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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

Estimation of Magnetic Susceptibility Anisotropy of Carbon Nanotubes Using  

E-print Network

excitation (PLE) spectrum of such samples showed peaks assigned20 to specific nano- tube species (chiralitiesEstimation of Magnetic Susceptibility Anisotropy of Carbon Nanotubes Using Magnetophotoluminescence a magnetophotoluminescence excitation spectroscopy study on micelle-suspended single-walled carbon nanotubes in high magnetic

Kono, Junichiro

3

Magnetically Controlled Terahertz Absorption and Emission in Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

We show that an experimentally attainable magnetic field applied along the axis of a metallic carbon nanotube not only opens the gap in the nanotube energy spectrum but also allows optical transitions, which are forbidden in the absence of the field. Possible terahertz applications of this effect are discussed.

Portnoi, M. E.; Rosenau da Costa, M.; Kibis, O. V.; Shelykh, I. A.

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

Electric and Magnetic Properties of Co-filled Carbon Nanotube  

NASA Astrophysics Data System (ADS)

We investigate the electric and magnetic properties of a (3,3) single-walled carbon nanotube filled with a linear Co nanowire. We carry out first-principle calculations based on the spin-polarized density functional theory, and find that in the stable structure, it shows half metallic ferromagnetic behavior, i.e., the majority-spin electrons show metallic behavior while the minority-spin electrons have a semiconducting bandgap.

Rahman, Md. Mahmudur; Kisaku, Masanori; Kishi, Tomoya; Roman, Tanglaw Abat; Diño, Wilson Agerico; Nakanishi, Hiroshi; Kasai, Hideaki

2005-02-01

6

Magnetic properties of multi-walled carbon nanotubes encapsulated  

Microsoft Academic Search

The experimental apparatus by self-designed was used, Fe\\/Co particles encapsulated in multi-walled carbon nanotubes (MWCNTs) were prepared by the method of anodic arc discharging plasma. The products were characterized by transmission election microscopy, Raman spectroscopy and X-ray diffractometry. The magnetic properties of the products were characterized with vibration sample magnetometer. The TEM results show that MWCNTs have little impurity and

LI Wei-xue

7

Magnetic response of single-walled carbon nanotubes induced by an external magnetic field.  

PubMed

Using first-principles density functional calculations, magnetically induced currents are obtained for zigzag single-walled carbon nanotubes. Clear differences and trends in current flow are observed between the different nanotube families. In particular, for a magnetic field applied along the tube axis, the current response of the ? = 0 infinite nanotubes is paramagnetic, whereas for ? = 1 and 2 nanotubes, the response is diamagnetic. The results are used to predict and interpret the significant changes in NMR properties for small molecules encapsulated inside a tube. PMID:21171576

Kibalchenko, Mikhail; Payne, Mike C; Yates, Jonathan R

2011-01-25

8

Carbon nanotube decorated magnetic microspheres as an affinity matrix for biomolecules  

E-print Network

disciplines ranging from materials science to medicine. As allotropes of carbon with a cylindricalCarbon nanotube decorated magnetic microspheres as an affinity matrix for biomolecules Hayriye ¨Unal and Javed H. Niazi* Carbon nanotube (CNT) decorated magnetic microspheres were fabricated

Yanikoglu, Berrin

9

Sensitive magnetic force detection with a carbon nanotube resonator  

NASA Astrophysics Data System (ADS)

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; Haapamaki, Chris; Baugh, Jonathan

2014-03-01

10

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

11

Enhancement of thermal and electrical properties of carbon nanotube polymer composites by magnetic field processing  

E-print Network

SWNT composites. Presently, the thermal conductivity for an isolated multiwall carbon nano- tubes MWNTsEnhancement of thermal and electrical properties of carbon nanotube polymer composites by magnetic and electrical properties of single wall carbon nanotube CNT -polymer composites are significantly enhanced

Garmestani, Hamid

12

Interband Magneto-Optics in Carbon Nanotubes in Pulsed High Magnetic Fields  

Microsoft Academic Search

To extend our earlier work ootnotetextS. Zaric et al., Science 304, 1129 (2004). on the Aharonov-Bohm effect in carbon nanotubes to higher fields, we have performed interband magneto-absorption and magneto-photoluminescence experiments in micelle-suspended single-walled carbon nanotubes in pulsed high magnetic fields up to 71 T. Because of their anisotropic magnetic susceptibilities, the nanotubes dynamically align in response to the pulsed

S. Zaric; O. Portugall; S. A. Crooker; X. Wei; H. U. Mueller; V. C. Moore

2005-01-01

13

Synthesis of magnetic carbon nanotube and photocatalytic dye degradation ability.  

PubMed

In this paper, magnetic carbon nanotube (M-CNT) was synthesized. The photocatalytic dye degradation ability of M-CNT in the presence of hydrogen peroxide (H2O2) from colored wastewater was studied. Manganese ferrite (MnFe2O4) was synthesized in the presence of multiwalled carbon nanotube. Direct Red 23 (DR23), Direct Red 31 (DR31), and Direct Red 81 (DR81) were used as anionic dyes. The characteristics of M-CNT were investigated using Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). The photocatalytic dye degradation using M-CNT was studied by UV-vis spectrophotometer and ion chromatography (IC). The effects of M-CNT dosage, initial dye concentration, and salt on the degradation of dye were evaluated. Formate, acetate, and oxalate anions were detected as dominant aliphatic intermediates. Inorganic anions (nitrate and sulfate anions) were detected and quantified as the mineralization products of dyes during the degradation process. The results indicated that the M-CNT could be used as a magnetic catalyst to degrade anionic dyes from colored wastewater. PMID:24838801

Mahmoodi, Niyaz Mohammad

2014-09-01

14

Carbon Nanotubes.  

E-print Network

?? Carbon nanotubes have extraordinary mechanical, electrical, thermal andoptical properties. They are harder than diamond yet exible, have betterelectrical conductor than copper, but can also… (more)

Fredriksson, Tore

2014-01-01

15

Functionalization of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes have unique properties that make them attractive for different engineering applications. However, because of their chemical inertness, carbon nanotubes have to be functionalized in order to acquire additional physico-chemical properties. Large multiwalled carbon nanotubes are different from fullerenes and singlewalled nanotubes because the stresses in their walls are almost relaxed while most chemical methods for fullerene functionalization exploit this effect of stressed bonds. The objective of this work is to develop new methods for functionalization of multiwalled carbon nanotubes. This work is dedicated to study two functionalization methods. The first deals with physico-chemical functionalization by filling the nanotube interior with colloidal suspensions. Irreversible adsorption of functional nanoparticles on the nanotube wall leads to the nanotube functionalization. The second method is purely chemical functionalization, which uses the reaction of cyclopropanation to break pi-bonds in the benzene rings of the nanotubes with formation of new ?-bonds with deprotonated malonate. This so-called Bingel reaction has been used in fullerene chemistry and in this work was applied for the first time to functionalize multiwalled carbon nanotubes. While capillary filling of carbon nanotubes was known long ago, the research community was skeptical about possibility of engulfing nanoparticles into nanotubes by capillary forces. We developed and implemented capillary method to fill nanotubes with different nanoparticles. Using this method, magnetic carbon nanotubes were produced for the first time. Synthesized nanotubes have very high magnetic moment and allow to manipulate them by magnetic field. These magnetic nanotubes have been successfully used in fabrication of carbon nanotube-tipped pipettes for biological probes. The Bingel reaction was studied on three sets of multiwalled carbon nanotubes with diameters: 20nm, 100nm, and 300nm. To estimate the degree of Bingel functionalization, the chemical tagging of gold nanoparticles to the malonated nanotubes was used. Gold was attached using the sulfur-gold bridges formed after the reaction of transesterification of malonated tubes with 2(methylthio)ethanol. We found that the critical size for Bingel reaction to occur along the whole nanotube wall is less than 200 nm. Larger nanotubes could be also Bingel modified, but their chemical activity is mostly observed at the nanotube ends.

Korneva, Guzeliya

16

Electrostatic waves in carbon nanotubes with an axial magnetic field  

SciTech Connect

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 [Department of Physics, Malayer University, Malayer 65719-95863 (Iran, Islamic Republic of)] [Department of Physics, Malayer University, Malayer 65719-95863 (Iran, Islamic Republic of); Bagheri, Mehran [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)

2013-10-15

17

Structural anisotropy of magnetically aligned single wall carbon nanotube films  

SciTech Connect

Thick films of aligned single wall carbon nanotubes and ropes have been produced by filtration/deposition from suspension in strong magnetic fields. We measured mosaic distributions of rope orientations in the film plane, for samples of different thicknesses. For an {approx}1 {mu}m film the full width at half maximum (FWHM) derived from electron diffraction is 25 degree sign -28 degree sign . The FWHM of a thicker film ({approx}7 {mu}m) measured by x-ray diffraction is slightly broader, 35{+-}3 degree sign . Aligned films are denser than ordinary filter-deposited ones, and much denser than as-grown material. Optimization of the process is expected to yield smaller FWHMs and higher densities. (c) 2000 American Institute of Physics.

Smith, B. W. [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)] [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Benes, Z. [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)] [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Luzzi, D. E. [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)] [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Fischer, J. E. [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)] [Department of Materials Science and Engineering and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Walters, D. A. [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States)] [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States); Casavant, M. J. [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States)] [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States); Schmidt, J. [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States)] [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States); Smalley, R. E. [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States)] [Center for Nanoscale Science and Technology, Rice University, Houston, Texas 77259 (United States)

2000-07-31

18

Magnetic Properties of Fe Nanowire in the Carbon Nanotubes on Ni(111)  

NASA Astrophysics Data System (ADS)

We have investigated the magnetic properties of Fe-filled carbon nanotubes (CNT) on Ni(111), based on the density functional theory. Fe-filled carbon nanotubes (CNT) on Ni(111) exhibit spin-polarization when the Fe wire adheres contrary to the Ni surface side. Fe wire has no spin-polarization when the Fe wire adheres adjacent to the Ni surface side. The bonding states between Ni and C atoms affect the magnetic properties of Fe wire.

Kisaku, Masanori; Kishi, Tomoya; Matsunaka, Daisuke; Diño, Wilson Agerico; Rahman, M. M.; Nakanishi, Hiroshi; Kasai, Hideaki

19

Magnetic solid-phase extraction based on magnetic carbon nanotube for the determination of estrogens in milk.  

PubMed

In this work, a novel method for the fabrication of magnetic carbon nanotubes based on 'aggregation wrap' was proposed. When carbon nanotubes and magnetic nanoparticles were vortically mixed in a solvent, the magnetic nanoparticles were wrapped into the carbon nanotube bundles that formed during the aggregation process, leading to the formation of magnetic carbon nanotubes. Thus, the resultant material can be separated from the solvent rapidly and conveniently by a magnet. Our investigation demonstrated that the 'aggregation wrap' mechanism for the preparation of magnetic composite is also applicable to other self-aggregated micro/nanomaterials, including graphene, graphite, C(60), etc. To testify the feasibility of the magnetic composites in sample preparation, the resultant magnetic carbon nanotubes were applied as sorbents for magnetic solid-phase extraction (MSPE) of estrogens in milk samples. Under optimized conditions, a rapid, convenient and efficient method for the determination of estrogens in milk samples was established by the combination of MSPE with high-performance liquid chromatography with fluorescence detector. The linearity range of the proposed method was 5-2000 ?g/L with correlation coefficients (R) of 0.9983-0.9994. The limit of detection (LOD) for three estrogens ranged from 1.21 to 2.35 ?g/L. The intra- and inter-day relative standard deviations (RSDs) were <9.3%. The reproducibility of the MSPE with different batches of magnetic carbon nanotubes was acceptable with RSD values <3.6%. PMID:21780288

Ding, Jun; Gao, Qiang; Li, Xiao-Shui; Huang, Wei; Shi, Zhi-Guo; Feng, Yu-Qi

2011-09-01

20

Magnetic field enhanced thermal conductivity in heat transfer nanofluids containing Ni coated single wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

In this paper, we report that the thermal conductivity (TC) of heat transfer nanofluids containing Ni coated single wall carbon nanotube can be enhanced by applied magnetic field. A reasonable explanation for these interesting results is that Ni coated nanotubes form aligned chains under applied magnetic field, which improves thermal conductivity via increased contacts. On longer holding in magnetic field, the nanotubes gradually move and form large clumps of nanotubes, which eventually decreases the TC. When we reduce the magnetic field strength and maintain a smaller field right after TC reaches the maximum, the TC value can be kept longer compared to without magnetic field. We attribute gradual magnetic clumping to the gradual cause of the TC decrease in the magnetic field. We also found that the time to reach the maximum peak value of TC is increased as the applied magnetic field is reduced. Scanning electron microscopy images show that the Ni coated nantubes are aligned well under the influence of a magnetic field. Transmission electron microscopy images indicate that nickel remains attached onto the nanotubes after the magnetic field exposure.

Wright, Brian; Thomas, Dustin; Hong, Haiping; Groven, Lori; Puszynski, Jan; Duke, Edward; Ye, Xiangrong; Jin, Sungho

2007-10-01

21

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

22

Diameter Dependent Magnetic and Electronic Properties of Single-Walled Carbon Nanotubes with Fe Nanowires  

NASA Astrophysics Data System (ADS)

We investigate the electronic and magnetic properties of single-walled carbon nanotubes (SWNTs) filled with Fe nanowires, based on the spin-polarized density functional theory. We find that in the stable structure, the Fe-filled (3,3) and (5,0) SWNTs exhibit semiconducting properties, and the magnetic moment of Fe nanowires inside disappears. On the other hand, the Fe-filled (4,4), (5,5), (6,6) and (6,0) SWNTs, having larger radii, are metallic and exhibit ferromagnetic properties. The corresponding magnetic moment increases with increasing nanotube diameter.

Kisaku, Masanori; Rahman, MD. Mahmudur; Kishi, Tomoya; Matsunaka, Daisuke; Roman, Tanglaw Abat; Diño, Wilson Agerico; Nakanishi, Hiroshi; Kasai, Hideaki

2005-02-01

23

Magnetic Brightening of Dark Excitons in Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

To gain insight into the internal energy structure and radiative properties of excitons in single-walled carbon nanotubes (SWNTs), we have studied photoluminescence (PL) from individualized HiPco and CoMoCAT samples as a function of magnetic field (B) and temperature (T). The PL intensity increased, or ``brightened,'' with B applied along the tube axis and the amount of brightening increased with decreasing T. These results are consistent with the existence of a dark state below the first bright state [1]. In the presence of time reversal symmetry, exchange-interaction-induced mixing between excitons in two equivalent valleys (the K and K' valleys) is expected to result in a set of exciton states, only one of which is optically active. This predicted bright state, however, is not the lowest in energy. Excitons would be trapped in the dark, lowest-energy state without a radiative recombination path. When a tube-threading B is applied, addition of an Aharonov-Bohm phase modifies the circumferential boundary conditions on the wave functions and lifts time reversal symmetry [2,3]. This symmetry breaking splits the K and K' valley transitions, lessening the intervalley mixing and causing the recovery of the unmixed direct K and K' excitons, which are both optically active. We have calculated PL spectra through B-dependent effective masses, populations of finite-k states, and acoustic phonon scattering, which quantitatively agree with the observations. These results demonstrate the existence of dark excitons, their influence on the PL quantum yield, and their elimination through symmetry manipulation by a B. This work was performed in collaboration with J. Shaver, S. Zaric, O. Portugall, V. Krstic, G. L. J. A. Rikken, X. Wei, S. A. Crooker, Y. Miyauchi, S. Maruyama, and V. Perebeinos and supported by the Robert A. Welch Foundation, the NSF, and EuroMagNET. [1] V. Perebeinos et al., Phys. Rev. Lett. 92, 257402 (2004); H. Zhao and S. Mazumdar, Phys. Rev. Lett. 93, 157402 (2004); V. Perebeinos et al., Nano Lett. 5, 2495 (2005); C. D. Spataru et al., Phys. Rev. Lett. 95, 247402 (2005). [2] T. Ando, J. Phys. Soc. Jpn. 75, 024707 (2006). [3] S. Zaric et al., Science 304, 1129 (2004); Phys. Rev. Lett. 96, 016406 (2006).

Kono, Junichiro

2007-03-01

24

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

25

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

NASA Astrophysics Data System (ADS)

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.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. Electronic supplementary information (ESI) available: Additional TEM image, DLS diagram, and FT-IR data. See DOI: 10.1039/c3nr00636k

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

2013-05-01

26

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

PubMed

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. PMID:25409786

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

2014-12-12

27

Carbon Nanotubes  

NSDL National Science Digital Library

From the NanoEd Resource Portal, this course describes the purpose and uses of carbon nanotubes in etching, indentation, compression, bending, and twisting as well as their application as gears. Instructed by Dr. Meyya Meyyappan and contributed by the NASA Ames Research Center, the main content of this course is the variety of demonstration videos on each topic so visitors may make the nanoscale visible. In total, there are thirty mpg format videos, and each would make an excellent addition to any nanotechnology classroom.

Meyyappan, Meyya

2012-04-12

28

Tuning electronic transport in cobalt-filled carbon nanotubes using magnetic fields.  

PubMed

Metal-filled and decorated carbon nanotubes represent a class of quasi one-dimensional hybrid systems with enormous potential for applications in nanoelectronics and spintronics. Here we show that is possible to control the electrical conduction in ferromagnetic metal-filled carbon nanotubes by means of external magnetic fields, suggesting specific dimensionality-dependent conduction regimes. By increasing the magnetic field, we drive the charge flow from a positive to a negative magneto-conductance, revealing channel-selective conduction. Furthermore, the zero-field current temperature dependence shows different regimes, suggesting that the inter-shell hopping, assisted by the cobalt clusters, plays a key role in the dimensional crossover. The possibility of engineering and controlling the nature and size of the conducting shells and the filling with magnetic materials can allow the implementation of these systems in tunable hybrid nano-sensors and multifunctional magnetic devices. PMID:24257837

Rossella, Francesco; Soldano, Caterina; Onorato, Pasquale; Bellani, Vittorio

2014-01-21

29

High-Resolution Magnetic Resonance Force Microscopy using Iron Filled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Magnetic Resonance Force Microscopy is able to probe below surfaces to map out spins in a non-destructive manner by measuring the force from the dipolar coupling of a magnetic probe to spins in the sample. We have used low force constant cantilevers with low intrinsic dissipation to obtain 2 spin sensitivity. To obtain better sensitivity one avenue of improvement is to increase the magnetic field gradient from the magnetic probe. Iron-filled carbon nanotubes provide a promising route for very high magnetic field gradient micromagnetic probes; we have successfully attached these iron nanowires to IBM style ultrasoft silicon cantilevers. The smaller size of the tip (15 to 25 nm) allows gradients an order of magnitude greater than micron-sized rare-earth magnets. In addition, iron filled carbon nanotubes have the possibility to lower the non-contact friction by reducing the surface area of the probe close to the sample. Iron filled carbon nanotubes also exhibit high anisotropy fields, a result of the shape anisotropy. This work was supported by The Army Research Office under W911NF-07-1-0305 and the National Science Foundation under DMR-0807093.

Herman, Michael; Banerjee, Palash; Chung Fong, Kin; Pelekhov, Denis; Wolny, Franziska; Muhl, Thomas; Büchner, Bernd; Hammel, Chris

2009-03-01

30

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

31

Magnetic CoFe2O4/carbon nanotubes composites: fabrication, microstructure and magnetic response  

NASA Astrophysics Data System (ADS)

By combining the unique microstructure of carbon nanotubes (CNTs) with the good magnetism of CoFe2O4 ferrites, CoFe2O4/CNTs nanocomposites were prepared by the solvothermal method for the application of targeting therapy and tumor hyperthermia. X-ray diffraction (XRD), thermal gravity analysis (TGA), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM) were introduced to study the influence of the solvothermal temperature, time and the CNTs content on the microstructure and magnetic properties of CoFe2O4/CNTs nanocomposites. The diameter of CoFe2O4 nanoparticles coating on the surface of CNTs and the saturation magnetization (Ms) increased with the solvothermal temperature. CoFe2O4/CNTs nanocomposites prepared at 180°C, 200°C and 220°C exhibited superparamagnetism at room temperature, while the samples prepared at 240°C and 260°C presented ferromagnetism. And the solvothermal time and CNTs content slightly affected the microstructure and magnetic properties, Ms and coercivity (Hc) increased slightly with the increasing solvothermal time and the decreasing CNTs content.

Wang, Panfeng; Xu, Jingcai; Han, Yanbing; Hong, Bo; Jin, Hongxiao; Jin, Dingfeng; Peng, Xiaoling; Li, Jing; Ge, Hongliang; Wang, Xinqing

2014-05-01

32

Optimization of Magnetic Field-Assisted Synthesis of Carbon Nanotubes for Sensing Applications  

PubMed Central

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

33

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

34

Metal-functionalized single-walled graphitic carbon nitride nanotubes: a first-principles study on magnetic property  

PubMed Central

The magnetic properties of metal-functionalized graphitic carbon nitride nanotubes were investigated based on first-principles calculations. The graphitic carbon nitride nanotube can be either ferromagnetic or antiferromagnetic by functionalizing with different metal atoms. The W- and Ti-functionalized nanotubes are ferromagnetic, which are attributed to carrier-mediated interactions because of the coupling between the spin-polarized d and p electrons and the formation of the impurity bands close to the band edges. However, Cr-, Mn-, Co-, and Ni-functionalized nanotubes are antiferromagnetic because of the anti-alignment of the magnetic moments between neighboring metal atoms. The functionalized nanotubes may be used in spintronics and hydrogen storage. PMID:21711614

2011-01-01

35

Iron filled carbon nanotubes as novel monopole-like sensors for quantitative magnetic force microscopy.  

PubMed

We present a novel ultrahigh stability sensor for quantitative magnetic force microscopy (MFM) based on an iron filled carbon nanotube. In contrast to the complex magnetic structure of conventional MFM probes, this sensor constitutes a nanomagnet with defined properties. The long iron nanowire can be regarded as an extended dipole of which only the monopole close to the sample surface is involved in the imaging process. We demonstrate its potential for high resolution imaging. Moreover, we present an easy routine to determine its monopole moment and prove that this calibration, unlike other approaches, is universally applicable. For the first time this enables straightforward quantitative MFM measurements. PMID:20876975

Wolny, F; Mühl, T; Weissker, U; Lipert, K; Schumann, J; Leonhardt, A; Büchner, B

2010-10-29

36

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

37

Heteronuclear carbon nanotubes  

NASA Astrophysics Data System (ADS)

The physical properties of double-wall carbon nanotubes (DWCNT) with highly 13C enriched inner walls were studied with Raman spectroscopy and nuclear magnetic resonance (NMR). An inhomogeneous broadening of the vibrational modes is explained by the random distribution of 12C and 13C nuclei based on ab-initio calculations. The growth of DWCNTs from natural and 13C enriched fullerene mixtures indicates that carbon does not diffuse freely along the tube axis during the inner tube growth. The high curvature of the small diameter inner tubes manifests in an increased distribution of the NMR chemical shift tensor components.

Simon, Ferenc; Pfeiffer, Rudolf; Kramberger, Christian; Kuzmany, Hans; Zólyomi, Viktor; Kürti, Jen?; Singer, Philip M.; Alloul, Henri

2005-09-01

38

The magnetic, relaxometric, and optical properties of gadolinium-catalyzed single walled carbon nanotubes  

PubMed Central

We report the magnetic behavior, relaxometry, phantom magnetic resonance imaging (MRI), and near-infrared (NIR) photoluminescence spectroscopy of gadolinium (Gd) catalyzed single-walled carbon nanotubes (Gd-SWCNTs). Gd-SWCNTs are paramagnetic with an effective magnetic moment of 7.29??B. Gd-SWCNT solutions show high r1 and r2 relaxivities at very low (0.01?MHz) to clinically relevant (61?MHz) magnetic fields (r1???130?mM?1?s?1, r2???160?mM?1?s?1). Analysis of nuclear magnetic resonance dispersion profiles using Solomon, Bloembergen, and Morgan equations suggests that multiple structural and dynamic parameters such as rotational correlation time ?R, rate of water exchange ?M, and the number of fast-exchanging water molecules within the inner sphere q may be responsible for the increase in r1 and r2 relaxivity. The T1 weighted MRI signal intensity (gradient echo sequence; repetition time (TR)?=?66?ms, echo time (TE)?=?3?ms, flop angle?=?108°) of Gd-SWCNT phantom solution is 14 times greater than the Gd-based clinical MRI contrast agent Magnevist. Additionally, these nanotubes exhibit near infrared fluorescence with distinct E11 transitions of several semiconducting SWCNTs. Taken together, these results demonstrate that Gd-SWCNTs have potential as a novel, highly efficacious, multimodal MRI-NIR optical imaging contrast agent. PMID:23653487

Sitharaman, Balaji; Jacobson, Barry D.; Wadghiri, Youssef Z.; Bryant, Henry; Frank, Joseph

2013-01-01

39

The magnetic, relaxometric, and optical properties of gadolinium-catalyzed single walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We report the magnetic behavior, relaxometry, phantom magnetic resonance imaging (MRI), and near-infrared (NIR) photoluminescence spectroscopy of gadolinium (Gd) catalyzed single-walled carbon nanotubes (Gd-SWCNTs). Gd-SWCNTs are paramagnetic with an effective magnetic moment of 7.29 ?B. Gd-SWCNT solutions show high r1 and r2 relaxivities at very low (0.01 MHz) to clinically relevant (61 MHz) magnetic fields (r1 ? 130 mM-1 s-1, r2 ? 160 mM-1 s-1). Analysis of nuclear magnetic resonance dispersion profiles using Solomon, Bloembergen, and Morgan equations suggests that multiple structural and dynamic parameters such as rotational correlation time ?R, rate of water exchange ?M, and the number of fast-exchanging water molecules within the inner sphere q may be responsible for the increase in r1 and r2 relaxivity. The T1 weighted MRI signal intensity (gradient echo sequence; repetition time (TR) = 66 ms, echo time (TE) = 3 ms, flop angle = 108°) of Gd-SWCNT phantom solution is 14 times greater than the Gd-based clinical MRI contrast agent Magnevist. Additionally, these nanotubes exhibit near infrared fluorescence with distinct E11 transitions of several semiconducting SWCNTs. Taken together, these results demonstrate that Gd-SWCNTs have potential as a novel, highly efficacious, multimodal MRI-NIR optical imaging contrast agent.

Sitharaman, Balaji; Jacobson, Barry D.; Wadghiri, Youssef Z.; Bryant, Henry; Frank, Joseph

2013-04-01

40

Orbital and spin magnetic moments of transforming one-dimensional iron inside metallic and semiconducting carbon nanotubes  

NASA Astrophysics Data System (ADS)

The orbital and spin magnetic properties of iron inside metallic and semiconducting carbon nanotubes are studied by means of local x-ray magnetic circular dichroism (XMCD) and bulk superconducting quantum interference device (SQUID). The iron-nanotube hybrids are initially ferrocene filled single-walled carbon nanotubes (SWCNT) of different metallicities. We show that the ferrocene's molecular orbitals interact differently with the SWCNT of different metallicities with no significant XMCD response. At elevated temperatures the ferrocene molecules react with each other to form cementite nanoclusters. The XMCD at various magnetic fields reveal that the orbital and/or spin magnetic moments of the encapsulated iron are altered drastically as the transformation to the 1D clusters takes place. The orbital and spin magnetic moments are both found to be larger in filled semiconducting nanotubes than in the metallic sample. This could mean that the magnetic polarization of the encapsulated material depends on the metallicity of the tubes. From a comparison between the iron 3d magnetic moments and the bulk magnetism measured by SQUID, we conclude that the delocalized magnetisms dominate the magnetic properties of these 1D hybrid nanostructures.

Briones-Leon, Antonio; Ayala, Paola; Liu, Xianjie; Yanagi, Kazuhiro; Weschke, Eugen; Eisterer, Michael; Jiang, Hua; Kataura, Hiromichi; Pichler, Thomas; Shiozawa, Hidetsugu

2013-05-01

41

Selective enrichment of phosphopeptides by titania nanoparticles coated magnetic carbon nanotubes.  

PubMed

Selective enrichment of phosphoproteins or phosphopeptides from complex mixtures is essential for mass spectrometry (MS)-based phosphoproteomics. In this work, for the first time, titania nanoparticles coated magnetic carbon nanotubes (denoted as MagCNTs@TiO? composites) were synthesized through a facile but effective solvothermal reaction for selective enrichment of phosphopeptides. The MagCNTs@TiO? material demonstrated low limit of detection (20 fmol), along with an exceptional great specificity to capture phosphopeptides from a tryptic digest of the mixture of a nonphosphorylated protein BSA and a phosphorylated protein ?-casein with molar ratios of BSA/?-casein up to 200:1. In addition, the high magnetic susceptibility allowed convenient separation of the target peptides by magnetic separation. Experimental results demonstrated that the MagCNTs@TiO? composites showed excellent potential for the selective enrichment of phosphopeptides for MS analysis. PMID:24274265

Yan, Yinghua; Zheng, Zhifang; Deng, Chunhui; Zhang, Xiangmin; Yang, Pengyuan

2014-01-01

42

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

43

Fabrication of Carbon Nanotubes  

Microsoft Academic Search

The remarkable properties of carbon nanotubes give promise of a diverse array of revolutionary technologies and applications. Synthesis remains the key to their development. This article will review many of the current methods used for nanotube synthesis and the recent results towards achieving the goal of large-scale production with rational control of nanotube structure and properties.

Christopher T. Kingston; Benoit Simard

2003-01-01

44

Naturally produced carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes represent an impressive kind of materials with diverse unexpected properties, and different methods to artificially produce them have been developed. Recently, they have also been synthesized at low temperatures, demonstrating that these materials might exist in fluids or carbon rocks of the Earth’s crust. A new type of natural encapsulated carbon nanotubes found in a coal–petroleum mix is

C. Velasco-Santos; A. L. Mart??nez-Hernández; A. Consultchi; R. Rodr??guez; V. M. Castaño

2003-01-01

45

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

46

Reinforced Carbon Nanotubes.  

DOEpatents

The present invention relates generally to reinforced carbon nanotubes, and more particularly to reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials. 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)

2005-06-28

47

Magnetization Study of Sulfur-doped Graphitic Nano-platelets and Single Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Recently we investigated the magnetic behavior of as-prepared and sulfur doped chemically exfoliated graphene nano-platelets (GNPs) and single walled carbon nanotubes (SWCNTs). The doping was achieved by annealing desired carbon nanostructures with 0, 1.0, 1.5 and 3 at% sulfur in an evacuated quartz tube at 1000 ^oC for 1 day, followed by multiple rinsing in alcohol and drying in vacuum to remove excess sulfur. The isothermal M vs. H as well as the temperature-dependent M vs. T measurements were obtained using a vibrating sample magnetometer. We found that sulfur doping drastically changes the magnetic behavior of the as-prepared samples (both SWCNTs and GNPs). The results of zero-field-cooling (ZFC) and field-cooling (FC) in M vs. T measurements indicated the existence of large amount of coupled super-paramagnetic domains, along with antiferromagnetic domains. The saturation magnetization decreased in S doped GNPs, while a contrasting trend was observed in S doped SWCNTs. The role of edge states and structural defects in carbon nanostructures in the observed magnetic properties will be discussed.

Zhu, J.; Oliveira, L.; Podila, R.; Neeleshwar, S.; Chen, Y. Y.; He, J.; Skove, M.; Rao, A. M.

2013-03-01

48

Determination of puerarin in rat plasma using PEGylated magnetic carbon nanotubes by high performance liquid chromatography.  

PubMed

This paper described a novel application of PEGylated magnetic carbon nanotubes as solid-phase extraction nanosorbents for the determination of puerarin in rat plasma by high performance liquid chromatography (HPLC). A solvothermal method was employed for the synthesis of monodisperse magnetites anchored onto multi-walled carbon nanotubes (MWCNTs@Fe3O4). In order to enhance the water solubility of MWCNTs@Fe3O4 that ensured sufficient contact between nanosorbents and analytes in the sampling procedure, the obtained nanomaterials were further noncovalently functionalized using a phospholipids-polyethylene glycol (DSPE-PEG). The PEGylated MWCNTs@Fe3O4 nanomaterials had an extremely large surface area and exhibit a strong interaction capability for puerarin with ?-? stacking interactions. The captured puerarin/nanosorbents were easily isolated from the plasma by placing a magnet, and desorbed by acetonitrile. The experimental variables affecting the extraction efficiency were investigated. The calibration curve of puerarin was linear from 0.01 to 20 ?g/ml, and the limit of detection was 0.005 ?g/ml. The precisions ranged from 2.7% to 3.5% for within-day measurement, and for between-day variation was in the range of 3.1-5.9%. The method recoveries were acquired from 95.2% to 98.0%. Moreover, the analytical performance obtained by PEGylated magnetic MWCNTs was also compared with that of magnetic MWCNTs. All results showed that our proposed method was an excellent alternative for the analysis of puerarin in rat plasma. PMID:24768919

Yu, Panfeng; Wang, Qi; Ma, Hongwei; Wu, Ji; Shen, Shun

2014-05-15

49

Superplastic carbon nanotubes  

Microsoft Academic Search

The theoretical maximum tensile strain - that is, elongation - of a single-walled carbon nanotube is almost 20%, but in practice only 6% is achieved. Here we show that, at high temperatures, individual single-walled carbon nanotubes can undergo superplastic deformation, becoming nearly 280% longer and 15 times narrower before breaking. This superplastic deformation is the result of the nucleation and

J. Y. Huang; S. Chen; Z. Q. Wang; K. Kempa; Y. M. Wang; S. H. Jo; G. Chen; M. S. Dresselhaus; Z. F. Ren

2006-01-01

50

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

51

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

52

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

53

Naturally produced carbon nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes represent an impressive kind of materials with diverse unexpected properties, and different methods to artificially produce them have been developed. Recently, they have also been synthesized at low temperatures, demonstrating that these materials might exist in fluids or carbon rocks of the Earth's crust. A new type of natural encapsulated carbon nanotubes found in a coal-petroleum mix is presented. These findings show that all allotropic carbon forms known up to date can be produced in Nature, where pressure, catalysts particles, shear stress and parameters other than exclusively very high temperature, seem to play an important role for producing nanotubes.

Velasco-Santos, C.; Martínez-Hernández, A. L.; Consultchi, A.; Rodríguez, R.; Castaño, V. M.

2003-05-01

54

Alignment of Single Wall Carbon Nanotubes Under High Magnetic Fields Utilizing a Self-Organizing of Epoxy Matrix  

NASA Astrophysics Data System (ADS)

In this investigation, we present studies of the alignment of single wall carbon nanotubes in a bulk composite, where an epoxy polymeric matrix is processed inside a high magnetic field to mediate the reorientation process of the carbon nanotubes. The alignment process is characterized by environmental scanning electron microscopy (ESEM), atomic force microscopy (AFM) and wide-angle x-ray diffraction (WAXD). Based on the current investigation, it is evident that magnetic alignment is a phenomenon closely related to the self-organizing process of the polymeric system. The microstructures of the polymer samples processed in 15 and 25 tesla fields are shown to have local orientation along the field's directions. The WAXD show a high degree of alignment when the azimuthal scan is parallel to the field direction ?=90° and 2?=19°. The alignment is more pronounced as a function of magnetic field strength. The field-assisted reorientation of the epoxy samples induce the alignment of the carbon nanotubes at the nanoscale level, while the carbon nanotubes ropes do not align globally due to their length.

Al-Haik, M. S.; Garmestani, H.; Li, D. S.; Hussaini, M. Y.; Dahmen, K.; Tannenbaum, R.

2005-07-01

55

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

56

Dielectric, magnetic, and microwave absorbing properties of multi-walled carbon nanotubes filled with Sm 2O 3 nanoparticles  

Microsoft Academic Search

This study investigates the dielectric, magnetic, and microwave absorbing properties of Sm2O3-filled multi-walled carbon nanotubes (MWCNTs) synthesized by wet chemical method. The complex permittivity and permeability were measured at a microwave frequency range of 2–18 GHz. Sm2O3 nanoparticles encapsulated in the cavities enhance the magnetic loss of MWCNTs. The calculated results indicate that the bandwith of absorbing peak of the modified

Lan Zhang; Hong Zhu

2009-01-01

57

Coherent mesoscopic transport through a quantum-dot embedded carbon nanotube ring threaded with magnetic flux  

NASA Astrophysics Data System (ADS)

We have investigated the coherent mesoscopic transport through a quantum-dot (QD) embedded carbon nanotube ring (CNR) by employing the nonequilibrium Green's function (NGF) technique. The Landauer-Büttiker-like formula is presented to calculate the differential conductance and current-voltage characteristics. Due to the interference of the electrons transporting in the two paths of CNR, the resultant conductivity of electron through the system is determined by the compound concrete structure of CNR-QD system. The tunneling current appears quantum behavior obviously in the small region of source-drain bias. The conductance is adjusted by the gate voltage Vg and the magnetic flux ?. The reversal resonance has been displayed versus the gate voltage, and it is symmetric about Vg for the type I CNR, but it is asymmetric for the type II CNR. The phase inverse oscillations are also presented for the different types of CNRs.

Zhao, Hong-Kang; Wang, Jian

2004-03-01

58

CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Synthesis and Properties of Magnetic Composites of Carbon Nanotubes/Fe Nanoparticle  

NASA Astrophysics Data System (ADS)

Magnetic composites of carbon nanotubes (CNTs) are synthesized by the in situ catalytic decomposition of benzene at temperatures as low as 400°C over Fe nanoparticles (mean grain size = 26 nm) produced by sol-gel fabrication and hydrogen reduction. The yield of CNT composite is up to about 3025% in a run of 6 h. FESEM and HRTEM investigations reveal that one-dimensional carbon species are produced in a large quantity. A relatively high value of magnetization is observed for the composite due to the encapsulation of ferromagnetic Fe3C and/or ?-Fe. The method is suitable for the mass-production of CNT composites that contain magnetic nanoparticles.

Xu, Mei-Hua; Qi, Xiao-Si; Zhong, Wei; Ye, Xiao-Juan; Deng, Yu; Au, Chaktong; Jin, Chang-Qing; Yang, Zai-Xing; Du, You-Wei

2009-11-01

59

Carbon Nanotubes in Neuroscience  

PubMed Central

Carbon nanotubes have electrical, mechanical and chemical properties that make them one of the most promising materials for applications in neuroscience. Single-walled and multi-walled carbon nanotubes have been increasingly used as scaffolds for neuronal growth and more recently for neural stem cell growth and differentiation. They are also used in interfaces with neurons, where they can detect neuronal electrical activity and also deliver electrical stimulation to these cells. The emerging picture is that carbon nanotubes do not have obvious adverse effects on mammalian health. Thus in the near future they could be used in brain–machine interfaces. PMID:19812974

Malarkey, Erik B.

2010-01-01

60

Carbon nanotube quantum resistors  

PubMed

The conductance of multiwalled carbon nanotubes (MWNTs) was found to be quantized. The experimental method involved measuring the conductance of nanotubes by replacing the tip of a scanning probe microscope with a nanotube fiber, which could be lowered into a liquid metal to establish a gentle electrical contact with a nanotube at the tip of the fiber. The conductance of arc-produced MWNTs is one unit of the conductance quantum G0 = 2e2/h = (12.9 kilohms)-1. The nanotubes conduct current ballistically and do not dissipate heat. The nanotubes, which are typically 15 nanometers wide and 4 micrometers long, are several orders of magnitude greater in size and stability than other typical room-temperature quantum conductors. Extremely high stable current densities, J > 10(7) amperes per square centimeter, have been attained. PMID:9624050

Frank; Poncharal; Wang; Heer

1998-06-12

61

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

62

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

63

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

64

Removal of boron from aqueous solution using magnetic carbon nanotube improved with tartaric acid  

PubMed Central

Boron removal capacity of multi-walled carbon nanotubes (MWCNTs) modified with tartaric acid was investigated in this study. Modification of MWCNTs with tartaric acid was confirmed by Boehm surface chemistry method and fourier transform infra-red (FT-IR) spectroscopy. Experiments were performed to determine the adsorption isotherm and adsorption thermodynamic parameters of boron adsorption on tartaric acid modified MWCNTs (TA-MWCNTs). The effect of variables including initial pH, dosage of adsorbent, contact time and temperature was investigated. Analysis of data showed that adsorption equilibrium could be better described by Freundlich isotherm and the maximum adsorption capacities obtained at the pH of 6.0 was 1.97 mg/g. The estimated thermodynamic values of free energy (?G°), entropy (?S°) and enthalpy (?H°) indicated a spontaneous and an endothermic process. Furthermore, the TA-MWCNTs was magnetized for separation of boron-contaminated adsorbent from aqueous solution by applying magnetic field. The results showed that magnetic TA-MWCNTs particles were separated effectively after adsorption from contaminated water. PMID:24393401

2014-01-01

65

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

66

Carbon nanotube solar cells.  

PubMed

We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement. PMID:22655070

Klinger, Colin; Patel, Yogeshwari; Postma, Henk W Ch

2012-01-01

67

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

68

Plasma patterning of carbon nanotubes  

Microsoft Academic Search

We have prepared micropatterns of carbon nanotubes on a wide range of substrates either by patterned growth of aligned nanotubes on surfaces prepatterned with plasma polymers (e.g., n-hexane plasma polymer) or through region-specific adsorption of certain chemically modified carbon nanotubes (e.g., -COOH substituted nanotubes) onto surfaces prepatterned with various plasma-generated functionalities (e.g., -NH2). Micropatterns of carbon nanotubes prepared in both

Qidao Chen; Liming Dai

2000-01-01

69

Ab initio study of magnetic and electronic properties of Fe-filled single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We investigate the electronic and magnetic properties of a metallic (3, 3) single-walled carbon nanotube (SWCNT) filled with a linear Fe nanowire, based on the ab initio spin-polarized density functional theory. We find that in the stable structure the Fe-filled (3, 3), (5, 0) SWCNTs exhibit semiconducting properties, and the Fe nanowires lose their magnetic moment, while the (4, 4), (5, 5), (6, 6), (6, 0) SWCNTs having larger radius with linear Fe nanowires are metallic, and show magnetic moments.

Rahman, M. M.; Kisaku, M.; Kishi, T.; Matsunaka, D.; Diño, W. A.; Nakanishi, H.; Kasai, H.

2004-12-01

70

Electronic structure and magnetic properties of 14N@C 60 within single-walled carbon nanotube as peapods  

NASA Astrophysics Data System (ADS)

Design of spin labels inside for possible molecular spintronics, which contains 1D spin chain filling single-walled carbon nanotube (SWCNT) with magnetic endohedral fullerenes of 14N@C 60, has been suggested. Electronic structure and magnetic properties of 14N@C 60-SWCNT armchair for chiral index ( n, n) n=9-13 in contrast with SWCNT and 14N@C 60 were characterized. Especially, influence of the SWCNT diameter on electronic structure, magnetic parameters of chemical shift of 13C, principal g-tensor and hyperfine coupling constant of nitrogen atom was investigated by ab-initio density functional theory.

Suzuki, Atsushi; Oku, Takeo; Kikuchi, Kenji

2010-05-01

71

Vaccine Delivery by Carbon Nanotubes  

Microsoft Academic Search

Novel nanomaterials, such as carbon nanotubes, are under active investigation for potential use in biomedical applications. In this issue of Chemistry & Biology, researchers describe antigen-antibody interactions and immune responses using peptide-carbon nanotube conjugates.

Marc in het Panhuis

2003-01-01

72

Sensor applications of carbon nanotubes  

E-print Network

A search of published research on sensing mechanisms of carbon nanotubes was performed to identify applications in which carbon nanotubes might improve on current sensor technologies, in either offering improved performance, ...

Rushfeldt, Scott I

2005-01-01

73

Magneto-optical spectroscopy of highly aligned carbon nanotubes: Identifying the role of threading magnetic flux  

E-print Network

of 1D magnetoexcitonic bands14,15 based on the Aharonov- Bohm effect.16,21­23 PL measurements were bands with Aharonov-Bohm-phase-dependent energies, masses, and oscillator strengths, successfullyMagneto-optical spectroscopy of highly aligned carbon nanotubes: Identifying the role of threading

Kono, Junichiro

74

Carbon Nanotubes for Supercapacitor  

PubMed Central

As an electrical energy storage device, supercapacitor finds attractive applications in consumer electronic products and alternative power source due to its higher energy density, fast discharge/charge time, low level of heating, safety, long-term operation stability, and no disposable parts. This work reviews the recent development of supercapacitor based on carbon nanotubes (CNTs) and their composites. The purpose is to give a comprehensive understanding of the advantages and disadvantages of carbon nanotubes-related supercapacitor materials and to find ways for the improvement in the performance of supercapacitor. We first discussed the effects of physical and chemical properties of pure carbon nanotubes, including size, purity, defect, shape, functionalization, and annealing, on the supercapacitance. The composites, including CNTs/oxide and CNTs/polymer, were further discussed to enhance the supercapacitance and keep the stability of the supercapacitor by optimally engineering the composition, particle size, and coverage. PMID:20672061

2010-01-01

75

Characterization, charge transport and magnetic properties of multi-walled carbon nanotube-polyvinyl chloride nanocomposites  

NASA Astrophysics Data System (ADS)

Multi-walled carbon nanotube (MWCNT)-polyvinyl chloride (PVC) nanocomposites, with MWCNT loading up to 44.4 weight percent (wt%), were prepared by the solvent mixing and casting method. Electron microscopy indicates high degree of dispersion of MWCNT in PVC matrix, achieved by ultrasonication without using any surfactants. Thermogravimetric analysis showed a significant monotonic enhancement in the thermal stability of nanocomposites by increasing the wt% of MWCNT. Electrical conductivity of nanocomposites followed the classical percolation theory and the conductivity prominently improved from 10-7 to 9 S/cm as the MWCNT loading increased from 0.1 to 44.4 wt%. Low value of electrical percolation threshold ~0.2 wt% is achieved which is attributed to high aspect ratio and homogeneous dispersion of MWCNT in PVC. The analysis of the low temperature electrical resistivity data shows that sample of 1.9 wt% follows three dimensional variable range hopping model whereas higher wt% nanocomposite samples follow power law behavior. The magnetization versus applied field data for both bulk MWCNTs and nanocomposite of 44.4 wt% display ferromagnetic behavior with enhanced coercivities of 1.82 and 1.27 kOe at 10 K, respectively. The enhancement in coercivity is due to strong dipolar interaction and shape anisotropy of rod-shaped iron nanoparticles.

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

2014-02-01

76

Magnetically steered liquid crystal-nanotube switch  

NASA Astrophysics Data System (ADS)

A magnetically steered electric switch based on nematic liquid crystal-single-wall carbon nanotube dispersions is demonstrated. The device exploits the conductivity anisotropy of nanotubes in combination with the magnetic Freedericksz transition of a nematic liquid crystal. The performance is characterized with respect to the electric measuring field amplitude, frequency and sample cell gap. The dynamic behavior indicates a response time of approximately 4s, and possible applications for magnetic field sensors are discussed.

Dierking, Ingo; San, S. Eren

2005-12-01

77

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

78

Hybrid magnetic amphiphilic composites based on carbon nanotube/nanofibers and layered silicates fragments as efficient adsorbent for ethynilestradiol.  

PubMed

In this work, hybrid magnetic amphiphilic composites were prepared by the catalytic growth of carbon nanotubes (CNTs) and nanofibers CNF on layered silicates fragments. SEM, TEM, Raman, XRD, Mössbauer, TG/DTA showed that CVD with CH(4) at 800°C produced CNF and magnetic Fe cores fixed on the surface of microfragments of silicates layers. Due to the amphiphilic character, the composites can be easily dispersed in water and efficiently adsorb hydrophobic contaminant molecules. For example, the composites showed remarkable adsorption capacities for the hormone ethinylestradiol, e.g. 2-4 mg m(-2), compared to ca. 0.1 mg m(-2) obtained for high surface area activated carbon and multiwall CNT. These results are discussed in terms of a high hydrophobic exposed surface area of the CNT and CNF fixed on the layered silicates fragments surface. Moreover, the composites can be easily removed from water by a simple magnetic separation process. PMID:22608147

Purceno, Aluir D; Teixeira, Ana Paula C; de Souza, Nubia Janaína; Fernandez-Outon, Luis E; Ardisson, José D; Lago, Rochel M

2012-08-01

79

Polarized light transmission in ferrofluids loaded with carbon nanotubes in the presence of a uniform magnetic field  

NASA Astrophysics Data System (ADS)

Magneto-optic phenomena in ferrofluids have been shown to be related to the formation of chain structures, due to the arrangement of the ferromagnetic particles, induced by an applied magnetic field. In this work, the effects on transmission of polarized light due to anisotropic effects induced by an external magnetic field in ferrofluids with carbon nanotubes are studied. The time response of the system presents two well defined stages, in the first one, which is very short, the fluid behaves as a polarizer. In contrast in the second stage, the effects of light transmission dominate. In this stage the transmitted light intensity grows with time and after a long time reaches a constant stable value. It is shown that these phenomena depend on the carbon nanotubes concentration as well as on the strength of the applied magnetic field. Using a simple model that considers a chain-like structure formation, it is possible to determine the rate of agglomeration of the formed structures and the attenuation coefficient of the transmitted light. The formation of nanostructures leads to variation in the transmitted light, depending on the polarization of the incident light. These magnetic nanostructures can find numerous applications in nanotechnology, optical devices and medicine.

Vales-Pinzón, C.; Alvarado-Gil, J. J.; Medina-Esquivel, R.; Martínez-Torres, P.

2014-11-01

80

The biocompatibility of carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes (CNT) are well-ordered, high aspect ratio allotropes of carbon. The two main variants, single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) both possess a high tensile strength, are ultra-light weight, and have excellent chemical and thermal stability. They also possess semi- and metallic-conductive properties. This startling array of features has led to many proposed applications in the

S. K. Smart; A. I. Cassady; G. Q. Lu; D. J. Martin

2006-01-01

81

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

82

Structural, electronic and magnetic properties of hcp Fe, Co and Ni nanowires encapsulated in zigzag carbon nanotubes  

NASA Astrophysics Data System (ADS)

The structural, electronic and magnetic properties of hcp transition metal (TM = Fe, Co or Ni) nanowires TM4 encapsulated inside zigzag nanotubes C( m, 0) ( m = 7, 8, 9, 10, 11 or 12), along with TM n ( n = 4, 10 or 13) encapsulated inside C(12, 0), have been systematically investigated using the first-principle calculations. The results show that the TM nanowires can be inserted inside a variety of zigzag carbon nanotubes (CNTs) exothermically, except from the systems TM4@(7, 0) and TM13@(12, 0) which are endothermic. The charge is transferred from TM nanowires to CNTs, and the transferred charge increases with decreasing CNT diameter or increasing nanowire thickness. The magnetic moments of hybrid systems are smaller than those of the freestanding TM nanowires, especially for the atoms on the outermost shell of the nanowires. The magnetic moment per TM atom of TM/CNT system increases with increasing CNT diameter or decreasing nanowire thickness. Both the density of states and spin charge density analysis show that the spin polarization and the magnetic moments of all hybrid systems mainly originate from the TM nanowires, implying these systems can be applied in magnetic data storage devices.

Xie, Y.; Zhang, J. M.; Huo, Y. P.

2011-06-01

83

Purification of Carbon Nanotubes: Alternative Methods  

NASA Technical Reports Server (NTRS)

Traditional carbon nanotube purification process involves nitric acid refluxing and cross flow filtration using surfactant TritonX. This is believed to result in damage to nanotubes and surfactant residue on nanotube surface. Alternative purification procedures involving solvent extraction, thermal zone refining and nitric acid refiuxing are used in the current study. The effect of duration and type of solvent to dissolve impurities including fullerenes and P ACs (polyaromatic compounds) are monitored by nuclear magnetic reasonance, high performance liquid chromatography, and thermogravimetric analysis. Thermal zone refining yielded sample areas rich in nanotubes as seen by scanning electric microscopy. Refluxing in boiling nitric acid seem to improve the nanotube content. Different procedural steps are needed to purify samples produced by laser process compared to arc process. These alternative methods of nanotube purification will be presented along with results from supporting analytical techniques.

Files, Bradley; Scott, Carl; Gorelik, Olga; Nikolaev, Pasha; Hulse, Lou; Arepalli, Sivaram

2000-01-01

84

Carbon nanotube suspensions, dispersions, & composites  

Microsoft Academic Search

Carbon Nanotubes (CNTs) are amazing structures that hold the potential to revolutionize many areas of scientific research. CNTs can be behave both as semiconductors and metals, can be grown in highly ordered arrays and patterns or in random orientation, and can be comprised of one graphene cylinder (single wall nanotube, SWNT) or several concentric graphene cylinders (multi-wall nanotube, MWNT). Although

Trevor John Simmons

2008-01-01

85

Method of manufacturing carbon nanotubes  

NASA Technical Reports Server (NTRS)

A process for manufacturing carbon nanotubes, including a step of inducing electrical current through a carbon anode and a carbon cathode under conditions effective to produce the carbon nanotubes, wherein the carbon cathode is larger than the carbon anode. Preferably, a welder is used to induce the electrical current via an arc welding process. Preferably, an exhaust hood is placed on the anode, and the process does not require a closed or pressurized chamber. The process provides high-quality, single-walled carbon nanotubes, while eliminating the need for a metal catalyst.

Benavides, Jeanette M. (Inventor); Leidecker, Henning W. (Inventor); Frazier, Jeffrey (Inventor)

2004-01-01

86

Carbon Nanotube Array Immunosensor Development  

Microsoft Academic Search

This paper describes the development of a label-free immunosensor using carbon nanotube array electrodes. Highly aligned multi-walled carbon nanotubes were grown by chemical vapor deposition using a metallic catalyst, Fe\\/Al2O3\\/SiO2, On Si wafers. Harvested towers were cast in epoxy and polished on both ends; one end being for electrical connection and the other being the electrode array surface. The nanotubes

A. Bange; H. B. Halsall; W. R. Heineman; YeoHeung Yun; M. J. Schulz; V. Shanov

2006-01-01

87

Carbon nanotube Archimedes screws.  

PubMed

Recently, nanomechanical devices composed of a long stationary inner carbon nanotube and a shorter, slowly rotating outer tube have been fabricated. In this paper, we study the possibility of using such devices as nanoscale transducers of motion into electricity. When the outer tube is chiral, we show that such devices act like quantum Archimedes screws, which utilize mechanical energy to pump electrons between reservoirs. We calculate the pumped charge from one end of the inner tube to the other, driven by the rotation of a chiral outer nanotube. We show that the pumped charge can be greater than one electron per 360° rotation, and consequently, such a device operating with a rotational frequency of 10 MHz, for example, would deliver a current of ?1 pAmp. PMID:21126086

Oroszlány, László; Zólyomi, Viktor; Lambert, Colin J

2010-12-28

88

Carbon Nanotube Reinforced Polymer Nanocomposites  

E-print Network

Carbon Nanotube Reinforced Polymer Nanocomposites: Engineering the Interface at the Nano-Domain Wei of Art The Northrop Grumman Global Hawk is an unmanned aerial vehicle (UAV) Nano - Composites Polymer Nanocomposites The Ideal "Straws" ­ Carbon Nanotubes 7.80.4208Steel 2.61501200MWCNT 1.341501054SWCNT Density (g

Southern California, University of

89

Electronic Transport Spectroscopy of Carbon Nanotubes in a Magnetic Field P. Jarillo-Herrero, J. Kong,* H. S. J. van der Zant, C. Dekker, L. P. Kouwenhoven, and S. De Franceschi  

E-print Network

Electronic Transport Spectroscopy of Carbon Nanotubes in a Magnetic Field P. Jarillo-Herrero, J, 73.22.-f, 73.23.Hk The remarkable electronic behavior of carbon nanotubes (CNTs) originates from. In this Letter, we report B-dependent electronic trans- port spectroscopy measurements on CNT QDs exhibiting

Dekker, Cees

90

Carbon nanotubes: properties and application  

Microsoft Academic Search

Carbon nanotubes are unique tubular structures of nanometer diameter and large length\\/diameter ratio. The nanotubes may consist of one up to tens and hundreds of concentric shells of carbons with adjacent shells separation of ?0.34nm. The carbon network of the shells is closely related to the honeycomb arrangement of the carbon atoms in the graphite sheets. The amazing mechanical and

Valentin N Popov

2004-01-01

91

Surface Modification of Aligned Carbon Nanotubes  

Microsoft Academic Search

The excellent optoelectronic, mechanical, and thermal properties of carbon nanotubes have made them very attractive for a wide range of potential applications. However, many applications require the growth of aligned carbon nanotubes with desirable surface characteristics. We have developed a simple pyrolytic method for large-scale production of aligned carbon nanotube arrays perpendicular to the substrate. These aligned carbon nanotube arrays

Liming Dai; Ajeeta Patil; Richard A. Vaia

2003-01-01

92

Platinum carbon nanotube interaction  

NASA Astrophysics Data System (ADS)

The interaction between evaporated Pt and pristine or oxygen-plasma-treated multiwall carbon nanotubes (CNTs) is investigated. Pt is found to nucleate at defect sites, whether initially present or introduced by oxygen plasma treatment. The plasma treatment induces a uniform dispersion of Pt nanoparticles at the CNT surface. The absence of additional features in the C 1 s core level spectrum indicates that no mixed Pt-C phase is formed. The formation of C-O-Pt bonds at the cluster-CNT interface is suggested to reduce the electronic interaction between Pt nanoparticles and the CNT surface.

Bittencourt, C.; Hecq, M.; Felten, A.; Pireaux, J. J.; Ghijsen, J.; Felicissimo, M. P.; Rudolf, P.; Drube, W.; Ke, X.; Van Tendeloo, G.

2008-09-01

93

Carbon nanotubes: biomaterial applications.  

PubMed

There is increasing interest in the unique biological and medical properties of carbon nanotubes (CNTs), and it is expected that biomaterials incorporating CNTs will be developed for clinical use. There has been a great deal of progress in improving the various properties of CNTs for use in biomaterials and for promotion of tissue regeneration as scaffold materials. The effects of CNTs on cells and tissues are extremely important for their use in biomaterials. This tutorial review clarifies the current state of knowledge in the interdisciplinary field of CNT-based nanobiotechnology to determine whether CNTs may be useful in biomaterials. Future perspectives in this rapidly developing field will also be discussed. PMID:19551170

Saito, Naoto; Usui, Yuki; Aoki, Kaoru; Narita, Nobuyo; Shimizu, Masayuki; Hara, Kazuo; Ogiwara, Nobuhide; Nakamura, Koichi; Ishigaki, Norio; Kato, Hiroyuki; Taruta, Seiichi; Endo, Morinobu

2009-07-01

94

Carbon Nanotubes for Space Applications  

NASA Technical Reports Server (NTRS)

The potential of nanotube technology for NASA missions is significant and is properly recognized by NASA management. Ames has done much pioneering research in the last five years on carbon nanotube growth, characterization, atomic force microscopy, sensor development and computational nanotechnology. NASA Johnson Space Center has focused on laser ablation production of nanotubes and composites development. These in-house efforts, along with strategic collaboration with academia and industry, are geared towards meeting the agency's mission requirements. This viewgraph presentation (including an explanation for each slide) outlines the research focus for Ames nanotechnology, including details on carbon nanotubes' properties, applications, and synthesis.

Meyyappan, Meyya

2000-01-01

95

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

96

Aharonov-Bohm effect in carbon nanotubes  

Microsoft Academic Search

Optical absorption spectra are calculated in carbon nanotubes in the presence of a magnetic flux parallel to the tube axis. A drastic change in the band gap manifests itself in optical spectra for light polarization parallel to the axis. In the case of perpendicular polarization, the absorption is suppressed by a large depolarization effect.

Hiroshi Ajiki; Tsuneya Ando

1994-01-01

97

Nanoscale atomic waveguides with suspended carbon nanotubes  

E-print Network

We propose an experimentally viable setup for the realization of one-dimensional ultracold atom gases in a nanoscale magnetic waveguide formed by single doubly-clamped suspended carbon nanotubes. We show that all common decoherence and atom loss mechanisms are small guaranteeing a stable operation of the trap. Since the extremely large current densities in carbon nanotubes are spatially homogeneous, our proposed architecture allows to overcome the problem of fragmentation of the atom cloud. Adding a second nanowire allows to create a double-well potential with a moderate tunneling barrier which is desired for tunneling and interference experiments with the advantage of tunneling distances being in the nanometer regime.

V. Peano; M. Thorwart; A. Kasper; R. Egger

2005-05-27

98

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

99

Development of magnetic molecularly imprinted polymers based on carbon nanotubes - application for trace analysis of pyrethroids in fruit matrices.  

PubMed

The sensitive and efficient magnetic molecularly imprinted polymers (MMIPs) were successfully synthesized using carbon nanotubes as matrix and Fe3O4 particles as magnetic ingredient. Tetraethyl orthosilicate was used as modification material of the carbon nanotubes. Cyhalothrin, methacrylic acid and ethylene glycol dimethacrylate were used as template molecule, functional monomer and cross-linker, respectively. Azo-isobutyronitrile and polyvinylpyrrolidone were used as initiator and dispersant, respectively. The MMIPs were used for the separation of pyrethroids including beta-cyfluthrin, cyhalothrin, cyphenothrin and permethrin in fruit samples followed by high performance liquid chromatography analysis. The polymers were characterized with Fourier transform infrared spectrometry, Brunauer-Emmett-Teller method, transmission electron microscopy and a physical property measurement system. The isothermal absorption experiment, kinetics absorption experiment and selectivity of MMIPs were studied in detail. Scatchard analysis revealed that two kinds of different binding sites existed in MMIPs. The maximum adsorption capacities of two binding sites were 65.21 and 189.83mgg(-1), and dissociation constants were 7.11 and 30.40?gmL(-1), respectively. The kinetic property of MMIPs was well fitted to the second-order equation. The selectivity experiment indicated that MMIPs had higher selectivity toward cyhalothrin and its structural analogs than reference compound. The feasibility of detecting pyrethroids from real samples was testified in spiked fruit samples with different concentrations (0.025, 0.25 and 2.5mgkg(-1)). The LODs of beta-cyfluthrin, cyhalothrin, cyphenothrin and permethrin were 0.0072, 0.0035, 0.0062 and 0.0068mgkg(-1), respectively. Precisions of intra-day and inter-day ranging from 2.6% to 4.3% and 4.2% to 5.6% were obtained, respectively. This method was applied to determine pyrethroids in different fruit samples including apple, pear, orange, grape and peach, and satisfied recoveries (82.4-101.7%) were obtained. PMID:24418237

Ma, Guifu; Chen, Ligang

2014-02-14

100

Modifying Nanotubes Chemistry and Electronics of Carbon Nanotubes  

E-print Network

One of the critical issues for the application of single-wall carbon nano- tubes (SWCNTs-wall carbon nanotubes is demonstrated by Kamaras et al.,[3] who treated the nano- tubes with dichlorocarbeneModifying Nanotubes Chemistry and Electronics of Carbon Nanotubes Go Together Ernesto Joselevich

Joselevich, Ernesto

101

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

102

Excitons in Single-Walled Carbon Nanotubes in Different Local Environments: Effects of Strain and Disorder on Magnetic Brightening  

NASA Astrophysics Data System (ADS)

Recent experiments on single-walled carbon nanotubes (SWNTs) have shown that in the presence of a high magnetic field the two lowest-energy spin-singlet exciton states become bright [1]. Furthermore, this ``magnetic brightening'', or increase in photoluminescence (PL) intensity as a function of magnetic flux through each SWNT, increases as the temperature decreases. Here, we report results of temperature-dependent magneto-PL from 2 to 200 K and up to 45 T on SWNTs of the same stock solution suspended in four different local environments. We compared both the brightening and temperature dependence of tubes stretch aligned and unaligned in poly-acrylic acid matrices. As expected, the tubes aligned at high magnetic field exhibited more brightening than those unaligned. We also investigated the behavior of SWNTs in two other matrices, iota-Carrageenan and gelatin. Along with the expected peak shifting and broadening from the effects of strain, we found that the temperature dependence changes with local environment. [1] S. Zaric et al., PRL 96, 016406 (2006); J. Shaver et al., Nano Lett. 7, 1851 (2007); I. B. Mortimer and R. J. Nicholas, PRL 98, 027404 (2007).

Searles, T. A.; Hilton, D. J.; Shaver, J.; Rice, W. D.; Jho, Y.-D.; McGill, S. A.; Fagan, J. A.; Hobbie, E. K.; Kono, J.

2008-03-01

103

Carbon Nanotube Actuators  

NASA Astrophysics Data System (ADS)

We have demonstrated a new type of electromechanical actuator, which is based on both a new type of actuator material (single-wall carbon nanotubes) and a new type of actuation mechanism (double-layer charge injection). Like natural muscles, the macroscopic actuators are assemblies of billions of individual nanoscale actuators. Higher stress generation capabilities than natural muscles and higher strains than high modulus ceramics were obtained in investigations of both all-solid-state and liquid-electrolyte-based devices. Evidence of giant charge injection is provided by in-situ measurements of electrochemical voltametry and Raman, UV-visible, and impedance spectroscopies. The results of ab initio quantum chemical calculations show that actuation arises from bond length changes that principally originate from quantum chemical effects, rather than electrostatic effects. Based on analysis of measurements, we conclude that nanotube actuators will eventually provide much higher specific work capacities and stress generation capabilities than alternative technologies, while operating at an order of magnitude lower voltages than ferroelectrics. We have demonstrated device operation to above 650 K, and conclude (based on observations of redox stability) that actuator operation to above 1300 K will eventually be feasible.

Baughman, Ray H.

2000-03-01

104

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

105

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

106

Carbon nanotube electron gun  

NASA Technical Reports Server (NTRS)

An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

2010-01-01

107

Carbon Nanotube Electronics and Optoelectronics  

Microsoft Academic Search

Carbon nanotube field-effect transistors (CNFETs) are already competitive in some respects with state-of-the-art silicon transistors,\\u000a and are promising candidates for future nanoelectronic devices. However, it is dificult to form ohmic contacts to carbon nanotubes,\\u000a and most of the CNFETs reported to date operate as Schottky barrier transistors rather than conventional FETs. The electrostatics\\u000a at the contact of a metal to

Stefan Heinze; Jerry Tersoff; Phaedon Avouris

2005-01-01

108

PECVD Growth of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

Plasma enhanced chemical vapor deposition (PECVD), using inductively coupled plasma, has been used to grow carbon nanotubes (CNTs) and graphitic carbon fibers (GCF) on substrates sputtered with aluminum and iron catalyst. The capacitive plasma's power has been shown to cause a transition from nanotubes to nanofibers, depending on the strength of the plasma. The temperature, placement, and other factors have been shown to affect the height and density of the tube and fiber growth.

McAninch, Ian; Arnold, James O. (Technical Monitor)

2001-01-01

109

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

110

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

111

The carbon nanotube radio  

Microsoft Academic Search

The characteristics of the nanotube radio are improved considering new configurations based on quantum tunneling. In this way, the new invented nanotube radio could be tuned electrically in the entire FM or AM bands and biased with miniaturized batteries.

M. Dragoman; D. Dragoman

2008-01-01

112

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

113

Nanotechnology with Carbon Nanotubes: Mechanics, Chemistry, and Electronics  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the Nanotechnology of carbon nanotubes. The contents include: 1) Nanomechanics examples; 2) Experimental validation of nanotubes in composites; 3) Anisotropic plastic collapse; 4) Spatio-temporal scales, yielding single-wall nanotubes; 5) Side-wall functionalization of nanotubes; 6) multi-wall Y junction carbon nanotubes; 7) Molecular electronics with Nanotube junctions; 8) Single-wall carbon nanotube junctions; welding; 9) biomimetic dendritic neurons: Carbon nanotube, nanotube electronics (basics), and nanotube junctions for Devices,

Srivastava, Deepak

2003-01-01

114

Magnetic carbon nanotubes synthesis by Fenton's reagent method and their potential application for removal of azo dye from aqueous solution.  

PubMed

We report a simple and easy method to fabricate magnetic carbon nanotubes (CNTs) by Fenton's reagent method without the addition of any cations. H(2)O(2) was added slowly into the FeSO(4) solution mixed with purified CNTs, and the resulting reactants were placed into a quartz tube to undergo heat treatment under a nitrogen/hydrogen flow. Iron oxide (Fe(2)O(3)) nanoparticles were uniformly dispersed on CNTs without any pretreatment such as strong acid or covalent functionalization processes. The as-produced magnetic CNTs were used as an adsorbent for removal of methyl orange (MO) dye from aqueous solutions. Adsorption experiments indicated that the magnetic CNTs have good adsorption capacity (q(e)) of MO (28 mg/g). The Freundlich isotherm model fitted the experiment data better than the Langmuir isotherm mode. The mean energy of adsorption was calculated as 3.72 kJ/mol based on the Dubinin-Radushkevich model, which suggests that the removal process was dominated by physical adsorption. Kinetic regression results showed that the adsorption kinetics was more accurately represented by a pseudo second-order model. Intra-particle diffusion was involved in the adsorption process, but it was not the only rate-controlling step. More importantly, a new photocatalytic regeneration technology can be enabled by the high nanoscale iron oxide loading (50%). The magnetic CNT adsorbents could be effectively and quickly separated by applying an external magnetic field and regenerated by UV photocatalysis. Therefore, CNTs/?-Fe(2)O(3) hybrid is a promising magnetic nanomaterial for preconcentration and separation of organic pollutants for environmental remediation. PMID:22564767

Yu, Fei; Chen, Junhong; Chen, Lu; Huai, Jing; Gong, Wenyi; Yuan, Zhiwen; Wang, Jinhe; Ma, Jie

2012-07-15

115

Multiwall carbon nanotubes decorated with NiFe2O4 magnetic nanoparticles, a new catalyst for voltammetric determination of cefixime.  

PubMed

Multiwall carbon nanotubes were decorated with synthesized NiFe(2)O(4) magnetic nanoparticles. The new materials were characterized with different techniques such as transform infrared spectroscopy, transmission electron microscopy, atomic force microscopy and electrochemical impedance spectroscopy. The multiwall carbon nanotubes decorated with NiFe(2)O(4) magnetic nanoparticles was used as a new mediator for the voltammetric determination of cefixime. Under the optimum conditions at pH 8.0, the oxidation of cefixime was occurred at 850 mV at the surface of the modified electrode. Linear sweep voltammetry exhibited two wide linear dynamic ranges of 0.1-100 and 100-600 ?mol L(-1) cefixime. The detection limit was found to be 0.02 ?mol L(-1) cefixime. Finally, the modified electrode showed good sensitivity, selectivity and stability for the determination of cefixime in real samples. PMID:23107947

Ensafi, Ali A; Allafchian, Ali R

2013-02-01

116

Aharonov-Bohm exciton splitting in the optical absorption of chiral-specific single-walled carbon nanotubes in magnetic fields up to 78 T  

Microsoft Academic Search

The Ajiki-Ando (A-A) splitting of single-walled carbon nanotubes (SWNTs) originating from the Aharanov-Bohm effect was observed in chiral-specific SWNTs by the magneto-absorption measurements conducted at magnetic fields of up to 78 T. The absorption spectra from each chirality showed clear A-A splitting of the E11 optical excitonic transitions. The parameters of both the dark-bright exciton energy splitting and the rate

Shojiro Takeyama; Hirofumi Suzuki; Hiroyuki Yokoi; Yoichi Murakami; Shigeo Maruyama

2011-01-01

117

Mechanical energy storage in carbon nanotube springs  

E-print Network

Energy storage in mechanical springs made of carbon nanotubes is a promising new technology. Springs made of dense, ordered arrays of carbon nanotubes have the potential to surpass both the energy density of electrochemical ...

Hill, Frances Ann

2011-01-01

118

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

119

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

120

Peptides with selective affinity for carbon nanotubes  

Microsoft Academic Search

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

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

2003-01-01

121

Dispersions of Carbon nanotubes in Polymer Matrices  

NASA Technical Reports Server (NTRS)

Dispersions of carbon nanotubes exhibiting long term stability are based on a polymer matrix having moieties therein which are capable of a donor-acceptor complexation with carbon nanotubes. The carbon nanotubes are introduced into the polymer matrix and separated therein by standard means. Nanocomposites produced from these dispersions are useful in the fabrication of structures, e.g., lightweight aerospace structures.

Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

2010-01-01

122

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

123

Viscoelasticity in carbon nanotube composites  

NASA Astrophysics Data System (ADS)

Polymer composites reinforced by carbon nanotubes have been extensively researched for their strength and stiffness properties. Unless the interface is carefully engineered, poor load transfer between nanotubes (in bundles) and between nanotubes and surrounding polymer chains may result in interfacial slippage and reduced performance. Interfacial shear, although detrimental to high stiffness and strength, could result in very high mechanical damping, which is an important attribute in many commercial applications. We previously reported evidence of damping in nanocomposites by measuring the modal response (at resonance) of cantilevered beams with embedded nanocomposite films. Here we carry out direct shear testing of epoxy thin films containing dense packing of multiwalled carbon nanotube fillers and report strong viscoelastic behaviour with up to 1,400% increase in loss factor (damping ratio) of the baseline epoxy. The great improvement in damping was achieved without sacrificing the mechanical strength and stiffness of the polymer, and with minimal weight penalty. Based on the interfacial shear stress (~0.5 MPa) at which the loss modulus increases sharply for our system, we conclude that the damping is related to frictional energy dissipation during interfacial sliding at the large, spatially distributed, nanotube-nanotube interfaces.

Suhr, Jonghwan; Koratkar, Nikhil; Keblinski, Pawel; Ajayan, Pulickel

2005-02-01

124

Kinetics and thermodynamics of the sorption of furaltadone from aqueous solutions on magnetic multi-walled carbon nanotubes.  

PubMed

Magnetic multi-wall carbon nanotubes (M-MWCNTs) were used as an adsorbent for removal of furaltadone from aqueous solutions, and the adsorption behaviors were investigated by varying pH, sorbent amount, sorption time and temperature. The results showed that the adsorption efficiency of furaltadone reached 97% when the dosage of M-MWCNT was 0.45 g · L?¹, the pH was 7 and the adsorption time was 150 min. The kinetic data showed that the pseudo-second-order model can fit the adsorption kinetics. The sorption data could be well explained by the Langmuir model under different temperatures. The adsorption process was influenced by both intraparticle diffusion and external mass transfer. The experimental data analysis indicated that the electrostatic attraction and ?-? stacking interactions between M-MWCNT and furaltadone might be the adsorption mechanism. Thermodynamic analysis reflected that adsorption of furaltadone on the M-MWCNT was spontaneous and exothermic. Our study showed that M-MWCNTs can be used as a potential adsorbent for removal of furaltadone from water and wastewater. PMID:25259483

Chen, Xu; Xiong, Zhen-hu

2014-01-01

125

CMOS Integrated Carbon Nanotube Sensor  

SciTech Connect

Recently carbon nanotubes (CNTs) have been gaining their importance as sensors for gases, temperature and chemicals. Advances in fabrication processes simplify the formation of CNT sensor on silicon substrate. We have integrated single wall carbon nanotubes (SWCNTs) with complementary metal oxide semiconductor process (CMOS) to produce a chip sensor system. The sensor prototype was designed and fabricated using a 0.30 um CMOS process. The main advantage is that the device has a voltage amplifier so the electrical measure can be taken and amplified inside the sensor. When the conductance of the SWCNTs varies in response to media changes, this is observed as a variation in the output tension accordingly.

Perez, M. S.; Lerner, B.; Boselli, A.; Lamagna, A. [Grupo MEMS, Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Obregon, P. D. Pareja; Julian, P. M.; Mandolesi, P. S. [Dpto. de Ing. Electrica y de Computadoras, Universidad Nacional del Sur, Bahia Blanca (Argentina); Buffa, F. A. [INTEMA Facultad de Ingenieria, Universidad Nacional de Mar del Plata, Mar del Plata (Argentina)

2009-05-23

126

Aharonov-Bohm exciton splitting in the optical absorption of chiral-specific single-walled carbon nanotubes in magnetic fields up to 78 T  

NASA Astrophysics Data System (ADS)

The Ajiki-Ando (A-A) splitting of single-walled carbon nanotubes (SWNTs) originating from the Aharanov-Bohm effect was observed in chiral-specific SWNTs by the magneto-absorption measurements conducted at magnetic fields of up to 78 T. The absorption spectra from each chirality showed clear A-A splitting of the E11 optical excitonic transitions. The parameters of both the dark-bright exciton energy splitting and the rate of A-A splitting in a magnetic field were determined for the first time from the well-resolved absorption spectra.

Takeyama, Shojiro; Suzuki, Hirofumi; Yokoi, Hiroyuki; Murakami, Yoichi; Maruyama, Shigeo

2011-06-01

127

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

128

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

129

Plasma CVD of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

Carbon nanotubes(CNT) exhibit remarkable mechanical and unique electronic properties and thus have created excitement in the research community about their potential in electronics, computing, sensor and structural applications. Realization of these applications critically depends on the ability to control the properties(such as diameter, chirality) as well purity. We have investigated CNT growth using an inductively coupled plasma(ICP) process using hydrocarbon feedstock. The catalyst required for nanotube growth consists of thin sputtered layers of aluminum and iron(10 nm each) and aligned carbon nanotubes have been obtained. Optical emission diagnostics as well as a plasma modeling effort have been undertaken to understand growth mechanisms. This presentation will discuss growth characteristics under various pressure, power and feedgas compositions and our understanding from modeling and diagnostics.

Delzeit, Lance; Cruden, B.; Hash, D.; Meyyappan, M.; DeVincenzi, Donald L. (Technical Monitor)

2001-01-01

130

Supported lipid bilayer/carbon nanotube hybrids  

NASA Astrophysics Data System (ADS)

Carbon nanotube transistors combine molecular-scale dimensions with excellent electronic properties, offering unique opportunities for chemical and biological sensing. Here, we form supported lipid bilayers over single-walled carbon nanotube transistors. We first study the physical properties of the nanotube/supported lipid bilayer structure using fluorescence techniques. Whereas lipid molecules can diffuse freely across the nanotube, a membrane-bound protein (tetanus toxin) sees the nanotube as a barrier. Moreover, the size of the barrier depends on the diameter of the nanotube-with larger nanotubes presenting bigger obstacles to diffusion. We then demonstrate detection of protein binding (streptavidin) to the supported lipid bilayer using the nanotube transistor as a charge sensor. This system can be used as a platform to examine the interactions of single molecules with carbon nanotubes and has many potential applications for the study of molecular recognition and other biological processes occurring at cell membranes.

Zhou, Xinjian; Moran-Mirabal, Jose M.; Craighead, Harold G.; McEuen, Paul L.

2007-03-01

131

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

132

BIOLOGICAL FUNCTIONALIZATION OF CARBON NANOTUBES  

Microsoft Academic Search

Carbon nanotubes are known for their exceptional mechanical and unique electronic properties. The size dependant properties of nanomaterials have made them attractive to develop highly sensitive sensors and detection systems. This is especially true in biological sciences, where the efficiency of detection systems reflect on the size of the detector and the sample required for detection. At approximately 1.5 to

Ranjani Sirdeshmukh; Kasif Teker; Balaji Panchapakesan; Delaware MEMS

133

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

134

Carbon nanotubes for orthopaedic implants  

Microsoft Academic Search

The physical and biological limitations of current orthopaedic implant materials are a major challenge for bone tissue engineering.\\u000a Nanotechnology has introduced new materials and methods for meeting this challenge. The application of nanotechnology to engineering\\u000a new bone substitutes finds a model in the nanoscale components of natural bone tissue. Carbon nanotubes are a macromolecular\\u000a form of carbon with exceptional properties

Rose L. Spear; Ruth E. Cameron

2008-01-01

135

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

136

Voltammetric behavior of dopamine at a glassy carbon electrode modified with NiFe(2)O(4) magnetic nanoparticles decorated with multiwall carbon nanotubes.  

PubMed

Voltammetric behavior of dopamine was studied on a glassy carbon electrode (GCE) modified-NiFe(2)O(4) magnetic nanoparticles decorated with multiwall carbon nanotubes. Impedance spectroscopy and cyclic voltammetry were used to characterize the behavior of dopamine at the surface of modified-GCE. The modified electrode showed a synergic effect toward the oxidation of dopamine. The oxidation peak current is increased linearly with the dopamine concentration (at pH7.0) in wide dynamic ranges of 0.05-6.0 and 6.0-100?molL(-1) with a detection limit of 0.02?molL(-1), using differential pulse voltammetry. The selectivity of the method was studied and the results showed that the modified electrode is free from interference of organic compounds especially ascorbic acid, uric acid, cysteine and urea. Its applicability in the determination of dopamine in pharmaceutical, urine samples and human blood serum was also evaluated. The proposed electrochemical sensor has appropriate properties such as high selectivity, low detection limit and wide linear dynamic range when compared with that of the previous reported papers for dopamine detection. PMID:24863201

Ensafi, Ali A; Arashpour, B; Rezaei, B; Allafchian, Ali R

2014-06-01

137

Carbon nanotube cathode with capping carbon nanosheet  

NASA Astrophysics Data System (ADS)

Here, we report a vertically aligned carbon nanotube (VACNT) film capped with a few layer of carbon nanosheet (FLCN) synthesized by chemical vapor deposition using a carbon source from iron phthalocyanine pyrolysis. The square resistance of the VACNT film is significantly reduced from 1500 ?/? to 300 ?/? when it is capped with carbon nanosheet. The VACNT capped with carbon nanosheet was transferred to an ITO glass substrate in an inverted configuration so that the carbon nanosheet served as a flexible transparent electrode at the bottom and the VACNT roots served as emission tips. Because all of the VACNTs start growing from a flat silicon substrate, the VACNT roots are very neat and uniform in height. A field emission test of the carbon nanosheet-capped VACNT film proved that the CNT roots show better uniformity in field emission and the carbon nanosheet cap could also potentially serve as a flexible transparent electrode, which is highly desired in photo-assisted field emission.

Li, Xin; Zhao, Dengchao; Pang, Kaige; Pang, Junchao; Liu, Weihua; Liu, Hongzhong; Wang, Xiaoli

2013-10-01

138

Band-edge exciton states in a single-walled carbon nanotube revealed by magneto-optical spectroscopy in ultrahigh magnetic fields  

NASA Astrophysics Data System (ADS)

We report a high-field magneto-optical study on first and second subband transitions of single-chirality single-walled carbon nanotubes. The ordering and relative energy splitting between bright and dark excitonic states were found to be inverse between the first and second subbands. We verified that the zero-momentum dark singlet exciton lies below the bright exciton for the first subband transitions, while for the second subband transitions, it was found to have higher energy than the bright excitonic state. The effect of this peculiar excitonic structure was found to manifest itself in distinctive Aharonov-Bohm splitting in ultrahigh magnetic fields up to 190 T.

Zhou, Weihang; Sasaki, Tatsuya; Nakamura, Daisuke; Liu, Huaping; Kataura, Hiromichi; Takeyama, Shojiro

2013-06-01

139

Magnetic-fluorescent nanohybrids of carbon nanotubes coated with Eu, Gd Co-doped LaF 3 as a multimodal imaging probe  

Microsoft Academic Search

Multifunctional magnetic-fluorescent nanohybrids were successfully fabricated by a facile layer-by-layer (LBL) self-assembly of in situ generated Eu, Gd co-doped LaF3 nanocrystals (LaF3:Eu:Gd) on the surface of multi-walled carbon nanotubes (MWNTs). Photoluminescence (PL) quenching occurred when LaF3:Eu:Gd nanoparticles were directly coated on the surface of MWNTs. By growth of a SiO2 shell spacer between MWNTs and LaF3:Eu:Gd nanocrystals, we circumvented the

Bingdi Chen; Hui Zhang; Ning Du; Bo Zhang; Yulian Wu; Donglu Shi; Deren Yang

140

Twisting Graphene into Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes are usually described as being rolled up from graphene sheets; this process, however, have never been realized experimentally. We showed that graphene can indeed be transformed into nanotube by twisting [1]. Further, we showed that tube formation can be well-explained within classical theory of elasticity---in fact the very mechanism of tube formation can be observed by twisting a strap from one's backpack (try now!). Furthermore, we showed that nanotube chirality may not only be predicted, but can also be controlled externally. The quantum molecular dynamic simulations at T=300K were achieved thanks to the revised periodic boundary conditions (RPBC) approach [2-3]. The structures similar to simulated have been recently observed experimentally [4]. This novel rote for nanotube formation opens new opportunities in nanomaterial manipulation not restricted to carbon alone. In the presentation, I will describe tube formation, as well as outline the easy and efficient technique for distorted nanostructures simulation, the RPBC approach. [4pt] [1] O. O. Kit et al. arXiv:1108.0048[0pt] [2] P. Koskinen & O. O. Kit PRL 105, 106401 (2010)[0pt] [3] O. O. Kit, L. Pastewka, P. Koskinen PRB 84, 155431 (2011)[0pt] [4] A. Chuvilin et al. Nature Materials 10, 687 (2011)

Kit, Oleg O.; Tallinen, Tuomas; Mahadevan, L.; Timonen, Jussi; Koskinen, Pekka

2012-02-01

141

High frequency carbon nanotube devices  

NASA Astrophysics Data System (ADS)

We investigate high frequency electrical and mechanical performances of carbon nanotube based devices. Using configurations with multiple single-wall nanotubes in parallel, we show that HF nanotube transistors with intrinsic cut-off frequencies as high as 30 GHz can be obtained on rigid substrates. Adapting our process to plastic substrates, we also obtained highly flexible HF transistors showing constant transconductances up to at least 6 GHz, as-measured cut-off frequencies as high as 1 GHz (5-8 GHz after de-embedding) and stable DC performances upon bending. We probed electromechanical properties of individual suspended carbon multiwall nanotubes by using a modified AFM. DC deflection measurements on different devices are in agreement with a continuum model prediction and consistent with a Young's modulus of 0.4 TPa. Preliminary HF measurements on a doubly clamped device showed a resonant frequency of 200MHz consistent with a Young's modulus of 0.43 TPa. This implies that built-in mechanical stress in the case of MWNTs is negligeable.

Goffman, M. F.; Chimot, N.; Mile, E.; Monteverde, M. C.; Bourgoin, J.-P.; Derycke, V.

2008-08-01

142

Multilayer Film Assembly of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

An approach to assemble multilayers of carbon nanotubes on a substrate is presented. Chemical vapor deposition using a transition metal catalyst formulation is used to grow the nanotubes. Results show a bilayer assembly of nanotubes each with a different density of tubes.

Cassell, Alan M.; Meyyappan, M.; Han, Jie; Arnold, J. (Technical Monitor)

2000-01-01

143

Carbon Nanotubes: Synthesis, Properties and Pharmaceutical Applications  

Microsoft Academic Search

Carbon nanotubes (CNTs) are unique cylindrical forms of carbon that have carved a niche in the field of nanomedicine. The possibility of incorporating functionalized carbon nanotubes into cells and the biological milieu offers numerous advantages for potential applications in biology, pharmacology and drug delivery. One of the most promising is the utilization of CNTs as a new carrier system for

Inderbir Singh; Ashish K. Rehni; Pradeep Kumar; Manoj Kumar

2009-01-01

144

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

145

Carbon nanotubes as electron sources  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) are a unique form of carbon filament/fiber in which the graphene walls roll up to form tubes. They can exhibit either metallic-like or semiconductor-like properties. With the graphene walls parallel to the filament axis, nanotubes (single wall metallic-type or multi-wall) exhibit high electrical conductivity at room temperature. This high electrical conductivity allied to their remarkable thermal stability has made CNTs one of the most intensely studied material systems for field emission (FE) applications. In this paper we will describe the growth of multiwall CNTs and their application in a range of field emission based systems including their use in SEM sources, emitters for use in microwave amplifiers and as emitters in field emission based displays (FEDs).

Milne, W. I.; Teo, K. B. K.; Mann, M.; Bu, I. Y. Y.; Amaratunga, G. A. J.; de Jonge, N.; Allioux, M.; Oostveen, J. T.; Legagneux, P.; Minoux, E.; Gangloff, L.; Hudanski, L.; Schnell, J.-P.; Dieumegard, L. D.; Peauger, F.; Wells, T.; El-Gomati, M.

2006-05-01

146

From carbon nanobells to nickel nanotubes  

SciTech Connect

A generic strategy is proposed to prepare one dimensional (1D) metallic nanotubes by using 1D carbon nanostructures as the initial templates. Following the strategy, nickel (Ni) nanotubes are prepared by using carbon nanobells (CNBs) as the initial templates. CNBs are first prepared by microwave plasma enhanced chemical vapor deposition technique. Carbon/nickel core/shell structures are then prepared by electroplating the CNBs in a nickel-Watts electrolytic cell. In the final step, the carbon core is selectively removed by employing hydrogen plasma etching to obtain Ni nanotubes. The mechanism leading to Ni nanotubes is briefly discussed.

Ma, S.; Srikanth, V. V. S. S.; Maik, D.; Zhang, G. Y.; Staedler, T.; Jiang, X. [Institute of Materials Engineering, University of Siegen, Paul-Bonatz-Str. 9-11, 57076 Siegen (Germany)

2009-01-05

147

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

148

Carbon nanotube based battery architecture  

NASA Astrophysics Data System (ADS)

We have fabricated batteries using a random network of carbon nanotubes serving both as the charge collector and the interface with the active components. Due to the high network conductivity and high porosity, such networks, in combination with nanoscale active components, lead to batteries with excellent energy storage characteristics. In addition the devices can be fabricated using a roll-to-roll or inkjet printing process, the essentials of what can be called "printed power."

Kiebele, A.; Gruner, G.

2007-10-01

149

LDRD final report on carbon nanotube composites  

SciTech Connect

Carbon nanotubes and their composites were examined using computational and experimental techniques in order to modify the mechanical and electrical properties of resins. Single walled nanotubes were the focus of the first year effort; however, sufficient quantities of high purity single walled nanotubes could not be obtained for mechanical property investigations. The unusually high electrical conductivity of composites loaded with <1% of multiwalled nanotubes is useful, and is the focus of continuing, externally funded, research.

Cahill, P.A.; Rand, P.B.

1997-04-01

150

Nanomachining carbon nanotubes with ion beams  

NASA Astrophysics Data System (ADS)

We demonstrate the use of 10 and 30 keV focused beams of Ga+ ions to thin, slice, weld, and alter the structure and composition of multiwalled carbon nanotubes at precise locations along the nanotube axis. This strategy of harnessing ion-beam-induced defect generation and doping could be attractive for modulating chemical and electrical properties along the nanotube length, and fabricate nanotube heterostructures and networks for device applications.

Raghuveer, M. S.; Ganesan, P. G.; D'Arcy-Gall, J.; Ramanath, G.; Marshall, M.; Petrov, I.

2004-05-01

151

Nanomachining carbon nanotubes with ion beams  

Microsoft Academic Search

We demonstrate the use of 10 and 30 keV focused beams of Ga+ ions to thin, slice, weld, and alter the structure and composition of multiwalled carbon nanotubes at precise locations along the nanotube axis. This strategy of harnessing ion-beam-induced defect generation and doping could be attractive for modulating chemical and electrical properties along the nanotube length, and fabricate nanotube

M. S. Raghuveer; P. G. Ganesan; J. D'Arcy-Gall; G. Ramanath; M. Marshall; I. Petrov

2004-01-01

152

Single carbon nanotube photonics  

NASA Astrophysics Data System (ADS)

The electronic structure of SWNTs was investigated using the complementary techniques of single molecule photoluminescence spectroscopy and ultrafast optical spectroscopy. We found that photoexcited electrons in SWNTs isolated in surfactant micelles decay through many channels, exhibiting a range of decay times (~200 fs to ~ 120 ps). The magnitude of the longest-lived component in the ultrafast signal specifically depends on resonant excitation, thus suggesting that this lifetime corresponds to the band-edge relaxation time. Fluorescence spectra from single SWNTs are well described by a single, Lorentzian lineshape. However, nanotubes with identical structure fluoresce over a distribution of peak positions and line widths not observed in ensemble studies, caused by localized defects and electrostatic perturbations. Unlike for most other single molecules, for SWNTs the photoluminescence unexpectedly does not show any intensity or spectral fluctuations at 300K. This lack of photoluminescence intensity blinking or bleaching demonstrates that SWNTs have the potential to provide a stable, single molecule infrared photon source, allowing for the exciting possibility of single nanotube integrated photonic devices and biophotonic sensors.

Huang, Libai; Hartschuh, Achim; Pedrosa, Hermenegildo N.; Peterson, Jeffrey; Steiner, Mathias; Novotny, Lukas; Krauss, Todd D.

2005-03-01

153

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

154

Double-Wall Carbon Nanotubes  

Microsoft Academic Search

\\u000a Double-wall carbon nanotubes (DWNTs) are the simplest archetypical\\u000a manifestation of MWNTs and as such combine the outstanding properties of SWNTs\\u000a with the possibility to study concentric intertube interactions with high\\u000a precision. Two complementary routes for the efficient growth of DWNTs are\\u000a discussed. Firstly, SWNTs filled with various carbon sources, such as fullerenes or\\u000a acenes can form inner-shell tubes by a

Rudolf Pfeiffer; Thomas Pichler; Yoong Kim; Hans Kuzmany

155

Aharonov-Bohm effects on optical phonons in carbon nanotubes  

Microsoft Academic Search

Effects of electron-phonon interaction on optical phonons are studied in carbon nanotubes. In metallic nanotubes, the gap due to an Aharonov-Bohm magnetic flux oriented in the tube axis causes a singular behavior in the broadening. In particular, the broadening appears in the transverse mode and diverges when the gap reaches the phonon energy. This Aharonov-Bohm effect can be used for

Kohta Ishikawa; Tsuneya Ando

2007-01-01

156

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

157

Field Enhancement inside Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

There are many investigations on photo-excitations with polarization vector parallel to tube axis (parallel-polarization), compared to it, few studys on those with polarization vector perpendicular to tube axis (cross-polarization) are reported because of early theoretical consideration on electric-field-depolarization effect of nanotubes with cross-polarization [1]. Using dynamical consideration and TDDFT analysis, we herein present the influence of external electric field perpendicular to the axis of semiconductor carbon nanotube (CNT). By adjusting frequency of applied E-field in corresponding wavelength of light from 800nm to 591 nm, the total E-field inside carbon nanotubes has been found to show great change depending on the frequency; incomplete screening and strong enhancement even without including the excitonic effect [2]. The enhancement comes from increase of oscillating amplitude of electron cloud with resonant frequency given by the applied E-field. Also the numerical stability and the satisfaction of energy conservation rule with application of dynamical E-field were numerically checked [3]. This finding should be taken into account in interpreting a measurement of optical response of molecules being encapsulated in CNTs. [1]. H. Ajiki and T. Ando, Physica B 201, 349 (1994) [2]. S. Uryu and T. Ando, Phys. Rev. B 76, 115420 (2007) [3]. Y. Miyamoto and H. Zhang, Phys. Rev. B 77, 165123 (2008)

Zhang, Hong; Miyamoto, Yoshiyuki

2009-03-01

158

Multiwall carbon nanotubes from pyrolysis of tetrahydrofuran  

SciTech Connect

Multiwalled carbon nanotubes have been prepared by pyrolysing tetrahydrofuran (THF) in the presence of nickelocene. Pyrolysis of the precursor mixture has been achieved at temperature as low as 600 deg. C. In this simple approach no carrier gas has been used. The yield of purified carbon nanotubes is found to be more than 65%. Characterization of the as-prepared and purified nanotubes are done by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy and Raman spectra.

Mahanandia, P. [Department of Physics, Indian Institute of Science, Bangalore 560012, Karnataka (India)]. E-mail: pitam@physics.iisc.ernet.in; Vishwakarma, P.N. [Department of Physics, Indian Institute of Science, Bangalore 560012, Karnataka (India); Nanda, K.K. [Material Research Center, Indian Institute of Science, Bangalore 560012 (India); Prasad, V. [Department of Physics, Indian Institute of Science, Bangalore 560012, Karnataka (India); Subramanyam, S.V. [Department of Physics, Indian Institute of Science, Bangalore 560012, Karnataka (India); Dev, S.K. [Material Science Division, BARC, Mumbai 400085 (India); Satyam, P.V. [Institute of Physics, Bhubaneswar 751005 (India)

2006-12-14

159

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

160

Single Carbon Nanotube Transistor at GHz Frequency  

E-print Network

Single Carbon Nanotube Transistor at GHz Frequency J. Chaste,, L. Lechner,£ P. Morfin,, G. Fe operation of top-gated single carbon nanotube transistors. From transmission measurements in the 0.1-1.6 GHz effect transistors (CNT-FETs) are very attractive as ultimate, quantum limited devices. In particular

Plaçais, Bernard

161

Multifunctional Catalysts for Singlewall Carbon Nanotube  

E-print Network

137 7 Multifunctional Catalysts for Singlewall Carbon Nanotube Synthesis T. Guo* 7.1. INTRODUCTION Single-wall carbon nanotubes (SWNTs) are usually produced with the help of metal catalysts that first and then release them in the form of SWNTs. These catalysts therefore must perform several functions in order

Guo, Ting

162

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 and the conducting channel are carbon nanotube networks of different densities and Parylene N is the gate insulator

Gruner, George

163

Carbon nanotube films as electron field emitters  

Microsoft Academic Search

Carbon nanotubes have been recognized as one of the most promising electron field emitters currently available. We review the state of the art of current research on the electron field emission properties of carbon nanotube films and present recent results outlining their potential as field emitters as well as illustrating some current concerns in the research field.

Jean-Marc Bonard; Mirko Croci; Christian Klinke; Ralph Kurt; Olivier Noury; Nicolas Weiss

2002-01-01

164

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

165

Supported Lipid Bilayer/Carbon Nanotube Hybrids  

NASA Astrophysics Data System (ADS)

We form supported lipid bilayers on single-walled carbon nanotubes and use this hybrid structure to probe the properties of lipid membranes and their functional constituents. We first demonstrate membrane continuity and lipid diffusion over the nanotube. A membrane-bound tetanus toxin protein, on the other hand, sees the nanotube as a diffusion barrier whose strength depends on the diameter of the nanotube. Finally, we present results on the electrical detection of specific binding of streptavidin to biotinylated lipids with nanotube field effect transistors. Possible techniques to extract dynamic information about the protein binding events will also be discussed.

Zhou, Xinjian; Moran-Mirabal, Jose; Craighead, Harold; McEuen, Paul

2007-03-01

166

Confocal Microscopy of Bioconjugated Carbon Nanotubes for Biosensor Applications  

Microsoft Academic Search

Carbon nanotubes (CNTs) have many unique properties such as high surface area, hollow cavities, and excellent mechanical and electrical properties. Solubilization and biological functionalization of carbon nanotubes have greatly increased the usage of carbon nanotubes in biomedical applications such as biosensors and nanoprobes. This paper presents biofunctionalization of single wall carbon nanotubes (SWNT) with antibodies, which are specific to insulin-like

Kasif TEKER

167

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

168

Towards chirality-pure carbon nanotubes.  

PubMed

Current as-grown single-walled carbon nanotubes vary in diameter and chirality, which results in variations in their electronic and optical properties. Two approaches have been intensively studied to obtain chirality-pure nanotube structures and thus uniform properties for advanced applications. The first approach involves the post-synthesis separation according to the nanotubes' chiral vectors (n, m), and the second one involves direct synthes of carbon nanotubes with the same (n, m). This paper reviews the efforts along these two directions, with emphasis on the most recent progress of post-synthesis separation and the perspectives of controllable synthesis. PMID:20835436

Zhang, Yani; Zheng, Lianxi

2010-10-01

169

Computer generated holograms for carbon nanotube arrays  

NASA Astrophysics Data System (ADS)

Multiwalled carbon nanotubes are highly diffractive structures in the optical regime. Their metallic character and large scattering cross-section allow their usage as diffractive elements in Fraunhofer holograms. This work elaborates some important features of the far field diffraction patterns produced from periodic arrays of nanotubes. A theoretical approach for the interaction of arrays of nanotubes with light is presented and a computer generated hologram is calculated by means of periodical patterns. Based on the results, fabrication of carbon nanotube arrays (in holographic patterns) was performed. Experimentally measured diffraction patterns were in good agreement with the calculations.

Montelongo, Yunuen; Butt, Haider; Butler, Tim; Wilkinson, Timothy D.; Amaratunga, Gehan A. J.

2013-05-01

170

One-pot, solid-phase synthesis of magnetic multiwalled carbon nanotube/iron oxide composites and their application in arsenic removal.  

PubMed

Carbon nanotubes (CNTs) functionalized with magnetic nanoparticles are attractive for environmental remediation applications due to their high specific surface area conducive for adsorption of water contaminants and the possibility of recovering these nanohybrids after remediation using an external magnetic field. Most of existing methods for synthesizing magnetic iron oxide/CNTs (MIO-CNTs) composites are carried out in the liquid medium and are tedious, uneconomical, and environmentally unfriendly. Herein, we report a one-pot solid-phase route to synthesize MIO-CNTs composites based on pristine CNTs. MIO-CNTs possess a high specific surface area, good dispersibility, and desirable magnetic properties, making them promising as adsorbents for arsenic removal. The maximum arsenic adsorption capacities are 47.41 and 24.05mgg(-)(1) for As(V) and As(III), respectively. These values are among the highest for carbon-based materials. Oxygen-containing groups on the surface of MIO-CNTs play a crucial role in arsenic adsorption. This work is very important for the practical applications of pristine CNTs containing catalyst nanoparticles without the need of purifications. PMID:25151091

Chen, Bo; Zhu, Zhiliang; Ma, Jie; Yang, Mingxuan; Hong, Jun; Hu, Xiaohui; Qiu, Yanling; Chen, Junhong

2014-11-15

171

Preparation and Characterization of Poly(methyl methacrylate)-functionalized Carboxyl Multi-walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

An in situ polymerization process was used to prepare poly (methyl methacrylate) (PMMA)-functionalized carboxyl multi-walled carbon nanotubes using carboxylate carbon nanotubes and methyl methacrylate as reactants and benzoyl peroxide as an initiator agent. The functionalized multi-walled carbon nanotubes were characterized using transmission electron microscope, scanning electron microscope, nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis and Raman. The results indicate that the PMMA chains are covalently linked with the surface of carboxylate carbon nanotubes. The surface morphology is controlled by the content of carboxylate carbon nanotubes in the reactants. The PMMA functionalized multi-walled carbon nanotubes are soluble in deuterated chloroform. The storage modulus and tan? magnitude increase as the content of CCNTs increases up to 0.3%.

Meng, Qing-jie; Zhang, Xing-xiang; Bai, Shi-he; Wang, Xue-chen

2007-12-01

172

Carbon-based sorbents: carbon nanotubes.  

PubMed

Carbon nanotubes (CNTs), as an advanced material, have been widely used in various fields since its discovery in 1991. In recent years, as an excellent adsorption material, the pure and modified CNTs are successfully used for the purification and enrichment of food, medicine, environmental samples and so on. In this review, we focus on the detailed description of different CNTs-based extraction modes such as solid-phase extraction (SPE) (including cartridge and disk SPE, dispersive SPE, and ?-SPE) and solid-phase microextraction (SPME) (including fiber SPME, electrosorption-enhanced SPME, stir bar sorptive extraction, needle trap SPME, and hollow fiber SPME). PMID:24792692

Liang, Xiaojing; Liu, Shujuan; Wang, Shuai; Guo, Yong; Jiang, Shengxiang

2014-08-29

173

Quantum dots conjugated with Fe3O4-filled carbon nanotubes for cancer-targeted imaging and magnetically guided drug delivery.  

PubMed

A novel and specific nanoplatform for in vitro simultaneous cancer-targeted optical imaging and magnetically guided drug delivery is developed by conjugating CdTe quantum dots with Fe(3)O(4)-filled carbon nanotubes (CNTs) for the first time. Fe(3)O(4) is filled into the interior of the CNTs, which facilitates magnetically guided delivery and improves the synergetic targeting efficiency. In comparison with that immobilized on the external surface of CNTs, the magnetite nanocrystals inside the CNTs protect it from agglomeration, enhance its chemical stability, and improve the drug loading capacity. It also avoids magnetic nanocrystals-induced quenching of fluorescence of the quantum dots. The SiO(2)-coated quantum dots (HQDs) attached on the surface of CNTs exhibit favorable fluorescence as the hybrid SiO(2) shells on the QDs surface prevent its fluorescence quenching caused by the CNTs. In addition, the hybrid SiO(2) shells also mitigate the toxicity of the CdTe QDs. By coating transferrin on the surface of the herein modified CNTs, it provides a dual-targeted drug delivery system to transport the doxorubicin hydrochloride (DOX) into Hela cells by means of an external magnetic field. The nanocarrier based on the multifunctional nanoplatform exhibits an excellent drug loading capability of ca. 110%, in addition to cancer-targeted optical imaging as well as magnetically guided drug delivery. PMID:23131026

Chen, Mei-Ling; He, Ye-Ju; Chen, Xu-Wei; Wang, Jian-Hua

2012-11-27

174

Nonlinear viscoelasticity of freestanding and polymer-anchored vertically aligned carbon nanotube foams  

E-print Network

. 111, 113511 (2012) Nano / composite precipitates in Alloy 718 Appl. Phys. Lett. 100, 211913 (2012Nonlinear viscoelasticity of freestanding and polymer-anchored vertically aligned carbon nanotube magnetic field affected vibration response of double single-walled carbon nanotube systems J. Appl. Phys

Jensen, Grant J.

175

CARBON NANOTUBE POLYMER NANOCOMPOSITES FOR ELECTROMECHANICAL SYSTEM APPLICATIONS  

E-print Network

....................................................................... 43 2.4.4 Elastic Modulus of Multi-wall Nanotubes ...................................................... 45 2.4.5 Twist/Torsion Modulus of Carbon Nanotubes ................................................ 49 2.4.6 Twist Modulus of Single...-wall Nanotubes ....................................................... 49 2.4.7 Twist Modulus of Multi-wall Carbon Nanotubes ........................................... 54 2.5 Carbon Nanotori...

Chakrabarty, Arnab

2010-10-12

176

Development of novel molecularly imprinted magnetic solid-phase extraction materials based on magnetic carbon nanotubes and their application for the determination of gatifloxacin in serum samples coupled with high performance liquid chromatography.  

PubMed

A novel composite imprinted material, on the basis of magnetic carbon nanotubes (MCNTs)-incorporated layer using gatifloxacin as a template, methacrylic acid as a functional monomer, and ethylene glycol dimethacrylate as a cross-linker, was successfully synthesized by a surface imprinting technique. Adsorption dynamics and a Scatchard adsorption model were employed to evaluate the adsorption process. The results showed that magnetic carbon nanotubes molecularly imprinted polymers (MCNTs@MIP) displayed a rapid dynamic adsorption and a high adsorption capacity of 192.7 ?g/mg toward GTFX. Applied MCNTs@MIP as a sorbent, a magnetic solid phase extraction method coupled with high performance liquid chromatography (MSPE-HPLC) was developed for the determination of GTFX in serum samples. The recoveries from 79.1±4.8% to 85.3±4.2% were obtained. MCNTs@MIP can not only be collected and separated fast by external magnetic field but also have high surface-to-volume ratio, outstanding mechanical properties and specific recognition toward template molecule. In addition, the MCNTs@MIP could be regenerated, which could be used for five cycles with lost of less than 7.8% of its recovery on average. These analytical results of serum samples display that the proposed method based on MCNTs@MIP is applicable for fast and selective extraction of therapeutic agents from biological fluids. PMID:23290337

Xiao, Deli; Dramou, Pierre; Xiong, Nanqian; He, Hua; Li, Hui; Yuan, Danhua; Dai, Hao

2013-01-25

177

Pushing the limits of carbon nanotube transistors  

NASA Astrophysics Data System (ADS)

Carbon nanotubes are arrangements of carbon atoms in the form of thin, hollow tubes. Their physical and electrical properties have attracted much interest in recent years---carbon nanotubes are among the strongest materials currently known and they can perform both as active and passive components in nanoscale circuits. Their electrical properties are the focus of this thesis. The work presented here shows that carbon nanotube transistors can operate in the gate quantum limit and can be used as high-frequency mixers. In the first experiment, an aqueous electrolyte solution was used as the gate electrode of a carbon nanotube transistor. This approach accomplishes the task of efficiently increasing the electrostatic capacitance between the nanotube and the gate via a thin, high-kappa dielectric (water). The total capacitance is shown to reach the quantum limit where charging is dictated by the energy level spacing in the nanotube. Additionally, the gate coupling is nearly ideal, as found from the subthreshold swing of ˜80 mV. The coupling results in record transconductances of ˜7 muS/nm, a result important to applications of carbon nanotubes as chemical and biological sensors. The second experiment measures the high-frequency properties of carbon nanotube transistors by means of frequency mixing. A dc current results from the response of the device to an ac voltage. The amplitude of the current is measured as a function of the frequency of the input, revealing the existence of a cutoff between 1 and 10 GHz. The origin of the cutoff is not completely understood yet, since it is in order-of-magnitude agreement with the cutoff obtained from the contacts while its value does not seem to vary substantially from device to device, suggesting an external limiting factor. Despite the cutoff, the mixing response was measured up to 50 GHz. This is the highest frequency at which the electrical properties of carbon nanotubes have been measured to date.

Rosenblatt, Sami

178

Testing and characterization of carbon nanotubes as strain sensors  

E-print Network

The potential of using carbon nanotube coated flexible cloth as strain gauges was studied. Samples were prepared by sonicating strips of cloth inside a 1mg/ml carbon nanotube in propylene carbonate solution. A dynamic ...

Diaz, Juan D

2011-01-01

179

Effect of carbon nanotube addition on the tribological behavior of carbon\\/carbon composites  

Microsoft Academic Search

Carbon nanotube composite coatings were applied onto carbon\\/carbon composites to improve wear properties. Carbon nanotubes have been prepared by catalytic pyrolysis of hydrocarbons. The nanotube slurry was prepared by addition of phenolic resin and solvent to infiltrate into C\\/C composites. The nanotube added composites were then carbonized in a nitrogen atmosphere. Ball-on-disc type wear tests were performed to evaluate the

Dae-Soon Lim; Jeong-Wook An; Hwack Joo Lee

2002-01-01

180

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

181

Carbon nanotube heat-exchange systems  

DOEpatents

A carbon nanotube heat-exchange system (10) and method for producing the same. One embodiment of the carbon nanotube heat-exchange system (10) comprises a microchannel structure (24) having an inlet end (30) and an outlet end (32), the inlet end (30) providing a cooling fluid into the microchannel structure (24) and the outlet end (32) discharging the cooling fluid from the microchannel structure (24). At least one flow path (28) is defined in the microchannel structure (24), fluidically connecting the inlet end (30) to the outlet end (32) of the microchannel structure (24). A carbon nanotube structure (26) is provided in thermal contact with the microchannel structure (24), the carbon nanotube structure (26) receiving heat from the cooling fluid in the microchannel structure (24) and dissipating the heat into an external medium (19).

Hendricks, Terry Joseph (Arvada, CO); Heben, Michael J. (Denver, CO)

2008-11-11

182

Towards a carbon nanotube antibody sensor  

E-print Network

This work investigated single-walled carbon nanotube (SWNT)/polymer-protein A complexes for optically reporting antibody concentration via a change in near infrared fluorescent emission after antibody binding. SWNT have ...

Bojö, Peter

2012-01-01

183

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

184

Carbon nanotube interconnects for IC chips  

E-print Network

Carbon nanotubes (CNTs) have been investigated as candidate materials to replace or augment the existing copper-based technologies as interconnects for Integrated Circuit (IC) chips. Being ballistic conductors, CNTs are ...

Anwar Ali, Hashina Parveen

2006-01-01

185

Chemistry in the nanospace of carbon nanotubes.  

PubMed

Owing to the hollow structure of carbon nanotubes, they could be filled with various kinds of molecules, providing opportunities for studying the properties of molecules confined in nanospace. On the one hand, the spatial confinement imparts novel and distinct properties to the encapsulated species from their counterparts in bulk. On the other hand, the properties of the carbon nanotubes are modified as a result of the interaction between the carbon nanotubes and the encapsulated molecules. In this Focus Review, we summarize the recent advances in this field, including structure, phase transition, and chemical transformation of the encapsulated molecules as well as tuning of carbon nanotubes' properties, with special emphasis on the relation between these properties and the size of the confined space. PMID:20229569

Wang, Zhiyong; Shi, Zujin; Gu, Zhennan

2010-05-01

186

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.

187

Carbon nanotube-based field ionization vacuum  

E-print Network

We report the development of a novel micropump architecture that uses arrays of isolated vertical carbon nanotubes (CNT) to field ionize gas particles. The ionized gas molecules are accelerated to and implanted into a ...

Jang, Daniel, M. Eng. Massachusetts Institute of Technology

2012-01-01

188

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

189

Functionalization and applications of carbon nanotubes  

E-print Network

Carbon nanotubes (CNTs) possess a unique set of electrical and mechanical properties and have been used in a variety of applications. In this thesis, we explore strategies to functionalize CNTs as well as applications which ...

Schnorr, Jan M. (Jan Markus)

2012-01-01

190

Nanomechanics of carbon nanotubes BY ANDRAS KIS  

E-print Network

nanotubes (CNTs) are the newest forms of carbon discovered in 1991 by Iijima (1991). Owing-doped semiconducting. The field of their potential applications is immense, including reinforcing elements in high

Zettl, Alex

191

Photonics based on carbon nanotubes  

PubMed Central

Among direct-bandgap semiconducting nanomaterials, single-walled carbon nanotubes (SWCNT) exhibit strong quasi-one-dimensional excitonic optical properties, which confer them a great potential for their integration in future photonics devices as an alternative solution to conventional inorganic semiconductors. In this paper, we will highlight SWCNT optical properties for passive as well as active applications in future optical networking. For passive applications, we directly compare the efficiency and power consumption of saturable absorbers (SAs) based on SWCNT with SA based on conventional multiple quantum wells. For active applications, exceptional photoluminescence properties of SWCNT, such as excellent light-emission stabilities with temperature and excitation power, hold these nanometer-scale materials as prime candidates for future active photonics devices with superior performances. PMID:23803293

2013-01-01

192

Controlled Deposition and Alignment of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

A carbon nanotube (CNT) attraction material is deposited on a substrate in the gap region between two electrodes on the substrate. An electric potential is applied to the two electrodes. The CNT attraction material is wetted with a solution defined by a carrier liquid having carbon nanotubes (CNTs) suspended therein. A portion of the CNTs align with the electric field and adhere to the CNT attraction material. The carrier liquid and any CNTs not adhered to the CNT attraction material are then removed.

Smits, Jan M. (Inventor); Wincheski, Russell A. (Inventor); Patry, JoAnne L. (Inventor); Watkins, Anthony Neal (Inventor); Jordan, Jeffrey D. (Inventor)

2012-01-01

193

Ballistic resistance capacity of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes have high strength, light weight and excellent energy absorption capacity and therefore have great potential applications in making antiballistic materials. By examining the ballistic impact and bouncing-back processes on carbon nanotubes, this investigation shows that nanotubes with large radii withstand higher bullet speeds and the ballistic resistance is the highest when the bullet hits the centre of the CNT; the ballistic resistance of CNTs will remain the same on subsequent bullet strikes if the impact is after a small time interval.

Mylvaganam, Kausala; Zhang, L. C.

2007-11-01

194

Immersing carbon nanotubes in cold atomic gases  

NASA Astrophysics Data System (ADS)

We investigate the sympathetic relaxation of a free-standing, vibrating carbon nanotube that is mounted on an atom chip and is immersed in a cloud of ultracold atoms. Gas atoms colliding with the nanotube excite phonons via a Casimir-Polder potential. We use Fermi's golden rule to estimate the relaxation rates for relevant experimental parameters and develop a fully dynamic theory of relaxation for the multimode phononic field embedded in a thermal atomic reservoir. Based on currently available experimental data, we identify the relaxation rates as a function of atom density and temperature that are required for sympathetic ground-state cooling of carbon nanotubes.

Weiß, C. T.; Mironova, P. V.; Fortágh, J.; Schleich, W. P.; Walser, R.

2013-10-01

195

Doped Carbon Nanotubes: Synthesis, Characterization and Applications  

Microsoft Academic Search

\\u000a Various applications of carbon nanotubes require their chemical modification in\\u000a order to tune\\/control their physicochemical properties. One way for achieving this\\u000a control is by carrying out doping processes through which atoms and molecules\\u000a interact (covalently or noncovalently) with the nanotube surfaces. The aim of this\\u000a chapter is to emphasize the importance of different types of doping in carbon\\u000a nanotubes (single-,

Mauricio Terrones; Antonio G. Souza Filho; Apparao M. Rao

196

Interfaces Between Carbon Nanotubes and Nickel Nanoparticles in Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) filled with metals can be used in capacitors, sensors, rechargeable batteries, and so on. Their interface significantly affects the properties of the composites. Here, we show that three kinds of interfaces between crystalline Ni and CNTs exist, namely, ordered, distorted, and disordered. They presented lattice states of Ni atoms near the interface, whereas the (111)Ni plane was parallel to the CNTs' surface and appeared apart in a smaller or bigger angle. The coherent face-centered cubic (f.c.c)/hexagonal close-packed structure (h.c.p) boundary was formed between the crystalline Ni and CNTs at the ordered interface, in which the match was (111)Ni//(0001)Carbon. We suggested a dislocation model for the coherent interface. The model explained why the angle between (200)Ni and the CNTs' inner surface was 52.9° rather than the theoretical value of 54.75°. The (1)/(2)[11\\bar {1}] dislocation was formed to fit the coherent relationship. Thus, Ni lattice shrinkage occurred. Further study indicated that the formation mechanism of crystalline Ni in CNTs was through heterogeneous nucleation on the inner wall surface and growth of the crystal nucleus.

Liu, Bai; Liu, Lirui

2013-12-01

197

Method for nano-pumping using carbon nanotubes  

DOEpatents

The present invention relates generally to the field of nanotechnology, carbon nanotubes and, more specifically, to a method and system for nano-pumping media through carbon nanotubes. One preferred embodiment of the invention generally comprises: method for nano-pumping, comprising the following steps: providing one or more media; providing one or more carbon nanotubes, the one or more nanotubes having a first end and a second end, wherein said first end of one or more nanotubes is in contact with the media; and creating surface waves on the carbon nanotubes, wherein at least a portion of the media is pumped through the nanotube.

Insepov, Zeke (Darien, IL); Hassanein, Ahmed (Bolingbrook, IL)

2009-12-15

198

Near-infrared magneto-optical study of excitonic states in single-walled carbon nanotubes under ultra-high magnetic fields  

NASA Astrophysics Data System (ADS)

Singlet excitonic states at the first subband-edge in single-walled carbon nanotubes (SWCNTs) have been studied through near-infrared magneto-absorption spectroscopy under magnetic fields to 105.9 T. Well-resolved absorption spectra of stretch-aligned SWCNT(CoMoCAT)-gelatin films were obtained above 100 T. By the application of magnetic fields in parallel to the alignment of SWCNTs, peak shift toward the lower energy was observed for (8, 4) and (7, 6) tubes and the opposite behavior was observed for (7, 5) and (6, 5) tubes. Above 28.8 T, new peaks emerged at the higher energy side of the peak for the (8, 4) and (7, 6) tubes, and at the lower energy side of the peaks for the (7, 5) and (6, 5) tubes. The magnetic splitting between the existing peak and the new peak was symmetric for every tube, which is in line with the energy splitting due to the Aharonov-Bohm effect. Judging from the energetic positions where the new peaks emerged, the singlet dark excitonic state locates at the lower energy than the singlet bright one in the (7, 5) and (6, 5) tubes while it is suggested strongly that the bright one locates at the lower energy in the (8, 4) and (7, 6) tubes.

Yokoi, H.; Effendi, Mukhtar; Minami, N.; Takeyama, S.

2011-12-01

199

Multi-walled carbon nanotube modified dummy-template magnetic molecularly imprinted microspheres as solid-phase extraction material for the determination of polychlorinated biphenyls in fish.  

PubMed

Novel multi-walled carbon nanotube modified dummy-template molecularly imprinted microspheres (MWCNTs@DMMIPs) were successfully synthesized as adsorbents for six kinds of polychlorinated biphenyls (PCBs). MWCNTs@DMMIPs were prepared by a surface molecular imprinting technique. Core-shell Fe3 O4 @SiO2 nanoparticles were employed as magnetic support. 3,4-Dichlorobenzene acetic acid was used as a dummy template instead of PCBs, methacrylic acid was used as functional monomer and ethylene glycol dimethacrylate was used as the cross-linker. The resulting absorbent was characterized by various methods. The adsorbent was employed for extracting PCBs and exhibited good selectivity and high adsorption efficiency. Furthermore, it was reusable and capable of magnetic separation. Adsorption kinetics fit well with a pseudo-second-order kinetic equation and also exhibited a three-stage intra-particle diffusion model. The Freundlich model was used to describe the adsorption isotherms. The materials were successfully applied to the magnetic dispersive solid-phase extraction of six kinds of PCBs followed by gas chromatography with mass spectrometry determination in fish samples, the limit of detection of six kinds of PCBs were 0.0028-0.0068 ?g/L and spiked recoveries ranged between 73.41 and 114.21%. The prepared adsorbent was expected to be a new material for the removal and recovery of PCBs from contaminated foods. PMID:24737691

Du, Xiaowen; Lin, Saichai; Gan, Ning; Chen, Xidong; Cao, Yuting; Li, Tianhua; Zhan, Pan

2014-07-01

200

Preparation, characterization and adsorption properties of chitosan modified magnetic graphitized multi-walled carbon nanotubes for highly effective removal of a carcinogenic dye from aqueous solution  

NASA Astrophysics Data System (ADS)

Novel chitosan-modified magnetic graphitized multi-walled carbon nanotubes (CS-m-GMCNTs) were synthesized via a suspension cross-linking method. Composition, morphology and magnetic properties of as-prepared CS-m-GMCNTs were characterized by XRD, SEM-EDS, BET and VSM. The large saturation magnetization (12.27 emu g-1) allows fast separation of CS-m-GMCNTs from treated aqueous solution. The adsorption of congo red (CR) on CS-m-GMCNTs was strongly dependent on pH, temperature of the aqueous phase and adsorbent dosage. Up to 100 and 94.58% color removal could be achieved in 100 min contact time with 10 and 50 mg L-1 of initial concentrations, respectively. The adsorption capacity of CR onto CS-m-GMCNTs could reach 262.9 mg g-1. The pseudo-second-order kinetic model with high correlation coefficients (R2 > 0.999) was suitable to describe the process of CR adsorption onto CS-m-GMCNTs. The Langmuir model fitted the adsorption isotherm data better than the Freundlich model. Values of thermodynamic parameters (?G°, ?H° and ?S°) indicated that the adsorption process was strongly dependent on temperature of the aqueous phase, and spontaneous and endothermic process in nature. Therefore, CS-m-GMCNTs adsorbent displays main advantages of excellent dispersion, convenience separation and high adsorption capacity, which implies their potential application in the environmental cleanup.

Zhu, HuaYue; Fu, YongQian; Jiang, Ru; Yao, Jun; Liu, Li; Chen, YanWen; Xiao, Ling; Zeng, GuangMing

2013-11-01

201

Synthesis and Applications of Carbon Nanotubes and Graphene carbon nanotube, graphene, CVD growth, application  

E-print Network

Synthesis and Applications of Carbon Nanotubes and Graphene carbon nanotube, graphene, CVD growth] SWNT ACCVD CVD SWNT CVD SWNT #12; SWNT CVD SWNT CVD SWNT nm SWNT CVD CVD Co Fe 900 1100 C SWNT MWNT SWNT SWNT HiPco [5] CoMoCAT [6] ACCVD ACCVD 500900 C SWNT CVD [1] 1

Maruyama, Shigeo

202

Underwater sound generation using carbon nanotube projectors.  

PubMed

The application of solid-state fabricated carbon nanotube sheets as thermoacoustic projectors is extended from air to underwater applications, thereby providing surprising results. While the acoustic generation efficiency of a liquid immersed nanotube sheet is profoundly degraded by nanotube wetting, the hydrophobicity of the nanotube sheets in water results in an air envelope about the nanotubes that increases pressure generation efficiency a hundred-fold over that obtained by immersion in wetting alcohols. Due to nonresonant sound generation, the emission spectrum of a liquid-immersed nanotube sheet varies smoothly over a wide frequency range, 1-10(5) Hz. The sound projection efficiency of nanotube sheets substantially exceeds that of much heavier and thicker ferroelectric acoustic projectors in the important region below about 4 kHz, and this performance advantage increases with decreasing frequency. While increasing thickness by stacking sheets eventually degrades performance due to decreased ability to rapidly transform thermal energy to acoustic pulses, use of tandem stacking of separated nanotube sheets (that are addressed with phase delay) eliminates this problem. Encapsulating the nanotube sheet projectors in argon provided attractive performance at needed low frequencies, as well as a realized energy conversion efficiency in air of 0.2%, which can be enhanced by increasing the modulation of temperature. PMID:20507157

Aliev, Ali E; Lima, Marcio D; Fang, Shaoli; Baughman, Ray H

2010-07-14

203

Shell buckling of individual multiwalled carbon nanotubes using nanoindentation  

E-print Network

Shell buckling of individual multiwalled carbon nanotubes using nanoindentation J. F. Waters, P. R individual multiwalled carbon nanotubes were axially compressed using a nanoindenter and the critical shell in individual, well-characterized multiwalled carbon nanotubes, using nanoindentation. The multiwalled carbon

Suresh, Subra

204

Magneto-optical spectra of carbon nanotubes: effect of Aharonov–Bohm flux on depolarization effect  

Microsoft Academic Search

Optical absorption spectra of carbon nanotubes in a magnetic field perpendicular to the tube axis, are calculated for parallel polarization. A depolarization field is induced by Aharonov–Bohm flux, which reduces the lowest peak dramatically.

Hiroshi Ajiki

2002-01-01

205

Magnetic enhancement of thermal conductivity in coppercarbon nanotube composites produced by electroless plating, freeze drying, and spark plasma sintering  

E-print Network

Available online 9 April 2012 Keywords: Magnetic Carbon nanotube Spark plasma sintering Thermal conductivityMagnetic enhancement of thermal conductivity in copper­carbon nanotube composites produced by electroless plating, freeze drying, and spark plasma sintering Evan Khaleghi a, , Milton Torikachvili b , Marc

Meyers, Marc A.

206

Optical Signatures of the Aharonov-Bohm Phase in Single-Walled Carbon Nanotubes  

Microsoft Academic Search

We report interband magneto-optical spectra for single-walled carbon nanotubes in high magnetic fields up to 45 tesla, confirming theoretical predictions that the band structure of a single-walled carbon nanotube is dependent on the magnetic flux phi threading the tube. We have observed field-induced optical anisotropy as well as red shifts and splittings of absorption and photoluminescence peaks. The amounts of

Sasa Zaric; Gordana N. Ostojic; Junichiro Kono; Jonah Shaver; Valerie C. Moore; Michael S. Strano; Robert H. Hauge; Richard E. Smalley; Xing Wei

2004-01-01

207

Multiphase fluids confined in carbon nanotubes  

NASA Astrophysics Data System (ADS)

The dynamics of liquid attoliter volumes contained in carbon nanotubes is investigated theoretically and experimentally. The experiments employ electron microscopy to visualize multiphase fluids in real time with spatial resolution approaching 1nm. The hydrophilic nanochannels studied include hydrothermally synthesized, CVD and commercially produced carbon nanotubes with inner diameters in the range 5-300 nm and wall thickness ranging from 1 nm to 40 nm. Dynamic phenomena are presented for aqueous fluids contained in closed-end nanotubes, and pure water condensing inside open-end carbon nanotubes. Some examples are given on filling nanotube channels with fluids impregnated with solid particles. A theoretical model formulated using a continuum approach, combines temperature-dependent mass diffusion with intermolecular (Lennard-Jones) interactions in the fluid bulk, as well as in the vicinity of the carbon walls. Several axisymmetric cases are considered, and comparisons between theoretical predictions and experimental data are performed. The current study shows the potential of using nanotube channels for understanding fluid behavior at the nanoscale.

Megaridis, Constantine; Gogotsi, Yury; Yarin, Alexander

2005-11-01

208

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

209

Synthesis and fluid interaction of ultra long carbon nanotubes  

E-print Network

The successful integration for carbon nanotubes in future electronic applications relies on advances in their synthesis. In this work optimization of growth parameters was conducted to obtain ultra long carbon nanotubes. ...

Hofmann, Mario

2009-01-01

210

Analyzing manufacturing methods of carbon nanotubes for commercialization  

E-print Network

This research explores the history and structure of carbon nanotubes and the current technologies and methods available for synthesizing, purifying, and assembling carbon nanotubes. Furthermore, the current state of ...

Dee, H. Devin (Herbert Devin)

2013-01-01

211

Selective Functionalization of Carbon Nanotubes: Part II  

NASA Technical Reports Server (NTRS)

An alternative method of low-temperature plasma functionalization of carbon nanotubes provides for the simultaneous attachment of molecular groups of multiple (typically two or three) different species or different mixtures of species to carbon nanotubes at different locations within the same apparatus. This method is based on similar principles, and involves the use of mostly the same basic apparatus, as those of the methods described in "Low-Temperature Plasma Functionalization of Carbon Nanotubes" (ARC-14661-1), NASA Tech Briefs, Vol. 28, No. 5 (May 2004), page 45. The figure schematically depicts the basic apparatus used in the aforementioned method, with emphasis on features that distinguish the present alternative method from the other. In this method, one exploits the fact that the composition of the deposition plasma changes as the plasma flows from its source in the precursor chamber toward the nanotubes in the target chamber. As a result, carbon nanotubes mounted in the target chamber at different flow distances (d1, d2, d3 . . .) from the precursor chamber become functionalized with different species or different mixtures of species. In one series of experiments to demonstrate this method, N2 was used as the precursor gas. After the functionalization process, the carbon nanotubes from three different positions in the target chamber were examined by Fourier-transform infrared spectroscopy to identify the molecular groups that had become attached. On carbon nanotubes from d1 = 1 cm, the attached molecular groups were found to be predominantly C-N and C=N. On carbon nanotubes from d2 = 2.5 cm, the attached molecular groups were found to be predominantly C-(NH)2 and/or C=NH2. (The H2 was believed to originate as residual hydrogen present in the nanotubes.) On carbon nanotubes from d3 = 7 cm no functionalization could be detected - perhaps, it was conjectured, because this distance is downstream of the plasma source, all of the free ions and free radicals of the plasma had recombined into molecules.

Meyyappan, Meyya; Khare, Bishun

2010-01-01

212

Magnetic multi-wall carbon nanotube nanocomposite as an adsorbent for preconcentration and determination of lead (II) and manganese (II) in various matrices.  

PubMed

Magnetic multi-wall carbon nanotube (MMWCNT) nanocomposite was synthesized and used as an adsorbent for preconcentration and determination of lead (II) and manganese (II). The properties of MMWCNT were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Energy dispersive X-ray spectrometry (EDS) and fourier transform infrared spectrophotometer (FT-IR). This adsorbent was found to be advantageous over conventional solid phase extraction (SPE) in terms of operational simplicity and low time-consuming. MMWCNT, carrying target metals, was easily separated from the aqueous solutions with the help of an external magnet; so, no filtration or centrifugation was necessary. After extraction and collection of MMWCNT, the adsorbed analytes were eluted and analyzed by flame atomic absorption spectrometry (FAAS). Experiments were carried out to investigate the influence of different sorption/desorption parameters. Under the optimized conditions, detection limits and enhancement factors of the proposed method for Pb and Mn were 1.0 and 0.6 µg L(-1), 390 and 697 respectively. The presented procedure was successfully applied for determination of Pb(II) and Mn (II) contents in lipstick, rice samples and accuracy was evaluated analyzing a certified reference material Seronorm(™) Urine LOT NO2525. PMID:24054657

Daneshvar Tarigh, Ghazale; Shemirani, Farzaneh

2013-10-15

213

Carbon Nanotube Tower-Based Supercapacitor  

NASA Technical Reports Server (NTRS)

A supercapacitor system, including (i) first and second, spaced apart planar collectors, (ii) first and second arrays of multi-wall carbon nanotube (MWCNT) towers or single wall carbon nanotube (SWCNT) towers, serving as electrodes, that extend between the first and second collectors where the nanotube towers are grown directly on the collector surfaces without deposition of a catalyst and without deposition of a binder material on the collector surfaces, and (iii) a porous separator module having a transverse area that is substantially the same as the transverse area of at least one electrode, where (iv) at least one nanotube tower is functionalized to permit or encourage the tower to behave as a hydrophilic structure, with increased surface wettability.

Meyyappan, Meyya (Inventor)

2012-01-01

214

Preparation, Characterization, and Evaluation of Immuno Carbon Nanotubes  

Microsoft Academic Search

.  Single-walled and multiple-walled carbon nanotubes were functionalized with bovine serum albumin protein to attain aqueous\\u000a solubility and biocompatibility. These aqueous soluble carbon nanotube-protein conjugates were further conjugated with pathogen-specific\\u000a antibody to form immuno carbon nanotubes. The experimental details on the conjugation and results from the characterization\\u000a of the conjugates are presented. The potential of these immuno carbon nanotubes in the

Yi Lin; Tara Elkin; Shelby Taylor; Lingrong Gu; Bailin Chen; Lucia Monica Veca; Bing Zhou; Hua Yang; Jessica Brown; Ronalda Joseph; Erin Jones; Xiuping Jiang; Ya-Ping Sun

2006-01-01

215

Raman spectroscopy of polystyrene nanofibers—Multiwalled carbon nanotubes composites  

NASA Astrophysics Data System (ADS)

Raman spectroscopy investigations of nanofibers of polystyrene loaded with various amounts of multiwalled carbon nanotubes are reported. The modifications of the main Raman bands (D and G) of multiwalled carbon nanotubes due to their dispersion in polystyrene demonstrates and quantifies the stress transfer from the polymeric nanofiber matrix (polystyrene) to multiwalled carbon nanotubes. TGA data show an increase of the thermal stability of polystyrene nanofibers upon the loading with multiwalled carbon nanotubes, conforming Raman data.

Chipara, Dorina M.; Macossay, Javier; Ybarra, Ana V. R.; Chipara, A. C.; Eubanks, Thomas M.; Chipara, Mircea

2013-06-01

216

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

217

Raman spectroscopy of single wall carbon nanotubes  

E-print Network

A single wall carbon nanotube (SWNT) is a new form of carbon, whose atomic arrangement is equivalent to a graphene sheet rolled into a cylinder in a seamless way. The typical diameter of a SWNT ranges from 0.6 nm to several ...

Son, HyungBin, 1981-

2008-01-01

218

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

219

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

220

Thermal Transport in Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Recent advances in nanostructure technology have made it possible to create small devices at the nanoscale. Carbon nanotubes (CNT's) are among the most exciting building blocks of nanotechnology. Their versatility and extremely desirable properties for electronic and other devices have driven intense research and development efforts in recent years. A review of electrical and thermal conduction of the structures will be presented. The theoretical investigation is mainly based on molecular dynamics. Green Kubo relation is used for the study of thermal conductivity. Results include kinetic energy, potential energy, heat flux autocorrelation function, and heat conduction of various CNT structures. Most of the computation and simulation has been conducted on the Beowulf cluster at Ball State University. Various software packages and tools such as Visual Molecular Dynamics (VMD), Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), and NanoHUB, the open online resource at Purdue University have been used for the research. The work has been supported by the Indiana Academy of Science Research Fund, 2010-2011.

Christman, Jeremy; Moore, Andrew; Khatun, Mahfuza

2011-10-01

221

Does water dope carbon nanotubes?  

PubMed

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. PMID:25362328

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

2014-10-28

222

Elastomer Reinforced with Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

Elastomers are reinforced with functionalized, single-walled carbon nanotubes (SWNTs) giving them high-breaking strain levels and low densities. Cross-linked elastomers are prepared using amine-terminated, poly(dimethylsiloxane) (PDMS), with an average molecular weight of 5,000 daltons, and a functionalized SWNT. Cross-link densities, estimated on the basis of swelling data in toluene (a dispersing solvent) indicated that the polymer underwent cross-linking at the ends of the chains. This thermally initiated cross-linking was found to occur only in the presence of the aryl alcohol functionalized SWNTs. The cross-link could have been via a hydrogen-bonding mechanism between the amine and the free hydroxyl group, or via attack of the amine on the ester linage to form an amide. Tensile properties examined at room temperature indicate a three-fold increase in the tensile modulus of the elastomer, with rupture and failure of the elastomer occurring at a strain of 6.5.

Hudson, Jared L.; Krishnamoorti, Ramanan

2009-01-01

223

Formation of Carbon Nanotubes in a Microgravity Environment  

NASA Technical Reports Server (NTRS)

Even though nanotube science has become one of the worlds most rapidly advancing areas of research, very little is known about the processes involved in nanotube synthesis. To study the formation of carbon nanotubes in an environment unhindered by the buoyancy induced flows generated by the high temperatures necessary to vaporize carbon and grow nanotubes, we have designed a miniature carbon arc apparatus that can produce carbon nanotubes under microgravity conditions. During the first phase of this project, we designed, built, and successfully tested the mini carbon arc in both 1g and 2.2 sec drop tower microgravity conditions. We have demonstrated that microgravity can eliminate the strong convective flows from the carbon arc and we have successfully produced single-walled carbon nanotubes in microgravity. We believe that microgravity processing will allow us to better understand the nanotube formation process and eventually allow us to grow nanotubes that are superior to ground-based production.

Alford, J. M.; Mason, G. R.; Feikema, D. A.

2001-01-01

224

Interactions Between Cultured Neurons and Carbon Nanotubes: A Nanoneuroscience Vignette  

PubMed Central

Carbon nanotubes, owing to their electrical, chemical, mechanical, and thermal properties, are one of the most promising nanomaterials for the electronics, computer, and aerospace industries. More recently, these unique materials are finding their niche in neuroscience. Here, we discuss the use of carbon nanotubes as scaffolds for neuronal growth. The chemical properties of carbon nanotubes can be systematically varied by attaching different functional groups. Such functionalized carbon nanotubes can be used to control the outgrowth and branching pattern of neuronal processes. We also discuss electrical interactions between neurons and carbon nanotubes. The electrical properties of nanotubes can provide a mechanism to monitor or stimulate neurons through the scaffold itself. The ease of which carbon nanotubes can be patterned makes them attractive for studying the organization of neural networks and has the potential to develop new devices for neural prosthesis. We note that additional toxicity studies of carbon nanotubes are necessary so that exposure guidelines and safety regulations can be set. PMID:19865604

Sucapane, Antonietta; Cellot, Giada; Prato, Maurizio; Giugliano, Michele; Parpura, Vladimir; Ballerini, Laura

2009-01-01

225

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

226

Mechanics of Carbon Nanotubes and their Polymer Composites  

NASA Technical Reports Server (NTRS)

Contents include the folloving: carbon nanotube (CNT): structures, application of carbon nanotubes, simulation method, Elastic properties of carbon nanotubes, yield strain of CNT, yielding under tensile stress, yielding: strain-rate and temperature dependence, yield strain under tension, yielding at realistic conditions, nano fibers, polymer CNT composite, force field, density dependency on temperature, diffusion coefficients, young modulus, and conclusions.

Wei, Chenyu; Cho, K. J.; Srivastava, Deepak; Tang, Harry (Technical Monitor)

2002-01-01

227

Chemical modification of carbon nanotubes and preparation of polystyrene\\/carbon nanotubes composites  

Microsoft Academic Search

Single-walled carbon nanotubes (SWNTs) have been chemically modified through the formation of carboxylic acid functionalities\\u000a or by grafting octadecylamine and polystyrene onto them. We purified SWNTs with nitric acid to remove some remaining catalysts\\u000a and amorphous carbon materials. After purification, we broke the carbon nanotubes and shortened their lengths by using a 3?1\\u000a mixture of concentrated sulfuric acid and nitric

Hyeong Taek Ham; Chong Min Koo; Sang Ouk Kim; Yeong Suk Choi; In Jae Chung

2004-01-01

228

Encapsulation of lanthanum carbide in carbon nanotubes and carbon nanoparticles  

Microsoft Academic Search

The morphologies of lanthanum-filled carbon nanotubes and nanoparticles, made by arc-discharging carbon-La2O3 composites, were examined with high-resolution transmission electron microscopy and selected-area electron diffraction technique. The HRTEM images and corresponding SARD patterns obtained from the arc-discharge product confirmed that ?-LaC2 nanocrystals, most of which are single crystals, had been formed within the nanotubes and nanoparticles. The encapsulated ?-LaC2 crystals showed

Mingqui Liu; John M. Cowley

1995-01-01

229

Carbon nanotube suspensions, dispersions, & composites  

NASA Astrophysics Data System (ADS)

Carbon Nanotubes (CNTs) are amazing structures that hold the potential to revolutionize many areas of scientific research. CNTs can be behave both as semiconductors and metals, can be grown in highly ordered arrays and patterns or in random orientation, and can be comprised of one graphene cylinder (single wall nanotube, SWNT) or several concentric graphene cylinders (multi-wall nanotube, MWNT). Although these structures are usually only a few nanometers wide, they can be grown up to centimeter lengths, and in massive quantities. CNTs can be produced in a variety of processes ranging from repeated combustion of organic material such as dried grass, arc-discharge with graphite electrodes, laser ablation of a graphitic target, to sophisticated chemical vapor deposition (CVD) techniques. CNTs are stronger than steel but lighter than aluminum, and can be more conductive than copper or semiconducting like silicon. This variety of properties has been matched by the wide variety of applications that have been developed for CNTs. Many of these applications have been limited by the inability of researchers to tame these structures, and incorporating CNTs into existing technologies can be exceedingly difficult and prohibitively expensive. It is therefore the aim of the current study to develop strategies for the solution processing and deposition of CNTs and CNT-composites, which will enable the use of CNTs in existing and emerging technologies. CNTs are not easily suspended in polar solvents and are extremely hydrophobic materials, which has limited much of the solution processing to organic solvents, which also cannot afford high quality dispersions of CNTs. The current study has developed a variety of aqueous CNT solutions that employ surfactants, water-soluble polymers, or both to create suspensions of CNTs. These CNT 'ink' solutions were deposited with a variety of techniques that have afforded many interesting structures, both randomly oriented as well as highly ordered CNT architectures, and electroactive devices such as sensors were subsequently produced from these materials. The aqueous solutions developed contain some of the longest CNTs to be suspended in water, which have many benefits for electronic and mechanical properties of the resultant composite materials. A non-covalent alternative to standard oxidative acid treatment was developed that has an equal ability to suspend CNTs in various solvents, but does not damage the CNT structure like the covalent functionalization with acids. This strategy has the potential to supplant a widely used method with improved CNT properties, faster and safer processing, and reduced environmental impact of waste materials. The results of this work also suggest that the conductivity of the CNTs may actually be improved by the processing, maximizing the utility if these materials. Electroactive devices have been successfully developed that exploit the unique electrical and physical properties of CNTs. Sensitive moisture sensors, which can possibly out-perform existing part per million sensors, have been developed with CNT inks and alumina nanoparticles. These sensor materials can be easily deposited on a wide variety of substrate materials and have an increased resistance to fouling compared to mesoporous sensors currently available. Electric double-layer supercapacitors based on novel cellulose-CNT composites have also been developed, and have commercially viable capacitance values, which make them a competitive technology with applications such as cell phones, computers, hand-held electronics, and possibly even electric automobiles. These supercapacitors employ less hazardous materials than competing technologies, and the ease of production of these devices could enable large-scale production of these materials.

Simmons, Trevor John

230

Piezoresistive effect in carbon nanotube fibers.  

PubMed

The complex structure of the macroscopic assemblies of carbon nanotubes and variable intrinsic piezoresistivity of nanotubes themselves lead to highly interesting piezoresistive performance of this new type of conductive material. Here, we present an in-depth study of the piezoresistive effect in carbon nanotube fibers, i.e., yarnlike assemblies made purely of aligned carbon nanotubes, which are expected to find applications as electrical and electronic materials. The resistivity changes of carbon nanotube fibers were measured on initial loading, through the elastic/plastic transition, on cyclic loading and on stress relaxation. The various regimes of stress/strain behavior were modeled using a standard linear solid model, which was modified with an additional element in series to account for the observed creep behavior. On the basis of the experimental and modeling results, the origin of piezoresistivity is discussed. An additional effect on the resistivity was found as the fiber was held under load which led to observations of the effect of humidity and the associated water adsorption level on the resistivity. We show that the equilibrium uptake of moisture leads to the decrease in gauge factor of the fiber decrease, i.e., the reduction in the sensitivity of fiber resistivity to loading. PMID:25337627

Lekawa-Raus, Agnieszka; Koziol, Krzysztof K K; Windle, Alan H

2014-11-25

231

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

232

Determination of mechanical properties of carbon nanotubes and vertically aligned carbon nanotube forests using nanoindentation  

Microsoft Academic Search

Vertically aligned carbon nanotubes (VACNT) have been a recent subject of intense investigation due to the numerous potential applications of VACNTs ranging from field emission and vacuum microelectronic devices to the creation of super-hydrophobic surfaces and as a source of well defined CNTs. In this paper, a new method to determine the mechanical properties of VACNT and constituent nanotubes using

H. J. Qi; K. B. K. Teo; K. K. S. Lau; M. C. Boyce; W. I. Milne; J. Robertson; K. K. Gleason

2003-01-01

233

Selective microwave absorption of iron-rich carbon nanotube composites.  

PubMed

We report on high selectivity of microwave absorption by controlling the concentration of carbon nanotubes in polymer composites and matching the dielectric loss and magnetic loss through encapsulation of crystalline Fe nanorods inside nanotubes. The reflection loss reached more than 10 dB (> 90% absorption) by loading nanotubes at concentrations of 1 wt% to 10 wt% into the composites, and the frequencies corresponding to the maximum loss can be tailored throughout the range of 2 to 18 GHz by changing the concentration. A maximum absorption capability (75 dB x GHz) was observed at a CNT loading of about 4.5 wt%. The crystalline structure of encapsulated Fe nanorods can be modified to enhance the reflection loss. Control of absorption selectivity by modifying the structure and concentration of nanoscale fillers could facilitate potential higher-frequency applications (e.g., radar absorbing) of nanocomposites. PMID:20355578

Gui, Xuchun; Wang, Kunlin; Cao, Anyuan; Wei, Jinquan; Lv, Ruitao; Kang, Feiyu; Shu, Qinke; Jia, Yi; Wu, Dehai

2010-03-01

234

Anomalous aharonov-bohm gap oscillations in carbon nanotubes.  

PubMed

The gap oscillations caused by a magnetic flux penetrating a carbon nanotube represent one of the most spectacular observations of the Aharonov-Bohm effect at the nanoscale. Our understanding of this effect is, however, based on the assumption that the electrons are strictly confined on the tube surface, on trajectories that are not modified by curvature effects. Using an ab initio approach based on density functional theory, we show that this assumption fails at the nanoscale inducing important corrections to the physics of the Aharonov-Bohm effect. Curvature effects and electronic density that is spilled out of the nanotube surface are shown to break the periodicity of the gap oscillations. We predict the key phenomenological features of this anomalous Aharonov-Bohm effect in semiconductive and metallic tubes and the existence of a large metallic phase in the low flux regime of multiwalled nanotubes, also suggesting possible experiments to validate our results. PMID:21805987

Sangalli, Davide; Marini, Andrea

2011-10-12

235

The effect of carbon nanotube growing on carbon fibers on the microstructure of the pyrolytic carbon and the thermal conductivity of carbon\\/carbon composites  

Microsoft Academic Search

Carbon nanotubes were prepared on the surface of carbon fibers in a unidirectional carbon preform and then chemical vapor deposition was used to densify the preform to get a modified carbon\\/carbon composite. The effects of carbon nanotubes on the microstructure of the pyrolytic carbon and the thermal conductivity of the composite were investigated. Results show that carbon nanotubes on the

Jie Chen; Xiang Xiong; Peng Xiao

2009-01-01

236

Laser ablative synthesis of carbon nanotubes  

DOEpatents

An improved method for the production of single walled carbon nanotubes that utilizes an RF-induction heated side-pumped synthesis chamber for the production of such. Such a method, while capable of producing large volumes of carbon nanotubes, concurrently permits the use of a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization. The method of the present invention utilizes a free electron laser operating at high average and peak fluence to illuminate a rotating and translating graphite/catalyst target to obtain high yields of SWNTs without the use of a vacuum chamber.

Smith, Michael W. (Newport News, VA); Jordan, Kevin (Newport News, VA); Park, Cheol (Yorktown, VA)

2010-03-02

237

Gigahertz frequency flexible carbon nanotube transistors  

NASA Astrophysics Data System (ADS)

We investigate the high frequency performances of flexible field-effect transistors based on carbon nanotubes. A large density of mostly aligned carbon nanotubes deposited on a flexible substrate by dielectrophoresis serves as the channel. The transistors display a constant transconductance up to at least 6GHz and a current gain cutoff frequency (fT) as high as 1GHz at VDS=-700mV. Bending tests show that the devices can withstand a high degree of flexion characterized by a constant transconductance for radius of curvature as small as 3.3mm.

Chimot, N.; Derycke, V.; Goffman, M. F.; Bourgoin, J. P.; Happy, H.; Dambrine, G.

2007-10-01

238

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

239

Rapid and effective sample clean-up based on magnetic multiwalled carbon nanotubes for the determination of pesticide residues in tea by gas chromatography-mass spectrometry.  

PubMed

In this work, amine-functionalised magnetic nanoparticles and multiwalled carbon nanotubes (MNPs/MWCNTs) composites were synthesised by a simple method and applied as an adsorbent for rapid clean-up of acetonitrile extracts of tea samples prior to analysing eight pesticide residues by gas chromatography-mass spectrometry. Several parameters affecting the sampling and treatment efficiency were investigated, including extraction solvent, sonication time, weight ratio of MWCNTs to MNPs in the composites, amount of adsorbent, clean-up time and washing solution. Under the optimised conditions, the recoveries obtained for each pesticide ranged from 72.5% to 109.1% with relative standard deviations lower than 12.6%. Limit of quantification ranged from 0.02 to 0.08 mg kg?¹. The established method was successfully applied to the analysis of pesticide residues in real tea samples. The results indicated that the use of MNPs/MWCNTs composites allowed the simple and expeditious clean-up of complex tea samples for subsequent determination of pesticide residues. PMID:24128556

Deng, Xiaojuan; Guo, Qianjin; Chen, Xiaoping; Xue, Tao; Wang, Hui; Yao, Pei

2014-02-15

240

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

241

Carbon Nanotube Based Deuterium Ion Source for Improved Neutron Generators  

SciTech Connect

Field ionization uses high electric fields to cause the ionization and emission of ions from the surface of a sharp electrode. We are developing a novel field ionization neutron generator using carbon nanotubes (CNT) to produce the deuterium ion current. The generator consists of three major components: a deuterium ion source made of carbon nanotubes, a smooth negatively-biased target electrode, and a secondary electron suppression system. When a negative high voltage is applied on the target electrode, a high gradient electric field is formed at the tips of the carbon nanotubes. This field is sufficiently strong to create deuterium (D) ions at or near the nanotubes which are accelerated to the target causing D-D reactions to occur and the production of neutrons. A cross magnetic field is used to suppress secondary emission electrons generated on the target surface. We have demonstrated field ionization currents of 70 nA (1 {mu}A/cm{sup 2}) at hydrogen gas pressure of 10 mTorr. We have found that the current scales proportionally with CNT area and also with the gas pressure in the range of 1 mTorr to 10 mTorr. We have demonstrated pulse cut-off times as short as 2 {mu}sec. Finally, we have shown the feasibility of generating neutrons using deuterium gas.

Fink, R. L.; Jiang, N.; Thuesen, L. [Applied Nanotech, Inc., 3006 Longhorn Blvd., Ste 107, Austin, TX 78758 (United States); Leung, K. N. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antolak, A. J. [Sandia National Laboratories, Livermore, CA 94550 (United States)

2009-03-10

242

Compressed carbon nanotubes: A family of new multifunctional carbon allotropes  

PubMed Central

The exploration of novel functional carbon polymorphs is an enduring topic of scientific investigations. In this paper, we present simulations demonstrating metastable carbon phases as the result of pressure induced carbon nanotube polymerization. The configuration, bonding, electronic, and mechanical characteristics of carbon polymers strongly depend on the imposed hydrostatic/non-hydrostatic pressure, as well as on the geometry of the raw carbon nanotubes including diameter, chirality, stacking manner, and wall number. Especially, transition processes under hydrostatic/non-hydrostatic pressure are investigated, revealing unexpectedly low transition barriers and demonstrating sp2?sp3 bonding changes as well as peculiar oscillations of electronic property (e.g., semiconducting?metallic?semiconducting transitions). These polymerized nanotubes show versatile and superior physical properties, such as superhardness, high tensile strength and ductility, and tunable electronic properties (semiconducting or metallic). PMID:23435585

Hu, Meng; Zhao, Zhisheng; Tian, Fei; Oganov, Artem R.; Wang, Qianqian; Xiong, Mei; Fan, Changzeng; Wen, Bin; He, Julong; Yu, Dongli; Wang, Hui-Tian; Xu, Bo; Tian, Yongjun

2013-01-01

243

Compressed carbon nanotubes: a family of new multifunctional carbon allotropes.  

PubMed

The exploration of novel functional carbon polymorphs is an enduring topic of scientific investigations. In this paper, we present simulations demonstrating metastable carbon phases as the result of pressure induced carbon nanotube polymerization. The configuration, bonding, electronic, and mechanical characteristics of carbon polymers strongly depend on the imposed hydrostatic/non-hydrostatic pressure, as well as on the geometry of the raw carbon nanotubes including diameter, chirality, stacking manner, and wall number. Especially, transition processes under hydrostatic/non-hydrostatic pressure are investigated, revealing unexpectedly low transition barriers and demonstrating sp(2)?sp(3) bonding changes as well as peculiar oscillations of electronic property (e.g., semiconducting?metallic?semiconducting transitions). These polymerized nanotubes show versatile and superior physical properties, such as superhardness, high tensile strength and ductility, and tunable electronic properties (semiconducting or metallic). PMID:23435585

Hu, Meng; Zhao, Zhisheng; Tian, Fei; Oganov, Artem R; Wang, Qianqian; Xiong, Mei; Fan, Changzeng; Wen, Bin; He, Julong; Yu, Dongli; Wang, Hui-Tian; Xu, Bo; Tian, Yongjun

2013-01-01

244

Improved Method of Purifying Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

An improved method of removing the residues of fabrication from carbon nanotubes has been invented. These residues comprise amorphous carbon and metal particles that are produced during the growth process. Prior methods of removing the residues include a variety of processes that involved the use of halogens, oxygen, or air in both thermal and plasma processes. Each of the prior methods entails one or more disadvantages, including non-selectivity (removal or damage of nanotubes in addition to removal of the residues), the need to dispose of toxic wastes, and/or processing times as long as 24 hours or more. In contrast, the process described here does not include the use of toxic chemicals, the generation of toxic wastes, causes little or no damage to the carbon nanotubes, and involves processing times of less than 1 hour. In the improved method, purification is accomplished by flowing water vapor through the reaction chamber at elevated temperatures and ambient pressures. The impurities are converted to gaseous waste products by the selective hydrogenation and hydroxylation by the water in a reaction chamber. This process could be performed either immediately after growth or in a post-growth purification process. The water used needs to be substantially free of oxygen and can be obtained by a repeated freeze-pump-thaw process. The presence of oxygen will non-selectively attach the carbon nanotubes in addition to the amorphous carbon.

Delzeit, Lance D.

2004-01-01

245

Surface coating of carbon nanofibers/nanotubes by electrodeposition for multifunctionalization  

NASA Astrophysics Data System (ADS)

Carbon nanomaterials in the form of paper sheets have been used as platforms to achieve multifunctionality. Combined with electrochemical deposition, room temperature synthesis of magnetic Ni coatings on individual carbon nanofibers (CNF) and/or carbon nanotubes (CNT) has been realized through solution penetration and ion diffusion. In addition to significant electrical conductivity improvement, the magnetic responses of the Ni coated carbon nanopaper sheets can be tuned within large ranges in terms of saturation magnetic field, remnant magnetization and coercivity. After being re-suspended in liquids, the magnetized CNFs/CNTs can be aligned with small external magnetic fields.

Xing, H.; Sun, L.; Song, G.; Gou, J.; Hao, Y. W.

2008-01-01

246

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

247

Antibody functionalization of carbon nanotubes for breast cancer applications  

Microsoft Academic Search

Carbon nanotubes (CNTs) are remarkable solid state nanomaterials with unique electrical and mechanical properties. The electronic properties of nanotubes combined with biological molecules, such as proteins, could make miniature devices for biological sensing applications. The interaction of single wall carbon nanotubes (SWNTs) with antibodies is presented. This approach is used towards developing a biosensor for breast cancer detection, by functionalizing

Kasif Teker; Ranjani Sirdeshmukh; Balaji Panchapakesan

2004-01-01

248

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...

249

Local Electronic Structure of Single-Walled Carbon Nanotubes from  

E-print Network

Local Electronic Structure of Single-Walled Carbon Nanotubes from Electrostatic Force Microscopy An atomic force microscope was used to locally perturb and detect the charge density in carbon nanotubes. Changing the tip voltage varied the Fermi level in the nanotube. The local charge density increased

Bockrath, Marc

250

Defective fullerenes and nanotubes as molecular magnets: An ab initio study Yong-Hyun Kim,* Jin Choi, and K. J. Chang  

E-print Network

Defective fullerenes and nanotubes as molecular magnets: An ab initio study Yong-Hyun Kim,* Jin the electronic and magnetic structures of a C60 fullerene during a structural transition to a nanotube segment all- carbon nanostructures, related to fullerenes and nanotubes with a particular arrangement

251

Conductance of AFM Deformed Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

This viewgraph presentation provides information on the electrical conductivity of carbon nanotubes upon deformation by atomic force microscopy (AFM). The density of states and conductance were computed using four orbital tight-binding method with various parameterizations. Different chiralities develop bandgap that varies with chirality.

Svizhenko, Alexei; Maiti, Amitesh; Anatram, M. P.; Biegel, Bryan (Technical Monitor)

2002-01-01

252

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

253

Neon adsorbed in carbon nanotube bundles  

Microsoft Academic Search

By means of path integral Monte Carlo calculations we were able to estimate the chemical potential of Ne atoms adsorbed in the interstitial channels of a bundle of (10,10) carbon nanotubes. This allows us to estimate the temperature and pressure conditions for Ne adsorption in those channels. We also calculate the conditions for Ne filling of a bundle of (5,5)

M. C. Gordillo; L. Brualla; S. Fantoni

2004-01-01

254

Chemistry of Carbon Nanotubes for Everyone  

ERIC Educational Resources Information Center

Carbon nanotubes (CNTs) have the extraordinary potential to change our lives by improving existing products and enabling new ones. Current and future research and industrial workforce professionals are very likely to encounter some aspects of nanotechnology including CNT science and technology in their education or profession. The simple structure…

Basu-Dutt, Sharmistha; Minus, Marilyn L.; Jain, Rahul; Nepal, Dhriti; Kumar, Satish

2012-01-01

255

Carbon Nanotube MicroElectrode Array  

Microsoft Academic Search

A novel class of micro electrodes, specifically designed to interface with neuronal systems, is presented. The electrodes were fabricated by synthesizing high density carbon nanotube islands on lithographically defined, passivated titanium nitride conductors on a silicon dioxide substrate. Here we show that these novel bio-compatible electrodes facilitate two special functions: neuronal tissue patterning as well as recording of the cell's

T. Gabay; M. Ben-David; I. Kalifa; Z. R. Abrams; R. Sorkin; E. Ben-Jacob; Y. Hanein

2007-01-01

256

Improvement of Carbon Nanotubes using Cryogenic Treatment  

Microsoft Academic Search

Functional improvement of single-walled carbon nanotubes coated on polyimide Kapton HN was studied by means of cyclic cryogenic treatment. Immersing in liquid nitrogen at 77 K joining in heat annealing at 500 K induced the increase of D-G ratio and electrical conductivity in conjecture to the partial remedial junction with the coexisted stiction on surface. The coated thickness was deliberately

Dae-Weon Kim; Eui-Yun Jang; Seung-Min Lee; Wal-jun Kim; Jong-Hoon Lee; Jacob Kleiman

2007-01-01

257

Electron phonon interaction in carbon nanotube devices  

Microsoft Academic Search

With the end of silicon technology scaling in sight, there has been a lot of interest in alternate novel channel materials and device geometry. Carbon nanotubes, the ultimate one-dimensional (1D) wire, is one such possibility. Since the report of the first CNT transistors, lots has been learned about CNT device physics, their scaling properties, and their advantage and disadvantages as

Sayed Hasan

2006-01-01

258

Diffusion through Carbon Nanotube Semipermeable membranes  

Microsoft Academic Search

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,

Bakajin

2006-01-01

259

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

260

Torsional electromechanical quantum oscillations in carbon nanotubes  

E-print Network

Torsional electromechanical quantum oscillations in carbon nanotubes TZAHI COHEN-KARNI1 *, LIOR and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel 2 Chemical Research Support, Weizmann by mechanical torsion4 can induce conductance oscillations, which can be attributed to metal

Joselevich, Ernesto

261

Physics and applications of aligned carbon nanotubes  

Microsoft Academic Search

Ever since the discovery of carbon nanotubes (CNTs) by Iijima in 1991, there have been extensive research efforts on their synthesis, physics, electronics, chemistry, and applications due to the fact that CNTs were predicted to have extraordinary physical, mechanical, chemical, optical, and electronic properties. Among the various forms of CNTs, single-walled and multi-walled, random and aligned, semiconducting and metallic, aligned

Yucheng Lan; Yang Wang; Z. F. Ren

2011-01-01

262

Amphiphobic Carbon Nanotubes as Macroemulsion Surfactants  

E-print Network

their extreme mechanical strength8 and thermal management power9 to develop CNT-based composites.10,11 This new evidence for single-walled carbon nanotubes (SWNTs) acting as a natural "surfactant" or interphase material tubes tend to form bundles due to longitudinal van der Waals forces, and * To whom correspondence should

Wang, Howard "Hao"

263

Growth of decorated carbon nano-tubes  

Microsoft Academic Search

Decomposition of methane in a nitrogen atmosphere using bias-enhanced hot filament chemical vapour deposition results in the growth of nitrogenated carbon tubes. Different shapes were formed ranging from spherical aggregates to twisted nano-tubes. All these structures were grown direct onto pure Si wafer. Glow discharge optical emission spectroscopy reveals the presence of tungsten carbide impurities at the interface. Graphitic sheets

Ralph Kurt; Ayatollah Karimi; Volker Hoffmann

2001-01-01

264

Three dimensional carbon-nanotube polymers.  

PubMed

Eight fascinating sp(2)- and sp(3)-hybridized carbon allotropes have been uncovered using a newly developed ab initio particle-swarm optimization methodology for crystal structure prediction. These crystalline allotropes can be viewed respectively as three-dimensional (3D) polymers of (4,0), (5,0), (7,0), (8,0), (9,0), (3,3), (4,4), and (6,6) carbon nanotubes, termed 3D-(n, 0) or 3D-(n, n) carbons. The ground-state energy calculations show that the carbons all have lower energies than C(60) fullerene, and some are energetically more stable than the van der Waals packing configurations of their nanotube parents. Owing to their unique configurations, they have distinctive electronic properties, high Young's moduli, high tensile strength, ultrahigh hardness, good ductility, and low density, and may be potentially applied to a variety of needs. PMID:21838290

Zhao, Zhisheng; Xu, Bo; Wang, Li-Min; Zhou, Xiang-Feng; He, Julong; Liu, Zhongyuan; Wang, Hui-Tian; Tian, Yongjun

2011-09-27

265

Flame synthesis of carbon nanotubes and metallic nanomaterials  

E-print Network

Carbon nanotubes are a remarkable material with many appealing properties. Despite the appeal of this material, there are few synthesis techniques capable of producing nanotubes in large quantities at low-cost. The broad ...

Height, Murray John, 1975-

2003-01-01

266

Characterizing carbon-nanotube devices for an integrated sensor system  

E-print Network

While carbon nanotubes (CNT) offer promise for future nano-electronic applications, reliably controlling CNT growth has been a big challenge. As-grown devices can have a number of different nanotubes, which can be either ...

Lee, Kyeong-Jae

2007-01-01

267

Functionalized Few-Walled Carbon Nanotubes for Mechanical  

E-print Network

provide a di- rection toward solving all these problems. FWNTs, defined as nanotubes with side- walls of 2 American Chemical Society ABSTRACT Compared to single-walled carbon nanotubes (SWNTs) and more defective

Liu, Jie

268

Autonomous propulsion of carbon nanotubes powered by a multienzyme ensemble.  

PubMed

Covalent attachment of the enzymes glucose oxidase and catalase to carbon nanotubes enables the tandem catalytic conversion of glucose and H(2)O(2) formed to power autonomous movement of the nanotubes. PMID:18354790

Pantarotto, Davide; Browne, Wesley R; Feringa, Ben L

2008-04-01

269

Multifunctional and recollectable carbon nanotube ponytails for water purification.  

PubMed

Carbon nanotubes (CNTs) are promising nanomaterials that have the potential to revolutionize water treatment practices in the future. The direct use of unbounded CNTs, however, poses health risks to humans and ecosystems because they are difficult to separate from treated water. Here, we report the design and synthesis of carbon nanotube ponytails (CNPs) by integrating CNTs into micrometer-sized colloidal particles, which greatly improves the effectiveness of post-treatment separation using gravitational sedimentation, magnetic attraction, and membrane filtration. We further demonstrate that CNPs can effectively perform major treatment tasks including adsorption, disinfection, and catalysis. Using model pollutants such as methylene blue, Escherichia coli, and p-nitrophenol, we show that all the surfaces of individual CNTs in CNPs are accessible during water treatment. Our results suggest that the rational design of hierarchical structures represents a feasible approach to develop nanomaterials for engineering applications such as water and wastewater treatment. PMID:24806877

Wang, Haitao; Ma, Hanyu; Zheng, Wen; An, Dingding; Na, Chongzheng

2014-06-25

270

Reversible fluorescence quenching in carbon nanotubes for biomolecular sensing  

Microsoft Academic Search

Biosensing applications of single-walled carbon nanotubes have been demonstrated in solid-state device structures. Bioanalyte sensing schemes based on coupling of reversible nanotube fluorescence quenching to redox reactions paired to enzymatic peroxide generation have also been pursued. Here we show a new approach to highly sensitive nanotube-based optical sensing. Single-walled carbon nanotubes interacting with dye-ligand conjugates-a redox-active dye molecule that is

B. C. Satishkumar; Leif O. Brown; Yuan Gao; Chun-Chih Wang; Hsing-Lin Wang; Stephen K. Doorn

2007-01-01

271

Functionalized Carbon Nanotubes for Mixed Matrix Membrane  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) have generated great interest within the many areas of nanotechnology due to their superior and outstanding physical properties. However effective dispersion in many solvents has imposed limitations upon the use of CNTs in a number of novel applications. Functionalization presents a solution for CNTs to be more soluble which make them integrate well into any organic, inorganic or biological systems. CNTs can be easily functionalized using cyclodextrin (CD) treatment. The CD modification of carbon nanotubes is both simple and effective. It requires no prolonged heating, filtration and washing which can severely damage the small diameter nanotubes. The formation of surface functional groups and changes of nanotubes structures of functionalized carbon nanotubes (f-CNTs) were monitored by Fourier transform infrared spectroscopy (FTIR), Thermo gravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM), respectively. From the TGA results, the amount of weight loss of the f-CNTs in varying ratios indicated the amount of CD that was functionalized. It was also noted that the FTIR spectra showed the presence of functional groups associated with CD in the f-CNTs. As a result, the cyclodextrin groups were found to be possibly adsorbed at the surface of the nanotubes walls. The f-CNTs showed substantial solubility in N-methyl-2-pyrrolidone (NMP) which helps in a better distribution of the CNTs in the mixed matrix membrane (MMM) prepared. Hence, the influence of the f-CNTs in the polymer matrix will give rise to enhanced physical properties of the MMM suitable for applications in gas separations.

Sanip, Suhaila Mohd.; Ismail, Ahmad Fauzi; Aziz, Madzlan; Soga, Tetsuo

272

Tunable Kondo physics in a carbon nanotube double quantum dot.  

PubMed

We investigate a tunable two-impurity Kondo system in a strongly correlated carbon nanotube double quantum dot, accessing the full range of charge regimes. In the regime where both dots contain an unpaired electron, the system approaches the two-impurity Kondo model. At zero magnetic field the interdot coupling disrupts the Kondo physics and a local singlet state arises, but we are able to tune the crossover to a Kondo screened phase by application of a magnetic field. All results show good agreement with a numerical renormalization group study of the device. PMID:23102352

Chorley, S J; Galpin, M R; Jayatilaka, F W; Smith, C G; Logan, D E; Buitelaar, M R

2012-10-12

273

Biomolecules Functionalized Carbon Nanotubes and Their Applications  

NASA Astrophysics Data System (ADS)

In recent years, functionalization of carbon nanotubes (CNTs) with biomolecules such as nucleotide acids, proteins, and artificial polymers have emerged as a new exciting field. Theoretical and experimental studies of structure and function of bio-inspired CNT composites have made great advances. The importance of nucleic acids, proteins, and synthesized polymers to the fundamental developments in CNT-based bio-nano-composites or devices has been recognized. In particular, biomechanics, biochemistry, thermodynamics, electronic, optical and magnetic properties, and biocompatibility and toxicology of the bio-inspired CNT composites have become a new interdisciplinary frontier in life science and nanomaterial science. Bio-inspired CNT composites have been actively exploited potentials in applications such as gene/drug delivery system, tissue engineering scaffolds, hydrogen storage, molecular imaging, biocatalyst systems, biosensors, and antifouling films. Here we review the main advances in this field over the past few years, explore their application prospects, and discuss the issues, approaches, and challenges, with the aim of improving and developing CNT-based bio-nanotechnology.

Cui, Daxiang

274

Raman Scattering in Carbon Nanotubes  

E-print Network

interpret the physical origin of each spectral feature. In the bulk measurements two new ef- fects as a characterization tool for the diameter distribution and purity of nanotube samples. Also samples of individual and chemistry it has required interaction with both chemist and physi- cists which sometimes has led

Nygård, Jesper

275

Terahertz Response of Carbon Nanotube Transistors  

NASA Astrophysics Data System (ADS)

We present an approach for time-dependent quantum transport based on a self-consistent nonequilibrium Green function formalism. The technique is applied to a ballistic carbon nanotube transistor in the presence of a time-harmonic signal at the gate. In the on state, the dynamic conductance exhibits plasmonic resonant peaks at terahertz frequencies. These vanish in the off state, and the dynamic conductance displays smooth oscillations, a signature of single-particle quantum effects. We show that the nanotube kinetic inductance plays an essential role in the high-frequency behavior.

Kienle, Diego; Léonard, François

2009-07-01

276

Terahertz response of carbon nanotube transistors.  

PubMed

We present an approach for time-dependent quantum transport based on a self-consistent nonequilibrium Green function formalism. The technique is applied to a ballistic carbon nanotube transistor in the presence of a time-harmonic signal at the gate. In the on state, the dynamic conductance exhibits plasmonic resonant peaks at terahertz frequencies. These vanish in the off state, and the dynamic conductance displays smooth oscillations, a signature of single-particle quantum effects. We show that the nanotube kinetic inductance plays an essential role in the high-frequency behavior. PMID:19659227

Kienle, Diego; Léonard, François

2009-07-10

277

High temperature rearrangement of disordered nanoporous carbon at the interface with single wall carbon nanotubes  

Microsoft Academic Search

Composites of nanoporous carbon and single wall carbon nanotubes were heat treated in vacuum at temperatures ranging from 1200 to 2000°C. The resultant interface between the two allotropes of carbon was characterized using high resolution transmission electron microscopy and Raman spectroscopy. At the interface between the nanoporous carbon and the nanotube, the nanotube served as a template for ordering and

Bo Yi; Ramakrishnan Rajagopalan; Christopher L. Burket; Henry C. Foley; Xiaoming Liu; Peter C. Eklund

2009-01-01

278

Functionalization of vertically aligned carbon nanotubes  

PubMed Central

Summary This review focuses and summarizes recent studies on the functionalization of carbon nanotubes oriented perpendicularly to their substrate, so-called vertically aligned carbon nanotubes (VA-CNTs). The intrinsic properties of individual nanotubes make the VA-CNTs ideal candidates for integration in a wide range of devices, and many potential applications have been envisaged. These applications can benefit from the unidirectional alignment of the nanotubes, the large surface area, the high carbon purity, the outstanding electrical conductivity, and the uniformly long length. However, practical uses of VA-CNTs are limited by their surface characteristics, which must be often modified in order to meet the specificity of each particular application. The proposed approaches are based on the chemical modifications of the surface by functionalization (grafting of functional chemical groups, decoration with metal particles or wrapping of polymers) to bring new properties or to improve the interactions between the VA-CNTs and their environment while maintaining the alignment of CNTs. PMID:23504581

Snyders, Rony; Colomer, Jean-Francois

2013-01-01

279

Influence of carbon nanotubes addition on carbon–carbon supercapacitor performances in organic electrolyte  

Microsoft Academic Search

This paper presents the performances of 4cm2 supercapacitors cells assembled with 200?m thick active material films composed with activated carbon and carbon nanotubes mixture in organic electrolyte. Galvanostatic and electrochemical spectroscopy impedance measurements have been carried out. Galvanostatic measurements show that both internal resistance and specific capacitance decrease when the carbon nanotubes content increases in the active material. With 15%

C. Portet; P. L. Taberna; P. Simon; E. Flahaut

2005-01-01

280

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

281

Spin-based optomechanics with carbon nanotubes.  

PubMed

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

282

Multifunctional carbon nanofiber/nanotube smart materials  

NASA Astrophysics Data System (ADS)

This paper discusses the development of new multifunctional smart materials based on Carbon Nanofibers (CNF) and Multi-Wall Carbon Nanotubes (MWCNT). The material properties of CNF/MWCNT are a little lower than the properties of Single Wall Carbon Nanotubes (SWCNT). However, the CNF/MWCNT have the potential for more practical applications since their cost is lower. This paper discusses the development of four CNF/MWCNT-based sensors and actuators. These are: (i) an Electrochemical Wet Actuator for use in a liquid electrolyte, (ii) an Electrochemical Dry Actuator for use in a dry environment, (iii) a Bioelectronic sensor; and (iv) a MWCNT neuron for structural health monitoring. These materials are exciting because of their unique properties and many applications.

Yun, Yeo-Heung; Kang, Inpil; Gollapudi, Ramanand; Lee, Jong W.; Hurd, Douglas; Shanov, Vesselin N.; Schulz, Mark J.; Kim, Jay; Shi, Donglu; Boerio, J. F.; Subramaniam, Srinivas

2005-05-01

283

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

284

Physicochemical properties of carbon nanotubes obtained from peat moss  

NASA Astrophysics Data System (ADS)

It has been established that mechanochemical treatment of amorphous carbon synthesized by pyrolysis from brown peat moss leads to the formation of carbon nanotubes. Complex studies of the sorptive properties of pyrolytic amorphous carbon and multiwalled nanotubes obtained from peat moss have been made. It has been shown that the ability of carbon nanotubes for acidic modification depends on the technological parameters of their formation, and the efficiency of the sorptive capacity volume of such nanotubes depends on their storage time. The possibility of using carbon materials from peat moss as effective enterosorbents has been considered.

Onishchenko, D. V.; Reva, V. P.

2013-03-01

285

Osmotic water transport through carbon nanotube membranes  

PubMed Central

We use molecular dynamics simulations to study osmotically driven transport of water molecules through hexagonally packed carbon nanotube membranes. Our simulation setup comprises two such semipermeable membranes separating compartments of pure water and salt solution. The osmotic force drives water flow from the pure-water to the salt-solution compartment. Monitoring the flow at molecular resolution reveals several distinct features of nanoscale flows. In particular, thermal fluctuations become significant at the nanoscopic length scales, and as a result, the flow is stochastic in nature. Further, the flow appears frictionless and is limited primarily by the barriers at the entry and exit of the nanotube pore. The observed flow rates are high (5.8 water molecules per nanosecond and nanotube), comparable to those through the transmembrane protein aquaporin-1, and are practically independent of the length of the nanotube, in contrast to predictions of macroscopic hydrodynamics. All of these distinct characteristics of nanoscopic water flow can be modeled quantitatively by a 1D continuous-time random walk. At long times, the pure-water compartment is drained, and the net flow of water is interrupted by the formation of structured solvation layers of water sandwiched between two nanotube membranes. Structural and thermodynamic aspects of confined water monolayers are studied. PMID:12878724

Kalra, Amrit; Garde, Shekhar; Hummer, Gerhard

2003-01-01

286

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

287

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

288

On the role of interband surface plasmons in carbon nanotubes  

NASA Astrophysics Data System (ADS)

We review the properties of collective surface excitations—excitons and interband plasmons—in single-walled and double-walled carbon nanotubes. We show that an electrostatic field applied perpendicular to the nanotube axis can control the exciton-plasmon coupling in individual small-diameter (?nm) singlewalled nanotubes, both in the linear excitation regime and in the non-linear excitation regime with the photoinduced biexcitonic states formation. For double-walled carbon nanotubes, we report a profound effect of interband surface plasmons on the inter-tube Casimir force at tube separations similar to their equilibrium distances. Strong overlapping plasmon resonances from both tubes warrant their stronger attraction. Nanotube chiralities possessing such collective excitation features will result in forming the most favorable innerouter tube combination in double-walled carbon nanotubes. These findings pave the way for the development of new generation of tunable optoelectronic and nano-electromechanical device applications with carbon nanotubes.

Bondarev, I. V.; Woods, L. M.; Popescu, A.

2011-11-01

289

Synthesis of Hollow Carbon Nanofibers and Filled Carbon Nanotubes using Chemical Vapor Deposition Technique.  

NASA Astrophysics Data System (ADS)

Hollow carbon nanofibers (CNFs) and filled carbon nanotubes were created using chemical vapor deposition (CVD). Hollow carbon nanofibers were synthesized in porous anodic aluminum oxide templates (AAO) by CVD of methane (CH4) with ferrocene (C10H10Fe), indium tin oxide (ITO) and iron nitride (Fe(NO3)3) as catalyst at 910 C. Carbon nanotubes were filled with iron using CVD of methane. The source of iron in this process was ferrocene. Both the nanostructures were viewed under SEM and TEM. The CNFs grown within the pores of the aluminum oxide membranes are uniform with lengths of about 50 mm and outer diameters of about 200 nm. A diameter of 20-30 nm was measured for the iron filled sample. The magnetic transport properties of the samples will be presented.

Shay, Kevin; Moiseeva, Evgeniya; Sumanasekera, Gamini

2006-03-01

290

Remote Joule heating by a carbon nanotube  

NASA Astrophysics Data System (ADS)

Minimizing Joule heating remains an important goal in the design of electronic devices. The prevailing model of Joule heating relies on a simple semiclassical picture in which electrons collide with the atoms of a conductor, generating heat locally and only in regions of non-zero current density, and this model has been supported by most experiments. Recently, however, it has been predicted that electric currents in graphene and carbon nanotubes can couple to the vibrational modes of a neighbouring material, heating it remotely. Here, we use in situ electron thermal microscopy to detect the remote Joule heating of a silicon nitride substrate by a single multiwalled carbon nanotube. At least 84% of the electrical power supplied to the nanotube is dissipated directly into the substrate, rather than in the nanotube itself. Although it has different physical origins, this phenomenon is reminiscent of induction heating or microwave dielectric heating. Such an ability to dissipate waste energy remotely could lead to improved thermal management in electronic devices.

Baloch, Kamal H.; Voskanian, Norvik; Bronsgeest, Merijntje; Cumings, John

2012-05-01

291

Double Layer Charging for Conductivity Enhancement of Pure Metallic and Semiconducting Single Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Injecting high electronic charge densities can profoundly change the optical, electrical, and magnetic properties of materials. Evidence suggests a possibility of significantly improving conductivity of carbon nanotubes through double layer charge injection. Double layer charge injection can prove to be a powerful method when applied to carbon nanotubes because of theirs high surface area and chemical stability. Investigation has commenced on the effect of charging on various types of carbon nanotubes, specifically 99% purified single wall semiconducting and single wall metallic tubes. An electrical double layer is electrochemically introduced upon a sheet of carbon nanotubes via application of potential (up to ±5 volts) to a sample immersed in ionic-liquid-based electrolyte. Resistance of carbon nanotube as a function of applied charging voltage is recorded to determine the effects of charge injection. Results show that the electrical double layer considerably reduces the resistance across both samples. ESR/LFMA studies combined with low temperature magnetic and transport measurements are conducted to search for charge injection induced superconductivity in carbon nanotubes.

Mayo, Nathanael; Kuznetsov, Alexander; Zakhidov, Anvar

2011-03-01

292

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

293

Carbon nanotube labeled immunosensor for lateral flow diagnostics  

Microsoft Academic Search

This paper presents the development and demonstration of a new immunosensor utilizing multi-walled carbon nanotubes (MWCNTs) labeled antibodies on lateral flow system. The developed immunosensor utilizes the unique properties of carbon nanotubes coupled with highly specific biorecognition capabilities of antibodies for sensitive, low-concentration, and rapid detection mechanism. Carbon nano-tubes are excellent electrical conductors, and have chemical stability, color generation, and

Adeyabeba Abera; Jin-Woo Choi

2009-01-01

294

Thermogravimetric Analysis of Single-Wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

An improved protocol for thermogravimetric analysis (TGA) of samples of single-wall carbon nanotube (SWCNT) material has been developed to increase the degree of consistency among results so that meaningful comparisons can be made among different samples. This improved TGA protocol is suitable for incorporation into the protocol for characterization of carbon nanotube material. In most cases, TGA of carbon nanotube materials is performed in gas mixtures that contain oxygen at various concentrations. The improved protocol is summarized.

Arepalli, Sivram; Nikolaev, Pavel; Gorelik, Olga

2010-01-01

295

Noise conductance of carbon nanotube transistors J. Chaste,1, 2  

E-print Network

Noise conductance of carbon nanotube transistors J. Chaste,1, 2 E. Pallecchi,1, 2 P. Morfin,1, 2 G nanotube transistors. Gate capacitance Cg, drain conductance gd, transconductance gm and current-noise data are analyzed with a ballistic 1-dimensional nano-transistor model where the nanotube channel is described

Plaçais, Bernard

296

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

297

Energy absorption capacity of carbon nanotubes under ballistic impact  

NASA Astrophysics Data System (ADS)

Carbon nanotubes have great potential applications in making ballistic-resistance materials. This letter analyzes the impact of a bullet on nanotubes of different radii in two extreme cases. For a nanotube with one end fixed, the maximum nanotube enduring bullet speed increases and the energy absorption efficiency decreases with the increase in relative heights at which the bullet strikes; these values are independent of the nanotube radii when the bullet hits at a particular relative height. For a nanotube with both ends fixed, the energy absorption efficiency reaches minimum when the bullet strikes around a relative height of 0.5.

Mylvaganam, Kausala; Zhang, L. C.

2006-09-01

298

Load transfer mechanism in carbon nanotube ropes , Wing Kam Liub  

E-print Network

in a single walled carbon nanotube (SWCNT) bundle consisting of seven (10,10) SWCNTs: one core tube surrounded loading studies of multi-walled carbon nano- 0266-3538/03/$ - see front matter # 2003 Elsevier Ltd. AllLoad transfer mechanism in carbon nanotube ropes Dong Qiana , Wing Kam Liub , Rodney S. Ruoffb

299

Exohydrogenated single-wall carbon nanotubes T. Yildirim,1  

E-print Network

of hydrogen and nano- tube system. Hydrogen-carbon interactions have been studied exten- sively bothExohydrogenated 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

Yildirim, Taner

300

Cement Based Foam Concrete Reinforced by Carbon Nanotubes  

Microsoft Academic Search

The main task of the presented research was to investigate the carbon nanotubes, synthesized from aromatic hydrocarbons and as well as to investigate the possibilities of production and main technological properties of Portland cement based foam concrete reinforced by dispersed carbon nanotubes. The method of stimulation of dehydropolycon- densation and carbonization of aromatic hydrocarbons in chemical active environment (melts of

Grigorij YAKOVLEV; Albinas GAILIUS

2006-01-01

301

Ordered water inside carbon nanotubes: formation of pentagonal to octagonal ice-nanotubes  

Microsoft Academic Search

We report on a systematic X-ray diffraction analysis for the ordered water inside single-walled carbon nanotubes (SWNTs) with diameters of 10.9–15.2 Å. Four distinct ordered structures identified in this diameter range were assigned to polygonal ice-nanotubes predicted by molecular dynamics (MD) calculations. The ordering transition temperature rose from 190 K of octagonal ice-nanotubes to 300 K of pentagonal ice-nanotubes without

Yutaka Maniwa; Hiromichi Kataura; Masatoshi Abe; Akiko Udaka; Shinzo Suzuki; Yohji Achiba; Hiroshi Kira; Kazuyuki Matsuda; Hiroaki Kadowaki; Yutaka Okabe

2005-01-01

302

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

303

Block copolymer-templated iron oxide nanoparticles for bimodal growth of multi-walled carbon nanotubes  

E-print Network

Since their discovery carbon nanotubes (CNTs) have sparked great interest due to their exceptional mechanical, electrical, and thermal properties. These properties make carbon nanotubes desirable for numerous applications ...

Yazzie, Kyle E

2008-01-01

304

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

305

Upper bound to the thermal conductivity of carbon nanotube pellets  

NASA Astrophysics Data System (ADS)

Using atomistic Green's function calculations, we find that the phonon thermal conductivity of pellets composed of ˜?m long carbon nanotubes has an upper bound of a few W/m K. This is in striking contrast with the extremely high thermal conductivity of individual nanotubes (˜3000 W/m K). We show that, at room temperature, this upper bound does not depend on the nanotube diameter. Conversely, for low temperatures, an inverse proportionality with nanotube diameter is predicted. We present concrete results as a function of nanotube length and chirality, pellet density, and temperature. These results imply that carbon nanotube pellets belong to the category of thermal insulators, contrasting with the good conducting properties of parallel nanotube arrays, or individual nanotubes.

Chalopin, Yann; Volz, Sebastian; Mingo, Natalio

2009-04-01

306

Aharonov-Bohm effects on bright and dark excitons in carbon nanotubes  

Microsoft Academic Search

A short-range part of the Coulomb interaction causes splitting and shift of excitons due to exchange interaction and mixing between different valleys in semiconducting carbon nanotubes. In the absence of a magnetic flux only a single exciton is optically active (bright) and all others are inactive (dark). Two bright excitons appear in the presence of an Aharonov- Bohm magnetic flux.

Tsuneya Ando

2006-01-01

307

Carbon nanotube applications for CMOS back-end processing  

E-print Network

Carbon nanotubes are a recently discovered material with excellent mechanical, thermal, and electronic properties. In particular, they are potential ballistic transporters and are theorized to have thermal conductivities ...

Wu, Tan Mau, 1979-

2005-01-01

308

Continuous Growth of Vertically Aligned Carbon Nanotubes Forests  

E-print Network

Vertically aligned carbon nanotubes are one of the most promising materials due their numerous applications in flexible electronic devices, biosensors and multifunctional aircraft materials, among others. However, the ...

Guzman de Villoria, Roberto

309

Towards structural health monitoring in carbon nanotube reinforced composites  

E-print Network

An experimental investigation was conducted to understand the non-destructive evaluation (NDE) capabilities of carbon nanotubes (CNTs) of several network architectures towards structural health monitoring (SHM). As ...

Wang, Wennie

2013-01-01

310

DNA-assisted dispersion and separation of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes are man-made one-dimensional carbon crystals with different diameters and chiralities. Owing to their superb mechanical and electrical properties, many potential applications have been proposed for them. However, polydispersity and poor solubility in both aqueous and non-aqueous solution impose a considerable challenge for their separation and assembly, which is required for many applications. Here we report our finding of DNA-assisted dispersion and separation of carbon nanotubes. Bundled single-walled carbon nanotubes are effectively dispersed in water by their sonication in the presence of single-stranded DNA (ssDNA). Optical absorption and fluorescence spectroscopy and atomic force microscopy measurements provide evidence for individually dispersed carbon nanotubes. Molecular modelling suggests that ssDNA can bind to carbon nanotubes through ?-stacking, resulting in helical wrapping to the surface. The binding free energy of ssDNA to carbon nanotubes rivals that of two nanotubes for each other. We also demonstrate that DNA-coated carbon nanotubes can be separated into fractions with different electronic structures by ion-exchange chromatography. This finding links one of the central molecules in biology to a technologically very important nanomaterial, and opens the door to carbon-nanotube-based applications in biotechnology.

Zheng, Ming; Jagota, Anand; Semke, Ellen D.; Diner, Bruce A.; McLean, Robert S.; Lustig, Steve R.; Richardson, Raymond E.; Tassi, Nancy G.

2003-05-01

311

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

312

Polymers containing fullerene or carbon nanotube structures  

Microsoft Academic Search

This review deals with recent progress in studies of polymeric covalent and noncovalent modifications of fullerenes (mainly C60) and carbon nanotubes (CNTs), and their applications. By using functional polymers to react with fullerenes, or synthesizing polymers in the presence of fullerenes, various kinds of polymeric fullerenes can be prepared: side-chain polymers, main-chain polymers, dendritic fullerenes, star-shaped polymers, fullerene end-capped polymers,

Changchun Wang; Zhi-Xin Guo; Shoukuan Fu; Wei Wu; Daoben Zhu

2004-01-01

313

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

314

Neon adsorbed in carbon nanotube bundles  

NASA Astrophysics Data System (ADS)

By means of path integral Monte Carlo calculations we were able to estimate the chemical potential of Ne atoms adsorbed in the interstitial channels of a bundle of (10,10) carbon nanotubes. This allows us to estimate the temperature and pressure conditions for Ne adsorption in those channels. We also calculate the conditions for Ne filling of a bundle of (5,5) tubes with their caps removed.

Gordillo, M. C.; Brualla, L.; Fantoni, S.

2004-12-01

315

Carbon nanotube-based transducers for immunoassays  

Microsoft Academic Search

The attachment of mouse immunoglobulin G (IgG) and anti-mouse IgG antibodies onto carbon nanotubes (CNTs), using either non-covalent or covalent means was investigated. The resultant CNTs were characterised using a variety of techniques including enzyme-linked and fluorescence-linked immunoassays, UV–visible-NIR and Raman spectroscopy, transmission electron microscopy and cyclic voltammetry. TEM images of the adsorbed antibody on the CNTs show that the

Carol Lynam; Niamh Gilmartin; Andrew I. Minetta; Richard O’Kennedy; Gordon Wallace

2009-01-01

316

Mechanical Energy Storage in Carbon Nanotube Springs  

Microsoft Academic Search

Compression of purified, unoriented, highly crystalline single-wall carbon nanotube material reveals an exceptionally large and reversible volume reduction. Density increases rapidly with increasing pressure, approaching that of graphite, and recovers completely upon pressure release. The reversible work done in compressing to 29thinspthinspkbar is 0.18 eV\\/C atom. We attribute this effect to crushing, or flattening the tube cross section from circular

S. A. Chesnokov; V. A. Nalimova; A. G. Rinzler; R. E. Smalley; J. E. Fischer

1999-01-01

317

HYDROGEN CRYOSORPTION ON MULTI WALLED CARBON NANOTUBES  

Microsoft Academic Search

We present a Temperature Programmed Desorption (TPD) study on H2 adsorption on multiwalled carbon nanotubes (MWNT) at very low pressure (<10-6 Torr) and temperature (12-30 K). Our results show a hydrogen take up limit in the range of 10 -8 mol per gram depending on the adsorption temperature. We compare the MWNT cryosorption capacity with that of commonly used activated

F. Xu; M. Barberio; R. Vasta; P. Barone; A. Oliva; L. Papagno; V. Pirronello

318

Carbon Nanotubes by CVD and Applications  

NASA Technical Reports Server (NTRS)

Carbon nanotube (CNT) exhibits extraordinary mechanical and unique electronic properties and offers significant potential for structural, sensor, and nanoelectronics applications. An overview of CNT, growth methods, properties and applications is provided. Single-wall, and multi-wall CNTs have been grown by chemical vapor deposition. Catalyst development and optimization has been accomplished using combinatorial optimization methods. CNT has also been grown from the tips of silicon cantilevers for use in atomic force microscopy.

Cassell, Alan; Delzeit, Lance; Nguyen, Cattien; Stevens, Ramsey; Han, Jie; Meyyappan, M.; Arnold, James O. (Technical Monitor)

2001-01-01

319

Carbon Nanotube Membranes for Water Purification  

NASA Astrophysics Data System (ADS)

Carbon nanotubes are an excellent platform for the fundamental studies of transport through channels commensurate with molecular size. Water transport through carbon nanotubes is also believed to be similar to transport in biological channels such as aquaporins. I will discuss the transport of gas, water and ions through microfabricated membranes with sub-2 nanometer aligned carbon nanotubes as ideal atomically-smooth pores. The measured gas flow through carbon nanotubes exceeded predictions of the Knudsen diffusion model by more than an order of magnitude. The measured water flow exceeded values calculated from continuum hydrodynamics models by more than three orders of magnitude and is comparable to flow rates extrapolated from molecular dynamics simulations and measured for aquaporins. More recent reverse osmosis experiments reveal ion rejection by our membranes. Based on our experimental findings, the current understanding of the fundamentals of water and gas transport and of ion rejection will be discussed. The potential application space that exploits these unique nanofluidic phenomena will be explored. The extremely high permeabilities of these membranes, combined with their small pore size will enable energy efficient filtration and eventually decrease the cost of water purification.[4pt] In collaboration with Francesco Fornasiero, Biosciences and Biotechnology Division, PLS, LLNL, Livermore, CA 94550; Sangil Kim, NSF Center for Biophotonics Science & Technology, University of California at Davis, Sacramento CA 95817; Jung Bin In, Mechanical Engineering Department, UC Berkeley, Berkeley CA 94720; Hyung Gyu Park, Jason K Holt, and Michael Stadermann, Biosciences and Biotechnology Division, PLS, LLNL; Costas P. Grigoropoulos, Mechanical Engineering Department, UC Berkeley; Aleksandr Noy, Biosciences and Biotechnology Division, PLS, LLNL and School of Natural Sciences, University of California at Merced.

Bakajin, Olgica

2009-03-01

320

Nanolithographic control of carbon nanotube synthesis  

E-print Network

......................................................................................75 Figure B - 11. 785 nm Excitation of NiCl 2 Inkwell Dipped Tips..............................77 Figure B - 12. 785 nm Excitation of NiCl 2 Sample. Meniscus Dipped Tip and Cantilever Arm of the Scanning Probe... A ? Contact area between tip and meniscus AFM ? Atomic Force Microscope/Microscopy C o ? Concentration of ink solution adjacent to the tip CNT ? Carbon Nanotube CVD ? Chemical Vapor Deposition D ? Diffusion constant d...

Huitink, David Ryan

2009-05-15

321

Preparation of Carbon Nanotube-Composite  

E-print Network

SUNDEEP SHARMA PREPARATION OF CARBON NANOTUBE-SILK COMPOSITE Major: Biomedical Engineering April 2011 Submitted to the Office of Undergraduate Research Texas A&M University in partial fulfillment of the requirements... Major: Biomedical Engineering April 2011 Submitted to the Office of Undergraduate Research Texas A&M University in partial fulfillment of the requirements for the designation as UNDERGRADUATE RESEARCH SCHOLAR A Senior Scholars Thesis...

Sharma, Sundeep

2011-08-08

322

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

323

Octagonal Defects at Carbon Nanotube Junctions  

PubMed Central

We investigate knee-shaped junctions of semiconductor zigzag carbon nanotubes. Two dissimilar octagons appear at such junctions; one of them can reconstruct into a pair of pentagons. The junction with two octagons presents two degenerate localized states at Fermi energy (EF). The reconstructed junction has only one state near EF, indicating that these localized states are related to the octagonal defects. The inclusion of Coulomb interaction splits the localized states in the junction with two octagons, yielding an antiferromagnetic system. PMID:24089604

Jaskolski, W.; Pelc, M.; Chico, Leonor; Ayuela, A.

2013-01-01

324

Band Gap Fluorescence from Individual Single-Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes. We obtained individual nanotubes, each encased in a cylindrical micelle, by ultrasonically agitating an aqueous dispersion of raw single-walled carbon nanotubes in sodium dodecyl sulfate and then centrifuging to remove tube bundles, ropes, and residual catalyst. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions with metallic tubes and substantially broadens the absorption spectra. At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap-selective protonation of the side walls of the tube. This protonation is readily reversed by treatment with base or ultraviolet light.

O'Connell, Michael J.; Bachilo, Sergei M.; Huffman, Chad B.; Moore, Valerie C.; Strano, Michael S.; Haroz, Erik H.; Rialon, Kristy L.; Boul, Peter J.; Noon, William H.; Kittrell, Carter; Ma, Jianpeng; Hauge, Robert H.; Weisman, R. Bruce; Smalley, Richard E.

2002-07-01

325

Length-dependent extraction of single-walled carbon nanotubes.  

PubMed

A two-phase liquid-liquid extraction process is presented which is capable of extracting water-soluble single-walled carbon nanotubes into an organic phase. The extraction utilizes electrostatic interactions between a common phase transfer agent and the sidewall functional groups on the nanotubes. Large length-dependent van der Waals forces for nanotubes allow the ability to control the length of nanotubes extracted into the organic phase as demonstrated by atomic force microscopy. PMID:16351177

Ziegler, Kirk J; Schmidt, Daniel J; Rauwald, Urs; Shah, Kunal N; Flor, Erica L; Hauge, Robert H; Smalley, Richard E

2005-12-01

326

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

327

Ferroelectric-carbon nanotube memory devices  

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

328

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

329

Imaging carbon nanotubes by scanning electron microscopy  

NASA Astrophysics Data System (ADS)

Scanning electron microscopy (SEM) is used as a primary tool for imaging of nanostructures, including carbon nanotubes. Recent developments of the SEM technique have opened new capabilities for sample analysis at the nanoscale with potential industrial and metrological applications. We will discuss selective imaging of single-walled carbon nanotubes on insulators. The role of the electron beam parameters, effect of surrounding media and substrate, and carbon nanotubes properties on their appearance as seen by an SEM are analysed. The comparison of scanning electron microscopy with atomic force microscopy images will also be presented. Our results support some of the commonly accepted opinions about why such images appear as they do, but mostly contradict them. At the same time our discovery opens new analytical possibilities for applications of an SEM. Funding for this work has been provided by a NASA/MSFC Phase II SBIR, Contract No. NAS8-02102, through a subcontract from Lytec, LLC., and by the NSF NIRT Program, Grant No. 0304506. SEM was done at the Electron Probe Instrumentation Centre at Northwestern University.

Dikin, Dmitriy

2005-03-01

330

Optical modulation of single walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Recent advances in the spectroscopy of single walled carbon nanotubes have significantly enhanced our ability to understand and control their surface chemistry, both covalently and non-covalently. Our work has focused on modulating the optical properties of semiconducting single walled carbon nanotubes as near infrared photoluminescent sensors for chemical analysis. Molecular detection using near-infrared light between 0.9 and 1.3 eV has important biomedical applications because of greater tissue penetration and reduced auto-fluorescent background in thick tissue or whole-blood media. In one system, the transition of DNA secondary structure modulates the dielectric environment of the single-walled carbon nanotube (SWNT) around which it is adsorbed. The SWNT band-gap fluorescence undergoes a red shift when an encapsulating 30-nucleotide oligomer is exposed to counter ions that screen the charged backbone. We demonstrate the detection of the mercuric ions in whole blood, tissue, and from within living mammalian cells using this technology. Similar results are obtained for DNA hybridization and the detection of single nucleotide polymorphism. We also report the synthesis and successful testing of near-infrared ?-D-glucose sensors2 that utilize a different mechanism: a photoluminescence modulation via charge transfer. The results demonstrate new opportunities for nanoparticle optical sensors that operate in strongly absorbing media of relevance to medicine or biology.

Strano, Michael S.

2007-03-01

331

Electron transport properties of carbon nanotube-graphene contacts  

NASA Astrophysics Data System (ADS)

The properties of carbon nanotube-graphene junctions are investigated with first-principles electronic structure and electron transport calculations. Contact properties are found to be key factors in determining the performance of nanotube based electronic devices. In a typical single-walled carbon nanotube-metal junction, there is a p-type Schottky barrier of up to ˜0.4 eV which depends on the nanotube diameter. Calculations of the Schottky barrier height in carbon nanotube-graphene contacts indicate that low barriers of 0.09 eV and 0.04 eV are present in nanotube-graphene contacts ((8,0) and (10,0) nanotubes, respectively). Junctions with a finite contact region are investigated with simulations of the current-voltage characteristics. The results suggest the suitability of the junctions for applications and provide insight to explain recent experimental findings.

Cook, Brandon G.; French, William R.; Varga, Kálmán

2012-10-01

332

Geometrical effects of ( 14N@C 60) 2, 14N@C 60 and C 59N endohedral fullerenes within single-walled carbon nanotube as peapods on electronic structure and magnetic properties  

NASA Astrophysics Data System (ADS)

Design of spin labels inside for possible molecular spintronics, which contains of 1D spin chain filling single-walled carbon nanotube (SWCNT) with magnetic endohedral fullerenes of ( 14N@C 60) 2, 14N@C 60 and C 59N has been proposed. Electronic structure and magnetic properties of ( 14N@C 60) 2-SWCNT, 14N@C 60-SWCNT, 14N@C 60 and C 59N were characterized. Geometrical effect of ( 14N@C 60) 2, 14N@C 60 and C 59N within SWCNT on chemical shift of 13C, principal g-tensor, A-tensor in hfc of nitrogen atom and excited state transition was investigated by ab-initio density functional theory. The magnetic properties would be originated in the spin density distribution with ?-electron interaction between encapsulated fullerenes and inner surface on SWCNT and extent of charge transfer.

Suzuki, Atsushi; Oku, Takeo

2011-09-01

333

Carbon nanotube initiated formation of carbon nanoscrolls Zhao Zhang1  

E-print Network

alkali metals, and the resulting exfoliated graphite sheets can curl into scrolls upon sonication.2 years has enabled the fabrication of graphene monolayers via mechanical exfoliation.13 Recent experi graphene on a substrate, initiated by a carbon nanotube CNT . The rolling of graphene into a CNS

Li, Teng

334

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

335

Degradation of multiwall carbon nanotubes by bacteria.  

PubMed

Understanding the environmental transformation of multiwall carbon nanotubes (MWCNTs) is important to their life cycle assessment and potential environmental impacts. We report that a bacterial community is capable of degrading (14)C-labeled MWCNTs into (14)CO2 in the presence of an external carbon source via co-metabolism. Multiple intermediate products were detected, and genotypic characterization revealed three possible microbial degraders: Burkholderia kururiensis, Delftia acidovorans, and Stenotrophomonas maltophilia. This result suggests that microbe/MWCNTs interaction may impact the long-term fate of MWCNTs. PMID:23859846

Zhang, Liwen; Petersen, Elijah J; Habteselassie, Mussie Y; Mao, Liang; Huang, Qingguo

2013-10-01

336

Frontiers of the Physics of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes entered the scene of materials physics about 20 years ago, exhibiting unusual structures and properties stemming from their strong sp2 carbon bonds, their lower mass density, their very large length-to-diameter ratio, and their ability to be either semiconducting or metallic depending on their tube diameter and the orientation of their in-plane hexagons relative to their tube axis. You might ask what potential applications could be envisioned for such unusual nano structures, and what practical application have in fact been realized to date. This will be the focus of my presentation.

Dresselhaus, Mildred

2013-03-01

337

From carbon nanotubes to carbon atomic chains  

Microsoft Academic Search

Carbyne is a linear allotrope of carbon. It is formed by a linear arrangement of carbon atoms with sp-hybridization. We present a reliable and reproducible experiment to obtain these carbon atomic chains using few-layer-graphene (FLG) sheets and a HRTEM. First the FLG sheets were synthesized from worm-like exfoliated graphite and then drop-casted on a lacey-carbon copper grid. Once in the

Gilberto Casillas García; Weijia Zhang; Miguel José-Yacamán

2010-01-01

338

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

339

The effect of carbon nanotubes on chiral chemical reactions  

NASA Astrophysics Data System (ADS)

The intrinsic helicity of carbon nanotubes influences the formation of chiral molecules in chemical reactions. A racemic mixture of P and M enantiomers of nanotubes affects the enantiomeric excess of the products of the autocatalytic Soai reaction proportional to the amount of nanotubes added in the reaction mixture. An intermediate complex formed between the nanotube and the organometallic reagent is essential and explains the observed correlation between the enantiomeric distribution of products and the curvature of the carbon nanostructure. This Letter establishes a key mechanism for harnessing the helicity of nanoscale carbon surfaces for preparative organic reactions.

Rance, Graham A.; Miners, Scott A.; Chamberlain, Thomas W.; Khlobystov, Andrei N.

2013-02-01

340

Continuous diffraction patterns from circular arrays of carbon nanotubes  

NASA Astrophysics Data System (ADS)

We report the remarkable diffraction effects produced from circular patterned arrays of multiwalled carbon nanotubes (MWCNTs). Highly ordered circular arrays of multiwalled carbon nanotubes (with inter-nanotube spacings of 633 nm) display optical dispersion effects similar to compact discs. These arrays display remarkable diffraction patterns in the far field which are spatially continuous. High quality diffraction patterns were obtained experimentally which are in excellent agreement with the theoretical calculations. The achieved continuous diffraction patterns pave the way towards the utilization of engineered carbon nanotube arrays in applications like three dimensional holograms.

Butt, Haider; Butler, Tim; Montelongo, Yunuen; Rajesekharan, Ranjith; Wilkinson, Timothy D.; Amaratunga, Gehan A. J.

2012-12-01

341

High sensitivity carbon nanotube based electrochemiluminescence sensor array  

Microsoft Academic Search

Ink jet printed carbon nanotube forest arrays capable of detecting picomolar concentrations of immunoglobulin G (IgG) using electrochemiluminescence (ECL) are described. Patterned arrays of vertically aligned single walled carbon nanotube (SWCNT) forests were printed on indium tin oxide (ITO) electrodes. Capture anti-IgG antibodies were then coupled through peptide bond formation to acidic functional groups on the vertical nanotubes. IgG immunoassays

Anita Venkatanarayanan; Karl Crowley; Elena Lestini; Tia E. Keyes; James F. Rusling; Robert J. Forster

342

Carbon nanotubes: from nano test tube to nano-reactor.  

PubMed

Confinement of molecules and atoms inside carbon nanotubes provides a powerful strategy for studying structures and chemical properties of individual molecules at the nanoscale. In this issue of ACS Nano, Allen et al. explore the nanotube as a template leading to the formation of unusual supramolecular and covalent structures. The potential of carbon nanotubes as reactors for synthesis on the nano- and macroscales is discussed in light of recent studies. PMID:22200191

Khlobystov, Andrei N

2011-12-27

343

CVD Growth of Single-Walled Carbon Nanotubes Shigeo Maruyama  

E-print Network

CVD Growth of Single-Walled Carbon Nanotubes Shigeo Maruyama Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan maruyama@photon.t.u-tokyo.ac.jp CVD growth of single-walled carbon nanotubes (SWNTs) will be discussed with recent alcohol CVD experiments incorporating nitrogen, molecular

Maruyama, Shigeo

344

MOLECULAR DYNAMICS SIMULATIONS OF CARBON NANOTUBE-BASED OSCILLATORS  

E-print Network

MOLECULAR DYNAMICS SIMULATIONS OF CARBON NANOTUBE-BASED OSCILLATORS HAVING TOPOLOGICAL DEFECTSÃ?Wales defects on the oscillatory behavior of (5,5)/(10,10) carbon nanotube-based oscillator are studied using NVE molecular dynamics simulations. Results show that defects reduce stability of the oscillators. E

Bhattacharya, Baidurya

345

Generation of a Carbon Nanotube-Cyclodextrin Complex.  

National Technical Information Service (NTIS)

In this study the intermolecular interactions of small diameter ((caret) 0. 7 nm) carbon nanotubes and gamma-cyclodextrin were examined. Four samples of gamma cyclodextrin and HiPco carbon nanotubes were prepared. The fast, by grinding the tubes and the c...

G. F. Farrell, G. Chambers, A. B. Dalton, E. Cummins, M. McNamara

2001-01-01

346

Random telegraph signals and noise behaviors in carbon nanotube transistors  

E-print Network

bias for a larger absolute drain-source bias in a carbon nanotube transistor. Its mechanism-carbon nanotube junctions.5­8 Both gate bias and drain-source bias could strongly modulate the width and thus and metallic CNTs confirming the generality and importance of RTS in CNT-FETs. Back side gated CNT

Zhou, Chongwu

347

Impurity scattering in metallic carbon nanotubes with superconducting pair potentials  

E-print Network

Impurity scattering in metallic carbon nanotubes with superconducting pair potentials Kikuo of the superconducting pair potential on the impurity scattering processes in metallic carbon nanotubes are studied theoretically. The backward scattering of electrons vanishes in the normal state. In the presence

Harigaya, Kikuo

348

Aligned carbon nanotubes on quartz substrate for liquid gated biosensing  

Microsoft Academic Search

A facile and high performance biosensing platform using aligned carbon nanotubes on quartz substrate is reported in this communication. Single walled carbon nanotubes are grown on quartz substrates by a chemical vapor deposition process and are characterized with field emission scanning electron microscopy and atomic force microscopy in order to verify the quality of the material. The quartz substrate is

Al. Palaniappan; W. H. Goh; J. N. Tey; I. P. M. Wijaya; S. M. Moochhala; B. Liedberg; S. G. Mhaisalkar

2010-01-01

349

8B. Nano-Biotechnology Aptabodies immobilized on carbon nanotubes-  

E-print Network

8B. Nano-Biotechnology OP8B-1 Aptabodies immobilized on carbon nanotubes- new artificial receptor of carbon nanotube layers (MWNTs) by electro- polymerisation and for detection thrombin ­ aptamer compounds, which is comparable with affinity of antibodies. So far used aptamers were based on single

Gürel, Levent

350

Apparatus for the laser ablative synthesis of carbon nanotubes  

DOEpatents

An RF-induction heated side-pumped synthesis chamber for the production of carbon nanotubes. Such an apparatus, while capable of producing large volumes of carbon nanotubes, concurrently provides a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization.

Smith, Michael W. (Newport News, VA); Jordan, Kevin (Newport News, VA)

2010-02-16

351

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.

352

Nanoscale pressure effects in individual double-wall carbon nanotubes  

Microsoft Academic Search

We use the signal from the internal tubes of double-wall carbon nanotubes as an ideal pressure reference. The intensity associated with the G band of the external tubes is shown to be related to the interaction of the pressure medium and the carbon nanotube. We observe clear pressure medium dependent pressure coefficients of the Raman G band using atomic argon,

P. Puech; E. Flahaut; A. Sapelkin; H. Hubel; D. J. Dunstan; G. Landa; W. S. Bacsa

2006-01-01

353

Strain controlled thermomutability of single-walled carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes are superior materials for thermal management and phononic device use due to their extremely high thermal conductivity and unique one-dimensional geometry. Here we report a systematic investigation of the effects of mechanical tensile, compressive and torsional strain on the thermal conductivity of single-walled carbon nanotubes using molecular dynamics simulation. In contrast to conventional predictions for solids, an unexpected

Zhiping Xu; Markus J. Buehler

2009-01-01

354

EXCITON BEHAVIOR IN CARBON NANOTUBES: DIELECTRIC SCREENING AND DECAY DYNAMICS  

E-print Network

BEHAVIOR IN CARBON NANOTUBES: DIELECTRIC SCREENING AND DECAY DYNAMICS by ANDREW GERALD WALSH B. S., Cornell DYNAMICS (Order No. ) ANDREW GERALD WALSH Boston University Graduate School of Arts and Sciences, 2009' & $ % EXCITON BEHAVIOR IN CARBON NANOTUBES: DIELECTRIC SCREENING AND DECAY DYNAMICS ANDREW GERALD

355

Author's personal copy Producing superior composites by winding carbon nanotubes  

E-print Network

Author's personal copy Producing superior composites by winding carbon nanotubes onto a mandrel for processing high-performance carbon nanotube (CNT)/poly(vinyl alco- hol) (PVA) composites by coupling University, Raleigh, NC 27695, USA c Suzhou Institute of Nano-Tech and Nano-Bionics, Suzhou 215123, China d

Zhu, Yuntian T.

356

Preparation of Carbon Nanotube Bioconjugates for Biomedical Applications  

Microsoft Academic Search

Biomedical applications of carbon nanotubes have attracted much attention in recent years. Here, we summarize our previously developed protocols for functionalization and bioconjugation of single wall carbon nanotubes (SWNTs) for various biomedical applications including biological imaging, sensing and drug delivery. Sonication of SWNTs in solutions of phospholipid-polyethylene glycol (PL-PEG) is our most commonly used protocol of SWNT functionalization. Compared to

Zhuang Liu; Scott Tabakman; Zhuo Chen; Hongjie Dai

2009-01-01

357

EMI shielding evaluations of carbon nanotube based coatings and applications  

Microsoft Academic Search

Electromagnetic interference (EMI) shielding coatings based on carbon nanotube (CNT) has been prepared and evaluated. The electromagnetic shielding effectiveness is measured using planar material fixture method from 10MHz to 3 GHz and with free space method in the range of 3 GHz to 18 GHz. The results show that carbon nanotube based coating is effective in providing EMI shielding in

Ping Li; Yueyan Shan; Lie Liu; Junhong Deng; Ong Guat Choon; Xijiang Yin

2012-01-01

358

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

359

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

360

Carbon Nanotubes and Carbon Nanotube Fiber Sensors: Growth, Processing and Characterization  

Microsoft Academic Search

With multiple outstanding properties, such as high Young's modulus, high strength, good thermal conductivity and electrical conductivity, carbon nanotube (CNT) has been considered as a new generation of material that has many potential applications in many fields. One obstacle that stands in the way of applying CNTs in the real world is the limited growth length. Catalyst instability is one

Haibo Zhao

2010-01-01

361

Multifunctional Carbon Nanotube Sensors for Environmental Monitoring  

NASA Astrophysics Data System (ADS)

As a one dimensional material, a Single-walled Carbon Nanotube (SWNT) is made of a rolled up graphene sheet. With a diameter of 1˜2 nm, the SWNTs exhibit many unique properties, such as high aspect ratios, ballistic carrier transport, high mechanical strength and thermal stability. These properties enable SWNTs to have superior performances in various applications including electronics and sensors. SWNT based sensors are extremely sensitive to slight electrostatic changes in their environment and have a fast response where conductance of an SWNT is observed to change in less than 2 sec upon exposure. In addition, SWNT sensors have size advantage over traditional sensors. Hence, SWNTs have been widely explored as active sensing elements for chemical and biomolecule detection. Despite high sensitivities observed from nanotube sensors, one drawback is their lack of selectivity. The conductance of SWNTs is susceptible to many gas molecules in air, including oxygen and moisture which are abundantly present in the ambient environment. Due to this nonspecificity, the presence of any type of gas vapors can possibly interfere with the induced signals from the target gas vapors and hence reduce S/N ratio during detection. To minimize the effects of undesirable interference signals from the environment, several functionalization methods have been developed to customize the affinities of SWNTs to specific targets, including metal nano particles, conducting polymers and biomolecules. The objective of this thesis is to utilize SWNTs in environmental applications. The proposed research topics include: investigating the sensing characteristics of RNA oligomers on carbon nanotubes; analyzing the sensing characteristics of DNA with different sequence lengths on carbon nanotubes; integration of DNA decorated SWNTs onto CMOS chip for toxic and explosive gas monitoring; building nanosensor array based on multi-functionalized SWNTs for air quality monitoring and exploring the sensing mechanism of DNA decorated SWNTs; integration of SWNTs inside microfluidic channels for water quality monitoring. The essential procedures are composed of device fabrication (post CMOS and zincation process for CMOS chip; photolithography for silicon chip), SWNTs assembly, functionalization of SWNTs by DNA or RNA molecules, building setup for signal acquisition and processing and the measurement of sensing response to gases and liquids. These investigations will pave the way toward remote-controlled sensing arrays made of functionalized SWNTs for air and water quality monitoring. Finally a nanotube based electronic device embedded in flexible and stretchable polymer thin films is demonstrated which shows great potential to encapsulate SWNT based sensors inside flexible and stretchable substrates for structural health monitoring.

Liu, Yu

362

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

363

Single-walled carbon nanotubes with DNA recognition  

NASA Astrophysics Data System (ADS)

Two methods for attaching DNA to oxidized single-walled carbon nanotubes either in organic solvent or aqueous solution are described. The sites of DNA attachment to the nanotubes have been verified by binding gold nanoparticles modified with DNA of complementary sequence to the DNA-modified nanotubes, and imaging with TEM. The gold nanoparticles appear on the tips of the nanotubes, and at isolated positions (defects) on the sidewalls. The methods provide versatility for the modification of nanotubes with DNA for their directed assembly, or for their composites with gold nanoparticles, into nanoscale devices.

Yang, Wenrong; Moghaddam, Minoo J.; Taylor, Sarah; Bojarski, Barbara; Wieczorek, Lech; Herrmann, Jan; McCall, Maxine J.

2007-08-01

364

Thermophoretic motion of water nanodroplets confined inside carbon nanotubes.  

PubMed

We study the thermophoretic motion of water nanodroplets confined inside carbon nanotubes using molecular dynamics simulations. We find that the nanodroplets move in the direction opposite the imposed thermal gradient with a terminal velocity that is linearly proportional to the gradient. The translational motion is associated with a solid body rotation of the water nanodroplet coinciding with the helical symmetry of the carbon nanotube. The thermal diffusion displays a weak dependence on the wetting of the water-carbon nanotube interface. We introduce the use of the moment scaling spectrum (MSS) in order to determine the characteristics of the motion of the nanoparticles inside the carbon nanotube. The MSS indicates that affinity of the nanodroplet with the walls of the carbon nanotubes is important for the isothermal diffusion and hence for the Soret coefficient of the system. PMID:19105740

Zambrano, Harvey A; Walther, Jens H; Koumoutsakos, Petros; Sbalzarini, Ivo F

2009-01-01

365

Superconductivity in 4-Angstrom carbon nanotubes--a short review.  

PubMed

We give an up-to-date review of the superconducting phenomena in 4-Angstrom carbon nanotubes embedded in aligned linear pores of the AlPO(4)-5 (AFI) zeolite, first discovered in 2001 as a fluctuation Meissner effect. With the introduction of a new approach to sample synthesis around 2007, new data confirming the superconductivity have been obtained. These comprise electrical, specific heat, and magnetic measurements which together yield a consistent yet complex physical picture of the superconducting state, largely owing to the one-dimensional (1D) nature of the 4-Angstrom carbon nanotubes. For the electrical transport characteristics, two types of superconducting resistive behaviors were reproducibly observed in different samples. The first type is the quasi 1D fluctuation superconductivity that exhibits a smooth resistance drop with decreasing temperature, initiating at 15 K. At low temperatures the differential resistance also shows a smooth increase with increasing bias current (voltage). Both are unaffected by an applied magnetic field up to 11 Tesla. These manifestations are shown to be consistent with those of a quasi 1D superconductor with thermally activated phase slips as predicted by the Langer-Ambegaokar-McCumber-Halperin (LAMH) theory. The second type is the quasi 1D to 3D superconducting crossover transition, which was observed to initiate at 15 K with a slow resistance decrease switching to a sharp order of magnitude drop at ?7.5 K. The latter exhibits anisotropic magnetic field dependence and is attributed to a Berezinskii-Kosterlitz-Thouless (BKT)-like transition that establishes quasi-long-range order in the plane transverse to the c-axis of the aligned nanotubes, thereby mediating a 1D to 3D crossover. The electrical data are complemented by magnetic and thermal specific heat bulk measurements. By using both the SQUID VSM and the magnetic torque technique, the onset of diamagnetism was observed to occur at ?15 K, with a rapid increase of the diamagnetic moment below ?7 K. The zero-field-cooled and field-cooled branches deviated from each other below 7 K, indicating the establishment of a 3D Meissner state with macroscopic phase coherence. The superconductivity is further supported by the specific heat measurements, which show an anomaly with onset at 15 K and a peak at 11-12 K. In the 3D superconducting state, the nanotube arrays constitute a type-II anisotropic superconductor with H(c1)? 60 to 150 Oe, coherence length ?? 5 to 15 nm, London penetration length ?? 1.5 µm, and Ginzburg-Landau ?? 100. We give a physical interpretation to the observed phenomena and note the challenges and prospects ahead. PMID:22105840

Wang, Zhe; Shi, Wu; Lortz, Rolf; Sheng, Ping

2012-01-01

366

Charge-Transfer Induced Magnetic Field Effects of Nano-Carbon Heterojunctions  

E-print Network

Room temperature magnetic field effects have not been definitively observed in either single-walled carbon nanotubes (SWCNTs) or C60 under a small magnetic field due to their weak hyperfine interaction and slight difference of g-factor between...

Qin, Wei; Gong, Maogang; Shastry, Tejas; Hersam, Mark C.; Ren, Sheqiang

2014-08-22

367

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

368

Influence of AC Electric Field on Dispersion of Carbon Nanotubes in Liquids  

Microsoft Academic Search

Production processes for carbon nanotubes commonly produce mixtures of solid morphologies that are mechanically entangled or that self?associate into aggregates. The entangled or aggregated carbon nanotubes often need to be dispersed in liquids for further applications. The authors propose an innovative dispersion method for carbon nanotubes by which an AC electric field is applied to suspensions of carbon nanotubes. The

Zhang Chan; Shi Lei; Liang Ji

2006-01-01

369

Nanoscale carbon nanotube motor schematics and simulations for micro-electro-mechanical machines  

Microsoft Academic Search

We investigated nanoscale engine schematics composed of a carbon nanotube oscillator, motor, channel, nozzle, etc. For the fluidic gas driven carbon nanotube motor, the origination of the torque was the friction between the carbon nanotube surface and the fluidic gases. The density and flow rate of the working gas or liquid are very important for the carbon nanotube motor. When

Jeong Won Kang; Ho Jung Hwang

2004-01-01

370

CARBON NANOTUBE TRANSISTORS, SENSORS, AND A Dissertation  

E-print Network

and peak mobility scales with nanotube diameters also, in a linear fashion and quadratic fashion bilayers near nanotubes is confirmed by probing the diffusion of lipid molecules. Nanotubes do not slow

McEuen, Paul L.

371

Genotoxicity and carcinogenicity risk of carbon nanotubes.  

PubMed

Novel materials are often commercialized without a complete assessment of the risks they pose to human health because such assessments are costly and time-consuming; additionally, sometimes the methodology needed for such an assessment does not exist. Carbon nanotubes have the potential for widespread application in engineering, materials science and medicine. However, due to the needle-like shape and high durability of multiwalled carbon nanotubes (MWCNTs), concerns have been raised that they may induce asbestos-like pathogenicity when inhaled. Indeed, experiments in rodents supported this hypothesis. Notably, the genetic alterations in MWCNT-induced rat malignant mesothelioma were similar to those induced by asbestos. Single-walled CNTs (SWCNTs) cause mitotic disturbances in cultured cells, but thus far, there has been no report that SWCNTs are carcinogenic. This review summarizes the recent noteworthy publications on the genotoxicity and carcinogenicity of CNTs and explains the possible molecular mechanisms responsible for this carcinogenicity. The nanoscale size and needle-like rigid structure of CNTs appear to be associated with their pathogenicity in mammalian cells, where carbon atoms are major components in the backbone of many biomolecules. Publishing adverse events associated with novel materials is critically important for alerting people exposed to such materials. CNTs still have a bright future with superb economic and medical merits. However, appropriate regulation of the production, distribution and secondary manufacturing processes is required, at least to protect the workers. PMID:23751780

Toyokuni, Shinya

2013-12-01

372

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

373

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

374

Micropreconcentration units based on carbon nanotubes (CNT)  

Microsoft Academic Search

Carbon nanotubes (CNT) have some highly desirable sorbent characteristics which make them attractive for a variety of analytical\\u000a applications. High adsorption capacity and rapid desorbability make CNT excellent candidates for micro-scale devices for gas\\u000a and liquid-phase analysis. In gas-phase analysis one can implement a micro-concentrator or a micro-sorbent trap, which have\\u000a been used in a variety of on-line chromatography and

Chaudhery Mustansar Hussain; Somenath Mitra

2011-01-01

375

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

376

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

377

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

378

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

379

Nanotechnology: Carbon nanotubes with DNA recognition  

NASA Astrophysics Data System (ADS)

Since the discovery of their one-dimensional electronic band structure, the leading candidate that has emerged for nanodevice applications is single-walled carbon nanotubes (SWNTs) . Here we unite their unique properties with the specific molecular-recognition features of DNA by coupling SWNTs to peptide nucleic acid (PNA, an uncharged DNA analogue) and hybridizing these macromolecular wires with complementary DNA. Our findings provide a new, versatile means of incorporating SWNTs into larger electronic devices by recognition-based assembly, and of using SWNTs as probes in biological systems by sequence-specific attachment.

Williams, Keith A.; Veenhuizen, Peter T. M.; de la Torre, Beatriz G.; Eritja, Ramon; Dekker, Cees

2002-12-01

380

Decorating carbon nanotubes with nickel nanoparticles  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) were decorated with Ni clusters by thermal evaporation. It is shown that the CNT decoration with Ni varies from well-organized clusters to the complete coverage of the surface resulting in electronic charge transfer and formation of Ni-C bonds at the interface between these two materials, depending on the evaporated amount of Ni. The Ni-CNTs interaction induces an increase in the metallicity of the system suggesting that CNTs decorated with metal atoms can be a good candidate as template for production of metal nanowires.

Bittencourt, C.; Felten, A.; Ghijsen, J.; Pireaux, J. J.; Drube, W.; Erni, R.; Van Tendeloo, G.

2007-03-01

381

Carbon Nanotube Integration with a CMOS Process  

PubMed Central

This work shows the integration of a sensor based on carbon nanotubes using CMOS technology. A chip sensor (CS) was designed and manufactured using a 0.30 ?m CMOS process, leaving a free window on the passivation layer that allowed the deposition of SWCNTs over the electrodes. We successfully investigated with the CS the effect of humidity and temperature on the electrical transport properties of SWCNTs. The possibility of a large scale integration of SWCNTs with CMOS process opens a new route in the design of more efficient, low cost sensors with high reproducibility in their manufacture. PMID:22319330

Perez, Maximiliano S.; Lerner, Betiana; Resasco, Daniel E.; Pareja Obregon, Pablo D.; Julian, Pedro M.; Mandolesi, Pablo S.; Buffa, Fabian A.; Boselli, Alfredo; Lamagna, Alberto

2010-01-01

382

Computational Nanotechnology of Materials, Devices, and Machines: Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

The mechanics and chemistry of carbon nanotubes have relevance for their numerous electronic applications. Mechanical deformations such as bending and twisting affect the nanotube's conductive properties, and at the same time they possess high strength and elasticity. Two principal techniques were utilized including the analysis of large scale classical molecular dynamics on a shared memory architecture machine and a quantum molecular dynamics methodology. In carbon based electronics, nanotubes are used as molecular wires with topological defects which are mediated through various means. Nanotubes can be connected to form junctions.

Srivastava, Deepak; Kwak, Dolhan (Technical Monitor)

2000-01-01

383

Thin micropatterned multi-walled carbon nanotube films for electrodes  

NASA Astrophysics Data System (ADS)

Micropatterned electrodes based on thin multi-walled carbon nanotube films are grown by catalytic chemical vapour deposition on lithographically defined quartz and Inconel alloy substrates. The electrical contact at the interface between the root of the nanotube arrays and the thin Ti hardmask layer on the quartz surface is found to be poor disabling proper capacitive characteristics. On the other hand, nanotube-Inconel electrodes show low series resistance and good electric double layer capacitor operation close to that of ideal devices. Patterning of the electrodes enhances both specific capacitance and power in reference to non-patterned bulk carbon nanotube film electrodes.

Halonen, Niina; Mäklin, Jani; Rautio, Anne-Riikka; Kukkola, Jarmo; Uusimäki, Antti; Toth, Geza; Reddy, Leela Mohana; Vajtai, Robert; Ajayan, Pulickel M.; Kordas, Krisztian

2013-09-01

384

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

385

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

PubMed Central

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. PMID:23066502

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

2012-01-01

386

A Carbon Nanotube Cable for a Space Elevator  

NASA Astrophysics Data System (ADS)

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 estimated. For this calculation only simple high school physics is necessary. The results, the same as known from experimental data, show that carbon nanotubes could be, at least hypothetically, a possible material for construction of a space elevator cable.

Bochní?ek, Zden?k

2013-11-01

387

Nanoscale carbon nanotube motor schematics and simulations for micro-electro-mechanical machines  

NASA Astrophysics Data System (ADS)

We investigated nanoscale engine schematics composed of a carbon nanotube oscillator, motor, channel, nozzle, etc. For the fluidic gas driven carbon nanotube motor, the origination of the torque was the friction between the carbon nanotube surface and the fluidic gases. The density and flow rate of the working gas or liquid are very important for the carbon nanotube motor. When multi-wall carbon nanotubes with very low rotating energy barriers are used for carbon nanotube motors, the fluidic gas driven carbon nanotube motors can be effectively operated and controlled by the gas flow rates. The variations of the flux were the same as the variations of the carbon nanotube oscillator. Although the carbon nanotube oscillator continually vibrated, since the angular velocity of the motor was saturated at a constant value, the speed of the nanoscale engine could be controlled by the frequency of the carbon nanotube oscillator below the maximum speed.

Kang, Jeong Won; Hwang, Ho Jung

2004-11-01

388

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

389

Superconducting characteristics of 4-? carbon nanotube–zeolite composite  

PubMed Central

We have fabricated nanocomposites consisting of 4-? carbon nanotubes embedded in the 0.7-nm pores of aluminophosphate-five (AFI) zeolite that display a superconducting specific heat transition at 15 K. MicroRaman spectra of the samples show strong and spatially uniform radial breathing mode (RBM) signals at 510 cm?1 and 550 cm?1, characteristic of the (4, 2) and (5, 0) nanotubes, respectively. The specific heat transition is suppressed at >2 T, with a temperature dependence characteristic of finite-size effects. Comparison with theory shows the behavior to be consistent with that of a type II BCS superconductor, characterized by a coherence length of 14 ± 2 nm and a magnetic penetration length of 1.5 ± 0.7 ?m. Four probe and differential resistance measurements have also indicated a superconducting transition initiating at 15 K, but the magnetoresistance data indicate the superconducting network to be inhomogeneous, with a component being susceptible to magnetic fields below 3 T and other parts capable of withstanding a magnetic field of 5 T or beyond. PMID:19369206

Lortz, Rolf; Zhang, Qiucen; Shi, Wu; Ye, Jian Ting; Qiu, Chunyin; Wang, Zhe; He, Hongtao; Sheng, Ping; Qian, Tiezheng; Tang, Zikang; Wang, Ning; Zhang, Xixiang; Wang, Jiannong; Chan, Che Ting

2009-01-01

390

A cell nanoinjector based on carbon nanotubes  

SciTech Connect

Technologies for introducing molecules into living cells are vital for probing the physical properties and biochemical interactions that govern the cell's behavior. Here we report the development of a nanoscale cell injection system-termed the nanoinjector-that uses carbon nanotubes to deliver cargo into cells. A single multi-walled carbon nanotube attached to an atomic force microscope tip was functionalized with cargo via a disulfide-based linker. Penetration of cell membranes with this 'nanoneedle', followed by reductive cleavage of the disulfide bonds within the cell's interior, resulted in the release of cargo inside the cells. The capability of the nanoinjector was demonstrated by injection of protein-coated quantum dots into live human cells. Single-particle tracking was employed to characterize the diffusion dynamics of injected quantum dots in the cytosol. This new technique causes no discernible membrane or cell damage, and can deliver a discrete number of molecules to the cell's interior without the requirement of a carrier solvent.

Chen, Xing; Kis, Andras; Zettl, Alex; Bertozzi, Carolyn R.

2007-01-30

391

Design and Characterization of Carbon Nanotube Nanocomposites  

NASA Technical Reports Server (NTRS)

Revolutionary design concepts in future aerospace vehicles will depend on extraordinary material properties to permit significant reduction of mass and size of components, while imparting intelligence. Due to their combination of remarkable electrical and mechanical properties, carbon nanotubes (CNT) are expected to enable this paradigm shift in design concepts. However, significant challenges still exist in translating these CNT properties into the macrostructures required for future generations of aerospace vehicles. While an accepted route for making the leap from nanostructures to useful macrostructures has not been fully charted, this paper will give an overview of the approach taken by some researchers at NASA Langley Research Center to sort out issues involved in the development of CNT nanocomposites for multifunctional structures. Specifically, the dispersion of carbon nanotubes in polymer matrices, characterization of nanocomposites, the role of quantum computation in providing guidance for processing and the use of computational analysis in data interpretation will be covered. Significant improvements in mechanical and electrical properties of CNT nanocomposites with very low loadings of CNTs are described and lend credence to the potential for using CNTs in achieving technological leaps in composite development.

Siochi, Emilie J.; Lillehei, Peter T.; Wise, Kristopher E.; Park, Cheol; Rouse, Jason H.

2003-01-01

392

Exciton Dynamics in Semiconducting Carbon Nanotubes  

SciTech Connect

We report femtosecond transient absorption spectroscopic study on the (6, 5) single-walled carbon nanotubes and the (7, 5) inner tubes of a dominant double-walled carbon nanotube species. We found that the dynamics of exciton relaxation probed at the first transition-allowed state (E11) of a given tube type exhibits a markedly slower decay when the second transition-allowed state (E22) is excited than that measured by exciting its first transition-allowed state (E11). A linear intensity dependence of the maximal amplitude of the transient absorption signal is found for the E22 excitation, whereas the corresponding amplitude scales linearly with the square root of the E11 excitation intensity. Theoretical modeling of these experimental findings was performed by developing a continuum model and a stochastic model with explicit consideration of the annihilation of coherent excitons. Our detailed numerical simulations show that both models can reproduce reasonably well the initial portion of decay kinetics measured upon the E22 and E11 excitation of the chosen tube species, but the stochastic model gives qualitatively better agreement with the intensity dependence observed experimentally than those obtained with the continuum model.

Graham, Matt [University of California, Berkeley; Chmeliov, Javgenij [Vilnius University, Lithuania; Ma, Yingzhong [ORNL; Shinohara, Nori [Nagoya University, Japan; Green, Alexander A. [Northwestern University, Evanston; Hersam, Mark C. [Northwestern University, Evanston; Valkunas, Leonas [Vilnius University, Lithuania; Fleming, Graham [University of California, Berkeley

2010-01-01

393

Electron spin relaxation in carbon nanotubes: Dyakonov-Perel mechanism  

NASA Astrophysics Data System (ADS)

The long standing problem of unaccountable short spin relaxation in carbon nanotubes (CNT) meets a disclosure in terms of curvature-mediated spin-orbital interaction that leads to spin fluctuating precession analogous to Dyakonov-Perel mechanism. Strong anisotropy imposed by arbitrary directed magnetic field has been taken into account in terms of extended Bloch equations. Especially, stationary spin current through CNT can be controlled by spin-flip processes with relaxation time as less as 150 ps, the rate of transversal polarization (i.e. decoherence) runs up to 1/(70 ps) at room temperature while spin interference of the electrons related to different valleys can be responsible for shorter spin dephasing. Dependencies of spin-relaxation parameters on magnetic field strength and orientation, CNT curvature and chirality have been analyzed.

Semenov, Yuriy; Zavada, John; Kim, Ki Wook

2010-03-01

394

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

395

Amphiphilic Polyelectrolytes Solubilize Carbon Nanotubes in Aqueous Dispersions  

NASA Astrophysics Data System (ADS)

A convenient procedure for forming stable suspensions of SWNT's in water and water/DMF solutions is reported. The dispersion process is effective, simple, and universal. It can be applied to different types of single-walled carbon nanotubes (SWNT's) as well as multi walled carbon nanotubes (MWNT's). The stability of SWNT suspensions was achieved by adsorbing an amphiphilic cationic [poly (N-cetyl-4-vinylpyridinium bromide-co-N-ethyl-4-vinylpyridinium bromide-co- 4-vinylpyridine) (16/75/9)] polymer to carbon surface. The amphiphilic nature of the polymer plays a dual action in the functionalization and solubilization of the nanotubes. The hydrophobic alkyl pendent groups of the polymer bind strongly to the surface of the nanotubes, whereas the hydrophilic groups exposes the nanotubes to the solvent medium rendering them soluble in water. The frequency of the Raman radial breathing modes (RBM) and the carbon-carbon stretching mode (known as the G-band) of the nanotubes were seen to increase in the presence of the polymer. Some increase in the intensity of the Raman disorder band (the D-band) was also observed. Raman spectral observations indicate the strong binding of the copolymer to the nanotubes (wrapping) which causes the unbundling of the nanotubes, making them easier to disperse in aqueous solvents.

Gheith, Muhammed K.; Wicksted, James. P.; Sinani, Vladimir A.; Kotov, Nicholas A.; Yaroslavov, Alexander A.; Rakhnyanskaya, Anna A.; Mamedov, Arif A.

2004-03-01

396

Radial deformation of carbon nanotubes by van der Waals forces  

Microsoft Academic Search

THE discovery of carbon nanotubes1,2 has stimulated many theoretical studies of their physical properties3-12, and their bulk synthesis13 should soon make possible experimental measurements of these properties14. All studies so far have assumed that the nanotubes have perfect cylindrical symmetry. Here we show that van der Waals forces between adjacent nanotubes can deform them substantially, destroying this cylindrical symmetry. We

Rodney S. Ruoff; J. Tersoff; Donald C. Lorents; Shekhar Subramoney; Bryan Chan

1993-01-01

397

Ultrasonic Spraying of Carbon Nanotubes using Organic Solvents  

NASA Astrophysics Data System (ADS)

Because of their unique electrical and mechanical properties, thin films of carbon nanotubes have several potential applications, especially in the fields of organic electronics and photovoltaics. We present a method for spraying thin films of nanotubes that have been suspended in organic solvents N-methyl Pyrollidone (NMP) and N-Cyclohexyl-2-pyrrolidone (CHP). The sprayed nanotubes are randomly oriented, and films are transparent, conductive, and mechanically stable.

Willey, Anthony; Davis, Robert; Vanfleet, Richard

2012-10-01

398

Self-Assembly Experiments with PNA-Derivatized Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

We are conducting experiments to fabricate nanotube-based field effect transistors (FETs) using the molecular recognition properties of DNA. For this purpose, we have prepared single-walled carbon nanotubes derivatized with PNA (peptide nucleic acid, a DNA analog) and have studied their attachment to free, complementary DNA. We are currently examining the prospects for assembling devices by hybridization of the PNA-labeled nanotubes to DNA-functionalized electrodes.

den Dulk, Remco; Williams, Keith A.; Veenhuizen, Peter T. M.; de Koning, Martijn C.; Overhand, Mark; Dekker, Cees

2004-09-01

399

Waveguide-integrated electroluminescent carbon nanotubes  

E-print Network

Carbon based optoelectronic devices promise to revolutionize modern integrated circuits by combining outstanding electrical and optical properties into a unified technology. By coupling nanoelectronic devices to nanophotonic structures functional components such as nanoscale light emitting diodes, narrow-band thermal emitters, cavity controlled detectors and wideband electro optic modulators can be realized for chipscale information processing. These devices not only allow the light-matter interaction of low-dimensional systems to be studied, but also provide fundamental building blocks for high bandwidth on-chip communication. Here we demonstrate how light from an electrically-driven carbon-nanotube can be coupled directly into a photonic waveguide architecture. We realize wafer scale, broadband sources integrated with nanophotonic circuits allowing for propagation of light over centimeter distances. Moreover, we show that the spectral properties of the emitter can be controlled directly on chip with passive...

Khasminskaya, Svetlana; Flavel, Benjamin S; Pernice, Wolfram H P; Krupke, Ralph

2013-01-01

400

Aharonov–Bohm effect on exciton absorption of perpendicular light in carbon nanotubes  

Microsoft Academic Search

The Aharonov–Bohm effect on optical absorption of light polarized perpendicularly to the tube axis in semiconducting carbon nanotubes is studied by taking account of exciton and depolarization effect in an effective-mass approximation. The magnetic-flux dependence of the excitation energy is weak and quadratic around zero in contrast to the linear dependence for light polarized parallel to the axis.

Seiji Uryu; Tsuneya Ando

2007-01-01

401

Excitons in Carbon Nanotubes Revisited: Dependence on Diameter, Aharonov-Bohm Flux, and Strain  

Microsoft Academic Search

Optical spectra are calculated in semiconducting carbon nanotubes in the presence of magnetic flux and strain within a k{\\\\cdot}p scheme. The exciton absorption energies show an extra logarithmic dependence on the diameter after being scaled by the inverse diameter, coming from that of the enhancement of the band gaps. The exciton binding energy remains almost independent of the extra dependence.

Tsuneya Ando

2004-01-01

402

Aharonov-Bohm oscillation and chirality effect in optical activity of single-wall carbon nanotubes  

Microsoft Academic Search

We study the Aharonov-Bohm effect in the optical phenomena of single-wall carbon nanotubes (SWCN) and also their chirality dependence. Especially, we consider the natural optical activity as a proper observable and derive its general expression based on a comprehensive symmetry analysis, which reveals the interplay between the enclosed magnetic flux and the tubule chirality for arbitrary chiral SWCN. A quantitative

Fei Ye; Bing-Shen Wang; Zhao-Bin Su

2004-01-01

403

Aharonov Bohm effect on exciton absorption of perpendicular light in carbon nanotubes  

NASA Astrophysics Data System (ADS)

The Aharonov-Bohm effect on optical absorption of light polarized perpendicularly to the tube axis in semiconducting carbon nanotubes is studied by taking account of exciton and depolarization effect in an effective-mass approximation. The magnetic-flux dependence of the excitation energy is weak and quadratic around zero in contrast to the linear dependence for light polarized parallel to the axis.

Uryu, Seiji; Ando, Tsuneya

2007-12-01

404

Single-walled carbon nanotube buckypaper and mesophase pitch carbon\\/carbon composites  

Microsoft Academic Search

Carbon\\/carbon composites consisting of single-walled carbon nanotube (SWCNT) buckypaper (BP) and mesophase pitch resin have been produced through impregnation of BP with pitch using toluene as a solvent. Drying, stabilization and carbonization processes were performed sequentially, and repeated to increase the pitch content. Voids in the carbon\\/carbon composite samples decreased with increasing impregnation process cycles. Electrical conductivity and density of

Jin Gyu Park; Nam Gyun Yun; Young Bin Park; Richard Liang; Lloyd Lumata; James S. Brooks; Chuck Zhang; Ben Wang

2010-01-01

405

Single-walled carbon nanotube buckypaper and mesophase pitch carbon\\/carbon composites  

Microsoft Academic Search

Carbon\\/carbon composites consisting of single-walled carbon nanotube (SWCNT) buckypaper (BP) and mesophase pitch resin have been produced through impregnation of BP with pitch using toluene as a solvent. Drying, stabilization and carbonization processes were performed sequentially, and repeated to increase the pitch content. Voids in the carbon\\/carbon composite samples decreased with increasing impregnation process cycles. Electrical conductivity and density of

Jin Gyu Park; Nam Gyun Yun; Young Bin Park; Richard Liang; Lloyd Lumata; James Brooks; Chuck Zhang; Ben Wang

2011-01-01

406

Modeling Ballistic Current Flow in Carbon Nanotube Wires  

NASA Technical Reports Server (NTRS)

Experiments have shown carbon nanotubes (CNT) to be almost perfect conductors at small applied biases. The features of the CNT band structure, large velocity of the crossing subbands and the small number of modes that an electron close to the band center / Fermi energy can scatter into, are the reasons for the near perfect small bias conductance. We show that the CNT band structure does not help at large applied biases - electrons injected into the non crossing subbands can either be Bragg reflected or undergo Zener-type tunneling. This limits the current carrying capacity of CNT. We point out that the current carrying capacity of semiconductor quantum wires in the ballistic limit is different, owing to its band structure. The second aspect addressed is the relationship of nanotube chirality in determining the physics of metal-nanotube coupling. We show that a metallic-zigzag nanotube couples better than an armchair nanotube to a metal contact. This arises because in the case of armchair nanotubes, while the pi band couples well, the pi* band does not couple well to the metal. In the case of zigzag nanotube both crossing modes couple reasonably well to the metal. Many factors such as the role of curvature, strain and defects will play a role in determining the suitability of nanotubes as nanowires. From the limited view point of metal-nanotube coupling, we feel that metallic-zigzag nanotubes are preferable to armchair nanotubes.

Anantram, M. P.; Biegel, Bryan (Technical Monitor)

2001-01-01

407

Carbon nanotubes on carbon fibers: Synthesis, structures and properties  

NASA Astrophysics Data System (ADS)

The interface between carbon fibers (CFs) and the resin matrix in traditional high performance composites is characterized by a large discontinuity in mechanical, electrical, and thermal properties which can cause inefficient energy transfer. Due to the exceptional properties of carbon nanotubes (CNTs), their growth at the surface of carbon fibers is a promising approach to controlling interfacial interactions and achieving the enhanced bulk properties. However, the reactive conditions used to grow carbon nanotubes also have the potential to introduce defects that can degrade the mechanical properties of the carbon fiber (CF) substrate. In this study, using thermal chemical vapor deposition (CVD) method, high density multi-wall carbon nanotubes have been successfully synthesized directly on PAN-based CF surface without significantly compromising tensile properties. The influence of CVD growth conditions on the single CF tensile properties and carbon nanotube (CNT) morphology was investigated. The experimental results revealed that under high temperature growth conditions, the tensile strength of CF was greatly decreased at the beginning of CNT growth process with the largest decrease observed for sized CFs. However, the tensile strength of unsized CFs with CNT was approximately the same as the initial CF at lower growth temperature. The interfacial shear strength of CNT coated CF (CNT/CF) in epoxy was studied by means of the single-fiber fragmentation test. Results of the test indicate an improvement in interfacial shear strength with the addition of a CNT coating. This improvement can most likely be attributed to an increase in the interphase yield strength as well as an improvement in interfacial adhesion due to the presence of the nanotubes. CNT/CF also offers promise as stress and strain sensors in CF reinforced composite materials. This study investigates fundamental mechanical and electrical properties of CNT/CF using nanoindentation method by designed localized transverse compression at low loads (muN to mN) and small displacements (nm to a few mum). Force, strain, stiffness, and electrical resistance were monitored simultaneously during compression experiments. The results showed that CNT/CF possess a high sensing capability between force and resistance. Hysteresis in both force-displacement and resistance-displacement curves was observed with CNT/CF, but was more evident as maximum strain increased and did not depend on strain rate. Force was higher and resistance was lower during compression as compared to decompression. A model is proposed to explain hysteresis where van der Waals forces between deformed and entangled nanotubes hinder decompression of some of the compressed tubes that are in contact with each other. This study provides a new understanding of the mechanical and electrical behavior of CNT/CF that will facilitate usage as stress and strain sensors in both stand-alone and composite materials applications. A novel method for in situ observation of nano-micro scale CNT/CF mechanical behavior by SEM has been developed in this study. The results indicated that deformation of vertical aligned CNT (VACNT) forest followed a column-like bending mechanism under localized radial (axial) compression. No fracture was observed even at very high compression strain on a VACNT forest. In order to fully understand CNT forest properties, the viscous creep behavior of VACNT arrays grown on flat Si substrate has also been characterized using a nanoindentation method. Resulting creep response was observed to consist of a short transient stage and a steady state stage in which the rate of displacement was constant. The strain rate sensitivity depended on the density of the nanotube arrays, but it was independent of the ramping (compression) rate of the indenter.

Zhang, Qiuhong

408

Coupling carbon nanotube mechanics to a superconducting circuit  

PubMed Central

The quantum behaviour of mechanical resonators is a new and emerging field driven by recent experiments reaching the quantum ground state. The high frequency, small mass, and large quality-factor of carbon nanotube resonators make them attractive for quantum nanomechanical applications. A common element in experiments achieving the resonator ground state is a second quantum system, such as coherent photons or a superconducting device, coupled to the resonators motion. For nanotubes, however, this is a challenge due to their small size. Here, we couple a carbon nanoelectromechanical (NEMS) device to a superconducting circuit. Suspended carbon nanotubes act as both superconducting junctions and moving elements in a Superconducting Quantum Interference Device (SQUID). We observe a strong modulation of the flux through the SQUID from displacements of the nanotube. Incorporating this SQUID into superconducting resonators and qubits should enable the detection and manipulation of nanotube mechanical quantum states at the single-phonon level. PMID:22953042

Schneider, B. H.; Etaki, S.; van der Zant, H. S. J.; Steele, G. A.

2012-01-01

409

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

410

Rotational actuator of motor based on carbon nanotubes  

DOEpatents

A rotational actuator/motor based on rotation of a carbon nanotube is disclosed. The carbon nanotube is provided with a rotor plate attached to an outer wall, which moves relative to an inner wall of the nanotube. After deposit of a nanotube on a silicon chip substrate, the entire structure may be fabricated by lithography using selected techniques adapted from silicon manufacturing technology. The structures to be fabricated may comprise a multiwall carbon nanotube (MWNT), two in plane stators S1, S2 and a gate stator S3 buried beneath the substrate surface. The MWNT is suspended between two anchor pads and comprises a rotator attached to an outer wall and arranged to move in response to electromagnetic inputs. The substrate is etched away to allow the rotor to freely rotate. Rotation may be either in a reciprocal or fully rotatable manner.

Zettl, Alexander K. (Kensington, CA); Fennimore, Adam M. (Berkeley, CA); Yuzvinsky, Thomas D. (Berkeley, CA)

2008-11-18

411

DOI: 10.1002/adma.200700035 Quantum-Dot-Activated Luminescent Carbon Nanotubes via a  

E-print Network

DOI: 10.1002/adma.200700035 Quantum-Dot-Activated Luminescent Carbon Nanotubes via a Nano Scale conjugated carbon nanotubes has been realized in mice for the first time. The coupling of quantum dots on carbon nanotubes was materialized based on a novel plasma nanotube surface polymerization. The quan- tum

Papautsky, Ian

412

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

413

Optimizing the thermoelectric performance of zigzag and chiral carbon nanotubes  

PubMed Central

Using nonequilibrium molecular dynamics simulations and nonequilibrium Green's function method, we investigate the thermoelectric properties of a series of zigzag and chiral carbon nanotubes which exhibit interesting diameter and chirality dependence. Our calculated results indicate that these carbon nanotubes could have higher ZT values at appropriate carrier concentration and operating temperature. Moreover, their thermoelectric performance can be significantly enhanced via isotope substitution, isoelectronic impurities, and hydrogen adsorption. It is thus reasonable to expect that carbon nanotubes may be promising candidates for high-performance thermoelectric materials. PMID:22325623

2012-01-01

414

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

415

Carbon Nanotube Materials for Substrate Enhanced Control of Catalytic Activity  

SciTech Connect

Carbon SWNTs are attractive materials for supporting electrocatalysts. The properties of SWNTs are highly tunable and controlled by the nanotube's circumferential periodicity and their surface chemistry. These unique characteristics suggest that architectures constructed from these types of carbon support materials would exhibit interesting and useful properties. Here, we expect that the structure of the carbon nanotube support will play a major role in stabilizing metal electrocatalysts under extreme operating conditions and suppress both catalyst and support degradation. Furthermore, the chemical modification of the carbon nanotube surfaces can be expected to alter the interface between the catalyst and support, thus, enhancing the activity and utilization of the electrocatalysts. We plan to incorporate discrete reaction sites into the carbon nanotube lattice to create intimate electrical contacts with the catalyst particles to increase the metal catalyst activity and utilization. The work involves materials synthesis, design of electrode architectures on the nanoscale, control of the electronic, ionic, and mass fluxes, and use of advanced optical spectroscopy techniques.

Heben, M.; Dillon, A. C.; Engtrakul, C.; Lee, S.-H.; Kelley, R. D.; Kini, A. M.

2007-05-01

416

Integrating carbon nanotubes into silicon by means of vertical carbon nanotube field-effect transistors.  

PubMed

Single-walled carbon nanotubes have been integrated into silicon for use in vertical carbon nanotube field-effect transistors (CNTFETs). A unique feature of these devices is that a silicon substrate and a metal contact are used as the source and drain for the vertical transistors, respectively. These CNTFETs show very different characteristics from those fabricated with two metal contacts. Surprisingly, the transfer characteristics of the vertical CNTFETs can be either ambipolar or unipolar (p-type or n-type) depending on the sign of the drain voltage. Furthermore, the p-type/n-type character of the devices is defined by the doping type of the silicon substrate used in the fabrication process. A semiclassical model is used to simulate the performance of these CNTFETs by taking the conductance change of the Si contact under the gate voltage into consideration. The calculation results are consistent with the experimental observations. PMID:24965261

Li, Jingqi; Wang, Qingxiao; Yue, Weisheng; Guo, Zaibing; Li, Liang; Zhao, Chao; Wang, Xianbin; Abutaha, Anas I; Alshareef, H N; Zhang, Yafei; Zhang, X X

2014-08-01

417

Mechanical modelling of carbon nanomaterials from nanotubes to buckypaper  

Microsoft Academic Search

A combination of molecular structural mechanics and finite element method is used to mechanically model graphene, single-walled and multi-walled carbon nanotubes, nanotube bundles, buckypaper, and buckypaper composites. The mechanical model developed is used to determine the elastic properties of these nanostructures including elastic and shear moduli. In each step, different parameters are investigated including length and orientation of graphene sheets,

M. M. Zaeri; S. Ziaei-Rad; A. Vahedi; F. Karimzadeh

2010-01-01

418

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.

419

FEATURE ARTICLE Room Temperature Ballistic Conduction in Carbon Nanotubes  

E-print Network

nanotubes are shown to be ballistic conductors at room temperature, with mean free paths of the order that contact with a liquid metal surface. These experiments follow and extend the original experiments by Frank that the multiwalled carbon nanotubes (MWNTs) are one-dimensional conductors, that electronic transport occurs

Wang, Zhong L.

420

Cathode Ray Tube Lighting Elements with Carbon Nanotube Field Emitters  

Microsoft Academic Search

We have manufactured cathode ray tubes (CRTs) equipped with field emitters composed of multiwalled carbon nanotubes. The fabricated CRTs (20 mm in diameter by 74 mm in length) are of a triode type, consisting of a cathode (nanotube field emitter arrays), a grid and an anode (phosphor screen). The manufactured CRTs are lighting elements, which are assembled to form a

Yahachi Saito; Sashiro Uemura; Koji Hamaguchi

1998-01-01

421

Measurement of the Adhesion Force between Carbon Nanotubes and a  

E-print Network

mechanically robust composites and fibers.10,11 We used a suspended nanotube geometry to study nano- tube events, nano- tubes were pushed only far enough for slip to be detected. This allowed measurementsMeasurement of the Adhesion Force between Carbon Nanotubes and a Silicon Dioxide Substrate Jed D

McEuen, Paul L.

422

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 nanotubes (SWNTs) has been studied under CW illumination in the NIR (900 � 1800 nm) and far-IR (9-10 ����m state or continuous wave (CW) illumination presents interest not only for a fundamental understanding

Euler, William B.

423

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

424

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

425

Carbon Nanotube Assemblies for Transparent Conducting Electrodes  

SciTech Connect

The goal of this chapter is to introduce readers to the fundamental and practical aspects of nanotube assemblies made into transparent conducting networks and discuss some practical aspects of their characterization. Transparent conducting coatings (TCC) are an essential part of electro-optical devices, from photovoltaics and light emitting devices to electromagnetic shielding and electrochromic widows. The market for organic materials (including nanomaterials and polymers) based TCCs is expected to show a growth rate of 56.9% to reach nearly 20.3billionin2015,whilethemarketfortraditionalinorganictransparentelectronicswillexperiencegrowthwithratesof6.7103 billion in 2015. Emerging flexible electronic applications have brought additional requirements of flexibility and low cost for TCC. However, the price of indium (the major component in indium tin oxide TCC) continues to increase. On the other hand, the price of nanomaterials has continued to decrease due to development of high volume, quality production processes. Additional benefits come from the low cost, nonvacuum deposition of nanomaterials based TCC, compared to traditional coatings requiring energy intensive vacuum deposition. Among the materials actively researched as alternative TCC are nanoparticles, nanowires, and nanotubes with high aspect ratio as well as their composites. The figure of merit (FOM) can be used to compare TCCs made from dissimilar materials and with different transmittance and conductivity values. In the first part of this manuscript, we will discuss the seven FOM parameters that have been proposed, including one specifically intended for flexible applications. The approach for how to measure TCE electrical properties, including frequency dependence, will also be discussed. We will relate the macroscale electrical characteristics of TCCs to the nanoscale parameters of conducting networks. The fundamental aspects of nanomaterial assemblies in conducting networks will also be addressed. We will review recent literature on TCCs composed of carbon nanotubes of different types in terms of the FOM.

Garrett, Matthew P [ORNL] [ORNL; Gerhardt, Rosario [ORNL] [ORNL

2012-01-01

426

Helical polycarbodiimide cloaking of carbon nanotubes enables inter-nanotube exciton energy transfer modulation.  

PubMed

The use of single-walled carbon nanotubes (SWCNTs) as near-infrared optical probes and sensors require the ability to simultaneously modulate nanotube fluorescence and functionally derivatize the nanotube surface using noncovalent methods. We synthesized a small library of polycarbodiimides to noncovalently encapsulate SWCNTs with a diverse set of functional coatings, enabling their suspension in aqueous solution. These polymers, known to adopt helical conformations, exhibited ordered surface coverage on the nanotubes and allowed systematic modulation of nanotube optical properties, producing up to 12-fold differences in photoluminescence efficiency. Polymer cloaking of the fluorescent nanotubes facilitated the first instance of controllable and reversible internanotube exciton energy transfer, allowing kinetic measurements of dynamic self-assembly and disassembly. PMID:25343218

Budhathoki-Uprety, Januka; Jena, Prakrit V; Roxbury, Daniel; Heller, Daniel A

2014-11-01

427

Encapsulation of organic molecules in carbon nanotubes: role of the van der Waals interactions  

NASA Astrophysics Data System (ADS)

Carbon nanotubes are fascinating nano-objects not only from a fundamental point of view but also with respect to their remarkable properties, holding great potential in new materials design. When combined with organic molecules, these properties can be enhanced or modulated in order to fulfil the demand in domains as diverse as molecular electronics, biomaterials or even construction engineering, to name a few. To adequately conceive these hybrid materials it is essential to fully appreciate the nature of molecule-carbon nanotube interactions. In this review, we will discuss some relevant fundamental and applied research done on encapsulated molecules in carbon nanotubes. We will particularly focus on the weak and van der Waals interactions which rule the molecule-tube coupling. Therefore a small state of the art on the theoretical methods used to describe these interactions is presented here. Then, we will discuss various applications of molecular encapsulation, where we will consider structural, magnetic, charge transfer and transport, and optical properties.

Dappe, Y. J.

2014-02-01

428

Microstructure and wear property of carbon nanotube carburizing carbon steel by laser surface remelting  

Microsoft Academic Search

Carbon nanotube was used to carburize the surface of medium carbon steel and mild steel, respectively, by means of laser surface remelting. The slurry of carbon nanotube of ethanol was coated on the surface of the materials prior to laser irradiation. Microstructures, microhardness and wear property of the surface layers treated by different laser performance parameters were studied. Graphite coating

Jianhua Yao; Qunli Zhang; Mingxia Gao; Wei Zhang

2008-01-01

429

Flame Synthesis Used to Create Metal-Catalyzed Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

Metal-catalyzed carbon nanotubes are highly ordered carbon structures of nanoscale dimensions. They may be thought of as hollow cylinders whose walls are formed by single atomic layers of graphite. Such cylinders may be composed of many nested, concentric atomic layers of carbon or only a single layer, the latter forming a single-walled carbon nanotube. This article reports unique results using a flame for their synthesis. Only recently were carbon nanotubes discovered within an arc discharge and recognized as fullerene derivatives. Today metal-catalyzed carbon nanotubes are of great interest for many reasons. They can be used as supports for the metal catalysts like those found in catalytic converters. Open-ended nanotubes are highly desirable because they can be filled by other elements, metals or gases, for battery and fuel cell applications. Because of their highly crystalline structure, they are significantly stronger than the commercial carbon fibers that are currently available (10 times as strong as steel but possessing one-sixth of the weight). This property makes them highly desirable for strengthening polymer and ceramic composite materials. Current methods of synthesizing carbon nanotubes include thermal pyrolysis of organometallics, laser ablation of metal targets within hydrocarbon atmospheres at high temperatures, and arc discharges. Each of these methods is costly, and it is unclear if they can be scaled for the commercial synthesis of carbon nanotubes. In contrast, flame synthesis is an economical means of bulk synthesis of a variety of aerosol materials such as carbon black. Flame synthesis of carbon nanotubes could potentially realize an economy of scale that would enable their use in common structural materials such as car-body panels. The top figure is a transmission electron micrograph of a multiwalled carbon nanotube. The image shows a cross section of the atomic structure of the nanotube. The dark lines are individual atomic layer planes of carbon, seen here in cross section. They form a nested series of concentric cylinders, much like the growth rings on a tree. This sample was obtained by the supported catalyst method, whereby the nanoscale catalysts are dispersed on a substrate providing their support. The substrate with catalyst particles was immersed within an acetylene diffusion flame to which nitrogen had been added to eliminate soot formation. Upon removal from the flame, the nanotubes were dispersed on a holder suitable for electron microscopy. Although not seen in the figure, the tube diameter reflects that of the catalyst particle.

VanderWal, Randy L.

2001-01-01

430

Recent progress in carbon nanotube-based flexible transparent conducting film  

Microsoft Academic Search

Flexible transparent conducting films (TCFs) were fabricated on a PET substrate by various methods using carbon nanotubes dispersed in organic or water-based solution. Thin multi-walled carbon nanotubes, double-walled carbon nanotubes, and single-walled carbon nanotubes were used to compare the performance for TCFs. Optimal design rules for types of nanotubes, surfactants, the degree of dispersion, and film preparation methods were discussed.

Hong-Zhang Geng; Ki Kang Kim; Young Hee Lee

2008-01-01

431

Improvement of thermal contact resistance by carbon nanotubes and nanofibers  

NASA Technical Reports Server (NTRS)

Interfacial thermal resistance results of various nanotube and nanofiber coatings, prepared by chemical vapor deposition (CVD) methods, are reported at relatively low clamping pressures. The five types of samples examined include multi-walled and single-walled nanotubes growth by CVD, multi-walled nanotubes grown by plasma enhanced CVD (PECVD) and carbon nanofibers of differing aspect ratio grown by PECVD. Of the samples examined, only high aspect ratio nanofibers and thermally grown multi-walled nanotubes show an improvement in thermal contact resistance. The improvement is approximately a 60% lower thermal resistance than a bare Si-Cu interface and is comparable to that attained by commercially available thermal interface materials.

Chuang, Helen F.; Cooper, Sarah M.; Meyyappan, M.; Cruden, Brett A.

2004-01-01

432

Engineered Carbon Nanotube Materials for High-Q Nanomechanical Resonators  

NASA Technical Reports Server (NTRS)

This document represents a presentation offered by the Jet Propulsion Laboratory, with assistance from researchers from Brown University and Northrop Grumman. The presentation took place in Seoul, Korea in July 2003 and attempted to demonstrate the fabrication approach regarding the development of high quality factor (high-Q) mechanical oscillators (in the forms of a tunable nanotube resonator and a nanotube array radio frequency [RF] filter) aimed at signal processing and based on carbon nanotubes. The presentation also addressed parallel efforts to develop both in-plane single nanotube resonators as well as vertical array power devices.

Choi, Daniel S.; Hunt, Brian; Bronikowski, Mike; Epp, Larry; Hoenk, Michael; Hoppe, Dan; Kowalczyk, Bob; Wong, Eric; Xu, Jimmy; Adam, Douglas; Young, Rob

2003-01-01

433

Process for separating metallic from semiconducting single-walled carbon nanotubes  

NASA Technical Reports Server (NTRS)

A method for separating semiconducting single-walled carbon nanotubes from metallic single-walled carbon nanotubes is disclosed. The method utilizes separation agents that preferentially associate with semiconducting nanotubes due to the electrical nature of the nanotubes. The separation agents are those that have a planar orientation, .pi.-electrons available for association with the surface of the nanotubes, and also include a soluble portion of the molecule. Following preferential association of the separation agent with the semiconducting nanotubes, the agent/nanotubes complex is soluble and can be solubilized with the solution enriched in semiconducting nanotubes while the residual solid is enriched in metallic nanotubes.

Sun, Ya-Ping (Inventor)

2008-01-01

434

Engineering carbon nanostructures : development of novel aerogel-nanotube composites and optimization techniques for nanotube growth  

E-print Network

Carbon aerogels offer several unique advantages which make them ideal for evaluating a metal's ability to catalyze nanotube growth, including in situ carbothermic reduction of oxidized nanoparticles to their catalytic ...

Steiner, Stephen Alan, III

2006-01-01

435

Fully Integrated Graphene and Carbon Nanotube Interconnects for Gigahertz High-Speed Cmos Electronics  

E-print Network

Carbon-based nanomaterials such as metallic single-walled carbon nanotubes, multiwalled carbon nanotubes (MWCNTs), and graphene have been considered as some of the most promising candidates for future interconnect technology ...

Chen, Xiangyu

436

Patterned Growth of Carbon Nanotubes or Nanofibers  

NASA Technical Reports Server (NTRS)

A method and apparatus for the growth of carbon nanotubes or nanofibers in a desired pattern has been invented. The essence of the method is to grow the nanotubes or nanofibers by chemical vapor deposition (CVD) onto a patterned catalyst supported by a substrate. The figure schematically depicts salient aspects of the method and apparatus in a typical application. A substrate is placed in a chamber that contains both ion-beam sputtering and CVD equipment. The substrate can be made of any of a variety of materials that include several forms of silicon or carbon, and selected polymers, metals, ceramics, and even some natural minerals and similar materials. Optionally, the substrate is first coated with a noncatalytic metal layer (which could be a single layer or could comprise multiple different sublayers) by ion-beam sputtering. The choice of metal(s) and thickness(es) of the first layer (if any) and its sublayers (if any) depends on the chemical and electrical properties required for subsequent deposition of the catalyst and the subsequent CVD of the carbon nanotubes. A typical first-sublayer metal is Pt, Pd, Cr, Mo, Ti, W, or an alloy of two or more of these elements. A typical metal for the second sublayer or for an undivided first layer is Al at a thickness .1 nm or Ir at a thickness .5 nm. Proper choice of the metal for a second sublayer of a first layer makes it possible to use a catalyst that is chemically incompatible with the substrate. In the next step, a mask having holes in the desired pattern is placed over the coated substrate. The catalyst is then deposited on the coated substrate by ion-beam sputtering through the mask. Optionally, the catalyst could be deposited by a technique other than sputtering and/or patterned by use of photolithography, electron- beam lithography, or another suitable technique. The catalytic metal can be Fe, Co, Ni, or an alloy of two or more of these elements, deposited to a typical thickness in the range from 0.1 to 20 nm.

Delzeit, Lance D.

2004-01-01

437

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

438

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

439

Production and Characterization of Carbon Nanotubes and Nanotube-Based Composites  

NASA Technical Reports Server (NTRS)

The Nobel Prize winning discovery of the Buckuball (C60) in 1985 at Rice University by a group including Dr. Richard Smalley led to the whole new class of carbon allotropes including fullerenes and nanotubes. Especially interesting from many viewpoints are single-walled carbon nanotubes, which structurally are like a single graphitic sheet wrapped around a cylinder and capped at the ends. This cylinders have diameter as small as 0.5 - 2 nm (1/100,000th the diameter of a human hair) and are as long as 0.1 - 1 mm. Nanotubes are really individual molecules and believed to be defect-free, leading to high tensile strength despite their low density. Additionally, these fibers exhibit electrical conductivity as high as copper, thermal conductivity as high as diamond, strength 100 times higher than steel at one-sixth the weight, and high strain to failure. Thus it is believed that developments in the field of nanotechnology will lead to stronger and lighter composite materials for next generation spacecraft. Lack of a bulk method of production is the primary reason nanotubes are not used widely today. Toward this goal JSC nanotube team is exploring three distinct production techniques: laser ablation, arc discharge and chemical vapor deposition (CVD, in collaboration with Rice University). In laser ablation technique high-power laser impinges on the piece of carbon containing small amount of catalyst, and nanotubes self-assemble from the resulting carbon vapor. In arc generator similar vapor is created in arc discharge between carbon electrodes with catalyst. In CVD method nanotubes grow at much lower temperature on small catalyst particles from carbon-containing feedstock gas (methane or carbon monoxide). As of now, laser ablation produces cleanest material, but mass yield is rather small. Arc discharge produces grams of material, but purity is low. CVD technique is still in baby steps, but preliminary results look promising, as well as perspective of scaling the process up. We are also working on necessary purification of nanotubes. Applications of nanotubes are in such various fields as lightweight composites, molecular electronics, energy storage (electrodes in Li ion batteries), flat panel displays, conductive polymers, etc. JSC nanotube team is focused on development of lightweight materials. We work on the injection thermoset epoxies reinforced with nanotubes. Early results show good wetting of nanotube surface with epoxy, which is very important. More research will be possible as more nanotubes become available.

Nikolaev, Pavel; Arepalli, Sivaram; Holmes, William; Gorelik, Olga; Files, Brad; Scott, Carl; Santos, Beatrice; Mayeaux, Brian; Victor, Joe

1999-01-01

440

Hetero-doped Nanotubes: Theory, Synthesis and Characterization of Phosphorus-Nitrogen Doped Multiwalled Carbon Nanotubes  

SciTech Connect

Arrays of multiwalled carbon nanotubes doped with phosphorous and nitrogen are synthesized using a solution of ferrocene and triphenyl-phosphine in benzylamine in conjunction with spray pyrolysis. We demonstrate that iron phosphide (Fe3P) nanoparticles act as catalysts during nanotube growth, leading to the formation of novel PN-doped multiwalled carbon nanotubes. The samples produced were examined by SEM, HRTEM and STEM, as well as high-resolution elemental analyses using EELS and EDX spectroscopy, and their chemical stability was explored by means of thermogravimetric analysis in the presence of oxygen. The results reveal striking differences when compared to other types of doped nanotubes. These types of hetero-doped nanotubes with the underlying theory and synthesis are predicted to offer great opportunities in the fabrication of fast responsive chemical sensors.

Sumpter, Bobby G [ORNL; Cruz Silva, Eduardo [ORNL; Romo Herrera, Jose M [ORNL; Smith, David J [Arizona State University; Terrones Maldonado, Humberto [ORNL; Terrones Maldonado, Mauricio [ORNL; Meunier, Vincent [ORNL; Cullen, David A [Arizona State University; Charlier, Jean Christophe [Universite Catholique de Louvain; Lopez, Florentino [IPICyT; Gu, Lin [IPICyT; Munoz-Sandoval, Emilio [IPICyT

2008-01-01

441

Cross-polarized excitons in carbon nanotubes  

PubMed Central

Polarization of low-lying excitonic bands in finite-size semiconducting single-walled carbon nanotubes (SWNTs) is studied by using quantum-chemical methodologies. Our calculations elucidate properties of cross-polarized excitons, which lead to the transverse optical absorption of nanotubes and presumably couple to intermediate-frequency modes recently observed in resonance Raman excitation spectroscopy. We identify up to 12 distinct excitonic transitions below the second fundamental band associated with the E22 van Hove singularity. Calculations for several chiral SWNTs distinguish the optically active “bright” excitonic band polarized parallel to the tube axis and several optically “weak” cross-polarized excitons. The rest are optically (near) forbidden “dark” transitions. An analysis of the transition density matrices related to excitonic bands provides detailed information about delocalization of excitonic wavefunction along the tube. Utilization of the natural helical coordinate system accounting for the tube chirality allows one to disentangle longitudinal and circumferential components. The distribution of the transition density matrix along a tube axis is similar for all excitons. However, four parallel-polarized excitons associated with the E11 transition are more localized along the circumference of a tube, compared with others related to the E12 and E21 cross-polarized transitions. Calculated splitting between optically active parallel- and cross-polarized transitions increases with tube diameter, which compares well with experimental spectroscopic data. PMID:18463293

Kilina, Svetlana; Tretiak, Sergei; Doorn, Stephen K.; Luo, Zhengtang; Papadimitrakopoulos, Fotios; Piryatinski, Andrei; Saxena, Avadh; Bishop, Alan R.

2008-01-01

442

Universal nonresonant absorption in carbon nanotubes  

NASA Astrophysics Data System (ADS)

Photoluminescence excitation measurements in semiconducting carbon nanotubes show a systematic nonresonant contribution between the well-known excitonic resonances. Using a global analysis method, we were able to delineate the contribution of each chiral species, including its tiny nonresonant component. By comparison with the recently reported excitonic absorption cross section on the S22 resonance, we found a universal nonresonant absorbance which turns out to be of the order of one-half of that of an equivalent graphene sheet. This value, as well as the absorption line shape in the nonresonant window, is in excellent agreement with microscopic calculations based on the density-matrix formalism. This nonresonant absorption of semiconducting nanotubes is essentially frequency independent over 0.5-eV-wide windows and reaches approximately the same value between the S11 and S22 resonances and between the S22 and S33 resonances. In addition, the nonresonant absorption cross section turns out to be the same for all the chiral species we measured in this study. From a practical point of view, this study provides a solid framework for sample content analysis based on photoluminescence studies by targeting specific excitation wavelengths that lead to almost uniform excitation of all the chiral species of a sample within a given diameter range.

Vialla, Fabien; Malic, Ermin; Langlois, Benjamin; Chassagneux, Yannick; Diederichs, Carole; Deleporte, Emmanuelle; Roussignol, Philippe; Lauret, Jean-Sébastien; Voisin, Christophe

2014-10-01

443

Tailored Carbon Nanotubes for Tissue Engineering Applications  

PubMed Central

A decade of aggressive researches on carbon nanotubes (CNTs) has paved way for extending these unique nanomaterials into a wide range of applications. In the relatively new arena of nanobiotechnology, a vast majority of applications are based on CNTs, ranging from miniaturized biosensors to organ regeneration. Nevertheless, the complexity of biological systems poses a significant challenge in developing CNT-based tissue engineering applications. This review focuses on the recent developments of CNT-based tissue engineering, where the interaction between living cells/tissues and the nanotubes have been transformed into a variety of novel techniques. This integration has already resulted in a revaluation of tissue engineering and organ regeneration techniques. Some of the new treatments that were not possible previously become reachable now. Because of the advent of surface chemistry, the CNT’s biocompatibility has been significantly improved, making it possible to serve as tissue scaffolding materials to enhance the organ regeneration. The superior mechanic strength and chemical inert also makes it ideal for blood compatible applications, especially for cardiopulmonary bypass surgery. The applications of CNTs in these cardiovascular surgeries led to a remarkable improvement in mechanical strength of implanted catheters and reduced thrombogenecity after surgery. Moreover, the functionalized CNTs have been extensively explored for in vivo targeted drug or gene delivery, which could potentially improve the efficiency of many cancer treatments. However, just like other nanomaterials, the cytotoxicity of CNTs has not been well established. Hence, more extensive cytotoxic studies are warranted while converting the hydrophobic CNTs into biocompatible nanomaterials. PMID:19496152

Veetil, Jithesh V.; Ye, Kaiming

2008-01-01

444

Metal Nanoparticle Catalysts for Carbon Nanotube Growth  

NASA Technical Reports Server (NTRS)

Work this summer involved and new and unique process for producing the metal nanoparticle catalysts needed for carbon nanotube (CNT) growth. There are many applications attributed to CNT's, and their properties have deemed them to be a hot spot in research today. Many groups have demonstrated the versatility in CNT's by exploring a wide spectrum of roles that these nanotubes are able to fill. A short list of such promising applications are: nanoscaled electronic circuitry, storage media, chemical sensors, microscope enhancement, and coating reinforcement. Different methods have been used to grow these CNT's. Some examples are laser ablation, flame synthesis, or furnace synthesis. Every single approach requires the presence of a metal catalyst (Fe, Co, and Ni are among the best) that is small enough to produce a CNT. Herein lies the uniqueness of this work. Microemulsions (containing inverse micelles) were used to generate these metal particles for subsequent CNT growth. The goal of this summer work was basically to accomplish as much preliminary work as possible. I strived to pinpoint which variable (experimental process, metal product, substrate, method of application, CVD conditions, etc.) was the determining factor in the results. The resulting SEM images were sufficient for the appropriate comparisons to be made. The future work of this project consists of the optimization of the more promising experimental procedures and further exploration onto what exactly dictated the results.

Pierce, Benjamin F.

2003-01-01

445

Carbon nanotube based NEMS actuators and sensors  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs) have been widely studied due to superior mechanical and electrical properties. We have grown vertically aligned SWNTs (VA-SWNTs) onto microcantilever (MC) arrays, which provides an architecture for novel actuators and sensors. Raman spectroscopy confirms that the CVD-grown nanotubes are SWNTs and SEM confirms aligned growth. As an actuator, this hybrid MC/VA-SWNT system can be electrostatically modulated. SWNTs are excellent electron acceptors, so we can charge up the VA-SWNT array by applying a voltage. The electrostatic repulsion among the charged SWNTs provides a surface stress that induces MC deflection. Simulation results show that a few electrons per SWNT are needed for measureable deflections, and experimental actuators are being characterized by SEM, Raman, and an AFM optical lever system. The applied voltage is sinusoidally modulated, and deflection is measured with a lock-in amplifier. These actuators could be used for nano-manipulation, release of drugs from a capsule, or nano-valves. As a sensor, this MC/VA-SWNT system offers an improved sensitivity for chemical and bio-sensing compared to surface functionalized MC-based sensors. Those sensors only have a 2D sensing surface, but a MC/VA-SWNT system has significantly more sensing surface because the VA-SWNTs extend microns off the MC surface.

Forney, Michael; Poler, Jordan

2011-03-01

446

Individual single-walled carbon nanotubes as electrochemical probes  

NASA Astrophysics Data System (ADS)

We have performed cyclic voltammetry measurements using individual single-walled carbon nanotubes as working electrodes. The nanotubes were first grown on silicon oxide substrates and contacted using titanium. An insulating layer was then deposited and sub-micron-sized windows opened, leaving only the sidewalls of selected nanotubes exposed. These devices were exposed to an electrolyte containing redox-active ferrocene derivatives and cyclic voltammetry measurements were performed. Our results suggest that metallic nanotubes behave as ideal cylindrical electrodes and exhibit a diffusion-limited redox current. The behavior of semiconducting nanotubes is more complex due to the interplay between band bending, quantum capacitance and the potential drop at the liquid-nanotube interface.

Lemay, S. G.; Heering, H. A.; Heller, I.; Kong, J.; Williams, K. A.; Dekker, C.

2004-03-01

447

Oxidative biodegradation of single- and multi-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

In this study we compare the biodegradation of both single-walled (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) using two different oxidative conditions. In particular, we demonstrate that oxidized multi-walled carbon nanotubes are highly degraded, although not to completeness when treated with horseradish peroxidase (HRP) in the presence of hydrogen peroxide.In this study we compare the biodegradation of both single-walled (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) using two different oxidative conditions. In