Science.gov

Sample records for multi-walled carbon nanotubes

  1. Oxidative biodegradation of single- and multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Russier, Julie; Ménard-Moyon, Cécilia; Venturelli, Enrica; Gravel, Edmond; Marcolongo, Gabriele; Meneghetti, Moreno; Doris, Eric; Bianco, Alberto

    2011-03-01

    In this study we compare the biodegradation of both single-walled (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) using two different oxidative conditions. In particular, we demonstrate that oxidized multi-walled carbon nanotubes are highly degraded, although not to completeness when treated with horseradish peroxidase (HRP) in the presence of hydrogen peroxide.In this study we compare the biodegradation of both single-walled (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) using two different oxidative conditions. In particular, we demonstrate that oxidized multi-walled carbon nanotubes are highly degraded, although not to completeness when treated with horseradish peroxidase (HRP) in the presence of hydrogen peroxide. Electronic supplementary information (ESI) available: Experimental details, additional TEM images and DLS diagrams. See DOI: 10.1039/c0nr00779j

  2. Ag-catalysed cutting of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    La Torre, A.; Rance, G. A.; Miners, S. A.; Herreros Lucas, C.; Smith, E. F.; Fay, M. W.; Zoberbier, T.; Giménez-López, M. C.; Kaiser, U.; Brown, P. D.; Khlobystov, A. N.

    2016-04-01

    In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon-carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes.

  3. Ag-catalysed cutting of multi-walled carbon nanotubes.

    PubMed

    La Torre, A; Rance, G A; Miners, S A; Herreros Lucas, C; Smith, E F; Fay, M W; Zoberbier, T; Giménez-López, M C; Kaiser, U; Brown, P D; Khlobystov, A N

    2016-04-29

    In this work, the cutting of carbon nanotubes is investigated using silver nanoparticles deposited on arc discharge multi-walled carbon nanotubes. The composite is subsequently heated in air to fabricate shortened multi-walled nanotubes. Complementary transmission electron microscopy and spectroscopy techniques shed light on the cutting mechanism. The nanotube cutting is catalysed by the fundamental mechanism based on the coordination of the silver atoms to the π-bonds of carbon nanotubes. As a result of the metal coordination, the strength of the carbon-carbon bond is reduced, promoting the oxidation of carbon at lower temperature when heated in air, or lowering the activation energy required for the removal of carbon atoms by electron beam irradiation, assuring in both cases the cutting of the nanotubes.

  4. Resistance-based biosensor of Multi-Walled Carbon Nanotubes.

    PubMed

    Kolosovas-Machuca, E S; Vera-Reveles, G; Rodríguez-Aranda, M C; Ortiz-Dosal, L C; Segura-Cardenas, Emmanuel; Gonzalez, Francisco J

    2015-01-01

    Multi-Walled Carbon Nanotubes (MWNTs) are a good choice for resistive biosensors due to their great resistance changes when immunoreactions take place, they are also low-cost, more biocompatible than single-walled carbon nanotubes, and resistive measurement equipment is usually not expensive and readily available. In this work a novel resistive biosensor based on the immobilization of an antigen through a silanization process over the surface of Multi-Walled Carbon Nanotubes (MWNTs) is reported. Results show that the biosensor increases its conductivity when adding the antigen and decreases when adding the antibody making them good candidates for disease diagnosis.

  5. Tungsten disulphide coated multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Whitby, R. L. D.; Hsu, W. K.; Boothroyd, C. B.; Kroto, H. W.; Walton, D. R. M.

    2002-06-01

    Multi-walled carbon nanotubes (MWCNs), coated with ordered WS 2 mono- or multi-layers, are generated by pyrolysing H 2S/N 2 over MWCNs thinly coated with WO 3. High-resolution transmission electron microscopy (HRTEM) reveals the presence of hexagonal WS 2 arrays in the tube surface, consistent with the WS 2 simulated structure.

  6. Thin micropatterned multi-walled carbon nanotube films for electrodes

    NASA Astrophysics Data System (ADS)

    Halonen, Niina; Mäklin, Jani; Rautio, Anne-Riikka; Kukkola, Jarmo; Uusimäki, Antti; Toth, Geza; Reddy, Leela Mohana; Vajtai, Robert; Ajayan, Pulickel M.; Kordas, Krisztian

    2013-09-01

    Micropatterned electrodes based on thin multi-walled carbon nanotube films are grown by catalytic chemical vapour deposition on lithographically defined quartz and Inconel alloy substrates. The electrical contact at the interface between the root of the nanotube arrays and the thin Ti hardmask layer on the quartz surface is found to be poor disabling proper capacitive characteristics. On the other hand, nanotube-Inconel electrodes show low series resistance and good electric double layer capacitor operation close to that of ideal devices. Patterning of the electrodes enhances both specific capacitance and power in reference to non-patterned bulk carbon nanotube film electrodes.

  7. 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...

  8. 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...

  9. 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...

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

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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...

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

    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 § 721.10274 Multi-walled carbon nanotubes (generic) (P-09-188). (a) Chemical... as multi-walled carbon nanotubes (PMN P-09-188) is subject to reporting under this section for the...

  17. 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...

  18. Impact of multi-walled carbon nanotubes on aquatic species.

    PubMed

    Asharani, P V; Serina, N G B; Nurmawati, M H; Wu, Y L; Gong, Z; Valiyaveettil, S

    2008-07-01

    To understand the environmental impacts of carbon nanotubes (CNTs), the toxicity study was carried out with water-soluble multi-walled carbon nanotubes (MWCNTs) using zebrafish (Danio rerio) as a model system. Zebrafish embryos were treated with different concentrations of MWCNTs. Teratogenic effects were evaluated through changes in embryonic development after 24 hours post-fertilization (hpf), 48 hpf and 72 hpf. No observable effect concentration (NOEC) was at 40 microg/mL. Lowest effect concentration (LOEC) of MWCNTs which caused significant phenotypic defects in zebrafish embryo was 60 microg/mL. At concentration above 60 microg/mL, slimy mucus like coating was observed around the embryo. At high concentrations, MWCNTs was found to be involved in the apoptosis, delayed hatching and formation of abnormal spinal chords. Thus, the toxicity of multi-walled carbon nanotubes is concentration dependent.

  19. 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...

  20. 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...

  1. Multi-walled carbon nanotubes plastic NH3 gas sensor

    NASA Astrophysics Data System (ADS)

    Isa, Siti S. Mat; Ramli, Muhammad M.; Jamlos, M. F.; Hambali, N. A. M. Ahmad; Isa, M. Mohamad; Kasjoo, S. R.; Ahmad, N.; Nor, N. I. M.; Khalid, N.

    2017-03-01

    Multi-walled Carbon Nanotubes (MWCNTs) functionalized -COOH was used as the sensing material. The MWCNTs suspension was then deposited on the plastic substrate using vacuum filtration method, hence created uniform thin film carbon nanotubes network. Plastic membrane was chosen as the substrate in order to produce flexible, lightweight, wearable and low cost sensor. This device was exposed to ammonia gas (NH3) at two different concentrations; 19.2 and 231.4 ppm. The device shows high sensitivity at 23.4 % when exposed to 231.4 ppm NH3 and less sensitivity at 4.39 % for 19.2 ppm NH3 exposure.

  2. Covalent functionalization of multi-walled carbon nanotubes by lipase

    NASA Astrophysics Data System (ADS)

    Shi, Qing; Yang, Dong; Su, Yanlei; Li, Jian; Jiang, Zhongyi; Jiang, Yanjun; Yuan, Weikang

    2007-12-01

    Lipase from Candida rugosa was covalently anchored onto acid-treated multi-walled carbon nanotubes (MWNTs) through a self-catalytic mechanism. A variety of characterization techniques including FTIR, Raman spectroscopy, and XPS were employed to demonstrate the formation of the ester linkage between lipase and MWNTs. The MWNTs-lipase biocomposites showed significantly increased solubility in some common-used organic solvents, such as THF, DMF and chloroform. This study may offer a novel and facile route for covalent modification of carbon nanotubes, and expand the potential utilization of both lipases and MWNTs in the fields of biocatalyst and biosensor.

  3. Assessment of Human Lung Macrophages After Exposure to Multi-Walled Carbon Nanotubes. Part 1. Cytotoxicity

    DTIC Science & Technology

    2011-01-01

    Macrophages After Exposure to Multi-Walled Carbon Nanotubes Part I. Cytotoxicity Lin Zhu13, Amanda M. Schrand1, Andrey A. Voevodin4, Dong Wook Chang3...RXBT, Wright-Patterson AFB, OH 45433-5707, USA Due to the widespread production and use of carbon nanotubes in almost every area of science (i.e...cells after exposure to unpurified or acid- purified multi-walled carbon nanotubes . Cells were incubated with multi-walled carbon nanotubes and

  4. Superconducting Mechanism in multi-walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Jihn

    2008-03-01

    Recently Japanese group led by Haruyama [1] reported the significant enhancement of superconductivity, i.e., Tc=12K, in end-bonded Multi-walled Carbon Nanotubes. We can explain the enhancement by the electron confinement in the lateral direction, i.e., between the inner and outer cylinders, because electron density correlation enhances the phonon-mediated superconductivity. In other words, superconductivity in the (multi-walled) Carbon Nanotubes is due to the electron-phonon interaction and Tc is enhanced due to the density correlation caused by the confinement. First, we use simple concentric rings to estimate the Tc enhancement using the BCS theory. Next, we use the tight-binding model to calculate the Tc increase more accurately. In this context, this experimental result is very similar to the enhancement of Tc=15K in 4 angstrom single-walled Carbon Nanotubes by Tang et al. [2]. [1] I. Takesue et al., Phys. Rev. Lett., Vol. 96, 057001 (2006). [2] Z. K. Tang et al., Science, Vol. 292, 2462 (2001).

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

    PubMed Central

    2012-01-01

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

  6. 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.

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

    PubMed

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

    2017-02-24

    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.

  8. 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.

  9. Ultralong aligned multi-walled carbon nanotube for electrochemical sensing.

    PubMed

    Punbusayakul, Niramol; Ci, Lijie; Talapatra, Saikat; Surareungchai, Werasak; Ajayan, Pulickel M

    2008-04-01

    We have investigated electrochemical sensing properties of electrodes fabricated with ultralong aligned multi-walled carbon nanotube (MWNT) bundles synthesized using water-assisted chemical vapor deposition on aluminum (Al) and iron (Fe) coated silicon wafer with ethylene and argon/hydrogen gas as carbon source and buffer gas respectively. Cyclic voltammograms performed on these electrodes show diffusion-controlled-reversible reaction. The dominance of radial diffusion mass transport at these electrodes was also indicated by sigmoidal-shaped voltammograms obtained at various scan rates. These electrodes were able to sense very low concentration of ascorbic acid (approximately 0.7 microM) and dopamine (approximately 1.87 microM), two model species often used in electro-analysis. The excellent electrochemical properties along with good single species detection ability suggest that these MWNTs are promising electrode materials for developing very sensitive chemical and/or biological sensors.

  10. 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.

  11. 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.

  12. Computer controlled multi-walled carbon nanotube inhalation exposure system.

    PubMed

    McKinney, Walter; Chen, Bean; Frazer, Dave

    2009-10-01

    Inhalation exposure systems are necessary tools for determining the dose-response relationship of inhaled toxicants under a variety of exposure conditions. The objective of this project was to develop an automated computer controlled system to expose small laboratory animals to precise concentrations of airborne multi-walled carbon nanotubes (MWCNT). An aerosol generator was developed which was capable of suspending a respirable fraction of multi-walled carbon nanotubes from bulk material. The output of the generator was used to expose small laboratory animals to constant aerosol concentrations up to 12 mg/m(3). Particle distribution and morphology of the MWCNT aerosol delivered to the exposure chamber were measured and compared to samples previously taken from air inside a facility that produces MWCNT. The comparison showed the MWCNT generator was producing particles similar in size and shape to those found in a work environment. The inhalation exposure system combined air flow controllers, particle monitors, data acquisition devices, and custom software with automatic feedback control to achieve constant and repeatable exposure chamber temperature, relative humidity, pressure, aerosol concentration, and particle size distribution. The automatic control algorithm was capable of maintaining the mean aerosol concentration to within 0.1 mg/m(3) of the selected target value, and it could reach 95% of the target value in less than 10 minutes during the start-up of an inhalation exposure. One of the major advantages of this system was that once the exposure parameters were selected, a minimum amount of operator intervention was required over the exposure period.

  13. 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

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Multi-walled carbon nanotubes (generic... Significant New Uses for Specific Chemical Substances § 721.10266 Multi-walled carbon nanotubes (generic) (P... chemical substances identified generically as multi-walled carbon nanotubes (PMNs P-08-733 and P-08-734...

  15. 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).

  16. Polymer Grafted Janus Multi-Walled Carbon Nanotubes

    SciTech Connect

    Priftis, Dimitrios; Sakellariou, Georgios; Baskaran, Durairaj; Mays, Jimmy; Hadjichristidis, Nikos

    2009-01-01

    We describe a novel and facile strategy to modify the surface of carbon nanotubes (CNTs) with two chemically different polymer brushes utilizing the grafting from technique. A [4 + 2] Diels Alder cycloaddition reaction was used to functionalize multi-walled carbon nanotubes (MWNTs) with two different precursor initiators, one for ring opening polymerization (ROP) and one for atom transfer radical polymerization (ATRP). The binary functionalized MWNTs were used for the simultaneous surface initiated polymerizations of different monomers resulting in polymer grafted MWNTs that can form Janus type structures under appropriate conditions. 1H NMR, FTIR and Raman spectra showed that the precursor initiators were successfully synthesized and covalently attached on the CNT surface. Thermogravimetric analysis (TGA) revealed that the grafted polymer content varies when different monomer ratios and polymerization times are used. The presence of an organic layer around the CNTs was observed through transmission electron microscopy (TEM). Differential scanning calorimetry (DSC) proved that the glass transition (Tg) and melting (Tm) temperatures of the grafted polymers are affected by the presence of the CNTs, while circular dichroism (CD) spectra indicated that the PLLA ahelix conformation remains intact.

  17. Functionalized multi-walled carbon nanotubes as affinity ligands

    NASA Astrophysics Data System (ADS)

    Yu, L.; Li, C. M.; Zhou, Q.; Gan, Y.; Bao, Q. L.

    2007-03-01

    Functionalization of carbon nanotubes is very challenging for their applications. The paper here describes a new method to functionalize multi-walled carbon nanotubes (MWCNTs) as specific affinity adsorbents. MWCNTs were acid purified and pretreated with (3-aminopropyl)-triethoxysilane (APTES) in order to introduce abundant amino groups on the surface of MWCNTs. After the conversion of amino groups to carboxyl groups by succinic acid anhydride, MWCNTs were attached to protein A or aminodextran using 1-ethyl-3,3' (dimethylamion)-propylcarbodiimide as a biofunctional crosslinker. The incorporation of aminodextran as a spacer arm noticeably increased the binding capacity of the APTES-modified MWCNTs for protein A. The application of affinity MWCNTs for purification of immunoglobulin G was then evaluated. The affinity of MWCNTs with AMD spacer exhibited a high adsorption capacity of ~361 µg IgG/mg MWCNT (wet basis). About 75% of bound IgG was eluted from affinity MWCNTs (ANT-I and ANT-II) and ELISA confirmed that the biological activity of IgG was well preserved during the course of affinity separation. The functionalized MWCNTs could be potentially used in affinity chromatography.

  18. Using Photosensitive Dye To Improve Multi Walled Carbon Nanotubes Dispersion

    NASA Astrophysics Data System (ADS)

    Díaz Costanzo, Guadalupe; Goyanes, Silvia; Ledesma, Silvia

    2011-01-01

    As already well-known, the outstanding mechanical and electrical properties of carbon nanotubes (CNT) are partially lost when CNT aggregate. The fact that CNT tend to aggregate makes difficult to put them into a host matrix, for example. Until now, achieving stable dispersions of CNT is still a challenge. In the present work, we show that the addition of an azobenzene derivative, Disperse Orange 3 (DO3) to dispersions of multi walled carbon nanotubes (MWCNT) in the organic solvent tetrahydrofuran (THF) efficiently helps debundling MWCNT and makes dispersions stable for days. We report UV-Vis optical absorption experiments that suggest an interaction between MWCNT and DO3 molecules following the behavior qualitatively observed. Dispersions with MWCNT and DO3 in THF were observed qualitatively over time. Successful suspensions (for the higher DO3 concentrations studied) were stable for several days. Also, we prepared polymeric films doped with MWCNT non-covalent functionalized with DO3 in one of the proper DO3/MWCNT weight relation where stable supensions were obtained. In this study we show preliminary results where the optical response of these samples was also measured.

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

    PubMed

    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.

  20. 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.

  1. Facile approach to prepare multi-walled carbon nanotubes/graphene nanoplatelets hybrid materials

    PubMed Central

    2013-01-01

    A facile approach was developed to prepare multi-walled carbon nanotubes/graphene nanoplatelets hybrid materials through covalent bond formation. First, poly(acryloyl chloride) was grafted onto oxidized multi-walled carbon nanotubes through the reaction between the acyl chloride groups of poly and the hydroxyl groups of oxidized multi-walled carbon nanotubes. Second, the remaining acyl chloride groups of poly were allowed to react with the hydroxyl groups of hydroxylated graphene nanoplatelets. Scanning electron microscopy and transmission electron microscopy data showed that the multi-walled carbon nanotubes and graphene nanoplatelets were effectively connected with each other. And Fourier transform infrared spectroscopy data indicated the formation of covalent bonds between carbon nanotubes and graphene nanoplatelets. Conformational changes were monitored by Raman spectroscopy. This novel kind of carbon hybrid materials may have the potential application in a wide field, especially in increasing the toughness and strength of the matrix resin. PMID:23680189

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

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

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

  3. Surface studies of hydroxylated multi-wall carbon nanotubes

    SciTech Connect

    Bradley, Robert; Cassity, Kelby; Andrews, Rodney; Meier, Mark; Osbeck, Susan; Andreu, Aurik; Johnston, Colin; Crossley, Alison

    2012-01-01

    CVD grown MWCNTs, of typical diameter 5 to 50 nm and with approximately 15-20 concentric graphene layers in the multi-walls, have been surface functionalised using the Fenton hydroxylation reaction. HRTEM reveals little physical difference between the treated and untreated materials; images from both exhibit similar multi-wall structure and contain evidence for some low-level disruption of the very outermost layers. Raman spectra from the two types of nanotubes are almost identical displaying the disorder (D) peaks at approximately 1350 cm{sup -1} and graphite (G) peaks at approximately 1580 cm{sup -1}, characteristic of graphene-based carbon materials, in approximately equal intensity ratios. Equilibrium adsorption data for nitrogen at 77 K leads to BET surface areas of 60.4 m{sup 2} g{sup -1} for the untreated and 71.8 m{sup 2} g{sup -1} for the hydroxylated samples; the increase in area being due to separation of the tube-bundles during functionalization. This is accompanied by a decrease in measured porosity, mostly at high relative pressures of nitrogen, i.e. where larger (meso 2-5 nm and macro >5 nm) pores are being filled, which is consistent with an attendant loss of inter-tube capillarity. X-ray photoelectron spectroscopy (XPS) shows that hydroxylation increases the nanotube surface oxygen level from 4.3 at.% to 22.3 at.%; chemical shift data indicate that approximately 75% of that oxygen is present as hydroxyl (-OH) groups. Water vapour adsorption by the hydroxylated surfaces leads to Type II isotherms which are characteristic of relatively high numbers of hydrogen bonding interactions compared to the untreated materials which exhibit Type III curves. This difference in polar surface energy is confirmed by calorimetric enthalpies of immersion in water which are -54 mJ m{sup -2} for the untreated and -192 mJ m{sup -2} for the hydroxylated materials. The treated materials therefore have significantly increased water wettability/dispersivity and a greater

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

    NASA Astrophysics Data System (ADS)

    Meng, Qing-jie; Zhang, Xing-xiang; Bai, Shi-he; Wang, Xue-chen

    2007-12-01

    An in situ polymerization process was used to prepare poly (methyl methacrylate) (PMMA)-functionalized carboxyl multi-walled carbon nanotubes using carboxylate carbon nanotubes and methyl methacrylate as reactants and benzoyl peroxide as an initiator agent. The functionalized multi-walled carbon nanotubes were characterized using transmission electron microscope, scanning electron microscope, nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis and Raman. The results indicate that the PMMA chains are covalently linked with the surface of carboxylate carbon nanotubes. The surface morphology is controlled by the content of carboxylate carbon nanotubes in the reactants. The PMMA functionalized multi-walled carbon nanotubes are soluble in deuterated chloroform. The storage modulus and tanδ magnitude increase as the content of CCNTs increases up to 0.3%.

  5. Spectroscopic investigations on oxidized multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Anandhi, C. M. S.; Premkumar, S.; Asath, R. Mohamed; Mathavan, T.; Benial, A. Milton Franklin

    2016-05-01

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

  6. Combined torsional buckling of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lu, Y. J.; Wang, X.

    2006-08-01

    This paper reports the results of an investigation on combined torsional buckling of an individual multi-walled carbon nanotube (MWNT) under combined torque and axial loading. Here, a multiple shell model is adopted and the effect of van der Waals forces between two adjacent tubes is taken into account. According to the ratio of radius to thickness, MWNTs discussed in this paper are classified into three types: thin, thick and nearly solid. The critical shear stress and the combined buckling mode are calculated for three types of MWNTs under combined torque and axial loading. Results carried out show that the buckling mode (m, n) corresponding to the critical shear stress is unique, which is obviously different from the purely axial compression buckling of an individual MWNT. Numerical results also show that the critical shear stresses and the corresponding buckling modes of MWNTs under combined torque and axial loading are dependent on the axial loading form and the types of MWNTs. The new features and meaningful numerical results in the present work on combined buckling of MWNTs under combined torque and axial loading may be used as a useful reference for the designs of nano-drive devices and rotational actuators in which MWNTs act as basic elements.

  7. Field Emission Stability of Individual Multi-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Fujieda, Tadashi; Okai, Makoto; Tokumoto, Hiroshi

    2009-02-01

    We investigated the emission stability of individual multi-walled carbon nanotubes (MWNTs) and clarified the mechanism of emission current instability. An initial decrease in the emission current, which is generally seen in the case of metal emitters, was hardly observed. Furthermore, the current fluctuation was much lower than that for a metal emitter, and the peak-to-peak fluctuation was less than 2% when the emission pattern was pentagonal. However, spikelike and steplike noises occurred, with a frequency approximately proportional to the product of the emission current and the background pressure. These noises may be caused by physical adsorption and ion impact desorption of residual gas molecules. The number of these noise events depended on the emission pattern: it was much greater in the case of a nonpentagonal emission pattern than in the case of a pentagonal emission pattern. This type of current noise is considered to be due to ionic-collision-induced damage at the surface of the tip when the emission pattern is nonpentagonal.

  8. Multi-walled carbon nanotube-based RF antennas.

    PubMed

    Elwi, Taha A; Al-Rizzo, Hussain M; Rucker, Daniel G; Dervishi, Enkeleda; Li, Zhongrui; Biris, Alexandru S

    2010-01-29

    A novel application that utilizes conductive patches composed of purified multi-walled carbon nanotubes (MWCNTs) embedded in a sodium cholate composite thin film to create microstrip antennas operating in the microwave frequency regime is proposed. The MWCNTs are suspended in an adhesive solvent to form a conductive ink that is printed on flexible polymer substrates. The DC conductivity of the printed patches was measured by the four probe technique and the complex relative permittivity was measured by an Agilent E5071B probe. The commercial software package, CST Microwave Studio (MWS), was used to simulate the proposed antennas based on the measured constitutive parameters. An excellent agreement of less than 0.2% difference in resonant frequency is shown. Simulated and measured results were also compared against identical microstrip antennas that utilize copper conducting patches. The proposed MWCNT-based antennas demonstrate a 5.6% to 2.2% increase in bandwidth, with respect to their corresponding copper-based prototypes, without significant degradation in gain and/or far-field radiation patterns.

  9. Multi-Walled Carbon Nanotubes Inhibit Breast Cancer Cell Migration.

    PubMed

    Graham, Elizabeth G; Wailes, Elizabeth M; Levi-Polyachenko, Nicole H

    2016-02-01

    According to the American Cancer Society, breast cancer is the second leading cause of cancer death in the US. Cancerous cells may have inadequate adhesions to the extracellular matrix and adjacent cells. Previous work has suggested that restoring these contacts may negate the cancer phenotype. This work aims to restore those contacts using multi-walled carbon nanotubes (MWNTs). Varying concentrations of carboxylated MWNTs in water, with or without type I collagen, were dried to create a thin film upon which one of three breast cell lines were seeded: cancerous and metastatic MDA- MB-231 cells, cancerous but non-metastatic MCF7 cells, or non-cancerous MCF10A cells. Proliferation, adhesion, scratch and autophagy assays, western blots, and immunochemical staining were used to assess adhesion and E-cadherin expression. Breast cancer cells grown on a MWNT-collagen coated surface displayed increased adhesion and decreased migration which correlated with an increase in E-cadherin. This work suggests an alternative approach to cancer treatment by physically mediating the cells' microenvironment.

  10. Multi-walled carbon nanotube-based RF antennas

    NASA Astrophysics Data System (ADS)

    Elwi, Taha A.; Al-Rizzo, Hussain M.; Rucker, Daniel G.; Dervishi, Enkeleda; Li, Zhongrui; Biris, Alexandru S.

    2010-01-01

    A novel application that utilizes conductive patches composed of purified multi-walled carbon nanotubes (MWCNTs) embedded in a sodium cholate composite thin film to create microstrip antennas operating in the microwave frequency regime is proposed. The MWCNTs are suspended in an adhesive solvent to form a conductive ink that is printed on flexible polymer substrates. The DC conductivity of the printed patches was measured by the four probe technique and the complex relative permittivity was measured by an Agilent E5071B probe. The commercial software package, CST Microwave Studio (MWS), was used to simulate the proposed antennas based on the measured constitutive parameters. An excellent agreement of less than 0.2% difference in resonant frequency is shown. Simulated and measured results were also compared against identical microstrip antennas that utilize copper conducting patches. The proposed MWCNT-based antennas demonstrate a 5.6% to 2.2% increase in bandwidth, with respect to their corresponding copper-based prototypes, without significant degradation in gain and/or far-field radiation patterns.

  11. Spectroscopic investigations on oxidized multi-walled carbon nanotubes

    SciTech Connect

    Anandhi, C. M. S.; Premkumar, S.; Asath, R. Mohamed; Mathavan, T.; Benial, A. Milton Franklin

    2016-05-06

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

  12. Microtubule guiding in a multi-walled carbon nanotube circuit.

    PubMed

    Sikora, Aurélien; Ramón-Azcón, Javier; Sen, Mustafa; Kim, Kyongwan; Nakazawa, Hikaru; Umetsu, Mitsuo; Kumagai, Izumi; Shiku, Hitoshi; Matsue, Tomokazu; Teizer, Winfried

    2015-08-01

    In nanotechnological devices, mass transport can be initiated by pressure driven flow, diffusion or by employing molecular motors. As the scale decreases, molecular motors can be helpful as they are not limited by increased viscous resistance. Moreover, molecular motors can move against diffusion gradients and are naturally fitted for nanoscale transportation. Among motor proteins, kinesin has particular potential for lab-on-a-chip applications. It can be used for sorting, concentrating or as a mechanical sensor. When bound to a surface, kinesin motors propel microtubules in random directions, depending on their landing orientation. In order to circumvent this complication, the microtubule motion should be confined or guided. To this end, dielectrophoretically aligned multi-walled-carbon nanotubes (MWCNT) can be employed as nanotracks. In order to control more precisely the spatial repartition of the MWCNTs, a screening method has been implemented and tested. Polygonal patterns have been fabricated with the aim of studying the guiding and the microtubule displacement between MWCNT segments. Microtubules are observed to transfer between MWCNT segments, a prerequisite for the guiding of microtubules in MWCNT circuit-based biodevices. The effect of the MWCNT organization (crenellated or hexagonal) on the MT travel distance has been investigated as well.

  13. 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...

  14. 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...

  15. Assessment of Human Lung Macrophages After Exposure to Multi-Walled Carbon Nanotubes. Part 2. DNA Damage

    DTIC Science & Technology

    2011-01-01

    to Multi-Walled Carbon Nanotubes Part II. DNA Damage Lin Zhu13, Amanda M. Schrand1, Andrey A. Voevodin4, Dong Wook Chang3, Liming Dai2∗, and Saber M...5707 Due to the widespread production and use of carbon nanotubes in almost every area of science (i.e., drug delivery, biosensors, fuel cells and...purified multi-walled carbon nanotubes . Cells were incubated with multi-walled carbon nanotubes and assessed for DNA damage response via fluorescent

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  18. Wetting behavior of multi-walled carbon nanotube nanofluids.

    PubMed

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

    2017-03-10

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

  1. 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...

  2. 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...

  3. Blood biocompatibility of surface-bound multi-walled carbon nanotubes.

    PubMed

    Gaffney, Alan M; Santos-Martinez, Maria J; Satti, Amro; Major, Terry C; Wynne, Kieran J; Gun'ko, Yurii K; Annich, Gail M; Elia, Giuliano; Radomski, Marek W

    2015-01-01

    Blood clots when it contacts foreign surfaces following platelet activation. This can be catastrophic in clinical settings involving extracorporeal circulation such as during heart-lung bypass where blood is circulated in polyvinyl chloride tubing. Studies have shown, however, that surface-bound carbon nanotubes may prevent platelet activation, the initiator of thrombosis. We studied the blood biocompatibility of polyvinyl chloride, surface-modified with multi-walled carbon nanotubes in vitro and in vivo. Our results show that surface-bound multi-walled carbon nanotubes cause platelet activation in vitro and devastating thrombosis in an in vivo animal model of extracorporeal circulation. The mechanism of the pro-thrombotic effect likely involves direct multi-walled carbon nanotube-platelet interaction with Ca(2+)-dependant platelet activation. These experiments provide evidence, for the first time, that modification of surfaces with nanomaterials modulates blood biocompatibility in extracorporeal circulation.

  4. Photoresponse from noble metal nanoparticles-multi walled carbon nanotube composites

    SciTech Connect

    Scarselli, M.; Camilli, L.; Castrucci, P.; De Crescenzi, M.; Matthes, L.; Pulci, O.; Gatto, E.; Venanzi, M.

    2012-12-10

    In this Letter, we investigated the photo-response of multi wall carbon nanotube-based composites obtained from in situ thermal evaporation of noble metals (Au, Ag, and Cu) on the nanotube films. The metal deposition process produced discrete nanoparticles on the nanotube outer walls. The nanoparticle-carbon nanotube films were characterized by photo-electrochemical measurements in a standard three electrode cell. The photocurrent from the decorated carbon nanotubes remarkably increased with respect to that of bare multiwall tubes. With the aid of first-principle calculations, these results are discussed in terms of metal nanoparticle-nanotube interactions and electronic charge transfer at the interface.

  5. Effects of Gases on Field Emission from Single and Multi-Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Wadhawan, A.; Stephens, K.; Stallcup, R., II; Perez, J.; Physics Department Collaboration

    2001-03-01

    We report the effects of O_2, H_2, and Ar exposure on the field emission properties of single and multi-wall carbon nanotubes. The field emission current vs. voltage curves and field emission current vs. time were measured as a function of gas exposure at 10-8 Torr over a period of approximately 8 hours. The data were collected using an automated system running under Labview. We find that H2 and Ar exposure do not significantly affect the field emission properties of either single or multi-walled carbon nanotubes. However, O2 exposure degrades the field emission properties of multi-wall tubes more than those of single-wall tubes. After O2 exposure, the turn-on voltage for multi-wall tubes increased fromm 300 to 500 volts, while the turn-on voltage for single-wall tubes increased from 200 to 250 volts. An explanation of these results will be discussed.

  6. A multi-wall carbon nanotube tower electrochemical actuator.

    PubMed

    Yun, YeoHeung; Shanov, Vesselin; Tu, Yi; Schulz, Mark J; Yarmolenko, Sergey; Neralla, Sudhir; Sankar, Jag; Subramaniam, Srinivas

    2006-04-01

    Patterned multiwall carbon nanotube arrays up to four millimeters long were synthesized using chemical vapor deposition. Electrochemical actuation of a nanotube array tower was demonstrated in a 2 M NaCl solution at frequencies up to 10 Hz with 0.15% strain using a 2 V square wave excitation. The synthesis and electrochemical modeling approach outlined in the paper provide a foundation for the design of nanotube smart materials that actuate and are load bearing.

  7. Electrical Conduction Mechanism in Chemical Vapour Deposition Grown Multi-Wall Carbon Nanotubes Film.

    PubMed

    Al-Hazmi, F S

    2015-07-01

    Multi-walled carbon nanotubes are interesting systems where different aspects of conduction are observed, mostly due to their low dimensionalities and small dimensions. Electrical conduction mechanism in multi wall carbon nanotubes film is studied. The studied multi-walled nanotubes are grown by a low pressure chemical vapour deposition system. To understand the conduction mechanism in these nanotubes, temperature dependence of conductivity of the multi wall nanotubes film over a temperature range of (400-200 K) is studied. On the basis of the results, one may suggest the thermally activated conduction mechanism for the temperature range (400-300 K). The low temperature data is fitted with the hopping conduction for the transport of charge carriers in the temperature range of 300-200 K. This hopping conduction mechanism is characterized by variable range hopping (VRH), which shows complete agreement with the Mott's type of VRH mechanism. Applying this model, a number of Mott's parameters such as density of states, hopping distance, hopping energy are calculated. The calculated values of all the studied parameters matches well the reported results on other multi-wall nanotubes film.

  8. Tensile Yielding of Multi-Wall Carbon Nanotube

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  9. Transport properties of alkali-doped multi walled carbon nanotubes.

    PubMed

    Barone, P; Barberio, M; Pingitore, V; Bonanno, A

    2012-12-01

    In this work we propose a study on electrical properties of multiwalled carbon nanotubes (MWCNT) doped with the most commonly used alkali metals. We report resistivity measurements of MWCNT exposed to doping with Li, Na, K and Cs. Our results show that, increasing the alkali exposure, the resistance of the doped sample decreases denoting a progressive sample metallization. The changes in resistivity, contrary to that observed for single walled carbon nanotubes (SWCNT) in our previous work, are independent upon the alkali properties but appear related to alkali intercalation effects in the MWCNT random network. The doping effects have been also controlled by X-ray photo electron spectroscopy (XPS). The spectra confirm the absence of chemical bonds between carbon nanotubes and alkali, validating the hypothesis of intercalation of alkali in the interstitial channels between the tubes. Our results are also confirmed by comparison between SEM images of single walled and multiwalled carbon nanotubes.

  10. 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...

  11. 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...

  12. 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...

  13. Template directed formation of nanoparticle decorated multi-walled carbon nanotube bundles with uniform diameter.

    PubMed

    Han, T Yong-Jin; Stadermann, Michael; Baumann, Theodore F; Murphy, Kristen E; Satcher, Joe H

    2011-10-28

    Bundles of multi-walled carbon nanotubes of uniform diameter decorated with Ni nanoparticles were synthesized using mesoporous silicates as templates. The ordered morphology and the narrow pore size distribution of mesoporous silicates provide an ideal platform to synthesize uniformly sized carbon nanotubes. In addition, homogeneous sub-10 nm pore sizes of the templates allow in situ formation of catalytic nanoparticles with uniform diameters which end up decorating the carbon nanotubes. The resulting carbon nanotubes are multi-walled with a uniform diameter corresponding to the pore diameter of the template used during the synthesis that are decorated with the catalysts used to synthesize them. They have a narrow size distribution which can be used in many energy related fields of research.

  14. WS2 layer formation on multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Whitby, R. L. D.; Hsu, W. K.; Boothroyd, C. B.; Brigatti, K. S.; Kroto, H. W.; Walton, D. R. M.

    Time-dependent powder X-ray-diffraction analyses reveal that the conversion of WO3 into WS2 on carbon nanotube surfaces in the presence of H2S is a one-step process. The WS2 layers grow simultaneously along the tube in the radial and axial directions.

  15. 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.

  16. 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...

  17. Highly water-soluble multi-walled carbon nanotubes amine-functionalized by supercritical water oxidation.

    PubMed

    Chun, Kyoung-Yong; Moon, In-Kyu; Han, Joo-Hee; Do, Seung-Hoe; Lee, Jin-Seo; Jeon, Seong-Yun

    2013-11-07

    Multi-walled carbon nanotubes (MWNTs) have been amine-functionalized by eco-friendly supercritical water oxidation. The facilely functionalized MWNTs have high solubility (~84 mg L(-1)) in water and 78% transmittance at 30-fold dilution. The Tyndall effect is also shown for several liquids.

  18. A possible formation mechanism of double-walled and multi-walled carbon nanotube: a molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Han, Dianrong; Luo, Chenglin; Dai, Yafei; Zhu, Xingfeng

    2016-09-01

    Molecular dynamics simulations based on an empirical potential were performed to study the interaction of graphene nanoribbons and the single-walled carbon nanotubes. The results indicated that a piece of graphene nanoribbon can form a tube structure inside or outside single-walled carbon nanotubes spontaneously under certain condition. Based on this kind of spontaneous phenomenon, we proposed a new possible formation mechanism of double walled carbon nanotube and multi-walled carbon nanotube, and suggested the possibility of controlling the structure of double-walled carbon nanotube and/or multi-walled carbon nanotube.

  19. 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.

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

    SciTech Connect

    Yue, Yanfeng; Guo, Bingkun; Qiao, Zhenan; Fulvio, Pasquale F.; Chen, Jihua; Binder, Andrew J.; Tian, Chengcheng; Dai, Sheng

    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.

  1. Finite element investigation of multi-walled carbon nanotubes as mass sensors

    NASA Astrophysics Data System (ADS)

    Rouhi, Saeed; Ansari, Reza; Nikkar, Abed

    2017-03-01

    Using the finite element method, multi-walled carbon nanotubes-based mass sensors are studied. The effects of different parameters such as number of walls of nanotube, nanotube diameter and nanotube length on the mass sensibility are explored. It is shown that the maximum sensitivity of nanotubes under clamped-free boundary conditions occurs when the mass is located at the farthest location from the clamped edge. Comparing the results of nanotubes with different walls, it is observed that single-walled carbon nanotubes are the best mass sensors. Moreover, it is represented that for large masses connected to the nanotubes, the mass sensor can only identify that an external mass added to it and the mass value is not identifiable.

  2. 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.

  3. Effects of strain rates and temperatures on the mechanical properties of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chen, X.; Wang, X.; Sheng, G. G.

    2007-04-01

    This paper reports the results of an investigation of the dynamic mechanical properties of multi-walled armchair and zigzag nanotubes under different strain rates and environmental temperatures. Based on a molecular structural mechanics model, the covalent bonds are treated as a two dimensional beam element and van der Waals forces between two adjacent tubes are firstly simulated by a nonlinear spring. The corresponding force constants of bond stretching, bond angle bending and torsional resistance in different environmental temperatures can be, respectively, obtained by computing the variation of chemical bond lengths. The result obtained reveals that the dynamic Young's modulus of the effective nanotube material increases as the strain rate increases, and decreases as the environmental temperature increases; the effect of layer numbers of multi-walled carbon nanotubes (MWCNTs) on the dynamic Young's modulus of the effective nanotube material is dependent on strain rates and environmental temperatures.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

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

    SciTech Connect

    Silambarasan, D. Vasu, V.; Iyakutti, K.; Asokan, 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.

  10. 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.

  11. The sensor based on oxidized multi-walled carbon nanotubes prepared by electrochemical method and its application

    NASA Astrophysics Data System (ADS)

    Song, Y. Z.; Yang, L.; Jiang, Q. Y.

    2015-07-01

    The sensor based on oxidized multi-walled carbon nanotubes was prepared by electrochemical method. The behavior of norepinephrine tartrate at the modified electrode was studied. It was demonstrated that modified sensor is a good electrocatalyst for norepinephrine tartrate.

  12. 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...

  13. 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...

  14. Time and temperature dependence of multi-walled carbon nanotube growth on Inconel 600.

    PubMed

    Pal, S K; Talapatra, S; Kar, S; Ci, L; Vajtai, R; Borca-Tasciuc, T; Schadler, L S; Ajayan, P M

    2008-01-30

    The growth kinetics of vertically aligned multi-walled carbon nanotubes (MWNTs) on conductive substrates is investigated by synthesizing MWNTs at different growth temperatures and measuring ex situ the length of the nanotubes as a function of growth duration. A typical 'root growth' mechanism (saturation of MWNT lengths with increasing growth duration) was observed. The value of the activation energy (E(a)≈136 ± 5 kJ mol(-1)) of the MWNT growth reaction is suggestive of carbon diffusion through the bulk of the iron catalyst particle versus diffusion on its surface. These findings will help in optimizing MWNT growth on conductive substrates for various applications.

  15. Prediction of the critical buckling load of multi-walled carbon nanotubes under axial compression

    NASA Astrophysics Data System (ADS)

    Timesli, Abdelaziz; Braikat, Bouazza; Jamal, Mohammad; Damil, Noureddine

    2017-02-01

    In this paper, we propose a new explicit analytical formula of the critical buckling load of double-walled carbon nanotubes (DWCNT) under axial compression. This formula takes into account van der Waals interactions between adjacent tubes and the effect of terms involving tube radii differences generally neglected in the derived expressions of the critical buckling load published in the literature. The elastic multiple Donnell shells continuum approach is employed for modelling the multi-walled carbon nanotubes. The validation of the proposed formula is made by comparison with a numerical solution. The influence of the neglected terms is also studied.

  16. Magnetic studies of polystyrene/iron-filled multi-wall carbon nanotube composite films

    NASA Astrophysics Data System (ADS)

    Makarova, T. L.; Zakharchuk, I.; Geydt, P.; Lahderanta, E.; Komlev, A. A.; Zyrianova, A. A.; Kanygin, M. A.; Sedelnikova, O. V.; Suslyaev, V. I.; Bulusheva, L. G.; Okotrub, A. V.

    2016-10-01

    Polystyrene/iron-filled multi-wall carbon nanotube composite films were prepared by solution processing, forge-rolling and stretching methods. Elongated iron carbide nanoparticles formed because of catalytic growth are situated inside the hollow cavity of the nanotubes. Magnetic susceptibility measurements as well as records of isothermal hysteresis loops performed in three perpendicular directions of magnetic field confirmed that the nanotubes have a preferential alignment in the matrix. Strong diamagnetic anisotropy in the composites emerges not only from the MWCNTs but also from the polystyrene matrix. The polymer sticks to the honeycomb lattice through the interaction of the π-orbitals of the phenyl ring and those of the carbon nanotube, contributing to anisotropic diamagnetic response. The contribution of iron nanoparticles to overall magnetic response strongly depends on nanotube concentration in the composite as well as on matrix-filler non-covalent stacking, which influences magnetic interparticle interactions.

  17. Supramolecular modification of multi-walled carbon nanotubes with β-cyclodextrin for better dispersibility

    NASA Astrophysics Data System (ADS)

    He, Yi; Xu, Zhonghao; Yang, Qiangbin; Wu, Feng; Liang, Lv

    2015-01-01

    A novel hybrid material based on multi-walled carbon nanotubes was synthesized using organic synthesis, and the structures of multi-walled carbon nanotube derivatives were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, 1H NMR spectroscopy, transmission electron microscopy, and scanning electron microscope. The analytical results indicated that β-cyclodextrin (β-CD) was anchored to the surface of Multi-walled carbon nanotubes (MWCNTs, OD: 10-20 nm, length: 10-30 μm) and dispersion experiments exhibited that the introduction of β-CD onto the MWCNTs would dramatically enhance the dispersion of MWCNTs in both ethanol and water media; the suspensions were found to be very stable for 2 months, and the results of this technique confirmed the experimental results. This novel technique would provide a new, simple, and facile route to prepare the modified nanomaterials based on silane-coupling agent and β-CD, and the obtained modified nanomaterials have great potential practical significance and theoretical value to develop the novel organic-inorganic hybrid material, which was very useful for water treatment and biological medicine.

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

    SciTech Connect

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

    2015-10-27

    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 m{sup 2}/g, and increases the pore volume and average size from 0.04 to 0.06 cm{sup 3}/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.

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

    PubMed Central

    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

    2015-01-01

    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 (1.2 mg/ml) or MWCNT-7 (0.1 mg/ml) increased cellular proliferation, while the highest dose of 120 mg/ml of either material decreased proliferation. ND-MWCNT and MWCNT-7 appeared to interact with SAEC at 6 h and were internalized by 24 h. ROS were elevated at 6 and 24 h in ND-MWCNT exposed cells, but only at 6 h in MWCNT-7 exposed cells. Significant alterations to the cell cycle were observed in SAEC exposed to either 1.2 mg/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. PMID:25797581

  20. 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.

  1. 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

    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.

  2. 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.

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

    PubMed

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

    2008-07-01

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

  4. 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.

  5. Electrical conductance between multi-walled carbon nanotube and Cu

    NASA Astrophysics Data System (ADS)

    Gao, Feng; Qu, Jianmin; Yao, Matthew

    2011-04-01

    Vertical MWCNT interconnects have already been investigated for vias, or even for through-wafer 3D interconnects. Several studies have been done to understand the electrical conductance of MWCNT itself. The electrical conductance at a junction between MWCNT and metals has not been studied yet. Here we reported the intershell interaction effect on the electrical conductance at the Cu/MWCNT/Cu junctions by quantum mechanics calculations. Both end- and side-contacts between MWCNT and Cu electrodes were studied. In the end-contact junction, each individual CNT in the MWCNT acts as if it is a single wave CNT. The total conductance is almost the sum of the contributions from each individual nanotube. However, in the side-contact junction, the conductance between the outermost CNT and Cu electrode is dominant, whereas the intershell interaction leads to a reduction of the total electrical conductance. This is attributed to the enhanced localization of density of states in the vicinity of Fermi level by inner tube. The authors acknowledge the financial support from Rockwell Collins Inc.

  6. Mass production of multi-wall carbon nanotubes by metal dusting process with high yield

    SciTech Connect

    Ghorbani, H.; Rashidi, A.M.; Rastegari, S.; Mirdamadi, S.; Alaei, M.

    2011-05-15

    Research highlights: {yields} Synthesis of carbon nanotubes over Fe-Ni nanoparticles supported alloy 304L. {yields} Production of carbon nanotubes with high yield (700-1000%) and low cost catalyst. {yields} Optimum growth condition is CO/H{sub 2} = 1/1, 100 cm{sup 3}/min, at 620 {sup o}C under long term repetitive thermal cycling. {yields} Possibility of the mass production by metal dusting process with low cost. -- Abstract: Carbon nanotube materials were synthesized over Fe-Ni nanoparticles generated during disintegration of the surface of alloy 304L under metal dusting environment. The metal dusting condition was simulated and optimized through exposing stainless steel samples during long term repetitive thermal cycling in CO/H{sub 2} = 1/1, total gas flow rate 100 cm{sup 3}/min, at 620 {sup o}C for 300 h. After reaction, surface morphology of the samples and also carbonaceous deposition which had grown on sample surfaces were examined by stereoscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results revealed that multi-wall carbon nanotubes could be formed over nanocatalyst generated on the alloy surface by exploiting metal dusting process. By optimization of reaction parameters the yields of carbon nanotube materials obtained were 700-1000%. Also it has been shown herein that the amount of carbon nanotube materials remarkably increases when the reaction time is extended up to 300 h, indicating a possibility of the mass production by this easy method.

  7. 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.

  8. Multi wall carbon nanotubes induce oxidative stress and cytotoxicity in human embryonic kidney (HEK293) cells.

    PubMed

    Reddy, Anreddy Rama Narsimha; Reddy, Yellu Narsimha; Krishna, Devarakonda Rama; Himabindu, Vurimindi

    2010-06-04

    The present study was aimed at evaluating the potential toxicity and the general mechanism involved in multi wall carbon nanotubes (MWCNT)-induced cytotoxicity using human embryonic kidney cell line (HEK293) cells. Two multi wall carbon nanotubes (coded as MWCNT1, size: 90-150nm and MWCNT2, size: 60-80nm) used in this study are MWCNT1 (produced by the electric arc method and size of the nanotubes was 90-150nm) and MWCNT2 (produced by the chemical vapor deposition method with size of 60-80nm). To elucidate the possible mechanisms of MWCNT induced cytotoxicity, cell viability, mitochondrial function (MTT assay), cell membrane damage (LDH assay), reduced glutathione (GSH), interleukin-8 (IL-8) and lipid peroxidation levels were quantitatively assessed under carbon nanotubes exposed (48h) conditions. Exposure of different sizes of two carbon nanotubes at dosage levels between 3 and 300mug/ml decreased cell viability in a concentration dependent manner. The IC(50) values (concentration of nanoparticles to induce 50% cell mortality) of two (MWCNT1, MWCNT2) nanoparticles were found as 42.10 and 36.95mug/ml. Exposure of MWCNT (10-100mug/ml) to HEK cells resulted in concentration dependent cell membrane damage (as indicated by the increased levels of LDH), increased production of IL-8, increased TBARS and decreased intracellular glutathione levels. The cytotoxicity and oxidative stress was significantly more in MWCNT2 exposed cells than MWCNT1. In summary, exposure of carbon nanotubes resulted in a concentration dependent cytotoxicity in cultured HEK293 cells that was associated with increased oxidative stress.

  9. Analysis of Effluent Gases During the CCVD Growth of Multi Wall Carbon Nanotubes from Acetylene

    NASA Technical Reports Server (NTRS)

    Schmitt, T. C.; Biris, A. S.; Miller, D. W.; Biris, A. R.; Lupu, D.; Trigwell, S.; Rahman, Z. U.

    2005-01-01

    Catalytic chemical vapor deposition was used to grow multi-walled carbon nanotubes on a Fe:Co:CaCO3 catalyst from acetylene. The influent and effluent gases were analyzed by gas chromatography and mass spectrometry at different time intervals during the nanotubes growth process in order to better understand and optimize the overall reaction. A large number of byproducts were identified and it was found that the number and the level for some of the carbon byproducts significantly increased over time. The CaCO3 catalytic support thermally decomposed into CaO and CO2 resulting in a mixture of two catalysts for growing the nanotubes, which were found to have outer diameters belonging to two main groups 8 to 35 nm and 40 to 60 nm, respectively.

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

    NASA Astrophysics Data System (ADS)

    Zhao, Junhua; Lu, Lixin; Rabczuk, Timon

    2014-05-01

    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.

  11. 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.

  12. 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

  13. On finite element modeling of single- and multi-walled carbon nanotubes.

    PubMed

    Rahmandoust, Moones; Ochsner, Andreas

    2012-10-01

    In this study, Single-Walled and Multi-Walled Carbon Nanotubes in their perfect forms were investigated by the Finite Element Method. Details on the modeling of the structure are provided in this paper, including the appropriate elements, the element properties that should be defined based on the atomic structure of Carbon Nanotubes and the corresponding chemical bonds. Non-covalent van der Waals interactions between two neighbor atoms as well as the required approximations for the modeling of the structures with this kind of interaction are also presented. Specific attention was dedicated to the necessity of using some time- and energy-consuming steps in the simulation process. First, the effect of simulating only a single ring of the whole structure is studied to find out if it would represent the same mechanical behavior as the long structure. Results show that by applying an appropriate set of boundary conditions, the stiffness of the shortened structure is practically equal to the long perfect structure. Furthermore, Multi-Walled Carbon Nanotube structures with and without defining the van der Waals force are studied. Based on the observations, applying the van der Waals force does not significantly influence the obtained Young's modulus of the structure in the case of a uniaxial tensile test.

  14. Effects of suspended multi-walled carbon nanotubes on daphnid growth and reproduction.

    PubMed

    Alloy, Matthew M; Roberts, Aaron P

    2011-10-01

    Relatively little is known about the potential impacts of engineered nanoparticles on aquatic biota. Particularly relevant to aquatic ecosystems are those particles, which display increased solubility either through specialized coatings or through an ability to interact with water column constituents such as natural organic matter (NOM). Previous research has indicated that grazing zooplankton (Daphnia magna) are able to ingest lipid-coated single-walled carbon nanotubes (SWNTs) from the water column during their normal feeding behavior (Roberts et al., 2007). Acute mortality was observed only at high concentrations (>5mg/L). In this research NOM was used in place of a surfactant to stabilize suspensions. Water chemistry (ionic strength, hardness, and pH) has been shown to alter the behavior of NOM in natural systems. We hypothesized that these same variables may also affect the toxicity of multi-walled carbon nanotubes (MWNT) stabilized in NOM. The purpose of this research was to examine the potential for sublethal effects to occur following exposure to multi-walled carbon nanotubes suspended in NOM and to determine whether those effects vary with pH alterations.

  15. Tunneling phenomena in aligned multi-walled carbon nanotube sheets: conductivity and Raman correlations

    NASA Astrophysics Data System (ADS)

    del Corro, E.; Castillo-Martínez, E.; Taravillo, M.; Baonza, V. G.

    2014-12-01

    We performed simultaneous Raman spectroscopy and electrical conductivity measurements on self-standing aligned multi-walled carbon nanotubes sheets at varying inter-tube distances. A sapphire anvil cell is used here to modulate the inter-tube distance and promote the subsequent electronic tunneling phenomena. We observe a singular correlation between the intensity of the so called defect bands of carbon materials and their conductivity. This indicates that the conditions of the resonant processes that originate these bands are modified by the tunneling phenomena. Such an issue has never been reported before and has potential technological applications. Additionally, the provided AFM images evidence the debundling of the carbon nanotubes that had been described to occur after small compression.

  16. 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.

  17. Reinforcement of hydrogenated carboxylated nitrile-butadiene rubber by multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lu, Lan; Zhai, Yinghao; Zhang, Yong; Ong, Christopher; Guo, Sharon

    2008-12-01

    Hydrogenated carboxylated acrylonitrile-butadiene rubber (HXNBR) and multi-walled carbon nanotubes (MWCNT) composites were prepared. The dispersion of MWCNT in HXNBR matrix was evaluated by field emission scanning electron microscopy. HXNBR/MWCNT composite had shorter scorch time and optimum curing time compared with that of unfilled HXNBR. The tensile strength and modulus of HXNBR/MWCNT composites increased with increasing MWCNT content. Mooney-Rivlin equation was used to describe the stress-strain behavior of unfilled HXNBR and the strain amplification factor was taken into account for HXNBR/MWCNT composites. The Mullins effect and dynamic mechanical properties of HXNBR/MWCNT composite were also investigated.

  18. Preparation and Properties of Polyphenylene Sulfide/Multi-walled Carbon Nanotube Composites

    NASA Astrophysics Data System (ADS)

    Jiang, Zhenyu; Buchanan, Saul; McCool, Rauri; Hornsby, Peter; Murphy, Adrian

    2011-05-01

    Polyphenylene sulphide (PPS)/multi-walled carbon nanotube (MWCNT) composites were prepared using a melt-blending procedure combining centrifugal pre-mixing and twin-screw extrusion. A homogeneous dispersion of MWCNTs throughout the matrix was revealed by scanning electron microscopy for the nanocomposites with MWCNT contents ranging from 0.5 to 8.0 wt%. The presence of the MWCNTs showed both promotion and retardation effects on the crystallization of PPS. The competition between these two effects results in an unusual change of the degree of crystallinity with increasing MWCNT content. The mechanical properties of PPS were markedly enhanced by the incorporation of MWCNTs.

  19. Fabrication of superhydrophobic surfaces with poly(furfuryl alcohol)/multi-walled carbon nanotubes composites

    NASA Astrophysics Data System (ADS)

    Men, Xue-Hu; Zhang, Zhao-Zhu; Song, Hao-Jie; Wang, Kun; Jiang, Wei

    2008-02-01

    Superhydrophobic films of poly(furfuryl alcohol)/multi-walled carbon nanotubes (PFA/MWNTs) composites have been obtained by using fluorocarbon-modified MWNTs (MWNT-OOCC 7F 15), PFA, and PTFE with a simple preparation method. The prepared films showed both high contact angle and small sliding angle for water droplets. The chemical compositions and microstructures of the resultant film surfaces were also investigated by means of infrared spectroscopy, X-ray photoelectron spectroscopy, and field emission scanning electron microscope, respectively. Both the formed multiscale roughness structures and the lower surface energy play an important role in creating the superhydrophobic surfaces of PFA/MWNTs composites.

  20. Spectrophotometric Detection of Rhodamine B after Separation-Enrichment by Using Multi-walled Carbon Nanotubes.

    PubMed

    Unsal, Yunus Emre; Soylak, Mustafa; Tuzen, Mustafa

    2014-01-01

    A new, simple UV-Vis spectrophotometric method for the separation-preconcentration and determination of rhodamine B based on its adsorption onto multi-walled carbon nanotubes has been described. The effects of parameters for the quantitative recoveries of rhodamine B, including pH, flow, sample volumes, etc., were optimized. Matrix effects of concomitant ions or other dyes were also examined. The preconcentration factor and LOD were calculated as 125 and 0.80 μg/L, respectively. The procedure was applied to the spectrophotometric detection of rhodamine B in a soft drink, dialysis water, textile industry wastewater, and nail polish samples.

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

    PubMed

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

    2017-04-21

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

  3. 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.

  4. Dielectric characterization of multi-walled carbon nanotube nanocomposites as a function of ultraviolet exposure at microwave frequency

    NASA Astrophysics Data System (ADS)

    Orloff, Nathan; Long, Christian J.; Twedt, Kevin; Lam, Thomas; McClelland, Jabez; Obrzut, Jan; Liddle, J. Alexander

    2014-03-01

    We investigate multi-walled carbon nanotube epoxy composites as a function of ultraviolet exposure. As the epoxy is etched away from the composite, we found that the multi-walled carbon nanotubes form a thin conducting layer on the surface. We then characterize the multi-walled carbon nanotube composites by atomic force microscopy, lithium ion microscopy, and microwave cavity perturbation at each value of ultraviolet exposure. We perform our measurements on a set of neat samples made from a stoichiometric mixture bisphenol A epoxy resin and another set that contains a mass fraction of 3.5% multi-walled carbon nanotubes. The samples were then exposed to ultraviolet radiation to etch the surface for different durations of time. At the 7.31 GHz, we measured the permittivity and loss tangent of the unexposed epoxy to be ɛ = 2.93 +/-0.11 and tan δ = 0.029 +/-0.002, respectively. The unexposed epoxy with a mass fraction of 3.5% multi-walled carbon nanotubes had a permittivity of ɛ = 8.01 +/-0.48 and loss tangent of tan δ = 0.144 +/-0.011.

  5. One-pot, efficient functionalization of multi-walled carbon nanotubes with diamines by microwave method

    NASA Astrophysics Data System (ADS)

    Amiri, A.; Maghrebi, M.; Baniadam, M.; Zeinali Heris, S.

    2011-09-01

    Diamines are known to act as a medium to bind miscellaneous compounds to carbon nanotubes (CNT). However, they are commonly applied in a tedious manner. Here, multi-walled carbon nanotubes (MWCNTs) were functionalized by a series of diamine molecules (ethylenediamine, 1,6-hexamethylenediamine and 1,4-diaminobenzen) in a one-pot, rapid microwave-assisted method. Surface functionality groups and morphology of MWCNTs were analyzed by infrared spectroscopy, thermogravimetric analysis, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results consistently confirmed the formation of diamines functionalities on MWCNTs, while the structure of MWCNT has remained relatively intact. This simple and efficient process may play an important role for realizing miscellaneous functionalization of CNTs.

  6. Synthesis and enhanced photocatalytic activity of tin oxide nanoparticles coated on multi-walled carbon nanotube

    SciTech Connect

    Wang, Ning; Xu, Jiaoxing; Guan, Lunhui

    2011-09-15

    Highlights: {yields} SnO{sub 2} nanoparticles were uniformly deposited on carbon nanotubes. {yields} MWNT@SnO{sub 2} showed excellent photocatalytic activity. {yields} The quenched PL proved the existence of electron transfer between SnO{sub 2} and MWNT. -- Abstract: A nanocomposite of SnO{sub 2} nanoparticles coated on multi-walled carbon nanotube (MWNT@SnO{sub 2}) was synthesized and characterized by thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, nitrogen physisorption measurements, photoluminescence. The results show that the SnO{sub 2} nanoparticles with a narrow size of 4 nm are uniformly deposited on MWNT. The photocatalytic activity of the nanocomposite was studied using methyl orange as a model organic pollutant. MWNT@SnO{sub 2} exhibits much higher photocatalytic activity than that of commercial TiO{sub 2} (P-25). The promotion is mainly contributed from electron transfer between SnO{sub 2} and MWNT.

  7. Enhancement of polymer luminescence by excitation-energy transfer from multi-walled carbon nanotubes.

    PubMed

    Henley, Simon J; Hatton, Ross A; Chen, Guan Y; Gao, Chao; Zeng, Hailin; Kroto, Harold W; Silva, S Ravi P

    2007-11-01

    Carbon nanotubes have been shown to efficiently quench luminescence from conjugated polymers when incorporated in a composite. However, shown here is an up to 100-fold increase in the visible photoluminescence signal from fluorescent chromophores in nylon 10,10 by incorporating multi-walled carbon nanotubes (MWCNTs). Using 325- and 488-nm excitation the optical absorption by MWCNTs embedded within the polymer matrix is demonstrated, followed by efficient excitation-energy transfer to emissive chromophores intrinsic to the polymer but only when the MWCNTs are acid functionalized. Furthermore, the MWCNTs are shown to significantly retard photobleaching of fluorescent centers in the nylon composites. These remarkable properties greatly advance the prospects of utilizing MWCNTs in organic solar cells and electroluminecent devices to improve performance.

  8. 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...

  9. 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...

  10. Study on the infrared property of polyaniline/multi-wall carbon nanotube composite.

    PubMed

    Ju, Changbin; Wang, Yongsheng; He, Dawei; Gao, Qi; Gao, Lei; Fu, Ming

    2012-08-01

    Composites of polyaniline (PANI) and multi-wall carbon nanotube (MWNT) were synthesized by in situ polymerization with different MWNT content. The composites were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The SEM photos indicated that a mass of MWNT was enchased into PANI matrix when the content of MWNT was low. With the MWNT content increases, the surface of MWNT was covered with PANI and formed the core-shell structure. From the FT-IR spectroscopy of the composites, it can be confirmed that there was interaction between PANI and multi-wall carbon nanotube. The composites had better thermal stability than pure PANI. Infrared emission property of the composites was analyzed by an IR-II infrared emissivity instrument and an infrared camera. It was found that infrared emission of the composites was lower than pure PANI in all wavelength range and infrared emissivity value was related to the content of MWNT in the composites.

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

    PubMed

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

    2017-02-05

    The aqueous phase electrochemical degradation of nalidixic acid (NAL) is studied in this work, using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) as instrumental techniques. The promotional effect of multi-walled carbon nanotubes (MWCNT) on the performance of glassy carbon electrodes is demonstrated, being observed that these materials catalyze the NAL reduction. The effect of surface functional groups on MWCNT -MWCNT-COOH and MWCNT-NH2-was also studied. The modification of glassy carbon electrode (GCE) with MWCNT leads to an improved performance for NAL reduction following the order of MWCNT>MWCNT-NH2>MWCNT-COOH. The best behavior at MWCNT-GCE is mainly due to both the increased electrode active area and the enhanced MWCNT adsorption properties. The NAL degradation was carried out under optimal conditions (pH=5.0, deposition time=20s and volume of MWCNT=10μL) using MWCNT-GCE obtaining an irreversible reduction of NAL to less toxic products. Paramaters as the number of DPV cycles and the volume/area (V/A) ratio were optimized for maximize pollutant degradation. It was observed that after 15 DPV scans and V/A=8, a complete reduction was obtained, obtaining two sub-products identified by liquid chromatography-mass spectrometry (LC-MS).

  12. 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.

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

    PubMed

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

    2017-02-01

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

  14. Surfactant dispersed multi-walled carbon nanotube/polyetherimide nanocomposite membrane

    NASA Astrophysics Data System (ADS)

    Goh, P. S.; Ng, B. C.; Ismail, A. F.; Aziz, M.; Sanip, S. M.

    2010-12-01

    Carbon nanotube based nanocomposite membranes have been fabricated through solution casting by embedding multi-walled carbon nanotubes (MWCNTs) within polyetherimide (PEI) polymer host matrix. In order to achieve fine dispersion of nanotubes and facilitate strong interfacial adhesion with the polymer matrix, the nanotubes were first treated with surfactants of different charges, namely anionic sodium dodecyl chloride, cationic cetyl trimethyl ammonium chloride and non-ionic Triton X100, prior to the dispersion in the PEI dope solution. Dispersion of MWCNTs in N-methyl-2-pyrrolidone solvent showed that the agglomeration and entanglement of the nanotubes were greatly reduced upon the addition of Triton X100. Scanning electron microscopy and atomic force microscopy examination has evidenced the compatibility of Triton X100 dispersed MWCNTs with the polymer matrix in which a promising dispersion and adhesion has been observed at the MWCNT-PEI interface. The increase in both thermal stability and mechanical strength of the resulting Triton X100 dispersed MWCNT/PEI nanocomposite indicated the improved interaction between MWCNTs and PEI. This study demonstrated the role of Triton X100 in facilitating the synergetic effects of MWCNTs and PEI where the resulting composite membrane is anticipated to have potential application in membrane based gas separation.

  15. Physiological Effects of Single- and Multi-Walled Carbon Nanotubes on Rice Seedlings.

    PubMed

    Zhang, Hao; Yue, Mengxia; Zheng, Xueke; Xie, Chengshen; Zhou, Hong; Li, Lijia

    2017-10-01

    In this paper, single-walled carbon nano- tubes (SWCNTs) and multi-walled carbon nano- tubes (MWCNTs) were found to accelerate leaf growth and development of rice seedlings at a low concentration (20 mg/L), accompanied with the increased chlorophyll content and net photosynthetic rate (PN). Quantitative real-time polymerase chain reaction results indicated that both SWCNTs and MWCNTs significantly increased expression of genes associated with chloroplast development and cell sizes. Further analysis revealed that the abscisic acid content decreased and the gibberellin content increased while the content of [Formula: see text] and H2O2 was slightly elevated and the activities of antioxidative enzymes (SOD, EC 1.15.1.1, and POD, EC 1.11.1.7) were differently modulated after treatment with the carbon nanotube (CNT). These results suggest a possible link between reactive oxygen species and plant hormones under CNTs treatment to promote rice seedlings growth.

  16. 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...

  17. Multi-walled Carbon Nanotubes Reduce Toxicity of Diphenhydramine to Ceriodaphnia dubia in Water and Sediment Exposures.

    PubMed

    Myer, Mark H; Black, Marsha C

    2017-08-09

    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.

  18. 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

  19. 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

  20. Elucidation mechanism of different biological responses to multi-walled carbon nanotubes using four cell lines

    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

    We examined differences in cellular responses to multi-walled carbon nanotubes (MWCNTs) using malignant pleural mesothelioma cells (MESO-1), bronchial epithelial cells (BEAS-2B), neuroblastoma cells (IMR-32), and monoblastic cells (THP-1), before and after differentiation. MESO-1, BEAS-2B and differentiated THP-1 cells actively endocytosed MWCNTs, resulting in cytotoxicity with lysosomal injury. However, cytotoxicity did not occur in IMR-32 or undifferentiated THP-1 cells. Both differentiated and undifferentiated THP-1 cells exhibited an inflammatory response. Carbon blacks were endocytosed by the same cell types without lysosomal damage and caused cytokine secretion, but they did not cause cytotoxicity. These results indicate that the cytotoxicity of MWCNTs requires not only cellular uptake but also lysosomal injury. Furthermore, it seems that membrane permeability or cytokine secretion without cytotoxicity results from several active mechanisms. Clarification of the cellular recognition mechanism for MWCNTs is important for developing safer MWCNTs. PMID:22267932

  1. Synthesis and Characterization of Multi Wall Carbon Nanotubes (MWCNT) Reinforced Sintered Magnesium Matrix Composites

    NASA Astrophysics Data System (ADS)

    Vijaya Bhaskar, S.; Rajmohan, T.; Palanikumar, K.; Bharath Ganesh Kumar, B.

    2016-04-01

    Metal matrix composites (MMCs) reinforced with ceramic nano particles (less than 100 nm), termed as metal matrix nano composites (MMNCs), can overcome those disadvantages associated with the conventional MMCs. MMCs containing carbon nanotubes are being developed and projected for diverse applications in various fields of engineering like automotive, avionic, electronic and bio-medical sectors. The present investigation deals with the synthesis and characterization of hybrid magnesium matrix reinforced with various different wt% (0-0.45) of multi wall carbon nano tubes (MWCNT) and micro SiC particles prepared through powder metallurgy route. Microstructure and mechanical properties such as micro hardness and density of the composites were examined. Microstructure of MMNCs have been investigated by scanning electron microscope, X-ray diffraction and energy dispersive X-ray spectroscopy (EDS) for better observation of dispersion of reinforcement. The results indicated that the increase in wt% of MWCNT improves the mechanical properties of the composite.

  2. 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

  3. 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.

  4. Single-walled and multi-walled carbon nanotubes based drug delivery system: Cancer therapy: A review.

    PubMed

    Dineshkumar, B; Krishnakumar, K; Bhatt, A R; Paul, D; Cherian, J; John, A; Suresh, S

    2015-01-01

    Carbon nanotubes (CNTs) are advanced nano-carrier for delivery of drugs especially anti-cancer drugs. In the field of CNT-based drug delivery system, both single-walled carbon nanotubes (SWCNTs) and multi-walled nanotubes (MWCNTs) can be used for targeting anticancer drugs in tissues and organs, where the high therapeutic effect is necessary. Benefits of the carbon nanotubes (CNTs) in drug delivery systems are; avoiding solvent usage and reducing the side effects. Therefore, the present review article described about achievement of SWCNTs and MWCNTs to deliver the anticancer drugs with different cancerous cell lines.

  5. Multi-walled carbon nanotubes affect drug transport across cell membrane in rat astrocytes

    NASA Astrophysics Data System (ADS)

    Chen, Xiao; Schluesener, Hermann J.

    2010-03-01

    The impact of carbon nanotubes on the cell membrane is an aspect of particular importance and interest in the study of carbon nanotubes' interactions with living systems. One of the many functions of the cell membrane is to execute substance transport into and out of the cell. We investigated the influence of multi-walled carbon nanotubes (MWCNTs) on the transport of several compounds across in the cell membrane of rat astrocytes using flow cytometry. These compounds are fluorescein diacetate, carboxyfluorescein diacetate, rhodamine 123 and doxorubicin, which are prosubstrate/substrates of multidrug transporter proteins. Results showed that MWCNTs significantly inhibited cellular uptake of doxorubicin but not the other drugs and the mode of loading made a significant difference in doxorubicin uptake. Retention of fluorescein, carboxyfluorescein and rhodamine 123 was remarkably higher in MWCNT-exposed cells after an efflux period. A kinetics study also demonstrated slower efflux of intracellular fluorescein and rhodamine 123. Data presented in this paper suggest that MWCNTs could affect drug transport across cell membranes. The implications of the findings are discussed.

  6. 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.

  7. Functionalized Multi-Walled Carbon Nanotube Paper for Monitoring Chemical Vapors.

    PubMed

    Slobodian, P; Riha, P; Olejnik, R; Saha, P

    2015-05-01

    The multi-walled carbon nanotube paper is prepared by vacuum filtration of pure nanotubes and their functionalized forms prepared by KMnO4 and H2O2 oxidation or by grafting with Poly(methyl methacrylate) (PMMA) and polypyrrole to form sensory nanotubes layer for detection of volatile organic compounds in air. The selected compounds for experimentation (acetone, diethyl ether, isopentane, methanol, tetrahydrofuran) have different polarities and volume fractions of saturated vapors. The sensing is measured by electrical resistance of the paper, which increases when exposed to vapors. A reversible reaction is observed when the paper is removed from the vapors. The functionalized nanotubes differ in their sensitivity to selected organics solvents. For example, KMnO4 oxidized paper has differentiated response to all used vapors, so the measured data may indicate clearly the type of the vapor. On the other hand, the MWCNT/PMMA composite has nearly the same response to acetone, diethyl ether and tetrahydrofuran and different response to isopentane and methanol. The investigation can lead to construction of sensory unit which could be capable of detecting and identifying different vapors in the air.

  8. 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

  9. Self-assembly formation of multi-walled carbon nanotubes on gold surfaces.

    PubMed

    Lin, Jarrn-Horng; Chen, Ching-Shiun; Rümmeli, Mark H; Zeng, Zhi-Yan

    2010-12-01

    We report on the observation of self-assembled carbon nanostructures on a standard transmission electron microscopy (TEM) Au substrate formed via thermal chemical vapor deposition. Multi-walled carbon nanotubes (MWNTs) and other carbon nanostructures (CNs), such as carbon nanofibers and carbon nanoparticles (NPs), could be fabricated through structural transformation of metastable carbon layers on the Au surface during 800-850 °C with the thermal decomposition of ethylene. At these temperatures, we found that Au NPs will form immediately through the structural transformation of the Au grid surface in helium atmosphere. The Au NPs work as active centers to trigger the decomposition of ethylene into carbon atoms, which form metastable carbon layers or amorphous carbon nanobugs, and then form CNs via self-assembling. The growth of CNs was characterized by field-emission scanning electron microscopy (SEM), high-resolution TEM and RAMAN spectroscopy. The transformation of amorphous carbon nanobugs by electron beam irradiation is also recorded by in situ monitoring of TEM.

  10. 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.

  11. Kinetics and thermodynamic study of aniline adsorption by multi-walled carbon nanotubes from aqueous solution.

    PubMed

    Al-Johani, Hind; Abdel Salam, Mohamed

    2011-08-15

    Multi-walled carbon nanotubes (MWCNTs) were used in the adsorptive removal of aniline, an organic pollutant, from an aqueous solution. It was found that carbon nanotubes with a higher specific surface area adsorbed and removed more aniline from an aqueous solution. The adsorption was dependent on factors, such as MWCNTs dosage, contact time, aniline concentration, solution pH and temperature. The adsorption study was analyzed kinetically, and the results revealed that the adsorption followed pseudo-second order kinetics with good correlation coefficients. In addition, it was found that the adsorption of aniline occurred in two consecutive steps, including the slow intra-particle diffusion of aniline molecules through the nanotubes. Various thermodynamic parameters, including the Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°), were calculated. The results indicated that the spontaneity of the adsorption, exothermic nature of the adsorption and the decrease in the randomness reported as ΔG°, ΔH° and ΔS°, respectively, were all negative.

  12. The functionalization and characterization of multi-walled carbon nanotubes (MWCNTs)

    SciTech Connect

    Abdullah, Mohd Pauzi; Zulkepli, Siti Aminah

    2015-09-25

    Functionalization is the process of introducing chemical functional groups on the surface of the material. In this study, a multi-walled carbon nanotube (MWCNTs) was functionalized by oxidation treatment using concentrated nitric acid. The functionalized and pristine MWCNTs were analyzed by using Fourier Transform Infrared Spectroscopy (FT-IR) and X-Ray Diffraction (XRD). The XRD patterns exhibit the graphitic properties for all samples. Besides, the XRD results also demonstrate that the percent of crystallinity of MWCNTs increases as the duration of acid treatment increases. The percent of crystallinity increases from 66% to 80% when the pristine MWCNT treated for 12 hours with additional 12 hours reflux process with nitric acid. The IR spectrum for the 12 hours-treated MWCNTs shows the formation of carboxyl functional group. Additional 12 hours reflux process with nitric acid on the 12 hours-treated MWCNTs have shown the loss of existing carboxyl group and only hydroxyl group formed.

  13. Facile synthesis of stable superhydrophobic nanocomposite based on multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Mokarian, Zahra; Rasuli, Reza; Abedini, Yousefali

    2016-04-01

    A facile approach to fabricate a stable superhydrophobic composite comprising multi-walled carbon nanotubes and silicone rubber has been reported. Contact angle of de-ionized water droplets on the prepared surface was measured with the value of near 159°; while water droplets easily rolled off and bounced on it. Surface free energy of the superhydrophobic coating was examined by three methods about 26 mJ/m2. The prepared film shows good stability under high stress conditions such as ultraviolet exposure, heating, pencil hardness test, attacking with different pH value and ionic-strength solutions. In addition, remarkable stability of the coating was observed after soaking in condensed hydrochloric acid, 5 wt.% NaCl aqueous solution, boiling water and tape test.

  14. 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.

  15. Rheological and mechanical study of regenerated cellulose/multi-walled carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Shao, Wei; Wang, Shuxia; Liu, Hui; Wu, Jimin; Huang, Min; Ma, Wenjing; Huang, Chaobo

    2016-09-01

    Regenerated cellulose (RC)-based composites reinforced with multi-walled carbon nanotubes (MWCNTs) were prepared by a facile casting method. The morphology and microstructure of the fabricated composites were characterized using transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. Thermogravimetry and derivative thermogravimetric analysis were conducted to investigate the effect of MWCNTs on the thermal behaviors of the RC. The results showed that the introduction of MWCNTs enhanced the thermal stability of the RC. Moreover, the effect of the dispersion state of MWCNTs in microcrystalline cellulose/ZnCl2 solutions with varying MWCNT loadings was studied by rheological tests. The mechanical properties of composite films were remarkably improved compared to those of pure RC film. Specifically, the composite film containing 3 wt% of MWCNTs exhibits a 123% enhancement in tensile strength and a 163% enhancement in the Young’s modulus compared with the pure RC film.

  16. Simple quantification of surface carboxylic acids on chemically oxidized multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Gong, Hyejin; Kim, Seong-Taek; Lee, Jong Doo; Yim, Sanggyu

    2013-02-01

    The surface of multi-walled carbon nanotube (MWCNT) was chemically oxidized using nitric acid and sulfuric-nitric acid mixtures. Thermogravimetric analysis, transmission electron microscopy and infrared spectroscopy revealed that the use of acid mixtures led to higher degree of oxidation. More quantitative identification of surface carboxylic acids was carried out using X-ray photoelectron spectroscopy (XPS) and acid-base titration. However, these techniques are costly and require very long analysis times to promptly respond to the extent of the reaction. We propose a much simpler method using pH measurements and pre-determined pKa value in order to estimate the concentration of carboxylic acids on the oxidized MWCNT surfaces. The results from this technique were consistent with those obtained from XPS and titration, and it is expected that this simple quantification method can provide a cheap and fast way to monitor and control the oxidation reaction of MWCNT.

  17. High temperature electromagnetic and microwave absorbing properties of polyimide/multi-walled carbon nanotubes nancomposites

    NASA Astrophysics Data System (ADS)

    Wang, Hongyu; Zhu, Dongmei; Zhou, Wancheng; Luo, Fa

    2015-07-01

    Multi-walled carbon nanotubes (MWCNTs) were introduced into polyimide matrix to fabricate high temperature microwave absorbing materials. The flexural strength can reach 125 MPa with 2 wt% MWCNTs, and the flexural strength decreases with increasing the filler content due to the filler reinforcement. The complex permittivity of the nanocomposite increases with increasing the temperature owing to shorten the relaxation time and enhance the electrical conductivity at elevated temperature. When the content of absorbent is 5%, the -10 dB absorption bandwidth could reach 1.3 GHz, with the thickness of 2.1 mm, while the bandwidth below -10 dB is 2.04 GHz with the thickness of 1.7 mm at 373 K.

  18. Mechanical characterization and morphology of polylactic acid /liquid natural rubber filled with multi walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ali, Adilah Mat; Ahmad, Sahrim Hj.

    2013-11-01

    In this paper the polymer nanocomposite of multi-walled carbon nanotubes (MWCNTs) nanoparticles was incorporated with polylactic acid (PLA) and liquid natural rubber (LNR) as compatibilizer were prepared via melt blending method. The effect of MWCNTs loading on the tensile and impact properties of nanocomposites was investigated. The result has shown that the sample with 3.5 wt % of MWCNTs exhibited higher tensile strength, Young's modulus and impact strength. The elongation at break decreased with increasing percentage of MWCNTs. The SEM micrographs confirmed the effect of good dispersion of MWCNTs and their interfacial bonding in PLA/LNR composites. The improved dispersion of MWCNTs can be obtained due to altered interparticle interactions, MWCNTs-MWCNTs and MWCNTs-matrix networks are well combined to generate the synergistic effect of the system as shown by SEM micrographs which is improved the properties significantly.

  19. Synthesis of ZnO coated multi-walled carbon nanotubes and their antibacterial activities.

    PubMed

    Sui, Minghao; Zhang, Lingdian; Sheng, Li; Huang, Shuhang; She, Lei

    2013-05-01

    ZnO coated multi-walled carbon nanotubes (ZnO/MWCNTs) were prepared and evaluated for their application potentials as an antimicrobial material for simultaneous concentrating and inactivating pathogenic bacteria. X-ray energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectra (XPS) were used to characterize the ZnO/MWCNTs. Escherichia coli (E. coli) was employed as the target bacterium. Comparing with the raw and the purified MWCNTs (r-MWCNTs and p-MWCNTs), which have been reported to possess antibacterial activity towards E. coli, ZnO/MWCNTs exhibited stronger antibacterial ability. The deposited ZnO was suggested to play an important role in the bactericidal action of ZnO/MWCNTs, while, the r-MWCNTs and p-MWCNTs served as more like adsorbing materials for E. coli.

  20. 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.

  1. Radial Corrugations of Multi-Walled Carbon Nanotubes Driven by Inter-Wall Nonbonding Interactions.

    PubMed

    Huang, Xu; Liang, Wentao; Zhang, Sulin

    2011-12-01

    We perform large-scale quasi-continuum simulations to determine the stable cross-sectional configurations of free-standing multi-walled carbon nanotubes (MWCNTs). We show that at an inter-wall spacing larger than the equilibrium distance set by the inter-wall van der Waals (vdW) interactions, the initial circular cross-sections of the MWCNTs are transformed into symmetric polygonal shapes or asymmetric water-drop-like shapes. Our simulations also show that removing several innermost walls causes even more drastic cross-sectional polygonization of the MWCNTs. The predicted cross-sectional configurations agree with prior experimental observations. We attribute the radial corrugations to the compressive stresses induced by the excessive inter-wall vdW energy release of the MWCNTs. The stable cross-sectional configurations provide fundamental guidance to the design of single MWCNT-based devices and shed lights on the mechanical control of electrical properties.

  2. 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.

  3. Development of micro engine oil condition sensor using multi-wall carbon nanotube films

    NASA Astrophysics Data System (ADS)

    Na, Dae Seok; Jung-Ho Pak, James; Kyeong Kim, Jai

    2007-03-01

    A new interdigit-type micro oil condition sensor was designed and fabricated for monitoring the deterioration of lubricating and insulating oils. The designed sensor operates based on the change of the dielectric constant and electrical conductivity. In order to improve sensor performance, an oil condition sensor was fabricated using MEMS technology and multi-wall carbon nanotube film. The experiment was performed with automobile engine oils with the same brand and quality so as to ensure measurement reliability. Capacitance changes were measured according to increasing mileage and the sensors' performance was improved. These results show that the proposed sensor could measure the degree of oil deterioration with a high sensitivity and it is applicable to other lubricating systems as well as insulating systems.

  4. Functionalization of multi-walled carbon nanotubes via surface unpaired electrons.

    PubMed

    Zhang, Haijiao; Guo, Huijiao; Deng, Xiaoyong; Gu, Ping; Chen, Zhiwen; Jiao, Zheng

    2010-02-26

    The unpaired electrons on multi-walled carbon nanotubes (MWNTs) treated by nitric-sulfuric mixed acid were detected and characterized by electron spin resonance (ESR). Through reacting with these unpaired electrons, highly soluble acrylamide-grafted MWNTs were successfully prepared and characterized by ESR, FT-IR, UV-vis and atomic force microscopy (AFM), etc. The results indicate that MWNTs could generate more unpaired electrons with longer mixed-acid treatment time and could be well functionalized by acrylamide. By AFM analysis, a 'net' structure was formed on MWNTs after grafting with acrylamide. This new method has some obvious advantages of mild reaction conditions and convenient operation, etc. Furthermore, the grafting of MWNTs may have great potential for biomedical applications in drug delivery and regenerative medicine owing to their excellent networks.

  5. Functionalization of multi-walled carbon nanotubes via surface unpaired electrons

    NASA Astrophysics Data System (ADS)

    Zhang, Haijiao; Guo, Huijiao; Deng, Xiaoyong; Gu, Ping; Chen, Zhiwen; Jiao, Zheng

    2010-02-01

    The unpaired electrons on multi-walled carbon nanotubes (MWNTs) treated by nitric-sulfuric mixed acid were detected and characterized by electron spin resonance (ESR). Through reacting with these unpaired electrons, highly soluble acrylamide-grafted MWNTs were successfully prepared and characterized by ESR, FT-IR, UV-vis and atomic force microscopy (AFM), etc. The results indicate that MWNTs could generate more unpaired electrons with longer mixed-acid treatment time and could be well functionalized by acrylamide. By AFM analysis, a 'net' structure was formed on MWNTs after grafting with acrylamide. This new method has some obvious advantages of mild reaction conditions and convenient operation, etc. Furthermore, the grafting of MWNTs may have great potential for biomedical applications in drug delivery and regenerative medicine owing to their excellent networks.

  6. Investigation of activity and stability of papain by adsorption on multi-wall carbon nanotubes.

    PubMed

    Homaei, Ahmad; Samari, Fayezeh

    2017-02-14

    Papain was non-covalently immobilized on multi-walled carbon nanotubes (MWCNTs). Its stabilities and catalytic activity for casein degradation were comprehensively investigated. Compared to free papain, the nano-enzyme exhibited significantly improved thermal, pH and recycling stability. Comparisons of the kinetic parameters between free papain and the heterogeneous enzyme revealed that the Km value of the immobilized papain experienced a slight increase, which suggested that the MWCNTs did not significantly hinder papain's access to substrate or release of product. This feature is beneficial to the industrial applications because of its potential to be easily separated from the end product at the end of the reaction, reuse for multiple times and allow the development of multiple enzyme reaction system.

  7. Oxidative treatment, dispersion effect, and simulation of multi-walled carbon nanotubes in aqueous solution

    NASA Astrophysics Data System (ADS)

    Song, Kai; Guo, Li-Quan; Chen, Hui

    2017-01-01

    In the present work, the multi-walled carbon nanotubes (MWCNTs) were modified by the treatment with concentrated nitric and sulfuric acid mixture (3: 1 vol/vol). The obtained material was characterized by X-ray diffraction (XRD). The effect of two surfactants, methylcellulose (MC) and cetyltrimethylammonium bromide (CTAB) on dispersing of MWCNTs in aqueous solution was monitored by UV-Vis spectroscopy and transmission electron microscopy (TEM). Also, the dispersing effect of the surfactants was simulated by three-dimensional Monte Carlo method. The results showed that the oxidative treatment leads to purification of the neat MWCNTs, and directly improved their dispersing. The mixture containing both MC and CTAB surfactants has better dispersing effect than individual surfactants. The optimum concentration ratio of MC, CTAB, and MWCNTs was 2: 3: 1. In the simulation model, MWCNTs were dispersed randomly. The simulation results may be helpful for the further research on mechanical and electrical properties of composites reinforced with MWCNTs.

  8. Fast functionalization of multi-walled carbon nanotubes by an atmospheric pressure plasma jet.

    PubMed

    Kolacyak, Daniel; Ihde, Jörg; Merten, Christian; Hartwig, Andreas; Lommatzsch, Uwe

    2011-07-01

    The afterglow of an atmospheric pressure plasma has been used for the fast oxidative functionalization of multi-walled carbon nanotubes (MWCNTs). Scanning electron microscopy and Raman spectroscopy demonstrate that the MWCNT morphology is mostly preserved when the MWCNTs are dispersed in a solvent and injected as a spray into the plasma. Contact angle measurements show that this approach enhances the wettability of MWCNTs and reduces their sedimentation in an aqueous dispersion. X-ray photoelectron spectroscopy, IR spectroscopy, and electrokinetic measurements show that oxygen plasma incorporates about 6.6 at.% of oxygen and creates mainly hydroxyl and carboxyl functional groups on the MWCNT surface. The typical effective treatment time is estimated to be in the range of milliseconds. The approach is ideally suited for combination with the industrial gas phase CVD synthesis of MWCNTs.

  9. DNA methylation changes in human lung epithelia cells exposed to multi-walled carbon nanotubes.

    PubMed

    Sierra, Marta I; Rubio, Laura; Bayón, Gustavo F; Cobo, Isabel; Menendez, Pablo; Morales, Paula; Mangas, Cristina; Urdinguio, Rocio G; Lopez, Virginia; Valdes, Adolfo; Vales, Gerard; Marcos, Ricard; Torrecillas, Ramon; Fernández, Agustin F; Fraga, Mario F

    2017-09-13

    Humans are increasingly exposed to nanoparticles and, although many of their physiological effects have been described, the molecular mechanisms underlying them are still largely unknown. The present study aimed to determine the possible role of certain epigenetic mechanisms in the cellular response of human lung epithelial cells that are triggered by long-term exposure to titanium dioxide nanoparticles (TiO2NPs) and multi-walled carbon nanotubes (MWCNTs). The results showed that exposure to TiO2NPs had only minor effects on genome-wide DNA methylation. However, we identified 755 CpG sites showing consistent DNA hypomethylation in cells exposed to MWCNTs. These sites were mainly located at low density CpG regions and enhancers, and very frequently on the X chromosome. Our results thus suggest that long-term MWCNT exposure may have important effects on the epigenome.

  10. Energy Spread of Field Emission Electrons from Single Pentagons in Individual Multi-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Fujieda, Tadashi; Okai, Makoto; Tokumoto, Hiroshi

    2008-04-01

    We investigated the dependence of tip radius on the field emission energy spread of electrons emitted from clean single pentagons in individual multi-walled carbon nanotubes (MWNTs) in a wide range of total emission currents (10-2000 nA). We found that the full width at half maximum of the field emission energy distribution decreases in inverse proportion to the involution of the radius of curvature at a constant total emission current. This is because as the radius of curvature increases, the space between adjoining pentagons becomes wider, and therefore the stochastic Coulomb interactions between electrons emitted from adjoining pentagons become weaker. The full widths at half maximum of the field emission energy distributions of MWNTs with tip radii of 1.8-45.0 nm were 0.38-0.60 eV at a total emission current of 2000 nA.

  11. Multi walled carbon nanotube nanocomposites with biodegradable poly(butylene succinate) and their physical characteristics.

    PubMed

    Hong, M K; Ko, S W; Park, J H; Choi, H J; Kim, J H

    2011-06-01

    In order to examine the influence of multi walled carbon nanotube (MWNT) on physical properties of its biodegradable polymer nanocomposite, biodegradable poly(buthylene succinate) (PBS), which was synthesized from diols and dicarboxylic acids, and MWNT nanocomposites were prepared via a melt-mixing method using a co-rotating intermeshing twin screw extruder. Microstructure of the PBS/MWNT nanocomposites and MWNT were investigated via both scanning electron microscopy and transmission electron microscopy. Their rheological properties were also characterized via rotation and oscillation tests using a rotational rheometer with parallel-plate geometry. It was found that shear viscosity, storage modulus and loss modulus of the nanocomposites examined by a rotational rheometer increased with the MWNT content. Especially their sharp increase for MWNT content of ca. 2.0 wt% was observed, indicating its percolation threshold from the rheological viewpoint which was higher than its electrical percolation threshold (1.0 wt%).

  12. Development of multi-walled carbon nanotubes reinforced monetite bionanocomposite cements for orthopedic applications.

    PubMed

    Boroujeni, Nariman Mansoori; Zhou, Huan; Luchini, Timothy J F; Bhaduri, Sarit B

    2013-10-01

    In this study, we present results of our research on biodegradable monetite (DCPA, CaHPO4) cement with surface-modified multi-walled carbon nanotubes (mMWCNTs) as potential bone defect repair material. The cement pastes showed desirable handling properties and possessed a suitable setting time for use in surgical setting. The incorporation of mMWCNTs shortened the setting time of DCPA and increased the compressive strength of DCPA cement from 11.09±1.85 MPa to 21.56±2.47 MPa. The cytocompatibility of the materials was investigated in vitro using the preosteoblast cell line MC3T3-E1. An increase of cell numbers was observed on both DCPA and DCPA-mMWCNTs. Scanning electron microscopy (SEM) results also revealed an obvious cell growth on the surface of the cements. Based on these results, DCPA-mMWCNTs composite cements can be considered as potential bone defect repair materials.

  13. Biomimetic Synthesis of FePt Nanoparticles on Multi-Walled Carbon Nanotubes for Functional Nanomaterials

    NASA Astrophysics Data System (ADS)

    Wang, Li; Wang, Jiku; Li, Zhuang

    2013-02-01

    We present a facile green biomimetic synthesis of FePt nanoparticles (NPs) on the sidewalls of multi-walled carbon nanotubes (CNTs). A core-shell globular protein, ferritin (Fr), was bound onto Z-glycine N-succinimidyl ester (Z-Gly-OSu) modified CNTs and served as precursor to create FePt NPs at the core part of Fr. Biomimetic synthesis of FePt NPs was carried out by chemical reducing of Fe2+ and PtCl_{6}^{2-} ions that transferred into the core part of Fr molecules. The created one-dimensional CNT-FePt nanohybrids were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. The synthesized CNT-FePt nanohybrids show multi-properties of high water-solubility, ferromagnetism, and electrocatalytic activity.

  14. 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

    2017-03-23

    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.

  15. Gold nanoparticle decorated multi-walled carbon nanotubes as counter electrode for dye sensitized solar cells.

    PubMed

    Kaniyoor, Adarsh; Ramaprabhu, Sundara

    2012-11-01

    A novel counter electrode material for dye sensitized solar cells (DSSCs) composed of nanostructured Au particles decorated on functionalized multi-walled carbon nanotubes (f-MWNTs) is demonstrated for the first time. MWNTs synthesized by catalytic chemical vapor deposition technique are purified and functionalized by treating with concentrated acids. Au nanoparticles are decorated on f-MWNTs by a rapid and facile microwave assisted polyol reduction method. The materials are characterized by X-ray diffractometry, Fourier transform infra red spectroscopy and electron microscopy. The DSSC fabricated with Au/f-MWNTs based counter electrode shows enhanced power conversion efficiency (eta) of 4.9% under AM 1.5G simulated solar radiation. In comparison, the reference DSSCs fabricated with f-MWNTs and Pt counter electrodes show eta of 2.1% and 4.5%. This high performance of Au/f-MWNTs counter electrode is investigated using electrochemical impedance spectroscopy and cyclic voltammetry studies.

  16. Heat transfer characteristics of multi-walled carbon nanotubes suspension in a developing channel flow

    NASA Astrophysics Data System (ADS)

    Elnajjar, Emad; Haik, Yousef; Hamdan, Mohammad O.; Khashan, Saud

    2013-12-01

    The present study experimentally investigates the effect of multi wall carbon nanotubes (MWCNT) suspensions on the convective heat transfer coefficients. The MWCNT suspensions used in this study were prepared by dispersing MWCNTs in deionized water 0.25 wt% arab gum solution. The heat transfer characteristics were measured for thermally developing laminar flow in a finite length horizontal circular pipe under isothermal wall conditions. The study was conducted over a range of Reynolds number of 300-2,300, based on 0.8 mm tube diameter. Results indicate enhancements of the convective heat transfer coefficient as a function of Reynolds number and volume fractions. An average enhancement of heat transfer coefficient of 50 % was observed over the base fluid. An overall increase of pumping force varying from 20 to 30 % over the flowing range is observed. The results suggest an optimum MWCNT volume fraction point of 0.1 % which gives the best heat transfer enhancement.

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

    PubMed

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

    2012-11-01

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

  18. Optical properties of fluorescent zigzag graphene quantum dots derived from multi-walled carbon nanotubes

    SciTech Connect

    Chen, Wei; Li, Fushan Wu, Chaoxing; Guo, Tailiang

    2014-02-10

    Graphene quantum dots (GQDs), which are edge-bound nanometer-size graphene pieces, have fascinating electronic and optical properties due to their quantum confinement and edge effect. In this paper, GQDs were synthesized by using acid treatment and chemical exfoliation of multi-walled carbon nanotubes (MWCNTs). The structure of the GQDs was investigated by transmission electron microscope. The GQDs have a uniform size distribution, zigzag edge structure and two-dimensional morphology. The results indicated that the GQDs have bright blue emission upon UV excitation. The highly fluorescent GQDs exhibited high water solubility and good stability. It is shown that the acid treatment of MWCNTs leads to the formation of the functional group in zigzag sites, which results in the pH-dependent fluorescence of the GQDs.

  19. 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.

  20. Heating efficiency of multi-walled carbon nanotubes in the first and second biological windows.

    PubMed

    Maestro, Laura Martínez; Haro-González, Patricia; del Rosal, Blanca; Ramiro, Julio; Caamaño, A J; Carrasco, Elisa; Juarranz, Angeles; Sanz-Rodríguez, Francisco; Solé, José García; Jaque, Daniel

    2013-09-07

    Quantum dot based-thermometry, in combination with double beam confocal microscopy and infrared thermal imaging, has been used to investigate the heating efficiency of multi-walled carbon nanotubes (MWCNTs) under optical excitation within the first (808 nm) and second (1090 nm) biological windows as well as in the spectral region separating them (980 nm). It has been found that for the three excitation wavelengths the heating efficiency of MWCNTs (10 nm in diameter and 1.5 μm in length) is close to 50%. Despite this "flat" heating efficiency, we have found that the excitation wavelength is, indeed, critical during in vivo experiments due to the spectral dependence of both tissue absorption and scattering coefficients. It has been concluded that efficiency and selectivity of in vivo photothermal treatments based on MWCNTs are simultaneously optimized when laser irradiation lies within the first or second biological window.

  1. Improvement in characteristics of natural rubber nanocomposite by surface modification of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Takeuchi, Kenji; Noguchi, Toru; Ueki, Hiroyuki; Niihara, Ken-ichi; Sugiura, Tomoyoshi; Inukai, Shigeki; Fujishige, Masatsugu

    2015-05-01

    We aim to develop high-level applications of NR through the innovative use of multi-walled carbon nanotubes (MWCNTs) to improve reinforcing performance and thermal resistance. In this study, we examined the structures and characteristics of composite materials in which NR was the matrix and MWCNTs were the fillers. We studied the properties of composites containing surface-activated MWCNTs with three different diameters. The results show that the reinforcing performance improves as MWCNT diameter decreases, while thermal resistance improves as we decrease the heat-treatment temperature. The latter occurs because adherence between MWCNTs and NR becomes stronger at lower heat-treatment temperatures. We also found that for practical applications, we need to control active sites on MWCNTs to balance adhesion against thermal resistance.

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

    SciTech Connect

    Zhao, Junhua E-mail: timon.rabczuk@uni-weimar.de; Lu, Lixin; Rabczuk, Timon E-mail: timon.rabczuk@uni-weimar.de

    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 E{sub i}I{sub i}, d, and γ, where E{sub i}I{sub i} 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.

  3. 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...

  4. 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...

  5. 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...

  6. Excellent catalytic effects of multi-walled carbon nanotube supported titania on hydrogen storage of a Mg-Ni alloy.

    PubMed

    Tan, Yajun; Zhu, Yunfeng; Li, Liquan

    2015-02-11

    Superior catalytic effects of multi-walled carbon nanotube supported titania synthesized by the sol-gel method on hydrogen storage of a Mg-Ni alloy were investigated. The excellent hydrogen storage properties were obtained: absorbed 5.60 wt% H2 within 60 s at 373 K and released 6.08 wt% H2 within 600 s at 553 K.

  7. 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...

  8. Adsorption of methyl green dye onto multi-walled carbon nanotubes decorated with Ni nanoferrite

    NASA Astrophysics Data System (ADS)

    Bahgat, Mohamed; Farghali, Ahmed Ali; El Rouby, Waleed; Khedr, Mohamed; Mohassab-Ahmed, Mohassab Y.

    2013-06-01

    This research was carried out to evaluate the capability of multi-walled carbon nanotubes (CNTs) and NiFe2O4-decorated multi-walled carbon nanotubes (NiFe2O4-CNTs) toward waste water treatment relevant to organic dyes. CNTs were prepared via chemical vapor deposition method. NiFe2O4-CNTs were prepared by in-situ chemical precipitation of metal hydroxides followed by hydrothermal processing. The samples were characterized using XRD and TEM. The adsorption efficiency of CNTs and NiFe2O4-CNTs of methyl green dye at various temperatures was examined. The adsorbed amount increased with the CNTs and NiFe2O4-CNTs dosage. The linear correlation coefficients and standard deviations of Langmuir and Freundlich isotherms were determined. It was found that Langmuir isotherm fitted the experimental results well in both adsorption cases n of methyl green onto CNTs and NiFe2O4-CNTs. Kinetics analyses were conducted using pseudo first-order, second-order and the intraparticle diffusion models. The results showed that the adsorption kinetics was controlled by a pseudo second-order model for adsorption of methyl green onto CNTs and best controlled by pseudo first-order in case of NiFe2O4-CNTs. Changes in the free energy of adsorption (Δ G°), enthalpy (Δ H°), entropy (Δ S°), and the activation energy ( E a) were determined. The Δ H°, Δ G° and E a values indicated that the adsorption of methyl green onto MWCNTs and NiFe2O4-MWCNTs was physisorption.

  9. Functionalization of nitrogen-doped carbon nanotubes with gallium to form Ga-CN(x)-multi-wall carbon nanotube hybrid materials.

    PubMed

    Simmons, Trevor J; Hashim, Daniel P; Zhan, Xiaobo; Bravo-Sanchez, Mariela; Hahm, Myung Gwan; López-Luna, Edgar; Linhardt, Robert J; Ajayan, Pulickel M; Navarro-Contreras, Hugo; Vidal, Miguel A

    2012-08-17

    In an effort to combine group III-V semiconductors with carbon nanotubes, a simple solution-based technique for gallium functionalization of nitrogen-doped multi-wall carbon nanotubes has been developed. With an aqueous solution of a gallium salt (GaI(3)), it was possible to form covalent bonds between the Ga(3+) ion and the nitrogen atoms of the doped carbon nanotubes to form a gallium nitride-carbon nanotube hybrid at room temperature. This functionalization was evaluated by x-ray photoelectron spectroscopy, energy dispersive x-ray spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy.

  10. Adsorption of diuron, fluridone and norflurazon on single-walled and multi-walled carbon nanotubes.

    PubMed

    Sun, Ke; Zhang, Zheyun; Gao, Bo; Wang, Ziying; Xu, Dongyu; Jin, Jie; Liu, Xitao

    2012-11-15

    The sorption behaviors of diuron (DIU), fluridone (FLU) and norflurazon (NOR) by a single-walled carbon nanotube (SWCNT) and three multi-walled carbon nanotubes (MWCNT) samples including MWCNT10 (<10nm, outer diameter), MWCNT20 (10-20 nm), and MWCNT40 (20-40 nm) were investigated. All adsorption isotherms were nonlinear and were well fitted with the Freundlich model and Dubinin Ashtakhov (DA) model. The linear relationships between the organic carbon (OC)-normalized saturated adsorption capacity (Q(0)(OC)) and surface area (SA) suggest that SA is presumably responsible for the adsorption of DIU and NOR on CNTs. While FLU, DIU, and NOR OC-normalized distribution coefficients (logK(OC)) of CNTs increased with increasing their hydrophobicity (logK(OW)) and the positive relationships between the logK(OW)-normalized logK(OC) (i.e., logK(OC)/logK(OW)) of FLU, DIU, and NOR and their hydrogen bonding ability indicate that the adsorption of FLU, DIU and NOR was mainly controlled by the hydrophobic interaction and hydrogen bonding. The higher logK(OC) or Q(0)(OC) values of MWCNT10 and SWCNT relative to other large MWCNTs and carbonaceous adsorbents suggest that MWCNT10 has the potential to serve as an adsorbent used to reduce the mobility of herbicides in agricultural and environmental applications. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Solid-contact pH-selective electrode using multi-walled carbon nanotubes.

    PubMed

    Crespo, Gastón A; Gugsa, Derese; Macho, Santiago; Rius, F Xavier

    2009-12-01

    Multi-walled carbon nanotubes (MWCNT) are shown to be efficient transducers of the ionic-to-electronic current. This enables the development of a new solid-contact pH-selective electrode that is based on the deposition of a 35-microm thick layer of MWCNT between the acrylic ion-selective membrane and the glassy carbon rod used as the electrical conductor. The ion-selective membrane was prepared by incorporating tridodecylamine as the ionophore, potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate as the lipophilic additive in a polymerized methylmethacrylate and an n-butyl acrylate matrix. The potentiometric response shows Nernstian behaviour and a linear dynamic range between 2.89 and 9.90 pH values. The response time for this electrode was less than 10 s throughout the whole working range. The electrode shows a high selectivity towards interfering ions. Electrochemical impedance spectroscopy and chronopotentiometry techniques were used to characterise the electrochemical behaviour and the stability of the carbon-nanotube-based ion-selective electrodes.

  12. Plasma-activated multi-walled carbon nanotube-polystyrene composite substrates for biosensing

    NASA Astrophysics Data System (ADS)

    Fernández-Sánchez, César; Pellicer, Eva; Orozco, Jahir; Jiménez-Jorquera, Cecilia; Lechuga, Laura M.; Mendoza, Ernest

    2009-08-01

    Carbon nanotube-polymer composites have shown to be suitable materials for the fabrication of electrochemical transducers. The exposed surface of these materials is commonly passivated by a very thin layer of the polymer component that buries the conductive carbon particles. Working with multi-walled carbon nanotube-polystyrene (MWCNT-PS) composite structures, it was previously described how a simple low power oxygen plasma process produced an effective etching of the composite surface, thereby exposing the conductive surface of CNTs. This work shows how this plasma process not only gave rise to a suitable composite conductive surface for electrochemical sensing but simultaneously exposed and created a high density of oxygen-containing functional groups at both the CNT and the PS components, without affecting the material's mechanical stability. These chemical groups could be effectively modified for the stable immobilization of biological receptors. A detailed chemical characterization of the plasma-activated composite surface was possible using x-ray photoelectron spectroscopy. The material reactivity towards the tethering of a protein was studied and protein-protein interactions were then evaluated on the modified composite transducers by scanning electron microscopy. Finally, an amperometric immunosensor approach for the detection of rabbit Immunoglobulin G target analyte was described and a minimum concentration of 3 ng ml-1 was easily measured.

  13. 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.

  14. Fabrication and characterization of a zirconia/multi-walled carbon nanotube mesoporous composite.

    PubMed

    Wang, Zonghua; Xia, Jianfei; Xia, Yanzhi; Lu, Caiyu; Shi, Guoyu; Zhang, Feifei; Zhu, Fuqiang; Li, Yanhui; Xia, Linhua; Tang, Jie

    2013-10-01

    A zirconia/multi-walled carbon nanotube (ZrO2/MWCNT) mesoporous composite was fabricated via a simple method using a hydrothermal process with the aid of the cationic surfactant cetyltrimethylammonium bromide (CTAB). Transmission electron microscopy (TEM), N2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques were used to characterize the as-made samples. The cubic ZrO2 nanocrystallites were observed to overlay the surface of MWCNTs, which resulted in the formation of a novel mesoporous-nanotube composite. On the basis of a TEM analysis of the products from controlled experiment, the role of the acid-treated MWCNTs and CTAB was proposed to explain the formation of the mesoporous-nanotube structure. The as-made composite possessed novel properties, such as a high surface area (312 m(2)·g(-1)) and a bimodal mesoporous structure (3.18 nm and 12.4 nm). It was concluded that this composite has important application value due to its one-dimensional hollow structure, excellent electric conductivity and large surface area.

  15. Electrical response of liquid crystal cells doped with multi-walled carbon nanotubes

    PubMed Central

    García-García, Amanda; Vergaz, Ricardo; Algorri, José Francisco; Quintana, Xabier

    2015-01-01

    Summary The inclusion of nanoparticles modifies a number of fundamental properties of many materials. Doping of nanoparticles in self-organized materials such as liquid crystals may be of interest for the reciprocal interaction between the matrix and the nanoparticles. Elongated nanoparticles and nanotubes can be aligned and reoriented by the liquid crystal, inducing noticeable changes in their optical and electrical properties. In this work, cells of liquid crystal doped with high aspect ratio multi-walled carbon nanotubes have been prepared, and their characteristic impedance has been studied at different frequencies and excitation voltages. The results demonstrate alterations in the anisotropic conductivity of the samples with the applied electric field, which can be followed by monitoring the impedance evolution with the excitation voltage. Results are consistent with a possible electric contact between the coated substrates of the LC cell caused by the reorientation of the nanotubes. The reversibility of the doped system upon removal of the electric field is quite low. PMID:25821679

  16. 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.

  17. Quantitative evaluation of multi-walled carbon nanotube uptake in wheat and rapeseed.

    PubMed

    Larue, Camille; Pinault, Mathieu; Czarny, Bertrand; Georgin, Dominique; Jaillard, Danielle; Bendiab, Nedjma; Mayne-L'Hermite, Martine; Taran, Frédéric; Dive, Vincent; Carrière, Marie

    2012-08-15

    Environmental contamination with carbon nanotubes would lead to plant exposure and particularly exposure of agricultural crops. The only quantitative exposure data available to date which can be used for risk assessment comes from computer modeling. The aim of this study was to provide quantitative data relative to multi-walled carbon nanotube (MWCNT) uptake and distribution in agricultural crops, and to correlate accumulation data with impact on plant development and physiology. Roots of wheat and rapeseed were exposed in hydroponics to uniformly (14)C-radiolabeled MWCNTs. Radioimaging, transmission electron microscopy and raman spectroscopy were used to identify CNT distribution. Radioactivity counting made it possible absolute quantification of CNT accumulation in plant leaves. Impact of CNTs on seed germination, root elongation, plant biomass, evapotranspiration, chlorophyll, thiobarbituric acid reactive species and H(2)O(2) contents was evaluated. We demonstrate that less than 0.005‰ of the applied MWCNT dose is taken up by plant roots and translocated to the leaves. This accumulation does not impact plant development and physiology. In addition, it does not induce any modifications in photosynthetic activity nor cause oxidative stress in plant leaves. Our results suggest that if environmental contamination occurs and MWCNTs are in the same physico-chemical state than the ones used in the present article, MWCNT transfer to the food chain via food crops would be very low. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. 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.

  19. The synthesis of a copper/multi-walled carbon nanotube hybrid nanowire in a microfluidic reactor

    NASA Astrophysics Data System (ADS)

    Peng, Yitian; Chen, Quanfang

    2009-06-01

    Metallic nanowires are promising as components in nanoscale systems including nanoelectronics. However, the application of nanowires made of a single material is limited by the properties of the material used. We report here an effort to fabricate a hybrid copper-coated carbon nanotube (CNT)—Cu/CNT nanowire, using a microfluidic reactor. The fabrication of copper/multi-walled carbon nanotube (MWCNT) hybrid nanowires was realized by an electroless copper deposition technique in which MWCNT templates and an electrolyte were introduced separately into the microfluidic reactor. The morphology and structure of the Cu/MWCNT hybrid nanowire were studied by means of transmission electron microscopy (TEM), selected-area electron diffraction (SAED), scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX), as well as XRD. Results reveal that the fabricated Cu/MWCNT hybrid nanowires are continuously covered by crystallized copper with a preferred crystal orientation along the (111) planes in the radial direction of the MWCNTs. These structural properties are attributed to the unique reaction environment including laminar flow and diffusion-controlled reaction.

  20. The synthesis of a copper/multi-walled carbon nanotube hybrid nanowire in a microfluidic reactor.

    PubMed

    Peng, Yitian; Chen, Quanfang

    2009-06-10

    Metallic nanowires are promising as components in nanoscale systems including nanoelectronics. However, the application of nanowires made of a single material is limited by the properties of the material used. We report here an effort to fabricate a hybrid copper-coated carbon nanotube (CNT)-Cu/CNT nanowire, using a microfluidic reactor. The fabrication of copper/multi-walled carbon nanotube (MWCNT) hybrid nanowires was realized by an electroless copper deposition technique in which MWCNT templates and an electrolyte were introduced separately into the microfluidic reactor. The morphology and structure of the Cu/MWCNT hybrid nanowire were studied by means of transmission electron microscopy (TEM), selected-area electron diffraction (SAED), scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX), as well as XRD. Results reveal that the fabricated Cu/MWCNT hybrid nanowires are continuously covered by crystallized copper with a preferred crystal orientation along the (111) planes in the radial direction of the MWCNTs. These structural properties are attributed to the unique reaction environment including laminar flow and diffusion-controlled reaction.

  1. Effects of Functionalized and Raw Multi-Walled Carbon Nanotubes on Soil Bacterial Community Composition

    PubMed Central

    Kerfahi, Dorsaf; Tripathi, Binu M.; Singh, Dharmesh; Kim, Hyoki; Lee, Sujin; Lee, Junghoon; Adams, Jonathan M.

    2015-01-01

    Carbon nanotubes (CNTs) are widely used in industry, but their environmental impacts on soil microbial communities are poorly known. In this paper, we compare the effect of both raw and acid treated or functionalized (fCNTs) multi-walled carbon nanotubes (MWCNTs) on soil bacterial communities, applying different concentrations of MWCNTs (0 µg/g, 50 µg/g, 500 µg/g and 5000 µg/g) to a soil microcosm system. Soil DNA was extracted at 0, 2 and 8 weeks and the V3 region of the 16S rRNA gene was PCR-amplified and sequenced using paired-end Illumina bar-coded sequencing. The results show that bacterial diversity was not affected by either type of MWCNT. However, overall soil bacterial community composition, as illustrated by NMDS, was affected only by fMWCNT at high concentrations. This effect, detectable at 2 weeks, remained equally strong by 8 weeks. In the case of fMWCNTs, overall changes in relative abundance of the dominant phyla were also found. The stronger effect of fMWCNTs could be explained by their intrinsically acidic nature, as the soil pH was lower at higher concentrations of fMWCNTs. Overall, this study suggests that fMWCNTs may at least temporarily alter microbial community composition on the timescale of at least weeks to months. It appears, by contrast, that raw MWCNTs do not affect soil microbial community composition. PMID:25825905

  2. Effects of functionalized and raw multi-walled carbon nanotubes on soil bacterial community composition.

    PubMed

    Kerfahi, Dorsaf; Tripathi, Binu M; Singh, Dharmesh; Kim, Hyoki; Lee, Sujin; Lee, Junghoon; Adams, Jonathan M

    2015-01-01

    Carbon nanotubes (CNTs) are widely used in industry, but their environmental impacts on soil microbial communities are poorly known. In this paper, we compare the effect of both raw and acid treated or functionalized (fCNTs) multi-walled carbon nanotubes (MWCNTs) on soil bacterial communities, applying different concentrations of MWCNTs (0 µg/g, 50 µg/g, 500 µg/g and 5000 µg/g) to a soil microcosm system. Soil DNA was extracted at 0, 2 and 8 weeks and the V3 region of the 16S rRNA gene was PCR-amplified and sequenced using paired-end Illumina bar-coded sequencing. The results show that bacterial diversity was not affected by either type of MWCNT. However, overall soil bacterial community composition, as illustrated by NMDS, was affected only by fMWCNT at high concentrations. This effect, detectable at 2 weeks, remained equally strong by 8 weeks. In the case of fMWCNTs, overall changes in relative abundance of the dominant phyla were also found. The stronger effect of fMWCNTs could be explained by their intrinsically acidic nature, as the soil pH was lower at higher concentrations of fMWCNTs. Overall, this study suggests that fMWCNTs may at least temporarily alter microbial community composition on the timescale of at least weeks to months. It appears, by contrast, that raw MWCNTs do not affect soil microbial community composition.

  3. Electrical Properties of Single-Walled/Multi-Walled Carbon-Nanotubes Filled Polycarbonate Nanocomposites

    NASA Astrophysics Data System (ADS)

    Sain, P. K.; Goyal, R. K.; Prasad, Y. V. S. S.; Bhargava, A. K.

    2017-01-01

    The work focused on development of flexible and light weight polycarbonate based nanocomposites containing single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) prepared by solution method for electronic applications. X-ray diffractometry (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used for the characterization. XRD confirmed the presence of CNTs in the nanocomposites. TEM and SEM both revealed the dispersion of CNTs in the matrix. Percolation threshold was found to occur at 0.5 vol.% for SWCNTs and 4 vol.% for MWCNTs filled polycarbonate nanocomposites. The electrical conductivity, relative dielectric constant and dissipation factor of the nanocomposites were increased abruptly above percolation threshold. The maximum achieved electrical conductivity and the relative dielectric constant of the nanocomposites was found 10-4 S/cm and 108, respectively in both the nanocomposites. The best achieved combination of relative dielectric constant and dissipation factor was found in 1 vol.% SWCNT-PC nanocomposite. The relative dielectric constant of the nanocomposites was almost temperature independent from room temperature to 200°C.

  4. 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

    2017-08-01

    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.

  5. Cs + sputtered clusters from multi-walled carbon nanotubes, graphite and the structural transformations

    NASA Astrophysics Data System (ADS)

    Ahmad, Shoaib; Javeed, Sumera; Zeeshan, Sumaira; Naeem, Athar; Saadat, Shahzad; Yousuf, Muhammad; Khaleel, Muhammad; Mushtaq, Ahsan; Shahnawaz, Muhammad

    2012-01-01

    Experiments with multi-walled carbon nanotubes (MWCNTs) and graphite as targets in a source of negative ions with cesium sputtering show that MWCNTs with nanometer radii and micrometer length can be compared with micrometer-size graphite grains. The comparative study helps to better understand the irradiation effects, including the formation, sputtering of carbon clusters and the resulting structural changes. The simultaneous adsorption of Cs 0 on the surface and bombardment by energetic Cs + ions is shown to play a role in cluster formation and sputtering of carbon atoms and clusters (C x; x ⩾ 1) and the cesium-substituted carbon clusters (CsC x) as anions. Qualitative and quantitative outputs of sputtered species are related to their respective structures. Structural changes are shown to occur in MWCNTs and seen in scanning electron micrographs. The individual identity of the heavily bombarded MWCNTs may have given way to the merged structures while effects on the structure of heavily irradiated graphite grains size needs to be further investigated.

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

    PubMed

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

    2014-01-01

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

  7. 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

  8. Effects of multi-walled carbon nanotubes (MWCNT) under Neisseria meningitidis transformation process

    PubMed Central

    2011-01-01

    Background This study aimed at verifying the action of multi-walled carbon nanotubes (MWCNT) under the naturally transformable Neisseria meningitidis against two different DNA obtained from isogenic mutants of this microorganism, an important pathogen implicated in the genetic horizontal transfer of DNA, causing the escape of the principal vaccination measured worldwide by the capsular switching process. Materials and methods The bacterium receptor strain C2135 was cultivated and had its mutant DNA donor M2 and M6, which received a receptor strain and MWCNT at three different concentrations. The inhibition effect of DNAse on the DNA in contact with nanoparticles was evaluated. Results The results indicated an in increase in the transformation capacity of N. meninigtidis in different concentrations of MWCNT when compared with negative control without nanotubes. A final analysis of the interaction between DNA and MWCNT was carried out using Raman Spectroscopy. Conclusion These increases in the transformation capacity mediated by MWCNT, in meningococci, indicate the interaction of these particles with the virulence acquisition of these bacteria, as well as with the increase in the vaccination escape process. PMID:22088149

  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.

    2017-06-01

    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. Multifunctional properties of multi-wall carbon nanotubes/cyanate-ester nanocomposites and CFRPs

    NASA Astrophysics Data System (ADS)

    Baltopoulos, A.; Fiamegkou, E.; Vavouliotis, A.; Karapappas, P.; Athanasopoulos, N.; Fotiou, I.; Kostopoulos, V.; Maagt, P. D.; Rohr, T.

    2009-07-01

    The incorporation of multi-wall carbon nanotubes at weight fractions of 0.5% wt. and 1% wt. in a PRIMASET cyanate ester system (PT-30) was examined. The thermo-mechanical and electrical properties of the developed nanopolymers were investigated and were compared with the neat matrix properties. A preparation method was developed for the incorporation of the fillers in the resin system. The phenomenon of re-agglomeration of nanotubes took place in the first stages of curing schedule but nevertheless according to the SEM images a good dispersion was generally achieved. DSC, DMA, TGA and thermal conductivity tests were performed for the thermal characterization. For the electrical characterization, AC and DC measurements took place. No significant change in the glass transition temperature (Tg), thermal conductivity and mass loss values was observed in comparison with the neat resin systems. However, in both cases the improvement of electrical conductivity was about nine orders of magnitude, indicating that percolation had been achieved. The elastic modulus in bending was examined and a slight increase was observed in direct comparison with the neat resin. Finally, the developed doped nanopolymer was used as matrix for the CFRPs manufacturing. A full manufacturing protocol was developed in order to overcome the challenging issues concerning the cyanate esters' handling and manufacturing processes. Moreover AC and DC measurements were performed along with thermal conductivity measurements and TMA. The produced modified composites were tested for short beam strength.

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

    PubMed Central

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

    2014-01-01

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

  12. "Green" functionalization of pristine multi-walled carbon nanotubes with long-chain aliphatic amines.

    PubMed

    Basiuk, Elena V; Ochoa-Olmos, Omar; Contreras-Torres, Flavio F; Meza-Laguna, Víctor; Alvarez-Zauco, Edgar; Puente-Lee, Iván; Basiuk, Vladimir A

    2011-06-01

    Short pristine multi-walled carbon nanotubes (MWNTs) were functionalized with a series of long-chain (including polymeric) aliphatic amines, namely octadecylamine (ODA), 1,8-diaminooctane (DO), polyethylene glycol diamine (PEGDA) and polyethylenimine (PEI), via two "green" approaches: (1) gas-phase functionalization (for volatile ODA and DO) and (2) direct heating in the melt (for polymeric PEGDA and PEI). Both of them consist in one-step reaction between MWNTs and amine without the use of organic solvents. The nanostructures obtained were characterized by using infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. It was observed that both solvent-free methods were efficient in the nanotube functionalization, and the nanostructures of variable solubility and morphology were obtained depending on the amines attached. ODA, PEGDA and PEI-functionalized MWNTs were found to be soluble in propanol, meanwhile the MWNTs-PEGDA and MWNTs-PEI were soluble in water as well. The attachment of 1,8-diaminooctane onto MWNTs resulted in cross-linked stable nanostructure.

  13. 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.

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

    PubMed

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

    2012-11-15

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

  15. Contact resistance of multi-walled carbon nanotube/natural rubber nanocomposites with metallic ball

    NASA Astrophysics Data System (ADS)

    Sugiura, Tomoyoshi; Fujishige, Masatsugu; Noguchi, Toru; Ueki, Hiroyuki; Niihara, Ken-ichi; Takeuchi, Kenji

    2016-12-01

    This paper reports on the contact resistance (Rc) between carbon filler/natural rubber (NR) nanocomposite and gold ball: three varieties of nanocomposites were prepared from carbon black (CB) and two kinds of multi-walled carbon nanotubes (MWCNTs) with different diameter. Rc of MWCNT/NR nanocomposite was remarkably less than that of CB/NR nanocomposites. The relationship between Rc of MWCNT/NR nanocomposites and applied load was expressed in the formula, Rc=C·P-n (P: load, C and n: constant): for the MWCNTs (diameters of 13 nm)/NR and MWCNTs (diameters of 67 nm)/ NR nanocomposites, they were expressed as Rc=1724·P-0.6 and Rc=344·P-0.37, respectively. The former (MWCNT, ϕ13 nm) showed higher Rc than the latter (MWCNT, ϕ67 nm) over whole region of applied load. The mechanical hardness of the former was higher (90 HsA) than that of the latter (82 HsA). Therefore, the smaller contact area between the nanocomposite and gold ball of the former resulted in higher Rc. The apparent specific contact resistivity was calculated from the observed values of Rc and contact area: 130 Ω mm2 and 127 Ω mm2 for the former (MWCNT, ϕ13 nm) and the latter (MWCNT, ϕ67 nm), respectively.

  16. Purification and dispersibility of multi-walled carbon nanotubes in aqueous solution

    NASA Astrophysics Data System (ADS)

    Chen, Yuanzhao; Li, Zhenxia; Zhao, Yang

    2016-12-01

    In this paper, the pristine multi-walled carbon nanotubes (P-MWCNTs) were purified either by the high temperature treatment (HT-MWCNTs) or by concentrated acid treatment (CA-MWCNTs). The HT-MWCNTs were prepared by heating at 500°C, while the CA-MWCNTs were treated by the mixture of concentrated nitric and sulfuric acids taken in a volume ratio of 3: 1. Ultrasonic processing and surfactants were utilized to achieve homogenous MWCNTs suspensions. The HT-MWCNTs and CA-MWCNTs were characterized by thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). Among these three MWCNTs, the prepared homogeneously dispersed MWCNTs suspensions were characterized by UV-Vis absorbency and transmission electron microscopy (TEM). Finally, the dispersion mechanism was discussed. The results showed that both high temperature treatment and concentrated acid treatment can be used for purification of the P-MWCNTs, removing the amorphous carbon and other impurities. In these suspensions, the purified MWCNTs showed a better dispersibility in aqueous solution. The high temperature treatment was a kind of physical purification treatment method and it just burned the amorphous carbon away and strengthened the structure of MWCNTs, while the concentrated acid treatment was a chemical purification treatment method and this chemical treatment method grafted more effective groups to improve the dispersibility of MWCNTs.

  17. 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

  18. 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

  19. Magnetoresistive polyaniline/multi-walled carbon nanotube nanocomposites with negative permittivity

    NASA Astrophysics Data System (ADS)

    Gu, Hongbo; Guo, Jiang; He, Qingliang; Jiang, Yuan; Huang, Yudong; Haldolaarachige, Neel; Luo, Zhiping; Young, David P.; Wei, Suying; Guo, Zhanhu

    2013-12-01

    Contrary to the observed positive giant magnetoresistance (GMR) in as-received multi-walled carbon nanotubes (MWNTs), pure polyaniline (PANI) synthesized with Cr(vi) as oxidant and MWNTs/PANI nanocomposites with ammonium persulfate (APS) as oxidant, a room temperature negative GMR of around -2% was reported in MWNTs/PANI nanocomposites with Cr(vi) as oxidant. Different from a frequency switch of permittivity from negative to positive in MWNTs/PANI nanocomposites with APS as oxidant, unique negative permittivity was observed in MWNTs/PANI nanocomposites with Cr(vi) as oxidant within the measured frequency range from 20 to 2 × 106 Hz. The obtained unique negative permittivity was explained by the plasma frequency from the Drude model, at which the permittivity changes from negative to positive and the material changes from a metamaterial to an ordinary dielectric medium. The observed positive and negative GMR behaviors in these disordered systems as verified by the temperature dependent resistivity exploration were well explained through a wave-function shrinkage model and orbital magnetoconductivity theory by calculating the changed localization length (a0).Contrary to the observed positive giant magnetoresistance (GMR) in as-received multi-walled carbon nanotubes (MWNTs), pure polyaniline (PANI) synthesized with Cr(vi) as oxidant and MWNTs/PANI nanocomposites with ammonium persulfate (APS) as oxidant, a room temperature negative GMR of around -2% was reported in MWNTs/PANI nanocomposites with Cr(vi) as oxidant. Different from a frequency switch of permittivity from negative to positive in MWNTs/PANI nanocomposites with APS as oxidant, unique negative permittivity was observed in MWNTs/PANI nanocomposites with Cr(vi) as oxidant within the measured frequency range from 20 to 2 × 106 Hz. The obtained unique negative permittivity was explained by the plasma frequency from the Drude model, at which the permittivity changes from negative to positive and the material

  20. Multi-walled carbon nanotube-graphene-polyaniline multiphase nanocomposite with superior electromagnetic shielding effectiveness

    NASA Astrophysics Data System (ADS)

    Gupta, Tejendra K.; Singh, Bhanu Pratap; Mathur, Rakesh B.; Dhakate, Sanjay R.

    2013-12-01

    The multiphase approach was adapted to enhance the electromagnetic interference (EMI) shielding effectiveness (SE) of polyaniline (PANI) based nanocomposites. The natural graphite flakes (NGF) incorporated modified PANI was used for the development of multi-walled carbon nanotubes (MWCNTs) based nanocomposites. In PANINGF-MWCNTs composites, multilayer graphene was synthesized in situ by ball milling. The resultant PANINGF-MWCNTs nanocomposites were characterized by different techniques. It was revealed from the transmission electron microscope (TEM) observation that in situ derived multilayer graphene acts as a bridge between PANI and MWCNTs, and plays a significant role for improving the properties of multiphase nanocomposites. It was observed that EMI-SE increases with increasing the MWCNTs content from 1 to 10 wt% in the multiphase nanocomposites. The maximum value of total EMI-SE was -98 dB of nanocomposite with 10 wt% of MWCNTs content. The high value of EMI-SE is dominated by the absorption phenomenon which is due to the collective effect of increase in space charge polarization and decrease in carrier mobility. The decrease in carrier mobility has a positive effect on the shore hardness value due to the strong interaction between the reinforcing constituent in multiphase nanocomposites. As a consequence, shore hardness increases from 56 to 91 at 10 wt% of MWCNTs.The multiphase approach was adapted to enhance the electromagnetic interference (EMI) shielding effectiveness (SE) of polyaniline (PANI) based nanocomposites. The natural graphite flakes (NGF) incorporated modified PANI was used for the development of multi-walled carbon nanotubes (MWCNTs) based nanocomposites. In PANINGF-MWCNTs composites, multilayer graphene was synthesized in situ by ball milling. The resultant PANINGF-MWCNTs nanocomposites were characterized by different techniques. It was revealed from the transmission electron microscope (TEM) observation that in situ derived multilayer

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

    NASA Astrophysics Data System (ADS)

    Vasileiou, Alexandros; Docoslis, Aristides; Kontopoulou, Marianna

    2015-05-01

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

  2. Ligand-modified multi-walled carbon nanotubes for potentiometric detection of silver.

    PubMed

    Yang, Chunli; Chai, Yaqin; Yuan, Ruo; Guo, Junxiang; Jia, Feng

    2012-01-01

    Three novel hybrid materials have been synthesized by ligands: N-(2-vinylsulfanyl-ethylidene)-benzene-1,2-dimine (SBD), N-pyridin-2-ylmethylene-benzene-1,2-dimine (NBD) and N-furan-2-ylmethylene-benzene-1,2-dimine (OBD), covalently linking to multi-walled carbon nanotubes (MWCNTs). These MWCNT hybrid materials were used both as ionophores and as ion-to-electron transducers to construct Ag(+) carbon paste electrodes. The resulting electrodes show higher selectivity to Ag(+) than other cations tested. Among the three electrodes, the electrode based on SBD-g-MWCNTs with optimum composition shows the best performance to Ag(+). It exhibits an excellent Nernstian response to Ag(+) in the concentration range from 8.8 × 10(-8) to 1.0 × 10(-1) M with a detection limit of 6.3 × 10(-8) M, and it can also be used over a wide pH range of 3.0-8.0 with a quick response time of 5 s. The response mechanism of the proposed electrode was also investigated by using AC impedance and UV-vis spectroscopy techniques.

  3. 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

  4. Electrochemistry of metoclopramide at multi-walled carbon nanotube modified electrode and its voltammetric detection.

    PubMed

    Guo, Wei; Geng, Mingjiang; Zhou, Lingyun

    2012-01-01

    A simple, sensitive and inexpensive electrochemical method was developed for the determination of metoclopramide (MCP) with a multi-wall carbon nanotube (MWNT) modified glassy carbon electrode (GCE). MWNT was dispersed into polyacrylic acid (PAA); the aqueous suspension was then cast on GCE electrodes, forming MWNT-PAA films after evaporation of the solvent. The electrochemical behavior of MCP at the MWNT-modified electrode was investigated in detail. Compared with the bare GCE, the MWNT-modified electrode exhibits electrocatalytic activity to the oxidation of MCP because of the significant oxidation peak-current enhancement. Furthermore, various experimental parameters, such as the solution pH value, the amount of MWNT-PAA suspension and accumulation conditions were optimized for the determination of MCP. Based on the electrocatalytic effect of the MWNT-modified electrode, linear sweep voltammetry (LSV) was developed for the determination of MCP with the linear response in the range from 1.0 × 10(-7) to 1.0 × 10(-5) mol L(-1) and a detection limit of 5.0 × 10(-8) mol L(-1). The method has been successfully applied to the determination of MCP in commercial MCP tablets.

  5. 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.

  6. Effects of single and multi walled carbon nanotubes on macrophages: cyto and genotoxicity and electron microscopy.

    PubMed

    Di Giorgio, Maria Laura; Di Bucchianico, Sebastiano; Ragnelli, Anna Maria; Aimola, Pierpaolo; Santucci, Sandro; Poma, Anna

    2011-05-18

    Production of nanotechnology-based materials is increasing worldwide: it is essential to evaluate their potential toxicity. Among these nanomaterials, carbon nanotubes (CNTs) have tremendous potential in many areas of research and applications. We have investigated the cyto- and genotoxic effects of single and multi-walled CNTs (SWCNTs, MWCNTs) and carbon black (CB) on the mouse macrophage cell line RAW 264.7. Specifically we have investigated inflammatory response, release of tumor necrosis factor-α (TNF-α), intracellular reactive oxygen species (ROS) production, cell death (both necrosis and apoptosis), chromosomal aberrations and cellular ultrastructural alteration caused by CB, MWCNTs and SWCNTs. Our data confirm that both CNTs and CB are cyto and geno-toxic to RAW 264.7 mouse macrophages. CNTs exposure induced ROS release, necrosis and chromosomal aberrations but did not cause an inflammatory response. In addition CNTs induce ultrastructural damage and apoptosis. CNTs penetrate the cell membrane and individual MWCNTs are seen associated with the nuclear envelope. 2011 Elsevier B.V. All rights reserved.

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

    PubMed Central

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

    2016-01-01

    The world-wide production of carbon nanotubes (CNTs) has increased substantially in the last decade, leading to occupational exposures. There is a paucity of exposure data of workers involved in the commercial production of CNTs. The goals of this study were to assess personal exposure to multi-walled carbon nanotubes (MWCNTs) during the synthesis and handling of MWCNTs in a commercial production facility and to link these exposure levels to specific activities. Personal full-shift filter-based samples were collected, during commercial production and handling of MWCNTs, R&D activities, and office work. The concentrations of MWCNT were evaluated on the basis of EC concentrations. Associations were studied between observed MWCNT exposure levels and location and activities. SEM analyses showed MWCNTs, present as agglomerates ranging between 200nm and 100 µm. Exposure levels of MWCNTs observed in the production area during the full scale synthesis of MWCNTs (N = 23) were comparable to levels observed during further handling of MWCNTs (N = 19): (GM (95% lower confidence limit–95% upper confidence limit)) 41 μg m−3 (20–88) versus 43 μg m−3 (22–86), respectively. In the R&D area (N = 11) and the office (N = 5), exposure levels of MWCNTs were significantly (P < 0.05) lower: 5 μg m−3 (2–11) and 7 μg m−3 (2–28), respectively. Bagging, maintenance of the reactor, and powder conditioning were associated with higher exposure levels in the production area, whereas increased exposure levels in the R&D area were related to handling of MWCNTs powder. PMID:26613611

  8. 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.

  9. Adsorption of crystal violet onto functionalised multi-walled carbon nanotubes: Equilibrium and kinetic studies.

    PubMed

    Sabna, V; Thampi, Santosh G; Chandrakaran, S

    2016-12-01

    Synthetic dyes present in effluent from textile, paper and paint industries contain crystal violet (CV), a known carcinogenic agent. This study investigates the modification of multiwalled carbon nanotubes by acid reflux method and equilibrium and kinetic behaviour of adsorption of CV onto functionalized multi-walled carbon nanotubes (fMWNTs) in batch system. High stability of the fMWNTs suspension in water indicates the hydrophilicity of fMWNTs induced due to the formation of functional groups that make hydrogen bonds with water molecules. fMWNTs were characterized by Fourier Transform Infra Red (FTIR) spectroscopy and the functional groups present on the fMWNTs were confirmed. Characteristic variation was observed in the FTIR spectra of fMWNTs after adsorption of crystal violet onto it. Adsorption characteristics were evaluated as a function of system variables such as contact time, dosage of fMWNTs and initial concentration and pH of the crystal violet solution. Adsorption capacity of fMWNTs and percentage removal of the dye increased with increase in contact time, adsorbent dosage and pH but declined with increase in initial concentration of the dye. fMWNTs showed higher adsorption capacity compared to that of pristine MWNTs. Data showed good fit with the Langmuir and Freundlich isotherm models and the pseudo-second order kinetic model; the maximum adsorption capacity was 90.52mg/g. Kinetic parameters such as rate constants, equilibrium adsorption capacities and regression coefficients were estimated. Results indicate that fMWNTs are an effective adsorbent for the removal of crystal violet from aqueous solution.

  10. Optimisation of the electromagnetic matching of manganese dioxide/multi-wall carbon nanotube composites as dielectric microwave-absorbing materials

    NASA Astrophysics Data System (ADS)

    Ting, Tzu-Hao; Chiang, Chih-Chia; Lin, Po-Chuan; Lin, Chia-Huei

    2013-08-01

    An optimised composite sample was prepared using two dielectric materials manganese dioxide (MnO2) and multi-wall carbon nanotubes (MWNTs) in an epoxy-resin matrix. Structural characterisations of both the synthesised manganese dioxide (MnO2) and the multi-wall carbon nanotubes (MWNTs) were performed by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microwave absorption properties of dielectric composites with different weight fractions of MnO2 were investigated by measuring the complex permittivity, the complex permeability and the reflection loss in the 2-18 and 18-40 GHz microwave frequency ranges using the free space method. The complex permittivity varied with the MnO2 content, and the results show that a high concentration of fillers increased the dielectric constant. Therefore, the appropriate combination of components and experimental conditions can produce materials with specific characteristic for use as wide-band microwave absorbers.

  11. Behavior of multi-walled carbon nanotubes on the porosity and microstructure of cement-based materials

    NASA Astrophysics Data System (ADS)

    Nochaiya, Thanongsak; Chaipanich, Arnon

    2011-01-01

    The porosity and microstructure of a Portland cement-multi-walled carbon nanotube composite were investigated. Multi-walled carbon nanotubes (CNTs), up to 1 wt.% of cement, synthesized by infusion chemical vapor deposition, and Portland cement type I (PC) were used to produce pastes with a water to cement ratio of 0.5. Mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) were used to characterize Portland cement-CNTs systems. MIP analysis of the results indicates that total porosity of the mixes with CNTs was found to decrease with increasing CNTs content. Moreover, an important effect of additional CNTs was a reduction in the number of mesopores, while SEM technique showed dispersion of CNTs between the hydration phases of Portland cement pastes.

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

    PubMed

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

    2009-05-30

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

  13. 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.

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

    PubMed

    Lu, Liulei; Ouyang, Dong; Xu, Weiting

    2016-05-27

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

  15. 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.

  16. Neuroprotective effect of functionalized multi-walled carbon nanotubes on spinal cord injury in rats

    PubMed Central

    Ding, Shenghao; Bao, Yinghui; Lin, Yong; Pan, Yaohua; Fan, Yiling; Wan, Jieqing; Jiang, Jiyao

    2015-01-01

    Traumatic injuries to the brain and spinal cord affect a large percentage of the world’s population. However, there are currently no effective treatments for these central nervous system (CNS) injuries. In our study, we evaluated the neuroprotective role of functionalized multi-walled carbon nanotubes (MWCNTs) carrying brain derived neurotrophic factor (BNDF), nogo-66 receptor (NgR) and Ras homolog gene family member A (RhoA) in spinal cord injury (SCI). Our results showed that transfection into rat cortical neurons with BDNF-DNA significantly elevated the expression of BDNF both in vitro and in vivo. Meanwhile, transfection with NgR-siRNA and RhoA-siRNA resulted in an obvious down-regulation of NgR and RhoA in neuron cells and in injured spinal cords. In addition, the functionalized MWCNTs carrying BDNF-DNA, NgR-siRNA and RhoA-siRNA exhibited remarkable therapeutic effects on injured spinal cord. Taken together, our study demonstrates that functionalized MWCNTs have a potential therapeutic application on repair and regeneration of the CNS. PMID:26884846

  17. Electrochemical properties of myoglobin deposited on multi-walled carbon nanotube/ciprofloxacin film.

    PubMed

    Kumar, S Ashok; Wang, Sea-Fue; Chang, Yu-Tsern; Lu, His-Chuan; Yeh, Chun-Ting

    2011-02-01

    We report the direct electrochemical and electrocatalytic properties of myoglobin (MB) on a multi-walled carbon nanotube/ciprofloxacin (MWCNT/CF) film-modified electrode. A highly homogeneous MWCNT thin-film was prepared on an electrode surface using ciprofloxacin (CF) as a dispersing agent. MB was then electrochemically deposited onto the MWCNT/CF-modified electrode. The MB/MWCNT/CF film was characterized by scanning electron microscopy and UV-visible spectroscopy (UV-vis). UV-vis spectra confirmed that MB retained its original state on the MWCNT/CF film. Direct electrochemical properties of MB on the MWCNT/CF film were investigated by cyclic voltammetry. The formal potential and electron transfer rate constant were evaluated in pH 7.2 buffer solution as -0.327V and 300s(-1), respectively. In addition, the MB/MWCNT/CF-modified electrode showed excellent electrocatalytic properties for the reduction of hydrogen peroxide (H(2)O(2)). The MB/MWCNT/CF-modified electrode was used for the detection of H(2)O(2) at concentrations from 1×10(-6)M to 7×10(-4)M in pH 7.2 buffer solution. Overall, the MB/MWCNT/CF-modified electrode was very stable and has potential for development as a H(2)O(2) sensor. Copyright © 2010 Elsevier B.V. All rights reserved.

  18. 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.

  19. 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

  20. 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.

  1. Pressureless sintering and mechanical properties of hydroxyapatite/functionalized multi-walled carbon nanotube composite.

    PubMed

    Abden, M J; Afroze, J D; Alam, M S; Bahadur, N M

    2016-10-01

    This work aims to study the optimum sintering conditions of hydroxyapatite/functionalized multi-walled carbon nanotube (HA/f-MWCNT) composite with improved mechanical properties for bone implant applications using a pressureless sintering technique. The carboxyl functional group (COOH) introduced by the acid treatment on the MWCNT surface by which HA molecules are grafted onto the surface of functionalized MWCNT with strong interfacial bonding. The composite exhibits a lower hemolytic rate of 1.27%. The flexible nature of f-MWCNT makes them bend and attached to the HA grains, indicates that f-MWCNT bear significant stress by sharing a portion of the load and it leads to improve their mechanical properties. The maximum Vickers hardness of 3.6GPa is obtained for the HA/f-MWCNT composite sintered at 1100°C, whereas the highest compressive strength of 481.7MPa and fracture toughness of 2.38MPa.m(1/2) achieved after sintering at 1150°C. This study demonstrated that HA/f-MWCNT composite create suitable structures by vacuum pressureless sintering technique to satisfy the mechanical requirements for bone tissues.

  2. 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.

  3. Direct electrochemistry and electrocatalysis of myoglobin immobilized on zirconia/multi-walled carbon nanotube nanocomposite

    SciTech Connect

    Liang, Ruping; Deng, Minqiang; Cui, Sanguan; Chen, Hong; Qiu, Jianding

    2010-12-15

    Zirconia/multi-walled carbon nanotube (ZrO{sub 2}/MWCNT) nanocomposite was prepared by hydrothermal treatment of MWCNTs in ZrOCl{sub 2}.8H{sub 2}O aqueous solution. The morphology and structure of the synthesized ZrO{sub 2}/MWCNT nanocomposite were characterized by transmission electron microscopy and X-ray diffraction analysis. It was found that ZrO{sub 2} nanoparticles homogeneously distributed on the sidewall of MWCNTs. Myoglobin (Mb), as a model protein to investigate the nanocomposite, was immobilized on ZrO{sub 2}/MWCNT nanocomposite. Ultraviolet-visible spectroscopy and electrochemical measurements showed that the nanocomposite could retain the bioactivity of the immobilized Mb to a large extent. The Mb immobilized in the composite showed excellent direct electrochemistry and electrocatalytic activity to the reduction of hydrogen peroxide (H{sub 2}O{sub 2}). The linear response range of the biosensor to H{sub 2}O{sub 2} concentration was from 1.0 to 116.0 {mu}M with the limit of detection of 0.53 {mu}M (S/N = 3). The ZrO{sub 2}/MWCNT nanocomposite provided a good biocompatible matrix for protein immobilization and biosensors preparation.

  4. Effect of p-type multi-walled carbon nanotubes for improving hydrogen storage behaviors

    SciTech Connect

    Lee, Seul-Yi; Yop Rhee, Kyong; Nahm, Seung-Hoon; Park, Soo-Jin

    2014-02-15

    In this study, the hydrogen storage behaviors of p-type multi-walled carbon nanotubes (MWNTs) were investigated through the surface modification of MWNTs by immersing them in sulfuric acid (H{sub 2}SO{sub 4}) and hydrogen peroxide (H{sub 2}O{sub 2}) at various ratios. The presence of acceptor-functional groups on the p-type MWNT surfaces was confirmed by X-ray photoelectron spectroscopy. Measurement of the zeta-potential determined the surface charge transfer and dispersion of the p-type MWMTs, and the hydrogen storage capacity was evaluated at 77 K and 1 bar. From the results obtained, it was found that acceptor-functional groups were introduced onto the MWNT surfaces, and the dispersion of MWNTs could be improved depending on the acid-mixed treatment conditions. The hydrogen storage was increased by acid-mixed treatments of up to 0.36 wt% in the p-type MWNTs, compared with 0.18 wt% in the As-received MWNTs. Consequently, the hydrogen storage capacities were greatly influenced by the acceptor-functional groups of p-type MWNT surfaces, resulting in increased electron acceptor–donor interaction at the interfaces. - Graphical abstract: Hydrogen storage behaviors of the p-type MWNTs with the acid-mixed treatments are described. Display Omitted Display Omitted.

  5. 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.

  6. Viscosity and thermal conductivity of nanofluids containing multi-walled carbon nanotubes stabilized by chitosan

    SciTech Connect

    Phuoc, Tran X.; Massoudi, Mehrdad; Chen, Ruey-Hung

    2011-01-01

    Thermal conductivity, viscosity, and stability of nanofluids containing multi-walled carbon nanotubes (MWCNTs) stabilized by cationic chitosan were studied. Chitosan with weight fraction of 0.1%, 0.2 wt%, and 0.5 wt% was used to disperse stably MWCNTs in water. The measured thermal conductivity showed an enhancement from 2.3% to 13% for nanofluids that contained from 0.5 wt% to 3 wt% MWCNTs (0.24 to 1.43 vol %). These values are significantly higher than those predicted using the Maxwell's theory. We also observed that the enhancements were independent of the base fluid viscosity. Thus, use of microconvection effect to explain the anomalous thermal conductivity enhancement should be reconsidered. MWCNTs can be used either to enhance or reduce the fluid base viscosity depending on the weight fractions. In the viscosity-reduction case, a reduction up to 20% was measured by this work. In the viscosity-enhancement case, the fluid behaved as a non-Newtonian shear-thinning fluid. By assuming that MWCNT nanofluids behave as a generalized second grade fluid where the viscosity coefficient depends upon the rate of deformation, a theoretical model has been developed. The model was found to describe the fluid behavior very well.

  7. Superconductivity in entirely end-bonded multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Haruyama, Junji; Takesue, Izumi; Kobayashi, Naoki; Chiashi, Shohei; Maruyama, Shigeo; Sugai, Toshiki; Shinohara, Hisanori

    2006-03-01

    One-dimensional (1D) systems face some obstructions that may prevent the emergence of superconductivity(SC), e.g., 1.a Tomonaga-Luttinger liquid (TLL), 2.Peierls transition, and 3.Low density of states due to VHSs. A carbon nanotube (CN) is one of the best candidates for investigating a possibility of 1D SC and its interplay with such obstructions. Only two groups have experimentally reported SC in ropes of single-walled CNs (SWNTs) and very thin SWNTs [1] to date. In addition, those interplay with 1D phenomena have never been clarified. Some theoretical papers also predicted strong correlation between TLL states and SC for SWNT ropes and importance of electron-phonon interaction for thin SWNTs [2]. Here, we report that entirely end-bonded multi-walled CNs (MWNTs) can show SC with the Tc as high as 12K [3] (about 50-times larger than Tc in former of [1]). We find that emergence of this SC and its interplay with TLL states are highly sensitive to junction structures of Au electrode/MWNTs. Only MWNTs with optimal numbers of electrically activated shells realized by the entire end-bonding can allow the SC due to intershell effects. Refs. 1.M. Kociak, et al., PRL 86, 2416 (2001); Z. K. Tang, et al., Science 292, 2462 (2001), 2.J.Gonzalez, PRL 88, 076403 (2002); R.Barnett, et al., PRB 71, 035429 (2005), 3.J.Haruyama et al., PRL Accepted

  8. The role of the iron catalyst in the toxicity of multi-walled carbon nanotubes (MWCNTs).

    PubMed

    Visalli, Giuseppa; Facciolà, Alessio; Iannazzo, Daniela; Piperno, Anna; Pistone, Alessandro; Di Pietro, Angela

    2017-09-01

    This study aimed to investigate the role of iron, used as a catalyst, in the biological response to pristine and functionalized multi-walled carbon nanotubes (p/fMWCNTs) with an iron content of 2.5-2.8%. Preliminarily, we assessed the pro-oxidant activity of MWCNTs-associated iron by an abiotic test. To evaluate iron bioavailability, we measured intracellular redox-active iron in A549 cells exposed to both MWCNT suspensions and to the cell medium preconditioned by MWCNTs, in order to assess the iron dissolution rate under physiological conditions. Moreover, in exposed cells, we detected ROS levels, 8-oxo-dG and mitochondrial function. The results clearly highlighted that MWCNTs- associated iron was not redox-active and that iron leakage did not occur under physiological conditions, including the oxidative burst of specialized cells. Despite this, in MWCNTs exposed cells, higher level of intracellular redox-active iron was measured in comparison to control and a significant time-dependent ROS increase was observed (P<0.01). Higher levels of 8-oxo-dG, a marker of oxidative DNA damage, and decreased mitochondrial function, confirmed the oxidative stress induced by MWCNTs. Based on the results we believe that oxidative damage could be attributable to the release of endogenous redox-active iron. This was due to the damage of acidic vacuolar compartment caused by endocytosis-mediated MWCNT internalization. Copyright © 2017 Elsevier GmbH. All rights reserved.

  9. Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine

    NASA Astrophysics Data System (ADS)

    Deborah, M.; Jawahar, A.; Mathavan, T.; Dhas, M. Kumara; Benial, A. Milton Franklin

    2015-03-01

    The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (0 0 2) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery.

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

    PubMed Central

    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

    2015-01-01

    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. PMID:22881873

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

    PubMed Central

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

    2016-01-01

    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. PMID:28335347

  12. 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 (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 ofmore » 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.« less

  13. 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.

  14. Multi-walled carbon nanotubes suppress potassium channel activities in PC12 cells

    NASA Astrophysics Data System (ADS)

    Xu, Haifei; Bai, Juan; Meng, Jie; Hao, Wei; Xu, Haiyan; Cao, Ji-Min

    2009-07-01

    The advancement in nanotechnology has produced technological and conceptual breakthroughs but the effects nanomaterials have on organisms at the cellular level are poorly understood. Here we report that carboxyl-terminated multi-walled carbon nanotubes (MWCNTs) act as antagonists of three types of potassium channels as assessed by whole-cell patch clamp electrophysiology on undifferentiated pheochromocytoma (PC12) cells. Our results showed that carboxyl-terminated MWCNTs suppress the current densities of Ito, IK and IK1 in a time-dependent and irreversible manner. The suppressions were most distinct 24 h after incubation with MWCNTs. However, MWCNTs did not significantly change the expression levels of reactive oxygen species (ROS) or intracellular free calcium and also did not alter the mitochondrial membrane potential (ΔΨm) in PC12 cells. These results suggest that oxidative stress was not involved in the MWCNTs suppression of Ito, IK and IK1 current densities. Nonetheless, the suppression of potassium currents by MWCNTs will impact on electrical signaling of excitable cells such as neurons and muscles.

  15. Reinforcement of epoxy-based composites by magnetically aligned multi walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Xu, Xianjuan; Lin, Song; Li, Moyu; Li, Wusheng; Jia, Xiaolong; Cai, Qing; Yang, Xiaoping

    2015-07-01

    Multi walled carbon nanotubes decorated with ferriferrous oxide nanoparticle (MWCNTs-Fe3O4) complex was used as an effective reinforcement in the polymer composites. The MWCNTs-Fe3O4 with various grafting contents of Fe3O4 nanoparticles were successfully prepared by combining in situ atom transfer radical polymerization (ATRP) and coprecipitation process, which was characterized with Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscope (TEM). The MWCNTs-Fe3O4 complex showed the strong magnetic response behavior, which could be easily aligned in an external magnetic field. The alignment state of MWCNTs-Fe3O4 complex could be modulated by adjusting the intensity of external magnetic field, grafting content of Fe3O4 nanoparticles and viscosity of the solvent. Moreover, with the addition of MWCNTs-Fe3O4, tensile strength and modulus of epoxy composites were enhanced by 12.3 and 10.9%, respectively, which was due to the reinforcing effect of the aligned MWCNTs-Fe3O4 within magnetic field.

  16. Synthesis of multi-walled carbon nanotubes/β-FeOOH nanocomposites with high adsorption capacity

    NASA Astrophysics Data System (ADS)

    Song, Hao-Jie; Liu, Lei; Jia, Xiao-Hua; Min, Chunying

    2012-12-01

    A hybrid nanostructure of multi-walled carbon nanotubes (CNTs) and β-ferric oxyhydroxide (β-FeOOH) nanoparticles is synthesized by ultrasonic-assisted in situ hydrolysis of the precursor ferric chloride and CNTs. Characterization by X-ray diffraction, scanning electron microscopy , and transmission electron microscopy establishes the nanohybrid structure of the synthesized sample. The results revealed that the surface of CNTs was uniformly assembled by numerous β-FeOOH nanoparticles and had an average diameter of 3 nm. The formation route of anchoring β-FeOOH nanoparticles onto CNTs was proposed as the intercalation and adsorption of iron ions onto the wall of CNTs, followed by the nucleation and growth of β-FeOOH nanoparticles. The values of remanent magnetization ( M r) and coercivity ( H c) of the as-synthesized CNTs/β-FeOOH nanocomposites were 0.1131 emu g, and 490.824 Oe, respectively. Furthermore, CNTs/β-FeOOH nanocomposites showed a very high adsorption capacity of Congo red and thus these nanocomposites can be used as good adsorbents and can be used for the removal of the dye of Congo red from the waste water system.

  17. A gas sensor using a multi-walled carbon nanotube sheet to detect oxygen molecules.

    PubMed

    Jung, Daewoong; Lee, Kyung H; Kim, Donghyun; Overzet, Lawrence J; Lee, Gil S

    2013-12-01

    A gas sensor using a multi-walled carbon nanotube (MWCNT) sheet, which can detect oxygen (O2) gas, is presented and its output characteristics are evaluated in this study. A simple, cost effective and novel fabrication technique is described compared to dispersing CNTs into a liquid or polymer. The sheets are spun from a MWCNT forest grown on a silicon substrate; its electrical resistance decreases linearly with O2 exposure. The MWCNT sheet has a large surface area and many individual MWCNT contact points; this leads to a linear sensitivity, a fast response time, repeatability, and stability. It is well known that the surface distribution and areal density of MWCNTs have a significantly affect on their sensing characteristics. The sensors fabricated using dispersed CNTs on a substrate, either with separated CNTs of low density or with overlapping CNTs of low resistance, reveal much lower sensitivities. The large surface area and uniform distribution of the gas sensor, however, allow for the higher interaction of the MWCNTs with the O2 molecules, increasing the sensor's characteristics. Moreover, the MWCNT sheet does not need purification or a complex transfer process to be used as a sensor, making it suitable for practical applications.

  18. Multi-walled carbon nanotubes covalently bonded cellulose composite for chemical vapor sensor

    NASA Astrophysics Data System (ADS)

    Yun, Sungryul; Yang, Sang Yeol; Kim, Jaehwan

    2010-04-01

    A cellulose solution was prepared by dissolving cotton pulp in LiCl/ N,N-Dimethylacetamide (DMAc) solution, and functionalized multi-walled carbon nanotubes (MWCNTs) were reacted with N, N-Carbonyldiimidazoles to obtain MWCNTs-imidazolides. By acylation of cellulose with MWCNTs-imidazolides, MWCNTs were covalently bonded with cellulose chains. Using the product, MWCNTs covalently bonded cellulose composite (M/C) composite was fabricated with mechanical stretching to align MWCNTs with cellulose. Finally, inter-digital comb electrode was formed on the composite via lift-off process. Chemo-electrical properties of the M/C composite in response of absorption of the volatile vapors corresponding to 1-propanol, 1-butanol, methanol and ethanol were investigated. Due to sensitive and reversible expansion/contraction of the M/C composite matrix in response to absorption of each analyte, the M/C composite showed fast and reversible change in chemo-electrical property. The ranking of relative resistance response of the composite was methanol < ethanol < 1-propanol < 1-butanol.

  19. Transport and remobilization of multi-walled carbon nanotubes in porous media during dynamic saturation change

    NASA Astrophysics Data System (ADS)

    Sharma, P.

    2012-04-01

    Nanotechnology is one of the most important technologies in this century and it is evoking a new industrial revolution. Carbon nanotubes (CNTs) are important engineered nanoparticles with unique and beneficial properties. As a result, CNT has been used in a wide range of commercial products including electronics, optical devices and drug delivery leading to their disposal in the natural environment. Literature studies have investigated the mobility of CNTs in saturated porous media under differing physical and chemical conditions. However CNT transport in temporarily changing porous media water content has not been investigated thus far (a common scenario with rainfall/infiltration events in the vadose zone). This study investigated the mobilization of multi-walled CNTs (MCNTs) in repeated wetting and drying cycles with varying flow rates and ionic strength of the inflow solution. Imbibition-drainage-imbibition cycle experiments suggest that MCNTs mobilization increased with increase in flow rates. MCNTs mobilization occurred only with first imbibition events at low ionic strengths however less mobilization happened for higher ionic strength inflow solution in the first imbibition cycle and additional MCNTs were found in the outflow solution in second imbibition cycle, using low ionic strength solution. This observation was likely due to the attachment force between MCNTs and sand surface. Most of the MCNT mobilization occurred during liquid-gas interface movement with less chance of MCNTs to jump the energy barrier at higher ionic strength solution. As a result, less detachment of MCNTs occurred from the sand surface during drainage.

  20. Nanogenerators consisting of direct-grown piezoelectrics on multi-walled carbon nanotubes using flexoelectric effects

    NASA Astrophysics Data System (ADS)

    Han, Jin Kyu; Jeon, Do Hyun; Cho, Sam Yeon; Kang, Sin Wook; Yang, Sun A.; Bu, Sang Don; Myung, Sung; Lim, Jongsun; Choi, Moonkang; Lee, Minbaek; Lee, Min Ku

    2016-07-01

    We report the first attempt to prepare a flexoelectric nanogenerator consisting of direct-grown piezoelectrics on multi-walled carbon nanotubes (mwCNT). Direct-grown piezoelectrics on mwCNTs are formed by a stirring and heating method using a Pb(Zr0.52Ti0.48)O3 (PZT)-mwCNT precursor solution. We studied the unit cell mismatch and strain distribution of epitaxial PZT nanoparticles, and found that lattice strain is relaxed along the growth direction. A PZT-mwCNT nanogenerator was found to produce a peak output voltage of 8.6 V and an output current of 47 nA when a force of 20 N is applied. Direct-grown piezoelectric nanogenerators generate a higher voltage and current than simple mixtures of PZT and CNTs resulting from the stronger connection between PZT crystals and mwCNTs and an enhanced flexoelectric effect caused by the strain gradient. These experiments represent a significant step toward the application of nanogenerators using piezoelectric nanocomposite materials.

  1. 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.

  2. 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.

  3. 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

  4. Development of biofuel cells based on gold nanoparticle decorated multi-walled carbon nanotubes.

    PubMed

    Naruse, Junichi; Hoa, Le Quynh; Sugano, Yasuhito; Ikeuchi, Tomohiko; Yoshikawa, Hiroyuki; Saito, Masato; Tamiya, Eiichi

    2011-12-15

    This study focused on developing the synthesis of Au nanoparticle-decorated functionalized multi-walled carbon nanotubes (Au-NPs/f-MWCNTs) for monosaccharide (bio-fuel) oxidation reactions and practical application in air-biofuel cells. We developed a scalable and straightforward method to synthesize Au-NPs/f-MWCNTs which allow us to control the loading and size of the Au-NPs. The Au-NPs/f-MWCNTs exhibited better catalytic activities and stability than the Au sheet and subsequently resulted in a threefold increase in the power density of the air-glucose fuel cell with an exceptionally high open circuit voltage (~1.3 V). The catalytic efficiency was confirmed by high performance liquid chromatography with the superior of the Au-NPs/f-MWCNTs over a bare gold electrode. In addition, the application of this advanced catalyst to other monosaccharide oxidation reactions figured out that the configuration of -OH groups at C(2) and C(3) of the reactants plays an important role in the initial adsorption process, and thus, affects the required activation energy for further oxidation. The different monosaccharides lead to significantly different fuel cell performances in terms of power density, which coherently corresponds to the difference in the configuration of C(2) and C(3). Because two small air-glucose fuel cells using Au-NPs/f-MWCNTs can run a LED lamp, further applications of other monosaccharides as fuel in biofuel cells for equivalent required power devices may be possible.

  5. 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.

  6. Nanogenerators consisting of direct-grown piezoelectrics on multi-walled carbon nanotubes using flexoelectric effects

    PubMed Central

    Han, Jin Kyu; Jeon, Do Hyun; Cho, Sam Yeon; Kang, Sin Wook; Yang, Sun A.; Bu, Sang Don; Myung, Sung; Lim, Jongsun; Choi, Moonkang; Lee, Minbaek; Lee, Min Ku

    2016-01-01

    We report the first attempt to prepare a flexoelectric nanogenerator consisting of direct-grown piezoelectrics on multi-walled carbon nanotubes (mwCNT). Direct-grown piezoelectrics on mwCNTs are formed by a stirring and heating method using a Pb(Zr0.52Ti0.48)O3 (PZT)-mwCNT precursor solution. We studied the unit cell mismatch and strain distribution of epitaxial PZT nanoparticles, and found that lattice strain is relaxed along the growth direction. A PZT-mwCNT nanogenerator was found to produce a peak output voltage of 8.6 V and an output current of 47 nA when a force of 20 N is applied. Direct-grown piezoelectric nanogenerators generate a higher voltage and current than simple mixtures of PZT and CNTs resulting from the stronger connection between PZT crystals and mwCNTs and an enhanced flexoelectric effect caused by the strain gradient. These experiments represent a significant step toward the application of nanogenerators using piezoelectric nanocomposite materials. PMID:27406631

  7. 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.

  8. [Catalytic wet air oxidation of phenol and aniline over multi-walled carbon nanotubes].

    PubMed

    Li, Xiang; Yang, Shao-xi; Zhu, Wan-peng; Wang, Jian-bing; Wang, Li

    2008-09-01

    Multi-walled carbon nanotubes (MWNTs) without any metal ions were used as the catalyst, and investigated in the CWAO of phenol and aniline in a batch reactor. The structures of the MWNTs were characterized by means of SEM and TEM. It showed that the MWNTs, treated with the mixed acid (HNO3-H2SO4), displayed excellent activity and stability in the CWAO. Under the reaction temperature of 160 degrees C, the total pressure of 2.5 MPa, the initial concentration of 1000 mg/L and loading the catalyst of 1.6 g/L, 100% phenol and 86% COD were removed after 120 min reaction in CWAO of phenol. At the same operating conditions, 83% aniline and 68% COD removals were obtained in the CWAO of aniline solution when the initial concentration of aniline was 2 000 mg/L. The surface functional groups played the important role for the high activity of the MWNTs in CWAO of organic compounds.

  9. Asbestos and multi-walled carbon nanotubes generate distinct oxidative responses in inflammatory cells

    PubMed Central

    Funahashi, Satomi; Okazaki, Yasumasa; Ito, Daiki; Asakawa, Atsushi; Nagai, Hirotaka; Tajima, Masafumi; Toyokuni, Shinya

    2015-01-01

    Asbestos exposure is considered a social burden by causing mesothelioma. Despite the use of synthetic materials, multi-walled carbon nanotubes (MWCNTs) are similar in dimension to asbestos and produce mesothelioma in animals. The role of inflammatory cells in mesothelial carcinogenesis remains unclear. Here, we evaluated the differences in inflammatory cell responses following exposure to these fibrous materials using a luminometer and L-012 (8-amino-5-chloro-7-phenylpyrido[3,4-d]pyridazine-1,4-(2H,3H) dione) to detect reactive oxygen species (ROS). Rat peripheral blood or RAW264.7 cells were used to assess the effects on neutrophils and macrophages, respectively. Crocidolite and amosite induced significant ROS generation by neutrophils with a peak at 10 min, whereas that of chrysotile was ~25% of the crocidolite/amosite response. MWCNTs with different diameters (~15, 50, 115 and 145 nm) and different carcinogenicity did not induce significant ROS in peripheral blood. However, the MWCNTs induced a comparable amount of ROS in RAW264.7 cells to that following asbestos treatment. The peaks for MWCNTs (0.5–1.5 h) were observed earlier than those for asbestos (1–5 h). Apocynin and superoxide dismutase significantly inhibited ROS generation for each fiber, suggesting an involvement of NADPH oxidase and superoxide. Thus, asbestos and MWCNTs induce different oxidative responses in inflammatory cells, indicating the importance of mesothelial cell evaluation for carcinogenesis. PMID:25759516

  10. Enhanced performance of microbial fuel cell with a bacteria/multi-walled carbon nanotube hybrid biofilm

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Liu, Jia; Qu, Youpeng; Zhang, Jian; Zhong, Yingjuan; Feng, Yujie

    2017-09-01

    The biofilm on the anode of a microbial fuel cell (MFC) is a vital component in system, and its formation and characteristic determines the performance of the system. In this study, a bacteria/Multi-Walled Carbon Nanotube (MWCNT) hybrid biofilm is fabricated by effectively inserting the MWCNTs into the anode biofilm via an adsorption-filtration method. This hybrid biofilm has been demonstrated to be an efficient structure for improving an anode biofilm performance. Electrochemical impedance spectroscopy (EIS) results show that the hybrid biofilm takes advantage of the conductivity and structure of MWCNT to enhance the electron transfer and substrate diffusion of the biofilm. With this hybrid biofilm, the current density, power density and coulombic efficiency are increased by 46.2%, 58.8% and 84.6%, respectively, relative to naturally grown biofilm. Furthermore, the start-up time is reduced by 53.8% compared with naturally grown biofilm. The perturbation test demonstrates that this type of hybrid biofilm exhibits strong adsorption ability and enhances the biofilm's resistance to a sudden change of substrate concentration. The superior performance of the hybrid biofilm with MWCNT ;nanowire; matrix compared with naturally grown biofilm demonstrates its great potential for boosting the performance of MFCs.

  11. Fluorescence Spectrometry of the Interaction of Multi-Walled Carbon Nanotubes with Catalase

    NASA Astrophysics Data System (ADS)

    Fan, Y.; Li, Y.; Cai, H.; Li, J.; Miao, J.; Fu, D.; Yang, Q.

    2014-11-01

    The interaction of multi-walled carbon nanotubes (MWCNTs) with catalase is investigated using fluorescence and circular dichroism spectroscopic techniques. The results of the fluorescence experiments suggest that MWCNTs quench the intrinsic fluorescence of catalase via a static quenching mechanism. The circular dichroism spectral results reveal the unfolding of catalase with a significant decrease in the α-helix content in the presence of MWCNTs, which indicates that the conformation of catalase is changed in the binding process, thereby remarkably decreasing its activity. The binding constants and the number of binding sites of the MWCNT to the catalase are calculated at different temperatures. The thermodynamic parameters, such as the changes in free energy (ΔG), enthalpy (ΔH), and entropy (ΔS), are calculated using thermodynamic equations. The fact that all negative values of ΔG, ΔH, and ΔS are obtained suggests that the interaction of the MWCNTs with catalase is spontaneous, and that hydrogen bonding and van der Waals interactions play an important role in the binding process.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27578567

  13. Suspending multi-walled carbon nanotubes by humic acids from a peat soil.

    PubMed

    Zhou, Xinzhe; Shu, Liang; Zhao, Huibin; Guo, Xiaoying; Wang, Xilong; Tao, Shu; Xing, Baoshan

    2012-04-03

    Suspension of the pristine and COOH-substituted multi-walled carbon nanotubes (P- and C-MWCNTs) with different outer diameters (ODs) by humic acids (HAs) from a peat soil was examined. Under shaking condition, MWCNTs were not suspended within 5 d. Without HAs, C-MWCNTs were slightly suspended by sonication within 16 h, but no suspension was observed for the pristine ones (P-MWCNTs). HAs greatly enhanced suspension of both P- and C-MWCNTs. The suspension enhancement was attributed to HA sorption, which increased electrostatic repulsion and steric hindrance between individual MWCNTs. Introduction of O-containing hydrophilic moieties to MWCNTs via HA sorption enhanced the interactions of their surfaces with water through H-bonding. Suspending capability of various MWCNTs on suspended mass concentration basis by four HAs showed inconsistent orders with the increasing or decreasing trend of their ODs. However, the suspended surface area concentrations of both P- and C-MWCNTs by individual HAs consistently followed an order of P8 > P30 > P50, and C8 > C30 > C50 (P and C, respectively, refer to P- and C-MWCNTs, and the numbers represent their ODs). These data implied that MWCNTs with smaller OD could be more strongly suspended by a given HA relative to those with larger OD under sonication condition.

  14. 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 HO2(-). 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), %HO2(-) 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 (HO2(-) 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.

  15. 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.

  16. The decoration of multi-walled carbon nanotubes with nickel oxide nanoparticles using chemical method

    NASA Astrophysics Data System (ADS)

    Sahebian, S.; Zebarjad, S. M.; Vahdati Khaki, J.; Lazzeri, A.

    2016-07-01

    In this paper, nickel oxide (NiO) nanoparticles have been fabricated using wet method and deposited on the surface of multi-walled carbon nanotube (MWCNT). To do so, functional groups were introduced on the surface of MWCNTs by treating with concentrated nitric acid. Nickel oxide nanoparticles were formed on the surface of functionalized MWCNTs by incipient wetness impregnation of nickel nitrate, and the resultant product was calcinated in air atmosphere. Characteristics of the NiO/MWCNT were examined by various techniques, for example, Fourier transform spectroscopy (FTIR), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), thermogravimetric analyzer (TGA), and nitrogen adsorption-desorption isothermal as well as vibrating sample magnetometer (VSM). The FTIR spectra showed that carboxyl and hydroxyl functional groups existed on the surface of MWNTs after modification by concentrated nitric acid. The pattern of XRD indicated that MWNTs and nickel oxide nanoparticles coexisted in the NiO/MWCNT sample. The TEM images revealed that the NiO nanoparticles were distributed on the surface of the MWNTs, with the size ranging from 5 to 60 nm. Thermogravimetric analysis proved that NiO content decorated on MWCNTs was 80 and 15 wt%. The results of the Brunauer-Emmett-Teller (BET) data showed that the slight increment in the specific surface areas and porosities in the presence of the NiO nanoparticles on the surface of CNT.

  17. Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine.

    PubMed

    Deborah, M; Jawahar, A; Mathavan, T; Dhas, M Kumara; Benial, A Milton Franklin

    2015-03-15

    The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (002) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery.

  18. Optimized network of multi-walled carbon nanotubes for chemical sensing

    NASA Astrophysics Data System (ADS)

    Gohier, A.; Chancolon, J.; Chenevier, P.; Porterat, D.; Mayne-L'Hermite, M.; Reynaud, C.

    2011-03-01

    This work reports the design of a resistive gas sensor based on 2D mats of multi-walled carbon nanotubes (MWCNTs) grown by aerosol-assisted chemical vapour deposition. The sensor sensitivity was optimized using chlorine as analyte by tuning both CNT network morphology and CNT electronic properties. Optimized devices, operating at room temperature, have been calibrated over a large range of concentration and are shown to be sensitive down to 27 ppb of chlorine. The as-grown MWCNT response is compared with responses of 2000 °C annealed CNTs, as well as of nitrogen-doped CNTs and CNTs functionalized with polyethyleneimine (PEI). Under chlorine exposure, the resistance decrease of as-grown and annealed CNTs is attributed to charge transfer from chlorine to CNTs and demonstrates their p-type semiconductor behaviour. XPS analysis of CNTs exposed to chlorine shows the presence of chloride species that confirms electron charge transfer from chlorine to CNTs. By contrast, the resistance of nitrogen-doped and PEI functionalized CNTs exposed to chlorine increases, in agreement with their n-type semiconductor nature. The best response is obtained using annealed CNTs and is attributed to their higher degree of crystallinity.

  19. Dynamic synergy of graphitic nanoplatelets and multi-walled carbon nanotubes in polyetherimide nanocomposites

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Sun, L. L.; Caceres, S.; Li, B.; Wood, W.; Perugini, A.; Maguire, R. G.; Zhong, W. H.

    2010-03-01

    Hybridizing graphitic nanoplatelets (GNP) with commercially functionalized multi-walled carbon nanotubes (MWCNTs) in a polyetherimide (PEI) composite at a total loading of 0.5 wt% resulted in considerable improvements in electrical conductivity, thermal conductivity and dynamic mechanical properties, compared to solely GNP or solely MWCNT composites at the same total loading. The results reveal a synergistic interaction between the GNPs and MWCNTs based on GNP protection against fragmentation of the MWCNTs during high power sonication, while still allowing full dispersion of both fillers, by providing a shielding mechanism against MWCNT damage during dispersion processing. A new process for molecular level dispersion of exfoliated GNPs in PEI is also reported. Field emission scanning electron microscopy revealed strong interactions between PEI and the flat surfaces of GNPs and effectively intercalated GNP morphology within the matrix. GNPs alone can also produce excellent electrical conductivity improvements: at 1.0 wt% of GNP, electrical conductivity of the composite increased by 11 orders of magnitude and the percolation threshold was determined to be between 0.5 and 1.0 wt% of GNP.

  20. Multi-walled carbon nanotubes change morpho-functional and GABA characteristics of mouse cortical astrocytes.

    PubMed

    Min, Joo-Ok; Kim, Seong Yeol; Shin, Ueon Sang; Yoon, Bo-Eun

    2015-12-18

    Multi-walled carbon nanotubes (MW-CNTs) have been extensively explored for their possible beneficial use in the nervous system. CNTs have shown to modulate neuronal growth and electrical properties, but its effect that varying length of MW-CNTs on primary astrocyte roles have not been clearly demonstrated yet. We investigate here the effect of MW-CNTs on astrocytic morphology, cell-cell interaction and the distribution of intracellular GABA (gamma-amino butyric acid). Primary cultured cortical astrocytes on MW-CNT-coated glass coverslips grow rounder and make more cell-cell interactions, with many cell processes, compared to astrocytes on poly-D-lysine (PDL) coverslips. In addition, intracellular GABA spreads into the cell processes of astrocytes on MW-CNT coverslips. When this GABA spreads into cell processes from the cell body GABA can be released more easily and in larger quantities compared to astrocytes on PDL coverslips. Our result confirm that MW-CNTs modulate astrocytic morphology, the distribution of astrocytic GABA, cell-cell interactions and the extension of cell processes. CNTs look to be a promising material for use neuroprosthetics such as brain-machine interface technologies.

  1. Gamma (γ)-ray irradiated multi-walled carbon nanotubes (MWCNTs) for hydrogen storage

    NASA Astrophysics Data System (ADS)

    Silambarasan, D.; Surya, V. J.; Iyakutti, K.; Asokan, K.; Vasu, V.; Kawazoe, Y.

    2017-10-01

    A study on hydrogen uptake performance of Gamma (γ)-ray irradiated multi-walled carbon nanotubes (MWCNTs) was conducted. Initially, the MWCNTs was irradiated by γ-rays emitted from 27Co60 source with different doses of 25, 50, 100, 150, and 200 kGy in air at ambient conditions. Irradiation at lower doses of 25 and 50 kGy improves the graphitic order of MWCNTs, but higher doses of 100 and 150 kGy introduces structural imperfection and at very high dose of 200 kGy, the structure becomes distorted. Thermogravimetry (TGA), X-ray diffraction (XRD), Raman spectroscopy, I-V measurements, and Transmission electron microscopy (TEM) confirm the changes in MWCNTs caused by irradiation. Further, the γ-irradiated MWCNTs was hydrogenated and the MWCNTs irradiated at 150 kGy exhibits a considerable hydrogen storage capacity of 1.2 wt.% at 100 °C and ambient pressure, while the MWCNTs irradiated at lower doses does not show any trace of hydrogenation. Raman and elemental analyses provide the evidence for hydrogenation.

  2. Rheological and mechanical properties of polypropylene prepared with multi-walled carbon nanotube masterbatch.

    PubMed

    Shim, Young-Sun; Park, Soo-Jin

    2012-07-01

    In this study, the effects of polypropylene-grafted maleic-anhydride-treated multi-walled carbon nanotubes (PP-MWNTs) on the viscoelastic behaviors and mechanical properties of a polypropylene-(PP)-based composite system were examined. The PP-MWNT/PP composites were prepared via melt mixing with a 3:1 ratio of PP-g-MA and acid-treated MWNTs at 220 degrees C. The surface characteristics of the PP-MWNTs were confirmed via Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). The viscoelastic behavior and mechanical properties of the PP-MWNT/PP composites were confirmed using a rheometer and an ultimate testing machine (UTM). The storage and loss moduli increased with increasing PP-MWNT content. The critical intensity stress factor (K(IC)) of the PP-MWNT/PP composites at high filler loading was also higher than that of the MWNT/PP composites. In conclusion, the viscoelastic behavior and mechanical properties of MWNT/PP can be improved by grafting MWNTs to PP-g-MA.

  3. 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.

  4. 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

  5. A facile approach for imprinting protein on the surface of multi-walled carbon nanotubes.

    PubMed

    Liu, Ren; Sha, Mo; Jiang, Sisi; Luo, Jing; Liu, Xiaoya

    2014-03-01

    This study describes a green, facile and low cost approach for imprinting protein on the surface of multi-walled carbon nanotubes (MWNTs) using papain as the template, dopamine as the functional monomer. By simply mixing MWNTs, dopamine, template protein in weak alkaline aqueous solution, a thin adherent polydopamine (PDA) film imprinted with protein was spontaneously obtained on the surface of MWNTs to produce the imprinted nanomaterials (MWNTs@MIPs). The obtained MWNTs@MIPs were characterized with Fourier transform infrared spectrometer (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The adsorption process of the MWNTs@MIPs towards template protein was investigated in detail. The effects of the concentration of the monomer and template, polymerization time, extraction process were optimized. The prepared MWNTs@MIPs show fast binding kinetics, high binding capacity and acceptable specific recognition behavior towards template proteins. Furthermore, the stability and regeneration were also investigated, which indicated that the MWNTs@MIPs had good reusability. The good recognizing behavior coupled to the low cost and facile one-step preparation make the MWNTs@MIPs attractive for separation and specific protein recognition.

  6. 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

  7. Structural and magnetic characterization of batch-fabricated nickel encapsulated multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zeeshan, M. A.; Shou, K.; Pané, S.; Pellicer, E.; Sort, J.; Sivaraman, K. M.; Baró, M. D.; Nelson, B. J.

    2011-07-01

    We report on the growth and fabrication of Ni-filled multi-walled carbon nanotubes (Ni-MWNTs) with an average diameter of 115 nm and variable length of 400 nm-1 µm. The Ni-MWNTs were grown using template-assisted electrodeposition and low pressure chemical vapor deposition (LPCVD) techniques. Anodized alumina oxide (AAO) templates were fabricated on Si using a current controlled process. This was followed by the electrodeposition of Ni nanowires (NWs) using galvanostatic pulsed current (PC) electrodeposition. Ni NWs served as the catalyst to grow Ni-MWNTs in an atmosphere of H2/C2H2 at a temperature of 700 °C. Time dependent depositions were carried out to understand the diffusion and growth mechanism of Ni-MWNTs. Characterization was carried out using scanning electron microscopy (SEM), focused ion beam (FIB) milling, transmission electron microscopy (TEM), Raman spectroscopy and energy dispersive x-ray spectroscopy (EDX). TEM analysis revealed that the Ni nanowires possess a fcc structure. To understand the effects of the electrodeposition parameters, and also the effects of the high temperatures encountered during MWNT growth on the magnetic properties of the Ni-MWNTs, vibrating sample magnetometer (VSM) measurements were performed. The template-based fabrication method is repeatable, efficient, enables batch fabrication and provides good control on the dimensions of the Ni-MWNTs.

  8. Dispersion characteristics and properties of poly(methyl methacrylate)/multi-walled carbon nanotubes nanocomposites.

    PubMed

    Vaudreuil, Sébastien; Labzour, Asmae; Sinha-Ray, Suprakas; El Mabrouk, Khalil; Bousmina, Mosto

    2007-07-01

    The preparation, characterization, and properties of poly(methyl methacrylate) (PMMA)/multi-walled carbon nanotubes (MWCNTs) nanocomposites are described. Nanocomposites have been prepared by melt-blending in a batch mixer. Both unmodified and surface modified MWCNTs have been used for the nanocomposites preparation. Using both unmodified and modified MWCNTs, the effect of surface modification in nanocomposites is investigated by focusing on three major aspects: dispersion characteristics, mechanical properties, and electrical conductivity measurements. Dispersion of the MWCNTs in the PMMA matrix is examined by scanning and transmission electron microscopy that revealed a homogeneous distribution-dispersion of MWCNTs in the PMMA matrix for both unmodified and modified MWCNTs. Thermomechanical behavior is studied by dynamic mechanical analyzer and results showed a substantial improvement in the mechanical properties of PMMA in conjunction to an increase in the elastic behavior. The tensile properties of neat PMMA moderately improved after nanocomposites preparation with both modified and unmodified MWCNTs, however, electrical conductivity of neat PMMA significantly improved after nanocomposites preparation with 2 wt% unmodified MWCNTs. For example, the through plane conductivity increased from 3.6 x 10(-12) S x cm(-1) for neat PMMA to 3.6 x 10(-9) S x cm(-1) for nanocomposite. The various property measurements have been conducted and results have shown that, in overall, surface modifications have very little or no effect on final properties of neat PMMA.

  9. Multi-walled carbon nanotubes can enhance root elongation of wheat ( Triticum aestivum) plants

    NASA Astrophysics Data System (ADS)

    Wang, Xiuping; Han, Heyou; Liu, Xueqin; Gu, Xiaoxu; Chen, Kun; Lu, Donglian

    2012-06-01

    The potential effects of oxidized multi-walled carbon nanotubes (o-MWCNTs) with a length ranging from 50 to 630 nm on the development and physiology of wheat plants were evaluated by examining their effects on seed germination, root elongation, stem length, and vegetative biomass at a concentration ranging from 10 to 160 μg/mL in the plant. Results indicated that after 7 days of exposure to the o-MWCNTs medium, faster root growth and higher vegetative biomass were observed, but seed germination and stem length did not show any difference as compared with controls. Moreover, a physiological study was conducted at cellular level using a traditional physiological approach to evidence the possible alterations in morphology, the cell length of root zone, and the dehydrogenase activity of seedlings. Transmission electron microscopy images revealed that o-MWCNTs could penetrate the cell wall and enter the cytoplasm after being taken up by roots. The cell length of root zone for the seedlings germinated and grown in the o-MWCNTs (80 μg/mL) medium increased by 1.4-fold and a significant concentration-dependent increase in the dehydrogenase activity for the o-MWCNT-treated wheat seedlings was detected. These findings suggest that o-MWCNTs can significantly promote cell elongation in the root system and increase the dehydrogenase activity, resulting in faster root growth and higher biomass production.

  10. 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.

  11. Synthesis and characterization of processable multi-walled carbon nanotubes-sulfonated polydiphenylamine graft copolymers.

    PubMed

    Lee, Kwang-Pill; Gopalan, Anantha Iyengar; Kim, Kyu Soo; Santhosh, Padmanabhan

    2007-10-01

    Water soluble and processable nanocomposites composed of multi-walled carbon nanotubes (MWNTs) and poly(diphenylamine sulfonic acid) (PDPASA) are synthesized and characterized. Two types of methodologies are adopted. MWNTs are covalently functionalized with 2,5-diaminobenzene sulfonic acid (DABSA) and further in situ polymerized with diphenylamine-4-sulfonic acid (DPASA). This results in the formation of nanocomposites, MWNT(DABSA)-g-PDPASA, in which PDPASA is presented as the graft chains onto MWNTs. In another approach, DPASA is in situ polymerized in presence of unfunctionalized MWNTs, results in a nanocomposite in which MWNTs are present as entrapped mass in PDPASA matrix. Both nanocomposites are found to be water soluble and can form free standing films. The conductivity of MWNT(DABSA)-g-PDPASA and MWNT/PDPASA is found to be 1.25 mS x cm(-1) and 0.65 mS x cm(-1), respectively, which is higher than that of pristine PDPASA (0.25 x 10(-5) S x cm(-1)). The nanocomposites are characterized for their structure, morphology, optical and thermal properties.

  12. Growth of spin-capable multi-walled carbon nanotubes and flexible transparent sheet films.

    PubMed

    Jang, Hoon-Sik; Jeon, Sang Koo; Kwon, Oh-Heon; Lee, Seek Cheol; Kim, Chang Soo; Nahm, Seung Hoon

    2012-04-01

    Iron-catalyzed spin-capable multi-walled carbon nanotubes (MWCNTs) were grown on a SiO2 wafer by chemical vapor deposition, which was carried out at 780 degrees C using C2H2 and H2 gases. We fabricated a flexible transparent film using the spun MWCNTs. The MWCNT sheets were produced by being continuously pulled out from well-aligned MWCNTs grown on a substrate. The MWCNT sheet films were manufactured by simply carrying out direct coating on a flexible film or glass. The thickness of the sheet film decreased remarkably when alcohol was sprayed on the surface of the sheet. The alcohol spraying increased the transmittance and decreased the electrical resistance of the MWCNT sheet films. The sheets obtained after alcohol spraying had a resistance of -699 omega and a transmittance of 81%-85%. The MWCNT sheet films were heated by applying direct current. The transparent heaters showed a rapid thermal response and uniform distribution of temperature. In addition, we tested the field emission of the sheet films. The sheet films showed a turn-on voltage of -1.45 V/microm during field emission.

  13. Hydrophilic modification of neural microelectrode arrays based on multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chen, Chang-Hsiao; Su, Huan-Chieh; Chuang, Shih-Chang; Yen, Shiang-Jie; Chen, Yung-Chan; Lee, Yu-Tao; Chen, Hsin; Yew, Tri-Rung; Chang, Yen-Chung; Yeh, Shih-Rung; Yao, Da-Jeng

    2010-12-01

    To decrease the impedance of microelectrode arrays, for neuroscience applications we have fabricated and tested MEA based on multi-walled carbon nanotubes. With decreasing physical size of a microelectrode, its impedance increases and charge-transfer capability decreases. To decrease the impedance, the effective surface area of the electrode must generally be increased. We explored the effect of plasma treatment on the surface wettability of MWCNT. With a steam-plasma treatment the surface of MWCNT becomes converted from superhydrophobic to superhydrophilic; this hydrophilic property is attributed to -OH bonding on the surface of MWCNT. We reported the synthesis at 400 °C of MWCNT on nickel-titanium multilayered metal catalysts by thermal chemical vapor deposition. Applying plasma with a power less than 25 W for 10 s improved the electrochemical and biological properties, and circumvented the limitation of the surface reverting to a hydrophobic condition; a hydrophilic state is maintained for at least one month. The MEA was used to record neural signals of a lateral giant cell from an American crayfish. The response amplitude of the action potential was about 275 µV with 1 ms period; the recorded data had a ratio of signal to noise up to 40.12 dB. The improved performance of the electrode makes feasible the separation of neural signals and the recognition of their distinct shapes. With further development the rapid treatment will be useful for long-term recording applications.

  14. Temperature-Compensated Force/Pressure Sensor Based on Multi-Walled Carbon Nanotube Epoxy Composites

    PubMed Central

    Dinh, Nghia Trong; Kanoun, Olfa

    2015-01-01

    In this study, we propose a multi-walled carbon nanotube epoxy composite sensor for force and pressure sensing in the range of 50 N–2 kN. A manufacturing procedure, including material preparation and deposition techniques, is proposed. The electrode dimensions and the layer thickness were optimized by the finite element method. Temperature compensation is realized by four nanocomposites elements, where only two elements are exposed to the measurand. In order to investigate the influence of the filler contents, samples with different compositions were prepared and investigated. Additionally, the specimens are characterized by cyclical and stepped force/pressure loads or at defined temperatures. The results show that the choice of the filler content should meet a compromise between sensitivity, temperature influence and noise behavior. At constant temperature, a force of at least 50 N can be resolved. The measurement error due to the temperature influence is 150 N in a temperature range of −20°C−50°C. PMID:25985160

  15. Multi-Wall Carbon Nanotubes as Lithium Nanopipettes and SPM Probes

    NASA Astrophysics Data System (ADS)

    Larson, Jonathan; Bharath, Satyaveda; Cullen, William; Reutt-Robey, Janice

    2014-03-01

    A multi-walled carbon nanotube (MWCNT) - terminated SPM cantilever, was utilized to perform nanolithography and surface diffusion measurements on a thin film of vapor-deposited lithium atop a silicon (111) substrate under ultra-high vacuum conditions. In these investigations the MWCNT tip was shown to act as both a lithium nanopipette and a probe for non-contact atomic force microscopy (NC-AFM) measurements. With the application of appropriate bias conditions, the MWCNT could site-selectively extract (expel) nano-scale amounts of lithium from (to) the sample surface. Depressions, mounds, and spikes were generated on the surface in this way and were azimuthally symmetric about the selected point of pipetting. Following lithium transfer to/from the substrate, the MWCNT pipette-induced features were sequentially imaged with NC-AFM using the MWCNT as the probe. Vacancy pits of ca. 300 nm diameter and 1.5 nm depth were observed to decay on a timescale of hours at room temperature, through diffusion-limited decay processes. A continuum model was utilized to simulate the island decay rates, and the lithium surface diffusion coefficient of D =7.5 (+/-1.3)*10-15 cm2/s was extracted. U.S. Department of Energy Award Number DESC0001160.

  16. Immobilization of Platinum Nanoparticles on 3,4-diaminobenzoyl-Functionalized Multi-Walled Carbon Nanotube and its Electrocatalytic Activity

    DTIC Science & Technology

    2012-01-01

    Published online: 26 January 2012 Springer Science+Business Media B.V. 2012 Abstract Multi-walled carbon nanotubes (MWCNTs) are functionalized at the...electroless metal deposition process (Li et al. 1998), and assembly of CNT–metal nanoparticle hybrids using biointerfaces ( Kim et al. 2010). Among...Laboratory, Wright-Patterson AFB, Dayton, OH 45433, USA 123 J Nanopart Res ( 2012 ) 14:704 DOI 10.1007/s11051-011-0704-5 Report Documentation Page Form

  17. 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

    2017-08-07

    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.

  18. 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.

  19. 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

  20. Electrochemical detection and degradation of ibuprofen from water on multi-walled carbon nanotubes-epoxy composite electrode.

    PubMed

    Motoc, Sorina; Remes, Adriana; Pop, Aniela; Manea, Florica; Schoonman, Joop

    2013-04-01

    This work describes the electrochemical behaviour of ibuprofen on two types of multi-walled carbon nanotubes based composite electrodes, i.e., multi-walled carbon nanotubes-epoxy (MWCNT) and silver-modified zeolite-multi-walled carbon nanotubes-epoxy (AgZMWCNT) composites electrodes. The composite electrodes were obtained using two-roll mill procedure. SEM images of surfaces of the composites revealed a homogeneous distribution of the composite components within the epoxy matrix. AgZMWCNT composite electrode exhibited the better electrical conductivity and larger electroactive surface area. The electrochemical determination of ibuprofen (IBP) was achieved using AgZMWCNT by cyclic voltammetry, differential-pulsed voltammetry, square-wave voltammetry and chronoamperometry. The IBP degradation occurred on both composite electrodes under controlled electrolysis at 1.2 and 1.75 V vs. Ag/AgCl, and IBP concentration was determined comparatively by differential-pulsed voltammetry, under optimized conditions using AgZMWCNT electrode and UV-Vis spectrophotometry methods to determine the IBP degradation performance for each electrode. AgZMWCNT electrode exhibited a dual character allowing a double application in IBP degradation process and its control.

  1. Glassy carbon/multi walled carbon nanotube/cadmium sulphide photoanode for light energy storage in vanadium photoelectrochemical cell

    NASA Astrophysics Data System (ADS)

    Peimanifard, Zahra; Rashid-Nadimi, Sahar

    2015-12-01

    The aim of this study is utilizing the artificial photosynthesis, which is an attractive and challenging theme in the photoelectrocatalytic water splitting, to charge the vanadium redox flow battery (VRFB). In this work multi walled carbon nanotube/cadmium sulphide hybrid is employed as a photoanode material to oxidize VO2+ to VO2+ for charging the positive vanadium redox flow battery's half-cell. Characterization studies are also described using the scanning electron microscopic-energy-dispersive X-ray spectroscopy (SEM-EDS), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and UV-Visible methods. The phtoelectrochemical performance is characterized by cyclic voltammetry and chronoamperometry. Applied bias photon-to-current efficiency (ABPE) is achieved for both two and three-electrode configurations. The glassy carbon/multi walled carbon nanotube/cadmium sulphide yields high maximum ABPE of 2.6% and 2.12% in three and two-electrode setups, respectively. These results provide a useful guideline in designing photoelectrochemical cells for charging the vanadium redox flow batteries by sunlight as a low cost, free and abundant energy source, which does not rely on an external power input.

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

    PubMed

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

    2013-06-25

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

  3. The effect of ultrasonic processing of multi-wall carbon nanotubes on properties of elastomeric compositions on the basis of synthetic isoprene rubber

    NASA Astrophysics Data System (ADS)

    Mitryaeva, N. S.; Myshlyavtsev, A. V.; Akimenko, S. S.

    2017-08-01

    The paper studies the effect of ultrasonic processing on the vulcanizing, physical, mechanical and electrophysical properties of elastomeric compositions based on synthetic isoprene rubber. Microscopic studies of multi-wall carbon nanotubes samples before and after ultrasonic processing are carried out. Due to the research, the applied ultrasonic processing method provides splitting of bundles formed from multi-wall carbon nanotubes. This results in elastomeric material with increased strength and high electrical conductivity with a low concentration of nanofiller.

  4. 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.; Rong, L.; Hsiao, B.

    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 sizes 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.

  5. Preparation and characterization of electrospun core sheath nanofibers from multi-walled carbon nanotubes and poly(vinyl pyrrolidone).

    PubMed

    Miao, Jianjun; Miyauchi, Minoru; Dordick, Jonathan S; Linhardt, Robert J

    2012-03-01

    Electrospinning is a versatile technique to prepare polymer fibers in nano to micrometer size ranges using very high electrostatic fields. Electrospun nanofibers with tunable porosity and high specific surface area have various applications, including chromatographic supports for protein separation, biomedical devices, tissue engineering and drug delivery matrices, and as key components in solar cells and supercapacitors. Unspinnable materials such as nanoparticles, nanorods, nanotubes or rigid conducting polymers can also be electrospun into fibers through co-axial electrospinning. In this study, we have prepared core-sheath nanofibers utilizing co-axial electrospinning. The core portion of these electrospun fibers consists of multi-walled carbon nanotubes and the sheath portion is poly(vinyl pyrrolidone) (PVP). Various morphologies were obtained by changing both core and sheath solution concentrations. The core-sheath nanofibers were characterized by scanning electron microscopy and transmission electron microscopy, to confirm core-sheath morphology, thermogravimetric analysis, and mechanical strength testing. The electrical conductivity of the surfaces of poly(vinyl pyrrolidone) fibers and poly(vinyl pyrrolidone)-multi-walled nanotube fibers were both 10(-15) S/m. The highest bulk conductivity observed for the poly(vinyl pyrrolidone)-multi-walled nanotube fibers was 1.2 x 10(-3) S/m.

  6. Fabrication and Characterization of Waterborne Multi-wall Carbon Nanotube Paints

    NASA Astrophysics Data System (ADS)

    Dowty, Heather; Wang, Chyi-Shan

    2005-04-01

    The fabrication of water-borne polyurethane nanocomposites containing multi-wall nanotubes has presented a significant technological challenge to those in the polymer community. Such conductive polyurethanes are of great interest to the paint and coatings industry for use in electrical grounding and shielding. Currently, these materials are formed by strong acidic reflux of the nanotubes and subsequent dispersal in the polymer matrix. This treatment can result in significant shortening of the tubes and degradation of the resulting mechanical and electrical transport properties. Here we present an alternate technique in which various conductive and non-conductive water-soluble polymers are physi-adsorbed to the surface of the nanotube. These interactions with the nanotubes result in highly uniform suspensions of water-based urethane coatings and bulk materials. We will examine the polymer chemistry and morphologies of these nanostructured materials and the resulting thermal, electrical and mechanical properties.

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

    SciTech Connect

    Lee, Min-Sang; Park, Soo-Jin

    2015-03-15

    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 CO{sub 2} were investigated using CO{sub 2} adsorption–desorption isotherms at 298 K and thermogravimetric analysis under the flue gas condition (15% CO{sub 2}/85% N{sub 2}). The results obtained in this study indicate that CO{sub 2} adsorption increases after impregnation of PEI. The increase in CO{sub 2} capture was attributed to the affinity between CO{sub 2} and the amine groups. CO{sub 2} adsorption–desorption experiments, which were repeated five times, also showed that the prepared adsorbents have excellent regeneration properties. - Graphical abstract: Fabrication and CO{sub 2} adsorption process of the S-MWCNTs impregnated with PEI. - Highlights: • Silica coated-MWCNT impregnated with PEI was synthesized. • Amine groups of PEI gave CO{sub 2} affinity sites on MWCNT surfaces. • The S-MWCNT/PEI(50) exhibited the highest CO{sub 2} adsorption capacity.

  8. Improved dispersion method of multi-wall carbon nanotube for inhalation toxicity studies of experimental animals.

    PubMed

    Taquahashi, Yuhji; Ogawa, Yukio; Takagi, Atsuya; Tsuji, Masaki; Morita, Koichi; Kanno, Jun

    2013-01-01

    A multi-wall carbon nanotube (MWCNT) product Mitsui MWNT-7 is a mixture of dispersed single fibers and their agglomerates/aggregates. In rodents, installation of such mixture induces inflammatory lesions triggered predominantly by the aggregates/agglomerates at the level of terminal bronchiole of the lungs. In human, however, pulmonary toxicity induced by dispersed single fibers that reached the lung alveoli is most important to assess. Therefore, a method to generate aerosol predominantly consisting of dispersed single fibers without changing their length and width is needed for inhalation studies. Here, we report a method (designated as Taquann method) to effectively remove the aggregate/agglomerates and enrich the well-dispersed singler fibers in dry state without dispersant and without changing the length and width distribution of the single fibers. This method is base on two major concept; liquid-phase fine filtration and critical point drying to avoid re-aggregation by surface tension. MWNT-7 was suspended in Tert-butyl alcohol, freeze-and-thawed, filtered by a vibrating 25 µm mesh Metallic Sieve, snap-frozen by liquid nitrogen, and vacuum-sublimated (an alternative method to carbon dioxide critical point drying). A newly designed direct injection system generated well-dispersed aerosol in an inhalation chamber. The lung of mice exposed to the aerosol contained single fibers with a length distribution similar to the original and the Taquann-treated sample. Taquann method utilizes inexpensive materials and equipments mostly found in common biological laboratories, and prepares dry powder ready to make well-dispersed aerosol. This method and the chamber with direct injection system would facilitate the inhalation toxicity studies more relevant to human exposure.

  9. Health surveillance study of workers who manufacture multi-walled carbon nanotubes.

    PubMed

    Lee, Jong Seong; Choi, Young Chul; Shin, Jae Hoon; Lee, Ji Hyun; Lee, Yurim; Park, So Young; Baek, Jin Ee; Park, Jung Duck; Ahn, Kangho; Yu, Il Je

    2015-01-01

    While many in vivo and in vitro toxicology studies of multi-walled carbon nanotubes (MWCNTs) have already indicated that exposure to MWCNTs can potentially induce health effects in humans, the actual health effects of MWCNTs among exposed workers are not yet known. Moreover, the levels of exposure and internal doses of MWCNTs are becoming more and more important for estimating the health effects resulting from exposure to MWCNTs. However, information on biomonitoring and exposure to MWCNTs remains limited. Therefore, the authors conducted a health surveillance study in a workplace that manufactures MWCNTs, including assessment of the personal and area exposure levels to MWCNTs, a walk-through evaluation of the manufacturing process, and collection of blood and exhaled breath condensates (EBCs) from the MWCNT manufacturing and office workers. In addition, a pulmonary function test was also conducted on the MWCNT manufacturing workers (9) and office workers (4). The worker exposure to elemental carbon was found to be 6.2-9.3 μg/m(3) in the personal samplings and 5.5-7.3 μg/m(3) in the area samplings. Notwithstanding, the workers exhibited a normal range of hematology and blood biochemistry values and normal lung function parameters. When analyzing the EBCs, the malondialdehyde (MDA), 4-hydroxy-2-hexenal (4-HHE) and n-hexanal levels in the MWCNT manufacturing workers were significantly higher than those in the office workers. The MDA and n-hexanal levels were also significantly correlated with the blood molybdenum concentration, suggesting MDA, n-hexanal and molybdenum as useful biomarkers of MWCNT exposure.

  10. 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.

  11. Voltammetric oxidation and determination of cinnarizine at glassy carbon electrode modified with multi-walled carbon nanotubes.

    PubMed

    Hegde, Rajesh N; Hosamani, Ragunatharaddi R; Nandibewoor, Sharanappa T

    2009-09-01

    The voltammetric oxidation of cinnarizine was investigated. In pH 2.5 Britton-Robinson buffer, cinnarizine shows an irreversible oxidation peak at about 1.20 V at a multi-walled carbon nanotube (MWCNT)-modified glassy carbon electrode. The cyclic voltammetric results indicate that MWCNT-modified glassy carbon electrode can remarkably enhance electrocatalytic activity towards the oxidation of cinnarizine. The electrocatalytic behavior was further exploited as a sensitive detection scheme for the cinnarizine determination by differential-pulse voltammetry. Under optimized conditions, the concentration range and detection limit are 9.0x10(-8) to 6.0x10(-6) M and 2.58x10(-9) M, respectively for cinnarizine. The proposed method was successfully applied to cinnarizine determination in pharmaceutical samples. The analytical performance of this sensor has been evaluated for the detection of analyte in urine as a real sample.

  12. 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.

  13. Quasi-QSAR for mutagenic potential of multi-walled carbon-nanotubes.

    PubMed

    Toropov, Andrey A; Toropova, Alla P

    2015-04-01

    Available on the Internet, the CORAL software (http://www.insilico.eu/coral) has been used to build up quasi-quantitative structure-activity relationships (quasi-QSAR) for prediction of mutagenic potential of multi-walled carbon-nanotubes (MWCNTs). In contrast with the previous models built up by CORAL which were based on representation of the molecular structure by simplified molecular input-line entry system (SMILES) the quasi-QSARs based on the representation of conditions (not on the molecular structure) such as concentration, presence (absence) S9 mix, the using (or without the using) of preincubation were encoded by so-called quasi-SMILES. The statistical characteristics of these models (quasi-QSARs) for three random splits into the visible training set and test set and invisible validation set are the following: (i) split 1: n=13, r(2)=0.8037, q(2)=0.7260, s=0.033, F=45 (training set); n=5, r(2)=0.9102, s=0.071 (test set); n=6, r(2)=0.7627, s=0.044 (validation set); (ii) split 2: n=13, r(2)=0.6446, q(2)=0.4733, s=0.045, F=20 (training set); n=5, r(2)=0.6785, s=0.054 (test set); n=6, r(2)=0.9593, s=0.032 (validation set); and (iii) n=14, r(2)=0.8087, q(2)=0.6975, s=0.026, F=51 (training set); n=5, r(2)=0.9453, s=0.074 (test set); n=5, r(2)=0.8951, s=0.052 (validation set). Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Influence of the pore size in multi-walled carbon nanotubes on the hydrogen storage behaviors

    SciTech Connect

    Lee, Seul-Yi; Park, Soo-Jin

    2012-10-15

    Activated multi-walled carbon nanotubes (A-MWCNTs) were prepared using a chemical activation method to obtain well-developed pore structures for use as hydrogen storage materials. The microstructure and crystallinity of the A-MWCNTs were evaluated by X-ray diffraction and Fourier transform Raman spectroscopy. The textural properties of the A-MWCNTs were investigated by nitrogen gas sorption analysis at 77 K. The hydrogen storage capacity of the A-MWCNTs was evaluated at 77 K and 1 bar. The results showed that the specific surface area of the MWCNTs increased from 327 to 495 m{sup 2}/g as the activation temperature was increased. The highest hydrogen storage capacity was observed in the A-MWCNTs sample activated at 900 Degree-Sign C (0.54 wt%). This was attributed to it having the narrowest microporosity, which is a factor closely related to the hydrogen storage capacity. This shows that the hydrogen storage behaviors depend on the pore volume. Although a high pore volume is desirable for hydrogen storage, it is also severely affected if the pore size in the A-MWCNTs for the hydrogen molecules is suitable for creating the activation process. Highlights: Black-Right-Pointing-Pointer The AT-800 and AT-900 samples were prepared by a chemical activation method at activation temperature of 800 and 900 Degree-Sign C, respectively. Black-Right-Pointing-Pointer The AT-900 sample has the narrowest peak in comparison with the AT-800 sample, resulting from the overlap of the two peaks (Peak I and Peak II). Black-Right-Pointing-Pointer This overlapping effect is due to the newly created micropores or shrinkages of pores in Peak II. So, these determining characteristics are essential for designing materials that are suitable for molecular hydrogen storage.

  15. 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.

  16. Dual functional nisin-multi-walled carbon nanotubes coated filters for bacterial capture and inactivation.

    PubMed

    Dong, Xiuli; Yang, Liju

    2015-01-01

    Removal of pathogens from water is one way to prevent waterborne illness. In this paper, we developed dual functional carbon nanotube (CNT) modified filters for bacterial capture and inactivation, utilizing multi-walled CNTs (MWCNTs) to coat on commercially available filters and making use of the exceptional adsorption property of CNTs to adsorb a natural antimicrobial peptide-nisin on it. Two types of MWCNTs with different outer layer diameters were used (MWCNTs1: <8 nm in diameter; MWCNTs2: 10-20 nm in diameter). The thickness of MWCNT layers, surface morphology, and surface hydrophobicity of both types of MWCNT coated filters were characterized. The MWCNT coating on filters significantly increased the surface hydrophobicity. The absorption of nisin and the capture of bacterial pathogens were correlated with increased surface hydrophobicity. The MWCNTs1 and MWCNTs2 filters with 1.5 mg MWCNTs loading captured 2.44 and 3.88 log of cells, respectively, from aqueous solutions containing a total of ~10(6) CFU/mL cells. Nisin deposit at the amount of 0.5 mg on the surfaces of MWCNT filters significantly reduced the viability of captured B. anthracis cells by 95.71-97.19 %, and inhibited the metabolic activities of the captured cells by approximately 98.3 %. The results demonstrated that the MWCNT-nisin filters achieved dual functions in bacterial pathogen capture and inhibition in one single filtration step, which is potentially applicable in removing undesired microorganisms from water sources and inhibiting captured Gram positive bacteria activities.

  17. 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.

  18. Synthesis of hydroxyapatite/multi-walled carbon nanotubes for the removal of fluoride ions from solution

    NASA Astrophysics Data System (ADS)

    Ruan, Zhongyuan; Tian, Yaxi; Ruan, Jifu; Cui, Guijia; Iqbal, Kanwal; Iqbal, Anam; Ye, Herui; Yang, Zhangzhong; Yan, Shiqiang

    2017-08-01

    A novel composite material, hydroxyapatite (HA)-multi-walled carbon nanotubes (MWCNTs), was prepared using a simple in-situ sol-gel method, and was used for the first time to remove fluoride from water. The novel HA-MWCNTs were characterized using TEM, FT-IR, BET and XRD analysis. The TEM and SAED results revealed that the MWCNTs were uniformly encapsulated by hydroxyapatite nanoparticles. The synthesized HA-MWCNTs had a high specific surface area (180.504 m2 g-1), with an average pore width (14.607 nm) and pore volume (0.774 cm3 g-1), which produced a defluoridation capacity (DC) of 30.22 mgF- g-1. This value was greater than unmodified hydroxyapatite (HA), which exhibited a larger specific surface area (172.233 m2 g-1) and an excellent DC of 17.80 mgF- g-1. A number of pertinent parameters that could affect the defluoridation performance of the HA/MWCNTs including weight ratios of the two key materials, solution pH and competing anions were carefully and comprehensively examined. It was found that the adsorption results followed the Langmuir and Freundlich isotherm model, and the sorption kinetics of the F- appeared to exhibit a pseudo second order. Moreover, the adsorption reaction was spontaneous and endothermic and appeared to exhibit a higher initial adsorption rate. This reaction appeared to occur result from both anion exchange and electrostatic interactions. When the HA-MWCNTs (MH6) were at an adsorbent dose of 2.0 g L-1, they were able to decrease the fluoride concentration of actual nuclear industry wastewater from 8.79 mg L-1 to about 0.25 mg L-1 (97.15% removal efficiency). The experimental results of this study showed that the HA-MWCNTs composites have application potential for the removal of fluoride ions from wastewater.

  19. Engineering Multi-Walled Carbon Nanotube Therapeutic Bionanofluids to Selectively Target Papillary Thyroid Cancer Cells

    PubMed Central

    Paliouras, Miltiadis; Mitmaker, Elliot J.; Trifiro, Mark A.

    2016-01-01

    Background The incidence of papillary thyroid carcinoma (PTC) has risen steadily over the past few decades as well as the recurrence rates. It has been proposed that targeted ablative physical therapy could be a therapeutic modality in thyroid cancer. Targeted bio-affinity functionalized multi-walled carbon nanotubes (BioNanofluid) act locally, to efficiently convert external light energy to heat thereby specifically killing cancer cells. This may represent a promising new cancer therapeutic modality, advancing beyond conventional laser ablation and other nanoparticle approaches. Methods Thyroid Stimulating Hormone Receptor (TSHR) was selected as a target for PTC cells, due to its wide expression. Either TSHR antibodies or Thyrogen or purified TSH (Thyrotropin) were chemically conjugated to our functionalized Bionanofluid. A diode laser system (532 nm) was used to illuminate a PTC cell line for set exposure times. Cell death was assessed using Trypan Blue staining. Results TSHR-targeted BioNanofluids were capable of selectively ablating BCPAP, a TSHR-positive PTC cell line, while not TSHR-null NSC-34 cells. We determined that a 2:1 BCPAP cell:α-TSHR-BioNanofluid conjugate ratio and a 30 second laser exposure killed approximately 60% of the BCPAP cells, while 65% and >70% of cells were ablated using Thyrotropin- and Thyrogen-BioNanofluid conjugates, respectively. Furthermore, minimal non-targeted killing was observed using selective controls. Conclusion A BioNanofluid platform offering a potential therapeutic path for papillary thyroid cancer has been investigated, with our in vitro results suggesting the development of a potent and rapid method of selective cancer cell killing. Therefore, BioNanofluid treatment emphasizes the need for new technology to treat patients with local recurrence and metastatic disease who are currently undergoing either re-operative neck explorations, repeated administration of radioactive iodine and as a last resort external beam

  20. Uptake and cytotoxic effects of multi-walled carbon nanotubes in human bronchial epithelial cells

    SciTech Connect

    Hirano, Seishiro; Fujitani, Yuji; Furuyama, Akiko; Kanno, Sanae

    2010-11-15

    Carbon nanotubes (CNT) are cytotoxic to several cell types. However, the mechanism of CNT toxicity has not been fully studied, and dosimetric analyses of CNT in the cell culture system are lacking. Here, we describe a novel, high throughput method to measure cellular uptake of CNT using turbimetry. BEAS-2B, a human bronchial epithelial cell line, was used to investigate cellular uptake, cytotoxicity, and inflammatory effects of multi-walled CNT (MWCNT). The cytotoxicity of MWCNT was higher than that of crocidolite asbestos in BEAS-2B cells. The IC{sub 50} of MWCNT was 12 {mu}g/ml, whereas that of asbestos (crocidolite) was 678 {mu}g/ml. Over the course of 5 to 8 h, BEAS-2B cells took up 17-18% of the MWCNT when they were added to the culture medium at a concentration of 10 {mu}g/ml. BEAS-2B cells were exposed to 2, 5, or 10 {mu}g/ml of MWCNT, and total RNA was extracted for cytokine cDNA primer array assays. The culture supernatant was collected for cytokine antibody array assays. Cytokines IL-6 and IL-8 increased in a dose dependent manner at both the mRNA and protein levels. Migration inhibitory factor (MIF) also increased in the culture supernatant in response to MWCNT. A phosphokinase array study using lysates from BEAS-2B cells exposed to MWCNT indicated that phosphorylation of p38, ERK1, and HSP27 increased significantly in response to MWCNT. Results from a reporter gene assays using the NF-{kappa}B or AP-1 promoter linked to the luciferase gene in transiently transfected CHO-KI cells revealed that NF-{kappa}B was activated following MWCNT exposure, while AP-1 was not changed. Collectively, MWCNT activated NF-{kappa}B, enhanced phosphorylation of MAP kinase pathway components, and increased production of proinflammatory cytokines in human bronchial epithelial cells.

  1. Multi-walled carbon nanotubes injure the plasma membrane of macrophages

    SciTech Connect

    Hirano, Seishiro Kanno, Sanae; Furuyama, Akiko

    2008-10-15

    Carbon nanotubes (CNTs) are emerging nanotechnology materials which are likely to be mass-produced in the near future. However, prior to mass-production, certain health-related concerns should first be addressed. For example, when inhaled, the thin-fibrous shape and the biopersistent characteristics of CNTs may cause pulmonary diseases, in a manner similar to asbestos. In the present study, mouse macrophages (J774.1) were exposed to highly-purified multi-walled CNTs (MWCNTs, 67 nm) or to UICC crocidolite in order to evaluate the toxicity of these nano-size fibers. The cytotoxicity of MWCNTs was found to be higher than that of crocidolite. The toxic effect of MWCNTs was not affected by N-acetylcysteine, an antioxidant, or buthionine sulfoximine, a glutathione synthesis inhibitor. cDNA microarray analyses suggested that the cytotoxicity of MWCNTs could not be explained satisfactorily by either an increase or decrease of gene expression, although mRNA levels of some cytokines were slightly increased by MWCNTs. Moreover, MWCNTs did not significantly activate either MAP kinases such as ERK, JNK and p38, nor common apoptosis pathways such as caspase 3 and PARP. Electron microscopic studies indicated that MWCNTs associate with the plasma membrane of macrophages and disrupt the integrity of the membrane. Several proteins were found to adsorb onto MWCNTs when MWCNT-exposed macrophages were gently lysed. One of these proteins was macrophage receptor with collagenous structure (MARCO). MARCO-transfected CHO-K1 cells associated with MWCNTs more rapidly than mock-transfected cells. These results indicate that MWCNTs probably trigger cytotoxic effects in phagocytotic cells by reacting with MARCO on the plasma membrane and rupturing the plasma membrane.

  2. Multi-walled carbon nanotubes induce cytotoxicity and genotoxicity in human lung epithelial cells.

    PubMed

    Cavallo, Delia; Fanizza, Carla; Ursini, Cinzia Lucia; Casciardi, Stefano; Paba, Emilia; Ciervo, Aureliano; Fresegna, Anna Maria; Maiello, Raffaele; Marcelloni, Anna Maria; Buresti, Giuliana; Tombolini, Francesca; Bellucci, Stefano; Iavicoli, Sergio

    2012-06-01

    The increasing use of nanomaterials in consumer products highlights the importance of understanding their potential toxic effects. We evaluated cytotoxic and genotoxic/oxidative effects induced by commercial multi-walled carbon nanotubes (MWCNTs) on human lung epithelial (A549) cells treated with 5, 10, 40 and 100 µg ml⁻¹ for different exposure times. Scanning electron microscopy (SEM) analysis, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] and lactate dehydrogenase (LDH) assays were performed to evaluate cytotoxicity. Fpg-modified comet assay was used to evaluate direct-oxidative DNA damage. LDH leakage was detected after 2, 4 and 24 h of exposure and viability reduction was revealed after 24 h. SEM analysis, performed after 4 and 24 h exposure, showed cell surface changes such as lower microvilli density, microvilli structure modifications and the presence of holes in plasma membrane. We found an induction of direct DNA damage after each exposure time and at all concentrations, statistically significant at 10 and 40 µg ml⁻¹ after 2 h, at 5, 10, 100 µg ml⁻¹ after 4 h and at 10 µg ml⁻¹ after 24 h exposure. However, oxidative DNA damage was not found. The results showed an induction of early cytotoxic effects such as loss of membrane integrity, surface morphological changes and MWCNT agglomerate entrance at all concentrations. We also demonstrated the ability of MWCNTs to induce early genotoxicity. This study emphasizes the suitability of our approach to evaluating simultaneously the early response of the cell membrane and DNA to different MWCNT concentrations and exposure times in cells of target organ. The findings contribute to elucidation of the mechanism by which MWCNTs cause toxic effects in an in vitro experimental model.

  3. Hydroxyapatite reinforced with multi-walled carbon nanotubes and bovine serum albumin for bone substitute applications

    NASA Astrophysics Data System (ADS)

    Gholami, Fatemeh; Noor, Ahmad-Fauzi Mohd

    2016-12-01

    The similarity of the chemical composition of HA to the mineral phase of bone and its excellent biocompatibility meets the requirement of materials designed for bone substitute purpose. The application of HA in load bearing devices is limited by its poor mechanical properties. CNTs with outstanding stiffness, strength, combined with their small size and large interfacial area, suggest that they may have great potential as a reinforcing agent for HA. This work aims to develop the Hydroxyapatite/Multi-walled Carbon Nanotubes/Bovine Serum Albumin (HA/MWCNTs/BSA) composites with different types of MWCNTs including hydroxylated and carboxylated MWCNTs (MWCNTs-OH, MWCNTs-COOH), and evaluation of mechanical strength and in vitro cellular response of developed composites. HA powder was mixed with de-ionized water, 15 wt.% BSA, and 0.5 wt.% of different MWCNTs* (> 95%), MWCNTs (> 99.9%), MWCNTs-OH (> 99.9%), MWCNTs-COOH (> 99.9%) to produce composites. Among all developed composites, the HA/MWCNTs-COOH/BSA shows the highest compressive strength (29.57 MPa). The cytotoxic effect of HA/MWCNTs-COOH/BSA with different concentrations (6.25 to 200 µg/ml) was evaluated by MTT assay against normal human colon fibroblast (CCD-18Co cell line). At low concentration, all developed composites were found to be non-cytotoxic when treated to the human fibroblast cells and did not elicit cytotoxic effects on cell proliferation and the highest values of cell viability (283%) for the HA/MWCNTs-COOH/BSA composites obtained; whereas when the concentration was increased, the reduction in cell viability was observed. The novel composites showed favorable cytocompatibility with improved compressive strength which make it applicable to use in range of trabecular bone.

  4. 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

  5. Biodistribution of co-exposure to multi-walled carbon nanotubes and nanodiamonds in mice

    NASA Astrophysics Data System (ADS)

    Wei, Qi; Zhan, Li; Juanjuan, Bi; Jing, Wang; Jianjun, Wang; Taoli, Sun; Yi'an, Guo; Wangsuo, Wu

    2012-08-01

    In this work, technetium-99 (99mTc) was used as the radiolabeling isotope to study the biodistribution of oxidized multi-walled carbon nanotubes (oMWCNTs) and/or nanodiamonds (NDs) in mice after intravenous administration. The histological impact of non-radiolabeled oMWCNTs or NDs was investigated in comparison to the co-exposure groups. 99mTc-labeled nanomaterials had high stability in vivo and fast clearance from blood . After a single injection of oMWCNTs, the highest distribution was found in the lungs, with lower uptake in the liver/spleen. As for NDs injected alone, high distribution in the liver, spleen, and lungs was observed right after. However, uptake in the lungs was decreased obviously after 24 h, while high accumulation in the liver or spleen continued. After co-injection of oMWCNTs and NDs, oMWCNTs significantly affected the distribution pattern of NDs in vivo. Meanwhile, the increasing dose of oMWCNTs decreased the hepatic and splenic accumulation of NDs and gradually increased lung retention. On the contrary, the NDs had no significant effects on the distribution of oMWCNTs in mice. Histological photographs showed that oMWCNTs were mainly captured by lung macrophages, and NDs were located in the bronchi and alveoli after co-administration. oMWCNTs and NDs had different modes of micro-cells. In conclusion, the behavior and fate of NDs in mice depended strongly on oMWCNTs, but NDs had a small influence on the biodistribution and excretion pattern of oMWCNTs.

  6. Reinforcement of Polylactic acid using pyrene functionalized Multi-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Isakki, Ram Kumar

    The conventional petroleum polymers are being replaced by the biopolymers that are biodegradable, biocompatible, eco-friendly. But to bridge the gap between them in terms of mechanical and thermal stability, reinforcement is used. This paper deals with the review of literature on production of polylactic acid, the reinforcement materials (natural and synthetic) used in the recent past, characterization methods used to determine the mechanical, thermal and morphological properties of the composites and a new method of functionalizing the Multi-Walled Carbon Nanotubes (MWNT) to improve the bonding with Polylactic acid (PLA) using pi-pi stacking. This method would avoid the damage caused by the harsh pretreatment of MWNTs with strong acids for functionalizing them and also provides an alternative method which is safe and effective. When the MWNTs are treated with 1-pyrene butyl amine, the pi-pi stacking occurs along the walls of the MWNTs which functionalizes them and ensures better bonding. The matrix is PLA and the filler material is the functionalized MWNTs. Composites were prepared varying the concentration of the filler material (0, 1, 3, 5 and 7wt %). The tensile strength and modulus was determined using Instron tensile testing machine, the morphological characteristics using Scanning Electron Microscopy (SEM), the thermal stability using the Thermogravimetric Analyzer (TGA) and the chemical bonding between the matrix and filler material was studied using Fourier Transform Infra-red Spectroscopy (FTIR). The composites prepared with 5 wt% exhibited 74.17% increase in the tensile strength and 117.5% increase in the modulus when compared to the neat PLA. The dispersion of the MWNT was studied using SEM.

  7. Mechanism of Methylene Blue adsorption on hybrid laponite-multi-walled carbon nanotube particles.

    PubMed

    Manilo, Maryna; Lebovka, Nikolai; Barany, Sandor

    2016-04-01

    The kinetics of adsorption and parameters of equilibrium adsorption of Methylene Blue (MB) on hybrid laponite-multi-walled carbon nanotube (NT) particles in aqueous suspensions were determined. The laponite platelets were used in order to facilitate disaggregation of NTs in aqueous suspensions and enhance the adsorption capacity of hybrid particles for MB. Experiments were performed at room temperature (298 K), and the laponite/NT ratio (Xl) was varied in the range of 0-0.5. For elucidation of the mechanism of MB adsorption on hybrid particles, the electrical conductivity of the system as well as the electrokinetic potential of laponite-NT hybrid particles were measured. Three different stages in the kinetics of adsorption of MB on the surface of NTs or hybrid laponite-NT particles were discovered to be a fast initial stage I (adsorption time t=0-10 min), a slower intermediate stage II (up to t=120 min) and a long-lasting final stage III (up to t=24hr). The presence of these stages was explained accounting for different types of interactions between MB and adsorbent particles, as well as for the changes in the structure of aggregates of NT particles and the long-range processes of restructuring of laponite platelets on the surface of NTs. The analysis of experimental data on specific surface area versus the value of Xl evidenced in favor of the model with linear contacts between rigid laponite platelets and NTs. It was also concluded that electrostatic interactions control the first stage of adsorption at low MB concentrations.

  8. Promotion of lung adenocarcinoma following inhalation exposure to multi-walled carbon nanotubes

    PubMed Central

    2014-01-01

    Background Engineered carbon nanotubes are currently used in many consumer and industrial products such as paints, sunscreens, cosmetics, toiletries, electronic processes and industrial lubricants. Carbon nanotubes are among the more widely used nanoparticles and come in two major commercial forms, single-walled carbon nanotubes (SWCNT) and the more rigid, multi-walled carbon nanotubes (MWCNT). The low density and small size of these particles makes respiratory exposures likely. Many of the potential health hazards have not been investigated, including their potential for carcinogenicity. We, therefore, utilized a two stage initiation/promotion protocol to determine whether inhaled MWCNT act as a complete carcinogen and/or promote the growth of cells with existing DNA damage. Six week old, male, B6C3F1 mice received a single intraperitoneal (ip) injection of either the initiator methylcholanthrene(MCA, 10 μg/g BW, i.p.), or vehicle (corn oil). One week after i.p. injections, mice were exposed by inhalation to MWCNT (5 mg/m3, 5 hours/day, 5 days/week) or filtered air (controls) for a total of 15 days. At 17 months post-exposure, mice were euthanized and examined for lung tumor formation. Results Twenty-three percent of the filtered air controls, 26.5% of the MWCNT-exposed, and 51.9% of the MCA-exposed mice, had lung bronchiolo-alveolar adenomas and lung adenocarcinomas. The average number of tumors per mouse was 0.25, 0.81 and 0.38 respectively. By contrast, 90.5% of the mice which received MCA followed by MWCNT had bronchiolo-alveolar adenomas and adenocarcinomas with an average of 2.9 tumors per mouse 17months after exposure. Indeed, 62% of the mice exposed to MCA followed by MWCNT had bronchiolo-alveolar adenocarcinomas compared to 13% of the mice that received filtered air, 22% of the MCA-exposed, or 14% of the MWCNT-exposed. Mice with early morbidity resulting in euthanasia had the highest rate of metastatic disease. Three mice exposed to both MCA and

  9. Preparation, loading, and cytotoxicity analysis of polymer nanotubes from an ethylene glycol dimethacrylate homopolymer in comparison to multi-walled carbon nanotubes.

    PubMed

    Newland, Ben; Thomas, Laurent; Zheng, Yu; Steinhart, Martin; Werner, Carsten; Wang, Wenxin

    2016-04-01

    Despite concerns over toxicity, carbon nanotubes have been extensively investigated for potential applications in nanomedicine because of their small size, unique properties, and ability to carry cargo such as small molecules and nucleic acids. Herein, we show that polymer nanotubes can be synthesized quickly and easily from a homopolymer of ethylene glycol dimethacrylate (EGDMA). The nanotubes formed via photo-initiated polymerization of the highly functional prepolymer, inside an anodized aluminium oxide template, have a regular structure and large internal pore and can be loaded with a fluorescent dye within minutes representing a simple alternative to multi-walled carbon nanotubes for biomedical applications.

  10. 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.

  11. Significant decrease in thermal conductivity of multi-walled carbon nanotube induced by inter-wall van der Waals interactions

    NASA Astrophysics Data System (ADS)

    Zhang, Xue; Zhou, Wu-Xing; Chen, Xue-Kun; Liu, Yue-Yang; Chen, Ke-Qiu

    2016-05-01

    The thermal transport properties of multi-walled carbon nanotubes (MWCNTs) were investigated by using non-equilibrium molecular dynamics simulation. The results show that the thermal conductivity of MWCNTs decreases significantly comparing to that of single-walled carbon nanotubes (SWCNTs) due to the inter-wall van der Waals interactions. The more interesting is a fact that the thermal conductance of MWCNTs is significantly greater than the thermal conductance summation of each SWCNTs. This is because the thermal conductance of a carbon nanotube protected by an outer tube is much larger than that of one that is not protected. Moreover, we also studied the thermal flux distribution of MWCNTs, and found that the outer tube plays a dominant role in heat energy transfer.

  12. Silylesterification of oxidized multi-wall carbon nanotubes by catalyzed dehydrogenative cross-coupling between carboxylic and hydrosilane functions

    NASA Astrophysics Data System (ADS)

    Seffer, J.-F.; Detriche, S.; Nagy, J. B.; Delhalle, J.; Mekhalif, Z.

    2014-06-01

    Surface modification of oxidized carbon nanotubes (O-CNTs) with silicon based anchoring groups (R-SiR3) is a relatively uncommon approach of the CNTs functionalization. Hydrosilane derivatives constitute an attractive subclass of compounds for silanization reactions on the CNTs surface. In this work, we report on the ZnCl2 catalytically controlled reaction (hydrosilane dehydrogenative cross-coupling, DHCC) of fluorinated hydrosilane probes with the carboxylic functions present on the surface of oxidized multi-wall carbon nanotubes. Carbon nanotubes functionalized with essentially alcohol groups are also used to compare the selectivity of zinc chloride toward carboxylic groups. To assess the efficiency of functionalization, X-ray Photoelectron Spectroscopy is used to determine the qualitative and quantitative composition of the different samples. Solubility tests on the oxidized and silanized MWNTs are also carried out in the framework of the Hansen Solubility Parameters (HSP) theory to apprehend at another scale the effect of DHCC.

  13. Hydrogen storage of multi-walled carbon nanotubes obtained by decomposition of hydrocarbon over Ni-Li/SiO2.

    PubMed

    Ishihara, Tatsumi; Kamimura, Mitsuhiro; Yasuda, Isamu; Nishiguchi, Hiroyasu; Takita, Yusaku

    2004-01-01

    Hydrogen storage into multi-walled carbon nanotubes obtained by the decomposition of hydrocarbons using Ni-Li/SiO2 was investigated. The optimized reaction conditions for the synthesis of carbon nanotubes were 873K and W/F=40 g-cat.h/mol, and carbon nanotubes obtained by C2H6 decomposition were found to exhibit fairly large H2 storage capacity of 1 wt% at room temperature. The storage capacity increased with decreasing temperature and a capacity of 5 wt% was achieved at 77K, with 66% of adsorbed hydrogen being desorbable. Hydrogen adsorption by pi orbital in C-C bond coordination is proposed, observing both weakened Raman adsorption C-C peaks and the thermal release of CH4 after H2 storage.

  14. Rheological and electrical percolation in melt-processed poly(ether ether ketone)/multi-wall carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Bangarusampath, D. S.; Ruckdäschel, Holger; Altstädt, Volker; Sandler, Jan K. W.; Garray, Didier; Shaffer, Milo S. P.

    2009-11-01

    Multi-wall carbon nanotubes were dispersed homogeneously throughout a poly(ether ether ketone) matrix by melt processing. The influence of nanotube content on both rheological and electrical properties was analysed. The dynamic storage modulus, G', shows a characteristic solid-like behavior above 1 wt% nanotubes. A sharp transition from an electrically insulating to a conductive composite was observed between 1 and 1.5 wt%. By applying a power-law relation, the rheological and electrical percolation thresholds were found to be 0.9 wt%, and 1.3 wt%, respectively. Considering this data, Guth's filler reinforcement theory provides a valuable estimation of the aspect ratio of the nanotubes after processing and indicates substantial length degradation during the dispersion process.

  15. 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 O2-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.

  16. Thermal Conductivity of Diamond Packed Electrospun PAN-Based Carbon Fibers Incorporated with Multi Wall Carbon Nanotubes.

    PubMed

    Dong, Qi; Lu, Chunyuan; Tulugan, Kelimu; Jin, Chunzi; Yoon, Soo Jong; Park, Yeong Min; Kim, Tae Gyu

    2016-02-01

    Multi wall carbon nanotubes (MWCNTs) and diamond are renowned as superlative material due to their relatively high thermal conductivity and hardness while comparing with any bulk materials. In this research, polyacrylonitrile (PAN) solution incorporated with MWCNTs at an alteration of mass fractions (0 wt%, 0.6 wt%, 1 wt%, 2 wt%) were fabricated via electrospinning under optimized parameters. Dried composite nanofibers were stabilized and carbonized, after which water base polytrafluorethylene (PTFE) mixed with nano diamond powder solution was spin coated on them. Scanning electron microscopy, Raman spectroscopy, X-ray scattering and Laserflash thermal conductivity were used to characterize the composite nanofiber sheets. The result shows that the thermal conductivity increased to 4.825 W/m K from 2.061 W/mK. The improvement of thermal conductivities is suggesting the incorporation of MWCNTs.

  17. 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

    2017-02-01

    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.

  18. Application of multi-walled carbon nanotubes modified carbon ionic liquid electrode for electrocatalytic oxidation of dopamine.

    PubMed

    Li, Yonghong; Liu, Xinsheng; Liu, Xiaoying; Mai, Nannan; Li, Yuandong; Wei, Wanzhi; Cai, Qingyun

    2011-11-01

    A simple, sensitive, and reliable method based on a multi-walled carbon nanotubes (MWNTs) modified carbon ionic liquid electrode (CILE) has been successfully developed for determination of dopamine (DA) in the presence of ascorbic acid (AA). The acid-treated MWNTs with carboxylic acid functional groups could promote the electron-transfer reaction of DA and inhibit the voltammetric response of AA. Due to the good performance of the ionic liquid, the electrochemical response of DA on the MWNTs/CILE was better than that of other MWNTs modified electrodes. Under the optimum conditions a linear calibration plot was obtained in the range 5.0×10(-8) to 2.0×10(-4) mol L(-1) and the detection limit was 1.0×10(-8) mol L(-1).

  19. 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.

  20. 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.

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

    PubMed Central

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

    2016-01-01

    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/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. PMID:27385226

  2. Dispersibility of vapor phase oxygen and nitrogen functionalized multi-walled carbon nanotubes in various organic solvents

    PubMed Central

    Khazaee, Maryam; Xia, Wei; Lackner, Gerhard; Mendes, Rafael G.; Rümmeli, Mark; Muhler, Martin; Lupascu, Doru C.

    2016-01-01

    The synthesis and characterization of gas phase oxygen- and nitrogen-functionalized multi-walled carbon nanotubes (OMWCNTs and NMWCNTs) and the dispersibility of these tubes in organic solvents were investigated. Recently, carbon nanotubes have shown supreme capacity to effectively enhance the efficiency of organic solar cells (OSCs). A critical challenge is to individualize tubes from their bundles in order to provide homogenous nano-domains in the active layer of OSCs. OMWCNTs and NMWCNTs were synthesized via HNO3 vapor and NH3 treatments, respectively. Surface functional groups and the structure of the tubes were analyzed by temperature-programmed desorption, Fourier transform infrared spectroscopy, transmission electron microscopy, and Raman spectroscopy which confirmed the formation of functional groups on the tube surface and the enhancement of surface defects. Elemental analysis demonstrated that the oxygen and nitrogen content increased with increasing treatment time of the multi-walled carbon nanotube (MWCNT) in HNO3 vapor. According to ultra-violet visible spectroscopy, modification of the MWCNT increased the extinction coefficients of the tubes owing to enhanced compatibility of the functionalized tubes with organic matrices. PMID:27188622

  3. Hydroxylation of multi-walled carbon nanotubes reduces their cytotoxicity by limiting the activation of mitochondrial mediated apoptotic pathway.

    PubMed

    Liu, Zhenbao; Liu, Yanfei; Peng, Dongming

    2014-04-01

    Hydroxylation of carbon nanotubes (CNTs) can enhance their dispersibility in water, and allows the capability to conjugate with other molecules for the expected applications. However, the cytotoxicity of hydroxylated CNTs has not been thoroughly investigated. Here, we compared the cytotoxicity of hydroxylated multi-walled carbon nanotubes (MWCNTs-OH) on a human cell line with that of pristine multi-walled carbon nanotubes (p-MWCNTs). We showed that while both MWCNTs-OH and p-MWCNTs induced apoptosis in a time- and dose-dependent manner, MWCNTs-OH triggered a significantly milder cytotoxic response than that of p-MWCNTs. We further showed that such attenuated response could be attributed to a reduced disruption of the mitochondrial membrane potential (MMP), leading to the attenuation of both cytochrome c (cyt-c) release and activation of caspases. These findings suggest that MWCNTs-OH, could be more biocompatible for in vivo applications than that of p-MWCNTs by limiting the activation of the mitochondrial mediated apoptotic pathway.

  4. Polystyrene-divinylbenzene stationary phases agglomerated with quaternized multi-walled carbon nanotubes for anion exchange chromatography.

    PubMed

    Huang, Zhongping; Wu, Hongwei; Wang, Fengli; Yan, Wenwu; Guo, Weiqiang; Zhu, Yan

    2013-06-14

    This work explores the potential of multi-walled carbon nanotubes as an agglomerated material for ion chromatography stationary phases for the separation of inorganic anions. Polyelectrolytes with quaternary ammonium groups were introduced onto the carbon nanotube surface, based on condensation polymerization of 1,4-butanediol diglycidyl ether (BDDE) and methylamine (MA). Quaternized multi-walled carbon nanotubes (Q-MWCNTs) were electrostatically adsorbed onto the surface of sulfonated polystyrene-divinylbenzene (PS-DVB) beads to generate the anion exchanger, which were confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). A 100mm×4.0mm i.d. column was packed with Q-MWCNTs agglomerated PS-DVB particles, with a capacity of 56μequiv./column. Separation of inorganic anions, such as F(-), Cl(-), NO2(-), Br(-), NO3(-), SO4(2-) and PO4(3-) were performed. The stationary phase was rigid, chemically stable and showed good ion-exchange characteristics. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Processing and Characterization of Multi-Walled Carbon Nanotubes Containing Alumina-Carbon Refractories Prepared by Nanocomposite Powder Technology

    NASA Astrophysics Data System (ADS)

    Liang, Feng; Li, Nan; Liu, Baikuan; He, Zhongyang

    2016-06-01

    Carbon nanotubes (CNTs) have often been used as additives to improve the properties of refractories containing carbon. However, it is very difficult to evenly distribute CNTs in the matrix. In order to solve this difficulty, an alumina/multi-walled carbon nanotube (MWCNT) (AM) composite powder in which MWCNTs had grown on the surfaces of Al2O3 particles was developed and used in alumina-carbon (Al2O3-C) refractories. The effects of the AM composite powders on the microstructure and properties of the Al2O3-C refractories were studied and compared with the commercial MWCNTs. The nanocomposite powders significantly improved the distribution uniformity of MWCNTs in the Al2O3-C matrix. The densification, fracture properties, thermal shock resistance, and slag corrosion resistance were enhanced due to the well-dispersed MWCNTs. On the contrary, no improvement of the densification, fracture properties, and thermal shock resistance of the refractories was achieved by addition of commercial MWCNTs due to the agglomeration of MWCNTs.

  6. 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

  7. Electrochemical unzipping of multi-walled carbon nanotubes for facile synthesis of high-quality graphene nanoribbons.

    PubMed

    Shinde, Dhanraj B; Debgupta, Joyashish; Kushwaha, Ajay; Aslam, Mohammed; Pillai, Vijayamohanan K

    2011-03-30

    Here we report a remarkable transformation of carbon nanotubes (CNTs) to nanoribbons composed of a few layers of graphene by a two-step electrochemical approach. This consists of the oxidation of CNTs at controlled potential, followed by reduction to form graphene nanoribbons (GNRs) having smooth edges and fewer defects, as evidenced by multiple characterization techniques, including Raman spectroscopy, atomic force microscopy, and transmission electron microscopy. This type of "unzipping" of CNTs (single-walled, multi-walled) in the presence of an interfacial electric field provides unique advantages with respect to the orientation of CNTs, which might make possible the production of GNRs with controlled widths and fewer defects.

  8. 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.

  9. Short thio-multi-walled carbon nanotubes and Au nanoparticles enhanced electrochemical DNA biosensor for DNA hybridization detection

    NASA Astrophysics Data System (ADS)

    Guo, Feng; Zhang, Jimei; Dai, Zhao; Zheng, Guo

    2010-07-01

    A novel and sensitive electrochemical DNA biosensor based on multi-walled carbon nanotubes functionalized with a thio group (MWNTs-SH) and gold nanoparticles (GNPs) for covalent DNA immobilization and enhanced hybridization detection is described. The key step for developing this novel DNA biosensor is to cut the pristine MWNT into short and generate lots of active sites simultaneously. With this approach, the target DNA could be quantified in a linear range from 8.5×10-10 to 1.5×10-5 mol/L, with a detection limit of 1.67×10-11 mol/L by 3σ.

  10. Improved electroless plating method through ultrasonic spray atomization for depositing silver nanoparticles on multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zhao, Qi; Xie, Ming; Liu, Yichun; Yi, Jianhong

    2017-07-01

    A novel method was developed to deposit nanosized silver particles on multi-walled carbon nanotubes (MWCNTs). The electroless plating of silver on MWCNTs accomplished in small solution drops generated by ultrasonic spray atomization, which inhibited excessive growth of silver particles and led to much more uniform nanometer grain-sized coatings. The results showed that pretreatment was essential for silver particles to deposit on the MWCNTs, and the electrolyte concentration and reaction temperature were important parameters which had a great influence on the morphology and structure of the silver coatings. Possible mechanisms of this method are also discussed in the paper.

  11. 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.

  12. Influence of amine-grafted multi-walled carbon nanotubes on physical and rheological properties of PMMA-based nanocomposites

    SciTech Connect

    Kim, Ki-Seok; Park, Soo-Jin

    2011-11-15

    In this work, poly(methyl methacrylate) (PMMA) was grafted onto amine treated multi-walled carbon nanotubes (NH-MWNTs) and the physical and rheological properties of the NH-MWNTs-g-PMMA nanocomposites were investigated. The graft reaction of NH-MWNTs and the PMMA matrix was confirmed from the change of the N{sub 1S} peaks, including those of amine oxygen and amide oxygen, by X-ray photoelectron spectroscopy (XPS). The thermal and mechanical properties of the NH-MWNT-g-PMMA nanocomposites were enhanced by the graft reaction between NH-MWNTs and PMMA matrix. In addition, the viscosity of the nanocomposites was increased with the addition of NH-MWNTs. Storage (G') and loss modulus (G'') were significantly increased by increase in the NH-MWNT content compared to acid-treated MWNTs/PMMA nanocomposites. This increase was attributed to the strong interaction by the grafting reaction between NH-MWNTs and the PMMA matrix. - Graphical abstract: This describes the increase of mechanical properties in NH-MWNTs-g-PMMA hybrid composites with different NH-MWNT contents. Highlights: > Aminized carbon nanotubes are used as reinforcement for poly(methylmethacrylate). > Poly(methylmethacrylate) is grafted on aminized carbon nanotubes by thermal reaction. > Grafting of carbon nanotubes and polymer provide enhanced physical properties. > It was due to the strong interaction between carbon nanotubes and polymer matrix.

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

    NASA Astrophysics Data System (ADS)

    Ghasemi, Ali

    2013-03-01

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

  14. Appearance of radial breathing modes in Raman spectra of multi-walled carbon nanotubes upon laser illumination

    NASA Astrophysics Data System (ADS)

    Rai, Padmnabh; Mohapatra, Dipti R.; Hazra, K. S.; Misra, D. S.; Ghatak, Jay; Satyam, P. V.

    2008-03-01

    The Raman spectra of the multi-walled carbon nanotubes are studied with the laser power of 5-20 mW. We observe the Raman bands at ˜1352, 1581, 1607, and 2700 cm -1 with 5 mW laser power. As the laser power is increased to 10, 15 and 20 mW, the radial breathing modes (RBMs) of the single wall carbon nanotubes (SWNTs) appear in the range 200-610 cm -1. The diameter corresponding to the highest RBM is ˜0.37 nm, the lowest reported so far. The RBMs are attributed to the local synthesis of the SWNTs at the top surface of the samples at higher laser power.

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

    PubMed

    Li, Shibin; Irin, Fahmida; Atore, Francis O; Green, Micah J; Cañas-Carrell, Jaclyn E

    2013-02-15

    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, earthworms were first processed into a powder by freeze drying. Then, samples were measured by utilizing 10 s exposure to 30 W microwave power. This method showed the potential to quantitatively measure MWNTs in earthworms at low concentrations (~0.1 μg in 20 mg of earthworm). Also, a simple MWNT bioaccumulation study in earthworms indicated a low bioaccumulation factor of 0.015±0.004. With an appropriate sample processing method and instrumental parameters (power and exposure time), this technique has the potential to quantify MWNTs in a variety of sample types (plants, earthworms, human blood, etc.).

  16. Mechanisms of Multi-walled Carbon Nanotubes-Induced Oxidative Stress and Genotoxicity in Mouse Fibroblast Cells.

    PubMed

    Alarifi, Saud; Ali, Daoud

    2015-01-01

    The extensive production and wide application of carbon nanotubes have made investigations of its toxic potentials necessary. In the present study, we explored the underlying mechanism through which multi-walled carbon nanotubes (MWCNTs) induce toxicity in mouse fibroblast cells (L929). 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and neutral red uptake viability assays were used to examine mechanisms of cytotoxicity. Dose and time-dependent cytotoxicity was observed in L929 cells. The MWCNTs significantly increased the generation of reactive oxygen species, lipid peroxidation, superoxide dismutase, and decreased glutathione. It was observed that the MWCNTs induced caspase 3 activity. The highest DNA strand breakage was detected by comet assay at 300 µg/mL of MWCNTs. Thus, the data indicate that MWCNTs induced cytotoxicity and apoptosis in L929 cells via oxidative stress.

  17. Cellular response of RAW 264.7 to spray-coated multi-walled carbon nanotube films with various surfactants.

    PubMed

    Chen, Hailan; Shen, Jianmin; Longhua, Guo; Chen, Yuan; Kim, Dong-Hwan

    2011-02-01

    The increasing role of carbon nanotubes (CNTs) in various biological applications has led to a number of studies on the cytotoxicity of solution-phase CNTs, but few studies are available concerning the cytotoxicity of CNT films. Herein, we studied the potential health effect of CNT films fabricated with three commercial surfactants (sodium cholate, sodium dodecyl sulfate, and triton X-100). Multi-walled carbon nanotube-surfactant dispersions were coated onto substrates through air-spray technique. Cellular morphology, MTT assays, as well as the expression of TNF-α and IL-1β of RAW 264.7 cells cultured on the spray-coated CNT films were evaluated for cytotoxicity. It was found that the cytotoxicity of the CNT films was largely dependent on the type of surfactant used and could be significantly reduced by mild washing steps. 2010 Wiley Periodicals, Inc.

  18. 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.

  19. Effects of multi-walled carbon nanotubes on the electrogenerated chemiluminescence and fluorescence of CdTe quantum dots.

    PubMed

    Wusimanjiang, Yiliyasi; Meyer, Alexander; Lu, Liping; Miao, Wujian

    2016-10-01

    Effects of multi-walled carbon nanotubes (CNTs) that were immobilized on glassy carbon electrode (GCE) on the electrogenerated chemiluminescence (ECL) of CdTe quantum dots (QDs) using tri-n-propylamine (TPrA) and 2-(dibutylamino)ethanol (DBAE) as the anodic coreactant are reported. Depending on the solution concentration of coreactant and QDs, the surface-confined CNTs could either quench or enhance the ECL intensity. Lowering the solution concentration of QDs was found to be beneficial for enhancing ECL. A V-shaped profile of ECL intensity ratio (at CNTs over bare GCE) versus coreactant concentration suggested that either low or high concentrations of coreactant were needed for effective ECL generation. The ECL quenching by CNTs was believed to follow the typical dynamic quenching mechanism, which was confirmed by fluorescent data that provided a Stern-Volmer and an estimated quenching constant of 11.7 g/L and 1.2 × 10(9) L/g•s, respectively, for the excited state CdTe* quenching by CNTs in solution. Furthermore, the ECL performance at CNTs was also affected by the type of the coreactant used, where up to 30 times enhancement in ECL was observed from the CdTe/DBAE system under the given experimental conditions. Graphical Abstract Illustration of anodic quantum dots ECL enhancement and quenching by multi-walled carbon nanotubes.

  20. Cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode as electrochemical sensor on microfluidic chip.

    PubMed

    Li, Xinchun; Chen, Zuanguang; Zhong, Yuwen; Yang, Fan; Pan, Jianbin; Liang, Yajing

    2012-01-13

    Nanomaterial-based electrochemical sensor has received significant interest. In this work, cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode was electrochemically prepared and exploited as an amperometric detector for microchip electrophoresis. The prepared sensor displayed rapid and sensitive response towards hydrazine and isoniazid oxidation, which was attributed to synergetic electrocatalytic effect of cobalt hexacyanoferrate and multi-walled carbon nanotubes. The sensitivity enhancement with nearly two orders of magnitude was gained, compared with the bare carbon paste electrode, with the detection limit of 0.91 μM (S/N=3) for hydrazine. Acceptable repeatability of the microanalysis system was verified by consecutive eleven injections of hydrazine without chip and electrode treatments, the RSDs for peak current and migration time were 3.4% and 2.1%, respectively. Meanwhile, well-shaped electrophoretic peaks were observed, mainly due to fast electron transfer of electroactive species on the modified electrode. The developed microchip-electrochemistry setup was successfully applied to the determination of hydrazine and isoniazid in river water and pharmaceutical preparation, respectively. Several merits of the novel electrochemical sensor coupled with microfluidic platform, such as comparative stability, easy fabrication and high sensitivity, hold great potential for hydrazine compounds assay in the lab-on-a-chip system. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. 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.

  2. Oriented graphene nanoribbon yarn and sheet from aligned multi-walled carbon nanotube sheets.

    PubMed

    Carretero-González, Javier; Castillo-Martínez, Elizabeth; Dias-Lima, Marcio; Acik, Muge; Rogers, Duncan M; Sovich, Justin; Haines, Carter S; Lepró, Xavier; Kozlov, Mikhail; Zhakidov, Anvar; Chabal, Yves; Baughman, Ray H

    2012-11-08

    Highly oriented graphene nanoribbons sheets and yarns are produced by chemical unzipping of self-standing multiwalled carbon nanotube (MWNT) sheets. The as-produced yarns - after being chemically and thermally reduced - exhibit a good mechanical, electrical, and electrochemical performance.

  3. 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.

  4. Enhancement in insulation and mechanical properties of PMMA nanocomposite foams infused with multi-walled carbon nanotubes.

    PubMed

    Yeh, Jui-Ming; Chang, Kung-Chin; Peng, Chih-Wei; Lai, Mei-Chun; Hwang, Shyh-Shin; Lin, Hong-Ru; Liou, Shir-Joe

    2011-08-01

    In this study, PMMA/CNTs composite materials with carboxyl-multi walled carbon nanotubes (c-MWNTs) or untreated MWNTs were prepared via in-situ bulk polymerization. The as-prepared PMMA/CNTs composite materials were then characterized by Fourier-Transformation infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The molecular weights of PMMA extracted from PMMA/CNTs composite materials and bulk PMMA were determined by gel permeation chromatography (GPC) with THF used as the eluant. The PMMA/CNTs composite materials were used to produce foams by a batch process in an autoclave using nitrogen as foaming agent. The cellular microstructure, insulation and compressive mechanical properties of PMMA/CNTs composite foams were also investigated in detail. Compared to neat PMMA foam, the presence of CNTs increases in cell density and reduces cell size. The insulation and compressive mechanical properties of PMMA/CNTs composite foams were found to improve substantially those of neat PMMA foam. In particular, 22.6% decrease in thermal conductivity, 19.7% decrease in dielectric constant and 160% increase in compressive modulus were observed with the addition of 0.3 wt% carboxyl-multi walled carbon nanotubes (c-MWNTs).

  5. Non-enzymatic Hydrogen Peroxide Sensors Based on Multi-wall Carbon Nanotube/Pt Nanoparticle Nanohybrids

    PubMed Central

    Miao, Zhiying; Zhang, Di; Chen, Qiang

    2014-01-01

    A novel strategy to fabricate a hydrogen peroxide (H2O2) sensor was developed by using platinum (Pt) electrodes modified with multi-wall carbon nanotube-platinum nanoparticle nanohybrids (MWCNTs/Pt nanohybrids). The process to synthesize MWCNTs/Pt nanohybrids was simple and effective. Pt nanoparticles (Pt NPs) were generated in situ in a potassium chloroplatinate aqueous solution in the presence of multi-wall carbon nanotubes (MWCNTs), and readily attached to the MWCNTs convex surfaces without any additional reducing reagents or irradiation treatment. The MWCNT/Pt nanohybrids were characterized by transmission electron microscope (TEM), and the redox properties of MWCNTs/Pt nanohybrids-modified Pt electrode were studied by electrochemical measurements. The MWCNTs/Pt-modified electrodes exhibited a favorable catalytic ability in the reduction of H2O2. The modified electrodes can be used to detect H2O2 in the range of 0.01–2 mM with a lower detection limit of 0.3 μM at a signal-to-noise ratio of 3. The sensitivity of the electrode to H2O2 was calculated to be 205.80 μA mM−1 cm−2 at working potential of 0 mV. In addition, the electrodes exhibited an excellent reusability and long-term stability as well as negligible interference from ascorbic acid, uric acid, and acetaminophen. PMID:28788600

  6. Multi-walled carbon nanotube-impregnated agarose film microextraction of polycyclic aromatic hydrocarbons in green tea beverage.

    PubMed

    Loh, Saw Hong; Sanagi, Mohd Marsin; Wan Ibrahim, Wan Aini; Hasan, Mohamed Noor

    2013-03-15

    A new microextraction procedure termed multi-walled carbon nanotube-impregnated agarose film microextraction (MWCNT-AFME) has been developed. The method utilized multi-walled carbon nanotubes (MWCNTs) immobilized in agarose film to serve as adsorbent in solid phase microextraction (SPME). The film was prepared by mixing the MWCNTs in agarose solution and drying the mixture in oven. Extraction of selected polycyclic aromatic hydrocarbons was performed by inserting a needle through circular MWCNT-impregnated agarose films (5 mm diameter) and the assembly was dipped into an agitated sample solution prior to micro high performance liquid chromatography-ultraviolet analysis. Back extraction was then performed using ultrasonication of the films in 100 μL of solvent. The film was discarded after single use, thus avoiding any analyte carry-over effect. Due to the mesoporous nature of the agarose film, the MWCNTs were immobilized easily within the film and thus allowing for close contact between adsorbent and analytes. Under the optimized extraction conditions, the technique achieved trace LODs in the range of 0.1 to 50 ng L(-1) for the targeted analytes, namely fluoranthene, phenanthrene and benzo[a]pyrene. The method was successfully applied to the analysis of spiked green tea beverage samples with good relative recoveries in the range of 91.1 to 107.2%. The results supported the feasibility of agarose to serve as adsorbent holder in SPME which then minimizes the consumption of chemicals and disposal cost of organic wastes.

  7. Application of polypyrrole multi-walled carbon nanotube composite layer for detection of mercury, lead and iron ions using surface plasmon resonance technique.

    PubMed

    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°.

  8. 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

  9. Multibiomarker response in the earthworm Eisenia fetida as tool for assessing multi-walled carbon nanotube ecotoxicity.

    PubMed

    Calisi, A; Grimaldi, A; Leomanni, A; Lionetto, M G; Dondero, F; Schettino, T

    2016-05-01

    Carbon nanotubes have received a great attention in the last years thanks to their remarkable structural, electrical, and chemical properties. Nowadays carbon nanotubes are increasingly found in terrestrial and aquatic environment and potential harmful impacts of these nanoparticles on humans and wildlife are attracting increasing research and public attention. The effects of carbon nanotubes on aquatic organisms have been explored by several authors, but comparatively the information available on the impact of these particles on soil organisms is much less. Earthworms have traditionally been considered to be convenient indicators of land use impact and soil fertility. The aim of this work was to study the integrated response of a suite of biomarkers covering molecular to whole organism endpoints for the assessment of multi-walled carbon nanotube (MWCNTs) effects on earthworms (Eisenia fetida) exposed to spiked soil. Results showed that cellular and biochemical responses, such as immune cells morphometric alterations and lysosomal membrane destabilization, acetylcholinesterase inhibition and metallothionein tissue concentration changes, showed high sensitivity to MWCNTs exposure. They can improve our understanding and ability to predict chronic toxicity outcomes of MWCNTs exposure such as reproductive alterations. In this context although more investigation is needed to understand the mechanistic pathway relating the biochemical and cellular biomarker analyzed to reproductive alterations, the obtained results give an early contribution to the future development of an adverse outcomes pathways for MWCNTs exposure.

  10. Palladium and palladium-tin supported on multi wall carbon nanotubes or carbon for alkaline direct ethanol fuel cell

    NASA Astrophysics Data System (ADS)

    Geraldes, Adriana Napoleão; Furtunato da Silva, Dionisio; Martins da Silva, Júlio César; Antonio de Sá, Osvaldo; Spinacé, Estevam Vitório; Neto, Almir Oliveira; Coelho dos Santos, Mauro

    2015-02-01

    Pd and PdSn (Pd:Sn atomic ratios of 90:10), supported on Multi Wall Carbon Nanotubes (MWCNT) or Carbon (C), are prepared by an electron beam irradiation reduction method. The obtained materials are characterized by X-Ray diffraction (XRD), Energy dispersive X-ray analysis (EDX), Transmission electron Microscopy (TEM) and Cyclic Voltammetry (CV). The activity for ethanol electro-oxidation is tested in alkaline medium, at room temperature, using Cyclic Voltammetry and Chronoamperometry (CA) and in a single alkaline direct ethanol fuel cell (ADEFC), in the temperature range of 60-90 °C. CV analysis finds that Pd/MWCNT and PdSn/MWCNT presents onset potentials changing to negative values and high current values, compared to Pd/C and PdSn/C electrocatalysts. ATR-FTIR analysis, performed during the CV, identifies acetate and acetaldehyde as principal products formed during the ethanol electro-oxidation, with low conversion to CO2. In single fuel cell tests, at 85 °C, using 2.0 mol L-1 ethanol in 2.0 mol L-1 KOH solutions, the electrocatalysts supported on MWCNT, also, show higher power densities, compared to the materials supported on carbon: PdSn/MWCNT, presents the best result (36 mW cm-2). The results show that the use of MWCNT, instead of carbon, as support, plus the addition of small amounts of Sn to Pd, improves the electrocatalytic activity for Ethanol Oxidation Reaction (EOR).

  11. Development of Pd and Pd-Co catalysts supported on multi-walled carbon nanotubes for formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Morales-Acosta, D.; Ledesma-Garcia, J.; Godinez, Luis A.; Rodríguez, H. G.; Álvarez-Contreras, L.; Arriaga, L. G.

    Pd-Co and Pd catalysts were prepared by the impregnation synthesis method at low temperature on multi-walled carbon nanotubes (MWCNTs). The nanotubes were synthesized by spray pyrolysis technique. Both catalysts were obtained with high homogeneous distribution and particle size around 4 nm. The morphology, composition and electrocatalytic properties were investigated by transmission electron microscopy, scanning electron microscopy-energy dispersive X-ray analysis, X-ray diffraction and electrochemical measurements, respectively. The electrocatalytic activity of Pd and PdCo/MWCNTs catalysts was investigated in terms of formic acid electrooxidation at low concentration in H 2SO 4 aqueous solution. The results obtained from voltamperometric studies showed that the current density achieved with the PdCo/MWCNTs catalyst is 3 times higher than that reached with the Pd/MWCNTs catalyst. The onset potential for formic acid electrooxidation on PdCo/MWCNTs electrocatalyst showed a negative shift ca. 50 mV compared with Pd/MWCNTs.

  12. Relevance of octanol-water distribution measurements to the potential ecological uptake of multi-walled carbon nanotubes.

    PubMed

    Petersen, Elijah J; Huang, Qingguo; Weber, Walter J

    2010-05-01

    Many potential applications of carbon nanotubes (CNTs) require various physicochemical modifications prior to use, suggesting that nanotubes having varied properties may pose risks in ecosystems. A means for estimating bioaccumulation potentials of variously modified CNTs for incorporation in predictive fate models would be highly valuable. An approach commonly used for sparingly soluble organic contaminants, and previously suggested for use as well with carbonaceous nanomaterials, involves measurement of their octanol-water partitioning coefficient (KOW) values. To test the applicability of this approach, a methodology was developed to measure apparent octanol-water distribution behaviors for purified multi-walled carbon nanotubes and those acid treated. Substantial differences in apparent distribution coefficients between the two types of CNTs were observed, but these differences did not influence accumulation by either earthworms (Eisenia foetida) or oligochaetes (Lumbriculus variegatus), both of which showed minimal nanotube uptake for both types of nanotubes. The results suggest that traditional distribution behavior-based KOW approaches are likely not appropriate for predicting CNT bioaccumulation.

  13. The effect of surface oxides on multi-walled carbon nanotube aqueous colloidal properties

    NASA Astrophysics Data System (ADS)

    Smith, Billy

    Carbonaceous nanomaterials are being produced and integrated into consumer products and specialized applications at an accelerating rate. Recently, however, concerns have increased about the environmental, health and safety risks of these nanomaterials, particularly those chemically functionalized to enhance their aqueous colloidal stability and biocompatibility. In this dissertation research, I have investigated the role that surface-oxide concentration plays in the aqueous colloidal stability of multi-walled carbon nanotubes (MWCNTs), a prominent class of engineered nanomaterials. To vary the concentration of surface oxides on the MWCNTs' surface, pristine (unmodified) tubes were treated with a wet-chemical oxidant (e.g., HNO3, H2SO4 /HNO3, KMnO4); the concentration of surface oxides imparted was measured by x-ray photoelectron spectroscopy (XPS). In conjunction with XPS, previously developed chemical derivatization techniques were used to determine the distribution of hydroxyl, carboxyl, and carbonyl functional groups present on the MWCNTs' surface. The length distribution and structural integrity of pristine and oxidized MWCNTs were characterized using atomic force microscopy and transmission electron microscopy, respectively. To examine the aqueous colloidal stability and aggregation properties of oxidized MWCNTs, sedimentation and time-resolved dynamic light scattering (TR-DLS) experiments were conducted on neat (i.e., ideal) suspensions prepared by prolonged sonication of MWCNTs in Milli-Q water. Over a range of environmentally relevant pH values (4--9) and electrolyte (NaCL, CaCl2) concentrations (0.001--1.000 M), the aggregation and colloidal properties of MWCNTs were found to agree with the basic tenants of DLVO theory, in that ( i) more highly oxidized, negatively charged MWCNTs remained stable over a wider range of solution conditions than lowly oxidized tubes, ( ii) oxidized MWCNTs adhered to the empirical Schulze-Hardy rule, and (iii) in early

  14. Electrochemical behavior and voltammetric determination of norfloxacin at glassy carbon electrode modified with multi walled carbon nanotubes/Nafion.

    PubMed

    Huang, Ke-Jing; Liu, Xue; Xie, Wan-Zhen; Yuan, Hong-Xia

    2008-07-15

    A simple and rapid electrochemical method is developed for the determination of trace-level norfloxacin, based on the excellent properties of multi-walled carbon nanotubes (MWCNTs). The MWCNTs/Nafion film-coated glassy carbon electrode (GCE) is constructed and the electrochemical behavior of norfloxacin at the electrode is investigated in detail. The results indicate that MWCNTs modified glassy carbon electrode exhibited efficiently electrocatalytic oxidation for norfloxacin (NFX) with relatively high sensitivity, stability and life time. Under conditions of cyclic voltammetry, the current for oxidation of selected analyte is enhanced significantly in comparison to the bare GCE. The electrocatalytic behavior is further exploited as a sensitive detection scheme for the analyte determinations by linear sweep voltammetry (LSV). Under optimized condition in voltammetric method the concentration calibration range and detection limit (S/N=3) are 0.1-100 micromol/L and 5 x 10(-8)mol/L for NFX. The proposed method was successfully applied to NFX determination in tablets. The analytical performance of this sensor has been evaluated for detection of the analyte in urine as a real sample.

  15. 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.

  16. Nanomechanical behavior of MoS2 and WS2 multi-walled nanotubes and Carbon nanohorns

    PubMed Central

    Maharaj, Dave; Bhushan, Bharat

    2015-01-01

    Nano-objects have been investigated for drug delivery, oil detection, contaminant removal, and tribology applications. In some applications, they are subjected to friction and deformation during contact with each other and their surfaces on which they slide. Experimental studies directly comparing local and global deformation are lacking. This research performs nanoindentation (local deformation) and compression tests (global deformation) with a nanoindenter (sharp tip and flat punch, respectively) on molybdenum disulfide (MoS2) multi-walled nanotubes (MWNTs), ~500 nm in diameter. Hardness of the MoS2 nanotube was similar to bulk and does not follow the “smaller is stronger” phenomenon as previously reported for other nano-objects. Tungsten disulfide (WS2) MWNTs, ~300 nm in diameter and carbon nanohorns (CNHs) 80–100 nm in diameter were of interest and also selected for compression studies. These studies aid in understanding the mechanisms involved during global deformation when nano-objects are introduced to reduce friction and wear. For compression, highest loads were required for WS2 nanotubes, then MoS2 nanotubes and CNHs to achieve the same displacement. This was due to the greater number of defects with the MoS2 nanotubes and the flexibility of the CNHs. Repeat compression tests of nano-objects were performed showing a hardening effect for all three nano-objects. PMID:25702922

  17. Nanomechanical behavior of MoS2 and WS2 multi-walled nanotubes and Carbon nanohorns

    NASA Astrophysics Data System (ADS)

    Maharaj, Dave; Bhushan, Bharat

    2015-02-01

    Nano-objects have been investigated for drug delivery, oil detection, contaminant removal, and tribology applications. In some applications, they are subjected to friction and deformation during contact with each other and their surfaces on which they slide. Experimental studies directly comparing local and global deformation are lacking. This research performs nanoindentation (local deformation) and compression tests (global deformation) with a nanoindenter (sharp tip and flat punch, respectively) on molybdenum disulfide (MoS2) multi-walled nanotubes (MWNTs), ~500 nm in diameter. Hardness of the MoS2 nanotube was similar to bulk and does not follow the ``smaller is stronger'' phenomenon as previously reported for other nano-objects. Tungsten disulfide (WS2) MWNTs, ~300 nm in diameter and carbon nanohorns (CNHs) 80-100 nm in diameter were of interest and also selected for compression studies. These studies aid in understanding the mechanisms involved during global deformation when nano-objects are introduced to reduce friction and wear. For compression, highest loads were required for WS2 nanotubes, then MoS2 nanotubes and CNHs to achieve the same displacement. This was due to the greater number of defects with the MoS2 nanotubes and the flexibility of the CNHs. Repeat compression tests of nano-objects were performed showing a hardening effect for all three nano-objects.

  18. Nanomechanical behavior of MoS2 and WS2 multi-walled nanotubes and carbon nanohorns.

    PubMed

    Maharaj, Dave; Bhushan, Bharat

    2015-02-23

    Nano-objects have been investigated for drug delivery, oil detection, contaminant removal, and tribology applications. In some applications, they are subjected to friction and deformation during contact with each other and their surfaces on which they slide. Experimental studies directly comparing local and global deformation are lacking. This research performs nanoindentation (local deformation) and compression tests (global deformation) with a nanoindenter (sharp tip and flat punch, respectively) on molybdenum disulfide (MoS2) multi-walled nanotubes (MWNTs), ~500 nm in diameter. Hardness of the MoS2 nanotube was similar to bulk and does not follow the "smaller is stronger" phenomenon as previously reported for other nano-objects. Tungsten disulfide (WS2) MWNTs, ~300 nm in diameter and carbon nanohorns (CNHs) 80-100 nm in diameter were of interest and also selected for compression studies. These studies aid in understanding the mechanisms involved during global deformation when nano-objects are introduced to reduce friction and wear. For compression, highest loads were required for WS2 nanotubes, then MoS2 nanotubes and CNHs to achieve the same displacement. This was due to the greater number of defects with the MoS2 nanotubes and the flexibility of the CNHs. Repeat compression tests of nano-objects were performed showing a hardening effect for all three nano-objects.

  19. Interaction forces and conduction properties between multi wall carbon nanotube tips and Au(111).

    PubMed

    Luna, M; de Pablo, P J; Colchero, J; Gomez-Herrero, J; Baro, A M; Tokumoto, H; Jarvis, S P

    2003-07-01

    We have studied the interaction forces and electrical conduction properties arising between multiwall carbon nanotube tips and the Au(111) surface in air, by means of amplitude modulation scanning force microscopy, also called intermittent contact. We have centered our work on tips with metallic electronic structure and for the specific parameters used we have found a preliminary interaction range where there is no contact between tip and surface. Stable imaging in this non-contact range is possible with multiwall carbon nanotube tips. These tips have also been used to obtain simultaneous topographic and current maps of the surface. They show excellent properties as tips due to their high aspect ratio and durability, as a result of their elastic and non-reactive properties. Correspondingly, multiwall carbon nanotube tips allow high resolution local analysis of electrical conductivity on a nanometer scale.

  20. Development of electrochemical method for the determination of olaquindox using multi-walled carbon nanotubes modified glassy carbon electrode.

    PubMed

    Xu, Tianci; Zhang, Lei; Yang, Jichun; Li, Na; Yang, Lijun; Jiang, Xiaoqing

    2013-05-15

    A simple and highly sensitive method for the electrochemical determination of olaquindox (OLA) was developed, which was carried out on the multi-walled carbon nanotubes (MWCNT) modified glassy carbon electrode (MWCNT/GCE) using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results showed that MWCNT remarkably enhanced the reduction of OLA, which improved the cathodic peak current of OLA significantly. Under the optimum condition, the linear range for the calibration curve was 0.3-18.0 μg mL(-1) with a detection limit of 0.26 μg mL(-1). The MWCNT/GCE showed a well reproducibility and the relative standard deviation (R.S.D.) was 3.5% (n=9). And a great anti-interference ability of the MWCNT/GCE was also observed. Finally, the MWCNT/GCE was satisfactorily employed to analyze some synthetic and real water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Adsorption of Reactive Red M-2BE dye from water solutions by multi-walled carbon nanotubes and activated carbon.

    PubMed

    Machado, Fernando M; Bergmann, Carlos P; Fernandes, Thais H M; Lima, Eder C; Royer, Betina; Calvete, Tatiana; Fagan, Solange B

    2011-09-15

    Multi-walled carbon nanotubes and powdered activated carbon were used as adsorbents for the successful removal of Reactive Red M-2BE textile dye from aqueous solutions. The adsorbents were characterised by infrared spectroscopy, N(2) adsorption/desorption isotherms and scanning electron microscopy. The effects of pH, shaking time and temperature on adsorption capacity were studied. In the acidic pH region (pH 2.0), the adsorption of the dye was favourable using both adsorbents. The contact time to obtain equilibrium at 298K was fixed at 1h for both adsorbents. The activation energy of the adsorption process was evaluated from 298 to 323K for both adsorbents. The Avrami fractional-order kinetic model provided the best fit to the experimental data compared with pseudo-first-order or pseudo-second-order kinetic adsorption models. For Reactive Red M-2BE dye, the equilibrium data were best fitted to the Liu isotherm model. Simulated dyehouse effluents were used to check the applicability of the proposed adsorbents for effluent treatment.

  2. 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.

  3. Anodic stripping voltammetric determination of mercury using multi-walled carbon nanotubes film coated glassy carbon electrode.

    PubMed

    Yi, Hongchao

    2003-10-01

    An electrochemical method for the determination of trace levels of mercury based on a multi-walled carbon nanotubes (MWNT) film coated glassy carbon electrode (GCE) is described. In 0.1 mol L(-1) HCl solution containing 0.02 mol L(-1) KI, Hg(2+) was firstly preconcentrated at the MWNT film and then reduced at -0.60 V. During the anodic potential sweep, reduced mercury was oxidized, and then a sensitive and well-defined stripping peak at about -0.20 V appeared. Under identical conditions, a MWNT film coated GCE greatly enhances the stripping peak current of mercury in contrast to a bare GCE. Low concentrations of I(-) remarkably improve the determining sensitivity, since this increases the accumulation efficiency of Hg(2+) at the MWNT film coated GCE. The stripping peak current is proportional to the concentration of Hg(2+) over the range 8 x 10(-10)-5 x 10(-7) mol L(-1). The lowest detectable concentration of Hg(2+) is 2 x 10(-10) mol L(-1) at 5 min accumulation. The relative standard deviation (RSD) at 1 x 10(-8) mol L(-1) Hg(2+) was about 6% ( n=10). By using this proposed method, Hg(2+) in some water samples was determined, and the results were compared with those obtained by atomic absorption spectrometry (AAS). The two results are similar, suggesting that the MWNT-film coated GCE has great potential in practical analysis.

  4. Single-walled carbon nanotube, multi-walled carbon nanotube and Fe2O3 nanoparticles induced mitochondria mediated apoptosis in melanoma cells.

    PubMed

    Naserzadeh, Parvaneh; Ansari Esfeh, Fatemeh; Kaviani, Mahboubeh; Ashtari, Khadijeh; Kheirbakhsh, Raheleh; Salimi, Ahmad; Pourahmad, Jalal

    2017-08-18

    Nanomaterials (NM) exhibit novel anticancer properties. The toxicity of three nanoparticles that are currently being produced in high tonnage including single-walled carbon nanotube (SWCNT), multi-walled carbon nanotube (MWCNT) and Fe2O3 nanoparticles, were compared with normal and melanoma cells. All tested nanoparticles induced selective toxicity and caspase 3 activation through mitochondria pathway in melanoma cells and mitochondria cause the generating of reactive oxygen species (ROS), mitochondrial membrane potential decline (MMP collapse), mitochondria swelling, and cytochrome c release. The pretreatment of butylated hydroxytoluene (BHT), a cell-permeable antioxidant and cyclosporine A (Cs. A), a mitochondrial permeability transition (MPT), pore sealing agent decreased cytotoxicity, caspase 3 activation, ROS generation, and mitochondrial damages induced by SWCNT, MWCNT, and IONPs. Our promising results provide a potential approach for the future therapeutic use of SWCNT, MWCNT, and IONPs in melanoma through mitochondrial targeting.

  5. 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

  6. Electrocatalytic response of poly(cobalt tetraaminophthalocyanine)/multi-walled carbon nanotubes-Nafion modified electrode toward sulfadiazine in urine.

    PubMed

    Hong, Xiao-ping; Zhu, Yan; Zhang, Yan-zhen

    2012-06-01

    A highly sensitive amperometric sulfadiazine sensor fabricated by electrochemical deposition of poly(cobalt tetraaminophthalocyanine) (poly(Co(II)TAPc)) on the surface of a multi-walled carbon nanotubes-Nafion (MWCNTs-Nafion) modified electrode is described. This electrode showed a very attractive performance by combining the advantages of Co(II)TAPc, MWCNTs, and Nafion. Compared with the bare glassy carbon electrode (GCE) and the MWCNTs-Nafion modified electrode, the electrocatalytic activity of poly(Co(II)TAPc)-coated MWCNTs-Nafion GCE generated greatly improved electrochemical detections toward sulfadiazine including low oxidation potential, high current responses, and good anti-fouling performance. The oxidation peak currents of sulfadiazine obtained on the new modified electrode increased linearly while increasing the concentration of sulfadiazine from 0.5 to 43.5 μmol/L with the detection limit of 0.17 μmol/L.

  7. Multi-Walled Carbon Nanotubes as a Catalyst for Gas-Phase Oxidation of Ethanol to Acetaldehyde.

    PubMed

    Wang, Jia; Huang, Rui; Feng, Zhenbao; Liu, Hongyang; Su, Dangsheng

    2016-07-21

    Multi-walled carbon nanotubes (CNTs) were directly used as a sustainable and green catalyst to convert ethanol into acetaldehyde in the presence of molecular oxygen. The C=O groups generated on the nanocarbon surface were demonstrated as active sites for the selective oxidation of ethanol to acetaldehyde. The transformation of disordered carbon debris on the CNT surface to ordered graphitic structures induced by thermal-treatment significantly enhanced the stability of the active C=O groups, and thus the catalytic performance. A high reactivity with approximately 60 % ethanol conversion and 93 % acetaldehyde selectivity was obtained over the optimized CNT catalyst at 270 °C. More importantly, the catalytic performance was quite stable even after 500 h, which is comparable with a supported gold catalyst. The robust catalytic performance displayed the potential application of CNTs in the industrial catalysis field.

  8. Electrooxidation of ethanol on novel multi-walled carbon nanotube supported platinum-antimony tin oxide nanoparticle catalysts

    NASA Astrophysics Data System (ADS)

    Guo, Dao-Jun

    We synthesize the new Pt based catalyst for direct ethanol fuel cells using novel multi-walled carbon nanotubes supported platinum-antimony tin oxide (Pt-ATO/MWCNT) nanoparticle as new catalyst support for the first time. The structure of Pt-ATO/MWCNT catalyst is characterized by transmission electron micrograph (TEM) and X-ray diffraction (XRD). The electrocatalytic properties of Pt-ATO/MWCNT catalyst for ethanol electrooxidation reactions are investigated by cyclic voltammetry (CV) and chronoamperometric experiments in acidic medium. The electrocatalytic activity for ethanol electrooxidation reaction shows that high carbon monoxide tolerance and good stability of Pt-ATO/MWCNT catalyst compared with Pt-SnO 2/MWCNT and commercial Pt/C are observed. These results imply that Pt-ATO/MWCNT catalyst has promising potential applications in direct alcohol fuel cells.

  9. Comparison of 4-chloro-2-nitrophenol adsorption on single-walled and multi-walled carbon nanotubes

    PubMed Central

    2012-01-01

    The adsorption characteristics of 4-chloro-2-nitrophenol (4C2NP) onto single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) from aqueous solution were investigated with respect to the changes in the contact time, pH of solution, carbon nanotubes dosage and initial 4C2NP concentration. Experimental results showed that the adsorption efficiency of 4C2NP by carbon nanotubes (both of SWCNTs and MWCNTs) increased with increasing the initial 4C2NP concentration. The maximum adsorption took place in the pH range of 2–6. The linear correlation coefficients of different isotherm models were obtained. Results revealed that the Langmuir isotherm fitted the experimental data better than the others and based on the Langmuir model equation, maximum adsorption capacity of 4C2NP onto SWCNTs and MWCNTs were 1.44 and 4.42 mg/g, respectively. The observed changes in the standard Gibbs free energy, standard enthalpy and standard entropy showed that the adsorption of 4C2NP onto SWCNTs and MWCNTs is spontaneous and exothermic in the temperature range of 298–328 K. PMID:23369489

  10. Responses of soil ammonia-oxidizing microorganisms to repeated exposure of single-walled and multi-walled carbon nanotubes.

    PubMed

    Chen, Qinglin; Wang, Hui; Yang, Baoshan; He, Fei; Han, Xuemei; Song, Ziheng

    2015-02-01

    The impacts of carbon nanotubes (CNTs) including single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs) on soil microbial biomass and microbial community composition (especially on ammonium oxidizing microorganisms) have been evaluated. The first exposure of CNTs lowered the microbial biomass immediately, but the values recovered to the level of the control at the end of the experiment despite the repeated addition of CNTs. The abundance and diversity of ammonium-oxidizing archaea (AOA) were higher than that of ammonium-oxidizing bacteria (AOB) under the exposure of CNTs. The addition of CNTs decreased Shannon-Wiener diversity index of AOB and AOA. Two-way ANOVA analysis showed that CNTs had significant effects on the abundance and diversity of AOB and AOA. Dominant terminal restriction fragments (TRFs) of AOB exhibited a positive relationship with NH4(+), while AOA was on the contrary. It implied that AOB prefer for high-NH4(+) soils whereas AOA is favored in low NH4(+) soils in the CNT-contaminated soil. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Synthesis and characterization of polyamidoamine dendrimer-coated multi-walled carbon nanotubes and their application in gene delivery systems

    NASA Astrophysics Data System (ADS)

    Pan, Bifeng; Cui, Daxiang; Xu, Ping; Ozkan, Cengiz; Feng, Gao; Ozkan, Mihri; Huang, Tuo; Chu, Bingfeng; Li, Qing; He, Rong; Hu, Guohan

    2009-03-01

    With the aim of improving the amount and delivery efficiency of genes taken by carbon nanotubes into human cancer cells, different generations of polyamidoamine dendrimer modified multi-walled carbon nanotubes (dMNTs) were fabricated, and characterized by high-resolution transmission electron microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis, revealing the presence of dendrimer capped on the surface of carbon nanotubes. The dMNTs fully conjugated with FITC-labeled antisense c-myc oligonucleotides (asODN), those resultant asODN-dMNTs composites were incubated with human breast cancer cell line MCF-7 cells and MDA-MB-435 cells, and liver cancer cell line HepG2 cells, and confirmed to enter into tumor cells within 15 min by laser confocal microscopy. These composites inhibited the cell growth in time- and dose-dependent means, and down-regulated the expression of the c-myc gene and C-Myc protein. Compared with the composites of CNT-NH2-asODN and dendrimer-asODN, no. 5 generation of dendrimer-modified MNT-asODN composites exhibit maximal transfection efficiencies and inhibition effects on tumor cells. The intracellular gene transport and uptake via dMNTs should be generic for the mammalian cell lines. The dMNTs have potentials in applications such as gene or drug delivery for cancer therapy and molecular imaging.

  12. Flame Synthesis of Single- and Multi-Walled Carbon Nanotubes and Nanofibers

    NASA Technical Reports Server (NTRS)

    VanderWal, R. L.; Ticich, Thomas M.

    2001-01-01

    Metal-catalyzed carbon nanotubes are highly sought for a diverse range of applications that include nanoelectronics, battery electrode material, catalysis, hydrogen storage media and reinforcing agents in polymer composites. These latter applications will require vast quantities of nanotubes at competitive prices to be economically feasible. Moreover, reinforcing applications may not require ultrahigh purity nanotubes. Indeed, functionalization of nanotubes to facilitate interfacial bonding within composites will naturally introduce defects into the tube walls, lessening their tensile strength. Current methods of aerosol synthesis of carbon nanotubes include laser ablation of composite targets of carbon and catalyst metal within high temperature furnaces and decomposition of a organometallics in hydrocarbons mixtures within a tube furnace. Common to each approach is the generation of particles in the presence of the reactive hydrocarbon species at elevated temperatures. In the laser-ablation approach, the situation is even more dynamic in that particles and nanotubes are borne during the transient cooling phase of the laser-induced plasma for which the temperature far exceeds that of the surrounding hot gases within the furnace process tube. A shared limitation is that more efficient methods of nanoparticle synthesis are not readily incorporated into these approaches. In contrast, combustion can quite naturally create nanomaterials such as carbon black. Flame synthesis is well known for its commercial scalability and energy efficiency. However, flames do present a complex chemical environment with steep gradients in temperature and species concentrations. Moreover, reaction times are limited within buoyant driven flows to tens of milliseconds. Therein microgravity can greatly lessen temperature and spatial gradients while allowing independent control of flame residence times. In preparation for defining the microgravity experiments, the work presented here focuses

  13. Subcutaneous injection of water-soluble multi-walled carbon nanotubes in tumor-bearing mice boosts the host immune activity

    NASA Astrophysics Data System (ADS)

    Meng, Jie; Yang, Man; Jia, Fumin; Kong, Hua; Zhang, Weiqi; Wang, Chaoying; Xing, Jianmin; Xie, Sishen; Xu, Haiyan

    2010-04-01

    The immunological responses induced by oxidized water-soluble multi-walled carbon nanotubes on a hepatocarcinoma tumor-bearing mice model via a local administration of subcutaneous injection were investigated. Experimental results show that the subcutaneously injected carbon nanotubes induced significant activation of the complement system, promoted inflammatory cytokines' production and stimulated macrophages' phagocytosis and activation. All of these responses increased the general activity of the host immune system and inhibited the progression of tumor growth.

  14. 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.

  15. 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.

  16. Noncovalently functionalized multi-wall carbon nanotubes in aqueous solution using the hydrophobin HFBI and their electroanalytical application.

    PubMed

    Wang, Xinsheng; Wang, Huicai; Huang, Yujian; Zhao, Zixia; Qin, Xia; Wang, Yanyan; Miao, Zhiying; Chen, Qiang; Qiao, Mingqiang

    2010-11-15

    A novel noncovalent approach was developed for the functionalization of multi-wall carbon nanotubes (MWNTs) using the hydrophobin, HFBI. Owing to the amphipathic nature, HFBI can be adopted onto the surface of MWNTs to form HFBI-MWNTs nanocomposite with good dispersion in water. The HFBI-MWNTs nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and water contact angle measurements (WCA). Furthermore, a glucose biosensor was developed based on HFBI-MWNTs by a one-step casting method. The resulting biosensor displayed high sensitivity, wider linear range, low detection limit, and fast response for glucose detection, which implicated that the HFBI-MWNTs nanocomposite film holds great promise in the design of electrochemical devices, such as sensors and biosensors. Copyright © 2010 Elsevier B.V. All rights reserved.

  17. Improvement on wear resistance property of polyurethane film by compositing plasma-treated multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ogawa, Daisuke; Nakamura, Keiji

    2016-01-01

    We investigated the effect of plasma-treated multi-walled carbon nanotubes (CNTs) that are composited into a polyurethane (PU) film. In this journal article, we especially focused on one of mechanical properties of PU film, the wear resistance, to find how the plasma-treated CNTs give contributions to improve the resistance. Our experimental results showed that plasma-treated CNTs enhanced the wear resistance, in particular, when the CNTs treated with the plasma that was made of nitrogen-oxygen mixture gas. Then, we made measurements with infrared absorption spectroscopy to find the possible causes of the improvement. The measurement showed that the surface of the CNTs treated with nitrogen-oxygen plasma had an indication of isocyanate group, which generally hardens PU film. The plasma likely attached the functional group on CNTs, and then the CNTs added extra wear resistance of a polyurethane film.

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

    PubMed

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

    2012-05-06

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

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

  20. 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.

  1. The surface chemical properties of multi-walled carbon nanotubes modified by thermal fluorination for electric double-layer capacitor

    NASA Astrophysics Data System (ADS)

    Jung, Min-Jung; Jeong, Euigyung; Lee, Young-Seak

    2015-08-01

    The surfaces of multi-walled carbon nanotubes (MWCNTs) were thermally fluorinated at various temperatures to enhance the electrochemical properties of the MWCNTs for use as electric double-layer capacitor (EDLC) electrodes. The fluorine functional groups were added to the surfaces of the MWCNTs via thermal fluorination. The thermal fluorination exposed the Fe catalyst on MWCNTs, and the specific surface area increased due to etching during the fluorination. The specific capacitances of the thermally fluorinated at 100 °C, MWCNT based electrode increased from 57 to 94 F/g at current densities of 0.2 A/g, respectively. This enhancement in capacitance can be attributed to increased polarization of the thermally fluorinated MWCNT surface, which increased the affinity between the electrode surface and the electrolyte ions.

  2. Copper oxide decorated multi-walled carbon nanotubes/ferroelectric liquid crystal composites for faster display devices

    NASA Astrophysics Data System (ADS)

    Malik, Anu; Prakash, Jai; Kumar, Anil; Dhar, Ajay; Biradar, Ashok M.

    2012-09-01

    We present faster display devices based on copper oxide decorated multi-walled carbon nanotubes (MWCNTs) doped ferroelectric liquid crystal (FLC) material. The fastening of the response has been attributed to decrease in rotational viscosity of the FLC material. The ionic impurities were also reduced by doping copper oxide decorated MWCNTs into the FLC material, and the reduction has been attributed to trapping of ions by the guest copper oxide decorated MWCNTs. The observations of fastening the response and reduction of ionic impurities have been verified by experimental data using dielectric and electro-optical studies. The underlying mechanism would certainly help to understand the basic mechanism of interaction of CNTs with FLC molecules and could be applied to fabricate ionic defects free faster display devices.

  3. 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.

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

    PubMed

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

    2014-09-07

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

  5. Overoxidized polypyrrole/multi-walled carbon nanotubes composite modified electrode for in vivo liquid chromatography-electrochemical detection of dopamine.

    PubMed

    Wen, Jingxia; Zhou, Li; Jin, Litong; Cao, Xuni; Ye, Bang-Ce

    2009-07-01

    Overoxidized polypyrrole/multi-walled carbon nanotubes (OPPy/MWNTs) modified electrode has been developed for sensitively detecting dopamine (DA). OPPy films developed outside MWNTs might have a porous morphology. Thus, OPPy/MWNTs films developed by this method do not reject ascorbic acid (AA). However, OPPy/MWNTs modified electrode shows largely enhancing oxidative current responses of DA. When combined with liquid chromatography, it not only obtains a low detection limit of 7.5 x 10(-10) mol L(-1) for DA, but also improves the selectivity of DA detection. Mechanisms for the enhancement are also well discussed in this paper. With this approach, microdialysis has been employed for successful assessment of DA in rat striatum.

  6. Covalent marriage of multi-walled carbon nanotubes (MWNTs) and β-cyclodextrin (β-CD) by silicon coupling reagents

    NASA Astrophysics Data System (ADS)

    Shao, Lu; Mu, Chenzhong; Du, Hongpeng; Czech, Zbigniew; Du, Huachuan; Bai, Yongping

    2011-12-01

    In this study, β-cyclodextrin (β-CD) polymer was covalently bonded to multi-walled carbon nanotubes (MWNTs) with the aid of γ-glycidoxypropyltrimethoxysilane (GPTMS) for the fabrication of novel porous materials with special surface properties. The success of synthesis and physicochemical properties of β-CD polymer grafted MWNTs (MWNTs-g-CDP) were characterized by FT-IR, XPS, TGA, TEM and BET. The novel materials were further utilized to remove the typical contaminant of resorcinol in industrial wastewater. The results illustrated that MWNTs-g-CDP possessed much higher adsorption capability and demonstrated the shorter saturation adsorption time than that of pristine MWNTs. Therefore, MWNTs-g-CDP with the unique pore and surface characteristics may have great potentials in environmental applications.

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

    PubMed

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

    2016-04-28

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

  8. Efficient degradation of methylene blue dye over tungsten trioxide/multi-walled carbon nanotube system as a novel photocatalyst

    NASA Astrophysics Data System (ADS)

    Dinari, Mohammad; Momeni, Mohamad Mohsen; Ahangarpour, Marzieh

    2016-10-01

    Combination of acid-functionalized multi-walled carbon nanotube/tungsten trioxide (MWCNT/WO3) with different MWCNT's weight percentages as visible light-induced photocatalysts for photodegradation of methylene blue (MB) dye was synthesized. These photocatalysts were characterized by Fourier transform infrared, X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, field emission scanning electron microscopy and transmission electron microscopy techniques. Their photocatalytic activities were tested by using MB as a model compound. The results show that the MWCNT/WO3 hybrid nanostructures exhibit higher photocatalytic activity than pure WO3 or MWCNTs due to their higher absorption enhancement in visible light region and effective separation of electrons and holes. The stability of the hybrid was characterized through cyclic photocatalytic test.

  9. Electrocatalytic Detection of Amitrole on the Multi-Walled Carbon Nanotube – Iron (II) tetra-aminophthalocyanine Platform

    PubMed Central

    Siswana, Msimelelo; Ozoemena, Kenneth I.; Nyokong, Tebello

    2008-01-01

    It is shown that iron(II) tetra-aminophthalocyanine complex electropolymerized onto a multi-walled carbon nanotube-modified basal plane pyrolytic graphite electrode greatly enhanced the electrocatalytic detetion of amitrole (a toxic herbicide), resulting in a very low detection limit (0.5 nM) and excellent sensitivity of 8.80±0.44 μA/nM, compared to any known work reported so far. The electrocatalytic detection of amitrole at this electrode occurred at less positive potential (∼0.3 V vs Ag|ACl) and also revealed a typical coupled chemical reaction. The mechanism for this response is proposed. The electrode gave satisfactory selectivity to amitrole in the presence of other potential interfering pesticides in aqueous solutions. PMID:27873803

  10. Electrocatalytic Detection of Amitrole on the Multi-Walled Carbon Nanotube - Iron (II) tetra-aminophthalocyanine Platform.

    PubMed

    Siswana, Msimelelo; Ozoemena, Kenneth I; Nyokong, Tebello

    2008-08-27

    It is shown that iron(II) tetra-aminophthalocyanine complex electropolymerized onto a multi-walled carbon nanotube-modified basal plane pyrolytic graphite electrode greatly enhanced the electrocatalytic detetion of amitrole (a toxic herbicide), resulting in a very low detection limit (0.5 nM) and excellent sensitivity of 8.80±0.44 μA/nM, compared to any known work reported so far. The electrocatalytic detection of amitrole at this electrode occurred at less positive potential (~0.3 V vs Ag|ACl) and also revealed a typical coupled chemical reaction. The mechanism for this response is proposed. The electrode gave satisfactory selectivity to amitrole in the presence of other potential interfering pesticides in aqueous solutions.

  11. Potential Impact of Multi-Walled Carbon Nanotubes Exposure to the Seedling Stage of Selected Plant Species

    PubMed Central

    Begum, Parvin; Ikhtiari, Refi; Fugetsu, Bunshi

    2014-01-01

    Phytotoxicity is a significant consideration in understanding the potential environmental impact of nanoparticles. 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.

  12. Nanowires of Fe/multi-walled carbon nanotubes and nanometric thin films of Fe/MgO

    SciTech Connect

    Newman, Alexander; Khatiwada, Suman; Neupane, Suman; Seifu, Dereje

    2015-04-14

    We observed that nanowires of Fe grown in the lumens of multi-walled carbon nanotubes required four times higher magnetic field strength to reach saturation compared to planar nanometric thin films of Fe on MgO(100). Nanowires of Fe and nanometric thin films of Fe both exhibited two fold magnetic symmetries. Structural and magnetic properties of 1-dimensional nanowires and 2-dimensional nanometric films were studied by several magnetometery techniques. The θ-2θ x-ray diffraction measurements showed that a (200) peak of Fe appeared on thin film samples deposited at higher substrate temperatures. In these samples prepared at higher temperatures, lower coercive field and highly pronounced two-fold magnetic symmetry were observed. Our results show that maximum magnetocrystalline anisotropy occurred for sample deposited at 100 °C and it decreased at higher deposition temperatures.

  13. Polypyrrole/multi-walled carbon nanotube composite for the solid phase extraction of lead(II) in water samples.

    PubMed

    Sahmetlioglu, Ertugrul; Yilmaz, Erkan; Aktas, Ece; Soylak, Mustafa

    2014-02-01

    A multi-walled carbon nanotubes-polypyrrole conducting polymer nanocomposite has been synthesized, characterized and used for the separation and preconcentration of lead at trace levels in water samples prior to its flame atomic absorption spectrometric detection. The analytical parameters like pH, sample volume, eluent, sample flow rate that were affected the retentions of lead(II) on the new nanocomposite were optimized. Matrix effects were also investigated. Limit of detection and preconcentration factors were 1.1 µg L(-1) and 200, respectively. The adsorption capacity of the nanocomposite was 25.0mg lead(II) per gram composite. The validation of the method was checked by using SPS-WW2 Waste water Level 2 certified reference material. The method was applied to the determination of lead in water samples with satisfactory results.

  14. Bio-based hyperbranched thermosetting polyurethane/triethanolamine functionalized multi-walled carbon nanotube nanocomposites as shape memory materials.

    PubMed

    Kalita, Hemjyoti; Karak, Niranjan

    2014-07-01

    Here, bio-based shape memory polymers have generated immense interest in recent times. Here, Bio-based hyperbranched polyurethane/triethanolamine functionalized multi-walled carbon nanotube (TEA-f-MWCNT) nanocomposites were prepared by in-situ pre-polymerization technique. The Fourier transform infrared spectroscopy and the transmission electron microscopic studies showed the strong interfacial adhesion and the homogeneous distribution of TEA-f-MWCNT in the polyurethane matrix. The prepared epoxy cured thermosetting nanocomposites exhibited enhanced tensile strength (6.5-34.5 MPa), scratch hardness (3.0-7.5 kg) and thermal stability (241-288 degrees C). The nanocomposites showed excellent shape fixity and shape recovery. The shape recovery time decreases (24-10 s) with the increase of TEA-f-MWCNT content in the nanocomposites. Thus the studied nanocomposites have potential to be used as advanced shape memory materials.

  15. Enhanced biocompatibility of multi-walled carbon nanotubes by surface modification: Future perspectives for drug delivery system

    NASA Astrophysics Data System (ADS)

    Anandhi, C. M. S.; Asath, R. Mohamed; Mathavan, T.; Benial, A. Milton Franklin

    2017-05-01

    Surface modification of multi-walled carbon nanotubes (MWCNTs) was carried out by introducing mixture of concentrated sulphuric acid and nitric acid by ultrasonication process. The pristine and surface modified MWCNTs were characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), Raman spectroscopy and Scanning electron microscopy (SEM) techniques. FT-IR spectra revealed that the presence of carboxylic acid functional groups on the surface of MWCNTs. The integrated intensity ratio of pristine and surface modified MWCNTs was calculated by Raman spectroscopic analysis. XRD patterns examines the crystallinity of the surface modified MWCNTs. SEM analysis investigates the change in morphology of the surface modified MWCNTs compared with that of pristine, which is due to the attachment of the carboxylic acid functional groups. Surface modified MWCNTs acts as precursors for further functionalization with various biomolecules, which improves the biocompatibility and initiates the implementation of MWCNTs in the field of nanomedicine and targeted drug delivery.

  16. Theoretical study on the electrochemical behavior of norepinephrine at Nafion multi-walled carbon nanotubes modified pyrolytic graphite electrode

    NASA Astrophysics Data System (ADS)

    Song, Yuanzhi

    2007-08-01

    DFT-B3LYP/6-31G (d, p) and HF/6-31G (d, p) calculations are performed for deoxidized norepinephrineat (NP (R)) and its oxidized form (NP (O)). The electrochemistry of norepinephrineat (NP) was studied by cyclic voltammetry (CV) at a pyrolytic graphite electrode modified by Nafion multi-walled carbon nanotubes (MWNTs) in phosphate buffers at pH 6.0, showing that the standard electrode potential of half reaction for NP (O), H +/NP (R) is 0.75l V. This experimental standard electrode potential of half reaction is consistent with that calculated using the energies of solvation and sum of electronic and thermal free energies of NP (R) and NP (O). The frontier orbital theory and Mülliken charges of moleculer explain the electrochemical behavior of CV at modified electrode well. The singlet vertical excited states for NP (R) and NP (O) are also discussed.

  17. Toxicological assessment of multi-walled carbon nanotubes in vitro: potential mitochondria effects on male reproductive cells

    PubMed Central

    Xu, Cheng; Liu, Qian; Liu, Hui; Zhang, Chunlan; Shao, Wentao; Gu, Aihua

    2016-01-01

    Multi-walled carbon nanotubes (MWCNTs) have been widely used in many fields and were reported to cause reversible testis damage in mice at high-dose. However the reproductive effects of low dose MWCNTs remained elusive. Herein, we used the mice spermatocyte cell line (GC-2spd) to assess the reproductive effects of MWCNTs. Size distribution, zeta potential, and intensity of MWCNTs were characterized. A maximal concentration of 0.5 μg/mL MWCNTs was found to be nonlethal to GC-2spd. At this dose, cell cycles and the ROS levels were in normal status. We also found MWCNTs accumulated in mitochondria, which caused potential mitochondrial DNA damage in spermatocyte. Furthermore, the expression level of mitochondria-related genes, the oxygen consumption rate, and cellular ATP content were declined compared to controls, even at the nonlethal dose. Our results suggested for the first time that, in germ cells, mitochondrion was a cellular organelle that accumulated MWCNTs. PMID:27248475

  18. Decorating multi-walled carbon nanotubes with quantum dots for construction of multi-color fluorescent nanoprobes

    NASA Astrophysics Data System (ADS)

    Jia, Nengqin; Lian, Qiong; Tian, Zhong; Duan, Xin; Yin, Min; Jing, Lihong; Chen, Shouhui; Shen, Hebai; Gao, Mingyuan

    2010-01-01

    Novel multi-color fluorescent nanoprobes were prepared by electrostatically assembling differently sized CdTe quantum dots on polyethylenimine (PEI) functionalized multi-walled carbon nanotubes (MWNTs). The structural and optical properties of the nano-assemblies (MWNTs-PEI-CdTe) were characterized by transmission electron microscopy (TEM), electron diffraction spectra (EDS), Raman spectroscopy, confocal microscopy and photoluminescence spectroscopy (PL), respectively. Electrochemical impedance spectroscopy (EIS) was also applied to investigate the electrostatic assembling among oxidized MWNTs, PEI and CdTe. Furthermore, confocal fluorescence microscopy was used to monitor the nano-assemblies' delivery into tumor cells. It was found that the nano-assemblies exhibit efficient intracellular transporting and strong intracellular tracking. These properties would make this luminescent nano-assembly an excellent building block for the construction of intracellular nanoprobes, which could hold great promise for biomedical applications.

  19. Magnetic removal of dyes from aqueous solution using multi-walled carbon nanotubes filled with Fe2O3 particles.

    PubMed

    Qu, Song; Huang, Fei; Yu, Shaoning; Chen, Gang; Kong, Jilie

    2008-12-30

    The Fe2O3 nanoparticles have been introduced into the multi-walled carbon nanotubes (MWCNTs) via wet chemical method. The resulting products are characterized by TEM, EDX, XRD and VSM. The magnetic MWCNTs have been employed as adsorbent for the magnetic separation of dye contaminants from water. The adsorption test of dyes (Methylene Blue and Neutral Red) demonstrates that it only takes 60min to attain equilibrium and the adsorption capacities for Methylene Blue and Neutral Red in the concentration range studied are 42.3 and 77.5mg/g, respectively. The magnetic MWCNTs can be easily manipulated in magnetic field for desired separation, leading to the removal of dyes from polluted water. The integration of MWCNTs with Fe2O3 nanoparticles has great potential application to remove organic dyes from polluted water.

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

    PubMed Central

    2012-01-01

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

  1. Multi-walled carbon nanotube-supported metal-doped ZnO nanoparticles and their photocatalytic property.

    PubMed

    Chen, C S; Liu, T G; Lin, L W; Xie, X D; Chen, X H; Liu, Q C; Liang, B; Yu, W W; Qiu, C Y

    2013-01-01

    A simple and versatile approach has been developed to synthesize multi-walled carbon nanotubes/metal-doped ZnO nanohybrid materials (MWNT/M-doped ZnO) by means of the co-deposition method. The experimental results illuminate that MWNTs can be modified by metal-doped ZnO nanoparticles at 450 °C, such as Mn, Mg, and Co elements. Furthermore, the MWNT/Mg-doped ZnO hybrids have been proven to have a high photocatalytic ability for methyl orange (MO), in which the degraded rate for MO reaches 100 % in 60 min. The enhancement in photocatalytic activity is attributed to the excellent electriconal property of MWNTs and Mg-doping. The resultant MWNT/Mg-doped ZnO nanohybrids have potential applications in photocatalysis and environmental protection.

  2. Preparation and characterization of silver nanoparticles immobilized on multi-walled carbon nanotubes by poly(dopamine) functionalization

    NASA Astrophysics Data System (ADS)

    Jiang, Yi; Lu, Yonglai; Zhang, Liqun; Liu, Li; Dai, Yajie; Wang, Wencai

    2012-06-01

    Multi-walled carbon nanotubes (MWNTs) functionalized with poly(dopamine) (PDA) were found to cause the immobilization of silver nanoparticles on the surface. The PDA functional layer not only improved the dispersion of MWNTs in aqueous solution, but also was used as a platform for subsequent silver nanoparticle immobilization. The surface morphology of the functionalized MWNTs was observed by high-resolution transmission electron microscopy. The results showed that PDA layers with controlled thickness on the nanometer scale were formed on MWNT surfaces by in situ spontaneous oxidative polymerization of dopamine, and that high-density of homogeneously dispersed spherical silver nanoparticles with sizes of 3-4 nm were immobilized on their outer surface. The space between spherical silver nanoparticles is less than 10 nm. Both X-ray photoelectron spectroscopy and X-ray diffraction results showed that the Ag nanoparticles on the surface of hybrids exist in the zero valent state.

  3. Multi-walled carbon nanotubes supported Cu-doped ZnO nanoparticles and their optical property

    NASA Astrophysics Data System (ADS)

    Chen, C. S.; Xie, X. D.; Liu, T. G.; Lin, L. W.; Kuang, J. C.; Xie, X. L.; Lu, L. J.; Cao, S. Y.

    2012-03-01

    Multi-walled carbon nanotubes (MWNTs)/Cu-doped ZnO composite powders were prepared by co-precipitation method, and were characterized by X-ray diffraction, electron microscopy, fluorescence spectrum, and ultraviolet spectrum. Experimental results show that the MWNTs can be modified by Cu-doped ZnO nanoparticles with hexagonal wurtzite structure after annealed at 450 °C, and the nanoparticle size is about 15 nm. Two ultraviolet (UV) peaks and a green band centered at about 510 nm are observed in the fluorescence spectrum of MWNTs/Cu-doped ZnO composite powder annealed at 450 °C. Furthermore, MWNTs and Cu doping significantly improve the UV absorption ability of ZnO.

  4. Fabrication and characterization of polylactic acid and polylactic acid/multi-walled carbon nanotube nanofibers through centrifugal spinning

    NASA Astrophysics Data System (ADS)

    Patlan, Richard

    Biocompatible polymer nanofibers hold great potential in the biomedical engineering field. Their biodegradable nature and enhanced properties could help solve a wide array of health related problems, particularly in the areas of tissue regeneration, drug delivery, and biosensor design. The novel Forcespinning™ method allows the production of submicron fibers without many of the drawbacks found in electrospinning, while also providing a substantial increase in fiber production. The aim of the study was to utilize this method to fabricate non-woven nanofibrous mats composed of polylactic acid (PLA) and polylactic acid/multi-walled carbon nanotube composite fibers. The morphology, thermal properties, and crystalline structure of the resulting nanofibers were then characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and X-Ray Diffraction (XRD).

  5. Effect of Continuous Multi-Walled Carbon Nanotubes on Thermal and Mechanical Properties of Flexible Composite Film

    PubMed Central

    Cha, Ji Eun; Kim, Seong Yun; Lee, Seung Hee

    2016-01-01

    To investigate the effect of continuous multi-walled carbon nanotubes (MWCNTs) on the thermal and mechanical properties of composites, we propose a fabrication method for a buckypaper-filled flexible composite film prepared by a two-step process involving buckypaper fabrication using vacuum filtration of MWCNTs, and composite film fabrication using the dipping method. The thermal conductivity and tensile strength of the composite film filled with the buckypaper exhibited improved results, respectively 76% and 275% greater than those of the individual MWCNT-filled composite film. It was confirmed that forming continuous MWCNT fillers is an important factor which determines the physical characteristics of the composite film. In light of the study findings, composite films using buckypaper as a filler and polydimethylsiloxane (PDMS) as a flexible matrix have sufficient potential to be applied as a heat-dissipating material, and as a flexible film with high thermal conductivity and excellent mechanical properties. PMID:28335310

  6. Effect of Continuous Multi-Walled Carbon Nanotubes on Thermal and Mechanical Properties of Flexible Composite Film.

    PubMed

    Cha, Ji Eun; Kim, Seong Yun; Lee, Seung Hee

    2016-10-12

    To investigate the effect of continuous multi-walled carbon nanotubes (MWCNTs) on the thermal and mechanical properties of composites, we propose a fabrication method for a buckypaper-filled flexible composite film prepared by a two-step process involving buckypaper fabrication using vacuum filtration of MWCNTs, and composite film fabrication using the dipping method. The thermal conductivity and tensile strength of the composite film filled with the buckypaper exhibited improved results, respectively 76% and 275% greater than those of the individual MWCNT-filled composite film. It was confirmed that forming continuous MWCNT fillers is an important factor which determines the physical characteristics of the composite film. In light of the study findings, composite films using buckypaper as a filler and polydimethylsiloxane (PDMS) as a flexible matrix have sufficient potential to be applied as a heat-dissipating material, and as a flexible film with high thermal conductivity and excellent mechanical properties.

  7. Novel Chemoresistive CH4 Sensor with 10 ppm Sensitivity Based on Multi-Walled Carbon Nanotubes (MWCNTs) Functionalized with SnO2nanocrystals

    EPA Science Inventory

    Chemoresistive sensors based on multi-walled carbon nanotubes (MWCNTs)functionalized with SnO2 nanocrystals have great potential for detecting trace gases at low concentrations (single ppm levels) at room temperature, because the SnO2 nanocrystals act as active sites for the chem...

  8. Roles of cation valance and exchange on the retention and colloid-facilitated transport of functionalized multi-walled carbon nanotubes in a natural soil

    USDA-ARS?s Scientific Manuscript database

    Saturated soil column experiments were conducted to investigate the transport, retention, and release behavior of a low concentration (1 mg L-1) of functionalized 14C-labeled multi-walled carbon nanotubes (MWCNTs) in a natural soil under various solution chemistries. Breakthrough curves (BTCs) for M...

  9. Highly efficient bimetal synergetic catalysis by a multi-wall carbon nanotube supported palladium and nickel catalyst for the hydrogen storage of magnesium hydride.

    PubMed

    Yuan, Jianguang; Zhu, Yunfeng; Li, Liquan

    2014-06-25

    A multi-wall carbon nanotube supported Pd and Ni catalyst efficiently catalyzes the hydrogen storage of magnesium hydride prepared by HCS + MM. Excellent hydrogen storage properties were obtained: hydrogen absorption - 6.44 wt% within 100 s at 373 K, hydrogen desorption - 6.41 wt% within 1800 s at 523 K and 6.70 wt% within 400 s at 573 K.

  10. Novel Chemoresistive CH4 Sensor with 10 ppm Sensitivity Based on Multi-Walled Carbon Nanotubes (MWCNTs) Functionalized with SnO2nanocrystals

    EPA Science Inventory

    Chemoresistive sensors based on multi-walled carbon nanotubes (MWCNTs)functionalized with SnO2 nanocrystals have great potential for detecting trace gases at low concentrations (single ppm levels) at room temperature, because the SnO2 nanocrystals act as active sites for the chem...

  11. 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

  12. Amplified electrochemical detection of protein kinase activity based on gold nanoparticles/multi-walled carbon nanotubes nanohybrids.

    PubMed

    Liu, Jinquan; He, Xiaoxiao; Wang, Kemin; Wang, Yonghong; Yan, Genping; Mao, Yinfei

    2014-11-01

    A sensitive and simple electrochemical strategy has been developed for assay of protein kinase A (PKA) activity and inhibition using gold nanoparticles/multi-walled carbon nanotubes (AuNPs/MWNTs) nanohybrids. Key features of this assay included intrinsic peroxidase-like activity of positively-charged gold nanoparticles (+AuNPs) and signal transduction and amplification of multi-walled carbon nanotubes (MWNTs). In this assay, an N-terminally cysteine-containing peptide was self-assembled onto the gold electrode via Au-S bonding and used as substrate for PKA, and adenosine-5'-(γ-thio)-triphosphate was used as co-substrate. Upon thiophosphorylation in the presence of PKA, the AuNPs/MWNTs nanohybrids would be fixed onto the peptides via Au-S bond. The conjugated AuNPs/MWNTs nanohybrids could catalyze the 3, 3', 5, 5'-Tetramethylbenzidine (TMB) oxidation by H2O2 to form TMB oxidation product, which was reduced at the electrode surface to generate an electrochemical current. It was eT on state. The current signal intensity is proportional to the activity of PKA. Here, the presence of MWNTs not only increased the surface area for accumulation of +AuNPs but also could promote electron-transfer reaction. It was found that the electrochemical strategy can be employed to assay PKA activity with a low detection limit of 0.09 U/mL. The linear range of the assay for PKA enzymatic unit/ml was 0.1-1 U/mL. Furthermore, the interferences experiments of T4 polynucleotide kinase (T4 PNK) and Casein kinase II (CK2), and inhibition of PKA, have also been studied by using this strategy. The developed method would provide a diversified platform for kinase activity and inhibition monitoring. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Multi-walled carbon nanotube-induced gene expression in the mouse lung: Association with lung pathology

    SciTech Connect

    Pacurari, M.; Qian, Y.; Porter, D.W.; Wolfarth, M.; Wan, Y.; Luo, D.; Ding, M.; Castranova, V.; Guo, N.L.

    2011-08-15

    Due to the fibrous shape and durability of multi-walled carbon nanotubes (MWCNT), concerns regarding their potential for producing environmental and human health risks, including carcinogenesis, have been raised. This study sought to investigate how previously identified lung cancer prognostic biomarkers and the related cancer signaling pathways are affected in the mouse lung following pharyngeal aspiration of well-dispersed MWCNT. A total of 63 identified lung cancer prognostic biomarker genes and major signaling biomarker genes were analyzed in mouse lungs (n = 80) exposed to 0, 10, 20, 40, or 80 {mu}g of MWCNT by pharyngeal aspiration at 7 and 56 days post-exposure using quantitative PCR assays. At 7 and 56 days post-exposure, a set of 7 genes and a set of 11 genes, respectively, showed differential expression in the lungs of mice exposed to MWCNT vs. the control group. Additionally, these significant genes could separate the control group from the treated group over the time series in a hierarchical gene clustering analysis. Furthermore, 4 genes from these two sets of significant genes, coiled-coil domain containing-99 (Ccdc99), muscle segment homeobox gene-2 (Msx2), nitric oxide synthase-2 (Nos2), and wingless-type inhibitory factor-1 (Wif1), showed significant mRNA expression perturbations at both time points. It was also found that the expression changes of these 4 overlapping genes at 7 days post-exposure were attenuated at 56 days post-exposure. Ingenuity Pathway Analysis (IPA) found that several carcinogenic-related signaling pathways and carcinogenesis itself were associated with both the 7 and 11 gene signatures. Taken together, this study identifies that MWCNT exposure affects a subset of lung cancer biomarkers in mouse lungs. - Research Highlights: > Multi-Walled Carbon Nanotubes affect lung cancer biomarkers in mouse lungs. > The results suggest potentially harmful effects of MWCNT exposure on human lungs. > The results could potentially be used for

  14. Kinetic and isotherm modeling of Cd (II) adsorption by L-cysteine functionalized multi-walled carbon nanotubes as adsorbent.

    PubMed

    Taghavi, Mahmoud; Zazouli, Mohammad Ali; Yousefi, Zabihollah; Akbari-adergani, Behrouz

    2015-11-01

    In this study, multi-walled carbon nanotubes were functionalized by L-cysteine to show the kinetic and isotherm modeling of Cd (II) ions onto L-cysteine functionalized multi-walled carbon nanotubes. The adsorption behavior of Cd (II) ion was studied by varying parameters including dose of L-MWCNTs, contact time, and cadmium concentration. Equilibrium adsorption isotherms and kinetics were also investigated based on Cd (II) adsorption tests. The results showed that an increase in contact time and adsorbent dosage resulted in increase of the adsorption rate. The optimum condition of the Cd (II) removal process was found at pH=7.0, 15 mg/L L-MWCNTs dosage, 6 mg/L cadmium concentration, and contact time of 60 min. The removal percent was equal to 89.56 at optimum condition. Langmuir and Freundlich models were employed to analyze the experimental data. The data showed well fitting with the Langmuir model (R2=0.994) with q max of 43.47 mg/g. Analyzing the kinetic data by the pseudo-first-order and pseudo-second-order equations revealed that the adsorption of cadmium using L-MWSNTs following the pseudo-second-order kinetic model with correlation coefficients (R2) equals to 0.998, 0.992, and 0.998 for 3, 6, and 9 mg/L Cd (II) concentrations, respectively. The experimental data fitted very well with the pseudo-second-order. Overall, treatment of polluted solution to Cd (II) by adsorption process using L-MWCNT can be considered as an effective technology.

  15. 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.

  16. 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.

  17. Dispersion issues and thermal conductivity of polypropylene/multi wall carbon nanotube systems

    NASA Astrophysics Data System (ADS)

    Russo, Pietro; Patti, Antonella; Acierno, Domenico; Acierno, Stefano

    2016-05-01

    Three types of multiwall carbon nanotubes, one non-functionalized tubes and two functionalized with polar (amino and carboxyl) groups, were used as fillers in a polypropylene resin to develop nanocomposites with improved thermal conductivity. In particular, formulations containing up to 5% in volume of carbon nanotubes, prepared by melt blending, were analyzed in terms of dynamic rheological behavior of melts and thermal conductivity. The former can give information related to the build-up of internal network structures and to the level of dispersion of the fillers. Taking into account that the properties of nanocomposites are strictly related to these aspects, the enhancement of thermal conductivity with respect to the pristine matrix are discussed as a function of the filler content, dispersion of the filler and presence of internal structures.

  18. Development of New Photovoltaic Devices Based on Multi Wall Carbon Nanotubes and Nanoparticles

    DTIC Science & Technology

    2013-03-01

    response is registered in all the photon spectral range studied. The new kind of Graetzel-like solar cell device was built without dye and TiO2 , showing...response is registered in all the photon spectral range studied. - The new kind of Graetzel (DSSC, Dye Synthesized Solar Cell ) built without Dye and TiO2 ...an IPCE up to 20%. 15. SUBJECT TERMS EOARD, organic solar cells , photovoltaics, carbon nanotubes 16. SECURITY CLASSIFICATION

  19. 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.

  20. Dispersion of Multi-Walled Carbon Nanotubes by Polymers with Carbazole Pendants.

    PubMed

    Liang, Caizhen; Wang, Bin; Chen, Jianjun; Yong, Qiwen; Huang, Yuewen; Liao, Bing

    2017-09-07

    For various applications, it is essential to enhance the colloidal stabilization of carbon nanotube (CNT) dispersions. Here, the polymers with carbazole pendants of poly(4-(N-carbazolyl)methylstyrene-bl-poly(ethylene glycol) methyl ether methacrylate) (PCMS5-b-PAPEG73 and PCMS16-b-PAPEG43) and PCMS30, synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, were used for noncovalent functionalization of multiwalled carbon nanotubes (MWCNTs) in tetrahydrofuran (THF), offering efficient colloidal stabilization. Meanwhile, the adsorption of polymers onto MWCNTs was investigated. The results showed that the MWCNTs decorated with these three polymers in THF exhibited different colloidal stabilization and adsorption capacity. Moreover, the MWCNT dispersions could be stabilized for days and their colloidal stabilization elevated with the increase of polymer concentrations. The block copolymer PCMS16-b-PAPEG43 exhibited the optimal adsorption and dispersion capability for MWCNTs. These findings imply that PCMSm-b-PAPEGn will be a desirable dispersant for optimizing the stabilization of CNT dispersion, making carbon nanotubes (CNTs) achievable in different applications.

  1. Electrical and mechanical properties as a processing condition in polyvinylchloride multi walled carbon nanotube composites.

    PubMed

    Song, Byung Ju; Ahn, Jin Woo; Cho, Kwon Koo; Roh, Jae Seung; Lee, Dong Yun; Yang, Yong Suk; Lee, Jae Beom; Hwang, Dae Youn; Kim, Hye Sung

    2013-11-01

    We investigated the electrical conductivity (sigma) and mechanical property of polyvinylchloride/carbon nanotube composites as a function of the CNT content and processing time during a solid-state process of high speed vibration mixing (HSVM) and high energy ball milling (HEBM). Both processes were suggested to avoid high temperatures, solvents, chemical modification of carbon nanotubes. In this study, the percolation threshold (phi(c)) for electrical conduction is about 1 wt% CNT with a sigma value of 0.21 S/m, and the electrical conductivity is higher value than that reported by other researchers from melt mixing process or obtained from the other solid-state processes. We found that the dispersion of CNTs and morphology change from CNT breaking are closely related to sigma. Especially, a large morphology change in the CNTs was occurred at the specific processing time, and a significant decrease in the electrical conductivity of polyvinylchloride/carbon nanotube composite occurred in this condition. A meaningful increase of electrical properties and mechanical property is observed in the sample with about 1-2 wt% CNT contents sintered at 200 degrees C after the milling for 20 min by HEBM process. Our study indicates the proper process condition required to improve sigma of PVC/CNT composites.

  2. Fe2O3 Nanoparticles Wrapped in Multi-walled Carbon Nanotubes With Enhanced Lithium Storage Capability

    NASA Astrophysics Data System (ADS)

    Yan, Nan; Zhou, Xuhui; Li, Yan; Wang, Fang; Zhong, Hao; Wang, Hui; Chen, Qianwang

    2013-12-01

    We have designed a novel hybrid nanostructure by coating Fe2O3 nanoparticles with multi-walled carbon nanotubes to enhance the lithium storage capability of Fe2O3. The strategy to prepare Fe2O3@MWCNTs involves the synthesis of Fe nanoparticles wrapped in MWCNTs, followed by the oxidation of Fe nanoparticles under carbon dioxide. When used as the anode in a Li-ion battery, this hybrid material (70.32 wt% carbon nanotubes, 29.68 wt% Fe2O3) showed a reversible discharge capacity of 515 mAhg-1 after 50 cycles at a density of 100 mAg-1 and the capacity based on Fe2O3 nanoparticles was calculated as 1147 mAhg-1, Three factors are responsibile for the superior performance: (1) The hollow interiors of MWCNTs provide enough spaces for the accommodation of large volume expansion of inner Fe2O3 nanoparticles, which can improving the stability of electrode; (2) The MWCNTs increase the overall conductivity of the anode; (3) A stable solid electrolyte interface film formed on the surface of MWCNTs may reduce capacity fading.

  3. Synthesis of multi-wall carbon nanotubes by the pyrolysis of ethanol on Fe/MCM-41 mesoporous molecular sieves

    NASA Astrophysics Data System (ADS)

    Zhao, Qian; Li, Yanhui; Zhou, Xuping; Jiang, Tingshun; Li, Changsheng; Yin, Hengbo

    2010-03-01

    Ordered hexagonal arrangement MCM-41 mesoporous molecular sieves were synthesized by the traditional hydrothermal method, and Fe-loaded MCM-41 mesoporous molecular sieves (Fe/MCM-41) were prepared by the wet impregnation method. Their mesoporous structures were testified by X-ray diffraction (XRD) and the N 2 physical adsorption technique. Carbon nanotubes (CNTs) were synthesized by the chemical vapor deposition (CVD) method via the pyrolysis of ethanol at atmospheric pressure using Fe/MCM-41 as a catalytic template. The effect of different reaction temperatures ranging from 600 to 800 ∘C on the formation of CNTs was investigated. The resulting carbon materials were characterized by various physicochemical techniques such as transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. The results show that multi-wall carbon nanotubes (MWCNTs) with an internal diameter of ca. 7.7 nm and an external diameter of ca. 16.9 nm were successfully obtained by the pyrolysis of ethanol at 800 ∘C utilizing Fe/MCM-41 as a catalytic template.

  4. Highly purified, multi-wall carbon nanotubes induce light-chain 3B expression in human lung cells

    SciTech Connect

    Tsukahara, Tamotsu; Matsuda, Yoshikazu; Usui, Yuki; Haniu, Hisao

    2013-10-18

    Highlights: •HTT2800-treated BEAS-2B cells induced LC3B in a time-dependent manner. •HTT2800-treated BEAS-2B cells showed decreased cell proliferation that was both time- and dose-dependent. •Addition of 3-MA, LC3B-II protein and mRNA levels were significantly decreased. •3-MA and E64-d + pepstatin A, but not brefeldin A, provided protection against HTT2800-induced cell death. •These results suggest that HTT2800 predominantly causes autophagy rather than apoptotic cell death in BEAS-2B cells. -- Abstract: Bronchial epithelial cells are targets of inhalation and play a critical role in the maintenance of mucosal integrity as mechanical barriers against various particles. Our previous result suggest that vapor-grown carbon fiber, HTT2800, which is one of the most highly purified multi-wall carbon nanotubes (MWCNT) showed cellular uptake of the carbon nanotube, increased cell death, enhanced DNA damage, and induced cytokine release. Increasing evidence suggests that autophagy may critically influence vital cellular processes such as apoptosis, cell proliferation and inflammation and thereby may play a critical role in pulmonary diseases. Autophagy was recently recognized as a critical cell death pathway, and autophagosome accumulation has been found to be associated with the exposure of various nanoparticles. In this study, the authors focus on the autophagic responses of HTT2800 exposure. The HTT2800-exposed cells induced LC3B expression and induced cell growth inhibition.

  5. Fe2O3 Nanoparticles Wrapped in Multi-walled Carbon Nanotubes With Enhanced Lithium Storage Capability

    PubMed Central

    Yan, Nan; Zhou, Xuhui; Li, Yan; Wang, Fang; Zhong, Hao; Wang, Hui; Chen, Qianwang

    2013-01-01

    We have designed a novel hybrid nanostructure by coating Fe2O3 nanoparticles with multi-walled carbon nanotubes to enhance the lithium storage capability of Fe2O3. The strategy to prepare Fe2O3@MWCNTs involves the synthesis of Fe nanoparticles wrapped in MWCNTs, followed by the oxidation of Fe nanoparticles under carbon dioxide. When used as the anode in a Li-ion battery, this hybrid material (70.32 wt% carbon nanotubes, 29.68 wt% Fe2O3) showed a reversible discharge capacity of 515 mAhg−1 after 50 cycles at a density of 100 mAg−1 and the capacity based on Fe2O3 nanoparticles was calculated as 1147 mAhg−1, Three factors are responsibile for the superior performance: (1) The hollow interiors of MWCNTs provide enough spaces for the accommodation of large volume expansion of inner Fe2O3 nanoparticles, which can improving the stability of electrode; (2) The MWCNTs increase the overall conductivity of the anode; (3) A stable solid electrolyte interface film formed on the surface of MWCNTs may reduce capacity fading. PMID:24292097

  6. 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

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

    PubMed

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

    2014-07-01

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

  8. Adsorption of Direct Blue 53 dye from aqueous solutions by multi-walled carbon nanotubes and activated carbon.

    PubMed

    Prola, Lizie D T; Machado, Fernando M; Bergmann, Carlos P; de Souza, Felipe E; Gally, Caline R; Lima, Eder C; Adebayo, Matthew A; Dias, Silvio L P; Calvete, Tatiana

    2013-11-30

    Multi-walled carbon nanotubes (MWCNT) and powder activated carbon (PAC) were used as adsorbents for adsorption of Direct Blue 53 dye (DB-53) from aqueous solutions. The adsorbents were characterised using Raman spectroscopy, N2 adsorption/desorption isotherms, and scanning and transmission electron microscopy. The effects of initial pH, contact time and temperature on adsorption capacity of the adsorbents were investigated. At pH 2.0, optimum adsorption of the dye was achieved by both adsorbents. Equilibrium contact times of 3 and 4 h were achieved by MWCNT and PAC adsorbents, respectively. The general order kinetic model provided the best fit of the experimental data compared to pseudo-first order and pseudo-second order kinetic adsorption models. For DB-53 dye, the equilibrium data (298-323 K) were best fitted to the Sips isotherm model. The maximum sorption capacity for adsorption of the dye occurred at 323 K, with the values of 409.4 and 135.2 mg g(-1) for MWCNT and PAC, respectively. Studies of adsorption/desorption were conducted and the results showed that DB-53 loaded MWCNT could be regenerated (97.85%) using a mixture 50% acetone + 50% of 3 mol L(-1) NaOH. Simulated dye house effluents were used to evaluate the application of the adsorbents for effluent treatment (removal of 99.87% and 97.00% for MWCNT and PAC, respectively, were recorded).

  9. A sensitive determination of estrogens with a Pt nano-clusters/multi-walled carbon nanotubes modified glassy carbon electrode.

    PubMed

    Lin, Xiangqin; Li, Yongxin

    2006-08-15

    On the top of a multi-walled carbon nanotubes (MWNTs) modified glassy carbon electrode (MWNTs/GCE), Pt nanoclusters were electrochemically deposited, fabricating a Pt/MWNTs composite modified electrode, Pt/MWNTs/GCE. X-ray photoelectron spectroscopy, powder X-ray diffraction and field emission scanning electron microscope were used for the surface characterization of the electrode, and demonstrated the formation and distribution of Pt clusters of Pt nanoparticles of 8.4 nm in averaged size in the MWNTs matrix. The preliminary study found that this composite modified electrode has strong electrocatalytic activity toward the oxidation of estrogens involving estradiol, estrone and estriol. The voltammetric behavior of estrogens on this electrode was investigated by cyclic voltammetry, linear sweep voltammetry and square-wave voltammetry. In comparison with the MWNTs/GCE or a Pt nanoparticles modified GCE prepared in the similar way, this composite modified electrode exhibited much higher current sensitivity and catalytic activity. This electrode is also stable. The linear range of square-wave voltammetric determination was 5.0 x 10(-7)-1.5 x 10(-5)mol/L for estradiol, 2.0 x 10(-6)-5.0 x 10(-5)mol/L for estrone, and 1.0 x 10(-6)-7.5 x 10(-5)mol/L for estriol. Under an assumption that the concentration ratio of estradiol:estrone:estriol is 2:2:1, the real sample of blood serums was tested for the determination using this electrode. Satisfactory result was obtained with averaged recovery of 105%.

  10. Thin-film electroencephalographic electrodes using multi-walled carbon nanotubes are effective for neurosurgery.

    PubMed

    Awara, Kousuke; Kitai, Ryuhei; Isozaki, Makoto; Neishi, Hiroyuki; Kikuta, Kenichiro; Fushisato, Naoki; Kawamoto, Akira

    2014-12-15

    Intraoperative morphological and functional monitoring is essential for safe neurosurgery. Functional monitoring is based on electroencephalography (EEG), which uses silver electrodes. However, these electrodes generate metal artifacts as silver blocks X-rays, creating white radial lines on computed tomography (CT) images during surgery. Thick electrodes interfere with surgical procedures. Thus, thinner and lighter electrodes are ideal for intraoperative use. The authors developed thin brain electrodes using carbon nanotubes that were formed into thin sheets and connected to electrical wires. The nanotube sheets were soft and fitted the curve of the head very well. When attached to the head using paste, the impedance of the newly developed electrodes was 5 kΩ or lower, which was similar to that of conventional metal electrodes. These electrodes can be used in combination with intraoperative CT, magnetic resonance imaging (MRI), or cerebral angiography. Somatosensory-evoked potentials, auditory brainstem responses, and visually evoked potentials were clearly identified in ten volunteers. The electrodes, without any artifacts that distort images, did not interfere with X-rays, CT, or MR images. They also did not cause skin damage. Carbon nanotube electrodes may be ideal for neurosurgery.

  11. Transformation of multi walled carbon nanotubes irradiated by swift heavy ions

    NASA Astrophysics Data System (ADS)

    Vishalli; Avasthi, D. K.; Srivastava, Alok; Dharamvir, Keya

    2017-09-01

    The radiation stability of multiwalled carbon nanotube (MWCNT) buckypaper (BP) has been studied under extreme conditions. Samples of thick mat of MWCNT, called buckypaper, have been prepared by vacuum filtration method and were irradiated by 120 MeV Au ions with fluences ranging from 3 × 1011 ions/cm2 to 5 × 1013 ions/cm2. The samples were characterized by Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HRTEM) and Raman spectroscopy. The surface imaging studies indicate the decrease in the average diameter of nanotubes under ion irradiation due to the sputtering of atoms from the CNT surface. Raman studies demonstrate initial healing at lower fluence, defect production at higher fluences and amorphization at highest fluence.

  12. 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.

  13. [Study on absorption spectra and optical limiting properties of soluble polymer/multi-walled carbon nanotube composites].

    PubMed

    Qiu, Xue-Qiong; Wu, Hui-Xia; Tong, Rui; Qian, Shi-Xiong; Lin, Yang-Hui; Cai, Rui-Fang

    2008-07-01

    Three kinds of soluble polymer grafted multi-walled carbon nanotubes (MWNTs), including poly(N-vinylcarbazole)-MWNTs (MWNTs-PVK), polystyrene-MWNTs (MWNTs-PSt) and poly(methyl methacrylate)-MWNTs (MWNTs-PMMA) were synthesized. The TEM images of these samples show that polymers are coated outside the carbon nanotubes. The UV-Vis absorption spectra of the samples in CHCl3 were taken on a HP8452 spectrophotometer at room temperature. Compared with that of MWNTs suspension, there is a characteristic absorption peak in the ultraviolet region, which can be attributed to the polymers linked covalently with MWNTs. Their nonlinear optical properties and optical limiting (OL) performances were investigated by Z-scan method with 527 nm nanosecond laser pulses. These MWNTs dissolved in chloroform possess similar optical limiting properties, which are better than that of raw MWNT suspension and C60 in toluene solution. Nonlinear refraction, nonlinear absorption and nonlinear scattering mechanism were taken into consideration for explaining the observed results. The analysis of the experimental results shows that nonlinear absorption is the dominant mechanism behind the OL performance of these samples.

  14. Development of an accurate molecular mechanics model for buckling behavior of multi-walled carbon nanotubes under axial compression.

    PubMed

    Safaei, B; Naseradinmousavi, P; Rahmani, A

    2016-04-01

    In the present paper, an analytical solution based on a molecular mechanics model is developed to evaluate the elastic critical axial buckling strain of chiral multi-walled carbon nanotubes (MWCNTs). To this end, the total potential energy of the system is calculated with the consideration of the both bond stretching and bond angular variations. Density functional theory (DFT) in the form of generalized gradient approximation (GGA) is implemented to evaluate force constants used in the molecular mechanics model. After that, based on the principle of molecular mechanics, explicit expressions are proposed to obtain elastic surface Young's modulus and Poisson's ratio of the single-walled carbon nanotubes corresponding to different types of chirality. Selected numerical results are presented to indicate the influence of the type of chirality, tube diameter, and number of tube walls in detailed. An excellent agreement is found between the present numerical results and those found in the literature which confirms the validity as well as the accuracy of the present closed-form solution. It is found that the value of critical axial buckling strain exhibit significant dependency on the type of chirality and number of tube walls.

  15. Mitochondrial Oxidative Stress and Dysfunction Induced by Single- and Multi-Wall Carbon Nanotubes: A Comparative Study.

    PubMed

    Naserzadeh, Parvaneh; Ghanbary, Fatemeh; Seydi, Enayatollah; Ghasemi, Alireza; Joghataei, Mohammad Taghi; Ashtari, Khadijeh; Akbari, Mohsen

    2017-03-10

    With the ever-increasing use of carbon nanotubes (CNTs) in health-related and engineering applications, the hazardous risks of this material have become a major concern. It is well-known that CNTs accumulate with cytotoxic and genotoxic levels within vital organs. It has also been shown that treating cell cultures with CNTs resulted in cell cycle arrest and increased apoptosis/necrosis. The goal of this pilot study is to perform a comprehensive comparative study on the toxicity of single-wall (SW) and multi-wall (MW) carbon nanotubes in rat skin cells. Our results confirm a dose-dependent toxicity of SWCNT and MWCNT due to the loss of mitochondrial activity, increase in mitochondrial ROS formation and mitochondrial membrane potential (MMP) collapse before mitochondrial swelling. Moreover, disturbance in the oxidative phosphorylation is observed by a decrease in ATP level. These events induced the release of cytochrome c via outer membrane rupture or MPT pore opening and subsequently programmed cell-death of all doses compared to control group. Our results demonstrate that although MWCNT can be very toxic, SWCNT cause more mitochondrial damage to the cells. This article is protected by copyright. All rights reserved.

  16. Drug targeting to arthritic region via folic acid appended surface-engineered multi-walled carbon nanotubes.

    PubMed

    Kayat, Jitendra; Mehra, Neelesh Kumar; Gajbhiye, Virendra; Jain, Narendra Kumar

    2016-01-01

    This study was aimed at developing and investigating folate anchored carbon nanotubes for targeting an anti-arthritic drug, Methotrexate (MTX) to inflammatory arthritic region. The folic acid (FA) was conjugated to amidated multi-walled carbon nanotubes (MWCNTs) and confirmed by Fourier transform infrared (FTIR), (1)H NMR spectroscopy and X-ray diffraction analysis. The MTX was loaded into the pristine and functionalized-MWCNTs and extensively characterized in vitro and in vivo studies. The drug entrapment efficiency was found high in folate conjugated MWCNTs. In vitro drug release in PBS (pH 7.4) from pristine MWCNTs and folate conjugated MWCNTs formulation was found to be 66.35 ± 2.3 and 56.88 ± 1.9% in 24 h, respectively. Folate conjugated MWCNTs significantly increased (p < 0.005) the percentage inhibition of arthritis, biological half-life and volume of distribution of MTX as compared to MTX-loaded naked MWCNTs as well as free MTX. In in vivo biodistribution studies, MTX was found to be significantly higher (p < 0.005) in arthritic joints from folate functionalized MWCNTs as compared to free drug as well as drug-loaded naked MWCNTs. The present outcomes highlights the propensity of drug-loaded functionalized MWCNTs to alter the pharmacokinetics as well as sustained and targeted drug delivery system as well.

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

    NASA Astrophysics Data System (ADS)

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

    2017-06-01

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

  18. Structure, wettability and photocatalytic activity of CO(2) laser sintered TiO(2)/multi-walled carbon nanotube coatings.

    PubMed

    Castro, M R S; Sam, E D; Veith, M; Oliveira, P W

    2008-03-12

    Nanocomposites of titanium dioxide (TiO(2)) and multi-walled carbon nanotubes (MWNTs) were prepared and deposited by sol-gel spin coating on borosilicate substrates and sintered in air at 300 °C for 15 min. Further irradiation of the films with different CO(2) laser intensities (4.3-17 W m(-2)) was carried out in order to crystallize TiO(2) in the anatase form while preserving the MWNT's structure. The laser irradiation changed the crystal structure of the coatings and also affected the wettability and photocatalytic activity of the films. The anatase phase was only observed when a minimum laser intensity of 12.5 W m(-2) was used. The contact angle decreased with the enhancement of the laser intensity. The photocatalytic activity of the films was determined from the degradation of a stearic acid layer deposited on the films. It was observed that the addition of carbon nanotubes themselves increases the photocatalytic activity of TiO(2) films. This efficiency is even improved when high CO(2) laser intensities are used during the sintering of the coatings.

  19. Drosophila embryos as model to assess cellular and developmental toxicity of multi-walled carbon nanotubes (MWCNT) in living organisms.

    PubMed

    Liu, Boyin; Campo, Eva M; Bossing, Torsten

    2014-01-01

    Different toxicity tests for carbon nanotubes (CNT) have been developed to assess their impact on human health and on aquatic and terrestrial animal and plant life. We present a new model, the fruit fly Drosophila embryo offering the opportunity for rapid, inexpensive and detailed analysis of CNTs toxicity during embryonic development. We show that injected DiI labelled multi-walled carbon nanotubes (MWCNTs) become incorporated into cells in early Drosophila embryos, allowing the study of the consequences of cellular uptake of CNTs on cell communication, tissue and organ formation in living embryos. Fluorescently labelled subcellular structures showed that MWCNTs remained cytoplasmic and were excluded from the nucleus. Analysis of developing ectodermal and neural stem cells in MWCNTs injected embryos revealed normal division patterns and differentiation capacity. However, an increase in cell death of ectodermal but not of neural stem cells was observed, indicating stem cell-specific vulnerability to MWCNT exposure. The ease of CNT embryo injections, the possibility of detailed morphological and genomic analysis and the low costs make Drosophila embryos a system of choice to assess potential developmental and cellular effects of CNTs and test their use in future CNT based new therapies including drug delivery.

  20. Effect of single and multi-wall carbon nanotubes on the mechanical properties of Gd-123 superconducting phase

    NASA Astrophysics Data System (ADS)

    Anas, M.; Ebrahim, Shaker; Eldeen, I. G.; Awad, R.; Abou-Aly, A. I.

    2017-10-01

    The influence of single wall carbon nanotubes SWCNTs and multi wall carbon nanotubes MWCNTs on Vickers microhardness of Gd-123 superconducting phase is studied. Samples of type (SWCNTs)x and (MWCNTs)xGdBa2Cu3O7-δ, composite where, 0.0 ≤ x ≤ 0.1 wt.%, are prepared by solid-state reaction technique. The samples are characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM). Moreover the samples are examined by measuring electrical resistivity and Vickers microhardness. The obtained results showed an enhancement in the phase formation and grains connectivity up to 0.06 and 0.08 wt.% for SWCNTs and MWCNTs added samples, respectively. Likewise the superconducting transition temperature Tc was improved at a low content of CNTs but it suppressed for higher concentrations. In addition, the analysis of Vickers microhardness measurements suggests that the most suitable model that describes the behavior of our sample is proportional specimen resistance PSR model.

  1. Estimation of adsorption energy for water molecules on a multi-walled carbon nanotube thin film by measuring electric resistance

    NASA Astrophysics Data System (ADS)

    Kokabu, Takuya; Inoue, Shuhei; Matsumura, Yukihiko

    2016-11-01

    Gas sensors based on carbon nanotube (CNT) films have attracted attention owing to their low power consumption. For further development of these sensors, we need to understand the surface interaction of the films with gas molecules. In our previous research, we investigated the influence of water molecules on the electrical conductance of multi-walled CNT films and explained this phenomenon using a two-layer adsorption model. This work motivated us to measure the adsorption energy of CNT-H2O. In this study, we focused on the first-layer adsorption and investigated the sheet resistance to water vapor pressure at various temperatures using the transmission line method (TLM). The results were fitted to Langmuir adsorption model and the adsorption equilibrium constant was determined. The temperature dependence of the sheet resistance followed a model of fluctuation induced tunneling (FIT), in which the energy barrier at the CNT junction is regarded as the main factor influencing the electrical conductance of the CNT film. The sheet resistance and equilibrium constant decreased as temperature increased. This result was consistent with the adsorption phenomenon. Finally, the adsorption energy was determined to be 0.22-0.31 eV, which is larger than the previously calculated value. It was also reported that the adsorption energy of the gas molecules in the interstitial site between two carbon nanotubes was larger than that on the CNT surface. These results indicate that the CNT junction plays a key role in the detection of gas molecules.

  2. Desorption of 1,3,5-Trichlorobenzene from Multi-Walled Carbon Nanotubes: Impact of Solution Chemistry and Surface Chemistry

    PubMed Central

    Ma, Xingmao; Uddin, Sheikh

    2013-01-01

    The strong affinity of carbon nanotubes (CNTs) to environmental contaminants has raised serious concern that CNTs may function as a carrier of environmental pollutants and lead to contamination in places where the environmental pollutants are not expected. However, this concern will not be realized until the contaminants are desorbed from CNTs. It is well recognized that the desorption of environmental pollutants from pre-laden CNTs varies with the environmental conditions, such as the solution pH and ionic strength. However, comprehensive investigation on the influence of solution chemistry on the desorption process has not been carried out, even though numerous investigations have been conducted to investigate the impact of solution chemistry on the adsorption of environmental pollutants on CNTs. The main objective of this study was to determine the influence of solution chemistry (e.g., pH, ionic strength) and surface functionalization on the desorption of preloaded 1,3,5-trichlorobenzene (1,3,5-TCB) from multi-walled carbon nanotubes (MWNTs). The results suggested that higher pH, ionic strength and natural organic matter in solution generally led to higher desorption of 1,3,5-TCB from MWNTs. However, the extent of change varied at different values of the tested parameters (e.g., pH < 7 vs. pH > 7). In addition, the impact of these parameters varied with MWNTs possessing different surface functional groups, suggesting that surface functionalization could considerably alter the environmental behaviors and impact of MWNTs. PMID:28348336

  3. Effect of anti-biofouling potential of multi-walled carbon nanotubes-filled polydimethylsiloxane composites on pioneer microbial colonization.

    PubMed

    Sun, Yuan; Lang, Yanhe; Sun, Qian; Liang, Shuang; Liu, Yongkang; Zhang, Zhizhou

    2016-09-01

    In this paper, two carbon nanotube (CNT) nanofillers, namely the multi-walled carbon nanotubes (MWCNTs) and the carboxyl-modified MWCNTs (cMWCNTs), were introduced into the polydimethylsiloxane (PDMS) matrix respectively, in order to produce the PDMS composites with reinforced anti-biofouling properties. The anti-biofouling capacity of the silicone-based coatings, including the unfilled PDMS (P0), the MWCNTs-filled PDMS (PM) and the cMWCNTs-filled PDMS (PC), was examined via the field assays conducted in Weihai, China. The effect of different silicone-based coatings on the dynamic variations of the pioneer microbial-community diversity was analyzed using the single-strand conformation polymorphism (SSCP) technique. The PM and PC surfaces have exhibited excellent anti-biofouling properties in contrast to that of the PDMS surface, with extremely low attachment of the early colonizers, such as juvenile invertebrates, seaweeds and algae sporelings. The PM and PC surfaces can effectively prevent biofouling for more than 12 weeks. These combined results suggest that the incorporation of MWCNTs or cMWCNTs into the PDMS matrix can dramatically reinforce its anti-biofouling properties. The SSCP analysis reveals that compared with the PDMS surfaces, the PM and PC surfaces have strong modulating effect on the pioneer prokaryotic and eukaryotic communities, particularly on the colonization of pioneer eukaryotic microbes. The significantly reduced pioneer eukaryotic-community diversity may contribute to the weakening of the subsequent colonization of macrofoulers.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  5. 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.

  6. 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.

  7. Toward safer multi-walled carbon nanotube design: Establishing a statistical model that relates surface charge and embryonic zebrafish mortality.

    PubMed

    Gilbertson, Leanne M; Melnikov, Fjodor; Wehmas, Leah C; Anastas, Paul T; Tanguay, Robert L; Zimmerman, Julie B

    2016-01-01

    Given the increased utility and lack of consensus regarding carbon nanotube (CNT) environmental and human health hazards, there is a growing demand for guidelines that inform safer CNT design. In this study, the zebrafish (Danio rerio) model is utilized as a stable, sensitive biological system to evaluate the bioactivity of systematically modified and comprehensively characterized multi-walled carbon nanotubes (MWNTs). MWNTs were treated with strong acid to introduce oxygen functional groups, which were then systematically thermally reduced and removed using an inert temperature treatment. While 25 phenotypic endpoints were evaluated at 24 and 120 hours post-fertilization (hpf), high mortality at 24 hpf prevented further resolution of the mode of toxicity leading to mortality. Advanced multivariate statistical methods are employed to establish a model that identifies those MWNT physicochemical properties that best estimate the probability of observing an adverse outcome. The physicochemical properties considered in this study include surface charge, percent surface oxygen, dispersed aggregate size and morphology and electrochemical activity. Of the five physicochemical properties, surface charge, quantified as the point of zero charge (PZC), was determined as the best predictor of mortality at 24 hpf. From a design perspective, the identification of this property-hazard relationship establishes a foundation for the development of design guidelines for MWNTs with reduced hazard.

  8. Comparative studies between the influence of single- and multi-walled carbon nanotubes addition on Gd-123 superconducting phase

    NASA Astrophysics Data System (ADS)

    Abou-Aly, A. I.; Anas, M.; Ebrahim, Shaker; Awad, R.; Eldeen, I. G.

    2016-12-01

    The effect of single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) addition on the phase formation and the superconducting properties of GdBa2Cu3O7-δ phase has been studied. Therefore, composite superconductor samples of type (CNTs)x GdBa2Cu3O7-δ, 0.0 ≤ x ≤ 0.1 wt.% have been synthesized by a standard solid-state reaction technique. The samples have been characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results of XRD show an enhancement in the phase formation up to 0.06 wt.% and 0.08 wt.% for SWCNTs and MWCNTs, respectively. SEM and TEM reveal that CNTs form an electrical network resulting in well-connected superconducting grains. The electrical properties of the prepared samples have been examined by electric resistivity and I-V measurements, and their results reinforce the XRD, SEM and TEM. Consequently, both Tc and Jc improve as the addition percentage increases up to 0.06 wt.% and 0.08 wt.% for SWCNTs and MWCNTs, respectively.

  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. Role of multiwalled carbon nanotube in interlaminar shear strength of epoxy/glass fiber/multi walled carbon nanotube hybrid composites

    NASA Astrophysics Data System (ADS)

    Srinivasan Chandrasekaran, Vasan Churchill

    2011-12-01

    The motivation of this thesis is to investigate the role of multi-walled carbon nanotube (MWCNT) in enhancing the interlaminar shear strength (ILSS) of hybrid composites. The objective of this thesis is to understand the relationships between processing history, material variability, matrix properties, glass fiber/matrix interface properties and their correlations with interlaminar shear strength of hybrid composites. The interlaminar shear strength (ILSS) of hybrid composites made from glass fiber and multi-walled carbon nanotube (MWCNT) modified epoxy is compared with that for unmodified epoxy/glass fiber composites (control). By combining the techniques of high speed mechanical stirring and ultrasonic agitation, 0.5% MWCNT by weight were dispersed in epoxy to prepare a suspension. Composites were manufactured by both injection double vacuum-assisted resin transfer molding (IDVARTM) and the flow flooding chamber (FFC) methods. Compression shear tests (CST) were conducted on the manufactured samples to determine the ILSS. The effect of processing history and batch-to-batch variability of materials---glass fiber preform, resin and carbon nanotubes---on the ILSS of samples made by both techniques was investigated. Statistical comparison of the measured ILSS values for hybrid composites with the control specimens clearly show that hybrid composites made by the FFC process resulted in significant ILSS enhancement relative to the control and the IDVARTM specimens. After it was established that the FFC process improved the ILSS, the effect of functionalizing the nanotubes was explored. Multi walled carbon nanotubes (MWCNT) were oxidized by acid treatment and heated with triethylene tetra amine (TETA) to obtain amino functionalized MWCNTs (f-MWCNT). Hybrid composites with f-MWCNTs were manufactured using FFC technique and control samples were fabricated using the same E-Glass fiber mat and unmodified epoxy resin subjected to the same processing history. CST results show

  11. Dynamics of capillary infiltration of liquids into a highly aligned multi-walled carbon nanotube film.

    PubMed

    Boncel, Sławomir; Walczak, Krzysztof Z; Koziol, Krzysztof K K

    2011-01-01

    The physical compatibility of a highly aligned carbon nanotube (HACNT) film with liquids was established using a fast and convenient experimental protocol. Two parameters were found to be decisive for the infiltration process. For a given density of nanotube packing, the thermodynamics of the infiltration process (wettability) were described by the contact angle between the nanotube wall and a liquid meniscus (θ). Once the wettability criterion (θ < 90°) was met, the HACNT film (of free volume equal to 91%) was penetrated gradually by the liquid in a rate that can be linearly correlated to dynamic viscosity of the liquid (η). The experimental results follow the classical theory of capillarity for a steady process (Lucas-Washburn law), where the nanoscale capillary force, here supported by gravity, is compensated by viscous drag. This most general theory of capillarity can be applied in a prediction of both wettability of HACNT films and the dynamics of capillary rise in the intertube space in various technological applications.

  12. Dynamics of capillary infiltration of liquids into a highly aligned multi-walled carbon nanotube film

    PubMed Central

    Walczak, Krzysztof Z; Koziol, Krzysztof K K

    2011-01-01

    Summary The physical compatibility of a highly aligned carbon nanotube (HACNT) film with liquids was established using a fast and convenient experimental protocol. Two parameters were found to be decisive for the infiltration process. For a given density of nanotube packing, the thermodynamics of the infiltration process (wettability) were described by the contact angle between the nanotube wall and a liquid meniscus (θ). Once the wettability criterion (θ < 90°) was met, the HACNT film (of free volume equal to 91%) was penetrated gradually by the liquid in a rate that can be linearly correlated to dynamic viscosity of the liquid (η). The experimental results follow the classical theory of capillarity for a steady process (Lucas–Washburn law), where the nanoscale capillary force, here supported by gravity, is compensated by viscous drag. This most general theory of capillarity can be applied in a prediction of both wettability of HACNT films and the dynamics of capillary rise in the intertube space in various technological applications. PMID:21977444

  13. Gold nanoparticle/multi-walled carbon nanotube modified glassy carbon electrode as a sensitive voltammetric sensor for the determination of diclofenac sodium.

    PubMed

    Afkhami, Abbas; Bahiraei, Atousa; Madrakian, Tayyebeh

    2016-02-01

    A simple and highly sensitive sensor for the determination of diclofenac sodium based on gold nanoparticle/multi-walled carbon nanotube modified glassy carbon electrode is reported. Scanning electron microscopy along with energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, cyclic voltammetry and square wave voltammetry was used to characterize the nanostructure and performance of the sensor and the results were compared with those obtained at the multi-walled carbon nanotube modified glassy carbon electrode and bare glassy carbon electrode. Under the optimized experimental conditions diclofenac sodium gave linear response over the range of 0.03-200μmolL(-1). The lower detection limits were found to be 0.02μmolL(-1). The effect of common interferences on the current response of DS was investigated. The practical application of the modified electrode was demonstrated by measuring the concentration of diclofenac sodium in urine and pharmaceutical samples. This revealed that the gold nanoparticle/multiwalled carbon nanotube modified glassy carbon electrode shows excellent analytical performance for the determination of diclofenac sodium in terms of a very low detection limit, high sensitivity, very good accuracy, repeatability and reproducibility. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Composites of multi-walled carbon nanotubes with polypropylene and thermoplastic olefin blends prepared by melt compounding

    NASA Astrophysics Data System (ADS)

    Petrie, Kyle G.

    Composites of multi-walled carbon nanotubes (MWCNTs) with polypropylene (PP) and thermoplastic olefins (TPOs) were prepared by melt compounding. Two non-covalent functionalization methods were employed to improve nanotube dispersion and the resulting composite properties are reported. The first functionalization approach involved partial coating of the surface of the nanotubes with a hyperbranched polyethylene (HBPE). MWCNT functionalization with HBPE was only moderately successful in breaking up the large aggregates that formed upon melt mixing with PP. In spite of the formation of large aggregates, the samples were conductive above a percolation threshold of 7.3 wt%. MWCNT functionalization did not disrupt the electrical conductivity of the nanotubes. The composite strength was improved with addition of nanotubes, but ductility was severely compromised because of the existence of aggregates. The second method involved PP matrix functionalization with aromatic moieties capable of pi-pi interaction with MWCNT sidewalls. Various microscopy techniques revealed the addition of only 25 wt% of PP-g-pyridine (Py) to the neat PP was capable of drastically reducing nanotube aggregate size and amount. Raman spectroscopy confirmed improved polymer/nanotube interaction with the PP-g-Py matrix. Electrical percolation threshold was obtained at a MWCNT loading of approximately 1.2 wt%. Electrical conductivity on the order of 10 -2 S/m was achieved, suggesting possible use in semi-conducting applications. Composite strength was improved upon addition of MWCNTs. The matrix functionalization with Py resulted in a significant improvement in composite ductility when filled with MWCNTs in comparison to its maleic anhydride (MA) counterpart. Preliminary investigations suggest that the use of alternating current (AC) electric fields may be effective in aligning nanotubes in PP to reduce the filler loading required for electrical percolation. Composites containing MWCNT within PP

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed

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

    2014-12-12

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

  17. Aqueous adsorption of aniline, phenol, and their substitutes by multi-walled carbon nanotubes.

    PubMed

    Yang, Kun; Wu, Wenhao; Jing, Qingfeng; Zhu, Lizhong

    2008-11-01

    Aqueous adsorption of a series of phenols and anilines by a multiwalled carbon nanotube material (MWCNT15), which depends strongly on the solution pH and the number and types of solute groups, was investigated in this study. The pH-dependent adsorption coefficients, Kd, could be predicted by the established models including solute pKa and solution pH values. Phenol or aniline substitution with more groups has higher adsorption affinity, and nitro, chloride, or methyl groups enhanced adsorption in the following order: nitro group > chloride group > methyl group. All adsorption isotherms of nondissociated phenols and anilines are nonlinear and fitted well bythe Polanyi-theory based Dubinin-Ashtakhov (DA) model. Linear quantitative relationships combining DA model parameters (E and b) with solute solvatochromic parameters were developed to evaluate the adsorptive behaviors of nondissociated species. For the saturated sorbed capacity, Q0, the logarithmic values of phenols and anilines were relatively constant with a mean value of 1.90. Besides the van der Waals force, H-bonding interactions from solutes as hydrogen-bonding donors, and followed by pi-electron polarizability, may play important roles on the adsorption of phenols and anilines by carbon nanotubes in the aqueous environment

  18. Dispersion of multi-wall carbon nanotubes in polyhistidine: characterization and analytical applications.

    PubMed

    Dalmasso, Pablo R; Pedano, María L; Rivas, Gustavo A

    2012-01-13

    We report for the first time the use of polyhistidine (Polyhis) to efficiently disperse multiwall carbon nanotubes (MWCNTs). The optimum dispersion MWCNT-Polyhis was obtained by sonicating for 30 min 1.0 mg mL(-1) MWCNTs in 0.25 mg mL(-1) Polyhis solution prepared in 75:25 (v/v) ethanol/0.200 M acetate buffer solution pH 5.00. The dispersion was characterized by scanning electron microscopy, and by cyclic voltammetry and amperometry using ascorbic acid as redox marker. The modification of glassy carbon electrodes with MWCNT-Polyhis produces a drastic decrease in the overvoltage for the oxidation of ascorbic acid (580 mV) at variance with the response observed at glassy carbon electrodes modified just with Polyhis, where the charge transfer is more difficult due to the blocking effect of the polymer. The reproducibility for the sensitivities obtained after 10 successive calibration plots using the same surface was 6.3%. The MWCNT-modified glassy carbon electrode demonstrated to be highly stable since after 45 days storage at room temperature the response was 94.0% of the original. The glassy carbon electrode modified with MWCNT-Polyhis dispersion was successfully used to quantify dopamine or uric acid at nanomolar levels, even in the presence of large excess of ascorbic acid. Determinations of uric acid in human blood serum samples demonstrated a very good correlation with the value reported by Wienner laboratory.

  19. Effects of multi-walled carbon nanotubes on rheological and physical properties of polyamide-based thermoplastic elastomers

    NASA Astrophysics Data System (ADS)

    Bae, Won-Sik; Kwon, Oh Joo; Kim, Byoung Chul; Chae, Dong Wook

    2012-09-01

    The polyamide-based thermoplastic elastomers (Pebax®) were melt compounded with multi-walled carbon nanotubes (MWNTs: 0.25˜5 wt%) and the variation of rheological and physical properties with MWNT contents was investigated. The crystallization temperature (Tc) of the nanocomposites with 0.5 wt% MWNTs was most increased by ca. 8oC, but it was decreased by further addition. In addition, the presence of MWNTs broadened the Tc peak with increasing nanotube contents. In contrast, the melting behavior was little influenced by the presence of MWNTs for all compositions. The incorporation of MWNTs increased the complex viscosity with MWNT contents and the abrupt increase was observed from 1 wt%. In addition, lower Newtonian flow region became disappearing with increasing MWNT contents, exhibiting notable shear thinning behavior from 1 wt% loading. Storage modulus was increased with MWNT contents in a similar manner to viscosity. Casson plot demonstrated a non-zero positive intercept for all the samples. In particular, the abrupt increase of yield stress was observed from 1 wt% loading. In the Cole-Cole plot, the nanocomposites gave a deviated curve from pure Pebax and the slope was decreased with increasing MWNT contents. The relaxation time calculated from viscoelastic parameters was increased with nanotube contents, but the increasing extents were reduced with increasing frequency. From 2 wt% MWNTs, the electrical conductivity was observed, indicating that the electrical percolation existed between 1.5 and 2 wt%. At 0.25 wt% loading the tensile strength was slightly increased, but it was gradually decreased by further addition. The introduction of MWNTs increased the tensile modulus with nanotube contents. In addition, ductile properties were reduced with increasing MWNT contents, resulting in low toughness.

  20. Enhanced electrical conductivity and hardness of silver-nickel composites by silver-coated multi-walled carbon nanotubes.

    PubMed

    Lee, Dongmok; Sim, Jeonghyun; Kim, Wonyoung; Moon, Chuldong; Cho, Wookdong; Baik, Seunghyun

    2015-07-24

    We investigated electrical conductivity and Vickers hardness of Ag- and Ni-based composites prepared by powder metallurgy involving spark plasma sintering. The starting composition was Ag:Ni = 61:39 vol%, which provided an electrical conductivity of 3.30 × 10(5) S cm(-1) and a hardness of 1.27 GPa. The addition of bare multi-walled carbon nanotubes (MWNTs, 1.45 vol%) increased hardness (1.31 GPa) but decreased electrical conductivity (2.99 × 10(5) S cm(-1)) and carrier mobility (11 cm(2) V(-1) s(-1)) due to the formation of Ni3C in the interface between the MWNTs and Ni during spark plasma sintering. The formation of Ni3C was prevented by coating the surface of the nanotubes with Ag (nAgMWNTs), concomitantly increasing electrical conductivity (3.43 × 10(5) S cm(-1)) and hardness (1.37 GPa) of the sintered specimen (Ag:Ni:nAgMWNTs = 59.55:39:1.45 vol%). The electrical contact switching time (133 357) was also increased by 30%, demonstrating excellent feasibility as electrical contact materials for electric power industries.

  1. The impact of multi-walled carbon nanotubes with different amount of metallic impurities on immunometabolic parameters in healthy volunteers.

    PubMed

    Vitkina, T I; Yankova, V I; Gvozdenko, T A; Kuznetsov, V L; Krasnikov, D V; Nazarenko, A V; Chaika, V V; Smagin, S V; Tsatsakis, A Μ; Engin, A B; Karakitsios, S P; Sarigiannis, D A; Golokhvast, K S

    2016-01-01

    The impact of two types of multi-walled carbon nanotubes (MWCNTs) (12-14 nm) with different content of metallic impurities (purified and unpurified nanotubes) on peroxidation processes, the status of immune cells in healthy volunteers and gene expression combined to pathway analysis was studied in vitro. From the study it was shown that the main mechanism of action for both types of MWCNTs is induction of oxidative stress, the intensity of which is directly related to the amount of metallic impurities. Unpurified MWCNTs produced twice as high levels of oxidation than the purified CNTs inducing thus more intense mitochondrial dysfunction. All the above were also verified by gene expression analysis of 2 different human cellular cultures (lung epithelium and keratinoma cells) and the respective pathway analysis; modulation of genes activating the NFkB pathway is associated to inflammatory responses. This may cause a perturbation in the IL-6 signaling pathway in order to regulate inflammatory processes and compensate for apoptotic changes. A plausible hypothesis for the immunological effects observed in vivo, are considered as the result of the synergistic effect of systemic (mediated by cells of the routes of exposure) and local inflammation (blood cells). Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Description of Chemically and Thermally Treated Multi-Walled Carbon Nanotubes Using Sequential Decomposition of Adsorption Isotherms

    NASA Astrophysics Data System (ADS)

    Albesa, Alberto G.; Rafti, Matías; Vicente, José Luis

    2016-03-01

    The effect of wet acid oxidation by means of sulfuric/nitric acid mixtures, and high-temperature treatment of commercial arc-discharge synthesized multi-walled carbon nanotubes (MWCNTs) was studied. In order to analyze the adsorption capacities of differently treated MWCNTs, we employed a multistep method that considers separately different pressure ranges (zones) on the experimentally obtained isotherms. The method is based on simple gas isotherm measurements (N2, CO2, CH4, etc.). Low pressure ranges can be described using Dubinin’s model, while high pressure regimes can be fitted using different models such as BET multilayer and Freundlich equations. This analysis allows to elucidate how different substrate treatments (chemical and thermal) can affect the adsorbate-adsorbent interactions; moreover, theoretical description of adsorbate-adsorbate interactions can be improved if a combination of adsorption mechanisms are used instead of a unique model. The results hereby presented also show that, while MWCNTs are a promising material for storage applications, gas separation applications should carefully consider the effect of wide nanotube size distribution present on samples after activation procedures.

  3. Mechanical properties of multi-walled carbon nanotube (MWCNT)/polymethyl methacrylite (PMMA) nanocomposite prepared via the coagulation method

    NASA Astrophysics Data System (ADS)

    Ismail, Noor Mazni; Aziz, Azizan; Jaafar, Mariatti

    2012-06-01

    Multi-walled carbon nanotube (MWCNT) is well known as one of the best candidates for reinforcing the next generation of high performance nanocomposites due to its excellent mechanical properties. In this study, MWCNTs were dispersed in polymethyl methacrylite (PMMA) matrix to enhance its mechanical strength. MWCNT/PMMA were prepared by simple coagulation method and then hot-pressed to create nanocomposite film consists of rich nanotubes. Samples were prepared in respect to various high filler loading (1%, 3%, 5%, 7% and 10% wt.). Standard ASTM D790 flexural test was used to evaluate the mechanical properties of the composites. The morphology and surface fracture were observed via scanning electron microscope. The properties of the composites where found to be better than the neat PMMA. Flexural strength & flexural modulus of MWCNT/PMMA nanocomposite showed an improvement up to 24.1% and 107.7% compared to the neat PMMA, respectively. These studies therefore demonstrate that MWCNT/PMMA prepared by coagulation method able to successfully improve mechanical properties of PMMA.

  4. 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.

  5. LSER model for organic compounds adsorption by single-walled carbon nanotubes: Comparison with multi-walled carbon nanotubes and activated carbon.

    PubMed

    Yu, Xiangquan; Sun, Weiling; Ni, Jinren

    2015-11-01

    LSER models for organic compounds adsorption by single and multi-walled carbon nanotubes and activated carbon were successfully developed. The cavity formation and dispersion interactions (vV), hydrogen bond acidity interactions (bB) and π-/n-electron interactions (eE) are the most influential adsorption mechanisms. SWCNTs is more polarizable, less polar, more hydrophobic, and has weaker hydrogen bond accepting and donating abilities than MWCNTs and AC. Compared with SWCNTs and MWCNTs, AC has much less hydrophobic and less hydrophilic adsorption sites. The regression coefficients (e, s, a, b, v) vary in different ways with increasing chemical saturation. Nonspecific interactions (represented by eE and vV) have great positive contribution to organic compounds adsorption, and follow the order of SWCNTs > MWCNTs > AC, while hydrogen bond interactions (represented by aA and bB) demonstrate negative contribution. These models will be valuable for understanding adsorption mechanisms, comparing adsorbent characteristics, and selecting the proper adsorbents for certain organic compounds.

  6. Effects of multi-walled carbon nanotubes on mineralization and mobility of nonylphenol and sodium dodecyl sulfate in agricultural soils

    NASA Astrophysics Data System (ADS)

    Lillotte, Julia; Marschner, Bernd; Stumpe, Britta

    2014-05-01

    Nanotechnology is one of the major scientific research fields in this decade. One of the most wide-spread nanomaterials are carbon based nanoparticles (CNPs) which are increasingly be used in industry. Several studies shows that CNPs are interacting with other chemical compounds and organic pollutants in the environment. It is assumed that the interactions between CNPs and organic pollutants are affected by solution and aggregate behavior. Based on the knowledge of the behavior of CNPs and organic pollutants in aquatic systems the interactions of CNPs and organic pollutants in agricultural soils have to be studied. As organic pollutants two environmental substances, nonylphenol (NP) and sodium dodecyl sulfate (SDS) were selected as model substances. They occur frequently in aqueous systems and also show different solubility behavior. As CNP representatives, two different multi-walled carbon nanotubes (MWNT) were selected. They differed either in length or outer diameter. Conclusions therefrom are to be closed the influence of length and diameter of the sorption capacity of different organic pollutants. In addition, two agricultural soils (sandy and silty soil) and one forest soil (sandy soil) were chosen. Mineralization and sorption experiments were conducted to provide information about the degradation of organic pollutants in presence of multi-walled carbon nanotubes in soils. To analyze the CNPs mineralization potential, peroxidase activity was measured. Further extraction experiments were conducted to detect the extractable part of organic pollutants. The results show that the surface area of the MWNT has a significant impact on the sorption behav-ior of NP and SDS in soils. The sorption of NP and SDS is much higher than without MWNT. However, the properties of the organic pollutants (different water solubility and hydrophobicity) are equally important and should be noted. The degradation of both pollutants is influenced by MWNT. Due to the strong sorption of

  7. Synthesis of Multi-Walled Carbon Nanotubes from Plastic Waste Using a Stainless-Steel CVD Reactor as Catalyst.

    PubMed

    Tripathi, Pranav K; Durbach, Shane; Coville, Neil J

    2017-09-22

    The disposal of non-biodegradable plastic waste without further upgrading/downgrading is not environmentally acceptable and many methods to overcome the problem have been proposed. Herein we indicate a simple method to make high-value nanomaterials from plastic waste as a partial solution to the environmental problem. Laboratory-based waste centrifuge tubes made of polypropylene were chosen as a carbon source to show the process principle. In the process, multi-walled carbon nanotubes (MWCNTs) were synthesized from plastic waste in a two-stage stainless steel 316 (SS 316) metal tube that acted as both reactor vessel and catalyst. The steel reactor contains Fe (and Ni, and various alloys), which act as the catalyst for the carbon conversion process. The reaction and products were studied using electron probe microanalysis, thermogravimetric analysis, Raman spectroscopy and transmission electron microscopy and scanning electron microscopy. Optimization studies to determine the effect of different parameters on the process showed that the highest yield and most graphitized MWCNTs were formed at 900 °C under the reaction conditions used (yield 42%; Raman ID/IG ratio = 0.48). The high quality and high yield of the MWCNTs that were produced in a flow reactor from plastic waste using a two stage SS 316 chemical vapor deposition (CVD) furnace did not require the use of an added catalyst.

  8. 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.

  9. Polyurethane foam with multi walled carbon nanotubes/magnesium hybrid filler

    NASA Astrophysics Data System (ADS)

    Adnan, Sinar Arzuria; Zainuddin, Firuz; Zaidi, Nur Hidayah Ahmad; Akil, Hazizan Md.; Ahmad, Sahrim

    2016-07-01

    The purpose of this paper is to investigate the effect of multiwalled carbon nanotubes (MWCNTs)/magnesium (Mg) hybrid filler in polyurethane (PU) foams with different weight percentages (0.5 wt.% to 3.0 wt.%). The PU/MWCNTs/Mg foam composites were formed by reaction of based palm oil polyol (POP) with methylene diphenyl diisocyanate (MDI) with ratio 1:1.1 by weight. The foam properties were evaluated in density, morphology and compressive strength. The addition of 2.5 wt.% hybrid filler showed the higher density in 59.72 kg/m3 and thus contribute to the highest compressive strength at 1.76 MPa. The morphology show cell in closed structure and addition hybrid filler showed uneven structure.

  10. Electrocatalyzed O2 response of myoglobin immobilized on multi-walled carbon nanotube forest electrodes.

    PubMed

    Pacios, M; del Valle, M; Bartroli, J; Esplandiu, M J

    2009-10-01

    Direct electrochemistry and activity of myoglobin (Mb) immobilized on carbon nanotube (CNT) forest electrodes were investigated by probing mainly its electrocatalytical response towards oxygen. The protein was anchored on the CNT electrodes through carbodiimide coupling, which was shown to provide long term stability. The electrochemical response was monitored as a function of oxygen concentration and pH. Conformational changes together with the consequent loss of oxygen affinity were recorded at low pH, which delimits the operative range of the Mb/CNT electrodes for sensing purposes. In general, it can be concluded that CNT forests constitute suitable platforms for Mb attachment without compromising the protein bioactivity and by keeping at the same time the direct electron exchange with the heme core. All these characteristics confer to the protein modified CNT system promising properties for the implementation of (bio)sensor devices with impact in the clinical and environmental field.

  11. Scribable multi-walled carbon nanotube-silicon nanocomposites: a viable lithium-ion battery system.

    PubMed

    Epur, Rigved; Ramanathan, Madhumati; Datta, Moni K; Hong, Dae Ho; Jampani, Prashanth H; Gattu, Bharat; Kumta, Prashant N

    2015-02-28

    A novel electrode fabrication technique involving a manual scribing action of vertically aligned silicon coated multiwall carbon nanotubes (VASCNTs) on a copper foil have been developed as a viable approach to Li-ion battery electrodes. The scribed electrodes were prepared without the use of any conductive additives and binders, and they were directly assembled in a coin cell. These 'binder-less' scribed Si-CNT electrodes exhibited a very high discharge capacity in excess of 3000 mA h g(-1) and a low first cycle irreversible loss (FIR) (19%). In addition, the electrodes also showed good cyclability with capacity retention of 76% at the end of 50 cycles corresponding to a fade rate of 0.48% loss per cycle rendering the technique attractive for suitable Li-ion applications.

  12. In vivo translocation and toxicity of multi-walled carbon nanotubes are regulated by microRNAs

    NASA Astrophysics Data System (ADS)

    Zhao, Yunli; Wu, Qiuli; Li, Yiping; Nouara, Abdelli; Jia, Ruhan; Wang, Dayong

    2014-03-01

    We employed an in vivo Caenorhabditis elegans assay system to perform SOLiD sequencing analysis to identify the possible microRNA (miRNA) targets of multi-walled carbon nanotubes (MWCNTs). Bioinformatics analysis on targeted genes for the identified dysregulated miRNAs in MWCNT exposed nematodes demonstrates their involvement in many aspects of biological processes. We used loss-of-function mutants for the identified dysregulated miRNAs to perform toxicity assessment by evaluating functions of primary and secondary targeted organs, and found the miRNA mutants with susceptible or resistant property towards MWCNT toxicity. Both the physiological state of the intestine and defecation behavior were involved in the control of the susceptible or resistant property occurrence for specific miRNA mutants towards MWCNT toxicity. This work provides the molecular basis at the miRNA level for future chemical design to reduce the nanotoxicity of MWCNTs and further elucidation of the related toxicological mechanism.We employed an in vivo Caenorhabditis elegans assay system to perform SOLiD sequencing analysis to identify the possible microRNA (miRNA) targets of multi-walled carbon nanotubes (MWCNTs). Bioinformatics analysis on targeted genes for the identified dysregulated miRNAs in MWCNT exposed nematodes demonstrates their involvement in many aspects of biological processes. We used loss-of-function mutants for the identified dysregulated miRNAs to perform toxicity assessment by evaluating functions of primary and secondary targeted organs, and found the miRNA mutants with susceptible or resistant property towards MWCNT toxicity. Both the physiological state of the intestine and defecation behavior were involved in the control of the susceptible or resistant property occurrence for specific miRNA mutants towards MWCNT toxicity. This work provides the molecular basis at the miRNA level for future chemical design to reduce the nanotoxicity of MWCNTs and further elucidation of the

  13. Nitrative DNA damage induced by multi-walled carbon nanotube via endocytosis in human lung epithelial cells

    SciTech Connect

    Guo, Feiye; Ma, Ning; Horibe, Yoshiteru; Kawanishi, Shosuke; Murata, Mariko; Hiraku, Yusuke

    2012-04-15

    Carbon nanotube (CNT) has a promising usage in the field of material science for industrial purposes because of its unique physicochemical property. However, intraperitoneal administration of CNT was reported to cause mesothelioma in experimental animals. Chronic inflammation may contribute to carcinogenesis induced by fibrous materials. 8-Nitroguanine is a mutagenic DNA lesion formed during inflammation and may play a role in CNT-induced carcinogenesis. In this study, we examined 8-nitroguanine formation in A549 human lung alveolar epithelial cells treated with multi-walled CNT (MWCNT) by fluorescent immunocytochemistry. Both MWCNTs with diameter of 20–30 nm (CNT20) and 40–70 nm (CNT40) significantly induced 8-nitroguanine formation at 5 and 10 μg/ml (p < 0.05), which persisted for 24 h, although there was no significant difference in DNA-damaging abilities of these MWCNTs. MWCNTs significantly induced the expression of inducible nitric oxide synthase (iNOS) for 24 h (p < 0.05). MWCNTs also significantly increased the level of nitrite, a hydrolysis product of oxidized NO, in the culture supernatant at 4 and 8 h (p < 0.05). MWCNT-induced 8-nitroguanine formation and iNOS expression were largely suppressed by inhibitors of iNOS (1400 W), nuclear factor-κB (Bay11-7082), actin polymerization (cytochalasin D), caveolae-mediated endocytosis (methyl-β-cyclodextrin, MBCD) and clathrin-mediated endocytosis (monodansylcadaverine, MDC). Electron microscopy revealed that MWCNT was mainly located in vesicular structures in the cytoplasm, and its cellular internalization was reduced by MBCD and MDC. These results suggest that MWCNT is internalized into cells via clathrin- and caveolae-mediated endocytosis, leading to inflammatory reactions including iNOS expression and resulting nitrative DNA damage, which may contribute to carcinogenesis. Highlights: ►Multi-walled carbon nanotube (MWCNT) caused DNA damage in A549 cells. ►MWCNT formed 8-nitroguanine, a DNA lesion

  14. Aerosol Emission Monitoring and Assessment of Potential Exposure to Multi-walled Carbon Nanotubes in the Manufacture of Polymer Nanocomposites

    PubMed Central

    Thompson, Drew; Chen, Sheng-Chieh; Wang, Jing; Pui, David Y.H.

    2015-01-01

    Recent animal studies have shown that carbon nanotubes (CNTs) may pose a significant health risk to those exposed in the workplace. To further understand this potential risk, effort must be taken to measure the occupational exposure to CNTs. Results from an assessment of potential exposure to multi-walled carbon nanotubes (MWCNTs) conducted at an industrial facility where polymer nanocomposites were manufactured by an extrusion process are presented. Exposure to MWCNTs was quantified by the thermal-optical analysis for elemental carbon (EC) of respirable dust collected by personal sampling. All personal respirable samples collected (n = 8) had estimated 8-h time weighted average (TWA) EC concentrations below the limit of detection for the analysis which was about one-half of the recommended exposure limit for CNTs, 1 µg EC/m3 as an 8-h TWA respirable mass concentration. Potential exposure sources were identified and characterized by direct-reading instruments and area sampling. Area samples analyzed for EC yielded quantifiable mass concentrations inside an enclosure where unbound MWCNTs were handled and near a pelletizer where nanocomposite was cut, while those analyzed by electron microscopy detected the presence of MWCNTs at six locations throughout the facility. Through size selective area sampling it was identified that the airborne MWCNTs present in the workplace were in the form of large agglomerates. This was confirmed by electron microscopy where most of the MWCNT structures observed were in the form of micrometer-sized ropey agglomerates. However, a small fraction of single, free MWCNTs was also observed. It was found that the high number concentrations of nanoparticles, ~200000 particles/cm3, present in the manufacturing facility were likely attributable to polymer fumes produced in the extrusion process. PMID:26209597

  15. Flame synthesis of multi-walled carbon nanotubes using CH{sub 4}-H{sub 2} fuel blends

    SciTech Connect

    Manciu, F.S.; Camacho, J.; Choudhuri, A.R.

    2008-07-01

    Flame synthesis of carbon nanotubes (CNTs) has the potential to become a cost effective, energy efficient and scalable method for large-volume commercial synthesis. The in-flame concentration of key particulate inception intermediates, i.e., CH{sub 3}, C{sub 2}H{sub 2}, C{sub 3}H{sub 3}, and C{sub 5}H{sub 5} can be tailored using hydrogen fuel blends to optimize and enhance the yield of flame synthesis processes. Additionally, synthesis of CNTs using hydrogen fuel blends (coal or biomass derived gases) creates new opportunities for efficient coal utilization and by-product synergism of coal-fired power plants. This article reports an investigation on the synthesis of CNTs using H{sub 2} doped CH{sub 4} flames. For a baseline study, nanostructures formed in diffusion flames of 100% CH{sub 4} at different fuel flow rates have been analyzed. Initially the yield of nanomaterials increases with the increase in H{sub 2} doping in the fuel mixture. However, at higher H{sub 2} concentration (10%) and flow velocity (Jet Exit Reynolds number > 200), formation of nanostructures diminishes and H{sub 2}-CH{sub 4} flames produce amorphous carbon and soot particles. The maximum yield of nanostructures occurs at 95-5% CH{sub 4}-H{sub 2} fuel compositions and 8.37E-07m{sup 3}/s (corresponding Jet Exit Reynolds number=200). Raman analyses of the pristine samples show the existence of distinctive multi-walled carbon nanotube (MWNT) D and G bands at 1321cm{sup -1} and 1595cm{sup -1}, respectively. Infrared absorption measurements of vibrational line characteristics of CNTs also reveal the presence of C-H bonds.

  16. Study of hepatotoxicity and oxidative stress in male Swiss-Webster mice exposed to functionalized multi-walled carbon nanotubes

    PubMed Central

    Patlolla, Anita K.; Berry, Ashley; Tchounwou, Paul B.

    2013-01-01

    Carbon nanotubes (CNTs), the most promising material with unique characteristics, find its application in different fields ranging from composite materials to medicine and from electronics to energy storage. However, little is known about the mechanisms behind the interaction of these particles with cells and their toxicity. The aim of this study was to assess the effects, after intraperitoneal injection, of functionalized multi walled carbon nanotubes (MWCNT) (carboxyl groups) on various hepatotoxicity and oxidative stress biomarkers (ROS, LHP, ALT, AST, ALP and morphology of liver) in the mouse model. The mice were dosed intraperitoneally at 0.25, 0.5 & 0.75 mg/kg/day for 5 days of purified/functionalized MWCNTs and two controls (negative; saline and positive; carbon black 0.75 mg/kg) as appropriate. Samples were collected 24 hours after the fifth day treatment following standard protocols. Exposure to carboxylated functionalized MWCNT; the body-weight gain of the mice decreased, induced reactive oxygen species (ROS), and enhanced the activities of serum amino-transferases (ALT/AST), alkaline phosphatases (ALP) and concentration of lipid hydro peroxide compared to control. Histopathology of exposed liver showed a statistically significant effect in the morphological alterations of the tissue compared to controls. The cellular findings reported here do suggest that purified carboxylated functionalized MWCNT has the potential to induce hepatotoxicity in Swiss-Webster mice through activation of the mechanisms of oxidative stress, which warrant in vivo animal exposure studies. However, more studies of functionalization in the in vivo toxicity of MWCNTs are required and parallel comparison is preferred. PMID:21725842