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Sample records for dispersed multiwalled carbon

  1. Multiwalled Carbon Nanotube Dispersion Methods Affect Their Aggregation, Deposition, and Biomarker Response

    EPA Science Inventory

    To systematically evaluate how dispersion methods affect the environmental behaviors of multiwalled carbon nanotubes (MWNTs), MWNTs were dispersed in various solutions (e.g., surfactants, natural organic matter (NOM), and etc.) via ultrasonication (SON) and long-term stirring (LT...

  2. Electrostatic stabilization of multi-walled carbon nanotubes dispersed in nonaqueous media.

    PubMed

    Damasceno, João Paulo V; Zarbin, Aldo J G

    2018-06-04

    Dispersing carbon nanotubes is an easy and low-cost way to manipulate these solids and allows the preparation of more complex materials or devices, so it is fundamental for further uses that these dispersions have controlled properties and high colloidal stability. In this work we report the spontaneous electrical charge build-up in pristine multi-walled carbon nanotubes dispersed in common organic solvents such as chloroform and tetrahydrofuran and the achievement of dispersions stable for long periods without adding passivant agents or functional groups on nanotubes surface. Results from electrokinetics, homo- and heterocoagulation provided macroscopic evidences that carbon nanotubes acquire electric charges after dispersion in some organic liquids and we confirmed this process by measuring in situ Raman spectra of the nanotubes dispersions with higher surface electric potentials. We also show that the signal of electric potential of the dispersions can be predicted by the acid-base behaviour of the dispersing medium, corroborating previously reports for other dispersions of carbon nanomaterials. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. Novel star-like surfactant as dispersant for multi-walled carbon nanotubes in aqueous suspensions at high concentration

    NASA Astrophysics Data System (ADS)

    Qiao, Min; Ran, Qianping; Wu, Shishan

    2018-03-01

    A kind of novel surfactant with star-like molecular structure and terminated sulfonate was synthesized, and it was used as the dispersant for multi-walled carbon nanotubes (CNTs) in aqueous suspensions compared with a traditional single-chained surfactant. The star-like surfactant showed good dispersing ability for multi-walled CNTs in aqueous suspensions. Surface tension analysis, total organic carbon analysis, X-ray photoelectron spectroscopy, zeta potential, dynamic light scattering and transmission electron microscopy were performed to research the effect of star-like surfactant on the dispersion of multi-walled CNTs in aqueous suspensions. With the assistance of star-like surfactant, the CNTs could disperse well in aqueous suspension at high concentration of 50 g/L for more than 30 days, while the CNTs precipitated completely in aqueous suspension after 1 day without any dispersant or after 10 days with sodium 4-dodecylbenzenesulfonic acid as dispersant.

  4. Effect of Acid Oxidation on the Dispersion Property of Multiwalled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Goh, P. S.; Ismail, A. F.; Aziz, M.

    2009-06-01

    A means of dispersion of multiwalled carbon nanotube (MWCNT) via mixed acid (HNO3 and H2SO4) oxidation with different treatment durations was investigated through the solubility study of the treated carbon nanotubes in some common solvents. Fourier transformed infrared (FTIR) characterization of the reaction products revealed that the surface of MWCNTs was successfully functionalized with surface acidic groups. The acid-base titration demonstrated that the amount of surface acidic groups increased in parallel with the refluxing duration. The acid modified MWCNTs were found to be well dispersed in polar solvents, such as ethanol and water due to the presence of the hydrophilic acid functional groups on the surface of raw MWCNTs. Such chemical modification of carbon nanotube properties will pave the way towards the realistic applications in the nanotechnology world.

  5. Dispersion of bamboo type multi-wall carbon nanotubes in calf-thymus double stranded DNA.

    PubMed

    Primo, Emiliano N; Cañete-Rosales, Paulina; Bollo, Soledad; Rubianes, María D; Rivas, Gustavo A

    2013-08-01

    We report for the first time the use of double stranded calf-thymus DNA (dsDNA) to successfully disperse bamboo-like multi-walled carbon nanotubes (bCNT). The dispersion and the modified electrodes were studied by different spectroscopic, microscopic and electrochemical techniques. The drastic treatment for dispersing the bCNT (45min sonication in a 50% (v/v) ethanol:water solution), produces a partial denaturation and a decrease in the length of dsDNA that facilitates the dispersion of CNT and makes possible an efficient electron transfer of guanine residues to the electrode. A critical analysis of the influence of different experimental conditions on the efficiency of the dispersion and on the performance of glassy carbon electrodes (GCE) modified with bCNT-dsDNA dispersion is also reported. The electron transfer of redox probes and guanine residues was more efficient at GCE modified with bCNT dispersed in dsDNA than at GCE modified with hollow CNT (hCNT) dispersed in dsDNA, demonstrating the importance of the presence of bCNT. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Control of multiwall carbon nanotubes dispersion in polyamide6 matrix: An assessment through electrical conductivity

    NASA Astrophysics Data System (ADS)

    Kodgire, Pravin V.; Bhattacharyya, Arup R.; Bose, Suryasarathi; Gupta, Nitin; Kulkarni, Ajit R.; Misra, Ashok

    2006-12-01

    The homogeneous dispersion of carbon nanotubes (CNT) remains a hindrance in exploiting the exceptional properties associated with CNT in polymer/CNT composites. Here we present for the first time the key role of sodium salt of 6-aminohexanoic acid (Na-AHA) in assisting debundling the multiwall carbon nanotubes (MWNT) through specific interactions leading to homogeneous dispersion within polyamide6 (PA6) matrix during melt-mixing. The composite fabricated via this route exhibits low electrical percolation threshold of 0.5 wt% at room temperature, the lowest reported value in this system so far. FTIR and Raman spectroscopy reveal the existence of 'cation-π' interaction between Na-AHA and MWNT. The phenomenon of reactive coupling between amine functionality of Na-AHA and acid end group of PA6 during melt-mixing is also established.

  7. Effect of dispersants of multi-walled carbon nanotubes on cellular uptake and biological responses

    PubMed Central

    Haniu, Hisao; Saito, Naoto; Matsuda, Yoshikazu; Kim, Yoong-Ahm; Park, Ki Chul; Tsukahara, Tamotsu; Usui, Yuki; Aoki, Kaoru; Shimizu, Masayuki; Ogihara, Nobuhide; Hara, Kazuo; Takanashi, Seiji; Okamoto, Masanori; Ishigaki, Norio; Nakamura, Koichi; Kato, Hiroyuki

    2011-01-01

    Although there have been many reports about the cytotoxicity of multi-walled carbon nanotubes (MWCNTs), the results are still controversial. To investigate one possible reason, the authors investigated the influence of MWCNT dispersants on cellular uptake and cytotoxicity. Cytotoxicity was examined (measured by alamarBlue® assay), as well as intracellular MWCNT concentration and cytokine secretion (measured by flow cytometry) in human bronchial epithelial cells (BEAS-2B) exposed to a type of highly purified MWCNT vapor grown carbon fiber (VGCF®, Shōwa Denkō Kabushiki-gaisha, Tokyo, Japan) in three different dispersants (gelatin, carboxylmethyl cellulose, and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine). The authors also researched the relationship between the intracellular concentration of MWCNTs and cytotoxicity by using two cell lines, BEAS-2B and MESO-1 human malignant pleural mesothelioma cells. The intracellular concentration of VGCF was different for each of the three dispersants, and the levels of cytotoxicity and inflammatory response were correlated with the intracellular concentration of VGCF. A relationship between the intracellular concentration of VGCF and cytotoxic effects was observed in both cell lines. The results indicate that dispersants affect VGCF uptake into cells and that cytotoxicity depends on the intracellular concentration of VGCF, not on the exposed dosage. Thus, toxicity appears to depend on exposure time, even at low VGCF concentrations, because VGCF is biopersistent. PMID:22228997

  8. Melt dispersion and electrospinning of non-functionalized multiwalled carbon nanotubes in thermoplastic polyurethane.

    PubMed

    Hunley, Matthew T; Pötschke, Petra; Long, Timothy E

    2009-12-16

    Nanoscale fibers with embedded, aligned, and percolated non-functionalized multiwalled carbon nanotubes (MWCNTs) were fabricated through electrospinning dispersions based on melt-compounded thermoplastic polyurethane/MWCNT nanocomposite, with up to 10 wt.-% MWCNTs. Transmission electron microscopy indicated that the nanotubes were highly oriented and percolated throughout the fibers, even at high MWCNT concentrations. The coupling of efficient melt compounding with electrospinning eliminated the need for intensive surface functionalization or sonication of the MWCNTs, and the high aspect ratio as well as the electrical and mechanical properties of the nanotubes were retained. This method provides a more efficient technique to generate one-dimensional nanofibers with aligned MWCNTs. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Ecotoxicity of multiwalled carbon nanotubes: standardization of the dispersion methods and concentration measurements.

    PubMed

    Cerrillo, Cristina; Barandika, Gotzone; Igartua, Amaya; Areitioaurtena, Olatz; Marcaide, Arrate; Mendoza, Gemma

    2015-08-01

    There are currently a variety of applications for multiwalled carbon nanotubes (MWCNTs), but considerable concerns exist regarding their release into the environment. Their potential accumulation by aquatic organisms could lead to transfer throughout food chains. Considering the divergences in experimental data published on the ecotoxicity of carbon nanotubes, further research is required. The dispersion of MWCNTs in aqueous culturing media of organisms as well as the determination of concentrations are relevant aspects to obtain accurate ecotoxicity results. Ultraviolet-visible spectroscopy is one of the most reported techniques to analyze concentration quickly and economically, but the methodologies to prepare dispersions and selecting the wavelengths for ultraviolet-visible measurements have not yet been clearly defined. The present study demonstrates that dispersion procedures influence absorbance, and an approach to determine the most appropriate measurement wavelength is proposed. Ecotoxicity tests with MWCNTs were performed on Vibrio fischeri bacteria, and divergences in the results were observed with respect to those previously reported. The present study contributes to the attempt to overcome the lack of standardization in the environmental assessment of MWCNTs. © 2015 SETAC.

  10. Enhanced dispersion of multiwall carbon nanotubes in natural rubber latex nanocomposites by surfactants bearing phenyl groups.

    PubMed

    Mohamed, Azmi; Anas, Argo Khoirul; Bakar, Suriani Abu; Ardyani, Tretya; Zin, Wan Manshol W; Ibrahim, Sofian; Sagisaka, Masanobu; Brown, Paul; Eastoe, Julian

    2015-10-01

    Here is presented a systematic study of the dispersibility of multiwall carbon nanotubes (MWCNTs) in natural rubber latex (NR-latex) assisted by a series of single-, double-, and triple-sulfosuccinate anionic surfactants containing phenyl ring moieties. Optical polarising microscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy have been performed to obtain the dispersion-level profiles of the MWCNTs in the nanocomposites. Interestingly, a triple-chain, phenyl-containing surfactant, namely sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3-phenylpropoxy)carbonyl) pentane-2-sulfonate (TCPh), has a greater capacity the stabilisation of MWCNTs than a commercially available single-chain sodium dodecylbenzenesulfonate (SDBS) surfactant. TCPh provides significant enhancements in the electrical conductivity of nanocomposites, up to ∼10(-2) S cm(-1), as measured by a four-point probe instrument. These results have allowed compilation of a road map for the design of surfactant architectures capable of providing the homogeneous dispersion of MWCNTs required for the next generation of polymer-carbon-nanotube materials, specifically those used in aerospace technology. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Dispersion and characterization of Thermoplastic Polyurethane/Multiwalled Carbon Nanotubes in co-rotative twin screw extruder

    NASA Astrophysics Data System (ADS)

    Benedito, Adolfo; Buezas, Ignacio; Giménez, Enrique; Galindo, Begoña

    2010-06-01

    The dispersion of multi-walled carbon nanotubes in thermoplastic polyurethanes has been done in co-rotative twin screw extruder through a melt blending process. A specific experimental design was prepared taking into account different compounding parameters such as feeding, temperature profile, screw speed, screw design, and carbon nanotube loading. The obtained samples were characterized by thermogravimetric analysis (TGA), light transmission microscopy, dynamic rheometry, and dynamic mechanical analysis. The objective of this work has been to study the dispersion quality of the carbon nanotubes and the effect of different compounding parameters to optimize them for industrial scale-up to final applications.

  12. Multi-walled carbon nanotubes: A cytotoxicity study in relation to functionalization, dose and dispersion.

    PubMed

    Zhou, Lulu; Forman, Henry Jay; Ge, Yi; Lunec, Joseph

    2017-08-01

    Chemical functionalization broadens carbon nanotube (CNT) applications, conferring new functions, but at the same time potentially altering toxicity. Although considerable experimental data related to CNT toxicity, at the molecular and cellular levels, have been reported, there is very limited information available for the corresponding mechanism involved (e.g. cell apoptosis and genotoxicity). The threshold dose for safe medical application in relation to both pristine and functionalized carbon nanotubes remains ambiguous. In this study, we evaluated the in vitro cytotoxicity of pristine and functionalized (OH, COOH) multi-walled carbon nanotubes (MWCNTs) for cell viability, oxidant detection, apoptosis and DNA mutations, to determine the non-toxic dose and influence of functional group in a human lung-cancer cell line exposed to 1-1000μg/ml MWCNTs for 24, 48 and 72h. The findings suggest that pristine MWCNTs induced more cell death than functionalized MWCNTs while functionalized MWCNTs are more genotoxic compared to their pristine form. The level of both dose and dispersion in the matrix used should be taken into consideration before applying further clinical applications of MWCNTs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Graphene wrapped multiwalled carbon nanotubes dispersed nanofluids for heat transfer applications

    NASA Astrophysics Data System (ADS)

    Jyothirmayee Aravind, S. S.; Ramaprabhu, S.

    2012-12-01

    A two step method is employed for the preparation of graphene wrapped multiwalled carbon nanotubes (MWNT) dispersed nanofluids. Graphene wrapped MWNT composite is prepared by simple chemical vapor deposition technique and further purified prior to the synthesis of nanofluids. The functionalization of MWNT with the poly electrolyte, graphene drives out the need for surfactants or long term harsh chemical treatments as in the case of pristine carbon materials based nanofluids. The enhancement in thermal transport properties of surfactant free graphene wrapped MWNT composite in de-ionized (DI) water and ethylene glycol (EG) base fluids than that of pristine carbon nanomaterial based nanofluids indicates the potential usage of the hybrid composite based nanofluids in heat transfer applications. An enhancement in thermal conductivity of 11.3% and 13.7% has been attained with 0.04% volume fraction of hybrid composite based DI water and EG nanofluids at 25 °C. The nanocomposite possesses extreme stability in a variety of aqueous solvents without any surfactant. Electrical conductivity of the nanofluids analyzed as a function of volume fraction of nanoparticles and temperature shows a positive effect. Further, the analysis of forced convective heat transfer coefficients of the nanofluids flowing through a stain less steel tube shows significant enhancement in heat transfer, attributed to good aspect ratio of graphene wrapped MWNT and synergistic effect of high thermally conducting graphene and MWNT.

  14. Heat transport in electrically aligned multiwalled carbon nanotubes dispersed in water

    NASA Astrophysics Data System (ADS)

    Cervantes-Alvarez, F.; Macias, J. D.; Alvarado-Gil, J. J.

    2018-02-01

    A modified Ångström method was used to determine the thermal diffusivity and thermal conductivity of aqueous dispersions of multiwalled carbon nanotubes as a function of their weight fraction concentration and in the presence of an externally applied electric field. Measurements were performed in planar samples, with a fixed thickness of 3.18 mm applying an AC voltage in the range from 0 to 70~V_RMS and for concentrations of carbon nanotubes from 0 to 2 wf%. It is shown that this field induces the formation of clusters followed by their alignment along the electric field, which can favor heat transfer in that direction. Heat transfer measurements show two regimes, in the first one under 0.5 wf%, voltages lower than 30~V_RMS are not strong enough to induce the adequate order of the carbon nanostructures, and as a consequence, thermal diffusivity of the dispersion remains close to the thermal diffusivity of water. In contrast for higher concentrations (above 1.5 wf%), 10~V_RMS are enough to get a good alignment. Above such thresholds of concentrations and voltages, thermal diffusivity and conductivity increase, when the electric field is increased, in such a way that for an applied voltage of 20~V_RMS and for a concentration of 1.5 wf%, an increase of 49% of the thermal conductivity was obtained. It is also shown that this approach exhibits limits, due to the fact that the electric-field induced structure, can act as a heating element at high electric field intensities and carbon nanotubes concentrations, which can induce convection and evaporation of the liquid matrix.

  15. Industrial-Graded Epoxy Nanocomposites with Mechanically Dispersed Multi-Walled Carbon Nanotubes: Static and Damping Properties.

    PubMed

    Giovannelli, Andrea; Di Maio, Dario; Scarpa, Fabrizio

    2017-10-24

    The majority of currently published dispersion protocols of carbon nanotubes rely on techniques that are not scalable to an industrial level. This work shows how to obtain polymer nanocomposites with good mechanical characteristics using multi-walled carbon nanotubes epoxy resins obtained by mechanical mixing only. The mechanical dispersion method illustrated in this work is easily scalable to industrial level. The high shearing force due to the complex field of motion produces a good and reproducible carbon nanotube dispersion. We have tested an industrial epoxy matrix with good baseline mechanical characteristics at different carbon nanotube weight loads. ASTM-derived tensile and compressive tests show an increment in both Young's modulus and compressive strength compared with the pristine resin from a starting low wt %. Comparative vibration tests show improvement in the damping capacity. The new carbon nanotube enhanced epoxy resin has superior mechanical proprieties compared to the market average competitor, and is among the top products in the bi-components epoxy resins market. The new dispersion method shows significant potential for the industrial use of CNTs in epoxy matrices.

  16. Industrial-Graded Epoxy Nanocomposites with Mechanically Dispersed Multi-Walled Carbon Nanotubes: Static and Damping Properties

    PubMed Central

    Di Maio, Dario

    2017-01-01

    The majority of currently published dispersion protocols of carbon nanotubes rely on techniques that are not scalable to an industrial level. This work shows how to obtain polymer nanocomposites with good mechanical characteristics using multi-walled carbon nanotubes epoxy resins obtained by mechanical mixing only. The mechanical dispersion method illustrated in this work is easily scalable to industrial level. The high shearing force due to the complex field of motion produces a good and reproducible carbon nanotube dispersion. We have tested an industrial epoxy matrix with good baseline mechanical characteristics at different carbon nanotube weight loads. ASTM-derived tensile and compressive tests show an increment in both Young’s modulus and compressive strength compared with the pristine resin from a starting low wt %. Comparative vibration tests show improvement in the damping capacity. The new carbon nanotube enhanced epoxy resin has superior mechanical proprieties compared to the market average competitor, and is among the top products in the bi-components epoxy resins market. The new dispersion method shows significant potential for the industrial use of CNTs in epoxy matrices. PMID:29064400

  17. Tuning the dispersion of multiwall carbon nanotubes in co-continuous polymer blends: a generic approach

    NASA Astrophysics Data System (ADS)

    Bose, Suryasarathi; Bhattacharyya, Arup R.; Khare, Rupesh A.; Kulkarni, Ajit R.; Umasankar Patro, T.; Sivaraman, P.

    2008-08-01

    Melt-mixed blends of polyamide 6 and acrylonitrile-butadiene-styrene (PA6/ABS) with multiwall carbon nanotubes (MWNTs) were prepared with the intention to develop conducting composites. A generic strategy, namely specific interactions combined with reactive coupling, was adopted to facilitate and to retain the 'network-like' structure of MWNTs during melt-mixing. This was facilitated by the sodium salt of 6-amino hexanoic acid (Na-AHA) and certain phosphonium based modifiers, where it was envisaged that these modifiers would establish specific interactions (either 'cation-π' or 'π-π' ) with the 'π-electron' clouds of MWNTs, as well as restricting them in the PA6 phase of the blends via reactive coupling. This route eventually led to a remarkable increase in the electrical conductivity and dielectric constant in the blends with MWNTs. Raman, FTIR and TEM investigations further supported these observations.

  18. Bioelectrochemical sensing of promethazine with bamboo-type multiwalled carbon nanotubes dispersed in calf-thymus double stranded DNA.

    PubMed

    Primo, Emiliano N; Oviedo, M Belén; Sánchez, Cristián G; Rubianes, María D; Rivas, Gustavo A

    2014-10-01

    We report the quantification of promethazine (PMZ) using glassy carbon electrodes (GCE) modified with bamboo-like multi-walled carbon nanotubes (bCNT) dispersed in double stranded calf-thymus DNA (dsDNA) (GCE/bCNT-dsDNA). Cyclic voltammetry measurements demonstrated that PMZ presents a thin film-confined redox behavior at GCE/bCNT-dsDNA, opposite to the irreversibly-adsorbed behavior obtained at GCE modified with bCNT dispersed in ethanol (GCE/bCNT). Differential pulse voltammetry-adsorptive stripping with medium exchange experiments performed with GCE/bCNT-dsDNA and GCE modified with bCNTs dispersed in single-stranded calf-thymus DNA (ssDNA) confirmed that the interaction between PMZ and bCNT-dsDNA is mainly hydrophobic. These differences are due to the intercalation of PMZ within the dsDNA that supports the bCNTs, as evidenced from the bathochromic displacement of UV-Vis absorption spectra of PMZ and quantum dynamics calculations at DFTB level. The efficient accumulation of PMZ at GCE/bCNT-dsDNA made possible its sensitive quantification at nanomolar levels (sensitivity: (3.50±0.05)×10(8) μA·cm(-2)·M(-1) and detection limit: 23 nM). The biosensor was successfully used for the determination of PMZ in a pharmaceutical product with excellent correlation. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Angular dependent anisotropic terahertz response of vertically aligned multi-walled carbon nanotube arrays with spatial dispersion.

    PubMed

    Zhou, Yixuan; E, Yiwen; Xu, Xinlong; Li, Weilong; Wang, Huan; Zhu, Lipeng; Bai, Jintao; Ren, Zhaoyu; Wang, Li

    2016-12-14

    Spatial dispersion effect of aligned carbon nanotubes (CNTs) in the terahertz (THz) region has significance for both theoretical and applied consideration due to the unique intrinsically anisotropic physical properties of CNTs. Herein, we report the angular dependent reflection of p-polarized THz wave from vertically aligned multi-walled CNT arrays in both experiment and theory. The spectra indicate that the reflection depends on the film thickness of vertically aligned CNTs, the incident angle, and the frequency. The calculation model is based on the spatial dispersion effect of aligned CNTs and performed with effective impedance method and the Maxwell-Garnett approximation. The results fit well with the experiment when the thickness of CNT film is thin, which reveals a coherent superposition mechanism of the CNT surface reflection and CNTs/Si interface reflection. For thick CNT films, the CNTs/Si interface response determines the reflection at small incident angles, while the CNTs surface effect dominates at large incident angles. This work investigates the spatial dispersion effect of vertically aligned CNT arrays in the THz region, and paves a way for potential anisotropic THz applications based on CNTs with oblique incidence requirements.

  20. Angular dependent anisotropic terahertz response of vertically aligned multi-walled carbon nanotube arrays with spatial dispersion

    NASA Astrophysics Data System (ADS)

    Zhou, Yixuan; Yiwen, E.; Xu, Xinlong; Li, Weilong; Wang, Huan; Zhu, Lipeng; Bai, Jintao; Ren, Zhaoyu; Wang, Li

    2016-12-01

    Spatial dispersion effect of aligned carbon nanotubes (CNTs) in the terahertz (THz) region has significance for both theoretical and applied consideration due to the unique intrinsically anisotropic physical properties of CNTs. Herein, we report the angular dependent reflection of p-polarized THz wave from vertically aligned multi-walled CNT arrays in both experiment and theory. The spectra indicate that the reflection depends on the film thickness of vertically aligned CNTs, the incident angle, and the frequency. The calculation model is based on the spatial dispersion effect of aligned CNTs and performed with effective impedance method and the Maxwell-Garnett approximation. The results fit well with the experiment when the thickness of CNT film is thin, which reveals a coherent superposition mechanism of the CNT surface reflection and CNTs/Si interface reflection. For thick CNT films, the CNTs/Si interface response determines the reflection at small incident angles, while the CNTs surface effect dominates at large incident angles. This work investigates the spatial dispersion effect of vertically aligned CNT arrays in the THz region, and paves a way for potential anisotropic THz applications based on CNTs with oblique incidence requirements.

  1. Continuous dry dispersion of multi-walled carbon nanotubes to aerosols with high concentrations of individual fibers

    NASA Astrophysics Data System (ADS)

    Simonow, Barbara Katrin; Wenzlaff, Daniela; Meyer-Plath, Asmus; Dziurowitz, Nico; Thim, Carmen; Thiel, Jana; Jandy, Mikolaj; Plitzko, Sabine

    2018-06-01

    The assessment of the toxicity of airborne nanofibers is an important task. It relies on toxicological inhalation studies and validated exposure measurement techniques. Both require nanofiber-containing aerosols of known morphological composition and controlled fraction of individual fibers. Here, a dry powder dispersion method is presented that operates with mixtures of nanofibers and microscale beads. Aerosolization experiments of mixtures of multi-walled carbon nanotubes (MWCNTs) and glass beads that were continuously fed into a Venturi nozzle enabled high generation rates of aerosols composed of individual and agglomerate nanofiber structures. The aerosol process achieved good stability over more than 2 h with respect to concentration and aerodynamic size distribution. Its operation duration is limited only by the reservoir volume of the cyclone used to separate the beads from the aerosol. The aerosol concentration can be controlled by changing the mass ratio of MWCNTs and glass beads or by adapting the mass feed rate to the nozzle. For two agglomerated MWCNT materials, aerosol concentrations ranged from 1700 to 64,000 nano-objects per cm3. Comprehensive scanning electron microscope analysis of filter samples was performed to categorize and determine the morphological composition of the aerosol, its fiber content as well as fiber length and diameter distributions. High fractions of individual fibers of up to 34% were obtained, which shows the setup to be capable of dispersing also highly tangled MWCNT agglomerates effectively.

  2. Multiwalled carbon nanotubes and dispersed nanodiamond novel hybrids: Microscopic structure evolution, physical properties, and radiation resilience

    SciTech Connect

    Gupta, S.; Farmer, J.

    2011-01-01

    We report the structure and physical properties of novel hybrids of multiwalled carbon nanotubes (MWCNTs) and ultradispersed diamond (UDD) forming nanocomposite ensemble that were subjected to 50, 100, and 10{sup 3} kGy gamma ray doses and characterized using various analytical tools to investigate hierarchical defects evolution. This work is prompted by recent work on single-walled CNTs and UDD ensemble [Gupta et al., J. Appl. Phys. 107, 104308 (2010)] where radiation-induced microscopic defects seem to be stabilized by UDD. The present experiments show similar effects where these hybrids display only a minimal structural modification under the maximum dose. Quantitative analyses ofmore » multiwavelength Raman spectra revealed lattice defects induced by irradiation assessed through the variation in prominent D, G, and 2D bands. A minimal change in the position of D, G, and 2D bands and a marginal increase in intensity of the defect-induced double resonant Raman scattered D and 2D bands are some of the implications suggesting the radiation coupling. The in-plane correlation length (L{sub a}) was also determined following Tunistra-Koenig relation from the ratio of D to G band (I{sub D}/I{sub G}) besides microscopic stress. However, we also suggest the following taking into account of intrinsic defects of the constituents: (a) charge transfer arising at the interface due to the difference in electronegativity of MWCNT C sp{sup 2} and UDD core (C sp{sup 3}) leading to phonon and electron energy renormalization; (b) misorientation of C sp{sup 2} at the interface of MWCNT and UDD shell (C sp{sup 2}) resulting in structural disorder; (c) softening or violation of the q{approx}0 selection rule leading to D band broadening and a minimal change in G band intensity; and (d) normalized intensity of D and G bands with 2D band help to distinguish defect-induced double resonance phenomena. The MWCNT when combined with nanodiamond showed a slight decrease in their conductance

  3. A Comparative Study of the Dispersion of Multi-Wall Carbon Nanotubes Made by Arc-Discharge and Chemical Vapour Deposition.

    PubMed

    Frømyr, Tomas-Roll; Bourgeaux-Goget, Marie; Hansen, Finn Knut

    2015-05-01

    A method has been developed to characterize the dispersion of multi-wall carbon nanotubes in water using a disc centrifuge for the detection of individual carbon nanotubes, residual aggregates, and contaminants. Carbon nanotubes produced by arc-discharge have been measured and compared with carbon nanotubes produced by chemical vapour deposition. Studies performed on both pristine (see text) arc-discharge nanotubes is rather strong and that high ultra-sound intensity is required to achieve complete dispersion of carbon nanotube bundles. The logarithm of the mode of the particle size distribution of the arc-discharge carbon nanotubes was found to be a linear function of the logarithm of the total ultrasonic energy input in the dispersion process.

  4. PEGylation of magnetic multi-walled carbon nanotubes for enhanced selectivity of dispersive solid phase extraction.

    PubMed

    Zeng, Qiong; Liu, Yi-Ming; Jia, Yan-Wei; Wan, Li-Hong; Liao, Xun

    2017-02-01

    Carbon nanotubes (CNTs) possess large potential as extraction absorbents in solid phase extraction. They have been widely applied in biomedicine research, while very rare application in natural product chemistry has been reported. In this work, methoxypolyethylene glycol amine (mPEG-NH 2 ) is covalently coupled to CNTs-magnetic nanoparticles (CNTs-MNP) to prepare a novel magnetic nanocomposite (PEG-CNTs-MNP) for use as dispersive solid-phase extraction (DSPE) absorbent. The average particle size was 86nm, and the saturation magnetization was 52.30emu/g. This nanocomposite exhibits excellent dispersibility in aqueous systems, high selectivity and fast binding kinetics when used for extraction of Z-ligustilide, the characteristic bioactive compound from two popular Asian herbal plants, R. chuanxiong and R. ligusticum. HPLC quantification of Z-ligustilide extracted from the standard sample solution showed a high recovery of 98.9%, and the extraction rate from the extracts of the above two herbs are both around 70.0%. To our knowledge, this is the first report on using PEG-CNTs-MNP as DSPE nanosorbents for selective extraction of natural products. This nano-material has promising application in isolation and enrichment of targeted components from complex matrices. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Automatic dispersion, long-term stability of multi-walled carbon nanotubes in high concentration electrolytes

    NASA Astrophysics Data System (ADS)

    Ma, Lan; He, Yi; Luo, Pingya; Zhang, Liyun; Yu, Yalu

    2018-02-01

    Nanoparticles have been known as the useful materials in working fluids for petroleum industry. But the stabilization of nano-scaled materials in water-based working fluids at high salinities is still a big challenge. In this study, we successfully prepared the anionic polymer/multi-walled carbon nanotubes (MWNTs) composites by covalently wrapping of MWNTs with poly (sodium 4-styrenesulfonate) (PSS) to improve the stability of MWNTs in high concentration electrolytes. The PSS/MWNTs composites can automatically disperse in salinity up to 15 wt% NaCl and API brines (8 wt% NaCl + 2 wt% CaCl2). Hydrodynamic diameters of composites were measured as a function of ionic strength and API brines by dynamic light scattering (DLS). By varying the concentration of brines, hydrodynamic diameter of PSS/MWNTs composites in brines fluctuated between 545 ± 110 nm for 14 days and 673 ± 171 nm for 30 days. Above results showed that PSS/MWNTs could be well stable in high salts solutions for a long period of time. After wrapped with PSS, the diameters of nanotubes changed from 30 40 to 430 nm, the thickness of wrapped polymer is about 400 nm by analysis of morphologies. The zeta potentials of PSS/MWNTs composites in various salinity of brines kept at approximately - 41 - 52 mV. Therefore, the well dispersion of PSS/MWNTs in high salinity is due to large negative charges of poly (sodium 4-styrenesulfonate), which provide enough electrostatic repulsion and steric repulsion to hinder compression of electric double layer caused by high concentration electrolytes.

  6. Amperometric glucose biosensor based on glucose oxidase dispersed in multiwalled carbon nanotubes/graphene oxide hybrid biocomposite.

    PubMed

    Palanisamy, Selvakumar; Cheemalapati, Srikanth; Chen, Shen-Ming

    2014-01-01

    An amperometric glucose biosensor based on enhanced and fast direct electron transfer (DET) of glucose oxidase (GOx) at enzyme dispersed multiwalled carbon nanotubes/graphene oxide (MWCNT/GO) hybrid biocomposite was developed. The fabricated hybrid biocomposite was characterized by transmission electron microscopy (TEM), Raman and infrared spectroscopy (IR). The TEM image of hybrid biocomposite reveals that a thin layer of GOx was covered on the surface of MWCNT/GO hybrid composite. IR results validate that the hybrid biocomposite was formed through the electrostatic interactions between GOx and MWCNT/GO hybrid composite. Further, MWCNT/GO hybrid composite has also been characterized by TEM and UV-visible spectroscopy. A pair of well-defined redox peak was observed for GOx immobilized at the hybrid biocomposite electrode than that immobilized at the MWCNT modified electrode. The electron transfer rate constant (Ks) of GOx at the hybrid biocomposite was calculated to be 11.22s(-1). The higher Ks value revealed that fast DET of GOx occurred at the electrode surface. Moreover, fabricated biosensor showed a good sensitivity towards glucose oxidation over a linear range 0.05-23.2mM. The limit of detection (LOD) was estimated to be 28μM. The good features of the proposed biosensor could be used for the accurate detection of glucose in the biological samples. © 2013.

  7. Dispersion quality of amine functionalized multiwall carbon nanotubes plays critical roles in polymerase chain reaction enhancement

    NASA Astrophysics Data System (ADS)

    Yuce, Meral; Budak, Hikmet

    2014-12-01

    Impact of dispersion quality of NH2-MWCNTs (13-18 nm in diameter with a length between 1 and 12 µm, >99 % purity) in the amplification efficiency of a random DNA oligonucleotide library (96 bp) was investigated. Amplification yield in the presence of non-filtered NH2-MWCNT dispersion, filtered NH2-MWCNT dispersion and surface-attached NH2-MWCNTs was explored, and physical interactions between NH2-MWCNTs and major PCR reagents including DNA template, wild type Taq DNA polymerase enzyme and primers were determined using high resolution polyacrylamide gel electrophoresis, dynamic light scattering, UV-Vis-NIR spectroscopy and scanning electron microscopy techniques. The results revealed that presence of NH2-MWCNT dispersion which was sonicated, centrifuged and filtered, enhanced the total PCR efficiency up to 70 % while the presence of NH2-MWCNT only centrifuged after sonication, inhibited the reaction significantly at similar concentrations. Furthermore, the NH2-MWCNTs coupled covalently onto magnetic microspheres, contributed for the specificity enhancement whilst decreasing the amplification efficiency by 30 % at the maximum concentration, which suggests a removable enhancement system for sensitive applications. On the other hand, the relative hydrodynamic size distribution measurements displayed a clear difference between the filtered NH2 and non-filtered NH2-MWCNT water dispersions, which justifies the inhibition of the amplification by the non-filtered NH2-MWCNTs containing big agglomerates and bundles. Finally, we demonstrated that major PCR components adsorb onto the NH2-MWCNTs with diverse affinities, and maintain their functions after adsorption, which provides a good framework to further develop tunable NH2-MWCNT-carriers to be utilized in various nanobiotechnology and material science applications.

  8. Dispersion of Multi-Walled Carbon Nanotubes in Skutterudites and Its Effect on Thermoelectric and Mechanical Properties.

    PubMed

    Schmitz, Andreas; Schmid, Carolin; de Boor, Johannes; Müller, Eckhard

    2017-03-01

    Filled cobalt-antimony based skutterudites have proven themselves as very promising thermoelectric materials for generator applications in an intermediate temperature range between 400 and 800 K due to their high figure of merit. Besides the functional thermoelectric properties also the skutterudites’ mechanical properties play an important role to withstand external mechanical and internal thermomechanical loads during operation. Properties of interest are hardness as well as fracture toughness and resistance to fatigue. Carbon nano tubes are well known for their high tensile strength and may therefore be used to increase the mechanical strength of composite materials. Additionally, the thermoelectric properties of the composite material might benefit from the high electrical conductivity of carbon nano tubes and increased phonon scattering at interfaces between matrix and carbon nano tube. A main precondition for benefiting from embedded nano-tubes is to achieve a homogeneous distribution of the CNTs and good adhesion between carbon nano tube and matrix material. In this work we present the influence of the introduction of multi-walled carbon nano tubes on the thermoelectric and mechanical properties of p-type skutterudites Ce(0.14)La(0.06)Co(2)Fe(2)Sb(12). The influence of different carbon nano tube concentrations and preparation routes on the resulting composite material’s thermoelectric, mechanical and microstructural properties is studied. A reduction of electrical and thermal conductivity as well as fracture strength is observed with increasing carbon nano tube content which is attributed to strong agglomeration of the nano tubes. The results underline the pivotal role of a homogeneous distribution of the carbon nano tubes for improving the mechanical properties of skutterudites.

  9. Electrophoretic deposition of multi-walled carbon nanotubes on porous anodic aluminum oxide using ionic liquid as a dispersing agent

    NASA Astrophysics Data System (ADS)

    Hekmat, F.; Sohrabi, B.; Rahmanifar, M. S.; Jalali, A.

    2015-06-01

    Multi-wall carbon nanotubes (MW-CNTs) have been arranged in nanochannels of anodic aluminum oxide template (AAO) by electrophoretic deposition (EPD) to make a vertically-aligned carbon nanotube (VA-CNT) based electrode. Well ordered AAO templates were prepared by a two-step anodizing process by applying a constant voltage of 45 V in oxalic acid solution. The stabilized CNTs in a water-soluble room temperature ionic liquid (1-methyl-3-octadecylimidazolium bromide), were deposited in the pores of AAO templates which were conductive by deposition of Ni nanoparticles in the bottom of pores. In order to obtain ideal results, different EPD parameters, such as concentration of MWCNTs and ionic liquid on stability of MWCNT suspensions, deposition time and voltage which are applied in EPD process and also optimal conditions for anodizing of template were investigated. The capacitive performance of prepared electrodes was analyzed by measuring the specific capacitance from cyclic voltammograms and the charge-discharge curves. A maximum value of 50 Fg-1 at the scan rate of 20 mV s-1was achieved for the specific capacitance.

  10. Electrochemical Detection of p-Aminophenol by Flexible Devices Based on Multi-Wall Carbon Nanotubes Dispersed in Electrochemically Modified Nafion

    PubMed Central

    Scandurra, Graziella; Antonella, Arena; Ciofi, Carmine; Saitta, Gaetano; Lanza, Maurizio

    2014-01-01

    A conducting composite prepared by dispersing multi-walled carbon nanotubes (MWCNTs) into a host matrix consisting of Nafion, electrochemically doped with copper, has been prepared, characterized and used to modify one of the gold electrodes of simply designed electrochemical cells having copier grade transparency sheets as substrates. Electrical measurements performed in deionized water show that the Au/Nafion/Au-MWCNTs–Nafion:Cu cells can be successfully used in order to detect the presence of p-aminophenol (PAP) in water, without the need for any supporting electrolyte. The intensity of the redox peaks arising when PAP is added to deionized water is found to be linearly related to the analyte in the range from 0.2 to 1.6 μM, with a detection limit of 90 nM and a sensitivity of 7 μA·(μM−1)·cm−2. PMID:24854357

  11. Dispersion of multi-walled carbon nanotubes in [BMIM]PF6 for electrochemical sensing of acetaminophen.

    PubMed

    Gomes, Rayane N; Sousa, Camila P; Casciano, Paulo N S; Ribeiro, Francisco Wirley P; Morais, Simone; de Lima-Neto, Pedro; Correia, Adriana N

    2018-07-01

    The influence of functionalized multi-walled carbon nanotubes (fMWCNT) in the presence of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF 6 ) in different ratios was investigated on the acetaminophen (ACOP) electrochemical determination. The electrochemical behavior of the ACOP exhibited a pair of well-defined redox peaks, suggesting that the reversibility of ACOP was significantly improved in comparison to irreversible oxidation peak on bare GCE. The redox process was controlled by adsorption, involves two electrons and the value of apparent rate constant (k s ) was equal to 14.7 s -1  ± 3.6 s -1 . The analytical curves were obtained for concentrations of ACOP ranging from 0.3 to 3.0 μmol L -1 . The values of the detection limit were calculated from SWV and found to be 6.73 × 10 -8  mol L -1 . The proposed electrochemical sensor exhibited good stability and reproducibility and was applied for ACOP determination in tablets (Tylenol® and Tylenol®DC) with satisfactory results. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Platinum-TM (TM = Fe, Co) alloy nanoparticles dispersed nitrogen doped (reduced graphene oxide-multiwalled carbon nanotube) hybrid structure cathode electrocatalysts for high performance PEMFC applications.

    PubMed

    Vinayan, B P; Ramaprabhu, S

    2013-06-07

    The efforts to push proton exchange membrane fuel cells (PEMFC) for commercial applications are being undertaken globally. In PEMFC, the sluggish kinetics of oxygen reduction reactions (ORR) at the cathode can be improved by the alloying of platinum with 3d-transition metals (TM = Fe, Co, etc.) and with nitrogen doping, and in the present work we have combined both of these aspects. We describe a facile method for the synthesis of a nitrogen doped (reduced graphene oxide (rGO)-multiwalled carbon nanotubes (MWNTs)) hybrid structure (N-(G-MWNTs)) by the uniform coating of a nitrogen containing polymer over the surface of the hybrid structure (positively surface charged rGO-negatively surface charged MWNTs) followed by the pyrolysis of these (rGO-MWNTs) hybrid structure-polymer composites. The N-(G-MWNTs) hybrid structure is used as a catalyst support for the dispersion of platinum (Pt), platinum-iron (Pt3Fe) and platinum-cobalt (Pt3Co) alloy nanoparticles. The PEMFC performances of Pt-TM alloy nanoparticle dispersed N-(G-MWNTs) hybrid structure electrocatalysts are 5.0 times higher than that of commercial Pt-C electrocatalysts along with very good stability under acidic environment conditions. This work demonstrates a considerable improvement in performance compared to existing cathode electrocatalysts being used in PEMFC and can be extended to the synthesis of metal, metal oxides or metal alloy nanoparticle decorated nitrogen doped carbon nanostructures for various electrochemical energy applications.

  13. Atomic layer deposited highly dispersed platinum nanoparticles supported on non-functionalized multiwalled carbon nanotubes for the hydrogenation of xylose to xylitol

    NASA Astrophysics Data System (ADS)

    Liang, Xinhua; Jiang, Chengjun

    2013-09-01

    Highly dispersed platinum nanoparticles were deposited on gram quantities of non-functionalized multiwalled carbon nanotubes (MWCNTs) by atomic layer deposition (ALD) in a fluidized bed reactor at 300 °C. (Methylcyclopentadienyl) trimethylplatinum and oxygen were used as precursors. The results of TEM analysis showed that 1.3 nm Pt nanoparticles were highly dispersed on non-functionalized MWCNTs. The porous structures of MWCNTs did not change with the deposition of Pt nanoparticles. For comparison, the commercial 3 wt% Pt/C catalyst was also characterized. The ALD-prepared Pt/MWCNT was used for the hydrogenation of xylose to xylitol. The ALD-prepared Pt/MWCNT showed the best catalytic performance with 100 % conversion of xylose and 99.3 % selectivity to xylitol, compared to commercially available Pt/C, Ru/C, and Raney Ni catalysts. The stability of ALD produced Pt/MWCNT catalyst was higher than that of the commercial Pt/C, due to the presence of surface defects on the MWCNTs and the strong metal-support interaction for the ALD-prepared Pt/MWCNT catalyst.

  14. Characterization of multiwalled carbon nanotube-polymethyl methacrylate composite resins as denture base materials.

    PubMed

    Wang, Russell; Tao, Junliang; Yu, Bill; Dai, Liming

    2014-04-01

    Most fractures of dentures occur during function, primarily because of the flexural fatigue of denture resins. The purpose of this study was to evaluate a polymethyl methacrylate denture base material modified with multiwalled carbon nanotubes in terms of fatigue resistance, flexural strength, and resilience. Denture resin specimens were fabricated: control, 0.5 wt%, 1 wt%, and 2 wt% of multiwalled carbon nanotubes. Multiwalled carbon nanotubes were dispersed by sonication. Thermogravimetric analysis was used to determine quantitative dispersions of multiwalled carbon nanotubes in polymethyl methacrylate. Raman spectroscopic analyses were used to evaluate interfacial reactions between the multiwalled carbon nanotubes and the polymethyl methacrylate matrix. Groups with and without multiwalled carbon nanotubes were subjected to a 3-point-bending test for flexural strength. Resilience was derived from a stress and/or strain curve. Fatigue resistance was conducted by a 4-point bending test. Fractured surfaces were analyzed by scanning electron microscopy. One-way ANOVA and the Duncan tests were used to identify any statistical differences (α=.05). Thermogravimetric analysis verified the accurate amounts of multiwalled carbon nanotubes dispersed in the polymethyl methacrylate resin. Raman spectroscopy showed an interfacial reaction between the multiwalled carbon nanotubes and the polymethyl methacrylate matrix. Statistical analyses revealed significant differences in static and dynamic loadings among the groups. The worst mechanical properties were in the 2 wt% multiwalled carbon nanotubes (P<.05), and 0.5 wt% and 1 wt% multiwalled carbon nanotubes significantly improved flexural strength and resilience. All multiwalled carbon nanotubes-polymethyl methacrylate groups showed poor fatigue resistance. The scanning electron microscopy results indicated more agglomerations in the 2% multiwalled carbon nanotubes. Multiwalled carbon nanotubes-polymethyl methacrylate groups

  15. Passive approach for the improved dispersion of polyvinyl alcohol-based functionalized multi-walled carbon nanotubes/Nafion membranes for polymer electrolyte membrane fuel cells.

    PubMed

    Abu Sayeed, M D; Talukdar, Krishan; Kim, Hee Jin; Park, Younjin; Gopalan, A I; Kim, Young Ho; Lee, Kwang-Pill; Choi, Sang-June

    2014-12-01

    Multi-walled carbon nanotubes (MWCNTs) are regarded as ideal fillers for Nafion polymer electrolyte membranes (PEMs) for fuel cell applications. The highly aggregated properties of MWCNTs can be overcome by the successful cross-linking with polyvinyl alcohol (PVA) into the MWCNTs/Nafion membrane. In this study, a series of nanocomposite membranes were fabricated with the PVA-influenced functionalized MWCNTs reinforced into the Nafion polymer matrix by a solution casting method. Several different PVA contents were blended to f-MWCNTs/Nafion nanocomposite membranes followed by successful cross-linking by annealing. The surface morphologies and the inner structures of the resulting PVA-MWCNTs/Nafion nanocomposite membranes were then observed by optical microscopy and scanning electron microscopy (SEM) to investigate the dispersion of MWCNTs into the PVA/Nafion composite membranes. After that, the nanocomposite membranes were characterized by thermo-gravimetric analysis (TGA) to observe the thermal enhancement caused by effective cross-linking between the f-MWCNTs with the composite polymer matrixes. Improved water uptake with reduced methanol uptake revealed the successful fabrication of PVA-blended f-MWCNTs/Nafion membranes. In addition, the ion exchange capacity (IEC) was evaluated for PEM fuel cell (PEMFC) applications.

  16. Multi-walled carbon nanotubes-dispersive solid-phase extraction combined with liquid chromatography-tandem mass spectrometry for the analysis of 18 sulfonamides in pork.

    PubMed

    Hou, Xiao-Lin; Wu, Yin-Liang; Yang, Ting; Du, Xiang-Dang

    2013-06-15

    A simple and cost-effective pre-treatment procedure was developed for 18 sulfonamides in pork using dispersive solid phase extraction (dSPE) with multi-walled carbon nanotubes (MWCNTs). The sample was analysed after purification by ultra high-performance liquid chromatography-positive electrospray ionisation tandem mass spectrometry (UHPLC-ESI-MS/MS). After extraction with phosphate buffer (pH 6.0), a dSPE procedure was conducted with MWCNTs. The pH value of the extract, extraction time with MWCNTs, type and amount of MWCNTs and type of eluent were optimised to increase the sample throughput and sensitivity. The samples were quantified using sulfamethazine-(13)C6 as an internal standard. The recoveries of the target compounds from the pork samples were most efficient when 150mg of MWCNTs with an outer diameter of less than 8nm and a length of 0.5-2μm was used. A mixture of acetonitrile/50mM ammonium acetate (95:5, v/v) was shown to be the most suitable solvent for desorbing the compounds from the MWCNTs. The proposed method was validated according to the European Commission Decision 2002/657/EC, which determines linearity, specificity, decision limit (CCα), detection capability (CCβ), recovery, precision and stability. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Application of multiwall carbon nanotubes-based matrix solid phase dispersion extraction for determination of hormones in butter by gas chromatography mass spectrometry.

    PubMed

    Su, Rui; Wang, Xinghua; Xu, Xu; Wang, Ziming; Li, Dan; Zhao, Xin; Li, Xueyuan; Zhang, Hanqi; Yu, Aimin

    2011-08-05

    The multiwall carbon nanotubes (MWCNTs)-based matrix solid phase dispersion (MSPD) was applied for the extraction of hormones, including 17-α-ethinylestradiol, 17-α-estradiol, estriol, 17-β-estradiol, estrone, medroxyprogesterone, progesterone and norethisterone acetate in butter samples. The method includes MSPD extraction of the target analytes from butter samples, derivatization of hormones with heptafluorobutyric acid anhydride-acetonitrile mixture, and determination by gas chromatography-mass spectrometry. The mixture containing 0.30 g graphitized MWCNTs and 0.10 g MWCNTs was selected as absorbent. Ethyl acetate was used as elution solvent. The elution solvent volume and flow rate were 12 mL and 0.9 mL min(-1), respectively. The recoveries of hormones obtained by analyzing the five spiked butter samples were from 84.5 to 111.2% and relative standard deviations from 1.9 to 8.9%. Limits of detection and quantification for determining the analytes were in the range of 0.2-1.3 and 0.8-4.5 μg kg(-1), respectively. Compared with other traditional methods, the proposed method is simpler in the operation and shorter in the sample pretreatment time. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Multi-instrumental characterization of carbon nanotubes dispersed in aqueous solutions

    EPA Science Inventory

    Previous studies showed that the dispersion extent and physicochemical properties of carbon nanotubes are highly dependent upon the preparation methods (e.g., dispersion methods and dispersants). In the present work, multiwalled carbon nanotubes (MWNTs) are dispersed in aqueous s...

  19. Exchange of Surfactant by Natural Organic Matter on the Surfaces of Multi-Walled Carbon Nanotubes

    EPA Science Inventory

    The increasing production and applications of multi-walled carbon nanotubes (MWCNTs) have elicited concerns regarding their release and potential adverse effects in the environment. To form stable aqueous MWCNTs suspensions, surfactants are often employed to facilitate dispersion...

  20. Calcium Alginate-Caged Multiwalled Carbon Nanotubes Dispersive Microsolid Phase Extraction Combined With Gas Chromatography-Flame Ionization Detection for the Determination of Polycyclic Aromatic Hydrocarbons in Water Samples.

    PubMed

    Abboud, Ayad Sami; Sanagi, Mohd Marsin; Ibrahim, Wan Aini Wan; Keyon, Aemi S Abdul; Aboul-Enein, Hassan Y

    2018-02-01

    In this study, caged calcium alginate-caged multiwalled carbon nanotubes dispersive microsolid phase extraction was described for the first time for the extraction of polycyclic aromatic hydrocarbons (PAHs) from water samples prior to gas chromatographic analysis. Fluorene, phenanthrene and fluoranthene were selected as model compounds. The caged calcium alginate-caged multiwalled carbon nanotubes was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and thermal gravimetry analyses. The effective parameters namely desorption solvent, solvent volume, extraction time, desorption time, the mass of adsorbent and sample volume were optimized. Under the optimum extraction conditions, the developed method showed good linearity in the range of 0.5-50 ng mL-1 (R2 ≥ 0.996), low limits of detection and quantification (0.42-0.22 ng mL-1) (0.73-1.38 ng mL-1) respectively, good relative recoveries (71.2-104.2%) and reproducibility (RSD 1.8-12.4%, n = 3) for the studied PAHs in water sample. With high enrichment factor (1,000), short extraction time (<30 min), low amounts of adsorbent (100 mg) and low amounts of solvent (0.1 mol) have proven that the microsolid phase extraction method based on calcium alginate-caged multiwalled carbon nanotubes are environmentally friendly and convenient extraction method to use as an alternative adsorbent in the simultaneous preconcentration of PAHs from environmental water samples. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. Rapid analysis of pesticide residues in drinking water samples by dispersive solid-phase extraction based on multiwalled carbon nanotubes and pulse glow discharge ion source ion mobility spectrometry.

    PubMed

    Zou, Nan; Gu, Kejia; Liu, Shaowen; Hou, Yanbing; Zhang, Jialei; Xu, Xiang; Li, Xuesheng; Pan, Canping

    2016-03-01

    An analytical method based on dispersive solid-phase extraction with a multiwalled carbon nanotubes sorbent coupled with positive pulse glow discharge ion mobility spectrometry was developed for analysis of 30 pesticide residues in drinking water samples. Reduced ion mobilities and the mass-mobility correlation of 30 pesticides were measured. The pesticides were divided into five groups to verify the separation capability of pulse glow discharge in mobility spectrometry. The extraction conditions such as desorption solvent, ionic strength, conditions of adsorption and desorption, the amounts of multiwalled carbon nanotubes, and solution pH were optimized. The enrichment factors of pesticides were 5.4- to 48.7-fold (theoretical enrichment factor was 50-fold). The detection limits of pesticides were 0.01∼0.77 μg/kg. The linear range was 0.005-0.2 mg/L for pesticide standard solutions, with determination coefficients from 0.9616 to 0.9999. The method was applied for the analysis of practical and spiked drinking water samples. All results were confirmed by high-performance liquid chromatography with tandem mass spectrometry. The proposed method was proven to be a commendably rapid screening qualitative and semiquantitative technique for the analysis of pesticide residues in drinking water samples on site. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Modification of polydopamine-coated Fe3O4 nanoparticles with multi-walled carbon nanotubes for magnetic-μ-dispersive solid-phase extraction of antiepileptic drugs in biological matrices.

    PubMed

    Zhang, Ruiqi; Wang, Siming; Yang, Ye; Deng, Yulan; Li, Di; Su, Ping; Yang, Yi

    2018-06-01

    In this study, multi-walled carbon nanotubes were coated on the surface of magnetic nanoparticles modified by polydopamine. The synthesized composite was characterized and applied to magnetic-μ-dispersive solid-phase extraction of oxcarbazepine (OXC), phenytoin (PHT), and carbamazepine (CBZ) from human plasma, urine, and cerebrospinal fluid samples prior to analysis by a high-performance liquid chromatography-photodiode array detector. The extraction parameters were investigated and the optimum condition was obtained when the variables were set to the following: sorbent type, Fe 3 O 4 @polyDA-MWCNTs (length < 2 μm); sample pH, 6; amount of sorbent, 15 mg; sorption time, 1.5 min at room temperature; type and volume of the eluent, 2.5 mL methanol; and salt content, none added. Under the optimized conditions, the calibration curves are linear in the concentration range 2-2000 ng/mL, the limits of detection are in the range 0.4-3.1 ng/mL, and the relative standard deviations and relative recoveries of plasma (spiked at 200 ng/mL) and CSF (spiked at 50 ng/mL) are in the ranges 1.4-8.2% and 92.8-96.5%, respectively. The applicability of the method was successfully confirmed by extraction and determination of OXC, PHT, and CBZ in biological matrices. Graphical abstract Magnetic multi-walled carbon nanotube core-shell composites were applied as magnetic-μ-dispersive solid-phase extraction adsorbents for determination of antiepileptic drugs in biological matrices.

  3. Ionic liquid-assisted multiwalled carbon nanotube-dispersive micro-solid phase extraction for sensitive determination of inorganic As species in garlic samples by electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Grijalba, Alexander Castro; Escudero, Leticia B.; Wuilloud, Rodolfo G.

    2015-08-01

    A highly sensitive dispersive micro-solid phase extraction (D-μ-SPE) method combining an ionic liquid (IL) and multi-walled carbon nanotubes (MWCNTs) for inorganic As species (As(III) and As(V)) species separation and determination in garlic samples by electrothermal atomic absorption spectrometry (ETAAS) was developed. Trihexyl(tetradecil)phosphonium chloride IL was used to form an ion pair with the arsenomolybdate complex obtained by reaction of As(V) with molybdate ion. Afterwards, 1.0 mg of MWCNTs was dispersed for As(V) extraction and the supernatant was separated by centrifugation. MWCNTs were re-dispersed with tetradecyltrimethylammonium bromide surfactant and ultrasound followed by direct injection into the graphite furnace of ETAAS for As determination. Pyrolysis and atomization conditions were carefully studied for complete decomposition of MWCNTs and IL matrices. Under optimum conditions, an extraction efficiency of 100% and a preconcentration factor of 70 were obtained with 5 mL of garlic extract. The detection limit was 7.1 ng L- 1 and the relative standard deviations (RSDs) for six replicate measurements at 5 μg L- 1 of As were 5.4% and 4.8% for As(III) and As(V), respectively. The proposed D-μ-SPE method allowed the efficient separation and determination of inorganic As species in a complex matrix such as garlic extract.

  4. Fabrication and Characterization of Multi-Walled Carbon Nanotube (MWCNT) and Ni-Coated Multi-Walled Carbon Nanotube (Ni-MWCNT) Repair Patches for Carbon Fiber Reinforced Composite Systems

    NASA Technical Reports Server (NTRS)

    Johnson, Brienne; Caraccio, Anne; Tate, LaNetra; Jackson, Dionne

    2011-01-01

    Multi-walled carbon nanotube (MWCNT)/epoxy and nickel-coated multi-walled carbon nanotube (Ni-MWCNT)/epoxy systems were fabricated into carbon fiber composite repair patches via vacuum resin infusion. Two 4 ply patches were manufactured with fiber orientations of [90/ 90/ 4590] and [0/90/ +45/ -45]. Prior to resin infusion, the MWCNT/Epoxy system and NiMWCNT/ epoxy systems were optimized for dispersion quality. Scanning electron microscopy (SEM) and optical microscopy (OM) were used to determine the presence ofcarbon nanotubes and assess dispersion quality. Decomposition temperatures were determined via thermogravametric analysis (TGA). SEM and TGA were also used to evaluate the composite repair patches.

  5. Efficient electrochemical degradation of multiwall carbon nanotubes.

    PubMed

    Reipa, Vytas; Hanna, Shannon K; Urbas, Aaron; Sander, Lane; Elliott, John; Conny, Joseph; Petersen, Elijah J

    2018-07-15

    As the production mass of multiwall carbon nanotubes (MWCNT) increases, the potential for human and environmental exposure to MWCNTs may also increase. We have shown that exposing an aqueous suspension of pristine MWCNTs to an intense oxidative treatment in an electrochemical reactor, equipped with an efficient hydroxyl radical generating Boron Doped Diamond (BDD) anode, leads to their almost complete mineralization. Thermal optical transmittance analysis showed a total carbon mass loss of over two orders of magnitude due to the electrochemical treatment, a result consistent with measurements of the degraded MWCNT suspensions using UV-vis absorbance. Liquid chromatography data excludes substantial accumulation of the low molecular weight reaction products. Therefore, up to 99% of the initially suspended MWCNT mass is completely mineralized into gaseous products such as CO 2 and volatile organic carbon. Scanning electron microscopy (SEM) images show sporadic opaque carbon clusters suggesting the remaining nanotubes are transformed into structure-less carbon during their electrochemical mineralization. Environmental toxicity of pristine and degraded MWCNTs was assessed using Caenorhabditis elegans nematodes and revealed a major reduction in the MWCNT toxicity after treatment in the electrochemical flow-by reactor. Published by Elsevier B.V.

  6. Aerosol generation and measurement of multi-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Myojo, Toshihiko; Oyabu, Takako; Nishi, Kenichiro; Kadoya, Chikara; Tanaka, Isamu; Ono-Ogasawara, Mariko; Sakae, Hirokazu; Shirai, Tadashi

    2009-01-01

    Mass production of some kinds of carbon nanotubes (CNT) is now imminent, but little is known about the risk associated with their exposure. It is important to assess the propensity of the CNT to release particles into air for its risk assessment. In this study, we conducted aerosolization of a multi-walled CNT (MWCNT) to assess several aerosol measuring instruments. A Palas RBG-1000 aerosol generator applied mechanical stress to the MWCNT by a rotating brush at feed rates ranging from 2 to 20 mm/h, which the MWCNT was fed to a two-component fluidized bed. The fluidized bed aerosol generator was used to disperse the MWCNT aerosol once more. We monitored the generated MWCNT aerosol concentrations based on number, area, and mass using a condensation particle counter and nanoparticle surface area monitor. Also we quantified carbon mass in MWCNT aerosol samples by a carbon monitor. The shape of aerosolized MWCNT fibers was observed by a scanning electron microscope (SEM). The MWCNT was well dispersed by our system. We found isolated MWCNT fibers in the aerosols by SEM and the count median lengths of MWCNT fibers were 4-6 μm. The MWCNT was quantified by the carbon monitor with a modified condition based on the NIOSH analytical manual. The MWCNT aerosol concentration (EC mass base) was 4 mg/m3 at 2 mm/h in this study.

  7. Multi-residue determination of 171 pesticides in cowpea using modified QuEChERS method with multi-walled carbon nanotubes as reversed-dispersive solid-phase extraction materials.

    PubMed

    Han, Yongtao; Song, Le; Zou, Nan; Chen, Ronghua; Qin, Yuhong; Pan, Canping

    2016-09-15

    A rapid and sensitive method for the determination of 171 pesticides in cowpea was developed using multi-walled carbon nanotubes (MWCNTs) as reversed-dispersive solid-phase (r-DSPE) extraction materials. The clean-up performance of MWCNTs was proved to be obviously superior to PSA and GCB. This method was validated on cowpea spiked at 0.01 and 0.1mgkg(-1) with five replicates. The mean recoveries for 169 pesticides ranged from 74% to 129% with relative standard deviations (RSDs) (n=5) lower than 16.4%, except diflufenican and quizalofop-ethyl. Good linearity for all pesticides was obtained with the calibration curve coefficients (R(2)) larger than 0.9970. The limit of detection (LODs) and limit of quantification (LOQs) for the 171 pesticides ranged from 0.001 to 0.003mgkg(-1) and from 0.002 to 0.009mgkg(-1), respectively. The method was demonstrated to be reliable and sensitive for the routine monitoring of the 171 pesticides in cowpea samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Multiwalled Carbon Nanotube Deposition on Model Environmental Surfaces

    EPA Science Inventory

    Deposition of multiwalled carbon nanotubes (MWNTs) on model environmental surfaces was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Deposition behaviors of MWNTs on positively and negatively charged surfaces were in good agreement with Der...

  9. 76 FR 26186 - Multi-Walled Carbon Nanotubes; Significant New Use Rule

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-06

    ... 2070-AB27 Multi-Walled Carbon Nanotubes; Significant New Use Rule AGENCY: Environmental Protection... as multi-walled carbon nanotubes (MWCNT) which was the subject of premanufacture notice (PMN) P-08... (due to confidentiality claims) as multi-walled carbon nanotubes (PMN P-08-199). This action requires...

  10. 40 CFR 721.10183 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10183 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-199) is subject to reporting under this section for the...

  11. 40 CFR 721.10155 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10155 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-177) is subject to reporting under this section for the...

  12. 40 CFR 721.10183 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10183 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-199) is subject to reporting under this section for the...

  13. 40 CFR 721.10155 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10155 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-177) is subject to reporting under this section for the...

  14. 40 CFR 721.10663 - Functionalized multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Specific Chemical Substances § 721.10663 Functionalized multi-walled carbon nanotubes (generic). (a... generically as functionalized multi-walled carbon nanotubes (PMN P-12-44) is subject to reporting under this... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Functionalized multi-walled carbon...

  15. 40 CFR 721.10663 - Functionalized multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Specific Chemical Substances § 721.10663 Functionalized multi-walled carbon nanotubes (generic). (a... generically as functionalized multi-walled carbon nanotubes (PMN P-12-44) is subject to reporting under this... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Functionalized multi-walled carbon...

  16. 40 CFR 721.10183 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10183 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-199) is subject to reporting under this section for the...

  17. 40 CFR 721.10155 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10155 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-177) is subject to reporting under this section for the...

  18. 40 CFR 721.10183 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10183 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-199) is subject to reporting under this section for the...

  19. 40 CFR 721.10155 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes (generic... Specific Chemical Substances § 721.10155 Multi-walled carbon nanotubes (generic). (a) Chemical substance... multi-walled carbon nanotubes (PMN P-08-177) is subject to reporting under this section for the...

  20. Free vibration of multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, C. Y.; Ru, C. Q.; Mioduchowski, A.

    2005-06-01

    A multiple-elastic shell model is applied to systematically study free vibration of multiwall carbon nanotubes (MWNTs). Using Flugge [Stresses in Shells (Springer, Berlin, 1960)] equations of elastic shells, vibrational frequencies and associated modes are calculated for MWNTs of innermost radii 5 and 0.65 nm, respectively. The emphasis is placed on the effect of interlayer van der Waals (vdW) interaction on free vibration of MWNTs. Our results show that the interlayer vdW interaction has a crucial effect on radial (R) modes of large-radius MWNTs (e.g., of the innermost radius 5 nm), but is less pronounced for R modes of small-radius MWNTs (e.g., of the innermost radius 0.65 nm), and usually negligible for torsional (T) and longitudinal (L) modes of MWNTs. This is attributed to the fact that the interlayer vdW interaction, characterized by a radius-independent vdW interaction coefficient, depends on radial deflections only, and is dominant only for large-radius MWNTs of lower radial rigidity but less pronounced for small-radius MWNTs of much higher radial rigidity. As a result, the R modes of large-radius MWNTs are typically collective motions of almost all nested tubes, and the R modes of small-radius MWNTs, as well as the T and L modes of MWNTs, are basically vibrations of individual tubes. In particular, an approximate single-shell model is suggested to replace the multiple-shell model in calculating the lowest frequency of R mode of thin MWNTs (defined by the innermost radius-to-thickness ratio not less than 4) with relative errors less than 10%. In addition, the simplified Flugge single equation is adopted to substitute the exact Flugge equations in determining the R-mode frequencies of MWNTs with relative errors less than 10%.

  1. Electrical conductivity of multi-walled carbon nanotubes-SU8 epoxy composites

    NASA Astrophysics Data System (ADS)

    Grimaldi, Claudio; Mionić, Marijana; Gaal, Richard; Forró, László; Magrez, Arnaud

    2013-06-01

    We have characterized the electrical conductivity of the composite which consists of multi-walled carbon nanotubes dispersed in SU8 epoxy resin. Depending on the processing conditions of the epoxy (ranging from non-polymerized to cross-linked), we obtained tunneling and percolating-like regimes of the electrical conductivity of the composites. We interpret the observed qualitative change of the conductivity behavior in terms of reduced separation between the nanotubes induced by polymerization of the epoxy matrix.

  2. Photothermal therapy of melanoma tumor using multiwalled carbon nanotubes.

    PubMed

    Sobhani, Zahra; Behnam, Mohammad Ali; Emami, Farzin; Dehghanian, Amirreza; Jamhiri, Iman

    2017-01-01

    Photothermal therapy (PTT) is a therapeutic method in which photon energy is transformed into heat rapidly via different operations to extirpate cancer. Nanoparticles, such as carbon nanotubes (CNTs) have exceptional optical absorbance in visible and near infrared spectra. Therefore, they could be a good converter to induce hyperthermia in PTT technique. In our study, for improving the dispersibility of multiwalled CNTs in water, the CNTs were oxidized (O-CNTs) and then polyethylene glycol (PEG) was used for wrapping the surface of nanotubes. The formation of a thin layer of PEG around the nanotubes was confirmed through Fourier transform infrared, thermogravimetric analysis, and field emission scanning electron microscopy techniques. Results of thermogravimetric analysis showed that the amount of PEG component in the O-CNT-PEG was approximately 80% (w/w). Cell cytotoxicity study showed that O-CNT was less cytotoxic than pristine multiwalled nanotubes, and O-CNT-PEG had the lowest toxicity against HeLa and HepG2 cell lines. The effect of O-CNT-PEG in reduction of melanoma tumor size after PTT was evaluated. Cancerous mice were exposed to a continuous-wave near infrared laser diode (λ=808 nm, P =2 W and I =8 W/cm 2 ) for 10 minutes once in the period of the treatment. The average size of tumor in mice receiving O-CNT-PEG decreased sharply in comparison with those that received laser therapy alone. Results of animal studies indicate that O-CNT-PEG is a powerful candidate for eradicating solid tumors in PTT technique.

  3. Heat dissipation for microprocessor using multiwalled carbon nanotubes based liquid.

    PubMed

    Hung Thang, Bui; Trinh, Pham Van; Chuc, Nguyen Van; Khoi, Phan Hong; Minh, Phan Ngoc

    2013-01-01

    Carbon nanotubes (CNTs) are one of the most valuable materials with high thermal conductivity (2000 W/m · K compared with thermal conductivity of Ag 419 W/m · K). This suggested an approach in applying the CNTs in thermal dissipation system for high power electronic devices, such as computer processor and high brightness light emitting diode (HB-LED). In this work, multiwalled carbon nanotubes (MWCNTs) based liquid was made by COOH functionalized MWCNTs dispersed in distilled water with concentration in the range between 0.2 and 1.2 gram/liter. MWCNT based liquid was used in liquid cooling system to enhance thermal dissipation for computer processor. By using distilled water in liquid cooling system, CPU's temperature decreases by about 10°C compared with using fan cooling system. By using MWCNT liquid with concentration of 1 gram/liter MWCNTs, the CPU's temperature decreases by 7°C compared with using distilled water in cooling system. Theoretically, we also showed that the presence of MWCNTs reduced thermal resistance and increased the thermal conductivity of liquid cooling system. The results have confirmed the advantages of the MWCNTs for thermal dissipation systems for the μ -processor and other high power electronic devices.

  4. Environmental aging and degradation of multiwalled carbon nanotube reinforced polypropylene

    EPA Science Inventory

    The degradation of polypropylene (PP) and PP-multiwalled carbon nanotube (PP-MWCNT) panels during environmental weathering resulted in an increased degree of crystallinity, making them brittle, and creating surface cracks. The degradation led to a breakdown of the panels and incr...

  5. Biological Sensors Using DNA Functionalized Multiwalled Carbon Nanotubes

    DTIC Science & Technology

    2009-10-01

    BIOLOGICAL SENSORS USING DNA FUNCTIONALIZED MULTIWALLED CARBON NANOTUBES S. Ganguly, A. Leela Mohana Reddy and S. Ramaprabhu Alternative...Braun, E. Science 2003, 302, 1380. 9. Leela Mohana Reddy, A.; Shaijumon, M. M.; Ramaprabhu, S. Nanotechnology 2006, 17, 5299. 10. Kovtyukhova, N

  6. Preparation and Characterization of PETI-330/Multiwalled Carbon Nanotube

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Working, Dennis C.; Criss, Jim M.; Siochi, Emilie J.; Connell, John W.

    2005-01-01

    As part of an ongoing effort to incorporate multifunctionality into advanced composites, blends of PETI-330 and multi-walled carbon nanotubes (MWCNTs) were prepared, characterized and fabricated into moldings. The PETI-330/MWCNT mixtures were prepared at concentrations ranging from 3 to 25 weight percent by dry mixing the components in a ball mill. The resulting powders were characterized for degree of mixing, thermal and rheological properties. Based on the characterization results, PETI-330/MWCNT samples were scaled up to 300 g and used to fabricate moldings 10.2 cm x 15.2 cm x 0.32 cm thick. The moldings were made by injecting the mixtures at 260-280 C into an Invar tool followed by curing for 1 h at 371 C. The tool was designed to impart shear during the injection process in an attempt to achieve some alignment of the MWCNTs in the flow direction. Good quality moldings were obtained that were subsequently characterized for thermal, mechanical and electrical properties. The degree of dispersion and alignment of the MWCNTs were investigated using high-resolution scanning electron microscopy. The preparation and preliminary characterization of PETI-330/MWCNT composites will be discussed. Keywords: phenylethynyl terminated imides, high temperature polymers, nanocomposites, moldings

  7. Preparation and Characterization of PETI-330/Multiwalled Carbon Nanotube Composites

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Working, Dennis C.; Delozier, Donavon M.; Criss, Jim M.; Siochi, Emilie J.; Connell, John W.

    2005-01-01

    As part of an ongoing effort to incorporate multi-functionality into advanced composites, blends of PETI-330 and multi-walled carbon nanotubes (MWCNTs) were prepared, characterized and fabricated into moldings. The PETI-330/MWCNT mixtures were prepared at concentrations ranging from 3 to 25 weight percent by dry mixing the components in a ball mill. The resulting powders were characterized for degree of mixing, thermal and rheological properties. Based on the characterization results, PETI-330/MWCNT samples were scaled up to approx. 300 g and used to fabricate moldings 10.2 cm x 15.2 cm x 0.32 cm thick. The moldings were fabricated by injecting the mixtures at 260-280 C into a stainless steel tool followed by curing for 1 h at 371 C. The tool was designed to impart high shear during the injection process in an attempt to achieve some alignment of the MWCNTs in the flow direction. Good quality moldings were obtained that were subsequently characterized for thermal, mechanical and electrical properties. The degree of dispersion and alignment of the MWCNTs were investigated using high-resolution scanning electron microscopy and Raman spectroscopy. The preparation and preliminary characterization of PETI-330/MWCNT composites will be discussed. Keywords: phenylethynyl terminated imides, high temperature polymers, nanocomposites,

  8. Spectroscopic investigations on oxidized multi-walled carbon nanotubes

    SciTech Connect

    Anandhi, C. M. S.; Premkumar, S.; Asath, R. Mohamed

    2016-05-06

    The pristine multi-walled carbon nanotubes (MWCNTs) were oxidized by the ultrasonication process. The oxidized MWCNTs were characterized by the X-ray diffraction (XRD), ultraviolet–visible (UV-Vis) and Fourier transform -Raman (FT-Raman) spectroscopic techniques. The XRD analysis confirms that the oxidized MWCNTs exist in a hexagonal structure and the sharp XRD peak corresponds to the (002) Bragg’s reflection plane, which indicates that the MWCNTs have higher crystalline nature. The UV-Vis analysis confirms that the MWCNTs functionalized with the carboxylic acid. The red shift was observed corresponds to the D band in the Raman spectrum, which reveals that the reduced disordered graphitic structure ofmore » oxidized MWCNTs. The strong Raman peak was observed at 2563 cm{sup -1} corresponds to the overtone of the D band, which is the characteristic vibrational mode of oxidized MWCNTs. The carboxylic acid functionalization of MWCNTs enhances the dispersibility, which paves the way for potential applications in the field of biosensors and targeted drug delivery.« less

  9. Preparation of supported electrocatalyst comprising multiwalled carbon nanotubes

    DOEpatents

    Wu, Gang; Zelenay, Piotr

    2013-08-27

    A process for preparing a durable non-precious metal oxygen reduction electrocatalyst involves heat treatment of a ball-milled mixture of polyaniline and multiwalled carbon nanotubes in the presence of a Fe species. The catalyst is more durable than catalysts that use carbon black supports. Performance degradation was minimal or absent after 500 hours of operation at constant cell voltage of 0.40 V.

  10. Electrical Conductivity in Polymer Blends/ Multiwall Carbon Nanotubes

    SciTech Connect

    Kulkarni, Ajit R.; Bose, Suryasarathi; Bhattacharyya, Arup R.

    2008-10-23

    Carbon nanotubes (CNT) based polymer composites have emerged as the future multifunctional materials in view of its exceptional mechanical, thermal and electrical properties. One of the major interests is to develop conductive polymer composites preferably at low concentration of CNT utilizing their high aspect ratio (L/D) for numerous applications, which include antistatic devices, capacitors and materials for EMI shielding. In this context, polymer blends have emerged as a potential candidate in lowering the percolation thresholds further by the utilization of 'double-percolation' which arises from the synergistic improvements in blend properties associated with the co-continuous morphology. Due to strong inter-tube vanmore » der Waals' forces, they often tend to aggregate and uniform dispersion remains a challenge. To overcome this challenge, we exploited sodium salt of 6-aminohexanoic acid (Na-AHA) which was able to assist in debundlling the multiwall carbon nanotubes (MWNT) through 'cation-{pi}' interactions during melt-mixing leading to percolative 'network-like' structure of MWNT within polyamide6 (PA6) phase in co-continuous PA6/acrylonitrile butadiene styrene (ABS) blends. The composite exhibited low electrical percolation thresholds of 0.25 wt% of MWNT, the lowest reported value in this system so far. Retention of 'network-like structure' in the solid state with significant refinement was observed even at lower MWNT concentration in presence Na-AHA, which was assessed through AC electrical conductivity measurements. Reactive coupling was found to be a dominant factor besides 'cation-{pi}' interactions in achieving low electrical percolation in PA6/ABS+MWNT composites.« less

  11. Electrical Conductivity in Polymer Blends/ Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kulkarni, Ajit R.; Bose, Suryasarathi; Bhattacharyya, Arup R.

    2008-10-01

    Carbon nanotubes (CNT) based polymer composites have emerged as the future multifunctional materials in view of its exceptional mechanical, thermal and electrical properties. One of the major interests is to develop conductive polymer composites preferably at low concentration of CNT utilizing their high aspect ratio (L/D) for numerous applications, which include antistatic devices, capacitors and materials for EMI shielding. In this context, polymer blends have emerged as a potential candidate in lowering the percolation thresholds further by the utilization of `double-percolation' which arises from the synergistic improvements in blend properties associated with the co-continuous morphology. Due to strong inter-tube van der Waals' forces, they often tend to aggregate and uniform dispersion remains a challenge. To overcome this challenge, we exploited sodium salt of 6-aminohexanoic acid (Na-AHA) which was able to assist in debundlling the multiwall carbon nanotubes (MWNT) through `cation-π' interactions during melt-mixing leading to percolative `network-like' structure of MWNT within polyamide6 (PA6) phase in co-continuous PA6/acrylonitrile butadiene styrene (ABS) blends. The composite exhibited low electrical percolation thresholds of 0.25 wt% of MWNT, the lowest reported value in this system so far. Retention of `network-like structure' in the solid state with significant refinement was observed even at lower MWNT concentration in presence Na-AHA, which was assessed through AC electrical conductivity measurements. Reactive coupling was found to be a dominant factor besides `cation-π' interactions in achieving low electrical percolation in PA6/ABS+MWNT composites.

  12. High-efficiency surfactant prepared from phenolic resin for multi-walled carbon nanotube aqueous suspension

    NASA Astrophysics Data System (ADS)

    Li, Yutong; Wei, Haixu; Li, Lizhi; Wang, Jie; Qian, Xin; He, Liu; Wang, Xuefei; Ouyang, Qin; Chen, Yousi; Zhang, Yonggang; Li, Yong

    2018-06-01

    Carbon nanotubes (CNTs) have been widely exploited to be used in many fields due to its perfect mechanical properties, but CNT agglomerates severely prevent CNTs' excellent properties from performing. Many dispersants were synthesized to resolve the difficulty reported in recent years. In this paper, a healthier and cheaper dispersant with phenolic resin as original reagent was synthesized (denoted as AEP-4). Fourier transform infrared spectroscopy, nuclear magnetic resonance, and mass spectra were carried out to characterize chemical structure of reagent and products. Ultraviolet-visible spectroscopy and transmission electron microscopy were employed to evaluate the dispersibility of multi-walled carbon nanotubes (MWCNTs) in aqueous solution. The results showed that AEP-4 containing tertiary ammonium cations exhibited strong ability to disperse MWCNTs in aqueous solution, which showed better dispersion ability than sodium dodecyl benzene sulfonate. The scanning electron microscope results of MWCNT/carbon fiber reinforcements showed that many single MWCNTs showed up and uniformly covered carbon fiber surface in the case of carbon fiber treated by MWCNT/AEP-4 suspension, which reflected that MWCNT suspension with AEP-4 had good dispersion.

  13. Tensile Yielding of Multi-Wall Carbon Nanotube

    NASA Technical Reports Server (NTRS)

    Wei, Chenyu; Cho, Kyeongjae; Srivastava, Deepak; Parks, John W. (Technical Monitor)

    2002-01-01

    The tensile yielding of multiwall carbon nanotubes (MWCNTs) has been studied using Molecular Dynamics simulations and a Transition State Theory based model. We find a strong dependence of the yielding on the strain rate. A critical strain rate has been predicted above/below which yielding strain of a MWCNT is larger/smaller than that of the corresponding single-wall carbon nanotubes. At experimentally feasible strain rate of 1% /hour and T = 300K, the yield strain of a MWCNT is estimated to be about 3-4 % higher than that of an equivalent SWCNT (Single Wall Carbon Nanotube), in good agreement with recent experimental observations.

  14. Explosive compaction of aluminum oxide modified by multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Buzyurkin, A. E.; Kraus, E. I.; Lukyanov, Ya L.

    2018-04-01

    This paper presents experiments and numerical research on explosive compaction of aluminum oxide powder modified by multiwall carbon nanotubes (MWCNT) and modeling of the stress state behind the shock front at shock loading. The aim of this study was to obtain a durable low-porosity compact sample. The explosive compaction technology is used in this problem because the aluminum oxide is an extremely hard and refractory material. Therefore, its compaction by traditional methods requires special equipment and considerable expenses.

  15. Vertically aligned multiwalled carbon nanotubes as electronic interconnects

    NASA Astrophysics Data System (ADS)

    Gopee, Vimal Chandra

    The drive for miniaturisation of electronic circuits provides new materials challenges for the electronics industry. Indeed, the continued downscaling of transistor dimensions, described by Moore’s Law, has led to a race to find suitable replacements for current interconnect materials to replace copper. Carbon nanotubes have been studied as a suitable replacement for copper due to its superior electrical, thermal and mechanical properties. One of the advantages of using carbon nanotubes is their high current carrying capacity which has been demonstrated to be three orders of magnitude greater than that of copper. Most approaches in the implementation of carbon nanotubes have so far focused on the growth in vias which limits their application. In this work, a process is described for the transfer of carbon nanotubes to substrates allowing their use for more varied applications. Arrays of vertically aligned multiwalled carbon nanotubes were synthesised by photo-thermal chemical vapour deposition with high growth rates. Raman spectroscopy was used to show that the synthesised carbon nanotubes were of high quality. The carbon nanotubes were exposed to an oxygen plasma and the nature of the functional groups present was determined using X-ray photoelectron spectroscopy. Functional groups, such as carboxyl, carbonyl and hydroxyl groups, were found to be present on the surface of the multiwalled carbon nanotubes after the functionalisation process. The multiwalled carbon nanotubes were metallised after the functionalisation process using magnetron sputtering. Two materials, solder and sintered silver, were chosen to bind carbon nanotubes to substrates so as to enable their transfer and also to make electrical contact. The wettability of solder to carbon nanotubes was investigated and it was demonstrated that both functionalisation and metallisation were required in order for solder to bond with the carbon nanotubes. Similarly, functionalisation followed by metallisation

  16. The hepatotoxicity of multi-walled carbon nanotubes in mice

    NASA Astrophysics Data System (ADS)

    Ji, Zongfei; Zhang, Danying; Li, Ling; Shen, Xizhong; Deng, Xiaoyong; Dong, Ling; Wu, Minhong; Liu, Yuanfang

    2009-11-01

    The hepatotoxicity of two types of multi-walled carbon nanotubes (MWCNTs), acid-oxidized MWCNTs (O-MWCNTs) and Tween-80-dispersed MWCNTs (T-MWCNTs), were investigated with Kunming mice exposed to 10 and 60 mg kg-1 by intravenous injection for 15 and 60 d. Compared with the PBS group, the body-weight gain of the mice decreased and the level of total bilirubin and aspartate aminotransferase increased in the MWCNT-exposed group with a significant dose-effect relationship, while tumor necrosis factor alpha level did not show significant statistical change within 60 d. Spotty necrosis, inflammatory cell infiltration in portal region, hepatocyte mitochondria swelling and lysis were observed with a significant dose-effect relationship in the MWCNT groups. Liver damage of the T-MWCNT group was more severe than that of the O-MWCNT group according to the Roenigk classification system. Furthermore, T-MWCNTs induce slight liver oxidative damage in mice at 15 d, which was recovered at 60 d. Part of the gene expressions of mouse liver in the MWCNT groups changed compared to the PBS group, including GPCRs (G protein-coupled receptors), cholesterol biosynthesis, metabolism by cytochrome P450, natural-killer-cell-mediated cytotoxicity, TNF- α, NF-κB signaling pathway, etc. In the P450 pathway, the gene expressions of Gsta2 (down-regulated), Cyp2B19 (up-regulated) and Cyp2C50 (down-regulated) had significant changes in the MWCNT groups. These results show that a high dose of T-MWCNTs can induce hepatic toxicity in mice while O-MWCNTs seem to have less toxicity.

  17. Nanostructured copper phthalocyanine-sensitized multiwall carbon nanotube films.

    PubMed

    Hatton, Ross A; Blanchard, Nicholas P; Stolojan, Vlad; Miller, Anthony J; Silva, S Ravi P

    2007-05-22

    We report a detailed study of the interaction between surface-oxidized multiwall carbon nanotubes (o-MWCNTs) and the molecular semiconductor tetrasulfonate copper phthalocyanine (TS-CuPc). Concentrated dispersions of o-MWCNT in aqueous solutions of TS-CuPc are stable toward nanotube flocculation and exhibit spontaneous nanostructuring upon rapid drying. In addition to hydrogen-bonding interactions, the compatibility between the two components is shown to result from a ground-state charge-transfer interaction with partial charge transfer from o-MWCNT to TS-CuPc molecules orientated such that the plane of the macrocycle is parallel to the nanotube surface. The electronegativity of TS-CuPc as compared to unsubsubtituted copper phthalocyanine is shown to result from the electron-withdrawing character of the sulfonate substituents, which increase the molecular ionization potential and promote cofacial molecular aggregation upon drying. Upon spin casting to form uniform thin films, the experimental evidence is consistent with an o-MWCNT scaffold decorated with phthalocyanine molecules self-assembled into extended aggregates reminiscent of 1-D linearly stacked phthalocyanine polymers. Remarkably, this self-organization occurs in a fraction of a second during the spin-coating process. To demonstrate the potential utility of this hybrid material, it is successfully incorporated into a model organic photovoltaic cell at the interface between a poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester bulk heterojunction layer and an indium-tin oxide-coated glass electrode to increase the light-harvesting capability of the device and facilitate hole extraction. The resulting enhancement in power conversion efficiency is rationalized in terms of the electronic, optical, and morphological properties of the nanostructured thin film.

  18. Wetting behavior of multi-walled carbon nanotube nanofluids

    NASA Astrophysics Data System (ADS)

    Karthikeyan, A.; Coulombe, S.; Kietzig, A. M.

    2017-03-01

    Nanofluids—engineered colloidal suspensions in base liquids—have captivated the interest of researchers over the last two decades for various existing as well as emerging technological applications. The main impetus for the synthesis of such novel nanocomposite liquids is the potential to alter properties of the base liquid, such as its viscosity, thermal conductivity, and surface tension, and to introduce specific optical and magnetic properties. Numerous studies suggest trends and explanations for the effects associated with the addition of nanoparticles, and that deviation from the base liquid properties are dependent on nanoparticle concentration. However, there remains a certain ambiguity in the available literature. The wetting behavior and surface tension of nanofluids are particular examples where highly conflicting results exist. In this study, we used multi-walled carbon nanotubes (MWCNTs) functionalized by plasma treatment and dispersed in reverse osmosis water and 99% anhydrous ethanol. Our observations reveal that the surface tension and wetting behavior of the stable aqueous and ethanol-based nanofluids containing plasma functionalized MWCNTs are unaffected by the MWCNT loading up to 120 (0.012) and ∼210 (0.021) ppm (vol%), respectively. The ethanol-based MWCNT nanofluids allowed us to extend the study to higher loadings, and a linear increase of the surface tension past ∼200 ppm was observed. Conversely, nanofluids containing non-functionalized or surfactant-stabilized MWCNTs show drastically different contact angle values when compared to the base liquids even at very low concentrations (less than 100 ppm). We demonstrate that the stability of nanofluid and method of stabilization are crucial parameters in determining the wetting behavior of nanofluids.

  19. Adsorption of selected volatile organic vapors on multiwall carbon nanotubes.

    PubMed

    Shih, Yang-hsin; Li, Mei-syue

    2008-06-15

    Carbon nanotubes are expected to play an important role in sensing, pollution treatment and separation techniques. This study examines the adsorption behaviors of volatile organic compounds (VOCs), n-hexane, benzene, trichloroethylene and acetone on two multiwall carbon nanotubes (MWCNTs), CNT1 and CNT2. Among these VOCs, acetone exhibits the highest adsorption capacity. The highest adsorption enthalpies and desorption energies of acetone were also observed. The strong chemical interactions between acetone and both MWCNTs may be the result from chemisorption on the topological defects. The adsorption heats of trichloroethylene, benzene, and n-hexane are indicative of physisorption on the surfaces of both MWCNTs. CNT2 presents a higher adsorption capacity than CNT1 due to the existence of an exterior amorphous carbon layer on CNT2. The amorphous carbon enhances the adsorption capacity of organic chemicals on carbon nanotubes. The morphological and structure order of carbon nanotubes are the primary affects on the adsorption process of organic chemicals.

  20. Electronic structure of multi-walled carbon fullerenes

    NASA Astrophysics Data System (ADS)

    Doore, Keith; Cook, Matthew; Clausen, Eric; Lukashev, Pavel V.; Kidd, Tim E.; Stollenwerk, Andrew J.

    2017-02-01

    Despite an enormous amount of research on carbon based nanostructures, relatively little is known about the electronic structure of multi-walled carbon fullerenes, also known as carbon onions. In part, this is due to the very high computational expense involved in estimating electronic structure of large molecules. At the same time, experimentally, the exact crystal structure of the carbon onion is usually unknown, and therefore one relies on qualitative arguments only. In this work we present the results of a computational study on a series of multi-walled fullerenes and compare their electronic structures to experimental data. Experimentally, the carbon onions were fabricated using ultrasonic agitation of isopropanol alcohol and deposited onto the surface of highly ordered pyrolytic graphite using a drop cast method. Scanning tunneling microscopy images indicate that the carbon onions produced using this technique are ellipsoidal with dimensions on the order of 10 nm. The majority of differential tunneling spectra acquired on individual carbon onions are similar to that of graphite with the addition of molecular-like peaks, indicating that these particles span the transition between molecules and bulk crystals. A smaller, yet sizable number exhibited a semiconducting gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) levels. These results are compared with the electronic structure of different carbon onion configurations calculated using first-principles. Similar to the experimental results, the majority of these configurations are metallic with a minority behaving as semiconductors. Analysis of the configurations investigated here reveals that each carbon onion exhibiting an energy band gap consisted only of non-metallic fullerene layers, indicating that the interlayer interaction is not significant enough to affect the total density of states in these structures.

  1. 75 FR 44198 - Proposed Significant New Use Rule for Multi-walled Carbon Nanotubes; Reopening of Comment Period

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-28

    ... Proposed Significant New Use Rule for Multi-walled Carbon Nanotubes; Reopening of Comment Period AGENCY... (SNUR) for the chemical substance identified generically as multi-walled carbon nanotubes (P-08-199). In... identified generically as multi-walled carbon nanotubes as identified in Premanufacture Notice (PMN) P-08-199...

  2. Applications of multi-walled carbon nanotube in electronic packaging

    PubMed Central

    2012-01-01

    Thermal management of integrated circuit chip is an increasing important challenge faced today. Heat dissipation of the chip is generally achieved through the die attach material and solders. With the temperature gradients in these materials, high thermo-mechanical stress will be developed in them, and thus they must also be mechanically strong so as to provide a good mechanical support to the chip. The use of multi-walled carbon nanotube to enhance the thermal conductivity, and the mechanical strength of die attach epoxy and Pb-free solder is demonstrated in this work. PMID:22405035

  3. Localized plasmon resonance in boron-doped multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Shuba, M. V.; Yuko, D. I.; Kuzhir, P. P.; Maksimenko, S. A.; Chigir, G. G.; Pyatlitski, A. N.; Sedelnikova, O. V.; Okotrub, A. V.; Lambin, Ph.

    2018-05-01

    Substitutionally boron-doped multiwalled carbon nanotubes (B-CNTs) with lengths mainly less than 0.5 μ m and diameters 10-30 nm have been obtained by arc-discharge evaporation of the graphite anode containing boron material. The broad peak has been observed in the midinfrared conductivity spectra of the thin film comprising B-CNTs. The peak was suggested to be associated with a phenomenon known as localized plasmon resonance. Theoretical analysis has been done to confirm the possibility of this phenomenon to occur in the B-CNTs.

  4. Plasma-enhanced chemical vapor deposition of multiwalled carbon nanofibers

    NASA Technical Reports Server (NTRS)

    Matthews, Kristopher; Cruden, Brett A.; Chen, Bin; Meyyappan, M.; Delzeit, Lance

    2002-01-01

    Plasma-enhanced chemical vapor deposition is used to grow vertically aligned multiwalled carbon nanofibers (MWNFs). The graphite basal planes in these nanofibers are not parallel as in nanotubes; instead they exhibit a small angle resembling a stacked cone arrangement. A parametric study with varying process parameters such as growth temperature, feedstock composition, and substrate power has been conducted, and these parameters are found to influence the growth rate, diameter, and morphology. The well-aligned MWNFs are suitable for fabricating electrode systems in sensor and device development.

  5. Plasma-enhanced chemical vapor deposition of multiwalled carbon nanofibers.

    PubMed

    Matthews, Kristopher; Cruden, Brett A; Chen, Bin; Meyyappan, M; Delzeit, Lance

    2002-10-01

    Plasma-enhanced chemical vapor deposition is used to grow vertically aligned multiwalled carbon nanofibers (MWNFs). The graphite basal planes in these nanofibers are not parallel as in nanotubes; instead they exhibit a small angle resembling a stacked cone arrangement. A parametric study with varying process parameters such as growth temperature, feedstock composition, and substrate power has been conducted, and these parameters are found to influence the growth rate, diameter, and morphology. The well-aligned MWNFs are suitable for fabricating electrode systems in sensor and device development.

  6. Fabrication of antibacterial PVA nanocomposite films containing dendritic polymer functionalized multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sapalidis, Andreas; Sideratou, Zili; Panagiotaki, Katerina N.; Sakellis, Elias; Kouvelos, Evangelos P.; Papageorgiou, Sergios; Katsaros, Fotios

    2018-03-01

    A series of Poly(vinyl alcohol) (PVA) nanocomposite films containing quaternized hyperbranched polyethyleneimine (PEI) functionalized multi-walled carbon nanotubes (ox-CNTs@QPEI) are prepared by solvent casting technique. The modified carbon based material exhibits high aqueous solubility, due to the hydrophilic character of the functionalized hyperbranched dendritic polymer. The quaternized PEI successfully wraps around nanotube walls, as polycations provide electrostatic repulsion. Various contents of ox-CNTs@QPEI ranging from 0.05 to 1.0 % w/w were employed to prepare functionalized PVA nanocomposites. The developed films exhibit adequate optical transparency, improved mechanical properties and extremely high antibacterial behavior due to the excellent dispersion of the functionalized carbon nanotubes into the PVA matrix.

  7. Hot wire production of single-wall and multi-wall carbon nanotubes

    DOEpatents

    Dillon, Anne C.; Mahan, Archie H.; Alleman, Jeffrey L.

    2010-10-26

    Apparatus (210) for producing a multi-wall carbon nanotube (213) may comprise a process chamber (216), a furnace (217) operatively associated with the process chamber (216), and at least one filament (218) positioned within the process chamber (216). At least one power supply (220) operatively associated with the at least one filament (218) heats the at least one filament (218) to a process temperature. A gaseous carbon precursor material (214) operatively associated with the process chamber (216) provides carbon for forming the multi-wall carbon nanotube (213). A metal catalyst material (224) operatively associated with the process (216) catalyzes the formation of the multi-wall carbon nanotube (213).

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

    PubMed

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

    2016-07-07

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

  9. Adsorption of emerging pollutants on functionalized multiwall carbon nanotubes.

    PubMed

    Patiño, Yolanda; Díaz, Eva; Ordóñez, Salvador; Gallegos-Suarez, Esteban; Guerrero-Ruiz, Antonio; Rodríguez-Ramos, Inmaculada

    2015-10-01

    Adsorption of three representative emerging pollutants - 1,8-dichlorooctane, nalidixic acid and 2-(4-methylphenoxy)ethanol- on different carbon nanotubes was studied in order to determine the influence of the morphological and chemical properties of the materials on their adsorption properties. As adsorbents, multiwall carbon nanotubes (MWCNTs) without functionalization and with oxygen or nitrogen surface groups, as well as carbon nanotubes doped with nitrogen were used. The adsorption was studied in aqueous phase using batch adsorption experiments, results being fitted to both Langmuir and Freundlich models. The adsorption capacity is strongly dependent on both the hydrophobicity of the adsorbates and the morphology of the adsorbents. Thermodynamic parameters were determined observing strong interactions between the aromatic rings of the emerging pollutant and the nitrogen modified adsorbents. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Temperature dependent Raman investigation of multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Dilawar Sharma, Nita; Singh, Jasveer; Vijay, Aditi

    2018-04-01

    We report anomalous observations in our investigations of the temperature dependent Raman spectroscopic measurement of multiwall carbon nanotubes. The Micro-Raman spectra were recorded with the laser source having 514.5 nm wavelength and within the temperature range of 80-440 K. The major Raman bands, the G and D band, are observed at 1584 and 1348 cm-1, respectively, at ambient. The absence of the radial breathing mode confirms the multiwall nature of carbon nanotubes. It has been observed that with an increase in the temperature above 120 K, there is a shift in Raman bands towards the higher wave-number region. However, a drop in the G and D bands is observed from 80 to 120 K which was not observed for the second order band. Thereafter, all Raman modes exhibited mode hardening up to about 320 K followed by mild softening of the phonon modes. Linear temperature coefficients were found to have higher contribution to mode hardening as compared to higher order terms. Total anharmonicity estimation shows a predominant effect of the quasi-harmonic term as compared to the true anharmonic term.

  11. Solid Lubrication by Multiwalled Carbon Nanotubes in Air and in Vacuum for Space and Aeronautics Applications

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Street, Kenneth W., Jr.; Andraws, Rodney; Jacques, David; VanderWal, Randy L.; Sayir, Ali

    2005-01-01

    To evaluate recently developed aligned multiwalled carbon nanotubes (MWNTs) and dispersed MWNTs for solid lubrication applications, unidirectional sliding friction experiments were conducted with 440 C stainless steel balls and hemispherical alumina-yttria stabilized zirconia pins in sliding contact with the MWNTs deposited on quartz disks in air and in vacuum. The results indicate that MWNTs have superior solid lubrication friction properties and endurance lives in air and vacuum under dry conditions. The coefficient of friction of the dispersed MWNTs is close to 0.05 and 0.009 in air and in vacuum, respectively, showing good dry lubricating ability. The wear life of MWNTs exceeds 1 million passes in both air and vacuum showing good durability. In general, the low coefficient of friction can be attributed to the combination of the transferred, agglomerated patches of MWNTs on the counterpart ball or pin surfaces and the presence of tubular MWNTs at interfaces.

  12. Synthesis and characterization of novel low density polyethylene-multiwall carbon nanotube porous composites

    NASA Astrophysics Data System (ADS)

    Rizvi, Reza; Kim, Jae-Kyung; Naguib, Hani

    2009-10-01

    This study details the synthesis and characterization of novel porous composites of low density polyethylene (PE) and multiwalled carbon nanotubes (MWNT). PE-MWNT composites were prepared by melt blending the components in a twin screw compounder and porous structures were produced by a batch technique using CO2 as the solvent. The composites were characterized for dispersion using scanning electron microscopy and transmission electron microscopy; the results indicate a finely dispersed MWNT phase in PE. Thermal, rheological, electrical and mechanical properties of the composites were characterized and results indicate an electrical and rheological percolation threshold concentration of between 1 and 2 wt% MWNT in PE. Substantial improvements in the mechanical and electrical properties of PE were observed with the addition of 5 wt% MWNT. The porous PE-MWNT composites fabricated in this study were found to be conductive and have potential applications as anti-static materials for electrostatic discharge prevention.

  13. Gallium-mediated growth of multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Pan, Zheng Wei; Dai, Sheng; Beach, David B.; Evans, Neal D.; Lowndes, Douglas H.

    2003-03-01

    Liquid gallium was used as a viable and effective solvent and template for high-yield growth of multiwall carbon nanotubes. The gallium-mediated nanotubes thus obtained differ morphologically from nanotubes obtained by using transition metals as catalysts. The nanotubes have a pin-like morphology, generally composed of an oval-shaped tip filled with liquid gallium and a tapered hollow body. The inner diameter of the tube is so large that the inner/outer diameter ratio is usually larger than 0.9. The tubes are naturally opened at both ends. These gallium-filled nanotubes may be used as a nanothermometer in the temperature range of 30 to 550 °C. This study opens an interesting route for carbon nanotube synthesis.

  14. Persistent DNA damage measured by comet assay of Sprague Dawley rat lung cells after five days of inhalation exposure and 1 month post-exposure to dispersed multi-wall carbon nanotubes (MWCNTs) generated by new MWCNT aerosol generation system.

    PubMed

    Kim, Jin Sik; Sung, Jae Huyck; Song, Kyung Seuk; Lee, Ji Hyun; Kim, Sun Man; Lee, Gun Ho; Ahn, Kang Ho; Lee, Jong Seong; Shin, Jae Hoon; Park, Jung Duck; Yu, Il Je

    2012-08-01

    Carbon nanotubes (CNTs) have specific physico-chemical properties that are useful for the electronics, automotive, and construction industries. Yet, despite their many advantages, there is a current lack of available information on the human health and environmental hazards of CNTs. For this reason, the current study investigated the inhalation toxicity potential of multiwall CNTs (MWCNTs). Eight-week-old rats were divided into four groups (10 rats in each group), the fresh-air control (0mg/m(3)), low-concentration group (0.16mg/m(3)), middle-concentration group (0.34mg/m(3)), and high-concentration group (0.94mg/m(3)), and the whole body was exposed to MWCNTs for 5 days (6h/day). Lung cells were then isolated from five rats in each group on day 0 and 1 month after the 5-day exposure, respectively. The MWCNTs were generated by a newly designed generation system, and the MWCNT concentrations in the exposure chambers monitored in accordance with National Institute for Occupational Safety and Health (NIOSH) 0500 using a membrane filter. The MWCNTs were also sampled for an elemental carbon concentration analysis using a glass filter. The animals exhibited no significant body weight changes, abnormal clinical signs, or mortality during the experiment. A single-cell gel electrophoresis assay (Comet assay) was conducted to determine the DNA damage in lung cells obtained from the right lung. As a result, the Olive tail moments were 23.00±1.76, 30.39±1.96, 22.96±1.26, and 33.98±2.21 for the control, low-, middle-, and high-concentration groups, respectively, on day 0 postexposure. Meanwhile, 1 month postexposure, the Olive tail moments were 25.00±2.71, 28.39±3.55, 22.56±1.36, and 31.97±3.16 for the control, low-, middle-, and high-concentration groups, respectively. Thus, the MWCNTs caused a statistically significant increase in lung DNA damage at high concentration (0.94mg/m(3)) when compared with the negative control group on day 0 and 1 month postexposure.

  15. The fabrication and electrochemical properties of electrospun nanofibers of a multiwalled carbon nanotube grafted by chitosan

    NASA Astrophysics Data System (ADS)

    Feng, Wei; Wu, Zigang; Li, Yu; Feng, Yiyu; Yuan, Xiaoyan

    2008-03-01

    Multiwalled carbon nanotubes (MWCNTs) were grafted by chitosan (CS); the product could disperse well in poly(vinyl alcohol) (PVA) aqueous solution with 2% (v/v) acetic acid solution. Because this product has potential in several biological fields, it was electrospun so as to enlarge the surface area. Raman spectra indicated that the electrospinning process did not severely alter the electron hybridization of carbon atoms within the nanotube framework. Moreover and interestingly, these nanofibers showed a novel sheath-core structure; the outer and inner diameters of these sheath-core nanofibers were about 200 nm and 100 nm, respectively. These nanofibers' electrochemical properties were characterized by detection of hydrogen peroxide and voltammetric responses of potassium ferricyanide. The electrospun fibers' web displayed faster electron transfer kinetics and better electrochemical properties than its cast film, which justified further applications in biological areas.

  16. Interactions of 14C-labeled multi-walled carbon nanotubes with soil minerals in water.

    PubMed

    Zhang, Liwen; Petersen, Elijah J; Zhang, Wen; Chen, Yongsheng; Cabrera, Miguel; Huang, Qingguo

    2012-07-01

    Carbon nanotubes are often modified to be stable in the aqueous phase by adding extensive hydrophilic surface functional groups. The stability of such CNTs in water with soil or sediment is one critical factor controlling their environmental fate. We conducted a series of experiments to quantitatively assess the association between water dispersed multi-walled carbon nanotubes (MWCNTs) and three soil minerals (kaolinite, smectite, or shale) in aqueous solution under different sodium concentrations. (14)C-labeling was used in these experiments to unambiguously quantify MWCNTs. The results showed that increasing ionic strength strongly promoted the removal of MWCNTs from aqueous phase. The removal tendency is inversely correlated with the soil minerals' surface potential and directly correlated with their hydrophobicity. This removal can be interpreted by the extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory especially for kaolinite and smectite. Shale, which contains large and insoluble organic materials, sorbed MWCNTs the most strongly. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Construction of photo-driven bioanodes using thylakoid membranes and multi-walled carbon nanotubes.

    PubMed

    Takeuchi, Ryosuke; Suzuki, Arato; Sakai, Kento; Kitazumi, Yuki; Shirai, Osamu; Kano, Kenji

    2018-04-03

    A photo-driven bioanode was constructed using the thylakoid membrane from spinach, carbon nanotubes, and an artificial mediator. By considering a linear free-energy relationship in the electron transfer from the thylakoid membrane to the mediators, and the oxygen resistance of the reduced mediators, 1,2-naphthoquinone was selected as the most suitable mediator for the photo-driven bioanode. Water-dispersed multi-walled carbon nanotubes served as scaffolds to hold the thylakoid membrane on a porous electrode. The constructed photo-driven bioanode exhibited a photocurrent density of over 100μAcm -2 at a photon flux density of 1500μmolm -2 s -1 . Copyright © 2018. Published by Elsevier B.V.

  18. Multiple functionalization of multi-walled carbon nanotubes with carboxyl and amino groups

    NASA Astrophysics Data System (ADS)

    Zhao, Zhiyuan; Yang, Zhanhong; Hu, Youwang; Li, Jianping; Fan, Xinming

    2013-07-01

    In this paper, carboxyl and amino groups have been introduced onto the surface of the multi-walled carbon nanotubes (MWCNTs) by the mixed acid treatment and the diazonium reaction, respectively. The presence of multifunctionality groups on the MWCNTs has been characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric (TGA) analysis, Raman spectra, scanning electron microscopy (SEM) and energy dispersive X-ray spectrum (EDS). The multifunctionalized carbon nanotubes were further utilized to react with acetyl chloride and ethylenediamine (EDA). The formation of the amide bond in the grafting reaction has been confirmed by FT-IR spectroscopy. The result indicates that the further grafting is successful. The multifunctionalized MWCNTs can be a new versatile platform for many interesting applications.

  19. Multiwalled carbon nanotubes in alfalfa and wheat: toxicology and uptake.

    PubMed

    Miralles, Pola; Johnson, Errin; Church, Tamara L; Harris, Andrew T

    2012-12-07

    Data on the bioavailability and toxicity of carbon nanotubes (CNTs) in the environment, and, in particular, on their interactions with vascular plants, are limited. We investigated the effects of industrial-grade multiwalled CNTs (75 wt% CNTs) and their impurities on alfalfa and wheat. Phytotoxicity assays were performed during both seed germination and seedling growth. The germinations of both species were tolerant of up to 2560 mg l(-1) CNTs, and root elongation was enhanced in alfalfa and wheat seedlings exposed to CNTs. Remarkably, catalyst impurities also enhanced root elongation in alfalfa seedlings as well as wheat germination. Thus the impurities, not solely the CNTs, impacted the plants. CNT internalization by plants was investigated using electron microscopy and two-dimensional Raman mapping. The latter showed that CNTs were adsorbed onto the root surfaces of alfalfa and wheat without significant uptake or translocation. Electron microscopy investigations of internalization were inconclusive owing to poor contrast, so Fe(3)O(4)-functionalized CNTs were prepared and studied using energy-filter mapping of Fe(3)O(4). CNTs bearing Fe(3)O(4) nanoparticles were detected in the epidermis of one wheat root tip only, suggesting that internalization was possible but unusual. Thus, alfalfa and wheat tolerated high concentrations of industrial-grade multiwalled CNTs, which adsorbed onto their roots but were rarely taken up.

  20. Multiwalled carbon nanotubes in alfalfa and wheat: toxicology and uptake

    PubMed Central

    Miralles, Pola; Johnson, Errin; Church, Tamara L.; Harris, Andrew T.

    2012-01-01

    Data on the bioavailability and toxicity of carbon nanotubes (CNTs) in the environment, and, in particular, on their interactions with vascular plants, are limited. We investigated the effects of industrial-grade multiwalled CNTs (75 wt% CNTs) and their impurities on alfalfa and wheat. Phytotoxicity assays were performed during both seed germination and seedling growth. The germinations of both species were tolerant of up to 2560 mg l−1 CNTs, and root elongation was enhanced in alfalfa and wheat seedlings exposed to CNTs. Remarkably, catalyst impurities also enhanced root elongation in alfalfa seedlings as well as wheat germination. Thus the impurities, not solely the CNTs, impacted the plants. CNT internalization by plants was investigated using electron microscopy and two-dimensional Raman mapping. The latter showed that CNTs were adsorbed onto the root surfaces of alfalfa and wheat without significant uptake or translocation. Electron microscopy investigations of internalization were inconclusive owing to poor contrast, so Fe3O4-functionalized CNTs were prepared and studied using energy-filter mapping of Fe3O4. CNTs bearing Fe3O4 nanoparticles were detected in the epidermis of one wheat root tip only, suggesting that internalization was possible but unusual. Thus, alfalfa and wheat tolerated high concentrations of industrial-grade multiwalled CNTs, which adsorbed onto their roots but were rarely taken up. PMID:22977097

  1. Multi-Wall Carbon Nanotubes for Flow-Induced Voltage Generation (Preprint)

    DTIC Science & Technology

    2006-08-01

    flow sensors with a large dynamic range. The present work investigates voltage generation properties of multi-walled carbon nanotubes ( MWCNT ) as a...wall carbon nanotubes, has been generated from our perpendicularly-aligned MWCNT in an aqueous solution of 1 M NaCl at a relatively low flow velocity of...generation properties of multi-walled carbon nanotubes ( MWCNT ) as a function of the relative orientation of the nanotube array with respect to the flow

  2. Effects of different processing techniques on multi-walled carbon nanotubes/silicone rubber nanocomposite on tensile strength properties

    NASA Astrophysics Data System (ADS)

    Mazlan, N.; Jaafar, M.; Aziz, A.; Ismail, H.; Busfield, J. J. C.

    2016-10-01

    In this work, two different processing techniques were approached to identify the properties of the multi-walled carbon nanotubes (MWCNT) reinforced polydimethylsiloxane (PDMS). The MWCNT was dispersed in the polymer by using the ultrasonic and twin screw extruder mixer. The final composite showed different manner of dispersed tubes in the silicone rubber matrix. High shear twin screw extruder tends to fragment the tubes during processing compound, which can be observed by scanning electron microscope (SEM). Tensile strength of the extrusion MWCNT/PDMS nanocomposites was found to be higher compared to ultrasonic MWCNT/PDMS nanocomposites.

  3. Carbon nanotube suspensions, dispersions, & composites

    NASA Astrophysics Data System (ADS)

    Simmons, Trevor John

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

  4. He ion irradiation effects on multiwalled carbon nanotubes structure

    NASA Astrophysics Data System (ADS)

    Elsehly, Emad M.; Chechenin, Nikolay G.; Makunin, Alexey V.; Shemukhin, Andrey A.; Motaweh, Hussien A.

    2017-03-01

    Samples of multi-walled carbon nanotubes (MWNTs) were irradiated with 80 keV He ions. Scanning electron microscopy (SEM) inspection showed that the average outer diameters of the tube decreased as a result of ion irradiation. The samples were also characterized using Raman spectrometry by analysis of the intensity of main bands in the spectra of virgin and irradiated MWNT samples. Modifications of the disorder mode (D-band) and the tangential mode (G-band) were studied as a function of irradiation fluences. Raman spectra showed that as the fluence increases, the MWNTs first show disorder due to the produced defects, and then amorphization under still higher fluence of ion irradiation. Thermal and athermal mechanisms of the radiation induced MWNTs modifications are discussed. Contribution to the Topical Issue "Many Particle Spectroscopy of Atoms, Molecules, Clusters and Surfaces", edited by A.N. Grum-Grzhimailo, E.V. Gryzlova, Yu V. Popov, and A.V. Solov'yov.

  5. Freestanding Aligned Multi-walled Carbon Nanotubes for Supercapacitor Devices

    NASA Astrophysics Data System (ADS)

    Moreira, João Vitor Silva; Corat, Evaldo José; May, Paul William; Cardoso, Lays Dias Ribeiro; Lelis, Pedro Almeida; Zanin, Hudson

    2016-11-01

    We report on the synthesis and electrochemical properties of multi-walled carbon nanotubes (MWCNTs) for supercapacitor devices. Freestanding vertically-aligned MWCNTs and MWCNT powder were grown concomitantly in a one-step chemical vapour deposition process. Samples were characterized by scanning and transmission electron microscopies and Fourier transform infrared and Raman spectroscopies. At similar film thicknesses and surface areas, the freestanding MWCNT electrodes showed higher electrochemical capacitance and gravimetric specific energy and power than the randomly-packed nanoparticle-based electrodes. This suggests that more ordered electrode film architectures facilitate faster electron and ion transport during the charge-discharge processes. Energy storage and supply or supercapacitor devices made from these materials could bridge the gap between rechargeable batteries and conventional high-power electrostatic capacitors.

  6. Electric current distribution of a multiwall carbon nanotube

    SciTech Connect

    Chen, Li-Ying; Chang, Chia-Seng, E-mail: jasonc@phys.sinica.edu.tw; Institute of Physics, Academia Sinica, Taipei 11529, Taiwan

    2016-07-15

    The electric current distribution in a multiwall carbon nanotube (MWCNT) was studied by in situ measuring the electric potential along an individual MWCNT in the ultra-high vacuum transmission electron microscope (TEM). The current induced voltage drop along each section of a side-bonded MWCNT was measured by a potentiometric probe in TEM. We have quantitatively derived that the current on the outermost shell depends on the applied current and the shell diameter. More proportion of the total electronic carriers hop into the inner shells when the applied current is increased. The larger a MWCNT’s diameter is, the easier the electronic carriersmore » can hop into the inner shells. We observed that, for an 8 nm MWCNT with 10 μA current applied, 99% of the total current was distributed on the outer two shells.« less

  7. Decoration of multi-walled carbon nanotubes by polymer wrapping and its application in MWCNT/polyethylene composites

    PubMed Central

    2012-01-01

    We dispersed the non-covalent functionalization of multi-walled carbon nanotubes (CNTs) with a polymer dispersant and obtained a powder of polymer-wrapped CNTs. The UV–vis absorption spectrum was used to investigate the optimal weight ratio of the CNTs and polymer dispersant. The powder of polymer-wrapped CNTs had improved the drawbacks of CNTs of being lightweight and difficult to process, and it can re-disperse in a solvent. Then, we blended the polymer-wrapped CNTs and polyethylene (PE) by melt-mixing and produced a conductive masterbatch and CNT/PE composites. The polymer-wrapped CNTs showed lower surface resistivity in composites than the raw CNTs. The scanning electron microscopy images also showed that the polymer-wrapped CNTs can disperse well in composites than the raw CNTs. PMID:22559082

  8. Decoration of multi-walled carbon nanotubes by polymer wrapping and its application in MWCNT/polyethylene composites.

    PubMed

    Hsiao, An-En; Tsai, Shu-Ya; Hsu, Mei-Wen; Chang, Shinn-Jen

    2012-05-06

    We dispersed the non-covalent functionalization of multi-walled carbon nanotubes (CNTs) with a polymer dispersant and obtained a powder of polymer-wrapped CNTs. The UV-vis absorption spectrum was used to investigate the optimal weight ratio of the CNTs and polymer dispersant. The powder of polymer-wrapped CNTs had improved the drawbacks of CNTs of being lightweight and difficult to process, and it can re-disperse in a solvent. Then, we blended the polymer-wrapped CNTs and polyethylene (PE) by melt-mixing and produced a conductive masterbatch and CNT/PE composites. The polymer-wrapped CNTs showed lower surface resistivity in composites than the raw CNTs. The scanning electron microscopy images also showed that the polymer-wrapped CNTs can disperse well in composites than the raw CNTs.

  9. Multiwalled Carbon Nanotubes at the Interface of Pickering Emulsions.

    PubMed

    Briggs, Nicholas M; Weston, Javen S; Li, Brian; Venkataramani, Deepika; Aichele, Clint P; Harwell, Jeffrey H; Crossley, Steven P

    2015-12-08

    Carbon nanotubes exhibit very unique properties in biphasic systems. Their interparticle attraction leads to reduced droplet coalescence rates and corresponding improvements in emulsion stability. Here we use covalent and noncovalent techniques to modify the hydrophilicity of multiwalled carbon nanotubes (MWCNTs) and study their resulting behavior at an oil-water interface. By using both paraffin wax/water and dodecane/water systems, the thickness of the layer of MWNTs at the interface and resulting emulsion stability are shown to vary significantly with the approach used to modify the MWNTs. Increased hydrophilicity of the MWNTs shifts the emulsions from water-in-oil to oil-in-water. The stability of the emulsion is found to correlate with the thickness of nanotubes populating the oil-water interface and relative strength of the carbon nanotube network. The addition of a surfactant decreases the thickness of nanotubes at the interface and enhances the overall interfacial area stabilized at the expense of increased droplet coalescence rates. To the best of our knowledge, this is the first time the interfacial thickness of modified carbon nanotubes has been quantified and correlated to emulsion stability.

  10. Evaluation of multiwalled carbon nanotubes toxicity in two fish species.

    PubMed

    Cimbaluk, Giovani Valentin; Ramsdorf, Wanessa Algarte; Perussolo, Maiara Carolina; Santos, Hayanna Karla Felipe; Da Silva De Assis, Helena Cristina; Schnitzler, Mariane Cristina; Schnitzler, Danielle Caroline; Carneiro, Pedro Gontijo; Cestari, Marta Margarete

    2018-04-15

    Carbon Nanotubes are among the most promising materials for the technology industry. Their unique physical and chemical proprieties may reduce the production costs and improve the efficiency of a large range of products. However, the same characteristics that have made nanomaterials interesting for industry may be responsible for inducing toxic effects on the aquatic organisms. Since the carbon nanotubes toxicity is still a controversial issue, we performed tests of acute and subchronic exposure to a commercial sample of multiwalled carbon nanotubes in two fish species, an exotic model (Danio rerio) and a native one (Astyanax altiparanae). Using the alkaline version of the comet assay on erythrocytes and the piscine micronucleous, also performed on erythrocytes, it was verified that the tested carbon nanotubes sample did not generate apparent genotoxicity by means of single/double DNA strand break or clastogenic/aneugenic effects over any of the species, independently of the exposure period. Although, our findings indicate the possibility of the occurrence of CNTs-DNA crosslinks. Apparently, the sample tested induces oxidative stress after subchronic exposure as shown by activity of superoxide dismutase and catalase. The data obtained by the activity levels of acetylcholinesterase suggests acute neurotoxicity in Astyanax altiparanae and subchronic neurotoxicity in Danio rerio. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Mechanical and Electrical Properties of Organogels with Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Moniruzzaman, Mohammad; Winey, Karen

    2008-03-01

    Organogels are fascinating thermally reversible viscoelastic materials that are comprised of an organic liquid and low concentrations (typically <2 wt %) of low molecular mass organic gelators. We have fabricated the first organogel/carbon nanotube composites using 12-hydroxystearic acid (HSA) as the gelator molecule and pristine and carboxylated multi-wall carbon nanotubes as the nanofillers and 1,2-dichlorobenzene as the organic solvent. We have achieved significant improvements in the mechanical and electrical properties of organogels by incorporating these carbon nanotubes. For example, the linear viscoelastic regime of the HSA organogel, an indicator of the strength of the gel, extends by a factor of 4 with the incorporation of 0.2 wt% of the carboxylated nanotubes. Also, the carbon nanotubes (specially the pristine tubes) improve the electrical conductivity of the organogels, e.g. six orders of magnitude enhancement in electrical conductivity with 0.2 wt% of pristine tubes. Differential scanning calorimetry experiments indicate that the nanotubes do not affect the thermoreversibility of the organogels.

  12. Synthesis of multiwalled carbon nanotube from different grades of carbon black using arc discharge method

    SciTech Connect

    Arora, Neha, E-mail: n4neha31@gmail.com; Sharma, N. N.; Director, School of Automobile, Mechanical & Mechatronics, Manipal University,Jaipur,India

    2016-04-13

    This paper describes the synthesis of nanotube from different grades (Tread * A(non-ASTM), N134,N121,N660 and N330)of carbon black using DC arc discharge method at 40A current for 60sec. Carbon black samples of different grades were procured from industry (Aditya Birla Science and Technology Limited, India). Scanning Electron Micrographs (SEM) of the deposited carbon nanostructures suggests that MWCNTs are formed at 40A and for a minimal exposure time of 60sec.The result formed indicates the N330 grade of carbon black gets converted to MWCNTs (Multiwall Carbon nanotube) as compared to other grades.

  13. Multi-walled carbon nanotubes/polymer composites in absence and presence of acrylic elastomer (ACM).

    PubMed

    Kumar, S; Rath, T; Mahaling, R N; Mukherjee, M; Khatua, B B; Das, C K

    2009-05-01

    Polyetherimide/Multiwall carbon nanotube (MWNTs) nanocomposites containing as-received and modified (COOH-MWNT) carbon nanotubes were prepared through melt process in extruder and then compression molded. Thermal properties of the composites were characterized by thermo-gravimetric analysis (TGA). Field emission scanning electron microscopy (FESEM) images showed that the MWNTs were well dispersed and formed an intimate contact with the polymer matrix without any agglomeration. However the incorporation of modified carbon nanotubes formed fascinating, highly crosslinked, and compact network structure throughout the polymer matrix. This showed the increased adhesion of PEI with modified MWNTs. Scanning electron microscopy (SEM) also showed high degree of dispersion of modified MWNTs along with broken ends. Dynamic mechanical analysis (DMA) results showed a marginal increase in storage modulus (E') and glass transition temperature (T(g)) with the addition of MWNTs. Increase in tensile strength and impact strength of composites confirmed the use the MWNTs as possible reinforcement agent. Both thermal and electrical conductivity of composites increased, but effect is more pronounced on modification due to formation of network of carbon nanotubes. Addition of acrylic elastomer to developed PEI/MWNTs (modified) nanocomposites resulted in the further increase in thermal and electrical properties due to the formation of additional bond between MWNTs and acrylic elastomers at the interface. All the results presented are well corroborated by SEM and FESEM studies.

  14. Thermogravimetric analysis of the interaction of ferromagnetic metal atom and multiwalled carbon nanotubes.

    PubMed

    Rawat, Naveen; Gudyaka, Russel; Kumar, Mohit; Joshi, Bharat; Santhanam, Kalathur S V

    2008-04-01

    This paper describes the thermal oxidative behavior of atomized iron or atomized cobalt in the presence of multiwalled carbon nanotubes (MWCNT). The thermogravimetric analysis shows the atomized iron thermal oxidation starts at about 500 degrees C that is absent when the atomized iron is sintered with multiwalled carbon naonotubes. The thermal oxidation of iron in the sintered samples requires the collapse of the multiwalled carbon nanotubes. A similar behavior is observed with atomized cobalt when its oxidation requires the collapse of the nanotubes. This thermal oxidative shift is interpreted as due to the atomized iron or atomized cobalt atom experiencing extensive overlap and confinement effect with multiwalled carbon nanotubes causing a spin transfer. This confinement effect is suggested to produce a transformation of iron from the outermost electronic distribution of 3d64s2 to an effective configuration of 3d84s0 and for cobalt 3d74s2 to 3d94s0 producing spintronics effect.

  15. Improved electrical conductivity of poly(ethylene oxide) nanofibers using multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lee, J. Y.; Kang, T.-H.; Choi, J. H.; Choi, I.-S.; Yu, W.-R.

    2018-03-01

    Highly conductive nanofibers with 1570 S/m were obtained from an electrospun solution of polymer containing multiwalled carbon nanotubes (MWCNTs). Homogeneous dispersion of high concentrations of MWCNTs was achieved by attaching poly(styrenesulfonic acid graft aniline) (PSS-g-ANI), an amphiphilic surfactant, to the MWCNT surface. The hydrophilic sulfonic acid group facilitated the dissolution of PSS-g-ANI-grafted MWCNTs in a polyethylene oxide (PEO) solution up to 6.7 wt% MWCNT. To our knowledge, this is the highest level of MWCNT doping attained in a solution designed for electrospinning. With the incorporation of PSS-g-ANI, the concentration of MWCNTs embedded in the electrospun nanofibers increased. More importantly, the alignment of MWCNTs along the nanofiber axis increased significantly, as confirmed by observed birefringence under crossed polarizers. The combination of higher doping levels and better alignment afforded highly conductive nanofibers suitable for electronic nanodevices.

  16. Comparison of quasistatic to impact mechanical properties of multiwall carbon nanotube/polycarbonate composites

    SciTech Connect

    Brühwiler, Paul A.; Barbezat, Michel; Necola, Adly

    2010-10-22

    We report the quasistatic tensile and impact penetration properties (falling dart test) of injection-molded polycarbonate samples, as a function of multiwall carbon nanotube (MWNT) concentration (0.0-2.5%). The MWNT were incorporated by dilution of a commercial MWNT/polycarbonate masterbatch. The stiffness and quasistatic yield strength of the composites increased approximately linearly with MWNT concentration in all measurements. The energy absorbed in fracture was, however, a negative function of the MWNT concentration, and exhibited different dependencies in quasistatic and impact tests. Small-angle x-ray scattering (SAXS) showed that the dispersion of the MWNT was similar at all concentrations. The negative effects on energy absorptionmore » are attributed to agglomerates remaining in the samples, which were observed in optical microscopy and SAXS. Overall, there was a good correspondence between static and dynamic energy absorption.« less

  17. The impact of different multi-walled carbon nanotubes on the X-band microwave absorption of their epoxy nanocomposites.

    PubMed

    Che, Bien Dong; Nguyen, Bao Quoc; Nguyen, Le-Thu T; Nguyen, Ha Tran; Nguyen, Viet Quoc; Van Le, Thang; Nguyen, Nieu Huu

    2015-01-01

    Carbon nanotube (CNT) characteristics, besides the processing conditions, can change significantly the microwave absorption behavior of CNT/polymer composites. In this study, we investigated the influence of three commercial multi-walled CNT materials with various diameters and length-to-diameter aspect ratios on the X-band microwave absorption of epoxy nanocomposites with CNT contents from 0.125 to 2 wt%, prepared by two dispersion methods, i.e. in solution with surfactant-aiding and via ball-milling. The laser diffraction particle size and TEM analysis showed that both methods produced good dispersions at the microscopic level of CNTs. Both a high aspect ratio resulting in nanotube alignment trend and good infiltration of the matrix in the individual nanotubes, which was indicated by high Brookfield viscosities at low CNT contents of CNT/epoxy dispersions, are important factors to achieve composites with high microwave absorption characteristics. The multi-walled carbon nanotube (MWCNT) with the largest aspect ratio resulted in composites with the best X-band microwave absorption performance, which is considerably better than that of reported pristine CNT/polymer composites with similar or lower thicknesses and CNT loadings below 4 wt%. A high aspect ratio of CNTs resulting in microscopic alignment trend of nanotubes as well as a good level of micro-scale CNT dispersion resulting from good CNT-matrix interactions are crucial to obtain effective microwave absorption performance. This study demonstrated that effective radar absorbing MWCNT/epoxy nanocomposites having small matching thicknesses of 2-3 mm and very low filler contents of 0.25-0.5 wt%, with microwave energy absorption in the X-band region above 90% and maximum absorption peak values above 97%, could be obtained via simple processing methods, which is promising for mass production in industrial applications. Graphical AbstractComparison of the X-band microwave reflection loss of epoxy composites of

  18. Highly Stable and Flexible Pressure Sensors with Modified Multi-Walled Carbon Nanotube/Polymer Composites for Human Monitoring

    PubMed Central

    He, Yin; Ming, Yue; Li, Wei; Li, Yafang; Wu, Maoqi; Song, Jinzhong; Li, Xiaojiu; Liu, Hao

    2018-01-01

    A facile method for preparing an easy processing, repeatable and flexible pressure sensor was presented via the synthesis of modified multi-walled carbon nanotubes (m-MWNTs) and polyurethane (PU) films. The surface modification of multi-walled carbon nanotubes (MWNTs) simultaneously used a silane coupling agent (KH550) and sodium dodecyl benzene sulfonate (SDBS) to improve the dispersibility and compatibility of the MWNTs in a polymer matrix. The electrical property and piezoresistive behavior of the m-MWNT/PU composites were compared with raw multi-walled carbon nanotube (raw MWNT)/PU composites. Under linear uniaxial pressure, the m-MWNT/PU composite exhibited 4.282%kPa−1 sensitivity within the pressure of 1 kPa. The nonlinear error, hysteresis error and repeatability error of the piezoresistivity of m-MWNT/PU decreased 9%, 16.72% and 54.95% relative to raw MWNT/PU respectively. Therefore, the piezoresistive response of m-MWNT/PU had better stability than that of raw MWNT/PU composites. The m-MWNT/PU sensors could be utilized in wearable devices for body movement detection, monitoring of respiration and pressure detection in garments. PMID:29701643

  19. Highly Stable and Flexible Pressure Sensors with Modified Multi-Walled Carbon Nanotube/Polymer Composites for Human Monitoring.

    PubMed

    He, Yin; Ming, Yue; Li, Wei; Li, Yafang; Wu, Maoqi; Song, Jinzhong; Li, Xiaojiu; Liu, Hao

    2018-04-26

    A facile method for preparing an easy processing, repeatable and flexible pressure sensor was presented via the synthesis of modified multi-walled carbon nanotubes (m-MWNTs) and polyurethane (PU) films. The surface modification of multi-walled carbon nanotubes (MWNTs) simultaneously used a silane coupling agent (KH550) and sodium dodecyl benzene sulfonate (SDBS) to improve the dispersibility and compatibility of the MWNTs in a polymer matrix. The electrical property and piezoresistive behavior of the m-MWNT/PU composites were compared with raw multi-walled carbon nanotube (raw MWNT)/PU composites. Under linear uniaxial pressure, the m-MWNT/PU composite exhibited 4.282%kPa −1 sensitivity within the pressure of 1 kPa. The nonlinear error, hysteresis error and repeatability error of the piezoresistivity of m-MWNT/PU decreased 9%, 16.72% and 54.95% relative to raw MWNT/PU respectively. Therefore, the piezoresistive response of m-MWNT/PU had better stability than that of raw MWNT/PU composites. The m-MWNT/PU sensors could be utilized in wearable devices for body movement detection, monitoring of respiration and pressure detection in garments.

  20. Pre-treatment of multi-walled carbon nanotubes for polyetherimide mixed matrix hollow fiber membranes.

    PubMed

    Goh, P S; Ng, B C; Ismail, A F; Aziz, M; Hayashi, Y

    2012-11-15

    Mixed matrix hollow fibers composed of multi-walled carbon nanotubes (MWCNTs) and polyetherimide (PEI) were fabricated. Pre-treatment of MWCNTs was carried out prior to the incorporation into the polymer matrix using a simple and feasible two stages approach that involved dry air oxidation and surfactant dispersion. The characterizations of the surface treated MWCNTs using TEM and Raman spectroscopy have evidenced the effectiveness of dry air oxidation in eliminating undesired amorphous carbon and metal catalyst while surfactant dispersion using Triton X100 has suppressed the agglomeration of MWCNTs. The resultant mixed matrix hollow fibers were applied for O(2)/N(2) pure gas separation. Interestingly, it was found that removal of disordered amorphous carbons and metal particles has allowed the hollow structures to be more accessible for the fast and smooth transport of gas molecules, hence resulted in noticeable improvement in the gas separation properties. The composite hollow fibers embedded with the surface modified MWCNTs showed increase in permeability as much as 60% while maintaining the selectivity of the O(2)/N(2) gas pair. This study highlights the necessity to establish an appropriate pre-treatment approach for MWCNTs in order to fully utilize the beneficial transport properties of this material in mixed matrix polymer nanocomposite for gas separation. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. Simple introduction of carboxyl head group with alkyl spacer onto multiwalled carbon nanotubes by solution plasma process

    NASA Astrophysics Data System (ADS)

    Nemoto, Shimpei; Ueno, Tomonaga; Watthanaphanit, Anyarat; Hieda, Junko; Bratescu, Maria Antoaneta; Saito, Nagahiro

    2017-09-01

    A simple method of fabricating carboxyl-terminated multiwalled carbon nanotubes (MWCNTs) with alkyl spacers was developed to improve the dispersion quality of MWCNTs in aqueous solutions using solution plasma (SP) in a 6-aminocaproic acid solution. The formation of SP in the solution led to better dispersion of MWCNTs in aqueous solutions. Fourier transform infrared spectroscopy (FT-IR) results indicate that a carboxyl group with an alkyl spacer can be introduced by SP treatment in the 6-aminocaproic acid solution. Sedimentation tests show that the SP-treated MWCNTs in the 6-aminocaproic acid solution retained their good dispersion quality in aqueous solutions of pHs 5, 6, and 9. The alkyl spacer plays an important role in the preservation of dispersion states particularly at pH 6.

  2. Effect of multiwalled carbon nanotubes on UASB microbial consortium.

    PubMed

    Yadav, Tushar; Mungray, Alka A; Mungray, Arvind K

    2016-03-01

    The continuous rise in production and applications of carbon nanotubes (CNTs) has grown a concern about their fate and toxicity in the environment. After use, these nanomaterials pass through sewage and accumulate in wastewater treatment plants. Since, such plants rely on biological degradation of wastes; their activity may decrease due to the presence of CNTs. This study investigated the effect of multiwalled carbon nanotubes (MWCNTs) on upflow anaerobic sludge blanket (UASB) microbial activity. The toxic effect on microbial viability, extracellular polymeric substances (EPS), volatile fatty acids (VFA), and biogas generation was determined. The reduction in a colony-forming unit (CFU) was 29 and 58 % in 1 and 100 mg/L test samples, respectively, as compared to control. The volatile fatty acids and biogas production was also found reduced. The scanning electron microscopy (SEM) and fluorescent microscopy images confirmed that the MWCNT mediated microbial cell damage. This damage caused the increase in EPS carbohydrate, protein, and DNA concentration. Fourier transform infrared (FTIR) spectroscopy results supported the alterations in sludge EPS due to MWCNT. Our observations offer a new insight to understand the nanotoxic effect of MWCNTs on UASB microflora in a complex environment system.

  3. Multiwall carbon nanotubes modulate paraquat toxicity in Arabidopsis thaliana.

    PubMed

    Fan, Xiaoji; Xu, Jiahui; Lavoie, Michel; Peijnenburg, W J G M; Zhu, Youchao; Lu, Tao; Fu, Zhengwei; Zhu, Tingheng; Qian, Haifeng

    2018-02-01

    Carbon nanotubes can be either toxic or beneficial to plant growth and can also modulate toxicity of organic contaminants through surface sorption. The complex interacting toxic effects of carbon nanotubes and organic contaminants in plants have received little attention in the literature to date. In this study, the toxicity of multiwall carbon nanotubes (MWCNT, 50 mg/L) and paraquat (MV, 0.82 mg/L), separately or in combination, were evaluated at the physiological and the proteomic level in Arabidopsis thaliana for 7-14 days. The results revealed that the exposure to MWCNT had no inhibitory effect on the growth of shoots and leaves. Rather, MWCNT stimulated the relative electron transport rate and the effective photochemical quantum yield of PSII value as compared to the control by around 12% and lateral root production up to nearly 4-fold as compared to the control. The protective effect of MWCNT on MV toxicity on the root surface area could be quantitatively explained by the extent of MV adsorption on MWCNT and was related to stimulation of photosynthesis, antioxidant protection and number and area of lateral roots which in turn helped nutrient assimilation. The influence of MWCNT and MV on photosynthesis and oxidative stress at the physiological level was consistent with the proteomics analysis, with various over-expressed photosynthesis-related proteins (by more than 2 folds) and various under-expressed oxidative stress related proteins (by about 2-3 folds). This study brings new insights into the interactive effects of two xenobiotics (MWCNT and MV) on the physiology of a model plant. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Mechanical Properties and Durability of Ultra High Strength Concrete Incorporating Multi-Walled Carbon Nanotubes

    PubMed Central

    Lu, Liulei; Ouyang, Dong; Xu, Weiting

    2016-01-01

    In this work, the effect of the addition of multi-walled carbon nanotubes (MWCNTs) on the mechanical properties and durability of ultra high strength concrete (UHSC) is reported. First, the MWCNTs were dispersed by a nano sand-mill in the presence of a surfactant in water. The UHSC specimens were prepared with various amounts of MWCNTs, ranging from 0% to 0.15% by weight of cement (bwoc). Results indicated that use of an optimal percentage of MWCNTs (0.05% bwoc) caused a 4.63% increase in compressive strength and a 24.0% decrease in chloride diffusion coefficient of UHSC at 28 days curing. Moreover, the addition of MWCNTs also improved the flexural strength and deformation ability. Furthermore, a field-emission scanning electron microscopy (FE-SEM) was used to observe the dispersion of MWCNTs in the cement matrix and morphology of the hardened cement paste containing MWCNTs. FE-SEM observation revealed that MWCNTs were well dispersed in the matrix and no agglomerate was found and the reinforcing effect of MWCNTs on UHSC was thought to be pulling out and microcrack bridging of MWCNTs, which transferred the load in tension. PMID:28773541

  5. Mechanical Properties and Durability of Ultra High Strength Concrete Incorporating Multi-Walled Carbon Nanotubes.

    PubMed

    Lu, Liulei; Ouyang, Dong; Xu, Weiting

    2016-05-27

    In this work, the effect of the addition of multi-walled carbon nanotubes (MWCNTs) on the mechanical properties and durability of ultra high strength concrete (UHSC) is reported. First, the MWCNTs were dispersed by a nano sand-mill in the presence of a surfactant in water. The UHSC specimens were prepared with various amounts of MWCNTs, ranging from 0% to 0.15% by weight of cement (bwoc). Results indicated that use of an optimal percentage of MWCNTs (0.05% bwoc) caused a 4.63% increase in compressive strength and a 24.0% decrease in chloride diffusion coefficient of UHSC at 28 days curing. Moreover, the addition of MWCNTs also improved the flexural strength and deformation ability. Furthermore, a field-emission scanning electron microscopy (FE-SEM) was used to observe the dispersion of MWCNTs in the cement matrix and morphology of the hardened cement paste containing MWCNTs. FE-SEM observation revealed that MWCNTs were well dispersed in the matrix and no agglomerate was found and the reinforcing effect of MWCNTs on UHSC was thought to be pulling out and microcrack bridging of MWCNTs, which transferred the load in tension.

  6. A comparison of LLDPE-based nanocomposites containing multi-walled carbon nanotubes and graphene

    NASA Astrophysics Data System (ADS)

    Vasileiou, Alexandros; Docoslis, Aristides; Kontopoulou, Marianna

    2015-05-01

    Composites of linear-low density polyethylene (LLDPE) with multi-walled carbon nanotubes (MWCNT) and thermally reduced graphene (TRGO) were produced by melt compounding. The composites were compatibilized by grafting aromatic pyridine groups onto the LLDPE backbone. The aromatic moieties established non-covalent π-π interactions with the carbon nanostructures, thus allowing for efficient dispersion, without compromizing their electrical properties. By using identical matrices, it was possible to investigate the effects of filler geometry on the electrical, mechanical and rheological properties of the composites. The 1-D nature and smaller surface area of the MWCNT facilitated their dispersion within the polymer matrix, whereas the graphene agglomerates appeared to breakup through an erosion mechanism. The resulting mixture of aggregates and individual graphene platelets favored lower electrical and rheological percolation thresholds. However the maximum electrical conductivity achieved in the TRGO/LLDPE was lower by about an order of magnitude compared to the MWCNT/LLDPE composites, probably due to residual oxygen in the graphene's structure. TRGO based composites presented higher moduli at the same filler loadings, while elongations at break were comparable. All composites exhibited time-dependent rheological properties, indicative of their tendency to aggregate. A more pronounced increase in viscoelastic properties was noted in the composites containing TRGO, presumably due to the higher surface area of the graphene platelets, and the presence of larger aggregates.

  7. Dielectric, electric and thermal properties of carboxylic functionalized multiwalled carbon nanotubes impregnated polydimethylsiloxane nanocomposite

    NASA Astrophysics Data System (ADS)

    Sagar, Sadia; Iqbal, Nadeem; Maqsood, Asghari

    2013-06-01

    The dielectric, electric and thermal properties of carboxylic functionalized multiwalled carbon nanotubes (F-MWCNT) incorporated into the polydimethylsiloxane (PDMS) were evaluated to determine their potential in the field of electronic materials. Carboxylic functionalization of the pristine multi walled carbon tubes (Ps-MWCNT) was confirmed through Fourier transform infrared spectroscopy, X-ray diffraction patterns for both Ps-MWCNTs and F-MWCNTs elaborated that crystalline behavior did not change with carboxylic moieties. Thermogravimetric and differential thermal analyses were performed to elucidate the thermal stability with increasing weight % addition of F-MWCNTs in the polymer matrix. Crystallization/glass transition / melting temperatures were evaluated using differential scanning calorimeter and it was observed that glass transition and crystallization temperatures were diminished while temperatures of first and second melting transitions were progressed with increasing F-MWCNT concentration in the PDMS matrix. Scanning electron microscopy and energy dispersive x-ray spectroscopy were carried out to confirm the morphology, functionalization, and uniform dispersion of F-MWCNTs in the polymer matrix. Electrical resistivity at temperature range (100-300°C), dielectric loss (tanδ) and dielectric parameters (epsilon/ epsilon//) were measured in the frequency range (1MHz-3GHz). The measured data simulate that the aforementioned properties were influenced by increasing filler contents in the polymer matrix because of the high polarization of conductive F-MWCNTs at the reinforcement/polymer interface.

  8. Ionization Gas Sensor using Aligned Multiwalled Carbon Nanotubes Array

    SciTech Connect

    Kermany, A. R.; Mohamed, N. M.; Singh, B. S. M.

    2011-05-25

    The challenge with current conventional gas sensors which are operating using semiconducting oxides is their size. After the introduction of nanotechnology and in order to reduce the dimension and consequently the power consumption and cost, new materials such as carbon nanotubes (CNTs) are being introduced. From previous works and characterization results, it was proven that the CNTs based gas sensor has better sensitivity, selectivity and faster response time in compared with semiconducting oxides based gas sensors. As in this work, a fabrication and successful testing of an ionization-based gas sensor using aligned Multiwalled CNTs (MWCNTs) as sensing element is discussed,more » in which MWCNTs array and Al film are used as anode and cathode plates respectively with electrode separation ranging from 80 {mu}m to 140 {mu}m. Aligned MWCNTs array was incorporated into a sensor configuration in the gas chamber for testing of gases such as argon, air, and mixed gas of 2%H{sub 2} in air. Obtained results show that among the three gases, argon has the lowest breakdown voltage whilst air has the highest value and the breakdown voltage was found to decrease as the electrode spacing was reduced from 140 {mu}m to 80 {mu}m for all three gases.« less

  9. Mobility of multiwalled carbon nanotubes in porous media.

    PubMed

    Liu, Xueying; O'Carroll, Denis M; Petersen, Elijah J; Huang, Qingguo; Anderson, C Lindsay

    2009-11-01

    Engineered multiwalled carbon nanotubes (MWCNTs) are the subject of intense research and are expected to gain widespread usage in a broad variety of commercial products. However, concerns have been raised regarding potential environmental and human health risks. The mobility of MWCNTs in porous media is examined in this study using one-dimensional flow-through column experiments under conditions representative of subsurface and drinking water treatment systems. Results demonstrate that pore water velocity strongly influenced MWCNT transport, with high MWCNT mobility at pore water velocities greater than 4.0 m/d. A numerical simulator, which incorporated a newly developed theoretical collector efficiency relationship for MWCNTs in spherical porous media, was developed to model observed column results. The model, which incorporated traditional colloid filtration theory in conjunction with a site-blocking term, yielded good agreement with observed results in quartz sand-packed column experiments. Experiments were also conducted in glass bead-packed columns with the same mean grain size as the quartz sand-packed columns. MWCNTs were more mobile in the glass bead-packed columns.

  10. Interface interactions in benzophenone doped by multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lebovka, N. I.; Goncharuk, A.; Melnyk, V. I.; Puchkovska, G. A.

    2009-08-01

    The interface interactions were studied by methods of conductometry, low-temperature phosphorescence and differential scanning calorimetry (DSC) in multiwalled carbon nanotubes (MWCNT) and benzophenone (BP) composite. The concentration of MWCNTs was varied within 0-1 wt%. A percolative threshold was found at MWCNT concentrations exceeding 0.1 wt%. The integration of MWCNTs caused melting temperature increase (≈3 K for 1 wt% of MWCNTs). The effect of positive thermal resistively coefficient, as well as substantial hysteretic behaviour of electrical conductivity σ in a heating-cooling cycle, was observed near the melting point of BP ( T m=321.5 K). The activation-type temperature behaviour of electrical conductivity was observed in the temperature range of supercooled BP. The activation energy was decreasing with increase of MWCNT concentration. The observed nonlinear dependencies of electrical conductivity σ vs. applied voltage U reflect the transport mechanism of the charge carriers through amorphous interface films formed near the surface of the MWCNTs. The thermal shifts of phosphorescence spectra measured within the temperature range 5-200 K evidence existence of such interface films of amorphous BP with width of the order of 0.1 μm.

  11. Microwave conductance properties of aligned multiwall carbon nanotube textile sheets

    SciTech Connect

    Brown, Brian L.; Martinez, Patricia; Zakhidov, Anvar A.

    2015-07-06

    Understanding the conductance properties of multi-walled carbon nanotube (MWNT) textile sheets in the microwave regime is essential for their potential use in high-speed and high-frequency applications. To expand current knowledge, complex high-frequency conductance measurements from 0.01 to 50 GHz and across temperatures from 4.2 K to 300 K and magnetic fields up to 2 T were made on textile sheets of highly aligned MWNTs with strand alignment oriented both parallel and perpendicular to the microwave electric field polarization. Sheets were drawn from 329 and 520 μm high MWNT forests that resulted in different DC resistance anisotropy. For all samples, themore » microwave conductance can be modeled approximately by a shunt capacitance in parallel with a frequency-independent conductance, but with no inductive contribution. Finally, this is consistent with diffusive Drude conduction as the primary transport mechanism up to 50 GHz. Further, it is found that the microwave conductance is essentially independent of both temperature and magnetic field.« less

  12. Electron Beam Irradiation Induced Multiwalled Carbon Nanotubes Fusion inside SEM.

    PubMed

    Shen, Daming; Chen, Donglei; Yang, Zhan; Liu, Huicong; Chen, Tao; Sun, Lining; Fukuda, Toshio

    2017-01-01

    This paper reported a method of multiwalled carbon nanotubes (MWCNTs) fusion inside a scanning electron microscope (SEM). A CNT was picked up by nanorobotics manipulator system which was constructed in SEM with 21 DOFs and 1 nm resolution. The CNT was picked up and placed on two manipulators. The tensile force was 140 nN when the CNT was pulled into two parts. Then, two parts of the CNT were connected to each other by two manipulators. The adhered force between two parts was measured to be about 20 nN. When the two parts of CNT were connected again, the contact area was fused by focused electron beam irradiation for 3 minutes. The tensile force of the junction was measured to be about 100 nN. However, after fusion, the tensile force was five times larger than the tensile force connected only by van der Waals force. This force was 70 percent of the tensile force before pulling out of CNTs. The results revealed that the electron beam irradiation was a promising method for CNT fusion. We hope this technology will be applied to nanoelectronics in the near future.

  13. Determinants of the Thrombogenic Potential of Multiwalled Carbon Nanotubes

    PubMed Central

    Burke, Andrew; Singh, Ravi; Carroll, David L.; Owen, John; Kock, Nancy D.; D’Agostino, Ralph; Torti, Frank M.; Torti, Suzy V.

    2011-01-01

    Multiwalled carbon nanotubes (MWCNTs) are cylindrical tubes of graphitic carbon with unique physical and electrical properties. MWCNTs are being explored for a variety of diagnostic and therapeutic applications. Successful biomedical application of MWCNTs will require compatibility with normal circulatory components, including constituents of the hemostatic cascades. In this manuscript, we compare the thrombotic activity of MWCNTs in vitro and in vivo. We also assess the influence of functionalization of MWCNTs on thrombotic activity. In vitro, MWCNT activate the intrinsic pathway of coagulation as measured by activated partial thromboplastin time (aPTT) assays. Functionalization by amidation or carboxylation enhances this procoagulant activity. Mechanistic studies demonstrate that MWCNTs enhance propagation of the intrinsic pathway via a non-classical mechanism strongly dependent on factor IX. MWCNTs preferentially associate with factor IXa and may provide a platform for its activation. In addition to their effects on the coagulation cascade, MWCNTs activate platelets in vitro, with amidated MWCNTs exhibiting greater platelet activation than carboxylated or pristine MWCNTs. However, contrasting trends are obtained in vivo, where functionalization tends to diminish rather than enhance pro-coagulant activity. Thus, following systemic injection of MWCNTs in mice, pristine MWCNTs decreased platelet counts, increased vWF, and increased D-dimers. In contrast, carboxylated MWCNTS exhibited little procoagulant tendency in vivo, eliciting only a mild and transient decrease in platelets. Amidated MWCNTs elicited no statistically significant change in platelet count. Further, neither carboxylated nor amidated MWCNTs increased vWF or D-dimers in mouse plasma. We conclude that the pro-coagulant tendencies of MWCNTs observed in vitro are not necessarily recapitulated in vivo. Further, functionalization can markedly attenuate the procoagulant activity of MWCNTs in vivo. This

  14. Multi-walled carbon nanotubes: sampling criteria and aerosol characterization

    PubMed Central

    Chen, Bean T.; Schwegler-Berry, Diane; McKinney, Walter; Stone, Samuel; Cumpston, Jared L.; Friend, Sherri; Porter, Dale W.; Castranova, Vincent; Frazer, David G.

    2015-01-01

    This study intends to develop protocols for sampling and characterizing multi-walled carbon nanotube (MWCNT) aerosols in workplaces or during inhalation studies. Manufactured dry powder containing MWCNT’s, combined with soot and metal catalysts, form complex morphologies and diverse shapes. The aerosols, examined in this study, were produced using an acoustical generator. Representative samples were collected from an exposure chamber using filters and a cascade impactor for microscopic and gravimetric analyses. Results from filters showed that a density of 0.008–0.10 particles per µm2 filter surface provided adequate samples for particle counting and sizing. Microscopic counting indicated that MWCNT’s, resuspended at a concentration of 10 mg/m3, contained 2.7 × 104 particles/cm3. Each particle structure contained an average of 18 nanotubes, resulting in a total of 4.9 × 105 nanotubes/cm3. In addition, fibrous particles within the aerosol had a count median length of 3.04 µm and a width of 100.3 nm, while the isometric particles had a count median diameter of 0.90 µm. A combination of impactor and microscopic measurements established that the mass median aerodynamic diameter of the mixture was 1.5 µm. It was also determined that the mean effective density of well-defined isometric particles was between 0.71 and 0.88 g/cm3, and the mean shape factor of individual nanotubes was between 1.94 and 2.71. The information obtained from this study can be used for designing animal inhalation exposure studies and adopted as guidance for sampling and characterizing MWCNT aerosols in workplaces. The measurement scheme should be relevant for any carbon nanotube aerosol. PMID:23033994

  15. Diffusion of multiwall carbon nanotubes (MWCNTs) through a high density polyethylene (HDPE) geomembrane

    PubMed Central

    Saheli, P. T.; Rowe, R. K.; Petersen, E. J.; O’Carroll, D. M.

    2017-01-01

    The new applications for carbon nanotubes (CNTs) in various fields and consequently their greater production volume have increased their potential release to the environment. Landfills are one of the major locations where carbon nanotubes are expected to be disposed and it is important to ensure that they can limit the release of CNTs. Diffusion of multiwall carbon nanotubes (MWCNTs) dispersed in an aqueous media through a high-density polyethylene (HDPE) geomembrane (as a part of the landfill barrier system) was examined. Based on the laboratory tests, the permeation coefficient was estimated to be less than 5.1×10−15 m2/s. The potential performance of a HDPE geomembrane and geosynthetic clay liner (GCL) as parts of a composite liner in containing MWCNTs was modelled for six different scenarios. The results suggest that the low value of permeation coefficient of an HDPE geomembrane makes it an effective diffusive barrier for MWCNTs and by keeping the geomembrane defects to minimum during the construction (e.g., number of holes and length of wrinkles) a composite liner commonly used in municipal solid waste landfills will effectively contain MWCNTs. PMID:28740357

  16. Diffusion of multiwall carbon nanotubes (MWCNTs) through a high density polyethylene (HDPE) geomembrane.

    PubMed

    Saheli, P T; Rowe, R K; Petersen, E J; O'Carroll, D M

    2017-05-01

    The new applications for carbon nanotubes (CNTs) in various fields and consequently their greater production volume have increased their potential release to the environment. Landfills are one of the major locations where carbon nanotubes are expected to be disposed and it is important to ensure that they can limit the release of CNTs. Diffusion of multiwall carbon nanotubes (MWCNTs) dispersed in an aqueous media through a high-density polyethylene (HDPE) geomembrane (as a part of the landfill barrier system) was examined. Based on the laboratory tests, the permeation coefficient was estimated to be less than 5.1×10 -15 m 2 /s. The potential performance of a HDPE geomembrane and geosynthetic clay liner (GCL) as parts of a composite liner in containing MWCNTs was modelled for six different scenarios. The results suggest that the low value of permeation coefficient of an HDPE geomembrane makes it an effective diffusive barrier for MWCNTs and by keeping the geomembrane defects to minimum during the construction (e.g., number of holes and length of wrinkles) a composite liner commonly used in municipal solid waste landfills will effectively contain MWCNTs.

  17. The effects of multi-walled carbon nanotubes on soil microbial community functional and structural diversity

    USDA-ARS?s Scientific Manuscript database

    Applications of nanomaterials, including carbon nanotubes (CNTs), are increasing; however, their impact on the environment is still not well understood. A semi-arid soil was treated with multi-walled carbon nanotubes (MWCNTs) at four different concentrations (10-10000 mgMWCNTs kg-1soil), and incubat...

  18. Functionalized multi-walled carbon nanotubes in an aldol reaction

    NASA Astrophysics Data System (ADS)

    Chronopoulos, D. D.; Kokotos, C. G.; Karousis, N.; Kokotos, G.; Tagmatarchis, N.

    2015-01-01

    The covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with a proline-based derivative is reported. Initially, MWCNTs were oxidized in order to introduce a large number of carboxylic units on their tips followed by N-tert-butoxycarbonyl-2,2'(ethylenedioxy)bis-(ethylamine) conjugation through an amide bond. Then, a proline derivative bearing a carboxylic terminal moiety at the 4-position was coupled furnishing proline-modified MWCNTs. This new hybrid material was fully characterized by spectroscopic and microscopy means and its catalytic activity in the asymmetric aldol reaction between acetone and 4-nitrobenzaldehyde was evaluated for the first time, showing to proceed almost quantitatively in aqueous media. Furthermore, several amino-modified MWCNTs were prepared and examined in the particular aldol reaction. These new hybrid materials exhibited an enhanced catalytic activity in water, contrasting with the pristine MWCNTs as well as the parent organic molecule, which failed to catalyze the reaction efficiently. Furthermore, the modified MWCNTs proved to catalyze the aldol reaction even after three repetitive cycles. Overall, a green approach for the aldol reaction is presented, where water can be employed as the solvent and modified MWCNTs can be used as catalysts, which can be successfully recovered and reused, while their catalytic activity is retained.The covalent functionalization of multi-walled carbon nanotubes (MWCNTs) with a proline-based derivative is reported. Initially, MWCNTs were oxidized in order to introduce a large number of carboxylic units on their tips followed by N-tert-butoxycarbonyl-2,2'(ethylenedioxy)bis-(ethylamine) conjugation through an amide bond. Then, a proline derivative bearing a carboxylic terminal moiety at the 4-position was coupled furnishing proline-modified MWCNTs. This new hybrid material was fully characterized by spectroscopic and microscopy means and its catalytic activity in the asymmetric aldol reaction

  19. Inducing injection barrier by covalent functionalization of multiwall carbon nanotubes acting as Moiré crystals

    NASA Astrophysics Data System (ADS)

    Bonnet, Roméo; Barraud, Clément; Martin, Pascal; Della Rocca, Maria Luisa; Lafarge, Philippe

    2016-10-01

    Covalent functionalization of multiwall carbon nanotubes is a direct method to suppress the conduction of the outermost shell, subject to interactions with the environment. The rehybridized sp3 external shell of the functionalized multiwall carbon nanotubes becomes naturally a hybrid injection barrier allowing the control of the contact resistances and the study of quantum transport in the more protected inner shells. Charge transport measurements performed on isolated multiwall carbon nanotubes of large diameter show an increase of the contact resistance and stabilization in the MΩ range. Electronic quantum properties of the inner shells are highlighted by the observation of superlattice structures in the conductance, recently attributed to the formation of a one-dimensional Moiré pattern.

  20. Mass-produced multi-walled carbon nanotubes as catalyst supports for direct methanol fuel cells.

    PubMed

    Jang, In Young; Park, Ki Chul; Jung, Yong Chae; Lee, Sun Hyung; Song, Sung Moo; Muramatsu, Hiroyuki; Kim, Yong Jung; Endo, Morinobu

    2011-01-01

    Commercially mass-produced multi-walled carbon nanotubes, i.e., VGNF (Showa Denko Co.), were applied to support materials for platinum-ruthenium (PtRu) nanoparticles as anode catalysts for direct methanol fuel cells. The original VGNFs are composed of high-crystalline graphitic shells, which hinder the favorable surface deposition of the PtRu nanoparticles that are formed via borohydride reduction. The chemical treatment of VGNFs with potassium hydroxide (KOH), however, enables highly dispersed and dense deposition of PtRu nanoparticles on the VGNF surface. This capability becomes more remarkable depending on the KOH amount. The electrochemical evaluation of the PtRu-deposited VGNF catalysts showed enhanced active surface areas and methanol oxidation, due to the high dispersion and dense deposition of the PtRu nanoparticles. The improvement of the surface deposition states of the PtRu nanoparticles was significantly due to the high surface area and mesorporous surface structure of the KOH-activated VGNFs.

  1. Hybrid Composite Using Natural Filler and Multi-Walled Carbon Nanotubes (MWCNTs)

    NASA Astrophysics Data System (ADS)

    Nabinejad, Omid; Sujan, D.; Rahman, Muhammad Ekhlasur; Liew, Willey Yun Hsien; Davies, Ian J.

    2017-12-01

    This paper presents an experimental study on the development of hybrid composites comprising of multi-walled carbon nanotubes (MWCNTs) and natural filler (oil palm shell (OPS) powder) within unsaturated polyester (UP) matrix. The results revealed that the dispersion of pristine MWCNTs in the polymer matrix was strongly enhanced through use of the solvent mixing method assisted by ultrasonication. Four different solvents were investigated, namely, ethanol, methanol, styrene and acetone. The best compatibility with minimum side effects on the curing of the polyester resin was exhibited by the styrene solvent and this produced the maximum tensile and flexural properties of the resulting nanocomposites. A relatively small amount of pristine MWCNTs well dispersed within the natural filler polyester composite was found to be capable of improving mechanical properties of hybrid composite. However, increasing the MWCNT amount resulted in increased void content within the matrix due to an associated rapid increase in viscosity of the mixture during processing. Due to this phenomenon, the maximum tensile and flexural strengths of the hybrid composites were achieved at MWCNT contents of 0.2 to 0.4 phr and then declined for higher MWCNT amounts. The flexural modulus also experienced its peak at 0.4 phr MWCNT content whereas the tensile modulus exhibited a general decrease with increasing MWCNT content. Thermal stability analysis using TGA under an oxidative atmosphere showed that adding MWCNTs shifted the endset degradation temperature of the hybrid composite to a higher temperature.

  2. Magnesia tuned multi-walled carbon nanotubes–reinforced alumina nanocomposites

    SciTech Connect

    Ahmad, Iftikhar, E-mail: ifahmad@ksu.edu.sa; Islam, Mohammad; Dar, Mushtaq Ahmad

    2015-01-15

    Magnesia tuned alumina ceramic nanocomposites, reinforced with multi-walled carbon nanotubes, were condensed using pressureless and hot-press sintering processes. Densification, microstructure and mechanical properties of the produced nanocomposites were meticulously investigated. Electron microscopy studies revealed the homogenous carbon nanotube dispersion within the alumina matrix and confirmed the retention of carbon nanotubes' distinctive tubular morphology and nanoscale features during the extreme mixing/sintering processes. Pressureless sintered nanocomposites showed meagre mechanical responses due to the poorly-integrated microstructures with a slight improvement upon magnesia addition. Conversely, both the magnesia addition and application of hot-press sintering technique resulted in the nanocomposite formation with near-theoretical densities (~more » 99%), well-integrated microstructures and superior mechanical properties. Hot-press sintered nanocomposites incorporating 300 and 600 ppm magnesia exhibited an increase in hardness (10 and 11%), flexural strength (5 and 10%) and fracture toughness (15 and 20%) with respect to similar magnesia-free samples. Compared to monolithic alumina, a decent rise in fracture toughness (37%), flexural strength (22%) and hardness (20%) was observed in the hot-press sintered nanocomposites tuned with merely 600 ppm magnesia. Mechanically superior hot-press sintered magnesia tailored nanocomposites are attractive for several load-bearing structural applications. - Highlights: • MgO tailored Al{sub 2}O{sub 3}–2 wt.% CNT nanocomposites are presented. • The role of MgO and sintering on nanocomposite structures and properties was studied. • Well-dispersed CNTs maintained their morphology/structure after harsh sintering. • Hot-pressing and MgO led nanocomposites to higher properties/unified structures. • MgO tuned composites showed higher toughness (37%) and strength (22%) than Al{sub 2}O{sub 3}.« less

  3. Graphene versus Multi-Walled Carbon Nanotubes for Electrochemical Glucose Biosensing

    PubMed Central

    Zheng, Dan; Vashist, Sandeep Kumar; Dykas, Michal Marcin; Saha, Surajit; Al-Rubeaan, Khalid; Lam, Edmond; Luong, John H.T.; Sheu, Fwu-Shan

    2013-01-01

    A simple procedure was developed for the fabrication of electrochemical glucose biosensors using glucose oxidase (GOx), with graphene or multi-walled carbon nanotubes (MWCNTs). Graphene and MWCNTs were dispersed in 0.25% 3-aminopropyltriethoxysilane (APTES) and drop cast on 1% KOH-pre-treated glassy carbon electrodes (GCEs). The EDC (1-ethyl-(3-dimethylaminopropyl) carbodiimide)-activated GOx was then bound covalently on the graphene- or MWCNT-modified GCE. Both the graphene- and MWCNT-based biosensors detected the entire pathophysiological range of blood glucose in humans, 1.4–27.9 mM. However, the direct electron transfer (DET) between GOx and the modified GCE’s surface was only observed for the MWCNT-based biosensor. The MWCNT-based glucose biosensor also provided over a four-fold higher current signal than its graphene counterpart. Several interfering substances, including drug metabolites, provoked negligible interference at pathological levels for both the MWCNT- and graphene-based biosensors. However, the former was more prone to interfering substances and drug metabolites at extremely pathological concentrations than its graphene counterpart. PMID:28809354

  4. Graphene versus Multi-Walled Carbon Nanotubes for Electrochemical Glucose Biosensing.

    PubMed

    Zheng, Dan; Vashist, Sandeep Kumar; Dykas, Michal Marcin; Saha, Surajit; Al-Rubeaan, Khalid; Lam, Edmond; Luong, John H T; Sheu, Fwu-Shan

    2013-03-14

    : A simple procedure was developed for the fabrication of electrochemical glucose biosensors using glucose oxidase (GOx), with graphene or multi-walled carbon nanotubes (MWCNTs). Graphene and MWCNTs were dispersed in 0.25% 3-aminopropyltriethoxysilane (APTES) and drop cast on 1% KOH-pre-treated glassy carbon electrodes (GCEs). The EDC (1-ethyl-(3-dimethylaminopropyl) carbodiimide)-activated GOx was then bound covalently on the graphene- or MWCNT-modified GCE. Both the graphene- and MWCNT-based biosensors detected the entire pathophysiological range of blood glucose in humans, 1.4-27.9 mM. However, the direct electron transfer (DET) between GOx and the modified GCE's surface was only observed for the MWCNT-based biosensor. The MWCNT-based glucose biosensor also provided over a four-fold higher current signal than its graphene counterpart. Several interfering substances, including drug metabolites, provoked negligible interference at pathological levels for both the MWCNT- and graphene-based biosensors. However, the former was more prone to interfering substances and drug metabolites at extremely pathological concentrations than its graphene counterpart.

  5. Plasma-modified graphene nanoplatelets and multiwalled carbon nanotubes as fillers for advanced rubber composites

    NASA Astrophysics Data System (ADS)

    Sicinski, M.; Gozdek, T.; Bielinski, D. M.; Szymanowski, H.; Kleczewska, J.; Piatkowska, A.

    2015-07-01

    In modern rubber industry, there still is a room for new fillers, which can improve the mechanical properties of the composites, or introduce a new function to the material. Modern fillers like carbon nanotubes or graphene nanoplatelets (GnP), are increasingly applied in advanced polymer composites technology. However, it might be hard to obtain a well dispersed system for such systems. The polymer matrix often exhibits higher surface free energy (SFE) level with the filler, which can cause problems with polymer-filler interphase adhesion. Filler particles are not wet properly by the polymer, and thus are easier to agglomerate. As a consequence, improvement in the mechanical properties is lower than expected. In this work, multi-walled carbon nanotubes (MWCNT) and GnP surface were modified with low-temperature plasma. Attempts were made to graft some functionalizing species on plasma-activated filler surface. The analysis of virgin and modified fillers’ SFE was carried out. MWCNT and GnP rubber composites were produced, and ultimately, their morphology and mechanical properties were studied.

  6. 3D printing nano conductive multi-walled carbon nanotube scaffolds for nerve regeneration

    NASA Astrophysics Data System (ADS)

    Lee, Se-Jun; Zhu, Wei; Nowicki, Margaret; Lee, Grace; Nyoung Heo, Dong; Kim, Junghoon; Zuo, Yi Y.; Zhang, Lijie Grace

    2018-02-01

    Objective. Nanomaterials, such as carbon nanotubes (CNTs), have been introduced to modify the surface properties of scaffolds, thus enhancing the interaction between the neural cells and biomaterials. In addition to superior electrical conductivity, CNTs can provide nanoscale structures similar to those present in the natural neural environment. The primary objective of this study is to investigate the proliferative capability and differential potential of neural stem cells (NSCs) seeded on a CNT incorporated scaffold. Approach. Amine functionalized multi-walled carbon nanotubes (MWCNTs) were incorporated with a PEGDA polymer to provide enhanced electrical properties as well as nanofeatures on the surface of the scaffold. A stereolithography 3D printer was employed to fabricate a well-dispersed MWCNT-hydrogel composite neural scaffold with a tunable porous structure. 3D printing allows easy fabrication of complex 3D scaffolds with extremely intricate microarchitectures and controlled porosity. Main results. Our results showed that MWCNT-incorporated scaffolds promoted neural stem cell proliferation and early neuronal differentiation when compared to those scaffolds without the MWCNTs. Furthermore, biphasic pulse stimulation with 500 µA current promoted neuronal maturity quantified through protein expression analysis by quantitative polymerase chain reaction. Significance. Results of this study demonstrated that an electroconductive MWCNT scaffold, coupled with electrical stimulation, may have a synergistic effect on promoting neurite outgrowth for therapeutic application in nerve regeneration.

  7. Determination of multi-walled carbon nanotube bioaccumulation in earthworms measured by a microwave-based detection technique

    EPA Science Inventory

    Reliable quantification techniques for carbon nanotubes (CNTs) are limited. In this study, a new procedure was developed for quantifying multi-walled carbon nanotubes (MWNTs) in earthworms (Eisenia fetida) based on freeze drying and microwave-induced heating. Specifically, earthw...

  8. Dispersions of Carbon nanotubes in Polymer Matrices

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  9. Structure of junctions of multiwalled carbon nanotubes with tetragonal cross section and flattened nanotubes revealed by electron-beam tomography

    NASA Astrophysics Data System (ADS)

    Nagano, Yuta; Kohno, Hideo

    2017-11-01

    Multiwalled carbon nanotubes with tetragonal cross section frequently form junctions with flattened multi-walled carbon nanotubes, a kind of carbon nanoribbon. The three-dimensional structure of the junctions is revealed by transmission-electron-microscopy-based tomography. Two types of junction, parallel and diagonal, are found. The formation mechanism of these two types of junction is discussed in terms of the origami mechanism that was previously proposed to explain the formation of carbon nanoribbons and nanotetrahedra.

  10. Hydrophilic Modification of Multi-Walled Carbon Nanotube for Building Photonic Crystals with Enhanced Color Visibility and Mechanical Strength.

    PubMed

    Li, Feihu; Tang, Bingtao; Xiu, Jinghai; Zhang, Shufen

    2016-04-28

    Low color visibility and poor mechanical strength of polystyrene (PS) photonic crystal films have been the main shortcomings for the potential applications in paints or displays. This paper presents a simple method to fabricate PS/MWCNTs (multi-walled carbon nanotubes) composite photonic crystal films with enhanced color visibility and mechanical strength. First, MWCNTs was modified through radical addition reaction by aniline 2,5-double sulfonic acid diazonium salt to generate hydrophilic surface and good water dispersity. Then the MWCNTs dispersion was blended with PS emulsion to form homogeneous PS/MWCNTs emulsion mixtures and fabricate composite films through thermal-assisted method. The obtained films exhibit high color visibility under natural light and improved mechanical strength owing to the light-adsorption property and crosslinking effect of MWCNTs. The utilization of MWCNTs in improving the properties of photonic crystals is significant for various applications, such as in paints and displays.

  11. Influence of Multi-Walled Carbon Nanotubes on the Thermal and Mechanical Behavior of Carbon/Epoxy Composites (Preprint)

    DTIC Science & Technology

    2007-03-01

    Stephenson Chemical Company, Inc. Carbon Nanotechnologies , Inc. 3 produced the multi-walled carbon nanotubes used in this study. The tube diameters range...5125-5132. 11. Kim S. , Pechar T. W. and Marand E., Desalination , 192(2006): 330-339 12. Cai H., Yan F. Y., and Xue Q. J., Materials Science and

  12. Dispersion stability in carbon nanotube modified polymers and its effect on the fracture toughness

    NASA Astrophysics Data System (ADS)

    Mirjalili, Vahid; Yourdkhani, Mostafa; Hubert, Pascal

    2012-08-01

    In this paper, the dispersion stability of multiwall carbon nanotubes (MWNTs) mixed with an epoxy resin is studied. An instrumented optical microscope with a hot stage was used to study the evolution of the carbon nanotubes (CNTs) dispersion during the cure of the resin. A new image processing approach is then introduced to quantify dispersion and identify the source of dispersion degradation during the cure. The results showed that the reduction of the resin viscosity at temperatures greater than 100 °C caused an irreversible re-agglomeration of the CNTs in the matrix. It was shown that the fine-tuning of the ratio and type of curing agent as well as the curing temperature directly affect the dispersion stability of MWNTs in the epoxy polymer. The dispersion quality was then directly correlated to the fracture toughness of the modified resin and a maximum of 20% improvement was achieved.

  13. Limited transport of functionalized multi-walled carbon nanotubes in two natural soils

    USDA-ARS?s Scientific Manuscript database

    Column experiments were conducted in undisturbed and in repacked soil columns at water contents close to saturation (85–96%) to investigate the transport and retention of functionalized 14C-labeled multi-walled carbon nanotubes (MWCNT) in two natural soils. Additionally, a field lysimeter experiment...

  14. 40 CFR 721.10275 - Multi-walled carbon nanotubes (generic) (P-09-0417).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10275 Multi-walled carbon nanotubes (generic) (P-09-0417). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically...

  15. 40 CFR 721.10276 - Multi-walled carbon nanotubes (generic) (P-10-39).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10276 Multi-walled carbon nanotubes (generic) (P-10-39). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically...

  16. 40 CFR 721.10274 - Multi-walled carbon nanotubes (generic) (P-09-188).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10274 Multi-walled carbon nanotubes (generic) (P-09-188). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically...

  17. 40 CFR 721.10274 - Multi-walled carbon nanotubes (generic) (P-09-188).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10274 Multi-walled carbon nanotubes (generic) (P-09-188). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically...

  18. 40 CFR 721.10279 - Multi-walled carbon nanotubes (generic) (P-10-246).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10279 Multi-walled carbon nanotubes (generic) (P-10-246). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically...

  19. 40 CFR 721.10703 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10703 Multi-walled carbon nanotubes (generic). (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substances identified generically as...

  20. 40 CFR 721.10275 - Multi-walled carbon nanotubes (generic) (P-09-0417).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10275 Multi-walled carbon nanotubes (generic) (P-09-0417). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically...

  1. 40 CFR 721.10671 - Multi-walled carbon nanotubes (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10671 Multi-walled carbon nanotubes (generic). (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substances identified generically as...

  2. 40 CFR 721.10276 - Multi-walled carbon nanotubes (generic) (P-10-39).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10276 Multi-walled carbon nanotubes (generic) (P-10-39). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically...

  3. Fast preparation of hydroxyapatite/superhydrophilic vertically aligned multiwalled carbon nanotube composites for bioactive application.

    PubMed

    Lobo, Anderson O; Corat, Marcus A F; Ramos, Sandra C; Matsushima, Jorge T; Granato, Alessandro E C; Pacheco-Soares, Cristina; Corat, Evaldo J

    2010-12-07

    A method for the electrodeposition of hydroxyapatite films on superhydrophilic vertically aligned multiwalled carbon nanotubes is presented. The formation of a thin homogeneous film with high crystallinity was observed without any thermal treatment and with bioactivity properties that accelerate the in vitro biomineralization process and osteoblast adhesion.

  4. A Multi-Walled Carbon Nanotube-based Biosensor for Monitoring Microcystin-LR in Sources of Drinking Water Supplies

    EPA Science Inventory

    A multi-walled carbon nanotube-based electrochemical biosensor is developed for monitoring microcystin-LR (MC-LR), a toxic cyanobacterial toxin, in sources of drinking water supplies. The biosensor electrodes are fabricated using dense, mm-long multi-walled CNT (MWCNT) arrays gro...

  5. A Novel of Multi-wall Carbon Nanotubes/Chitosan Electrochemical Sensor for Determination of Cupric ion

    NASA Astrophysics Data System (ADS)

    Tan, Funeng; Li, Lei

    2018-03-01

    A multi-wall carbon nanotubes/Chitosan electrochemical sensor had been fabricated by dropping CHS/MWNT solution directly onto the GC surface. The sensor was charactered by cyclic voltammetry and AC impedance with K3Fe(CN)6 as a electrochemical probe; Cyclic voltammograms(CV) and electrochemical impedance spectroscopy(EIS) indicated that the active area and electrochemical behavior of the sensor increased and improved significantly after the electrode was modified by carbon nanotubes dispersed by the chitosan. The sensor showed good electrocatalytic activity of K3Fe(CN)6. Also, from the cyclic voltammograms, we can see the process was diffusion controlled on the bare electrode and kinetics and diffusion controlled on the modified electrode. Finally Cu2+ responsed sensitively at the sensor which supplied a new method for the detection of Cu2+.

  6. Optical transmission of nematic liquid crystal 5CB doped by single-walled and multi-walled carbon nanotubes.

    PubMed

    Lisetski, L N; Fedoryako, A P; Samoilov, A N; Minenko, S S; Soskin, M S; Lebovka, N I

    2014-08-01

    Comparative studies of optical transmission of single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs), dispersed in nematic liquid crystal matrix 5CB, were carried out. The data evidence violations of Beer-Lambert-Bouguer (BLB) law both in cell thickness and concentration dependencies. The most striking is the fact that optical transmission dependencies for SWCNTs and MWCNTs were quite different in the nematic phase, but they were practically indistinguishable in the isotropic phase. Monte Carlo simulations of the impact of aggregation on direct transmission and violation of BLB law were also done. The results were discussed accounting for the tortuous shape of CNTs, their physical properties and aggregation, as well as strong impact of perturbations of the nematic 5CB structure inside coils and in the vicinity of CNT aggregates.

  7. Dispersion of carbon nanotubes in vinyl ester polymer composites

    NASA Astrophysics Data System (ADS)

    Pena-Paras, Laura

    This work focused on a parametric study of dispersions of different types of carbon nanotubes in a polymer resin. Single-walled (SWNTs), double-walled (DWNTs), multi-walled (MWNTs) and XD-grade carbon nanotubes (XD-CNTs) were dispersed in vinyl ester (VE) using an ultra-sonic probe at a fixed frequency. The power, amplitude, and mixing time parameters of sonication were correlated to the electrical and mechanical properties of the composite materials in order to optimize dispersion. The quality of dispersion was quantified by Raman spectroscopy and verified through optical and scanning electron microscopy. By Raman, the CNT distribution, unroping, and damage was monitored and correlated with the composite properties for dispersion optimization. Increasing the ultrasonication energy was found to improve the distribution of all CNT materials and to decrease the size of nanotube ropes, enhancing the electrical conductivity and storage modulus. However, excessive amounts of energy were found to damage CNTs, which negatively affected the properties of the composite. Based on these results the optimum dispersion energy inputs were determined for the different composite materials. The electrical resistivity was lowered by as much as 14, 13, 13, and 11 orders of magnitude for SWNT/VE, DWNT/VE, MWNT/VE, and XD-CNT/VE respectively, compared to the neat resin. The storage modulus was also increased compared to the neat resin by 77%, 82%, 45%, 40% and 85% in SWNT, SAP-f-SWNT, DWNT, MWNT and XD-CNT/VE composites, respectively. This study provides a detailed understanding of how the properties of, nanocomposites are determined by the composite mixing parameters and the distribution, concentration, shape and size of the CNTs. Importantly, it indicates the importance of the need for dispersion metrics to correlate and understand these properties.

  8. Flexible and Transparent Strain Sensors with Embedded Multiwalled Carbon Nanotubes Meshes.

    PubMed

    Nie, Bangbang; Li, Xiangming; Shao, Jinyou; Li, Xin; Tian, Hongmiao; Wang, Duorui; Zhang, Qiang; Lu, Bingheng

    2017-11-22

    Strain sensors combining high sensitivity with good transparency and flexibility would be of great usefulness in smart wearable/flexible electronics. However, the fabrication of such strain sensors is still challenging. In this study, new strain sensors with embedded multiwalled carbon nanotubes (MWCNTs) meshes in polydimethylsiloxane (PDMS) films were designed and tested. The strain sensors showed elevated optical transparency of up to 87% and high sensitivity with a gauge factor of 1140 at a small strain of 8.75%. The gauge factors of the sensors were also found relatively stable since they did not obviously change after 2000 stretching/releasing cycles. The sensors were tested to detect motion in the human body, such as wrist bending, eye blinking, mouth phonation, and pulse, and the results were shown to be satisfactory. Furthermore, the fabrication of the strain sensor consisting of mechanically blading MWCNTs aqueous dispersions into microtrenches of prestructured PDMS films was straightforward, was low cost, and resulted in high yield. All these features testify to the great potential of these sensors in future real applications.

  9. Effects of multiwall carbon nanotubes on viscoelastic properties of magnetorheological elastomers

    NASA Astrophysics Data System (ADS)

    Aziz, Siti Aishah Abdul; Amri Mazlan, Saiful; Intan Nik Ismail, Nik; Ubaidillah, U.; Choi, Seung-Bok; Khairi, Muntaz Hana Ahmad; Azhani Yunus, Nurul

    2016-07-01

    The effect of different types of multiwall carbon nanotubes (MWCNTs) on the morphological, magnetic and viscoelastic properties of magnetorheological elastomers (MREs) are studied in this work. A series of natural rubber MRE are prepared by adding MWCNTs as a new additive in MRE. Effects of functionalized MWCNT namely carboxylated MWCNT (COOH-MWCNT) and hydroxylated MWCNT (OH-MWCNT) on the rheological properties of MREs are investigated and the pristine MWCNTs is referred as a control. Epoxidised palm oil (EPO) is used as a medium to disperse carbonyl iron particle (CIP) and sonicate the MWCNTs. Morphological and magnetic properties of MREs are characterized by field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM), respectively. Rheological properties under different magnetic field are evaluated by using parallel plate rheometer. From the results obtained, FESEM images indicate that COOH-MWCNT and CIP have better compatibility which leads to the formation of interconnected network in the matrix. In addition, by adding functionalized COOH-MWCNT, it is shown that the saturation magnetization is 5% higher than the pristine MWCNTs. It is also found that with the addition of COOH-MWCNT, the magnetic properties are improved parallel with enhancement of MR effect particularly at low strain amplitude. It is finally shown that the use of EPO also can contribute to the enhancement of MR performance.

  10. KOH-activated multi-walled carbon nanotubes as platinum supports for oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    He, Chaoxiong; Song, Shuqin; Liu, Jinchao; Maragou, Vasiliki; Tsiakaras, Panagiotis

    In the present investigation, multi-walled carbon nanotubes (MWCNTs) thermally treated by KOH were adopted as the platinum supporting material for the oxygen reduction reaction electrocatalysts. FTIR and Raman spectra were used to investigate the surface state of MWCNTs treated by KOH at different temperatures (700, 800, and 900 °C) and showed MWCNTs can be successfully functionalized. The structural properties of KOH-activated MWCNTs supported Pt were determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and their electrochemical performance was evaluated by the aid of cyclic voltammetry (CV) and rotating disk electrode (RDE) voltammetry. According to the experimental findings of the present work, the surrface of MWCNTs can be successfully functionalized with oxygen-containing groups after activation by KOH, favoring the good dispersion of Pt nanoparticles with narrow size distribution. The as-prepared Pt catalysts supported on KOH treated MWCNTs at higher temperature, possess higher electrochemical surface area and exhibit desirable activity towards oxygen reduction reaction (ORR). More precisely, it has been found that the electrochemical active area of Pt/MWCNTs-900 is approximately two times higher than that of Pt/MWCNTs. It can be concluded that KOH activation is an effective way to decorate MWCNTs' surface with oxygen-containing groups and bigger surface area, which makes them more suitable as electrocatalyst support materials.

  11. Oxidation behavior of multiwall carbon nanotubes with different diameters and morphology

    NASA Astrophysics Data System (ADS)

    Mazov, Ilya; Kuznetsov, Vladimir L.; Simonova, Irina A.; Stadnichenko, Andrey I.; Ishchenko, Arkady V.; Romanenko, Anatoly I.; Tkachev, Evgeniy N.; Anikeeva, Olga B.

    2012-06-01

    Multiwall carbon nanotubes (MWNT) with three medium diameters (20-22, 9-13, and 6-8 nm) and different morphology were chemically oxidized using concentrated nitric acid, mixture of nitric and sulfuric acids ("mélange" solution) and mixture of sulfuric acid and hydrogen peroxide ("piranha" solution). Influence of MWNT type and structure as well as type of oxidizer on the surface composition and structure of nanotubes after oxidation was investigated. Acid-base titration, X-ray photoelectron spectroscopy and thermal gravimetric analysis were used for quantitative and qualitative investigation of surface group composition of initial and oxidized nanotubes. Amount of oxygen-containing groups on the surface of oxidized MWNT depends on the type of initial MWNT. It was found that ratio of different oxygen containing groups is less dependent on the type of oxidizer. Electrophysical properties of initial and oxidized nanotubes were investigated in temperature range 4-293 K and main types of electrical conductivity were determined. It was shown that oxidation results in decrease in electrical conductivity of all samples with simultaneous change in the conductivity mechanism. Dispersive behavior of initial and oxidized nanotubes in different commonly used solvents was investigated. It was shown that oxidation leads to the improvement of sedimentation stability of MWNT in polar solvents.

  12. Antibacterial activity and cytotoxicity of multi-walled carbon nanotubes decorated with silver nanoparticles

    PubMed Central

    Seo, Youngmin; Hwang, Jangsun; Kim, Jieun; Jeong, Yoon; Hwang, Mintai P; Choi, Jonghoon

    2014-01-01

    Recently, various nanoscale materials, including silver (Ag) nanoparticles, have been actively studied for their capacity to effectively prevent bacterial growth. A critical challenge is to enhance the antibacterial properties of nanomaterials while maintaining their biocompatibility. The conjugation of multiple nanomaterials with different dimensions, such as spherical nanoparticles and high-aspect-ratio nanotubes, may increase the target-specific antibacterial capacity of the consequent nanostructure while retaining an optimal biocompatibility. In this study, multi-walled carbon nanotubes (MWCNTs) were treated with a mixture of acids and decorated with Ag nanoparticles via a chemical reduction of Ag cations by ethanol solution. The synthesized Ag-MWCNT complexes were characterized by transmission electron microscopy, X-ray diffractometry, and energy-dispersive X-ray spectroscopy. The antibacterial function of Ag-MWCNTs was evaluated against Methylobacterium spp. and Sphingomonas spp. In addition, the biocompatibility of Ag-MWCNTs was evaluated using both mouse liver hepatocytes (AML 12) and human peripheral blood mononuclear cells. Finally, we determined the minimum amount of Ag-MWCNTs required for a biocompatible yet effective antibacterial treatment modality. We report that 30 μg/mL of Ag-MWCNTs confers antibacterial functionality while maintaining minimal cytotoxicity toward both human and animal cells. The results reported herein would be beneficial for researchers interested in the efficient preparation of hybrid nanostructures and in determining the minimum amount of Ag-MWCNTs necessary to effectively hinder the growth of bacteria. PMID:25336943

  13. Characterization of Multiwalled Carbon Nanotube-Reinforced Hydroxyapatite Composites Consolidated by Spark Plasma Sintering

    PubMed Central

    Kim, Duk-Yeon; Han, Young-Hwan; Lee, Jun Hee; Kang, Inn-Kyu; Jang, Byung-Koog; Kim, Sukyoung

    2014-01-01

    Pure HA and 1, 3, 5, and 10 vol% multiwalled carbon nanotube- (MWNT-) reinforced hydroxyapatite (HA) were consolidated using a spark plasma sintering (SPS) technique. The relative density of pure HA increased with increasing sintering temperature, but that of the MWNT/HA composite reached almost full density at 900°C, and then decreased with further increases in sintering temperature. The relative density of the MWNT/HA composites increased with increasing MWNT content due to the excellent thermal conductivity of MWNTs. The grain size of MWNT/HA composites decreased with increasing MWNT content and increased with increasing sintering temperature. Pull-out toughening of the MWNTs of the MWNT/HA composites was observed in the fractured surface, which can be used to predict the improvement of the mechanical properties. On the other hand, the existence of undispersed or agglomerate MWNTs in the MWNT/HA composites accompanied large pores. The formation of large pores increased with increasing sintering temperature and MWNT content. The addition of MWNT in HA increased the hardness and fracture toughness by approximately 3~4 times, despite the presence of large pores produced by un-dispersed MWNTs. This provides strong evidence as to why the MWNTs are good candidates as reinforcements for strengthening the ceramic matrix. The MWNT/HA composites did not decompose during SPS sintering. The MWNT-reinforced HA composites were non-toxic and showed a good cell affinity and morphology in vitro for 1 day. PMID:24724100

  14. Highly Conductive Aromatic Functionalized Multi-Walled Carbon Nanotube for Inkjet Printable High Performance Supercapacitor Electrodes

    PubMed Central

    Attri, Pankaj

    2015-01-01

    We report the functionalization of multiwalled carbon nanotubes (MWCNT) via the 1,3-dipolar [3+2] cycloaddition of aromatic azides, which resulted in a detangled CNT as shown by transmission electron microscopy (TEM). Carboxylic moieties (-COOH) on aromatic azide result in highly stable aqueous dispersion (max. conc. ~ 10 mg/mL H2O), making the suitable for inkjet printing. Printed patterns on polyethylene terephthalate (PET) flexible substrate exhibit low sheet resistivity ~65 Ω. cm, which is attributed to enhanced conductivity. Fabricated Supercapacitors (SC) assembled using these printed substrates exhibit good electrochemical performance in organic as well as aqueous electrolytes. High energy and power density (57.8 Wh/kg and 0.85 kW/kg) in 1M H2SO4 aqueous electrolyte demonstrate the excellent performance of the proposed supercapacitor. Capacitive retention varies from ~85–94% with columbic efficiency ~95% after 1000 charge/discharge cycles in different electrolytes, demonstrating the excellent potential of the device for futuristic power applications. PMID:26153688

  15. Adsorption of triazine herbicides from aqueous solution by functionalized multiwall carbon nanotubes grown on silicon substrate

    NASA Astrophysics Data System (ADS)

    D'Archivio, Angelo Antonio; Maggi, Maria Anna; Odoardi, Antonella; Santucci, Sandro; Passacantando, Maurizio

    2018-02-01

    Multi-walled carbon nanotubes (MWCNTs), because of their small size and large available surface area, are potentially efficient sorbents for the extraction of water solutes. Dispersion of MWCNTs in aqueous medium is suitable to adsorb organic contaminants from small sample volumes, but, the recovery of the suspended sorbent for successive re-use represents a critical step, which makes this method inapplicable in large-scale water-treatment technologies. To overcome this problem, we proposed here MWCNTs grown on silicon supports and investigated on a small-volume scale their adsorption properties towards triazine herbicides dissolved in water. The adsorption efficiency of the supported MWCNTs has been tested on seven triazine herbicides, which are emerging water contaminants in Europe and USA, because of their massive use, persistence in soils and potential risks for the aquatic organisms and human health. The investigated compounds, in spite of their common molecular skeleton, cover a relatively large property range in terms of both solubility in water and hydrophilicity/hydrophobicity. The functionalisation of MWCNTs carried out by acidic oxidation, apart from increasing wettability of the material, results in a better adsorption performance. Increasing of functionalisation time between 17 and 60 h progressively increases the extraction of all seven pesticides and produces a moderate increment of selectivity.

  16. Effects of functionalization on thermal properties of single-wall and multi-wall carbon nanotube-polymer nanocomposites.

    PubMed

    Gulotty, Richard; Castellino, Micaela; Jagdale, Pravin; Tagliaferro, Alberto; Balandin, Alexander A

    2013-06-25

    Carboxylic functionalization (-COOH groups) of carbon nanotubes is known to improve their dispersion properties and increase the electrical conductivity of carbon-nanotube-polymer nanocomposites. We have studied experimentally the effects of this type of functionalization on the thermal conductivity of the nanocomposites. It was found that while even small quantities of carbon nanotubes (~1 wt %) can increase the electrical conductivity, a larger loading fraction (~3 wt %) is required to enhance the thermal conductivity of nanocomposites. Functionalized multi-wall carbon nanotubes performed the best as filler material leading to a simultaneous improvement of the electrical and thermal properties of the composites. Functionalization of the single-wall carbon nanotubes reduced the thermal conductivity enhancement. The observed trends were explained by the fact that while surface functionalization increases the coupling between carbon nanotube and polymer matrix, it also leads to formation of defects, which impede the acoustic phonon transport in the single-wall carbon nanotubes. The obtained results are important for applications of carbon nanotubes and graphene flakes as fillers for improving thermal, electrical and mechanical properties of composites.

  17. Mild in situ growth of platinum nanoparticles on multiwalled carbon nanotube-poly (vinyl alcohol) hydrogel electrode for glucose electrochemical oxidation

    NASA Astrophysics Data System (ADS)

    Liu, Shumin; Zheng, Yudong; Qiao, Kun; Su, Lei; Sanghera, Amendeep; Song, Wenhui; Yue, Lina; Sun, Yi

    2015-12-01

    This investigation describes an effective strategy to fabricate an electrochemically active hybrid hydrogel made from platinum nanoparticles that are highly dense, uniformly dispersed, and tightly embedded throughout the conducting hydrogel network for the electrochemical oxidation of glucose. A suspension of multiwalled carbon nanotubes and polyvinyl alcohol aqueous was coated on glassy carbon electrode by electrophoretic deposition and then physically crosslinked to form a three-dimensional porous conductive hydrogel network by a process of freezing and thawing. The network offered 3D interconnected mass-transport channels (around 200 nm) and confined nanotemplates for in situ growth of uniform platinum nanoparticles via the moderate reduction agent, ascorbic acid. The resulting hybrid hydrogel electrode membrane demonstrates an effective method for loading platinum nanoparticles on multiwalled carbon nanotubes by the electrostatic adsorption between multiwalled carbon nanotubes and platinum ions within porous hydrogel network. The average diameter of platinum nanoparticles is 37 ± 14 nm, which is less than the particle size by only using the moderate reduction agent. The hybrid hydrogel electrode membrane-coated glassy carbon electrode showed excellent electrocatalytic activity and good long-term stability toward glucose electrochemical oxidation. The glucose oxidation current exhibited a linear relationship with the concentration of glucose in the presence of chloride ions, promising for potential applications of implantable biofuel cells, biosensors, and electronic devices.

  18. The experimental study of the effect of microwave on the physical properties of multi-walled carbon nanotubes

    SciTech Connect

    Haque, A.K.M. Mahmudul; Oh, Geum Seok; Kim, Taeoh

    Highlights: • We study the microwave effect on the multi-walled carbon nanotubes (MWCNTs). • We examine the non uniform heating effect on the physical structure of MWCNTs. • We examine the purification of MWCNTs by microwave. • We analyze the thermal characteristics of microwave treated MWCNTs. - Abstract: This paper reports the effect of microwave on the physical properties of multi-walled carbon nanotubes (MWCNTs) where different power levels of microwave were applied on MWCNTs in order to apprehend the effect of microwave on MWCNTs distinctly. A low energy ball milling in aqueous circumstance was also applied on both MWCNTs andmore » microwave treated MWCNTs. Temperature profile, morphological analysis by field emission scanning electron microscopy (FESEM), defect analysis by Raman spectroscopy, thermal conductivity, thermal diffusivity as well as heat transfer coefficient enhancement ratio were studied which expose some strong witnesses of the effect of microwave on the both purification and dispersion properties of MWCNTs in base fluid distilled water. The highest thermal conductivity enhancement (6.06% at 40 °C) of MWCNTs based nanofluid is achieved by five minutes microwave treatment as well as wet grinding at 500 rpm for two hours.« less

  19. Aspect ratio has no effect on genotoxicity of multi-wall carbon nanotubes.

    PubMed

    Kim, Jin Sik; Lee, Kyu; Lee, Young Hee; Cho, Hyun Sun; Kim, Ki Heon; Choi, Kyung Hee; Lee, Sang Hee; Song, Kyung Seuk; Kang, Chang Soo; Yu, Il Je

    2011-07-01

    Carbon nanotubes (CNTs) have specific physico-chemical and electrical properties that are useful for telecommunications, medicine, materials, manufacturing processes and the environmental and energy sectors. Yet, despite their many advantages, it is also important to determine whether CNTs may represent a hazard to the environment and human health. Like asbestos, the aspect ratio (length:diameter) and metal components of CNTs are known to have an effect on the toxicity of carbon nanotubes. Thus, to evaluate the toxic potential of CNTs in relation to their aspect ratio and metal contamination, in vivo and in vitro genotoxicity tests were conducted using high-aspect-ratio (diameter: 10-15 nm, length: ~10 μm) and low-aspect-ratio multi-wall carbon nanotubes (MWCNTs, diameter: 10-15 nm, length: ~150 nm) according to OECD test guidelines 471 (bacterial reverse mutation test), 473 (in vitro chromosome aberration test), and 474 (in vivo micronuclei test) with a good laboratory practice system. To determine the treatment concentration for all the tests, a solubility and dispersive test was performed, and a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) solution found to be more suitable than distilled water. Neither the high- nor the low-aspect-ratio MWCNTs induced any genotoxicity in a bacterial reverse mutation test (~1,000 μg/plate), in vitro chromosome aberration test (without S9: ~6.25 μg/ml, with S9: ~50 μg/ml), or in vivo micronuclei test (~50 mg/kg). However, the high-aspect-ratio MWCNTs were found to be more toxic than the low-aspect-ratio MWCNTs. Thus, while high-aspect-ratio MWCNTs do not induce direct genotoxicity or metabolic activation-mediated genotoxicity, genotoxicity could still be induced indirectly through oxidative stress or inflammation.

  20. Reduction of short wavelength reflectance of multi-wall carbon nanotubes through ultraviolet laser irradiation

    NASA Astrophysics Data System (ADS)

    Stephens, Michelle S.; Simonds, Brian J.; Yung, Christopher S.; Conklin, Davis; Livigni, David J.; Oliva, Alberto Remesal; Lehman, John H.

    2018-05-01

    Multi-wall carbon nanotube coatings are used as broadband, low-reflectance absorbers for bolometric applications and for stray light control. They are also used as high emittance blackbody radiators. Irradiation of single wall carbon nanotubes with ultraviolet (UV) laser light has been shown to remove amorphous carbon debris, but there have been few investigations of the interaction of UV light with the more complex physics of multi-wall carbon nanotubes. We present measurements of reflectance and surface morphology before and after exposure of multi-wall carbon nanotube coatings to 248 nm UV laser light. We show that UV exposure reduces the reflectivity at wavelengths below 600 nm and present modeling of the thermal cycling the UV exposure causes at the surface of the carbon nanotubes. This effect can be used to flatten the spectral shape of the reflectivity curve of carbon nanotube absorber coatings used for broadband applications. Finally, we find that the effect of UV exposure depends on the nanotube growth process.

  1. Pressure sensor based on pristine multi-walled carbon nanotubes forest

    NASA Astrophysics Data System (ADS)

    Yasar, M.; Mohamed, N. M.; Hamid, N. H.; Shuaib, M.

    2016-11-01

    In the course of the most recent decade, carbon nanotubes (CNTs) have been developed as alternate material for many sensing applications because of their interesting properties. Their outstanding electromechanical properties make them suitable for pressure/strain sensing application. Other than in view of their structure and number of walls (i.e. Single-Walled CNTs and MultiWalled CNTs), carbon nanotubes can likewise be classified based on their orientation and combined arrangement. One such classification is vertically aligned Multi-Walled Carbon Nanotubes (VA-MWCNTs), regularly termed as CNTs arrays, foam or forest which is macro scale form of CNTs. Elastic behavior alongside exceptional electromechanical (high gauge factor) make it suitable for pressure sensing applications. This paper presents pressure sensor based on such carbon nanotubes forest in pristine form which enables it to perform over wider temperature range as compared to pressure sensors based on conventional materials such as Silicon.

  2. [Comparison study on adsorption of middle molecular substances with multiwalled carbon nanotubes and activated carbon].

    PubMed

    Li, Guifeng; Wan, Jianxin; Huang, Xiangqian; Zeng, Qiao; Tang, Jing

    2011-08-01

    In recent years, multi-walled carbon nanotubes (MWCTs) are very favorable to the adsorption of middle molecular substances in the hemoperfusion because of their multiporous structure, large surface area and high reactivity, which are beneficial to the excellent absorption properties. The purpose of this study was to study the MWCTs on the adsorption capacity of the middle molecular substances. Vitamin B12 (VB12) was selected as a model of the middle molecular substances. The morphologies of MWCTs and activated carbon from commercial "carbon kidney" were observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The adsorption behavior of VB12 was compared to each other with UV-visible absorption spectra. The MWCTs formed a sophistaicate gap structure, and compared to the activated carbon, MWCTs had a larger surface area. By Langmuir equation and Freundlich equation fitting analysis, VB12 adsorption on MWCTs is fit for multi-molecular layer adsorption, and the adsorption type of activated carbon is more inclined to the model corresponding to Langmuir monolayer adsorption. The adsorption rate of MWCTs is faster than that of the activated carbon and the adsorption capacity is greater, which could be expected to become the new adsorbent in the hemoperfusion.

  3. Direct measurement of chiral structure and transport in single- and multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cui, Taoran; Lin, Letian; Qin, Lu-Chang; Washburn, Sean

    2016-11-01

    Electrical devices based on suspended multi-wall carbon nanotubes were constructed and studied. The chiral structure of each shell in a particular nanotube was determined using nanobeam electron diffraction in a transmission electron microscope. The transport properties of the carbon nanotube were also measured. The nanotube device length was short enough that the transport was nearly ballistic, and multiple subbands contributed to the conductance. Thermal excitation of carriers significantly affected nanotube resistance at room temperature.

  4. Multiwalled carbon nanotubes effect on the bioavailability of artemisinin and its cytotoxity to cancerous cells

    NASA Astrophysics Data System (ADS)

    Rezaei, Behzad; Majidi, Najmeh; Noori, Shokoofe; Hassan, Zuhair M.

    2011-12-01

    Artemisinin regarded as one of the most promising anticancer drugs can bind to DNA with a binding constant of 1.04 × 104 M-1. The electrochemical experiments indicated that for longer incubation time periods, the reduction peak current of artemisinin on carbon nanotube modified electrode increases. Therefore, the uptake of drug molecules from a solution into CNTs will be achieved automatically by adsorption of 88.7% of artemisinin onto carbon nanotubes surface without alteration in drug properties. Hence, capability of carbon nanotubes to have synergistic effect on the bioavailability of artemisinin was investigated. Experimental tests on K562 cancer cell lines growth by MTT assay proved that multi-walled carbon nanotubes can enhance the cytotoxity of artemisinin to the targeted cancer cells with unprecedented accuracy and efficiency. The IC50 values were 65 and 35 μM for artemisinin and artemisinin loaded on multi-walled carbon nanotubes, respectively; demonstrating that artemisinin loaded on multi-walled carbon nanotubes is more effective in inhibition of cancer cell lines growth.

  5. Synthesis and characterization of poly lactic acid and multiwall carbon nano-tubes mixtures

    NASA Astrophysics Data System (ADS)

    Kumar LG, Santhosh; del A. Cardona, Rocío; Berríos-Soto, Melvin; Santiago-Avilés, Jorge J.

    2011-10-01

    The motivation for this study is to reproduce processing conditions which lead to the formation of photo or photoinduced thermal actuation, combined with inexpensive, environmentally friendly (easily degradable) materials. Commercially available polymer, poly lactic acid (PLA), was used in our studies. PLA is a well know biodegradable polymer naturally obtained from corn. PLA was received as a solid resin in pellet form and dissolved in 1:3 acetone/chloroform solutions, to achieve the proper electrospinning kinematic viscosity. Once in the liquid phase, the material was mixed with commercially available multi-walled carbon nanotubes (MWCNTs) at varying concentrations and dispersed by severe sonication. The mixtures was electrospun at room temperature using a home built electrospinning apparatus capable of depositing randomly oriented fiber mats or oriented fibers onto different substrates, ranging from oxidized silicon wafers, alumina squares or glass microscope slides. The fibers diameters and lengths are statistically distributed following a log-normal distribution and the mean and dispersion are controlled by spinning parameters. Once the fibers were electrospun, they were compositionally, morphologically and structurally characterized by thermal and gravimetric analysis (TGA/DTA), rheology, imaging using a focused Ion Beam Scanning Electron Microscope (IBSEM), and IR /Raman methodologies. These studies can be used to explore PLA-MWCNTs mixtures suitability in applications such as super-capacitor technology, which would enable us to pursue further research in this field, while focusing on improving the electro spinning conditions so as to be able to better anticipate fiber morphology to generate a consistent regime of fibers.

  6. Deformation and Failure of a Multi-Wall Carbon Nanotube Yarn Composite

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.; Jefferson, Gail D.; Frankland, Sarah-Jane V.

    2008-01-01

    Forests of multi-walled carbon nanotubes can be twisted and manipulated into continuous fibers or yarns that exhibit many of the characteristics of traditional textiles. Macro-scale analysis and test may provide strength and stiffness predictions for a composite composed of a polymer matrix and low-volume fraction yarns. However, due to the nano-scale of the carbon nanotubes, it is desirable to use atomistic calculations to consider tube-tube interactions and the influence of simulated twist on the effective friction coefficient. This paper reports laboratory test data on the mechanical response of a multi-walled, carbon nanotube yarn/polymer composite from both dynamic and quasi-static tensile tests. Macroscale and nano-scale analysis methods are explored and used to define some of the key structure-property relationships. The measured influence of hot-wet aging on the tensile properties is also reported.

  7. Electrochemical biosensing of galactose based on carbon materials: graphene versus multi-walled carbon nanotubes.

    PubMed

    Dalkıran, Berna; Erden, Pınar Esra; Kılıç, Esma

    2016-06-01

    In this study, two enzyme electrodes based on graphene (GR), Co3O4 nanoparticles and chitosan (CS) or multi-walled carbon nanotubes (MWCNTs), Co3O4 nanoparticles, and CS, were fabricated as novel biosensing platforms for galactose determination, and their performances were compared. Galactose oxidase (GaOx) was immobilized onto the electrode surfaces by crosslinking with glutaraldehyde. Optimum working conditions of the biosensors were investigated and the analytical performance of the biosensors was compared with respect to detection limit, linearity, repeatability, and stability. The MWCNTs-based galactose biosensor provided about 1.6-fold higher sensitivity than its graphene counterpart. Moreover, the linear working range and detection limit of the MWCNTs-based galactose biosensor was superior to the graphene-modified biosensor. The successful application of the purposed biosensors for galactose biosensing in human serum samples was also investigated.

  8. Copper Multiwall Carbon Nanotubes and Copper-Diamond Composites for Advanced Rocket Engines

    NASA Technical Reports Server (NTRS)

    Bhat, Biliyar N.; Ellis, Dave L.; Smelyanskiy, Vadim; Foygel, Michael; Singh, Jogender; Rape, Aaron; Vohra, Yogesh; Thomas, Vinoy; Li, Deyu; Otte, Kyle

    2013-01-01

    This paper reports on the research effort to improve the thermal conductivity of the copper-based alloy NARloy-Z (Cu-3 wt.%Ag-0.5 wt.% Zr), the state-of-the-art alloy used to make combustion chamber liners in regeneratively-cooled liquid rocket engines, using nanotechnology. The approach was to embed high thermal conductivity multiwall carbon nanotubes (MWCNTs) and diamond (D) particles in the NARloy-Z matrix using powder metallurgy techniques. The thermal conductivity of MWCNTs and D have been reported to be 5 to 10 times that of NARloy-Z. Hence, 10 to 20 vol. % MWCNT finely dispersed in NARloy-Z matrix could nearly double the thermal conductivity, provided there is a good thermal bond between MWCNTs and copper matrix. Quantum mechanics-based modeling showed that zirconium (Zr) in NARloy-Z should form ZrC at the MWCNT-Cu interface and provide a good thermal bond. In this study, NARloy-Z powder was blended with MWCNTs in a ball mill, and the resulting mixture was consolidated under high pressure and temperature using Field Assisted Sintering Technology (FAST). Microstructural analysis showed that the MWCNTs, which were provided as tangles of MWCNTs by the manufacturer, did not detangle well during blending and formed clumps at the prior particle boundaries. The composites made form these powders showed lower thermal conductivity than the base NARloy-Z. To eliminate the observed physical agglomeration, tangled multiwall MWCNTs were separated by acid treatment and electroless plated with a thin layer of chromium to keep them separated during further processing. Separately, the thermal conductivities of MWCNTs used in this work were measured, and the results showed very low values, a major factor in the low thermal conductivity of the composite. On the other hand, D particles embedded in NARloy-Z matrix showed much improved thermal conductivity. Elemental analysis showed migration of Zr to the NARloy-Z-D interface to form ZrC, which appeared to provide a low contact

  9. Copper-Multiwall Carbon Nanotubes and Copper-Diamond Composites for Advanced Rocket Engines

    NASA Technical Reports Server (NTRS)

    Bhat, Biliyar N.; Ellis, Dave L.; Smelyanskiy, Vadim; Foygel, Michael; Rape, Aaron; Singh, Jogender; Vohra, Yogesh K.; Thomas, Vinoy; Otte, Kyle G.; Li, Deyu

    2013-01-01

    This paper reports on the research effort to improve the thermal conductivity of the copper-based alloy NARloy-Z (Cu-3 wt.%Ag-0.5 wt.% Zr), the state-of-the-art alloy used to make combustion chamber liners in regeneratively-cooled liquid rocket engines, using nanotechnology. The approach was to embed high thermal conductivity multiwall carbon nanotubes (MWCNTs) and diamond (D) particles in the NARloy-Z matrix using powder metallurgy techniques. The thermal conductivity of MWCNTs and D have been reported to be 5 to 10 times that of NARloy-Z. Hence, 10 to 20 vol. % MWCNT finely dispersed in NARloy-Z matrix could nearly double the thermal conductivity, provided there is a good thermal bond between MWCNTs and copper matrix. Quantum mechanics-based modeling showed that zirconium (Zr) in NARloy-Z should form ZrC at the MWCNT-Cu interface and provide a good thermal bond. In this study, NARloy-Z powder was blended with MWCNTs in a ball mill, and the resulting mixture was consolidated under high pressure and temperature using Field Assisted Sintering Technology (FAST). Microstructural analysis showed that the MWCNTs, which were provided as tangles of MWCNTs by the manufacturer, did not detangle well during blending and formed clumps at the prior particle boundaries. The composites made form these powders showed lower thermal conductivity than the base NARloy-Z. To eliminate the observed physical agglomeration, tangled multiwall MWCNTs were separated by acid treatment and electroless plated with a thin layer of chromium to keep them separated during further processing. Separately, the thermal conductivities of MWCNTs used in this work were measured, and the results showed very low values, a major factor in the low thermal conductivity of the composite. On the other hand, D particles embedded in NARloy-Z matrix showed much improved thermal conductivity. Elemental analysis showed migration of Zr to the NARloy-Z-D interface to form ZrC, which appeared to provide a low contact

  10. Simultaneous electrochemical determination of dopamine and paracetamol on multiwalled carbon nanotubes/graphene oxide nanocomposite-modified glassy carbon electrode.

    PubMed

    Cheemalapati, Srikanth; Palanisamy, Selvakumar; Mani, Veerappan; Chen, Shen-Ming

    2013-12-15

    In the present study, multiwalled carbon nanotubes (MWCNT)/graphene oxide (GO) nanocomposite was prepared by homogenous dispersion of MWCNT and GO and used for the simultaneous voltammetric determination of dopamine (DA) and paracetamol (PA). The TEM results confirmed that MWCNT walls were wrapped well with GO sheets. The MWCNT/GO nanocomposite showed superior electrocatalytic activity towards the oxidation of DA and PA, when compared with either pristine MWCNT or GO. The major reason for the efficient simultaneous detection of DA and PA at nanocomposite was the synergistic effect between MWCNT and GO. The electrochemical oxidation of DA and PA was investigated by cyclic voltammetry, differential pulse voltammetry and amperometry. The nanocomposite modified electrode showed electrocatalytic oxidation of DA and PA in the linear response range from 0.2 to 400 µmol L(-1) and 0.5 to 400 µmol L(-1) with the detection limit of 22 nmol L(-1) and 47 nmol L(-1) respectively. The proposed sensor displayed good selectivity, sensitivity, stability with appreciable consistency and precision. © 2013 Elsevier B.V. All rights reserved.

  11. A facile synthesis of zinc oxide/multiwalled carbon nanotube nanocomposite lithium ion battery anodes by sol-gel method

    NASA Astrophysics Data System (ADS)

    Köse, Hilal; Karaal, Şeyma; Aydın, Ali Osman; Akbulut, Hatem

    2015-11-01

    Free standing zinc oxide (ZnO) and multiwalled carbon nanotube (MWCNT) nanocomposite materials are prepared by a sol gel technique giving a new high capacity anode material for lithium ion batteries. Free-standing ZnO/MWCNT nanocomposite anodes with two different chelating agent additives, triethanolamine (TEA) and glycerin (GLY), yield different electrochemical performances. Field emission gun scanning electron microscopy (FEG-SEM), energy dispersive X-ray spectrometer (EDS), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) analyses reveal the produced anode electrodes exhibit a unique structure of ZnO coating on the MWCNT surfaces. Li-ion cell assembly using a ZnO/MWCNT/GLY free-standing anode and Li metal cathode possesses the best discharge capacity, remaining as high as 460 mAh g-1 after 100 cycles. This core-shell structured anode can offer increased energy storage and performance over conventional anodes in Li-ion batteries.

  12. Ultrasonically treated multi-walled carbon nanotubes (MWCNTs) as PtRu catalyst supports for methanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Yang, Chunwei; Hu, Xinguo; Wang, Dianlong; Dai, Changsong; Zhang, Liang; Jin, Haibo; Agathopoulos, Simeon

    In the quest of fabricating supported catalysts, experimental results of transmission electron microscopy, Raman and infrared spectroscopy indicate that ultrasonic treatment effectively functionalizes multi-walled carbon nanotubes (MWCNTs), endowing them with groups that can act as nucleation sites which can favor well-dispersed depositions of PtRu clusters on their surface. Ultrasonic treatment seems to be superior than functionalization via regular refluxing. This is confirmed by the determination of the electrochemistry active surface area (ECA) and the CO-tolerance performance of the PtRu catalysts, measured by adsorbed CO-stripping voltammetry in 0.5 M sulfuric acid solution, and the real surface area of the PtRu catalysts, evaluated by Brunauer-Emmett-Teller (BET) measurements. Finally, the effectiveness for methanol oxidation is assessed by cyclic voltammetry (CV) in a sulfuric acid and methanol electrolyte.

  13. Inflammation response at the transcriptional level of HepG2 cells induced by multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Piret, Jean-Pascal; Vankoningsloo, Sébastien; Noël, Florence; Mejia Mendoza, Jorge; Lucas, Stéphane; Saout, Christelle; Toussaint, Olivier

    2011-07-01

    Poor information are currently available about the biological effects of multi-walled carbon nanotubes (MWCNT) on the liver. In this study, we evaluated the effects of MWCNT at the transcriptional level on the classical in vitro model of HepG2 hepatocarcinoma cells. The expression levels of 96 transcript species implicated in the inflammatory and immune responses was studied after a 24h incubation of HepG2 cells in presence of raw MWCNT dispersed in water by stirring. Among the 46 transcript species detected, only a few transcripts including mRNA coding for interleukine-7, chemokines receptor of the C-C families CCR7, as well as Endothelin-1, were statistically more abundant after treatment with MWCNT. Altogether, these data indicate that MWCNT can only induce a weak inflammatory response in HepG2 cells.

  14. Experimental consideration of the Hansen solubility parameters of as-produced multi-walled carbon nanotubes by inverse gas chromatography.

    PubMed

    Lim, Hyeong Jun; Lee, Kunsil; Cho, Young Shik; Kim, Yern Seung; Kim, Taehoon; Park, Chong Rae

    2014-09-07

    The Hansen solubility parameters (HSPs) of as-produced multi-walled carbon nanotubes (APMWCNTs) were determined by means of the inverse gas chromatography (IGC) technique. Due to non-homogeneous surfaces of the APMWCNTs arising from defects and impurities, it was necessary to establish adequate working conditions for determining the HSPs of the CNTs. We then obtained the HSPs of the APMWCNTs and compared these results with earlier reports as determined by using sedimentation and molecular dynamics simulation methods. It was found that the determination of the HSPs of the CNTs by IGC can give an enhanced determination range based on the adsorption thermodynamic parameters, compared to the HSPs determined using sedimentation methods. And the HSPs of the APMWCNTs, determined here, provided good guidelines for the selection of feasible solvents that can improve the dispersion of the APMWCNTs.

  15. Core/shell, protuberance-free multiwalled carbon nanotube/polyaniline nanocomposites via interfacial chemistry of aryl diazonium salts.

    PubMed

    Mekki, Ahmed; Samanta, Soumen; Singh, Ajay; Salmi, Zakaria; Mahmoud, Rachid; Chehimi, Mohamed M; Aswal, Dinesh K

    2014-03-15

    Highly uniform core-shell like multi-walled carbon nanotubes-polyaniline (MWCNT-PANI) nanocomposites were prepared in two steps (i) surface modification of MWCNTs with a 4-aminodiphenylamine group via in situ diazonium generation process; and (ii) polymerization of aniline onto surface modified MWCNTs. This functionalization helped to easily disperse the MWCNTs in acidic solutions; hence it is suitable for the chemical oxidative polymerization of aniline. It was found that MWCNT-PANI nano-composites with higher MWCNTs loading yield PANI chains with more quinoid units than the pure PANI, which results in significant improvement in the conductivity of the composites. This facile approach of synthesizing core-shell nanocomposites highlights the efficiency of the interfacial chemistry of aryl diazonium salts in generating conductive polymer/MWCNT nanocomposites with enhanced conductivity and high surface area. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Effective load transfer by a chromium carbide nanostructure in a multi-walled carbon nanotube/copper matrix composite

    NASA Astrophysics Data System (ADS)

    Cho, Seungchan; Kikuchi, Keiko; Kawasaki, Akira; Kwon, Hansang; Kim, Yangdo

    2012-08-01

    Multi-walled carbon nanotube (MWCNT) reinforced copper (Cu) matrix composites, which exhibit chromium (Cr) carbide nanostructures at the MWCNT/Cu interface, were prepared through a carbide formation using CuCr alloy powder. The fully densified and oriented MWCNTs dispersed throughout the composites were prepared using spark plasma sintering (SPS) followed by hot extrusion. The tensile strengths of the MWCNT/CuCr composites increased with increasing MWCNTs content, while the tensile strength of MWCNT/Cu composite decreased from that of monolithic Cu. The enhanced tensile strength of the MWCNT/CuCr composites is a result of possible load-transfer mechanisms of the interfacial Cr carbide nanostructures. The multi-wall failure of MWCNTs observed in the fracture surface of the MWCNT/CuCr composites indicates an improvement in the load-bearing capacity of the MWCNTs. This result shows that the Cr carbide nanostructures effectively transferred the tensile load to the MWCNTs during fracture through carbide nanostructure formation in the MWCNT/Cu composite.

  17. Fabrication of enzyme-based coatings on intact multi-walled carbon nanotubes as highly effective electrodes in biofuel cells

    NASA Astrophysics Data System (ADS)

    Kim, Byoung Chan; Lee, Inseon; Kwon, Seok-Joon; Wee, Youngho; Kwon, Ki Young; Jeon, Chulmin; An, Hyo Jin; Jung, Hee-Tae; Ha, Su; Dordick, Jonathan S.; Kim, Jungbae

    2017-01-01

    CNTs need to be dispersed in aqueous solution for their successful use, and most methods to disperse CNTs rely on tedious and time-consuming acid-based oxidation. Here, we report the simple dispersion of intact multi-walled carbon nanotubes (CNTs) by adding them directly into an aqueous solution of glucose oxidase (GOx), resulting in simultaneous CNT dispersion and facile enzyme immobilization through sequential enzyme adsorption, precipitation, and crosslinking (EAPC). The EAPC achieved high enzyme loading and stability because of crosslinked enzyme coatings on intact CNTs, while obviating the chemical pretreatment that can seriously damage the electron conductivity of CNTs. EAPC-driven GOx activity was 4.5- and 11-times higher than those of covalently-attached GOx (CA) on acid-treated CNTs and simply-adsorbed GOx (ADS) on intact CNTs, respectively. EAPC showed no decrease of GOx activity for 270 days. EAPC was employed to prepare the enzyme anodes for biofuel cells, and the EAPC anode produced 7.5-times higher power output than the CA anode. Even with a higher amount of bound non-conductive enzymes, the EAPC anode showed 1.7-fold higher electron transfer rate than the CA anode. The EAPC on intact CNTs can improve enzyme loading and stability with key routes of improved electron transfer in various biosensing and bioelectronics devices.

  18. Multi-walled carbon nanotube (MWCNT) synthesis, preparation, labeling, and functionalization.

    PubMed

    Kateb, Babak; Yamamoto, Vicky; Alizadeh, Darya; Zhang, Leying; Manohara, Harish M; Bronikowski, Michael J; Badie, Behnam

    2010-01-01

    Nanomedicine is a growing field with a great potential for introducing new generation of targeted and personalized drug. Amongst new generation of nano-vectors are carbon nanotubes (CNTs), which can be produced as single or multi-walled. Multi-walled carbon nanotubes (MWCNTs) can be fabricated as biocompatible nanostructures (cylindrical bulky tubes). These structures are currently under investigation for their application in nanomedicine as viable and safe nanovectors for gene and drug delivery. In this chapter, we will provide you with the necessary information to understand the synthesis of MWCNTs, functionalization, PKH26 labeling, RNAi, and DNA loading for in vitro experimentation and in vivo implantation of labeled MWCNT in mice as well as materials used in this experimentation. We used this technique to manipulate microglia as part of a novel application for the brain cancer immunotherapy. Our published data show this is a promising technique for labeling, and gene and drug delivery into microglia.

  19. Heterodoped nanotubes: theory, synthesis, and characterization of phosphorus-nitrogen doped multiwalled carbon nanotubes.

    PubMed

    Cruz-Silva, Eduardo; Cullen, David A; Gu, Lin; Romo-Herrera, Jose Manuel; Muñoz-Sandoval, Emilio; López-Urías, Florentino; Sumpter, Bobby G; Meunier, Vincent; Charlier, Jean-Christophe; Smith, David J; Terrones, Humberto; Terrones, Mauricio

    2008-03-01

    Arrays of multiwalled carbon nanotubes doped with phosphorus (P) and nitrogen (N) are synthesized using a solution of ferrocene, triphenyl-phosphine, and benzylamine in conjunction with spray pyrolysis. We demonstrate that iron phosphide (Fe(3)P) nanoparticles act as catalysts during nanotube growth, leading to the formation of novel PN-doped multiwalled carbon nanotubes. The samples were examined by high resolution electron microscopy and microanalysis techniques, and their chemical stability was explored by means of thermogravimetric analysis in the presence of oxygen. The PN-doped structures reveal important morphology and chemical changes when compared to N-doped nanotubes. These types of heterodoped nanotubes are predicted to offer many new opportunities in the fabrication of fast-response chemical sensors.

  20. Electrochemical reduction of nalidixic acid at glassy carbon electrode modified with multi-walled carbon nanotubes.

    PubMed

    Patiño, Yolanda; Pilehvar, Sanaz; Díaz, Eva; Ordóñez, Salvador; De Wael, Karolien

    2017-02-05

    The aqueous phase electrochemical degradation of nalidixic acid (NAL) is studied in this work, using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) as instrumental techniques. The promotional effect of multi-walled carbon nanotubes (MWCNT) on the performance of glassy carbon electrodes is demonstrated, being observed that these materials catalyze the NAL reduction. The effect of surface functional groups on MWCNT -MWCNT-COOH and MWCNT-NH 2 -was also studied. The modification of glassy carbon electrode (GCE) with MWCNT leads to an improved performance for NAL reduction following the order of MWCNT>MWCNT-NH 2 >MWCNT-COOH. The best behavior at MWCNT-GCE is mainly due to both the increased electrode active area and the enhanced MWCNT adsorption properties. The NAL degradation was carried out under optimal conditions (pH=5.0, deposition time=20s and volume of MWCNT=10μL) using MWCNT-GCE obtaining an irreversible reduction of NAL to less toxic products. Paramaters as the number of DPV cycles and the volume/area (V/A) ratio were optimized for maximize pollutant degradation. It was observed that after 15 DPV scans and V/A=8, a complete reduction was obtained, obtaining two sub-products identified by liquid chromatography-mass spectrometry (LC-MS). Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Patterned forests of vertically-aligned multiwalled carbon nanotubes using metal salt catalyst solutions.

    PubMed

    Garrett, David J; Flavel, Benjamin S; Baronian, Keith H R; Downard, Alison J

    2013-01-01

    A simple method for producing patterned forests of multiwalled carbon nanotubes (MWCNTs) is described. An aqueous metal salt solution is spin-coated onto a substrate patterned with photoresist by standard methods. The photoresist is removed by acetone washing leaving the acetone-insoluble catalyst pattern on the substrate. Dense forests of vertically aligned (VA) MWCNTs are grown on the patterned catalyst layers by chemical vapour deposition. The procedures have been demonstrated by growing MWCNT forests on two substrates: silicon and conducting graphitic carbon films. The forests adhere strongly to the substrates and when grown directly on carbon film, offer a simple method of preparing MWCNT electrodes.

  2. Atomic Layer Deposition on Gram Quantities of Multi-Walled Carbon Nanotubes

    DTIC Science & Technology

    2009-06-03

    the amount of reactant that is lost to the vacuum pump . Recent work has demonstrated the feasibility of ALD on gram quantities of nanopowders in a...and left to outgas under vacuum for 24 h. Vacuum was obtained using a dual-stage rotary vane pump . Pressure was monitored with a Baratron capacitance...Atomic layer deposition on gram quantities of multi-walled carbon nanotubes This article has been downloaded from IOPscience. Please scroll down to

  3. Multi-wall carbon nanotube@zeolite imidazolate framework composite from a nanoscale zinc oxide precursor

    DOE PAGES

    Yue, Yanfeng; Guo, Bingkun; Qiao, Zhenan; ...

    2014-07-24

    Nanocomposite of multi-walled carbon nanotube@zeolite imidazolate frameworks (MWNT@ZIF) was prepared through a nanotube-facilitated growth based on a nanosized ZnO precursor. The electrically conductive nanocomposite displays a capacity of 380 mAh/g at 0.1 °C in Li–sulfur battery, transforming electrically inactive ZIF into the active one for battery applications.

  4. Nano-engineered Multiwall Carbon Nanotube-copper Composite Thermal Interface Material for Efficient Heat Conduction

    NASA Technical Reports Server (NTRS)

    Ngo, Quoc; Cruden, Brett A.; Cassell, Alan M.; Sims, Gerard; Li, Jun; Meyyappa, M.; Yang, Cary Y.

    2005-01-01

    Efforts in integrated circuit (IC) packaging technologies have recently been focused on management of increasing heat density associated with high frequency and high density circuit designs. While current flip-chip package designs can accommodate relatively high amounts of heat density, new materials need to be developed to manage thermal effects of next-generation integrated circuits. Multiwall carbon nanotubes (MWNT) have been shown to significantly enhance thermal conduction in the axial direction and thus can be considered to be a candidate for future thermal interface materials by facilitating efficient thermal transport. This work focuses on fabrication and characterization of a robust MWNT-copper composite material as an element in IC package designs. We show that using vertically aligned MWNT arrays reduces interfacial thermal resistance by increasing conduction surface area, and furthermore, the embedded copper acts as a lateral heat spreader to efficiently disperse heat, a necessary function for packaging materials. In addition, we demonstrate reusability of the material, and the absence of residue on the contacting material, both novel features of the MWNT-copper composite that are not found in most state-of-the-art thermal interface materials. Electrochemical methods such as metal deposition and etch are discussed for the creation of the MWNT-Cu composite, detailing issues and observations with using such methods. We show that precise engineering of the composite surface affects the ability of this material to act as an efficient thermal interface material. A thermal contact resistance measurement has been designed to obtain a value of thermal contact resistance for a variety of different thermal contact materials.

  5. Fabrication of nanoscale to macroscale nickel-multiwall carbon nanotube hybrid materials with tunable material properties

    NASA Astrophysics Data System (ADS)

    Abdalla, Ahmed M.; Majdi, Tahereh; Ghosh, Suvojit; Puri, Ishwar K.

    2016-12-01

    To utilize their superior properties, multiwall carbon nanotubes (MWNTs) must be manipulated and aligned end-to-end. We describe a nondestructive method to magnetize MWNTs and provide a means to remotely manipulate them through the electroless deposition of magnetic nickel nanoparticles on their surfaces. The noncovalent bonds between Ni nanoparticles and MWNTs produce a Ni-MWNT hybrid material (NiCH) that is electrically conductive and has an enhanced magnetic susceptibility and elastic modulus. Our experiments show that MWNTs can be plated with Ni for Ni:MWNT weight ratios of γ = 1, 7, 14 and 30, to control the material properties. The phase, atom-level, and morphological information from x-ray diffraction, energy dispersive x-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, dark field STEM, and atomic force microscopy clarify the plating process and reveal the mechanical properties of the synthesized material. Ni metalizes at the surface of the Pd catalyst, forming a continuous wavy layer that encapsulates the MWNT surfaces. Subsequently, Ni acts as an autocatalyst, allowing the plating to continue even after the original Pd catalyst has been completely covered. Raising γ increases the coating layer thickness from 10 to 150 nm, which influences the NiCH magnetic properties and tunes its elastic modulus from 12.5 to 58.7 GPa. The NiCH was used to fabricate Ni-MWNT macrostructures and tune their morphologies by changing the direction of an applied magnetic field. Leveraging the hydrophilic Ni-MWNT outer surface, a water-based conductive ink was created and used to print a conductive path that had an electrical resistivity of 5.9 Ω m, illustrating the potential of this material for printing electronic circuits.

  6. Dispersion toughened silicon carbon ceramics

    DOEpatents

    Wei, G.C.

    1984-01-01

    Fracture resistant silicon carbide ceramics are provided by incorporating therein a particulate dispersoid selected from the group consisting of (a) a mixture of boron, carbon and tungsten, (b) a mixture of boron, carbon and molybdenum, (c) a mixture of boron, carbon and titanium carbide, (d) a mixture of aluminum oxide and zirconium oxide, and (e) boron nitride. 4 figures.

  7. Pristine multi-walled carbon nanotubes/SDS modified carbon paste electrode as an amperometric sensor for epinephrine.

    PubMed

    Thomas, Tony; Mascarenhas, Ronald J; D' Souza, Ozma J; Detriche, Simon; Mekhalif, Zineb; Martis, Praveen

    2014-07-01

    An amperometric sensor for the determination of epinephrine (EP) was fabricated by modifying the carbon paste electrode (CPE) with pristine multi-walled carbon nanotubes (pMWCNTs) using bulk modification followed by drop casting of sodium dodecyl sulfate (SDS) onto the surface for its optimal potential application. The modified electrode showed an excellent electrocatalytic activity towards EP by decreasing the overpotential and greatly enhancing the current sensitivity. FE-SEM images confirmed the dispersion of pMWCNTs in the CPE matrix. EDX analysis ensured the surface coverage of SDS. A comparative study of pMWCNTs with those of oxidized MWCNTs (MWCNTsOX) modified electrodes reveals that the former is the best base material for the construction of the sensor with advantages of lower oxidation overpotential and the least background current. The performance of the modified electrode was impressive in terms of the least charge transfer resistance (Rct), highest values for diffusion coefficient (DEP) and standard heterogeneous electron transfer rate constant (k°). Analytical characterization of the modified electrode exhibited two linear dynamic ranges from 1.0×10(-7) to 1.0×10(-6)M and 1.0×10(-6) to 1.0×10(-4)M with a detection limit of (4.5±0.18)×10(-8)M. A 100-fold excess of serotonin, acetaminophen, folic acid, uric acid, tryptophan, tyrosine and cysteine, 10-fold excess of ascorbic acid and twofold excess of dopamine do not interfere in the quantification of EP at this electrode. The analytical applications of the modified electrode were demonstrated by determining EP in spiked blood serum and adrenaline tartrate injection. The modified electrode involves a simple fabrication procedure, minimum usage of the modifier, quick response, excellent stability, reproducibility and anti-fouling effects. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. The effects of liquid-phase oxidation of multiwall carbon nanotubes on their surface characteristics

    NASA Astrophysics Data System (ADS)

    Burmistrov, I. N.; Muratov, D. S.; Ilinykh, I. A.; Kolesnikov, E. A.; Godymchuk, A. Yu; Kuznetsov, D. V.

    2016-01-01

    The development of new sorbents based on nanostructured carbon materials recently became a perspective field of research. Main topic of current study is to investigate the effect of different regimes of multiwall carbon nanotubes (MWCNT) surface modification process on their structural characteristics. MWCNT samples were treated with nitric acid at high temperature. Structural properties were studied using low temperature nitrogen adsorption and acid-base back titration methods. The study showed that diluted nitric acid does not affect MWCNT structure. Concentrated nitric acid treatment leads to formation of 2.8 carboxylic groups per 1 nm2 of the sample surface.

  9. Evaluating the biological risk of functionalized multiwalled carbon nanotubes and functionalized oxygen-doped multiwalled carbon nanotubes as possible toxic, carcinogenic, and embryotoxic agents

    PubMed Central

    Lara-Martínez, Luis A; Massó, Felipe; Palacios González, Eduardo; García-Peláez, Isabel; Contreras–Ramos, Alejandra; Valverde, Mahara; Rojas, Emilio; Cervantes-Sodi, Felipe; Hernández-Gutiérrez, Salomón

    2017-01-01

    Carbon nanotubes (CNTs) have been a focus of attention due to their possible applications in medicine, by serving as scaffolds for cell growth and proliferation and improving mesenchymal cell transplantation and engraftment. The emphasis on the benefits of CNTs has been offset by the ample debate on the safety of nanotechnologies. In this study, we determine whether functionalized multiwalled CNTs (fMWCNTs) and functionalized oxygen-doped multiwalled CNTs (fCOxs) have toxic effects on rat mesenchymal stem cells (MSCs) in vitro by analyzing morphology and cell proliferation and, using in vivo models, whether they are able to transform MSCs in cancer cells or induce embryotoxicity. Our results demonstrate that there are statistically significant differences in cell proliferation and the cell cycle of MSCs in culture. We identified dramatic changes in cells that were treated with fMWCNTs. Our evaluation of the transformation to cancer cells and cytotoxicity process showed little effect. However, we found a severe embryotoxicity in chicken embryos that were treated with fMWCNTs, while fCOxs seem to exert cardioembryotoxicity and a discrete teratogenicity. Furthermore, it seems that the time of contact plays an important role during cell transformation and embryotoxicity. A single contact with fMWCNTs is not sufficient to transform cells in a short time; an exposure of fMWCNTs for 2 weeks led to cell transformation risk and cardioembryotoxicity effects. PMID:29089764

  10. Evaluating the biological risk of functionalized multiwalled carbon nanotubes and functionalized oxygen-doped multiwalled carbon nanotubes as possible toxic, carcinogenic, and embryotoxic agents.

    PubMed

    Lara-Martínez, Luis A; Massó, Felipe; Palacios González, Eduardo; García-Peláez, Isabel; Contreras-Ramos, Alejandra; Valverde, Mahara; Rojas, Emilio; Cervantes-Sodi, Felipe; Hernández-Gutiérrez, Salomón

    2017-01-01

    Carbon nanotubes (CNTs) have been a focus of attention due to their possible applications in medicine, by serving as scaffolds for cell growth and proliferation and improving mesenchymal cell transplantation and engraftment. The emphasis on the benefits of CNTs has been offset by the ample debate on the safety of nanotechnologies. In this study, we determine whether functionalized multiwalled CNTs (fMWCNTs) and functionalized oxygen-doped multiwalled CNTs (fCOxs) have toxic effects on rat mesenchymal stem cells (MSCs) in vitro by analyzing morphology and cell proliferation and, using in vivo models, whether they are able to transform MSCs in cancer cells or induce embryotoxicity. Our results demonstrate that there are statistically significant differences in cell proliferation and the cell cycle of MSCs in culture. We identified dramatic changes in cells that were treated with fMWCNTs. Our evaluation of the transformation to cancer cells and cytotoxicity process showed little effect. However, we found a severe embryotoxicity in chicken embryos that were treated with fMWCNTs, while fCOxs seem to exert cardioembryotoxicity and a discrete teratogenicity. Furthermore, it seems that the time of contact plays an important role during cell transformation and embryotoxicity. A single contact with fMWCNTs is not sufficient to transform cells in a short time; an exposure of fMWCNTs for 2 weeks led to cell transformation risk and cardioembryotoxicity effects.

  11. Parameterizing A Surface Water Model for Multiwalled Carbon Nanotubes

    EPA Science Inventory

    The unique electronic, mechanical, and structural properties of carbon nanotubes (CNTs) has lead to increasing production of these versatile materials; currently, the use of carbon-based nanomaterials in consumer products is second only to that of nano-scale silver. Although ther...

  12. Effects of nitrogen-doped multi-walled carbon nanotubes compared to pristine multi-walled carbon nanotubes on human small airway epithelial cells.

    PubMed

    Mihalchik, Amy L; Ding, Weiqiang; Porter, Dale W; McLoughlin, Colleen; Schwegler-Berry, Diane; Sisler, Jennifer D; Stefaniak, Aleksandr B; Snyder-Talkington, Brandi N; Cruz-Silva, Rodolfo; Terrones, Mauricio; Tsuruoka, Shuji; Endo, Morinobu; Castranova, Vincent; Qian, Yong

    2015-07-03

    Nitrogen-doped multi-walled carbon nanotubes (ND-MWCNTs) are modified multi-walled carbon nanotubes (MWCNTs) with enhanced electrical properties that are used in a variety of applications, including fuel cells and sensors; however, the mode of toxic action of ND-MWCNT has yet to be fully elucidated. In the present study, we compared the interaction of ND-MWCNT or pristine MWCNT-7 with human small airway epithelial cells (SAEC) and evaluated their subsequent bioactive effects. Transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction suggested the presence of N-containing defects in the lattice of the nanotube. The ND-MWCNTs were determined to be 93.3% carbon, 3.8% oxygen, and 2.9% nitrogen. A dose-response cell proliferation assay showed that low doses of ND-MWCNT (1.2μg/ml) or MWCNT-7 (0.12μg/ml) increased cellular proliferation, while the highest dose of 120μg/ml of either material decreased proliferation. ND-MWCNT and MWCNT-7 appeared to interact with SAEC at 6h and were internalized by 24h. ROS were elevated at 6 and 24h in ND-MWCNT exposed cells, but only at 6h in MWCNT-7 exposed cells. Significant alterations to the cell cycle were observed in SAEC exposed to either 1.2μg/ml of ND-MWCNT or MWCNT-7 in a time and material-dependent manner, possibly suggesting potential damage or alterations to cell cycle machinery. Our results indicate that ND-MWCNT induce effects in SAEC over a time and dose-related manner which differ from MWCNT-7. Therefore, the physicochemical characteristics of the materials appear to alter their biological effects. Published by Elsevier Ireland Ltd.

  13. Dispersion of carbon nanotubes in melt compounded polypropylene based composites investigated by THz spectroscopy.

    PubMed

    Casini, R; Papari, G; Andreone, A; Marrazzo, D; Patti, A; Russo, P

    2015-07-13

    We investigate the use of Terahertz (THz) Time Domain Spectroscopy (TDS) as a tool for the measurement of the index dispersion of multi-walled carbon nanotubes (MWCNT) in polypropylene (PP) based composites. Samples containing 0.5% by volume concentration of non-functionalized and functionalized carbon nanotubes are prepared by melt compounding technology. Results indicate that the THz response of the investigated nanocomposites is strongly dependent on the kind of nanotube functionalization, which in turn impacts on the level of dispersion inside the polymer matrix. We show that specific dielectric parameters such as the refractive index and the absorption coefficient measured by THz spectroscopy can be both correlated to the index of dispersion as estimated using conventional optical microscopy.

  14. Multi-walled Carbon Nanotubes/Graphite Nanosheets Modified Glassy Carbon Electrode for the Simultaneous Determination of Acetaminophen and Dopamine.

    PubMed

    Zhang, Susu; He, Ping; Zhang, Guangli; Lei, Wen; He, Huichao

    2015-01-01

    Graphite nanosheets prepared by thermal expansion and successive sonication were utilized for the construction of a multi-walled carbon nanotubes/graphite nanosheets based amperometric sensing platform to simultaneously determine acetaminophen and dopamine in the presence of ascorbic acid in physiological conditions. The synergistic effect of multi-walled carbon nanotubes and graphite nanosheets catalyzed the electrooxidation of acetaminophen and dopamine, leading to a remarkable potential difference up to 200 mV. The as-prepared modified electrode exhibited linear responses to acetaminophen and dopamine in the concentration ranges of 2.0 × 10(-6) - 2.4 × 10(-4) M (R = 0.999) and 2.0 × 10(-6) - 2.0 × 10(-4) M (R = 0.998), respectively. The detection limits were down to 2.3 × 10(-7) M for acetaminophen and 3.5 × 10(-7) M for dopamine (S/N = 3). Based on the simple preparation and prominent electrochemical properties, the obtained multi-walled carbon nanotubes/graphite nanosheets modified electrode would be a good candidate for the determination of acetaminophen and dopamine without the interference of ascorbic acid.

  15. The effect of extended polymer chains on the properties of transparent multi-walled carbon nanotubes/poly(methyl methacrylate/acrylic acid) film

    NASA Astrophysics Data System (ADS)

    Huang, Yuan-Li; Tien, Hsi-Wen; Ma, Chen-Chi M.; Yu, Yi-Hsiuan; Yang, Shin-Yi; Wei, Ming-Hsiung; Wu, Sheng-Yen

    2010-05-01

    Optically transparent and electrically conductive thin films composed of multi-walled carbon nanotube (MWCNT) reinforced polymethyl methacrylate/acrylic acid (PMMA/AA) were fabricated using a wire coating technique. Poly(acrylic acid) controls the level of MWCNT dispersion in aqueous mixtures and retains the well-dispersed state in the polymer matrix after solidification resulting from extended polymer chains by adjusting the pH value. The exfoliating the MWCNT bundles by extended polymer chains results in the excellent dispersion of MWCNT. It causes a lower surface electrical resistance at the same MWCNT content. The hydrophilic functional groups (-COO - NA + ) also caused a decrease in the crystallization of PMMA and led to an increase in the transmittance.

  16. The effect of extended polymer chains on the properties of transparent multi-walled carbon nanotubes/poly(methyl methacrylate/acrylic acid) film.

    PubMed

    Huang, Yuan-Li; Tien, Hsi-Wen; Ma, Chen-Chi M; Yu, Yi-Hsiuan; Yang, Shin-Yi; Wei, Ming-Hsiung; Wu, Sheng-Yen

    2010-05-07

    Optically transparent and electrically conductive thin films composed of multi-walled carbon nanotube (MWCNT) reinforced polymethyl methacrylate/acrylic acid (PMMA/AA) were fabricated using a wire coating technique. Poly(acrylic acid) controls the level of MWCNT dispersion in aqueous mixtures and retains the well-dispersed state in the polymer matrix after solidification resulting from extended polymer chains by adjusting the pH value. The exfoliating the MWCNT bundles by extended polymer chains results in the excellent dispersion of MWCNT. It causes a lower surface electrical resistance at the same MWCNT content. The hydrophilic functional groups (-COO( - )NA( + )) also caused a decrease in the crystallization of PMMA and led to an increase in the transmittance.

  17. Eradicating group A streptococcus bacteria and biofilms using functionalised multi-wall carbon nanotubes.

    PubMed

    Levi-Polyachenko, Nicole; Young, Christie; MacNeill, Christopher; Braden, Amy; Argenta, Louis; Reid, Sean

    2014-11-01

    The aim of this study was to demonstrate that multi-wall carbon nanotubes can be functionalised with antibodies to group A streptoccocus (GAS) for targeted photothermal ablation of planktonic and biofilm residing bacteria. Antibodies for GAS were covalently attached to carboxylated multi-wall carbon nanotubes and incubated with either planktonic or biofilm GAS. Bacterium was then exposed to 1.3 W/cm(2) of 800 nm light for 10-120 s, and then serially diluted onto agar plates from which the number of colony forming units was determined. Photothermal ablation of GAS on the surface of full thickness ex vivo porcine skin and histological sectioning were done to examine damage in adjacent tissue. Approximately 14% of the GAS antibody-functionalised nanotubes attached to the bacterium, and this amount was found to be capable of inducing photothermal ablation of GAS upon exposure to 1.3 W/cm(2) of 800 nm light. Cell viability was not decreased upon exposure to nanotubes or infrared light alone. Compared to carboxylated multi-wall carbon nanotubes, antibody-labelled nanotubes enhanced killing in both planktonic and biofilm GAS in conjunction with infrared light. Analysis of GAS photothermally ablated in direct contact with ex vivo porcine skin shows that heat sufficient for killing GAS remains localised and does not cause collateral damage in tissue adjacent to the treated area. The results of this study support the premise that carbon nanotubes may be effectively utilised as highly localised photothermal agents with the potential for translation into the clinical treatment of bacterial infections of soft tissue.

  18. Dispersion and Mechanical Properties of Carbon Nanotube/Polymer Composites via Melt Compounding

    NASA Astrophysics Data System (ADS)

    Gorga, Russell; Cohen, Robert

    2003-03-01

    This work is focused on the fabrication of carbon nanotube/ polymer composites via melt compounding. The main objective of this work is to realize the outstanding properties of carbon nanotubes (high modulus, high thermal and electrical conductivity, elastic buckling) at the macroscopic level by blending carbon nanotubes into a polymer matrix. The challenge lies in dispersing these one dimensional nanoparticles in the polymer matrix. Dispersion of the nanotubes in the composites is analyzed via transmission and scanning electron microscopy. Mechanical properties as well as electrical and thermal conductivity are measured as a function of nanotube loading, orientation, and extrusion conditions. Multi-wall nanotube loadings in the range of 1 and 10 wtconcave-downward departures from the linear stress-strain behavior of the unmodified polymer below 5observations are discussed in the context of possible deformation mechanisms for the nanotube composites.

  19. An evaluation of the impact of multi-walled carbon nanotubes on soil microbial community structure and functional diversity

    USDA-ARS?s Scientific Manuscript database

    Increasing application of carbon nanotubes (CNTs) triggers the need for an assessment of their effects on organisms in the environment. Soil microbial communities play a significant role in soil organic matter dynamics and nutrient cycling. This study evaluated the impacts of multi-walled carbon nan...

  20. Rapid prototyping of three-dimensional microstructures from multiwalled carbon nanotubes

    SciTech Connect

    Hung, W.H.; Kumar, Rajay; Bushmaker, Adam

    The authors report a method for creating three-dimensional carbon nanotube structures, whereby a focused laser beam is used to selectively burn local regions of a dense forest of multiwalled carbon nanotubes. Raman spectroscopy and scanning electron microscopy are used to quantify the threshold for laser burnout and depth of burnout. The minimum power density for burning carbon nanotubes in air is found to be 244 {mu}W/{mu}m{sup 2}. We create various three-dimensional patterns using this method, illustrating its potential use for the rapid prototyping of carbon nanotube microstructures. Undercut profiles, changes in nanotube density, and nanoparticle formation are observed after lasermore » surface treatment and provide insight into the dynamic process of the burnout mechanism.« less

  1. Electrical conductivity and electromagnetic interference shielding of epoxy nanocomposite foams containing functionalized multi-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Jiantong; Zhang, Guangcheng; Zhang, Hongming; Fan, Xun; Zhou, Lisheng; Shang, Zhengyang; Shi, Xuetao

    2018-01-01

    Epoxy/functionalized multi-wall carbon nanotube (EP/F-MWCNT) microcellular foams were fabricated through a supercritical CO2 (scCO2) foaming method. MWCNTs with carboxylation treatment were disentangled by using alpha-zirconium phosphate (ZrP) assisting dispersion method and functionalized with sulfanilamide. The F-MWCNTs were redispersed in acetone for mixing with epoxy resins to prepare nanocomposites. It was found that the dispersion of MWCNTs could be improved, thus heterogeneous nucleation effect of F-MWCNTs took place effectively during the foaming process, resulting in the formation of microcellular structure with larger cell density and smaller cell size. The volume conductivity and electromagnetic interference shielding performance of foamed EP/F-MWCNT nanocomposites were studied. When the F-MWCNT addition was 5 wt%, the conductivity of the foamed EP/F-MWCNT nanocomposites was 3.02 × 10-4 S/cm and the EMI shielding effectiveness (SE) reached 20.5 dB, significantly higher than the corresponding results of nanocomposite counterparts, indicating that introducing microcellular structure in EP/F-MWCNT nanocomposites would beneficial to improve their electrical conductivity and electromagnetic interference shielding performance.

  2. Surface modification of commercial seawater reverse osmosis membranes by grafting of hydrophilic monomer blended with carboxylated multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Vatanpour, Vahid; Zoqi, Naser

    2017-02-01

    In this study, modification of commercial seawater reverse osmosis membranes was carried out with simultaneous use of surface grafting and nanoparticle incorporation. Membrane grafting with a hydrophilic acrylic acid monomer and thermal initiator was used to increase membrane surface hydrophilicity. The used nanomaterial was carboxylated multiwalled carbon nanotubes (MWCNTs), which were dispersed in the grafting solution and deposited on membrane surface to reduce fouling by creating polymer brushes and hydrodynamic resistance. Effectiveness of the grafting process (formation of graft layer on membrane surface) was proved by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses. Increase of membrane surface hydrophilicity was approved with contact angle test. First, the grafting was performed on the membrane surfaces with different monomer concentrations, various contact times and several membrane curing times (three variables for optimization). The modified membranes were tested by a cross-flow setup using saline solution for permeability and rejection tests, and bovine serum albumin (BSA) solution for fouling test. The results showed that the modified membranes with 0.75 M of monomer, 3 min contact time and 80 min curing time in an oven at 50 °C presented the highest flux and lowest rejection decline related to the commercial reverse osmosis membrane. In the next step, the optimum grafting condition was selected and the nanotubes with different weight percentages were dispersed in the acrylic acid monomer solution. The membrane containing 0.25 wt% COOH-MWCNTs showed the highest fouling resistance.

  3. The Study on the Mechanical Properties of Multi-walled Carbon Nanotube/Polypropylene Fibers

    NASA Astrophysics Data System (ADS)

    Youssefi, Mostafa; Safaie, Banafsheh

    2018-06-01

    Polypropylene (PP) is an important semicrystalline polymer with various applications. Polypropylene fibers containing 1 wt% of multi-walled carbon nanotube was spun using a conventional melt spinning apparatus. The produced fibers were drawn with varying levels of draw ratio. The mechanical properties of the composites were studied. Tensile strength and modulus of the composite fibers were increased with the increase in draw ratio. Molecular orientation and helical content of the composite fibers were increased after drawing. To conclude, tensile properties and molecular orientation of the composite fibers were higher than those of neat polypropylene fibers with the same draw ratio.

  4. Breakdown voltage reduction by field emission in multi-walled carbon nanotubes based ionization gas sensor

    SciTech Connect

    Saheed, M. Shuaib M.; Muti Mohamed, Norani; Arif Burhanudin, Zainal, E-mail: zainabh@petronas.com.my

    2014-03-24

    Ionization gas sensors using vertically aligned multi-wall carbon nanotubes (MWCNT) are demonstrated. The sharp tips of the nanotubes generate large non-uniform electric fields at relatively low applied voltage. The enhancement of the electric field results in field emission of electrons that dominates the breakdown mechanism in gas sensor with gap spacing below 14 μm. More than 90% reduction in breakdown voltage is observed for sensors with MWCNT and 7 μm gap spacing. Transition of breakdown mechanism, dominated by avalanche electrons to field emission electrons, as decreasing gap spacing is also observed and discussed.

  5. Coulomb blockade in a single tunnel junction directly connected to a multiwalled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Haruyama, Junji; Takesue, Izumi; Sato, Yuki

    2000-10-01

    We report on Coulomb blockade in a single tunnel junction directly connected to a multiwalled carbon nanotube (MWNT) by utilizing a nanoporous alumina film. The MWNT exhibits a weak localization effect with strong spin flip scattering. Experimental results and analysis suggest that a high-impedance external environment caused by the weak localization in the MWNT can yield Coulomb blockade, in accordance with phase correlation theory in a single junction system. It is also revealed that the Coulomb blockade is very sensitive to phase modulation in the MWNT, which also acts as a high-impedance transmission line.

  6. Immobilization of cross-linked tannase enzyme on multiwalled carbon nanotubes and its catalytic behavior.

    PubMed

    Ong, Chong-Boon; Annuar, Mohamad S M

    2018-02-07

    Immobilization of cross-linked tannase on pristine multiwalled carbon nanotubes (MWCNT) was successfully performed. Cross-linking of tannase molecules was made through glutaraldehyde. The immobilized tannase exhibited significantly improved pH, thermal, and recycling stability. The optimal pH for both free and immobilized tannase was observed at pH 5.0 with optimal operating temperature at 30°C. Moreover, immobilized enzyme retained greater biocatalytic activities upon 10 repeated uses compared to free enzyme in solution. Immobilization of tannase was accomplished by strong hydrophobic interaction most likely between hydrophobic amino acid moieties of the glutaraldehyde-cross-linked tannase to the MWCNT.

  7. Long-term hepatotoxicity of polyethylene-glycol functionalized multi-walled carbon nanotubes in mice

    NASA Astrophysics Data System (ADS)

    Zhang, Danying; Deng, Xiaoyong; Ji, Zongfei; Shen, Xizhong; Dong, Ling; Wu, Minghong; Gu, Taoying; Liu, Yuanfang

    2010-04-01

    The toxicity of polyethylene-glycol functionalized (PEGylated) multi-walled carbon nanotubes (MWCNTs) and non-PEGylated MWCNTs in vivo was evaluated and compared. Mice were exposed to MWCNTs by intravenous injection. The activity level of glutathione, superoxide dismutase and gene expression in liver, as well as some biochemical parameters and the tumor necrosis factor alpha level in blood were measured over 2 months. The pathological and electron micrographic observations of liver evidently indicate that the damage caused by non-PEGylated MWCNTs is slightly more severe than that of PEGylated MWCNTs, which means that PEGylation can partly, but not substantially, improve the in vivo biocompatibility of MWCNTs.

  8. Rheological behaviour, mechanical properties and morphological aspects of thermoplastic polyurethane reinforced with multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Russo, Pietro; Acierno, Domenico; Spena, Paola

    2010-06-01

    Melt blended compounds based on a film grade thermoplastic polyurethane resin filled with relatively low contents of multiwalled carbon nanotubes have been investigated. Materials, prepared through the production of a masterbatch containing 3 wt% of nanotubes and subsequent dilution of the same by addition of matrix pellets, were analyzed in the form of tapes and films always taking the neat matrix, processed in the same conditions, as the reference. Improvements of the matrix extrudability and mechanical benefits showed for all investigated composite samples have been satisfactorily interpreted by morphological observations carried out in both transmission and scanning electron microscopy.

  9. Biofunctionalization of multiwalled carbon nanotubes by electropolymerized poly(pyrrole-concanavalin A) films.

    PubMed

    Papper, Vladislav; Elouarzaki, Kamal; Gorgy, Karine; Sukharaharja, Ayrine; Cosnier, Serge; Marks, Robert S

    2014-10-13

    The synthesis and electropolymerization of a pyrrolic concanavalin A derivative (pyrrole-Con A) onto a multiwalled carbon nanotube (MWCNT) deposit is reported. Glucose oxidase was then immobilized onto the MWCNT-poly(pyrrole-Con A) coating by affinity carbohydrate interactions with the polymerized Con A protein. The resulting enzyme electrode was applied to the amperometric detection of glucose exhibiting a high sensitivity of 36 mA cm(-2) mol(-1) L and a maximum current density of 350 μA cm(-2) . © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Multiwalled carbon nanotubes for drug delivery: Efficiency related to length and incubation time.

    PubMed

    Sciortino, Niccolò; Fedeli, Stefano; Paoli, Paolo; Brandi, Alberto; Chiarugi, Paola; Severi, Mirko; Cicchi, Stefano

    2017-04-15

    Batches of oxidized multiwalled carbon nanotubes differing in length were adopted to prepare two drug delivery systems (DDS) loaded with doxorubicin. The different internalization of the two batches, verified by atomic emission spectroscopy onto cell lysates, was also confirmed by the different toxicity of the same DDS loaded with doxorubicin. In vitro experiments evidenced, after 48h of incubation, the superior efficacy of the shortest nanotubes. However, upon prolonging the incubation time up to 72h the difference in efficiency was minimized due to the spontaneous release of doxorubicin by the non-internalized long nanotubes. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Monolayer formation of human osteoblastic cells on vertically aligned multiwalled carbon nanotube scaffolds.

    PubMed

    Lobo, Anderson O; Antunes, Erica F; Palma, Mariana Bs; Pacheco-Soares, Cristina; Trava-Airoldi, Vladimir J; Corat, Evaldo J

    2010-03-12

    Monolayer formation of SaOS-2 (human osteoblast-like cells) was observed on VACNT (vertically aligned multiwalled carbon nanotubes) scaffolds without purification or functionalization. The VACNT were produced by a microwave plasma chemical vapour deposition on titanium surfaces with nickel or iron as catalyst. Cell viability and morphology studies were evaluated by LDH (lactate dehydrogenase) release assay and SEM (scanning electron microscopy), respectively. The non-toxicity and the flat spreading with monolayer formation of the SaOs-2 on VACNT scaffolds surface indicate that they can be used for biomedical applications.

  12. Highly Conductive Flexible Multi-Walled Carbon Nanotube Sheet Films for Transparent Touch Screen

    NASA Astrophysics Data System (ADS)

    Jung, Daewoong; Lee, Kyung Hwan; Kim, Donghyun; Burk, Dorothea; Overzet, Lawrence J.; Lee, Gil Sik

    2013-03-01

    Highly conductive and transparent thin films were prepared using highly purified multi-walled carbon nanotube (MWCNT) sheets. The electrical properties of the MWCNT sheet were remarkably improved by an acid treatment, resulting in densely packed MWCNTs. The morphology of the sheets reveals that continuous electrical pathways were formed by the acid treatment, greatly improving the sheet resistance all the while maintaining an excellent optical transmittance. These results encourage the use of these MWCNT sheets with low sheet resistance (450 Ω/sq) and high optical transmittance (90%) as a potential candidate for flexible display applications.

  13. Nonlinear tapping dynamics of multi-walled carbon nanotube tipped atomic force microcantilevers

    NASA Astrophysics Data System (ADS)

    Lee, S. I.; Howell, S. W.; Raman, A.; Reifenberger, R.; Nguyen, C. V.; Meyyappan, M.

    2004-05-01

    The nonlinear dynamics of an atomic force microcantilever (AFM) with an attached multi-walled carbon nanotube (MWCNT) tip is investigated experimentally and theoretically. We present the experimental nonlinear frequency response of a MWCNT tipped microcantilever in the tapping mode. Several unusual features in the response distinguish it from those traditionally observed for conventional tips. The MWCNT tipped AFM probe is apparently immune to conventional imaging instabilities related to the coexistence of attractive and repulsive tapping regimes. A theoretical interaction model for the system using an Euler elastica MWCNT model is developed and found to predict several unusual features of the measured nonlinear response.

  14. Control of tunnel barriers in multi-wall carbon nanotubes using focused ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Tomizawa, H.; Suzuki, K.; Yamaguchi, T.; Akita, S.; Ishibashi, K.

    2017-04-01

    We have formed tunnel barriers in individual multi-wall carbon nanotubes using the Ga focused ion beam irradiation. The barrier height was estimated by the temperature dependence of the current (Arrhenius plot) and the current-voltage curves (Fowler-Nordheim plot). It is shown that the barrier height has a strong correlation with the barrier resistance that is controlled by the dose. Possible origins for the variation in observed barrier characteristics are discussed. Finally, the single electron transistor with two barriers is demonstrated.

  15. The Study on the Mechanical Properties of Multi-walled Carbon Nanotube/Polypropylene Fibers

    NASA Astrophysics Data System (ADS)

    Youssefi, Mostafa; Safaie, Banafsheh

    2018-01-01

    Polypropylene (PP) is an important semicrystalline polymer with various applications. Polypropylene fibers containing 1 wt% of multi-walled carbon nanotube was spun using a conventional melt spinning apparatus. The produced fibers were drawn with varying levels of draw ratio. The mechanical properties of the composites were studied. Tensile strength and modulus of the composite fibers were increased with the increase in draw ratio. Molecular orientation and helical content of the composite fibers were increased after drawing. To conclude, tensile properties and molecular orientation of the composite fibers were higher than those of neat polypropylene fibers with the same draw ratio.

  16. Nanoscale welding of multi-walled carbon nanotubes by 1064 nm fiber laser

    NASA Astrophysics Data System (ADS)

    Yuan, Yanping; Liu, Zhi; Zhang, Kaihu; Han, Weina; Chen, Jimin

    2018-07-01

    This study proposes an efficient approach which uses 1064 nm continuous fiber laser to achieve nanoscale welding of crossed multi-walled carbon nanotubes (MWCNTs). By changing the irradiation time, different quality of nanoscale welding is obtained. The morphology changes are investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). The experiments demonstrate that better quality of MWCNTs nanoscale welding after 3 s irradiation can be obtained. It is found that new graphene layers between crossed nanotubes induced by laser make the nanoscale welding achieved due to the absorption of laser energy.

  17. Transport comparison of multiwall carbon nanotubes by contacting outer shell and all shells.

    PubMed

    Luo, Qiang; Cui, A-Juan; Zhang, Yi-Guang; Lu, Chao; Jin, Ai-Zi; Yang, Hai-Fang; Gu, Chang-Zhi

    2010-11-01

    Carbon nanotubes, particularly multiwall carbon nanotubes (MWCNTs) can serve as interconnects in nanoelectronic devices and integrated circuits because of their extremely large current-carrying capacity. Many experimental results about the transport properties of individual MWCNTs by contacting outer shell or all shells have been reported. In this work, a compatible method with integrated circuit manufacturing process was presented to compare the transport property of an individual multiwall carbon nanotube (MWCNT) by contacting outer shell only and all shells successively. First of the Ti/Au electrodes contacting outer shell only were fabricated onto the nanotube through the sequence of electron beam lithography (EBL) patterning, metal deposition and lift-off process. After the characterization of its transport property, focused ion beam (FIB) was used to drill holes through the same nanotube at the as-deposited electrodes. Then new contact to the holes and electrodes were made by ion-induced deposition of tungsten from W(CO)6 precursor gas. The transport results indicated that the new contact to all shells can clear up the intershell resistance and the electrical conductance of the tube can be improved about 8 times compared to that of by contacting outer shell only.

  18. Decorating multi-walled carbon nanotubes with nickel nanoparticles for selective hydrogenation of citral

    SciTech Connect

    Tang Yuechao; Yang Dong; Qin Feng

    The nanocomposites of multi-walled carbon nanotubes (MWNTs) decorated with nickel nanoparticles were conveniently prepared by a chemical reduction of nickel salt in the present of poly(acrylic acid) grafted MWNTs (PAA-g-MWNTs). Due to the strong interaction between Ni{sup 2+} and -COOH, PAA-g-MWNTs became an excellent supporting material for Ni nanoparticles. The morphology and distribution of Ni nanoparticles on the surface of MWNTs were greatly influenced by the reduction temperatures, the experimental results also showed that the distribution of Ni nanoparticles was greatly improved while the MWNTs were modified by poly(acrylic acid) (PAA). The hydrogenation activity and selectivity of MWNTs decorated withmore » Ni nanoparticles (Ni-MWNTs) for alpha, beta-unsaturated aldehyde (citral) were also studied, and the experimental results showed that the citronellal, an important raw material for flavoring and perfumery industries, is the favorable product with a percentage as high as 86.9%, which is 7 times higher than that of catalyst by Ni-supported active carbon (Ni-AC). - Abstract: Nickel nanoparticles decorated multi-walled carbon nanotubes (Ni-MWNTs) nanocomposites were conveniently prepared by a chemical reduction of nickel salt in the present of poly(acrylic acid) grafted MWNTs (PAA-g-MWNTs). These nanocomposites possessed excellent catalytic activity and selectivity for hydrogenation of citral.« less

  19. Removal of heavy metal ions from wastewaters using dendrimer-functionalized multi-walled carbon nanotubes.

    PubMed

    Iannazzo, Daniela; Pistone, Alessandro; Ziccarelli, Ida; Espro, Claudia; Galvagno, Signorino; Giofré, Salvatore V; Romeo, Roberto; Cicero, Nicola; Bua, Giuseppe D; Lanza, Giuseppe; Legnani, Laura; Chiacchio, Maria A

    2017-06-01

    Dendrimer-functionalized multi-walled carbon nanotubes (MWCNT) for heavy metal ion removal from wastewaters were developed. Triazole dendrimers (TD) were built directly onto the carbon nanotube surface by successive click chemistry reactions affording the zero- and first-generation dendrimer-functionalized MWCNT (MWCNT-TD1 and MWCNT-TD2). The Moedritzer-Irani reaction carried out on the amino groups present on the MWCNT-TD2 sample gave the corresponding α-aminophosphonate nanosystem MWCNT-TD2P. Both MWCNT-TD2 and MWCNT-TD2P nanosystems have been characterized by physical, chemical, and morphological analyses. Their chelating abilities towards the toxic metal ions Pb 2+ , Hg 2+ , and Ni 2+ and the harmless Ca 2+ ion have been experimentally evaluated in the two different sets of experiments and at the salt concentrations of 1 mg/mL or 1 μg/mL by inductively coupled plasma mass spectrometry (ICP-MS). The results of these studies pointed out the interesting chelating behavior for the phosphonated nanosystem towards the Hg 2+ ion. The complexation mode of the best chelating system MWCNT-TD2P with mercury was investigated through density functional theory (DFT) calculations, suggesting a chelation mechanism involving the two oxygen atoms of the phosphate group. The synthesized dendrimers, supported on the multi-walled carbon nanotubes, have shown the potential to be used for the selective toxic metal ion removal and recovery.

  20. Controlled Patterning and Growth of Single Wall and Multi-wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Delzeit, Lance D. (Inventor)

    2005-01-01

    Method and system for producing a selected pattern or array of at least one of a single wall nanotube and/or a multi-wall nanotube containing primarily carbon. A substrate is coated with a first layer (optional) of a first selected metal (e.g., Al and/or Ir) and with a second layer of a catalyst (e.g., Fe, Co, Ni and/or Mo), having selected first and second layer thicknesses provided by ion sputtering, arc discharge, laser ablation, evaporation or CVD. The first layer and/or the second layer may be formed in a desired non-uniform pattern, using a mask with suitable aperture(s), to promote growth of carbon nanotubes in a corresponding pattern. A selected heated feed gas (primarily CH4 or C2Hn with n=2 and/or 4) is passed over the coated substrate and forms primarily single wall nanotubes or multiple wall nanotubes, depending upon the selected feed gas and its temperature. Nanofibers, as well as single wall and multi-wall nanotubes, are produced using plasma-aided growth from the second (catalyst) layer. An overcoating of a selected metal or alloy can be deposited, over the second layer, to provide a coating for the carbon nanotubes grown in this manner.

  1. Strain and Temperature Sensing Properties of Multiwalled Carbon Nanotube Yarn Composites

    NASA Technical Reports Server (NTRS)

    Kahng, Seun K.; Gates, Thomas S.; Jefferson, Gail D.

    2008-01-01

    Strain and temperature response of Multiwalled Carbon Nanotube (MWCNT/CNT) yarns on a stainless steel test beam has been studied. The carbon nanotube yarns are spun from a multiwalled carbon nanotube forest grown on a silicon substrate to a 4-ply yarn with a diameter of about 15-20 microns. Four of the 4-ply CNT yarns are arranged in a Wheatstone bridge configuration on the stainless steel test beam using a thin layer of polyurethane resin that insulates and protects the yarns from the test beam. Strain sensitivities of the CNT yarn sensors range from 1.39 to 1.75 mV/V/1000 microstrain at room temperature, and temperature sensitivity of the CNT yarn bridge is 91 microA/degC. Resistance of the yarns range from 215 to 270 ohms for CNT yarn length of approximately 5 mm. Processes used in attaching the CNT yarns on the test beam and experimental procedures used for the measurements are described. Conventional metallic foil strain gages are attached to the test beam to compare with the CNT sensors. The study demonstrates multifunctional capability of the sensor for strain and temperature measurements and shows its applicability where engineering strain is less than 3%.

  2. Effects of multi-walled carbon nanotube materials on Ruditapes philippinarum under climate change: The case of salinity shifts.

    PubMed

    De Marchi, Lucia; Neto, Victor; Pretti, Carlo; Figueira, Etelvina; Chiellini, Federica; Morelli, Andrea; Soares, Amadeu M V M; Freitas, Rosa

    2018-06-01

    The toxicity of carbon nanotubes (CNTs) is closely related to their physico-chemical characteristics as well as the physico-chemical parameters of the media where CNTs are dispersed. In a climate change scenario, changes in seawater salinity are becoming a topic of concern particularly in estuarine and coastal areas. Nevertheless, to our knowledge no information is available on how salinity shifts may alter the sensitivity (in terms of biochemical responses) of bivalves when exposed to different CNTs. For this reason, a laboratory experiment was performed exposing the Manila clam Ruditapes philippinarum, one of the most dominant bivalves of the estuarine and coastal lagoon environments, for 28 days to unfunctionalized multi-walled carbon nanotube MWCNTs (Nf-MWCNTs) and carboxylated MWCNTs (f-MWCNTs), maintained at control salinity (28) and low salinity 21. Concentration-dependent toxicity was demonstrated in individuals exposed to both MWCNT materials and under both salinities, generating alterations of energy reserves and metabolism, oxidative status and neurotoxicity compared to non-contaminated clams. Moreover, our results showed greater toxic impacts induced in clams exposed to f-MWCNTs compared to Nf-MWCNTs. In the present study it was also demonstrated how salinity shifts altered the toxicity of both MWCNT materials as well as the sensitivity of R. philippinarum exposed to these contaminates in terms of clam metabolism, oxidative status and neurotoxicity. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Preparation of micelle supported magnetic hydroxylated multi-walled carbon nanotubes based DSPE for determination of PAHs

    NASA Astrophysics Data System (ADS)

    Wang, Mingyu; Zhang, Shaojun; Zhang, Xiao; Li, Deyu

    2017-06-01

    A micelle supported Fe3O4 magnetic nanoparticles decorated hydroxylated multi-walled carbon nanotubes material was synthesized. The material was facilely synthesized between carbon nanotubes and Fe2+. The synthesized nanomaterial served as an excellent support for micelles, exhibiting high loading capacity and selectivity. The prepared material used in dispersive solid-phase extraction (DSPE) for investigation of gaseous phase polycyclic aromatic hydrocarbons (PAHs) emitted from marine diesel engine for the first time. The application showed good response (R2 > 0.9981) in the range of 0.02 - 1.0 μg/L, satisfactory reproducibility (variation less than ± 10%) and high precision. Limits of detection of sixteen PAHs ranged from 0.009 to 0.018 μg/L (S/N=3). The spiked recovery of proposed method (72.65-96.54 %) was 1.01 - 2.32 times higher than that of the conventional method. The enrichment factors reached to 39.65-121.32 that exhibited good enrichment ability.

  4. Comparative Studies on Al-Based Composite Powder Reinforced with Nano Garnet and Multi-wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Basariya, M. Raviathul; Srivastava, V. C.; Mukhopadhyay, N. K.

    2015-11-01

    Effect of mechanical alloying/milling on microstructural evolution and hardness variations of garnet and multi-walled carbon nanotubes (MWCNTs)-reinforced Al-Mg-Si alloy (EN AW6082) composites are investigated. Structural and morphological studies revealed that the composite powders prepared by milling display a more homogenous distribution of the reinforcing particles. Improved nanoindentation hardness viz., 4.24 and 5.90 GPa are achieved for EN AW6082/Garnet and EN AW6082/MWCNTs composites, respectively, and it is attributed to severe deformation of the aluminum alloy powders and embedding of the harder reinforcement particles uniformly into the aluminum alloy matrix. However, enhancement in case of MWCNTs-reinforced composite makes apparent the effect of its nanosized uniform dispersion in the matrix, thereby resisting the plastic deformation at lower stress and increased dislocation density evolved during high-energy ball milling. The results of the present study indicate that carbon nanotubes and garnet can be effectively used as reinforcements for Al-based composites.

  5. Comparative inhalation toxicity of multi-wall carbon nanotubes, graphene, graphite nanoplatelets and low surface carbon black

    PubMed Central

    2013-01-01

    Background Carbon nanotubes, graphene, graphite nanoplatelets and carbon black are seemingly chemically identical carbon-based nano-materials with broad technological applications. Carbon nanotubes and carbon black possess different inhalation toxicities, whereas little is known about graphene and graphite nanoplatelets. Methods In order to compare the inhalation toxicity of the mentioned carbon-based nanomaterials, male Wistar rats were exposed head-nose to atmospheres of the respective materials for 6 hours per day on 5 consecutive days. Target concentrations were 0.1, 0.5, or 2.5 mg/m3 for multi-wall carbon nanotubes and 0.5, 2.5, or 10 mg/m3 for graphene, graphite nanoplatelets and low-surface carbon black. Toxicity was determined after end of exposure and after three-week recovery using broncho-alveolar lavage fluid and microscopic examinations of the entire respiratory tract. Results No adverse effects were observed after inhalation exposure to 10 mg/m3 graphite nanoplatelets or relatively low specific surface area carbon black. Increases of lavage markers indicative for inflammatory processes started at exposure concentration of 0.5 mg/m3 for multi-wall carbon nanotubes and 10 mg/m3 for graphene. Consistent with the changes in lavage fluid, microgranulomas were observed at 2.5 mg/m3 multi-wall carbon nanotubes and 10 mg/m3 graphene. In order to evaluate volumetric loading of the lung as the key parameter driving the toxicity, deposited particle volume was calculated, taking into account different methods to determine the agglomerate density. However, the calculated volumetric load did not correlate to the toxicity, nor did the particle surface burden of the lung. Conclusions The inhalation toxicity of the investigated carbon-based materials is likely to be a complex interaction of several parameters. Until the properties which govern the toxicity are identified, testing by short-term inhalation is the best option to identify hazardous properties in

  6. Comparative inhalation toxicity of multi-wall carbon nanotubes, graphene, graphite nanoplatelets and low surface carbon black.

    PubMed

    Ma-Hock, Lan; Strauss, Volker; Treumann, Silke; Küttler, Karin; Wohlleben, Wendel; Hofmann, Thomas; Gröters, Sibylle; Wiench, Karin; van Ravenzwaay, Bennard; Landsiedel, Robert

    2013-06-17

    Carbon nanotubes, graphene, graphite nanoplatelets and carbon black are seemingly chemically identical carbon-based nano-materials with broad technological applications. Carbon nanotubes and carbon black possess different inhalation toxicities, whereas little is known about graphene and graphite nanoplatelets. In order to compare the inhalation toxicity of the mentioned carbon-based nanomaterials, male Wistar rats were exposed head-nose to atmospheres of the respective materials for 6 hours per day on 5 consecutive days. Target concentrations were 0.1, 0.5, or 2.5 mg/m3 for multi-wall carbon nanotubes and 0.5, 2.5, or 10 mg/m3 for graphene, graphite nanoplatelets and low-surface carbon black. Toxicity was determined after end of exposure and after three-week recovery using broncho-alveolar lavage fluid and microscopic examinations of the entire respiratory tract. No adverse effects were observed after inhalation exposure to 10 mg/m3 graphite nanoplatelets or relatively low specific surface area carbon black. Increases of lavage markers indicative for inflammatory processes started at exposure concentration of 0.5 mg/m3 for multi-wall carbon nanotubes and 10 mg/m3 for graphene. Consistent with the changes in lavage fluid, microgranulomas were observed at 2.5 mg/m3 multi-wall carbon nanotubes and 10 mg/m3 graphene. In order to evaluate volumetric loading of the lung as the key parameter driving the toxicity, deposited particle volume was calculated, taking into account different methods to determine the agglomerate density. However, the calculated volumetric load did not correlate to the toxicity, nor did the particle surface burden of the lung. The inhalation toxicity of the investigated carbon-based materials is likely to be a complex interaction of several parameters. Until the properties which govern the toxicity are identified, testing by short-term inhalation is the best option to identify hazardous properties in order to avoid unsafe applications or select

  7. Facile Synthesis of Highly Aligned Multiwalled Carbon Nanotubes from Polymer Precursors

    DOE PAGES

    Han, Catherine Y.; Xiao, Zhi-Li; Wang, H. Hau; ...

    2009-01-01

    We report a facile one-step approach which involves no flammable gas, no catalyst, and no in situ polymerization for the preparation of well-aligned carbon nanotube array. A polymer precursor is placed on top of an anodized aluminum oxide (AAO) membrane containing regular nanopore arrays, and slow heating under Ar flow allows the molten polymer to wet the template through adhesive force. The polymer spread into the nanopores of the template to form polymer nanotubes. Upon carbonization the resulting multi-walled carbon nanotubes duplicate the nanopores morphology precisely. The process is demonstrated for 230, 50, and 20 nm pore membranes. The synthesized carbonmore » nanotubes are characterized with scanning/transmission electron microscopies, Raman spectroscopy, and resistive measurements. Convenient functionalization of the nanotubes with this method is demonstrated through premixing CoPt nanoparticles in the polymer precursors.« less

  8. Electrochemical selective detection of dopamine on microbial carbohydrate-doped multiwall carbon nanotube-modified electrodes.

    PubMed

    Jin, Joon-Hyung; Cho, Eunae; Jung, Seunho

    2010-03-01

    Microbial carbohydrate-doped multiwall carbon nanotube (MWNT)-modified electrodes were prepared for the purpose of determining if 4-(2-aminoethyl)benzene-1,2-diol (3,4-dihydroxyphenylalanine; dopamine) exists in the presence of 0.5 mM ascorbic acid, a representative interfering agent in neurotransmitter detection. The microbial carbohydrate dopants were alpha-cyclosophorohexadecaose (alpha-C16) from Xanthomonas oryzae and cyclic-(1 --> 2)-beta-d-glucan (Cys) from Rhizobium meliloti. The cyclic voltammetric responses showed that the highest sensitivity (5.8 x 10(-3) mA cm(-2) microM(-1)) is attained with the Cys-doped MWNT-modified ultra-trace carbon electrode, and that the alpha-C16-doped MWNT-modified glassy carbon electrode displays the best selectivity to dopamine (the approximate peak potential separation is 310 mV).

  9. Ecotoxicological effects of carbofuran and oxidised multiwalled carbon nanotubes on the freshwater fish Nile tilapia: nanotubes enhance pesticide ecotoxicity.

    PubMed

    Campos-Garcia, Janaína; Martinez, Diego Stéfani T; Alves, Oswaldo L; Leonardo, Antônio Fernando Gervásio; Barbieri, Edison

    2015-01-01

    The interactions of carbon nanotubes with pesticides, such as carbofuran, classical contaminants (e.g., pesticides, polyaromatic hydrocarbons, heavy metals, and dyes) and emerging contaminants, including endocrine disruptors, are critical components of the environmental risks of this important class of carbon-based nanomaterials. In this work, we studied the modulation of acute carbofuran toxicity to the freshwater fish Nile tilapia (Oreochromis niloticus) by nitric acid treated multiwalled carbon nanotubes, termed HNO3-MWCNT. Nitric acid oxidation is a common chemical method employed for the purification, functionalisation and aqueous dispersion of carbon nanotubes. HNO3-MWCNT were not toxic to Nile tilapia at concentrations ranging from 0.1 to 3.0 mg/L for exposure times of up to 96 h. After 24, 48, 72 and 96 h, the LC50 values of carbofuran were 4.0, 3.2, 3.0 and 2.4 mg/mL, respectively. To evaluate the influence of carbofuran-nanotube interactions on ecotoxicity, we exposed the Nile tilapia to different concentrations of carbofuran mixed together with a non-toxic concentration of HNO3-MWCNT (1.0 mg/L). After 24, 48, 72, and 96 h of exposure, the LC50 values of carbofuran plus nanotubes were 3.7, 1.6, 0.7 and 0.5 mg/L, respectively. These results demonstrate that HNO3-MWCNT potentiate the acute toxicity of carbofuran, leading to a more than five-fold increase in the LC50 values. Furthermore, the exposure of Nile tilapia to carbofuran plus nanotubes led to decreases in both oxygen consumption and swimming capacity compared to the control. These findings indicate that carbon nanotubes could act as pesticide carriers affecting fish survival, metabolism and behaviour. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. The Influence of Multiwalled Carbon Nanotubes on Polycyclic Aromatic Hydrocarbon (PAH) Bioavailability and Toxicity to Soil Microbial Communities in Alfalfa Rhizosphere

    USDA-ARS?s Scientific Manuscript database

    Carbon nanotubes (CNTs) may affect bioavailability and toxicity of organic contaminants due to their adsorption properties. Recent studies have observed the influence of multiwalled carbon nanotubes (MWNTs) on the fate of polycyclic aromatic hydrocarbons (PAHs) and other organic contaminants. Greenh...

  11. Marine fouling release silicone/carbon nanotube nanocomposite coatings: on the importance of the nanotube dispersion state.

    PubMed

    Beigbeder, Alexandre; Mincheva, Rosica; Pettitt, Michala E; Callow, Maureen E; Callow, James A; Claes, Michael; Dubois, Philippe

    2010-05-01

    The present work reports on the influence of the dispersion quality of multiwall carbon nanotubes (MWCNTs) in a silicone matrix on the marine fouling-release performance of the resulting nanocomposite coatings. A first set of coatings filled with different nanofiller contents was prepared by the dilution of a silicone/MWCNTs masterbatch within a hydrosilylation-curing polydimethylsiloxane resin. The fouling-release properties of the nanocomposite coatings were studied through laboratory assays with the marine alga (seaweed) Ulva, a common fouling species. As reported previously (see Ref. [19]), the addition of a small (0.05%) amount of carbon nanotubes substantially improves the fouling-release properties of the silicone matrix. This paper shows that this improvement is dependent on the amount of filler, with a maximum obtained with 0.1 wt% of multiwall carbon nanotubes (MWCNTs). The method of dispersion of carbon nanotubes in the silicone matrix is also shown to significantly (p = 0.05) influence the fouling-release properties of the coatings. Dispersing 0.1% MWCNTs using the masterbatch approach yielded coatings with circa 40% improved fouling-release properties over those where MWCNTs were dispersed directly in the polymeric matrix. This improvement is directly related to the state of nanofiller dispersion within the cross-linked silicone coating.

  12. Effect of the cesium and potassium doping of multiwalled carbon nanotubes grown in an electrical arc on their emission characteristics

    NASA Astrophysics Data System (ADS)

    Izrael'yants, K. R.; Orlov, A. P.; Ormont, A. B.; Chirkova, E. G.

    2017-04-01

    The effect of cesium and potassium atoms deposited onto multiwalled carbon nanotubes grown in an electrical arc on their emission characteristics was studied. The current-voltage characteristics of the field electron emission of specimens with cesium or potassium doped multiwalled carbon nanotubes of this type were revealed to retain their linear character in the Fowler-Nordheim coordinates within several orders of magnitude of change in the emission current. The deposition of cesium and potassium atoms was shown to lead to a considerable increase in the emission current and a decrease in the work function φ of studied emitters with multiwalled nanotubes. The work function was established to decrease to φ 3.1 eV at an optimal thickness of coating with cesium atoms and to φ 2.9 eV in the case of doping with potassium atoms. Cesium and potassium deposition conditions optimal for the attainment of a maximum emission current were found.

  13. Application of multiwalled carbon nanotubes and its magnetite derivative for emulsified oil removal from produced water.

    PubMed

    Ibrahim, Taleb H; Sabri, Muhammad A; Khamis, Mustafa I

    2018-05-10

    Multiwalled carbon nanotubes and their magnetite derivatives were employed as adsorbents for emulsified oil removal from produced water. The experimental parameters for maximum emulsified oil removal efficiency and effective regeneration of these adsorbents were determined. The optimum parameters in terms of adsorbent dosage, contact time, salinity, pH and temperature were 3.0 g/L, 20.0 min, 0 ppm, 7.0 and 25°C for both adsorbents. Due to their low density, multiwalledcarbon nanotubes could not be successfully employed in packed bed columns. The magnetite derivative has a larger density and hence, for the removal of emulsified oil from produced water packed bed column studies were performed utilizing multiwalled carbon magnetite nanotubes. The packed bed column efficiency and behaviour were evaluated using Thomas, Clark, Yan et al. and Bohart and Adams models. The Yan model was found to best describe the column experimental data. The adsorbents were regenerated using n-hexane and reused several times for oil removal from produced water without any significant decrease in their initial adsorption capacities.

  14. The effect of calcination on multi-walled carbon nanotubes produced by dc-arc discharge.

    PubMed

    Pillai, Sreejarani K; Augustyn, Willem G; Rossouw, Margaretha H; McCrindle, Robert I

    2008-07-01

    Multi-walled carbon nanotubes were synthesized by dc-arc discharge in helium atmosphere and the effect of calcination at different temperatures ranging from 300-600 degrees C was studied in detail. The degree of degradation to the structural integrity of the multi-walled carbon nanotubes during the thermal process was studied by Raman spectroscopy, Scanning electron microscopy and High resolution transmission electron microscopy. The thermal behaviour of the as prepared and calcined samples was investigated by thermogravimetric analysis. Calcination in air at 400 degrees C for 2 hours was found to be an efficient and simple method to eliminate carbonaceous impurities from the nanotube bundles with minimal damage to the tube walls and length. The impurities were oxidized at a faster rate when compared to the nanotubes and gave good yield of about 50%. The nanotubes were observed to be damaged at temperature higher than 450 degrees C. The results show that this method is less destructive when compared liquid phase oxidation with 5 M HNO3.

  15. Electrical transport via variable range hopping in an individual multi-wall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Husain Khan, Zishan; Husain, M.; Perng, T. P.; Salah, Numan; Habib, Sami

    2008-11-01

    E-beam lithography is used to make four leads on an individual multi-wall carbon nanotube for carrying out electrical transport measurements. Temperature dependence of conductance of an individual multi-wall carbon nanotube (MWNT) is studied over a temperature range of (297 4.8 K). The results indicate that the conduction is governed by variable range hopping (VRH) for the entire temperature range (297 4.8 K). This VRH mechanism changes from three dimensions (3D) to two dimensions (2D) as we go down to 70 K. Three-dimensional variable range hopping (3D VRH) is responsible for conduction in the temperature range (297 70 K), which changes to two-dimensional VRH for much lower temperatures (70 4.8 K). For 3D VRH, various Mott parameters such as density of states, hopping distance and hopping energy have been calculated. The 2D VRH mechanism has been applied for the temperature range (70 4.8 K) and, with the help of this model, the parameters such as localization length and hopping distance are calculated. All these parameters give interesting information about this complex structure, which may be useful for many applications.

  16. Carbon dots-decorated multiwalled carbon nanotubes nanocomposites as a high-performance electrochemical sensor for detection of H2O2 in living cells.

    PubMed

    Bai, Jing; Sun, Chunhe; Jiang, Xiue

    2016-07-01

    A novel enzyme-free hydrogen peroxide sensor composed of carbon dots (CDs) and multi-walled carbon nanotubes (MWCNTs) was prepared. It was found that the carbon dots-decorated multi-walled carbon nanotubes nanocomposites (CDs/MWCNTs) modified glassy carbon (GC) electrode (CDs/MWCNTs/GCE) exhibited a significant synergistic electrocatalytic activity towards hydrogen peroxide reduction as compared to carbon dots or multi-walled carbon nanotubes alone, and the CDs/MWCNTs/GCE has shown a low detection limit as well as excellent stability, selectivity, and reproducibility. These remarkable analytical advantages enable the practical application of CDs/MWCNTs/GCE for the real-time tracking of hydrogen peroxide (H2O2) released from human cervical cancer cells with satisfactory results. The enhanced electrochemical activity can be assigned to the edge plane-like defective sites and lattice oxygen in the CDs/MWCNTs nanocomposites due to the small amount of decoration of carbon dots on the multi-walled carbon nanotubes. Based on a facile preparation method and with good electrochemical properties, the CDs/MWCNTs nanocomposites represent a new class of carbon electrode for electrochemical sensor applications. Graphical Abstract CDs/MWCNTs exhibited good electrocatalytic activity and stability to H2O2 reduction and can be used for real-time detection of H2O2 released from living cells.

  17. Amino acid-functionalized multi-walled carbon nanotubes for improving compatibility with chiral poly(amide-ester-imide) containing L-phenylalanine and L-tyrosine linkages

    NASA Astrophysics Data System (ADS)

    Abdolmaleki, Amir; Mallakpour, Shadpour; Borandeh, Sedigheh

    2013-12-01

    Amino acid functionalized multi-walled carbon nanotubes (f-MWCNTs)/poly(amide-ester-imide) (PAEI) composites were fabricated by solution mixing method. Proper functionalization and mixing strategy of MWCNTs provides the best opportunity for better distribution and bonding of nanoparticles to the polymer matrix. MWCNTs have been chemically modified with L-phenylalanine to improve their compatibility with L-phenylalanine based PAEI. Field emission scanning electron microscopy micrographs of composite revealed that f-MWCNTs made a good interaction with polymer chains by wrapping the polymer around them, and transmission electron microscopy results confirmed well dispersion with nano size of f-MWCNTs in the polymer matrix. In addition, thermal analysis showed good enhancement in thermal properties of composites compared to pure polymer. Thermal stability of the composites containing f-MWCNTs was enhanced due to their good dispersion and improved interfacial interaction between the amino acid based PAEI matrix and f-MWCNTs.

  18. Facile and one-pot synthesis of uniform PtRu nanoparticles on polydopamine-modified multiwalled carbon nanotubes for direct methanol fuel cell application.

    PubMed

    Chen, Fengxia; Ren, Junkai; He, Qian; Liu, Jun; Song, Rui

    2017-07-01

    A facile, environment-friendly and one-pot synthesis method for the preparation of high performance PtRu electrocatalysts on the multiwalled carbon nanotubes (MWCNTs) is reported. Herein, bimetallic PtRu electrocatalysts are deposited onto polydopamine (Pdop) - functionalized MWCNTs by mildly stirring at room temperature. Without the use of expensive chemicals or corrosive acids, this noncovalent functionalization of MWCNTs by Pdop is simple, facile and eco-friendly, and thus preserving the integrity and electronic structure of MWCNTs. Due to the well improved dispersion and the decreased size of alloy nanoparticles, the PtRu electrocatalysts on Pdop-functionalized MWCNTs show much better dispersion, higher electrochemically active surface area, and higher electrocatalytic activity for the electrooxidation of methanol in direct methanol fuel cells, compared with the conventional acid-treated MWCNTs. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Electrochemical synthesis of gold nanoparticles on the surface of multi-walled carbon nanotubes with glassy carbon electrode and their application

    NASA Astrophysics Data System (ADS)

    Song, Y. Z.; Li, X.; Song, Y.; Cheng, Z. P.; Zhong, H.; Xu, J. M.; Lu, J. S.; Wei, C. G.; Zhu, A. F.; Wu, F. Y.; Xu, J.

    2013-01-01

    Gold nanoparticles on the surface of multi-walled carbon nanotubes with glassy carbon electrode were prepared using electrochemical synthesis method. The thin films of gold Nanoparticles/multi-walled carbon nanotubes were characterized by scanning electron microscopy, powder X-ray diffraction, and cyclic voltammetry. Electrochemical behavior of adrenaline hydrochloride at gold nanoparticles/multi-walled carbon nanotube modified glassy carbon electrode was investigated. A simple, sensitive, and inexpensive method for determination of adrenaline hydrochloride was proposed.

  20. Synthesis of gold nanoparticles on multi-walled carbon nanotubes (Au-MWCNTs) via deposition precipitation method

    NASA Astrophysics Data System (ADS)

    Zulikifli, Farah Wahida Ahmad; Yazid, Hanani; Halim, Muhammad Zikri Budiman Abdul; Jani, Abdul Mutalib Md

    2017-09-01

    Carbon nanotubes (CNTs) have received impressive consideration as support materials of noble metal catalysts in heterogeneous catalysis due to their good mechanical strength, large surface area and good durability under harsh conditions. The interaction between CNTs and noble metal nanoparticles (NPs) gives an unusual unique microstructure properties and or modification of the electron density of the noble metal clusters, and enhances the catalytic activity. In this study, the MWCNTs were first treated with a mixture of concentrated sulfuric and nitric acid by sonication to improve its dispersibility and to introduce the carboxylic (-COOH) groups on CNTs surfaces. Gold nanoparticles (Au NPs) on multiwalled carbon nanotubes (MWCNTs) were synthesized by the deposition precipitation (DP) method as this method is simpler, low cost, and excellent method. Then, the effect of reducing agent (NaBH4) on gold distribution on the support of MWCNTs was also studied. Dispersion test, Fourier Transform Infrared spectroscopy (FTIR) and Field Emission Scanning Electron Microscope (FESEM) are all used to characterize the functionalized MWCNTs (fCNTs) and the Au NPs-fCNTs catalyst. There are three important peaks in functionalized MWCNTs which correspond to C=O, O-H, and C-O absorption peaks, as a result of the oxidation of COOH groups on the surface of CNTs. The absorption band at 1717 cm-1 is corresponded to C=O stretching of COOH, while the absorption bands at 3384 cm-1 and 1011cm-1 are associated with O-H bending and C-O stretching, respectively. Surface morphology of Au NPs-fCNTs R4 and Au NPs- fCNTs WR catalyst by FESEM showed that the Au NPs of 19.22 ± 2.33 nm and 23.05 ± 2.57 nm size were successfully deposited on CNTs, respectively.

  1. On-chip purification via liquid immersion of arc-discharge synthesized multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hokkanen, Matti J.; Lautala, Saara; Shao, Dongkai; Turpeinen, Tuomas; Koivistoinen, Juha; Ahlskog, Markus

    2016-07-01

    Arc-discharge synthesized multiwalled carbon nanotubes (AD-MWNT) have been proven to be of high quality, but their use is very limited due to difficulties in obtaining them in a clean and undamaged form. Here, we present a simple method that purifies raw AD-MWNT material in laboratory scale without damage, and that in principle can be scaled up. The method consists of depositing raw AD-MWNT material on a flat substrate and immersing the substrate slowly in water, whereby the surface tension force of the liquid-substrate contact line selectively sweeps away the larger amorphous carbon debris and leaves relatively clean MWNTs on the substrate. We demonstrate the utility of the method by preparing clean individual MWNTs for measurement of their Raman spectra. The spectra exhibit the characteristics of high-quality tubes free from contaminants. We also show how one concomitantly with the purification process can obtain large numbers of clean suspended MWNTs.

  2. Effect of porosity variation on the electrochemical behavior of vertically aligned multi-walled carbon nanotubes.

    PubMed

    Raut, Akshay S; Parker, Charles B; Stoner, Brian R; Glass, Jeffrey T

    2012-06-01

    Electrochemical charge storage characteristics of vertically aligned multi-walled carbon nanotubes (MWCNTs) as a function of varying diameter and spacing are reported. It was observed that the specific capacitance of the MWCNTs increased as both diameter and inter-tube spacing decreased. The MWCNT films with 229 nm inter-MWCNT spacing exhibited specific capacitance of 228 F/g versus 70 F/g for 506 nm spacing, when tested in a non-aqueous electrolyte. Further, a trend in specific capacitance versus pore size is proposed. Coupled with previously reported trends observed in the sub-10 nm pore size regime, this is expected to offer better understanding of electrochemical behavior of porous carbon materials over a wide range of pore sizes.

  3. Elastic Response and Failure Studies of Multi-Wall Carbon Nanotube Twisted Yarns

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.; Jefferson, Gail D.; Frankland, Sarah-Jane V.

    2007-01-01

    Experimental data on the stress-strain behavior of a polymer multiwall carbon nanotube (MWCNT) yarn composite are used to motivate an initial study in multi-scale modeling of strength and stiffness. Atomistic and continuum length scale modeling methods are outlined to illustrate the range of parameters required to accurately model behavior. The carbon nanotubes yarns are four-ply, twisted, and combined with an elastomer to form a single-layer, unidirectional composite. Due to this textile structure, the yarn is a complicated system of unique geometric relationships subjected to combined loads. Experimental data illustrate the local failure modes induced by static, tensile tests. Key structure-property relationships are highlighted at each length scale indicating opportunities for parametric studies to assist the selection of advantageous material development and manufacturing methods.

  4. Effect of electrode gap on the sensing properties of multiwalled carbon nanotubes based gas sensor

    NASA Astrophysics Data System (ADS)

    Saheed, Mohamed Shuaib Mohamed; Mohamed, Norani Muti; Burhanudin, Zainal Arif

    2016-11-01

    Vertically aligned multiwalled carbon nanotubes (MWCNT) were grown on Si substrate coated with alumina and iron using chemical vapor deposition. Electrode gap of 10, 25 and 50 µm were adopted to determine the effect of varying gap spacing on the sensing properties such as voltage breakdown, sensitivity and selectivity for three gases namely argon, carbon dioxide and ammonia. Argon has the lowest voltage breakdown for every electrode gap. The fabricated MWCNT based gas sensor drastically reduced the voltage breakdown by 89.5% when the electrode spacing is reduced from 50 µm to 10 µm. The reduction is attributed to the high non-uniform electric field between the electrodes caused by the protrusion of nanotips. The sensor shows good sensitivity and selectivity with the ability to detect the gas in the mixture with air provided that the concentration is ≥ 20% where the voltage breakdown will be close to the pure gas.

  5. Voltammetric Determination of Ferulic Acid Using Polypyrrole-Multiwalled Carbon Nanotubes Modified Electrode with Sample Application

    PubMed Central

    Abdel-Hamid, Refat; Newair, Emad F.

    2015-01-01

    A polypyrrole-multiwalled carbon nanotubes modified glassy carbon electrode-based sensor was devised for determination of ferulic acid (FA). The fabricated sensor was prepared electrochemically using cyclic voltammetry (CV) and characterized using CV and scanning electron microscope (SEM). The electrode shows an excellent electrochemical catalytic activity towards FA oxidation. Under optimal conditions, the anodic peak current correlates linearly to the FA concentration throughout the range of 3.32 × 10−6 to 2.59 × 10−5 M with a detection limit of 1.17 × 10−6 M (S/N = 3). The prepared sensor is highly selective towards ferulic acid without the interference of ascorbic acid. The sensor applicability was tested for total content determination of FA in a commercial popcorn sample and showed a robust functionality. PMID:28347090

  6. Chemical splitting of multiwalled carbon nanotubes to enhance electrochemical capacitance for supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Xinlu; Li, Tongtao; Zhang, Xinlin; Zhong, Qineng; Li, Hongyi; Huang, Jiamu

    2014-06-01

    Multiwalled carbon nanotubes (MWCNTs) were chemically split and self-assembled to a flexible porous paper made of graphene oxide nanoribbons (GONRs). The morphology and microstructure of the pristine MWCNTs and GONRs were analyzed by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy. And the specific surface area and porosity structure were measured by N2 adsorption-desorption. The longitudinally split MWCNTs show an enhancement in specific capacitance from 21 F g-1 to 156 F g-1 compared with the pristine counterpart at 0.1 A g-1 in a 6 M KOH aqueous electrolytes. The electrochemical experiments prove that the chemical splitting of MWCNTs will make inner carbon layers opened and exposed to electrochemical double layers, which can effectively improve the electrochemical capacitance for supercapacitors.

  7. Time-domain finite-difference based analysis of induced crosstalk in multiwall carbon nanotube interconnects

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Nehra, Vikas; Kaushik, Brajesh Kumar

    2017-08-01

    Graphene rolled-up cylindrical sheets i.e. carbon nanotubes (CNTs) is one of the finest and emerging research area. This paper presents the investigation of induced crosstalk in coupled on-chip multiwalled carbon nanotube (MWCNT) interconnects using finite-difference analysis (FDA) in time-domain i.e. the finite-difference time-domain (FDTD) method. The exceptional properties of versatile MWCNTs profess their candidacy to replace conventional on-chip copper interconnects. Time delay and crosstalk noise have been evaluated for coupled on-chip MWCNT interconnects. With a decrease in CNT length, the obtained results for an MWCNT shows that transmission performance improves as the number of shells increases. It has been observed that the obtained results using the finite-difference time domain (FDTD) technique shows a very close match with the HSPICE simulated results.

  8. Thermal characteristics of carbon fiber reinforced epoxy containing multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lee, Jin-woo; Park, Soo-Jeong; Kim, Yun-hae; Riichi-Murakami

    2018-06-01

    The material with irregular atomic structures such as polymer material exhibits low thermal conductivity because of the complex structural properties. Even materials with same atomic configurations, thermal conductivity may be different based on their structural properties. It is expected that nanoparticles with conductivity will change non-conductive polymer base materials to electrical conductors, and improve the thermal conductivity even with extremely small filling amount. Nano-composite materials contain nanoparticles with a higher surface ratio which makes the higher interface percentage to the total surface of nanoparticles. Therefore, thermal resistance of the interface becomes a dominating factor determines the effective thermal conductivity in nano-composite materials. Carbon fiber has characteristic of resistance or magnetic induction and Also, Carbon nanotube (CNT) has electronic and thermal property. It can be applied for heating system. These characteristic are used as heating composite. In this research, the exothermic characteristics of Carbon fiber reinforced composite added CNT were evaluated depend on CNT length and particle size. It was found that the CNT dispersed in the resin reduces the resistance between the interfaces due to the decrease in the total resistance of the heating element due to the addition of CNTs. It is expected to improve the life and performance of the carbon fiber composite material as a result of the heating element resulting from this paper.

  9. Effect of Novel Quercetin Titanium Dioxide-Decorated Multi-Walled Carbon Nanotubes Nanocomposite on Bacillus subtilis Biofilm Development

    PubMed Central

    Raie, Diana S.; Mhatre, Eisha; El-Desouki, Doaa S.; Labena, Ahmed; El-Ghannam, Gamal; Farahat, Laila A.; Youssef, Tareq; Fritzsche, Wolfgang; Kovács, Ákos T.

    2018-01-01

    The present work was targeted to design a surface against cell seeding and adhering of bacteria, Bacillus subtilis. A multi-walled carbon nanotube/titanium dioxide nano-power was produced via simple mixing of carbon nanotube and titanium dioxide nanoparticles during the sol-gel process followed by heat treatment. Successfully, quercetin was immobilized on the nanocomposite via physical adsorption to form a quercetin/multi-walled carbon nanotube/titanium dioxide nanocomposite. The adhesion of bacteria on the coated-slides was verified after 24 h using confocal laser-scanning microscopy. Results indicated that the quercetin/multi-walled carbon nanotube/titanium dioxide nanocomposite had more negativity and higher recovery by glass surfaces than its counterpart. Moreover, coating surfaces with the quercetin-modified nanocomposite lowered both hydrophilicity and surface-attached bacteria compared to surfaces coated with the multi-walled carbon nanotubes/titanium dioxide nanocomposite. PMID:29346268

  10. Co-transport of chlordecone and sulfadiazine in the presence of functionalized multi-walled carbon nanotubes in soils

    USDA-ARS?s Scientific Manuscript database

    Batch and saturated soil column experiments were conducted to investigate sorption and mobility of two 14C-labeled contaminants, the hydrophobic chlordecone (CLD) and the readily water-soluble sulfadiazine (SDZ), in the absence or presence of functionalized multi-walled carbon nanotubes (MWCNTs). Th...

  11. ZnO Functionalization of Multi-walled Carbon Nanotubes for Methane Sensing at Single Parts Per Million Concentration Levels

    EPA Science Inventory

    This paper presents a novel atomic layer deposition (ALD) based ZnO functionalization of surface pre-treated multi-walled carbon nanotubes (MWCNTs) for highly sensitive methane chemoresistive sensors. The temperature optimization of the ALD process leads to enhanced ZnO nanopart...

  12. 40 CFR 721.10277 - Single-walled and multi-walled carbon nanotubes (generic) (P-10-40).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10277 Single-walled and multi-walled carbon nanotubes (generic) (P-10-40). (a) Chemical substance and significant new uses subject to reporting. (1) The...

  13. 40 CFR 721.10266 - Multi-walled carbon nanotubes (generic) (P-08-733 and P-08-734).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10266 Multi-walled carbon nanotubes (generic) (P-08-733 and P-08-734). (a) Chemical substances and significant new uses subject to reporting. (1) The...

  14. 40 CFR 721.10266 - Multi-walled carbon nanotubes (generic) (P-08-733 and P-08-734).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10266 Multi-walled carbon nanotubes (generic) (P-08-733 and P-08-734). (a) Chemical substances and significant new uses subject to reporting. (1) The...

  15. 40 CFR 721.10277 - Single-walled and multi-walled carbon nanotubes (generic) (P-10-40).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10277 Single-walled and multi-walled carbon nanotubes (generic) (P-10-40). (a) Chemical substance and significant new uses subject to reporting. (1) The...

  16. Effect of Acid and Alcohol Network Forces within Functionalized Multiwall Carbon Nanotubes Bundles on Adsorption of Copper (II) Species

    EPA Science Inventory

    Adsorption of metals on carbon nanotubes (CNTs) has important applications in sensors, membranes, and water treatment. The adsorptive capacity of multiwall CNTs for copper species in water depends on the type of functional group present on their surface. The alcohol (COOH) and ac...

  17. Initial Studies of the Bidirectional Reflectance Distribution Function of Multi-Walled Carbon Nanotube Structures for Stray Light Control Applications

    NASA Technical Reports Server (NTRS)

    Butler, J. J.; Tveekrem, J. L.; Quijada, M. A.; Getty, S. A.; Hagopian, J. G.; Georglev, G. T.

    2010-01-01

    The presentation examines the application of low reflectance surfaces in optical instruments, multi-walled carbon nanotubes (MWCNTs), research objects, MWCNT samples, measurement of 8 deg. directional/hemispherical reflectance, measurement of bidirectional reflectance distribution function (BRDF), and what is current the "blackest ever black".

  18. Do goethite surfaces really control the transport and retention of multi-walled carbon nanotubes in chemically heterogeneous porous media?

    USDA-ARS?s Scientific Manuscript database

    Transport and retention behavior of multiwalled carbon nanotubes (MWCNTs) was studied in mixtures of negatively charged quartz sand (QS) and positively charged goethite-coated sand (GQS) to assess the role of chemical heterogeneity. The linear equilibrium sorption model provided a good description o...

  19. Transport and retention of multi-walled carbon nanotubes in saturated porous media: Effects of input concentration and grain size

    USDA-ARS?s Scientific Manuscript database

    Water-saturated column experiments were conducted to investigate the effect of input concentration (Co) and sand grain size on the transport and retention of low concentrations (1, 0.01, and 0.005 mg L/1) of functionalized 14C-labeled multi-walled carbon nanotubes (MWCNT) under repulsive electrostat...

  20. Nanocomposites of nitrile (NBR) rubber with multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Warasitthinon, Nuthathai

    Nanotechnology offers the promise of creating new materials with enhanced performance. There are different kinds of fillers used in rubber nanocomposites, such as carbon black, silica, carbon fibers, and organoclays. Carbon nanotube reinforced elastomers have potential for improved rubber properties in aggressive environments. The first chapter is an introduction to the literature. The second chapter investigated the incorporation of multi-walled carbon nanotubes (MWCNTs) into rubber matrix for potential use in high temperature applications. The vulcanization kinetics of acrylonitrile butadiene rubber (NBR) reinforced with multi-walled carbon nanotubes was investigated. The vulcanized NBR rubber with different loading percentages of MWCNTs was also compared to NBR reinforced with carbon black N330. The optimum curing time at 170°C (T90) was found to decrease with increasing content of MWCNTs. Increased filler loading of both carbon black and MWCNTs gave higher modulus and strength. The MWCNTs filled materials gave better retention of modulus and tensile strength at high temperatures, but lower strength as compared to the carbon black filled samples. In the third chapter, carbon black (CB, 50phr) content in nitrile rubber (NBR) nanocomposites was partially replaced by multi-walled carbon nanotubes (MWCNTs). NBR/CB/CNTs nanocomposites with varying ratio of CB/CNTs (50/0 phr to 40/10 phr) were formulated via the melt-mixing method using an internal mixer. The reinforcing effect of single filler (CB) and mixture of fillers (CB and CNTs) on the properties of NBR nanocomposites was investigated. The cure kinetics and bound rubber content were analyzed using rheometry and solvent swelling method. In addition, mechanical behavior at both room temperature and high temperature (350°F/ 121°C) were examined. The scorch time and curing time values showed that there was no significant effect on the curing behavior of NBR nanocomposites after the partial replacement of CB with

  1. Aqueous solution dispersement of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Woo (Inventor); Park, Cheol (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

    2011-01-01

    Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group.

  2. MICROWAVE-ASSISTED SYNTHESIS OF CROSSLINKED POLY(VINYL ALCOHOL) NANOCOMPOSITES COMPRISING SINGLE-WALLED CARBON NANOTUBES, MULTI-WALLED CARBON NANOTUBES AND BUCKMINSTERFULLERENE

    EPA Science Inventory

    We report a facile method to accomplish cross-linking reaction of poly (vinyl alcohol) (PVA) with single-wall carbon nanotubes (SWNT), multi-wall carbon nanotubes (MWNT), and Buckminsterfullerene (C-60) using microwave (MW) irradiation. Nanocomposites of PVA cross-linked with SW...

  3. Structural and proactive safety aspects of oxidation debris from multiwalled carbon nanotubes.

    PubMed

    Stéfani, Diego; Paula, Amauri J; Vaz, Boniek G; Silva, Rodrigo A; Andrade, Nádia F; Justo, Giselle Z; Ferreira, Carmen V; Filho, Antonio G Souza; Eberlin, Marcos N; Alves, Oswaldo L

    2011-05-15

    The removal of oxidation debris from the oxidized carbon nanotube surface with a NaOH treatment is a key step for an effective functionalization and quality improvement of the carbon nanotube samples. In this work, we show via infrared spectroscopy and ultrahigh resolution and accuracy mass spectrometry that oxidation debris obtained from HNO(3)-treated multiwalled carbon nanotubes is a complex mixture of highly condensed aromatic oxygenated carbonaceous fragments. We have also evaluated their cytotoxicity by using BALB/c 3T3 mouse fibroblasts and HaCaT human keratinocytes as models. By knowing the negative aspects of dissolved organic carbon (DOC) to the water quality, we have demonstrated the removal of these carbon nanotube residues from the NaOH solution (wastewater) by using aluminium sulphate, which is a standard coagulant agent used in conventional drinking water purification and wastewater treatment plants. Our results contribute to elucidate the structural and proactive safety aspects of oxidation debris from oxidized carbon nanotubes towards a greener nanotechnology. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Comparison of cellular toxicity between multi-walled carbon nanotubes and onion-like shell-shaped carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Kang, Seunghyon; Kim, Ji-Eun; Kim, Daegyu; Woo, Chang Gyu; Pikhitsa, Peter V.; Cho, Myung-Haing; Choi, Mansoo

    2015-09-01

    The cellular toxicity of multi-walled carbon nanotubes (MWCNTs) and onion-like shell-shaped carbon nanoparticles (SCNPs) was investigated by analyzing the comparative cell viability. For the reasonable comparison, physicochemical characteristics were controlled thoroughly such as crystallinity, carbon bonding characteristic, hydrodynamic diameter, and metal contents of the particles. To understand relation between cellular toxicity of the particles and generation of reactive oxygen species (ROS), we measured unpaired singlet electrons of the particles and intracellular ROS, and analyzed cellular toxicity with/without the antioxidant N-acetylcysteine (NAC). Regardless of the presence of NAC, the cellular toxicity of SCNPs was found to be lower than that of MWCNTs. Since both particles show similar crystallinity, hydrodynamic size, and Raman signal with negligible contribution of remnant metal particles, the difference in cell viability would be ascribed to the difference in morphology, i.e., spherical shape (aspect ratio of one) for SCNP and elongated shape (high aspect ratio) for MWCNT.

  5. Metal Decorated Multi-Walled Carbon Nanotube/Polyimide Composites with High Dielectric Constants and Low Loss Factors

    NASA Technical Reports Server (NTRS)

    Elliott, Holly A.; Dudley, Kenneth L.; Smith, Joseph G.; Connell, John W.; Ghose, Sayata; Watson, Kent A.; Sun, Keun J.

    2009-01-01

    The measurement of observable electromagnetic phenomena in materials and their derived intrinsic electrical material properties are of prime importance in the discovery and development of material systems for electronic and aerospace applications. Nanocomposite materials comprised of metal decorated multi-walled carbon nanotubes (MWCNTs) were prepared by a facile method and characterized. Metal particles such as silver(Ag), platinum(Pt) and palladium(Pd) with diameters ranging from less than 5 to over 50 nanometers were distributed randomly on the MWCNTs. The present study is focused on silver decorated MWCNTs dispersed in a polyimide matrix. The Ag-containing MWCNTs were melt mixed into Ultem(TradeMark) and the mixture extruded as ribbons. The extruded ribbons exhibited a moderate to high degree of MWCNT alignment as determined by HRSEM. These ribbons were then fabricated into test specimens while maintaining MWCNT alignment and subsequently characterized for electrical and electromagnetic properties at 8-12 GHz. The results of the electromagnetic characterization showed that certain sample configurations exhibited a decoupling of the permittivity (epsilon ) and loss factor (epsilon") indicating that these properties could be tailored within certain limits. The decoupling and independent control of these fundamental electrical material parameters offers a new class of materials with potential applications in electronics, microwave engineering and optics.

  6. Metal Decorated Multi-Walled Carbon Nanotube/Polyimide Composites with High Dielectric Constants and Low Loss Factors

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Dudley, Kenneth L.; Elliott, Holly A.; Smith, Joseph G.; Connell, John W.

    2009-01-01

    The measurement of observable electromagnetic phenomena in materials and their derived intrinsic electric material properties are of prime importance in the discovery and development of material systems for electronic and aerospace applications. Nanocomposite materials comprised of metal decorated multi-walled carbon nanotubes (MWCNTs) were prepared by a facile method and characterized. Metal particles such as silver, platinum and palladium with diameters ranging from less than 5 to over 50 nanometers were distributed randomly on the MWCNTs. The metal-containing MWCNTs were then melt mixed into a polymer matrix and the mixture extruded as ribbons. These extruded ribbons exhibited a moderate to high degree of MWCNT alignment as determined by HRSEM. These ribbons were then fabricated into test specimens while maintaining MWCNT alignment and subsequently characterized for electromagnetic properties at 8-12 GHz. The present study is focused on silver decorated MWCNTs dispersed in an Ultem polyimide matrix. The results of the electromagnetic characterization showed that certain sample configurations exhibited a decoupling of the permittivity and loss factor (?? and ??) indicating that these properties could be tailored within certain limits. The decoupling and independent control of these fundamental electrical material parameters offer a new class of materials with potential applications in electronics, microwave engineering and optics.

  7. Highly selective electrodeposition of sub-10 nm crystalline noble metallic nanorods inside vertically aligned multiwall carbon nanotubes.

    PubMed

    Wang, Xuyang; Wang, Ranran; Wu, Qiang; Zhang, Xiaohua; Yang, Zhaohui; Guo, Jun; Chen, Muzi; Tang, Minghua; Cheng, Yajun; Chu, Haibin

    2016-07-08

    In this paper crystalline noble metallic nanorods including Au and Ag with sub-10 nm diameter, are encapsulated within prealigned and open-ended multiwall carbon nanotubes (MWCNTs) through an electrodeposition method. As the external surface of CNTs has been insulated by the epoxy the CNT channel becomes the only path for the mass transport as well as the nanoreactor for the metal deposition. Highly crystallized Au and Ag2O nanorods parallel to the radial direction of CNTs are confirmed by high-resolution transmission electron microscopy, energy dispersive x-ray spectroscopy and x-ray powder diffraction spectroscopy. The Ag2O nanorods are formed by air oxidation on the Ag metals and show a single crystalline structure with (111) planes. The Au nanorods exhibit a complex crystalline structure including twin-crystal and lattice dislocation with (111) and (200) planes. These crystalline noble metallic nanostructures may have important applications for nanocatalysts for fuel cells as well as nanoelectronic and nanophotonic devices. This method is deemed to benefit the precise deposition of other crystalline nanostructures inside CNTs with a small diameter.

  8. Highly selective electrodeposition of sub-10 nm crystalline noble metallic nanorods inside vertically aligned multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Xuyang; Wang, Ranran; Wu, Qiang; Zhang, Xiaohua; Yang, Zhaohui; Guo, Jun; Chen, Muzi; Tang, Minghua; Cheng, Yajun; Chu, Haibin

    2016-07-01

    In this paper crystalline noble metallic nanorods including Au and Ag with sub-10 nm diameter, are encapsulated within prealigned and open-ended multiwall carbon nanotubes (MWCNTs) through an electrodeposition method. As the external surface of CNTs has been insulated by the epoxy the CNT channel becomes the only path for the mass transport as well as the nanoreactor for the metal deposition. Highly crystallized Au and Ag2O nanorods parallel to the radial direction of CNTs are confirmed by high-resolution transmission electron microscopy, energy dispersive x-ray spectroscopy and x-ray powder diffraction spectroscopy. The Ag2O nanorods are formed by air oxidation on the Ag metals and show a single crystalline structure with (111) planes. The Au nanorods exhibit a complex crystalline structure including twin-crystal and lattice dislocation with (111) and (200) planes. These crystalline noble metallic nanostructures may have important applications for nanocatalysts for fuel cells as well as nanoelectronic and nanophotonic devices. This method is deemed to benefit the precise deposition of other crystalline nanostructures inside CNTs with a small diameter.

  9. A novel multi-walled carbon nanotube-based antibody conjugate for quantitative and semi-quantitative lateral flow assays.

    PubMed

    Sun, Wenjuan; Hu, Xiaolong; Liu, Jia; Zhang, Yurong; Lu, Jianzhong; Zeng, Libo

    2017-10-01

    In this study, the multi-walled carbon nanotubes (MWCNTs) were applied in lateral flow strips (LFS) for semi-quantitative and quantitative assays. Firstly, the solubility of MWCNTs was improved using various surfactants to enhance their biocompatibility for practical application. The dispersed MWCNTs were conjugated with the methamphetamine (MET) antibody in a non-covalent manner and then manufactured into the LFS for the quantitative detection of MET. The MWCNTs-based lateral flow assay (MWCNTs-LFA) exhibited an excellent linear relationship between the values of test line and MET when its concentration ranges from 62.5 to 1500 ng/mL. The sensitivity of the LFS was evaluated by conjugating MWCNTs with HCG antibody and the MWCNTs conjugated method is 10 times more sensitive than the one conjugated with classical colloidal gold nanoparticles. Taken together, our data demonstrate that MWCNTs-LFA is a more sensitive and reliable assay for semi-quantitative and quantitative detection which can be used in forensic analysis.

  10. Ultrasound-aided formation of gold nanoparticles on multi-walled carbon nanotubes functionalized with mercaptobenzene moieties.

    PubMed

    Park, Gle; Lee, Kyung G; Lee, Seok Jae; Park, Tae Jung; Wi, Ringbok; Wang, Kye Won; Kim, Do Hyun

    2011-07-01

    A hybrid of multi-walled carbon nanotube (MWCNT) and gold nanoparticle (Au NP) was prepared under ultrasound irradiation. The approach starts with the functionalization of the walls of MWCNTs with mercaptobenzene moieties for the subsequent immobilization of Au NPs. From the Raman spectra, mercaptobenzene was proven to exist on the MWCNTs. Gold ions were added to the aqueous dispersion of functionalized MWCNTs (f-MWCNTs), and were reduced with the aid of ultrasound and ammonium hydroxide. The reduced gold nanoparticles were examined from the TEM images. Au NPs adhered specifically on the thiol groups of mercaptobenzene to be deposited uniformly on the outer walls of the f-MWCNTs. The application of ultrasound led to a high yield of MWCNT-Au nanocomposites and to the dense distribution of the Au NPs. Moreover, the synthesis reaction rate of the hybrid was considerably enhanced relative to synthesis with mechanical agitation. Through an adsorption test using gold-binding-peptide-(GBP)-modified biomolecules, the hybrid's potential for biological diagnosis was verified.

  11. Reagentless biosensor based on layer-by-layer assembly of functional multiwall carbon nanotubes and enzyme-mediator biocomposite.

    PubMed

    Zhou, Xing-Hua; Xi, Feng-Na; Zhang, Yi-Ming; Lin, Xian-Fu

    2011-06-01

    A simple and controllable layer-by-layer (LBL) assembly method was proposed for the construction of reagentless biosensors based on electrostatic interaction between functional multiwall carbon nanotubes (MWNTs) and enzyme-mediator biocomposites. The carboxylated MWNTs were wrapped with polycations poly(allylamine hydrochloride) (PAH) and the resulting PAH-MWNTs were well dispersed and positively charged. As a water-soluble dye methylene blue (MB) could mix well with horseradish peroxidase (HRP) to form a biocompatible and negatively-charged HRP-MB biocomposite. A (PAH-MWNTs/HRP-MB)(n) bionanomultilayer was then prepared by electrostatic LBL assembly of PAH-MWNTs and HRP-MB on a polyelectrolyte precursor film-modified Au electrode. Due to the excellent biocompatibility of HRP-MB biocomposite and the uniform LBL assembly, the immobilized HRP could retain its natural bioactivity and MB could efficiently shuttle electrons between HRP and the electrode. The incorporation of MWNTs in the bionanomultilayer enhanced the surface coverage concentration of the electroactive enzyme and increased the catalytic current response of the electrode. The proposed biosensor displayed a fast response (2 s) to hydrogen peroxide with a low detection limit of 2.0×10⁻⁷ mol/L (S/N=3). This work provided a versatile platform in the further development of reagentless biosensors.

  12. Co-transport of chlordecone and sulfadiazine in the presence of functionalized multi-walled carbon nanotubes in soils.

    PubMed

    Zhang, Miaoyue; Engelhardt, Irina; Šimůnek, Jirka; Bradford, Scott A; Kasel, Daniela; Berns, Anne E; Vereecken, Harry; Klumpp, Erwin

    2017-02-01

    Batch and saturated soil column experiments were conducted to investigate sorption and mobility of two 14 C-labeled contaminants, the hydrophobic chlordecone (CLD) and the sulfadiazine (SDZ), in the absence or presence of functionalized multi-walled carbon nanotubes (MWCNTs). The transport behaviors of CLD, SDZ, and MWCNTs were studied at environmentally relevant concentrations (0.1-10 mg L -1 ) and they were applied in the column studies at different times. The breakthrough curves and retention profiles were simulated using a numerical model that accounted for the advective-dispersive transport of all compounds, attachment/detachment of MWCNTs, equilibrium and kinetic sorption of contaminants, and co-transport of contaminants with MWCNTs. The experimental results indicated that the presence of mobile MWCNTs facilitated remobilization of previously deposited CLD and its co-transport into deeper soil layers, while retained MWCNTs enhanced SDZ deposition in the topsoil layers due to the increased adsorption capacity of the soil. The modeling results then demonstrated that the mobility of engineered nanoparticles (ENPs) in the environment and the high affinity and entrapment of contaminants to ENPs were the main reasons for ENP-facilitated contaminant transport. On the other hand, immobile MWCNTs had a less significant impact on the contaminant transport, even though they were still able to enhance the adsorption capacity of the soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Effect of Spark-Plasma-Sintering Conditions on Tensile Properties of Aluminum Matrix Composites Reinforced with Multiwalled Carbon Nanotubes (MWCNTs)

    NASA Astrophysics Data System (ADS)

    Chen, B.; Imai, H.; Umeda, J.; Takahashi, M.; Kondoh, K.

    2017-04-01

    In this study, aluminum (Al) matrix composites containing 2 wt.% multiwalled carbon nanotubes (CNTs) were fabricated by powder metallurgy using high-energy ball milling (HEBM), spark plasma sintering (SPS), and subsequent hot extrusion. The effect of SPS conditions on the tensile properties of CNT/Al composites was investigated. The results showed that composites with well-dispersed CNTs and nearly full-density CNT/Al can be obtained. During HEBM, CNTs were shortened, inserted into welded Al powder particles, bonded to Al, and still stable without CNT-Al reaction. After consolidation, Al4C3 phases formed in composites under different sintering conditions. With the increase of sintering temperature and holding time, the strength decreased. Conversely, the ductility and toughness noticeably increased. As a result, a good balance between strength (367 MPa in ultimate tensile strength) and ductility (13% in elongation) was achieved in the as-extruded CNT/Al composite sintered at 630°C with a holding time of 300 min.

  14. Cellular uptake mechanisms of functionalised multi-walled carbon nanotubes by 3D electron tomography imaging

    NASA Astrophysics Data System (ADS)

    Al-Jamal, Khuloud T.; Nerl, Hannah; Müller, Karin H.; Ali-Boucetta, Hanene; Li, Shouping; Haynes, Peter D.; Jinschek, Joerg R.; Prato, Maurizio; Bianco, Alberto; Kostarelos, Kostas; Porter, Alexandra E.

    2011-06-01

    Carbon nanotubes (CNTs) are being investigated for a variety of biomedical applications. Despite numerous studies, the pathways by which carbon nanotubes enter cells and their subsequent intracellular trafficking and distribution remain poorly determined. Here, we use 3-D electron tomography techniques that offer optimum enhancement of contrast between carbon nanotubes and the plasma membrane to investigate the mechanisms involved in the cellular uptake of shortened, functionalised multi-walled carbon nanotubes (MWNT-NH3+). Both human lung epithelial (A549) cells, that are almost incapable of phagocytosis and primary macrophages, capable of extremely efficient phagocytosis, were used. We observed that MWNT-NH3+ were internalised in both phagocytic and non-phagocytic cells by any one of three mechanisms: (a) individually via membrane wrapping; (b) individually by direct membrane translocation; and (c) in clusters within vesicular compartments. At early time points following intracellular translocation, we noticed accumulation of nanotube material within various intracellular compartments, while a long-term (14-day) study using primary human macrophages revealed that MWNT-NH3+ were able to escape vesicular (phagosome) entrapment by translocating directly into the cytoplasm.Carbon nanotubes (CNTs) are being investigated for a variety of biomedical applications. Despite numerous studies, the pathways by which carbon nanotubes enter cells and their subsequent intracellular trafficking and distribution remain poorly determined. Here, we use 3-D electron tomography techniques that offer optimum enhancement of contrast between carbon nanotubes and the plasma membrane to investigate the mechanisms involved in the cellular uptake of shortened, functionalised multi-walled carbon nanotubes (MWNT-NH3+). Both human lung epithelial (A549) cells, that are almost incapable of phagocytosis and primary macrophages, capable of extremely efficient phagocytosis, were used. We observed

  15. Material with high dielectric constant, low dielectric loss, and good mechanical and thermal properties produced using multi-wall carbon nanotubes wrapped with poly(ether sulphone) in a poly(ether ether ketone) matrix

    NASA Astrophysics Data System (ADS)

    Zhang, Shuling; Wang, Hongsong; Wang, Guibin; Jiang, Zhenhua

    2012-07-01

    A material with high dielectric constant, low dielectric loss, and good mechanical and thermal properties was produced using multi-wall carbon nanotubes (MWCNTs) wrapped with poly(ether sulphone) (PES) dispersed in a poly(ether ether ketone) (PEEK) matrix. The material was fabricated using melt-blending, and MWCNT/PEEK composites show different degrees of improvement in the measured dielectric, mechanical, and thermal properties as compared to pure PEEK. This is attributed to the high conductivity of MWCNTs, the effect of wrapping MWCNTs with PES, the good dispersion of the wrapped MWCNTs in PEEK, and the strong interfacial adhesion between the wrapped MWCNTs and the PEEK.

  16. Cellular cytotoxic response induced by highly purified multi-wall carbon nanotube in human lung cells.

    PubMed

    Tsukahara, Tamotsu; Haniu, Hisao

    2011-06-01

    Carbon nanotubes, a promising nanomaterial with unique characteristics, have applications in a variety of fields. The cytotoxic effects of carbon nanotubes are partially due to the induction of oxidative stress; however, the detailed mechanisms of nanotube cytotoxicity and their interaction with cells remain unclear. In this study, the authors focus on the acute toxicity of vapor-grown carbon fiber, HTT2800, which is one of the most highly purified multi-wall carbon nanotubes (MWCNT) by high-temperature thermal treatment. The authors exposed human bronchial epithelial cells (BEAS-2B) to HTT2800 and measured the cellular uptake, mitochondrial function, cellular LDH release, apoptotic signaling, reactive oxygen species (ROS) generation and pro-inflammatory cytokine release. The HTT2800-exposed cells showed cellular uptake of the carbon nanotube, increased cell death, enhanced DNA damage, and induced cytokine release. However, the exposed cells showed no obvious intracellular ROS generation. These cellular and molecular findings suggest that HTT2800 could cause a potentially adverse inflammatory response in BEAS-2B cells.

  17. Dispersion and separation of nanostructured carbon in organic solvents

    NASA Technical Reports Server (NTRS)

    Evans, Christopher M. (Inventor); Ruf, Herbert J. (Inventor); Landi, Brian J. (Inventor); Raffaelle, Ryne P. (Inventor)

    2011-01-01

    The present invention relates to dispersions of nanostructured carbon in organic solvents containing alkyl amide compounds and/or diamide compounds. The invention also relates to methods of dispersing nanostructured carbon in organic solvents and methods of mobilizing nanostructured carbon. Also disclosed are methods of determining the purity of nanostructured carbon.

  18. Chlorophenol sorption on multi-walled carbon nanotubes: DFT modeling and structure-property relationship analysis.

    PubMed

    Watkins, Marquita; Sizochenko, Natalia; Moore, Quentarius; Golebiowski, Marek; Leszczynska, Danuta; Leszczynski, Jerzy

    2017-02-01

    The presence of chlorophenols in drinking water can be hazardous to human health. Understanding the mechanisms of adsorption under specific experimental conditions would be beneficial when developing methods to remove toxic substances from drinking water during water treatment in order to limit human exposure to these contaminants. In this study, we investigated the sorption of chlorophenols on multi-walled carbon nanotubes using a density functional theory (DFT) approach. This was applied to study selected interactions between six solvents, five types of nanotubes, and six chlorophenols. Experimental data were used to construct structure-adsorption relationship (SAR) models that describe the recovery process. Specific interactions between solvents and chlorophenols were taken into account in the calculations by using novel specific mixture descriptors.

  19. Micro/Nanomechanical characterization of multi-walled carbon nanotubes reinforced epoxy composite.

    PubMed

    Cui, Peng; Wang, Xinnan; Tangpong, X W

    2012-11-01

    In this paper, the mechanical properties of 1 wt.% multi-walled carbon nanotubes (MWCNTs) reinforced epoxy nanocomposites were characterized using a self-designed micro/nano three point bending tester that was on an atomic force microscope (AFM) to in situ observe MWCNTs movement on the sample surface under loading. The migration of an individual MWCNT at the surface of the nanocomposite was tracked to address the nanomechanical reinforcing mechanism of the nanocomposites. Through morphology analysis of the nanocomposite via scanning electron microscopy, AFM, and digital image correlation technique, it was found that the MWCNTs agglomerate and the bundles were the main factors for limiting the bending strength of the composites. The agglomeration/bundle effect was included in the Halpin-Tsai model to account for the elastic modulus of the nanocomposites.

  20. Skin effect mitigation in laser processed multi-walled carbon nanotube/copper conductors

    SciTech Connect

    Keramatnejad, K.; Zhou, Y. S.; Gao, Y.

    2015-10-21

    In this study, laser-processed multi-walled carbon nanotube (MWCNT)/Cu conductors are introduced as potential passive components to mitigate the skin effect of Cu at high frequencies (0–10 MHz). Suppressed skin effect is observed in the MWCNT/Cu conductors compared to primitive Cu. At an AC frequency of 10 MHz, a maximum AC resistance reduction of 94% was observed in a MWCNT/Cu conductor after being irradiated at a laser power density of 189 W/cm{sup 2}. The reduced skin effect in the MWCNT/Cu conductors is ascribed to the presence of MWCNT channels which are insensitive to AC frequencies. The laser irradiation process is observed to playmore » a crucial role in reducing contact resistance at the MWCNT-Cu interfaces, removing impurities in MWCNTs, and densifying MWCNT films.« less

  1. MnO2/multiwall carbon nanotube/Ni-foam hybrid electrode for electrochemical capacitor

    NASA Astrophysics Data System (ADS)

    Chen, L. H.; Li, L.; Qian, W. J.; Dong, C. K.

    2018-01-01

    The ternary composites of manganese dioxide/multiwall carbon nanotube/Ni-foam (MnO2/MWNT/Ni-foam) for supercapacitors were fabricated via a hydrothermal method after direct growth of MWNTs on the Ni-foam. The structural properties of the electrodes were characterized by SEM and TEM. The electrode exhibited excellent electrochemical properties from the investigation based on the three-electrode setup. Low contact resistance Rs of about 0.291 Ω between MnO2/MWNT and Ni-foam was reached benefited from the direct growth structure. High capacitance of 355.1 F/g at the current density of 2 A/g was achieved, with good capacitive response at high current density. The MnO2/MWNT/Ni-foam electrode exhibits good stability performance after 2000 cycles at a current of 40 mA.

  2. High Corrosion Resistance Offered by Multi-Walled Carbon Nanotubes Directly Grown Over Mild Steel Substrate

    NASA Astrophysics Data System (ADS)

    Arora, Sweety; Rekha, M. Y.; Gupta, Abhay; Srivastava, Chandan

    2018-02-01

    The inert and hydrophobic nature of carbon nanotubes (CNTs) makes them a potential material for corrosion protection coatings. In this work, a uniform coating of multi-walled CNTs (MWCNTs) was formed over a mild steel substrate by direct decomposition of a ferrocene-benzene mixture over the substrate which was kept inside a chemical vapor deposition setup at a temperature of 800°C. The MWCNTs formed over the substrate were characterized using x-ray diffraction, Raman spectroscopy and transmission electron microscopy techniques. Corrosion behavior of the bare and MWCNT-coated mild steel substrate was examined through potentiodynamic polarization and electrochemical impedance spectroscopy methods. A significant improvement in the corrosion resistance in terms of the reduction in corrosion current and corrosion rate and increase in polarization resistance was noted in the case of the MWCNT-coated mild steel plate. Corrosion resistance increased due to MWCNT coating.

  3. Toxicity of silver nanoparticles, multiwalled carbon nanotubes, and dendrimers assessed with multicellular organism Caenorhabditis elegans.

    PubMed

    Walczynska, Marta; Jakubowski, Witold; Wasiak, Tomasz; Kadziola, Kinga; Bartoszek, Nina; Kotarba, Sylwia; Siatkowska, Malgorzata; Komorowski, Piotr; Walkowiak, Bogdan

    2018-07-01

    Nematode Caenorhabditis elegans (C. elegans) was used to investigate the impact of silver nanoparticles (SNP), multiwalled carbon nanotubes (MWCNT), and polyamidoamine dendrimers (PAMAM) used in concentration of 10 10 particle/mL. Population-based observations and gene expression analysis were employed in this study. SNP and PAMAM caused decrease in the number of live nematodes and their body length, but MWCNT did not affect the population of nematodes. Gene expression analysis revealed significant changes caused by the presence of all studied nanomaterials, and the results strongly suggest a specific metabolic response of the nematode organism to exposure to various nanomaterials. It was shown that C. elegans is a very sensitive organism capable to respond specifically to the exposure to some nanomaterials and therefore could be considered as a possible biosensor for early warning of presence of some nanoparticles.

  4. Vertically aligned multiwalled carbon nanotubes for pressure, tactile and vibration sensing.

    PubMed

    Yilmazoglu, O; Popp, A; Pavlidis, D; Schneider, J J; Garth, D; Schüttler, F; Battenberg, G

    2012-03-02

    We report a simple method for the micro-nano integration of flexible, vertically aligned multiwalled CNT arrays sandwiched between a top and bottom carbon layer via a porous alumina (Al(2)O(3)) template approach. The electromechanical properties of the flexible CNT arrays have been investigated under mechanical stress conditions. First experiments show highly sensitive piezoresistive sensors with a resistance decrease of up to ∼35% and a spatial resolution of <1 mm. The results indicate that these CNT structures can be utilized for tactile sensing components. They also confirm the feasibility of accessing and utilizing nanoscopic CNT bundles via lithographic processing. The method involves room-temperature processing steps and standard microfabrication techniques.

  5. Biofunctionalization of multiwalled carbon nanotubes by irradiation of electropolymerized poly(pyrrole-diazirine) films.

    PubMed

    Papper, Vladislav; Gorgy, Karine; Elouarzaki, Kamal; Sukharaharja, Ayrine; Cosnier, Serge; Marks, Robert S

    2013-07-15

    A photoactivatable poly(pyrrole-diazirine) film was synthesized and electropolymerized as a versatile tool for covalent binding of laccase and glucose oxidase on multiwalled carbon nanotube coatings and Pt, respectively. Irradiation of the functionalized nanotubes allowed photochemical grafting of laccase and its subsequent direct electrical wiring, as illustrated by the electrocatalytic reduction of oxygen. Moreover, covalent binding of glucose oxidase as model enzyme, achieved by UV activation of electropolymerized pyrrole-diazirine, allowed a glucose biosensor to be realized. This original method to graft biomolecules combines electrochemical and photochemical techniques. The simplicity of this new method allows it to be extended easily to other biological systems. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Substituted copper phthalocyanine/multiwalled carbon nanotubes hybrid material for Cl{sub 2} sensing application

    SciTech Connect

    Sharma, Anshul Kumar, E-mail: dramanmahajan@yahoo.co.in; Saini, Rajan, E-mail: dramanmahajan@yahoo.co.in; Singh, Rajinder, E-mail: dramanmahajan@yahoo.co.in

    2014-04-24

    In this work, hybrid of soluble copper phthalocyanine (CuPcOC{sub 8}) and functionalized multi-walled carbon nanotubes (MWCNTs) has been synthesized. The formation of CuPcOC{sub 8}-MWCNTs hybrid is confirmed by atomic force microscopy, UV-Visible and FTIR spectroscopy. Subsequently, a chemi-resistive sensor is fabricated by drop casting CuPcOC{sub 8}-MWCNTs hybrid onto glass substrate. It has been demonstrated that CuPcOC{sub 8}-MWCNTs hybrid is highly selective towards Cl{sub 2} gas with minimum detection limit of 100 ppb. The response of sensor increases linearly with increase in the concentration of Cl{sub 2} gas. For 2000 ppb of Cl{sub 2}, CuPcOC{sub 8}-MWCNTs hybrid gives a response asmore » large as 53% in 40 seconds.« less

  7. One-step preparation of multiwall carbon nanotube/silicon hybrids for solar energy conversion

    NASA Astrophysics Data System (ADS)

    Lobiak, Egor V.; Bychanok, Dzmitry S.; Shlyakhova, Elena V.; Kuzhir, Polina P.; Maksimenko, Sergey A.; Bulusheva, Lyubov G.; Okotrub, Alexander V.

    2016-03-01

    The hybrid material consisting of a thin layer of multiwall carbon nanotubes (MWCNTs) on an n-doped silicon wafer was obtained in one step using an aerosol-assisted catalytic chemical vapor deposition. The MWCNTs were grown from a mixture of acetone and ethanol with ˜0.2 wt.% of iron polyoxomolybdate nanocluster of the keplerate-type structure. The samples produced at 800°C and 1050°C were tested as a solar energy converter. It was shown that photoresponse of the hybrid material significantly depends on the presence of structural defects in MWCNTs, being much higher in the case of more defective nanotubes. This is because defects lead to p-doping of nanotubes, whereas the p-n heterojunction between MWCNTs and silicon provides a high efficiency of the solar cell.

  8. Crystalline multiwall carbon nanotubes and their application as a field emission electron source.

    PubMed

    Liu, Peng; Zhou, Duanliang; Zhang, Chunhai; Wei, Haoming; Yang, Xinhe; Wu, Yang; Li, Qingwei; Liu, Changhong; Du, Bingchu; Liu, Liang; Jiang, Kaili; Fan, Shoushan

    2018-05-18

    Using super-aligned carbon nanotube (CNT) film, we have fabricated van der Waals crystalline multiwall CNTs (MWCNT) by adopting high pressure and high temperature processing. The CNTs keep parallel to each other and are distributed uniformly. X-ray diffraction characterization shows peaks at the small angle range, which can be assigned to the spacing of the MWCNT crystals. The mechanical, electrical and thermal properties are all greatly improved compared with the original CNT film. The field emission properties of van der Waals crystalline MWCNTs are tested and they show a better surface morphology stability for the large emission current. We have further fabricated a field emission x-ray tube and demonstrated a precise resolution imaging ability.

  9. Superhydrophobic to hydrophilic transition of multi-walled carbon nanotubes induced by Na+ ion irradiation

    NASA Astrophysics Data System (ADS)

    Das, Pritam; Dhal, Satyanarayan; Ghosh, Susanta; Chatterjee, Sriparna; Rout, Chandra S.; Ramgir, Niranjan; Chatterjee, Shyamal

    2017-12-01

    Multi-walled carbon nanotubes (MWCNT) having diameter in the range of 5-30 nm were coated on silicon wafer using spray coating technique. The coated film was irradiated with 5 keV Na+ at a fluence of 1 × 1016 ions·cm-2. A large-scale welding is observed in the post-irradiated nanotube assembly under scanning electron microscope. We have studied dynamic wetting properties of the nanotubes. While the pristine MWCNT shows superhydrophobic nature, the irradiated MWCNT turns into hydrophilic. Our simulation based on iradina and experimental evidences show defect formation in MWCNT due to ion irradiation. We have invoked mechanism based on defect mediated adsorption of water, which plays major role for transition from superhydrophobic to hydrophilic.

  10. MHDA-Functionalized Multiwall Carbon Nanotubes for detecting non-aromatic VOCs

    NASA Astrophysics Data System (ADS)

    Thamri, Atef; Baccar, Hamdi; Struzzi, Claudia; Bittencourt, Carla; Abdelghani, Adnane; Llobet, Eduard

    2016-10-01

    The chemical modification of multiwalled carbon nanotubes (MWCNTs) with a long chain mercapto acid is reported as a way to improve sensitivity and response time of gas sensors for detecting alcohols, acetone and toxic gases such as DMMP. We have developed sensors employing MWCNTs decorated with gold nanoparticles and modified with a 16-mercaptohexadecanoic acid (MHDA) monolayer. Morphological and compositional analysis by Transmission Electron Microscopy (TEM), Fourier Transform Infra-red Spectroscopy (FTIR) and X-ray photoelectron spectroscopy were performed to characterize the gold nanoparticles and to check the bonding of the thiol monolayer. The detection of aromatic and non-aromatic volatiles and DMMP vapors by MWCNT/Au and MWCNT/Au/MHDA shows that the presence of the self-assembled layer increases sensitivity and selectivity towards non-aromatics. Furthermore, it ameliorates response dynamics, and significantly reduces nitrogen dioxide and moisture cross-sensitivity.

  11. Planarized arrays of aligned, untangled multiwall carbon nanotubes with Ohmic back contacts

    DOE PAGES

    Rochford, C.; Limmer, S. J.; Howell, S. W.; ...

    2014-11-26

    Vertically aligned, untangled planarized arrays of multiwall carbon nanotubes (MWNTs) with Ohmic back contacts were grown in nanopore templates on arbitrary substrates. The templates were prepared by sputter depositing Nd-doped Al films onto W-coated substrates, followed by anodization to form an aluminum oxide nanopore array. The W underlayer helps eliminate the aluminum oxide barrier that typically occurs at the nanopore bottoms by instead forming a thin WO 3 layer. The WO 3 can be selectively etched to enable electrodeposition of Co catalysts with control over the Co site density. This led to control of the site density of MWNTs grownmore » by thermal chemical vapor deposition, with the W also serving as a back electrical contact. As a result, Ohmic contact to MWNTs was confirmed, even following ultrasonic cutting of the entire array to a uniform height.« less

  12. Anchorage of γ-Al 2O 3 nanoparticles on nitrogen-doped multiwalled carbon nanotubes

    DOE PAGES

    Rodríguez-Pulido, A.; Martínez-Gutiérrez, H.; Calderon-Polania, G. A.; ...

    2016-06-07

    Nitrogen-doped multiwalled carbon nanotubes (CNx-MWNTs) have been decorated with γ-Al 2O 3 nanoparticles by a novel method. This process involved a wet chemical approach in conjunction with thermal treatment. During the particle anchoring process, individual CNx-MWNT nanotubes agglomerated into bundles, resulting in arrays of aligned CNx-MWNT coated with γ-Al 2O 3. Extensive characterization of the resulting γ-Al 2O 3/CNx-MWNT bundles was performed using a range of electron microscopy imaging and microanalytical techniques. In conclusion, a possible mechanism explaining the nanobundle alignment is described, and possible applications of these materials for the fabrication of ceramic composites using CNx-MWNTs are briefly discussed.

  13. Electrical response of liquid crystal cells doped with multi-walled carbon nanotubes.

    PubMed

    García-García, Amanda; Vergaz, Ricardo; Algorri, José Francisco; Quintana, Xabier; Otón, José Manuel

    2015-01-01

    The inclusion of nanoparticles modifies a number of fundamental properties of many materials. Doping of nanoparticles in self-organized materials such as liquid crystals may be of interest for the reciprocal interaction between the matrix and the nanoparticles. Elongated nanoparticles and nanotubes can be aligned and reoriented by the liquid crystal, inducing noticeable changes in their optical and electrical properties. In this work, cells of liquid crystal doped with high aspect ratio multi-walled carbon nanotubes have been prepared, and their characteristic impedance has been studied at different frequencies and excitation voltages. The results demonstrate alterations in the anisotropic conductivity of the samples with the applied electric field, which can be followed by monitoring the impedance evolution with the excitation voltage. Results are consistent with a possible electric contact between the coated substrates of the LC cell caused by the reorientation of the nanotubes. The reversibility of the doped system upon removal of the electric field is quite low.

  14. Simple quantification of surface carboxylic acids on chemically oxidized multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Gong, Hyejin; Kim, Seong-Taek; Lee, Jong Doo; Yim, Sanggyu

    2013-02-01

    The surface of multi-walled carbon nanotube (MWCNT) was chemically oxidized using nitric acid and sulfuric-nitric acid mixtures. Thermogravimetric analysis, transmission electron microscopy and infrared spectroscopy revealed that the use of acid mixtures led to higher degree of oxidation. More quantitative identification of surface carboxylic acids was carried out using X-ray photoelectron spectroscopy (XPS) and acid-base titration. However, these techniques are costly and require very long analysis times to promptly respond to the extent of the reaction. We propose a much simpler method using pH measurements and pre-determined pKa value in order to estimate the concentration of carboxylic acids on the oxidized MWCNT surfaces. The results from this technique were consistent with those obtained from XPS and titration, and it is expected that this simple quantification method can provide a cheap and fast way to monitor and control the oxidation reaction of MWCNT.

  15. Surface-initiated graft polymerization on multiwalled carbon nanotubes pretreated by corona discharge at atmospheric pressure.

    PubMed

    Xu, Lihua; Fang, Zhengping; Song, Ping'an; Peng, Mao

    2010-03-01

    Surface-initiated graft polymerization on multi-walled carbon nanotubes pretreated with a corona discharge at atmospheric pressure was explored. The mechanism of the corona-discharge-induced graft polymerization is discussed. The results indicate that MWCNTs were encapsulated by poly(glycidyl methacrylate) (PGMA), demonstrating the formation of PGMA-grafted MWCNTs (PGMA-g-MWCNTs), with a grafting ratio of about 22 wt%. The solubility of PGMA-g-MWCNTs in ethanol was dramatically improved compared to pristine MWCNTs, which could contribute to fabricating high-performance polymer/MWCNTs nanocomposites in the future. Compared with most plasma processes, which operate at low pressures, corona discharge has the merit of working at atmospheric pressure.

  16. Electrophoretically deposited multiwalled carbon nanotube based amperometric genosensor for E.coli detection

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Hema; Solanki, Shipra; Sumana, Gajjala

    2016-04-01

    This work reports on a sensitive and selective genosensor fabrication method for Escherichia coli (E.coli) detection. The functionalized multiwalled carbon nanotubes (MWCNT) synthesized via chemical vapour deposition have been deposited electrophoretically onto indium tin oxide coated glass surface and have been utilized as matrices for the covalent immobilization of E.coli specific probe oligonucleotide that was identified from the 16s rRNA coding region of the E.coli genome. This fabricated functionalized MWCNT based platform sought to provide improved fundamental characteristics to electrode interface in terms of electro-active surface area and diffusion coefficient. Electrochemical cyclic voltammetry revealed that this genosensor exhibits a linear response to complementary DNA in the concentration range of 10-7 to 10-12 M with a detection limit of 1×10-12 M.

  17. Facile synthesis of stable superhydrophobic nanocomposite based on multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Mokarian, Zahra; Rasuli, Reza; Abedini, Yousefali

    2016-04-01

    A facile approach to fabricate a stable superhydrophobic composite comprising multi-walled carbon nanotubes and silicone rubber has been reported. Contact angle of de-ionized water droplets on the prepared surface was measured with the value of near 159°; while water droplets easily rolled off and bounced on it. Surface free energy of the superhydrophobic coating was examined by three methods about 26 mJ/m2. The prepared film shows good stability under high stress conditions such as ultraviolet exposure, heating, pencil hardness test, attacking with different pH value and ionic-strength solutions. In addition, remarkable stability of the coating was observed after soaking in condensed hydrochloric acid, 5 wt.% NaCl aqueous solution, boiling water and tape test.

  18. Skin effect mitigation in laser processed multi-walled carbon nanotube/copper conductors

    NASA Astrophysics Data System (ADS)

    Keramatnejad, K.; Zhou, Y. S.; Gao, Y.; Rabiee Golgir, H.; Wang, M.; Jiang, L.; Silvain, J.-F.; Lu, Y. F.

    2015-10-01

    In this study, laser-processed multi-walled carbon nanotube (MWCNT)/Cu conductors are introduced as potential passive components to mitigate the skin effect of Cu at high frequencies (0-10 MHz). Suppressed skin effect is observed in the MWCNT/Cu conductors compared to primitive Cu. At an AC frequency of 10 MHz, a maximum AC resistance reduction of 94% was observed in a MWCNT/Cu conductor after being irradiated at a laser power density of 189 W/cm2. The reduced skin effect in the MWCNT/Cu conductors is ascribed to the presence of MWCNT channels which are insensitive to AC frequencies. The laser irradiation process is observed to play a crucial role in reducing contact resistance at the MWCNT-Cu interfaces, removing impurities in MWCNTs, and densifying MWCNT films.

  19. Gold nanoparticle decorated multi-walled carbon nanotubes as counter electrode for dye sensitized solar cells.

    PubMed

    Kaniyoor, Adarsh; Ramaprabhu, Sundara

    2012-11-01

    A novel counter electrode material for dye sensitized solar cells (DSSCs) composed of nanostructured Au particles decorated on functionalized multi-walled carbon nanotubes (f-MWNTs) is demonstrated for the first time. MWNTs synthesized by catalytic chemical vapor deposition technique are purified and functionalized by treating with concentrated acids. Au nanoparticles are decorated on f-MWNTs by a rapid and facile microwave assisted polyol reduction method. The materials are characterized by X-ray diffractometry, Fourier transform infra red spectroscopy and electron microscopy. The DSSC fabricated with Au/f-MWNTs based counter electrode shows enhanced power conversion efficiency (eta) of 4.9% under AM 1.5G simulated solar radiation. In comparison, the reference DSSCs fabricated with f-MWNTs and Pt counter electrodes show eta of 2.1% and 4.5%. This high performance of Au/f-MWNTs counter electrode is investigated using electrochemical impedance spectroscopy and cyclic voltammetry studies.

  20. Adsorption and desorption of oxytetracycline and carbamazepine by multiwalled carbon nanotubes.

    PubMed

    Oleszczuk, Patryk; Pan, Bo; Xing, Baoshan

    2009-12-15

    We investigated the adsorption-desorption by multiwalled carbon nanotubes (MWCNTs) of two pharmaceuticals, oxytetracycline (OTC) and carbamazepine (CBZ). The pharmaceuticals demonstrated relatively fast sorption kinetics on MWCNTs. All adsorption isotherms were nonlinear and fit the Polanyi-Manes model (PMM). The single point adsorption coefficient (K) values for OTC were more than 1 order of magnitude higher than those for CBZ on corresponding MWCNTs. The adsorbed volume capacity (Q(0)) and K values of PMM showed a significant relationship with surface areas and the meso- and micropore volume of MWCNTs for both chemicals. Depending on the MWCNT outer diameter, 13.8-25.2% and 62.7-90.6% of initially adsorbed OTC and CBZ, respectively, were desorbed after 200 h. The rate of desorption of both OTC and CBZ depended upon pH and the quantity of initially adsorbed pharmaceuticals, as well as aggregation in the case of OTC.

  1. Incorporation of Multiwalled Carbon Nanotubes into High Temperature Resin Using Dry Mixing Techniques

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Delozier, Donavon M.; Working, Dennis C.; Siochi, Emilie J.; Connell, John W.

    2006-01-01

    As part of an ongoing effort to develop multifunctional advanced composites, blends of PETI330 and multiwalled carbon nanotubes (MWNTs) were prepared and characterized. Dry mixing techniques were employed and the maximum loading level of the MWNT chosen was based primarily on its effect on melt viscosity. The PETI330/ MWNT mixtures were prepared at concentrations ranging from 3 to 25 wt %. The resulting powders were characterized for homogeneity, thermal and rheological properties and extrudability as continuous fibers. Based on the characterization results, samples containing 10, 15 and 20 wt % MWNTs were chosen for more comprehensive evaluation. Samples were also prepared using in situ polymerization and solution mixing techniques and their properties were compared with the ball-mill prepared samples. The preparation and characterization of PETI330/ MWNT nanocomposites are discussed herein.

  2. Adsorption of Arsenic on Multiwall Carbon Nanotube–Zirconia Nanohybrid for Potential Drinking Water Purification

    PubMed Central

    AddoNtim, Susana; Mitra, Somenath

    2012-01-01

    The adsorptive removal of arsenic from water using a multiwall carbon nanotube-zirconia nanohybrid (MWCNT-ZrO2) is presented. The MWCNT-ZrO2 with 4.85% zirconia was effective in meeting the drinking water standard levels of 10 μg L−1. The absorption capacity of the composite were 2000 μg g−1 and 5000 μg g−1 for As (III) and As (V) respectively, which were significantly higher than those reported previously for iron oxide coated MWCNTs. The adsorption of As (V) on MWCNT-ZrO2 was faster than that of As (III), and a pseudo-second order rate equation effectively described the uptake kinetics. The adsorption isotherms for As (III) and As (V) fitted both the Langmuir and Freundlich models. A major advantage of the MWCNT-ZrO2 was that the adsorption capacity was not a function of pH. PMID:22424815

  3. Alternative mannosylation method for nanomaterials: application to oxidized debris-free multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    de Sousa, Marcelo; Martinez, Diego Stéfani Teodoro; Alves, Oswaldo Luiz

    2016-06-01

    Mannosylation is a method commonly used to deliver nanomaterials to specific organs and tissues via cellular macrophage uptake. In this work, for the first time, we proposed a method that involves the binding of d-mannose to ethylenediamine to form mannosylated ethylenediamine, which is then coupled to oxidized and purified multiwalled carbon nanotubes. The advantage of this approach is that mannosylated ethylenediamine precipitates in methanol, which greatly facilitates the separation of this product in the synthesis process. Carbon nanotubes were oxidized using concentrated H2SO4 and HNO3 by conventional reflux method. However, during this oxidation process, carbon nanotubes generated carboxylated carbonaceous fragments (oxidation debris). These by-products were removed from the oxidized carbon nanotubes to ensure that the functionalization would occur only on the carbon nanotube surface. The coupling of mannosylated ethylenediamine to debris-free carbon nanotubes was accomplished using n-(3-dimethylaminopropyl)-n-ethylcarbodiimide and n-hydroxysuccinimide. Deconvoluted N1s spectra obtained from X-ray photoelectron spectroscopy gave binding energies of 399.8 and 401.7 eV, which we attributed to the amide and amine groups, respectively, of carbon nanotubes functionalized with mannosylated ethylenediamine. Deconvoluted O1s spectra showed a binding energy of 532.4 eV, which we suggest is caused by an overlap in the binding energies of the aliphatic CO groups of d-mannose and the O=C group of the amide bond. The functionalization degree was approximately 3.4 %, according to the thermogravimetric analysis. Scanning electron microscopy demonstrated that an extended carbon nanotube morphology was preserved following the oxidation, purification, and functionalization steps.

  4. Enhanced-Adhesion Multi-Walled Carbon Nanotubes on Titanium Substrates for Stray Light Control

    NASA Technical Reports Server (NTRS)

    Hagopian, John; Getty, Stephanie; Quijada, Manuel

    2012-01-01

    Carbon nanotubes previously grown on silicon have extremely low reflectance, making them a good candidate for stray light suppression. Silicon, however, is not a good structural material for stray light components such as tubes, stops, and baffles. Titanium is a good structural material and can tolerate the 700 C nanotube growth process. The ability to grow carbon nanotubes on a titanium substrate that are ten times blacker than the current NASA state-of-the-art paints in the visible to near infrared spectra has been achieved. This innovation will allow significant improvement of stray light performance in scientific instruments or any other optical system. This innovation is a refinement of the utilization of multiwalled carbon nano tubes for stray light suppression in spaceflight instruments. The innovation is a process to make the surface darker and improve the adhesion to the substrate, improving robustness for spaceflight use. Bright objects such as clouds or ice scatter light off of instrument structures and components and make it difficult to see dim objects in Earth observations. A darker material to suppress this stray light has multiple benefits to these observations, including enabling scientific observations not currently possible, increasing observational efficiencies in high-contrast scenes, and simplifying instruments and lowering their cost by utilizing fewer stray light components and achieving equivalent performance. The prior art was to use commercially available black paint, which resulted in approximately 4% of the light being reflected (hemispherical reflectance or total integrated scatter, or TIS). Use of multiwalled carbon nanotubes on titanium components such as baffles, entrance aperture, tubes, and stops, can decrease this scattered light by a factor of ten per bounce over the 200-nm to 2,500-nm wavelength range. This can improve system stray light performance by orders of magnitude. The purpose of the innovation is to provide an enhanced

  5. Size- and shape-dependent pleural translocation, deposition, fibrogenesis, and mesothelial proliferation by multiwalled carbon nanotubes

    PubMed Central

    Xu, Jiegou; Alexander, David B; Futakuchi, Mitsuru; Numano, Takamasa; Fukamachi, Katsumi; Suzui, Masumi; Omori, Toyonori; Kanno, Jun; Hirose, Akihiko; Tsuda, Hiroyuki

    2014-01-01

    Multiwalled carbon nanotubes (MWCNT) have a fibrous structure similar to asbestos, raising concern that MWCNT exposure may lead to asbestos-like diseases. Previously we showed that MWCNT translocated from the lung alveoli into the pleural cavity and caused mesothelial proliferation and fibrosis in the visceral pleura. Multiwalled carbon nanotubes were not found in the parietal pleura, the initial site of development of asbestos-caused pleural diseases in humans, probably due to the short exposure period of the study. In the present study, we extended the exposure period to 24 weeks to determine whether the size and shape of MWCNT impact on deposition and lesion development in the pleura and lung. Two different MWCNTs were chosen for this study: a larger sized needle-like MWCNT (MWCNT-L; l = 8 μm, d = 150 nm), and a smaller sized MWCNT (MWCNT-S; l = 3 μm, d = 15 nm), which forms cotton candy-like aggregates. Both MWCNT-L and MWCNT-S suspensions were administered to the rat lung once every 2 weeks for 24 weeks by transtracheal intrapulmonary spraying. It was found that MWCNT-L, but not MWCNT-S, translocated into the pleural cavity, deposited in the parietal pleura, and induced fibrosis and patchy parietal mesothelial proliferation lesions. In addition, MWCNT-L induced stronger inflammatory reactions including increased inflammatory cell number and cytokine/chemokine levels in the pleural cavity lavage than MWCNT-S. In contrast, MWCNT-S induced stronger inflammation and higher 8-hydroxydeoxyguanosine level in the lung tissue than MWCNT-L. These results suggest that MWCNT-L has higher risk of causing asbestos-like pleural lesions relevant to mesothelioma development. PMID:24815191

  6. Adsorption of crystal violet onto functionalised multi-walled carbon nanotubes: Equilibrium and kinetic studies.

    PubMed

    Sabna, V; Thampi, Santosh G; Chandrakaran, S

    2016-12-01

    Synthetic dyes present in effluent from textile, paper and paint industries contain crystal violet (CV), a known carcinogenic agent. This study investigates the modification of multiwalled carbon nanotubes by acid reflux method and equilibrium and kinetic behaviour of adsorption of CV onto functionalized multi-walled carbon nanotubes (fMWNTs) in batch system. High stability of the fMWNTs suspension in water indicates the hydrophilicity of fMWNTs induced due to the formation of functional groups that make hydrogen bonds with water molecules. fMWNTs were characterized by Fourier Transform Infra Red (FTIR) spectroscopy and the functional groups present on the fMWNTs were confirmed. Characteristic variation was observed in the FTIR spectra of fMWNTs after adsorption of crystal violet onto it. Adsorption characteristics were evaluated as a function of system variables such as contact time, dosage of fMWNTs and initial concentration and pH of the crystal violet solution. Adsorption capacity of fMWNTs and percentage removal of the dye increased with increase in contact time, adsorbent dosage and pH but declined with increase in initial concentration of the dye. fMWNTs showed higher adsorption capacity compared to that of pristine MWNTs. Data showed good fit with the Langmuir and Freundlich isotherm models and the pseudo-second order kinetic model; the maximum adsorption capacity was 90.52mg/g. Kinetic parameters such as rate constants, equilibrium adsorption capacities and regression coefficients were estimated. Results indicate that fMWNTs are an effective adsorbent for the removal of crystal violet from aqueous solution. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Adsorption of methyl green dye onto multi-walled carbon nanotubes decorated with Ni nanoferrite

    NASA Astrophysics Data System (ADS)

    Bahgat, Mohamed; Farghali, Ahmed Ali; El Rouby, Waleed; Khedr, Mohamed; Mohassab-Ahmed, Mohassab Y.

    2013-06-01

    This research was carried out to evaluate the capability of multi-walled carbon nanotubes (CNTs) and NiFe2O4-decorated multi-walled carbon nanotubes (NiFe2O4-CNTs) toward waste water treatment relevant to organic dyes. CNTs were prepared via chemical vapor deposition method. NiFe2O4-CNTs were prepared by in-situ chemical precipitation of metal hydroxides followed by hydrothermal processing. The samples were characterized using XRD and TEM. The adsorption efficiency of CNTs and NiFe2O4-CNTs of methyl green dye at various temperatures was examined. The adsorbed amount increased with the CNTs and NiFe2O4-CNTs dosage. The linear correlation coefficients and standard deviations of Langmuir and Freundlich isotherms were determined. It was found that Langmuir isotherm fitted the experimental results well in both adsorption cases n of methyl green onto CNTs and NiFe2O4-CNTs. Kinetics analyses were conducted using pseudo first-order, second-order and the intraparticle diffusion models. The results showed that the adsorption kinetics was controlled by a pseudo second-order model for adsorption of methyl green onto CNTs and best controlled by pseudo first-order in case of NiFe2O4-CNTs. Changes in the free energy of adsorption (Δ G°), enthalpy (Δ H°), entropy (Δ S°), and the activation energy ( E a) were determined. The Δ H°, Δ G° and E a values indicated that the adsorption of methyl green onto MWCNTs and NiFe2O4-MWCNTs was physisorption.

  8. Electrochemical sensor for terbutaline sulfate based on a glassy carbon electrode modified with grapheme and multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Li, Zhou; Hua, Xin; Pei, Hongying; Shen, Yuan; Shen, Guijun

    2017-12-01

    A glass carbon electrode was prepared that coated with a composite film containing grapheme and multi-walled carbon nanotubes. It was used to study the electrochemical response of terbutaline sulfate. Under the optimized conditions, the oxidation peak current was found to be proportional to its concentration in the range of 0.2-5 μmol·L-1 and 5-40 μmol·L-1).Compared with the bare GC electrode, the GN-MWNTs-modified GC (GN-MWNTs/GC) had many advantages such as relatively high sensitivity, good stability and long life time. The modified electrode was used to determine the TES tablets with satisfactory results.

  9. Lightning Damage of Carbon Fiber/Epoxy Laminates with Interlayers Modified by Nickel-Coated Multi-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Dong, Qi; Wan, Guoshun; Xu, Yongzheng; Guo, Yunli; Du, Tianxiang; Yi, Xiaosu; Jia, Yuxi

    2017-12-01

    The numerical model of carbon fiber reinforced polymer (CFRP) laminates with electrically modified interlayers subjected to lightning strike is constructed through finite element simulation, in which both intra-laminar and inter-laminar lightning damages are considered by means of coupled electrical-thermal-pyrolytic analysis method. Then the lightning damage extents including the damage volume and maximum damage depth are investigated. The results reveal that the simulated lightning damages could be qualitatively compared to the experimental counterparts of CFRP laminates with interlayers modified by nickel-coated multi-walled carbon nanotubes (Ni-MWCNTs). With higher electrical conductivity of modified interlayer and more amount of modified interlayers, both damage volume and maximum damage depth are reduced. This work provides an effective guidance to the anti-lightning optimization of CFRP laminates.

  10. Adsorptive Behavior and Voltammetric Determination of Hydralazine Hydrochloride at A Glassy Carbon Electrode Modified with Multiwalled Carbon Nanotubes

    PubMed Central

    Khodadadian, Mehdi; Jalili, Ronak; Bahrami, Mohammad Taher; Bahrami, Gholamreza

    2017-01-01

    An electroanalytical method has been introduced for highly sensitive determination of hydralazine hydrochloride (Hy-HCl) based on its oxidation at a glassy carbon electrode modified with multiwalled carbon nanotubes (MWCNT/GCE). Studies showed that the electrochemical oxidation of Hy-HCl was accompanied by adsorption and highly sensitive responses could be achieved by adsorptive stripping voltammetry. The electrooxidation of Hy-HCl at MWCNT/GCE occurred at ~32 mV which was lower than that observed at bare GCE (~52 mV). The optimum working conditions for determination of the drug using differential-pulse adsorptive stripping voltammetry (DPAdSV) were established. The method exhibited linear responses to Hy-HCl in the concentration range 10-220 nM with a detection limit of 2.7 nM. The proposed method was successfully applied to the determination of this compound in pharmaceutical dosage forms. PMID:29552043

  11. Graphite nanoplatelets/multiwalled carbon nanotubes hybrid nanostructure for electrochemical capacitor.

    PubMed

    Mishra, Ashish Kumar; Ramaprabhu, S

    2012-08-01

    Recently, the focus on carbon based nanostructures for various applications has been due to their novel properties such as high electrical conductivity, high mechanical strength and high surface area. In the present work, we have investigated the charge storage capacity of modified graphite nanoplatelets and hybrid structure of graphite nanoplatelets-multiwalled carbon nanotubes (MWNTs). These MWNTs can be used as spacers to reduce the possibility of restacking of graphite nanoplatelets and hence increases the surface area of the hybrid carbon nanostructure thereby high degree of metal oxide decoration is achieved over the hybrid structure. MWNTs were prepared by catalytic chemical vapor deposition technique and further purified with air oxidation and acid treatment. Graphite was treated with conc. nitric acid and sulphuric acid in the volumetric ratio of 1:3 for 3 days and these modified graphite nanoplatelets were further stirred with MWNTs in equal weight ratio to form hybrid nanostructure. Further, ruthenium oxide (RuO2) nanoparticles were decorated on this hybrid structure using chemical route followed by calcination. RuO2 decorated hybrid carbon nanostructure was characterized by using X-ray diffraction, Electron microscopy and Raman spectroscopy. The performance of the hybrid structure based nanocomposite as electrochemical capacitor electrodes was analyzed by studing its capacitive and charge-discharge behaviours using cyclic voltammetry and chronopotentiometry techniques and the results have been discussed.

  12. Nanocomposites from Stable Dispersions of Carbon Nanotubes in Polymeric Matrices Using Dispersion Interaction

    NASA Technical Reports Server (NTRS)

    Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Kang, Jin Ho (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor)

    2016-01-01

    Stable dispersions of carbon nanotubes (CNTs) in polymeric matrices include CNTs dispersed in a host polymer or copolymer whose monomers have delocalized electron orbitals, so that a dispersion interaction results between the host polymer or copolymer and the CNTs dispersed therein. Nanocomposite products, which are presented in bulk, or when fabricated as a film, fiber, foam, coating, adhesive, paste, or molding, are prepared by standard means from the present stable dispersions of CNTs in polymeric matrices, employing dispersion interactions, as presented hereinabove.

  13. Multi-walled Carbon Nanotubes Reduce Toxicity of Diphenhydramine to Ceriodaphnia dubia in Water and Sediment Exposures.

    PubMed

    Myer, Mark H; Black, Marsha C

    2017-09-01

    Multi-walled carbon nanotubes are adsorptive materials that have potential for remediation of organic contaminants in water. Sediment elutriate exposures were undertaken with Ceriodaphnia dubia to compare the toxic effects of diphenhydramine in the presence and absence of sediment and multi-walled carbon nanotubes. In both sediment and solution-only treatments, addition of 0.318 mg/g of carbon nanotubes significantly decreased 48-h mortality relative to control, with a 78.7%-90.1% reduction in treatments with nanotube-amended sediment and 40.7%-53.3% reduction in nanotube-amended water exposures. The greatest degree of relative mortality reduction occurred in sediments containing higher levels of natural organic matter, indicating a potential additive effect.

  14. Bioaccumulation, stress, and swimming impairment in Daphnia magna exposed to multiwalled carbon nanotubes, graphene, and graphene oxide.

    PubMed

    Cano, Amanda M; Maul, Jonathan D; Saed, Mohammad; Shah, Smit A; Green, Micah J; Cañas-Carrell, Jaclyn E

    2017-08-01

    The use of carbon-based nanomaterials (CNMs) such as multiwalled carbon nanotubes (MWCNTs), graphene, and graphene oxide (GO) is increasing across many applications because of their unique and versatile properties. These CNMs may enter the aquatic environment through many pathways, creating the potential for organism exposure. The present study addresses the bioaccumulation and toxicity seen in Daphnia magna exposed to CNMs dispersed in sodium dodecyl benzene sulfonate (SDBS). In study I, D. magna were exposed to varying outer diameters of MWCNTs for 24 h in moderately hard or hard freshwater. Bioaccumulation of MWCNT was found in all treatments, with the highest concentrations (0.53 ± 0.27 μg/g) in D. magna exposed in hard freshwater (p < 0.005). The median lethal concentration (LC50) was determined for D. magna exposed to CNMs in moderately hard and hard freshwater. In study II, D. magna were exposed to CNMs for 72 h in moderately hard freshwater to assess swimming velocity and generation of reactive oxygen species (ROS) detected by dichlorofluorescein fluorescence. An overall decrease was seen in D. magna swimming velocity after exposure to CNMs. The generation of ROS was significantly higher (1.54 ± 0.38 dichlorofluorescein mM/mg dry wt) in D. magna exposed to MWCNTs of smaller outer diameters than in controls after 72 h (p < 0.05). These results suggest that further investigation of CNM toxicity and behavior in the aquatic environment is needed. Environ Toxicol Chem 2017;36:2199-2204. © 2017 SETAC. © 2017 SETAC.

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

    PubMed

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

    2012-02-15

    In this work, magnetic carbon nanotubes (CNTs) were prepared by mixing the magnetic particles and multi-walled carbon nanotubes dispersed solutions. Due to their excellent adsorption capability towards hydrophobic compounds, the magnetic CNTs were used as adsorbent of magnetic solid-phase extraction (MSPE) to extract phthalate acid esters (PAEs), which are widely used in many consumable products with potential carcinogenic properties. By coupling MSPE with gas chromatography/mass spectrometry (GC/MS), a rapid, sensitive and cost-effective method for the analysis of PAEs was established. Our results showed that the limits of detection (LODs) of 16 PAEs ranged from 4.9 to 38 ng L(-1), which are much lower compared to the previously reported methods. And good linearities of the detection method were obtained with correlation coefficients (R(2)) between 0.9821 and 0.9993. In addition, a satisfying reproducibility was achieved by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) less than 11.7% and 14.6%, respectively. Finally, the established MSPE-GC/MS method was successfully applied to the determination of PAEs from bottled beverages, tap water and perfume samples. The recoveries of the 16 PAEs from the real samples ranged from 64.6% to 125.6% with the RSDs less than 16.5%. Taken together, the MSPE-GC/MS method developed in current study provides a new option for the detection of PAEs from real samples with complex matrices. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Biomarker analysis of liver cells exposed to surfactant-wrapped and oxidized multi-walled carbon nanotubes (MWCNTs).

    PubMed

    Henderson, W Matthew; Bouchard, Dermont; Chang, Xiaojun; Al-Abed, Souhail R; Teng, Quincy

    2016-09-15

    Carbon nanotubes (CNTs) have great potential in industrial, consumer, and mechanical applications, based partly on their unique structural, optical and electronic properties. CNTs are commonly oxidized or treated with surfactants to facilitate aqueous solution processing, and these CNT surface modifications also increase possible human and ecological exposures to nanoparticle-contaminated waters. To determine the exposure outcomes of oxidized and surfactant-wrapped multiwalled carbon nanotubes (MWCNTs) on biochemical processes, metabolomics-based profiling of human liver cells (C3A) was utilized. Cells were exposed to 0, 10, or 100ng/mL of MWCNTs for 24 and 48h; MWCNT particle size distribution, charge, and aggregation were monitored concurrently during exposures. Following MWCNT exposure, cellular metabolites were extracted, lyophilized, and buffered for (1)H NMR analysis. Acquired spectra were subjected to both multivariate and univariate analysis to determine the consequences of nanotube exposure on the metabolite profile of C3A cells. Resulting scores plots illustrated temporal and dose-dependent metabolite responses to all MWCNTs tested. Loadings plots coupled with t-test filtered spectra identified metabolites of interest. XPS analysis revealed the presence of hydroxyl and carboxyl functionalities on both MWCNTs surfaces. Metal content analysis by ICP-AES indicated that the total mass concentration of the potentially toxic impurities in the exposure experiments were extremely low (i.e. [Ni]≤2×10(-10)g/mL). Preliminary data suggested that MWCNT exposure causes perturbations in biochemical processes involved in cellular oxidation as well as fluxes in amino acid metabolism and fatty acid synthesis. Dose-response trajectories were apparent and spectral peaks related to both dose and MWCNT dispersion methodologies were determined. Correlations of the significant changes in metabolites will help to identify potential biomarkers associated with carbonaceous

  17. Nonenzymatic electrochemical detection of glucose using well-distributed nickel nanoparticles on straight multi-walled carbon nanotubes.

    PubMed

    Nie, Huagui; Yao, Zhen; Zhou, Xuemei; Yang, Zhi; Huang, Shaoming

    2011-12-15

    A nonenzymatic electrochemical sensor device was fabricated for glucose detection based on nickel nanoparticles (NiNPs)/straight multi-walled carbon nanotubes (SMWNTs) nanohybrids, which were synthesized through in situ precipitation procedure. SMWNTs can be easily dispersed in solution after mild sonication pretreatment, which facilitates the precursor of NiNPs binding to their surface and results in the homogeneous distribution of NiNPs on the surface of SMWNTs. The morphology and component of the nanohybrids were characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD), respectively. Cyclic voltammetry (CV) and amperometry were used to evaluate the catalytic activity of the NiNPs/SMWNTs nanohybrids modified electrode towards glucose. It was found that the nanohybrids modified electrode showed remarkably enhanced electrocatalytic activity towards the oxidation of glucose in alkaline solution compared to that of the bare glass carbon electrode (GCE), the NiNPs and the SMWNTs modified electrode, attributing to the synergistic effect of SMWNTs and Ni(2+)/Ni(3+) redox couple. Under the optimal detection conditions, the as-prepared sensors exhibited linear behavior in the concentration range from 1 μM to 1 mM for the quantification of glucose with a limit of detection of 500 nM (3σ). Moreover, the NiNPs/SMWNTs modified electrode was also relatively insensitive to commonly interfering species such as ascorbic acid (AA), uric acid (UA), dopamine (DA), galactose (GA), and xylose (XY). The robust selectivities, sensitivities, and stabilities determined experimentally indicated the great potential of NiNPs/SMWNTs nanohybrids for construction of a variety of electrochemical sensors. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Nitrogen doped carbon derived from polyimide/multiwall carbon nanotube composites for high performance flexible all-solid-state supercapacitors

    NASA Astrophysics Data System (ADS)

    Kim, Dae Kyom; Kim, Nam Dong; Park, Seung-Keun; Seong, Kwang-dong; Hwang, Minsik; You, Nam-Ho; Piao, Yuanzhe

    2018-03-01

    Flexible all-solid-state supercapacitors are desirable as potential energy storage systems for wearable technologies. Herein, we synthesize aminophenyl multiwall carbon nanotube (AP-MWCNT) grafted polyimide precursor by in situ polymerization method as a nitrogen-doped carbon precursor. Flexible supercapacitor electrodes are fabricated via a coating of carbon precursor on carbon cloth surface and carbonization at high temperature directly. The as-obtained electrodes, which can be directly used without any binders or additives, can deliver a high specific capacitance of 333.4 F g-1 at 1 A g-1 (based on active material mass) and excellent cycle stability with 103% capacitance retention after 10,000 cycles in a three-electrode system. The flexible all-solid-state supercapacitor device exhibits a high volumetric capacitance of 3.88 F cm-3 at a current density of 0.02 mA cm-3. And also the device can deliver a maximum volumetric energy density of 0.50 mWh cm-3 and presents good cycling stability with 85.3% capacitance retention after 10,000 cycles. This device cell can not only show extraordinary mechanical flexibilities allowing folding, twisting, and rolling but also demonstrate remarkable stable electrochemical performances under their forms. This work provides a novel approach to obtain carbon textile-based flexible supercapacitors with high electrochemical performance and mechanical flexibility.

  19. The mechanical properties measurement of multiwall carbon nanotube reinforced nanocrystalline aluminum matrix composite

    SciTech Connect

    Sharma, Manjula, E-mail: manjula.physics@gmail.com; Pal, Hemant; Sharma, Vimal

    Nanocrystalline aluminum matrix composite containing carbon nanotubes were fabricated using physical mixing method followed by cold pressing. The microstructure of the composite has been investigated using X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy techniques. These studies revealed that the carbon nanotubes were homogeneously dispersed throughout the metal matrix. The consolidated samples were pressureless sintered in inert atmosphere to further actuate a strong interface between carbon nanotubes and aluminum matrix. The nanoindentation tests carried out on considered samples showed that with the addition of 0.5 wt% carbon nanotubes, the hardness and elastic modulus of the aluminum matrix increased bymore » 21.2 % and 2 % repectively. The scratch tests revealed a decrease in the friction coefficient of the carbon nanotubes reinforced composite due to the presence of lubricating interfacial layer. The prepared composites were promising entities to be used in the field of sporting goods, construction materials and automobile industries.« less

  20. The effect of ultrasonic processing of multi-wall carbon nanotubes on properties of elastomeric compositions on the basis of synthetic isoprene rubber

    NASA Astrophysics Data System (ADS)

    Mitryaeva, N. S.; Myshlyavtsev, A. V.; Akimenko, S. S.

    2017-08-01

    The paper studies the effect of ultrasonic processing on the vulcanizing, physical, mechanical and electrophysical properties of elastomeric compositions based on synthetic isoprene rubber. Microscopic studies of multi-wall carbon nanotubes samples before and after ultrasonic processing are carried out. Due to the research, the applied ultrasonic processing method provides splitting of bundles formed from multi-wall carbon nanotubes. This results in elastomeric material with increased strength and high electrical conductivity with a low concentration of nanofiller.

  1. Long-Term Effects of Multiwalled Carbon Nanotubes and Graphene on Microbial Communities in Dry Soil.

    PubMed

    Ge, Yuan; Priester, John H; Mortimer, Monika; Chang, Chong Hyun; Ji, Zhaoxia; Schimel, Joshua P; Holden, Patricia A

    2016-04-05

    Little is known about the long-term effects of engineered carbonaceous nanomaterials (ECNMs) on soil microbial communities, especially when compared to possible effects of natural or industrial carbonaceous materials. To address these issues, we exposed dry grassland soil for 1 year to 1 mg g(-1) of either natural nanostructured material (biochar), industrial carbon black, three types of multiwalled carbon nanotubes (MWCNTs), or graphene. Soil microbial biomass was assessed by substrate induced respiration and by extractable DNA. Bacterial and fungal communities were examined by terminal restriction fragment length polymorphism (T-RFLP). Microbial activity was assessed by soil basal respiration. At day 0, there was no treatment effect on soil DNA or T-RFLP profiles, indicating negligible interference between the amended materials and the methods for DNA extraction, quantification, and community analysis. After a 1-year exposure, compared to the no amendment control, some treatments reduced soil DNA (e.g., biochar, all three MWCNT types, and graphene; P < 0.05) and altered bacterial communities (e.g., biochar, carbon black, narrow MWCNTs, and graphene); however, there were no significant differences across the amended treatments. These findings suggest that ECNMs may moderately affect dry soil microbial communities but that the effects are similar to those from natural and industrial carbonaceous materials, even after 1-year exposure.

  2. Solid-contact pH-selective electrode using multi-walled carbon nanotubes.

    PubMed

    Crespo, Gastón A; Gugsa, Derese; Macho, Santiago; Rius, F Xavier

    2009-12-01

    Multi-walled carbon nanotubes (MWCNT) are shown to be efficient transducers of the ionic-to-electronic current. This enables the development of a new solid-contact pH-selective electrode that is based on the deposition of a 35-microm thick layer of MWCNT between the acrylic ion-selective membrane and the glassy carbon rod used as the electrical conductor. The ion-selective membrane was prepared by incorporating tridodecylamine as the ionophore, potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate as the lipophilic additive in a polymerized methylmethacrylate and an n-butyl acrylate matrix. The potentiometric response shows Nernstian behaviour and a linear dynamic range between 2.89 and 9.90 pH values. The response time for this electrode was less than 10 s throughout the whole working range. The electrode shows a high selectivity towards interfering ions. Electrochemical impedance spectroscopy and chronopotentiometry techniques were used to characterise the electrochemical behaviour and the stability of the carbon-nanotube-based ion-selective electrodes.

  3. Multiwall carbon nanotubes increase the microbial community in crude oil contaminated fresh water sediments.

    PubMed

    Abbasian, Firouz; Lockington, Robin; Palanisami, Thavamani; Megharaj, Mallavarapu; Naidu, Ravi

    2016-01-01

    Since crude oil contamination is one of the biggest environmental concerns, its removal from contaminated sites is of interest for both researchers and industries. In situ bioremediation is a promising technique for decreasing or even eliminating crude oil and hydrocarbon contamination. However, since these compounds are potentially toxic for many microorganisms, high loads of contamination can inhibit the microbial community and therefore reduce the removal rate. Therefore, any strategy with the ability to increase the microbial population in such circumstances can be of promise in improving the remediation process. In this study, multiwall carbon nanotubes were employed to support microbial growth in sediments contaminated with crude oil. Following spiking of fresh water sediments with different concentrations of crude oil alone and in a mixture with carbon nanotubes for 30days, the microbial profiles in these sediments were obtained using FLX-pyrosequencing. Next, the ratios of each member of the microbial population in these sediments were compared with those values in the untreated control sediment. This study showed that combination of crude oil and carbon nanotubes can increase the diversity of the total microbial population. Furthermore, these treatments could increase the ratios of several microorganisms that are known to be effective in the degradation of hydrocarbons. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Evaluation of the sorption mechanism of ionic liquids onto multi-walled carbon nanotubes.

    PubMed

    Wojsławski, Jerzy; Białk-Bielińska, Anna; Paszkiewicz, Monika; Toński, Michał; Stepnowski, Piotr; Dołżonek, Joanna

    2018-01-01

    The knowledge of the sorption mechanism of different chemicals onto third generation carbon sorbents such as carbon nanotubes (CNTs) is needed in order to project systems for the effective removal of pollutants from the environment. This paper reports evaluation of the sorption mechanism of selected ionic liquids (ILs), being considered as potential pollutant in environment, onto various CNTs. CNTs characterized by the smallest diameter and the biggest surface area showed the highest sorption capacity to isolate ILs from an aqueous solution. CNTs with a bigger diameter, a functionalized surface and particularly a helical shape showed a lower sorption capacity. The sorption mechanism has been defined as complex, including van der Waals, π-π and electrostatic interactions with dominating π-π interactions. Due to the relatively high sorption coefficient (355.98 ± 20.69-6397.10 ± 355.42 L kg -1 depending on the IL) the study showed that multi-walled carbon nanotubes can potentially be used to effectively isolate ILs from an aqueous solution. Moreover, proved in this study, the fast sorption kinetic, and uncomplicated regeneration process, leading to an even higher sorption capacity, means that CNTs are promising material which could find potential applications in the treatment of water contaminated by ILs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Carbon capture from natural gas using multi-walled CNTs based mixed matrix membranes.

    PubMed

    Hussain, Abid; Farrukh, Sarah; Hussain, Arshad; Ayoub, Muhammad

    2017-12-05

    Most of the polymers and their blends, utilized in carbon capture membranes, are costly, but cellulose acetate (CA) being inexpensive is a lucrative choice. In this research, pure and mixed matrix membranes (MMMs) have been fabricated to capture carbon from natural gas. Polyethylene glycol (PEG) has been utilized in the fabrication of membranes to modify the chain flexibility of polymers. Multi-walled carbon nanotubes (MWCNTs) provide mechanical strength, thermal stability, an extra free path for CO 2 molecules and augment CO 2 /CH 4 selectivity. Membranes of pure CA, CA/PEG blend of different PEG concentrations (5%, 10%, 15%) and CA/PEG/MWCNTs blend of 10% PEG with different MWCNTs concentrations (5%, 10%, 15%) were prepared in acetone using solution casting techniques. Fabricated membranes were characterized using SEM, TGA and tensile testing. Permeation results revealed remarkable improvement in CO 2 /CH 4 selectivity. In single gas experiments, CO 2 /CH 4 selectivity is enhanced 8 times for pure membranes containing 10% PEG and 14 times for MMMs containing 10% MWCNTs. In mix gas experiments, the CO 2 /CH 4 selectivity is increased 13 times for 10% PEG and 18 times for MMMs with 10% MWCNTs. Fabricated MMMs have a tensile strength of 13 MPa and are more thermally stable than CA membranes.

  6. Dexamethasone-Loaded, PEGylated, Vertically Aligned, Multiwalled Carbon Nanotubes for Potential Ischemic Stroke Intervention.

    PubMed

    Komane, Patrick P; Kumar, Pradeep; Marimuthu, Thashree; Toit, Lisa C du; Kondiah, Pierre P D; Choonara, Yahya E; Pillay, Viness

    2018-06-10

    The complete synthesis, optimization, purification, functionalization and evaluation of vertically aligned multiwalled carbon nanotubes (VA-MWCNTs) was reported for potential application in dexamethasone delivery to the ischemic brain tissue. The conditions for high yield were optimized and carbon nanotubes functionalized and PEGylated prior to dexamethasone loading. Morphological changes were confirmed by SEM and TEM. Addition of functional groups to MWCNTs was demonstrated by FTIR. Thermal stability reduced following MWCNTs functionalization as demonstrated in TGA. The presence of carbon at 2θ of 25° and iron at 2θ of 45° in MWCNTs was illustrated by XRD. Polydispersive index and zeta potential were found to be 0.261 and −15.0 mV, respectively. Dexamethasone release increased by 55%, 65% and 95% in pH of 7.4, 6.5 and 5.5 respectively as evaluated by UV-VIS. The functionalized VA-MWCNTs were demonstrated to be less toxic in PC-12 cells in the concentration range from 20 to 20,000 µg/mL. These findings have demonstrated the potential of VA-MWCNTs in the enhancement of fast and prolonged release of dexamethasone which could lead to the effective treatment of ischemic stroke. More work is under way for targeting ischemic sites using atrial natriuretic peptide antibody in stroke rats.

  7. Functionalization of multi-walled carbon nanotubes with thermo-responsive azide-terminated poly(N-isopropylacrylamide) via click reactions.

    PubMed

    Su, Xin; Shuai, Ya; Guo, Zanru; Feng, Yujun

    2013-04-18

    Covalently functionalized multi-walled carbon nanotubes (MWNTs) were prepared by grafting well-defined thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) via click reactions. First, azide-terminated poly(N-isopropylacrylamide) (N3-PNIPAM) was synthesized by reversible addition fragmentation chain-transfer (RAFT) polymerization, and then the N₃-PNIPAM moiety was connected onto MWNTs by click chemistry. The products were characterized by means of FT-IR, TGA and TEM. The results show that the modification of MWNTs is very successful and MWNTs functionalized by N₃-PNIPAM (MWNTs-PNIPAM) have good solubility and stability in water. TEM images show the functionalized MWNTs are dispersed individually, indicating that the bundles of original MWNTs are separated into individual tubes by surface modification with polymer chains. These MWNTs modified with PNIPAM represent a potential nano-material for preparation of hydrophilic composite materials.

  8. FTIR spectroscopy of multiwalled carbon nanotubes: a simple approach to study the nitrogen doping.

    PubMed

    Misra, Abha; Tyagi, Pawan K; Rai, Padmnabh; Misra, D S

    2007-06-01

    The nitrogen doped multiwalled carbon nanotubes (MWNTs) were synthesized by microwave plasma chemical vapor deposition (MPCVD) technique. In this paper, we report the results of FTIR, Raman, and TGA studies to confirm the presence of N-doping inside carbon nanotubes. Fourier transform infrared (FTIR) studies were carried out in the range 400-4000 cm(-1) to study the attachment of nitrogen impurities on carbon nanotubes. FTIR spectra of the virgin sample of MWNTs show dominant peaks which are corresponding to Si-O, C-N, N-CH3, CNT, C-O, and C-Hx, respectively. The Si-O peak has its origin in silicon substrate whereas the other peaks are due to the precursor gases present in the gas mixture. The peaks are sharp and highly intense showing the chemisorption nature of the dipole bond. The intensity of the peaks due to N-CH3, C-N, and C-H reduces after annealing. It is interesting to note that these peaks vanish on annealing at high temperature (900 degrees C). The presence of C-N peak may imply the doping of the MWNTs with N in substitution mode. The position of this intense peak is in agreement with the reported peak in carbon nitride samples prepared by plasma CVD process, since the Raman modes are also expected to be delocalized over both carbon and nitrogen sites it was found that the intensity ratio of the D and G peaks, I(D)/I(G), varies as a function of ammonia concentration. The TGA measurements, carried out under argon flow, show that the dominant weight loss of the sample occurs in the temperature range 400-600 degrees C corresponding to the removal of the impurities and amorphous carbon.

  9. Genotoxicity of multi-walled carbon nanotubes at occupationally relevant doses

    PubMed Central

    2014-01-01

    Carbon nanotubes are commercially-important products of nanotechnology; however, their low density and small size makes carbon nanotube respiratory exposures likely during their production or processing. We have previously shown mitotic spindle aberrations in cultured primary and immortalized human airway epithelial cells exposed to single-walled carbon nanotubes (SWCNT). In this study, we examined whether multi-walled carbon nanotubes (MWCNT) cause mitotic spindle damage in cultured cells at doses equivalent to 34 years of exposure at the NIOSH Recommended Exposure Limit (REL). MWCNT induced a dose responsive increase in disrupted centrosomes, abnormal mitotic spindles and aneuploid chromosome number 24 hours after exposure to 0.024, 0.24, 2.4 and 24 μg/cm2 MWCNT. Monopolar mitotic spindles comprised 95% of disrupted mitoses. Three-dimensional reconstructions of 0.1 μm optical sections showed carbon nanotubes integrated with microtubules, DNA and within the centrosome structure. Cell cycle analysis demonstrated a greater number of cells in S-phase and fewer cells in the G2 phase in MWCNT-treated compared to diluent control, indicating a G1/S block in the cell cycle. The monopolar phenotype of the disrupted mitotic spindles and the G1/S block in the cell cycle is in sharp contrast to the multi-polar spindle and G2 block in the cell cycle previously observed following exposure to SWCNT. One month following exposure to MWCNT there was a dramatic increase in both size and number of colonies compared to diluent control cultures, indicating a potential to pass the genetic damage to daughter cells. Our results demonstrate significant disruption of the mitotic spindle by MWCNT at occupationally relevant exposure levels. PMID:24479647

  10. Anomalous thermal hysteresis in the high-field magnetic moments of magnetic nanoparticles embedded in multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhao, Guo-Meng; Wang, Jun; Ren, Yang; Beeli, Pieder

    2012-02-01

    We report high-temperature (300-1120 K) magnetic properties of Fe and Fe3O4 nanoparticles embedded in multi-walled carbon nanotubes. We unambiguously show that the magnetic moments of Fe and Fe3O4 nanoparticles are seemingly enhanced by a factor of about 3 compared with what they would be expected to have for free (unembedded) magnetic nanoparticles. What is more intriguing is that the enhanced moments were completely lost when the sample was heated up to 1120 K and the lost moments at 1120 K were completely recovered through several thermal cycles below 1020 K. The anomalous thermal hysteresis of the high-field magnetic moments is unlikely to be explained by existing physical models except for the high-field paramagnetic Meissner effect due to the existence of ultrahigh temperature superconductivity in the multi-walled carbon nanotubes.

  11. Linear free energy relationships for the adsorption of volatile organic compounds onto multiwalled carbon nanotubes at different relative humidities: comparison with organoclays and activated carbon.

    PubMed

    Li, Mei-Syue; Wang, Reuben; Fu Kuo, Dave Ta; Shih, Yang-Hsin

    2017-03-22

    Accurate prediction of the sorption coefficients of volatile organic compounds (VOCs) on carbon nanotubes (CNTs) is of major importance for developing an effective VOC removal process and risk assessment of released nanomaterial-carrying contaminants. The linear free energy relationship (LFER) approach was applied to investigate the adsorption mechanisms of VOCs on multiwalled CNTs (MWCNTs). The gas-solid partition coefficients (log K d ) of 17 VOCs were determined at 0%, 55%, and 90% relative humidity (RH). The cavity/dispersion interaction is generally the most influential adsorption mechanism for all RH cases. The hydrogen-accepting interactions declined but with constant hydrogen-donating interactions during the increase of RH, suggesting that the acidity of VOC was important in forming sorptive interaction with the MWCNT surface. Moreover, the comparison of log K d of VOCs on MWCNTs and other sorbents revealed that the sorption performance of MWCNTs is much more stable over a wider range of RHs due to better site availability and site quality. Furthermore, for all 6 adsorbents in all RHs, the positive contribution of hydrogen bonding ability was found as compared to the negative one found for sorbents completely in water, indicating that the hydrogen-bond donor and acceptor on the sorbent surface contribute to the sorption in the gas phase. In conclusion, the LFER-derived coefficients can be useful in predicting the performance of VOC adsorption on adsorbents and in facilitating the design of efficient VOC removal systems.

  12. Molecular Dynamics Simulation of a Multi-Walled Carbon Nanotube Based Gear

    NASA Technical Reports Server (NTRS)

    Han, Jie; Globus, Al; Srivastava, Deepak; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    We used molecular dynamics to investigate the properties of a multi-walled carbon nanotube based gear. Previous work computationally suggested that molecular gears fashioned from (14,0) single-walled carbon nanotubes operate well at 50-100 gigahertz. The gears were formed from nanotubes with teeth added via a benzyne reaction known to occur with C60. A modified, parallelized version of Brenner's potential was used to model interatomic forces within each molecule. A Leonard-Jones 6-12 potential was used for forces between molecules. The gear in this study was based on the smallest multi-walled nanotube supported by some experimental evidence. Each gear was a (52,0) nanotube surrounding a (37,10) nanotube with approximate 20.4 and 16,8 A radii respectively. These sizes were chosen to be consistent with inter-tube spacing observed by and were slightly larger than graphite inter-layer spacings. The benzyne teeth were attached via 2+4 cycloaddition to exterior of the (52,0) tube. 2+4 bonds were used rather than the 2+2 bonds observed by Hoke since 2+4 bonds are preferred by naphthalene and quantum calculations by Jaffe suggest that 2+4 bonds are preferred on carbon nanotubes of sufficient diameter. One gear was 'powered' by forcing the atoms near the end of the outside buckytube to rotate to simulate a motor. A second gear was allowed to rotate by keeping the atoms near the end of its outside buckytube on a cylinder. The ends of both gears were constrained to stay in an approximately constant position relative to each other, simulating a casing, to insure that the gear teeth meshed. The stiff meshing aromatic gear teeth transferred angular momentum from the powered gear to the driven gear. The simulation was performed in a vacuum and with a software thermostat. Preliminary results suggest that the powered gear had trouble turning the driven gear without slip. The larger radius and greater mass of these gears relative to the (14,0) gears previously studied requires a

  13. Extraction of ochratoxin A in red wine with dopamine-coated magnetic multi-walled carbon nanotubes.

    PubMed

    Wan, Hong; Zhang, Bo; Bai, Xiao-Lin; Zhao, Yan; Xiao, Meng-Wei; Liao, Xun

    2017-10-01

    A new, rapid, green, and cost-effective magnetic solid-phase extraction of ochratoxin A from red wine samples was developed using polydopamine-coated magnetic multi-walled carbon nanotubes as the absorbent. The polydopamine-coated magnetic multi-walled carbon nanotubes were fabricated with magnetic multi-walled carbon nanotubes and dopamine by an in situ oxidative self-polymerization approach. Transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy and vibrating sample magnetometry were used to characterize the absorbents. Ochratoxin A was quantified with high-performance liquid chromatography coupled with fluorescence detection, with excitation and emission wavelengths of 338 and 455 nm, respectively. The conditions affecting the magnetic solid-phase extraction procedure, such as pH, extraction solution, extraction time, absorbent amount, desorption solution and desorption time were investigated to obtain the optimal extraction conditions. Under the optimized conditions, the extraction recovery was 91.8-104.5% for ochratoxin A. A linear calibration curve was obtained in the range of 0.1-2.0 ng/mL. The limit of detection was 0.07 ng/mL, and the limit of quantitation was 0.21 ng/mL. The recoveries of ochratoxin A for spiked red wine sample ranged from 95.65 to 100.65% with relative standard deviation less than 8%. The polydopamine-coated magnetic multi-walled carbon nanotubes showed a high affinity toward ochratoxin A, allowing selective extraction and quantification of ochratoxin A from complex sample matrixes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Polyvinyl alcohol (PVA)-cellulose nanofibril (CNF)-multiwalled carbon nanotube (MWCNT) hybrid organic aerogels with superior mechanical properties

    Treesearch

    Qifeng Zheng; Alireza Javadi; Ronald Sabo; Zhiyong Cai; Shaoqin Gong

    2013-01-01

    Polyvinyl alcohol (PVA)–cellulose nanofibril (CNF)–multiwalled carbon nanotube (MWCNT) hybrid organic aerogels were prepared using an environmentally friendly freeze-drying process with renewable materials. The material properties of these “green” hybrid aerogels were characterized extensively using various techniques. It was found that adding a small amount of CNFs...

  15. Linear strain sensor made of multi-walled carbon nanotube/epoxy composite

    NASA Astrophysics Data System (ADS)

    Tong, Shuying; Yuan, Weifeng; Liu, Haidong; Alamusi; Hu, Ning; Zhao, Chaoyang; Zhao, Yangzhou

    2017-11-01

    In this study, a fabrication process was developed to make the multi-walled carbon nanotubes/epoxy (MWCNT/EP) composite films. The electrical-strain behaviour of the films in direct and alternating current circuits were both tested. It is found that the direct current resistance and the dielectric loss tangent of the MWCNT/EP composite films are dependent on the strain and the weight fraction of the carbon nanotubes. In an alternating current circuit, the test frequency affects the impedance and the phase angle of the composite film, but it has nothing to do with the change ratio of the dielectric loss tangent of the film in tension. This phenomenon can be interpreted by a proposed equivalent circuit model. Experiment results show that the change rate of the dielectric loss tangent of the MWCNT/EP sensor is linearly proportional to the strain. The findings obtained in the present study provide a promising method to develop ultrasensitive linear strain gauges.

  16. Influence of surface oxides on the adsorption of naphthalene onto multiwalled carbon nanotubes.

    PubMed

    Cho, Hyun-Hee; Smith, Billy A; Wnuk, Joshua D; Fairbrother, D Howard; Ball, William P

    2008-04-15

    As greater quantities of carbon nanotubes (CNTs) enter the environment, they will have an increasingly important effect on the availability and transport of aqueous contaminants. As a consequence of purification, deliberate surface functionalization, and/or exposure to oxidizing agents after release to the environment, CNTs often contain surface oxides (i.e., oxygen containing functional groups). To probe the influence that surface oxides exert on CNT sorption properties, multiwalled CNTs (MWCNTs) with varying oxygen concentrations were studied with respect to their sorption properties toward naphthalene. For pristine (as-received) MWCNTs, the sorption capacity was intermediate between that of a natural char and a granular activated carbon. Sorption data also reveal that a linear relationship exists between the oxygen content of MWCNTs and their maximum adsorption capacity for naphthalene, with 10% surface oxygen concentration resulting in a roughly 70% decrease in maximum adsorption capacity. The relative distribution of sorption energies, as characterized by Freundlich isotherm exponents was, however, unaffected by oxidation. Thus, the data are consistent with the idea that incorporated surface oxides create polar regions that reduce the surface area available for naphthalene sorption. These results highlight the important role of surface chemistry in controlling the environmental properties of CNTs.

  17. Decoration of gold nanoparticles on thin multiwall carbon nanotubes and their use as a glucose sensor

    NASA Astrophysics Data System (ADS)

    Gangwar, Rajesh K.; Dhumale, Vinayak A.; Date, Kalyani S.; Alegaonkar, Prashant; Sharma, Rishi B.; Datar, Suwarna

    2016-03-01

    Thin multiwall carbon nanotubes (MWCNTs) have been decorated with gold nanoparticles (Au NPs) with polyaniline (PANI) as an inter-linker by a simple wet chemical method. The synthesized AuNPs:MWCNT:PANI composite was studied with UV-vis, FTIR, Raman spectroscopy, x-ray diffractometer, transmission electron microscopy (TEM) and atomic force microscopy (AFM). Conducting AFM (C-AFM) images of the composite reveal the role played by the two components in electrochemical reactions. The size of the Au NPs was found to be 13 ± 2 nm in the composite as observed from TEM. The synthesized AuNPs:MWCNT:PANI composite was further drop casted onto a glassy carbon electrode (GCE) for electrocatalytic study. The resulting composite exhibits good electrocatalytic activity towards reduction of H2O2 and O2. A glucose biosensor was developed by immobilizing glucose oxidase into AuNPs:MWCNT:PANI composite film on GCE. The fabricated sensor demonstrates good linear response to glucose (i.e. R = 0.9975) in the range of 2 to 12 mM.

  18. Chronocoulometry of wine on multi-walled carbon nanotube modified electrode: Antioxidant capacity assay.

    PubMed

    Ziyatdinova, Guzel; Kozlova, Ekaterina; Budnikov, Herman

    2016-04-01

    Phenolic antioxidants of wine were electrochemically oxidized on multi-walled carbon nanotubes modified glassy carbon electrode (MWNT/GCE) in phosphate buffer solution. Three oxidation peaks were observed at 0.39, 0.61 and 0.83V for red dry wine and 0.39, 0.80 and 1.18 V for white dry wine, respectively, using differential pulse voltammetry at pH 4.0. The oxidation potentials for individual phenolic antioxidants confirmed the integral nature of the analytical signals for the wines examined. A one-step chronocoulometric method at 0.83 and 1.18 V for red and white wines, respectively, has been developed for the evaluation of wine antioxidant capacity (AOC). The AOC is expressed in gallic acid equivalents per 1L of wine. The AOC of white wine was significantly less than red wine (386 ± 112 vs. 1224 ± 184, p<0.0001), as might be expected. Positive correlations were observed between gallic acid equivalent AOC of wine and total antioxidant capacity, based on coulometric titration with electrogenerated bromine (r=0.8957 at n=5 and r=0.8986 at n=4 for red and white wines, respectively). Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Magnetic MoS2 on multiwalled carbon nanotubes for sulfide sensing.

    PubMed

    Li, Chunxiang; Zhang, Dan; Wang, Jiankang; Hu, Pingan; Jiang, Zhaohua

    2017-07-04

    A novel hybrid metallic cobalt insided in multiwalled carbon nanotubles/molybdenum disulfide (Co@CNT/MoS 2 ) modified glass carbon electrode (GCE) was fabricated with a adhesive of Nafion suspension and used as chemical sensors for sulfide detection. Single-layered MoS 2 was coated on CNTs through magnetic traction force between paramagnetic monolayer MoS 2 and Co particles in CNTs. Co particles faciliated the collection of paramagnetic monolayer MoS 2 exfoliated from bulk MoS 2 in solution. Amperometric analysis, cycle voltammetry, cathodic stripping analysis and linear sweep voltammetry results showed the Co@CNT/MoS 2 modified GCE exhibited excellent electrochemical activity to sulfide in buffer solutions, but amperometric analysis was found to be more sensitive than the other methods. The amperometric response result indicated the Co@CNT/MoS 2 -modified GCE electrode was an excellent electrochemical sensor for detecting S 2- with a detection limit of 7.6 nM and sensitivity of 0.23 mA/μM. The proposed electrode was used for the determination of sulfide levels in hydrogen sulfide-pretreated fruits, and the method was also verified with recovery studies. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    PubMed

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

    2009-02-04

    Multiwall carbon nanotubes (MWCNTs) possessing an average inner diameter of 150 nm were synthesized by template assisted chemical vapor deposition over an alumina template. Aqueous ferrofluid based on superparamagnetic iron oxide nanoparticles (SPIONs) was prepared by a controlled co-precipitation technique, and this ferrofluid was used to fill the MWCNTs by nanocapillarity. The filling of nanotubes with iron oxide nanoparticles was confirmed by electron microscopy. Selected area electron diffraction indicated the presence of iron oxide and graphitic carbon from MWCNTs. The magnetic phase transition during cooling of the MWCNT-SPION composite was investigated by low temperature magnetization studies and zero field cooled (ZFC) and field cooled experiments. The ZFC curve exhibited a blocking at approximately 110 K. A peculiar ferromagnetic ordering exhibited by the MWCNT-SPION composite above room temperature is because of the ferromagnetic interaction emanating from the clustering of superparamagnetic particles in the constrained volume of an MWCNT. This kind of MWCNT-SPION composite can be envisaged as a good agent for various biomedical applications.

  1. Electrical and Raman spectroscopic studies of vertically aligned multi-walled carbon nanotubes.

    PubMed

    Mathur, Ashish; Tweedie, Mark; Roy, Susanta Sinha; Maguire, P D; McLaughlin, James A

    2009-07-01

    Microwave plasma enhanced chemical vapour deposition (MPECVD) was used for the production of carbon nanotubes. Vertically aligned multi-walled carbon nanotubes (MWCNTs) were grown on silicon substrates coated with cobalt thin films of thickness ranging from 0.5 nm to 3 nm. Prior to the nanotube growth the catalyst were treated with N2 plasma for 5-10 minutes that break the films into small nanoparticles which favour the growth of nanotubes. The CNTs were grown at a substrate temperature of 700 degrees C for 5, 10 and 15 minutes. The height of the CNT films ranging from 10 microm-30 microm indicating that the initial growth rate of the CNTs are very high at a rate of approximately 100 nm/sec. Electrical resistivity of the above samples was evaluated from I-V measurements. The activation energy (E(a)) was also calculated from the temperature dependent studies and it was found that the E(a) lies in the range of 15-35 meV. Raman spectroscopy was used to identify the quality of the nanotubes.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  3. Selective ex-vivo photothermal ablation of human pancreatic cancer with albumin functionalized multiwalled carbon nanotubes

    PubMed Central

    Mocan, Lucian; Tabaran, Flaviu A; Mocan, Teodora; Bele, Constantin; Orza, Anamaria Ioana; Lucan, Ciprian; Stiufiuc, Rares; Manaila, Ioana; Iulia, Ferencz; Dana, Iancu; Zaharie, Florin; Osian, Gelu; Vlad, Liviu; Iancu, Cornel

    2011-01-01

    The process of laser-mediated ablation of cancer cells marked with biofunctionalized carbon nanotubes is frequently called “nanophotothermolysis”. We herein present a method of selective nanophotothermolisys of pancreatic cancer (PC) using multiwalled carbon nanotubes (MWCNTs) functionalized with human serum albumin (HSA). With the purpose of testing the therapeutic value of these nanobioconjugates, we have developed an ex-vivo experimental platform. Surgically resected specimens from patients with PC were preserved in a cold medium and kept alive via intra-arterial perfusion. Additionally, the HSA-MWCNTs have been intra-arterially administered in the greater pancreatic artery under ultrasound guidance. Confocal and transmission electron microscopy combined with immunohistochemical staining have confirmed the selective accumulation of HSA-MWCNTs inside the human PC tissue. The external laser irradiation of the specimen has significantly produced extensive necrosis of the malign tissue after the intra-arterial administration of HSA-MWCNTs, without any harmful effects on the surrounding healthy parenchyma. We have obtained a selective photothermal ablation of the malign tissue based on the selective internalization of MWCNTs with HSA cargo inside the pancreatic adenocarcinoma after the ex-vivo intra-arterial perfusion. PMID:21720504

  4. Selective ex-vivo photothermal ablation of human pancreatic cancer with albumin functionalized multiwalled carbon nanotubes.

    PubMed

    Mocan, Lucian; Tabaran, Flaviu A; Mocan, Teodora; Bele, Constantin; Orza, Anamaria Ioana; Lucan, Ciprian; Stiufiuc, Rares; Manaila, Ioana; Iulia, Ferencz; Dana, Iancu; Zaharie, Florin; Osian, Gelu; Vlad, Liviu; Iancu, Cornel

    2011-01-01

    The process of laser-mediated ablation of cancer cells marked with biofunctionalized carbon nanotubes is frequently called "nanophotothermolysis". We herein present a method of selective nanophotothermolisys of pancreatic cancer (PC) using multiwalled carbon nanotubes (MWCNTs) functionalized with human serum albumin (HSA). With the purpose of testing the therapeutic value of these nanobioconjugates, we have developed an ex-vivo experimental platform. Surgically resected specimens from patients with PC were preserved in a cold medium and kept alive via intra-arterial perfusion. Additionally, the HSA-MWCNTs have been intra-arterially administered in the greater pancreatic artery under ultrasound guidance. Confocal and transmission electron microscopy combined with immunohistochemical staining have confirmed the selective accumulation of HSA-MWCNTs inside the human PC tissue. The external laser irradiation of the specimen has significantly produced extensive necrosis of the malign tissue after the intra-arterial administration of HSA-MWCNTs, without any harmful effects on the surrounding healthy parenchyma. We have obtained a selective photothermal ablation of the malign tissue based on the selective internalization of MWCNTs with HSA cargo inside the pancreatic adenocarcinoma after the ex-vivo intra-arterial perfusion.

  5. Individual and competitive adsorption of phenol and nickel onto multiwalled carbon nanotubes

    PubMed Central

    Abdel-Ghani, Nour T.; El-Chaghaby, Ghadir A.; Helal, Farag S.

    2014-01-01

    Individual and competitive adsorption studies were carried out to investigate the removal of phenol and nickel ions by adsorption onto multiwalled carbon nanotubes (MWCNTs). The carbon nanotubes were characterized by different techniques such as X-ray diffraction, scanning electron microscopy, thermal analysis and Fourier transformation infrared spectroscopy. The different experimental conditions affecting the adsorption process were investigated. Kinetics and equilibrium models were tested for fitting the adsorption experimental data. The characterization experimental results proved that the studied adsorbent possess different surface functional groups as well as typical morphological features. The batch experiments revealed that 300 min of contact time was enough to achieve equilibrium for the adsorption of both phenol and nickel at an initial adsorbate concentration of 25 mg/l, an adsorbent dosage of 5 g/l, and a solution pH of 7. The adsorption of phenol and nickel by MWCNTs followed the pseudo-second order kinetic model and the intraparticle diffusion model was quite good in describing the adsorption mechanism. The Langmuir equilibrium model fitted well the experimental data indicating the homogeneity of the adsorbent surface sites. The maximum Langmuir adsorption capacities were found to be 32.23 and 6.09 mg/g, for phenol and Ni ions, respectively. The removal efficiency of MWCNTs for nickel ions or phenol in real wastewater samples at the optimum conditions reached up to 60% and 70%, respectively. PMID:26257938

  6. Multiwalled carbon nanotubes enter broccoli cells enhancing growth and water uptake of plants exposed to salinity.

    PubMed

    Martínez-Ballesta, M Carmen; Zapata, Lavinia; Chalbi, Najla; Carvajal, Micaela

    2016-06-08

    Carbon nanotubes have been shown to improve the germination and growth of some plant species, extending the applicability of the emerging nano-biotechnology field to crop science. In this work, exploitation of commercial multiwalled carbon nanotubes (MWCNTs) in control and 100 mM NaCl-treated broccoli was performed. Transmission electron microscopy demonstrated that MWCNTs can enter the cells in adult plants with higher accumulation under salt stress. Positive effect of MWCNTs on growth in NaCl-treated plants was consequence of increased water uptake, promoted by more-favourable energetic forces driving this process, and enhanced net assimilation of CO2. MWCNTs induced changes in the lipid composition, rigidity and permeability of the root plasma membranes relative to salt-stressed plants. Also, enhanced aquaporin transduction occurred, which improved water uptake and transport, alleviating the negative effects of salt stress. Our work provides new evidences about the effect of MWCNTs on plasma membrane properties of the plant cell. The positive response to MWCNTs in broccoli plants opens novel perspectives for their technological uses in new agricultural practices, especially when 1plants are exposed to saline environments.

  7. Electrical and dielectric properties of foam injection-molded polypropylene/multiwalled carbon nanotube composites

    SciTech Connect

    Ameli, A.; Nofar, M.; Saniei, M.

    A combination of high dielectric permittivity (ε′) and low dielectric loss (tan δ) is required for charge storage applications. In percolative systems such as conductive polymer composites, however, obtaining high ε′ and low tan δ is very challenging due to the sharp insulation-conduction transition near the threshold region. Due to the particular arrangement of conductive fillers induced by both foaming and injection molding processes, they may address this issue. Therefore, this work evaluates the application of foam injection molding process in fabricating polymer nanocomposites for energy storage. Polypropylene-multiwalled carbon nanotubes (PP-MWCNT) composites were prepared by melt mixing and foamed inmore » an injection molding process. Electrical conductivity (σ), ε′ and tan δ were then characterized. Also, scanning and transmission electron microscopy (SEM and TEM) was used to investigate the carbon nanotube’s arrangement as well as cellular morphology. The results showed that foam injection-molded composites exhibited highly superior dielectric properties to those of solid counterparts. For instance, foamed samples had ε′=68.3 and tan δ =0.05 (at 1.25 vol.% MWCNT), as opposed to ε′=17.8 and tan δ=0.04 in solid samples (at 2.56 vol.% MWCNT). The results of this work reveal that high performance dielectric nanocomposites can be developed using foam injection molding technologies for charge storage applications.« less

  8. Laser-induced selective metallization of polypropylene doped with multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ratautas, Karolis; Gedvilas, Mindaugas; Stankevičiene, Ina; Jagminienė, Aldona; Norkus, Eugenijus; Pira, Nello Li; Sinopoli, Stefano; Račiukaitis, Gediminas

    2017-08-01

    Moulded interconnect devices (MID) offer the material, weight and cost saving by integration electronic circuits directly into polymeric components used in automotive and other consumer products. Lasers are used to write circuits directly by modifying the surface of polymers followed by an electroless metal plating. A new composite material - the polypropylene doped with multiwall carbon nanotubes was developed for the laser-induced selective metallization. Mechanism of surface activation by laser irradiation was investigated in details utilising pico- and nanoseconds lasers. Deposition of copper was performed in the autocatalytic electroless plating bath. The laser-activated polymer surfaces have been studied using the Raman spectroscopy and scanning electron microscope (SEM). Microscopic images revealed that surface becomes active only after its melting by a laser. Alterations in the Raman spectra of the D and G bands indicated the clustering of carbon additives in the composite material. Optimal laser parameters for the surface activation were found by measuring a sheet resistance of the finally metal-plated samples. A spatially selective copper plating was achieved with the smallest conductor line width of 22 μm at the laser scanning speed of 3 m/s and the pulse repetition rate of 100 kHz. Finally, the technique was validated by making functional electronic circuits by this MID approach.

  9. Characterization of functionalized multiwalled carbon nanotubes for use in an enzymatic sensor.

    PubMed

    Guadarrama-Fernández, Leonor; Chanona-Pérez, Jorge; Manzo-Robledo, Arturo; Calderón-Domínguez, Georgina; Martínez-Rivas, Adrián; Ortiz-López, Jaime; Vargas-García, Jorge Roberto

    2014-10-01

    Carbon nanotubes (CNT) have proven to be materials with great potential for the construction of biosensors. Development of fast, simple, and low cost biosensors to follow reactions in bioprocesses, or to detect food contaminants such as toxins, chemical compounds, and microorganisms, is presently an important research topic. This report includes microscopy and spectroscopy to characterize raw and chemically modified multiwall carbon nanotubes (MWCNTs) synthesized by chemical vapor deposition with the intention of using them as the active transducer in bioprocessing sensors. MWCNT were simultaneously purified and functionalized by an acid mixture involving HNO3-H2SO4 and amyloglucosidase attached onto the chemically modified MWCNT surface. A 49.0% decrease in its enzymatic activity was observed. Raw, purified, and enzyme-modified MWCNTs were analyzed by scanning and transmission electron microscopy and Raman and X-ray photoelectron spectroscopy. These studies confirmed purification and functionalization of the CNTs. Finally, cyclic voltammetry electrochemistry was used for electrical characterization of CNTs, which showed promising results that can be useful for construction of electrochemical biosensors applied to biological areas.

  10. Measurements of near-ultimate strength for multiwalled carbon nanotubes and irradiation-induced crosslinking improvements.

    PubMed

    Peng, Bei; Locascio, Mark; Zapol, Peter; Li, Shuyou; Mielke, Steven L; Schatz, George C; Espinosa, Horacio D

    2008-10-01

    The excellent mechanical properties of carbon nanotubes are being exploited in a growing number of applications from ballistic armour to nanoelectronics. However, measurements of these properties have not achieved the values predicted by theory due to a combination of artifacts introduced during sample preparation and inadequate measurements. Here we report multiwalled carbon nanotubes with a mean fracture strength >100 GPa, which exceeds earlier observations by a factor of approximately three. These results are in excellent agreement with quantum-mechanical estimates for nanotubes containing only an occasional vacancy defect, and are approximately 80% of the values expected for defect-free tubes. This performance is made possible by omitting chemical treatments from the sample preparation process, thus avoiding the formation of defects. High-resolution imaging was used to directly determine the number of fractured shells and the chirality of the outer shell. Electron irradiation at 200 keV for 10, 100 and 1,800 s led to improvements in the maximum sustainable loads by factors of 2.4, 7.9 and 11.6 compared with non-irradiated samples of similar diameter. This effect is attributed to crosslinking between the shells. Computer simulations also illustrate the effects of various irradiation-induced crosslinking defects on load sharing between the shells.

  11. Third Sound Generation in Superfluid 4He Films Adsorbed on Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Iaia, Vito; Menachekanian, Emin; Williams, Gary

    2014-03-01

    A technique is developed for generating third sound in superfluid 4He films coating the surface of multiwall carbon nanotubes. Third sound is a thickness and temperature wave of the helium film, and in our case we detect the temperature oscillations with a carbon resistance bolometer. The nanotubes are packed in an annular resonator that is vibrated with a mechanical shaker assembly consisting of a permanent magnet mounted on springs, and surrounded by a superconducting coil. The coil is driven with an oscillating current, vibrating the cell at that frequency. Sweeping the drive frequency over the range 100-200 Hz excites the resonant third sound mode of the cell, seen as a high-Q signal in the FFT analysis of the bolometer signal. A problem with our original cell was that the mechanical drive would also shake the dilution refrigerator cooling the cell to low temperatures, and increasing the drive would start to heat up the refrigerator and the cell, which were rigidly coupled together. A new configuration now suspends the cell as a pendulum on a string, with thermal contact made by copper wires. Piezo sensor measurements show this reduces the vibration reaching the refrigerator by two orders of magnitude, which should allow measurements at lower temperatures.

  12. Tuning vertical alignment and field emission properties of multi-walled carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Sreekanth, M.; Ghosh, S.; Srivastava, P.

    2018-01-01

    We report the growth of vertically aligned carbon nanotube bundles on Si substrate by thermal chemical vapor deposition technique. Vertical alignment was achieved without any carrier gas or lithography-assisted deposition. Growth has been carried out at 850 °C for different quantities of solution of xylene and ferrocene ranging from 2.25 to 3.00 ml in steps of 0.25 ml at a fixed concentration of 0.02 gm (ferrocene) per ml. To understand the growth mechanism, deposition was carried out for different concentrations of the solution by changing only the ferrocene quantity, ranging from 0.01 to 0.03 gm/ml. A tunable vertical alignment of multi-walled carbon nanotubes (CNTs) has been achieved by this process and examined by scanning and transmission electron microscopic techniques. Micro-crystalline structural analysis has been done using Raman spectroscopy. A systematic variation in field emission (FE) current density has been observed. The highest FE current density is seen for the film grown with 0.02 gm/ml concentration, which is attributed to the better alignment of CNTs, less structural disorder and less entanglement of CNTs on the surface. The alignment of CNTs has been qualitatively understood on the basis of self-assembled catalytic particles.

  13. Heat transfer nanofluid based on curly ultra-long multi-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Boncel, Sławomir; Zniszczoł, Aurelia; Pawlyta, Mirosława; Labisz, Krzysztof; Dzido, Grzegorz

    2018-02-01

    The main challenge in the use of multi-wall carbon nanotube (MWCNT) as key components of nanofluids is to transfer excellent thermal properties from individual nanotubes into the bulk systems. We present studies on the performance of heat transfer nanofluids based on ultra-long ( 2 mm), curly MWCNTs - in the background of various other nanoC-sp2, i.e. oxidized MWCNTs, commercially available Nanocyl™ MWCNTs and spherical carbon nanoparticles (SCNs). The nanofluids prepared via ultrasonication from water and propylene glycol were studied in terms of heat conductivity and heat transfer in a scaled up thermal circuit containing a copper helical heat exchanger. Ultra-long curly MWCNT (1 wt.%) nanofluids (stabilized with Gum Arabic in water) emerged as the most thermally conducting ones with a 23-30%- and 39%-enhancement as compared to the base-fluids for water and propylene glycol, respectively. For turbulent flows ( Re = 8000-11,000), the increase of heat transfer coefficient for the over-months stable 1 wt.% ultra-long MWCNT nanofluid was found as high as >100%. The findings allow to confirm that longer MWCNTs are promising solid components in nanofluids and hence to predict their broader application in heat transfer media.

  14. Measurements of near-ultimate strength for multiwalled carbon nanotubes and irradiation-induced crosslinking improvements.

    SciTech Connect

    Peng, B.; Locascio, M.; Zapol, P.

    2008-01-01

    The excellent mechanical properties of carbon nanotubes are being exploited in a growing number of applications from ballistic armour to nanoelectronics. However, measurements of these properties have not achieved the values predicted by theory due to a combination of artifacts introduced during sample preparation and inadequate measurements. Here we report multiwalled carbon nanotubes with a mean fracture strength >100 GPa, which exceeds earlier observations by a factor of approximately three. These results are in excellent agreement with quantum-mechanical estimates for nanotubes containing only an occasional vacancy defect, and are {approx}80% of the values expected for defect-free tubes. This performance ismore » made possible by omitting chemical treatments from the sample preparation process, thus avoiding the formation of defects. High-resolution imaging was used to directly determine the number of fractured shells and the chirality of the outer shell. Electron irradiation at 200 keV for 10, 100 and 1,800 s led to improvements in the maximum sustainable loads by factors of 2.4, 7.9 and 11.6 compared with non-irradiated samples of similar diameter. This effect is attributed to crosslinking between the shells. Computer simulations also illustrate the effects of various irradiation-induced crosslinking defects on load sharing between the shells.« less

  15. Multiwalled carbon nanotube monoliths prepared by spark plasma sintering (SPS) and their mechanical properties.

    PubMed

    Uo, Motohiro; Hasegawa, Tomoka; Akasaka, Tsukasa; Tanaka, Isao; Munekane, Fuminori; Omori, Mamoru; Kimura, Hisamichi; Nakatomi, Reiko; Soga, Kohei; Kogo, Yasuo; Watari, Fumio

    2009-01-01

    Three types of multiwalled carbon nanotube (MWCNT) monoliths without any binders were obtained by spark plasma sintering (SPS) treatment at 2000 degrees C under 80 MPa sintering pressure. Three MWCNTs with different diameters: thin (slashed circle20-30 nm, CNT Co., Ltd., Korea), thick (slashed circle100 nm, Nano Carbon Technologies Co., Ltd., Japan) and spherical thin (slashed circle20-30 nm, granulated diameter = 1-3 microm, Shimizu Corporation, Japan) were employed for SPS. SEM observation confirmed that these materials maintained the nanosized tube microstructure of raw CNT powder after SPS treatment. The densest monolith was prepared with the spherical MWCNTs. The mechanical properties of this material were estimated by the dynamic hardness test. The elastic modulus of the monolith did not depend on the difference of MWCNTs, but the hardness of spherical MWCNTs was higher than that of thick MWCNTs. The high density and hardness of the spherical MWCNTs were caused by the high packing density during the SPS process because of its spherical granulation. Thus, the spherical MWCNTs were most useful for the MWCNT monolith preparation with the SPS process and its application as a bone substitute material and a bone tissue engineering scaffold material was suggested.

  16. A highly sensitive hydrogen peroxide amperometric sensor based on MnO2-modified vertically aligned multiwalled carbon nanotubes.

    PubMed

    Xu, Bin; Ye, Min-Ling; Yu, Yu-Xiang; Zhang, Wei-De

    2010-07-26

    In this report, a highly sensitive amperometric sensor based on MnO(2)-modified vertically aligned multiwalled carbon nanotubes (MnO(2)/VACNTs) for determination of hydrogen peroxide (H(2)O(2)) was fabricated by electrodeposition. The morphology of the nanocomposite was characterized by scanning electron microscopy, energy-dispersive X-ray spectrometer and X-ray diffraction. Cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy were applied to investigate the electrochemical properties of the MnO(2)/VACNTs nanocomposite electrode. The mechanism for the electrochemical reaction of H(2)O(2) at the MnO(2)/VACNTs nanocomposite electrode was also discussed. In borate buffer (pH 7.8, 0.20 M), the MnO(2)/VACNTs nanocomposite electrode exhibits a linear dependence (R=0.998) on the concentration of H(2)O(2) from 1.2 x 10(-6)M to 1.8 x 10(-3)M, a high sensitivity of 1.08 x 10(6) microA M(-1) cm(-2) and a detection limit of 8.0 x 10(-7) M (signal/noise=3). Meanwhile, the MnO(2)/VACNTs nanocomposite electrode is also highly resistant towards typical inorganic salts and some biomolecules such as acetic acid, citric acid, uric acid and D-(+)-glucose, etc. In addition, the sensor based on the MnO(2)/VACNTs nanocomposite electrode was applied for the determination of trace of H(2)O(2) in milk with high accuracy, demonstrating its potential for practical application. Copyright 2010 Elsevier B.V. All rights reserved.

  17. A novel flexible nanogenerator made of ZnO nanoparticles and multiwall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Sun, Hui; Tian, He; Yang, Yi; Xie, Dan; Zhang, Yu-Chi; Liu, Xuan; Ma, Shuo; Zhao, Hai-Ming; Ren, Tian-Ling

    2013-06-01

    In this paper, a novel flexible nanogenerator (FNG) made of zinc-oxide (ZnO) nanoparticles (NPs) and multiwall-carbon nanotubes (MW-CNTs) is presented. In this structure, ZnO NPs and MW-CNTs are mixed with polydimethylsiloxane (PDMS) uniformly to form an entire flexible nanogenerator. Serial tests illustrate that the output voltage and power density are as high as 7.5 V and 18.75 μW per cycle, respectively. Furthermore, by foot stamp on the FNG, a peak voltage as high as 30 V can be generated. Comparing to the control samples, it is also proved that adding MW-CNTs into the matrix could significantly enhance the output voltage from 0.8 to 7.5 V. In summary, our work indicates that the realization of flexible nanogenerators made of ZnO NPs and MW-CNTs is technologically feasible, which may bring out some important and interesting applications in energy harvesting.In this paper, a novel flexible nanogenerator (FNG) made of zinc-oxide (ZnO) nanoparticles (NPs) and multiwall-carbon nanotubes (MW-CNTs) is presented. In this structure, ZnO NPs and MW-CNTs are mixed with polydimethylsiloxane (PDMS) uniformly to form an entire flexible nanogenerator. Serial tests illustrate that the output voltage and power density are as high as 7.5 V and 18.75 μW per cycle, respectively. Furthermore, by foot stamp on the FNG, a peak voltage as high as 30 V can be generated. Comparing to the control samples, it is also proved that adding MW-CNTs into the matrix could significantly enhance the output voltage from 0.8 to 7.5 V. In summary, our work indicates that the realization of flexible nanogenerators made of ZnO NPs and MW-CNTs is technologically feasible, which may bring out some important and interesting applications in energy harvesting. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00866e

  18. Comparison between Single-Walled CNT, Multi-Walled CNT, and Carbon Nanotube-Fiber Pyrograf III

    NASA Astrophysics Data System (ADS)

    Mousa, Marwan S.

    2018-02-01

    Single-Walled CNT (SWCNTs), Multi-walled Carbon Nanotubes (MWCNTs), and Carbon Nanotube-Fibers Pyrograf III PR-1 (CNTFs) were deposited by chemical vapor deposition under vacuum pressure value of (10-7mbar). Their structures were investigated by field emission microscopy. Carbon Nano-Fibers Pyrograf III PR-1 showed an average fiber diameter within the range of 100-200 nm and a length of (30-100) μm. Single-walled Carbon Nanotubes were produced by high-pressure Carbon Monoxide process with an average diameter ranging between (1-4) nm and a length of (1-3) μm. Thin Multiwall Carbon Nanotube of carbon purity (90%) showed an average diameter tube (9.5 nm) with a high-aspect-ratio (>150). The research work reported here includes the field electron emission current-voltage (I-V) characteristics and presented as Fowler-Nordheim (FN) plots and the spatial emission current distributions (electron emission images) obtained and analyzed in terms of electron source features. For the three types of emitters, a single spot pattern for the electron spatial; distributions were observed, with emission current fluctuations in some voltage region.

  19. Influence of multi-walled carbon nanotubes on the cognitive abilities of Wistar rats

    PubMed Central

    Sayapina, Nina V.; Sergievich, Alexander A.; Kuznetsov, Vladimir L.; Chaika, Vladimir V.; Lisitskaya, Irina G.; Khoroshikh, Pavel P.; Batalova, Tatyana A.; Tsarouhas, Kostas; Spandidos, Demetrios; Tsatsakis, Aristidis M.; Fenga, Concettina; Golokhvast, Kirill S.

    2016-01-01

    Studies of the neurobehavioral effects of carbon nanomaterials, particularly those of multi-walled carbon nanotubes (MWCNTs), have concentrated on cognitive effects, but data are scarce. The aim of this study was to assess the influence of MWCNTs on a number of higher nervous system functions of Wistar rats. For a period of 10 days, two experimental groups were fed with MWCNTs of different diameters (MWCNT-1 group, 8–10 nm; MWCNT-2 group, 18–20 nm) once a day at a dosage of 500 mg/kg. In the open-field test, reductions of integral indications of researching activity were observed for the two MWCNT-treated groups, with a parallel significant (P<0.01) increase in stress levels for these groups compared with the untreated control group. In the elevated plus-maze test, integral indices of researching activity in the MWCNT-1 and MWCNT-2 groups reduced by day 10 by 51 and 62%, respectively, while rat stress levels remained relatively unchanged. In the universal problem solving box test, reductions in motivation and energy indices of researching activity were observed in the two experimental groups. Searching activity in the MWCNT-1 group by day 3 was reduced by 50% (P<0.01) and in the MWCNT-2 group the relevant reduction reached 11.2%. By day 10, the reduction compared with controls, was 64% (P<0.01) and 58% (P<0.01) for the MWCNT-1 and MWCNT-2 groups, respectively. In conclusion, a series of specific tests demonstrated that MWCNT-treated rats experienced a significant reduction of some of their cognitive abilities, a disturbing and worrying finding, taking into consideration the continuing and accelerating use of carbon nanotubes in medicine and science. PMID:27588053

  20. Pseudocapacitive Desalination of Brackish Water and Seawater with Vanadium-Pentoxide-Decorated Multiwalled Carbon Nanotubes.

    PubMed

    Lee, Juhan; Srimuk, Pattarachai; Aristizabal, Katherine; Kim, Choonsoo; Choudhury, Soumyadip; Nah, Yoon-Chae; Mücklich, Frank; Presser, Volker

    2017-09-22

    A hybrid membrane pseudocapacitive deionization (MPDI) system consisting of a hydrated vanadium pentoxide (hV 2 O 5 )-decorated multi-walled carbon nanotube (MWCNT) electrode and one activated carbon electrode enables sodium ions to be removed by pseudocapacitive intercalation with the MWCNT-hV 2 O 5 electrode and chloride ion to be removed by non-faradaic electrosorption of the porous carbon electrode. The MWCNT-hV 2 O 5 electrode was synthesized by electrochemical deposition of hydrated vanadium pentoxide on the MWCNT paper. The stable electrochemical operating window for the MWCNT-hV 2 O 5 electrode was between -0.5 V and +0.4 V versus Ag/AgCl, which provided a specific capacity of 44 mAh g -1 (corresponding with 244 F g -1 ) in aqueous 1 m NaCl. The desalination performance of the MPDI system was investigated in aqueous 200 mm NaCl (brackish water) and 600 mm NaCl (seawater) solutions. With the aid of an anion and a cation exchange membrane, the MPDI hybrid cell was operated from -0.4 to +0.8 V cell voltage without crossing the reduction and oxidation potential limit of both electrodes. For the 600 mm NaCl solution, the NaCl salt adsorption capacity of the cell was 23.6±2.2 mg g -1 , which is equivalent to 35.7±3.3 mg g -1 normalized to the mass of the MWCNT-hV 2 O 5 electrode. Additionally, we propose a normalization method for the electrode material with faradaic reactions based on sodium uptake capacities. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Enhancement of electrical conductivity by changing phase morphology for composites consisting of polylactide and poly(ε-caprolactone) filled with acid-oxidized multiwalled carbon nanotubes.

    PubMed

    Xu, Zhaohua; Zhang, Yaqiong; Wang, Zhigang; Sun, Ning; Li, Heng

    2011-12-01

    Composites consisting of polylactide (PLA) and poly(ε-caprolactone) (PCL) filled with acid-oxidized multiwalled carbon nanotubes (A-MWCNTs) were prepared through melt compounding. Phase morphologies of PLA/PCL/A-MWCNT composites with different contents of filled A-MWCNTs and PCL compositions were mainly observed by scanning electron microscope. The results show that A-MWCNTs are selectively dispersed in the PCL phase, regardingless of PCL phase domain sizes. For PLA/PCL/A-MWCNT composites with fixed PLA/PCL ratio of 95/5, the dispersed PCL phase domain sizes in the PLA matrix decrease even though a small content of A-MWCNTs is added, compared with PLA/PCL blend with the same composition, indicating that A-MWCNTs effectively prevent from coalescence of the dispersed PCL phase domains. With filling of 1.0 wt % A-MWCNTs, an interesting change of electrical conductivity for PLA/PCL/A-MWCNT composites is observed, in which the maximum conductivity is observed for PLA/PCL/A-MWCNT composite with PLA/PCL ratio of 60/40. The result is well-explained by the formed cocontinuous phase morphology and effective A-MWCNT content. © 2011 American Chemical Society

  2. Construction of an electrochemical sensor based on the electrodeposition of Au-Pt nanoparticles mixtures on multi-walled carbon nanotubes film for voltammetric determination of cefotaxime.

    PubMed

    Shahrokhian, Saeed; Rastgar, Shokoufeh

    2012-06-07

    Mixtures of gold-platinum nanoparticles (Au-PtNPs) are fabricated consecutively on a multi-walled carbon nanotubes (MWNT) coated glassy carbon electrode (GCE) by the electrodeposition method. The surface morphology and nature of the hybrid film (Au-PtNPs/MWCNT) deposited on glassy carbon electrodes is characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The modified electrode is used as a new and sensitive electrochemical sensor for the voltammetric determination of cefotaxime (CFX). The electrochemical behavior of CFX is investigated on the surface of the modified electrode using linear sweep voltammetry (LSV). The results of voltammetric studies exhibited a considerable improvement in the oxidation peak current of CFX compared to glassy carbon electrodes individually coated with MWCNT or Au-PtNPs. Under the optimized conditions, the modified electrode showed a wide linear dynamic range of 0.004-10.0 μM with a detection limit of 1.0 nM for the voltammetric determination of CFX. The modified electrode was successfully applied for the accurate determination of trace amounts of CFX in pharmaceutical and clinical preparations.

  3. A New Sensitive Sensor for Simultaneous Differential Pulse Voltammetric Determination of Codeine and Acetaminophen Using a Hydroquinone Derivative and Multiwall Carbon Nanotubes Carbon Paste Electrode

    PubMed Central

    Garazhian, Elahe; Shishehbore, M. Reza

    2015-01-01

    A new sensitive sensor was fabricated for simultaneous determination of codeine and acetaminophen based on 4-hydroxy-2-(triphenylphosphonio)phenolate (HTP) and multiwall carbon nanotubes paste electrode at trace levels. The sensitivity of codeine determination was deeply affected by spiking multiwall carbon nanotubes and a modifier in carbon paste. Electron transfer coefficient, α, catalytic electron rate constant, k, and the exchange current density, j 0, for oxidation of codeine at the HTP-MWCNT-CPE were calculated using cyclic voltammetry. The calibration curve was linear over the range 0.2–844.7 μM with two linear segments, and the detection limit of 0.063 μM of codeine was obtained using differential pulse voltammetry. The modified electrode was separated codeine and acetaminophen signals by differential pulse voltammetry. The modified electrode was applied for the determination of codeine and acetaminophen in biological and pharmaceutical samples with satisfactory results. PMID:25945094

  4. Synthesis and Catalytic Applications of Multi-Walled Carbon Nanotube-Polyamidoamine Dendrimer Hybrids.

    PubMed

    Desmecht, Antonin; Steenhaut, Timothy; Pennetreau, Florence; Hermans, Sophie; Riant, Olivier

    2018-06-20

    Polyamidoamine (PAMAM) dendrimers were covalently immobilized on multi-walled carbon nanotubes (MWNT) via two 'grafting to' strategies. We demonstrate the existence of non-covalent interactions between the two components but outline the superiority of our two grafting approaches, namely xanthate and click chemistry. MWNT surfaces were functionalized with activated ester and propargylic moieties prior to their reaction with PAMAM or azido-PAMAM dendrimers, respectively. The grafting of PAMAM generations 0 to 3 was evaluated with X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The versatility of our hybrids was demonstrated by post-functionalization sequences involving copper alkyne-azide cycloaddition (CuAAC). We synthesized homogeneous supported iridium complexes at the extremities of the dendrimers. In addition, our materials were used as template for the encapsulation of Pd nanoparticles (NP), validating our nanocomposites for catalytic applications. The palladium-based catalyst was active for carbonylative coupling during 5 consecutive runs without loss of activity. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Efficient removal of cadmium using magnetic multiwalled carbon nanotube nanoadsorbents: equilibrium, kinetic, and thermodynamic study

    NASA Astrophysics Data System (ADS)

    Pashai Gatabi, Maliheh; Milani Moghaddam, Hossain; Ghorbani, Mohsen

    2016-07-01

    Adsorptive potential of maghemite decorated multiwalled carbon nanotubes (MWCNTs) for the removal of cadmium ions from aqueous solution was investigated. The magnetic nanoadsorbent was synthesized using a versatile and cost effective chemical route. Structural, magnetic and surface charge properties of the adsorbent were characterized using FTIR, XRD, TEM, VSM analysis and pHPZC determination. Batch adsorption experiments were performed under varied system parameters such as pH, contact time, initial cadmium concentration and temperature. Highest cadmium adsorption was obtained at pH 8.0 and contact time of 30 min. Adsorption behavior was kinetically studied using pseudo first-order, pseudo second-order, and Weber-Morris intra particle diffusion models among which data were mostly correlated to pseudo second-order model. Adsorbate-adsorbent interactions as a function of temperature was assessed by Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin isotherm models from which Freundlich model had the highest consistency with the data. The adsorption capacity increased with increasing temperature and maximum Langmuir's adsorption capacity was found to be 78.81 mg g-1 at 298 K. Thermodynamic parameters and activation energy value suggest that the process of cadmium removal was spontaneous and physical in nature, which lead to fast kinetics and high regeneration capability of the nanoadsorbent. Results of this work are of great significance for environmental applications of magnetic MWCNTs as promising adsorbent for heavy metals removal from aqueous solutions.

  6. Multi-walled carbon nanotubes suppress potassium channel activities in PC12 cells

    NASA Astrophysics Data System (ADS)

    Xu, Haifei; Bai, Juan; Meng, Jie; Hao, Wei; Xu, Haiyan; Cao, Ji-Min

    2009-07-01

    The advancement in nanotechnology has produced technological and conceptual breakthroughs but the effects nanomaterials have on organisms at the cellular level are poorly understood. Here we report that carboxyl-terminated multi-walled carbon nanotubes (MWCNTs) act as antagonists of three types of potassium channels as assessed by whole-cell patch clamp electrophysiology on undifferentiated pheochromocytoma (PC12) cells. Our results showed that carboxyl-terminated MWCNTs suppress the current densities of Ito, IK and IK1 in a time-dependent and irreversible manner. The suppressions were most distinct 24 h after incubation with MWCNTs. However, MWCNTs did not significantly change the expression levels of reactive oxygen species (ROS) or intracellular free calcium and also did not alter the mitochondrial membrane potential (ΔΨm) in PC12 cells. These results suggest that oxidative stress was not involved in the MWCNTs suppression of Ito, IK and IK1 current densities. Nonetheless, the suppression of potassium currents by MWCNTs will impact on electrical signaling of excitable cells such as neurons and muscles.

  7. Super-hydrophobic multi-walled carbon nanotube coatings for stainless steel.

    PubMed

    De Nicola, Francesco; Castrucci, Paola; Scarselli, Manuela; Nanni, Francesca; Cacciotti, Ilaria; De Crescenzi, Maurizio

    2015-04-10

    We have taken advantage of the native surface roughness and the iron content of AISI 316 stainless steel to directly grow multi-walled carbon nanotube (MWCNT) random networks by chemical vapor deposition (CVD) at low-temperature (1000°C) without the addition of any external catalysts or time-consuming pre-treatments. In this way, super-hydrophobic MWCNT films on stainless steel sheets were obtained, exhibiting high contact angle values (154°C) and high adhesion force (high contact angle hysteresis). Furthermore, the investigation of MWCNT films with scanning electron microscopy (SEM) reveals a two-fold hierarchical morphology of the MWCNT random networks made of hydrophilic carbonaceous nanostructures on the tip of hydrophobic MWCNTs. Owing to the Salvinia effect, the hydrophobic and hydrophilic composite surface of the MWCNT films supplies a stationary super-hydrophobic coating for conductive stainless steel. This biomimetical inspired surface not only may prevent corrosion and fouling, but also could provide low friction and drag reduction.

  8. Removal of inorganic mercury from aquatic environments by multi-walled carbon nanotubes.

    PubMed

    Yaghmaeian, Kamyar; Khosravi Mashizi, Reza; Nasseri, Simin; Mahvi, Amir Hossein; Alimohammadi, Mahmood; Nazmara, Shahrokh

    2015-01-01

    Mercury is considered as a toxic heavy metal in aquatic environments due to accumulation in bodies of living organisms. Exposure to mercury may lead to different toxic effects in humans including damages to kidneys and nervous system. Multi-walled carbon nanotubes (MWCNTs) were selected as sorbent to remove mercury from aqueous solution using batch technique. ICP instrument was used to determine the amount of mercury in solution. Moreover, pH, contact time and initial concentration of mercury were studied to determine the influence of these parameters on the adsorption conditions. Results indicate that the adsorption strongly depended on pH and the best pH for adsorption is about 7. The rate of adsorption process initially was rapid but it was gradually reduced with increasing of contact time and reached the equilibrium after 120 min. In addition, more than 85 % of initial concentration of 0.1 mg/l was removed at 0.5 g/l concentration of sorbent and contact time of 120 min. Meanwhile, the adsorption process followed the pseudo second-order model and the adsorption isotherms could be described by both the Freundlich and the Langmuir models. This study showed that MWCNTs can effectively remove inorganic mercury from aqueous solutions as adsorbent.

  9. Hyaluronate tethered, "smart" multiwalled carbon nanotubes for tumor-targeted delivery of doxorubicin.

    PubMed

    Datir, Satyajit R; Das, Manasmita; Singh, Raman Preet; Jain, Sanyog

    2012-11-21

    The present study reports the optimized synthesis, physicochemical characterization, and biological evaluation of a novel, multiwalled carbon nanotube-hyaluronic acid (MWCNT-HA) conjugate, complexed with an anticancer agent, Doxorubicin (DOX) via π-π stacking interaction. The therapeutic conjugate was concomitantly labeled with a near-infrared fluorescent dye, Alexa-Flour-647 (AF-647), and radiotracer Technetium-99m ((99m)Tc) to track its whereabouts both in vitro and in vivo via optical and scintigraphic imaging techniques. Covalent functionalization of MWCNTs with HA facilitated their internalization into human lung adenocarcinoma, A549 cells via hyaluronan receptors (HR) mediated endocytosis. Internalized nanotubes showed lysosomal trafficking, followed by low pH-triggered DOX release under endolysosomal conditions. Consequently, DOX-loaded HA-MWCNTs exhibited 3.2 times higher cytotoxicity and increased apoptotic activity than free DOX in equivalent concentrations. Organ distribution studies in Ehlrich ascites tumor (EAT) bearing mice model indicated that tumor specific localization of (99m)Tc-MWCNT-HA-DOX is significantly higher than both free drug and nontargeted MWCNTs. Pharmacodynamic studies in chemically breast-cancer-induced rats showed that the tumor-growth inhibitory effect of HA-MWCNT-DOX was 5 times higher than free DOX in equivalent concentration. DOX delivered through HA-MWCNTs was devoid of any detectable cardiotoxity, hepatotoxicity, or nephrotoxicity. All these promising attributes make HA-MWCNTs a "smart" platform for tumor-targeted delivery of anticancer agents.

  10. Selective uptake of multi-walled carbon nanotubes by tumor macrophages in a murine glioma model.

    PubMed

    VanHandel, Michelle; Alizadeh, Darya; Zhang, Leying; Kateb, Babak; Bronikowski, Michael; Manohara, Harish; Badie, Behnam

    2009-03-31

    Carbon nantotubes (CNTs) are emerging as a new family of nanovectors for drug and gene delivery into biological systems. To evaluate potential application of this technology for brain tumor therapy, we studied uptake and toxicity of multi-walled CNTs (MWCNTs) in the GL261 murine intracranial glioma model. Within 24 h of a single intratumoral injection of labeled MWCNTs (5 microg), nearly 10-20% of total cells demonstrated CNT internalization. Most CNT uptake, however, occurred by tumor-associated macrophages (MP), which accounted for most (75%) MWCNT-positive cells. Within 24 h of injection, nearly 30% of tumor MP became MWCNT-positive. Despite a transient increase in inflammatory cell infiltration into both normal and tumor-bearing brains following MWCNT injection, no significant toxicity was noted in mice, and minor changes in tumor cytokine expression were observed. This study suggests that MWCNTs could potentially be used as a novel and non-toxic vehicle for targeting MP in brain tumors.

  11. Biosynthesis of Bacterial Cellulose/Carboxylic Multi-Walled Carbon Nanotubes for Enzymatic Biofuel Cell Application

    PubMed Central

    Lv, Pengfei; Feng, Quan; Wang, Qingqing; Li, Guohui; Li, Dawei; Wei, Qufu

    2016-01-01

    Novel nanocomposites comprised of bacterial cellulose (BC) with carboxylic multi-walled carbon nanotubes (c-MWCNTs) incorporated into the BC matrix were prepared through a simple method of biosynthesis. The biocathode and bioanode for the enzyme biological fuel cell (EBFC) were prepared using BC/c-MWCNTs composite injected by laccase (Lac) and glucose oxidase (GOD) with the aid of glutaraldehyde (GA) crosslinking. Biosynthesis of BC/c-MWCNTs composite was characterized by digital photos, scanning electron microscope (SEM), and Fourier Transform Infrared (FTIR). The experimental results indicated the successful incorporation of c-MWCNTs into the BC. The electrochemical and biofuel performance were evaluated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The power density and current density of EBFCs were recorded at 32.98 µW/cm3 and 0.29 mA/cm3, respectively. Additionally, the EBFCs also showed acceptable stability. Preliminary tests on double cells indicated that renewable BC have great potential in the application field of EBFCs. PMID:28773310

  12. The detection of formaldehyde using microelectromechanical acoustic resonator with multiwalled carbon nanotubes-polyethyleneimine composite coating

    NASA Astrophysics Data System (ADS)

    Wang, Jingjing; Zhan, Da; Wang, Ke; Hang, Weiwei

    2018-01-01

    A micro-scale gas sensor based on mass-sensitive film bulk acoustic resonator is demonstrated for the detection of trace formaldehyde at room temperature. The composites mixed with multiwalled carbon nanotubes and polyethyleneimine (MWNTs-PEI) were coated on the resonator surface as the sensitive layer to specifically absorb formaldehyde molecules using a facile spray process. The influence of spraying processes on the formaldehyde sensing properties were investigated. Different response behaviors were determined by both the chemical absorption between formaldehyde molecules and the amine functional groups on PEI and the increase of absorption surface came from the nanostructure. The combination of high frequency of the film bulk acoustic resonator (~4.3 GHz) and the specific absorbability of MWNTs-PEI composites provided a high sensitivity in the detections of trace formaldehyde. The obtained ultra-low limit of detection was as low as 60 ppb with linear response, quick response/recovery time, good reproducibility and selectivity. The proposed sensor shows potential as a portable and convenient gas-sensing system for monitoring the low-level concentration of indoor air pollution.

  13. Real time radiation dosimeters based on vertically aligned multiwall carbon nanotubes and graphene.

    PubMed

    Funaro, Maria; Sarno, Maria; Ciambelli, Paolo; Altavilla, Claudia; Proto, Antonio

    2013-02-22

    Measurements of the absorbed dose and quality assurance programs play an important role in radiotherapy. Ionization chambers (CIs) are considered the most important dosimeters for their high accuracy, practicality and reliability, allowing absolute dose measurements. However, they have a relative large physical size, which limits their spatial resolution, and require a high bias voltage to achieve an acceptable collection of charges, excluding their use for in vivo dosimetry. In this paper, we propose new real time radiation detectors with electrodes based on graphene or vertically aligned multiwall carbon nanotubes (MWCNTs). We have investigated their charge collection efficiency and compared their performance with electrodes made of a conventional material. Moreover, in order to highlight the effect of nanocarbons, reference radiation detectors were also tested. The proposed dosimeters display an excellent linear response to dose and collect more charge than reference ones at a standard bias voltage, permitting the construction of miniaturized CIs. Moreover, an MWCNT based CI gives the best charge collection efficiency and it enables working also to lower bias voltages and zero volts, allowing in vivo applications. Graphene based CIs show better performance with respect to reference dosimeters at a standard bias voltage. However, at decreasing bias voltage the charge collection efficiency becomes worse if compared to a reference detector, likely due to graphene's semiconducting behavior.

  14. Fabrication of free-standing aligned multiwalled carbon nanotube array for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Bulusheva, L. G.; Arkhipov, V. E.; Fedorovskaya, E. O.; Zhang, Su; Kurenya, A. G.; Kanygin, M. A.; Asanov, I. P.; Tsygankova, A. R.; Chen, Xiaohong; Song, Huaihe; Okotrub, A. V.

    2016-04-01

    We show that a high-temperature CCl4 vapor treatment of vertically aligned multiwalled carbon nanotubes (VA-MWCNTs) grown on silicon substrate allows carefully detach the array from the substrate. Moreover, this procedure partially purifies the VA-MWCNTs from the residual iron catalyst. To improve electrical connectivity of free-standing VA-MWCNTs in an electrochemical cell, the array was placed between the layers of Ni foam. Such assembly demonstrated the better performance in Li-battery as compared to the disordered MWCNTs. After 50 cycles, the specific capacity of VA-MWCNT array synthesized from 0.5 wt% ferrocene solution in toluene was 350 mAh g-1 at a current density of 0.1 A g-1, while the battery with the disordered MWCNTs achieved 197 mAh g-1 only. By the results of electrochemical impedance spectroscopy, the higher capacity of VA-MWCNTs was attributed to larger surface area available for electrolyte and Li ions due to the absence of binder coating.

  15. Multi-Wall Carbon Nanotubes as Lithium Nanopipettes and SPM Probes

    NASA Astrophysics Data System (ADS)

    Larson, Jonathan; Bharath, Satyaveda; Cullen, William; Reutt-Robey, Janice

    2014-03-01

    A multi-walled carbon nanotube (MWCNT) - terminated SPM cantilever, was utilized to perform nanolithography and surface diffusion measurements on a thin film of vapor-deposited lithium atop a silicon (111) substrate under ultra-high vacuum conditions. In these investigations the MWCNT tip was shown to act as both a lithium nanopipette and a probe for non-contact atomic force microscopy (NC-AFM) measurements. With the application of appropriate bias conditions, the MWCNT could site-selectively extract (expel) nano-scale amounts of lithium from (to) the sample surface. Depressions, mounds, and spikes were generated on the surface in this way and were azimuthally symmetric about the selected point of pipetting. Following lithium transfer to/from the substrate, the MWCNT pipette-induced features were sequentially imaged with NC-AFM using the MWCNT as the probe. Vacancy pits of ca. 300 nm diameter and 1.5 nm depth were observed to decay on a timescale of hours at room temperature, through diffusion-limited decay processes. A continuum model was utilized to simulate the island decay rates, and the lithium surface diffusion coefficient of D =7.5 (+/-1.3)*10-15 cm2/s was extracted. U.S. Department of Energy Award Number DESC0001160.

  16. Ubiquitous Low-Cost Functionalized Multi-Walled Carbon Nanotube Sensors for Distributed Methane Leak Detection

    DOE PAGES

    Humayun, Md Tanim; Divan, Ralu; Stan, Liliana; ...

    2016-06-16

    This paper presents a highly sensitive, energy efficient and low-cost distributed methane (CH 4) sensor system (DMSS) for continuous monitoring, detection, and localization of CH 4 leaks in natural gas infrastructure, such as transmission and distribution pipelines, wells, and production pads. The CH 4 sensing element, a key component of the DMSS, consists of a metal oxide nanocrystal (MONC) functionalized multi-walled carbon nanotube (MWCNT) mesh which, in comparison to existing literature, shows stronger relative resistance change while interacting with lower parts per million (ppm) concentration of CH 4. A Gaussian plume triangulation algorithm has been developed for the DMSS. Givenmore » a geometric model of the surrounding environment the algorithm can precisely detect and localize a CH 4 leak as well as estimate its mass emission rate. A UV-based surface recovery technique making the sensor recover 10 times faster than the reported ones is presented for the DMSS. In conclusion, a control algorithm based on the UV-accelerated recovery is developed which facilitates faster leak detection.« less

  17. Synthesis and properties of platinum on multiwall carbon nanotube modified by chitosan

    NASA Astrophysics Data System (ADS)

    Fikriyyah, A. K.; Chaldun, E. R.; Indriyati

    2018-03-01

    Platinum nanoparticles on multiwall carbon nanotubes (Pt/MWCNT) play an important role in fuel cell to convert the chemical energy from a fuel into electricity. In this study, Pt/MWCNT electrocatalysts were prepared by chemical reduction of the metal salts in chitosan as the support. Firstly, commercial MWCNTs were functionalized by oxidative process using a mixture of nitric acid and sulfuric acid. Then, functionalized MWCNTs were mixed with chitosan-acetic acid solution to conduct grafting reaction with NH2 groups in chitosan by solution polymerization method. Platinum nanoparticles were loaded onto the surface of the MWCNTs after hexachloroplatinic acid was reduced by sodium hydroxide solution. The result showed that Pt was attached on MWCNT based on analysis from EDS, XRD, and UV Vis Spectroscopy. UV Vis analysis indicates the plasmon absorbance band of Pt nanoparticles in Pt/MWCNT, while XRD analysis confirmed the size of Pt particle in nanometer. This elucidates the potential procedure to synthesize Pt/MWCNT using chitosan.

  18. Toxicity of multi-walled carbon nanotubes, graphene oxide, and reduced graphene oxide to zebrafish embryos.

    PubMed

    Liu, Xiao Tong; Mu, Xi Yan; Wu, Xiao Li; Meng, Li Xuan; Guan, Wen Bi; Ma, Yong Qiang; Sun, Hua; Wang, Cheng Ju; Li, Xue Feng

    2014-09-01

    This study was aimed to investigate the toxic effects of 3 nanomaterials, i.e. multi-walled carbon nanotubes (MWCNTs), graphene oxide (GO), and reduced graphene oxide (RGO), on zebrafish embryos. The 2-h post-fertilization (hpf) zebrafish embryos were exposed to MWCNTs, GO, and RGO at different concentrations (1, 5, 10, 50, 100 mg/L) for 96 h. Afterwards, the effects of the 3 nanomateria on spontaneous movement, heart rate, hatching rate, length of larvae, mortality, and malformations ls were evaluated. Statistical analysis indicated that RGO significantly inhibited the hatching of zebrafish embryos. Furthermore, RGO and MWCNTs decreased the length of the hatched larvae at 96 hpf. No obvious morphological malformation or mortality was observed in the zebrafish embryos after exposure to the three nanomaterials. MWCNTs, GO, and RGO were all toxic to zebrafish embryos to influence embryos hatching and larvae length. Although no obvious morphological malformation and mortality were observed in exposed zebrafish embryos, further studies on the toxicity of the three nanomaterials are still needed. Copyright © 2014 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

  19. Design of Amorphous Manganese Oxide@Multiwalled Carbon Nanotube Fiber for Robust Solid-State Supercapacitor.

    PubMed

    Shi, Peipei; Li, Li; Hua, Li; Qian, Qianqian; Wang, Pengfei; Zhou, Jinyuan; Sun, Gengzhi; Huang, Wei

    2017-01-24

    Solid-state fiber-based supercapacitors have been considered promising energy storage devices for wearable electronics due to their lightweight and amenability to be woven into textiles. Efforts have been made to fabricate a high performance fiber electrode by depositing pseudocapacitive materials on the outer surface of carbonaceous fiber, for example, crystalline manganese oxide/multiwalled carbon nanotubes (MnO 2 /MWCNTs). However, a key challenge remaining is to achieve high specific capacitance and energy density without compromising the high rate capability and cycling stability. In addition, amorphous MnO 2 is actually preferred due to its disordered structure and has been proven to exhibit superior electrochemical performance over the crystalline one. Herein, by incorporating amorphous MnO 2 onto a well-aligned MWCNT sheet followed by twisting, we design an amorphous MnO 2 @MWCNT fiber, in which amorphous MnO 2 nanoparticles are distributed in MWCNT fiber uniformly. The proposed structure gives the amorphous MnO 2 @MWCNT fiber good mechanical reliability, high electrical conductivity, and fast ion-diffusion. Solid-state supercapacitor based on amorphous MnO 2 @MWCNT fibers exhibits improved energy density, superior rate capability, exceptional cycling stability, and excellent flexibility. This study provides a strategy to design a high performance fiber electrode with microstructure control for wearable energy storage devices.

  20. The impact of multi-walled carbon nanotubes (MWCNTs) on macrophages: contribution of MWCNT characteristics.

    PubMed

    Li, Yinghe; Cao, Jimin

    2018-05-22

    Multi-walled carbon nanotubes (MWCNTs) have wide application prospects but also exhibit notable biotoxicity that is tightly associated with macrophages. Macrophages simultaneously act as initiators and defenders in MWCNT-induced organ lesions, and targeting macrophages with MWCNTs may be a potential immunotherapy and oncotherapy approach. This review focuses on the impacts of MWCNTs on macrophages and further discusses the influence of MWCNT characteristics on their bioactivity. Based on existing studies, MWCNTs stimulate macrophage migration, induce secretion of various cytokines and activate inflammatory pathways in macrophages, especially NLRP3-mediated IL-1β production. This inflammatory state, together with the oxidative stress and cell membrane lesions induced by MWCNTs, contributes to decreased phagocytic ability and cell viability, which finally results in cell apoptosis and necrosis. A series of intracellular and systemic components, such as toll-like receptor, high-mobility group box 1, Rho-associated kinases, scavenger receptor and complement components, may be involved in the above-mentioned cell-MWCNT interactions. The characteristics of MWCNTs can influence their bioactivity in macrophages both mechanically and chemically. The size (length and/or diameter), functionalization, purification and even the experimental method can affect the influence of MWCNTs on macrophages, and a better understanding of these MWCNT characteristics may benefit utilization of this nanomaterial in associated nanomedical applications.

  1. Structural, thermal and electrical characterizations of multiwalled carbon nanotubes and polyaniline composite

    SciTech Connect

    Singh, Kamal, E-mail: singhkamal204@gmail.com; Garg, Leena; Singh, Jaspal

    2016-05-06

    The undoped and doped composite of MWNTs (Multiwalled Carbon Nanotubes) with PANI (/Polyaniline) was prepared by chemical oxidative polymerization. The MWNTs/PANI composites have been characterized by using various techniques like Thermogravometric Analysis (TGA), Fourier transform infrared (FT-IR) spectrometer and Field emission scanning electron microscope (FE-SEM) and conductivity measurement by using two probe method. TGA results has shown that thermal stability followed the pattern undoped MWNTs/PANI composite < doped MWNTs/PANI composite. FE-SEM micrographs demonstrated the morphological changes on the surface of MWNTs as a result of composite formation. Fourier transformed infrared (FT-IR) spectra ascertained the formation of the composite. Study ofmore » electrical characteristics demonstrated that the doped MWNTs/PANI composite (1.2 × 10{sup 1} Scm{sup −1}) have better conductivity than the undoped MWNTs/PANI composite (10{sup −4} Scm{sup −1}). These CNTs based polymeric composites are of great importance in developing new nano-scale devices for future chemical, mechanical and electronic applications.« less

  2. A comparative study of enzyme immobilization strategies for multi-walled carbon nanotube glucose biosensors

    NASA Astrophysics Data System (ADS)

    Shi, Jin; Claussen, Jonathan C.; McLamore, Eric S.; Haque, Aeraj ul; Jaroch, David; Diggs, Alfred R.; Calvo-Marzal, Percy; Rickus, Jenna L.; Porterfield, D. Marshall

    2011-09-01

    This work addresses the comparison of different strategies for improving biosensor performance using nanomaterials. Glucose biosensors based on commonly applied enzyme immobilization approaches, including sol-gel encapsulation approaches and glutaraldehyde cross-linking strategies, were studied in the presence and absence of multi-walled carbon nanotubes (MWNTs). Although direct comparison of design parameters such as linear range and sensitivity is intuitive, this comparison alone is not an accurate indicator of biosensor efficacy, due to the wide range of electrodes and nanomaterials available for use in current biosensor designs. We proposed a comparative protocol which considers both the active area available for transduction following nanomaterial deposition and the sensitivity. Based on the protocol, when no nanomaterials were involved, TEOS/GOx biosensors exhibited the highest efficacy, followed by BSA/GA/GOx and TMOS/GOx biosensors. A novel biosensor containing carboxylated MWNTs modified with glucose oxidase and an overlying TMOS layer demonstrated optimum efficacy in terms of enhanced current density (18.3 ± 0.5 µA mM - 1 cm - 2), linear range (0.0037-12 mM), detection limit (3.7 µM), coefficient of variation (2%), response time (less than 8 s), and stability/selectivity/reproducibility. H2O2 response tests demonstrated that the most possible reason for the performance enhancement was an increased enzyme loading. This design is an excellent platform for versatile biosensing applications.

  3. Preparation and characterization of bagasse/HDPE composites using multi-walled carbon nanotubes.

    PubMed

    Ashori, Alireza; Sheshmani, Shabnam; Farhani, Foad

    2013-01-30

    This article presents the preparation and characterization of bagasse/high density polyethylene (HDPE) composites. The effects of multi-walled carbon nanotubes (MWCNTs), as reinforcing agent, on the mechanical and physical properties were also investigated. In order to increase the interphase adhesion, maleic anhydride grafted polyethylene (MAPE) was added as a coupling agent to all the composites studied. In the sample preparation, MWCNTs and MAPE contents were used as variable factors. The morphology of the specimens was characterized using scanning electron microscopy (SEM) technique. The results of strength measurement indicated that when 1.5 wt% MWCNTs were added, tensile and flexural properties reached their maximum values. At high level of MWCNTs loading (3 or 4 wt%), increased population of MWCNTs lead to agglomeration and stress transfer gets blocked. The addition of MWCNTs filler slightly decreased the impact strength of composites. Both mechanical and physical properties were improved when 4 wt% MAPE was applied. SEM micrographs also showed that the surface roughness improved with increasing MAPE loading from 0 to 4 wt%. The improvement of physicomechanical properties of composites confirmed that MWCNTs have good reinforcement and the optimum synergistic effect of MWCNTs and MAPE was achieved at the combination of 1.5 and 4 wt%, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Novel aminohydrazide cross-linked chitosan filled with multi-walled carbon nanotubes as antimicrobial agents.

    PubMed

    Mohamed, Nadia A; Abd El-Ghany, Nahed A

    2018-04-21

    Four chemically modified chitosan derivatives 1-4 were designed and synthesized via a series of four reactions; first by reaction with benzaldehyde to protect its amino groups (Derivative 1), second by reaction with epichlorohydrine (Derivative 2), third by reaction with aminobenzhydrazide (Derivative 3), and forth by removing of benzaldehyde to restore the free amino groups on the chitosan (Derivative 4). Two multi-walled carbon nanotube (MWCNT) biocomposites based on Derivative 4 were also prepared. The structure of the prepared derivatives and MWCNT composites was elucidated using elemental analyses, FTIR, XRD, SEM and TEM. The modified chitosan derivatives and MWCNT composites showed better antimicrobial activities than that of chitosan against Enterococcus faecalis, Staphylococcus epidermidis, Escherichia coli, Aspergillus niger, Cryptococcus neoformans and Candida tropicalis as judged by their higher inhibition zone diameters using the agar well diffusion technique. These derivatives and MWCNT composites are more potent against Gram-positive bacteria than against Gram-negative bacteria. The MWCNT composites displayed comparable or even better antimicrobial activities than the reference bactericides or fungicides. Thus, structural modification of chitosan through combination with functionalized moieties and MWCNTs in one system was taken as a way to achieve promising templates for antimicrobial agents and to be appropriate candidates for medical applications. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Multiwalled Carbon Nanotube/nanofiber Arrays as Conductive and Dry Adhesive Interface Materials

    NASA Technical Reports Server (NTRS)

    Tong, Tao; Zhao, Yang; Delzeit, Lance; Majumdar, Arun; Kashani, Ali

    2004-01-01

    We demonstrate the possibility of making conductive and dry adhesive interfaces between multiwalled carbon nanotube (MWNT) and nanofiber (MWNF) arrays grown by chemical vapor deposition with transition-metal as catalyst on highly Boron doped silicon substrates. The maximum observed adhesion force between MWNT and MWNF surfaces is 3.5 mN for an apparent contact area of 2 mm by 4 mm. The minimum contact resistance measured at the same time is approx.20 Omega. Contact resistances of MWNT-MWNT and MWNT-gold interfaces were also measured as pressure forces around several mN were applied at the interface. The resulting minimum contact resistances are on the same order but with considerable variation from sample to sample. For MWNT-MWNT contacts, a minimum contact resistance of approx.1 Omega is observed for a contact area of 2 mm by 1 mm. The relatively high contact resistances, considering the area density of the nanotubes, might be explained by the high cross-tube resistances at the contact interfaces.

  6. Oriented Polyaniline Nanowire Arrays Grown on Dendrimer (PAMAM) Functionalized Multiwalled Carbon Nanotubes as Supercapacitor Electrode Materials.

    PubMed

    Jin, Lin; Jiang, Yu; Zhang, Mengjie; Li, Honglong; Xiao, Linghan; Li, Ming; Ao, Yuhui

    2018-04-19

    At present, PANI/MWNT composites have been paid more attention as promising electrode materials in supercapacitors. Yet some shortcomings still limit the widely application of PANI/MWNT electrolytes. In this work, in order to improve capacitance ability and long-term stability of electrode, a multi-amino dendrimer (PAMAM) had been covalently linked onto multi-walled carbon nanotubes (MWNT) as a bridge to facilitating covalent graft of polyaniline (PANI), affording P-MWNT/PANI electrode composites for supercapacitor. Surprisingly, ordered arrays of PANI nanowires on MWNT (setaria-like morphology) had been observed by scanning electron microscopy (SEM). Electrochemical properties of P-MWNT/PANI electrode had been characterized by cyclic voltammetry (CV) and galvanostatic charge-discharge technique. The specific capacitance and long cycle life of P-MWNT-PANI electrode material were both much higher than MWNT/PANI. These interesting results indicate that multi-amino dendrimer, PAMAM, covalently linked on MWNT provides more reaction sites for in-situ polymerization of ordered PANI, which could efficiently shorten the ion diffusion length in electrolytes and lead to making fully use of conducting materials.

  7. Effects of aspect ratio of multi-walled carbon nanotubes on coal washery waste water treatment.

    PubMed

    Aliyu, Ahmed; Kariim, Ishaq; Abdulkareem, Saka Ambali

    2017-11-01

    The dependency of adsorption behaviour on the aspect ratio of multi-walled carbon nanotubes (MWCNTs) has been explored. In this study, effect of growth temperature on yield and aspect ratio of MWCNTs by catalytic chemical vapour deposition (CCVD) method is reported. The result revealed that yield and aspect ratio of synthesised MWCNTs strongly depend on the growth temperature during CCVD operation. The resulting MWCNTs were characterized by High Resolution Transmission Electron Microscope (HRTEM), Dynamic Light Scattering (DLS) and X-ray diffraction (XRD) techniques to determine it diameter, hydrodynamic diameter and crystallinity respectively. Aspect ratio and length of the grown MWCNTs were determined from the HRTEM images with the hydrodynamic diameter using the modified Navier-Stokes and Stokes-Einstein equations. The effect of the prepared MWCNTs dosage were investigated on the Turbidity, Iron (Fe) and Lead (Pb) removal efficiency of coal washery effluent. The MWCNTs with higher length (58.17 μm) and diameter (71 nm) tend to show high turbidity and Fe removal, while MWCNTs with lower length (38.87 μm) and diameter (45 nm) tend to show high removal of Pb. Hence, the growth temperature during CCVD operation shows a great effluence on the aspect ratio of MWCNTs which determines it area of applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Modification of thin-film polyamide membrane with multi-walled carbon nanotubes by interfacial polymerization

    NASA Astrophysics Data System (ADS)

    Al-Hobaib, Abdullah S.; Al-Sheetan, Kh. M.; Shaik, Mohammed Rafi; Al-Suhybani, M. S.

    2017-12-01

    Polyamide thin-film composite (TFC) was fabricated on polysulfone (PS-20) base by interfacial polymerization of aqueous m-phenylenediamine (MPD) solution and 1,3,5-benzenetricarbonyl trichloride (TMC) in hexane organic solution. Multi-wall carbon nanotubes (MWCNT) were carboxylated by heating MWCNT powder in a mixture of HNO3 and H2SO4 (1:3 v/v) at 70 °C under constant sonication for different periods. Polyamide nanocomposites were prepared by incorporating MWCNT and the carboxylated MWCNT (MWCNT-COOH) at different concentrations (0.001-0.009 wt%). The developed composites were analyzed by Fourier transform infrared spectroscopy-attenuated total reflection, scanning electron microscopy, transmission electron microscopy, contact angle measurement, determination of salt rejection and water permeate flux capabilities. The surface morphological studies displayed that the amalgamation of MWCNT considerably changed the surface properties of modified membranes. The surface hydrophilicity was increased as observed in the enhancement in water flux and pure water permeance, due to the presence of hydrophilic nanotubes. Salt rejection was obtained between 94 and 99% and varied water flux values for TFC-reference membrane, pristine-MWCNT in MPD, pristine-MWCNT in TMC and MWCNT-COOH in MPD were 20.5, 38, 40 and 43 L/m2h. The water flux and salt rejection performances revealed that the MWCNT-COOH membrane was superior membrane as compared to the other prepared membranes.

  9. Effect of multi-walled carbon nanotubes on phytotoxicity of sediments contaminated by phenanthrene and cadmium.

    PubMed

    Song, Biao; Zeng, Guangming; Gong, Jilai; Zhang, Peng; Deng, Jiaqin; Deng, Canhui; Yan, Jin; Xu, Piao; Lai, Cui; Zhang, Chen; Cheng, Min

    2017-04-01

    To implement effective control and abatement programs for contaminants accumulating in sediments, strategies are needed for evaluating the quality of amended sediments. In this study, phytotoxicity of the sediments contaminated by cadmium and phenanthrene was evaluated after in situ remediation with multi-walled carbon nanotubes (MWCNTs) as adsorbents. Adsorption experiments and measurement of aqueous concentrations of the contaminants in overlying water were used to investigate the remediation effectiveness from physical and chemical aspects. The results indicated that MWCNTs showed a much better adsorption performance towards phenanthrene and Cd(II) compared with the sediments. The in situ remediation with MWCNTs could distinctly decrease the aqueous concentrations of phenanthrene and Cd(II) released from the sediments, reducing environmental risk towards overlying water. Influences of MWCNTs dose, MWCNTs diameter, and contact time on phtotoxicity of the contaminated sediments were studied. No significant inhibition of the amended sediments on germination of the test species was observed in the experiments, while the root growth was more sensitive than biomass production to the changes of contaminant concentrations. The analysis of Pearson correlation coefficients between evaluation indicators and associated remediation parameters suggested that phytotoxicity of sediments might inaccurately indicate the changes of pollutant content, but it was significant in reflecting the ecotoxicity of sediments after remediation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Adsorption of arsenic on multiwall carbon nanotube-zirconia nanohybrid for potential drinking water purification.

    PubMed

    Ntim, Susana Addo; Mitra, Somenath

    2012-06-01

    The adsorptive removal of arsenic from water using a multiwall carbon nanotube-zirconia nanohybrid (MWCNT-ZrO(2)) is presented. The MWCNT-ZrO(2) with 4.85% zirconia was effective in meeting the drinking water standard levels of 10 μg L(-1). The absorption capacity of the composite were 2000 μg g(-1) and 5000 μg g(-1) for As(III) and As(V) respectively, which were significantly higher than those reported previously for iron oxide coated MWCNTs. The adsorption of As(V) on MWCNT-ZrO(2) was faster than that of As(III), and a pseudo-second order rate equation effectively described the uptake kinetics. The adsorption isotherms for As(III) and As(V) fitted both the Langmuir and Freundlich models. A major advantage of the MWCNT-ZrO(2) was that the adsorption capacity was not a function of pH. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. Palladium-doped-ZrO2-multiwalled carbon nanotubes nanocomposite: an advanced photocatalyst for water treatment

    NASA Astrophysics Data System (ADS)

    Anku, William Wilson; Oppong, Samuel Osei-Bonsu; Shukla, Sudheesh Kumar; Agorku, Eric Selorm; Govender, Poomani Penny

    2016-06-01

    The photocatalytic degradation of organic pollutants from water using palladium-doped-zirconium oxide-multiwalled carbon nanotubes (Pd-ZrO2-MWCNTs) nanocomposites is presented. A series of Pd doped-ZrO2-MWCNTs nanocomposites with varying percentage compositions of Pd were prepared by the homogenous co-precipitation method. The photocatalytic applicability of the materials was investigated by the degradation of acid blue 40 dye in water under simulated solar light. The optical, morphological and structural properties of the nanocomposites were evaluated using X-ray powder diffraction, Fourier transformer infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, BET surface area analysis and (UV-Vis) spectroscopy. The Pd-ZrO2-MWCNTs nanocomposites showed enhanced photocatalytic activity toward the degradation of the acid blue 40 dye under visible light compared with bare ZrO2 and ZrO2-MWCNTs alone. The remarkable photocatalytic activity of Pd-ZrO2-MWCNTs nanocomposites in the visible light makes it an ideal photocatalyst for the removal of organic pollutants in water. The 0.5 % Pd-ZrO2-MWCNT was the most efficient photocatalyst with 98 % degradation after 3 h with corresponding K a and band gap values of 16.8 × 10-3 m-1 and 2.79 eV, respectively.

  12. Comprehensive spectroscopic studies on the interaction of biomolecules with surfactant detached multi-walled carbon nanotubes.

    PubMed

    Sekar, Gajalakshmi; Mukherjee, Amitava; Chandrasekaran, Natarajan

    2015-04-01

    This paper investigates the interaction of ten diverse biomolecules with surfactant detached Multi-Walled Carbon Nanotubes (MWCNTs) using multiple spectroscopic methods. Declining fluorescence intensity of biomolecules in combination with the hyperchromic effect in UV-Visible spectra confirmed the existence of the ground state complex formation. Quenching mechanism remains static and non-fluorescent. 3D spectral data of biomolecules suggested the possibilities of disturbances to the aromatic microenvironment of tryptophan and tyrosine residues arising out of CNTs interaction. Amide band Shifts corresponding to the secondary structure of biomolecules were observed in the of FTIR and FT-Raman spectra. In addition, there exists an increased Raman intensity of tryptophan residues of biomolecules upon interaction with CNTs. Hence, the binding of the aromatic structures of CNTs with the aromatic amino acid residues, in a particular, tryptophan was evidenced. Far UV Circular spectra have showed the loss of alpha-helical contents in biomolecules upon interaction with CNTs. Near UV CD spectra confirmed the alterations in the tryptophan positions of the peptide backbone. Hence, our results have demonstrated that the interaction of biomolecules with OH-MWCNTs would involve binding cum structural changes and alteration to their aromatic micro-environment. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Fabrication of multiwall carbon nanotube sheet based hydrogen sensor on a stacking multi-layer structure.

    PubMed

    Yan, Keyi; Toku, Yuhki; Morita, Yasuyuki; Ju, Yang

    2018-06-22

    In this research, we propose a new simple method to fabricate hydrogen gas sensor by stacking the multiwall carbon nanotube (MWCNT) sheets. MWCNT sheet offers a larger surface area and more CNT contacts, which are key factors for gas sensing, because of its super-high alignment and end-to-end structure comparing to the traditional CNT film. Besides, MWCNT sheet can be directly drawn from the spinnable CNT array in large scales. Therefore, this method is a potential answer for the mass production and commercialization of CNT based sensor with high response. By stacking different layers of sheet, microstructure and CNT interactions in the layers were changed and their influences towards gas sensing were investigated. It was observed that the sample with 3 layers of sheet and functionalized with 3 nm-thick Pd showed the best gas sensing performance with a response of 12.31% at 4% H2 and response time below 200 s. © 2018 IOP Publishing Ltd.

  14. Strengthening behavior of chopped multi-walled carbon nanotube reinforced aluminum matrix composites

    SciTech Connect

    Shin, S.E.; Bae, D.H., E-mail: donghyun@yonsei.ac.kr

    2013-09-15

    Strengthening behavior of the aluminum composites reinforced with chopped multi-walled carbon nanotubes (MWCNTs) or aluminum carbide formed during annealing at 500 °C has been investigated. The composites were fabricated by hot-rolling the powders which were ball-milled under various conditions. During the early annealing process, aluminum atoms can cluster inside the tube due to the diffusional flow of aluminum atoms into the tube, providing an increase of the strength of the composite. Further annealing induces the formation of the aluminum carbide phase, leading to an overall drop in the strength of the composites. While the strength of the composites can bemore » evaluated according to the rule of mixture, a particle spacing effect can be additionally imparted on the strength of the composites reinforced with the chopped MWCNTs or the corresponding carbides since the reinforcing agents are smaller than the submicron matrix grains. - Highlights: • Strengthening behavior of chopped CNT reinforced Al-based composites is investigated. • Chopped CNTs have influenced the strength and microstructures of the composites. • Chopped CNTs are created under Ar- 3% H2 atmosphere during mechanical milling. • Strength can be evaluated by the rule of the mixture and a particle spacing effect.« less

  15. The role of the iron catalyst in the toxicity of multi-walled carbon nanotubes (MWCNTs).

    PubMed

    Visalli, Giuseppa; Facciolà, Alessio; Iannazzo, Daniela; Piperno, Anna; Pistone, Alessandro; Di Pietro, Angela

    2017-09-01

    This study aimed to investigate the role of iron, used as a catalyst, in the biological response to pristine and functionalized multi-walled carbon nanotubes (p/fMWCNTs) with an iron content of 2.5-2.8%. Preliminarily, we assessed the pro-oxidant activity of MWCNTs-associated iron by an abiotic test. To evaluate iron bioavailability, we measured intracellular redox-active iron in A549 cells exposed to both MWCNT suspensions and to the cell medium preconditioned by MWCNTs, in order to assess the iron dissolution rate under physiological conditions. Moreover, in exposed cells, we detected ROS levels, 8-oxo-dG and mitochondrial function. The results clearly highlighted that MWCNTs- associated iron was not redox-active and that iron leakage did not occur under physiological conditions, including the oxidative burst of specialized cells. Despite this, in MWCNTs exposed cells, higher level of intracellular redox-active iron was measured in comparison to control and a significant time-dependent ROS increase was observed (P<0.01). Higher levels of 8-oxo-dG, a marker of oxidative DNA damage, and decreased mitochondrial function, confirmed the oxidative stress induced by MWCNTs. Based on the results we believe that oxidative damage could be attributable to the release of endogenous redox-active iron. This was due to the damage of acidic vacuolar compartment caused by endocytosis-mediated MWCNT internalization. Copyright © 2017 Elsevier GmbH. All rights reserved.

  16. The influence of salinity on the effects of Multi-walled carbon nanotubes on polychaetes.

    PubMed

    De Marchi, Lucia; Neto, Victor; Pretti, Carlo; Figueira, Etelvina; Chiellini, Federica; Morelli, Andrea; Soares, Amadeu M V M; Freitas, Rosa

    2018-06-05

    Salinity shifts in estuarine and coastal areas are becoming a topic of concern and are one of the main factors influencing nanoparticles behaviour in the environment. For this reason, the impacts of multi-walled carbon nanotubes (MWCNTs) under different seawater salinity conditions were evaluated on the common ragworm Hediste diversicolor, a polychaete species widely used as bioindicator of estuarine environmental quality. An innovative method to assess the presence of MWCNT aggregates in the sediments was used for the first time. Biomarkers approach was used to evaluate the metabolic capacity, oxidative status and neurotoxicity of polychaetes after long-term exposure. The results revealed an alteration of energy-related responses in contaminated polychaetes under both salinity conditions, resulting in an increase of metabolism and expenditure of their energy reserves (lower glycogen and protein contents). Moreover, a concentration-dependent toxicity (higher lipid peroxidation, lower ratio between reduced and oxidized glutathione and activation of antioxidant defences and biotransformation mechanisms) was observed in H. diversicolor, especially when exposed to low salinity. Additionally, neurotoxicity was observed by inhibition of Cholinesterases activity in organisms exposed to MWCNTs at both salinities.

  17. Direct comparison of single- and multi-walled carbon nanotubes in fluorescence quenching phenomenon

    NASA Astrophysics Data System (ADS)

    Oura, Shusuke; Umemura, Kazuo

    2018-03-01

    Here, we report the fluorescence quenching ability of single-stranded DNA (ssDNA)-wrapped single- and multi-walled carbon nanotubes (ssDNA-SWNTs and ssDNA-MWNTs, respectively) using fluorescein dye-labeled ssDNA (Fluor-ssDNA). To compare the quenching abilities of SWNTs and MWNTs, we measured the quenching ratios of fluorescence emission from fluorescein when Fluor-ssDNA reacted with the hybrids of 30-mers of thymine (T30) and SWNTs or MWNTs (T30-SWNTs and T30-MWNTs, respectively). The fluorescence quenching ratios of Fluor-T30 in SWNT and MWNT samples were 28 ± 3.1 and 36 ± 2.0% relative to free fluorescein at the same concentration, respectively. On the other hand, those of Fluor-A30 with SWNT and MWNT hybrids were 11 ± 1.9 and 32 ± 1.9%, respectively. Our results suggest that although the fluorescence quenching ability of MWNT was greater than that of SWNT, SWNT quenching ratios were more sensitive to the base sequences of Fluor-ssDNA.

  18. The functionalization and characterization of multi-walled carbon nanotubes (MWCNTs)

    SciTech Connect

    Abdullah, Mohd Pauzi; Center of Water Analysis and Research; Zulkepli, Siti Aminah

    2015-09-25

    Functionalization is the process of introducing chemical functional groups on the surface of the material. In this study, a multi-walled carbon nanotube (MWCNTs) was functionalized by oxidation treatment using concentrated nitric acid. The functionalized and pristine MWCNTs were analyzed by using Fourier Transform Infrared Spectroscopy (FT-IR) and X-Ray Diffraction (XRD). The XRD patterns exhibit the graphitic properties for all samples. Besides, the XRD results also demonstrate that the percent of crystallinity of MWCNTs increases as the duration of acid treatment increases. The percent of crystallinity increases from 66% to 80% when the pristine MWCNT treated for 12 hours with additionalmore » 12 hours reflux process with nitric acid. The IR spectrum for the 12 hours-treated MWCNTs shows the formation of carboxyl functional group. Additional 12 hours reflux process with nitric acid on the 12 hours-treated MWCNTs have shown the loss of existing carboxyl group and only hydroxyl group formed.« less

  19. Enhanced water vapor separation by temperature-controlled aligned-multiwalled carbon nanotube membranes.

    PubMed

    Jeon, Wonjae; Yun, Jongju; Khan, Fakhre Alam; Baik, Seunghyun

    2015-09-14

    Here we present a new strategy of selectively rejecting water vapor while allowing fast transport of dry gases using temperature-controlled aligned-multiwalled carbon nanotubes (aligned-MWNTs). The mechanism is based on the water vapor condensation at the entry region of nanotubes followed by removing aggregated water droplets at the tip of the superhydrophobic aligned-MWNTs. The first condensation step could be dramatically enhanced by decreasing the nanotube temperature. The permeate-side relative humidity was as low as ∼17% and the helium-water vapor separation factor was as high as 4.62 when a helium-water vapor mixture with a relative humidity of 100% was supplied to the aligned-MWNTs. The flow through the interstitial space of the aligned-MWNTs allowed the permeability of single dry gases an order of magnitude higher than the Knudsen prediction regardless of membrane temperature. The water vapor separation performance of hydrophobic polytetrafluoroethylene membranes could also be significantly enhanced at low temperatures. This work combines the membrane-based separation technology with temperature control to enhance water vapor separation performance.

  20. 3D printing of highly elastic strain sensors using polyurethane/multiwall carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Christ, Josef F.; Hohimer, Cameron J.; Aliheidari, Nahal; Ameli, Amir; Mo, Changki; Pötschke, Petra

    2017-04-01

    As the desire for wearable electronics increases and the soft robotics industry advances, the need for novel sensing materials has also increased. Recently, there have been many attempts at producing novel materials, which exhibit piezoresistive behavior. However, one of the major shortcomings in strain sensing technologies is in the fabrication of such sensors. While there is significant research and literature covering the various methods for developing piezoresistive materials, fabricating complex sensor platforms is still a manufacturing challenge. Here, we report a facile method to fabricate multidirectional embedded strain sensors using additive manufacturing technology. Pure thermoplastic polyurethane (TPU) and TPU/multiwall carbon nanotubes (MWCNT) nanocomposites were 3D printed in tandem using a low-cost multi-material FDM printer to fabricate uniaxial and biaxial strain sensors with conductive paths embedded within the insulative TPU platform. The sensors were then subjected to a series of cyclic strain loads. The results revealed excellent piezoresistive responses of the sensors with cyclic repeatability in both the axial and transverse directions and in response to strains as high as 50%. Further, while strain-softening did occur in the embedded printed strain sensors, it was predictable and similar to the results found in the literature for bulk polymer nanocomposites. This works demonstrates the possibility of manufacturing embedded and multidirectional flexible strain sensors using an inexpensive and versatile method, with potential applications in soft robotics and flexible electronics and health monitoring.

  1. Temperature dependence of thermal boundary resistances between multiwalled carbon nanotubes and some typical counterpart materials.

    PubMed

    Zhang, Guang; Liu, Changhong; Fan, Shoushan

    2012-04-24

    We directly measured the temperature dependence of thermal boundary resistances (TBRs) between multiwalled carbon nanotubes (MWCNTs) and different materials at elevated temperatures. Using the steady-state heat flow and the noncontacted measurement method, we could conveniently obtain the TBR-temperature relations. Our results indicate that the TBR-temperature relations vary distinctively with different contact materials when heating temperatures change from about 300 to 450 K; that is, the CNT-metal TBRs increase with increasing temperatures, whereas the CNT-insulator TBRs decrease. As a comparison, the TBRs between superaligned MWCNTs were measured and we found that the CNT-CNT TBRs remain basically unchanged as temperatures increase. We also found that the magnitude of TBRs between MWCNTs and different materials could differ from each other significantly. These results suggest that the choice of the right electrode may have an obvious influence on the thermal properties and other properties of the CNT-based devices. From another perspective, in view of some existing theoretical models about TBRs, our results support the validity of the molecular dynamics (MD) simulations in the calculation of CNT-solid TBRs at elevated temperatures.

  2. Poly(3-hexylthiophene)/multiwalled carbon hybrid coaxial nanotubes: nanoscale rectification and photovoltaic characteristics.

    PubMed

    Kim, Kihyun; Shin, Ji Won; Lee, Yong Baek; Cho, Mi Yeon; Lee, Suk Ho; Park, Dong Hyuk; Jang, Dong Kyu; Lee, Cheol Jin; Joo, Jinsoo

    2010-07-27

    We fabricate hybrid coaxial nanotubes (NTs) of multiwalled carbon nanotubes (MWCNTs) coated with light-emitting poly(3-hexylthiophene) (P3HT). The p-type P3HT material with a thickness of approximately 20 nm is electrochemically deposited onto the surface of the MWCNT. The formation of hybrid coaxial NTs of the P3HT/MWCNT is confirmed by a transmission electron microscope, FT-IR, and Raman spectra. The optical and structural properties of the hybrid NTs are characterized using ultraviolet and visible absorption, Raman, and photoluminescence (PL) spectra where, it is shown that the PL intensity of the P3HT materials decreases after the hybridization with the MWCNTs. The current-voltage (I-V) characteristics of the outer P3HT single NT show the semiconducting behavior, while ohmic behavior is observed for the inner single MWCNT. The I-V characteristics of the hybrid junction between the outer P3HT NT and the inner MWCNT, for the hybrid single NT, exhibit the characteristics of a diode (i.e., rectification), whose efficiency is clearly enhanced with light irradiation. The rectification effect of the hybrid single NT has been analyzed in terms of charge tunneling models. The quasi-photovoltaic effect is also observed at low bias for the P3HT/MWCNT hybrid single NT.

  3. Nanogenerators consisting of direct-grown piezoelectrics on multi-walled carbon nanotubes using flexoelectric effects

    PubMed Central

    Han, Jin Kyu; Jeon, Do Hyun; Cho, Sam Yeon; Kang, Sin Wook; Yang, Sun A.; Bu, Sang Don; Myung, Sung; Lim, Jongsun; Choi, Moonkang; Lee, Minbaek; Lee, Min Ku

    2016-01-01

    We report the first attempt to prepare a flexoelectric nanogenerator consisting of direct-grown piezoelectrics on multi-walled carbon nanotubes (mwCNT). Direct-grown piezoelectrics on mwCNTs are formed by a stirring and heating method using a Pb(Zr0.52Ti0.48)O3 (PZT)-mwCNT precursor solution. We studied the unit cell mismatch and strain distribution of epitaxial PZT nanoparticles, and found that lattice strain is relaxed along the growth direction. A PZT-mwCNT nanogenerator was found to produce a peak output voltage of 8.6 V and an output current of 47 nA when a force of 20 N is applied. Direct-grown piezoelectric nanogenerators generate a higher voltage and current than simple mixtures of PZT and CNTs resulting from the stronger connection between PZT crystals and mwCNTs and an enhanced flexoelectric effect caused by the strain gradient. These experiments represent a significant step toward the application of nanogenerators using piezoelectric nanocomposite materials. PMID:27406631

  4. Alkaline electrochemical advanced oxidation process for chromium oxidation at graphitized multi-walled carbon nanotubes.

    PubMed

    Xue, Yudong; Zheng, Shili; Sun, Zhi; Zhang, Yi; Jin, Wei

    2017-09-01

    Alkaline electrochemical advanced oxidation processes for chromium oxidation and Cr-contaminated waste disposal were reported in this study. The highly graphitized multi-walled carbon nanotubes g-MWCNTs modified electrode was prepared for the in-situ electrochemical generation of HO 2 - . RRDE test results illustrated that g-MWCNTs exhibited much higher two-electron oxygen reduction activity than other nanocarbon materials with peak current density of 1.24 mA cm -2 , %HO 2 - of 77.0% and onset potential of -0.15 V (vs. Hg/HgO). It was originated from the highly graphitized structure and good electrical conductivity as illustrated from the Raman, XRD and EIS characterizations, respectively. Large amount of reactive oxygen species (HO 2 - and ·OH) were in-situ electro-generated from the two-electron oxygen reduction and chromium-induced alkaline electro-Fenton-like reaction. The oxidation of Cr(III) was efficiently achieved within 90 min and the conversion ratio maintained more than 95% of the original value after stability test, offering an efficient and green approach for the utilization of Cr-containing wastes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Carcinogenicity of multi-walled carbon nanotubes: challenging issue on hazard assessment.

    PubMed

    Fukushima, Shoji; Kasai, Tatsuya; Umeda, Yumi; Ohnishi, Makoto; Sasaki, Toshiaki; Matsumoto, Michiharu

    2018-01-25

    This report reviews the carcinogenicity of multi-walled carbon nanotubes (MWCNTs) in experimental animals, concentrating on MWNT-7, a straight fibrous MWCNT. MWCNTs were administered to mice and rats by intraperitoneal injection, intrascrotal injection, subcutaneous injection, intratracheal instillation and inhalation. Intraperitoneal injection of MWNT-7 induced peritoneal mesothelioma in mice and rats. Intrascrotal injection induced peritoneal mesothelioma in rats. Intratracheal instillation of MWCNT-N (another straight fibrous MWCNT) induced both lung carcinoma and pleural mesothelioma in rats. In the whole body inhalation studies, in mice MWNT-7 promoted methylcholanthrene-initiated lung carcinogenesis. In rats, inhalation of MWNT-7 induced lung carcinoma and lung burdens of MWNT-7 increased with increasing concentration of airborne MWNT-7 and increasing duration of exposure. Straight, fibrous MWCNTs exerted carcinogenicity in experimental animals. Phagocytosis of MWCNT fibers by macrophages was very likely to be a principle factor in MWCNT lung carcinogenesis. Using no-observed-adverse-effect level-based approach, we calculated that the occupational exposure limit (OEL) of MWNT-7 for cancer protection is 0.15 μg/m 3 for a human worker. Further studies on the effects of the shape and size of MWCNT fibers and mode of action on the carcinogenicity are required.

  6. Rheological and mechanical properties of polypropylene prepared with multi-walled carbon nanotube masterbatch.

    PubMed

    Shim, Young-Sun; Park, Soo-Jin

    2012-07-01

    In this study, the effects of polypropylene-grafted maleic-anhydride-treated multi-walled carbon nanotubes (PP-MWNTs) on the viscoelastic behaviors and mechanical properties of a polypropylene-(PP)-based composite system were examined. The PP-MWNT/PP composites were prepared via melt mixing with a 3:1 ratio of PP-g-MA and acid-treated MWNTs at 220 degrees C. The surface characteristics of the PP-MWNTs were confirmed via Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). The viscoelastic behavior and mechanical properties of the PP-MWNT/PP composites were confirmed using a rheometer and an ultimate testing machine (UTM). The storage and loss moduli increased with increasing PP-MWNT content. The critical intensity stress factor (K(IC)) of the PP-MWNT/PP composites at high filler loading was also higher than that of the MWNT/PP composites. In conclusion, the viscoelastic behavior and mechanical properties of MWNT/PP can be improved by grafting MWNTs to PP-g-MA.

  7. Electronic excitation induced modifications in elongated iron nanoparticle encapsulated multiwalled carbon nanotubes under ion irradiation

    NASA Astrophysics Data System (ADS)

    Saikiran, V.; Bazylewski, P.; Sameera, I.; Bhatia, Ravi; Pathak, A. P.; Prasad, V.; Chang, G. S.

    2018-05-01

    Multi-wall carbon nanotubes (MWCNT) filled with Fe nanorods were shown to have contracted and deformed under heavy ion irradiation. In this study, 120 MeV Ag and 80 MeV Ni ion irradiation was performed to study the deformation and defects induced in iron filled MWCNT under heavy ion irradiation. The structural modifications induced due to electronic excitation by ion irradiation were investigated employing high-resolution transmission electron microscopy, micro-Raman scattering experiments, and synchrotron-based X-ray absorption and emission spectroscopy. We understand that the ion irradiation causes modifications in the Fe nanorods which result in compressions and expansions of the nanotubes, and in turn leads to the buckling of MWCNT. The G band of the Raman spectra shifts slightly towards higher wavenumber and the shoulder G‧ band enhances with the increase of ion irradiation fluence, where the buckling wavelength depends on the radius 'r' of the nanotubes as exp[(r)0.5]. The intensity ratio of the D to G Raman modes initially decreases at the lowest fluence, and then it increases with the increase in ion fluence. The electron diffraction pattern and the high resolution images clearly show the presence of ion induced defects on the walls of the tube and encapsulated iron nanorods.

  8. Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine.

    PubMed

    Deborah, M; Jawahar, A; Mathavan, T; Dhas, M Kumara; Benial, A Milton Franklin

    2015-03-15

    The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (002) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine

    NASA Astrophysics Data System (ADS)

    Deborah, M.; Jawahar, A.; Mathavan, T.; Dhas, M. Kumara; Benial, A. Milton Franklin

    2015-03-01

    The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (0 0 2) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery.

  10. Damaging Effects of Multi-walled Carbon Nanotubes on Pregnant Mice with Different Pregnancy Times

    NASA Astrophysics Data System (ADS)

    Qi, Wei; Bi, Juanjuan; Zhang, Xiaoyong; Wang, Jing; Wang, Jianjun; Liu, Peng; Li, Zhan; Wu, Wangsuo

    2014-03-01

    The mechanism by which nanoparticles cross the placental barrier was studied by using isotopic tracers. The abortion rates and other related data were counted and analysed in pregnant mice with different pregnancy times. Results showed that oxidised multi-walled carbon nanotubes (oMWCNTs) crossed the placental barrier and entered the foetus body. The abortion rates in the pregnant mice depended on pregnancy times. The abortion rates in the first-time, second-time and fourth-time pregnant mice were 70%, 40% and 50%, respectively. The maternal body weight gain was inhibited until gestational ages of 13, 10 and 11 d. oMWCNTs decreased the serum progesterone level and increased the serum oestradiol level in a dose- and time-dependent manner. However, this effect decreased with gestational age. The histology and vascular endothelial growth factor/reactive oxygen species content in the placenta showed that oMWCNTs narrowed the blood vessel and decreased the number of blood vessels in the placenta.

  11. Removal of virus and toxin using heatable multi-walled carbon nanotube web filters

    NASA Astrophysics Data System (ADS)

    Jang, Hoon-Sik; Jeon, Sang Koo; Ryu, Kwon-Sang; Nahm, Seung Hoon

    2016-02-01

    Many studies have used a carbon nanotube (CNT) filter for pathogen removal and/or inactivation by means of electrochemical or electrochlorination. The large surface area, fine pore size and high electrical and thermal conductivity of CNTs make them suitable and distinct to use for the filtering and removal of pathogens. Here, we grew spin-capable multi-walled CNTs (MWCNTs) and manufactured a web filter using the spun MWCNTs. Botulinum toxin type E light chain (BoT/E-LC) and vaccinia virus (VV) were filtered using the MWCNT web filters and were evaporated and removed by applying direct current (DC) voltage to both sides of the MWCNT webs, excluding electrochemical or electrochlorination. The filtering and removal of BoT/E-LC and VV were performed after seven layers of the MWCNT sheets were coated onto a silicon oxide porous plate. The electrical resistance of the webs in the seven layer sheet was 293 Ω. The temperature of MWCNTs webs was linearly increased to ˜300 °C at 210 V of DC voltage. This temperature was enough to remove BoT/E-LC and VV. From the SEM and XPS results, we confirmed that BoT/E-LC and VV on the MWCNT webs were almost removed by applying a DC voltage and that some element (N, Na, Cl, etc.) as residues on the MWCNT webs remained.

  12. Transport and remobilization of multi-walled carbon nanotubes in porous media during dynamic saturation change

    NASA Astrophysics Data System (ADS)

    Sharma, P.

    2012-04-01

    Nanotechnology is one of the most important technologies in this century and it is evoking a new industrial revolution. Carbon nanotubes (CNTs) are important engineered nanoparticles with unique and beneficial properties. As a result, CNT has been used in a wide range of commercial products including electronics, optical devices and drug delivery leading to their disposal in the natural environment. Literature studies have investigated the mobility of CNTs in saturated porous media under differing physical and chemical conditions. However CNT transport in temporarily changing porous media water content has not been investigated thus far (a common scenario with rainfall/infiltration events in the vadose zone). This study investigated the mobilization of multi-walled CNTs (MCNTs) in repeated wetting and drying cycles with varying flow rates and ionic strength of the inflow solution. Imbibition-drainage-imbibition cycle experiments suggest that MCNTs mobilization increased with increase in flow rates. MCNTs mobilization occurred only with first imbibition events at low ionic strengths however less mobilization happened for higher ionic strength inflow solution in the first imbibition cycle and additional MCNTs were found in the outflow solution in second imbibition cycle, using low ionic strength solution. This observation was likely due to the attachment force between MCNTs and sand surface. Most of the MCNT mobilization occurred during liquid-gas interface movement with less chance of MCNTs to jump the energy barrier at higher ionic strength solution. As a result, less detachment of MCNTs occurred from the sand surface during drainage.

  13. Electromechanical Behavior of Chemically Reduced Graphene Oxide and Multi-walled Carbon Nanotube Hybrid Material

    NASA Astrophysics Data System (ADS)

    Benchirouf, Abderrahmane; Müller, Christian; Kanoun, Olfa

    2016-01-01

    In this paper, we propose strain-sensitive thin films based on chemically reduced graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) without adding any further surfactants. In spite of the insulating properties of the thin-film-based GO due to the presence functional groups such as hydroxyl, epoxy, and carbonyl groups in its atomic structure, a significant enhancement of the film conductivity was reached by chemical reduction with hydro-iodic acid. By optimizing the MWCNT content, a significant improvement of electrical and mechanical thin film sensitivity is realized. The optical properties and the morphology of the prepared thin films were studied using ultraviolet-visible spectroscopy (UV-Vis) and scanning electron microscope (SEM). The UV-Vis spectra showed the ability to tune the band gap of the GO by changing the MWCNT content, whereas the SEM indicated that the MWCNTs were well dissolved and coated by the GO. Investigations of the piezoresistive properties of the hybrid nanocomposite material under mechanical load show a linear trend between the electrical resistance and the applied strain. A relatively high gauge factor of 8.5 is reached compared to the commercial metallic strain gauges. The self-assembled hybrid films exhibit outstanding properties in electric conductivity, mechanical strength, and strain sensitivity, which provide a high potential for use in strain-sensing applications.

  14. Electromechanical Behavior of Chemically Reduced Graphene Oxide and Multi-walled Carbon Nanotube Hybrid Material.

    PubMed

    Benchirouf, Abderrahmane; Müller, Christian; Kanoun, Olfa

    2016-12-01

    In this paper, we propose strain-sensitive thin films based on chemically reduced graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) without adding any further surfactants. In spite of the insulating properties of the thin-film-based GO due to the presence functional groups such as hydroxyl, epoxy, and carbonyl groups in its atomic structure, a significant enhancement of the film conductivity was reached by chemical reduction with hydro-iodic acid. By optimizing the MWCNT content, a significant improvement of electrical and mechanical thin film sensitivity is realized. The optical properties and the morphology of the prepared thin films were studied using ultraviolet-visible spectroscopy (UV-Vis) and scanning electron microscope (SEM). The UV-Vis spectra showed the ability to tune the band gap of the GO by changing the MWCNT content, whereas the SEM indicated that the MWCNTs were well dissolved and coated by the GO. Investigations of the piezoresistive properties of the hybrid nanocomposite material under mechanical load show a linear trend between the electrical resistance and the applied strain. A relatively high gauge factor of 8.5 is reached compared to the commercial metallic strain gauges. The self-assembled hybrid films exhibit outstanding properties in electric conductivity, mechanical strength, and strain sensitivity, which provide a high potential for use in strain-sensing applications.

  15. Size response of an SMPS-APS system to commercial multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Bok; Lee, Jun-Hyun; Bae, Gwi-Nam

    2010-02-01

    Carbon nanotubes (CNTs) are representative-engineered nanomaterials with unique properties. The safe production of CNTs urgently requires reliable tools to assess inhalation exposure. In this study, on-line aerosol instruments were employed to detect the release of multi-walled CNTs (MWCNTs) in workplace environments. The size responses of aerosol instruments consisting of both a scanning mobility particle sizer (SMPS) and an aerodynamic particle sizer (APS) were examined using five types of commercial MWCNTs. A MWCNT solution and powder were aerosolized using atomizing and shaking methods, respectively. Regardless of the phase and purity, the aerosolized MWCNTs showed consistent size distributions with both SMPS and APS. The SMPS and APS measurements revealed a dominant broad peak at approximately 200-400 nm and a distinct narrow peak at approximately 2 μm, respectively. Comparing with field application of the two aerosol instruments, the APS response could be a fingerprint of the MWCNTs in a real workplace environment. A modification of the atomizing method is recommended for the long-term inhalation toxicity studies.

  16. Optical properties of ordered vertical arrays of multi-walled carbon nanotubes from FDTD simulations.

    PubMed

    Bao, Hua; Ruan, Xiulin; Fisher, Timothy S

    2010-03-15

    A finite-difference time-domain (FDTD) method is used to model thermal radiative properties of vertical arrays of multi-walled carbon nanotubes (MWCNT). Individual CNTs are treated as solid circular cylinders with an effective dielectric tensor. Consistent with experiments, the results confirm that CNT arrays are highly absorptive. Compared with the commonly used Maxwell-Garnett theory, the FDTD calculations generally predict larger reflectance and absorbance, and smaller transmittance, which are attributed to the diffraction and scattering within the cylinder array structure. The effects of volume fraction, tube length, tube distance, and incident angle on radiative properties are investigated systematically. Low volume fraction and long tubes are more favorable to achieve low reflectance and high absorbance. For a fixed volume fraction and finite tube length, larger periodicity results in larger reflectance and absorbance. The angular dependence studies reveal an optimum incident angle at which the reflectance can be minimized. The results also suggest that an even darker material could be achieved by using CNTs with good alignment on the top surface.

  17. A novel flexible nanogenerator made of ZnO nanoparticles and multiwall carbon nanotube.

    PubMed

    Sun, Hui; Tian, He; Yang, Yi; Xie, Dan; Zhang, Yu-Chi; Liu, Xuan; Ma, Shuo; Zhao, Hai-Ming; Ren, Tian-Ling

    2013-07-07

    In this paper, a novel flexible nanogenerator (FNG) made of zinc-oxide (ZnO) nanoparticles (NPs) and multiwall-carbon nanotubes (MW-CNTs) is presented. In this structure, ZnO NPs and MW-CNTs are mixed with polydimethylsiloxane (PDMS) uniformly to form an entire flexible nanogenerator. Serial tests illustrate that the output voltage and power density are as high as 7.5 V and 18.75 μW per cycle, respectively. Furthermore, by foot stamp on the FNG, a peak voltage as high as 30 V can be generated. Comparing to the control samples, it is also proved that adding MW-CNTs into the matrix could significantly enhance the output voltage from 0.8 to 7.5 V. In summary, our work indicates that the realization of flexible nanogenerators made of ZnO NPs and MW-CNTs is technologically feasible, which may bring out some important and interesting applications in energy harvesting.

  18. Electrical conductivity and piezoresistive response of 3D printed thermoplastic polyurethane/multiwalled carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Hohimer, Cameron J.; Petrossian, Gayaneh; Ameli, Amir; Mo, Changki; Pötschke, Petra

    2018-03-01

    Additive manufacturing (AM) is an emerging field experiencing rapid growth. This paper presents a feasibility study of using fused-deposition modeling (FDM) techniques with smart materials to fabricate objects with sensing and actuating capabilities. The fabrication of objects with sensing typically requires the integration and assembly of multiple components. Incorporating sensing elements into a single FDM process has the potential to significantly simplify manufacturing. The integration of multiple materials, especially smart materials and those with multi-functional properties, into the FDM process is challenging and still requires further development. Previous works by the authors have demonstrated a good printability of thermoplastic polyurethane/multiwall carbon nanotubes (TPU/MWCNT) while maintaining conductivity and piezoresistive response. This research explores the effects of layer height, nozzle temperature, and bed temperature on the electrical conductivity and piezoresistive response of printed TPU/MWCNT nanocomposites. An impedance analyzer was used to determine the conductivity of printed samples under different printing conditions from 5Hz-13MHz. The samples were then tested under compression loads to measure the piezoresistive response. Results show the conductivity and piezoresistive response are only slightly affected by the print parameters and they can be largely considered independent of the print conditions within the examined ranges of print parameters. This behavior simplifies the printing process design for TPU/MWCNT complex structures. This work demonstrates the possibility of manufacturing embedded and multidirectional flexible strain sensors using an inexpensive and versatile method, with potential applications in soft robotics, flexible electronics, and health monitoring.

  19. Development of multi-walled carbon nanotubes reinforced monetite bionanocomposite cements for orthopedic applications.

    PubMed

    Boroujeni, Nariman Mansoori; Zhou, Huan; Luchini, Timothy J F; Bhaduri, Sarit B

    2013-10-01

    In this study, we present results of our research on biodegradable monetite (DCPA, CaHPO4) cement with surface-modified multi-walled carbon nanotubes (mMWCNTs) as potential bone defect repair material. The cement pastes showed desirable handling properties and possessed a suitable setting time for use in surgical setting. The incorporation of mMWCNTs shortened the setting time of DCPA and increased the compressive strength of DCPA cement from 11.09±1.85 MPa to 21.56±2.47 MPa. The cytocompatibility of the materials was investigated in vitro using the preosteoblast cell line MC3T3-E1. An increase of cell numbers was observed on both DCPA and DCPA-mMWCNTs. Scanning electron microscopy (SEM) results also revealed an obvious cell growth on the surface of the cements. Based on these results, DCPA-mMWCNTs composite cements can be considered as potential bone defect repair materials. © 2013.

  20. The construction of glucose biosensor based on platinum nanoclusters-multiwalled carbon nanotubes nanocomposites.

    PubMed

    Wang, Cheng Yan; Tan, Xing Rong; Chen, Shi Hong; Hu, Fang Xin; Zhong, Hua An; Zhang, Yu

    2012-02-01

    One-step synthesis method was proposed to obtain the nanocomposites of platinum nanoclusters and multiwalled carbon nanotubes (PtNCs-MWNTs), which were used as a novel immobilization matrix for the enzyme to fabricate glucose biosensor. The fabrication process of the biosensor was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, atomic force microscopy and scanning electron microscope. Due to the favorable characteristic of PtNCs-MWNTs nanocomposites, the biosensor exhibited good characteristics, such as wide linear range (3.0 μM-12.1 mM), low detection limit (1.0 μM), high sensitivity (12.8 μA mM⁻¹), rapid response time (within 6 s). The apparent Michaelis-Menten constant (K(app)(m)) is 2.1 mM. The performance of the resulting biosensor is more prominent than that of most of the reported glucose biosensors. Furthermore, it was demonstrated that this biosensor can be used for the assay of glucose in human serum samples.

  1. Bienzyme system for the biocatalyzed deposition of polyaniline templated by multiwalled carbon nanotubes: a biosensor design.

    PubMed

    Sheng, Qinglin; Zheng, Jianbin

    2009-02-15

    A novel method based on covalent attachment of two enzymes, glucose oxidase (GOD) and horseradish peroxide (HRP), onto carboxylic-derived multiwalled carbon nanotubes (MWNTs) for the deposition of electroactive polyaniline (PANI) under ambient conditions is described. Ultraviolet-visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and transmission electron microscopy were used to characterize the assembling of bienzyme and the morphology of PANI|MWNTs. Under the bienzyme biocatalytic condition, a head-to-tail structure of PANI templated by MWNTs was formed. The voltammetric characteristics of the resulting biosensor were investigated by cyclic voltammetry in the presence of glucose. The current response of PANI was linearly related to glucose concentration between 0.05 and 12.0mM with a correlation coefficient of 0.994. The synergistic performance of bienzyme, highly efficient polymerization, and templated deposition provide a general platform for the synthesis of nanowires and nanocircuits, the construction of bioelectronic devices, and the design of novel biosensors.

  2. Anodic stripping voltammetric determination of mercury using multi-walled carbon nanotubes film coated glassy carbon electrode.

    PubMed

    Yi, Hongchao

    2003-10-01

    An electrochemical method for the determination of trace levels of mercury based on a multi-walled carbon nanotubes (MWNT) film coated glassy carbon electrode (GCE) is described. In 0.1 mol L(-1) HCl solution containing 0.02 mol L(-1) KI, Hg(2+) was firstly preconcentrated at the MWNT film and then reduced at -0.60 V. During the anodic potential sweep, reduced mercury was oxidized, and then a sensitive and well-defined stripping peak at about -0.20 V appeared. Under identical conditions, a MWNT film coated GCE greatly enhances the stripping peak current of mercury in contrast to a bare GCE. Low concentrations of I(-) remarkably improve the determining sensitivity, since this increases the accumulation efficiency of Hg(2+) at the MWNT film coated GCE. The stripping peak current is proportional to the concentration of Hg(2+) over the range 8 x 10(-10)-5 x 10(-7) mol L(-1). The lowest detectable concentration of Hg(2+) is 2 x 10(-10) mol L(-1) at 5 min accumulation. The relative standard deviation (RSD) at 1 x 10(-8) mol L(-1) Hg(2+) was about 6% ( n=10). By using this proposed method, Hg(2+) in some water samples was determined, and the results were compared with those obtained by atomic absorption spectrometry (AAS). The two results are similar, suggesting that the MWNT-film coated GCE has great potential in practical analysis.

  3. Rapid detection of ssDNA and RNA using multi-walled carbon nanotubes modified screen-printed carbon electrode.

    PubMed

    Ye, Yongkang; Ju, Huangxian

    2005-11-15

    A method for rapid sensitive detection of DNA or RNA was designed using a composite screen-printed carbon electrode modified with multi-walled carbon nanotubes (MWNTs). MWNTs showed catalytic characteristics for the direct electrochemical oxidation of guanine or adenine residues of signal strand DNA (ssDNA) and adenine residues of RNA, leading to indicator-free detection of ssDNA and RNA concentrations. With an accumulation time of 5 min, the proposed method could be used for detection of calf thymus ssDNA ranging from 17.0 to 345 microg ml(-1) with a detection limit of 2.0 microg ml(-1) at 3 sigma and yeast tRNA ranging from 8.2 microg ml(-1) to 4.1 mg ml(-1). AC impedance was employed to characterize the surface of modified electrodes. The advantages of convenient fabrication, low-cost detection, short analysis time and combination with nanotechnology for increasing the sensitivity made the subject worthy of special emphasis in the research programs and sources of new commercial products.

  4. Sorption of carbamazepine by commercial graphene oxides: a comparative study with granular activated carbon and multiwalled carbon nanotubes.

    PubMed

    Cai, Nan; Larese-Casanova, Philip

    2014-07-15

    Graphene nanosheet materials represent a potentially new high surface area sorbent for the treatment of endocrine disrupting compounds (EDCs) in water. However, sorption behavior has been reported only for laboratory graphene prepared by a laborious and hazardous graphite exfoliation process. A careful examination of commercially available, clean, high-volume produced graphene materials should reveal whether they are appropriate for sorbent technologies and which physicochemical properties most influence sorption performance. In this study, three commercially available graphene oxide powders of various particle sizes, specific surface areas, and surface chemistries were evaluated for their sorption performance using carbamazepine and nine other EDCs and were compared to that of conventional granular activated carbon (GAC) and multi-walled carbon nanotubes (MWCNTs). Sorption kinetics of carbamazepine on graphene oxide powders was rapid and reversible with alcohol washing, consistent with π-π interactions. The various sorption extents as described by Freundlich isotherms were best explained by available surface area, and only the highest surface area graphene oxide (771 m(2)/g) out-performed GAC and MWCNTs. Increasing pH caused more negative surface charge, a twofold decrease in sorption of anionic ibuprofen, a onefold increase in sorption of cationic atenolol, and no change for neutral carbamazepine, highlighting the role of electrostatic interactions. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Adsorption of Reactive Red M-2BE dye from water solutions by multi-walled carbon nanotubes and activated carbon.

    PubMed

    Machado, Fernando M; Bergmann, Carlos P; Fernandes, Thais H M; Lima, Eder C; Royer, Betina; Calvete, Tatiana; Fagan, Solange B

    2011-09-15

    Multi-walled carbon nanotubes and powdered activated carbon were used as adsorbents for the successful removal of Reactive Red M-2BE textile dye from aqueous solutions. The adsorbents were characterised by infrared spectroscopy, N(2) adsorption/desorption isotherms and scanning electron microscopy. The effects of pH, shaking time and temperature on adsorption capacity were studied. In the acidic pH region (pH 2.0), the adsorption of the dye was favourable using both adsorbents. The contact time to obtain equilibrium at 298K was fixed at 1h for both adsorbents. The activation energy of the adsorption process was evaluated from 298 to 323K for both adsorbents. The Avrami fractional-order kinetic model provided the best fit to the experimental data compared with pseudo-first-order or pseudo-second-order kinetic adsorption models. For Reactive Red M-2BE dye, the equilibrium data were best fitted to the Liu isotherm model. Simulated dyehouse effluents were used to check the applicability of the proposed adsorbents for effluent treatment. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. An amperometric hydrogen peroxide biosensor based on Co3O4 nanoparticles and multiwalled carbon nanotube modified glassy carbon electrode

    NASA Astrophysics Data System (ADS)

    Kaçar, Ceren; Dalkiran, Berna; Erden, Pınar Esra; Kiliç, Esma

    2014-08-01

    In this work a new type of hydrogen peroxide biosensor was fabricated based on the immobilization of horseradish peroxidase (HRP) by cross-linking on a glassy carbon electrode (GCE) modified with Co3O4 nanoparticles, multiwall carbon nanotubes (MWCNTs) and gelatin. The introduction of MWCNTs and Co3O4 nanoparticles not only enhanced the surface area of the modified electrode for enzyme immobilization but also facilitated the electron transfer rate, resulting in a high sensitivity of the biosensor. The fabrication process of the sensing surface was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Amperometric detection of hydrogen peroxide was investigated by holding the modified electrode at -0.30 V (vs. Ag/AgCl). The biosensor showed optimum response within 5 s at pH 7.0. The optimized biosensor showed linear response range of 7.4 × 10-7-1.9 × 10-5 M with a detection limit of 7.4 × 10-7. The applicability of the purposed biosensor was tested by detecting hydrogen peroxide in disinfector samples. The average recovery was calculated as 100.78 ± 0.89.

  7. Influence of Oxygen Adsorption on the Thermoelectric Power (tep) in Multiwalled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Savage, Traig; Bhattacharya, Sriparna; Sadanadan, Bindu; Gaillard, Jay; Tritt, Terry; Rao, Apparao; Sun, Ya-Ping

    2002-03-01

    The sign of the thermoelectric power (TEP) has been found to be extremely sensitive to oxygen adsorption in single walled carbon nanotube (SWNT) bundles [1-3]. A TEP value of ~ +54 μV/K has been reported in SWNT bundles that were exposed to room air, and upon desorbing the oxygen from the sample, the TEP switches reversibly to ~ -44 μV/K [2]. In this study we report TEP measurements in multiwalled carbon nanotubes (MWNTs) as functions of exposure time to room air (oxygen). The MWNTs were prepared on quartz substrates from a thermal decomposition of xylene-ferrocene mixtures at ~750^oC. Negative TEP values at all temperatures (10-300K) were obtained in freshly prepared MWNTs. Upon exposure of the MWNT film to room air and room light over a period of ~1 month, the TEP is found to change systematically to positive values. We also exposed another MWNT sample to ultraviolet (UV) radiation (λ=240 nm; ~1 W/m^2) in air for 10 days. The data indicates a photo-enhanced adsorption of oxygen as evidenced by a faster (factor of ~3) TEP sign reversal. The TEP in both the air- and UV-exposed films was shown to be completely reversible upon degassing the samples for ~12 hours. These findings are consistent with those reported in SWNT bundles, and a theoretical basis for the photo-induced oxygen adsorption will be presented. [1] P. G. Collins et al., Science, 287, 1804 (2000). [2] G. U. Sumanasekera et al., Phys. Rev. Lett., 85, 1096 (2000). [3] K. Bradley et al., Phys. Rev. Lett., 85, 4361 (2000).

  8. Modifications of Graphite and Multiwall Carbon Nanotubes in the Presence of Urea

    NASA Astrophysics Data System (ADS)

    Duraia, El-Shazly M.; Fahami, Abbas; Beall, Gary W.

    2018-02-01

    The effect of high-energy ball milling on two carbon allotropes, graphite and multiwall carbon nanotubes (MWCNT) in the presence of urea has been studied. Samples were investigated using Raman spectroscopy, x-ray diffraction, scanning electron microscope (SEM) and x-ray photoelectron spectroscopy (XPS). Nitrogen-doped graphene has been successfully synthesized via a simple scalable mechanochemistry method using urea and graphite powder precursors. XPS results revealed the existence of the different nitrogen atoms configurations including pyridine, pyrrodic and graphitic N. SEM observations showed that the graphene nanosheets morphology become more wrinkles folded and crumbled as the milling time increased. The ID/IG ratio also increased as the milling time rose. The presence of both D' and G + D bands at 1621 cm-1 and 2940 cm-1, respectively, demonstrated the nitrogen incorporation in the graphene lattice Two factors contribute to the used urea: first it helps to exfoliate graphite into graphene, and second it preserves the graphitic structure from damage during the milling process as well as acting as a solid-state nitrogen source. Based on the phase analysis, the d-spacing of MWCNT samples in the presence of urea decreased due to the mechanical force in the milling process as the milling time increased. On the other hand, in the graphite case, due to its open flat surface, the graphite (002) peak shifts toward lower two theta as the milling time increase. Such findings are important and could be used for large-scale production of N-doped graphene, diminishing the use of either dangerous chemicals or sophisticated equipment.

  9. Health surveillance study of workers who manufacture multi-walled carbon nanotubes.

    PubMed

    Lee, Jong Seong; Choi, Young Chul; Shin, Jae Hoon; Lee, Ji Hyun; Lee, Yurim; Park, So Young; Baek, Jin Ee; Park, Jung Duck; Ahn, Kangho; Yu, Il Je

    2015-01-01

    While many in vivo and in vitro toxicology studies of multi-walled carbon nanotubes (MWCNTs) have already indicated that exposure to MWCNTs can potentially induce health effects in humans, the actual health effects of MWCNTs among exposed workers are not yet known. Moreover, the levels of exposure and internal doses of MWCNTs are becoming more and more important for estimating the health effects resulting from exposure to MWCNTs. However, information on biomonitoring and exposure to MWCNTs remains limited. Therefore, the authors conducted a health surveillance study in a workplace that manufactures MWCNTs, including assessment of the personal and area exposure levels to MWCNTs, a walk-through evaluation of the manufacturing process, and collection of blood and exhaled breath condensates (EBCs) from the MWCNT manufacturing and office workers. In addition, a pulmonary function test was also conducted on the MWCNT manufacturing workers (9) and office workers (4). The worker exposure to elemental carbon was found to be 6.2-9.3 μg/m(3) in the personal samplings and 5.5-7.3 μg/m(3) in the area samplings. Notwithstanding, the workers exhibited a normal range of hematology and blood biochemistry values and normal lung function parameters. When analyzing the EBCs, the malondialdehyde (MDA), 4-hydroxy-2-hexenal (4-HHE) and n-hexanal levels in the MWCNT manufacturing workers were significantly higher than those in the office workers. The MDA and n-hexanal levels were also significantly correlated with the blood molybdenum concentration, suggesting MDA, n-hexanal and molybdenum as useful biomarkers of MWCNT exposure.

  10. Occupational Exposure to Multi-Walled Carbon Nanotubes During Commercial Production Synthesis and Handling

    PubMed Central

    Kuijpers, Eelco; Bekker, Cindy; Fransman, Wouter; Brouwer, Derk; Tromp, Peter; Vlaanderen, Jelle; Godderis, Lode; Hoet, Peter; Lan, Qing; Silverman, Debra; Vermeulen, Roel; Pronk, Anjoeka

    2016-01-01

    The world-wide production of carbon nanotubes (CNTs) has increased substantially in the last decade, leading to occupational exposures. There is a paucity of exposure data of workers involved in the commercial production of CNTs. The goals of this study were to assess personal exposure to multi-walled carbon nanotubes (MWCNTs) during the synthesis and handling of MWCNTs in a commercial production facility and to link these exposure levels to specific activities. Personal full-shift filter-based samples were collected, during commercial production and handling of MWCNTs, R&D activities, and office work. The concentrations of MWCNT were evaluated on the basis of EC concentrations. Associations were studied between observed MWCNT exposure levels and location and activities. SEM analyses showed MWCNTs, present as agglomerates ranging between 200nm and 100 µm. Exposure levels of MWCNTs observed in the production area during the full scale synthesis of MWCNTs (N = 23) were comparable to levels observed during further handling of MWCNTs (N = 19): (GM (95% lower confidence limit–95% upper confidence limit)) 41 μg m−3 (20–88) versus 43 μg m−3 (22–86), respectively. In the R&D area (N = 11) and the office (N = 5), exposure levels of MWCNTs were significantly (P < 0.05) lower: 5 μg m−3 (2–11) and 7 μg m−3 (2–28), respectively. Bagging, maintenance of the reactor, and powder conditioning were associated with higher exposure levels in the production area, whereas increased exposure levels in the R&D area were related to handling of MWCNTs powder. PMID:26613611

  11. Histopathological alterations in the gills of Nile tilapia exposed to carbofuran and multiwalled carbon nanotubes.

    PubMed

    Campos-Garcia, Janaína; Martinez, Diego Stéfani Teodoro; Rezende, Karina Fernandes Oliveira; da Silva, José Roberto Machado Cunha; Alves, Oswaldo Luiz; Barbieri, Edison

    2016-11-01

    Carbofuran is a nematicide insecticide with a broad spectrum of action. Carbofuran has noxious effects in several species and has been banned in the USA and Europe; however, it is still used in Brazil. Aquatic organisms are not only exposed to pesticides but also to manufactured nanoparticles, and the potential interaction of these compounds therefore requires investigation. The aim of this study was to examine the histopathological alterations in the gills of Nile tilapia (Oreochromis niloticus) to determine possible effects of exposure to carbofuran, nitric acid-treated multiwalled carbon nanotubes (HNO3-MWCNTs) and the combination of carbofuran with nanotubes. Juvenile fish were exposed to different concentrations of carbofuran (0.1, 0.5, 2.0, 4.0 and 8.0mg/L), different concentrations of HNO3-MWCNTs (0.5, 1.0 and 2.0mg/L) or different concentrations of carbofuran (0.1, 0.5, 2.0, 4.0 and 8.0mg/L) with 1.0mg/L of HNO3-MWCNTs. After 24h of exposure, the animals were removed from the aquarium, the spinal cord was transversely sectioned, and the second gill arch was removed for histological evaluation. Common histological changes included dislocation of the epithelial cells, hyperplasia of the epithelial cells along the secondary lamellae, aneurism, and dilation and disarrangement of the capillaries. All the groups exposed to carbofuran demonstrated a dose-dependent correlation in the Histological Alteration Index; the values found for carbofuran and carbon nanotubes were up to 25% greater than for carbofuran alone. This result indicates an interaction between these toxicants, with enhanced ecotoxic effects. This work contributes to the understanding of the environmental impacts of nanomaterials on aquatic organisms, which is necessary for the sustainable development of nanotechnologies. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Magnetic multiwalled carbon nanotubes as nanocarrier tags for sensitive determination of fetuin in saliva.

    PubMed

    Sánchez-Tirado, Esther; González-Cortés, Araceli; Yáñez-Sedeño, Paloma; Pingarrón, José M

    2018-08-15

    This paper reports the development and performance of an electrochemical immunosensor using magnetic multiwalled carbon nanotubes (m-MWCNTs) as nanocarrier tags for the determination of human fetuin A (HFA), a relevant biomarker of obesity, insulin resistance, and type-2 diabetes as well as for pancreatic and liver cancers and inflammatory processes. Screen-printed carbon electrodes were grafted with p-aminobezoic acid and streptavidin was covalently immobilized on the electrode surface. A biotinylated capture antibody was immobilized through streptavidin-biotin interaction and a sandwich assay configuration was implemented using m-MWCNTs conjugated with HRP and anti-HFA antibodies as the detection label. The determination of HFA was accomplished by measuring the current produced by the electrochemical reduction of benzoquinone at -200 mV upon addition of H 2 O 2 as HRP substrate. The prepared m-MWCNTs were characterized by SEM, TEM, XRD and EDS. All the steps involved in the immunosensor preparation were monitored by electrochemical impedance spectroscopy and cyclic voltammetry. A linear calibration plot for HFA was found between 20 and 2000 pg/mL with a LOD value of 16 pg/mL. This performance is notably better than that reported for an ELISA kit and a chronoimpedimetric immunosensor. The favorable contribution of m-MWCNTs in comparison with MWCNTs without incorporated magnetic particles to this excellent analytical performance is also highlighted. The immunosensor selectivity against other proteins and potentially interfering compounds was excellent. In addition, the usefulness of the immunosensor was demonstrated by the analysis of HFA in saliva with minimal sample treatment. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Functionalized Multiwalled Carbon Nanotube Electrochemical Sensor for Determination of Anticancer Drug Flutamide

    NASA Astrophysics Data System (ADS)

    Farias, Julianna Santos; Zanin, Hudson; Caldas, Adriana Silva; dos Santos, Clenilton Costa; Damos, Flavio Santos; de Cássia Silva Luz, Rita

    2017-10-01

    An electrochemical sensor based on functionalized multiwalled carbon nanotubes (MWCNTf) has been developed and applied for determination of anticancer drug flutamide in pharmaceutical and artificial urine samples. The electrode was prepared by modifying a glassy carbon electrode with MWCNTf, denoted herein as MWCNTf/GCE. The MWCNTf/GCE electrode exhibited high catalytic activity, high sensitivity, and high stability and was applicable over a wide concentration range for flutamide. The effects of the scan rate, pH, and nature of the electrolyte on the electrochemical behavior of flutamide on the MWCNTf/GCE were investigated. The results showed that this electrode presented the best square-wave voltammetric response to flutamide in Britton-Robinson buffer solution at pH 5.0 at frequency of 50 Hz and amplitude of 0.06 V. The proposed sensor presents a wide linear response range from concentration of 0.1 μmol L-1 up to 1000 μmol L-1 (or 27.6 μg L-1 up to 0.27 g L-1), with limit of detection, limit of quantification, and sensitivity of 0.03 μmol L-1, 0.1 μmol L-1, and 0.30 μA μmol-1 L, respectively. The MWCNTf/GCE electrode was successfully applied for determination of flutamide in pharmaceutical formulations and artificial urine samples, giving results in agreement with those obtained by a comparative method described in literature. A paired Student's t-test revealed no statistical difference between the reference and proposed method at 95% confidence level. The average recovery for fortified samples was 101 ± 1%.

  14. Photocatalytic activity of porous multiwalled carbon nanotube-TiO2 composite layers for pollutant degradation.

    PubMed

    Zouzelka, Radek; Kusumawati, Yuly; Remzova, Monika; Rathousky, Jiri; Pauporté, Thierry

    2016-11-05

    TiO2 nanoparticles are suitable building blocks nanostructures for the synthesis of porous functional thin films. Here we report the preparation of films using brookite, P25 titania and anatase pristine nanoparticles and of nanocomposite layers combining anatase nanoparticles and multi-walled carbon nanotube (MWCNT) at various concentrations. The structure and phase composition of the layers were characterized by X-ray diffraction and Raman spectroscopy. Their morphology and texture properties were determined by scanning electron microscopy and krypton adsorption experiments, respectively. Additionally to a strong absorption in the UV range, the composites exhibited light absorption in the visible range as well. The photocatalytic performance of the layers was tested in the degradation of aqueous solutions of 4-chlorophenol serving as a model of an eco-persistent pollutant. Besides the determination of the decrease in the concentration of 4-chlorophenol, also the formation of intermediate degradation products, namely hydroquinone and benzoquinone, was followed. The presence of MWCNTs had a beneficial effect on the photocatalytic performance, a marked increase in the photocatalytic degradation rate constant being observed even at very low concentrations of MWCNTs. Compared to a P25 reference layer, the first order rate reaction constant increased by about 100% for the composite films containing MWCNTs at concentrations above 0.6 wt%. The key parameters for the enhancement of the photocatalytic performance are discussed. The presence of carbon nanotubes influences beneficially the degradation of 4-chlorophenol by an attack of the primarily photoproduced hydroxyl radicals onto the 4-chlorophenol molecules. The degradation due to the direct charge transfer is practically not influenced at all. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Multi-walled carbon nanotube structural instability with/without metal nanoparticles under electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Khan, Imran; Huang, Shengli; Wu, Chenxu

    2017-12-01

    The structural transformation of multi-walled carbon nanotubes (MWCNT) under electron beam (e-beam) irradiation at room temperature is studied, with respect to a novel passivation effect due to gold nanoparticles (Au NPs). MWCNT structural evolution induced by energetic e-beam irradiation leads to faster shrinkage, as revealed via in situ transmission electron microscopy, while MWCNT surface modification with Au NPs (Au-MWCNT) slows down the shrinkage by impeding the structural evolution process for a prolonged time under the same irradiation conditions. The new relationship between MWCNT and Au-MWCNT shrinking radii and irradiation time illustrates that the MWCNT shrinkage rate is faster than either theoretical predictions or the same process in Au-MWCNTs. As compared with the outer surface energy (positive curvature), the inner surface energy (negative curvature) of the MWCNT contributes more to the athermal evaporation of tube wall atoms, leading to structural instability and shrinkage under e-beam irradiation. Conversely, Au NPs possess only outer surface energy (positive curvature) compared with the MWCNT. Their presence on MWCNT surfaces retards the dynamics of MWCNT structural evolution by slowing down the evaporation process of carbon atoms, thus restricting Au-MWCNT shrinkage. Au NP interaction and growth evolves athermally on MWCNT surfaces, exhibits increase in their size, and indicates the association of this mechanism with the coalescence induced by e-beam activated electronic excitations. Despite their growth, Au NPs show extreme structural stability, and remain crystalline under prolonged irradiation. It is proposed that the surface energy of MWCNTs and Au NPs, together with e-beam activated soft modes or lattice instability effects, predominantly govern all the above varieties of structural evolution.

  16. Study on effects of E-glass fiber hybrid composites enhanced with multi-walled carbon nanotubes under tensile load using full factorial design of experiments

    NASA Astrophysics Data System (ADS)

    Musthak, Md.; Madhavi, M.; Ahsanullah, F. M.

    2017-08-01

    Carbon nanotubes (CNT's) are attracting scientific and industrial interest by virtue of their outstanding characteristics. The present research problem deals with the fabrication and characterization of E-glass fiber composites enhanced by carbon nanotubes. In the present study, three factors with two levels are considered. Hence, the design is called 23 full factorial design of experiment. The process parameters considered for the present problem are weight of multi-walled carbon nanotubes, process to disperse nano-particles in resin, and orientation of woven fabric. In addition, their levels considered for the experiment are higher level (+1) and lower level (-1). Fabrication of E-glass fiber composites was carried out according to design, and the specimens were prepared with respect to the ASTM standards D3039-76 and tensile testing was performed. The results show that the nano-particulated composite plate can be manufactured by considering lower level nano-particles stirred with probe sonicator and plied-up with hybrid orientation.

  17. Synthesis and evaluation of multi-wall carbon nanotube-paclitaxel complex as an anti-cancer agent.

    PubMed

    Ghasemvand, Fariba; Biazar, Esmaeil; Tavakolifard, Sara; Khaledian, Mohammad; Rahmanzadeh, Saeid; Momenzadeh, Daruosh; Afroosheh, Roshanak; Zarkalami, Faezeh; Shabannezhad, Marjan; Hesami Tackallou, Saeed; Massoudi, Nilofar; Heidari Keshel, Saeed

    2016-01-01

    The aim of this study was to design multi-walled carbon nanotubes (MWCNTs) loaded with paclitaxel (PTX) anti-cancer drug and investigate its anti-cancerous efficacy of human gastric cancer. Carbon nanotubes (CNTs) represent a novel nano-materials applied in various fields such as drug delivery due to their unique chemical properties and high drug loading. In this study, multi-walled carbon nanotubes (MWCNTs) pre-functionalized covalently with a paclitaxel (PTX) as an anti-cancer drug and evaluated by different analyses including, scanning electron microscope (SEM), particle size analyzer and cellular analyses. A well conjugated of anti-cancer drug on the carbon nanotube surfaces was shown. This study demonstrates that the MWCN-PTX complex is a potentially useful system for delivery of anti-cancer drugs. The flow cytometry, CFU and MTT assay results have disclosed that MWCNT/PTXs might promote apoptosis in MKN-45 gastric adenocarcinoma cell line. According to results, our simple method can be designed a candidate material for chemotherapy. It has presented a few bio-related applications including, their successful use as a nano-carriers for drug transport.

  18. Growth of multiwalled-carbon nanotubes using vertically aligned carbon nanofibers as templates/scaffolds and improved field-emission properties

    NASA Astrophysics Data System (ADS)

    Cui, H.; Yang, X.; Baylor, L. R.; Lowndes, D. H.

    2005-01-01

    Multiwalled-carbon nanotubes (MWCNTs) are grown on top of vertically aligned carbon nanofibers (VACNFs) via microwave plasma-enhanced chemical vapor deposition (MPECVD). The VACNFs are first grown in a direct-current plasma-enhanced chemical vapor deposition reactor using nickel catalyst. A layer of carbon-silicon materials is then deposited on the VACNFs and the nickel catalyst particle is broken down into smaller nanoparticles during an intermediate reactive-ion-plasma deposition step. These nickel nanoparticles nucleate and grow MWCNTs in the following MPECVD process. Movable-probe measurements show that the MWCNTs have greatly improved field-emission properties relative to the VACNFs.

  19. Comparative analysis of single-walled and multi-walled carbon nanotubes for electrochemical sensing of glucose on gold printed circuit boards.

    PubMed

    Alhans, Ruby; Singh, Anukriti; Singhal, Chaitali; Narang, Jagriti; Wadhwa, Shikha; Mathur, Ashish

    2018-09-01

    In the present work, a comparative study was performed between single-walled carbon nanotubes and multi-walled carbon nanotubes coated gold printed circuit board electrodes for glucose detection. Various characterization techniques were demonstrated in order to compare the modified electrodes viz. cyclic voltammetry, electrochemical impedance spectroscopy and chrono-amperometry. Results revealed that single-walled carbon nanotubes outperformed multi-walled carbon nanotubes and proved to be a better sensing interface for glucose detection. The single-walled carbon nanotubes coated gold printed circuit board electrodes showed a wide linear sensing range (1 mM to 100 mM) with detection limit of 0.1 mM with response time of 5 s while multi-walled carbon nanotubes coated printed circuit board gold electrodes showed linear sensing range (1 mM to 100 mM) with detection limit of 0.1 mM with response time of 5 s. This work provided low cost sensors with enhanced sensitivity, fast response time and reliable results for glucose detection which increased the affordability of such tests in remote areas. In addition, the comparative results confirmed that single-walled carbon nanotubes modified electrodes can be exploited for better amplification signal as compared to multi-walled carbon nanotubes. Copyright © 2018. Published by Elsevier B.V.

  20. Selective electrochemical reduction of CO2 to CO with a cobalt chlorin complex adsorbed on multi-walled carbon nanotubes in water.

    PubMed

    Aoi, Shoko; Mase, Kentaro; Ohkubo, Kei; Fukuzumi, Shunichi

    2015-06-25

    Electrocatalytic reduction of CO2 occurred efficiently using a glassy carbon electrode modified with a cobalt(II) chlorin complex adsorbed on multi-walled carbon nanotubes at an applied potential of -1.1 V vs. NHE to yield CO with a Faradaic efficiency of 89% with hydrogen production accounting for the remaining 11% at pH 4.6.

  1. Comprehensive studies on the nature of interaction between carboxylated multi-walled carbon nanotubes and bovine serum albumin.

    PubMed

    Lou, Kai; Zhu, Zhaohua; Zhang, Hongmei; Wang, Yanqing; Wang, Xiaojiong; Cao, Jian

    2016-01-05

    Herein, the interaction between carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) and bovine serum albumin has been investigated by using circular dichroism, UV-vis, and fluorescence spectroscopic methods and molecular modeling in order to better understand the basic behavior of carbon nanotubes in biological systems. The spectral results showed that MWCNTs-COOH bound to BSA and induced the relatively large changes in secondary structure of protein by mainly hydrophobic forces and π-π stacking interactions. Thermal denaturation of BSA in the presence of MWCNTs-COOH indicated that carbon nanotubes acted as a structure destabilizer for BSA. In addition, the putative binding site of MWCNTs-COOH on BSA was near to domain II. With regard to human health, the present study could provide a better understanding of the biological properties, cytotocicity of surface modified carbon nanotubes. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  2. Uptake and cytotoxic effects of multi-walled carbon nanotubes in human bronchial epithelial cells

    SciTech Connect

    Hirano, Seishiro, E-mail: seishiro@nies.go.j; Fujitani, Yuji; Furuyama, Akiko

    Carbon nanotubes (CNT) are cytotoxic to several cell types. However, the mechanism of CNT toxicity has not been fully studied, and dosimetric analyses of CNT in the cell culture system are lacking. Here, we describe a novel, high throughput method to measure cellular uptake of CNT using turbimetry. BEAS-2B, a human bronchial epithelial cell line, was used to investigate cellular uptake, cytotoxicity, and inflammatory effects of multi-walled CNT (MWCNT). The cytotoxicity of MWCNT was higher than that of crocidolite asbestos in BEAS-2B cells. The IC{sub 50} of MWCNT was 12 {mu}g/ml, whereas that of asbestos (crocidolite) was 678 {mu}g/ml. Overmore » the course of 5 to 8 h, BEAS-2B cells took up 17-18% of the MWCNT when they were added to the culture medium at a concentration of 10 {mu}g/ml. BEAS-2B cells were exposed to 2, 5, or 10 {mu}g/ml of MWCNT, and total RNA was extracted for cytokine cDNA primer array assays. The culture supernatant was collected for cytokine antibody array assays. Cytokines IL-6 and IL-8 increased in a dose dependent manner at both the mRNA and protein levels. Migration inhibitory factor (MIF) also increased in the culture supernatant in response to MWCNT. A phosphokinase array study using lysates from BEAS-2B cells exposed to MWCNT indicated that phosphorylation of p38, ERK1, and HSP27 increased significantly in response to MWCNT. Results from a reporter gene assays using the NF-{kappa}B or AP-1 promoter linked to the luciferase gene in transiently transfected CHO-KI cells revealed that NF-{kappa}B was activated following MWCNT exposure, while AP-1 was not changed. Collectively, MWCNT activated NF-{kappa}B, enhanced phosphorylation of MAP kinase pathway components, and increased production of proinflammatory cytokines in human bronchial epithelial cells.« less

  3. Bioaccumulation of Multiwall Carbon Nanotubes in Tetrahymena thermophila by Direct Feeding or Trophic Transfer

    DOE PAGES

    Mortimer, Monika; Petersen, Elijah J.; Buchholz, Bruce A.; ...

    2016-07-11

    We report that consumer goods contain multiwall carbon nanotubes (MWCNTs) that could be released during product life cycles into the environment, where their effects are uncertain. Here, we assessed MWCNT bioaccumulation in the protozoan Tetrahymena thermophila via trophic transfer from bacterial prey (Pseudomonas aeruginosa) versus direct uptake from growth media. The experiments were conducted using 14C-labeled MWCNT ( 14C-MWCNT) doses at or below 1 mg/L, which proved subtoxic since there were no adverse effects on the growth of the test organisms. A novel contribution of this study was the demonstration of the ability to quantify MWCNT bioaccumulation at low (submore » μg/kg) concentrations accomplished by employing accelerator mass spectrometry (AMS). After the treatments with MWCNTs at nominal concentrations of 0.01 mg/L and 1 mg/L, P. aeruginosa adsorbed considerable amounts of MWCNTs: (0.18 ± 0.04) μg/mg and (21.9 ± 4.2) μg/mg bacterial dry mass, respectively. At the administered MWCNT dose of 0.3 mg/L, T. thermophila accumulated up to (0.86 ± 0.3) μg/mg and (3.4 ± 1.1) μg/mg dry mass by trophic transfer and direct uptake, respectively.Finally, aAlthough MWCNTs did not biomagnify in the microbial food chain, MWCNTs bioaccumulated in the protozoan populations regardless of the feeding regime, which could make MWCNTs bioavailable for organisms at higher trophic levels.« less

  4. The pulmonary inflammatory response to multiwalled carbon nanotubes is influenced by gender and glutathione synthesis.

    PubMed

    Cartwright, Megan M; Schmuck, Stefanie C; Corredor, Charlie; Wang, Bingbing; Scoville, David K; Chisholm, Claire R; Wilkerson, Hui-Wen; Afsharinejad, Zahra; Bammler, Theodor K; Posner, Jonathan D; Shutthanandan, Vaithiyalingam; Baer, Donald R; Mitra, Somenath; Altemeier, William A; Kavanagh, Terrance J

    2016-10-01

    Inhalation of multiwalled carbon nanotubes (MWCNTs) during their manufacture or incorporation into various commercial products may cause lung inflammation, fibrosis, and oxidative stress in exposed workers. Some workers may be more susceptible to these effects because of differences in their ability to synthesize the major antioxidant and immune system modulator glutathione (GSH). Accordingly, in this study we examined the influence of GSH synthesis and gender on MWCNT-induced lung inflammation in C57BL/6 mice. GSH synthesis was impaired through genetic manipulation of Gclm, the modifier subunit of glutamate cysteine ligase, the rate-limiting enzyme in GSH synthesis. Twenty-four hours after aspirating 25µg of MWCNTs, all male mice developed neutrophilia in their lungs, regardless of Gclm genotype. However, female mice with moderate (Gclm heterozygous) and severe (Gclm null) GSH deficiencies developed significantly less neutrophilia. We found no indications of MWCNT-induced oxidative stress as reflected in the GSH content of lung tissue and epithelial lining fluid, 3-nitrotyrosine formation, or altered mRNA or protein expression of several redox-responsive enzymes. Our results indicate that GSH-deficient female mice are rendered uniquely susceptible to an attenuated neutrophil response. If the same effects occur in humans, GSH-deficient women manufacturing MWCNTs may be at greater risk for impaired neutrophil-dependent clearance of MWCNTs from the lung. In contrast, men may have effective neutrophil-dependent clearance, but may be at risk for lung neutrophilia regardless of their GSH levels. Copyright © 2016. Published by Elsevier B.V.

  5. Effects of multi-walled carbon nanotubes on a murine allergic airway inflammation model

    SciTech Connect

    Inoue, Ken-ichiro; Koike, Eiko; Yanagisawa, Rie

    The development of nanotechnology has increased the risk of exposure to types of particles other than combustion-derived particles in the environment, namely, industrial nanomaterials. On the other hand, patients with bronchial asthma are sensitive to inhaled substances including particulate matters. This study examined the effects of pulmonary exposure to a type of nano-sized carbon nanotube (multi-walled nanotubes: MWCNT) on allergic airway inflammation in vivo and their cellular mechanisms in vitro. In vivo, ICR mice were divided into 4 experimental groups. Vehicle, MWCNT (50 {mu}g/animal), ovalbumin (OVA), and OVA + MWCNT were repeatedly administered intratracheally. Bronchoalveolar lavage (BAL) cellularity, lung histology,more » levels of cytokines related to allergic inflammation in lung homogenates/BAL fluids (BALFs), and serum immunoglobulin levels were studied. Also, we evaluated the impact of MWCNT (0.1-1 {mu}g/ml) on the phenotype and function of bone marrow-derived dendritic cells (DC) in vitro. MWCNT aggravated allergen-induced airway inflammation characterized by the infiltration of eosinophils, neutrophils, and mononuclear cells in the lung, and an increase in the number of goblet cells in the bronchial epithelium. MWCNT with allergen amplified lung protein levels of Th cytokines and chemokines compared with allergen alone. MWCNT exhibited adjuvant activity for allergen-specific IgG{sub 1} and IgE. MWCNT significantly increased allergen (OVA)-specific syngeneic T-cell proliferation, particularly at a lower concentration in vitro. Taken together, MWCNT can exacerbate murine allergic airway inflammation, at least partly, via the promotion of a Th-dominant milieu. In addition, the exacerbation may be partly through the inappropriate activation of antigen-presenting cells including DC.« less

  6. The pulmonary inflammatory response to multiwalled carbon nanotubes is influenced by gender and glutathione synthesis

    SciTech Connect

    Cartwright, Megan M.; Schmuck, Stefanie C.; Corredor, Charlie

    Here, inhalation of multiwalled carbon nanotubes (MWCNTs) during their manufacture or incorporation into various commercial products may cause lung inflammation, fibrosis, and oxidative stress in exposed workers. Some workers may be more susceptible to these effects because of differences in their ability to synthesize the major antioxidant and immune system modulator glutathione (GSH). Accordingly, in this study we examined the influence of GSH synthesis and gender on MWCNT-induced lung inflammation in C57BL/6 mice. GSH synthesis was impaired through genetic manipulation of Gclm, the modifier subunit of glutamate cysteine ligase, the rate-limiting enzyme in GSH synthesis. Twenty-four hours after aspirating 25more » µg of MWCNTs, all male mice developed neutrophilia in their lungs, regardless of Gclm genotype. However, female mice with moderate ( Gclm heterozygous) and severe ( Gclm null) GSH deficiencies developed significantly less neutrophilia. We found no indications of MWCNT-induced oxidative stress as reflected in the GSH content of lung tissue and epithelial lining fluid, 3-nitrotyrosine formation, or altered mRNA or protein expression of several redox-responsive enzymes. Our results indicate that GSH-deficient female mice are rendered uniquely susceptible to an attenuated neutrophil response. If the same effects occur in humans, GSH-deficient women manufacturing MWCNTs may be at greater risk for impaired neutrophil-dependent clearance of MWCNTs from the lung. In contrast, men may have effective neutrophil-dependent clearance, but may be at risk for lung neutrophilia regardless of their GSH levels.« less

  7. Predicting pulmonary fibrosis in humans after exposure to multi-walled carbon nanotubes (MWCNTs).

    PubMed

    Sharma, Monita; Nikota, Jake; Halappanavar, Sabina; Castranova, Vincent; Rothen-Rutishauser, Barbara; Clippinger, Amy J

    2016-07-01

    The increased production and use of multi-walled carbon nanotubes (MWCNTs) in a diverse array of consumer, medical, and industrial applications have raised concerns about potential human exposure to these materials in the workplace and ambient environments. Inhalation is a primary route of exposure to MWCNTs, and the existing data indicate that they are potentially hazardous to human health. While a 90-day rodent inhalation test (e.g., OECD Test No. 413: subchronic inhalation toxicity: 90-day study or EPA Health Effects Test Guidelines OPPTS 870.3465 90-day inhalation toxicity) is recommended by the U.S. Environmental Protection Agency Office of Pollution Prevention and Toxics for MWCNTs (and other CNTs) if they are to be commercially produced (Godwin et al. in ACS Nano 9:3409-3417, 2015), this test is time and cost-intensive and subject to scientific and ethical concerns. As a result, there has been much interest in transitioning away from studies on animals and moving toward human-based in vitro and in silico models. However, given the multiple mechanisms of toxicity associated with subchronic exposure to inhaled MWCNTs, a battery of non-animal tests will likely be needed to evaluate the key endpoints assessed by the 90-day rodent study. Pulmonary fibrosis is an important adverse outcome related to inhalation exposure to MWCNTs and one that the non-animal approach should be able to assess. This review summarizes the state-of-the-science regarding in vivo and in vitro toxicological methods for predicting MWCNT-induced pulmonary fibrosis.

  8. Multi-walled carbon nanotubes injure the plasma membrane of macrophages

    SciTech Connect

    Hirano, Seishiro; Kanno, Sanae; Furuyama, Akiko

    2008-10-15

    Carbon nanotubes (CNTs) are emerging nanotechnology materials which are likely to be mass-produced in the near future. However, prior to mass-production, certain health-related concerns should first be addressed. For example, when inhaled, the thin-fibrous shape and the biopersistent characteristics of CNTs may cause pulmonary diseases, in a manner similar to asbestos. In the present study, mouse macrophages (J774.1) were exposed to highly-purified multi-walled CNTs (MWCNTs, 67 nm) or to UICC crocidolite in order to evaluate the toxicity of these nano-size fibers. The cytotoxicity of MWCNTs was found to be higher than that of crocidolite. The toxic effect of MWCNTs wasmore » not affected by N-acetylcysteine, an antioxidant, or buthionine sulfoximine, a glutathione synthesis inhibitor. cDNA microarray analyses suggested that the cytotoxicity of MWCNTs could not be explained satisfactorily by either an increase or decrease of gene expression, although mRNA levels of some cytokines were slightly increased by MWCNTs. Moreover, MWCNTs did not significantly activate either MAP kinases such as ERK, JNK and p38, nor common apoptosis pathways such as caspase 3 and PARP. Electron microscopic studies indicated that MWCNTs associate with the plasma membrane of macrophages and disrupt the integrity of the membrane. Several proteins were found to adsorb onto MWCNTs when MWCNT-exposed macrophages were gently lysed. One of these proteins was macrophage receptor with collagenous structure (MARCO). MARCO-transfected CHO-K1 cells associated with MWCNTs more rapidly than mock-transfected cells. These results indicate that MWCNTs probably trigger cytotoxic effects in phagocytotic cells by reacting with MARCO on the plasma membrane and rupturing the plasma membrane.« less

  9. The pulmonary inflammatory response to multiwalled carbon nanotubes is influenced by gender and glutathione synthesis

    DOE PAGES

    Cartwright, Megan M.; Schmuck, Stefanie C.; Corredor, Charlie; ...

    2016-08-21

    Here, inhalation of multiwalled carbon nanotubes (MWCNTs) during their manufacture or incorporation into various commercial products may cause lung inflammation, fibrosis, and oxidative stress in exposed workers. Some workers may be more susceptible to these effects because of differences in their ability to synthesize the major antioxidant and immune system modulator glutathione (GSH). Accordingly, in this study we examined the influence of GSH synthesis and gender on MWCNT-induced lung inflammation in C57BL/6 mice. GSH synthesis was impaired through genetic manipulation of Gclm, the modifier subunit of glutamate cysteine ligase, the rate-limiting enzyme in GSH synthesis. Twenty-four hours after aspirating 25more » µg of MWCNTs, all male mice developed neutrophilia in their lungs, regardless of Gclm genotype. However, female mice with moderate ( Gclm heterozygous) and severe ( Gclm null) GSH deficiencies developed significantly less neutrophilia. We found no indications of MWCNT-induced oxidative stress as reflected in the GSH content of lung tissue and epithelial lining fluid, 3-nitrotyrosine formation, or altered mRNA or protein expression of several redox-responsive enzymes. Our results indicate that GSH-deficient female mice are rendered uniquely susceptible to an attenuated neutrophil response. If the same effects occur in humans, GSH-deficient women manufacturing MWCNTs may be at greater risk for impaired neutrophil-dependent clearance of MWCNTs from the lung. In contrast, men may have effective neutrophil-dependent clearance, but may be at risk for lung neutrophilia regardless of their GSH levels.« less

  10. Multiwalled carbon nanotubes for stray light suppression in space flight instruments

    NASA Astrophysics Data System (ADS)

    Hagopian, John G.; Getty, Stephanie A.; Quijada, Manuel; Tveekrem, June; Shiri, Ron; Roman, Patrick; Butler, James; Georgiev, Georgi; Livas, Jeff; Hunt, Cleophus; Maldonado, Alejandro; Talapatra, Saikat; Zhang, Xianfeng; Papadakis, Stergios J.; Monica, Andrew H.; Deglau, David

    2010-08-01

    Observations of the Earth are extremely challenging; its large angular extent floods scientific instruments with high flux within and adjacent to the desired field of view. This bright light diffracts from instrument structures, rattles around and invariably contaminates measurements. Astrophysical observations also are impacted by stray light that obscures very dim objects and degrades signal to noise in spectroscopic measurements. Stray light is controlled by utilizing low reflectance structural surface treatments and by using baffles and stops to limit this background noise. In 2007 GSFC researchers discovered that Multiwalled Carbon Nanotubes (MWCNTs) are exceptionally good absorbers, with potential to provide order-of-magnitude improvement over current surface treatments and a resulting factor of 10,000 reduction in stray light when applied to an entire optical train. Development of this technology will provide numerous benefits including: a.) simplification of instrument stray light controls to achieve equivalent performance, b.) increasing observational efficiencies by recovering currently unusable scenes in high contrast regions, and c.) enabling low-noise observations that are beyond current capabilities. Our objective was to develop and apply MWCNTs to instrument components to realize these benefits. We have addressed the technical challenges to advance the technology by tuning the MWCNT geometry using a variety of methods to provide a factor of 10 improvement over current surface treatments used in space flight hardware. Techniques are being developed to apply the optimized geometry to typical instrument components such as spiders, baffles and tubes. Application of the nanostructures to alternate materials (or by contact transfer) is also being investigated. In addition, candidate geometries have been tested and optimized for robustness to survive integration, testing, launch and operations associated with space flight hardware. The benefits of this

  11. Sodium chloride-catalyzed oxidation of multiwalled carbon nanotubes for environmental benefit.

    PubMed

    Endo, Morinobu; Takeuchi, Kenji; Tajiri, Takeyuki; Park, Ki Chul; Wang, Feng; Kim, Yoong-Ahm; Hayashi, Takuya; Terrones, Mauricio; Dresselhaus, Mildred S

    2006-06-22

    A sodium chloride (NaCl) catalyst (0.1 w/w %) lowers the oxidation temperature of graphitized multiwalled carbon nanotubes: MWCNT-20 (diameter: 20-70 nm) and MWCNT-80 (diameter: 80-150 nm). The analysis of the reaction kinetics indicates that the oxidation of MWCNT-20 and MWCNT-80 mixed with no NaCl exhibits single reaction processes with activation energies of E(a) = 159 and 152 kJ mol(-1), respectively. The oxidation reaction in the presence of NaCl is shown to consist of two different reaction processes, that is, a first reaction and a second reaction process. The first reaction process is dominant at a low temperature of around 600 degrees C, while the second reaction process becomes more dominant than the first one in a higher temperature region. The activation energies of the first reaction processes (MWCNT-20: E(a1) = 35.7 kJ mol(-1); MWCNT-80: E(a1) = 43.5 kJ mol(-1)) are much smaller than those of the second reaction processes (MWCNT-20: E(a2) = 170 kJ mol(-1); MWCNT-80: E(a2) = 171 kJ mol(-1)). The comparison of the kinetic parameters and the results of the spectroscopic and microscopic analyses imply that the lowering of the oxidation temperature in the presence of NaCl results from the introduction of disorder into the graphitized MWCNTs (during the first reaction process), thus increasing the facility of the oxidation reaction of the disorder-induced nanotubes (in the second reaction process). It is found that the larger nanopits and cracks on the outer graphitic layers are caused by the catalytic effect of NaCl. Therefore, the NaCl-mixed samples showed more rapid and stronger oxidation compared with that of the nonmixed samples at the same residual quantity.

  12. Quasi-QSAR for mutagenic potential of multi-walled carbon-nanotubes.

    PubMed

    Toropov, Andrey A; Toropova, Alla P

    2015-04-01

    Available on the Internet, the CORAL software (http://www.insilico.eu/coral) has been used to build up quasi-quantitative structure-activity relationships (quasi-QSAR) for prediction of mutagenic potential of multi-walled carbon-nanotubes (MWCNTs). In contrast with the previous models built up by CORAL which were based on representation of the molecular structure by simplified molecular input-line entry system (SMILES) the quasi-QSARs based on the representation of conditions (not on the molecular structure) such as concentration, presence (absence) S9 mix, the using (or without the using) of preincubation were encoded by so-called quasi-SMILES. The statistical characteristics of these models (quasi-QSARs) for three random splits into the visible training set and test set and invisible validation set are the following: (i) split 1: n=13, r(2)=0.8037, q(2)=0.7260, s=0.033, F=45 (training set); n=5, r(2)=0.9102, s=0.071 (test set); n=6, r(2)=0.7627, s=0.044 (validation set); (ii) split 2: n=13, r(2)=0.6446, q(2)=0.4733, s=0.045, F=20 (training set); n=5, r(2)=0.6785, s=0.054 (test set); n=6, r(2)=0.9593, s=0.032 (validation set); and (iii) n=14, r(2)=0.8087, q(2)=0.6975, s=0.026, F=51 (training set); n=5, r(2)=0.9453, s=0.074 (test set); n=5, r(2)=0.8951, s=0.052 (validation set). Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Properties of a weakly ionized NO gas sensor based on multi-walled carbon nanotubes

    SciTech Connect

    Zhang, Jingyuan; Zhang, Yong, E-mail: zhyong@mail.xjtu.edu.cn; Pan, Zhigang

    2015-08-31

    Nitric oxide NO is one of the major targets for environmental monitoring, but the existing NO sensors are limited by their low sensitivity and narrow test range. Here, a NO gas sensor employing multiwalled carbon nanotubes (MWCNTs) was fabricated, and its properties in NO–N{sub 2} mixture were investigated from both emission and ionization. The current I{sub e} passing through the nanotubes cathode was found to decrease with increasing NO concentration and increase linearly in different slopes with the extracting voltage U{sub e}. It is shown that the Schottky barrier of the MWCNTs calculated by I{sub e} increased with NO concentrationmore » due to the adsorption of NO gas, which restrained the electron emission and consequently weakened the ionization. The positive ion currents I{sub c} passing through the collecting electrode at different voltages of U{sub e} were found to monotonically decrease with increasing NO concentration, which was induced by both of the reduced electron emission and the consumption of the two excited metastable states N{sub 2}(A{sup 3}∑{sub u}{sup +}) and N{sub 2}(a′{sup 1}∑{sub u}{sup −}) by NO. The sensor exhibited high sensitivity at the low temperature of 30 °C. The calculated conductivity was found to be able to take place of I{sub c} for NO detection in a wide voltage range of 80–150 V U{sub e}.« less

  14. Changes in DNA methylation induced by multi-walled carbon nanotube exposure in the workplace.

    PubMed

    Ghosh, Manosij; Öner, Deniz; Poels, Katrien; Tabish, Ali M; Vlaanderen, Jelle; Pronk, Anjoeka; Kuijpers, Eelco; Lan, Qing; Vermeulen, Roel; Bekaert, Bram; Hoet, Peter Hm; Godderis, Lode

    This study was designed to assess the epigenetic alterations in blood cells, induced by occupational exposure to multi-wall carbon nanotubes (MWCNT). The study population comprised of MWCNT-exposed workers (n=24) and unexposed controls (n=43) from the same workplace. We measured global DNA methylation/hydroxymethylation levels on the 5th cytosine residues using a validated liquid chromatography tandem-mass spectrometry (LC-MS/MS) method. Sequence-specific methylation of LINE1 retrotransposable element 1 (L1RE1) elements, and promoter regions of functionally important genes associated with epigenetic regulation [DNA methyltransferase-1 (DNMT1) and histone deacetylase 4 (HDAC4)], DNA damage/repair and cell cycle pathways [nuclear protein, coactivator of histone transcription/ATM serine/threonine kinase (NPAT/ATM)], and a potential transforming growth factor beta (TGF-β) repressor [SKI proto-oncogene (SKI)] were studied using bisulfite pyrosequencing. Analysis of global DNA methylation levels and hydroxymethylation did not reveal significant difference between the MWCNT-exposed and control groups. No significant changes in Cytosine-phosphate-Guanine (CpG) site methylation were observed for the LINE1 (L1RE1) elements. Further analysis of gene-specific DNA methylation showed a significant change in methylation for DNMT1, ATM, SKI, and HDAC4 promoter CpGs in MWCNT-exposed workers. Since DNA methylation plays an important role in silencing/regulation of the genes, and many of these genes have been associated with occupational and smoking-induced diseases and cancer (risk), aberrant methylation of these genes might have a potential effect in MWCNT-exposed workers.

  15. Functional characteristics, wettability properties and cytotoxic effect of starch film incorporated with multi-walled and hydroxylated multi-walled carbon nanotubes.

    PubMed

    Shahbazi, Mahdiyar; Rajabzadeh, Ghadir; Sotoodeh, Shahnaz

    2017-11-01

    Two types of multi-walled carbon nanotubes (CNT and CNT-OH) at different levels (0.1-0.9wt%) were introduced into starch matrix in order to modify its functional properties. The optimum concentration of each nanotube was selected based on the results of water solubility, water permeability and mechanical experiments. The physico-mechanical data showed that CNT up to 0.7wt% led to a notable increase in water resistance, water barrier property and tensile strength, whilst regarding CNT-OH, these improvements found at 0.9wt%. Therefore, effects of optimized level of each nanotube on the starch film were evaluated by XRD, surface hydrophobicity, wettability and surface energy tests. XRD revealed that the position of starch characteristic peak shifted to higher degree after nanotubes introducing. The hydrophobic character of the film was greatly increased with incorporation of nanoparticles, as evidenced by increased contact angle with greatest value regarding CNT-OH. Moreover, CNT-OH notably decreased the surface free energy of the starch film. Finally, the conformity of both nanocomposites with actual food regulations on biodegradable materials was tested by cytotoxicity assay to evaluate the possibility of application in food packaging sector. Both nanocomposite films had potential of cytotoxic effects, since they could increase cytoplasmic lactate dehydrogenase release from L-929 fibroblast cells in contact with their surface. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Application of Polypyrrole Multi-Walled Carbon Nanotube Composite Layer for Detection of Mercury, Lead and Iron Ions Using Surface Plasmon Resonance Technique

    PubMed Central

    Sadrolhosseini, Amir Reza; Noor, A. S. M.; Bahrami, Afarin; Lim, H. N.; Talib, Zainal Abidin; Mahdi, Mohd. Adzir

    2014-01-01

    Polypyrrole multi-walled carbon nanotube composite layers were used to modify the gold layer to measure heavy metal ions using the surface plasmon resonance technique. The new sensor was fabricated to detect trace amounts of mercury (Hg), lead (Pb), and iron (Fe) ions. In the present research, the sensitivity of a polypyrrole multi-walled carbon nanotube composite layer and a polypyrrole layer were compared. The application of polypyrrole multi-walled carbon nanotubes enhanced the sensitivity and accuracy of the sensor for detecting ions in an aqueous solution due to the binding of mercury, lead, and iron ions to the sensing layer. The Hg ion bonded to the sensing layer more strongly than did the Pb and Fe ions. The limitation of the sensor was calculated to be about 0.1 ppm, which produced an angle shift in the region of 0.3° to 0.6°. PMID:24733263

  17. One step biofunctionalized electrospun multiwalled carbon nanotubes embedded zinc oxide nanowire interface for highly sensitive detection of carcinoma antigen-125.

    PubMed

    Paul, K Brince; Singh, Vikrant; Vanjari, Siva Rama Krishna; Singh, Shiv Govind

    2017-02-15

    Ovarian cancer is the most leading cause of cancer-related death in women . The carcinoma antigen-125, which is found on the surface of many ovarian cancer cells is known to be a gold standard clinical biomarker associated with life-threatening gynecological malignancy. In this work, we demonstrate a novel biosensor platform based on multiwalled carbon nanotubes embedded zinc oxide nanowire for the ultrasensitive detection of carcinoma antigen-125. Label free detection of the carcinoma antigen-125 was accomplished by differential voltammetry technique that demonstrated excellent sensitivity (90.14µA/(U/mL)/cm 2 ) with a detection limit of 0.00113UmL -1 concentration. The fabricated immunosensor exhibits good performance with wider detection range (0.001UmL -1 -1kUmL -1 ), reproducibility, selectivity, acceptable stability, and thus is a potential cost-effective methodology for point-of-care diagnosis. The multiwalled carbon nanotubes (MWCNTs) embedded highly oriented zinc oxide (ZnO) nanowires were synthesized by simple, low cost electrospinning technique. Compared to pure ZnO nanowires, electrochemical activity of MWCNTs embedded ZnO nanowires was found to be much higher. The calcination temperature was optimized to avoid any decomposition of the CNTs and to obtain multiwalled carbon nanotubes embedded highly crystalline ZnO nanowires. The salient feature of this biosensing platform is that one step calcination process is enough to create the functional groups on MWCNT-ZnO nanowire surface that are effective for the covalent conjugation of antibody without further surface modification. To the best of our knowledge, this is the first report on MWCNT-ZnO nanowire based immunosensor explored for the detection of cancer biomarker. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. One-Step Pyrolytic Synthesis of Multiwalled Carbon Nanotubes: The Role of Resupply of Carbon Species on the Quality Control.

    PubMed

    Rajavel, Krishnamoorthy; Saravanan, Padmanapan; Kumar, Ramasamy Thangavelu Rajendra

    2018-05-01

    An investigation on varying experimental parameters such as solution quantity (2.5, 5 and 7.5 mL) and reaction time (15, 30, 45 and 60 min) was carried out for the production of high-quality multiwalled carbon nanotubes (MWCNTs) in one step pyrolysis. Structural analysis revealed the uniform diameter distribution and the length of nanotubes in the range of 60-80 nm and 0.4-2 μm, respectively. Raman and X-ray diffraction analysis showed a remarkable reduction in defect density with increase in graphitization degree, upon increasing the solution volume and reaction time. MWCNTs prepared at higher solution quantity (7.5 mL) with higher reaction time (60 min) showed higher crystallinity (70% graphitization) and lower defect density (ID/IG: 0.56). The attainment in equilibrium of evaporation cum precipitation in formation of high quality nanotubes structure is evaluated. An effective resupplying of condensed precursors by re-evaporation leads for the achievement of low defect density nanotubes with higher product yield is achieved.

  19. PH-sensitive dispersion of carbon nanotubes by myoglobin

    NASA Astrophysics Data System (ADS)

    Nie, Haiyu; Shen, Ganni; Sun, Junlin; Zhang, Tao

    2017-03-01

    A facile and effective method of dispersion of double-walled carbon nanotubes (DWNTs) was developed. At appropriate pH value and sonication, myoglobin helps the solubilization of DWNTs. The product is a pH-sensitive dispersion, which remains in a highly dispersed state at pH<3.0 and pH>10.0. This approach can be used to disperse DWNTs in scale. A reversible conversion of the highly dispersed state to the aggregated state could be observed by changing the pH value. This feature holds great promise for the development of pH sensors.

  20. The effect of different temperature profiles upon the length and crystallinity of vertically-aligned multi-walled carbon nanotubes.

    PubMed

    Yun, Jongju; Lee, Cheesung; Zheng, Qing; Baik, Seunghyun

    2012-08-01

    We synthesized vertically-aligned multi-walled carbon nanotubes with an inner diameter of 1.6-7.5 nm and stack height of 80-28600 microm by chemical vapor deposition. The effects of synthesis conditions such as substrate position in the tube furnace, maximum temperature, temperature increasing rate and synthesis duration on the structure of nanotubes were investigated. It was found that slightly faster temperature increase rate resulted in significantly longer length, larger diameter and more defects of nanotubes. Structural parameters such as inner, outer diameters, wall thickness and defects were investigated using transmission electron microscopy and Raman spectroscopy.

  1. Dielectric properties of vertically aligned multi-walled carbon nanotubes in the terahertz and mid-infrared range

    NASA Astrophysics Data System (ADS)

    Thomson, Mark D.; Zouaghi, Wissem; Meng, Fanqi; Wiecha, Matthias M.; Rabia, Kaneez; Heinlein, Thorsten; Hussein, Laith; Babu, Deepu; Yadav, Sandeep; Engstler, Jörg; Schneider, Jörg J.; Nicoloso, Norbert; Rychetský, Ivan; Kužel, Petr; Roskos, Hartmut G.

    2018-01-01

    We investigate the broadband dielectric properties of vertically aligned, multi-wall carbon nanotubes (VACNT), over both the terahertz (THz) and mid-infrared spectral ranges. The nominally undoped, metallic VACNT samples are probed at normal incidence, i.e. the response is predominantly due to polarisation perpendicular to the CNT axis. A detailed comparison of various conductivity models and previously reported results is presented for the non-Drude behaviour we observe in the conventional THz range (up to 2.5 THz). Extension to the mid-infrared range reveals an absorption peak at \

  2. Sensing of low concentration of ammonia at room temperature by cadmium sulphide nanoparticle decorated multiwalled carbon nanotube: fabrication and characterisation

    NASA Astrophysics Data System (ADS)

    Hasnahena, S. T.; Roy, M.

    2017-12-01

    A chemical approach to fabricate a CdS-attached multiwall carbon nanotube (CdS/MWCNT) based on NH3 gas sensor is presented. During chemical assemblage the formation of the chemical composition and chemical state of CdS/MWCNT, evaluated through XPS, is also enumerated in this work. Results on NH3 gas sensitivity at room temperature with theoretical interpretation make this work noticeable. The overall finding is that the CdS/MWCNT sensor senses NH3 at room temperature as low as 10 ppb concentration. The sensor shows good reproducibility and stability, construed on the performance of the sensor over a period of six months.

  3. Detection of Multi-walled Carbon Nanotubes and Carbon Nanodiscs on Workplace Surfaces at a Small-Scale Producer.

    PubMed

    Hedmer, Maria; Ludvigsson, Linus; Isaxon, Christina; Nilsson, Patrik T; Skaug, Vidar; Bohgard, Mats; Pagels, Joakim H; Messing, Maria E; Tinnerberg, Håkan

    2015-08-01

    The industrial use of novel-manufactured nanomaterials such as carbon nanotubes and carbon nanodiscs is increasing globally. Occupational exposure can occur during production, downstream use, and disposal. The health effects of many nanomaterials are not yet fully characterized and to handle nano-objects, their aggregates and agglomerates >100nm (NOAA), a high degree of control measures and personal protective equipment are required. The emission of airborne NOAA during production and handling can contaminate workplace surfaces with dust, which can be resuspended resulting in secondary inhalation exposures and dermal exposures. This study surveys the presence of carbon-based nanomaterials, such as multi-walled carbon nanotubes (MWCNTs) and carbon nanodiscs, as surface contamination at a small-scale producer using a novel tape sampling method. Eighteen different surfaces at a small-scale producer were sampled with an adhesive tape sampling method. The surfaces selected were associated with the production and handling of MWCNT powder in the near-field zone. Surfaces in the far-field zone were also sampled. In addition, tape stripping of the skin was performed on one worker. The tape samples were analysed with scanning electron microscopy to detect the carbon-based NOAA. Air sampling with a personal impactor was also performed on a worker who was producing MWCNTs the same day as the tape samples were collected. MWCNTs were detected in 50% of the collected tape samples and carbon nanodiscs in 17%. MWCNTs and carbon nanodiscs were identified in all parts of the workplace, thus, increasing the risk for secondary inhalation and dermal exposure of the workers. Both airborne MWCNTs and carbon nanodiscs were detected in the personal impactor samples. The tape-strip samples from the worker showed no presence of carbon-containing nanoparticles. Tape sampling is a functional method for detecting surface contamination of carbon-based NOAA and for exposure control during

  4. Electrochemical detection and degradation of ibuprofen from water on multi-walled carbon nanotubes-epoxy composite electrode.

    PubMed

    Motoc, Sorina; Remes, Adriana; Pop, Aniela; Manea, Florica; Schoonman, Joop

    2013-04-01

    This work describes the electrochemical behaviour of ibuprofen on two types of multi-walled carbon nanotubes based composite electrodes, i.e., multi-walled carbon nanotubes-epoxy (MWCNT) and silver-modified zeolite-multi-walled carbon nanotubes-epoxy (AgZMWCNT) composites electrodes. The composite electrodes were obtained using two-roll mill procedure. SEM images of surfaces of the composites revealed a homogeneous distribution of the composite components within the epoxy matrix. AgZMWCNT composite electrode exhibited the better electrical conductivity and larger electroactive surface area. The electrochemical determination of ibuprofen (IBP) was achieved using AgZMWCNT by cyclic voltammetry, differential-pulsed voltammetry, square-wave voltammetry and chronoamperometry. The IBP degradation occurred on both composite electrodes under controlled electrolysis at 1.2 and 1.75 V vs. Ag/AgCl, and IBP concentration was determined comparatively by differential-pulsed voltammetry, under optimized conditions using AgZMWCNT electrode and UV-Vis spectrophotometry methods to determine the IBP degradation performance for each electrode. AgZMWCNT electrode exhibited a dual character allowing a double application in IBP degradation process and its control.

  5. Immobilization of ruthenium phthalocyanine on silica-coated multi-wall partially oriented carbon nanotubes: Electrochemical detection of fenitrothion pesticide

    SciTech Connect

    Canevari, Thiago C., E-mail: tccanevari@gmail.com; Prado, Thiago M.; Cincotto, Fernando H.

    Highlights: • Hybrid material, SiO{sub 2}/MWCNTs containing ruthenium phthalocyanine (RuPc) synthesized in situ. • Silica containing multi-walled carbon nanotube partially oriented. • Determination of pesticide fenitrothion in orange juice. - Abstract: This paper reports on the determination of the pesticide fenitrothion using a glassy carbon electrode modified with silica-coated, multi-walled, partially oriented carbon nanotubes, SiO{sub 2}/MWCNTs, containing ruthenium phthalocyanine (RuPc) synthesized in situ. The hybrid SiO{sub 2}/MWCNTs/RuPc material was characterized by UV–vis absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and differential pulse voltammetry. The modified electrode showed well-defined peaks in the presencemore » of fenitrothion in acetate buffer, pH 4.5, with a sensitivity of 0.0822 μA μM{sup −1} mm{sup −2} and a detection limit of 0.45 ppm. Notably, the modified SiO{sub 2}/MWCNTs/RuPc electrodes with did not suffer from significant influences in the presence of other organophosphorus pesticides during the determination of the fenitrothion pesticide. Moreover, this modified electrode showed excellent performance in the determination of fenitrothion in orange juice.« less

  6. Improved mechanical and electrical properties in electrospun polyimide/multiwalled carbon nanotubes nanofibrous composites

    SciTech Connect

    Zha, Jun-Wei; Sun, Fang; Wang, Si-Jiao

    2014-10-07

    Highly aligned polyimide (PI) and PI/multi-walled carbon nanotubes (PI/MWCNTs) nanofibrous composites by incorporating poly(ethylene oxide) as the dispersing medium were fabricated using electrospinning technique. The morphology, mechanical, and electrical properties of the electrospun nanofibrous composites were investigated. Scanning electron microscope showed that the functionalized MWCNTs (f-MWCNTs) were well dispersed and oriented along the nanofiber axis. Analysis of electrical properties indicated a remarkable improvement on the alternating current conductivity by introduction of the aligned f-MWCNTs. Besides, with addition of 3 vol. % f-MWCNTs, the obvious enhancement of tensile modulus and strength was achieved. Thus, the electrospun PI/MWCNTs nanofibrous composites have greatmore » potential applications in multifunctional engineering materials.« less

  7. Composites of multi-walled carbon nanotubes with polypropylene and thermoplastic olefin blends prepared by melt compounding

    NASA Astrophysics Data System (ADS)

    Petrie, Kyle G.

    Composites of multi-walled carbon nanotubes (MWCNTs) with polypropylene (PP) and thermoplastic olefins (TPOs) were prepared by melt compounding. Two non-covalent functionalization methods were employed to improve nanotube dispersion and the resulting composite properties are reported. The first functionalization approach involved partial coating of the surface of the nanotubes with a hyperbranched polyethylene (HBPE). MWCNT functionalization with HBPE was only moderately successful in breaking up the large aggregates that formed upon melt mixing with PP. In spite of the formation of large aggregates, the samples were conductive above a percolation threshold of 7.3 wt%. MWCNT functionalization did not disrupt the electrical conductivity of the nanotubes. The composite strength was improved with addition of nanotubes, but ductility was severely compromised because of the existence of aggregates. The second method involved PP matrix functionalization with aromatic moieties capable of pi-pi interaction with MWCNT sidewalls. Various microscopy techniques revealed the addition of only 25 wt% of PP-g-pyridine (Py) to the neat PP was capable of drastically reducing nanotube aggregate size and amount. Raman spectroscopy confirmed improved polymer/nanotube interaction with the PP-g-Py matrix. Electrical percolation threshold was obtained at a MWCNT loading of approximately 1.2 wt%. Electrical conductivity on the order of 10 -2 S/m was achieved, suggesting possible use in semi-conducting applications. Composite strength was improved upon addition of MWCNTs. The matrix functionalization with Py resulted in a significant improvement in composite ductility when filled with MWCNTs in comparison to its maleic anhydride (MA) counterpart. Preliminary investigations suggest that the use of alternating current (AC) electric fields may be effective in aligning nanotubes in PP to reduce the filler loading required for electrical percolation. Composites containing MWCNT within PP

  8. Amorphous Transition Metal Sulfides Anchored on Amorphous Carbon-Coated Multiwalled Carbon Nanotubes for Enhanced Lithium-Ion Storage.

    PubMed

    Jin, Rencheng; Zhai, Qinghe; Wang, Qingyao

    2017-10-09

    Cobalt sulfide and molybdenum sulfide, with high theoretical capacities, have been considered as one of most promising anode materials for lithium-ion batteries (LIBs). However, the poor cyclability and low rate performances originating from the large volume expansion and poor electrical conductivity extremely inhibit their practical application. Here, the electrochemical performances are effectively improved by growing amorphous cobalt sulfide and molybdenum sulfide onto amorphous carbon-coated multiwalled carbon nanotubes (CNTs@C@CoS 2 and CNTs@C@MoS 2 ). The CNTs@C@CoS 2 presents a high reversible specific capacity of 1252 mAh g -1 at 0.2 Ag -1 , excellent rate performance of 672 mAh g -1 (5 Ag -1 ), and enhanced cycle life of 598 mAh g -1 after 500 cycles at 2 Ag -1 . For CNTs@C@MoS 2 , it exhibits a specific capacity of 1395 mAh g -1 , superior rate performance of 727 mAh g -1 at 5 Ag -1 , and long cycle stability (796 mAh g -1 after 500 cycles at 2 Ag -1 ). The enhanced electrochemical properties of the electrodes are probably ascribed to their amorphous nature, the combination of CNTs@C that adhered and hindered the agglomeration of CoS 2 and MoS 2 as well as the enhanced electronic conductivity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Adsorption of Direct Blue 53 dye from aqueous solutions by multi-walled carbon nanotubes and activated carbon.

    PubMed

    Prola, Lizie D T; Machado, Fernando M; Bergmann, Carlos P; de Souza, Felipe E; Gally, Caline R; Lima, Eder C; Adebayo, Matthew A; Dias, Silvio L P; Calvete, Tatiana

    2013-11-30

    Multi-walled carbon nanotubes (MWCNT) and powder activated carbon (PAC) were used as adsorbents for adsorption of Direct Blue 53 dye (DB-53) from aqueous solutions. The adsorbents were characterised using Raman spectroscopy, N2 adsorption/desorption isotherms, and scanning and transmission electron microscopy. The effects of initial pH, contact time and temperature on adsorption capacity of the adsorbents were investigated. At pH 2.0, optimum adsorption of the dye was achieved by both adsorbents. Equilibrium contact times of 3 and 4 h were achieved by MWCNT and PAC adsorbents, respectively. The general order kinetic model provided the best fit of the experimental data compared to pseudo-first order and pseudo-second order kinetic adsorption models. For DB-53 dye, the equilibrium data (298-323 K) were best fitted to the Sips isotherm model. The maximum sorption capacity for adsorption of the dye occurred at 323 K, with the values of 409.4 and 135.2 mg g(-1) for MWCNT and PAC, respectively. Studies of adsorption/desorption were conducted and the results showed that DB-53 loaded MWCNT could be regenerated (97.85%) using a mixture 50% acetone + 50% of 3 mol L(-1) NaOH. Simulated dye house effluents were used to evaluate the application of the adsorbents for effluent treatment (removal of 99.87% and 97.00% for MWCNT and PAC, respectively, were recorded). Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. ;Green; carbon with hierarchical three dimensional porous structure derived from - Pongamia pinnata seed oil extract cake and NiCo2O4-Ni(OH)2/Multiwall carbon nanotubes nanocomposite as electrode materials for high performance asymmetric supercapacitor

    NASA Astrophysics Data System (ADS)

    Chaitra, K.; Narendra, Reddy; Venkatesh, Krishna; Nagaraju, N.; Kathyayini, Nagaraju

    2017-07-01

    Herein, we report for the first time synthesis and electrochemical supercapacitance performance of 3-D hierarchical porous "Green" carbon derived from Pongamia pinnata seed oil extract cake and its activation using different amounts of KOH. Also, nanocomposites of multiwalled carbon nanotubes (MWCNT) with various weight percentages of Ni and Co were prepared by hydrothermal method. Physico-chemical properties of "Green" carbon and nanocomposites were analyzed by Powder X-ray Diffraction, Brunner Emmett Teller surface area, Scanning Electron Microscopy-Elemental Dispersive Spectrum, Transmission Electron Microscopy and Raman techniques. KOH activated carbon was found associated with combination of micropores & mesopores while the nanocomposite with mixture of spinel NiCo2O4 and Ni(OH)2. Porous carbon activated with 2:1::KOH:C (KC2) and the nanocomposite with 1:1 Ni & Co (NC1) exhibited excellent electrochemical performance in three electrode system. Further, fabricated asymmetric supercapacitor (AS) device Ni-Co-MWCNT (NC1)//KC2 exhibited specific capacitance (Cs) of 177 F/g as determined by cyclic voltammetry at 10 mV/s and retained 90% even at 3000th cycle in life cycle test conducted at high current density of 50 A/g. In order to evaluate its practical performance, the AS device was charged to 1.8 V at 5 A/g and used successfully to power a calculator for more than 1 h.

  11. An enhanced electrochemical platform based on graphene oxide and multi-walled carbon nanotubes nanocomposite for sensitive determination of Sunset Yellow and Tartrazine.

    PubMed

    Qiu, Xinlan; Lu, Limin; Leng, Jing; Yu, Yongfang; Wang, Wenmin; Jiang, Min; Bai, Ling

    2016-01-01

    A novel electrochemical platform was designed for the simultaneous determination of Sunset Yellow (SY) and Tartrazine (TT), synthetic food dyes, by combining the signal amplification properties of graphene oxide (GO) and the excellent electronic and antifouling properties of multi-walled carbon nanotubes (MWCNTs). Stable dispersion of GO/MWCNTs composite was produced by sonication mixing. Compared with glassy carbon, MWCNTs and GO electrodes, GO/MWCNTs electrode exhibited strong enhancement effect and greatly increased the oxidation signal of SY and TT. Under optimized conditions, the enhanced anodic peak currents represented the excellent analytical performance of simultaneous detection of SY and TT in the range of 0.09-8.0 μM, with a low limit of detection of 0.025 μM for SY and 0.01 μM for TT (S/N = 3), respectively. To further validate its possible application, the proposed method was successfully used for the determination of SY and TT in orange juice with satisfactory results. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Fabrication of an electrochemical platform based on the self-assembly of graphene oxide-multiwall carbon nanotube nanocomposite and horseradish peroxidase: direct electrochemistry and electrocatalysis

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Yang, Shaojun; Zhang, Jing; Zhang, Ling; Kang, Pingli; Li, Jinghong; Xu, Jingwei; Zhou, Hua; Song, Xi-Ming

    2011-12-01

    A novel hybrid nanomaterial (GO-MWNTs) was explored based on the self-assembly of multiwall carbon nanotubes (MWNTs) and graphene oxide (GO). Compared with pristine MWNTs, such a nanocomposite could be well dispersed in aqueous solution and exhibit a negative charge. Driven by the electrostatic interaction, positively charged horseradish peroxidase (HRP) could then be immobilized onto GO-MWNTs at the surface of a glassy carbon (GC) electrode to form a HRP/GO-MWNT/GC electrode under mild conditions. TEM was used to characterize the morphology of the GO-MWNT nanocomposite. UV-vis and FTIR spectra suggested that HRP was immobilized onto the hybrid matrix without denaturation. Furthermore, the immobilized HRP showed enhanced direct electron transfer for the HRP-Fe(III)/Fe(II) redox center. Based on the direct electron transfer of the immobilized HRP, the HRP/GO-MWNT/GC electrode exhibited excellent electrocatalytic behavior to the reduction of H2O2 and NaNO2, respectively. Therefore, GO-MWNTs could provide a novel and efficient platform for the immobilization and biosensing of redox enzymes, and thus may find wide potential applications in the fabrication of biosensors, biomedical devices, and bioelectronics.

  13. Alginic Acid-Aided Dispersion of Carbon Nanotubes, Graphene, and Boron Nitride Nanomaterials for Microbial Toxicity Testing

    PubMed Central

    Chang, Chong Hyun

    2018-01-01

    Robust evaluation of potential environmental and health risks of carbonaceous and boron nitride nanomaterials (NMs) is imperative. However, significant agglomeration of pristine carbonaceous and boron nitride NMs due to strong van der Waals forces renders them not suitable for direct toxicity testing in aqueous media. Here, the natural polysaccharide alginic acid (AA) was used as a nontoxic, environmentally relevant dispersant with defined composition to disperse seven types of carbonaceous and boron nitride NMs, including multiwall carbon nanotubes, graphene, boron nitride nanotubes, and hexagonal boron nitride flakes, with various physicochemical characteristics. AA’s biocompatibility was confirmed by examining AA effects on viability and growth of two model microorganisms (the protozoan Tetrahymena thermophila and the bacterium Pseudomonas aeruginosa). Using 400 mg·L−1 AA, comparably stable NM (200 mg·L−1) stock dispersions were obtained by 30-min probe ultrasonication. AA non-covalently interacted with NM surfaces and improved the dispersibility of NMs in water. The dispersion stability varied with NM morphology and size rather than chemistry. The optimized dispersion protocol established here can facilitate preparing homogeneous NM dispersions for reliable exposures during microbial toxicity testing, contributing to improved reproducibility of toxicity results. PMID:29385723

  14. Alginic Acid-Aided Dispersion of Carbon Nanotubes, Graphene, and Boron Nitride Nanomaterials for Microbial Toxicity Testing.

    PubMed

    Wang, Ying; Mortimer, Monika; Chang, Chong Hyun; Holden, Patricia A

    2018-01-30

    Robust evaluation of potential environmental and health risks of carbonaceous and boron nitride nanomaterials (NMs) is imperative. However, significant agglomeration of pristine carbonaceous and boron nitride NMs due to strong van der Waals forces renders them not suitable for direct toxicity testing in aqueous media. Here, the natural polysaccharide alginic acid (AA) was used as a nontoxic, environmentally relevant dispersant with defined composition to disperse seven types of carbonaceous and boron nitride NMs, including multiwall carbon nanotubes, graphene, boron nitride nanotubes, and hexagonal boron nitride flakes, with various physicochemical characteristics. AA's biocompatibility was confirmed by examining AA effects on viability and growth of two model microorganisms (the protozoan Tetrahymena thermophila and the bacterium Pseudomonas aeruginosa ). Using 400 mg·L -1 AA, comparably stable NM (200 mg·L -1 ) stock dispersions were obtained by 30-min probe ultrasonication. AA non-covalently interacted with NM surfaces and improved the dispersibility of NMs in water. The dispersion stability varied with NM morphology and size rather than chemistry. The optimized dispersion protocol established here can facilitate preparing homogeneous NM dispersions for reliable exposures during microbial toxicity testing, contributing to improved reproducibility of toxicity results.

  15. Mechanical and Combustion Performance of Multi-Walled Carbon Nanotubes as an Additive to Paraffin-Based Solid Fuels for Hybrid Rockets

    NASA Technical Reports Server (NTRS)

    Larson, Daniel B.; Boyer, Eric; Wachs, Trevor; Kuo, Kenneth, K.; Koo, Joseph H.; Story, George

    2012-01-01

    Paraffin-based solid fuels for hybrid rocket motor applications are recognized as a fastburning alternative to other fuel binders such as HTPB, but efforts to further improve the burning rate and mechanical properties of paraffin are still necessary. One approach that is considered in this study is to use multi-walled carbon nanotubes (MWNT) as an additive to paraffin wax. Carbon nanotubes provide increased electrical and thermal conductivity to the solid-fuel grains to which they are added, which can improve the mass burning rate. Furthermore, the addition of ultra-fine aluminum particles to the paraffin/MWNT fuel grains can enhance regression rate of the solid fuel and the density impulse of the hybrid rocket. The multi-walled carbon nanotubes also present the possibility of greatly improving the mechanical properties (e.g., tensile strength) of the paraffin-based solid-fuel grains. For casting these solid-fuel grains, various percentages of MWNT and aluminum particles will be added to the paraffin wax. Previous work has been published about the dispersion and mixing of carbon nanotubes.1 Another manufacturing method has been used for mixing the MWNT with a phenolic resin for ablative applications, and the manufacturing and mixing processes are well-documented in the literature.2 The cost of MWNT is a small fraction of single-walled nanotubes. This is a scale-up advantage as future applications and projects will require low cost additives to maintain cost effectiveness. Testing of the solid-fuel grains will be conducted in several steps. Dog bone samples will be cast and prepared for tensile testing. The fuel samples will also be analyzed using thermogravimetric analysis and a high-resolution scanning electron microscope (SEM). The SEM will allow for examination of the solid fuel grain for uniformity and consistency. The paraffin-based fuel grains will also be tested using two hybrid rocket test motors located at the Pennsylvania State University s High Pressure

  16. Promotion of lung adenocarcinoma following inhalation exposure to multi-walled carbon nanotubes

    PubMed Central

    2014-01-01

    Background Engineered carbon nanotubes are currently used in many consumer and industrial products such as paints, sunscreens, cosmetics, toiletries, electronic processes and industrial lubricants. Carbon nanotubes are among the more widely used nanoparticles and come in two major commercial forms, single-walled carbon nanotubes (SWCNT) and the more rigid, multi-walled carbon nanotubes (MWCNT). The low density and small size of these particles makes respiratory exposures likely. Many of the potential health hazards have not been investigated, including their potential for carcinogenicity. We, therefore, utilized a two stage initiation/promotion protocol to determine whether inhaled MWCNT act as a complete carcinogen and/or promote the growth of cells with existing DNA damage. Six week old, male, B6C3F1 mice received a single intraperitoneal (ip) injection of either the initiator methylcholanthrene(MCA, 10 μg/g BW, i.p.), or vehicle (corn oil). One week after i.p. injections, mice were exposed by inhalation to MWCNT (5 mg/m3, 5 hours/day, 5 days/week) or filtered air (controls) for a total of 15 days. At 17 months post-exposure, mice were euthanized and examined for lung tumor formation. Results Twenty-three percent of the filtered air controls, 26.5% of the MWCNT-exposed, and 51.9% of the MCA-exposed mice, had lung bronchiolo-alveolar adenomas and lung adenocarcinomas. The average number of tumors per mouse was 0.25, 0.81 and 0.38 respectively. By contrast, 90.5% of the mice which received MCA followed by MWCNT had bronchiolo-alveolar adenomas and adenocarcinomas with an average of 2.9 tumors per mouse 17months after exposure. Indeed, 62% of the mice exposed to MCA followed by MWCNT had bronchiolo-alveolar adenocarcinomas compared to 13% of the mice that received filtered air, 22% of the MCA-exposed, or 14% of the MWCNT-exposed. Mice with early morbidity resulting in euthanasia had the highest rate of metastatic disease. Three mice exposed to both MCA and

  17. Proficiency feasibility of multi-walled carbon nanotubes in the presence of polymeric surfactant on enhanced oil recovery

    NASA Astrophysics Data System (ADS)

    Nezhad, Javad Razavi; Jafari, Arezou; Abdollahi, Mahdi

    2018-01-01

    Enhanced heavy oil recovery methods are widely utilized to increase oil recovery. For this purpose, polymer and surfactant flooding have been used extensively. Recently, polymeric surfactant flooding has become an attractive alternative to sole polymer flooding due to their capability of providing an increase in solution viscosity and a decrease in interfacial tension, which are both beneficial for efficiency of the process. Applying nanoparticles as an additive to polymer solutions is a method to improve viscosity and alter rock wettability. Therefore, in this research, multi-walled carbon nanotube (MWCNT) was mixed with a polymeric surfactant of polyacrylamide-graft-lignin copolymer (PAM-g-L) synthesized via radical grafting reaction. Moreover, several solutions with different concentrations of nanoparticles with PAM-g-L were prepared. The solutions were injected into a micromodel to evaluate the PAM-g-L flooding efficiency in presence of the multi-walled carbon nanotubes. The results of micromodel flooding showed that increasing MWCNT concentration results in lower sweep efficiencies; and consequently, oil production will decrease. Therefore, MWCNT along with PAM-g-L has an unacceptable performance in enhanced heavy oil recovery. But data of wettability tests revealed that MWCNT can change the wettability from oil-wet to water-wet. In addition, the combination of the PAM-g-L and MWCNT in a solution will cause more water-wet condition.

  18. Detection of Quinoline in G. boninense-Infected Plants Using Functionalized Multi-Walled Carbon Nanotubes: A Field Study.

    PubMed

    Akanbi, Fowotade Sulayman; Yusof, Nor Azah; Abdullah, Jaafar; Sulaiman, Yusran; Hushiarian, Roozbeh

    2017-07-01

    Carbon nanotubes (CNTs) reinforced with gold nanoparticles (AuNPs) and chitosan nanoparticles (CTSNPs) were anchored on a screen-printed electrode to fabricate a multi-walled structure for the detection of quinoline. The surface morphology of the nanocomposites and the modified electrode was examined by an ultra-high resolution field emission scanning electron microscope (FESEM), and Fourier-transform infrared (FT-IR) spectroscopy was used to confirm the presence of specific functional groups on the multi-walled carbon nanotubes MWCNTs. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were used to monitor the layer-by-layer assembly of ultra-thin films of nanocomposites on the surface of the electrode and other electrochemical characterizations. Under optimized conditions, the novel sensor displayed outstanding electrochemical reactivity towards the electro-oxidation of quinoline. The linear range was fixed between 0.0004 and 1.0 μM, with a limit of detection (LOD) of 3.75 nM. The fabricated electrode exhibited high stability with excellent sensitivity and selectivity, specifically attributable to the salient characteristics of AuNPs, CTSNPs, and MWCNTs and the synergistic inter-relationship between them. The newly developed electrode was tested in the field. The Ipa increased with an increase in the amount of quinoline solution added, and the peak potential deviated minimally, depicting the real capability of the newly fabricated electrode.

  19. Polymeric monolith column composited with multiwalled carbon nanotubes-β-cyclodextrin for the selective extraction of psoralen and isopsoralen.

    PubMed

    Ling, Xu; Zou, Li; Chen, Zilin

    2017-09-01

    A polymeric column that contains multiwalled carbon nanotubes-β-cyclodextrin composite was developed. The composite was wrapped into the poly(butyl methacrylate-ethylene dimethacrylate) monolith column (0.76 mm id and 10 cm in length). The column was then applied for the online solid-phase microextraction of psoralen and isopsoralen from Fructus Psoraleae. Following microextraction, the coumarins were quantified by high-performance liquid chromatography with C 18 separation column and UV detection. The effects of sample flow rate, sample volume, and pH value were optimized. The method showed low limits of detection (20 pg/mL, S/N = 3) for both psoralen and isopsoralen. Finally the method was successfully applied to the determination of psoralen and isopsoralen in spiked herb extracts and rat plasma where it gave recoveries that ranged between 93.2 and 102.1%. The empty hydrophobic cavities of β-cyclodextrin and the hydrophobicity of multiwalled carbon nanotubes provided specific extraction capability for psoralen and isopsoralen. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Detection of Quinoline in G. boninense-Infected Plants Using Functionalized Multi-Walled Carbon Nanotubes: A Field Study

    PubMed Central

    Akanbi, Fowotade Sulayman; Yusof, Nor Azah; Abdullah, Jaafar; Sulaiman, Yusran; Hushiarian, Roozbeh

    2017-01-01

    Carbon nanotubes (CNTs) reinforced with gold nanoparticles (AuNPs) and chitosan nanoparticles (CTSNPs) were anchored on a screen-printed electrode to fabricate a multi-walled structure for the detection of quinoline. The surface morphology of the nanocomposites and the modified electrode was examined by an ultra-high resolution field emission scanning electron microscope (FESEM), and Fourier-transform infrared (FT-IR) spectroscopy was used to confirm the presence of specific functional groups on the multi-walled carbon nanotubes MWCNTs. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were used to monitor the layer-by-layer assembly of ultra-thin films of nanocomposites on the surface of the electrode and other electrochemical characterizations. Under optimized conditions, the novel sensor displayed outstanding electrochemical reactivity towards the electro-oxidation of quinoline. The linear range was fixed between 0.0004 and 1.0 μM, with a limit of detection (LOD) of 3.75 nM. The fabricated electrode exhibited high stability with excellent sensitivity and selectivity, specifically attributable to the salient characteristics of AuNPs, CTSNPs, and MWCNTs and the synergistic inter-relationship between them. The newly developed electrode was tested in the field. The Ipa increased with an increase in the amount of quinoline solution added, and the peak potential deviated minimally, depicting the real capability of the newly fabricated electrode. PMID:28671561