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1

Novel carbon nanotube iron oxide magnetic nanocomposites  

Microsoft Academic Search

A novel magnetic nanocomposite of ?-Fe2O3 nanoparticles decorated multiwalls carbon nanotubes (MWNTs) was synthesized for the first time by a simple chemistry precipitation method. The structure and morphology of the composite was characterized by X-ray powder diffractometer (XRD), TEM and EDS. The results of XRD and TEM show that ?-Fe2O3 nanoparticles is immobilized on the side wall of the MWNTs,

Cao Huiqun; Zhu Meifang; Li Yaogang

2006-01-01

2

Magnetic Properties of Carbon Nanotubes with Low Content of Fe  

Microsoft Academic Search

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

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

2010-01-01

3

Magnetostatic interactions between carbon nanotubes filled with magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

The magnetostatic interactions between carbon nanotubes filled with magnetic particles have been experimentally and theoretically studied. By making nanotubes uniformly magnetized, one eliminates the attraction caused by periodicity of nanoparticles in magnetic chains. The discreteness of individual nanoparticles in the nanoneedles is not observed and these nanoneedles interact by their magnetic poles. Since the attraction/repulsion events are predictable, the suspensions of magnetic nanotubes are attractive candidates for active elements in changeable diffraction gratings, filters, and polarizers.

Kornev, Konstantin G.; Halverson, Derek; Korneva, Guzeliya; Gogotsi, Yury; Friedman, Gary

2008-06-01

4

Novel carbon nanotube iron oxide magnetic nanocomposites  

NASA Astrophysics Data System (ADS)

A novel magnetic nanocomposite of ?-Fe2O3 nanoparticles decorated multiwalls carbon nanotubes (MWNTs) was synthesized for the first time by a simple chemistry precipitation method. The structure and morphology of the composite was characterized by X-ray powder diffractometer (XRD), TEM and EDS. The results of XRD and TEM show that ?-Fe2O3 nanoparticles is immobilized on the side wall of the MWNTs, the size of most of the particle is <5 nm.The EDS analysis shows that the atomic ratio of Fe to O is 2:3. The magnetization curves of the MWNTs and ?-Fe2O3 decorated MWNTs were measured by VSM at room temperature, which indicate that the saturated magnetization (Ms), remanence (Mr) and coercivity (Hc) of the decorated MWNTs are much larger than those of MWNTs, and the decorated MWNTs exhibit well magnetic properties.

Huiqun, Cao; Meifang, Zhu; Yaogang, Li

2006-10-01

5

Metallic carbon nanotube quantum dots under magnetic fields  

Microsoft Academic Search

Quantum dots made of individual metallic carbon nanotubes are theoretically studied under the influence of a magnetic field applied in the axial direction. After assessing the mechanical stability of the heterostructure by Monte Carlo simulations, the dependence of the electronic properties on the size of the nanotube quantum dot and applied magnetic field has been investigated within the Peierls approximation

C. G. Rocha; A. Latgé; L. Chico

2005-01-01

6

Transport and Magnetism in Template Synthesized Hydrogenated Multiwalled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

In this work, we synthesize highly disordered carbon nanotubes by CVD in porous alumina templates. We show that, due to the disorder in the nanotubes, they can easily be made to uptake hydrogen by annealing. We show that this induces ferromagnetism in the nanotubes, and we perform a magnetic study. We also measure the transport properties of the nanotubes. First, we find a rate dependent hysteretic magnetoresistance. We explain the rate dependence through strong magneto-viscosity effects, and we attribute the hysteresis to anisotropic magnetoresistance. We also discover a magnetic field-driven temperature dependent transition from positive to negative magnetoresistance in the ferromagnetic nanotubes that is not observed in similarly disordered un-hydrogenated carbon nanotubes. We attempt to explain this behavior by considering it an order-disorder transition described by the Bright model due to several scattering pathways, that are present in the ferromagnetic nanotubes that are not present in the non-ferromagnetic tubes.

Friedman, Adam; Chun, Hyunkyung; Heiman, Donald; Jung, Yung Joon; Menon, Latika

2009-03-01

7

Electronic response properties of carbon nanotubes in magnetic fields.  

PubMed

Magnetic linear response properties for achiral and chiral carbon nanotubes were investigated with first-principles electronic structure methods. We have computed the magnetic shielding inside and outside the tubes originating from electronic current densities induced by the application of an external magnetic field. This electronic response of the nanotubes was analyzed for external magnetic fields both parallel and perpendicular to the tube axis. The magnetic screening would be experienced by guest molecules inside the tubes, measurable by NMR spectroscopy on isotopically labeled samples. Special attention is given to chiral nanotubes, in which longitudinal fields induce a non-zero longitudinal current density and thus tangential magnetic fields outside the tubes. PMID:19206596

Sebastiani, Daniel; Kudin, Konstantin N

2008-04-01

8

Structure and magnetism in carbon nanotubes including magnetic wire  

NASA Astrophysics Data System (ADS)

We have studied the electronic structure of the carbon nanotubes which include Fe atomic wire with using the density functional theory. As the stable geometries, we obtained the straight and zigzag wires, which have ferromagnetic and antiferromagnetic alignments, respectively. The antiferromagnets consists of the two ferromagnetic dimers which couple in antiparallel alignment. We presents the band dispersions and the density of states for the magnetic nanotubes. The electronic structure at the Fermi level consists of the Fe 3d and C 2p? states, which shows a strong hybridization between them.

Shiroishi, H.; Oda, T.; Sakashita, H.; Fujima, N.

2007-07-01

9

Synthesis of vertically aligned carbon nanotubes, magnetic nanotubes, and magnetic CNTs for cellular growth and detection  

NASA Astrophysics Data System (ADS)

The paper describes the synthesis of vertically aligned CNTs and the development of magnetic nanotube substrates for biological applications. The vertical alignment of the CNTs on a silicon substrate for the use in biological sensor systems has been explored. The preliminary experiments to determine the binding and growth of biological samples with CNTs have been described. The potential to use the CNTs as electrode for elctrical stimulation is explored. The growth of magnetic nanotubes and the possibility of utilizing them as scaffold for cellular growth is demonstrated. The paper also described the sythesis and development of the magnetic carbon nanotubes, combining the salient features of the CNTs and MNTs. All the nanotubes are optically charaterizd using SEM and TEM techniques. The magentization of the nanotubes are evaluated using the VSM. Cellular binding is determined using SEM and flourescent microscopy images.

Aatre, K.; Xie, J.; Chen, L. F.; Abraham, J. K.; Varadan, V. K.

2008-04-01

10

Magnetic force microscopy sensors using iron-filled carbon nanotubes  

SciTech Connect

Probes for magnetic force microscopy (MFM) were prepared by pinning iron-filled multiwall carbon nanotubes to conventional scanning force microscopy probes. These nanotube MFM probes reveal a great potential for high spatial resolution of both topography and magnetic stray field. The ends of the high aspect ratio iron nanowires within the nanotubes can be considered as stationary effective magnetic monopole moments which opens the possibility of quantitative stray field measurements in a straightforward manner. The carbon shells around the iron nanowires provide wear resistance and oxidation protection.

Winkler, Andreas; Muehl, Thomas; Menzel, Siegfried; Kozhuharova-Koseva, Radinka; Hampel, Silke; Leonhardt, Albrecht; Buechner, Bernd [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany)

2006-05-15

11

Magnetic properties of strained single-walled carbon nanotubes  

Microsoft Academic Search

Strong effects of uniaxial and torsional strains on the magnetic properties of single-walled carbon nanotubes have been investigated by tight binding calculations and the Green function analyses. The strain-induced peaks of susceptibility are found in the carbon nanotubes, and paramagnetic-diamagnetic transition takes place at certain strains. The critical magnetic flux for semiconductor-metal transition changes linearly with strains depending on the

Zhuhua Zhang; Wanlin Guo

2007-01-01

12

Magnetization of carbon-doped MgO nanotubes  

NASA Astrophysics Data System (ADS)

Using local spin-density-functional formalism, we study the occurrence of spin polarization in magnesium oxide nanotubes doped with carbon impurities. We find that carbon impurity acquires a magnetization caused by the 2p states partly filled and placed in forbidden gap of a MgO tube. According to our estimations, for carbon impurity replacing oxygen inside the MgO tube wall, the spin magnetization (at about 2?B per cell) is found. The results are used in discussion of the new approach to the engineering of magnetic nanotubes, namely, the magnetization of nonmagnetic tubes induced by nonmagnetic impurities.

Shein, Igor R.; Enyashin, Andrey N.; Ivanovskii, Alexander L.

2007-06-01

13

Magnetic and electronic properties of multiwall carbon nanotubes  

NASA Astrophysics Data System (ADS)

Multiwall carbon nanotubes were studied by dc magnetization and electron spin resonance (ESR) measurements. Hole doping is inferred from both the high-field dc susceptibility and ESR parameters complying favorably with the band model of two-dimensional graphite. Paramagnetic deviations are evinced on the diamagnetic susceptibility at weak fields and low temperatures, conforming qualitatively with the Aharonov-Bohm effect on the energy gap for magnetic field parallel to the tube axis. Comparison with theoretical predictions for ensembles of carbon nanotubes reveals appreciable differences, indicative of the diverse distribution of nanotubes as well as the presence of active doping.

Likodimos, V.; Glenis, S.; Guskos, N.; Lin, C. L.

2003-07-01

14

Magnetic Fractionation and Alignment of Single Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

We study mechanisms of single wall carbon nanotube (SWNT) alignment in a magnetic field. Through magnetic fractionation, we create SWNT suspensions with varying quantities of magnetic catalyst particles. The degree of tube alignment in magnetic fields up to 9 Tesla is quantified using polarized optical absorbance anisotropy. Continuous measurements of the nematic order parameter of these suspensions in variable magnetic fields provides a way to identify the origin of magnetic torques giving rise to nanotube alignment. Initial data suggests a transition from catalyst-driven to nanotube-anisotropy driven orientation as the catalyst fraction is reduced. We relate these results to observations of nanotube aggregation. This work has been supported by NSF through DMR-0203378, DMR-079909 and DGE-0221664, NASA through NAG8-2172, DARPA/ONR through N00014-01-1-0831, and SENS.

Islam, M. F.; Milkie, D. E.; Yodh, A. G.; Kikkawa, J. M.

2004-03-01

15

Neuroblastoma Cells Displacement by Magnetic Carbon Nanotubes  

Microsoft Academic Search

In this paper, as-produced multiwall carbon nanotubes (MWNTs) have been analyzed by scanning electron microscopy and energy dispersive X-ray spectrometry, revealing the presence of Fe, Al, and Zn residuals and impurities. MWNTs have then been dispersed in Pluronic F127 aqueous solution and used to seed neuroblastoma cell lines (HN9.10e and SH-SY5Y) for three days. We found that MWNTs interact with

V. Pensabene; O. Vittorio; V. Raffa; A. Ziaei; A. Menciassi; P. Dario

2008-01-01

16

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

17

Assemblies of magnetically aligned carbon nanotubes  

NASA Astrophysics Data System (ADS)

Macroscopic samples of highly aligned SWNTs have been produced by filtration in the presence of a 25 Tesla magnetic field. Alignment resulted from the difference in magnetic susceptibility between nanotubes parallel and perpendicular to the field. Polarized optical transmittance data on a colloidal suspension indicated that at 19 Tesla the alignment energy was (28 ± 3) times thermal energy at room temperature. The solid mats resulting from filtration exhibited anisotropic mechanical and optical properties. Unlike similar mats composed of unordered material, the aligned mats split preferentially along the magnetic field axis. This is consistent with a lack of reinforcing fibers perpendicular to this axis. Micro-Raman scattering showed a factor of (7 ± 2) difference in signal intensity for orientations parallel and perpendicular to the polarization of incident radiation. This novel, unusual material provides a macroscopic window to the properties of these nanoscale entities and paves the way for many potential applications.

Casavant, M. J.; Walters, D. A.; Qin, X. C.; Huffman, C. B.; Colbert, D. T.; Smalley, R. E.

2000-03-01

18

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.

19

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

Microsoft Academic Search

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

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

2006-01-01

20

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

2010-12-20

21

Microwave absorption in nanocomposite material of magnetically functionalized carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

22

Itinerant flat-band magnetism in hydrogenated carbon nanotubes.  

PubMed

We investigate the electronic and magnetic properties of hydrogenated carbon nanotubes using ab initio spin-polarized calculations within both the local density approximation (LDA) and the generalized gradient approximation (GGA). We find that the combination of charge transfer and carbon network distortion makes the spin-polarized flat-band appear in the tube's energy gap. Various spin-dependent ground state properties are predicted with the changes of the radii, the chiralities of the tubes, and the concentration of hydrogen. It is found that strain or external electric field can effectively modulate the flat-band spin-splitting and even induce an insulator-metal transition. PMID:19548640

Yang, Xiaoping; Wu, Gang

2009-06-23

23

Barkhausen jumps and related magnetic properties of iron nanowires encapsulated in aligned carbon nanotube bundles  

Microsoft Academic Search

Iron nanowires encapsulated in aligned carbon nanotube bundles show interesting magnetic properties. Besides the increased coercivity, Barkhausen jumps with 5 emu\\/g steps in magnetization are observed due to magnetization reversal or depinning of domains.

B. C Satishkumar; A Govindaraj; P. V Vanitha; Arup K Raychaudhuri; C. N. R Rao

2002-01-01

24

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.

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

2010-01-01

25

Comparative study of heavy metal ions sorption onto activated carbon, carbon nanotubes, and carbon-encapsulated magnetic nanoparticles  

Microsoft Academic Search

The paper presents the advantages and limitations of heavy metals sorption onto three different carbon materials: activated carbon, carbon nanotubes, and carbon-encapsulated magnetic nanoparticles. Studied carbon sorbents differed with the grain size, crystallinity, and active surface area, which were derived from electron microscopy, Raman spectroscopy, and methylene blue adsorption, respectively. Detailed sorption studies were based on two model metal ions,

Krystyna Pyrzy?ska; Micha? Bystrzejewski

2010-01-01

26

Structural anisotropy of magnetically aligned single wall carbon nanotube films  

NASA Astrophysics Data System (ADS)

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

Smith, B. W.; Benes, Z.; Luzzi, D. E.; Fischer, J. E.; Walters, D. A.; Casavant, M. J.; Schmidt, J.; Smalley, R. E.

2000-07-01

27

Magnetic Carbon Nanotubes: Materials Development and Property Characterization  

NASA Astrophysics Data System (ADS)

A versatile chemical method was used to fill multi-wall carbon nanotubes (MWCNTs) with ferromagnetic nanoparticles [1]. For the first time, pulsed laser deposition and magnetron DC sputtering were used to fill vertically aligned MWCNTs. The later approaches gave high-yield nanoparticle filling of MWCNTs. Samples were characterized by Electron Microscopy, Energy Dispersive Spectroscopy, M"ossbauer Spectroscopy, and magnetization measurements. M"ossbauer measurements on chemically impregnated MWCNTs clearly show the presence of atomic Fe as well as mixed phases of Fe nano-particles inside the tubes. Magnetization measurements on PLD-filled vertically aligned MWCNTs indicate reasonable coercivity. However, the magnetic anisotropy appears to be randomly oriented, suggesting polycrystalline sample. Acknowledgement: The research at Morgan State University was partially supported by the US ARL-WMRD (W1813LT-5006-7056). [1] D. Seifu, Y. Hijji, G. Hirsch, and S. P. Karna, J. Magn. Magn. Mat. 320, 312 (2008).

Seifu, Dereje; Karna, Shashi

2009-03-01

28

Lipase immobilized on magnetic multi-walled carbon nanotubes.  

PubMed

Magnetic iron oxide nanoparticles were loaded onto the surfaces of multiwalled carbon nanotubes (MWNTs) by the impregnation method. The obtained magnetic nanotubes were characterized with high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Yarrowia lipolytica lipase was covalently immobilized on the magnetic MWNTs (M-MWNTs). M-MWNT-lipase was characterized with XPS spectra and XRD patterns. The structural change of the immobilized lipase was analyzed through circular dichroism spectroscopy. M-MWNT-lipase was utilized for the resolution of (R, S)-1-phenyl ethanol in the organic solvent of heptane. Compared to the native lipase, the lipase immobilized on M-MWNTs has significantly improved its enzymatic activity for the resolution of (R, S)-1-phenyl ethanol in heptane. M-MWNT-lipase can be easily recovered after catalysis. In addition, the effect of sonication time on the catalytic activity was also investigated. It is found that, up to 30min sonication, the catalysis by M-MWNT-lipase is almost not affected. While, the catalytic activity of the native lipase is decreased with sonication time. PMID:22115533

Tan, Huishan; Feng, Wei; Ji, Peijun

2011-10-29

29

Increasing the length of single-wall carbon nanotubes in a magnetically enhanced arc discharge  

SciTech Connect

It is demonstrated that a magnetic field has a profound effect on the length of a single-wall carbon nanotube (SWCNT) synthesized in the arc discharge. The average length of SWCNT increases by a factor of 2 in discharge with magnetic field as compared with the discharge without magnetic field, and the yield of long nanotubes with lengths above 5 {mu}m also increases. A model of SWCNT growth on metal catalyst in arc plasma was developed. Monte-Carlo simulations confirm that the increase of the plasma density in the magnetic field leads to an increase in the nanotube growth rate and thus leads to longer nanotubes.

Keidar, Michael [Department of Mechanical and Aerospace Engineering, George Washington University, Washington, District of Columbia 20052 (United States); Levchenko, Igor; Ostrikov, Kostya [Plasma Nanoscience, School of Physics, The University of Sydney, Sydney, New South Wales 2006 (Australia); Arbel, Tamir [Department of Material Science, University of Michigan, Ann Arbor, Michigan 48109 (United States); Alexander, Myriam [Department of Geophysical Science, University of Chicago, Chicago, Illinois 60637 (United States); Waas, Anthony M. [Department of Aerospace Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2008-01-28

30

Magnetic lymphatic targeting drug delivery system using carbon nanotubes.  

PubMed

By controlling size, nanoparticles can be effectively taken up into lymphatics. On this basis, various nanoparticles have been investigated for transporters of chemotherapeutic pharmaceuticals, but only a few were retained in the draining lymph node. Here, we present a technology using a magnetic carbon nanotubes (MNTs) delivery system, and it may be possible to facilitate the targeted delivery of drugs in the lymphatic tissue more effectively. Chemotherapeutic agents were incorporated into the pores of functionalized MNTs synthesized with a layer of magnetite nanoparticles on the inner surface of the nanotubes. To improve drug delivery to cancer cells in the lymph nodes, individualized MNTs were noncovalently functionalized by folic acid (FA). By using an externally placed magnet to guide the drug matrix to the regional targeted lymph nodes, the MNTs can be retained in the draining targeted lymph nodes for several days and continuously release chemotherapeutic drugs. Selective killing of tumor cells overexpressing the folate receptors (FRs) in the lymph nodes can be achieved, as FR is overexpressed across a broad spectrum of human tumors. PMID:17910909

Yang, Feng; Fu, De Liang; Long, Jiang; Ni, Quan Xing

2007-10-01

31

Effect of a magnetic field on high-harmonic generation by carbon nanotubes.  

PubMed

We consider a metallic single-walled carbon nanotube under the influence of the combination of laser and static magnetic fields. We study the nonlinear motion of pi electrons in metallic carbon nanotubes driven by external fields, and the induced current spectrum has been analyzed. High-harmonic generation in the presence of a transverse magnetic field is studied theoretically. Numerical calculations show that the plateau is extended to higher harmonics owing to the presence of magnetic field. PMID:19488161

Khosravi, H; Daneshfar, N; Bahari, A

2009-06-01

32

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

PubMed

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

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

2011-07-21

33

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

Microsoft Academic Search

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

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

2003-01-01

34

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

2013-06-06

35

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

36

Characterization of magnetic guar gum-grafted carbon nanotubes and the adsorption of the dyes  

Microsoft Academic Search

The hydrophobicity of carbon nanotubes (CNTs) limits their extensive application. The hydrophilicity and biocompatibility of CNTs can be improved by modifying them with biopolymers. As a natural biopolymer, guar gum (GG) was covalently grafted on the surfaces of multiwall carbon nanotube (MWCNT) to obtain GG–MWCNT composite. Then iron oxide nanoparticles were synthesized on the GG–MWCNT to prepare the magnetic GG–MWCNT–Fe3O4.

Li Yan; Peter R. Chang; Pengwu Zheng; Xiaofei Ma

37

Electrical Transport through Single-Wall Carbon Nanotubes in Perpendicular Oriented Magnetic Fields  

Microsoft Academic Search

Individual thin Single-Walled Carbon Nanotubes bundles were connected to noble metal leads with low contact resistance between tube and metal. Electrical transport measurements on these devices are presented, performed at temperatures of about 50 mK in a magnetic field perpendicular to the Single-Walled Carbon Nanotubes symmetry axis. In these measurements we have investigated the dependence of the electrical transport on

V. Krstic; J. Weis; S. Roth

2002-01-01

38

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

Microsoft Academic Search

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

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

2007-01-01

39

Magnetic carbon nanotubes: synthesis by electrostatic self-assembly approach and application in biomanipulations.  

PubMed

Magnetic multiwalled carbon nanotubes (MWNTs) were facilely prepared by the electrostatic self-assembly approach. Poly(2-diethylaminoethyl methacrylate) (PDEAEMA) was covalently grafted onto the surfaces of MWNTs by MWNT-initiated in situ atom transfer radical polymerization (ATRP) of 2-diethylaminoethyl methacrylate (DEAEMA). The PDEAEMA-grafted MWNTs were quaternized with methyl iodide (CH(3)I), resulting in cationic polyelectrolyte-grafted MWNTs (MWNT-PAmI). Magnetic iron oxide (Fe(3)O(4)) nanoparticles were loaded onto the MWNT surfaces by electrostatic self-assembling between MWNT-PAmI and Fe(3)O(4), affording magnetic nanotubes. The assembled capability of the nanoparticles can be adjusted to some extent by changing the feed ratio of Fe(3)O(4) to MWNT-PAmI. The obtained magnetic nanotubes were characterized with TEM, EDS, STEM, and element mapping analyses. TEM and EDS measurements confirmed the nanostructures and the components of the resulting nanoobjects. The magnetic nanotubes were assembled onto sheep red blood cells in a phosphate buffer solution, forming magnetic cells. The blood cells attached with or without magnetic nanotubes can be selectively manipulated in a magnetic field. These results promise a general and efficient strategy to magnetic nanotubes and the fascinating potential of such magnetic nanoobjects in applications of bionanoscience and technology. PMID:16599489

Gao, Chao; Li, Wenwen; Morimoto, Hisao; Nagaoka, Yutaka; Maekawa, Toru

2006-04-13

40

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

NASA Astrophysics Data System (ADS)

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

Konabe, Satoru; Okada, Susumu

2011-02-01

41

Spin dependent transport through a carbon nanotube quantum dot in magnetic field  

Microsoft Academic Search

Spin-polarized transport through a carbon nanotube quantum dot in the Kondo regime is studied by the equation of motion method. Magnetic field perpendicular to the tube axis breaks the spin degeneracy, whereas axial field breaks both the orbital and spin degeneracies. A strong magnetic field anisotropy of conductance and anisotropy of its spin polarization is observed. We propose a new

D. Krychowski; S. Lipi?ski; S. Krompiewski

2007-01-01

42

Electrical and thermal transport properties of magnetically aligned single wall carbon nanotube films  

NASA Astrophysics Data System (ADS)

Dense, thick films of aligned single wall carbon nanotubes and nanotube ropes have been produced by filtration/deposition from suspension in strong magnetic fields. Electrical resistivity exhibits moderate anisotropy with respect to the alignment axis, while the thermopower is the same when measured parallel or perpendicular to this axis. Both parameters have identical temperature dependencies in the two orientations. Thermal conductivity in the parallel direction exceeds 200 W/mK, within a decade of graphite.

Hone, J.; Llaguno, M. C.; Nemes, N. M.; Johnson, A. T.; Fischer, J. E.; Walters, D. A.; Casavant, M. J.; Schmidt, J.; Smalley, R. E.

2000-07-01

43

Nonlocal elasticity based magnetic field affected vibration response of double single-walled carbon nanotube systems  

NASA Astrophysics Data System (ADS)

The behaviour of carbon nanotubes in a magnetic field has attracted considerable attention in the scientific community. This paper reports the effects of a longitudinal magnetic field on the vibration of a magnetically sensitive double single-walled carbon nanotube system (DSWNTS). The two nanotubes of the DSWNTS are coupled by an elastic medium. The dynamical equations of the DSWNTS are derived using nonlocal elasticity theory. The two nanotubes are defined as an equivalent nonlocal double-Euler-Bernoulli beam system. Governing equations for nonlocal bending-vibration of the DSWNTS under a longitudinal magnetic field are derived considering the Lorentz magnetic force obtained from Maxwell's relation. An analytical method is proposed to obtain nonlocal natural frequencies of the DSWNTS. The influence of (i) nanoscale effects and (ii) strength of longitudinal magnetic field on the synchronous and asynchronous vibration phase of the DSWNTS is examined. Nonlocal effects with and without the effect of magnetic field are illustrated. Results reveal the difference (quantitatively) by which the longitudinal magnetic field affects the nonlocal frequency in the synchronous and asynchronous vibration modes of a DSWNTS.

Murmu, T.; McCarthy, M. A.; Adhikari, S.

2012-06-01

44

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

PubMed

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

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

2013-05-21

45

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

46

Chromium removal by combining the magnetic properties of iron oxide with adsorption properties of carbon nanotubes  

Microsoft Academic Search

The adsorption features of multiwall carbon nanotubes (MWCNTs) with the magnetic properties of iron oxides have been combined in a composite to produce a magnetic adsorbent. Composites of MWCNT\\/nano-iron oxide were prepared, and were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FTIR). XRD suggests that the magnetic phase formed is maghemite

V. K. Gupta; Shilpi Agarwal; Tawfik A. Saleh

2011-01-01

47

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

48

Magnetic field dependence of Coulomb oscillations in metal\\/multi-wall carbon nanotube\\/metal structures  

Microsoft Academic Search

We have studied magnetic field dependence of electron transport in highly resistive metal-on-tube metal\\/multi-wall carbon nanotube\\/metal structures. Current peaks due to Coulomb oscillations shift in a complex manner. The observed behavior is well reproduced by numerical calculation of the level shift due to the Landau level formation.

Akinobu Kanda; Seiji Uryu; Kazuhito Tsukagoshi; Youiti Ootuka; Yoshinobu Aoyagi

2002-01-01

49

Structure and magnetic properties of multi-walled carbon nanotubes modified with iron  

NASA Astrophysics Data System (ADS)

Magnetic properties of multi-walled carbon nanotubes modified with iron (MWCNT+Fe) are studied in detail in the temperature range 4.2-300 K. Carbon encapsulated Fe nanoparticles were produced by chemical vapor deposition. Low-temperature SQUID magnetization measurements are supplemented by structural studies employing thermogravimetric (TG) analysis, transmission electron microscopy (TEM), x-ray diffraction spectroscopy (XRD), and scanning electron microscopy (SEM). The magnetic susceptibility of MWCNT+Fe was also studied above room temperature to provide a complete picture of its magnetic phase transitions.

Grechnev, G. E.; Desnenko, V. A.; Fedorchenko, A. V.; Panfilov, A. S.; Kolesnichenko, Yu. A.; Matzui, L. Yu.; Grybova, M. I.; Prylutskyy, Yu. I.; Ritter, U.; Scharff, P.

2010-12-01

50

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

PubMed

A new method for the self-assembly of a carbon nanotube (CNT) using magnetic capturing and fluidic alignment has been developed and characterized in this work. In this new method, the residual iron (Fe) catalyst positioned at one end of the CNT was utilized as a self-assembly driver to attract and position the CNT, while the assembled CNT was aligned by the shear force induced from the fluid flow through the assembly channel. The self-assembly procedures were successfully developed and the electrical properties of the assembled multi-walled carbon nanotube (MWNT) and single-walled carbon nanotube (SWNT) were fully characterized. The new assembly method developed in this work shows its feasibility for the precise self-assembly of parallel CNTs for electronic devices and nanobiosensors. PMID:19620765

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

2009-07-21

51

Carbon nanotube arrays  

Microsoft Academic Search

Carbon nanotube arrays were prepared by chemical vapor deposition (CVD) of hydrocarbon gas on various substrates. The effect of substrates on the growth, morphology and structure of carbon nanotubes were investigated. Aligned carbon nanotubes with high density and purity were achieved by CVD on bulk silica substrate. On the film-like substrates, very long carbon nanotubes of length ~2 mm were produced,

S. S. Xie; W. Z. Li; Z. W. Pan; B. H. Chang; L. F. Sun

1999-01-01

52

Carbon nanotube-coated silicated soft magnetic carbonyl iron microspheres and their magnetorheology  

NASA Astrophysics Data System (ADS)

Core-shell structured magnetic microspheres were fabricated by coating the surface of silicated soft magnetic carbonyl iron particles with multi-walled carbon nanotubes using a facile layer-by-layer method involving an alternative sequential adsorption of positive and negative polyelectrolytes. The morphology of the fabricated particles was observed by scanning electron microscopy. The magnetorheological (MR) behavior affected by the non-magnetic coatings was examined using a rotational rheometer under a controlled magnetic field. The flow curves of typical MR characteristics with improved shear stresses were observed under a range of magnetic field strengths.

Liu, Y. D.; Choi, H. J.

2012-04-01

53

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.

Poplawska, Magdalena

2013-01-01

54

Magnetic properties of multi-walled carbon nanotube–epoxy composites  

Microsoft Academic Search

Epoxy matrix composites have been prepared using as filler different weight fractions (0.03–1wt%) of CVD grown multi-walled carbon nanotubes (MWCNTs) containing trapped iron nanoparticles. Magnetic characterization performed at room temperature with magnetic field between ?19 and 19kG shows that the nanocomposites are weakly ferromagnetic at room temperature. An abrupt variation in the dependence of both the coercivity field, BC, and

D. Zilli; C. Chiliotte; M. M. Escobar; V. Bekeris; G. R. Rubiolo; A. L. Cukierman; S. Goyanes

2005-01-01

55

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

Microsoft Academic Search

We demonstrate a highly sensitive electrochemical immunosensor based on the combined use of substrate recycling and carbon nanotubes (CNTs) coated with tyrosinase (TYR) and magnetic nanoparticles (MNP). Both TYR and MNP were immobilized on the surface of CNTs by covalent attachment, followed by additional cross-linking via glutaraldehyde treatment to construct multi-layered cross-linked TYR-MNP aggregates (M-EC-CNT). Magnetically capturable, highly active and

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

2011-01-01

56

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

Microsoft Academic Search

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

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

2008-01-01

57

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

SciTech Connect

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

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

2008-08-04

58

Mechanical Measurement of Magnetization Reversal in a Single Iron Filled Carbon Nanotube  

NASA Astrophysics Data System (ADS)

The hysteresis loop and switching behavior of an individual Fe-filled carbon nanotube (FeCNT) has been measured at low temperatures using cantilever magnetometry. From the magnetometry data, we are able to extract the total moment of the nanotube and the effective anisotropy field arising from the extreme aspect ratio of the nanotube (length ˜13 ?m, diameter ˜ 25 nm). We find the magnetization reversal in the FeCNT occurs at a well defined switching field Hsw and in a single step. These switching fields (Hsw = 2245 G at 4.2 K) are characterized by a narrow distribution (?sw<= 1 G) and their measured temperature dependence is consistent with a thermally activated process of magnetization reversal. This work was supported by the NSF Materials World Network grant DMR-0807093 and a NSF I2CAM Grant DMR-0645461. P.B. acknowledges support of the ICAM Branches Cost Sharing Fund for a postdoctoral fellowship.

Banerjee, Palash; Herman, M.; Fong, K. C.; Pelekhov, D. V.; Obukhov, Yu.; Hammel, P. Chris; Wolny, F.; Weissker, U.; Mühl, T.; Leonhardt, A.; Büchner, Bernd

2009-03-01

59

Tuning the electronic states of carbon nanotube based devices under magnetic field  

NASA Astrophysics Data System (ADS)

Carbon nanotubes have already demonstrated their wide potential in nanoelectronics and optoelectronics. In our study, we demonstrate that an applied magnetic field, along with a control of the electrostatic doping, drastically modifies the electronic band structure of a carbon nanotube based transistor. Several examples will be addressed in this presentation. In a parallel configuration (B parallel to the tube axis), a quantum flux threading the tube induces a giant Aharonov-Bohm conductance modulation mediated by Schottky barriers which profile is magnetic field dependent. In the perpendicular configuration, the applied magnetic field breaks the revolution symmetry along the circumference and non conventional Landau states are expected in the high field regime. By playing with a carbon nanotube based electronic Fabry-Perot resonator, we bring evidence that the electronic transmission of the device can be modified by a transverse magnetic field. The field dependence of the resonant states of the cavity reveals the onset of the first landau state at zero energy. These experiments also enlighten the outstanding efficiency of magneto-conductance experiments to probe the electronic properties of carbon based nano-materials.

Nanot, Sebastien; Raquet, Bertrand; Escoffier, Walter; Broto, Jean-Marc; Avriller, Remi; Roche, Stephan

2009-03-01

60

Functionalization of carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes have unique properties that make them attractive for different engineering applications. However, because of their chemical inertness, carbon nanotubes have to be functionalized in order to acquire additional physico-chemical properties. Large multiwalled carbon nanotubes are different from fullerenes and singlewalled nanotubes because the stresses in their walls are almost relaxed while most chemical methods for fullerene functionalization exploit

Guzeliya Korneva

2008-01-01

61

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.

2011-06-03

62

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

SciTech Connect

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

Fujita, Takeshi; Hayashi, Yasuhiko; Tokunaga, Tomoharu; Yamamoto, Kazuo [International Frontier Center for Advanced Materials, Institute for Materials Research, Tohoku University, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Department of Environmental Technology and Urban Planning, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555 (Japan); Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka 812-8581 (Japan); Japan Society for the Promotion of Science, Center for Solid State Science, Arizona State University, Tempe, Arizona 85287-1704 (United States)

2006-06-12

63

Removal of cationic dyes from aqueous solution using magnetic multi-wall carbon nanotube nanocomposite as adsorbent  

Microsoft Academic Search

A magnetic multi-wall carbon nanotube (MMWCNT) nanocomposite was synthesized and was used as an adsorbent for removal of cationic dyes from aqueous solutions. The MMWCNT nanocomposite was composed of commercial multi-wall carbon nanotubes and iron oxide nanoparticles. The properties of this magnetic adsorbent were characterized by scanning electron microscopy, X-ray diffraction and BET surface area measurements. Adsorption characteristics of the

Ji-Lai Gong; Bin Wang; Guang-Ming Zeng; Chun-Ping Yang; Cheng-Gang Niu; Qiu-Ya Niu; Wen-Jin Zhou; Yi Liang

2009-01-01

64

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

Microsoft Academic Search

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

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

2005-01-01

65

Magneto-Coulomb Effect in Carbon Nanotube Quantum Dots Filled with Magnetic Nanoparticles  

Microsoft Academic Search

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

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

2011-01-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

67

Exploring the magnetically induced field effect in carbon nanotube-based devices  

NASA Astrophysics Data System (ADS)

We report on the high magnetic field study of transport properties of gated small diameter (quasi)-metallic single wall carbon nanotubes (CNTs). We show that initially metallic CNT devices operate as CNT field-effect transistors under strong magnetic fields. This effect results from the Aharonov Bohm phenomena at the origin of a band gap opening in metallic nanotubes. Strong exponential magnetoresistance observed up to room temperature is the ultimate consequence of the linear increase of the band gap with a magnetic field. Finally, we show that intrinsic characteristics of a quasi-metallic CNT, such as the helical symmetry, as well as the parameters of the Schottky barriers formed at the contacts, can be deduced from temperature-dependent magnetoconductance measurements.

Fedorov, G.; Tselev, A.; Jimenez, D.; Latil, S.; Kalugin, N. G.; Barbara, P.; Smirnov, D.; Roche, S.

2008-03-01

68

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

69

Synthesis of a hybrid material consisting of magnetic iron-oxide nanoparticles and carbon nanotubes as a gas adsorbent  

Microsoft Academic Search

A hybrid material, consisting of magnetic iron-oxide nanoparticles (MINPs) and carbon nanotubes (CNTs), abbreviated MCNT, is synthesized by electrostatic interaction between MINPs and the surface of microwave-assisted acidified multi-walled carbon nanotubes (MWCNTs). MINPs uniformly formed and dispersed on the surface of the acidified MWCNTs which were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, vibrating sample magnetometry, and Raman spectroscopy.

Pei-Ling Lee; Yu-Kai Chiu; Yuh-Chang Sun; Yong-Chien Ling

2010-01-01

70

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

PubMed Central

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

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

2011-01-01

71

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

72

Electrowetting in Carbon Nanotubes  

Microsoft Academic Search

We demonstrate reversible wetting and filling of open single-wall carbon nanotubes with mercury by means of electrocapillary pressure originating from the application of a potential across an individual nanotube in contact with a mercury drop. Wetting improves the conductance in both metallic and semiconducting nanotube probes by decreasing contact resistance and forming a mercury nanowire inside the nanotube. Molecular dynamics

J. Y. Chen; A. Kutana; C. P. Collier; K. P. Giapis

2005-01-01

73

High coercivity magnetic multi-wall carbon nanotubes for low-dimensional high-density magnetic recording media  

Microsoft Academic Search

Fe-embedded multi-wall carbon nanotubes (MWCNTs) were fabricated using Fe-catalyst by the chemical deposition method. Microscopic characterizations showed that the well-aligned MWCNTs were ?80mm in length, with outer diameter of 20–50nm and inner diameter of 10–20nm. Magnetic properties were characterized in temperatures of 5K and 305K, which revealed that the MWCNTs exhibited high coercivity of 2600Oe at 5K and 732Oe at

S. C. Ray; S. Bhattacharyya; S. L. Wu; D. C. Ling; W. F. Pong; M. Giorcelli; S. Bianco; A. Tagliaferro

2010-01-01

74

Effects of Ion Bombardment on Carbon Nanotube Formation in Strongly Magnetized Glow-Discharge Plasmas  

NASA Astrophysics Data System (ADS)

The effects of ion bombardment on the formation of multi-walled carbon nanotubes (MWNTs) are investigated by controlling radio-frequency (rf) glow-discharge plasmas in strong magnetic fields. When a magnetic field is weak (0.03 T), the MWNTs growing directly on an rf electrode are deformed by the bombardment of the high-energy ions generated by a large sheath electric field in front of the rf electrode. On the other hand, when a strong magnetic field (2 T) is applied, the MWNTs are observed to be well aligned and not to be deformed even under the condition that the rf electrode is negatively biased. These results can be explained by the fact that the ion bombardment energy is reduced despite the existence of the large sheath electric field, which is caused by the magnetization of the ions in the strong magnetic field.

Kaneko, Toshiro; Matsuoka, Hiroki; Hatakeyama, Rikizo; Tohji, Kazuyuki

2005-04-01

75

Magnetic effects on nonlinear mechanical properties of a suspended carbon nanotube  

NASA Astrophysics Data System (ADS)

We propose a microscopic model for a nanoelectromechanical system made by a radio-frequency driven suspended carbon nanotube (CNT) in the presence of an external magnetic field perpendicular to the current. As a main result, we show that, when the device is driven far from equilibrium, one can tune the CNT mechanical properties by varying the external magnetic field. Indeed, the magnetic field affects the CNT bending mode dynamics inducing an enhanced damping as well as a noise term due to the electronic phase fluctuations. The quality factor, as observed experimentally, exhibits a quadratic dependence on external magnetic field strength. Finally, CNT resonance frequencies as a function of gate voltage acquire, increasing the magnetic field strength, a peculiar dip-peak structure that should be experimentally observed.

Nocera, A.; Perroni, C. A.; Ramaglia, V. Marigliano; Cantele, G.; Cataudella, V.

2013-04-01

76

Anchoring of rare-earth-based single-molecule magnets on single-walled carbon nanotubes.  

PubMed

A new heteroleptic bis(phthalocyaninato) terbium(III) complex 1, bearing a pyrenyl group, exhibits temperature and frequency dependence of ac magnetic susceptibility, typical of single-molecule magnets. The complex was successfully attached to single-walled carbon nanotubes (SWNTs) using pi-pi interactions, yielding a 1-SWNT conjugate. The supramolecular grafting of 1 to SWNTs was proven qualitatively and quantitatively by high-resolution transmission electron microscopy, emission spectroscopy, and atomic force spectroscopy. Giving a clear magnetic fingerprint, the anisotropy energy barrier and the magnetic relaxation time of the 1-SWNT conjugate are both increased in comparison with the pure crystalline compound 1, likely due to the suppression of intermolecular interactions. The obtained results propose the 1-SWNT conjugate as a promising constituent unit in magnetic single-molecule measurements using molecular spintronics devices. PMID:19799421

Kyatskaya, Svetlana; Mascarós, José Ramón Galán; Bogani, Lapo; Hennrich, Frank; Kappes, Manfred; Wernsdorfer, Wolfgang; Ruben, Mario

2009-10-28

77

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

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

78

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

79

Carbon Nanotube Filter.  

National Technical Information Service (NTIS)

Monolithic, macroscopic, nanoporous nanotube filters are fabricated having radially aligned carbon nanotube walls. The freestanding filters have diameters and lengths up to several centimeters. A single-step filtering process was demonstrated in two impor...

A. Srivastava O. N. Srivastava P. M. Ajayan R. Vajtal S. Talapatra

2005-01-01

80

Collective electronic excitations in magnetically aligned single wall carbon nanotubes studied by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Samples with magnetically aligned single wall carbon nanotubes (SWNT) have been studied by Raman spectroscopy in the low frequency spectral range: 10 - 700 cm-1. A novel Raman-active electronic collective excitation has been observed. At room temperature the excitation band is at about 30 cm-1. The band dramatically strengthens and softens down to about 15 cm-1 with sample cooling below 50 K. The polarization dependence of the Raman spectra was analyzed for laser excitation energies in resonance with electronic transitions and it was compared to that in the case of non-resonant excitation. Strong anisotropy of Raman response function of the SWNT has been observed: for polarization parallel to the direction of the nanotubes the electronic excitation band is about 4 times stronger than that for the perpendicular direction. The origin of the 1-D electronic excitation in metallic SWNT will be discussed.

Blumberg, G.; Gozar, A.; Dennis, B. S.; Sirenko, A. A.; Eklund, P. C.; Walters, D. A.; Casavant, M. J.; Schmidt, J.; Smalley, R. E.

2001-03-01

81

Dual Modality Photothermal Optical Coherence Tomography and Magnetic Resonance Imaging of Carbon Nanotubes  

PubMed Central

We demonstrate polyethylene glycol coated single-walled carbon nanotubes (CNTs) as contrast agents for both photothermal optical coherence tomography (OCT) and magnetic resonance imaging. Photothermal OCT was accomplished with a spectral domain OCT system with an amplitude modulated 750 nm pump beam using 10 mW of power, and T2 MR imaging was achieved with a 4.7 T animal system. Photothermal OCT and T2 MR imaging achieved sensitivities of nM concentrations to CNTs dispersed in amine terminated polyethylene glycol, thus establishing the potential for dual-modality molecular imaging with CNTs.

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

2012-01-01

82

Synthesis and magnetic properties of aligned carbon nanotubes by microwave-assisted pyrolysis of acetylene  

NASA Astrophysics Data System (ADS)

Aligned carbon nanotubes with high quality were synthesized at low temperature by microwave-assisted pyrolysis of acetylene in nitrogen atmosphere. The morphology and structure of the products were characterized by field-emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The results indicated that the ACNTs with high crystallinity are densely packed, and some Fe3C nanoparticles are encapsulated in all parts of carbon tubes. In addition, the effect of the reaction temperature on the morphologies of the CNTs was also studied in detail. Magnetic measurements showed that the Fe3C-filled ACNTs display ferromagnetic properties at room temperature, and can be easily manipulated by an external magnetic field.

Fu, Dongju; Ma, Qing; Zeng, Xierong; Chen, Jianjun; Zhang, Weili; Li, Dongshuang

2013-12-01

83

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

84

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

85

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

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNT) provide a well-defined environment for the study of confined water, whose behavior can differ markedly from bulk water. The application of nuclear magnetic resonance (NMR) to probe the local water structure and dynamics in these cases is hindered by ambiguities in the interpretation of the NMR spectra. We employ linear response theory to evaluate the ^1H chemical shieldings of liquid water in semiconducting CNTs, where the electronic structure is derived from density functional theory with periodic boundary conditions. The shieldings are sampled from trajectories generated via first-principles molecular dynamics simulations at ambient conditions, for water in CNTs with diameters d=11 åand 14.9 å@. We find a large (˜-23 ppm) upfield shift relative to bulk liquid water, which is a consequence of strongly anisotropic magnetic fields induced in the CNT by the applied magnetic field.

Huang, Patrick; Schwegler, Eric; Galli, Giulia

2009-03-01

86

Fabrication of a novel glucose biosensor based on Pt nanoparticles-decorated iron oxide-multiwall carbon nanotubes magnetic composite  

Microsoft Academic Search

A sensitive and selective amperometric glucose biosensor was obtained by using the electrodeposition of Pt nanoparticles on iron oxide-multiwall carbon nanotubes\\/chitosan (FeyOx-MWCNTs\\/CS) magnetic composite modified glassy carbon electrode (GCE) followed by the adsorption of glucose oxidase (GOx) at the surface of the electrode. FeyOx-MWCNTs magnetic composite was characterized by transmission electron microscopy (TEM). The modified process and the electrochemical characteristics

Jingjing Li; Ruo Yuan; Yaqin Chai; Xin Che

2010-01-01

87

Carbon Nanotube Biosensors  

Microsoft Academic Search

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

Pingang He; Liming Dai

88

Fabrication of Carbon Nanotubes  

Microsoft Academic Search

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

Christopher T. Kingston; Benoit Simard

2003-01-01

89

Forced Mechanical Oscillations of a Carbon Nanotube  

Microsoft Academic Search

Single-walled carbon nanotubes that are suspended over a trench between two electrodes can be made to oscillate by means of a Lorentz force, by placing the nanotube in a perpendicular magnetic field and applying a high-frequency alternating current. Modeled as a classical, clamped beam, a 100 nm nanotube has a fundamental mechanical resonance frequency of about 10 GHz. Oscillations near

Myles Steiner; Thomas Tombler; Chongwu Zhou; Hongjie Dai; Aharon Kapitulnik

2000-01-01

90

CVD synthesis of coal-gas-derived carbon nanotubes and nanocapsules containing magnetic iron carbide and oxide  

Microsoft Academic Search

Iron carbide–oxide filled carbon nanotubes and nanocapsules (CNCs) are separately synthesized by catalytic chemical vapor deposition of coal gas at 950°C with ferrocene as catalyst. The products are examined using transmission electron microscopy and XRD techniques, showing that nanosized iron carbide–oxide particles are encapsulated by well ordered carbon layers. Magnetic moment measurement reveals that these carbon encapsulated iron carbide–oxides exhibit

Jieshan Qiu; Qixiu Li; Zhiyu Wang; Yufeng Sun; Hongzhe Zhang

2006-01-01

91

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

92

Chromium removal by combining the magnetic properties of iron oxide with adsorption properties of carbon nanotubes.  

PubMed

The adsorption features of multiwall carbon nanotubes (MWCNTs) with the magnetic properties of iron oxides have been combined in a composite to produce a magnetic adsorbent. Composites of MWCNT/nano-iron oxide were prepared, and were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FTIR). XRD suggests that the magnetic phase formed is maghemite and/or magnetite. FESEM image shows nano-iron oxides attached to a network of MWCNTs. The adsorption capability of the composites was tested in batch and fixed bed modes. The composites have demonstrated a superior adsorption capability to that of activated carbon. The results also show that the adsorptions of Cr(III) on the composites is strongly dependent on contact time, agitation speed and pH, in the batch mode; and on flow rate and the bed thickness in the fixed bed mode. Along with the high surface area of the MWCNTs, the advantage of the magnetic composite is that it can be used as adsorbent for contaminants in water and can be subsequently controlled and removed from the medium by a simple magnetic process. PMID:21303713

Gupta, V K; Agarwal, Shilpi; Saleh, Tawfik A

2011-01-22

93

Vibration response of double-walled carbon nanotubes subjected to an externally applied longitudinal magnetic field: A nonlocal elasticity approach  

NASA Astrophysics Data System (ADS)

The magnetic properties of carbon nanotubes and their mechanical behaviour in a magnetic field have attracted considerable attention among the scientific and engineering communities. This paper reports an analytical approach to study the effect of a longitudinal magnetic field on the transverse vibration of a magnetically sensitive double-walled carbon nanotube (DWCNT). The study is based on nonlocal elasticity theory. Equivalent analytical nonlocal double-beam theory is utilised. Governing equations for nonlocal transverse vibration of the DWCNT under a longitudinal magnetic field are derived considering the Lorentz magnetic force obtained from Maxwell's relation. Numerical results from the model show that the longitudinal magnetic field increases the natural frequencies of the DWCNT. Both synchronous and asynchronous vibration phases of the tubes are studied in detail. Synchronous vibration phases of DWCNT are more affected by nonlocal effects than asynchronous vibration phases. The effects of a longitudinal magnetic field on higher natural frequencies are also presented. Vibration response of DWCNT with outer-wall stationary and single-walled carbon nanotube under the effect of longitudinal magnetic field are also discussed in the paper.

Murmu, T.; McCarthy, M. A.; Adhikari, S.

2012-11-01

94

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

NASA Astrophysics Data System (ADS)

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

Tooski, S. B.

2009-10-01

95

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

SciTech Connect

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

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

2009-10-15

96

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

97

Carbon nanotube polymer composites  

Microsoft Academic Search

The state of research into carbon nanotube\\/polymer–matrix composites for mechanical reinforcement is critically reviewed with emphasis on recent advances in CNT composite toughness. Particular interest is also given to interfacial bonding of carbon nanotubes to polymer matrices as it applies to stress transfer from the matrix to the CNT. Potential topics of oncoming focus are highlighted.

R. Andrews; M. C. Weisenberger

2004-01-01

98

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

99

Carbon Nanotube templated structures  

Microsoft Academic Search

Carbon nano tubes are of great interest to science due to their strong mechanical and exotic electrical properties. Nano tubes have potential application in transistors, micro electrical mechanical devices (MEMS), and structural materials. We have been using nanotube forests as a template to fabricate larger scale structures. The nanotube template is infiltrated with another material (like silicon or carbon). This

Ricky Wyman; Robert Davis; Richard Vanfleet; Jun Song

2009-01-01

100

On the synthesis and magnetic properties of multiwall carbon nanotube-superparamagnetic iron oxide nanoparticle nanocomposites  

Microsoft Academic Search

Multiwall carbon nanotubes (MWCNTs) possessing an average inner diameter of 150 nm were synthesized by template assisted chemical vapor deposition over an alumina template. Aqueous ferrofluid based on superparamagnetic iron oxide nanoparticles (SPIONs) was prepared by a controlled co-precipitation technique, and this ferrofluid was used to fill the MWCNTs by nanocapillarity. The filling of nanotubes with iron oxide nanoparticles was

T. N. Narayanan; A. P. Reena Mary; M. M. Shaijumon; Lijie Ci; P. M. Ajayan; M. R. Anantharaman

2009-01-01

101

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

NASA Astrophysics Data System (ADS)

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

Louie, Richard Nam

2002-12-01

102

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

PubMed

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

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

2012-11-28

103

Strong spin-phonon coupling between a single-molecule magnet and a carbon nanotube nanoelectromechanical system  

NASA Astrophysics Data System (ADS)

Magnetic relaxation processes were first discussed for a crystal of paramagnetic transition ions. It was suggested that mechanical vibrations of the crystal lattice (phonons) modulate the crystal electric field of the magnetic ion, thus inducing a `direct' relaxation between two different spin states. Direct relaxation has also been predicted for single-molecule magnets with a large spin and a high magnetic anisotropy and was first demonstrated in a Mn12 acetate crystal. The spin-lattice relaxation time for such a direct transition is limited by the phonon density of states at the spin resonance. In a three-dimensional system, such as a single-molecule magnet crystal, the phonon energy spectrum is continuous, but in a one-dimensional system, like a suspended carbon nanotube, the spectrum is discrete and can be engineered to an extremely low density of states. An individual single-molecule magnet, coupled to a suspended carbon nanotube, should therefore exhibit extremely long relaxation times and the system's reduced size should result in a strong spin-phonon coupling. Here, we provide the first experimental evidence for a strong spin-phonon coupling between a single molecule spin and a carbon nanotube resonator, ultimately enabling coherent spin manipulation and quantum entanglement.

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

2013-03-01

104

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

NASA Astrophysics Data System (ADS)

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

Zhao, Hong-Kang; Wang, Jian

2004-03-01

105

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

PubMed

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

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

2013-10-10

106

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

NASA Astrophysics Data System (ADS)

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

Cobden, David

2006-03-01

107

The effects of a static magnetic field on the microwave absorption of hydrogen plasma in carbon nanotubes: a numerical study  

NASA Astrophysics Data System (ADS)

We theoretically investigate the microwave absorption properties of hydrogen plasma in iron-catalyzed high-pressure disproportionation-grown carbon nanotubes under an external static magnetic field in the frequency range 0.3 GHz to 30 GHz, using the Maxwell equations in conjunction with a general expression for the effective complex permittivity of magnetized plasma known as the Appleton—Hartree formula. The effects of the external static magnetic field intensity and the incident microwave propagation direction on the microwave absorption of hydrogen plasma in CNTs are studied in detail. The numerical results indicate that the microwave absorption properties of hydrogen plasma in iron-catalyzed high-pressure disproportionation-grown carbon nanotubes can be obviously improved when the external static magnetic field is applied to the material. It is found that the specified frequency microwave can be strongly absorbed by the hydrogen plasma in iron-catalyzed high-pressure disproportionation-grown carbon nanotubes over a wide range of incidence angles by adjusting the external magnetic field intensity and the parameters of the hydrogen plasma.

Peng, Zhi-Hua; Gong, Xue-Yu; Peng, Yan-Feng; Guo, Yan-Chun; Ning, Yan-Tao

2012-07-01

108

Carbon nanotube arrays  

NASA Astrophysics Data System (ADS)

Carbon nanotube arrays were prepared by chemical vapor deposition (CVD) of hydrocarbon gas on various substrates. The effect of substrates on the growth, morphology and structure of carbon nanotubes were investigated. Aligned carbon nanotubes with high density and purity were achieved by CVD on bulk silica substrate. On the film-like substrates, very long carbon nanotubes of length 2 mm were produced, which is an order of magnitude longer (1 mm vs. 100 ?m) than that described in most previous reports. High-resolution transmission electron microscopy (HRTEM) investigation illustrates that these carbon nanotubes are well graphitized and very pure. The tubes are typically consist of several to tens of concentric shells of carbon sheets with spacing about 0.34 nm. Micro-Raman spectroscopy has been carried out to detect the microstructures of CNT. The observed ratio of the integrated intensity of D and G band was found different from that of carbon nanotubes produced by arc-discharge method and pyrolytic graphite (PG). The resonance properties and higher order Raman bands are also different from other forms of carbon. With the help of the results of SEM and HRTEM the origination of the broader band structure were discussed.

Xie, S. S.; Li, W. Z.; Pan, Z. W.; Chang, B. H.; Sun, L. F.

109

Filling carbon nanotubes  

NASA Astrophysics Data System (ADS)

Filling hollow carbon nanotubes with chosen materials opens new possibilities of generating nearly one-dimensional nanostrutures. One simple approach to fill nanotubes is to use capillarity forces. Here, we have studied the wetting and capillarity by metal salts. First, nanotubes were opened by oxidation in air; subsequently, nanotubes were immersed in molten salts. We have observed a size-dependence filling indicating a lowering of the cavity-salt interface energy with decreasing diameter. By expressing the wetting conditions as a function of polarizabilities, it is possible to predict the threshold diameter for capillary filling of different materials.

Ugarte, D.; Stöckli, T.; Bonard, J. M.; Châtelain, A.; de Heer, W. A.

110

Molecular Quantum Spintronics: Supramolecular Spin Valves Based on Single-Molecule Magnets and Carbon Nanotubes  

PubMed Central

We built new hybrid devices consisting of chemical vapor deposition (CVD) grown carbon nanotube (CNT) transistors, decorated with TbPc2 (Pc = phthalocyanine) rare-earth based single-molecule magnets (SMMs). The drafting was achieved by tailoring supramolecular ?-? interactions between CNTs and SMMs. The magnetoresistance hysteresis loop measurements revealed steep steps, which we can relate to the magnetization reversal of individual SMMs. Indeed, we established that the electronic transport properties of these devices depend strongly on the relative magnetization orientations of the grafted SMMs. The SMMs are playing the role of localized spin polarizer and analyzer on the CNT electronic conducting channel. As a result, we measured magneto-resistance ratios up to several hundred percent. We used this spin valve effect to confirm the strong uniaxial anisotropy and the superparamagnetic blocking temperature (TB ~ 1 K) of isolated TbPc2 SMMs. For the first time, the strength of exchange interaction between the different SMMs of the molecular spin valve geometry could be determined. Our results introduce a new design for operable molecular spintronic devices using the quantum effects of individual SMMs.

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

2011-01-01

111

In vivo imaging of carbon nanotube biodistribution using magnetic resonance imaging.  

PubMed

As novel engineered nanoparticles such as carbon nanotubes (CNTs) are extensively used in nanotechnology due to their superior properties, it becomes critical to fully understand their biodistribution and effect when accidently inhaled. A noninvasive follow-up study would be beneficial to evaluate the biodistribution and effect of nanotube deposition after exposure directly in vivo. Combined helium-3 and proton magnetic resonance resonance (MRI) were used in a rat model to evaluate the biodistribution and biological impact of raw single-wall CNTs (raw-SWCNTs) and superpurified SWCNTs (SP-SWCNTs). The susceptibility effects induced by metal impurity in the intrapulmonary instilled raw-SWCNT samples were large enough to induce a significant drop in magnetic field homogeneity detected in 3He MR image acquired under spontaneous breathing conditions using a multiecho radial sequence. No MRI susceptibility variation was observed with SP-SWCNT exposition even though histological analysis confirmed their presence in instilled lungs. Proton MRI allowed detection of intravenously injected raw-SWCNTs in spleen and kidneys using gradient echo sequence sensitive to changes of relaxation time values. No signal modifications were observed in the SP-SWCNT injected group. In instilled groups, the contrast-to-noise ratio in liver, spleen, and kidneys stayed unchanged and were comparable to values obtained in the control group. Histological analysis confirms the absence of SWCNTs in systemic organs when SWCNTs were intrapulmonary instilled. In conclusion, the presence of SWCNTs with associated metal impurities can be detected in vivo by noninvasive MR techniques. Hyperpolarized 3He can be used for the investigation of CNT pulmonary biodistribution while standard proton MR can be performed for systemic investigation following injection of CNT solution. PMID:19199447

Al Faraj, Achraf; Cieslar, Katarzyna; Lacroix, Ghislaine; Gaillard, Sophie; Canet-Soulas, Emmanuelle; Crémillieux, Yannick

2009-03-01

112

Carbon Nanotube Solar Cells  

PubMed Central

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

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

2012-01-01

113

Magnetic switching of ferromagnetic nanotubes  

NASA Astrophysics Data System (ADS)

The magnetic switching of ferromagnetic nanotubes as function of geometrical parameters has been investigated. The modes of magnetization reversal are observed to depend on the geometry of the nanotubes. Time dependent magnetization properties reveal that the nanotubes have strong magnetic viscosity effects. The values of magnetic viscosity coefficient (S) for different applied fields are high near the coercive field.

Sharif, R.; Shamaila, S.; Ma, M.; Yao, L. D.; Yu, R. C.; Han, X. F.; Khaleeq-Ur-Rahman, M.

2008-01-01

114

Removal of cationic dyes from aqueous solution using magnetic multi-wall carbon nanotube nanocomposite as adsorbent.  

PubMed

A magnetic multi-wall carbon nanotube (MMWCNT) nanocomposite was synthesized and was used as an adsorbent for removal of cationic dyes from aqueous solutions. The MMWCNT nanocomposite was composed of commercial multi-wall carbon nanotubes and iron oxide nanoparticles. The properties of this magnetic adsorbent were characterized by scanning electron microscopy, X-ray diffraction and BET surface area measurements. Adsorption characteristics of the MMWCNT nanocomposite adsorbent were examined using methylene blue, neutral red and brilliant cresyl blue as adsorbates. Experiments were carried out to investigate adsorption kinetics, adsorption capacity of the adsorbent and the effect of adsorption dosage and solution pH values on the removal of cationic dyes. Kinetic data were well fitted by a pseudo second-order model. Freundlich model was used to study the adsorption isotherms. The prepared MMWCNT adsorbent displayed the main advantage of separation convenience compared to the present adsorption treatment. PMID:18977077

Gong, Ji-Lai; Wang, Bin; Zeng, Guang-Ming; Yang, Chun-Ping; Niu, Cheng-Gang; Niu, Qiu-Ya; Zhou, Wen-Jin; Liang, Yi

2008-09-26

115

Carbon nanotubes in interconnect applications  

Microsoft Academic Search

Carbon nanotubes with their outstanding electrical and mechanical properties are suggested as an interconnect material of the future. In this paper we will introduce nanotubes, compare their electrical properties with equivalent metal wires made of gold and describe our progress in process integration. Multi-walled carbon nanotubes are grown on 6-inch wafers in a batch process. The resulting nanotubes are evaluated

Franz Kreupl; Andrew P. Graham; G. S Duesberg; W Steinhögl; M Liebau; Eugen Unger; W Hönlein

2002-01-01

116

Nano Sized Magnetic Particles with Diameters Less than 1 nm Encapsulated in Single-Walled Carbon Nanotubes  

Microsoft Academic Search

The synthesis of magnetic nano sized Fe particle-encapsulated single-walled carbon nanotubes (SWNTs) has been realized for the first time by a two-step method. In this method, ferrocene is selected as a starting material and used in filling SWNTs. Then, the as-synthesized ferrocene-filled SWNTs are decomposed to release Fe atoms inside the SWNTs. Both ferrocene-filled SWNT and Fe-filled SWNT samples are

Yongfeng Li; Rikizo Hatakeyama; Toshiro Kaneko; Takeru Okada

2006-01-01

117

Far- and mid-infrared anisotropy of magnetically aligned single-wall carbon nanotubes studied with synchrotron radiation  

NASA Astrophysics Data System (ADS)

We performed polarized infrared reflectivity measurements on magnetically oriented carbon nanotubes using conventional light sources as well as synchrotron radiation. A strong anisotropy in the far-infrared spectral range was found, indicating preferred orientation of metallic tubes. Much less effect is seen in the spectral region typical of semiconducting tubes. We propose an explanation based on preferred orientation of metallic tubes, polarization-dependent dipole selection rules, and possible doping effects in these materials.

Kamarás, K.; Thirunavukkuarasu, K.; Kuntscher, C. A.; Dressel, M.; Simon, F.; Kuzmany, H.; Walters, D. A.; Moss, D. A.

2006-09-01

118

Magnetically aligned single wall carbon nanotube films: Preferred orientation and anisotropic transport properties  

NASA Astrophysics Data System (ADS)

Thick films of single wall carbon nanotubes (SWNT) exhibiting in-plane preferred orientation have been produced by filter deposition from suspension in strong magnetic fields. We characterize the field-induced alignment with x-ray fiber diagrams and polarized Raman scattering, using a model which includes a completely unaligned fraction. We correlate the texture parameters with resistivity and thermal conductivity measured parallel and perpendicular to the alignment direction. Results obtained with 7 and 26 T fields are compared. We find no significant field dependence of the distribution width, while the aligned fraction is slightly greater at the higher field. Anisotropy in both transport properties is modest, with ratios in the range 5-9, consistent with the measured texture parameters assuming a simple model of rigid rod conductors. We suggest that further enhancements in anisotropic properties will require optimizing the filter deposition process rather than larger magnetic fields. We show that both x-ray and Raman data are required for a complete texture analysis of oriented SWNT materials.

Fischer, J. E.; Zhou, W.; Vavro, J.; Llaguno, M. C.; Guthy, C.; Haggenmueller, R.; Casavant, M. J.; Walters, D. E.; Smalley, R. E.

2003-02-01

119

Carbon Nanotube Material Quality Assessment.  

National Technical Information Service (NTIS)

The nanomaterial activities at NASA Johnson Space Center focus on carbon nanotube production, characterization and their applications for aerospace systems. Single wall carbon nanotubes are produced by arc and laser methods. Characterization of the nanotu...

E. Sosa L. Yowell O. Gorelik P. Niolaev S. Arepalli

2006-01-01

120

Preparation and magnetic properties of iron oxide and carbide nanoparticles in carbon nanotube matrix  

Microsoft Academic Search

The present work describes a procedure for the preparation of iron oxide and carbide nanoparticles in carbon nanotube (CNT) matrix using the wet impregnation method and subsequent heat treatment in different atmosphere. In this way, two specific composites were produced with magnetite and cementite phase particles dispersed in CNTs, respectively, and cementite particles were encapsulated in graphene shells. As-prepared nanoparticles

J. P. Cheng; X. B. Zhang; G. F. Yi; Y. Ye; M. S. Xia

2008-01-01

121

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

122

Electrical and thermal transport properties of magnetically aligned single wall carbon nanotube films  

Microsoft Academic Search

Bulk samples of parallel single-walled nanotubes ~SWNTs! would constitute a fascinating new material, with highly anisotropic electrical and thermal transport properties. In this letter we report quantitative measurements of the an- isotropic electrical and thermal transport properties of aligned thin films of SWNT ropes deposited from suspension in a high magnetic field. 1 The aligned samples show high electrical (

J. Hone; M. C. Llaguno; N. M. Nemes; A. T. Johnson; J. E. Fischera; D. A. Walters; M. J. Casavant; J. Schmidt; R. E. Smalley

2000-01-01

123

Magnetic carbon nanotube labelling for haematopoietic stem/progenitor cell tracking  

NASA Astrophysics Data System (ADS)

Haematopoietic stem and progenitor cell (HSPC) research has significantly contributed to the understanding and harnessing of haematopoiesis for regenerative medicine. However, the methodology for real-time tracking HSPC in vivo is still lacking, which seriously restricts the progress of research. Recently, magnetic carbon nanotubes (mCNT) have generated great excitement because they have been successfully used as vehicles to deliver a lot of biomolecules into various cells. There is, however, no report about mCNT being used for tracking HSPC. In this paper, we investigated the uptake efficiency of fluorescein-isothiocyanate-labelled mCNT (FITC-mCNT) into HSPC and their effect on the cytotoxicity and differentiation of HSPC. We found that cellular uptake of FITC-mCNT was concentration-and time-dependent. The uptake of FITC-mCNT into HSPC reached up to 100% with the highest mean fluorescence (MF). More importantly, efficient FITC-mCNT uptake has no adverse effect on the cell viability, cytotoxicity and differentiation of HSPC as confirmed by colony-forming unit assay (CFU). In conclusion, the results reported here suggest the further tailoring of mCNT for their use in HSPC labelling/tracking in vivo or gene delivery into HSPC.

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

2010-04-01

124

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

125

Carbon Nanotubes in Microelectronic Applications  

Microsoft Academic Search

Carbon nanotubes with their outstanding electrical and mechanical properties are suggested as interconnect material of the future and as switching devices, which could outperform silicon devices. In this paper we will introduce nanotubes, specify the applications, where nanotubes can contribute to the advancement of Moore's law and show our progress of nanotube process integration in a microelectronic compatible way. The

Franz Kreupl; G. S. Duesberg; A. P. Graham; MAIK LIEBAU; EUGEN UNGER; ROBERT SEIDEL; WERNER PAMLER; W. Hoenlein

2004-01-01

126

Hydrogen uptake by carbon nanotubes  

Microsoft Academic Search

Multi-wall carbon nanotubes were synthesised from the catalytic decomposition of CO and CH4 on powder Co\\/La2O3 catalysts. TEM and HR-TEM, XRD, and TGA were used to characterise carbon nanotubes. It was found that by adjusting the composition of the catalysts, the size of the nanotubes was controllable and by annealing, the crystallinity could be improved. The carbon nanotubes produced from

X. B. Wu; P. Chen; J. Lin; K. L. Tan

2000-01-01

127

Chlorination of carbon nanotubes  

NASA Astrophysics Data System (ADS)

We report ab initio density functional theory calculations for chlorinated single-wall carbon nanotubes and investigate the atomic structure, energetics, and electronic structure of the chlorinated nanotubes, as well as the energetics of the desorption reaction. We find that the Cl atoms should be adsorbed in pairs and thus focus on doubly chlorinated nanotubes. Using the terminology of arene substitution patterns, ortho and para configurations are the most stable. The physisorption is preferable to the chemisorption in large-diameter nanotubes. The impurity states appear near the Fermi level EF in the electronic structure and may alter the electronic properties considerably. The bonding character for adsorption outside the nanotube is mainly covalent, but inside it consists of physical bonding. The adsorption of several Cl atoms inside a carbon nanotube leads to the formation of a charged Cl chain. Our calculated desorption barrier of ?1.4 eV per Cl atom pair indicates that the cleansing by chlorination is a less damaging alternative with removable residue.

Erbahar, Dogan; Berber, Savas

2012-02-01

128

Photoinduced oxidation of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Photoinduced phenomena are of general interest for new materials. Recently, photoinduced molecular desorption of oxygen has been reported in carbon nanotubes. Here we present, using thermopower measurements, that carbon nanotubes when exposed simultaneously to UV light and oxygen exhibit photoinduced oxidation of the nanotubes. At least two plausible mechanisms for the experimentally observed photoinduced oxidation are proposed: (i) a lower energy barrier for the adsorption of photo-generated singlet oxygen, or (ii) due to the presence of defects in carbon nanotubes that may facilitate the formation of locally electron-deficient and electron-rich regions on the nanotubes which facilitate the adsorption of oxygen molecules on the nanotubes.

Savage, T.; Bhattacharya, S.; Sadanadan, B.; Gaillard, J.; Tritt, T. M.; Sun, Y.-P.; Wu, Y.; Nayak, S.; Car, R.; Marzari, N.; Ajayan, P. M.; Rao, A. M.

2003-09-01

129

Carbon nanotube intramolecular devices  

NASA Astrophysics Data System (ADS)

By introducing a pentagon and a heptagon into the hexagonal carbon lattice, two nanotube segments with different atomic and electronic structures can be seamlessly fused together to create junctions within a single nanotube molecule. These junctions could form building blocks for nanotube-based molecular electronics. We have performed electrical measurements of nanotubes with such intramolecular junctions. We find that a metal-semiconductor junction behaves as a rectifying diode with nonlinear and strongly asymmetric current-voltage characteristics. In the case of a metal-metal junction, the conductance appears to be strongly suppressed and it displays a power-law dependence on temperature and voltage, consistent with tunneling between the ends of two Luttinger liquids. We will also discuss intramolecular devices created by mechanical deformation. [1] Z. Yao, H. Postma, L. Balents and C. Dekker, Nature 402, 273 (1999).

Yao, Zhen; Postma, Henk; Dekker, Cees

2000-03-01

130

Carbon Nanotube templated structures  

NASA Astrophysics Data System (ADS)

Carbon nano tubes are of great interest to science due to their strong mechanical and exotic electrical properties. Nano tubes have potential application in transistors, micro electrical mechanical devices (MEMS), and structural materials. We have been using nanotube forests as a template to fabricate larger scale structures. The nanotube template is infiltrated with another material (like silicon or carbon). This infiltration can be thin to stabilize the forest and make a porous structure or thick to make a solid structure. Different methods employed at Brigham Young University of patterning, growing, and infiltrating nano tubes are presented on a poster along with applications.

Wyman, Ricky; Davis, Robert; Vanfleet, Richard; Song, Jun

2009-10-01

131

Tungsten disulphide sheathed carbon nanotubes.  

PubMed

An insulated nanotube wire is formed by the binary phase of layered tungsten disulphide and carbon nanotubes (shown in the HRTEM image) generated by the sulphidization of tungsten oxide coated multiwalled carbon nanotubes at 900 °C. Thermogravimetric analysis shows that the tungsten disulphide coat acts as an antioxidant. PMID:23686882

Whitby, R L; Hsu, W K; Boothroyd, C B; Fearon, P K; Kroto, H W; Walton, D R

2001-10-15

132

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

133

Carbon Nanotube Flow Sensors  

Microsoft Academic Search

We report that the flow of a liquid on single-walled carbon nanotube bundles induces a voltage in the sample along the direction of the flow. The voltage that was produced fit a logarithmic velocity dependence over nearly six decades of velocity. The magnitude of the voltage depended sensitively on the ionic conductivity and on the polar nature of the liquid.

Shankar Ghosh; A. K. Sood; N. Kumar

2003-01-01

134

Regularly coiled carbon nanotubes  

Microsoft Academic Search

Regularly coiled carbon nanotubes, their structure, and formation mechanism are puzzling questions. The first models were based on the very regular incorporation of a small fraction (of the order of 10%) of nonhexagonal (n-Hx) rings: (pentagons and heptagons) in a perfect hexagonal (Hx) lattice. It is difficult to understand by which mechanism takes place such a regular incorporation of isolated

László P Biró; Géza I. Márk; Philippe Lambin

2003-01-01

135

Coiled Carbon Nanotubes  

Microsoft Academic Search

Coiled carbon nanotubes (CCNTs) are CNTs with spiral structure. The CCNTs possess unique properties of helix, chirality and nonlinear mechanical behavior. It attracts great interests in the synthesis, growth mechanisms and application developments. The CCNTs is commonly synthesized by catalyst-supported chemical vapor deposition (CVD) and floating catalyst CVD. The selective production of CCNTs has been achieved. Based on the analysis

Jiaqi Huang; Qiang Zhang; Fei Wei

2009-01-01

136

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

137

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

Microsoft Academic Search

In this paper, a facile synthesis process is proposed to prepare multiwalled carbon nanotubes\\/magnetite (MWCNTs\\/Fe3O4) hybrids. The process involves two steps: (1) water-soluble CNTs are synthesized by one-pot modification using potassium persulfate (KPS) as oxidant. (2) Fe3O4 is assembled along the treated CNTs by employing a facile hydrothermal process with the presence of hydrazine hydrate as the mineralizer. The treated

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

2009-01-01

138

Spin Transport in Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

We report on spin transport in carbon nanotubes. First, spin injection in arc-discharge grown multi-walled carbon nanotubes (MWNTs) is achieved by using a ferromagnetic PdNi alloy as contact material. The two contacts, i.e. source and drain, have different shape rendering different magnetic switching fields. Typical two-terminal resistances are in the range of 5-100 kOhm. We find a tunneling magneto resistance (TMR) signal amounting to 2.5-3%. Secondly, we explore the TMR signal as a function of temperature T, source-drain voltage Vsd, and gate voltage Vg. As expected the TMR signal decays with T and Vsd. Remarkably, however, we find a sign change in the spin signal (the TMR signal) as a function of both Vsd and Vg. This work has been done in collaboration with: S. Sahoo and T. Kontos (Univ. of Basel), C. Sürgers (Univ. of Karlsruhe), and L. Forro (EPFL Lausanne).

Schoenenberger, Christian

2005-03-01

139

The biocompatibility of carbon nanotubes  

Microsoft Academic Search

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

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

2006-01-01

140

Carbon nanotube mechanical resonators  

NASA Astrophysics Data System (ADS)

Nano-electromechanical systems (NEMS) make use of electrically induced mechanical motion and vice versa. Carbon nanotubes are ideal building blocks of NEMS because of their unique (mechanical) properties and their low mass. This puts them in an unexplored regime of motion which approaches the fundamental detection limit set by quantum mechanics. At room temperature, we use mixing techniques to probe the bending-mode vibration of a suspended carbon nanotube; the gate voltage strains the carbon nanotube and thereby tunes the frequency. At low temperatures, mechanical vibrations are actuated by a nearby antenna and a record high Q-value of 150000 at a resonance frequency of 300 MHz is achieved. Electron tunneling and mechanical motion are strongly coupled resulting in single- electron tuning oscillations of the mechanical frequency and in energy transfer to the electrons causing mechanical damping. Strikingly, we also observe that a d.c. current through the nanotube spontaneously drives the mechanical resonator, exerting a force that is synchronized with the high-frequency vibrations.

van der Zant, Herre

2010-03-01

141

Emerging Dirac and Majorana fermions for carbon nanotubes with proximity-induced pairing and spiral magnetic field  

NASA Astrophysics Data System (ADS)

We study the low-energy band structure of armchair and small-band-gap semiconducting carbon nanotubes with proximity-induced superconducting pairing when a spiral magnetic field creates strong effective spin-orbit interactions from the Zeeman term and a periodic potential from the orbital part. We find that gapless Dirac fermions can be generated by variation of a single parameter. For a small-band-gap semiconducting tube with the field in the same plane, a nondegenerate zero mode at momentum k=0 can be induced, allowing for the generation of topologically protected Majorana fermion end states.

Egger, Reinhold; Flensberg, Karsten

2012-06-01

142

Stable geometries and magnetic properties of single-walled carbon nanotubes doped with 3d transition metals: A first-principles study  

Microsoft Academic Search

The interaction of 3d transition metal atoms and dimers with a single-walled armchair carbon nanotube has been investigated by first-principles density functional calculations. For Fe-, Co-, and Ni-doped (4,4) nanotubes, outside adsorption sites are the most favorable. The interactions are largely ferromagnetic for Fe and Co, with the local magnetic moments of the dimers being similar to the free dimers.

Yosuke Yagi; Tina M. Briere; Marcel H. Sluiter; Vijay Kumar; Amir A. Farajian; Yoshiyuki Kawazoe

2004-01-01

143

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

144

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

145

Conductance of Crossed Carbon Nanotubes  

Microsoft Academic Search

The effective Hamiltonian for two crossed nanotubes is derived in a k ·p scheme and the conductance between them is calculated in the Born approximation. The conductance is found to depend strongly on the crossing angle with large maxima at commensurate stacking of lattices of two nanotubes. In a magnetic field perpendicular to both nanotubes, these two maxima exhibit a

Takeshi Nakanishi; Tsuneya Ando

2001-01-01

146

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

147

Coaxial nanocable: Carbon nanotube core sheathed with boron nitride nanotube  

Microsoft Academic Search

A coaxial nanocable model consisting of conductive carbon nanotube core and boron nitride nanotube sheath is proposed by ab initio calculations. The conduction electron density is mainly concentrated on the inner carbon shell at the optimal interwall distance about 0.35 nm. The conductivity of the core carbon nanotube and the insulation of the boron nitride nanotube sheath are found to

Zhuhua Zhang; Wanlin Guo; Guo'an Tai

2007-01-01

148

Carbon Nanotubes Toxicity  

NASA Astrophysics Data System (ADS)

We describe current and possible future developments in nanotechnology for biological and medical applications. Nanostructured, composite materials for drug delivery, biosensors, diagnostics and tumor therapy are reviewed as examples, placing special emphasis on silica composites. Carbon nanotubes are discussed as a primary example of emerging nanomaterials for many of the above-mentioned applications. Toxicity effects of this novel nanomaterial are discussed and the need for further study of potential hazards for human health, professionally exposed workers and the environment is motivated.

Bellucci, Stefano

149

Super Growth Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Water assisted CVD (denoted as Super Growth) results in a significant enhanced catalyst activity and enlonged lifetime of the catalysts to synthesize carbon nanotubes. The high efficient growth results in massive growth of vertically-aligned single-walled nanotubes forests with heights up to 2.5 millimeters and carbon purity over 99.98%. Super Growth simultaneously addresses many critical problems such as scalability, purity, and cost, and opens up innumerable opportunities ranging from fundamental research to real applications. This presentation will provide an overview of our recent development of the ``Super Growth'' CVD. First, the synthesis of highly efficient impurity free SNWT forest will be described. Second, the growth dynamics will be explored with our recent advance in CNT synthesis, as well as characterizing the physical and chemical properties of SWNT forests. Third, various new forms of carbon nanotube material such as DWNT forests, SWNT solids made by utilizing the super-growth technique will be demonstrated with emphasis on their applications such as super-capacitors. Lastly, challenges and future projects that are planed will be summarized.

Hata, Kenji

2006-03-01

150

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

151

Heterostructured magnetic nanotubes.  

PubMed

Heterostructured magnetic tubes with submicrometer dimensions were assembled by the layer-by-layer deposition of polyelectrolytes and nanoparticles in the pores of track-etched polycarbonate membranes. Multilayers composed of poly(allylamine hydrochloride) and poly(styrene sulfonate) assembled at high pH (pH > 9.0) were first assembled into the pores of track-etched polycarbonate membranes, and then multilayers of magnetite (Fe3O4) nanoparticles and PAH were deposited. Transmission electron microscopy (TEM) confirmed the formation of multilayer nanotubes with an inner shell of magnetite nanoparticles. These tubes exhibited superparamagnetic characteristics at room temperature (300 K) as determined by a SQUID magnetometer. The surface of the magnetic nanotubes could be further functionalized by adsorbing poly(ethylene oxide)-b-poly(methacrylic acid) block copolymers. The separation and release behavior of low molecular weight anionic molecules (i.e., ibuprofen, rose bengal, and acid red 8) by/from the multilayer nanotubes were studied because these tubes could potentially be used as separation or targeted delivery vehicles. The magnetic tubes could be successfully used to separate (or remove) a high concentration of dye molecules (i.e., rose bengal) from solution by activating the nanotubes in acidic solution. The release of the anionic molecules in physiologically relevant buffer solution showed that whereas bulky molecules (e.g., rose bengal) release slowly, small molecules (i.e., ibuprofen) release rapidly from the multilayers. The combination of the template method and layer-by-layer deposition of polyelectrolytes and nanoparticles provides a versatile means to create functional nanotubes with heterostructures that can be used for separation as well as targeted delivery. PMID:17190494

Lee, Daeyeon; Cohen, Robert E; Rubner, Michael F

2007-01-01

152

The Mossbauer spectra of carbon nanotubes synthesize using ferrite catalyst  

NASA Astrophysics Data System (ADS)

The ferrite powder with honeycombed structure obtained by chemical combustion was used as catalyst to synthesize multi-walled carbon nanotubes by chemical vapor deposition. The magnetic components and characters of the the carbon nanotubes synthesized were investigated by X-ray diffraction (XRD), Mossbauer spectra and vibrating-sample magnetometer (VSM). The ferric components of the carbon nanotubes samples can be identified by Mossbauer spectra. The Mossbauer spectra of carbon nanotubes sample after purification contains two ferromagnetic sextet components corresponding to ?-Fe species and Fe3C (cementite) species. While the Mossbauer spectra of the carbon nanotubes sample before purification contains three ferromagnetic sextet components corresponding to ?-Fe species, Fe3C species and ?-Fe2O3. The saturation magnetization intensity Ms of carbon nanotubes sample after purification is decreased from 46.61 to 2.94 emu/g, but the coercive force increasd and reached 328Oe.

Zhang, Haiyan; Lin, Jiapeng; Peng, Zuxiong; Zeng, Guoxun; Pang, Jinshan; Chen, Yiming

2009-09-01

153

Functional materials based on carbon nanotubes: Carbon nanotube actuators and noncovalent carbon nanotube modification  

Microsoft Academic Search

Carbon nanotubes have attractive inherent properties that encourage the development of new functional materials and devices based on them. The use of single wall carbon nanotubes as electromechanical actuators takes advantage of the high mechanical strength, surface area and electrical conductivity intrinsic to these molecules. The work presented here investigates the mechanisms that have been discovered for actuation of carbon

Leonard S. Fifield

2003-01-01

154

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

155

The Mossbauer spectra of carbon nanotubes synthesize using ferrite catalyst  

Microsoft Academic Search

The ferrite powder with honeycombed structure obtained by chemical combustion was used as catalyst to synthesize multi-walled carbon nanotubes by chemical vapor deposition. The magnetic components and characters of the the carbon nanotubes synthesized were investigated by X-ray diffraction (XRD), Mossbauer spectra and vibrating-sample magnetometer (VSM). The ferric components of the carbon nanotubes samples can be identified by Mossbauer spectra.

Haiyan Zhang; Jiapeng Lin; Zuxiong Peng; Guoxun Zeng; Jinshan Pang; Yiming Chen

2009-01-01

156

Thermoelectric power in carbon nanotubes  

SciTech Connect

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

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

2009-04-15

157

Nanomachines based on carbon nanotubes  

NASA Astrophysics Data System (ADS)

The possibility for double-wall carbon nanotube to operate as the bolt and nut pair is studied. The barriers for relative motions of walls along the helical ``thread'' line and for jumps on neighbor helical lines are calculated as functions of wall lengths for the set of double-wall carbon nanotubes. The dynamics of relative motion of carbon nanotube walls along the helical line under the action of external forces is considered. Perforated nanodrill, variable nanoresistor and other nanotube based mechanical nanodevices using these motion are proposed. Possible operation modes of proposed nanodevices are discussed.

Lozovik, Yu. E.; Minogin, A. V.; Popov, A. M.

2003-06-01

158

Transverse wave propagation in elastically confined single-walled carbon nanotubes subjected to longitudinal magnetic fields using nonlocal elasticity models  

NASA Astrophysics Data System (ADS)

Lateral wave propagation in an elastically confined single-walled carbon nanotube (SWCNT) experiences a longitudinal magnetic field is examined using nonlocal Rayleigh, Timoshenko, and higher-order beam theories. The SWCNT is modeled via an equivalent continuum structure (ECS) and its interaction with the surrounding elastic medium is simulated via lateral and rotational continuous springs along its length. For the proposed models, the dimensionless governing equations describing transverse vibration of the SWCNT are constructed. Assuming harmonic solutions for the propagated sound waves, the dispersion equation associated with each model is obtained. Subsequently, the explicit expressions of the frequencies as well as the corresponding phase and group velocities, called characteristics of the waves, are derived for the proposed models. The influences of the slenderness ratio, the mean radius of the ECS, the small-scale parameter, the longitudinal magnetic field, the lateral and rotational stiffness of the surrounding matrix on the characteristics of flexural and shear waves are explored and discussed.

Kiani, Keivan

2012-08-01

159

Effect of the magnetic field on the edge states of zig-zag single wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

The influence of the static magnetic field on the edge states of finite zig-zag nanotubes has been explored theoretically by the tight-binding approximation. It was found that the magnetic field removes the degeneracy of the energy levels of the edge states. Investigation of the formation of new edge states by the magnetic field indicated the dependence of the number of these states on the length of a nanotube.

Pudlak, M.; Pincak, R.

2013-11-01

160

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...

161

Carbon nanotubes for power applications  

Microsoft Academic Search

Carbon nanotubes have been found to possess a wide variety of extremely remarkable properties, most notably high electrical and thermal conductivity, mechanical strength, and catalytic surface area. These properties imbue carbon nanotubes with tremendous potential for a variety of power generation and storage devices including: lithium-ion (Li+) batteries, polymeric solar cells, proton exchange membrane (PEM) fuel cells, and thermionic power

R. P. Raffaelle; B. J. Landi; J. D. Harris; S. G. Bailey; A. F. Hepp

2005-01-01

162

Acoustoelectric Effects in Carbon Nanotubes  

Microsoft Academic Search

We report observations of acoustoelectric effects in carbon nanotubes. We excite sound in mum long ropes of single walled carbon nanotubes suspended between two metallic contacts by applying radio-frequency electric field. The sound is detected by measuring either the dc resistance of the tubes in a region of strong temperature dependence (in the vicinity of superconducting or metal-insulator transition), or

B. Reulet; A. Yu. Kasumov; M. Kociak; R. Deblock; I. I. Khodos; Yu. B. Gorbatov; V. T. Volkov; C. Journet; H. Bouchiat

2000-01-01

163

Conductivity and magnetic susceptibility of nanotube/polypyrrole nanocomposites  

SciTech Connect

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

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

2000-04-01

164

PECVD Growth of Carbon Nanotubes.  

National Technical Information Service (NTIS)

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...

I. McAninch

2001-01-01

165

Electronic properties of carbon nanotube structures  

Microsoft Academic Search

An individual single-wall carbon nanotube has a periodic structure. Despite that, and because nanotubes can have different chiralities, systems of nanotubes can be highly non-periodic. This implies some difficulty in studying the electronic properties of nanotube structures. In this thesis, three nanotube systems are studied. The first problem presented in this thesis is that of a compositionally disordered nanotube rope.

Ahmed Abdel-Hameed Maarouf

2002-01-01

166

Fundamental transmitting properties of carbon nanotube antennas  

Microsoft Academic Search

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

G. W. Hanson

2005-01-01

167

Carbon-Nanotube Metrology  

Microsoft Academic Search

\\u000a Scientific and industrial metrology provided tools for technological growth and\\u000a innovation, by fostering competitiveness and creating a favorable environment for\\u000a scientific and industrial development. Every major country has its own metrology\\u000a institute to support companies in increasing their productivity and the quality of\\u000a their goods and services. The fast development of carbon-nanotube science and\\u000a applications urged studies on metrology, standardization

Ado Jorio; Esko Kauppinen; Abdou Hassanien

168

Structural, Electronic, and Magnetic Features of Platinum Alloy Strings Templated on A Boron-Doped Carbon Nanotube  

SciTech Connect

We present density-functional-theory calculations of structural, electronic, and magnetic properties of platinum-alloy strings templated on a boron-doped single-wall carbon nanotube (6,6) model, B-SWCNT(6,6). Our calculations show that the alloy strings demonstrate strong molecular recognition, forming well-defined covalent bonds with the substrate and lead to the self-assembly of stable monatomic chains. The electronic and magnetic features of the Pt-alloy string/B-SWCNT(6,6)composite systems are mainly controlled by the presence of a magnetic alloying element (i.e., Fe, Co, and Ru). By changing the composition of the Pt alloy, the easy magnetization axis of the system can oscillate between the directions parallel and perpendicular to the tube axis. Our studies suggest that pure transition-metal (TM) or TM-alloy strings anchored on a substrate via strong molecular interactions can still possess sizable magnetic anisotropy due to spin-orbital coupling effects.

An, Wei; Turner, C. H.

2010-05-25

169

Effect of Alignment on Transport Properties of Carbon Nanotube\\/Metallic Junctions  

Microsoft Academic Search

Ballistic and spin coherent transport in single walled carbon nanotubes (SWCNT) are predicted to enable high sensitivity single-nanotube devices for strain and magnetic field sensing. Based upon these phenomena, electron beam lithography procedures have been developed to study the transport properties of purified HiPCO single walled carbon nanotubes for development into sensory materials for nondestructive evaluation. Purified nanotubes are dispersed

Buzz Wincheski; Min Namkung; Jan Smits; Phillip Williams; Robert Harvey

170

Thermomagnetic effect in a twisted carbon nanotube  

NASA Astrophysics Data System (ADS)

A generation of magnetic field under application of thermal gradient in a twisted carbon nanotube (analog of Zavaritskii effect) is theoretically discussed. The analytical expression for twist angle dependence of the induced thermomagnetic field is obtained. The estimates of the model parameters suggest quite an optimistic possibility to experimentally realize the predicted effect.

Sergeenkov, S.; Araujo-Moreira, F. M.

2013-03-01

171

Raman Scattering in Carbon Nanotubes  

Microsoft Academic Search

The vibrational properties of single-walled carbon nanotubes reflect the electron and phonon confinement as well as the cylindrical\\u000a geometry of the tubes. Raman scattering is one of the prime techniques for studying the fundamental properties of carbon tubes\\u000a and nanotube characterization. The most important phonon for sample characterization is the radial-breathing mode, an in-phase\\u000a radial movement of all carbon atoms.

Christian Thomsen; Stephanie Reich

172

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

173

Biophilic carbon nanotubes.  

PubMed

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

Mallick, Kaushik; Strydom, André M

2013-01-14

174

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

175

Coatings for Carbon Nanotubes.  

National Technical Information Service (NTIS)

A coated nanotube that includes an inner nanotube having an exterior surface, and a plasma deposited layer covering at least part of the exterior surface of the inner nanotube. Also, a method of making a coated nanotube, the method where the method includ...

C. P. Collier K. P. Giapis M. J. Esplandiu

2005-01-01

176

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

177

Carbon nanotubes: engineering biomedical applications.  

PubMed

Carbon nanotubes (CNTs) are cylinder-shaped allotropic forms of carbon, most widely produced under chemical vapor deposition. They possess astounding chemical, electronic, mechanical, and optical properties. Being among the most promising materials in nanotechnology, they are also likely to revolutionize medicine. Among other biomedical applications, after proper functionalization carbon nanotubes can be transformed into sophisticated biosensing and biocompatible drug-delivery systems, for specific targeting and elimination of tumor cells. This chapter provides an introduction to the chemical and electronic structure and properties of single-walled carbon nanotubes, followed by a description of the main synthesis and post-synthesis methods. These sections allow the reader to become familiar with the specific characteristics of these materials and the manner in which these properties may be dependent on the specific synthesis and post-synthesis processes. The chapter ends with a review of the current biomedical applications of carbon nanotubes, highlighting successes and challenges. PMID:22093220

Gomez-Gualdrón, Diego A; Burgos, Juan C; Yu, Jiamei; Balbuena, Perla B

2011-01-01

178

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

179

Arc discharge for carbon nanotube synthesis  

NASA Astrophysics Data System (ADS)

The arc discharge is one of the most practical methods for single wall nanotube (SWNT) synthesis. This method yields highly graphitized tubes, because the manufacturing process occurs at a very high temperature. Arc-produced carbon nanotubes have fewer structural defects than those produced by low temperature techniques such chemical vapor deposition (CVD). Most likely this is due to fast growth that prevents defect formation. The most important arc process for SWNT synthesis is the anode erosion. It is shown that the dependence of the anode erosion rate on arc current and background pressure can be strongly affected by the magnetic field. The effect of the magnetic field on the SWNT properties and SWNT production yield is investigated. A theoretical model suggests that a magnetic field may lead to longer nanotubes.

Keidar, Michael; Raitses, Yevgeny; Tao, Liang; Fetterman, Abraham; Waas, Anthony

2006-10-01

180

Carbon Nanotube Foam and Method of Making and Using Thereof.  

National Technical Information Service (NTIS)

A method of making a carbon nanotube structure includes providing an array of substantially aligned carbon nanotubes, wetting the array with a liquid, and evaporating the liquid to form the carbon nanotube structure having a pattern in the carbon nanotube...

A. Carrillo B. Wei N. Chakrapani P. Ajayan R. S. Kane

2004-01-01

181

Carbon nanotube array smart materials  

NASA Astrophysics Data System (ADS)

Highly aligned multi-wall carbon nanotube arrays up to 4 mm tall were synthesized on Si wafers using a chemical vapor deposition process with water delivery. Based on the long nanotube arrays, several prototype smart materials were developed including a biosensor, electrochemical actuator, and nanotube probes. The biosensor was formed by casting epoxy into a nanotube array and polishing the ends of the nanotubes. This electrode produced a near ideal sigmoidal cyclic voltammogram. Nanotube electrodes were then used to form a label-free immunosensor based on electrochemical impedance spectroscopy. The nanotube array immunosensor has good sensitivity, but decreasing the array size and improving the biofunctionalization is expected to dramatically increase the reproducibility and sensitivity. The electrochemical actuator was formed by bonding an electrode to a 1mm square by 4 mm long as-grown nanotube array post. The nanotube array actuator operated up to 10 Hz in a 2 M NaCl solution. With a driving voltage of 2 volts, the actuator produced 0.15% strain. Finally, nanotube bundles are being welded to tungsten tips and put inside glass needles for use as probes for biosensors and electrophysiology applications. All the smart materials applications discussed are recent, and further development is expected to yield improved performance and commodity level practical devices.

Yun, YeoHeung; Bange, Adam; Shanov, Vesselin N.; Heineman, William R.; Halsall, H. Brian; Pixley, Sarah K.; Behbehani, Michael; Dong, Zhongyun; Tu, Yi; Yarmolenko, Sergey; Neralla, Sudhir; Schulz, Mark J.

2006-04-01

182

Carbon Nanotube Actuators  

NASA Astrophysics Data System (ADS)

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

Baughman, Ray H.

2000-03-01

183

Thermal Properties of Carbon Nanotubes  

Microsoft Academic Search

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

Mohamed. Osman; Aron W. Cummings; Deepak Srivastava

184

Overview of Nanotechnology: Carbon Nanotubes  

NSDL National Science Digital Library

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

2011-09-21

185

Carbon Nanotube Electronics and Optoelectronics  

Microsoft Academic Search

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

Stefan Heinze; Jerry Tersoff; Phaedon Avouris

2005-01-01

186

Toxicity of carbon nanotubes.  

PubMed

Carbon nanotubes (CNTs) find their extensive application as a promising material in medicine due to unique characteristics. However, such materials have been accompanied with potentially hazardous effects on human health. The toxicity of CNTs may vary depending on their structural characteristics, surface properties and chemical composition. To gain insight into the toxicity of CNTs in vivo and in vitro, we summarize contributing factors for the toxic effects of CNTs in this review. In addition, we elaborate on the toxic effects and mechanisms in target sites at systemic, organic, cellular, and biomacromolecule levels. Various issues are reported to be effected when exposed to CNTs including (1) blood circulation, (2) lymph circulation, (3) lung, (4) heart, (5) kidney, (6) spleen, (7) bone marrow, and (8) blood brain barrier. Though there have been published reports on the toxic effects of CNTs to date, more studies will still be needed to gain full understanding of their potential toxicity and underlying mechanisms. PMID:24016107

Wang, Jing; Xu, Yuanzhi; Yang, Zhi; Huang, Renhuan; Chen, Jing; Wang, Raorao; Lin, Yunfeng

2013-08-01

187

Carbon Nanotube based Nanotechnolgy  

NASA Astrophysics Data System (ADS)

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

Meyyappan, M.

2000-10-01

188

High-Performance Carbon Nanotube Fiber  

Microsoft Academic Search

With their impressive individual properties, carbon nanotubes should form high-performance fibers. We explored the roles of nanotube length and structure, fiber density, and nanotube orientation in achieving optimum mechanical properties. We found that carbon nanotube fiber, spun directly and continuously from gas phase as an aerogel, combines high strength and high stiffness (axial elastic modulus), with an energy to breakage

Krzysztof Koziol; Juan Vilatela; Anna Moisala; Marcelo Motta; Philip Cunniff; Michael Sennett; Alan Windle

2007-01-01

189

Controlled growth of carbon nanotubes.  

PubMed

Carbon nanotubes have extraordinary mechanical and electronic properties and hold great promise for future applications. The most important aspects of this structure are its low density, high aspect ratio, one dimensionality, high mechanical strength and high electrical and thermal conductivity. We present a short, state-of-the-art account of tailored nanotube growth. To provide these properties in real devices there exists a need for producing nanotubes on substrates. The challenge in the creation of mesoscale nanotube-based architectures and tailored nanotube networks consisting of thousands of tubes in a predefined order is obviously great. Currently, chemical vapour deposition (CVD) appears to be the most powerful method for achieving such required structures. We describe our work on a new synthesis method, based on catalytic CVD using mainly gas-phase catalyst delivery. Gas-phase catalyst delivery allows us to assemble single-walled and multi-walled carbon nanotubes in predetermined multiple orientations on substrates to build one- to three-dimensional architectures. We are able to control, to a large extent, the types of nanotubes produced, their lengths, locations and their orientations. The ability to make mesoscale architectures with nanotubes should lead us to develop applications in areas such as nano-electromechanical systems. PMID:15370475

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

2004-10-15

190

Multifunctional carbon-nanotube cellular endoscopes  

NASA Astrophysics Data System (ADS)

Glass micropipettes, atomic force microscope tips and nanoneedles can be used to interrogate cells, but these devices either have conical geometries that can damage cells during penetration or are incapable of continuous fluid handling. Here, we report a carbon-nanotube-based endoscope for interrogating cells, transporting fluids and performing optical and electrochemical diagnostics at the single organelle level. The endoscope, which is made by placing a multiwalled carbon nanotube (length, 50-60 µm) at the tip of a glass pipette, can probe the intracellular environment with a spatial resolution of ~100 nm and can also access organelles without disrupting the cell. When the nanotube is filled with magnetic nanoparticles, the endoscope can be remotely manoeuvered to transport nanoparticles and attolitre volumes of fluids to and from precise locations. Because they are mounted on conventional glass micropipettes, the endoscopes readily fit standard instruments, creating a broad range of opportunities for minimally invasive intracellular probing, drug delivery and single-cell surgery.

Singhal, Riju; Orynbayeva, Zulfiya; Kalyana Sundaram, Ramalingam Venkat; Niu, Jun Jie; Bhattacharyya, Sayan; Vitol, Elina A.; Schrlau, Michael G.; Papazoglou, Elisabeth S.; Friedman, Gary; Gogotsi, Yury

2011-01-01

191

Phase diagrams of magnetic nanotubes  

NASA Astrophysics Data System (ADS)

Analytical expressions for the total magnetic energy of two characteristic internal configurations of nanometric tubes are calculated. A magnetic phase diagram with respect to the aspect ratio of the tubes is obtained which allows a discussion about the possibility of getting ensembles of nanotubes with low coercive fields. A comparison with recently reported coercive fields of three different cobalt nanotube arrays agrees well with the phase diagram derived here.

Escrig, J.; Landeros, P.; Altbir, D.; Vogel, E. E.; Vargas, P.

2007-01-01

192

Magnetostatic interactions between magnetic nanotubes  

NASA Astrophysics Data System (ADS)

The investigation of interactions between magnetic nanotubes is complex and often involves substantial simplifications. In this letter an analytical expression for the magnetostatic interaction, taking into account the geometry of the tubes, has been obtained. This expression allows for the definition of a critical vertical separation for relative magnetization between nanotubes and can be used for tailoring barcode-type nanostructures with prospective applications such as biological separation and transport.

Escrig, J.; Allende, S.; Altbir, D.; Bahiana, M.

2008-07-01

193

Electronic specific heat of single-walled carbon nanotubes  

Microsoft Academic Search

The electronic structure of single-walled carbon nanotubes is calculated by the tight-binding model. A single-walled carbon nanotube could drastically change from a metal to a semiconductor or vice versa during the variation of magnetic flux. The low-temperature electronic specific heat thus exhibits the rich temperature and magnetic-flux dependence. There are four kinds of temperature dependence in the presence of the

Ming-Fa Lin; Kenneth Wen-Kai Shung; Der-San Chuu

1996-01-01

194

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

Microsoft Academic Search

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

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

2009-01-01

195

Stability of the thin partitioned carbon nanotubes.  

PubMed

We report on the research of the stability of partitioned (bamboo-like) carbon nanotubes with different diameters. The stability of the partitioned carbon nanotubes of the smallest diameter were determined by the tight-binding method. For the prediction of the destruction regions of the bamboo-like nanotubes atomic framework subjected to strain the new original method of the calculation of the local stress of atomic network was developed. Using this method it was shown that partitioned carbon nanotubes with a diameter of 2.02 nm are stable. These partitioned carbon nanotubes with chirality (15,15) are the most stable partitioned carbon nanotubes with the smallest diameter. PMID:23912339

Glukhova, O E; Kolesnikova, A S; Slepchenkov, M M

2013-08-04

196

Properties of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

197

Carbon nanotube computer.  

PubMed

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

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

2013-09-26

198

Noncovalent Sidewall Functionalization of Carbon Nanotubes.  

National Technical Information Service (NTIS)

Carbon nanotubes are functionalized in a broadly applicable manner. According to an example embodiment of the present invention, single-wall carbon nanotubes (SWNTs) are noncovalently functionalized. The functionalized SWNTs are highly versatile, being us...

H. Dai R. J. Chen

2002-01-01

199

Plasticity and Kinky Chemistry of Carbon Nanotubes.  

National Technical Information Service (NTIS)

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 nanotub...

D. Srivastava F. Dzegilenko

2004-01-01

200

Carbon nanotube\\/carbon fiber hybrid multiscale composites  

Microsoft Academic Search

Carbon nanotubes were grown directly on carbon fibers using chemical vapor deposition. When embedded in a polymer matrix, the change in length scale of carbon nanotubes relative to carbon fibers results in a multiscale composite, where individual carbon fibers are surrounded by a sheath of nanocomposite reinforcement. Single-fiber composites were fabricated to examine the influence of local nanotube reinforcement on

E. T. Thostenson; W. Z. Li; D. Z. Wang; Z. F. Ren; T. W. Chou

2002-01-01

201

The electrochemical impedance measurements of carbon nanotubes  

Microsoft Academic Search

The two types of carbon nanotube electrodes have been studied as a function of frequency and the open circuit cell voltage. Nyquist plots measured from the closed carbon nanotubes electrodes at different potentials include only one semicircle that is attributed the adsorption phenomenon at the surface only. However, the Nyquist plots measured from the opened carbon nanotubes electrodes at different

Zhan-hong Yang; Hao-qing Wu

2001-01-01

202

Lattice specific heat of carbon nanotubes  

Microsoft Academic Search

The lattice specific heat in carbon nanotubes is evaluated within the microscopic model proposed by Mahan and Jeon, published in the Physical Review B, in 2004. Phonons are considered for single wall carbon nanotubes in armchair configuration. As expected, low temperature and high temperature regions show different behaviour of specific heat. Carbon nanotubes are also displaying a very interesting lattice

Amelia Carolina Sparavigna

2008-01-01

203

Lattice specific heat of carbon nanotubes  

Microsoft Academic Search

The lattice specific heat of carbon nanotubes is evaluated within the microscopic model proposed by Mahan and Jeon, published in the Physical Review B, in 2004. Phonons are considered for a single wall carbon nanotube in the armchair configuration. As expected, low temperature and high temperature regions show different behavior of specific heat. Carbon nanotubes are also displaying a very

A. Sparavigna

2006-01-01

204

Carbon Nanotube Membranes for Water Purification  

Microsoft Academic Search

Carbon nanotubes are an excellent platform for the fundamental studies of transport through channels commensurate with molecular size. Water transport through carbon nanotubes is also believed to be similar to transport in biological channels such as aquaporins. I will discuss the transport of gas, water and ions through microfabricated membranes with sub-2 nanometer aligned carbon nanotubes as ideal atomically-smooth pores.

Olgica Bakajin

2009-01-01

205

OPENING MULTIWALL CARBON NANOTUBES WITH ELECTRON BEAM  

Microsoft Academic Search

A new method of nanomachining and opening multiwall carbon nanotubes (MWNTs) has been demonstrated. The puncture is accomplished by moving a converged electron beam in transmission electron microscope (TEM) onto the water inclusion in the multiwall carbon nanotube. The high resolution TEM images show that the reaction between the water inclusion and the walls of the carbon nanotube is the

H. YE; N. NAGUIB; Y. GOGOTSI

206

EDITORIAL: Focus on Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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

2003-09-01

207

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

PubMed

Soluble starch-functionalized multiwall carbon nanotube composites (MWCNT-starch) were prepared to improve the hydrophilicity and biocompatibility of MWCNTs. Characterization of the MWCNT-starch by Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM) and thermogravimetric analysis (TG), showed that the starch component (about 14.3 wt%) was covalently grafted onto the surface of MWCNT. MWCNT-starch-iron oxide composites, intended for use as adsorbents for the removal of dyes from aqueous solutions, were prepared by synthesizing iron oxide nanoparticles at the surface of MWCNT-starch. Starch acts as a template for growth of iron oxide nanoparticles which are uniformly dispersed on the surface of the MWCNT-starch. MWCNT-starch-iron oxide exhibits superparamagnetic properties with a saturation magnetization (23.15 emu/g) and better adsorption for anionic methyl orange (MO) and cationic methylene blue (MB) dyes than MWCNT-iron oxide. PMID:21255925

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

2011-01-05

208

Reversal modes in magnetic nanotubes  

NASA Astrophysics Data System (ADS)

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 mechanisms: The propagation of a transverse domain wall or propagation of a vortex domain wall depending on the internal and external radii of the tube.

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

2007-03-01

209

Functionalized carbon nanotubes containing isocyanate groups  

Microsoft Academic Search

Functionalized carbon nanotubes containing isocyanate groups can extend the nanotube chemistry, and may promote their many potential applications such as in polymer composites and coatings. This paper describes a facile method to prepare functionalized carbon nanotubes containing highly reactive isocyanate groups on its surface via the reaction between toluene 2,4-diisocyanate and carboxylated carbon nanotubes. Fourier-transformed infrared spectroscopy (FTIR) and X-ray

Chungui Zhao; Lijun Ji; Huiju Liu; Guangjun Hu; Shimin Zhang; Mingshu Yang; Zhenzhong Yang

2004-01-01

210

Carbon nanotube: the inside story.  

PubMed

Carbon nanotubes (CNTs) were serendipitously discovered as a byproduct of fullerenes by direct current (DC) arc discharge; and today this is the most-wanted material in the nanotechnology research. In this brief review, I begin with the history of the discovery of CNTs and focus on CNTs produced by arc discharge in hydrogen atmosphere, which is little explored outside my laboratory. DC arc discharge evaporation of pure graphite rod in pure hydrogen gas results in multi-walled carbon nanotubes (MWCNTs) of high crystallinity in the cathode deposit. As-grown MWCNTs have very narrow inner diameter. Raman spectra of these MWCNTs show high-intensity G-band, unusual high-frequency radial breathing mode at 570 cm(-1), and a new characteristic peak near 1850 cm(-1). Exciting carbon nanowires (CNWs), consisting of a linear carbon chain in the center of MWCNTs are also produced. Arc evaporation of graphite rod containing metal catalysts results in single-wall carbon nanotubes (SWCNTs) in the whole chamber like macroscopic webs. Two kinds of arc method have been developed to produce SWCNTs: Arc plasma jet (APJ) and Ferrum-Hydrogen (FH) arc methods. Some new purification methods for as-produced SWCNTs are reviewed. Finally, double-walled carbon nanotubes (DWCNTs) are also described. PMID:20355364

Ando, Yoshinori

2010-06-01

211

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

212

The Electronic Specific Heat of single-walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

The electronic structure of single-walled carbon nanotubes is calculated by the tight-binding model. A single-walled carbon nanotube could drastically change from a metal (semiconductor) to a semiconductor (metal) during the variation of magnetic flux. The low-temperature electronic specific heat thus exhibits the rich temperature and magnetic-flux dependence. There are four kinds of temperature dependence in the presence of the magnetic field, mainly due to the interaction between spin and magnetic field. Furthermore, the flux-dependent specific heat exhibits the pronounced oscillatory behavior including asymmetric two-peak structures. These structures strongly depends on the characteristics of the subbands nearest the Fermi level.

Lin, Ming-Fa; Shung, Kenneth Wen-Kai; Chuu, Der-San

1996-03-01

213

Supported lipid bilayer/carbon nanotube hybrids  

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

214

Carbon Nanotube Doped Lithium Ion Batteries  

Microsoft Academic Search

We have characterized thin film lithium ion batteries that contain high purity single wall carbon nanotube-doped polymer anodes. Highly purified single-walled carbon nanotubes (SWCNT) were obtained through chemical refinement of soot generated by pulsed laser ablation. The purity of the nanotubes was determined via thermogravimetric analysis, two wavelength Raman spectroscopy, spectrophotometry, scanning electron microscopy and transmission electron microscopy. The specific

Ryne P. Raffaelle; Ron Difelice; William R. van Derveer; Tom Gennett; Jeff Maranchi; Prashant Kumta; Aloysius F. Hepp

2002-01-01

215

Adsorption of gases in carbon nanotubes  

Microsoft Academic Search

This work addresses the physical adsorption of gases in carbon nanotubes. In the confining environment of nanotube bundles, adsorbed atoms exhibit behavior characteristic of 1, 2, and 3 dimensions as a function of thermodynamic parameters, geometry, and microscopic variables. Many body interactions among quasi-1D phases of gases adsorbed within carbon nanotubes and the corresponding implications for condensation transition are investigated.

Milen Kalushkov Kostov

2003-01-01

216

Neat single wall carbon nanotube fiber  

Microsoft Academic Search

Here we report the production of the first ever macroscopic single wall carbon nanotube fibers that consist of only nanotubes without any underlying surfactant or polymer substructure. The single wall carbon nanotube (SWNT) fibers were spun from the dispersion of purified SWNTs with concentrations from 4wt(100spinning techniques. The SWNTs fibers have high alignment and good electrical conductivity.

Hua Fan; Lars Ericson; Virginia Davis; Haiqing Peng; Nicholas Parra-Vasquez; Joseph Sulpizio; Sivarajan Ramesh; Wade Adams; Matteo Pasquali; Howard Schmidz; Robert Hauge; Richard Smalley

2004-01-01

217

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

2013-09-01

218

Thermal conductivity and thermal rectification in unzipped carbon nanotubes  

Microsoft Academic Search

We study the thermal transport in completely unzipped carbon nanotubes, which are called graphene nanoribbons, partially unzipped carbon nanotubes, which can be seen as carbon-nanotube-graphene-nanoribbon junctions, and carbon nanotubes by using molecular dynamics simulations. It is found that the thermal conductivity of a graphene nanoribbon is much less than that of its perfect carbon nanotube counterparts because of the localized

Xiaoxi Ni; Gang Zhang; Baowen Li

2011-01-01

219

Functionalized carbon nanotubes containing isocyanate groups  

SciTech Connect

Functionalized carbon nanotubes containing isocyanate groups can extend the nanotube chemistry, and may promote their many potential applications such as in polymer composites and coatings. This paper describes a facile method to prepare functionalized carbon nanotubes containing highly reactive isocyanate groups on its surface via the reaction between toluene 2,4-diisocyanate and carboxylated carbon nanotubes. Fourier-transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed that reactive isocyanate groups were covalently attached to carbon nanotubes. The content of isocyanate groups were determined by chemical titration and thermogravimetric analysis (TGA)

Zhao Chungui [Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Number 2, Zhongguancun North 1 St., Beijing 100080 (China); Ji Lijun [Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Number 2, Zhongguancun North 1 St., Beijing 100080 (China); Liu Huiju [Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Number 2, Zhongguancun North 1 St., Beijing 100080 (China); Hu Guangjun [Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Number 2, Zhongguancun North 1 St., Beijing 100080 (China); Zhang Shimin [Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Number 2, Zhongguancun North 1 St., Beijing 100080 (China); Yang Mingshu [Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Number 2, Zhongguancun North 1 St., Beijing 100080 (China)]. E-mail: yms@iccas.ac.cn; Yang Zhenzhong [Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Number 2, Zhongguancun North 1 St., Beijing 100080 (China)]. E-mail: yangzz@iccas.ac.cn

2004-12-01

220

Carbon nanotubes soldering for high performance composites  

NASA Astrophysics Data System (ADS)

Individual carbon nanotubes exhibit very interesting mechanical and electric properties. At present carbon nanotubes are available in large quantities and, in principle, they should find their way as filler of choice for polymer composites. Yet, in practice, carbon nanotube composites often show deceiving properties. In this presentation we will introduce the concept of carbon nanotubes soldering discuss some promising examples of its applications to design high performance composites. In particular we will demonstrate the utility of nanotube soldering to attain high temperature mechanical and solvent resistance, properties essential for many composite applications. Work done in collaboration with Thomas P'eri'e and Sylvie Tenc'e-Girault.

Leibler, Ludwik

2010-03-01

221

Carbon Nanotube Arrays for Thermal Management Applications.  

National Technical Information Service (NTIS)

The work was designed towards creating aligned multiwalled carbon nanotube arrays by chemical vapor deposition (CVD) of xylene hydrocarbon precursor and simultaneous vapor phase delivery of catalyst particles. Low density nanotube arrays as well as highly...

P. M. Ajayan

2008-01-01

222

Continuum model of polygonization of carbon nanotubes  

NASA Astrophysics Data System (ADS)

We derive a simple continuum model of multiwalled carbon nanotubes that takes into account both strong covalent bonds within graphene layers and weak bonds between graphene layers. The model predicts polygonization of cross sections of large multiwalled nanotubes.

Golovaty, Dmitry; Talbott, Shannon

2008-02-01

223

Chemical Bonding of Polymer on Carbon Nanotube.  

National Technical Information Service (NTIS)

Recently, carbon nanotubes are considered as nanoscale fibers, which can strengthen polymer composite materials. Nanotube-polymer composite materials can be used for micron scale devices with designed mechanical properties and smart polymer coating to pro...

C. Wei K. Cho

2001-01-01

224

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

225

Exciton Photophysics of Carbon Nanotubes  

Microsoft Academic Search

The goal of this chapter is to review the importance of excitons to single-wall carbon nanotube (SWNT) optics. We have developed the presentation for both researchers in the SWNT field who want to learn more about the unusual aspects of SWNT exciton photophysics and researchers more knowledgeable about the physics of excitons, but not about SWNT physics. Excitons in SWNTs

Mildred S. Dresselhaus; Gene Dresselhaus; Riichiro Saito; Ado Jorio

2007-01-01

226

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

Microsoft Academic Search

Soluble starch-functionalized multiwall carbon nanotube composites (MWCNT-starch) were prepared to improve the hydrophilicity and biocompatibility of MWCNTs. Characterization of the MWCNT-starch by Fourier transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM) and thermogravimetric analysis (TG), showed that the starch component (about 14.3wt%) was covalently grafted onto the surface of MWCNT. MWCNT-starch-iron oxide composites, intended

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

2011-01-01

227

FTIR studies of nitrogen doped carbon nanotubes  

Microsoft Academic Search

Purified and defect free carbon nanotubes have great potential for applications in electronic, polymer composites and biological sciences. The removal of impurities (carbon nanoparticles and amorphous carbon) is an important step before the CNT applications can be realized. We report the results of FTIR and TGA\\/DTA studies of the impurities present in the carbon nanotubes. The multiwalled CNTs were grown

Abha Misra; Pawan K. Tyagi; M. K. Singh; D. S. Misra

2006-01-01

228

Carbon Nanotubes Interactions: Theory and Applications  

NASA Astrophysics Data System (ADS)

A theoretical framework describing the carbon nanotubes interaction, involving two distinct approaches, is presented. Based on the results obtained practical applications using carbon nanotubes are further proposed. First a classical approach is employed for different geometrical configurations, such as parallel or concentric carbon nanotubes. For all the cases analytical expressions for the systems potential energies are derived. The results obtained using the classical approach are used to propose a few practical applications. These applications include a non-contact device for profiling surfaces and a custom telescopic double wall carbon nanotube for nanolithography applications. It is expected that such devices can be effectively used with major advantages. Next the interaction between nanotubes is considered using a quantum electrodynamics approach suitable for dispersing and absorbing media. Each carbon nanotube is characterized by its individual full dielectric response. The method also allows taking into account the full carbon nanotube cylindrical geometry by imposing the appropriate boundary conditions at the nanotubes surfaces. It is found that at small nanotube separations, similar to their equilibrium distances, the interaction is dominated by the collective excitations in the electron energy loss spectra originating from interband transitions. Furthermore, it is shown that the collective surface excitations and their chirality dependent characteristics play a profound role in the interaction strength in double wall carbon nanotube systems. The obtained results are in good agreement with experimental measurements on determining the chirality of individual double wall carbon nanotubes.

Popescu, Adrian

229

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

230

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

231

Local gate control in carbon nanotube quantum devices  

NASA Astrophysics Data System (ADS)

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

Biercuk, Michael Jordan

232

Carbon nanotube cathode with capping carbon nanosheet  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

233

Carbon Nanotubes - Polymer Composites with Enhanced Conductivity using Functionalized Nanotubes  

NASA Astrophysics Data System (ADS)

Individual carbon nanotubes show superior electrical, mechanical and thermal properties [1]. Composite materials using carbon nanotubes as fillers are predicted to show similar superior properties. However, realization of such composites has been plagued by poor dispersion of carbon nanotubes in solvents and in polymer matrices. We have developed a method to homogenously disperse carbon nanotubes in polymer matrices using functionalized nanotubes [2]. Thin films of functionalized single walled nanotubes (SWNT) - polystyrene composites and functionalized SWNT - polycarbonate composites were prepared using solution evaporation and spin coating. Both of the composites show several orders of magnitude increase in conductivity for less than 1 wt thresholds of the composites are less than 0.2 wt nanotubes. We attribute the enhanced conduction to the superior dispersion of the functionalized nanotubes in the polymer matrix and to the reduced nanotube waviness resulting from the rigid backbone of the conjugated polymer. References: [1]. R. H. Baughman, A. A. Zakhidov and W. A. de Heer, Science v297, p787 (2002); [2]. J. Chen, H. Liu, W. A. Weimer, M. D. Halls, D. H. Waldeck and G. C. Walker, J. Am. Chem. Soc. v124, p9034 (2002).

Ramasubramaniam, Rajagopal; Chen, Jian; Gupta, Rishi

2003-03-01

234

Twisting Graphene into Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

235

Dispersions, novel nanomaterial sensors and nanoconjugates based on carbon nanotubes  

Microsoft Academic Search

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

Ignác Capek

2009-01-01

236

FUNCTIONALIZATION OF CARBON NANOTUBES: SINGLE ATOM ADSORPTION  

Microsoft Academic Search

Unusual mechanical and electronic properties of carbon nanotubes promise a new generation of materials with potential applications in nanotechnology. The physical and chemical properties can also be efficiently engineered by the adsorption of atoms or molecules so that carbon nanotubes can be functionalized. Using state-of-the-art first principles total energy calculations, we show the single-wall carbon nanotubes (SWNTs) can be functionalized

Sefa Dag; Engin Durgun; Taner Yildirim; Salim Ciraci

237

Formylation of single-walled carbon nanotubes  

Microsoft Academic Search

Formyl or aldehyde groups are transferred to the surface of single-walled carbon nanotubes (SWCNTs) by reaction of reduced carbon nanotubes with N-formylpiperidine. This could open the way for more versatile chemical modification reactions of carbon nanotubes than is currently possible using functionalization methods reported to date. The formylated SWCNTs were characterized by thermogravimetric analysis–mass spectrometry and Raman, UV–vis–NIR and FTIR

Mustafa K. Bayazit; Anil Suri; Karl S. Coleman

2010-01-01

238

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

239

Applications of carbon nanotubes for cancer research  

Microsoft Academic Search

Carbon nanotubes have many unique properties such as high surface area, hollow cavities, and excellent mechanical and electrical\\u000a properties. Interfacing carbon nanotubes with biological systems could lead to significant applications in various disease\\u000a diagnoses. Significant progress in interfacing carbon nanotubes with biological materials has been made in key areas such\\u000a as aqueous solubility, chemical and biological functionalization for biocompatibility and

Kasif Teker; Ranjani Sirdeshmukh; Kousik Sivakumar; Shoaxin Lu; Eric Wickstrom; Hsin-Neng Wang; Tuan Vo-Dinh; Balaji Panchapakesan

2005-01-01

240

Electronic and structural properties of carbon nanotubes  

Microsoft Academic Search

Recent developments using synthetic methods typical of fullerene production have been used to generate graphitic nanotubes with diameters on the order of fullerene diameters: “carbon nanotubes.” The individual hollow concentric graphitic nanotubes that comprise these fibers can be visualized as constructed from rolled-up single sheets of graphite. We discuss the use of helical symmetry for the electronic structure of these

J. W. Mintmire; C. T. White

1995-01-01

241

Novel Magnetic Properties in Multi-Walled Carbon Nanotube Mats:. Consistent with the Paramagnetic Meissner Effect due to Ultrahigh-Temperature Superconductivity  

NASA Astrophysics Data System (ADS)

We report magnetic measurements up to 1200 K on iron-contaminated multi-walled carbon nanotube mats with a Quantum Design vibrating sample magnetometer. Extensive magnetic data consistently show a ferrromagnetic transition at about 1000 K and a ferromagnetic-like transition at about 1275 K. The ferromagnetic transition at about 1000 K is associated with an Fe impurity phase and its saturation magnetization is in quantitative agreement with the Fe concentration measured by an inductively coupled plasma mass spectrometer. On the other hand, the saturation magnetization for the ferromagnetic-like phase (at 1275 K) is about four orders of magnitude larger than that expected from the measured concentration of Co or CoFe. We show that this ultrahigh-temperature ferromagnetic-like behavior cannot be explained by ferromagnetism of any Fe-carbon phases, carbon-based phases, or magnetic impurities, but is consistent with the paramagnetic Meissner effect (orbital ferromagnetism) due to the existence of ? Josephson junctions in a granular superconductor.

Zhao, Guo-Meng; Beeli, Pieder

242

Novel Magnetic Properties in Multi-Walled Carbon Nanotube Mats:. Consistent with the Paramagnetic Meissner Effect due to Ultrahigh-Temperature Superconductivity  

NASA Astrophysics Data System (ADS)

We report magnetic measurements up to 1200 K on iron-contaminated multi-walled carbon nanotube mats with a Quantum Design vibrating sample magnetometer. Extensive magnetic data consistently show a ferrromagnetic transition at about 1000 K and a ferromagnetic-like transition at about 1275 K. The ferromagnetic transition at about 1000 K is associated with an Fe impurity phase and its saturation magnetization is in quantitative agreement with the Fe concentration measured by an inductively coupled plasma mass spectrometer. On the other hand, the saturation magnetization for the ferromagnetic-like phase (at 1275 K) is about four orders of magnitude larger than that expected from the measured concentration of Co or CoFe. We show that this ultrahigh-temperature ferromagnetic-like behavior cannot be explained by ferromagnetism of any Fe-carbon phases, carbon-based phases, or magnetic impurities, but is consistent with the paramagnetic Meissner effect (orbital ferromagnetism) due to the existence of ? Josephson junctions in a granular superconductor.

Zhao, Guo-Meng; Beeli, Pieder

2010-12-01

243

Thermal properties of carbon nanotubes and nanotube-based materials  

Microsoft Academic Search

.   The thermal properties of carbon nanotubes are directly related to their unique structure and small size. Because of these\\u000a properties, nanotubes may prove to be an ideal material for the study of low-dimensional phonon physics, and for thermal management,\\u000a both on the macro- and the micro-scale. We have begun to explore the thermal properties of nanotubes by measuring the

J. Hone; M. C. Llaguno; M. J. Biercuk; A. T. Johnson; B. Batlogg; Z. Benes; J. E. Fischer

2002-01-01

244

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

2011-10-13

245

Processing carbon nanotubes with holographic optical tweezers  

Microsoft Academic Search

We report the first demonstration that carbon nanotubes can be trapped and\\u000amanipulated by optical tweezers. This observation is surprising because\\u000aindividual nanotubes are substantially smaller than the wavelength of light,\\u000aand thus should not be amenable to optical trapping. Even so, nanotube bundles,\\u000aand perhaps even individual nanotubes, can be transported at high speeds,\\u000adeposited onto substrates, untangled, and

Joseph Plewa; Evan Tanner; Daniel M. Mueth; David G. Grier

2004-01-01

246

Imaging single carbon nanotubes with thermal radiation  

NASA Astrophysics Data System (ADS)

We have constructed tiny light bulbs, visible to the naked eye, using individual carbon nanotubes as filaments. A nanotube is suspended over a hole in a solid silicon substrate, and is heated to incandescence with electrical current. Diffraction-limited optical microscopy identifies the nanotube position and orientation, and allows direct comparison with high-resolution transmission electron micrographs of the same nanotube. Our current progress toward quantitative pyrometry will be described.

Fan, Yuwei; Singer, Scott; Bergstrom, Raymond; Regan, B. C.

2009-03-01

247

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

248

Polyethylene multiwalled carbon nanotube composites  

Microsoft Academic Search

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

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

2005-01-01

249

Carbon nanotube based battery architecture  

NASA Astrophysics Data System (ADS)

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

Kiebele, A.; Gruner, G.

2007-10-01

250

Engineering Carbon Nanotubes and Nanotube Circuits Using Electrical Breakdown  

NASA Astrophysics Data System (ADS)

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

Collins, Philip G.; Arnold, Michael S.; Avouris, Phaedon

2001-04-01

251

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

252

Theory of carbon nanotube growth  

NASA Astrophysics Data System (ADS)

The kinetics of carbon nanotube growth under arc discharge conditions were investigated over different length and time scales using complementary numerical techniques. Relaxation by ab initio molecular dynamics (Car-Parrinello method) shows that large electric fields present at the tube tips are not the critical factor responsible for the open-ended growth observed experimentally. Classical molecular-dynamics simulations using realistic many-body carbon-carbon potentials show that wide tubes that are initially open can continue to grow straight and maintain an all-hexagonal structure. However, tubes narrower than a critical diameter, estimated to be about ~3 nm, readily nucleate curved, pentagonal structures that lead to tube closure with further addition of atoms. Very narrow tubes can be grown, however, if a small metal particle prevents tube closure. This effect was simulated explicitly by kinetic Monte Carlo methods. Monte Carlo simulations were also used to study nanotube growth over longer time scales. The resulting structures are in agreement with the above growth scenario, and provide an estimate for the lowest tube tip temperature necessary for the growth of nanotubes.

Maiti, A.; Brabec, C. J.; Roland, C.; Bernholc, J.

1995-11-01

253

Stability of magnetic nanoparticles inside ferromagnetic nanotubes  

NASA Astrophysics Data System (ADS)

During the last years great attention has been given to the encapsulation of magnetic nanoparticles. In this work we investigated the stability of small magnetic particles inside magnetic nanotubes. Multisegmented geometries were tested in order to optimize the stability of the particle inside the nanotubes. Our results evidenced that multisegmented nanotubes are more efficient to entrap the particles at temperatures up to hundreds of kelvins.

Neumann, R. F.; Bahiana, M.; Escrig, J.; Allende, S.; Nielsch, K.; Altbir, D.

2011-01-01

254

Double-Wall Carbon Nanotubes  

Microsoft Academic Search

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

Rudolf Pfeiffer; Thomas Pichler; Yoong Kim; Hans Kuzmany

255

Lipid Bilayers Covalently Anchored to Carbon Nanotubes  

PubMed Central

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

Dayani, Yasaman; Malmstadt, Noah

2012-01-01

256

Multifunctional carbon-nanotube cellular endoscopes.  

PubMed

Glass micropipettes, atomic force microscope tips and nanoneedles can be used to interrogate cells, but these devices either have conical geometries that can damage cells during penetration or are incapable of continuous fluid handling. Here, we report a carbon-nanotube-based endoscope for interrogating cells, transporting fluids and performing optical and electrochemical diagnostics at the single organelle level. The endoscope, which is made by placing a multiwalled carbon nanotube (length, 50-60 µm) at the tip of a glass pipette, can probe the intracellular environment with a spatial resolution of ?100 nm and can also access organelles without disrupting the cell. When the nanotube is filled with magnetic nanoparticles, the endoscope can be remotely manoeuvered to transport nanoparticles and attolitre volumes of fluids to and from precise locations. Because they are mounted on conventional glass micropipettes, the endoscopes readily fit standard instruments, creating a broad range of opportunities for minimally invasive intracellular probing, drug delivery and single-cell surgery. PMID:21151109

Singhal, Riju; Orynbayeva, Zulfiya; Kalyana Sundaram, Ramalingam Venkat; Niu, Jun Jie; Bhattacharyya, Sayan; Vitol, Elina A; Schrlau, Michael G; Papazoglou, Elisabeth S; Friedman, Gary; Gogotsi, Yury

2010-12-12

257

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

Microsoft Academic Search

An in situ polymerization process was used to prepare poly (methyl methacrylate) (PMMA)-functionalized carboxyl multi-walled carbon nanotubes using carboxylate carbon nanotubes and methyl methacrylate as reactants and benzoyl peroxide as an initiator agent. The functionalized multi-walled carbon nanotubes were characterized using transmission electron microscope, scanning electron microscope, nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis and Raman. The results

Qing-Jie Meng; Xing-Xiang Zhang; Shi-He Bai; Xue-Chen Wang

2007-01-01

258

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 0.075-0.200µgKg(-1) respectively. The calibration curves were linear (r(2)?0.988) over the concentration ranges from 0.100µgKg(-1) to 250µgKg(-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 0.931µgKg(-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

2013-07-09

259

A Tunable Carbon Nanotube Oscillator  

NASA Astrophysics Data System (ADS)

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

Sazonova, Vera

2005-03-01

260

Neat macroscopic membranes of aligned carbon nanotubes  

NASA Astrophysics Data System (ADS)

Thick macroscopic membranes of magnetically aligned single-wall carbon nanotubes (SWNT) have been produced via high pressure filtration of aqueous surfactant-suspended SWNT in a magnetic field, resulting in membrane thicknesses of 10 ?m and surface areas of 125 cm2. Field strengths of 7 and 25 T were used. Polarized Raman spectroscopy shows an anisotropy of (2.5+/-0.5), indicating good alignment. A similar degree of alignment was seen at both intensities of magnetic field. Furthermore, the degree of alignment is comparable to that achieved in previous work that produced smaller and thinner membranes at 25 T. The membranes also exhibit uniform anisotropy across their surface and throughout their thickness.

Casavant, M. J.; Walters, D. A.; Schmidt, J. J.; Smalley, R. E.

2003-02-01

261

Carbon nanotube based high resolution holograms.  

PubMed

Carbon nanotubes are used as the smallest possible scattering element for diffracting light in a highly controlled manner to produce a 2D image. An array of carbon nanotubes is elegantly patterned to produce a high resolution hologram. In response to incident light on the hologram, a high contrast and wide field of view CAMBRIDGE image is produced. PMID:22936595

Butt, Haider; Montelongo, Yunuen; Butler, Tim; Rajesekharan, Ranjith; Dai, Qing; Shiva-Reddy, Sai G; Wilkinson, Timothy D; Amaratunga, Gehan A J

2012-08-31

262

Catalytic Routes Towards Single Wall Carbon Nanotubes  

Microsoft Academic Search

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

Emmanuel Lamouroux; Philippe Serp; Philippe Kalck

2007-01-01

263

High Performance Multifunctional Carbon Nanotube Fibers  

Microsoft Academic Search

Exploiting the extraordinary properties of carbon nanotubes has remained somewhat elusive due to the inability to process the as produced insoluble soot into functional macroscopic assemblies. To this end we have developed a simple but effective method to produce continuous, homogeneous fibers containing carbon nanotubes having as-spun mechanical properties that compare very favorably to recognized synthetic and natural \\

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

2003-01-01

264

Ophthalmologial Applications of Carbon Nanotube Nanotechology.  

National Technical Information Service (NTIS)

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

D. Loftus

2002-01-01

265

Carbon nanotubes in hydrogen fuel cells  

Microsoft Academic Search

Carbon nanotubes possess exceptional mechanical and electrical properties such as high tensile strength, great resilience, high thermal and electrical conductivity, high specific surface area, and high temperature stability. The coexistence of these desirable properties in one material makes carbon nanotubes a fascinating candidate for incorporation into a fuel cell to improve its performance and decrease the thickness of the fuel

Jason Ming-Young Tang

2007-01-01

266

Faster and Smaller with Carbon Nanotubes?  

Microsoft Academic Search

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

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

267

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

PubMed

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

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

2012-01-19

268

Supported Lipid Bilayer/Carbon Nanotube Hybrids  

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

269

Electroluminescence Properties of Carbon Nanotube Network Transistors  

NASA Astrophysics Data System (ADS)

Carbon nanotubes network transistors (CNNT) open a promising route for the integration of nanotubes in electronics for that they circumvent major issues related to their fabrication. [1] They also reduce device-to-device discrepancies because they combine the properties of an ensemble of nanotube species. Here, we investigated the optoelectronic properties of the CNNT fabricated from different nanotube sources and found bright electroluminescent (EL) emission. The EL is specific to the nanotube source and can be linked using absorption spectra to their diameter distribution. (1) E.S. Snow, P.M. Campbell, M.G. Ancona, Appl. Phys. Lett., 2005, 86, 033105.

St-Antoine, Benoit; Adam, Elyse; Aguirre, Carla; Menard, David; Martel, Richard

2007-03-01

270

Induced and intrinsic superconductivity in carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

271

Carboxymethylcellulose/single walled carbon nanotube complexes.  

PubMed

In this work, Carboxymethylcellulose/single walled carbon nanotube hybrids are prepared. Our goal is to use the non-covalent association of an anionic polysaccharide and single walled carbon nanotubes to prepare a biocompatible complex which preserves the intrinsic properties of the nanotubes. The hybrids are characterized by Raman scattering, Emission spectroscopy and Atomic Force Microscopy. A comparison is made with sodium dodecyl benzene sulfonate dispersed nanotubes. We show that carboxymethylcellulose forms an apparently non-helicoidal superstructure with carbon nanotubes which leads to their individualization. Emission and Raman spectroscopies suggest that the interaction occurs preferentially with semiconducting nanotubes. Further sugar chemistry may open different functionalization opportunities that will contribute to the design of biosensors and open this field of applications. PMID:19908512

Riou, I; Bertoncini, P; Bizot, H; Mevellec, J Y; Buléon, A; Chauvet, O

2009-10-01

272

Geckolike high shear strength by carbon nanotube fiber adhesives  

Microsoft Academic Search

Carbon nanotube adhesives can adhere strongly to surfaces as a gecko does. The number of carbon nanotube layers is an important determinant of the contact area for adhesion. Balancing the catalyst ratio and buffer layer used for chemical vapor deposition processing controls the number of carbon nanotube layers and their distribution. The features of carbon nanotubes determine the shear strength

Y. Maeno; Y. Nakayama

2009-01-01

273

Carbon nanotubes coated by carbon nanoparticles of turbostratic stacked graphenes  

Microsoft Academic Search

Carbon nanotubes (CNTs) decorated by a high density of carbon nanoparticles of turbostratic graphene stacks have been fabricated by low energy hydrocarbon ion deposition at 700°C. Transmission and scanning electron microscopy show that the carbon particles of turbostratic graphene stacks extend from the nanotube surface. The diameter of CNTs decreases with the increasing percentage of hydrogen in the gas phase.

Qintao Li; Zhichun Ni; Jinlong Gong; Dezhang Zhu; Zhiyuan Zhu

2008-01-01

274

Anisotropy of the optical conductivity and infrared-active optical phonons in magnetically aligned single wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

We investigated effective dielectric function of the samples with aligned single wall carbon nanotubes (SWNT) in the far infrared frequency range between 50 and 4000 cm-1. A combination of the Fourier-transform infrared (FT-IR) ellipsometry and synchrotron radiation of the U10A and U2B beamlines at the National Synchrotron Light Source, Brookhaven National Laboratory, has been utilized. Anisotropy of the both real and imaginary parts of the effective dielectric function of the SWNT has been observed. In the far infrared spectral range, the optical conductivity along the direction of the nanotubes is about 5 times higher than that for the perpendicular direction. The investigated samples revealed metallic behavior at room temperature, while at low temperatures the samples became more insulating. A formation of an infrared optical gap in the optical conductivity in the region between 200 and 300 cm-1 have been detected at low temperature. Spectral features related to the IR-active optical phonons have been measured at about 1630 cm-1.

Sirenko, A. A.; Eklund, P. C.; Bernhard, C.; Holden, Todd; Homes, C.; Marinkovic, N.; Walters, D. A.; Casavant, M. J.; Schmidt, J.; Smalley, R. E.

2001-03-01

275

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

276

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

277

Electronic specific heat of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The electronic structure of single-walled carbon nanotubes is calculated by the tight-binding model. A single-walled carbon nanotube could drastically change from a metal to a semiconductor or vice versa during the variation of magnetic flux. The low-temperature electronic specific heat thus exhibits the rich temperature and magnetic-flux dependence. There are four kinds of temperature dependence in the presence of the magnetic field, mainly due to the interaction between spin and magnetic field. Moreover, the magnetic-flux-dependent specific heat exhibits the pronounced oscillatory behavior including asymmetric two-peak structures. These structures strongly depend on the characteristics of the subbands nearest the Fermi level.

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

1996-07-01

278

Electronic structure of atomically resolved carbon nanotubes  

Microsoft Academic Search

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,

Liesbeth Venema; Andrew G. Rinzler; Richard E. Smalley; Cees Dekker

1998-01-01

279

Nanotube Content in Arc Generated Carbon Powder  

Microsoft Academic Search

Summary.  ?A novel experimental technique for the separation of nanotubes from other unwanted carbon species in arc generated carbon\\u000a soot is described. A conjugated polymer was used to bind to nanotubes in solution. The resultant hybrid was soluble, whereas\\u000a extraneous carbon material formed a sediment at the bottom of the sample bottle. The process was monitored using electron\\u000a paramagnetic resonance (EPR)

Jonathan N. Coleman; Diarmuid F. O’Brien; Brendan McCarthy; Robert C. Barklie; Werner J. Blau

2001-01-01

280

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

281

ANALYSIS OF FLUID IN HYDROTHERMAL CARBON NANOTUBES  

Microsoft Academic Search

Understanding of the interaction of water-based liquids with carbon at the nanoscale is of great importance for exploring the potential of carbon nanotubes in nanofluidic applications. Using hydrothermal synthesis, hydrophilic multiwall carbon nanotubes filled with an aqueous fluid have been produced. These closed tubes were synthesized from an equilibrated C-H-O fluid, in the presence of Ni catalyst, at 730- 800°C

Y. Gogotsi; N. Naguib; H. Ye; A. G. Yazicioglu; C. M. Megaridis

2002-01-01

282

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

PubMed

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

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

2012-12-13

283

Low- Temperature Magneto-conductance In Carbon Nano-tubes  

NASA Astrophysics Data System (ADS)

Angular dependent magneto-resistance (MR) has been studied in Multi- walled carbon nano-tubes (MWNTs). In case of thin MWNTs, the flux cancelation has been observed in the low temperature MR. Based on the theoretical studies on the scattering behaviors in the carbon nano-tube (CNT) and flux cancelation in one dimensional transport in CNT, we can analyze an intrinsic carrier scattering based on our MR result of the angular dependence between the angle of thin MWNT axis in parallel and perpendicular directions to the magnetic fields. Also, we can discuss on the positive MR appeared in the perpendicular field direction into the thin MWNT axis.

Ochiai, Yuichi; Seino, Atsuro; Kida, Michio; Aoki, Nobuyuki; Nakanishi, Takeshi; Bird, Jonathan

2011-03-01

284

Gas molecule adsorption in carbon nanotubes and nanotube bundles  

Microsoft Academic Search

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

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

2002-01-01

285

The electrical conduction variation in stained carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

286

Enzymatic degradation of multiwalled carbon nanotubes.  

PubMed

Because of their unique properties, carbon nanotubes and, in particular, multiwalled carbon nanotubes (MWNTs) have been used for the development of advanced composite and catalyst materials. Despite their growing commercial applications and increased production, the potential environmental and toxicological impacts of MWNTs are not fully understood; however, many reports suggest that they may be toxic. Therefore, a need exists to develop protocols for effective and safe degradation of MWNTs. In this article, we investigated the effect of chemical functionalization of MWNTs on their enzymatic degradation with horseradish peroxidase (HRP) and hydrogen peroxide (H(2)O(2)). We investigated HRP/H(2)O(2) degradation of purified, oxidized, and nitrogen-doped MWNTs and proposed a layer-by-layer degradation mechanism of nanotubes facilitated by side wall defects. These results provide a better understanding of the interaction between HRP and carbon nanotubes and suggest an eco-friendly way of mitigating the environmental impact of nanotubes. PMID:21348486

Zhao, Yong; Allen, Brett L; Star, Alexander

2011-02-24

287

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

288

Carbon Nanotube Films for Hydrogen Sensing.  

National Technical Information Service (NTIS)

A multi-layer H.sub.2 sensor includes a carbon nanotube layer, and a ultra-thin metal or metal alloy layer in contact with the nanotube layer. The ultra-thin metal or metal alloy layer is preferably from 10 to 50 angstroms thick. An electrical resistance ...

A. G. Rinzler B. S. Kang F. Ren H. T. Wang J. A. Sippel-Oakley

2005-01-01

289

Electronic Structure of Deformed Carbon Nanotubes  

Microsoft Academic Search

Electronic structure of deformed carbon nanotubes varies widely depending on their chirality and deformation mode. We present a framework to analyze these variations by quantifying the dispersion relation and density of states. The theory is based on the Hückel tight-binding model and confirmed by four orbital tight-binding simulations of nanotubes under stretching, compression, torsion, and bending. It unriddles and unifies

Liu Yang; Jie Han

2000-01-01

290

Signal Integrity of Carbon Nanotube Bundles  

Microsoft Academic Search

Simulation models are proposed to predict the transmission performances and the signal integrity of single-wall carbon nanotube (SWCNT) bundles in the frequency and time domain. The multiconductor transmission line approach is used for the computation of the common mode responses of bundles made by a different number of conductive nanotubes in the frequency range up to 10 GHz. The eye-diagram

M. D'Amore; M. S. Sarto; A. Tamburrano

2007-01-01

291

Carbon nanotube filaments in household light bulbs  

Microsoft Academic Search

Household light bulbs made from macroscopic single-walled and double-walled carbon nanotube filaments were fabricated and tested. The nanotube bulbs are found to possess several interesting features when compared to a conventional tungsten filament in safelight (36 V, 40 W), such as lower threshold voltage for light emission and higher brightness at high voltages. Electrically induced excited peaks at 407, 417,

Jinquan Wei; Hongwei Zhu; Dehai Wu; Bingqing Wei

2004-01-01

292

End cap nucleation of carbon nanotubes  

Microsoft Academic Search

An easily applied graphical approach for facilitating precise tailoring during computational construction of model uncapped or capped single-wall nanotubes or fullerenes is delineated and utilized in this paper. The main enabling concepts are the commonly suggested growth mechanisms for single- and multi-walled carbon nanotubes mediated by end cap structures. The construction protocol described herein can be used to rapidly create

S. L. Lair; W. C. Herndon; L. E. Murr; S. A. Quinones

2006-01-01

293

In vitro studies of carbon nanotubes biocompatibility  

Microsoft Academic Search

Cellular tests have been applied to study the biocompatibility of high purity multiwalled carbon nanotubes (MWNTs). The viability of fibroblasts, osteoblasts and osteocalcin concentrations in osteoblasts cultures in the presence of nanotubes has been examined, as well as the degree of cells stimulation, based on the amount of released collagen type I, IL-6 and oxygen free radicals. The high level

J. Ch?opek; B. Czajkowska; B. Szaraniec; E. Frackowiak; K. Szostak; F. Béguin

2006-01-01

294

Carbon Nanotube Based Composites A Review  

Microsoft Academic Search

Carbon nanofibers and nanotubes are promising to revolutionise several fields in material science and are a major component of nanotechnology. Further market development will depend on material availability at reasonable prices. Nanotubes have a wide range of unexplored potential applications in various technological areas such as aerospace, energy, automobile, medicine, or chemical industry, in which they can be used as

Rupesh Khare; Suryasarathi Bose

295

Phonon runaway in carbon nanotube quantum dots  

Microsoft Academic Search

We explore electronic transport in a nanotube quantum dot strongly coupled with vibrations and weakly with leads and the thermal environment. We show that the recent observation of anomalous conductance signatures in single-walled carbon nanotube quantum dots [B. J. LeRoy , Nature (London) 395, 371 (2004) and B. J. LeRoy , Phys. Rev. B 72, 075413 (2005)] can be understood

L. Siddiqui; A. W. Ghosh; S. Datta

2007-01-01

296

Infrared transparent carbon nanotube thin films  

Microsoft Academic Search

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 Ω\\/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

Liangbing Hu; David S. Hecht

2009-01-01

297

Infrared transparent carbon nanotube thin films  

Microsoft Academic Search

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 Omega\\/sq show outstanding transmittance in the infrared range up to at least 22 mum, with an average transmittance greater than 90% over this range. The infrared properties of various materials were

Liangbing Hu; David S. Hecht; George Grüner

2009-01-01

298

Carbon nanotubes: Synthesis, characterization, and applications  

Microsoft Academic Search

Carbon nanotubes (CNTs) possess exceptional material properties, making them desirable for use in a variety of applications. In this work, CNTs were grown using two distinct catalytic chemical vapor deposition (CVD) procedures, floating catalyst CVD and thermal CVD, which differed in the method of catalyst introduction. Reaction conditions were optimized to synthesize nanotubes with desired characteristics, and the effects of

Christian Peter Deck

2009-01-01

299

Carbon nanotube growth by PECVD: a review  

Microsoft Academic Search

Carbon nanotubes (CNTs), due to their unique electronic and extraordinary mechanical properties, have been receiving much attention for a wide variety of applications. Recently, plasma enhanced chemical vapour deposition (PECVD) has emerged as a key growth technique to produce vertically-aligned nanotubes. This paper reviews various plasma sources currently used in CNT growth, catalyst preparation and growth results. Since the technology

M. Meyyappan; Lance Delzeit; Alan Cassell; David Hash

2003-01-01

300

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

301

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

PubMed

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

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

2011-12-28

302

Highly oriented carbon nanotube papers made of aligned carbon nanotubes.  

PubMed

Paper-like carbon nanotube (CNT) materials have many important applications such as in catalysts, in filtration, actuators, capacitor or battery electrodes, and so on. Up to now, the most popular way of preparing buckypapers has involved the procedures of dispersion and filtration of a suspension of CNTs. In this work, we present a simple and effective macroscopic manipulation of aligned CNT arrays called 'domino pushing' in the preparation of the aligned thick buckypapers with large areas. This simple method can efficiently ensure that most of the CNTs are well aligned tightly in the buckypaper. The initial measurements indicate that these buckypapers have better performance on thermal and electrical conductance. These buckypapers with controllable structure also have many potential applications, including supercapacitor electrodes. PMID:21817646

Wang, Ding; Song, Pengcheng; Liu, Changhong; Wu, Wei; Fan, Shoushan

2008-01-31

303

Dissymmetric carbon nanotubes by bipolar electrochemistry.  

PubMed

Short carbon nanotubes have been modified selectively on one end with metal using a bulk technique based on bipolar electrochemistry. A stabilized suspension of nanotubes is introduced in a capillary containing an aqueous metal salt solution, and a high electric field is applied to orientate and polarize the individual tubes. During their transport through the capillary under sufficient polarization (30 kV), each nanotube is the site of water oxidation on one end and the site of metal ion reduction on the other end with the size of the formed metal cluster being proportional to the potential drop along the nanotube. PMID:18189438

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

2008-01-12

304

Electrical conductivity of individual carbon nanotubes  

NASA Astrophysics Data System (ADS)

THE interest in carbon nanotubes has been greatly stimulated by theoretical predictions that their electronic properties are strongly modulated by small structural variations1-8. In particular, the diameter and the helicity of carbon atoms in the nanotube shell are believed to determine whether the nanotube is metallic or a semiconductor. Because of the enormous technical challenge of making measurements on individual nanotubes, however, experimental studies have been limited mainly to bulk measurements9, which indicate only that a fraction of the nanotubes are metallic or narrow-band semiconductors10. Recently, measurements of the magneto-conductance of a single multi-shell nanotube in a two-probe configuration showed that the transport is characterized by disorder and localization phenomena11. To avoid possible ambiguities due to poor sample contacts, four-probe measurements are needed. Here we report four-probe measurements on single nanotubes made by lithographic deposition of tungsten leads across the tubes. We find that each multi-shell nanotube has unique conductivity properties. Both metallic and non-metallic behaviour are observed, as well as abrupt jumps in conductivity as the temperature is varied. The differences between the electrical properties of different nanotubes are far greater than expected. Our results suggest that differences in geometry play a profound part in determining the electronic behaviour.

Ebbesen, T. W.; Lezec, H. J.; Hiura, H.; Bennett, J. W.; Ghaemi, H. F.; Thio, T.

1996-07-01

305

Functionalization of carbon nanotubes with silver clusters  

NASA Astrophysics Data System (ADS)

In this paper, an advanced method of one-step functionalization of single and multi walled carbon nanotubes (SWCNTs and MWCNTs) using ?-irradiation was described. Two synthesis procedures, related with different reduction species, were employed. For the first time, poly(vinyl alcohol) PVA is successfully utilized as a source to reduce silver (Ag) metal ions without having any additional reducing agents to obtain Ag nanoparticles on CNTs. The decoration of carbon nanotubes with Ag nanoparticles takes place through anchoring of (PVA) on nanotube's surface. Optical properties of as-prepared samples and mechanism responsible for the functionalization of carbon nanotubes were investigated using UV-vis and FTIR spectroscopy, respectively. Decorated carbon nanotubes were visualized using microscopic techniques: transmission electron microscopy and scanning tunneling microscopy. Also, the presence of Ag on the nanotubes was confirmed using energy dispersive X-ray spectroscopy. This simple and effective method of making a carbon nanotube type of composites is of interest not only for an application in various areas of technology and biology, but for investigation of the potential of radiation technology for nanoengineering of materials.

Cveticanin, Jelena; Krkljes, Aleksandra; Kacarevic-Popovic, Zorica; Mitric, Miodrag; Rakocevic, Zlatko; Trpkov, Djordje; Neskovic, Olivera

2010-09-01

306

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

307

Aligned multiwalled carbon nanotube membranes.  

PubMed

An array of aligned carbon nanotubes (CNTs) was incorporated across a polymer film to form a well-ordered nanoporous membrane structure. This membrane structure was confirmed by electron microscopy, anisotropic electrical conductivity, gas flow, and ionic transport studies. The measured nitrogen permeance was consistent with the flux calculated by Knudsen diffusion through nanometer-scale tubes of the observed microstructure. Data on Ru(NH3)6(3+) transport across the membrane in aqueous solution also indicated transport through aligned CNT cores of the observed microstructure. The lengths of the nanotubes within the polymer film were reduced by selective electrochemical oxidation, allowing for tunable pore lengths. Oxidative trimming processes resulted in carboxylate end groups that were readily functionalized at the entrance to each CNT inner core. Membranes with CNT tips that were functionalized with biotin showed a reduction in Ru(NH3)6(3+) flux by a factor of 15 when bound with streptavidin, thereby demonstrating the ability to gate molecular transport through CNT cores for potential applications in chemical separations and sensing. PMID:14645855

Hinds, Bruce J; Chopra, Nitin; Rantell, Terry; Andrews, Rodney; Gavalas, Vasilis; Bachas, Leonidas G

2003-11-26

308

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

309

Carbon Nanotube Schottky Barrier Photovoltaic Cell.  

National Technical Information Service (NTIS)

Carbon nanotube Schottky barrier photovoltaic cells and methods and apparatus for making the cells are provided. The photovoltaic cells include at least one contact made from a first contact material, at least one contact made from a second contact materi...

M. A. Eriksson M. G. Lagally M. S. Marcus T. R. Narkis

2005-01-01

310

Synthesis of Amide Functionalized Carbon Nanotubes.  

National Technical Information Service (NTIS)

A covalent, amide-bond interconnection between functionalized single- wall carbon nanotubes (SWNTs) is reported. SWNTs covalently connected via an amide bond were prepared by coupling the carboxylic acid group from one SWNT with the amine group on a diffe...

C. Whitaker I. C. Uber J. R. Heckert

2007-01-01

311

Novel Synthesis of Branched Carbon Nanotubes.  

National Technical Information Service (NTIS)

The present invention discloses a relatively simple CVD method for forming branched carbon nanotubes. In general, the method includes adding a dopant to the precursor materials. The dopant can be a material that has a thermodynamically more favorable carb...

A. M. Rao N. W. Gothard J. B. Gaillard

2004-01-01

312

Spinning Carbon Nanotubes Spawns New Wireless Applications  

NSDL National Science Digital Library

This news article from the University of Cincinnati describes how long carbon nanotubes grown in its labs are spun into threads, and how these threads can function as an antenna. Photographs and several videos are included.

2009-05-16

313

Manipulating Local Electronic Properties of Carbon Nanotubes.  

National Technical Information Service (NTIS)

Carbon nanotubes have many emerging technological uses, from strengthening lightweight composite materials to reducing voltage requirements in field-emission displays. Companies such as IBM and Intel have substantial research efforts aimed at the more com...

D. Goldhaber-Gordon

2008-01-01

314

Manipulating Local Electronic Properties of Carbon Nanotubes.  

National Technical Information Service (NTIS)

Carbon nanotubes have many emerging technological uses, from strengthening lightweight composite materials to reducing voltage requirements in field-emission displays. Companies such as IBM and Intel have substantial research efforts aimed at the more com...

D. Goldhaber-Gordon

2011-01-01

315

Fabrication of porous carbon nanotube network.  

PubMed

We used the spin-coating method combined with ultrasonic atomization as a continuous, one-step process to generate a two-dimensional honeycomb network that was constructed from pure multi-walled carbon nanotubes. PMID:18997975

Su, Jun-Wei; Fu, Shu-Juan; Gwo, Shangjr; Lin, Kuan-Jiuh; Lin, Kuna-Jiuh

2008-10-08

316

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

317

Carbon nanotube polymer composition and devices  

SciTech Connect

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

318

Length scaling of carbon nanotube transistors.  

PubMed

Carbon nanotube field-effect transistors are strong candidates in replacing or supplementing silicon technology. Although theoretical studies have projected that nanotube transistors will perform well at nanoscale device dimensions, most experimental studies have been carried out on devices that are about ten times larger than current silicon transistors. Here, we show that nanotube transistors maintain their performance as their channel length is scaled from 3 µm to 15 nm, with an absence of so-called short-channel effects. The 15-nm device has the shortest channel length and highest room-temperature conductance (0.7G?) and transconductance (40 µS) of any nanotube transistor reported to date. We also show the first experimental evidence that nanotube device performance depends significantly on contact length, in contrast to some previous reports. Data for both channel and contact length scaling were gathered by constructing multiple devices on a single carbon nanotube. Finally, we demonstrate the performance of a nanotube transistor with channel and contact lengths of 20 nm, an on-current of 10 µA, an on/off current ratio of 1 x 10?, and peak transconductance of 20 µS. These results provide an experimental forecast for carbon nanotube device performance at dimensions suitable for future transistor technology nodes. PMID:21102468

Franklin, Aaron D; Chen, Zhihong

2010-11-21

319

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

320

Functionalized carbon nanotubes and device applications  

Microsoft Academic Search

Carbon nanotubes, in which the two-dimensional hexagonal lattice of graphene is transformed into a quasi-one-dimensional lattice by conserving the local bond arrangement, provide several structural parameters for engineering novel physical properties suitable for ultimate miniaturization. Recent interest in nanoscience and nanotechnology has driven a tremendous research activity in carbon nanotubes, which has dealt with a variety of problems and produced

S Ciraci; S Dag; T Yildirim; R T Senger

2004-01-01

321

Electrospray deposition of carbon nanotubes in vacuum  

Microsoft Academic Search

Here we report on a novel and effective technique for the deposition of carbon nanotubes onto surfaces in vacuum directly from a liquid suspension. The technique, based on in-vacuum electrospray ionization, has the potential to bridge the gap between high resolution techniques requiring ultra-high vacuum conditions, and non-volatile molecules and nanostructures such as carbon nanotubes. Atomic force microscopy of double-walled

James N O’Shea; John B Taylor; Janine C Swarbrick; Graziano Magnano; Louise C Mayor; Karina Schulte

2007-01-01

322

Flow of Aqueous Solutions in Carbon Nanotubes  

Microsoft Academic Search

\\u000a We conduct simulations of water flowing inside carbon nanotubes using non-equilibrium molecular dynamics simulations. A new\\u000a adaptive forcing scheme is proposed to enforce a mean center of mass velocity. This scheme is compared to the non-adaptive,\\u000a constant body\\/gravity force for the flow of methane in a carbon nanotube. The two schemes produce similar streaming velocity\\u000a profiles and practically identical slip

S. C. Kassinos; J. H. Walther; E. Kotsalis; P. Koumoutsakos

323

Macroscopic Neat Single Wall Carbon Nanotube Fibers  

Microsoft Academic Search

Measured and predicted properties of single wall carbon nanotubes (SWNT) suggest that neat SWNT fibers will exhibit a variety of exceptional properties. Macroscopic fibers composed entirely of single wall carbon nanotubes (SWNT) have been successfully created. HiPco SWNT were dispersed in strong acids at high concentrations (4-10wt%) and extruded using conventional fiber spinning methods. The fibers exhibit remarkable internal alignment,

Lars M. Ericson; Sivarajan Ramesh; Rajesh Saini; Virginia A. Davis; Carter Kittrell; Michael J. Casavant; Matteo Pasquali; Robert H. Hauge; Richard E. Smalley; Alan Dalton; Ray H. Baughman; John E. Fischer

2002-01-01

324

Channeling of protons through carbon nanotubes  

Microsoft Academic Search

We investigate how dynamic polarization of carbon valence electrons influences both the angular and spatial distributions of protons channeled in a (11, 9) single-wall carbon nanotube placed in vacuum and in different dielectric media. Proton speeds between 3 and 10 a.u., corresponding to energies of 0.223 and 2.49 MeV, are chosen with the nanotube length varied between 0.1 and 1

D. Borka; D. J. Mowbray; Z. L. Miskovic; S. Petrovic; N. Neskovic

2008-01-01

325

Ultrasonic Spraying Thin Films of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes have many interesting and useful properties, especially in terms of strength and electrical conductivity. However, they can be hard to work with because they are held together in bundles by strong Van der Waals forces. Much work has been performed in the ultrasonic spraying of liquid suspensions of single and multi-wall carbon nanotubes. The resulting thin films have a variety of applications, including electron transport in thin film photovoltaics.

Willey, Anthony; Davis, Robert; Vanfleet, Richard; Balls, Amy; Abbott, Jonathan

2011-10-01

326

Electromechanical instability in suspended carbon nanotubes.  

PubMed

We have theoretically investigated electromechanical properties of freely suspended carbon nanotubes when a current is injected into the tubes using a scanning tunneling microscope. We show that a shuttle-like electromechanical instability can occur if the bias voltage exceeds a dissipation-dependent threshold value. An instability results in large amplitude vibrations of the carbon nanotube bending mode, which modify the current-voltage characteristics of the system. PMID:15943462

Jonsson, L Magnus; Gorelik, Leonid Y; Shekhter, Robert I; Jonson, Mats

2005-06-01

327

Hydrogen storage in boron substituted carbon nanotubes  

Microsoft Academic Search

Template assisted synthesis of boron substituted carbon nanotubes was carried out by the carbonization of hydroborane polymer in alumina membrane template. The nanotubes were characterized by electron microscopic analysis, FT-Raman, FT-IR, XRD, X-ray photoelectron spectroscopy (XPS) and 13C &11B MAS NMR techniques. The presence of boron in different chemical environment has been visualized by XPS and 11B MAS NMR. The

M. Sankaran; B. Viswanathan

2007-01-01

328

Nanoelectronics in a multiwall carbon nanotube  

Microsoft Academic Search

Multiwall carbon nanotubes (MWNTs) are one of natural nano-size bricks. The MWNTs are conductive narrow wires, and would be useful materials for a component of nano-electronics. By building up the MWNT bricks, nano-scale device structures, which cannot be fabricated from three dimensional bulk materials, can be constructed. For the application of carbon nanotubes to molecular electronic devices, it is very

K. Tsukagoshi; A. Kanda; N. Yoneya; E. Watanabe; Y. Ootuka; Y. Aoyagi

2001-01-01

329

Exploring the Immunotoxicity of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Mass production of carbon nanotubes (CNTs) and their applications in nanomedicine lead to the increased exposure risk of nanomaterials to human beings. Although reports on toxicity of nanomaterials are rapidly growing, there is still a lack of knowledge on the potential toxicity of such materials to immune systems. This article reviews some existing studies assessing carbon nanotubes’ toxicity to immune system and provides the potential mechanistic explanation.

Yu, Yanmei; Zhang, Qiu; Mu, Qingxin; Zhang, Bin; Yan, Bing

2008-08-01

330

Functionalized carbon nanotubes: biomedical applications.  

PubMed

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

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

2012-10-09

331

Bending Instabilities of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

This paper presents an investigation on the buckling behaviour of single-walled carbon nanotubes (NTs) under bending and unveils several aspects concerning the dependence of critical bending curvature on the NT length. The buckling results are obtained by means of non-linear shell finite element analyses using ABAQUS code. It is shown that eigenvalue analyses do not give a correct prediction of the critical curvature of NTs under bending. Conversely, incremental-iterative non-linear analyses provide a better approximation to the molecular dynamics results due to the progressive ovalization of the NT cross-section under bending. For short NTs, the limit curvature drops with the increasing length mostly due to the decreasing influence of end effects. For moderate to long tubes, the limit curvature remains practically constant and independent on the tube length. An approximate formula based on the Brazier expression is proposed to predict the limit curvature.

Silvestre, N.; Camotim, D.

332

Photonics based on carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

333

Photonics based on carbon nanotubes  

PubMed Central

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

2013-01-01

334

Method for nano-pumping using carbon nanotubes  

SciTech Connect

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

335

Thermogravimetric analysis of carbon nanotubes and nanoparticles  

SciTech Connect

The oxidation of carbon nanotubes and nanoparticles has been studied by thermogravimetric analysis (TGA) in air. The maximum rate of weight loss took place at 695[degrees]C at a heating rate of 1[degrees]C/min. This result shows that the nanotubes and nanoparticles are more resistant to oxidation than other forms of carbon diamond, soot, graphite, and C[sub 60] studied previously under identical conditions. The TGA of the nanotubes/nanoparticles in argon showed no weight change or detectable thermal transformation up to 1000[degrees]C. 18 refs., 1 fig.

Pang, L.S.K.; Saxby, J.D.; Chatfield, S.P. (CSIRO Division of Coal and Energy Technology, North Ryde, NSW (Australia))

1993-07-08

336

Immersing carbon nanotubes in cold atomic gases  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

337

Quantitative theory of diffraction by carbon nanotubes  

NASA Astrophysics Data System (ADS)

A quantitative theory of the kinematical diffraction of a plane wave by a carbon nanotube is developed. The formalism is based on the Cochran, Crick, and Vand theory of the diffraction by helical molecules. This leads to a closed-form expression of the diffracted amplitude produced by a single-wall tubule of arbitrary helicity, applicable to both X rays and high-energy electrons. The theory, which can be used to simulate the diffraction pattern of any multilayer nanotube, is illustrated on the case of a crystalline rope of carbon nanotubes.

Lambin, Ph.; Lucas, A. A.

1997-08-01

338

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

339

Inhaled carbon nanotubes reach the subpleural tissue in mice  

Microsoft Academic Search

Carbon nanotubes are shaped like fibres and can stimulate inflammation at the surface of the peritoneum when injected into the abdominal cavity of mice, raising concerns that inhaled nanotubes may cause pleural fibrosis and\\/or mesothelioma. Here, we show that multiwalled carbon nanotubes reach the subpleura in mice after a single inhalation exposure of 30 mg m?3 for 6 h. Nanotubes

Jessica P. Ryman-Rasmussen; Mark F. Cesta; Arnold R. Brody; Jeanette K. Shipley-Phillips; Jeffrey I. Everitt; Earl W. Tewksbury; Owen R. Moss; Brian A. Wong; Darol E. Dodd; Melvin E. Andersen; James C. Bonner

2009-01-01

340

Band Gap Fluorescence from Individual Single-Walled Carbon Nanotubes  

Microsoft Academic Search

Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes. We obtained individual nanotubes, each encased in a cylindrical micelle, by ultrasonically agitating an aqueous dispersion of raw single-walled carbon nanotubes in sodium dodecyl sulfate and then centrifuging to remove tube bundles, ropes, and residual catalyst. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions

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

2002-01-01

341

Diffusion of metal in a confined nanospace of carbon nanotubes induced by air oxidation.  

PubMed

Air oxidation can result in the motion of metal confined in carbon nanotubes (CNTs). This can also be utilized to tailor various hybrid nanostructures. By controllable air-oxidation, as-prepared metal@CNT nanorods (a) can be converted first to core-shell-void nanorods (b), then to metal/metal oxide@CNT nanotubes (c), and finally to mesoporous metal oxide nanotubes (d). The metal/metal oxide@CNT nanotubes and mesoporous metal oxide nanotubes are expected to find many applications, such as in lithium ion batteries, catalysis, magnetic drug delivery, and gas sensing. PMID:20684548

Zhou, Jisheng; Song, Huaihe; Chen, Xiaohong; Huo, Junping

2010-08-25

342

Properties of low-temperature grown carbon nanotubes  

Microsoft Academic Search

The growth of carbon nanotubes was investigated using a hot filament assisted CVD system. The silicon and glass substrates coated with catalyst were kept in a CVD furnace tube and the carbon nanotubes were grown by a hot filament assisted decomposition of methane (CH4). Argon (Ar) was used as carrier for carbon. It was found that carbon nanotubes could be

Kun Guo; Ahalapitiya H. Jayatissa

2007-01-01

343

Effect of purification treatment on adsorption characteristics of carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes are novel materials with porous-rich structures and superior adsorption characteristics. In this report, multi-walled carbon nanotubes with different diameter were synthesized by thermal chemical vapor deposition. Amorphous carbon particles were highly removed by thermal oxidation process. Microwave digestion acidic procedure was used to dissolve metal catalysts and open tip of carbon nanotubes. The opened-end multi-walled carbon nanotubes are

Mi Chen; Hung-Wei Yu; Jhih-Hong Chen; Horng-Show Koo

2007-01-01

344

Carbon nanotube reinforced polyacrylonitrile and poly(etherketone) fibers  

Microsoft Academic Search

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

Rahul Jain

2009-01-01

345

Fast readout of carbon nanotube mechanical resonators  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

346

Functionalization of vertically aligned carbon nanotubes  

PubMed Central

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

Snyders, Rony; Colomer, Jean-Francois

2013-01-01

347

Biocompatibility of iron filled carbon nanotubes in vitro.  

PubMed

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

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

2009-10-01

348

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

349

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

NASA Astrophysics Data System (ADS)

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

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

2009-09-01

350

Kondo effect of magnetic impurities on nanotubes  

NASA Astrophysics Data System (ADS)

The effect of magnetic impurities on the ballistic conductance of nanocontacts is, as suggested in the recent work, amenable to ab initio study [1]. Our method proceeds via a conventional density functional calculation of spin- and symmetry-dependent electron scattering phase shifts, followed by the subsequent numerical renormalization group solution of Anderson models—whose ingredients and parameters are chosen so as to reproduce these phase shifts. We apply this method to investigate the Kondo zero bias anomalies that would be caused in the ballistic conductance of perfect metallic (4,4) and (8,8) single wall carbon nanotubes, ideally connected to leads at the two ends, by externally adsorbed Co and Fe adatoms. The different spin and electronic structures of these impurities are predicted to lead to a variety of Kondo temperatures, generally well below 10 K, and to interference between channels leading to Fano-like conductance minima at zero bias.

Baruselli, P. P.; Smogunov, A.; Fabrizio, M.; Tosatti, E.

2012-03-01

351

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

352

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

353

Preparation, characterization, adsorption kinetics and thermodynamics of novel magnetic chitosan enwrapping nanosized ?-Fe 2O 3 and multi-walled carbon nanotubes with enhanced adsorption properties for methyl orange  

Microsoft Academic Search

A novel magnetic composite bioadsorbent composed of chitosan wrapping magnetic nanosized ?-Fe2O3 and multi-walled carbon nanotubes (m-CS\\/?-Fe2O3\\/MWCNTs) was prepared under relative mild conditions and was characterized. Adsorption of methyl orange (MO) onto m-CS\\/?-Fe2O3\\/MWCNTs was investigated with respect to pH, initial MO concentration, coexisting anions and temperature. Results of characterizations indicated that magnetic nanosized ?-Fe2O3 and MWCNTs have been wrapped by

H. Y. Zhu; R. Jiang; L. Xiao; G. M. Zeng

2010-01-01

354

Carbon Nanotube Templated Microfabrication of Porous Silicon-Carbon Materials  

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

355

Capacitance measurements of individual carbon nanotubes  

NASA Astrophysics Data System (ADS)

We present measurements of the capacitance of individual single walled carbon nanotubes. The nanotubes were grown from ethylene at 700^oC using evaporated iron nanoclusters as the catalyst. Electrical contacts and local top gates were patterned using optical lithography and liftoff. The top gate consists of a thin oxide film (˜15 nm, different oxides have been used) covering the nanotube with metal on top. The capacitance was measured between the nanotube and the top gate using a commercially available capacitance bridge. We also measure the transport through the tube and correlate the transport and capacitance measurements. For semiconducting tubes, we measure the difference in capacitance between the conducting state and the state where the charge carriers in the tube are depleted. The measured capacitance per unit length of the nanotube is in reasonable agreement with the geometric capacitance of a metal wire embedded in oxide near a conducting plane.

Donev, Luke A. K.; Ilani, Shahal; McEuen, Paul L.

2006-03-01

356

Thermal conductivity and thermal rectification in unzipped carbon nanotubes.  

PubMed

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

Ni, Xiaoxi; Zhang, Gang; Li, Baowen

2011-05-09

357

NonCarbon Nanotubes (Review). Part 3. Properties and Applications  

Microsoft Academic Search

The electronic, quantum, thermodynamic, mechanical, phonon, superconducting and other properties of non-carbon nanotubes and their promising applications are reviewed. A number of layered compounds is proposed as a basis for the synthesis of new non-carbon nanotubes.

Vladimir V. Pokropivnyi

2002-01-01

358

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

359

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

PubMed

We describe a novel tunable approach for the synthesis of carbon nanotube-silica nanobead composites. The control of nanotube morphology and bead size coupled with the versatility of silica chemistry makes these structures an excellent platform for the development of biosensors, or for optical, magnetic and catalytic applications. PMID:15685328

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

2004-12-15

360

Electrochemical storage of energy in carbon nanotubes and nanostructured carbons  

Microsoft Academic Search

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

Elzbieta Frackowiak; François Béguin

2002-01-01

361

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

PubMed

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

Daneshvar Tarigh, Ghazale; Shemirani, Farzaneh

2013-06-28

362

Carbon nanotube composite curing through absorption of microwave radiation  

Microsoft Academic Search

The microwave absorbing properties and subsequent heating of carbon nanotubes can be used to rapidly cure ceramic composites. With less than 1wt% carbon nanotube additives and 30–40W of directed microwave power (2.45GHz), bulk composite samples reach temperatures above 500°C within 1min. Multiwalled carbon nanotubes (MWNTs), functionalized MWNTs (f-MWNTs), raw single-walled carbon nanotubes (r-SWNTs) and purified SWNTs (p-SWNTs) were all used

Amanda L. Higginbotham; Padraig G. Moloney; Michael C. Waid; Juan G. Duque; Carter Kittrell; Howard K. Schmidt; Jason J. Stephenson; Sivaram Arepalli; Leonard L. Yowell; James M. Tour

2008-01-01

363

Raman spectroscopy of polystyrene nanofibers—Multiwalled carbon nanotubes composites  

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

364

Bio-functionalization of multi-walled carbon nanotubes.  

PubMed

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

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

2013-09-25

365

Carbon nanotube-based synthetic gecko tapes  

PubMed Central

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

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

2007-01-01

366

Gas Absorbtion and Interaction Inside Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Since the discovery of carbon nanotubes in 1991 by S. Iijima the field of Nanoscience has grown in leaps and bounds. Potential applications include nanowires for quantum computers, hydrogen storage devices in fuel cells, biosensors and bioreactors, and much more. The focus of this research has been to improve upon existing etching techniques to ``unzip'' the nanotubes allowing improved absorption of introduced gaseous species and, once introduced, to prompt chemical interaction between multiple gaseous species in the nanotubes using XPS. Implications of this research could extend to safe transportation of volatile gasses, increased efficiency filtration, and more. To date, a mixture of HNO3/H2O2 and H2SO4/H202 and an etching time of 1 week to a month has provided the best oxidation results while maintaining the structure of the carbon nanotubes. Initial spectra of trapped CO2 have been completed and further experiments including multiple species are planned.

Blackmore, William; Davis, Austin Buddy; Dillingham, T. Randall

2007-10-01

367

Agglomeration defects on irradiated carbon nanotubes  

SciTech Connect

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

Steini Moura, Cassio [Faculty of Physics, Pontificia Universidade Catolica do Rio Grande do Sul, 90619-900, Porto Alegre, RS (Brazil); Balzaretti, Naira Maria; Amaral, Livio [Institute of Physics, Universidade Federal do Rio Grande do Sul, C.P.: 15051, 91501-070, Porto Alegre, RS (Brazil); Gribel Lacerda, Rodrigo; Pimenta, Marcos A. [Universidade Federal de Minas Gerais, C.P.: 702, 31270-901, Belo Horizonte, MG (Brazil)

2012-03-15

368

Carbon nanotube polymer composites for photonic devices  

NASA Astrophysics Data System (ADS)

We report the fabrication of high optical quality single wall carbon nanotube polyvinyl alcohol composites and their application in nanotube based photonic devices. These show a broad absorption of semiconductor tubes centred at ˜1.55 ?m, the spectral range of interest for optical communications. The films are used as mode-lockers in an erbium doped fibre laser, achieving ˜700 fs mode-locked pulses. Raman spectroscopy shows no damage after a long time continuous laser operation.

Scardaci, V.; Rozhin, A. G.; Hennrich, F.; Milne, W. I.; Ferrari, A. C.

2007-03-01

369

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

370

How does water freeze inside carbon nanotubes?  

Microsoft Academic Search

Phase behavior of quasi-one-dimensional water confined inside a carbon nanotube is studied in the thermodynamic space of temperature, pressure, and diameter of the cylindrical container. Four kinds of solid-like ordered structures—ice nanotubes—form spontaneously from liquid-like disordered phases at low temperatures. In the model system that comprises of TIP4P water molecules interacting with each other via short-range Lennard–Jones and long-range Coulomb

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

2002-01-01

371

Phonons and Thermal Properties of Carbon Nanotubes  

Microsoft Academic Search

The thermal properties of carbon nanotubes display a wide range of behaviors which are related both to their graphitic nature\\u000a and their unique structure and size. The specific heat of individual nanotubes should be similar to that of two-dimensional\\u000a graphene at high temperatures, with the effects of phonon quantization becoming apparent at lower temperatures. Inter-tube\\u000a coupling in SWNT ropes, and

James Hone

2001-01-01

372

Electrical and thermal transport in carbon nanotubes  

Microsoft Academic Search

Owing to their atomic-level perfection, carbon nanotubes exhibit unusually high electrical and thermal conductivity. Our electrical transport calculations, performed using a scattering technique based on the Landauer-Büttiker formalism, suggest that the conductance of inhomogeneous multi-wall nanotubes may show an unusual fractional quantization behavior, in agreement with recent experimental data. Our calculations also indicate that due to the combination of a

David Tománek

2000-01-01

373

Electrical and thermal transport in carbon nanotubes  

Microsoft Academic Search

Owing to their atomic-level perfection, carbon nanotubes exhibit unusually high electrical and thermal conductivity. Our electrical transport calculations, performed using a scattering technique based on the Landauer-Bu¨ttiker formalism, suggest that the conductance of inhomogeneous multi-wall nanotubes may show an unusual fractional quantization behavior, in agreement with recent experimental data. Our calculations also indicate that due to the combination of a

David Toma´nek

2000-01-01

374

Half-metallic zigzag carbon nanotube dots  

Microsoft Academic Search

A comprehensive first-principles theoretical study of the electronic properties and half-metallic nature of finite zigzag carbon nanotubes is presented. Unlike previous reports, we find that all nanotubes studied present a spin-polarized ground state, where opposite spins are localized at the two zigzag edges in a long-range antifferomagnetic configuration. Relative stability analysis of the different spin states indicate that, for the

Oded Hod; Gustavo E. Scuseria

2008-01-01

375

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

376

Interactions Between Cultured Neurons and Carbon Nanotubes: A Nanoneuroscience Vignette  

PubMed Central

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

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

2009-01-01

377

Carbon Nanotubes Under High Pressure Probed by Resonance Raman Scattering  

NASA Astrophysics Data System (ADS)

The power of Raman spectroscopy for the study of the high-pressure evolution of carbon nanotubes is shown. After an introduction to carbon nanotubes and its resonance Raman scattering signal, we discuss the high-pressure Raman studies on single-wall carbon nanotubes with particular emphasis on the identification of pressure-induced structural and electronic transitions.

San-Miguel, Alfonso; Cailler, Christophe; Machon, Denis; Barros, Eduardo B.; Aguiar, Acrisio L.; Filho, Antonio G. Souza

378

Single Carbon Nanotube Based Ion Sensor for Gas Detection  

Microsoft Academic Search

This paper presents a new method for carbon nanotube based gas sensing. Instead of sensing the gas directly, the gas molecules are first ionized and then the ionized molecules are sensed by the single carbon nanotube based ion sensor. The adsorption of ionized gas molecule on the carbon nanotube surface introduces electrons into the material and consequently changes the current

Jiangbo Zhang; Ning Xi; Hoyin Chan; Guangyong Li

2006-01-01

379

Reactor scale modeling of multi-walled carbon nanotube growth  

Microsoft Academic Search

As the mechanisms of carbon nanotube (CNT) growth becomes known, it becomes important to understand how to implement this knowledge into reactor scale models to optimize CNT growth. In past work, we have reported fundamental mechanisms and competing deposition regimes that dictate single wall carbon nanotube growth. In this study, we will further explore the growth of carbon nanotubes with

Jeffrey J. Lombardo; Wilson K. S. Chiu

2011-01-01

380

Introduction to carbon nanotube and nanofiber smart materials  

Microsoft Academic Search

The potential use of carbon nanotubes and nanofibers as smart composite materials is discussed in this paper. An overview of the properties of carbon nanotube materials is presented, and then four applications under development are briefly discussed. The first application is electrochemical actuation in dry and aqueous environments. The second is a carbon nanotube polymer piezoresistive strain sensor developed for

Inpil Kang; Yun Yeo Heung; Jay H. Kim; Jong Won Lee; Ramanand Gollapudi; Srinivas Subramaniam; Suhasini Narasimhadevara; Douglas Hurd; Goutham R. Kirikera; Vesselin Shanov; Mark J. Schulz; Donglu Shi; Jim Boerio; Shankar Mall; Marina Ruggles-Wren

2006-01-01

381

Measurement of carbon nanotube-polymer interfacial strength  

Microsoft Academic Search

The force required to separate a carbon nanotube from a solid polymer matrix has been measured by performing reproducible nanopullout experiments using atomic force microscopy. The separation stress is found to be remarkably high, indicating that carbon nanotubes are effective at reinforcing a polymer. These results imply that the polymer matrix in close vicinity of the carbon nanotube is able

Asa H. Barber; Sidney R. Cohen; H. Daniel Wagnera

2003-01-01

382

Carbon nanotubes as nanomedicines: From toxicology to pharmacology  

Microsoft Academic Search

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

Lara Lacerda; Alberto Bianco; Maurizio Prato; Kostas Kostarelos

2006-01-01

383

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

384

Large spin-orbit coupling in carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

385

Synthesis of polycrystalline SnO 2 nanotubes on carbon nanotube template for anode material of lithium-ion battery  

Microsoft Academic Search

Polycrystalline tin oxide nanotubes have been prepared by a layer-by-layer technique on carbon nanotubes template. Firstly, the surface of carbon nanotubes was modified by polyelectrolyte. Then, a uniform layer of tin oxide nanoparticles was formed on the positive charged surface of carbon nanotubes via a redox process. At last, the polycrystalline tin oxide nanotubes were synthesized after calcination at 650°C

Ning Du; Hui Zhang; Bindi Chen; Xiangyang Ma; Xiaohua Huang; Jiangping Tu; Deren Yang

2009-01-01

386

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

387

Effect of nanotube waviness on the electrical conductivity of carbon nanotube-based composites  

Microsoft Academic Search

This paper reports the effect of nanotube waviness on the electrical conductivity of carbon nanotube-based composites using a percolation model. Wavy nanotubes are approximated by elongated polygons, and the current-carrying backbones of percolation clusters in the composite are identified by the direct electrifying algorithm. The tunneling resistance due to an insulating film of matrix material between crossing nanotubes is considered.

Chunyu Li; Erik T. Thostenson; Tsu-Wei Chou

2008-01-01

388

Multifunctional Carbon Nanotube Fiber Composites.  

National Technical Information Service (NTIS)

The project provides a spinning process that results in continuous nanotube composite fibers that are about an order of magnitude tougher than any fibers made by mankind or nature. We make two hundred-meter long reels of continuous nanotube-polymer compos...

R. H. Baughman S. Collins G. G. Wallace J. N. Barisci M. Kozlov

2004-01-01

389

Quantum oscillations and ferromagnetic hysteresis observed in iron filled multiwall carbon nanotubes.  

PubMed

We report on the electrical transport properties of single multiwall carbon nanotubes with and without an iron filling as a function of temperature and magnetic field. For the iron filled nanotubes the magnetoresistance shows a magnetic behavior induced by iron, which can be explained by taking into account a contribution of s-d hybridization. In particular, ferromagnetic-like hysteresis loops were observed up to 50 K for the iron filled multiwall carbon nanotubes. The magnetoresistance shows quantum interference phenomena such as universal conductance fluctuations and weak localization effects. PMID:22155967

Barzola-Quiquia, J; Klingner, N; Krüger, J; Molle, A; Esquinazi, P; Leonhardt, A; Martínez, M T

2011-12-08

390

Fabrication and magnetic characterization of ferromagnetic nanotubes  

NASA Astrophysics Data System (ADS)

During the last decade, interesting properties of magnetic nanowires have attracted much attention. Besides their interesting basic properties, there is evidence that these can be used in the fabrication of new nanodevices. Recently magnetic nanotubes have been successfully fabricated and have become a symbol of new and fast developing research area of nanotechnology because of their technological applications in patterned recording media,magentic sensors and magnetic biotechnology. Ferromagnetic nanotubes have been fabricated using templates (Alumite, PCTE) which can provide us a straight forward route to fabrication of the nanotubes.The anisotropy of the tubes is governed by shape anisotropy and the switching field of the tubes is consistent with that expected from curling mechanism in which the magnetization rotates within the plane of the tube wall.

Sharif, Rehana; Shahzadi, Shamaila; Yunan, Han; Ma, Ming; Xiu-Feng, Han

2008-03-01

391

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

2011-08-12

392

Selective microwave absorption of iron-rich carbon nanotube composites.  

PubMed

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

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

2010-03-01

393

Carbon nanotube films for ultrafast broadband technology.  

PubMed

Mode-locked sub-picosecond operation of Yb-, Er- and Tm:Hodoped fiber lasers operating at 1.05 microm, 1.56 microm and 1.99 microm, respectively, is demonstrated using the same sample carbon nanotube-based saturable absorber mirror. A mesh of single-walled carbon nanotubes was deposited on an Ag-mirror using a one-step dry-transfer contact press method to combine broadband saturable absorption and high reflectance properties. The novel fabrication method of the polymer-free absorber and device parameters determined using nonlinear reflectivity measurement are described in detail. To our knowledge the observed operation bandwidth of approximately 1 microm is the broadest reported to date for a single carbon nanotube-based saturable absorber. PMID:19219139

Kivistö, Samuli; Hakulinen, Tommi; Kaskela, Antti; Aitchison, Brad; Brown, David P; Nasibulin, Albert G; Kauppinen, Esko I; Härkönen, Antti; Okhotnikov, Oleg G

2009-02-16

394

Detection of gas atoms with carbon nanotubes  

PubMed Central

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

Arash, B.; Wang, Q.

2013-01-01

395

Analysis of thermal conductance of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) are being looked at as a promising material for the submicron or nanometre scale electronic and electro-mechanical devices. At this size, the thermal transport properties of the components become extremely important with regard to the proper functioning of the device. As it is difficult to accurately measure these properties in case of nano devices, predictions using modeling and simulation play an important role in the design of these devices. In this paper, we have estimated and analyzed the thermal conductance of one single-walled carbon nanotube (SWNT) depending upon its geometrical features. We have further extended the simulation to predict the thermal conductance of multi-walled carbon nanotubes (MWNTs). It was found that the SWNT depicts high thermal conductance which depends largely on its geometry and chirality and an MWNT shows very high conductance varying with tube diameter, length and number of shells.

Jain, Neeraj; Harsh

2010-07-01

396

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.

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

2012-01-01

397

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

398

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

399

DC Anhydrous Electrodeposition of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Electrodeposition is a versatile technique to fabricate carbon nanotube films on conducting substrates. Due to different responses of metallic and semiconducting nanotubes against electric field in solution, it can be used to discriminate nanotubes based on these types. Depending on whether the applied field is ac or dc, nanotubes are moved across electrodes by either dielectrophoresis or electrophoresis. In ordinary dc electrodeposition, water has been used as a solvent. We have found that, using organic solvents from which water is carefully removed, low dc fields electrodeposit nanotubes quite efficiently [1]. A millimeter thick film can be obtained within a minute with 15V/cm. Furthermore, the process is highly selective; the films are adhered so strongly that it requires scratching the substrate to remove, all nanotubes form thin straight bundles that lie parallel to the substrate, the films show no metallic Raman peaks and have 4 order of magnitude higher resistivity than the original sample [2]. A recent study shows that the electric field is not responsible for adhesion. Other than the first layer that is directly on the substrate surface, the van der Waals force dominates adhesion of nanotubes. [1] Y. Abe, R. Tomuro, M. Sano, Adv. Mater. 17, 2192 (2005). [2] R. Tomuro, T. Matsumoto, M. Sano, Jpn. J. Appl. Phys. 45, L578 (2006).

Sano, Masahito; Matsumoto, Takanori

2008-03-01

400

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

401

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

402

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

PubMed

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

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

2013-09-06

403

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

PubMed

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

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

2011-09-26

404

A tunable carbon nanotube electromechanical oscillator  

NASA Astrophysics Data System (ADS)

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

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

2004-09-01

405

Decoration of carbon nanotubes with iron oxide  

SciTech Connect

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

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

2006-04-15

406

Decoration of carbon nanotubes with iron oxide  

NASA Astrophysics Data System (ADS)

A magnetic composite of multiwalls carbon nanotubes (MWNTs) decorated with iron oxide nanoparticles was synthesized successfully by a simple and effective chemistry precipitation method. The composite was characterized by X-ray diffraction analysis (XRD), Mössbauer spectrum (MS), transmission electron microscopy (TEM), and Fourier transform spectroscopy (FTIR) techniques. The patterns of XRD and MS indicated that MWNTs, ?-Fe2O3, and Fe3O4 coexisted in the composite. The TEM observation indicated that the nanoparticles of iron oxide were attached on the surface of the MWNTs, and the sizes of the particles ranged from 25 to 80 nm. FTIR spectra showed that SO4- functional groups existed on the surface of MWNTs after modification by sodium dodecylbenzene sulfonic acid (SDBS), which could immobilize Fe3+ ions onto the MWNTs. The hysteresis loops of the MWNTs and decorated MWNTs were measured by vibrating sample magnetometer (VSM), and the results showed that the composite was ferromagnetism with the saturated magnetization of 20.07 emu/g, and the coercive of 163.44 Oe.

Huiqun, Cao; Meifang, Zhu; Yaogang, Li

2006-04-01

407

Crosstalk analysis of carbon nanotube bundle interconnects  

NASA Astrophysics Data System (ADS)

Carbon nanotube (CNT) has been considered as an ideal interconnect material for replacing copper for future nanoscale IC technology due to its outstanding current carrying capability, thermal conductivity, and mechanical robustness. In this paper, crosstalk problems for single-walled carbon nanotube (SWCNT) bundle interconnects are investigated; the interconnect parameters for SWCNT bundle are calculated first, and then the equivalent circuit has been developed to perform the crosstalk analysis. Based on the simulation results using SPICE simulator, the voltage of the crosstalk-induced glitch can be reduced by decreasing the line length, increasing the spacing between adjacent lines, or increasing the diameter of SWCNT.

Zhang, Kailiang; Tian, Bo; Zhu, Xiaosong; Wang, Fang; Wei, Jun

2012-02-01

408

Carbon nanotubes as nanopipette: modelling and simulations  

NASA Astrophysics Data System (ADS)

This paper shows that carbon nanotubes can be applied to a nanopipette. Nanospace in atomic force microscope multi-wall carbon nanotube tips is filled with molecules and atoms with charges and then, the tips can be applied to nanopipette when the encapsulated media flow off under applying electrostatic forces. Since the nanospace inside the tips can be refilled, the tips can be permanently used in ideal conditions of no chemical reaction and no mechanical deformation. Molecular dynamics simulations for nanopipette applications showed the possibility of nanolithography or single-metallofullerene-transistor array fabrication.

Hwang, Ho Jung; Byun, Ki Ryang; Kang, Jeong Won

2004-06-01

409

Carbon nanotube fibers as torsion sensors  

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

410

Carbon nanotube based transparent conductive thin films.  

PubMed

Carbon nanotube (CNT) based optically transparent and electrically conductive thin films are fabricated on plastic substrates in this study. Single-walled carbon nanotubes (SWNTs) are chemically treated with a mixture of concentrated sulfuric acid and nitric acid before being dispersed in aqueous surfactant-contained solutions. SWNT thin films are prepared from the stable SWNT solutions using wet coating techniques. The 100 nm thick SWNT thin film exhibits a surface resistivity of 6 kohms/square nanometer with an average transmittance of 88% on the visible light range, which is three times better than the films prepared from the high purity as-received SWNTs. PMID:17025106

Yu, X; Rajamani, R; Stelson, K A; Cui, T

2006-07-01

411

Fluctuation broadening in carbon nanotube resonators  

PubMed Central

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

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

2012-01-01

412

Modified Kirkendall effect for fabrication of magnetic nanotubes.  

PubMed

In this paper, we successfully synthesize Fe(OH)(3) nanotubes involving the Kirkendall effect. Depending on the calcination conditions, both haematite and magnetite nanotubes are produced. This approach also provides a new synthetic alternative to nanotubes of nonlamellar-structured materials. The as-synthesized magnetite nanotubes have an application as a magnetic resonance imaging contrast agent. PMID:20198246

Wang, Qian; Geng, Baoyou; Wang, Shaozhen; Ye, Yixing; Tao, Bo

2010-01-13

413

Carbon Nanotube Based Deuterium Ion Source for Improved Neutron Generators  

SciTech Connect

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

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

2009-03-10

414

Carbon Nanotube Production in CO Laser Pumped Carbon Monoxide Plasmas  

NASA Astrophysics Data System (ADS)

A novel method for the synthesis of carbon nanotubes will be presented. Carbon monoxide in a CO-Ar gas mixture is optically pumped using a continuous wave CO laser. The CO molecules absorb the laser radiation on the lowest 10 vibrational transitions and transfer energy to high vibrational states by vibration-vibration energy exchange collisions. This leads to a highly nonequilibrium energy distribution in the CO which provides enough energy for the CO disproportionation reaction to occur: CO + CO arrow C + CO_2. This experimental technique consequently produces the free carbon necessary for the growth of carbon nanotubes and other carbon clusters while maintaining near room temperature in the plasma. Our technique can produce substantial quantities of nanotubes at low pressure (50 Torr) due to the efficient carbon production and is scalable to higher pressures and therefore, to larger production quantities. We will present the effect of metal catalysts on production rates and nanotube quality for our experimental technique as well as effects of plasma temperature and gas pressures. Single- and multi-walled carbon nanotubes have been observed in the deposited material with concentrations of better than 50 %. The plasma conditions are monitored using emission spectroscopy.

Ploenjes, Elke; Palm, Peter; Subramaniam, Vish; Adamovich, Igor; Rich, William; Viswanathan, Babu; Fraser, Hamish

2000-10-01

415

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

416

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Structural feature and electronic property of an (8, 0) carbon-silicon carbide nanotube heterojunction  

NASA Astrophysics Data System (ADS)

A supercell of a nanotube heterojunction formed by an (8, 0) carbon nanotube (CNT) and an (8, 0) silicon carbide nanotube (SiCNT) is established, in which 96 C atoms and 32 Si atoms are included. The geometry optimization and the electronic property of the heterojunction are implemented through the first-principles calculation based on the density functional theory (DFT). The results indicate that the structural rearrangement takes place mainly on the interface and the energy gap of the heterojunction is 0.31 eV, which is narrower than those of the isolated CNT and the isolated SiCNT. By using the average bond energy method, the valence band offset and the conduction band offset are obtained as 0.71 and -0.03 eV, respectively.

Liu, Hong-Xia; Zhang, He-Ming; Hu, Hui-Yong; Song, Jiu-Xu

2009-02-01

417

Molecular Beam Epitaxy Synthesis of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes have been synthesized using molecular beam epitaxy techniques. 3D Mo (111) islands grown expitaxially on sapphire substrate were used as the catalytic template. Carbon flux was produced using an e-beam hearth with a pure graphite target, and it contained molecular carbon species from C2 to C6 with a maximum concentration of C3. Nucleation and initial growth of carbon were investigated using in-situ real-time RHEED and in-situ SPM. Initial deposition of Carbon leads to the formation of Mo carbide nanocrystals, which forms a periodic superstructure with an in-plane spacing of about 16 Åinside the Mo crystal. As carbon deposition continues, the carbide superstructure undergoes a kinetic coarsenning process, where the in-plane spacing increases. The carbide superstructure and the associated kinetic processes are found to be critical for the formation of carbon nanotubes. Particularly, the spacing of the carbide appears to control the size of nanotubes. Effects of other catalytic templates, particularly those that form alloys with carbon, have been studied also.

Tsui, Frank

2000-03-01

418

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

Microsoft Academic Search

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

M. M. Shokrieh; R. Rafiee

2010-01-01

419

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

SciTech Connect

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

None

2010-03-01

420

Purification Procedures for Single-Wall Carbon Nanotubes.  

National Technical Information Service (NTIS)

This report summarizes the comparison of a variety of procedures used to purify carbon nanotubes. Carbon nanotube material is produced by the arc process and laser oven process. Most of the procedures are tested using laser-grown, single-wall nanotube (SW...

O. P. Gorelik P. Nikolaev S. Arepalli

2001-01-01

421

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...

422

Site-selective radiation damage of collapsed carbon nanotubes  

SciTech Connect

Carbon nanotubes can flatten into collapsed tubes with bulbs along either edge. The strong anisotropy in the graphitic radiation damage threshold both explains the rapid destruction of face-on flattened nanotubes and can be exploited to selectively modify the structure of edge-on flattened nanotubes, thereby creating one-dimensional sp2 carbon with noncontinuous transverse boundary conditions.

Crespi, Vincent H.; Chopra, Nasreen G.; Cohen, Marvin L.; Zettl, A.; Radmilovic, Velimir

1998-05-15

423

Adsorption of polymer coated magnetite composite particles onto carbon nanotubes and their magnetorheology  

Microsoft Academic Search

Polymer coated nano-sized magnetite (Fe3O4) particles with multiwalled carbon nanotube (MWNT) nanohybrid were prepared by four step procedures in this study. Initially, magnetic particles were synthesized by a co-precipitation method with ammonium hydroxide and oleic acid, and then the produced particles were coated with polyacrylamide (PAAm). Finally PAAm coated magnetite particles (Mag-PAAm) were physically adsorbed onto multiwalled carbon nanotubes (MWNT)

S. W. Ko; M. S. Yang; H. J. Choi

2009-01-01

424

Preparation of molecularly imprinted polymers on the surface of magnetic carbon nanotubes with a pseudo template for rapid simultaneous extraction of four fluoroquinolones in egg samples.  

PubMed

Fluoroquinolones (FQs) have emerged as one of the most important class of antibiotics. Due to their low concentration in bio-matrix samples which contain a lot of interfering substances, the efficient solid phase extraction and accurate determination of FQs remain a challenge. In this paper, a new strategy for the isolation and enrichment of FQs from egg samples was obtained by molecularly imprinted polymers on the surface of magnetic carbon nanotubes (MCNTs@MIP), which not only can be collected and separated rapidly by an external magnetic field, but also have a high specific surface area, outstanding mechanical properties and specific recognition for FQs. MCNTs@MIP were prepared using ofloxacin as a pseudo template, methacrylic acid as a functional monomer, and ethylene glycol dimethacrylate as a cross-linker. The characteristics of the MCNTs@MIP were assessed by transmission electron microscopy (TEM), multipoint Brunauer-Emmett-Teller (BET) analysis, vibrating sample magnetometry (VSM), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The results of the adsorption experiments not only demonstrated rapid dynamic adsorption but also showed a high selectivity toward FQs. An extraction method using MCNTs@MIP coupled with high performance liquid chromatography (HPLC) was developed for the determination of four FQs in egg samples. The recovery of four FQs ranged from 95.2% ± 3.2% to 100.7% ± 3.1% and the detection limits ranged from 0.25-0.40 ng g(-1). The results demonstrate that the proposed method based on pseudo template MCNTs@MIP is a promising approach for the preconcentration, purification, and simultaneous analysis of four FQs in bio-matrix samples. PMID:23620872

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

2013-06-01

425

Electrical properties of long suspended single-wall carbon nanotubes  

Microsoft Academic Search

Suspended single-wall carbon nanotubes are grown on top of pre-deposited metal electrodes. This configuration allows investigation of the electrical properties of suspended nanotubes up to 10 microns long. Previous experiments have been limited to nanotubes less than 1 micron. Semi-conducting and metallic nanotubes are investigated at low temperatures and with a back gate. Because of their suspended nature these nanotubes

Nathan Franklin; Tom Tombler; Hongjie Dai

2002-01-01

426

FABRICATION AND FIELD EMISSION PROPERTIES OF CARBON NANOTUBE CATHODES  

Microsoft Academic Search

A variety of carbon nanotube films have been fabricated and tested as cold cathodes. A spray deposition technique was developed for processing as-grown bulk nanotubes, both single-walled and multi-walled, into films of randomly oriented nanotubes. Films of randomly oriented multi-walled nanotubes were grown using thermal chemical vapor deposition, and arrays of well -aligned multi-walled nanotubes have been fabricated using a

C. BOWER; O. ZHOU; W. ZHU; A. G. RAMIREZ; G. P. KOCHANSKI

2000-01-01

427

Resonant magneto-conductance of a suspended carbon nanotube quantum dot  

Microsoft Academic Search

We address the electronic resonant transport in the presence of a transverse magnetic field through the single level of a suspended carbon nanotube acting as a quantum oscillator. We predict a negative magneto-conductance with a magnetic-field-induced narrowing of the resonance line and a reduction of the conductance peak when the nanotube is asymmetrically contacted to the leads. At finite bias

G. Rastelli; M. Houzet; F. Pistolesi

2010-01-01

428

The conversion of polyaniline nanotubes to nitrogen-containing carbon nanotubes and their comparison with multi-walled carbon nanotubes  

Microsoft Academic Search

Polyaniline (PANI) nanotubes were prepared by the oxidation of aniline in solutions of acetic or succinic acid, and subsequently carbonized in a nitrogen atmosphere during thermogravimetric analysis running up to 830°C. The nanotubular morphology of PANI was preserved after carbonization. The molecular structure of the original PANI and of the carbonized products has been analyzed by FTIR and Raman spectroscopies.

Miroslava Trchová; Elena N. Konyushenko; Jaroslav Stejskal; Jana Ková?ová; Gordana ?iri?-Marjanovi?

2009-01-01

429

Conductivity enhancement of carbon nanotube composites by electrolyte addition  

NASA Astrophysics Data System (ADS)

The conductivity of carbon nanotubes and polyvinyl alcohol composites is significantly improved by addition of Fe2(SO4)3. The coordinated cations between nanotubes play a crucial role in lowering intertube hopping magnitude.

Li, Hui-Ching; Lu, Sheng-Yi; Syue, Sen-Hong; Hsu, Wen-Kuang; Chang, Shih-Chin

2008-07-01

430

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

National Technical Information Service (NTIS)

The mechanics and chemistry of carbon nanotubes have relevance for their numerous electronic applications. Mechanical deformations such as bending and twisting affect the nanotube's conductive properties, and at the same time they possess high strength an...

D. Srivastava

2000-01-01

431

High-density selective placement methods for carbon nanotubes  

Microsoft Academic Search

Selective placement can be achieved with carbon nanotubes dispersed in N-methyl pyrrolidone (NMP) on aminopropyltriethoxysilane patterns. Investigations by AFM show a high deposition density of the nanotubes compared to water–surfactant solutions.

Emmanuel Valentin; Stephane Auvray; Julie Goethals; Justin Lewenstein; Laurence Capes; Arianna Filoramo; Aline Ribayrol; Ray Tsui; Jean-Philippe Bourgoin; Jean-Noel Patillon

2002-01-01

432

Surface plasmon observed for carbon nanotubes.  

National Technical Information Service (NTIS)

This paper presents parallel electron energy loss spectra (PEELS) results, obtained for individual carbon nanotubes, using nanoprobe techniques (1-2 nm diameter electron beam), energy resolution 0.5 eV and collection times of 4-25 sec. The aim was to use ...

L. A. Bursill P. A. Stadelmann J. L. Peng S. Prawer

1993-01-01

433

CARBON NANOTUBE MATERIALS FOR HYDROGEN STORAGE  

Microsoft Academic Search

Carbon single-wall nanotubes (SWNTs) are essentially elongated pores of molecular dimensions and are capable of adsorbing hydrogen at relatively high temperatures and low pressures. This behavior is unique to these materials and indicates that SWNTs are the ideal building block for constructing safe, efficient, and high energy density adsorbents for hydrogen storage applications. In past work we developed methods for

A. C. Dillon; T. Gennett; J. L. Alleman; K. M. Jones; P. A. Parilla

434

Functionalized Carbon Nanotubes for Mixed Matrix Membrane  

Microsoft Academic Search

Carbon nanotubes (CNTs) have generated great interest within the many areas of nanotechnology due to their superior and outstanding physical properties. However effective dispersion in many solvents has imposed limitations upon the use of CNTs in a number of novel applications. Functionalization presents a solution for CNTs to be more soluble which make them integrate well into any organic, inorganic

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

2009-01-01

435

Nanoscale Application for Carbon Nanotube Arrays.  

National Technical Information Service (NTIS)

The original goals for the research program were to: 1) fabricate an interconnected array of single wall carbon nanotubes (SWNT) and 2) use the device to investigate cellular signaling in live cells. The most challenging part of this research (as anticipa...

R. C. Farrow

2007-01-01

436

Chemistry of Carbon Nanotubes for Everyone  

ERIC Educational Resources Information Center

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

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

2012-01-01

437

Thermal transport properties of carbon nanotube  

Microsoft Academic Search

Because of their unique structure, novel properties and potential applications, carbon nanotubes (CNTs) have attracted significant attention since their discovery. The thermal properties of CNTs are of interest for basic science as well as for technological applications. In the present paper, our experimental studies of the thermal transport properties of CNTs in recent years were introduced. The measurement techniques and

Huaqing Xie; Yang Li

2009-01-01

438

Photothermal effects of immunologically modified carbon nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes have a great potential in the biomedical applications. To use carbon nanotubes in the treatment of cancer, we synthesized an immunologically modified single-walled carbon nanotube (SWNT) using a novel immunomodifier, glycated chitosan (GC), as an effective surfactant for SWNT. This new composition SWNT-GC was stable due to the strong non-covalent binding between SWNT and GC. The structure of SWNT-GC is presented in this report. The photothermal effect of SWNT-GC was investigated under irradiation of a near-infrared laser. SWNT-GC retained the optical properties of SWNT and the immunological properties of GC. Specifically, the SWNT-GC could selectively absorb a 980-nm light and induce desirable thermal effects in tissue culture and in animals. It could also induce tumor cell destruction, controlled by the laser settings and the doses of SWNT and GC. Laser+SWNT-GC treatment could also induce strong expression of heat shock proteins on the surface of tumor cells. This immunologically modified carbon nanotube could be used for selective photothermal interactions in noninvasive tumor treatment.

Griswold, Ryan T.; Henderson, Brock; Goddard, Jessica; Tan, Yongqiang; Hode, Tomas; Liu, Hong; Nordquist, Robert E.; Chen, Wei R.

2013-02-01

439

Formation of thick dielectrophoretic carbon nanotube fibers  

Microsoft Academic Search

The aim of this work was to study the formation process of dielectrophoretic (DEP) carbon nanotube fibers (CNT-fibers) and characterize the fiber properties relevant to their technological applications. The fiber diameter was shown to increase when applied voltage was increased (up to 350 Vpp) and when retraction speed was decreased (down from 400 µm s ? 1) in accordance with

Margo Plaado; Robert Matias Mononen; Rünno Lõhmus; Ilmar Kink; Kristjan Saal

2011-01-01

440

DNA and carbon nanotubes as medicine  

Microsoft Academic Search

The identification of disease-related genes and their complete nucleotide sequence through the human genome project provides us with a remarkable opportunity to combat a large number of diseases with designed genes as medicine. However, gene therapy relies on the efficient and nontoxic transport of therapeutic genetic medicine through the cell membranes, and this process is very inefficient. Carbon nanotubes, due

William Cheung; Francesco Pontoriero; Oleh Taratula; Alex M. Chen; Huixin He

2010-01-01

441

High Performance Electrolyte Gated Carbon Nanotube Transistors  

Microsoft Academic Search

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

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

2002-01-01

442

Charge pumping in carbon nanotube quantum dots  

Microsoft Academic Search

We investigate charge pumping in carbon nanotube quantum dots driven by the electric field of a surface acoustic wave. We find that at small driving amplitudes, the pumped current reverses polarity as the conductance is tuned through a Coulomb blockade peak using a gate electrode. We study the behavior as a function of wave amplitude, frequency and direction and develop

M. R. Buitelaar; V. Kashcheyevs; P. J. Leek; V. I. Talyanskii; C. G. Smith; D. Anderson; G. A. C. Jones; J. Wei; D. H. Cobden

443

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

444

Carbon nanotubes and nanofibers in catalysis  

Microsoft Academic Search

This review analyses the literature from the early 1990s until the beginning of 2003 and covers the use of carbon nanotubes (CNT) and nanofibers as catalysts and catalysts supports. The article is composed of three sections, the first one explains why these materials can be suitable for these applications, the second describes the different preparation methods for supporting metallic catalysts

Philippe Serp; Massimiliano Corrias; Philippe Kalck

2003-01-01

445

Effective torsional properties of carbon nanotubes  

Microsoft Academic Search

In this paper, a dynamic continuum modeling method is proposed to evaluate effective torsional structural properties of single-walled carbon nanotubes without any need to assume their fictitious wall thickness. The dynamic continuum modeling method has been developed based on the energy equivalence principle as well as on the molecular mechanics. The proposed dynamic continuum modeling method is applied to armchair

Usik Lee; Changho Lee; Jaesang Lee

2007-01-01

446

Molecularly imprinted polymers immobilized on carbon nanotube  

Microsoft Academic Search

Molecularly imprinted polymers (MIPs) are artificial materials containing recognition sites with high affinity and selectivity. This study aims to immobilize MIPs on the surface of carbon nanotube (CNT) in an effort to develop biosensor system based on CNT transistor using MIPs as a probe material. As a linking molecule of MIPs to CNT, acrylated Tween 20 was synthesized by reacting

Eunhye Lee; Dong-Won Park; Jeong-O Lee; Dae Su Kim; Bong Hee Lee; Beom Soo Kim

2008-01-01

447

Electromigration Forces on Ions in Carbon Nanotubes  

Microsoft Academic Search

We calculate the electromigration forces on ions such as adsorbed alkali metal atoms in a carbon nanotube transistor. The forces are especially large in the turn-on regime of the transistor and much smaller in the off and on states. Electromigration in the channel is driven almost exclusively by the wind force. The sign of the ``effective valence'' Z* is independent

S. Heinze; Neng-Ping Wang; J. Tersoff

2005-01-01

448

Carbon nanotube-reinforced aluminium strips  

Microsoft Academic Search

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

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

2008-01-01

449

Growth of decorated carbon nano-tubes  

Microsoft Academic Search

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

Ralph Kurt; Ayatollah Karimi; Volker Hoffmann

2001-01-01

450

Tuning Carbon Nanotube Band Gaps with Strain  

Microsoft Academic Search

We show that the band structure of a carbon nanotube (NT) can be dramatically altered by mechanical strain. We employ an atomic force microscope tip to simultaneously vary the NT strain and to electrostatically gate the tube. We show that strain can open a band gap in a metallic NT and modify the band gap in a semiconducting NT. Theoretical

E. D. Minot; Yuval Yaish; Vera Sazonova; Ji-Yong Park; Markus Brink; Paul L. McEuen

2003-01-01

451

Carbon nanotubes: A bright future for defects  

NASA Astrophysics Data System (ADS)

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

Wang, Qing Hua; Strano, Michael S.

2013-10-01

452

Double Quantum Dots in Carbon Nanotubes.  

National Technical Information Service (NTIS)

We study the few-electron eigenspectrum of a carbon-nanotube double quantum dot with spin-orbit coupling. Exact calculation are combined with a simple model to provide an intuitive and accurate description of single- particle and interaction effects. For ...

A. M. Rey B. Wunsch E. Demler J. Von Stecher M. Lukin

2010-01-01

453

Trigonal Anisotropy in Graphite and Carbon Nanotubes  

Microsoft Academic Search

We discuss here how the trigonal warping effect of the electronic structure is relevant to optical processes in graphite and carbon nanotubes. The electron-photon, electron-phonon, and elastic scattering matrix elements have a common factor of the coefficients of Bloch wave funtions of the A and B atoms in the graphite unit cell. Because of the three fold symmetry around the

R. Saito; J. Jiang; A. Gruneis; K. Sato; Y. Oyama; Ge. G. Samsonidze; S. G. Chou; G. Dresselhaus; M. S. Dresselhaus; L. G. Cancado; C. Fantini; A. Jorio; M. A. Pimenta

2006-01-01

454

Original magnetic alignment of a nematic phase containing single-walled nanotubes.  

PubMed

Dispersions of single-walled carbon nanotubes in a 4-pentyl-4'-cyano-biphenyl nematic liquid crystal matrix are studied by X-ray scattering. For some mixtures, the addition of nanotubes strongly modifies the properties of the matrix: under a magnetic field, the nematic director is aligned perpendicular to the field, whereas it is parallel to it for pure 4-pentyl-4'-cyano-biphenyl. This original modification of liquid crystal alignment by the addition of nanotubes raises new questions about nanotubes and liquid crystal interactions. PMID:15112547

Da Cruz, C; Launois, P; Veber, M

455

Synthesis, characterisation and applications of coiled carbon nanotubes.  

PubMed

Coiled carbon nanotubes are helical carbon structures formed when heptagonal and pentagonal rings are inserted into the hexagonal backbone of a 'straight' nanotube. Coiled carbon nanotubes have been reported with both regular and irregular helical structures. In this work the structure, growth mechanism(s), synthesis, properties and potential applications of coiled carbon nanotubes are reviewed. Published data suggests that coiled carbon nanotube synthesis occurs due to nonuniform extrusion of carbon from a catalyst surface. To date, coiled carbon nanotubes have been synthesised using catalyst modification techniques including: (i) the addition of S or P containing compounds during synthesis; (ii) the use of binary or ternary metal catalysts; (iii) the use of microwaves to create a local temperature gradient around individual catalyst particles and; (iv) the use of pH control during catalyst preparation. In most instances coiled carbon nanotubes are produced as a by-product; high yield and/or large-scale synthesis of coiled carbon nanotubes remains problematic. The qualitative analysis of coiled carbon nanotubes is currently hindered by the absence of specific characterisation data in the literature, e.g., oxidation profiles measured by thermogravimetric analysis and Raman spectra of pure coiled carbon nanotube samples. PMID:20355423

Hanus, Monica J; Harris, Andrew T

2010-04-01

456

Carbon Nanotubes: From Symmetry to Applications  

NASA Astrophysics Data System (ADS)

In this chapter, we show how the concept of symmetry gives theoretical explanation of the properties, which made carbon nanotubes (NTs) one of the most interesting materials of nanotechnology. First, in Sect. 3.1, we consider basic facts on single-wall carbon nanotubes (SWCNTs), including their configuration and symmetry. Then, we discuss double-wall nanotubes.Next, Sect. 3.2 is devoted to elementary symmetry-based physical properties. More precisely, we explain the energy spectrum of electrons and phonons, showing that as the consequence of the symmetry, energies must be arranged in the so-called bands. Elementary properties of these band structures may be a priory discussed, yielding easily famous conducting law, showing strong dependence of conductivity on the type of nanotube. Conserved quantum numbers enable us to extract selection rules for various physical processes. This way, radial breathing mode appears to be very important for the characterization of the samples by Raman spectroscopy. Also, optical properties are derived.Finally, in Sect. 3.3, mutual interaction between the walls of double-wall nanotubes is discussed. It is explained why this interaction is very weak, which is used to propose nanomachines with almost superslippery parts.

Damnjanovi?, M.

457

SU(4) Kondo effect in carbon nanotube quantum dots  

NASA Astrophysics Data System (ADS)

We investigate theoretically the non-equilibrium transport properties of carbon nanotube quantum dots. Owing to the two-dimensional band structure of graphene, a double orbital degeneracy plays the role of a pseudo-spin, which is entangled with the spin. Quantum fluctuations between these four degrees of freedom result in an SU(4) Kondo effect at low temperatures. This exotic Kondo effect manifests as a four-peak splitting in the non-linear conductance when an axial magnetic field is applied [1]. Recent transport experiments in carbon nanotube quantum dots [2] clearly support our theoretical findings. [1] M. S. Choi, R. Lopez and R. Aguado, cond-mat/0411665 (2004). [2] P. Jarillo-Herrero, J. Kong, H. S. J. van der Zant, C. Dekker, L. P. Kouwenhoven and S. De Franceschi, to be published (2004).

Aguado, Ramon; Choi, Mahn-Soo; Lopez, Rosa

2005-03-01

458

Chemical vapor deposition of pyrolytic carbon on carbon nanotubes  

Microsoft Academic Search

The chemical vapor deposition of the pyrocarbon from a CH4+H2 mixture is investigated using nanofilamentous substrates. The process consists of growing carbon nanotubes via a catalytic process, which then are thickened by pyrolytic carbon deposition to reach diameters in the nanometer to micrometer range. A key characteristic of the experimental reactor used was the long length of its isothermal zone,

Hatem Allouche; Marc Monthioux; Ronald L Jacobsen

2003-01-01

459

Atomic nanotube welders: boron interstitials triggering connections in double-walled carbon nanotubes.  

PubMed

Here we demonstrate that the incorporation of boron (B) atoms between double-walled carbon nanotubes (DWNTs) during thermal annealing (1400-1600 degrees C) results in covalent nanotube "Y" junctions, DWNT coalescence, and the formation of flattened multiwalled carbon nanotubes (MWNTs). These processes occur via the merging of adjacent tubes, which is triggered by B interstitial atoms. We observe that B atom interstitials between DWNTs are responsible for the rapid establishment of covalent connections between neighboring tubes (polymerization), thereby resulting in the fast annealing of the carbon cylinders with B atoms embedded in the newly created carbon nanotube network. Once B is in the lattice, tube faceting (polygonization) starts to occur, and the electronic properties are expected to change dramatically. Therefore, B atoms indeed act as atomic nanotube fusers (or welders), and this process could now be used in assembling novel electronic nanotube devices, nanotube networks, carbon</