Sample records for carbon nanotube magnet

  1. Anisotropic magnetic susceptibility of multiwalled carbon nanotubes

    Microsoft Academic Search

    F. Tsui; L. Jin; O. Zhou

    2000-01-01

    Magnetic susceptibility of partially aligned multiwalled carbon nanotubes has been studied using superconducting quantum interference device magnetometry. Partial alignment of multiwalled nanotubes was produced by uniaxially straining composites of carbon nanotubes embedded in polymer matrices. The degree of alignment was determined by x-ray diffraction. The observed magnetic response is diamagnetic and anisotropic with the component along the nanotubes less diamagnetic

  2. Carbon nanotubes in confined magneticCarbon nanotubes in confined magnetic fields: thefields: the

    E-print Network

    Marini, Andrea

    as a change in the interference pattern #12;The AB effect in carbon nano-tubes A. Bachtold et al., Nature 397Zone-FoldingApproach J.C. Charlier et al, Rev. Mod. Phys. 79, 677 (2007) #12;The AB effect in carbon nano-tubes (CNTsCarbon nanotubes in confined magneticCarbon nanotubes in confined magnetic fields: thefields

  3. Flightweight Carbon Nanotube Magnet Technology

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

  4. Carbon nanotube based magnetic tunnel junctions

    PubMed

    Mehrez; Taylor; Guo; Wang; Roland

    2000-03-20

    Spin-coherent quantum transport in carbon nanotube magnetic tunnel junctions is investigated theoretically. A spin-valve effect is found for metallic, armchair tubes, with a magnetoconductance ratio ranging up to 20%. Because of the finite length of the nanotube junctions, transport is dominated by resonant transmission. The magnetic tunnel junctions are found to have distinctly different transport behavior depending on whether or not the length of the tubes is commensurate with a 3N+1 rule, with N the number of basic carbon repeat units along the nanotube length. PMID:11017299

  5. Carbon nanotubes in confined magnetic fields: gap oscillations and

    E-print Network

    Marini, Andrea

    as a change in the interference pattern #12;The AB effect in carbon nano-tubes (CNTs) (I) A. Bachtold et al in carbon nano-tubes (CNTs) (II) #12;CNTs in a uniform B field: The Lorentz correction RCNT S. Zaric et alCarbon nanotubes in confined magnetic fields: gap oscillations and persistent currents from a new

  6. Magnetic Properties of Carbon Nanotubes with Low Content of Fe

    Microsoft Academic Search

    V. S. Zagainova; T. L. Makarova; A. V. Okotrub; A. G. Kurenya; S. V. Komogortsev; L. G. Bulusheva

    2010-01-01

    Films of oriented carbon nanotubes containing different concentrations of ferrocene (0.5%, 1%, 1.5%, 2%, 2.5% and 5%) have been synthesized by CVD method and studied by means of SQUID and force microscopy. Strong dependence of magnetization process on nanotubes parameters is observed. Magnetic anisotropy of low-doped nanotubes is shown to have an easy magnetic axis perpendicular to the aligned nanotubes.

  7. Magnetically Active Carbon Nanotubes at Work.

    PubMed

    Stopin, Antoine; Pineux, Florent; Marega, Riccardo; Bonifazi, Davide

    2015-06-22

    Endohedral and exohedral assembly of magnetic nanoparticles (MNPs) and carbon nanotubes (CNTs) recently gave birth to a large body of new hybrid nanomaterials (MNPs-CNTs) featuring properties that are otherwise not in reach with only the graphitic or metallic cores themselves. These materials feature enhanced magnetically guided motions (rotation and translation), magnetic saturation and coercivity, large surface area, and thermal stability. By guiding the reader through the most significant examples in this Concept paper, we describe how researchers in the field engineered and exploited the synergistic combination of these two types of nanoparticles in a large variety of current and potential applications, such as magnetic fluid hyperthermia therapeutics and in magnetic resonance imaging to name a few. PMID:26017389

  8. Carbon nanotubes in confined magneticCarbon nanotubes in confined magnetic fields: AharonovBohm oscillations andfields: AharonovBohm oscillations and

    E-print Network

    Marini, Andrea

    ;The AB effect in carbon nano-tubes (CNTs) A. Bachtold et al., Nature 397, 673 (1999) S. Zaric et alCarbon nanotubes in confined magneticCarbon nanotubes in confined magnetic fields: Aharonov;OutlineOutline Aharonov-Bohm oscillations in Carbon nanotubes Curvature effects Persistent currents #12

  9. Magnetic properties of aligned Fe-filled carbon nanotubes

    Microsoft Academic Search

    T. Mühl; D. Elefant; A. Graff; R. Kozhuharova; A. Leonhardt; I. Mönch; M. Ritschel; P. Simon; S. Groudeva-Zotova; C. M. Schneider

    2003-01-01

    We report on the magnetic properties of Fe-filled multiwalled carbon nanotubes (MWNTs) grown by chemical vapor deposition (CVD) on Si substrates with ferrocene as precursor. The MWNTs are aligned perpendicularly to the substrate plane. X-ray diffraction analyses indicate the presence of both bcc and fcc iron with a relatively strong texture. Magnetometry measurements show a pronounced magnetic anisotropy with the

  10. Temperature and Magnetic Field Dependent Photoluminescence from Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Nicholas, R. J.; Mortimer, I. B.; Li, L. J.; Nish, A.; Portugall, O.; Rikken, G. L. J. A.

    Photoluminescence as a function of temperature and magnetic field from single walled carbon nanotube solutions is described. This is modelled assuming that it is dominated by the small energy splitting between the dark and bright states of the singlet excitons which are found to be in the region of 1-5 meV for nanotubes of 0.8-1.2nm. The emission energies show a large red-shift due to the introduction of an Aharanov-Bohm phase by magnetic field along the tube axis and the luminescence intensity is strongly enhanced at low temperatures due to the mixing of the different valley states of the excitons.

  11. Carbon nanotubes and magnetic nanomaterials as substratum for neuroscience applications

    NASA Astrophysics Data System (ADS)

    Aatre, Kiran R.

    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.

  12. Magnetorheological properties of a magnetic nanofluid with dispersed carbon nanotubes.

    PubMed

    Felicia, Leona J; Philip, John

    2014-02-01

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

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

    E-print Network

    Garmestani, Hamid

    involving the anisotropic magnetic susceptibility of both the CNT and polymer systems. The anisotropyEnhancement of thermal and electrical properties of carbon nanotube polymer composites by magnetic. The alignment of CNTs in magnetic fields arises from the anisotropic magnetic susceptibility of nanotubes.7

  14. Magnetic nanotubes

    SciTech Connect

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

    2010-11-16

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

  15. High precision fluidic alignment of carbon nanotubes using magnetic attraction on a metal catalyst

    Microsoft Academic Search

    Joon S. Shim; Yeo-Heung Yun; Michael J. Rust; V. Shanov; M. J. Schulz; C. H. Ahn

    2008-01-01

    Precise self-assembly of carbon nanotubes (CNTs) by magnetic attraction on a catalyst and alignment by fluidic shear forces is reported in this work. The solution containing dispersed nanotubes was flowed in a microchannel and external magnetic field was applied by a permanent magnet for attracting a metal catalyst located at the end of the CNT. The assembly procedure and electrical

  16. Single Molecule Magnetic Force Detection with a Carbon Nanotube Resonator

    NASA Astrophysics Data System (ADS)

    Willick, Kyle; Walker, Sean; Baugh, Jonathan

    2015-03-01

    Single molecule magnets (SMMs) sit at the boundary between macroscopic magnetic behaviour and quantum phenomena. Detecting the magnetic moment of an individual SMM would allow exploration of this boundary, and could enable technological applications based on SMMs such as quantum information processing. Detection of these magnetic moments remains an experimental challenge, particularly at the time scales of relaxation and decoherence. We present a technique for sensitive magnetic force detection that should permit such measurements. A suspended carbon nanotube (CNT) mechanical resonator is combined with a magnetic field gradient generated by a ferromagnetic gate electrode, which couples the magnetic moment of a nanomagnet to the resonant motion of the CNT. Numerical calculations of the mechanical resonance show that resonant frequency shifts on the order of a few kHz arise due to single Bohr magneton changes in magnetic moment. A signal-to-noise analysis based on thermomechanical noise shows that magnetic switching at the level of a Bohr magneton can be measured in a single shot on timescales as short as 10 ?s. This sensitivity should enable studies of the spin dynamics of an isolated SMM, within the spin relaxation timescales for many available SMMs. Supported by NSERC.

  17. Exciton splitting in semiconducting carbon nanotubes in ultrahigh magnetic fields above 300 T

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    In high magnetic fields, the exciton absorption spectrum of a semiconducting single-walled carbon nanotube splits as a result of Aharonov-Bohm magnetic flux. A magnetic field of 370 T, generated by the electromagnetic flux compression destructive pulsed magnet-coil technique, was applied to single-chirality semiconducting carbon nanotubes. Using streak spectroscopy, we demonstrated the separation of the independent band-edge exciton states at the K and K' points of the Brillouin zone after the mixing of the dark and bright states above 150 T. These results enable a quantitative discussion of the whole picture of the Aharonov-Bohm effect in single-walled carbon nanotubes.

  18. Magnetic Property Measurements on Single Wall Carbon Nanotube-Polyimide Composites

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  19. Tailored mechanical behavior of magnetic particles loaded carbon nanotube foam in presence of magnetic field

    NASA Astrophysics Data System (ADS)

    Reddy, Siva K.; Misra, Abha

    2015-07-01

    The compressive behavior of carbon nanotube (CNT) foam with an entangled microstructure has become an important research area due to its excellent energy absorption capability. This report presents a tailored mechanical behavior of CNT foam under an applied magnetic field when all CNTs in the foam are coated with magnetic nanoparticles. The presence of nanoparticles not only enhanced the stiffness of the foam to four times but also revealed a nonlinear variation in both the stress and energy absorption capability with the gradual increase of the magnetic field. Magnetization of both CNT and attached nanoparticles along the magnetic field direction are shown to play a crucial role in determining the dominant deformation mechanism.

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

    Microsoft Academic Search

    E. S. Choi; J. S. Brooks; D. L. Eaton; M. S. Al-Haik; M. Y. Hussaini; H. Garmestani; D. Li; K. Dahmen

    2003-01-01

    We show that the thermal and electrical properties of single wall carbon nanotube (CNT)-polymer composites are significantly enhanced by magnetic alignment during processing. The electrical transport properties of the composites are mainly governed by the hopping conduction with localization lengths comparable to bundle diameters. The bundling of nanotubes during the composite processing is an important factor for electrical, and in

  1. Effects of high magnetic field on the morphology of carbon nanotubes and selective synthesis of fullerenes

    Microsoft Academic Search

    Haruo Yokomichi; Hiroyuki Sakima; Masaki Ichihara; Fumiko Sakai; Kikuo Itoh; Naoki Kishimoto

    1999-01-01

    Carbon nanotubes and fullerenes were synthesized by arc discharge in a He gas atmosphere under a high magnetic field up to 10 T. Morphology and the yield of these nanotubes were investigated by scanning electron microscopy and transmission electron microscopy (TEM). The yield and type of fullerenes were also evaluated by ultraviolet visual spectroscopy. TEM images revealed that thin collapsed

  2. Indirect magnetic coupling in light-element-doped single-walled carbon nanotubes.

    PubMed

    Krsti?, Vojislav; Ewels, Christopher P; Wågberg, Thomas; Ferreira, Mauro S; Janssens, Anne M; Stéphan, Odile; Glerup, Marianne

    2010-09-28

    Single-walled carbon nanotubes substitutionally doped with the light-element phosphorus are synthesized and are investigated by electrical and nuclear magnetic resonance measurements. Decreased spin-lattice relaxation times compared to undoped tubes point toward enhanced spin-sensitive scattering. Temperature dependence of the zero-bias conductance shows step-like features, a signature of scattering from a very low density (few sites per nanotube) of localized spin moments at oxidized phosphorus sites, consistent with density functional calculations. This supports recent predictions that localized magnetic moments must be indirectly magnetically coupled through the nanotube conduction electrons. PMID:20684527

  3. Magnetically processed carbon nanotube\\/epoxy nanocomposites: Morphology, thermal, and mechanical properties

    Microsoft Academic Search

    Mohamed Abdalla; Derrick Dean; Merlin Theodore; Jennifer Fielding; Elijah Nyairo; Gary Price

    2010-01-01

    The processing-structure–property relationships of multiwalled carbon nanotubes (MWNTs)\\/epoxy nanocomposites processed with a magnetic field have been studied. Samples were prepared by dispersing the nanotube in the epoxy and curing under an applied magnetic field. The nanocomposite morphology was characterized with Raman spectroscopy and wide angle X-ray scattering, and correlated with thermo-mechanical properties. The modulus parallel to the alignment direction, as

  4. Carbon nanotube synthesis using a magnetic fluid via thermal chemical vapor deposition

    Microsoft Academic Search

    Yu-Suk Cho; Gyu-Seok Choi; Sang-Young Hong; Dojin Kim

    2002-01-01

    A new approach to synthesizing carbon nanotubes (CNTs) using dispersed magnetic fluids, instead of conventional metallic catalyst nanoparticles of Ni, Co, or Fe, was proposed. A magnetic fluid of surfactant-coated magnetite nanoparticles has been successfully applied for CNT synthesis in chemical vapor deposition by a simple spin coating method. Using the method dense and aligned CNTs were successfully grown on

  5. Photophysics of carbon nanotubes

    E-print Network

    Samsonidze, Georgii G

    2007-01-01

    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 ...

  6. Silver intercalated carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Borowiak-Palen, E.; Ruemmeli, M. H.; Mendoza, E.; Henley, S. J.; Cox, D. C.; Poa, C. H. P.; Stolojan, V.; Gemming, T.; Pichler, T.; Silva, S. R. P.

    2005-09-01

    The intercalation of metals within carbon nanotube structures has extended the potential applications of these materials to possible quantum memory elements as well as high density magnetic storage media. In our study we use methodologies based on wet chemistry and solid state physical (excimer laser) processes to incorporate silver nanoparticles in single and multiwall carbon nanotubes. We show high resolution TEM as evidence for the formation of very long ( ˜ 100-150 nm) silver quantum wires within SWCNT, and their properties are probed using various analytical techniques. The variation of the silver intercalated nanotube percentage and yield are compared for the SW- and MW-CNTs, when using wet chemistry versus physical processes.

  7. Well-aligned Co-filled carbon nanotubes: preparation and magnetic properties

    Microsoft Academic Search

    Radinka Kozhuharova; Manfred Ritschel; Dieter Elefant; Andreas Graff; Albrecht Leonhardt; Ingolf Mönch; Thomas Mühl; Stefka Groudeva-Zotova; Claus M. Schneider

    2004-01-01

    Carpet-like flakes (area ? 9mm2; thickness < 50?m) of well-aligned Co-filled multi-walled carbon nanotubes were grown by decomposition of cobaltocene. The nanotubes have outer diameters of 50–90nm and a metal core of 15–30nm diameter. They are discontinuously filled with f.c.c.-Co nanowires of up to a few micrometers in length. Magnetometry studies show a weak uniaxial magnetic anisotropy with the easy

  8. Magnetic Alignment of the Fe3O4-COATED Carbon Nanotubes Hybrids in Epoxy Nanocomposites

    NASA Astrophysics Data System (ADS)

    Zheng, Ya-Ping; Chen, Wei; Wu, Fei; Zheng, Guo-Bin; Xu, Ya-Hong; Zhang, Tao

    2013-08-01

    Multi-walled carbon nanotubes (MWNTs), which were coated with magnetic Fe3O4 nanoparticles, were cured and aligned in epoxy resin under magnetic field. They were aligned end-to-up under 0.6 T magnetic field. When the Fe3O4-MWNTs hybrids content was 0.3%, the electric conductivity were 4.2 S/cm. Frequency and Fe3O4-MWNTs hybrids content are the key roles for electric conductivity.

  9. Magnetic Brightening of Dark Excitons in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kono, Junichiro

    2007-03-01

    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).

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

    Microsoft Academic Search

    Ferenc Simon; Rudolf Pfeiffer; Hans Kuzmany

    2007-01-01

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

  11. The precise self-assembly of individual carbon nanotubes using magnetic capturing and fluidic alignment

    Microsoft Academic Search

    Joon S. Shim; Yeo-Heung Yun; Michael J. Rust; Vesselin Shanov; Mark J. Schulz; Chong H. Ahn

    2009-01-01

    A new method for the self-assembly of a carbon nanotube (CNT) using magnetic capturing and fluidic alignment has been developed and characterized in this work. In this new method, the residual iron (Fe) catalyst positioned at one end of the CNT was utilized as a self-assembly driver to attract and position the CNT, while the assembled CNT was aligned by

  12. Degeneracy in carbon nanotubes under transverse magnetic ?-fields.

    PubMed

    Kuru, ?; Negro, J; Tristao, S

    2015-07-22

    The aim of this article was to study the degeneracy of the energy spectrum in a nanotube under a transverse magnetic field. The massless Dirac-Weyl equation has been used to describe the low energy states of this system. The particular case of a singular magnetic field approximated by Dirac delta distributions is considered. It is shown that, under general symmetry conditions, there is a double degeneracy corresponding to periodic solutions with null axial momentum [Formula: see text]. Also, there may be a kind of sporadic degeneracy for non-vanishing values of [Formula: see text], which are explicitly computed in the present example. The proof of these properties is obtained by means of the supersymmetric structure of the Dirac-Weyl Hamiltonian. PMID:26102328

  13. Degeneracy in carbon nanotubes under transverse magnetic ?-fields

    NASA Astrophysics Data System (ADS)

    Kuru, ?.; Negro, J.; Tristao, S.

    2015-07-01

    The aim of this article was to study the degeneracy of the energy spectrum in a nanotube under a transverse magnetic field. The massless Dirac–Weyl equation has been used to describe the low energy states of this system. The particular case of a singular magnetic field approximated by Dirac delta distributions is considered. It is shown that, under general symmetry conditions, there is a double degeneracy corresponding to periodic solutions with null axial momentum {{k}z}=0 . Also, there may be a kind of sporadic degeneracy for non-vanishing values of {{k}z} , which are explicitly computed in the present example. The proof of these properties is obtained by means of the supersymmetric structure of the Dirac–Weyl Hamiltonian.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  15. Magnetic properties and transmission electron microscopy studies of Ni nanoparticles encapsulated in carbon nanocages and carbon nanotubes

    SciTech Connect

    He Chunnian [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Zhao Naiqin [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)], E-mail: nqzhao@tju.edu.cn; Shi Chunsheng; Li Jiajun; Li Haipeng [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)

    2008-08-04

    Three types of carbon nanomaterials, including bamboo-shaped carbon nanotubes with Ni encapsulated and hollow and Ni catalytic particles filled carbon nanocages, have been prepared by methane catalytic decomposition at a relatively low temperature. Transmission electron microscopy observations showed that fascinating fullerene-like Ni-C (graphitic) core-shell nanostructures predominated. Detailed examination of high-resolution transmission electron microscopy showed that the walls of bamboo-shaped carbon nanotubes with quasi-cone catalytic particles encapsulated consisted of oblique graphene planes with respect to the tube axis. The Ni particles encapsulated in the carbon nanocages were larger than that encapsulated in carbon nanotubes, but the diameters of the cores of hollow carbon nanocages were less than that of Ni particles encapsulated in carbon nanotubes, suggesting that the sizes of catalyst particles played an important role during carbon nanomaterial growth. The magnetic properties of the carbon nanomaterials were measured, which showed relatively large coercive force (H{sub c} = 138.4 O{sub e}) and good ferromagnetism (M{sub r}/M{sub s} = 0.325)

  16. Method for probing the magnetic state of nanomaterials encapsulated in carbon nanotubes

    Microsoft Academic Search

    Satoru Konabe; Susumu Okada

    2011-01-01

    We propose a method for optically probing the magnetic states of metallic atoms encapsulated in single-walled carbon nanotubes. The absorption spectrum is calculated by solving the Bethe-Salpeter equation, which includes the effects of magnetic atoms, under the tight-binding approximation. Due to the exchange interaction between excitons and polarized spins in ferromagnets, triplet excitons acquire a finite oscillator strength and can

  17. Preparation and characterization of magnetic multi-walled carbon nanotubes–poly( l-lactide) composite

    Microsoft Academic Search

    Jiangtao Feng; Jiehe Sui; Wei Cai; Jiaqi Wan; Ali Nabipour Chakoli; Zhiyong Gao

    2008-01-01

    The composites based on poly(l-lactide) (PLLA) and two kinds of multi-wall carbon nanotubes (Fe3O4\\/MWCNTs and MWCNTs) were prepared by solution casting. The molecular level interactions, thermal, magnetic, mechanical properties and dispersion of MWCNTs in polymer matrix were investigated by Raman spectroscopy, differential scanning calorimetry (DSC), magnetic property measure system (MPMS), tensile test and scanning electron microscopy (SEM). The results of

  18. Carbon Nanotube Image Gallery

    NSDL National Science Digital Library

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

  19. Preparation of Magnetic Carbon Nanotubes (Mag-CNTs) for Biomedical and Biotechnological Applications

    PubMed Central

    Masotti, Andrea; Caporali, Andrea

    2013-01-01

    Carbon nanotubes (CNTs) have been widely studied for their potential applications in many fields from nanotechnology to biomedicine. The preparation of magnetic CNTs (Mag-CNTs) opens new avenues in nanobiotechnology and biomedical applications as a consequence of their multiple properties embedded within the same moiety. Several preparation techniques have been developed during the last few years to obtain magnetic CNTs: grafting or filling nanotubes with magnetic ferrofluids or attachment of magnetic nanoparticles to CNTs or their polymeric coating. These strategies allow the generation of novel versatile systems that can be employed in many biotechnological or biomedical fields. Here, we review and discuss the most recent papers dealing with the preparation of magnetic CNTs and their application in biomedical and biotechnological fields. PMID:24351838

  20. Carbon nanotubes in almost homogeneous transverse magnetic field: exactly solvable model

    E-print Network

    Vit Jakubsky; Sengul Kuru; Javier Negro

    2014-01-22

    A class of exactly solvable models describing carbon nanotubes in the presence of an external inhomogeneous magnetic field is considered. The framework of the continuum approximation is employed, where the motion of the charge carriers is governed by the Dirac- Weyl equation. The explicit solution of a particular example is provided. It is shown that these models possess nontrivial integrals of motion that establish N = 2 nonlinear supersymmetry in case of metallic and maximally semiconducting nanotubes. Remarkable stability of energy levels with respect to small fluctuations of longitudinal momentum is demonstrated

  1. Carbon nanotubes in an inhomogeneous transverse magnetic field: exactly solvable model

    NASA Astrophysics Data System (ADS)

    Jakubský, V.; Kuru, ?.; Negro, J.

    2014-03-01

    A class of exactly solvable models describing carbon nanotubes in the presence of an external inhomogeneous magnetic field is considered. The framework of the continuum approximation is employed, where the motion of the charge carriers is governed by the Dirac-Weyl equation. The explicit solution of a particular example is provided. It is shown that these models possess nontrivial integrals of motion that establish N = 2 nonlinear supersymmetry in case of metallic and maximally semiconducting nanotubes. Remarkable stability of energy levels with respect to small fluctuations of longitudinal momentum is demonstrated.

  2. Growth and Nanoscale Magnetic Properties of Ferromagnetic Nanowire Encapsulated Inside Carbon Nanotubes

    Microsoft Academic Search

    Yasuhiko Hayashi; T. Fujita; T. Tokunaga; B. Jang; M. Tanemura; G. A. J. Amaratunga

    2009-01-01

    We synthesize ferromagnetic Co nanowire, and Co\\/Pd multisegment nanowires encapsulated inside multi-walled carbon nanotubes CNTs (MWCNTs) by plasma-enhanced chemical vapor deposition (PECVD). High-resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED) patterns and energy dispersive X-ray spectroscopy (EDS) were used to characterize the microstructures and elemental analyses of the nanowires. Quantitative magnetization measurements of Co nanowires encapsulated inside MWCNTs

  3. Carbon nanotube nanoelectrode arrays

    DOEpatents

    Ren, Zhifeng (Newton, MA); Lin, Yuehe (Richland, WA); Yantasee, Wassana (Richland, WA); Liu, Guodong (Fargo, ND); Lu, Fang (Burlingame, CA); Tu, Yi (Camarillo, CA)

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

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

    NASA Astrophysics Data System (ADS)

    Bagheri, Mehran; Abdikian, Alireza

    2014-04-01

    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.

  5. In vivo biodistribution and biological impact of injected carbon nanotubes using magnetic resonance techniques

    PubMed Central

    Al Faraj, Achraf; Fauvelle, Florence; Luciani, Nathalie; Lacroix, Ghislaine; Levy, Michael; Crémillieux, Yannick; Canet-Soulas, Emmanuelle

    2011-01-01

    Background: Single-walled carbon nanotubes (SWCNT) hold promise for applications as contrast agents and target delivery carriers in the field of nanomedicine. When administered in vivo, their biodistribution and pharmacological profile needs to be fully characterized. The tissue distribution of carbon nanotubes and their potential impact on metabolism depend on their shape, coating, and metallic impurities. Because standard radiolabeled or fluorescently-labeled pharmaceuticals are not well suited for long-term in vivo follow-up of carbon nanotubes, alternative methods are required. Methods: In this study, noninvasive in vivo magnetic resonance imaging (MRI) investigations combined with high-resolution magic angle spinning (HR-MAS), Raman spectroscopy, iron assays, and histological analysis ex vivo were proposed and applied to assess the biodistribution and biological impact of intravenously injected pristine (raw and purified) and functionalized SWCNT in a 2-week longitudinal study. Iron impurities allowed raw detection of SWCNT in vivo by susceptibility-weighted MRI. Results: A transitional accumulation in the spleen and liver was observed by MRI. Raman spectroscopy, iron assays, and histological findings confirmed the MRI readouts. Moreover, no acute toxicological effect on the liver metabolic profile was observed using the HR-MAS technique, as confirmed by quantitative real-time polymerase chain reaction analysis. Conclusion: This study illustrates the potential of noninvasive MRI protocols for longitudinal assessment of the biodistribution of SWCNT with associated intrinsic metal impurities. The same approach can be used for any other magnetically-labeled nanoparticles. PMID:21499425

  6. Uraemic Toxins Generated in the Presence of Fullerene C60, Carbon-Encapsulated Magnetic Nanoparticles, and Multiwalled Carbon Nanotubes

    PubMed Central

    Pop?awska, Magdalena

    2013-01-01

    Uraemic toxins—creatol and N-methylguanidine—are generated in conversion of creatinine in water in the presence of various forms of carbon such as fullerene C60, carbon-encapsulated magnetic nanoparticles, and multiwalled carbon nanotubes and oxygen. The conversion degree for creatinine was different for fullerene C60, CEMNPs, and MWCNTs and was 9% (3.6% creatol, 5.4% N-methylguanidine), 35% (12% creatol, 23% N-methylguanidine), and 75% (16% creatol, 59% N-methylguanidine), respectively. PMID:24078905

  7. Electron field emission from magnetic nanomaterial encapsulated multi-walled carbon nanotubes

    Microsoft Academic Search

    R. B. Rakhi; X. Lim; X. Gao; Y. Wang; A. T. S. Wee; K. Sethupathi; S. Ramaprabhu; C. H. Sow

    2010-01-01

    The present work describes the field emission characteristics of nanoscale magnetic nanomaterial encapsulated multi-walled\\u000a carbon nanotubes (MWNTs) fabricated over flexible graphitized carbon cloth. Ni\\/MWNTs, NiFe\\/MWNTs and NiFeCo\\/MWNTs have been\\u000a synthesized by catalytic chemical vapor decomposition of methane over Mischmetal (Mm)-based AB3 (MmNi3, MmFe1.5Ni1.5 and MmFeCoNi) alloy hydride catalysts. Metal-encapsulated MWNTs exhibited superior field emission performance than pure MWNT-based\\u000a field emitters

  8. Magnetically aligned carbon nanotube in nanopaper enabled shape-memory nanocomposite for high speed electrical actuation

    NASA Astrophysics Data System (ADS)

    Lu, Haibao; Gou, Jihua; Leng, Jinsong; Du, Shanyi

    2011-04-01

    A new shape-memory nanocomposite that exhibits rapid electrical actuation capabilities is fabricated by incorporating self-assembly multiwalled carbon nanotube (MWCNT) nanopaper and magnetic CNTs into a styrene-based shape-memory polymer (SMP). The MWCNT nanopaper was coated on the surface to give high electrical conductivity to SMP. Electromagnetic CNTs were blended with and, vertically aligned into the SMP resin upon a magnetic field, to facilitate the heat transfer from the nanopaper to the underlying SMP. This not only significantly enhances heat transfer but also gives high speed electrical actuation.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  10. Manipulating the magnetic state of a carbon nanotube Josephson junction using the superconducting phase

    NASA Astrophysics Data System (ADS)

    Delagrange, R.; Luitz, D. J.; Weil, R.; Kasumov, A.; Meden, V.; Bouchiat, H.; Deblock, R.

    2015-06-01

    The magnetic state of a quantum dot attached to superconducting leads is experimentally shown to be controlled by the superconducting phase difference across the dot. This is done by probing the relation between the Josephson current and the superconducting phase difference of a carbon nanotube junction whose Kondo energy and superconducting gap are of comparable size. It exhibits distinctively anharmonic behavior, revealing a phase-mediated singlet-to-doublet transition. We obtain an excellent quantitative agreement with numerically exact quantum Monte Carlo calculations. This provides strong support that we indeed observed the finite-temperature signatures of the phase-controlled zero temperature level crossing transition originating from strong local electronic correlations.

  11. Manipulating the magnetic state of a carbon nanotube Josephson junction using the superconducting phase

    E-print Network

    R. Delagrange; D. J. Luitz; R. Weil; A. Kasumov; V. Meden; H. Bouchiat; R. Deblock

    2015-06-10

    The magnetic state of a quantum dot attached to superconducting leads is experimentally shown to be controlled by the superconducting phase difference across the dot. This is done by probing the relation between the Josephson current and the superconducting phase difference of a carbon nanotube junction whose Kondo energy and superconducting gap are of comparable size. It exhibits distinctively anharmonic behavior, revealing a phase mediated singlet to doublet transition. We obtain an excellent quantitative agreement with numerically exact quantum Monte Carlo calculations. This provides strong support that we indeed observed the finite temperature signatures of the phase controlled zero temperature level-crossing transition originating from strong local electronic correlations.

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

    PubMed

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

    2013-04-01

    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 r 1 and r 2 relaxivities at very low (0.01?MHz) to clinically relevant (61?MHz) magnetic fields (r 1???130?mM(-1)?s(-1), r 2???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 [Formula: see text], rate of water exchange [Formula: see text], and the number of fast-exchanging water molecules within the inner sphere q may be responsible for the increase in r 1 and r 2 relaxivity. The T 1 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

  13. Magnetic poly(vinylpyridine)-coated carbon nanotubes: an efficient supramolecular tool for wastewater purification.

    PubMed

    Maggini, Laura; Raquez, Jean-Marie; Marega, Riccardo; Jensen Ahrens, Jennifer; Pineux, Florent; Meyer, Franck; Dubois, Philippe; Bonifazi, Davide

    2013-02-01

    Herein, we report the first example of a supramolecular carbon nanotube (CNT)-based magnetic depolluting agent for divalent metal ion (M(2+)) removal from aqueous solutions. In particular, magnetic multi-walled carbon nanotubes (m-MWCNTs) coated with poly(vinylpyridine) (PVPy) self-aggregate in aqueous solutions that contain divalent metal ions (such as Zn(2+), Cu(2+) and Pb(2+)) to form tight insoluble bundles in which the M(2+) ions remain trapped through pyridyl-M(2+)-pyridyl interactions. Magnetic filtration ultimately affords the efficient separation of the depolluted solution from the precipitated M(2+)-CNT agglomerates. Upon acid treatment, the supramolecular threads could be disassembled to afford the free CNT-polymer hybrid, thus allowing recycling of the depolluting agent. All materials and complexation/decomplexation steps were thoroughly characterised by using thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), transmission and scanning electron microscopy (TEM and SEM, respectively). The quantification of the M(2+) residual concentrations in water was evaluated by using inductively coupled plasma optical emission spectroscopy (ICP-OES), which showed that, depending on the metal cation, this material can remove up to 99% of the contaminant. PMID:23239590

  14. Self-aligned nanogaps on multilayer electrodes for fluidic and magnetic assembly of carbon nanotubes.

    PubMed

    Shim, Joon S; Yun, Yeo-Heung; Cho, Wondong; Shanov, Vesselin; Schulz, Mark J; Ahn, Chong H

    2010-07-20

    A self-aligned nanogap between multiple metal layers has been developed using a new controlled undercut and metallization technique (CUMT), and practically applied for self-assembly of individual carbon nanotubes (CNTs) over the developed nanogap. This new method allows conventional optical lithography to fabricate nanogap electrodes and self-aligned patterns with nanoscale precision. The self-aligned nickel (Ni) pattern on the nanogap electrode works as an assembly spot where the residual iron (Fe) catalyst at the end of the CNT is magnetically captured. The captured CNT is forced to be aligned parallel to the flow direction by fluidic shear force. The combined forces of magnetic attraction and fluidic alignment provide massive self-assembly of CNTs at target positions. Both multiwalled nanotubes (MWNTs) and single walled nanotubes (SWNTs) were successfully assembled over the nanogap electrodes, and their electrical characteristics were fully characterized. The CNTs self-assembled on the developed electrodes with a nanogap and showed a very reliable and reproducible current-voltage (I-V) characteristic. The method developed in this work can envisage the mass fabrication of individual CNT-assembled devices which can be applied to nanoelectronic devices or nanobiosensors. PMID:20553000

  15. Carbon Nanotube Biosensors

    Microsoft Academic Search

    Pingang He; Liming Dai

    Owing to their nano-dimensions, rich electronic states, large surface area, high mechanical strength, and excellent chemical\\u000a and thermal stability, carbon nanotubes have attracted a great deal of interest [1]. Among the many potential applications [1, 2], carbon nanotubes have recently become promising functional materials for the development of advanced biosensors with novel\\u000a features. It has been demonstrated that carbon nanotubes

  16. Magnetic-field-induced diameter-selective synthesis of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Su, Yanjie; Zhang, Yaozhong; Wei, Hao; Zhang, Liling; Zhao, Jiang; Yang, Zhi; Zhang, Yafei

    2012-02-01

    We report a facile and scalable approach to synthesize single-walled carbon nanotubes (SWNTs) with selected diameter distribution by applying a magnetic field perpendicular to the electric field in the arc plasma region. It is found that this magnetic field-induced diameter-selectivity strategy enables the control of the SWNTs with different diameter distributions in different regions, and the diameter-selective efficiency could be enhanced by modifying the direction of magnetic field. Our results indicate that the motions of the catalysts with different particle sizes, positive carbon ions and electrons are significantly influenced by the magnetic field and electromagnetic force, resulting in the different nucleation and growth processes of SWNTs due to the collective interactions between the magnetic field and arc plasma. This approach would enable a viable route towards the synthesis of SWNTs with desired diameter through the tuning of arc parameters in the arc discharge process.We report a facile and scalable approach to synthesize single-walled carbon nanotubes (SWNTs) with selected diameter distribution by applying a magnetic field perpendicular to the electric field in the arc plasma region. It is found that this magnetic field-induced diameter-selectivity strategy enables the control of the SWNTs with different diameter distributions in different regions, and the diameter-selective efficiency could be enhanced by modifying the direction of magnetic field. Our results indicate that the motions of the catalysts with different particle sizes, positive carbon ions and electrons are significantly influenced by the magnetic field and electromagnetic force, resulting in the different nucleation and growth processes of SWNTs due to the collective interactions between the magnetic field and arc plasma. This approach would enable a viable route towards the synthesis of SWNTs with desired diameter through the tuning of arc parameters in the arc discharge process. Electronic supplementary information (ESI) available: Schematic diagram of SWNT sampling points, peak areas of S22 and M11 and relative ratios of S/M. See DOI: 10.1039/c2nr11783e

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

    SciTech Connect

    Huang, P; Schwegler, E; Galli, G

    2008-11-14

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

  18. Structure, composition and magnetic properties of carbon nanotubes doped by Fe during the growth process

    NASA Astrophysics Data System (ADS)

    Labunov, V. A.; Shulitski, B. G.; Prudnikava, A. L.; Yanushkevich, K. I.

    2008-03-01

    The results of complex investigations of the crystalline structure, composition and specific magnetization of the multi-wall carbon nanotubes (CNTs) filled by magnetic nanocomposite are performed. CNT arrays have been synthesized by the high temperature pyrolysis of fluid hydrocarbon - p-xylole [C8H10] in the presence of volatile catalyst - ferrocene [Fe(C5H5)2] at the walls of tubular-type quartz reactor of specially constructed equipment. It was revealed that the obtained CNTs constitute complex nanocomposite: C - Fe3C - Fe5C2 - Fe. The magnetic properties of such CNTs in the temperature region of 78<=T<=1060 K are conditioned by the ferric carbide (in the form Fe3C H Fe5C2) and Fe.

  19. Magnetic field effects and renormalization of the long-range Coulomb interaction in carbon nanotubes

    SciTech Connect

    Bellucci, S. [INFN, Laboratori Nazionali di Frascati, P.O. Box 13, 00044 Frascati (Italy)]. E-mail: Stefano.Bellucci@lnf.infn.it; Onorato, P. [INFN, Laboratori Nazionali di Frascati, P.O. Box 13, 00044 Frascati (Italy); Dipartimento di Scienze Fisiche, Universita di Roma Tre, Via della Vasca Navale 84, 00146 Rome (Italy)

    2006-04-15

    We develop two theoretical approaches for dealing with the low-energy effects of the repulsive interaction in one-dimensional electron systems. Renormalization Group methods allow us to study the low-energy behavior of the unscreened interaction between currents of well-defined chirality in a strictly one-dimensional electron system. A dimensional regularization approach is useful, when dealing with the low-energy effects of the long-range Coulomb interaction. This method allows us to avoid the infrared singularities arising from the long-range Coulomb interaction at D = 1. We can also compare these approaches with the Luttinger model, to analyze the effects of the short-range term in the interaction. Thanks to these methods, we are able to discuss the effects of a strong magnetic field B in quasi one-dimensional electron systems, by focusing our attention on Carbon Nanotubes. Our results imply a variation with B in the value of the critical exponent {alpha} for the tunneling density of states, which is in fair agreement with that observed in a recent transport experiment involving carbon nanotubes. The dimensional regularization allows us to predict the disappearance of the Luttinger liquid, when the magnetic field increases, with the formation of a chiral liquid with {alpha} = 0.

  20. Nuclear Magnetic Resonance Spectroscopy and Imaging of Carbon Nanotubes

    Microsoft Academic Search

    Vijay K. Anuganti; Aldrik H. Velders

    \\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

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

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Oliveira, L.; Podila, R.; Neeleshwar, S.; Chen, Y. Y.; He, J.; Skove, M.; Rao, A. M.; Department of Physics and Astronomy, Clemson University Collaboration; Institute of Physics, Academia Sinica Collaboration

    2013-03-01

    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 °C 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.

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

    PubMed

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

    2014-11-25

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

  3. Introduction to Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

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

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

  4. Electron field emission from magnetic nanomaterial encapsulated multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Rakhi, R. B.; Lim, X.; Gao, X.; Wang, Y.; Wee, A. T. S.; Sethupathi, K.; Ramaprabhu, S.; Sow, C. H.

    2010-01-01

    The present work describes the field emission characteristics of nanoscale magnetic nanomaterial encapsulated multi-walled carbon nanotubes (MWNTs) fabricated over flexible graphitized carbon cloth. Ni/MWNTs, NiFe/MWNTs and NiFeCo/MWNTs have been synthesized by catalytic chemical vapor decomposition of methane over Mischmetal (Mm)-based AB3 (MmNi3, MmFe1.5Ni1.5 and MmFeCoNi) alloy hydride catalysts. Metal-encapsulated MWNTs exhibited superior field emission performance than pure MWNT-based field emitters over the same substrate. The results indicate that a Ni-filled MWNT field emitter is a promising material for practical field emission application with a lowest turn-on field of 0.6 V/?m and a high emission current density of 0.3 mA/cm2 at 0.9 V/?m.

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

    PubMed Central

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

    2012-01-01

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

  6. Simultaneous synthesis of single-walled carbon nanotubes and graphene in a magnetically-enhanced arc plasma.

    PubMed

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

    2012-01-01

    Carbon nanostructures such as single-walled carbon nanotubes (SWCNT) and graphene attract a deluge of interest of scholars nowadays due to their very promising application for molecular sensors, field effect transistor and super thin and flexible electronic devices(1-4). Anodic arc discharge supported by the erosion of the anode material is one of the most practical and efficient methods, which can provide specific non-equilibrium processes and a high influx of carbon material to the developing structures at relatively higher temperature, and consequently the as-synthesized products have few structural defects and better crystallinity. To further improve the controllability and flexibility of the synthesis of carbon nanostructures in arc discharge, magnetic fields can be applied during the synthesis process according to the strong magnetic responses of arc plasmas. It was demonstrated that the magnetically-enhanced arc discharge can increase the average length of SWCNT (5), narrow the diameter distribution of metallic catalyst particles and carbon nanotubes (6), and change the ratio of metallic and semiconducting carbon nanotubes (7), as well as lead to graphene synthesis (8). Furthermore, it is worthwhile to remark that when we introduce a non-uniform magnetic field with the component normal to the current in arc, the Lorentz force along the J×B direction can generate the plasmas jet and make effective delivery of carbon ion particles and heat flux to samples. As a result, large-scale graphene flakes and high-purity single-walled carbon nanotubes were simultaneously generated by such new magnetically-enhanced anodic arc method. Arc imaging, scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscopy were employed to analyze the characterization of carbon nanostructures. These findings indicate a wide spectrum of opportunities to manipulate with the properties of nanostructures produced in plasmas by means of controlling the arc conditions. PMID:22330847

  7. Effect of sulfur on enhancing nitrogen-doping and magnetic properties of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cui, Tongxiang; Lv, Ruitao; Huang, Zheng-Hong; Kang, Feiyu; Wang, Kunlin; Wu, Dehai

    2011-12-01

    Sulfur (S) is introduced as an additive in the growth atmosphere of carbon nanotubes (CNTs) in the range of 940-1020°C. CNT products with distorted sidewalls can be obtained by S-assisted growth. Moreover, many fascinating CNT structures can also be found in samples grown with S addition, such as bamboo-like CNTs, twisted CNTs, arborization-like CNTs, and bead-like CNTs. Compared with CNTs grown without S, more nitrogen-doping content is achieved in CNTs with S addition, which is beneficial for the properties and applications of nitrogen-doped CNTs. In addition, S can also enhance the encapsulation of ferromagnetic materials and thus improve the soft magnetic properties of CNTs, which is favorable to the applications of CNTs in the electromagnetic wave-absorbing and magnetic data storage areas.

  8. Study in synthesis and characterization of carbon nanotubes decorated by magnetic iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Sadegh, Hamidreza; Shahryari-ghoshekandi, Ramin; Kazemi, Maryam

    2014-10-01

    Magnetic nanoparticles iron oxide with average sizes of 6 nm were synthesized by a chemical coprecipitation method from mixtures of FeCl2·4H2O and FeCl3·6H2O. For preparation, multi-walled carbon nanotubes (MWCNTS) with outer diameter of 50 nm, wall thickness from 1 to 2 nm and length from 500-2,000 nm were used. Characterization of the MWCNT-Fe3O4 by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), thermo-gravimetric analysis (TGA) and magnetic characterization was conducted on a vibrating sample magnetometer (VSM).

  9. Iron filled carbon nanotubes grown on substrates with thin metal layers and their magnetic properties

    Microsoft Academic Search

    C. Müller; S. Hampel; D. Elefant; K. Biedermann; A. Leonhardt; M. Ritschel; B. Büchner

    2006-01-01

    The thermal decomposition of ferrocene combined with a catalyst-assisted structuring of a Si-substrate surface is a favourable way to produce Fe-filled carbon nanotubes in good quality and in high yields. In this work we have studied the growth of such aligned filled nanotubes on iron and cobalt pre-coated Si-substrates and their dependence on the deposition time. The nanotube diameter depends

  10. Surfactant free magnetic nanofluids based on core-shell type nanoparticle decorated multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Theres Baby, Tessy; Sundara, Ramaprabhu

    2011-09-01

    Magnetic nanofluids consisting of fluids suspended with magnetic materials are of current interest and have potential applications in both energy related and biomedical fields. In this paper, we present a novel magnetic nanofluid obtained by dispersing silicon dioxide (SiO2) coated on magnetite (Fe3O4) particle decorated multiwalled carbon nanotubes (MWNTs) (Fe3O4@SiO2/MWNTs) in de-ionized water. As compared to a magnetite decorated MWNT based nanofluid, the present system shows better stability and thermal properties without the use of any surfactants. Fe3O4/MWNTs and Fe3O4@SiO2/MWNTs have been synthesized via a simple chemical reduction technique and dispersed in de-ionized water via ultrasonication. Dispersed de-ionized water based nanofluids containing Fe3O4/MWNTs with surfactant and Fe3O4@SiO2/MWNTs without surfactant show a thermal conductivity enhancement of 20% and 24.5%, respectively, for a volume fraction of 0.03% in the presence of magnetic field. The enhancement in the thermal conductivity has been observed for other volume fractions also. The increase in the thermal conductivity of these nanofluids can be attributed to the chain formation of magnetic nanomaterials in the base fluid in the presence of magnetic field.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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.

  12. Nanomanipulation and Lithography: The Building (and Modeling) of Carbon Nanotube Magnetic Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Louie, Richard Nam

    2002-12-01

    Aircraft fuselages suffer alternating stress during takeoffs and landings, and fatigue cracks begin to grow, usually at rivet holes. The detection of these fatigue cracks under installed fasteners in aging aircraft is a major goal of the nondestructive evaluation (NDE) community. The use of giant magnetoresistance (GMR) sensors in electromagnetic (EM) NDE has been increasing rapidly. For example, here at Langley Research Center, a Rotating Probe System (RPS) containing a GMR element has been incorporated into a product to detect deeply buried flaws in aerospace structures. In order to advance this eddy current probe application and many similar ones, research to create smaller, more sensitive and energy-efficient EM sensors has been aggressively pursued. Recent theoretical and experimental work on spin coherent transport supports the feasibility of carbon nanotube (CNT) based magnetic tunnel junctions. In this study, a spatial filtering scheme is presented that improves the signal to noise ratio of the RPS and does not significantly impact the number of false alarms. Signals due to buried flaws occur at higher frequencies than do signals due to rivet tilt or probe misalignment, and the strategy purposefully targets this fact. Furthermore, the spatial filtering scheme exploits decreases in the probe output that are observed immediately preceding and following the peak in output due to a fatigue crack. Using the new filters, an enhanced probability of flaw detection is expected. In the future, even tinier, more sensitive, low-power sensors are envisioned for the rotating probe and other nondestructive inspection systems. These may be comprised of single-walled carbon nanotubes (SWCNTs) that connect two ferromagnetic (FM) electrodes. Theoretical work has been done at Langley to model the electrical and magnetoconductance behavior of such junctions, for systems containing short "armchair" nanotubes. The present work facilitates the modeling of more realistic system sizes, through the re-writing of a critical code segment that gives a hundredfold improvement in speed. Furthermore, the tight-binding model calculations are now generalized to include all types of nanotubes, not merely armchair tubes. On the experimental side, innovative junction fabrication procedures are investigated, including diamond-tip scanning probe lithography and e-beam lithography. Programs are written for the Nanometer Pattern Generation System to effect the creation of many junctions at once, to increase the chances of a CNT connecting two FM electrodes. As it is not prudent to rely solely on luck, the capability for tube nanomanipulation with an unprecedented level of control is also shown, and a procedure for controlled deposition upon chemically functionalized lithographic patterns is discussed. All of the techniques demonstrated can be used to create a magnetic tunnel junction to be refrigerated for extensive magnetoconductance studies.

  13. 3d metal nanowires and clusters inside carbon nanotubes: Structural, electronic, and magnetic properties

    Microsoft Academic Search

    Viktoria V. Ivanovskaya; Christof Köhler; Gotthard Seifert

    2007-01-01

    The structure and the properties of the quasi-one-dimensional composites, i.e., carbon nanotubes filled with nanowires or clusters of 3d metals ( M=Ti , Fe, and Zn), have been studied in the framework of the density functional-based tight binding method. We show that the accommodation of nanosized metal species inside carbon nanotubes (CNTs) may lead to essential changes of the structural,

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

    NASA Astrophysics Data System (ADS)

    Shaver, J.; Crooker, S. A.; Fagan, J. A.; Hobbie, E. K.; Ubrig, N.; Portugall, O.; Perebeinos, V.; Avouris, Ph.; Kono, J.

    2008-08-01

    We have investigated excitons in highly aligned single-walled carbon nanotubes (SWCNTs) through optical spectroscopy at low temperatures down to 1.5 K and high magnetic fields (B) up to 55 T. SWCNT/polyacrylic acid films were stretched, giving SWCNTs that are highly aligned along the direction of stretch (n?) . Utilizing two well-defined measurement geometries, n??B and n??B , we provide unambiguous evidence that the photoluminescence energy and intensity are only sensitive to the B -component parallel to the tube axis. A theoretical model of one-dimensional magnetoexcitons, based on exchange-split “bright” and “dark” exciton bands with Aharonov-Bohm-phase-dependent energies, masses, and oscillator strengths, successfully reproduces our observations and allows determination of the splitting between the two bands as ˜4.8meV for (6,5) SWCNTs.

  15. Carbon Nanotubes in Neuroscience

    PubMed Central

    Malarkey, Erik B.

    2010-01-01

    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

  16. Water-dispersible magnetic carbon nanotubes as T2-weighted MRI contrast agents.

    PubMed

    Liu, Yue; Hughes, Timothy C; Muir, Benjamin W; Waddington, Lynne J; Gengenbach, Thomas R; Easton, Christopher D; Hinton, Tracey M; Moffat, Bradford A; Hao, Xiaojuan; Qiu, Jieshan

    2014-01-01

    An efficient MRI T2-weighted contrast agent incorporating a potential liver targeting functionality was synthesized via the combination of superparamagnetic iron oxide (SPIO) nanoparticles with multiwalled carbon nanotubes (MWCNTs). Poly(diallyldimethylammonium chloride) (PDDA) was coated on the surface of acid treated MWCNTs via electrostatic interactions and SPIO nanoparticles modified with a potential targeting agent, lactose-glycine adduct (Lac-Gly), were subsequently immobilized on the surface of the PDDA-MWCNTs. A narrow magnetic hysteresis loop indicated that the product displayed superparamagnetism at room temperature which was further confirmed by ZFC (zero field cooling)/FC (field cooling) curves measured by SQUID. The multifunctional MWCNT-based magnetic nanocomposites showed low cytotoxicity in vitro to HEK293 and Huh7 cell lines. Enhanced T2 relaxivities were observed for the hybrid material (186 mM(-1) s(-1)) in comparison with the pure magnetic nanoparticles (92 mM(-1) s(-1)) due to the capacity of the MWCNTs to "carry" more nanoparticles as clusters. More importantly, after administration of the composite material to an in vivo liver cancer model in mice, a significant increase in tumor to liver contrast ratio (277%) was observed in T2 weighted magnetic resonance images. PMID:24120046

  17. Carbon Nanotube Memory Elements

    SciTech Connect

    Meunier, Vincent [ORNL; Sumpter, Bobby G [ORNL

    2010-01-01

    Carbon nanotubes are among the most cited prototypical materials for nanoelectronics and information storage devices, a dominant position that originates from their intrinsic structural and electronic properties. In this chapter we review the developments in memory elements that directly exploit the unique properties of carbon nanotubes. Fundamental operational principles and characteristics are examined for the different types of carbon nanotube-based memory devices along with the current status of experimental fabrication and scalability. These include memory elements based on carbon nanotube field-effect transistors (CNFET), nanoelectromechanical systems (NEMS), and electromigration. Many of these devices show tremendous promise for providing enhanced densities, lower power requirements, more efficient read/write processes, and non-volatility of data.

  18. Carbon nanotubes: Fibrillar pharmacology

    NASA Astrophysics Data System (ADS)

    Kostarelos, Kostas

    2010-10-01

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

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

    PubMed

    Zohdi, Nima; Mahdavi, Fariba; Abdullah, Luqman Chuah; Choong, Thomas Sy

    2014-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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.

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

    PubMed Central

    2014-01-01

    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

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

    E-print Network

    Krasheninnikov, Arkady V.

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

  3. Poly( l-lactide) brushes on magnetic multiwalled carbon nanotubes by in-situ ring-opening polymerization

    Microsoft Academic Search

    Jiangtao Feng; Wei Cai; Jiehe Sui; Zhiguo Li; Jiaqi Wan; Ali Nabipour Chakoli

    2008-01-01

    Biodegradable poly(l-lactide) (PLLA) has been covalently grafted onto the surface of magnetic multiwalled carbon nanotubes (m-MWCNTs) by in-situ ring-opening polymerization of lactide. The content of grafting PLLA can be controlled by adjusting the feed ratio of monomer to m-MWCNTs. FT-IR and Raman spectroscopy confirm that PLLA have been covalently attached to the sidewalls of m-MWCNTs. Thermal gravimetric analysis (TGA) indicates

  4. Irradiation Stability of Carbon Nanotubes 

    E-print Network

    Aitkaliyeva, Assel

    2010-01-14

    Ion irradiation of carbon nanotubes is a tool that can be used to achieve modification of the structure. Irradiation stability of carbon nanotubes was studied by ion and electron bombardment of the samples. Different ion ...

  5. Sensor applications of carbon nanotubes

    E-print Network

    Rushfeldt, Scott I

    2005-01-01

    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, ...

  6. Magnetic properties and transmission electron microscopy studies of Ni nanoparticles encapsulated in carbon nanocages and carbon nanotubes

    Microsoft Academic Search

    Chunnian He; Naiqin Zhao; Chunsheng Shi; Jiajun Li; Haipeng Li

    2008-01-01

    Three types of carbon nanomaterials, including bamboo-shaped carbon nanotubes with Ni encapsulated and hollow and Ni catalytic particles filled carbon nanocages, have been prepared by methane catalytic decomposition at a relatively low temperature. Transmission electron microscopy observations showed that fascinating fullerene-like Ni–C (graphitic) core–shell nanostructures predominated. Detailed examination of high-resolution transmission electron microscopy showed that the walls of bamboo-shaped carbon

  7. Carbon Nanotube Linear Bearing Nanoswitches

    E-print Network

    Bockrath, Marc

    Carbon Nanotube Linear Bearing Nanoswitches V. V. Deshpande, H.-Y. Chiu, H. W. Ch. Postma, C. Miko-friction bearing capabilities of multiwalled carbon nanotubes (MWNTs) to realize nanoelectromechanical switches bearing capabilities3-5 of multi- and double-walled carbon nanotubes (MWNTs and DWNTs) to realize

  8. Magnetic Brightening of Dark Excitons in Individual Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Srivastava, Ajit; Kono, Junichiro; Htoon, Han; Klimov, Victor I.

    2008-03-01

    We have performed micro-photoluminescence (PL) studies on individual single-walled carbon nanotubes (SWNTs) at varying temperatures (T = 4 K -- 100 K) in magnetic fields (B) up to 5 T, which provide direct evidence for the existence of dark excitons in SWNTs. Only when the B was parallel to the tube axis, we observed the appearance of a secondary peak at a lower energy with respect to the main emission peak. The secondary peak increased in intensity with increasing B at the expense of the main peak. At the lowest T, a complete reversal of emission intensity from the main peak to the side peak was seen as the B was increased. However, the main peak was recovered as the T was increased at a fixed B. These behaviors can be explained by assigning the main and secondary peaks to the lowest-energy bright and dark singlet exciton states, respectively. The absence of these behaviors in B perpendicular to the tube axis convincingly suggests that brightening is induced by the Aharonov-Bohm phase. The zero-field dark-bright splitting is found to be ˜1-2 meV, which is lower than most theoretical predictions.

  9. Artifact properties of carbon nanotube yarn electrode in magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  10. Structural and magnetic characterization of batch-fabricated nickel encapsulated multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zeeshan, M. A.; Shou, K.; Pané, S.; Pellicer, E.; Sort, J.; Sivaraman, K. M.; Baró, M. D.; Nelson, B. J.

    2011-07-01

    We report on the growth and fabrication of Ni-filled multi-walled carbon nanotubes (Ni-MWNTs) with an average diameter of 115 nm and variable length of 400 nm-1 µm. The Ni-MWNTs were grown using template-assisted electrodeposition and low pressure chemical vapor deposition (LPCVD) techniques. Anodized alumina oxide (AAO) templates were fabricated on Si using a current controlled process. This was followed by the electrodeposition of Ni nanowires (NWs) using galvanostatic pulsed current (PC) electrodeposition. Ni NWs served as the catalyst to grow Ni-MWNTs in an atmosphere of H2/C2H2 at a temperature of 700 °C. Time dependent depositions were carried out to understand the diffusion and growth mechanism of Ni-MWNTs. Characterization was carried out using scanning electron microscopy (SEM), focused ion beam (FIB) milling, transmission electron microscopy (TEM), Raman spectroscopy and energy dispersive x-ray spectroscopy (EDX). TEM analysis revealed that the Ni nanowires possess a fcc structure. To understand the effects of the electrodeposition parameters, and also the effects of the high temperatures encountered during MWNT growth on the magnetic properties of the Ni-MWNTs, vibrating sample magnetometer (VSM) measurements were performed. The template-based fabrication method is repeatable, efficient, enables batch fabrication and provides good control on the dimensions of the Ni-MWNTs.

  11. Transport Through Carbon Nanotube Wires

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  12. Carbon Nanotube Transistors

    NASA Astrophysics Data System (ADS)

    Datta, Supriyo

    2003-03-01

    Carbon nanotube transistors (CNTFETs) with performance greatly exceeding silicon MOSFETs have recently been demonstrated. In order to explore potential applications of CNT technologies in future nanoelectronic systems, it is important to understand the device physics and evaluate the upper limit for the performance of CNTFETs. We will present a theoretical evaluation of ballistic CNTFET's using both (1) a detailed atomistic model and (2) a simple, phenomenological model. CNTFETs present the possibility of achieving both the ballistic and quantum capacitance limits, leading to several interesting effects. For example, the transconductance, gm, is identical to the channel conductance, GD, and quantized in units of 4e^2/h. An analysis of recent experiments indicates that present-day CNTFET's still operate well below their performance limit due to parasitic resistance and scattering. Possible approaches for improving the performance will be discussed. References: [1] Jing Guo, Supriyo Datta, and Mark Lundstrom, Markus Brink and Paul McEuen, Ali Javey, Hongjie Dai, Hyoungsub Kim, and Paul McIntyre,"Assessment of Silicon MOS and Carbon Nanotube FET Performance LimitsUsing a General Theory of Ballistic Transistors", to appear in IEDM Proceedings, 2002. [2] Jing Guo, Sebastien Goasguen, Mark Lundstrom, and Supriyo Datta, "Metal-insulator-semiconductor electrostatics of carbon nanotubes" Appl. Phys. Lett., 81, 1486 (2002). [3] Jing Guo, Mark Lundstrom, and Supriyo Datta, "Performance Projections for Ballistic Carbon Nanotube Field-Effect Transistors", Appl. Phys. Lett., 80, 3192 (2002).

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

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

    PubMed Central

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

    2014-01-01

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

  15. AC magnetic field-assisted method to develop porous carbon nanotube/conducting polymer composites for application in thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Chuang, Chun-Yu; Yang, Shu-Chian; Chang, Su-Hua; Yang, Ta-I.

    2015-04-01

    Thermoelectric materials are very effective in converting waste heat sources into useful electricity. Researchers are continuing to develop new polymeric thermoelectric materials. The segregated-network carbon nanotube (CNT)- polymer composites are most promising. Thus, the goal of this study is to develop novel porous CNT -polymer composites with improved thermoelectric properties. The research efforts focused on modifying the surface of the CNT with magnetic nanoparticles so that heat was released when subjecting to an AC magnetic field. Subsequently, polymers covered on the surface of the CNT were crosslinked. The porous CNT -polymer composites can be obtained by removing the un-crosslinked polymers. Polydimethylsiloxane polymer was utilized to investigate the effect of porosity and electrical conductivity on the thermoelectric properties of the composites. This AC magnetic field-assisted method to develop porous carbon nanotube/polymer composites for application in thermoelectric materials is introduced for the first time. The advantage of this method is that the electrical conductivity of the composites was high since we can easily to manipulate the CNT to form a conducting path. Another advantage is that the high porosity significantly reduced the thermal conductivity of the composites. These two advantages enable us to realize the polymer composites for thermoelectric applications. We are confident that this research will open a new avenue for developing polymer thermoelectric materials.

  16. Method of manufacturing carbon nanotubes

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    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.

  17. Highly efficient molecular delivery into mammalian cells using carbon nanotube spearing

    E-print Network

    Cai, Long

    Highly efficient molecular delivery into mammalian cells using carbon nanotube spearing Dong Cai1. Vertically aligned carbon nanotubes grown by plasma-enhanced chemical vapor deposition (PECVD)1 have to magnetic agitation. The momentum of the carbon nanotubes can be used to penetrate cell membranes (nanotube

  18. Carbon nanotube network varactor

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  19. Carbon nanotube network varactor.

    PubMed

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

    2015-01-30

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

  20. Carbon nanotube plane fastener

    NASA Astrophysics Data System (ADS)

    Hirahara, Kaori; Ajioka, Shoichi; Nakayama, Yoshikazu

    2011-12-01

    We report a feature of carbon nanotubes (CNTs) that arises when the surfaces of two vertically-aligned CNT brushes are pressed together. Adhesion between the CNTs creates a plane fastener-like device. Observations from scanning electron microscopy and measurements of adhesion properties indicate a device-dependence on CNT density and shape near the tip region. Among other applications, such fasteners have the potential to attach small components onto micron-sized electronic devices.

  1. Carbon nanotubes for optical limiting

    Microsoft Academic Search

    L Vivien; P Lançon; D Riehl; F Hache; E Anglaret

    2002-01-01

    This paper reviews the optical limiting properties of carbon nanotubes. The nonlinear optical properties of nanotubes were investigated in water and in chloroform suspensions. Nonlinear transmittance measurements were reported for various pulse durations and wavelengths and show that carbon nanotubes are good candidates for effective optical limiting over broad temporal and laser energy ranges. Z-Scans and pump-probe time-resolved experiments were

  2. Torsional Electromechanics of Carbon Nanotubes

    Microsoft Academic Search

    Ernesto Joselevich; Tzahi Cohen-Karni; Lior Segev; Onit Srur-Lavi; Sidney R. Cohen

    2007-01-01

    Carbon nanotubes are known to be distinctly metallic or semiconducting depending on their diameter and chirality. Here we show that continuously varying the chirality by mechanical torsion can induce conductance oscillations, which can be attributed to metal-semiconductor periodic transitions. The phenomenon is observed in multi-walled carbon nanotubes, where both the torque and the current are shown to be carried predominantly

  3. Carbon nanotubes: opportunities and challenges

    Microsoft Academic Search

    Hongjie Dai

    2002-01-01

    Carbon nanotubes are graphene sheets rolled-up into cylinders with diameters as small as one nanometer. Extensive work carried out worldwide in recent years has revealed the intriguing electrical and mechanical properties of these novel molecular scale wires. It is now well established that carbon nanotubes are ideal model systems for studying the physics in one-dimensional solids and have significant potential

  4. Fundamental transmitting properties of carbon nanotube antennas

    Microsoft Academic Search

    G. W. Hanson

    2005-01-01

    Fundamental properties of dipole transmitting antennas formed by carbon nanotubes are investigated. Since carbon nanotubes can be grown to centimeter lengths, and since they can be metallic, the properties of carbon nanotubes as antenna elements are of fundamental interest. In this paper, dipole carbon nanotube antennas are investigated via a classical Hallen's-type integral equation, based on a quantum mechanical conductivity.

  5. Carbon-Nanotube Optoelectronics

    Microsoft Academic Search

    Phaedon Avouris; Marcus Freitag; Vasili Perebeinos

    \\u000a Semiconducting single-walled carbon nanotubes are direct-gap materials that\\u000a provide ideal systems for the study of photophysics in one-dimension. While\\u000a their excited states involve strongly bound 1D excitons, their single atomic\\u000a layer structure makes their optical properties especially sensitive to their\\u000a environment and external fields, thus allowing for their controlled modification. In\\u000a this chapter we review the properties of the excited

  6. Conductivity and Magnetic Susceptibility of Nanotube\\/Polypyrrole Nanocomposites

    Microsoft Academic Search

    B. H. Chang; Z. Q. Liu; L. F. Sun; D. S. Tang; W. Y. Zhou; G. Wang; L. X. Qian; S. S. Xie; J. H. Fen; M. X. Wan

    2000-01-01

    A method has been developed to produce a carbon nanotube\\/conducting polymer nano-composite through in-situ polymerization of pyrrole in the carbon nanotube template. The nano-composites of carbon nanotube and polypyrrole have been characterized by SEM, TEM, XRD, Raman Scattering. The thermal stability was studied by TGA (Thermal Gravity Analysis). The measurements of conductivity and magnetic susceptibility of the composites have been

  7. Conductivity and magnetic susceptibility of nanotube/polypyrrole nanocomposites

    SciTech Connect

    Chang, B.H.; Liu, Z.Q.; Sun, L.F. [and others] [and others

    2000-04-01

    A method has been developed to produce a carbon nanotube/conducting polymer nano-composite through in-situ polymerization of pyrrole in the carbon nanotube template. The nano-composites of carbon nanotube and polypyrrole have been characterized by SEM, TEM, XRD, Raman Scattering. The thermal stability was studied by TGA (Thermal Gravity Analysis). The measurements of conductivity and magnetic susceptibility of the composites have been studied.

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

    PubMed

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

    2011-09-01

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

  9. Polymer nanocomposites based on functionalized carbon nanotubes

    Microsoft Academic Search

    Nanda Gopal Sahoo; Sravendra Rana; Jae Whan Cho; Lin Li; Siew Hwa Chan

    2010-01-01

    Carbon nanotubes (CNTs) exhibit excellent mechanical, electrical, and magnetic properties as well as nanometer scale diameter and high aspect ratio, which make them an ideal reinforcing agent for high strength polymer composites. However, since CNTs usually form stabilized bundles due to Van der Waals interactions, are extremely difficult to disperse and align in a polymer matrix. The biggest issues in

  10. Supramolecular chemistry of carbon nanotubes.

    PubMed

    Gavrel, Gildas; Jousselme, Bruno; Filoramo, Arianna; Campidelli, Stéphane

    2014-01-01

    This chapter aims to present recent examples of supramolecular functionalization of carbon nanotubes. The non-covalent functionalization appears as a solution for the future applications in nanotechnologies since it allows the functionalization and manipulation of nanotubes without the introduction of sp (3) defects in the ?-conjugated system. Thus, the optical and electronic properties of the nanotubes remain preserved. In the first part of this chapter, we present the use of surfactant for the dispersion of nanotubes and its application for sorting. Then we report several examples of functionalization of nanotubes based on ?-stacking interactions with pyrene derivatives. Finally, in the last part we review the wrapping of photo/electroactive polymers around the nanotube sidewalls. We put a particular focus on polyflurorene-based polymers and we show their utilization for the separation of nanotubes in diameter and chirality. PMID:23756847

  11. Method for synthesizing carbon nanotubes

    DOEpatents

    Fan, Hongyou

    2012-09-04

    A method for preparing a precursor solution for synthesis of carbon nanomaterials, where a polar solvent is added to at least one block copolymer and at least one carbohydrate compound, and the precursor solution is processed using a self-assembly process and subsequent heating to form nanoporous carbon films, porous carbon nanotubes, and porous carbon nanoparticles.

  12. Biophilic carbon nanotubes.

    PubMed

    Mallick, Kaushik; Strydom, André M

    2013-05-01

    Carbon nanotubes (CNTs) have been proposed and are actively being explored as innovative multipurpose carriers for biomolecules and diagnostic applications. Their versatile physico-chemical features enable them as a carrier of several pharmaceutically relevant entities and allow them for rational design of novel nanoscale candidates for drug development. Functionalized carbon nanotubes (f-CNT) are emerging as a new family of nanovectors for the delivery of different types of therapeutic molecules. The application of CNTs in the field of carrier-mediated delivery has become possible after the recent discovery of their capacity to penetrate into the cells. CNT can be loaded with active molecules by forming stable covalent bonds or supramolecular assemblies based on noncovalent interactions. Once the cargos are carried into various cells, tissues and organs they are able to express their biological function. In this review, we will describe the potential of f-CNT as a vehicle to deliver different types of therapeutic agents into the biological species. PMID:23384693

  13. Nanotechnology: Spinning continuous carbon nanotube yarns

    Microsoft Academic Search

    Kaili Jiang; Qunqing Li; Shoushan Fan

    2002-01-01

    The creation of continuous yarns made out of carbon nanotubes would enable macroscopic nanotube devices and structures to be constructed. Here we show that carbon nanotubes can be self-assembled into yarns of up to 30 cm in length simply by being drawn out from superaligned arrays of carbon nanotubes, and that the strength and conductivity of these yarns can be

  14. Method for producing carbon nanotubes

    DOEpatents

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

    2006-02-14

    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.

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

    PubMed

    Ma, Guifu; Chen, Ligang

    2014-02-14

    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

  16. Torsional Electromechanics of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Joselevich, Ernesto; Cohen-Karni, Tzahi; Segev, Lior; Srur-Lavi, Onit; Cohen, Sidney R.

    2007-03-01

    Carbon nanotubes are known to be distinctly metallic or semiconducting depending on their diameter and chirality. Here we show that continuously varying the chirality by mechanical torsion can induce conductance oscillations, which can be attributed to metal-semiconductor periodic transitions. The phenomenon is observed in multi-walled carbon nanotubes, where both the torque and the current are shown to be carried predominantly by the outermost wall. The oscillation period with torsion is consistent with the theoretical shifting of the corners of the first Brillouin zone of graphene across different subbands allowed in the nanotube. Beyond a critical torsion, the conductance irreversibly drops due to torsional failure, allowing us to determine the torsional strength of carbon nanotubes. Our experiments indicate that carbon nanotubes could be used as self-sensing torsional springs for nanoelectromechanical systems (NEMS). [1] E. Joselevich, Twisting nanotubes: From torsion to chirality, ChemPhysChem 2006, 7, 1405. [2] T. Cohen-Karni, L. Segev, O. Srur-Lavi, S. R. Cohen, E. Joselevich, Torsional electromechanical quantum oscillations in carbon nanotubes, Nature Nanotechnology, 2006, 1, 36.

  17. Increasing carbon nanotube forest density

    E-print Network

    McCarthy, Alexander P

    2014-01-01

    The outstanding mechanical, electrical, thermal, and morphological properties of individual carbon nanotubes (CNTs) open up exciting potential applications in a wide range of fields. One such application is replacing the ...

  18. Carbon nanotube stabilized conductive polymers

    NASA Astrophysics Data System (ADS)

    Li, Yi-Fan; Wong, I.-Sing; Lai, Tao-Cheng; Chin, Wei; Hsu, Wen-Kuang

    2010-10-01

    Carbon nanotubes act as radical scavengers in UV-irradiated conductive polymer (poly3,4-ethylenedioxythiophene:polystyrene sulfonate) and effect is verified by conductivity, electron paramagnetic resonance, and infrared absorption data.

  19. Carbon nanotubes: Captured on camera

    NASA Astrophysics Data System (ADS)

    Graham, Matt W.

    2013-12-01

    Images of individual carbon nanotubes with their respective optical spectra for chirality characterization are acquired directly on devices and growth substrates using a reflective polarized light microscopy set-up.

  20. Emerging Applications of Carbon Nanotubes

    E-print Network

    Schnorr, Jan Markus

    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 ...

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

    PubMed Central

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

    2015-01-01

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

  2. Thermal Properties of Carbon Nanotubes

    Microsoft Academic Search

    Mohamed. Osman; Aron W. Cummings; Deepak Srivastava

    The experimental observation of carbon nanotubes by Sumio Iijima in 1991 [1], sparked a significant effort in theoretical\\u000a and experimental investigation of carbon nanotubes and related structures. The studies of thermal properties, although very\\u000a important from fundamental and applications points of view, have received less attention in comparison with other aspects\\u000a such as the electrical and mechanical properties [2–18]. This

  3. Carbon nanotube electron gun

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

  4. Carbon Nanotube Electron Gun

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    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.

  5. Carbon Nanotube based Nanotechnolgy

    NASA Astrophysics Data System (ADS)

    Meyyappan, M.

    2000-10-01

    Carbon nanotube(CNT) was discovered in the early 1990s and is an off-spring of C60(the fullerene or buckyball). CNT, depending on chirality and diameter, can be metallic or semiconductor and thus allows formation of metal-semiconductor and semiconductor-semiconductor junctions. CNT exhibits extraordinary electrical and mechanical properties and offers remarkable potential for revolutionary applications in electronics devices, computing and data storage technology, sensors, composites, storage of hydrogen or lithium for battery development, nanoelectromechanical systems(NEMS), and as tip in scanning probe microscopy(SPM) for imaging and nanolithography. Thus the CNT synthesis, characterization and applications touch upon all disciplines of science and engineering. A common growth method now is based on CVD though surface catalysis is key to synthesis, in contrast to many CVD applications common in microelectronics. A plasma based variation is gaining some attention. This talk will provide an overview of CNT properties, growth methods, applications, and research challenges and opportunities ahead.

  6. Carbon nanotube terahertz detector.

    PubMed

    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

    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

  7. Sonoluminescence of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Roslyak, Oleksiy; Andrei, Piryatinski

    2014-03-01

    We report strong reduction in photoluminescence spectra of single wall semiconducting carbon nanotubes in presence of surface acoustical wave (SAW) in a piezoelectric substrate. In conventional Stark effect the excitonic oscillator strength is effectively transferred to the electron-hole manifold by reducing the exciton binding energy. Or formalism attributes the reduction to an effective damping of the electron velocity matrix elements at the Van Hove singularities of the SAW induced super-lattice. The effect manifests itself in absorption spectra by reducing the peaks amplitudes linearly with SAW amplitude in the GHz acoustical regime. Crossover to the Stark-like quadratic dependence on SAW amplitude occurs in low THz regime. We also report better quenching of higher order exciton absorption peaks as compared to the lowest optically active exciton.

  8. Dispersible carbon nanotubes.

    PubMed

    Soulié-Ziakovic, Corinne; Nicolaÿ, Renaud; Prevoteau, Alexandre; Leibler, Ludwik

    2014-01-27

    A method is proposed to produce nanoparticles dispersible and recyclable in any class of solvents, and the concept is illustrated with the carbon nanotubes. Classically, dispersions of CNTs can be achieved through steric stabilization induced by adsorbed or grafted polymer chains. Yet, the surface modification of CNTs surfaces is irreversible, and the chemical nature of the polymer chains imposes the range of solvents in which CNTs can be dispersed. To address this limitation, supramolecular bonds can be used to attach and to detach polymer chains from the surface of CNTs. The reversibility of supramolecular bonds offers an easy way to recycle CNTs as well as the possibility to disperse the same functional CNTs in any type of solvent, by simply adapting the chemical nature of the stabilizing chains to the dispersing medium. The concept of supramolecular functionalization can be applied to other particles, for example, silica or metal oxides, as well as to dispersing in polymer melts, films or coatings. PMID:24458908

  9. Nanotechnology with Carbon Nanotubes: Mechanics, Chemistry, and Electronics

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak

    2003-01-01

    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,

  10. Magnetic multi-walled carbon nanotubes assisted dispersive solid phase extraction of nerve agents and their markers from muddy water.

    PubMed

    Pardasani, Deepak; Kanaujia, Pankaj K; Purohit, Ajay K; Shrivastava, Anchal Roy; Dubey, D K

    2011-10-30

    The multi-walled carbon nano-tubes (MWCNT) were magnetized with iron oxide nanoparticles and were characterized by SEM and EDX analyses. These magnetized MWCNT (Mag-CNT) were used as sorbent in dispersive solid phase extraction (DSPE) mode to extract nerve agents and their markers. Mag-CNT were dispersed in water and collected with the help of an external magnet. From Mag-CNT, the adsorbed analytes were eluted and analyzed by GC-FPD in phosphorus mode. DSPE was found to be advantageous over conventional solid phase extraction (SPE) in terms of operational simplicity, speed, handling of large sample volume and recoveries. Extraction parameters such as eluting solvent, sorbent amount, pH and salinity of aqueous samples were optimized. Optimized extraction conditions included 40 mg of Mag-CNT as sorbent, chloroform as eluent, pH 3-11 and salinity 20%. Under the optimized conditions, recoveries from distilled water ranged from 60 to 96% and were comparable in tap and muddy water. Limits of quantification and limits of detection of 0.15 ng/ml and 0.05 ng/ml, respectively, were achieved. Superiority of Mag-CNT over conventional C(18) SPE was also established. PMID:22063538

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

    E-print Network

    Jensen, Grant J.

    Nonlinear 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 viscoelasticity of freestanding and polymer-anchored vertically aligned carbon nanotube foams Ludovica Lattanzi,1

  12. Helicity of Carbon Nanotubes and Helix-shaped Carbon Nanotubes

    Microsoft Academic Search

    Ji-Peng Cheng; Xiao-Bin Zhang

    2006-01-01

    Determination of the helicity of carbon nanotubes (CNTs) is useful for CNTs in nanoelectronic device applications. Using electron diffraction to measure chiral angle with a high precision is reviewed, and helix-shaped carbon nanostructures are introduced and characterized by transmission electron microscopy. The possible formation mechanism of helix-shaped CNTs is also referred in the paper

  13. Carbon Nanotube Purification

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  14. Mechanical energy storage in carbon nanotube springs

    E-print Network

    Hill, Frances Ann

    2011-01-01

    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 ...

  15. Mechanics of deformation of carbon nanotubes

    E-print Network

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

    2005-01-01

    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) ...

  16. Carbon Nanotubes Hybrid Hydrogels in Drug Delivery: A Perspective Review

    PubMed Central

    Hampel, Silke; Spizzirri, Umile Gianfranco; Parisi, Ortensia Ilaria; Picci, Nevio; Iemma, Francesca

    2014-01-01

    The use of biologics, polymers, silicon materials, carbon materials, and metals has been proposed for the preparation of innovative drug delivery devices. One of the most promising materials in this field are the carbon-nanotubes composites and hybrid materials coupling the advantages of polymers (biocompatibility and biodegradability) with those of carbon nanotubes (cellular uptake, stability, electromagnatic, and magnetic behavior). The applicability of polymer-carbon nanotubes composites in drug delivery, with particular attention to the controlled release by composites hydrogel, is being extensively investigated in the present review. PMID:24587993

  17. Terahertz transitions in quasi-metallic carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hartmann, R. R.; Portnoi, M. E.

    2015-06-01

    We study interbanddipole transitions across curvature-induced narrow gaps in quasi-metallic single-walled carbon nanotubes. The curvature effects not only open a gap in the nanotube energy spectrum but also allow optical transitions, which happen to be in the highly- desired terahertz frequency range. Applying a magnetic field along the nanotube axis allows one to tune the frequency peaks in the spectral density of absorption.

  18. A carbon nanotube needle biosensor.

    PubMed

    Yun, YeoHeung; Bange, Adam; Shanov, Vesselin N; Heineman, William R; Halsall, H Brian; Dong, Zhongyun; Jazieh, Abdul; Tu, Yi; Wong, Danny; Pixley, Sarah; Behbehani, Michael; Schulz, Mark J

    2007-07-01

    A carbon nanotube needle biosensor was developed to provide fast, cost effective and highly sensitive electrochemical detection of biomolecules. The sensor was fabricated based on an array of aligned multi-wall carbon nanotubes synthesized by chemical vapor deposition. A bundle of nanotubes in the array was welded onto the tip of a tungsten needle under a microscope. The needle was then encased in glass and a polymer coating leaving only the tip of the needle exposed. Cyclic voltammetry was performed to examine the redox behavior of the nanotube needle. The cyclic voltammetry results showed a steady-state response attributable to radial diffusion with a high steady-state current density. An amperometric sensor was then developed for glucose detection by physically attaching glucose oxidase on the nanotube needle. The amperometric response of these nanotube needles showed a high sensitivity with a low detection limit. It is expected that the nanotube needle can be sharpened to increase the sensitivity to the point where the current is almost too small to measure. The simple manufacturing method should allow commodity level production of highly sensitive electronic biosensors. PMID:17663243

  19. Dispersions of Carbon nanotubes in Polymer Matrices

    NASA Technical Reports Server (NTRS)

    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

    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.

  20. Multiscale Modeling with Carbon Nanotubes

    SciTech Connect

    Maiti, A

    2006-02-21

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

  1. Lead adsorption on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Yan-Hui; Wang, Shuguang; Wei, Jinquan; Zhang, Xianfeng; Xu, Cailu; Luan, Zhaokun; Wu, Dehai; Wei, Bingqing

    2002-05-01

    Carbon nanotubes (CTNs) show exceptional adsorption capability and high adsorption efficiency for lead removal from water. The adsorption is significantly influenced by the pH value of the solution and the nanotube surface status, which can be controlled by their treatment processing. The adsorption isotherms are well described by both Langmuir and Freundlich models. Our results suggest that CNTs can be good Pb 2+ adsorbers and have great potential applications in environmental protection.

  2. Universally dispersible carbon nanotubes.

    PubMed

    Prevoteau, Alexandre; Soulié-Ziakovic, Corinne; Leibler, Ludwik

    2012-12-12

    We show that supramolecular chemistry provides a convenient tool to prepare carbone nanotubes (CNTs) that can be dispersed in solvents of any chemical nature, easily recovered and redispersed. Thymine-modified CNTs (CNT-Thy) can be dispersed in solution in the presence of diaminotriazine (DAT) end-functionalized polymers, through supramolecular Thy/DAT association. DAT-polymer chains are selected according to the solvent chemical nature: polystyrene (PS) for hydrophobic/low polarity solvents and a propylene oxide/ethylene oxide copolymer (predominantly propylene oxide based, PPO/PEO) for polar solvents or water. Long-term stable supramolecular CNT dispersions are reversibly aggregated by adding a few droplets of a selective dissociating agent of the Thy/DAT association (DMSO). CNT-Thy, simply recycled by centrifugation or filtration, can be redispersed in another solvent in presence of a suitable soluble DAT-polymer. Dispersion and aggregation can also be switched on and off by choosing a polymer for which a given solvent is close to ?-conditions, e.g., PS in cyclohexane or PPO/PEO in water. PMID:23171241

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

    PubMed

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

    2014-08-15

    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

  4. EDITORIAL: Focus on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    2003-09-01

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

  5. Multifunctional Catalysts for Singlewall Carbon Nanotube

    E-print Network

    Guo, Ting

    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 break down various carbon species such as graphite, carbon clusters, amorphous carbon, or hydrocarbons

  6. Viscoelasticity in carbon nanotube composites.

    PubMed

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

    2005-02-01

    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 (approximately 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. PMID:15640807

  7. Effect of Carbon Nanotubes on Mammalian Cells

    NASA Astrophysics Data System (ADS)

    Chen, Michelle; Ahmed, Asma; Black, Melanie; Kawamoto, Nicole; Lucas, Jessica; Pagala, Armie; Pham, Tram; Stankiewicz, Sara; Chen, Howard

    2010-03-01

    Carbon Nanotubes possess extraordinary electrical, mechanical, and thermal properties. Research on applying the carbon nanotubes for ultrasensitive detection, disease diagnosis, and drug delivery is rapidly developing. While the fundamental and technological findings on carbon nanotubes show great promise, it is extremely important to investigate the effect of the carbon nanotubes on human health. In our experiments, we introduce purified carbon nanotubes in suspension to ovary cells cultured from Hamsters. These cells are chosen since they show robust morphological changes associated with cytotoxicity that can easily be observed under a light microscope. We will discuss the toxicity of carbon nanotubes by characterizing the cell morphology and viability as a function of time and the concentration of carbon nanotube suspension.

  8. Buckling and Collapse of Embedded Carbon Nanotubes

    Microsoft Academic Search

    O. Lourie; D. M. Cox; H. D. Wagner

    1998-01-01

    Recent experimental and theoretical results (1 - 9) sug- gest that carbon nanotubes hold great promise as a pos- sible reinforcing phase in composite materials of a new kind. Such developments still present, however, enor- mous practical challenges, especially when probing the properties of individual nanotubes (3,10- 12). The me- chanical stiffness and strength of carbon nanotubes are ex- pected

  9. Interfacial heat flow in carbon nanotube suspensions

    Microsoft Academic Search

    Scott T. Huxtable; David G. Cahill; Sergei Shenogin; Liping Xue; Rahmi Ozisik; Paul Barone; Monica Usrey; Michael S. Strano; Giles Siddons; Moonsub Shim; Pawel Keblinski

    2003-01-01

    The enormous amount of basic research into carbon nanotubes has sparked interest in the potential applications of these novel materials. One promising use of carbon nanotubes is as fillers in a composite material to improve mechanical behaviour, electrical transport and thermal transport. For composite materials with high thermal conductivity, the thermal conductance across the nanotube-matrix interface is of particular interest.

  10. Carbon Nanotube Material Quality Assessment

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  11. Carbon Nanotubes and Human Cells?

    ERIC Educational Resources Information Center

    King, G. Angela

    2005-01-01

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

  12. Carbon Nanotubes and Bucky Materials

    Microsoft Academic Search

    Mark Baxendale

    2007-01-01

    The chapter details the underlying phenomena that underpin electronic applications that have followed from the discoveries of C60 and carbon nanotubes. The reduced dimensionality of these self-organised structures, high electron mobility, weak electromigration, and the plethora of quantum electronic effects exhibited by these structures suggest they are serious candidates for molecular electronics. The detail of the surface chemistry and conditions

  13. Sugar coated stealth carbon nanotubes

    Microsoft Academic Search

    Nalinikanth Kotagiri; Jin-Woo Kim

    2010-01-01

    Single walled carbon nanotubes (SWNT) have shown tremendous promise as agents for diagnostic and therapeutic intervention in vivo. We demonstrate how Dextran sulfate (DS) can render SWNT transparent to macrophages, a vital component of the innate immunity. We also demonstrate a site specific attachment strategy to conjugate antibodies to DS for downstream applications. DS was compared to Polyethylene Glycol (PEG)

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

    PubMed

    Du, Zhuo; Liu, Miao; Li, Gongke

    2013-10-01

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

  15. Redox sorting of carbon nanotubes.

    PubMed

    Gui, Hui; Streit, Jason K; Fagan, Jeffrey A; Hight Walker, Angela R; Zhou, Chongwu; Zheng, Ming

    2015-03-11

    This work expands the redox chemistry of single-wall carbon nanotubes (SWCNTs) by investigating its role in a number of SWCNT sorting processes. Using a polyethylene glycol (PEG)/dextran (DX) aqueous two-phase system, we show that electron-transfer between redox molecules and SWCNTs triggers reorganization of the surfactant coating layer, leading to strong modulation of nanotube partition in the two phases. While the DX phase is thermodynamically more favored by an oxidized SWCNT mixture, the mildly reducing PEG phase is able to recover SWCNTs from oxidation and extract them successively from the DX phase. Remarkably, the extraction order follows SWCNT bandgap: semiconducting nanotubes of larger bandgap first, followed by semiconducting nanotubes of smaller bandgap, then nonarmchair metallic tubes of small but nonvanishing bandgap, and finally armchair metallic nanotubes of zero bandgap. Furthermore, we show that redox-induced surfactant reorganization is a common phenomenon, affecting nanotube buoyancy in a density gradient field, affinity to polymer matrices, and solubility in organic solvents. These findings establish redox modulation of surfactant coating structures as a general mechanism for tuning a diverse range of SWCNT sorting processes and demonstrate for the first time that armchair and nonarmchair metallic SWCNTs can be separated by their differential response to redox. PMID:25719939

  16. Carbon nanotubes for orthopaedic implants

    Microsoft Academic Search

    Rose L. Spear; Ruth E. Cameron

    2008-01-01

    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

  17. From carbon nanotubes to carbon atomic chains

    NASA Astrophysics Data System (ADS)

    Casillas García, Gilberto; Zhang, Weijia; José-Yacamán, Miguel

    2010-10-01

    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 TEM, two holes are opened near each other in a FLG sheet by focusing the electron beam into a small spot. Due to the radiation, the carbon atoms rearrange themselves between the two holes and form carbon fibers. The beam is concentrated on the carbon fibers in order excite the atoms and induce a tension until multi wall carbon nanotube (MWCNT) is formed. As the radiation continues the MWCNT breaks down until there is only a single wall carbon nanotube (SWCNT). Then, when the SWCNT breaks, an atomic carbon chain is formed, lasts for several seconds under the radiation and finally breaks. This demonstrates the stability of this carbon structure.

  18. Adsorption to carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kahng, Yung Ho

    We have probed the adsorption property of single-wall carbon nanotube (SWNT) bundles using the temperature-programmed desorption technique. The SWNT sample cleanliness effect on the 4He adsorption was investigated. Room air contacting significantly decreased the 4He adsorption capacity. The 4He adsorption vs. pump-out temperature on SWNT samples and on charcoal was obtained. A two-state binding site model did not fit well to the SWNT data, while it fit well to the charcoal data indicating the 4He binding energy on charcoal to be 400 +/- 32 K which agreed with other group's value. Using the desorption rate isotherm analysis technique, we obtained coverage dependant 4He binding energies on SWNT bundles. Our values agreed with other group's results at near 400 K where the coverages overlapped, and our energy value increased to a much higher value at near 900 K at lower coverages beyond the lowest coverage of other group. The 4He addition temperature was changed from 273 K to lower values in the 8--40 K range for three SWNT samples and a charcoal sample. While the 4He adsorption was not sensitive on the addition temperature on charcoal, it was different on SWNT samples. Some sites were not accessible for 4He atoms at low temperatures. The 4He access to these sites increased as the gas addition temperature increased, and at 35 K and above a full 4He access to a 273 K dosed level was observed. An activated diffusion model fit to the 4He amount, vs. gas addition temperature data yielded the activation energy for diffusion to be 28 +/- 14 K and 47 +/- 6 K on two samples. One sample showed more restricted 4He access for 4He at 15 K. This sample had more impurities. Codesorption measurements were done on SWNT samples. Xe in smaller quantity (6% level) than 4He and H2, suppressed the adsorption of other gases to the background level. H2 suppressed 4 He to the background level, when added in equal amount at 273 K. However when 4He was added at 273 K and H2 was added later at 19 K, H2 did not suppress the 4He adsorption. Equal mixture doses of 4He and 3He at 273 K yielded 8.4 times more 4He binding than 3He. This strong isotope selectivity agreed with the predicted quantum sieving effect.

  19. Peel test of spinnable carbon nanotube webs

    NASA Astrophysics Data System (ADS)

    Khandoker, Noman; Hawkins, Stephen C.; Ibrahim, Raafat; Huynh, Chi P.

    2014-06-01

    This paper presents results of peel tests with spinnable carbon nanotube webs. Peel tests were performed to study the effect of orientation angles on interface energies between nanotubes. In absence of any binding agent the interface energy represents the Van Der Waals energies between the interacting nanotubes. Therefore, the effect of the orientations on Van Der Waals energies between carbon nanotubes is obtained through the peel test. It is shown that the energy for crossed nanotubes at 90° angle is lower than the energy for parallel nanotubes at 0° angle. This experimental observation was validated by hypothetical theoretical calculations.

  20. Carbon nanotubes by the metallocene route

    NASA Astrophysics Data System (ADS)

    Sen, Rahul; Govindaraj, A.; Rao, C. N. R.

    1997-03-01

    Pyrolysis of metallocenes such as ferrocene, cobaltocene and nickelocene, is shown to yield carbon nanotubes and metal-filled onion-like structures. Pyrolysis of benzene in the presence of a metallocene gives high yields of nanotubes, the wall thickness of the nanotubes depending on the metallocene content. Pyrolysis of benzene in the absence of any metal however gives monodispersed nanospheres of carbon rather than nanotubes.

  1. Elastic and mechanical properties of carbon nanotubes

    Microsoft Academic Search

    C. Goze; L. Vaccarini; L. Henrard; P. Bernier; E. Hemandez; A. Rubio

    1999-01-01

    We present a comparative study of energetic, structural and elastic properties of carbon and composite single wall nanotubes using a non-orthogonal tight binding formalism. We investigate Young Modulus and Poisson ratio of (n,0) and (n,n) nanotubes, with n=(520). Our calculations predict that carbon nanotubes have a higher Young Modulus (1TPa) than any of the studied composite nanotubes and of the

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

    PubMed

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

    2014-06-01

    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

  3. Electronic focusing in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Häberle, Patricio; Hevia, Samuel; Segura, Rodrigo

    2010-03-01

    Slow electrons traveling close to a surface exhibit modifications of their trajectories due to the polarization charge they induce on the surface. This image charge interaction, in the case of carbon nanotubes (CNTs), is responsible for focusing electrons traveling in the vicinity of a nanotube. The consequences of this effect on the electronic trajectories are more significant for both low kinetic energies and small tube diameters. Numerical calculations indicate low energy electron spectroscopies are especially sensitive to this phenomenon. We have observed evidence of this electronic focusing in inverse photoemission spectroscopy from different CNTs samples.

  4. Dust acoustic wave oscillations in metallic carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Fathalian, Ali; Nikjo, Shahram

    2010-06-01

    We present theoretical analysis of plasmon dispersion in single-walled metallic carbon nanotubes (SWCNTs) in the presence of low-frequency electromagnetic radiation, based on classical electrodynamic formulations and linearized hydrodynamic model. We assume that metallic carbon nanotubes (CNTs) are charged due to the field emission, and hence the metallic nanotubes can be regarded as charged dust rods surrounded by degenerate electrons and ions. Calculations are performed for the transverse electric (TE) and transverse magnetic (TM) waves, respectively, by solving the Maxwell and hydrodynamic equations with appropriate boundary conditions.

  5. Carbon-Nanotube Schottky Diodes

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  6. Nondestructive Evaluation Techniques for Development and Characterization of Carbon Nanotube Based Superstructures

    NASA Technical Reports Server (NTRS)

    Wincheski, Buzz; Kim, Jae-Woo; Sauti, Godfrey; Wainwright, Elliot; Williams, Phillip; Siochi, Emile J.

    2014-01-01

    Recently, multiple commercial vendors have developed capability for the production of large-scale quantities of high-quality carbon nanotube sheets and yarns. While the materials have found use in electrical shielding applications, development of structural systems composed of a high volume fraction of carbon nanotubes is still lacking. A recent NASA program seeks to address this by prototyping a structural nanotube composite with strength-toweight ratio exceeding current state-of-the-art carbon fiber composites. Commercially available carbon nanotube sheets, tapes, and yarns are being processed into high volume fraction carbon nanotube-polymer nanocomposites. Nondestructive evaluation techniques have been applied throughout this development effort for material characterization and process control. This paper will report on the progress of these efforts, including magnetic characterization of residual catalyst content, Raman scattering characterization of nanotube diameter, defect ratio, and nanotube strain, and polarized Raman scattering for characterization of nanotube alignment.

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

    Microsoft Academic Search

    Ignác Capek

    2009-01-01

    Nanomaterials are structures with dimensions characteristically much below 100 nm. The unique physical properties (e.g., conductivity, reactivity) have placed these nanomaterials in the forefront of emerging technologies. Significant enhancement of optical, mechanical, electrical, structural, and magnetic properties are commonly found through the use of novel nanomaterials. One of the most exciting classes of nanomaterials is represented by the carbon nanotubes. Carbon

  8. Impact of tube curvature on the ground-state magnetism of axially confined single-walled carbon nanotubes of the zigzag-type.

    PubMed

    Wu, Jianhua; Hagelberg, Frank

    2013-06-01

    The magnetic properties of axially confined, hydrogenated single-walled carbon nanotubes (SWCNTs) of the (n,0)-type with n=5-24 are systematically explored by density functional theory. Emphasis is placed on the relation between the ground-state magnetic moments of SWCNTs and zigzag graphene nanoribbons (ZGNRs). Comparison between the SWCNTs considered here and ZGNRs of equal length gives rise to two basic questions: 1) how does the nanotube curvature affect the antiferromagnetic order known to prevail for ZGNRs, and 2) to what extent do the magnetic moments localized at the SWCNT edges deviate from the zero-curvature limit of n/3?B ? In response to these questions, it is found that systems with n?7 display preference for antiferromagnetic order at any length investigated, whereas for n=5, 6 the magnetic phase varies with tube length. Furthermore, elementary patterns are identified that describe the progression of the magnitude of the magnetic moment with n for the longest tubes explored in this work. The spin densities of the considered SWCNTs are analyzed as a function of the tube length L, with L ranging from 3 to 11 transpolyene rings for n?7 and from 3 to 30 rings for n=5 and 6. PMID:23589448

  9. Magnetic sensitivity of a dispersion of aggregated ferromagnetic carbon nanotubes in liquid crystals

    E-print Network

    Reznikov, Yuri

    is efficiently controlled by weak electric fields. Since the phase retardation of light in a LC cell critically field. The magnetic field realigns the aggregates of the particles which results in a non expand with the increase of the magnetic field and achieve maximum size of several micrometres

  10. Twisting Graphene into Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    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)

  11. Designing an optimum pulsed magnetic field by a resistance/self-inductance/capacitance discharge system and alignment of carbon nanotubes embedded in polypyrrole matrix

    NASA Astrophysics Data System (ADS)

    Kazemikia, Kaveh; Bonabi, Fahimeh; Asadpoorchallo, Ali; Shokrzadeh, Majid

    2015-02-01

    In this work, an optimized pulsed magnetic field production apparatus is designed based on a RLC (Resistance/Self-inductance/Capacitance) discharge circuit. An algorithm for designing an optimum magnetic coil is presented. The coil is designed to work at room temperature. With a minor physical reinforcement, the magnetic flux density can be set up to 12 Tesla with 2 ms duration time. In our design process, the magnitude and the length of the magnetic pulse are the desired parameters. The magnetic field magnitude in the RLC circuit is maximized on the basis of the optimal design of the coil. The variables which are used in the optimization process are wire diameter and the number of coil layers. The coil design ensures the critically damped response of the RLC circuit. The electrical, mechanical, and thermal constraints are applied to the design process. A locus of probable magnetic flux density values versus wire diameter and coil layer is provided to locate the optimum coil parameters. Another locus of magnetic flux density values versus capacitance and initial voltage of the RLC circuit is extracted to locate the optimum circuit parameters. Finally, the application of high magnetic fields on carbon nanotube-PolyPyrrole (CNT-PPy) nano-composite is presented. Scanning probe microscopy technique is used to observe the orientation of CNTs after exposure to a magnetic field. The result shows alignment of CNTs in a 10.3 Tesla, 1.5 ms magnetic pulse.

  12. Trapping Cold Atoms by a Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Chu, T. A.; Nga, D. T.; Thao, T. T.; Ngo, V. Thanh; Viet, N. A.

    A new model of cold atoms trap using a carbon nanotube is proposed. In this model, for the existence of a stable bound state of cold atom, we send a strong electromagnetic field through the carbon nanotube. This field generates an evanescent wave around the carbon nanotube and creates an effective attractive potential. The consideration of some possible boundary conditions leads to this non-trivial bound state solution. We compare also our result to the two most recent models concerning trapping of cold atoms by using a charged carbon nanotube and an optical fiber.

  13. Multilayer Film Assembly of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    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.

  14. Alignment of Carbon Nanotubes Comprising Magnetically Sensitive Metal Oxides in Nanofluids

    NASA Technical Reports Server (NTRS)

    Hong, Haiping (Inventor); Peterson, G. P. 'Bud' (Inventor)

    2014-01-01

    The present invention is a nanoparticle mixture or suspension or nanofluid comprising nonmagnetically sensitive nanoparticles, magnetically sensitive nanoparticles, and surfactant(s). The present invention also relates to methods of preparing and using the same.

  15. Torsional Carbon Nanotube Artificial Muscles

    NASA Astrophysics Data System (ADS)

    Foroughi, Javad; Spinks, Geoffrey M.; Wallace, Gordon G.; Oh, Jiyoung; Kozlov, Mikhail E.; Fang, Shaoli; Mirfakhrai, Tissaphern; Madden, John D. W.; Shin, Min Kyoon; Kim, Seon Jeong; Baughman, Ray H.

    2011-10-01

    Rotary motors of conventional design can be rather complex and are therefore difficult to miniaturize; previous carbon nanotube artificial muscles provide contraction and bending, but not rotation. We show that an electrolyte-filled twist-spun carbon nanotube yarn, much thinner than a human hair, functions as a torsional artificial muscle in a simple three-electrode electrochemical system, providing a reversible 15,000° rotation and 590 revolutions per minute. A hydrostatic actuation mechanism, as seen in muscular hydrostats in nature, explains the simultaneous occurrence of lengthwise contraction and torsional rotation during the yarn volume increase caused by electrochemical double-layer charge injection. The use of a torsional yarn muscle as a mixer for a fluidic chip is demonstrated.

  16. Torsional electromechanical quantum oscillations in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cohen-Karni, Tzahi; Segev, Lior; Srur-Lavi, Onit; Cohen, Sidney R.; Joselevich, Ernesto

    2006-10-01

    Carbon nanotubes can be distinctly metallic or semiconducting depending on their diameter and chirality. Here we show that continuously varying the chirality by mechanical torsion can induce conductance oscillations, which can be attributed to metal-semiconductor periodic transitions. The phenomenon is observed in multiwalled carbon nanotubes, where both the torque and the current are shown to be carried predominantly by the outermost wall. The oscillation period with torsion is consistent with the theoretical shifting of the corners of the first Brillouin zone of graphene across different sub-bands allowed in the nanotube. Beyond a critical torsion, the conductance irreversibly drops due to torsional failure, allowing us to determine the torsional strength of carbon nanotubes. Carbon nanotubes could be ideal torsional springs for nanoscopic pendulums, because electromechanical detection of motion could replace the microscopic detection techniques used at present. Our experiments indicate that carbon nanotubes could be used as electronic sensors of torsional motion in nanoelectromechanical systems.

  17. Polyethylene multiwalled carbon nanotube composites

    Microsoft Academic Search

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

    2005-01-01

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

  18. Polyethylene glycol modified magnetic carbon nanotubes as nanosorbents for the determination of methylprednisolone in rat plasma by high performance liquid chromatography.

    PubMed

    Yu, Panfeng; Ma, Hongwei; Shang, Yong; Wu, Ji; Shen, Shun

    2014-06-27

    In this paper, polyethylene glycol modified (PEGylated) magnetic carbon nanotubes were developed as solid-phase extraction nanosorbents for the determination of methylprednisolone in rat plasma. The procedure mainly involved two steps including preparation of PEGylated magnetic nanosorbents and bioanalysis. Monodisperse magnetites (Fe3O4) anchored onto multi-walled carbon nanotubes (MWCNTs) were synthesized by a facile solvothermal synthesis method. The obtained MWCNTs-Fe3O4 nanomaterials were further non-covalently functionalized by a surfactant phospholipids-polyethylene glycol (DSPE-PEG). Owing to dispersibility and high enrichment ability, water-soluble PEGylated MWCNTs-Fe3O4 nanomaterials can provide more efficient way for the extraction of methylprednisolone than only MWCNTs-Fe3O4 used. The methylprednisolone could be easily extracted via ?-? stacking interactions with PEGylated MWCNTs-Fe3O4. The captured methylprednisolone/nanosorbents were isolated from the matrix by placing a magnet, and desorbed by the elution solvent composed of acetonitrile. Extraction conditions such as amount of nanosorbents added, adsorption time, desorption solvent, and desorption time were investigated and optimized. The method recoveries were obtained from 88.2% to 92.9%. Limits of quantification and limits of detection of 0.01 and 0.005?g/mL were acquired, respectively. The precision ranged from 4.2% to 7.8% for within-day measurement, and for between-day variation was in the range of 5.5-9.0%. Moreover, the analytical performance obtained by PEGylated magnetic MWCNTs was compared with that of magnetic MWCNTs. The results indicated that the approach based on PEGylated magnetic MWCNTs was useful for the analysis of methylprednisolone in the complex plasma. PMID:24837418

  19. Double-Wall Carbon Nanotubes

    Microsoft Academic Search

    Rudolf Pfeiffer; Thomas Pichler; Yoong Kim; Hans Kuzmany

    \\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

  20. Lipid Bilayers Covalently Anchored to Carbon Nanotubes

    PubMed Central

    Dayani, Yasaman; Malmstadt, Noah

    2012-01-01

    The unique physical and electrical properties of carbon nanotubes make them an exciting material for applications in various fields such as bioelectronics and biosensing. Due to the poor water solubility of carbon nanotubes, functionalization for such applications has been a challenge. Of particular need are functionalization methods for integrating carbon nanotubes with biomolecules and constructing novel hybrid nanostructures for bionanoelectronic applications. We present a novel method for the fabrication of dispersible, biocompatible carbon nanotube-based materials. Multi-walled carbon nanotubes (MWCNTs) are covalently modified with primary amine-bearing phospholipids in a carbodiimide-activated reaction. These modified carbon nanotubes have good dispersibility in nonpolar solvents. Fourier transform infrared (FTIR) spectroscopy shows peaks attributable to the formation of amide bonds between lipids and the nanotube surface. Simple sonication of lipid-modified nanotubes with other lipid molecules leads to the formation of a uniform lipid bilayer coating the nanotubes. These bilayer-coated nanotubes are highly dispersible and stable in aqueous solution. Confocal fluorescence microscopy shows labeled lipids on the surface of bilayer-modified nanotubes. Transmission electron microscopy (TEM) shows the morphology of dispersed bilayer-coated MWCNTs. Fluorescence quenching of lipid-coated MWCNTs confirms the bilayer configuration of the lipids on the nanotube surface and fluorescence anisotropy measurements show that the bilayer is fluid above the gel-to-liquid transition temperature. The membrane protein ?-hemolysin spontaneously inserts into the MWCNT-supported bilayer, confirming the biomimetic membrane structure. These biomimetic nanostructures are a promising platform for the integration of carbon nanotube-based materials with biomolecules. PMID:22568448

  1. Magnetic single-walled carbon nanotubes-dispersive solid-phase extraction method combined with liquid chromatography-tandem mass spectrometry for the determination of paraquat in urine.

    PubMed

    Ruan, Xiao-Lin; Qiu, Jing-Jing; Wu, Chuan; Huang, Tao; Meng, Rui-Bo; Lai, Yong-Qiang

    2014-08-15

    In this study, magnetic single-walled carbon nanotubes (MSWCNTs) were prepared by impregnating magnetic Fe3O4 nanoparticles onto the surfaces of carboxylic single-walled carbon nanotubes based on electrostatic interactions. The prepared MSWCNTs were used as the adsorbent for the dispersive solid-phase extraction (DSPE) of paraquat from human urine. After adsorption, the paraquat was quantitatively desorbed with 5%TFA in acetonitrile and determined by HPLC-MS. Extraction parameters such as the type of CNT adsorbent, extraction time, sample volume, wash solvent, and the type and volume of desorption solvent were optimized to obtain high DSPE recoveries and extraction efficiencies. Under the optimized conditions, the calibration curve was linear in the range 3.75-375.0 ?g/L with a correlation coefficient of 0.999 45. The LOD (S/N=3) and LOQ (S/N=10) were 0.94 and 2.82 ?g/L, respectively. The recoveries ranged from 92.89 to 108.9% for spiked real urine samples with RSDs below 3.21%. Finally, the new method was successfully used to determine paraquat in urine samples of suspected paraquat poisoning patients. The MSWCNTs exhibited suitable properties and a high adsorption capacity for the extraction of paraquat. PMID:24999616

  2. ccsd00003923, Combination of carbon nanotubes and

    E-print Network

    ccsd­00003923, version 1 ­ 18 Jan 2005 Combination of carbon nanotubes and two-photon absorbers-linear scattering from single-wall carbon nanotubes (SWNT) and multiphoton absorption (MPA) from organic and are particularly e�cient in the nanosecond regime due to cumulative e#11;ects. 1 Introduction Active eye and sensor

  3. Transport-limited emission from carbon nanotubes

    Microsoft Academic Search

    J. L. Shaw; D. S. Y. Hsu

    2001-01-01

    We have recently demonstrated emission from arrays of gated multiwall carbon nanotubes on silicon substrates. In addition to fabrication development, these structures are useful for study of the carbon nanotube emission properties. To that end, we have measured the effect of emission current, temperature, and gas environments on the energy distributions. We find that the emission near the Fermi level

  4. Functionalized carbon nanotube nanoelectrodes for biomolecular recognition

    Microsoft Academic Search

    Narasimha Harindra Vedala

    2009-01-01

    The objective of this research is to develop nanoscale ultrasensitive transducers for detection of biological species at molecular level using carbon nanotubes as nanoelectrodes. Rapid detection of ultra low concentration or even single DNA molecules are essential for medical diagnosis and treatment, pharmaceutical applications, gene sequencing as well as forensic analysis. Here the use of functionalized single walled carbon nanotubes

  5. Analysis of Silicon Carbide Coated Carbon Nanotubes

    Microsoft Academic Search

    Adam Konneker; Jun Song; Ricky Wyman; Richard Vanfleet; David Allred; Robert Davis

    2009-01-01

    The purpose of this research is to explore the use of silicon carbide coated carbon nanotubes in microelectromechanical systems or MEMS. In our research group at Brigham Young University, we are developing a method of MEMS fabrication through the use of carbon nanotube (abbreviated CNT) ``scaffolds.'' Traditional MEMS fabrication techniques are use chemical etching to create three dimensional structures. Our

  6. Catalytic Routes Towards Single Wall Carbon Nanotubes

    Microsoft Academic Search

    Emmanuel Lamouroux; Philippe Serp; Philippe Kalck

    2007-01-01

    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

  7. Faster and Smaller with Carbon Nanotubes?

    Microsoft Academic Search

    Robert V. Seidel; Andrew P. Graham; Georg S. Duesberg; Maik Liebau; Eugen Unger; Franz Kreupl; Wolfgang Hoenlein

    Carbon Nanotubes seem to be one of the most promising candidates for nanoelectronic devices beyond presumable scaling limits of silicon and compound semiconductors and independent from lithographic limitations. Discovered only about a decade ago, there has been a tremendous advance in the field of carbon nanotubes. Their exciting properties, especially with respect to electronic applications, and their fabrication methods will

  8. Imaging carbon nanotubes by scanning electron microscopy

    Microsoft Academic Search

    Dmitriy Dikin

    2005-01-01

    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

  9. Longitudinal solitons in carbon nanotubes

    SciTech Connect

    Astakhova, T. Yu.; Gurin, O. D.; Menon, M.; Vinogradov, G. A.

    2001-07-15

    We present results on soliton excitations in carbon nanotubes (CNT's) using Brenner's many-body potential. Our numerical simulations demonstrate high soliton stability in (10,10) CNT's. The interactions of solitons and solitary excitation with CNT defect are found to be inelastic if the excitations and defects length scales are comparable, resulting in a substantial part of soliton energy being distributed inhomogeneously over the defect bonds. In these solitary-excitation--cap collisions the local energy of a few bonds in the cap can exceed the average energy by an order of magnitude and more. This phenomenon, denoted the ''Tsunami effect,'' can contribute dynamically to the recently proposed ''kinky chemistry.'' We also present results of changes in the local density of states and variations in the atomic partial charges estimated at different time instants of the solitary-excitation Tsunami at the nanotube cap.

  10. Vibrating Suspended Carbon Nanotube Josephson Junctions

    NASA Astrophysics Data System (ADS)

    Keijzers, C. J. H.; Padurariu, C.; Nazarov, Y. V.; Kouwenhoven, L. P.

    2012-02-01

    We study a Josephson junction with an embedded high-frequency and high-quality mechanical resonator, made from a suspended carbon nanotube. Good transparency of the superconductor-nanotube interface allows for the observation of supercurrent through the suspended nanotube, owing to the Josephson effect. The magnitude of the supercurrent is dependent on the charge on the nanotube and can be periodically modulated by a gate electrode, similar to previously reported experiments in unsuspended carbon nanotube Josephson junctions. In such a device we find a 1GHz mechanical resonance frequency and a Q factor of 500000. In the regime where the AC Josephson current and charge oscillations induced by the nanotube motion are resonant, we observe a signal of the mechanical resonator, that can be contributed to the interplay of Josephson dynamics and mechanical dynamics. Our work is motivated by the search for a new and sensitive vibration detector, ultimately to measure the ground state motion of the nanotube resonator.

  11. Filling and chemical modification of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Naguib, Nevin N.

    In order to utilize carbon nanotubes in nanofluidic device applications as well as nanocomposite reinforcement, more research on filling, surface chemistry and interaction of carbon nanotubes with liquids must be done. Understanding the penetration of fluids into nanochannels is important for the efficient storage of liquids as well as composite manufacturing. Transmission electron microscopy, Infrared spectroscopy, mass spectroscopy have been used in this research as the main investigation tools. In this research, an autoclave high temperature-high pressure system was built. Carbon nanotubes were shown to be successfully filled by using this autoclave treatment. The conditions have been determined for the filling of different types of carbon nanotubes and carbon nanofibers of different diameters with water and ethylene glycol. Water has been demonstrated and confirmed to be trapped inside heat-treated carbon nanofibers of 50--200 nm in diameter, chemical vapor deposited nanotubes of 2.5--5 nm in diameter, and possibly double wall carbon nanotubes and single wall carbon nanotubes with diameters of 1.5--2 nm. At the scale of 5 nm or less, water molecules were observed in-situ below the continuum limit, where they were shown to form clusters and chains. The effect of diameter on water filling of chemical vapor deposited nanotubes is observed. These tubes have a much less filling yield (15%) compared to heat-treated carbon nanofibers, which have a 30% filling yield. Optimum conditions of water filling have been determined to be at 650°C and 80 MPa for most nanotubes studied in this research. Conversely, when ethylene glycol was mixed and treated with carbon nanotubes by autoclave conditions, it tends to polymerize and possibly form a polyester outside and inside of the nanotubes. Besides studying the filling of carbon nanotubes with water and ethylene glycol, careful investigation of surface structure of different types of carbon nanotubes have been performed. Hydrothermal nanotubes are shown to have hydrophilic surfaces with at least carboxyl and hydroxyl groups existing. Heat-treated carbon nanofibers are shown to be hydrophobic because of formation of loops on the surface during heat treatment, while pyrolytically stripped carbon nanofibers are partially hydrophilic because of the presence of dangling bonds formed during oxidation.

  12. Glucose oxidase immobilization onto carbon nanotube networking

    E-print Network

    Karachevtsev, V A; Zarudnev, E S; Karachevtsev, M V; Leontiev, V S; Linnik, A S; Lytvyn, O S; Plokhotnichenko, A M; Stepanian, S G

    2012-01-01

    When elaborating the biosensor based on single-walled carbon nanotubes (SWNTs), it is necessary to solve such an important problem as the immobilization of a target biomolecule on the nanotube surface. In this work, the enzyme (glucose oxidase (GOX)) was immobilized on the surface of a nanotube network, which was created by the deposition of nanotubes from their solution in 1,2-dichlorobenzene by the spray method. 1-Pyrenebutanoic acid succinimide ester (PSE) was used to form the molecular interface, the bifunctional molecule of which provides the covalent binding with the enzyme shell, and its other part (pyrene) is adsorbed onto the nanotube surface. First, the usage of such a molecular interface leaves out the direct adsorption of the enzyme (in this case, its activity decreases) onto the nanotube surface, and, second, it ensures the enzyme localization near the nanotube. The comparison of the resonance Raman (RR) spectrum of pristine nanotubes with their spectrum in the PSE environment evidences the creat...

  13. Carbon nanotube initiated formation of carbon nanoscrolls Zhao Zhang1

    E-print Network

    Li, Teng

    graphene on a substrate, initiated by a carbon nanotube CNT . The rolling of graphene into a CNS, combining with the exceptional mechanical and electronic properties inherited from the basal graphene,6Carbon nanotube initiated formation of carbon nanoscrolls Zhao Zhang1 and Teng Li1,2,a 1 Department

  14. Highly stable magnetic multiwalled carbon nanotube composites for solid-phase extraction of linear alkylbenzene sulfonates in environmental water samples prior to high-performance liquid chromatography analysis.

    PubMed

    Chen, Bo; Wang, Sha; Zhang, Qianmao; Huang, Yuming

    2012-03-01

    The magnetic multiwalled carbon nanotubes (MMWCNTs) have been successfully prepared using a one-pot chemical coprecipitation method, in which magnetic nanoparticles (MNPs) were deposited onto multiwalled carbon nanotubes (MWCNTs) by in situ high temperature decomposition of the magnetic precursor of iron(III) in ethylene glycol media. A novel procedure for extraction of linear alkylbenzene sulfonates (LAS) as a model compound was thus developed in an off-line extraction system with detection by HPLC. The procedure includes the separation and preconcentration of LAS homologues onto MMWCNTs at pH 7.0 and their subsequent detection after sonication elution, followed by the separation of the MMWCNTs from the aqueous phase by external magnetic field and washing with ultra pure water. With a sample volume of 500 mL and 100 mg MMWCNTs sorbents, an enrichment factor of about 500, and a detection limit of 0.013-0.021 ?g L(-1) were obtained within a linear range of 0.5-100 ?g L(-1), together with a correlation coefficient of 0.9938-0.9998 for four LAS homologues. A precision of 2.4-5.6% was obtained for six replicate determinations of 50 ?g L(-1) LAS. The recoveries of LAS homologues spiked in environmental water samples ranged from 87.3 to 106.3%, demonstrating the utility of the MMWCNTs adsorbents in a series of water samples. Stability testing demonstrated that the MMWCNTs remained 95.0% recovery for the target LAS even after a run of 50 adsorption and desorption cycles, showing their super operational stability. The MMWCNTs are promising adsorbents, suitable for the long-term repetitive sorption/desorption of target compounds in environmental water samples. PMID:22262090

  15. Computational aspects of carbon and boron nanotubes.

    PubMed

    Manuel, Paul

    2010-01-01

    Carbon hexagonal nanotubes, boron triangular nanotubes and boron a-nanotubes are a few popular nano structures. Computational researchers look at these structures as graphs where each atom is a node and an atomic bond is an edge. While researchers are discussing the differences among the three nanotubes, we identify the topological and structural similarities among them. We show that the three nanotubes have the same maximum independent set and their matching ratios are independent of the number of columns. In addition, we illustrate that they also have similar underlying broadcasting spanning tree and identical communication behavior. PMID:21119566

  16. Strongly correlated electron behavior in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Marc, Bockrath; Deshpande, Vikram V.; Chandra, Bhupesh; Caldwell, Robert; Novikov, Dmitry S.; Hone, James

    2012-03-01

    One dimensional systems offer a fascinating platform for investigating and understanding the collective and many-body behavior of interacting electron systems. We report low-temperature transport experiments on carbon nanotubes, which are archetypal one-dimensional systems that have either semiconducting or metallic band structure depending on their radius and chirality. Semiconducting nanotubes at low densities exhibit Wigner crystal behavior, while nominally metallic nanotubes are observed to have an energy gap at half filling, consistent with theories of a Mott insulating state in nanotubes. Our results demonstrate nanotubes' promise for studying a variety of tunable correlated electron phenomena in one dimension.

  17. Epitaxial Approaches to Carbon Nanotube Organization

    NASA Astrophysics Data System (ADS)

    Ismach, Ariel

    Carbon nanotubes have unique electronic, mechanical, optical and thermal properties, which make them ideal candidates as building blocks in nano-electronic and electromechanical systems. However, their organization into well-defined geometries and arrays on surfaces remains a critical challenge for their integration into functional nanosystems. In my PhD, we developed a new approach for the organization of carbon nanotubes directed by crystal surfaces. The principle relies on the guided growth of single-wall carbon nanotubes (SWNTs) by atomic features presented on anisotropic substrates. We identified three different modes of surface-directed growth (or 'nanotube epitaxy'), in which the growth of carbon nanotubes is directed by crystal substrates: We first observed the nanotube unidirectional growth along atomic steps ('ledge-directed epitaxy') and nanofacets ('graphoepitaxy') on the surface of miscut C-plane sapphire and quartz. The orientation along crystallographic directions ('lattice-directed epitaxy') was subsequently observed by other groups on different crystals. We have proposed a "wake growth" mechanism for the nanotube alignment along atomic steps and nanofacets. In this mechanism, the catalyst nanoparticle slides along the step or facet, leaving the nanotube behind as a wake. In addition, we showed that the combination of surface-directed growth with external forces, such as electric-field and gas flow, can lead to the simultaneous formation of complex nanotube structures, such as grids and serpentines. The "wake growth" model, which explained the growth of aligned nanotubes, could not explain the formation of nanotube serpentines. For the latter, we proposed a "falling spaghetti" mechanism, in which the nanotube first grows by a free-standing process, aligned in the direction of the gas flow, then followed by absorption on the stepped surface in an oscillatory manner, due to the competition between the drag force caused by the gas flow on the suspended nanotube and the anisotropic interaction between the stepped surface and the nanotube. We characterized the nanotubes by SEM, AFM, HRTEM, EFM and transport measurements. In addition, the nanotubes were characterized by Raman spectroscopy (in collaboration with scientists from MIT, UFMG-Brazil and Rochester University). This research showed for the first time the organization of nanotubes into well-defined structures including straight, wavy, kinked, crossbar architectures, serpentines and coils. Furthermore, epitaxial carbon nanotubes show very good conductances and low density of structural defects. All these results make the 'nanotube epitaxy' approach very promising for the study, organization and integration of one-dimensional materials into functional nanosystems.

  18. Theoretical analysis of the Faraday effect in zigzag carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zarifi, Abbas; Pedersen, Thomas Garm

    2008-02-01

    The optical properties of zigzag carbon nanotubes in magnetic fields are analyzed. Using a tight-binding model with nearest-neighbor interactions, general expressions are computed for the diagonal and off-diagonal elements of the frequency dependent susceptibility in the presence of an axial magnetic field. The off-diagonal elements are applied to calculate the interband Faraday rotation and the Verdet constant. We predict that these effects should be clearly detectable under realistic conditions using weak magnetic fields.

  19. Carbon nanotube growth density control

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  20. Electron emission properties of carbon nanotubes

    NASA Astrophysics Data System (ADS)

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

    2001-01-01

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

  1. Alignment Dynamics of Single-Walled Carbon Nanotubes in Pulsed Ultrahigh

    E-print Network

    Kono, Junichiro

    ), rolled up tubes of graphene sheets, are unique nano-objects with extreme aspect ratios, which leadAlignment Dynamics of Single-Walled Carbon Nanotubes in Pulsed Ultrahigh Magnetic Fields Jonah and CNRS, 351 cours de la Libe´ration, Talence, F-33405, France. S ingle-walled carbon nanotubes (SWNTs

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

    PubMed

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

    2014-12-10

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

  3. Conceptual design of carbon nanotube processes

    Microsoft Academic Search

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

    2007-01-01

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

  4. Twisting graphene nanoribbons into carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kit, O. O.; Tallinen, T.; Mahadevan, L.; Timonen, J.; Koskinen, P.

    2012-02-01

    Although carbon nanotubes consist of honeycomb carbon, they have never been fabricated from graphene directly. Here, it is shown by quantum molecular-dynamics simulations and classical continuum-elasticity modeling, that graphene nanoribbons can, indeed, be transformed into carbon nanotubes by means of twisting. The chiralities of the tubes thus fabricated can be not only predicted but also externally controlled. This twisting route is an opportunity for nanofabrication, and is easily generalizable to ribbons made of other planar nanomaterials.

  5. Development of Carbon-Nanotube/Polymer Composites

    NASA Technical Reports Server (NTRS)

    Reynolds, Thomas A.

    2005-01-01

    A report presents a short discussion of one company's effort to develop composites of carbon nanotubes in epoxy and other polymer matrices. The focus of the discussion is on the desirability of chemically modifying carbon nanotubes to overcome their inherent chemical nonreactivity and thereby enable the formation of strong chemical bonds between nanotubes and epoxies (or other polymeric matrix materials or their monomeric precursors). The chemical modification is effected in a process in which discrete functional groups are covalently attached to the nanotube surfaces. The functionalization process was proposed by the company and demonstrated in practice for the first time during this development effort. The covalently attached functional groups are capable of reacting with the epoxy or other matrix resin to form covalent bonds. Furthermore, the company uses this process to chemically modify the nanotube surfaces, affording tunable adhesion to polymers and solubility in select solvents. Flat-sheet composites containing functionalized nanotubes demonstrate significantly improved mechanical, thermal, and electrical properties.

  6. Synthesis and properties of filled carbon nanotubes

    Microsoft Academic Search

    A. Leonhardt; M. Ritschel; R. Kozhuharova; A. Graff; T. Mühl; R. Huhle; I. Mönch; D. Elefant; C. M. Schneider

    2003-01-01

    Single- and multi-walled carbon nanotubes are very interesting nanoscaled materials with many possible applications in nanoelectronics. Especially, nanotubes filled with ferromagnetic materials (Fe, Co, Ni) may have significant potential in data storage. Such structures may help to exceed the best available storage densities (>65 Gb\\/inch2) and show in the case of Fe-filled nanotubes higher coercivities compared to bulk Fe. In

  7. Ballistic carbon nanotube field-effect transistors

    Microsoft Academic Search

    Ali Javey; Jing Guo; Qian Wang; Mark Lundstrom; Hongjie Dai

    2003-01-01

    A common feature of the single-walled carbon-nanotube field-effect transistors fabricated to date has been the presence of a Schottky barrier at the nanotube-metal junctions. These energy barriers severely limit transistor conductance in the `ON' state, and reduce the current delivery capability-a key determinant of device performance. Here we show that contacting semiconducting single-walled nanotubes by palladium, a noble metal with

  8. Synthesis and characterization of multiwalled carbon nanotube/FeCo nanocomposites.

    PubMed

    Falqui, Andrea; Loche, Danilo; Casula, Maria F; Corrias, Anna; Gozzi, Daniele; Latini, Alessandro

    2011-03-01

    Multiwalled carbon nanotube/FeCo nanocomposites were produced by Catalytic Chemical Vapour Deposition using highly porous FeCo-SiO2 aerogels with different loadings and dimensions of FeCo nanoparticles as catalysts. Multiwalled carbon nanotubes with average number of walls depending on the size of the catalyst nanoparticles were obtained. Inside the nanotubes spherical or elliptical FeCo nanoparticles are retained, and the magnetic properties of the resulting nanocomposites were characterized in detail. PMID:21449371

  9. Pyrolytic carbon nanotubes from vapor-grown carbon fibers

    Microsoft Academic Search

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

    1995-01-01

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

  10. Microcapsule carbon nanotube devices for therapeutic applications

    NASA Astrophysics Data System (ADS)

    Kulamarva, Arun; Raja, Pavan M. V.; Bhathena, Jasmine; Chen, Hongmei; Talapatra, Saikat; Ajayan, Pulickel M.; Nalamasu, Omkaram; Prakash, Satya

    2009-01-01

    Carbon nanotubes are a new class of nanomaterials that have immense potential in the field of biomedicine. Their ability to carry large quantities of therapeutic molecules makes them prime candidates for providing targeted delivery of therapeutics for use in various diseases. However, their utility is limited due to the problems faced during their delivery to target sites. This article for the first time describes the design of a novel microcapsule carbon nanotube targeted delivery device. This device has potential in the targeted delivery of carbon nanotubes in suitable membranes along with their cargo, safely and effectively to the target loci.

  11. Testing and characterization of carbon nanotubes as strain sensors

    E-print Network

    Diaz, Juan D

    2011-01-01

    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 ...

  12. Gas molecule adsorption in carbon nanotubes and nanotube bundles

    Microsoft Academic Search

    Jijun Zhao; Alper Buldum; Jie Han; Jian Ping Lu

    2002-01-01

    We studied various gas molecules (NO2, O2, NH3, N2, CO2, CH4, H2O, H2, Ar) on single-walled carbon nanotubes (SWNTs) and bundles using first principles methods. The equilibrium position, adsorption energy, charge transfer, and electronic band structures are obtained for different kinds of SWNTs. Most molecules adsorb weakly on SWNTs and can be either charge donors or acceptors to the nanotubes.

  13. Scaling of Excitons in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Perebeinos, Vasili; Tersoff, J.; Avouris, Phaedon

    2004-06-01

    Light emission from carbon nanotubes is expected to be dominated by excitonic recombination. Here we calculate the properties of excitons in nanotubes embedded in a dielectric, for a wide range of tube radii and dielectric environments. We find that simple scaling relationships give a good description of the binding energy, exciton size, and oscillator strength.

  14. Properties of composites of carbon nanotube fibres

    Microsoft Academic Search

    R. J. Mora; J. J. Vilatela; A. H. Windle

    2009-01-01

    Composites have set the standard for high strength materials for several decades. With the discovery of nanotubes, new possibilities for reinforced composites have arisen, with potential mechanical properties superior to those of currently available materials. This paper reports the properties of epoxy matrix reinforced with fibres of carbon nanotubes (CNTs) which, in many ways, are similar to standard composites reinforced

  15. One-step grown suspended n-type semiconducting single wall carbon nanotube field effect transistors with carbon nanotube electrodes

    NASA Astrophysics Data System (ADS)

    Lee, Yun-Hi; Lee, Jong-Hee; Noh, Ji-Young

    2008-01-01

    The authors report on the in situ formation of n-type ferromagnetic single wall carbon nanotube field effect transistors for the first time using a rapid heating process with a continuous flow of H2 gas under a vacuum of millitorr and their electromagnetic transport properties. The suspended n-type single wall carbon nanotube (SWNT) bridge including nanosized Fe catalyst impurities also shows gate controlled magnetic field dependent field effect behavior. The interesting features of these devices can be understood qualitatively based on the influence of the nonoxidant interface and nano Fe residing at the growth site of the SWNT bridge.

  16. Luttinger liquid behavior in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Egger, Reinhold

    The low-energy theory of metallic carbon nanotubes is derived by bosonization methods. For single-wall nanotubes, the electron-electron interaction destroys the Fermi liquid state and leads to Luttinger liquid behavior. For individual multi-wall nanotubes or a rope of single-wall nanotubes, correlations are also important and can imply Luttinger liquid behavior again. Characteristic Luttinger liquid power laws are found for the tunneling density of states and the linear conductance in the presence of a backscatterer, with exponents approaching their Fermi liquid value only very slowly as the number of conducting shells or tubes increases.

  17. Carbon nanotube heat-exchange systems

    DOEpatents

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

    2008-11-11

    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).

  18. Carbon nanotube bearings in theory and practice

    E-print Network

    Cook, Eugene Hightower

    2011-01-01

    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 ...

  19. Carbon nanotube-based field ionization vacuum

    E-print Network

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

    2012-01-01

    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 ...

  20. Stiffness matrices of carbon nanotube structures

    E-print Network

    Samaroo, Kirk J. (Kirk Jerome)

    2005-01-01

    An analytical modeling study was done to determine the stiffness matrices of the lattice structure of graphene, the planar building block of carbon nanotubes. Through continuum linear elastic analysis and a displacement-based ...

  1. Carbon nanotube polymer composition and devices

    DOEpatents

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

    2011-06-14

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

  2. Polystyrene grafted multi-walled carbon nanotubes.

    PubMed

    Shaffer, M S P; Koziol, K

    2002-09-21

    Oxidised, multi-walled, carbon nanotubes can be grafted with polystyrene molecules using an situ radical polymerisation reaction, thereby dramatically modifying their solubility and their suitability for nanocomposite applications. PMID:12357785

  3. Plasma-induced alignment of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Bower, Chris; Zhu, Wei; Jin, Sungho; Zhou, Otto

    2000-08-01

    Uniform films of well-aligned carbon nanotubes have been grown using microwave plasma-enhanced chemical vapor deposition. It is shown that nanotubes can be grown on contoured surfaces and aligned in a direction always perpendicular to the local substrate surface. The alignment is primarily induced by the electrical self-bias field imposed on the substrate surface from the plasma environment. It is found that switching the plasma source off effectively turns the alignment mechanism off, leading to a smooth transition between the plasma-grown straight nanotubes and the thermally grown "curly" nanotubes. The nanotubes grow at a surprisingly high rate of ˜100 nm/s in our plasma process, which may be important for large-scale commercial production of nanotubes.

  4. Photon harvesting with multi wall carbon nanotubes

    Microsoft Academic Search

    M. Scarselli; C. Scilletta; F. Tombolini; P. Castrucci; M. De Crescenzi; M. Diociaiuti; S. Casciardi; E. Gatto; M. Venanzi

    2009-01-01

    In this work we show that a sizeable enhancement in the photocurrent over the visible and near ultraviolet energy range can be obtained from multi-wall carbon nanotubes when decorated with Cu-nanoparticles. The result has been obtained both from electrochemical and solid state cells measurements. The photoactive metal nanoparticles do not change the intrinsic ability of multi-wall carbon nanotubes to behave

  5. Carbon nanotube integrated multifunctional multiscale composites

    Microsoft Academic Search

    Jingjing Qiu; Chuck Zhang; Ben Wang; Richard Liang

    2007-01-01

    Carbon nanotubes (CNTs) demonstrate extraordinary properties and show great promise in enhancing out-of-plane properties of traditional polymer composites and enabling functionality, but current manufacturing challenges hinder the realization of their potential. This paper presents a method to fabricate multifunctional multiscale composites through an effective infiltration-based vacuum-assisted resin transfer moulding (VARTM) process. Multi-walled carbon nanotubes (MWNTs) were infused through and between

  6. Metal-Enhanced Fluorescence of Carbon Nanotubes

    Microsoft Academic Search

    Guosong Hong; Scott M. Tabakman; Kevin Welsher; Hailiang Wang; Xinran Wang; Hongjie Dai

    2010-01-01

    The photoluminescence (PL) quantum yield of single-walled carbon nanotubes (SWNTs) is relatively low, with various quenching effects by metallic species reported in the literature. Here, we report the first case of metal enhanced fluorescence (MEF) of surfactant-coated carbon nanotubes on nanostructured gold substrates. The photoluminescence quantum yield of SWNTs is observed to be enhanced more than 10-fold. The dependence of

  7. Fundamental transmitting properties of carbon nanotube antennas

    Microsoft Academic Search

    G. W. Hanson

    2005-01-01

    P.J. Burke et al. (see http:\\/\\/xxx.lanl.gov\\/abs\\/cond-mat\\/0408418) considered carbon nanotube dipole antennas based on a transmission-line model. This paper investigates fundamental properties of dipole antennas formed by carbon nanotubes using a Halle´n's-type integral equation. The input impedance, radiation pattern, and current profiles are presented and compared to those of ordinary metallic antennas of the same size and shape. Possible applications of

  8. Filling of carbon nanotubes and nanofibres.

    PubMed

    Gately, Reece D; In Het Panhuis, Marc

    2015-01-01

    The reliable production of carbon nanotubes and nanofibres is a relatively new development, and due to their unique structure, there has been much interest in filling their hollow interiors. In this review, we provide an overview of the most common approaches for filling these carbon nanostructures. We highlight that filled carbon nanostructures are an emerging material for biomedical applications. PMID:25821693

  9. Carbon Nanotube Based Nanofluidic Devices

    NASA Astrophysics Data System (ADS)

    Pang, Pei

    Nanofluidic devices in which one single-walled carbon nanotube (SWCNT) spans a barrier between two fluid reservoirs were constructed, enabling direct electrical measurement of the transport of ions and molecules. Ion current through these devices is about 2 orders of magnitude larger than that predicted from the bulk resistivity of the electrolyte. Electroosmosis drives excess current, carried by cations, and is found to be the origin of giant ionic current through SWCNT as shown by building an ionic field-effect transistor with a gate electrode embedded in the fluid barrier. Wetting of inside of the semi-conducting SWCNT by water showed the change of its electronic property, turning the electronic SWCNT field-effect transistor to "on" state. These findings provide a new method to investigate and control the ion and molecule behavior at nanoscale.

  10. Carbon Nanotube Based Light Sensor

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    A light sensor substrate comprises a base made from a semi-conductive material and topped with a layer of an electrically non-conductive material. A first electrode and a plurality of carbon nanotube (CNT)-based conductors are positioned on the layer of electrically non-conductive material with the CNT-based conductors being distributed in a spaced apart fashion about a periphery of the first electrode. Each CNT-based conductor is coupled on one end thereof to the first electrode and extends away from the first electrode to terminate at a second free end. A second or gate electrode is positioned on the non-conductive material layer and is spaced apart from the second free end of each CNT-based conductor. Coupled to the first and second electrode is a device for detecting electron transfer along the CNT-based conductors resulting from light impinging on the CNT-based conductors.

  11. Photonics based on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Gu, Qingyuan; Gicquel-Guézo, Maud; Loualiche, Slimane; Pouliquen, Julie Le; Batte, Thomas; Folliot, Hervé; Dehaese, Olivier; Grillot, Frederic; Battie, Yann; Loiseau, Annick; Liang, Baolai; Huffaker, Diana

    2013-06-01

    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.

  12. Carbon Nanotubes and Bucky Materials

    NASA Astrophysics Data System (ADS)

    Baxendale, Mark

    The chapter details the underlying phenomena that underpin electronic applications that have followed from the discoveries of C60 and carbon nanotubes. The reduced dimensionality of these self-organised structures, high electron mobility, weak electromigration, and the plethora of quantum electronic effects exhibited by these structures suggest they are serious candidates for molecular electronics. The detail of the surface chemistry and conditions of synthesis assume greater importance than for conventional electronic materials since all atoms are on the exterior of these structures, as is outlined with references to the wider literature. Essential electronic structure information is given with reference to the transport measurements that have contributed greatly to the evolution of the field with emphasis on the Coulomb blockade and ballistic transport phenomena. The major electronic applications are then outlined, giving the state-of-the-art figures of merit for performance and comments on prospects for realisation.

  13. Functionalized carbon nanotubes: biomedical applications

    PubMed Central

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

    2012-01-01

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

  14. Carbon nanotubes for biomedical imaging: the recent advances.

    PubMed

    Gong, Hua; Peng, Rui; Liu, Zhuang

    2013-12-01

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

  15. Fundamental optical processes in armchair carbon nanotubes

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  16. Fundamental optical processes in armchair carbon nanotubes.

    PubMed

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

    2013-02-21

    Single-wall carbon nanotubes provide ideal model one-dimensional (1-D) condensed matter systems in which to address fundamental questions in many-body physics, while, at the same time, they are leading candidates for building blocks in nanoscale optoelectronic circuits. Much attention has been recently paid to their optical properties, arising from 1-D excitons and phonons, which have been revealed via photoluminescence, Raman scattering, and ultrafast optical spectroscopy of semiconducting carbon nanotubes. On the other hand, dynamical properties of metallic nanotubes have been poorly explored, although they are expected to provide a novel setting for the study of electron-hole pairs in the presence of degenerate 1-D electrons. In particular, (n,n)-chirality, or armchair, metallic nanotubes are truly gapless with massless carriers, ideally suited for dynamical studies of Tomonaga-Luttinger liquids. Unfortunately, progress towards such studies has been slowed by the inherent problem of nanotube synthesis whereby both semiconducting and metallic nanotubes are produced. Here, we use post-synthesis separation methods based on density gradient ultracentrifugation and DNA-based ion-exchange chromatography to produce aqueous suspensions strongly enriched in armchair nanotubes. Through resonant Raman spectroscopy of the radial breathing mode phonons, we provide macroscopic and unambiguous evidence that density gradient ultracentrifugation can enrich ensemble samples in armchair nanotubes. Furthermore, using conventional, optical absorption spectroscopy in the near-infrared and visible range, we show that interband absorption in armchair nanotubes is strongly excitonic. Lastly, by examining the G-band mode in Raman spectra, we determine that observation of the broad, lower frequency (G(-)) feature is a result of resonance with non-armchair "metallic" nanotubes. These findings regarding the fundamental optical absorption and scattering processes in metallic carbon nanotubes lay the foundation for further spectroscopic studies to probe many-body physical phenomena in one dimension. PMID:23340668

  17. Engineering molecular chains in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chamberlain, Thomas W.; Pfeiffer, Rudolf; Howells, Jonathan; Peterlik, Herwig; Kuzmany, Hans; Kräutler, Bernhard; da Ros, Tatiana; Melle-Franco, Manuel; Zerbetto, Francesco; Mili?, Dragana; Khlobystov, Andrei N.

    2012-11-01

    A range of mono- and bis-functionalised fullerenes have been synthesised and inserted into single-walled carbon nanotubes. The effect of the size and shape of the functional groups of the fullerenes on the resultant 1D arrays formed within the nanotubes was investigated by high resolution transmission electron microscopy and X-ray diffraction. The addition of non-planar, sterically bulky chains to the fullerene cage results in highly ordered 1D structures in which the fullerenes are evenly spaced along the internal nanotube cavity. Theoretical calculations reveal that the functional groups interact with neighbouring fullerene cages to space the fullerenes evenly within the confines of the nanotube. The addition of two functional groups to opposite sides of the fullerene cages results in a further increase in the separation of the fullerene cages within the nanotubes at the cost of lower nanotube filling rates.A range of mono- and bis-functionalised fullerenes have been synthesised and inserted into single-walled carbon nanotubes. The effect of the size and shape of the functional groups of the fullerenes on the resultant 1D arrays formed within the nanotubes was investigated by high resolution transmission electron microscopy and X-ray diffraction. The addition of non-planar, sterically bulky chains to the fullerene cage results in highly ordered 1D structures in which the fullerenes are evenly spaced along the internal nanotube cavity. Theoretical calculations reveal that the functional groups interact with neighbouring fullerene cages to space the fullerenes evenly within the confines of the nanotube. The addition of two functional groups to opposite sides of the fullerene cages results in a further increase in the separation of the fullerene cages within the nanotubes at the cost of lower nanotube filling rates. Electronic supplementary information (ESI) available: HRTEM images of 4@SWNT, space filling models of 1-6@SWNT structures and crystal packing considerations of 6. See DOI: 10.1039/c2nr32571c

  18. Doped Carbon Nanotubes: Synthesis, Characterization and Applications

    Microsoft Academic Search

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

    \\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-,

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

    E-print Network

    Zhigilei, Leonid V.

    Heat conduction in carbon nanotube materials: Strong effect of intrinsic thermal conductivity conductivity of interconnected networks of bundles in carbon nanotube (CNT) films reveals a strong effect to the thermal resistance of a CNT segment with Leq ¼ 59 lm. At first sight, this estimation appears to support

  20. Toward Large Arrays of Multiplex Functionalized Carbon Nanotube

    E-print Network

    Javey, Ali

    Toward Large Arrays of Multiplex Functionalized Carbon Nanotube Sensors for Highly Sensitive single-walled carbon nanotubes (SWNT) bridging metal electrodes are obtained by chemical vapor deposition (CVD) of nanotubes across prefabricated electrode arrays. The ensemble of nanotubes in such a device

  1. Hydrogen Raman shifts in carbon nanotubes from molecular dynamics simulation

    E-print Network

    Brenner, Donald W.

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

  2. 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)

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

    2013-11-01

    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.

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

    PubMed

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

    2014-01-30

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

  5. Titanium Doped Carbon Nanotubes for Hydrogen Storage

    NASA Astrophysics Data System (ADS)

    Fennick, Jake; Lewis, James

    2008-03-01

    An efficient method of storing hydrogen is necessary before fuel cells can become practical. Previous computational results show that a single titanium atom adsorbed on the surface of a carbon nanotube can bind up to 4 hydrogen molecules. We pursue simulations of hydrogen packed between two titanium-doped carbon nanotubes. The highest percentage weight of storage and the manner in which these parallel nanotubes pack is of particular interest. Calculations are performed with the classical MD program GULP. After computation, automated analysis will choose the combination of parameters that results in the most efficient hydrogen storage for these titanium-doped carbon nanotube systems. [1] Yildrim, T.; Ciraci, S. Phys. ReV. Lett. 2005, 94, 175501.

  6. Biocompatibility of iron filled carbon nanotubes in vitro.

    PubMed

    Taylor, Arthur; Lipert, Kamil; Krämer, Kai; Hampel, Silke; Füssel, Susanne; Meye, Axel; Klingeler, Rüdiger; Ritschel, Manfred; Leonhardt, Albrecht; Büchner, Bernd; Wirth, Manfred P

    2009-10-01

    Due to their particular magnetic properties, nanoparticles of metallic iron are promising candidates for magnetic fluid hyperthermia when compared to the commonly used iron oxides. However, the difficulty of handling these structures in ambient conditions without oxidation hinders its practical application. In this work, iron filled carbon nanotubes non-covalently functionalized by human serum albumin are studied as potential agents for hyperthermia. Here the iron is encapsulated inside of the carbon shells and protected from reactions with its environment. Besides protecting the iron and biological environment against each other, the carbon shells can also work as an interface for conjugation with other biological molecules of interest. In order to assess if such structures could induce any toxic effect in human cell cultures, we have probed its biocompatibility on a dosage and time dependent manner by measuring metabolic activity, cell proliferation, cell cycle distribution and apoptosis. Our results have shown that those nanotubes strongly associate with cells within a short incubation period and do not pose any significant toxic effect. The magnetic properties of iron filled carbon nanotubes in biological environment, i.e., associated to cells, have been studied and a possible rotation as a function of the applied magnetic field is discussed. Our initial findings encourage the further study of these structures as potential hyperthermia agents. PMID:19908442

  7. Underwater sound generation using carbon nanotube projectors.

    PubMed

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

    2010-07-14

    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

  8. Splitting and joining in carbon nanotube/nanoribbon/nanotetrahedron growth.

    PubMed

    Hasegawa, Takayuki; Kohno, Hideo

    2015-02-01

    We report a novel phenomenon for carbon nanotube growth that results in a new carbon nanotube morphology. A carbon nanotube grown via metal nanoparticle-catalyzed chemical vapor deposition splits into two flattened nanotubes during growth and the two flattened nanotubes merge to form a ring of carbon nanotube/nanoribbon. This novel process is revealed by transmission electron microscopy observations of the carbon nanostructures. We propose that the splitting-and-joining process involves only one metal catalyst nanoparticle and a self-folding mechanism that we have named the origami mechanism to explain the process and the formation of nanoribbons and nanotetrahedra. PMID:25559588

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

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

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

  10. Electrochemical storage of energy in carbon nanotubes and nanostructured carbons

    Microsoft Academic Search

    Elzbieta Frackowiak; François Béguin

    2002-01-01

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

  11. Thermal conductivity and thermal rectification in unzipped carbon nanotubes.

    PubMed

    Ni, Xiaoxi; Zhang, Gang; Li, Baowen

    2011-06-01

    We study the thermal transport in completely unzipped carbon nanotubes, which are called graphene nanoribbons, partially unzipped carbon nanotubes, which can be seen as carbon-nanotube-graphene-nanoribbon junctions, and carbon nanotubes by using molecular dynamics simulations. It is found that the thermal conductivity of a graphene nanoribbon is much less than that of its perfect carbon nanotube counterparts because of the localized phonon modes at the boundary. A partially unzipped carbon nanotube has the lowest thermal conductivity due to additional localized modes at the junction region. More strikingly, a significant thermal rectification effect is observed in both partially unzipped armchair and zigzag carbon nanotubes. Our results suggest that carbon-nanotube-graphene-nanoribbon junctions can be used in thermal energy control. PMID:21555836

  12. Release characteristics of selected carbon nanotube polymer composites

    EPA Science Inventory

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

  13. Enhancement of carbon nanotube photoluminescence by photonic crystal nanocavities

    E-print Network

    Maruyama, Shigeo

    Enhancement of carbon nanotube photoluminescence by photonic crystal nanocavities R. Watahiki,1 T 153-8505, Japan Photonic crystal nanocavities are used to enhance photoluminescence from single the emission wavelengths of carbon nanotubes, demonstrating the ability to enhance photoluminescence from

  14. Carbon Nanotube Reinforced Polymers for Radiation Shielding Applications

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  15. Uniform Diffusion of Acetonitrile inside Carbon Nanotubes Favors

    E-print Network

    Uniform Diffusion of Acetonitrile inside Carbon Nanotubes Favors Supercapacitor Performance Oleg N of liquid acetonitrile (AN) confined inside carbon nanotubes (CNTs) is predicted by molecular dynamics requires polar but aprotic solvents such as acetonitrile (AN). AN's structural, transport, and solvation

  16. A Generic Approach to Coat Carbon Nanotubes With Nanoparticles

    E-print Network

    Chen, Junhong

    A Generic Approach to Coat Carbon Nanotubes With Nanoparticles for Potential Energy Applications vari- ous nanoparticles onto multiwalled carbon nanotubes (CNTs). Charged and nonagglomerated aerosol coated with nanoparticles of multiple materials to realize the multicomponent coating. High resolution

  17. A multiscale projection method for the analysis of carbon nanotubes

    E-print Network

    Qian, Dong

    to exist: single-walled carbon nanotube (SWCNT) and multiwalled carbon nanotube (MWCNT). SWCNT of slightly twisted bundles [57]. In contrast, an MWCNT is made up of nested shells of cylinders with weak

  18. Oscillatory characteristics of carbon nanotubes inside carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Ansari, R.; Alipour, A.; Sadeghi, F.

    2012-12-01

    This article presents a comprehensive study on the mechanics of carbon nanotubes (CNTs) oscillating in CNT bundles. Using the continuum approximation along with Lennard-Jones (LJ) potential function, new semi-analytical expressions in terms of double integrals are presented to evaluate van der Waals (vdW) potential energy and interaction force upon which the equation of motion is directly solved. The obtained potential expression enables one to arrive at a new semi-analytical formula for the exact evaluation of oscillation frequency. Also, an algebraic frequency formula is extracted on the basis of the simplifying assumption of constant vdW force. Based on the present expressions, a thorough study on various aspects of operating frequencies under different system parameters is given, which permits fresh insight into the problem. The strong dependence of oscillation frequency on system parameters, such as the extrusion distance and initial velocity of the core as initial conditions for the motion is indicated. Interestingly, a specific initial velocity is found at which the oscillation frequency is independent of the core length. In addition, a relation between this specific initial velocity and the escape velocity is disclosed.

  19. Covalent decoration of multi-walled carbon nanotubes with silica nanoparticles

    Microsoft Academic Search

    Massimo Bottini; Lutz Tautz; Huong Huynh; Edvard Monosov; Nunzio Bottini; Marcia I. Dawson; Stefano Bellucci; Tomas Mustelin

    2005-01-01

    We describe a novel tunable approach for the synthesis of carbon nanotube-silica nanobead composites. The control of nanotube morphology and bead size coupled with the versatility of silica chemistry makes these structures an excellent platform for the development of biosensors, or for optical, magnetic and catalytic applications. Nanomaterials are being developed for medical and biotechnolo- gical applications including gene delivery,

  20. Carbon Nanotubes and Chronic Granulomatous Disease

    PubMed Central

    Barna, Barbara P.; Judson, Marc A.; Thomassen, Mary Jane

    2014-01-01

    Use of nanomaterials in manufactured consumer products is a rapidly expanding industry and potential toxicities are just beginning to be explored. Combustion-generated multiwall carbon nanotubes (MWCNT) or nanoparticles are ubiquitous in non-manufacturing environments and detectable in vapors from diesel fuel, methane, propane, and natural gas. In experimental animal models, carbon nanotubes have been shown to induce granulomas or other inflammatory changes. Evidence suggesting potential involvement of carbon nanomaterials in human granulomatous disease, has been gathered from analyses of dusts generated in the World Trade Center disaster combined with epidemiological data showing a subsequent increase in granulomatous disease of first responders. In this review we will discuss evidence for similarities in the pathophysiology of carbon nanotube-induced pulmonary disease in experimental animals with that of the human granulomatous disease, sarcoidosis. PMID:25525507

  1. Carbon Nanotube Tower-Based Supercapacitor

    NASA Technical Reports Server (NTRS)

    Meyyappan, Meyya (Inventor)

    2012-01-01

    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.

  2. Carbon nanotube-based synthetic gecko tapes

    PubMed Central

    Ge, Liehui; Sethi, Sunny; Ci, Lijie; Ajayan, Pulickel M.; Dhinojwala, Ali

    2007-01-01

    We have developed a synthetic gecko tape by transferring micropatterned carbon nanotube arrays onto flexible polymer tape based on the hierarchical structure found on the foot of a gecko lizard. The gecko tape can support a shear stress (36 N/cm2) nearly four times higher than the gecko foot and sticks to a variety of surfaces, including Teflon. Both the micrometer-size setae (replicated by nanotube bundles) and nanometer-size spatulas (individual nanotubes) are necessary to achieve macroscopic shear adhesion and to translate the weak van der Waals interactions into high shear forces. We have demonstrated for the first time a macroscopic flexible patch that can be used repeatedly with peeling and adhesive properties better than the natural gecko foot. The carbon nanotube-based tape offers an excellent synthetic option as a dry conductive reversible adhesive in microelectronics, robotics, and space applications. PMID:17578915

  3. Carbon nanotube-based synthetic gecko tapes.

    PubMed

    Ge, Liehui; Sethi, Sunny; Ci, Lijie; Ajayan, Pulickel M; Dhinojwala, Ali

    2007-06-26

    We have developed a synthetic gecko tape by transferring micropatterned carbon nanotube arrays onto flexible polymer tape based on the hierarchical structure found on the foot of a gecko lizard. The gecko tape can support a shear stress (36 N/cm(2)) nearly four times higher than the gecko foot and sticks to a variety of surfaces, including Teflon. Both the micrometer-size setae (replicated by nanotube bundles) and nanometer-size spatulas (individual nanotubes) are necessary to achieve macroscopic shear adhesion and to translate the weak van der Waals interactions into high shear forces. We have demonstrated for the first time a macroscopic flexible patch that can be used repeatedly with peeling and adhesive properties better than the natural gecko foot. The carbon nanotube-based tape offers an excellent synthetic option as a dry conductive reversible adhesive in microelectronics, robotics, and space applications. PMID:17578915

  4. Microscopic growth mechanisms for carbon nanotubes

    SciTech Connect

    Charlier, J.C.; De Vita, A.; Blase, X.; Car, R. [Institut Romand de Recherche Numerique en Physique des Materiaux, Lausanne (Switzerland)

    1997-01-31

    The uncatalyzed edge growth of carbon nanotubes was investigated by first-principles molecular dynamics simulations. At experimental temperatures the open end of single-walled nanotubes closed spontaneously into a graphitic dome, which may explain why these nanotubes do not grow in the absence of transition metal catalysts. On the other hand, chemical bonding between the edges of adjacent coaxial tubes ({open_quotes}lip-lip{close_quotes} interactions) trapped the end of a double-walled nanotube in a metastable energy minimum, thus preventing dome closure. These calculations show that this end geometry exhibits a high degree of chemical activity and easily accommodates incoming carbon fragments, supporting a model of growth by chemisorption from the vapor phase. 29 refs., 3 figs.

  5. Narrow graphene nanoribbons from carbon nanotubes

    Microsoft Academic Search

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

    2009-01-01

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

  6. Carbon nanotube electrode for oxidation of dopamine

    Microsoft Academic Search

    P. J. Britto; K. S. V. Santhanam; P. M. Ajayan

    1996-01-01

    Carbon nanotube electrodes were constructed using bromoform as binder, and the oxidative behaviour of dopamine was examined at these electrodes. The two-electron oxidation of dopamine to dopaminequinone showed ideal reversibility in cyclic voltammetry, and was significantly superior to that observed at other carbon electrodes. The electrode treated with goat's brain tissue homogenate showed the same features as the untreated electrode.

  7. Elastic and Plastic Deformation of Carbon Nanotubes

    Microsoft Academic Search

    M. Sato

    2011-01-01

    Carbon nanotubes (CNTs) consist of a graphene sheet (two-dimensional hexagonal lattices of carbon atoms) rolled up into a cylinder. This nanoscale structure has generated enormous interest in the research field of science and engineering in the last decades because of its excellent mechanical properties. For example, Young's modulus of CNTs is estimated to be on the order of TPa (i.e.,

  8. Application of Laplace Transform for the Exact Effect of a Magnetic Field on Heat Transfer of Carbon Nanotubes-Suspended Nanofluids

    NASA Astrophysics Data System (ADS)

    Ebaid, Abdelhalim; Al Sharif, Mohammed A.

    2015-06-01

    Since the discovery of the carbon nanotubes (CNTs), there is an increasing interest in their applications in industry and medical fields. Attempts of using such CNTs as drug carriers and in cancer therapy in the presence of a magnetic field are now undertaken because of their direct impacts on increasing the thermal conductivity of base fluids. Two types of CNTs are well known for the researchers, the single-walled CNT (SWCNTs) and the multi-walled CNTs (MWCNTs); however, the subject of which one is more effective in treatment of cancer deserves more investigations. The present article discusses the effect of such types of CNTs on the flow and heat transfer of nanofluids in the presence of a magnetic field. Exact analytical solution for the heat equation has been obtained by using the Laplace transform, where the solution is expressed in terms of a new special function, the generalised incomplete gamma function. The effects of various parameters on the fluid velocity, temperature distribution, and heat transfer rates have been introduced. Details of possible applications of the current results in the treatment of cancer have been also discussed.

  9. Kondo Effects in Carbon Nanotubes Master of Science Thesis

    E-print Network

    Nygård, Jesper

    Kondo Effects in Carbon Nanotubes Master of Science Thesis Faculty of Science University of Copenhagen January 2007 Jeppe Vilstrup Holm The Niels Bohr Institute #12;Kondo Effects in Carbon Nanotubes- teresting physical phenomenon, including Coulomb blockade and Kondo physics in carbon nanotubes. It has been

  10. Carbon nanotubes as nanomedicines: From toxicology to pharmacology

    Microsoft Academic Search

    Lara Lacerda; Alberto Bianco; Maurizio Prato; Kostas Kostarelos

    2006-01-01

    Various biomedical applications of carbon nanotubes have been proposed in the last few years leading to the emergence of a new field in diagnostics and therapeutics. Most of these applications will involve the administration or implantation of carbon nanotubes and their matrices into patients. The toxicological and pharmacological profile of such carbon nanotube systems developed as nanomedicines will have to

  11. Critique of High-Frequency Performance of Carbon Nanotube FETs

    E-print Network

    Pulfrey, David L.

    Critique of High-Frequency Performance of Carbon Nanotube FETs David L. Pulfrey Department performance of carbon nanotube field-effect tran- sistors (CNFETs) is critically reviewed. The focus that render carbon nanotubes of interest for electronic devices. Field-effect transistors have been made from

  12. Respiratory toxicity of multi-wall carbon nanotubes

    Microsoft Academic Search

    Julie Muller; François Huaux; Nicolas Moreau; Pierre Misson; Jean-François Heilier; Monique Delos; Mohammed Arras; Antonio Fonseca; Janos B. Nagy; Dominique Lison

    2005-01-01

    Carbon nanotubes focus the attention of many scientists because of their huge potential of industrial applications, but there is a paucity of information on the toxicological properties of this material. The aim of this experimental study was to characterize the biological reactivity of purified multi-wall carbon nanotubes in the rat lung and in vitro. Multi-wall carbon nanotubes (CNT) or ground

  13. Identifying the Mechanism of Biosensing with Carbon Nanotube

    E-print Network

    Dekker, Cees

    for biosensing with nanotubes. Nanoscale semiconducting materials such as carbon nano- tubes1-21 or nanowires22Identifying the Mechanism of Biosensing with Carbon Nanotube Transistors Iddo Heller, Anne M; Revised Manuscript Received December 1, 2007 ABSTRACT Carbon nanotube transistors have outstanding

  14. Defects in carbon nanotubes: Implications for mechanical properties

    Microsoft Academic Search

    Elif Ertekin

    2006-01-01

    The mechanical properties of graphene-based systems such as carbon nanotubes are remarkable. Carbon nanotubes are stiff in tension and torsion, and there are indications of plastic deformation: observations of strain stiffening in nanotube torsional shafts as well as direct observations of kink motion to assist with elongation. These observations suggest the importance of defects to the mechanical properties of carbon

  15. Symmetry of electron diffraction from single-walled carbon nanotubes

    E-print Network

    Qin, Lu-Chang

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

  16. Luttinger Liquid Behavior in Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Egger, Reinhold

    1999-12-01

    The low-energy theory for multiwall carbon nanotubes including the long-ranged Coulomb interactions, internal screening effects, and single-electron hopping between graphite shells is derived and analyzed by bosonization methods. Characteristic Luttinger liquid power laws are found for the tunneling density of states, with exponents approaching their Fermi liquid value only very slowly as the number of conducting shells increases. With minor modifications, the same conclusions apply to transport in ropes of single-wall nanotubes.

  17. Behavorial model of carbon nanotube programmable resistors

    Microsoft Academic Search

    WeiSheng Zhao; Christian Gamrat; Guillaume Agnus; Vincent Derycke; A. Filoramo; J.-P. Bourgoin

    2009-01-01

    Hybrid Nano (e.g. Nanotube, Nanowire) \\/CMOS circuits combine both the advantages of Nano-devices and CMOS technologies; they have thus become one of the most promising candidates to relax the intrinsic drawbacks of CMOS circuits beyond Moore's law. A behavioral simulation model for an hybrid Nano\\/CMOS design is presented in this paper. It is based on Optically Gated Carbon NanoTube Field

  18. Conductive silver thick films filled with carbon nanotubes

    Microsoft Academic Search

    Marcin Sloma; Malgorzata Jakubowska; Anna Mlozniak; Ryszard Jezior

    Search of new, better materials for conductive paste for thick film compositions deposited by screen printing was the main\\u000a aim of this work as well as influence investigations of carbon nanotubes addition to functional phase of thick film paste.\\u000a Different types of carbon nanotubes such as single-walled nanotubes (SWCNT), multi-walled nanotubes (MWCNT) and non purified\\u000a non segregated nanotube clusters were

  19. Large spin-orbit coupling in carbon nanotubes.

    PubMed

    Steele, G A; Pei, F; Laird, E A; Jol, J M; Meerwaldt, H B; Kouwenhoven, L P

    2013-01-01

    It has recently been recognised that the strong spin-orbit interaction present in solids can lead to new phenomena, such as materials with non-trivial topological order. Although the atomic spin-orbit coupling in carbon is weak, the spin-orbit coupling in carbon nanotubes can be significant due to their curved surface. Previous works have reported spin-orbit couplings in reasonable agreement with theory, and this coupling strength has formed the basis of a large number of theoretical proposals. Here we report a spin-orbit coupling in three carbon nanotube devices that is an order of magnitude larger than previously measured. We find a zero-field spin splitting of up to 3.4?meV, corresponding to a built-in effective magnetic field of 29?T aligned along the nanotube axis. Although the origin of the large spin-orbit coupling is not explained by existing theories, its strength is promising for applications of the spin-orbit interaction in carbon nanotubes devices. PMID:23481381

  20. Large spin-orbit coupling in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Steele, G. A.; Pei, F.; Laird, E. A.; Jol, J. M.; Meerwaldt, H. B.; Kouwenhoven, L. P.

    2013-03-01

    It has recently been recognised that the strong spin-orbit interaction present in solids can lead to new phenomena, such as materials with non-trivial topological order. Although the atomic spin-orbit coupling in carbon is weak, the spin-orbit coupling in carbon nanotubes can be significant due to their curved surface. Previous works have reported spin-orbit couplings in reasonable agreement with theory, and this coupling strength has formed the basis of a large number of theoretical proposals. Here we report a spin-orbit coupling in three carbon nanotube devices that is an order of magnitude larger than previously measured. We find a zero-field spin splitting of up to 3.4?meV, corresponding to a built-in effective magnetic field of 29?T aligned along the nanotube axis. Although the origin of the large spin-orbit coupling is not explained by existing theories, its strength is promising for applications of the spin-orbit interaction in carbon nanotubes devices.

  1. Does water dope carbon nanotubes?

    SciTech Connect

    Bell, Robert A.; Payne, Michael C. [Theory of Condensed Matter Group, Cavendish Laboratory, Cambridge (United Kingdom); Mostofi, Arash A. [Department of Materials and Department of Physics, and the Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, London SW7 2AZ (United Kingdom)

    2014-10-28

    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{sup ?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.

  2. Comment on ``Microwave attenuation of hydrogen plasma in carbon nanotubes''

    Microsoft Academic Search

    Afshin Moradi; Afshin

    2010-01-01

    In a recent article, Babaei and Solari [J. Appl. Phys. 104, 124315 (2008)] studied the effects of the electron temperature, and the external static magnetic field on the attenuation (ATT) of the microwave in the hydrogen plasma embedded inside the carbon nanotubes (CNTs), which were grown by iron-catalyzed high-pressure disproportionation (HiPco). They showed that the position of ATT peak shifts

  3. Carbon Nanotube-Enhanced Carbon-Phenenolic Ablator Material

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    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.

  4. Orientational Growth of Carbon Nanotube for Applications

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  5. Piezoresistive effect in carbon nanotube fibers.

    PubMed

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

    2014-11-25

    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

  6. Mechanical immobilization of Hela cells on aligned carbon nanotube array

    Microsoft Academic Search

    Hiroki Ago; Ei-ichiro Uchimura; Takeshi Saito; Satoshi Ohshima; Naoki Ishigami; Masaharu Tsuji; Motoo Yumura; Masato Miyake

    2006-01-01

    We demonstrate that an aligned multi-walled carbon nanotube array can immobilize Hela cells through insertion of the nanotube tips into the cell. The cells were immobilized by pressing onto the nanotube array with the aid of mild centrifugal force. The nanotube array fixed a much larger number of cells compared with the flat surface of a Si substrate, indicating strong

  7. Modeling of carbon nanotube clamping in tensile tests

    Microsoft Academic Search

    Chunyu Li; Rodney S. Ruoff; Tsu-Wei Chou

    2005-01-01

    In this paper, the stress distributions in carbon nanotube clamps such as those formed by the electron beam induced deposition (EBID) technique are analyzed and the contributing factors, including nanotube position, stiffness of clamp material, and thickness of the clamping pad between the AFM tip and the nanotube are examined for the case of tensile loading of the nanotube. The

  8. Anomalous aharonov-bohm gap oscillations in carbon nanotubes.

    PubMed

    Sangalli, Davide; Marini, Andrea

    2011-10-12

    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

  9. Carbon nanotube-clamped metal atomic chain

    PubMed Central

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

    2010-01-01

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

  10. Spontaneous Exciton Dissociation in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  11. Spontaneous exciton dissociation in carbon nanotubes.

    PubMed

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

    2014-03-21

    Simultaneous photoluminescence and photocurrent measurements on individual single-walled carbon nanotubes reveal spontaneous dissociation of excitons into free electron-hole pairs. The correlation of luminescence intensity and photocurrent shows that a significant fraction of excitons are dissociating before recombination. Furthermore, the combination of optical and electrical signals also allows for extraction of the absorption cross section and the oscillator strength. Our observations explain the reasons why photoconductivity measurements in single-walled carbon nanotubes are straightforward despite the large exciton binding energies. PMID:24702413

  12. Structure of Carbon Nanotube-dendrimer composite

    E-print Network

    V. Vasumathi; Debabrata Pramanik; A. K. Sood; Prabal K Maiti

    2012-12-13

    Using all atomistic molecular dynamics (MD) simulations we report the microscopic picture of the nanotube-dendrimer complex for PAMAM dendrimer of generation 2 to 4 and carbon nanotube of chirality (6,5). We find compact wrapping conformations of dendrimer onto the nanotube surface for all the three generations of PAMAM dendrimer. The degree of wrapping is more for non-protonated dendrimer compared to the protonated dendrimer. For comparison we also study the interaction of another dendrimer, poly(propyl ether imine) (PETIM), with nanotube and show that PAMAM dendrimer interacts strongly as compared to PETIM dendrimer as is evident from the distance of closest approach as well as the number of close contacts between the nanotube and dendrimer. We also calculate the binding energy between the nanotube and the dendrimer using MM/PBSA methods and attribute the strong binding to the charge transfer between them. Dendrimer wrapping on CNT will make it soluble and can act as an efficient dispersing agent for nanotube.

  13. Composition, Electronic and Magnetic Investigation of the Encapsulated ZnFe2O 4 Nanoparticles in Multiwall Carbon Nanotubes Containing Ni Residuals.

    PubMed

    Al Khabouri, Saja; Al Harthi, Salim; Maekawa, Toru; Nagaoka, Yutaka; Elzain, Mohamed E; Al Hinai, Ashraf; Al-Rawas, A D; Gismelseed, A M; Yousif, Ali A

    2015-12-01

    We report investigation on properties of multiwall carbon nanotubes (mCNTs) containing Ni residuals before and after encapsulation of zinc ferrite nanoparticles. The pristine tubes exhibit metallic character with a 0.3 eV reduction in the work function along with ferromagnetic behavior which is attributed to the Ni residuals incorporated during the preparation of tubes. Upon encapsulation of zinc ferrite nanoparticles, 0.5 eV shift in Fermi level position and a reduction in both the ? band density of state along with a change in the hybridized sp(2)/sp(3) ratio of the tubes from 2.04 to 1.39 are observed. As a result of the encapsulation, enhancement in the ? bands density of state and coating of the zinc ferrite nanoparticles by the internal layers of the CNTs in the direction along the tube axis is observed. Furthermore, Ni impurities inside the tubes are attracted to the encapsulated zinc ferrite nanoparticles, suggesting the possibility of using these particles as purifying agents for CNTs upon being synthesized using magnetic catalyst particles. Charge transfer from Ni/mCNTs to the ZnFe2O4 nanoparticles is evident via reduction of the density of states near the Fermi level and a 0.3 eV shift in the binding energy of C 1 s core level ionization. Furthermore, it is demonstrated that encapsulated zinc ferrite nanoparticles in mCNTs resulted in two interacting sub-systems featured by distinct blocking temperatures and enhanced magnetic properties; i.e., large coercivity of 501 Oe and saturation magnetization of 2.5 emu/g at 4 K. PMID:26068078

  14. Decoration of carbon nanotubes with iron oxide

    SciTech Connect

    Cao Huiqun [State Key Laboratory for Modification of Chemical Fibers and Polymer Material, College of Material Science and Engineer, Donghua University, Shanghai, 200051 (China); Zhu Meifang [State Key Laboratory for Modification of Chemical Fibers and Polymer Material, College of Material Science and Engineer, Donghua University, Shanghai, 200051 (China)]. E-mail: zmf@dhu.edu.cn; Li Yaogang [State Key Laboratory for Modification of Chemical Fibers and Polymer Material, College of Material Science and Engineer, Donghua University, Shanghai, 200051 (China)

    2006-04-15

    A magnetic composite of multiwalls carbon nanotubes (MWNTs) decorated with iron oxide nanoparticles was synthesized successfully by a simple and effective chemistry precipitation method. The composite was characterized by X-ray diffraction analysis (XRD), Moessbauer spectrum (MS), transmission electron microscopy (TEM), and Fourier transform spectroscopy (FTIR) techniques. The patterns of XRD and MS indicated that MWNTs, {gamma}-Fe{sub 2}O{sub 3}, and Fe{sub 3}O{sub 4} coexisted in the composite. The TEM observation indicated that the nanoparticles of iron oxide were attached on the surface of the MWNTs, and the sizes of the particles ranged from 25 to 80 nm. FTIR spectra showed that SO{sub 4} {sup -} functional groups existed on the surface of MWNTs after modification by sodium dodecylbenzene sulfonic acid (SDBS), which could immobilize Fe{sup 3+} ions onto the MWNTs. The hysteresis loops of the MWNTs and decorated MWNTs were measured by vibrating sample magnetometer (VSM), and the results showed that the composite was ferromagnetism with the saturated magnetization of 20.07 emu/g, and the coercive of 163.44 Oe.

  15. Mechanically interlocked single-wall carbon nanotubes.

    PubMed

    de Juan, Alberto; Pouillon, Yann; Ruiz-González, Luisa; Torres-Pardo, Almudena; Casado, Santiago; Martín, Nazario; Rubio, Ángel; Pérez, Emilio M

    2014-05-19

    Extensive research has been devoted to the chemical manipulation of carbon nanotubes. The attachment of molecular fragments through covalent-bond formation produces kinetically stable products, but implies the saturation of some of the C-C double bonds of the nanotubes. Supramolecular modification maintains the structure of the SWNTs but yields labile species. Herein, we present a strategy for the synthesis of mechanically interlocked derivatives of SWNTs (MINTs). In the key rotaxane-forming step, we employed macrocycle precursors equipped with two ?-extended tetrathiafulvalene SWNT recognition units and terminated with bisalkenes that were closed around the nanotubes through ring-closing metathesis (RCM). The mechanically interlocked nature of the derivatives was probed by analytical, spectroscopic, and microscopic techniques, as well as by appropriate control experiments. Individual macrocycles were observed by HR?STEM to circumscribe the nanotubes. PMID:24729452

  16. Transport Through Carbon Nanotube Wires

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  17. Micromechanics of carbon nanotube turfs

    NASA Astrophysics Data System (ADS)

    Torabi, Hamid

    Complex structures consisting of intertwined, nominally vertical carbon nanotubes (CNTs) are called turfs. Unique electrical, thermal, optical, and permeability properties of these turfs have attracted growing attention during the past decade, and have rendered them as appropriate candidates for applications such as contact thermal switches. These properties are controlled by the details of the turf microstructures. Due to the application of the turfs in different fields, they are subjected to different loading conditions. Deformation changes the microstructure of a CNT turf, which results in change of effective properties. Many researchers have recently studied the collective mechanical behavior of CNT turfs to compression loading, as this behavior determines their performance. However, their complex and intertwined structure must be investigated in more details to find the relation between their deformation and their underlying morphology. Under uniform compression experiments, CNT turfs exhibit irreversible collective buckling of a layer preceded by reorientation of CNT segments. Experimentally observed independence of the buckling stress and the buckling wavelength on the turf width suggests the existence of an intrinsic material length. To investigate the relationship the macroscopic material properties and the statistical parameters describing the nano-scale geometry of the turf (tortuosity, density and connectivity) we develop a nano-scale computational model, based on the representation of CNT segments as elastica finite elements with van der Waals interactions. The virtual turfs are generated by means of a constrained random walk algorithm and subsequent relaxation. The resulting computational model is robust and is capable of modeling the collective behavior of CNTs. We first establish the dependence of statistical parameters on the computational parameters used for turf generation, then establish relationships between post-buckling stress, initial elastic modulus and buckling wavelength on statistical turf parameters. Finally, we analyze the reorientation of buckling planes of individual CNTs during the collective buckling process.

  18. Impact of carbon nanotube length on electron transport in aligned carbon nanotube networks

    E-print Network

    Lee, Jeonyoon

    Here, we quantify the electron transport properties of aligned carbon nanotube (CNT) networks as a function of the CNT length, where the electrical conductivities may be tuned by up to 10× with anisotropies exceeding 40%. ...

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

    PubMed

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

    2011-10-15

    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

  20. Carbon nanotubes as optical biomedical sensors.

    PubMed

    Kruss, Sebastian; Hilmer, Andrew J; Zhang, Jingqing; Reuel, Nigel F; Mu, Bin; Strano, Michael S

    2013-12-01

    Biosensors are important tools in biomedical research. Moreover, they are becoming an essential part of modern healthcare. In the future, biosensor development will become even more crucial due to the demand for personalized-medicine, point-of care devices and cheaper diagnostic tools. Substantial advances in sensor technology are often fueled by the advent of new materials. Therefore, nanomaterials have motivated a large body of research and such materials have been implemented into biosensor devices. Among these new materials carbon nanotubes (CNTs) are especially promising building blocks for biosensors due to their unique electronic and optical properties. Carbon nanotubes are rolled-up cylinders of carbon monolayers (graphene). They can be chemically modified in such a way that biologically relevant molecules can be detected with high sensitivity and selectivity. In this review article we will discuss how carbon nanotubes can be used to create biosensors. We review the latest advancements of optical carbon nanotube based biosensors with a special focus on near-infrared (NIR)-fluorescence, Raman-scattering and fluorescence quenching. PMID:23906934

  1. Thermal properties of aligned carbon nanotube\\/carbon nanocomposites

    Microsoft Academic Search

    Qian-ming Gong; Zhi Li; Xiao-dong Bai; Dan Li; Yun Zhao; Ji Liang

    2004-01-01

    Aligned carbon nanotube\\/carbon (Acnt\\/C) nanocomposites were fabricated with traditional chemical vapor infiltration (CVI) technology. Thermal conductivities of as-deposited and graphitized samples were tested by laser flash method. Results show that although only half the density and half the fraction of reinforcing element compared with carbon\\/carbon (C\\/C) composites in this work, the thermal diffusivity of Acnt\\/C is generally 3–5 times that

  2. Quantum electron transport in toroidal carbon nanotubes with metallic leads.

    NASA Astrophysics Data System (ADS)

    Jack, Mark; Encinosa, Mario

    2007-03-01

    Carbon nanotubes and carbon nanotori possess all the interesting new electronic features seen in graphene e.g. massless Dirac fermion characteristics, small spin-orbit coupling effects, and quantized conductance, along with interesting curvature and boundary condition effects closing the tube to form a torus. The authors calculate electronic transport properties such as density-of-states and transmissivity for toroidal carbon nanotubes with attached metallic or carbon nanotube leads as functions of the lead positions. A tight-binding Hamiltonian for the nanotorus is applied to a 24-carbon-atom armchair unit cell. The closure of the straight tube to a toroidal geometry introduces an additional off-diagonal coupling term, not encountered for the straight case. The device Green's function is then evaluated in tight-binding approximation using a recursion method to systematically determine its diagonal and off-diagonal matrix elements. References: 1. M. Encinosa and M. Jack, Phys. Scr. 73 (2006) 439-442. 2. M. Encinosa and M. Jack, Excitation of surface dipole and solenoidal modes on toroidal structures. Photonics and Nanostructures (Elsevier), May 2006. (Submitted) 3. M. Encinosa and M. Jack, Dipole and solenoidal magnetic moments of electronic surface currents on toroidal nanostructures. J. of Computer-Aided Materials Design (Springer), May 2006. (In Press)

  3. A review of the mechanical properties of isolated carbon nanotubes and carbon nanotube composites

    Microsoft Academic Search

    M. M. Shokrieh; R. Rafiee

    2010-01-01

    A literature review on the prediction of Young’s modulus for carbon nanotubes, from both theoretical and experimental aspects,\\u000a is presented. The discrepancies between the values of Young’s modulus reported in the literature are analyzed, and different\\u000a trends of the results are discussed. The available analytical and numerical simulations for predicting the mechanical properties\\u000a of carbon nanotube composites are also reviewed.

  4. walled carbon nanotube, MWNT) 1(c) walled carbon nanotube, SWNT) 1 (a,b)

    E-print Network

    Maruyama, Shigeo

    50 100 SWNT 60 % (3) 450 4 SWNT 100 H2O2, 15% 5 (38) SEM 90 % 600nm600nm 600nm600nm Fig. 4 SEM images of SWNTs generated by laser-oven technique. (a) As generated, (b) Purified with H2O2-walled carbon nanotube (SWNT). (b) A bundle of SWNTs. (c) Multi-walled carbon nanotube (MWNT). *1 Synthesis

  5. EXCITON BEHAVIOR IN CARBON NANOTUBES: DIELECTRIC SCREENING AND DECAY DYNAMICS

    E-print Network

    ' & $ % EXCITON BEHAVIOR IN CARBON NANOTUBES: DIELECTRIC SCREENING AND DECAY DYNAMICS ANDREW GERALD BEHAVIOR IN CARBON NANOTUBES: DIELECTRIC SCREENING AND DECAY DYNAMICS by ANDREW GERALD WALSH B. S., Cornell place to work. To Mark, Craig, and Michele, thank you for all your support on the nanotube project. I

  6. 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...

  7. Quantized Electrical Conductance of Carbon nanotubes(CNTs) Boxiao Chen

    E-print Network

    La Rosa, Andres H.

    ]. The circumference of the nano-tubes is represented by the magnitudes of the chiral vector, = n1 +m2Quantized Electrical Conductance of Carbon nanotubes(CNTs) By Boxiao Chen PH 464: Applied Optics is due to the scattering of electrons inside the cells. Carbon nanotubes (CNTs) have proposed to use

  8. Synthesis of Carbon Nanotubes by Rolling up Patterned Graphene

    E-print Network

    Liu, Feng

    Synthesis of Carbon Nanotubes by Rolling up Patterned Graphene Nanoribbons Using Selective Atomic nanotubes (CNTs) that have exhibited a wealth of fascinating electrical, optical, and mechanical properties demonstrate a new method (U.S. Patent Appl., serial no. 60/908039) for synthesizing carbon nanotubes (CNTs

  9. Facile synthesis of multifunctional multiwalled carbon nanotubes/Fe{sub 3}O{sub 4} nanoparticles/polyaniline composite nanotubes

    SciTech Connect

    Kong, Lirong [Alan G. MacDiarmid Institute, Jilin University, Changchun 130012 (China); Lu Xiaofeng [Department of Biomedical Engineering, Washington University, St Louis, MI 63130 (United States); Zhang Wanjin [Alan G. MacDiarmid Institute, Jilin University, Changchun 130012 (China)], E-mail: wjzhang@jlu.edu.cn

    2008-03-15

    With an average diameter of 100-150 nm, composite nanotubes of polyaniline (PANI)/multiwalled carbon nanotubes (MWNTs) containing Fe{sub 3}O{sub 4} nanoparticles (NPs) were synthesized by a two-step method. First, we synthesized monodispersed Fe{sub 3}O{sub 4} NPs (d=17.6 nm, {sigma}=1.92 nm) on the surface of MWNTs and then decorated the nanocomposites with a PANI layer via a self-assembly method. SEM and TEM images indicated that the obtained samples had the morphologies of nanotubes. The molecular structure and composition of MWNTs/Fe{sub 3}O{sub 4} NPs/PANI nanotubes were characterized by Fourier transform infrared spectra (FTIR), energy dispersive X-ray spectrometry (EDX), X-ray photoelectron spectra (XPS), X-ray diffraction (XRD) and Raman spectra. UV-vis spectra confirmed the existence of PANI and its response to acid and alkali. As a multifunctional material, the conductivity and magnetic properties of MWNTs/Fe{sub 3}O{sub 4} NPs/PANI composites nanotubes were also investigated. - Graphical abstract: The work on preparing nanocomposites has been too much, but few reports were about synthesizing one-dimensional nanocomposite of three different nanoscale materials. In our work, we prepared one-dimensional multiwalled carbon nanotubes/Fe{sub 3}O{sub 4} particles/polyaniline composite nanotubes and studied their conductive and magnetic properties.

  10. Fluorecently labeled bionanotransporters of nucleic acid based on carbon nanotubes

    E-print Network

    Novopashina, D S; Venyaminova, A G

    2012-01-01

    Here we propose the approach to design of the new type of hybrids of oligonucleotides with fluorescein-functionalized single-walled carbon nanotubes. The approach is based on stacking interactions of functionalized nanotubes with pyrene residues in conjugates of oligonucleotides. The amino- and fluorescein-modified single-walled carbon nanotubes were obtained, and their physico-chemical properties were investigated. The effect of carbon nanotubes functionalization type on the efficacy of sorption of pyrene conjugates of oligonucleotides was examined. Proposed non-covalent hybrids of fluorescein-labeled carbon nanotubes with oligonucleotides may be used for intracellular transport of functional nucleic acids.

  11. Alignment dependent mechanical responses of carbon nanotubes to light

    SciTech Connect

    Lu Shaoxin; Ahir, Samit V.; Terentjev, Eugene M.; Panchapakesan, Balaji [Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States); Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States)

    2007-09-03

    The authors report the orientation dependent elastic responses of carbon nanotubes to infrared photons. Unaligned and partially aligned samples of single wall carbon nanotubes (SWCNTs) and multiwall carbon nanotubes (MWCNTs) were studied for orientation dependent mechanical responses. While partial alignment in MWCNT ensembles changed the mechanical response to photons from expansion to contraction, the speeds of photomechanical responses were increased at least an order of magnitude by nanotube partial alignment in both SWCNT and MCWNT samples. The unique alignment dependent reversible photomechanical responses of carbon nanotubes are critical for actuator applications.

  12. Flexible high-performance carbon nanotube integrated circuits

    Microsoft Academic Search

    Dong-Ming Sun; Marina Y. Timmermans; Ying Tian; Albert G. Nasibulin; Esko I. Kauppinen; Shigeru Kishimoto; Takashi Mizutani; Yutaka Ohno

    2011-01-01

    Carbon nanotube thin-film transistors are expected to enable the fabrication of high-performance, flexible and transparent devices using relatively simple techniques. However, as-grown nanotube networks usually contain both metallic and semiconducting nanotubes, which leads to a trade-off between charge-carrier mobility (which increases with greater metallic tube content) and on\\/off ratio (which decreases). Many approaches to separating metallic nanotubes from semiconducting nanotubes

  13. Damping of electron Zitterbewegung in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Rusin, Tomasz M.; Zawadzki, Wlodek

    2015-06-01

    Zitterbewegung (ZB, trembling motion) of electrons in semiconductor carbon nanotubes is described taking into account dephasing processes. The density matrix formalism is used for the theory. Differences between decay of ZB oscillations due to electron localization and that due to dephasing are discussed.

  14. Load transfer mechanism in carbon nanotube ropes

    Microsoft Academic Search

    Dong Qian; Rodney S. Ruoff

    2003-01-01

    We used molecular mechanics and molecular dynamics to study the nature of load transfer in a single walled carbon nanotube (SWCNT) bundle consisting of seven (10,10) SWCNTs: one core tube surrounded by six tubes on the perimeter. The surface tension and the inter-tube corrugation are identified as the two factors that contribute to load transfer. The surface tension effectively acts

  15. Carbon nanotubes as supports for inulinase immobilization.

    PubMed

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

    2014-01-01

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

  16. Hydrogen adsorption and storage in carbon nanotubes

    Microsoft Academic Search

    Seung Mi Lee; Ki Soo Park; Young Chul Choi; Young Soo Park; Jin Moon Bok; Dong Jae Bae; Kee Suk Nahm; Yong Gak Choi; Soo Chang Yu; Nam-gyun Kim; Thomas Frauenheim; Young Hee Lee

    2000-01-01

    A comprehensive studies on hydrogen adsorption and storage in carbon nanotubes (CNTs) have been done both experimentally and theoretically. Hydrogen atoms have been stored electrochemically in CNTs. We find that hydrogens exist as a form of H2 molecule in an empty space inside CNTs, which was confirmed by Raman spectra. Several adsorption sites in\\/on CNTs are observed during the discharging

  17. Carbon nanotube-reinforced aluminium strips

    Microsoft Academic Search

    Amal M. K. Esawi; Mostafa A. El Borady

    2008-01-01

    Carbon nanotubes (CNTs) have recently emerged as materials with outstanding properties. Researchers have investigated their use as reinforcements in – mainly – polymer, and ceramic matrices. Due to the anticipated fabrication difficulties, a few research groups have explored their use to reinforce metal matrices. Recently, conventional powder metallurgy techniques (compaction and sintering) were used with some success. In this paper,

  18. Conductance of AFM Deformed Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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.

  19. Carbon nanotubes: A bright future for defects

    NASA Astrophysics Data System (ADS)

    Wang, Qing Hua; Strano, Michael S.

    2013-10-01

    Covalently bonding groups to the walls of carbon nanotubes has been previously observed to quench their photoluminescence. Now, it has been shown that, if you get the chemistry just right, their photoluminescence can in fact be significantly brightened by introducing defects through functionalization.

  20. CVD growth of carbon nanotube bundle arrays

    Microsoft Academic Search

    Michael J. Bronikowski

    2006-01-01

    Recent discovery of enhanced field emission current intensity from arrays of bundles of carbon nanotubes (CNT) has prompted this investigation of the growth of CNT bundle arrays by metal-catalyzed chemical vapor deposition (CVD), in order to understand and control the growth of these arrays. CNT bundle array growth has been characterized as a function of array geometric parameters: the CNT

  1. Carbon nanotube based functional superhydrophobic coatings

    Microsoft Academic Search

    Sunny Sethi

    2010-01-01

    The main objective of this dissertation is synthesis of carbon nanotube (CNT) based superhydrophobic materials. The materials were designed such that electrical and mechanical properties of CNTs could be combined with superhydrophobicity to create materials with unique properties, such as self-cleaning adhesives, miniature flotation devices, ice-repellant coatings, and coatings for heat transfer furnaces. The coatings were divided into two broad

  2. Growth of decorated carbon nano-tubes

    Microsoft Academic Search

    Ralph Kurt; Ayatollah Karimi; Volker Hoffmann

    2001-01-01

    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

  3. Design and characterization of carbon nanotube nanocomposites

    Microsoft Academic Search

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

    2003-01-01

    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

  4. Autonomous propulsion of carbon nanotubes powered by a multienzyme ensemble.

    PubMed

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

    2008-04-01

    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

  5. Local Electronic Structure of Single-Walled Carbon Nanotubes from

    E-print Network

    Bockrath, Marc

    reflects its fundamental properties. Measurements of electronic com- pressibility, which is determinedLocal Electronic Structure of Single-Walled Carbon Nanotubes from Electrostatic Force Microscopy, thereby coupling the cantilever's mechanical oscillations to the nanotube's local electronic properties

  6. Flame synthesis of carbon nanotubes and metallic nanomaterials

    E-print Network

    Height, Murray John, 1975-

    2003-01-01

    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 ...

  7. Energy Carrier Transport In Surface-Modified Carbon Nanotubes

    E-print Network

    Ryu, Yeontack

    2012-11-30

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

  8. Multifunctional and recollectable carbon nanotube ponytails for water purification.

    PubMed

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

    2014-06-25

    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

  9. Electronic Properties of Carbon Nanotubes and Applications

    Microsoft Academic Search

    Mildred S. Dresselhaus

    \\u000a A brief overview will be given of the remarkable structural and electronic properties of carbon nanotubes, which are tiny\\u000a structures of molecular dimensions in the form of hollow cylinders with about 20 carbon atoms around the circumference of\\u000a the cylinders and microns in length. Unusual properties follow as a consequence of quantum mechanical phenomena associated\\u000a with this one-dimensional system. The

  10. Thursday, March 9 85 Magnetic Properties of Carbon Nanofoam PTh

    E-print Network

    Maruyama, Shigeo

    Thursday, March 9 85 Magnetic Properties of Carbon Nanofoam PTh 7D. Ar`eon, P. Cevc, Z. Jagli have been observed. NOVEL ROUTE TO (BIO)-POLYMER NANOTUBE COMPOSITES PTh 8A.I. Minett1 , J.N. Coleman2 OF VARIOUS (N, M) NANOTUBES BY CROSS- PTh 9POLARIZED ABSORPTION Yuhei Miyauchi, Mototeru Oba, and Shigeo

  11. Excitation transfer and luminescence in porphyrin-carbon nanotube complexes

    E-print Network

    Magadur, G; Alain-Rizzo, V; Voisin, C; Roussignol, Ph; Deleporte, E; Delaire, J A

    2007-01-01

    Functionalization of carbon nanotubes with hydrosoluble porphyrins (TPPS) is achieved by "$\\pi$-stacking". The porphyrin/nanotube interaction is studied by means of optical absorption, photoluminescence and photoluminescence excitation spectroscopies. The main absorption line of the porphyrins adsorbed on nanotubes exhibits a 120 meV red shift, which we ascribe to a flattening of the molecule in order to optimize $\\pi-\\pi$ interactions. The porphyrin-nanotube complex shows a strong quenching of the TPPS emission while the photoluminescence intensity of the nanotubes is enhanced when the excitation laser is in resonance with the porphyrin absorption band. This reveals an efficient excitation transfer from the TPPS to the carbon nanotube.

  12. Performance comparison between carbon nanotube and copper interconnects for GSI

    Microsoft Academic Search

    Azad Naeemi; Reza Sarvari; James D. Meindl

    2004-01-01

    The performances of minimum-size copper and carbon nanotube interconnects are compared for various ITRS generations. Results offer important guidance regarding the nature of carbon nanotube technology development needed for improving interconnect performance. Since wave propagation is slow in a single nanotube, nanotube-bundles with larger wave speeds must be used. At the 45nm node (year 2010), the performance enhancement that can

  13. Effect of nanotube-nanotube coupling on the radial breathing mode of carbon nanotubes Rajay Kumar, Mehmet Aykol, and Stephen B. Cronin*

    E-print Network

    Cronin, Steve

    an increased radial breathing mode RBM frequency for solubilized nanotubes as compared to nanotube bundlesEffect of nanotube-nanotube coupling on the radial breathing mode of carbon nanotubes Rajay Kumar 2008; published 28 October 2008 We study the radial breathing mode RBM of resonant single walled carbon

  14. Carbon nanotubes on a spider silk scaffold

    PubMed Central

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

    2013-01-01

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

  15. Large-scale modeling of carbon-nanotube composites by a fast multipole boundary element method

    E-print Network

    Liu, Yijun

    Large-scale modeling of carbon-nanotube composites by a fast multipole boundary element method; Fast boundary element method 1. Introduction Carbon nanotubes possess extremely high stiffness November 2004 Abstract Carbon nanotubes (CNTs) exhibit extremely high stiffness and strength

  16. CONDENSED MATTER: ELECTRONICSTRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Theoretical Study on the Propagation of Acoustic Phonon Modes in Single-Wall Carbon Nanotubes by Different Potential Models

    Microsoft Academic Search

    Bing Cao; Wei Zhang; Ping Huai; Zhi-Yuan Zhu

    2009-01-01

    Propagation of a heat pulse in (10,0) zig-zag carbon nanotubes, modeled by the Brenner-II and Tersoff bond-order potentials, respectively, is investigated using a molecular dynamics simulation. The longitudinal acoustic mode, twisting phonon mode, and second sound waves are observed in the simulation. The time variations of speed and intensity of the above three phonon modes are in good agreement with

  17. Electronic transport in single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Antonov, Radoslav Dimitrov

    1999-12-01

    We have studied the electronic properties of single-wall carbon nanotubes (SWNTs) from room temperature down to 10mK by performing electronic transport spectroscopy measurements on individual single-wall nanotubes, nanotube ropes and untreated bulk SWNT material. Transport in metallic single-wall nanotubes at dilution refrigerator temperatures occurs via the resonant tunneling of electrons through discrete molecular orbitals of the tubes. The discrete energy level splitting in a 0.8mum long nanotube was roughly 1.2meV, which agrees with the 1meV estimate for the energy level splitting. Zeeman splitting of a single particle level was observed when a magnetic field was applied perpendicular to the tube, which yielded g = 1.8 for the electronic g-factor in a nanotube. Due to the small capacitance of the nanotube, the conductance at low bias voltages is suppressed by the Coulomb blockade. Surprisingly, the differential conductance of the tube shows a pattern of single electron charging that suggests the tube behaves as a couple of quantum dots in series. A numerical simulation, based on a model of a tube with three levels, reproduces some prominent features of the data. Electrons in a nanotube occupy 1D subbands. Sharp van Hove singularities in the density of states are expected at the band edges of the 1D modes and were observed as steps in the current-voltage characteristics of a semiconducting nanotube at 77K. By varying an external gate voltage we electrostatically doped the tube and controllably populated its subbands. The IV characteristics of a segment of the nanotube covered in part by an impurity were highly asymmetric. This was in sharp contrast to the symmetric IVs observed for a clean segment of the same tube. A simple band model, in which the impurity acts as a local charge dopant, can account for the diodic behavior of the tube. Early experiments on "mats" of bulk SWNT material revealed that low temperature transport in the bulk occurs via three dimensional (3D) variable range hopping of electrons between localized states. A typical characteristic temperature T0 for the material is 110 K. The bulk samples also exhibited a negative magneto-resistance, which indicates that transport in the mats is partly phase coherent. We used 3D weak localization theory to fit the data and obtained l ? = 1500A for the phase coherence length at 100mK .

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

    PubMed Central

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

    2015-01-01

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

  19. Diffusion through Carbon Nanotube Semipermeable membranes

    SciTech Connect

    Bakajin, O

    2006-02-13

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

  20. Energetic and magnetic properties of transition-metal nanowire encapsulated BxCyNz composite nanotubes

    Microsoft Academic Search

    G. W. Peng; A. C. H. Huan; Y. P. Feng

    2006-01-01

    We present a comparative study on the structural, energetic, and magnetic properties of carbon and BxCyNz composite single-walled nanotubes filled with transition-metal (TM) nanowires using first-principles calculations. It was found that interaction between the nanotube and nanowire weakens the magnetism of the nanowire. TM\\/BC3 was found exceptionally stable and its formation is exothermic. The resulting hybrid structure, however, has the

  1. Energetic and magnetic properties of transition-metal nanowire encapsulated BxCyNz composite nanotubes

    Microsoft Academic Search

    G. W. Peng; A. C. H. Huan; Y. P. Feng

    2006-01-01

    We present a comparative study on the structural, energetic, and magnetic properties of carbon and BxCyNz composite single-walled nanotubes filled with transition-metal (TM) nanowires using first-principles calculations. It was found that interaction between the nanotube and nanowire weakens the magnetism of the nanowire. TM?BC3 was found exceptionally stable and its formation is exothermic. The resulting hybrid structure, however, has the

  2. Carbon Nanotubes: Measuring Dispersion and Length

    SciTech Connect

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

    2011-03-01

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

  3. Carbon Nanotubes: Synthesis and Characterization

    Microsoft Academic Search

    Yamini Yadav; Vindhya Kunduru; Shalini Prasad

    Carbon can form various types of structurally different frameworks due to the ability of the carbon atoms to form different species of valence bonds. The extremely organized coagulation process of carbon molecules resulting in the formation of the perfectly symmetric fullerene molecule despite the chaotic environment of the carbon arc is truly fascinating. Although many formation theories for the buckyball

  4. Permalloy-based carbon nanotube spin-valve

    NASA Astrophysics Data System (ADS)

    Aurich, H.; Baumgartner, A.; Freitag, F.; Eichler, A.; Trbovic, J.; Schönenberger, C.

    2010-10-01

    In this paper we demonstrate that permalloy (Py), a widely used Ni/Fe alloy, forms contacts to carbon nanotubes (CNTs) that meet the requirements for the injection and detection of spin-polarized currents in carbon-based spintronic devices. We establish the material quality and magnetization properties of Py strips in the shape of suitable electrical contacts and find a sharp magnetization switching tunable by geometry in the anisotropic magnetoresistance (AMR) of a single strip at cryogenic temperatures. In addition, we show that Py contacts couple strongly to CNTs, comparable to Pd contacts, thereby forming CNT quantum dots at low temperatures. These results form the basis for a Py-based CNT spin-valve exhibiting very sharp resistance switchings in the tunneling magnetoresistance, which directly correspond to the magnetization reversals in the individual contacts observed in AMR experiments.

  5. Carbon nanotube formation by laser direct writing

    SciTech Connect

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

    2008-07-14

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

  6. A Structural Transition of Carbon Nanotubes?

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  7. Osmotic water transport through carbon nanotube membranes

    PubMed Central

    Kalra, Amrit; Garde, Shekhar; Hummer, Gerhard

    2003-01-01

    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

  8. Mesoscale mechanics of twisting carbon nanotube yarns.

    PubMed

    Mirzaeifar, Reza; Qin, Zhao; Buehler, Markus J

    2015-03-12

    Fabricating continuous macroscopic carbon nanotube (CNT) yarns with mechanical properties close to individual CNTs remains a major challenge. Spinning CNT fibers and ribbons for enhancing the weak interactions between the nanotubes is a simple and efficient method for fabricating high-strength and tough continuous yarns. Here we investigate the mesoscale mechanics of twisting CNT yarns using full atomistic and coarse grained molecular dynamics simulations, considering concurrent mechanisms at multiple length-scales. To investigate the mechanical response of such a complex structure without losing insights into the molecular mechanism, we applied a multiscale strategy. The full atomistic results are used for training a coarse grained model for studying larger systems consisting of several CNTs. The mesoscopic model parameters are updated as a function of the twist angle, based on the full atomistic results, in order to incorporate the atomistic scale deformation mechanisms in larger scale simulations. By bridging across two length scales, our model is capable of accurately predicting the mechanical behavior of twisted yarns while the atomistic level deformations in individual nanotubes are integrated into the model by updating the parameters. Our results focused on studying a bundle of close packed nanotubes provide novel mechanistic insights into the spinning of CNTs. Our simulations reveal how twisting a bundle of CNTs improves the shear interaction between the nanotubes up to a certain level due to increasing the interaction surface. Furthermore, twisting the bundle weakens the intertube interactions due to excessive deformation in the cross sections of individual CNTs in the bundle. PMID:25732328

  9. Process for derivatizing carbon nanotubes with diazonium species

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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##.

  10. Synthesis and characterization of carbon nanoribbons and single crystal iron filled carbon nanotubes

    SciTech Connect

    Mahanandia, P. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India)], E-mail: pitam@physics.iisc.ernet.in; Nanda, K.K. [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Prasad, V.; Subramanyam, S.V. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India)

    2008-12-01

    Carbon nanoribbons and single crystal iron filled multiwall carbon nanotubes (MWCNTs) have been synthesized by simple pyrolysis technique. SEM investigation shows that the material consist mainly carbon nanoribbons and carbon nanotubes (CNTs). X-ray diffraction (XRD), electron energy loss spectroscopy (EELS), electron energy dispersive X-ray (EDX), transmission electron miscroscopy (TEM) and highresolution transmission electron miscroscopy (HRTEM) studies reveal carbon nanotubes are filled with {alpha}-Fe. Closer inspection of HRTEM images indicated that the bcc structure {alpha}-Fe nanowires are monocrystalline and Fe (1 1 0) plane is indeed perpendicular to the G (0 0 2) plane, whereas orientation of (0 0 2) lattice planes of carbon nanoribbon is perpendicular to the axis of growth. Magnetic properties studied by superconducting quantum interference device (SQUID) at 300 K and 10 K exhibited coercivity of 1037 Oe and 2023 Oe. The large coercitivity is strongly attributed to the small size monocrystalline single phase {alpha}-Fe, single domain nature of the encapsulated Fe crystal, magnetocrystalline shape anisotropy and ferromagnetic behaviour of localized states at the edges of the carbon nanoribbons.

  11. Structure and energetics of carbon nanotube ropes Zejian Liu a

    E-print Network

    Qin, Lu-Chang

    microscopic image simulations of an energetically-stable rope composed of seven sin- gle-walled carbon single-walled carbon nanotubes are preferred in building molecular electronic circuits [7,8], while car materials. Single-walled carbon nanotubes, produced by the popular techniques such as electric arc

  12. Production of carbon nanotubes by the solar route

    Microsoft Academic Search

    T. Guillard; S. Cetout; L. Alvarez; J. L. Sauvajol; E. Anglaret; P. Bernier; G. Flamant; D. Laplaze

    1999-01-01

    The high intensity of concentrated solar radiation obtained with the Odeillo (France) solar furnace facilities can be used to produce carbon nanotubes by direct vaporization of carbon bi-metal targets under inert gas atmosphere. Electron microscope pictures and Raman spectra show that the structure of the produced carbon nanotubes is likely to depend on experimental conditions and that the growth of

  13. Single Crystals of Single-Walled Carbon Nanotubes Formed by

    E-print Network

    Gimzewski, James

    -assembly of single crystals of single-walled carbon nano- tubes (SWCNTs) using thermolysis of nano of carbon nanotube fabrication is to form large uniform and ordered nano- and microstructuresSingle Crystals of Single-Walled Carbon Nanotubes Formed by Self-Assembly R. R. Schlittler,1 J. W

  14. Enhanced Cellular Activation with Single Walled Carbon Nanotube Bundles

    E-print Network

    Fahmy, Tarek

    focused on new methods of biochemical functionalization of carbon nano- tubes using various proteinsEnhanced 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

  15. Graphene\\/Carbon Nanotube Cross-Junction Devices

    Microsoft Academic Search

    Melina Blees; Xiaodong Xu; Arend van der Zande; Zhaohui Zhong; Nathan Gabor; Phi Pham; Paul McEuen

    2010-01-01

    We have built crossed carbon nanotube\\/graphene junctions from CVD graphene and aligned arrays of carbon nanotubes. Large-area single-layer graphene was grown on a copper film and transferred to silicon oxide, then lithographically patterned and electrically contacted. Highly aligned arrays of single-walled carbon nanotubes were CVD-grown on quartz and transferred to complete the devices. We probed these new geometries using electrical

  16. Micro-Raman spectroscopy of isolated single wall carbon nanotube

    Microsoft Academic Search

    R. Saito; A. Jorio; A. G. Souza Filho; J. H. Hafner; C. M. Lieber; M. Hunter; T. McClure; M. A. Pimenta; A. M. Rao; G. Dresselhaus; M. S. Dresselhaus

    2001-01-01

    Micro-Raman spectroscopy of an isolated single wall carbon nanotube is overviewed in connection with the recent observation of (1) the chirality-dependent G-band Raman intensity, (2) BWF line analysis and (3) D-band feature of an individual single wall carbon nanotube. The localized phonons appeared around a point defect of carbon nanotube might be relevant to D-band intensity. .

  17. Chemically Functionalized Carbon Nanotubes as Substrates for Neuronal Growth.

    PubMed

    Hu, Hui; Ni, Yingchun; Montana, Vedrana; Haddon, Robert C; Parpura, Vladimir

    2004-03-01

    We report the use of chemically modified carbon nanotubes as a substrate for cultured neurons. The morphological features of neurons that directly reflect their potential capability in synaptic transmission are characterized. The chemical properties of carbon nanotubes are systematically varied by attaching different functional groups that confer known characteristics to the substrate. By manipulating the charge carried by functionalized carbon nanotubes we are able to control the outgrowth and branching pattern of neuronal processes. PMID:21394241

  18. Investigation of the Plastic Deformation and Fracture of Carbon Nanotubes

    Microsoft Academic Search

    K. J. Ma; C. L. Chao; C. W. Tang; K. H. Chen; L. C. Chen

    Carbon nanotubes have demonstrated fascinating mechanical properties. The tensile strength as well as plastic deformation\\u000a and fracture behaviour of carbon nanotubes, probably more important for material applications, are still lacking experimentally.\\u000a It is too small to be manipulated with conventional tensile test facilities. We have developed a technique with which deformation\\u000a and fracture behaviour of carbon nanotubes under a tensile

  19. Electrostatic sensing and electrochemistry with single carbon nanotubes

    Microsoft Academic Search

    I. Heller

    2009-01-01

    This thesis describes the experimental study of devices based on single carbon nanotubes in the context of (bio)sensing in aqueous solutions. Carbon nanotubes are cylindrical molecules of sp2- carbon, about one nanometer in diameter and typically several micrometers long, which have semiconducting or metallic electronic properties. Nanotube devices can interact both electrostatically and electrochemically with the solution and the (bio)molecules

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

    E-print Network

    Yazzie, Kyle E

    2008-01-01

    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 ...

  1. Continuous Growth of Vertically Aligned Carbon Nanotubes Forests

    E-print Network

    Guzman de Villoria, Roberto

    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 ...

  2. Towards structural health monitoring in carbon nanotube reinforced composites

    E-print Network

    Wang, Wennie

    2013-01-01

    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 ...

  3. Carbon Nanotube Array Dynamics In Immersion And Drying

    NASA Astrophysics Data System (ADS)

    Sansom, Elijah B.; Noca, Flavio; Chen, Fei; Gharib, Morteza; Hoenk, Michael; Kowalczyk, Robert

    2002-11-01

    A solid understanding of interactions between carbon nanotubes and water is necessary for the development of carbon nanotube based fluidic devices such as acoustic sensors, single molecule level resonant sensors, force actuators, and biomolecular analyzers. Our results show that interfacial tension, hydrophobicity, and carbon nanotube bending dynamics are potentially all involved in such a system. Semi-ordered dense arrays of multi-walled carbon nanotubes grown by plasma enhanced chemical vapor deposition (PECVD) were treated with various solutions, including surfactants such as Sodium Dodecyl Sulfate (SDS), bacteria, and several types of microspheres. Structural rearrangements were determined by electron and optical microscopy.

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

    E-print Network

    García, Enrique J

    2006-01-01

    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 ...

  5. Development of Carbon Nanotube-Based Sensors—A Review

    Microsoft Academic Search

    Benjamin Mahar; Cosmin Laslau; Ronnie Yip; Yu Sun

    2007-01-01

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

  6. Gas Adsorption on Heterogeneous Single-Walled Carbon Nanotube Bundles

    Microsoft Academic Search

    Wei Shi; J. Karl Johnson

    2003-01-01

    Optimization of carbon nanotube bundles containing a distribution of nanotube diameters always gives structures with packing defects that form relatively large interstitial channels. Experimental data for CH4, Ar, and Xe adsorption are compared with simulations. Low coverage experimental isosteric heats are in excellent agreement with simulations of gases adsorbing into interstitial channels of defective nanotube bundles, whereas adsorption onto perfect

  7. Analytical approach to optical absorption in carbon nanotubes

    Microsoft Academic Search

    Ermin Malic; Matthias Hirtschulz; Frank Milde; Andreas Knorr; Stephanie Reich

    2006-01-01

    We derive an analytic expression for the optical matrix elements of carbon nanotubes and calculate their optical absorption spectra within the tight-binding approximation. For zigzag nanotubes we present an analytical result for the absorption coefficient. Metallic nanotubes have an optical band gap regardless of their chiral angle. The optical absorption intensity increases by up to 10% from zigzag to armchair

  8. Transparent and Electrically Conductive Carbon Nanotube-Polymer Nanocomposite Materials for Electrostatic Charge Dissipation

    NASA Technical Reports Server (NTRS)

    Dervishi, E.; Biris, A. S.; Biris, A. R.; Lupu, D.; Trigwell, S.; Miller, D. W.; Schmitt, T.; Buzatu, D. A.; Wilkes, J. G.

    2006-01-01

    In recent years, nanocomposite materials have been extensively studied because of their superior electrical, magnetic, and optical properties and large number of possible applications that range from nano-electronics, specialty coatings, electromagnetic shielding, and drug delivery. The aim of the present work is to study the electrical and optical properties of carbon nanotube(CNT)-polymer nanocomposite materials for electrostatic charge dissipation. Single and multi-wall carbon nanotubes were grown by catalytic chemical vapor deposition (CCVD) on metal/metal oxide catalytic systems using acetylene or other hydrocarbon feedstocks. After the purification process, in which amorphous carbon and non-carbon impurities were removed, the nanotubes were functionalized with carboxylic acid groups in order to achieve a good dispersion in water and various other solvents. The carbon nanostructures were analyzed, both before and after functionalization by several analytical techniques, including microscopy, Raman spectroscopy, and X-Ray photoelectron spectroscopy. Solvent dispersed nanotubes were mixed (1 to 7 wt %) into acrylic polymers by sonication and allowed to dry into 25 micron thick films. The electrical and optical properties of the films were analyzed as a function of the nanotubes' concentration. A reduction in electrical resistivity, up to six orders of magnitude, was measured as the nanotubes' concentration in the polymeric films increased, while optical transparency remained 85 % or higher relative to acrylic films without nanotubes.

  9. Multifunctional Superhydrophobic Polymer/Carbon Nanocomposites: Graphene, Carbon Nanotubes, or Carbon Black?

    E-print Network

    Daraio, Chiara

    and macro scales4 and textiles5 to name a few. Superhydrophobicity provides a pathway toward protect- ingMultifunctional Superhydrophobic Polymer/Carbon Nanocomposites: Graphene, Carbon Nanotubes, Switzerland *S Supporting Information ABSTRACT: Superhydrophobic surfaces resisting water penetration

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

    E-print Network

    Gaddamanugu, Dhatri

    2010-07-14

    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...

  11. Aqueous nanosilica dispersants for carbon nanotube.

    PubMed

    Matsuda, Takafumi; Minami, Daiki; Khoerunnisa, Fitri; Sunaga, Motoo; Nakamura, Masahiro; Utsumi, Shigenori; Itoh, Tsutomu; Fujimori, Toshihiko; Hayashi, Takuya; Hattori, Yoshiyuki; Endo, Morinobu; Isobe, Hiroshi; Onodera, Hiroshi; Kaneko, Katsumi

    2015-03-17

    Nanosilicas can disperse single-wall carbon nanotube (SWCNT) in aqueous solution efficiently; SWCNTs are stably dispersed in aqueous media for more than 6 months. The SWCNT dispersing solution with nanosilica can produce highly conductive transparent films which satisfy the requirements for application to touch panels. Even multiwall carbon nanotube can be dispersed easily in aqueous solution. The highly stable dispersion of SWCNTs in the presence of nanosilica is associated with charge transfer interaction which generates effective charges on the SWCNT particles, giving rise to electrostatic repulsion between the SWCNTs in the aqueous solution. Adhesion of charged nanosilicas on SWCNTs in the aqueous solution and a marked depression of the S11 peak of optical absorption spectrum of the SWCNT with nanosilicas suggest charge transfer interaction of nanosilicas with SWCNT. Thus-formed isolated SWCNTs are fixed on the flexible three-dimensional silica jelly structure in the aqueous solution, leading to the uniform and stable dispersion of SWCNTs. PMID:25706991

  12. Density controlled carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng F. (Newton, MA); Tu, Yi (Belmont, MA)

    2008-12-16

    CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.

  13. Spontaneous exciton dissociation in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yoshida, Masahiro; Kumamoto, Yusuke; Ishii, Akihiro; Yokoyama, Akio; Shimada, Takashi; Kato, Yuichiro K.

    2014-03-01

    Simultaneous photoluminescence and photocurrent measurements on individual single-walled carbon nanotubes reveal spontaneous dissociation of excitons into free electron-hole pairs.[2] A simple model is constructed to consistently describe the excitation power and voltage dependence of the photoluminescence and photocurrent. Using this model, we find that a significant fraction of excitons are dissociating before recombination. Furthermore, the combination of optical and electrical signals also allows for extraction of the absorption cross section and the oscillator strength. Our observations explain the reasons for photoconductivity measurements in single-walled carbon nanotubes being straightforward despite the large exciton binding energies. Work supported by KAKENHI, SCOPE, KDDI Foundation, and the Photon Frontier Network Program of MEXT, Japan.

  14. Carbon nanotube alignment in a thermosetting resin

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  15. Fabrication and Characterization of Suspended Carbon Nanotube Devices in Liquid

    SciTech Connect

    Artyukhin, A; Stadermann, M; Stroeve, P; Bakajin, O; Noy, A

    2006-10-30

    Suspended carbon nanotube devices are a promising platform for future bio-electronic applications. Suspended carbon nanotube transistors have been previously fabricated in air; however all previous attempts to bring them into liquid failed. We analyze forces acting on the suspended nanotube devices during immersion into liquids and during device operation and show that surface tension forces acting on the suspended nanotubes during transfer into the liquid phase are responsible for the nanotube damage. We have developed a new strategy that circumvents these limitations by coating suspended nanotubes with a rigid inorganic shell in the gas phase. The coating reinforces the nanotubes and allows them to survive transfer through the interface. Subsequent removal of the coating in the solution phase restores pristine suspended nanotubes. We demonstrate that devices fabricated using this technique preserve their original electrical characteristics.

  16. Magnetic silica nanotubes: synthesis, drug release, and feasibility for magnetic hyperthermia.

    PubMed

    Chen, Xuecheng; Klingeler, Rüdiger; Kath, Matthias; El Gendy, Ahmed A; Cendrowski, Krzysztof; Kalenczuk, Ryszard J; Borowiak-Palen, Ewa

    2012-04-01

    A new kind of silica nanotube with incorporated ?-Fe(2)O(3) nanoparticles has been successfully prepared through sol-gel processes. Hematite particles supported on carbon nanotubes served as templates for the fabrication of the magnetic silica nanotubes. The obtained nanostructures consisting of magnetic Fe(2)O(3) nanoparticles protected by a silica shell were fully characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), N(2) sorption and desorption, and magnetization studies. The hollow inner space and the magnetic functionalization render the material promising for applications in biology and medicine. This is underlined by studies in alternating magnetic fields which show a significant heating effect, i.e., the feasibility for applications in hyperthermia therapies. In addition, the material exhibits enhanced drug-loading capacity which is demonstrated by loading with rhodamine B molecules as drugs and corresponding release experiments. The results show that magnetic silica nanotubes can be straightforwardly synthesized and have a great potential as a multifunctional drug carrier system. PMID:22486255

  17. SAW Gas sensors with carbon nanotubes films

    Microsoft Academic Search

    M. Penza; R. Rossi; M. Alvisi; P. Aversa; G. Cassano; D. Suriano; M. Benetti; D. Cannata; F. Di Pietrantonio; E. Verona

    2008-01-01

    A surface acoustic wave (SAW) gas sensor with multiwalled carbon nanotubes (CNTs) layered films as chemically interactive nanomaterial is presented. A SAW two-port resonator integrated on ST-cut quartz substrate has been functionally characterized as oscillator in dual differential mode at the resonant frequency of 433.92 and 915 MHz. Nanocomposite layers based on filler of CNTs, grown by RF-plasma enhanced chemical

  18. Carbon nanotube based spectrum infrared detectors

    Microsoft Academic Search

    Ning Xi; Harold Szu; James Buss; Ingham Mack

    2005-01-01

    Carbon nanotubes (CNT) have a potential to be efficient infrared (IR) detection materials due to their unique electronic properties. The ballistic electronic transport property makes the noise equivalent temperature difference smaller compared to other semi-conducting materials. By overlaying CNT-based mid-IR (3-5mu) detectors on a long-wave IR (8-15mu) focal plane array, the mid-IR detector causes no filters loss. In order to

  19. Multiwalled carbon nanotube: Luttinger versus Fermi liquid

    Microsoft Academic Search

    R. Tarkiainen; M. Ahlskog; J. Penttilä; L. Roschier; P. Hakonen; M. Paalanen; E. Sonin

    2001-01-01

    We have measured IV curves of multiwalled carbon nanotubes using end contacts. At low voltages, the tunneling conductance obeys non-Ohmic power law, which is predicted both by the Luttinger liquid and the environment-quantum-fluctuation theories. However, at higher voltages we observe a crossover to Ohm's law with a Coulomb-blockade offset, which agrees with the environment-quantum-fluctuation theory, but cannot be explained by

  20. Luttinger Liquid Behavior in Multiwall Carbon Nanotubes

    Microsoft Academic Search

    Reinhold Egger; A. Bachtold; M. Fuhrer; M. Bockrath; D. Cobden; P. McEuen

    1999-01-01

    The low-energy theory for multiwall carbon nanotubes including the long-ranged Coulomb interactions, internal screening effects, and single-electron hopping between graphite shells is derived and analyzed by bosonization methods. Characteristic Luttinger liquid power laws are found for the tunneling density of states, with exponents approaching their Fermi liquid value only very slowly as the number of conducting shells increases. With minor

  1. Carbon nanotube-polymer nanocomposite infrared sensor.

    PubMed

    Pradhan, Basudev; Setyowati, Kristina; Liu, Haiying; Waldeck, David H; Chen, Jian

    2008-04-01

    The infrared photoresponse in the electrical conductivity of single-walled carbon nanotubes (SWNTs) is dramatically enhanced by embedding SWNTs in an electrically and thermally insulating polymer matrix. The conductivity change in a 5 wt % SWNT-polycarbonate nanocomposite is significant (4.26%) and sharp upon infrared illumination in the air at room temperature. While the thermal effect predominates in the infrared photoresponse of a pure SWNT film, the photoeffect predominates in the infrared photoresponse of SWNT-polycarbonate nanocomposites. PMID:18333623

  2. Light Harvesting Single Wall Carbon Nanotube Hybrids

    Microsoft Academic Search

    Benjamin Baker; Tae-Gon Cha; M. Dane Sauffer; Yujun Wu; Jong Hyun Choi

    2010-01-01

    Due to extraordinary electron accepting and conductivity properties, single wall carbon nanotubes (SWNT) are explored as molecular wires in light harvesting cells. Here SWNT are employed as acceptors of photo-excited charge\\/energy in self-assembling aqueous soluble nanohybrids. DNA oligonucleotides and functionalized pyrene moieties are used as surfactants to solubilize an ensemble of individually suspended SWNT. Water-soluble porphyrins, chlorophyll-like molecules with strong

  3. Octagonal Defects at Carbon Nanotube Junctions

    PubMed Central

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

    2013-01-01

    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

  4. Carbon nanotube-reinforced polyurethane composite fibers

    Microsoft Academic Search

    Wei Chen; Xiaoming Tao; Yuyang Liu

    2006-01-01

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

  5. Reassessing molecular sieving by kinked carbon nanotubes

    Microsoft Academic Search

    Zhongqiang Zhang; Hongwu Zhang; Lei Wang; Jianning Ding; Jinbao Wang; Yonggang Zheng; Hongfei Ye; Zhen Liu; Guanggui Cheng; Zhiyong Ling

    2011-01-01

    Based on molecular dynamics simulations for the transport of pure nitrogen (N2), oxygen (O2) and their mixture in kinked single-walled carbon nanotubes (SWCNTs), molecular sieving by the kinked model of SWCNTs is presented. The influences of gas pressure, temperature and the component ratio of N2 in the mixture on gas separation are investigated. Considering the tradeoff between the permeability and

  6. Carbon Nanotubes as Electrical Interfaces with Neurons

    Microsoft Academic Search

    William Lee; Vladimir Parpura

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

  7. Order in vertically aligned carbon nanotube arrays

    SciTech Connect

    Wang, Hsin [ORNL; Xu, Z [Michigan State University, East Lansing; Eres, Gyula [ORNL

    2006-01-01

    We report the direct measurements on the bulk morphology of vertically aligned multiwalled carbon nanotube (CNT) arrays using small angle neutron scattering (SANS). SANS measurements at different heights of CNT arrays corresponding to different stages of the growth reveal increasing alignment order along the thickness and two distinctly different CNT morphologies. The observations suggest that the evolution of the macroscopic CNT morphologies be driven by competing collective growth and spatial constraints.

  8. Carbon nanotube and polyaniline composite actuators

    Microsoft Academic Search

    May Tahhan; Van-Tan Truong; Geoffrey M. Spinks; Gordon G. Wallace

    2003-01-01

    The actuation of a single-wall carbon nanotube (CNT) mat, an electrically conducting polyaniline (PAn) film and a composite of these two materials has been investigated in NaNO3 (1 M), NaCl (1 and 3 M) and HCl (1 M) solutions. The expansion and contraction patterns of the PAn, CNT and CNT\\/PAn samples are similar in these solutions. Fabrication of the CNT\\/PAn

  9. Computational nanotechnology with carbon nanotubes and fullerenes

    Microsoft Academic Search

    DEEPAK SRIVASTAVA; MADHU MENON; Kyeongjae Cho

    2001-01-01

    The authors envision computational nanotechnology's role in developing the next generation of multifunctional materials and molecular-scale electronic and computing devices, sensors, actuators, and machines. They briefly review computational techniques and provide a few recent examples derived from computer simulations of carbon nanotube-based molecular nanotechnology. The four core areas are: molecular-scale, ultralightweight, extremely strong, functional or smart materials; molecular-scale or nanoscale

  10. Synthesis of PbI(2) single-layered inorganic nanotubes encapsulated within carbon nanotubes.

    PubMed

    Cabana, Laura; Ballesteros, Belén; Batista, Eudar; Magén, César; Arenal, Raúl; Oró-Solé, Judith; Rurali, Riccardo; Tobias, Gerard

    2014-04-01

    The template assisted growth of single-layered inorganic nanotubes is reported. Single-crystalline lead iodide single-layered nanotubes have been prepared using the inner cavities of carbon nanotubes as hosting templates. The diameter of the resulting inorganic nanotubes is merely dependent on the diameter of the host. This facile method is highly versatile opening up new horizons in the preparation of single-layered nanostructures. PMID:24339133

  11. Carbon nanotubes - the promising adsorbent in wastewater treatment

    NASA Astrophysics Data System (ADS)

    Li, Y. H.; Zhao, Y. M.; Hu, W. B.; Ahmad, I.; Zhu, Y. Q.; Peng, X. J.; Luan, Z. K.

    2007-03-01

    Carbon materials are a class of significant and widely used engineering adsorbent. As a new member of the carbon family, carbon nanotubes have exhibited great potentials in applications as composite reinforcements, field emitters for flat panel display, sensors, energy storage and energy conversion devices, and catalysts support phases, because of their extraordinary mechanical, electrical, thermal and structural properties. In particular, the large specific surface areas, as well as the high chemical and thermal stabilities, make carbon nanotubes an attractive adsorbent in wastewater treatment. The adsorption properties of the carbon nanotubes to a series of toxic agents, such as lead, cadmium and 1, 2-dichlorobenzene have been studied and the results show that carbon nanotubes are excellent and effective adsorbent for eliminating these harmful media in water. The effects of the morphologies and the surface status on the carbon nanotube adsorption capacities are also discussed.

  12. Optical modulation of single walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Strano, Michael S.

    2007-03-01

    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.

  13. TOPICAL REVIEW: Carbon nanotubes for biological and biomedical applications

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

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

  14. Carbon nanotubes linked with pitavastatin: synthesis and characterisation.

    PubMed

    Borowiak-Palen, E; Skupin, P; Kruszynska, M; Sobotta, L; Mielcarek, J

    2011-04-01

    The paper presents a study on functionalisation of multi-walled carbon nanotubes in the area of lattice defects and an attempt to bind the nanotubes with pitavastatin. Carbon nanotubes were synthesised by alcohol-chemical vapour deposition in the presence of the catalyst Fe-Co/MgO. The nanotubes were purified and the product was subjected to chemical functionalisation. Functional groups were introduced in the reaction of the purified nanotubes with thionyl chloride to obtain acidic chlorides linked to pitavastatin. The properties and structure of the nanotubes were analysed by FT-IR and Raman spectroscopies, transmission electron microscopy and liquid chromatography coupled with mass spectrometry. Photochemical stability of pitavastatin linked with carbon nanotubes has been found to be increased. PMID:21360122

  15. Carbon nanotube network-silicon oxide non-volatile switches.

    PubMed

    Liao, Albert D; Araujo, Paulo T; Xu, Runjie; Dresselhaus, Mildred S

    2014-01-01

    The integration of carbon nanotubes with silicon is important for their incorporation into next-generation nano-electronics. Here we demonstrate a non-volatile switch that utilizes carbon nanotube networks to electrically contact a conductive nanocrystal silicon filament in silicon dioxide. We form this device by biasing a nanotube network until it physically breaks in vacuum, creating the conductive silicon filament connected across a small nano-gap. From Raman spectroscopy, we observe coalescence of nanotubes during breakdown, which stabilizes the system to form very small gaps in the network~15?nm. We report that carbon nanotubes themselves are involved in switching the device to a high resistive state. Calculations reveal that this switching event occurs at ~600?°C, the temperature associated with the oxidation of nanotubes. Therefore, we propose that, in switching to a resistive state, the nanotube oxidizes by extracting oxygen from the substrate. PMID:25482919

  16. Carbon nanotubes as ultrahigh quality factor mechanical resonators.

    PubMed

    Hüttel, Andreas K; Steele, Gary A; Witkamp, Benoit; Poot, Menno; Kouwenhoven, Leo P; van der Zant, Herre S J

    2009-07-01

    We have observed the transversal vibration mode of suspended carbon nanotubes at millikelvin temperatures by measuring the single-electron tunneling current. The suspended nanotubes are actuated contact-free by the radio frequency electric field of a nearby antenna; the mechanical resonance is detected in the time-averaged current through the nanotube. Sharp, gate-tunable resonances due to the bending mode of the nanotube are observed, combining resonance frequencies of up to nu(0) = 350 MHz with quality factors above Q = 10(5), much higher than previously reported results on suspended carbon nanotube resonators. The measured magnitude and temperature dependence of the Q factor shows a remarkable agreement with the intrinsic damping predicted for a suspended carbon nanotube. By adjusting the radio frequency power on the antenna, we find that the nanotube resonator can easily be driven into the nonlinear regime. PMID:19492820

  17. Carbon Nanotubes as Ultrahigh Quality Factor Mechanical Resonators

    NASA Astrophysics Data System (ADS)

    Hüttel, Andreas K.; Steele, Gary A.; Witkamp, Benoit; Poot, Menno; Kouwenhoven, Leo P.; van der Zant, Herre S. J.

    2009-07-01

    We have observed the transversal vibration mode of suspended carbon nanotubes at millikelvin temperatures by measuring the single-electron tunneling current. The suspended nanotubes are actuated contact-free by the radio frequency electric field of a nearby antenna; the mechanical resonance is detected in the time-averaged current through the nanotube. Sharp, gate-tuneable resonances due to the bending mode of the nanotube are observed, combining resonance frequencies of up to \

  18. Reversible separation of single-walled carbon nanotubes in bundles

    SciTech Connect

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

    2008-08-25

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

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

    Microsoft Academic Search

    J. Justin Gooding

    2005-01-01

    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

  20. Electron transport through single carbon nanotubes

    SciTech Connect

    Schenkel, Thomas; Chai, G.; Heinrich, H.; Chow, L.; Schenkel, T.

    2007-08-01

    We report on the transport of energetic electrons through single, well aligned multi-wall carbon nanotubes (CNT). Embedding of CNTs in a protective carbon fiber coating enables the application of focused ion beam based sample preparation techniques for the non-destructive isolation and alignment of individual tubes. Aligned tubes with lengths of 0.7 to 3 mu m allow transport of 300 keV electrons in a transmission electron microscope through their hollow cores at zero degree incident angles and for a misalignment of up to 1 degree.

  1. Frontiers of the Physics of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Dresselhaus, Mildred

    2013-03-01

    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.

  2. A technique to directly excite Luttinger liquid collective modes in carbon nanotubes at GHz frequencies

    Microsoft Academic Search

    P. J. Burke

    2002-01-01

    We present a technique to directly excite Luttinger liquid collective modes\\u000ain carbon nanotubes at GHz frequencies. By modeling the nanotube as a\\u000anano-transmission line with distributed kinetic and magnetic inductance as well\\u000aas distributed quantum and electrostatic capacitance, we calculate the complex,\\u000afrequency dependent impedance for a variety of measurement geometries. Exciting\\u000avoltage waves on the nano-transmission line is

  3. Plasmon dispersion of low-frequency oscillations in metallic double-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Fathalian, Ali; Nikjo, Shahram

    2009-11-01

    The dispersion properties of low-frequency electromagnetic waves in metallic double-walled carbon nanotubes (DWCNTs) are investigated. We assume that metallic DWCNTs are charged due to field emission, and hence metallic nanotubes can be regarded as charged dust rods surrounded by degenerate electrons and ions. Calculations are performed for transverse magnetic (TM) and transverse electric (TE) waves, respectively, by solving Maxwell and hydrodynamic equations with appropriate boundary conditions.

  4. Adaptive Materials from Carbon Nanotube - Polyurethane Nanocomposites

    NASA Astrophysics Data System (ADS)

    Powers, Daniel; Koerner, Hilmar

    2005-04-01

    Adaptive materials undergo large-scale shape or property change in response to an external stimulus such as stress, temperature, light, or pH. Technological uses range from durable, shape recovery eye-glass frames, to temperature sensitive switches, to the generation of stress to induced mechanical motion. Here in, we demonstrate that the uniform dispersion of 1-5vol% of carbon nanotubes in a thermoplastic elastomer yields nanocomposites that can store and subsequently release, through remote means, up to 50% more recovery stress than the pristine resin. The anisotropic nanotubes increase the rubbery modulus by a factor of 2 to 5 (for 1-5vol%) and improve shape fixity by enhancing strain-induced crystallization. Non-radiative decay of infrared photons absorbed by the nanotubes raises the internal temperature, melting the polymer crystallites (which act as physical cross-links that secure the deformed shape) and remotely triggering the release of the stored strain energy. Comparable effects occur for electrically-induced actuation associated with Joule heating of the matrix when a current is passed through the conductive percolative network of the nanotubes within the resin.

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

    NASA Astrophysics Data System (ADS)

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

    2004-05-01

    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 ? 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 shifts and splittings depend on the value of ?/?0 and are quantitatively consistent with theories based on the Aharonov-Bohm effect. These results represent evidence of the influence of the Aharonov-Bohm phase on the band gap of a solid.

  6. Oscillation of carbon molecules inside carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Thamwattana, Ngamta; Cox, Barry J.; Hill, James M.

    2009-04-01

    In this paper, we investigate the mechanics of a nanoscaled gigahertz oscillator comprising a carbon molecule oscillating within the centre of a uniform concentric ring or bundle of carbon nanotubes. Two kinds of oscillating molecules are considered, which are a carbon nanotube and a C60 fullerene. Using the Lennard-Jones potential and the continuum approach, we obtain a relation between the bundle radius and the radii of the nanotubes forming the bundle, as well as the optimum bundle size which gives rise to the maximum oscillatory frequency for both the nanotube-bundle and the C60-bundle oscillators. While previous studies in this area have been undertaken through molecular dynamics simulations, this paper emphasizes the use of applied mathematical modelling techniques, which provides considerable insight into the underlying mechanisms of the nanoscaled oscillators. The paper presents a synopsis of the major results derived in detail by the present authors (Cox et al 2007 Proc. R. Soc. A 464 691-710 and Cox et al 2007 J. Phys. A: Math. Theor. 40 13197-208).

  7. Oscillation of carbon molecules inside carbon nanotube bundles.

    PubMed

    Thamwattana, Ngamta; Cox, Barry J; Hill, James M

    2009-04-01

    In this paper, we investigate the mechanics of a nanoscaled gigahertz oscillator comprising a carbon molecule oscillating within the centre of a uniform concentric ring or bundle of carbon nanotubes. Two kinds of oscillating molecules are considered, which are a carbon nanotube and a C(60) fullerene. Using the Lennard-Jones potential and the continuum approach, we obtain a relation between the bundle radius and the radii of the nanotubes forming the bundle, as well as the optimum bundle size which gives rise to the maximum oscillatory frequency for both the nanotube-bundle and the C(60)-bundle oscillators. While previous studies in this area have been undertaken through molecular dynamics simulations, this paper emphasizes the use of applied mathematical modelling techniques, which provides considerable insight into the underlying mechanisms of the nanoscaled oscillators. The paper presents a synopsis of the major results derived in detail by the present authors (Cox et al 2007 Proc. R. Soc. A 464 691-710 and Cox et al 2007 J. Phys. A: Math. Theor. 40 13197-208). PMID:21825331

  8. Carbon Nanotube-enhanced Carbon-phenolic Ablator Material

    NASA Technical Reports Server (NTRS)

    Nikolaev, P.; Stackpoole, M.; Fan, W.; Cruden, B.; Waid, M.; Maloney, P.; Arepalli, S.; Arnold, J.; Partridge, H.; Yowell, L.

    2006-01-01

    Phenolic impregnated carbon ablator (PICA) is a thermal protection system (TPS) material developed at NASA Ames Research Center in the mid-90 s for Discovery missions. It was used on the Stardust return capsule heat shield which successfully executed the highest speed Earth entry to date on January 15, 2006. PICA is a porous fibrous carbon insulation infiltrated with phenolic resin, and is an excellent ablator that is effective for heating rates up to 1000 W/sq cm. It is one of several candidate TPS materials for the next generation of crewed spacecraft for Lunar and Mars missions. We will describe an ongoing research effort at NASA to improve mechanical properties of the phenolic matrix with carbon nanotubes. The aim is two-fold: to increase overall TPS strength during reentry and to improve Micrometeoroid/Orbital Debris (MMOD) protection in space. The former requires at least a good dispersion of nanotubes in phenolic, while the latter also requires covalent bonding between them to couple and transfer impact energy effectively from matrix to nanotubes. We will discuss the required chemical functionalization of nanotubes, processing issues and test results.

  9. Binding energy of the trion complex in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Meliksetyan, Areg; Bondarev, Igor

    2014-03-01

    We derive an analytical expression for the binding energy of the trion complex (charged exciton) in small diameter (~1nm) carbon nanotubes. We use the (asymptotically exact) Landau-Herring approach that was previously implemented by one of us (Ref.) to evaluate the biexciton binding energy in carbon nanotubes. Within this approach, we find the universal asymptotic relationship between the trion, biexciton and exciton binding energies in the same carbon nanotube. Particularly, the trion binding energy we obtained is estimated to be greater than the corresponding biexciton binding energy by a factor ~1.5 for carbon nanotubes with diameters ~1nm, which reasonably agrees with the latest non-linear optical spectroscopy measurements reported in Refs. and (1.46 for the (6,5) nanotube and 1.42 for the (9,7) nanotube, respectively). ARO-W911NF-11-1-0189 (A.M.), DOE-DE-SC0007117 (I.B.).

  10. Atomic structure determination of carbon nanotubes by electron diffraction

    NASA Astrophysics Data System (ADS)

    Liu, Zejian

    This dissertation comprises developing and applying an electron diffraction technique to determine and map the chiral indices of carbon nanotubes which dictate their chemical and physical properties. Due to the tubular geometry of carbon nanotubes, the diffraction intensity is usually elongated to form layer lines perpendicular to the tubule axis. Based on helical diffraction theory, we show that the diffraction intensity on a layer line is modulated in dominance by the Bessel functions of the lowest order and all the other Bessel functions of higher orders contribute negligibly to the diffraction intensity. By examining the peak positions of the scattering intensities on the non-equatorial principal layer lines in the electron diffraction pattern of a single-walled carbon nanotube, we can assign unambiguously the chiral indices (u,nu) of the carbon nanotube, which define its atomic structure. A systematic procedure has been established for experimental structure determination. Electron diffraction patterns of carbon nanotubes were obtained using a modern transmission electron microscope equipped with a field emission gun. To avoid damaging the atomic structure of carbon nanotubes, the electron microscope has been operated at 80 kV above which knock-on radiation damage to the carbon nanotubes occurs. Experimentally, we have determined accurately the atomic structure of more than 200 isolated individual carbon nanotubes, and a mapping of these nanotubes in terms of their diameter, helicity and metallicity has been implemented. We have also studied in detail the symmetry properties of electron diffraction from carbon nanotubes both theoretically and experimentally. We show that the electron diffraction pattern of a single-walled carbon nanotube always has 2mm symmetry. However, for the case of multiwalled carbon nanotubes, the 2mm symmetry can break down when coherent interferences of the electron waves from two different shells take place such as when the two shells of the same helicity but their chiral indices ( u,nu) have opposite evenness/oddity. The helical electron diffraction theory has also been extended to study the structure of deformed carbon nanotubes such as elliptical and twisted carbon nanotubes. Finally, we have discussed the possibility of determining the handedness of both single-walled and multiwalled carbon nanotubes by electron diffraction.

  11. Carbon Nanotubes Used in Electroanalysis

    NASA Astrophysics Data System (ADS)

    Hu, C. G.; Feng, B.

    The fabrication of the carboxyl-modified CNT electrode was described. The electroanalytical investigation of sulfadiazine has been conducted in alkaline aqueous solution at the CNT electrode by voltammetry. Highly reproducible and well-defined cyclic voltammograms were obtained for sulfadiazine with a very good signal to background (S/B) ratio. However, no fouling of the electrode was observed at the CNT electrode within the experimental period of several hours, which illustrated that the CNT electrode was much better than traditional electrodes. Meanwhile, the detection of trace sulfadiazine in milk was also conducted by cyclic voltammetry with satisfactory ratio of recovery, indicating that the nanotube electrode can be used in routine monitoring of sulfadiazine residues in food.

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

    PubMed

    Khlobystov, Andrei N

    2011-12-27

    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

  13. Metal and alloy nanowires: Iron and invar inside carbon nanotubes

    Microsoft Academic Search

    N. Grobert; M. Mayne; M. Terrones; J. Sloan; R. E. Dunin-Borkowski; R. Kamalakaran; T. Seeger; H. Terrones; M. Rühle; D. R. M. Walton; H. W. Kroto; J. L. Hutchison

    2001-01-01

    Pyrolysis of hydrocarbons over metal catalysts has proved to be a very efficient and versatile technique for generating metal-filled carbon nanotubes. At reduced pressures Fe-filled nanotubes are formed efficiently from ferrocene and C60. Recently, alloys such as invar (Fe65Ni35) were successfully introduced in carbon nanotubes by pyrolysing aerosols of nickelocene\\/ferrocene (Cp2Ni\\/Cp2Fe) mixtures dissolved in benzene. With the introduction of Invar

  14. Continuum modeling of carbon nanotube-based super-structures

    Microsoft Academic Search

    Konstantinos I. Tserpes; Paraskevas Papanikos

    2009-01-01

    The recently discovered carbon nanotube-based super-nanotubes (SNTs), super-graphene (SG) and super-square (SS) are modeled using the equivalent beam concept (EBC). By substituting carbon nanotubes with elastic beams of identical mechanical behavior, the atomic lattice is simulated with the classical strut-based lattice, thus enabling continuum modeling using finite elements. Young’s modulus, failure stress and strain of the SNTs are derived and

  15. Multifunctional brushes made from carbon nanotubes.

    PubMed

    Cao, Anyuan; Veedu, Vinod P; Li, Xuesong; Yao, Zhaoling; Ghasemi-Nejhad, Mehrdad N; Ajayan, Pulickel M

    2005-07-01

    Brushes are common tools for use in industry and our daily life, performing a variety of tasks such as cleaning, scraping, applying and electrical contacts. Typical materials for constructing brush bristles include animal hairs, synthetic polymer fibres and metal wires (see, for example, ref. 1). The performance of these bristles has been limited by the oxidation and degradation of metal wires, poor strength of natural hairs, and low thermal stability of synthetic fibres. Carbon nanotubes, having a typical one-dimensional nanostructure, have excellent mechanical properties, such as high modulus and strength, high elasticity and resilience, thermal conductivity and large surface area (50-200 m2 g(-1)). Here we construct multifunctional, conductive brushes with carbon nanotube bristles grafted on fibre handles, and demonstrate their several unique tasks such as cleaning of nanoparticles from narrow spaces, coating of the inside of holes, selective chemical adsorption, and as movable electromechanical brush contacts and switches. The nanotube bristles can also be chemically functionalized for selective removal of heavy metal ions. PMID:15951816

  16. Single carbon-nanotube photonics and optoelectronics

    NASA Astrophysics Data System (ADS)

    Kato, Yuichiro K.

    2015-03-01

    Single-walled carbon nanotubes have unique optical properties as a result of their one-dimensional structure. Not only do they exhibit strong polarization for both absorption and emission, large exciton binding energies allow for room-temperature excitonic luminescence. Furthermore, their emission is in the telecom-wavelengths and they can be directly synthesized on silicon substrates, providing new opportunities for nanoscale photonics and optoelectronics. Here we discuss the use of individual single-walled carbon nanotubes for generation, manipulation, and detection of light on a chip. Their emission properties can be controlled by coupling to silicon photonic structures such as photonic crystal microcavities and microdisk resonators. Simultaneous photoluminescence and photocurrent measurements show that excitons can dissociate spontaneously, enabling photodetection at low bias voltages despite the large binding energies. More recently, we have found that alternating gate-voltages can generate optical pulse trains from individual nanotubes. Ultimately, these results may be combined to achieve further control over photons at the nanoscale. Work supported by KAKENHI, The Canon Foundation, The Asahi Glass Foundation, and JSPS Open Partnership Joint Projects, as well as the Nanotechnology Platform and Photon Frontier Network Program of MEXT, Japan.

  17. Aligned carbon nanotubes: from controlled synthesis to electronic applications

    E-print Network

    Zhou, Chongwu

    carbon nanotubes for high-performance thin-lm transistors, integrated circuits, display electronics-to-roll printed electronics, and RF elec- tronics using various types of nanomaterials including carbon nano

  18. Raman Scattering in Carbon Nanotubes Christian Thomsen1

    E-print Network

    Nabben, Reinhard

    of single-walled carbon nanotubes reflect the electron and phonon confinement as well as the cylindrical with resonant excitation it can be used to determine the nanotube microscopic structure. Metallic. In this Chapter we first introduce the vibrational, electronic, and optical properties of carbon tubes and explain

  19. Magnetoresistive polyaniline/multi-walled carbon nanotube nanocomposites with negative

    E-print Network

    Guo, John Zhanhu

    are observed in 30 wt% Fe3O4/ PANI6 and 20 wt% BaTiO3/PANI8 nanocomposites synthesized by the surface initiatedMagnetoresistive polyaniline/multi-walled carbon nanotube nanocomposites with negative permittivity magnetoresistance (GMR) in as-received multi-walled carbon nanotubes (MWNTs), pure polyani- line (PANI) synthesized

  20. Single walled carbon nanotube network electrodes for dye solar cells

    Microsoft Academic Search

    Daniel D. Tune; Benjamin S. Flavel; Jamie S. Quinton; Amanda V. Ellis; Joseph G. Shapter

    2010-01-01

    The photovoltaic properties of a new working electrode for dye sensitised solar cells, consisting of networks of covalently bound single walled carbon nanotubes on indium tin oxide, have been investigated. Following covalent sensitisation of the carbon nanotube networks with a ruthenium dye an appreciable cathodic photocurrent is measured upon illumination with simulated sunlight. Significant increases in photocurrent density are observed

  1. WIRELESS FLEXIBLE STRAIN SENSOR BASED ON CARBON NANOTUBE PIEZORESISTIVE NETWORKS

    E-print Network

    Paris-Sud XI, Université de

    WIRELESS FLEXIBLE STRAIN SENSOR BASED ON CARBON NANOTUBE PIEZORESISTIVE NETWORKS FOR EMBEDDED MEASUREMENT OF STRAIN IN CONCRETE F. Michelis1-2 , L. Bodelot3 , C.-S. Cojocaru2 , J.-L. Sorin1 , Y proposes a new type of low-cost strain sensor, based on piezoresistive carbon nanotube (CNT) network

  2. DNA Translocating Through a Carbon Nanotube Can Increase Ionic Current

    PubMed Central

    Park, Jae Hyun; He, Jin; Gyarfas, Brett; Lindsay, Stuart; Krsti?, Predrag S.

    2012-01-01

    DNA translocation through a narrow, single-walled carbon nanotube can be accompanied by large increases of ion current, recently observed in contrast to the ion current blockade. We use molecular dynamics simulations to show large electro-osmotic flow can be turned into a large net current via ion-selective filtering by a DNA molecule inside the carbon nanotube. PMID:23090315

  3. Anode Sheath Switching in a Carbon Nanotube Arc Plasma

    SciTech Connect

    Abe Fetterman, Yevgeny Raitses, and Michael Keidar

    2008-04-08

    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.

  4. [Functionalization of carbon nanotubes for multimodal drug delivery].

    PubMed

    Mielcarek, Jadwiga; Skupin, Paulina

    2011-01-01

    Nanotechnology is a very promising technology with a potential that can revolutionise the pharmaceutical industry. One interesting nanostructure are carbon nanotubes whose application possibilities are restricted by their solubility. Their solubility can be improved by applying endo- and exohedral modifications. The paper offers a review of the hitherto applied methods of functionalisation permitting the use of carbon nanotubes for biomedical purposes. PMID:21812234

  5. Carbon nanotubes from catalytic pyrolysis of deoiled asphalt

    Microsoft Academic Search

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

    2007-01-01

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

  6. A phase-stabilized carbon nanotube fiber laser frequency comb

    E-print Network

    Washburn, Brian

    -filled kagome photonic crystal fiber reference, while the CW laser is simultaneously compared to anotherA phase-stabilized carbon nanotube fiber laser frequency comb Jinkang Lim1 , Kevin Knabe1 , Karl A by a 167 MHz repetition frequency erbium-doped fiber ring laser using a carbon nanotube saturable absorber

  7. ORIGINAL PAPER Conceptual design of carbon nanotube processes

    E-print Network

    Pike, Ralph W.

    - ability analysis showed that both process designs were economically feasible. For the CNT-PFR process online: 10 January 2007 Ó Springer-Verlag 2007 Abstract Carbon nanotubes, discovered in 1991, are a new. The conceptual designs of two processes are described for the industrial-scale production of carbon nanotubes

  8. Load transfer mechanism in carbon nanotube ropes , Wing Kam Liub

    E-print Network

    and multi-walled carbon nanotubes (MWCNT). As shown in the rest of this paper, despite the high stiffness are often governed by the inter-tube van der Waals interaction. The possibility of using SWCNT and MWCNT-- walled carbon nanotube (MWCNT) with nested, con- centric shells, the degree of load transfer between

  9. Alignment of Multiwall Carbon Nanotubes in Polymer Composites by Dielectrophoresis

    Microsoft Academic Search

    Ming-Wen Wang

    2009-01-01

    Studies have proved that enhancing polymer matrices by adding carbon nanotubes to form structural reinforcements and to increase electrical conductivity has significantly improved mechanical and electrical properties at very low carbon nanotube loading. That mechanical and electrical properties of aligned composites are better than those of random ones has been demonstrated in past studies; however, alignment is not easy to

  10. Coupled oscillations of double-walled carbon nanotubes Giacomo Poa

    E-print Network

    Ghoniem, Nasr M.

    of fullerenes inside nano- tubes were calculated by Hodak and Girifalco,13 their appli- cations in tribologyCoupled oscillations of double-walled carbon nanotubes Giacomo Poa and N. M. Ghoniema Department of the coupled axial and angular oscillations of double-walled carbon nanotubes DWNTs was performed using

  11. Mathematical Modelling for a C60 Carbon Nanotube Oscillator

    Microsoft Academic Search

    Barry J. Cox; Ngamta Thamwattana; James M. Hill

    2006-01-01

    The discovery of fullerenes C60 and carbon nanotubes has created an enormous impact on nanotechnology. Because of their unique mechanical and electronic properties, such as low weight, high strength, flexibility and thermal stability, fullerenes C60 and carbon nanotubes are of considerable interest to researchers from many scientific areas. One problem that has attracted much attention is the creation of gigahertz

  12. Structural and mechanical properties of partially unzipped carbon nanotubes

    Microsoft Academic Search

    Chun Tang; Wanlin Guo; Changfeng Chen

    2011-01-01

    We report molecular dynamics simulations of structural and mechanical properties of partially unzipped carbon nanotubes. Our results show that in the absence of edge passivation, partially unzipped carbon nanotubes are unstable with rising temperature depending on the geometry of cutting. When the length-to-width ratio of the graphene segment is not sufficiently large, the dangling bonds at the cutting front tend

  13. Microfabricated breath sensor based on carbon nanotubes for respiration monitoring

    Microsoft Academic Search

    Hai Liu; Xiaohang Chen; Dong Xu; Zhongyu Hou; Yafei Zhang

    2009-01-01

    A microfabricated breath sensor based on multi-walled carbon nanotubes (MWCNTs) has been designed, developed and tested. This sensor has a simple capacitor structure, including a pair of metal electrodes fabricated by micromachining, which are then coated by a layer of carbon nanotubes. This structure takes advantage of the unique electrical property of MWCNTs in the small gap space as a

  14. Carbon Nanotubes Growth on Graphite Fibers

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehoczky, S. L.; Muntele, I.; Ila, D.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Carbon nanotubes (CNT) were synthesized on graphite fibers by thermal Chemical Vapor Deposition (CVD). On the fiber surface, iron nanoparticles are coated and act as catalysts for CNT growth. The growth temperature ranges from 550 to 1000 C at an ambient pressure. Methane and hydrogen gases with methane contents of 10% to 100% are used for the CNT synthesis. At high growth temperatures (greater than 800 C), the rapid inter-diffusion of the transition metal iron on the graphite surface results in a rough fiber surface with no CNT grown on the surface. When the growth temperature is relatively low (650 - 800 C), CNT are fabricated on the graphite surface with catalytic particles on the nanotube top ends. Using micro Raman spectroscopy in the breath mode region, single-walled or multi-walled CNT can be determined, depending on methane concentrations.

  15. Optical properties of C(60) and carbon nanotubes

    Microsoft Academic Search

    James Matthew Holden

    1997-01-01

    Single-wall carbon nanotubes have been produced by dc arc-discharge vaporization of a graphite anode containing a central core of pure cobalt metal catalyst under inert He atmosphere. Transmission electron micrographs show bundles of ˜1.3 nm diameter carbon nanotubes along with large amounts of impurity carbon including amorphous carbon, partially graphitized nanoparticles, nanoparticles of cobalt and cobalt carbide, and fullerenes are

  16. Single-Walled Carbon Nanotubes: From Discovery to Application

    Microsoft Academic Search

    Ching-Hwa Kiang

    1998-01-01

    Single-walled carbon nanotubes, an all carbon polymer derived from fullerence research, has recently been discovered to be stable and possess useful chemical, electrical, and mechanical properties. These tubular carbon materials are composed of single-layer graphene cylinders and have dimensions on the nanometer scale. The discovery and catalytic synthesis of single-walled carbon nanotubes will be discussed. A growth model, consistent with

  17. Study of the alignment of multiwalled carbon nanotubes using dielectrophoresis

    NASA Astrophysics Data System (ADS)

    Zhang, Chen; Breedon, M.; Wlodarski, W.; Kalantar-zadeh, K.

    2007-12-01

    Presented is the dielectrophoresis of multiwalled carbon nanotubes on piezoelectric substrates patterned with gold inter digitated electrodes. An alternating current oscillating at frequencies of 1 kHz and 150 kHz at a peak-to-peak (p-p) voltage of 1V to 10V was applied to the electrodes, aligning carbon nanotubes suspended in droplets of isopropyl alcohol (IPA). The carbon nanotubes were suspended in a dielectric medium (IPA) at a concentration of approx 0.1 mg/mL and stabilized with sodium citrate (0.02 mg/ml). Sonicated for two hours and spun down in a centrifuge for 30 minutes at 4500 rpm. The carbon nanotubes used in the DEP experimentation were multiwalled carbon nanotubes with aspect ratios of approx 100:1.

  18. Toxicity and Clearance of Intratracheally Administered Multiwalled Carbon Nanotubes from Murine Lung

    Microsoft Academic Search

    Ji-Eun Kim; Hwang-Tae Lim; Arash Minai-Tehrani; Jung-Taek Kwon; Ji-Young Shin; Chang-Gyu Woo; Mansoo Choi; Jongho Baek; Dae Hong Jeong; Yoon-Cheol Ha; Chan-Hee Chae; Kyung-Suk Song; Kang-Ho Ahn; Ji-Hyun Lee; Ha-Jung Sung; Il-Je Yu; George R. Beck Jr; Myung-Haing Cho

    2010-01-01

    Carbon nanotubes (CNT) are known to have widespread industrial applications; however, several reports indicated that these compounds may be associated with adverse effects in humans. In this study, multiwalled carbon nanotubes were administered to murine lungs intratracheally to determine whether acute and chronic pulmonary toxicity occurred. In particular, pristine multiwalled carbon nanotubes (PMWCNT) and acid-treated multiwalled carbon nanotubes (TMWCNT) were

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    We give an up-to-date review of the superconducting phenomena in 4-Angstrom carbon nanotubes embedded in aligned linear pores of the AlPO4-5 (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 Hc1 ~ 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.

  20. Spin-flip mesoscopic transport through a toroidal carbon nanotube coupled to normal metal terminals

    Microsoft Academic Search

    Hong-Kang Zhao; Qing Wang

    2005-01-01

    The spin and charge currents tunnelling through coupled toroidal carbon nanotube (TCN) system is investigated in the presence of rotating magnetic field and an Aharonov–Bohm magnetic flux. The charge current and spin current coexist in the same system as eV?0. The charge conductance, charge current, and spin current are sensitively determined by the applied magnetic fields and the quantum nature

  1. Charge transport in melt-dispersed carbon nanotubes.

    PubMed

    Hobbie, E K; Obrzut, J; Kharchenko, S B; Grulke, E A

    2006-07-28

    We investigate the effect of interfacial stabilizer on charge transport in polymer-dispersed carbon nanotubes. Despite mechanical contact, samples with dispersant show poor conductivity, which we attribute to a robust interfacial layer between contacted nanotubes. In comparison, results obtained when nanotubes are mechanically mixed into polymer melts without dispersant show much better conductivity. The difference is striking; at comparable loading, neat melt composites have resistivities five orders of magnitude smaller than those containing interfacial stabilizer. Our results highlight a fundamental issue for the engineering of conducting carbon nanotube composites; dispersion stability will typically be achieved at the expense of conductivity. PMID:16942179

  2. Low-Temperature Plasma Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Khare, Bishun; Meyyappan, M.

    2004-01-01

    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.

  3. Carbon nanotube oscillator surface profiling device and method of use

    DOEpatents

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

    2011-11-15

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

  4. Polyglycerol-derived amphiphiles for single walled carbon nanotube suspension

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

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

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

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Kwak, Dolhan (Technical Monitor)

    2000-01-01

    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.

  6. Electronic properties of disordered zigzag carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Rezania, Hamed

    2015-11-01

    We study the density of states of zigzag carbon nanotube (CNT) doped with both Boron and nitrogen atoms as donor and acceptor impurities, respectively. The effect of scattering of the electrons on the electronic spectrum of the system can be obtained via adding random on-site energy term to the tight binding model Hamiltonian which describes the clean system. Green's function approach has been implemented to find the behavior of electronic density. Due to Boron (Nitrogen) doping, Fermi surface tends to the valence (conduction) band of semiconductor CNT so that the energy gap width reduces. Furthermore the density of states of disordered metallic zigzag CNTs includes a peak near the Fermi energy.

  7. Adhesive Behavior of Single Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Maeno, Yohei; Ishikawa, Atsunori; Nakayama, Yoshikazu

    2010-06-01

    We examined the adhesion of a carbon nanotube (CNT) tip using a manipulation technique with a transmission electron microscope. In addition, we estimated the maximum normal adhesion possibility of a CNT-based gecko tape. The adhesive behavior of a single isolated CNT to Au solid surfaces has high normal strength (6.84 nN), which has a linear relation to the cross section of a CNT, indicating the mechanism: van der Waals force was inferred from the contact of two flat surfaces. Adhesion measurements conducted on several surface materials verify that the surface chemistry affects adhesive properties of CNT tips.

  8. Carbon Nanotubes Reinforced Composites for Biomedical Applications

    PubMed Central

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

    2014-01-01

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

  9. Cell mobility after endocytosis of carbon nanotubes

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    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.

  10. Micropreconcentration units based on carbon nanotubes (CNT)

    Microsoft Academic Search

    Chaudhery Mustansar Hussain; Somenath Mitra

    2011-01-01

    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

  11. Carbon Nanotubes: Present and Future Commercial Applications

    NASA Astrophysics Data System (ADS)

    De Volder, Michael F. L.; Tawfick, Sameh H.; Baughman, Ray H.; Hart, A. John

    2013-02-01

    Worldwide commercial interest in carbon nanotubes (CNTs) is reflected in a production capacity that presently exceeds several thousand tons per year. Currently, bulk CNT powders are incorporated in diverse commercial products ranging from rechargeable batteries, automotive parts, and sporting goods to boat hulls and water filters. Advances in CNT synthesis, purification, and chemical modification are enabling integration of CNTs in thin-film electronics and large-area coatings. Although not yet providing compelling mechanical strength or electrical or thermal conductivities for many applications, CNT yarns and sheets already have promising performance for applications including supercapacitors, actuators, and lightweight electromagnetic shields.

  12. Microwave devices: carbon nanotubes as cold cathodes.

    PubMed

    Teo, Kenneth B K; Minoux, Eric; Hudanski, Ludovic; Peauger, Franck; Schnell, Jean-Philippe; Gangloff, Laurent; Legagneux, Pierre; Dieumegard, Dominique; Amaratunga, Gehan A J; Milne, William I

    2005-10-13

    To communicate, spacecraft and satellites rely on microwave devices, which at present are based on relatively inefficient thermionic electron sources that require heating and cannot be switched on instantaneously. Here we describe a microwave diode that uses a cold-cathode electron source consisting of carbon nanotubes and that operates at high frequency and at high current densities. Because it weighs little, responds instantaneously and has no need of heating, this miniaturized electron source should prove valuable for microwave devices used in telecommunications. PMID:16222290

  13. Mechanical properties of polygonal carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Huang, Ling; Cao, Dapeng

    2012-08-01

    A group of polygonal carbon nanotubes (P-CNTs) have been designed and their mechanical behavior was investigated by classical molecular dynamics simulations. The research aimed at exploring the effects of structure, temperature, and strain rate on the mechanical properties. The results indicate that the Young's modulus of P-CNTs is lower than those of circumcircle carbon nanotubes (C-CNT). Moreover, with an increase in the number of sides to the polygons, the Young's modulus increases and is much closer to that of C-CNT. The effects of temperature and strain rate on the mechanical properties of P-CNTs show that the higher temperature and slower strain rate result in a lower critical strain and weaker tensile strength. In addition, it was found that the critical strains of P-CNTs are dependent on the tube size. Finally, we used the transition-state theory model to predict the critical strain of P-CNTs at given experimental conditions. It is expected that this work could provide feasible means to manipulate the mechanical properties of novel P-CNTs and facilitate the mechanical application of nanostructures as potential electronic devices.A group of polygonal carbon nanotubes (P-CNTs) have been designed and their mechanical behavior was investigated by classical molecular dynamics simulations. The research aimed at exploring the effects of structure, temperature, and strain rate on the mechanical properties. The results indicate that the Young's modulus of P-CNTs is lower than those of circumcircle carbon nanotubes (C-CNT). Moreover, with an increase in the number of sides to the polygons, the Young's modulus increases and is much closer to that of C-CNT. The effects of temperature and strain rate on the mechanical properties of P-CNTs show that the higher temperature and slower strain rate result in a lower critical strain and weaker tensile strength. In addition, it was found that the critical strains of P-CNTs are dependent on the tube size. Finally, we used the transition-state theory model to predict the critical strain of P-CNTs at given experimental conditions. It is expected that this work could provide feasible means to manipulate the mechanical properties of novel P-CNTs and facilitate the mechanical application of nanostructures as potential electronic devices. Electronic supplementary information (ESI) available: Table for comparison of number of atoms per unit cell and transverse size; transition-state theory fitting for 3-, 5-, 6-, and 8-CNT. See DOI: 10.1039/c2nr31264f

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

    PubMed Central

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

    2012-01-01

    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

  15. Carbon Nanotubes in Regenerative Medicine

    Microsoft Academic Search

    Bhavna S. Paratala; Balaji Sitharaman

    \\u000a This chapter focuses on the latest developments in applications of carbonnanotubes (CNTs) for regenerative medicine. Regenerative\\u000a Medicine focuses on technologies to create functional tissues to repair or replace tissues or organs lost due to trauma or\\u000a disease. Carbon nonotubes (CNTs) have been under investigation in the past decade for an array of applications due to their\\u000a unique and versatile properties.

  16. Covalent Crosslinking of Carbon Nanotube Materials for Improved Tensile Strength

    NASA Technical Reports Server (NTRS)

    Baker, James S.; Miller, Sandi G.; Williams, Tiffany A.; Meador, Michael A.

    2013-01-01

    Carbon nanotubes have attracted much interest in recent years due to their exceptional mechanical properties. Currently, the tensile properties of bulk carbon nanotube-based materials (yarns, sheets, etc.) fall far short of those of the individual nanotube elements. The premature failure in these materials under tensile load has been attributed to inter-tube sliding, which requires far less force than that needed to fracture individual nanotubes.1,2 In order for nanotube materials to achieve their full potential, methods are needed to restrict this tube-tube shear and increase inter-tube forces.Our group is examining covalent crosslinking between the nanotubes as a means to increase the tensile properties of carbon nanotube materials. We are working with multi-walled carbon nanotube (MWCNT) sheet and yarn materials obtained from commercial sources. Several routes to functionalize the nanotubes have been examined including nitrene, aryl diazonium, and epoxide chemistries. The functional nanotubes were crosslinked through small molecule or polymeric bridges. Additionally, electron beam irradiation induced crosslinking of the non-functional and functional nanotube materials was conducted. For example, a nanotube sheet material containing approximately 3.5 mol amine functional groups exhibited a tensile strength of 75 MPa and a tensile modulus of 1.16 GPa, compared to 49 MPa and 0.57 GPa, respectively, for the as-received material. Electron beam irradiation (2.2x 1017 ecm2) of the same amine-functional sheet material further increased the tensile strength to 120 MPa and the modulus to 2.61 GPa. This represents approximately a 150 increase in tensile strength and a 360 increase in tensile modulus over the as-received material with only a 25 increase in material mass. Once we have optimized the nanotube crosslinking methods, the performance of these materials in polymer matrix composites will be evaluated.

  17. Adsorption of selected volatile organic vapors on multiwall carbon nanotubes.

    PubMed

    Shih, Yang-hsin; Li, Mei-syue

    2008-06-15

    Carbon nanotubes are expected to play an important role in sensing, pollution treatment and separation techniques. This study examines the adsorption behaviors of volatile organic compounds (VOCs), n-hexane, benzene, trichloroethylene and acetone on two multiwall carbon nanotubes (MWCNTs), CNT1 and CNT2. Among these VOCs, acetone exhibits the highest adsorption capacity. The highest adsorption enthalpies and desorption energies of acetone were also observed. The strong chemical interactions between acetone and both MWCNTs may be the result from chemisorption on the topological defects. The adsorption heats of trichloroethylene, benzene, and n-hexane are indicative of physisorption on the surfaces of both MWCNTs. CNT2 presents a higher adsorption capacity than CNT1 due to the existence of an exterior amorphous carbon layer on CNT2. The amorphous carbon enhances the adsorption capacity of organic chemicals on carbon nanotubes. The morphological and structure order of carbon nanotubes are the primary affects on the adsorption process of organic chemicals. PMID:17980962

  18. Superconducting characteristics of 4-? carbon nanotube–zeolite composite

    PubMed Central

    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

    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

  19. Multiscale carbon nanotube-carbon fiber reinforcement for advanced epoxy composites.

    PubMed

    Bekyarova, E; Thostenson, E T; Yu, A; Kim, H; Gao, J; Tang, J; Hahn, H T; Chou, T-W; Itkis, M E; Haddon, R C

    2007-03-27

    We report an approach to the development of advanced structural composites based on engineered multiscale carbon nanotube-carbon fiber reinforcement. Electrophoresis was utilized for the selective deposition of multi- and single-walled carbon nanotubes (CNTs) on woven carbon fabric. The CNT-coated carbon fabric panels were subsequently infiltrated with epoxy resin using vacuum-assisted resin transfer molding (VARTM) to fabricate multiscale hybrid composites in which the nanotubes were completely integrated into the fiber bundles and reinforced the matrix-rich regions. The carbon nanotube/carbon fabric/epoxy composites showed approximately 30% enhancement of the interlaminar shear strength as compared to that of carbon fiber/epoxy composites without carbon nanotubes and demonstrate significantly improved out-of-plane electrical conductivity. PMID:17326671

  20. Carbon nanotubes enhanced the lead toxicity on the freshwater fish

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  1. SU(4) Kondo Effect in Carbon Nanotube Quantum Dots: Kondo Effect without Charge Quantization

    E-print Network

    Finkelstein, Gleb

    SU(4) Kondo Effect in Carbon Nanotube Quantum Dots: Kondo Effect without Charge Quantization Gleb: NSF DMR-0239748 #12;Electronic band structure, sample Coulomb blockade Kondo effect / Mixed Valence -apparent Kondo behavior without charge quantization -Kondo in magnetic field #12;Samples doped Si SiO2

  2. High-Frequency Effects in Carbon Nanotube Interconnects and Implications for On-Chip Inductor Design

    E-print Network

    -walled carbon nanotube (MWCNT) bundle interconnects. Our analysis reveals for the first time that skin effect method for extracting the inductance of both SWCNT and MWCNT bundles (as shown in Fig. 2) has been) concept, magnetic self- and mutual- inductance of SWCNT and MWCNT can be derived based on the procedure

  3. Dynamic light scattering from acoustic modes in single-walled carbon nanotubes

    Microsoft Academic Search

    C. E. Bottani; A. Li Bassi; M. G. Beghi; A. Podestà; P. Milani; A. Zakhidov; R. Baughman; D. A. Walters; R. E. Smalley

    2003-01-01

    We report here the computation and measurement of inelastic light scattering from acoustic vibrational modes in single-walled carbon nanotubes (SWNT's). The measurement was made possible by the preparation of a sample of oriented SWNT's, partially aligned by means of a magnetic field. Long-wavelength confined longitudinal acoustic modes are described by a shell model. Their interaction with light is described by

  4. Dynamic light scattering from acoustic modes in single-walled carbon nanotubes

    Microsoft Academic Search

    C. E. Bottani; A. Li Bassi; M. G. Beghi; A. Zakhidov; R. Baughman; D. A. Walters; R. E. Smalley

    2003-01-01

    We report here the computation and measurement of inelastic light scattering from acoustic vibrational modes in single-walled carbon nanotubes ~SWNT's!. The measurement was made possible by the preparation of a sample of oriented SWNT's, partially aligned by means of a magnetic field. Long-wavelength confined longitudinal acoustic modes are described by a shell model. Their interaction with light is described by

  5. Transfer printing of the functionalized carbon nanotubes aligned by DEP

    Microsoft Academic Search

    Jung-Tang Huang; Fang-Hsun Yeh; Po-Chin Lin; Chih-Cheng Lu

    2009-01-01

    Dielectrophoresis force (DEP) has been the most common way to manipulate Carbon nanotubes either multi walled carbon nanotbues(MWCNTs) or single walled carbon nanotubes(SWNTs) for the fabrication of nanoscale electronic devices, recently. Nevertheless, with limitation of substrate areas or the restriction of operation voltage of substrate, for example the chip with circuits based on CMOS-NEMS, dielectrophoresis force is not the best

  6. Quantum electron transport in toroidal carbon nanotubes with metallic leads

    Microsoft Academic Search

    Mark Jack; Mario Encinosa

    2007-01-01

    Carbon nanotubes and carbon nanotori possess all the interesting new electronic features seen in graphene e.g. massless Dirac fermion characteristics, small spin-orbit coupling effects, and quantized conductance, along with interesting curvature and boundary condition effects closing the tube to form a torus. The authors calculate electronic transport properties such as density-of-states and transmissivity for toroidal carbon nanotubes with attached metallic

  7. Photoexcitation dynamics of coupled semiconducting carbon nanotube thin films.

    PubMed

    Mehlenbacher, Randy D; Wu, Meng-Yin; Grechko, Maksim; Laaser, Jennifer E; Arnold, Michael S; Zanni, Martin T

    2013-04-10

    Carbon nanotubes are a promising means of capturing photons for use in solar cell devices. We time-resolved the photoexcitation dynamics of coupled, bandgap-selected, semiconducting carbon nanotubes in thin films tailored for photovoltaics. Using transient absorption spectroscopy and anisotropy measurements, we found that the photoexcitation evolves by two mechanisms with a fast and long-range component followed by a slow and short-range component. Within 300 fs of optical excitation, 20% of nanotubes transfer their photoexcitation over 5-10 nm into nearby nanotube fibers. After 3 ps, 70% of the photoexcitation resides on the smallest bandgap nanotubes. After this ultrafast process, the photoexcitation continues to transfer on a ~10 ps time scale but to predominantly aligned tubes. Ultimately the photoexcitation hops twice on average between fibers. These results are important for understanding the flow of energy and charge in coupled nanotube materials and light-harvesting devices. PMID:23464618

  8. Thermo-electromagnetic sound transducer based on carbon nanotube sheet

    NASA Astrophysics Data System (ADS)

    Kozlov, Mikhail; Oh, Jiyoung

    2014-09-01

    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.

  9. Effect of nanotube functionalization on the properties of single-walled carbon nanotube\\/polyurethane composites

    Microsoft Academic Search

    Fabian Buffa; Gustavo A. Abraham; Brian P. Grady; Daniel Resasco

    2007-01-01

    A commercially available aliphatic thermoplastic polyurethane formulated with a methylene bis(cyclohexyl) diisocyanate hard segment and a poly(tetramethylene oxide) soft segment and chain-extended with 1,4-butanediol was dissolved in dimethyl- formamide and mixed with dispersed single-walled carbon nanotubes. The properties of composites made with unfunctionalized nanotubes were compared with the proper- ties of composites made with nanotubes functionalized to contain hydroxyl groups.

  10. Chiral graphene nanoribbon inside a carbon nanotube: ab initio study.

    PubMed

    Lebedeva, Irina V; Popov, Andrey M; Knizhnik, Andrey A; Khlobystov, Andrei N; Potapkin, Boris V

    2012-08-01

    The dispersion-corrected density functional theory (DFT-D) is applied for investigation of structure and electronic properties of a sulfur-terminated graphene nanoribbon (S-GNR) encapsulated in a carbon nanotube. Two mechanisms of accommodation of the GNR in the carbon nanotube, distortion of the nanotube cross-section into an elliptic shape accompanied by bending of the GNR and transformation of the GNR to a helical conformation, are analyzed. Three types of elastic distortions of the nanotube and encapsulated GNR are revealed depending on the ratio of the diameter of the nanotube cavity to the GNR width. Helical states of the GNR are shown to be stabilized by the van der Waals attraction of sulfur atoms at neighbouring edges of adjacent turns of the GNR. The results of calculations are correlated with the experimental observations for the S-GNR synthesized recently inside the carbon nanotube. The hybrid DFT calculations of band structures of zigzag GNRs terminated with different atoms demonstrate that as opposed to O- and H-GNRs, the S-GNR is metallic even when deformed inside carbon nanotubes. Possible applications of GNRs encapsulated in carbon nanotubes are discussed. PMID:22696165

  11. Chiral graphene nanoribbon inside a carbon nanotube: ab initio study

    NASA Astrophysics Data System (ADS)

    Lebedeva, Irina V.; Popov, Andrey M.; Knizhnik, Andrey A.; Khlobystov, Andrei N.; Potapkin, Boris V.

    2012-07-01

    The dispersion-corrected density functional theory (DFT-D) is applied for investigation of structure and electronic properties of a sulfur-terminated graphene nanoribbon (S-GNR) encapsulated in a carbon nanotube. Two mechanisms of accommodation of the GNR in the carbon nanotube, distortion of the nanotube cross-section into an elliptic shape accompanied by bending of the GNR and transformation of the GNR to a helical conformation, are analyzed. Three types of elastic distortions of the nanotube and encapsulated GNR are revealed depending on the ratio of the diameter of the nanotube cavity to the GNR width. Helical states of the GNR are shown to be stabilized by the van der Waals attraction of sulfur atoms at neighbouring edges of adjacent turns of the GNR. The results of calculations are correlated with the experimental observations for the S-GNR synthesized recently inside the carbon nanotube. The hybrid DFT calculations of band structures of zigzag GNRs terminated with different atoms demonstrate that as opposed to O- and H-GNRs, the S-GNR is metallic even when deformed inside carbon nanotubes. Possible applications of GNRs encapsulated in carbon nanotubes are discussed.

  12. Waveguide-integrated electroluminescent carbon nanotubes

    E-print Network

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

    2013-01-01

    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...

  13. Carbon Nanotube Devices Engineered by Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Prisbrey, Landon

    This dissertation explores the engineering of carbon nanotube electronic devices using atomic force microscopy (AFM) based techniques. A possible application for such devices is an electronic interface with individual biological molecules. This single molecule biosensing application is explored both experimentally and with computational modeling. Scanning probe microscopy techniques, such as AFM, are ideal to study nanoscale electronics. These techniques employ a probe which is raster scanned above a sample while measuring probe-surface interactions as a function of position. In addition to topographical and electrostatic/magnetic surface characterization, the probe may also be used as a tool to manipulate and engineer at the nanoscale. Nanoelectronic devices built from carbon nanotubes exhibit many exciting properties including one-dimensional electron transport. A natural consequence of onedimensional transport is that a single perturbation along the conduction channel can have extremely large effects on the device's transport characteristics. This property may be exploited to produce electronic sensors with single-molecule resolution. Here we use AFM-based engineering to fabricate atomic-sized transistors from carbon nanotube network devices. This is done through the incorporation of point defects into the carbon nanotube sidewall using voltage pulses from an AFM probe. We find that the incorporation of an oxidative defect leads to a variety of possible electrical signatures including sudden switching events, resonant scattering, and breaking of the symmetry between electron and hole transport. We discuss the relationship between these different electronic signatures and the chemical structure/charge state of the defect. Tunneling through a defect-induced Coulomb barrier is modeled with numerical Verlet integration of Schrodinger's equation and compared with experimental results. Atomic-sized transistors are ideal for single-molecule applications due to their sensitivity to electric fields with very small detection volumes. In this work we demonstrate these devices as single-molecule sensors to detect individual N-(3-Dimethylaminopropyl)- N'-ethylcarbodiimide (EDC) molecules in an aqueous environment. An exciting application of these sensors is to study individual macromolecules participating in biological reactions, or undergoing conformational change. However, it is unknown whether the associated electrostatic signals exceed detection limits. We report calculations which reveal that enzymatic processes, such as substrate binding and internal protein dynamics, are detectable at the single-molecule level using existing atomic-sized transistors. Finally, we demonstrate the use of AFM-based engineering to control the function of nanoelectronic devices without creating a point defect in the sidewall of the nanotube. With a biased AFM probe we write charge patterns on a silicon dioxide surface in close proximity to a carbon nanotube device. The written charge induces image charges in the nearby electronics, and can modulate the Fermi level in a nanotube by +/-1 eV. We use this technique to induce a spatially controlled doping charge pattern in the conduction channel, and thereby reconfigure a field-effect transistor into a pn junction. Other simple charge patterns could be used to create other devices. The doping charge persists for days and can be erased and rewritten, offering a new tool for prototyping nanodevices and optimizing electrostatic doping profiles.

  14. Design and Characterization of Carbon Nanotube Nanocomposites

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

  15. Protein stability at a carbon nanotube interface.

    PubMed

    Vaitheeswaran, S; Garcia, A E

    2011-03-28

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

  16. Protein stability at a carbon nanotube interface

    PubMed Central

    Vaitheeswaran, S.; Garcia, A. E.

    2011-01-01

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

  17. Trion electroluminescence from semiconducting carbon nanotubes.

    PubMed

    Jakubka, Florian; Grimm, Stefan B; Zakharko, Yuriy; Gannott, Florentina; Zaumseil, Jana

    2014-08-26

    Near-infrared emission from semiconducting single-walled carbon nanotubes (SWNTs) usually results from radiative relaxation of excitons. By binding an additional electron or hole through chemical or electrochemical doping, charged three-body excitons, so-called trions, are created that emit light at lower energies. The energy difference is large enough to observe weak trion photoluminescence from doped SWNTs even at room temperature. Here, we demonstrate strong trion electroluminescence from electrolyte-gated, light-emitting SWNT transistors with three different polymer-sorted carbon nanotube species, namely, (6,5), (7,5) and (10,5). The red-shifted trion emission is equal to or even stronger than the exciton emission, which is attributed to the high charge carrier density in the transistor channel. The possibility of trions as a radiative relaxation pathway for triplets and dark excitons that are formed in large numbers by electron-hole recombination is discussed. The ratio of trion to exciton emission can be tuned by the applied voltages, enabling voltage-controlled near-infrared light sources with narrow line widths that are solution-processable and operate at low voltages (<3 V). PMID:25029479

  18. Damping Augmentation of Nanocomposites Using Carbon Nanotube\\/Epoxy

    Microsoft Academic Search

    Naser Kordani; Abdolhosein Fereidoon; Mohammadreza Ashoori

    \\u000a In a nanotube-based polymeric composite structure, it is anticipated that high damping can be achieved by taking advantage\\u000a of the interfacial friction between the nanotubes and the polymer. The purpose of this paper is to investigate the structural\\u000a damping characteristics of polymeric composites containing carbon nanotubes with various kinds and amounts. The damping characteristics\\u000a of the specimens with 0, 0.5

  19. Sensitivity of Carbon Nanotube Transistors to a Charged Dielectric Coating

    Microsoft Academic Search

    Gary Pennington; Matthew H. Ervin; Alma E. Wickenden

    2008-01-01

    This paper investigates the electronic properties of single-walled carbon nanotube field-effect transistors (SWCNT-FETs) in which the SWCNT element is coated with a charged dielectric. The presence of remote charge on the surface of the dielectric is considered to effect carrier transport in the nanotube as a result of both carrier-scattering and gate screening. Nanotube device characteristics are simulated using the

  20. Carbon nanotubes as tips in non-contact SFM

    Microsoft Academic Search

    V. Barwich; M. Bammerlin; A. Baratoff; R. Bennewitz; M. Guggisberg; C. Loppacher; O. Pfeiffer; E. Meyer; H.-J. Guntherodt; J.-P. Salvetat; J.-M. Bonard; L. Forro

    2000-01-01

    The demand for sharp and stable tips suggests the use of carbon nanotubes as probing tips in scanning force microscopy. Here, we report a comparison of the long-range forces of conventional tips and nanotube tips, topographical images of various surfaces, such as Cu(111), Si(111)7×7 and NaCl(100), as well as images of a bundle of multiwalled nanotubes, which was deposited by

  1. Rheological behavior of multiwalled carbon nanotube\\/polycarbonate composites

    Microsoft Academic Search

    Petra Pötschke; Timothy D. Fornes; Donald R. Paul

    2002-01-01

    The rheological behavior of compression molded mixtures of polycarbonate containing between 0.5 and 15wt% carbon nanotubes was investigated using oscillatory rheometry at 260°C. The nanotubes have diameters between 10 and 15nm and lengths ranging from 1 to 10?m. The composites were obtained by diluting a masterbatch containing 15wt% nanotubes using a twin-screw extruder. The increase in viscosity associated with the

  2. Self-Assembly Experiments with PNA-Derivatized Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

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

    2004-09-01

    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.

  3. The growth of bunched and multi-circularly wrapped carbon nanotubes on bulk magnetic alloys by microwave enhanced hot-filament CVD with a dilute gas of ammonia

    NASA Astrophysics Data System (ADS)

    Miao, H. Y.; Lue, J. T.; Chen, S. K.; Tsau, C. H.; Ouyang, M. S.

    2005-02-01

    Bunched and multi-circularly wrapped carbon nanotubes (CNT) are observed to grow on alloy substrates based on iron group metals and copper by a microwave enhanced hot-filament method with a dilute gas of ammonia at a proper RF self-bias. The grown size of CNTs embodied in the grain sizes of conducting bulk alloy catalysts such as Cu-Ni, Cu-Fe, Cu-Co, and Cu-Ni-Fe-Co are controlled by a precursor time of hydrogen plasma etching. Species with different structural features and homogenization of CNTs samples are produced crucially attributed to various reactant gases and self-bias induced by the radio frequency field.

  4. Carbon Nanotube Microarrays Grown on Nanoflake Substrates

    NASA Technical Reports Server (NTRS)

    Schmidt, Howard K.; Hauge, Robert H.; Pint, Cary; Pheasant, Sean

    2013-01-01

    This innovation consists of a new composition of matter where single-walled carbon nanotubes (SWNTs) are grown in aligned arrays from nanostructured flakes that are coated in Fe catalyst. This method of growth of aligned SWNTs, which can yield well over 400 percent SWNT mass per unit substrate mass, exceeds current yields for entangled SWNT growth. In addition, processing can be performed with minimal wet etching treatments, leaving aligned SWNTs with superior properties over those that exist in entangled mats. The alignment of the nanotubes is similar to that achieved in vertically aligned nanotubes, which are called "carpets. " Because these flakes are grown in a state where they are airborne in a reactor, these flakes, after growing SWNTs, are termed "flying carpets. " These flakes are created in a roll-to-roll evaporator system, where three subsequent evaporations are performed on a 100-ft (approx. =30-m) roll of Mylar. The first layer is composed of a water-soluble "release layer, " which can be a material such as NaCl. After depositing NaCl, the second layer involves 40 nm of supporting layer material . either Al2O3 or MgO. The thickness of the layer can be tuned to synthesize flakes that are larger or smaller than those obtained with a 40-nm deposition. Finally, the third layer consists of a thin Fe catalyst layer with a thickness of 0.5 nm. The thickness of this layer ultimately determines the diameter of SWNT growth, and a layer that is too thick will result in the growth of multiwalled carbon nanotubes instead of single-wall nanotubes. However, between a thickness of 0.5 nm to 1 nm, single-walled carbon nanotubes are known to be the primary constituent. After this three-layer deposition process, the Mylar is rolled through a bath of water, which allows catalyst-coated flakes to detach from the Mylar. The flakes are then collected and dried. The method described here for making such flakes is analogous to that which is used to make birefringent ink that is coated on U.S. currency. After deposition, the growth is carried out in a hot-filament chemical vapor deposition apparatus. A tungsten hot filament placed in the flow of H2 at a temperature greater than 1,600 C creates atomic hydrogen, which serves to reduce the Fe catalyst into a metallic state. The catalyst can now precipitate SWNTs in the presence of growth gases. The gases used for the experiments reported are C2H2, H2O, and H2, at rates of 2, 2, and 400 standard cubic centimeters per minute (sccm), respectively. In order to retain the flakes, a cage is constructed by spot welding stainless steel or copper mesh to form an enclosed area, in which the flakes are placed prior to growth. This allows growth gases and atomic hydrogen to reach the flakes, but does not allow the flakes, which rapidly nucleate SWNTs, to escape from the cage.

  5. Elastic exciton-exciton scattering in photoexcited carbon nanotubes.

    PubMed

    Nguyen, D T; Voisin, C; Roussignol, Ph; Roquelet, C; Lauret, J S; Cassabois, G

    2011-09-16

    We report on original nonlinear spectral hole-burning experiments in single wall carbon nanotubes that bring evidence of pure dephasing induced by exciton-exciton scattering. We show that the collision-induced broadening in carbon nanotubes is controlled by exciton-exciton scattering as for Wannier excitons in inorganic semiconductors, while the population relaxation is driven by exciton-exciton annihilation as for Frenkel excitons in organic materials. We demonstrate that this singular behavior originates from the intrinsic one-dimensionality of excitons in carbon nanotubes, which display unique hybrid features of organic and inorganic systems. PMID:22026798

  6. Applications of Carbon Nanotubes in Biotechnology and Biomedicine.

    PubMed

    Bekyarova, Elena; Ni, Yingchun; Malarkey, Erik B; Montana, Vedrana; McWilliams, Jared L; Haddon, Robert C; Parpura, Vladimir

    2005-03-01

    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

  7. Applications of Carbon Nanotubes in Biotechnology and Biomedicine

    PubMed Central

    Bekyarova, Elena; Ni, Yingchun; Malarkey, Erik B.; Montana, Vedrana; McWilliams, Jared L.; Haddon, Robert C.; Parpura, Vladimir

    2009-01-01

    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

  8. Tensile Yielding of Multi-Wall Carbon Nanotube

    NASA Technical Reports Server (NTRS)

    Wei, Chenyu; Cho, Kyeongjae; Srivastava, Deepak; Parks, John W. (Technical Monitor)

    2002-01-01

    The tensile yielding of multiwall carbon nanotubes (MWCNTs) has been studied using Molecular Dynamics simulations and a Transition State Theory based model. We find a strong dependence of the yielding on the strain rate. A critical strain rate has been predicted above/below which yielding strain of a MWCNT is larger/smaller than that of the corresponding single-wall carbon nanotubes. At experimentally feasible strain rate of 1% /hour and T = 300K, the yield strain of a MWCNT is estimated to be about 3-4 % higher than that of an equivalent SWCNT (Single Wall Carbon Nanotube), in good agreement with recent experimental observations.

  9. Optimizing the thermoelectric performance of zigzag and chiral carbon nanotubes

    PubMed Central

    2012-01-01

    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

  10. Field Emission from Hybrid Diamond-like Carbon and Carbon Nanotube Composite Structures

    E-print Network

    Bristol, University of

    Information ABSTRACT: A thin diamond-like carbon (DLC) film was deposited onto a densely packed "forest" of vertically aligned multiwalled carbon nanotubes (VACNT). DLC deposition caused the tips of the CNTs to clump, porous DLC, low threshold voltage, aligned nanotubes, DLC 1. INTRODUCTION Carbon-based materials

  11. Effect of addition of carbon nanofibers and carbon nanotubes on properties of thermoplastic biopolymers

    Microsoft Academic Search

    M. D. Sanchez-Garcia; J. M. Lagaron; S. V. Hoa

    2010-01-01

    This paper presents the properties of nano-bio-composites of solvent cast polyhydroxybutyrate-co-valerate (PHBV) and polycaprolactone (PCL) containing carbon nanofiber or carbon nanotubes as a function of filler content. It is found that carbon nanotubes and nanofibers can be used to enhance the conductivity, thermal, mechanical and to enhance gas barrier properties of thermoplastic biopolyesters.

  12. Carbon Nanotube Materials for Substrate Enhanced Control of Catalytic Activity

    SciTech Connect

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

    2007-05-01

    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.

  13. Synthesis of carbon nanotubes with and without catalyst particles

    PubMed Central

    2011-01-01

    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

  14. Rotational actuator of motor based on carbon nanotubes

    DOEpatents

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

    2008-11-18

    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.

  15. Coupling of Raman Radial Breathing Modes in Double-Wall Carbon Nanotubes and Bundles of Nanotubes

    E-print Network

    Goddard III, William A.

    Coupling of Raman Radial Breathing Modes in Double-Wall Carbon Nanotubes and Bundles of NanotubesVed: February 19, 2009 Measurements of the radial breathing modes from Raman Spectroscopy have been most useful relationship between frequency and diameter. Similar correlations have also been used to predict sizes

  16. Broken SU(4) symmetry in a Kondo-correlated carbon nanotube

    NASA Astrophysics Data System (ADS)

    Schmid, Daniel R.; Smirnov, Sergey; Marga?ska, Magdalena; Dirnaichner, Alois; Stiller, Peter L.; Grifoni, Milena; Hüttel, Andreas K.; Strunk, Christoph

    2015-04-01

    Understanding the interplay between many-body phenomena and nonequilibrium in systems with entangled spin and orbital degrees of freedom is a central objective in nanoelectronics. We demonstrate that the combination of Coulomb interaction, spin-orbit coupling, and valley mixing results in a particular selection of the inelastic virtual processes contributing to the Kondo resonance in carbon nanotubes at low temperatures. This effect is dictated by conjugation properties of the underlying carbon nanotube spectrum at zero and finite magnetic field. Our measurements on a clean carbon nanotube are complemented by calculations based on a field-theoretical Keldysh approach to the nonequilibrium Kondo problem which well reproduces the rich experimental observations in Kondo transport.

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

    NASA Astrophysics Data System (ADS)

    Dappe, Y. J.

    2014-02-01

    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.

  18. Modeling Ballistic Current Flow in Carbon Nanotube Wires

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  19. 204 IEEE TRANSACTIONS ON NANOBIOSCIENCE, VOL. 5, NO. 3, SEPTEMBER 2006 Using Carbon Nanotubes to Absorb

    E-print Network

    Zhang, WJ "Chris"

    fact that hydrogen sulfide can be adsorbed by activated carbon. The carbon nanotube is an excellent activated carbon in this regard. Fluorescence intensity of the carbon nanotube with and without immersion204 IEEE TRANSACTIONS ON NANOBIOSCIENCE, VOL. 5, NO. 3, SEPTEMBER 2006 Using Carbon Nanotubes

  20. Synthesis and characterization of next-generation multifunctional material architectures : aligned carbon nanotube carbon matrix nanocomposites

    E-print Network

    Stein, Itai Y

    2013-01-01

    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 ...