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Sample records for carbon nanotube magnet

  1. 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.

  2. Carbon nanotube superlattices in a magnetic field

    NASA Astrophysics Data System (ADS)

    Jaskólski, W.; Pelc, M.

    The influence of magnetic field on the band structure of carbon nanotube superlattices is investigated. In particular, we study superlattices built of finite sections of (6,6) and (12,0) tubes connected by pentagon/heptagon topological defects. Magnetic field is parallel to the axis of the superlattice. We demonstrate that the superlattice band structure does not show periodicity with the flux quantum, which is typical for pure carbon nanotubes.

  3. Purification of Carbon Nanotubes by Magnetic Filtration

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Luzzi, D. E.

    2004-03-01

    Great effort has been expended in the development of methods to purify raw carbon nanotube materials by chemical treatment, washing, mechanical filtration or heat treatment in a vacuum or oxidative environment. These techniques are limited by incomplete removal of catalyst nanoparticles and by damage to the nanotubes that often results. Incomplete removal is due to the very nature of the catalyst nanoparticles which are often encapsulated inside a protective amorphous carbon or graphitic coating. We have applied magnetic filtration as a means to effectively remove the ferromagnetic catalyst nanoparticles achieving reductions of >90% by weight. In this method, SWNT solution is filtered through a column containing Fe or Ni beads in the presence of a magnetic field, by which the catalyst is attracted to the beads. We present the efficacy of various purification schemes using magnetic filtration alone, or combined with chemical-based or annealing-based oxidative treatments. The quality of the nanotube materials is quantitatively assessed using Raman spectroscopy, thermo-gravimetric analysis and electron microscopy.

  4. Chemical method of filling carbon nanotubes with magnetic material

    NASA Astrophysics Data System (ADS)

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

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

  5. Nickel clusters embedded in carbon nanotubes as high performance magnets

    NASA Astrophysics Data System (ADS)

    Shiozawa, Hidetsugu; Briones-Leon, Antonio; Domanov, Oleg; Zechner, Georg; Sato, Yuta; Suenaga, Kazu; Saito, Takeshi; Eisterer, Michael; Weschke, Eugen; Lang, Wolfgang; Peterlik, Herwig; Pichler, Thomas

    2015-10-01

    Ensembles of fcc nickel nanowires have been synthesized with defined mean sizes in the interior of single-wall carbon nanotubes. The method allows the intrinsic nature of single-domain magnets to emerge with large coercivity as their size becomes as small as the exchange length of nickel. By means of X-ray magnetic circular dichroism we probe electronic interactions at nickel-carbon interfaces where nickel exhibit no hysteresis and size-dependent spin magnetic moment. A manifestation of the interacting two subsystems on a bulk scale is traced in the nanotube’s magnetoresistance as explained within the framework of weak localization.

  6. Nickel clusters embedded in carbon nanotubes as high performance magnets

    PubMed Central

    Shiozawa, Hidetsugu; Briones-Leon, Antonio; Domanov, Oleg; Zechner, Georg; Sato, Yuta; Suenaga, Kazu; Saito, Takeshi; Eisterer, Michael; Weschke, Eugen; Lang, Wolfgang; Peterlik, Herwig; Pichler, Thomas

    2015-01-01

    Ensembles of fcc nickel nanowires have been synthesized with defined mean sizes in the interior of single-wall carbon nanotubes. The method allows the intrinsic nature of single-domain magnets to emerge with large coercivity as their size becomes as small as the exchange length of nickel. By means of X-ray magnetic circular dichroism we probe electronic interactions at nickel-carbon interfaces where nickel exhibit no hysteresis and size-dependent spin magnetic moment. A manifestation of the interacting two subsystems on a bulk scale is traced in the nanotube’s magnetoresistance as explained within the framework of weak localization. PMID:26459370

  7. Magnetic nanotubes

    DOEpatents

    Matsui, Hiroshi; Matsunaga, Tadashi

    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.

  8. Microwave absorption in nanocomposite material of magnetically functionalized carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Labunov, V. A.; Danilyuk, A. L.; Prudnikava, A. L.; Komissarov, I.; Shulitski, B. G.; Speisser, C.; Antoni, F.; Le Normand, F.; Prischepa, S. L.

    2012-07-01

    The interaction of electromagnetic radiation in X and Ka bands with magnetic nanocomposite of disordered carbon nanotubes arrays has been investigated both experimentally and theoretically. Samples were synthesized on the quartz reactor walls by decomposition of ferrocene and xylene which provided random intercalation of iron phase nanoparticles in carbon nanotube array. The exhaustive characterization of the samples by means of the scanning electron microscopy, Raman spectroscopy, and x-ray photoemission spectroscopy was performed. It was found that the absorption of the electromagnetic wave monotonically increases with the frequency. To describe these experimental data, we extended the Bruggeman effective medium theory to a more complex case of a magnetic nanocomposite with randomly distributed spherical ferromagnetic nanoparticles in a conducting medium. The essential feature of the developed model is the consideration of the complex nature of the studied material. In particular, such important parameters as magnetic and dielectric properties of both the carbon nanotube medium and the nanoparticles, the volume concentration and the dimensions of the nanoparticles, the wave impedance of the resistive-capacitive shells of the conductive nanoparticles are explicitly taken into account in our model. Moreover, analysing the experimental results, we were able to obtain the frequency dependencies of permittivity and permeability of the studied nanocomposite.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. 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.

  11. 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

  12. Sensitive magnetic force detection with a carbon nanotube resonator

    SciTech Connect

    Willick, Kyle; Haapamaki, Chris; Baugh, Jonathan

    2014-03-21

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

  13. Magnetism for understanding catalyst analysis of purified carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Bellouard, Christine; Mercier, Guillaume; Cahen, Sébastien; Ghanbaja, Jaafar; Medjahdi, Ghouti; Gleize, Jérôme; Lamura, Gianrico; Hérold, Claire; Vigolo, Brigitte

    2016-08-01

    The precise quantification of catalyst residues in purified carbon nanotubes is often a major issue in view of any fundamental and/or applicative studies. More importantly, since the best CNTs are successfully grown with magnetic catalysts, their quantification becomes strictly necessary to better understand intrinsic properties of CNT. For these reasons, we have deeply analyzed the catalyst content remained in nickel-yttrium arc-discharge single walled carbon nanotubes purified by both a chlorine-gas phase and a standard acid-based treatment. The study focuses on Ni analysis which has been investigated by transmission electron microscopy, X-ray diffraction, thermogravimetry analysis, and magnetic measurements. In the case of the acid-based treatment, all quantifications result in a decrease of the nanocrystallized Ni by a factor of two. In the case of the halogen gas treatment, analysis and quantification of Ni content is less straightforward: a huge difference appears between X-ray diffraction and thermogravimetry results. Thanks to magnetic measurements, this disagreement is explained by the presence of Ni2+ ions, belonging to NiCl2 formed during the Cl-based purification process. In particular, NiCl2 compound appears under different magnetic/crystalline phases: paramagnetic or diamagnetic, or well intercalated in between carbon sheets with an ordered magnetic phase at low temperature.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  15. Nonmagnetic carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lipert, Kamil; Kretzschmar, Florian; Ritschel, Manfred; Leonhardt, Albrecht; Klingeler, Rüdiger; Büchner, Bernd

    2009-03-01

    We have synthesized by chemical vapor deposition (CVD) single-, double-, and multiwalled carbon nanotubes without magnetic impurities. In particular, we have applied a rhenium-based CVD technique yielding nonmagnetic carbon nanotubes with diamagnetic Re particles. In addition, carbon nanotubes prepared with iron as catalyst particles are annealed at very high temperatures in which the catalyst material is completely vaporized, while the carbon nanotubes are structurally preserved. Detailed magnetic studies show for both approaches a clear diamagnetic behavior typical for pure carbon nanotubes but no indication of ferromagnetic or paramagnetic material.

  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 μs. 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. Control of Magnetic Properties of Carbon Nanotubes Filled with Iron

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  18. Anomalous magnetization of a carbon nanotube as an excitonic insulator

    NASA Astrophysics Data System (ADS)

    Rontani, Massimo

    2014-11-01

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

  19. Synthesis of magnetic carbon nanotube and photocatalytic dye degradation ability.

    PubMed

    Mahmoodi, Niyaz Mohammad

    2014-09-01

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

  20. Magnetic Multi-Walled Carbon Nanotubes for Tumor Theranostics.

    PubMed

    Wang, Lei; Shi, Jinjin; Hao, Yongwei; Zhang, Panpan; Zhao, Yalin; Meng, Dehui; Li, Dong; Chang, Junbiao; Zhang, Zhenzhong

    2015-09-01

    Current diagnostic techniques do not reliably detect cancer at early stages, and traditional chemotherapy lacks specificity and causes systemic toxicity. To address these issues, multifunctional nanomaterials are becoming more widely studied as a means of cancer detection, therapy, and monitoring. Here, iron oxide (Fe3O4) nanoparticles were conjugated onto the surface of multi-walled carbon nanotubes (MWNTs), which were then modified with polyethylenimine (PEI) and polyethylene glycol (PEG) to improve their solubility and biocompatibility. Finally, human telomerase reverse transcriptase (hTERT) siRNA was loaded on the MWNT surface by electrostatic interaction to obtain a multifunctional delivery system (MWNT-Fe3O4-PEI-PEG/siRNA). This delivery system efficiently delivered siRNA, allowed targeting of certain sites by magnetic fields, facilitated photothermal heating by near infrared irradiation, and enabled magnetic resonance imaging, thereby indicating great potential for cancer theranostic applications. PMID:26485934

  1. Magnetic Multi-Walled Carbon Nanotubes for Tumor Theranostics.

    PubMed

    Wang, Lei; Shi, Jinjin; Hao, Yongwei; Zhang, Panpan; Zhao, Yalin; Meng, Dehui; Li, Dong; Chang, Junbiao; Zhang, Zhenzhong

    2015-09-01

    Current diagnostic techniques do not reliably detect cancer at early stages, and traditional chemotherapy lacks specificity and causes systemic toxicity. To address these issues, multifunctional nanomaterials are becoming more widely studied as a means of cancer detection, therapy, and monitoring. Here, iron oxide (Fe3O4) nanoparticles were conjugated onto the surface of multi-walled carbon nanotubes (MWNTs), which were then modified with polyethylenimine (PEI) and polyethylene glycol (PEG) to improve their solubility and biocompatibility. Finally, human telomerase reverse transcriptase (hTERT) siRNA was loaded on the MWNT surface by electrostatic interaction to obtain a multifunctional delivery system (MWNT-Fe3O4-PEI-PEG/siRNA). This delivery system efficiently delivered siRNA, allowed targeting of certain sites by magnetic fields, facilitated photothermal heating by near infrared irradiation, and enabled magnetic resonance imaging, thereby indicating great potential for cancer theranostic applications.

  2. Electrostatic waves in carbon nanotubes with an axial magnetic field

    SciTech Connect

    Abdikian, Alireza; Bagheri, Mehran

    2013-10-15

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

  3. Kondo phase transitions of magnetic impurities in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Fang, Tie-Feng; Sun, Qing-feng

    2013-02-01

    We propose carbon nanotubes (CNTs) with magnetic impurities as a versatile platform to achieve exciting Kondo physics, where the CNT bath is gapped by the spin-orbit interaction and renormalized by interference effects. While the strong-coupling phase is inaccessible for the special case of half-filled impurities in neutral armchair CNTs, the system in general can undergo quantum phase transitions to the Kondo ground state. The resultant position-specific phase diagrams are investigated upon variation of the CNT radius, chirality, and carrier doping, revealing several striking features, e.g., the existence of a maximal radius for nonarmchair CNTs to realize phase transitions, and an interference-induced suppression of the Kondo screening. We show that by tuning the Fermi energy via electrostatic gating, the quantum critical region can be experimentally accessed.

  4. 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.

  5. Magnetic studies of polystyrene/iron-filled multi-wall carbon nanotube composite films

    NASA Astrophysics Data System (ADS)

    Makarova, T. L.; Zakharchuk, I.; Geydt, P.; Lahderanta, E.; Komlev, A. A.; Zyrianova, A. A.; Kanygin, M. A.; Sedelnikova, O. V.; Suslyaev, V. I.; Bulusheva, L. G.; Okotrub, A. V.

    2016-10-01

    Polystyrene/iron-filled multi-wall carbon nanotube composite films were prepared by solution processing, forge-rolling and stretching methods. Elongated iron carbide nanoparticles formed because of catalytic growth are situated inside the hollow cavity of the nanotubes. Magnetic susceptibility measurements as well as records of isothermal hysteresis loops performed in three perpendicular directions of magnetic field confirmed that the nanotubes have a preferential alignment in the matrix. Strong diamagnetic anisotropy in the composites emerges not only from the MWCNTs but also from the polystyrene matrix. The polymer sticks to the honeycomb lattice through the interaction of the π-orbitals of the phenyl ring and those of the carbon nanotube, contributing to anisotropic diamagnetic response. The contribution of iron nanoparticles to overall magnetic response strongly depends on nanotube concentration in the composite as well as on matrix-filler non-covalent stacking, which influences magnetic interparticle interactions.

  6. Carbon nanotube nanoelectromechanical systems as magnetometers for single-molecule magnets.

    PubMed

    Ganzhorn, Marc; Klyatskaya, Svetlana; Ruben, Mario; Wernsdorfer, Wolfgang

    2013-07-23

    Due to outstanding mechanical and electronic properties, carbon nanotube nanoelectromechanical systems (NEMS) were recently proposed as ultrasensitive magnetometers for single-molecule magnets (SMM). In this article, we describe a noninvasive grafting of a SMM on a carbon nanotube NEMS, which conserves both the mechanical properties of the carbon nanotube NEMS and the magnetic properties of the SMM. We will demonstrate that the nonlinearity of a carbon nanotube's mechanical motion can be used to probe the reversal of a molecular spin, associated with a bis(phthalocyaninato)terbium(III) single-molecule magnet, providing an experimental evidence for the detection of a single spin by a mechanical degree of freedom on a molecular level.

  7. Alignment dynamics of single-walled carbon nanotubes in pulsed ultrahigh magnetic fields.

    PubMed

    Shaver, Jonah; Parra-Vasquez, A Nicholas G; Hansel, Stefan; Portugall, Oliver; Mielke, Charles H; von Ortenberg, Michael; Hauge, Robert H; Pasquali, Matteo; Kono, Junichiro

    2009-01-27

    We have measured the dynamic alignment properties of single-walled carbon nanotube (SWNT) suspensions in pulsed high magnetic fields through linear dichroism spectroscopy. Millisecond-duration pulsed high magnetic fields up to 56 T as well as microsecond-duration pulsed ultrahigh magnetic fields up to 166 T were used. Because of their anisotropic magnetic properties, SWNTs align in an applied magnetic field, and because of their anisotropic optical properties, aligned SWNTs show linear dichroism. The characteristics of their overall alignment depend on several factors, including the viscosity and temperature of the suspending solvent, the degree of anisotropy of nanotube magnetic susceptibilities, the nanotube length distribution, the degree of nanotube bundling, and the strength and duration of the applied magnetic field. To explain our data, we have developed a theoretical model based on the Smoluchowski equation for rigid rods that accurately reproduces the salient features of the experimental data.

  8. Probing Magnetic Susceptibility Anisotropy of Large-Diameter Armchair Carbon Nanotubes via Magnetic Linear Dichroism Spectroscopy

    NASA Astrophysics Data System (ADS)

    Haroz, Erik; Kono, Junichiro; Searles, Thomas; Tu, Xiaomin; Zheng, Ming; Fagan, Jeffrey; McGill, Stephen; Smirnov, Dmitry

    2012-02-01

    We studied magnetic susceptibility anisotropy, via magnetic linear dichroism spectroscopy, of aqueous suspensions of single-walled carbon nanotubes in high magnetic fields up to 22T using a unique magnet system (Split-Florida Helix magnet). Specifically, we measured magnetic susceptibility anisotropies, δχ, of several armchair species ranging from (5,5)-(13,13) at room temperature over an excitation wavelength range of 400-900 nm. For large diameter armchairs such as (12,12) and (13,13), we have observed some of the strongest alignment in a static magnetic field due to their large diameters. Results will be discussed in comparison with detailed calculations involving the Aharonov-Bohm effect.

  9. Magnetic interactions between vacancy-induced intrinsic magnetic impurities in single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kong, Xiao; He, Jing; Li, Yang; Kou, Su-Peng; Liang, Ying

    2016-09-01

    Spin-half paramagnetism induced by point detects was found in graphene recently, micromechanism of this magnetic response can be explained well by the intrinsic magnetic impurity theory. In this paper, we apply this theory to two types of single-walled carbon nanotubes (SWCNs) and calculate the properties of various magnetic interactions for comparison. Interestingly, magnetic interactions have different behaviors in these systems. Following our calculation, within a short length, the interactions can be suppressed by ether size effect or a tiny band gap, and then exhibit exponentially decaying. However, in the absence of a band gap, the RKKY interaction could leave a tiny tail at long range, which determines long range magnetic order. Further more, when a tiny band gap exist in the systems, the Heisenberg coupling is the dominate one due to the expanded wavefunction. According to these result, vacancy states in different types of SWCNs could form different magnetic order, bringing abundant candidates for application.

  10. Magnetic-field-enhanced synthesis of single-wall carbon nanotubes in arc discharge

    NASA Astrophysics Data System (ADS)

    Keidar, Michael; Levchenko, Igor; Arbel, Tamir; Alexander, Myriam; Waas, Anthony M.; Ostrikov, Kostya Ken

    2008-05-01

    The ability to control the properties of single-wall nanotubes (SWNTs) produced in the arc discharge is important for many practical applications. Our experiments suggest that the length of SWNTs significantly increases (up to 4000 nm), along with the purity of the carbon deposit, when the magnetic field is applied to arc discharge. Scanning electron microscopy and transmission electron microscopy analyses have demonstrated that the carbon deposit produced in the magnetic-field-enhanced arc mainly consists of the isolated and bunched SWNTs. A model of a carbon nanotube interaction and growth in the thermal plasma was developed, which considers several important effects such as anode ablation that supplies the carbon plasma in an anodic arc discharge technique, and the momentum, charge, and energy transfer processes between nanotube and plasma. It is shown that the nanotube charge with respect to the plasma as well as nanotube length depend on plasma density and electric field in the interelectrode gap. For instance, nanotube charge changes from negative to positive value with an electron density decrease. The numerical simulations based on the Monte Carlo technique were performed, which explain an increase in the nanotubes produced in the magnetic-field-enhanced arc discharge.

  11. Influence of magnetic field on the compressive behavior of carbon nanotube with magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Reddy, S. K.; Suri, A.; Misra, A.

    2013-06-01

    Carbon nanotubes (CNT) in their cellular like micro-structure have presented an excellent mechanical energy absorption capacity. Although, several efforts have been progressed to modify the CNT structure for further enhancing their energy absorption capacity but yet no report has revealed the effect of magnetic field on the mechanical behavior of as-grown CNT mat that contains magnetic iron nanoparticles in the form of decorated nanoparticles on the surface or filled inside core of the CNT. We report a significant impact of the presence of magnetic content that modifies the mechanical behavior of the entangled CNT mat in the presence of an external magnetic field. The energy absorption capacity doubles when magnetic field was applied in the radial direction of the CNT mat under uniaxial compression.

  12. Magnetoporation and magnetolysis of cancer cells via carbon nanotubes induced by rotating magnetic fields.

    PubMed

    Liu, Dun; Wang, Lijun; Wang, Zhigang; Cuschieri, Alfred

    2012-10-10

    Weak magnetic fields (40 and 75 mT) were used either to enhance cell membrane poration (magnetoporation) or to ablate cultured human tumor cells (magnetolysis) by polymer-coated multiwalled carbon nanotubes, which form rotating bundles on exposure to magnetic fields. Findings of this study have potential clinical applications including enhanced tumor cell poration for targeted cancer chemotherapy and mechanical ablation of tumors.

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

    PubMed

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

    2013-05-21

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

  14. 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

  15. Orientation control of liquid crystals using carbon-nanotube-magnetic particle hybrid materials.

    PubMed

    Jeong, Hyeon Su; Youn, Sang Cheon; Kim, Yun Ho; Jung, Hee-Tae

    2013-06-28

    We have developed a simple yet versatile method for aligning liquid crystals (LCs) by using magnetic-field oriented single-walled carbon nanotubes (SWNTs) that were modified with magnetic particles. A high degree of homeotropic/planar LC alignment was achieved by SWNTs being exposed to a very low strength magnetic field, combined with strong π-π interactions between the biphenyl group in the LCs and the wall of the SWNTs. PMID:23676827

  16. Degeneracy in carbon nanotubes under transverse magnetic δ-fields.

    PubMed

    Kuru, Ş; 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 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. PMID:26102328

  17. Dual modality photothermal OCT and magnetic resonance imaging with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Tucker-Schwartz, Jason M.; Hong, Tu; Colvin, Daniel C.; Xu, Yaqiong; Skala, Melissa C.

    2012-03-01

    Preclinical molecular imaging of cancer has the potential to increase the understanding of fundamental cancer biology, elucidate mechanisms of cancer treatment resistance, and increase effectiveness of drug candidates. Optical and magnetic resonance imaging contain complementary strengths, suitable for gaining a wealth of knowledge when combined. Here, we demonstrate the inherent contrast sensitivity of single walled carbon nanotubes to absorption based photothermal optical coherence tomography (PT-OCT), and magnetic resonance imaging spin dephasing contrast (T2). A spectral-domain OCT system was interfaced with an amplitude-modulated (100 Hz) titanium sapphire pump beam for PT-OCT imaging. MRI was performed with a commercial 4.7 T animal scanner. With both imaging tools, contrast agent signal linearity (r2 > 0.95) and nM sensitivity over background (p < 0.05) was experimentally determined with serially dilute solutions of carbon nanotubes coated in amine-terminated polyethylene glycol. The surface functionalization chemistry for carbon nanotubes is well understood, and molecular targeting has been demonstrated in vitro and in vivo, making carbon nanotubes an attractive agent for molecular imaging in preclinical models. We have demonstrated the initial characterization steps for using carbon nanotubes for multi-modality imaging with PT-OCT and MRI.

  18. Spin current generation and magnetic response in carbon nanotubes by the twisting phonon mode

    NASA Astrophysics Data System (ADS)

    Hamada, Masato; Yokoyama, Takehito; Murakami, Shuichi

    2015-08-01

    We theoretically investigate spin current and magnetic response induced by the twisting phonon mode in carbon nanotubes via the spin-rotation coupling. An effective magnetic field due to the twisting mode induces both spin and orbital magnetizations. The induced spin and orbital magnetizations have both radial and axial components. We show that ac pure spin current is generated by the twisting phonon mode. The magnitude of the spin current and orbital magnetization for a (10,10) armchair nanotube is estimated as an example. We find that the ac pure spin current is detectable in magnitude when the frequency of the twisting mode is of the order of GHz, and that the orbital magnetization is found to be larger than the spin magnetization.

  19. Linear optical response of carbon nanotubes under axial magnetic field

    NASA Astrophysics Data System (ADS)

    Moradian, Rostam; Chegel, Raad; Behzad, Somayeh

    2010-04-01

    We considered single walled carbon naotubes (SWCNTs) as real three dimensional (3D) systems in a cylindrical coordinate. The optical matrix elements and linear susceptibility, χ(ω), in the tight binding approximation in terms of one-dimensional wave vector, kz and subband index, l are calculated. In an external axial magnetic field optical frequency dependence of linear susceptibility are investigated. We found that axial magnetic field has two effects on the imaginary part of the linear susceptibility spectrum, in agreement with experimental results. The first effect is broadening and the second, splitting. Also we found that for all metallic zigzag and armchair SWCNTs, the axial magnetic field leads to the creation of a peak with energy less than 1.5 eV, contrary to what is observed in the absence of a magnetic field.

  20. 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

  1. Preparation of magnetic carbon nanotubes (Mag-CNTs) for biomedical and biotechnological applications.

    PubMed

    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

  2. Fast Characterization of Magnetic Impurities in Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  3. Cobalt nanorods fully encapsulated in carbon nanotube and magnetization measurements by off-axis electron holography

    SciTech Connect

    Fujita, Takeshi; Hayashi, Yasuhiko; Tokunaga, Tomoharu; Yamamoto, Kazuo

    2006-06-12

    Fully encapsulated face-centered-cubic (fcc) Co nanorods in multiwalled carbon nanotubes were produced by microwave plasma enhanced chemical vapor deposition. Quantitative magnetization measurements of the Co nanorods were carried out by off-axis electron holography using a theoretical cylindrical model. The component of magnetic induction was then measured to be 1.2{+-}0.1 T, which is lower than the expected saturation magnetization of fcc Co of 1.7 T. The reason for the reduced magnetic component was discussed.

  4. Anisotropic thermal property of magnetically oriented carbon nanotube polymer composites

    NASA Astrophysics Data System (ADS)

    Li, Bin; Dong, Shuai; Wang, Caiping; Wang, Xiaojie; Fang, Jun

    2016-04-01

    This paper proposes a method for preparing multi-walled carbon nanotubea/polydimethylsiloxane (MWCNTs/PDMS) composites with enhanced thermal properties by using a high magnetic field (up to 10T). The MWCNT are oriented magnetically inside a silicone by in-situ polymerization method. The anisotropic structure would be expected to produce directional thermal conductivity. This study will provide a new approach to the development of anisotropic thermal-conductive polymer composites. Systematic studies with the preparation of silicone/graphene composites corresponding to their thermal and mechanical properties are carried out under various conditions: intensity of magnetic field, time, temperature, fillings. The effect of MWCNT/graphene content and preparation procedures on thermal conductivity of composites is investigated. Dynamic mechanical analysis (DMA) is used to reveal the mechanical properties of the composites in terms of the filling contents and magnetic field strength. The scanning electron microscope (SEM) is used to observe the micro-structure of the MWCNT composites. The alignment of MWCNTs in PDMS matrix is also studied by Raman spectroscopy. The thermal conductivity measurements show that the magnetically aligned CNT-composites feature high anisotropy in thermal conductivity.

  5. Progammed synthesis of magnetic mesoporous silica coated carbon nanotubes for organic pollutant adsorption

    NASA Astrophysics Data System (ADS)

    Tong, Yue; Zhang, Min; Xia, Peixiong; Wang, Linlin; Zheng, Jing; Li, Weizhen; Xu, Jingli

    2016-05-01

    Magnetic mesoporous silica coated carbon nanotubes were produced from hydrophilic monodisperse magnetic nanoparticles decorated carbon nanotubes using well controlled programmed synthesis method and were characterized by TEM, XRD, FTIR, TGA, N2 adsorption-desorption and VSM. The well-designed mesoporous magnetic nanotubes had a large specific area, a highly open mesoporous structure and high magnetization. Firstly, SiO2-coated maghemite/CNTs nanoparticles (CNTs/Fe3O4@SiO2 composites) were synthesized by the combination of high temperature decomposition process and an sol-gel method, in which the iron acetylacetonate as well as TEOS acted as the precursor for maghemite and SiO2, respectively. The CNTs/Fe3O4@SiO2 composites revealed a core-shell structure, Then, CNTs/Fe3O4@mSiO2 was obtained by extracting cetyltrimethylammonium bromide (CTAB) via an ion-exchange procedure. The resulting composites show not only a magnetic response to an externally applied magnetic field, but also can be a good adsorbent for the organic pollutant in the ambient temperature.

  6. Carbon nanotube composite materials

    DOEpatents

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

    2015-03-24

    A material consisting essentially of a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes dissolved in a solvent. Un-functionalized carbon nanotube concentrations up to 30 wt % and hydroxylated carbon nanotube concentrations up to 40 wt % can be used with even small concentrations of each (less than 2 wt %) useful in producing enhanced conductivity properties of formed thin films.

  7. Magnetic solid-phase extraction using carbon nanotubes as sorbents: a review.

    PubMed

    Herrero-Latorre, C; Barciela-García, J; García-Martín, S; Peña-Crecente, R M; Otárola-Jiménez, J

    2015-09-10

    Magnetic solid-phase extraction (M-SPE) is a procedure based on the use of magnetic sorbents for the separation and preconcentration of different organic and inorganic analytes from large sample volumes. The magnetic sorbent is added to the sample solution and the target analyte is adsorbed onto the surface of the magnetic sorbent particles (M-SPs). Analyte-M-SPs are separated from the sample solution by applying an external magnetic field and, after elution with the appropriate solvent, the recovered analyte is analyzed. This approach has several advantages over traditional solid phase extraction as it avoids time-consuming and tedious on-column SPE procedures and it provides a rapid and simple analyte separation that avoids the need for centrifugation or filtration steps. As a consequence, in the past few years a great deal of research has been focused on M-SPE, including the development of new sorbents and novel automation strategies. In recent years, the use of magnetic carbon nanotubes (M-CNTs) as a sorption substrate in M-SPE has become an active area of research. These materials have exceptional mechanical, electrical, optical and magnetic properties and they also have an extremely large surface area and varied possibilities for functionalization. This review covers the synthesis of M-CNTs and the different approaches for the use of these compounds in M-SPE. The performance, general characteristics and applications of M-SPE based on magnetic carbon nanotubes for organic and inorganic analysis have been evaluated on the basis of more than 110 references. Finally, some important challenges with respect the use of magnetic carbon nanotubes in M-SPE are discussed.

  8. Pumping of water through carbon nanotubes by rotating electric field and rotating magnetic field

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Peng; Kong, Gao-Pan; Zhang, Xing; He, Guo-Wei

    2013-09-01

    Using molecular dynamics simulations, we demonstrate pumping of water through a carbon nanotube by applying the combination of a rotating electric field and a rotating magnetic field. The driving force is a Lorentz force generated from the motion of charges in the magnetic field, and the motion is caused by the rotation of the electric field. We find that there exits a linear relationship between the average pumping velocity v and magnetic field strength B, which can be used to control the flux of the continuous unidirectional water flow. This approach is expected to be used in liquid circulation without a pressure gradient.

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

    PubMed

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

    2011-08-01

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

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

    SciTech Connect

    Bagheri, Mehran; Abdikian, Alireza

    2014-04-15

    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.

  11. Nontrivial magnetoresistive behavior of a single-wall carbon nanotube with an attached molecular magnet

    NASA Astrophysics Data System (ADS)

    Płomińska, Anna; Weymann, Ireneusz

    2015-11-01

    The spin-resolved transport properties of a single-wall carbon nanotube quantum dot, with an attached single molecular magnet, are studied theoretically. With the aid of the real-time diagrammatic technique in the lowest-order perturbation expansion with respect to the tunnel coupling, the current, differential conductance, and the tunnel magnetoresistance (TMR) are determined in both the linear and nonlinear response regimes. It is shown that transport properties depend greatly on both the shell filling sequence of the carbon nanotube and the type of exchange interaction between the molecular magnet and nanotube. This results in highly nontrivial behavior of the TMR, which is especially visible in the low bias voltage regime. Depending on the gate voltage and parameters of the system, we find transport regimes where either a greatly enhanced or negative TMR develops. The mechanism leading to such behavior is associated with nonequilibrium spin accumulation, which builds up in the antiparallel magnetic configuration of the device. We show that it is crucial whether the spin accumulation occurs in the highest-weight spin states or in states with lower spin values. While in the former case it leads to enhanced TMR, in the latter case it may result in negative tunnel magnetoresistance. In addition, we analyze how the above effects depend on the magnitude of the molecular magnet's spin, and show that this dependence is generally nonmonotonic.

  12. Highly efficient extraction of cellular nucleic acid associated proteins in vitro with magnetic oxidized carbon nanotubes.

    PubMed

    Zhang, Yi; Hu, Zhengyan; Qin, Hongqiang; Wei, Xiaoluan; Cheng, Kai; Liu, Fangjie; Wu, Ren'an; Zou, Hanfa

    2012-12-01

    Nucleic acid associated proteins (NAaP) play the essential roles in gene regulation and protein expression. The global analysis of cellular NAaP would give a broad insight to understand the interaction between nucleic acids and the associated proteins, such as the important proteinous regulation factors on nucleic acids. Proteomic analysis presents a novel strategy to investigate a group of proteins. However, the large scale analysis of NAaP is yet impossible due to the lack of approaches to harvest target protein groups with a high efficiency. Herein, a simple and efficient method was developed to collect cellular NAaP using magnetic oxidized carbon nanotubes based on the strong interaction between carbon nanotubes and nucleic acids along with corresponding associated proteins. We found that the magnetic oxidized carbon nanotubes demonstrated a nearly 100% extraction efficiency for intracellular nucleic acids from cells in vitro. Importantly, the proteins associated on nucleic acids could be highly efficiently harvested using magnetic oxidized carbon nanotubes due to the binding of NAaP on nucleic acids. 1594 groups of nuclear NAaP and 2595 groups of cellular NAaP were extracted and identified from about 1,000,000 cells, and 803 groups of NAaP were analyzed with only about 10,000 cells, showing a promising performance for the proteomic analysis of NAaP from minute cellular samples. This highly efficient extraction strategy for NAaP is a simple approach to identify cellular nucleic acid associated proteome, and we believed this strategy could be further applied in systems biology to understand the gene expression and regulation.

  13. Selective extraction of gallic acid in pomegranate rind using surface imprinting polymers over magnetic carbon nanotubes.

    PubMed

    Hao, Yi; Gao, Ruixia; Liu, Dechun; Tang, Yuhai; Guo, Zengjun

    2015-10-01

    A novel surface imprinting polymer based on magnetic carbon nanotubes was prepared using dendritic polyethyleneimine as functional monomer to amplify the number of imprinted cavities. The characteristics of resulting polymers were evaluated by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM). Results suggest that magnetic nanoparticles are deposited onto the surface of multiwalled carbon nanotubes and the imprinted shell is coated on the surface of magnetic carbon nanotubes with a thickness of approximately 8 nm. Magnetic imprinted polymers are sensitive to magnetic fields and can be easily separated within 3 s using an external magnet. The adsorption results indicate that the obtained imprinted polymers have fast kinetics, an ultrahigh adsorption capacity of 479.9 mg g(-1), and satisfactory selectivity towards the template molecule. The prepared materials have excellent stability with no obvious deterioration after six adsorption-regeneration cycles. In addition, a method for determination of gallic acid (GA) in pomegranate rind was developed, using a combination of the prepared polymers used as solid-phase extraction (SPE) sorbents and high-performance liquid chromatography (HPLC) for rapid isolation and determination of GA. The limit of detection of the proposed method is 0.001 μg mL(-1), and the intra and inter-day relative standard deviations (RSDs) are lower than 3.8% and 5.3%, respectively. The recoveries of GA from pomegranate rind extract are in the range 98.2-103.6% with RSDs lower than 4.3%.

  14. Measurement of magnetic anisotropy of multiwalled carbon nanotubes in nematic host

    NASA Astrophysics Data System (ADS)

    Cirtoaje, Cristina; Petrescu, Emil

    2016-10-01

    The magnetic anisotropy of multiwalled carbon nanotubes (MWCNT-s) is measured using their dispersion in nematic liquid crystal (NLC). Due to their ability to align themselves with inserted nano-particles, NLC are very useful for the study of the physical properties of MWCNT as well as for other micro or nano-particles. Thus an organized system is obtained from the beginning and the influence of initial random orientation is considerably reduced. The average magnetic anisotropy of MWCNT dispersed in NLC was calculated from the system relaxation time and the obtained value (6.61 ×10-5) was in good agreement with other reported results.

  15. Low temperature magnetic phase transition and interlayer coupling in double-wall carbon nanotubes

    SciTech Connect

    Diamantopoulou, A.; Glenis, S.; Likodimos, V.; Guskos, N.

    2014-08-28

    The magnetic properties of double wall carbon nanotubes (DWCNTs) were investigated using electron spin resonance (ESR) spectroscopy. An asymmetric resonance line of low intensity was identified and analyzed by the superimposition of a narrow and a broad metallic lineshape, attributed to the distinct contributions of defect spins located on the inner and outer DWCNTs shells. The spin susceptibilities of both ESR components revealed a ferromagnetic phase transition at low temperatures (T < 10 K) with small variation in the corresponding Curie-Weiss temperatures, approaching closely that of metallic single wall carbon nanotubes. Interlayer coupling between the DWCNT layers is suggested to effectively reduce the difference between the transition temperatures for the inner and outer shells and enhance spin-spin interactions between defect spins via the RKKY-type interaction of localized spins with conduction electrons.

  16. Magnetic molecularly imprinted polydopamine nanolayer on multiwalled carbon nanotubes surface for protein capture.

    PubMed

    Yin, Yuli; Yan, Liang; Zhang, Zhaohui; Wang, Jing

    2015-11-01

    A novel, facile and low cost process for imprinting protein on the surface of magnetic multiwalled carbon nanotubes (MMWNTs) was developed using human serum albumin (HSA) as the template and dopamine as the functional monomer. The magnetic imprinted polymers were characterized with transmission electron microscope (TEM), scanning electron microscope (SEM), Fourier-transform infrared spectrometry (FT-IR), vibrating sample magnetometer (VSM) and thermogravimetric analysis (TGA) in detail. The maximum adsorption capacity of the magnetic imprinted polymers toward HSA was 66.23 mg g(-1) and it took 20 min to achieve the adsorption equilibrium. The magnetic imprinted polymers exhibited the specific selective adsorption toward HSA. Coupled with high performance liquid chromatography (HPLC) analysis, the magnetic imprinted polymers were used to solid-phase extract and detect HSA in urine samples successfully with the recoveries of 91.95-97.8%.

  17. Carbon nanotube nanoelectrode arrays

    DOEpatents

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

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

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

    PubMed

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

    2011-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  1. 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.

  2. 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.

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

    PubMed

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

    2014-01-01

    Selective enrichment of phosphoproteins or phosphopeptides from complex mixtures is essential for mass spectrometry (MS)-based phosphoproteomics. In this work, for the first time, titania nanoparticles coated magnetic carbon nanotubes (denoted as MagCNTs@TiO₂ composites) were synthesized through a facile but effective solvothermal reaction for selective enrichment of phosphopeptides. The MagCNTs@TiO₂ material demonstrated low limit of detection (20 fmol), along with an exceptional great specificity to capture phosphopeptides from a tryptic digest of the mixture of a nonphosphorylated protein BSA and a phosphorylated protein β-casein with molar ratios of BSA/β-casein up to 200:1. In addition, the high magnetic susceptibility allowed convenient separation of the target peptides by magnetic separation. Experimental results demonstrated that the MagCNTs@TiO₂ composites showed excellent potential for the selective enrichment of phosphopeptides for MS analysis. PMID:24274265

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  5. 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.

  6. Manifestation of coherent magnetic anisotropy in a carbon nanotube matrix with low ferromagnetic nanoparticle content

    NASA Astrophysics Data System (ADS)

    Danilyuk, A. L.; Komissarov, I. V.; Labunov, V. A.; Le Normand, F.; Derory, A.; Hernandez, J. M.; Tejada, J.; Prischepa, S. L.

    2015-02-01

    The influence of the magnetic medium can lead to peculiar interaction between ferromagnetic nanoparticles (NPs). Most research in this area involves analysis of the interplay between magnetic anisotropy and exchange coupling. Increasing the average interparticle distance leads to the dominant role of the random magnetic anisotropy. Here we study the interparticle interaction in a carbon nanotube (CNT) matrix with low ferromagnetic NP content. Samples were synthesized by floating catalyst chemical vapor deposition. We found that below some critical NP concentration, when NPs are intercalated only inside CNTs, and at low temperatures, the extended magnetic order, of up to 150 nm, presents in our samples. It is shown by analyzing the correlation functions of the magnetic anisotropy axes that the extended order is not simply due to random anisotropy but is associated with the coherent magnetic anisotropy, which is strengthened by the CNT alignment. With increasing temperature the extended magnetic order is lost. Above the critical NP concentration, when NPs start to be intercalated not only into inner CNT channels, but also outside CNTs, the coherent anisotropy weakens and the exchange coupling dominates in the whole temperature range. We can make a connection with the various correlation functions using the generalized expression for the law of the approach to saturation and show that these different correlation functions reflect the peculiarities in the interparticle interaction inside CNTs. Moreover, we can extract such important micromagnetic parameters like the exchange field, local fields of random and coherent anisotropies, as well as their temperature and NP concentration dependencies.

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

    PubMed

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

    2013-06-26

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

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

    PubMed

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

    2014-05-15

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

  9. Magneto-conductivity and magnetically-controlled nonlinear optical transmittance in multi-wall carbon nanotubes.

    PubMed

    García-Merino, J A; Martínez-González, C L; San Miguel, C R Torres; Trejo-Valdez, M; Martínez-Gutiérrez, H; Torres-Torres, C

    2016-08-22

    The impact of vectorial magnetic field effects on electrical conductivity and nonlinear optical transmittance exhibited by multi-wall carbon nanotubes was studied. The samples were synthetized by an aerosol pyrolysis processing route in a thin film form. Optical signals in a two-wave mixing configuration allowed us to identify two orthogonal directions of propagation for a magnetic field travelling through the nanomaterials studied. A selective modification in optical absorption was considered to be induced by magnetic perturbations in the sample. Standard optical Kerr gate measurements were carried out for exploring the third order nonlinear optical behavior of the film. A capacitive effect influenced by optical and magnetic excitations was distinguished to be characteristic of the sample. Magneto-quantum conductivity sensitive to the direction of an external magnetic field interacting with the tubes was analyzed. Magnetically-induced changes in electronic band parameters seem to be the main responsible for the optical and electrical modulation observed in the nanostructures. Immediate applications for developing magneto-optical and magneto-electrical functions can be contemplated. PMID:27557232

  10. 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.

  11. Magnetically anisotropic additive for scalable manufacturing of polymer nanocomposite: iron-coated carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yamamoto, Namiko; Manohara, Harish; Platzman, Ellen

    2016-02-01

    Novel nanoparticles additives for polymer nanocomposites were prepared by coating carbon nanotubes (CNTs) with ferromagnetic iron (Fe) layers, so that their micro-structures can be bulk-controlled by external magnetic field application. Application of magnetic fields is a promising, scalable method to deliver bulk amount of nanocomposites while maintaining organized nanoparticle assembly throughout the uncured polymer matrix. In this work, Fe layers (˜18 nm thick) were deposited on CNTs (˜38 nm diameter and ˜50 μm length) to form thin films with high aspect ratio, resulting in a dominance of shape anisotropy and thus high coercivity of ˜50-100 Oe. The Fe-coated CNTs were suspended in water and applied with a weak magnetic field of ˜75 G, and yet preliminary magnetic assembly was confirmed. Our results demonstrate that the fabricated Fe-coated CNTs are magnetically anisotropic and effectively respond to magnetic fields that are ˜103 times smaller than other existing work (˜105 G). We anticipate this work will pave the way for effective property enhancement and bulk application of CNT-polymer nanocomposites, through controlled micro-structure and scalable manufacturing.

  12. 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

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

    PubMed

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

    2012-02-02

    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

  14. 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

  15. Influence of Magnetic Losses on Microwave Absorption by Carbon-Nanotube Nanocomposites with a Low Concentration of Ferromagnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Avramchuk, A. V.; Kasperovich, M. M.; Pevneva, N. A.; Gusinsky, A. V.; Korolik, O. V.; Tivanov, M. S.; Shulitski, B. G.; Labunov, V. A.; Danilyuk, A. L.; Komissarov, I. V.; Prischepa, S. L.

    2016-05-01

    The absorption properties of magnetic nanocomposites based on carbon nanotubes with a low concentration of ferromagnetic nanoparticles have been investigated in the 78-118 GHz frequency range. A correlation was established between the absorption properties of the nanocomposites and the character of the magnetostatic interaction between nanoparticles.

  16. Functionalized Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Lebron, Marisabel; Mintz, Eric; Meador, Michael A.; Hull, David R.; Scheiman, Daniel A.; Willis, Peter; Smalley, Richard E.

    2001-01-01

    Carbon nanotubes have created a great deal of excitement in the Materials Science community because of their outstanding mechanical, electrical, and thermal properties. Use of carbon nanotubes as reinforcements for polymers could lead to a new class of composite materials with properties, durability, and performance far exceeding that of conventional fiber reinforced composites. Organized arrays of carbon nanotubes, e.g., nanotube monolayers, could find applications as thermal management materials, light emitting devices, and sensor arrays. Carbon nanotubes could also be used as templates upon which nanotubes from other materials could be constructed. Successful use of carbon nanotubes in any of these potential applications requires the ability to control the interactions of nanotubes with each other and with other materials, e.g., a polymer matrix. One approach to achieving this control is to attach certain chemical groups to the ends and/or side-walls of the nanotubes. The nature of these chemical groups can be varied to achieve the desired result, such as better adhesion between the nanotubes and a polymer. Under a joint program between NASA Glenn, Clark Atlanta University, and Rice University researchers are working on developing a chemistry "tool-kit" that will enable the functionalization of carbon nanotubes with a variety of chemical groups. Recent results of this effort will be discussed.

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

    PubMed Central

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

    2013-01-01

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

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

    SciTech Connect

    Tooski, S. B.

    2009-10-15

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

  19. Reinforced Carbon Nanotubes.

    SciTech Connect

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi

    2005-06-28

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

  20. Quantum correlations of magnetic impurities by a multiple electron scattering in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Gamboa Angulo, Didier; Cordourier Maruri, Guillermo; de Coss Gómez, Romeo

    In this work we analyze the quantum correlations and polarizations states of magnetic impurities spins, when a multiple electron scattering was taken place. A sequence of non-correlated electrons interacts through scattering producing quantum correlation which will have an impact on the electronic transmission. We consider a short range Heisenberg interaction between ballistic electron and static impurities. We analyze the cases when the electron scattering is produce by one and two impurities, obtaining the electronic transmission rates. Concurrence and fidelity calculations are performed to obtain the level of quantum entanglement and polarization correlations. We also discuss the possible application of this model to metallic and semiconductor carbon nanotubes, which could have important implications on spintronics and quantum information devices.

  1. Novel polydopamine imprinting layers coated magnetic carbon nanotubes for specific separation of lysozyme from egg white.

    PubMed

    Gao, Ruixia; Zhang, Lili; Hao, Yi; Cui, Xihui; Liu, Dechun; Zhang, Min; Tang, Yuhai

    2015-11-01

    Novel core-shell nanocomposites, consisting of magnetic carbon nanotubes (MCNTs) core surrounded by a thin polydopamine (PDA) imprinting shell for specific recognition of lysozyme (Lyz), were fabricated for the first time. The obtained products were characterized and the results showed that the PDA layer was successfully attached onto the surface of MCNTs and the corresponding thickness of imprinting layer was just about 10nm which could enable the template access the recognition cavities easily. The polymerization conditions and adsorption performance of the resultant nanomaterials were investigated in detail. The results indicated that the obtained imprinted polymers showed fast kinetic and high affinity towards Lyz and could be used to specifically separate Lyz from real egg white. In addition, the prepared materials had excellent stability and no obvious deterioration after five adsorption-regeneration cycles. Easy preparation, rapid separation, high binding capacity, and satisfactory selectivity for the template protein make this polymer attractive in biotechnology and biosensors.

  2. A smart temperature and magnetic-responsive gating carbon nanotube membrane for ion and protein transportation.

    PubMed

    Cong, Hailin; Xu, Xiaodan; Yu, Bing; Yang, Zhaohui; Zhang, Xiaoyan

    2016-01-01

    Carbon nanotube (CNT) nanoporous membranes based on pre-aligned CNTs have superior nano-transportation properties in biological science. Herein, we report a smart temperature- and temperature-magnetic-responsive CNT nanoporous membrane (CNM) by grafting thermal-sensitive poly(N-isopropylacrylamide) (PNIPAM) and Fe3O4 nanoparticles (Fe3O4-NPs) on the open ends of pre-aligned CNTs with a diameter around 15 nm via surface-initiated atom transfer radical polymerization (SI-ATRP) method. The inner cavity of the modified CNTs in the membrane is designed to be the only path for ion and protein transportation, and its effective diameter with a variation from ~5.7 nm to ~12.4 nm can be reversible tuned by temperature and magnetic field. The PNIPAM modified CNM (PNIPAM-CNM) and PNIPAM magnetic nanoparticles modified CNM (PNIPAM-MAG-CNM) exhibit excellent temperature- or temperature-magnetic-responsive gating property to separate proteins of different sizes. The PNIPAM-CNMs and PNIPAM-MAG-CNMs have potential applications in making artificial cells, biosensors, bioseparation and purification filters. PMID:27535103

  3. A smart temperature and magnetic-responsive gating carbon nanotube membrane for ion and protein transportation

    NASA Astrophysics Data System (ADS)

    Cong, Hailin; Xu, Xiaodan; Yu, Bing; Yang, Zhaohui; Zhang, Xiaoyan

    2016-08-01

    Carbon nanotube (CNT) nanoporous membranes based on pre-aligned CNTs have superior nano-transportation properties in biological science. Herein, we report a smart temperature- and temperature-magnetic-responsive CNT nanoporous membrane (CNM) by grafting thermal-sensitive poly(N-isopropylacrylamide) (PNIPAM) and Fe3O4 nanoparticles (Fe3O4-NPs) on the open ends of pre-aligned CNTs with a diameter around 15 nm via surface-initiated atom transfer radical polymerization (SI-ATRP) method. The inner cavity of the modified CNTs in the membrane is designed to be the only path for ion and protein transportation, and its effective diameter with a variation from ~5.7 nm to ~12.4 nm can be reversible tuned by temperature and magnetic field. The PNIPAM modified CNM (PNIPAM-CNM) and PNIPAM magnetic nanoparticles modified CNM (PNIPAM-MAG-CNM) exhibit excellent temperature- or temperature-magnetic-responsive gating property to separate proteins of different sizes. The PNIPAM-CNMs and PNIPAM-MAG-CNMs have potential applications in making artificial cells, biosensors, bioseparation and purification filters.

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

    SciTech Connect

    Hajiheidari, F.; Khoshnevisan, B.; Hashemifar, S. J.

    2014-06-21

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

  5. A smart temperature and magnetic-responsive gating carbon nanotube membrane for ion and protein transportation

    PubMed Central

    Cong, Hailin; Xu, Xiaodan; Yu, Bing; Yang, Zhaohui; Zhang, Xiaoyan

    2016-01-01

    Carbon nanotube (CNT) nanoporous membranes based on pre-aligned CNTs have superior nano-transportation properties in biological science. Herein, we report a smart temperature- and temperature-magnetic-responsive CNT nanoporous membrane (CNM) by grafting thermal-sensitive poly(N-isopropylacrylamide) (PNIPAM) and Fe3O4 nanoparticles (Fe3O4-NPs) on the open ends of pre-aligned CNTs with a diameter around 15 nm via surface-initiated atom transfer radical polymerization (SI-ATRP) method. The inner cavity of the modified CNTs in the membrane is designed to be the only path for ion and protein transportation, and its effective diameter with a variation from ~5.7 nm to ~12.4 nm can be reversible tuned by temperature and magnetic field. The PNIPAM modified CNM (PNIPAM-CNM) and PNIPAM magnetic nanoparticles modified CNM (PNIPAM-MAG-CNM) exhibit excellent temperature- or temperature-magnetic-responsive gating property to separate proteins of different sizes. The PNIPAM-CNMs and PNIPAM-MAG-CNMs have potential applications in making artificial cells, biosensors, bioseparation and purification filters. PMID:27535103

  6. 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

  7. 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.

  8. Removal of oil droplets from contaminated water using magnetic carbon nanotubes.

    PubMed

    Wang, Haitao; Lin, Kun-Yi; Jing, Benxin; Krylova, Galyna; Sigmon, Ginger E; McGinn, Paul; Zhu, Yingxi; Na, Chongzheng

    2013-08-01

    Water contaminated by oil and gas production poses challenges to the management of America's water resources. Here we report the design, fabrication, and laboratory evaluation of multi-walled carbon nanotubes decorated with superparamagnetic iron-oxide nanoparticles (SPIONs) for oil-water separation. As revealed by confocal laser-scanning fluorescence microscopy, the magnetic carbon nanotubes (MCNTs) remove oil droplets through a two-step mechanism, in which MCNTs are first dispersed at the oil-water interface and then drag the droplets with them out of water by a magnet. Measurements of removal efficiency with different initial oil concentration, MCNT dose, and mixing time show that kinetics and equilibrium of the separation process can be described by the Langmuir model. Separation capacity qt is a function of MCNT dose m, mixing time t, and residual oil concentration Ce at equilibrium: [Formula in text] where qmax, kw, and K are maximum separation capacity, wrapping rate constant, and equilibrium constant, respectively. Least-square regressions using experimental data estimate qmax = 6.6(± 0.6) g-diesel g-MCNT(-1), kw = 3.36(± 0.03) L g-diesel(-1) min(-1), and K = 2.4(± 0.2) L g-diesel(-1). For used MCNTs, we further show that over 80% of the separation capacity can be restored by a 10 min wash with 1 mL ethanol for every 6 mg MCNTs. The separation by reusable MCNTs provides a promising alternative strategy for water treatment design complementary to existing ones such as coagulation, adsorption, filtration, and membrane processes.

  9. Removal of oil droplets from contaminated water using magnetic carbon nanotubes.

    PubMed

    Wang, Haitao; Lin, Kun-Yi; Jing, Benxin; Krylova, Galyna; Sigmon, Ginger E; McGinn, Paul; Zhu, Yingxi; Na, Chongzheng

    2013-08-01

    Water contaminated by oil and gas production poses challenges to the management of America's water resources. Here we report the design, fabrication, and laboratory evaluation of multi-walled carbon nanotubes decorated with superparamagnetic iron-oxide nanoparticles (SPIONs) for oil-water separation. As revealed by confocal laser-scanning fluorescence microscopy, the magnetic carbon nanotubes (MCNTs) remove oil droplets through a two-step mechanism, in which MCNTs are first dispersed at the oil-water interface and then drag the droplets with them out of water by a magnet. Measurements of removal efficiency with different initial oil concentration, MCNT dose, and mixing time show that kinetics and equilibrium of the separation process can be described by the Langmuir model. Separation capacity qt is a function of MCNT dose m, mixing time t, and residual oil concentration Ce at equilibrium: [Formula in text] where qmax, kw, and K are maximum separation capacity, wrapping rate constant, and equilibrium constant, respectively. Least-square regressions using experimental data estimate qmax = 6.6(± 0.6) g-diesel g-MCNT(-1), kw = 3.36(± 0.03) L g-diesel(-1) min(-1), and K = 2.4(± 0.2) L g-diesel(-1). For used MCNTs, we further show that over 80% of the separation capacity can be restored by a 10 min wash with 1 mL ethanol for every 6 mg MCNTs. The separation by reusable MCNTs provides a promising alternative strategy for water treatment design complementary to existing ones such as coagulation, adsorption, filtration, and membrane processes. PMID:23582309

  10. Magnetic field asymmetry and high temperature magnetoresistance in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cobden, David

    2006-03-01

    The length scales and scattering processes in the one-dimensional electron system in single-walled carbon nanotubes remain only partially understood. Measuring the magnetoresistance, in both linear and nonlinear response, is a way to investigate these processes. In disordered nanotubes with ballistic paths much shorter than the length, we observe magnetoresistance in the metallic regime which at low temperatures resembles the universal fluctuations and weak localization seen in higher dimensional metals. A parabolic magnetoresistance persists at room temperature, indicating a significant role for phase coherence and/or interactions at high temperatures. While the linear resistance of a two-terminal sample must be an even function of magnetic field B by Onsager's principle, the nonlinear resistance need not be. Importantly, the B-asymmetric nonlinear terms can in principle be used to infer the strength of electron-electron interactions in the sample [1]. We have therefore also measured in detail the lowest order B-asymmetric current contributions, with a focus on the B-linear term. This has apparently not been done before in any system. Consistent with general theory, at high temperatures the term is small and has a constant sign independent of Fermi energy. At low temperatures it grows and develops mesoscopic fluctuations. Although these result imply that interactions are involved in the transport, calculations specific to nanotubes are needed in order to extract interaction parameters. This work was done by the authors of Ref [2]. References: [1] E.L. Ivchenko and B. Spivak, Phys. Rev. B 66, 155404 (2002); [2] Jiang Wei, Michael Shimogawa, Zenghui Wang, Iuliana Radu, Robert Dormaier, and David H. Cobden, Phys. Rev. Lett. (Dec. 2005) (cond-mat/0506275).

  11. Electrodeposition of catalytic and magnetic gold nanoparticles on dendrimer-carbon nanotube layer-by-layer films.

    PubMed

    Siqueira, José R; Gabriel, Rayla C; Zucolotto, Valtencir; Silva, Anielle C A; Dantas, Noelio O; Gasparotto, Luiz H S

    2012-11-01

    Magnetic and catalytic gold nanoparticles were electrodeposited through potential pulse on dendrimer-carbon nanotube layer-by-layer (LbL) films. A plasmon absorption band at about 550 nm revealed the presence of nanoscale gold in the film. The location of the Au nanoparticles in the film was clearly observed by selecting the magnetic force microscopy mode. To our knowledge, this is the first report on the electrochemical synthesis of magnetic Au nanoparticles. In addition to the magnetic properties, the Au nanoparticles also exhibited high catalytic activity towards ethanol and glycerol oxidation in alkaline medium. PMID:23007196

  12. Electrodeposition of catalytic and magnetic gold nanoparticles on dendrimer-carbon nanotube layer-by-layer films.

    PubMed

    Siqueira, José R; Gabriel, Rayla C; Zucolotto, Valtencir; Silva, Anielle C A; Dantas, Noelio O; Gasparotto, Luiz H S

    2012-11-01

    Magnetic and catalytic gold nanoparticles were electrodeposited through potential pulse on dendrimer-carbon nanotube layer-by-layer (LbL) films. A plasmon absorption band at about 550 nm revealed the presence of nanoscale gold in the film. The location of the Au nanoparticles in the film was clearly observed by selecting the magnetic force microscopy mode. To our knowledge, this is the first report on the electrochemical synthesis of magnetic Au nanoparticles. In addition to the magnetic properties, the Au nanoparticles also exhibited high catalytic activity towards ethanol and glycerol oxidation in alkaline medium.

  13. Magnetic graphene-carbon nanotube iron nanocomposites as adsorbents and antibacterial agents for water purification.

    PubMed

    Sharma, Virender K; McDonald, Thomas J; Kim, Hyunook; Garg, Vijayendra K

    2015-11-01

    One of the biggest challenges of the 21st century is to provide clean and affordable water through protecting source and purifying polluted waters. This review presents advances made in the synthesis of carbon- and iron-based nanomaterials, graphene-carbon nanotubes-iron oxides, which can remove pollutants and inactivate virus and bacteria efficiently in water. The three-dimensional graphene and graphene oxide based nanostructures exhibit large surface area and sorption sites that provide higher adsorption capacity to remove pollutants than two-dimensional graphene-based adsorbents and other conventional adsorbents. Examples are presented to demonstrate removal of metals (e.g., Cu, Pb, Cr(VI), and As) and organics (e.g., dyes and oil) by grapheme-based nanostructures. Inactivation of Gram-positive and Gram-negative bacterial species (e.g., Escherichia coli and Staphylococcus aureus) is also shown. A mechanism involving the interaction of adsorbents and pollutants is briefly discussed. Magnetic graphene-based nanomaterials can easily be separated from the treated water using an external magnet; however, there are challenges in implementing the graphene-based nanotechnology in treating real water. PMID:26498500

  14. Magnetic graphene-carbon nanotube iron nanocomposites as adsorbents and antibacterial agents for water purification.

    PubMed

    Sharma, Virender K; McDonald, Thomas J; Kim, Hyunook; Garg, Vijayendra K

    2015-11-01

    One of the biggest challenges of the 21st century is to provide clean and affordable water through protecting source and purifying polluted waters. This review presents advances made in the synthesis of carbon- and iron-based nanomaterials, graphene-carbon nanotubes-iron oxides, which can remove pollutants and inactivate virus and bacteria efficiently in water. The three-dimensional graphene and graphene oxide based nanostructures exhibit large surface area and sorption sites that provide higher adsorption capacity to remove pollutants than two-dimensional graphene-based adsorbents and other conventional adsorbents. Examples are presented to demonstrate removal of metals (e.g., Cu, Pb, Cr(VI), and As) and organics (e.g., dyes and oil) by grapheme-based nanostructures. Inactivation of Gram-positive and Gram-negative bacterial species (e.g., Escherichia coli and Staphylococcus aureus) is also shown. A mechanism involving the interaction of adsorbents and pollutants is briefly discussed. Magnetic graphene-based nanomaterials can easily be separated from the treated water using an external magnet; however, there are challenges in implementing the graphene-based nanotechnology in treating real water.

  15. 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

    2014-01-06

    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 (ΔG°), entropy (ΔS°) and enthalpy (ΔH°) 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.

  16. 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 (ΔG°), entropy (ΔS°) and enthalpy (ΔH°) 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

  17. Synthesis and characterization of magnetic carbon nanotubes/silsesquioxane nanocomposite thin films

    NASA Astrophysics Data System (ADS)

    Osorio, Alice Gonçalves; Machado, Geraldo Beyer; Pereira, Marcelo Barbalho; Benvenutti, Edilson Valmir; Pereira, Luis Gustavo; Bergmann, Carlos Perez; Oliveira, Artur Harres de; Costa, Tania Maria Haas

    2016-05-01

    In the present study, magnetic carbon nanotubes (CNTs)/silsesquioxane nanocomposites were produced by sol-gel method and deposited as thin film by dip-coating process. Blank films and films with CNTs were characterized in order to evaluate their chemical composition and morphology. Profilometry technique showed the formation of films with 305 ± 22 nm of thickness for blank samples (without CNTs) and 173 ± 05 nm thickness for samples with CNTs. Microscopy techniques indicated the presence of CNTs well dispersed in the films and, with the aid of Raman and Fourier Transform Infrared spectroscopy, chemical composition of silsesquioxane matrix was evidenced and the presence of CNTs was confirmed in the films. Finally, the magnetic response of the deposited films was analyzed by Alternating Gradient-Field Magnetometer and results indicated that films reinforced with CNTs showed a hysteresis loop that indicates a coercivity of 103 Oe and the blank film did not show any significant response to the field applied. Hence, the authors suggest that this hybrid organic-inorganic material has potential to be applied as a new material for magnetic storage.

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  19. 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, ρ=ρ0(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 (ρ0) 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.

  20. Molecular quantum spintronics: supramolecular spin valves based on single-molecule magnets and carbon nanotubes.

    PubMed

    Urdampilleta, Matias; Nguyen, Ngoc-Viet; Cleuziou, Jean-Pierre; Klyatskaya, Svetlana; Ruben, Mario; Wernsdorfer, Wolfgang

    2011-01-01

    We built new hybrid devices consisting of chemical vapor deposition (CVD) grown carbon nanotube (CNT) transistors, decorated with TbPc(2) (Pc = phthalocyanine) rare-earth based single-molecule magnets (SMMs). The drafting was achieved by tailoring supramolecular π-π interactions between CNTs and SMMs. The magnetoresistance hysteresis loop measurements revealed steep steps, which we can relate to the magnetization reversal of individual SMMs. Indeed, we established that the electronic transport properties of these devices depend strongly on the relative magnetization orientations of the grafted SMMs. The SMMs are playing the role of localized spin polarizer and analyzer on the CNT electronic conducting channel. As a result, we measured magneto-resistance ratios up to several hundred percent. We used this spin valve effect to confirm the strong uniaxial anisotropy and the superparamagnetic blocking temperature (T(B) ~ 1 K) of isolated TbPc(2) SMMs. For the first time, the strength of exchange interaction between the different SMMs of the molecular spin valve geometry could be determined. Our results introduce a new design for operable molecular spintronic devices using the quantum effects of individual SMMs.

  1. Molecular quantum spintronics: supramolecular spin valves based on single-molecule magnets and carbon nanotubes.

    PubMed

    Urdampilleta, Matias; Nguyen, Ngoc-Viet; Cleuziou, Jean-Pierre; Klyatskaya, Svetlana; Ruben, Mario; Wernsdorfer, Wolfgang

    2011-01-01

    We built new hybrid devices consisting of chemical vapor deposition (CVD) grown carbon nanotube (CNT) transistors, decorated with TbPc(2) (Pc = phthalocyanine) rare-earth based single-molecule magnets (SMMs). The drafting was achieved by tailoring supramolecular π-π interactions between CNTs and SMMs. The magnetoresistance hysteresis loop measurements revealed steep steps, which we can relate to the magnetization reversal of individual SMMs. Indeed, we established that the electronic transport properties of these devices depend strongly on the relative magnetization orientations of the grafted SMMs. The SMMs are playing the role of localized spin polarizer and analyzer on the CNT electronic conducting channel. As a result, we measured magneto-resistance ratios up to several hundred percent. We used this spin valve effect to confirm the strong uniaxial anisotropy and the superparamagnetic blocking temperature (T(B) ~ 1 K) of isolated TbPc(2) SMMs. For the first time, the strength of exchange interaction between the different SMMs of the molecular spin valve geometry could be determined. Our results introduce a new design for operable molecular spintronic devices using the quantum effects of individual SMMs. PMID:22072910

  2. Naturally produced carbon nanotubes

    NASA Astrophysics Data System (ADS)

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

    2003-05-01

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

  3. Hemotoxicity of carbon nanotubes.

    PubMed

    Bussy, Cyrill; Methven, Laura; Kostarelos, Kostas

    2013-12-01

    Carbon nanotubes may enter into the bloodstream and interact with blood components indirectly via translocation following unintended exposure or directly after an intended administration for biomedical purposes. Once introduced into systemic circulation, nanotubes will encounter various proteins, biomolecules or cells which have specific roles in the homeostasis of the circulatory system. It is therefore essential to determine whether those interactions will lead to adverse effects or not. Advances in the understanding of how carbon nanotubes interact with blood proteins, the complement system, red blood cells and the hemostatic system are reviewed in this article. While many studies on carbon nanotube health risk assessment and their biomedical applications have appeared in the last few years, reports on the hemocompatibility of these nanomaterials remain surprisingly limited. Yet, defining the hemotoxicological profile is a mandatory step toward the development of clinically-relevant medications or contrast agents based on carbon nanotubes.

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

    SciTech Connect

    Karličić, Danilo; Cajić, Milan; Murmu, Tony; Kozić, Predrag; Adhikari, Sondipon

    2014-06-21

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

  5. Applications of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Ajayan, Pulickel M.; Zhou, Otto Z.

    Carbon nanotubes have attracted the fancy of many scientists worldwide. The small dimensions, strength and the remarkable physical properties of these structures make them a very unique material with a whole range of promising applications. In this review we describe some of the important materials science applications of carbon nanotubes. Specifically we discuss the electronic and electrochemical applications of nanotubes, nanotubes as mechanical reinforcements in high performance composites, nanotube-based field emitters, and their use as nanoprobes in metrology and biological and chemical investigations, and as templates for the creation of other nanostructures. Electronic properties and device applications of nanotubes are treated elsewhere in the book. The challenges that ensue in realizing some of these applications are also discussed from the point of view of manufacturing, processing, and cost considerations.

  6. Covalent enzyme immobilization onto carbon nanotubes using a membrane reactor

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

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

  7. Carbon Nanotube Memory Elements

    SciTech Connect

    Meunier, Vincent; Sumpter, Bobby G

    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.

  8. Transport in Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  9. 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.

  10. Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

  11. Nanotube composite carbon fibers

    NASA Astrophysics Data System (ADS)

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

    1999-08-01

    Single walled carbon nanotubes (SWNTs) were dispersed in isotropic petroleum pitch matrices to form nanotube composite carbon fibers with enhanced mechanical and electrical properties. We find that the tensile strength, modulus, and electrical conductivity of a pitch composite fiber with 5 wt % loading of purified SWNTs are enhanced by ˜90%, ˜150%, and 340% respectively, as compared to the corresponding values in unmodified isotropic pitch fibers. These results serve to highlight the potential that exits for developing a spectrum of material properties through the selection of the matrix, nanotube dispersion, alignment, and interfacial bonding.

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

    PubMed

    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. PMID:21606563

  13. 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.

  14. PEG-conjugated highly dispersive multifunctional magnetic multi-walled carbon nanotubes for cellular imaging

    NASA Astrophysics Data System (ADS)

    Khandare, Jayant J.; Jalota-Badhwar, Archana; Satavalekar, Sneha D.; Bhansali, Sujit G.; Aher, Naval D.; Kharas, Firuza; Banerjee, Shashwat S.

    2012-01-01

    We report synthesis of a highly versatile multicomponent nanosystem by covalently decorating the surface of multiwalled carbon nanotubes (CNTs) by magnetite nanoparticles (Fe3O4), poly(ethylene glycol) (PEG), and fluorophore fluorescein isothiocyanate (FITC). The resulting Fe3O4-PEG-FITC-CNT nanosystem demonstrates high dispersion ability in an aqueous medium, magnetic responsiveness, and fluorescent capacity. Transmission electron microscopy images revealed that Fe3O4 nanoparticles were well anchored onto the surfaces of the CNT. In vitro time kinetic experiments using confocal microscopy demonstrated a higher uptake of the Fe3O4-PEG-FITC-CNT nanosystem localized at the perinuclear region of MCF7 cells compared to the free FITC. In addition, the CNT nanosystem demonstrated no evidence of toxicity on cell growth. Surface conjugation of multicomponents, combined with in vitro non-toxicity, enhanced cellular uptake for FITC and site specific targeting ability makes this fluorescent Fe3O4-PEG-FITC-CNT nanosystem an ideal candidate for bioimaging, both in vitro and in vivo.

  15. Properties of K,Rb-intercalated C60 encapsulated inside carbon nanotubes called peapods derived from nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Mahfouz, R.; Bouhrara, M.; Kim, Y.; Wâgberg, T.; Goze-Bac, C.; Abou-Hamad, E.

    2015-09-01

    We present a detailed experimental study on how magnetic and electronic properties of Rb,K-intercalated C60 encapsulated inside carbon nanotubes called peapods can be derived from 13C nuclear magnetic resonance investigations. Ring currents do play a basic role in those systems; in particular, the inner cavities of nanotubes offer an ideal environment to investigate the magnetism at the nanoscale. We report the largest diamagnetic shifts down to -68.3 ppm ever observed in carbon allotropes, which is connected to the enhancement of the aromaticity of the nanotube envelope upon intercalation. The metallization of intercalated peapods is evidenced from the chemical shift anisotropy and spin-lattice relaxation (T1) measurements. The observed relaxation curves signal a three-component model with two slow and one fast relaxing components. We assigned the fast component to the unpaired electrons charged C60 that show a phase transition near 100 K. The two slow components can be rationalized by the two types of charged C60 at two different positions with a linear regime following Korringa behavior, which is typical for metallic system and allow us to estimate the density of sate at Fermi level n(EF).

  16. Experimental Study of Magnetic Multi-Walled Carbon Nanotube-Doxorubicin Conjugate in a Lymph Node Metastatic Model of Breast Cancer

    PubMed Central

    Ji, Jian; Liu, Minfeng; Meng, Yue; Liu, Runqi; Yan, Yan; Dong, Jianyu; Guo, Zhaoze; Ye, Changsheng

    2016-01-01

    Background The lymphatic system plays a significant role in the defense of a subject against breast cancer and is one of the major pathways for the metastasis of breast cancer. To improve the prognosis, many means, including surgery, radiotherapy, and chemotherapy, have been used. However, the combination of all these modalities has limited efficacy. Lymph nodes, therefore, have become an exceptionally potential target organ in cancer chemotherapy. Material/Methods A lymph node metastatic model of breast cancer was established in BALB/c mice. Magnetic multi-walled carbon nanotube carrier with good adsorption and lymph node-targeting capacity was prepared and conjugated with doxorubicin to make the magnetic multi-walled carbon nanotube-doxorubicin suspension. Dispersions of doxorubicin, magnetic multi-walled carbon nanotube-doxorubicin, and magnetic multi-walled carbon nanotube were injected into lymph node metastatic mice to compare their inhibitory effects on tumor cells in vivo. Inhibition of these dispersions on EMT-6 breast cancer cells was detected via MTT assay in vitro. Results Although no significant difference was found between the effects of doxorubicin and magnetic multi-walled carbon nanotube-doxorubicin with the same concentration of doxorubicin on EMT-6 breast cancer cells in vitro, in terms of sizes of metastatic lymph nodes and xenograft tumors, apoptosis in metastatic lymph nodes, and adverse reactions, the magnetic multi-walled carbon nanotube-doxorubicin group differed significantly from the other groups. Conclusions The magnetic multi-walled carbon nanotube-doxorubicin clearly played an inhibitory role in lymph node metastases to EMT-6 breast cancer cells. PMID:27385226

  17. Experimental Study of Magnetic Multi-Walled Carbon Nanotube-Doxorubicin Conjugate in a Lymph Node Metastatic Model of Breast Cancer.

    PubMed

    Ji, Jian; Liu, Minfeng; Meng, Yue; Liu, Runqi; Yan, Yan; Dong, Jianyu; Guo, Zhaoze; Ye, Changsheng

    2016-01-01

    BACKGROUND The lymphatic system plays a significant role in the defense of a subject against breast cancer and is one of the major pathways for the metastasis of breast cancer. To improve the prognosis, many means, including surgery, radiotherapy, and chemotherapy, have been used. However, the combination of all these modalities has limited efficacy. Lymph nodes, therefore, have become an exceptionally potential target organ in cancer chemotherapy. MATERIAL AND METHODS A lymph node metastatic model of breast cancer was established in BALB/c mice. Magnetic multi-walled carbon nanotube carrier with good adsorption and lymph node-targeting capacity was prepared and conjugated with doxorubicin to make the magnetic multi-walled carbon nanotube-doxorubicin suspension. Dispersions of doxorubicin, magnetic multi-walled carbon nanotube-doxorubicin, and magnetic multi-walled carbon nanotube were injected into lymph node metastatic mice to compare their inhibitory effects on tumor cells in vivo. Inhibition of these dispersions on EMT-6 breast cancer cells was detected via MTT assay in vitro. RESULTS Although no significant difference was found between the effects of doxorubicin and magnetic multi-walled carbon nanotube-doxorubicin with the same concentration of doxorubicin on EMT-6 breast cancer cells in vitro, in terms of sizes of metastatic lymph nodes and xenograft tumors, apoptosis in metastatic lymph nodes, and adverse reactions, the magnetic multi-walled carbon nanotube-doxorubicin group differed significantly from the other groups. CONCLUSIONS The magnetic multi-walled carbon nanotube-doxorubicin clearly played an inhibitory role in lymph node metastases to EMT-6 breast cancer cells. PMID:27385226

  18. Experimental Study of Magnetic Multi-Walled Carbon Nanotube-Doxorubicin Conjugate in a Lymph Node Metastatic Model of Breast Cancer.

    PubMed

    Ji, Jian; Liu, Minfeng; Meng, Yue; Liu, Runqi; Yan, Yan; Dong, Jianyu; Guo, Zhaoze; Ye, Changsheng

    2016-07-07

    BACKGROUND The lymphatic system plays a significant role in the defense of a subject against breast cancer and is one of the major pathways for the metastasis of breast cancer. To improve the prognosis, many means, including surgery, radiotherapy, and chemotherapy, have been used. However, the combination of all these modalities has limited efficacy. Lymph nodes, therefore, have become an exceptionally potential target organ in cancer chemotherapy. MATERIAL AND METHODS A lymph node metastatic model of breast cancer was established in BALB/c mice. Magnetic multi-walled carbon nanotube carrier with good adsorption and lymph node-targeting capacity was prepared and conjugated with doxorubicin to make the magnetic multi-walled carbon nanotube-doxorubicin suspension. Dispersions of doxorubicin, magnetic multi-walled carbon nanotube-doxorubicin, and magnetic multi-walled carbon nanotube were injected into lymph node metastatic mice to compare their inhibitory effects on tumor cells in vivo. Inhibition of these dispersions on EMT-6 breast cancer cells was detected via MTT assay in vitro. RESULTS Although no significant difference was found between the effects of doxorubicin and magnetic multi-walled carbon nanotube-doxorubicin with the same concentration of doxorubicin on EMT-6 breast cancer cells in vitro, in terms of sizes of metastatic lymph nodes and xenograft tumors, apoptosis in metastatic lymph nodes, and adverse reactions, the magnetic multi-walled carbon nanotube-doxorubicin group differed significantly from the other groups. CONCLUSIONS The magnetic multi-walled carbon nanotube-doxorubicin clearly played an inhibitory role in lymph node metastases to EMT-6 breast cancer cells.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  20. Cutting and sharpening carbon nanotubes using a carbon nanotube 'nanoknife'

    NASA Astrophysics Data System (ADS)

    Wei, Xian Long; Chen, Qing; Liu, Yang; Mao Peng, Lian

    2007-05-01

    A new method has been developed to precisely cut and to sharpen carbon nanotubes using a 'nanoknife', which is a short carbon nanotube adhered to a metal tip. The mechanism for the cutting and the sharpening was proposed to be local vaporization of carbon caused by Joule heating. The 'nanoknife' was also found useful to cut other nanotubes and nanowires. The cutting process was also found useful to construct complex carbon nanotube structures.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

  3. Carbon nanotube array based sensor

    DOEpatents

    Lee, Christopher L.; Noy, Aleksandr; Swierkowski, Stephan P.; Fisher, Karl A.; Woods, Bruce W.

    2005-09-20

    A sensor system comprising a first electrode with an array of carbon nanotubes and a second electrode. The first electrode with an array of carbon nanotubes and the second electrode are positioned to produce an air gap between the first electrode with an array of carbon nanotubes and the second electrode. A measuring device is provided for sensing changes in electrical capacitance between the first electrode with an array of carbon nanotubes and the second electrode.

  4. Templated Growth of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Siochik Emilie J. (Inventor)

    2007-01-01

    A method of growing carbon nanotubes uses a synthesized mesoporous si lica template with approximately cylindrical pores being formed there in. The surfaces of the pores are coated with a carbon nanotube precu rsor, and the template with the surfaces of the pores so-coated is th en heated until the carbon nanotube precursor in each pore is convert ed to a carbon nanotube.

  5. Microstructural investigation of magnetic CoFe2O4 nanowires inside carbon nanotubes by electron tomography.

    PubMed

    Ersen, Ovidiu; Bégin, Sylvie; Houllé, Matthieu; Amadou, Julien; Janowska, Izabela; Grenèche, Jean-Marc; Crucifix, Corinne; Pham-Huu, Cuong

    2008-04-01

    Magnetic nanowires of CoFe 2O4 were casted inside the channel of multiwall carbon nanotubes by mild chemical synthesis. A detailed investigation of these nanowires was performed using mainly the electron tomography technique; this study provides a complete characterization of their microstructure in terms of the spatial organization and the size distribution of individual particles forming the nanowire as well as its residual porosity. In particular, we have shown that the size of the CoFe 2O4 monocrystalline particles is closely dependent on the location of the particle within the nanotube, i.e., small particles close to the tube tip (5 nm) and bigger particles inside the tube channel (15 nm). As the theoretical critical size for superparamagnetic relaxation in CoFe 2O4 is estimated within the range of 4-9 nm, the size distribution obtained by 3D-TEM agrees with the Mossbauer study that suggests the presence of two different magnetic components inside the nanowire. We have shown also that, by using this preparation method and for this internal diameter of nanotube, the CoFe 2O4 nanowire exhibits a continuous structure along the tube, has a residual porosity of 38%, and can fill the tube at only 50%, parameters which influence in a significant manner the magnetic behavior of this system. PMID:18336009

  6. Fast microextraction of phthalate acid esters from beverage, environmental water and perfume samples by magnetic multi-walled carbon nanotubes.

    PubMed

    Luo, Yan-Bo; Yu, Qiong-Wei; Yuan, Bi-Feng; Feng, Yu-Qi

    2012-02-15

    In this work, magnetic carbon nanotubes (CNTs) were prepared by mixing the magnetic particles and multi-walled carbon nanotubes dispersed solutions. Due to their excellent adsorption capability towards hydrophobic compounds, the magnetic CNTs were used as adsorbent of magnetic solid-phase extraction (MSPE) to extract phthalate acid esters (PAEs), which are widely used in many consumable products with potential carcinogenic properties. By coupling MSPE with gas chromatography/mass spectrometry (GC/MS), a rapid, sensitive and cost-effective method for the analysis of PAEs was established. Our results showed that the limits of detection (LODs) of 16 PAEs ranged from 4.9 to 38 ng L(-1), which are much lower compared to the previously reported methods. And good linearities of the detection method were obtained with correlation coefficients (R(2)) between 0.9821 and 0.9993. In addition, a satisfying reproducibility was achieved by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) less than 11.7% and 14.6%, respectively. Finally, the established MSPE-GC/MS method was successfully applied to the determination of PAEs from bottled beverages, tap water and perfume samples. The recoveries of the 16 PAEs from the real samples ranged from 64.6% to 125.6% with the RSDs less than 16.5%. Taken together, the MSPE-GC/MS method developed in current study provides a new option for the detection of PAEs from real samples with complex matrices.

  7. 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.

  8. Spin splitting at the Fermi level in carbon nanotubes in the absence of a magnetic field

    NASA Astrophysics Data System (ADS)

    Cunha, Márcio M.; Brandão, Júlio; Lima, Jonas R. F.; Moraes, Fernando

    2015-11-01

    In this paper, motivated by the possibility of experimental realization, we study the low-energy electronic states of a rotating carbon nanotube within a continuum model. An effective Dirac equation in the rotating reference frame is derived and exact analytical solutions for the eigenfunctions and energy spectrum are obtained. A Zeeman-like splitting results from the coupling of rotation to total angular momentum and the previously known static results are obtained in the no rotation limit.

  9. Carbon Nanotubes for Supercapacitor

    NASA Astrophysics Data System (ADS)

    Pan, Hui; Li, Jianyi; Feng, Yuan Ping

    2010-03-01

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

  10. Carbon Nanotubes for Supercapacitor

    PubMed Central

    2010-01-01

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

  11. 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

  12. Horizontal carbon nanotube alignment.

    PubMed

    Cole, Matthew T; Cientanni, Vito; Milne, William I

    2016-09-21

    The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizontal carbon nanotube alignment. For both in and ex situ approaches, we quantitatively assess the reported linear packing densities alongside the degree of alignment possible for each of these core methodologies. PMID:27546174

  13. Horizontal carbon nanotube alignment.

    PubMed

    Cole, Matthew T; Cientanni, Vito; Milne, William I

    2016-09-21

    The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizontal carbon nanotube alignment. For both in and ex situ approaches, we quantitatively assess the reported linear packing densities alongside the degree of alignment possible for each of these core methodologies.

  14. Development of magnetic multiwalled carbon nanotubes as solid-phase extraction technique for the determination of p-hydroxybenzoates in beverage.

    PubMed

    Huang, Danni; Fu, Chinfai; Li, Zhongbo; Deng, Chunhui

    2012-07-01

    In this work, magnetic multiwalled carbon nanotubes were synthesized through a facile hydrothermal process, and then successfully used as magnetic solid-phase extraction sorbents for the determination of p-hydroxybenzoates in beverage. The prepared magnetic multiwalled carbon nanotubes presented both satisfactory superparamagnetism and strong capacity of absorption, with magnetic Fe(3)O(4) beads of 200 nm average diameters decorated at either ends of the tubes. The hybrid nanocomposites showed a high efficiency in the extraction and enrichment of p-hydroxybenzoates via π-π stacking of targeted molecules onto the polyaromatic composed surface of multiwalled carbon nanotubes, which entitled them promising magnetic solid-phase extraction sorbents for p-hydroxybenzoates at trace level from complex drink samples. By using an external magnetic field, p-hydroxybenzoates adsorbed on magnetic multiwalled carbon nanotubes could be rapidly isolated in only 30 s, and subsequently analyzed by liquid chromatography-diode array detector after elution with organic solvents. Extraction conditions such as eluting solvent, the amounts of magnetic sorbents added, pH values, adsorption and desorption time were investigated and optimized to achieve the best effect. Method validations including linearity, detection limit, and precision were also studied. The linearities were in the wide range of 0.05-500 μg/mL with correlation coefficients higher than 0.9983 for all p-hydroxybenzoates. The limits of detection were less than 20 ng/mL. Acceptable RSDs were achieved within 5-8% for all analytes. The results indicated that the proposed method based on magnetic multiwalled carbon nanotubes as magnetic solid-phase extraction absorbents was rapid, efficient, and convenient for the analysis of the targeted compounds of p-hydroxybenzoates in beverage sample.

  15. Copper-philic carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Belgamwar, Sachin U.; Sharma, Niti Nipun

    2016-04-01

    Carbon nanotube is having poor wet-ability with copper metal. Wet-ability of carbon nanotube was improved by exposing and creating more active sites on the surface of carbon nanotube. Carbon nanotubes were subjected to the prolong ultrasonication treatment of 20×103 Hz and 500W, which helped in disentanglement of carbon nanotube agglomerates and in breaking the weak bonds like pentagonal or heptagonal structure on the surface and on the CNT cap. Disentanglement of the carbon nanotube, resulted in exposing the defective sites on the surface and breaking of weak bonds, which assisted in creating the new defects on the surface. This process results in generates more active sites on the surface and it helps in improving the wet-ability of the carbon nanotube in copper.

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

    PubMed

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

    2015-01-01

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

  17. Carbon nanotube filters

    NASA Astrophysics Data System (ADS)

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

    2004-09-01

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

  18. Carbon nanotubes for microelectronics?

    PubMed

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

    2005-04-01

    Despite all prophecies of its end, silicon-based microelectronics still follows Moore's Law and continues to develop rapidly. However, the inherent physical limits will eventually be reached. Carbon nanotubes offer the potential for further miniaturization as long as it is possible to selectively deposit them with defined properties.

  19. Nitrogen doping in carbon nanotubes.

    PubMed

    Ewels, C P; Glerup, M

    2005-09-01

    Nitrogen doping of single and multi-walled carbon nanotubes is of great interest both fundamentally, to explore the effect of dopants on quasi-1D electrical conductors, and for applications such as field emission tips, lithium storage, composites and nanoelectronic devices. We present an extensive review of the current state of the art in nitrogen doping of carbon nanotubes, including synthesis techniques, and comparison with nitrogen doped carbon thin films and azofullerenes. Nitrogen doping significantly alters nanotube morphology, leading to compartmentalised 'bamboo' nanotube structures. We review spectroscopic studies of nitrogen dopants using techniques such as X-ray photoemission spectroscopy, electron energy loss spectroscopy and Raman studies, and associated theoretical models. We discuss the role of nanotube curvature and chirality (notably whether the nanotubes are metallic or semiconducting), and the effect of doping on nanotube surface chemistry. Finally we review the effect of nitrogen on the transport properties of carbon nanotubes, notably its ability to induce negative differential resistance in semiconducting tubes.

  20. Carbon nanotube actuators

    PubMed

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

    1999-05-21

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

  1. Cell nucleus targeting for living cell extraction of nucleic acid associated proteins with intracellular nanoprobes of magnetic carbon nanotubes.

    PubMed

    Zhang, Yi; Hu, Zhengyan; Qin, Hongqiang; Liu, Fangjie; Cheng, Kai; Wu, Ren'an; Zou, Hanfa

    2013-08-01

    Since nanoparticles could be ingested by cells naturally and target at a specific cellular location as designed, the extraction of intracellular proteins from living cells for large-scale analysis by nanoprobes seems to be ideally possible. Nucleic acid associated proteins (NAaP) take the crucial position during biological processes in maintaining and regulating gene structure and gene related behaviors, yet there are still challenges during the global investigation of intracellular NAaP, especially from living cells. In this work, a strategy to extract intracellular proteins from living cells with the magnetic carbon nanotube (oMWCNT@Fe3O4) as an intracellular probe is developed, to achieve the high throughput analysis of NAaP from living human hepatoma BEL-7402 cells with a mass spectrometry-based proteomic approach. Due to the specific intracellular localization of the magnetic carbon nanotubes around nuclei and its strong interaction with nucleic acids, the highly efficient extraction was realized for cellular NAaP from living cells, with the capability of identifying 2383 intracellular NAaP from only ca. 10,000 living cells. This method exhibited potential applications in dynamic and in situ analysis of intracellular proteins.

  2. The Toxicology of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  3. Charge transport and magnetic properties of coaxial composite fibrils of polypyrrole/multiwall carbon nanotubes at low temperature

    NASA Astrophysics Data System (ADS)

    Bhatia, Ravi; Sameera, I.; Prasad, V.; Menon, Reghu

    2013-04-01

    We report the low temperature electrical and magnetic properties of polypyrrole (PPy)/multiwall carbon nanotube (MWNT) coaxial composite fibrils synthesized by the electro-polymerization method. The iron-filled MWNTs were first grown by chemical vapor deposition of a mixture of liquid phase organic compound and ferrocene by the one step method. Then the PPy/MWNT fibrils were prepared by the electrochemical polymerization process. Electron microscopy studies reveal that PPy coating on the surface of nanotube is quite uniform throughout the length. The temperature dependent electrical resistivity and magnetization measurements were done from room temperature down to 5 and 10 K, respectively. The room temperature resistivity (ρ) of PPy/MWNT composite fibril sample is ˜3.8 Ωcm with resistivity ratio [R5 K/R300 K] of ˜300, and the analysis of ρ(T) in terms of reduced activation energy shows that resistivity lies in the insulating regime below 40 K. The resistivity varies according to three dimensional variable range hopping mechanism at low temperature. The magnetization versus applied field (M-H loop) data up to a field of 20 kOe are presented, displaying ferromagnetic behavior at all temperatures with enhanced coercivities ˜680 and 1870 Oe at room temperature and 10 K, respectively. The observation of enhanced coercivity is due to significant dipolar interaction among encapsulated iron nanoparticles, and their shape anisotropy contribution as well.

  4. Carbon Nanotube Purification and Functionalization

    NASA Technical Reports Server (NTRS)

    Lebron, Marisabel; Mintz, Eric; Smalley, Richard E.; Meador, Michael A.

    2003-01-01

    Carbon nanotubes have the potential to significantly enhance the mechanical, thermal, and electrical properties of polymers. However, dispersion of carbon nanotubes in a polymer matrix is hindered by the electrostatic forces that cause them to agglomerate. Chemical modification of the nanotubes is necessary to minimize these electrostatic forces and promote adhesion between the nanotubes and the polymer matrix. In a collaborative research program between Clark Atlanta University, Rice University, and NASA Glenn Research Center several approaches are being explored to chemically modify carbon nanotubes. The results of this research will be presented.

  5. Purification of Carbon Nanotubes: Alternative Methods

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  6. A rational design for the separation of metallic and semiconducting single-walled carbon nanotubes using a magnetic field

    NASA Astrophysics Data System (ADS)

    Luo, Chengzhi; Wan, Da; Jia, Junji; Li, Delong; Pan, Chunxu; Liao, Lei

    2016-06-01

    The separation of metallic (m-) and semiconducting (s-) single-walled carbon nanotubes (SWNTs) without causing contamination and damage is a major challenge for SWNT-based devices. As a facile and nondestructive tool, the use of a magnetic field could be an ideal strategy to separate m-/s-SWNTs, based on the difference of magnetic susceptibilities. Here, we designed a novel magnetic field-assisted floating catalyst chemical vapor deposition system to separate m-/s-SWNTs. Briefly, m-SWNTs are attracted toward the magnetic pole, leaving s-SWNTs on the substrate. By using this strategy, s-SWNTs with a purity of 99% could be obtained, which is enough to construct high-performance transistors with a mobility of 230 cm2 V-1 s-1 and an on/off ratio of 106. We also established a model to quantitatively calculate the percentage of m-SWNTs on the substrate and this model shows a good match with the experimental data. Furthermore, our rational design also provides a new avenue for the growth of SWNTs with specific chirality and manipulated arrangement due to the difference of magnetic susceptibilities between different diameters, chiralities, and types.The separation of metallic (m-) and semiconducting (s-) single-walled carbon nanotubes (SWNTs) without causing contamination and damage is a major challenge for SWNT-based devices. As a facile and nondestructive tool, the use of a magnetic field could be an ideal strategy to separate m-/s-SWNTs, based on the difference of magnetic susceptibilities. Here, we designed a novel magnetic field-assisted floating catalyst chemical vapor deposition system to separate m-/s-SWNTs. Briefly, m-SWNTs are attracted toward the magnetic pole, leaving s-SWNTs on the substrate. By using this strategy, s-SWNTs with a purity of 99% could be obtained, which is enough to construct high-performance transistors with a mobility of 230 cm2 V-1 s-1 and an on/off ratio of 106. We also established a model to quantitatively calculate the percentage of m

  7. Defect-Free Carbon Nanotube Coils.

    PubMed

    Shadmi, Nitzan; Kremen, Anna; Frenkel, Yiftach; Lapin, Zachary J; Machado, Leonardo D; Legoas, Sergio B; Bitton, Ora; Rechav, Katya; Popovitz-Biro, Ronit; Galvão, Douglas S; Jorio, Ado; Novotny, Lukas; Kalisky, Beena; Joselevich, Ernesto

    2016-04-13

    Carbon nanotubes are promising building blocks for various nanoelectronic components. A highly desirable geometry for such applications is a coil. However, coiled nanotube structures reported so far were inherently defective or had no free ends accessible for contacting. Here we demonstrate the spontaneous self-coiling of single-wall carbon nanotubes into defect-free coils of up to more than 70 turns with identical diameter and chirality, and free ends. We characterize the structure, formation mechanism, and electrical properties of these coils by different microscopies, molecular dynamics simulations, Raman spectroscopy, and electrical and magnetic measurements. The coils are highly conductive, as expected for defect-free carbon nanotubes, but adjacent nanotube segments in the coil are more highly coupled than in regular bundles of single-wall carbon nanotubes, owing to their perfect crystal momentum matching, which enables tunneling between the turns. Although this behavior does not yet enable the performance of these nanotube coils as inductive devices, it does point a clear path for their realization. Hence, this study represents a major step toward the production of many different nanotube coil devices, including inductors, electromagnets, transformers, and dynamos.

  8. Defect-Free Carbon Nanotube Coils.

    PubMed

    Shadmi, Nitzan; Kremen, Anna; Frenkel, Yiftach; Lapin, Zachary J; Machado, Leonardo D; Legoas, Sergio B; Bitton, Ora; Rechav, Katya; Popovitz-Biro, Ronit; Galvão, Douglas S; Jorio, Ado; Novotny, Lukas; Kalisky, Beena; Joselevich, Ernesto

    2016-04-13

    Carbon nanotubes are promising building blocks for various nanoelectronic components. A highly desirable geometry for such applications is a coil. However, coiled nanotube structures reported so far were inherently defective or had no free ends accessible for contacting. Here we demonstrate the spontaneous self-coiling of single-wall carbon nanotubes into defect-free coils of up to more than 70 turns with identical diameter and chirality, and free ends. We characterize the structure, formation mechanism, and electrical properties of these coils by different microscopies, molecular dynamics simulations, Raman spectroscopy, and electrical and magnetic measurements. The coils are highly conductive, as expected for defect-free carbon nanotubes, but adjacent nanotube segments in the coil are more highly coupled than in regular bundles of single-wall carbon nanotubes, owing to their perfect crystal momentum matching, which enables tunneling between the turns. Although this behavior does not yet enable the performance of these nanotube coils as inductive devices, it does point a clear path for their realization. Hence, this study represents a major step toward the production of many different nanotube coil devices, including inductors, electromagnets, transformers, and dynamos. PMID:26708150

  9. Electroless Co-P-Carbon Nanotube composite coating to enhance magnetic properties of grain-oriented electrical steel

    NASA Astrophysics Data System (ADS)

    Goel, Vishu; Anderson, Philip; Hall, Jeremy; Robinson, Fiona; Bohm, Siva

    2016-06-01

    The effect of Co-P-CNT coating on the magnetic properties of grain oriented electrical steel was investigated. To analyse the coating, Raman spectroscopy, Superconducting QUantum Interference Device (SQUID), single strip testing, Scanning Electron Microscopy (SEM) and talysurf surface profilometry were performed. Raman spectra showed the D and G band which corroborates the presence of Multi-Walled Carbon Nanotubes (MWCNT) in the coating. The magnetic nature of the coating was confirmed by SQUID results. Power loss results show an improvement ranging 13-15% after coating with Co-P-CNT. The resistivity of the coating was measured to be 104 μΩ cm. Loss separation graphs were plotted before and after coating to study the improvement in power loss. It was found that the coating helps in reducing the hysteresis loss. The thickness of the coating was found to be 414±40 nm. The surface profilometry results showed that the surface roughness improved after coating the sample.

  10. Carbon nanotubes on a substrate

    DOEpatents

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

    2002-03-26

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

  11. Magnetic multiwall carbon nanotubes modified with dual hydroxy functional ionic liquid for the solid-phase extraction of protein.

    PubMed

    Chen, Jing; Wang, Yuzhi; Huang, Yanhua; Xu, Kaijia; Li, Na; Wen, Qian; Zhou, Yigang

    2015-05-21

    A novel adsorbent based on silica-coated magnetic multiwall carbon nanotubes (MWCNTs) surface modified by dual hydroxy functional ionic liquid (FIL) ([OH]-FIL-m-MWCNTs@SiO2) has been designed and used for the purification of lysozyme (Lys) by magnetic solid-phase extraction (MSPE). Fourier transform infrared spectroscopy (FTIR), a vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were employed to characterize [OH]-FIL-m-MWCNTs@SiO2. After extraction, the concentration of Lys was determined by a UV-Vis spectrophotometer at 278 nm. A series of single-factor experiments were carried out to identify the optimal conditions of the extraction and the extraction amount could reach up to 94.6 mg g(-1). The RSD of the precision, the repeatability and the stability experiments were 0.37% (n = 3), 0.47% (n = 3) and 0.52% (n = 3), respectively. Comparison of [OH]-FIL-m-MWCNTs@SiO2 with silica-coated magnetic Fe3O4 (Fe3O4@SiO2), silica-coated magnetic multiwall carbon nanotubes (m-MWCNTs@SiO2) and alkyl quaternary ammonium ionic liquid-modified on m-MWCNTs@SiO2 was carried out by extracting Lys. The extraction of bovine serum albumin (BSA), trypsin (Try) and ovalbumin (OVA) was also done by the proposed method. Desorption of Lys was carried out by 0.005 mol L(-1) Na2HPO4-1 mol L(-1) NaCl as the eluent solution and the desorption ratio reached 91.6%. Nearly 97.8% of the [OH]-FIL-m-MWCNTs@SiO2 could be recovered from each run, and the extraction amount decreased less after five runs. The circular dichroism spectral experiment analysis indicated that the secondary structure of Lys was unchanged after extraction.

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

    PubMed

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

    2005-12-14

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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Carbon nanotube IR detectors (SV)

    SciTech Connect

    Leonard, F. L.

    2012-03-01

    Sandia National Laboratories (Sandia) and Lockheed Martin Corporation (LMC) collaborated to (1) evaluate the potential of carbon nanotubes as channels in infrared (IR) photodetectors; (2) assemble and characterize carbon nanotube electronic devices and measure the photocurrent generated when exposed to infrared light;(3) compare the performance of the carbon nanotube devices with that of traditional devices; and (4) develop and numerically implement models of electronic transport and opto-electronic behavior of carbon nanotube infrared detectors. This work established a new paradigm for photodetectors.

  18. 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.

  19. A rational design for the separation of metallic and semiconducting single-walled carbon nanotubes using a magnetic field.

    PubMed

    Luo, Chengzhi; Wan, Da; Jia, Junji; Li, Delong; Pan, Chunxu; Liao, Lei

    2016-07-14

    The separation of metallic (m-) and semiconducting (s-) single-walled carbon nanotubes (SWNTs) without causing contamination and damage is a major challenge for SWNT-based devices. As a facile and nondestructive tool, the use of a magnetic field could be an ideal strategy to separate m-/s-SWNTs, based on the difference of magnetic susceptibilities. Here, we designed a novel magnetic field-assisted floating catalyst chemical vapor deposition system to separate m-/s-SWNTs. Briefly, m-SWNTs are attracted toward the magnetic pole, leaving s-SWNTs on the substrate. By using this strategy, s-SWNTs with a purity of 99% could be obtained, which is enough to construct high-performance transistors with a mobility of 230 cm(2) V(-1) s(-1) and an on/off ratio of 10(6). We also established a model to quantitatively calculate the percentage of m-SWNTs on the substrate and this model shows a good match with the experimental data. Furthermore, our rational design also provides a new avenue for the growth of SWNTs with specific chirality and manipulated arrangement due to the difference of magnetic susceptibilities between different diameters, chiralities, and types.

  20. A rational design for the separation of metallic and semiconducting single-walled carbon nanotubes using a magnetic field.

    PubMed

    Luo, Chengzhi; Wan, Da; Jia, Junji; Li, Delong; Pan, Chunxu; Liao, Lei

    2016-07-14

    The separation of metallic (m-) and semiconducting (s-) single-walled carbon nanotubes (SWNTs) without causing contamination and damage is a major challenge for SWNT-based devices. As a facile and nondestructive tool, the use of a magnetic field could be an ideal strategy to separate m-/s-SWNTs, based on the difference of magnetic susceptibilities. Here, we designed a novel magnetic field-assisted floating catalyst chemical vapor deposition system to separate m-/s-SWNTs. Briefly, m-SWNTs are attracted toward the magnetic pole, leaving s-SWNTs on the substrate. By using this strategy, s-SWNTs with a purity of 99% could be obtained, which is enough to construct high-performance transistors with a mobility of 230 cm(2) V(-1) s(-1) and an on/off ratio of 10(6). We also established a model to quantitatively calculate the percentage of m-SWNTs on the substrate and this model shows a good match with the experimental data. Furthermore, our rational design also provides a new avenue for the growth of SWNTs with specific chirality and manipulated arrangement due to the difference of magnetic susceptibilities between different diameters, chiralities, and types. PMID:27315328

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

  2. Colloidally stabilized magnetic carbon nanotubes providing MRI contrast in mouse liver tumors.

    PubMed

    Liu, Yue; Muir, Benjamin W; Waddington, Lynne J; Hinton, Tracey M; Moffat, Bradford A; Hao, Xiaojuan; Qiu, Jieshan; Hughes, Timothy C

    2015-03-01

    The use of medical imaging contrast agents may lead to improved patient prognosis by potentially enabling an earlier detection of diseases and therefore an earlier initiation of treatments. In this study, we fabricated superparamagnetic iron oxide (SPIO) nanoparticles within the inner cavity of multiwalled carbon nanotubes (MWCNTs) for the first time; thereby ensuring high mechanical stability of the nanoparticles. A simple, but effective, self-assembled coating with RAFT diblock copolymers ensured the SPIO-MWCNTs have a high dispersion stability under physiological conditions. In vivo acute tolerance testing in mice showed a high tolerance dose up to 100 mg kg(-1). Most importantly, after administration of the material a 55% increase in tumor to liver contrast ratio was observed with in vivo MRI measurements compared to the preinjection image enhancing the detection of the tumor.

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

    PubMed

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

    2011-07-15

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

  4. Carbon nanotube Archimedes screws.

    PubMed

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

    2010-12-28

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

  5. Hybrid nanoparticle architecture for cellular uptake and bioimaging: direct crystallization of a polymer immobilized with magnetic nanoparticles on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Depan, D.; Misra, R. D. K.

    2012-09-01

    We describe here the success of an innovative approach of direct immobilization of magnetic nanoparticles (MNPs) onto carbon nanotubes (CNTs). The approach involved functionalization of magnetic nanoparticles and consequent covalent linkage to a copolymer (PE-b-PEG). Next, the immobilized magnetic nanoparticles on the copolymer were directly crystallized on the long axis of CNTs, where the interfacial adhesion comes from electrostatic and van der Waals interaction. The intracellular trafficking of a hybrid nanoparticle system [(PE-b-PEG)-MNP-CNT-FITC] in HeLa cells was monitored using a fluorescent marker, FITC, conjugated to the nanoparticle system. The distribution of the nanoparticle system inside cells was studied by fluorescence microscopy in a time and dose dependent manner, and it was observed that the nanoparticles are located in the cytoplasm and no apparent cell death was observed at the concentration studied. Also, the effect of an externally applied magnetic field on actin cytoskeleton, cell morphology and intracellular uptake of iron was studied. The approach described here is promising for simultaneous imaging and monitoring intracellular uptake.

  6. Dual targeted delivery of doxorubicin to cancer cells using folate-conjugated magnetic multi-walled carbon nanotubes.

    PubMed

    Lu, Yu-Jen; Wei, Kuo-Chen; Ma, Chen-Chi M; Yang, Shin-Yi; Chen, Jyh-Ping

    2012-01-01

    By combining the advantage of multi-walled carbon nanotubes (MWCNTs) and iron oxide magnetic nanoparticles (MNs), we develop a magnetic dual-targeted nanocarrier for drug delivery. MWCNTs were functionalized with poly(acrylic acid) through free radical polymerization, decorated with MNs, conjugated with a targeting ligand folic acid (FA), for loading of an anti-cancer drug doxorubicin (DOX). The proposed methodology provides dual targeted delivery of the anti-cancer drug to cancer cells under the guidance of a magnetic field and through ligand-receptor interactions. The chemico-physical properties of the nanocarrier were characterized, in addition to its drug loading efficiency and drug releasing characteristics. Doxorubicin could be loaded to MWCNTs with high efficiency via π-π stacking and hydrogen bonding and showed enhanced cytotoxicity toward U87 human glioblastoma cells compared with free DOX. From transmission electron microscopy and confocal laser scanning microscopy, we confirmed that DOX-FA-MN-MWCNT could be efficiently taken up by U87 cells with subsequent intracellular release of DOX, followed by transport of DOX into the nucleus with the nanocarrier left in the cytoplasm. These properties make the magnetic nanocarrier a potential candidate for targeted delivery of DOX for cancer treatment.

  7. Hybrid nanoparticle architecture for cellular uptake and bioimaging: direct crystallization of a polymer immobilized with magnetic nanoparticles on carbon nanotubes.

    PubMed

    Depan, D; Misra, R D K

    2012-10-21

    We describe here the success of an innovative approach of direct immobilization of magnetic nanoparticles (MNPs) onto carbon nanotubes (CNTs). The approach involved functionalization of magnetic nanoparticles and consequent covalent linkage to a copolymer (PE-b-PEG). Next, the immobilized magnetic nanoparticles on the copolymer were directly crystallized on the long axis of CNTs, where the interfacial adhesion comes from electrostatic and van der Waals interaction. The intracellular trafficking of a hybrid nanoparticle system [(PE-b-PEG)-MNP-CNT-FITC] in HeLa cells was monitored using a fluorescent marker, FITC, conjugated to the nanoparticle system. The distribution of the nanoparticle system inside cells was studied by fluorescence microscopy in a time and dose dependent manner, and it was observed that the nanoparticles are located in the cytoplasm and no apparent cell death was observed at the concentration studied. Also, the effect of an externally applied magnetic field on actin cytoskeleton, cell morphology and intracellular uptake of iron was studied. The approach described here is promising for simultaneous imaging and monitoring intracellular uptake.

  8. 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

    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

  9. 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

    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.

  10. Teslaphoresis of Carbon Nanotubes.

    PubMed

    Bornhoeft, Lindsey R; Castillo, Aida C; Smalley, Preston R; Kittrell, Carter; James, Dustin K; Brinson, Bruce E; Rybolt, Thomas R; Johnson, Bruce R; Cherukuri, Tonya K; Cherukuri, Paul

    2016-04-26

    This paper introduces Teslaphoresis, the directed motion and self-assembly of matter by a Tesla coil, and studies this electrokinetic phenomenon using single-walled carbon nanotubes (CNTs). Conventional directed self-assembly of matter using electric fields has been restricted to small scale structures, but with Teslaphoresis, we exceed this limitation by using the Tesla coil's antenna to create a gradient high-voltage force field that projects into free space. CNTs placed within the Teslaphoretic (TEP) field polarize and self-assemble into wires that span from the nanoscale to the macroscale, the longest thus far being 15 cm. We show that the TEP field not only directs the self-assembly of long nanotube wires at remote distances (>30 cm) but can also wirelessly power nanotube-based LED circuits. Furthermore, individualized CNTs self-organize to form long parallel arrays with high fidelity alignment to the TEP field. Thus, Teslaphoresis is effective for directed self-assembly from the bottom-up to the macroscale. PMID:27074626

  11. Studies of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Caneba, Gerard T.

    2005-01-01

    The fellowship experience for this summer for 2004 pertains to carbon nanotube coatings for various space-related applications. They involve the following projects: (a) EMI protection films from HiPco-polymers, and (b) Thermal protection nanosilica materials. EMI protection films are targeted to be eventually applied onto casings of laptop computers. These coatings are composites of electrically-conductive SWNTs and compatible polymers. The substrate polymer will be polycarbonate, since computer housings are typically made of carbon composites of this type of polymer. A new experimental copolymer was used last year to generate electrically-conductive and thermal films with HiPco at 50/50 wt/wt composition. This will be one of the possible formulations. Reference films will be base polycarbonate and neat HiPco onto polycarbonate films. Other coating materials that will be tried will be based on HiPco composites with commercial enamels (polyurethane, acrylic, polyester), which could be compatible with the polycarbonate substrate. Nanosilica fibers are planned for possible use as thermal protection tiles on the shuttle orbiter. Right now, microscale silica is used. Going to the nanoscale will increase the surface-volume-per-unit-area of radiative heat dissipation. Nanoscale carbon fibers/nanotubes can be used as templates for the generation of nanosilica. A sol-gel operation is employed for this purpose.

  12. Silicon Encapsulated Carbon Nanotubes

    PubMed Central

    2010-01-01

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

  13. Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  14. Functionalization of carbon nanotubes

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  15. Carbon Nanotube Interconnect

    NASA Technical Reports Server (NTRS)

    Li, Jun (Inventor); Meyyappan, Meyya (Inventor)

    2006-01-01

    Method and system for fabricating an electrical interconnect capable of supporting very high current densities ( 10(exp 6)-10(exp 10) Amps/sq cm), using an array of one or more carbon nanotubes (CNTs). The CNT array is grown in a selected spaced apart pattern, preferably with multi-wall CNTs, and a selected insulating material, such as SiOw, or SiuNv is deposited using CVD to encapsulate each CNT in the array. An exposed surface of the insulating material is planarized to provide one or more exposed electrical contacts for one or more CNTs.

  16. Effect of magnetic field on quantum state energies of an electron confined in the core of a double walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Shah, Khurshed A.; Bhat, Bashir Mohi Ud Din

    2016-10-01

    In this paper we report the effect of external magnetic field and core radius on the excited quantum state energies of an electron confined in the core of a double walled carbon nanotube. The goal is accomplished by using Wentzel-Kramers-Brillioun (WKB) approximation method within the effective mass approximation and confinement potential. All numerical analysis were carried out in a strong confinement regime. The results show that the electron energy increases with the increase in external magnetic field at a given core radii. The electron energy is also found to increase as the core radius of the CNT decreases and for core radius a > 5 nm the energy becomes almost zero. The effect of magnetic field on the excited state energies of the confined electron is more evident for smaller core radius a<1 nm. The observed results are important for calculations of spin polarized current in carbon nanotube quantum dot devices [1].

  17. Greater osteoblast and mesenchymal stem cell adhesion and proliferation on titanium with hydrothermally treated nanocrystalline hydroxyapatite/magnetically treated carbon nanotubes.

    PubMed

    Wang, Mian; Castro, Nathan J; Li, Jian; Keidar, Michael; Zhang, Lijie Grace

    2012-10-01

    With an increasingly active and aging population, a growing number of orthopedic procedures are performed annually. However, traditional orthopedic implants face many complications such as infection, implant loosening, and poor host tissue integration leading to implant failure. Metal implant materials such as titanium and its alloys are widely used in orthopedic applications mainly based on their excellent mechanical properties and biological inertness. Since human bone extracellular matrix is nanometer in dimension comprised of rich nanostructured hydroxyapatite particles and collagen nanofibers, it is highly desirable to design a biologically-inspired nanostructured coating which renders the biocompatible titanium surface into a biomimetic and bioactive interface, thus enhancing osteoblast adhesion and promoting osseointegration. For this purpose, a biomimetic nanostructured coating based on nanocrystalline hydroxyapatite and single wall carbon nanotubes was designed. Specifically, nano hydroxyapatites with good crystallinity and biomimetic dimensions were prepared via a wet chemistry method and hydrothermal treatment. Microcrystalline hydroxyapatite with larger grain sizes can be obtained without hydrothermal treatment. The carbon nanotubes with different diameter and length were synthesized via an arc plasma method in the presence or absence of a magnetic field. Transmission electron microscopy images illustrate the regular, rod-like nanocrystalline and biomimetic nanostructure of hydrothermally treated nano hydroxyapatite. In addition, the length of carbon nanotubes can be significantly increased under external magnetic fields when compared to nanotubes produced without a magnetic field. More importantly, the in vitro study demonstrated for the first time that osteoblast and mesenchymal stem cell adhesion and proliferation were greater on titanium with hydrothermally treated nanocrystalline hydroxyapatites/magnetically treated carbon nanotubes, which suggests

  18. Carbon Nanotubes for Space Applications

    NASA Technical Reports Server (NTRS)

    Meyyappan, Meyya

    2000-01-01

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

  19. Magnetic particle-based sandwich sensor with DNA-modified carbon nanotubes as recognition elements for detection of DNA hybridization.

    PubMed

    Hu, Po; Huang, Cheng Zhi; Li, Yuan Fang; Ling, Jian; Liu, Yu Ling; Fei, Liang Run; Xie, Jian Ping

    2008-03-01

    In this contribution, we design a visual sensor for DNA hybridization with DNA probe-modified magnetic particles (MPs) and multiwalled carbon nanotubes (MWNTs) without involving a visual recognition element such as fluorescent/chemiluminescent reagents. It was found that DNA probe-modified MWNTs, which could be dispersed in aqueous medium and have strong light scattering signals under the excitation of a light beam in the UV-vis region, could connect with DNA probe-modified MPs together in the presence of perfectly complementary target DNA and form a sandwich structure. In a magnetic field, the formed MP-MWNT species can easily be removed from the solution, resulting in a decrease of light scattering signals. Thus, a magnetic particle-based sandwich sensor could be developed to detect DNA hybridization by measuring the light scattering signals with DNA-modified MWNTs as recognition elements. Experiments showed that the DNA-modified MPs sensor could be reused at least 17 times and was stable for more than 6 months.

  20. Efficient and rapid uptake of magnetic carbon nanotubes into human monocytic cells: implications for cell-based cancer gene therapy.

    PubMed

    Gul-Uludag, Hilal; Lu, Weibing; Xu, Peng; Xing, James; Chen, Jie

    2012-05-01

    Monocyte-based gene therapies in cancer have been hampered by either the resistance of these cells to non-viral molecular delivery methods or their poor trafficking to the tumor site after their ex vivo manipulations. Magnetic nanoparticles (MNP)-loaded genetically engineered monocytes can efficiently delivered to tumor site by external magnetic field, but they are not ideal delivery tools due to their spherical shape. Hence, we have investigated the cellular uptake efficiency and cytotoxicity of fluorescein isothiocyanate (FITC)-labelled magnetic carbon nanotubes (FITC-mCNT) in human monocytic leukemia cell line THP-1 for application in cell-based gene therapy against cancer. Uptake of FITC-mCNT into THP-1 cells reached 100% only 1 h after the delivery. Confocal imaging confirmed that FITC-mCNT entered the cell cytoplasm and even into the nucleus. FITC-mCNT uptake did not compromise cell viability. This delivery system might therefore enhance cell-based cancer gene therapies.

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

    SciTech Connect

    Zhang, Yi; Qi, Shuhua; Zhang, Fan

    2012-11-15

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

  2. 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

  3. Carbon nanotube array actuators

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  4. Carbon nanotube biosensors

    PubMed Central

    Tîlmaciu, Carmen-Mihaela; Morris, May C.

    2015-01-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we describe their structural and physical properties, functionalization and cellular uptake, biocompatibility, and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers. PMID:26579509

  5. Carbon Nanotube Biosensors

    NASA Astrophysics Data System (ADS)

    Tilmaciu, Carmen-Mihaela; Morris, May

    2015-10-01

    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular Carbon Nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we will describe their structural and physical properties, discuss functionalization and cellular uptake, biocompatibility and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers.

  6. 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.

  7. Carbon nanotubes in hyperthermia therapy

    PubMed Central

    Singh, Ravi; Torti, Suzy V.

    2013-01-01

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

  8. Carbon nanotubes in hyperthermia therapy.

    PubMed

    Singh, Ravi; Torti, Suzy V

    2013-12-01

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

  9. Carbon nanotubes as vaccine scaffolds

    PubMed Central

    Scheinberg, David A.; McDevitt, Michael R.; Dao, Tao; Mulvey, Justin J.; Feinberg, Evan; Alidori, Simone

    2013-01-01

    Carbon nanotubes display characteristics that are potentially useful in their development as scaffolds for vaccine compositions. These features include stability in vivo, lack of intrinsic immunogenicity, low toxicity, and the ability to be appended with multiple copies of antigens. In addition, the particulate nature of carbon nanotubes and their unusual properties of rapid entry into antigen-presenting cells, such as dendritic cells, make them especially useful as carriers of antigens. Early attempts demonstrating carbon nanotube-based vaccines can be used in both infectious disease settings and cancer are promising. PMID:23899863

  10. Method for producing carbon nanotubes

    DOEpatents

    Phillips, Jonathan; Perry, William L.; Chen, Chun-Ku

    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.

  11. All About Chlorinated Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Erbahar, Dogan; Berber, Savas

    2011-03-01

    The halogens are viable alternatives to harsher chemicals in the post-process of purification of carbon nanotube production. However the chlorine is known to bind less agresively to carbon nanotubes than fluorine and hydrogen. Therefore, in principle the residual Cl left after the halogen gas treatment of the nanotubes can be removed without damaging the nanotube walls easier. We report ab initio density functional calculation results about pure and defective carbon nanotubes of various diameters interacting with single and multiple chlorine atoms. We first focus on pure nanotubes and investigate the adsorption of additional Cl atoms near the first adsorbtion site, investigate the clustering tendency and most favourable configurations. We report the energetics results as well as the alteration of electronic properties. We then focus on monovacancy and divacancy defects on carbon nanotubes. It is a known fact that the defective site to be more active in this case. We apply the same procedure as in the pure nanotubes but also investigate the effect of chlorination on reconstruction process and also electronic transport properties. Supported by TUBITAK Grant No 108T740.

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

    PubMed

    Ensafi, Ali A; Allafchian, Ali R

    2013-02-01

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

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

    PubMed

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

    2014-02-01

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

  14. 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.

  15. 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.

  16. Carbon nanotube optical mirrors

    NASA Astrophysics Data System (ADS)

    Chen, Peter C.; Rabin, Douglas

    2015-01-01

    We report the fabrication of imaging quality optical mirrors with smooth surfaces using carbon nanotubes (CNT) embedded in an epoxy matrix. CNT/epoxy is a multifunctional composite material that has sensing capabilities and can be made to incorporate self-actuation. Moreover, as the precursor is a low density liquid, large and lightweight mirrors can be fabricated by processes such as replication, spincasting, and three-dimensional printing. Therefore, the technology holds promise for the development of a new generation of lightweight, compact "smart" telescope mirrors with figure sensing and active or adaptive figure control. We report on measurements made of optical and mechanical characteristics, active optics experiments, and numerical modeling. We discuss possible paths for future development.

  17. 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.

  18. Carbon nanotube biconvex microcavities

    SciTech Connect

    Butt, Haider Ahmed, Rajib; Yetisen, Ali K.; Yun, Seok Hyun; Dai, Qing

    2015-03-23

    Developing highly efficient microcavities with predictive narrow-band resonance frequencies using the least amount of material will allow the applications in nonlinear photonic devices. We have developed a microcavity array that comprised multi-walled carbon nanotubes (MWCNT) organized in a biconvex pattern. The finite element model allowed designing microcavity arrays with predictive transmission properties and assessing the effects of the microarray geometry. The microcavity array demonstrated negative index and produced high Q factors. 2–3 μm tall MWCNTs were patterned as biconvex microcavities, which were separated by 10 μm in an array. The microcavity was iridescent and had optical control over the diffracted elliptical patterns with a far-field pattern, whose properties were predicted by the model. It is anticipated that the MWCNT biconvex microcavities will have implications for the development of highly efficient lenses, metamaterial antennas, and photonic circuits.

  19. Cantilevered carbon nanotube hygrometer

    NASA Astrophysics Data System (ADS)

    Kuroyanagi, Toshinori; Terada, Yuki; Takei, Kuniharu; Akita, Seiji; Arie, Takayuki

    2014-05-01

    We investigate the effects of humidity on the vibrations of carbon nanotubes (CNTs) using two types of CNT cantilevers: open-ended and close-ended CNT cantilevers. As the humidity increases, the resonant frequency of the open-ended CNT cantilever decreases due to the adsorption of water molecules onto the CNT tip, whereas that of the close-ended CNT cantilever increases probably due to the change in the viscosity of the air surrounding the CNT cantilever, which is negatively correlated with the humidity of air. Our findings suggest that a close-ended CNT cantilever is more suitable for a quick-response and ultrasensitive hygrometer because it continuously reads the viscosity change of moist air in the vicinity of the CNT.

  20. Carbon nanotube biconvex microcavities

    NASA Astrophysics Data System (ADS)

    Butt, Haider; Yetisen, Ali K.; Ahmed, Rajib; Yun, Seok Hyun; Dai, Qing

    2015-03-01

    Developing highly efficient microcavities with predictive narrow-band resonance frequencies using the least amount of material will allow the applications in nonlinear photonic devices. We have developed a microcavity array that comprised multi-walled carbon nanotubes (MWCNT) organized in a biconvex pattern. The finite element model allowed designing microcavity arrays with predictive transmission properties and assessing the effects of the microarray geometry. The microcavity array demonstrated negative index and produced high Q factors. 2-3 μm tall MWCNTs were patterned as biconvex microcavities, which were separated by 10 μm in an array. The microcavity was iridescent and had optical control over the diffracted elliptical patterns with a far-field pattern, whose properties were predicted by the model. It is anticipated that the MWCNT biconvex microcavities will have implications for the development of highly efficient lenses, metamaterial antennas, and photonic circuits.

  1. Oscillating carbon nanotori along carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hilder, Tamsyn A.; Hill, James M.

    2007-03-01

    The discovery of carbon nanostructures, such as nanotubes and C60 fullerenes, has given rise to a number of potential nanoscale devices. One such device is the gigahertz oscillator, comprising an inner shell sliding inside an outer shell of a multiwalled carbon nanotube, and which, at least theoretically, generates oscillatory frequencies in the gigahertz range. Following the concept of these gigahertz oscillators and the recent discovery of “fullerene crop circles,” here we propose the notion of a nanotorus-nanotube oscillator comprising a carbon nanotorus which is sucked by the van der Waals force onto the carbon nanotube, and subsequently oscillates along the nanotube axis due to the equal and opposite pulselike forces acting at either end of the nanotube. Assuming a continuum approach, where the interatomic interactions are replaced by uniform atomic surface densities, and assuming that the geometry of the nanotube and nanotorus is such that the nanotorus always remains symmetrically situated around the nanotube, we present the basic mechanics of such a system, including the determination of the suction and acceptance energies, and the frequency of the resulting oscillatory motion. In contrast to the previously studied gigahertz nanoscale oscillators, here the oscillatory frequencies are shown to be in the megahertz range. Our study, although purely theoretical must necessarily precede any experimental implementation of such oscillatory systems.

  2. PECVD Growth of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  3. Selective functionalization of carbon nanotubes

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

  4. Targeting carbon nanotubes against cancer.

    PubMed

    Fabbro, Chiara; Ali-Boucetta, Hanene; Da Ros, Tatiana; Kostarelos, Kostas; Bianco, Alberto; Prato, Maurizio

    2012-04-25

    The use of carbon nanotubes (CNTs) as polyvalent tools for cancer treatment is progressing at a very fast pace. The most promising approach is the targeted delivery of drugs, designed to selectively direct the therapeutic treatment towards the tumours. CNTs may offer several advantages to overcome one of the main limitations of most existing anticancer therapies, namely the lack of selectivity. Herein, an account of the existing literature on CNT-based nanomedicine for cancer treatment is given. The most significant results obtained so far in the field of drug delivery are presented for many anticancer chemotherapeutics (doxorubicin, methotrexate, taxanes, platinum analogues, camptothecine and gemcitabine), but also for immunotherapeutics and nucleic acids. Moreover, the alternative anticancer therapies based on thermal ablation and radiotherapy are discussed. The attention throughout the review is focused on the different targeting strategies proposed so far, mainly based on antibodies, but also on other specifically recognised molecules or on the application of an external magnetic field.

  5. 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 β-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 μmol 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.

  6. 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,

  7. Magnetic iron oxide nanoparticles functionalized multi-walled carbon nanotubes for toluene, ethylbenzene and xylene removal from aqueous solution.

    PubMed

    Yu, Fei; Ma, Jie; Wang, Juan; Zhang, Mingzheng; Zheng, Jie

    2016-03-01

    An effectively and functionally magnetic multi-walled carbon nanotube (MWCNTs) nano-composite (APCNT-KOH) was synthesized by a one-pot and facile method. The residual Fe catalyst particles of the as-prepared MWCNTs were utilized as magnetic materials through KOH activation. The resulting APCNT-KOH exhibited very high adsorption capacities for toluene (T), ethylbenzene (E), and xylene (X) (TEX) pollutants than many other adsorbents, because of their large specific surface area and high degree of surface activity. The adsorption process was found to be pH, ionic strength, and temperature dependent, and the maximum adsorption capacity was observed at pH 6 for TEX pollutants. The adsorption isotherm data were analyzed by applying the Langmuir, Freundlich, and Dubinin-Radushkevich isothermal models. The Langmuir model showed the best fit to the experimental isotherm data with a maximum adsorption capacity(qm,toluene = 63.34 mg/g, qm, ethylbenzene = 249.44 mg/g, qm,m-xylene = 227.05 mg/g, qm,o-xylene = 138.04 mg/g, qm,p-xylene = 105.59 mg/g). Adsorption kinetics of TEX on APCNT-KOH was appropriately described by the pseudo-second-order rate model. The desorption experiments revealed the typical adsorption-desorption hysteresis, indicating that the adsorption and desorption processes of TEX undergo different pathways due to porous structure changes before and after adsorption and desorption. Collective results demonstrate that the functionalized magnetic APCNT-KOH composites are highly-effective adsorbents for TEX removal, which provides a promising and green route for MWCNTs in wastewater treatment.

  8. Controlled growth of carbon nanotubes.

    PubMed

    Vajtai, R; Wei, B Q; Ajayan, P M

    2004-10-15

    Carbon nanotubes have extraordinary mechanical and electronic properties and hold great promise for future applications. The most important aspects of this structure are its low density, high aspect ratio, one dimensionality, high mechanical strength and high electrical and thermal conductivity. We present a short, state-of-the-art account of tailored nanotube growth. To provide these properties in real devices there exists a need for producing nanotubes on substrates. The challenge in the creation of mesoscale nanotube-based architectures and tailored nanotube networks consisting of thousands of tubes in a predefined order is obviously great. Currently, chemical vapour deposition (CVD) appears to be the most powerful method for achieving such required structures. We describe our work on a new synthesis method, based on catalytic CVD using mainly gas-phase catalyst delivery. Gas-phase catalyst delivery allows us to assemble single-walled and multi-walled carbon nanotubes in predetermined multiple orientations on substrates to build one- to three-dimensional architectures. We are able to control, to a large extent, the types of nanotubes produced, their lengths, locations and their orientations. The ability to make mesoscale architectures with nanotubes should lead us to develop applications in areas such as nano-electromechanical systems.

  9. Carbon nanotube computer.

    PubMed

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

    2013-09-26

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

  10. 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.

  11. Carbon Nanotubes for Polymer Photovoltaics

    NASA Astrophysics Data System (ADS)

    Anctil, Annick; Dileo, Roberta; Schauerman, Chris; Landi, Brian; Raffaelle, Ryne

    2007-03-01

    Carbon nanotubes are being investigated for optical absorption, exciton dissociation, and carrier transport in polymer photovoltaic devices. In the present work, single wall carbon nanotubes (SWNTs) were synthesized by an Alexandrite pulsed laser vaporization reactor at standard conditions and purified based upon our previously reported TOP procedure. The SWNTs were dispersed in polymer composites for pure MEH-PPV, pure P3HT, and [C60]-PCBM-P3HT (1:1 by weight) as a function of nanotube weight loading (0.1 -- 5% w/w). The AM0 current-voltage measurements for structures sandwiched between PEDOT/PSS coated ITO substrates and an evaporated aluminum contact demonstrate the dramatic effect of SWNT content on the short circuit current density, with conversions efficiencies consistently greater than 1%. The temperature coefficient for nanotube-containing polymer photovoltaics has been compared to conventional PCBM-P3HT devices, and the general relationship of increasing efficiency with increasing temperature is observed. However, the necessity to control nanotube percolation to prevent device shunting has led to recent developments which focus on controlling nanotube length through oxidative cutting, the deposition of intrinsic polymer layers, and the use of aligned carbon nanotube arrays for preferential charge transport.

  12. Characterization of magnetic soluble starch-functionalized carbon nanotubes and its application for the adsorption of the dyes.

    PubMed

    Chang, Peter R; Zheng, Pengwu; Liu, Baoxiang; Anderson, Debbie P; Yu, Jiugao; Ma, Xiaofei

    2011-02-28

    Soluble starch-functionalized multiwall carbon nanotube composites (MWCNT-starch) were prepared to improve the hydrophilicity and biocompatibility of MWCNTs. Characterization of the MWCNT-starch by Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM) and thermogravimetric analysis (TG), showed that the starch component (about 14.3 wt%) was covalently grafted onto the surface of MWCNT. MWCNT-starch-iron oxide composites, intended for use as adsorbents for the removal of dyes from aqueous solutions, were prepared by synthesizing iron oxide nanoparticles at the surface of MWCNT-starch. Starch acts as a template for growth of iron oxide nanoparticles which are uniformly dispersed on the surface of the MWCNT-starch. MWCNT-starch-iron oxide exhibits superparamagnetic properties with a saturation magnetization (23.15 emu/g) and better adsorption for anionic methyl orange (MO) and cationic methylene blue (MB) dyes than MWCNT-iron oxide.

  13. Properties of K,Rb-intercalated C{sub 60} encapsulated inside carbon nanotubes called peapods derived from nuclear magnetic resonance

    SciTech Connect

    Mahfouz, R.; Bouhrara, M.; Kim, Y.; Wågberg, T.; Goze-Bac, C.; Abou-Hamad, E.

    2015-09-21

    We present a detailed experimental study on how magnetic and electronic properties of Rb,K-intercalated C{sub 60} encapsulated inside carbon nanotubes called peapods can be derived from {sup 13}C nuclear magnetic resonance investigations. Ring currents do play a basic role in those systems; in particular, the inner cavities of nanotubes offer an ideal environment to investigate the magnetism at the nanoscale. We report the largest diamagnetic shifts down to −68.3 ppm ever observed in carbon allotropes, which is connected to the enhancement of the aromaticity of the nanotube envelope upon intercalation. The metallization of intercalated peapods is evidenced from the chemical shift anisotropy and spin-lattice relaxation (T{sub 1}) measurements. The observed relaxation curves signal a three-component model with two slow and one fast relaxing components. We assigned the fast component to the unpaired electrons charged C{sub 60} that show a phase transition near 100 K. The two slow components can be rationalized by the two types of charged C{sub 60} at two different positions with a linear regime following Korringa behavior, which is typical for metallic system and allow us to estimate the density of sate at Fermi level n(E{sub F})

  14. Studying single-wall carbon nanotubes through encapsulation: from optical methods till magnetic resonance.

    PubMed

    Simon, Ferenc

    2007-01-01

    Encapsulating fullerenes, magnetic fullerenes, 13C isotope enriched fullerenes, and organic solvents inside SWCNTs enables to yield unprecedented insight into their electronic, optical, and interfacial properties and to study SWCNT growth. In addition to customary methods of their studies such as e.g., optical absorption or Raman spectroscopy, these efforts enables to employ electron spin resonance (ESR) and nuclear magnetic resonance (NMR) spectroscopy. Encapsulated C60 fullerenes are transformed to inner tubes by a high temperature annealing. The diameter distribution of the inner tubes follow that of the outer ones and their unique, low defect concentration makes them an ideal model system for high resolution and energy dependent Raman studies. The observation of Raman modes of individual inner-outer tube pairs allows to measure the inner-outer tube interaction strength that is also well described theoretically. Reversible closing and opening of SWCNT can be studied in a diameter selective manner by encapsulating C60 and transforming it to an inner tube. The growth of inner tubes can be achieved from 13C enriched encapsulated organic solvents, which shows that the geometry of the fullerene does not play a particular role in the inner tube growth as it was originally thought. In addition, it opens new perspectives to explore the in-the-tube chemistry. Growth of inner tubes from 13C enriched fullerenes provides a unique isotope engineered heteronuclear system, where the outer tubes contain natural carbon and the inner walls are controllably 13C isotope enriched. The material enables to identify the vibrational modes of inner tubes which otherwise strongly overlap with the outer tube modes. The 13C NMR signal of the material has an unprecedented specificity for the small diameter SWCNTs. Temperature and field dependent 13C T1 studies show a uniform metallic-like electronic state for all inner tubes rather than distributed metallic and isolating behavior. A low

  15. 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

  16. Probing Photosensitization by Functionalized Carbon Nanotubes

    EPA Science Inventory

    Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that can damage organisms by biomembrane oxidation or mediate CNTs' environmental transformations. The photosensitized nature of derivatized carbon nanotubes from various synthetic methods, and thus ...

  17. Occupational Exposure to Carbon Nanotubes and Nanofibers

    MedlinePlus

    ... Current Intelligence Bulletin 65: Occupational Exposure to Carbon Nanotubes and Nanofibers Recommend on Facebook Tweet Share Compartir ... composed of engineered nanoparticles, such as metal oxides, nanotubes, nanowires, quantum dots, and carbon fullerenes (buckyballs), among ...

  18. Single carbon nanotube photovoltaic device

    NASA Astrophysics Data System (ADS)

    Barkelid, M.; Zwiller, V.

    2013-10-01

    Here we present photocurrent measurements on a single suspended carbon nanotube p-n junction. The p-n junction was induced by electrostatic doping by local gates, and the E11 and E22 resonances in the nanotube could be probed using photocurrent spectroscopy. Current-voltage characteristics were recorded, revealing an enhanced optoelectronic response on resonance. The internal power conversion efficiency for the nanotube diode was extracted on and off resonance with the E11 and E22, and a large internal power conversion efficiency was observed. An internal efficiency of up to 23% is reported for the E11, showing the potential of carbon nanotubes to be used as the active element in photovoltaic devices. Finally, a photovoltaic device is proposed which exploits this enhanced efficiency.

  19. Magnetically aligned iron oxide/gold nanoparticle-decorated carbon nanotube hybrid structure as a humidity sensor.

    PubMed

    Lee, Jaewook; Mulmi, Suresh; Thangadurai, Venkataraman; Park, Simon S

    2015-07-22

    Functionalized carbon nanotubes (f-CNTs), particularly CNTs decorated with nanoparticles (NPs), are of great interest because of their synergic effects, such as surface-enhanced Raman scattering, plasmonic resonance energy transfer, magnetoplasmonic, magnetoelectric, and magnetooptical effects. In general, research has focused on a single type of NP, such as a metal or metal oxide, that has been modified on a CNT surface. In this study, however, a new strategy is introduced for the decoration of two different NP types on CNTs. In order to improve the functionality of modified CNTs, we successfully prepared binary NP-decorated CNTs, namely, iron oxide/gold (Au) NP-decorated CNTs (IA-CNTs), which were created through two simple reactions in deionized water, without high temperature, high pressure, or harsh reducing agents. The physicochemical properties of IA-CNTs were characterized by ultraviolet/visible spectroscopy, Fourier transform infrared spectroscopy, a superconducting quantum interference device, scanning electron microscopy, and transmission electron microscopy. In this study, IA-CNTs were utilized to detect humidity. Magnetic IA-CNTs were aligned on interdigitated platinum electrodes under external magnetic fields to create a humidity-sensing channel, and its electrical conductivity was monitored. As the humidity increased, the electrical resistance of the sensor also increased. In comparison with various gases, for example, H2, O2, CO, CO2, SO2, and dry air, the IA-CNT-based humidity sensor exhibited high-selectivity performances. IA-CNTs also responded to heavy water (D2O), and it was established that the humidity detection mechanism had D2O-sensing capabilities. Further, the humidity from human out-breathing was also successfully detected by this system. In conclusion, these unique IA-CNTs exhibited potential application as gas detection materials.

  20. Magnetically aligned iron oxide/gold nanoparticle-decorated carbon nanotube hybrid structure as a humidity sensor.

    PubMed

    Lee, Jaewook; Mulmi, Suresh; Thangadurai, Venkataraman; Park, Simon S

    2015-07-22

    Functionalized carbon nanotubes (f-CNTs), particularly CNTs decorated with nanoparticles (NPs), are of great interest because of their synergic effects, such as surface-enhanced Raman scattering, plasmonic resonance energy transfer, magnetoplasmonic, magnetoelectric, and magnetooptical effects. In general, research has focused on a single type of NP, such as a metal or metal oxide, that has been modified on a CNT surface. In this study, however, a new strategy is introduced for the decoration of two different NP types on CNTs. In order to improve the functionality of modified CNTs, we successfully prepared binary NP-decorated CNTs, namely, iron oxide/gold (Au) NP-decorated CNTs (IA-CNTs), which were created through two simple reactions in deionized water, without high temperature, high pressure, or harsh reducing agents. The physicochemical properties of IA-CNTs were characterized by ultraviolet/visible spectroscopy, Fourier transform infrared spectroscopy, a superconducting quantum interference device, scanning electron microscopy, and transmission electron microscopy. In this study, IA-CNTs were utilized to detect humidity. Magnetic IA-CNTs were aligned on interdigitated platinum electrodes under external magnetic fields to create a humidity-sensing channel, and its electrical conductivity was monitored. As the humidity increased, the electrical resistance of the sensor also increased. In comparison with various gases, for example, H2, O2, CO, CO2, SO2, and dry air, the IA-CNT-based humidity sensor exhibited high-selectivity performances. IA-CNTs also responded to heavy water (D2O), and it was established that the humidity detection mechanism had D2O-sensing capabilities. Further, the humidity from human out-breathing was also successfully detected by this system. In conclusion, these unique IA-CNTs exhibited potential application as gas detection materials. PMID:26112318

  1. Carbon Nanotube Based Molecular Electronics

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1998-01-01

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

  2. 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.

  3. In situ immobilization of a general resolving agent on the magnetic multi-wall carbon nanotube for the direct enantioenrichment of DL-mandelic acid.

    PubMed

    Tarigh, Ghazale Daneshvar; Shemirani, Farzaneh

    2015-11-01

    L-Threonine (L-thr) as a general chiral selector anchored on the surface of magnetic multi-wall carbon nanotube (MMWCNT) was prepared using an in situ electrostatic adsorption and studied as a new magnetically chiral selector for the separation of chiral DL-mandelic acid (DL-MA) as a model sample. By varying the pH, DL-MA was adsorbed on the surface of magnetic chiral selector through hydrogen bonds. It is recognized that MMWCNT with chiral ligands on its surface simultaneously possesses both magnetic property and direct chiral recognition ability. The successful immobilization of L-thr onto the surface of MMWCNT was confirmed by infrared spectra (FT-IR), X-ray diffraction patterns (XRD) and transmission electron microscopy (TEM). The FT-IR and mass spectra of supernatant and elution solutions also confirmed the immobilization of L-thr onto the surface of MMWCNT. The analysis results of specific rotation, HPLC and ultraviolet-visible spectroscopy reveal that the L-thr-MMWCNT show stronger complexation of (+)-enantiomer than (-)-enantiomer. The functional magnetic nanotubes were easily separated from the racemic solution using an external magnetic field which demonstrated its feasibility of recycling the adsorbent. All processes including in situ immobilization, enantioseparation (enantioenrichment) and magnetic separation were done by single process in a short time (only 10min).

  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

  5. 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 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

  6. Large-Scale Processing of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Finn, John; Sridhar, K. R.; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    1998-01-01

    Scale-up difficulties and high energy costs are two of the more important factors that limit the availability of various types of nanotube carbon. While several approaches are known for producing nanotube carbon, the high-powered reactors typically produce nanotubes at rates measured in only grams per hour and operate at temperatures in excess of 1000 C. These scale-up and energy challenges must be overcome before nanotube carbon can become practical for high-consumption structural and mechanical applications. This presentation examines the issues associated with using various nanotube production methods at larger scales, and discusses research being performed at NASA Ames Research Center on carbon nanotube reactor technology.

  7. Microscopy of single-layer carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Su; Zhou, Dan

    1994-07-01

    Single-layer carbon nanotubes produced with yttrium carbide as catalyst have been studied with high-resolution transmission electron microscopy (HRTEM). The morphology, condition of iamging and the method of measurement to determine the actual diameter of a single-layer carbon nanotube have been detailed and the growth mechanism of single-layer carbon nanotubes has been discussed in this research.

  8. 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.

  9. 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

  10. 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.

  11. Purification of Carbon Nanotubes by Proton Irradiation

    NASA Astrophysics Data System (ADS)

    Kim, Euikwoun; Lee, Jeonggil; Lee, Younman; Jeon, Jaekyun; Kim, Jae-Yong; Kim, Jeongha; Shin, Kwanwoo; Youn, Sang-Pil; Kim, Kyeryung

    2007-10-01

    Carbon nanotubes (CNTs) exhibit variety of superior physical properties including well-defined nanodimensional structure, high electrical and thermal conductivity, and good mechanical stability against external irradiations. Further, a large specific surface area per unit weight suggests that carbon nanotubes could be excellent candidates for gas storage, purification, and separation. However, the practical application of CNTs is limited mainly due to the metallic impurities that were used as a catalyst during the fabrication process. Here, we irradiated CNTs by using high energy proton beams (35.7 MeV at the Bragg Peak). Interestingly, metallic impurities such as Fe, Ni, Co and chunk of amorphous carbon that were attached on the surface of CNTs were completely removed after the irradiation. The mechanism of such the purification process is not understood. The possible speculation will be demonstrated combined with the changes of physical properties including the appearance of the magnetism after the irradiation.

  12. Carbon nanotube-polymer composite actuators

    DOEpatents

    Gennett, Thomas; Raffaelle, Ryne P.; Landi, Brian J.; Heben, Michael J.

    2008-04-22

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

  13. Carbon nanotube: the inside story.

    PubMed

    Ando, Yoshinori

    2010-06-01

    Carbon nanotubes (CNTs) were serendipitously discovered as a byproduct of fullerenes by direct current (DC) arc discharge; and today this is the most-wanted material in the nanotechnology research. In this brief review, I begin with the history of the discovery of CNTs and focus on CNTs produced by arc discharge in hydrogen atmosphere, which is little explored outside my laboratory. DC arc discharge evaporation of pure graphite rod in pure hydrogen gas results in multi-walled carbon nanotubes (MWCNTs) of high crystallinity in the cathode deposit. As-grown MWCNTs have very narrow inner diameter. Raman spectra of these MWCNTs show high-intensity G-band, unusual high-frequency radial breathing mode at 570 cm(-1), and a new characteristic peak near 1850 cm(-1). Exciting carbon nanowires (CNWs), consisting of a linear carbon chain in the center of MWCNTs are also produced. Arc evaporation of graphite rod containing metal catalysts results in single-wall carbon nanotubes (SWCNTs) in the whole chamber like macroscopic webs. Two kinds of arc method have been developed to produce SWCNTs: Arc plasma jet (APJ) and Ferrum-Hydrogen (FH) arc methods. Some new purification methods for as-produced SWCNTs are reviewed. Finally, double-walled carbon nanotubes (DWCNTs) are also described.

  14. Gears Based on Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Jaffe, Richard; Han, Jie; Globus, Al; Deardorff, Glenn

    2005-01-01

    Gears based on carbon nanotubes (see figure) have been proposed as components of an emerging generation of molecular- scale machines and sensors. In comparison with previously proposed nanogears based on diamondoid and fullerene molecules, the nanotube-based gears would have simpler structures and are more likely to be realizable by practical fabrication processes. The impetus for the practical development of carbon-nanotube- based gears arises, in part, from rapid recent progress in the fabrication of carbon nanotubes with prescribed diameters, lengths, chiralities, and numbers of concentric shells. The shafts of the proposed gears would be made from multiwalled carbon nanotubes. The gear teeth would be rigid molecules (typically, benzyne molecules), bonded to the nanotube shafts at atomically precise positions. For fabrication, it may be possible to position the molecular teeth by use of scanning tunneling microscopy (STM) or other related techniques. The capability to position individual organic molecules at room temperature by use of an STM tip has already been demonstrated. Routes to the chemical synthesis of carbon-nanotube-based gears are also under investigation. Chemical and physical aspects of the synthesis of molecular scale gears based on carbon nanotubes and related molecules, and dynamical properties of nanotube- based gears, have been investigated by computational simulations using established methods of quantum chemistry and molecular dynamics. Several particularly interesting and useful conclusions have been drawn from the dynamical simulations performed thus far: The forces acting on the gears would be more sensitive to local molecular motions than to gross mechanical motions of the overall gears. Although no breakage of teeth or of chemical bonds is expected at temperatures up to at least 3,000 K, the gears would not work well at temperatures above a critical range from about 600 to about 1,000 K. Gear temperature could probably be controlled by

  15. CMOS Integrated Carbon Nanotube Sensor

    SciTech Connect

    Perez, M. S.; Lerner, B.; Boselli, A.; Lamagna, A.; Obregon, P. D. Pareja; Julian, P. M.; Mandolesi, P. S.; Buffa, F. A.

    2009-05-23

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

  16. Photodetector based on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Pavlov, A.; Kitsyuk, E.; Ryazanov, R.; Timoshenkov, V.; Adamov, Y.

    2015-09-01

    Photodetector based on carbon nanotubes (CNT) was investigated. Sensors were done on quartz and silicon susbtrate. Samples of photodetectors sensors were produced by planar technology. This technology included deposition of first metal layer (Al), lithography for pads formation, etching, and formation of local catalyst area by inverse lithography. Vertically-aligned multi-wall carbon nanotubes were directly synthesized on substrate by PECVD method. I-V analysis and spectrum sensitivity of photodetector were investigated for 0.4 μm - 1.2 μm wavelength. Resistivity of CNT layers over temperature was detected in the range of -20°C to 100°C.

  17. 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 6.0-100μmolL(-1) with a detection limit of 0.02μmolL(-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.

  18. All carbon nanotubes are not created equal

    SciTech Connect

    Geohegan, David B; Puretzky, Alexander A; Rouleau, Christopher M

    2010-01-01

    This chapter presents the various factors that enter into consideration when choosing the source of carbon nanotubes for a specific application. Carbon nanotubes are giant molecules made of pure carbon. They have captured the imagination of the scientific community by the unique structure that provides superior physical, chemical, and electrical properties. However, a surprisingly wide disparity exists between the intrinsic properties determined under ideal conditions and the properties that carbon nanotubes exhibit in real world situations. The lack of uniformity in carbon nanotube properties is likely to be the main obstacle holding back the development of carbon nanotube applications. This tutorial addresses the nonuniformity of carbon nanotube properties from the synthesis standpoint. This synthesis-related nonuniformity is on top of the intrinsic chirality distribution that gives the ~1:2 ratio of metallic to semiconducting nanotubes. From the standpoint of carbon bonding chemistry the variation in the quality and reproducibility of carbon nanotube materials is not unexpected. It is an intrinsic feature that is related to the metastability of carbon structures. The extent to which this effect is manifested in carbon nanotube formation is governed by the type and the kinetics of the carbon nanotube synthesis reaction. Addressing this variation is critical if nanotubes are to live up to the potential already demonstrated by their phenomenal physical properties.

  19. Biomedical applications of carbon-nanotube composites.

    PubMed

    Meredith, Jay Russell; Jin, Chunming; Narayan, Roger J; Aggarwal, Ravi

    2013-01-01

    The unique physical, chemical and mechanical properties of carbon nanotubes make them attractive for a variety of biomedical applications. Carbon nanotubes have been used to modify conventional biomedical materials to enhance mechanical properties, biocompatibility, or to impart other functionalities. New multifunctional composite materials using carbon nanotubes have been developed by combining them with inorganic, polymeric or biological materials. The biomedical applications for which novel carbon nanotube composites have been investigated include antimicrobial coatings, neural implants, tissue engineering scaffolds and electrochemical biosensors. In this paper, research on development and application of carbon nanotube composites for biomedical applications has been reviewed. PMID:23277017

  20. Synthesis of carbon nanotubes and nanotube forests on copper catalyst

    NASA Astrophysics Data System (ADS)

    Kruszka, Bartosz; Terzyk, Artur P.; Wiśniewski, Marek; Gauden, Piotr A.; Szybowicz, Mirosław

    2014-09-01

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

  1. Modified carbon nanotubes and methods of forming carbon nanotubes

    DOEpatents

    Heintz, Amy M.; Risser, Steven; Elhard, Joel D.; Moore, Bryon P.; Liu, Tao; Vijayendran, Bhima R.

    2016-06-14

    In this invention, processes which can be used to achieve stable doped carbon nanotubes are disclosed. Preferred CNT structures and morphologies for achieving maximum doping effects are also described. Dopant formulations and methods for achieving doping of a broad distribution of tube types are also described.

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

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

    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.

  3. 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.

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

    PubMed

    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.

  5. 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.

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

    PubMed

    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. PMID:25725890

  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. 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.

  9. Plasma CVD of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  10. Conductance Oscillations in Squashed Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  11. Supported lipid bilayer/carbon nanotube hybrids

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

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

  12. Simultaneous determination of phenolic compounds in sesame oil using LC-MS/MS combined with magnetic carboxylated multi-walled carbon nanotubes.

    PubMed

    Wu, Rao; Ma, Fei; Zhang, Liangxiao; Li, Peiwu; Li, Guangming; Zhang, Qi; Zhang, Wen; Wang, Xiuping

    2016-08-01

    A novel magnetic carboxylated multi-walled carbon nanotubes (c-MWCNT-MNPs) was proposed for magnetic solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry to determine phenolic compounds in sesame oil. In this study, c-MWCNT-MNPs were acquired by simply dispersing Fe3O4 magnetic nanoparticles into carboxylated multi-walled carbon nanotubes. The major parameters affecting extraction efficiency were optimized, including the type and volume of desorption solvents, extraction and desorption time, washing solution, and sorbent amount. The limit of quantifications and limit of detections were from 0.03μg/kg to 43.00μg/kg and from 0.01μg/kg to 13.60μg/kg, respectively. The recoveries of phenolic compounds in vegetable oils were in the range of 83.8-125.9% with inter-day and intra-day precisions of less than 13.2%. It was confirmed that this method was simple, rapid and reliable with an excellent potential for routine analysis of phenolic compounds in oil samples. PMID:26988510

  13. Conductance of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Datta, Supriyo; Anatram, M. P.

    1998-01-01

    The recent report of quantized conductance in a 4 m long multiwalled nanotube (MWNT) raises the exciting possibility of ballistic transport at room temperature over relatively long distances. We argue that this is made possible by the special symmetry of the eigenstates of the lowest propagating modes in metallic nanotubes which suppresses backscattering. This unusual effect is absent for the higher propagating modes so that transport is not ballistic once the bias exceeds the cut-off energy for the higher modes, which is estimated to be approximately 75 meV for nanotubes of diameter approximately 15 nm. Also, we show that the symmetry of the eigenstates can significantly affect their coupling to the reservoir and hence the contact resistance. A simple model is presented that can be used to understand the observed conductance-voltage characteristics.

  14. Can nitrones functionalize carbon nanotubes?

    PubMed

    Ghini, Giacomo; Luconi, Lapo; Rossin, Andrea; Bianchini, Claudio; Giambastiani, Giuliano; Cicchi, Stefano; Lascialfari, Luisa; Brandi, Alberto; Giannasi, Alessandra

    2010-01-14

    An unprecedented functionalization of multi-walled carbon nanotubes (MWCNTs) has been conveniently achieved by the 1,3-dipolar cycloaddition of a cyclic nitrone. This organic functionalization yields materials with a great solubility in DMF (close to 10 mg per mL of DMF) preferentially occurring at the defects of the MWCNT sp(2) network. PMID:20024342

  15. Terahertz detection and carbon nanotubes

    SciTech Connect

    Leonard, Francois

    2014-06-11

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

  16. Thermoelectrics: Carbon nanotubes get high

    NASA Astrophysics Data System (ADS)

    Crispin, Xavier

    2016-04-01

    Waste heat can be converted to electricity by thermoelectric generators, but their development is hindered by the lack of cheap materials with good thermoelectric properties. Now, carbon-nanotube-based materials are shown to have improved properties when purified to contain only semiconducting species and then doped.

  17. Terahertz detection and carbon nanotubes

    ScienceCinema

    Leonard, Francois

    2016-07-12

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

  18. 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.

  19. 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.

  20. Endohedral impurities in carbon nanotubes.

    PubMed

    Clougherty, Dennis P

    2003-01-24

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value. The effective potential is found to have O(2) symmetry, in agreement with numerical calculations. For metallic zigzag nanotubes endohedrally doped with transition metals in the dilute limit, the low-energy properties of the system may display two-channel Kondo behavior; however, strong vibronic coupling is seen to exponentially suppress the Kondo energy scale. PMID:12570507

  1. Endohedral Impurities in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis P.

    2003-01-01

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value. The effective potential is found to have O(2) symmetry, in agreement with numerical calculations. For metallic zigzag nanotubes endohedrally doped with transition metals in the dilute limit, the low-energy properties of the system may display two-channel Kondo behavior; however, strong vibronic coupling is seen to exponentially suppress the Kondo energy scale.

  2. 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.

  3. Pulsed laser deposition of carbon nanotube and polystyrene-carbon nanotube composite thin films

    NASA Astrophysics Data System (ADS)

    Stramel, A. A.; Gupta, M. C.; Lee, H. R.; Yu, J.; Edwards, W. C.

    2010-12-01

    In this work, we report on the fabrication of carbon nanotube thin films via pulsed laser deposition using a pulsed, diode pumped, Tm:Ho:LuLF laser with 2 μm wavelength. The thin films were deposited on silicon substrates using pure carbon nanotube targets and polystyrene-carbon nanotube composite targets. Raman spectra, scanning electron micrographs, and transmission electron micrographs show that carbon nanotubes are present in the deposited thin films, and that the pulsed laser deposition process causes minimal degradation to the quality of the nanotubes when using pure carbon nanotube targets.

  4. 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

  5. Bloch oscillations in carbon nanotubes.

    PubMed

    Jódar, Esther; Pérez-Garrido, Antonio; Rojas, Fernando

    2009-05-27

    Bloch oscillations arise when electrons are in a one-dimensional linear chain of atoms under a constant electric field. In this paper we show numerically that electrons in different types of carbon nanotubes show oscillations with a Bloch frequency proportional to the constant electric field applied along the nanotube axis. We show these oscillations, calculating the quadratic displacement as a function of the electric field. Because of the double periodicity of the nanotubes' geometry (the lattice constant and the lines of atoms) two frequencies appear, one twice the value of the other. These frequencies coincide perfectly with those predicted for a linear chain of atoms, taking into account the periodicity considered in each case.

  6. Quantum transport in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Laird, Edward A.; Kuemmeth, Ferdinand; Steele, Gary A.; Grove-Rasmussen, Kasper; Nygârd, Jesper; Flensberg, Karsten; Kouwenhoven, Leo P.

    2015-07-01

    Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries have uncovered new phenomena that completely change our understanding of transport in these devices, especially the role of the spin and valley degrees of freedom. This review describes the modern understanding of transport through nanotube devices. Unlike in conventional semiconductors, electrons in nanotubes have two angular momentum quantum numbers, arising from spin and valley freedom. The interplay between the two is the focus of this review. The energy levels associated with each degree of freedom, and the spin-orbit coupling between them, are explained, together with their consequences for transport measurements through nanotube quantum dots. In double quantum dots, the combination of quantum numbers modifies the selection rules of Pauli blockade. This can be exploited to read out spin and valley qubits and to measure the decay of these states through coupling to nuclear spins and phonons. A second unique property of carbon nanotubes is that the combination of valley freedom and electron-electron interactions in one dimension strongly modifies their transport behavior. Interaction between electrons inside and outside a quantum dot is manifested in SU(4) Kondo behavior and level renormalization. Interaction within a dot leads to Wigner molecules and more complex correlated states. This review takes an experimental perspective informed by recent advances in theory. As well as the well-understood overall picture, open questions for the field are also clearly stated. These advances position nanotubes as a leading system for the study of spin and valley physics in one dimension where electronic disorder and hyperfine interaction can both be reduced to a low level.

  7. Rapid determination of trans-resveratrol in vegetable oils using magnetic hydrophilic multi-walled carbon nanotubes as adsorbents followed by liquid chromatography-tandem mass spectrometry.

    PubMed

    Ma, Fei; Li, Peiwu; Zhang, Qi; Yu, Li; Zhang, Liangxiao

    2015-07-01

    In the present work, a rapid and simple procedure was developed and validated for the analysis of trans-resveratrol in vegetable oils based on magnetic hydrophilic multi-walled carbon nanotubes (h-MWCNT-MNPs) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). h-MWCNT-MNPs were simply obtained by wrapping amine-functionalized Fe3O4 magnetic nanoparticles into previously oxidized hydrophilic multi-walled carbon nanotubes. The major parameters affecting extraction efficiency were investigated, including the type and volume of desorption solvents, extraction and desorption time, washing solution, and sorbent amount. The limit of detection (LOD) and the limit of quantification (LOQ) were calculated as 0.6 and 2.0 μg/kg, respectively. The recoveries of trans-resveratrol in oil samples were in the range of 90.0-110.0% with RSDs of less than 17.5%. The results showed that only peanut oil contained trans-resveratrol, ranging from 8 ± 1 to 103 ± 12 μg/kg. The proposed method is reliable and robust, having an excellent potential for the analysis of trans-resveratrol in edible oils.

  8. 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 μg/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 μg/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.

  9. Carbon nanotube coatings as chemical absorbers

    DOEpatents

    Tillotson, Thomas M.; Andresen, Brian D.; Alcaraz, Armando

    2004-06-15

    Airborne or aqueous organic compound collection using carbon nanotubes. Exposure of carbon nanotube-coated disks to controlled atmospheres of chemical warefare (CW)-related compounds provide superior extraction and retention efficiencies compared to commercially available airborne organic compound collectors. For example, the carbon nanotube-coated collectors were four (4) times more efficient toward concentrating dimethylmethyl-phosphonate (DMMP), a CW surrogate, than Carboxen, the optimized carbonized polymer for CW-related vapor collections. In addition to DMMP, the carbon nanotube-coated material possesses high collection efficiencies for the CW-related compounds diisopropylaminoethanol (DIEA), and diisopropylmethylphosphonate (DIMP).

  10. Local gate control in carbon nanotube quantum devices

    NASA Astrophysics Data System (ADS)

    Biercuk, Michael Jordan

    This thesis presents transport measurements of carbon nanotube electronic devices operated in the quantum regime. Nanotubes are contacted by source and drain electrodes, and multiple lithographically-patterned electrostatic gates are aligned to each device. Transport measurements of device conductance or current as a function of local gate voltages reveal that local gates couple primarily to the proximal section of the nanotube, hence providing spatially localized control over carrier density along the nanotube length. Further, using several different techniques we are able to produce local depletion regions along the length of a tube. This phenomenon is explored in detail for different contact metals to the nanotube. We utilize local gating techniques to study multiple quantum dots in carbon nanotubes produced both by naturally occurring defects, and by the controlled application of voltages to depletion gates. We study double quantum dots in detail, where transport measurements reveal honeycomb charge stability diagrams. We extract values of energy-level spacings, capacitances, and interaction energies for this system, and demonstrate independent control over all relevant tunneling rates. We report rf-reflectometry measurements of gate-defined carbon nanotube quantum dots with integrated charge sensors. Aluminum rf-SETs are electrostatically coupled to carbon nanotube devices and detect single electron charging phenomena in the Coulomb blockade regime. Simultaneous correlated measurements of single electron charging are made using reflected rf power from the nanotube itself and from the rf-SET on microsecond time scales. We map charge stability diagrams for the nanotube quantum dot via charge sensing, observing Coulomb charging diamonds beyond the first order. Conductance measurements of carbon nanotubes containing gated local depletion regions exhibit plateaus as a function of gate voltage, spaced by approximately 1e2/h, the quantum of conductance for a single

  11. 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)

  12. 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.

  13. Magnetic dummy molecularly imprinted polymers based on multi-walled carbon nanotubes for rapid selective solid-phase extraction of 4-nonylphenol in aqueous samples.

    PubMed

    Rao, Wei; Cai, Rong; Yin, Yuli; Long, Fang; Zhang, Zhaohui

    2014-10-01

    In this paper, a highly selective sample clean-up procedure combining magnetic dummy molecular imprinting with solid-phase extraction was developed for rapid separation and determination of 4-nonylphenol (NP) in the environmental water samples. The magnetic dummy molecularly imprinted polymers (mag-DMIPs) based on multi-walled carbon nanotubes were successfully synthesized with a surface molecular imprinting technique using 4-tert-octylphenol as the dummy template and tetraethylorthosilicate as the cross-linker. The maximum adsorption capacity of the mag-DMIPs for NP was 52.4 mg g(-1) and it took about 20 min to achieve the adsorption equilibrium. The mag-DMIPs exhibited the specific selective adsorption toward NP. Coupled with high performance liquid chromatography analysis, the mag-DMIPs were used to extract solid-phase and detect NP in real water samples successfully with the recoveries of 88.6-98.1%.

  14. Dispersion of carbon nanotubes using organic solvents.

    PubMed

    Dumonteil, S; Demortier, A; Detriche, S; Raes, C; Fonseca, A; Rühle, M; Nagy, J B

    2006-05-01

    Phenyl ethyl alcohol was used for fast and stable dispersion of carbon nanotubes. This solvent, more effective than ethanol and toluene, allows easy dispersion of carbon nanotubes for TEM characterization. For TEM grids prepared at high dilution, it is possible to observe each tube separately. Applying that solvent, it was possible to measure the length, the diameter and the solubility of different carbon nanotubes samples.

  15. Method of making carbon nanotube composite materials

    DOEpatents

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

    2014-05-20

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

  16. A Novel Nanofilm Sensor Based on Poly-(Alizarin Red)/Fe3O4 Magnetic Nanoparticles-Multiwalled Carbon Nanotubes Composite Material for Determination of Nitrite.

    PubMed

    Qu, Jianying; Dong, Ying; Yong, Wang; Lou, Tongfang; Du, Xueping; Qu, Jianhang

    2016-03-01

    Fe3O4 magnetic nanoparticles were synthesized by chemical co-precipitation with sodium citrate as surfactant and were characterized by FT-IR spectrometer, X-ray diffraction and transmission electron microscopy. A novel nitrite sensor was fabricated by electropolymerization of alizarin red on the surface of glassy carbon electrode modified with Fe3O4-multiwalled carbon nanotubes composite nanofilm. Under the optimal experimental conditions, it was showed that the proposed sensor exhibited good electrocatalytic activity to the oxidation of nitrite, and the peak current increased linearly with the nitrite concentration from 9.64 x 10(-6) mol x L(-1) to 1.30 x 10(-3) mol x L(-1) (R = 0.9976) with a detection limit of 1.19 x 10(-6) mol x L(-1) (S/N = 3). This sensor showed excellent sensitivity, wide linear range, stability and repeatability for nitrite determination with potential applications.

  17. 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.

  18. 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.

  19. Ballistic Fracturing of Carbon Nanotubes.

    PubMed

    Ozden, Sehmus; Machado, Leonardo D; Tiwary, ChandraSekhar; Autreto, Pedro A S; Vajtai, Robert; Barrera, Enrique V; Galvao, Douglas S; Ajayan, Pulickel M

    2016-09-21

    Advanced materials with multifunctional capabilities and high resistance to hypervelocity impact are of great interest to the designers of aerospace structures. Carbon nanotubes (CNTs) with their lightweight and high strength properties are alternative to metals and/or metallic alloys conventionally used in aerospace applications. Here we report a detailed study on the ballistic fracturing of CNTs for different velocity ranges. Our results show that the highly energetic impacts cause bond breakage and carbon atom rehybridizations, and sometimes extensive structural reconstructions were also observed. Experimental observations show the formation of nanoribbons, nanodiamonds, and covalently interconnected nanostructures, depending on impact conditions. Fully atomistic reactive molecular dynamics simulations were also carried out in order to gain further insights into the mechanism behind the transformation of CNTs. The simulations show that the velocity and relative orientation of the multiple colliding nanotubes are critical to determine the impact outcome. PMID:27564421

  20. Ballistic Fracturing of Carbon Nanotubes.

    PubMed

    Ozden, Sehmus; Machado, Leonardo D; Tiwary, ChandraSekhar; Autreto, Pedro A S; Vajtai, Robert; Barrera, Enrique V; Galvao, Douglas S; Ajayan, Pulickel M

    2016-09-21

    Advanced materials with multifunctional capabilities and high resistance to hypervelocity impact are of great interest to the designers of aerospace structures. Carbon nanotubes (CNTs) with their lightweight and high strength properties are alternative to metals and/or metallic alloys conventionally used in aerospace applications. Here we report a detailed study on the ballistic fracturing of CNTs for different velocity ranges. Our results show that the highly energetic impacts cause bond breakage and carbon atom rehybridizations, and sometimes extensive structural reconstructions were also observed. Experimental observations show the formation of nanoribbons, nanodiamonds, and covalently interconnected nanostructures, depending on impact conditions. Fully atomistic reactive molecular dynamics simulations were also carried out in order to gain further insights into the mechanism behind the transformation of CNTs. The simulations show that the velocity and relative orientation of the multiple colliding nanotubes are critical to determine the impact outcome.

  1. Carbon Nanotubes: Molecular Electronic Components

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1997-01-01

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

  2. From carbon nanobells to nickel nanotubes

    NASA Astrophysics Data System (ADS)

    Ma, S.; Srikanth, V. V. S. S.; Maik, D.; Zhang, G. Y.; Staedler, T.; Jiang, X.

    2009-01-01

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

  3. From carbon nanobells to nickel nanotubes

    SciTech Connect

    Ma, S.; Srikanth, V. V. S. S.; Maik, D.; Zhang, G. Y.; Staedler, T.; Jiang, X.

    2009-01-05

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

  4. Synthesis of magnetic oxidized multiwalled carbon nanotube-κ-carrageenan-Fe3O4 nanocomposite adsorbent and its application in cationic Methylene Blue dye adsorption.

    PubMed

    Duman, Osman; Tunç, Sibel; Polat, Tülin Gürkan; Bozoğlan, Bahar Kancı

    2016-08-20

    In this study, magnetic oxidized multiwalled carbon nanotube (OMWCNT)-Fe3O4 and OMWCNT-κ-carrageenan-Fe3O4 nanocomposites were synthesized and used as adsorbent for the removal of Methylene Blue (MB) from aqueous solution. Magnetic nanocomposites were characterized by using of specific surface area, Fourier transform infrared, X-ray diffraction, vibrating sample magnetometry, thermal gravimetric analysis, scanning electron microscope and transmission electron microscope measurements. The results of characterization analyses exhibited that OMWCNT was successfully modified with κ-carrageenan. Furthermore, OMWCNT-Fe3O4 and OMWCNT-κ-carrageenan-Fe3O4 nanocomposites were of a super-paramagnetic property. Adsorption studies revealed that the data of adsorption kinetics and isotherm were well fitted by the pseudo second-order kinetic model and Langmuir isotherm model, respectively. The adsorption amounts of magnetic adsorbents increased with contact time and initial dye concentration. Compared with magnetic OMWCNT-Fe3O4 nanocomposite, magnetic OMWCNT-κ-carrageenan-Fe3O4 nanocomposite showed a better adsorption performance for the removal of MB from aqueous solution. Therefore, OMWCNT-κ-carrageenan-Fe3O4 nanocomposite may be used as a magnetic adsorbent to remove the cationic dyes from wastewaters.

  5. γ-Fe2O3 magnetic nanoparticle functionalized with carboxylated multi walled carbon nanotube: Synthesis, characterization, analytical and biomedical application

    NASA Astrophysics Data System (ADS)

    Kılınç, Ersin

    2016-03-01

    In recent years, magnetic nanoparticles attained special interest in nanobiotechnology and nanomedicine due to their uniqe properties and biocompatibilities. From this perspective, hybride nanostructure composed from γ-Fe2O3 magnetic nanoparticle and carboxylated multi walled carbon nanotube was synthesized and characterized by FT-IR, VSM, SEM, HR-TEM and ICP-OES. Microscopy images showed that magnetic nanoparticles were nearly spherical structure that arranged on the axis of carboxylated MWCNT. Particle size was found lower than 10 nm. VSM results showed that the obtained magnetic nanoparticles presented superparamagnetic properties at room temperature. The magnetic saturation value was determined as 35.2 emu/g. It was used for the adsorption and controlled release of harmane, a potent tremor-producing neurotoxin. Maximum adsorption capacity was calculated as 151.5 mg/g from Langmuir isotherm. Concentration of harmane was determined by HPLC with fluorescence detection. The antimicrobial activity of synthesized magnetic nanoparticle was investigated against gram-negative and gram-positive bacteria. However, no activity was observed.

  6. LDRD final report on carbon nanotube composites

    SciTech Connect

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

    1997-04-01

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

  7. Engineering carbon nanotubes and nanotube circuits using electrical breakdown.

    PubMed

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

    2001-04-27

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

  8. Improved Process for Fabricating Carbon Nanotube Probes

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  9. Carbon Nanotube Superconducting Quantum Interference Device.

    NASA Astrophysics Data System (ADS)

    Bouchiat, Vincent; Cleuziou, Jean-Pierre; Ondarcuhu, Thierry; Monthioux, Marc; Wernsdorfer, Wolfgang

    2007-03-01

    We report on the study of a superconducting quantum interference device (SQUID) with Josephson junctions made of portions of metallic single-walled carbon nanotube [1]. Quantum confinement in each nanotube junction induces a discrete quantum dot (QD) energy level structure, which can be controlled with a lateral electrostatic gate. In addition, a backgate electrode can vary the transparency of the QD barriers, thus permitting to change the hybridization of the QD states with the superconducting contacts [2]. The gates are also used to directly tune the quantum phase interference of the Cooper pairs circulating in the SQUID ring. Optimal modulation of a 6nA supercurrent current with magnetic flux is achieved when both QD junctions are in the ``on'' or ``off'' state. Futhermore, the SQUID design establishes that these CNT Josephson junctions can be used as gate-controlled π-junctions. This allow to verify that the sign of the current-phase relation across a proximity coupled Qdot can be reversed with a gate voltage. Noise studies shows that the noise figure of the nanotube SQUID together with the size of the junction should allow the detection of a single molecule magnet. [1] J-P. Cleuziou et al. Nature Nanotec., 1, 53, (2006). [2] J-P. Cleuziou et al. cond-mat/0610622.

  10. Characterization of carbon nanotubes decorated with NiFe2O4 magnetic nanoparticles as a novel electrochemical sensor: application for highly selective determination of sotalol using voltammetry.

    PubMed

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

    2013-01-01

    A magnetic nano-composite of multiwall carbon nanotube, decorated with NiFe2O4 nanoparticles, was synthesized with citrate sol-gel method. The multiwall carbon nanotubes decorated with NiFe2O4 nanoparticles (NiFe2O4-MWCNTs) were characterized with different methods such as Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), atomic force microscopy (AFM), vibrating sample magnetometer (VSM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The new nano-composite acts as a suitable electrocatalyst for the oxidation of sotalol at a potential of 500 mV at the surface of the modified electrode. Linear sweep voltammetry exhibited two wide linear dynamic ranges of 0.5-1000 μmol L(-1) sotalol with a detection limit of 0.09 μmol L(-1). The modified electrode was used as a novel electrochemical sensor for the determination of sotalol in real samples such as pharmaceutical, patient and safe human urine.

  11. Lipid bilayers covalently anchored to carbon nanotubes.

    PubMed

    Dayani, Yasaman; Malmstadt, Noah

    2012-05-29

    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. Multiwalled 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 α-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.

  12. Plasticity and Kinky Chemistry of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Dzegilenko, Fedor

    2000-01-01

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

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

    PubMed

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

    2012-11-27

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

  14. CARBON NANOTUBES: PROPERTIES AND APPLICATIONS

    SciTech Connect

    Fischer, John, E.

    2009-07-24

    Carbon nanotubes were discovered in 1991 as a minority byproduct of fullerene synthesis. Remarkable progress has been made in the ensuing years, including the discovery of two basic types of nanotubes (single-wall and multi-wall), great strides in synthesis and purification, elucidation of many fundamental physical properties, and important steps towards practical applications. Both the underlying science and technological potential of SWNT can profitably be studied at the scale of individual tubes and on macroscopic assemblies such as fibers. Experiments on single tubes directly reveal many of the predicted quantum confinement and mechanical properties. Semiconductor nanowires have many features in common with nanotubes, and many of the same fundamental and practical issues are in play – quantum confinement and its effect on properties; possible device structures and circuit architectures; thermal management; optimal synthesis, defect morphology and control, etc. In 2000 we began a small effort in this direction, conducted entirely by undergraduates with minimal consumables support from this grant. With DOE-BES approval, this grew into a project in parallel with the carbon nanotube work, in which we studied of inorganic semiconductor nanowire growth, characterization and novel strategies for electronic and electromechanical device fabrication. From the beginnings of research on carbon nanotubes, one of the major applications envisioned was hydrogen storage for fuel-cell powered cars and trucks. Subsequent theoretical models gave mixed results, the most pessimistic indicating that the fundamental H2-SWNT interaction was similar to flat graphite (physisorption) with only modest binding energies implying cryogenic operation at best. New material families with encouraging measured properties have emerged, and materials modeling has gained enormously in predictive power, sophistication, and the ability to treat a realistically representative number of atoms. One of

  15. A Tunable Carbon Nanotube Oscillator

    NASA Astrophysics Data System (ADS)

    Sazonova, Vera

    2005-03-01

    Nanoelectromechanical systems (NEMS) hold promise for a number of scientific and technological applications. Carbon nanotubes (NT) are perhaps the ultimate material for realizing a NEMS device as they are the stiffest material known, have low density, ultrasmall cross sections and can be defect-free. Equally important, a nanotube can act as a transistor and thus is able to sense its own motion. Here, we report the electrical actuation and detection of the guitar-string oscillation modes of doubly-clamped NT oscillators. We observed resonance frequencies in the 5MHz to 150MHz range with quality factors in the 50 to 100 range. We showed that the resonance frequencies can be widely tuned by a gate voltage. We also report on the temperature dependence of the quality factor and present a discussion of possible loss mechanisms.

  16. 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.

  17. An anticorrosive magnesium/carbon nanotube composite

    NASA Astrophysics Data System (ADS)

    Endo, M.; Hayashi, T.; Itoh, I.; Kim, Y. A.; Shimamoto, D.; Muramatsu, H.; Shimizu, Y.; Morimoto, S.; Terrones, M.; Iinou, S.; Koide, S.

    2008-02-01

    Here, we report a drastically improved anticorrosive characteristic of magnesium alloy composites with the introduction of multiwalled carbon nanotubes. Highly depressed corrosion of nanotube-filled magnesium composite in salt water is due to the formation of stable oxide films along the grain boundaries of magnesium. Our results indicate that carbon nanotube acted as effective multifunctional filler to improve both mechanical and anticorrosive performances of magnesium alloy.

  18. Covalent Sidewall Functionalization of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Chiang, I.W.; Saini, R. K.; Mickelson, E. T.; Billups, W. E.; Hauge, R. H.; Margrave, J. L.

    2001-01-01

    Progress of fluorination of single-wall carbon nanotubes is being reported. Covalent attachment of alkyl groups including methyl, n-butyl and n-hexyl groups to the sidewalls of single wall carbon nanotubes (SWNTs) has been achieved. Quantitative measurement of the alkylation was done by thermal gravimetric analysis. FTIR, Raman and UV-Vis-NIR were used to characterize these alkylated SWNTs. Application of these nanotubes are being investigated-fibers, composites, batteries, lubricants, etc.

  19. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    NASA Technical Reports Server (NTRS)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)

    2016-01-01

    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  20. Control of multiple excited image states around segmented carbon nanotubes

    SciTech Connect

    Knörzer, J. Fey, C.; Sadeghpour, H. R.; Schmelcher, P.

    2015-11-28

    Electronic image states around segmented carbon nanotubes can be confined and shaped along the nanotube axis by engineering the image potential. We show how several such image states can be prepared simultaneously along the same nanotube. The inter-electronic distance can be controlled a priori by engineering tubes of specific geometries. High sensitivity to external electric and magnetic fields can be exploited to manipulate these states and their mutual long-range interactions. These building blocks provide access to a new kind of tailored interacting quantum systems.

  1. Control of multiple excited Rydberg states around segmented carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Schmelcher, Peter; Sadeghpour, Hossein; Knoerzer, Johannes; Fey, Christian

    2016-05-01

    Electronic image Rydberg states around segmented carbon nanotubes can be confined and shaped along the nanotube axis by engineering the image potential. We show how several such image states can be prepared simultaneously along the same nanotube. The inter-electronic distance can be controlled a priori by engineering tubes of specific geometries. High sensitivity to external electric and magnetic fields can be exploited to manipulate these states and their mutual long-range interactions. These building blocks provide access to a new kind of tailored long-range interacting quantum systems.

  2. Polymer Self-assembly on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Giulianini, Michele; Motta, Nunzio

    This chapter analyses the poly(3-hexylthiophene) self-assembly on carbon nanotubes and the interaction between the two materials forming a new hybrid nanostructure. The chapter starts with a review of the several studies investigating polymers and biomolecules self-assembled on nanotubes. Then conducting polymers and polythiophenes are briefly introduced. Accordingly, carbon nanotube structure and properties are reported in Sect. 3. The experimental section starts with the bulk characterisation of polymer thin films with the inclusion of uniformly distributed carbon nanotubes. By using volume film analysis techniques (AFM, TEM, UV-Vis and Raman), we show how the polymer's higher degree of order is a direct consequence of interaction with carbon nanotubes. Nevertheless, it is through the use of nanoscale analysis and molecular dynamic simulations that the self-assembly of the polymer on the nanotube surface can be clearly evidenced and characterised. In Sect. 6, the effect of the carbon templating structure on the P3HT organisation on the surface is investigated, showing the chirality-driven polymer assembly on the carbon nanotube surface. The interaction between P3HT and CNTs brings also to charge transfer, with the modification of physical properties for both species. In particular, the alteration of the polymer electronic properties and the modification of the nanotube mechanical structure are a direct consequence of the P3HT π-π stacking on the nanotube surface. Finally, some considerations based on molecular dynamics studies are reported in order to confirm and support the experimental results discussed.

  3. Ophthalmologial Applications of Carbon Nanotube Nanotechology

    NASA Technical Reports Server (NTRS)

    Loftus, David; Girten, Beverly (Technical Monitor)

    2002-01-01

    The development of an implantable device consisting of an array of carbon nanotubes on a silicon chip for restoration of vision in patients with macular degeneration and other retinal disorders is presented. The use of carbon nanotube bucky paper for retinal cell transplantation is proposed. This paper is in viewgraph form.

  4. Making Macroscopic Assemblies of Aligned Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Smalley, Richard E.; Colbert, Daniel T.; Smith, Ken A.; Walters, Deron A.; Casavant, Michael J.; Qin, Xiaochuan; Yakobson, Boris; Hauge, Robert H.; Saini, Rajesh Kumar; Chiung, Wan-Ting; Huffman, Charles B.

    2005-01-01

    A method of aligning and assembling single-wall carbon nanotubes (SWNTs) to fabricate macroscopic structures has been invented. The method entails suspending SWNTs in a fluid, orienting the SWNTs by use of a magnetic and/or electric field, and then removing the aligned SWNTs from suspension in such a way as to assemble them while maintaining the alignment. SWNTs are essentially tubular extensions of fullerene molecules. It is desirable to assemble aligned SWNTs into macroscopic structures because the common alignment of the SWNTs in such a structure makes it possible to exploit, on a macroscopic scale, the unique mechanical, chemical, and electrical properties that individual oriented SWNTs exhibit at the molecular level. Because of their small size and high electrical conductivity, carbon nanotubes, and especially SWNTs, are useful for making electrical connectors in integrated circuits. Carbon nanotubes can be used as antennas at optical frequencies, and as probes in scanning tunneling microscopes, atomic-force microscopes, and the like. Carbon nanotubes can be used with or instead of carbon black in tires. Carbon nanotubes are useful as supports for catalysts. Ropes of SWNTs are metallic and, as such, are potentially useful in some applications in which electrical conductors are needed - for example, they could be used as additives in formulating electrically conductive paints. Finally, macroscopic assemblies of aligned SWNTs can serve as templates for the growth of more and larger structures of the same type. The great variety of tubular fullerene molecules and of the structures that could be formed by assembling them in various ways precludes a complete description of the present method within the limits of this article. It must suffice to present a typical example of the use of one of many possible variants of the method to form a membrane comprising SWNTs aligned substantially parallel to each other in the membrane plane. The apparatus used in this variant

  5. Formation of ordered ice nanotubes inside carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Koga, Kenichiro; Gao, G. T.; Tanaka, Hideki; Zeng, X. C.

    2001-08-01

    Following their discovery, carbon nanotubes have attracted interest not only for their unusual electrical and mechanical properties, but also because their hollow interior can serve as a nanometre-sized capillary, mould or template in material fabrication. The ability to encapsulate a material in a nanotube also offers new possibilities for investigating dimensionally confined phase transitions. Particularly intriguing is the conjecture that matter within the narrow confines of a carbon nanotube might exhibit a solid-liquid critical point beyond which the distinction between solid and liquid phases disappears. This unusual feature, which cannot occur in bulk material, would allow for the direct and continuous transformation of liquid matter into a solid. Here we report simulations of the behaviour of water encapsulated in carbon nanotubes that suggest the existence of a variety of new ice phases not seen in bulk ice, and of a solid-liquid critical point. Using carbon nanotubes with diameters ranging from 1.1nm to 1.4nm and applied axial pressures of 50MPa to 500MPa, we find that water can exhibit a first-order freezing transition to hexagonal and heptagonal ice nanotubes, and a continuous phase transformation into solid-like square or pentagonal ice nanotubes.

  6. Strain-modified RKKY interaction in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Gorman, P. D.; Duffy, J. M.; Power, S. R.; Ferreira, M. S.

    2015-07-01

    For low-dimensional metallic structures, such as nanotubes, the exchange coupling between localized magnetic dopants is predicted to decay slowly with separation. The long-range character of this interaction plays a significant role in determining the magnetic order of the system. It has previously been shown that the interaction range depends on the conformation of the magnetic dopants in both graphene and nanotubes. Here we examine the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in carbon nanotubes in the presence of uniaxial strain for a range of different impurity configurations. We show that strain is capable of amplifying or attenuating the RKKY interaction, significantly increasing certain interaction ranges, and acting as a switch: effectively turning on or off the interaction. We argue that uniaxial strain can be employed to significantly manipulate magnetic interactions in carbon nanotubes, allowing an interplay between mechanical and magnetic properties in future spintronic devices. We also examine the dimensional relationship between graphene and nanotubes with regards to the decay rate of the RKKY interaction.

  7. Nanocapillarity and chemistry in carbon nanotubes

    SciTech Connect

    Ugarte, D.; Chatelain, A.; Heer, W.A. de

    1996-12-13

    Open carbon nanotubes were filled with molten silver nitrate by capillary forces. Only those tubes with inner diameters of 4 nanometers or more were filled, suggesting a capillarity size dependence as a result of the lowering of the nanotube-salt interface energy with increasing curvature of the nanotube walls. Nanotube cavities should also be less chemically reactive than graphite and may serve as nanosize test tubes. This property has been illustrated by monitoring the decomposition of silver nitrate within nanotubes in situ in an electron microscope, which produced chains of silver nanobeads separated by high-pressure gas pockets. 32 refs., 3 figs.

  8. Supported Lipid Bilayer/Carbon Nanotube Hybrids

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

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

  9. Targeted Fe-filled carbon nanotube as a multifunctional contrast agent for thermoacoustic and magnetic resonance imaging of tumor in living mice.

    PubMed

    Ding, Wenzheng; Lou, Cunguang; Qiu, Jieshan; Zhao, Zongbin; Zhou, Quan; Liang, Minjie; Ji, Zhong; Yang, Sihua; Xing, Da

    2016-01-01

    Microwave-induced thermoacoustic imaging (TAI) can map the microwave absorption distribution of targets, which depends on the electrical and magnetic properties. Although carbon nanotubes (CNTs) with good electrical properties have been used as TAI contrast agents, the negligible magnetic absorption hinders its application for sensitive detection. In order to exploit CNTs with electrical and magnetic absorption properties as agent of TAI, the ferromagnetic material-filled multi-walled CNTs (MMWCNTs) are investigated. In this study, the folic acid conjugated plain multiwalled CNTs (MWCNTs) and MMWCNTs were injected through the tail-vein of mice separately, and TAI and magnetic resonance imaging (MRI) were performed. The results show the MMWCNTs can clearly image the size and edge of the tumor with the TAI contrast enhancement of 67% and T2 signal intensity decrease of four fifths compared to MWCNTs. This study demonstrated the hybrid particles have the potential to be a high-sensitive contrast agent for accurate tumor detection. From the Clinical Editor: Novel imaging modalities are emerging. Microwave-induced thermoacoustic imaging (TAI) relies on the absorption distribution of microwave of targets. In this article the authors investigate the use of ferromagnetic material-filled multi-walled CNTs as contrast agents for both TAI and MRI in an in-vivo model for tumors. The positive findings would imply that the application of dual-modality probe could provide more accurate imaging for the clinical setting.

  10. Atomic Entanglement in Carbon Nanotubes.

    NASA Astrophysics Data System (ADS)

    Bondarev, Igor; Vlahovic, Branislav

    2006-03-01

    The development of materials that may host quantum coherent states is a critical research problem for the nearest future. Recent progress in the growth of centimeter-long small-diameter single-walled carbon nanotubes (CNs)[1] and successful experiments on the encapsulation of single atoms into CNs[2], stimulate the study of dynamical quantum processes in atomically doped CN systems. We have recently shown[3] that atomic states may be strongly coupled to vacuum surface photonic modes in the CN, thus forming quasi-1D cavity polaritons similar to those observed for quantum dots in semiconductor nanocavities[4], which were recently suggested to be a possible way to produce the excitonic qubit entanglement[5]. Here, we show that, being strongly coupled to the (resonator-like) cylindrical nanotube environment, the two atomic quasi-1D polaritons can be easily entangled as well, thus challenging a novel alternative approach towards quantum information transfer over centimeter-long distances. [1]L.X.Zheng et al, Proc. Nanotech 2005 (May 8-12, 2005, Anaheim, CA, USA), vol.3, p.126. [2]G.-H.Jeong et al, Phys. Rev. B68,075410(2003). [3]I.V.Bondarev and Ph.Lambin, in: Trends in Nanotubes Reasearch (NovaScience, NY, 2005); Phys. Rev. B70,035407(2004); Phys. Rev. B72,035451(2005). [4]T.Yoshie et al, Nature 432,200(2004). [5]S.Hughes, Phys. Rev. Lett.94,227402(2005).

  11. Endohedral Impurities in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis

    2003-03-01

    A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Treating the distortion within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value g_c. The effective potential in the symmetry-broken state is found to have O(2) symmetry, in agreement with numerical calculations. The consequences of such a distortion on electronic transport will be discussed.

  12. Coated carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    2008-10-28

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

  13. Coated carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    2006-12-12

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

  14. 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.

  15. Towards chirality-pure carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhang, Yani; Zheng, Lianxi

    2010-10-01

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

  16. Carbon nanotube materials characterization and devices design

    NASA Astrophysics Data System (ADS)

    Li, Weifeng

    The objective of this research is to characterize the electrical and mechanical properties of Carbon Nanotube (CNT) materials, and explore possible device applications for these materials. In order to achieve this goal, different forms of Carbon Nanotube materials---including Carbon Nanotubes, Carbon Nanotube Arrays, Carbon Nanotube Ribbon, Carbon Nanotube Thread, and sub-micrometer Carbon Nanotube Thread---were tested under a Scanning Electron Microscope (SEM) using a Micromanipulator (MM). Video and sound recording of the testing in the microscope provided new understanding how thread is formed and how nanotube materials fail. As-produced and thermally treated nanotubes were also tested. The main electrical parameters measured were electrical resistivity and maximum current density. The main mechanical property measured was strength. Together, these parameters are helping to determine the strongest and most conductive forms of CNT material. Putting nanotube materials into application is the ultimate goal of this continuing research. Several aggressive application ideas were investigated in a preliminary way in this work. In biomedical applications, a bundle of CNTs was formed for use as an electrode for accurate biosensing. A simple robot was designed using CNT electrical fiber. The robot was powered by two solenoids and could act as an in-body sensor and actuator to perform some impossible tasks from the viewpoint of current medical technology. In aerospace engineering, CNT materials could replace copper wire to reduce the weight of aircraft. Based on the excellent mechanical properties of CNT materials, a challenging idea is to use CNT material to build elevators to move payloads to outer space without using rockets. This dissertation makes contributions in the characterization of nanotube materials and in the design of miniature electromagnetic devices.

  17. 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.

  18. Cutting single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ziegler, Kirk J.; Gu, Zhenning; Shaver, Jonah; Chen, Zheyi; Flor, Erica L.; Schmidt, Daniel J.; Chan, Candace; Hauge, Robert H.; Smalley, Richard E.

    2005-07-01

    A two-step process is utilized for cutting single-walled carbon nanotubes (SWNTs). The first step requires the breakage of carbon-carbon bonds in the lattice while the second step is aimed at etching at these damage sites to create short, cut nanotubes. To achieve monodisperse lengths from any cutting strategy requires control of both steps. Room-temperature piranha and ammonium persulfate solutions have shown the ability to exploit the damage sites and etch SWNTs in a controlled manner. Despite the aggressive nature of these oxidizing solutions, the etch rate for SWNTs is relatively slow and almost no new sidewall damage is introduced. Carbon-carbon bond breakage can be introduced through fluorination to ~C2F, and subsequent etching using piranha solutions has been shown to be very effective in cutting nanotubes. The final average length of the nanotubes is approximately 100 nm with carbon yields as high as 70-80%.

  19. Magnetic super-hydrophilic carbon nanotubes/graphene oxide composite as nanocarriers of mesenchymal stem cells: Insights into the time and dose dependences.

    PubMed

    Granato, Alessandro E C; Rodrigues, Bruno V M; Rodrigues-Junior, Dorival M; Marciano, Fernanda R; Lobo, Anderson O; Porcionatto, Marimelia A

    2016-10-01

    Among nanostructured materials, multi-walled carbon nanotubes (MWCNT) have demonstrated great potential for biomedical applications in recent years. After oxygen plasma etching, we can obtain super-hydrophilic MWCNT that contain graphene oxide (GO) at their tips. This material exhibits good dispersion in biological systems due to the presence of polar groups and its excellent magnetic properties due to metal particle residues from the catalyst that often remain trapped in its walls and tips. Here, we show for the first time a careful biological investigation using magnetic superhydrophilic MWCNT/GO (GCN composites). The objective of this study was to investigate the application of GCN for the in vitro immobilization of mesenchymal stem cells. Our ultimate goal was to develop a system to deliver mesenchymal stem cells to different tissues and organs. We show here that mesenchymal stem cells were able to internalize GCN with a consequent migration when subjected to a magnetic field. The cytotoxicity of GCN was time- and dose-dependent. We also observed that GCN internalization caused changes in the gene expression of the proteins involved in cell adhesion and migration, such as integrins, laminins, and the chemokine CXCL12, as well as its receptor CXCR4. These results suggest that GCN represents a potential new platform for mesenchymal stem cell immobilization at injury sites. PMID:27287169

  20. Preparation of High-Efficiency Cytochrome c-Imprinted Polymer on the Surface of Magnetic Carbon Nanotubes by Epitope Approach via Metal Chelation and Six-Membered Ring.

    PubMed

    Qin, Ya-Ping; Li, Dong-Yan; He, Xi-Wen; Li, Wen-You; Zhang, Yu-Kui

    2016-04-27

    A novel epitope molecularly imprinted polymer on the surface of magnetic carbon nanotubes (MCNTs@EMIP) was successfully fabricated to specifically recognize target protein cytochrome c (Cyt C) with high performance. The peptides sequences corresponding to the surface-exposed C-terminus domains of Cyt C was selected as epitope template molecule, and commercially available zinc acrylate and ethylene glycol dimethacrylate (EGDMA) were employed as functional monomer and cross-linker, respectively, to synthesize MIP via free radical polymerization. The epitope was immobilized via metal chelation and six-membered ring formed between the functional monomer and the hydroxyl and amino groups of the epitope. The resulting MCNTs@EMIP exhibited specific recognition ability toward target Cyt C including more satisfactory imprinting factor (about 11.7) than that of other reported imprinting methods. In addition, the MCNTs@EMIP demonstrated a high adsorption amount (about 780.0 mg g(-1)) and excellent selectivity. Besides, the magnetic property of the support material made the processes easy and highly efficient by assistance of an external magnetic field. High-performance liquid chromatography analysis of Cyt C in bovine blood real sample and protein mixture indicated that the specificity was not affected by other competitive proteins, which forcefully stated that the MCNTs@EMIP had potential to be applied in bioseparation area. In brief, this study provided a new protocol to detect target protein in complex sample via epitope imprinting approach and surface imprinting strategy.

  1. Optimization of carbon nanotube volume percentage for enhancement of high frequency magnetic properties of SrFe8MgCoTi2O19/MWCNTs

    NASA Astrophysics Data System (ADS)

    Gordani, Gholam Reza; Ghasemi, Ali; saidi, Ali

    2014-08-01

    A novel magnetic nanocomposite of multiwalled carbon nanotubes decorated with SrFe8MgCoTi2O19 nanoparticles have been prepared by a chemical co-precipitation method. The structural, magnetic and electromagnetic properties of samples were studied as a function of volume percentage of MWCNTs by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, vibrating sample magnetometer and vector network analysis. The XRD and FTIR results showed that the nanocomposites were synthesized successfully. Field emission scanning electron microscopy micrographs demonstrated that homogeneous and high level of dispersion of MWCNTs and Sr-hexaferrite nanoparticles in nanocomposite samples were obtained. The saturation magnetization of the nanocomposite samples was found to decrease by an increase in volume percentage of MWCNTs up to 5 vol%. The vector network analysis results show that the highest value of reflection loss of nanocomposite was -42.43 dB at 11.13 GHz with an absorption bandwidth of more than of 4 GHz. The results indicate that, these novel types of nanocomposites with appropriate amount of MWCNTs hold great promise for microwave device applications.

  2. Magnetic super-hydrophilic carbon nanotubes/graphene oxide composite as nanocarriers of mesenchymal stem cells: Insights into the time and dose dependences.

    PubMed

    Granato, Alessandro E C; Rodrigues, Bruno V M; Rodrigues-Junior, Dorival M; Marciano, Fernanda R; Lobo, Anderson O; Porcionatto, Marimelia A

    2016-10-01

    Among nanostructured materials, multi-walled carbon nanotubes (MWCNT) have demonstrated great potential for biomedical applications in recent years. After oxygen plasma etching, we can obtain super-hydrophilic MWCNT that contain graphene oxide (GO) at their tips. This material exhibits good dispersion in biological systems due to the presence of polar groups and its excellent magnetic properties due to metal particle residues from the catalyst that often remain trapped in its walls and tips. Here, we show for the first time a careful biological investigation using magnetic superhydrophilic MWCNT/GO (GCN composites). The objective of this study was to investigate the application of GCN for the in vitro immobilization of mesenchymal stem cells. Our ultimate goal was to develop a system to deliver mesenchymal stem cells to different tissues and organs. We show here that mesenchymal stem cells were able to internalize GCN with a consequent migration when subjected to a magnetic field. The cytotoxicity of GCN was time- and dose-dependent. We also observed that GCN internalization caused changes in the gene expression of the proteins involved in cell adhesion and migration, such as integrins, laminins, and the chemokine CXCL12, as well as its receptor CXCR4. These results suggest that GCN represents a potential new platform for mesenchymal stem cell immobilization at injury sites.

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

    PubMed

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

    2014-07-01

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

  4. Liquid surface model for carbon nanotube energetics.

    PubMed

    Solov'yov, Ilia A; Mathew, Maneesh; Solov'yov, Andrey V; Greiner, Walter

    2008-11-01

    In the present paper we developed a model for calculating the energy of single-wall carbon nanotubes of arbitrary chirality. This model, which we call as the liquid surface model, predicts the energy of a nanotube with relative error less than 1% once its chirality and the total number of atoms are known. The parameters of the liquid surface model and its potential applications are discussed. The model has been suggested for open end and capped nanotubes. The influence of the catalytic nanoparticle, atop which nanotubes grow, on the nanotube stability is also discussed. The suggested model gives an important insight in the energetics and stability of nanotubes of different chirality and might be important for the understanding of nanotube growth process. For the computations we use empirical Brenner and Tersoff potentials and discuss their applicability to the study of carbon nanotubes. From the calculated energies we determine the elastic properties of the single-wall carbon nanotubes (Young modulus, curvature constant) and perform a comparison with available experimental measurements and earlier theoretical predictions.

  5. Amino and thiol modified magnetic multi-walled carbon nanotubes for the simultaneous removal of lead, zinc, and phenol from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Jiang, Lili; Li, Shujun; Yu, Haitao; Zou, Zongshu; Hou, Xingang; Shen, Fengman; Li, Chuantong; Yao, Xiayan

    2016-04-01

    The novel functionalization of multi-walled carbon nanotubes (MWCNTs) was synthesized by reacting trimethoxysilylpropanethiol (MPTs), hydrazine, ammonium ferrous sulfate, and ammonium ferric sulfate in sequence as efficient ways to introduce Fe3O4, amino and thiol groups onto the nanotubes sidewalls. The magnetic MWCNTs composite material (N2H4-SH-Fe3O4/o-MWCNTs) was characterized by transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, thermo-gravimetric analysis, x-ray photoelectron spectroscopy, Fourier transformation infrared spectroscopy and magnetization curve. The results revealed that MPTs and hydrazine were coated on the surface of N2H4-SH-Fe3O4/o-MWCNTs. A series of batch adsorption experiments were conducted to study the experimental conditions, such as pH, contact time, initial concentrations and temperatures, which affected the adsorption process. The adsorption experiment results showed that the maximum equilibrium adsorption capacity of N2H4-SH-Fe3O4/o-MWCNTs for lead, zinc and phenol was 195.81 mg/g, 169.89 mg/g and 38.97 mg/g at pH 6, respectively. The adsorption isotherm was better fitted by the Freundlich model, and the adsorption kinetics was consistent with pseudo-second order kinetics model. Furthermore, thermodynamic data showed that the adsorption process was spontaneous and exothermic. These results indicated that N2H4-SH-Fe3O4/o-MWCNTs may be promising surface modified materials for removing heavy metal ions and phenol from aqueous solutions.

  6. Characterization of Carbon Nanotube Reinforced Nickel

    NASA Technical Reports Server (NTRS)

    Gill, Hansel; Hudson, Steve; Bhat, Biliyar; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    Carbon nanotubes are cylindrical molecules composed of carbon atoms in a regular hexagonal arrangement. If nanotubes can be uniformly dispersed in a supporting matrix to form structural materials, the resulting structures could be significantly lighter and stronger than current aerospace materials. Work is currently being done to develop an electrolyte-based self-assembly process that produces a Carbon Nanotube/Nickel composite material with high specific strength. This process is expected to produce a lightweight metal matrix composite material, which maintains it's thermal and electrical conductivities, and is potentially suitable for applications such as advanced structures, space based optics, and cryogenic tanks.

  7. Methods for producing reinforced carbon nanotubes

    SciTech Connect

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi

    2008-10-28

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

  8. Carbon nanotube fiber spun from wetted ribbon

    SciTech Connect

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

    2014-04-29

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

  9. Lipid nanoscaffolds in carbon nanotube arrays.

    PubMed

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

    2013-10-01

    We present the fabrication of lipid nanoscaffolds inside carbon nanotube arrays by employing the nanostructural self-assembly of lipid molecules. The nanoscaffolds are finely tunable into model biomembrane-like architectures (planar), soft nanochannels (cylindrical) or 3-dimensionally ordered continuous bilayer structures (cubic). Carbon nanotube arrays hosting the above nanoscaffolds are formed by packing of highly oriented multiwalled carbon nanotubes which facilitate the alignment of lipid nanostructures without requiring an external force. Furthermore, the lipid nanoscaffolds can be created under both dry and hydrated conditions. We show their direct application in reconstitution of egg proteins. Such nanoscaffolds find enormous potential in bio- and nano-technological fields.

  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. Metal insulator transition in vanadium dioxide nanobeams and magnetic-field asymmetry of nonlinear transport in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wei, Jiang

    This dissertation includes two research projects. The first project of vanadium dioxide nanobeams (VO2) shows that there are many advantages to be gained from working with strongly correlated materials in nanoscale crystalline form. Small VO2 single crystals display abundant new properties. It is shown that metallic and insulating phases can coexist in VO2 due to the growth introduced strain. From the simple physical system of length-confined suspended VO2 naonobeam, it is observed that metallic phase supercools and the resistivity of insulating phase remains constant when metal and insulator coexist. Most importantly, the constant resistivity indicates that the MIT in VO2 is driven by strong electron-electron interactions. Also based on the unique mechanical buckling behavior of suspended VO2 nanobeam, we developed a new way of measuring the intrinsic transition temperature Tc, which is independent of hysteresis. Beyond these findings, we proposed a new phase diagram including a stable M2 phase, which can more accurately describe and explain all the variety of behavior of VO2 nanocrystals. However, many basic question remain about the behavior of VO2 such as the detailed form of the phase diagram including the precise phase boundaries between all three phases; effects of surface energy and finite geometry, surface doping, and other parameters on stability in small crystals; and kinetics of the transition. We may hope that once the fundamental behavior of the system has been better established theoretical progress will finally be possible in understanding the basic nature of the transition. In second research project, we have carried out the first experimental study of a new transport coefficient in nanoscale devices, namely, the magnitude of the V2B term in the I-V characteristics. This coefficient provides a way to quantify the electron-electron interaction strength, which is of particular interest in our chosen system of single-walled carbon nanotubes. We also

  12. Carbon Nanotubes for Human Space Flight

    NASA Technical Reports Server (NTRS)

    Scott, Carl D.; Files, Brad; Yowell, Leonard

    2003-01-01

    Single-wall carbon nanotubes offer the promise of a new class of revolutionary materials for space applications. The Carbon Nanotube Project at NASA Johnson Space Center has been actively researching this new technology by investigating nanotube production methods (arc, laser, and HiPCO) and gaining a comprehensive understanding of raw and purified material using a wide range of characterization techniques. After production and purification, single wall carbon nanotubes are processed into composites for the enhancement of mechanical, electrical, and thermal properties. This "cradle-to-grave" approach to nanotube composites has given our team unique insights into the impact of post-production processing and dispersion on the resulting material properties. We are applying our experience and lessons-learned to developing new approaches toward nanotube material characterization, structural composite fabrication, and are also making advances in developing thermal management materials and electrically conductive materials in various polymer-nanotube systems. Some initial work has also been conducted with the goal of using carbon nanotubes in the creation of new ceramic materials for high temperature applications in thermal protection systems. Human space flight applications such as advanced life support and fuel cell technologies are also being investigated. This discussion will focus on the variety of applications under investigation.

  13. The electrical conduction variation in stained carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sun, Shih-Jye; Wei Fan, Jun; Lin, Chung-Yi

    2012-01-01

    Carbon nanotubes become stained from coupling with foreign molecules, especially from adsorbing gas molecules. The charge exchange, which is due to the orbital hybridization, occurred in the stained carbon nanotube induces electrical dipoles that consequently vary the electrical conduction of the nanotube. We propose a microscopic model to evaluate the electrical current variation produced by the induced electrical dipoles in a stained zigzag carbon nanotube. It is found that stronger orbital hybridization strengths and larger orbital energy differences between the carbon nanotube and the gas molecules help increasing the induced electrical dipole moment. Compared with the stain-free carbon nanotube, the induced electrical dipoles suppress the current in the nanotube. In the carbon nanotubes with induced dipoles the current increases as a result of increasing orbital energy dispersion via stronger hybridization couplings. In particular, at a fixed hybridization coupling, the current increases with the bond length for the donor-carbon nanotube but reversely for the acceptor-carbon nanotube.

  14. Dissymmetric carbon nanotubes by bipolar electrochemistry.

    PubMed

    Warakulwit, Chompunuch; Nguyen, Thi; Majimel, Jérome; Delville, Marie-Hélène; Lapeyre, Véronique; Garrigue, Patrick; Ravaine, Valérie; Limtrakul, Jumras; Kuhn, Alexander

    2008-02-01

    Short carbon nanotubes have been modified selectively on one end with metal using a bulk technique based on bipolar electrochemistry. A stabilized suspension of nanotubes is introduced in a capillary containing an aqueous metal salt solution, and a high electric field is applied to orientate and polarize the individual tubes. During their transport through the capillary under sufficient polarization (30 kV), each nanotube is the site of water oxidation on one end and the site of metal ion reduction on the other end with the size of the formed metal cluster being proportional to the potential drop along the nanotube.

  15. Quantum conductance of carbon nanotube peapods

    SciTech Connect

    Yoon, Young-Gui; Mazzoni, Mario S.C.; Louie, Steven G.

    2003-08-01

    We present a first-principles study of the quantum conductance of hybrid nanotube systems consisting of single-walled carbon nanotubes (SWCNTs) encapsulating either an isolated single C60 molecule or a chain of C60 molecules (nanotube peapods). The calculations show a rather weak bonding interaction between the fullerenes and the SWCNTs. The conductance of a (10,10) SWCNT with a single C60 molecule is virtually unaffected at the Fermi level, but exhibits quantized resonant reductions at the molecular levels. The nanotube peapod arrangement gives rise to high density of states for the fullerene highest occupied molecular orbital and lowest unoccupied molecular orbital bands.

  16. Microfabricated electroactive carbon nanotube actuators

    NASA Astrophysics Data System (ADS)

    Ahluwalia, Arti; Baughman, Ray H.; De Rossi, Danilo; Mazzoldi, Alberto; Tesconi, Mario; Tognetti, Alessandro; Vozzi, Giovanni

    2001-07-01

    A variety of microfabrication techniques have been developed at the University of Pisa. They are based either on pressure or piston actuated microsyringes or modified ink-jet printers. This work present the results of a study aimed at fabricating carbon nanotube (NT) actuators using micro-syringes. In order to prevent the nanotubes from aggregating into clumps, they were enclosed in a partially cross-linked polyvinylalcohol - polyallylamine matrix. After sonication the solution remained homogenously dispersed for about 40 minutes, which was sufficient time for deposition. Small strips of NT, about 5 mm across and 15 mm long were deposited. Following deposition, the films were baked at 80 degree(s)C and their thickness, impedance and mechanical resistance measured. The results indicate that 50 minutes of baking time is sufficient to give a constant resistivity of 1.12 x 10-2 (Omega) m per layer similar to a typical semiconductor, and each layer has a thickness of about 6 micrometers .

  17. Carbon nanotube transistors, sensors, and beyond

    NASA Astrophysics Data System (ADS)

    Zhou, Xinjian

    Carbon nanotubes are tiny hollow cylinders, made from a single graphene sheet, that possess many amazing properties. Another reason why nanotubes have generated intense research activities from scientists of various disciplines is they represent a new class of materials for the study of one-dimensional physics. In this thesis we investigate the electrical transport of semiconducting single-walled carbon nanotubes and their potential applications as biological sensors. Electrons have been predicted, by theoretical physicists, to go through nanotubes without much resistance. But this has not been properly quantified experimentally, and the origin of the routinely observed large resistance in nanotubes is not clear. In this thesis we show that in moderate long high quality nanotubes the electrical transport is limited by electron-phonon scattering. Systematic studies are carried out using many devices of different diameters at various temperatures. The resistance and inverse of peak mobility are observed to decrease linearly with temperature, indicating the influence of phonons. The conductance and peak mobility scales with nanotube diameters also, in a linear fashion and quadratic fashion respectively. Based on electron-phonon scattering, a theory model is developed that can not only predict how the resistance changes with gate voltage but also explain the observed temperature and diameter dependence. This work clarifies the nature of electrical transport in nanotubes and sets a performance limit of nanotube devices in diffusive regime. The electrical transport in nanotubes is extremely sensitive to local electrostatic environment due to their small size, large surface to volume ratio and high mobility, making nanotubes ideal key elements in biological sensors. In the second part of this thesis, we integrate nanotubes with supported lipid bilayers, mimic structures of cell membranes, and use this platform as a way to introduce biomolecules into the vicinity of

  18. Carbon Nanotube Composites: Strongest Engineering Material Ever?

    NASA Technical Reports Server (NTRS)

    Mayeaux, Brian; Nikolaev, Pavel; Proft, William; Nicholson, Leonard S. (Technical Monitor)

    1999-01-01

    The primary goal of the carbon nanotube project at Johnson Space Center (JSC) is to fabricate structural materials with a much higher strength-to-weight ratio than any engineered material today, Single-wall nanotubes present extraordinary mechanical properties along with new challenges for materials processing. Our project includes nanotube production, characterization, purification, and incorporation into applications studies. Now is the time to move from studying individual nanotubes to applications work. Current research at JSC focuses on structural polymeric materials to attempt to lower the weight of spacecraft necessary for interplanetary missions. These nanoscale fibers present unique new challenges to composites engineers. Preliminary studies show good nanotube dispersion and wetting by the epoxy materials. Results of tensile strength tests will also be reported. Other applications of nanotubes are also of interest for energy storage, gas storage, nanoelectronics, field emission, and biomedical uses.

  19. Deconvoluting hepatic processing of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Alidori, Simone; Bowman, Robert L.; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J. Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L. J.; Ulmert, Hans David S.; Brea, Elliott J.; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A.; McDevitt, Michael R.

    2016-07-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans.

  20. Photonics based on carbon nanotubes

    PubMed Central

    2013-01-01

    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. PMID:23803293

  1. Functionalized carbon nanotubes: biomedical applications

    PubMed Central

    Vardharajula, Sandhya; Ali, Sk Z; Tiwari, Pooja M; Eroğlu, 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

  2. 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.

  3. Carbon nanotube heat-exchange systems

    DOEpatents

    Hendricks, Terry Joseph; Heben, Michael J.

    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).

  4. Carbon nanotube polymer composition and devices

    DOEpatents

    Liu, Gao; Johnson, Stephen; Kerr, John B.; Minor, Andrew M.; Mao, Samuel S.

    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.

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

    PubMed

    Daneshvar Tarigh, Ghazale; Shemirani, Farzaneh

    2013-10-15

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

  6. Solid phase extraction of amoxicillin using dibenzo-18-crown-6 modified magnetic-multiwalled carbon nanotubes prior to its spectrophotometric determination.

    PubMed

    Ahmadi, Mazaher; Madrakian, Tayyebeh; Afkhami, Abbas

    2016-01-01

    This work reports on a method for selective extraction and sensitive determination of amoxicillin drug (AMX). The method is based on solid phase extraction of AMX by a novel modified magnetic nanoadsorbent prior to spectrophotometric determination of AMX using a procedure based on formation a colored azo-derivative of the investigated drug. The nanoadsorbent has been synthesized by modification of magnetic-multiwalled carbon nanotube with dibenzo-18-crown-6 moieties. The synthesized nanoparticles were characterized using TEM, XRD and FT-IR measurements. At the next step, various factors that could potentially affect adsorption and desorption efficiencies of AMX, have been optimized. The results showed that under the optimized conditions, sensitive and selective determination of the investigated drug in concentration range of 5.0-1000.0 ng mL(-1) with the limit of detection of 3.0 ng mL(-1) was achievable. Furthermore, the real sample analysis (i.e. amoxicillin capsules and human urine samples) results indicated that a reliable promising candidate method has been developed for the determination of AMX in the investigated real samples.

  7. Magnetic N-doped carbon nanotubes: A versatile and efficient material for the determination of polycyclic aromatic hydrocarbons in environmental water samples.

    PubMed

    Menezes, Helvécio Costa; de Barcelos, Stella Maris Resende; Macedo, Damiana Freire Dias; Purceno, Aluir Dias; Machado, Bruno Fernades; Teixeira, Ana Paula Carvalho; Lago, Rochel Monteiro; Serp, Philippe; Cardeal, Zenilda Lourdes

    2015-05-11

    This paper describes a new, efficient and versatile method for the sampling and preconcentration of PAH in environmental water matrices using special hybrid magnetic carbon nanotubes. These N-doped amphiphilic CNT can be easily dispersed in any aqueous matrix due to the N containing hydrophilic part and at the same time show high efficiency for the adsorption of different PAH contaminants due to the very hydrophobic surface. After adsorption, the CNT can be easily removed from the medium by a simple magnetic separation. GC/MS analyses showed that the CNT method is more efficient than the use of polydimethylsiloxane (PDMS) with much lower solvent consumption, technical simplicity and time, showing good linearity (range 0.18-80.00 μg L(-1)) and determination coefficient (R(2) > 0.9810). The limit of detection ranged from 0.05 to 0.42 μg L(-1) with limit of quantification from 0.18 to 1.40 μg L(-1). Recovery (n=9) ranged from 80.50 ± 10 to 105.40 ± 12%. Intraday precision (RSD, n=9) ranged from 1.91 to 9.01%, whereas inter day precision (RSD, n=9) ranged from 7.02 to 17.94%. The method was applied to the analyses of PAH in four lake water samples collected in Belo Horizonte City, Brazil.

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

    PubMed

    Daneshvar Tarigh, Ghazale; Shemirani, Farzaneh

    2013-10-15

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

  10. 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; Milić, 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

  11. Ultralong single-wall carbon nanotubes.

    PubMed

    Zheng, L X; O'Connell, M J; Doorn, S K; Liao, X Z; Zhao, Y H; Akhadov, E A; Hoffbauer, M A; Roop, B J; Jia, Q X; Dye, R C; Peterson, D E; Huang, S M; Liu, J; Zhu, Y T

    2004-10-01

    Since the discovery of carbon nanotubes in 1991 by Iijima, there has been great interest in creating long, continuous nanotubes for applications where their properties coupled with extended lengths will enable new technology developments. For example, ultralong nanotubes can be spun into fibres that are more than an order of magnitude stronger than any current structural material, allowing revolutionary advances in lightweight, high-strength applications. Long metallic nanotubes will enable new types of micro-electromechanical systems such as micro-electric motors, and can also act as a nanoconducting cable for wiring micro-electronic devices. Here we report the synthesis of 4-cm-long individual single-wall carbon nanotubes (SWNTs) at a high growth rate of 11 microm s(-1) by catalytic chemical vapour deposition. Our results suggest the possibility of growing SWNTs continuously without any apparent length limitation.

  12. An ultrasensitive sandwich-type electrochemical immunosensor based on signal amplification strategy of gold nanoparticles functionalized magnetic multi-walled carbon nanotubes loaded with lead ions.

    PubMed

    Li, Faying; Han, Jian; Jiang, Liping; Wang, Yulan; Li, Yueyun; Dong, Yunhui; Wei, Qin

    2015-06-15

    In this study, a novel and ultrasensitive sandwich-type electrochemical immunosensor was prepared for the quantitative detection of alpha fetoprotein (AFP), a well-known hepatocellular carcinoma biomarker. Gold nanoparticles (Au NPs) functionalized magnetic multi-walled carbon nanotubes (MWCNTs-Fe3O4) were prepared and utilized for the adsorption of lead ions (Pb(2+)) and the secondary antibodies (Ab2). The resultant nanocomposites (Pb(2+)@Au@MWCNTs-Fe3O4) were used as the label for signal amplification, showing better electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) than MWCNTs, MWCNTs-Fe3O4 or Au@MWCNTs-Fe3O4 due to the synergetic effect presented in Pb(2+)@Au@MWCNTs-Fe3O4. Moreover, Au NPs were electrodeposited on the surface of glassy carbon electrode (GCE) for the effective immobilization of primary antibodies (Ab1). Under the optimal conditions, a linear range from 10 fg/mL to 100 ng/mL and a detection limit of 3.33 fg/mL were obtained. The proposed electrochemical sandwich-type immunosensor shows high sensitivity, good selectivity and stability for the quantitative detection of AFP, holding a great potential in clinical and diagnostic applications.

  13. One-Step Fabrication of a Multifunctional Magnetic Nickel Ferrite/Multi-walled Carbon Nanotubes Nanohybrid-Modified Electrode for the Determination of Benomyl in Food.

    PubMed

    Wang, Qiong; Yang, Jichun; Dong, Yuanyuan; Zhang, Lei

    2015-05-20

    Benomyl, as one kind of agricultural pesticide, has adverse impact on human health and the environment. It is urgent to develop effective and rapid methods for quantitative determination of benomyl. A simple and sensitive electroanalytical method for determination of benomyl using a magnetic nickel ferrite (NiFe2O4)/multi-walled carbon nanotubes (MWCNTs) nanohybrid-modified glassy carbon electrode (GCE) was presented. The electrocatalytic properties and electroanalysis of benomyl on the modified electrode were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In the phosphate-buffered saline (PBS) of pH 6.0, this constructed biosensor exhibited two linear relationships with the benomyl concentration range from 1.00 × 10(-7) to 5.00 × 10(-7) mol/L and from 5.00 × 10(-7) to 1.00 × 10(-5) mol/L, respectively. The detection limit was 2.51 × 10(-8) mol/L (S/N = 3). Moreover, the proposed method was successfully applied to determine benomyl in real samples with satisfactory results. The NiFe2O4/MWCNTs/GCE showed good reproducibility and stability, excellent catalytic activity, and anti-interference.

  14. Carbon nanotube temperature and pressure sensors

    DOEpatents

    Ivanov, Ilia N.; Geohegan, David B.

    2016-10-25

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

  15. Carbon nanotube temperature and pressure sensors

    DOEpatents

    Ivanov, Ilia N; Geohegan, David Bruce

    2013-10-29

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

  16. Controlled Deposition and Alignment of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  17. [Hygienic evaluation of multilayer carbon nanotubes].

    PubMed

    Haliullin, T O; Zalyalov, R R; Shvedova, A A; Tkachov, A G

    2015-01-01

    The authors demonstrate that traditional methods evaluating work conditions on contemporary innovative enterprises producing nanomaterials assess these conditions as harmless and safe. At the same time, special investigation methods enable to reveal new hazards for workers' health: the study results prove that workers engaged into multilayer carbon nanotubes production are exposed to multilayer carbon nanotubes aerosols in concentrations exceeding internationally acceptable levels of 1 μg/ml (NIOSH)--that can harm the workers' health.

  18. Controlled Deposition and Alignment of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige

    1999-01-01

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

  20. 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.

  1. Interfaces Between Carbon Nanotubes and Nickel Nanoparticles in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Liu, Bai; Liu, Lirui

    2013-12-01

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

  2. Effect of functionalization of carbon nanotubes with psychosine on complement activation and protein adsorption.

    PubMed

    Rybak-Smith, Malgorzata J; Tripisciano, Carla; Borowiak-Palen, Ewa; Lamprecht, Constanze; Sim, Robert B

    2011-12-01

    Carbon nanotubes possess interesting physicochemical properties which make them potentially usable in medicine. Single-walled carbon nanotubes and multi-walled carbon nanotubes, for example, may carry and deliver anticancer drugs, such as cisplatin. Magnetic nanoparticles, like iron filled MWCNT, can be used in hyperthermia therapy. However, their hydrophobic character is a major difficulty, as preparation of stable dispersions of carbon nanotubes in biological buffers is an essential step towards biomedical applications. Recently, a novel treatment using the glycolipid, Galactosyl-beta1-sphingosine (psychosine), was employed to make stable suspensions of psychosine-functionalized carbon nanotubes in biological buffers. In this paper, the interactions of psychosine-functionalized carbon nanotubes with a part of the human immune system, complement, is presented. To investigate if human serum complement proteins can interact with psychosine-functionalized carbon nanotubes, complement consumption (depletion) assays were conducted. Moreover, direct protein binding studies, to analyze the interaction of plasma proteins with the psychosine-functionalized carbon nanotubes, using affinity chromatography and sodium dodecyl sulphate polyacrylamide gel electrophoresis techniques, were applied. The psychosine-functionalized carbon nanotubes activate human complement via the classical pathway. Interestingly, as the hydrophilic part of the glycolipid may bind to ficolins, the lectin pathway could also be involved. Binding of human plasma proteins is very selective as only very few proteins adsorb to the psychosine-functionalized carbon nanotube surface, when placed in contact with human plasma. Bovine serum albumin-coated carbon nanotubes were used as a standard to find the differences in complement activation and protein adsorption patterns, caused by various non-covalent coatings of carbon nanotubes.

  3. Filling of carbon nanotubes and nanofibres

    PubMed Central

    Gately, Reece D

    2015-01-01

    Summary 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

  4. Hydrophilic multi-walled carbon nanotubes decorated with magnetite nanoparticles as lymphatic targeted drug delivery vehicles.

    PubMed

    Yang, Dong; Yang, Feng; Hu, Jianhua; Long, Jiang; Wang, Changchun; Fu, Deliang; Ni, Quanxing

    2009-08-01

    Hydrophilic multi-walled carbon nanotubes decorated with magnetite nanoparticles were readily taken up into lymph vessels and delivered gemcitabine to lymph nodes with high efficiency under the guidance of a magnetic field.

  5. Method for manufacturing high quality carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Benavides, Jeanette M. (Inventor)

    2006-01-01

    A non-catalytic process for the production of carbon nanotubes includes supplying an electric current to a carbon anode and a carbon cathode which have been securely positioned in the open atmosphere with a gap between them. The electric current creates an electric arc between the carbon anode and the carbon cathode, which causes carbon to be vaporized from the carbon anode and a carbonaceous residue to be deposited on the carbon cathode. Inert gas is pumped into the gap to flush out oxygen, thereby preventing interference with the vaporization of carbon from the anode and preventing oxidation of the carbonaceous residue being deposited on the cathode. The anode and cathode are cooled while electric current is being supplied thereto. When the supply of electric current is terminated, the carbonaceous residue is removed from the cathode and is purified to yield carbon nanotubes.

  6. Method for nano-pumping using carbon nanotubes

    DOEpatents

    Insepov, Zeke; Hassanein, Ahmed

    2009-12-15

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

  7. Fast readout of carbon nanotube mechanical resonators

    NASA Astrophysics Data System (ADS)

    Meerwaldt, Harold; Singh, Vibhor; Schneider, Ben; Schouten, Raymond; van der Zant, Herre; Steele, Gary

    2013-03-01

    We perform fast readout measurements of carbon nanotube mechanical resonators. Using an electronic mixing scheme, we can detect the amplitude of the mechanical motion with an intermediate frequency (IF) of 46 MHz and a timeconstant of 1 us, up to 5 orders of magnitude faster than before. Previous measurements suffered from a low bandwidth due to the combination of the high resistance of the carbon nanotube and a large stray capacitance. We have increased the bandwidth significantly by using a high-impedance, close-proximity HEMT amplifier. The increased bandwidth should allow us to observe the nanotube's thermal motion and its transient response, approaching the regime of real-time detection of the carbon nanotube's mechanical motion.

  8. Carbon Nanotube Based Microfluidic Elements for Filtration and Concentration

    SciTech Connect

    Bakajin, O; Ben-Barak, N; Peng, J; Noy, A

    2003-06-25

    We have developed a method for integration of patterned arrays of carbon nanotubes or the ''nanotube mesh'' into microfabricated channels. The method includes standard lithographic methods for patterning and etching the substrate, followed by catalyst patterning, CVD deposition of nanotubes, and anodic bonding of coverslip top. We will describe a carbon nanotube filtering device fabricated using this method and discuss the use of carbon nanotube arrays as molecular concentration and separation media.

  9. Polymerization initated at sidewalls of carbon nanotubes

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  10. Trapping cold atoms using surface-grown carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Petrov, P. G.; Machluf, S.; Younis, S.; Macaluso, R.; David, T.; Hadad, B.; Japha, Y.; Keil, M.; Joselevich, E.; Folman, R.

    2009-04-01

    We present a feasibility study for loading cold atomic clouds into magnetic traps created by single-wall carbon nanotubes grown directly onto dielectric surfaces. We show that atoms may be captured for experimentally sustainable nanotube currents, generating trapped clouds whose densities and lifetimes are sufficient to enable detection by simple imaging methods. This opens the way for a different type of conductor to be used in atomchips, enabling atom trapping at submicron distances, with implications for both fundamental studies and for technological applications.

  11. A novel polymeric ionic liquid-coated magnetic multiwalled carbon nanotubes for the solid-phase extraction of Cu, Zn-superoxide dismutase.

    PubMed

    Wen, Qian; Wang, Yuzhi; Xu, Kaijia; Li, Na; Zhang, Hongmei; Yang, Qin

    2016-10-01

    A novel magnetic adsorbent, benzyl groups functionalized imidazolium-based polymeric ionic liquid (PIL)-coated magnetic multiwalled carbon nanotubes (MWCNTs) (m-MWCNTs@PIL), has been successfully synthesized and applied for the extraction of Cu, Zn-superoxide dismutase (Cu, Zn-SOD). The m-MWCNTs@PIL were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), thermal gravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM) and zeta-potential nanoparticles. In this method, the m-MWCNTs@PIL could interact with Cu, Zn-SOD through hydrogen bonding, π-π and electrostatic interactions. The extraction performance of the m-MWCNTs@PIL in the magnetic solid-phase extraction (MSPE) procedure was investigated, coupled with the determination by UV-vis spectrophotometer. Compared with m-MWCNTs@IL and m-MWCNTs, the m-MWCNTs@PIL exhibited the highest extraction capacity of 29.1 mg/g for Cu, Zn-SOD. The adsorbed Cu, Zn-SOD remained high specific activity after being eluted from m-MWCNTs@PIL by 1 moL/L NaCl solution. Besides, the m-MWCNTs@PIL could be easily recycled and successfully employed in the extraction of Cu, Zn-SOD from real samples. Under the optimal conditions, the precision, repeatability and stability of the proposed method were investigated and the RSDs were 0.29%, 1.68% and 0.54%, respectively. Recoveries were in the range of 82.7-102.3%, with the RSD between 3.47% and 5.35%. On the basis of these results, the developed method has great potential in the extraction of Cu, Zn-SOD or other analytes from biological samples. PMID:27639143

  12. 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 π 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 σ 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.

  13. Modeling of carbon nanotubes and carbon nanotube-polymer composites

    NASA Astrophysics Data System (ADS)

    Pal, G.; Kumar, S.

    2016-01-01

    In order to meet stringent environmental, safety and performance requirements from respective regulatory bodies, various technology-based industries are promoting the use of advanced carbon nanotube (CNT) reinforced lightweight and high strength polymer nanocomposites (PNCs) as a substitute to conventional materials both in structural and non-structural applications. The superior mechanical properties of PNCs made up of CNTs or bundles of CNTs can be attributed to the interfacial interaction between the CNTs and matrix, CNT's morphologies and to their uniform dispersion in the matrix. In PNCs, CNTs physically bond with polymeric matrix at a level where the assumption of continuum level interactions is not applicable. Modeling and prediction of mechanical response and failure behavior of CNTs and their composites becomes a complex task and is dealt with the help of up-scale modeling strategies involving multiple spatial and temporal scales in hierarchical or concurrent manner. Firstly, the article offers an insight into various modeling techniques in studying the mechanical response of CNTs; namely, equivalent continuum approach, quasi-continuum approach and molecular dynamics (MD) simulation. In the subsequent steps, these approaches are combined with analytical and numerical micromechanics models in a multiscale framework to predict the average macroscopic response of PNCs. The review also discusses the implementation aspects of these computational approaches, their current status and associated challenges with a future outlook.

  14. Carbon nanotube biocompatibility with cardiac muscle cells

    NASA Astrophysics Data System (ADS)

    Garibaldi, Silvano; Brunelli, Claudio; Bavastrello, Valter; Ghigliotti, Giorgio; Nicolini, Claudio

    2006-01-01

    Purified carbon nanotubes are new carbon allotropes, sharing similarities with graphite, that have recently been proposed for their potential use with biological systems as probes for in vitro research and for diagnostic and clinical purposes. However the biocompatibility of carbon nanotubes with cells represents an important problem that, so far, remains largely uninvestigated. The objective of this in vitro study is to explore the cytocompatibility properties of purified carbon nanofibres with cardiomyocytes. Cardiac muscle cells from a rat heart cell line H9c2 (2-1) have been used. Highly purified single-walled nanotubes (SWNTs) were suspended at the concentration of 0.2 mg ml-1 by ultrasound in complete Dulbecco's modified Eagle's medium, and administered to cells to evaluate cell proliferation and shape changes by light microscopy, cell viability by trypan blue exclusion, and apoptosis, determined flow cytometrically by annexin/PI staining. Microscopic observation evidenced that carbon nanotubes bind to the cell membrane, causing a slight modification in cell shape and in cell count only after three days of treatment. Cell viability was not affected by carbon nanotubes in the first three days of culture, while after this time, cell death was slightly higher in nanotube-treated cells (p = ns). Accordingly, nanotube treatment induced little and non-significant change in the apoptotic cell number at day 1 and 3. The effect of nanotubes bound to cells was tested by reseeding treated cardiomyocytes. Cells from a trypsinized nanotube-treated sample showed a limited ability to proliferate, and a definite difference in shape, with a high degree of cell death: compared to reseeded untreated ones, in SWNT-treated samples the annexin-positive/PI-negative cells increased from 2.9% to 9.3% in SWNT (p<0.05, where p<0.05 defines a statistically significant difference with a probability above 95%), and the annexin-positive/PI-positive cells increased from 5.2% to 18.7% (p<0

  15. 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

  16. Carbon nanotube ecotoxicity in amphibians: assessment of multiwalled carbon nanotubes and comparison with double-walled carbon nanotubes.

    PubMed

    Mouchet, Florence; Landois, Perine; Puech, Pascal; Pinelli, Eric; Flahaut, Emmanuel; Gauthier, Laury

    2010-08-01

    The potential impact of industrial multiwalled carbon nanotubes (MWNTs) was investigated under normalized laboratory conditions according to the International Standard micronucleus assay ISO 21427-1 for 12 days of half-static exposure to 0.1, 1, 10 and 50 mg/l of MWNTs in water. Three different end points were carried out for 12 days of exposure: mortality, growth inhibition and micronuclei induction in erythrocytes of the circulating blood of larvae. Raman spectroscopy analysis was used to study the presence of carbon nanotubes in the biological samples. Considering the high diversity of carbon nanotubes according to their different characteristics, MWNTs were analyzed in Xenopus larvae, comparatively to double-walled carbon nanotubes used in a previous study in similar conditions. Growth inhibition in larvae exposed to 50 mg/l of MWNTs was evidenced; however, no genetoxicity (micronucleus assay) was noticed, at any concentration. Carbon nanotube localization in the larvae leads to different possible hypothesis of mechanisms explaining toxicity in Xenopus.

  17. Carbon Nanotube-Based Synthetic Gecko Tapes

    NASA Astrophysics Data System (ADS)

    Dhinojwala, Ali

    2008-03-01

    Wall-climbing geckos have unique ability to attach to different surfaces without the use of any viscoelastic glues. On coming in contact with any surface, the micron-size gecko foot-hairs deform, enabling molecular contact over large areas, thus translating weak van der Waals (vdW) interactions into enormous shear forces. We will present our recent results on the development of synthetic gecko tape using aligned carbon nanotubes to mimic the keratin hairs found on gecko feet. The patterned carbon nanotube-based 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 micron-size setae (replicated by nanotube bundles) and nanometer-size spatulas (individual nanotubes) are necessary to achieve macroscopic shear adhesion and to translate the weak vdW interactions into high shear forces. The carbon nanotube based tape offers an excellent synthetic option as a dry conductive reversible adhesive in microelectronics, robotics and space applications. The mechanism behind these large shear forces and self-cleaning properties of these carbon nanotube based synthetic gecko tapes will be discussed. This work was performed in collaboration with graduate students Liehui Ge, and Sunny Sethi, and collaborators from RPI; Lijie Ci and Professor Pulickel Ajayan.

  18. Physical removal of metallic carbon nanotubes from nanotube network devices using a thermal and fluidic process.

    PubMed

    Ford, Alexandra C; Shaughnessy, Michael; Wong, Bryan M; Kane, Alexander A; Kuznetsov, Oleksandr V; Krafcik, Karen L; Billups, W Edward; Hauge, Robert H; Léonard, François

    2013-03-15

    Electronic and optoelectronic devices based on thin films of carbon nanotubes are currently limited by the presence of metallic nanotubes. Here we present a novel approach based on nanotube alkyl functionalization to physically remove the metallic nanotubes from such network devices. The process relies on preferential thermal desorption of the alkyls from the semiconducting nanotubes and the subsequent dissolution and selective removal of the metallic nanotubes in chloroform. The approach is versatile and is applied to devices post-fabrication.

  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 μM), 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%

  20. Selective Functionalization of Carbon Nanotubes: Part II

    NASA Technical Reports Server (NTRS)

    Meyyappan, Meyya; Khare, Bishun

    2010-01-01

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

  1. 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.

  2. 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 ...

  3. Methods for Gas Sensing with Single-Walled Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama B. (Inventor)

    2013-01-01

    Methods for gas sensing with single-walled carbon nanotubes are described. The methods comprise biasing at least one carbon nanotube and exposing to a gas environment to detect variation in temperature as an electrical response.

  4. A carbon nanotube wall membrane for water treatment.

    PubMed

    Lee, Byeongho; Baek, Youngbin; Lee, Minwoo; Jeong, Dae Hong; Lee, Hong H; Yoon, Jeyong; Kim, Yong Hyup

    2015-05-14

    Various forms of carbon nanotubes have been utilized in water treatment applications. The unique characteristics of carbon nanotubes, however, have not been fully exploited for such applications. Here we exploit the characteristics and corresponding attributes of carbon nanotubes to develop a millimetre-thick ultrafiltration membrane that can provide a water permeability that approaches 30,000 l m(-2) h(-1) bar(-1), compared with the best water permeability of 2,400 l m(-2) h(-1) bar(-1) reported for carbon nanotube membranes. The developed membrane consists only of vertically aligned carbon nanotube walls that provide 6-nm-wide inner pores and 7-nm-wide outer pores that form between the walls of the carbon nanotubes when the carbon nanotube forest is densified. The experimental results reveal that the permeance increases as the pore size decreases. The carbon nanotube walls of the membrane are observed to impede bacterial adhesion and resist biofilm formation.

  5. 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.

  6. Carbon Nanotube-Based Permeable Membranes

    SciTech Connect

    Holt, J K; Park, H G; Bakajin, O; Noy, A; Huser, T; Eaglesham, D

    2004-04-06

    A membrane of multiwalled carbon nanotubes embedded in a silicon nitride matrix was fabricated for use in studying fluid mechanics on the nanometer scale. Characterization by fluorescent tracer diffusion and scanning electron microscopy suggests that the membrane is void-free near the silicon substrate on which it rests, implying that the hollow core of the nanotube is the only conduction path for molecular transport. Assuming Knudsen diffusion through this nanotube membrane, a maximum helium transport rate (for a pressure drop of 1 atm) of 0.25 cc/sec is predicted. Helium flow measurements of a nanoporous silicon nitride membrane, fabricated by sacrificial removal of carbon, give a flow rate greater than 1x10{sup -6} cc/sec. For viscous, laminar flow conditions, water is estimated to flow across the nanotube membrane (under a 1 atm pressure drop) at up to 2.8x10{sup -5} cc/sec (1.7 {micro}L/min).

  7. 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.

  8. Nickel Nanoparticles Entangled in Carbon Nanotubes: Novel Ink for Nanotube Printing.

    PubMed

    Abdel Fattah, Abdel Rahman; Majdi, Tahereh; Abdalla, Ahmed M; Ghosh, Suvojit; Puri, Ishwar K

    2016-01-27

    We report the serendipitous discovery of a rapid and inexpensive method to attach nanoscale magnetic chaperones to carbon nanotubes (CNTs). Nickel nanoparticles (NiNPs) become entangled in CNTs after both are dispersed in kerosene by sonication and form conjugates. An externally applied magnetic field manipulates the resulting CNTs-NiNP ink without NiNP separation, allowing us to print an embedded circuit in an elastomeric matrix and fabricate a strain gage and an oil sensor. The new method to print a circuit in a soft material using an NiNP-CNT ink is more rapid and inexpensive than the complex physical and chemical means typically used to magnetize CNTs.

  9. Electrical switching in metallic carbon nanotubes

    SciTech Connect

    Son, Young-Woo; Ihm, Jisoon; Cohen, Marvin L.; Louie, Steven G.; Choi, Hyoung Joon

    2005-04-15

    We present first-principles calculations of quantumtransport that show that the resistance of metallic carbon nanotubes canbe changed dramatically with homogeneous transverse electric fields ifthe nanotubes have impurities or defects. The change of the resistance ispredicted to range over more than 2 orders of magnitude withexperimentally attainable electric fields. This novel property has itsorigin that backscattering of conduction electrons by impurities ordefects in the nanotubes is strongly dependent on the strength and/ordirection of the applied electric fields. We expect this property to opena path to new device applications of metallic carbonnanotubes.

  10. Agglomeration defects on irradiated carbon nanotubes

    SciTech Connect

    Steini Moura, Cassio; Balzaretti, Naira Maria; Amaral, Livio; Gribel Lacerda, Rodrigo; Pimenta, Marcos A.

    2012-03-15

    Aligned carbon nanotubes (CNT) were irradiated in the longitudinal and perpendicular directions, with low energy carbon and helium ions in order to observe the formation of defects in the atomic structure. Analysis through Raman spectroscopy and scanning electron microscopy indicated bundle rupture and ion track formation on nanotube bundles. Aligned CNT presented a kind of defect comprising ravine formation and tube agglomeration on top of the substrate. The latter structure is possibly caused by static charge accumulation induced by the incoming ions. Fluence plays a role on the short range order. Higher fluence irradiation transforms CNT into amorphous carbon nanowires.

  11. Does water dope carbon nanotubes?

    SciTech Connect

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

    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.

  12. Bending fracture in carbon nanotubes.

    PubMed

    Kuo, Wen-Shyong; Lu, Hsin-Fang

    2008-12-10

    A novel approach was adopted to incur bending fracture in carbon nanotubes (CNTs). Expanded graphite (EG) was made by intercalating and exfoliating natural graphite flakes. The EG was deposited with nickel particles, from which CNTs were grown by chemical vapor deposition. The CNTs were tip-grown, and their roots were fixed on the EG flakes. The EG flakes were compressed, and many CNTs on the surface were fragmented due to the compression-induced bending. Two major modes of the bending fracture were observed: cone-shaped and shear-cut. High-resolution scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the crack growth within the graphene layers. The bending fracture is characterized by two-region crack growth. An opening crack first appears around the outer-tube due to the bending-induced tensile stress. The crack then branches to grow along an inclined direction toward the inner-tube due to the presence of the shear stress in between graphene layers. An inner-tube pullout with inclined side surface is formed. The onset and development of the crack in these two regions are discussed. PMID:21730690

  13. Thermal Transport in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Christman, Jeremy; Moore, Andrew; Khatun, Mahfuza

    2011-10-01

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

  14. Elastomer Reinforced with Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Hudson, Jared L.; Krishnamoorti, Ramanan

    2009-01-01

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

  15. Electrical properties of multiwalled carbon nanotube film

    SciTech Connect

    Antonenko, S. V. Malinovskaya, O. S.; Mal'tsev, S. N.

    2007-07-15

    The multiwalled carbon nanotube films examined in this study are produced by two methods: current annealing of carbon paper and dc magnetron sputtering. The conductivity and the temperature dependence of resistance of the samples are measured. The thermal conductivity of the film-substrate system is evaluated.

  16. Bio-functionalization of multi-walled carbon nanotubes.

    PubMed

    Majumder, Anindya; Khazaee, Maryam; Opitz, Jörg; Beyer, Eckhard; Baraban, Larysa; Cuniberti, Gianaurelio

    2013-10-28

    Here we present a hybrid approach to functionalize multi-walled carbon nanotubes in aqueous solution, exploring a non-covalent binding strategy. We focus on formation of hybrid complexes consisting of carbon nanotubes decorated by single stranded DNA, non-covalently attached using surfactants as intermediate layers. Unlike single walled carbon nanotubes, revealing easy side wall wrapping of DNA, we observe that wrapping of nucleic acids around multi-walled carbon nanotubes is diameter dependent. PMID:24013382

  17. Magneto Themoelectric Generator with Carbon Nanotube Thermal Interfaces

    NASA Astrophysics Data System (ADS)

    McCarthy, Patrick T.; Fisher, Timothy S.; Marinero, Ernesto E.

    2013-03-01

    We report the thermal behavior of Gd foils used in a magneto thermoelectric generator cells. The device exploits the ferromagnetic phase transition of gadolinium to drive the movement of a diaphragm ``shuttle'' whose mechanical energy is converted to electrical form and which enhances heat transfer through both conduction and convection. Efficient heat transfer at mechanical interfaces is critical to increase shuttle speed and the commensurate rate of heat transfer. The synthesis and characterization of carbon nanotube thermal interfaces for the Gd foils are described. The samples generated in this study were consistently measured with total thermal interface resistances in the range of 65-105 mm2 K/W, a reduction of 55-70% compared to bare Gd (Rint ~ 230 mm2 K/W). The addition of carbon nanotube arrays did not alter the magnetic properties of the gadolinium foils and only a slight decrease in the magnetic moment of the gadolinium samples (8-13%) was measured after growth.

  18. Chemical reactions confined within carbon nanotubes.

    PubMed

    Miners, Scott A; Rance, Graham A; Khlobystov, Andrei N

    2016-08-22

    In this critical review, we survey the wide range of chemical reactions that have been confined within carbon nanotubes, particularly emphasising how the pairwise interactions between the catalysts, reactants, transition states and products of a particular molecular transformation with the host nanotube can be used to control the yields and distributions of products of chemical reactions. We demonstrate that nanoscale confinement within carbon nanotubes enables the control of catalyst activity, morphology and stability, influences the local concentration of reactants and products thus affecting equilibria, rates and selectivity, pre-arranges the reactants for desired reactions and alters the relative stability of isomeric products. We critically evaluate the relative advantages and disadvantages of the confinement of chemical reactions inside carbon nanotubes from a chemical perspective and describe how further developments in the controlled synthesis of carbon nanotubes and the incorporation of multifunctionality are essential for the development of this ever-expanding field, ultimately leading to the effective control of the pathways of chemical reactions through the rational design of multi-functional carbon nanoreactors.

  19. Different Technical Applications of Carbon Nanotubes.

    PubMed

    Abdalla, S; Al-Marzouki, F; Al-Ghamdi, Ahmed A; Abdel-Daiem, A

    2015-12-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. For commercial applications, large quantities and high purity of carbon nanotubes are needed. Different types of carbon nanotubes can be synthesized in various ways. The most common techniques currently practiced are arc discharge, laser ablation, and chemical vapor deposition and flame synthesis. The purification of CNTs is carried out using various techniques mainly oxidation, acid treatment, annealing, sonication, filtering chemical functionalization, etc. However, high-purity purification techniques still have to be developed. Real applications are still under development. This paper addresses the current research on the challenges that are associated with synthesis methods, purification methods, and dispersion and toxicity of CNTs within the scope of different engineering applications, energy, and environmental impact.

  20. Different Technical Applications of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Abdalla, S.; Al-Marzouki, F.; Al-Ghamdi, Ahmed A.; Abdel-Daiem, A.

    2015-09-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. For commercial applications, large quantities and high purity of carbon nanotubes are needed. Different types of carbon nanotubes can be synthesized in various ways. The most common techniques currently practiced are arc discharge, laser ablation, and chemical vapor deposition and flame synthesis. The purification of CNTs is carried out using various techniques mainly oxidation, acid treatment, annealing, sonication, filtering chemical functionalization, etc. However, high-purity purification techniques still have to be developed. Real applications are still under development. This paper addresses the current research on the challenges that are associated with synthesis methods, purification methods, and dispersion and toxicity of CNTs within the scope of different engineering applications, energy, and environmental impact.

  1. Different Technical Applications of Carbon Nanotubes.

    PubMed

    Abdalla, S; Al-Marzouki, F; Al-Ghamdi, Ahmed A; Abdel-Daiem, A

    2015-12-01

    Carbon nanotubes have been of great interest because of their simplicity and ease of synthesis. The novel properties of nanostructured carbon nanotubes such as high surface area, good stiffness, and resilience have been explored in many engineering applications. Research on carbon nanotubes have shown the application in the field of energy storage, hydrogen storage, electrochemical supercapacitor, field-emitting devices, transistors, nanoprobes and sensors, composite material, templates, etc. For commercial applications, large quantities and high purity of carbon nanotubes are needed. Different types of carbon nanotubes can be synthesized in various ways. The most common techniques currently practiced are arc discharge, laser ablation, and chemical vapor deposition and flame synthesis. The purification of CNTs is carried out using various techniques mainly oxidation, acid treatment, annealing, sonication, filtering chemical functionalization, etc. However, high-purity purification techniques still have to be developed. Real applications are still under development. This paper addresses the current research on the challenges that are associated with synthesis methods, purification methods, and dispersion and toxicity of CNTs within the scope of different engineering applications, energy, and environmental impact. PMID:26377211

  2. Measurement Challenges for Carbon Nanotube Material

    NASA Technical Reports Server (NTRS)

    Sosa, Edward; Arepalli, Sivaram; Nikolaev, Pasha; Gorelik, Olga; Yowell, Leonard

    2006-01-01

    The advances in large scale applications of carbon nanotubes demand a reliable supply of raw and processed materials. It is imperative to have a consistent quality control of these nanomaterials to distinguish material inconsistency from the modifications induced by processing of nanotubes for any application. NASA Johnson Space Center realized this need five years back and started a program to standardize the characterization methods. The JSC team conducted two workshops (2003 and 2005) in collaboration with NIST focusing on purity and dispersion measurement issues of carbon nanotubes [1]. In 2004, the NASA-JSC protocol was developed by combining analytical techniques of SEM, TEM, UV-VIS-NIR absorption, Raman, and TGA [2]. This protocol is routinely used by several researchers across the world as a first step in characterizing raw and purified carbon nanotubes. A suggested practice guide consisting of detailed chapters on TGA, Raman, electron microscopy and NIR absorption is in the final stages and is undergoing revisions with input from the nanotube community [3]. The possible addition of other techniques such as XPS, and ICP to the existing protocol will be presented. Recent activities at ANSI and ISO towards implementing these protocols as nanotube characterization standards will be discussed.

  3. Bulk Cutting of Carbon Nanotubes Using Electron Beam Irradiation

    NASA Technical Reports Server (NTRS)

    Ziegler, Kirk J. (Inventor); Rauwald, Urs (Inventor); Hauge, Robert H. (Inventor); Schmidt, Howard K. (Inventor); Smalley, Richard E. (Inventor); Kittrell, W. Carter (Inventor); Gu, Zhenning (Inventor)

    2013-01-01

    According to some embodiments, the present invention provides a method for attaining short carbon nanotubes utilizing electron beam irradiation, for example, of a carbon nanotube sample. The sample may be pretreated, for example by oxonation. The pretreatment may introduce defects to the sidewalls of the nanotubes. The method is shown to produces nanotubes with a distribution of lengths, with the majority of lengths shorter than 100 tun. Further, the median length of the nanotubes is between about 20 nm and about 100 nm.

  4. Determination of type A trichothecenes in coix seed by magnetic solid-phase extraction based on magnetic multi-walled carbon nanotubes coupled with ultra-high performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Dong, Maofeng; Si, Wenshuai; Wang, Weimin; Bai, Bing; Nie, Dongxia; Song, Weiguo; Zhao, Zhihui; Guo, Yirong; Han, Zheng

    2016-09-01

    Magnetic solid-phase extraction (m-SPE) is a promising sample preparation approach due to its convenience, speed, and simplicity. For the first time, a rapid and reliable m-SPE approach using magnetic multi-walled carbon nanotubes (m-MWCNTs) as the adsorbent was proposed for purification of type A trichothecenes including T-2 toxins (T2), HT-2 toxins (HT-2), diacetoxyscirpenol (DAS), and neosolaniol (NEO) in coix seed. The m-MWCNTs were synthesized by assembling the magnetic nanoparticles (Fe3O4) with MWCNTs by sonication through an aggregation wrap mechanism, and characterized by transmission electron microscope. Several key parameters affecting the performance of the procedure were extensively investigated including extraction solutions, desorption solvents, and m-MWCNT amounts. Under the optimal sample preparation conditions followed by analysis with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), high sensitivity (limit of quantification in the range of 0.3-1.5 μg kg(-1)), good linearity (R (2) > 0.99), satisfactory recovery (73.6-90.6 %), and acceptable precision (≤2.5 %) were obtained. The analytical performance of the developed method has also been successfully evaluated in real coix seed samples. Graphical Abstract Flow chart of determination of type A trichothecenes in coix seed by magnetic solid-phase extraction coupled with ultra-high performance liquid chromatography-tandem mass spectrometry.

  5. 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

  6. 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.

  7. 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.

  8. A comparative study on the lithium-ion storage performances of carbon nanotubes and tube-in-tube carbon nanotubes.

    PubMed

    Xu, Yi-Jun; Liu, Xi; Cui, Guanglei; Zhu, Bo; Weinberg, Gisela; Schlögl, Robert; Maier, Joachim; Su, Dang Sheng

    2010-03-22

    A comparative study of the electrochemical performances of carbon nanotubes and tube-in-tube carbon nanotubes reveals a dependence effect of lithium-ion storage behavior on the detailed nanostructure of carbon nanotubes. In particular, the impurity that graphitic particles or graphene fragments inherently present in carbon nanotubes plays a crucial role in the lithium-ion storage capacity of the carbon nanotubes. Compared to acid-washed carbon nanotubes, the assembly of graphitic impurity fragments in the tube-in-tube structures hinders lithium-ion diffusion, thus drastically decreasing the rate performance of lithium-ion storage. Significantly, our results indicate that the lithium-ion storage capacity of carbon nanotubes as anode electrodes can be improved or controlled by optimizing the microstructure composition of impurity graphitic nanoparticles or graphene fragments in the matrix of the carbon nanotubes.

  9. Formation of Carbon Nanotubes in a Microgravity Environment

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  10. Effects of single-walled carbon nanotubes on lysozyme gelation.

    PubMed

    Tardani, Franco; La Mesa, Camillo

    2014-09-01

    The possibility to disperse carbon nanotubes in biocompatible matrices has got substantial interest from the scientific community. Along this research line, the inclusion of single walled carbon nanotubes in lysozyme-based hydrogels was investigated. Experiments were performed at different nanotube/lysozyme weight ratios. Carbon nanotubes were dispersed in protein solutions, in conditions suitable for thermal gelation. The state of the dispersions was determined before and after thermal treatment. Rheology, dynamic light scattering and different microscopies investigated the effect that carbon nanotubes exert on gelation. The gelation kinetics and changes in gelation temperature were determined. The effect of carbon and lysozyme content on the gel properties was, therefore, determined. At fixed lysozyme content, moderate amounts of carbon nanotubes do not disturb the properties of hydrogel composites. At moderately high volume fractions in carbon nanotubes, the gels become continuous in both lysozyme and nanotubes. This is because percolating networks are presumably formed. Support to the above statements comes by rheology.

  11. Mechanics of Carbon Nanotubes and their Polymer Composites

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  12. Interaction of pristine and functionalized carbon nanotubes with lipid membranes.

    PubMed

    Baoukina, Svetlana; Monticelli, Luca; Tieleman, D Peter

    2013-10-10

    Carbon nanotubes are widely used in a growing number of applications. Their interactions with biological materials, cell membranes in particular, is of interest in applications including drug delivery and for understanding the toxicity of carbon nanotubes. We use extensive molecular dynamics simulations with the MARTINI model to study the interactions of model nanotubes of different thickness, length, and patterns of chemical modification with model membranes. In addition, we characterize the interactions of small bundles of carbon nanotubes with membrane models. Short pristine carbon nanotubes readily insert into membranes and adopt an orientation parallel to the plane of the membrane in the center of the membrane. Larger aggregates and functionalized nanotubes exhibit a range of possible interactions. The distribution and orientation of carbon nanotubes can be controlled by functionalizing the nanotubes. Free energy calculations provide thermodynamic insight into the preferred orientations of different nanotubes and quantify structural defects in the lipid matrix.

  13. Carbon nanotube suspensions, dispersions, & composites

    NASA Astrophysics Data System (ADS)

    Simmons, Trevor John

    Carbon Nanotubes (CNTs) are amazing structures that hold the potential to revolutionize many areas of scientific research. CNTs can be behave both as semiconductors and metals, can be grown in highly ordered arrays and patterns or in random orientation, and can be comprised of one graphene cylinder (single wall nanotube, SWNT) or several concentric graphene cylinders (multi-wall nanotube, MWNT). Although these structures are usually only a few nanometers wide, they can be grown up to centimeter lengths, and in massive quantities. CNTs can be produced in a variety of processes ranging from repeated combustion of organic material such as dried grass, arc-discharge with graphite electrodes, laser ablation of a graphitic target, to sophisticated chemical vapor deposition (CVD) techniques. CNTs are stronger than steel but lighter than aluminum, and can be more conductive than copper or semiconducting like silicon. This variety of properties has been matched by the wide variety of applications that have been developed for CNTs. Many of these applications have been limited by the inability of researchers to tame these structures, and incorporating CNTs into existing technologies can be exceedingly difficult and prohibitively expensive. It is therefore the aim of the current study to develop strategies for the solution processing and deposition of CNTs and CNT-composites, which will enable the use of CNTs in existing and emerging technologies. CNTs are not easily suspended in polar solvents and are extremely hydrophobic materials, which has limited much of the solution processing to organic solvents, which also cannot afford high quality dispersions of CNTs. The current study has developed a variety of aqueous CNT solutions that employ surfactants, water-soluble polymers, or both to create suspensions of CNTs. These CNT 'ink' solutions were deposited with a variety of techniques that have afforded many interesting structures, both randomly oriented as well as highly

  14. Graphene-carbon nanotube hybrid materials and use as electrodes

    DOEpatents

    Tour, James M.; Zhu, Yu; Li, Lei; Yan, Zheng; Lin, Jian

    2016-09-27

    Provided are methods of making graphene-carbon nanotube hybrid materials. Such methods generally include: (1) associating a graphene film with a substrate; (2) applying a catalyst and a carbon source to the graphene film; and (3) growing carbon nanotubes on the graphene film. The grown carbon nanotubes become covalently linked to the graphene film through carbon-carbon bonds that are located at one or more junctions between the carbon nanotubes and the graphene film. In addition, the grown carbon nanotubes are in ohmic contact with the graphene film through the carbon-carbon bonds at the one or more junctions. The one or more junctions may include seven-membered carbon rings. Also provided are the formed graphene-carbon nanotube hybrid materials.

  15. Selective microwave absorption of iron-rich carbon nanotube composites.

    PubMed

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

    2010-03-01

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

  16. Selective microwave absorption of iron-rich carbon nanotube composites.

    PubMed

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

    2010-03-01

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

  17. A review on protein functionalized carbon nanotubes.

    PubMed

    Nagaraju, Kathyayini; Reddy, Roopa; Reddy, Narendra

    2015-01-01

    Carbon nanotubes (CNTs) have been widely recognized and used for controlled drug delivery and in various other fields due to their unique properties and distinct advantages. Both single-walled carbon nanotubes (SWCNTs) and multiwalled (MWCNTs) carbon nanotubes are used and/or studied for potential applications in medical, energy, textile, composite, and other areas. Since CNTs are chemically inert and are insoluble in water or other organic solvents, they are functionalized or modified to carry payloads or interact with biological molecules. CNTs have been preferably functionalized with proteins because CNTs are predominantly used for medical applications such as delivery of drugs, DNA and genes, and also for biosensing. Extensive studies have been conducted to understand the interactions, cytotoxicity, and potential applications of protein functionalized CNTs but contradicting results have been published on the cytotoxicity of the functionalized CNTs. This paper provides a brief review of CNTs functionalized with proteins, methods used to functionalize the CNTs, and their potential applications. PMID:26660626

  18. Carbon nanotubes in neuroregeneration and repair.

    PubMed

    Fabbro, Alessandra; Prato, Maurizio; Ballerini, Laura

    2013-12-01

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

  19. A review on protein functionalized carbon nanotubes.

    PubMed

    Nagaraju, Kathyayini; Reddy, Roopa; Reddy, Narendra

    2015-12-18

    Carbon nanotubes (CNTs) have been widely recognized and used for controlled drug delivery and in various other fields due to their unique properties and distinct advantages. Both single-walled carbon nanotubes (SWCNTs) and multiwalled (MWCNTs) carbon nanotubes are used and/or studied for potential applications in medical, energy, textile, composite, and other areas. Since CNTs are chemically inert and are insoluble in water or other organic solvents, they are functionalized or modified to carry payloads or interact with biological molecules. CNTs have been preferably functionalized with proteins because CNTs are predominantly used for medical applications such as delivery of drugs, DNA and genes, and also for biosensing. Extensive studies have been conducted to understand the interactions, cytotoxicity, and potential applications of protein functionalized CNTs but contradicting results have been published on the cytotoxicity of the functionalized CNTs. This paper provides a brief review of CNTs functionalized with proteins, methods used to functionalize the CNTs, and their potential applications.

  20. Detection of gas atoms with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Arash, B.; Wang, Q.

    2013-05-01

    Owning to their unparalleled sensitivity resolution, nanomechanical resonators have excellent capabilities in design of nano-sensors for gas detection. The current challenge is to develop new designs of the resonators for differentiating distinct gas atoms with a recognizably high sensitivity. In this work, the characteristics of impulse wave propagation in carbon nanotube-based sensors are investigated using molecular dynamics simulations to provide a new method for detection of noble gases. A sensitivity index based on wave velocity shifts in a single-walled carbon nanotube, induced by surrounding gas atoms, is defined to explore the efficiency of the nano-sensor. The simulation results indicate that the nano-sensor is able to differentiate distinct noble gases at the same environmental temperature and pressure. The inertia and the strengthening effects by the gases on wave characteristics of carbon nanotubes are particularly discussed, and a continuum mechanics shell model is developed to interpret the effects.

  1. Boron-Filled Hybrid Carbon Nanotubes.

    PubMed

    Patel, Rajen B; Chou, Tsengming; Kanwal, Alokik; Apigo, David J; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-07-27

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs.

  2. Boron-Filled Hybrid Carbon Nanotubes

    PubMed Central

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-01-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs. PMID:27460526

  3. Boron-Filled Hybrid Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-07-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs.

  4. Refoldable Peptide Barrel -- Carbon Nanotube Junctions

    NASA Astrophysics Data System (ADS)

    Titov, Alexey; Wang, Boyang; Kral, Petr

    2008-03-01

    We design hybrid bio-nano-junctions formed by cylindrical peptide structures covalently attached to carbon nanotubes. The cylinders are composed of 5 pairs of antiparallel peptide strands that are ``one-to-one'' matched and covalently bonded through ester and amide bonds to the terminal C atoms in two (20,0) carbon nanotubes. The remaining terminal carbons in the CNTs are replaced by nitrogens, forming embedded quinoline-like structures. The used peptide strands are composed of charged amino acids that form cylindrical patterns with preferred stable configurations. By applying a torque to the nanotubes, we can reversibly fold and control the overall structure of the peptide barrels. The junctions might allow the collection and delivery of drugs and activation of biological molecules attached to them.

  5. Boron-Filled Hybrid Carbon Nanotubes.

    PubMed

    Patel, Rajen B; Chou, Tsengming; Kanwal, Alokik; Apigo, David J; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-01-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs. PMID:27460526

  6. Carbon Nanotubes Synthesis Through Gamma Radiation

    NASA Astrophysics Data System (ADS)

    Tirado, Pablo; Garcia, Rafael; Montes, Jorge; Melendrez, Rodrigo; Barboza, Marcelino; Contreras, Oscar

    2015-03-01

    Carbon nanotubes show a great potential of applications since there discovery by Iijima in 1991[1] due to their numerous physical-chemical properties such as their high weight to strength relationship, which make them ideal to use in high resistance compound materials, and in many other applications[2] In this work, a novel method for the synthesis of carbon nanotubes is presented, starting from an ultra-thin sheet of graphite synthesized by the chemical vapor decomposition technique (CVD), using ultra high purity methane and hydrogen at 1200°C in a horizontal quartz reactor. For the synthesis of carbon nanotubes, the graphite sheets were exposed to different doses of radiation, with the objective of breaking the graphite bonds and form carbon nanotubes; a Gammacell equipment model 220 Excel was used for the purpose, which counts with a radiation source of cobalt 60, and a current radiation rate of 0.9 Gy/seconds. The time of exposure to radiation was varied in each sample, according to the desired dose of radiation in each case, afterwards the samples were characterized using the Raman spectroscopy and TEM microscopy techniques with the objective of observing the kind of nanotubes formed, their morphology and their number of defects. Results will be shown during the poster session.

  7. 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.

  8. 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

  9. Lipid nanoscaffolds in carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  10. Carbon nanotubes as actuators in smart structures

    NASA Astrophysics Data System (ADS)

    Monner, Hans P.; Muehle, Stefan; Wierach, Peter

    2003-08-01

    Carbon Nanotubes have diameters in nanometer scale, are up to tens of microns long and can be single- or multi-walled (SWNT and MWNT). Compared with carbon fibers, which typically have a Young's modulus of up to 750 GPa, the elastic modulus of Carbon Nanotubes has been measured to be approximately 1-2 TPa. The strength of Carbon Nanotubes has been reported to be about two order of magnitude higher than current high strength carbon fibers. Additionally especially SWNT show excellent actuator behaviour. Electromechanical actuators based on sheets of SWNT show to generate higher stress than natural muscles and higher strains than ferroelectrics like PZT. Unlike conventional ferroelectric actuators, low operating voltages of a few volts generate large actuator strains. Thus, this paper will give a brief overview of the current activities within this field and show some recent results of the Carbon Nanotube actuator development at the DLR-Institute of Structural Mechanic suggesting that optimized SWNT sheets may eventually provide substantially higher work densities per cycle than any previously known material.

  11. Comparison between magnetic and non magnetic multi-walled carbon nanotubes-dispersive solid-phase extraction combined with ultra-high performance liquid chromatography for the determination of sulfonamide antibiotics in water samples.

    PubMed

    Herrera-Herrera, Antonio V; Hernández-Borges, Javier; Afonso, María M; Palenzuela, J Antonio; Rodríguez-Delgado, Miguel Ángel

    2013-11-15

    In this manuscript, a new method based on the use of off-line dispersive solid-phase extraction (dSPE) combined with ultra-high performance liquid chromatography with diode-array detection was developed to determine 11 sulfonamide antibiotics (sulfanilamide, sulfacetamide, sulfadiazine, sulfathiazole, sulfamerazine, sulfadimidin, sulfamethoxypyridazine, sulfadoxine, sulfamethoxazole, sulfisoxazole and sulfadimethoxine) in mineral waters with different mineral content. For this purpose, pristine multi-walled carbon nanotubes (MWCNTs) and magnetic-MWCNTs (m-MWCNTs) were used as sorbents. Magnetic nanoparticles were synthesized by means of a solvothermal process, assembled onto CNTs through an "aggregation wrap" mechanism and characterized by scanning electron microscopy. Parameters affecting the extraction such as volume and pH of the sample, amount of sorbent and type and volume of eluent were optimized. Once optimum extraction conditions (250 mL of water at pH 6.0 and elution with 25 mL of MeOH) were obtained, the extraction efficiency of the different carbon nanomaterials was compared. Results demonstrated the higher extraction capacity of pristine MWCNTs with recoveries between 61 and 110% (except for sulfacetamide which ranged between 40 and 53%) and between 22 and 77% for m-MWCNTs. Limits of detection lower than 32 ng/L were achieved for all of the analyzed samples.

  12. Ultralight multiwalled carbon nanotube aerogel.

    PubMed

    Zou, Jianhua; Liu, Jianhua; Karakoti, Ajay Singh; Kumar, Amit; Joung, Daeha; Li, Qiang; Khondaker, Saiful I; Seal, Sudipta; Zhai, Lei

    2010-12-28

    Ultralight multiwalled carbon nanotube (MWCNT) aerogel is fabricated from a wet gel of well-dispersed pristine MWCNTs. On the basis of a theoretical prediction that increasing interaction potential between CNTs lowers their critical concentration to form an infinite percolation network, poly(3-(trimethoxysilyl) propyl methacrylate) (PTMSPMA) is used to disperse and functionalize MWCNTs where the subsequent hydrolysis and condensation of PTMSPMA introduces strong and permanent chemical bonding between MWCNTs. The interaction is both experimentally and theoretically proven to facilitate the formation of a MWCNT percolation network, which leads to the gelation of MWCNT dispersion at ultralow MWCNT concentration. After removing the liquid component from the MWCNT wet gel, the lightest ever free-standing MWCNT aerogel monolith with a density of 4 mg/cm(3) is obtained. The MWCNT aerogel has an ordered macroporous honeycomb structure with straight and parallel voids in 50-150 μm separated by less than 100 nm thick walls. The entangled MWCNTs generate mesoporous structures on the honeycomb walls, creating aerogels with a surface area of 580 m(2)/g which is much higher than that of pristine MWCNTs (241 m(2)/g). Despite the ultralow density, the MWCNT aerogels have an excellent compression recoverable property as demonstrated by the compression test. The aerogels have an electrical conductivity of 3.2 × 10(-2) S·cm(-1) that can be further increased to 0.67 S·cm(-1) by a high-current pulse method without degrading their structures. The excellent compression recoverable property, hierarchically porous structure with large surface area, and high conductivity grant the MWCNT aerogels exceptional pressure and chemical vapor sensing capabilities. PMID:21090673

  13. A carbon nanotube optical rectenna

    NASA Astrophysics Data System (ADS)

    Sharma, Asha; Singh, Virendra; Bougher, Thomas L.; Cola, Baratunde A.

    2015-12-01

    An optical rectenna—a device that directly converts free-propagating electromagnetic waves at optical frequencies to direct current—was first proposed over 40 years ago, yet this concept has not been demonstrated experimentally due to fabrication challenges at the nanoscale. Realizing an optical rectenna requires that an antenna be coupled to a diode that operates on the order of 1 PHz (switching speed on the order of 1 fs). Diodes operating at these frequencies are feasible if their capacitance is on the order of a few attofarads, but they remain extremely difficult to fabricate and to reliably couple to a nanoscale antenna. Here we demonstrate an optical rectenna by engineering metal-insulator-metal tunnel diodes, with a junction capacitance of ˜2 aF, at the tip of vertically aligned multiwalled carbon nanotubes (˜10 nm in diameter), which act as the antenna. Upon irradiation with visible and infrared light, we measure a d.c. open-circuit voltage and a short-circuit current that appear to be due to a rectification process (we account for a very small but quantifiable contribution from thermal effects). In contrast to recent reports of photodetection based on hot electron decay in a plasmonic nanoscale antenna, a coherent optical antenna field appears to be rectified directly in our devices, consistent with rectenna theory. Finally, power rectification is observed under simulated solar illumination, and there is no detectable change in diode performance after numerous current-voltage scans between 5 and 77 °C, indicating a potential for robust operation.

  14. A tunable carbon nanotube electromechanical oscillator

    NASA Astrophysics Data System (ADS)

    Sazonova, Vera; Yaish, Yuval; Üstünel, Hande; Roundy, David; Arias, Tomás A.; McEuen, Paul L.

    2004-09-01

    Nanoelectromechanical systems (NEMS) hold promise for a number of scientific and technological applications. In particular, NEMS oscillators have been proposed for use in ultrasensitive mass detection, radio-frequency signal processing, and as a model system for exploring quantum phenomena in macroscopic systems. Perhaps the ultimate material for these applications is a carbon nanotube. They are the stiffest material known, have low density, ultrasmall cross-sections and can be defect-free. Equally important, a nanotube can act as a transistor and thus may be able to sense its own motion. In spite of this great promise, a room-temperature, self-detecting nanotube oscillator has not been realized, although some progress has been made. Here we report the electrical actuation and detection of the guitar-string-like oscillation modes of doubly clamped nanotube oscillators. We show that the resonance frequency can be widely tuned and that the devices can be used to transduce very small forces.

  15. Laser ablative synthesis of carbon nanotubes

    DOEpatents

    Smith, Michael W.; Jordan, Kevin; Park, Cheol

    2010-03-02

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

  16. 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.

  17. Computational Nanomechanics of Carbon Nanotubes and Composites

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Wei, Chenyu; Cho, Kyeongjae; Biegel, Bryan (Technical Monitor)

    2002-01-01

    Nanomechanics of individual carbon and boron-nitride nanotubes and their application as reinforcing fibers in polymer composites has been reviewed with interplay of theoretical modeling, computer simulations and experimental observations. The emphasis in this work is on elucidating the multi-length scales of the problems involved, and of different simulation techniques that are needed to address specific characteristics of individual nanotubes and nanotube polymer-matrix interfaces. Classical molecular dynamics simulations are shown to be sufficient to describe the generic behavior such as strength and stiffness modulus but are inadequate to describe elastic limit and nature of plastic buckling at large strength. Quantum molecular dynamics simulations are shown to bring out explicit atomic nature dependent behavior of these nanoscale materials objects that are not accessible either via continuum mechanics based descriptions or through classical molecular dynamics based simulations. As examples, we discus local plastic collapse of carbon nanotubes under axial compression and anisotropic plastic buckling of boron-nitride nanotubes. Dependence of the yield strain on the strain rate is addressed through temperature dependent simulations, a transition-state-theory based model of the strain as a function of strain rate and simulation temperature is presented, and in all cases extensive comparisons are made with experimental observations. Mechanical properties of nanotube-polymer composite materials are simulated with diverse nanotube-polymer interface structures (with van der Waals interaction). The atomistic mechanisms of the interface toughening for optimal load transfer through recycling, high-thermal expansion and diffusion coefficient composite formation above glass transition temperature, and enhancement of Young's modulus on addition of nanotubes to polymer are discussed and compared with experimental observations.

  18. The Use of Plasma Vortexes in Creating Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Leith, Alexander; Alexander Leith Collaboration

    2016-03-01

    Carbon nanotubes have been created in a variety of ways such as arc discharge, laser ablation, and chemical vapor deposition (CVD). Each of these techniques has been proven to produce carbon nanotubes in small quantities in a lab setting. This is the problem that we have been addressing. Over the course of 16 months, we have been working on a new method of carbon nanotube production that is based around fluid dynamics and plasma. We have created the basic components to test this new way to produce carbon nanotubes. This research will ideally provide a new avenue for carbon nanotube production. Worked with Dr. Randal Tagg of the University of Colorado Denver.

  19. Titania carbon nanotube composites for enhanced photocatalysis

    NASA Astrophysics Data System (ADS)

    Pyrgiotakis, Georgios

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

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

    SciTech Connect

    Kong, Lirong; Lu Xiaofeng; Zhang Wanjin

    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.

  1. Exciton-Polariton Dynamics in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Bondarev, Igor

    2007-03-01

    This work addresses theoretically the nonlinear response of phonon-coupled excitons[1] in carbon nanotubes to an external electromagnetic field. The photon Green's function approach developed recently to quantize the electromagnetic field in the presence of quasi-1D absorbing bodies[2],[3] is being used to study the dynamics of phonon-coupled excitonic states interacting with the surface photonic modes excited by the external electromagnetic field in semiconductor carbon nanotubes. The formation of the new elementary excitations, exciton-polaritons, representing the eigen states of the full photon-matter Hamiltonian has been studied for small-diameter nanotubes under strong exciton-photon coupling. Time-resolved simulations have been performed of the coherent exciton- polariton dynamics with the exciton-phonon interactions taken into account. The criteria for the coherent control of the excitonic states population in optically excited carbon nanotubes have been formulated. [1]F.Plentz et al, Phys. Rev. Lett. 95, 247401 (2005). [2]I.V.Bondarev and Ph.Lambin, Phys. Rev. B 72, 035451 (2005). [3]I.V.Bondarev and Ph.Lambin, in: Trends in Nanotubes Reasearch (NovaScience, New York, 2006), p.139.

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

    PubMed

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

    2013-01-01

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

  3. 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.

  4. Improved Method of Purifying Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D.

    2004-01-01

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

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

    SciTech Connect

    2010-03-01

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

  6. A novel redox-sensitive system based on single-walled carbon nanotubes for chemo-photothermal therapy and magnetic resonance imaging

    PubMed Central

    Hou, Lin; Yang, Xiaomin; Ren, Junxiao; Wang, Yongchao; Zhang, Huijuan; Feng, Qianhua; Shi, Yuyang; Shan, Xiaoning; Yuan, Yujie; Zhang, Zhenzhong

    2016-01-01

    Recently, nanomaterials with multiple functions, such as drug carrier, magnetic resonance imaging (MRI) and optical imaging, and photothermal therapy, have become more and more popular in cancer research. In this work, a novel redox-sensitive system constructed from hyaluronic acid (HA), single-walled carbon nanotubes (SWCNTs), doxorubicin (DOX), and gadolinium (Gd) was successfully developed. Herein, HA-modified SWCNTs (SWCNTs-HA) was first synthesized, and then DOX was conjugated with HA by disulfide bond (SWCNTs-HA-ss-DOX). Finally, MRI contrast agents, Gd3+-ion loading occurred through the sidewall defects of SWCNTs, whose cytotoxicity could be sequestered within the SWCNTs. In vitro release of DOX showed that this system accomplished much faster drug release under reducing condition. Confocal microscopy analysis confirmed that Gd/SWCNTs-HA-ss-DOX were capable of simultaneously delivering DOX and SWCNTs into Michigan Cancer Foundation-7 cells via HA receptor-mediated endocytosis followed by rapid transport of cargoes into the cytosol. Enhanced cytotoxicity of Gd/SWCNTs-HA-ss-DOX further proved that the sensitive system was more potent for intracellular drug delivery as compared with the insensitive control. Meanwhile, tumor cell killing potency was improved when Gd/SWCNTs-HA-ss-DOX were combined with near-infrared irradiation, with IC50 of 0.61 µg/mL at 48 hours. In vivo investigation demonstrated that Gd/SWCNTs-HA-ss-DOX could effectively accumulate in tumor sites and possessed the greatest synergistic antitumor efficacy, especially under the 808 nm laser irradiation. More importantly, this system could be used as a contrast agent for MRI to identify the location and extent of tumor tissues. These results suggested that Gd/SWCNTs-HA-ss-DOX might be a promising system for targeting chemo-photothermal therapy and MRI diagnosis in future clinical anticancer applications. PMID:26917960

  7. A novel redox-sensitive system based on single-walled carbon nanotubes for chemo-photothermal therapy and magnetic resonance imaging.

    PubMed

    Hou, Lin; Yang, Xiaomin; Ren, Junxiao; Wang, Yongchao; Zhang, Huijuan; Feng, Qianhua; Shi, Yuyang; Shan, Xiaoning; Yuan, Yujie; Zhang, Zhenzhong

    2016-01-01

    Recently, nanomaterials with multiple functions, such as drug carrier, magnetic resonance imaging (MRI) and optical imaging, and photothermal therapy, have become more and more popular in cancer research. In this work, a novel redox-sensitive system constructed from hyaluronic acid (HA), single-walled carbon nanotubes (SWCNTs), doxorubicin (DOX), and gadolinium (Gd) was successfully developed. Herein, HA-modified SWCNTs (SWCNTs-HA) was first synthesized, and then DOX was conjugated with HA by disulfide bond (SWCNTs-HA-ss-DOX). Finally, MRI contrast agents, Gd(3+)-ion loading occurred through the sidewall defects of SWCNTs, whose cytotoxicity could be sequestered within the SWCNTs. In vitro release of DOX showed that this system accomplished much faster drug release under reducing condition. Confocal microscopy analysis confirmed that Gd/SWCNTs-HA-ss-DOX were capable of simultaneously delivering DOX and SWCNTs into Michigan Cancer Foundation-7 cells via HA receptor-mediated endocytosis followed by rapid transport of cargoes into the cytosol. Enhanced cytotoxicity of Gd/SWCNTs-HA-ss-DOX further proved that the sensitive system was more potent for intracellular drug delivery as compared with the insensitive control. Meanwhile, tumor cell killing potency was improved when Gd/SWCNTs-HA-ss-DOX were combined with near-infrared irradiation, with IC50 of 0.61 µg/mL at 48 hours. In vivo investigation demonstrated that Gd/SWCNTs-HA-ss-DOX could effectively accumulate in tumor sites and possessed the greatest synergistic antitumor efficacy, especially under the 808 nm laser irradiation. More importantly, this system could be used as a contrast agent for MRI to identify the location and extent of tumor tissues. These results suggested that Gd/SWCNTs-HA-ss-DOX might be a promising system for targeting chemo-photothermal therapy and MRI diagnosis in future clinical anticancer applications. PMID:26917960

  8. A novel redox-sensitive system based on single-walled carbon nanotubes for chemo-photothermal therapy and magnetic resonance imaging.

    PubMed

    Hou, Lin; Yang, Xiaomin; Ren, Junxiao; Wang, Yongchao; Zhang, Huijuan; Feng, Qianhua; Shi, Yuyang; Shan, Xiaoning; Yuan, Yujie; Zhang, Zhenzhong

    2016-01-01

    Recently, nanomaterials with multiple functions, such as drug carrier, magnetic resonance imaging (MRI) and optical imaging, and photothermal therapy, have become more and more popular in cancer research. In this work, a novel redox-sensitive system constructed from hyaluronic acid (HA), single-walled carbon nanotubes (SWCNTs), doxorubicin (DOX), and gadolinium (Gd) was successfully developed. Herein, HA-modified SWCNTs (SWCNTs-HA) was first synthesized, and then DOX was conjugated with HA by disulfide bond (SWCNTs-HA-ss-DOX). Finally, MRI contrast agents, Gd(3+)-ion loading occurred through the sidewall defects of SWCNTs, whose cytotoxicity could be sequestered within the SWCNTs. In vitro release of DOX showed that this system accomplished much faster drug release under reducing condition. Confocal microscopy analysis confirmed that Gd/SWCNTs-HA-ss-DOX were capable of simultaneously delivering DOX and SWCNTs into Michigan Cancer Foundation-7 cells via HA receptor-mediated endocytosis followed by rapid transport of cargoes into the cytosol. Enhanced cytotoxicity of Gd/SWCNTs-HA-ss-DOX further proved that the sensitive system was more potent for intracellular drug delivery as compared with the insensitive control. Meanwhile, tumor cell killing potency was improved when Gd/SWCNTs-HA-ss-DOX were combined with near-infrared irradiation, with IC50 of 0.61 µg/mL at 48 hours. In vivo investigation demonstrated that Gd/SWCNTs-HA-ss-DOX could effectively accumulate in tumor sites and possessed the greatest synergistic antitumor efficacy, especially under the 808 nm laser irradiation. More importantly, this system could be used as a contrast agent for MRI to identify the location and extent of tumor tissues. These results suggested that Gd/SWCNTs-HA-ss-DOX might be a promising system for targeting chemo-photothermal therapy and MRI diagnosis in future clinical anticancer applications.

  9. Coupling of carbon and peptide nanotubes.

    PubMed

    Montenegro, Javier; Vázquez-Vázquez, Carlos; Kalinin, Arseny; Geckeler, Kurt E; Granja, Juan R

    2014-02-12

    Two of the main types of nanotubular architectures are the single-walled carbon nanotubes (SWCNTs) and the self-assembling cyclic peptide nanotubes (SCPNs). We here report the preparation of the dual composite resulting from the ordered combination of both tubular motifs. In the resulting architecture, the SWCNTs can act as templates for the assembly of SCPNs that engage the carbon nanotubes noncovalently via pyrene "paddles", each member of the resulting hybrid stabilizing the other in aqueous solution. The particular hybrids obtained in the present study formed highly ordered oriented arrays and display complementary properties such as electrical conductivity. Furthermore, a self-sorting of the cyclic peptides toward semiconducting rather than metallic SWCNTs is also observed in the aqueous dispersions. It is envisaged that a broad range of exploitable properties may be achieved and/or controlled by varying the cyclic peptide components of similar SWCNT/SCPN hybrids.

  10. Exciton Hierarchies in Gapped Carbon Nanotubes

    SciTech Connect

    Konik, R.M.

    2011-04-01

    We present evidence that the strong electron-electron (e-e) interactions in gapped carbon nanotubes lead to finite hierarchies of excitons within a given nanotube subband. We study these hierarchies by employing a field theoretic reduction of the gapped carbon nanotube permitting e-e interactions to be treated exactly. We analyze this reduction by employing a Wilsonian-like numerical renormalization group. We are so able to determine the gap ratios of the one-photon excitons as a function of the effective strength of interactions. We also determine within the same subband the gaps of the two-photon excitons, the single particle gaps, as well as a subset of the dark excitons. The strong e-e interactions in addition lead to strongly renormalized dispersion relations where the consequences of spin-charge separation can be readily observed.

  11. Exciton hierarchies in gapped carbon nanotubes.

    PubMed

    Konik, Robert M

    2011-04-01

    We present evidence that the strong electron-electron (e-e) interactions in gapped carbon nanotubes lead to finite hierarchies of excitons within a given nanotube subband. We study these hierarchies by employing a field theoretic reduction of the gapped carbon nanotube permitting e-e interactions to be treated exactly. We analyze this reduction by employing a Wilsonian-like numerical renormalization group. We are so able to determine the gap ratios of the one-photon excitons as a function of the effective strength of interactions. We also determine within the same subband the gaps of the two-photon excitons, the single particle gaps, as well as a subset of the dark excitons. The strong e-e interactions in addition lead to strongly renormalized dispersion relations where the consequences of spin-charge separation can be readily observed.

  12. High Performance Multifunctional Carbon Nanotube Fibers

    NASA Astrophysics Data System (ADS)

    Dalton, Alan; Collins, Steve; Munoz, Edgar; Razal, Joselito; Ebron, Von; Ferraris, John; Baughman, Ray

    2003-03-01

    Exploiting the extraordinary properties of carbon nanotubes has remained somewhat elusive due to the inability to process the as produced insoluble soot into functional macroscopic assemblies. To this end we have developed a simple but effective method to produce continuous, homogeneous fibers containing carbon nanotubes having as-spun mechanical properties that compare very favorably to recognized synthetic and natural "super fibers" such as Kevlar and spider silk. By using novel spinning apparatus, spinning solutions, and spinning coagulants, we have spun nanotube fibers having record lengths, record tensile strengths, and having an energy-to-break (toughness) higher than any material that we have found. As an example of the potential multi-functionalities of our fibers, we have fabricated fiber supercapacitors, which we weave into textiles.

  13. Sodium insertion/extraction from single-walled and multi-walled carbon nanotubes: The differences and similarities

    NASA Astrophysics Data System (ADS)

    Goonetilleke, Damian; Pramudita, James C.; Choucair, Mohammad; Rawal, Aditya; Sharma, Neeraj

    2016-05-01

    A comparative study on the sodium-ion insertion and extraction of commercially-available multi-wall and single-wall carbon nanotubes is reported. Single-wall carbon nanotubes exhibit charge/discharge capacities of 126 mA h g-1 and multi-wall carbon nanotubes produce a lower capacity of 28 mA h g-1 after 50 cycles at 25 mA g-1. To understand these differences, a combination of X-ray diffraction and solid state nuclear magnetic resonance measurements were performed at various states of sodium insertion and extraction.23Na nuclear magnetic resonance studies, a technique previously rarely used for characterising electrodes from sodium-ion batteries, shows differences in the sodium chemical environment near multi-wall compared to single-wall carbon nanotubes with distinct sodium sites found to be active during sodium insertion and extraction for the carbon nanotubes. Both types of carbon nanotubes show a similar amount of reversible sodium available for insertion/extraction reactions, but multi-wall carbon nanotubes feature half the initial insertion capacity relative to single-wall carbon nanotubes. The electrochemical performance of the carbon nanotube electrodes are discussed in relation to the observed mechanism of sodium insertion.

  14. 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...

  15. Deconvoluting hepatic processing of carbon nanotubes

    PubMed Central

    Alidori, Simone; Bowman, Robert L.; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J. Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L. J.; Ulmert, Hans David S.; Brea, Elliott J.; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A.; McDevitt, Michael R.

    2016-01-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans. PMID:27468684

  16. Deconvoluting hepatic processing of carbon nanotubes.

    PubMed

    Alidori, Simone; Bowman, Robert L; Yarilin, Dmitry; Romin, Yevgeniy; Barlas, Afsar; Mulvey, J Justin; Fujisawa, Sho; Xu, Ke; Ruggiero, Alessandro; Riabov, Vladimir; Thorek, Daniel L J; Ulmert, Hans David S; Brea, Elliott J; Behling, Katja; Kzhyshkowska, Julia; Manova-Todorova, Katia; Scheinberg, David A; McDevitt, Michael R

    2016-01-01

    Single-wall carbon nanotubes present unique opportunities for drug delivery, but have not advanced into the clinic. Differential nanotube accretion and clearance from critical organs have been observed, but the mechanism not fully elucidated. The liver has a complex cellular composition that regulates a range of metabolic functions and coincidently accumulates most particulate drugs. Here we provide the unexpected details of hepatic processing of covalently functionalized nanotubes including receptor-mediated endocytosis, cellular trafficking and biliary elimination. Ammonium-functionalized fibrillar nanocarbon is found to preferentially localize in the fenestrated sinusoidal endothelium of the liver but not resident macrophages. Stabilin receptors mediate the endocytic clearance of nanotubes. Biocompatibility is evidenced by the absence of cell death and no immune cell infiltration. Towards clinical application of this platform, nanotubes were evaluated for the first time in non-human primates. The pharmacologic profile in cynomolgus monkeys is equivalent to what was reported in mice and suggests that nanotubes should behave similarly in humans. PMID:27468684

  17. Probing Photosensitization by Functionalized Carbon Nanotubes.

    PubMed

    Chen, Chia-Ying; Zepp, Richard G

    2015-12-01

    Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that may damage organisms by biomembrane oxidation or mediate environmental transformations of CNTs. Photosensitization by derivatized carbon nanotubes from various synthetic methods, and thus with different intrinsic characteristics (e.g., diameter and electronic properties), has been investigated under environmentally relevant aquatic conditions. We used the CNT-sensitized photoisomerization of sorbic acid ((2E,4E)-hexa-2,4-dienoic acid) and singlet oxygen formation to quantify the triplet states ((3)CNT*) formed upon irradiation of selected single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs). The CNTs used in our studies were derivatized by carboxyl groups to facilitate their dispersion in water. Results indicate that high-defect-density (thus well-stabilized), small-diameter, and semiconducting-rich CNTs have higher-measured excited triplet state formation and therefore singlet oxygen ((1)O2) yield. Derivatized SWCNTs were significantly more photoreactive than derivatized MWCNTs. Moreover, addition of sodium chloride resulted in increased aggregation and small increases in (1)O2 production of CNTs. The most photoreactive CNTs exhibited comparable photoreactivity (in terms of (3)CNT* formation and (1)O2 yield) to reference natural organic matter (NOM) under sunlight irradiation with the same mass-based concentration. Selected reference NOM could therefore be useful in evaluating environmental photoreactivity or intended antibacterial applications of CNTs.

  18. Chemistry of Carbon Nanotubes for Everyone

    ERIC Educational Resources Information Center

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

    2012-01-01

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

  19. In-line manufacture of carbon nanotubes

    DOEpatents

    Brambilla, Nicol Michele; Signorelli, Riccardo; Martini, Fabrizio; Corripio Luna, Oscar Enrique

    2015-04-28

    Mass production of carbon nanotubes (CNT) are facilitated by methods and apparatus disclosed herein. Advantageously, the methods and apparatus make use of a single production unit, and therefore provide for uninterrupted progress in a fabrication process. Embodiments of control systems for a variety of CNT production apparatus are included.

  20. Multiwall carbon nanotubes reinforced epoxy nanocomposites

    NASA Astrophysics Data System (ADS)

    Chen, Wei

    The emergence of carbon nanotubes (CNTs) has led to myriad possibilities for structural polymer composites with superior specific modulus, strength, and toughness. While the research activities in carbon nanotube reinforced polymer composites (NRPs) have made enormous progress towards fabricating next-generation advanced structural materials with added thermal, optical, and electrical advantages, questions concerning the filler dispersion, interface, and CNT alignment in these composites remain partially addressed. In this dissertation, the key technical challenges related to the synthesis, processing, and reinforcing mechanics governing the effective mechanical properties of NRPs were introduced and reviewed in the first two chapters. Subsequently, issues on the dispersion, interface control, hierarchical structure, and multi-functionality of NRPs were addressed based on functionalized multi-walled carbon nanotube reinforced DGEBA epoxy systems (NREs). In chapter 3, NREs with enhanced flexural properties were discussed in the context of improved dispersion and in-situ formation of covalent bonds at the interface. In chapter 4, NREs with controlled interface and tailored thermomechanical properties were demonstrated through the judicious choice of surface functionality and resin chemistry. In chapter 5, processing-condition-induced CNT organization in hierarchical epoxy nanocomposites was analyzed. In Chapter 6, possibilities were explored for multi-functional NREs for underwater acoustic structural applications. Finally, the findings of this dissertation were concluded and future research was proposed for ordered carbon nanotube array reinforced nanocomposites in the last chapter. Four journal publications resulted from this work are listed in Appendix.

  1. Heat Transport in Liquid Polyester Resin with Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Vales-Pinzón, C.; Quiñones-Weiss, G.; Alvarado-Gil, J. J.; Medina-Esquivel, R. A.

    2015-11-01

    Carbon nanotubes represent one of the most important materials in nanoscience and nanotechnology, due to their outstanding structural, mechanical, electrical, and thermal properties. It has been shown that when incorporated in a polymeric matrix, carbon nanotubes can improve its physical properties. In this work, thermal-diffusivity measurements of composite materials, prepared by mixing carbon nanotubes in liquid polyester resin, were performed by means of the thermal-wave resonant cavity. The results show an increase of the thermal diffusivity when the volume fraction of carbon nanotubes grows. It is also shown that this increase depends strongly on the diameter of the nanotubes.

  2. Exploring the Immunotoxicity of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Yu, Yanmei; Zhang, Qiu; Mu, Qingxin; Zhang, Bin; Yan, Bing

    2008-08-01

    Mass production of carbon nanotubes (CNTs) and their applications in nanomedicine lead to the increased exposure risk of nanomaterials to human beings. Although reports on toxicity of nanomaterials are rapidly growing, there is still a lack of knowledge on the potential toxicity of such materials to immune systems. This article reviews some existing studies assessing carbon nanotubes’ toxicity to immune system and provides the potential mechanistic explanation.

  3. Pure carbon nanoscale devices: Nanotube heterojunctions

    SciTech Connect

    Chico, L.; Crespi, V.H.; Benedict, L.X.; Louie, S.G.; Cohen, M.L. |

    1996-02-01

    Introduction of pentagon-heptagon pair defects into the hexagonal network of a single carbon nanotube can change the helicity of the tube and alter its electronic structure. Using a tight-binding method to calculate the electronic structure of such systems we show that they behave as nanoscale metal/semiconductor or semiconductor/semiconductor junctions. These junctions could be the building blocks of nanoscale electronic devices made entirely of carbon. {copyright} {ital 1996 The American Physical Society.}

  4. Purification Procedures for Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  5. Atomic nanotube welders: boron interstitials triggering connections in double-walled carbon nanotubes.

    PubMed

    Endo, Morinobu; Muramatsu, Hiroyuki; Hayashi, Takuya; Kim, Yoong-Ahm; Van Lier, Gregory; Charlier, Jean-Christophe; Terrones, Humberto; Terrones, Mauricio; Dresselhaus, Mildred S

    2005-06-01

    Here we demonstrate that the incorporation of boron (B) atoms between double-walled carbon nanotubes (DWNTs) during thermal annealing (1400-1600 degrees C) results in covalent nanotube "Y" junctions, DWNT coalescence, and the formation of flattened multiwalled carbon nanotubes (MWNTs). These processes occur via the merging of adjacent tubes, which is triggered by B interstitial atoms. We observe that B atom interstitials between DWNTs are responsible for the rapid establishment of covalent connections between neighboring tubes (polymerization), thereby resulting in the fast annealing of the carbon cylinders with B atoms embedded in the newly created carbon nanotube network. Once B is in the lattice, tube faceting (polygonization) starts to occur, and the electronic properties are expected to change dramatically. Therefore, B atoms indeed act as atomic nanotube fusers (or welders), and this process could now be used in assembling novel electronic nanotube devices, nanotube networks, carbon nanofoams and heterojunctions exhibiting p-type electronic properties.

  6. 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

  7. Carbon nanotubes on a spider silk scaffold.

    PubMed

    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.

  8. Carbon nanotubes on a spider silk scaffold

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

  9. Transmission Through Carbon Nanotubes with Polyhedral Caps

    NASA Technical Reports Server (NTRS)

    Anantram, M. P.; Govindan, T. R.

    1999-01-01

    We study electron transport between capped carbon nanotubes and a substrate, and relate this transport to the local density of states in the cap. Our results show that that the transmission probability mimics the behavior of the density of states at all energies except those that correspond to localized states. For a capped carbon nanotube that is not connected to a substrate, the localized states do not couple to the coexisting continuum states. However, close proximity of a substrate causes hybridization between these states. As a result, new transmission paths open from substrate states to nanotube continuum states via the localized states in the cap. We show that the interference between various paths gives rise to transmission antiresonances with the minimum equal to zero at the energy of the localized state. The presence of defects in the tube places close to the cap transforms antiresonances into resonances. Depending on the spatial position of defects, these resonant states are capable of carrying a large current. The results of this paper are of relevance to carbon nanotube based studies on molecular electronics and probe tip applications.

  10. Functionalization of vertically aligned carbon nanotubes

    PubMed Central

    Snyders, Rony; Colomer, Jean-François

    2013-01-01

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

  11. Fabrication and field emission properties of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Peng

    Research on the area of the fabrication of carbon nanotubes is fundamental and critical to the entire subject of carbon nanotubes. This dissertation describes an experiment to fabricate carbon nanotubes by the method of Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD) and the electron field emission properties of carbon nanotubes. A MPECVD system was built and used to fabricate the vertical aligned carbon nanotube film. Scanning electron microscope (SEM), Raman spectroscopy and transmission electron microscopy (TEM) were used to characterize the as-grown carbon nanotube samples. By using a metal-containing diblock copolymer catalyst, carbon nanotubes with a diameter of 4 to 7 nm were synthesized. The effect of growth parameters was studied and these parameters were optimized. The growth of high density (˜ 109/cm2) and large coverage area (˜ 1 cm2) carbon nanotube film on glass substrate at low growth temperature was realized. Based on a series of experiments, the effects of oxygen atoms and Ti/N underlayer on the growth were studied. A series of experiments were evaluated to characterize the field emission properties of the various carbon nanotube cathodes. A simple technique of scratching the pattern surface by a cotton swab was found effective to activate more carbon nanotubes to emit. By using the techniques of photolithography and shadow mask, various carbon nanotube patterns were achieved in order to obtain high emission current density and a low threshold electric field. The lowest threshold electric field was found to be 2.3 V/um. The highest current density was found to be 2.2 mA/cm2 when the electric field was 4.7 V/um. Our work shows that it is feasible to provide greater control over the fabrication of carbon nanotubes so that more obstacles in the broad application of carbon nanotubes can be overcome.

  12. Preparation of magnetic carbon nanotubes with hierarchical copper silicate nanostructure for efficient adsorption and removal of hemoglobin

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Wang, Yongtao; Zhang, Yanwei; Ding, Lei; Zheng, Jing; Xu, Jingli

    2016-07-01

    The controllable synthesis of materials with the desired structure and dimensionality is of great significance in material science. In this work, the hierarchical CNTs/Fe3O4@copper silicate (CNTs/Fe3O4@CuSilicate) composites were synthesized via a simple chemical conversion route by using CNTs/Fe3O4@SiO2 nanocables as template. Firstly, magnetic CNTs composites (CNTs/Fe3O4) were synthesized by the high temperature decomposition process using the iron acetylacetonate as raw materials. Then a layer of SiO2 can be easily coated on the magnetic CNTs by the stöber method, which were then converted into CNTs/Fe3O4@CuSilicate composites by hydrothermal reaction between the silica shell and copper ions in alkaline solution. The resulting CNTs/Fe3O4@CuSilicate composites hold merits such as magnetic responsivity, good dispersibility, and large specific surface area. Moreover, the CNTs/Fe3O4@copper silicate composites have strong affinity toward bovine hemoglobin (BHb), which were successfully applied to convenient, efficient, and fast removal of abundant proteins (HHb and HSA) in human blood.

  13. A promising pathway to make multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Setlur, A. A.; Doherty, S. P.; Dai, J. Y.; Chang, R. P. H.

    2000-05-01

    Current theories for multiwalled nanotube growth (without metal catalysts) describe the growth of multiwalled nanotubes by the addition of carbon atoms, ions, or small molecules to an open ended nanotube nucleus. In this letter, we describe a method to make carbon nanotubes similar in quality to those found on the cathode deposit of the carbon arc by manipulating the heat treatment of various nongraphitizable carbon precursors. It is proposed that this method of making nanotubes via heat treatments is analogous to a graphitization process, where aromatic/graphitic fragments in disordered carbons assemble into three-dimensional graphitic structures. In addition, we have demonstrated that simple precursors, such as sucrose, can be used as starting materials. These experiments offer new opportunities to understand nanotube growth and could lead to scalable methods to make multiwalled nanotubes.

  14. A promising pathway to make multiwalled carbon nanotubes

    SciTech Connect

    Setlur, A. A.; Doherty, S. P.; Dai, J. Y.; Chang, R. P. H.

    2000-05-22

    Current theories for multiwalled nanotube growth (without metal catalysts) describe the growth of multiwalled nanotubes by the addition of carbon atoms, ions, or small molecules to an open ended nanotube nucleus. In this letter, we describe a method to make carbon nanotubes similar in quality to those found on the cathode deposit of the carbon arc by manipulating the heat treatment of various nongraphitizable carbon precursors. It is proposed that this method of making nanotubes via heat treatments is analogous to a graphitization process, where aromatic/graphitic fragments in disordered carbons assemble into three-dimensional graphitic structures. In addition, we have demonstrated that simple precursors, such as sucrose, can be used as starting materials. These experiments offer new opportunities to understand nanotube growth and could lead to scalable methods to make multiwalled nanotubes. (c) 2000 American Institute of Physics.

  15. Adsorption of Gases on Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Mbaye, Mamadou Thiao

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

  16. 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

  17. Nanosystems of Polymerized Fullerenes and Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Scharff, Peter; Cui, Shen

    Nanosystems based on polymerized fullerenes and carbon-nanotubes begin to play an important role in the field of nanotechnology. Nanotubes can be used as molecular wires, and can even figure as building elements for molecular electronics. Furthermore nanotubes can be used as amplifiers in composite materials, as a result of their unique mechanical properties. Many other applications, as for example as electron emitters for flat screens, are currently under development. Fullerens are known to be strong electron acceptors, which enables them to support the electron-hole pair separation in polymer based photovoltaic cells. The use of fulleren chains instead of fullerenes could improve the anisotropic electronic conductivity in the contained polymer layer, and therefore enhance their performance.

  18. Spin-based Optomechanics with Carbon Nanotubes

    PubMed Central

    Li, Jin-Jin; Zhu, Ka-Di

    2012-01-01

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

  19. Carbon nanotube photo-thermo-mechanical actuator.

    PubMed

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

    2011-02-01

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

  20. 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.

  1. Ag-catalysed cutting of multi-walled carbon nanotubes.

    PubMed

    La Torre, A; Rance, G A; Miners, S A; Herreros Lucas, C; Smith, E F; Fay, M W; Zoberbier, T; Giménez-López, M C; Kaiser, U; Brown, P D; Khlobystov, A N

    2016-04-29

    In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon-carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes.

  2. Ag-catalysed cutting of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    La Torre, A.; Rance, G. A.; Miners, S. A.; Herreros Lucas, C.; Smith, E. F.; Fay, M. W.; Zoberbier, T.; Giménez-López, M. C.; Kaiser, U.; Brown, P. D.; Khlobystov, A. N.

    2016-04-01

    In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon-carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes.

  3. Carbon Nanotubes for Space Photovoltaic Applications

    NASA Technical Reports Server (NTRS)

    Efstathiadis, Harry; Haldar, Pradeep; Landi, Brian J.; Denno, Patrick L.; DiLeo, Roberta A.; VanDerveer, William; Raffaelle, Ryne P.

    2007-01-01

    Carbon nanotubes (CNTs) can be envisioned as an individual graphene sheet rolled into a seamless cylinder (single-walled, SWNT), or concentric sheets as in the case of a multi-walled carbon nanotube (MWNT) (1). The role-up vector will determine the hexagonal arrangement and "chirality" of the graphene sheet, which will establish the nanotube to be metallic or semiconducting. The optoelectronic properties will depend directly on this chiral angle and the diameter of the SWNT, with semiconductor types exhibiting a band gap energy (2). Characteristic of MWNTs are the concentric graphene layers spaced 0.34 nm apart, with diameters from 10-200 nm and lengths up to hundreds of microns (2). In the case of SWNTs, the diameters range from 0.4 - 2 nm and lengths have been reported up to 1.5 cm (3). SWNTs have the distinguishable property of "bundling" together due to van der Waal's attractions to form "ropes." A comparison of these different structural types is shown in Figure 1. The use of SWNTS in space photovoltaic (PV) applications is attractive for a variety of reasons. Carbon nanotubes as a class of materials exhibit unprecedented optical, electrical, mechanical properties, with the added benefit of being nanoscale in size which fosters ideal interaction in nanomaterial-based devices like polymeric solar cells. The optical bandgap of semiconducting SWNTs can be varied from approx. 0.4 - 1.5 eV, with this property being inversely proportional to the nanotube diameter. Recent work at GE Global Research has shown where a single nanotube device can behave as an "ideal" pn diode (5). The SWNT was bridged over a SiO2 channel between Mo contacts and exhibited an ideality factor of 1, based on a fit of the current-voltage data using the diode equation. The measured PV efficiency under a 0.8 eV monochromatic illumination showed a power conversion efficiency of 0.2 %. However, the projected efficiency of these junctions is estimated to be > 5 %, especially when one considers the

  4. Electrochemical Characterization of Carbon Nanotubes for Fuel Cell MEA's

    NASA Technical Reports Server (NTRS)

    Panagaris, Jael; Loyselle, Patricia

    2004-01-01

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

  5. Sagnac interference in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Bishara, Waheb; Refael, Gil; Bockrath, Marc

    2008-10-01

    The Sagnac interference mode arises when two interfering counterpropogating beams traverse a loop, but with their velocities detuned by a small amount 2u , with vR/L=vF±u . In this paper we perform a perturbative nonequilibrium calculation of Sagnac interference in single-channel wires as well as armchair nanotube loops. We study the dependence of the Sagnac conductance oscillations on temperature and interactions. We find that the Sagnac interference is not destroyed by strong interactions, but becomes weakly dependent on the velocity detuning u . In armchairs nanotubes with typical interaction strength, 0.25≤g≤0.5 , we find that the necessary temperature for observing the interference effect, TSAG is also only weakly dependent on the interaction, and is enhanced by a factor of 8 relative to the temperature necessary for observing Fabry-Pérot interference in the same system, TFP .

  6. Carbon nanotube materials from hydrogen storage

    SciTech Connect

    Dillon, A.C.; Bekkedahl, T.A.; Cahill, A.F.

    1995-09-01

    The lack of convenient and cost-effective hydrogen storage is a major impediment to wide scale use of hydrogen in the United States energy economy. Improvements in the energy densities of hydrogen storage systems, reductions in cost, and increased compatibility with available and forecasted systems are required before viable hydrogen energy use pathways can be established. Carbon-based hydrogen adsorption materials hold particular promise for meeting and exceeding the U.S. Department of Energy hydrogen storage energy density targets for transportation if concurrent increases in hydrogen storage capacity and carbon density can be achieved. These two goals are normally in conflict for conventional porous materials, but may be reconciled by the design and synthesis of new adsorbent materials with tailored pore size distributions and minimal macroporosity. Carbon nanotubes offer the possibility to explore new designs for adsorbents because they can be fabricated with small size distributions, and naturally tend to self-assemble by van der Waals forces. This year we report heats of adsorption for hydrogen on nanotube materials that are 2 and 3 times greater than for hydrogen on activated carbon. The hydrogen which is most strongly bound to these materials remains on the carbon surface to temperatures greater than 285 K. These results suggest that nanocapillary forces are active in stabilizing hydrogen on the surfaces of carbon nanotubes, and that optimization of the adsorbent will lead to effective storage at higher temperatures. In this paper we will also report on our activities which are targeted at understanding and optimizing the nucleation and growth of single wall nanotubes. These experiments were made possible by the development of a unique feedback control circuit which stabilized the plasma-arc during a synthesis run.

  7. Sub-10 nm carbon nanotube transistor.

    PubMed

    Franklin, Aaron D; Luisier, Mathieu; Han, Shu-Jen; Tulevski, George; Breslin, Chris M; Gignac, Lynne; Lundstrom, Mark S; Haensch, Wilfried

    2012-02-01

    Although carbon nanotube (CNT) transistors have been promoted for years as a replacement for silicon technology, there is limited theoretical work and no experimental reports on how nanotubes will perform at sub-10 nm channel lengths. In this manuscript, we demonstrate the first sub-10 nm CNT transistor, which is shown to outperform the best competing silicon devices with more than four times the diameter-normalized current density (2.41 mA/μm) at a low operating voltage of 0.5 V. The nanotube transistor exhibits an impressively small inverse subthreshold slope of 94 mV/decade-nearly half of the value expected from a previous theoretical study. Numerical simulations show the critical role of the metal-CNT contacts in determining the performance of sub-10 nm channel length transistors, signifying the need for more accurate theoretical modeling of transport between the metal and nanotube. The superior low-voltage performance of the sub-10 nm CNT transistor proves the viability of nanotubes for consideration in future aggressively scaled transistor technologies.

  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. Coupling of Carbon Nanotubes to Metallic Contacts

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  10. 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.

  11. 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

  12. Mesoscale mechanics of twisting carbon nanotube yarns

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  13. Synthesis of Carbon Nanotubes Using Sol Gel Route

    NASA Astrophysics Data System (ADS)

    Abdel-Fattah, Tarek

    2002-12-01

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

  14. Spectroscopic study of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Curran, Seamus; Weldon, Declan N.; Blau, Werner J.; Zandbergen, Henny W.; Kastner, J.; Kuzmany, Hans

    1994-11-01

    We present a comprehensive experimental study of the vibrational spectra of nanotubes. There are two main lines observed in the Raman spectrum, one positioned at 1350 cm-1, the D line, and the other at 1580 cm-1, the G line. Both these lines are very similar to those seen with disordered graphite. The disorder induced D line is very weak compared to the G line which is indicative of high crystalline materials. The position and intensity of the D line strongly depends on the energy of the exciting laser. This dispersion effect was also observed for graphitic particles and may be explained by a photoselective resonance process of nanotubes with different sizes. There are two optically active modes in the Infrared spectrum for highly orientated polycrystalline graphite which are the E1u and A2u modes. The E1u mode is positioned at 1587 cm-1 while the A2u mode is positioned at 868 cm-1. The Infrared spectrum of the nanotubes shows both modes although the E1u mode is downshifted to 1575 cm-1.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Mayo, Nathanael; Kuznetsov, Alexander; Zakhidov, Anvar

    2011-03-01

    Injecting high electronic charge densities can profoundly change the optical, electrical, and magnetic properties of materials. Evidence suggests a possibility of significantly improving conductivity of carbon nanotubes through double layer charge injection. Double layer charge injection can prove to be a powerful method when applied to carbon nanotubes because of theirs high surface area and chemical stability. Investigation has commenced on the effect of charging on various types of carbon nanotubes, specifically 99% purified single wall semiconducting and single wall metallic tubes. An electrical double layer is electrochemically introduced upon a sheet of carbon nanotubes via application of potential (up to +/- 5 volts) to a sample immersed in ionic-liquid-based electrolyte. Resistance of carbon nanotube as a function of applied charging voltage is recorded to determine the effects of charge injection. Results show that the electrical double layer considerably reduces the resistance across both samples. ESR/LFMA studies combined with low temperature magnetic and transport measurements are conducted to search for charge injection induced superconductivity in carbon nanotubes. Supported by AFOSR grant FA 9550-09-1-0384.

  17. 77 FR 39236 - Nanomaterial Case Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-02

    ... AGENCY Nanomaterial Case Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether... Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether Flame-Retardant Coatings... ``Nanomaterial Case Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether...

  18. Remote Joule heating by a carbon nanotube

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

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

  19. Spectroscopy of Optical Excitations in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Ma, Yingzhong

    2006-03-01

    Understanding the optical spectra and electronic excited state dynamics of carbon naotubes is important both for fundamental research and a wide variety of potential applications. In this presentation, we will report the results of a systematic study on semiconducting single-walled carbon nanotubes (SWNTs) obtained by utilizing complementary femtosecond spectroscopic techniques, including fluorescence up-conversion, frequency-resolved transient absorption, and three-pulse photon echo peakshift (3PEPS) spectroscopy. Our efforts have focused on optically selective detection of the spectra and dynamics associated with structurally distinct semiconducting SWNT species. Using individual nanotube enriched micelle-dispersed SWNT preparations, in combination with resonant excitation and detection, has enabled us to independently access selected species, such as the (8,3), (6,5), (7,5), (11,0), (7,6) and (9,5) nanotubes. We will discuss the following topics: (1) the excitonic nature of the elementary excitation and its unambiguous identification from direct determination of the exciton binding energy for a selected semiconducting nanotube, the (8,3) tube; (2) the spectroscopic and dynamical signatures of exciton-exciton annihilation and its predominant role in governing ultrafast excited state relaxation; (3) the annihilation-concomitant exciton dissociation and the spectroscopic and dynamic features of the resulting electron-hole continuum; (4) timescales characterizing the ultrafast thermalization processes. In addition, we will demonstrate the power of 3PEPS spectroscopy to elucidate the spectral properties and dynamics of SWNTs. This work was supported by the NSF.

  20. Developing Carbon Nanotube Standards at NASA

    NASA Technical Reports Server (NTRS)

    Nikolaev, Pasha; Arepalli, Sivaram; Sosa, Edward; Gorelik, Olga; Yowell, Leonard

    2007-01-01

    Single wall carbon nanotubes (SWCNTs) are currently being produced and processed by several methods. Many researchers are continuously modifying existing methods and developing new methods to incorporate carbon nanotubes into other materials and utilize the phenomenal properties of SWCNTs. These applications require availability of SWCNTs with known properties and there is a need to characterize these materials in a consistent manner. In order to monitor such progress, it is critical to establish a means by which to define the quality of SWCNT material and develop characterization standards to evaluate of nanotube quality across the board. Such characterization standards should be applicable to as-produced materials as well as processed SWCNT materials. In order to address this issue, NASA Johnson Space Center has developed a protocol for purity and dispersion characterization of SWCNTs. The NASA JSC group is currently working with NIST, ANSI and ISO to establish purity and dispersion standards for SWCNT material. A practice guide for nanotube characterization is being developed in cooperation with NIST. Furthermore, work is in progress to incorporate additional characterization methods for electrical, mechanical, thermal, optical and other properties of SWCNTs.