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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. 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.

  3. The Dispersion State of Tangled Multi-Walled Carbon Nanotubes Affects Their Cytotoxicity.

    PubMed

    Kuroda, Chika; Haniu, Hisao; Ajima, Kumiko; Tanaka, Manabu; Sobajima, Atsushi; Ishida, Haruka; Tsukahara, Tamotsu; Matsuda, Yoshikazu; Aoki, Kaoru; Kato, Hiroyuki; Saito, Naoto

    2016-11-19

    The medical applications of carbon nanotubes (CNTs) have garnered much attention. However, evaluating the safety of CNTs remains difficult, and no consensus has been reached. Moreover, assessing the biosafety of multi-walled CNTs (MWCNTs), which can become tangled during manufacturing, is challenging because they do not readily disperse. We studied how the dispersion state of tangled MWCNTs affects their cytotoxicity, using three sonicators. Flotube 9110 (FT9110), tangled MWCNTs, were dispersed in two dispersants (fetal bovine serum and polysorbate 80) using a new type of sonicator (PR-1) and two conventional sonicators. The size and cytotoxicity of the dispersed FT9110 were measured using the BEAS-2B human bronchial epithelial cell line. The PR-1 dispersed the FT9110 to agglomerates <200 nm in diameter; FT9110 dispersed with the PR-1 did not show cytotoxicity regardless of dispersant. The other sonicators dispersed the FT9110 to particles >1000 nm in diameter, and cytotoxicity depended on the dispersant. We found that excluding cells adhered to agglomerated FT9110 before evaluating cytotoxicity can lead to false-positive results. The PR-1 sonicator dispersed tangled FT9110 to many single fibers, which showed lower cytotoxicity than conventionally-sonicated MWCNTs. We suggest that dispersion state should be accounted for when evaluating the cytotoxicity of MWCNTs.

  4. Improvement of interaction between pre-dispersed multi-walled carbon nanotubes and unsaturated polyester resin

    NASA Astrophysics Data System (ADS)

    Beg, M. D. H.; Moshiul Alam, A. K. M.; Yunus, R. M.; Mina, M. F.

    2015-01-01

    Efforts are being given to the development of well-dispersed nanoparticle-reinforced polymer nanocomposites in order to tailor the material properties. In this perspective, well dispersion of multi-walled carbon nanotubes (MWCNTs) in unsaturated polyester resin (UPR) was prepared using pre-dispersed MWCNTs in tetrahydrofuran solvent with ultrasonication method. Then the well-dispersed MWCNTs reinforced UPR nanocomposites were fabricated through solvent evaporation. Fourier-transform infrared spectroscopy indicates a good interaction between matrix and MWCNTs. This along with homogeneous dispersion of nanotubes in matrix has been confirmed by the field emission scanning electron microscopy. At low shear rate, the value of viscosity of UPR is 8,593 mPa s and that of pre-dispersed MWCNT-UPR suspension is 43,491 mPa s, showing implicitly a good dispersion of nanotubes. A notable improvement in the crystallinity of UPR from 14 to 21 % after MWCNTs inclusion was observed by X-ray diffractometry. The mechanical properties, such as tensile strength, tensile modulus, impact strength, and elongation-at-break, of nanocomposite were found to be increased to 22, 20, 28, and 87 %, respectively. The estimated melting enthalpy per gram for composites as analyzed by differential scanning calorimetry is higher than that of UPR. The onset temperature of thermal decomposition in the nanocomposites as monitored by thermogravimetric analysis is found higher than that of UPR. Correlations among MWCNTs dispersion, nucleation, fracture morphology, and various properties were measured and reported.

  5. 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

  6. 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.

  7. The preparation of lysine modified multi-walled carbon nanotubes and the study of its dispersion properties

    NASA Astrophysics Data System (ADS)

    Lu, Hongwei; Zou, Liming; Wei, Yizhe; Ling, Xinlong; Xu, Yongjing

    2015-07-01

    The poor dispersion in aqueous solution limited the application of carbon nanotubes (CNTs) in biological field. Here we used DCC/DMAP as Catalysis to prepare lysine modified multi-walled carbon nanotubes (MWNTs). FT-IR and TGA demonstrated that lysine have been successfully grafted to MWNTs, EA showed that lysine graft rate up to 23.4%. The dispersion of lysine modified MWNTs was investigated by direct visual inspection and microscope observation, the result showed that lysine modified MWNTs can be dispersed in aqueous solution and keep stable for long time.

  8. 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.

  9. 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.

  10. 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

  11. New practical method of homogeneous dispersion of multi-walled carbon nanotubes (MWCNTs) into Mg matrix composites

    NASA Astrophysics Data System (ADS)

    Zhang, Teng; Du, Shuangming; Sun, Wanchang; Zhang, Jumei; Niu, Libin; Hua, Xiaohu

    2017-03-01

    It is difficult to disperse multi-walled carbon nanotubes (MWCNTs) into Mg matrix composites homogeneously due to the high specific surface energy between MWCNTs. This would affect the mechanical properties of magnesium matrix composites reinforced by MWCNTs tremendously. The key is to overcome MWCNTs aggregate together, and gain the homogeneous dispersion of MWCNTs. Moreover, the density difference of Mg matrix and MWCNTs is another problem which prevents MWCNTs from dispersing homogeneously into Mg matrix composites. In order to solve these problems, a new practical method of homogeneous dispersion of carbon nanotubes into Mg matrix composites was presented basing on combination the tow step ball milling and ultrasonication dispersion methods. First, a certain amount of MWCNTs was ball-milled in ethanol solution contain 5 wt.% sodium stearate at various rotation speeds (100 rpm-300 rpm) and ball-milled times (0.5 H-2 H) to break MWCNTs hard aggregation. Second, MWCNTs which were subjected to the ball-milling were dispersed further in ethanol solution containing (SDS, DBS) using ultrasonication method. Third, the Mg powers were mixed with good dispersion of carbon nanotubes solution and ball-milled for 1 H to make MWCNTs coated uniformly on the surface of the magnesium substrate. The results were mainly examined by field emission scanning electron microscopy (SEM). It was found that MWCNTs were dispersed well and some of these MWCNTs had directional arrangement. Furthermore, MWCNTs were homogeneously dispersed into Mg matrix composites. These results suggest that this method has good application for magnesium matrix composites reinforced by carbon nanotubes.

  12. Towards highly stable aqueous dispersions of multi-walled carbon nanotubes: the effect of oxygen plasma functionalization.

    PubMed

    Garzia Trulli, Marta; Sardella, Eloisa; Palumbo, Fabio; Palazzo, Gerardo; Giannossa, Lorena Carla; Mangone, Annarosa; Comparelli, Roberto; Musso, Simone; Favia, Pietro

    2017-04-01

    In order to improve the dispersion of multi-walled carbon nanotubes (MWCNTs) in aqueous media, their surface functionalization was carried out in O 2 -fed low-pressure plasmas. Differently from what can be found in the literature of this field, homogeneous functionalization was achieved by generating the plasma inside vials containing the nanotube powders properly stirred. Experimental parameters, such as input power, treatment time and pressure, were varied to investigate their influence on the process efficiency. A detailed characterization of the plasma treated nanotubes, dry and in aqueous suspension, was carried out with a multi-diagnostic analytical approach, to evaluate their surface chemical properties, morphology, structural integrity and stability in the colloidal state. The plasma grafting of polar ionizable (e.g. acid) groups has been proved to successfully limit the agglomeration of MWCNTs and to produce nanotubes suspensions that are stable for one month and more in water. Copyright © 2016 Elsevier Inc. All rights reserved.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27966549

  14. p-Phosphonic acid calix[8]arene assisted dispersion and stabilisation of pea-pod C60@multi-walled carbon nanotubes in water.

    PubMed

    Chen, Xianjue; Gibson, Christopher T; Britton, Joshua; Eggers, Paul K; Wahid, M Haniff; Raston, Colin L

    2015-02-11

    A facile approach has been developed for non-covalently stabilising pristine C60 and multi-walled carbon nanotubes (MWCNTs) in water in the presence of p-phosphonic acid calix[8]arene, along with the formation of a 'pea-pod' encapsulation of the fullerene inside the MWCNTs. Aqueous dispersions of the different carbon nano-materials are readily decorated with palladium nanoparticles.

  15. 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.

  16. SiO2 coated Fe3O4 magnetic nanoparticle dispersed multiwalled carbon nanotubes based amperometric glucose biosensor.

    PubMed

    Baby, Tessy Theres; Ramaprabhu, S

    2010-03-15

    A new type of amperometric glucose biosensor based on silicon dioxide coated magnetic nanoparticle decorated multiwalled carbon nanotubes (Fe(3)O(4)@SiO(2)/MWNTs) on a glassy carbon electrode (GCE) has been developed. MWNTs have been synthesized by catalytic chemical vapour decomposition (CCVD) of acetylene over rare earth (RE) based AB(3) alloy hydride catalyst. The as-grown MWNTs have been purified and further functionlized. Functionalized MWNTs have been decorated with magnetic Fe(3)O(4) nanoparticles which have been uniformly coated with biocompatible SiO(2) using a simple chemical reduction method. The characterization of magnetic nanoparticle modified MWNTs have been done by X-ray diffraction (XRD), Fourier transform infra red spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM), energy dispersive X-ray analysis (EDX) and UV-vis spectroscopy. Amperometric biosensor has been fabricated by the deposition of glucose oxidase (GOD) over Nafion-solubilized Fe(3)O(4)@SiO(2)/MWNTs electrode. The resultant bioelectrode retains its biocatalytic activity and offers fast and sensitive glucose quantification. The performance of the biosensor has been studied using cyclic voltammetry and amperometry and the results have been discussed. The fabricated glucose biosensor exhibits a linear response from 1 microM to 30 mM with an excellent detection limit of 800 nM indicating the potential applications in food industries. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  17. 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.

  18. Hydrophilic modified magnetic multi-walled carbon nanotube for dispersive solid/liquid phase microextraction of sunitinib in human samples.

    PubMed

    Hooshmand, Sara; Es'haghi, Zarrin

    2018-02-01

    In this paper, a novel approach for the efficient microextraction and determination of anticancer drug, sunitinib from human samples is described. We synthesized a new nanocomposite; honey coated magnetic multi-walled carbon nanotubes (Honey@magnetic-CNTs). This nanocomposite retains the magnetic properties of individual magnetic nanoparticles (MNPs) and can be effectively separated under an external magnetic field. The synthesized nanoparticles were characterized by FT-IR, VSM, EDAX and XRD and TEM studies. The spherical particles obtained before and after the functionalization had sizes of 14 nm and 16 nm, respectively. The method is based on Honey@magnetic-CNTs assisted dispersive solid-liquid phase microextraction for determination and analysis of the drug. The influences of experimental parameters were investigated. Under optimal conditions, the applied nanocomposite showed good performance, high sensitivity and fast extraction of the analyte from biological samples. In linearity test, the regression correlation coefficient was obtained more than 99% for analyte of interest and linear dynamic range for the proposed method was from 5 to 5000 ng mL -1 . Method detection and quantification limits were 1.58 ng mL -1 and 5.28 ng mL -1 , respectively. Relative standard deviation was 3.15%. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Synthesis, characterization and cytotoxicity of surface amino-functionalized water-dispersible multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Vuković, Goran; Marinković, Aleksandar; Obradović, Maja; Radmilović, Velimir; Čolić, Miodrag; Aleksić, Radoslav; Uskoković, Petar S.

    2009-06-01

    Surface functionalization of multi-walled carbon nanotubes (MWCNTs), with amino groups via chemical modification of carboxyl groups introduced on the nanotube surface, using O-(7-azabenzotriazol-1-yl)- N, N, N', N'-tetramethyluronium hexafluorophosphate (N-HATU) and N, N-diisopropylethylamine (DIEA) is reported. The N-HATU coupling agent provides faster reaction rate and the reaction occurs at lower temperature compared to amidation and acylation-amidation chemistry. The amines, 1,6-hexanediamine (HDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and 1,4-phenylenediamine (PDA) were used. The resulting materials were characterized with different techniques such as FTIR, XRD, elemental analysis, TGA, TEM, UV-vis spectroscopy and cyclic voltammetry. MWCNTs functionalized with PDA posses the best dispersibility and electron transfer properties in comparison to the others amines. Functionalized MWCNTs, at the concentrations between 1 and 50 μg ml -1, were not cytotoxic for the fibroblast L929 cell line. However, the concentrations of MWCNTs higher of 10 μg ml -1 reduced cell growth and this effect correlated positively with the degree of their uptake by L929 cells.

  20. Effective functionalization of multiwalled carbon nanotube with amphiphilic poly(propyleneimine) dendrimer carrying silver nanoparticles for better dispersability and antimicrobial activity.

    PubMed

    Murugan, E; Vimala, G

    2011-05-15

    Two multiwalled carbon nanotube hybrids have been prepared: (a) multiwalled carbon nanotubes (MWCNTs) functionalized with amphiphilic poly(propyleneimine) dendrimer (APPI), viz. MWCNTs-APPI, and (b) silver nanoparticles (AgNPs)-deposited multiwalled carbon nanotubes functionalized with an amphiphilic poly(propyleneimine) dendrimer (MWCNTs-APPI-AgNPs). The degree of covalent functionalization of APPI in MWCNTs and deposition of AgNPs in MWCNTs-APPI were examined by Fourier transform infrared spectroscopy, zeta potential, scanning and high-resolution transmission electron microscopy, energy-dispersive spectroscopy, thermogravimetric analysis, and Raman spectroscopy. The amount of APPI functionalized on MWCNTs determined by thermal gravimetric analysis was about 67% which enables an effective dispersability in aqueous and organic solvents without sonication and these solutions were stable for 6 months without undergoing aggregation of MWCNTs. The electronic properties of the hybrid materials were not altered drastically as verified by the Raman studies. The antimicrobial activities of MWCNTs-APPI and MWCNTs-APPI-AgNPs against three different bacteria, viz. Bacillus subtilis, Staphylococcus aureus, and Escheriachia coli illustrated excellent activity. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. 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.

  2. Dispersive cleanup of acetonitrile extracts of tea samples by mixed multiwalled carbon nanotubes, primary secondary amine, and graphitized carbon black sorbents.

    PubMed

    Zhao, Pengyue; Wang, Lei; Jiang, Yaping; Zhang, Fengzu; Pan, Canping

    2012-04-25

    A method for analysis of 37 pesticide residues in tea samples was developed and validated and was based on reversed-dispersive solid-phase extraction (r-DSPE) cleanup in acetonitrile solution, followed by liquid chromatography-electrospray tandem mass spectrometry determination. Green tea, oolong tea, and puer tea were selected as matrixes and represent the majority of tea types. Acetonitrile was used as the extraction solvent, with sodium chloride and magnesium sulfate enhancing partitioning of analytes into the organic phase. The extract was then cleaned up by r-DSPE using a mixture of multiwalled carbon nanotubes, primary secondary amine, and graphitized carbon black as sorbents to absorb interferences. Further optimization of sample preparation and determination allowed recoveries of between 70% and 111% for all 37 pesticides with relative standard deviations lower than 14% at two concentration levels of 10 and 100 μg kg(-1). Limits of quantification ranged from 5 to 20 μg kg(-1) for all pesticides. The developed method was successfully applied to the determination of pesticide residues in market tea samples.

  3. A Nicotinamide Adenine Dinucleotide Dispersed Multi-walled Carbon Nanotubes Electrode for Direct and Selective Electrochemical Detection of Uric Acid.

    PubMed

    Chen, Yan; Li, Yiwei; Ma, Yaohong; Meng, Qingjun; Yan, Yan; Shi, Jianguo

    2015-01-01

    A nanocomposite platform built with multi-walled carbon nanotubes (MWCNTs) and nicotinamide adenine dinucleotide (NAD(+)) via a noncovalent interaction between the large π systems in NAD(+) molecules and MWCNTs on a glassy carbon substrate was successfully developed for the sensitive and selective detection of uric acid (UA) in the presence of ascorbic acid (AA), dopamine (DA). NAD(+) has an adenine subunit and a nicotinamide subunit, which enabled interaction with the purine subunit of UA through a strong π-π interaction to enhance the specificity of UA. Compared with a bare glassy carbon electrode (GCE) and MWCNTs/GCE, the MWCNTs-NAD(+)/GCE showed a low background current and a remarkable enhancement of the oxidation peak current of UA. Using differential pulse voltammetry (DPV), a high sensitivity for the determination of UA was explored for the MWCNTs-NAD(+) modified electrode. A linear relationship between the DPV peak current of UA and its concentration could be obtained in the range of 0.05 - 10 μM with the detection limit as low as 10 nM (S/N = 3). This present strategy provides a novel and promising platform for the detection of UA in human urine and serum samples.

  4. Terahertz Dispersion Characteristics of Super-aligned Multi-walled Carbon Nanotubes and Enhanced Transmission through Subwavelength Apertures.

    PubMed

    Wang, Yue; Duan, Guangwu; Zhang, Liying; Ma, Lihua; Zhao, Xiaoguang; Zhang, Xin

    2018-02-01

    The terahertz (THz) dielectric properties of super-aligned multi-walled carbon nanotube (MWCNT) films were characterized in the frequency range from 0.1 to 2.5 THz with terahertz time-domain spectroscopy. The refractive index, effective permittivity, and conductivity were retrieved from the measured transmission spectra with THz incident wave polarized parallel and perpendicular to the orientation of carbon nanotubes (CNTs), and a high degree of polarization dependence was observed. The Drude-Lorentz model combined with Maxwell-Garnett effective medium theory was employed to explain the experimental results, revealing an obvious metallic behavior of the MWCNT films. Moreover, rectangular aperture arrays were patterned on the super-aligned MWCNT films with laser-machining techniques, and the transmission measurement demonstrated an extraordinarily enhanced transmission characteristic of the samples with incident wave polarized parallel to the orientation of the CNTs. Surface plasmon polaritons were employed to explain the extraordinarily enhanced transmission with high accuracy, and multi-order Fano profile was applied to model the transmission spectra. A high degree of agreement was exhibited among the experimental, numerical, and theoretical results.

  5. 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.

  6. 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.

  7. High Performance Multiwall Carbon Nanotube Bolometers

    DTIC Science & Technology

    2010-10-21

    REPORT High performance multiwall carbon nanotube bolometers 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: High infrared bolometric photoresponse has...been observed in multiwall carbon nanotube MWCNT films at room temperature. The observed detectivity D in exceeding 3.3 106 cm Hz1/2 /W on MWCNT film...U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS carbon nanotube, infrared detector, bolometer

  8. 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...

  9. Dispersive micro-solid phase extraction of aromatic amines based on an efficient sorbent made from poly(1,8-diaminonaphtalen) and magnetic multiwalled carbon nanotubes composite.

    PubMed

    Jalilian, Niloofar; Ebrahimzadeh, Homeira; Asgharinezhad, Ali Akbar

    2017-05-26

    In this work, the extraction of aromatic amines with an efficient magnetic multiwalled carbon nanotubes/Fe 3 O 4 @Poly(1,8-diaminonaphtalen) (MWCNTs/Fe 3 O 4 @PDAN) composite followed by HPLC-DAD was presented. Imprimis, the comparison among different magnetic nanosorbents including Fe 3 O 4 , MWCNTs/Fe 3 O 4 , Fe 3 O 4 @PDAN and MWCNTs/Fe 3 O 4 @PDAN was conducted. The obtained results, exhibited that the MWCNTs/Fe 3 O 4 @PDAN composite has the highest extraction efficiency for target analytes (3-nitroaniline, 4-chloroaniline, 4-bromoaniline and 3,4-dichloroaniline). This sorbent was characterized by Fourier transform infrared spectroscopy, X-ray dispersive spectroscopy, thermogravimetry analysis, scanning electron microscopy, transition electron microscopy, vibrating sample magnetometry and X-ray diffraction. Design of experiment approach was applied to find out the optimal experimental conditions. The optimal extraction conditions were: pH of the sample, 10; sorbent amount, 10mg; sorption time, 15min; salt concentration, 10% w/w; type and volume of the eluent, 0.01molL -1 HCl in acetonitrile, 145μL; elution time; 2min. Under the optimal extraction conditions detection limits and linear dynamic ranges were achieved in the range of 0.1-0.25μgL -1 and 0.25-500μgL -1 , respectively. The percent of extraction recovery and relative standard deviations (n=5) were in the range of 31.2-82.8% and 3.4-5.6%, respectively. Finally, the applicability of the method was successfully confirmed by the extraction and determination of target analytes in various water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. 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...

  11. Multiwall carbon nanotube microcavity arrays

    SciTech Connect

    Ahmed, Rajib; Butt, Haider, E-mail: h.butt@bham.ac.uk; Rifat, Ahmmed A.

    2016-03-21

    Periodic highly dense multi-wall carbon nanotube (MWCNT) arrays can act as photonic materials exhibiting band gaps in the visible regime and beyond terahertz range. MWCNT arrays in square arrangement for nanoscale lattice constants can be configured as a microcavity with predictable resonance frequencies. Here, computational analyses of compact square microcavities (≈0.8 × 0.8 μm{sup 2}) in MWCNT arrays were demonstrated to obtain enhanced quality factors (≈170–180) and narrow-band resonance peaks. Cavity resonances were rationally designed and optimized (nanotube geometry and cavity size) with finite element method. Series (1 × 2 and 1 × 3) and parallel (2 × 1 and 3 × 1) combinations of microcavities were modeled and resonance modesmore » were analyzed. Higher order MWCNT microcavities showed enhanced resonance modes, which were red shifted with increasing Q-factors. Parallel microcavity geometries were also optimized to obtain narrow-band tunable filtering in low-loss communication windows (810, 1336, and 1558 nm). Compact series and parallel MWCNT microcavity arrays may have applications in optical filters and miniaturized optical communication devices.« less

  12. 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.

  13. 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.

  14. Chemically modified multiwalled carbon nanotubes improve the cytocompatibility

    NASA Astrophysics Data System (ADS)

    Guo, Ya-Ke; Chen, Wen; Xiong, Qing; Ren, Quan-Xia; Sun, Li; Han, Bo; Li, Xiao-Juan

    2017-12-01

    Multiwalled carbon nanotubes (MWCNTs) have been widely used in materials science. This study was designed to evaluate the dispersions and cytocompatibilities of chemically modified MWCNTs, carboxyl MWCNTs (MWCNTs-COOH) were separately reacted with ethylenediamine (EDA) and polyethyleneimine (PEI) via thionyl chloride, as well as polyamideamine (PAMAM) via EDC-NHS click chemistry. Chemically modified MWCNTs were successfully obtained and characterized by TEM, FTIR, and TGA. The dispersities of MWCNTs were measured as: MWCNTs-COOH  <  MWCNTs-PAMAM  <  MWCNTs-EDA  <  MWCNTs-PEI. MTT assay demonstrated chemically modified MWCNTs improved the cytocompatibilities compared to the unmodified MWCNTs, and the cytotoxicity of MWCNTs-PEI was least (P  <  0.05). Therefore, chemically modified MWCNTs can increase the dispersion of MWCNTs and improve their cytocompatibilities.

  15. 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.

  16. Enzymatic degradation of multiwalled carbon nanotubes.

    PubMed

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

    2011-09-01

    Because of their unique properties, carbon nanotubes and, in particular, multiwalled carbon nanotubes (MWNTs) have been used for the development of advanced composite and catalyst materials. Despite their growing commercial applications and increased production, the potential environmental and toxicological impacts of MWNTs are not fully understood; however, many reports suggest that they may be toxic. Therefore, a need exists to develop protocols for effective and safe degradation of MWNTs. In this article, we investigated the effect of chemical functionalization of MWNTs on their enzymatic degradation with horseradish peroxidase (HRP) and hydrogen peroxide (H(2)O(2)). We investigated HRP/H(2)O(2) degradation of purified, oxidized, and nitrogen-doped MWNTs and proposed a layer-by-layer degradation mechanism of nanotubes facilitated by side wall defects. These results provide a better understanding of the interaction between HRP and carbon nanotubes and suggest an eco-friendly way of mitigating the environmental impact of nanotubes. © 2011 American Chemical Society

  17. 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.

  18. Preparation and characterization of polycarbonate/multiwalled carbon nanotube nanocomposites.

    PubMed

    Larosa, Claudio; Patra, Niranjan; Salerno, Marco; Mikac, Lara; Merijs Meri, Remo; Ivanda, Mile

    2017-01-01

    A polymer nanocomposite was produced by ultrasonic-assisted dispersion of multiwalled carbon nanotubes (MWCNTs) in a polycarbonate matrix using p -xylene and dichloromethane as the solvents. The filler loading was varied from 1 to 3 wt % in order to examine the effect of MWCNTs on the structure and properties of the composites. The nanocomposites were characterized by DSC, DTA, TGA, UV-vis, FTIR and Raman spectroscopy to evaluate the changes induced by the filler in the polymer matrix. UV-vis, FTIR and Raman spectroscopy measurements confirmed the presence of the dispersed phase in the composite films, while TGA and DSC analysis of the nanocomposites revealed enhanced thermal stability and decreased crystallinity, respectively, as compared to the neat polymer. The proposed composites can find application in a number of everyday products where polycarbonate is the base polymer.

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

    PubMed

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

    2013-11-15

    In this manuscript, a new method based on the use of off-line dispersive solid-phase extraction (dSPE) combined with ultra-high performance liquid chromatography with diode-array detection was developed to determine 11 sulfonamide antibiotics (sulfanilamide, sulfacetamide, sulfadiazine, sulfathiazole, sulfamerazine, sulfadimidin, sulfamethoxypyridazine, sulfadoxine, sulfamethoxazole, sulfisoxazole and sulfadimethoxine) in mineral waters with different mineral content. For this purpose, pristine multi-walled carbon nanotubes (MWCNTs) and magnetic-MWCNTs (m-MWCNTs) were used as sorbents. Magnetic nanoparticles were synthesized by means of a solvothermal process, assembled onto CNTs through an "aggregation wrap" mechanism and characterized by scanning electron microscopy. Parameters affecting the extraction such as volume and pH of the sample, amount of sorbent and type and volume of eluent were optimized. Once optimum extraction conditions (250 mL of water at pH 6.0 and elution with 25 mL of MeOH) were obtained, the extraction efficiency of the different carbon nanomaterials was compared. Results demonstrated the higher extraction capacity of pristine MWCNTs with recoveries between 61 and 110% (except for sulfacetamide which ranged between 40 and 53%) and between 22 and 77% for m-MWCNTs. Limits of detection lower than 32 ng/L were achieved for all of the analyzed samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Spectroscopic investigations on epoxy--multiwall carbon nanotubes composites.

    PubMed

    Ali, Nasar; Chipara, Mircea; Bai, J B

    2011-10-01

    Room temperature electron spin resonance spectra of epoxy resins loaded with various concentrations of multiwalled carbon nanotubes of various lengths are analyzed. The resonance spectrum near the free electron line position is dominated by a single almost symmetric line assigned to delocalized electrons residing on multiwalled carbon nanotubes. The experimental research shown that: (1) The dependence of the g-factor on nanotubes length is controlled by the distortions of multiwalled carbon nanotubes. (2) The dependence of the g-factor on the concentration of multi-walled nanotubes reflects the interactions between electrons localized on different nanotubes. In insulating composites, the resonance line width broadens as the length and the concentration of multiwalled carbon nanotubes is increased. (3) For conducting composites, the dependence of the electron spin resonance line width on the length and concentration of multiwalled carbon nanotubes is controlled by Elliott contribution and exchange interactions, respectively. (4) The concentration of conduction electrons increases as the length and the concentration of multiwalled carbon nanotubes are increased.

  1. The comparison of dispersive solid phase extraction and multi-plug filtration cleanup method based on multi-walled carbon nanotubes for pesticides multi-residue analysis by liquid chromatography tandem mass spectrometry.

    PubMed

    Qin, Yuhong; Zhao, Pengyue; Fan, Sufang; Han, Yongtao; Li, Yanjie; Zou, Nan; Song, Shuangyu; Zhang, Yuan; Li, Fangbing; Li, Xuesheng; Pan, Canping

    2015-03-13

    In this study, dispersive-Solid Phase Extraction (d-SPE) cleanup and multi-plug filtration cleanup (m-PFC) methods were compared for 25 representative pesticides in six matrices (wheat, spinach, carrot, apple, citrus and peanut) by QuEChERS-LC-ESI-MS/MS detection. The type of sorbents in dispersive-SPE (d-SPE) was optimized for the above matrices. Multi-walled carbon nanotubes (MWCNTs), which mixed other materials like PSA (Primary Secondary Amines), GCB (Graphitized Carbon Black) and C18 (Octadecyl-silica), showed brilliant cleanup performance in multi residue monitoring (MRM) pesticide residue analysis. Cleanup effects with d-SPE and m-PFC methods were examined. When spiked at 3 concentration levels of 10, 100, 500 μg/kg in above matrices, for both d-SPE and m-PFC methods, the recoveries ranged from 70 to 110% with relative standard deviations (RSDs) lower than 20%. Limits of quantification (LOQs) for both cleanup methods ranged from 1 to 25 μg/kg. Matrix-matched calibrations were performed with the coefficients of determination more than 0.99 between concentration levels of 10-1000 μg/kg. It was found that m-PFC was more convenient and effective than d-SPE with the same sorbents, due to the increased contact time and contact area between the extracts and compressed sorbents. The study demonstrated that m-PFC method could be used as a rapid, convenient and high-throughput cleanup method for analysis of pesticide residues. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Dispersive micro-solid phase extraction using magnetic nanoparticle modified multi-walled carbon nanotubes coupled with surfactant-enhanced spectrofluorimetry for sensitive determination of lomefloxacin and ofloxacin from biological samples.

    PubMed

    Amoli-Diva, Mitra; Pourghazi, Kamyar; Hajjaran, Somayeh

    2016-03-01

    A dispersive micro-solid-phase extraction (D-μ-SPE) procedure coupled with surfactant-enhanced spectrofluorimetric detection was developed for determination of ofloxacin and lomefloxacin from biological and environmental samples. The D-μ-SPE procedure was performed using magnetic Fe3O4 nanoparticle grafted multi-walled carbon nanotube as an efficient adsorbent. The main factors affecting the signal enhancement (including surfactant concentration and pH) and extraction efficiency (including pH, extraction time, sample volume, amount of magnetic adsorbent, and desorption conditions) were investigated in detail. Under the optimized conditions, the calibration curves were linear (R(2)˃0.9995) over the concentration range of 50-450 ng mL(-1) with detection limits (LOD) of 12 and 15 ng mL(-1) for ofloxacin and lomefloxacin respectively. The relative standard deviation (RSD %) of 1.9 and 2.1% (C=100 ng mL(-1), n=5) and the enrichment factor of 192 and 188 were achieved for ofloxacin and lomefloxacin respectively. Finally, the method was successfully applied to the extraction and preconcentration of these drugs in biological (plasma and urine) samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. 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...

  4. Field Emission from Multiwalled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Sveningsson, M.; Jönsson, M.; Nerushev, O.; Rohmund, F.; Campbell, E. E. B.

    2002-10-01

    Films of multi-walled carbon nanotubes are very efficient cathodes for field emission devices. Films are grown by thermal chemical vapour deposition on silicon substrates with iron as a catalyst particle. Different types of films are investigated: vertically aligned MWNT with clean and coated nanotube sidewalls. SEM, TEM and Raman spectroscopy has been used in order to determine the structure of the different films. The results show that the aligned MWNT films have excellent field emission properties with high emission current densities and low turn-on and threshold fields. They also show that the presence of a surface coating with amorphous carbon has no impact on the efficiency of the field emission. The current density as a function of applied electric field (on multiple cycles) is reproducible up to a value of 1 mA/cm2. Exceeding this value leads to light emission from the carbon nanotube film at the investigated spot. Spectral measurements of this light shows a purely blackbody radiation effect with a temperature around 1550 K for the onset current density but temperatures over 2000 K are also seen for higher current densities. In addition, there is a strong correlation between the light intensity and the current density.

  5. Multi-walled carbon nanotubes in aqueous phytic acid for enhancing biosensor

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoyu; Miao, Yun; Ye, Pingping; Wen, Ying; Yang, Haifeng

    2014-04-01

    The poor dispersion of carbon based nanomaterials without strong acid pretreatment in aqueous solution is a fundamental problem, limiting its applications in biology-related fields. A good dispersion of multi-walled carbon nanotubes (MWCNTs) in water was realized by 50 wt.% phytic acid (PA) solution. As an application case, the PA-MWCNTs dispersion in aqueous solution was used for the immobilization of horseradish peroxidase (HRP) and its direct electrochemistry was realized. The constructed biosensor has a sound limit of detection, wide linear range, and high affinity for hydrogen peroxide (H2O2) as well as being free from interference of co-existing electro-active species.

  6. Processing route to disentangle multi-walled carbon nanotube towards ceramic composite.

    PubMed

    Belmonte, M; Vallés, C; Maser, W K; Benito, A M; Martinez, M T; Miranzo, P; Osendi, M I

    2009-10-01

    Multi-walled carbon nanotubes were highly aggregated into ropes after their synthesis by chemical vapour deposition and, therefore, two different methods for disentangling the bundles of nanotubes were studied. One method compared the use of mild and vigorous mechanical treatments in ethanol and the other one employed dispersants in aqueous media. For comparison purposes and according to their different exfoliating behaviour, sodium dodecyl sulphate and gum arabic were selected as dispersants. The results evidenced that mechanical sonication was insufficient for disentangling the ropes, whereas, the combined action of mild sonication in an ultrasonic bath with the addition of gum arabic to an aqueous suspension containing nanotubes improved the exfoliating performance. Stable suspensions of unbundled multi-walled carbon nanotubes were obtained adding only 0.05 wt% of gum arabic with a dispersant/MWNTs concentration ratio of 0.25. These values corresponded to a reduction in the dispersant concentration between 1 to 2 orders of magnitude compared to those commonly employed. In addition, a processing route for manufacturing dense and homogenous silicon nitride composites using spark plasma sintering with 1.8 vol% of multi-walled carbon nanotubes almost free of organics was developed without nanotubes degradation and aggregation.

  7. Nanomechanical Behavior of Multi-Walled Carbon Nanotubes Particulate Reinforced Aluminum Nanocomposites Prepared by Ball Milling

    PubMed Central

    Ostovan, Farhad; Matori, Khamirul Amin; Toozandehjani, Meysam; Oskoueian, Arshin; Yusoff, Hamdan Mohamed; Yunus, Robiah; Mohamed Ariff, Azmah Hanim

    2016-01-01

    The nanomechanical properties of carbon nanotubes particulate-reinforced aluminum matrix nanocomposites (Al-CNTs) have been characterized using nanoindentation. Bulk nanocomposite specimens containing 2 wt % multiwalled CNTs (MWCNTs) were synthesized by a combination of ball milling and powder metallurgy route. It has been tried to understand the correlation between microstructural evolution particularly carbon nanotubes (CNTs) dispersion during milling and mechanical properties of Al-2 wt % nanocomposites. Maximum enhancement of +23% and +44% has been found in Young’s modulus and hardness respectively, owing to well homogenous dispersion of CNTs within the aluminum matrix at longer milling time. PMID:28773261

  8. Nanomechanical Behavior of Multi-Walled Carbon Nanotubes Particulate Reinforced Aluminum Nanocomposites Prepared by Ball Milling.

    PubMed

    Ostovan, Farhad; Matori, Khamirul Amin; Toozandehjani, Meysam; Oskoueian, Arshin; Yusoff, Hamdan Mohamed; Yunus, Robiah; Mohamed Ariff, Azmah Hanim

    2016-02-26

    The nanomechanical properties of carbon nanotubes particulate-reinforced aluminum matrix nanocomposites (Al-CNTs) have been characterized using nanoindentation. Bulk nanocomposite specimens containing 2 wt % multiwalled CNTs (MWCNTs) were synthesized by a combination of ball milling and powder metallurgy route. It has been tried to understand the correlation between microstructural evolution particularly carbon nanotubes (CNTs) dispersion during milling and mechanical properties of Al-2 wt % nanocomposites. Maximum enhancement of +23% and +44% has been found in Young's modulus and hardness respectively, owing to well homogenous dispersion of CNTs within the aluminum matrix at longer milling time.

  9. 75 FR 5546 - Proposed Significant New Use Rule for Multi-walled Carbon Nanotubes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-03

    ... AGENCY 40 CFR Part 721 RIN 2070-AB27 Proposed Significant New Use Rule for Multi-walled Carbon Nanotubes... chemical substance identified generically as multi-walled ] carbon nanotubes (P-08-199). This action would... commencing the manufacture, import, or processing of the specific multi-walled carbon nanotubes identified by...

  10. 76 FR 26186 - Multi-Walled Carbon Nanotubes; Significant New Use Rule

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-06

    ... AGENCY 40 CFR Parts 9 and 721 RIN 2070-AB27 Multi-Walled Carbon Nanotubes; Significant New Use Rule... substance identified generically as multi-walled carbon nanotubes (MWCNT) which was the subject of... chemical substance identified generically (due to confidentiality claims) as multi-walled carbon nanotubes...

  11. 40 CFR 721.10279 - Multi-walled carbon nanotubes (generic) (P-10-246).

    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 § 721.10279 Multi-walled carbon nanotubes (generic) (P-10-246). (a) Chemical... as multi-walled carbon nanotubes (PMN P-10-246) is subject to reporting under this section for the...

  12. 40 CFR 721.10279 - Multi-walled carbon nanotubes (generic) (P-10-246).

    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 § 721.10279 Multi-walled carbon nanotubes (generic) (P-10-246). (a) Chemical... as multi-walled carbon nanotubes (PMN P-10-246) is subject to reporting under this section for the...

  13. 40 CFR 721.10276 - Multi-walled carbon nanotubes (generic) (P-10-39).

    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 § 721.10276 Multi-walled carbon nanotubes (generic) (P-10-39). (a) Chemical... as multi-walled carbon nanotubes (PMN P-10-39) is subject to reporting under this section for the...

  14. 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...

  15. 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...

  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 721.10183 - 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...

  18. 40 CFR 721.10671 - 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 § 721.10671 Multi-walled carbon nanotubes (generic). (a) Chemical substances... multi-walled carbon nanotubes (PMNs P-09-198 and P-09-199) are subject to reporting under this section...

  19. 40 CFR 721.10703 - 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 § 721.10703 Multi-walled carbon nanotubes (generic). (a) Chemical substances... multi-walled carbon nanotubes (PMNs P-12-416, P-12-417, P-12-418, and P-12-419) are subject to reporting...

  20. 40 CFR 721.10663 - Functionalized 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 Functionalized multi-walled carbon... 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 40 CFR 721.10663 - Functionalized 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 Functionalized multi-walled carbon... 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...

  6. Photothermal therapy of melanoma tumor using multiwalled carbon nanotubes

    PubMed Central

    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/cm2) 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. PMID:28684911

  7. 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.

  8. Study of the alignment of multiwalled carbon nanotubes using dielectrophoresis

    NASA Astrophysics Data System (ADS)

    Zhang, Chen; Breedon, M.; Wlodarski, W.; Kalantar-zadeh, K.

    2007-12-01

    Presented is the dielectrophoresis of multiwalled carbon nanotubes on piezoelectric substrates patterned with gold inter digitated electrodes. An alternating current oscillating at frequencies of 1 kHz and 150 kHz at a peak-to-peak (p-p) voltage of 1V to 10V was applied to the electrodes, aligning carbon nanotubes suspended in droplets of isopropyl alcohol (IPA). The carbon nanotubes were suspended in a dielectric medium (IPA) at a concentration of approx 0.1 mg/mL and stabilized with sodium citrate (0.02 mg/ml). Sonicated for two hours and spun down in a centrifuge for 30 minutes at 4500 rpm. The carbon nanotubes used in the DEP experimentation were multiwalled carbon nanotubes with aspect ratios of approx 100:1.

  9. Carbon nanoparticle-modified multi-wall carbon nanotubes with fast adsorption kinetics for water treatment

    NASA Astrophysics Data System (ADS)

    Wang, Guan; Ren, Wei; Tan, Hui Ru; Liu, Ye

    2017-02-01

    Carbon nanoparticle-modified multi-wall carbon nanotubes were prepared using a dehydration of carbohydrate compound method. The structural change was characterized by transmission electron microscopy, Raman spectroscopy, and Brunauer, Emmett and Teller measurement. Fast adsorption kinetics was observed for multi-wall carbon nanotubes with modification, as demonstrated by the adsorption of the model compound methylene blue. This work provides a novel facile engineering strategy to equip multi-wall carbon nanotubes with fast adsorption kinetics, which is promising for efficient water purification.

  10. 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

  11. Growth of apatite on chitosan-multiwall carbon nanotube composite membranes

    NASA Astrophysics Data System (ADS)

    Yang, Jun; Yao, Zhiwen; Tang, Changyu; Darvell, B. W.; Zhang, Hualin; Pan, Lingzhan; Liu, Jingsong; Chen, Zhiqing

    2009-07-01

    Bioactive membranes for guided tissue regeneration would be of value for periodontal therapy. Chitosan-multiwall carbon nanotube (CS-MWNT) composites were treated to deposit nanoscopic apatite for MWNT proportions of 0-4 mass%. Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction were used for characterization. Apatite was formed on the CS-MWNT composites at low MWNT concentrations, but the dispersion of the MWNT affects the crystallite size and the Ca/P molar ratio of the composite. The smallest crystallite size was 9 nm at 1 mass% MWNT.

  12. Structural and electrical properties of functionalized multiwalled carbon nanotube/epoxy composite

    SciTech Connect

    Gantayat, S., E-mail: subhra-gantayat@rediffmail.com; Rout, D.; Swain, S. K.

    2016-05-23

    The effect of the functionalization of multiwalled carbon nanotube on the structure and electrical properties of composites was investigated. Samples based on epoxy resin with different weight percentage of MWCNTs were prepared and characterized. The interaction between MWCNT & epoxy resin was noticed by Fourier transform infrared spectroscopy (FTIR). The structure of functionalized multiwalled carbon nanotube (f-MWCNT) reinforced epoxy composite was studied by field emission scanning electron microscope (FESEM). The dispersion of f-MWCNT in epoxy resin was evidenced by high resolution transmission electron microscope (HRTEM). Electrical properties of epoxy/f-MWCNT nanocomposites were measured & the result indicated that the conductivity increasedmore » with increasing concentration of f-MWCNTs.« less

  13. Polypyrrole Nanocomposites Reinforced with Multi-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Bhalerao, Nikita

    The performance of conducting polymer/carbon nanotube nanocomposites have attracted much attention because of the enhanced electrical, optical, mechanical and thermal properties. They are promising electrode materials for high power supercapacitor because of the large pseudocapacitance offered by the conducting polymers and excellent mechanical properties of carbon nanotubes. In this work, a simple approach to synthesize nanocomposite of multi-walled carbon nanotubes (MWCNTs) and polypyrrole (PPy) is described. Polypyrrole vapors were chemically deposited on the surface of oxidized multi-walled carbon nanotubes. The morphology and structure of the nanocomposite was characterized by SEM and FT-IR. The results suggested that polypyrrole coated the MWCNTs uniformly. Thermal gravimetric analysis was performed to study the effect of the reinforcement of MWCNTs in polypyrrole matrix. It was found that MWCNTs increased the thermal stability of polypyrrole significantly. Cyclic voltammetry was used to study the electrochemical charge storage properties of the nanocomposite towards the application as electrode material for supercapacitors.

  14. Mechanisms for catalytic CVD growth of multiwalled carbon nanotubes.

    PubMed

    Bajwa, Navdeep; Li, Xuesong; Ajayan, Pulickel M; Vajtai, Robert

    2008-11-01

    Carbon nanotubes possess unique properties that make them potentially ideal materials for various technological applications. However, a basic growth mechanism explaining the way metallic atoms interact with carbon to nucleate, grow and heal CNTs still needs to be understood. In this review paper we describe the mechanisms of catalytic chemical vapor deposition growth of multi-walled carbon nanotubes and carbon nanofibers, the role of various parameters that govern their growth kinetics and the knowledge added to singlewalled nanotube growth. We also examine future strategies needed to reveal complete knowledge of the growth mechanisms of carbon nanotubes.

  15. 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.

  16. Characterization of functionalized multi-walled carbon nanotubes in pre-vulcanized natural rubber latex

    NASA Astrophysics Data System (ADS)

    Aziz, Azira Abd; Ismail, Nik Intan Nik; Che Su, M. S.; Rusop, M.

    2012-06-01

    A novel natural rubber/multi-walled carbon nanotubes (NR/MWCNTs) nanocomposite is developed by combining self-assembly technique. Natural rubber composites containing carboxylated multiwalled carbon nanotubes dispersed with sodium dodecyl sulfate generated in situ by the sol-gel process are investigated. The functionalization of CNTs was carried out by diazonium salt methodology in acid medium. The sol-gel processing is conducted in order to obtain a good dispersion of the inorganic particles. In each case, the different content of functionalized carbon nanotubes was mixed with natural rubber latex. Results from FESEM, FTIR and Raman analyses indicated that homogeneous dispersion of CNT throughout NR matrix with strong interfacial adhesion between oxidized CNT and the matrix are responsible for the considerable enhancement on the properties of the composite. The NR/MWCNTs have great potential to manufacture products with high mechanical performances.

  17. Strengthening of semicoke based carbon composites through multi-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kumar, Rajeev; Dhakate, Sanjay R.; Mathur, R. B.

    2014-06-01

    The present investigation explored the possibility of developing carbon composites using semicoke as matrix precursor and multi-walled carbon nanotubes (MWCNTs) as reinforcement. The different weight fraction of MWCNTs was incorporated in semicoke-based composites, and these composites were heat treated at 1,000, 1,400 and 2,500 °C. The MWCNTs carbon composite was characterized for electrical, thermal and mechanical properties. It was observed that the bulk density of composites with 1 wt% of MWCNTs was 1.92 g/cc, whereas without nanotubes it was 1.87 g/cc. The bending strength of carbonized composites was increased by 78 % and that of graphitized ones by 69 % at 1 wt% of MWCNTs. This value of bending strength was three times higher than that of conventional graphite. The electrical and thermal conductivity increased by 12 and 33 %, respectively. The Raman spectroscopic studies showed that intensity ratio of D and G band (ID)/(IG) ratio minimum deflects the lower level of defects and higher degree of graphitization in carbon composites at 1 wt% of MWCNTs. This demonstrates that in case of MWCNTs, semicoke-based carbon composites with 1 wt% of MWCNTs were sufficient for strengthening carbon composites, if MWCNTs were well dispersed in semicoke.

  18. 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

  19. 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.

  20. Multiwalled carbon nanotube supported PtRu for the anode of direct methanol fuel cells.

    PubMed

    Prabhuram, J; Zhao, T S; Tang, Z K; Chen, R; Liang, Z X

    2006-03-23

    The activity of the methanol oxidation reaction of a multiwalled carbon nanotube (MWCNT)-supported PtRu catalyst was investigated and compared with the Vulcan XC-72 carbon-supported catalyst. The PtRu nanoparticles with 1:1 and 7:3 atomic ratios (with similar PtRu loadings and morphological structures) were deposited both on the MWCNTs and on the carbon. Cyclicvoltammetry results demonstrated that the MWCNT-supported PtRu catalyst exhibited a higher mass activity (mA mg(-1) of PtRu) for the methanol oxidation reaction than the carbon-supported PtRu under the condition that both catalysts possess more or less the same PtRu loadings, particle sizes, dispersions, and electrochemical surface area. The direct methanol fuel cell performance test data showed that MWCNT-supported PtRu catalysts yielded about 35-39% higher power densities than the carbon-supported PtRu.

  1. Fabrication of multi-walled carbon nanotubes-aluminum matrix composite by powder metallurgy technique

    NASA Astrophysics Data System (ADS)

    Bunakov, N. A.; Kozlov, D. V.; Golovanov, V. N.; Klimov, E. S.; Grebchuk, E. E.; Efimov, M. S.; Kostishko, B. B.

    We report on fabrication of an aluminum matrix composite containing multi-walled carbon nanotubes (MWCNTs) produced by MOCVD method and functionalized via acid treatment by a H2SO4/HNO3 mixture. Specimens were prepared by spark plasma sintering (SPS) of the aluminum powder with different amounts of functionalized MWCNTs (FMWCNTs) in the range of 0.1-1 wt.%. We studied the effect of FMWCNTs amount on microstructure and mechanical properties of composites. It is shown that functionalization allows homogeneous dispersing of the MWCNTs in Al powder. The maximal increase in micro-hardness and tensile strength is registered at 0.1 wt.%.

  2. Quantitative stability analyses of multiwall carbon nanotube nanofluids following water/ice phase change cycling

    NASA Astrophysics Data System (ADS)

    Ivall, Jason; Langlois-Rahme, Gabriel; Coulombe, Sylvain; Servio, Phillip

    2017-02-01

    Multiwall carbon nanotube nanofluids are regularly investigated for phase change enhancement between liquid and solid states owing to their improved heat transfer properties. The potential applications are numerous, the most notable being latent heat thermal energy storage, but the success of all nanofluid-assisted technologies hinges greatly on the ability of nanoparticles to remain stably dispersed after repeated phase change cycles. In this report, the stability of aqueous nanofluids made from oxygen-functionalized multiwall carbon nanotubes (f-MWCNTs) was profiled over the course of 20 freeze/thaw cycles. Sonication was used after each cycle to re-disperse clusters formed from the crystallization process. This study offers a quantitative evaluation of f-MWCNT-nanofluid stability as a result of phase change through optical characterization of concentration and particle size. It also provides insight into the integrity of the surface functionalities through zeta potential and XPS analyses. Concentration and particle size measurements showed moderate and consistent recoverability of f-MWCNT dispersion following ultrasonication. XPS measurements of solid-state MWCNTs exposed to freeze/thaw cycling in water, and zeta potential analyses of the nanofluids indicate that the surface oxygen content is preserved throughout phase change and over repeated cycles. These results suggest a resilience of oxygen-functionalized MWCNTs to the freezing and thawing of water, which is ideal for their utilization as phase change enhancers.

  3. 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.

  4. Absorption and Reflectance Spectra of Microwave Radiation by an Epoxy Resin Composite with Multi-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Komarov, F. F.; Milchanin, O. V.; Parfimovich, I. D.; Grinchenko, M. V.; Parhomenko, I. N.; Tkachev, A. G.; Bychanok, D. S.

    2017-09-01

    A procedure for dispersing multi-walled carbon nanotubes in the two-component polymer SpeciFix-20 (epoxy resin + hardener) using combined hydromechanical and ultrasonic mixing was developed. New composites with carbon nanotubes were produced. Their structures and optical and electrophysical characteristics were studied. The propagation of microwave radiation (26-38 GHz) in experimental composite samples was investigated. It was shown that the strong absorption of the composites appeared only with significant additions of multi-walled carbon nanotubes and was caused by the resulting electrical conductivity of the composites. A size effect of the additive on the optical characteristics of the produced composites was established. Equal absorption coefficients for microwave radiation could be achieved by using a smaller amount of carbon nanotubes with smaller diameters and greater specific surface areas in the composite.

  5. 77 FR 39236 - Nanomaterial Case Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-02

    ... AGENCY Nanomaterial Case Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether... Study: A Comparison of Multiwalled Carbon Nanotubes and Decabromodiphenyl Ether Flame-Retardant Coatings... nanotubes (MWCNT); rather, it aims to identify what is known and unknown about MWCNT to support future...

  6. Correlating electrical resistance to growth conditions for multiwalled carbon nanotubes

    SciTech Connect

    Lan, Chun; Amama, Placidus B.; Fisher, Timothy S.; Reifenberger, Ronald G.

    2007-08-27

    A correlation between growth temperature and electrical resistance of multiwalled carbon nanotubes (MWNTs) has been established by measuring the resistance of individual MWNTs grown by microwave plasma-enhanced chemical vapor deposition (PECVD) at 800, 900, and 950 deg. C. The lowest resistances were obtained mainly from MWNTs grown at 900 deg. C. The MWNT resistance is larger on average at lower (800 deg. C) and higher (950 deg. C) growth temperatures. The resistance of MWNTs correlated well with other MWNT quality indices obtained from Raman spectra. This study identifies a temperature window for growing higher-quality MWNTs with fewer defects and lower resistance by PECVD.

  7. Multi-walled carbon nanotubes induce T lymphocyte apoptosis.

    PubMed

    Bottini, Massimo; Bruckner, Shane; Nika, Konstantina; Bottini, Nunzio; Bellucci, Stefano; Magrini, Andrea; Bergamaschi, Antonio; Mustelin, Tomas

    2006-01-05

    Carbon nanotubes are a man-made form of carbon that did not exist in our environment until very recently. Due to their unique chemical, physical, optical, and magnetic properties, carbon nanotubes have found many uses in industrial products and in the field of nanotechnology, including in nanomedicine. However, very little is yet known about the toxicity of carbon nanotubes. Here, we compare the toxicity of pristine and oxidized multi-walled carbon nanotubes on human T cells and find that the latter are more toxic and induce massive loss of cell viability through programmed cell death at doses of 400 microg/ml, which corresponds to approximately 10 million carbon nanotubes per cell. Pristine, hydrophobic, carbon nanotubes were less toxic and a 10-fold lower concentration of either carbon nanotube type were not nearly as toxic. Our results suggest that carbon nanotubes indeed can be very toxic at sufficiently high concentrations and that careful toxicity studies need to be undertaken particularly in conjunction with nanomedical applications of carbon nanotubes.

  8. 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).

  9. 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.

  10. Bacterial remediation from effluent containing multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lemes, A. P.; Cordi, L.; Santos, A.; Durán, N.

    2011-07-01

    Multi-wall carbon nanotubes (MWCNT) were functionalized with functional groups containing oxygen, mainly carboxylic groups (-COOH), through reaction with a mixture of H2SO4/HNO3 (3:1 v/v). The oxidized multi-wall carbon nanotubes (MWCNTOOH) were used to prepare an effluent, 2 mg L-1 in a saline solution of NaCl (0.9%), to study of remediation of MWCNTOOH in aqueous suspension by utilization of Escherichia coli. The suspensions of E. coli (4.5 × 105 CFU mL-1 and 4.5 × 108 CFU mL-1) in test tubes with MWCNTOOH effluent caused the precipitation of a large amount of MWCNTOOH and supernatant clearing. The scanning electron microscopy (SEM) analysis of the precipitate and supernatant showed the adhesion and interlace of MWCNTOOH in bacteria surface. Although the precipitate consist of a large quantity of MWCNTOOH and bacteria, it was verified their presence in the supernatant. The spread plate technique showed that MWCNTOOH caused no cellular death of E. coli in the supernatant.

  11. Rheology, Morphology and Temperature Dependency of Nanotube Networks in Polycarbonate/Multiwalled Carbon Nanotube Composites

    SciTech Connect

    Abbasi, Samaneh; Carreau, Pierre J.; Derdouri, Abdessalem

    2008-07-07

    We present several issues related to the state of dispersion and rheological behavior of polycarbonate/multiwalled carbon nanotube (MWCNT) composites. The composites were prepared by diluting a commercial masterbatch containing 15 wt% nanotubes using optimized melt-mixing conditions. The state of dispersion was then analyzed by scanning and transmission electron microscopy (SEM, TEM). Rheological characterization was also used to assess the final morphology. Further, it was found that the rheological percolation threshold decreased significantly with increasing temperature and finally reached a constant value. This is described in terms of the Brownian motion, which increases with temperature. However, by increasing the nanotube content, the temperature effects on the complex viscosity at low frequency decreased significantly. Finally, the percolation thresholds were found to be approximately equal to 0.3 and 2 wt% for rheological and electrical conductivity measurements, respectively.

  12. Structure-property relationship in polyethylene reinforced by polyethylene-grafted multi-walled carbon nanotubes.

    PubMed

    Causin, Valerio; Yang, Bing-Xing; Marega, Carla; Goh, Suat Hong; Marigo, Antonio

    2008-04-01

    Polyethylene-grafted multiwalled carbon nanotubes (PE-g-MWNT) were used to reinforce polyethylene (PE). The nanocomposites possessed not only improved stiffness and strength, but also increased ductility and toughness. The effects on the structure and morphology of composites due to pristine multiwalled carbon nanotubes (MWNT) and PE-g-MWNT were studied and compared using small angle X-ray scattering (SAXS), wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The SAXS long period, crystalline layer thickness and crystallinity of polymer lamellar stacks were found to decrease significantly in MWNT composites, while the decreases were much smaller in PE-g-MWNT composites. PE-g-MWNT allowed a more efficient and unhindered crystallization at a lamellar level, while MWNT disrupted the order of lamellar stacks, probably because of their tendency to aggregate. The SAXS crystallinity and the mechanical properties of the composites showed similar trends as a function of MWNT content. This suggested that the improvement of the interfacial strength between polymer and carbon nanotubes was a result of synergistic effects of better dispersion of the filler, better stress transfer, due to the grafting of polymer and MWNT, and the nucleation of a crystalline phase around MWNT. The latter effect was confirmed by measurements of kinetics of non-isothermal crystallization.

  13. Efficient and facile one pot carboxylation of multiwalled carbon nanotubes by using oxidation with ozone under mild conditions

    NASA Astrophysics Data System (ADS)

    Naeimi, Hossein; Mohajeri, Ali; Moradi, Leila; Rashidi, Ali Morad

    2009-11-01

    In this study, oxidation of carbon nanotubes with ozone in the presence of hydrogen peroxide was investigated. The reaction was performed under clean and mild conditions and oxidized products with high concentration of oxygenated groups were yielded. The reaction products were characterized with attenuated total reflectance (ATR), Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffractometry (XRD), back titration, X-ray photoelectron spectroscopy (XPS) and the dispersion behavior of the oxidized multiwalled carbon nanotubes (MWCNTs) was also studied. The results confirmed the presence of high concentrations of oxidative groups on the carbon nanotubes (CNTs) treated by the method of the present work.

  14. Improvement of Cementitious Binders by Multi-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kowald, T.; Trettin, R.

    To improve the mechanical properties of building materials carbon nanotubes (CNTs) were incorporated into normal concretes, high and ultra-high performance concretes as well as into model systems. Besides their outstanding mechanical properties CNTs are a very promising reinforcement material for composites because of their high aspect ratio, high resistance to corrosion and low specific weight. Multi-walled carbon nanotubes (MWCNTs) showed an influence on the hydration of binders and their macro- and microscopic mechanical properties. The effects of the nanostructures on the hydration, the composition and the micro- and nanostructure of the composite were investigated by the use of the in situ x-ray powder diffraction, isothermal calorimetric measurements, an ultrasonic method, imaging methods and the grid nanoindentation technique. The results show that the MWCNTs influence the hydration, the microstructure and are leading to improved mechanical properties of the composite. This presentation shows thermal analysis and porosimetry data of samples prepared with MWCNTs.

  15. 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.

  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. 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

  18. 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.

  19. Frictional Reduction with Partially Exfoliated Multi-Walled Carbon Nanotubes as Water-Based Lubricant Additives.

    PubMed

    Sun, Xinghui; Zhao, Min; Han, Bai; Kang, Hongjun; Fan, Zhimin; Liu, Yuyan; Umar, Ahmad; Guo, Zhanhu

    2018-05-01

    In this work, partially exfoliated multi-walled carbon nanotubes (Px-CNTs) were prepared by oxidizing multi-walled carbon nanotubes (MWCNTs) and applied into water-based lubricant as a kind of new additives, resulting in an outstanding anti-friction effect. The Px-CNTs have the structures of both MWCNTs and graphene oxide nanoribbons (GONRs). The special structure could prevent aggregation in water-based lubricant and reduce friction effectively. At the same time, Px-CNTs generate both sliding and rolling friction like MWCNTs and GONRs simultaneously. The friction force of Px-CNTs tended to go up after declining with increasing its loading, suggesting the existence of optimum additive amount of additions. Compared with water, water with 0.5 wt% Px-CNTs further reduced the friction force up to 66.4%. Compared with CNTs-COOH and GONRs dispersed in water via a similar method, Px-CNTs in water displays remarkable friction characteristic, suggesting that the friction force of water with 0.5 wt% Px-CNTs is decreased by 19.82% and 13.82% compared with water with 0.3 wt% MWCNTs and GONRs.

  20. Amperometric sensor based on ferrocene-modified multiwalled carbon nanotube nanocomposites as electron mediator for the determination of glucose.

    PubMed

    Qiu, Jian-Ding; Zhou, Wen-Mei; Guo, Jin; Wang, Rui; Liang, Ru-Ping

    2009-02-15

    A kind of nanocomposite with good dispersion in water was prepared through covalent adsorption of ferrocenecarboxaldehyde on multiwalled carbon nanotubes (MWNTs) for electrical communication between glucose oxidase (GOD) and electrode. The ferrocene-modified multiwalled carbon nanotube nanocomposites (MWNTs-Fc) could be conveniently cast on electrode surfaces. With the aid of chitosan, GOD was then immobilized on the nanostructure film to form a reagentless amperometric sensor for glucose determination. FTIR spectra and cyclic voltammetry were used to characterize the nanocomposites. The presence of both ferrocene as mediator of electron transfer and MWNTs as conductor enhanced greatly the enzymatic response to the oxidation of glucose. The novel biosensor exhibited a fast response toward glucose with a detection limit of 3.0 x 10(-6) mol/L and the linear range extended up to 3.8 x 10(-3) mol/L.

  1. Dispergation and modification of multi-walled carbon nanotubes in aqueous solution

    NASA Astrophysics Data System (ADS)

    Qu, Chunlai; Cheng, Fang; Su, Hui; Zhao, Yang

    2016-11-01

    Multi-walled carbon nanotubes (MWCNTs) are widely applied in development of composite materials. However, their properties are directly influenced by the degree of uniformity of dispersion of MWCNTs in the material's matrix. In this paper, the dispersing of raw MWCNTs (R-MWCNTs) and decorated MWCNTs (D-MWCNTs) was studied in aqueous solution. The D-MWCNTs were obtained by chemical modification method by treatment of initial MWCNTs with the mixture of concentrated nitric and sulfuric acids (3: 1 vol/vol). To achieve a good dispersion of the MWCNTs, a method utilizing ultrasonic processing and surfactant (polyvinylpyrrolidone, PVP) was employed. MWCNTs were characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The prepared MWCNTs suspensions were investigated by UV spectroscopy, zeta potential measurements, surface tension and transmission electron microscopy (TEM). The D-MWCNTs have better dispersibility in aqueous solution; this attributed to the functional groups formed on their surface during chemical modification. The PVP surfactant in a certain concentration of 0.6 g/L has the maximum dispersing effect on MWCNTs in aqueous solution, the optimum concentration ratio of PVP and MWCNTs was 3: 1.

  2. Electrical conductivity of polypropylene fibers with dispersed carbon fillers

    NASA Astrophysics Data System (ADS)

    Moskalyuk, O. A.; Aleshin, A. N.; Tsobkallo, E. S.; Krestinin, A. V.; Yudin, V. E.

    2012-10-01

    Polypropylene fibers with fillers in the form of carbon nanoparticles of four types (technical carbon, graphitized carbon nanofibers, multi-walled carbon nanotubes, and single-walled carbon nanotubes) have been synthesized. For all types of fillers, the electrical conductivity of the fibers has been measured as a function of the concentration of nanoparticles and the percolation thresholds have been determined. A correlation between the nanoparticle concentration and the electrical conductivity of the percolation cluster at the percolation threshold with the cross section, the axial ratio, and the shape of the nanoparticles dispersed in the polymer matrix has been discussed. The dependence of the electrical conductivity of the composite material with carbon nanofibers on the temperature has been measured.

  3. Electrical transport properties of individual disordered multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Tsai, Meng-Yen; Yu, Chung-Yi; Yang, Chien-Hsin; Tai, Nyan-Hwa; Perng, Tsong-Pyng; Tu, Chien-Ming; Khan, Zishan Husain; Liao, Yang-Chung; Chi, Cheng Chung

    2006-11-01

    The electrical transport properties of individual disordered multiwalled carbon nanotubes (MWCNTs), synthesized with the floating catalyst method, have been investigated. The resistivity of such disordered MWCNTs shows T1/2 dependence over a temperature range of 4.2-263K. The experimental finding can be interpreted in terms of Al'tshuler-Aronov model [Solid State Commun. 30, 115 (1979); Sov. Phys. JETP 50, 968 (1979); Pis'ma. Zh. Eksp. Teor. Fiz. 27, 700 (1978)], in which strong electron-electron interaction leads to a Coulomb gap in the density of electronic states at the Fermi level. Such a wide fitting range of temperature for T1/2 dependence has never been reported for other materials, implying an extremely short carrier scattering time of the order of femtoseconds.

  4. 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

  5. Conductance in multiwall carbon nanotubes and semiconductor nanowires

    NASA Astrophysics Data System (ADS)

    Dayen, J.-F.; Wade, T. L.; Konczykowski, M.; Wegrowe, J.-E.; Hoffer, X.

    2005-08-01

    Electronic transport in an ensemble of multiwall carbon nanotubes and semiconductor nanowires was compared. The nanotubes and nanowires are obtained by template synthesis and are contacted in a current perpendicular to the plane geometry by using different methods. In all cases, the nonohmic behavior of the conductance, the so-called zero-bias anomaly, shows a temperature dependence that scales with the voltage dependence. This robust scaling law describes the conductance G(V,T) by a single coefficient α . A universal behavior as a function of α is found for all samples. Magnetoconductance measurements furthermore show that the conduction regime is weak localization. The observed behavior can be understood in terms of the Coulomb blockade theory, providing that a single tunnel barrier is present. This hypothetical tunnel barrier would have a resistance of the order of 2500Ω and a typical energy of about 40meV for all samples.

  6. 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.

  7. 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.

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

    PubMed

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

    2015-09-01

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

  9. 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.

  10. Synthesis of multiwalled carbon nanotubes on fly ash derived catalysts.

    PubMed

    Dunens, Oscar M; MacKenzie, Kieran J; Harris, Andrew T

    2009-10-15

    Carbon nanotubes (CNTs) are an allotrope of carbon with unique properties that make them potentially useful in a vast range of applications. However, CNTs are predominantly produced using expensive and/or nonrecyclable catalyst supports, e.g., mesoporous silica and alumina. In this work, coal combustion fly ash, a bulk waste product with limited uses, was impregnated with iron nitrate and successfully used as a substrate to produce industrial grade multiwalled carbon nanotubes (MWNTs) by fluidized bed chemical vapor deposition. CNTs were analyzed using thermogravimetric analysis, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The most successful catalyst trialed at 650 degrees C using ethylene as a carbon source was a 5 wt % Fe fly ash catalyst, which produced a CNT yield in respect to metal loading of approximately 82.5%. The MWNTs had outer diameters of between 12 and 20 nm with a reasonable degree of wall graphitization (I(G)/I(D) of 1.17). Advantages of utilizing fly ash as a catalyst support are its availability at low cost at the megaton scale, its high thermal stability, and suitability for use in industrial fluidized bed reactors. Potential applications for the fly ash produced CNTs include use in composite materials.

  11. 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.

  12. 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.

  13. Charge transport in a single superconducting tin nanowire encapsulated in a multiwalled carbon nanotube.

    PubMed

    Tombros, Nikolaos; Buit, Luuk; Arfaoui, Imad; Tsoufis, Theodoros; Gournis, Dimitrios; Trikalitis, Pantelis N; van der Molen, Sense Jan; Rudolf, Petra; van Wees, Bart J

    2008-09-01

    The charge transport properties of single superconducting tin nanowires encapsulated by multiwalled carbon nanotubes have been investigated by multiprobe measurements. The multiwalled carbon nanotube protects the tin nanowire from oxidation and shape fragmentation and therefore allows us to investigate the electronic properties of stable wires with diameters as small as 25 nm. The transparency of the contact between the Ti/Au electrode and nanowire can be tuned by argon ion etching the multiwalled nanotube. Application of a large electrical current results in local heating at the contact which in turn suppresses superconductivity.

  14. Properties and electrochemical characteristics of boron-doped multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Tsierkezos, Nikos G.; Ritter, Uwe; Nugraha Thaha, Yudi; Krischok, Stefan; Himmerlich, Marcel; Downing, Clive

    2015-10-01

    Boron-doped multi-walled carbon nanotubes were synthesized upon decomposition of ethyl alcohol and boric acid via chemical vapor deposition. The boron-doped nanotubes were treated with hydrochloric acid and were characterized by means of scanning electron and transmission electron microscopy in conjunction with energy-dispersive X-ray spectrometry and X-ray photoelectron spectroscopy. The electrochemistry of ferrocyanide/ferricyanide on boron-doped nanotubes was studied in temperature range of 283.15-303.15 K. The findings exhibit an improvement of films' current response and kinetics of electron transfer with the rise in temperature. The kinetics for electron transfer enhances and the redox process occurs slightly more spontaneously upon acid treatment.

  15. Preparation of PVA/amino multi-walled carbon nanotubes nanocomposite microspheres for endotoxin adsorption.

    PubMed

    Zong, Wenhui; Chen, Jian; Han, Wenyan; Cheng, Guanghui; Chen, Jie; Wang, Yue; Wang, Weichao; Ou, Lailiang; Yu, Yaoting; Shen, Jie

    2018-02-01

    A novel polyvinyl alcohol-amino multi-walled carbon nanotube (PVA-AMWCNT) nanocomposite microsphere was prepared successfully for the first time and used for endotoxin removal. The resulting AMWCNT modified PVA microsphere was characterized by SEM, Raman spectrum and fluorescence image, which indicated AMWCNT was dispersed into the macropores of PVA microsphere uniformly. The PVA-AMWCNT microspheres showed better adsorption capability and faster adsorption equilibrium for endotoxin in aqueous solution when compared to the PVA microsphere with polymyxin B (PMB) as ligand. More noteworthy, the PVA based microspheres had little nonspecific adsorption in simulated serum. Therefore, PVA-AMWCNT nanocomposite microsphere with an excellent haemocompatibility has a great potential application in clinical blood purification.

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

    SciTech Connect

    Brühwiler, Paul A.; Barbezat, Michel; Necola, Adly; Kohls, Doug J.; Bunk, Oliver; Schaefer, Dale W.; Pötschke, Petra

    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 absorption 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.

  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. Multiwalled carbon nanotubes bearing 'terminal monomeric unit' for the fabrication of epinephrine imprinted polymer-based electrochemical sensor.

    PubMed

    Prasad, Bhim Bali; Prasad, Amrita; Tiwari, Mahavir Prasad; Madhuri, Rashmi

    2013-07-15

    Carbon-nanotubes play a pivotal role in molecularly imprinted polymer technology for inculcating conducting property, high surface to volume ratio, and maximum porosity in the film texture. Contrary to the non-covalent heterogeneous dispersion of pure (unmodified) multiwalled carbon nanotubes in the imprinted polymer film, the homogeneous distribution of their functionalized derivative was found more effective to augment the sensitivity of the measurement. This could be made feasible using multiwalled carbon nanotubes bearing terminal monomeric unit (termed as "CNT-mer") for the polymerization (one CNT-mer in each repeating unit). In this work, the CNT-mer entails a N-hydroxyphenyl maleimide functionality to be utilized in the chain propagation with simultaneous imprinting of epinephrine in the polymeric network. This system, when casted on the tip of a pencil graphite electrode, responded a highly sensitive and selective response for epinephrine, prevalent in aqueous and real samples at ultratrace level (linear range 0.09-5.90 ng mL(-1), limit of detection 0.02 ng mL(-1), S/N=3), without any cross-reactivity and matrix effects. The proposed sensor is advantageous in obtaining enhanced differential pulse anodic stripping voltammetric current vis-a-vis the corresponding imprinted sensor modified with randomly dispersed flocculated multiwalled carbon nanotubes bundles. While the latter might restrict the interlayer diffusion of analyte in the film, the former sensor facilitated high diffusivity with the channelized electron transport to respond higher current. The CNT-mer dispersed sensor was found to be stable and rugged against mechanical stress and can be used, after regeneration, for more than hundred consecutive experiments in clinical settings. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. 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.

  20. Immune responses of BALB/c mice to subcutaneously injected multi-walled carbon nanotubes.

    PubMed

    Meng, Jie; Yang, Man; Jia, Fumin; Xu, Zhen; Kong, Hua; Xu, Haiyan

    2011-12-01

    Carbon nanotubes have been shown to have the ability to transport therapeutic and detective reagents into cells. However, the rapid advances in new carbon nanotube-based materials and technologies have raised concerns about their safety. Such concerns require a fundamental understanding of the toxicological properties of carbon nanotubes. In particular, the use of carbon nanotubes as drug or probe delivery platforms may depend on the prevention of stimulatory side-effects to the immune system. In this study, we investigated the immunological properties of oxidized water dispersible multi-walled carbon nanotubes (MWCNTs) in healthy BALB/c mice. We injected the MWCNTs subcutaneously, and the immune responses of the mice were monitored over time. We show that the MWCNTs induce complement activation and the production of pro-inflammatory cytokines early after injection of the mice, and that the levels of complement and cytokines return to normal levels over time. With the exception of the lymph nodes, there was no obvious accumulation of MWCNTs observed in the liver, spleen, kidney, or heart. In addition, we did not observe injury in the organs or lymph nodes. Our results indicate that local, subcutaneous administration of MWCNTs induces obvious short-term immunological reactions, which can be eliminated over time.

  1. Aggregates of Chemically Functionalized Multiwalled Carbon Nanotubes as Viscosity Reducers

    PubMed Central

    Petriccione, Angelo; Zarrelli, Mauro; Antonucci, Vincenza; Giordano, Michele

    2014-01-01

    Confinement and surface effects provided by nanoparticles have been shown to produce changes in polymer molecules affecting their macroscopic viscosity. Nanoparticles may induce rearrangements in polymer conformation with an increase in free volume significantly lowering the viscosity. This phenomenon is generally attributed to the selective adsorption of the polymer high molar mass fraction onto nanoparticles surface when the polymer radius of gyration is comparable to the nanoparticles characteristic dimensions. Carbon nanotubes seem to be the ideal candidate to induce viscosity reduction of polymer due to both their high surface-to-volume ratio and their nanometric sizes, comparable to the gyration radius of polymer chains. However, the amount of nanotube in a polymer system is limited by the percolation threshold as, above this limit, the formation of a nanotubes network hinders the viscosity reduction effect. Based on these findings, we have used multiwalled carbon nanotubes MWCNT “aggregates” as viscosity reducers. Our results reveal both that the use of nanotube clusters reduce significantly the viscosity of the final system and strongly increase the nanotube limiting concentration for viscosity hindering. By using hydroxyl and carboxyl functionalized nanotubes, this effect has been rather maximized likely due to the hydrogen bridged stabilization of nanotube aggregates. PMID:28788615

  2. Turning refuse plastic into multi-walled carbon nanotube forest

    NASA Astrophysics Data System (ADS)

    Oh, Eugene; Lee, Jaegeun; Jung, Seung-Ho; Cho, Seungho; Kim, Hye-Jin; Lee, Sung-Hyun; Lee, Kun-Hong; Song, Kyong-Hwa; Choi, Chi-Hoon; Han, Do Suck

    2012-04-01

    A novel and effective method was devised for synthesizing a vertically aligned carbon nanotube (CNT) forest on a substrate using waste plastic obtained from commercially available water bottles. The advantages of the proposed method are the speed of processing and the use of waste as a raw material. A mechanism for the CNT growth was also proposed. The growth rate of the CNT forest was ~2.5 μm min-1. Transmission electron microscopy images indicated that the outer diameters of the CNTs were 20-30 nm on average. The intensity ratio of the G and D Raman bands was 1.27 for the vertically aligned CNT forest. The Raman spectrum showed that the wall graphitization of the CNTs, synthesized via the proposed method was slightly higher than that of commercially available multi-walled carbon nanotubes (MWCNTs). We expect that the proposed method can be easily adapted to the disposal of other refuse materials and applied to MWCNT production industries.

  3. Terahertz dielectric properties of multiwalled carbon nanotube/polyethylene composites

    NASA Astrophysics Data System (ADS)

    Dorozhkin, K. V.; Dunaevsky, G. E.; Sarkisov, S. Yu; Suslyaev, V. I.; Tolbanov, O. P.; Zhuravlev, V. A.; Sarkisov, Yu S.; Kuznetsov, V. L.; Moseenkov, S. I.; Semikolenova, N. V.; Zakharov, V. A.; Atuchin, V. V.

    2017-10-01

    The terahertz dielectric properties of multiwalled carbon nanotube/polyethylene (MWCNT/PE) composites prepared in different ways and with various contents of carbon nanotubes have been measured by terahertz time-domain spectroscopy. The experimental dielectric susceptibilities were modeled within effective medium approximation. The MWCNTs with average diameter of 9 nm produced by ethylene decomposition over FeCo catalyst were used in the experiments. Two types of composites were prepared by various mechanical mixing of MWCNT and polyethylene powders. The other two types of composites were fabricated employing ethylene polymerization on the MWCNTs before mechanical mixing with polyethylene powder. The samples with MWCNT concentration of 0.1, 0.5, 1 and 4 wt. % were prepared for each composite type. The measured dielectric susceptibilities were higher for composites made of nanotubes with preliminary polymerization of ethylene as compared to the composites produced by just mechanical mixing at equal concentrations of MWCNTs. It was also found that the dielectric susceptibilities of the MWCNT/PE composites can be satisfactory described within Maxwell–Garnett effective medium approximation at sufficient levels (>0.5–1 wt. %) of MWCNT contents. The obtained results confirm the possibility to produce MWCNT/PE composite materials with desired dielectric properties in terahertz range.

  4. 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.

  5. 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

    ... AGENCY 40 CFR Part 721 RIN 2070-AB27 Proposed Significant New Use Rule for Multi-walled Carbon Nanotubes... multi-walled carbon nanotubes (P-08-199). In order to address public comments, EPA is adding information...-walled carbon nanotubes as identified in Premanufacture Notice (PMN) P-08-199. EPA received several...

  6. 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.

  7. 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

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

    NASA Astrophysics Data System (ADS)

    Brown, Brian L.; Martinez, Patricia; Zakhidov, Anvar A.; Shaner, Eric A.; Lee, Mark

    2015-07-01

    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, the microwave conductance can be modeled approximately by a shunt capacitance in parallel with a frequency-independent conductance, but with no inductive contribution. 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.

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

    PubMed Central

    Shen, Daming; Chen, Donglei; 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. PMID:29201267

  10. Functionalized multiwalled carbon nanotubes as ultrasound contrast agents

    PubMed Central

    Delogu, Lucia Gemma; Vidili, Gianpaolo; Venturelli, Enrica; Ménard-Moyon, Cécilia; Zoroddu, Maria Antonietta; Pilo, Giovannantonio; Nicolussi, Paola; Ligios, Ciriaco; Bedognetti, Davide; Sgarrella, Francesco; Manetti, Roberto; Bianco, Alberto

    2012-01-01

    Ultrasonography is a fundamental diagnostic imaging tool in everyday clinical practice. Here, we are unique in describing the use of functionalized multiwalled carbon nanotubes (MWCNTs) as hyperechogenic material, suggesting their potential application as ultrasound contrast agents. Initially, we carried out a thorough investigation to assess the echogenic property of the nanotubes in vitro. We demonstrated their long-lasting ultrasound contrast properties. We also showed that ultrasound signal of functionalized MWCNTs is higher than graphene oxide, pristine MWCNTs, and functionalized single-walled CNTs. Qualitatively, the ultrasound signal of CNTs was equal to that of sulfur hexafluoride (SonoVue), a commercially available contrast agent. Then, we found that MWCNTs were highly echogenic in liver and heart through ex vivo experiments using pig as an animal model. In contrast to the majority of ultrasound contrast agents, we observed in a phantom bladder that the tubes can be visualized within a wide variety of frequencies (i.e., 5.5–10 MHz) and 12.5 MHz using tissue harmonic imaging modality. Finally, we demonstrated in vivo in the pig bladder that MWCNTs can be observed at low frequencies, which are appropriate for abdominal organs. Importantly, we did not report any toxicity of CNTs after 7 d from the injection by animal autopsy, organ histology and immunostaining, blood count, and chemical profile. Our results reveal the enormous potential of CNTs as ultrasound contrast agents, giving support for their future applications as theranostic nanoparticles, combining diagnostic and therapeutic modalities. PMID:23012426

  11. 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.

  12. Electrical properties of multiwalled carbon nanotube reinforced fused silica composites.

    PubMed

    Xiang, Changshu; Pan, Yubai; Liu, Xuejian; Shi, Xiaomei; Sun, Xingwei; Guo, Jingkun

    2006-12-01

    Multiwalled carbon nanotube (MWCNT)-fused silica composite powders were synthesized by solgel method and dense bulk composites were successfully fabricated via hot-pressing. This composite was characterized by XRD, HRTEM, and FESEM. MWCNTs in the hot-pressed composites are in their integrity observed by HRTEM. The electrical properties of MWCNT-fused silica composites were measured and analyzed. The electrical resistivity was found to decrease with the increase in the amount of the MWCNT loading in the composite. When the volume percentage of the MWCNTs increased to 5 vol%, the electrical resistivity of the composite is 24.99 omega cm, which is a decrease of twelve orders of value over that of pure fused silica matrix. The electrical resistivity further decreases to 1.742 omega. cm as the concentration of the MWCNTs increased to 10 vol%. The dielectric properties of the composites were also measured at the frequency ranging from 12.4 to 17.8 GHz (Ku band) at room temperature. The experimental results reveal that the dielectric properties are extremely sensitive to the volume percentage of the MWCNTs, and the permittivities, especially the imaginary permittivities, increase dramatically with the increase in the concentration of the MWCNTs. The improvement of dielectric properties in high frequency region mainly originates from the greatly increasing electrical properties of the composite.

  13. Multiwalled carbon nanotube (MWCNT) reinforced cellulose fibers by electrospinning.

    PubMed

    Lu, Ping; Hsieh, You-Lo

    2010-08-01

    Multiwalled carbon nanotubes (MWCNTs) were successfully incorporated in ultrafine cellulose fibers by electrospinning MWCNT-loaded cellulose acetate (CA) solutions, followed by deacetylation of CA to cellulose (cell). The mean fiber diameter reduced from 321 nm of the as-spun fibers to 257 and 228 nm of those with 0.11 and 0.55 wt % MWCNTs, respectively, and became more uniform. Hydrolysis of CA to cell further reduced the mean fiber sizes by another 8-16%. The MWCNTs were observed to be well-aligned along the fiber axes. The MWCNT/cell composite fibers had increased specific surface, from 4.27 m(2)/g to 5.07 and 7.69 m(2)/g at 0.11 and 0.55 wt % MWCNTs, respectively, and much improved water wettability. The mechanical properties of the fibers were also greatly enhanced with increased MWCNT loading levels. The fact that MWCNTs were observed in only about a third of the fibers at a very low 0.55 wt % loading suggests significantly higher tensile strength may be achieved by a further increase in MWCNT loadings.

  14. Radical scavenging reaction kinetics with multiwalled carbon nanotubes.

    PubMed

    Tsuruoka, Shuji; Matsumoto, Hidetoshi; Koyama, Kenichi; Akiba, Eiji; Yanagisawa, Takashi; Cassee, Flemming R; Saito, Naoto; Usui, Yuki; Kobayashi, Shinsuke; Porter, Dale W; Castranova, Vincent; Endo, Morinobu

    2015-03-01

    Progress in the development of carbon nanotubes (CNTs) has stimulated great interest among industries providing new applications. Meanwhile, toxicological evaluations on nanomaterials are advancing leading to a predictive exposure limit for CNTs, which implies the possibility of designing safer CNTs. To pursue safety by design, the redox potential in reactions with CNTs has been contemplated recently. However, the chemical reactivity of CNTs has not been explored kinetically, so that there is no scheme to express a redox reaction with CNTs, though it has been investigated and reported. In addition, the reactivity of CNTs is discussed with regard to impurities that consist of transition metals in CNTs, which obfuscates the contribution of CNTs to the reaction. The present work aimed at modeling CNT scavenging in aqueous solution using a kinetic approach and a simple first-order reaction scheme. The results show that CNTs follow the redox reaction assumption in a simple chemical system. As a result, the reaction with multiwalled CNTs is semi-quantitatively denoted as redox potential, which suggests that their biological reactions may also be evaluated using a redox potential scheme.

  15. Cobalt nanoparticle-assisted engineering of multiwall carbon nanotubes.

    PubMed

    Wang, Ming-Sheng; Bando, Yoshio; Rodriguez-Manzo, Julio A; Banhart, Florian; Golberg, Dmitri

    2009-09-22

    New methods of processing multiwall carbon nanotubes (CNTs) are demonstrated in experiments in the transmission electron microscope (TEM). These include precisely controllable cutting, repairing, and interconnecting of different CNTs with the assistance of an encapsulated Co particle. All processes involve the interactions between the metal and graphitic shells that are driven by combined electrical biasing [using a scanning-tunneling microscope (STM)-TEM setup] of the CNT and focused electron-beam irradiation of a Co-containing region. In particular, we present two CNT soldering processes, that is, Co-joined and Co-catalytic connections. The former process uses a Co particle as the central node to which two CNTs are covalently attached on the opposite sides, and the latter makes use of the segregation of new graphitic shells from the metal at the connecting site, resulting in CNT plumbing. We compare the mechanical robustness of both connection types by direct force measurements in the TEM using an integrated atomic force microscope (AFM) setup. They reveal a tensile strength of 4.2 and 31 GPa, respectively, thus demonstrating the superiority of the Co-catalytic connection whose strength is already comparable to standard CNTs. In addition, all connected nanotubes show metallic conduction. The developed methods could be of particular importance in future nanoelectronic device technology.

  16. Polymer-derived ceramic composite fibers with aligned pristine multiwalled carbon nanotubes.

    PubMed

    Sarkar, Sourangsu; Zou, Jianhua; Liu, Jianhua; Xu, Chengying; An, Linan; Zhai, Lei

    2010-04-01

    Polymer-derived ceramic fibers with aligned multiwalled carbon nanotubes (MWCNTs) are fabricated through the electrospinning of polyaluminasilazane solutions with well-dispersed MWCNTs followed by pyrolysis. Poly(3-hexylthiophene)-b-poly (poly (ethylene glycol) methyl ether acrylate) (P3HT-b-PPEGA), a conjugated block copolymer compatible with polyaluminasilazane, is used to functionalize MWCNT surfaces with PPEGA, providing a noninvasive approach to disperse carbon nanotubes in polyaluminasilazane chloroform solutions. The electrospinning of the MWCNT/polyaluminasilazane solutions generates polymer fibers with aligned MWCNTs where MWCNTs are oriented along the electrospun jet by a sink flow. The subsequent pyrolysis of the obtained composite fibers produces ceramic fibers with aligned MWCNTs. The study of the effect of polymer and CNT concentration on the fiber structures shows that the fiber size increases with the increment of polymer concentration, whereas higher CNT content in the polymer solutions leads to thinner fibers attributable to the increased conductivity. Both the SEM and TEM characterization of the polymer and ceramic fibers demonstrates the uniform orientation of CNTs along the fibers, suggesting excellent dispersion of CNTs and efficient CNT alignment via the electrospinning. The electrical conductivity of a ceramic fibers with 1.2% aligned MWCNTs is measured to be 1.58 x 10(-6) S/cm, which is more than 500 times higher than that of bulk ceramic (3.43 x 10(-9) S/cm). Such an approach provides a versatile method to disperse CNTs in preceramic polymer solutions and offers a new approach to integrate aligned CNTs in ceramics.

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

    PubMed

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

    2012-10-01

    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.

  18. 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

  19. Electrical and optical properties of reduced graphene oxide and multi-walled carbon nanotubes based nanocomposites: A comparative study

    NASA Astrophysics Data System (ADS)

    Goumri, Meryem; Lucas, Bruno; Ratier, Bernard; Baitoul, Mimouna

    2016-10-01

    Graphene and multi-walled carbon nanotubes have attracted interest for a number of potential applications. One of the most actively pursued applications uses graphene and carbon nanotubes as a transparent conducting electrode in solar cells, displays or touch screens. In this work, in situ reduced graphene oxide/Poly (vinyl alcohol) and multi-walled carbon nanotubes/Sodium Dodecyl Sulfate/Poly (vinyl alcohol) composites were prepared by water dispersion and different reduction treatments. Comparative studies were conducted to explore the electrical and optical properties of nanocomposites based on graphene and multi-walled carbon nanotubes. A thermal reduction of graphene oxide was more effective, producing films with sheet resistances as low as 102-103 Ω/square with 80% transmittance for 550 nm light. The percolation threshold of the thermally reduced graphene oxide composites (0.35 vol%) was much lower than that of the chemically reduced graphene oxide composites (0.57 vol%), and than that of the carbon nanotubes composites (0.47 vol%). The Seebeck coefficient of graphene oxide films changes from about 40 μV/K to -30 μV/K after an annealing of three hours at 200 °C. The optical absorption of the nanocomposites showed a high absorbance in near UV regions and the photoluminescence enhancement was achieved at 1 wt% graphene loading, while the carbon nanotubes based composite presents a significant emission at 0.7 wt% followed with a photoluminescence quenching at higher fraction of the nanofillers 1.6 wt% TRGO and 1 wt% MWCNTs.

  20. Functionalization of multi-walled carbon nanotubes with a silane coupling agent and synthesis of polyimide nanocomposite.

    PubMed

    Zhang, Qingxin; Naito, Kimiyoshi; Kagawa, Yutaka

    2009-01-01

    Multi-walled carbon nanotubes (MWCNTs) were modified with an H2SO4/HNO, acid treatment, and subsequently functionalized with a (3-glycidyloxyporpl)trimethoxysilane coupling agent. The functionalized MWCNTs showed considerably improved dispersion in H2O and N-Methyl-2-pyrrolidinone (NMP), and the MWCNT suspension exhibited long-term stability. The functionalized MWCNTs were characterized with Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM) with an attached energy dispersive X-ray analyzer. Polyimide (PI)/MWCNT nanocomposites were synthesized from 4,4'-oxydianiline (ODA) and 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) using NMP as solvent. Improved MWCNT dispersion and enhanced interfacial adhesion were observed on the tensile fracture surfaces of the polyimide nanocomposite with functionalized MWCNTs.

  1. The Electrical Properties of Hybrid Composites Based on Multiwall Carbon Nanotubes with Graphite Nanoplatelets

    NASA Astrophysics Data System (ADS)

    Perets, Yulia; Aleksandrovych, Lyudmila; Melnychenko, Mykola; Lazarenko, Oleksandra; Vovchenko, Lyudmila; Matzui, Lyudmila

    2017-06-01

    In the present work, we have investigated the concentration dependences of electrical conductivity of monopolymer composites with graphite nanoplatelets or multiwall carbon nanotubes and hybrid composites with both multiwall carbon nanotubes and graphite nanoplatelets. The latter filler was added to given systems in content of 0.24 vol%. The content of multiwall carbon nanotubes is varied from 0.03 to 4 vol%. Before incorporation into the epoxy resin, the graphite nanoplatelets were subjected to ultraviolet ozone treatment for 20 min. It was found that the addition of nanocarbon to the low-viscosity suspension (polymer, acetone, hardener) results in formation of two percolation transitions. The percolation transition of the composites based on carbon nanotubes is the lowest (0.13 vol%).

  2. 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 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.

  3. Electrochemical sensor for chloramphenicol based on novel multiwalled carbon nanotubes@molecularly imprinted polymer.

    PubMed

    Yang, Guangming; Zhao, Faqiong

    2015-02-15

    Herein, we present a novel electrochemical sensor for the determination of chloramphenicol (CAP), which is based on multiwalled carbon nanotubes@molecularly imprinted polymer (MWCNTs@MIP), mesoporous carbon (CKM-3) and three-dimensional porous graphene (P-r-GO). Firstly, 3-hexadecyl-1-vinylimidazolium chloride (C16VimCl) was synthetized by using 1-vinylimidazole and 1-chlorohexadecane as precursors. Then, C16VImCl was used to improve the dispersion of MWCNT and as monomer to prepare MIP on MWCNT surface to obtain MWCNTs@MIP. After that, the obtained MWCNTs@MIP was coated on the CKM-3 and P-r-GO modified glassy carbon electrode to construct an electrochemical sensor for the determination of CAP. The parameters concerning this assay strategy were carefully considered. Under the optimal conditions, the electrochemical sensor offered an excellent response for CAP. The linear response ranges were 5.0 × 10(-9)-5 × 10(-7)mol L(-1) and 5.0 × 10(-7)-4.0 × 10(-6), respectively, and the detection limit was 1.0 × 10(-10)mol L(-1). The electrochemical sensor was applied to determine CAP in real samples with satisfactory results. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. 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...

  5. 40 CFR 721.10277 - Single-walled and multi-walled carbon nanotubes (generic) (P-10-40).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... chemical substance identified generically as single-walled and multi-walled carbon nanotubes (PMN P-10-40... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Single-walled and multi-walled carbon nanotubes (generic) (P-10-40). 721.10277 Section 721.10277 Protection of Environment ENVIRONMENTAL...

  6. 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.

  7. Synergistic effect of ionic liquid intercalation and multiwalled carbon nanotube spacers with improved supercapacitor performance

    NASA Astrophysics Data System (ADS)

    Liu, Xiangyang; Guo, Jianhui; Chen, Jianping; Zhang, Jiwei; Zhang, Jingwei

    2017-09-01

    The restacking of reduced graphene oxide (RGO) with undesirable energy density and power density is still a thorny issue. In our work, we proposed a simple strategy from incorporating ionic liquid (IL) and multiwalled carbon nanotubes (MWCNTs) in turn to impede the RGO sheets aggragation. With synergistic effect of IL ions intercalation and MWCNTs spacers, a uniformly dispersed hierarchical pore structure was obtained. For RGO-IL-MWCNTs, a very high specific surface area (588.7 m2 g-1) with enhanced fraction of mesopores and macropores can provide more accessible areas and pathways for charge accommodation and IL diffusion. This optimized hierarchical pore structure possesses a high specific capacity of 269.3 F g-1 (at 2 mV s-1) and a very high energy density of 131.8 Wh kg-1 (at a power density of 892.6 W kg-1) in pure IL electrolyte at room temperature. Interestingly, this simple method probably offers excellent potential for large-scale production of dispersed two-dimensional layered materials with superior performance.

  8. 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.

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

    SciTech Connect

    Ahmad, Iftikhar; Islam, Mohammad; Dar, Mushtaq Ahmad; Xu, Fang; Shah, Syed Ismat; Zhu, Yanqiu

    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 (~ 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}.

  10. 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

  11. 3D printing nano conductive multi-walled carbon nanotube scaffolds for nerve regeneration.

    PubMed

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

    2018-02-01

    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. 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. 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. 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.

  12. 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

  13. 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.

  14. Electrospinning fabrication of high strength and toughness polyimide nanofiber membranes containing multiwalled carbon nanotubes.

    PubMed

    Chen, Dan; Liu, Tianxi; Zhou, Xiaoping; Tjiu, Wuiwui Chauhari; Hou, Haoqing

    2009-07-23

    Polyimide (PI) and PI nanocomposite fibers containing different amounts of multiwalled carbon nanotubes (MWNTs) were produced for the first time by electrospinning. The membranes prepared were composed of highly aligned nanofibers and showed significant enhancement in mechanical properties, compared with the membranes prepared by conventional solution-casting method. Surface-functionalized MWNTs were homogeneously dispersed and highly aligned along the fiber axis, whereas most of the pristine MWNTs formed aggregates or bundles and even protruded out of the electrospun nanofibers. The thermal and mechanical properties of polyimide matrix were significantly improved with the incorporation of MWNTs. And the elongation at break of the nanofiber membranes can reach 100% for the nanotube loading level of 3.5 wt %. It was found that electrospinning the in situ prepared MWNT/poly(amic acid) solution can achieve better polymer chain orientation and thus better mechanical properties of the as-prepared membranes. Our study demonstrates a good example for the preparation of high-performance polymer/carbon nanotube nanocomposites by using electrospinning.

  15. Amidation of multiwalled carbon nanotubes in mild and efficient conditions.

    PubMed

    Moradi, Leila; Mohajeri, Ali; Naeimi, Hossein; Rashidi, Ali Morad

    2013-03-01

    Functionalization of Multi Walled Carbon Nanotubes (MWCNTs) with amines under a two step reaction is studied. In the first step, maleic anhydride graft to the MWCNT (Mah-g-MWCNTs) surfaces via a polymerization process with benzoylproxide as initiator. Active anhydride groups on the surfaces of MWCNTs, react with amines to give a polyamido chain attached to the MWCNTs surfaces. The reaction products have high solubility and disperse stability in organic solvents. FTIR, TGA and elemental analysis (CHN) were used to characterization of the achieved products.

  16. Electrochemical study of lincomycin on a multi-wall carbon nanotubes modified glassy carbon electrode and its determination in tablets.

    PubMed

    Wu, Yunhua; Ye, Shaohua; Hu, Shengshui

    2006-06-07

    Multi-wall carbon nanotubes (MWNTs) were dispersed in dihexadecylphosphate (DHP), sodium dodecylbenzenesulfonate (SDBS), and Nafion to give a homogeneous and stable suspension, respectively. MWNTs film in different solvents was fabricated onto a glassy carbon electrode (GCE) with an easy and convenient method. It was found that on MWNTs-DHP film lincomycin exhibited a well-defined oxidation peak. The electrochemical behavior of lincomycin at coated GCE was investigated by cyclic voltammetry and chronocoulometry. The MWNTs-DHP film modified glassy carbon electrode shows obvious electrocatalytic activity to the oxidation of lincomycin, since it greatly enhances the oxidation peak current of lincomycin as well as lowers its oxidation overpotential. Based on this, a very sensitive and simple voltammetric method was developed for the measurement of lincomycin. A sensitive linear voltammetric response for lincomycin was obtained in the concentration range of 4.5x10(-7) to 1.5x10(-4) mol/l, and the detection limit is 2.0x10(-7) mol/l using linear sweep voltammetry. Compared with other methods, this proposed method possesses many advantages such as very low detection limit, fast response, low cost and simplicity. The practical application was demonstrated to determine lincomycin in tablets with good result.

  17. 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...

  18. 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.

  19. Synthesis and characterization of CdS nanoparticle based multiwall carbon nanotube-maleic anhydride-1-octene nanocomposites

    NASA Astrophysics Data System (ADS)

    Malikov, E. Y.; Altay, M. C.; Muradov, M. B.; Akperov, O. H.; Eyvazova, G. M.; Puskás, R.; Madarász, D.; Kukovecz, Á.; Kónya, Z.

    2015-05-01

    CdS nanoparticles were synthesized by sonication from cadmium chloride and thiourea using a multiwall carbon nanotube (MWCNT)-maleic anhydride (MA)-1-octene system as the matrix. The matrix was obtained by the "grafting from" approach from oxidized carbon nanotubes and maleic anhydride-1-octene. Multiwall carbon nanotubes used for reinforcing the matrix were synthesized by Catalytic Chemical Vapor Deposition using Fe-Co/Al2O3 as the catalyst. The obtained nanostructures were characterized by FTIR, XRD, Raman spectroscopy, TEM, SEM and UV-vis spectroscopy. The average CdS particle diameter was 7.9 nm as confirmed independently by TEM and XRD. UV-vis spectroscopy revealed that the obtained nanostructure is an appropriate base material for making optical devices. The novelty of this work is the use of the MWCNT-MA-1-octene matrix obtained via the "grafting from" approach for the synthesis of uniformly dispersed CdS nanocrystals by ultrasonic cavitation to obtain a polymer nanocomposite.

  20. Infrared photoluminescence of composite films containing quasi-isolated multiwalled carbon nanotubes and carbon nanoshells.

    PubMed

    Reyes-Reyes, M; Segura-Cardenas, E; Gorbatchev, A Yu; López-Sandoval, R

    2010-07-01

    Films of small irregular-shaped aggregates composed by several layers of turbostratic graphite encapsulating iron nanoparticles, like carbon nanoshells, and quasi-isolated multi-walled carbon nanotubes (MWCNTs), were synthesized by the chemical vapor deposition method on glass substrates. Quasi-isolated MWCNTs were found emerging in different directions on the agglomerates composed of carbon nanoshells. The morphological properties of the films were characterized using scanning electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy, whereas their optical properties were investigated using optical absorption and photoluminescence (PL) spectroscopy. The studies show a high-intensity PL signal in the infrared at room temperature. This PL signal shows several peaks, which cannot be explained by a blackbody emission. However, the overall PL signal could be a combination of the black emission and electronic transitions. Furthermore, the observed infrared PL emission could be ideal for potential applications such as in gas sensors, infrared detectors and so on.

  1. A comparative study of EMI shielding properties of carbon nanofiber and multi-walled carbon nanotube filled polymer composites.

    PubMed

    Yang, Yonglai; Gupta, Mool C; Dudley, Kenneth L; Lawrence, Roland W

    2005-06-01

    Electromagnetic interference shielding properties of carbon nanofiber- and multi-walled carbon nanotube-filled polystyrene composites were investigated in the frequency range of 8.2-12.4 GHz (X-band). It was observed that the shielding effectiveness of composites was frequency independent, and increased with the increase of carbon nanofiber or nanotube loading. At the same filler loading, multi-walled carbon nanotube-filled polystyrene composites exhibited higher shielding effectiveness compared to those filled with carbon nanofibers. In particular, carbon nanotubes were more effective than nanofibers in providing high EMI shielding at low filler loadings. The experimental data showed that the shielding effectiveness of the composite containing 7 wt% carbon nanotubes could reach more than 26 dB, implying that such a composite can be used as a potential electromagnetic interference shielding material. The dominant shielding mechanism of carbon nanotube-filled polystyrene composites was also discussed.

  2. Planar gas chromatography column on aluminum plate with multi-walled carbon nanotubes as stationary phase

    NASA Astrophysics Data System (ADS)

    Platonov, I. A.; Platonov, V. I.; Pavelyev, V. S.

    2016-04-01

    The high selectivity of the adsorption layer for low-boiling alkanes is shown, the separation factor (α) couple iso-butane / butane is 1.9 at a column temperature of 50 °C.The paper presents sorption and selective properties of planar gas chromatography column on aluminum plate with multi-walled carbon nanotubes as the stationary phase.

  3. Activity of site-specific endonucleases on complexes of plasmid DNA with multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Egorova, V. P.; Krylova, H. V.; Lipnevich, I. V.; Veligura, A. A.; Shulitsky, B. G.; Asayonok, A. A.; Vaskovtsev, E. V.

    2016-08-01

    We have synthesized and investigated structural and functional properties of plasmid DNA complexes with multi-walled carbon nanotubes (MWCNTs) for detection of changes in structural state of the plasmid DNA at its recognition by site-specific endonuclease. It has been also established that the site-specific endonuclease is functionally active on the surface of MWCNTs.

  4. 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...

  5. Functionalization of Multi-Walled Carbon Nanotubes with Cysteamine for the Construction of Cnt/gold Nanoparticle Hybrid Nanostructures

    NASA Astrophysics Data System (ADS)

    Kumar, Nanjundan Ashok; Kim, Sung Hun; Kim, Jong Su; Kim, Jong Tae; Jeong, Yeon Tae

    Combining hybrid nanostructures of metal nanoparticles (NPs) and carbon nanotubes could afford a novel strategy to prepare promising nanomaterials for the highly sensitive sensors and imaging science applications. Conventional acid oxidation process was used to obtain carboxylic acid bound multi-walled carbon nanotubes (MWNTs) which was further acylated with thionyl chloride to give acyl chloride functionalized MWNTs. Thiol functionalized MWNTs were synthesized by amidation reaction of the acylated MWNTs with cysteamine. Further, gold nanoparticles (GNPs) were successfully fabricated on the tube walls to yield the CNT/Au hybrid. Fourier transform infrared spectroscopy and energy dispersive X-ray studies were used to characterize the surface chemical functionalities and composition of MWNTs, respectively. Evidence for the attachment of GNPs to thiol functionalized MWNTs was obtained from ultraviolet-visible absorption spectra. In addition, TEM images provided a vivid image of uniform decoration of GNPs on the nanotube sidewalls.

  6. 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...

  7. Peptide Probe for Multi-walled Carbon Nanotubes: Electrophoretic Assessment of the Binding Interface and Evaluation of Surface Functionalization.

    PubMed

    Davis, Tyler A; Holland, Lisa Ann

    2018-02-22

    Non-covalent interactions of peptides and proteins with carbon nanotubes play a key role in sensing, dispersion and biocompatibility. Advances in these areas require that the forces which contribute to physical adsorption are understood in order that the carbon nanotubes present a degree of functionalization appropriate to the desired application. Affinity analyses of peptides are employed to evaluate the role of tryptophan and arginine residues on physical adsorption to carboxylated multi-walled carbon nanotubes. Peptides containing arginine and tryptophan, WR(W)n, are used with affinity capillary electrophoresis to identify factors that lead to the formation of peptide-carbon nanotube complex. The effects of changing the amino acid composition and residue length are evaluated by measuring dissociation constants. Electrostatic interactions contribute significantly to complexation with the strongest interaction observed using the peptide WRWWWW and carboxylated carbon nanotube. Stronger interaction is observed when the tryptophan content is successively increased as follows WR(W)4 > WR(W)3 > WR(W)2 > WRW > WR. However, as observed with polytryptophan (W5, W4, W3, W2), removing the arginine residue significantly reduces the interaction with carbon nanotubes. Increasing the arginine content to WRWWRW does improve binding, while replacing the arginine residue in WRWWWW with lysine (WKWWWW) reveals that lysine also contributes to surface adsorption, but not as effectively as arginine. These observations are used to guide a search of the primary sequence of lysozyme to identify short regions in the peptide that contain a single cationic residue and two aromatic residues. One candidate peptide sequence (WMCLAKW) from this search is analyzed by capillary electrophoresis. The dissociation constant of carboxylated multi-walled carbon nanotubes is measured for the peptide, WMCLAKW, to demonstrate the utility of the affinity capillary electrophoresis analysis.

  8. Multiwalled Carbon Nanotube Functionalization with High Molecular Weight Hyaluronan Significantly Reduces Pulmonary Injury.

    PubMed

    Hussain, Salik; Ji, Zhaoxia; Taylor, Alexia J; DeGraff, Laura M; George, Margaret; Tucker, Charles J; Chang, Chong Hyun; Li, Ruibin; Bonner, James C; Garantziotis, Stavros

    2016-08-23

    Commercialization of multiwalled carbon nanotubes (MWCNT)-based applications has been hampered by concerns regarding their lung toxicity potential. Hyaluronic acid (HA) is a ubiquitously found polysaccharide, which is anti-inflammatory in its native high molecular weight form. HA-functionalized smart MWCNTs have shown promise as tumor-targeting drug delivery agents and can enhance bone repair and regeneration. However, it is unclear whether HA functionalization could reduce the pulmonary toxicity potential of MWCNTs. Using in vivo and in vitro approaches, we investigated the effectiveness of MWCNT functionalization with HA in increasing nanotube biocompatibility and reducing lung inflammatory and fibrotic effects. We utilized three-dimensional cultures of differentiated primary human bronchial epithelia to translate findings from rodent assays to humans. We found that HA functionalization increased stability and dispersion of MWCNTs and reduced postexposure lung inflammation, fibrosis, and mucus cell metaplasia compared with nonfunctionalized MWCNTs. Cocultures of fully differentiated bronchial epithelial cells (cultivated at air-liquid interface) and human lung fibroblasts (submerged) displayed significant reduction in injury, oxidative stress, as well as pro-inflammatory gene and protein expression after exposure to HA-functionalized MWCNTs compared with MWCNTs alone. In contrast, neither type of nanotubes stimulated cytokine production in primary human alveolar macrophages. In aggregate, our results demonstrate the effectiveness of HA functionalization as a safer design approach to eliminate MWCNT-induced lung injury and suggest that HA functionalization works by reducing MWCNT-induced epithelial injury.

  9. 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.

  10. Development of functionalized multi-walled carbon-nanotube-based alginate hydrogels for enabling biomimetic technologies

    NASA Astrophysics Data System (ADS)

    Joddar, Binata; Garcia, Eduardo; Casas, Atzimba; Stewart, Calvin M.

    2016-08-01

    Alginate is a hydrogel commonly used for cell culture by ionically crosslinking in the presence of divalent Ca2+ ions. However these alginate gels are mechanically unstable, not permitting their use as scaffolds to engineer robust biological bone, breast, cardiac or tumor tissues. This issue can be addressed via encapsulation of multi-walled carbon nanotubes (MWCNT) serving as a reinforcing phase while being dispersed in a continuous phase of alginate. We hypothesized that adding functionalized MWCNT to alginate, would yield composite gels with distinctively different mechanical, physical and biological characteristics in comparison to alginate alone. Resultant MWCNT-alginate gels were porous, and showed significantly less degradation after 14 days compared to alginate alone. In vitro cell-studies showed enhanced HeLa cell adhesion and proliferation on the MWCNT-alginate compared to alginate. The extent of cell proliferation was greater when cultured atop 1 and 3 mg/ml MWCNT-alginate; although all MWCNT-alginates lead to enhanced cell cluster formation compared to alginate alone. Among all the MWCNT-alginates, the 1 mg/ml gels showed significantly greater stiffness compared to all other cases. These results provide an important basis for the development of the MWCNT-alginates as novel substrates for cell culture applications, cell therapy and tissue engineering.

  11. Characterization of multiwalled carbon nanotube-reinforced hydroxyapatite composites consolidated by spark plasma sintering.

    PubMed

    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.

  12. Adsorption of tetracycline from aqueous solutions onto multi-walled carbon nanotubes with different oxygen contents

    PubMed Central

    Yu, Fei; Ma, Jie; Han, Sheng

    2014-01-01

    Oxidized multi-walled carbon nanotubes (MWCNTs) with different oxygen contents were investigated for the adsorption of tetracycline (TC) from aqueous solutions. As the surface oxygen content of the MWCNTs increased, the maximum adsorption capacity and adsorption coefficient of TC increased to the largest values and then decreased. The relation can be attributed to the interplay between the nanotubes' dispersibility and the water cluster formation upon TC adsorption. The overall adsorption kinetics of TC onto CNTs-3.2%O might be dependent on both intra-particle diffusion and boundary layer diffusion. The maximum adsorption capacity of TC on CNTs-3.2%O was achieved in the pH range of 3.3–8.0 due to formation of water clusters or H-bonds. Furthermore, the presence of Cu2+ could significantly enhanced TC adsorption at pH of 5.0. However, the solution ionic strength did not exhibit remarkable effect on TC adsorption. In addition, when pH is beyond the range (3.3–8.0), the electrostatic interactions caused the decrease of TC adsorption capacity. Our results indicate that surface properties and aqueous solution chemistry play important roles in TC adsorption on MWCNTs. PMID:24937315

  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. Growth mechanism of long aligned multiwall carbon nanotube arrays by water-assisted chemical vapor deposition.

    PubMed

    Yun, YeoHeung; Shanov, Vesselin; Tu, Yi; Subramaniam, Srinivas; Schulz, Mark J

    2006-11-30

    Highly aligned arrays of multiwalled carbon nanotube (MWCNT) on layered Si substrates have been synthesized by chemical vapor deposition (CVD). The effect of the substrate design and the process parameters on the growth mechanism were studied. Adding water vapor to the reaction gas mixture of hydrogen and ethylene enhanced the growth which led to synthesis of longer CNT arrays with high density. Environmental scanning electron microscopy (ESEM), energy-dispersive spectroscopy (EDS), and atomic force microscopy (AFM) were used to analyze the CNT morphology and composition. Quadrupole mass spectroscopy (QMS) provided in-situ information on the gas spices within the reaction zone. On the basis of results, we verified the top growth mechanism and evaluated the reason of decline and stoppage of the CNT growth after extended period of deposition. Multilayered Si substrates with a top film of Al2O3, having appropriate roughness, provide favorable conditions to form catalyst islands with uniform distribution and size. Using water-assisted CVD process and optimized substrate design, our group succeeded to grow vertically aligned, patterned MWCNT up to 4-mm long. The arrays were of high purity and weak adhesion which allowed to be peeled off easily from the substrate.

  15. 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.

  16. Numerical characterization of magnetically aligned multiwalled carbon nanotube-Fe3O4 nanoparticle complex.

    PubMed

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

    2015-02-11

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

  17. Multi-walled carbon nanotubes fabricated by electrospinning of acrylonitrile/nylon solution and subsequent carbonization.

    PubMed

    Park, Soo-Jin; Parajuli, Daman Chandra; Bajagi, Madhab Prasad; Jeong, Kwang-Un; Barakat, Nasser Aly Mohamed; Kim, Hak Yong

    2010-08-01

    The poly(acrylonitrile) (PAN) nanofiber web interpenetrated nylon-6 nanofiber supporters were prepared by electrospinning of an acrylonitrile (AN)/nylon-6 solution. It was realized that the average diameters of PAN and nylon-6 nanofiber were 20 and 100 nm, respectively, and that the PAN nanofibers constructed spider-mat networks which were supported by the robust nylon-6 nanofiber pillars. After stabilization and carbonization above 600 degrees C, both hollow-shaped and bamboo-shaped multi-walled carbon nanotubes (MWCNTs) were formed with the diameter range from 5 to 20 nm. The morphology and structure of MWCNTs had been further investigated by the combination techniques of transmission electron microscopy (TEM), electron diffraction (ED), X-ray diffraction (XRD) and elemental analyzer (EA).

  18. 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.

  19. 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; Kim, Junhyo; Noh, Jungpil; Huh, Sunchul; Chung, Hanshik; Jeong, Hyomin

    2016-01-15

    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 and 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.

  20. 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

    2016-01-15

    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

  1. Ruthenium(0) nanoparticles supported on multiwalled carbon nanotube as highly active catalyst for hydrogen generation from ammonia-borane.

    PubMed

    Akbayrak, Serdar; Ozkar, Saim

    2012-11-01

    Ruthenium(0) nanoparticles supported on multiwalled carbon nanotubes (Ru(0)@MWCNT) were in situ formed during the hydrolysis of ammonia-borane (AB) and could be isolated from the reaction solution by filtration and characterized by ICP-OES, XRD, TEM, SEM, EDX, and XPS techniques. The results reveal that ruthenium(0) nanoparticles of size in the range 1.4-3.0 nm are well-dispersed on multiwalled carbon nanotubes. They were found to be highly active catalyst in hydrogen generation from the hydrolysis of AB with a turnover frequency value of 329 min⁻¹. The reusability experiments show that Ru(0)@MWCNTs are isolable and redispersible in aqueous solution; when redispersed they are still active catalyst in the hydrolysis of AB exhibiting a release of 3.0 equivalents of H₂ per mole of NH₃BH₃ and preserving 41% of the initial catalytic activity even after the fourth run of hydrolysis. The lifetime of Ru(0)@MWCNTs was measured as 26400 turnovers over 29 h in the hydrolysis of AB at 25.0 ± 0.1 °C before deactivation. The work reported here also includes the kinetic studies depending on the temperature to determine the activation energy of the reaction (E(a) = 33 ± 2 kJ/mol) and the effect of catalyst concentration on the rate of the catalytic hydrolysis of AB, respectively.

  2. 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.

  3. 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.

  4. Characterization of fluorinated multiwalled carbon nanotubes by x-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Brzhezinskaya, M. M.; Vinogradov, N. A.; Muradyan, V. E.; Shul'Ga, Yu. M.; Polyakova, N. V.; Vinogradov, A. S.

    2008-03-01

    The C 1 s and F 1 s x-ray absorption spectra of fluorinated multiwalled carbon nanotubes with different fluorine contents and reference compounds (highly oriented pyrolytic graphite crystals and "white" graphite fluoride) were measured using the equipment of the Russian-German beamline at the BESSY II storage ring with a high energy resolution. The spectra obtained were analyzed with the aim of characterizing multiwalled carbon nanotubes and their products formed upon treatment of the nanotubes with fluorine at a temperature of 420°C. It was established that, within the probing depth (˜15 nm) of carbon nanotubes, the process of fluorination occurs uniformly and does not depend on the fluorine concentration. The interaction of fluorine atoms with multiwalled carbon nanotubes in this case proceeds through the covalent attachment of fluorine atoms to graphene layers of the graphite skeleton and is accompanied by a change in the hybridization of the 2 s and 2 p valence electron states of the carbon atom from the trigonal ( sp 2) to tetrahedral ( sp 3) hybridization.

  5. Enhanced rate performance of multiwalled carbon nanotube encrusted olivine type composite cathode material using polyol technique

    NASA Astrophysics Data System (ADS)

    Muruganantham, R.; Sivakumar, M.; Subadevi, R.

    2015-12-01

    Olivine type multi-walled carbon nanotube encrusted LiFePO4/C composites have been prepared using economic and energy efficient simple polyol technique without any subsequent heat treatment. The prepared material has an olivine type orthorhombic phase. Also, the iron oxidation state is 2+, which is identified by X-ray diffraction and X-ray photoelectron spectroscopy. It is possible to attain the discharge capacity almost close to theoretical capacity of LiFePO4 as in high temperature methods with ∼100% coulombic efficiency. The specific surface area has been increased upon encrusting multi walled carbon nano tube on LiFePO4/C, which results in enhanced reversible capacity upto 166 mAh g-1 at C/10. Also, it exhibits 89 mAh g-1 even at 30 C rate. This is due to the formation of conductive networks by carbon nanotube, and excellent attachment of LiFePO4/C composite particles on multi-walled carbon nanotube, which induced the kinetics during intercalation/deintercalation process. Multi-walled carbon nanotube acts as the electro-conductive filler on the LiFePO4 surface. The direct addition of MWCNT would result better performances than blending the MWCNT with LiFePO4/C.

  6. Multiwalled Carbon Nanotube Forest Grown via Chemical Vapor Deposition from Iron Catalyst Nanoparticles, by XPS

    SciTech Connect

    Jensen, David S.; Kanyal, Supriya S.; Madaan, Nitesh; Vail, Michael A.; Dadson, Andrew; Engelhard, Mark H.; Linford, Matthew R.

    2013-09-25

    Carbon nanotubes (CNTs) have unique chemical and physical properties. Herein, we report an XPS analysis of a forest of multiwalled CNTs using monochromatic Al Kα radiation. Survey scans show only one element: carbon. The carbon 1s peak is centered 284.5 eV. The C 1s envelope also shows the expected π → π* shake-up peak at ca. 291 eV. The valence band and carbon KVV Auger signals are presented. When patterned, the CNT forests can be used as a template for subsequent deposition of metal oxides to make thin layer chromatography plates.1-3

  7. Fabrication of one-dimensional Ag/multiwalled carbon nanotube nano-composite

    PubMed Central

    2012-01-01

    Composite made of multiwalled carbon nanotubes coated with silver was fabricated by an electroless deposition process. The thickness of silver layer is about 40 to 60 nm, characterized as nano-crystalline with (111) crystal orientation along the nanotube's axial direction. The characterization of silver/carbon nanotube [Ag/CNT] nanowire has shown the large current carrying capability, and the electric conductivity is similar to the pure silver nanowires that Ag/CNT would be promising as building blocks for integrated circuits. PACS: 81.05.uj, carbon nanotubes, carbon-based materials, diamond/nanocarbon composites. PMID:22444640

  8. Fabrication of one-dimensional Ag/multiwalled carbon nanotube nano-composite

    NASA Astrophysics Data System (ADS)

    Peng, Yitian; Chen, Quanfang

    2012-03-01

    Composite made of multiwalled carbon nanotubes coated with silver was fabricated by an electroless deposition process. The thickness of silver layer is about 40 to 60 nm, characterized as nano-crystalline with (111) crystal orientation along the nanotube's axial direction. The characterization of silver/carbon nanotube [Ag/CNT] nanowire has shown the large current carrying capability, and the electric conductivity is similar to the pure silver nanowires that Ag/CNT would be promising as building blocks for integrated circuits. PACS: 81.05.uj, carbon nanotubes, carbon-based materials, diamond/nanocarbon composites.

  9. Fabrication of one-dimensional Ag/multiwalled carbon nanotube nano-composite.

    PubMed

    Peng, Yitian; Chen, Quanfang

    2012-03-23

    Composite made of multiwalled carbon nanotubes coated with silver was fabricated by an electroless deposition process. The thickness of silver layer is about 40 to 60 nm, characterized as nano-crystalline with (111) crystal orientation along the nanotube's axial direction. The characterization of silver/carbon nanotube [Ag/CNT] nanowire has shown the large current carrying capability, and the electric conductivity is similar to the pure silver nanowires that Ag/CNT would be promising as building blocks for integrated circuits.PACS: 81.05.uj, carbon nanotubes, carbon-based materials, diamond/nanocarbon composites.

  10. 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.

  11. Structure and Crystallization Behavior of Nylong 66/Multi-Walled Carbon Nanotube Nanocomposites at Low Carbon Nanotube Contents

    SciTech Connect

    Li,L.; Li, C.; Ni, C.

    2007-01-01

    Multi-walled carbon nanotubes (MWNTs) were modified with poly(hexamethylene adipamide) (also known as Nylon 66) via a controlled polymer solution crystallization method. A 'nanohybrid shish kebab' (NHSK) structure was found wherein the MWNT resembled the shish while Nylon 66 lamellar crystals formed the kebabs. These Nylon 66-functionalized MWNTs were used as precursors to prepare polymer/MWNT nanocomposites. Excellent dispersion was revealed by optical and electron microscopies. Nitric acid etching of the nanocomposites showed that MWNT formed a robust network in Nylon 66. Non-isothermal DSC results showed multiple melting peaks, which can be attributed to lamellar thickness changes upon heating. The crystallite sizesmore » L{sub 100} and L{sup 010} of Nylon 66, determined by WAXD, decreased with increasing MWNT contents. Isothermal DSC results showed that crystallization kinetics increased first and then decreased with increasing MWNT contents in Nylon 66. This study showed that the effect of MWNTs on Nylon 66 crystallization is twofold: MWNTs provide heterogeneous nucleation sites for Nylon 66 crystallization while the tube network structure hinders large crystal growth.« less

  12. 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

  13. 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

  14. Immobilization of platinum nanoparticles on 3,4-diaminobenzoyl-functionalized multi-walled carbon nanotube and its electrocatalytic activity

    NASA Astrophysics Data System (ADS)

    Choi, Hyun-Jung; Kang, Ji-Ye; Jeon, In-Yup; Eo, Soo-Mi; Tan, Loon-Seng; Baek, Jong-Beom

    2012-02-01

    Multi-walled carbon nanotubes (MWCNTs) are functionalized at the sp2 C-H defect sites with 3,4-diaminobenzoic acid by a "direct" Friedel-Crafts acylation reaction in a mild polyphosphoric acid/phosphorous pentoxide medium. Owing to enhanced surface polarity, the resulting 3,4-diaminobenzoyl-functionalized MWCNTs (DAB-MWCNT) are highly dispersible in polar solvents, such as ethanol, N-methyl-2-pyrrolidone, and methanesulfonic acid. The absorption and emission properties of DAB-MWCNT in solution state are qualitatively shown to be sensitive to the pH in the environment. The DAB-MWCNT is used as a stable platform on which to deposit platinum nanoparticles (PNP). The PNP/DAB-MWCNT hybrid displays high electrocatalytic activity with good electrochemical stability for an oxygen reduction reaction under an alkaline condition.

  15. 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.

  16. 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.

  17. Short-term splenic impact of single-strand DNA functionalized multi-walled carbon nanotubes intraperitoneally injected in rats.

    PubMed

    Clichici, Simona; Biris, Alexandru Radu; Catoi, Cornel; Filip, Adriana; Tabaran, Flaviu

    2014-04-01

    In recent years, a great deal of studies have focused on the possible toxicity of carbon nanotubes (CNT), as a result of their potential applications in the field of nanotechnologies. The investigation of spleen toxicity is part of the carbon nanotubes-induced toxicity assessment. In this study, we investigated the possible toxic effects of CNT on the rat spleen, after intraperitoneally (i.p.) administration of a single dose [1.5 ml; 2 mg multi-walled (MW) CNT per body weight (bw)] of multi-walled carbon nanotubes (exterior diameter 15-25 nm, interior diameter 10-15 nm, surface 88 m(2) g(-1) ) functionalized 1:1 with single-strand DNA (ss-DNA-MWCNT, 270 mg l(-1) ). CNT functionalization with DNA determines a stable dispersion in the body fluids. For the detection of carbon nanotubes in the spleen, Raman spectroscopy, histopathologic examination, confocal microscopy and transmission electron microscopy (TEM) were performed at different time points (1, 6, 24, 48 and 144 h) after MWCNT administration. The dynamics of oxidative stress parameters (malondialdehyde, protein carbonyls and reduced glutathione), along with nitrosative stress parameters (nitric oxide, inducible NO synthase), the pro-inflammatory cytokines [interleukin-(IL)-1β] and the number of cells expressing caspase 3 and proliferating cell nuclear antigen (PCNA) were assessed. Our results indicate that, after i.p. administration, MWCNT translocate progressively in the spleen, with a peak of concentration after 48 h, and determine lymphoid hyperplasia and an increase in the number of cells which undergo apoptosis, in parallel with the enhancement of the mitosis in the white pulp and with transient alterations of oxidative stress and inflammation that need further investigations for a longer period of monitoring. Copyright © 2013 John Wiley & Sons, Ltd.

  18. Mechanisms for how inhaled multiwalled carbon nanotubes suppress systemic immune function in mice

    NASA Astrophysics Data System (ADS)

    Mitchell, L. A.; Lauer, F. T.; Burchiel, S. W.; McDonald, J. D.

    2009-07-01

    The potential health effects of inhaling carbon nanotubes are important because of possible exposures in occupational settings. Previously, we have shown mice that have inhaled multiwalled carbon nanotubes have suppressed systemic immune function. Here, we show the mechanisms for this immune suppression. Mice were exposed to 0, 0.3 or 1 mg m-3 multiwalled carbon nanotubes for 6 h per day for 14 consecutive days in whole-body inhalation chambers. Only those exposed to a dose of 1 mg m-3 presented suppressed immune function; this involved activation of cyclooxygenase enzymes in the spleen in response to a signal from the lungs. Spleen cells from exposed animals partially recovered their immune function when treated with ibuprofen, a drug that blocks the formation of cyclooxygenase enzymes. Knockout mice without cyclooxygenase enzymes were not affected when exposed to multiwalled carbon nanotubes, further confirming the importance of this enzyme in suppression. Proteins from the lungs of exposed mice suppressed the immune function of spleen cells from normal mice, but not those from knockout mice. Our findings suggest that signals from the lung can activate signals in the spleen to suppress the immune function of exposed mice.

  19. Low temperature growth of carbon nanotubes with aligned multiwalls by microwave plasma-CVD

    NASA Astrophysics Data System (ADS)

    Roy, Ajay; Das, Debajyoti

    2017-05-01

    Multiwall carbon nanotubes (MW-CNTs) have been prepared in a microwave-plasma enhanced CVD (MW-PECVD) tubular system at a low temperature ˜300 °C from CH4-H2 plasma with the addition of CO2 using as a week oxidant to selectively remove the amorphous carbon component and promote the CNT growth. CNTs are typically with outer diameter ˜20 nm, inner diameter ˜10 nm of several μm in length and are grown via the tip growth process, bearing Fe catalyst nano-particles at the tip. The presence of CO2 as a weak oxidant in the plasma may influence in reducing the size of the support catalyst nano-particles and narrowing the CNTs with aligned multiwalls.

  20. Field Emission from Multi-Walled Carbon Nanotubes — Its applications in NEMS

    NASA Astrophysics Data System (ADS)

    Sveningsson, M.; Lee, S. W.; Park, Y. W.; Campbell, E. E. B.

    2005-09-01

    Nanoelectromechanical systems (NEMS) are a rapidly growing area of research. We discuss here the fabrication of two different three terminal nanorelay structures based on multi-walled carbon nanotubes (MWNT). Using a gate voltage the whole MWNT can be deflected and the tip of the carbon nanotube can be moved closer to a drain electrode making physical contact. In another device structure the carbon nanotubes are shorter so they never can get real physical contact with the drain electrode, instead this device is based on the process of electron field emission from the MWNT.

  1. Interaction of multi-walled carbon nanotubes with water-soluble proteins: effect of sidewall carboxylation.

    PubMed

    Takada, Tomoya; Kurosaki, Rei; Konno, Yuji; Abe, Shigeaki

    2014-04-01

    Effect of sidewall carboxylation on protein adsorption behavior of multi-walled carbon nanotubes (MWCNTs) was studied. Two water-soluble proteins, bovine serum albumin (BSA) and egg white lysozyme (LYS), were employed in this work. Carboxylation of MWCNTs suppressed adsorption of BSA, whereas adsorption of LYS was enhanced by the carboxylation. These behaviors are explained by the difference in the dominance of hydrophobic interaction and ionic interaction between MWCNTs and the proteins.

  2. Structural ordering of multi-walled carbon nanotubes (MWCNTs) caused by gamma (γ)-ray irradiation

    SciTech Connect

    Silambarasan, D., E-mail: simbuphysics@yahoo.com; Vasu, V.; Iyakutti, K.

    2015-06-24

    Multi-walled carbon nanotubes (MWCNTs) were irradiated by Gamma (γ)-rays in air with absorbed doses of 25 and 50 kGy. As a result of γ-ray irradiation, the inter-wall distance of MWCNTs was decreased and their graphitic order was improved. The reduction in inter-wall distance and structural ordering was improved with the increasing dosage of irradiation. Experimental evidences are provided by powder XRD and micro-Raman analyses.

  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. Ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotube mixtures

    NASA Astrophysics Data System (ADS)

    Kozulin, Alexander A.; Vorozhtsov, Sergey A.; Kulkov, Sergey S.; Teipel, U.; Kulkov, Sergey N.

    2015-10-01

    Comprehensive investigations of aluminum nanopowders, multi-walled carbon nanotubes, and aluminum mixtures with multi-walled carbon nanotubes subjected to ultrasonic deagglomeration in a liquid medium were performed, using microstructural, X-ray diffraction, thermogravimetric, and calorimetric analyses, and specific surface area measurements. The regime of ultrasonic deagglomeration of aluminum nanopowders with multi-walled carbon nanotubes in a liquid medium is described, during which the division of large agglomerates and creation of homogeneous distribution of mixtures components in the volume takes place. It was determined that ultrasonic treatment influences the morphology and crystalline structure of investigated mixtures, contributes to the appearance of X-ray amorphous phase, decreases the specific surface area of the aluminum nanopowder from 13 to 12 m2/g, and increases the pore volume and average size from 0.04 to 0.06 cm3/g and from 12 to 19 nm, respectively. The size of coherently-diffracting domain was determined by the X-ray diffraction analysis is close to that estimated from the specific surface area and corresponds to average crystallites size in the materials under study.

  5. The surface modifications of multi-walled carbon nanotubes for multi-walled carbon nanotube/poly(ether ether ketone) composites

    NASA Astrophysics Data System (ADS)

    Cao, Zongshuang; Qiu, Li; Yang, Yongzhen; Chen, Yongkang; Liu, Xuguang

    2015-10-01

    The effects of surface modifications of multi-walled carbon nanotubes (MWCNTs) on the morphology, dynamic mechanical and tribological properties of multi-walled carbon nanotube/poly(ether ether ketone) (MWCNT/PEEK) composites have been investigated. MWCNTs were treated with mixed acids to obtain acid-functionalized MWCNTs. Then the acid-functionalized MWCNTs were modified with ethanolamine (named e-MWCNTs). The MWCNT/PEEK composites were prepared by a solution-blending method. A more homogeneous distribution of e-MWCNTs within the composites was found with scanning electron microscopy. Dynamic mechanical analysis demonstrated a clear increase in the storage modulus of e-MWCNT/PEEK composites because of the improved interfacial adhesion strength between e-MWCNTs and PEEK. Furthermore, the presence of e-MWCNTs caused an enhancement in the glass transition temperature of the composites. Wear tests have shown that the friction coefficient of e-MWCNT/PEEK composites decreased significantly during the test after the running-in period. This suggests that there is an obvious improvement in tribological properties of e-MWCNT/PEEK composites. Overall, the e-MWCNT/PEEK composites have exhibited improved properties and are promising for their applications in industry.

  6. 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.

  7. Direct current electrical and microwave properties of polymer-multiwalled carbon nanotubes composites

    NASA Astrophysics Data System (ADS)

    Mdarhri, A.; Carmona, F.; Brosseau, C.; Delhaes, P.

    2008-03-01

    We report the results of effective direct current (dc) resistivities and alternating current (ac) complex permittivity measurements carried out on two series of polymer/multiwalled (MW) carbon nanotube (CNT) composite samples as function of the CNTs volume fraction and temperature. The CNTs have typical aspect ratio over 100:1 and are quasiuniformly dispersed in two types of polymer host [epoxy and polystyrene (PS)-cobutyl acrylate latex] according transmission electron microscopy characterization. A percolation threshold occurs in the composites with the PS latex matrix when the CNT volume fraction is ≈0.012. In contrast, the set of resistivity data for samples containing epoxy resin as host matrix is not representative of an intrinsically percolation transition. Atomic force microscopy, coupled to the measurement of the local electric resistances, permits us to study the agglomerate distribution in both types of composites. The differences in morphology between the two series of polymer/MWCNTs are attributed to interface effects between the elongated filler nanoparticles and the polymer chains. Comparison of the measured effective dc and ac resistivities, at temperatures ranging from 30to300K, with Sheng's model supports the fact that charge transport in the composites follows a thermal fluctuation induced tunneling mechanism, in which the tunneling of the electrons through the thermally induced fluctuating potential barrier formed by a thin insulating polymer layer separating MWCNTs aggregates. The spectral behavior of permittivity is consistent with a power-law form. Several mixing laws were tested to represent the filler fraction dependence of the effective permittivity in the microwave range of frequencies; however, none of them is able to quantitatively describe the sets of data. The basic deficiency of these formulas is that they make no explicit reference to the internal length scales in the composite samples.

  8. 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.

  9. Selective Electrochemical Detection of Ciprofloxacin with a Porous Nafion/Multiwalled Carbon Nanotube Composite Film Electrode.

    PubMed

    Gayen, Pralay; Chaplin, Brian P

    2016-01-27

    This study focuses on the development of electrochemical sensors for the detection of Ciprofloxacin (CFX) in natural waters and wastewater effluents. The sensors are prepared by depositing a layer of multiwalled carbon nanotubes (MWCNTs) dispersed in a porous Nafion film on to a boron-doped diamond (BDD) electrode substrate. The porous-Nafion-MWCNT/BDD electrode enhanced detection of CFX due to selective adsorption, which was accomplished by a combination of electrostatic attraction at -SO3(-) sites in the porous Nafion film and the formation of charge assisted hydrogen bonding between CFX and -COOH MWCNT surface functional groups. By contrast, the bare BDD electrode did not show any activity for CFX oxidation. The sensors were selective for CFX detection in the presence of other antibiotics (i.e., amoxicillin) and other nontarget water constituents (i.e., Cl(-), Ca(2+), humic acid, sodium dodecylbenzenesulfonate, salicylic acid, 4-aminobenzoic acid, and 4-hydroxybenzoic acid). A limit of detection of 5 nM (S/N = 5.04 ± 0.26) in a 0.1 M KH2PO4 supporting electrolyte (pH = 4.5) was obtained using differential pulse voltammetry. The linear dynamic ranges with respect to CFX concentration were 0.005-0.05 μM and 0.05-10 μM, and the sensitivities were 41 ± 5.2 μA μM(-1) and 2.1 ± 0.22 μA μM(-1), respectively. Sensor fouling was observed at high concentrations of some organic compounds such as 1 mM 4-aminobenzoic acid and 4-hydroxybenzoic acid. However, a short cathodic treatment fully restores sensor response. The results indicate that these sensors have application in detecting CFX in natural waters and wastewater effluents.

  10. 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.

  11. 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.

  12. Catalyst-free fabrication of graphene nanosheets without substrates using multiwalled carbon nanotubes and a spark plasma sintering process.

    PubMed

    Ham, Heon; Park, No-Hyung; Kang, Inpil; Kim, Hyoun Woo; Shim, Kwang Bo

    2012-07-07

    Catalyst-free graphene nanosheets without substrates were synthesized using pure solid carbon sources of multiwalled carbon nanotubes (MWCNTs) and a spark plasma sintering (SPS) process. Single and few-hundred-nanometer graphene nanosheets were formed from gas-phase carbon atoms which were directly evaporated from MWCNTs at a local high temperature.

  13. Pyrrole-based poly(ionic liquids) as efficient stabilizers for formation of hollow multi-walled carbon nanotubes particles.

    PubMed

    Chatterjee, Prithwish; Nofen, Elizabeth M; Xu, Wenwen; Hom, Conrad; Jiang, Hanqing; Dai, Lenore L

    2017-10-15

    Poly(ionic liquid) (PIL) derivatives with pyrrole intrinsically conducting polymer (ICP) backbones were synthesized and utilized as novel dispersants of multi-walled carbon nanotubes (MWCNTs) in various aqueous and non-aqueous systems, including polar and nonpolar solvents. This is due to the highly tunable nature of the PIL, in which the PILs of varying polarity with the same pyrrole-based polycation can be synthesized. The dispersions are exceedingly stable over many months, and with the addition of hexane, Pickering (solid-stabilized) emulsions with the PIL-stabilized MWCNTs at the droplet interfaces were formed. Depending on the hydrophobicity of the PIL, hexane-in-water and hexane-in-acetonitrile emulsions were formed, the latter marking the first non-aqueous CNT-stabilized emulsions, further advancing the processability of CNTs. The PIL-stabilized CNT Pickering emulsion droplets generated hollow conductive particles by subsequent drying of the emulsions. With emulsion templating, the hollow shells could be used as a payload carrier, depending on the solubility of the payload in the droplet phase of the emulsion. This was demonstrated with silicon nanoparticles, which have limited dispersibility in aqueous environments, but great scientific interest due to their potential electrochemical applications. Overall, this work explored a new class of efficient PIL-ICP hybrid stabilizers with tunable hydrophobicity, with hollow particle formation capability. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Multi-walled carbon nanotubes and poly(lactic acid) nanocomposite fibrous membranes prepared by solution blow spinning.

    PubMed

    Oliveira, Juliano E; Zucolotto, Valtencir; Mattoso, Luiz H C; Medeiros, Eliton S

    2012-03-01

    Nanocomposite fibers based on multi-walled carbon nanotubes (MWCNT) and poly(lactic acid) (PLA) were prepared by solution blow spinning (SBS). Fiber morphology was characterized by scanning electron microscopy (SEM) and optical microscopy (OM). Electrical, thermal, surface and crystalline properties of the spun fibers were evaluated, respectively, by conductivity measurements (4-point probe), thermogravimetric analyses (TGA), differential scanning calorimetry (DSC), contact angle and X-ray diffraction (XRD). OM analysis of the spun mats showed a poor dispersion of MWCNT in the matrix, however dispersion in solution was increased during spinning where droplets of PLA in solution loaded with MWCNT were pulled by the pressure drop at the nozzle, producing PLA fibers filled with MWCNT. Good electrical conductivity and hydrophobicity can be achieved at low carbon nanotube contents. When only 1 wt% MWCNT was added to low-crystalline PLA, surface conductivity of the composites increased from 5 x 10(-8) to 0.46 S/cm. Addition of MWCNT can slightly influence the degree of crystallinity of PLA fibers as studied by XRD and DSC. Thermogravimetric analyses showed that MWCNT loading can decrease the onset degradation temperature of the composites which was attributed to the catalytic effect of metallic residues in MWCNT. Moreover, it was demonstrated that hydrophilicity slightly increased with an increase in MWCNT content. These results show that solution blow spinning can also be used to produce nanocomposite fibers with many potential applications such as in sensors and biosensors.

  15. Binding energy and mechanical stability of single- and multi-walled carbon nanotube serpentines.

    PubMed

    Zhao, Junhua; Lu, Lixin; Rabczuk, Timon

    2014-05-28

    Recently, Geblinger et al. [Nat. Nanotechnol. 3, 195 (2008)] and Machado et al. [Phys. Rev. Lett. 110, 105502 (2013)] reported the experimental and molecular dynamics realization of S-like shaped single-walled carbon nanotubes (CNTs), the so-called CNT serpentines. We reported here results from continuum modeling of the binding energy γ between different single- and multi-walled CNT serpentines and substrates as well as the mechanical stability of the CNT serpentine formation. The critical length for the mechanical stability and adhesion of different CNT serpentines are determined in dependence of EiIi, d, and γ, where EiIi and d are the CNT bending stiffness and distance of the CNT translation period. Our continuum model is validated by comparing its solution to full-atom molecular dynamics calculations. The derived analytical solutions are of great importance for understanding the interaction mechanism between different single- and multi-walled CNT serpentines and substrates.

  16. 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.

  17. 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

  18. Silica-coated multi-walled carbon nanotubes impregnated with polyethyleneimine for carbon dioxide capture under the flue gas condition

    NASA Astrophysics Data System (ADS)

    Lee, Min-Sang; Park, Soo-Jin

    2015-03-01

    In this study, silica-coated multi-walled carbon nanotubes impregnated with polyethyleneimine (PEI) were prepared via a two-step process: (i) hydrolysis of tetraethylorthosilicate onto multi-walled carbon nanotubes, and (ii) impregnation of PEI. The adsorption properties of CO2 were investigated using CO2 adsorption-desorption isotherms at 298 K and thermogravimetric analysis under the flue gas condition (15% CO2/85% N2). The results obtained in this study indicate that CO2 adsorption increases after impregnation of PEI. The increase in CO2 capture was attributed to the affinity between CO2 and the amine groups. CO2 adsorption-desorption experiments, which were repeated five times, also showed that the prepared adsorbents have excellent regeneration properties.

  19. Multi-walled carbon nanotubes (MWCNT) as compliant electrodes for dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Chua, Soo-Lim; Neo, Xin-Hui; Lau, Gih-Keong

    2011-04-01

    A stacked dielectric elastomer actuator (DEA) consists of multiple layers of elastomeric dielectrics interleaved with compliant electrodes. It is capable of taking a tensile load if only the interleaving compliant electrodes provide a good bonding and enough elasticity. However, the stacked configuration of DEA was found to produce less actuation strain as compared to a single-layer configuration of pre-stretched membrane. It is believed the binder for compliant electrodes has a significant influence on the actuation strain. Yet, there has yet systematic study on the effect of binder. In this paper, we will study the effects of binder, solvent, and surface fictionalization on the compliant electrodes using the conductive filler of Multi-Walled Carbon Nanotube (MWCNT). Two types of binders are used, namely a soft silicone rubber (Mold Max 10T) and a soft silicone gel (Sylgard 527 gel). The present experiments show that the actuators using binders in the compliant electrodes produce a much lower areal strain as compared to the ones without binders in them. It is found that introducing a binder in the electrodes decreases the conductivity. The MWCNT compliant electrode with binder remains conductive (<1TΩ) up to a strain of 300%, whereas the one without binder remains conductive up to a strain of 800%. Changing the type of binder to a softer and less-viscous one increases the percolation ratio for MWCNT-COOH filler from 5% to 15% but this does not significantly increase the actuation strain. In addition, this study investigates the effect of MWCNT functionalization on the dielectric elastomeric actuation. The compliant electrodes using the MWCNT functionalized with (-COOH) group was also found to have a lower electrical conductivity and areal actuation strain, in comparison to the ones using the pristine MWCNT filler. In addition to binder, solvent for dispersing MWCNT-COOH was found to affect the actuation strain even though the solvent is eventually removed by

  20. 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...

  1. Composites of polyvinyl alcohol and carbon (coils, undoped and nitrogen doped multiwalled carbon nanotubes) as ethanol, methanol and toluene vapor sensors.

    PubMed

    Greenshields, Márcia W C C; Hümmelgen, Ivo A; Mamo, Messai A; Shaikjee, Ahmed; Mhlanga, Sabelo D; van Otterlo, Willem A L; Coville, Neil J

    2011-11-01

    We investigate the chemical sensing behavior of composites prepared with polyvinyl alcohol and carbon materials (undoped multiwalled carbon nanotubes, nitrogen-doped multiwalled carbon nanotubes and carbon nanocoils). We determine the sensitivity of thin films of these composites for ethanol, methanol and toluene vapor, comparing their conductance and capacitance responses. The composite that exhibits highest sensitivity depends on specific vapor, vapor concentration and measured electrical response, showing that the interactivity of the carbon structure with chemical species depend on structural specificities of the carbon structure and doping.

  2. 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.

  3. 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.

  4. Effect of Undensified Silica Fume on the Dispersion of Carbon Nanotubes within a Cementitious Composite

    NASA Astrophysics Data System (ADS)

    Alrekabi, S.; Cundy, A.; Whitby, Raymond L. D.; Lampropoulos, A.; Savina, I.

    2017-04-01

    The synergistic effect of multi-walled carbon nanotubes (MWCNTs) and Undensified Silica Fume (USF) on the microstructure of cementitious composites has been studied. In the current work, USF was used to enhance the dispersion of nanotubes throughout the composite and prevent the re-agglomeration of nanotubes by providing a physical barrier of particles of small size. Ultrasonication was employed to disperse MWCNTs in water in the presence of polycarboxylate-based superplasticizer (PCE) as a dispersion agent. The results indicate that incorporation of USF considerably improves the dispersion of nanotubes in the composites, with subsequent enhancement of composite packing density. This enhancement can be attributed to the synergistic effect of MWCNTs and USF in reducing the volume of pores through the cementitious composites.

  5. Surface charge and cellular processing of covalently functionalized multiwall carbon nanotubes determine pulmonary toxicity.

    PubMed

    Li, Ruibin; Wang, Xiang; Ji, Zhaoxia; Sun, Bingbing; Zhang, Haiyuan; Chang, Chong Hyun; Lin, Sijie; Meng, Huan; Liao, Yu-Pei; Wang, Meiying; Li, Zongxi; Hwang, Angela A; Song, Tze-Bin; Xu, Run; Yang, Yang; Zink, Jeffrey I; Nel, André E; Xia, Tian

    2013-03-26

    Functionalized carbon nanotubes (f-CNTs) are being produced in increased volume because of the ease of dispersion and maintenance of the pristine material physicochemical properties when used in composite materials as well as for other commercial applications. However, the potential adverse effects of f-CNTs have not been quantitatively or systematically explored. In this study, we used a library of covalently functionalized multiwall carbon nanotubes (f-MWCNTs), established from the same starting material, to assess the impact of surface charge in a predictive toxicological model that relates the tubes' pro-inflammatory and pro-fibrogenic effects at cellular level to the development of pulmonary fibrosis. Carboxylate (COOH), polyethylene glycol (PEG), amine (NH2), sidewall amine (sw-NH2), and polyetherimide (PEI)-modified MWCNTs were successfully established from raw or as-prepared (AP-) MWCNTs and comprehensively characterized by TEM, XPS, FTIR, and DLS to obtain information about morphology, length, degree of functionalization, hydrodynamic size, and surface charge. Cellular screening in BEAS-2B and THP-1 cells showed that, compared to AP-MWCNTs, anionic functionalization (COOH and PEG) decreased the production of pro-fibrogenic cytokines and growth factors (including IL-1β, TGF-β1, and PDGF-AA), while neutral and weak cationic functionalization (NH2 and sw-NH2) showed intermediary effects. In contrast, the strongly cationic PEI-functionalized tubes induced robust biological effects. These differences could be attributed to differences in cellular uptake and NLRP3 inflammasome activation, which depends on the propensity toward lysosomal damage and cathepsin B release in macrophages. Moreover, the in vitro hazard ranking was validated by the pro-fibrogenic potential of the tubes in vivo. Compared to pristine MWCNTs, strong cationic PEI-MWCNTs induced significant lung fibrosis, while carboxylation significantly decreased the extent of pulmonary fibrosis. These

  6. Lung burdens and kinetics of multi-walled carbon nanotubes (Baytubes) are highly dependent on the disaggregation of aerosolized MWCNT.

    PubMed

    Pauluhn, Jürgen; Rosenbruch, Martin

    2015-03-01

    Previous repeated inhalation exposure studies on rats with multi-walled carbon nanotubes (MWCNT, Baytubes®) suggested that their pulmonary toxicity was predominated by the morphology and density of the aggregated structure. Evidence of any disintegration of these structures in the lung did not exist. The objective of this study was to study as to which extent the formulation of pristine MWCNT as wet-dispersion changes the morphology of assemblage structures in the presence of disintegrated sub-structures. The focus was on the comparative inhalation dosimetry and kinetics of dry- and wet-dispersed Baytubes to better understand the cause of putative differences in pulmonary toxicity originating from pristine and rigorously formulated MWCNT. Rats were nose-only exposed to dry-dispersed and wet-dispersed Baytubes for 6-h at 25-30 mg/m(3). Aerodynamic particle size measurements demonstrate substantial differences in the particle size of dry- (MMAD 2.6 µm) and wet-dispersed (MMAD 0.8 µm) MWCNT. Time-course changes of MWCNT retained in the lung were examined during a post-exposure period of 3 months. Lung burdens were analytically determined in digested lungs using the EC/OC total carbon method. Dosimetry was complemented by light and transmission electron microscopy (TEM) of MWCNT retained in alveolar macrophages (AM). As a result, the initially deposited pulmonary dose of MWCNT was three times higher following wet-dispersed MWCNT at essentially similar inhalation chamber concentrations. The elimination half-time of dry- and wet-dispersed MWCNT was 87 and 46 d, respectively. TEM provided evidence that wet-dispersed MWCNT were inhaled as disintegrated structures with distribution-patterns within the cytoplasm of AMs that differed appreciably from those of dry-dust exposed animals. In summary, this study shows that specialized technical processes to formulate MWCNT may have dramatic consequences on their pulmonary fate and associated toxicity. Such properties can only

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  8. 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.

  9. 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...

  10. Facile synthesis of highly aligned multiwalled carbon nanotubes from polymer precursors.

    SciTech Connect

    Han, C. Y.; Xiao, Z.-L.; Wang, H. H.; Lin, X.-M.; Trasobares, S.; Cook, R. E.; Richard J. Daley Coll.; Northern Illinois Univ.; Univ. de Cadiz

    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 carbon 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.

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

    SciTech Connect

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

    2007-08-27

    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

  12. Distinct electrical effects of multi-walled carbon nanotubes in two composites

    NASA Astrophysics Data System (ADS)

    Wang, Leizhi; Wang, Hua; Datta, Timir; Yin, Ming; Tian, Xingyou

    2014-11-01

    The temperature dependent conductivity of multi-walled carbon nanotube film (MWNT) is reported and the different electrical properties of nanotubes in two composites are compared. Due to the disordered structures, our carbon nanotube film displays variable range hopping behavior. While the geometric distributions of carbon nanotubes in the conducting polyaniline (PANI) and insulating polyamide (PA66) are similar, charge carriers transport distinctly. The conductive PANI, following one-dimensional variable range hopping, dominates the electrical properties of MWNT/PANI composites. The effect of MWNTs becomes prominent only at low temperature range. However, the contact junctions composed by adjacent carbon nanotubes, instead of nanotubes themselves or the polymer matrix, determine the electrical properties of MWNT/PA66 composites, showing the fluctuation induced tunneling characteristic.

  13. 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.

  14. 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.

  15. Blackbody radiation from resistively heated multiwalled carbon nanotubes during field emission

    NASA Astrophysics Data System (ADS)

    Sveningsson, M.; Jonsson, M.; Nerushev, O. A.; Rohmund, F.; Campbell, E. E. B.

    2002-08-01

    We report the observation of blackbody radiation from aligned multiwalled carbon nanotubes undergoing field emission. The light intensity correlates with fluctuations in the emission current. The onset of light emission occurs at an emission current of 1 mA/cm2 and corresponds to a temperature on the order of 1550 K. Beyond this critical current irreversible changes occur in the nanotube film. The correlation between light intensity and emission current provides convincing evidence for Joule heating and stable operation for nanotube temperatures up to at least 2000 K and emission current densities on the order of 10 mA/cm2.

  16. Adsorption kinetics, isotherms and thermodynamics of atrazine on surface oxidized multiwalled carbon nanotubes.

    PubMed

    Chen, Guang-Cai; Shan, Xiao-Quan; Zhou, Yi-Quan; Shen, Xiu-e; Huang, Hong-Lin; Khan, Shahamat U

    2009-09-30

    The adsorption kinetics, isotherms and thermodynamic of atrazine on multiwalled carbon nanotubes (MWCNTs) containing 0.85%, 2.16%, and 7.07% oxygen was studied. Kinetic analyses were performed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The regression results showed that the pseudo-second-order law fit the adsorption kinetics. The calculated thermodynamic parameters indicated that adsorption of atrazine on MWCNTs was spontaneous and exothermic. Standard free energy (DeltaG(0)) became less negative when the oxygen content of MWCNTs increased from 0.85% to 7.07% which is consistent with the low adsorption affinity of MWCNTs for atrazine.

  17. Direct evaluation of ballistic phonon transport in a multi-walled carbon nanotube

    SciTech Connect

    Hayashi, Hiroyuki; Takahashi, Koji; Ikuta, Tatsuya; Nishiyama, Takashi; Takata, Yasuyuki; Zhang, Xing

    2014-03-17

    Phonon confinement and in situ thermal conductance measurements in an individual multi-walled carbon nanotube (MWNT) are reported. Focused ion beam (FIB) irradiation was used to successively shorten a 4.8 μm long MWNT, eventually yielding a 0.3 μm long MWNT. After the first FIB irradiation, a 41% reduction in conductance was achieved, compared with that of the pristine MWNT. This was because the contributions from phonons with long free paths were excluded by scattering at FIB-induced defects. Phonon transport in linked multiple-length nanotubes was also investigated.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Preparation and biodistribution of tyrosine modified multiwall carbon nanotubes.

    PubMed

    Liang, Geyu; Zhang, Tao; Liu, Ran; Ye, Bing; Yin, Lihong; Pu, Yuepu

    2010-12-01

    The functional modification of the outer surface of carbon nanotubes (CNTs) is likely to improve their biocompatibility. Therefore, CNTs have attracted great attention not only in electrical, optical and mechanical applications but also in biological and pharmaceutical applications. Thus, it is important to examine the biodistribution and kinetics of the carbon-based nanotubes when they are introduced into living systems. Here, we synthesized and characterized tyrosine-functionalized carbon nanotubes (CNTs-Tyr), and assessed the biodistribution profile of CNTs-Tyr in mice, following three different administrations by the 125I radioisotope tracer method. CNTs-Tyr was delivered quickly around the entire body, and different absorbtion and biodistribution profiles of CNTs-Tyr were observed with different routes of administration. Following intravenous injection, CNTs-Tyr accumulated within 24 h mainly in the lungs and slightly in the spleen and liver, and may be eliminated primarily through the kidneys. After administration via gavage, most of the CNTs-Tyr were eliminated through the intestine, and rarely delivered into the organs. After intraperitoneal injection, CNTs-Tyr accumulated in the spleen and were rapidly eliminated from the other organs within 24 h. The blood circulation half-life of CNTs-Tyr was about 4.4 h. The behavior of CNTs-Tyr in mice is somewhat different from the results reported previously. This suggests that the functionalized group may affect the affinity of carbon nanotubes for particular organs. The results provide basic biological information for the biomedical application and risk assessment of CNTs.

  3. 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.

  4. 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.

  5. 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%.

  6. Electronic structure of fluorinated multiwalled carbon nanotubes studied using x-ray absorption and photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Brzhezinskaya, M. M.; Muradyan, V. E.; Vinogradov, N. A.; Preobrajenski, A. B.; Gudat, W.; Vinogradov, A. S.

    2009-04-01

    This paper presents the results of combined investigation of the chemical bond formation in fluorinated multiwalled carbon nanotubes (MWCNTs) with different fluorine contents (10-55wt%) and reference compounds (highly oriented pyrolytic graphite crystals and “white” graphite fluoride) using x-ray absorption and photoelectron spectroscopy at C1s and F1s thresholds. Measurements were performed at BESSY II (Berlin, Germany) and MAX-laboratory (Lund, Sweden). The analysis of the soft x-ray absorption and photoelectron spectra points to the formation of covalent chemical bonding between fluorine and carbon atoms in the fluorinated nanotubes. It was established that within the probing depth (˜15nm) of carbon nanotubes, the process of fluorination runs uniformly and does not depend on the fluorine concentration. In this case, fluorine atoms interact with MWCNTs through the covalent attachment of fluorine atoms to graphene layers of the graphite skeleton (phase 1) and this bonding is accompanied by a change in the hybridization of the 2s and 2p valence electron states of the carbon atom from the trigonal (sp2) to tetrahedral (sp3) hybridization and by a large electron transfer between carbon an fluorine atoms. In the MWCNT near-surface region the second fluorine-carbon phase with weak electron transfer is formed; it is located mainly within two or three upper graphene monolayers, and its contribution becomes much poorer as the probing depth of fluorinated multiwalled carbon nanotubes (F-MWCNTs) increases. The defluorination process of F-MWCNTs on thermal annealing has been investigated. The conclusion has been made that F-MWCNT defluorination without destruction of graphene layers is possible.

  7. Retention and transport of multi-walled carbon nanotubes in saturated porous media: Effect of inflow concentration and solution chemistry

    NASA Astrophysics Data System (ADS)

    Sharma, Prabhakar; Sundra Pandian, Rajaveni; Sumadevi Nair, Indu

    2013-04-01

    Carbon nanotubes (CNTs) have been one of the widely manufactured nanoparticles which incorporate into various consumer products, such as bicycle frame, tennis racket, and other biomedical applications. After its increased production and use in several products, CNTs may create a potential environmental risk to soil and groundwater system. It is therefore essential to improve the current understanding of environmental fate and transport of CNTs at an extreme subsurface condition. It is possible that the nanoparticle can aggregate or deposit at the solid surfaces at different background chemistry and nanoparticle concentration while moving into the porous media. The current study systematically investigates the effect of inflow concentration of functionalized multi-walled carbon nanotubes (MWCNTs) on change in retention on the solid surfaces using a series of column experiments under fully saturated condition. A one-dimensional convection-dispersion model incorporated with collector efficiency for cylindrical nanoparticles was used to simulate the transport of MWCNTs in porous media. The result showed that higher particle number concentration led to higher relative retention. It is caused by possible aggregation within the soil pores but not influenced by greater surface coverage due to higher inflow concentration.

  8. Functionalized Multi-Wall Carbon Nanotubes Enhance Transfection and Expression Efficiency of Plasmid DNA in Fish Cells.

    PubMed

    Liu, Guanglu; Wang, Yuan; Hu, Yang; Yu, Xiaobo; Zhu, Bin; Wang, Gaoxue

    2016-03-03

    DNA vaccines are considered to be the most promising method against infectious diseases in the aquaculture industry. In the present study, we investigated the potency of ammonium group-functionalized multi-walled carbon nanotubes (MWCNTs) in enhancing the transfection and expression efficiency of plasmid DNA (pEGFP-vp5) in Ctenopharyngodon idellus kidney (CIK) cells. Agarose gel shift assay results show that ammonium group-functionalized carbon nanotubes are able to condense DNA in varying degrees. Scanning electron microscope (SEM) images shows that CIK cells show a great affinity for MWCNTs-NH₃⁺ and the CNTs covering the cell surface tend to orient their tips perpendicularly to the cell surface, and appear to be "needle-pricking the cells". Transmission electron microscope (TEM) images confirmed that MWCNTs-NH₃⁺ penetrate the cell membranes and are widely dispersed in the CIK cell. Real-time PCR was used to detect the transfection efficiency through the expression of the outer capsid protein (VP5). The results showed that the MWCNTs-NH₃⁺:DNA complexes are able to transfect CIK cells effectively at different charge ratio than naked DNA. Subsequent studies confirmed that both functional groups and charge ratio are important factors that determine the transfection efficiency of plasmid DNA. All these results indicated that MWCNTs-NH₃⁺:DNA complexes could be suitable for developing DNA vaccine for the control of virus infection in the aquaculture industry.

  9. 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

  10. 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

  11. A new material with atomized cobalt-multiwalled carbon nanotubes: a possible substitute for human implants.

    PubMed

    Joshi, Bharat; Gupta, Sachin; Kalra, Nitin; Gudyka, Russell; Santhanam, K S V

    2010-06-01

    A new material composed of atomized cobalt-multiwalled carbon nanotube has been produced and characterized by thermogravimetric analysis and polarization studies to estimate its lifetime. This does not show cobalt thermal oxidation suggesting that it is confined inside the carbon nanotube matrix. The density functional calculations in the literature predict a strong interaction leading to higher hybridization of cobalt atom and carbon nanotubes. A detailed investigation of the corrosion measurements shows that the new material of thickness 0.8 mm, 1 mm, 1.5 mm and 2 mm would last for 31, 39, 60 and 79 years and it would substitute with cobalt-chromium alloy that is used as a load bearing implant for patients with knee pain or partial denture implant.

  12. 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

  13. 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.

  14. 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...

  15. Polyamidoamine-grafted multiwalled carbon nanotubes for gene delivery: synthesis, transfection and intracellular trafficking.

    PubMed

    Liu, Min; Chen, Biao; Xue, Yanan; Huang, Jie; Zhang, Liming; Huang, Shiwen; Li, Qingwen; Zhang, Zhijun

    2011-11-16

    Functionalized multiwalled carbon nanotubes (f-MWNTs) are of great interest and designed as a novel gene delivery system. In this paper, we presented synthesis of polyamidoamine-functionalized multiwalled carbon nanotubes (PAA-g-MWNTs) and their application as a novel gene delivery system. The PAA-g-MWNTs, obtained from amide formation between PAA and chemically oxidized MWNTs, were stable in aqueous solution and much less toxic to cells than PAA and PEI 25KDa. More importantly, PAA-g-MWNTs showed comparable or even higher transfection efficiency than PAA and PEI at optimal w/w ratio. Intracellular trafficking of Cy3-labeled pGL-3 indicated that a large number of Cy3-labeled pGL-3 were attached to nucleus membrane, the majority of which was localized in nucleus after incubation with cells for 24 h. We have demonstrated that PAA modification of MWNTs facilitate higher DNA uptake and gene expression in vitro. All these facts suggest potential application of PAA-g-MWNTs as a novel gene vector with high transfection efficiency and low cytotoxicity.

  16. A novel nanocomposite from multiwalled carbon nanotubes functionalized with a conducting polymer

    NASA Astrophysics Data System (ADS)

    Philip, Biju; Xie, Jining; Chandrasekhar, Anupama; Abraham, Jose; Varadan, Vijay K.

    2004-04-01

    A nanocomposite of a multiwalled carbon nanotube and polythiophene was prepared by functionalizing the nanotube surface with a polythiophene, poly[3-(2-hydroxyethyl)-2,5-thienylene], containing pendant hydroxyl groups. The composite was characterized by IR, high resolution TEM and conductivity measurements. The poly[3-(2-hydroxyethyl)-2,5-thienylene] (PHET) was synthesized by the oxidation polymerization of 2-(3-thienylethanol) using FeCl3 and CHCl3. Multiwalled carbon nanotubes were synthesized by a microwave CVD method and oxidized with potassium permanganate using a phase transfer catalyst in mild conditions. The COOH groups formed on the nanotube surface were converted to COCl using thionyl chloride and it was then condensed with the polythiophene at high temperature in anhydrous DMF. High resolution TEM images showed that the functionalization provided a firm coating of the conducting polymer on nanotube walls. This nanocomposite with PHET grafted to CNT showed higher conductivity than a nanocomposite of PHET and CNT in the same percentage weight composition prepared by ultrasonic mixing of the two. Such a material was designed and synthesized with a view to electronic and sensor applications.

  17. 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.

  18. Multiwalled carbon nanotube films as small-sized temperature sensors

    NASA Astrophysics Data System (ADS)

    Di Bartolomeo, A.; Sarno, M.; Giubileo, F.; Altavilla, C.; Iemmo, L.; Piano, S.; Bobba, F.; Longobardi, M.; Scarfato, A.; Sannino, D.; Cucolo, A. M.; Ciambelli, P.

    2009-03-01

    We present the fabrication of thick and dense carbon nanotube networks in the form of freestanding films (CNTFs) and the study of their electric resistance as a function of the temperature, from 4 to 420 K. A nonmetallic behavior with a monotonic R(T ) and a temperature coefficient of resistance around -7×10-4 K-1 is generally observed. A behavioral accordance of the CNTF conductance with the temperature measured by a solid-state thermistor (ZnNO, Si, or Pt) is demonstrated, suggesting the possibility of using CNTFs as temperature small-sized (freely scalable) sensors, besides being confirmed by a wide range of sensitivity, fast response, and good stability and durability. Concerning electric behavior, we also underline that a transition from nonmetal to metal slightly below 273 K has been rarely observed. A model involving regions of highly anisotropic metallic conduction separated by tunneling barrier regions can explain the nonmetallic to metallic crossover based on the competing mechanisms of the metallic resistance rise and the barrier resistance lowering.

  19. 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.

  20. 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.

  1. Experimental investigation on effect of multi-walled carbon nanotubes concentration on flexural properties and microstructure of cement mortar composite

    NASA Astrophysics Data System (ADS)

    Yousefi, Ali; Bunnori, Norazura Muhamad; Khavarian, Mehrnoush; Hassanshahi, Omid; Majid, Taksiah A.

    2017-10-01

    Multi-walled carbon nanotubes (MWCNTs) with extraordinary properties have shown a promising role toward enhancing the flexural performance of cement composites. This paper investigates the effect of concentrations of MWCNTs on major flexural properties of cement mortar composites, including flexural strength, strain capacity, modulus of toughness, and modulus of elasticity. For this purpose, cement mortar reinforced with various concentrations of MWCNTs (0.02, 0.05, and 0.1 wt.% by weight of cement). Dispersion of MWCNTs was carried out using ultrasonic energy and concrete superplasticizer as surfactant agent. Prismatic beams of sizes 100 mm×100 mm×500 mm were fabricated and four-point bending tests were performed on the beam specimens at the age of 28 days. The results from bending tests indicated substantial improvements in the flexural strength, strain capacity and modulus of toughness of MWCNT-cement mortar, while the modules of elasticity remained constant. It was observed that specimens reinforced with 0.05 wt.% of MWCNTs exhibited higher flexural properties enhancement. Besides, it was noticed that with the increase of MWCNTs content, the flexural properties of MWCNT-cement mortar increased. The microstructure observation of MWCNT-cement mortar demonstrated well dispersion of nanotubes with concentration of 0.05 wt.% but large agglomerates and bundles of MWCNTs depicted within the sample with higher loading of MWCNTs (0.1 wt.%). It was concluded that the properties enhancement of MWCNT-cement composites highly depends on the concentration of MWCNTs and the level of dispersion of nanotubes in the cement matrix.

  2. Epoxy elastomers reinforced with functionalized multi-walled carbon nanotubes as stimuli-responsive shape memory materials

    SciTech Connect

    Lama, G. C.; Nasti, G.; Cerruti, P.; Gentile, G.; Carfagna, C.; Ambrogi, V.

    2014-05-15

    In this work, the incorporation of multiwalled carbon nanotubes (MWCNT) into epoxy-based elastomers was carried out in order to obtain nanocomposite systems with shape memory effect. For the preparation of elastomeric matrices, p-bis(2,3-epoxypropoxy)-α-methylstilbene (DOMS) was cured with sebacic acid. DOMS was synthesized in our laboratory and it is characterized by a rigid-rod, potentially liquid crystalline structure. A lightly cross-linked liquid crystalline elastomer was obtained. As for nanocomposites, variable amounts (0.75, 1.50, 3.0, 6.0, 12.0 wt.%) of COOH-MWCNTs were employed. In order to improve the nanotubes dispersibility and the interfacial adhesion with the epoxy matrix, an optimized two-step procedure was developed, which consisted in grafting the epoxy monomer onto the nanotube surface and then curing it in presence of crosslinking agent. DOMS-functionalized MWCNT were characterized through solvent dispersion experiments, FTIR spectroscopy and TGA analysis, which demonstrated the occurred covalent functionalization of the nanotubes with the epoxy monomers. The morphological analysis through electron microscopy demonstrated that this was an efficient strategy to improve the dispersion of nanotubes within the matrix. The second part of the work was devoted to the structural, thermal, mechanical and electric characterization of elastomeric nanocomposites. The results indicated a general improvement of properties of nanocomposites. Also, independently of the nanotube content, a smectic phase formed. Shape memory features of LC systems were also evaluated. It was demonstrated the shape could be recovered through heating, solvent immersion, as well as upon the application of an electrical field.

  3. 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.

  4. Molecular photoeffect in single- and multi-wall carbon nanotubes with physisorbed oxygen molecules

    NASA Astrophysics Data System (ADS)

    Geru, I. I.

    2017-12-01

    The EPR spectra of high purity single-walled and multi-walled semiconducting carbon nanotubes exhibit wide resonance lines (154 ± 5 mT and 159 ± 5 mT, respectively, at room temperature). The broadening of EPR lines is due to magnetic dipole-dipole interaction with the spin-triplet ground state oxygen molecules physisorbed on the carbon nanotubes surface. Here we show that the emission of O2 molecules occurs under the photons with energy of 2.33 eV that leads to narrowing of the EPR line. The number of molecules emitted from nanotubes is proportional to the flux of incident radiation, in full analogy with the first law of the classical photoelectric effect.

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

    PubMed Central

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

    2012-01-01

    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. PMID:22754296

  6. Conductivity enhancement of multiwalled carbon nanotube thin film via thermal compression method

    NASA Astrophysics Data System (ADS)

    Tsai, Wan-Lin; Wang, Kuang-Yu; Chang, Yao-Jen; Li, Yu-Ren; Yang, Po-Yu; Chen, Kuan-Neng; Cheng, Huang-Chung

    2014-08-01

    For the first time, the thermal compression method is applied to effectively enhance the electrical conductivity of carbon nanotube thin films (CNTFs). With the assistance of heat and pressure on the CNTFs, the neighbor multiwalled carbon nanotubes (CNTs) start to link with each other, and then these separated CNTs are twined into a continuous film while the compression force, duration, and temperature are quite enough for the reaction. Under the compression temperature of 400°C and the compression force of 100 N for 50 min, the sheet resistance can be reduced from 17 to 0.9 k Ω/sq for the CNTFs with a thickness of 230 nm. Moreover, the effects of compression temperature and the duration of thermal compression on the conductivity of CNTF are also discussed in this work.

  7. The effects of γ-irradiation dose on chemical modification of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Guo, Jinxue; Li, Yuguo; Wu, Shengwei; Li, Wenxin

    2005-10-01

    Multi-walled carbon nanotubes (MWNTs) irradiated with γ-rays were subjected to chemical modification with thionyl chloride and decylamine. Products from chemical treatment were characterized by both FTIR and Raman spectra. Element analysis (EA) and thermogravimetric analysis (TGA) for the modified soluble MWNTs (s-MWNTs) indicated that γ-radiation increased the concentration of functional groups bound to MWNTs, which arose due to the increasing number of defect sites created on the MWNTs by γ-photons. Compared with untreated MWNTs, γ-irradiation significantly enhanced the solubility of MWNTs in acetone and tetrahydrofuran (THF). We therefore conclude that γ-irradiation provides a novel approach to prepare various functionalized modifications of carbon nanotubes (CNTs).

  8. 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

  9. Spatial Frequency Heterodyne Imaging of Water Filled Multi-walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Schunk, Francisco; Rand, Danielle; Rose-Petruck, Christoph

    2015-03-01

    Evaporation and condensation of water on multi-walled carbon nanotube (MWCNT) surfaces was monitored as a function of both temperature and time using x-ray Spatial Frequency Heterodyne Imaging (SFHI). SFHI is an imaging method that produces an absorption and scatter image from a single exposure, with increased sensitivity to variations in electron density relative to more common place x-ray imaging techniques. Different features seen in the temporal scatter intensity profiles recorded during evaporation and condensation revealed the existence of an absorption-desorption hysteresis. Effects on the previously mentioned phenomena due to chemical functionalization of the carbon nanotube surfaces were also observed. Functionalization increased the interaction potential between the MWCNT walls and water molecules, altering the evaporation event time scale and increasing the temperature at which condensation could take place. The observed temperature dependent changes in evaporation time scales coincide with the boiling point for confined water predicted by the Kelvin equation.

  10. 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.

  11. Microstructure and mechanical properties of silicon carbide ceramics reinforced with multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Barmin, A.; Bortnikova, V.; Ivanov, A.; Kornev, V.; Lurie, S.; Solyaev, Y.

    2016-04-01

    A microstructure, a composition and mechanical properties of multi-walled carbon of nanotube-reinforced silicon carbide ceramics were examined. The amount of carbon nanotubes was up to 1% wt. Samples was prepared by spark plasma sintering. It has been found that the optimal sintering temperature is 2000°C with an exposure duration of 5 minutes and a pressure of 50 MPa. The effect of the CNT mass fraction on the Young modulus of silicon carbide ceramics composites was investigated for different temperatures and processing conditions of samples using ultrasonic techniques. It has been established that Young's modulus of ceramics decreases due to addition of CNT. Elastic properties of the composites cross section were characterized using nano-indentation. It has been revealed that the stiffness of the ceramics intergranular phase decreases due to addition of CNT.

  12. Ultraviolet laser treatment of multiwall carbon nanotubes grown at low temperature

    NASA Astrophysics Data System (ADS)

    Kim, J. S.; Ahn, K. S.; Kim, C. O.; Hong, J. P.

    2003-03-01

    Simple laser irradiation of well-aligned multiwall carbon nanotubes (MWCNTs) was performed to intentionally modify structural defects and to ablate possible contamination of the MWCNTs. Scanning electron microscopy and transmission electron microscopy confirmed the clear presence of the MWCNTs with open tips. A Raman spectra exhibited a decrease in an intensity ratio (ID/IG) of 1352 cm-1 (D band) over 1583 cm-1 (G band) peaks by significantly reducing the amorphous carbon phases of D band peaks. The structural improvement in the MWCNTs after optimum laser exposure resulted in a reduction of the turn-on voltage from 1.0 to 0.6 V/μm and an increase in the emission current.

  13. 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.

  14. Carbon nanotubes: measuring dispersion and length.

    PubMed

    Fagan, Jeffrey A; Bauer, Barry J; Hobbie, Erik K; Becker, Matthew L; Hight Walker, Angela R; Simpson, Jeffrey R; Chun, Jaehun; Obrzut, Jan; Bajpai, Vardhan; Phelan, Fred R; Simien, Daneesh; Huh, Ji Yeon; Migler, Kalman B

    2011-01-18

    Advanced technological uses of single-walled carbon nanotubes (SWCNTs) rely on the production of single length and chirality populations that are currently only available through liquid-phase post processing. The foundation of all of these processing steps is the attainment of individualized nanotube dispersions in solution. An understanding of the colloidal properties of the dispersed SWCNTs can then be used to design appropriate conditions for separations. In many instances nanotube size, particularly length, is especially active in determining the properties achievable in a given population, and, thus, there is a critical need for measurement technologies for both length distribution and effective separation techniques. In this Progress Report, the current state of the art for measuring dispersion and length populations, including separations, is documented, and examples are used to demonstrate the desirability of addressing these parameters. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    PubMed

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

    2018-01-18

    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.

  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. 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...

  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. 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...

  20. 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...

  1. 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

  2. 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.

  3. 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...

  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. In situ Polymerization of Multi-Walled Carbon Nanotube/Nylon-6 Nanocomposites and Their Electrospun Nanofibers

    PubMed Central

    2009-01-01

    Multiwalled carbon nanotube/nylon-6 nanocomposites (MWNT/nylon-6) were prepared by in situ polymerization, whereby functionalized MWNTs (F-MWNTs) and pristine MWNTs (P-MWNTs) were used as reinforcing materials. The F-MWNTs were functionalized by Friedel-Crafts acylation, which introduced aromatic amine (COC6H4-NH2) groups onto the side wall. Scanning electron microscopy (SEM) images obtained from the fractured surfaces of the nanocomposites showed that the F-MWNTs in the nylon-6 matrix were well dispersed as compared to those of the P-MWNTs. Both nanocomposites could be electrospun into nanofibers in which the MWNTs were embedded and oriented along the nanofiber axis, as confirmed by transmission electron microscopy. The specific strength and modulus of the MWNTs-reinforced nanofibers increased as compared to those of the neat nylon-6 nanofibers. The crystal structure of the nylon-6 in the MWNT/nylon-6 nanofibers was mostly γ-phase, although that of the MWNT/nylon-6 films, which were prepared by hot-pressing the pellets between two aluminum plates and then quenching them in icy water, was mostly α-phase, indicating that the shear force during electrospinning might favor the γ-phase, similarly to the conventional fiber spinning. PMID:20596470

  7. In situ Polymerization of Multi-Walled Carbon Nanotube/Nylon-6 Nanocomposites and Their Electrospun Nanofibers

    NASA Astrophysics Data System (ADS)

    Saeed, Khalid; Park, Soo-Young; Haider, Sajjad; Baek, Jong-Beom

    2009-01-01

    Multiwalled carbon nanotube/nylon-6 nanocomposites (MWNT/nylon-6) were prepared by in situ polymerization, whereby functionalized MWNTs (F-MWNTs) and pristine MWNTs (P-MWNTs) were used as reinforcing materials. The F-MWNTs were functionalized by Friedel-Crafts acylation, which introduced aromatic amine (COC6H4-NH2) groups onto the side wall. Scanning electron microscopy (SEM) images obtained from the fractured surfaces of the nanocomposites showed that the F-MWNTs in the nylon-6 matrix were well dispersed as compared to those of the P-MWNTs. Both nanocomposites could be electrospun into nanofibers in which the MWNTs were embedded and oriented along the nanofiber axis, as confirmed by transmission electron microscopy. The specific strength and modulus of the MWNTs-reinforced nanofibers increased as compared to those of the neat nylon-6 nanofibers. The crystal structure of the nylon-6 in the MWNT/nylon-6 nanofibers was mostly γ-phase, although that of the MWNT/nylon-6 films, which were prepared by hot-pressing the pellets between two aluminum plates and then quenching them in icy water, was mostly α-phase, indicating that the shear force during electrospinning might favor the γ-phase, similarly to the conventional fiber spinning.

  8. In situ Polymerization of Multi-Walled Carbon Nanotube/Nylon-6 Nanocomposites and Their Electrospun Nanofibers.

    PubMed

    Saeed, Khalid; Park, Soo-Young; Haider, Sajjad; Baek, Jong-Beom

    2009-01-01

    Multiwalled carbon nanotube/nylon-6 nanocomposites (MWNT/nylon-6) were prepared by in situ polymerization, whereby functionalized MWNTs (F-MWNTs) and pristine MWNTs (P-MWNTs) were used as reinforcing materials. The F-MWNTs were functionalized by Friedel-Crafts acylation, which introduced aromatic amine (COC(6)H(4)-NH(2)) groups onto the side wall. Scanning electron microscopy (SEM) images obtained from the fractured surfaces of the nanocomposites showed that the F-MWNTs in the nylon-6 matrix were well dispersed as compared to those of the P-MWNTs. Both nanocomposites could be electrospun into nanofibers in which the MWNTs were embedded and oriented along the nanofiber axis, as confirmed by transmission electron microscopy. The specific strength and modulus of the MWNTs-reinforced nanofibers increased as compared to those of the neat nylon-6 nanofibers. The crystal structure of the nylon-6 in the MWNT/nylon-6 nanofibers was mostly gamma-phase, although that of the MWNT/nylon-6 films, which were prepared by hot-pressing the pellets between two aluminum plates and then quenching them in icy water, was mostly alpha-phase, indicating that the shear force during electrospinning might favor the gamma-phase, similarly to the conventional fiber spinning.

  9. 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.

  10. 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.

  11. Photocatalytic reduction of aqueous mercury(II) using multi-walled carbon nanotubes/Pd-ZnO nanocomposite

    SciTech Connect

    Mohamed, R.M.; Abdel Salam, Mohamed

    2014-02-01

    Highlights: • MWCNT/Pd-ZnO were used for photocatalytic reduction of Hg{sup 2+}. • Photocatalytic reduction of Hg{sup 2+} was dependent on wt% of MWCNT, reaction time, and weight of catalyst. • Catalyst re-use revealed the present photocatalyst remain effective and active after five, cycles. - Abstract: Pd-ZnO nanocatalyst supported on multi-walled carbon nanotubes was successfully synthesized via a modified sol–gel method, and the prepared photocatalyst was used for the environmental remediation of aqueous Hg(II) via photocatalytic reduction under visible light. The prepared MWCNTs/Pd/ZnO nanocomposite photocatalyst was characterized using X-ray diffraction, Brunauer–Emmett–Teller (BET), transmission electron microscopy, and UV–vis spectra (UV–vis). The results showed that both Pd and ZnO nanoparticles were well dispersed over the MWCNTs, and a uniform nanocomposite was formed. The results also illustrated that Pd doping can eliminate the recombination of electron-hole pairs in the catalyst, and the presence of MWCNTs in ZnO composite can change surface properties to achieve sensitivity to visible light. The results demonstrated that optimum mass ratio of CNT:ZnO:Pd were 0.04:1.0:0.08, which resulted in the exceptional performance of the photocatalyst to reduce about 100% of Hg(II) in a 100 mg L solution within 30 min.

  12. 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.

  13. Ultrasound-promoted direct functionalization of multi-walled carbon nanotubes in water via Diels-Alder "click chemistry".

    PubMed

    Le, Cuong M Q; Cao, Xuan Thang; Lim, Kwon Taek

    2017-11-01

    A facile and environmentally friendly strategy for grafting polymers onto the surface of multi-walled carbon nanotubes (CNTs) was demonstrated by Diels-Alder "click chemistry". Firstly, the copolymers of poly(styrene-alt-maleic anhydride) (PSM) were prepared by the reversible addition-fragmentation chain transfer (RAFT) polymerization and subsequently functionalized with furfuryl amine to introduce anchoring groups. The copolymers were then grafted on CNTs via the Diels-Alder reaction in water through a conventional heating-stirring route and ultrasound-assisted method. The obtained nanocomposite materials were characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. The results indicated that the reaction rate under ultrasound irradiation was accelerated about 12 times than the one under the conventional heating-stirring condition without losing the grafting efficiency. The direct functionalization of CNTs formed a stably dispersed solution in water, promising a green and effective method for industrial process. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Enhanced sorption of mercury from compact fluorescent bulbs and contaminated water streams using functionalized multiwalled carbon nanotubes.

    PubMed

    Gupta, Avinash; Vidyarthi, S R; Sankararamakrishnan, Nalini

    2014-06-15

    Three different functionalized multiwalled carbon nanotubes were prepared, namely, oxidized CNTs (CNT-OX), iodide incorporated MWCNT (CNT-I) and sulfur incorporated MWCNT (CNT-S). The as prepared adsorbents were structurally characterized by various spectral techniques like scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), Brunauer, Emmett, and Teller (BET) surface area analyzer, Fourier transform infra red (FTIR) and Raman spectroscopy. Loading of iodide and sulfur was evident from the EDAX graphs. The adsorption properties of Hg(2+) as a function of pH, contact time and initial metal concentration were characterized by Cold vapor AAS. The adsorption kinetics fitted the Pseudo second order kinetics and equilibrium was reached within 90 min. The experimental data were modeled with Langmuir, Freundlich, Dubinin-Redushkevich and Temkin isotherms and various isotherm parameters were evaluated. It was found that the mercury adsorption capacity for the prepared adsorbents were in the order of CNT-S>CNT-I>CNT-OX>CNT. Studies have been conducted to demonstrate the applicability of the sorbent toward the removal of Hg(0) from broken compact fluorescent light (CFL) bulbs and Hg(II) from contaminated water streams. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Effects of NH3 PECVD treatment time on the performance of multiwall carbon nanotubes for antibody immobilization.

    PubMed

    Hu, Chih-Chung; Chiou, Ai-Huei; Hsu, Chun-Yao

    2016-10-01

    This work presents an amino plasma-enhanced chemical vapour deposition (NH3 PECVD) treatment to modify multiwall carbon nanotubes (MWCNTs) for the immobilization of antibodies (IgG-gold), and the effects of treatment time were studied. A titanium nitride (TiN) buffer layer and a nickel catalyst layer were deposited on silicon substrates for synthesis of MWCNTs using thermal CVD. The MWCNTs were modified by amine (NH2 (-) ) or amino (NH(-) ) functional groups for 1, 3, and 5 min by PECVD, respectively. Mouse IgG-golds were immobilized on the modified MWCNTs using glutaraldehyde (GA) as a crosslinker. The performance of the modified MWCNTs was characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectroscopy (FT-IR), contact angle system (CA), X-ray photoelectron spectroscopy (XPS, ESCA), and UV-visible spectroscopy. Results show that the efficiency of IgG-gold immobilization was increased with the increase of NH3 PECVD treatment time. The NH3 PECVD treatment changed the surface properties of the MWCNTs, tuning them more hydrophilic without affecting their structure. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1343-1351, 2016. © 2015 Wiley Periodicals, Inc.

  16. Solvent-free functionalization of fullerene C60 and pristine multi-walled carbon nanotubes with aromatic amines

    NASA Astrophysics Data System (ADS)

    Ramírez-Calera, Itzel J.; Meza-Laguna, Victor; Gromovoy, Taras Yu.; Chávez-Uribe, Ma. Isabel; Basiuk, Vladimir A.; Basiuk, Elena V.

    2015-02-01

    We employed a direct one-step solvent-free covalent functionalization of solid fullerene C60 and pristine multi-walled carbon nanotubes (MWCNTs) with aromatic amines 1-aminopyrene (AP), 2-aminofluorene (AF) and 1,5-diaminonaphthalene (DAN). The reactions were carried out under moderate vacuum, in a wide temperature range of 180-250 °C, during relatively short time of about 2 h. To confirm successful amine attachment, a large number of analytical techniques were used (depending on the nanomaterial functionalized) such as Fourier transform infrared, Raman, X-ray photoelectron, 13C cross-polarization magic angle spinning NMR spectroscopy, thermogravimetric analysis, laser-desorption ionization time-of-flight mass spectrometry, temperature-programmed desorption with mass spectrometric detection, as well as scanning and transmission electron microscopy. The nucleophilic addition of the aromatic amines to C60 molecule was studied theoretically by using density functional theory (PBE GGA functional with Grimme dispersion correction in conjunction with the DNP basis set). In the case of crystalline C60, the solvent-free technique has a limited applicability due to poor diffusion of vaporous aromatic amines into the bulk. Nevertheless, the approach proposed allows for a facile preparation of aromatic amine-functionalized pristine MWCNTs without contamination with other chemical reagents, detergents and solvents, which is especially important for a vast variety of nanotube applications spanning from nanoelectronics to nanomedicine.

  17. Genotoxicity evaluation of nanosized titanium dioxide, synthetic amorphous silica and multi-walled carbon nanotubes in human lymphocytes.

    PubMed

    Tavares, Ana M; Louro, Henriqueta; Antunes, Susana; Quarré, Stephanie; Simar, Sophie; De Temmerman, Pieter-Jan; Verleysen, Eveline; Mast, Jan; Jensen, Keld A; Norppa, Hannu; Nesslany, Fabrice; Silva, Maria João

    2014-02-01

    Toxicological characterization of manufactured nanomaterials (NMs) is essential for safety assessment, while keeping pace with innovation from their development and application in consumer products. The specific physicochemical properties of NMs, including size and morphology, might influence their toxicity and have impact on human health. The present work aimed to evaluate the genotoxicity of nanosized titanium dioxide (TiO2), synthetic amorphous silica (SAS) and multiwalled carbon nanotubes (MWCNTs), in human lymphocytes. The morphology and size of those NMs were characterized by transmission electron microscopy, while the hydrodynamic particle size-distributions were determined by dynamic light scattering. Using a standardized procedure to ensure the dispersion of the NMs and the cytokinesis-block micronucleus assay (without metabolic activation), we observed significant increases in the frequencies of micronucleated binucleated cells (MNBCs) for some TiO2 NMs and for two MWCNTs, although no clear dose-response relationships could be disclosed. In contrast, all forms of SAS analyzed in this study were unable to induce micronuclei. The present findings increase the weight of evidence towards a genotoxic effect of some forms of TiO2 and some MWCNTs. Regarding safety assessment, the differential genotoxicity observed for closely related NMs highlights the importance of investigating the toxic potential of each NM individually, instead of assuming a common mechanism and equal genotoxic effects for a set of similar NMs. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Multiwall carbon nanotubes/polycaprolactone scaffolds seeded with human dental pulp stem cells for bone tissue regeneration.

    PubMed

    Flores-Cedillo, M L; Alvarado-Estrada, K N; Pozos-Guillén, A J; Murguía-Ibarra, J S; Vidal, M A; Cervantes-Uc, J M; Rosales-Ibáñez, R; Cauich-Rodríguez, J V

    2016-02-01

    Conventional approaches to bone regeneration rarely use multiwall carbon nanotubes (MWCNTs) but instead use polymeric matrices filled with hydroxyapatite, calcium phosphates and bioactive glasses. In this study, we prepared composites of MWCNTs/polycaprolactone (PCL) for bone regeneration as follows: (a) MWCNTs randomly dispersed on PCL, (b) MWCNTs aligned with an electrical field to determine if the orientation favors the growing of human dental pulp stem cells (HDPSCs), and (c) MWCNTs modified with β-glycerol phosphate (BGP) to analyze its osteogenic potential. Raman spectroscopy confirmed the presence of MWCNTs and BGP on PCL, whereas the increase in crystallinity by the addition of MWCNTs to PCL was confirmed by X-ray diffraction and differential scanning calorimetry. A higher elastic modulus (608 ± 4.3 MPa), maximum stress (42 ± 6.1 MPa) and electrical conductivity (1.67 × 10(-7) S/m) were observed in non-aligned MWCNTs compared with the pristine PCL. Cell viability at 14 days was similar in all samples according to the live/dead assay, but the 21 day cell proliferation, measured by MTT was higher in MWCNTs aligned with BGP. Von Kossa and Alizarin red showed larger amounts of mineral deposits on MWCNTs aligned with BGP, indicating that at 21 days, this scaffold promotes osteogenic differentiation of HDPSCs.

  19. 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.

  20. 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.

  1. 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

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

    PubMed

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

    2016-08-01

    A novel magnetic carboxylated multi-walled carbon nanotubes (c-MWCNT-MNPs) was proposed for magnetic solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry to determine phenolic compounds in sesame oil. In this study, c-MWCNT-MNPs were acquired by simply dispersing Fe3O4 magnetic nanoparticles into carboxylated multi-walled carbon nanotubes. The major parameters affecting extraction efficiency were optimized, including the type and volume of desorption solvents, extraction and desorption time, washing solution, and sorbent amount. The limit of quantifications and limit of detections were from 0.03μg/kg to 43.00μg/kg and from 0.01μg/kg to 13.60μg/kg, respectively. The recoveries of phenolic compounds in vegetable oils were in the range of 83.8-125.9% with inter-day and intra-day precisions of less than 13.2%. It was confirmed that this method was simple, rapid and reliable with an excellent potential for routine analysis of phenolic compounds in oil samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Growth of Vertically Aligned Carbon Nanotube Films: Single- versus Multi-walled

    NASA Astrophysics Data System (ADS)

    Gupta, Sanju; Wang, Yunyu

    2005-03-01

    Vertically aligned high density small diameter carbon nanotube films were deposited by microwave CVD technique. The iron catalyst was prepared by E-beam evaporation on thermally grown silicon dioxide n-type Si(100) substrates. Experiments show that by continuous reduction in the thickness of Fe (˜ 3-5), smaller diameter carbon nanotube can be achieved. Scanning electron and high-resolution transmission electron microscopy show that the diameter of carbon nanotubes ranged ˜ 1 - 5 nm and the films are comprised of both the single- and double-wall carbon nanotubes. Visible Raman spectroscopy was used to further verify the diameter of nanotubes. A thick iron film (80 nm) was also used to grow nanotubes for comparison. The results show that the catalyst islands become greater than hundred nanometers with increasing thickness and induce multi-wall and bamboo-like microstructures. While for thinner layer of iron films smaller sizes of catalyst particles/droplets produce hollow concentric tubes without bamboo structure and with less number of walls (single-wall and double-wall carbon nanotubes). The base growth was the most appropriate model to describe the growth mechanism for our films. The electron field emission properties such as field electron emission microscopy (FEEM) in conjunction with the temperature dependence (T-FEEM) were measured to investigate the emission site density and their intensity variation. These findings in terms of the role of adsorption will be briefly discussed.

  4. Development of scalable methods for the utilization of multi-walled carbon nanotubes in polymer and metal matrix composites

    NASA Astrophysics Data System (ADS)

    Vennerberg, Danny Curtis

    Multi-walled carbon nanotubes (MWCNTs) have received considerable attention as reinforcement for composites due to their high tensile strength, stiffness, electrical conductivity and thermal conductivity as well as their low coefficient of thermal expansion. However, despite the availability of huge quantities of low-cost, commercially synthesized nanotubes, the utilization of MWCNTs in engineering composites is extremely limited due to difficulties in achieving uniform dispersion and strong interfacial bonding with the matrix. A proven method of enhancing the nanotube-polymer interface and degree of MWCNT dispersion involves functionalizing the MWCNTs through oxidation with strong acids. While effective at laboratory scales, this technique is not well-suited for large-scale operations due to long processing times, poor yield, safety hazards, and environmental concerns. This work aims to find scalable solutions to several of the challenges associated with the fabrication of MWCNT-reinforced composites. For polymer matrix composite applications, a rapid, dry, and cost-effective method of oxidizing MWCNTs with O3 in a fluidized bed was developed as an alternative to acid oxidation. Oxidized MWCNTs were further functionalized with silane coupling agents using water and supercritical carbon dioxide as solvents in order to endow the MWCNTs with matrix-specific functionalities. The effect of silanization on the cure kinetics, rheological behavior, and thermo-mechanical properties of model epoxy nanocomposites were investigated. Small additions of functionalized MWCNTs were found to increase the glass transition temperature, strength, and toughness of the epoxy. In order to achieve composite properties approaching those of individual nanotubes, new approaches are needed to allow for high loadings of MWCNTs. One strategy involves making macroscopic mats of nanotubes called buckypaper (BP) and subsequently infiltrating the mats with resin in processes familiar to

  5. n-Type field-effect transistors made of an individual nitrogen-doped multiwalled carbon nanotube.

    PubMed

    Xiao, Kai; Liu, Yunqi; Hu, Ping'an; Yu, Gui; Sun, Yanming; Zhu, Daoben

    2005-06-22

    We report on the fabrication and characterization of field-effect transistor based on an individual multiwalled nitrogen-doped carbon nanotube. Our measurements show that the N-doped carbon nanotubes have n-type properties. The contact properties of the tube and Pt electrodes are also studied in detail. Temperature dependence of two-terminal transport experiments suggests that transport is dominated by thermionic emission and tunneling through a 0.2 eV Schottky contact barrier.

  6. Dispersion and separation of nanostructured carbon in organic solvents

    NASA Technical Reports Server (NTRS)

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

  7. Polyaniline/multiwall carbon nanotubes/starch nanocomposite material and hemoglobin modified carbon paste electrode for hydrogen peroxide and glucose biosensing.

    PubMed

    Gautam, Vineeta; Singh, Karan Pratap; Yadav, Vijay Laxmi

    2018-01-30

    This paper describes the application of novel nanocomposite material polyaniline/multiwall carbon nanotubes/starch (designated as PCS) as a good electrode material for electrochemical sensing. The developed ternary composite system has manifold interactions and synergistic improved properties - high surface area, good electro-activity, conductivity, stable dispersion, biocompatible, hydrophilic and hydrophobic regions, multifunctional, and nanoturmeric shape morphology. Hydrogen peroxide biosensor was fabricated as a model system using PCS and hemoglobin (HB) modified carbon paste electrode. PCS and HB compatible and effectively communicate with each other, facilitate the charge transfer (potassium ferricyanide used as electroactive marker). Thus, PCS and HB (in combination) is a good electrode material for sensitive and selective detection of peroxide. The developed biosensor showed a linear range (0.1 mM-5 mM, R2 = 0.9975), limit of detection (0.032 mM), sensitivity (76.43 μA/mM cm2) and long-term storage and stability. This material could be used a platform to develop some other sensors by using other redox enzymes. As a model, we incorporate glucose oxidase to detect Glucose. Thus, the favorable properties indicate that the proposed material system suitable for low-cost sensor strips. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Facile synthesis of β-lactoglobulin-functionalized multi-wall carbon nanotubes and gold nanoparticles on glassy carbon electrode for electrochemical sensing.

    PubMed

    Du, Xin; Miao, Zhiying; Zhang, Di; Fang, Yuxin; Ma, Min; Chen, Qiang

    2014-12-15

    A facile approach was developed for the preparation of nanocomposite based on β-lactoglobulin (BLG)-functionalized multi-wall carbon nanotubes (MWCNTs) and gold nanoparticles (GNPs) for the first time. Owing to the amphipathic nature, BLG can be adopted onto the surface of MWCNTs to form BLG-MWCNTs with uniform dispersion in water. Taking advantage of sulfhydryl groups on BLG-MWCNTs, GNPs were decorated on the BLG-MWCNTs-modified glassy carbon electrode (GCE) by electrodeposition. The nanocomposite was characterized by transmission electron microscopy, scanning electron microscopy and X-ray spectroscopy analysis. Cyclic voltammetry and chronoamperometric method were used to evaluate the electrocatalytic ability of the nanocomposite. Furthermore, a glucose biosensor was developed based on the immobilization of glucose oxidase with cross-linking in the matrix of bovine serum albumin (BSA) on the nanocomposite modified GCE. The resulting biosensor exhibited high sensitivity (3.98 μA mM(-1)), wider linear range (0.025-5.5 mM), low detection limit (1.1 μM at the signal-to-noise ratio of 3) and fast response time (within 7s) for glucose detection. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. An electrochemical sensor for rizatriptan benzoate determination using Fe3O4 nanoparticle/multiwall carbon nanotube-modified glassy carbon electrode in real samples.

    PubMed

    Madrakian, Tayyebeh; Maleki, Somayeh; Heidari, Mozhgan; Afkhami, Abbas

    2016-06-01

    In this paper a sensitive and selective electrochemical sensor for determination of rizatriptan benzoate (RZB) was proposed. A glassy carbon electrode was modified with nanocomposite of multiwalled carbon nanotubes (MWCNTs) and Fe3O4 nanoparticles (Fe3O4/MWCNTs/GCE). The results obtained clearly show that the combination of MWCNTs and Fe3O4 nanoparticles definitely improves the sensitivity of modified electrode to RZB determination. The morphology and electroanalytical performance of the fabricated sensor were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), square wave voltammetry (SWV) and cyclic voltammetry (CV). Also, the effect of experimental and instrumental parameters on the sensor response was evaluated. The square wave voltammetric response of the electrode to RZB was linear in the range 0.5-100.0 μmol L(-1) with a detection limit of 0.09 μmol L(-1) under the optimum conditions. The investigated method showed good stability, reproducibility and repeatability. The proposed sensor was successfully applied for real life samples of blood serum and RZB determination in pharmaceutical. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Ultraviolet pulsed laser irradiation of multi-walled carbon nanotubes in nitrogen atmosphere

    SciTech Connect

    Pérez del Pino, Ángel, E-mail: aperez@icmab.es; Cabana, Laura; Tobias, Gerard

    2014-03-07

    Laser irradiation of randomly oriented multi-walled carbon nanotube (MWCNT) networks has been carried out using a pulsed Nd:YAG UV laser in nitrogen gas environment. The evolution of the MWCNT morphology and structure as a function of laser fluence and number of accumulated laser pulses has been studied using electron microscopies and Raman spectroscopy. The observed changes are discussed and correlated with thermal simulations. The obtained results indicate that laser irradiation induces very fast, high temperature thermal cycles in MWCNTs which produce the formation of different nanocarbon forms, such as nanodiamonds. Premelting processes have been observed in localized sites by irradiationmore » at low number of laser pulses and low fluence values. The accumulation of laser pulses and the increase in the fluence cause the full melting and amorphization of MWCNTs. The observed structural changes differ from that of conventional high temperature annealing treatments of MWCNTs.« less

  11. Laser heating effect on Raman spectra of styrene-butadiene rubber/multiwalled carbon nanotube nanocomposites

    NASA Astrophysics Data System (ADS)

    Yan, Xinlei; Kitahama, Yasutaka; Sato, Harumi; Suzuki, Toshiaki; Han, Xiaoxia; Itoh, Tamitake; Bokobza, Liliane; Ozaki, Yukihiro

    2012-01-01

    The laser heating effect on MWCNTs in styrene-butadiene rubber/multiwalled carbon nanotube (SBR/MWCNT) composites were studied by Raman spectra. The intensity ratio of the D band to G band (ID/IG) of SBR/MWCNT composites largely decreased with temperature. This indicates the self-rearranging behavior of MWCNTs in the SBR/MWCNTs system during temperature increase. In addition, the temperature-dependent downward shift of the G band of SBR/MWCNT composites was smaller than that of MWCNTs samples. The self-rearrangement of MWCNTs in SBR/MWCNT composites and a mechanical compression were explained as two possible reasons for the different behavior of the G band shift.

  12. Ultraviolet pulsed laser irradiation of multi-walled carbon nanotubes in nitrogen atmosphere

    SciTech Connect

    Pérez del Pino, Ángel Cabana, Laura; Tobias, Gerard; György, Enikö; Ballesteros, Belén

    2014-03-07

    Laser irradiation of randomly oriented multi-walled carbon nanotube (MWCNT) networks has been carried out using a pulsed Nd:YAG UV laser in nitrogen gas environment. The evolution of the MWCNT morphology and structure as a function of laser fluence and number of accumulated laser pulses has been studied using electron microscopies and Raman spectroscopy. The observed changes are discussed and correlated with thermal simulations. The obtained results indicate that laser irradiation induces very fast, high temperature thermal cycles in MWCNTs which produce the formation of different nanocarbon forms, such as nanodiamonds. Premelting processes have been observed in localized sites by irradiation at low number of laser pulses and low fluence values. The accumulation of laser pulses and the increase in the fluence cause the full melting and amorphization of MWCNTs. The observed structural changes differ from that of conventional high temperature annealing treatments of MWCNTs.

  13. Planarized arrays of aligned, untangled multiwall carbon nanotubes with Ohmic back contacts

    SciTech Connect

    Rochford, C.; Limmer, S. J.; Howell, S. W.; Beechem, T. E.; Siegal, M. P.

    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 WO3 layer. The WO3 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 grown 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.

  14. MHDA-Functionalized Multiwall Carbon Nanotubes for detecting non-aromatic VOCs

    PubMed Central

    Thamri, Atef; Baccar, Hamdi; Struzzi, Claudia; Bittencourt, Carla; Abdelghani, Adnane; Llobet, Eduard

    2016-01-01

    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. PMID:27721503

  15. 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

  16. Photoactuators on the base of polymeric elastomers and multiwall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Czaníková, Kl.; Krupa, I.; Ilcíková, M.; Mosnáček, J.; Kasák, P.; Mičušík, M.; Chorvát, D., Jr.; Omastová, M.

    2011-10-01

    Photomechanical actuation is preferred to electromechanical transduction because of some advantages including wireless connection, a producing low noise, fast response etc. However, only few materials actually exhibit photoactuation. Recently, nanotube-enriched elastomeric polymers have shown photo-actuating properties; the best results were reported for liquid crystals elastomers. In the present paper we discuss photo-actuating behavior of new photoactuating materials based on the commercial elastomer such as ethylene-vinylacetate copolymer (EVA) filled with multiwalled carbon nanotubes (MWCNT) modified with novel, specific surfactant consisting of pyrenenyl and cholesteryl groups. Orientation of MWCNT within the matrix was created by shear forces employing a special punch and die system. Photo-actuation was characterized using AFM.

  17. Growth of small diameter multi-walled carbon nanotubes by arc discharge process

    NASA Astrophysics Data System (ADS)

    T. Chaudhary, K.; J., Ali; P. Yupapin, P.

    2014-03-01

    Multi-walled carbon nanotubes (MWCNTs) are grown by arc discharge method in a controlled methane environment. The arc discharge is produced between two graphite electrodes at the ambient pressures of 100 torr, 300 torr, and 500 torr. Arc plasma parameters such as temperature and density are estimated to investigate the influences of the ambient pressure and the contributions of the ambient pressure to the growth and the structure of the nanotubes. The plasma temperature and density are observed to increase with the increase in the methane ambient pressure. The samples of MWCNT synthesized at different ambient pressures are analyzed using transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. An increase in the growth of MWCNT and a decrease in the inner tube diameter are observed with the increase in the methane ambient pressure.

  18. Effect of Multiwall Carbon Nanotube Reinforcement on Coaxially Extruded Cellular Vascular Conduits

    PubMed Central

    Zhang, Yahui; Yu, Yin; Dolati, Farzaneh; Ozbolat, Ibrahim T

    2014-01-01

    Due to its abundant source, good biocompatibility, low price and mild crosslinking process, alginate is an ideal selection for tissue engineering applications. In this work, alginate vascular conduits were fabricated through a coaxial extrusion-based system. However, due to the inherent weak mechanical properties of alginate, the vascular conduits are not capable of biomimicking natural vascular system. In this paper, multiwall carbon nanotubes (MWCNT) were used to reinforce vascular conduits. Mechanical, dehydration, swelling and degradation tests were performed to understand influences of MWCNT reinforcement. The unique mechanical properties together with perfusion and diffusional capability are two important factors to mimic the nature. Thus, perfusion experiments were also conducted to explore the MWCNT reinforcement effect. In addition, cell viability and tissue histology were conducted to evaluate the biological performance of conduits both in short and long term for MWCNT reinforcement. PMID:24863208

  19. 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

  20. 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.

  1. Immobilization of Aspergillus niger cellulase on multiwall carbon nanotubes for cellulose hydrolysis.

    PubMed

    Ahmad, Razi; Khare, Sunil Kumar

    2018-03-01

    In present study, Aspergillus niger cellulase was immobilized onto functionalized multiwalled carbon nanotubes (MWCNTs) via carbodiimide coupling. MWCNTs offer unique advantages including enhanced electronics properties, a large edge to basal plane ratio, rapid electrode kinetics and it's possess higher tensile strength properties due to their structural arrangements. The immobilization was confirmed by FTIR (Fourier transform infrared spectroscopy) and SEM (scanning electron microscope). The bionanoconjugates prepared under optimized condition retained 85% activity with improved pH and thermal stability. The t 1/2 of immobilized cellulase at 70 °C was four fold higher than free enzyme. The Km value indicates that affinity of bionanoconjugates towards substrate has increased by two times. The preparation could be reused ten times without much loss in enzyme activity. The enhanced catalytic efficiency, stability and reusability makes it useful for efficient cellulose hydrolysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Dynamic Behavior of Nanocomposites Reinforced with Multi-Walled Carbon Nanotubes (MWCNTs)

    PubMed Central

    Her, Shiuh-Chuan; Lai, Chun-Yu

    2013-01-01

    The influence of multi-walled carbon nanotubes (MWCNT) on the structural dynamic behavior of MWCNT/epoxy nanocomposites was investigated. Two different types of MWCNTs, pristine MWCNT and functionalized MWCNT, were used in this study. Carboxylic acid-functionalized MWCNTs (MWCNT-COOH) were obtained by oxidation pristine MWCNTs via sonication in sulfuric-nitric acid and characterized by Fourier transform infrared spectroscopy (FTIR). Dynamic behaviors of the MWCNT reinforced nanocomposite including the natural frequency and damping ratio were determined using free vibration test. Experimental results showed that the damping ratio of the nanocomposite decreases with the increase of the MWCNT addition, while the natural frequency is increasing with the increase of the MWCNT addition. Functionalized MWCNTs improved the interfacial bonding between the nanotubes and epoxy resin resulting in the reduction of the interfacial energy dissipation ability and enhancement of the stiffness. PMID:28809273

  3. Rippling and a phase-transforming mesoscopic model for multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Arroyo, M.; Arias, I.

    We propose to model thick multiwalled carbon nanotubes as beams with non-convex curvature energy. Such models develop stressed phase mixtures composed of smoothly bent sections and rippled sections. This model is motivated by experimental observations and large-scale atomistic-based simulations. The model is analyzed, validated against large-scale simulations, and exercised in examples of interest. It is shown that modelling MWCNTs as linear elastic beams can result in poor approximations that overestimate the elastic restoring force considerably, particularly for thick tubes. In contrast, the proposed model produces very accurate predictions both of the restoring force and of the phase pattern. The size effect in the bending response of MWCNTs is also discussed.

  4. 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.

  5. 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.

  6. 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.

  7. Phytotoxicity of multi-walled carbon nanotubes assessed by selected plant species in the seedling stage

    NASA Astrophysics Data System (ADS)

    Begum, Parvin; Ikhtiari, Refi; Fugetsu, Bunshi; Matsuoka, Makoto; Akasaka, Tsukasa; Watari, Fumio

    2012-12-01

    Abundant experimental data have shown that multi-walled carbon nanotubes (MWNTs) are toxic to plants, but the potential impacts of exposure remain unclear. The objective of the present study was to evaluate possible phytotoxicity of MWNTs at 0, 20, 200, 1000, and 2000 mg/L with red spinach, lettuce, rice, cucumber, chili, lady's finger, and soybean based on root and shoot growth, cell death, and electrolyte leakage at the seedling stage. After 15 days of hydroponic culture, the root and shoot lengths of red spinach, lettuce, and cucumber were significantly reduced following exposure to 1000 mg/L and 2000 mg/L MWNTs. Similar toxic effects occurred regarding cell death and electrolyte leakage. Red spinach and lettuce were most sensitive to MWNTs, followed by rice and cucumber. Very little or no toxic effects were observed for chili, lady's finger, and soybean.

  8. Improved field emission from indium decorated multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sreekanth, M.; Ghosh, S.; Biswas, P.; Kumar, S.; Srivastava, P.

    2016-10-01

    Multi-walled carbon nanotube (MWCNT) films were grown using thermal chemical vapor deposition (T-CVD) process and were decorated with indium metal particles by thermal evaporation technique. The In metal particles are found to get oxidized. The In decorated films show 250% enhancement in the FE current density, lower turn-on and threshold fields, and better temporal stability as compared to their undecorated counterpart. This improvement in field emission properties is primarily attributed to increased density of states near the Fermi level. The presence of O 2p states along with a small contribution from In 5s states results in the enhancement of density of states in the vicinity of the Fermi level.

  9. Kinetics, equilibrium and thermodynamics of the sorption of tetrabromobisphenol A on multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Fasfous, Ismail I.; Radwan, Enas S.; Dawoud, Jamal N.

    2010-09-01

    Tetrabromobisphenol A (TBBPA) is widely used as a flame retardant and is relatively persistent in the environment. This study reports the sorption kinetics, equilibrium and thermodynamics of TBBPA on multiwalled carbon nanotubes (MWCNTs). The equilibrium sorption capacity has been significantly improved by increasing the initial TBBPA concentration and contact time. In alkaline conditions and at high temperatures, a large reduction of TBBPA uptake was observed. The equilibrium between TBBPA and MWCNTs was achieved in approximately 60 min with removal of 96% of the TBBPA. The sorption kinetics were well described by a pseudo-second-order rate model, while both Langmuir and Freundlich models described the sorption isotherms well at different temperatures. Thermodynamic parameters suggested that the sorption of TBBPA is exothermic and spontaneous at the temperatures studied.

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

    SciTech Connect

    Keramatnejad, K.; Zhou, Y. S.; Gao, Y.; Rabiee Golgir, H.; Wang, M.; Lu, Y. F.; Jiang, L.; Silvain, J.-F.

    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 play a crucial role in reducing contact resistance at the MWCNT-Cu interfaces, removing impurities in MWCNTs, and densifying MWCNT films.

  11. 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

  12. Multiwalled carbon nanotubes grown in hydrogen atmosphere: An x-ray diffraction study

    SciTech Connect

    Maniwa, Yutaka; Fujiwara, Ryuji; Kira, Hiroshi

    2001-08-15

    X-ray diffraction study of multiwalled carbon nanotube (MWNT) grown by arc discharge in hydrogen atmosphere is presented. It is found that the thermal-expansion coefficient along the radial direction of MWNT is widely distributed in a range from 1.6 x 10{sup -5} K{sup -1} to 2.6 x 10{sup -5} K{sup -1}, indicating the existence of both of Russian doll MWNT and highly defective MWNT. Russian doll MWNT is suggested to have the outer diameter less than {approx}100 Aa. Thicker MWNT's are typically highly defective, and may have the jelly roll (scroll) or defective polygonal structure consisting of flat graphite domains.

  13. Catalytic ozonation of dimethyl phthalate using Fe3O4/multi-wall carbon nanotubes.

    PubMed

    Bai, Zhiyong; Yang, Qi; Wang, Jianlong

    2017-08-01

    In this paper, Fe 3 O 4 /multi-wall carbon nanotubes composites were prepared, characterized and used as a catalyst for enhancing the ozonation of dimethyl phthalate (DMP) in aqueous solution. The experimental results showed that DMP degradation and mineralization increased by 26% and 20%, respectively, in catalytic ozonation compared with single ozonation, and more H 2 O 2 and organic acids were produced during catalytic ozonation process than single ozonation. The effect of pH, ozone concentration and catalyst dosage on DMP degradation was determined. The addition of tert-butanol and phosphates showed a negative effect on DMP degradation, suggesting that the acidic sites on the catalyst is favorable to ozone decomposition to produce hydroxyl radicals. The possible mechanism for catalytic ozonation of DMP was tentatively proposed. The adsorption of ozone and organics onto the surface of catalyst could improve the DMP degradation.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Photoreactivity of hydroxylated multi-walled carbon nanotubes and its effects on the photodegradation of atenolol in water.

    PubMed

    Zhang, Ya; Zhou, Lei; Zeng, Chao; Wang, Qi; Wang, Zunyao; Gao, Shixiang; Ji, Yuefei; Yang, Xi

    2013-11-01

    In spite of the increasing concerns about the fate of pharmaceuticals and personal care products (PPCPs) and the nanomaterial pollution in aquatic ecosystem, the effects of carbon nanotubes on the photochemical transformation of PPCPs are less considered. In this study, the photochemical production of reactive oxygen species (ROS) were examined in colloidal dispersions of hydroxylated multi-walled carbon nanotubes (MWNT-OH) under simulated solar irradiation using a Xenon lamp. Two kinds of ROS, (1)O2 and OH, were confirmed by their molecular probes, furfuryl alcohol (FFA) and p-chlorobenzoic acid (PCBA). The steady-state concentrations of (1)O2 and OH were calculated as 1.30×10(-14) M and 5.02×10(-16) M, respectively. The effects of MWNT-OH on photodegradation of atenolol (ATL) were investigated in the presence of natural water components, i.e., dissolved organic matters (DOMs), nitrate (NO3(-)) and ferric ions (Fe(3+)). Photoproducts of atenolol were identified by solid phase extraction-liquid chromatography-mass spectrometry (SPE-LC-MS) analysis techniques. Three potential photochemical pathways of atenolol, including the hydroxylation on aromatic ring, the loss of amide group and the cleavage of ether oxygen bond as well as di-polymerization of reaction intermediates were tentatively proposed. Using the radical quenching method, reaction with OH was determined as the major photolysis pathway of atenolol in irradiated MWNT-OH suspensions. These findings of the production of ROS and their effects on the photodegradation of organic contaminants provided useful information for assessing environmental risk of MWNT-OH. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Modeling the transport of sodium dodecyl benzene sulfonate in riverine sediment in the presence of multi-walled carbon nanotubes.

    PubMed

    Song, Biao; Xu, Piao; Zeng, Guangming; Gong, Jilai; Wang, Xiaoxiao; Yan, Jin; Wang, Shengfan; Zhang, Peng; Cao, Weicheng; Ye, Shujing

    2018-02-01

    The environmental risks of carbon nanotubes have received considerable attention. In this work, the effects of multi-walled carbon nanotubes (MWCNTs) on the adsorption of sodium dodecyl benzene sulfonate (SDBS) by riverine sediment and the transport of SDBS in sediment were studied. MWCNTs could significantly increase the adsorption capacity of the sediment for SDBS, thus affecting the transport of SDBS in sediment. Maximum adsorption capacity of the sediment for SDBS increases from 2.29 to 2.99 mg/g with the increasing content of MWCNTs from 0% to 1.5%. Breakthrough curves (BTCs) of SDBS obtained from the column experiments were described by the convection-dispersion equation, Thomas model, and Yan model. The estimated retardation factor R increases with the incorporation of MWCNTs, either in water or sediment. Additionally, the value of R is well correlated to the content of MWCNTs in sediment. Compared with Thomas model, Yan model is more suitable for fitting the BTCs with all the values of R2 ≥ 0.951, but it tends to overestimate the maximum adsorption capacity when the content of MWCNTs in sediment is relatively higher. The results of SDBS retention in sediment indicate that MWCNTs can increase the accumulation of SDBS in the top sediment layer, while they can impede the transport of SDBS into deeper sediment layer when incorporated into the sediment. These effects should be taken into consideration for risk assessment of CNTs in the aquatic environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Biosensor based on multi-walled carbon nanotubes paste electrode modified with laccase for pirimicarb pesticide quantification.

    PubMed

    Oliveira, Thiago M B F; Fátima Barroso, M; Morais, Simone; de Lima-Neto, Pedro; Correia, Adriana N; Oliveira, Maria B P P; Delerue-Matos, Cristina

    2013-03-15

    This study focused on the development of a sensitive enzymatic biosensor for the determination of pirimicarb pesticide based on the immobilization of laccase on composite carbon paste electrodes. Multi-walled carbon nanotubes (MWCNTs) paste electrode modified by dispersion of laccase (3%, w/w) within the optimum composite matrix (60:40%, w/w, MWCNTs and paraffin binder) showed the best performance, with excellent electron transfer kinetic and catalytic effects related to the redox process of the substrate 4-aminophenol. No metal or anti-interference membrane was added. Based on the inhibition of laccase activity, pirimicarb can be determined in the range 9.90 × 10(-7) to 1.15 × 10(-5) mol L(-1) using 4-aminophenol as substrate at the optimum pH of 5.0, with acceptable repeatability and reproducibility (relative standard deviations lower than 5%). The limit of detection obtained was 1.8 × 10(-7) mol L(-1) (0.04 mg kg(-1) on a fresh weight vegetable basis). The high activity and catalytic properties of the laccase-based biosensor are retained during ca. one month. The optimized electroanalytical protocol coupled to the QuEChERS methodology were applied to tomato and lettuce samples spiked at three levels; recoveries ranging from 91.0 ± 0.1% to 101.0 ± 0.3% were attained. No significant effects in the pirimicarb electroanalysis were observed by the presence of pro-vitamin A, vitamins B1 and C, and glucose in the vegetable extracts. The proposed biosensor-based pesticide residue methodology fulfills all requisites to be used in implementation of food safety programs. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. 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.

  5. 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.

  6. 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

    2015-05-15

    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

  7. Preparation of Surface Adsorbed and Impregnated Multi-walled Carbon Nanotube/Nylon-6 Nanofiber Composites and Investigation of their Gas Sensing Ability

    PubMed Central

    Lala, Neeta L.; Thavasi, Velmurugan; Ramakrishna, Seeram

    2009-01-01

    We have prepared electrospun Nylon-6 nanofibers via electrospinning, and adsorbed multi-walled carbon nanotubes (MWCNTs) onto the surface of Nylon-6 fibers using Triton® X-100 to form a MWCNTs/Nylon-6 nanofiber composite. The dispersed MWCNTs have been found to be stable in hexafluoroisopropanol for several months without precipitation. A MWCNTs/Nylon-6 nanofiber composite based chemical sensor has demonstrated its responsiveness towards a wide range of solvent vapours at room temperature and only mg quantities of MWCNTs were expended. The large surface area and porous nature of the electrospun Nylon-6/MWCNT nanofibers facilitates greater analyte permeability. The experimental analysis has indicated that the dipole moment, functional group and vapour pressure of the analytes determine the magnitude of the responsiveness. PMID:22389589

  8. Optical limiting effect and ultrafast saturable absorption in a solid PMMA composite containing porphyrin-covalently functionalized multi-walled carbon nanotubes.

    PubMed

    Zhang, Xiao-Liang; Liu, Zhi-Bo; Zhao, Xin; Yan, Xiao-Qing; Li, Xiao-Chun; Tian, Jian-Guo

    2013-10-21

    A versatile solid Poly-methyl-methacrylate (PMMA) composite containing porphyrin-covalently functionalized multi-walled carbon nanotubes (MWNTs-TPP) was prepared through free radical polymerization without additional dispersion stabilizer. Using nanosecond, femtosecond pulse Z-scan and degenerate femtosecond pump-probe techniques, we studied the optical limiting effect, ultrafast saturable absorption and transient differential transmission of the composite. Results show that the solid composite exhibits weaker optical limiting effects than that of the suspension at 532 nm under nanosecond pulse, due to the absence of nonlinear scattering mechanism. The composite also shows ultrafast saturable absorption with a relaxation time about 190 fs at 800 nm under femtosecond pulse due to band-filling effect, comparably to the suspension. The versatile solid composite can be the candidate for uses in applications of ultrafast optical switching and mode-locking element or optical limiter for nanosecond pulse.

  9. 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.

  10. Preparation of chitosan/amino multiwalled carbon nanotubes nanocomposite beads for bilirubin adsorption in hemoperfusion.

    PubMed

    Zong, Wenhui; Chen, Jian; Han, Wenyan; Chen, Jie; Wang, Yue; Wang, Weichao; Cheng, Guanghui; Ou, Lailiang; Yu, Yaoting

    2018-01-01

    Chitosan-carbon nanotube composite beads combines the advantages of chitosan in forming a stable biocompatible framework and carbon nanotube that provide nanometer effects (high strength and high specific surface area etc.). In this study, chitosan/amino multiwalled carbon nanotubes (CS/AMWCNT) composite beads was prepared by phase-inversion method, in which CS and AMWCNT was crosslinked by ethylene glycol diglycidyl ether (EGDE). The CS/AMWCNT nanocomposite beads produced has been characterized by BET, SEM, TGA, and Raman spectroscopy which exhibited enhanced thermal stability due to the incorporation of AMWCNT. Mechanical test results showed that mechanical strength of the CS/AMWCNT composite beads was significantly enhanced when comparing to unmodified chitosan beads, the breakage percentage decreased from 34.1% to 0.67%. The adsorption capacity for bilirubin was measured in PBS and BSA solutions, and the CS/AMWCNT composite beads with 5 wt% AMWCNT showed much higher adsorption capacity (12.7 mg/g in PBS and 7.6 mg/g in BSA) to bilirubin than chitosan beads (8.5 mg/g in PBS and 4.2 mg/g in BSA). Our nanocomposite beads with excellent hemocompatibility has a high potential application in blood purification as an efficient adsorbent for bilirubin. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 96-103, 2018. © 2016 Wiley Periodicals, Inc.

  11. Purification and sidewall functionalization of multiwalled carbon nanotubes and resulting bioactivity in two macrophage models.

    PubMed

    Hamilton, Raymond F; Xiang, Chengcheng; Li, Ming; Ka, Ibrahima; Yang, Feng; Ma, Dongling; Porter, Dale W; Wu, Nianqiang; Holian, Andrij

    2013-03-01

    This study examined the consequences of surface carboxylation of multiwalled carbon nanotubes (MWCNT) on bioactivity. Since commercial raw MWCNT contain impurities that may affect their bioactivity, HCl refluxing was exploited to purify raw "as-received" MWCNT by removing the amorphous carbon layer on the MWCNT surface and reducing the metal impurities (e.g. Ni). The removal of amorphous carbon layer was confirmed by Raman spectroscopy and thermogravimetric analysis. Furthermore, the HCl-purified MWCNT provided more available reaction sites, leading to enhanced sidewall functionalization. The sidewall of HCl-purified MWCNT was further functionalized with the -COOH moiety by HNO(3) oxidation. This process resulted in four distinct MWCNT: raw, purified, -COOH-terminated raw MWCNT, and -COOH-terminated purified MWCNT. Freshly isolated alveolar macrophages from C57Bl/6 mice were exposed to these nanomaterials to determine the effects of the surface chemistry on the bioactivity in terms of cell viability and inflammasome activation. Inflammasome activation was confirmed using inhibitors of cathepsin B and Caspase-1. Purification reduced the cell toxicity and inflammasome activation slightly compared to raw MWCNT. In contrast, functionalization of MWCNT with the -COOH group dramatically reduced the cytotoxicity and inflammasome activation. Similar results were seen using THP-1 cells supporting their potential use for high-throughput screening. This study demonstrated that the toxicity and bioactivity of MWCNT were diminished by removal of the Ni contamination and/or addition of -COOH groups to the sidewalls.

  12. Organic MEMS devices and MWCNT (multi-wall carbon nanotube) interconnects

    NASA Astrophysics Data System (ADS)

    Lempkowski, Robert B.; Qian, Zhengfang

    2010-04-01

    RF system front ends need to be mounted on a circuit board and interconnected to other devices such as antennas and surrounding circuitry functions. Providing suitable RF performing interconnects between or within devices on multi-layer construction has been done typically with doped semiconductors, copper, and occasionally other conductors. This paper discusses the use of organic printed circuit board MEMS switches and varactors, and the use of multi-wall carbon nanotubes as transmission lines and antennas. Carbon nanotube active transistors use single wall carbon nanotubes (SWCNT) with efforts to improve percentages of semiconducting structures. Interconnects are needed not only to connect CNT devices to each other, but to larger structures in order to be able to use subsystems that integrate CNT devices, large scale multifunction ICs, and RF devices used in RF front ends, including antennas. This paper addresses the use of organic substrates as the media for integration of MEMS, interconnects to devices on the substrate, and planar antennas. These methods will be required until complete assembly of all devices and interconnects can be done with processes at the nano-scale level, which is assumed to still need efficient radiative antenna structures at a larger scale for commonly used consumer wireless products.

  13. Nitrogen-induced catalyst restructuring for epitaxial growth of multiwalled carbon nanotubes.

    PubMed

    Pattinson, Sebastian W; Ranganathan, Vinay; Murakami, Hajime K; Koziol, Krzysztof K K; Windle, Alan H

    2012-09-25

    The ability to simply and economically produce carbon nanotubes (CNTs) with a defined chiral angle is crucial for the exploitation of nanotubes for their electrical properties. We investigate a diverse range of nitrogen sources for their ability to control CNT chiral angle via epitaxial growth from highly ordered catalyst particles. Through the use of in situ mass and infrared spectrometry, we elucidate the mechanism by which these ordered catalyst particles are formed, showing that ammonia is a key intermediate in the process. Subsequently, the direct addition of a small amount of ammonia to an otherwise standard CNT synthesis is shown to be able to form catalyst particles that grow single chiral angle multiwalled carbon nanotubes. Variation in the ammonia concentration clarifies the catalyst restructuring necessary for the epitaxial growth of carbon nanotubes and subsequent chiral angle control. The simple addition of a nitrogen source is an attractive route for chiral angle control; however, the model also suggests further ways to optimize CNT chiral angle distributions as well as to improve CNT and graphene yield and crystallinity. This understanding also explains the action of ammonia in its widely used role in activating catalyst prior to CNT growth. Finally, this work highlights the uses of novel surface geometries that are achievable through multiphase catalysts.

  14. Single step synthesis of graphene nanoribbons by catalyst particle size dependent cutting of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Parashar, Upendra Kumar; Bhandari, Suraj; Srivastava, Rajesh Kumar; Jariwala, Deep; Srivastava, Anchal

    2011-09-01

    Graphene nanoribbons are emerging as an interesting material for the study of low dimensional physics and for the applications in future electronics due to its finite energy band gap. However, its applicability for large scale nanoelectronics may not be effectively realized unless graphene nanoribbons could be produced using a simple, viable, cost-effective and scalable technique. Here, we report the one step facile synthesis of few layered graphene nanoribbons (GNRs) by catalytically unzipping multi-walled carbon nanotubes (MWCNTs) based on the solubility of carbon atoms in transition metals. The process is free from aggressive oxidants (such as KMnO4, KClO4, H2SO4, HNO3, etc.) and utilizes the in situ grown nickel nanoparticles for nanotube unzipping. This is an additional advantage over previously used techniques to synthesize GNRs. To observe the effect of catalyst particle size and reaction temperature on cutting length of the nanotubes, a simulation study has been done based on solubility of carbon atoms in metal nanoparticles.

  15. 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.

  16. Effects of multiwalled carbon nanotubes functionalization on the morphology and mechanical and thermal properties of carbon fiber/vinyl ester composites.

    PubMed

    Liao, Wei-Hao; Tien, Hsi-Wen; Hsiao, Sheng-Tsung; Li, Shin-Ming; Wang, Yu-Sheng; Huang, Yuan-Li; Yang, Shin-Yi; Ma, Chen-Chi M; Wu, Yi-Fang

    2013-05-01

    Multiwalled carbon nanotube (MWCNT)/carbon fiber (CF)/vinyl ester (VE) laminate composites have been fabricated in this study. Pristine MWCNTs were treated with acid solution, which formed numerous oxygen-containing functional groups onto their surface, resulting in COOH-MWCNTs. Thereafter, acrylic functional groups were grafted onto the COOH-MWCNTs to generate acryl-MWCNTs. Three types of MWCNTs (pristine MWCNTs, COOH-MWCNTs, and acryl-MWCNTs) were used to reinforce the CF/VE-based composites. The dispersion of MWCNTs in the VE matrix and the interfacial interaction between MWCNTs and the VE matrix were investigated. Thereafter, the individual reinforcement efficiencies of these MWCNTs are compared. The flexural strength of the MWCNT/CF/VE composite with 1.0 phr acryl-MWCNTs content is 29.8% greater than that of neat CF/VE composites, and the flexural modulus of the MWCNT/CF/VE composite is 9.9% higher than that of neat CF/VE composites. Compared with neat CF/VE composites, 1.0 phr acryl-MWCNT/CF/VE composites exhibit an approximately 19.9 °C increase in glass transition temperature (Tg). The coefficients of thermal expansion significantly decreased from 47.2 ppm/°C of the neat CF/VE composites to 35.6 ppm/°C of the acryl-MWCNTs/CF/VE composites with 1 phr acryl-MWCNT content. This study provides a method for developing acryl-MWCNT/CF/VE composites with good dispersion of MWCNTs in VE matrix and strong interfacial interaction between the MWCNTs and VE matrix for enhancing the stress transfer from VE matrix to CF reinforcement.

  17. Genotoxicity of multi-walled carbon nanotubes at occupationally relevant doses.

    PubMed

    Siegrist, Katelyn J; Reynolds, Steven H; Kashon, Michael L; Lowry, David T; Dong, Chenbo; Hubbs, Ann F; Young, Shih-Houng; Salisbury, Jeffrey L; Porter, Dale W; Benkovic, Stanley A; McCawley, Michael; Keane, Michael J; Mastovich, John T; Bunker, Kristin L; Cena, Lorenzo G; Sparrow, Mark C; Sturgeon, Jacqueline L; Dinu, Cerasela Zoica; Sargent, Linda M

    2014-01-30

    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.

  18. 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

  19. Morphology and dielectric properties of poly vinyl chloride-[multiwalled carbon nanotube-barium titanate] hybrid composite

    NASA Astrophysics Data System (ADS)

    Francis, Elizabeth; Tippabattini, J.; Choi, Eun-Sik; Thomas, Sabu; Kim, Jaehwan

    2017-04-01

    In this paper, poly vinyl chloride (PVC) based nano-hybrid composites of multi-walled carbon nanotube (MWCNT) and barium titanate (BT) are prepared by solution casting technique and their morphology and dielectric characteristics are studied. The presence of barium titanate in hybrid composites is confirmed by X-ray Diffraction. Dielectric and morphological studies of PVC-MWCNT composites and PVC-MWCNT-BT hybrid composites also studied to verify the improvement in dielectric properties of PVC-MWCNT-BT hybrid composite compared to PVC-MWCNT composite. The hybrid composites show improved dielectric properties when BT is incorporated as dielectric filler with multi-walled carbon nanotube in PVC. PVC-MWCNT 1 %-BT 3 % hybrid composite showed the highest dielectric constant and the lowest tan δ value among the composites. This hybrid composite is useful for electromagnetic shielding and supercapacitor applications.

  20. Growth of Multi-Walled Carbon Nanotubes by Injection CVD Using Cyclopentadienyliron Dicarbonyl Dimer and Cyclooctatetraene Iron Tricarbonyl

    NASA Technical Reports Server (NTRS)

    Harris, Jerry D.; Raffaelle, Ryne P.; Gennett, Thomas; Landi, Brian J.; Hepp, Aloysius F.

    2004-01-01

    Preferential oriented multiwalled carbon nanotubes were prepared by the injection chemical vapor deposition (CVD) method using either cyclopentadienyliron dicarbonyl dimer or cycloctatetraene iron tricarbonyl as the iron catalyst source. The catalyst precursors were dissolved in toluene as the carrier solvent for the injections. The concentration of the catalyst was found to influence both the growth of the nanotubes as well as the amount of iron in the deposited material. As deposited the multiwalled carbon nanotubes contained as little as 2.8% iron by weight. The material was deposited onto tantalum foil and fused silica substrates. The nanotubes were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and thermogravimetric analysis. This synthetic route provides a simple and scalable method to deposit MWNTs with a low defect density, low metal content and preferred orientation.

  1. 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

  2. Electrochemical Impedance Studies on Single and Multi-Walled Carbon Nanotubes--Polymer Nanocomposites for Biosensors Development.

    PubMed

    Tertiş, Mihaela; Florea, Anca; Feier, Bogdan; Marian, Iuliu Ovidiu; Silaghi-Dumitrescu, Luminţa; Cristea, Alexandru; Săndulescu, Robert; Cristea, Cecilia

    2015-05-01

    Advances in nanoscience have allowed scientists to incorporate new nanomaterials in biosensing platforms. Carbon nanotubes are nanomaterials that facilitate the charge transfer between the bioelement and the transducer. Electrochemical impedance spectroscopy is a useful technique for the modified surface characterization. In the present approach electrochemical impedance spectroscopy was used to characterize the electrodes modified with different types of carbon nanotubes (single and multi-wall) according to their morphology and electrochemical behavior. By using Nyquist and Bode diagrams it was possible to assign the appropriate circuit considering all possible contributors. The charge transfer resistances as well as the time constants were calculated for all five types of investigated carbon nanotubes.

  3. 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...

  4. 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.

  5. A Novel Activated-Charcoal-Doped Multiwalled Carbon Nanotube Hybrid for Quasi-Solid-State Dye-Sensitized Solar Cell Outperforming Pt Electrode.

    PubMed

    Arbab, Alvira Ayoub; Sun, Kyung Chul; Sahito, Iftikhar Ali; Qadir, Muhammad Bilal; Choi, Yun Seon; Jeong, Sung Hoon

    2016-03-23

    Highly conductive mesoporous carbon structures based on multiwalled carbon nanotubes (MWCNTs) and activated charcoal (AC) were synthesized by an enzymatic dispersion method. The synthesized carbon configuration consists of synchronized structures of highly conductive MWCNT and porous activated charcoal morphology. The proposed carbon structure was used as counter electrode (CE) for quasi-solid-state dye-sensitized solar cells (DSSCs). The AC-doped MWCNT hybrid showed much enhanced electrocatalytic activity (ECA) toward polymer gel electrolyte and revealed a charge transfer resistance (RCT) of 0.60 Ω, demonstrating a fast electron transport mechanism. The exceptional electrocatalytic activity and high conductivity of the AC-doped MWCNT hybrid CE are associated with its synchronized features of high surface area and electronic conductivity, which produces higher interfacial reaction with the quasi-solid electrolyte. Morphological studies confirm the forms of amorphous and conductive 3D carbon structure with high density of CNT colloid. The excessive oxygen surface groups and defect-rich structure can entrap an excessive volume of quasi-solid electrolyte and locate multiple sites for iodide/triiodide catalytic reaction. The resultant D719 DSSC composed of this novel hybrid CE fabricated with polymer gel electrolyte demonstrated an efficiency of 10.05% with a high fill factor (83%), outperforming the Pt electrode. Such facile synthesis of CE together with low cost and sustainability supports the proposed DSSCs' structure to stand out as an efficient next-generation photovoltaic device.

  6. Electrical and dielectric properties of foam injection-molded polypropylene/multiwalled carbon nanotube composites

    SciTech Connect

    Ameli, A.; Nofar, M.; Saniei, M.; Hossieny, N.; Park, C. B.; Pötschke, P.

    2015-05-22

    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 in 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.

  7. Multi-walled carbon nanotubes induce cytotoxicity, genotoxicity and apoptosis in normal human dermal fibroblast cells.

    PubMed

    Patlolla, Anita; Knighten, Brionna; Tchounwou, Paul

    2010-01-01

    Multi-walled carbon nanotubes (MWCNT) have won enormous popularity in nanotechnology. Due to their unusual, one dimensional, hollow nanostructure and unique physicochemical properties they are highly desirable for use within the commercial, environmental and medical sectors. Despite their wide application, little information is known concerning their impact on human health and the environment. While nanotechnology looms large with commercial promise and potential benefit, an equally large issue is the evaluation of potential effects on humans and other biological systems. Our research is focused on cellular response to purified MWCNT in normal human dermal fibroblast cells (NHDF). Three doses (40, 200, 400 microg/mL) of MWCNT and control (tween-80+0.9% saline) were used in this study. Following exposure to MWCNT, cytotoxicity, genotoxicity and apoptosis assays were performed using standard protocols. Our results demonstrated a dose-dependent toxicity with MWCNT. It was found to be toxic and induced massive loss of cell viability through DNA damage and programmed cell-death of all doses compared to control. Our results demonstrate that carbon nanotubes indeed can be very toxic at sufficiently high concentrations and that careful monitoring of toxicity studies is essential for risk assessment.

  8. Electrical and dielectric properties of foam injection-molded polypropylene/multiwalled carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Ameli, A.; Nofar, M.; Saniei, M.; Hossieny, N.; Park, C. B.; Pötschke, P.

    2015-05-01

    A combination of high dielectric permittivity (ɛ') and low dielectric loss (tan δ) is required for charge storage applications. In percolative systems such as conductive polymer composites, however, obtaining high ɛ' 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 in an injection molding process. Electrical conductivity (σ), ɛ' 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 ɛ'=68.3 and tan δ =0.05 (at 1.25 vol.% MWCNT), as opposed to ɛ'=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.

  9. Design and development of multi-walled carbon nanotube-liposome drug delivery platforms.

    PubMed

    Pippa, Natassa; Chronopoulos, Demetrios D; Stellas, Dimitris; Fernández-Pacheco, Rodrigo; Arenal, Raul; Demetzos, Costas; Tagmatarchis, Nikos

    2017-08-07

    The aim of this study is to design and develop delivery platforms made of liposomes and multi-walled carbon nanotubes (MWCNTs). We used different lipids with different main transition temperature (Tm) and differently functionalized MWCNTs with organic addends possessing either positive or negative charge. The phospholipids used for the formulations were 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) (Tm=41°C) and L-α-phosphatidylcholine, hydrogenated Soy (HSPC) (Tm=53°C). By Differential Scanning Calorimetry (DSC), we studied the interaction between the DPPC and HSPC bilayers and MWCNTs. Liposome-MWCNTs delivery platforms prepared according to the protocol used in the literature. We used dynamic and electrophoretic light scattering in order to investigate the physicochemical characteristics of these mixed nanocarriers. The presence of MWCNTs causes alterations of the size of the conventional HSPC and DPPC liposomes. The ζ-potential values of mixed nanocarriers are near zero. This observation indicates the effective incorporation of MWCNTs into the lipid bilayer of liposomes. Fluorescence spectroscopy has been utilized to exact some qualitative information on the internal nanostructure and nanoenvironment of the lipid/carbon nanotube mixed structures. Finally, we conclude that we successfully prepare and completely characterize mixed nanocarriers composed of lipids and MWCNTs, with low toxicity as indicated by in vitro screening. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. On the possibility of electrochemical unzipping of multiwalled carbon nanotubes to produce graphene nanoribbons

    SciTech Connect

    Zehtab Yazdi, Alireza; Roberts, Edward P.L.; Sundararaj, Uttandaraman, E-mail: u.sundararaj@ucalgary.ca

    2016-08-15

    Highlights: • MWCNTs synthesized and electrochemically oxidized to study the formation of GNR • HRTEM, Raman and XPS confirmed no successful unzipping occurred after oxidation • Electrochemical oxidation very unlikely facilitate formation of intercalated MWCNTs - Abstract: Multiwalled carbon nanotubes (MWCNTs) with different geometrical characteristics and chemical doping have been synthesized and electrochemically oxidized to study the possibility of unzipping, and creating graphene nanoribbon (GNR) nanostructures. Modified glassy carbon electrodes of the MWCNTs have been tested in an aqueous electrolyte via anodic scans in a wide range of potentials, followed by keeping at the maximum potential for different times. Themore » microstructural features, structural defects, and functional groups and their elements have been then studied using high resolution transmission electron microscopy (HRTEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. All results have confirmed that no successful unzipping occurs in the MWCNTs after electrochemical oxidation, even for the nitrogen-doped MWCNTs (CN{sub x}-MWCNTs) with reactive nitrogen groups and defective bamboo structures. In contrast to the report by Shinde et al. (J. Am. Chem. Soc. 2011, 133, 4168–4171), it has been concluded that the electrochemical oxidation in aqueous electrolytes is very unlikely to facilitate sufficient incorporation of the intercalated molecules among the walls of the MWCNTs. These molecules are, however, responsible for unzipping of MWCNTs.« less

  11. Electrical and dielectric properties of foam injection-molded polypropylene/multiwalled carbon nanotube composites

    SciTech Connect

    Ameli, A.; Nofar, M.; Saniei, M.

    2015-05-22

    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

  12. 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.

  13. Cytotoxicity evaluation of unfunctionalized multiwall carbon nanotubes-ultrahigh molecular weight polyethylene nanocomposites.

    PubMed

    Mamidi, Narsimha; Leija, Héctor Manuel; Diabb, Jose Manuel; Lopez Romo, Irasema; Hernandez, Diana; Castrejón, Javier Villela; Martinez Romero, Oscar; Barrera, Enrique V; Elias Zúñiga, Alex

    2017-11-01

    The carbon nanotubes were chosen for this study since long, small to medium diameter, and unfunctionalized nanotubes are considered less favorable for nontoxic applications. The intent of the study is to expand the use of CNTs beyond current understood nontoxic means. Multiwall carbon nanotube/ultrahigh molecular weight polyethylene (MWCNT/UHMWPE) nanocomposites were prepared by reinforcing long chain UHMWPE with MWCNTs. These nanocomposites were prepared to study their cytotoxicity assessments with human fibroblast cell lines. Cell adhesion, proliferation, and differentiation were studied with human fibroblast cell lines. In vitro studies revealed good cell viability on the surface of MWCNT/UHMWPE composites even after 72 h. The nanocomposites showed better cell attachment for fibroblasts than pristine UHMWPE. Overall, the results showed that MWCNT/UHMWPE composites displayed good cellular growth and biocompatibility indicating another way CNTs can be nontoxic. These nanocomposites offer nontoxic conditions that can be used in biomedical devices because the long chain UHMWPE is entangled with long MWCNTs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3042-3049, 2017. © 2017 Wiley Periodicals, Inc.

  14. Dependence of the cytotoxicity of multi-walled carbon nanotubes on the culture medium

    NASA Astrophysics Data System (ADS)

    Zhu, Ying; Ran, Tiecheng; Li, Yuguo; Guo, Jinxue; Li, Wenxin

    2006-09-01

    This study examined the influence of multi-walled carbon nanotubes (MWNTs) on the growth of the unicellular protozoan Tetrahymena pyriformis. Contrary to the findings from most other investigations, our experiment indicated that MWNTs stimulated growth of the cells cultured in proteose peptone yeast extract medium (PPY). Atomic force microscopy images and thermogravimetric analysis showed the spontaneous formation of peptone-MWNT conjugates in the medium by noncovalent binding. Uptake of large amounts of the conjugates by Tetrahymena pyriformis was responsible for growth stimulation, evidenced by images with fluorescently labelled peptone. After the PPY medium was replaced by a filtrated pond water medium (FPW), however, inhibition of the growth of cells exposed to MWNTs occurred. Measurements of the level of malondialdehyde and superoxide dismutase activity demonstrated further that MWNTs might be either toxic or nontoxic, depending on the medium used to cultivate Tetrahymena pyriformis. The biological effects of the interaction of MWNTs with some composites in culture media would be helpful for understanding the mechanisms of the toxicity of carbon nanotubes to living systems.

  15. Flexible Infrared Responsive Multi-Walled Carbon Nanotube/Form-Stable Phase Change Material Nanocomposites.

    PubMed

    Wang, Yunming; Mi, Hongyi; Zheng, Qifeng; Ma, Zhenqiang; Gong, Shaoqin

    2015-09-30

    Flexible infrared (IR)-responsive materials, such as polymer nanocomposites, that exhibit high levels of IR responses and short response times are highly desirable for various IR sensing applications. However, the IR-induced photoresponses of carbon nanotube (CNT)/polymer nanocomposites are typically limited to 25%. Herein, we report on a family of unique nanocomposite films consisting of multi-walled carbon nanotubes (MWCNTs) uniformly distributed in a form-stable phase change material (PCM) that exhibited rapid, dramatic, reversible, and cyclic IR-regulated responses in air. The 3 wt % MWCNT/PCM nanocomposite films demonstrated cyclic, IR-regulated on/off electrical conductivity ratios of 11.6 ± 0.6 and 570.0 ± 70.5 times at IR powers of 7.3 and 23.6 mW/mm(2), respectively. The excellent performances exhibited by the MWCNT/PCM nanocomposite films were largely attributed to the IR-regulated cyclic and reversible form-stable phase transitions occurring in the PCM matrix due to MWCNT's excellent photoabsorption and thermal conversion capabilities, which subsequently affected the thickness of the interfacial PCM between adjacent conductive MWCNTs and thus the electron tunneling efficiency between the MWCNTs. Our findings suggest that these unique MWCNT/PCM nanocomposites offer promising new options for high-performance and flexible optoelectronic devices, including thermal imaging, IR sensing, and optical communication.

  16. Intracellular trafficking and therapeutic outcome of multiwalled carbon nanotubes modified with cyclodextrins and polyethylenimine.

    PubMed

    Mazzaglia, Antonino; Scala, Angela; Sortino, Giuseppe; Zagami, Roberto; Zhu, Yanqui; Sciortino, Maria Teresa; Pennisi, Rosamaria; Pizzo, Maria Musarra; Neri, Giulia; Grassi, Giovanni; Piperno, Anna

    2018-03-01

    Functionalized carbon nanotubes (CNTs) have been proposed in the last years as vectors for delivery of biomolecules, proteins and DNA into various cells. In this study, a new multiwalled carbon nanotube β-cyclodextrin platform (MWCNT-CD) modified with branched polyethylenimine (PEI) and doped with Rhodamine (Rhod), MWCNT-CD-PEI-Rhod, was designed and investigated as drug delivery system. The drug binding abilities of MWCNT-CD-PEI-Rhod towards Cidofovir (Cid) and DNA plasmid encoding enhanced green fluorescence protein (pCMS-EGFP) were investigated by complementary spectroscopic techniques. MWCNT-CD-PEI-Rhod showed no significative cytotoxicity and an excellent ability to entrap and delivery Cid. The present study broadens the spectrum of biological evaluation by investigating platform-treatment induced cellular response such as antiviral activity, transfection properties, cellular uptake, internalization mechanisms and cellular localization. The mechanism of cellular uptake was elucidated monitoring the dependence of intracellular red fluorescence from the assembly concentration, time and presence of specific uptake inhibitors. The biological results indicated that MWCNT-CD-PEI-Rhod loaded with Cid and/or pCMS-EGFP crossed the cell membrane via clathrin-dependent pathway and co-localized in lysosomal compartment. However, no green fluorescent protein expression of pCMS-EGFP was detected, whereas the efficient escape of Cid from lysosome and the release close to nuclear region prompted the antiviral activity. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. 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.

  18. 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.

  19. Magnetic MoS2on 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. 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.

  1. Third Sound in Superfluid 4He Films Adsorbed on Packed Multiwall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Menachekanian, Emin

    Third sound is studied for superfluid films of 4He adsorbed on multiwall carbon nanotubes packed into an annular resonator. The third sound is generated with mechanical oscillation of the cell, and detected with carbon bolometers. A filling curve at temperatures near 250 mK shows oscillations in the third sound velocity, with maxima at the completion of the 4th and 5th atomic layers. Sharp changes in the Q factor of the third sound are found at partial layer fillings. Temperature sweeps at a number of fill points show strong broadening effects on the Kosterlitz-Thouless (KT) transition, and rapidly increasing dissipation, in qualitative agreement with the predictions of Machta and Guyer. At the 4th layer completion there is a sudden reduction of the transition temperature TKT , and then a recovery back to linear variation with fill, although the slope is considerably smaller than the KT prediction. These effects might be related to changes in the gas-liquid coexistence regions.

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

    NASA Astrophysics Data System (ADS)

    Tang, Yuechao; Yang, Dong; Qin, Feng; Hu, Jianhua; Wang, Changchun; Xu, Hualong

    2009-08-01

    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 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 with Ni nanoparticles (Ni-MWNTs) for α, β-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).

  3. Amperometric sulfite sensor based on multiwalled carbon nanotubes/ferrocene-branched chitosan composites.

    PubMed

    Zhou, Hong; Yang, Weiwei; Sun, Changqing

    2008-10-19

    A novel amperometric sensor for the determination of sulfite was fabricated based on multiwalled carbon nanotubes (MWCNTs)/ferrocene-branched chitosan (CHIT-Fc) composites-covered glassy carbon electrode (GCE). The electrochemical behavior of the sensor was investigated in detail by cyclic voltammetry. The apparent surface electron transfer rate constant (K(s)) and charge transfer coefficient (alpha) of the CHIT-Fc/MWCNTs/GCE were also determined by cyclic voltammetry, which were about 1.93 cm s(-1) and 0.42, respectively. The sensor displayed good electrocatalytic activity towards the oxidation of sulfite. The peak potential for the oxidation of sulfite was lowered by at least 330 mV compared with that obtained at CHIT/MWCNTs/GCE. In optimal conditions, linear range spans the concentration of sulfite from 5 microM to 1.5mM and the detection limit was 2.8 microM at a signal-to-noise ratio of 3. The proposed method was used for the determination of sulfite in boiler water. In addition, the sensor has good stability and reproducibility.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Coextraction of acidic, basic and amphiprotic pollutants using multiwalled carbon nanotubes/magnetite nanoparticles@polypyrrole composite.

    PubMed

    Asgharinezhad, Ali Akbar; Ebrahimzadeh, Homeira

    2015-09-18

    The simultaneous extraction of acidic, basic and amphiprotic pollutants from various samples is a considerable and disputable concept in sample preparation strategies. In this study, for the first time, coextraction of acidic, basic and amphiprotic pollutants (polar and apolar) with multiwalled carbon nanotubes/Fe3O4@polypyrrole (MWCNTs/Fe3O4@PPy) composite based dispersive micro-solid phase extraction followed by high performance liquid chromatography-photo diode array detection was introduced. Firstly, the extraction efficiency of various magnetic nanosorbents including Fe3O4, MWCNTs/Fe3O4, graphene oxide/Fe3O4 (GO/Fe3O4), Fe3O4@PPy, MWCNTs/Fe3O4@PPy and GO/Fe3O4@PPy were compared. The results revealed that MWCNTs/Fe3O4@PPy nanocomposite has higher extraction efficiency for five selected model analytes (4-nitrophenol, 3-nitroaniline, 2,4-dichloroaniline, 3,4-dichloroaniline and 1-amino-2-naphthol). Box-Behnken design methodology combined with desirability function approach was applied to find out the optimal experimental conditions. The opted conditions were: pH of the sample, 8.2; sorbent amount, 12 mg; sorption time, 5.5 min; salt concentration, 14% w/w; type and volume of the eluent, 120 μL acetonitrile; elution time; 2 min. Under the optimum conditions detection limits and linear dynamic ranges were achieved in the range of 0.1-0.25 μg L(-1) and 0.5-600 μg L(-1), respectively. The percent of extraction recovery and relative standard deviations (n=5) were in the range of 45.6-82.2 and 4.0-8.5, respectively. Ultimately, the applicability of this method was successfully confirmed by analyzing rain, snow and river water samples and satisfactory results were obtained. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Assembly of well-aligned multiwalled carbon nanotubes in confined polyacrylonitrile environments: electrospun composite nanofiber sheets.

    PubMed

    Ge, Jason J; Hou, Haoqing; Li, Qing; Graham, Matthew J; Greiner, Andreas; Reneker, Darrell H; Harris, Frank W; Cheng, Stephen Z D

    2004-12-08

    Highly oriented, large area continuous composite nanofiber sheets made from surface-oxidized multiwalled carbon nanotubes (MWNTs) and polyacrylonitrile (PAN) were successfully developed using electrospinning. The preferred orientation of surface-oxidized MWNTs along the fiber axis was determined with transmission electron microscopy and electron diffraction. The surface morphology and height profile of the composite nanofibers were also investigated using an atomic force microscope in tapping mode. For the first time, it was observed that the orientation of the carbon nanotubes within the nanofibers was much higher than that of the PAN polymer crystal matrix as detected by two-dimensional wide-angle X-ray diffraction experiments. This suggests that not only surface tension and jet elongation but also the slow relaxation of the carbon nanotubes in the nanofibers are determining factors in the orientation of carbon nanotubes. The extensive fine absorption structure detected via UV/vis spectroscopy indicated that charge-transfer complexes formed between the surface-oxidized nanotubes and negatively charged (-CN[triple bond]N:) functional groups in PAN during electrospinning, leading to a strong interfacial bonding between the nanotubes and surrounding polymer chains. As a result of the highly anisotropic orientation and the formation of complexes, the composite nanofiber sheets possessed enhanced electrical conductivity, mechanical properties, thermal deformation temperature, thermal stability, and dimensional stability. The electrical conductivity of the PAN/MWNT composite nanofibers containing 20 wt % nanotubes was enhanced to approximately 1 S/cm. The tensile modulus values of the compressed composite nanofiber sheets were improved significantly to 10.9 and 14.5 GPa along the fiber winding direction at the MWNT loading of 10 and 20 wt %, respectively. The thermal deformation temperature increased with increased MWNT loading. The thermal expansion coefficient of the

  10. Enhanced microwave shielding and mechanical properties of multiwall carbon nanotubes anchored carbon fiber felt reinforced epoxy multiscale composites

    NASA Astrophysics Data System (ADS)

    Singh, B. P.; Bharadwaj, Preetam; Choudhary, Veena; Mathur, R. B.

    2014-04-01

    Multi-walled carbon nanotubes (MWCNTs) were grown on carbon fiber (CF) felt by chemical vapor deposition that resulted into strongly anchored carbon nanotubes (CNTs) on the CF surface. These multiscale preforms were used as the reinforcement in epoxy resin to develop multi scale CF felt-MWCNT/epoxy composites. The flexural strength (FS) and the flexural modulus (FM) of the composites were found to increase with increasing amount of CNTs grown on CF felt surface. FS improved by 37 %, i.e. 119 MPa compared to 87 MPa for CF felt/epoxy composites prepared under identical conditions. The FM also improved by 153 %, i.e. 15.7 GPa compared to 6.2 GPa for the CF/epoxy composites. The incorporation of MWCNTs on the CF felt produced a significant change in the electromagnetic interference shielding of these composites which improved from -21 to -27 dB for CF felt-MWCNT/epoxy multiscale composites in the Ku band (12.4-18 GHz) and indicates the usefulness of these strong composites for microwave shielding.

  11. Optical properties of carbon nanostructures produced by laser irradiation on chemically modified multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Santiago, Enrique Vigueras; López, Susana Hernández; Camacho López, Marco A.; Contreras, Delfino Reyes; Farías-Mancilla, Rurik; Flores-Gallardo, Sergio G.; Hernández-Escobar, Claudia A.; Zaragoza-Contreras, E. Armando

    2016-10-01

    This research focused on the nanosecond (Nd: YAG-1064 nm) laser pulse effect on the optical and morphological properties of chemically modified multi-walled carbon nanotubes (MWCNT). Two suspensions of MWCNT in tetrahydrofuran (THF) were prepared, one was submitted to laser pulses for 10 min while the other (blank) was only mechanically homogenized during the same time. Following the laser irradiation, the suspension acquired a yellow-amber color, in contrast to the black translucent appearance of the blank. UV-vis spectroscopy confirmed this observation, showing the blank a higher absorption. Additionally, photoluminescence measurements exhibited a broad blue-green emission band both in the blank and irradiated suspension when excited at 369 nm, showing the blank a lower intensity. However, a modification in the excitation wavelength produced a violet to green tuning in the irradiated suspension, which did not occur in the blank. Lastly, the electron microscopy analysis of the treated nanotubes showed the abundant formation of amorphous carbon, nanocages, and nanotube unzipping, exhibiting the intense surface modification produced by the laser pulse. Nanotube surface modification and the coexistence with the new carbon nanostructures were considered as the conductive conditions for optical properties modification.

  12. Boron Doping of Multiwalled Carbon Nanotubes Significantly Enhances Hole Extraction in Carbon-Based Perovskite Solar Cells.

    PubMed

    Zheng, Xiaoli; Chen, Haining; Li, Qiang; Yang, Yinglong; Wei, Zhanhua; Bai, Yang; Qiu, Yongcai; Zhou, Dan; Wong, Kam Sing; Yang, Shihe

    2017-04-12

    Compared to the conventional perovskite solar cells (PSCs) containing hole-transport materials (HTM), carbon materials based HTM-free PSCs (C-PSCs) have often suffered from inferior power conversion efficiencies (PCEs) arising at least partially from the inefficient hole extraction at the perovskite-carbon interface. Here, we show that boron (B) doping of multiwalled carbon nanotubes (B-MWNTs) electrodes are superior in enabling enhanced hole extraction and transport by increasing work function, carrier concentration, and conductivity of MWNTs. The C-PSCs prepared using the B-MWNTs as the counter electrodes to extract and transport hole carriers have achieved remarkably higher performances than that with the undoped MWNTs, with the resulting PCE being considerably improved from 10.70% (average of 9.58%) to 14.60% (average of 13.70%). Significantly, these cells show negligible hysteretic behavior. Moreover, by coating a thin layer of insulating aluminum oxide (Al 2 O 3 ) on the mesoporous TiO 2 film as a physical barrier to substantially reduce the charge losses, the PCE has been further pushed to 15.23% (average 14.20%). Finally, the impressive durability and stability of the prepared C-PSCs were also testified under various conditions, including long-term air exposure, heat treatment, and high humidity.

  13. 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.

  14. Photothermal Response of Human and Murine Cancer Cells to Multiwalled Carbon Nanotubes after Laser Irradiation

    PubMed Central

    Fisher, Jessica W.; Sarkar, Saugata; Buchanan, Cara F.; Szot, Christopher S.; Whitney, Jon; Hatcher, Heather C.; Torti, Suzy V.; Rylander, Christopher G.; Rylander, Marissa Nichole

    2013-01-01

    This study demonstrates the capability of multiwalled carbon nanotubes (MWNTs) coupled with laser irradiation to enhance treatment of cancer cells through enhanced and more controlled thermal deposition, increased tumor injury, and diminished heat shock protein (HSP) expression. We also explored the potential promise of MWNTs as drug delivery agents by observing the degree of intracellular uptake of these nanoparticles. To determine the heat generation capability of MWNTs, the absorption spectra and temperature rise during heating were measured. Higher optical absorption was observed for MWNTs in water compared with water alone. For identical laser parameters, MWNT-containing samples produced a significantly greater temperature elevation compared to samples treated with laser alone. Human prostate cancer (PC3) and murine renal carcinoma (RENCA) cells were irradiated with a 1,064-nm laser with an irradiance of 15.3 W/cm2 for 2 heating durations (1.5 and 5 minutes) alone or in combination with MWNT inclusion. Cytotoxicity and HSP expression following laser heating was used to determine the efficacy of laser treatment alone or in combination with MWNTs. No toxicity was observed for MWNTs alone. Inclusion of MWNTs dramatically decreased cell viability and HSP expression when combined with laser irradiation. MWNT cell internalization was measured using fluorescence and transmission electron microscopy following incubation of MWNTs with cells. With increasing incubation duration, a greater number of MWNTs were observed in cellular vacuoles and nuclei. These findings offer an initial proof of concept for the application of MWNTs in cancer therapy. PMID:21098701

  15. 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

  16. Biosynthesis of Bacterial Cellulose/Carboxylic Multi-Walled Carbon Nanotubes for Enzymatic Biofuel Cell Application.

    PubMed

    Lv, Pengfei; Feng, Quan; Wang, Qingqing; Li, Guohui; Li, Dawei; Wei, Qufu

    2016-03-09

    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.

  17. 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.

  18. 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.

  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. 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.

  1. 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.

  2. 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.

  3. Enzyme Immobilisation on Amino-Functionalised Multi-Walled Carbon Nanotubes: Structural and Biocatalytic Characterisation

    PubMed Central

    Verma, Madan L.; Naebe, Minoo; Barrow, Colin J.; Puri, Munish

    2013-01-01

    Background The aim of this work is to investigate the structure and function of enzymes immobilised on nanomaterials. This work will allow better understanding of enzyme-nanomaterial interactions, as well as designing functional protein-nanomaterial conjugates. Methodology/Principal Findings Multiwalled carbon nanotubes (MWNTs) were functionalised with amino groups to improve solubility and biocompatibility. The pristine and functionalised forms of MWNTs were characterised with Fourier-transform infrared spectroscopy. Thermogravimetric analysis was done to examine the degree of the functionalisation process. An immobilised biocatalyst was prepared on functionalised nanomaterial by covalent binding. Thermomyces lanuginosus lipase was used as a model enzyme. The structural change of the immobilised and free lipases were characterised with transmission electron Microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy and Circular dichroism spectroscopy. Biochemical characterisation of immobilised enzyme showed broader pH and thermal optima compared to soluble form. Reusability of the immobilised enzyme for hydrolysis of long chain esters was demonstrated up to ten cycles. Conclusion/Significance Lipase immobilised on MWNTs has exhibited significantly improved thermal stability. The exploration of advanced nanomaterial for enzyme immobilisation support using sophisticated techniques makes nanobiocatalyst of potential interest for biosensor applications. PMID:24069216

  4. Morphological Features and Melting Behavior of Nanocomposites Based on Isotactic Polypropylene and Multiwalled Carbon Nanotubes

    SciTech Connect

    Avila-Orta,C.; Medellin-Rodriguez, F.; Davila-Rodriguez, M.; Aguirre-Figueroa, Y.; Yoon, K.; Hsiao, B.

    2007-01-01

    Nanocomposites based on low molar mass isotactic polypropylene (iPP) and a low concentrations (1-2 wt %) of multiwalled carbon nanotubes (MWCNTs) were studied using thermal analysis, optical and electronic microscopy, and X-ray diffraction/scattering techniques. It was first determined that MWCNT decrease induction time and act as nucleating agents of the iPP crystals during nonisothermal crystallization. One of the consequences of the nucleation effect was that the original spherulitic morphology of iPP was transformed into a fibrillar-like. The corresponding long period of the original well-defined lamellar structure slightly increased suggesting the formation of thicker crystals in samples containing MWCNT. The nature of the {alpha}-iPP crystalline structure was not affected by MWCNT. After nonisothermal crystallization, two melting endotherms were present during thermal scanning of the iPP/MWCNT nanocomposites their proportion changing with the heating rate. After resolving the total DSC signal in its components using MDSC, the overall evolution of such behavior could be explained in terms of the melting/recrystallization mechanism.

  5. 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.

  6. 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.

  7. 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.

  8. Electrochemical study of the Pt and Pt-Ni upon multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Mohammed, Norani Muti; Mumtaz, Asad; Ansari, Muhammad Shahid; Ahmad, Riaz

    2016-11-01

    Direct methanol fuel cells have attracted great interest in the recent development of portable devices. New routes are being developed for synthesizing the catalysts used in the methanol oxidation. In this work, the electrochemical behavior of the Pt and Pt-Ni upon multiwalled carbon nanotubes, synthesized via a new modified route, has been studied. The results showed that Pt-Ni 10% has the comparable current density to the Pt 20%-loading which is nearly 3 times greater than 10% Pt loading. The transfer of the polarization curve of Pt-Ni 10% towards lower polarization region following the catalyst with 20% Pt loading indicates the higher activity of the nano-electro-catalysts in the alkaline media. Also the long term efficiency and activity of the Pt-Ni with 10% loading is nearly reaching the 20% Pt-loading which is almost 10 folds greater than the 10% Pt loading. The study revealed that Ni in Pt-based nanoalloy impart not only an enhanced activity but also better durability of catalyst in direct methanol fuel cell applications.

  9. Facile chemical route for multiwalled carbon nanotube/mercury sulfide nanocomposite: High performance supercapacitive electrode.

    PubMed

    Pande, Shilpa A; Pandit, Bidhan; Sankapal, Babasaheb R

    2017-12-27

    Supercapacitors as one of the most important energy storage devices have been receiving worldwide attention due to their high capacitance, power density, long cycle life, and rapid charge/discharge rates as compared to conventional electrolytic capacitors and rechargeable batteries. A nanocomposite has been prepared using mercury sulfide (HgS) and multiwalled carbon nanotubes (MWCNTs) via novel, simple, and low-cost 'dip and dry' process followed by successive ionic layer adsorption and reaction (SILAR) method. The association of HgS nanoparticles with high surface area reinforced MWCNTs nanonetwork boosts the electrochemical supercapacitive performance of nanocomposite compared to bare HgS and MWCNTs. This nanocomposite yields excellent specific capacitance of 946.43 F/g at scan rate of 2 mV/s and an outstanding rate capability of 93% retention over 4000 cycles with decent charge-discharge cycles. Moreover, the electrode exhibits maximum specific energy and power densities of 42.97 Wh/kg and 1.60 kW/kg, respectively. The promising capabilities of formed nanocomposite can explore the opportunities as alternative electrode material for energy storage applications. Copyright © 2017. Published by Elsevier Inc.

  10. Mechanical properties and deformation morphologies of covalently bridged multi-walled carbon nanotubes: Multiscale modeling

    NASA Astrophysics Data System (ADS)

    Huang, Xu; Yuan, Hongyan; Liang, Wentao; Zhang, Sulin

    2010-11-01

    We formulate a multiscale modeling framework to investigate the deformation morphologies and energetics of covalently bridged multi-walled carbon nanotubes (MWCNTs). The formulation involves extending a previously established quasi-continuum model by incorporating the inter-wall bridging energy density function into the constitutive relations via message passing from fully atomistic simulations. Using the extended numerical model, we studied the mechanical responses of the 10-walled MWCNT with varying inter-wall bridge densities under torsion, bending, and uniaxial compression. Our simulation results show that the presence of inter-wall covalent bridges not only enhances the post-buckling rigidities of the MWCNTs, but also modifies the deformation morphologies and morphology pathways. For bending and uniaxial compression, we constructed in the space of bridge density and applied strain the deformation morphology phase diagram, where three phases, uniformly deformed phase, rippling pattern, and diamond-shaped pattern, are identified and separated by linear phase boundaries. We attribute the deformation phase transitions to the interplay of inter-wall and intra-wall interaction energies. The multiple shape transitions of MWCNTs and the elastic nature of the deformation suggest that MWCNTs can be designed as shape-memory nanodevices with tunable stabilities.

  11. Heteroaggregation of Multiwalled Carbon Nanotubes and Hematite Nanoparticles: Rates and Mechanisms

    PubMed Central

    Huynh, Khanh An; McCaffery, J. Michael; Chen, Kai Loon

    2012-01-01

    The heteroaggregation rates of negatively charged multiwalled carbon nanotubes (CNTs) and positively charged hematite nanoparticles (HemNPs) were obtained over a broad range of nanoparticle distributions using time-resolved dynamic light scattering (DLS). Binary systems comprising CNTs and HemNPs were prepared using low ionic strength solutions to minimize the concurrent occurrence of homoaggregation. In order to elucidate the mechanisms of heteroaggregation, the structures of CNT–HemNP aggregates were observed using cryogenic transmission electron microscopy (cryo-TEM). An initial increase in the CNT concentration, while keeping the HemNP concentration constant, resulted in a corresponding increase in the rate of heteroaggregation which occurred through the bridging of HemNPs by CNT strands. At the optimal CNT/HemNP mass concentration ratio of 0.0316, the heteroaggregation rate reached 3.3 times of the HemNP homoaggregation rate in the diffusion-limited regime. Increasing the CNT/HemNP ratio above the optimal value, however, led to a dramatic decrease in the growth rate of heteroaggregates, likely through a blocking mechanism. In the presence of humic acid, the trends in the variation of the heteroaggregation rate with CNT/HemNP ratio were similar to that in the absence of humic acid. However, as the humic acid concentration was increased, the maximum aggregate growth rate decreased due to the lessening in the available surface of the HemNPs that CNTs can attach to through favorable electrostatic interaction. PMID:22545989

  12. Effect of Multi-walled Carbon Nanotubes on Metabolism and Morphology of Filamentous Green Microalgae.

    PubMed

    Munk, Michele; Brandão, Humberto M; Yéprémian, Claude; Couté, Alain; Ladeira, Luiz O; Raposo, Nádia R B; Brayner, Roberta

    2017-11-01

    Multi-walled carbon nanotubes (MWCNTs) have potential applications in the industrial, agricultural, pharmaceutical, medical, and environmental remediation fields. However, many uncertainties exist regarding the environmental implications of engineered nanomaterials. This study examined the effect of the MWCNTs on metabolic status and morphology of filamentous green microalgae Klebsormidium flaccidum. Appropriate concentrations of MWCNT (1, 50, and 100 μg mL-1) were added to a microalgal culture in the exponential growth phase and incubated for 24, 48, 72, and 96 h. Exposure to MWCNT led to reductions in algal growth after 48 h and decreased on cell viability for all experimental endpoints except for 1 µg mL-1 at 24 h and 100 µg mL-1 after 72 h. At 100 µg mL-1, MWCNTs induced reactive oxygen species (ROS) production and had an effect on intracellular adenosine triphosphate (ATP) content depending on concentration and time. No photosynthetic activity variation was observed. Observations by scanning transmission electron microscopy showed cell damage. In conclusion, we have demonstrated that exposure to MWCNTs affects cell metabolism and microalgal cell morphology. To our best knowledge, this is the first case in which MWCNTs exhibit adverse effects on filamentous green microalgae K. flaccidum. These results contribute to elucidate the mechanism of MWCNT nanotoxicity in the bioindicator organism of terrestrial and freshwater habitats.

  13. 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.

  14. Acute pulmonary dose-responses to inhaled multi-walled carbon nanotubes.

    PubMed

    Porter, Dale W; Hubbs, Ann F; Chen, Bean T; McKinney, Walter; Mercer, Robert R; Wolfarth, Michael G; Battelli, Lori; Wu, Nianqiang; Sriram, Krishnan; Leonard, Stephen; Andrew, Michael; Willard, Patsy; Tsuruoka, Shuji; Endo, Morinobu; Tsukada, Takayuki; Munekane, Fuminori; Frazer, David G; Castranova, Vincent

    2013-11-01

    This study investigated the in vivo pulmonary toxicity of inhaled multi-walled carbon nanotubes (MWCNT). Mice-inhaled aerosolized MWCNT (10 mg/m³, 5 h/day) for 2, 4, 8 or 12 days. MWCNT lung burden was linearly related to exposure duration. MWCNT-induced pulmonary inflammation was assessed by determining whole lung lavage (WLL) polymorphonuclear leukocytes (PMN). Lung cytotoxicity was assessed by WLL fluid LDH activities. WLL fluid albumin concentrations were determined as a marker of alveolar air-blood barrier integrity. These parameters significantly increased in MWCNT-exposed mice versus controls and were dose-dependent. Histopathologic alterations identified in the lung included (1) bronciolocentric inflammation, (2) bronchiolar epithelial hyperplasia and hypertrophy, (3) fibrosis, (4) vascular changes and (5) rare pleural penetration. MWCNT translocated to the lymph node where the deep paracortex was expanded after 8 or 12 days. Acute inhalation of MWCNT induced dose-dependent pulmonary inflammation and damage with rapid development of pulmonary fibrosis, and also demonstrated that MWCNT can reach the pleura after inhalation exposure.

  15. 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.

  16. Enhanced NO2 Gas Sensing Properties of WO3-Coated Multiwall Carbon Nanotube Sensors.

    PubMed

    Ko, Hyunsung; Park, Sunghoon; Park, Suyoung; Lee, Chongmu

    2015-07-01

    WO3-coated multiwall carbon nanotubes (MWCNTs) were fabricated by sputter-deposition of WO3 on MWCNT paste. The outer diameters of WO3-coated MWCNTs ranged from 20 to 40 nm and the lengths ranged up to a few tens of micrometers. The low-magnification TEM image of a typical WO3-coated CNT showed a CNT with an inner diameter of ~20 nm and a tube wall thickness of ~7 nm and WO3 shells with a thickness up to 10 nm at both edges of the tube. The WO3 shells were very nonuniform in thickness not only along the axis of the nanotube but also from one nanotube to the other. The sensing properties of multiple networked WO3-coated CNT sensors toward NO2 gas were examined. The WO3-coated MWCNT sensors showed responses of 120-221% over an NO2 concentration range of 1 to 5 ppm at room temperature. The responses were 1-2 fold higher than those of the pristine MWCNT sensor over the same NO2 concentration range. The origin of the enhancement of the MWCNTs in the response to NO2 by coating them with WO3 is discussed.

  17. Greater osteoblast functions on multiwalled carbon nanotubes grown from anodized nanotubular titanium for orthopedic applications

    NASA Astrophysics Data System (ADS)

    Sirivisoot, Sirinrath; Yao, Chang; Xiao, Xingcheng; Sheldon, Brian W.; Webster, Thomas J.

    2007-09-01

    Titanium (Ti) is the most widely implanted orthopedic material. However, current formulations of Ti have an average orthopedic implant functional lifetime of only 10-15 years. While there are many reasons why orthopedic implants fail, one is a lack of initial and sustained integration into juxtaposed bone. To improve the cytocompatibility properties of Ti for orthopedic applications, parallel multiwalled carbon nanotubes (CNTs) were grown from the pores of anodized nanotubular Ti by a chemical vapor deposition process in the present study. The results of this study provided evidence, for the first time, that osteoblast (bone forming cell) functions (specifically, alkaline phosphatase activity and calcium deposition) were significantly greater on CNTs grown from anodized Ti than on anodized Ti without CNTs and currently-used Ti in orthopedics for up to 21 days. In summary, this study showed that bone growth could possibly be enhanced on currently-used Ti implants with protruding CNTs and, thus, they should be further studied for orthopedic applications.

  18. Detection of organophosphorous pesticides in soil samples with multiwalled carbon nanotubes coating SPME fiber.

    PubMed

    Feng, Xilan; Li, Ying; Jing, Ruijun; Jiang, Xiaoying; Tian, Mengkui

    2014-12-01

    A headspace solid phase microextraction (HS-SPME) technique using stainless steel fiber coated with 20 μm multi-walled carbon nanotubes (MWCNTs) and gas chromatography with thermionic specific detector (GC-TSD) was developed to determine organophosphorous pesticides (OPPs) in soil. Parameters affecting the extraction efficiency such as extraction time and temperature, ionic strength, the volume of water added to the soil, sample solution volume to headspace volume ratio, desorption time, and desorption temperature were investigated and optimized. Compared to commercial polydimethylsiloxane (PDMS, 7 μm) fiber, the PDMS fiber was better to be corrected as phorate, whereas the MWCNTs fiber gave slightly better results for methyl parathion, chlorpyrifos and parathion. The optimized SPME method was applied to analyze OPPs in spiked soil samples. The limits of detection (LODs, S/N = 3) for the four pesticides were <0.216 ng g(-1), and their calibration curves were all linear (r (2) ≥ 0.9908) in the range from 1 to 200 ng g(-1). The precision (RSD, n = 6) for peak areas was 6.5 %-8.8 %. The recovery of the OPPs spiked real soil samples at 50 and 150 ng g(-1) ranged from 89.7 % to 102.9 % and 94.3 % to 118.1 %, respectively.

  19. Spray-Coated Multiwalled Carbon Nanotube Composite Electrodes for Thermal Energy Scavenging Electrochemical Cells.

    PubMed

    Holubowitch, Nicolas E; Landon, James; Lippert, Cameron A; Craddock, John D; Weisenberger, Matthew C; Liu, Kunlei

    2016-08-31

    Spray-coated multiwalled carbon nanotube/poly(vinylidene fluoride) (MWCNT/PVDF) composite electrodes, scCNTs, with varying CNT compositions (2 to 70 wt %) are presented for use in a simple thermal energy-scavenging cell (thermocell) based on the ferro/ferricyanide redox couple. Their utility for direct thermal-to-electrical energy conversion is explored at various temperature differentials and cell orientations. Performance is compared to that of buckypaper, a 100% CNT sheet material used as a benchmark electrode in thermocell research. The 30 to 70 wt % scCNT composites give the highest power output by electrode area-seven times greater than buckypaper at ΔT = 50 °C. CNT utilization is drastically enhanced in our electrodes, reaching 1 W gCNT(-1) compared to 0.036 W gCNT(-1) for buckypaper. Superior performance of our spray-coated electrodes is attributed to both wettability with better use of a large portion of electrochemically active CNTs and minimization of ohmic and thermal contact resistances. Even composites with as low as 2 wt % CNTs are still competitive with prior art. The MWCNT/PVDF composites developed herein are inexpensive, scalable, and serve a general need for CNT electrode optimization in next-generation devices.

  20. Enhanced field emission from lanthanum hexaboride coated multiwalled carbon nanotubes: Correlation with physical properties

    SciTech Connect

    Patra, Rajkumar; Ghosh, S., E-mail: santanu1@physics.iitd.ac.in; Sheremet, E.

    2014-10-28

    Detailed results from field emission studies of lanthanum hexaboride (LaB{sub 6}) coated multiwalled carbon nanotube (MWCNT) films, pristine LaB{sub 6} films, and pristine MWCNT films are reported. The films have been synthesized by a combination of chemical and physical deposition processes. An impressive increase in field enhancement factor and temporal stability as well as a reduction in turn-on field and threshold field are observed in LaB{sub 6}-coated MWCNTs compared to pristine MWCNT and pristine LaB{sub 6} films. Surface morphology of the films has been examined by scanning electron microscopy. Introduction of LaB{sub 6} nanoparticles on the outer walls of CNTsmore » LaB{sub 6}-coated MWCNTs films is confirmed by transmission electron microscopy. The presence of LaB{sub 6} was confirmed by X-ray photoelectron spectroscopy results and further validated by the Raman spectra. Raman spectroscopy also shows 67% increase in defect concentration in MWCNTs upon coating with LaB{sub 6} and an upshift in the 2D band that could be attributed to p-type doping. Ultraviolet photoelectron spectroscopy studies reveal a reduction in the work function of LaB{sub 6}-coated MWCNT with respect to its pristine counterpart. The enhanced field emission properties in LaB{sub 6}-coated MWCNT films are correlated with a change in microstructure and work function.« less

  1. Laccase immobilization over multi-walled carbon nanotubes: Kinetic, thermodynamic and stability studies.

    PubMed

    Tavares, Ana P M; Silva, Cláudia G; Dražić, Goran; Silva, Adrián M T; Loureiro, José M; Faria, Joaquim L

    2015-09-15

    The biocatalytic performance of immobilized enzyme systems depends mostly on the intrinsic properties of both biomolecule and support, immobilization technique and immobilization conditions. Multi-walled carbon nanotubes (MWCNTs) possess unique features for enzyme immobilization by adsorption. Enhanced catalytic activity and stability can be achieved by optimization of the immobilization conditions and by investigating the effect of operational parameters. Laccase was immobilized over MWCNTs by adsorption. The hybrid material was characterized by Fourier transformed infrared (FTIR) spectroscopy, scanning and transmission electron microscopy (SEM and TEM, respectively). The effect of different operational conditions (contact time, enzyme concentration and pH) on laccase immobilization was investigated. Optimized conditions were used for thermal stability, kinetic, and storage and operational stability studies. The optimal immobilization conditions for a laccase concentration of 3.75μL/mL were a pH of 9.0 and a contact time of 30min (522 Ulac/gcarrier). A decrease in the thermal stability of laccase was observed after immobilization. Changes in ΔS and ΔH of deactivation were found for the immobilized enzyme. The Michaelis-Menten kinetic constant was higher for laccase/MWCNT system than for free laccase. Immobilized laccase maintained (or even increased) its catalytic performance up to nine cycles of utilization and revealed long-term storage stability. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Response of methane production via propionate oxidation to carboxylated multiwalled carbon nanotubes in paddy soil enrichments

    PubMed Central

    Zhang, Jianchao; Xia, Xingxuan; Li, Siliang

    2018-01-01

    Carboxylated multiwalled carbon nanotubes (MWCNTs-COOH) have become a growing concern in terms of their fate and toxicity in aqueous environments. Methane (CH4) is a major product of organic matter degradation in waterlogged environments. In this study, we determined the effect of MWCNTs-COOH on the production of CH4 from propionate oxidation in paddy soil enrichments. The results showed that the methanogenesis from propionate degradation was accelerated in the presence of MWCNTs-COOH. In addition, the rates of CH4 production and propionate degradation increased with increasing concentrations of MWCNTs-COOH. Scanning electron microscopy (SEM) observations showed that the cells were intact and maintained their structure in the presence of MWCNTs-COOH. In addition, SEM and fluorescence in situ hybridization (FISH) images revealed that the cells were in direct contact with the MWCNTs and formed cell-MWCNTs aggregates that contained both bacteria and archaea. On the other hand, nontoxic magnetite nanoparticles (Fe3O4) had similar effects on the CH4 production and cell integrity as the MWCNTs-COOH. Compared with no nanomaterial addition, the relative abundances of Geobacter and Methanosarcina species increased in the presence of MWCNTs-COOH. This study suggests that MWCNTs-COOH exerted positive rather than cytotoxic effects on the syntrophic oxidation of propionate in paddy soil enrichments and affected the bacterial and archaeal community structure at the test concentrations. These findings provide novel insight into the consequences of nanomaterial release into anoxic natural environments. PMID:29340254

  3. 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.

  4. Damaging Effects of Multi-walled Carbon Nanotubes on Pregnant Mice with Different Pregnancy Times

    PubMed Central

    Qi, Wei; Bi, Juanjuan; Zhang, Xiaoyong; Wang, Jing; Wang, Jianjun; Liu, Peng; Li, Zhan; Wu, Wangsuo

    2014-01-01

    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. PMID:24619025

  5. 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

  6. Strengthening behavior of chopped multi-walled carbon nanotube reinforced aluminum matrix composites

    SciTech Connect

    Shin, S.E.; Bae, D.H.

    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 be 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.

  7. Modified multi-walled carbon nanotubes potentially suitable for intracellular pH measurements

    NASA Astrophysics Data System (ADS)

    Ghini, Giacomo; Puleo, Gian Luigi; Trono, Cosimo; Giannetti, Ambra; Luconi, Lapo; Bianchini, Claudio; Giambastiani, Giuliano; Baldini, Francesco

    2010-02-01

    Carboxylic acid functionalized multi-walled carbon nanotubes (COOH-MWCNTs) have been studied as macromolecular carriers for pH indicators to be used inside cells. The activation of carboxylic groups with thionyl chloride (SOCl2) followed by the reaction with a family of fluorescein ethylen glycol derivatives led to dyes covalently anchored to the MWCNT surface. Such a functionalization was found to preserve wholly the fluorescence properties of the dye ultimately providing higher water solubility to the modified macromolecular systems. Moreover, the use of a polyether spacer between the dye and the MWCNT surface preserved from undesired florescence quenching effects. The pH dependence of the modified nanotubes was investigated interrogating a solution of MWCNTs, the pH of which was adjusted in the range 4-9 pH units by adding drops of hydrochloric acid and sodium hydroxide. Light from LED was suitably filtered at 480 nm with a high pass-band filter and coupled to an optical fiber which illuminates the solution containing the fluorescein-functionalised MWCNTs. An optical fiber, at 90° with respect to the LED illumination, is connected with a Hamamtsu spectrum analyzer for the recording of the fluorescence spectra. The modified MWCNTs exhibited linear pH dependence in the range between 6 and 8 pH units with a sensitivity less than 0.1 pH units.

  8. Preparation of transparent conductive multilayered films using active pentafluorophenyl ester modified multiwalled carbon nanotubes.

    PubMed

    Park, Hye Jin; Kim, Junkyung; Chang, Ji Young; Theato, Patrick

    2008-09-16

    A multilayered film was prepared by layer-by-layer (LBL) assembly of active ester modified multiwalled carbon nanotubes (MWCNTs) and poly(allylamine hydrochloride) (PAH). For this purpose, carboxylic groups on the surface of the oxidized MWCNTs were converted to the acyl chlorides by their reaction with thionyl chloride. Subsequent reaction of the acyl chlorides with pentafluorophenol formed the active esters. These active ester modified MWCNTs (MWCNTs-COOC(6)F(5)) were air-stable and moisture resistant, but showed a high reactivity toward primary or secondary amines resulting in amide bonds. For the preparation of a multilayered film, the surface of a quartz slide was first activated and sacrificial double layers of PAH and poly(sodium 4-styrene sulfonate) (PSS) were deposited. Subsequently, LBL assembly of MWCNTs-COOC(6)F(5) and PAH was then conducted on these double layers [(PAH/PSS)2]. In the process of the assembly, a reaction occurred between the active ester on the surface of MWCNTs and the amine groups of polyallylamine yielding amide bonds, which resulted in a mechanically stable thin film. A free-standing film was obtained after dissolving the sacrificial layer [(PAH/PSS)2] in a concentrated aqueous NaOH solution. The surface resistance of the multilayered film with 20 bilayers decreased to around 10 kOmega while remaining a reasonable transparency (70% at 500 nm).

  9. 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.

  10. The effect of multi-wall carbon nanotubes on electromagnetic interference shielding of ceramic composites.

    PubMed

    Shi, Sui-Lin; Liang, Ji

    2008-06-25

    Multi-wall carbon nanotubes (MWCNTs)-3 mol% yttria-stabilized zirconia (3Y-TZP) (MWCNTs-3Y-TZP) composite was prepared by spark plasma sintering. The complex permittivities of the composite have been measured in the Ku-band range (12.4-18 GHz) and it is found that both the real and imaginary permittivities of the composite increase with the increasing content of MWCNTs. The effect of the content of MWCNTs on the electromagnetic interference (EMI) shielding effectiveness (SE) of the composite has been evaluated, and it is found that the EMI SE of the composite increases with the increasing content of MWCNTs. An EMI SE value as high as 25-30 dB has been achieved in the Ku-band range for the composite with 9 wt% content of MWCNTs, indicating that the MWCNTs-3Y-TZP composite can be used as an effective EMI shielding material.

  11. Multi-walled carbon nanotube instillation impairs pulmonary function in C57BL/6 mice.

    PubMed

    Wang, Xiaojia; Katwa, Pranita; Podila, Ramakrishna; Chen, Pengyu; Ke, Pu Chun; Rao, Apparao M; Walters, Dianne M; Wingard, Christopher J; Brown, Jared M

    2011-08-18

    Multi-walled carbon nanotubes (MWCNTs) are widely used in many disciplines due to their unique physical and chemical properties. Therefore, some concerns about the possible human health and environmental impacts of manufactured MWCNTs are rising. We hypothesized that instillation of MWCNTs impairs pulmonary function in C57BL/6 mice due to development of lung inflammation and fibrosis. MWCNTs were administered to C57BL/6 mice by oropharyngeal aspiration (1, 2, and 4 mg/kg) and we assessed lung inflammation and fibrosis by inflammatory cell infiltration, collagen content, and histological assessment. Pulmonary function was assessed using a FlexiVent system and levels of Ccl3, Ccl11, Mmp13 and IL-33 were measured by RT-PCR and ELISA. Mice administered MWCNTs exhibited increased inflammatory cell infiltration, collagen deposition and granuloma formation in lung tissue, which correlated with impaired pulmonary function as assessed by increased resistance, tissue damping, and decreased lung compliance. Pulmonary exposure to MWCNTs induced an inflammatory signature marked by cytokine (IL-33), chemokine (Ccl3 and Ccl11), and protease production (Mmp13) that promoted the inflammatory and fibrotic changes observed within the lung. These results further highlight the potential adverse health effects that may occur following MWCNT exposure and therefore we suggest these materials may pose a significant risk leading to impaired lung function following environmental and occupational exposures.

  12. Multi-walled carbon nanotube instillation impairs pulmonary function in C57BL/6 mice

    PubMed Central

    2011-01-01

    Background Multi-walled carbon nanotubes (MWCNTs) are widely used in many disciplines due to their unique physical and chemical properties. Therefore, some concerns about the possible human health and environmental impacts of manufactured MWCNTs are rising. We hypothesized that instillation of MWCNTs impairs pulmonary function in C57BL/6 mice due to development of lung inflammation and fibrosis. Methods MWCNTs were administered to C57BL/6 mice by oropharyngeal aspiration (1, 2, and 4 mg/kg) and we assessed lung inflammation and fibrosis by inflammatory cell infiltration, collagen content, and histological assessment. Pulmonary function was assessed using a FlexiVent system and levels of Ccl3, Ccl11, Mmp13 and IL-33 were measured by RT-PCR and ELISA. Results Mice administered MWCNTs exhibited increased inflammatory cell infiltration, collagen deposition and granuloma formation in lung tissue, which correlated with impaired pulmonary function as assessed by increased resistance, tissue damping, and decreased lung compliance. Pulmonary exposure to MWCNTs induced an inflammatory signature marked by cytokine (IL-33), chemokine (Ccl3 and Ccl11), and protease production (Mmp13) that promoted the inflammatory and fibrotic changes observed within the lung. Conclusions These results further highlight the potential adverse health effects that may occur following MWCNT exposure and therefore we suggest these materials may pose a significant risk leading to impaired lung function following environmental and occupational exposures. PMID:21851604

  13. 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

  14. Endocytosis of Multiwalled Carbon Nanotubes in Bronchial Epithelial and Mesothelial Cells

    PubMed Central

    Maruyama, Kayo; Matsuda, Yoshikazu; Kobayashi, Shinsuke; Tanaka, Manabu; Aoki, Kaoru; Takanashi, Seiji; Okamoto, Masanori; Kato, Hiroyuki

    2015-01-01

    Bronchial epithelial cells and mesothelial cells are crucial targets for the safety assessment of inhalation of carbon nanotubes (CNTs), which resemble asbestos particles in shape. Intrinsic properties of multiwalled CNTs (MWCNTs) are known to cause potentially hazardous effects on intracellular and extracellular pathways. These interactions alter cellular signaling and affect major cell functions, resulting in cell death, lysosome injury, reactive oxygen species production, apoptosis, and cytokine release. Furthermore, CNTs are emerging as a novel class of autophagy inducers. Thus, in this study, we focused on the mechanisms of MWCNT uptake into the human bronchial epithelial cells (HBECs) and human mesothelial cells (HMCs). We verified that MWCNTs are actively internalized into HBECs and HMCs and were accumulated in the lysosomes of the cells after 24-hour treatment. Next, we determined which endocytosis pathways (clathrin-mediated, caveolae-mediated, and macropinocytosis) were associated with MWCNT internalization by using corresponding endocytosis inhibitors, in two nonphagocytic cell lines derived from bronchial epithelial cells and mesothelioma cells. Clathrin-mediated endocytosis inhibitors significantly suppressed MWCNT uptake, whereas caveolae-mediated endocytosis and macropinocytosis were also found to be involved in MWCNT uptake. Thus, MWCNTs were positively taken up by nonphagocytic cells, and their cytotoxicity was closely related to these three endocytosis pathways. PMID:26090445

  15. Multi-walled carbon nanotubes facilitated the removal of tetrabromobisphenol a mediated by horseradish peroxidase.

    PubMed

    Lu, Kun; Hu, Jinyuan; Gao, Shixiang; Mao, Liang

    2017-12-01

    In this study, we systematically investigated the effect of multiwall carbon nanotubes (MWCNTs) on the removal of tetrabromobisphenol A (TBBPA) mediated by horseradish peroxidase (HRP) at varying important conditions. The results suggested that the presence of MWCNTs significantly enhanced the removal of TBBPA mediated by HRP and the reaction rate constant was linear with the MWCNTs dosage. The enhancement of MWCNTs on the HRP-mediated reaction was attributed to two facts, one is that MWCNTs protected HRP from inactivation, the other is that the presence of MWCNTs made the homogeneous reaction of TBBPA be heterogeneous reaction by adsorbing TBBPA on its surface. Moreover, the influence of MWCNTs on TBBPA products distribution was further elucidated. We found that the species of reaction product had no difference between the HRP-mediated systems with and without the presence of MWCNTs. However, the presence of MWCNTs significantly decreased the yields of each product. These results give insight into the role of MWCNTs in HRP-mediated TBBPA reactions and provide theoretical foundation for potential development of novel enzymatic methods to control TBBPA contamination. MWCNTs enhanced the removal of TBBPA mediated by HRP/H2O2, because it protected HRP from inactivation and adsorbed TBBPA on its surface to form a heterogeneous reaction process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. 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.

  17. 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.

  18. Magneto-resistance of multiwall carbon nanotube Fermat yarn and coil yarn

    NASA Astrophysics Data System (ADS)

    Truong, Kieu; Kang, Haeyong; Lee, Yourack; Kim, Joong-Gyu; Lee, Young Hee; Suh, Dongseok; IBS CenterIntegrated Nanostructure Physics, InstituteBasic Science (IBS), SKKU, Korea Collaboration; Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Korea Collaboration; Department of Physics, Sungkyunkwan University, Suwon 440-746, Korea Collaboration

    2015-03-01

    Multiwall carbon nanotube (MWCNT) based yarn has attracted a great attention for the development of multifunctional super-fiber due to its light weight, high flexibility, high conductivity, and strong mechanical properties (Lima et al. 2011, Science). Recently the importance of coiled yarn structure was demonstrated for practical applications (Haines et al. 2014, Science). In this study, we measured the electrical resistance of neat yarns and coiled yarns at different temperatures and magnetic fields. The coiled yarn was formed by twist-insertion into the neat yarn, and the transverse and longitudinal magnetoresistance (MR) measurements were carried out. The logarithmic temperature dependence of normalized resistance and the negative MR can be explained by the combined contribution of weak-localization effect and the tunneling transport at different temperature ranges. The magnitude difference of MR between two configurations and the survival of such difference even at room temperature indicate that one-dimensional transport features are quite significant in this system. Developing Route for sub-micrometer-scale coil is discussed. This work was supported by Project code (IBS - R011-D1).

  19. Multi-Walled Carbon Nanotube-Doped Tungsten Oxide Thin Films for Hydrogen Gas Sensing

    PubMed Central

    Wongchoosuk, Chatchawal; Wisitsoraat, Anurat; Phokharatkul, Ditsayut; Tuantranont, Adisorn; Kerdcharoen, Teerakiat

    2010-01-01

    In this work we have fabricated hydrogen gas sensors based on undoped and 1 wt% multi-walled carbon nanotube (MWCNT)-doped tungsten oxide (WO3) thin films by means of the powder mixing and electron beam (E-beam) evaporation technique. Hydrogen sensing properties of the thin films have been investigated at different operating temperatures and gas concentrations ranging from 100 ppm to 50,000 ppm. The results indicate that the MWCNT-doped WO3 thin film exhibits high sensitivity and selectivity to hydrogen. Thus, MWCNT doping based on E-beam co-evaporation was shown to be an effective means of preparing hydrogen gas sensors with enhanced sensing and reduced operating temperatures. Creation of nanochannels and formation of p-n heterojunctions were proposed as the sensing mechanism underlying the enhanced hydrogen sensitivity of this hybridized gas sensor. To our best knowledge, this is the first report on a MWCNT-doped WO3 hydrogen sensor prepared by the E-beam method. PMID:22163623

  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. Preparation and Characterization of CdSe-Decorated Multiwalled Carbon Nanotube Composites

    NASA Astrophysics Data System (ADS)

    Kim, Dukeun; Mahbub Rabbani, Mohammad; Ko, Chang Hyun; Nam, Dae-Geun; Yeum, Jeong Hyun; Park, Jong S.; Bae, Jong-Seong; Oh, Weontae

    2011-01-01

    Composites of carboxylated multiwalled carbon nanotubes (c-MWNTs) and CdSe nanoparticles were prepared by the electrostatic interaction. CdSe nanoparticles were stabilized by 2-(dimethylamino)ethanethiol hydrochloride to develop positive charges on their surfaces in aqueous solution. The structural characteristics of these composites were analyzed using X-ray diffraction (XRD), and transmission electron microscopy (TEM). Ultraviolet/visible (UV/vis) spectra of c-MWNT-CdSe composites showed the characteristic bands at ˜250 nm. These results indicate that the energy state of c-MWNTs is significantly modified, which was caused by the homogeneous distribution of CdSe nanoparticles in c-MWNTs, and the bond formation between c-MWNTs and CdSe nanoparticles. The photoluminescence (PL) of CdSe nanoparticles in the composites was characterized in comparison with that of CdSe nanoparticles. PL of CdSe in c-MWNT-CdSe composites was collected at ˜568 nm in solution, but disappeared in powder state.

  2. Synthesis of nickel nanoparticles on multi-walled carbon nanotubes by gamma irradiation

    NASA Astrophysics Data System (ADS)

    Rao, Vivek M.; Castano, Carlos H.; Rojas, Jessika; Abdulghani, Ahlam J.

    2013-08-01

    Multi-walled carbon nanotubes (MWCNTs) were used as a substrate for nickel nanoparticles production. Nickel nanoparticles of average sizes between 9 and 16 nm were synthesized by gamma irradiation of aqueous solutions containing nickel sulfate or nickel chloride as precursors. MWCNTs were acid treated and poly vinyl pyrrolidone (PVP, m˜44,000) or sodium dodecyl sulfate (SDS) were used as stabilizers. Isopropanol was used as a scavenger of hydroxyl radicals, and deionized (DI) water as a solvent. Gamma irradiation was carried out at room temperature and ambient pressure in a 60Co gamma source at doses of 30, 40, 50, and 60 kGy. The nickel nanoparticles were characterized by transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and X-ray photoelectron spectroscopy (XPS). By controlling the dose and stabilizer's concentrations, nanoparticles with different sizes were obtained. Poly vinyl pyrrolidone (PVP) was found to be more efficient at preventing coalescence of Ni seeds than sodium dodecyl sulfate (SDS).

  3. 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.

  4. Morphology and N2 permeability of multi-wall carbon nanotube--Teflon membranes.

    PubMed

    Smajda, Rita; Kukovecz, Akos; Hopp, Béla; Mohl, Melinda; Kónya, Zoltán; Kiricsi, Imre

    2007-01-01

    We prepared buckypapers with surface densities in the 1.13-5.66 mg x cm(-2) range by filtering multi-wall carbon nanotube (MWCNT) suspensions in acetyl-acetone (acac) and dimethylformamide (DMF) through 0.45 microm nylon filters. Filtration curves were evaluated using the Carman equation. The average resistance of the filter itself was found to be Rm = 3.79 x 10(10) m(-1) for acac and 8.49 x 10(10) m(-1) for DMF The specific resistance a of the filter cakes decreased with increasing film surface density from 16.1 x 10(12) m x kg(-1) (for the 1.13 mg x cm(-2) film from DMF) to 4.38 x 10(12) m x kg(-1) (for the 5.66 mg x cm(-2) film from DMF). The effective diffusivity of N2 at 298 K and a pressure difference of 10 mbar was also determined for all membranes and found to fall into the 1.14 x 10(-9)-3.74 x 10(-9) m2 x s(-1) range. Both the porosity and the tortuosity of buckypapers increased with their thickness. An approx. 5 microm thick Teflon (PTFE) coating was applied to the MWCNT membranes by pulsed laser deposition. The gas permeability of the MWCNT-PTFE membranes matches that of the uncoated nanotube films. This observation is an agreement with our SEM and AFM data on porous coating morphology.

  5. Proteomics-based safety evaluation of multi-walled carbon nanotubes

    SciTech Connect

    Haniu, Hisao; Matsuda, Yoshikazu; Takeuchi, Kenji; Kim, Yoong Ahm; Hayashi, Takuya; Endo, Morinobu

    2010-02-01

    This study evaluated the biological responses to multi-walled carbon nanotubes (MWCNTs). Human monoblastic leukemia cells (U937) were exposed to As-grown MWCNTs and MWCNTs that were thermally treated at 1800 deg. C (HTT1800) and 2800 deg. C (HTT2800). Cell proliferation was highly inhibited by As-grown but not HTT2800. However, both As-grown and HTT1800, which include some impurities, were cytotoxic. Proteomics analysis of MWCNT-exposed cells revealed 37 protein spots on 2-dimensional electrophoresis gels that significantly changed (p < 0.05) after exposure to HTT1800 with a little iron and 20 spots that changed after exposure to HTT2800. Peptide mass fingerprinting identified 45 proteins that included heat shock protein beta-1, neutral alpha-glucosidase AB, and DNA mismatch repair protein Msh2. These altered proteins play roles in metabolism, biosynthesis, response to stress, and cell differentiation. Although HTT2800 did not inhibit cell proliferation or cause cytotoxicity in vitro, some proteins related to the response to stress were changed. Moreover, DJ-1 protein, which is a biomarker of Parkinson's disease and is related to cancer, was identified after exposure to both MWCNTs. These results show that the cytotoxicity of MWCNTs depends on their impurities, such as iron, while MWCNTs themselves cause some biological responses directly and/or indirectly in vitro. Our proteomics-based approach for detecting biological responses to nanomaterials is a promising new method for detailed safety evaluations.

  6. Silver nanoparticles/multiwalled carbon nanotube/polyaniline film for amperometric glutathione biosensor.

    PubMed

    Narang, Jagriti; Chauhan, Nidhi; Jain, Preeti; Pundir, C S

    2012-04-01

    A new silver nanoparticles (AgNPs)/carboxylated multiwalled carbon nanotubes (c-MWCNT)/polyaniline (PANI) film has been synthesized on Au electrode using electrochemical techniques. The enzyme glutathione oxidase (GSHOx) (EC 1.8.3.3) was immobilized covalently on the surface of AgNPs/c-MWCNT/PANI/Au electrode to construct the glutathione biosensor. The modified electrode was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared (FTIR) spectrophotometry. The biosensor showed optimum response within 4s at +0.4V vs. Ag/AgCl, pH 6.0 and 35 °C, with a linear working range of 0.3-3500 μM and a detection limit of 0.3 μM. The glutathione biosensor was employed for measurement of glutathione content in hemolysated erythrocyte (RBC). The sensor was evaluated with 97.77% and 99.16% recovery of added glutathione in hemolysated RBC and 2.4% and 6.3% within and between batch coefficients of variation (CVs) respectively. The enzyme electrode lost 50% of its initial activity after 300 uses over a period of 3 months, when stored at 4 °C. The biosensor has the advantages over earlier biosensors in terms of greater stability, lower response time and no interference by a number of RBC hemolysate substances. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Effects of Long and Short Carboxylated or Aminated Multiwalled Carbon Nanotubes on Blood Coagulation

    PubMed Central

    Liu, Jian; Zhang, Weiqi; Li, Xiaojin; Kong, Hua; Xu, Haiyan

    2012-01-01

    In this work the effects of four different multiwalled carbon nanotubes (MWCNTs), including long carboxylated (L-COOH), short carboxylated (S-COOH), long aminated (L-NH2) and short aminated (S-NH2) ones, on the integrity of red blood cells, coagulation kinetics and activation of platelets were investigated with human whole blood. We found that the four MWCNTs induced different degrees of red blood cell damage as well as a mild level of platelet activation (10–25%). L-COOH and L-NH2 induced a higher level of platelet activation than S-COOH and S-NH2 respectively; meanwhile L-NH2 caused marked reductions in platelet viability. The presence of the four MWCNTs led to earlier fibrin formation, L-NH2 increased the clots hardness significantly, while L-COOH and S-NH2 made the clots become softer. It was concluded that the four MWCNTs affected blood coagulation process and the clots mechanical properties; they also altered the integrity of the red blood cells and the viability of the platelets, as well as induced platelets activation. The effects of MWCNTs depended on the size and chemistry of the nanotubes and the type of cells they contacted. PMID:22808023

  8. Chelerythrine and Fe3O4 Loaded Multi-Walled Carbon Nanotubes for Targeted Cancer Therapy.

    PubMed

    Cao, Liangli; Liang, Yongbo; Zhao, Feijun; Zhao, Xiongjie; Chen, Zhencheng

    2016-06-01

    The work focused on manufacturing improved drug loaded multifunctional magnetic nanoparticles that can overcome the relative non-specificity and potential side-effects of some chemotherapeutic drugs to healthy tissues. A new drug delivery system, Chelerythrine (CHE) and Fe3O4 loaded multi-walled carbon nanotubes (Fe3O4/MWNTs-CHE nanocomposites) that can target hepatocytes when treating malignant tumors, was prepared through a simple adsorption method. The formulation and structure of the Fe3O4/MWNTs-CHE nanocomposites were characterized by vibrating sample magnetometer (VSM), Fourier Transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The cytotoxicity and anti-proliferation effect from the prepared nanocomposites were in vitro tested on human hepatocarcinoma HepG2 and normal liver LO2 cell lines. The results showed the saturated magnetization of Fe3O4/MWNTs-CHE nanocomposites could reach to 45.4O3 emu/g, and the in vitro CHE release behavior exhibited a biphasic release pattern. Moreover, the in vitro cytotoxicity studies revealed that the Fe3O4/MWNTs-CHE nanocomposites showed an efficient inhibition rate to HepG2 cell line and exhibited a lower cytotoxicity to LO2 cell line in comparison to the native CHE. Therefore, the multifunctional Fe3O4/MWNTs-CHE nanocomposites should be a useful and promising candidate for treatment of malignant tumors.

  9. Ubiquitous Low-Cost Functionalized Multi-Walled Carbon Nanotube Sensors for Distributed Methane Leak Detection

    SciTech Connect

    Humayun, Md Tanim; Divan, Ralu; Stan, Liliana; Rosenmann, Daniel; Gosztola, David; Gundel, Lara; Solomon, Paul A.; Paprotny, Igor

    2016-06-16

    This paper presents a highly sensitive, energy efficient and low-cost distributed methane (CH4) sensor system (DMSS) for continuous monitoring, detection, and localization of CH4 leaks in natural gas infrastructure, such as transmission and distribution pipelines, wells, and production pads. The CH4 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 CH4. A Gaussian plume triangulation algorithm has been developed for the DMSS. Given a geometric model of the surrounding environment the algorithm can precisely detect and localize a CH4 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.

  10. Carcinogenicity of multi-walled carbon nanotubes: challenging issue on hazard assessment

    PubMed Central

    Fukushima, Shoji; Kasai, Tatsuya; Umeda, Yumi; Ohnishi, Makoto; Sasaki, Toshiaki; Matsumoto, Michiharu

    2017-01-01

    Objectives: This report reviews the carcinogenicity of multi-walled carbon nanotubes (MWCNTs) in experimental animals, concentrating on MWNT-7, a straight fibrous MWCNT. Methods: MWCNTs were administered to mice and rats by intraperitoneal injection, intrascrotal injection, subcutaneous injection, intratracheal instillation and inhalation. Results: 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. Conclusions: 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/m3 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. PMID:29046510

  11. Responses of testis, epididymis, and sperm of pubertal rats exposed to functionalized multiwalled carbon nanotubes.

    PubMed

    Farombi, Ebenezer O; Adedara, Isaac A; Forcados, Gilead E; Anao, Osemudiamen O; Agbowo, Agatha; Patlolla, Anita K

    2016-05-01

    The present study investigated the response of testes, epididymides and sperm in pubertal Wistar rats following exposure to 0, 0.25, 0.5, 0.75, and 1.0 mg kg(-1) functionalized multi-walled carbon nanotubes (f-MWCNTs) for 5 days. The results showed that administration of (f-MWCNTs) significantly increased the activities of superoxide dismutase, catalase, and glutathione peroxidase in a dose-dependent manner in both testes and sperm compared with control group. Moreover, the significant decrease in the activity of glutathione-S-transferase and glutathione level was accompanied with significant elevation in the levels of hydrogen peroxide and malondialdehyde in both testes and sperm of (f-MWCNTs)-treated rats. The spermiogram of (f-MWCNTs)-treated rats indicated significant decrease in epididymal sperm number, sperm progressive motility, testicular sperm number and daily sperm production with elevated sperm abnormalities when compared with the control. Exposure to (f-MWCNTs) decreased plasma testosterone level and produced marked morphological changes including decreased geminal epithelium, edema, congestion, reduced spermatogenic cells and focal areas of tubular degeneration in the testes. The lumen of the epididymides contained reduced sperm cells and there was mild to severe hyperplasia epithelial cells lining the duct of the epididymis. Collectively, pubertal exposure of male rats to (f-MWCNTs) elicited oxidative stress response resulting in marked testicular and epididymides dysfunction. © 2014 Wiley Periodicals, Inc.

  12. Field Electron Emission Devices with Oriented Carbon Nanotubes Dispersed in Aluminum Composites

    NASA Astrophysics Data System (ADS)

    Tsuruno, Yusuke; Nakanishi, Yusuke; Yanagi, Hisao; Takizawa, Katsuo; Horikawa, Yuichi; Yokoyama, Kazuyuki; Magario, Akira; Noguchi, Toru

    2010-08-01

    Multiwalled carbon nanotubes (MWNTs) were homogeneously dispersed into aluminum (Al) powder by the elastomer precursor method. MWNT/Al composites were prepared by extrusion molding of the precursor powder and cut into thin plates. Each composite plate was split parallel or perpendicular to the extrusion direction, and used for field emission measurements. The perpendicular cross section exhibited excellent electron emission with a threshold electric field of 2.0 V/µm and a current density of 1.5 mA/cm2 since a considerable number of oriented MWNTs were sticking out of the cross-sectional surface. With those oriented MWNT/Al composite emitters, a flat-panel field emission lamp (FEL) was successfully fabricated by using the side-electron emission device (SEED) structure.

  13. Multi-walled carbon nanotubes with immobilised cobalt nanoparticle for modification of glassy carbon electrode: application to sensitive voltammetric determination of thioridazine.

    PubMed

    Shahrokhian, Saeed; Ghalkhani, Masoumeh; Adeli, Mohsen; Amini, Mohammad Kazem

    2009-07-15

    Multi-walled carbon nanotubes (MWCNTs) were immobilised with cobalt nanoparticles and analyzed by transmission electron microscopy. This modification procedure substantially improved colloidal dispersion of the immobilised MWCNTs in water and organic solvents, yielding uniform and stable thin films for modification of the glassy carbon electrode surface. The modified electrode showed an efficient catalytic role for the electrochemical oxidation of thioridazine (TR), leading to remarkable decrease in its oxidation overpotential of approximately 100 mV and enhancement of the kinetics of the electrode reaction, which can be confirmed by increasing in the peak current and sharpness of the peak. A remarkable enhancement in microscopic area of the electrode together with the catalytic role of the composite modifier resulted in a considerable increase of the peak current (approximately 55 times), and negative shift in the oxidation potential of TR. The effect of the thickness of the modifier on the GCE surface was optimized by monitoring its cyclic voltammetric responses toward TR. The mechanism of the electrocatalytic process on the surface of the modified electrode was analyzed by obtaining the cyclic voltammograms at various potential sweep rates and pHs of the buffer solutions. Differential pulse voltammetry was applied as a very sensitive analytical method for the determination of sub-micromolar amounts of TR. A linear dynamic range of 5.0 x 10(-7) to 1.0 x 10(-4)M with a detection limit of 5.0 x 10(-8)M TR was obtained. The prepared modified electrode shows several advantages such as simple preparation method, high stability and uniformity in the composite film, high sensitivity, and excellent catalytic activity in physiological conditions, long-term stability and remarkable voltammetric reproducibility. These excellent properties make the prepared sensor suitable for analysis in pharmaceutical and clinical preparations. The modified electrode was successfully

  14. Voltammetric determination of antibacterial drug gemifloxacin in solubilized systems at multi-walled carbon nanotubes modified glassy carbon electrode.

    PubMed

    Jain, Rajeev; Rather, Jahangir Ahmad

    2011-04-01

    A sensitive electroanalytical method for determination of gemifloxacin in pharmaceutical formulation has been investigated on the basis of the enhanced electrochemical response at multi-walled carbon nanotubes modified glassy carbon electrode in the presence of CTAB. Solubilized system of different surfactants including SDS, Tween-20 and CTAB were taken for the study of electrochemical behaviour of gemifloxacin at modified electrode. The reduction peak current increases in the presence of CTAB while other surfactants show opposite effect. The modified electrode exhibits catalytic activity, high sensitivity, stability and is applicable over wide range of concentration for the determination of gemifloxacin. The mechanism of electrochemical reduction of gemifloxacin has been proposed on the basis of CV, SWV, DPV and coulometeric techniques. The proposed squarewave voltammetric method shows linearity over the concentration range 2.47-15.5 μg/mL. The achieved limits of detection (LOD) and quantification (LOQ) are 0.90 ng/mL and 3.0 ng/mL respectively. Crown Copyright © 2010. Published by Elsevier B.V. All rights reserved.

  15. Determination of oleuropein using multiwalled carbon nanotube modified glassy carbon electrode by adsorptive stripping square wave voltammetry.

    PubMed

    Cittan, Mustafa; Koçak, Süleyman; Çelik, Ali; Dost, Kenan

    2016-10-01

    A multi-walled carbon nanotube modified glassy carbon electrode was used to prepare an electrochemical sensing platform for the determination of oleuropein. Results showed that, the accumulation of oleuropein on the prepared electrode takes place with the adsorption process. Electrochemical behavior of oleuropein was studied by using cyclic voltammetry. Compared to the bare GCE, the oxidation peak current of oleuropein increased about 340 times at MWCNT/GCE. Voltammetric determination of oleuropein on the surface of prepared electrode was studied using square wave voltammetry where the oxidation peak current of oleuropein was measured as an analytical signal. A calibration curve of oleuropein was performed between 0.01 and 0.70µM and a good linearity was obtained with a correlation coefficient of 0.9984. Detection and quantification limits of the method were obtained as 2.73 and 9.09nM, respectively. In addition, intra-day and inter-day precision studies indicated that the voltammetric method was sufficiently repeatable. Finally, the proposed electrochemical sensor was successfully applied to the determination of oleuropein in an olive leaf extract. Microwave-assisted extraction of oleuropein had good recovery values between 92% and 98%. The results obtained with the proposed electrochemical sensor were compared with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Fe-N-modified multi-walled carbon nanotubes for oxygen reduction reaction in acid.

    PubMed

    Byon, Hye Ryung; Suntivich, Jin; Crumlin, Ethan J; Shao-Horn, Yang

    2011-12-28

    We report a facile synthesis of Fe-N-C catalysts based on the surface functionalization of multi-walled carbon nanotubes (MWCNTs), which show high activity and stability for oxygen reduction reaction (ORR) in acid. Fe-N-MWCNT catalysts, whose ORR mass activities could vary by 3-4 times depending on the choice of Fe precursors, were found to have considerably higher ORR mass activity and higher stability than N-modified MWCNTs (N-MWCNTs). The Fe-N-MWCNT catalyst with a dominant Fe-N(x) moiety (with x ≈ 4) and a surface Fe/C ratio of ∼0.004 exhibits the highest ORR mass activity in acid (∼0.7 mA mg(-1)(Fe-N-MWCNT) at 0.8 V vs. RHE), where the lower mass activity of other Fe-N-MWCNT catalysts can be attributed to lower Fe/C ratios and Fe-N(x) moieties (with x smaller than 4) as revealed from X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) spectroscopy. Moreover, the enhanced stability of Fe-N-MWCNTs in comparison to N-MWCNTs can be attributed to less H(2)O(2) production during ORR as determined from rotating ring disk electrode (RRDE) measurements, and higher activity for H(2)O(2) electro-reduction by rotating disk electrode (RDE) measurements. The large surface Fe/C ratio and Fe-N(x) moiety corresponding to high ORR activity and stability of Fe-N-MWCNTs demonstrate that surface functionalization can be very helpful to graft active catalytic sites onto carbon nanostructures, and to provide insights into the ORR mechanism of non-noble metal catalysts (NNMCs) for proton exchange membrane fuel cells (PEMFCs).

  17. Inhaled Multiwalled Carbon Nanotubes Potentiate Airway Fibrosis in Murine Allergic Asthma

    PubMed Central

    Ryman-Rasmussen, Jessica P.; Tewksbury, Earl W.; Moss, Owen R.; Cesta, Mark F.; Wong, Brian A.; Bonner, James C.

    2009-01-01

    Carbon nanotubes are gaining increasing attention due to possible health risks from occupational or environmental exposures. This study tested the hypothesis that inhaled multiwalled carbon nanotubes (MWCNT) would increase airway fibrosis in mice with allergic asthma. Normal and ovalbumin-sensitized mice were exposed to a MWCNT aerosol (100 mg/m3) or saline aerosol for 6 hours. Lung injury, inflammation, and fibrosis were examined by histopathology, clinical chemistry, ELISA, or RT-PCR for cytokines/chemokines, growth factors, and collagen at 1 and 14 days after inhalation. Inhaled MWCNT were distributed throughout the lung and found in macrophages by light microscopy, but were also evident in epithelial cells by electron microscopy. Quantitative morphometry showed significant airway fibrosis at 14 days in mice that received a combination of ovalbumin and MWCNT, but not in mice that received ovalbumin or MWCNT only. Ovalbumin-sensitized mice that did not inhale MWCNT had elevated levels IL-13 and transforming growth factor (TGF)-β1 in lung lavage fluid, but not platelet-derived growth factor (PDGF)-AA. In contrast, unsensitized mice that inhaled MWCNT had elevated PDGF-AA, but not increased levels of TGF-β1 and IL-13. This suggested that airway fibrosis resulting from combined ovalbumin sensitization and MWCNT inhalation requires PDGF, a potent fibroblast mitogen, and TGF-β1, which stimulates collagen production. Combined ovalbumin sensitization and MWCNT inhalation also synergistically increased IL-5 mRNA levels, which could further contribute to airway fibrosis. These data indicate that inhaled MWCNT require pre-existing inflammation to cause airway fibrosis. Our findings suggest that individuals with pre-existing allergic inflammation may be susceptible to airway fibrosis from inhaled MWCNT. PMID:18787175

  18. 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.

    2017-11-01

    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.

  19. 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%.

  20. Nicotinamide-functionalized multiwalled carbon nanotubes increase insulin production in pancreatic beta cells via MIF pathway.

    PubMed

    Ilie, Ioana; Ilie, Razvan; Mocan, Teodora; Tabaran, Flaviu; Iancu, Cornel; Mocan, Lucian

    2013-01-01

    Recent data in the literature support the role of nicotinamide (NA) as a pharmacologic agent that stimulates pancreatic beta-cells to produce insulin in vitro. There are data showing that carbon nanotubes may be useful in initiating and maintaining cellular metabolic responses. This study shows that administration of multiwalled carbon nanotubes (MWCNTs) functionalized with nicotinamide (NA-MWCNTs) leads to significant insulin production compared with individual administration of NA, MWCNTs, and a control solution. Treatment of 1.4E7 cells for 30 minutes with NA-MWCNTs at concentrations ranging from 1 mg/L to 20 mg/L resulted in significantly increased insulin release (0.18 ± 0.026 ng/mL for 1 mg/L, 0.21 ± 0.024 ng/mL for 5 mg/L, and 0.27 ± 0.028 ng/mL for 20 mg/L). Thus, compared with cells treated with NA only (0.1 ± 0.01 ng/mL for 1 mg/L, 0.12 ± 0.017 ng/mL for 5 mg/L, and 0.17 ± 0.01 ng/mL for 20 mg/L) we observed a significant positive effect on insulin release in cells treated with NA-MWCNTs. The results were confirmed using flow cytometry, epifluorescence microscopy combined with immunochemistry staining, and enzyme-linked immunosorbent assay techniques. In addition, using immunofluorescence microscopy techniques, we were able to demonstrate that MWCNTs enhance insulin production via the macrophage migration inhibitory factor pathway. The application and potential of NA combined with MWCNTs as an antidiabetic agent may represent the beginning of a new chapter in the nanomediated treatment of diabetes mellitus.

  1. Occupational Exposure to Multi-Walled Carbon Nanotubes During Commercial Production Synthesis and Handling.

    PubMed

    Kuijpers, Eelco; Bekker, Cindy; Fransman, Wouter; Brouwer, Derk; Tromp, Peter; Vlaanderen, Jelle; Godderis, Lode; Hoet, Peter; Lan, Qing; Silverman, Debra; Vermeulen, Roel; Pronk, Anjoeka

    2016-04-01

    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 200 nm 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. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  2. 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.

  3. 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.

  4. An ultrasensitive multi-walled carbon nanotube-platinum-luminol nanocomposite-based electrochemiluminescence immunosensor.

    PubMed

    Zhang, Xin; Ke, Hong; Wang, Zhiming; Guo, Weiwei; Zhang, Amin; Huang, Chusen; Jia, Nengqin

    2017-06-12

    An ultrasensitive electrochemiluminescence (ECL) immunosensor for carbohydrate antigen 19-9 (CA19-9) detection using multi-walled carbon nanotube-platinum-luminol nanocomposites (MWCNT-Pt-luminol) as nanointerface and signal tags was designed. First, the MWCNT-Pt-luminol nanocomposite was decorated on the surface of a glassy carbon electrode (GCE) through the film-forming properties of chitosan (Chi). Then, the CA19-9 antibody (anti-CA19-9) was attached to the modified electrode surface via crosslinking with glutaraldehyde (GA). When CA19-9 was captured by its antibody immobilized on the immune platform via immunoreaction, the ECL signal intensity decreased. Under optimal conditions, the proposed ECL immunosensor showed excellent performance for CA19-9 ranging from 0.0001 U mL-1 to 10.0 U mL-1, with a detection limit of 0.000046 U mL-1 (S/N = 3) and a correlation coefficient of R = 0.9980. This is attributed to the fact that the MWCNTs-Pt nanomaterial has excellent conductivity and it could facilitate the decomposition of H2O2 to generate various reactive oxygen species (ROSs); thus, the ECL signals of luminol were effectively amplified and the sensitivity of the sensor was greatly increased. The prepared ECL immunosensor displayed simple, fast analysis, excellent stability, good reproducibility, and high specificity. Moreover, the developed ECL immunosensor provided satisfactory results in the determination of CA19-9 in real human serum samples.

  5. 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.

  6. Photothermal therapy of glioblastoma multiforme using multiwalled carbon nanotubes optimized for diffusion in extracellular space.

    PubMed

    Eldridge, Brittany N; Bernish, Brian W; Fahrenholtz, Cale D; Singh, Ravi

    2016-06-13

    Glioblastoma multiforme (GBM) is the most common and most lethal primary brain tumor with a 5 year overall survival rate of approximately 5%. Currently, no therapy is curative and all have significant side effects. Focal thermal ablative therapies are being investigated as a new therapeutic approach. Such therapies can be enhanced using nanotechnology. Carbon nanotube mediated thermal therapy (CNMTT) uses lasers that emit near infrared radiation to excite carbon nanotubes (CNTs) localized to the tumor to generate heat needed for thermal ablation. Clinical translation of CNMTT for GBM will require development of effective strategies to deliver CNTs to tumors, clear structure-activity and structure-toxicity evaluation, and an understanding of the effects of inherent and acquired thermotolerance on the efficacy of treatment. In our studies, we show that a dense coating of phospholipid-poly(ethylene glycol) on multiwalled CNTs (MWCNTS) allows for better diffusion through brain phantoms, while maintaining the ability to achieve ablative temperatures after laser exposure. Phospholipid-poly(ethylene glycol) coated MWCNTs do not induce a heat shock response (HSR) in GBM cell lines. Activation of the HSR in GBM cells via exposure to sub-ablative temperatures or short term treatment with an inhibitor of heat shock protein 90 (17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17-DMAG)), induces a protective heat shock response that results in thermotolerance and protects against CNMTT. Finally, we evaluate the potential for CNMTT to treat GBM multicellular spheroids. These data provide pre-clinical insight into key parameters needed for translation of CNMTT including nanoparticle delivery, cytotoxicity, and efficacy for treatment of thermotolerant GBM.

  7. Glassy carbon electrodes modified with multiwalled carbon nanotubes for the determination of ascorbic acid by square-wave voltammetry.

    PubMed

    Kumar, Sushil; Vicente-Beckett, Victoria

    2012-01-01

    Multiwalled carbon nanotubes were used to modify the surface of a glassy carbon electrode to enhance its electroactivity. Nafion served to immobilise the carbon nanotubes on the electrode surface. The modified electrode was used to develop an analytical method for the analysis of ascorbic acid (AA) by square-wave voltammetry (SWV). The oxidation of ascorbic acid at the modified glassy carbon electrode showed a peak potential at 315 mV, about 80 mV lower than that observed at the bare (unmodified) electrode. The peak current was about threefold higher than the response at the bare electrode. Replicate measurements of peak currents showed good precision (3% rsd). Peak currents increased with increasing ascorbic acid concentration (dynamic range = 0.0047-5.0 mmol/L) and displayed good linearity (R(2) = 0.994). The limit of detection was 1.4 μmol/L AA, while the limit of quantitation was 4.7 μmol/L AA. The modified electrode was applied to the determination of the amount of ascorbic acid in four brands of commercial orange-juice products. The measured content agreed well (96-104%) with the product label claim for all brands tested. Recovery tests on spiked samples of orange juice showed good recovery (99-104%). The reliability of the SWV method was validated by conducting parallel experiments based on high-performance liquid chromatography (HPLC) with absorbance detection. The observed mean AA contents of the commercial orange juice samples obtained by the two methods were compared statistically and were found to have no significant difference (P = 0.05).

  8. 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.

  9. 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.

  10. 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.

  11. The influence of inhaled multi-walled carbon nanotubes on the autonomic nervous system.

    PubMed

    Zheng, W; McKinney, W; Kashon, M; Salmen, R; Castranova, V; Kan, H

    2016-02-11

    Heart rate and cardiovascular function are regulated by the autonomic nervous system. Heart rate variability (HRV) as a marker reflects the activity of autonomic nervous system. The prognostic significance of HRV in cardiovascular disease has been reported in clinical and epidemiological studies. The present study focused on the influence of inhaled multi-walled carbon nanotubes (MWCNTs) on autonomic nervous system by HRV analysis. Male Sprague-Dawley rats were pre-implanted with a telemetry device and kept in the individual cages for recovery. At week four after device implantation, rats were exposed to MWCNTs for 5 h at a concentration of 5 mg/m(3). The real-time EKGs were recorded by a telemetry system at pre-exposure, during exposure, 1 day and 7 days post-exposure. HRV was measured by root mean square of successive differences (RMSSD); the standard deviation of inter-beat (RR) interval (SDNN); the percentage of successive RR interval differences greater than 5 ms (pNN5) and 10 ms (pNN10); low frequency (LF) and high frequency (HF). Exposure to MWCNTs increased the percentage of differences between adjacent R-R intervals over 10 ms (pNN10) (p < 0.01), RMSSD (p < 0.01), LF (p < 0.05) and HF (p < 0.01). Inhalation of MWCNTs significantly alters the balance between sympathetic and parasympathetic nervous system. Whether such transient alterations in autonomic nervous performance would alter cardiovascular function and raise the risk of cardiovascular events in people with pre-existing cardiovascular conditions warrants further study.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  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. 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

  15. 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.

  16. Toxicity determinants of multi-walled carbon nanotubes: The relationship between functionalization and agglomeration.

    PubMed

    Allegri, Manfredi; Perivoliotis, Dimitrios K; Bianchi, Massimiliano G; Chiu, Martina; Pagliaro, Alessandra; Koklioti, Malamatenia A; Trompeta, Aikaterini-Flora A; Bergamaschi, Enrico; Bussolati, Ovidio; Charitidis, Constantinos A

    2016-01-01

    The elucidation of toxicity determinants of multi-walled carbon nanotubes (MWCNT) is still incomplete. Functionalization with carboxyl groups is, however, commonly used to mitigate MWCNT toxicity, although the rationale for the mitigating effect has not been fully clarified yet. In this work, two optimized chemical vapor deposition methods were employed to obtain MWCNT of comparable length but different diameter, which were subsequently functionalized. For MWCNT of diameter larger than 40 nm, no detrimental effects on cell viability of macrophages were observed, while mild cytotoxicity was recorded for diameters between 15 and 40 nm, with a mitigating effect of functionalization. To investigate the factors responsible for the mitigation, we used the thinnest MWCNT preparation on different cell models, evaluating several endpoints, such as viability, production of nitric oxide (NO), expression of pro-inflammatory markers, the Trans-Epithelial Electrical Resistance (TEER), and clonogenic activity. Substantial mitigation of the changes caused by pristine MWCNT was observed not only with carboxyl- but also with amino-functionalized MWCNT, suggesting that negative or positive surface charge was not the main factor responsible for the effect. Instead, either functionalized preparation exhibited a stronger tendency to agglomerate that was strictly dependent on the presence of proteins. Moreover, we found that either carboxyl- or amino-functionalized MWCNT adsorbed a larger amount of serum proteins than pristine counterparts, with a distinctive pattern for each type of MWCNT. We propose, therefore, that the formation of larger agglomerates, dependent upon different protein coronae, contributes to mitigate the biological effects of functionalized MWCNT in protein-rich biological media.

  17. 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

  18. Distribution and persistence of pleural penetrations by multi-walled carbon nanotubes

    PubMed Central

    2010-01-01

    Background Multi-walled carbon nanotubes (MWCNT) are new manufactured nanomaterials with a wide spectrum of commercial applications. The durability and fiber-like dimensions (mean length 3.9 μm long × 49 nm diameter) of MWCNT suggest that these fibers may migrate to and have toxicity within the pleural region. To address whether the pleura received a significant and persistent exposure, C57BL/6J mice were exposed by pharyngeal aspiration to 10, 20, 40 and 80 μg MWCNT or vehicle and the distribution of MWCNT penetrations determined at 1, 7, 28 and 56 days after exposure. Following lung fixation and sectioning, morphometric methods were used to determine the distribution of MWCNT and the number of MWCNT fiber penetrations of three barriers: alveolar epithelium (alveolar penetrations), the alveolar epithelium immediately adjacent to the pleura (subpleural tissue), and visceral pleural surface (intrapleural space). Results At 1 day 18%, 81.6% and 0.6% of the MWCNT lung burden was in the airway, the alveolar, and the subpleural regions, respectively. There was an initial, high density of penetrations into the subpleural tissue and the intrapleural space one day following aspiration which appeared to decrease due to clearance by alveolar macrophages and/or lymphatics by day 7. However, the density of penetrations increased to steady state levels in the subpleural tissue and intrapleural from day 28 - 56. At day 56 approximately 1 in every 400 fiber penetrations was in either the subpleural tissue or intrapleural space. Numerous penetrations into macrophages in the alveolar airspaces throughout the lungs were demonstrated at all times but are not included in the counts presented. Conclusions The results document that MWCNT penetrations of alveolar macrophages, the alveolar wall, and visceral pleura are both frequent and sustained. In addition, the findings demonstrate the need to investigate the chronic toxicity of MWCNT at these sites. PMID:20920331

  19. Multi-walled carbon nanotube physicochemical properties predict pulmonary inflammation and genotoxicity

    PubMed Central

    Poulsen, Sarah S.; Jackson, Petra; Kling, Kirsten; Knudsen, Kristina B.; Skaug, Vidar; Kyjovska, Zdenka O.; Thomsen, Birthe L.; Clausen, Per Axel; Atluri, Rambabu; Berthing, Trine; Bengtson, Stefan; Wolff, Henrik; Jensen, Keld A.; Wallin, Håkan; Vogel, Ulla

    2016-01-01

    Abstract Lung deposition of multi-walled carbon nanotubes (MWCNT) induces pulmonary toxicity. Commercial MWCNT vary greatly in physicochemical properties and consequently in biological effects. To identify determinants of MWCNT-induced toxicity, we analyzed the effects of pulmonary exposure to 10 commercial MWCNT (supplied in three groups of different dimensions, with one pristine and two/three surface modified in each group). We characterized morphology, chemical composition, surface area and functionalization levels. MWCNT were deposited in lungs of female C57BL/6J mice by intratracheal instillation of 0, 6, 18 or 54 μg/mouse. Pulmonary inflammation (neutrophil influx in bronchoalveolar lavage (BAL)) and genotoxicity were determined on day 1, 28 or 92. Histopathology of the lungs was performed on day 28 and 92. All MWCNT induced similar histological changes. Lymphocytic aggregates were detected for all MWCNT on day 28 and 92. Using adjusted, multiple regression analyses, inflammation and genotoxicity were related to dose, time and physicochemical properties. The specific surface area (BET) was identified as a positive predictor of pulmonary inflammation on all post-exposure days. In addition, length significantly predicted pulmonary inflammation, whereas surface oxidation (–OH and –COOH) was predictor of lowered inflammation on day 28. BET surface area, and therefore diameter, significantly predicted genotoxicity in BAL fluid cells and lung tissue such that lower BET surface area or correspondingly larger diameter was associated with increased genotoxicity. This study provides information on possible toxicity-driving physicochemical properties of MWCNT. The results may contribute to safe-by-design manufacturing of MWCNT, thereby minimizing adverse effects. PMID:27323647

  20. Properties of a weakly ionized NO gas sensor based on multi-walled carbon nanotubes

    SciTech Connect

    Zhang, Jingyuan; Zhang, Yong Pan, Zhigang; Yang, Shuang; Shi, Jinghui; Li, Shengtao; Min, Daomin; Wang, Xiaohua; Liu, Dingxin; Yang, Aijun; Li, Xin

    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 concentration 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}.

  1. Ni-coated multi-walled carbon nanotubes enhanced the magnetorheological performance of magnetorheological gel

    NASA Astrophysics Data System (ADS)

    Yang, Pingan; Yu, Miao; Fu, Jie

    2016-03-01

    As a kind of new Magnetorheological (MR) material, MR Gel (MRG) can be regarded as the analog of MR fluid (MRF), which can overcome the iron particles sedimentation and unstable application of MRF. Normally, the storage modulus of conventional MRG is relatively small, although it has a very high relative MR effect. Therefore, practical engineering application of conventional MRG has been restricted more or less. In this work, an MRG with high magneto-induced shear storage modulus and excellent relative MR effect has been fabricated by incorporating Ni-coated multi-walled carbon nanotubes (Ni-coated MWCNTs). And several polyurethane-based MRG composites with the addition of Ni-coated MWCNTs were prepared. The dynamic mechanical property of those MRG composites with applying magnetic field is researched through an advanced commercial rheometer. The experimental results indicated that the initial storage modulus and magneto-induced modulus in sample 4 (containing 6 wt% of the Ni-coated MWCNTs) were approximately 4.45 and 2.27 times than that in the sample 1 (without Ni-coated MWCNTs). Moreover, the relative MR effect of sample 4 can reach 3427 %. The high modulus of sample 4 can be mainly attributed to the following points. One is the Ni-coated MWCNTs can be aligned along the direction of the magnetic field within the matrix which provided a better reinforcing efficiency. The other is Ni-coated MWCNTs can be made to form a better bonding between the iron particles and the matrix. It is concluded that this study provides a meaningful way to improve the mechanical properties of MRG and expected to promote the application of MRG in practice.

  2. 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

  3. Electrochemical efficacy of a carboxylated multiwalled carbon nanotube filter for the removal of ibuprofen from aqueous solutions under acidic conditions.

    PubMed

    Bakr, Ahmed Refaat; Rahaman, Md Saifur

    2016-06-01

    This study provides insight into the efficiency of a functionalized multiwalled carbon nanotube filter for the removal of an anti-inflammatory drug, ibuprofen, through conventional filtration and electrochemical filtration processes. A comparison was made between carboxylated multiwalled carbon nanotubes (MWNTs-COOH) and pristine multiwalled carbon nanotubes (MWNTs) in order to emphasize the enhanced performance of MWNTs-COOH for the removal of ibuprofen using an electrochemical filtration process under acidic conditions. Ibuprofen-removal trials were evaluated based on absorbance values obtained using a UV/Vis spectrophotometer, and possible degradation products were identified using liquid chromatography mass spectrometry (LC-MS). The results exhibited near complete removal of ibuprofen by MWNTs-COOH at lower applied potentials (2 V), at lower flow rates, and under acidic conditions, which can be attributed to the generation of superoxides and their active participation in simultaneous degradation of ibuprofen, and its by-products, under these conditions. At higher applied potential (3 V), the possible participation of both bulk indirect oxidation reactions, and direct electron transfer were hypothesized for the removal behavior over time (breakthrough). At 3 V under acidic conditions, near 100% removal of the target molecule was achieved and was attributed to the enhanced generation of electroactive species toward bulk chemical reactions and a possible contribution from direct electron transfer under these conditions. The degradation by-products of ibuprofen were effectively removed by allowing longer residence time during the filtration process. Moreover, the effect of temperature was studied, yet showed a non-significant effect on the overall removal process. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Synthesis of zinc oxide particles coated multiwalled carbon nanotubes: Dielectric properties, electromagnetic interference shielding and microwave absorption

    SciTech Connect

    Song, Wei-Li; Cao, Mao-Sheng; Wen, Bo; Hou, Zhi-Ling; Cheng, Jin; Yuan, Jie

    2012-07-15

    Graphical abstract: A resistor–capacitor model could well describe the relationships between the structure and the dielectric properties, electromagnetic interference shielding and microwave-absorption of the composites in the frequency range of 2–18 GHz. The resonant behavior associated with the multiwalled carbon nanotubes/zinc oxide (MWCNTs/ZnO) interface greatly broadens the absorption band. Highlights: ► ZnO-immobilized on multiwalled carbon nanotubes (MWCNTs/ZnO) have resonant behavior. ► A resistor–capacitor model describes the relation between the structure and properties. ► The composite with 40 wt% MWCNTs/ZnO has good electromagnetic interference shielding. ► Two different types of absorption peaks are found in the MWCNTs/ZnO composites. ► The existence of MWCNTs/ZnO interface broadens the absorption band. -- Abstract: Zinc oxide (ZnO) nanoparticles were coated on the surfaces of multiwalled carbon nanotubes (MWCNTs). High resolution transmission electron microscopy images show that the wurtzite ZnO immobilized on the MWCNTs is single-crystalline with a preferential [0 0 0 2] growth direction. A capacitor was generated by the interface of ZnO and MWCNTs, and a resistor–capacitor model could well describe the relationships between the structure and the dielectric properties, electromagnetic interference shielding and microwave-absorption of the composites in the frequency range of 2–18 GHz. The network built by ZnO-immobilized MWCNTs could contribute to the improvement of electrical properties. Resonant peaks associated with the capacitor formed by the interface were observed in the microwave absorption spectra, which suggest that reflection–loss peaks greatly broadens the absorption bandwidth.

  5. 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.

  6. 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.

  7. 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 \

  8. Optical limiting response of multi-walled carbon nanotube-phthalocyanine nanocomposite in solution and when in poly (acrylic acid)

    NASA Astrophysics Data System (ADS)

    Sekhosana, Kutloano Edward; Nyokong, Tebello

    2016-08-01

    Bis{23-(3,4-di-yloxybenzoic acid)-(2(3), 9(10), 16(17), 23(24)-(hexakis-pyridin-3-yloxy phthalocyaninato)} dineodymium (III) acetate (3) is linked to amino-functionalized multi-walled carbon nanotubes (MWCNT) to form 3-MWCNT. Z-scan technique was employed to experimentally determine the nonlinear absorption coefficient from the open-aperture data. The limiting threshold values as low as 0.045 J cm-2 were found in solution. The conjugate (3-MWCNT) gave better optical limiting behavior than complex 3 alone.

  9. 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

  10. 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.

    2016-04-15

    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

  11. Immobilization of ruthenium phthalocyanine on silica-coated multi-wall partially oriented carbon nanotubes: Electrochemical detection of fenitrothion pesticide

    SciTech Connect

    Canevari, Thiago C.; Prado, Thiago M.; Cincotto, Fernando H.; Machado, Sergio A.S.

    2016-04-15

    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 presence 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.

  12. Lack of mutagenic effect by multi-walled functionalized carbon nanotubes in the somatic cells of Drosophila melanogaster.

    PubMed

    Machado, N M; Lopes, J C; Saturnino, R S; Fagan, E B; Nepomuceno, J C

    2013-12-01

    Carbon nanotubes (CNTs) are formed by rolling up a single graphite sheet into a tube. Among the different types of CNTs, the multi-walled carbon nanotubes (MWCNTs) comprise a set of concentric nanotubes with perfect structures. Several uses for MWCNTs have been suggested to be included in biological applications such as manufacturing of biosensors, carriers of drugs. However, before these materials can be put on the market, it is necessary to know their genotoxic effects. Thus, this study aims to evaluate the mutagenicity of multi-walled carbon nanotubes (MWCNTs) functionalized in somatic cells of Drosophila melanogaster, using the somatic mutation and recombination test (SMART). This assay detects the loss of heterozygosity of marker genes expressed phenotypically on the wings of the fly. Larvae of three days were used, resulting from ST cross, with basal levels of the cytochrome P450 and larvae of high metabolic bioactivity capacity (HB cross). They were treated with different concentrations of MWCNTs functionalized. The MH descendants, analyzed in both ST and HB crosses, had no significant effects on the frequency of mutant. Based on the results and on the experimental conditions mentioned in this study, it was concluded that MWCNTs were not mutagenic in D. melanogaster. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Multi-walled carbon nanotubes (Baytubes): approach for derivation of occupational exposure limit.

    PubMed

    Pauluhn, Jürgen

    2010-06-01

    Carbon nanotubes come in a variety of types, but one of the most common forms is multi-walled carbon nanotubes (MWCNT). This paper focuses on the dose-response and time course of pulmonary toxicity of Baytubes, a more flexible MWCNT type with the tendency to form assemblages of nanotubes. This MWCNT has been examined in previous single and repeated exposure 13-week rat inhalation studies. Kinetic endpoints and the potential to translocate to extrapulmonary organs have been examined during postexposure periods of 3 and 6 months, respectively. The focus of both studies was to compare dosimetric endpoints and the time course of pulmonary inflammation characterized by repeated bronchoalveolar lavage and histopathology during the respective follow-up periods. To better understand the etiopathology of pulmonary inflammation and time-related lung remodeling, two metrics of retained lung dose were compared. The first used the mass metric based on the exposure concentration obtained by filter analyses and aerodynamic particle size of airborne MWCNT. The second was based on calculated volumetric lung burdens of retained MWCNT. Kinetic analyses of lung burdens support the conclusion that Baytubes, in principal, act like poorly soluble agglomerated carbonaceous particulates. However, the difference in pulmonary toxic potency (mass-based) appears to be associated with the low-density (approximately 0.1-0.3g/m(3)) of the MWCNT assemblages. Of note is that assemblages of MWCNT were found predominantly both in the exposure atmosphere and in digested alveolar macrophages. Isolated fibers were not observed in exposure atmospheres or biological specimens. All findings support the conclusion that the low specific density of microstructures was conducive to attaining the volumetric lung overload-related inflammatory response conditions earlier than conventional particles. Evidence of extrapulmonary translocation or toxicity was not found in any study. Thus, pulmonary overload is

  14. Electron irradiation-induced change of structure and damage mechanisms in multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yang, Jian-Qun; Li, Xing-Ji; Liu, Chao-Ming; Ma, Guo-Liang; Gao, Feng

    2015-11-01

    Owing to their unique structure and excellent electrical property, carbon nanotubes (CNTs) as an ideal candidate for making future electronic components have great application potentiality. In order to meet the requirements for space application in electronic components, it is necessary to study structural changes and damage mechanisms of multi-walled carbon nanotubes (MWCNTs), caused by the irradiations of 70 and 110 keV electrons. In the paper, the changes of structure and damage mechanisms in the irradiated MWCNTs, induced by the irradiations of 70 and 110 keV electrons, are investigated. The changes in surface morphology and structure of the irradiated MWCNT film are characterized using scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, x-ray diffraction analysis (XRD), and electron paramagnetic resonance (EPR) spectroscopy. It is found that the MWCNTs show different behaviors in structural changes after 70 and 110 keV electron irradiation due to different damage mechanisms. SEM results reveal that the irradiation of 70 keV electrons does not change surface morphology of the MWCNT film, while the irradiation of 110 keV electrons with a high fluence of 5 × 1015 cm-2 leads to evident morphological changes, such as the formation of a rough surface, the entanglement of nanotubes and the shrinkage of nanotubes. Based on Raman spectroscopy, XPS, and XRD analyses, it is confirmed that the irradiation of 70 keV electrons increases the interlayer spacing of the MWCNTs and disorders their structure through electronic excitations and ionization effects, while the irradiation of 110 keV electrons obviously reduces the interlayer spacing of the MWCNTs and improves their graphitic order through knock-on atom displacements. The improvement of the irradiated MWCNTs by 110 keV electrons is attributed to the restructuring of defect sites induced by knock-on atom displacements. EPR spectroscopic analyses reveal that the MWCNTs exposed

  15. ;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.

  16. Comparison of cytotoxic and inflammatory responses of pristine and functionalized multi-walled carbon nanotubes in RAW 264.7 mouse macrophages.

    PubMed

    Zhang, Ting; Tang, Meng; Kong, Lu; Li, Han; Zhang, Tao; Zhang, Shanshan; Xue, Yuying; Pu, Yuepu

    2012-06-15

    The increased application of carbon nanotubes (CNTs) has raised the level of public concern regarding possible toxicities. Using in vitro cellular assays, we were able to assess the immunotoxicity of pristine multi-wall carbon nanotubes (MWCNTs) and their derivatives, covalently functionalized with carboxyl (COOH) or polyethylene glycol (PEG), in rodent macrophage cells. Moreover, special focus was placed on the role of surface modification and nanotubes aggregation on toxicity. Results showed that pristine MWCNTs reduce cell viability compared with functionalized MWCNTs in RAW 264.7 macrophages when incubated at concentrations of 25, 50, 100, 200, 400, and 800 μg/mL. However, in addition to causing cytotoxicity, functionalized MWCNTs induce serious inflammatory responses, as indicated by the production of inflammatory cytokines including TNF-α, IL-1β and IL-6 at various MWCNTs concentrations (25, 50, 100, and 200 μg/mL). Particle surface modification and dispersion status in biological medium were key factors in determining cy