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1

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

E-print Network

Carbon nanotubes in confined magneticCarbon nanotubes in confined magnetic fields: thefieldsOutline Aharonov-Bohm oscillations in Carbon nanotubes Confined and extended magnetic fields & Curvature effects as a change in the interference pattern #12;The AB effect in carbon nano-tubes A. Bachtold et al., Nature 397

Marini, Andrea

2

Flightweight Carbon Nanotube Magnet Technology  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

3

Magnetic Brightening of Carbon Nanotube Photoluminescence through  

E-print Network

Magnetic Brightening of Carbon Nanotube Photoluminescence through Symmetry Breaking Jonah Shaver report that symmetry breaking by a magnetic field can drastically increase the photoluminescence quantum macroscopic property of the system: photoluminescence (PL) quantum yield (QY). Specifically, we found

Kono, Junichiro

4

Carbon nanotube based magnetic tunnel junctions  

PubMed

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

Mehrez; Taylor; Guo; Wang; Roland

2000-03-20

5

Magnetic Ordering in Carbon Nanotubes  

E-print Network

The physical origin of the mechanism of the formation of ferromagnetic ordering in carbon nanotubes (NTs) produced by high energy ion beam modification of diamond single crystals in $$ and $$ directions has been found. It is determined by asymmetry of spin density distribution of Su-Schrieffer-Heeger topological soliton lattice formed in 1D Fermi quantum liquid state of $\\pi$-electronic subsystem of given NTs. The phenomenon of formation of antiferromagnetic ordering coexisting with superconductivity at room temperature in carbon NTs, produced by high energy ion beam modification of diamond single crystals in $$ direction is discussed.

Yerchuck, Dmitri; Dovlatova, Alla; Yerchak, Yauhen; Alexandrov, Andrey

2012-01-01

6

Carbon nanotubes in confined magnetic fields: gap oscillations and  

E-print Network

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

Marini, Andrea

7

Magnetic properties of carbon nanotubes with and without catalyst  

Microsoft Academic Search

In this paper we report on the magnetic properties of single- and multiwalled carbon nanotubes synthesized using different chemical vapour deposition methods and with variety of catalyst materials (ferromagnetic Fe, FeCo and diamagnetic Re). Different methods yield carbon nanotubes with different morphologies and different quantity of residual catalyst material. Catalyst particles are usually encapsulated in the nanotubes and influence the

Kamil Lipert; Manfred Ritschel; Albrecht Leonhardt; Yulia Krupskaya; Bernd Büchner; Rüdiger Klingeler

2010-01-01

8

Magnetic Brightening of Dark Excitons in Carbon Nanotubes  

E-print Network

Magnetic Brightening of Dark Excitons in Carbon Nanotubes Jonah Shaver 1 , Sasa Zaric 2 , Erik H properties of excitons in single-walled carbon nanotubes, we have studied photoluminescence from-field experiments (nanotubes at room temperature; photoluminescence peaks showed B

Maruyama, Shigeo

9

Integration of carbon nanotubes into diluted magnetic semiconductor  

Microsoft Academic Search

Carbon nanotubes (CNTs) were grown using catalytic pyrolysis of acetylene on a thin-film-diluted magnetic semiconductor (Co-8 at. % doped TiO2) without consuming the host layer of semiconductor TiO2. Effects of the thickness of the diluted magnetic semiconductor layer and the stacking structure on the growth of the carbon nanotubes were examined. The external diameter and crystalline structure of the nanotubes

Yun-Hi Lee; J. M. Yoo; J. Ah Lee; S. Y. Ahn; J. Joo; S. Lee; D. H. Kim; B. K. Ju; K. J. Song

2005-01-01

10

Magnetically induced field effect in carbon nanotube devices.  

PubMed

Three-terminal devices with conduction channels formed by quasi-metallic carbon nanotubes (CNTs) are shown to operate as nanotube-based field-effect transistors under strong magnetic fields. The off-state conductance of the devices varies exponentially with the magnetic flux intensity. We extract the quasi-metallic CNT chirality as well as the characteristics of the Schottky barriers formed at the metal-nanotube contacts from the temperature-dependent magnetoconductance measurements. PMID:17385934

Fedorov, Georgy; Tselev, Alexander; Jiménez, David; Latil, Sylvain; Kalugin, Nikolai G; Barbara, Paola; Smirnov, Dmitry; Roche, Stephan

2007-04-01

11

Integration of carbon nanotubes into diluted magnetic semiconductor  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) were grown using catalytic pyrolysis of acetylene on a thin-film-diluted magnetic semiconductor (Co-8at.% doped TiO2) without consuming the host layer of semiconductor TiO2. Effects of the thickness of the diluted magnetic semiconductor layer and the stacking structure on the growth of the carbon nanotubes were examined. The external diameter and crystalline structure of the nanotubes showed correlation with the structure of the magnetic catalyst Co within the nanotubes or at the end of the tube. After the growth of CNTs, the TiO2 layer still maintained its semiconducting properties in view of the temperature dependent resistance behavior. Moreover, we studied the influence of the electrical resistivity, i.e, the thickness as a process parameter, of the diluted magnetic semiconductor underlayer, which determines the growth height and the crystalline quality of the carbon nanotubes, on the nanotubes' growth behavior. Finally, we measured the magnetic behavior of the heterosystem and interpreted the results due to the action of the properties of the catalytic diluted magnetic semiconductor underlayer. Our result shows a promising recipe for the fabrication of one-dimensional CNT—two-dimensional magnetic-metal-doped magnetic semiconductor and/or wide-band-gap insulator.

Lee, Yun-Hi; Yoo, J. M.; Lee, J. Ah; Ahn, S. Y.; Joo, J.; Lee, S.; Kim, D. H.; Ju, B. K.; Song, K. J.

2005-09-01

12

Detection of nanoscale magnetic activity using a single carbon nanotube.  

PubMed

The ultimate conductometric sensor for ferromagnetic activity of nanoscale magnetic materials could be a single carbon nanotube. We show that the electrical conductance of an individual carbon nanotube is sensitive to magnetic transitions of nanoscale magnets embedded inside it. To establish this, multiwall carbon nanotubes were impregnated with cobalt nanoclusters. Temperature dependence of conductance (5 K < T <300 K) of these nanotubes shows the usual Lüttinger-liquid power law behavior at higher temperatures and an onset of Coulomb blockade at lower temperatures. At the lowest temperature (T approximately 6 K), the differential conductance (dI/dV versus V) develops aperiodic fluctuations under an external magnetic field B, the rms amplitude of which grows with the magnitude of the field itself. Low-temperature magnetoconductance, studied as function of temperature and bias, can be interpreted in terms of weak antilocalization effects due to the presence of the magnetized clusters. The temperature dependence of magnetoconductance further presents a "peak"-like feature and slow dynamics around T =55 K, which depend on the magnitude and history of the applied B field. These observations indicate a sensitivity of electronic transport in the multiwall nanotubes to the dynamics of nanoscale magnets at low temperature. PMID:19367805

Soldano, Caterina; Kar, Swastik; Talapatra, Saikat; Nayak, Saroj; Ajayan, Pulickel M

2008-12-01

13

Electrical detection of individual magnetic nanoparticles encapsulated in carbon nanotubes.  

PubMed

We report on low-temperature electrical transport measurements of single-walled carbon nanotubes (SWNTs) filled in their inner core with one-dimensional cobalt nanoparticles. The electrical transport properties of the hybrid devices are strongly sensitive to the magnetization reversal of isolated magnetic nanoparticles, resulting in strong hysteretic variations of the magnetoconductance. The magnetic anisotropy of a one-dimensional encapsulated cobalt nanoparticle is investigated, establishing an unusually strong dominating contribution of magnetic surface anisotropy. PMID:21344889

Cleuziou, Jean-Pierre; Wernsdorfer, Wolfgang; Ondarçuhu, Thierry; Monthioux, Marc

2011-03-22

14

Carbon nanotubes and magnetic nanomaterials as substratum for neuroscience applications  

NASA Astrophysics Data System (ADS)

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

Aatre, Kiran R.

15

Electronic and Magnetic Properties of Partially-Open Carbon Nanotubes  

Microsoft Academic Search

On the basis of the spin-polarized density functional theory calculations, we demonstrate that partially-open carbon nanotubes (CNTs) observed in recent experiments have rich electronic and magnetic properties which depend on the degree of the opening. A partially-open armchair CNT is converted from a metal to a semiconductor, and then to a spin-polarized semiconductor by increasing the length of the opening

Bing Huang; Young-Woo Son; Gunn Kim; Wenhui Duan; Jisoon Ihm

2009-01-01

16

Nonmagnetic carbon nanotubes  

Microsoft Academic Search

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

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

2009-01-01

17

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

PubMed

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

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

2011-01-25

18

Magnetorheological properties of a magnetic nanofluid with dispersed carbon nanotubes.  

PubMed

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

Felicia, Leona J; Philip, John

2014-02-01

19

Sensitive magnetic force detection with a carbon nanotube resonator  

SciTech Connect

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

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

2014-03-21

20

Giant magnetic moment at open ends of multiwalled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The attractions of cantilevers made of multiwalled carbon nanotubes (MWNTs) and secured on one end are studied in the non-uniform magnetic field of a permanent magnet. Under an optical microscope, the positions and the corresponding deflections of the original cantilevers (with iron catalytic nanoparticles at the free end) and corresponding cut-off cantilevers (the free ends consisting of open ends of MWNTs) are studied. Both kinds of CNT cantilevers are found to be attracted by the magnet, and the point of application of force is proven to be at the tip of the cantilever. By measuring and comparing deflections between these two kinds of cantilevers, the magnetic moment at the open ends of the CNTs can be quantified. Due to the unexpectedly high value of the magnetic moment at the open ends of carbon nanotubes, it is called giant magnetic moment, and its possible mechanisms are proposed and discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 10774032 and 51472057) and the Instrument Developing Project of the Chinese Academy of Sciences (Grant No. Y2010031).

Wang, Gang; Chen, Min-Jiang; Yu, Fang; Xue, Lei-Jiang; Deng, Ya; Zhang, Jian; Qi, Xiao-Ying; Gao, Yan; Chu, Wei-Guo; Liu, Guang-Tong; Yang, Hai-Fang; Gu, Chang-Zhi; Sun, Lian-Feng

2015-01-01

21

Anisotropic conductivity of magnetic carbon nanotubes embedded in epoxy matrices  

PubMed Central

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

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

2010-01-01

22

Magnetic nanotubes  

DOEpatents

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

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

2010-11-16

23

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

24

Carbon nanotube decorated magnetic microspheres as an affinity matrix for biomolecules  

E-print Network

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

Yanikoglu, Berrin

25

Magnetic study of iron-containing carbon nanotubes: Feasibility for magnetic hyperthermia  

Microsoft Academic Search

We present a detailed magnetic study of iron containing carbon nanotubes (Fe-CNT), which highlights their potential for contactless magnetic heating in hyperthermia cancer treatment. Magnetic field dependent AC inductive heating experiments on Fe-CNT dispersions show a substantial temperature increase of Fe-CNT dispersions in applied AC magnetic fields. DC and AC magnetization studies have been done in order to elucidate the

Y. Krupskaya; C. Mahn; A. Parameswaran; A. Taylor; K. Krämer; S. Hampel; A. Leonhardt; M. Ritschel; B. Büchner; R. Klingeler

2009-01-01

26

Anomalous magnetization of a carbon nanotube as an excitonic insulator  

NASA Astrophysics Data System (ADS)

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

Rontani, Massimo

2014-11-01

27

Magnetoconductance of carbon nanotubes  

Microsoft Academic Search

As a result of the interaction between the spin and the magnetic field (B), special step structures are predicted to exist in the ballistic magnetoconductance of carbon nanotubes. The electronic structure of a carbon nanotube drastically changes from a metal (semiconductor) to a semiconductor (metal) during the variation of the magnetic flux. When the spin-B interaction is neglected, the Fermi

M. F. Lin; Kenneth W.-K. Shung

1995-01-01

28

Synthesis of magnetic carbon nanotube and photocatalytic dye degradation ability.  

PubMed

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

Mahmoodi, Niyaz Mohammad

2014-09-01

29

Electronic and magnetic properties of partially open carbon nanotubes.  

PubMed

On the basis of the spin-polarized density functional theory calculations, we demonstrate that partially open carbon nanotubes (CNTs) observed in recent experiments have rich electronic and magnetic properties which depend on the degree of the opening. A partially open armchair CNT is converted from a metal to a semiconductor and then to a spin-polarized semiconductor by increasing the length of the opening on the wall. Spin-polarized states become increasingly more stable than nonmagnetic states as the length of the opening is further increased. In addition, external electric fields or chemical modifications are usable to control the electronic and magnetic properties of the system. We show that half-metallicity may be achieved and the spin current may be controlled by external electric fields or by asymmetric functionalization of the edges of the opening. Our findings suggest that partially open CNTs may offer unique opportunities for the future development of nanoscale electronics and spintronics. PMID:19911795

Huang, Bing; Son, Young-Woo; Kim, Gunn; Duan, Wenhui; Ihm, Jisoon

2009-12-16

30

Electrostatic waves in carbon nanotubes with an axial magnetic field  

SciTech Connect

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

Abdikian, Alireza [Department of Physics, Malayer University, Malayer 65719-95863 (Iran, Islamic Republic of)] [Department of Physics, Malayer University, Malayer 65719-95863 (Iran, Islamic Republic of); Bagheri, Mehran [Laser and Plasma Research Institute, Shahid Beheshti University, G. C., Evin, Tehran 19835-63113 (Iran, Islamic Republic of)] [Laser and Plasma Research Institute, Shahid Beheshti University, G. C., Evin, Tehran 19835-63113 (Iran, Islamic Republic of)

2013-10-15

31

Magnetic Property Measurements on Single Wall Carbon Nanotube-Polyimide Composites  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

32

Selective actuation of arrays of carbon nanotubes using magnetic resonance.  

PubMed

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

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

2013-07-23

33

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

E-print Network

Enhancement of thermal and electrical properties of carbon nanotube polymer composites by magnetic by magnetic alignment during processing. The electrical transport properties of the composites are mainly of the MWNT polymer in Ref. 9 was verified by transmission electron microscopy TEM , electrical, magnetic

Garmestani, Hamid

34

Tuning the band gap of semiconducting carbon nanotube by an axial magnetic field  

NASA Astrophysics Data System (ADS)

We have investigated the magnetic field dependence of transfer characteristics of a device fabricated in a configuration of a field-effect transistor with a conduction channel formed by a semiconducting multiwalled carbon nanotube. Our results unambiguously indicate that an axial magnetic field suppresses the band gap of the nanotube. Quantitative analysis of the data indicates linear dependence of the band gap on magnetic field as well as a linear splitting between the K and K' subbands of the band structure of the nanotube.

Fedorov, G.; Barbara, P.; Smirnov, D.; Jiménez, D.; Roche, S.

2010-03-01

35

Enhanced magnetism in Fe-filled carbon nanotubes produced by pyrolysis of ferrocene  

Microsoft Academic Search

By optimization of the synthesis of ferromagnetic-filled carbon nanotube ensembles on Si substrates (catalytic decomposition of ferrocene) and following annealing at 645 °C, marked hysteresis loops can be measured by the alternating-gradient method. Unusually high coercivities and strong anisotropies with an easy magnetic axis parallel to the alignment of the nanotubes are observed from the as-grown samples, whereas an enhanced

A. Leonhardt; M. Ritschel; D. Elefant; N. Mattern; K. Biedermann; S. Hampel; Ch. Müller; T. Gemming; B. Büchner

2005-01-01

36

Chemical disorder strength in carbon nanotubes: Magnetic tuning of quantum transport regimes  

Microsoft Academic Search

We report on a theoretical study of quantum transport in carbon nanotubes in the presence of chemical-disorder-induced quasibound states, with a quantitative analysis of the relationship between the energy-dependent elastic mean free path and localization length. An external magnetic field applied perpendicularly to the nanotube axis is shown to induce a floating up in energy of the quasibound states, which

Rémi Avriller; Sylvain Latil; François Triozon; X. Blase; Stephan Roche

2006-01-01

37

Photophysics of carbon nanotubes  

E-print Network

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

Samsonidze, Georgii G

2007-01-01

38

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

NASA Astrophysics Data System (ADS)

Coating of carbon nanotubes (CNTs) with magnetic nanoparticles (NPs) imparts novel magnetic, optical, and thermal properties with potential applications in the biomedical domain. Multi-walled CNTs have been decorated with iron oxide superparamagnetic NPs. Two different approaches have been investigated based on ligand exchange or ``click chemistry''. The presence of the NPs on the nanotube surface allows conferring magnetic properties to CNTs. We have evaluated the potential of the NP/CNT hybrids as a contrast agent for magnetic resonance imaging (MRI) and their interactions with cells. The capacity of the hybrids to magnetically monitor and manipulate cells has also been investigated. The NP/CNTs can be manipulated by a remote magnetic field with enhanced contrast in MRI. They are internalized into tumor cells without showing cytotoxicity. The labeled cells can be magnetically manipulated as they display magnetic mobility and are detected at a single cell level through high resolution MRI.Coating of carbon nanotubes (CNTs) with magnetic nanoparticles (NPs) imparts novel magnetic, optical, and thermal properties with potential applications in the biomedical domain. Multi-walled CNTs have been decorated with iron oxide superparamagnetic NPs. Two different approaches have been investigated based on ligand exchange or ``click chemistry''. The presence of the NPs on the nanotube surface allows conferring magnetic properties to CNTs. We have evaluated the potential of the NP/CNT hybrids as a contrast agent for magnetic resonance imaging (MRI) and their interactions with cells. The capacity of the hybrids to magnetically monitor and manipulate cells has also been investigated. The NP/CNTs can be manipulated by a remote magnetic field with enhanced contrast in MRI. They are internalized into tumor cells without showing cytotoxicity. The labeled cells can be magnetically manipulated as they display magnetic mobility and are detected at a single cell level through high resolution MRI. Electronic supplementary information (ESI) available: Additional TEM image, DLS diagram, and FT-IR data. See DOI: 10.1039/c3nr00636k

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

2013-05-01

39

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

40

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

PubMed

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

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

2011-10-28

41

Magnetic and Reflection Loss Characteristics of Substituted Barium Ferrite\\/Functionalized Multiwalled Carbon Nanotube  

Microsoft Academic Search

Magnetic multiwalled carbon nanotube (MWCNTs) nanocomposites have been created by the assembly of Mg-Ni-Ti substituted barium ferrite nanoparticles onto surface of MWCNTs. X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to demonstrate the successful attachment of ferrite nanoparticles to MWCNTs. Vibrating sample magnetometer (VSM) confirms the relatively strong dependence of saturation of magnetization and coercivity with the volume

Ali Ghasemi; Sirus Javadpour; Xiaoxi Liu; Akimitsu Morisako

2011-01-01

42

Carbon Nanotubes  

NSDL National Science Digital Library

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

Meyyappan, Meyya

43

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

PubMed Central

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

Masotti, Andrea; Caporali, Andrea

2013-01-01

44

Quantum transport in carbon nanotube field effect transistors in high magnetic fields  

NASA Astrophysics Data System (ADS)

The dissertation is a study of data taken from carbon nanotube field effect transistors (CNTFET). The data presented was taken at two locations, University of Pennsylvania in Philadelphia, PA and at Lehigh University in Bethlehem, PA. The samples are exposed to very low temperature using dilution refrigerator techniques and placed in high magnetic fields using a superconducting magnet. One of the main focuses will be on the effect an external magnetic field can produce on the transport properties of a CNTFET. Particular attention will be paid to the Kondo effect and Coulomb blockade phenomena. Comparisons are drawn between the observed behavior of the samples studied and with published works on carbon nanotube electronics and traditional semiconductor quantum dots.

Stephens, Jeffrey Dale

45

Carbon Nanotube Image Gallery  

NSDL National Science Digital Library

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

46

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

PubMed

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

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

2011-07-01

47

Fast Characterization of Magnetic Impurities in Single-Wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

48

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

E-print Network

Single-wall carbon nanotubes are considered in the presence of an external magnetic field with inhomogeneous transverse component. The continuum model is employed where the dynamics of the charge carriers is governed by the Dirac-Weyl equation. It is shown that a small fluctuation of the transverse field around a constant value represented by a finite-gap vector potential provides exact solutions of the stationary equation. An example is elaborated in detail. The spectrum of the system manifests remarkable stability with respect to small perturbations of the longitudinal momentum. Nonlinear, N=2 supersymmetry associated with the metallic and the maximally semi-conducting nanotubes is discussed.

Jakubsky, Vit; Negro, Javier

2013-01-01

49

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

50

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

PubMed Central

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

Raniszewski, Grzegorz; Pyc, Marcin; Kolacinski, Zbigniew

2014-01-01

51

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

SciTech Connect

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

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

2014-04-15

52

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

E-print Network

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

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

2011-01-01

53

Carbon nanotube nanoelectrode arrays  

DOEpatents

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.

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

2008-11-18

54

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

PubMed Central

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

Pop?awska, Magdalena

2013-01-01

55

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

SciTech Connect

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?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.

Diamantopoulou, A.; Glenis, S.; Likodimos, V.; Guskos, N. [Department of Solid State Physics, Faculty of Physics, University of Athens, Panepistimioupolis, GR-157 84 Athens (Greece)

2014-08-28

56

Unusual magnetic behavior of SiCN/multiwalled carbon nanotubes nanocomposites  

NASA Astrophysics Data System (ADS)

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

Francis, A.; Riedel, R.

2009-04-01

57

Selection rules and linear absorption spectra of carbon nanotubes in axial magnetic fields  

NASA Astrophysics Data System (ADS)

We derive a transparent and easy-to-use analytic expression for the selection rules and the optical dipole matrix elements for carbon nanotubes of arbitrary chirality in the presence of axial magnetic fields using a single-orbital ?-electron tight-binding model. From this, we calculate the linear absorption spectrum for arbitrary polarization directions of the incident light, providing insight into all optically allowed transition. We show that the transverse absorption peaks can be selectively excited with circularly polarized light and spectrally resolved in an axial magnetic field.

Liu, Hong; Schumacher, Stefan; Meier, Torsten

2013-07-01

58

Magnetization for lower temperature, selective diamond and carbon nanotube formation: A milestone in carbon physicochemical condensation  

Microsoft Academic Search

Diamonds and carbon nanotubes (CNTs) have extraordinary properties with the potential for vast technological and scientific advancements. However, the syntheses of these super materials have required extreme conditions. Recent synthetic developments surrounding catalytic chemical vapor deposition (CCVD) have contributed to more suitable, practical and economical preparations, but more progress is needed for better selectivity, purity, and mass production of CNTs

Reginald B. Little; Robert Goddard

2004-01-01

59

Carbon Nanotube Quantum Resistors  

Microsoft Academic Search

The conductance of multiwalled carbon nanotubes (MWNTs) was found to be quantized. The experimental method involved measuring the conductance of nanotubes by re- placing the tip of a scanning probe microscope with a nanotube fiber, which could be lowered into a liquid metal to establish a gentle electrical contact with a nanotube at the tip of the fiber. The conductance

Stefan Frank; Philippe Poncharal; Z. L. Wang; Walt A. de Heer

1998-01-01

60

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

NASA Astrophysics Data System (ADS)

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

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

2009-07-01

61

Effect of magnetic field on Mott's variable-range hopping parameters in multiwall carbon nanotube mat.  

PubMed

We report the temperature and magnetic field dependence of the conductivity of multiwall carbon nanotube mat in the temperature range 1.4-150 K and in magnetic fields up to 10 T. It is observed that charge transport in this system is governed by Mott’s variable-range hopping of three-dimensional type in the higher temperature range and two-dimensional type in the lower temperature range. Mott’s various parameters, such as localization length, hopping length, hopping energy and density of states at the Fermi level are deduced from the variable-range hopping fit. The resistance of the sample decreases with the magnetic field applied in the direction of tube axis of the nanotubes. The magnetic field gives rise to delocalization of states with the well-known consequence of a decrease in Mott’s T0 parameter in variable-range hopping. The application of magnetic field lowers the crossover temperature at which three-dimensional variable-range hopping turns to two-dimensional variable-range hopping. The conductivity on the lower temperature side is governed by the weak localization giving rise to positive magnetoconductance. Finally, a magnetic field-temperature diagram is proposed showing different regions for different kinds of transport mechanism. PMID:22627115

Arya, Ved Prakash; Prasad, V; Kumar, P S Anil

2012-06-20

62

Direct observation of band-gap closure for a semiconducting carbon nanotube in a large parallel magnetic field.  

PubMed

We have investigated the magnetoconductance of semiconducting carbon nanotubes (CNTs) in pulsed, parallel magnetic fields up to 60 T, and report the direct observation of the predicted band-gap closure and the reopening of the gap under variation of the applied magnetic field. We also highlight the important influence of mechanical strain on the magnetoconductance of the CNTs. PMID:21405643

Jhang, S H; Marga?ska, M; Skourski, Y; Preusche, D; Grifoni, M; Wosnitza, J; Strunk, C

2011-03-01

63

Nanopumping using carbon nanotubes.  

SciTech Connect

A new 'nanopumping' effect consisting of the activation of an axial gas flow inside a carbon nanotube by producing Rayleigh traveling waves on the nanotube surface is predicted. The driving force for the new effect is the friction between the gas particles and the nanotube walls. A molecular dynamics simulation of the new effect was carried out showing macroscopic flows of atomic and molecular hydrogen and helium gases in a carbon nanotube.

Insepov, Z.; Wolf, D.; Hassanein, A.; Mathematics and Computer Science; INL

2006-01-01

64

Nanopumping using carbon nanotubes.  

PubMed

A new "nanopumping" effect consisting of the activation of an axial gas flow inside a carbon nanotube by producing Rayleigh traveling waves on the nanotube surface is predicted. The driving force for the new effect is the friction between the gas particles and the nanotube walls. A molecular dynamics simulation of the new effect was carried out showing macroscopic flows of atomic and molecular hydrogen and helium gases in a carbon nanotube. PMID:16967997

Insepov, Zeke; Wolf, Dieter; Hassanein, Ahmed

2006-09-01

65

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

PubMed Central

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

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

2013-01-01

66

Temperature Influence on the Morphology and the Magnetic Properties of Vertically Aligned Fe?filled Carbon Nanotubes  

Microsoft Academic Search

Arrays of vertically aligned Fe?filled multi?wall carbon nanotubes (MWNTs) on oxidized silicon substrates were prepared by pyrolysis of ferrocene in a dual furnace system and characterized by electron microscopy and magnetometry measurement. The effect of the growth temperature on both the filled nanotube morphology and their magnetic behavior was studied. Increasing the growth temperature in the range of 845–1035°C the

D. Elefant; M. Hofmann; A. Leonhardt; I. Mönch; M. Ritschel; B. Büchner

2007-01-01

67

The novel synthesis of magnetically chitosan/carbon nanotube composites and their catalytic applications.  

PubMed

Chitosan-modified magnetic carbon nanotubes (CS-MCNTs) were synthesized and were investigated by FT-IR, EDX, FE-SEM, elemental analysis, XRD, VSM and TGA. In order to synthesize the CS-MCNTs composites, Fe3O4 decorated carbon nanotubes (CNTs-Fe3O4) were modified with a silica layer by the ammonia-catalysed hydrolysis of tetraethyl orthosilicate (CNTs-Fe3O4@SiO2). Then, CS-MCNTs were successfully grafted on the surface of CNTs-Fe3O4@SiO2via a suspension cross-linking method. The CS-MCNT was found to be an excellent heterogeneous catalyst for the synthesis of 1,4-dihydropyridines (DHPs). The attractive advantages of the present process include short reaction times, milder and cleaner conditions, higher purity and yields, easy isolation of products, easier work-up procedure and lower generation of waste or pollutions. This catalyst was easily separated by an external magnet and the recovered catalyst was reused several times without any significant loss of activity. A combination of the advantages of CNTs, chitosan and magnetic nanoparticles provides an important methodology for carrying out catalytic transformations. Therefore, this method provides a green and much improved protocol over the existing methods. PMID:25597431

Zarnegar, Zohre; Safari, Javad

2015-04-01

68

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

NASA Astrophysics Data System (ADS)

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

Ghasemi, Ali

2013-03-01

69

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

PubMed

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. PMID:25408246

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

2015-01-01

70

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

71

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

SciTech Connect

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

Huang, P; Schwegler, E; Galli, G

2008-11-14

72

Functionalized Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

73

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

74

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

75

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

PubMed

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

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

2014-11-25

76

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

NASA Astrophysics Data System (ADS)

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.

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

77

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

PubMed

Sulfur (S) is introduced as an additive in the growth atmosphere of carbon nanotubes (CNTs) in the range of 940-1020°C. CNT products with distorted sidewalls can be obtained by S-assisted growth. Moreover, many fascinating CNT structures can also be found in samples grown with S addition, such as bamboo-like CNTs, twisted CNTs, arborization-like CNTs, and bead-like CNTs. Compared with CNTs grown without S, more nitrogen-doping content is achieved in CNTs with S addition, which is beneficial for the properties and applications of nitrogen-doped CNTs. In addition, S can also enhance the encapsulation of ferromagnetic materials and thus improve the soft magnetic properties of CNTs, which is favorable to the applications of CNTs in the electromagnetic wave-absorbing and magnetic data storage areas. PMID:21711610

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

2011-01-01

78

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

79

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

PubMed Central

Sulfur (S) is introduced as an additive in the growth atmosphere of carbon nanotubes (CNTs) in the range of 940-1020°C. CNT products with distorted sidewalls can be obtained by S-assisted growth. Moreover, many fascinating CNT structures can also be found in samples grown with S addition, such as bamboo-like CNTs, twisted CNTs, arborization-like CNTs, and bead-like CNTs. Compared with CNTs grown without S, more nitrogen-doping content is achieved in CNTs with S addition, which is beneficial for the properties and applications of nitrogen-doped CNTs. In addition, S can also enhance the encapsulation of ferromagnetic materials and thus improve the soft magnetic properties of CNTs, which is favorable to the applications of CNTs in the electromagnetic wave-absorbing and magnetic data storage areas. PMID:21711610

2011-01-01

80

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

81

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

82

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

PubMed Central

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

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

2012-01-01

83

Introduction to Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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

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

84

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

PubMed

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

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

2014-05-15

85

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

Microsoft Academic Search

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

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

2006-01-01

86

Introduction to Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes are remarkable objects that look set to revolutionize the technological landscape in the near future. Tomorrow's society will be shaped by nanotube applications, just as silicon-based technologies dominate society today. Space elevators tethered by the strongest of cables; hydrogen-powered vehicles; artificial muscles: these are just a few of the technological marvels that may be made possible by the emerging science of carbon nanotubes.

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

87

Carbon nanotubes for nanorobotics  

Microsoft Academic Search

The well-defined geometry, exceptional mechanical properties, and extraordinary electrical characteristics of carbon nanotubes qualify them for structuring nanoelectronic circuits, nanoelectromechanical systems, and nanorobotic systems. Relative displacements between the atomically smooth, nested shells in multiwalled carbon nanotubes can be used as robust nanoscale motion enabling mechanisms for applications such as bearings, switches, gigahertz oscillators, shuttles, memories, syringes, and actuators. The hollow

Lixin Dong; Arunkumar Subramanian; Bradley J. Nelson

2007-01-01

88

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

89

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

NASA Astrophysics Data System (ADS)

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

Theres Baby, Tessy; Sundara, Ramaprabhu

2011-09-01

90

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

E-print Network

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

In, Hyun Jin

2010-01-01

91

Nanopumping Using Carbon Nanotubes  

Microsoft Academic Search

ABSTRACT A new,“nanopumping” effect consisting of the activation of an axial gas flow inside a carbon,nanotube,by producing,Rayleigh traveling waves on the nanotube,surface is predicted. The driving force for the new,effect is the friction between,the gas particles and the nanotube,walls. A molecular,dynamics,simulation of the new,effect was,carried out showing,macroscopic,flows of atomic and molecular,hydrogen,and helium gases,in a carbon,nanotube. Actuation of a fluid flow

Zeke Insepov; Dieter Wolf; Ahmed Hassanein

2006-01-01

92

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

93

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

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

94

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

95

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

SciTech Connect

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

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

2014-06-21

96

Numerical Characterization of Magnetically Aligned Multiwalled Carbon Nanotube-Fe3O4 Nanoparticle Complex.  

PubMed

Alignment states of one-dimensional multiwalled carbon nanotubes containing various contents of zero-dimensional ferriferrous oxide nanoparticles (MWCNT-Fe3O4) were numerically characterized. MWCNT-Fe3O4 complexes were successfully prepared via in situ surface-initiated atom transfer radical polymerization, followed by a coprecipitation process. The complexes showed strong magnetism, which endowed them with the ability to be aligned under the action of an external magnetic field. The intensity of the magnetic field, loading content of Fe3O4 nanoparticles, and viscosity of dispersing medium, however, all had substantial effects on the alignment degree. To evaluate the alignment effectively and quantitatively, an orientation tensor description based on marking the direction of a single MWCNT in a selected region of optical images was employed. The results showed that MWCNT-Fe3O4 complex containing 26 wt % of Fe3O4 nanoparticles achieved a desirable alignment in deionized water under a magnetic field intensity of 0.10 T. Accordingly, epoxy composites reinforced with such aligned MWCNT-Fe3O4 complexes displayed 12.3 and 10.9% enhancement in tensile strength and modulus, as well as 8.9 and 6.1% enhancement in flexural strength and modulus, respectively. PMID:25597815

Jia, Xiaolong; Li, Wusheng; Xu, Xianjuan; Li, Wenbin; Cai, Qing; Yang, Xiaoping

2015-02-11

97

Adsorption and Kinetic Study on Sn2+ Removal Using Modified Carbon Nanotube and Magnetic Biochar  

NASA Astrophysics Data System (ADS)

The effectiveness of stannum (Sn2+) removal from aqueous solution by using magnetic biochar and functionalized multiwalled carbon nanotube (FMWCNT) was investigated. The effect of various factors, namely pH, adsorbent dosage, agitation speed and contact time was statistically studied through analysis of variance (ANOVA). Statistical analysis revealed that the optimum conditions for the highest removal of Sn2+ are at pH 5, dosage 0.1 g with agitation speed and time of 100 rpm and 90 min, respectively. At the initial concentration of 0.1 mg/L, the removal efficiency of Sn2+ using FMWCNTs was 93% and 85% with magnetic biochar. The Langmuir and Freundlich constant for both FMWCNTs and magnetic biochar were 13.397 L/mg, 18.634 L/mg and 17.719 L/mg, 25.204 L/mg, respectively. Hence, results prove that FMWCNTs are a better adsorbent with a higher adsorption capacity compared to magnetic biochar. Adsorption kinetic obeyed pseudo-second-order.

Mubarak, N. M.; Ruthiraan, M.; Sahu, J. N.; Abdullah, E. C.; Jayakumar, N. S.; Sajuni, N. R.; Tan, J.

2013-02-01

98

Carbon Nanotubes in Neuroscience  

PubMed Central

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

Malarkey, Erik B.

2010-01-01

99

Phase composition and magnetic characteristics of Fe-filled multi-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The work addresses the correlation between the phase composition and the magnetic characteristics of aligned Fe-filled multi-walled carbon nanotubes (Fe-MWCNTs) grown by pyrolysis of ferrocene on oxidized Si substrates. In a combinatorial approach we exploited the extremely high gradients of the technological parameters temperature and ferrocene flow across the surface of a substrate positioned close to the reactor wall to obtain a large variation in the structural and magnetic properties of the Fe-MWCNTs. In this way, we established several clear correlations between the Fe-filling phase composition and the overall magnetic characteristics of the aligned Fe-MWCNTs. The ?-Fe rich samples, which possess a more ordered graphitic sheet structure, a higher degree of preferred crystalline orientation of the metal filling and much larger metal crystallites in comparison with the carbide-rich samples, show a much stronger magnetic anisotropy with easy axis perpendicular to the substrate and unusually high values of the coercive field Hc and the saturation field Hs. The changes in the measured saturation magnetisation Ms and the Hc values correlate well with the variation of the ?-Fe content and the filling crystallinity. A special annealing treatment of the samples causes a distinct increase of the ?-Fe quantity and an increase of the measured average grain size. The respective magnetic characteristics show a significant increase of the overall magnetic moment and decrease of the coercive field. The correlation between the structural and the magnetic characteristics of the annealed samples matches quite well the respective correlations in the case of as-deposited samples.

Groudeva-Zotova, S.; Kozhuharova, R.; Elefant, D.; Mühl, T.; Schneider, C. M.; Mönch, I.

2006-11-01

100

Carbon nanotube electronics  

Microsoft Academic Search

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

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

2003-01-01

101

Sequential coating of magnetic carbonyliron particles with polystyrene and multiwalled carbon nanotubes and its effect on their magnetorheology.  

PubMed

A two-step process for the sequential coating of magnetic carbonyliron (CI) particles with polystyrene (PS) and multiwalled carbon nanotubes (MWCNTs) was used to improve the sedimentation stability of micrometer-sized magnetic CI particles for magnetorheological (MR) applications under an applied magnetic field. The CI particles were initially coated with nanosized PS beads using an in situ dispersion polymerization method and then wrapped with a dense MWCNT nest through a solvent-casting method in a water/oil emulsion system. The morphology, MR performance, and sedimentation stability of the synthesized magnetic composite particles were examined. The composite particles showed enhanced MR characteristics and dispersion stability. PMID:20356220

Fang, Fei Fei; Choi, Hyoung Jin; Seo, Yongsok

2010-01-01

102

Carbon nanotubes: Fibrillar pharmacology  

NASA Astrophysics Data System (ADS)

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

Kostarelos, Kostas

2010-10-01

103

Transport in Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

104

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

PubMed Central

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

2014-01-01

105

Magnetic properties and phase transitions of gadolinium-infused carbon nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotube (CNT)/metal-cluster-based composites are envisioned as new materials that possess unique electronic properties which may be utilized in a variety of future applications. Superparamagnetic behavior was reported for CNTs with Gd ions introduced into the CNT openings by internal loading with an aqueous GdCl3 chemical process. In the current work, the magnetic properties of the CNT/Gd composites were obtained by the joining and annealing of Gd metal and CNTs at 850 °C for 48 h. Energy dispersive X-ray analysis shows the presence of Gd intermingled with the CNT walls with maximum and average Gd concentrations of about 20% and 4% (by weight), respectively. The Gd clusters have a non-uniform distribution and are mostly concentrated at the ends of the CNTs. A ferromagnetic-type transition at TC ˜ 320 K, accompanied by jump like change in magnetization and temperature hysteresis typical for the temperature induced first order phase transitions has been observed by magnetization measurements. It was found that Gd infused into the CNTs by the annealing results in a first order paramagnetic-ferromagnetic transition at TC = 320 K.

Quetz, Abdiel; Dubenko, Igor; Samanta, Tapas; Vinson, Herbert; Talapatra, Saikat; Ali, Naushad; Stadler, Shane

2013-05-01

106

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

107

Functionalization of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

These project will explore the functionalization of carbon nanotubes via the formation of molecular complexes with perylene diimide based systems. It is anticipated that these complexes would be soluble in organic solvent and enable the homogenous dispersion of carbon nanotubes in polymer films. Molecular complexes will be prepared and characterized using standard spectroscopic and thermal analytical techniques. Polymer films will be prepared with these complexes and their properties (electrical and thermal conductivity, mechanical properties, stability) evaluated.

Webber, Stephen E.

2003-01-01

108

Functionalization of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

109

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

110

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

SciTech Connect

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

Karli?i?, Danilo; Caji?, Milan [Mathematical Institute of the SASA, Kneza Mihaila 36, Belgrade 11001 (Serbia); Murmu, Tony [School of Engineering, University of the West of Scotland, Paisley PA12BE (United Kingdom); Kozi?, Predrag [Faculty of Mechanical Engineering, University of Niš, A. Medvedeva 14, 18000 Niš (Serbia); Adhikari, Sondipon [College of Engineering, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom)

2014-06-21

111

Sensor applications of carbon nanotubes  

E-print Network

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

Rushfeldt, Scott I

2005-01-01

112

An RF circuit model for carbon nanotubes  

Microsoft Academic Search

We develop an RF circuit model for single walled carbon nanotubes for both dc and capacitively contacted geometries. By modeling the nanotube as a nanotransmission line with distributed kinetic and magnetic inductance as well as distributed quantum and electrostatic capacitance, we calculate the complex, frequency dependent impedance for a variety of measurement geometries. Exciting voltage waves on the nanotransmission line

P. J. Burke

2003-01-01

113

Carbon nanotube array based sensor  

DOEpatents

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.

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

2005-09-20

114

Templated Growth of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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.

Siochik Emilie J. (Inventor)

2007-01-01

115

Carbon Nanotubes for Data Processing  

E-print Network

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

Joselevich, Ernesto

116

Raman spectroscopy of carbon nanotubes  

Microsoft Academic Search

The use of Raman spectroscopy to reveal the remarkable structure and the unusual electronic and phonon properties of single wall carbon nanotubes (SWNTs) is reviewed comprehensively. The various types of Raman scattering processes relevant to carbon nanotubes are reviewed, and the theoretical foundations for these topics are presented. The most common experimental techniques used to probe carbon nanotubes are summarized,

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

2005-01-01

117

Raman Scattering in Carbon Nanotubes  

E-print Network

Raman Scattering in Carbon Nanotubes Ms.sc. Thesis Faculty of Science University of Copenhagen 2003;#12;Abstract The phonon properties of single-wall carbon nanotubes (SWNT's) are investi- gated using Raman. Employing a tight binding method the electronic structure of single-wall carbon nanotubes is explored the

Nygård, Jesper

118

Carbon Nanotube Linear Bearing Nanoswitches  

E-print Network

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

Bockrath, Marc

119

Investigating Chemical Disorder Strength in Carbon Nanotubes : Magnetic Tuning of Quantum Transport Regimes  

Microsoft Academic Search

A quantitative analysis of the relationship between energy-dependant elastic mean free path and localization length has been done, and an external magnetic eld applied perpendiculary to the nanotube axis is shown to induce a shift in energies of quasibound states, a phe- nomenon that results in giant magnetoconductance uctuations under Fermi level shift.

R emi Avriller; S. Latil; F. Triozon; X. Blase; S. Roche

120

Artifact properties of carbon nanotube yarn electrode in magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

121

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

122

Structural dependence of carbon nanotube orbital magnetic susceptibility: tight binding calculations  

NASA Astrophysics Data System (ADS)

Recent ab initio calculations of the orbital magnetic susceptibility anisotropies in carbon nanotubes (CNTs) have shown large, systematic differences among zigzag CNTs of similar diameters [1]. We theoretically investigate the origin of these trends by applying the zone-folding method within the nearest-neighbor tight-binding approximation to all chiral and achiral semiconducting CNT species with diameters between 0.6 nm and 1.7 nm. Our results show qualitative agreement with the ``mod 1'' and ``mod 2'' trends of the ab initio theory and additionally distinguish between trigonal warping and curvature-related effects as physical reasons for the predicted species-dependent spread. Our calculations show (2n+m) patterns similar to those in a recent, experimentally-motivated ``fan-out'' diagram [2] and can be likewise fit to an analytical four-term chirality expansion. [1] Marques, M. A. L.; d'Avezac, M. & Mauri, F., Phys. Rev. B, 2006, 73, 125433 [2] Torrens, O. N.; Milkie, D. E.; Ban, H. Y.; Zheng, M.; Onoa, G. B.; Gierke, T. D. & Kikkawa, J. M., J. Am. Chem. Soc., 2007, 129, 252-253

Torrens, O. N.; Kikkawa, J. M.

2008-03-01

123

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

124

Boron Nitride Nanotubes (BNNTs) vs Carbon Nanotubes (CNTs)  

E-print Network

Nanotube Boron Nitride Nanotubes (BNNTs) vs Carbon Nanotubes (CNTs) Thang Pham Physics 141A #12;Outline 1. Crystal structures of Nanotubes (NTs) 2. Physics Properties: BNNTs vs CNTs 3. What make BNNTs

Budker, Dmitry

125

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

126

Polymer Nanocomposites Containing Carbon Nanotubes  

Microsoft Academic Search

We review the present state of polymer nanocomposites research in which the fillers are single- wall or multiwall carbon nanotubes. By way of background we provide a brief synopsis about carbon nanotube materials and their suspensions. We summarize and critique various nanotube\\/polymer composite fabrication methods including solution mixing, melt mixing, and in situ polymerization with a particular emphasis on evaluating

Mohammad Moniruzzaman; Karen I. Winey

2006-01-01

127

Carbon nanotubes: The solar approach  

Microsoft Academic Search

Using the same experimental set-up as for the solar production of fullerenes, we can also produce carbon nanotubes by direct vaporization of a mixture of powdered carbon and catalyst (Co, Ni, Y). The structure of the nanotubes is strongly dependent on the experimental conditions (pressure and flow rate of Ar gas) and we can obtain either multi-walled nanotubes or ropes

D. Laplaze; P. Bernier; W. K. Maser; G. Flamant; T. Guillard; A. Loiseau

1998-01-01

128

Electrical models for vertical carbon nanotube capacitors  

Microsoft Academic Search

We present electrical models for a carbon nanotube capacitor with high capacitance per unit area. We begin by introducing the concept of using vertically grown carbon nanotubes to develop a carbon nanotube capacitor. Three potential structures of the carbon nanotube capacitor are presented. We determine the capacitance per unit area for each structure. The carbon nanotube capacitor structures exhibit capacitances

Mark M. Budnik; Eric W. Johnson; Joshua D. Wood

2008-01-01

129

Carbon nanotube filters  

NASA Astrophysics Data System (ADS)

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.

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

2004-09-01

130

Effect of magnetic field on Mott’s variable-range hopping parameters in multiwall carbon nanotube mat  

NASA Astrophysics Data System (ADS)

We report the temperature and magnetic field dependence of the conductivity of multiwall carbon nanotube mat in the temperature range 1.4-150 K and in magnetic fields up to 10 T. It is observed that charge transport in this system is governed by Mott’s variable-range hopping of three-dimensional type in the higher temperature range and two-dimensional type in the lower temperature range. Mott’s various parameters, such as localization length, hopping length, hopping energy and density of states at the Fermi level are deduced from the variable-range hopping fit. The resistance of the sample decreases with the magnetic field applied in the direction of tube axis of the nanotubes. The magnetic field gives rise to delocalization of states with the well-known consequence of a decrease in Mott’s T0 parameter in variable-range hopping. The application of magnetic field lowers the crossover temperature at which three-dimensional variable-range hopping turns to two-dimensional variable-range hopping. The conductivity on the lower temperature side is governed by the weak localization giving rise to positive magnetoconductance. Finally, a magnetic field-temperature diagram is proposed showing different regions for different kinds of transport mechanism.

Arya, Ved Prakash; Prasad, V.; Kumar, P. S. Anil

2012-06-01

131

Separation and enrichment of six indicator polychlorinated biphenyls from real waters using a novel magnetic multiwalled carbon nanotube composite absorbent.  

PubMed

A novel and effective magnetic multiwalled carbon nanotube composite for the separation and enrichment of polychlorinated biphenyls was developed. Fe3 O4 @SiO2 core-shell structured nanoparticles were first synthesized, then the poly(sodium 4-styrenesulfonate) was laid on its surface to prepare the polyanionic magnetic nanoparticles. The above materials were then grafted with polycationic multiwalled carbon nanotubes, which were modified by polydiallyl dimethyl ammonium chloride through the layer-by-layer self-assembly approach. Its performance was tested by magnetic solid-phase extraction and gas chromatography with mass spectrometry for the determination of six kinds of indicator polychlorinated biphenyls in water samples. Under optimal conditions, the spiked recoveries of several real samples for six kinds of polychlorinated biphenyls (PCB28, PCB52, PCB101, PCB138, PCB153, PCB180) were in the range of 73.4-99.5% with relative standard deviations varying from 1.5 to 8.4%. All target compounds showed good linearities in the tested range with correlation coefficients higher than 0.9993. The limits of quantification for six kinds of indicator polychlorinated biphenyls were between 0.018 and 0.039 ng/mL. The proposed method was successfully applied to analyze polychlorinated biphenyls in real water samples. Satisfactory results were obtained using the effective magnetic absorbent. PMID:25556922

Zhang, Jiabin; Gan, Ning; Pan, Muyun; Lin, Saichai; Cao, Yuting; Wu, Dazhen; Long, Nengbing

2015-03-01

132

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

Microsoft Academic Search

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

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

2007-01-01

133

Nuclear Magnetism and Electronic Order in 13 C Nanotubes  

E-print Network

Nuclear Magnetism and Electronic Order in 13 C Nanotubes Bernd Braunecker,1 Pascal Simon,1 carbon nanotubes grown entirely from 13C form an ideal system to study the effect of electron interaction carbon nanotubes (SWNTs) elec- tron correlations are even more important. For metallic (armchair) SWNT

Braunecker, Bernd

134

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

PubMed Central

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

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

2014-01-01

135

The Toxicology of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

136

Carbon Nanotube Purification and Functionalization  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

137

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

PubMed

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

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

2015-01-01

138

Carbon nanotubes on a substrate  

DOEpatents

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

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

2002-03-26

139

Chirality dependence of dipole matrix element of carbon nanotubes in axial magnetic field: A third neighbor tight binding approach  

NASA Astrophysics Data System (ADS)

We have studied the electronic structure and dipole matrix element, D, of carbon nanotubes (CNTs) under magnetic field, using the third nearest neighbor tight binding model. It is shown that the 1NN and 3NN-TB band structures show differences such as the spacing and mixing of neighbor subbands. Applying the magnetic field leads to breaking the degeneracy behavior in the D transitions and creates new allowed transitions corresponding to the band modifications. It is found that |D| is proportional to the inverse tube radius and chiral angle. Our numerical results show that amount of filed induced splitting for the first optical peak is proportional to the magnetic field by the splitting rate ?11. It is shown that ?11 changes linearly and parabolicly with the chiral angle and radius, respectively.

Chegel, Raad; Behzad, Somayeh

2014-02-01

140

Method of manufacturing carbon nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

141

Carbon nanotube suspensions, dispersions, & composites  

Microsoft Academic Search

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

Trevor John Simmons

2008-01-01

142

Carbon nanotube IR detectors (SV)  

SciTech Connect

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.

Leonard, F. L.

2012-03-01

143

Carbon nanotube network varactor  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

144

Carbon nanotube network varactor.  

PubMed

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

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

2015-01-30

145

CCMR: Carbon Nanotube Polymer Hybrids: Polymerization of Functionalized Carbon Nanotubes  

NSDL National Science Digital Library

This project was to functionalize carbon nanotubes, and polymerize from their surfaces to increase solubility, decrease bundling, and form polymer-nanotube hybrid materials. Single wall carbon nanotubes (SWNT) were the main focus of this project. Functionalization was accomplished by attaching nitroxide-mediated radical polymerization (NMP) initiator molecules to SWNT. Both covalent and non-covalent attachment methods were used for initiator attachment. Polymerization of styrene was used to test polymerizations off SWNT. Nitroxide exchange reactions were also explored.

Peterson, Joseph

2004-08-17

146

Carbon Nanotubes for Polymer Photovoltaics  

Microsoft Academic Search

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

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

2007-01-01

147

Carbon Nanotube Nucleated Polymer Crystallization  

Microsoft Academic Search

Crystallinity studies were performed on carbon nanotube?doped Poly(m?phenylenevinylene?co?2,5?dioctyloxy?p?phenylenevinylene) (PmPV) and Poly (vinyl alcohol) (PVOH). Differential Scanning Calorimetry (DSC) of the composites verified that carbon nanotubes nucleate polymer crystallization.

K. P. Ryan; M. Cadek; A. Drury; M. Ruether; W. J. Blau; J. N. Coleman

2005-01-01

148

CARBON NANOTUBES AS MULTIPOLLUTANT SORBENTS  

EPA Science Inventory

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

149

Carbon nanotube Archimedes screws.  

PubMed

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

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

2010-12-28

150

Experimental Quantum Transport in Carbon Nanotubes  

E-print Network

Experimental Quantum Transport in Carbon Nanotubes: Josephson Quantum Dot Junctions and Double of Copenhagen Denmark June 2007 #12;ii Experimental Quantum Transport in Carbon Nanotubes: Josephson Quantum Dot into two parts/fields: Carbon nanotube Josephson quantum dot Junctions and Carbon nanotube double quantum

Nygård, Jesper

151

Carbon nanotubes as liquid crystals.  

PubMed

Carbon nanotubes are the best of known materials with a combination of excellent mechanical, electronic, and thermal properties. To fully exploit individual nanotube properties for various applications, the grand challenge is to fabricate macroscopic ordered nanotube assemblies. Liquid-crystalline behavior of the nanotubes provides a unique opportunity toward reaching this challenge. In this Review, the recent developments in this area are critically reviewed by discussing the strategies for fabricating liquid-crystalline phases, addressing the solution properties of liquid-crystalline suspensions, and exploiting the practical techniques of liquid-crystal routes to prepare macroscopic nanotube fibers and films. PMID:18752206

Zhang, Shanju; Kumar, Satish

2008-09-01

152

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

PubMed

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

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

2011-09-01

153

Studies of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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.

Caneba, Gerard T.

2005-01-01

154

Functionalization of carbon nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

155

Functionalization of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

156

Carbon Nanotube Interconnect  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

157

Carbon-Nanotube Optoelectronics  

Microsoft Academic Search

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

Phaedon Avouris; Marcus Freitag; Vasili Perebeinos

158

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

PubMed

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. PMID:25649901

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

2015-03-01

159

Influence of AC magnetic field on phonon vibrations of superparamagnetic cluster sitting at tip end of ultra-long carbon nanotube  

NASA Astrophysics Data System (ADS)

Ultra-long carbon nanotube (CNT) growth with Fe cluster sitting at tip end under AC magnetic field as a function of magnetic field, susceptibility of catalyst, number of cluster atoms, reaction time, reaction temperature, diameter of the carbon nanotube and damping factor of the system in chemical vapor deposition is investigated using a theoretical analysis on the phonon vibration of the system. Results show that CNT length in the presence of field increases. Also there is an optimum temperature which is reduced by increasing of magnetic field. Finally, it is shown that in the presence of magnetic field, Fe is a better catalyst than Ni because of its higher superparamagnetic susceptibility. Results of the theory are very useful for experimental works.

Saeidi, Mohammadreza; Vaezzadeh, Majid; Mansouri, Mozhgan

2012-04-01

160

Carbon nanotube array actuators  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

161

Method for synthesizing carbon nanotubes  

DOEpatents

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.

Fan, Hongyou

2012-09-04

162

Nanoscale atomic waveguides with suspended carbon nanotubes  

E-print Network

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

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

2005-11-23

163

Nanotechnology: Spinning continuous carbon nanotube yarns  

Microsoft Academic Search

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

Kaili Jiang; Qunqing Li; Shoushan Fan

2002-01-01

164

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

PubMed

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

Ma, Guifu; Chen, Ligang

2014-02-14

165

Carbon nanotubes in hyperthermia therapy  

PubMed Central

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

Singh, Ravi; Torti, Suzy V.

2013-01-01

166

Carbon nanotubes as vaccine scaffolds  

PubMed Central

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

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

2013-01-01

167

Method for producing carbon nanotubes  

DOEpatents

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

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

2006-02-14

168

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)

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.

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

2012-09-01

169

All About Chlorinated Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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.

Erbahar, Dogan; Berber, Savas

2011-03-01

170

RELATIVE CHIRAL ABUNDANCES OF CARBON NANOTUBES DETERMINED BYRELATIVE CHIRAL ABUNDANCES OF CARBON NANOTUBES DETERMINED BYRELATIVE CHIRAL ABUNDANCES OF CARBON NANOTUBES DETERMINED BYRELATIVE CHIRAL ABUNDANCES OF CARBON NANOTUBES DETERMINED BY RESONANT RAMAN  

E-print Network

RELATIVE CHIRAL ABUNDANCES OF CARBON NANOTUBES DETERMINED BYRELATIVE CHIRAL ABUNDANCES OF CARBON NANOTUBES DETERMINED BYRELATIVE CHIRAL ABUNDANCES OF CARBON NANOTUBES DETERMINED BYRELATIVE CHIRAL ABUNDANCES OF CARBON NANOTUBES DETERMINED BY RESONANT RAMAN SPECTROSCOPY USING A TUNABLE DYE LASERRESONANT

Mellor-Crummey, John

171

cover image although carbon nanotubes are  

E-print Network

cover image although carbon nanotubes are not superconductors, they can carry supercurrents injected from superconducting contacts. analysis of the tunnelling spectra of a nanotube connecting two ocean Andreas Trabesinger 940 hybrid superconducting devices: Bound in a nanotube Wolfgang Belzig 941

Loss, Daniel

172

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

PubMed

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

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

2015-01-01

173

Nanocrystalline diamond from carbon nanotubes  

NASA Astrophysics Data System (ADS)

Structural phase transformation from multiwalled carbon nanotubes to nanocrystalline diamond by hydrogen plasma post-treatment was carried out. Ultrahigh equivalent diamond nucleation density above 1011 nuclei/cm2 was easily obtained. The diamond formation and growth mechanism was proposed to be the consequence of the formation of sp3 bonded amorphous carbon clusters. The hydrogen chemisorption on curved graphite network and the energy deposited on the carbon nanotubes by continuous impingement of activated molecular or atomic hydrogen are responsible for the formation of amorphous carbon matrix. Diamond nucleates and grows in the way similar to that of diamond chemical vapor deposition processes on amorphous carbon films.

Sun, L. T.; Gong, J. L.; Zhu, Z. Y.; Zhu, D. Z.; He, S. X.; Wang, Z. X.; Chen, Y.; Hu, G.

2004-04-01

174

Selective functionalization of carbon nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

175

Overview of Nanotechnology: Carbon Nanotubes  

NSDL National Science Digital Library

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

176

PECVD Growth of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

177

Dispersible carbon nanotubes.  

PubMed

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

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

2014-01-27

178

Cantilevered carbon nanotube hygrometer  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

179

Carbon nanotube biconvex microcavities  

NASA Astrophysics Data System (ADS)

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 ?m tall MWCNTs were patterned as biconvex microcavities, which were separated by 10 ?m 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.

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

2015-03-01

180

Carbon nanotube terahertz detector.  

PubMed

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

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

2014-07-01

181

Carbon Nanotube Electron Gun  

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

182

Carbon nanotube electron gun  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

183

Supersymmetric twisting of carbon nanotubes  

E-print Network

We construct exactly solvable models of twisted carbon nanotubes via supersymmetry, by applying the matrix Darboux transformation. We derive the Green's function for these systems and compute the local density of states. Explicit examples of twisted carbon nanotubes are produced, where the back-scattering is suppressed and bound states are present. We find that the local density of states decreases in the regions where the bound states are localized. Dependence of bound-state energies on the asymptotic twist of the nanotubes is determined. We also show that each of the constructed unextended first order matrix systems possesses a proper nonlinear hidden supersymmetric structure with a nontrivial grading operator.

Vit Jakubsky; Mikhail S. Plyushchay

2012-02-28

184

Carbon nanotube filters  

Microsoft Academic Search

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

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

2004-01-01

185

Carbon nanotube composites P. J. F. Harris*  

E-print Network

Carbon nanotube composites P. J. F. Harris* Carbon nanotubes are molecular-scale tubes of graphitic carbon with outstanding properties. They are among the stiffest and strongest fibres known, with Young. There is currently great interest in exploiting these properties by incorporating carbon nanotubes into some form

Harris, Peter J F

186

Scanning Probe Microscopy Studies of Carbon Nanotubes  

E-print Network

Scanning Probe Microscopy Studies of Carbon Nanotubes Teri Wang Odom1 , Jason H. Hafner1 nanotubes, and moreover, the fabrica- tion and utilization of nanotubes as novel tips for probe microscopy relationship between Single-Walled Carbon Nanotube (SWNT) atomic structure and electronic properties, (2

Odom, Teri W.

187

Electromechanical Properties of Multiwall Carbon Nanotubes  

E-print Network

Electromechanical Properties of Multiwall Carbon Nanotubes A. Zettl and John Cumings Department properties of multiwall carbon nanotubes using transport measurements performed in-situ inside a high through the nanotubes and the failure modes for nanotube "burnout" examined . In a second set

Zettl, Alex

188

Connecting carbon nanotubes using Sn.  

PubMed

Process of Sn coating on mutiwalled carbon nanotubes (MWCNT) and formation of interconnections among nanotubes are studied using high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDX). Surface oxidation of nanotubes during heating with HNO3 prior to the SnCl2 treatment and the bonding between functional groups and Sn are found to be responsible for the coating and its stability. Open nanotubes are filled as well as coated during tin chloride treatment. Coating and filling are converted into the coatings on the inner as well as outer walls of the nanotubes during reduction with H2/N2. EDX studies show the formation of intermetallic compounds e.g., Cu6Sn5 and Cu3Sn at the joints between nanotubes. Formation of intermetallic compounds is supposed to be responsible for providing the required strength for bending and twisting of nanotubes joining of nanotubes. Paper presents a detailed mechanism of coating and filling processes, and interconnections among nanotubes. PMID:23882800

Mittal, Jagjiwan; Lin, Kwang Lung

2013-08-01

189

Carbon Nanotubes for Polymer Photovoltaics  

NASA Astrophysics Data System (ADS)

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.

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

2007-03-01

190

Carbon nanotubes Growth of Single-Walled Carbon Nanotubes from Sharp  

E-print Network

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

Nordlund, Kai

191

Carbon Nanotube Purification  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

192

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

PubMed

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

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

2014-02-01

193

Mechanics of deformation of carbon nanotubes  

E-print Network

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

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

2005-01-01

194

Semiconducting single wall carbon nanotubes inverstigated by  

E-print Network

Semiconducting single wall carbon nanotubes inverstigated by photoconductivity Electronique Fondamentale, University of Paris Sud 11, Orsay, France 3: Research Center for Photovoltaics Using semiconducting single wall carbon nanotubes with well defined chiral index (n,m), the photo

Maruyama, Shigeo

195

Torsional instability of chiral carbon nanotubes  

E-print Network

In this work we investigate the presence of a torsional instability in single-wall carbon nanotubes which causes small diameter chiral carbon nanotubes to show natural torsion. To obtain insight into the nature of this ...

Dresselhaus, Mildred

196

Doctoral Thesis Cavity QED with carbon nanotubes  

E-print Network

Doctoral Thesis Cavity QED with carbon nanotubes We are inviting applications for a PhD position- diameter single-walled carbon nanotubes has demonstrated that this system can show exceptional fluorescence

Hänsch, Theodor W.

197

Mechanical energy storage in carbon nanotube springs  

E-print Network

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

Hill, Frances Ann

2011-01-01

198

Carbon Nanotubes Hybrid Hydrogels in Drug Delivery: A Perspective Review  

PubMed Central

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

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

2014-01-01

199

Copper nanocluster diffusion in carbon nanotube  

Microsoft Academic Search

The diffusion of copper nanocluster in carbon nanotube was investigated using a classical molecular dynamics simulation and three empirical potential functions. The results indicated a growth mechanism of the copper-filled ultra-thin carbon nanotubes: the copper nanoclusters inserted into carbon nanotubes swiftly migrate along the tube axis, and then the copper nanowires grow in the ultra-thin carbon nanotubes. Periodic energy barriers

Ho Jung Hwang; Oh-Keun Kwon; Jeong Won Kang

2004-01-01

200

Structural flexibility of carbon nanotubes  

Microsoft Academic Search

We report high resolution electron microscope (HREM) observations and atomistic simulations of the bending of single and multi-walled carbon nanotubes under mechanical duress. Single and multiple kinks are observed at high bending angles. Their occurrence is quantitatively explained by the simulations, which use a realistic many-body potential for the carbon atoms. We show that the bending is fully reversible up

Sumio Iijima; Charles Brabec; Amitesh Maiti; Jerzy Bernholc

1996-01-01

201

Carbon Nanotube Based Molecular Electronics  

NASA Technical Reports Server (NTRS)

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

Srivastava, Deepak; Saini, Subhash; Menon, Madhu

1998-01-01

202

Multiscale Modeling with Carbon Nanotubes  

SciTech Connect

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

Maiti, A

2006-02-21

203

Carbon Nanotubes as Cooper Pair Beam Dissertation  

E-print Network

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

Paris-Sud XI, Université de

204

Coulomb Drag in Multiwall Carbon Nanotubes  

E-print Network

Coulomb Drag in Multiwall Carbon Nanotubes Master Thesis in Physics Anders Mathias Lunde Niels Bohr the band structure of carbon nanotubes. For discussions about the experimental possibilities I will like drag and how is it studied? . . . . . . . . . . . 2 1.3 What is a Carbon nanotube

Nygård, Jesper

205

Reassessing Fast Water Transport Through Carbon Nanotubes  

E-print Network

Reassessing Fast Water Transport Through Carbon Nanotubes John A. Thomas and Alan J. H. Mc carbon nanotubes (CNTs) with diameters ranging from 1.66 to 4.99 nm is examined using molecular dynamics rates of pressure-driven water through membranes of 1.6 and 7 nm diameter carbon nanotubes (CNTs

McGaughey, Alan

206

Dispersions of Carbon nanotubes in Polymer Matrices  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

207

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

PubMed

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

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

2014-08-15

208

CaH2-assisted low temperature synthesis of metallic magnetic nanoparticle-loaded multiwalled carbon nanotubes.  

PubMed

We studied synthesis of Ni or Fe nanoparticle-loaded multiwalled carbon nanotubes (MWCNTs) by pyrolyzing metal organic salts with CaH2, a very strong reductant. The use of CaH2 lowered the formation temperature of MWCNTs down to 400 °C without the use of toxic halogen-containing precursors and assistance of plasma. PMID:24837804

Seinberg, Liis; Yamamoto, Shinpei; Tsujimoto, Masahiko; Kobayashi, Yoji; Takano, Mikio; Kageyama, Hiroshi

2014-07-01

209

Structural transformations of carbon chains inside nanotubes  

SciTech Connect

In situ aberration-corrected high-resolution transmission electron microscopy is used to examine the structural transformations of carbon chains that occur in the interior region of carbon nanotubes. We find electron-beam irradiation leads to the formation of two-dimensional carbon structures that are freely mobile inside the nanotube. The inner diameter of the nanotube influences the structural transformations of the carbon chains. As the diameter of the nanotube increases, electron-beam irradiation leads to curling of the chains and eventually the formation of closed looped structures. The closed looped structures evolve into spherical fullerenelike structures that exhibit translational motion inside the nanotubes and also coalesce to form larger nanotube structures. These results demonstrate the use of carbon nanotubes as test tubes for growing small carbon nanotubes within the interior by using only electron-beam irradiation at 80 kV.

Warner, Jamie H. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Ruemmeli, Mark H.; Bachmatiuk, Alicja; Buechner, Bernd [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany)

2010-04-15

210

Carbon nanotube-polymer composite actuators  

DOEpatents

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

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

2008-04-22

211

Carbon Nanotubes and Graphene Manish Chhowalla  

E-print Network

Carbon Nanotubes and Graphene Manish Chhowalla (manish1@rci.rutgers.edu) http://nanotubes gives the Energy Gap for the nanotubes: Odom, Teri; et. al.Nature 391 p59 1998 #12;Zig-zag Armchair Filled circles denote n-m divisible by 3 which give metallic nanotubes. #12;Dresselhaus, NT05 Tutorial

Glashausser, Charles

212

Thermoelectric power in ultrathin films, quantum wires and carbon nanotubes under classically large magnetic field: Simplified theory and relative comparison  

NASA Astrophysics Data System (ADS)

We study the thermoelectric power under classically large magnetic field (TPM) in ultrathin films (UFs), quantum wires (QWs) of non-linear optical materials on the basis of a newly formulated electron dispersion law considering the anisotropies of the effective electron masses, the spin-orbit splitting constants and the presence of the crystal field splitting within the framework of k· p formalism. The results of quantum confined III-V compounds form the special cases of our generalized analysis. The TPM has also been studied for quantum confined II-VI, stressed materials, bismuth and carbon nanotubes (CNs) on the basis of respective dispersion relations. It is found taking quantum confined CdGeAs 2, InAs, InSb, CdS, stressed n-InSb and Bi that the TPM increases with increasing film thickness and decreasing electron statistics exhibiting quantized nature for all types of quantum confinement. The TPM in CNs exhibits oscillatory dependence with increasing carrier concentration and the signature of the entirely different types of quantum systems are evident from the plots. Besides, under certain special conditions, all the results for all the materials gets simplified to the well-known expression of the TPM for non-degenerate materials having parabolic energy bands, leading to the compatibility test.

Kumar, A.; Choudhury, S.; Saha, S.; Pahari, S.; De, D.; Bhattacharya, S.; Ghatak, K. P.

2010-01-01

213

All carbon nanotubes are not created equal  

SciTech Connect

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.

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

2010-01-01

214

Viscoelasticity in carbon nanotube composites.  

PubMed

Polymer composites reinforced by carbon nanotubes have been extensively researched for their strength and stiffness properties. Unless the interface is carefully engineered, poor load transfer between nanotubes (in bundles) and between nanotubes and surrounding polymer chains may result in interfacial slippage and reduced performance. Interfacial shear, although detrimental to high stiffness and strength, could result in very high mechanical damping, which is an important attribute in many commercial applications. We previously reported evidence of damping in nanocomposites by measuring the modal response (at resonance) of cantilevered beams with embedded nanocomposite films. Here we carry out direct shear testing of epoxy thin films containing dense packing of multiwalled carbon nanotube fillers and report strong viscoelastic behaviour with up to 1,400% increase in loss factor (damping ratio) of the baseline epoxy. The great improvement in damping was achieved without sacrificing the mechanical strength and stiffness of the polymer, and with minimal weight penalty. Based on the interfacial shear stress (approximately 0.5 MPa) at which the loss modulus increases sharply for our system, we conclude that the damping is related to frictional energy dissipation during interfacial sliding at the large, spatially distributed, nanotube-nanotube interfaces. PMID:15640807

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

2005-02-01

215

Supersymmetric twisting of carbon nanotubes  

E-print Network

We construct exactly solvable models of twisted carbon nanotubes via supersymmetry, by applying the matrix Darboux transformation. We derive the Green's function for these systems and compute the local density of states (LDOS). Explicit examples of twisted carbon nanotubes are produced, where the back-scattering is suppressed and bound states are present. We find that LDOS decreases in the regions where the bound states are localized. We also show that each of the constructed unextended first order matrix systems possesses a proper nonlinear hidden supersymmetric structure with a nontrivial grading operator.

Jakubsky, Vit

2012-01-01

216

CMOS Integrated Carbon Nanotube Sensor  

SciTech Connect

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

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

2009-05-23

217

Gears Based on Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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 use of coolant gases. For a given application, the gears would work well at temperatures below the critical range, provided that the rotational energy was less than the energy required to tilt the teeth through an angle of 20 . The predominant mechanism of gear failure would be slippage caused by tilting of teeth. Gears would resume functioning if the slipping gears were decelerated sufficiently.

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

2005-01-01

218

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

E-print Network

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

Joselevich, Ernesto

219

The fabrication of single-walled carbon nanotube/polyelectrolyte multilayer composites by layer-by-layer assembly and magnetic field assisted alignment  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotube (SWNT)/polymer composites are widely studied because of their potential for high mechanical performance and multifunctional applications. In order to realize highly ordered multilayer nanostructures, we combined the layer-by-layer (LBL) assembly method with magnetic force-induced alignment to fabricate SWNT/poly(ethylamine) (PEI) multilayer composites. The SWNTs were functionalized with the anionic surfactant sodium dodecylbenzenesulfonate (NaDDBS) to realize negative charge at pH>7, while the PEI is positively charged at pH<7. The LBL method is based on the electrostatic absorption between the charged SWNTs and PEI resin to form multilayer composites on a solid substrate polydimethylsiloxane. Since the fabricated thickness of each SWNT-NaDDBS/PEI bilayer is uniform (~150 nm), the multilayer film thickness can be strictly controlled via the number of deposition cycles. A high magnetic field (8.5 Tesla) was used to align the SWNTs during the LBL process. The resultant LBL composite samples demonstrated high SWNT loading of approximately 50 wt% and uniform distribution of SWNTs in the multilayer structures, which was verified using a quartz crystal microbalance. Good alignment was also realized and observed through using high magnetic fields to align the nanotubes during the LBL deposition process. The results indicate that the LBL/magnetic alignment approach has potential for fabricating nanotube composites with highly ordered nanostructures for multifunctional materials and device applications.

Tian, Ying; Park, Jin Gyu; Cheng, Qunfeng; Liang, Zhiyong; Zhang, Chuck; Wang, Ben

2009-08-01

220

Effect of Carbon Nanotubes on Mammalian Cells  

NASA Astrophysics Data System (ADS)

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.

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

2010-03-01

221

Synthesis of carbon nanotubes and nanotube forests on copper catalyst  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

222

Analysis of carbon nanotubes using nanoelectromechanical oscillators  

NASA Astrophysics Data System (ADS)

In this thesis the thermo-mechanical properties of single-walled carbon nanotubes are investigated utilizing carbon nanotube based nanoelectromechanical oscillators. These resonator devices are highly sensitive to changes in tension on the carbon nanotube. In Chapters 4 the coefficient of thermal expansion of an individual single-walled carbon nanotube is measured in the range 4K - 475K. Experimental observation of this parameter has not been reported before this work and the calculations give different results depending on the models used. The observed negative thermal expansion is attributed to the free configurational space around the carbon atoms of the nanotube. When the nanotube is cooled, the entropy of the system is lowered by expanding the volume of the nanotube through various changes in the structure like pinching twisting or bending. The minimum of the coefficient of thermal expansion is measured as -4.5 ppm·K-1 at 100K. The coefficient of thermal expansion remains negative throughout the entire range. The mechanical response of carbon nanotube electromechanical oscillators at elevated temperatures is studied in Chapter 5. The weak interaction forces between the carbon nanotube and underlying platinum electrodes limit the performance of carbon nanotube electromechanical oscillators, where the devices are built as described in Chapter 3. Van der Waals bond between the carbon nanotube and the platinum electrode weaken as the temperature increases. At a critical temperature the nanotube delaminates from the surface completely and a sudden drop is observed in the mechanical resonance frequency of the oscillator. Using the results obtained, the clamping force between the carbon nanotube and the underlying platinum electrode is measured to be around 3 pN. The small value obtained for the clamping force shows that quality factor of carbon nanotube electromechanical resonators is affected by the clamping efficiency of the nanotube ends. Carbon nanotubes have unique electron ransport properties at high bias voltages. Due to their one dimensional nature, scattering of electrons by phonon are highly nonlinear. At low bias voltages (across the nanotube) phonon scattering is suppressed and the electrons exhibit ballistic transport. At higher bias voltages optical phonon scattering dominates, and subsequently nanotubes heat suddenly. In Chapter 6, the heating of nanotubes is probed using the mechanical vibrations of a carbon nanotube based nanoelectromechanical oscillator. Since the substrate temperature is constant the change in mechanical resonance frequency is attributed to the contraction of the nanotube due to its negative thermal expansion. The bias voltage, at which the mechanical resonance shows a sudden drop, corresponds to experimentally observed optical phonon emission onset voltage for single-walled carbon nanotubes.

Aykol, Mehmet

223

Conductance Oscillations in Squashed Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

224

Controlled Placement of Individual Carbon Nanotubes  

E-print Network

Controlled Placement of Individual Carbon Nanotubes Xue Ming Henry Huang, Robert Caldwell, Limin and the technology of carbon nanotubes is the controlled assembly of devices. Here, we report a technique that allows us to place a nanotube with the desired properties in a predetermined location by direct mechanical

Hone, James

225

Extraordinary Mobility in Semiconducting Carbon Nanotubes  

E-print Network

Extraordinary Mobility in Semiconducting Carbon Nanotubes T. Du1rkop, S. A. Getty, Enrique Cobas, 2003 ABSTRACT Semiconducting carbon nanotube transistors with channel lengths exceeding 300 microns. These values exceed those for all known semiconductors, which bodes well for application of nanotubes in high

Fuhrer, Michael S

226

Ferromagnetically Contacted Single-Wall Carbon Nanotubes  

E-print Network

Ferromagnetically Contacted Single-Wall Carbon Nanotubes Ane Jensen Ph.d. Thesis Department of Copenhagen April 2003 #12;#12;Ferromagnetically Contacted Single-Wall Carbon Nanotubes Abstract Ferromagnetic nanotubes (SWNTs), with the purpose of study spin-polarized transport under the unique conditions of- fered

Nygård, Jesper

227

Carbon nanotubes with ferromagnetic and semiconducting contacts  

E-print Network

Carbon nanotubes with ferromagnetic and semiconducting contacts Ph.D. Thesis Jonas Rahlf Hauptmann nanotubes with ferromagnetic and semiconducting contacts Ph.D. Thesis c Jonas Rahlf Hauptmann 2008 e Institute and Nano-Science Centre. The aim was to study carbon nanotubes with different type of contacts

Nygård, Jesper

228

Junction array carbon nanotube bolometer  

NASA Astrophysics Data System (ADS)

Vertically aligned arrays of multi-walled carbon nanotubes (MWNT forests) irradiated with low-intensity near-infrared laser exhibited bolometric response that became significant with decreasing temperature down from room to about 84 K. High responsivity of 42 V/W with signal bandwidth of about 2600 Hz was observed in the region with a surprisingly small temperature coefficient of resistance. This fact along with peculiar current dependences of material differential photoresistance can be explained by lifting Coulomb blockade in carbon nanotube junctions irradiated with light. A combination of significant bolometric response and nonlinear electrical transport are believed to be characteristic features of the nanostructured junction array system. Investigated material also revealed quite substantial noise with equivalent power of 3 * 10-6 WHz-1/2 that can be reduced by optimization of nanotube junction network in the forest structure.

Kozlov, Mikhail E.

2013-04-01

229

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

PubMed

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

Du, Zhuo; Liu, Miao; Li, Gongke

2013-10-01

230

Reversal modes in magnetic nanotubes  

E-print Network

The magnetic switching of ferromagnetic nanotubes is investigated as a function of their geometry. Two independent methods are used: Numerical simulations and analytical calculations. It is found that for long tubes the reversal of magnetization is achieved by two mechanism: The propagation of a transverse or a vortex domain wall depending on the internal and external radii of the tube.

P. Landeros; S. Allende; J. Escrig; E. Salcedo; D. Altbir; E. E. Vogel

2006-11-08

231

Carbon Nanotubes and Human Cells?  

ERIC Educational Resources Information Center

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

King, G. Angela

2005-01-01

232

Terahertz detection and carbon nanotubes  

ScienceCinema

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

Leonard, Francois

2014-06-13

233

A carbon nanotube capacitor structure  

Microsoft Academic Search

In this abstract, we present additional details on a new capacitor, CNCAP (carbon nanotube capacitor), compare it to existing integrated circuit capacitor technologies, and address its manufacturability. Properties of metallic, single wall CNTs (large surface area and relatively low resistance) allow for the creation of a very high density capacitor structure. In the CNCAP, each CNT electrode is surrounded by

J. D. Wood; M. M. Budnik

2007-01-01

234

Purification procedure of carbon nanotubes  

Microsoft Academic Search

We report results on purification and characterization of single wall carbon nanotubes prepared by the electric arc method. The process consists of a chemical treatment based on a reflux with nitric acid followed by successive filtration steps (tangential flow and frontal filtration) of a suspension of the raw material. The effects of each step are analysed by SEM and TEM.

L. Vaccarini; C. Goze; R. Aznar; V. Micholet; C. Journet; P. Dernier

1999-01-01

235

Terahertz detection and carbon nanotubes  

SciTech Connect

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

Leonard, Francois

2014-06-11

236

Transparent, Conductive Carbon Nanotube Films  

Microsoft Academic Search

We describe a simple process for the fabrication of ultrathin, transparent, optically homogeneous, electrically conducting films of pure single-walled carbon nanotubes and the transfer of those films to various substrates. For equivalent sheet resistance, the films exhibit optical transmittance comparable to that of commercial indium tin oxide in the visible spectrum, but far superior transmittance in the technologically relevant 2-

Zhuangchun Wu; Zhihong Chen; Xu Du; Jonathan M. Logan; Jennifer Sippel; Maria Nikolou; Katalin Kamaras; John R. Reynolds; David B. Tanner; Arthur F. Hebard; Andrew G. Rinzler

2004-01-01

237

Adsorption and migration of carbon adatoms on zigzag carbon nanotubes  

E-print Network

Adsorption and migration of carbon adatoms on zigzag carbon nanotubes A.V. Krasheninnikov a,*, K of single-walled zigzag carbon nanotubes. We demonstrate that the adatoms form strong covalent bonds and migration barrier depend on the nanotube diameter and chirality. The migration barriers, being in the range

Krasheninnikov, Arkady V.

238

Redox sorting of carbon nanotubes.  

PubMed

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

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

2015-03-11

239

A carbon nanotube bearing and Stodola rotor  

E-print Network

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

Cook, Eugene Hightower

2008-01-01

240

Carbon nanotubes : synthesis, characterization, and applications  

E-print Network

and mechanical characterization. Journal of Physics D:and mechanical properties of nanotubes. Applied Physics A,Mechanical Behavior of Ultra-long Multi-walled Carbon Nanotube Mats”, Journal of Applied Physics,

Deck, Christian Peter

2009-01-01

241

Nanocrystalline diamond from carbon nanotubes  

Microsoft Academic Search

Structural phase transformation from multiwalled carbon nanotubes to nanocrystalline diamond by hydrogen plasma post-treatment was carried out. Ultrahigh equivalent diamond nucleation density above 1011 nuclei\\/cm2 was easily obtained. The diamond formation and growth mechanism was proposed to be the consequence of the formation of sp3 bonded amorphous carbon clusters. The hydrogen chemisorption on curved graphite network and the energy deposited

L. T. Sun; J. L. Gong; Z. Y. Zhu; D. Z. Zhu; S. X. He; Z. X. Wang; Y. Chen; G. Hu

2004-01-01

242

Adsorption to carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

Kahng, Yung Ho

243

From carbon nanotubes to carbon atomic chains  

NASA Astrophysics Data System (ADS)

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.

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

2010-10-01

244

Optical conductivity of carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

Mousavi, Hamze

2012-06-01

245

Individual carbon nanotubes as molecular quantum wires  

NASA Astrophysics Data System (ADS)

I will give an overview of our recent results obtained on quantum electronic transport through individual single-wall carbon nanotubes. These experimental results show that carbon nanotubes can be metallic quantum wires even at the single-molecular level. Nanotubes are deposited onto nanofabricated metal contacts. AFM images show individual micron-long nanotubes with a diameter of about 1 nm. Low-temperature measurements( S. J. Tans, M. H. Devoret, H. Dai, A. Thess, R. E. Smalley, L. J. Geerligs, and C. Dekker, Nature 386, 474 (1997)) indicate that Coulomb charging results in a gap around zero bias voltage. Zero-bias conduction can be restored by varying the electrostatic potential of the tube by means of a third electrode that acts as a gate. The measurements indicate resonant tunneling through well-separated discrete electron states that extend over very long distances. The energy separation between the states (0.4 meV) is consistent with tight-binding predictions for a particle-in-a-box where the 3 micron-long nanotube is the electron box. Data in a magnetic field show shifting of states due to the Zeeman effect, and indicate deviations from standard Fermi liquid behavior.(S. J. Tans et al, to be published) Experiments on tubes over multiple (up to 7) nanoelectrodes indicate that a certain class of nanotubes can behave as a chain of quantum wires connected in series.(A. Bezryadin, A. R. M. Verschueren, S. J. Tans, R. E. Smalley, and C. Dekker, submitted to Phys. Rev. Lett.) STM imaging and spectroscopy on single-wall nanotubes allows to make the correlation between the atomic and electronic structure of nanotubes.(J.W.G.Wildoer, L.C. Venema, A.G. Rinzler, R.E. Smalley, and C. Dekker, Nature, aimed for publication in Januari 1998) Recent transport experiments on individual nanotubes demonstrate that we can build a single-molecule field-effect transistor that operates at room temperature.(S. J. Tans et al, to be published ) footnotetext[0]email: dekker@qt.tn.tudelft.nl Work done in collaboration with S.J. Tans, A. Bezryadin, M.H. Devoret, A.R.M. Verschueren, R.J.A. Groeneveld, L.J. Geerligs, A. Thess, H. Dai, A.R. Rinzler, and R.E. Smalley

Dekker, Cees

1998-03-01

246

Rapid magnetic solid-phase extraction based on magnetic multiwalled carbon nanotubes for the determination of polycyclic aromatic hydrocarbons in edible oils.  

PubMed

In this study, magnetic multiwalled carbon nanotubes were fabricated by a simple method and applied to magnetic solid-phase extraction (MSPE) of eight heavy molecular weight polycyclic aromatic hydrocarbons (PAHs) including chrysene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, dibenzo[a,h]anthracene and benzo[g,h,i]perylene from edible oil samples. Several parameters affecting the extraction efficiency were investigated, including the type and volume of desorption solvent, extraction and desorption time, washing solution and the amount of sorbent. Under the optimized conditions, a simple and effective method for the determination of PAHs in edible oils was developed by coupling with gas chromatography-mass spectrometry (GC-MS). The whole pretreatment process was rapid, and it can be accomplished within 10 min. The limits of quantitation for the target PAHs were found to be 0.34-2.9 ng/g. The recoveries in oil sample were in the range 87.8-122.3% with the RSDs less than 6.8% (intraday) and 9.6% (interday). This method was successfully applied to the analysis of PAHs in seven kinds of edible oils from local markets. PMID:22103676

Zhao, Qin; Wei, Fang; Luo, Yan-Bo; Ding, Jun; Xiao, Neng; Feng, Yu-Qi

2011-12-28

247

Carbon-Nanotube Schottky Diodes  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

248

Aharonov-Bohm conductance modulation in ballistic carbon nanotubes.  

PubMed

We report on magnetoconductance experiments in ballistic multiwalled carbon nanotubes threaded by magnetic fields as large as 55 T. In the high temperature regime (100 K), giant modulations of the conductance, mediated by the Fermi level location, are unveiled. The experimental data are consistently analyzed in terms of the field-dependent density of states of the external shell that modulates the injection properties at the electrode-nanotube interface, and the resulting linear conductance. This is the first unambiguous experimental evidence of Aharonov-Bohm effect in clean multiwalled carbon nanotubes. PMID:17501520

Lassagne, B; Cleuziou, J-P; Nanot, S; Escoffier, W; Avriller, R; Roche, S; Forró, L; Raquet, B; Broto, J-M

2007-04-27

249

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

PubMed

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

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

2015-02-01

250

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)

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.

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

2015-02-01

251

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

NASA Technical Reports Server (NTRS)

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.

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

2014-01-01

252

Alignment of Carbon Nanotubes Comprising Magnetically Sensitive Metal Oxides in Nanofluids  

NASA Technical Reports Server (NTRS)

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.

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

2014-01-01

253

Magnetic structure and anisotropy of fcc-iron nanoclusters trapped in carbon nanotube  

Microsoft Academic Search

Mossbauer spectroscopy combined with SQUID magnetometry was carried out in an applied magnetic field of up to 1 T at temperatures between 5 K and 300 K to investigate the atomic-level magnetic structure of the fcc-Fe nanoparticles. The corner Fe atoms in the fcc unit cell are in a high spin state, while the face-centered Fe atoms are in a

M. Shima; S. K. Nayak; S. Nasu; P. M. Ajayan

2005-01-01

254

Carbon nanotubes based ultrasonic microtransducers for durability monitoring Aligned carbon nanotubes based ultrasonic microtransducers  

E-print Network

Carbon nanotubes based ultrasonic microtransducers for durability monitoring 1 Aligned carbon nanotubes based ultrasonic microtransducers for durability monitoring in civil engineering B Lebental1,5 , P single-walled carbon nanotubes (SWNT). Such sensors are meant to be embedded in large number within

Paris-Sud XI, Université de

255

Method of making carbon nanotube composite materials  

DOEpatents

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

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

2014-05-20

256

Nanoscale Fluorescence Microscopy Using Carbon Nanotubes  

Microsoft Academic Search

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

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

2008-01-01

257

Carbon nanotube biocompatibility with cardiac muscle cells  

Microsoft Academic Search

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

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

2006-01-01

258

Catalytic synthesis and purification of carbon nanotubes  

Microsoft Academic Search

Carbon deposition on a catalyst surface during decomposition of different carbon-containing compounds can be used for the synthesis of carbon nanotubes of graphitic structure. Different supported transition metal oxides were found to be active in the production of these nanotubes. The selectivity of the catalytic method is significantly higher than that of either the arc discharge or the flame method.

K. Hernadi; A. Fonseca; J. B. Nagy; D. Bernaerts; J. Riga; A. Lucas

1996-01-01

259

Carbon Nanotubes: Synthesis, Properties, and Applications  

Microsoft Academic Search

This brief review presents a comprehensive outline of the present research status on the fast moving carbon nanotube (CNT) field. It covers a short introduction to the relation between carbon nanotubes, graphite, and other forms of carbon and explains in detail the structure of CNTs. The electronic, electrical, and mechanical properties of CNTs, as well as the most widely used

Enkeleda Dervishi; Zhongrui Li; Yang Xu; Viney Saini; Alexandru R. Biris; Dan Lupu; Alexandru S. Biris

2009-01-01

260

Carbon nanotube devices: Sorting, Assembling, Characterizing  

NASA Astrophysics Data System (ADS)

Carbon nanotubes have been studied extensively over the last decade. Various exceptional properties have been revealed which still drive the vision about using carbon nanotube in future electronics, for instance as molecular nanoscale transistors or electromigration resistant interconnects. For many years a major obstacle was the inability to grow nanotubes with defined dimensions (length, diameter) and electronic properties (metallic,semiconducting). Recently those problems have been solved to a large extent by advanced sorting techniques. Today the challenge is to assemble nanotubes devices with defined properties to form a complex circuitry. As progress is made in making highly-integrated nanotube device arrays new characterization techniques have to be developed which allow testing large number of devices within an acceptable time. Along this line I will report on the state-of-the-art of sorting of carbon nanotube, as a base for nanotube device fabrication [1]. I will then explain our strategy to assemble high-density arrays of nanotube devices [2] and discuss a new characterization technique for nanotube devices [3]. Finally I will introduce a novel device engineering tool [4]. [4pt] [1] R. Krupke et al., ``Separation techniques for carbon nanotubes'' in Chemistry of Carbon Nanotubes, p.129-139, American Scientific Publishers 2008[0pt] [2] A. Vijayaraghavan et al., ``Ultra-Large-Scale Directed Assembly of Single-Walled Carbon Nanotube Devices'', Nano Lett. 7 (2007) 1556-1560[0pt] [3] A. Vijayaraghavan et al., ``Imaging Electronic Structure of Carbon Nanotubes by Voltage-Contrast Scanning Electron Microscopy'', Nano Resarch 1 (2008) 321-332[0pt] [4] C. W. Marquardt et al., ``Reversible metal-insulator transitions in metallic single-walled carbon nanotubes'', Nano Lett. 9 (2008) 2767-2772

Krupke, Ralph

2009-03-01

261

Phonons and Thermal Properties of Carbon Nanotubes  

E-print Network

Phonons and Thermal Properties of Carbon Nanotubes James Hone Department of Physics, University nanotubes display a wide range of behaviors which are related both to their graphitic nature and their unique struc- ture and size. The specific heat of individual nanotubes should be similar to that of two

Hone, James

262

Electromechanical Properties of Multiwall Carbon Nanotubes  

Microsoft Academic Search

We examine electrical and coupled electromechanical properties of multiwall carbon nanotubes using transport measurements performed in-situ inside a high resolution transmission electron microscope (TEM). In one experiment, large electrical currents are passed through the nanotubes and the failure modes for nanotube \\

A. Zettl; John Cumings

2003-01-01

263

Raman spectroscopy of metallic carbon nanotubes  

E-print Network

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

Farhat, Hootan

2010-01-01

264

Carbon Nanotubes: Molecular Electronic Components  

NASA Technical Reports Server (NTRS)

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

Srivastava, Deepak; Saini, Subhash; Menon, Madhu

1997-01-01

265

Torsional carbon nanotube artificial muscles.  

PubMed

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. PMID:21998253

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

2011-10-28

266

Magnetic force microscopy measurements in external magnetic fields-comparison between coated probes and an iron filled carbon nanotube probe  

Microsoft Academic Search

We performed magnetic force microscopy (MFM) measurements in external magnetic fields parallel to the sample plane to qualitatively study their effect on the magnetization of different kinds of MFM probes. As a test structure we used an array of rectangular ferromagnetic thin film elements aligned with the external magnetic field direction. MFM images were taken while the field was increased

F. Wolny; T. Mühl; U. Weissker; A. Leonhardt; U. Wolff; D. Givord; B. Büchner

2010-01-01

267

Rabi Waves in Carbon Nanotubes  

E-print Network

QED-model for the multichain qubit system with interactions of qubits and chains between themselves on the example of the system of $\\sigma$-polarons in carbon zigzag nanotubes, interacting with quantized EM-field, is considered analytically. The possibility of experimental detection of Rabi waves in conventional stationary optical experiments for any quasi-1D system with strong electron-photon interaction is predicted.

Alla Dovlatova; Dmitry Yearchuck

2010-09-08

268

Membranes of vertically aligned superlong carbon nanotubes.  

PubMed

In the present work, we have developed a simple but effective method to prepare superlong vertically aligned carbon nanotubes (SLVA-CNT) and epoxy composite membranes, and we have demonstrated that various liquids, including water, hexane, and dodecane, can effectively pass through the SLVA-CNT membranes. These results were confirmed by molecular dynamics simulations. While the mechanical densification was used to further enhance the flow transport through the SLVA-CNT membranes, we developed in this study a magnetic-nanoparticle switching system to turn on and off the flow through the nanotube membrane by simply applying an alternating voltage. The methodologies developed in this study should have a significant implication to the development of various smart membranes for advanced intelligent systems. PMID:21657212

Du, Feng; Qu, Liangti; Xia, Zhenhai; Feng, Lianfang; Dai, Liming

2011-07-01

269

Carbon nanotube-based biosensors  

NASA Astrophysics Data System (ADS)

An easy and rapid detection of hazardous compounds is crucial for making on-the-spot irreversible decisions at airport security gates, luggage storage rooms, and other crowded public places, such as stadia, concert halls, etc. In the present study we carried out a preliminary investigation into the possibility of utilizing as advanced nano-biosensors a mutant form of the bovine odorant-binding protein (bOBP) immobilized onto carbon nanotubes. In particular, after immobilization of the protein on the carbon nanotubes we developed a competitive resonance energy transfer (RET) assay between the protein tryptophan residues located at the positions 17 and 133 (W17 and W133) and the 1-amino-anthracene (AMA), a molecule that fits in the binding site of bOBP. The bOBP-AMA complex emitted light in the visible region upon excitation of the Trp donors. However, the addition of an odorant molecule to the bOBP-AMA complex displaced AMA from the binding site making the carbon nanotubes colorless. The results presented in this work are very promising for the realization of a color on/ color off b-OBP-based biosensor for the initial indication of hazardous compounds in the environment.

Ramoni, Roberto; Staiano, Maria; Bellucci, Stefano; Grycznyski, Ignacy; Grycznyski, Zygmunt; Crescenzo, Roberta; Iozzino, Luisa; Bharill, Shashank; Conti, Virna; Grolli, Stefano; D'Auria, Sabato

2008-11-01

270

LDRD final report on carbon nanotube composites  

SciTech Connect

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

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

1997-04-01

271

Logic Circuits with Carbon Nanotube Transistors  

Microsoft Academic Search

We demonstrate logic circuits with field-effect transistors based on single carbon nanotubes. Our device layout features local gates that provide excellent capacitive coupling between the gate and nanotube, enabling strong electrostatic doping of the nanotube from p-doping to n-doping and the study of the nonconventional long-range screening of charge along the one-dimensional nanotubes. The transistors show favorable device characteristics such

Adrian Bachtold; Peter Hadley; Takeshi Nakanishi; Cees Dekker

2001-01-01

272

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

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?g/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?g/kg. The proposed method is reliable and robust, having an excellent potential for the analysis of trans-resveratrol in edible oils. PMID:25704710

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

2015-07-01

273

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

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

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

2014-08-15

274

EVIDENCE FOR ROOM-TEMPERATURE SUPERCONDUCTIVITY IN CARBON NANOTUBES  

Microsoft Academic Search

In this article, we provide electrical, magnetic, tunnelin g, and Raman spectro- scopic evidence for room-temperature superconductivity in carbon nanotubes. Elec- trical measurements indicate that the superconducting transition temperatures in car- bon nanotubes can vary from 0.44 K to 750 K. The temperature dependencies of the resistive transitions agree quantitatively with the well-established Langer- Ambegaokar-McCumber-Halperin (LAMH) theory for the resistive

Guo-meng Zhao

275

Nanotube electronics: Large-scale assembly of carbon nanotubes  

Microsoft Academic Search

Nanoscale electronic devices made from carbon nanotubes, such as transistors and sensors, are much smaller and more versatile than those that rely on conventional microelectronic chips, but their development for mass production has been thwarted by difficulties in aligning and integrating the millions of nanotubes required. Inspired by biomolecular self-assembly processes, we have created chemically functionalized patterns on a surface,

Saleem G. Rao; Ling Huang; Wahyu Setyawan; Seunghun Hong

2003-01-01

276

Plasticity and Kinky Chemistry of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

Srivastava, Deepak; Dzegilenko, Fedor

2000-01-01

277

Carbon Nanotube Superconducting Quantum Interference Device.  

NASA Astrophysics Data System (ADS)

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 ?-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.

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

2007-03-01

278

Magnetic solid-phase extraction based on magnetic multi-walled carbon nanotubes for the determination of polycyclic aromatic hydrocarbons in grilled meat samples.  

PubMed

A sensitive and reliable method for determination of polycyclic aromatic hydrocarbons (PAHs) in grilled meat samples was developed and validated. The method is based on magnetic solid phase extraction (MSPE) and GC-MS analysis. Magnetic carbon nanotubes (MCNTs) which have excellent adsorption capabilities, were used as adsorbent to extract PAHs, an important class of carcinogens, from meat samples. To obtain the best extraction yields, the influencing factors, including primary extraction conditions, the amount of adsorbent, adsorption and desorption time, salt addition and desorption solvent were investigated in detail. Under optimized conditions, the LODs and LOQs achieved were in the range of 0.035-0.100 and 0.075-0.200 µg Kg(-1) respectively. The calibration curves were linear (r(2) ? 0.988) over the concentration ranges from 0.100 µg Kg(-1) to 250 µg Kg(-1) The relative standard deviations (RSDs) obtained by carrying out intra- and inter-day precision studies were less than 13.7% and 13.9%, respectively which confirms reproducibility of the method. In addition, the recoveries of analyzed PAHs ranged from 81.3% to 96.7% with the RSDs less than 12.7 %. Finally, the established MSPE-GC-MS method was successfully applied to determine PAHs in charcoal grilled/barbecued meat samples. benzo[a]anthracene, benzo[b]fluoranthene, Benzo[a]pyrene and chrysene were detected in beef, lamb and chicken meat samples with the mean cumulative concentration of 4.000, 3.414 and 0.931 µg Kg(-1) respectively. Taken together, the MSPE-GC-MS method developed in current study provides a new option for the determination of PAHs in grilled/barbecued meat samples. PMID:24054688

Moazzen, Mojtaba; Ahmadkhaniha, Reza; Gorji, Mohamad Es'haghi; Yunesian, Masud; Rastkari, Noushin

2013-10-15

279

Les nanotubes de carbone Pascale Launois  

E-print Network

1 Les nanotubes de carbone Pascale Launois http://www.lps.u-psud.fr/ launois@lps.u-psud.fr COURS : historique nanotubes de carbone II. Structure et caractérisation III. Méthodes et mécanismes de synthèse IV.4-100 nm S. Iijima Longueur ~ m (jusqu'au cm) UNIDIMENSIONNEL SWNT & MWNT Single & Multi-Wall Nanotube I.3

Paris-Sud 11, Université de

280

CARBON NANOTUBES: PROPERTIES AND APPLICATIONS  

SciTech Connect

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 the new materials, highly porous carbide-derived carbons (CDC), is the subject of an add-on to this grant awarded to myself and Taner Yildirim (NIST). Results from the add-on led eventually to a new 3-year award DE-FG02-08ER46522 “From Fundamental Understanding to Predicting New Nanomaterials for High Capacity Hydrogen Storage”, $1000K, (05/31/2008 - 05/01/2011) with Taner Yildirim and myself as co-PI’s.

Fischer, John, E.

2009-07-24

281

Specific surface area of carbon nanotubes and bundles of carbon nanotubes  

Microsoft Academic Search

The theoretical external specific surface area of single- and multi-walled carbon nanotubes and of carbon nanotube bundles is calculated as a function of their characteristics (diameter, number of walls, number of nanotubes in a bundle). The results are reported in diagrams and tables useful to correlate the microscopic characteristics and the specific surface area of samples. The calculated values are

A. Peigney; Ch. Laurent; E. Flahaut; R. R. Bacsa; A. Rousset

2001-01-01

282

Magnetic carbon.  

PubMed

The discovery of nanostructured forms of molecular carbon has led to renewed interest in the varied properties of this element. Both graphite and C60 can be electron-doped by alkali metals to become superconducting; transition temperatures of up to 52 K have been attained by field-induced hole-doping of C60 (ref. 2). Recent experiments and theoretical studies have suggested that electronic instabilities in pure graphite may give rise to superconducting and ferromagnetic properties, even at room temperature. Here we report the serendipitous discovery of strong magnetic signals in rhombohedral C60. Our intention was to search for superconductivity in polymerized C60; however, it appears that our high-pressure, high-temperature polymerization process results in a magnetically ordered state. The material exhibits features typical of ferromagnets: saturation magnetization, large hysteresis and attachment to a magnet at room temperature. The temperature dependences of the saturation and remanent magnetization indicate a Curie temperature near 500 K. PMID:11607027

Makarova, T L; Sundqvist, B; Höhne, R; Esquinazi, P; Kopelevich, Y; Scharff, P; Davydov, V A; Kashevarova, L S; Rakhmanina, A V

2001-10-18

283

Electrospinning carbon nanotube polymer composite nanofibers  

Microsoft Academic Search

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

Leslie Y. Yeo; James R. Friend

2006-01-01

284

Single carbon nanotube based infrared sensor  

NASA Astrophysics Data System (ADS)

As a one-dimensional nanostructural material, carbon nanotube (CNT) has been used to build different nanoelectronic devices due to its unique electrical properties. In this paper, the infrared (IR) responses of individual single-wall carbon nanotube (SWNT) and SWNT film are studied. A single-wall carbon nanotube is assembled onto a pair of electrodes to form Schottky contacts. The photongenerated electron-hole pairs within the carbon nanotube are seperated by an external electric field between the two electrodes. The separated carriers contribute to the current flowing through the carbon nanotube and form photocurrent. By monitoring the photocurrent, the incident infrared can be detected and quantitated. The single-wall carbon nanotube based infrared sensor is designed and a series of efficient and reliable fabrication and assembly processes are developed for the sensor fabrication. With an atomic force microscope based nanomanipulation system as the assembly tool, a single carbon nanotube can be easily assembled onto the electrodes. Since the assembly process is controllable and reliable, it becomes possible to fabricate an individual carbon nanotubes based infrared sensor array, which was difficult to fabricate with other fabrication method. The photocurrent responses of individual SWNT IR sensor and SWNT film IR sensor are measured and analyzed. Experimental results show the good sensitivity of SWNTs to the infrared light. Our results shows a three orders higher photocurrent than the previous reported results. It has also been shown that an individual SWNT IR sensor is more sensitive than a SWNT film IR sensor.

Zhang, Jiangbo; Xi, Ning; Chan, Hoyin; Li, Guangyong

2006-10-01

285

Single wall carbon nanotube double quantum dot  

Microsoft Academic Search

The authors report on two top-gate defined, coupled quantum dots in a semiconducting single wall carbon nanotube, constituting a tunable double quantum dot system. The single wall carbon nanotubes are contacted by titanium electrodes and gated by three narrow top-gate electrodes as well as a back gate. The authors show that a bias spectroscopy plot on just one of the

H. I. Jørgensen; K. Grove-Rasmussen; J. R. Hauptmann; P. E. Lindelof

2006-01-01

286

Single Carbon Nanotube Transistor at GHz Frequency  

E-print Network

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

Plaçais, Bernard

287

Multifunctional Catalysts for Singlewall Carbon Nanotube  

E-print Network

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

Guo, Ting

288

Transparent and Flexible Carbon Nanotube Transistors  

E-print Network

Transparent and Flexible Carbon Nanotube Transistors E. Artukovic, M. Kaempgen, D. S. Hecht, S We report the fabrication of transparent and flexible transistors where both the bottom gate and the conducting channel are carbon nanotube networks of different densities and Parylene N is the gate insulator

Gruner, George

289

Longitudinal solitons in carbon nanotubes  

SciTech Connect

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.

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

2001-07-15

290

Ultrasonic absorption in carbon nanotube suspensions  

NASA Astrophysics Data System (ADS)

Experimental results of measuring ultrasonic absorption in suspensions of multiwall carbon nanotubes are presented. The measured values of the absorption coefficient considerably exceed the corresponding values obtained for nearly spherical fine carbon particles.

Mansfel'D, A. D.; Sanin, A. G.; Sanina, O. A.; Kaverin, B. S.; Ob”Edkov, A. M.; Egorov, V. A.

2010-03-01

291

Carbon nanotubes : synthesis, characterization, and applications  

E-print Network

copper, and yttrium have been used as co-catalysts [178, 438], producing yields of single-walled carbon nanotubescopper TEM grid (Electron Microscopy Sciences, part #FF200-Cu) across the sample, transferring a small quantity of carbon nanotubes

Deck, Christian Peter

2009-01-01

292

Making Macroscopic Assemblies of Aligned Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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 of the method (see figure) includes a reservoir containing SWNTs dispersed in a suspending agent (for example, dimethylformamide) and a reservoir containing a suitable solvent (for example, water mixed with a surfactant). By use of either pressurized gas supplied from upstream or suction from downstream, the suspension of SWNTs and the solvent are forced to mix and flow into a tank. A filter inside the tank contains pores small enough to prevent the passage of most SWNTs, but large enough to allow the passage of molecules of the solvent and suspending agent. The filter is oriented perpendicular to the flow path. A magnetic field parallel to the plane of the filter is applied. The success of the method is based on the tendency of SWNTs to become aligned with their longitudinal axes parallel to an applied magnetic field. The alignment energy of an SWNT increases with the length of the SWNT and the magnetic-field strength. In order to obtain an acceptably small degree of statistical deviation of SWNTs of a given length from alignment with a magnetic field, one must make the field strong enough so that the thermal energy associated with rotation of an SWNT away from alignment is less than the alignment energy.

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

293

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

PubMed

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

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

2014-11-15

294

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

PubMed

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 ?mol L(-1) sotalol with a detection limit of 0.09 ?mol 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. PMID:25428063

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

2013-01-01

295

Carbon Nanotube Thin Film Transistors Using Carbon Nanotube Electrodes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) have attracted a significant attention in recent years due to their exceptional electronics, optical and mechanical properties. In particular, CNT thin film transistors (TFTs) are considered as promising active components in the next-generation flexible, transparent, and invisible electronics. Due to lack of transparency and flexibility, metal electrodes are not suitable for CNT TFTs in their transparent and flexible electronic applications. In this talk, we will discuss the high-performance CNT TFTs where densely aligned array of metallic single walled carbon nanotubes (SWNTs) were used as source and drain electrodes while semiconducting enriched aligned SWNTs (s-SWNT) were used as a channel material. The both metallic SWNTs in the electrodes and s-SWNTs in the channel are aligned via dielectrophoresis using a high quality surfactant-free solution. We show that the performance of the s-SWNT devices with metallic SWNT electrodes is significantly improved than that of the devices with Pd electrodes. In order to find the information about injection barrier between s-SWNT and metallic SWNT interface, we carry out low temperature electron transport measurement of our devices. We will discuss the detailed analysis of the low temperature data.

Kang, Narae; Sarker, Biddut K.; Khondaker, Saiful I.

2013-03-01

296

Hydrogenation of single-walled carbon nanotubes  

E-print Network

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

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

2005-10-14

297

Nematic Anchoring on Carbon Nanotubes  

E-print Network

A dilute suspension of carbon nanotubes (CNTs) in a nematic liquid crystal (LC) does not disturb the LC director. Due to a strong LC-CNT anchoring energy and structural symmetry matching, CNT long axis follows the director field, possessing enhanced dielectric anisotropy. This strong anchoring energy stabilizes local pseudo-nematic domains, resulting in non-zero dielectric anisotropy in the isotropic phase. These anisotropic domains respond to external electric fields and show intrinsic frequency response. The presence of these domains makes the isotropic phase field-responsive, giving rise to a large dielectric hysteresis effect.

Rajratan Basu; Germano S. Iannacchione

2009-09-28

298

Carbon nanotube growth density control  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

299

Coated carbon nanotube array electrodes  

DOEpatents

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

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

2008-10-28

300

Coated carbon nanotube array electrodes  

DOEpatents

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

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

2006-12-12

301

Mechanics of carbon nanotube scission under sonication  

NASA Astrophysics Data System (ADS)

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

Stegen, J.

2014-06-01

302

Carbon nanotube materials characterization and devices design  

NASA Astrophysics Data System (ADS)

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.

Li, Weifeng

303

The polarized carbon nanotube thin film LED.  

PubMed

We demonstrate a light emitting p-i-n diode made of a highly aligned film of separated (99%) semiconducting carbon nanotubes, self-assembled from solution. By using a split gate technique, we create p- and n-doped regions in the nanotube film that are separated by a micron-wide gap. We inject p- and n-type charge carriers into the device channel from opposite contacts and investigate the radiative recombination using optical micro-spectroscopy. We find that the threshold-less light generation efficiency in the intrinsic carbon nanotube film segment can be enhanced by increasing the potential drop across the junction, demonstrating the LED-principle in a carbon nanotube film for the first time. The device emits infrared light that is polarized along the long axes of the carbon nanotubes that form the aligned film. PMID:21164919

Kinoshita, Megumi; Steiner, Mathias; Engel, Michael; Small, Joshua P; Green, Alexander A; Hersam, Mark C; Krupke, Ralph; Mendez, Emilio E; Avouris, Phaedon

2010-12-01

304

Review of carbon nanotube nanoelectronics and macroelectronics  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

305

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

PubMed

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

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

2014-12-10

306

Carbon nanotubes for inducing magnetotactic properties into cells  

Microsoft Academic Search

In this paper we present a method to make cells magnetotactic by using carbon nanotubes (CNTs). The key of the method consists of a highly biocompatible dispersion of CNTs. These CNTs, once added to culture medium of neuroblastoma cells, strongly interact with the cell membrane. CNTs-conjugated cells appear to be sensitive to applied magnetic field gradient and move towards the

V. Pensabene; M. Marino; A. Menciassi; P. Dario

2008-01-01

307

THz bandwidth optical switching with carbon nanotube metamaterial  

E-print Network

nanostructure of a plasmonic metamaterial with semiconducting single-walled carbon nanotubes. A modulation depth. Averitt, "Dynamical electric and magnetic metamaterial response at terahertz frequencies," Phys. Rev. Lett.-Y. Wang, X. Zhang, F. Wang, and Y. R. Shen, "Ultrafast modulation of optical metamaterials," Opt. Express

Zheludev, Nikolay

308

Development of Carbon-Nanotube/Polymer Composites  

NASA Technical Reports Server (NTRS)

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.

Reynolds, Thomas A.

2005-01-01

309

Conceptual design of carbon nanotube processes  

Microsoft Academic Search

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

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

2007-01-01

310

Sonochemical production of a carbon nanotube  

Microsoft Academic Search

Sonochemical production of a carbon nanotube has been studied. The carbon nanotube is produced by applying ultrasound to liquid chlorobenzene with ZnCl2 particles and to o-dichlorobenzene with ZnCl2 and Zn particles. It is considered that the polymer and the disordered carbon, which are formed by cavitational collapse in homogeneous liquid, are annealed by the inter-particle collision induced by the turbulent

R. Katoh; Y. Tasaka; E. Sekreta; M. Yumura; F. Ikazaki; Y. Kakudate; S. Fujiwara

1999-01-01

311

All Carbon Nanotubes Are Not Created Equal  

Microsoft Academic Search

\\u000a This chapter presents the various factors that enter into consideration when choosing the source of carbon nanotubes for a\\u000a specific application. Carbon nanotubes are giant molecules made of pure carbon. They have captured the imagination of the\\u000a scientific community by the unique structure that provides superior physical, chemical, and electrical properties. However,\\u000a a surprisingly wide disparity exists between the intrinsic

Gyula Eres; D. B. Geohegan; A. A. Puretzky; C. M. Rouleau

2010-01-01

312

Ballistic carbon nanotube field-effect transistors  

Microsoft Academic Search

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

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

2003-01-01

313

Pyrolytic carbon nanotubes from vapor-grown carbon fibers  

Microsoft Academic Search

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

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

1995-01-01

314

Carbon nanotube fiber spun from wetted ribbon  

DOEpatents

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

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

2014-04-29

315

Carbon Nanotubes for Human Space Flight  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

316

Excimer laser treatment of carbon nanotubes  

Microsoft Academic Search

In this work we examine laser treatment of unaligned bulk nanotube samples as a potentially simple and fast purification method. The effects of laser treatment by a 248 nm excimer laser at various pulse lengths and time of exposure are evaluated to gain control and selectivity for the removal of carbon impurities from nanotube samples.

K. E. H. Gilbert; D. A. Keenan; A. C. Dillon; T. Gennett; P. Rice; J. H. Lehman

2006-01-01

317

New Nanopumping Effects with Carbon Nanotubes  

Microsoft Academic Search

ABSTRACT Molecular dynamics (MD) simulations show macroscopic flows of atomic and molecular hydrogen, helium, and a mixture of both gases both inside and outside a carbon nanotube. In particular, the simulations show a “nanoseparation” effect of the two gases. In a previous paper we showed that propagation of Rayleigh traveling waves on the nanotube surface activates a macroscopic flow of

Z. Insepov

318

Carbon nanotube diode performance and photovoltaic response  

Microsoft Academic Search

Due to their unique electronic properties, carbon nanotubes have been at the forefront in the development of next generation electronic devices. The p-n diode is arguably the most pivotal electronic and photovoltaic device. Up to now, nanotube diodes have had major drawbacks including complex quad-terminal device geometries to achieve electrostatic doping, large series resistances from the inclusion of an intrinsic

Daner Abdula; Moonsub Shim

2009-01-01

319

Carbon nanotubes and their recent developments  

Microsoft Academic Search

In his book published in 1985 Drexler proposed a molecular bearing consisting of two graphitic nanotubes of different diameter which are concentrically arranged (1992). It was a virtual operation inside a computer. This dream, however, has become more realistic by the discovery of carbon nanotubes by the author (1991). The discovery, unique atomic structures, production, growth, expected properties and some

S. Iijima

1998-01-01

320

Processing carbon nanotubes with holographic optical tweezers  

E-print Network

, and perhaps even individual nanotubes, can be transported at high speeds, deposited onto substrates, untangled processing with light. © 2012 Optical Society of America OCIS codes: (140.7010) Trapping; (090.1760) Computer of aligned carbon nanotubes via laser trimming,'' Nanotechnology 14, 433--437 (2003). 16. L. A. Nagahara, I

Grier, David

321

Processing carbon nanotubes with holographic optical tweezers  

E-print Network

nanotubes, can be transported at high speeds, deposited onto substrates, untangled, and selectively ablated. © 2012 Optical Society of America OCIS codes: (140.7010) Trapping; (090.1760) Computer holography; (120, "Large area patterned arrays of aligned carbon nanotubes via laser trimming," Nanotechnology 14, 433

Grier, David

322

Electron localization in superlattice-carbon nanotubes  

NASA Astrophysics Data System (ADS)

Electronic transport properties of superlattice-carbon nanotubes (SCNTs) attached to semi-infinite clean metallic carbon nanotube (CNT) leads are investigated in the framework of a simple model based on mode (momentum)-space within the tight-binding approximation. This model reduces the numerical calculation time and enables us to use the transfer matrix method to investigate transport in an SCNT. We calculate the localization length and density of states (DOS) for various strengths of boron defect. Our numerical results indicate that the localization length decreases with increasing boron concentration, showing the tendency of the system towards the insulating behavior. Also, we observe a nearly stepwise dependence of the localization length on energy at small boron concentration. By controlling the layered boron concentration, the system can be tuned to yield either localized or extended states. These calculations can be generalized to the magnetic defects embedded in the device, which can act as a spin-filter. Our results can serve as a base for developments in designing nano-electronic devices.

Shokri, A. A.; Khoeini, F.

2010-11-01

323

Testing and characterization of carbon nanotubes as strain sensors  

E-print Network

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

Diaz, Juan D

2011-01-01

324

Spin transport across carbon nanotube quantum dots  

NASA Astrophysics Data System (ADS)

We investigate linear and nonlinear transport in interacting single-wall carbon nanotubes (SWCNTs) that are weakly attached to ferromagnetic leads. For the reduced density matrix of a SWCNT quantum dot, equations of motion which account for an arbitrarily vectored magnetization of the contacts are derived. We focus on the case of large diameter nanotubes where exchange effects emerging from short-ranged processes can be excluded and the four-electron periodicity at low bias can be observed. This yields in principle four distinct resonant tunnelling regimes, but due to symmetries in the involved groundstates, each two possess a mirror-symmetry. With a non-collinear configuration, we recover at the 4\\mathbb{N}\\leftrightarrow4\\mathbb{N}\\pm1 resonances the analytical results known for the angular dependence of the conductance of a single level quantum dot or a metallic island. The two other cases are treated numerically and show on the first glance similar, yet not analytically describable dependences. In the nonlinear regime, negative differential conductance features occur for non-collinear lead magnetizations.

Koller, Sonja; Mayrhofer, Leonhard; Grifoni, Milena

2007-09-01

325

Carbon nanofibers and carbon nanotubes in regenerative medicine  

Microsoft Academic Search

Carbon nanotubes and carbon nanofibers have long been investigated for applications in composite structural materials, semiconductor devices, and sensors. With the recent well-documented ability to chemically modify nanofibrous carbon materials to improve their solubility and biocompatibility properties: a whole new class of bioactive carbon nanostructures has been created for biological applications. This review focuses on the latest applications of carbon

Phong A. Tran; Lijie Zhang; Thomas J. Webster

2009-01-01

326

Infrared transparent carbon nanotube thin films  

NASA Astrophysics Data System (ADS)

We have measured the infrared properties of optically transparent and electrically conductive single walled carbon nanotube thin films. We found that nanotube films with sheet resistance values of 200 ?/sq show outstanding transmittance in the infrared range up to at least 22 ?m, with an average transmittance greater than 90% over this range. The infrared properties of various materials were compared and we found that transparent nanotube electrodes and transparent graphene electrodes outperform the others in several key categories. This study opens another important application area for conductive nanotube thin films.

Hu, Liangbing; Hecht, David S.; Grüner, George

2009-02-01

327

Microfabricated electroactive carbon nanotube actuators  

NASA Astrophysics Data System (ADS)

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 .

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

2001-07-01

328

Carbon nanotube synthesis for integrated circuit interconnects  

E-print Network

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

Nessim, Gilbert Daniel

2009-01-01

329

Carbon nanotube bearings in theory and practice  

E-print Network

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

Cook, Eugene Hightower

2011-01-01

330

Transplanting assembly of individual carbon nanotubes  

E-print Network

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

Kim, Soohyung

2009-01-01

331

Carbon nanotube polymer composition and devices  

DOEpatents

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

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

2011-06-14

332

Carbon nanotube interconnects for IC chips  

E-print Network

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

Anwar Ali, Hashina Parveen

2006-01-01

333

Chemistry in the nanospace of carbon nanotubes.  

PubMed

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

Wang, Zhiyong; Shi, Zujin; Gu, Zhennan

2010-05-01

334

Functionalization and applications of carbon nanotubes  

E-print Network

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

Schnorr, Jan M. (Jan Markus)

2012-01-01

335

Continuous Growth of Vertically Aligned Carbon Nanotubes  

E-print Network

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

Guzman de Villoria, R.

336

Carbon nanotube heat-exchange systems  

DOEpatents

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

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

2008-11-11

337

Towards a carbon nanotube antibody sensor  

E-print Network

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

Bojö, Peter

2012-01-01

338

Carbon nanotube-based field ionization vacuum  

E-print Network

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

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

2012-01-01

339

Carbon nanotube metrology in a CD SEM  

NASA Astrophysics Data System (ADS)

In the Nantero NRAM process, a carbon nanotube film is patterned using conventional photolithography and etch techniques. CD SEM metrology of the printed resist image is straightforward. However, challenges arise when SEM inspecting an etched nanotube pattern. Under conventional SEM inspection, a nanotube pattern is nearly invisible. In order to facilitate nanotube pattern characterization, metrology structures have been developed which use passive voltage contrast to cause electron emission from the nanotube pattern and associated conducting structures. These enable manual inspection of the nanotubes, along with automated pattern recognition and automated CD measurement. The voltage contrast is achieved by connecting the nanotubes to a remote "charge-sink" outside the image field consisting of a large rectangle of metal. The voltage contrast occurs with no extra electrical connection to the wafer, and without special SEM components or beam adjustment. The metrology structures are used in two general ways: 1. Nanotubes are clearly imaged, enabling inspection, CD measurement, coat-quality characterization, etc. 2. Indicator structures in associated process layers light up when contacted by nanotubes, enabling measurements of line-end shortening; etch bias; overlay; etc. Various structures have been developed: 1. CD cells for manual and automated CD measurement. 2. Vernier structures for characterization of overlay, line-end shortening and etch-bias. 3. Serpentine structures for characterization of nanotube coat quality using conduction length.

Yates, Colin; Rueckes, Thomas; Carter, Richard J.

2007-03-01

340

Controlled Deposition and Alignment of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

A carbon nanotube (CNT) attraction material is deposited on a substrate in the gap region between two electrodes on the . substrate. An electric potential is applied to the two electrodes. The CNT attraction material is wetted with a solution defined by a 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.

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

2009-01-01

341

Mechanical and thermal properties of carbon nanotubes  

Microsoft Academic Search

This chapter discusses some aspects of the mechanical and thermal properties of carbon nano-tubes. The tensile and bending stiffness constants of ideal multi-walled and single-walled carbon nano-tubes are derived in terms of the known elastic properties of graphite. Tensile strengths are estimated by scaling the 20 GPa tensile strength of Bacon's graphite whiskers. The natural resonance (fundamental vibrational frequency) of

Rodney S. Ruoff; Donald C. Lorents

1995-01-01

342

Controlled Deposition and Alignment of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

343

Carbon nanotube temperature and pressure sensors  

DOEpatents

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

Ivanov, Ilia N; Geohegan, David Bruce

2013-10-29

344

Carbon Nanotube Based Light Sensor  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

345

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

NASA Technical Reports Server (NTRS)

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

Yamada, Toshishige

1999-01-01

346

Macroscopic Fibers and Ribbons of Oriented Carbon Nanotubes  

Microsoft Academic Search

A simple method was used to assemble single-walled carbon nanotubes into indefinitely long ribbons and fibers. The processing consists of dispersing the nanotubes in surfactant solutions, recondensing the nanotubes in the flow of a polymer solution to form a nanotube mesh, and then collating this mesh to a nanotube fiber. Flow-induced alignment may lead to a preferential orientation of the

Brigitte Vigolo; Alain Pénicaud; Claude Coulon; Cédric Sauder; René Pailler; Catherine Journet; Patrick Bernier; Philippe Poulin

2000-01-01

347

Fundamental optical processes in armchair carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

348

Filling of carbon nanotubes and nanofibres  

PubMed Central

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.

Gately, Reece D

2015-01-01

349

Carbon nanotubes for biomedical imaging: the recent advances.  

PubMed

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

Gong, Hua; Peng, Rui; Liu, Zhuang

2013-12-01

350

Method for manufacturing high quality carbon nanotubes  

NASA Technical Reports Server (NTRS)

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.

Benavides, Jeanette M. (Inventor)

2006-01-01

351

Amorphous molecular junctions produced by ion irradiation on carbon nanotubes  

NASA Astrophysics Data System (ADS)

Experiments and molecular dynamics have demonstrated that electron irradiation could create molecular junctions between crossed single-wall carbon nanotubes. Recently molecular dynamics computation predicted that ion irradiation could also join single-walled carbon nanotubes. Employing carbon ion irradiation on multi-walled carbon nanotubes, we find that these nanotubes evolve into amorphous carbon nanowires, more importantly, during the process of which various molecular junctions of amorphous nanowires are formed by welding from crossed carbon nanotubes. It demonstrates that ion-beam irradiation could be an effective way not only for the welding of nanotubes but also for the formation of nanowire junctions.

Wang, Zhenxia; Yu, Liping; Zhang, Wei; Ding, Yinfeng; Li, Yulan; Han, Jiaguang; Zhu, Zhiyuan; Xu, Hongjie; He, Guowei; Chen, Yi; Hu, Gang

2004-04-01

352

Doped Carbon Nanotubes: Synthesis, Characterization and Applications  

Microsoft Academic Search

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

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

353

Interfacial heat flow in carbon nanotube suspensions.  

PubMed

The enormous amount of basic research into carbon nanotubes has sparked interest in the potential applications of these novel materials. One promising use of carbon nanotubes is as fillers in a composite material to improve mechanical behaviour, electrical transport and thermal transport. For composite materials with high thermal conductivity, the thermal conductance across the nanotube-matrix interface is of particular interest. Here we use picosecond transient absorption to measure the interface thermal conductance (G) of carbon nanotubes suspended in surfactant micelles in water. Classical molecular dynamics simulations of heat transfer from a carbon nanotube to a model hydrocarbon liquid are in agreement with experiment. Our findings indicate that heat transport in a nanotube composite material will be limited by the exceptionally small interface thermal conductance (G approximately 12 MW m(-2) K(-1)) and that the thermal conductivity of the composite will be much lower than the value estimated from the intrinsic thermal conductivity of the nanotubes and their volume fraction. PMID:14556001

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

2003-11-01

354

Method for nano-pumping using carbon nanotubes  

DOEpatents

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

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

2009-12-15

355

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

356

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

PubMed

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

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

2014-07-01

357

Carbon nanotubes: synthesis and functionalization   

E-print Network

of single–walled nanotubes (SWNTs) has been studied in two ways. Firstly, a novel iron nanoparticle catalyst for the production of single–walled nanotubes was developed. CVD conditions were established that produced high quality tubes. These optimised CVD...

Andrews, Robert

2007-01-01

358

The 2008 Kavli Prize in Nanoscience: Carbon Nanotubes  

E-print Network

The 2008 Kavli Prize in Nanoscience: Carbon Nanotubes Ali Javey* Department of Electrical-dimensional (1-D) nanomaterials, such as carbon nanotubes and nanowires (NWs), with molecular-scale diameters, a small subset of which are summarized in this article. Carbon Nanotubes. Carbon exhibits remark- able

Javey, Ali

359

MOLECULAR DYNAMICS SIMULATIONS OF HEAT TRANSFER OF CARBON NANOTUBES  

E-print Network

MOLECULAR DYNAMICS SIMULATIONS OF HEAT TRANSFER OF CARBON NANOTUBES J. Shiomi, Y. Igarashi, Y-ku, Tokyo 113-8656, JAPAN Several heat transfer problems related to single-walled carbon nanotubes (SWNTs] is employed as the potential function between carbon and carbon within a nanotube. MD simulations of thermal

Maruyama, Shigeo

360

Scanning tunneling spectroscopy of suspended single-wall carbon nanotubes  

E-print Network

Scanning tunneling spectroscopy of suspended single-wall carbon nanotubes B. J. LeRoy,a) S. G-wall carbon nanotubes that are freely suspended over a trench. The nanotubes were grown by chemical vapor on the freestanding portions of the nanotubes. Spatially resolved spectroscopy on the suspended portion of both

Dekker, Cees

361

Hydrogen Raman shifts in carbon nanotubes from molecular dynamics simulation  

E-print Network

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

Brenner, Donald W.

362

Fabrication of nylon-6/carbon nanotube composites  

NASA Astrophysics Data System (ADS)

A new technique to fabricate nylon-6/carbon nanotube (PA6/CNT) composites is presented. The method involves a pretreatment of carbon nanotubes synthesized by catalytic pyrolysis of hydrocarbon and an improved in-situ process for mixing nanotubes with the nylon 6 matrix. A good bond between carbon nanotubes and the nylon-6 matrix is obtained. Mechanical property measurements indicate that the tensile strength of PA6/CNT composites is improved significantly while the toughness and elongation are somewhat compromised. Scanning electron microscopy (SEM) analysis of the fractured tensile specimens reveals cracking initiated at the wrapping of the CNTs PA6 layer/PA6 matrix interface rather than at the PA6/CNT interface.

Xu, C.; Jia, Z.; Wu, D.; Han, Q.; Meek, T.

2006-05-01

363

Polymerization initated at sidewalls of carbon nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

364

Carbon linear chains inside multiwalled nanotubes  

NASA Astrophysics Data System (ADS)

Multiwalled carbon nanotubes have been deposited on graphite cathodes by using an arc discharge technique in He atmosphere, with the insertion of a catalytic Ni-Cr mixture as well as without catalysers. The topography of such deposition has been investigated by SEM, while a parallel micro-Raman study has revealed, in particular regions of the deposited cathodes, strong bands in the range 1780-1860 cm -1, assignable to linear carbon chains inside the nanotubes. The variation of intensity, frequency and bandwidth of such bands has been investigated, in relation with the spectral characters of the host multiwalled carbon nanotube. In the cathode deposited without catalyst a quite ordered configuration of multiwalled carbon nanotubes is obtained in the central zone, while the maximum concentration of linear carbon chains is found in a ring shaped zone just inside the border. In sample obtained with catalyst the deposited multiwalled carbon nanotubes appear always more disordered, and a remarkable concentration of carbon chains appears in some zones, with a more casual distribution.

Cazzanelli, E.; Caputi, L.; Castriota, M.; Cupolillo, A.; Giallombardo, C.; Papagno, L.

2007-09-01

365

Electronic structure of atomically resolved carbon nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes can be considered as single graphene sheets wrapped up into cylinders. Theoretical studies have shown that nanotubes can be either metallic or semiconducting, depending on minor differences in wrapping angle and diameter. We have obtained scanning tunneling microscopy and spectroscopy results on individual nanotubes which verify this prediction( J.W.G.Wildöer, L.C. Venema, A.G. Rinzler, R.E. Smalley, and C. Dekker, Nature, aimed for publication in Januari 1998). The combination of spectroscopy measurements and atomically resolved images allow to relate the electronic spectra to the wrapping angle and diameter. Tubes with various wrapping angles appear to be either metallic or semiconducting. Carbon nanotubes are expected to be one-dimensional conductors. Sharp peaks in the tunneling density of states that can be associated with the onsets of one-dimensional subbands are indeed observed. Furthermore, we are able to control the length of carbon nanotubes by STM nanostructuring( L.C. Venema, J.W.G. Wildöer, H.J. Temminck Tuinstra, A.G. Rinzler, R.E. Smalley and C. Dekker, Appl. Phys. Lett. (1997)). By applying voltage pulses to the STM tip above a nanotube, the tube can cut into a shorter section. In this way the electronic properties of nanotubes of various lengths can be investigated. footnotetext[0] email: venema@qt.tn.tudelft.nl Work done in collaboration with J.W.G. Wildöer, A.G. Rinzler, R.E. Smalley and C. Dekker.

Venema, Liesbeth

1998-03-01

366

Carbon Nanotube and Graphene Nanoelectromechanical Systems  

NASA Astrophysics Data System (ADS)

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

Aleman, Benjamin Jose

367

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

E-print Network

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

Meyers, Marc A.

368

Carbon nanotube biocompatibility with cardiac muscle cells  

NASA Astrophysics Data System (ADS)

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<0.05). However, overtime cells from a trypsinized nanotube-treated sample continued to grow, and partially recovered the original shape. In conclusion our results demonstrate that highly purified carbon nanotubes possess no evident short-term toxicity and can be considered biocompatible with cardiomyocytes in culture, while the long-term negative effects, that are evidenced after reseeding, are probably due to physical rather than chemical interactions.

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

2006-01-01

369

Analyzing manufacturing methods of carbon nanotubes for commercialization  

E-print Network

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

Dee, H. Devin (Herbert Devin)

2013-01-01

370

Methods for Gas Sensing with Single-Walled Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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.

Kaul, Anupama B. (Inventor)

2013-01-01

371

Synthesis and fluid interaction of ultra long carbon nanotubes  

E-print Network

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

Hofmann, Mario

2009-01-01

372

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 ...

373

Carbon Nanotube-Based Synthetic Gecko Tapes  

NASA Astrophysics Data System (ADS)

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.

Dhinojwala, Ali

2008-03-01

374

Selective Functionalization of Carbon Nanotubes: Part II  

NASA Technical Reports Server (NTRS)

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

Meyyappan, Meyya; Khare, Bishun

2010-01-01

375

NMR Investigation of the local diamagnetic properties of carbon structures with multilayer nanotubes  

NASA Astrophysics Data System (ADS)

The reasons for the high diamagnetic susceptibility of carbon columns, which are covered with a nanotube mesh, from the interior part of cathode deposits have been studied by means of NMR. A comparative study is made of the C13 NMR spectra and the magnetic susceptibility of carbon columns before and after ultrasonic processing as well as of finely dispersed material, obtained as a result of such processing, enriched with multilayer nanotubes. The strong diamagnetism of the carbon columns is apparently associated with a quite dense conglomerate of graphite particles, nanotubes, and multilayer polyhedral particles present in their core and not with the surface mesh of multilayer nanotubes. To make a more accurate determination of the character of the anisotropy of the magnetic susceptibility of multilayer carbon nanotubes, the form of the C13 NMR spectra of samples enriched with multilayer nanotubes, where the nanotubes are either not oriented or only partially oriented, is analyzed. It is shown that the diamagnetic susceptibility of multilayer carbon nanotubes is highest when the magnetic field is oriented perpendicular to their axis.

Nikolaev, E. G.; Omel'Yanovski?, O. E.; Prudkovski?, V. S.; Sadakov, A. V.; Tsebro, V. I.

2009-02-01

376

Carbon Nanotubes and Chronic Granulomatous Disease  

PubMed Central

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

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

2014-01-01

377

Carbon Nanotube Tower-Based Supercapacitor  

NASA Technical Reports Server (NTRS)

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

Meyyappan, Meyya (Inventor)

2012-01-01

378

Biocompatibility of immobilized aligned carbon nanotubes.  

PubMed

In vivo host responses to an electrode-like array of aligned carbon nanotubes (ACNTs) embedded within a biopolymer sheet are reported. This biocompatibility study assesses the suitability of immobilized carbon nanotubes for bionic devices. Inflammatory responses and foreign-body histiocytic reactions are not substantially elevated when compared to negative controls following 12 weeks implantation. A fibrous capsule isolates the implanted ACNTs from the surrounding muscle tissue. Filamentous nanotube fragments are engulfed by macrophages, and globular debris is incorporated into the fibrous capsule with no further reaction. Scattered leukocytes are observed, adherent to the ACNT surface. These data indicate that there is a minimal local foreign-body response to immobilized ACNTs, that detached fragments are phagocytosed into an inert material, and that ACNTs do not attract high levels of surface fouling. Collectively, these results suggest that immobilized nanotube structures should be considered for further investigation as bionic components. PMID:21374804

Nayagam, David A X; Williams, Richard A; Chen, Jun; Magee, Kylie A; Irwin, Jennifer; Tan, Justin; Innis, Peter; Leung, Ronald T; Finch, Sue; Williams, Chris E; Clark, Graeme M; Wallace, Gordon G

2011-04-18

379

Evaluating the characteristics of multiwall carbon nanotubes  

Microsoft Academic Search

During the past 20years, multiwall carbon nanotubes (MWCNTs) have become an important industrial material. Hundreds of tons are produced each year. This review is a survey of the scientific literature, motivated by industrial requirements and guidelines for environment, health and safety compliance. Sampling, size, area, density, color, crystallinity, as well as purity compared to properties of non-MWCNT carbon and catalyst

John H. Lehman; Mauricio Terrones; Elisabeth Mansfield; Katherine E. Hurst; Vincent Meunier

2011-01-01

380

Narrow graphene nanoribbons from carbon nanotubes  

Microsoft Academic Search

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

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

2009-01-01

381

Raman spectroscopy of single wall carbon nanotubes  

E-print Network

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

Son, HyungBin, 1981-

2008-01-01

382

Carbon nanotube composites for thermal management  

Microsoft Academic Search

Single-wall carbon nanotubes (SWNTs) were used to augment the thermal transport properties of industrial epoxy. Samples loaded with 1 wt % unpurified SWNT material showed a 70% increase in thermal conductivity at 40 K, rising to 125% at room temperature; the enhancement due to 1 wt % loading of vapor grown carbon fibers was three times smaller. Electrical conductivity data

M. J. Biercuk; M. C. Llaguno; M. Radosavljevic; J. K. Hyun; A. T. Johnson; J. E. Fischer

2002-01-01

383

Carbon nanotube photovoltaic device with asymmetrical contacts  

Microsoft Academic Search

A photovoltaic (PV) device based on ``high-work-function metal\\/single-walled carbon nanotube\\/low-work-function metal'' hybrid junction has been studied theoretically by the self-consistent nonequilibrium Green's function approach. The PV effect and power conversion efficiency (?) of the device under light illumination are simulated, with a monochromatic ? of higher than 40% for incident photon energies near the nanotube band-gap energy predicted. It is

Changxin Chen; Wei Zhang; Eric Siu-Wai Kong; Yafei Zhang

2009-01-01

384

Elastic Properties of Carbon Nanotubes and Nanoropes  

Microsoft Academic Search

Elastic properties of carbon nanotubes and nanoropes are investigated using\\u000aan empirical force-constant model. For single and multi-wall nanotubes the\\u000aelastic moduli are shown to be insensitive to details of the structure such as\\u000athe helicity, the tube radius and the number of layers. The tensile Young's\\u000amodulus and the torsion shear modulus calculated are comparable to that of the

Jian Ping Lu

1997-01-01

385

Biomedical Applications of Functionalised Carbon Nanotubes  

Microsoft Academic Search

\\u000a This chapter describes the developing potential of carbon nanotubes (CNTs) in biomedicine. Methodologies to render nanotubes\\u000a biocompatible, the related studies on cell uptake, applications in vaccine delivery, interaction with nucleic acids and impact\\u000a on health will be described. The use of CNTs for biomedical applications is acquiring more and more substantiating evidence\\u000a for efficient development. It is clear that some

Alberto Bianco; Raquel Sainz; Shouping Li; Hélène Dumortier; Lara Lacerda; Kostas Kostarelos; Silvia Giordani; Maurizio Prato

2008-01-01

386

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

PubMed Central

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

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

2013-01-01

387

Fabrication and characterization of polycarbonate\\/carbon nanotubes composites  

Microsoft Academic Search

Polycarbonate composites containing carbon nanotubes can be prepared through a method combined solution mixing and precipitation together. The surface chemical state of the purified carbon nanotubes was studied through X-ray photoelectron spectroscopy, and the state of carbon nanotubes in the composites through transmission electron microscopy and scanning electron microscopy. Results showed that some polar functional groups such as CO, CO

Li Chen; Xiu-Jiang Pang; Mei-Zhen Qu; Qing-tang Zhang; Bin Wang; Bai-Lan Zhang; Zuo-Long Yu

2006-01-01

388

Carbon nanotube (CNT) filled adhesives for microelectronic packaging  

Microsoft Academic Search

This project evaluated the use of carbon nanotubes as a filler in electrically conducting adhesives in order to enhance the electrical, mechanical and thermal performance. As the carbon nanotubes caused a marked increase in the viscosity of the adhesive, a low viscosity polymer matrix (< 100 mPas) was chosen. This allowed a high CNT content. Multi-wall carbon nanotubes (MWNTs) were

M. Wirts-Rutters; Matthias Heimann; Jana Kolbe; Klaus-Juergen Wolter

2008-01-01

389

Structures of ultrathin copper nanowires encapsulated in carbon nanotubes  

Microsoft Academic Search

We have investigated the structures of copper nanowires encapsulated in carbon nanotubes using a structural optimization process applied to the steepest descent method. The results showed that the stable morphology of the cylindrical ultrathin copper nanowires in carbon nanotubes is multishell packs consisting of coaxial cylindrical shells. As the diameter of carbon nanotubes increased, the encapsulated copper nanowires have the

Won Young Choi; Jeong Won Kang; Ho Jung Hwang

2003-01-01

390

Performance Analysis of Carbon Nanotube Interconnects for VLSI Applications  

E-print Network

, for example the transition from aluminum to copper some years back. Carbon nanotubes have recently beenPerformance Analysis of Carbon Nanotube Interconnects for VLSI Applications Navin Srivastava the applicability of carbon nanotube (CNT) bundles as interconnects for VLSI circuits, while taking into account

391

Broadband Photodetector Based on Carbon Nanotube Fibers Simon Lee,1  

E-print Network

of applications of carbon nanotubes has been constantly expanding since its inception. From being a copper wire UG-30 Broadband Photodetector Based on Carbon Nanotube Fibers Simon Lee,1 Xuan Wang substitute to being a space elevator to the moon, carbon nanotubes have been in the spotlight for several

392

ORIGINAL PAPER Conceptual design of carbon nanotube processes  

E-print Network

conductivity similar to copper. The biggest challenge in developing potential applications for carbon nanotubesORIGINAL PAPER Conceptual design of carbon nanotube processes Adedeji E. Agboola Ã? Ralph W. Pike Ã? online: 10 January 2007 Ã? Springer-Verlag 2007 Abstract Carbon nanotubes, discovered in 1991, are a new

Pike, Ralph W.

393

Simulation of the Band Structure of Graphene and Carbon Nanotube  

Microsoft Academic Search

Simulation technique has been performed to simulate the band structure of both graphene and carbon nanotube. Accordingly, the dispersion relations for graphene and carbon nanotube are deduced analytically, using the tight binding model & LCAO scheme. The results from the simulation of the dispersion relation of both graphene and carbon nanotube were found to be consistent with those in the

Aziz N Mina; Attia A Awadallah; Adel H Phillips; Riham R Ahmed

2012-01-01

394

Nanoelectro-mechanical systems based on carbon nanotubes  

E-print Network

:" , : Nanoelectro-mechanical systems based on carbon nanotubes ,81.90.88,81:39 ( -) 81:99 , ' ", '" #12;"Atomistic simulations of vibration of carbon nanotubes: is it possible to measure the mass of single atom?" Polina Pine Supervisor: Joan Adler, Yuval E. Yaish Carbon nanotubes

Adler, Joan

395

Repeat Space Theory Applied to Carbon Nanotubes and  

E-print Network

1 Repeat Space Theory Applied to Carbon Nanotubes and Matrix Art Shigeru Arimoto* , Massoud Amini with the series of papers entitled "Repeat space theory applied to carbon nanotubes and related molecular networks formulated and discussed. The Matrix Art pictures of carbon nanotube energy band curves played a significant

Taylor, Keith F.

396

Carbon nanotubes used to form fast, flexible circuitry  

E-print Network

Carbon nanotubes used to form fast, flexible circuitry By Yun Xie | Published: July 23, 2008 - 12 the semiconductor portion of these flexible integrated circuits. Related Stories Carbon nanotubes as molecular scales Carbon nanotubes send electrons for a spin These conventional materials are serviceable

Rogers, John A.

397

Passive Ammonia Sensor: RFID Tag Integrating Carbon Nanotubes  

E-print Network

Passive Ammonia Sensor: RFID Tag Integrating Carbon Nanotubes C. Occhiuzzi (1), A.Rida(2), G@disp.uniroma2.it (4)emmanouil.tentzeris@ece.gatech.edu Abstract--In this paper Single-Wall Carbon Nanotubes (CNT require micro- fabrication techniques, power supply and specific electronics. Carbon Nanotubes (CNT

Tentzeris, Manos

398

Carbon Nanotubes Encapsulating Superconducting Single-Crystalline Tin  

E-print Network

Carbon Nanotubes Encapsulating Superconducting Single-Crystalline Tin Nanowires Lubos Jankovic carbon nanotubes encapsulating single crystalline superconducting tin nanowires by employing is monochromatic6 and that e-beams emitted from different sites of a carbon nanotube can interfere with each other

Trikalitis, Pantelis N.

399

Coherent Lattice Vibrations in Single-Walled Carbon Nanotubes  

E-print Network

Coherent Lattice Vibrations in Single-Walled Carbon Nanotubes Yong-Sik Lim,, Ki-Ju Yee,§ Ji-Hee Kim-walled carbon nanotubes corresponding to the radial breathing mode (RBM) using ultrashort laser pulses. Because electronic and vibrational dynamics in real time.2,3 Single- walled carbon nanotubes (SWNTs

Kono, Junichiro

400

Low dimensional heat and mass transport in carbon nanotubes  

E-print Network

Low dimensional heat and mass transport in carbon nanotubes Junichiro Shiomi, Shigeo Maruyama 1 Keywords: Single-walled carbon nanotube, Thermal transport, Mass transport, Interface Single-walled carbon nanotubes (SWNTs) have caught much attention as materials realizing various low-dimensional transport

Maruyama, Shigeo

401

Single-Walle 4. Single-Walled Carbon Nanotubes  

E-print Network

105 Single-Walle 4. Single-Walled Carbon Nanotubes Sebastien Nanot, Nicholas A. Thompson, Ji Single-walled carbon nanotubes (SWCNTs) are hol- low, long cylinders with extremely large aspect ratios their discovery, carbon nanotubes continue to surprise researchers with potential new applications and interesting

Kono, Junichiro

402

Molecular mechanics modeling for properties of carbon nanotubes  

Microsoft Academic Search

Molecular mechanics calculations for in-plane stiffness, shear modulus, and the bending rigidity of single-walled carbon nanotubes are reported in this work through the calculations of the strain energy for carbon nanotubes and graphite sheets subjected to various types of loading. Elastic rod and plate theories are employed to link the material properties of carbon nanotubes directly to the molecular mechanics

Q. Wang; K. M. Liew

2008-01-01

403

Novel 8-Phase VCO Design using Carbon Nanotube Transistor (CNT)  

E-print Network

Novel 8-Phase VCO Design using Carbon Nanotube Transistor (CNT) Rui Tang Oracle Corporation 4180-phase VCO design implemented using Carbon Nanotube Field-Effect Transistors (CNTFETs). Carbon Nanotube VCO architecture to generate 8-phase clock signal. In this paper, the VCO design from [9] is ported

Ayers, Joseph

404

Mechanics of Carbon Nanotubes and their Polymer Composites  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

405

Bulk Cutting of Carbon Nanotubes Using Electron Beam Irradiation  

NASA Technical Reports Server (NTRS)

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.

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

406

Conductive silver thick films filled with carbon nanotubes  

Microsoft Academic Search

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

Marcin Sloma; Malgorzata Jakubowska; Anna Mlozniak; Ryszard Jezior

407

Measurement Challenges for Carbon Nanotube Material  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

408

Thermal Transport in Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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

Christman, Jeremy; Moore, Andrew; Khatun, Mahfuza

2011-10-01

409

Elastomer Reinforced with Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

Hudson, Jared L.; Krishnamoorti, Ramanan

2009-01-01

410

Does water dope carbon nanotubes?  

SciTech Connect

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.

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

2014-10-28

411

Second-order harmonic and combination modes in graphite, single wall carbon nanotube bundles, and isolated single wall carbon nanotubes  

E-print Network

pyrolytic graphite (HOPG), in single wall carbon nanotube (SWNT) bundles, and in isolated SWNTs. We foundSecond-order harmonic and combination modes in graphite, single wall carbon nanotube bundles, and isolated single wall carbon nanotubes V. W. Brara , Ge. G. Samsonidzeb , M. S. Dresselhausa,b , G

412

Propagative Landau states and Fermi level pinning in carbon nanotubes.  

PubMed

We present strong evidence of Landau states formation in multiwalled carbon nanotubes with metallic or semiconducting outer shells, under magnetic fields as high as 60 T. Magnetoconductance data are found to converge to a gate-independent value for semiconducting shells, whereas for metallic shells, the Landau states introduce a strong reintroduction of backscattering and Fermi level pinning close to the charge neutrality point. Electronic band structure and transport calculations provide a consistent interpretation of the experimental data. PMID:20366272

Nanot, Sébastien; Avriller, Rémi; Escoffier, Walter; Broto, Jean-Marc; Roche, Stephan; Raquet, Bertrand

2009-12-18

413

Carbon nanotube-chalcogenide glass composite  

SciTech Connect

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

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

2010-01-15

414

Modelling Carbon Nanotubes-Based Mediatorless Biosensor  

PubMed Central

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

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

2012-01-01

415

Carbon nanotube suspensions, dispersions, & composites  

NASA Astrophysics Data System (ADS)

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

Simmons, Trevor John

416

Building smart materials based on carbon nanotubes  

NASA Astrophysics Data System (ADS)

The paper discusses the development of polymer composite materials based on carbon nanotubes. Carbon Nanotubes can be used to form polymer hybrid materials that have good elastic properties, piezoresistive sensing, and electrochemical actuation. Of particular interest are smart nanocomposite materials that are strong and self-sensing for structural health monitoring, or self-actuating to improve the performance and efficiency of structures and devices. Since nanoscale research is broad, challenging, and interdepartmental, undergraduate through Ph.D. level students and faculty have combined efforts to attack the special problems related to building nanoscale smart materials. This paper gives an overview of the work being performed to manufacture polymer nanocomposite materials starting from nanotube synthesis through to device fabrication and testing. Synthesis is performed using an EasyTube Nanofurnace, functionalization is done using plasma coating, dispersion using rotary mixing and ultrasonication, and processing using vacuum and pressure casting. Reinforced polymers, a carbon nanotube solid polymer electrolyte actuator, and piezoresistive sensors are being developed for several potential applications. The materials produced indicate that carbon nanotube hybrid smart materials may become a new class of smart material with unique properties and applications, but much work still needs to be done to realize their full potential.

Jain, Sachin B.; Kang, Phil; Yun, Yeo-Heung; He, Tony; Pammi, Sri Laxmi; Muskin, Atul; Narasimhadevara, Suhasini; Hurd, Douglas; Schulz, Mark J.; Chase, Jennifer; Subramaniam, Srinivas; Shanov, Vesselin; Boerio, F. J.; Shi, Donglu; Gilliland, Rob; Mast, David; Sloan, Chris

2004-07-01

417

Piezoresistive effect in carbon nanotube fibers.  

PubMed

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

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

2014-11-25

418

Electronic band structure of isolated and bundled carbon nanotubes  

Microsoft Academic Search

We study the electronic dispersion in chiral and achiral isolated nanotubes as well as in carbon nanotube bundles. The curvature of the nanotube wall is found not only to reduce the band gap of the tubes by hybridization, but also to alter the energies of the electronic states responsible for transitions in the visible energy range. Even for nanotubes with

S. Reich; C. Thomsen; P. Ordejón

2002-01-01

419

ccsd00001984, Selective production of metallic carbon nanotubes  

E-print Network

ccsd­00001984, version 1 ­ 18 Oct 2004 Selective production of metallic carbon nanotubes Yasushi- type nanotubes (metallic character) evaluated using the previous Huckel-Poisson method can be applied at the tip of a nanotube in a realistic system. Setting the cross-section of a nanotube and the external #12

420

Anomalous aharonov-bohm gap oscillations in carbon nanotubes.  

PubMed

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

Sangalli, Davide; Marini, Andrea

2011-10-12

421

Lipid nanoscaffolds in carbon nanotube arrays  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

422

Exposure to Carbon Nanotube Material: Assessment of Nanotube Cytotoxicity using Human Keratinocyte Cells  

Microsoft Academic Search

Carbon nanotubes are new members of carbon allotropes similar to fullerenes and graphite. Because of their unique electrical, mechanical, and thermal properties, carbon nanotubes are important for novel applications in the electronics, aerospace, and computer industries. Exposure to graphite and carbon materials has been associated with increased incidence of skin diseases, such as carbon fiber dermatitis, hyperkeratosis, and naevi. We

Anna Shvedova; Vincent Castranova; Elena Kisin; Diane Schwegler-Berry; Ashley Murray; Vadim Gandelsman; Andrew Maynard; Paul Baron

2003-01-01

423

g-tensor control in bent carbon nanotube quantum dots  

NASA Astrophysics Data System (ADS)

We demonstrate gate control of the electronic g tensor in single and double quantum dots formed along a bend in a carbon nanotube. From the dependence of the single-dot excitation spectrum on magnetic field magnitude and direction, we extract spin-orbit coupling, valley coupling, and spin and orbital magnetic moments. Gate control of the g tensor is measured using the splitting of the Kondo peak in conductance as a sensitive probe of Zeeman energy. In the double-quantum-dot regime, the magnetic field dependence of the position of cotunneling lines in the two-dimensional charge stability diagram is used to infer the real-space positions of the two dots along the nanotube.

Lai, R. A.; Churchill, H. O. H.; Marcus, C. M.

2014-03-01

424

Functionalized multiwall carbon nanotubes incorporated polymer\\/fullerene hybrid photovoltaics  

Microsoft Academic Search

Multiwall carbon nanotubes are introduced into poly(3-hexylthiophene) and {[}6,6] phenyl C(61) butyric acid methyl fullerene, bulk heterojunction organic photovoltaic devices. Utilization of nanotubes requires chemical modifications for compatibility with solution processable photovoltaics. Better dispersions of carbon nanotubes in organic solvents are achieved by acid functionalization of tubes. Pristine and acid treated multiwall carbon nanotubes have been incorporated into the photoactive

N. A. Nismy; A. A. D. T. Adikaari; S. R. P. Silva

2010-01-01

425

Functionalized multiwall carbon nanotubes incorporated polymer\\/fullerene hybrid photovoltaics  

Microsoft Academic Search

Multiwall carbon nanotubes are introduced into poly(3-hexylthiophene) and [6,6] phenyl C61 butyric acid methyl fullerene, bulk heterojunction organic photovoltaic devices. Utilization of nanotubes requires chemical modifications for compatibility with solution processable photovoltaics. Better dispersions of carbon nanotubes in organic solvents are achieved by acid functionalization of tubes. Pristine and acid treated multiwall carbon nanotubes have been incorporated into the photoactive

N. A. Nismy; A. A. D. T. Adikaari; S. R. P. Silva

2010-01-01

426

Phase Behavior of Carbon Nanotube Suspensions  

NASA Astrophysics Data System (ADS)

We study the phase behavior of nanotube suspensions stabilized by surfactants or amphiphilic polymers. The control of the composition of the solutions allows the interaction potential between the nanotubes to be finely tuned. As a consequence, it is possible to quantitatively analyze important phenomena such as percolation or liquid crystalline phase transitions. In particular, we describe how the percolation of rod-like particles is quantitatively decreased in the presence of attractive interactions (1). We show that rod-like particles respond much more strongly than spheres to attractive interactions; strengthening thereby the technological interest of carbon nanotubes to achieve low percolation thresholds for electrostatic dissipation or electromagnetic shielding. By contrast, carbon nanotubes which experience repulsive interactions can spontaneously order and form liquid crystalline solutions (2). Aligning and packing nanotubes is a major challenge to obtain macroscopic materials with improved properties. We will briefly discuss at the end of the presentation, our latest results concerning the fabrication of fibers aligned nanotubes (3). In particular, we will present new treatments of these fibers which lead to unusual mechanical properties and shape memory effects with giant stress recovery (4). *B. Vigolo, C. Coulon, M. Maugey, C. Zakri, P. Poulin, Science 2005. *S. Badaire, C. Zakri, M. Maugey, A. Derr'e, J. Barisci, G. Wallace, P. Poulin, Adv. Mat. 2005. *P. Miaudet, M. Maugey, A. Derr'e, V. Pichot, P. Launois, P. Poulin, C. Zakri, Nanoletters 2005. *P. Miaudet, A. Derr'e, M. Maugey, C. Zakri, P. Poulin, in preparation.

Poulin, Philippe

2006-03-01

427

Compressed carbon nanotubes: A family of new multifunctional carbon allotropes  

PubMed Central

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

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

2013-01-01

428

Laser ablative synthesis of carbon nanotubes  

DOEpatents

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

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

2010-03-02

429

A quenchable superhard carbon phase synthesized by cold compression of carbon nanotubes  

E-print Network

A quenchable superhard carbon phase synthesized by cold compression of carbon nanotubes Zhongwu) A quenchable superhard high-pressure carbon phase was synthe- sized by cold compression of carbon nanotubes. Carbon nanotubes were placed in a diamond anvil cell, and x-ray diffraction measure- ments were conducted

Downs, Robert T.

430

Mechanically interlocked single-wall carbon nanotubes.  

PubMed

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

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

2014-05-19

431

Titania carbon nanotube composites for enhanced photocatalysis  

NASA Astrophysics Data System (ADS)

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

Pyrgiotakis, Georgios

432

Improved Method of Purifying Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

Delzeit, Lance D.

2004-01-01

433

Activated carbon catalyzing the formation of carbon nanotubes  

Microsoft Academic Search

Activated carbon (AC), a common carbon material, is employed as catalyst to synthesize carbon nanotubes (CNTs) through chemical vapor deposition (CVD) and detonation-assisted CVD methods. The results show AC can effectively catalyze CNT formation. From the microscopic observations on morphologies and structures of the formed intermediates, it is found that carbon-catalyzed CNT formation follows particle-wire-tube stepwise evolution mechanism, in which

Jinling Song; Shouai Feng; Jianghong Zhao; Jianfeng Zheng; Zhenping Zhu

2010-01-01

434

Organic Solvent Dispersions of Single-Walled Carbon Nanotubes: Toward Solutions of Pristine Nanotubes  

E-print Network

LETTERS Organic Solvent Dispersions of Single-Walled Carbon Nanotubes: Toward Solutions of Pristine Nanotubes Kevin D. Ausman, Richard Piner, Oleg Lourie, and Rodney S. Ruoff* Department of Physics/dispersion of pristine single-walled carbon nanotubes (SWCNTs). Five solvents, all featuring high electron pair donicity

Ben-Yakar, Adela

435

Improving photovoltaic properties by incorporating both single walled carbon nanotubes and functionalized multiwalled carbon nanotubes  

Microsoft Academic Search

Single-walled carbon nanotubes (SWCNTs) and functionalized multiwalled carbon nanotubes (f-MWCNTs) are introduced together for photovoltaic application in a poly(3-octylthiophene)\\/n-Si heterojunction solar cell. The performance of the device was improved by manyfold by the incorporation of both SWCNTs and f-MWCNTs. The open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF), and power conversion efficiency (?) were 0.44 V,

Ishwor Khatri; Sudip Adhikari; Hare Ram Aryal; Tetsuo Soga; Takashi Jimbo; Masayoshi Umeno

2009-01-01

436

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...

437

Carbon nanotube networks in epoxy composites and aerogels  

Microsoft Academic Search

This thesis describes the properties of carbon nanotube networks in epoxy composites and in novel carbon nanotube aerogels. SWNT Epoxy composites were created using a new procedure that enabled us to control SWNT concentration and dispersion quality in the composite. The composites exhibited percolation-like electrical conductivity with threshold volume fractions in the semi-dilute nanotube concentration regime. The observed electrical conductivites

Mateusz B. Bryning

2007-01-01

438

Carbon nanotubes as photoacoustic molecular imaging agents in living mice  

E-print Network

Carbon nanotubes as photoacoustic molecular imaging agents in living mice ADAM DE LA ZERDA1 not shown to target a diseased site in living subjects. Here we show that single-walled carbon nanotubes of tumours. Intravenous administration of these targeted nanotubes to mice bearing tumours showed eight times

Khuri-Yakub, Butrus T. "Pierre"

439

Simulations of nanosensors based on single walled carbon nanotubes  

E-print Network

Simulations of nanosensors based on single walled carbon nanotubes Polina Pine1, Yuval E. Yaish2. The potential of single-walled carbon nanotubes as mass sensors is examined. The change in mass leads to proportional changes in the nanotube vibrational frequencies, which are monitored during atomistic simulations

Adler, Joan

440

Carbon nanotubes adhesion and nanomechanical behavior from peeling force spectroscopy  

E-print Network

Carbon nanotubes adhesion and nanomechanical behavior from peeling force spectroscopy Julien December 17, 2010 Abstract Applications based on Single Walled Carbon Nanotube (SWNT) are good example such as adhesion energy per unit length, curvature and bending rigidity of the nanotube. A complete picture

Boyer, Edmond

441

Absorption spectroscopy of individual single-walled carbon nanotubes  

E-print Network

Absorption spectroscopy of individual single-walled carbon nanotubes Stéphane Berciaud,a Laurent-walled carbon nanotubes (SWNTs) lead to heterogeneous samples containing mixtures of metallic and semiconducting species with a variety of lengths and defects. Optical detection at the single nanotube level should thus

Boyer, Edmond

442

Stepwise Quenching of Exciton Fluorescence in Carbon Nanotubes  

E-print Network

1 Stepwise Quenching of Exciton Fluorescence in Carbon Nanotubes by Single Molecule Reactions with individual single-walled carbon nanotubes are observed, and luminescence quenching analysis reveals the diffusional range of excitons in semiconducting nanotubes. *To whom correspondence should be addressed

Paris-Sud XI, Université de

443

Electrochemical and Raman measurements on single-walled carbon nanotubes  

E-print Network

Electrochemical and Raman measurements on single-walled carbon nanotubes M. Stoll a,*, P performed on a carbon nanotube mat as a working electrode using different salt solutions. The gravimetric capacitance of the nanotube material was estimated and its effective surface area was de- termined in a purely

Nabben, Reinhard

444

Carbon Nanotubes as Ultrahigh Quality Factor Mechanical Resonators  

E-print Network

Carbon Nanotubes as Ultrahigh Quality Factor Mechanical Resonators Andreas K. Hu¨ttel, Gary A mode of suspended carbon nanotubes at millikelvin temperatures by measuring the single- electron tunneling current. The suspended nanotubes are actuated contact-free by the radio frequency electric field

445

Carbon Nanotubes for Thermoacoustic Contrast Enhancement Preliminary Results  

E-print Network

Carbon Nanotubes for Thermoacoustic Contrast Enhancement ­ Preliminary Results Darrin Byrda., Milwaukee, WI 53211, USA ABSTRACT The unique electrical properties of Single-Walled Carbon Nanotubes make that nanotubes are capable of greatly increasing a material's absorption of electromagnetic radiation. We

Patch, Sarah

446

Visualizing the Local Optical Response of Semiconducting Carbon Nanotubes to  

E-print Network

Visualizing the Local Optical Response of Semiconducting Carbon Nanotubes to DNA-Wrapping Huihong ABSTRACT We studied the local optical response of semiconducting single-walled carbon nanotubes to wrapping-field images of single nanotubes reveal large DNA-wrapping-induced red shifts of the exciton energy

Novotny, Lukas

447

Quantum rotation of hydrogen in single-wall carbon nanotubes  

E-print Network

Quantum rotation of hydrogen in single-wall carbon nanotubes C.M. Brown a,b , T. Yildirim b , D containing single-wall carbon nanotubes. These materials have attracted considerable interest recently due the ortho±para conversion of physisorbed hydrogen in a nanotube containing soot loaded with hydrogen. From

Yildirim, Taner

448

Manipulation and Imaging of Individual Single-Walled Carbon Nanotubes  

E-print Network

Manipulation and Imaging of Individual Single-Walled Carbon Nanotubes with an Atomic Force Microscope** By Henk W. C. Postma, Allard Sellmeijer, and Cees Dekker* Carbon nanotubes[1] have attracted-walled nanotubes,[3±5] the prototype single-walled tubes are much more difficult to study since their diameter

449

Scanning Tunneling Microscopy of DNA-Wrapped Carbon Nanotubes  

E-print Network

Scanning Tunneling Microscopy of DNA-Wrapped Carbon Nanotubes Dzmitry A. Yarotski,*, Svetlana V ABSTRACT We employ scanning tunneling microscopy (STM) to reveal the structure of DNA-carbon nanotube simulations. STM images show strands of DNA wrapping around (6,5) nanotubes at 63° angle with a coiling period

Tretiak, Sergei

450

Ultra LowVoltage Delay Locked Loop Using Carbon Nanotubes  

E-print Network

Ultra LowVoltage Delay Locked Loop Using Carbon Nanotubes J.S. Ajit Northeastern University Dept, MA 02115 E-mail: ybk@ece.neu.edu AbstractCarbon Nanotube FET technology is investigated frequency range from 330 MHz to 10 GHz. The characteristics is dependent on the nanotube parameters

Ayers, Joseph

451

Carbon Nanotubes and Semiconductor Nanowires for Active Matrix Backplanes.  

E-print Network

Carbon Nanotubes and Semiconductor Nanowires for Active Matrix Backplanes. D. Pribat, C. S and P. Legagneux Thales Research & Technology, 91767 Palaiseau, France ABSTRACT Carbon nanotubes (CNTs nanotubes (CNTs) and semiconductor nanowires (essentially Si and Ge). We will also emphasise the possible

Paris-Sud XI, Université de

452

Sustained Mechanical Self-Oscillations in Carbon Nanotubes  

E-print Network

Sustained Mechanical Self-Oscillations in Carbon Nanotubes Jeffrey A. Weldon, Benjamin Alema-power electronics. Here we demonstrate controllable, sustained self-oscillations in singly clamped carbon nanotubes nanotubes, oscillators, self-oscillation, NEMS, field emission N anoelectromechanical systems1 (NEMS) based

Zettl, Alex

453

Excitons and Peierls Distortion in Conjugated Carbon Nanotubes  

E-print Network

Excitons and Peierls Distortion in Conjugated Carbon Nanotubes Sergei Tretiak,*, Svetlana Kilina investigate coupled excitonic and vibrational effects in carbon nanotubes using a time-dependent Hartree the entire nanotube, particularly in large-radius CNTs. However, we demonstrate that vibrational relaxation

Tretiak, Sergei

454

Estimating the Raman cross sections of single carbon nanotubes  

E-print Network

Estimating the Raman cross sections of single carbon nanotubes Johanna E. Bohn, Pablo G. Etchegoin's) of individual carbon nanotubes is measured for 633 and 785 nm laser excitations, respectively. This is shown measurements of individual nanotubes at 633 nm ex- citation. We find typical values of differential cross

Maruyama, Shigeo

455

Screening of Excitons in Single, Suspended Carbon Nanotubes  

E-print Network

Screening of Excitons in Single, Suspended Carbon Nanotubes Andrew G. Walsh, A. Nickolas Vamivakas spectroscopy of single carbon nanotubes suspended across trenches displays red-shifts of up to 30 me nanotubes (CNT)1-5 has been experimen- tally confirmed by recent two-photon experiments.6-8 With binding

456

A multiscale projection method for the analysis of carbon nanotubes  

E-print Network

A multiscale projection method for the analysis of carbon nanotubes Dong Qian a,*, Gregory J of carbon nanotube systems. The multiscale coupled governing equations are first derived based nanotube structures. To our knowledge, this is the first multiscale post-buckling analysis presented

Qian, Dong

457

Time, temperature, and load: The flaws of carbon nanotubes  

E-print Network

Time, temperature, and load: The flaws of carbon nanotubes Rodney S. Ruoff* Department to the nucleation of defects. In a recent issue of PNAS, Dumitrica et al. (3) consider carbon nanotubes (CNTs) and, boron nitride, and metal dichalcogenide nanotubes (among others), and single-crystal inor- ganic

458

Carbon nanotube complementary wrap-gate transistors.  

PubMed

Among the challenges hindering the integration of carbon nanotube (CNT) transistors in digital technology are the lack of a scalable self-aligned gate and complementary n- and p-type devices. We report CNT transistors with self-aligned gates scaled down to 20 nm in the ideal gate-all-around geometry. Uniformity of the gate wrapping the nanotube channels is confirmed, and the process is shown not to damage the CNTs. Further, both n- and p-type transistors were realized by using the appropriate gate dielectric-HfO2 yielded n-type and Al2O3 yielded p-type-with quantum simulations used to explore the impact of important device parameters on performance. These discoveries not only provide a promising platform for further research into gate-all-around CNT devices but also demonstrate that scalable digital switches with realistic technological potential can be achieved with carbon nanotubes. PMID:23638708

Franklin, Aaron D; Koswatta, Siyuranga O; Farmer, Damon B; Smith, Joshua T; Gignac, Lynne; Breslin, Chris M; Han, Shu-Jen; Tulevski, George S; Miyazoe, Hiroyuki; Haensch, Wilfried; Tersoff, Jerry

2013-06-12

459

Coupling of carbon and peptide nanotubes.  

PubMed

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. PMID:24471492

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

2014-02-12

460

Magnetic Nanotubes: Synthesis, Properties, and Applications  

Microsoft Academic Search

This article presents a comprehensive review of recent progress of research dedicated to magnetic nanotubes (MNTs). The review mainly covers the recent achievements in the syntheses, properties, and applications of MNTs. After introducing the significance of MNTs and the magnetic characteristics of elements in the periodic table, the article starts with a brief overview of the existing fabrication pathways for

Yixing Ye; Baoyou Geng

2012-01-01

461

Fluorecently labeled bionanotransporters of nucleic acid based on carbon nanotubes  

E-print Network

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

Novopashina, D S; Venyaminova, A G

2012-01-01

462

Grafting carbon nanotubes onto carbon fiber by use of dendrimers  

Microsoft Academic Search

A novel method is developed for grafting carbon nanotubes (CNTs) onto the carbon fiber (CF) surface by use of dendrimers. CF surface is functionalized by an adsorbed dendrimers layer. After an oxidation treatment, CNTs with carboxyl, carbonyl or hydroxyl groups are grafted onto the amino-functionalized CFs via chemical interactions. Homogeneous multi-scale structures with different CNT densities and lengths are gained

Lei Mei; Xiaodong He; Yibin Li; Rongguo Wang; Chao Wang; Qingyu Peng

2010-01-01

463

Carbon nanotube–cement composites: A retrospect  

Microsoft Academic Search

Although ordinary Portland cement (OPC) is widely used in the construction industry, its weak tensile strength, to some extent, limits its application. A carbon nanotube (CNT), on the other hand, has outstanding mechanical properties with a tensile strength of 63 GPa and Young's modulus of 1 TPa, making it a candidate as nano-scale reinforcements in OPC. Past research studies have

S. J. Chen; F. G. Collins; A. J. N. Macleod; Z. Pan; W. H. Duan; C. M. Wang

2011-01-01

464

Vacuum microelectronics applications using carbon nanotube cathodes  

Microsoft Academic Search

We will present the recent advances in carbon nanotube bundle array based field emission electron source development. These cathodes are being applied for developing new vacuum microelectronic devices. Some application issues, cathode life time, current density influencing factors, and a novel electrode integration technique will be described.

H. M. Manohara; R. Toda; R. H. Lin; A. Liao; R. Kowalczyk; A. B. Kaul; M. M. Mojarradi

2008-01-01

465

Carbon Nanotubes as Schottky Barrier Transistors  

Microsoft Academic Search

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

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

2002-01-01

466

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

E-print Network

aligned. Here we report results of terahertz (THz) transmission measurements on a strongly absorbing filmCarbon Nanotube Terahertz Polarizer Lei Ren,, Cary L. Pint,,§,| Layla G. Booshehri,, William D as an excellent terahertz linear polarizer. There is virtually no attenuation (strong absorption) when

Kono, Junichiro

467

Carbon Nanotube Inter and Intramolecular Logic Gates  

Microsoft Academic Search

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

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

2001-01-01

468

Single-walled carbon nanotube electronics  

Microsoft Academic Search

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

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

2002-01-01

469

Effective models for excitons in carbon nanotubes  

E-print Network

We analyse the low lying spectrum of a model of excitons in carbon nanotubes. Consider two particles with an attractive Coulomb self-interaction, placed on an infinitely long cylinder. If the cylinder radius becomes small, the low lying spectrum is well described by a one-dimensional effective Hamiltonian which is exactly solvable.

Horia D. Cornean; Pierre Duclos; Benjamin Ricaud

2006-05-04