays an important role in determining the coupling, with the physics depending on the area of contact, tube diameter, and chirality. The main results of this paper are: (1) conductance scales with contact length, a phenomena that has been observed in experiments and (2) in the case of uniform coupling between metal and nanotube, the threshold value of the metal Fermi wave vector (below which coupling is insignificant) depends on chirality. Disorder and small phase coherence length relax the need for k-vector conservation, thereby making the coupling stronger.

Anantram, M. P.; Datta, S.; Xue, Yong-Xiang; Govindan, T. R. (Technical Monitor)

1999-01-01

325

A Structural Transition of Carbon Nanotubes?  

NASA Technical Reports Server (NTRS)

The superior properties of carbon nanotubes (CNT) are good for many applications. A possible temperature-related structural transition is found in the CNT, which may suggest new applications of CNT. CNT materials have been synthesized on Si substrates by pulsed laser vaporization in various temperatures and pressures. Raman spectroscopy and scanning electron microscopy are used to determine the CNT structure and morphology. It is found that the formation of nanotubes depends strongly on the growth temperatures and high quality multi-wall and single-wall nanotubes were produced at 700 and 990 C, respectively. The radial breath modes of Raman spectra measured in the range of 50 cm(exp -1) to 300 cm(exp -1), indicate that one of samples grown at 700 C is to be dependent on the excitation intensity. The spectra of the sample suggest that the structure is similar to that of multi-wall nanotubes at low excitation intensity (2.5 kW per square centimeter) and it converts to the structure of single-wall nanotubes at higher intensity (25 kW per square centimeter). Measurements taken while cycling the light intensity suggests a reversible transition.

Zhu, Shen; Su, Ching-Hua; Cochrane, J. C.; Lehoczky, S.; Cui, Y.; Burger, A.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

326

Carbon nanotube formation by laser direct writing  

SciTech Connect

This letter presents carbon nanotube (CNT) formation by laser direct writing using 248 nm KrF excimer pulsed laser in air at room temperature, which was applied to irradiate amorphous carbon (a-C) assisted by Ni catalysts underneath for the transformation of carbon species into CNTs. The CNTs were synthesized under appropriate combination of laser energy density and a-C thickness. The growth mechanism and key parameters to determine the success of CNT formation were also discussed. The demonstration of the CNT growth by laser direct writing in air at room temperature opens an opportunity of in-position CNT formation at low temperatures.

Wu, Y.-T.; Su, H.-C.; Tsai, C.-M.; Liu, K.-L.; Chen, G.-D.; Huang, R.-H.; Yew, T.-R. [Department of Materials Science and Engineering, National Tsing-Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan (China)

2008-07-14

327

Carbon nanotube based stationary phases for microchip chromatography.  

PubMed

The objective of this article is to provide an overview and critical evaluation of the use of carbon nanotubes and related carbon-based nanomaterials for microchip chromatography. The unique properties of carbon nanotubes, such as a very high surface area and intriguing adsorptive behaviour, have already been demonstrated in more classical formats, for improved separation performance in gas and liquid chromatography, and for unique applications in solid phase extraction. Carbon nanotubes are now also entering the field of microfluidics, where there is a large potential to be able to provide integrated, tailor-made nanotube columns by means of catalytic growth of the nanotubes inside the fluidic channels. An evaluation of the different implementations of carbon nanotubes and related carbon-based nanomaterials for microfluidic chromatography devices is given in terms of separation performance and ease of fabrication. PMID:22566131

Mogensen, Klaus B; Kutter, Jörg P

2012-05-01

328

Spectroscopic analysis of single-wall carbon nanotubes and carbon nanotube peapods  

Microsoft Academic Search

Raman spectra have been demonstrated repeatedly to be a very valuable tool for the analysis of new carbon phases such as fullerenes and single wall carbon nanotubes (SWCNTs). Recently it was demonstrated from TEM analysis that C60 can be encapsulated into SWCNTs. The structures have been given the name ‘peapods’. The concentration of the encapsulated ‘peas’ and the bonding structure

R. Pfeiffer; H. Kuzmany; W. Plank; T. Pichler; H. Kataura; Y. Achiba

2002-01-01

329

Pentaheptide Alotropes Of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Stone-Wales bond rotation transforms four adjacent graphene hexagons into a pentaheptide ornament consisting of two pentagons and two heptagons. There are two types of lattices of these ornaments, one hexagonal and the other one rectangular. We determine symmetry of arbitrary rolled up nanotubes of both types. This is used to relax the purely folded configurations for large number of tubes, and compare thei stability and electronic properties to the properties of the generic graphene single-wall nanotubes. Density functional tight binding calculations are performed by the full-symmetry implemented numerical code POLSym. Generally, pentaheptide tubes are less stable than the generic ones, and vast majority of them is conducting. For the particular tubes we predict transition from generic to the pentaheptide form by applying mechanical stress.

Damnjanovi?, M.; Volonakis, G.; Logothetidis, S.; Popovi?, Z.; Miloševi?, I.

2007-04-01

330

Process for derivatizing carbon nanotubes with diazonium species  

NASA Technical Reports Server (NTRS)

The invention incorporates new processes for the chemical modification of carbon nanotubes. Such processes involve the derivatization of multi- and single-wall carbon nanotubes, including small diameter (ca. 0.7 nm) single-wall carbon nanotubes, with diazonium species. The method allows the chemical attachment of a variety of organic compounds to the side and ends of carbon nanotubes. These chemically modified nanotubes have applications in polymer composite materials, molecular electronic applications and sensor devices. The methods of derivatization include electrochemical induced reactions thermally induced reactions (via in-situ generation of diazonium compounds or pre-formed diazonium compounds), and photochemically induced reactions. The derivatization causes significant changes in the spectroscopic properties of the nanotubes. The estimated degree of functionality is ca. 1 out of every 20 to 30 carbons in a nanotube bearing a functionality moiety. Such electrochemical reduction processes can be adapted to apply site-selective chemical functionalization of nanotubes. Moreover, when modified with suitable chemical groups, the derivatized nanotubes are chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as, mechanical strength or electrical conductivity) to the properties of the composite material as a whole. Furthermore, when modified with suitable chemical groups, the groups can be polymerized to form a polymer that includes carbon nanotubes ##STR00001##.

Tour, James M. (Inventor); Bahr, Jeffrey L. (Inventor); Yang, Jiping (Inventor)

2007-01-01

331

Carbon nanotube resonator sensors for remote sensing systems  

Microsoft Academic Search

The paper presents our on-going research on the development of carbon nanotube resonator sensors for chemical and, potentially, biological applications. The sensor transducer mechanism is based on changes of resonant frequency of an electromagnetic resonator coated with carbon nanotubes. We have developed carbon nanotube resonator sensor prototypes and found that the sensor is sensitive to both polar (NH3) and non-polar

A. Pham

2003-01-01

332

Direct imaging of single-walled carbon nanotubes in cells  

Microsoft Academic Search

The development of single-walled carbon nanotubes for various biomedical applications is an area of great promise. However, the contradictory data on the toxic effects of single-walled carbon nanotubes highlight the need for alternative ways to study their uptake and cytotoxic effects in cells. Single-walled carbon nanotubes have been shown to be acutely toxic in a number of types of cells,

Alexandra E. Porter; Mhairi Gass; Karin Muller; Jeremy N. Skepper; Paul A. Midgley; Mark Welland

2007-01-01

333

Carbon Nanotube Synthesis and Organization Ernesto Joselevich1  

E-print Network

Carbon Nanotube Synthesis and Organization Ernesto Joselevich1 , Hongjie Dai2 , Jie Liu3 , Kenji j.liu@duke.edu 4 Research Center for Advanced Carbon Materials, National Institute of Advanced CB2 3QZ, UK ahw1@cam.ac.uk Abstract. The synthesis, sorting and organization of carbon nanotubes

Joselevich, Ernesto

334

Functionalized Few-Walled Carbon Nanotubes for Mechanical  

E-print Network

Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan T o date, carbon nanotubes (CNTsFunctionalized Few-Walled Carbon Nanotubes for Mechanical Reinforcement of Polymeric Composites Ye, many well-known issues4 6 still need to be resolved in order to take the maximum benefits from carbon

Liu, Jie

335

A Carbon Nanotube Cable for a Space Elevator  

ERIC Educational Resources Information Center

In this paper the mechanical properties of carbon nanotubes are discussed in connection with the possibility to use them for the construction of a space elevator. From the fundamental information about the structure of a carbon nanotube and the chemical bond between carbon atoms, Young's modulus and the ultimate tensile strength are…

Bochnícek, Zdenek

2013-01-01

336

Development of Carbon Nanotube-Based Sensors—A Review  

Microsoft Academic Search

Carbon nanotubes (CNTs) have shown great promise as sensing elements in nanoelectromechanical sensors. In this review paper, we discuss the electrical, mechanical, and electromechanical properties of CNTs that are used in such applications. This investigation indicates which nanotube properties should be carefully considered when designing nanotube-based sensors. We then present the primary techniques that have been used for the integration

Benjamin Mahar; Cosmin Laslau; Ronnie Yip; Yu Sun

2007-01-01

337

Probing Electrostatic Potentials in Solution with Carbon Nanotube  

E-print Network

Probing Electrostatic Potentials in Solution with Carbon Nanotube Transistors Lisa Larrimore the electrostatic potential sensed by the nanotube, which in turn shifts the gate-voltage dependence of the nanotube of the electrostatic ( ) and chemical (µi) potentials: Amperometric techniques (i.e., measurements of current) provide

McEuen, Paul L.

338

Progress towards monodisperse single-walled carbon nanotubes  

Microsoft Academic Search

The defining characteristic of a nanomaterial is that its properties vary as a function of its size. This size dependence can be clearly observed in single-walled carbon nanotubes, where changes in structure at the atomic scale can modify the electronic and optical properties of these materials in a discontinuous manner (for example, changing metallic nanotubes to semiconducting nanotubes and vice

Mark C. Hersam

2008-01-01

339

Raman spectroscopy on isolated single wall carbon nanotubes  

Microsoft Academic Search

A review is presented on the resonance Raman spectra from one isolated single wall carbon nanotube. The reasons why it is possible to observe the spectrum from only one nanotube are given and the important structural information that is provided by single nanotube spectroscopy is discussed. Emphasis is given to the new physics revealed by the various phonon features found

M. S. Dresselhaus; G. Dresselhaus; A. Jorio; A. G. Souza Filho; R. Saito

2002-01-01

340

Arrays of carbon nanoscrolls as deep subwavelength magnetic metamaterials  

NASA Astrophysics Data System (ADS)

We demonstrate theoretically that an array of carbon nanoscrolls acts as a hyperbolic magnetic metamaterial in the terahertz regime with genuine subwavelength operation corresponding to a wavelength-to-structure ratio of about 200. Due to the low sheet resistance of graphene, the electromagnetic losses in an array of carbon nanoscrolls are almost negligible, offering a very sharp magnetic resonance of extreme positive and negative values of the effective magnetic permeability. The latter property leads to superior imaging properties for arrays of carbon nanoscrolls which can operate as magnetic endoscopes in the terahertz range where magnetic materials are scarce. Our optical modeling is supplemented with ab initio density functional calculations of the self-winding of a single layer of graphene onto a carbon nanotube so as to form a carbon nanoscroll. The latter process is viewed as a means to realize ordered arrays of carbon nanoscrolls in the laboratory based on arrays of aligned carbon nanotubes which are now routinely fabricated.

Yannopapas, Vassilios; Tzavala, Marilena; Tsetseris, Leonidas

2013-10-01

341

Characterization of composites with aligned carbon nanotubes (CNTs) as reinforcement  

E-print Network

Carbon nanotubes' (CNTs) superlative combination of electrical, thermal, and especially mechanical properties make them ideal candidates for composite reinforcement. Nanocomposites and hybrid composite architectures employing ...

García, Enrique J

2006-01-01

342

Photoexcitation of the triplet exciton in single wall carbon nanotubes  

E-print Network

The carbon nanotube photoexcitation spectrum is dominated by excitonic transitions, rather than interband transitions between continuum states. There are eight distinct excitonic transitions (four singlet and four triplet), ...

Santos, Tiffany S.

343

Finite Element Modelling and Molecular Dynamic Simulations of Carbon nanotubes/ Polymer Composites  

E-print Network

Modeling of single-walled carbon nanotubes, multi-walled nanotubes and nanotube reinforced polymer composites using both the Finite Element method and the Molecular Dynamic simulation technique is presented. Nanotubes subjected to mechanical loading...

Gaddamanugu, Dhatri

2010-07-14

344

Carbon nanotube alignment in a thermosetting resin  

NASA Astrophysics Data System (ADS)

Engineering aspects associated with nanocomposite development involves either their final properties either their processability. Both are affected by the distribution of nanofiller in the matrix, or in other words by its dispersion. Mechanical and rheological properties of nanocomposites are directly affected by the aspect ratio of the nanofiller. A nanofilled thermosetting polymer can be exploited as a matrix for continuous fibers when alignment of a high aspect ratio nanofiller is achieved: in this case a hierarchical composite is obtained. A new approach base in two-step is proposed. First the alignment of carbon nanotubes (CNTs) is achieved in a fiber spinning process where an amorphous thermoplastic polymer filled with carbon nanotubes or graphene stacks is used. Then these fibers are aligned and impregnated with the target thermosetting matrix where they ar soluble. After dissolution the nanofillers remained oriented in the thermosetting matrix.

Lionetto, Francesca; Greco, Antonio; Pisignano, Dario; Maffezzoli, Alfonso

2014-05-01

345

Molecular discriminators using single wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

The interaction between single wall carbon nanotubes (SWNTs) and amphiphilic molecules has been studied in a solid phase. SWNTs are allowed to interact with different amphiphilic probes (e.g. lipids) in a narrow capillary interface. Contact between strong hydrophobic and amphiphilic interfaces leads to a molecular restructuring of the lipids at the interface. The geometry of the diffusion front and the rate and the extent of diffusion of the interface are dependent on the structure of the lipid at the interface. Lecithin having a linear tail showed greater mobility of the interface as compared to a branched tail lipid like dipalmitoyl phosphatidylcholine, indicating the hydrophobic interaction between single wall carbon nanotube core and the hydrophobic tail of the lipid. Solid phase interactions between SWNT and lipids can thus become a very simple but efficient means of discriminating amphiphilic molecules in general and lipids in particular.

Bhattacharyya, Tamoghna; Dasgupta, Anjan Kr; Ranjan Ray, Nihar; Sarkar, Sabyasachi

2012-09-01

346

Microstrain in hydroxyapatite carbon nanotube composites.  

PubMed

Synchrotron radiation diffraction data were collected from hydroxyapatite-carbon nanotube bioceramic composites to determine the crystallite size and to measure changes in non-uniform strain. Estimates of crystallite size and strain were determined by line-profile fitting of discrete peaks and these were compared with a Rietveld whole-pattern analysis. Overall the two analysis methods produced very similar numbers. In the commercial hydroxyapatite material, one reflection in particular, (0 2 3), has higher crystallite size and lower strain values in comparison with laboratory-synthesized material. This could indicate preferential crystal growth in the [0 2 3] direction in the commercial material. From the measured strains in the pure material and the composite, there was a degree of bonding between the matrix and strengthening fibres. However, increasing the amount of carbon nanotubes in the composite has increased the strain in the material, which is undesirable for biomedical implant applications. PMID:18097082

Kealley, Catherine; Elcombe, Margaret; van Riessen, Arie

2008-01-01

347

Carbon Nanotubes as Electrical Interfaces with Neurons  

Microsoft Academic Search

\\u000a Carbon nanotubes (CNTs) are emerging as promising nanomaterials for biomedical applications. Due to their unique structural,\\u000a mechanical and electronic properties, CNTs can be used as electrical interfaces with the brain in particular with neurons.\\u000a CNT-based neural interfaces\\/electrodes have been employed in cell culture and in vivo; they offer advantages over standard\\u000a metal-based electrodes in terms of monitoring and stimulation of

William Lee; Vladimir Parpura

348

Electronic Structures of Selected Carbon Nanotubes  

Microsoft Academic Search

We employed a local density functional potential in the linear combination of Gaussian orbital (LCGO) formulism to perform ab-initio, self-consistent calculations of the electronic structure of selected carbon nanotubes using the Bagayoko, Zhao, and Williams (BZW) procedure. We present electronic energy bands, band gaps, density states, and effective masses for (29,0), (22,0), (17,0), (13,0), (10,0), (8,0), (7,0), (10,5), and (8,4)

D. Bagayoko; G. L. Zhao

2002-01-01

349

Nanotube array controlled carbon plasma deposition  

NASA Astrophysics Data System (ADS)

Finding approaches to control the elementary processes of plasma-solid interactions and direct the fluxes of matter at nano-scales becomes an important aspect in science. This letter reports that, by taking advantages of the spacing characteristics of discrete TiO2 nanotube arrays, the flying trajectories and the subsequent implantation and deposition manner of energetic carbon ions can be directed and controlled to fabricate hollow conical arrays. The study provides an alternative method for plasma nano-manufacturing.

Qian, Shi; Cao, Huiliang; Liu, Xuanyong; Ding, Chuanxian

2013-06-01

350

Conductive carbon nanotubes for semiconductor metrology  

NASA Astrophysics Data System (ADS)

This paper presents an evaluation of e-beam assisted deposition and welding of conductive carbon nanotube (c-CNT) tips for electrical scanning probe microscope measurements. Variations in CNT tip conductivity and contact resistance during fabrication were determined as a function of tip geometry using tunneling AFM (TUNA). Conductive CNT tips were used to measure 2D dopant concentration as a function of annealing conditions in BF2-implanted samples.

Vartanian, Victor; McClure, Paul; Mancevski, Vladimir; Kopanski, Joseph J.; Rack, Philp D.; Sitnitsky, Ilona; Bresin, Matthew D.; LaBella, Vince; Dunn, Kathleen

2010-08-01

351

Identification of Complex Carbon Nanotube Structures  

NASA Technical Reports Server (NTRS)

A variety of complex carbon nanotube (CNT) structures have been observed experimentally. These include sharp bends, branches, tori, and helices. They are believed to be formed by using topological defects such as pentagons and heptagons to connect different CNT. The effects of type, number, and arrangement (separation and orientation) of defects on atomic structures and energetics of complex CNT are investigated using topology, quantum mechanics and molecular mechanics calculations. Energetically stable models are derived for identification of observed complex CNT structures.

Han, Jie; Saini, Subhash (Technical Monitor)

1998-01-01

352

Nanotube array controlled carbon plasma deposition  

SciTech Connect

Finding approaches to control the elementary processes of plasma-solid interactions and direct the fluxes of matter at nano-scales becomes an important aspect in science. This letter reports that, by taking advantages of the spacing characteristics of discrete TiO{sub 2} nanotube arrays, the flying trajectories and the subsequent implantation and deposition manner of energetic carbon ions can be directed and controlled to fabricate hollow conical arrays. The study provides an alternative method for plasma nano-manufacturing.

Qian, Shi; Cao, Huiliang; Liu, Xuanyong; Ding, Chuanxian [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)] [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

2013-06-17

353

An ultrafast carbon nanotube terahertz polarisation modulator  

SciTech Connect

We demonstrate ultrafast modulation of terahertz radiation by unaligned optically pumped single-walled carbon nanotubes. Photoexcitation by an ultrafast optical pump pulse induces transient terahertz absorption in nanowires aligned parallel to the optical pump. By controlling the polarisation of the optical pump, we show that terahertz polarisation and modulation can be tuned, allowing sub-picosecond modulation of terahertz radiation. Such speeds suggest potential for semiconductor nanowire devices in terahertz communication technologies.

Docherty, Callum J.; Stranks, Samuel D.; Habisreutinger, Severin N.; Joyce, Hannah J.; Herz, Laura M.; Nicholas, Robin J.; Johnston, Michael B., E-mail: m.johnston@physics.ox.ac.uk [Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU (United Kingdom)

2014-05-28

354

Carbon nanotube-reinforced polyurethane composite fibers  

Microsoft Academic Search

Multi-walled carbon nanotubes (MWNTs) reinforced polyurethane (PU) composite fibers have been fabricated via a twin-screw extrusion method. Significant improvement in Young’s modulus and tensile strength were achieved by incorporating MWNTs up to 9.3wt% while without sacrificing PU elastomer’s high elongation at break. Electron microscopy was used to investigate dispersion and fracture surfaces, and Raman technique was used to receive information

Wei Chen; Xiaoming Tao; Yuyang Liu

2006-01-01

355

Aqueous solution dispersement of carbon nanotubes  

NASA Technical Reports Server (NTRS)

Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group.

Kim, Jae-Woo (Inventor); Park, Cheol (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

2011-01-01

356

Super-tough carbon-nanotube fibres  

NASA Astrophysics Data System (ADS)

The energy needed to rupture a fibre (its toughness) is five times higher for spider silk than for the same mass of steel wire, which has inspired efforts to produce spider silk commercially. Here we spin 100-metre-long carbon-nanotube composite fibres that are tougher than any natural or synthetic organic fibre described so far, and use these to make fibre supercapacitors that are suitable for weaving into textiles.

Dalton, Alan B.; Collins, Steve; Muñoz, Edgar; Razal, Joselito M.; Ebron, Von Howard; Ferraris, John P.; Coleman, Jonathan N.; Kim, Bog G.; Baughman, Ray H.

2003-06-01

357

Excited State Dynamics in Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotube, one of the most promising materials for nano-technology, still suffers from its imperfection in crystalline structure that will make performance of nanotube behind theoretical limit. From the first-principles simulations, I propose efficient methods to overcome the imperfection. I show that photo-induced ion dynamics can (1) identify defects in nanotubes, (2) stabilize defected nanotubes, and (3) purify contaminated nanotubes. All of these methods can be alternative to conventional heat treatments and will be important techniques for realizing nanotube-devices. Ion dynamics under electronic excitation has been simulated with use of the computer code FPSEID (First-Principles Simulation tool for Electron Ion Dynamics) [1], which combines the time-dependent density functional method [2] to classical molecular dynamics. This very challenging approach is time-consuming but can automatically treat the level alternation of differently occupied states, and can observe initiation of non-adiabatic decay of excitation. The time-dependent Kohn-Sham equation has been solved by using the Suzuki-Trotter split operator method [3], which is a numerically stable method being suitable for plane wave basis, non-local pseudopotentials, and parallel computing. This work has been done in collaboration with Prof. Angel Rubio, Prof. David Tomanek, Dr. Savas Berber and Mina Yoon. Most of present calculations have been done by using the SX5 Vector-Parallel system in the NEC Fuchu-plant, and the Earth Simulator in Yokohama Japan. [1] O. Sugino and Y. Miyamoto, Phys. Rev. B59, 2579 (1999); ibid, B66 089901(E) (2001) [2] E. Runge and E. K. U. Gross, Phys. Rev. Lett. 52, 997 (1984). [3] M. Suzuki, J. Phys. Soc. Jpn. 61, L3015 (1992).

Miyamoto, Yoshiyuki

2004-03-01

358

Exceptionally high Young's modulus observed for individual carbon nanotubes  

NASA Astrophysics Data System (ADS)

CARBON nanotubes are predicted to have interesting mechanical properties-in particular, high stiffness and axial strength-as a result of their seamless cylindrical graphitic structure1-5. Their mechanical properties have so far eluded direct measurement, however, because of the very small dimensions of nanotubes. Here we estimate the Young's modulus of isolated nanotubes by measuring, in the transmission electron microscope, the amplitude of their intrinsic thermal vibrations. We find that carbon nanotubes have exceptionally high Young's moduli, in the terapascal (TPa) range. Their high stiffness, coupled with their low density, implies that nanotubes might be useful as nanoscale fibres in strong, lightweight composite materials.

Treacy, M. M. J.; Ebbesen, T. W.; Gibson, J. M.

1996-06-01

359

Ferroelectric-carbon nanotube memory devices.  

PubMed

One-dimensional ferroelectric nanostructures, carbon nanotubes (CNT) and CNT-inorganic oxides have recently been studied due to their potential applications for microelectronics. Here, we report coating of a registered array of aligned multi-wall carbon nanotubes (MWCNT) grown on silicon substrates by functional ferroelectric Pb(Zr,Ti)O3 (PZT) which produces structures suitable for commercial prototype memories. Microstructural analysis reveals the crystalline nature of PZT with small nanocrystals aligned in different directions. First-order Raman modes of MWCNT and PZT/MWCNT/n-Si show the high structural quality of CNT before and after PZT deposition at elevated temperature. PZT exists mostly in the monoclinic Cc/Cm phase, which is the origin of the high piezoelectric response in the system. Low-loss square piezoelectric hysteresis obtained for the 3D bottom-up structure confirms the switchability of the device. Current-voltage mapping of the device by conducting atomic force microscopy (c-AFM) indicates very low transient current. Fabrication and functional properties of these hybrid ferroelectric-carbon nanotubes is the first step towards miniaturization for future nanotechnology sensors, actuators, transducers and memory devices. PMID:22460805

Kumar, Ashok; Shivareddy, Sai G; Correa, Margarita; Resto, Oscar; Choi, Youngjin; Cole, Matthew T; Katiyar, Ram S; Scott, James F; Amaratunga, Gehan A J; Lu, Haidong; Gruverman, Alexei

2012-04-27

360

Carbon nanotube-doped tellurite glasses  

NASA Astrophysics Data System (ADS)

In the past it was observed that buck ball doped glasses showed enhanced optical nonlinearities. However, carbon nanotubes are much more stable than buck ball and should be a better choice for that purpose. Therefore we decided to investigate the possibility to produce carbon nanotubes doped tellurite glasses and measured their optical nonlinearities. Tellurite glasses already have a larger nonlinearity compared to silica, and other, glasses. We produced TeO II-ZnO tellurite family glasses doped with multi wall Carbon Nanotube (CNT). The CNTs acquired from Carbolex were vigorously mechanically mixed with the tellurite glass precursors and melted in platinum crucible around 650°C in a controlled atmosphere inside an electrical induction furnace. We used the lowest temperature possible and controlled atmosphere to avoid the CNT oxidation. The glass melt was cast in a stainless steel and thermally treated at 300°C for 5 hours to relieve internal stresses. The samples were than cutted and polished to perform the optical characterization. We measured refractive index and thermo physical properties, such as vitreous transition T g, crystallization onset T x and melting T f temperatures. Raman spectroscopy showed the possible presence of CNTs.

Mazali, I. O.; Chillcce, E. F.; Ferreira, O. P.; Rodriguez, E.; Jacob, G. J.; Cesar, C. L.; Barbosa, L. C.

2008-02-01

361

Fast Electromechanical Switches Based on Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

Electrostatically actuated nanoelectromechanical switches based on carbon nanotubes have been fabricated and tested in a continuing effort to develop high-speed switches for a variety of stationary and portable electronic equipment. As explained below, these devices offer advantages over electrostatically actuated microelectromechanical switches, which, heretofore, have represented the state of the art of rapid, highly miniaturized electromechanical switches. Potential applications for these devices include computer memories, cellular telephones, communication networks, scientific instrumentation, and general radiation-hard electronic equipment. A representative device of the present type includes a single-wall carbon nanotube suspended over a trench about 130 nm wide and 20 nm deep in an electrically insulating material. The ends of the carbon nanotube are connected to metal electrodes, denoted the source and drain electrodes. At bottom of the trench is another metal electrode, denoted the pull electrode (see figure). In the off or open switch state, no voltage is applied, and the nanotube remains out of contact with the pull electrode. When a sufficiently large electric potential (switching potential) is applied between the pull electrode and either or both of the source and drain electrodes, the resulting electrostatic attraction bends and stretches the nanotube into contact with the pull electrode, thereby putting the switch into the "on" or "closed" state, in which substantial current (typically as much as hundreds of nanoamperes) is conducted. Devices of this type for use in initial experiments were fabricated on a thermally oxidized Si wafer, onto which Nb was sputter-deposited for use as the pull-electrode layer. Nb was chosen because its refractory nature would enable it to withstand the chemical and thermal conditions to be subsequently imposed for growing carbon nanotubes. A 200- nm-thick layer of SiO2 was formed on top of the Nb layer by plasma-enhanced chemical vapor deposition. In the device regions, the SiO2 layer was patterned to thin it to the 20-nm trench depth. The trenches were then patterned by electron- beam lithography and formed by reactive- ion etching of the pattern through the 20-nm-thick SiO2 to the Nb layer.

Kaul, Anupama; Wong, Eric; Epp, Larry

2008-01-01

362

Reversible separation of single-walled carbon nanotubes in bundles  

SciTech Connect

We show that electrostatic charging of nanotubes and the consequent repulsion can lead to reversible separation of individual single-walled carbon nanotubes in bundles. Low-energy electron beam irradiation leads to this completely reversible phenomenon. A simple semianalytical model is used to explain the observed separation mechanism. The reversibility of the separation process is attributed to discharging and thermal-fluctuation induced motion of the nanotubes in ambient air. Further, the separation impacts the electrical conductance of small nanotube bundled devices.

Sahoo, Sangeeta; Lastella, Sarah [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3590 (United States); Maranganti, Ravi; Sharma, Pradeep [Department of Mechanical Engineering, University of Houston, Houston, Texas 77204 (United States); Mallick, Govind; Karna, Shashi [AMSRD-ARL-WM-BD, Weapons and Materials Directorate, US Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005-5069 (United States); Ajayan, Pulickel M. [Department of Mechanical Engineering and Materials Science, Rice University, 6100 Main Street, Houston, Texas 77005 (United States)

2008-08-25

363

TOPICAL REVIEW: Carbon nanotubes for biological and biomedical applications  

NASA Astrophysics Data System (ADS)

Ever since the discovery of carbon nanotubes, researchers have been exploring their potential in biological and biomedical applications. The recent expansion and availability of chemical modification and bio-functionalization methods have made it possible to generate a new class of bioactive carbon nanotubes which are conjugated with proteins, carbohydrates, or nucleic acids. The modification of a carbon nanotube on a molecular level using biological molecules is essentially an example of the 'bottom-up' fabrication principle of bionanotechnology. The availability of these biomodified carbon nanotube constructs opens up an entire new and exciting research direction in the field of chemical biology, finally aiming to target and to alter the cell's behaviour at the subcellular or molecular level. This review covers the latest advances of bio-functionalized carbon nanotubes with an emphasis on the development of functional biological nano-interfaces. Topics that are discussed herewith include methods for biomodification of carbon nanotubes, the development of hybrid systems of carbon nanotubes and biomolecules for bioelectronics, and carbon nanotubes as transporters for a specific delivery of peptides and/or genetic material to cells. All of these current research topics aim at translating these biotechnology modified nanotubes into potential novel therapeutic approaches.

Yang, Wenrong; Thordarson, Pall; Gooding, J. Justin; Ringer, Simon P.; Braet, Filip

2007-10-01

364

Nanostructuring electrodes with carbon nanotubes: A review on electrochemistry and applications for sensing  

Microsoft Academic Search

Carbon nanotubes have begun to attract enormous interest in electrochemistry because of their small size and good electrochemical properties. The vast majority of studies thus far have used ensembles of carbon nanotubes to nanostructure macroscopic electrodes either with randomly dispersed nanotubes or with aligned carbon nanotubes. The resultant nanotube modified electrodes have most frequently been used for electro-analytical purposes such

J. Justin Gooding

2005-01-01

365

Controlled placement and electrical contact properties of individual multiwalled carbon nanotubes on patterned silicon chips  

NASA Astrophysics Data System (ADS)

A scheme that allows on-chip growth of multiwalled carbon nanotubes at designed locations is demonstrated. The nanotubes were grown by thermal chemical vapor deposition and were contacted to nanoscaled Cr electrodes fabricated by standard e-beam lithography techniques. The contacts were found to be Ohmic with resistance values on the order of 103 ? at room temperature. Remarkably, the contacts showed weak temperature dependence down to 40 mK and were insensitive to the magnetic field up to 5 T.

Hsiou, Y. F.; Yang, Y. J.; Stobinski, L.; Kuo, Watson; Chen, C. D.

2004-02-01

366

Optimized fabrication and characterization of carbon nanotube spin valves  

SciTech Connect

We report an improved fabrication scheme for carbon based nanospintronic devices and demonstrate the necessity for a careful data analysis to investigate the fundamental physical mechanisms leading to magnetoresistance. The processing with a low-density polymer and an optimised recipe allows us to improve the electrical, magnetic, and structural quality of ferromagnetic Permalloy contacts on lateral carbon nanotube (CNT) quantum dot spin valve devices, with comparable results for thermal and sputter deposition of the material. We show that spintronic nanostructures require an extended data analysis, since the magnetization can affect all characteristic parameters of the conductance features and lead to seemingly anomalous spin transport. In addition, we report measurements on CNT quantum dot spin valves that seem not to be compatible with the orthodox theories for spin transport in such structures.

Samm, J.; Gramich, J.; Baumgartner, A., E-mail: andreas.baumgartner@unibas.ch; Weiss, M.; Schönenberger, C. [Institute of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel (Switzerland)

2014-05-07

367

Carbon Nanotube Based Devices for Intracellular Analysis  

NASA Astrophysics Data System (ADS)

Scientific investigations on individual cells have gained increasing attention in recent years as efforts are being made to understand cellular functioning in complex processes, such as cell division during embryonic development, and owing to realization of heterogeneity amongst a population of a single cell type (for instance, certain individual cancer cells being immune to chemotherapy). Therefore devices enabling electrochemical detection, spectroscopy, optical observations, and separation techniques, along with cell piercing and fluid transfer capabilities at the intra-cellular level, are required. Glass pipettes have conventionally been used for single cell interrogation, however their poor mechanical properties and an intrusive conical geometry have led to limited precision and frequent cell damage or death, justifying research efforts to develop novel, non-intrusive cell probes. Carbon nanotubes (CNTs) are known for their superior physical properties and tunable chemical structure. They possess a high aspect ratio and offer minimally invasive thin carbon walls and tubular geometry. Moreover, possibility of chemical functionalization of CNTs enables multi-functional probes. In this dissertation, novel nanofluidic instruments that have nanostructured carbon tips will be presented along with techniques that utilize the exceptional physical properties of carbon nanotubes, to take miniature biomedical instrumentation to the next level. New methods for fabricating the probes were rigorously developed and their operation was extensively studied. The devices were mechanically robust and were used to inject liquids to a single cell, detect electrochemical signals and enable surface enhanced Raman spectroscopy (SERS) while inducing minimal harm to the cell. Particular attention was focused on the CVD process-which was used to deposit carbon, fluid flow through the nanotubes, and separation of chemical species (atto-liter chromatography) at the nanometer scale that would potentially lead to the highly sought after "selective component extraction" and analysis from a single cell. These multi-functional devices therefore provide a picture of the physiological state of a living cell and function as endoscopes for single cell analysis.

Singhal, Riju Mohan

368

Field-Modulated Carrier Transport in Carbon Nanotube Transistors  

Microsoft Academic Search

We have investigated the electrical transport properties of carbon nanotube field-effect transistors as a function of channel length, gate dielectric film thickness, and dielectric material. Our experiments show that the bulk properties of the semiconducting carbon nanotubes do not limit the current flow through the metal\\/nanotube\\/metal system. Instead, our results can be understood in the framework of gate and source-drain

J. Appenzeller; J. Knoch; V. Derycke; R. Martel; S. Wind; Ph. Avouris

2002-01-01

369

Hydrogen evolution on hydrophobic aligned carbon nanotube arrays.  

PubMed

We investigate for the first time hydrophobic carbon nanotube-based electrochemical cells as an alternative solution to hydrogen sorting. We show that the electrically conducting surface of the nanotube arrays can be used as a cathode for hydrogen generation and absorption by electrolyzing water. We support our findings with Raman and gas chromatography measurements. These results suggest that carbon nanotube forests, presenting a unique combination of hydrophobicity and conductivity, are suitable for application in fuel cells and microelectromechanical devices. PMID:19928998

Misra, Abha; Giri, Jyotsnendu; Daraio, Chiara

2009-12-22

370

Stepped carbon nanotubes synthesized in anodic aluminum oxide templates  

Microsoft Academic Search

Anodic aluminum oxide templates with stepped nano channels were fabricated by repeated anodization and pore widening processes, and carbon nanotubes were grown on the templates without catalytic metals by pyrolysis of acetylene. High-resolution transmission electron microscopy revealed that the wall of the CNTs has a multi-wall structure made of stacked graphite flakes of several nm sizes. For the carbon nanotube

W. S. Im; Y. S. Cho; G. S. Choi; F. C. Yu; D. J. Kim

2004-01-01

371

Optical Properties of Aligned Carbon Nanotube Mats for Photonic Applications  

Microsoft Academic Search

We studied the optical properties of the aligned carbon nanotube (16, 0), (10, 0) and (8, 4) mats for photonic device applications. We employed the ab-initio density functional calculations in the linear combination of atomic orbital formalism. We calculated the electronic structure of the carbon nanotube mats and the real and imaginary parts of the dielectric functions as functions of

G. L. Zhao; D. Bagayoko; L. Yang

2006-01-01

372

Optical properties of aligned carbon nanotube mats for photonic applications  

Microsoft Academic Search

We studied the optical properties of the aligned carbon nanotube (16, 0), (10, 0), and (8, 4) mats for photonic device applications. We employed ab initio density functional potentials and utlized the linear combination of atomic orbital formalism. We calculated the electronic structure of the carbon nanotube mats and the real and imaginary parts of the dielectric functions as functions

G. L. Zhao; D. Bagayoko; L. Yang

2006-01-01

373

Design of efficient terahertz antennas: Carbon nanotube versus gold  

Microsoft Academic Search

In this paper, by using scalability of equivalent circuit of single-wall carbon nanotube (SWNT) in its bundle structure, bundled carbon nanotube (CNT) are modeled by the macroscopic resistive sheet. The numerical simulation implements the boundary condition of the surface resistivity. An anisotropic resistive sheet model to represent bundled CNTs electromagnetically is presented. Then, a numerical simulation using method of moments

Sangjo Choi; Kamal Sarabandi

2010-01-01

374

Narrow Carbon Nanotubes: Metals or Semiconductors? I. Cabria,1  

E-print Network

Narrow Carbon Nanotubes: Metals or Semiconductors? I. Cabria,1 J. W. Mintmire,1 and C. T. White2 1, Washington, DC 20375-5320 (Dated: January 27, 2003) We report local density functional results that show in producing carbon nanotubes with diameters smaller than the 0.7 nm diameter of icosahedral (Ih) C60

Mintmire, John W.

375

Polymer Electrolyte Gating of Carbon Nanotube Network Transistors  

E-print Network

Polymer Electrolyte Gating of Carbon Nanotube Network Transistors Taner Ozel,,| Anshu Gaur,,| John Network behavior in single-walled carbon nanotubes (SWNTs) is examined by polymer electrolyte gating. High gate efficiencies, low voltage operation, and the absence of hysteresis in polymer electrolyte gating

Rogers, John A.

376

Absorption spectroscopy of individual single-walled carbon nanotubes  

E-print Network

Absorption spectroscopy of individual single-walled carbon nanotubes Stéphane Berciaud,a Laurent, published in "Nano Letters 7, 5 (2007) 1203-1207" DOI : 10.1021/nl062933k #12;Single-walled carbon nanotubes and Environmental Nanotechnology, Rice University, Houston, TX 77005, USA Current methods for producing single-walled

Boyer, Edmond

377

Anode Sheath Switching in a Carbon Nanotube Arc Plasma  

SciTech Connect

The anode ablation rate is investigated as a function of anode diameter for a carbon nanotube arc plasma. It is found that anomalously high ablation occurs for small anode diameters. This result is explained by the formation of a positive anode sheath. The increased ablation rate due to this positive anode sheath could imply greater production rate for carbon nanotubes.

Abe Fetterman, Yevgeny Raitses, and Michael Keidar

2008-04-08

378

Carbon nanotubes from catalytic pyrolysis of deoiled asphalt  

Microsoft Academic Search

High purity and uniform carbon nanotubes with about 35 nm in diameter were produced by pyrolysis of deoiled asphalt in the presence of ferrocene in an atmosphere of hydrogen and argon at 1000 °C. Characterization of carbon nanotubes was carried out by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray energy dispersive spectroscopy (EDS), Raman spectroscopy and

Xuguang Liu; Yongzhen Yang; Hongyan Liu; Weiyun Ji; Chunyi Zhang; Bingshe Xu

2007-01-01

379

Carbon nanotube plectonemes: Loops of twisted helices  

E-print Network

The relaxation of twist in elastic filaments often drives conformational changes. We explore this paradigm using all-atom computations and report the formation of novel supercoiled shapes in individual carbon nanotubes (CNTs). Decreasing the end distance of torsionally constrained CNTs leads to spontaneous nucleation and growth of a nanotube plectoneme. We develop a stability diagram and comparisons with theoretical frameworks reveal the importance of non-local van Der Waals interactions. In some cases, they stabilize the supercoiling to an extent that its tip locally kinks and then irreversibly reconstructs into a disordered yet strengthened structure that involves $sp^3$ bonding. The ability to engineer supercoiled conformations of CNTs and related nanoscale filaments opens the possibility of a unique set of tunable functional properties at the nanoscale.

Alireza Shahabi; Moneesh Upmanyu

2014-10-27

380

A carbon nanotube immunosensor for Salmonella  

NASA Astrophysics Data System (ADS)

Antibody-functionalized carbon nanotube devices have been suggested for use as bacterial detectors for monitoring of food purity in transit from the farm to the kitchen. Here we report progress towards that goal by demonstrating specific detection of Salmonella in complex nutrient broth solutions using nanotube transistors functionalized with covalently-bound anti-Salmonella antibodies. The small size of the active device region makes them compatible with integration in large-scale arrays. We find that the on-state current of the transistor is sensitive specifically to the Salmonella concentration and saturates at low concentration (<1000 cfu/ml). In contrast, the carrier mobility is affected comparably by Salmonella and other bacteria types, with no sign of saturation even at much larger concentrations (108 cfu/ml).

Lerner, Mitchell B.; Goldsmith, Brett R.; McMillon, Ronald; Dailey, Jennifer; Pillai, Shreekumar; Singh, Shree R.; Johnson, A. T. Charlie

2011-12-01

381

Radial deformation and adhesion of carbon nanotube  

NASA Astrophysics Data System (ADS)

The van der Waals (vdW) interactions of carbon nanotube (CNT)-substrate and CNT-CNT can cause strong adhesion. The adhesion can lead to radial deformation of CNTs, which is shown in both experiments and theoretical analysis. A scaling approach is used to predict the mechanical properties, vdW adhesion, and the elastic deformation of CNTs. It is found that the indentation of CNT is proportional to R 7/4 and h -3/2 in nanotube-substrate system and two same CNT system. Here, R and h are the radius and the wall thickness of CNT, respectively. The indentation ratio H 1/ H 2 for CNT-CNT is proportional to ( R 1/ R 2)3/2 and ( h 2/ h 1)3/2.

Wang, GenWei

2014-08-01

382

Onion-like carbon and carbon nanotube film antennas  

NASA Astrophysics Data System (ADS)

In this paper, radiating dipole antennas have been fabricated from rolled carbon films, which are typically used for supercapacitor electrodes. Return loss and radiation pattern measurements for onion-like carbon (OLC) and multi-walled carbon nanotubes (MWCNTs) antenna samples are presented and compared to a copper standard. The OLC antenna's radiation pattern measurements show a peak gain of -1.48 dBi, just less than 3 dB of a copper dipole antenna. Compared to antennas made from MWCNT films, the OLC samples show better radiation performance despite a lower measured conductivity.

Vacirca, Nicholas A.; McDonough, John K.; Jost, Kristy; Gogotsi, Yury; Kurzweg, Timothy P.

2013-08-01

383

Catalysts for Efficient Production of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

Several metal alloys have shown promise as improved catalysts for catalytic thermal decomposition of hydrocarbon gases to produce carbon nanotubes (CNTs). Heretofore almost every experiment on the production of carbon nanotubes by this method has involved the use of iron, nickel, or cobalt as the catalyst. However, the catalytic-conversion efficiencies of these metals have been observed to be limited. The identification of better catalysts is part of a continuing program to develop means of mass production of high-quality carbon nanotubes at costs lower than those achieved thus far (as much as $100/g for purified multi-wall CNTs or $1,000/g for single-wall CNTs in year 2002). The main effort thus far in this program has been the design and implementation of a process tailored specifically for high-throughput screening of alloys for catalyzing the growth of CNTs. The process includes an integral combination of (1) formulation of libraries of catalysts, (2) synthesis of CNTs from decomposition of ethylene on powders of the alloys in a pyrolytic chemical-vapor-decomposition reactor, and (3) scanning- electron-microscope screening of the CNTs thus synthesized to evaluate the catalytic efficiencies of the alloys. Information gained in this process is put into a database and analyzed to identify promising alloy compositions, which are to be subjected to further evaluation in a subsequent round of testing. Some of these alloys have been found to catalyze the formation of carbon nano tubes from ethylene at temperatures as low as 350 to 400 C. In contrast, the temperatures typically required for prior catalysts range from 550 to 750 C.

Sun, Ted X.; Dong, Yi

2009-01-01

384

Quantum dot manipulation in a single-walled carbon nanotube using a carbon nanotube gate  

Microsoft Academic Search

Cross junctions of carbon nanotubes (CNTs) separated by thin oxide layers have been fabricated, in which the top CNT is used as a local gate to control the electron transport through the lower CNT. Coulomb oscillation was observed in the lower CNTs at low temperatures. The gating field from the upper CNTs is seen to modulate the band structure in

Dong Su Lee; Seung Joo Park; Sang Deok Park; Yung Woo Park; Marianna Kemell; Mikko Ritala; Johannes Svensson; Mats Jonson; Eleanor E. B. Campbell

2006-01-01

385

Gas sensors based on single-wall carbon nanotubes and polypyrrole-coated carbon nanotubes  

Microsoft Academic Search

We have fabricated gas sensors based on single-wall carbon nanotubes and detected NH3 and NO2 gas. At the room temperature, the absorbed gas molecules are not easily detached from the CNT surface. So, we have testes the gas sensor at high temperatures and investigated the temperature dependences of electrical properties of CNTs above the room temperatures. Depending on the gas

Young Wook Chang; Je Seung Oh; Seung Hwan Yoo; Ji Hun Kim; Hyang Hee Choi; Kyung-Hwa Yoo

2007-01-01

386

1% solar cells derived from ultrathin carbon nanotube photoabsorbing films  

NASA Astrophysics Data System (ADS)

Using a carbon nanotube photoabsorbing film <5 nm in thickness, we demonstrate a 1% solar cell. Specifically, polymer wrapped, highly monochiral (7, 5) nanotubes are implemented in a bilayered heterojunction with acceptor C60. The nanotubes drive 63% of the conversion, several times stronger than previously demonstrated. Peak external quantum efficiency (QE) of 43% at the nanotube bandgap (1055 nm) and power conversion efficiency of 0.95% and 1.02% at 1.0 and 1.5 suns, respectively, are achieved. The high internal QE from the ultrathin layers suggests that nanostructured or multijunction cells exploiting multiple nanotube layers will be many times more efficient.

Shea, Matthew J.; Arnold, Michael S.

2013-06-01

387

Ecological Uptake and Depuration of Carbon Nanotubes by Lumbriculus variegatus  

PubMed Central

Background Carbon nanotubes represent a class of nanomaterials having broad application potentials and documented cellular uptake and ecotoxicological effects that raise the possibility that they may bioaccumulate in living organisms. Objectives Radioactively labeled nanotubes were synthesized using a novel methane chemical vapor deposition procedure. Single-walled carbon nanotubes (SWNTs), multiwalled carbon nanotubes (MWNTs), and pyrene were spiked to sediment samples, and the respective uptake and depuration of these nanotubes and pyrene were assessed by the oligochaete, Lumbriculus variegatus. Results 14C-labeled carbon nanotubes were developed for these experiments to overcome significant previous limitations for quantifying nanotube materials in environmental and biological media. Biota-sediment accumulation factors for SWNTs and MWNTs were observed to be almost an order of magnitude lower than those for pyrene, a four-ringed polycyclic aromatic hydrocarbon (PAH). The depuration behaviors of the oligochaete suggested that the nanotubes detected in these organisms were associated with sediments remaining in the organism guts and not absorbed into cellular tissues as was the pyrene. The results suggest that, unlike PAHs, purified carbon nanotubes do not readily absorb into organism tissues. PMID:18414633

Petersen, Elijah J.; Huang, Qingguo; Weber, Walter J.

2008-01-01

388

Magnetotransport properties in magnetic nanotubes studied using Monte Carlo simulations  

NASA Astrophysics Data System (ADS)

The dependences of the magnetoelectric transport properties of nanotubes on the temperature, diameter and anisotropy were simulated using the Monte Carlo method, the Heisenberg model and the Drude formula. The simulations included the effects of an external magnetic field, magnetocrystalline anisotropy and nearest neighbor interactions. Two types of nanotubes with different unit cells (square and hexagonal) were implemented. The influence of the nanotube geometry was also analyzed. A smaller dependence of the resistivity on the nanotube diameter and magnetocrystalline anisotropy was observed for the square unit cell nanotubes compared to the results obtained for the hexagonal unit cell nanotubes. Furthermore, lower fluctuations in the resistivity were observed in the former. In contrast, an external magnetic field had a greater influence on the resistivity of the square unit cell nanotubes than for the hexagonal unit cell nanotubes.

Salazar-Enriquez, C. D.; Restrepo-Parra, E.; Restrepo, J.

2013-08-01

389

Synthesis and characterization of novel fullerenes and carbon nanotubes  

NASA Astrophysics Data System (ADS)

Since the discovery of Buckminsterfullerene, the soccerball shaped carbon-caged molecule consisting of 60 carbon atoms, there has been much speculation about the stability of other "fullerenes" with less than 60 carbon atoms. Although several fullerenes with greater than 60 carbon atoms have since been isolated in bulk, the only evidence of lower fullerenes has come from minute-quantity gas phase experiments. This thesis presents work on the first ever bulk synthesis, extraction and characterization of a lower fullerene: C36. By exploring the parameter space of the Kratschmer-Huffman graphite arc-discharge method, C36 was produced in milligram quantities. This new material which was extracted with pyridine was found by electron diffraction to form a covalently bonded solid with a d-spacing of 6.68 A. This material is electrically insulating in its pure form but it becomes conducting upon intercalation with alkali metals. The resistance vs temperature behavior of the alkali intercalated samples is consistent with variable range hopping. From microwave-loss measurements and current vs. voltage data, there are preliminary results that may indicate the presence of a very small superconducting fraction in these alkali doped samples. This result would be consistent with predictions by Grossman, Cote, Cohen and Louie that a certain isomer of C 36 with D6h symmetry has an exceptionally strong electron-phonon coupling constant. Other developments described in this thesis include a method of synthesizing multi-walled carbon nanotubes in high yield at an accelerated rate using a low pressure mixture of nitrogen and helium as the buffer gas. Also, a simple technique has been developed for synthesizing magnetic nickel-iron clusters that are coated with both electrical insulators and electrical conductors. These clusters may have a variety of applications in the fields of magnetic recording and biochemistry where magnetic manipulation of cells is important. Finally, a preliminary study of doping effects in multi-walled carbon nanotubes was conducted. This study showed that the transport properties of these nanotubes changed dramatically upon intercalation with both oxygen and potassium.

Piskoti, Charles Richard

390

Carbon monoxide-assisted growth of carbon nanotubes Y.H. Tang a,b  

E-print Network

Carbon monoxide-assisted growth of carbon nanotubes Y.H. Tang a,b , Y.F. Zheng a , C.S. Lee a , N, University of Western Ontario, London, Canada N6A 5B7 Received 17 February 2001 Abstract Carbon monoxide was used to synthesize carbon nanotubes (CNTs) in a hot-®lament chemical vapor deposition (HFCVD) system

Zheng, Yufeng

391

Carbon 40 (2002) 11231130 Scrolls and nested tubes in multiwall carbon nanotubes  

E-print Network

Carbon 40 (2002) 1123­1130 Scrolls and nested tubes in multiwall carbon nanotubes a a , b c *J of multiwalled carbon nanotubes (MWCNTs) reveal a class of defects analogous to edge dislocations in a crystal is not Van der Waals forces, as in the case of graphite or turbostratic carbon, but preservation of helicity

392

Removal of amorphous carbon for the efficient sidewall functionalisation of single-walled carbon nanotubes{  

E-print Network

of a sample of as-made single-walled carbon nanotubes (SWNTs) with nitric acid produces a uniformRemoval of amorphous carbon for the efficient sidewall functionalisation of single-walled carbon DOI: 10.1039/b712614j The sidewall functionalisation of carbon nanotubes using the standard nitric

Davis, Ben G.

393

Growing Aligned Carbon Nanotubes for Interconnections in ICs  

NASA Technical Reports Server (NTRS)

A process for growing multiwalled carbon nanotubes anchored at specified locations and aligned along specified directions has been invented. Typically, one would grow a number of the nanotubes oriented perpendicularly to a silicon integrated-circuit (IC) substrate, starting from (and anchored on) patterned catalytic spots on the substrate. Such arrays of perpendicular carbon nanotubes could be used as electrical interconnections between levels of multilevel ICs. The process (see Figure 1) begins with the formation of a layer, a few hundred nanometers thick, of a compatible electrically insulating material (e.g., SiO(x) or Si(y)N(z) on the silicon substrate. A patterned film of a suitable electrical conductor (Al, Mo, Cr, Ti, Ta, Pt, Ir, or doped Si), having a thickness between 1 nm and 2 m, is deposited on the insulating layer to form the IC conductor pattern. Next, a catalytic material (usually, Ni, Fe, or Co) is deposited to a thickness between 1 and 30 nm on the spots from which it is desired to grow carbon nanotubes. The carbon nanotubes are grown by plasma-enhanced chemical vapor deposition (PECVD). Unlike the matted and tangled carbon nanotubes grown by thermal CVD, the carbon nanotubes grown by PECVD are perpendicular and freestanding because an electric field perpendicular to the substrate is used in PECVD. Next, the free space between the carbon nanotubes is filled with SiO2 by means of CVD from tetraethylorthosilicate (TEOS), thereby forming an array of carbon nanotubes embedded in SiO2. Chemical mechanical polishing (CMP) is then performed to remove excess SiO2 and form a flat-top surface in which the outer ends of the carbon nanotubes are exposed. Optionally, depending on the application, metal lines to connect selected ends of carbon nanotubes may be deposited on the top surface. The top part of Figure 2 is a scanning electron micrograph (SEM) of carbon nanotubes grown, as described above, on catalytic spots of about 100 nm diameter patterned by electron-beam lithography. These and other nanotubes were found to have lengths ranging from 2 to 10 m and diameters ranging from 30 to 200 nm, the exact values of length depending on growth times and conditions and the exact values of diameter depending on the diameters and thicknesses of the catalyst spots. The bottom part of Figure 2 is an SEM of an embedded array of carbon nanotubes after CMP.

Li, Jun; Ye, Qi; Cassell, Alan; Ng, Hou Tee; Stevens, Ramsey; Han, Jie; Meyyappan, M.

2005-01-01

394

NMR Study of Single Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

^13C NMR experiments have been carried out for single-wall carbon nanotubes (SWNTs), which were produced by using non-ferromagnetic Rh-Pt mixed catalysts. Hydrogen peroxide was used to remove amorphous carbon particles in the raw soot almost perfectly. From the line shape analysis of the ^13C spectrum measured at 100.1MHz(9.4 T), the shift tensor was evaluated to be (?_11,?_22,?_33)=(192,186,132) ppm. Small anisotropic value(??= -57 ppm) compared with that reported for MWNTs suggests that this SWNTs sample contains metallic tubes with larger electronic density of states at the Fermi level than that of multi-wall carbon nanotubes(MWNTs) sample. We also performed ^13C spin lattice relaxation time(T_1) . It is found that SWNTs follows a Korringa-like behavior(T_1^o T=940^o60(sec.K)) in the temperature region between 4.2 K and 100 K. Alkali metal-doping effects and hydrogen uptake effects will be discussed.

Ogata, Hironori; Bandow, Syunji; Kuno, Shogo; Saito, Yahachi

2000-03-01

395

Theoretical study on the combined systems of peanut-shaped carbon nanotubes encapsulated in single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The combined systems of peanut-shaped carbon nanotubes encapsulated in both semiconducting and metallic single-walled carbon nanotubes are investigated by using self-consistent field crystal orbital method based on the density functional theory. The investigation indicates that the interaction between the two constituents is mainly contributed by the ? orbitals. The encapsulation does not change the semiconducting or metallic nature of the single-walled carbon nanotubes, but significantly changes the band dispersion and decreases the frontier band width of the metallic one. The carrier mobility and mean free path of the metallic single-walled carbon nanotube increase greatly after the encapsulation. The calculated mobilities have the order of 103 cm2 V-1 s-1 for both of the semiconducting and metallic double-walled carbon nanotubes.

Wang, Guo; Huang, Yuanhe

2012-10-01

396

Synthesis, characterization and electrochemical behavior of polypyrrole/carbon nanotube composites using organometallic-functionalized carbon nanotubes  

NASA Astrophysics Data System (ADS)

Thorn-like, organometallic-functionalized carbon nanotubes were successfully developed via a novel microwave hydrothermal route. The organometallic complex with methyl orange and iron (III) chloride served as reactive seed template, resulting in the oriented polymerization of pyrrole on the modified carbon nanotubes without the assistance of other oxidants. Morphological and structural characterizations of the carbon nanotube/methyl orange-iron (III) chloride and polypyrrole/carbon nanotube composites were examined using transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), infrared spectroscopy and X-ray diffraction (XRD). The electrochemical property of the polypyrrole/carbon nanotube composite was elucidated by cyclic voltammetry and galvanostatic charge-discharge. A specific capacitance of 304 F g -1 was obtained within the potential range of -0.5-0.5 V in 1 M KCl solution.

Mi, Hongyu; Zhang, Xiaogang; Xu, Youlong; Xiao, Fang

2010-01-01

397

Synthesis and characterization of double-walled carbon nanotubes from multi-walled carbon nanotubes by hydrogen-arc discharge  

Microsoft Academic Search

Double-walled carbon nanotubes (DWNTs) were synthesized in a large scale by a hydrogen arc discharge method using graphite powders or multi-walled carbon nanotubes\\/carbon nanofibers (MWNTs\\/CNFs) as carbon feedstock. The yield of DWNTs reached about 4g\\/h. We found that the DWNT product synthesized from MWNTs\\/CNFs has higher purity than that from graphite powders. The results from high-resolution transmission electron microscopy observations

Lixiang Li; Feng Li; Chang Liu; Hui-Ming Cheng

2005-01-01

398

Magnetic nanotubes and their potential use in neuroscience applications  

NASA Astrophysics Data System (ADS)

This paper presents our study on the synthesis and properties of magnetic nanotubes and their potential in neuroscience applications. Magnetic nanotubes were prepared by solution filtration through a template followed by thermal annealing and reduction. SEM and TEM were performed to characterize the as-prepared materials. To explore the potential use of magnetic nanotubes in neuroscience applications, we cultured neurons on iron oxide nanotube mats, and tested the effects of magnetic nanotubes on the growth of neurons. Based on our preliminary result, three original approaches for investigating and modulating neuron activities using magnetic nanotubes are proposed. The progress in this area of investigation could help to find better treatment for diseases in nervous systems in the future.

Chen, Linfeng; Xie, Jining; Srivatsan, Malathi; Varadan, Vijay K.

2006-03-01

399

Chemical functionalization of carbon nanotubes through energetic radical collisions  

NASA Astrophysics Data System (ADS)

Classical molecular dynamics simulations are used to model the bombardment of a bundle of single walled carbon nanotubes by CH3 radicals impacting with incident energies of 10, 45, and 80 eV. The simulations show that there is a high probability of adhesion of either the radicals or their fragments to the nanotube walls at all the incident energies considered. They therefore predict a pathway to the chemical functionalization of the walls of carbon nanotubes. The simulations also show how at 80 eV the incident radicals can induce cross-linking between the nanotubes.

Ni, Boris; Sinnott, Susan B.

2000-06-01

400

Carbon nanotube oscillator surface profiling device and method of use  

DOEpatents

The proposed device is based on a carbon nanotube oscillator consisting of a finite length outer stationary nanotube and a finite length inner oscillating nanotube. Its main function is to measure changes in the characteristics of the motion of the carbon nanotube oscillating near a sample surface, and profile the roughness of this surface. The device operates in a non-contact mode, thus it can be virtually non-wear and non-fatigued system. It is an alternative to the existing atomic force microscope (AFM) tips used to scan surfaces to determine their roughness.

Popescu, Adrian (Tampa, FL); Woods, Lilia M. (Tampa, FL); Bondarev, Igor V. (Fuquay Varina, NC)

2011-11-15

401

Low-Temperature Plasma Functionalization of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

A low-temperature plasma process has been devised for attaching specified molecular groups to carbon nanotubes in order to impart desired chemical and/or physical properties to the nanotubes for specific applications. Unlike carbon-nanotube- functionalization processes reported heretofore, this process does not involve the use of wet chemicals, does not involve exposure of the nanotubes to high temperatures, and generates very little chemical residue. In addition, this process can be carried out in a relatively simple apparatus and can readily be scaled up to mass production.

Khare, Bishun; Meyyappan, M.

2004-01-01

402

Polyglycerol-derived amphiphiles for single walled carbon nanotube suspension  

NASA Astrophysics Data System (ADS)

Inspired by the commercially available SDS surfactant, a new polyglycerol-derived amphiphile has been synthesized for functionalizing carbon nanotubes. SDS' sulphate group was replaced by a polyglycerol dendron. The steric hindrance offered by the dendrons makes the compound much more efficient than SDS in isolating and stabilizing nanotubes in solution. Further amphiphiles have been synthesized by adding small aromatic moieties between head and tail groups. We show that this addition leads to selective interaction between surfactants and carbon nanotubes. Excitation photoluminescence and optical absorption spectroscopy analysis confirm the change in the distribution of nanotubes' chiralities in suspension, depending on the amphiphile.

Setaro, A.; Popeney, C. S.; Trappmann, B.; Datsyuk, V.; Haag, R.; Reich, S.

2010-06-01

403

Carbon Nanotubes as Schottky Barrier Transistors  

NASA Astrophysics Data System (ADS)

Field-effect transistors (FETs) made with carbon nanotubes have many attractive features, and are being widely studied as a potential nanoscale successor to silicon FETs. Remarkably, we found that nanotube FETs generally operate by a completely different principle than ordinary Si FETs. Rather than modulate the conductance of the channel, the gate field acts to modulate the tunneling conductance of a Schottky barrier at the contact [1]. As a result, the device performance is determined by completely different factors than in familiar FETs [2-4]. In particular, the nanoscale electric field distribution near the contacts plays a crucial role. As a result, the geometry and workfunction of the contact become as important as more familiar factors like gate-oxide thickness. In addition, there are fundamental differences in the role of Fermi-level pinning at the metal-nanotube contact, compared to ordinary semiconductor interfaces [5]. 1. S. Heinze, J. Tersoff, R. Martel, V. Derycke, J. Appenzeller, and Ph. Avouris, Phys. Rev. Lett. 89, 106801 (2002). 2. S. Heinze, M. Radosavljevic, J. Tersoff, and Ph. Avouris, Phys. Rev. B 68, 235418 (2003). 3. M. Radosavljevic, S. Heinze, J. Tersoff, and Ph. Avouris, Appl. Phys. Lett. 83, 2435 (2003). 4. S. Heinze, J. Tersoff, and Ph. Avouris, Appl. Phys. Lett. 83, 5038 (2003). 5. F. Leonard and J. Tersoff, Phys. Rev. Lett. 84, 4693 (2000).

Tersoff, Jerry

2005-03-01

404

Application of Carbon Nanotubes to Nylon Composite  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) have many interesting mechanical properties. Therefore, it is expected that an excellent characteristic can be demonstrated by small addition of CNTs in various composite materials. In this study, nylon-6 (N6) was used as the base material and CNTs were mixed to it as a reinforcing agent. Three kinds of CNT were used as filler. Single-wall nanotubes (SWNTs) produced by arc plasma jet (APJ) method, SWNTs produced by ferrum-hydrogen arc (FHA) method, and multiwalled nanotubes (MWNTs) produced by chemical vapor deposition (CVD). Mechanical properties of the composites were measured by tension test, bending test and impact test. In general, when tensile or bending strength goes high, the value of impact energy falls. However, in the case of APJ-SWNT mixing in N6, the impact energy also increases together with the tensile and bending strengths. This study, thus, suggests that APJ-SWNT possesses a characteristic due to which the composite material is strengthened without losing its toughness.

Suzuki, Tomoko; Inoue, Sakae; Nojima, Kazuhiro; Tsuchimoto, Akiharu; Chen, Beibei; Kumar, Mukul; Ando, Yoshinori

2011-01-01

405

Cell mobility after endocytosis of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Directed cell movement plays a crucial role in cellular behaviors such as neuronal cell division, cell migration, and cell differentiation. There is evidence in preclinical in vivo studies that small fields have successfully been used to enhance regrowth of damages spinal cord axons but with a small success rate. Fortunately, the evolution of functional biomaterials and nanotechnology may provide promising solutions for enhancing the application of electric fields in guiding neuron migration and neurogenesis within the central nervous system. In this work, we studied how endocytosis and subsequent retention of carbon nanotubes affects the mobility of cells under the influence of an electric field, including the directed cell movement.

Pirbhai, Massooma; Flores, Thomas; Jedlicka, Sabrina; Rotkin, Slava V.

2013-03-01

406

Metallic Carbon Nanotubes and Ag Nanocrystals  

SciTech Connect

The goal of this DOE solar energy research was to understand how visible light interacts with matter, and how to make electric excitations evolve into separated electrons and holes in photovoltaic cells, especially in nanoparticles and nanowires. Our specific experiments focused on A) understanding plasmon enhanced spectroscopy and charge-transfer (metal-to-molecule) photochemistry on the surface of metallic particles and B) the spectroscopy and photochemistry of carbon nanotubes and graphene. I also worked closely with R. Friesner on theoretical studies of photo-excited electrons near surfaces of titanium dioxide nanoparticles; this process is relevant to the Gratzel photovoltaic cell.

Brus, Louis E

2014-03-04

407

Ultrastrong, Stiff and Multifunctional Carbon Nanotube Composites  

SciTech Connect

Carbon nanotubes (CNTs) are an order of magnitude stronger than any current engineering fiber. However, for the past two decades it has been a challenge to utilize their reinforcement potential in composites. Here we report CNT composites with unprecedented multifunctionalities, including record high strength (3.8 GPa), Young s modulus (293 GPa), electrical conductivity (1230 S cm-1) and thermal conductivity (41 W m-1 K-1). These superior properties are derived from the long length, high volume fraction, good alignment and reduced waviness of the CNTs, which were produced by a novel processing approach that can be easily scaled up for industrial production.

Wang, Xin [North Carolina State University; Yong, Zhenzhong [Suzhou Institute of Nano-Tech and Nano-Bionics; Li, Qingwen [Suzhou Institute of Nano-Tech and Nano-Bionics; Bradford, Philip D. [North Carolina State University; Liu, Wei [Donghua University, Shanghai, China; Tucker, Dennis S. [Tucker Technical Solutions; Cai, Wei [ORNL; Wang, Hsin [ORNL; Yuan, Fuh-Gwo [North Carolina State University; Zhu, Yuntian [North Carolina State University

2012-01-01

408

Carbon Nanotubes Reinforced Composites for Biomedical Applications  

PubMed Central

This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matrix composites, and CNTs reinforced ceramic matrix composites), their mechanical properties, cell experiments in vitro, and biocompatibility tests in vivo. PMID:24707488

Wang, Wei; Zhu, Yuhe; Liao, Susan; Li, Jiajia

2014-01-01

409

Carbon nanotube seeded silicon crystal growth  

NASA Astrophysics Data System (ADS)

Crystal growth of liquid silicon on the heterogeneous surfaces of carbon nanotubes (CNTs) is simulated. Silicon atoms are concentrated to form perfect coaxial cylindrical configurations around CNT cores. The heredity effect makes silicon imprint cylindrical shapes of CNTs during the solidification. The CNTs have a great influence on the stacking sequence of silicon atoms. Growth competition between CNT cores is clearly observed, which results in defects at the shared interface. The internal potential field around CNTs is responsible for growth competition and the heredity effect.

Li, Y. F.; Li, H.; Sun, F. W.; Zhang, X. Q.; Liew, K. M.

2011-07-01

410

Fibrous composites comprising carbon nanotubes and silica  

DOEpatents

Fibrous composite comprising a plurality of carbon nanotubes; and a silica-containing moiety having one of the structures: (SiO).sub.3Si--(CH.sub.2).sub.n--NR.sub.1R.sub.2) or (SiO).sub.3Si--(CH.sub.2).sub.n--NCO; where n is from 1 to 6, and R.sub.1 and R.sub.2 are each independently H, CH.sub.3, or C.sub.2H.sub.5.

Peng, Huisheng (Shanghai, CN); Zhu, Yuntian Theodore (Cary, NC); Peterson, Dean E. (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM)

2011-10-11

411

Increased Alignment in Carbon Nanotube Growth  

NASA Technical Reports Server (NTRS)

Method and system for fabricating an array of two or more carbon nanotube (CNT) structures on a coated substrate surface, the structures having substantially the same orientation with respect to a substrate surface. A single electrode, having an associated voltage source with a selected voltage, is connected to a substrate surface after the substrate is coated and before growth of the CNT structures, for a selected voltage application time interval. The CNT structures are then grown on a coated substrate surface with the desired orientation. Optionally, the electrode can be disconnected before the CNT structures are grown.

Delzeit, Lance D. (Inventor)

2007-01-01

412

Superhydrophobic conductive carbon nanotube coatings for steel.  

PubMed

We report the synthesis of superhydrophobic coatings for steel using carbon nanotube (CNT)-mesh structures. The CNT coating maintains its structural integrity and superhydrophobicity even after exposure to extreme thermal stresses and has excellent thermal and electrical properties. The coating can also be reinforced by optimally impregnating the CNT-mesh structure with cross-linked polymers without significantly compromising on superhydrophobicity and electrical conductivity. These superhydrophobic conductive coatings on steel, which is an important structural material, open up possibilities for many new applications in the areas of heat transfer, solar panels, transport of fluids, nonwetting and nonfouling surfaces, temperature resilient coatings, composites, water-walking robots, and naval applications. PMID:19281157

Sethi, Sunny; Dhinojwala, Ali

2009-04-21

413

Cross-linked carbon nanotube heat spreader  

NASA Astrophysics Data System (ADS)

Isolated individual carbon nanotubes (CNTs) have shown exceptional thermal conductivity along their axis, but have poor thermal transfer between adjacent CNTs. Thick bundles of aligned CNTs have been used as heat pipes, but the thermal input and output areas are the same, providing no heat spreading effect. Energetic argon ion beams are used to join, or cross-link overlapping CNTs in a thick film to form an interpenetrating network with an isotropic thermal conductivity of 2150 W/m-K. Such thick films may be used as heat spreaders to enlarge the thermal footprint of various electronic and semiconductor devices, laser diodes and CPU chips, for example, to enhance cooling.

Konesky, Gregory

2014-09-01

414

Complex Multifunctional Polymer/Carbon-Nanotube Composites  

NASA Technical Reports Server (NTRS)

A methodology for developing complex multifunctional materials that consist of or contain polymer/carbon-nanotube composites has been conceived. As used here, "multifunctional" signifies having additional and/or enhanced physical properties that polymers or polymer-matrix composites would not ordinarily be expected to have. Such properties include useful amounts of electrical conductivity, increased thermal conductivity, and/or increased strength. In the present methodology, these properties are imparted to a given composite through the choice and processing of its polymeric and CNT constituents.

Patel, Pritesh; Balasubramaniyam, Gobinath; Chen, Jian

2009-01-01

415

Thermodynamics on Soluble Carbon Nanotubes: How Do DNA Molecules Replace Surfactants on Carbon Nanotubes?  

NASA Astrophysics Data System (ADS)

Here we represent thermodynamics on soluble carbon nanotubes that enables deep understanding the interactions between single-walled carbon nanotubes (SWNTs) and molecules. We selected sodium cholate and single-stranded cytosine oligo-DNAs (dCn (n = 4, 5, 6, 7, 8, 10, 15, and 20)), both of which are typical SWNT solubilizers, and successfully determined thermodynamic properties (?G, ?H and ?S values) for the exchange reactions of sodium cholate on four different chiralities of SWNTs ((n,m) = (6,5), (7,5), (10,2), and (8,6)) for the DNAs. Typical results contain i) the dC5 exhibited an exothermic exchange, whereas the dC6, 8, 10, 15, and 20 materials exhibited endothermic exchanges, and ii) the energetics of the dC4 and dC7 exchanges depended on the associated chiral indices and could be endothermic or exothermic. The presented method is general and is applicable to any molecule that interacts with nanotubes. The study opens a way for science of carbon nanotube thermodynamics.

Kato, Yuichi; Inoue, Ayaka; Niidome, Yasuro; Nakashima, Naotoshi

2012-10-01

416

Progress toward Making Epoxy/Carbon-Nanotube Composites  

NASA Technical Reports Server (NTRS)

A modicum of progress has been made in an effort to exploit single-walled carbon nanotubes as fibers in epoxy-matrix/fiber composite materials. Two main obstacles to such use of carbon nanotubes are the following: (1) bare nanotubes are not soluble in epoxy resins and so they tend to agglomerate instead of becoming dispersed as desired; and (2) because of lack of affinity between nanotubes and epoxy matrices, there is insufficient transfer of mechanical loads between the nanotubes and the matrices. Part of the effort reported here was oriented toward (1) functionalization of single-walled carbon nanotubes with methyl methacrylate (MMA) to increase their dispersability in epoxy resins and increase transfer of mechanical loads and (2) ultrasonic dispersion of the functionalized nanotubes in tetrahydrofuran, which was used as an auxiliary solvent to aid in dispersing the functionalized nanotubes into a epoxy resin. In another part of this effort, poly(styrene sulfonic acid) was used as the dispersant and water as the auxiliary solvent. In one experiment, the strength of composite of epoxy with MMA-functionalized-nanotubes was found to be 29 percent greater than that of a similar composite of epoxy with the same proportion of untreated nanotubes.

Tiano, Thomas; Roylance, Margaret; Gassner, John; Kyle, William

2008-01-01

417

Hofstadter butterflies of carbon nanotubes: Pseudofractality of the magnetoelectronic spectrum  

NASA Astrophysics Data System (ADS)

The electronic spectrum of a two-dimensional square lattice in a perpendicular magnetic field has become known as the Hofstadter butterfly [Hofstadter, Phys. Rev. B 14, 2239 (1976).]. We have calculated quasi-one-dimensional analogs of the Hofstadter butterfly for carbon nanotubes (CNTs). For the case of single-wall CNTs, it is straightforward to implement magnetic fields parallel to the tube axis by means of zone folding in the graphene reciprocal lattice. We have also studied perpendicular magnetic fields which, in contrast to the parallel case, lead to a much richer, pseudofractal spectrum. Moreover, we have investigated magnetic fields piercing double-wall CNTs and found strong signatures of interwall interaction in the resulting Hofstadter butterfly spectrum, which can be understood with the help of a minimal model. Ubiquitous to all perpendicular magnetic field spectra is the presence of cusp catastrophes at specific values of energy and magnetic field. Resolving the density of states along the tube circumference allows recognition of the snake states already predicted for nonuniform magnetic fields in the two-dimensional electron gas. An analytic model of the magnetic spectrum of electrons on a cylindrical surface is used to explain some of the results.

Nemec, Norbert; Cuniberti, Gianaurelio

2006-10-01

418

Electrocatalytic reduction of NAD + at glassy carbon electrode modified with single-walled carbon nanotubes and Ru(III) complexes  

Microsoft Academic Search

A simple procedure was developed to prepare a glassy carbon electrode modified with carbon nanotubes and Ruthenium (III) complexes.\\u000a First, 25 ?l of dimethyl sulfoxide–carbon nanotubes solutions (0.4 mg\\/ml) was cast on the surface of the glassy carbon electrode\\u000a and dried in air to form a carbon nanotube film at the electrode surface. Then, the glassy carbon\\/carbon nanotube-modified\\u000a electrode was immersed into

Abdollah Salimi; Mohadeseh Izadi; Rahman Hallaj; Saied Soltanian; Hassan Hadadzadeh

2009-01-01

419

Thermionic Emission of Single-Wall Carbon Nanotubes Measured  

NASA Technical Reports Server (NTRS)

Researchers at the NASA Glenn Research Center, in collaboration with the Rochester Institute of Technology, have investigated the thermionic properties of high-purity, single-wall carbon nanotubes (SWNTs) for use as electron-emitting electrodes. Carbon nanotubes are a recently discovered material made from carbon atoms bonded into nanometer-scale hollow tubes. Such nanotubes have remarkable properties. An extremely high aspect ratio, as well as unique mechanical and electronic properties, make single-wall nanotubes ideal for use in a vast array of applications. Carbon nanotubes typically have diameters on the order of 1 to 2 nm. As a result, the ends have a small radius of curvature. It is these characteristics, therefore, that indicate they might be excellent potential candidates for both thermionic and field emission.

Landis, Geoffrey A.; Krainsky, Isay L.; Bailey, Sheila G.; Elich, Jeffrey M.; Landi, Brian J.; Gennett, Thomas; Raffaelle, Ryne P.

2004-01-01

420

Electrochemical oxidation and nanomolar detection of acetaminophen at a carbon-ceramic electrode modified by carbon nanotubes: a comparison between multi walled and single walled carbon nanotubes  

Microsoft Academic Search

Carbon-ceramic electrodes (CCE) modified with carbon nanotubes were prepared, and the electrochemical behavior towards acetaminophen\\u000a (ACOP) was investigated using both a bare CCE and electrodes modified with either single walled carbon nanotubes (SWCNT) or\\u000a multi walled carbon nanotubes (MWCNT) in an effort to understand which of them is the better choice in terms of electrocatalyzing\\u000a the oxidation of ACOP, and

Biuck Habibi; Mojtaba Jahanbakhshi; Mohammad Hossein Pournaghiazar

2011-01-01

421

Multiferroicity of Carbon-Based Charge-Transfer Magnets.  

PubMed

A new type of carbon charge-transfer magnet, consisting of a fullerene acceptor and single-walled carbon nanotube donor, is demonstrated, which exhibits room temperature ferromagnetism and magnetoelectric (ME) coupling. In addition, external stimuli (electric/magnetic/elastic field) and the concentration of a nanocarbon complex enable the tunabilities of the magnetization and ME coupling due to the control of the charge transfer. PMID:25389110

Qin, Wei; Gong, Maogang; Chen, Xiaomin; Shastry, Tejas A; Sakidja, Ridwan; Yuan, Guoliang; Hersam, Mark C; Wuttig, Manfred; Ren, Shenqiang

2014-11-11

422

Fabrication of mesoporous and high specific surface area lanthanum carbide-carbon nanotube composites  

NASA Astrophysics Data System (ADS)

Mesoporous lanthanum carbide-carbon nanotube composites were produced by means of carbothermal reaction of lanthanum oxide, graphite and multi-walled carbon nanotube mixtures under high vacuum. Residual gas analysis revealed the higher reactivity of lanthanum oxide towards carbon nanotubes compared to graphite. After sintering, the composites revealed a specific surface area increasing with the amount of carbon nanotubes introduced. The meso-porosity of carbon nanotubes was maintained after thermal treatment.

Biasetto, L.; Carturan, S.; Maggioni, G.; Zanonato, P.; Di Bernardo, P.; Colombo, P.; Andrighetto, A.; Prete, G.

2009-04-01

423

Fabrication and characterization of single carbon nanotube emitters as point electron sources  

E-print Network

a producing micron-size carbon fibers which contain single carbon nanotubes at their cores by a chemical vapor of the fractured carbon fiber, a multiwalled nanotube sticks out due to its different fracture toughness from the carbon fiber that is largely made of amorphous carbon. The pro- truded carbon nanotubes are usually 4

Qin, Lu-Chang

424

Illuminating the future of silicon photonics: optical coupling of carbon nanotubes to microrings  

NASA Astrophysics Data System (ADS)

Advances in carbon nanotube material quality and processing techniques have led to an increased interest in nanotube photonics. In particular, emission in the telecommunication wavelengths makes nanotubes compatible with silicon photonics. Noury et al (2014 Nanotechnology 25 215201) have reported on carbon nanotube photoluminescence coupled to silicon microring resonators, underscoring the advantage of combining carbon nanotube emitters with silicon photonics. Their results open up the possibility of using nanotubes in other waveguide-based devices, taking advantage of well-established technologies.

Kato, Y. K.

2015-02-01

425

Multiscale modeling of carbon nanotube reinforced polymer composites.  

PubMed

This article examines the effect of interfacial load transfer on the stress distribution in carbon nanotube/polymer composites through a stress analysis of the nanotube/matrix system. Both isostrain and isostress loading conditions are investigated. The nanotube is modeled by the molecular structural mechanics method at the atomistic level. The matrix is modeled by the finite element method, and the nanotube/matrix interface is assumed to be bonded either perfectly or by van der Waals interactions. The fundamental issues examined include the interfacial shear stress distribution, stress concentration in the matrix in the vicinity of nanotube ends, axial stress profile in the nanotube, and the effect of nanotube aspect ratio on load transfer. PMID:14733155

Li, Chunyu; Chou, Tsu-Wei

2003-10-01

426

Channeling of protons in radially compressed carbon nanotubes  

NASA Astrophysics Data System (ADS)

Channeling of 10 MeV protons in radially compressed chiral carbon nanotubes is considered. Monte Carlo simulation program is used for the calculation of the trajectories, energy losses and angular distributions of protons in nanotubes of various lengths, where the potential in Doyle-Turner approximation is used to describe the interaction between a proton and a nanotube. Calculations were carried out for different incident angles between proton beam and the nanotube axis. The results show that a decreased angular distribution of the beam is observed, compared with propagation through a straight nanotube, in case when it enters from the compressed end of the nanotube. The energy and spatial distribution of channeled protons in compressed nanotubes is examined.

Karabarbounis, A.; Sarros, S.; Trikalinos, Ch

2014-05-01

427

Carbon nanotubes enhanced the lead toxicity on the freshwater fish  

NASA Astrophysics Data System (ADS)

Carbon nanotubes are promising nanostructures for many applications in materials industry and biotechnology. However, it is mandatory to evaluate their toxicity and environmental implications. We evaluated nitric acid treated multiwalled carbon nanotubes (HNO3-MWCNT) toxicity in Nile tilapia (Oreochromis niloticus) and also the lead (Pb) toxicity modulation after the nanotube interaction. Industrial grade multiwalled carbon nanotubes [Ctube 100, CNT Co. Ltd] were treated with 9M HNO3 for 12h at 150°C to generate oxygenated groups on the nanotube surface, to improve water dispersion and heavy metal interaction. The HNO3-treated multiwalled carbon nanotubes were physico-chemically characterized by several techniques [e.g. TEM, FE-SEM, TGA, ?-potential and Raman spectroscopy]. HNO3-MWCNT did not show toxicity on Nile tilapia when the concentration ranged from 0.1 to 3.0 mg/L, and the maximum exposure time was 96h. After 24, 48, 72 and 96h the LC50 values of Pb were 1.65, 1.32, 1.10 and 0.99 mg/L, respectively. To evaluate the Pb-nanotube interaction influence on the ecotoxicity, we submitted the Nile tilapia to different concentrations of Pb mixed with a non-toxic concentration of HNO3-MWCNT (1.0 mg/L). After 24, 48, 72, 96 h the LC50 values of Pb plus nanotubes were: 0.32, 0.25, 0.20, 0.18 mg/L, respectively. These values showed a synergistic effect after Pb-nanotube interaction since Pb toxicity increased over five times. X-ray energy dispersive spectroscopy (EDS) was used to confirm lead adsorption on the carbon nanotube oxidized surface. The exposure of Nile tilapia to Pb plus HNO3-MWCNT caused both oxygen consumption and ammonium excretion decrease, when compared to the control. Finally, our results show that carbon nanotubes interact with classical pollutants drawing attention to the environmental implications.

Martinez, D. S. T.; Alves, O. L.; Barbieri, E.

2013-04-01

428

Photomechanical responses of carbon nanotube/polymer actuators  

NASA Astrophysics Data System (ADS)

Recent studies have investigated the photomechanical properties of carbon nanotubes which can be utilized to construct optical actuators. In this paper we compare the photomechanical response from single-wall and multi-wall carbon nanotube/polymer systems in multilayer and nanocomposite actuator constructions. Incorporating polymers in the actuators, single-wall and multi-wall nanotubes show similar photomechanical responses, which are directly related to prestrain and nanotube alignments. Nanotube/polymer multilayered actuators exhibit comparable actuation strokes to the nanocomposite counterparts, while enabling easier sample construction, intact polymer and nanotube properties, and compatibility to CMOS/MEMS processes. The photomechanical responses can be well understood based on affine modelling of photomechanical responses.

Lu, Shaoxin; Panchapakesan, Balaji

2007-08-01

429

Heat transport and thermal management in single walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Results from our investigation of thermal transport in CVD grown Single-Walled Carbon nanotubes (SWNT) on different substrates will be reported. Chiu et al. recently showed that multi-walled carbon nanotube devices cool by ballistic phonon heat transport. To harness the remarkable thermal properties of nanotubes for thermal management, it is of interest to understand how heat energy is transported into or out of nanotubes. In this work, we investigate the breakdown power for SWNT nanotube devices using different substrate materials to determine the effect of substrate thermal conductivity on nanotube breakdown. We compare our results with those obtained with the Si/ SiO2 substrate. Our results indicate higher power dissipation on a sapphire substrate for few micron SWNTs but lower than expected dissipation for the longer length scales. We will discuss the mechanism of power dissipation and thermal transport in our devices in light of our results.

Maune, Hareem; Bockrath, Marc

2006-03-01

430

Light Emission from Carbon Nanotube Field Effect Transistors  

NASA Astrophysics Data System (ADS)

Since their discovery in 1991, research in carbon nanotubes has grown rapidly. Part of this interest is driven by the remarkable electrical and mechanical properties demonstrated by carbon nanotubes which could have significant technological impact (1,2). Recent progress has included demonstrations of interesting opto-electronic properties of carbon nanotubes. In one experiment we have shown that single carbon nanotubes can be a source of infrared optical emission (3). We have also shown how a single carbon nanotube can be used as a photoconductive detector (4). In this talk, we will examine the opto-electronic properties of individual single wall carbon nanotubes. (1) M.S. Dresselhaus, G. Dresselhaus, and Ph. Avouris (eds.), "Carbon Nanotubes", Topics Appl. Phys. 80, (2001). (2) Ph. Avouris, Acct. Chem. Res. 35, 1026 (2002). (3) J.A. Misewich, R. Martel, Ph. Avouris, J. Tsang, S. Heinze, and J. Tersoff, Science 300, 783 (2003). (4) M. Freitag, Y. Martin, J.A. Misewich, R. Martel, and Ph. Avouris, Nanoletters 3, 1067 (2003).

Misewich, James

2004-03-01

431

Carbon nanotube-reinforced composites: Processing, characterization and modeling  

NASA Astrophysics Data System (ADS)

The exceptionally high specific stiffness and strengths reported for carbon nanotubes, combined with their fiber-like structure, has stimulated research in the development of polymer nanocomposites reinforced with carbon nanotubes. Before these extraordinary properties observed at the nano-scale are realized in a macroscopic composite, considerable basic research is necessary. This research work seeks to obtain a fundamental understanding of the processing/structure/property relations in carbon nanotube-reinforced composites through integrated research on processing and characterization of model nanocomposite systems as well as development of predictive models for the nanocomposite elastic properties. Ultimately, establishment of these basic relationships will enable the nanoscale design of nanotube-reinforced materials. In this work, a novel technique to produce continuous nanocomposite ribbons of aligned multi-walled carbon nanotubes embedded in a polystyrene thermoplastic matrix was developed. This model nanocomposite system serves as a basis for the investigation of structure/property relationships through characterization of their elastic and fracture behavior. Based on characterization results and numerical simulations, a micromechanics-based modeling technique is developed to describe the structure/size influence of the nanotube reinforcement on the elastic modulus of these nanocomposites. To reveal the hierarchy of nanotube reinforcement, multi-scale hybrid composites, where a nanotube composite sheath surrounds traditional carbon fibers, were produced and the influence of selective reinforcement on load transfer at the fiber/matrix interface was examined.

Thostenson, Erik T.

432

Protein stability at a carbon nanotube interface.  

PubMed

The interactions of proteins with solid surfaces occur in a variety of situations. Motivated by the many nanoengineering applications of protein-carbon nanotube hybrids, we investigate the conformational transitions of hen egg white lysozyme adsorbed on a carbon nanotube. Using a C(?) structure-based model and replica exchange molecular dynamics, we show how the folding/unfolding equilibrium of the adsorbed protein varies with the strength of its coupling to the surface. The stability of the native state depends on the balance between the favorable entropy and unfavorable enthalpy change on adsorption. In the case of a weakly attractive surface when the former dominates, the protein is stabilized. In this regime, the protein can fold and unfold while maintaining the same binding fraction. With increasing surface attraction, the unfavorable enthalpic effect dominates, the native state is destabilized, and the protein has to extensively unbind before changing states from unfolded to folded. At the highest surface coupling, the entropic penalty of folding vanishes, and a folding intermediate is strongly stabilized. In this intermediate state, the ?-domain of lysozyme is disrupted, while the ?-sheet remains fully structured. We rationalize the relative stability of the two domains on the basis of the residue contact order. PMID:21456701

Vaitheeswaran, S; Garcia, A E

2011-03-28

433

X-ray generation using carbon nanotubes  

NASA Astrophysics Data System (ADS)

Since the discovery of X-rays over a century ago the techniques applied to the engineering of X-ray sources have remained relatively unchanged. From the inception of thermionic electron sources, which, due to simplicity of fabrication, remain central to almost all X-ray applications, there have been few fundamental technological advances. However, with the emergence of ever more demanding medical and inspection techniques, including computed tomography and tomosynthesis, security inspection, high throughput manufacturing and radiotherapy, has resulted in a considerable level of interest in the development of new fabrication methods. The use of conventional thermionic sources is limited by their slow temporal response and large physical size. In response, field electron emission has emerged as a promising alternative means of deriving a highly controllable electron beam of a well-defined distribution. When coupled to the burgeoning field of nanomaterials, and in particular, carbon nanotubes, such systems present a unique technological opportunity. This review provides a summary of the current state-of-the-art in carbon nanotube-based field emission X-ray sources. We detail the various fabrication techniques and functional advantages associated with their use, including the ability to produce ever smaller electron beam assembles, shaped cathodes, enhanced temporal stability and emergent fast-switching pulsed sources. We conclude with an overview of some of the commercial progress made towards the realisation of an innovative and disruptive technology.

Parmee, Richard J.; Collins, Clare M.; Milne, William I.; Cole, Matthew T.

2015-01-01

434

Thermo-electromagnetic sound transducer based on carbon nanotube sheet  

NASA Astrophysics Data System (ADS)

Multi-walled carbon nanotube sheet stretched between conductive rods was placed in magnetic field and excited with alternating electrical current to obtain hybrid thermo-electromagnetic sound transducer (TEMST). Unlike quite common thermoacoustic (TA) device capable of conversion of heat into acoustic signal, sound generation in explored design is provided by diaphragm-like oscillations of thermally excited sheet induced by the electromagnetic Lorentz force. This results in the interference of TA and Lorentz force-driven contributions causing substantial variation of intensity and spatial distribution of first harmonic of emitted signal. Acoustic spectra and sound propagation direction for TEMST device can be controlled by applied bias voltage that is beneficial for diverse sound management applications. Observed dependence of acoustic amplitude on field strength can be used for magnetic sensing.

Kozlov, Mikhail; Oh, Jiyoung

2014-09-01

435

Absolute Rayleigh Intensity and Uniform Optical Conductivity in Carbon Nanotubes  

Microsoft Academic Search

We used a novel on-chip Rayleigh imaging technique to measure the absolute intensity of Rayleigh scattering of single-walled carbon nanotubes. The spatial distribution of the radiation scattered by the nanotubes is determined by their shape, but the intensity and spectrum of the scattered radiation are determined by exciton dynamics, quantum-dot-like optical resonances and other intrinsic properties. Moreover, the nanotubes display

Lihong Herman; Daniel Joh; Jesse Kinder; Sang-Yong Ju; Michael Segal; Jeffreys Johnson; Garnet Chan; Jiwoong Park

2011-01-01

436

Photon enhanced aggregation of single walled carbon nanotube dispersions  

SciTech Connect

The authors describe a photon enhanced aggregation of dispersed single walled carbon nanotubes in the presence of electron transfer reagents. A recently synthesized metallodendrimer strongly and specifically binds to the ends of the nanotubes. Upon optical excitation, of the metal to ligand charge transfer absorption, of various ruthenium complexes, the nanotubes rapidly coagulate. The electron transfer mechanism is consistent with observed photon enhancement process. These results support a directed self-assembly paradigm for nanostructured materials.

Chaturvedi, H.; Poler, J. C. [Department of Chemistry, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, North Carolina 28223-0001 and Center for Optoelectronics and Optical Communications, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, North Carolina 28223-0001 (United States)

2007-05-28

437

Thermal conduction phenomena in carbon nanotubes and related nanostructured materials  

NASA Astrophysics Data System (ADS)

The extremely high thermal conductivities of carbon nanotubes have motivated a wealth of research. Progress includes innovative conduction metrology based on microfabricated platforms and scanning thermal probes as well as simulations exploring phonon dispersion and scattering using both transport theory and molecular dynamics. This article highlights these advancements as part of a detailed review of heat conduction research on both individual carbon nanotubes and nanostructured films consisting of arrays of nanotubes or disordered nanotube mats. Nanotube length, diameter, and chirality strongly influence the thermal conductivities of individual nanotubes and the transition from primarily diffusive to ballistic heat transport with decreasing temperature. A key experimental challenge, for both individual nanotubes and aligned films, is the separation of intrinsic and contact resistances. Molecular dynamics simulations have studied the impacts of specific types of imperfections on the nanotube conductance and its variation with length and chirality. While the properties of aligned films fall short of predictions based on individual nanotube data, improvements in surface engagement and postfabrication nanotube quality are promising for a variety of applications including mechanically compliant thermal contacts.

Marconnet, Amy M.; Panzer, Matthew A.; Goodson, Kenneth E.

2013-07-01

438

Growing carbon nanotubes by microwave plasma-enhanced chemical vapor deposition  

E-print Network

nanotubes are the stiffest material known to date. Electronically, a carbon nanotube can behave eitherGrowing carbon nanotubes by microwave plasma-enhanced chemical vapor deposition L. C. Qin,a) D 1998 A processing route has been developed to grow bundles of carbon nanotubes on substrates from

Qin, Lu-Chang

439

Synthesis and Electronic Transport in Known Chirality Single Wall Carbon Nanotubes  

E-print Network

Synthesis and Electronic Transport in Known Chirality Single Wall Carbon Nanotubes Bhupesh Chandra;ABSTRACT Synthesis and Electronic Transport in Known Chirality Single Wall Carbon Nanotubes Bhupesh Chandra and unbundled single wall carbon nanotubes. Two technological applications which directly utilize nanotubes

Hone, James

440

Photoconductivity of single-wall carbon nanotubes under continuous-wave near-infrared illumination  

E-print Network

Photoconductivity of single-wall carbon nanotubes under continuous-wave near-infrared illumination 2003; accepted 15 July 2003 The photoconductivity of films of single-wall carbon nanotubes has been of single-wall carbon nanotubes SWNTs is asso- ciated with both the nanotube's well-defined one- dimensional

Euler, William B.

441

Ab initio study of toroidal carbon nanotubes with encapsulated atomic metal loops  

NASA Astrophysics Data System (ADS)

Toroidal carbon nanotubes can serve as hosts for encapsulated loops of atomic metal wires. Such composite structures have been analyzed using density functional theory for a semiconducting C120 torus encapsulating chains of Fe, Au, and Cu atoms. The sheathed metal necklaces form a zigzag structure and drop the highest occupied molecular orbital and/or lowest unoccupied molecular orbital band gap to less than 0.1eV . The iron composite is ferromagnetic with a magnetic moment essentially the same as that of bcc iron. The azimuthal symmetry of these toroidal composites suggests that they may offer novel electromagnetic properties not associated with straight, metal-encapsulated carbon nanotubes.

Lusk, Mark T.; Hamm, Nathaniel

2007-09-01

442

The role of ?-iron nanoparticulates in the growth of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (˜200nm diameter) are grown by chemical vapor deposition using catalytic iron particles. Mössbauer spectroscopy enables differentiation among relatively large Fe3C, ?-Fe, and nanosized superparamagnetic fcc ?-Fe particles. The antiferromagnetic configuration of ?-Fe nanoparticles yields a significant fraction of uncompensated spins, producing a weak ferromagnetism that allows estimation of size (2-3nm ) via magnetization in zero field versus variable field cooling. This property of ?-Fe nanoparticles has not been previously employed. We propose that the surfaces of 200nm iron carbide particles are covered with nanosized ?-Fe and graphitized carbon that participate in the catalytic growth of nanotubes.

Khasanov, Airat; He, Jian; Gaillard, Jay; Yang, Keqin; Rao, Apparao M.; Cameron, C. Michelle; Schmeltzer, J. M.; Stevens, John G.; Nath, Amar

2008-07-01

443

Stabilization and carbonization of gel spun polyacrylonitrile\\/single wall carbon nanotube composite fibers  

Microsoft Academic Search

Gel spun polyacrylonitrile (PAN) and PAN\\/single wall carbon nanotube (SWNT) composite fibers have been stabilized in air and subsequently carbonized in argon at 1100°C. Differential scanning calorimetry (DSC) and infrared spectroscopy suggests that the presence of single wall carbon nanotube affects PAN stabilization. Carbonized PAN\\/SWNT fibers exhibited 10–30nm diameter fibrils embedded in brittle carbon matrix, while the control PAN carbonized

Han Gi Chae; Marilyn L. Minus; Asif Rasheed; Satish Kumar

2007-01-01

444

Size effects of carbon nanotubes and graphene on cellular uptake  

NASA Astrophysics Data System (ADS)

A quantitative thermodynamic model has been presented to investigate the effects of the size of carbon nanotubes and graphene on endocytosis, which provides a simple method to evaluate the optimal size with the fast endocytosis speed. It is found that the optimal radius of a close-ended nanotube increases from 12 nm to 25 nm by reducing its length to zero. However, an open-ended carbon nanotube has a larger optimal size than that of a close-ended nanotube. Furthermore, theoretical results show that a disk-shaped graphene has an optimal radius of about 25-100 nm when its thickness decreases from 20 nm to 5 nm. The agreement between theoretical results and experimental observations implies that the developed model could be applicable to understand the basic physical mechanism of endocytosis of carbon nanotubes and graphene.

Li, Xinlei

2012-11-01

445

Resistance-based biosensor of Multi-Walled Carbon Nanotubes.  

PubMed

Multi-Walled Carbon Nanotubes (MWNTs) are a good choice for resistive biosensors due to their great resistance changes when immunoreactions take place, they are also low-cost, more biocompatible than single-walled carbon nanotubes, and resistive measurement equipment is usually not expensive and readily available. In this work a novel resistive biosensor based on the immobilization of an antigen through a silanization process over the surface of Multi-Walled Carbon Nanotubes (MWNTs) is reported. Results show that the biosensor increases its conductivity when adding the antigen and decreases when adding the antibody making them good candidates for disease diagnosis. PMID:24689811

Kolosovas-Machuca, E S; Vera-Reveles, G; Rodríguez-Aranda, M C; Ortiz-Dosal, L C; Segura-Cardenas, Emmanuel; Gonzalez, Francisco J

2015-01-01

446

Applications of Carbon Nanotubes in Biotechnology and Biomedicine  

PubMed Central

Due to their electrical, chemical, mechanical and thermal properties, carbon nanotubes are one of the most promising materials for the electronics, computer and aerospace industries. Here, we discuss their properties in the context of future applications in biotechnology and biomedicine. The purification and chemical modification of carbon nanotubes with organic, polymeric and biological molecules are discussed. Additionally we review their uses in biosensors, assembly of structures and devices, scanning probe microscopy and as substrates for neuronal growth. We note that additional toxicity studies of carbon nanotubes are necessary so that exposure guidelines and safety regulations can be established in a timely manner. PMID:19763242

Bekyarova, Elena; Ni, Yingchun; Malarkey, Erik B.; Montana, Vedrana; McWilliams, Jared L.; Haddon, Robert C.; Parpura, Vladimir

2009-01-01

447

Van der Waals interaction between two crossed carbon nanotubes.  

PubMed

The analytical expressions for the van der Waals potential energy and force between two crossed carbon nanotubes are presented. The Lennard-Jones potential between pairs of carbon atoms and the smeared-out approximation suggested by L. A. Girifalco (J. Phys. Chem. 1992, 96, 858) were used. The exact formula is expressed in terms of rational and elliptical functions. The potential and force for carbon nanotubes were calculated. The uniform potential curves for single- and multiwall nanotubes were plotted. The equilibrium distance, maximal attractive force, and potential energy have been evaluated. PMID:20863127

Zhbanov, Alexander I; Pogorelov, Evgeny G; Chang, Yia-Chung

2010-10-26

448

Carbon Nanotubes Potentialities in Directional Dark Matter Searches  

E-print Network

We propose a new solution to the problem of dark matter directional detection based on large parallel arrays of carbon nanotubes. The phenomenon of ion channeling in single wall nanotubes is simulated to calculate the expected number of recoiling carbon ions, due to the hypothetical scattering with dark matter particles, subsequently being driven along their longitudinal extension. As shown by explicit calculation, the relative orientation of the carbon nanotube array with respect to the direction of motion of the Sun has an appreciable effect on the channeling probability of the struck ion and this provides the required detector anisotropic response.

L. M. Capparelli; G. Cavoto; D. Mazzilli; A. D. Polosa

2014-12-28

449

Synthesis of carbon nanotubes with and without catalyst particles  

PubMed Central

The initial development of carbon nanotube synthesis revolved heavily around the use of 3d valence transition metals such as Fe, Ni, and Co. More recently, noble metals (e.g. Au) and poor metals (e.g. In, Pb) have been shown to also yield carbon nanotubes. In addition, various ceramics and semiconductors can serve as catalytic particles suitable for tube formation and in some cases hybrid metal/metal oxide systems are possible. All-carbon systems for carbon nanotube growth without any catalytic particles have also been demonstrated. These different growth systems are briefly examined in this article and serve to highlight the breadth of avenues available for carbon nanotube synthesis. PMID:21711812

2011-01-01

450

Paper-based ultracapacitors with carbon nanotubes-graphene composites  

NASA Astrophysics Data System (ADS)

In this paper, a paper-based ultracapacitors were fabricated by the rod-rolling method with the ink of carbon nanomaterials, which were synthesized by arc discharge under various magnetic conditions. Composites of carbon nanostructures, including high-purity single-walled carbon nanotubes (SWCNTs) and graphene flakes were synthesized simultaneously in a magnetically enhanced arc. These two nanostructures have promising electrical properties and synergistic effects in the application of ultracapacitors. Scanning electron microscope, transmission electron microscope, and Raman spectroscopy were employed to characterize the properties of carbon nanostructures and their thin films. The sheet resistance of the SWCNT and composite thin films was also evaluated by four-point probe from room temperature to the cryogenic temperature as low as 90 K. In addition, measurements of cyclic voltammetery and galvanostatic charging/discharging showed the ultracapacitor based on composites possessed a superior specific capacitance of up to 100 F/g, which is around three times higher than the ultracapacitor entirely fabricated with SWCNT.

Li, Jian; Cheng, Xiaoqian; Sun, Jianwei; Brand, Cameron; Shashurin, Alexey; Reeves, Mark; Keidar, Michael

2014-04-01

451

Paper-based ultracapacitors with carbon nanotubes-graphene composites  

SciTech Connect

In this paper, a paper-based ultracapacitors were fabricated by the rod-rolling method with the ink of carbon nanomaterials, which were synthesized by arc discharge under various magnetic conditions. Composites of carbon nanostructures, including high-purity single-walled carbon nanotubes (SWCNTs) and graphene flakes were synthesized simultaneously in a magnetically enhanced arc. These two nanostructures have promising electrical properties and synergistic effects in the application of ultracapacitors. Scanning electron microscope, transmission electron microscope, and Raman spectroscopy were employed to characterize the properties of carbon nanostructures and their thin films. The sheet resistance of the SWCNT and composite thin films was also evaluated by four-point probe from room temperature to the cryogenic temperature as low as 90?K. In addition, measurements of cyclic voltammetery and galvanostatic charging/discharging showed the ultracapacitor based on composites possessed a superior specific capacitance of up to 100?F/g, which is around three times higher than the ultracapacitor entirely fabricated with SWCNT.

Li, Jian, E-mail: lijian@gwu.edu, E-mail: keidar@gwu.edu; Cheng, Xiaoqian; Brand, Cameron; Shashurin, Alexey; Keidar, Michael, E-mail: lijian@gwu.edu, E-mail: keidar@gwu.edu [Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC 20052 (United States); Sun, Jianwei; Reeves, Mark [Department of Physics, The George Washington University, Washington, DC 20052 (United States)

2014-04-28

452

Carbon Nanotube Radio-Frequency Single-Electron Transistor  

Microsoft Academic Search

We discuss the theory of the radio-frequency single-electron transistor and the measurements that use multiwalled carbon nanotubes as active elements. Our devices made of plasma-enhanced chemical-vapor-deposition nanotubes yield charge sensitivities of 10-20 ?e\\/\\u000a

Leif Roschier; Mika Sillanpää; Wang Taihong; Markus Ahlskog; Sumio Iijima; Pertti Hakonen

2004-01-01

453

Radio frequency analog electronics based on carbon nanotube transistors  

E-print Network

Radio frequency analog electronics based on carbon nanotube transistors Coskun Kocabas*, Hoon band with power gains as high as 14 dB. As a demon- stration, we fabricated nanotube transistor radios technologies. The invention of the transistor in 1947 represents the birth of the solid state electronics age

Rogers, John A.

454

A Computational Experiment on Single-Walled Carbon Nanotubes  

ERIC Educational Resources Information Center

A computational experiment that investigates single-walled carbon nanotubes (SWNTs) has been developed and employed in an upper-level undergraduate physical chemistry laboratory course. Computations were carried out to determine the electronic structure, radial breathing modes, and the influence of the nanotube's diameter on the…

Simpson, Scott; Lonie, David C.; Chen, Jiechen; Zurek, Eva

2013-01-01

455

Current Saturation and Electrical Breakdown in Multiwalled Carbon Nanotubes  

Microsoft Academic Search

We investigate the limits of high energy transport in multiwalled carbon nanotubes (MWNTs). In contrast to metal wires, MWNTs do not fail in the continuous, accelerating manner typical of electromigration. Instead, they fail via a series of sharp, equally sized current steps. We assign these steps to the sequential destruction of individual nanotube shells, consistent with the MWNT's concentric-shell geometry.

Philip G. Collins; M. Hersam; M. Arnold; R. Martel; Ph. Avouris

2001-01-01

456

Assembly of nanodevices with carbon nanotubes through nanorobotic manipulations  

Microsoft Academic Search

Properties and potential applications of carbon nanotubes are summarized by emphasizing the aspects of nanoelectronics and nanoelectromechanical systems (NEMS). The main technologies for the assembly of nanodevices through nanomanipulations with scanning probe microscopes and nanorobotic manipulators are overviewed, focusing on that of nanotubes. Key techniques for nanoassembly include the preparation of nano building blocks and property characterization of them, the

TOSHIO FUKUDA; FUMIHITO ARAI; Lixin Dong

2003-01-01

457

Carbon nanotubes might improve neuronal performance by favouring electrical shortcuts  

Microsoft Academic Search

Carbon nanotubes have been applied in several areas of nerve tissue engineering to probe and augment cell behaviour, to label and track subcellular components, and to study the growth and organization of neural networks. Recent reports show that nanotubes can sustain and promote neuronal electrical activity in networks of cultured cells, but the ways in which they affect cellular function

Giada Cellot; Emanuele Cilia; Sara Cipollone; Vladimir Rancic; Antonella Sucapane; Silvia Giordani; Luca Gambazzi; Henry Markram; Micaela Grandolfo; Denis Scaini; Fabrizio Gelain; Loredana Casalis; Maurizio Prato; Michele Giugliano; Laura Ballerini

2009-01-01

458

Synthesis and characterization of next-generation multifunctional material architectures : aligned carbon nanotube carbon matrix nanocomposites  

E-print Network

Materials comprising carbon nanotube (CNT) aligned nanowire (NW) polymer nanocomposites (A-PNCs) have emerged as promising architectures for next-generation multifunctional applications. Enhanced operating regimes, such ...

Stein, Itai Y

2013-01-01

459

Hierarchical carbon fiber composites with radially aligned carbon nanotubes : preservation of in-plane tensile properties  

E-print Network

Hierarchical carbon-nanotube (CNT)-based composites have significant potential to expand the performance and functionality of aerospace composite structures. Notably, circumferentially aligned CNT arrays have previously ...

Li, Richard, S.M. Massachusetts Institute of Technology

2013-01-01

460

Synthesis, assembly, and applications of single-walled carbon nanotube  

NASA Astrophysics Data System (ADS)

This dissertation presents the synthesis and assembly of aligned carbon nanotubes, and their applications in both nano-electronics such as transistor and integrated circuits and macro-electronics in energy conversion devices as transparent conducting electrodes. Also, the high performance chemical sensor using metal oxide nanowire has been demonstrated. Chapter 1 presents a brief introduction of carbon nanotube, followed by discussion of a new synthesis technique using nanosphere lithography to grow highly aligned single-walled carbon nanotubes atop quartz and sapphire substrates. This method offers great potential to produce carbon nanotube arrays with simultaneous control over the nanotube orientation, position, density, diameter and even chirality. Chapter 3 introduces the wafer-scale integration and assembly of aligned carbon nanotubes, including full-wafer scale synthesis and transfer of massively aligned carbon nanotube arrays, and nanotube device fabrication on 4 inch Si/SiO2 wafer to yield submicron channel transistors with high on-current density ˜ 20 muA/mum and good on/off ratio and CMOS integrated circuits. In addition, various chemical doping methods for n-type nanotube transistors are studied to fabricate CMOS integrated nanotube circuits such as inverter, NAND and NOR logic devices. Furthermore, defect-tolerant circuit design for NAND and NOR is proposed and demonstrated to guarantee the correct operation of logic circuit, regardless of the presence of mis-aligned or mis-positioned nanotubes. Carbon nanotube flexible electronics and smart textiles for ubiquitous computing and sensing are demonstrated in chapter 4. A facile transfer printing technique has been introduced to transfer massively aligned single-walled carbon nanotubes from the original sapphire/quartz substrates to virtually any other substrates, including glass, silicon, polymer sheets, and even fabrics. The characterization of transferred nanotubes reveals that the transferred nanotubes are highly conductive, transparent, and flexible as well. Based on transferred nanotube arrays on fabric, we have successfully demonstrated nanotube transistors with on/off ratios ˜ 105, and chemical sensors for low-concentration NO2 and 2,4,6-trinitrotoluene (TNT). In Chapter 5, I present the study of transparent conductive thin films made with two kinds of commercial carbon nanotubes: HiPCO and arc-discharge nanotubes. These films have been further exploited as hole-injection electrodes for organic light emitting diodes (OLEDs) on both rigid glass and flexible substrates. Our experiments reveal that films based on arc discharge nanotubes are overwhelmingly better than HiPCO-nanotube-based films in all the critical aspects, including the surface roughness, sheet resistance, and transparency. The optimized films show a typical sheet resistance of ˜160O/? at 87% transparency and have been successfully used to make OLEDs with high stability and long lifetime. Lastly, I present the fast and scalable integration of nanowire chemical sensors with micromachined hotplates built on SiN membranes. These hotplates allowed nanowire chemical sensors to operate at elevated temperatures in order to enhance the sensitivity of chemical sensors to target gases. By applying different current through the platinum heating filament, we can easily vary the device temperature from room temperature to 350°C. These nanosensors with integrated hot plates have been exploited for the detection of ethanol, CO and hydrogen down to concentrations of 1 ppm, 10 ppm and 50 ppm, respectively.

Ryu, Koungmin