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1

Magnetic Carbon Nanotubes Tethered with Maghemite Nanoparticles  

NASA Astrophysics Data System (ADS)

We describe a novel, facile method for the synthesis of magnetic carbon nanotubes (m-CNTs) decorated with monodisperse ?-Fe2O3 magnetic (maghemite) nanoparticles and their aligned feature in a magnetic field. The tethering of the nanoparticles was achieved by the initial activation of the surface of the CNTs with carboxylic acid groups, followed by the attachment of the ?-Fe2O3 nanoparticles via a modified sol-gel process. Sodium dodecylbenzene sulfonate (NaDDBS) was introduced into the suspension to prevent the formation of an iron oxide 3D network. Various characterization methods were used to confirm the formation of well-defined maghemite nanoparticles. The tethered nanoparticles imparted magnetic characteristics to the CNTs, which became superparamagnetic. The m-CNTs were oriented parallel to the direction of a magnetic field. This has the potential of enhancing various properties, e.g. mechanical and electrical properties, in composite materials.

Kim, Il Tae; Nunnery, Grady; Jacob, Karl; Schwartz, Justin; Liu, Xiaotao; Tannenbaum, Rina

2011-03-01

2

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

3

Preparation and characterization of biocompatible magnetic carbon nanotubes  

NASA Astrophysics Data System (ADS)

Magnetic carbon nanotubes consisting of multi-wall carbon nanotubes (MWNTs) core and Fe3O4 shell were successfully prepared by in situ thermal decomposition of Fe(acac)3 or FeCl3 or Fe(CO)5 in 2-pyrrolidone containing acid treated MWNTs at 240 °C with the protection of nitrogen gas. The samples were characterized by TEM, XRD, SEAD, XPS and superconducting quantum interference device. Also, their biocompatibility was compared with naked carbon nanotubes. The results showed that after coated with Fe3O4 nanoparticles, the obtained magnetic carbon nanotubes show superparamagnetic characteristic at room temperature, and their blocking temperature is about 80 K. The magnetic properties of the nanotubes are relevant to the content of magnetic particles, increasing content of magnetic nanoparticles leads to higher blocking temperature and saturation magnetization. The results of antimicrobial activities to bacterial cells (Escherichia coli) showed that the MWNTs have antimicrobial activity, while the magnetic nanotubes are biocompatible even with a higher concentration than that of MWNTs.

Shan, Yan; Chen, Kezheng; Yu, Xuegang; Gao, Lian

2010-11-01

4

Nonequilibrium giant loop currents and orbital magnetism in carbon nanotubes  

NASA Astrophysics Data System (ADS)

Recent experiments have shown that carbon nanotubes can have large orbital magnetic moments (˜10?B). Although isolated carbon nanotubes in equilibrium in external magnetic fields have been theoretically studied, nonequilibrium transport of nanotubes attached to electrodes has yet to be established. Based on Keldysh formalism, we analyze currents flowing in carbon nanotubes attached to electrodes with finite bias voltages. We show that large magnetic moments are generated from giant loop currents circulating around the tube, which makes carbon nanotubes ``molecular solenoids''. While this is an example of the quantum loop current when incident electrons are resonant to degenerate levels of molecules as proposed by Nakanishi and Tsukada [Surf. Sci. 438, 305 (1999)], a speciality of the nanotubes is that they have inherent doubly-degenerate states (propagating clockwise and anticlockwise around the tube). We have further identified the full conditions for large loop currents that include the position of the electrodes and the chirality of the tube. The current-voltage characteristic and effects of external magnetic fields are also discussed.

Tsuji, Naoto; Takajo, Shigehiro; Aoki, Hideo

2007-03-01

5

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

6

Magnetic Nanoparticles Decorated Multiwalled Carbon Nanotubes Dispersed Nanofluids  

NASA Astrophysics Data System (ADS)

In the proposed work iron oxide coated multiwalled carbon nanotubes (Fe2O3/MWNT) was synthesized and made magnetic nanofluid by dispersing it in water. The thermal conductivity of Fe2O3/MWNT nanofluid was investigated with magnetic field and without magnetic field for different volume fractions. The results show that high thermal conductivity Fe2O3/MWNT nanofluids with low volume fractions can be synthesized using the current method. The sample was characterized with different experimental techniques.

Baby, Tessy Theres; Ramaprabhu, Sundara

2011-07-01

7

Efficient synthesis of tailored magnetic carbon nanotubes via a noncovalent chemical route.  

PubMed

We report here an efficient noncovalent chemical route to dense and uniform assembly of magnetic nanoparticles onto multi-walled carbon nanotubes within a single-layer configuration. While preserving the electrical conduction behavior of the nanotube network itself, the resulting carbon nanotube derivatives exhibit a distinct superparamagnetism, and can be magnetically manipulated via a quick and reversible mode. PMID:21116557

Li, Xianglong; Thompson, Joe D; Zhang, Yingying; Brady, Christina I; Zou, Guifu; Mack, Nathan H; Williams, Darrick; Duque, Juan G; Jia, Quanxi; Doorn, Stephen K

2011-02-01

8

Cell Creeping and Controlled Migration by Magnetic Carbon Nanotubes  

PubMed Central

Carbon nanotubes (CNTs) are tubular nanostructures that exhibit magnetic properties due to the metal catalyst impurities entrapped at their extremities during fabrication. When mammalian cells are cultured in a CNT-containing medium, the nanotubes interact with the cells, as a result of which, on exposure to a magnetic field, they are able to move cells towards the magnetic source. In the present paper, we report on a model that describes the dynamics of this mammalian cell movement in a magnetic field consequent on CNT attachment. The model is based on Bell’s theory of unbinding dynamics of receptor-ligand bonds modified and validated by experimental data of the movement dynamics of mammalian cells cultured with nanotubes and exposed to a magnetic field, generated by a permanent magnet, in the vicinity of the cell culture wells. We demonstrate that when the applied magnetic force is below a critical value (about Fc ? 10?11 N), the cell ‘creeps’ very slowly on the culture dish at a very low velocity (10–20 nm/s) but becomes detached from the substrate when this critical magnetic force is exceeded and then move towards the magnetic source.

2010-01-01

9

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

10

Magnetorheological properties of a magnetic nanofluid with dispersed carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

Felicia, Leona J.; Philip, John

2014-02-01

11

Magnetic nanotubes  

DOEpatents

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

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

2010-11-16

12

Sensitive magnetic force detection with a carbon nanotube resonator  

NASA Astrophysics Data System (ADS)

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

Willick, Kyle; Haapamaki, Chris; Baugh, Jonathan

2014-03-01

13

Post-synthesis alignment of chemically modified carbon nanotubes in magnetic fields.  

PubMed

In this paper we present an improved procedure to prepare carbon nanotubes bundles functionalized with magnetite nanoparticles. Carbon nanotubes (CNTs) have been modified by hydrophobic adsorption of a carboxylic acid derivative and the previously synthesized magnetite nanoparticles have been attached to the acid groups. Electron microscopy studies show a high density of magnetite nanoparticles on the surface of CNTs. These modified carbon nanotubes become magnetic and can be appropriately oriented by using external magnetic fields. PMID:19908504

Marquez, F; Morant, C; Sanz, J M; Elizalde, E

2009-10-01

14

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

15

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

16

Dynamic interaction between localized magnetic moments in carbon nanotubes  

NASA Astrophysics Data System (ADS)

Magnetic moments dilutely dispersed in a metallic host tend to be coupled through the conduction electrons of the metal. This indirect exchange coupling (IEC), known to occur for a variety of magnetic materials embedded in several different metallic structures, is of rather long range, especially for low-dimensional structures like carbon nanotubes. Motivated by recent claims that the indirect coupling between magnetic moments in precessional motion has a much longer range than its static counterpart, we consider here how magnetic atoms adsorbed to the walls of a metallic nanotube respond to a time-dependent perturbation that induces their magnetic moments to precess. By calculating the frequency-dependent spin susceptibility, we are able to identify resonant peaks whose respective widths provide information about the dynamic aspect of the IEC. We show that by departing from a purely static representation to another in which the moments are allowed to precess, we change from what is already considered a long-range interaction to another whose range is far superior. In other words, localized magnetic moments embedded in a metallic structure can feel each other's presence more easily when they are set in precessional motion. We argue that such an effect can have useful applications leading to large-scale spintronics devices.

Costa, A. T.; Muniz, R. B.; Ferreira, M. S.

2008-06-01

17

Synthesis of magnetic carbon nanotube and photocatalytic dye degradation ability.  

PubMed

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

Mahmoodi, Niyaz Mohammad

2014-09-01

18

Ordered arrays of magnetic metal nanotubes and nanowires encapsulated with carbon tubes.  

PubMed

The ordered arrays of magnetic metal (including Fe, Co and Ni) nanotubes and nanowires encapsulated with carbon tubes are controllably synthesized by employing the array of C tubes as second-order template and combining with electrodeposition technique. The wall thickness and diameter of carbon nanotubes are uniform along the whole tubes; also the wall thickness of inner metal nanotubes is adjustable from 25 nm to solid nanowires. These composite structures are characterized by X-ray diffractometer (XRD), energy-dispersive spectrometry (EDS), Raman scattering spectrum, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The magnetic properties show that coaxial nanotubes and nanocables composite arrays all exhibit magnetic anisotropy with the easy direction perpendicular to axis of the metal nanotubes or nanowires except the Ni at C coaxial nanotubes array that has no preferable magnetization axis. PMID:19049046

Gao, Culling; Tao, Feifei; Lin, Weiwei; Xu, Zheng; Xue, Ziling

2008-09-01

19

Electrostatic waves in carbon nanotubes with an axial magnetic field  

NASA Astrophysics Data System (ADS)

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

Abdikian, Alireza; Bagheri, Mehran

2013-10-01

20

Magnetic Property Measurements on Single Wall Carbon Nanotube-Polyimide Composites  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

21

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

22

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

PubMed

Due to outstanding mechanical and electronic properties, carbon nanotube nanoelectromechanical systems (NEMS) were recently proposed as ultrasensitive magnetometers for single-molecule magnets (SMM). In this article, we describe a noninvasive grafting of a SMM on a carbon nanotube NEMS, which conserves both the mechanical properties of the carbon nanotube NEMS and the magnetic properties of the SMM. We will demonstrate that the nonlinearity of a carbon nanotube's mechanical motion can be used to probe the reversal of a molecular spin, associated with a bis(phthalocyaninato)terbium(III) single-molecule magnet, providing an experimental evidence for the detection of a single spin by a mechanical degree of freedom on a molecular level. PMID:23802618

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

2013-07-23

23

Selective actuation of arrays of carbon nanotubes using magnetic resonance.  

PubMed

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

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

2013-07-23

24

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

25

Magnetic properties of Fe-5d (Os, Ir, and Pt) nanowires encapsulated in carbon nanotubes  

NASA Astrophysics Data System (ADS)

Using the first-principles density functional calculations, we explored the magnetic properties of Fe-X (X=Os, Ir, and Pt) nanowires encapsulated in a (4,4) carbon nanotubes. It is found that these wires possess giant magnetic anisotropy energies due to sizable spin-orbit coupling along with induced magnetization of 5d metals.

Wang, Junhua; Jo, Chulsu; Wu, Ruqian

2008-01-01

26

Studies of Magnetization Reversal and Switching Characteristics of Individual Iron Filled Carbon Nanotubes using Cantilever Magnetometry  

Microsoft Academic Search

Iron-filled carbon nanotubes (FeCNTs) form a class of novel materials in which a single-crystal iron nanowire is encapsulated within a carbon nanotube. The iron filled core can be grown to significant lengths (10--15 mum). Their narrow diameters (15--25 nm) and high crystalline quality make them promising candidates for studying magnetism in thin nanowires. We present a detailed characterization of the

Palash Banerjee; M. R. Herman; D. V. Pelekhov; Yu. Obukhov; P. Chris Hammel; F. Wolny; S. Philippi; T. Mühl; A. Leonhardt; B. Büchner

2010-01-01

27

Filling of Carbon Nanotubes: Containers for Magnetic Probes and Drug Delivery  

Microsoft Academic Search

\\u000a Nanotechnology is a broad scientific field but one of the most explored materials in nanotechnology is carbon nanotube (CNT).\\u000a A large proportion of research on CNTs is focused on their huge potential for biomedical applications. Within this context,\\u000a the synthesis of carbon nanotubes filled with magnetic materials has been widely investigated, especially with iron due to\\u000a its excellent ferromagnetic characteristics.

E. Borowiak-Palen; C. Tripisciano; M. Rümmeli; S. Costa; X. Chen; R. J. Kalenczuk

28

The electronic and magnetic properties of carbon nanotubes interacting with iron atoms  

NASA Astrophysics Data System (ADS)

We investigate electronic and magnetic properties of carbon nanotubes interacting with Fe atoms through first-principles theoretical calculations. For a single Fe atom on the tube surface, due to the curvature effect, there exists a difference in effective coordination number between inside and outside of the nanotube, and a complete promotion of 4s electrons into 3d orbitals occurs inside the nanotube. When Fe atoms are encapsulated in the form of nanowires inside the nanotube, their magnetic properties strongly depend on wire thickness. For thin nanowires with very weak interactions between Fe and C atoms, magnetic moments are similar to those for their free-standing nanowires, and electron conduction mostly occurs through the wires well protected from oxidation. On the other hand, the magnetic moments of thicker nanowires are greatly reduced.

Kang, Yong-Ju; Chang, K. J.

2006-04-01

29

Magnetic dipolar interaction in NiFe nanodot arrays formed on vertical carbon nanotubes  

Microsoft Academic Search

A new and simple method for the fabrication of densely packed magnetic nanodot arrays was developed using conventional sputtering deposition at room temperature. An anodized alumina template was employed for the formation of nanodot assemblies, consisting of carbon nanotubes (CNTs) and magnetic nanodot arrays. Each nanodot was formed exactly on top of a CNT and was arranged with a well-ordered

Chunghee Nam; Youn-Su Kim; W. B. Kim; B. K. Cho

2008-01-01

30

Electronic and magnetic properties of single-wall carbon nanotubes filled with iron atoms  

NASA Astrophysics Data System (ADS)

We study the electronic and magnetic properties of single-wall carbon nanotubes filled with Fe nanowires through local-spin-density-functional calculations. We find that the magnetic moments of Fe-filled carbon nanotubes for the ferromagnetic state are greatly enhanced due to the reduced coordination number of the Fe atoms on the nanowire surface, compared with bulk Fe. The increase of magnetic moments is more effective for thin nanowires, where the Fe atoms interact very weakly with the nanotube and thus their magnetic properties inside the tube are similar to those for the free-standing nanowires. For thick Fe nanowires, undercoordinated Fe atoms interact more strongly with the carbon nanotube, and thereby the magnetic moments are reduced. The analysis of the densities of states near the Fermi level shows that electron conduction mostly occurs along the Fe wires protected from oxidation by carbon coating. Our calculations suggest that for applications to spin transport devices, it is desirable to form thin Fe wires inside single-wall nanotubes with large diameters.

Kang, Yong-Ju; Choi, Jin; Moon, Chang-Youn; Chang, K. J.

2005-03-01

31

On converse magnetoelectric effect in a twisted carbon nanotube under the influence of applied magnetic field  

NASA Astrophysics Data System (ADS)

We present theoretical results concerning some unusual properties of linear converse magnetoelectric effect (MEE) in a twisted carbon nanotube under the influence of applied magnetic field Bz. In addition to twist angle ? dependence of the zero-field paramagnetic MEE coefficient ?, we found that for magnetic fields Bz exceeding deformation induced intrinsic pseudomagnetic field Bzd??? (generated by the constant twist), ? changes its sign and becomes diamagnetic. The estimates of the model parameters suggest quite an optimistic possibility to experimentally realize the discussed phenomena in twisted carbon nanotubes and graphene nanoribbons.

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

2013-12-01

32

Perpendicular magnetization of long iron carbide nanowires inside carbon nanotubes due to magnetocrystalline anisotropy  

NASA Astrophysics Data System (ADS)

Single crystal iron carbide nanowires contained in multiwalled carbon nanotubes have been prepared by aerosol-based thermal chemical vapor deposition. Investigations by transmission electron microscopy reveal the crystallographic [010] axis of the orthorhombic Fe3C nanowires to be predominantly aligned along the nanotube axis. Despite the high aspect ratio of the Fe3C nanowires, magnetic force microscopy measurements imply single domain behavior with the easy magnetic axis of the nanowires perpendicular to the wire axis. In agreement with the structural results, these findings show that the magnetic behavior is dominated by the magnetocrystalline anisotropy contribution, causing the easy axis to be along the [001] direction.

Weissker, Uhland; Löffler, Markus; Wolny, Franziska; Lutz, Matthias Uljas; Scheerbaum, Nils; Klingeler, Rüdiger; Gemming, Thomas; Mühl, Thomas; Leonhardt, Albrecht; Büchner, Bernd

2009-09-01

33

Dual modality photothermal OCT and magnetic resonance imaging with carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

34

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

35

High Yield Magnetic Nanoparticles Filled Multiwalled Carbon Nanotubes Using Pulsed Laser Deposition  

Microsoft Academic Search

We present a high yield filling technique of multiwalled carbon nanotubes (MWNTs), grown vertically on a SiO2 substrate, with magnetic nanoparticles using pulsed laser deposition (PLD). Magnetization measurements in-plane and out- of-plane with respect to the sample surface indicate reasonable coercivity estimated at 0.4 T. The magnetic anisotropy is however found to be randomly oriented, indicating a polycrystalline structure. The

Dereje Seifu; Shashi P. Karna

2008-01-01

36

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

37

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

Microsoft Academic Search

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

Ferenc Simon; Rudolf Pfeiffer; Hans Kuzmany

2007-01-01

38

Electronic and magnetic properties of Fe clusters inside finite zigzag single-wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

Density functional calculations of the electronic structure of the Fe12 cluster encapsulated inside finite single-wall zigzag carbon nanotubes of indices (11,0) and (10,0) have been performed. Several Fe12 isomers have been considered, including elongated shape isomers aimed to fit well inside the nanotubes, and the icosahedral minimum energy structure. We analyze the structural and magnetic properties of the combined systems, and how those properties change compared to the isolated systems. A strong ferromagnetic coupling between the Fe atoms occurs both for the free and the encapsulated Fe12 clusters, but there is a small reduction (3-7.4?B) of the spin magnetic moment of the encapsulated clusters with respect to that of the free ones (?=38?B). The reduction of the magnetic moment is mostly due to the internal redistribution of the spin charges in the iron cluster. In contrast, the spin magnetic moment of the carbon nanotubes, which is zero for the empty tubes, becomes nonzero (1-3?B) because of the interaction with the encapsulated cluster. We have also studied the encapsulation of atomic Fe and the growth of small Fen clusters (n=2, 4, 8) encapsulated in a short (10,0) tube. The results suggest that the growth of nanowires formed by distorted tetrahedral Fe4 units will be favorable in (10,0) nanotubes and nanotubes of similar diameter.

Horga, F. I.; Mañanes, A.; López, M. J.; Alonso, J. A.

2013-02-01

39

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

40

Magnetic catalyst residues and their influence on the field electron emission characteristics of low temperature grown carbon nanotubes  

Microsoft Academic Search

We report the electron paramagnetic resonance characteristics of catalytic residues for in situ grown carbon nanotube field electron emitter and present direct evidence that field electron emission in carbon nanotube sheets grown on various catalytic nanodots\\/SiO2-coated Si substrate with low-pressure chemical vapor deposition is influenced by the magnetism of catalytic metals and thus the electrical properties of the nanotubes. The

Yun-Hi Lee; D. H. Kim; Byeong-Kwon Ju

2006-01-01

41

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

PubMed

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

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

2014-01-21

42

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

43

Alignment of carbon nanotubes comprising magnetically sensitive metal oxides in heat transfer nanofluids  

Microsoft Academic Search

High speed microscopy was utilized to allow real time visualization of the movement of single walled carbon nanotubes (SWNT) with magnetically sensitive nanoparticles (Fe2O3) and a chemical surfactant (NaDSSB) in water. Initially, entangled SWNT, Fe2O3 and NaDSSB mixtures were randomly dispersed in the fluid. Upon extended exposure to the magnetic field, the mixture slowly vibrated, the nanoparticles straightened and aligned

Haiping Hong; Xinning Luan; Mark Horton; Chen Li; G. P. Peterson

2011-01-01

44

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

PubMed

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

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

2011-07-01

45

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

46

Control of growth orientation for carbon nanotubes  

NASA Astrophysics Data System (ADS)

Laterally aligned carbon nanotubes were synthesized on substrates over iron nanoparticles using chemical vapor deposition. In addition, aligned carbon nanotubes grown vertically and with tilt angle to the substrates were produced, which means that it is possible to grow aligned carbon nanotubes at any angle relative to the substrate. The growth direction of the carbon nanotubes was controlled by a magnetic field that is applied in the process of adhering catalyst particles on silicon oxide substrates from dispersion. The ferromagnetic property of the iron nanoparticles fixes them in a defined orientation under magnetic field, which results in aligned growth of the carbon nanotubes. These results indicate that carbon nanotubes preferentially grow from certain facets of the catalyst particles, suggesting a crucial clue in investigating the growth mechanism of carbon nanotubes. The laterally aligned carbon nanotubes could make it possible to integrate them in nanoelectronic devices, such as a channel for field-effect transistors.

Lee, Ki-Hong; Cho, Jeong-Min; Sigmund, Wolfgang

2003-01-01

47

Microwave response of magnetized hydrogen plasma in carbon nanotubes: multiple reflection effects  

SciTech Connect

We derived simple sets of equations to describe the microwave response of the magnetized hydrogen plasma slab embedded inside carbon nanotubes, which were grown by iron-catalyzed high-pressure disproportionation. These equations, which are useful when interference effects due to multiple reflections between plasma film interfaces are small, were used to analyze the reflection, absorption, and transmission coefficients of the magnetized hydrogen plasma slab. A discussion on the effects of the continuously changing external magnetic field and hydrogen plasma parameters on the reflected power, absorbed power, and transmitted power in the system is presented.

Moradi, Afshin

2010-04-01

48

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

NASA Astrophysics Data System (ADS)

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

Bagheri, Mehran; Abdikian, Alireza

2014-04-01

49

Carbon nanotube nanoelectrode arrays  

DOEpatents

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

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

2008-11-18

50

Material dependence of magnetic force microscopy performance using carbon nanotube probes: Experiments and simulation  

NASA Astrophysics Data System (ADS)

We investigated the dependence of the performance of magnetic force microscopy (MFM) on magnetic coating materials by using carbon nanotube (CNT) probes. The magnetic structures of CNT-MFM probes with CoFe(80:20), CoFe(30:70), and CoCr(80:20) coatings were essentially the same in the simulations, but their magnetic properties, such as stability after magnetic reversal, varied slightly in the experiments. It was found that a larger saturation magnetic moment (Ms) is of advantage for attaining high spatial resolution. Although the distinction was hard to see in the MFM images, the experiments and simulations showed that CNT probes coated with high Ms materials gave stronger perturbations to soft magnetic materials than probes coated with low Ms materials.

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

2014-03-01

51

Carbon nanotube clusters as universal bacterial adsorbents and magnetic separation agents.  

PubMed

The magnetic susceptibility and high bacterial affinity of carbon nanotube (CNT) clusters highlight their great potential as a magnetic bio-separation agent. This article reports the CNT clusters' capability as "universal" bacterial adsorbents and magnetic separation agents by designing and testing a multiwalled carbon nanotube (MWNT) cluster-based process for bacterial capturing and separation. The reaction system consisted of large clusters of MWNTs for bacterial capture and an external magnet for bio-separation. The designed system was tested and optimized using Escherichia coli as a model bacterium, and further generalized by testing the process with other representative strains of both gram-positive and gram-negative bacteria. For all strains tested, bacterial adsorption to MWNT clusters occurred spontaneously, and the estimated MWNT clusters' adsorption capacities were nearly the same regardless of the types of strains. The bacteria-bound MWNT clusters also responded almost instantaneously to the magnetic field by a rare-earth magnet (0.68 Tesla), and completely separated from the bulk aqueous phase and retained in the system. The results clearly demonstrate their excellent potential as highly effective "universal" bacterial adsorbents for the spontaneous adsorption of any types of bacteria to the clusters and as paramagnetic complexes for the rapid and highly effective magnetic separations. PMID:19856390

Moon, Hyung-Mo; Kim, Jin-Woo

2010-01-01

52

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

PubMed Central

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

2011-01-01

53

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

54

Plumbing carbon nanotubes.  

PubMed

Since their discovery, the possibility of connecting carbon nanotubes together like water pipes has been an intriguing prospect for these hollow nanostructures. The serial joining of carbon nanotubes in a controlled manner offers a promising approach for the bottom-up engineering of nanotube structures--from simply increasing their aspect ratio to making integrated carbon nanotube devices. To date, however, there have been few reports of the joining of two different carbon nanotubes. Here we demonstrate that a Joule heating process, and associated electro-migration effects, can be used to connect two carbon nanotubes that have the same (or similar) diameters. More generally, with the assistance of a tungsten metal particle, this technique can be used to seamlessly join any two carbon nanotubes--regardless of their diameters--to form new nanotube structures. PMID:18654444

Jin, Chuanhong; Suenaga, Kazu; Iijima, Sumio

2008-01-01

55

Magnetic dipolar interaction in NiFe nanodot arrays formed on vertical carbon nanotubes.  

PubMed

A new and simple method for the fabrication of densely packed magnetic nanodot arrays was developed using conventional sputtering deposition at room temperature. An anodized alumina template was employed for the formation of nanodot assemblies, consisting of carbon nanotubes (CNTs) and magnetic nanodot arrays. Each nanodot was formed exactly on top of a CNT and was arranged with a well-ordered structure in a wide range of area. It was also found that the size of dots and the distance between dots can be tailored by changing the length of CNTs, inducing a change of strength of dipolar interaction between nanodots. PMID:21836284

Nam, Chunghee; Kim, Youn-Su; Kim, W B; Cho, B K

2008-11-26

56

Magnetic dipolar interaction in NiFe nanodot arrays formed on vertical carbon nanotubes  

NASA Astrophysics Data System (ADS)

A new and simple method for the fabrication of densely packed magnetic nanodot arrays was developed using conventional sputtering deposition at room temperature. An anodized alumina template was employed for the formation of nanodot assemblies, consisting of carbon nanotubes (CNTs) and magnetic nanodot arrays. Each nanodot was formed exactly on top of a CNT and was arranged with a well-ordered structure in a wide range of area. It was also found that the size of dots and the distance between dots can be tailored by changing the length of CNTs, inducing a change of strength of dipolar interaction between nanodots.

Nam, Chunghee; Kim, Youn-Su; Kim, W. B.; Cho, B. K.

2008-11-01

57

Topological Origin of Edge States and Boundary Magnetic Moments in Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Nanostructures like carbon nanotubes have potential to exhibit many different shapes of boundaries. When a carbon nanotube is truncated with a certain type of edges, boundary states localized near the edges appear at the Fermi level. It is a reflection of special topological character of the 2 dimensional carbon sheet which is similar to the topological origin of edges states in the Quantum Hall effects ( S. Ryu and Y. Hatsugai, Phys. Rev. Lett. 89, 077002 (2002)). Starting from lattice models, low energy effective theories are constructed which describe electron correlation effects on the boundary states. By the renormalization group analyses together with the open boundary bosonization, we show that the repulsive bulk interactions suppress the charge fluctuations at boundaries, and assist the spin polarization ( S. Ryu and Y. Hatsugai, cond-mat/0211008). We also discuss effects of Coulomb interaction and edge magnetic structures of the carbon nanotubes focusing on the boundary physics by the approximation free quantum Monte Carlo technique ( Y.Otsuka, S. Ryu and Y. Hatsugai, unpublished).

Hatsugai, Yasuhiro; Ryu, Shinsei; Otsuka, Yuichi

2003-03-01

58

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

59

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

60

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

NASA Astrophysics Data System (ADS)

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

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

2009-07-01

61

Joining carbon nanotubes.  

PubMed

To fully exploit the exceptional electronic and mechanical properties of carbon nanotubes in real-world applications, it is desirable to create carbon nanotube networks in which separate, multiple nanotubes are joined so that as many as possible of the properties of single nanotubes are conserved. In this review we summarize the progress made towards this goal, covering techniques including electron and ion beam irradiation, Joule heating and spark plasma sintering. PMID:21952820

Roberts, G Seth; Singjai, Pisith

2011-11-01

62

Studies of Magnetization Reversal and Switching Characteristics of Individual Iron Filled Carbon Nanotubes using Cantilever Magnetometry  

NASA Astrophysics Data System (ADS)

Iron-filled carbon nanotubes (FeCNTs) form a class of novel materials in which a single-crystal iron nanowire is encapsulated within a carbon nanotube. The iron filled core can be grown to significant lengths (10--15 ?m). Their narrow diameters (15--25 nm) and high crystalline quality make them promising candidates for studying magnetism in thin nanowires. We present a detailed characterization of the magnetic properties of a single FeCNT. These were measured by attaching individual FeCNTs to silicon cantilevers and performing ultrasensitive cantilever magnetometry. We find that the magnetization reversal in the FeCNT occurs at an exceptionally well defined and reproducible switching field and in a single step. These switching fields are characterized by a narrow distribution (˜1 Gauss) and their measured temperature dependence reveals that their magnetization reversal is thermally activated. We also compare and contrast these results with the low temperature switching behavior of high anisotropy individual micron sized SmCo particles and FePt nanoparticles.

Banerjee, Palash; Herman, M. R.; Pelekhov, D. V.; Obukhov, Yu.; Hammel, P. Chris; Wolny, F.; Philippi, S.; Mühl, T.; Leonhardt, A.; Büchner, B.

2010-03-01

63

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

64

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

PubMed

We report the magnetic behavior, relaxometry, phantom magnetic resonance imaging (MRI), and near-infrared (NIR) photoluminescence spectroscopy of gadolinium (Gd) catalyzed single-walled carbon nanotubes (Gd-SWCNTs). Gd-SWCNTs are paramagnetic with an effective magnetic moment of 7.29??B . Gd-SWCNT solutions show high r 1 and r 2 relaxivities at very low (0.01?MHz) to clinically relevant (61?MHz) magnetic fields (r 1???130?mM(-1)?s(-1), r 2???160?mM(-1)?s(-1)). Analysis of nuclear magnetic resonance dispersion profiles using Solomon, Bloembergen, and Morgan equations suggests that multiple structural and dynamic parameters such as rotational correlation time [Formula: see text], rate of water exchange [Formula: see text], and the number of fast-exchanging water molecules within the inner sphere q may be responsible for the increase in r 1 and r 2 relaxivity. The T 1 weighted MRI signal intensity (gradient echo sequence; repetition time (TR)?=?66?ms, echo time (TE)?=?3?ms, flop angle?=?108°) of Gd-SWCNT phantom solution is 14 times greater than the Gd-based clinical MRI contrast agent Magnevist. Additionally, these nanotubes exhibit near infrared fluorescence with distinct E11 transitions of several semiconducting SWCNTs. Taken together, these results demonstrate that Gd-SWCNTs have potential as a novel, highly efficacious, multimodal MRI-NIR optical imaging contrast agent. PMID:23653487

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

2013-04-01

65

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

PubMed Central

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

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

2013-01-01

66

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

67

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

68

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

NASA Astrophysics Data System (ADS)

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

Ghasemi, Ali

2013-03-01

69

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

70

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

SciTech Connect

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

Huang, P; Schwegler, E; Galli, G

2008-11-14

71

Quantitative detection of single walled carbon nanotube in water using DNA and magnetic fluorescent spheres.  

PubMed

Carbon nanotubes (CNTs) possess unique properties that have led to an increase in their research and usage for a wide variety of fields. This growing demand of CNTs poses a major public health risk given its unregulated release into the environment. Unfortunately there is a significant information gap on the actual quantity of CNTs in the environment due to limitation of existing detection methods. This is mainly owing to the ubiquitous carbon chemistry of CNT. In response we developed a method (CNT-capture method) that is able to structurally differentiate CNT from other interference carbon materials in an aqueous medium. The affinity between single walled nanotubes (SWNTs) and specific single stranded DNA (ssDNA) was employed to capture SWNTs in water. SWNT-specific separation was obtained via magnetic separation. Dual fluorescent labels attached to sandwich ssDNA probes were used for quantification. The specific affinity between DNA and SWNTs was verified and no significant side-interactions were observed. With optimized incubation duration (30 min) and buffer composition (10(-7) % sodium dodecyl sulfate and pH 7.9), a calibration curve of quantification (R(2) = 0.90) was obtained with a range of SWNT concentration (0.05-10 ?g/mL) against graphene as a planar analog. Comparison to other spectroscopy based methods was carried out to highlight the specificity and sensitivity of the presented method for CNT detection in aquatic sample. PMID:23214724

Mota, Linda C; Ureña-Benavides, Esteban E; Yoon, Yeomin; Son, Ahjeong

2013-01-01

72

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

73

Squeezing carbon nanotubes  

NASA Astrophysics Data System (ADS)

In this paper we briefly review the high pressure Raman studies on single and double walled carbon nanotubes focussing on the perssure dependence of the low frequency radial breathing vibrational modes. Previous work on single walled carbon nanotube bundles have shown that the normalized pressure-induced frequency shift, = (1/R) (dR/dP) D2, where R is the radial mode frequency and D is the nanotube diameter. We show here that the R-modes due to the inner tubes in double walled carbon nanotubes, have a very small, diameter independent value for , as predicted for the case of isolated tubes.

Venkateswaran, Uma D.

2004-11-01

74

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

75

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

76

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

PubMed

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

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

2014-05-15

77

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

PubMed

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

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

2012-01-01

78

Nanocomposites of vertically aligned single-walled carbon nanotubes by magnetic alignment and polymerization of a lyotropic precursor.  

PubMed

We demonstrate a novel path for the fabrication of thin-film polymer nanocomposites containing vertically aligned single-walled carbon nanotubes (SWNTs). Liquid crystal mesophases of hexagonally packed cylindrical micelles orient with their long axes parallel to an applied magnetic field and template the alignment of SWNTs sequestered in the micellar cores. The mesophase is a stable single-phase material containing monomers that can be polymerized after nanotube alignment to form the nanocomposite polymer. The space-pervasive nature of magnetic fields and the tunable physicochemical properties of multicomponent mesophases make this an attractive approach that can be leveraged for application in diverse nanocomposite systems. PMID:20954699

Mauter, Meagan S; Elimelech, Menachem; Osuji, Chinedum O

2010-11-23

79

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

80

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

PubMed

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

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

2012-12-11

81

Carbon nanotube intramolecular junctions  

Microsoft Academic Search

The ultimate device miniaturization would be to use individual molecules as functional devices. Single-wall carbon nanotubes (SWNTs) are promising candidates for achieving this: depending on their diameter and chirality, they are either one-dimensional metals or semiconductors. Single-electron transistors employing metallic nanotubes and field-effect transistors employing semiconducting nanotubes have been demonstrated. Intramolecular devices have also been proposed which should display a

Zhen Yao; Henk W. Ch. Postma; Leon Balents; Cees Dekker

1999-01-01

82

Carbon Nanotubes in Neuroscience  

PubMed Central

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

Malarkey, Erik B.

2010-01-01

83

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

PubMed

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

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

2013-08-01

84

Covalent enzyme immobilization onto carbon nanotubes using a membrane reactor  

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

85

Electronic properties of Cs-intercalated single-walled carbon nanotubes derived from nuclear magnetic resonance  

NASA Astrophysics Data System (ADS)

We report on the electronic properties of Cs-intercalated single-walled carbon nanotubes (SWNTs). A detailed analysis of the 13C and 133Cs nuclear magnetic resonance (NMR) spectra reveals an increased metallization of the pristine SWNTs under Cs intercalation. The 'metallization' of CsxC materials where x=0-0.144 is evidenced from the increased local electronic density of states (DOS) n(EF) at the Fermi level of the SWNTs as determined from spin-lattice relaxation measurements. In particular, there are two distinct electronic phases called ? and ? and the transition between these occurs around x=0.05. The electronic DOS at the Fermi level increases monotonically at low intercalation levels x<0.05 (?-phase), whereas it reaches a plateau in the range 0.05<=x<=0.143 at high intercalation levels (?-phase). The new ?-phase is accompanied by a hybridization of Cs(6s) orbitals with C(sp2) orbitals of the SWNTs. In both phases, two types of metallic nanotubes are found with a low and a high local n(EF), corresponding to different local electronic band structures of the SWNTs.

Abou-Hamad, E.; Goze-Bac, C.; Nitze, F.; Schmid, M.; Aznar, R.; Mehring, M.; Wågberg, T.

2011-05-01

86

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

2014-01-01

87

D0 magnetism in Ca doped narrow carbon nanotubes: First principle chirality effect study  

NASA Astrophysics Data System (ADS)

Curvature has always had crucial effects on the physical properties of narrow carbon nanotubes (CNTs) and here spin-polarized density functional calculations were employed to study electronic and magnetic properties of calcium-decorated narrow (5,5) and (9,0)CNTs with close diameters (˜7 Å) and different chiralities. Our results showed that chirality had great impact on the electronic structure and magnetization of the doped CNTs. In addition, internally or externally doping of the calcium atoms was studied comparatively and although for the (9,0)CNT the internal doping was the most stable configuration, which involves a novel kind of spin-polarization originated from Ca-4s electrons, but for the (5,5)tube the external doping was the most stable one without any spin-polarization. On the other hand, calcium doping in the center of the (5,5)CNT was an endothermic process and led to the spin-polarization of unoccupied Ca-3d orbitals via direct exchange interaction between adjacent Ca atoms. In the considered systems, the existence of magnetization in the absence of any transition-metal elements was an example of valuable d0 magnetism title.

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

2014-06-01

88

Carbon nanotube macroelectronics  

NASA Astrophysics Data System (ADS)

In this dissertation, I discuss the application of carbon nanotubes in macroelectronis. Due to the extraordinary electrical properties such as high intrinsic carrier mobility and current-carrying capacity, single wall carbon nanotubes are very desirable for thin-film transistor (TFT) applications such as flat panel display, transparent electronics, as well as flexible and stretchable electronics. Compared with other popular channel material for TFTs, namely amorphous silicon, polycrystalline silicon and organic materials, nanotube thin-films have the advantages of low-temperature processing compatibility, transparency, and flexibility, as well as high device performance. In order to demonstrate scalable, practical carbon nanotube macroelectroncis, I have developed a platform to fabricate high-density, uniform separated nanotube based thin-film transistors. In addition, many other essential analysis as well as technology components, such as nanotube film density control, purity and diameter dependent semiconducting nanotube electrical performance study, air-stable n-type transistor fabrication, and CMOS integration platform have also been demonstrated. On the basis of the above achievement, I have further demonstrated various kinds of applications including AMOLED display electronics, PMOS and CMOS logic circuits, flexible and transparent electronics. The dissertation is structured as follows. First, chapter 1 gives a brief introduction to the electronic properties of carbon nanotubes, which serves as the background knowledge for the following chapters. In chapter 2, I will present our approach of fabricating wafer-scale uniform semiconducting carbon nanotube thin-film transistors and demonstrate their application in display electronics and logic circuits. Following that, more detailed information about carbon nanotube thin-film transistor based active matrix organic light-emitting diode (AMOLED) displays is discussed in chapter 3. And in chapter 4, a technology to fabricate air-stable n-type semiconducting nanotube thin-film transistor is developed and complementary metal--oxide--semiconductor (CMOS) logic circuits are demonstrated. Chapter 5 discusses the application of carbon nanotubes in transparent and flexible electronics. After that, in chapter 6, a simple and low cost nanotube separation method is introduced and the electrical performance of separated nanotubes with different diameter is studied. Finally, in chapter 7 a brief summary is drawn and some future research directions are proposed with preliminary results.

Zhang, Jialu

89

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

90

Functionalization of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

Webber, Stephen E.

2003-01-01

91

Carbon nanotubes paste electrode  

Microsoft Academic Search

The performance of carbon nanotubes paste electrodes (CNTPE) prepared by dispersion of multi-wall carbon nanotubes (MWNT) within mineral oil is described. The resulting electrode shows an excellent electrocatalytic activity toward ascorbic acid, uric acid, dopamine, 3,4-dihydroxyphenylacetic acid (dopac) and hydrogen peroxide. These properties permit an important decrease in the overvoltage for the oxidation of ascorbic acid (230 mV), uric acid

Mar??a D Rubianes; Gustavo A Rivas

2003-01-01

92

Carbon nanotube field emitter.  

PubMed

Recently, carbon nanotubes (CNTs), possessing excellent properties as field emitters, are attracting considerable attention as electron emitters of a cold cathode. In this review article, field emission phenomena of carbon nanotubes with various morphologies and surfaces (clean surface or adsorbed molecules on it) revealed by field emission microscopy are first described. Then, the main subject of this article, application of CNTs as electron sources in display devices is reviewed. Other electric devices utilizing CNT-field emitters are also presented. PMID:12908229

Saito, Yahachi

2003-01-01

93

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

94

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

PubMed Central

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

2014-01-01

95

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

96

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

PubMed

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

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

2014-01-01

97

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

98

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

99

The Preparation of Carbon Nanotubes  

Microsoft Academic Search

Carbon nanotubes were prepared by dc arc-discharge evaporation of graphite rods, by varying the pressure and the kind of atmospheric gas. Nanotubes, included in the carbon deposit on the cathode, were observed by scanning electron microscopy (SEM).

Yoshinori Ando

1994-01-01

100

Theoretical Study of Iron Filled Carbon Nanotubes  

Microsoft Academic Search

We have investigated, using ab-initio methods, the geometry and magnetic structure of free standing and encapsulated iron nanowires, both in perfect and defective single wall carbon nanotubes. The geometries adopted consist of two layers of iron atoms per unit cell, arranged in hcp(0001) and bcc(011) structures, repeated periodically along the wire axis, When the ratio of the nanowire to nanotube

Mariana Weissmann; Griselda Garcia; Miguel Kiwi; Ricardo Ramirez; Chu-Chun Fu

2006-01-01

101

Magnetic entrapment for fast, simple and reversible electrode modification with carbon nanotubes: Application to dopamine detection  

Microsoft Academic Search

Carbon nanotubes (CNT) have been exploited for an important number of electroanalytical and sensing purposes. Specifically, CNT incorporation to an electrode surface coating increases its roughness and area, provides electrocatalytic activity towards a variety of molecules, and improves electron transfer. This modification is generally based on the irreversible deposition of CNT on surface. Nevertheless, CNT are highly porous materials that

Eva Baldrich; Rodrigo Gómez; Gemma Gabriel; Francesc Xavier Muñoz

2011-01-01

102

Carbon Nanotubes for Supercapacitor  

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

103

Carbon Nanotubes for Supercapacitor  

PubMed Central

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

2010-01-01

104

Carbon nanotube applications in microelectronics  

Microsoft Academic Search

The extraordinary characteristics of carbon nanotubes make them a promising candidate for applications in microelectronics. Catalyst-mediated chemical vapor deposition growth is very well suited for selective in-situ growth of nanotubes compatible with the requirements of microelectronics technology. This deposition method can be exploited for carbon nanotube vias. Semiconducting single-walled tubes can be successfully operated as carbon nanotube field effect transistors

Wolfgang Hoenlein; Franz Kreupl; Georg Stefan Duesberg; Andrew Peter Graham; Maik Liebau; Robert Viktor Seidel; Eugen Unger

2004-01-01

105

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

106

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

PubMed

We report synthesis of a highly versatile multicomponent nanosystem by covalently decorating the surface of multiwalled carbon nanotubes (CNTs) by magnetite nanoparticles (Fe(3)O(4)), poly(ethylene glycol) (PEG), and fluorophore fluorescein isothiocyanate (FITC). The resulting Fe(3)O(4)-PEG-FITC-CNT nanosystem demonstrates high dispersion ability in an aqueous medium, magnetic responsiveness, and fluorescent capacity. Transmission electron microscopy images revealed that Fe(3)O(4) nanoparticles were well anchored onto the surfaces of the CNT. In vitro time kinetic experiments using confocal microscopy demonstrated a higher uptake of the Fe(3)O(4)-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 Fe(3)O(4)-PEG-FITC-CNT nanosystem an ideal candidate for bioimaging, both in vitro and in vivo. PMID:22170574

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

2012-02-01

107

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

108

Metal-coated carbon nanotube tips for scanning probe microscopy  

NASA Astrophysics Data System (ADS)

Metal coating has been introduced in order to improve the resolution and capabilities of carbon nanotube scanning probe microscopy tips. We demonstrate magnetic force microscopy of magnetic recording tracks using Co coated nanotube tips. The resolution achieved is better than 20 nanometers. We also use Au coated nanotube tips to perform electrostatic force microscopy of a cut single nanotube with a narrow gap. The metal coating on nanotubes is found to enable the use of micrometers long nanotubes as scanning probes for topographic imaging of high aspect ratio structures. The metal-coated nanotube tips are shown to significantly decrease the convolution effects from the pyramidal silicon tip in these force microscopy techniques.

Yenilmez, Erhan

2005-03-01

109

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

110

Carbon nanotube filters  

NASA Astrophysics Data System (ADS)

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

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

2004-09-01

111

Novel composite of Co\\/carbon nanotubes: Synthesis, magnetism and microwave absorption properties  

Microsoft Academic Search

Composites of flowery hexagonal close-packed (hcp) cobalt crystallite covered with multi-wall carbon nanotubes (MWCNTs) were fabricated in high yield via a simple catalytic pyrolysis method. A series of characterizations including X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) revealed that MWCNTs grew on the surface of the cobalt flowers, which possibly followed a bottom-growth model.

Zhong Zheng; B. Xu; L. Huang; L. He; Xiaomin Ni

2008-01-01

112

Carbon Nanotubes - Polymer Composites with Enhanced Conductivity using Functionalized Nanotubes  

Microsoft Academic Search

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

Rajagopal Ramasubramaniam; Jian Chen; Rishi Gupta

2003-01-01

113

Superhydrophobic amorphous carbon/carbon nanotube nanocomposites  

NASA Astrophysics Data System (ADS)

Superhydrophobic amorphous carbon/carbon nanotube nanocomposites are fabricated by plasma immersion ion implantation with carbon nanotube forests as a template. The microstructure of the fabricated nanocomposites shows arrays of carbon nanotubes capped with amorphous carbon nanoparticles. Contact angle measurements show that both advancing and receding angles close to 180° can be achieved on the nanocomposites. The fabrication here does not require patterning of carbon nanotubes or deposition of conformal coatings with low surface energy, which are usually involved in conventional approaches for superhydrophobic surfaces. The relationship between the observed superhydrophobicity and the unique microstructure of the nanocomposites is discussed.

Han, Z. J.; Tay, B. K.; Shakerzadeh, M.; Ostrikov, K.

2009-06-01

114

Purification of Carbon Nanotubes: Alternative Methods  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

115

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

116

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

PubMed

In this work, magnetic multiwalled carbon nanotubes were synthesized through a facile hydrothermal process, and then successfully used as magnetic solid-phase extraction sorbents for the determination of p-hydroxybenzoates in beverage. The prepared magnetic multiwalled carbon nanotubes presented both satisfactory superparamagnetism and strong capacity of absorption, with magnetic Fe(3)O(4) beads of 200 nm average diameters decorated at either ends of the tubes. The hybrid nanocomposites showed a high efficiency in the extraction and enrichment of p-hydroxybenzoates via ?-? stacking of targeted molecules onto the polyaromatic composed surface of multiwalled carbon nanotubes, which entitled them promising magnetic solid-phase extraction sorbents for p-hydroxybenzoates at trace level from complex drink samples. By using an external magnetic field, p-hydroxybenzoates adsorbed on magnetic multiwalled carbon nanotubes could be rapidly isolated in only 30 s, and subsequently analyzed by liquid chromatography-diode array detector after elution with organic solvents. Extraction conditions such as eluting solvent, the amounts of magnetic sorbents added, pH values, adsorption and desorption time were investigated and optimized to achieve the best effect. Method validations including linearity, detection limit, and precision were also studied. The linearities were in the wide range of 0.05-500 ?g/mL with correlation coefficients higher than 0.9983 for all p-hydroxybenzoates. The limits of detection were less than 20 ng/mL. Acceptable RSDs were achieved within 5-8% for all analytes. The results indicated that the proposed method based on magnetic multiwalled carbon nanotubes as magnetic solid-phase extraction absorbents was rapid, efficient, and convenient for the analysis of the targeted compounds of p-hydroxybenzoates in beverage sample. PMID:22761146

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

2012-07-01

117

Magnetic Properties of Edge States in Nanographite Ribbons and Carbon Nanotubes: Density-Matrix Renormalization-Group Study  

NASA Astrophysics Data System (ADS)

Magnetic properties of nanographite ribbons (NGRs) with zigzag and armchair edges are investigated. A ?-electron network in a NGR with zigzag edges exhibits strongly localized edge states, which form almost flat bands at the Fermi energy. Since the flat bands are unstable against the perturbation of electron-electron interactions, there is a possibility that a magnetic polarization appears in the edges. Further it is also an interesting problem if this magnetic behavior is a general feature of zigzag edges of nano-scale carbons such as nanotubes. In this work, we calculate the spin polarization and various correlation functions in NGRs using the density-matrix renormalization-group method, which allows us to obtain high-precision results even in the presence of electron-electron couplings. We show that effective spins grow around the edge sites in the zigzag NGRs while such a growth of effective spins is not observed in the armchair NGRs. We also discuss the appearance of spin polarization in edges of carbon nanotubes.

Hikihara, Toshiya; Hu, Xiao

2002-03-01

118

Adsorption on the carbon nanotubes  

Microsoft Academic Search

Adsorption on single walled carbon nanotubes (SWCNTs) is a subject of growing experimental and theoretical interest. The possible\\u000a adsorbed patterns of atoms and molecules on the single-walled carbon nanotubes vary with the diameters and chirality of the\\u000a tubes due to the confinement. The curvature of the carbon nanotube surface enlarges the distance of the adsorbate atoms and\\u000a thus enhances the

Yi Ding; Xiao-Bao Yang; Jun Ni

2006-01-01

119

Method of manufacturing carbon nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

120

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

121

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

122

Carbon nanotube core graphitic shell hybrid fibers.  

PubMed

A carbon nanotube yarn core graphitic shell hybrid fiber was fabricated via facile heat treatment of epoxy-based negative photoresist (SU-8) on carbon nanotube yarn. The effective encapsulation of carbon nanotube yarn in carbon fiber and a glassy carbon outer shell determines their physical properties. The higher electrical conductivity (than carbon fiber) of the carbon nanotube yarn overcomes the drawbacks of carbon fiber/glassy carbon, and the better properties (than carbon nanotubes) of the carbon fiber/glassy carbon make up for the lower thermal and mechanical properties of the carbon nanotube yarn via synergistic hybridization without any chemical doping and additional processes. PMID:24224730

Hahm, Myung Gwan; Lee, Jae-Hwang; Hart, Amelia H C; Song, Sung Moo; Nam, Jaewook; Jung, Hyun Young; Hashim, Daniel Paul; Li, Bo; Narayanan, Tharangattu N; Park, Chi-Dong; Zhao, Yao; Vajtai, Robert; Kim, Yoong Ahm; Hayashi, Takuya; Ku, Bon-Cheol; Endo, Morinobu; Barrera, Enrique; Jung, Yung Joon; Thomas, Edwin L; Ajayan, Pulickel M

2013-12-23

123

Carbon nanotubes analysis, classification and characterization  

Microsoft Academic Search

Different nanostructures, electronic nanodevices, nanoresonators, nanoswitches and other devices have been devised, designed and fabricated using carbon nanotubes. Carbon nanotubes are among the promising carbon-based solutions that have been attracted a significant attention in last years. This paper examines important problems in carbon nanotubes analysis, classification and characterization using experimental data. In particular, we classify carbon nanotubes as metallic, semimetallic

M. A. Lyshevski

2004-01-01

124

Carbon nanotubes: opportunities and challenges  

Microsoft Academic Search

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

Hongjie Dai

2002-01-01

125

Half-metallic carbon nanotubes.  

PubMed

Half-metallicity in carbon nanotubes is achieved and controlled by hydrogen adsorption patterns. The edge states in carbon nanotubes are unstable under an electric field due to the spin-conserving electron transfer between the edges, but a large enough transfer barrier between the edge states, obtained by controlling the adsorption patterns, renders the CNTs half-metallic. PMID:22419361

Lee, Kyu Won; Lee, Cheol Eui

2012-04-17

126

Carbon Nanotube Nucleated Polymer Crystallization  

Microsoft Academic Search

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

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

2005-01-01

127

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...

128

Quantum Transport in Carbon Nanotubes  

Microsoft Academic Search

We present a tutorial introduction into the structure and electronic properties of carbon nanotubes which may serve as an\\u000a entry point into the literature on the field. Some of the original experiments in the field are selected to illustrate the\\u000a richness of quantum transport in single-and multi-wall carbon nanotubes.

Elsa Thune; Christoph Strunk

2005-01-01

129

Carbon nanotube yarn strain sensors  

Microsoft Academic Search

Carbon nanotube (CNT) based sensors are often fabricated by dispersing CNTs into different types of polymer. In this paper, a prototype carbon nanotube (CNT) yarn strain sensor with excellent repeatability and stability for in situ structural health monitoring was developed. The CNT yarn was spun directly from CNT arrays, and its electrical resistance increased linearly with tensile strain, making it

Haibo Zhao; Yingying Zhang; Philip D. Bradford; Qian Zhou; Quanxi Jia; Fuh-Gwo Yuan; Yuntian Zhu

2010-01-01

130

Threshold-like features in the magnetic response of iron-filled multi-walled carbon nanotube and polymer composite  

NASA Astrophysics Data System (ADS)

The magnetic properties of iron-filled multi-walled carbon nanotubes dispersed in polystyrene (Fe-MWNT/PS) have been investigated as a function of Fe-MWNT concentration (0.1-15 wt%) from 300 to 10 K. Electron microscopy studies indicate that Fe nanorods (aspect ratio ~5) remain trapped at various lengths of MWNT and are thus, prevented from oxidation as well as aggregation. The magnetization versus applied field (M-H loop) data of 0.1 wt% of Fe-MWNTs in PS show an anomalous narrowing at low temperatures which is due to the significant contribution from shape anisotropy of Fe nanorods. The remanence shows a threshold feature at 1 wt%. The enhanced coercivity shows a maximum at 1 wt% due to the dominant dipolar interactions among Fe nanorods. Also the squareness ratio shows a maximum at 1 wt%.

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

2011-10-01

131

Superconducting properties of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Metallic single wall carbon nanotubes have attracted much 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 an insulating behavior 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 with supercurrents which strongly depend on the transmission of the electrodes. On the other hand intrinsic superconductivity was also observed in suspended ropes of carbon nanotubes and recently in doped individual tubes. These experiments indicate the presence of attractive interactions in carbon nanotubes which overcome Coulomb repulsion at low temperature, and enables investigation of superconductivity in a 1D limit never explored before. To cite this article: M. Ferrier et al., C. R. Physique 10 (2009).

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

2009-05-01

132

Studies of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

Caneba, Gerard T.

2005-01-01

133

Carbon Nanotube Interconnect  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

134

Silicon Encapsulated Carbon Nanotubes  

PubMed Central

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

2010-01-01

135

Carbon-Nanotube Optoelectronics  

Microsoft Academic Search

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

Phaedon Avouris; Marcus Freitag; Vasili Perebeinos

136

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

PubMed

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

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

2011-09-01

137

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

138

Polymer nanocomposites based on functionalized carbon nanotubes  

Microsoft Academic Search

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

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

2010-01-01

139

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

140

Controllable synthesis, characterization and microwave absorption properties of magnetic Ni1-xCoxP alloy nanoparticles attached on carbon nanotubes  

Microsoft Academic Search

Ni1-xCox alloy nanoparticles (x = 0.25, 0.50, 0.75), with diameters in the range 8-18 nm were uniformly attached on the surface of multi-walled carbon nanotubes (MWNTs) by electroless plating, and were characterized by transmission electron microscopy, energy-dispersive x-ray spectrometry, x-ray diffraction analysis, vibrating sample magnetometry and vector network analysis. Magnetization measurement indicates that both coercivities and saturation magnetizations decreased linearly

Yongjie Li; Cunzhen Zhu; Chunming Wang

2008-01-01

141

Feasibility of Magnetically Functionalised Carbon Nanotubes for Biological Applications: From Fundamental Properties of Individual Nanomagnets to Nanoscaled Heaters and Temperature Sensors  

Microsoft Academic Search

\\u000a We discuss the prospects of applying the magnetic properties of magnetically functionalised carbon nanotubes to biomedical\\u000a applications. The primary applications are use as a contactless local heating agent, as a standalone thermoablation treatment\\u000a or in concert with remotely released anti-cancer drugs. Targeted heat treatment is an effective cancer treatment, as tumour\\u000a tissue has a reduced heat tolerance. To understand the

Matthias U. Lutz; Kamil Lipert; Yulia Krupskaya; Stefan Bahr; Anja Wolter; Ahmed A. El-Gendy; Silke Hampel; Albrecht Leonhardt; Arthur Taylor; Kai Krämer; Bernd Büchner; Rüdiger Klingeler

142

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

143

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

144

Method for producing carbon nanotubes  

DOEpatents

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

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

2006-02-14

145

Carbon fibers modified with carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes were used to modify a polyacrylonitrile (PAN) polymer solution before the manufacture of the carbon fiber\\u000a precursor. The modified PAN fibers were spun from a dimethylformamide solution containing a small amount of single-walled\\u000a carbon nanotubes. The fibers were characterized by thermogravimetry and optical and scanning electron microscopy. Structure,\\u000a morphology, and selected properties of the composite polymeric fibers and

Aneta Fraczek-Szczypta; Maciej Bogun; Stanislaw Blazewicz

2009-01-01

146

Suspended Carbon Nanotube Field Effect Transistor.  

National Technical Information Service (NTIS)

The invention provides a carbon nanotube field effect transistor including a nanotube having a length suspended between source and drain electrodes. A gate dielectric material coaxially coats the suspended nanotube length and at least a portion of the sou...

H. Peng J. A. Golovchenko

2005-01-01

147

Torsional Electromechanics of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

148

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

149

Carbon Nanotubes as Thermionic Emitters  

NASA Astrophysics Data System (ADS)

Thermionic converters are an interesting option for lightweight and long-life power generators due to a number of compelling advantages, including all solid construction, no moving parts, and waste heat rejection at high temperature. An experimental set up has been built that allows the screening of thermionic coatings and new nanomaterials from room temperature to 2000 K in high vacuum and at gap sizes as small as 1 ?m. A new class of very high temperature compatible materials, carbon nanotubes, has been investigated for their performance as cathodes. Seven different types of carbon nanotubes have been screened as thermionic emitter cathodes and compared to tungsten and nitrogen doped diamond. It has been found that some carbon nanotubes combine excellent temperature stability with good thermal emission performance. Yet, other carbon nanotubes exhibited exceptional combined thermal and field enhanced emission performance.

Loutfy, R. O.; Samandi, M.; Moravsky, A.; Strange, S.

2004-02-01

150

Carbon nanotube electronics \\/ Électronique à nanotubes de carbone Multiscale simulation of carbon nanotube devices  

Microsoft Academic Search

In recent years, the understanding and accurate simulation of carbon nanotube-based devices has become very challenging. Conventional simulation tools of microelectronics are necessary to envision the performance and use of nanotube transistors and circuits, but the models need to be refined to properly describe the full complexity of such novel type of devices at the nanoscale. Indeed, many issues such

C. Adessi; R. Avriller; A. Bournel; H. Cazin; P. Dollfusc; S. Frégonèse; S. Galdin-Retailleau; A. López-Bezanilla; C. Maneux; H. Nha Nguyen; D. Querlioz; S. Rochee; F. Triozon; T. Zimmer

151

Cantilevered carbon nanotube hygrometer  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

152

Carbon nanotube electron gun  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

153

Carbon nanotube terahertz detector.  

PubMed

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

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

2014-07-01

154

Dispersible carbon nanotubes.  

PubMed

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

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

2014-01-27

155

Selective functionalization of carbon nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

156

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

157

PECVD Growth of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

158

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

159

Polysaccharide-carbon nanotube complex  

US Patent & Trademark Office Database

Disclosed is a complex which comprises a carbon nanotube and a modified polysaccharide having a backbone chain with the side thereof being introduced with monosaccharide or oligosaccharide residues. The polysaccharide is preferably .beta.-1,3-glucan. The complex is prepared by admixing a solution of the modified polysaccharide dissolved in an aprotic polar solvent or a strong alkali solution with an aqueous dispersion of the carbon nanotube, and incubating the mixture.

2011-05-03

160

Nanotechnology with Carbon Nanotubes: Mechanics, Chemistry, and Electronics  

NASA Technical Reports Server (NTRS)

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

Srivastava, Deepak

2003-01-01

161

Supersymmetric twisting of carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

Jakubský, Vít; Plyushchay, Mikhail S.

2012-02-01

162

Carbon nanotubes in scaffolds for tissue engineering.  

PubMed

Carbon nanotubes are hollow graphitic cylinders of nanoscale dimensions. They are electrically conductive, chemically and thermally stable, and exceptionally strong. Given this unique combination of properties there has been much interest in carbon nanotubes, and finding applications for them. One application where this combination of properties may prove useful is in the area of tissue regeneration, incorporating carbon nanotubes into scaffolds for tissue engineering. It is believed that carbon nanotubes may improve scaffold properties and enhance tissue regeneration. This report aims to discuss the suitability of carbon nanotubes as a biomaterial for scaffold production, and the fabrication, properties and performance of carbon nanotube-based scaffolds. PMID:19751122

Edwards, Sharon L; Werkmeister, Jerome A; Ramshaw, John A M

2009-09-01

163

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

SciTech Connect

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

Zhang, Yi, E-mail: zhangyi520love@yahoo.com.cn [Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi’an 710072 (China)] [Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi’an 710072 (China); Qi, Shuhua; Zhang, Fan [Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi’an 710072 (China)] [Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi’an 710072 (China)

2012-11-15

164

Carbon nanostraws: nanotubes filled with superparamagnetic nanoparticles.  

PubMed

A two-step magnetically assisted capillary action method is demonstrated as a facile technique to produce hollow carbon nanotubes filled with uniformly dispersed Fe3O4 nanoparticles (NPs). Template-assisted chemical vapor deposition (CVD) grown CNTs with average diameter 200-300 nm and length 5-6 microm were effectively used as 'nanostraws' to suck in chemically synthesized Fe3O4 nanoparticles (mean size approximately 6 nm) in a ferrofluid suspension. Temperature and magnetic field-dependent DC magnetization measurements indicate that these functionalized nanotubes are superparamagnetic at room temperature with enhanced interparticle interactions due to the close packing of the nanoparticles within the tubes. Magnetic relaxation phenomena in these filled nanotubes are probed using frequency-dependent AC susceptibility. The reasonably large saturation magnetization (M(s) = 65 emu g(-1)) attained in these nanostructures makes them very promising for a diverse set of applications that utilize both the magnetic and dielectric functionalities of these composite nanotube materials. PMID:19880982

Pal, Susmita; Chandra, Sayan; Phan, Manh-Huong; Mukherjee, Pritish; Srikanth, Hariharan

2009-12-01

165

Carbon Nanotube Purification  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

166

Helicity of Carbon Nanotubes and Helix-shaped Carbon Nanotubes  

Microsoft Academic Search

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

Ji-Peng Cheng; Xiao-Bin Zhang

2006-01-01

167

The chemistry and application of carbon nanotubes  

Microsoft Academic Search

The review concerns the main chemical and physicochemical properties and the methods of modification of carbon nanotubes, a novel promising material. The feasible and potential fields of applications of carbon nanotubes are outlined. The bibliography includes 573 references.

Eduard G Rakov

2001-01-01

168

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

PubMed

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

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

2014-02-15

169

Carbon Nanotube Based Molecular Electronics  

NASA Technical Reports Server (NTRS)

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

Srivastava, Deepak; Saini, Subhash; Menon, Madhu

1998-01-01

170

Removal of some impurities from carbon nanotubes  

NASA Astrophysics Data System (ADS)

A non-destructive mild oxidation method of removing some impurities from as-grown carbon nanotubes (CNTs), including single-wall carbon nanotubes (SWNTs) and multi-wall carbon nanotubes (MWNTs), by H 2O 2 oxidation and HCl treatment, has been investigated, and somewhat pure carbon nanotubes have been prepared. The CNTs from which some impurities were removed have been evaluated by transmission electron microscopy (TEM) and temperature programmed oxidation and gas chromatography (TPO-GC).

Feng, Yongcheng; Zhou, Gumin; Wang, Guoping; Qu, Meizhen; Yu, Zuolong

2003-07-01

171

Multiscale Modeling with Carbon Nanotubes  

SciTech Connect

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

Maiti, A

2006-02-21

172

Carbon nanotubes hybrid hydrogels in drug delivery: a perspective review.  

PubMed

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

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

2014-01-01

173

Carbon Nanotubes Hybrid Hydrogels in Drug Delivery: A Perspective Review  

PubMed Central

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

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

2014-01-01

174

Ultrasensitive magnetometers based on carbon-nanotube mechanical resonators.  

PubMed

We describe herein how a nanoelectromechanical system based on a carbon nanotube used as a force sensor can enable one to assess the magnetic properties of a single and very small nano-object grafted onto the nanotube. Numerical simulations performed within the framework of the Euler-Bernoulli theory of beams predict that the magnetic field dependence of the nanotube mechanical resonance frequency is a direct probe for the nano-object magnetic properties and that a sensitivity around a few (few hundreds) Bohr magnetic moments at low temperature (room temperature) can be expected. PMID:22026835

Lassagne, B; Ugnati, D; Respaud, M

2011-09-23

175

Dispersions of Carbon nanotubes in Polymer Matrices  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

176

Carbon molecules oscillating in carbon nanotube bundles  

Microsoft Academic Search

Fullerenes C60 and carbon nanotubes are of considerable interest to researchers from many scientific areas due to their unique electronic and mechanical properties. One application of these carbon nanostructures that has recently attracted much attention is the creation of an oscillator that operates in the gigahertz range frequency. A number of studies have found that the sliding of the inner-shell

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

2008-01-01

177

Structural transformations of carbon chains inside nanotubes  

SciTech Connect

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

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

2010-04-15

178

Epoxide composite materials with carbon nanotubes  

NASA Astrophysics Data System (ADS)

Methods of formation and physical properties of epoxide composite materials reinforced with carbon nanotubes are considered. An analogy is made between the relaxation properties of carbon nanotubes and macromolecules. The concentration dependences of the electrical conductivity of the epoxy polymers filled with single-walled and multi-walled carbon nanotubes are discussed. Modern views on the mechanism of reinforcement of polymers with nanotubes are outlined. The bibliography includes 143 references.

Irzhak, Vadim I.

2011-08-01

179

Polymerization of conducting polymers inside carbon nanotubes  

NASA Astrophysics Data System (ADS)

Supercritical carbon dioxide is an universal tool to impregnate carbon nanotubes with a wide range of organic molecules. In this Letter, we present our results of carbon nanotubes filled with the photo-conducting polymer poly( N-vinyl carbazole) and the conducting polymer polypyrrole which were prepared by polymerizing the monomers inside the nanotubes. The endohedral nanotubes were characterized by HRTEM and 1H NMR which confirmed that the encapsulated material was indeed the conducting polymer.

Steinmetz, Johannes; Kwon, Soyoung; Lee, Hyun-Jung; Abou-Hamad, Edy; Almairac, Robert; Goze-Bac, Christophe; Kim, Hwayong; Park, Yung-Woo

2006-11-01

180

Gears Based on Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

Gears based on carbon nanotubes (see figure) have been proposed as components of an emerging generation of molecular- scale machines and sensors. In comparison with previously proposed nanogears based on diamondoid and fullerene molecules, the nanotube-based gears would have simpler structures and are more likely to be realizable by practical fabrication processes. The impetus for the practical development of carbon-nanotube- based gears arises, in part, from rapid recent progress in the fabrication of carbon nanotubes with prescribed diameters, lengths, chiralities, and numbers of concentric shells. The shafts of the proposed gears would be made from multiwalled carbon nanotubes. The gear teeth would be rigid molecules (typically, benzyne molecules), bonded to the nanotube shafts at atomically precise positions. For fabrication, it may be possible to position the molecular teeth by use of scanning tunneling microscopy (STM) or other related techniques. The capability to position individual organic molecules at room temperature by use of an STM tip has already been demonstrated. Routes to the chemical synthesis of carbon-nanotube-based gears are also under investigation. Chemical and physical aspects of the synthesis of molecular scale gears based on carbon nanotubes and related molecules, and dynamical properties of nanotube- based gears, have been investigated by computational simulations using established methods of quantum chemistry and molecular dynamics. Several particularly interesting and useful conclusions have been drawn from the dynamical simulations performed thus far: The forces acting on the gears would be more sensitive to local molecular motions than to gross mechanical motions of the overall gears. Although no breakage of teeth or of chemical bonds is expected at temperatures up to at least 3,000 K, the gears would not work well at temperatures above a critical range from about 600 to about 1,000 K. Gear temperature could probably be controlled by use of coolant gases. For a given application, the gears would work well at temperatures below the critical range, provided that the rotational energy was less than the energy required to tilt the teeth through an angle of 20 . The predominant mechanism of gear failure would be slippage caused by tilting of teeth. Gears would resume functioning if the slipping gears were decelerated sufficiently.

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

2005-01-01

181

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

182

Carbon nanotube yarn strain sensors  

NASA Astrophysics Data System (ADS)

Carbon nanotube (CNT) based sensors are often fabricated by dispersing CNTs into different types of polymer. In this paper, a prototype carbon nanotube (CNT) yarn strain sensor with excellent repeatability and stability for in situ structural health monitoring was developed. The CNT yarn was spun directly from CNT arrays, and its electrical resistance increased linearly with tensile strain, making it an ideal strain sensor. It showed consistent piezoresistive behavior under repetitive straining and unloading, and good resistance stability at temperatures ranging from 77 to 373 K. The sensors can be easily embedded into composite structures with minimal invasiveness and weight penalty. We have also demonstrated their ability to monitor crack initiation and propagation.

Zhao, Haibo; Zhang, Yingying; Bradford, Philip D.; Zhou, Qian; Jia, Quanxi; Yuan, Fuh-Gwo; Zhu, Yuntian

2010-07-01

183

Formation of ice nanotube with hydrophobic guests inside carbon nanotube.  

PubMed

A composite ice nanotube inside a carbon nanotube has been explored by molecular-dynamics and grand canonical Monte Carlo simulations. It is made from an octagonal ice nanotube whose hollow space contains hydrophobic guest molecules such as neon, argon, and methane. It is shown that the attractive interaction of the guest molecules stabilizes the ice nanotube. The guest occupancy of the hollow space is calculated by the same method as applied to clathrate hydrates. PMID:16164361

Tanaka, Hideki; Koga, Kenichiro

2005-09-01

184

Junction array carbon nanotube bolometer  

NASA Astrophysics Data System (ADS)

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

Kozlov, Mikhail E.

2013-04-01

185

Carbon Nanotube Material Quality Assessment  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

186

Plasma CVD of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

187

Supported lipid bilayer/carbon nanotube hybrids.  

PubMed

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. PMID:18654251

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

2007-03-01

188

An anticorrosive magnesium\\/carbon nanotube composite  

Microsoft Academic Search

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

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

2008-01-01

189

Conductance Oscillations in Squashed Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

190

Sugar coated stealth carbon nanotubes  

Microsoft Academic Search

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

Nalinikanth Kotagiri; Jin-Woo Kim

2010-01-01

191

Carbon Nanotube Based Light Sensor.  

National Technical Information Service (NTIS)

A light sensor substrate comprises a base made from a semi-conductive material and topped with a layer of an electrically non-conductive material. A first electrode and a plurality of carbon nanotube (CNT)-based conductors are positioned on the layer of e...

A. N. Watkins J. D. Jordan J. L. Ingram J. M. Smits R. A. Wincheski

2004-01-01

192

Terahertz detection and carbon nanotubes  

ScienceCinema

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

Leonard, Francois

2014-06-13

193

Aligned carbon nanotubes for nanoelectronics  

Microsoft Academic Search

We discuss the central issues to be addressed for realizing carbon nanotube (CNT) nanoelectronics. We focus on selective growth, electron energy bandgap engineering and device integration. We have introduced a nanotemplate to control the selective growth, length and diameter of CNTs. Vertically aligned CNTs are synthesized for developing a vertical CNT-field effect transistor (FET). The ohmic contact of the CNT\\/metal

Won Bong Choi; Eunju Bae; Donghun Kang; Soodoo Chae; Byung-ho Cheong; Ju-hye Ko; Eungmin Lee; Wanjun Park

2004-01-01

194

Electrophoretic deposition of carbon nanotubes  

Microsoft Academic Search

Electrophoretic deposition (EPD) has been gaining increasing interest as an economical and versatile processing technique for the production of novel coatings or films of carbon nanotubes (CNTs) on conductive substrates. The purpose of the paper is to present an up-to-date comprehensive overview of current research progress in the field of EPD of CNTs. The paper specifically reviews the preparation and

Aldo R. Boccaccini; Johann Cho; Judith A. Roether; Boris J. C. Thomas; E. Jane Minay; Milo S. P. Shaffer

2006-01-01

195

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

196

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

197

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

PubMed

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

Du, Zhuo; Liu, Miao; Li, Gongke

2013-10-01

198

Peel test of spinnable carbon nanotube webs  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

199

Structure and energetics of carbon nanotube ropes  

Microsoft Academic Search

High-resolution electron microscopy observation and energetic analysis have been performed on ropes formed from single-walled carbon nanotubes. When individual nanotubes are twisted, the nanotube ropes become energetically stable—a configuration that also offers better structural stability. Electron microscopic image simulations of an energetically-stable rope composed of seven single-walled carbon nanotubes have been carried out as well to elaborate the salient features

Zejian Liu; Lu-Chang Qin

2005-01-01

200

Probing Mechanical Properties of Carbon Nanotubes by Light Scattering  

NASA Astrophysics Data System (ADS)

An important capability for studying and exploiting the remarkable mechanical properties of carbon nanotubes is the detection of their physical motion. Here we present a scheme based on light scattering by a nanotube placed slightly off-center of a tightly focused laser beam. The approach permits measurement of the movement of individual single-walled carbon nanotubes with nanometer sensitivity and high detection bandwidth. The method can be readily combined with optical characterization by Rayleigh scattering spectroscopy for studies of well-defined nanotube structures [1]. The technique is demonstrated for suspended pristine nanotubes, as well as for nanotubes modified by mass loading. By passing a current through the nanotube in the presence of a magnetic field, we can apply static and oscillating Lorentz forces. In this fashion, we have produced both static deflection and vibration excitation of nanotubes. Sharply defined nanotube vibrational modes are observed by sweeping the frequency of the driving force. We discuss the nature of these resonances and how to extract fundamental nanotube properties from the measurements. [1] M. Y. Sfeir, Science 306, 1540 (2004).

Wu, Yang; Wang, Feng; Huang, Mingyuan; Huang, Limin; Sfeir, Matthew Y.; Brus, Louis E.; O'Brien, Stephen; Hone, James; Heinz, Tony F.

2006-03-01

201

From carbon nanotubes to carbon atomic chains  

NASA Astrophysics Data System (ADS)

Carbyne is a linear allotrope of carbon. It is formed by a linear arrangement of carbon atoms with sp-hybridization. We present a reliable and reproducible experiment to obtain these carbon atomic chains using few-layer-graphene (FLG) sheets and a HRTEM. First the FLG sheets were synthesized from worm-like exfoliated graphite and then drop-casted on a lacey-carbon copper grid. Once in the TEM, two holes are opened near each other in a FLG sheet by focusing the electron beam into a small spot. Due to the radiation, the carbon atoms rearrange themselves between the two holes and form carbon fibers. The beam is concentrated on the carbon fibers in order excite the atoms and induce a tension until multi wall carbon nanotube (MWCNT) is formed. As the radiation continues the MWCNT breaks down until there is only a single wall carbon nanotube (SWCNT). Then, when the SWCNT breaks, an atomic carbon chain is formed, lasts for several seconds under the radiation and finally breaks. This demonstrates the stability of this carbon structure.

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

2010-10-01

202

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

PubMed

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

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

2014-06-01

203

Carbon-Nanotube Schottky Diodes  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

204

Mechanics of Carbon Nanotubes and their Polymer Composites.  

National Technical Information Service (NTIS)

Contents include the folloving: carbon nanotube (CNT): structures, application of carbon nanotubes, simulation method, Elastic properties of carbon nanotubes, yield strain of CNT, yielding under tensile stress, yielding: strain-rate and temperature depend...

C. Wei K. J. Cho D. Srivastava

2002-01-01

205

Aharonov-Bohm conductance modulation in ballistic carbon nanotubes.  

PubMed

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

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

2007-04-27

206

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

207

Carbon Nanotubes - Towards Artificial Nose Implementation  

Microsoft Academic Search

Functionalization of multiwall carbon nanotubes (MWCNTs) allows the outer wall of the nanotubes to be turned into chemically selective surfaces. As in the electric transport along the nanotube axis the outer wall plays a dominant role, the modulation of this transport lends itself to direct application in gas sensing. In our work the modification of electrical conduction was used as

A. A. Koos; K. Kertesz; M. Adam; C. Ducso; Z. E. Horvath; L. P. Biro; I. Barsony; J. Gyulai; Z. Konya; I. Kiricsi

2006-01-01

208

Electron transport properties of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Electrical resistivity measurements of bulk samples of carbon nanotubes show that the resistivity behaviour of nanotubes is comparable to that of graphite. Thermopower behaviour of nanotubes is similar to that of certain pyrolytic graphites. Tunneling conductance measurements on isolated tubes however show the existence of a conductance gap which increases with the inverse diameter of the tube.

Seshadri, Ram; Aiyer, Hemantkumar N.; Govindaraj, A.; Rao, C. N. R.

1994-07-01

209

A Tester for Carbon Nanotube Mode Lockers  

Microsoft Academic Search

We propose and demonstrate a tester for laser pulsating operation of carbon nanotubes employing a circulator with the extra degree of freedom of the second port to access diversified nanotube samples. The nanotubes are deposited onto the end facet of a dummy optical fiber by spray method that guarantees simple sample loading along with the minimized perturbation of optimized laser

Yong-Won Song; Shinji Yamashita

2007-01-01

210

Raman Studies of Carbon Nanotubes and Polymer Nanotube Composites  

Microsoft Academic Search

In this paper, we present Raman studies of different carbon nanotubes systems like single-walled nanotubes(SWNTs), multi-walled nanotubes(MWNTs)or composites prepared with different conjugated or non-conjugated polymers. We have focused our studies on the interactions that can take place in these systems and in general modify the characteristics of individual tubes. By introducing Van der Waals interactions between tubes, we are able

S. Lefrant; J. P. Buisson; J. Schreiber; O. Chauvet; M. Baibarac; I. Baltog

2004-01-01

211

Trapping Cold Atoms by a Carbon Nanotube  

NASA Astrophysics Data System (ADS)

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

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

212

From carbon nanobells to nickel nanotubes  

SciTech Connect

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

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

2009-01-05

213

Carbon Nanotubes: Molecular Electronic Components  

NASA Technical Reports Server (NTRS)

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

Srivastava, Deepak; Saini, Subhash; Menon, Madhu

1997-01-01

214

Carbon nanotube yarn strain sensors.  

PubMed

Carbon nanotube (CNT) based sensors are often fabricated by dispersing CNTs into different types of polymer. In this paper, a prototype carbon nanotube (CNT) yarn strain sensor with excellent repeatability and stability for in situ structural health monitoring was developed. The CNT yarn was spun directly from CNT arrays, and its electrical resistance increased linearly with tensile strain, making it an ideal strain sensor. It showed consistent piezoresistive behavior under repetitive straining and unloading, and good resistance stability at temperatures ranging from 77 to 373 K. The sensors can be easily embedded into composite structures with minimal invasiveness and weight penalty. We have also demonstrated their ability to monitor crack initiation and propagation. PMID:20610871

Zhao, Haibo; Zhang, Yingying; Bradford, Philip D; Zhou, Qian; Jia, Quanxi; Yuan, Fuh-Gwo; Zhu, Yuntian

2010-07-30

215

Transplanting Assembly of Carbon Nanotubes  

Microsoft Academic Search

The manufacture of nanotechnology products requires assembly of nano scale components to macro\\/micro-scale systems, which is a major challenge in attempting to industrialize nanotechnologies. A new approach to assemble nanostructures is developed with a control of individual nanostructure's location and alignment in a long-range order. A concept of transplanting assembly has been developed to embed carbon nanotubes into micro-scale polymer

S. G. Kim

2006-01-01

216

Polarons in suspended carbon nanotubes.  

PubMed

We prove theoretically the possibility of electric-field controlled polaron formation involving flexural (bending) modes in suspended carbon nanotubes. Upon increasing the field, the ground state of the system with a single extra electron undergoes a first-order phase transition between an extended state and a localized polaron state. For a common experimental setup, the threshold electric field is only of the order of approximately equal 5×10(-2) V/?m. PMID:22401239

Snyman, I; Nazarov, Yu V

2012-02-17

217

Impurity resonances in carbon nanotubes  

NASA Astrophysics Data System (ADS)

Analytical expressions are derived for the self-energies of electrons in carbon nanotubes while interacting with impurity atoms. Results are reported for armchair and zigzag tubes. It is shown that the impurity causes a bound electron donor or acceptor state beneath every semiconductor band edge. If the tubes are metallic, these bound states become resonance states. The analytical formulas give resonance shapes in good agreement with former numerical calculations.

Mahan, G. D.

2004-03-01

218

Logic Circuits with Carbon Nanotube Transistors  

Microsoft Academic Search

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

Adrian Bachtold; Peter Hadley; Takeshi Nakanishi; Cees Dekker

2001-01-01

219

Electroless plating of nickel on carbon nanotubes film  

Microsoft Academic Search

For carbon nanotubes to be used for electronic application, nanotubes would need to achieve high interfacial adhesion with metal. In this paper, chemical vapor deposited carbon nanotubes have been successfully coated with nickel by electroless plating method. Ni plates were used as substrates as well as catalyst provider for the growth of carbon nanotubes. Without dispersing the grown nanotubes from

K. P. Yung; J. Wei; B. K. Tay

2005-01-01

220

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

PubMed

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

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

2014-06-27

221

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

222

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

223

Plasticity and Kinky Chemistry of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

Srivastava, Deepak; Dzegilenko, Fedor

2000-01-01

224

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

PubMed

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

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

2014-08-15

225

Covalent Sidewall Functionalization of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

226

CARBON NANOTUBES: PROPERTIES AND APPLICATIONS  

SciTech Connect

Carbon nanotubes were discovered in 1991 as a minority byproduct of fullerene synthesis. Remarkable progress has been made in the ensuing years, including the discovery of two basic types of nanotubes (single-wall and multi-wall), great strides in synthesis and purification, elucidation of many fundamental physical properties, and important steps towards practical applications. Both the underlying science and technological potential of SWNT can profitably be studied at the scale of individual tubes and on macroscopic assemblies such as fibers. Experiments on single tubes directly reveal many of the predicted quantum confinement and mechanical properties. Semiconductor nanowires have many features in common with nanotubes, and many of the same fundamental and practical issues are in play – quantum confinement and its effect on properties; possible device structures and circuit architectures; thermal management; optimal synthesis, defect morphology and control, etc. In 2000 we began a small effort in this direction, conducted entirely by undergraduates with minimal consumables support from this grant. With DOE-BES approval, this grew into a project in parallel with the carbon nanotube work, in which we studied of inorganic semiconductor nanowire growth, characterization and novel strategies for electronic and electromechanical device fabrication. From the beginnings of research on carbon nanotubes, one of the major applications envisioned was hydrogen storage for fuel-cell powered cars and trucks. Subsequent theoretical models gave mixed results, the most pessimistic indicating that the fundamental H2-SWNT interaction was similar to flat graphite (physisorption) with only modest binding energies implying cryogenic operation at best. New material families with encouraging measured properties have emerged, and materials modeling has gained enormously in predictive power, sophistication, and the ability to treat a realistically representative number of atoms. One of the new materials, highly porous carbide-derived carbons (CDC), is the subject of an add-on to this grant awarded to myself and Taner Yildirim (NIST). Results from the add-on led eventually to a new 3-year award DE-FG02-08ER46522 “From Fundamental Understanding to Predicting New Nanomaterials for High Capacity Hydrogen Storage”, $1000K, (05/31/2008 - 05/01/2011) with Taner Yildirim and myself as co-PI’s.

Fischer, John, E.

2009-07-24

227

Specific surface area of carbon nanotubes and bundles of carbon nanotubes  

Microsoft Academic Search

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

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

2001-01-01

228

Unzipping carbon nanotubes at high impact.  

PubMed

The way nanostructures behave and mechanically respond to high impact collision is a topic of intrigue. For anisotropic nanostructures, such as carbon nanotubes, this response will be complicated based on the impact geometry. Here we report the result of hypervelocity impact of nanotubes against solid targets and show that impact produces a large number of defects in the nanotubes, as well as rapid atom evaporation, leading to their unzipping along the nanotube axis. Fully atomistic reactive molecular dynamics simulations are used to gain further insights of the pathways and deformation and fracture mechanisms of nanotubes under high energy mechanical impact. Carbon nanotubes have been unzipped into graphene nanoribbons before using chemical treatments but here the instability of nanotubes against defect formation, fracture, and unzipping is revealed purely through mechanical impact. PMID:24915176

Ozden, Sehmus; Autreto, Pedro A S; Tiwary, Chandra Sekhar; Khatiwada, Suman; Machado, Leonardo; Galvao, Douglas S; Vajtai, Robert; Barrera, Enrique V; M Ajayan, Pulickel

2014-07-01

229

Polymer Self-assembly on Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

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

Giulianini, Michele; Motta, Nunzio

230

Optical properties of aligned carbon nanotubes  

Microsoft Academic Search

By using a series expression of effective dielectric function ?eff, the optical properties of alpha aligned carbon nanotubes arranged in a square array are investigated. The frequency dependence of the effective dielectric function is studied for various ratios rho (ratio between internal and external radii of carbon nanotube) and x (ratio between the lattice constant and the external radii of

Xuhong Wu; Lunsheng Pan; Hua Li; Xijun Fan; Teng Yong Ng; Diao Xu; Chengxiang Zhang

2003-01-01

231

Doping and phonon renormalization in carbon nanotubes  

Microsoft Academic Search

We show that the Raman frequency associated with the vibrational mode at ~1,580 cm-1 (the G mode) in both metallic and semiconducting carbon nanotubes shifts in response to changes in the charge density induced by an external gate field. These changes in the Raman spectra provide us with a powerful tool for probing local doping in carbon nanotubes in electronic

J. C. Tsang; M. Freitag; V. Perebeinos; J. Liu; Ph. Avouris

2007-01-01

232

Carbon nanotube oscillators for applications as nanothermometers  

Microsoft Academic Search

Nanostructures such as carbon nanotubes have a broad range of potential applications such as nanomotors, nano-oscillators and electromechanical nanothermometers, and a proper understanding of the molecular interaction between nanostructures is fundamentally important for these applications. In this paper, we determine the molecular interaction potential of interacting carbon nanotubes for two configurations. The first is a shuttle configuration involving a short

Fainida Rahmat; Ngamta Thamwattana; James M. Hill

2010-01-01

233

Ophthalmologial Applications of Carbon Nanotube Nanotechology  

NASA Technical Reports Server (NTRS)

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

Loftus, David; Girten, Beverly (Technical Monitor)

2002-01-01

234

Electrospinning carbon nanotube polymer composite nanofibers  

Microsoft Academic Search

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

Leslie Y. Yeo; James R. Friend

2006-01-01

235

Electron transport in carbon nanotubes encapsulating fullerenes  

Microsoft Academic Search

We study the transport properties of hybrid carbon nanotubes that contain a carbon nanotube capsule and a chain of fullerenes. We find that electron transmissions through the outer tubes are very sensitive to the alignment of inner shells. For a (5,5) capsule in the (10,10) tube, mirror symmetries in cross sections determine the lineshape of antiresonances. For a chain of

D.-H. Kim; H.-S. Sim; K. J. Chang

2001-01-01

236

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

PubMed

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

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

2013-10-15

237

Computational aspects of carbon and boron nanotubes.  

PubMed

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

Manuel, Paul

2010-01-01

238

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

239

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

240

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

PubMed

In this paper, a highly selective sample clean-up procedure combining magnetic dummy molecular imprinting with solid-phase extraction was developed for rapid separation and determination of 4-nonylphenol (NP) in the environmental water samples. The magnetic dummy molecularly imprinted polymers (mag-DMIPs) based on multi-walled carbon nanotubes were successfully synthesized with a surface molecular imprinting technique using 4-tert-octylphenol as the dummy template and tetraethylorthosilicate as the cross-linker. The maximum adsorption capacity of the mag-DMIPs for NP was 52.4mgg(-1) and it took about 20min to achieve the adsorption equilibrium. The mag-DMIPs exhibited the specific selective adsorption toward NP. Coupled with high performance liquid chromatography analysis, the mag-DMIPs were used to extract solid-phase and detect NP in real water samples successfully with the recoveries of 88.6-98.1%. PMID:25059145

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

2014-10-01

241

Electrical response of carbon nanotubes under electrolyte  

NASA Astrophysics Data System (ADS)

Chemical and electrical properties of carbon nanotubes regarding surface chemistry, carrier transport, current fluctuations, and electron-phonon interactions have been explored by utilizing electrolyte top gated carbon nanotube based devices. Individual semiconducting nanotubes have shown a negative threshold voltage shift at low pHs. The potential offsets induced by surface charges on carbon nanotubes have been considered to explain the observed pH response of nanotube transistors under electrolyte. The noise measurements have been carried out in order to examine effects of potential surface chargeable groups as carrier trapping/scattering sites on electron transport properties. The measured current fluctuations have a distinct dependence on the threshold voltage of nanotube devices. This result suggests non-uniform energy distribution of potential carrier trapping/scattering sites, which may include surface groups on carbon nanotubes. In addition, 1/f noise characterizations have been utilized to investigate intrinsic carrier transport properties of metallic carbon nanotubes. Metallic nanotubes exhibit resonance-like enhancements in current fluctuations only when electrons attain enough energy from applied electric field to emit optical phonons and the Fermi level lies near the band crossing point. The Fermi level dependent enhancements in noise amplitude have been correlated with Raman G-band broadening. These observations suggest that F optical phonons have dominant effects on the rise of current fluctuations rather than K zone-boundary phonons that limit current carrying capacity.

Back, Ju Hee

242

Electronic properties of electrochemically modified single-walled carbon nanotubes  

Microsoft Academic Search

The functionalization of carbon nanotubes is a research topic with applications in a wide range of fields, from carbon nanotube based electronic sensor development to improving the electrical properties of carbon nanotubes for use as interconnects between larger circuit elements. This dissertation examines the impact of point-functionalizations on the conductance of single carbon nanotube devices. Due to their reduced size

Vaikunth Rawloo Khalap

2010-01-01

243

Metal and alloy nanowires: Iron and invar inside carbon nanotubes  

NASA Astrophysics Data System (ADS)

Pyrolysis of hydrocarbons over metal catalysts has proved to be a very efficient and versatile technique for generating metal-filled carbon nanotubes. At reduced pressures Fe-filled nanotubes are formed efficiently from ferrocene and C60. Recently, alloys such as invar (Fe65Ni35) were successfully introduced in carbon nanotubes by pyrolysing aerosols of nickelocene/ferrocene (Cp2Ni/Cp2Fe) mixtures dissolved in benzene. With the introduction of Invar in carbon nanotubes it is now possible to study the physico chemical properties of these wires. Furthermore, the alloy formation notably reduces the formation of unwanted by-products such as amorphous carbon, or metal encapsulated particles. The results also confirm that the use of C60 or Ni/Fe also enhances the growth and crystallinty of the products. The products have been characterized by SEM, HRTEM, EELS, XRD and SQUID. The magnetic properties of metal- and alloy-filled nanotubes may be applied to the fabrication of high density magnetic storage devices, magnetic inks, etc. .

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

2001-11-01

244

Mechanics of carbon nanotube scission under sonication.  

PubMed

As-produced carbon nanotubes come in bundles that must be exfoliated for practical applications in nanocomposites. Sonication not only causes the exfoliation of nanotube bundles but also unwanted scission. An understanding of how precisely sonication induces the scission and exfoliation of nanotubes will help maximising the degree of exfoliation while minimising scission. We present a theoretical study of the mechanics of carbon nanotube scission under sonicaton, based on the accepted view that it is caused by strong gradients in the fluid velocity near a transiently collapsing bubble. We calculate the length-dependent scission rate by taking the actual movement of the nanotube during the collapse of a bubble into account, allowing for the prediction of the temporal evolution of the length distribution of the nanotubes. We show that the dependence of the scission rate on the sonication settings and the nanotube properties results in non-universal, experiment-dependent scission kinetics potentially explaining the variety in experimentally observed scission kinetics. The non-universality arises from the dependence of the maximum strain rate of the fluid experienced by a nanotube on its length. The maximum strain rate that a nanotube experiences increases with decreasing distance to the bubble. As short nanotubes are dragged along more easily by the fluid flow they experience a higher maximum strain rate than longer nanotubes. This dependence of the maximum strain rate on nanotube length affects the scaling of tensile strength with terminal length. We find that the terminal length scales with tensile strength to the power of 1/1.16 instead of with an exponent of 1/2 as found when nanotube motion is neglected. Finally, we show that the mechanism we propose responsible for scission can also explain the exfoliation of carbon nanotube bundles. PMID:24985679

Stegen, J

2014-06-28

245

Computer generated holograms for carbon nanotube arrays.  

PubMed

Multiwalled carbon nanotubes are highly diffractive structures in the optical regime. Their metallic character and large scattering cross-section allow their usage as diffractive elements in Fraunhofer holograms. This work elaborates some important features of the far field diffraction patterns produced from periodic arrays of nanotubes. A theoretical approach for the interaction of arrays of nanotubes with light is presented and a computer generated hologram is calculated by means of periodical patterns. Based on the results, fabrication of carbon nanotube arrays (in holographic patterns) was performed. Experimentally measured diffraction patterns were in good agreement with the calculations. PMID:23478844

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

2013-05-21

246

Review of carbon nanotube nanoelectronics and macroelectronics  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

247

Diamond Nanocrystals Growth on Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Aiming at the growth of diamond nanowires on carbon nanotubes we have studied carbon nanotubes for treatment in pure hydrogen in Hot-Filament assisted chemical vapour deposition reactor (HFCVD). Purified multiwalled carbon nanotubes were dispersed onto silicon substrates, and annealed in pure hydrogen in HFCVD reactor. Important parameters were substrate temperature (650 to 870° C), nanotube density, annealing time (1 to 4 hours), hot-filament temperature (HFVCD, 1900 to 2350° C), and gas pressure (30 to 70 Torr). No catalyst was used, and no methane was introduced in the chamber. Annealed samples were studied by Field Emission SEM and EDX analysis. Results show that for a filament temperature of 2000 to 2350° C, carbon nanotubes are rather stable in atomic hydrogen environment. For higher filament temperatures (>2350° C) nanotubes are converted into microcrystalline graphite, and for lower temperatures (1900-1950° C) nanotubes are etched away. In the conditions in which nanotubes are stable, growth of nano-objects were observed on the surface of nanotubes, in particular nanocrystals (3 to 5 nm in diameter). In some cases growth of nanowires (5 to 10 nm in diameter and 100 to 200 nm in length) was also observed.

Mehedi, Hasan-Al; Gheeraert, Etienne

2010-11-01

248

Carbon nanotubes as heat dissipaters in microelectronics  

NASA Astrophysics Data System (ADS)

We review our recent modelling work of carbon nanotubes as potential candidates for heat dissipation in microelectronics cooling. In the first part, we analyze the impact of nanotube defects on their thermal transport properties. In the second part, we investigate the loss of thermal properties of nanotubes in presence of an interface with various substances, including air and water. Comparison with previous works is established whenever is possible.

Pérez Paz, Alejandro; María García-Lastra, Juan; Markussen, Troels; Sommer Thygesen, Kristian; Rubio, Angel

2013-05-01

249

Aharonov-Bohm Conductance Modulation in Ballistic Carbon Nanotubes  

Microsoft Academic Search

We report on magnetoconductance experiments in ballistic multiwalled carbon nanotubes threaded by magnetic fields as large as 55 T. In the high temperature regime (100 K), giant modulations of the conductance, mediated by the Fermi level location, are unveiled. The experimental data are consistently analyzed in terms of the field-dependent density of states of the external shell that modulates the

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

2007-01-01

250

Carbon nanotube arrays on silicon substrates and their possible application  

Microsoft Academic Search

A method to grow regular arrays of oriented carbon nanotubes on silicon substrates is presented. It has been found that porous silicon is an ideal substrate for growing self-oriented carbon nanotubes on large surfaces. The growth mechanism of nanotube arrays has been discussed. The potential applications of carbon nanotube arrays in flat panel display and in synthesizing of other semiconducting

Shoushan Fan; Wenjie Liang; Haiyan Dang; Nathan Franklin; Thomas Tombler; Michael Chapline; Hongjie Dai

2000-01-01

251

Quantum Capacitance Extraction for Carbon Nanotube Interconnects  

PubMed Central

Electrical transport in metallic carbon nanotubes, especially the ones with diameters of the order of a few nanometers can be best described using the Tomanaga Luttinger liquid (TL) model. Recently, the TL model has been used to create a convenient transmission line like phenomenological model for carbon nanotubes. In this paper, we have characterized metallic nanotubes based on that model, quantifying the quantum capacitances of individual metallic single walled carbon nanotubes and crystalline bundles of single walled tubes of different diameters. Our calculations show that the quantum capacitances for both individual tubes and the bundles show a weak dependence on the diameters of their constituent tubes. The nanotube bundles exhibit a significantly large quantum capacitance due to enhancement of density of states at the Fermi level.

2010-01-01

252

Characterization of Carbon Nanotube Reinforced Nickel  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

253

Characterization of ferromagnetic contacts to carbon nanotubes  

NASA Astrophysics Data System (ADS)

We present an investigation of different thin-film evaporated ferromagnetic materials for their suitability as electrodes in individual single-wall and multi-wall carbon nanotube-based spin devices. Various electrode shapes made from permalloy (Ni81Fe19), the diluted ferromagnet PdFe, and PdFe/Fe bilayers are studied for both their micromagnetic properties and their contact formation to carbon nanotubes. Suitable devices are tested in low-temperature electron transport measurements, displaying the typical tunneling magnetoresistance of carbon nanotube pseudo-spin valves.

Preusche, D.; Schmidmeier, S.; Pallecchi, E.; Dietrich, Ch.; Hüttel, A. K.; Zweck, J.; Strunk, Ch.

2009-10-01

254

Electrical properties of carbon nanotube FETs  

Microsoft Academic Search

The electrical properties of carbon nanotube FETs (CNTFETs) have been studied in detail. The conduction type of the CNTFETs was dependent on the work function of the contact metal, which suggests that Fermi level pinning at the metal\\/nanotube interface is not strong. Chemical doping using F4TCNQ was found to be effective in reducing not only the channel resistance but also

T. Mizutani; Y. Ohno; S. Kishimoto

2008-01-01

255

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

256

Highly aligned carbon nanotube forests coated by superconducting NbC.  

PubMed

The formation of carbon nanotube and superconductor composites makes it possible to produce new and/or improved functionalities that the individual material does not possess. Here we show that coating carbon nanotube forests with superconducting niobium carbide (NbC) does not destroy the microstructure of the nanotubes. NbC also shows much improved superconducting properties such as a higher irreversibility and upper critical field. An upper critical field value of ~5?T at 4.2?K is much greater than the 1.7?T reported in the literature for pure bulk NbC. Furthermore, the aligned carbon nanotubes induce anisotropy in the upper critical field, with a higher upper critical field occurring when the magnetic field is parallel to the carbon nanotube growth direction. These results suggest that highly oriented carbon nanotubes embedded in superconducting NbC matrix can function as defects and effectively enhance the superconducting properties of the NbC. PMID:21847102

Zou, G F; Luo, H M; Baily, S; Zhang, Y Y; Haberkorn, N F; Xiong, J; Bauer, E; McCleskey, T M; Burrell, A K; Civale, L; Zhu, Y T; Macmanus-Driscoll, J L; Jia, Q X

2011-01-01

257

Carbon nanotube transistors, sensors, and beyond  

NASA Astrophysics Data System (ADS)

Carbon nanotubes are tiny hollow cylinders, made from a single graphene sheet, that possess many amazing properties. Another reason why nanotubes have generated intense research activities from scientists of various disciplines is they represent a new class of materials for the study of one-dimensional physics. In this thesis we investigate the electrical transport of semiconducting single-walled carbon nanotubes and their potential applications as biological sensors. Electrons have been predicted, by theoretical physicists, to go through nanotubes without much resistance. But this has not been properly quantified experimentally, and the origin of the routinely observed large resistance in nanotubes is not clear. In this thesis we show that in moderate long high quality nanotubes the electrical transport is limited by electron-phonon scattering. Systematic studies are carried out using many devices of different diameters at various temperatures. The resistance and inverse of peak mobility are observed to decrease linearly with temperature, indicating the influence of phonons. The conductance and peak mobility scales with nanotube diameters also, in a linear fashion and quadratic fashion respectively. Based on electron-phonon scattering, a theory model is developed that can not only predict how the resistance changes with gate voltage but also explain the observed temperature and diameter dependence. This work clarifies the nature of electrical transport in nanotubes and sets a performance limit of nanotube devices in diffusive regime. The electrical transport in nanotubes is extremely sensitive to local electrostatic environment due to their small size, large surface to volume ratio and high mobility, making nanotubes ideal key elements in biological sensors. In the second part of this thesis, we integrate nanotubes with supported lipid bilayers, mimic structures of cell membranes, and use this platform as a way to introduce biomolecules into the vicinity of nanotubes for sensing purpose. The quality of supported lipid bilayers near nanotubes is confirmed by probing the diffusion of lipid molecules. Nanotubes do not slow down lipid diffusions, but act as barriers for proteins bound to membrane embedded receptors. The ability of nanotubes to control membrane protein diffusions can be used to study the complex correlation between protein functions and their diffusion properties. Future efforts can be put into modulating the magnitude of nanotube barriers with electrical potentials for deterministic controls. We also demonstrate that the formation of lipid bilayers and the protein bindings on the membranes can be detected by nanotubes as their conductance are changed by those events. The sensitivity of this system can be improved to near single molecule level.

Zhou, Xinjian

258

Synthesis, characterization and microwave absorption property of doped polyaniline nanocomposites containing TiO 2 nanoparticles and carbon nanotubes  

Microsoft Academic Search

As nanomaterial possessing moderate conductivity, magnetic and dielectric property, novel hexanoic acid (HA)-doped polyaniline (PAni) nanocomposites containing TiO2 nanoparticles (dielectric filler) and carbon nanotubes, CNTs (magnetic fillers such as single-walled carbon nanotube, SWNT and multi-walled carbon nanotube, MWNT) were prepared by template free method. The PAni were characterized by UV, FTIR, X-ray diffraction (XRD), thermogravimetric (TGA) and scanning electron microscopy

Sook Wai Phang; Masato Tadokoro; Jiro Watanabe; Noriyuki Kuramoto

2008-01-01

259

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

260

Exohydrogenated single-wall carbon nanotubes  

SciTech Connect

An extensive first-principles study of fully exohydrogenated zigzag (n,0) and armchair (n,n) single-wall carbon nanotubes (C{sub n}H{sub n}), polyhedral molecules including cubane, dodecahedrane, and C{sub 60}H{sub 60} points to crucial differences in the electronic and atomic structures relevant to hydrogen storage and device applications. C{sub n}H{sub n}'s are estimated to be stable up to the radius of a (8,8) nanotube, with binding energies proportional to 1/R. Attaching a single hydrogen to any nanotube is always exothermic. Hydrogenation of zigzag nanotubes is found to be more likely than armchair nanotubes with similar radius. Our findings may have important implications for selective functionalization and finding a way of separating similar radius nanotubes from each other.

Yildirim, T.; Guelseren, O.; Ciraci, S.

2001-08-15

261

Determination of trace amounts of Se(IV) by hydride generation atomic fluorescence spectrometry after solid-phase extraction using magnetic multi-walled carbon nanotubes.  

PubMed

A sensitive and simple method using magnetic multi-walled carbon nanotubes, as an adsorbent, has been successfully developed for extraction and preconcentration trace amounts of Se(IV) with detection by hydride generation atomic fluorescence spectrometry. The prepared nanoparticles were confirmed by Fourier transform infrared spectra, X-ray diffraction spectrometry, vibrating sample magnetometry, and transmission electron microscopy. These magnetic nanocomposites can be easily dispersed in aqueous samples and retrieved by the application of external magnetic field via a piece of permanent magnet. The main factors affecting the signal intensity such as sample pH value, adsorbent amount, eluent concentration and volume, sample volume, and coexisting ions have been investigated and established. The absorbent could be repeatedly used at least 100 times. The enhancement factor of the proposed method for Se(IV) was 100. The method had a linear calibration plot in the range from 0.05 to 10.0 ?g L(-1) with a standard deviation of 2.3% at 0.5 ?g L(-1) (n=11). The limit of detection was as low as 0.013 ?g L(-1). Accuracy of the method was evaluated by the analysis of water samples and certified reference materials. PMID:23708547

Wang, Yang; Xie, Jing; Wu, Yichun; Hu, Xiaoya; Yang, Chun; Xu, Qin

2013-08-15

262

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

263

Carbon nanotube polymer composition and devices  

DOEpatents

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

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

2011-06-14

264

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

265

Carbon Nanotube Quantum Dots as THz Detectors.  

National Technical Information Service (NTIS)

In this project we developed very sensitive broadband THz detectors using carbon nanotube quantum dots coupled to antenna-shaped source and drain electrodes. The sensing mechanism is photon-assisted tunneling and leads to a counterintuitive effect: the TH...

P. Barbara

2012-01-01

266

Nanoparticle Decoration of Carbon Nanotubes by Sputtering.  

National Technical Information Service (NTIS)

Vapor phase growth of gold, nickel and titanium metal nanoparticles on multiwall carbon nanotube (MWCNT) buckypaper by sputtering was investigated. The size and distribution of nanoparticles was dependent on the intrinsic binding energy of the metal eleme...

A. N. Reed B. A. Cola C. Muratore J. E. Bultman S. Ganguli

2013-01-01

267

Dielectrophoresis of carbon nanotubes using microelectrodes: a numerical study  

Microsoft Academic Search

Single-walled carbon nanotubes are candidates for a number of electronics and sensing applications, provided nanotubes with semiconducting and metallic band structure can be separated. Dielectrophoresis has recently been demonstrated as a route towards the separation of metallic nanotubes from semiconducting nanotubes, and is moreover a method for controlled assembly of the nanotubes on microstructures that has the possibility to be

Maria Dimaki; Peter Bøggild

2004-01-01

268

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

NASA Technical Reports Server (NTRS)

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

Yamada, Toshishige

1999-01-01

269

Engineering molecular chains in carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

270

Carbon Nanotube Based Light Sensor  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

271

Exciton photophysics of carbon nanotubes.  

PubMed

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 are special because graphite has two energy bands at the Fermi energy related to time-reversal symmetry and because SWNTs are actually one dimensional. This review discusses both theoretical and experimental points of view, thus aiming to provide a summary of the most important work in the field, as well as to identify open questions. PMID:17201684

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

2007-01-01

272

Functionalized carbon nanotubes: biomedical applications  

PubMed Central

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.

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

2012-01-01

273

Controlled Deposition and Alignment of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

274

Nanopumping molecules via a carbon nanotube  

Microsoft Academic Search

We demonstrate the feasibility of using a carbon nanotube to nanopump molecules. Molecular dynamics simulations show that\\u000a the transport and ejection of a C20 molecule via a single-walled carbon nanotube (SWNT) can be achieved by a sustained mechanical actuation driven by two oscillating\\u000a tips. The optimal condition for nanopumping is found when the tip oscillation frequency and magnitude correlate to

Min Chen; Ji Zang; Dingquan Xiao; C. Zhang; Feng Liu

2009-01-01

275

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

276

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

277

Carbon Nanocomposite Based on Carbon Nanotubes and Ultrananocrystalline Diamond  

Microsoft Academic Search

Carbon-based nanostructured materials exhibit many interesting properties that are dictated by the many different bonding configurations available to carbon. Two typical examples are carbon nanotubes (CNTs) and ultrananocrystalline diamond (UNCD), with the former being sp2 bonded carbon and latter being sp3 bonded carbon. Recent advances in micro and nanofabrication techniques have made possible the development of microscale and perhaps even

Xingcheng Xiao; Jian Wang; Orlando Auciello; John A. Carlisle

2004-01-01

278

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

279

Patterned Carbon Nanotube X-Ray Windows  

NASA Astrophysics Data System (ADS)

By lithographically patterning catalyst particles carbon nanotube forests can be grown with nearly arbitrary geometries. The patterned nanotube forest can then be infiltrated via chemical vapor deposition with a variety of materials to form self-supporting structures with the same shape as the nanotube forest. As an application of this process, x-ray window support frames were made using carbon as the infiltrating material. Window supports made with this process could give a lower background signal, higher collection angles, and lower cost processing than current window frames. Characterization of the infiltration and strength of the structure is presented.

Abbott, Jonathan; Vanfleet, Richard; Davis, Robert

2010-10-01

280

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

281

Carbon nanotubes for biomedical imaging: the recent advances.  

PubMed

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

Gong, Hua; Peng, Rui; Liu, Zhuang

2013-12-01

282

Method for nano-pumping using carbon nanotubes  

DOEpatents

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

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

2009-12-15

283

Genesis of diamond nanotubes from carbon nanotubes  

NASA Astrophysics Data System (ADS)

We synthesized sp3-rich crystalline tubular structures, referred to as diamond nanotubes (DNTs), by hot-filament chemical vapor deposition and characterized them using SEM, TEM, EELS, and Raman spectroscopy. The images and spectra indicate the formation of DNTs with internal diameter of about 7-10 nm and external diameter of about 20-30 nm. During the fabrication process, CNTs form first and give way to the synthesis of DNTs. The DNTs show good field emission properties and enhanced temporal stability as compared to CNTs.

Varshney, D.; Makarov, V. I.; Saxena, P.; Scott, J. F.; Weiner, B. R.; Morell, G.

2011-07-01

284

Method for manufacturing high quality carbon nanotubes  

NASA Technical Reports Server (NTRS)

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

Benavides, Jeanette M. (Inventor)

2006-01-01

285

A carbon nanotube strain sensor for structural health monitoring  

Microsoft Academic Search

A carbon nanotube polymer material was used to form a piezoresistive strain sensor for structural health monitoring applications. The polymer improves the interfacial bonding between the nanotubes. Previous single walled carbon nanotube buckypaper sensors produced distorted strain measurements because the van der Waals attraction force allowed axial slipping of the smooth surfaces of the nanotubes. The polymer sensor uses larger

Inpil Kang; Mark J. Schulz; Jay H. Kim; Vesselin Shanov; Donglu Shi

2006-01-01

286

Amplification of terahertz radiation in carbon nanotubes  

NASA Astrophysics Data System (ADS)

We investigate theoretically the feasibility of amplification of terahertz radiation in aligned achiral carbon nanotubes, a zigzag (12,0) and an armchair (10,10) in comparison with a superlattice using a combination of a constant direct current (dc) and a high-frequency alternate current (ac) electric fields. The electric current density expression is derived using the semiclassical Boltzmann transport equation with a constant relaxation time. The electric field is applied along the nanotube axis. Analysis of the current density versus electric field characteristics reveals a negative differential conductivity behavior at high frequency, as well as photon assisted peaks. The photon assisted peaks are about an order of magnitude higher in the carbon nanotubes compared to the superlattice. These strong phenomena in carbon nanotubes can be used to obtain domainless amplification of terahertz radiation at room temperature.

Abukari, Sulemana S.; Adu, Kofi W.; Mensah, Samuel Y.; Mensah, Natalia G.; Dompreh, Kwadwo A.; Twum, Anthony; Rabiu, Musah

2013-04-01

287

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

288

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

PubMed

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

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

2014-01-30

289

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

290

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

PubMed

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

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

2014-07-01

291

Fabrication of a magnet-assisted alignment device for the amperometric detection of capillary electrophoresis using a carbon nanotube/polypropylene composite electrode.  

PubMed

A magnet-assisted alignment device was designed and fabricated for the amperometric detection of CE. It mainly consisted of a magnet-containing electrode holder, a capillary-based microdisc detection electrode, a detection cell, and a micrometer adjuster. To demonstrate the feasibility and performance of the alignment device, it was used in combination with a carbon nanotube/polypropylene (CNT/PP) composite electrode for the determination of p-phenylenediamine, m-aminophenol, and m-dihydroxybenzene in commercial hair dye by CE. The CNT-based electrode was fabricated by packing a melt mixture of CNTs and PP in a piece of fused silica capillary under heat, offering significantly lower operating potentials, substantially enhanced signal-to-noise characteristics, and high resistance to surface fouling. Because magnetic force was employed to move the detection electrode, the alignment system was significantly simplified. It is characterized by simple design and fabrication, high alignment reproducibility, reduced alignment time, and low cost. Both the alignment device and the CNT/PP composite electrode should find a wide range of applications in microchip CE, flowing injection analysis, and other microfluidic analysis systems. PMID:23161656

Xu, Junchao; Zhang, Luyan; Chen, Gang

2013-07-01

292

Polymerization initated at sidewalls of carbon nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

293

Low contact resistance micro thermal switch with carbon-nanotube-enhanced contactor  

Microsoft Academic Search

We demonstrated considerable reduction of thermal contact resistance (TCR) in microscale using carbon nanotubes (CNTs), and applied this technology to a micro thermal switch for magnetic refrigeration. A micro thermal contactor with a PECVD-grown 10 mum long \\

T. Tsukamoto; M. Esashi; S. Tanaka

2009-01-01

294

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

295

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

296

Carbon Nanotube and Graphene Nanoelectromechanical Systems  

NASA Astrophysics Data System (ADS)

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

Aleman, Benjamin Jose

297

Ferromagnetic spin ordering on carbon nanotubes with topological line defects  

NASA Astrophysics Data System (ADS)

We report first-principles total-energy electronic-structure calculations in the density functional theory performed for carbon nanotubes with a topological line defect consisting of pentagon and octagon rings. We find that the ground state of the nanotubes with the topological line defect is ferromagnetic with small but finite magnetic moment of about 0.04?B/Å . Detailed analyses of energy bands and spin densities unequivocally reveal the nature of the ferromagnetic spin ordering which is associated with the peculiar edge-localized states of graphite flakes.

Okada, Susumu; Nakada, Kyoko; Kuwabara, Kei; Daigoku, Kota; Kawai, Takazumi

2006-09-01

298

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

299

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

PubMed

The potential impact of industrial multiwalled carbon nanotubes (MWNTs) was investigated under normalized laboratory conditions according to the International Standard micronucleus assay ISO 21427-1 for 12 days of half-static exposure to 0.1, 1, 10 and 50 mg/l of MWNTs in water. Three different end points were carried out for 12 days of exposure: mortality, growth inhibition and micronuclei induction in erythrocytes of the circulating blood of larvae. Raman spectroscopy analysis was used to study the presence of carbon nanotubes in the biological samples. Considering the high diversity of carbon nanotubes according to their different characteristics, MWNTs were analyzed in Xenopus larvae, comparatively to double-walled carbon nanotubes used in a previous study in similar conditions. Growth inhibition in larvae exposed to 50 mg/l of MWNTs was evidenced; however, no genetoxicity (micronucleus assay) was noticed, at any concentration. Carbon nanotube localization in the larvae leads to different possible hypothesis of mechanisms explaining toxicity in Xenopus. PMID:20735230

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

2010-08-01

300

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

2011-06-01

301

Release characteristics of selected carbon nanotube polymer composites  

EPA Science Inventory

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

302

Carbon Nanotube Reinforced Polymers for Radiation Shielding Applications  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

303

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

304

Molecular Beam Epitaxy Synthesis of Carbon Nanotubes  

Microsoft Academic Search

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

Frank Tsui

2000-01-01

305

Covalent decoration of multi-walled carbon nanotubes with silica nanoparticles  

Microsoft Academic Search

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

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

2005-01-01

306

Molecular Dynamics Simulation of Magnetic Field Induced Orientation of Nanotube-Polymer Composite  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations are carried out to study the reorientation of single wall carbon nanotubes in a polyethylene matrix under the influence of a 25 T magnetic field. The simulations are based on a variant of velocity Verlet algorithm, which relaxes the Larmor time-step restriction while preserving second-order accuracy. Simulations reveal that the unfolding and reorganization of the polyethylene (PE) chain facilitates the reorientation of the single wall carbon nanotubes closer to the direction of the applied magnetic field. Also, they bring out the difference between the behavior of the carbon nanotubes of zigzag chirality and that of armchair chirality.

Al-Haik, Marwan S.; Hussaini, M. Yousuff

2006-11-01

307

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

308

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

PubMed

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

Daneshvar Tarigh, Ghazale; Shemirani, Farzaneh

2013-10-15

309

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

310

Electrical properties of carbon nanotube FETs  

Microsoft Academic Search

The electrical properties of carbon nanotube FETs (CNTFETs) have been studied in detail. The conduction type of the CNTFETs was dependent on the work function of the contact metal, which suggests that Fermi level pinning at the metal\\/nanotube interface does not happen. Based on the two-probe and four-probe resistance measurements, it was shown that the carrier transport at the contact

T. Mizutani; Y. Nosho; Y. Ohno

2008-01-01

311

Electrical properties of carbon nanotube FETs  

Microsoft Academic Search

The electrical properties of carbon nanotube FETs (CNTFETs) have been studied in detail. The conduction type of the CNTFETs was dependent on the work function of the contact metal, which suggests that Fermi level pinning at the metal\\/nanotube interface is not strong. Based on the two-probe and four-probe resistance measurements, it has been shown that the carrier transport at the

T. Mizutani; Y. Ohno; S. Kishimoto

2008-01-01

312

Modulated Chemical Doping of Individual Carbon Nanotubes  

Microsoft Academic Search

Modulation doping of a semiconducting single-walled carbon nanotube along its length leads to an intramolecular wire electronic device. The nanotube is doped n-type for half of its length and p-type for the other half. Electrostatic gating can tune the system into p-n junctions, causing it to exhibit rectifying characteristics or negative differential conductance. The system can also be tuned into

Chongwu Zhou; Jing Kong; Erhan Yenilmez; Hongjie Dai

2000-01-01

313

A 500 MHz carbon nanotube transistor oscillator  

NASA Astrophysics Data System (ADS)

Operation of a carbon nanotube field effect transistor (FET) oscillator at a record frequency of 500 MHz is described. The FET was fabricated using a large parallel array of single-walled nanotubes grown by chemical vapor deposition on ST-quartz substrates. Matching of the gate capacitance with a series inductor enabled greater than unity net oscillator loop gain to be achieved at 500 MHz.

Pesetski, A. A.; Baumgardner, J. E.; Krishnaswamy, S. V.; Zhang, H.; Adam, J. D.; Kocabas, C.; Banks, T.; Rogers, J. A.

2008-09-01

314

Solid state growth mechanisms for carbon nanotubes  

Microsoft Academic Search

The mechanisms by which carbon nanotubes nucleate and grow remain poorly understood. This paper reviews the models which have been proposed to explain nanotube growth in the arc-evaporation and laser-vaporisation processes. Many of the early models assumed that growth is a gas phase phenomenon but there is growing experimental evidence that the formation of both multiwalled and single-walled tubes involves

Peter J. F. Harris; J. J. Thomson

2007-01-01

315

Nanotubes and Other Forms of Carbon  

NSDL National Science Digital Library

This set of videos, from the University of Wisconsin, show visualizations of the forms of carbon: graphite, graphine, diamond, fullerene, and nanotube. For each of the these forms, a model shows how the carbon atoms fit together to produce the arrangement of each.

2009-05-16

316

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

317

Raman Investigation of Singlewalled Carbon Nanotubes  

Microsoft Academic Search

Singlewalled carbon nanotubes (SWNT's) prepared by the electric arc method are characterized by means of spectroscopic techniques, mainly Transmission Electron Microscopy and resonance Raman scattering. TEM observations reveal the existence of nïckel particles embedded in an amorphous carbon matrix, but also a large concentration of SWNT's, whose average diameter can be estimated to be near 1.3 nm, arranged in bundles.

S. Lefrant; M. Lamy de la Chapelle; I. Baltog; C. Journet; P. Bernier; E. Munoz; A. Benito; W. K. Maser; M. T. Martinez; G. F. de la Fuente; D. Laplaze; A. Loiseau

1998-01-01

318

Formation of Carbon Nanotubes in a Microgravity Environment  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

319

Modeling and simulation of carbon nanotube interconnects  

NASA Astrophysics Data System (ADS)

It has been long predicted that as semiconductor processes scale down in accordance with Moore's Law, integrated circuits will soon hit a performance roadblock due to the several issues of manufacturability and material properties of traditional interconnect wiring. The biggest bottleneck in current generation semiconductors are the problems in IC power dissipation and the huge slowdown seen in the interconnect network. It is possible to work around this problem though the use of nanoscale circuitry which would not only reduce the average distance a signal has to travel on a chip but also allow for an unparalleled scale of systems integration into a single chip. This may be possible though the use of molecular interconnect networks such as carbon nanotubes. In recent times carbon nanotubes have emerged as an exciting new material that holds a lot of promise to shape tomorrow's microelectronics. In our research we have endeavored to evaluate the suitability of carbon nanotubes as a candidate for the interconnect material on a chip. We have calibrated RF models for different carbon nanotube morphologies based on the Tomonaga Luttinger theory. Through a combination of ab initio density functional theory (DFT) calculations and custom developed transport simulation software based on Non Equilibrium Green's Functions, we have been able to reduce arbitrary carbon nanotube microstrip lines to an equivalent R,L,C network. These parameters were then used to simulate signal propagation using a Fourier Space transmission line equation solver.

Parkash, Vidur

320

Electron-ion quantum plasma excitations in single-walled carbon nanotubes.  

PubMed

The effect of a uniform static external magnetic field in the Voigt configuration on electron-ion quantum plasma oscillations in single-walled carbon nanotubes is discussed using the linearized quantum hydrodynamic model in conjunction with Maxwell's equations. Transverse magnetic waves which propagate parallel to the surface of the nanotubes, in the presence of an external magnetic field, yield a spectrum containing a quantum magnetosonic branch in addition to the magnetoplasmon branch. PMID:21715799

Moradi, Afshin

2009-01-28

321

Respiratory toxicity of multi-wall carbon nanotubes  

Microsoft Academic Search

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

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

2005-01-01

322

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

323

Prospective Ways for Production and Application of Longer Carbon Nanotubes  

Microsoft Academic Search

Carbon nanotubes can become a cheaper alternative to carbon fibers based on traditional technology. The conditions for successful longer carbon nanotube catalytic growth are formulated. Optimization is needed in order to break through three general limitations, which prevent nanotubes from reaching great length: slow growth; growth quenching, which is manifested by stopping growth due to catalyst capsulation or poisoning or

V. Z. Mordkovich; A. R. Karaeva

2010-01-01

324

Direct imaging of carbon nanotubes spontaneously filled with solvent.  

PubMed

For the first time, cryo-TEM imaging is used to directly show spontaneous filling of carbon nanotubes immersed in a solvent in the native state at ambient conditions. Multi-walled carbon nanotubes are dissolved in chlorosulfonic acid, and the high contrast between the acid and the carbon shows the difference between filled and unfilled nanotubes. PMID:21103560

Green, Micah J; Young, Colin C; Parra-Vasquez, A Nicholas G; Majumder, Mainak; Juloori, Varun; Behabtu, Natnael; Pint, Cary L; Schmidt, Judith; Kesselman, Ellina; Hauge, Robert H; Cohen, Yachin; Talmon, Yeshayahu; Pasquali, Matteo

2011-01-28

325

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

326

Mechanics of Carbon Nanotubes and their Polymer Composites  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

327

Measurement Challenges for Carbon Nanotube Material  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

328

Interaction of pristine and functionalized carbon nanotubes with lipid membranes.  

PubMed

Carbon nanotubes are widely used in a growing number of applications. Their interactions with biological materials, cell membranes in particular, is of interest in applications including drug delivery and for understanding the toxicity of carbon nanotubes. We use extensive molecular dynamics simulations with the MARTINI model to study the interactions of model nanotubes of different thickness, length, and patterns of chemical modification with model membranes. In addition, we characterize the interactions of small bundles of carbon nanotubes with membrane models. Short pristine carbon nanotubes readily insert into membranes and adopt an orientation parallel to the plane of the membrane in the center of the membrane. Larger aggregates and functionalized nanotubes exhibit a range of possible interactions. The distribution and orientation of carbon nanotubes can be controlled by functionalizing the nanotubes. Free energy calculations provide thermodynamic insight into the preferred orientations of different nanotubes and quantify structural defects in the lipid matrix. PMID:24024494

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

2013-10-10

329

Magnetic nanoparticles and nanotubes for biomedical applications  

NASA Astrophysics Data System (ADS)

Magnetic nanomaterials, especially nanoparticles and nanotubes, are among the most widely used nanomaterials for biomedical applications, and they are also the most promising nanomaterials for clinical treatments. This paper starts with the fundamentals for nanomedicine and magnetic nanomedicine. After discussing the basic requirements for the biomedical applications, the properties and the biomedical applications of magnetic nanoparticles and nanotubes are discussed. Our results indicate that, with suitable functionalization, iron oxide nanomaterials are non-toxic to biological systems, and they are ideal drug carriers which can be remotely controlled by external magnetic fields. At the final part of this paper, the challenges and our approach for targeted drug delivery with controlled release are discussed.

Chen, Linfeng; Xie, Jining; Yancey, Justin; Srivatsan, Malathi; Varadan, Vijay K.

2009-03-01

330

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

PubMed

Cell tracking by magnetic resonance imaging (MRI) is an emerging technique that typically requires the use of MRI contrast agents (CAs). A MRI CA for cellular imaging should label cells efficiently at potentially safe concentrations, have high relaxivity, and not affect the cellular machinery. In this article, we report the cytotoxicity, cytocompatibility, and cell labeling efficiency in NIH/3T3 fibroblasts of novel, single-walled carbon nanotubes synthesized using gadolinium nanoparticles as catalysts (Gd-SWCNTs). Cells incubated with the Gd-SWCNT showed a dose- (50-100 µg/mL nanotube concentration) and time- (12-48 h) dependent decrease in viability. 30% cell death was observed for cells incubated with Gd-SWCNTs at the maximum dose of 100 µg/mL for 48 h. Cells incubated with the Gd-SWCNTs at concentrations between 1-10 ?g/mL for 48 h showed no change in viability or proliferation compared to untreated controls. Additionally, at these potentially safe concentrations, up to 48 h, the cells showed no phosphatidyl serine externalization (pre-apoptotic condition), caspase-3 activity (point of no return for apoptosis), genetic damage, or changes in their division cycle. Localization of Gd-SWCNTs within the cells was confirmed by transmission electron microscopy (TEM) and Raman microscopy, and these results show 100% cell labeling efficiency. Elemental analysis also indicates significant uptake of Gd-SWCNTs by the cells (10(8) -10(9) Gd(3+) ions per cell). Finally, T1 -weighted MRI at 3 T of Gd-SWCNT-labelled cells show up to a four-fold increase in MR signal intensities as compared to untreated cells. These results indicate that Gd-SWCNTs label cells efficiently at potentially safe concentrations, and enhance MRI contrast without any structural damage to the cells. PMID:23686792

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

2013-12-01

331

Growth of Ag nanocrystals on multiwalled carbon nanotubes and Ag-carbon nanotube interaction  

Microsoft Academic Search

The experimental investigations on the interaction between Ag-nanocrystal particles (Ag-NCPs) and carbon nanotubes (CNTs)\\u000a in Ag-nanocrystal particles\\/carbon nanotubes (Ag-NCPs\\/CNTs) hybrid structures were reported. The growth of Ag-NCPs on multiwalled\\u000a carbon nanotubes (MWCNTs) was carried out by thermal evaporation deposition. High-resolution transmission electron microscopy\\u000a and X-ray diffraction analyses revealed that Ag-NCPs had the crystal lattice feature of face-centered cube (fcc). The

ZhenXia Wang; XinNian Li; CuiLan Ren; ZhenZhong Yong; JianKang Zhu; WenYun Luo; XiaoMing Fang

2009-01-01

332

Selective Eradication of Individual Carbon Nanotubes from Vertically Aligned Arrays  

Microsoft Academic Search

Selective eradication is presented as a post- processing technique for as-grown vertically aligned carbon nanotubes (CNTs) for removing unwanted individual nanotubes in order to generate desired patterns. A scanning anode is applied to select a nanotube in a CNT emitter array. Using a saturated emission current, a nanotube emitter can be removed in a controlled way. Vertically aligned single multi-

Arunkumar Subramanian; Lixin Dong; Bradley J. Nelson

2005-01-01

333

Molecular photodesorption from single-walled carbon nanotubes  

Microsoft Academic Search

Probing the photoelectrical properties of single-walled carbon nanotubes (SWNTs) led to the discovery of photoinduced molecular desorption phenomena in nanotube molecular wires. These phenomena were found to be generic to various molecule-nanotube systems. Photodesorption strongly depends on the wavelength of light, the details of which lead to a fundamental understanding of how light stimulates molecular desorption from nanotubes. The results

Robert J. Chen; Nathan R. Franklin; Jing Kong; Jien Cao; Thomas W. Tombler; Yuegang Zhang; Hongjie Dai

2001-01-01

334

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

335

Carbon nanotube-chalcogenide glass composite  

SciTech Connect

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

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

2010-01-15

336

Detection of gas atoms with carbon nanotubes  

NASA Astrophysics Data System (ADS)

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.

2013-05-01

337

Mechanism of Strain Release in Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Despite the potential impact that carbon nanotubes and their composites would have in many areas of science and industry, very little is known about their microscopic strength or their behavior under mechanical load. We have investigated the static and dynamical properties of carbon nanotubes under uniaxial tension, using both massively parallel first-principles methods and classical many body potentials. The simulations have led to an identification of the first stages of the mechanical yield of carbon nanotubes. Beyond a critical value of the tension, the system releases its excess strain via formation of topological defects. In strained nanotubes at high temperatures we observe the spontaneous formation of double pentagon-heptagon defect pairs. Tubes containing these defects are energetically preferred to uniformly stretched tubes at strains greater than 5%. These topological defects act as nucleation centers for the formation of dislocations in the originally ideal graphite network, and they constitute the onset of a plastic deformation of the carbon nanotube. The mechanism of formation of such defects, their energetics and transformations will be described.

Buongiorno Nardelli, M.; Yakobson, B. I.; Bernholc, J.

1998-03-01

338

Building smart materials based on carbon nanotubes  

NASA Astrophysics Data System (ADS)

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

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

2004-07-01

339

Production of carbon nanotubes by AC arc discharge method  

NASA Astrophysics Data System (ADS)

We describe a method for the synthesis of multiwalled carbon nanotubes by AC arc discharge. The discharge is maintained in a magnetic field whose strength can be varied. The soot obtained was purified in several steps. The structure and morphology of the MWCNTs thus produced are characterized by using Transmission Electron Microscopy (TEM) and Raman Spectroscopy. The produced MWCNTs are found to be of high quality as seen from characterization results. However there is wide dispersion in outer diameter and number of walls.

Vishalli; Singh, Charanjit; Dharamvir, Keya; Singhal, Sonal

2013-06-01

340

Propagative Landau states and Fermi level pinning in carbon nanotubes.  

PubMed

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

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

2009-12-18

341

Fe nanowires in carbon nanotubes as an example of a one-dimensional system of exchange-coupled ferromagnetic nanoparticles  

Microsoft Academic Search

The cooperative phenomena revealed in the field and temperature dependences of the magnetization in a system of iron nanoparticles\\u000a in carbon nanotubes were studied experimentally. The character of the temperature dependences of the magnetization indicates\\u000a that the ferromagnetic Fe particles in carbon nanotubes are exchange-coupled. In the region where the magnetization approaches\\u000a saturation, the magnetization curves reveal the power dependence

R. S. Iskhakov; S. V. Komogortsev; A. D. Balaev; A. V. Okotrub; A. G. Kudashov; V. L. Kuznetsov; Yu. V. Butenko

2003-01-01

342

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

343

Mechanically interlocked single-wall carbon nanotubes.  

PubMed

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

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

2014-05-19

344

Organic Photovoltaics Utilizing Doped Carbon Nanotube Electrodes  

NASA Astrophysics Data System (ADS)

Single walled carbon nanotube sheets are an attractive electrode material for organic photovoltaics (OPV) due to their transparency, flexibility, and ease of fabrication and processing. However the conductivity and roughness of these sheets of nanotubes often limits their success. We have developed techniques to P-dope these nanotubes with a strong acceptor such as 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) which can increase the conductivity of the sheet up to four times. This doping can also benefit the transport layers by dramatically increasing their conductivity and enhancing their ohmic contact with the electrodes and intrinsically semiconducting active layers. In this presentation we will show results from several configurations of OPV devices with nanotubes functioning as either bottom or top electrodes.

Cook, Alexander; Mielczarek, Kamil; Pozdin, Vladimir; Kaskela, Antti; Nasibulin, Albert; Kauppinen, Esko; Bhatt, Mahesh; Sista, Prakash; Stefan, Mihaela; Zakhidov, Anvar

2012-02-01

345

Crosstalk analysis of carbon nanotube bundle interconnects  

PubMed Central

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.

2012-01-01

346

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

347

Carbon nanotube-clamped metal atomic chain  

PubMed Central

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

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

2010-01-01

348

Carbon Nanotube-Enhanced Carbon-Phenenolic Ablator Material  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the use of PICA (phenolic impregnated carbon ablator) as the selected material for heat shielding for future earth return vehicles. It briefly reviews the manufacturing of PICA and the advantages for the use of heat shielding, and then explains the reason for using Carbon Nanotubes to improve strength of phenolic resin that binds carbon fibers together. It reviews the work being done to create a carbon nanotube enhanced PICA. Also shown are various micrographic images of the various PICA materials.

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

2006-01-01

349

Individual alumina nanotubes coaxially wrapping carbon nanotubes and nanowires  

Microsoft Academic Search

Al-based anodic porous alumina membranes with ordered nanopore arrays are fabricated for exploring the template synthesis of carbon nanotubes and nanowires. Via the polymerization of acrylonitrile in the ordered nanopores of the membranes and subsequent heating, the polymer structure was converted into a quasi-graphitic structure. Atomic force microscopy observations revealed that the quasi-graphitic nanostructures are located in the pores of

T. Qiu; X. L. Wu; G. S. Huang; G. G. Siu; Y. F. Mei; F. Kong; M. Jiang

2005-01-01

350

Ultralight multiwalled carbon nanotube aerogel.  

PubMed

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

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

2010-12-28

351

Computational Nanomechanics of Carbon Nanotubes and Composites  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

352

Compressed carbon nanotubes: A family of new multifunctional carbon allotropes  

PubMed Central

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

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

2013-01-01

353

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

354

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

PubMed

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

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

2014-02-15

355

Simulation and modeling of carbon nanotube devices  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) are molecular wires that exhibit a number of exceptional chemical, electronic, and mechanical properties. Investigating on these properties and exploring conceptual usages of these properties in devices are conducted by using simulation tools ranging from molecular dynamics, tight-binding, to ab-initio simulations. Four major aspects of carbon nanotube devices are studied. First, we investigate the mechanism of using CNTs to detect the presence of chemical gases such as NO2, NH3, and O2. We discover that the process of NO2 gas sensing is not simply the process of adsorption and desorption of NO2 gas on the CNT surface, but rather it involves the complex process of NO2 gas molecule's reaction on the CNTs surface, which produce NO and NO3 molecules. These findings show that NO3 is the real agent behind the slow recovery of SWCNTs as sensing devices. We also conduct analysis on molecular adsorption on charged SWCNT by electric field manipulation. Secondly, to detect the presence of CO and water molecules that have long evaded the detection of intrinsic carbon nanotubes as sensing devices, we propose the design of a new breed of nanotube based sensor devices. These devices are developed by substitutional doping of the so-called impurity atoms (such as Boron, Nitrogen atoms) into intrinsic single wall carbon nanotubes, or by using composite BxCyNz nanotubes. Thirdly, the effects of flattening and bending on the size of the band gap in CNT are examined. Increasing cross-sectional flattening is found to initially close the band gap in semiconducting tubes, while ultimately re-opening the gap at high degrees of flattening. Using the properties of deformed nanotubes, a simple design for a CNT based quantum well device is proposed. Finally, interactions of metal atoms (Al, Ti) with semiconducting single walled carbon nanotube (SWCNT) are investigated. Comparison of the energetics of these metal atoms on (8,0) CNT surface shows significant differences in binding energy and diffusion barriers. These differences provide us with an explanation of why most of metal atoms (such as Al) form discrete particles on nanotube, while titanium atoms form continuous nanowires.

Peng, Shu

356

Improved Method of Purifying Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

Delzeit, Lance D.

2004-01-01

357

Nanotubes.  

PubMed

Carbon nanotubes were discovered soon after the successful laboratory synthesis of fullerenes. Since their discovery in 1991, there has been intensive research activity in the area of carbon nanotubes, not only because of their fascinating structural features and properties, but also because of their potential technological applications. There is increasing experimental evidence to show that carbon nanotubes may find use in nanoelectronic devices, displays, and in hydrogen storage. In this article, we discuss various important aspects related to the synthesis, structure, characterization, and mechanism of formation of multi-walled and single-walled carbon nanotubes, followed by a presentation of the important electronic, mechanical, hydrogen storage, and other properties of the nanotubes. Doping, as well as other chemical manipulations with boron and nitrogen, bring about significant changes in the properties of the nanotubes. Carbon nanotubes also serve as useful templates to make other nanostructures. Layered metal chalcogenides, boron nitride, and other materials form nanotubes and provide considerable scope for study. PMID:23696434

Rao, C N; Satishkumar, B C; Govindaraj, A; Nath, M

2001-02-16

358

Coupling of carbon and peptide nanotubes.  

PubMed

Two of the main types of nanotubular architectures are the single-walled carbon nanotubes (SWCNTs) and the self-assembling cyclic peptide nanotubes (SCPNs). We here report the preparation of the dual composite resulting from the ordered combination of both tubular motifs. In the resulting architecture, the SWCNTs can act as templates for the assembly of SCPNs that engage the carbon nanotubes noncovalently via pyrene "paddles", each member of the resulting hybrid stabilizing the other in aqueous solution. The particular hybrids obtained in the present study formed highly ordered oriented arrays and display complementary properties such as electrical conductivity. Furthermore, a self-sorting of the cyclic peptides toward semiconducting rather than metallic SWCNTs is also observed in the aqueous dispersions. It is envisaged that a broad range of exploitable properties may be achieved and/or controlled by varying the cyclic peptide components of similar SWCNT/SCPN hybrids. PMID:24471492

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

2014-02-12

359

On the vibrations of single-walled carbon nanotubes  

Microsoft Academic Search

In this paper, a detailed numerical study on the free and forced vibrations of single walled carbon nanotubes is presented. A simple and straightforward method developed such that the proximity of the mathematical model to the actual atomic structure of the nanotube is significantly retained, is used for this purpose. Both zigzag and armchair chiralities of the carbon nanotubes for

S. Arghavan; A. V. Singh

2011-01-01

360

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...

361

Spin-dependent electronic hybridization in a rope of carbon nanotubes  

NASA Astrophysics Data System (ADS)

We demonstrate single-electron addition to different strands of a carbon nanotube rope. Anticrossings of anomalous conductance peaks occur in quantum transport measurements through the parallel quantum dots forming on the individual strands. We determine the magnitude and the sign of the hybridization as well as the Coulomb interaction between the carbon nanotube quantum dots, finding that the bonding states dominate the transport. In a magnetic field the hybridization is shown to be selectively suppressed due to spin effects.

Goß, Karin; Smerat, Sebastian; Leijnse, Martin; Wegewijs, Maarten R.; Schneider, Claus M.; Meyer, Carola

2011-05-01

362

High-damping carbon nanotube hinged micromirrors.  

PubMed

New developments in digital mirror devices (DMDs) require suspension hinges with a good damping and high temperature stability. Carbon nanotubes (CNTs) offer these unique properties. Herein it is shown how CNT hinges can be integrated in micromirrors. The image illustrates a micromirror with a CNT suspension, and a typical overdamped stepresponse (Q-factor < 0.5). PMID:22511407

De Volder, Michaël F L; De Coster, Jeroen; Reynaerts, Dominiek; Van Hoof, Chris; Kim, Sang-Gook

2012-07-01

363

An Electrothermal Carbon Nanotube Gas Sensor  

Microsoft Academic Search

We show both gas pressure and species sensing capabilities based on the electrothermal effect of a multiwalled carbon nanotube (MWCNT). Upon exposure to gaseous environments, the resistance of a heated MWCNT is found to change following the conductive heat-transfer variances of gas molecules. To realize this mechanism, a suspended MWCNT is constructed by synthesis and assembly in localized chemical vapor

Takeshi Kawano; Heather C. Chiamori; Marcel Suter; Qin Zhou; Brian D. Sosnowchik; Liwei Lin

2007-01-01

364

CVD growth of carbon nanotube bundle arrays  

Microsoft Academic Search

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

Michael J. Bronikowski

2006-01-01

365

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

366

Conductance of AFM Deformed Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

367

Electrochemically functionalized carbon nanotubes for device applications  

Microsoft Academic Search

The application range of carbon nanotubes (CNTs) has been significantly expanded by the advent of reliable chemical functionalization methods. This article surveys electrochemistry-based approaches that have been devised for the covalent and non-covalent modification of CNTs, and highlights their increasing importance in the development of nanoscale and macroscopic CNT devices. The primary focus is on electrochemical protocols for selective functionalization

Kannan Balasubramanian; Marko Burghard

2008-01-01

368

Carbon Nanotube Inter and Intramolecular Logic Gates  

Microsoft Academic Search

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

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

2001-01-01

369

Physics and applications of aligned carbon nanotubes  

Microsoft Academic Search

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

Yucheng Lan; Yang Wang; Z. F. Ren

2011-01-01

370

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

371

Multiwall carbon nanotubes reinforced epoxy nanocomposites  

NASA Astrophysics Data System (ADS)

The emergence of carbon nanotubes (CNTs) has led to myriad possibilities for structural polymer composites with superior specific modulus, strength, and toughness. While the research activities in carbon nanotube reinforced polymer composites (NRPs) have made enormous progress towards fabricating next-generation advanced structural materials with added thermal, optical, and electrical advantages, questions concerning the filler dispersion, interface, and CNT alignment in these composites remain partially addressed. In this dissertation, the key technical challenges related to the synthesis, processing, and reinforcing mechanics governing the effective mechanical properties of NRPs were introduced and reviewed in the first two chapters. Subsequently, issues on the dispersion, interface control, hierarchical structure, and multi-functionality of NRPs were addressed based on functionalized multi-walled carbon nanotube reinforced DGEBA epoxy systems (NREs). In chapter 3, NREs with enhanced flexural properties were discussed in the context of improved dispersion and in-situ formation of covalent bonds at the interface. In chapter 4, NREs with controlled interface and tailored thermomechanical properties were demonstrated through the judicious choice of surface functionality and resin chemistry. In chapter 5, processing-condition-induced CNT organization in hierarchical epoxy nanocomposites was analyzed. In Chapter 6, possibilities were explored for multi-functional NREs for underwater acoustic structural applications. Finally, the findings of this dissertation were concluded and future research was proposed for ordered carbon nanotube array reinforced nanocomposites in the last chapter. Four journal publications resulted from this work are listed in Appendix.

Chen, Wei

372

Brittle ductile transition in carbon nanotube bundles  

Microsoft Academic Search

The superior strength and stiffness of carbon nanotubes (CNTs) make them attractive for many structural applications. Although the strength and stiffness of CNTs are extremely high, fibres of aligned CNTs have been found to date to be far weaker than the constituent CNTs. The intermolecular interactions between the CNTs in the fibres are governed by weak van der Waals forces,

Charles F. Cornwell; Charles R. Welch

2012-01-01

373

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

374

Carbon Nanotubes--the Route Toward Applications  

Microsoft Academic Search

Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects. Some of these applications are now realized in products. Others are demonstrated in early to advanced devices, and one, hydrogen storage, is clouded

Ray H. Baughman; Anvar A. Zakhidov; Walt A. de Heer

2002-01-01

375

SYNTHESIS, CHARACTERIZATON, AND APPLICATION OF CARBON NANOTUBES  

Microsoft Academic Search

Carbon nanotubes (CNTs) have attracted increasing attention because of their unique structural, mechanical, and electronic properties. Surface chemistry modifications are also useful and critical to manipulate the adsorptive properties of CNTs and develop their potential of environmental application. Therefore, the main objectives of this study were to investigate the optimal synthesis methods or characteristics identification of multiwall CNTs (MWCNTs) and

Ruey-Bing Li; Frank Lee; Li-Cheng Lou; Su-Wei Chiu

376

Conductance switching in diarylethenes bridging carbon nanotubes  

Microsoft Academic Search

The recently reported photoswitching of diarylethene derivative molecules bridging carbon nanotube (CNT) contacts is theoretically analyzed. The short lifetime of the lowest unoccupiedmolecular orbital (LUMO) indicates that neither the open nor closed form of the molecule can be photoexcited into a charge-neutral excited state for any appreciable length of time preventing photochromic ring opening. Analysis of the highest occupiedmolecular orbital

M. K. Ashraf; Nicolas A. Bruque; Jeremy L. Tan; Gregory J. O. Beran; Roger K. Lake

2011-01-01

377

Conductance switching in diarylethenes bridging carbon nanotubes  

Microsoft Academic Search

The recently reported photoswitching of diarylethene derivative molecules bridging carbon nanotube (CNT) contacts is theoretically analyzed. The short lifetime of the lowest unoccupied molecular orbital (LUMO) indicates that neither the open nor closed form of the molecule can be photoexcited into a charge-neutral excited state for any appreciable length of time preventing photochromic ring opening. Analysis of the highest occupied

M. K. Ashraf; Nicolas A. Bruque; Jeremy L. Tan; Gregory J. O. Beran; Roger K. Lake

2011-01-01

378

Design and characterization of carbon nanotube nanocomposites  

Microsoft Academic Search

Revolutionary design concepts in future aerospace vehicles will depend on extraordinary material properties to permit significant reduction of mass and size of components, while imparting intelligence. Due to their combination of remarkable electrical and mechanical properties, carbon nanotubes (CNT) are expected to enable this paradigm shift in design concepts. However, significant challenges still exist in translating these CNT properties into

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

2003-01-01

379

Multiwall carbon nanotube elastomeric composites: A review  

Microsoft Academic Search

Nanostructured materials gained great importance in the past decade on account of their wide range of potential applications in many areas. A large interest is devoted to carbon nanotubes that exhibit exceptional electrical and mechanical properties and can therefore be used for the development of a new generation of composite materials. Nevertheless, poor dispersion and poor interfacial bonding limit the full

Liliane Bokobza

2007-01-01

380

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

381

Synthesis of Carbon Nanotube (CNT) Composite Membranes  

PubMed Central

Carbon nanotubes are attractive approach for designing of new membranes for advanced molecular separation because of their unique transport properties and ability to mimic biological protein channels. In this work the synthetic approach for fabrication of carbon nanotubes (CNTs) composite membranes is presented. The method is based on growth of multi walled carbon nanotubes (MWCNT) using chemical vapour deposition (CVD) on the template of nanoporous alumina (PA) membranes. The influence of experimental conditions including carbon precursor, temperature, deposition time, and PA template on CNT growth process and quality of fabricated membranes was investigated. The synthesis of CNT/PA composites with controllable nanotube dimensions such as diameters (30–150 nm), and thickness (5–100 ?m), was demonstrated. The chemical composition and morphological characteristics of fabricated CNT/PA composite membranes were investigated by various characterisation techniques including scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDXS), high resolution transmission electron microscopy (HRTEM) and x-ray diffraction (XRD). Transport properties of prepared membranes were explored by diffusion of dye (Rose Bengal) used as model of hydrophilic transport molecule.

Altalhi, Tariq; Ginic-Markovic, Milena; Han, Ninghui; Clarke, Stephen; Losic, Dusan

2011-01-01

382

Improvement of Carbon Nanotubes using Cryogenic Treatment  

Microsoft Academic Search

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

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

2007-01-01

383

Load transfer mechanism in carbon nanotube ropes  

Microsoft Academic Search

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

Dong Qian; Rodney S. Ruoff

2003-01-01

384

Carbon nanotube superconducting quantum interference device  

Microsoft Academic Search

A superconducting quantum interference device (SQUID) with single-walled carbon nanotube (CNT) Josephson junctions is presented. Quantum confinement in each junction induces a discrete quantum dot (QD) energy level structure, which can be controlled with two lateral electrostatic gates. In addition, a backgate electrode can vary the transparency of the QD barriers, thus permitting change in the hybridization of the QD

J.-P. Cleuziou; W. Wernsdorfer; V. Bouchiat; T. Ondarçuhu; M. Monthioux

2006-01-01

385

Crystalline Ropes of Metallic Carbon Nanotubes  

Microsoft Academic Search

Fullerene single-wall nanotubes (SWNTs) were produced in yields of more than 70 percent by condensation of a laser-vaporized carbon-nickel-cobalt mixture at 1200^circC. X-ray diffraction and electron microscopy showed that these SWNTs are nearly uniform in diameter and that they self-organize into \\

Andreas Thess; Roland Lee; Pavel Nikolaev; Hongjie Dai; Pierre Petit; Jerome Robert; Chunhui Xu; Young Hee Lee; Seong Gon Kim; Andrew G. Rinzler; Daniel T. Colbert; Gustavo E. Scuseria; David Tomanek; John E. Fischer; Richard E. Smalley

1996-01-01

386

Chemistry of Carbon Nanotubes for Everyone  

ERIC Educational Resources Information Center

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

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

2012-01-01

387

Dispersion of Carbon Nanotubes in Liquids  

Microsoft Academic Search

Production processes for carbon nanotubes often produce mixtures of solid morphologies that are mechanically entangled or that self?associate into aggregates. Entangled or aggregated nanoparticles often need to be dispersed into fluid suspensions in order to develop materials that have unique mechanical characteristics or transport properties. This paper reviews the effects of milling, ultrasonication, high shear flow, elongational flow, functionalization, and

Jenny Hilding; Eric A. Grulke; Z. George Zhang; Fran Lockwood

2003-01-01

388

Theoretical investigation of electromechanical effects for graphyne carbon nanotubes.  

PubMed

We present a theoretical study of the electronic and mechanical properties of graphyne-based nanotubes (GNTs). These semiconducting nanotubes result from the elongation of one-third of the covalent interconnections of graphite-based nanotubes by the introduction of yne groups. The effect of charge injection on the dimensions of GNTs was investigated using tight-binding calculations. Low amounts of electron injection are predicted to cause qualitatively different responses for armchair and zigzag graphyne nanotubes. Although the behavior is qualitatively similar to the usual carbon nanotubes, the charge-induced strains are predicted to be smaller for the GNTs than for ordinary single walled carbon nanotubes. PMID:15291635

Coluci, V R; Galvão, D S; Baughman, R H

2004-08-15

389

Carbon-nanotube photonics and optoelectronics  

Microsoft Academic Search

Carbon nanotubes (CNTs) are nearly ideal one-dimensional (1D) systems, with diameters of only 1-3 nm and lengths that can be on the scale of centimetres. Depending on the arrangement of the carbon-atom honeycomb structure with respect to their axis, CNTs can be direct bandgap semiconductors, or metals with nearly ballistic conduction. The excited states of semiconducting CNTs can be produced

Phaedon Avouris; Marcus Freitag; Vasili Perebeinos

2008-01-01

390

Multifunctional and recollectable carbon nanotube ponytails for water purification.  

PubMed

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

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

2014-06-25

391

Reversible fluorescence quenching in carbon nanotubes for biomolecular sensing  

Microsoft Academic Search

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

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

2007-01-01

392

Low-frequency phonons in carbon nanotubes: A continuum approach  

Microsoft Academic Search

Low-frequency phonons in carbon nanotubes are studied using a continuum model which allows consideration of an arbitrary wall thickness for the nanotube. Phonon dispersion relations are calculated for two archetypal examples of carbon nanotubes, the (5,5) and (10,10) tubes. The dependence of the radial breathing mode frequency at Gamma on the inverse nanotube diameter is verified within this model; furthermore,

L. Chico; R. Pérez-Álvarez; C. Cabrillo

2006-01-01

393

Functionalized Carbon Nanotubes for Mixed Matrix Membrane  

NASA Astrophysics Data System (ADS)

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

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

394

Carbon nanotubes on a spider silk scaffold.  

PubMed

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

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

2013-01-01

395

Carbon nanotubes on a spider silk scaffold  

PubMed Central

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

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

2013-01-01

396

Molecular ionization from carbon nanotube paper.  

PubMed

Ambient ionization is achieved by spraying from a carbon nanotube (CNT)-impregnated paper surface under the influence of small voltages (?3?V). Organic molecules give simple high-quality mass spectra without fragmentation in the positive or negative ion modes. Conventional field ionization is ruled out, and it appears that field emission of microdroplets occurs. Microscopic examination of the CNT paper confirms that the nanoscale features at the paper surface are responsible for the high electric fields. Raman spectra imply substantial current flows in the nanotubes. The performance of this analytical method was demonstrated for a range of volatile and nonvolatile compounds and a variety of matrices. PMID:24643979

Narayanan, Rahul; Sarkar, Depanjan; Cooks, R Graham; Pradeep, Thalappil

2014-06-01

397

Biomolecules Functionalized Carbon Nanotubes and Their Applications  

NASA Astrophysics Data System (ADS)

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

Cui, Daxiang

398

STM Studies of Single-walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs) are ideal systems for investigating fundamental properties in one-dimensional (1D) electronic systems and have the potential to revolutionize many aspects of nano/molecular electronics. Scanning tunneling microscopy (STM) has been used to characterize the atomic structure and tunneling density of states of individual SWNTs. Detailed spectroscopic measurements show 1D singularities in the SWNT density of states for both metallic and semiconducting nanotubes. These results have been compared to and agree well with theoretical predictions and tight-binding calculations. SWNTs have also been shortened using the STM to explore the role of finite size, which might be exploited for device applications. Nanotube segments less than 10 nm exhibited discrete peaks in the tunneling spectra, which correspond to quantized energy levels, and whose spacing scales inversely with length. Finally, the interaction between magnetic impurities and electrons confined to 1D has been studied by spatially resolving the local electronic density of states of small cobalt clusters on metallic SWNTs. Spectroscopic measurements performed on and near these clusters exhibit a narrow peak near the Fermi level that has been identified as a Kondo resonance. In addition, spectroscopic studies of ultra-small magnetic nanostructures, consisting of small cobalt clusters on short nanotube pieces, exhibited features characteristic of the bulk Kondo resonance, but also new features due to finite size.

Odom, Teri

2001-03-01

399

Fabrication and field emission properties of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Research on the area of the fabrication of carbon nanotubes is fundamental and critical to the entire subject of carbon nanotubes. This dissertation describes an experiment to fabricate carbon nanotubes by the method of Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD) and the electron field emission properties of carbon nanotubes. A MPECVD system was built and used to fabricate the vertical aligned carbon nanotube film. Scanning electron microscope (SEM), Raman spectroscopy and transmission electron microscopy (TEM) were used to characterize the as-grown carbon nanotube samples. By using a metal-containing diblock copolymer catalyst, carbon nanotubes with a diameter of 4 to 7 nm were synthesized. The effect of growth parameters was studied and these parameters were optimized. The growth of high density (˜ 109/cm2) and large coverage area (˜ 1 cm2) carbon nanotube film on glass substrate at low growth temperature was realized. Based on a series of experiments, the effects of oxygen atoms and Ti/N underlayer on the growth were studied. A series of experiments were evaluated to characterize the field emission properties of the various carbon nanotube cathodes. A simple technique of scratching the pattern surface by a cotton swab was found effective to activate more carbon nanotubes to emit. By using the techniques of photolithography and shadow mask, various carbon nanotube patterns were achieved in order to obtain high emission current density and a low threshold electric field. The lowest threshold electric field was found to be 2.3 V/um. The highest current density was found to be 2.2 mA/cm2 when the electric field was 4.7 V/um. Our work shows that it is feasible to provide greater control over the fabrication of carbon nanotubes so that more obstacles in the broad application of carbon nanotubes can be overcome.

Wang, Peng

400

Transmission Through Carbon Nanotubes with Polyhedral Caps  

NASA Technical Reports Server (NTRS)

We study electron transport between capped carbon nanotubes and a substrate, and relate this transport to the local density of states in the cap. Our results show that that the transmission probability mimics the behavior of the density of states at all energies except those that correspond to localized states. For a capped carbon nanotube that is not connected to a substrate, the localized states do not couple to the coexisting continuum states. However, close proximity of a substrate causes hybridization between these states. As a result, new transmission paths open from substrate states to nanotube continuum states via the localized states in the cap. We show that the interference between various paths gives rise to transmission antiresonances with the minimum equal to zero at the energy of the localized state. The presence of defects in the tube places close to the cap transforms antiresonances into resonances. Depending on the spatial position of defects, these resonant states are capable of carrying a large current. The results of this paper are of relevance to carbon nanotube based studies on molecular electronics and probe tip applications.

Anantram, M. P.; Govindan, T. R.

1999-01-01

401

One dimensionality and spectroscopy in carbon nanotubes  

NASA Astrophysics Data System (ADS)

Unlike regular three-dimensional solids two of a nanotube dimensions are confined and quantized. Bulk samples consist of irregular networks of merging and splitting bundles of parallel tubes. On a local scale, nanotubes are at the same time one-dimensional crystals and two-dimensional quantum rings. They have attracted extensive studies on individual aspects in their electronic and optical properties [1]. The current contribution aims at bridging the fundamental physical concepts behind carbon nanotubes to their unique spectroscopic signatures in optical absorption, luminescence, Raman and electron energy loss spectroscopy. The aim is not to compete with the local depth of a focused review, but to briefly convey the physical concept and related spectroscopic signatures of one-dimensionality. Indirect signatures are the manifold appearances of van Hove singularities in their optical transitions. Direct probes of one-dimensionality unveil the confined momentum space, which manifests in the distinction of localized and propagating excitations.

Kramberger, C.

2013-08-01

402

Spin-based optomechanics with carbon nanotubes.  

PubMed

A simple scheme for determination of spin-orbit coupling strength in spinbased optomechanics with carbon nanotubes is introduced, under the control of a strong pump field and a weak signal field. The physical mechanism comes from the phonon induced transparency (PIT), by relying on the coherent coupling of electron spin to vibrational motion of the nanotube, which is analogous to electromagnetically induced transparency (EIT) effect in atom systems. Based on this spin-nanotube optomechanical system, we also conceptually design a single photon router and a quantum microwave transistor, with ultralow pump power (~ pW) and tunable switching time, which should provide a unique platform for the study of spin-based microwave quantum optics and quantum information processing. PMID:23198093

Li, Jin-Jin; Zhu, Ka-Di

2012-01-01

403

Spin-based Optomechanics with Carbon Nanotubes  

PubMed Central

A simple scheme for determination of spin-orbit coupling strength in spinbased optomechanics with carbon nanotubes is introduced, under the control of a strong pump field and a weak signal field. The physical mechanism comes from the phonon induced transparency (PIT), by relying on the coherent coupling of electron spin to vibrational motion of the nanotube, which is analogous to electromagnetically induced transparency (EIT) effect in atom systems. Based on this spin-nanotube optomechanical system, we also conceptually design a single photon router and a quantum microwave transistor, with ultralow pump power (~ pW) and tunable switching time, which should provide a unique platform for the study of spin-based microwave quantum optics and quantum information processing.

Li, Jin-Jin; Zhu, Ka-Di

2012-01-01

404

A novel hybrid of carbon nanotubes\\/iron nanoparticles: iron-filled nodule-containing carbon nanotubes  

Microsoft Academic Search

A straightforward, one-step method for the preparation of novel carbon nanotube\\/iron nanoparticle hybrids with some degree of shape control is reported herein. These carbon nanostructures differ from those reported previously: the nanoparticles were not attached to or coated onto the surface of carbon nanotubes but embedded inside the carbon wall. They were synthesized in good yield by thermolysis of ferrocene

Suwen Liu; Rudolf J. Wehmschulte

2005-01-01

405

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

PubMed

In this manuscript, a new method based on the use of off-line dispersive solid-phase extraction (dSPE) combined with ultra-high performance liquid chromatography with diode-array detection was developed to determine 11 sulfonamide antibiotics (sulfanilamide, sulfacetamide, sulfadiazine, sulfathiazole, sulfamerazine, sulfadimidin, sulfamethoxypyridazine, sulfadoxine, sulfamethoxazole, sulfisoxazole and sulfadimethoxine) in mineral waters with different mineral content. For this purpose, pristine multi-walled carbon nanotubes (MWCNTs) and magnetic-MWCNTs (m-MWCNTs) were used as sorbents. Magnetic nanoparticles were synthesized by means of a solvothermal process, assembled onto CNTs through an "aggregation wrap" mechanism and characterized by scanning electron microscopy. Parameters affecting the extraction such as volume and pH of the sample, amount of sorbent and type and volume of eluent were optimized. Once optimum extraction conditions (250 mL of water at pH 6.0 and elution with 25 mL of MeOH) were obtained, the extraction efficiency of the different carbon nanomaterials was compared. Results demonstrated the higher extraction capacity of pristine MWCNTs with recoveries between 61 and 110% (except for sulfacetamide which ranged between 40 and 53%) and between 22 and 77% for m-MWCNTs. Limits of detection lower than 32 ng/L were achieved for all of the analyzed samples. PMID:24148463

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

2013-11-15

406

From Vapor-Grown Carbon Fibers (Vgcfs) To Carbon Nanotubes  

Microsoft Academic Search

\\u000a Careful growth control during chemical vapor deposition makes it possible to obtain various morphologies of carbon fibers:\\u000a from normal vapor-grown carbon fibers (VGCFs) through submicron VGCFs to nanofibers or carbon nanotubes. The combined effects\\u000a of excellent physical properties and low production costs have spurred applications research for these fibers in various fields.

M. Endo; Y. A. Kim; T. Matusita; T. Hayashi

407

Interaction between fluorene-based polymers and carbon nanotubes\\/carbon nanotube field-effect transistors  

Microsoft Academic Search

We study the interaction between fluorene-based conjugating polymers and various chiralities of single-walled carbon nanotubes (SWNTs). The fluorene-based polymers are able to selectively wrap the SWNTs with certain chiral angles or diameters (1.02~1.06 nm) depending on their chemical structures. This can be used to selectively extract or enrich certain species of nanotubes. For example, high purity of (7, 5) SWNTs

Lain-Jong Li; Fuming Chen; Yumeng Shi; Keke Zhang; Xiaochen Dong

2008-01-01

408

Atomic and electronic structure of divacancies in carbon nanotubes  

NASA Astrophysics Data System (ADS)

We present atomic and electronic structure of divacancies in carbon nanotubes, which is calculated using the density functional theory. Divacancies in carbon nanotubes self-heal by spontaneous reconstructions, which consist of concerted bond formations. Divacancy formation energies EDV , which strongly depend on the divacancy orientation with respect to the tube axis, are in the range of 2.8 4.3 eV for favorable orientations in the nanotubes of 4 9Å diameter, making divacancies more probable than monovacancies in carbon nanotubes. Defect related states lead to a higher density of states around the Fermi level. Semiconducting nanotubes develop midgap levels that may adversely affect the functionality of carbon nanotube based devices. Our spin polarized density functional calculations show that the exchange splitting of defect-related bands in nonsemiconducting defective nanotubes leads to net spin polarizations of ??-???0.5?B per divacancy for some divacancy orientations.

Berber, Savas; Oshiyama, Atsushi

2008-04-01

409

Carbon Nanotubes: Synthesis and Characterization  

Microsoft Academic Search

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

Yamini Yadav; Vindhya Kunduru; Shalini Prasad

410

Automated manipulation of carbon nanotubes using atomic force microscopy.  

PubMed

The manipulation of carbon nanotubes is an important and essential step for carbon-based nanodevice or nanocircuit assembly. However, the conventional push-and-image approach of manipulating carbon nanotubes using atomic force microscopy has low efficiency on account of the reduplicated scanning process during manipulation. In this article, an automated manipulation system is designed and tested. This automated manipulation system, which includes an atomic force microscope platform and a self-developed computer program for one-dimensional manipulation, is capable of automatically moving any assigned individual carbon nanotube to a defined target location without any intermediate scanning procedure. To demonstrate the high-efficiency of this automated manipulation system and its potential applications in nanoassembly, two experiments were conducted. The first experiment used this system to manipulate a carbon nanotube to a defined target location. In the second experiment, this system was used to automatically manipulate several carbon nanotubes for generating and translating a defined pattern of nanotubes. PMID:23646781

Zhang, Chao; Wu, Sen; Fu, Xing

2013-01-01

411

Carbon nanotube based stationary phases for microchip chromatography.  

PubMed

The objective of this article is to provide an overview and critical evaluation of the use of carbon nanotubes and related carbon-based nanomaterials for microchip chromatography. The unique properties of carbon nanotubes, such as a very high surface area and intriguing adsorptive behaviour, have already been demonstrated in more classical formats, for improved separation performance in gas and liquid chromatography, and for unique applications in solid phase extraction. Carbon nanotubes are now also entering the field of microfluidics, where there is a large potential to be able to provide integrated, tailor-made nanotube columns by means of catalytic growth of the nanotubes inside the fluidic channels. An evaluation of the different implementations of carbon nanotubes and related carbon-based nanomaterials for microfluidic chromatography devices is given in terms of separation performance and ease of fabrication. PMID:22566131

Mogensen, Klaus B; Kutter, Jörg P

2012-05-01

412

Carbon nanotube formation by laser direct writing  

SciTech Connect

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

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

2008-07-14

413

Process for derivatizing carbon nanotubes with diazonium species  

NASA Technical Reports Server (NTRS)

The invention incorporates new processes for the chemical modification of carbon nanotubes. Such processes involve the derivatization of multi- and single-wall carbon nanotubes, including small diameter (ca. 0.7 nm) single-wall carbon nanotubes, with diazonium species. The method allows the chemical attachment of a variety of organic compounds to the side and ends of carbon nanotubes. These chemically modified nanotubes have applications in polymer composite materials, molecular electronic applications and sensor devices. The methods of derivatization include electrochemical induced reactions thermally induced reactions (via in-situ generation of diazonium compounds or pre-formed diazonium compounds), and photochemically induced reactions. The derivatization causes significant changes in the spectroscopic properties of the nanotubes. The estimated degree of functionality is ca. 1 out of every 20 to 30 carbons in a nanotube bearing a functionality moiety. Such electrochemical reduction processes can be adapted to apply site-selective chemical functionalization of nanotubes. Moreover, when modified with suitable chemical groups, the derivatized nanotubes are chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as, mechanical strength or electrical conductivity) to the properties of the composite material as a whole. Furthermore, when modified with suitable chemical groups, the groups can be polymerized to form a polymer that includes carbon nanotubes ##STR00001##.

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

2007-01-01

414

Developing Carbon Nanotube Standards at NASA  

NASA Technical Reports Server (NTRS)

Single wall carbon nanotubes (SWCNTs) are currently being produced and processed by several methods. Many researchers are continuously modifying existing methods and developing new methods to incorporate carbon nanotubes into other materials and utilize the phenomenal properties of SWCNTs. These applications require availability of SWCNTs with known properties and there is a need to characterize these materials in a consistent manner. In order to monitor such progress, it is critical to establish a means by which to define the quality of SWCNT material and develop characterization standards to evaluate of nanotube quality across the board. Such characterization standards should be applicable to as-produced materials as well as processed SWCNT materials. In order to address this issue, NASA Johnson Space Center has developed a protocol for purity and dispersion characterization of SWCNTs (Ref.1). The NASA JSC group is currently working with NIST, ANSI and ISO to establish purity and dispersion standards for SWCNT material. A practice guide for nanotube characterization is being developed in cooperation with NIST (Ref.2). Furthermore, work is in progress to incorporate additional characterization methods for electrical, mechanical, thermal, optical and other properties of SWCNTs.

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

2007-01-01

415

Developing Carbon Nanotube Standards at NASA  

NASA Technical Reports Server (NTRS)

Single wall carbon nanotubes (SWCNTs) are currently being produced and processed by several methods. Many researchers are continuously modifying existing methods and developing new methods to incorporate carbon nanotubes into other materials and utilize the phenomenal properties of SWCNTs. These applications require availability of SWCNTs with known properties and there is a need to characterize these materials in a consistent manner. In order to monitor such progress, it is critical to establish a means by which to define the quality of SWCNT material and develop characterization standards to evaluate of nanotube quality across the board. Such characterization standards should be applicable to as-produced materials as well as processed SWCNT materials. In order to address this issue, NASA Johnson Space Center has developed a protocol for purity and dispersion characterization of SWCNTs. The NASA JSC group is currently working with NIST, ANSI and ISO to establish purity and dispersion standards for SWCNT material. A practice guide for nanotube characterization is being developed in cooperation with NIST. Furthermore, work is in progress to incorporate additional characterization methods for electrical, mechanical, thermal, optical and other properties of SWCNTs.

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

2007-01-01

416

Time-Resolved Measurements of Carbon Nanotube and Nanohorn Growth  

Microsoft Academic Search

Mechanisms for carbon nanotube growth have been investigated for both laser vaporization (LV) and chemical vapor deposition (CVD) synthesis techniques through the use of time-resolved, in situ laser-based diagnostics for the measurement of absolute growth rates. Optimization of both the production of loose single-wall carbon nanotubes (SWNTs) by LV and the sustained growth of mm-long, vertically-aligned carbon nanotube arrays (VANTAs)

David Geohegan

2005-01-01

417

High volume fraction carbon nanotube-epoxy composites  

Microsoft Academic Search

A versatile processing technique for fabricating epoxy nanocomposites with a high weight fraction of oxidized multi-walled carbon nanotubes is presented. Thin carbon nanotube based preforms were prepared through an oxidation-filtration protocol and then immersed in a pre-polymerized epoxy\\/curing agent solution in acetone. By adjusting the conditions for the oxidation of carbon nanotubes and the epoxy concentration in the as-prepared solution,

Z. Spitalsky; G. Tsoukleri; D. Tasis; C. Krontiras; S. N. Georga; C. Galiotis

2009-01-01

418

Electrostatic sensing and electrochemistry with single carbon nanotubes  

Microsoft Academic Search

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

I. Heller

2009-01-01

419

Tailoring Piezoresistive Sensitivity of Multilayer Carbon Nanotube Composite Strain Sensors  

Microsoft Academic Search

In recent years, carbon nanotubes have been utilized for a variety of applications, including nanoelectronics and various types of sensors. In particular, researchers have sought to take advantage of the superior electrical properties of carbon nanotubes for fabricating novel strain sensors. This article presents a single-walled carbon nanotube (SWNT)-polyelectrolyte (PE) composite thin film strain sensor fabricated with a layer-by-layer (LbL)

K. J. Loh; J. P. Lynch; B. S. Shim; N. A. Kotov

2008-01-01

420

Tailoring Piezoresistive Sensitivity of Multilayer Carbon Nanotube Composite Strain Sensors  

Microsoft Academic Search

In recent years, carbon nanotubes have been utilized for a variety of applications, including nanoelectronics and various types of sensors. In particular, researchers have sought to take advantage of the superior electrical properties of carbon nanotubes for fabricating novel strain sensors. This article presents a single-walled carbon nanotube (SWNT)-polyelectrolyte (PE) composite thin film strain sensor fabricated with a layer- by-layer

K. J. LOH; J. P. LYNCH; N. A. KOTOV

2008-01-01

421

Radiation Vulcanization of Natural Rubber Latex Loaded with Carbon Nanotubes  

Microsoft Academic Search

The radiation vulcanization of natural rubber latex (NRL) has been carried out with 150 keV electrons beam with the presence of carbon nanotubes. The NRL\\/CNTs were prepared by using solving casting method by dispersing carbon nanotubes in a polymer solution and subsequently evaporating the solvent. The load of the carbon nanotubes in the rubber was varied from 1–7wt%. Upon electron beam

Muataz Ali Atieh; Nazif Nazir; Faridah Yusof; Mohammed Fettouhi; Chantara Thevy Ratnam; Mamdouh Alharthi; Khalid Mohammed

2010-01-01

422

Thermogravimetric Analysis of Single-Wall Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

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

Arepalli, Sivram; Nikolaev, Pavel; Gorelik, Olga

2010-01-01

423

DNA-Templated Carbon Nanotube Field-Effect Transistor  

Microsoft Academic Search

The combination of their electronic properties and dimensions makes carbon nanotubes ideal building blocks for molecular electronics. However, the advancement of carbon nanotube-based electronics requires assembly strategies that allow their precise localization and interconnection. Using a scheme based on recognition between molecular building blocks, we report the realization of a self-assembled carbon nanotube field-effect transistor operating at room temperature. A

Kinneret Keren; Rotem S. Berman; Evgeny Buchstab; Uri Sivan; Erez Braun

2003-01-01

424

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

PubMed

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

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

2012-04-01

425

Metallofullerenes in Composite Carbon Nanotubes as a Nanocomputing Memory Device  

Microsoft Academic Search

Here, we investigate a hybrid carbon nanostructure, which comprises two single-open host nanotubes of the same ra- dius and joined by another single-open nanotube, which is centrally located between the host nanotubes but has a smaller radius. A met- allofullerene is then enclosed inside the structure to represent a bit information and is originally located inside one of the host

Yue Chan; Richard K. F. Lee; James M. Hill

2011-01-01

426

Development of Carbon Nanotube-Based Sensors—A Review  

Microsoft Academic Search

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

Benjamin Mahar; Cosmin Laslau; Ronnie Yip; Yu Sun

2007-01-01

427

Preferential ion and water intake using charged carbon nanotubes  

Microsoft Academic Search

We demonstrate that carbon nanotubes can be used for water and ion separation (and subsequent encapsulation) from a salt solution. Three different electrostatic charge distributions on the nanotubes are considered. These different charge distribution patterns change the nanotube intake effectiveness and induce dissimilar effects on water and ion separation. Molecular dynamics simulations demonstrate that when either spatially or temporally alternating

Soumik Banerjee; Sohail Murad; Ishwar K. Puri

2007-01-01

428

Progress towards monodisperse single-walled carbon nanotubes  

Microsoft Academic Search

The defining characteristic of a nanomaterial is that its properties vary as a function of its size. This size dependence can be clearly observed in single-walled carbon nanotubes, where changes in structure at the atomic scale can modify the electronic and optical properties of these materials in a discontinuous manner (for example, changing metallic nanotubes to semiconducting nanotubes and vice

Mark C. Hersam

2008-01-01

429

Van der Waals interaction between two crossed carbon nanotubes  

Microsoft Academic Search

The analytical expressions for the van der Waals potential energy and force between two crossed carbon nanotubes are presented. The Lennard-Jones potential for two carbon atoms and the method of the smeared out approximation suggested by L.A. Girifalco were used. The exact formula is expressed in terms of rational and elliptical functions. The potential and force for carbon nanotubes were

Alexander I. Zhbanov; Evgeny G. Pogorelov; Yia-Chung Chang

2008-01-01

430

A Carbon Nanotube Cable for a Space Elevator  

ERIC Educational Resources Information Center

In this paper the mechanical properties of carbon nanotubes are discussed in connection with the possibility to use them for the construction of a space elevator. From the fundamental information about the structure of a carbon nanotube and the chemical bond between carbon atoms, Young's modulus and the ultimate tensile strength are…

Bochnícek, Zdenek

2013-01-01

431

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

Microsoft Academic Search

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

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

2005-01-01

432

Fabrication and Characterization of Suspended Carbon Nanotube Devices in Liquid  

SciTech Connect

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

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

2006-10-30

433

First-principles study of graphene - carbon nanotube contacts  

NASA Astrophysics Data System (ADS)

The electron transport properties of carbon nanotube -- graphene junctions are investigated with first-principles total energy and electron transport calculations. By combining the advantageous material properties of graphene and nanotubes one can create all carbon hybrid architectures with properties that are particularly well suited to applications. The p-type Schottky barrier height is calculated in model junctions with (8,0) and (10,0) nanotubes in a top-contact configuration. Results indicate a lower barrier in carbon nanotube -- graphene junctions than in other carbon nanotue -- metal systems.

Cook, Brandon; Varga, Kalman

2012-02-01

434

Intercellular carbon nanotube translocation assessed by flow cytometry imaging.  

PubMed

The fate of carbon nanotubes in the organism is still controversial. Here, we propose a statistical high-throughput imaging method to localize and quantify functionalized multiwalled carbon nanotubes in cells. We give the first experimental evidence of an intercellular translocation of carbon nanotubes. This stress-induced longitudinal transfer of nanomaterials is mediated by cell-released microvesicles known as vectors for intercellular communication. This finding raises new critical issues for nanotoxicology, since carbon nanotubes could be disseminated by circulating extracellular cell-released vesicles and visiting several cells in the course of their passage into the organism. PMID:22928721

Marangon, Iris; Boggetto, Nicole; Ménard-Moyon, Cécilia; Venturelli, Enrica; Béoutis, Marie-Lys; Péchoux, Christine; Luciani, Nathalie; Wilhelm, Claire; Bianco, Alberto; Gazeau, Florence

2012-09-12

435

Divacancies in graphene and carbon nanotubes.  

PubMed

Divacancies are among the most important defects that alter the charge transport properties of single-walled carbon nanotubes (SWNT), and we here study, using ab initio calculations, their properties. Two structures were investigated, one that has two pentagons side by side with an octagon (585) and another composed of three pentagons and three heptagons (555777). We investigate their stability as a function of tube diameter, and calculate their charge transport properties. The 585 defect is less stable in graphene due to two broken bonds in the pentagons. We estimate that the 555777 becomes more stable than the 585 for a diameter of about 40 A (53 A) for an armchair (zigzag) SWNTs, indicating that they will prevail in large diameter multiwalled carbon nanotubes and graphene ribbons. PMID:17630813

Amorim, Rodrigo G; Fazzio, A; Antonelli, Alex; Novaes, Frederico D; da Silva, Antônio J R

2007-0