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Sample records for nanotube raman tags

  1. Raman spectra of filled carbon nanotubes

    International Nuclear Information System (INIS)

    Bose, S.M.; Behera, S.N.; Sarangi, S.N.; Entel, P.

    2004-01-01

    The Raman spectra of a metallic carbon nanotube filled with atoms or molecules have been investigated theoretically. It is found that there will be a three way splitting of the main Raman lines due to the interaction of the nanotube phonon with the collective excitations (plasmons) of the conduction electrons of the nanotube as well as its coupling with the phonon of the filling material. The positions and relative strengths of these Raman peaks depend on the strength of the electron-phonon interaction, phonon frequency of the filling atom and the strength of interaction of the nanotube phonon and the phonon of the filling atoms. Careful experimental studies of the Raman spectra of filled nanotubes should show these three peaks. It is also shown that in a semiconducting nanotube the Raman line will split into two and should be observed experimentally

  2. Raman spectroscopic characterization of multiwall carbon nanotubes and of composites

    Directory of Open Access Journals (Sweden)

    L. Bokobza

    2012-07-01

    Full Text Available In this work Raman spectroscopy was used for extensive characterization of multiwall carbon nanotube (MWNTs and of MWCNTs/rubber composites. We have measured the Raman spectra of bundled and dispersed multiwall carbon nanotubes. All the Raman bands of the carbon nanotubes are seen to shift to higher wavenumbers upon debundling on account of less intertube interactions. Effects of laser irradiation were also investigated. Strong effects are observed by changing the wavelength of the laser excitation. On the other hand, at a given excitation wavelength, changes on the Raman bands are observed by changing the laser power density due to sample heating during the measurement procedure.

  3. A Raman Study of Titanate Nanotubes | Liu | South African Journal ...

    African Journals Online (AJOL)

    The effect of the addition of NaOH or KOH on commercial Degussa Titania P25 was investigated using TEM, Raman and in situ Raman spectroscopy. Treatment of titania with conc. NaOH generated a tubular material corresponding to a sodium titanate. An in situ Raman study on the sodium titanate nanotubes as a function ...

  4. Combining portable Raman probes with nanotubes for theranostic applications.

    Science.gov (United States)

    Bhirde, Ashwinkumar A; Liu, Gang; Jin, Albert; Iglesias-Bartolome, Ramiro; Sousa, Alioscka A; Leapman, Richard D; Gutkind, J Silvio; Lee, Seulki; Chen, Xiaoyuan

    2011-01-01

    Recently portable Raman probes have emerged along with a variety of applications, including carbon nanotube (CNT) characterization. Aqueous dispersed CNTs have shown promise for biomedical applications such as drug/gene delivery vectors, photo-thermal therapy, and photoacoustic imaging. In this study we report the simultaneous detection and irradiation of carbon nanotubes in 2D monolayers of cancer cells and in 3D spheroids using a portable Raman probe. A portable handheld Raman instrument was utilized for dual purposes: as a CNT detector and as an irradiating laser source. Single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) were dispersed aqueously using a lipid-polymer (LP) coating, which formed highly stable dispersions both in buffer and cell media. The LP coated SWCNT and MWCNT aqueous dispersions were characterized by atomic force microscopy, transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy and Raman spectroscopy. The cellular uptake of the LP-dispersed SWCNTs and MWCNTs was observed using confocal microscopy, and fluorescein isothiocyanate (FITC)-nanotube conjugates were found to be internalized by ovarian cancer cells by using Z-stack fluorescence confocal imaging. Biocompatibility of SWCNTs and MWCNTs was assessed using a cell viability MTT assay, which showed that the nanotube dispersions did not hinder the proliferation of ovarian cancer cells at the dosage tested. Ovarian cancer cells treated with SWCNTs and MWCNTs were simultaneously detected and irradiated live in 2D layers of cancer cells and in 3D environments using the portable Raman probe. An apoptotic terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay carried out after laser irradiation confirmed that cell death occurred only in the presence of nanotube dispersions. We show for the first time that both SWCNTs and MWCNTs can be selectively irradiated and detected in cancer cells using a simple

  5. Observation of Electronic Raman Scattering in Metallic Carbon Nanotubes

    Czech Academy of Sciences Publication Activity Database

    Farhat, H.; Berciaud, S.; Kalbáč, Martin; Saito, R.; Heinz, T. F.; Dresselhaus, M. S.; Kong, J.

    2011-01-01

    Roč. 107, č. 15 (2011), s. 157401 ISSN 0031-9007 R&D Projects: GA MŠk ME09060 Institutional research plan: CEZ:AV0Z40400503 Keywords : spectroscopy * electronic Raman scattering * metallic carbon nanotubes Subject RIV: CG - Electrochemistry Impact factor: 7.370, year: 2011

  6. A Raman Study of Titanate Nanotubes

    African Journals Online (AJOL)

    NJD

    HRTEM data are also consistent with the synthesis of ... The nano titania produced by the electrochemical and template methods, gave amorphous titania while titania nanotubes produced by 'soft' chemical processes gave materials with good.

  7. Glioblastoma cells labeled by robust Raman tags for enhancing imaging contrast.

    Science.gov (United States)

    Huang, Li-Ching; Chang, Yung-Ching; Wu, Yi-Syuan; Sun, Wei-Lun; Liu, Chan-Chuan; Sze, Chun-I; Chen, Shiuan-Yeh

    2018-05-01

    Complete removal of a glioblastoma multiforme (GBM), a highly malignant brain tumor, is challenging due to its infiltrative characteristics. Therefore, utilizing imaging agents such as fluorophores to increase the contrast between GBM and normal cells can help neurosurgeons to locate residual cancer cells during image guided surgery. In this work, Raman tag based labeling and imaging for GBM cells in vitro is described and evaluated. The cell membrane of a GBM adsorbs a substantial amount of functionalized Raman tags through overexpression of the epidermal growth factor receptor (EGFR) and "broadcasts" stronger pre-defined Raman signals than normal cells. The average ratio between Raman signals from a GBM cell and autofluorescence from a normal cell can be up to 15. In addition, the intensity of these images is stable under laser illuminations without suffering from the severe photo-bleaching that usually occurs in fluorescent imaging. Our results show that labeling and imaging GBM cells via robust Raman tags is a viable alternative method to distinguish them from normal cells. This Raman tag based method can be used solely or integrated into an existing fluorescence system to improve the identification of infiltrative glial tumor cells around the boundary, which will further reduce GBM recurrence. In addition, it can also be applied/extended to other types of cancer to improve the effectiveness of image guided surgery.

  8. Calculation of the Raman intensity in graphene and carbon nanotubes

    Science.gov (United States)

    Moutinho, Marcus; Venezuela, Pedro

    2014-03-01

    Raman spectroscopy is one of the most important experimental techniques for characterization of carbon materials because it can give a lot of information about electronic and phonon structure in a non destructive way. We use a third-order quantum field model to obtain the theoretical Raman intensity for graphene and carbon nanotubes (CNT). The most important Raman peaks in graphitic materials comes from to the iLo and iTo phonon branches near to Γ and K points and, in this work, we focus our attention on some of these peaks, like the G, D and 2D bands, as a function of laser energy. The electronic and phonon dispersion used in our calculations reproduces the graphene ab initio results with GW corrections and the zone folding method is used to obtain the CNT ones. Our results show that the experimental G band Raman excitation profile for CNT can be reproduced if we use the proper electronic and phonon dispersions. We also show that the phonon dispersion may influence the shape of the graphene D band and the dispersive behavior of the 2D band for graphene and CNT. This work was supported by the Brazilian Nanocarbon Institute of Science and Technology (INCT/Nanocarbono), the Brazilian Network on Carbon Nanotube Research and the Brazilian agency CAPES

  9. Live-cell stimulated Raman scattering imaging of alkyne-tagged biomolecules.

    Science.gov (United States)

    Hong, Senlian; Chen, Tao; Zhu, Yuntao; Li, Ang; Huang, Yanyi; Chen, Xing

    2014-06-02

    Alkynes can be metabolically incorporated into biomolecules including nucleic acids, proteins, lipids, and glycans. In addition to the clickable chemical reactivity, alkynes possess a unique Raman scattering within the Raman-silent region of a cell. Coupling this spectroscopic signature with Raman microscopy yields a new imaging modality beyond fluorescence and label-free microscopies. The bioorthogonal Raman imaging of various biomolecules tagged with an alkyne by a state-of-the-art Raman imaging technique, stimulated Raman scattering (SRS) microscopy, is reported. This imaging method affords non-invasiveness, high sensitivity, and molecular specificity and therefore should find broad applications in live-cell imaging. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Alignment characterization of single-wall carbon nanotubes by Raman scattering

    International Nuclear Information System (INIS)

    Liu Pijun; Liu Liyue; Zhang Yafei

    2003-01-01

    A novel method for identifying the Raman modes of single-wall carbon nanotubes (SWNT) based on the symmetry of the vibration modes has been studied. The Raman intensity of each vibration mode varies with polarization direction, and the relationship can be expressed as analytical functions. This method avoids troublesome numerical calculation and easily gives clear relations between Raman intensity and polarization direction. In this way, one can distinguish each Raman-active mode of SWNT through the polarized Raman spectrum

  11. Tracking intracellular uptake and localisation of alkyne tagged fatty acids using Raman spectroscopy

    Science.gov (United States)

    Jamieson, Lauren E.; Greaves, Jennifer; McLellan, Jayde A.; Munro, Kevin R.; Tomkinson, Nicholas C. O.; Chamberlain, Luke H.; Faulds, Karen; Graham, Duncan

    2018-05-01

    Intracellular uptake, distribution and metabolism of lipids are tightly regulated characteristics in healthy cells. An analytical technique capable of understanding these characteristics with a high level of species specificity in a minimally invasive manner is highly desirable in order to understand better how these become disrupted during disease. In this study, the uptake and distribution of three different alkyne tagged fatty acids in single cells were monitored and compared, highlighting the ability of Raman spectroscopy combined with alkyne tags for better understanding of the fine details with regard to uptake, distribution and metabolism of very chemically specific lipid species. This indicates the promise of using Raman spectroscopy directly with alkyne tagged lipids for cellular studies as opposed to subsequently clicking of a fluorophore onto the alkyne for fluorescence imaging.

  12. Gap-enhanced Raman tags for high-contrast sentinel lymph node imaging.

    Science.gov (United States)

    Bao, Zhouzhou; Zhang, Yuqing; Tan, Ziyang; Yin, Xia; Di, Wen; Ye, Jian

    2018-05-01

    The sentinel lymph node (SLN) biopsy is gaining in popularity as a procedure to investigate the lymphatic metastasis of malignant tumors. The commonly used techniques to identify the SLNs in clinical practice are blue dyes-guided visualization, radioisotope-based detection and near-infrared fluorescence imaging. However, all these methods have not been found to perfectly fit the clinical criteria with issues such as short retention time in SLN, poor spatial resolution, autofluorescence, low photostability and high cost. In this study, we have reported a new type of nanoprobes, named, gap-enhanced Raman tags (GERTs) for the SLN Raman imaging. With the advantageous features including unique "fingerprint" Raman signal, strong Raman enhancement, high photostability, good biocompatibility and extra-long retention time, we have demonstrated that GERTs are greatly favorable for high-contrast and deep SLN Raman imaging, which meanwhile reveals the dynamic migration behavior of the probes entering the SLN. In addition, a quantitative volumetric Raman imaging (qVRI) data-processing method is employed to acquire a high-resolution 3-dimensional (3D) margin of SLN as well as the content variation of GERTs in the SLN. Moreover, SLN detection could be realized via a cost-effective commercial portable Raman scanner. Therefore, GERTs hold the great potential to be translated in clinical application for accurate and intraoperative location of the SLN. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. Defects in Individual Semiconducting Single Wall Carbon Nanotubes: Raman Spectroscopic and in Situ Raman Spectroelectrochemical Study

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Hsieh, Y. P.; Farhat, H.; Kavan, Ladislav; Hofmann, M.; Kong, J.; Dresselhaus, M. S.

    2010-01-01

    Roč. 10, č. 11 (2010), s. 4619-4626 ISSN 1530-6984 R&D Projects: GA ČR GC203/07/J067; GA AV ČR IAA400400804; GA AV ČR IAA400400911; GA AV ČR KAN200100801; GA MŠk ME09060 Institutional research plan: CEZ:AV0Z40400503 Keywords : single wall carbon nanotubes * Raman spectroscopy * defects Subject RIV: CG - Electrochemistry Impact factor: 12.186, year: 2010

  14. In vivo Raman flow cytometry for real-time detection of carbon nanotube kinetics in lymph, blood, and tissues

    Science.gov (United States)

    Biris, Alexandru S.; Galanzha, Ekaterina I.; Li, Zhongrui; Mahmood, Meena; Xu, Yang; Zharov, Vladimir P.

    2009-03-01

    Nanoparticles are intensively being explored as contrast agents for medical diagnostics and therapies using various optical methods. We present the first demonstration of the use of time-resolved Raman spectroscopy for in vivo real-time detection of circulating carbon nanotubes (CNTs) or cancer cells labeled with CNTs in the lymph, blood, and tissues of live animals with fast spectral acquisition times of down to few milliseconds. After intravenously administering CNTs in the tail vein of the rat, this technique provides the ability to detect the circulation of CNTs in the blood microvessels of the intact rat ear. The capability of Raman spectroscopy is also demonstrated to monitor, identify, and image the CNTs during their transportation by lymphatics in the rat ear and mesentery. The strong and specific Raman scattering properties of CNTs make it possible to detect in vitro and in vivo single cancer cells (HeLa) tagged with CNTs. In vivo Raman flow cytometry opens a new avenue for multiparameter analysis of circulating nanoparticles with strong Raman scattering properties and their pharmokinetics in blood and lymph systems. Moreover, this technology has the potential for molecular detection and identification of circulating tumor cells, and infections labeled with CNTs.

  15. High pressure Raman spectroscopy of single-walled carbon nanotubes: Effect of chemical environment on individual nanotubes and the nanotube bundle

    Science.gov (United States)

    Proctor, John E.; Halsall, Matthew P.; Ghandour, Ahmad; Dunstan, David J.

    2006-12-01

    The pressure-induced tangential mode Raman peak shifts for single-walled carbon nanotubes (SWNTs) have been studied using a variety of different solvents as hydrostatic pressure-transmitting media. The variation in the nanotube response to hydrostatic pressure with different pressure transmitting media is evidence that the common solvents used are able to penetrate the interstitial spaces in the nanotube bundle. With hexane, we find the surprising result that the individual nanotubes appear unaffected by hydrostatic pressures (i.e. a flat Raman response) up to 0.7 GPa. Qualitatively similar results have been obtained with butanol. Following the approach of Amer et al. [J. Chem. Phys. 121 (2004) 2752], we speculate that this is due to the inability of SWNTs to adsorb some solvents onto their surface at lower pressures. We also find that the role of cohesive energy density in the solvent nanotube interaction is more complex than previously thought.

  16. Double-wall carbon nanotubes doped with different Br2 doping levels: a resonance Raman study.

    Science.gov (United States)

    do Nascimento, Gustavo M; Hou, Taige; Kim, Yoong Ahm; Muramatsu, Hiroyuki; Hayashi, Takuya; Endo, Morinobu; Akuzawa, Noboru; Dresselhaus, Mildred S

    2008-12-01

    This report focuses on the effects of different Br2 doping levels on the radial breathing modes of "double-wall carbon nanotube (DWNT) buckypaper". The resonance Raman profile of the Br2 bands are shown for different DWNT configurations with different Br2 doping levels. Near the maximum intensity of the resonance Raman profile, mainly the Br2 molecules adsorbed on the DWNT surface contribute strongly to the observed omega(Br-Br) Raman signal.

  17. Characterization of bundled and individual triple-walled carbon nanotubes by resonant Raman spectroscopy.

    Science.gov (United States)

    Hirschmann, Thomas Ch; Araujo, Paulo T; Muramatsu, Hiroyuki; Zhang, Xu; Nielsch, Kornelius; Kim, Yoong Ahm; Dresselhaus, Mildred S

    2013-03-26

    The optical characterization of bundled and individual triple-walled carbon nanotubes was studied for the first time in detail by using resonant Raman spectroscopy. In our approach, the outer tube of a triple-walled carbon nanotube system protects the two inner tubes (or equivalently the inner double-walled carbon nanotube) from external environment interactions making them a partially isolated system. Following the spectral changes and line-widths of the radial breathing modes and G-band by performing laser energy dependent Raman spectroscopy, it is possible to extract important information as regards to the electronic and vibrational properties, tube diameters, wall-to-wall distances, radial breathing mode, and G-band resonance evolutions as well as high-curvature intertube interactions in isolated double- and triple-walled carbon nanotube systems.

  18. Chemical vapour deposition growth and Raman characterization of graphene layers and carbon nanotubes

    Science.gov (United States)

    Lai, Y.-C.; Rafailov, P. M.; Vlaikova, E.; Marinova, V.; Lin, S. H.; Yu, P.; Yu, S.-C.; Chi, G. C.; Dimitrov, D.; Sveshtarov, P.; Mehandjiev, V.; Gospodinov, M. M.

    2016-02-01

    Single-layer graphene films were grown by chemical vapour deposition (CVD) on Cu foil. The CVD process was complemented by plasma enhancement to grow also vertically aligned multiwalled carbon nanotubes using Ni nanoparticles as catalyst. The obtained samples were characterized by Raman spectroscopy analysis. Nature of defects in the samples and optimal growth conditions leading to achieve high quality of graphene and carbon nanotubes are discussed.

  19. Effects of ion beam heating on Raman spectra of single-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Hulman, Martin; Skakalova, Viera; Krasheninnikov, A. V.; Roth, S.

    2009-01-01

    Free standing films of single-wall carbon nanotubes were irradiated with energetic N + and C 4+ ions. The observed changes in the Raman line shape of the radial breathing mode and the G band of the C 4+ irradiated samples were similar to those found for a thermally annealed sample. We ascribe these changes to thermal desorption of volatile dopants from the initially doped nanotubes. A simple geometry of the experiment allows us to estimate the temperature rise by one-dimensional heat conductance equation. The calculation indicates that irradiation-mediated increase in temperature may account for the observed Raman spectra changes

  20. An in situ Raman spectroscopy study of stress transfer between carbon nanotubes and polymer

    International Nuclear Information System (INIS)

    Mu Minfang; Winey, Karen I; Osswald, Sebastian; Gogotsi, Yury

    2009-01-01

    The transfer mechanism of applied stress in single-wall carbon nanotube (SWCNT)/poly(methyl methacrylate) (PMMA) nanocomposites was investigated using in situ Raman spectroscopy on composite fibers. These SWCNT/PMMA nanocomposite fibers have no specific SWCNT-polymer interactions and the high degree of nanotube alignment minimizes the contributions from nanotube-nanotube interactions. Although tensile testing found significantly improved overall mechanical properties of the fibers, effective stress transfer to SWCNTs is limited to a small strain regime (ε<0.2%). At higher strains, the stress on the SWCNTs decreases due to the slippage at the nanotube-polymer interface. Slippage was also evident in scanning electron micrographs of fracture surfaces produced by tensile testing of the composite fibers. Above ε = 0.2%, the strain-induced slippage was accompanied by irreversible responses in stress and Raman peak shifts. This paper shows that efficient stress transfer to nanotubes as monitored by Raman spectroscopy is crucial to improving the mechanical properties of polymer nanocomposites and to detecting internal damage in nanocomposites.

  1. Synthesis of Au Nanostars and Their Application as Surface Enhanced Raman Scattering-Activity Tags Inside Living Cells.

    Science.gov (United States)

    Cao, Xiaowei; Shi, Chaowen; Lu, Wenbo; Zhao, Hang; Wang, Man; Tong, Wei; Dong, Jian; Han, Xiaodong; Qian, Weiping

    2015-07-01

    This work presents the synthesis and characterization of Au nanostars (AuNSs) and demonstrates their application as surface enhanced Raman scattering (SERS)-activity tags for cellular imaging and sensing. Nile blue A (NBA) and bovine serum albumin (BSA) were used as Raman reporter molecules and capping materials, respectively. The SERS-activity tags were tested on human lung adenocarcinoma cell (A549) and alveolar type II cell (AT II) and found to present a low level of cytotoxicity and high chemical stability. These SERS-activity tags not only can be applied in multiplexed cellular imaging, including dark field imaging, transmission electron microscopy (TEM) and SERS imaging, but also can be used for cellular sensing. The SERS spectra clearly identified cellular important components such as proteins, nucleic acids, lipids, and carbohydrates. This study also shows that endocytosis is the main channel of tags internalized in cells. The AuNSs exhibiting strong surface enhanced Raman effects are utilized in the design of an efficient, stable SERS-activity tag for intracellular applications.

  2. Structure in nascent carbon nanotubes revealed by spatially resolved Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Landois, Périne [CEA, IRAMIS, SPAM, Laboratoire Francis Perrin (CNRS URA 2453), 91191 Gif-sur-Yvette (France); Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris Sud 11, 91405 Orsay (France); Pinault, Mathieu [CEA, IRAMIS, SPAM, Laboratoire Francis Perrin (CNRS URA 2453), 91191 Gif-sur-Yvette (France); Huard, Mickaël [Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris Sud 11, 91405 Orsay (France); Reita, Valérie [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Rouzière, Stéphan; Launois, Pascale [Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris Sud 11, 91405 Orsay (France); Mayne-L' Hermite, Martine [CEA, IRAMIS, SPAM, Laboratoire Francis Perrin (CNRS URA 2453), 91191 Gif-sur-Yvette (France); Bendiab, Nedjma, E-mail: nedjma.bendiab@grenoble.cnrs.fr [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France)

    2014-10-01

    The understanding of carbon nanotube (CNT) growth is crucial for the control of their production. In particular, the identification of structural changes of carbon possibly occurring near the catalyst particle in the very early stages of their formation is of high interest. In this study, samples of nascent CNT obtained during nucleation step and samples of vertically aligned CNT obtained during growth step are analysed by combined spatially resolved Raman spectroscopy and X-ray diffraction measurements. Spatially resolved Raman spectroscopy reveals that iron-based phases and carbon phases are co-localized at the same position, and indicates that sp{sup 2} carbon nucleates preferentially on iron-based particles during this nucleation step. Depth scan Raman spectroscopy analysis, performed on nascent CNT, highlights that carbon structural organisation is significantly changing from defective graphene layers surrounding the iron-based particles at their base up to multi-walled nanotube structures in the upper part of iron-based particles. - Highlights: • Spatial co-localization of iron and carbon structures in nascent carbon nanotubes • Imaging local carbon structure changes along catalyst particles by Raman spectroscopy. • In nascent nanotubes, significant structural changes occur along catalyst particle.

  3. Diamond/carbon nanotube composites: Raman, FTIR and XPS spectroscopic studies

    Czech Academy of Sciences Publication Activity Database

    Varga, Marián; Ižák, Tibor; Vretenár, V.; Kozak, Halyna; Holovský, Jakub; Artemenko, Anna; Hulman, M.; Skákalová, V.; Lee, D. S.; Kromka, Alexander

    2016-01-01

    Roč. 111, Jan (2016), s. 54-61 ISSN 0008-6223 R&D Projects: GA ČR GC15-22102J; GA MŠk(CZ) 7AMB14SK037 Institutional support: RVO:68378271 Keywords : diamond * carbon nanotubes * spectroscopy * Raman * FTIR * XPS Subject RIV: JI - Composite Materials Impact factor: 6.337, year: 2016

  4. RGD-tagged helical rosette nanotubes aggravate acute lipopolysaccharide-induced lung inflammation

    Directory of Open Access Journals (Sweden)

    Suri SS

    2011-12-01

    Full Text Available Sarabjeet Singh Suri1, Steven Mills1, Gurpreet Kaur Aulakh1, Felaniaina Rakotondradany2, Hicham Fenniri2, Baljit Singh11Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon; 2National Institute for Nanotechnology and Department of Chemistry, Edmonton, CanadaAbstract: Rosette nanotubes (RNT are a novel class of self-assembled biocompatible nanotubes that offer a built-in strategy for engineering structure and function through covalent tagging of synthetic self-assembling modules (G∧C motif. In this report, the G∧C motif was tagged with peptide Arg-Gly-Asp-Ser-Lys (RGDSK-G∧C and amino acid Lys (K-G∧C which, upon co-assembly, generate RNTs featuring RGDSK and K on their surface in predefined molar ratios. These hybrid RNTs, referred to as Kx/RGDSKy-RNT, where x and y refer to the molar ratios of K-G∧C and RGDSK–G∧C, were designed to target neutrophil integrins. A mouse model was used to investigate the effects of intravenous Kx/RGDSKy-RNT on acute lipopolysaccharide (LPS-induced lung inflammation. Healthy male C57BL/6 mice were treated intranasally with Escherichia coli LPS 80 µg and/or intravenously with K90/RGDSK10-RNT. Here we provide the first evidence that intravenous administration of K90/RGDSK10-RNT aggravates the proinflammatory effect of LPS in the mouse. LPS and K90/RGDSK10-RNT treatment groups showed significantly increased infiltration of polymorphonuclear cells in bronchoalveolar lavage fluid at all time points compared with the saline control. The combined effect of LPS and K90/RGDSK10-RNT was more pronounced than LPS alone, as shown by a significant increase in the expression of interleukin-1ß, MCP-1, MIP-1, and KC-1 in the bronchoalveolar lavage fluid and myeloperoxidase activity in the lung tissues. We conclude that K90/RGDSK10-RNT promotes acute lung inflammation, and when used along with LPS, leads to exaggerated immune response in the lung.Keywords: RGD peptide, helical rosette

  5. Origin of enhancement in Raman scattering from Ag-dressed carbon-nanotube antennas : experiment and modelling

    NARCIS (Netherlands)

    Raziman, T.V.; Duenas, J.A.; Milne, W.I.; Martin, O.J.F.; Dawson, P.

    2018-01-01

    The D- and G-band Raman signals from random arrays of vertically aligned, multi-walled carbon nanotubes are significantly enhanced (up to ∼14×) while the signal from the underlying Si substrate is simultaneously attenuated (up to ∼6×) when the nanotubes are dressed, either capped or coated, with Ag.

  6. In situ Raman spectroscopy for growth monitoring of vertically aligned multiwall carbon nanotubes in plasma reactor

    Energy Technology Data Exchange (ETDEWEB)

    Labbaye, T.; Gaillard, M.; Lecas, T.; Kovacevic, E.; Boulmer-Leborgne, Ch.; Guimbretière, G. [GREMI, Université-CNRS, BP6744, 45067 Orléans Cedex 2 (France); Canizarès, A.; Raimboux, N.; Simon, P.; Ammar, M. R., E-mail: mohamed-ramzi.ammar@cnrs-orleans.fr [CNRS, CEMHTI UPR3079, Univ. Orléans, F-45071 Orléans Cedex 2 (France); Strunskus, T. [Institute of Material Science, Chritian-Albrechts-University of Kiel, D-24143 Kiel (Germany)

    2014-11-24

    Portable and highly sensitive Raman setup was associated with a plasma-enhanced chemical vapor deposition reactor enabling in situ growth monitoring of multi-wall carbon nanotubes despite the combination of huge working distance, high growth speed and process temperature and reactive plasma condition. Near Edge X-ray absorption fine structure spectroscopy was used for ex situ sample analysis as a complementary method to in situ Raman spectroscopy. The results confirmed the fact that the “alternating” method developed here can accurately be used for in situ Raman monitoring under reactive plasma condition. The original analytic tool can be of great importance to monitor the characteristics of these nanostructured materials and readily define the ultimate conditions for targeted results.

  7. Electrical and Raman spectroscopic studies of vertically aligned multi-walled carbon nanotubes.

    Science.gov (United States)

    Mathur, Ashish; Tweedie, Mark; Roy, Susanta Sinha; Maguire, P D; McLaughlin, James A

    2009-07-01

    Microwave plasma enhanced chemical vapour deposition (MPECVD) was used for the production of carbon nanotubes. Vertically aligned multi-walled carbon nanotubes (MWCNTs) were grown on silicon substrates coated with cobalt thin films of thickness ranging from 0.5 nm to 3 nm. Prior to the nanotube growth the catalyst were treated with N2 plasma for 5-10 minutes that break the films into small nanoparticles which favour the growth of nanotubes. The CNTs were grown at a substrate temperature of 700 degrees C for 5, 10 and 15 minutes. The height of the CNT films ranging from 10 microm-30 microm indicating that the initial growth rate of the CNTs are very high at a rate of approximately 100 nm/sec. Electrical resistivity of the above samples was evaluated from I-V measurements. The activation energy (E(a)) was also calculated from the temperature dependent studies and it was found that the E(a) lies in the range of 15-35 meV. Raman spectroscopy was used to identify the quality of the nanotubes.

  8. Charge transfer in carbon nanotube actuators investigated using in situ Raman spectroscopy

    International Nuclear Information System (INIS)

    Gupta, S.; Hughes, M.; Windle, A.H.; Robertson, J.

    2004-01-01

    Charge transfer dynamics on the surface of single-wall carbon nanotube sheets is investigated using in situ Raman spectroscopy in order to understand the actuation mechanism of an electrochemical actuator and to determine associated parameters. We built an actuator from single-wall carbon nanotube mat and studied its actuation in several alkali metal (Li, Na, and K) and alkaline earth (Ca) halide and sulfate solutions in order to clarify the role of counterion as mobile ions in the film. The variation of bonding with applied potential was monitored using in situ Raman spectroscopy. This is because Raman can detect changes in C-C bond length: the radial breathing mode at ∼190 cm-1 varies inversely with the nanotube diameter, and the G band at ∼1590 cm-1 varies with the axial bond length. In addition, the intensities of both the modes vary with the emptying/depleting or filling of the bonding and antibonding states due to electrochemical charge injection. We discussed the variation of peak height and wave numbers of these modes providing valuable information concerning electrochemical charge injection on the carbon nanotube mat surface. We found in-plane microscopic compressive strain (∼-0.25%) and the equivalent charge transfer per carbon atom (f c ∼-0.005) as an upper bound for the actuators studied hereby. It is demonstrated that though the present analysis does comply with the proposition for the actuation principle made earlier, the quantitative estimates are significantly lower if compared with those of reported values. Furthermore, the extent of variation, i.e., coupled electro-chemo-mechanical response of single-wall carbon nanotubes (SWNT) mat depended upon the type of counterion used (Group I versus Group II). The cyclic voltammetry and ac electrochemical impedance spectroscopy results were described briefly, which help to demonstrate well-developed capacitive behavior of SWNT mat and to estimate the specific capacitances as well. Summarizing, the

  9. Magnetic multiwalled carbon nanotubes as nanocarrier tags for sensitive determination of fetuin in saliva.

    Science.gov (United States)

    Sánchez-Tirado, Esther; González-Cortés, Araceli; Yáñez-Sedeño, Paloma; Pingarrón, José M

    2018-08-15

    This paper reports the development and performance of an electrochemical immunosensor using magnetic multiwalled carbon nanotubes (m-MWCNTs) as nanocarrier tags for the determination of human fetuin A (HFA), a relevant biomarker of obesity, insulin resistance, and type-2 diabetes as well as for pancreatic and liver cancers and inflammatory processes. Screen-printed carbon electrodes were grafted with p-aminobezoic acid and streptavidin was covalently immobilized on the electrode surface. A biotinylated capture antibody was immobilized through streptavidin-biotin interaction and a sandwich assay configuration was implemented using m-MWCNTs conjugated with HRP and anti-HFA antibodies as the detection label. The determination of HFA was accomplished by measuring the current produced by the electrochemical reduction of benzoquinone at -200 mV upon addition of H 2 O 2 as HRP substrate. The prepared m-MWCNTs were characterized by SEM, TEM, XRD and EDS. All the steps involved in the immunosensor preparation were monitored by electrochemical impedance spectroscopy and cyclic voltammetry. A linear calibration plot for HFA was found between 20 and 2000 pg/mL with a LOD value of 16 pg/mL. This performance is notably better than that reported for an ELISA kit and a chronoimpedimetric immunosensor. The favorable contribution of m-MWCNTs in comparison with MWCNTs without incorporated magnetic particles to this excellent analytical performance is also highlighted. The immunosensor selectivity against other proteins and potentially interfering compounds was excellent. In addition, the usefulness of the immunosensor was demonstrated by the analysis of HFA in saliva with minimal sample treatment. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Purity and Defect Characterization of Single-Wall Carbon Nanotubes Using Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Yasumitsu Miyata

    2011-01-01

    Full Text Available We investigated the purity and defects of single-wall carbon nanotubes (SWCNTs produced by various synthetic methods including chemical vapor deposition, arc discharge, and laser ablation. The SWCNT samples were characterized using scanning electron microscopy (SEM, thermogravimetric analysis (TGA, and Raman spectroscopy. Quantitative analysis of SEM images suggested that the G-band Raman intensity serves as an index for the purity. By contrast, the intensity ratio of G-band to D-band (G/D ratio reflects both the purity and the defect density of SWCNTs. The combination of G-band intensity and G/D ratio is useful for a quick, nondestructive evaluation of the purity and defect density of a SWCNT sample.

  11. Carbon nanotubes doped with trivalent elements by using back - scattering Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    S. A. Babanejad

    2008-12-01

    Full Text Available  In this paper by using DC arc discharge method and acetylene gas, as the carbon source, and nitrogen, as the carrier gas, canrbon nanotubes, CNTs, doped with trivalent element boron, B, have been produced. The deposited CNTs on the cathod electrod, which have structural doped properties to boron element, have been collected and after purification have been investigated by back-scattering Raman spectroscopy. The results reveal that the high frequency G mode component in CNTs doped with electron acceptor element, B, shift to higher wavenumbers. The low frequency G mode component which can appear at approximately 1540–1570 cm-1 wavenumber region, called BWF mode, is a sign of metallic CNT. In the synthesized doped CNTs due to the presence of boron dopant, D mode has sharp peaks and has relatively high intensity in the Raman spectra .

  12. Raman spectroscopy study of the doping effect of the encapsulated terbium halogenides on single-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Kharlamova, M.V.; Kramberger, C.; Mittelberger, A. [University of Vienna, Faculty of Physics, Vienna (Austria)

    2017-04-15

    In the present work, the doping effect of terbium chloride, terbium bromide, and terbium iodide on single-walled carbon nanotubes (SWCNTs) was compared by Raman spectroscopy. A precise investigation of the doping-induced alterations of the Raman modes of the filled SWCNTs was conducted. The shifts of the components of the Raman modes and modification of their profiles allowed concluding that the inserted terbium halogenides have acceptor doping effect on the SWCNTs, and the doping efficiency increases in the line with terbium iodide, terbium bromide, and terbium chloride. (orig.)

  13. Fermi energy dependence of the G-band resonance Raman spectra of single-wall carbon nanotubes

    Czech Academy of Sciences Publication Activity Database

    Park, J. S.; Sasaki, K.; Saito, R.; Izumida, W.; Kalbáč, Martin; Farhat, H.; Dresselhaus, G.; Dresselhaus, M. S.

    2009-01-01

    Roč. 80, č. 8 (2009), 081402-1-081402-4 ISSN 1098-0121 R&D Projects: GA MŠk LC510; GA MŠk ME09060 Institutional research plan: CEZ:AV0Z40400503 Keywords : Fermi energy dependence * Raman spectroscopy * single waled carbon nanotubes Subject RIV: CG - Electrochemistry Impact factor: 3.475, year: 2009

  14. Electrochemical Tuning of Electronic Structure of Single-Walled Carbon Nanotubes: In-situ Raman and VIS-NIR Study

    Czech Academy of Sciences Publication Activity Database

    Kavan, Ladislav; Rapta, P.; Dunsch, L.; Bronikowski, M. J.; Willis, P.; Smalley, R. E.

    2001-01-01

    Roč. 105, č. 44 (2001), s. 10764-10771 ISSN 1089-5647 R&D Projects: GA ČR GA203/99/1015 Institutional research plan: CEZ:AV0Z4040901 Keywords : carbon nanotubes * Raman spectroscopy * spectroelectrochemistry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.379, year: 2001

  15. Thermal transport of carbon nanotubes and graphene under optical and electrical heating measured by Raman spectroscopy

    Science.gov (United States)

    Hsu, I.-Kai

    This thesis presents systematic studies of thermal transport in individual single walled carbon nanotubes (SWCNTs) and graphene by optical and electrical approaches using Raman spectroscopy. In the work presented from Chapter 2 to Chapter 6, individual suspended CNTs are preferentially measured in order to explore their intrinsic thermal properties. Moreover, the Raman thermometry is developed to detect the temperature of the carbon nanotube (CNT). A parabolic temperature profile is observed in the suspended region of the CNT while a heating laser scans across it, providing a direct evidence of diffusive thermal transport in an individual suspended CNT. Based on the curvature of the temperature profile, we can solve for the ratio of thermal contact resistance to the thermal resistance of the CNT, which spans the range from 0.02 to 17. The influence of thermal contact resistance on the thermal transport in an individual suspended CNT is also studied. The Raman thermometry is carried out in the center of a CNT, while its contact length is successively shortened by an atomic force microscope (AFM) tip cutting technique. By investigating the dependence of the CNT temperature on its thermal contact length, the temperature of a CNT is found to increase dramatically as the contact length is made shorter. This work reveals the importance of manipulating the CNT thermal contact length when adopting CNT as a thermal management material. In using a focused laser to induce heating in a suspended CNT, one open question that remains unanswered is how many of the incident photons are absorbed by the CNT of interest. To address this question, micro-fabricated platinum thermometers, together with micro-Raman spectroscopy are used to quantify the optical absorption of an individual CNT. The absorbed power in the CNT is equal to the power detected by two thermometers at the end of the CNT. Our result shows that the optical absorption lies in the range between 0.03 to 0.44%. In

  16. Empirical Equation Based Chirality (n, m Assignment of Semiconducting Single Wall Carbon Nanotubes from Resonant Raman Scattering Data

    Directory of Open Access Journals (Sweden)

    Md Shamsul Arefin

    2012-12-01

    Full Text Available This work presents a technique for the chirality (n, m assignment of semiconducting single wall carbon nanotubes by solving a set of empirical equations of the tight binding model parameters. The empirical equations of the nearest neighbor hopping parameters, relating the term (2n, m with the first and second optical transition energies of the semiconducting single wall carbon nanotubes, are also proposed. They provide almost the same level of accuracy for lower and higher diameter nanotubes. An algorithm is presented to determine the chiral index (n, m of any unknown semiconducting tube by solving these empirical equations using values of radial breathing mode frequency and the first or second optical transition energy from resonant Raman spectroscopy. In this paper, the chirality of 55 semiconducting nanotubes is assigned using the first and second optical transition energies. Unlike the existing methods of chirality assignment, this technique does not require graphical comparison or pattern recognition between existing experimental and theoretical Kataura plot.

  17. Empirical Equation Based Chirality (n, m) Assignment of Semiconducting Single Wall Carbon Nanotubes from Resonant Raman Scattering Data

    Science.gov (United States)

    Arefin, Md Shamsul

    2012-01-01

    This work presents a technique for the chirality (n, m) assignment of semiconducting single wall carbon nanotubes by solving a set of empirical equations of the tight binding model parameters. The empirical equations of the nearest neighbor hopping parameters, relating the term (2n− m) with the first and second optical transition energies of the semiconducting single wall carbon nanotubes, are also proposed. They provide almost the same level of accuracy for lower and higher diameter nanotubes. An algorithm is presented to determine the chiral index (n, m) of any unknown semiconducting tube by solving these empirical equations using values of radial breathing mode frequency and the first or second optical transition energy from resonant Raman spectroscopy. In this paper, the chirality of 55 semiconducting nanotubes is assigned using the first and second optical transition energies. Unlike the existing methods of chirality assignment, this technique does not require graphical comparison or pattern recognition between existing experimental and theoretical Kataura plot. PMID:28348319

  18. Macroscopic Ensembles of Aligned Carbon Nanotubes in Bubble Imprints Studied by Polarized Raman Microscopy

    Directory of Open Access Journals (Sweden)

    Shota Ushiba

    2014-01-01

    Full Text Available We study the alignment of single-wall carbon nanotubes (SWCNTs in bubble imprints through polarized Raman microscopy. A hemispherical bubble containing SWCNTs is pressed against a glass substrate, resulting in an imprint of the bubble membrane with a coffee ring on the substrate. We find that macroscopic ensembles of aligned SWCNTs are obtained in the imprints, in which there are three patterns of orientations: (i azimuthal alignment on the coffee ring, (ii radial alignment at the edge of the membrane, and (iii random orientation at the center of the membrane. We also find that the alignment of SWCNTs in the imprints can be manipulated by spinning bubbles. The orientation of SWCNTs on the coffee ring is directed radially, which is orthogonal to the case of unspun bubbles. This approach enables one to align SWCNTs in large quantities and in a short time, potentially opening up a wide range of CNT-based electronic and optical applications.

  19. Raman spectroscopic investigations of swift heavy ion irradiation effects in single-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Olejniczak, A.; Skuratov, V.A.; Lukaszewicz, J.P.

    2013-01-01

    In this study, we report the results on swift heavy ion irradiation effects in single-walled carbon nanotubes (SWNTs). Buckypapers, prepared of CVD grown, SWNTs were irradiated at room temperature with 167 MeV Xe ions to fluences in the range of 6×10 11 - 6.5×10 13 cm -2 and investigated using Raman spectroscopy. We observed a rich set of features in the intermediate frequency mode region. Some of them, being defect-induced, resembled fairly well the phonon density of states (DOS) of nanocrystalline glassy carbon. Analysis of the RBM modes has shown that the broader metallic tubes are characterized by higher radiation stability than thinner semiconducting ones. (authors)

  20. Spontaneous confocal Raman microscopy--a tool to study the uptake of nanoparticles and carbon nanotubes into cells

    Science.gov (United States)

    Romero, Gabriela; Rojas, Elena; Estrela-Lopis, Irina; Donath, Edwin; Moya, Sergio Enrique

    2011-06-01

    Confocal Raman microscopy as a label-free technique was applied to study the uptake and internalization of poly(lactide- co-glycolide) (PLGA) nanoparticles (NPs) and carbon nanotubes (CNTs) into hepatocarcinoma human HepG2 cells. Spontaneous confocal Raman spectra was recorded from the cells exposed to oxidized CNTs and to PLGA NPs. The Raman spectra showed bands arising from the cellular environment: lipids, proteins, nucleic acids, as well as bands characteristic for either PLGA NPs or CNTs. The simultaneous generation of Raman bands from the cell and nanomaterials from the same spot proves internalization, and also indicates the cellular region, where the nanomaterial is located. For PLGA NPs, it was found that they preferentially co-localized with lipid bodies, while the oxidized CNTs are located in the cytoplasm.

  1. Observation of localized strains on vertically grown single-walled carbon nanotube forests via polarized Raman spectroscopy

    International Nuclear Information System (INIS)

    Park, June; Seong, Maeng-Je; Heo, Kwang; Hong, Seunghun; Min, Yo-Sep

    2014-01-01

    Vertically grown single-walled carbon nanotube (V-SWCNT) forests, synthesized by water-assisted plasma-enhanced chemical vapor deposition, were studied using polarized micro-Raman spectroscopy. Among three different sections (root, center and end) along the vertical growth direction, the degree of V-SWCNT alignment was highest in the center section. Raman frequency red-shifts up to 7 and 13 cm −1 , for RBM and G-band, respectively, were observed in the center section, with respect to the Raman frequencies measured in the root and the end sections. Raman frequency downshift and concurrent linewidth broadening of the G-band, revealing a localized strain, were also observed in the center section. The existence of a localized strain in the center section of the V-SWCNT was further confirmed by observing a strong polarization anisotropy of up to 8 cm −1 in the G-band Raman frequency for different polarized Raman scattering configurations at the same probed spot. (paper)

  2. New Raman-peak at 1850 cm(-1) observed in multiwalled carbon nanotubes produced by hydrogen arc discharge.

    Science.gov (United States)

    Chen, B; Kadowaki, Y; Inoue, S; Ohkohchi, M; Zhao, X; Ando, Y

    2010-06-01

    The new peak (near 1850 cm(-1)) assigned to carbon linear chain included in the centre of very thin innermost multiwalled carbon nanotubes (MWNTs) has been verified by Raman spectroscopy. These MWNTs were produced by dc arc discharge of pure graphite rods in pure hydrogen gas and existed in the cathode deposit. In this paper, we clarified that the new Raman-peaks could also be observed in the cathode deposit including MWNTs produced by hydrogen dc arc discharge using graphite electrode with added Y or La. By changing the quantity of addition (Y or La), dc arc current and pressure of ambient hydrogen gas, the optimum condition to get maximum intensity of the new Raman-peaks was obtained. For the case of 1 wt% La, dc 50 A, H2 pressure of 50 Torr was found to be optimum, and the intensity of new Raman-peak was even higher than the G-band peak. For the case of 1 wt% Y, dc 50 A, H2 pressure of 50 Torr was optimum, but the intensity of new Raman-peak was weaker than the G-band peak. Transmission electron microscopy observation revealed that the crystallinity of MWNTs produced with pure graphite rod was better than those produced with added Y or La.

  3. Asymmetric resonance Raman excitation profiles and violation of the Condon approximation in single-wall carbon nanotubes

    Science.gov (United States)

    Doorn, Stephen; Duque, Juan; Telg, Hagen; Chen, Hang; Swan, Anna; Haroz, Erik; Kono, Junichiro; Tu, Xiaomin; Zheng, Ming

    2012-02-01

    DNA wrapping-based ion exchange chromatography and density gradient ultracentrifugation provide nanotube samples highly enriched in single chiralities. We present resonance Raman excitation profiles for the G-band of several single chirality semiconducting and metallic species. The expected incoming and outgoing resonance peaks are observed in the profiles, but contrary to long-held assumptions, the outgoing resonance is always significantly weaker than the ingoing resonance peak. This strong asymmetry in the profiles arises from a violation of the Condon approximation [1]. Results will be discussed in the context of theoretical models that suggest significant coordinate dependence in the transition dipole (non-Condon effects). The generality of the behavior across semiconducting and metallic types, nanotube family, phonon mode, and Eii will be demonstrated. [4pt] [1] J. Duque et. al., ACS Nano, 5, 5233 (2011).

  4. Zinc oxide nanotubes decorated with silver nanoparticles as an ultrasensitive substrate for surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Gao, M.; Feng, B.; Sun, Y.; Xing, G.; Li, S.; Yang, J.; Yang, L.; Zhang, Y.; Liu, H.; Fan, H.; Sui, Y.; Zhang, Z.; Liu, S.; Song, H.

    2012-01-01

    We report on the fabrication of a highly aligned silver-decorated array of zinc oxide nanotubes for use in surface-enhanced Raman spectroscopy (SERS). The ZnO nanotube array was first prepared by chemical etching, and the silver nanoparticles (AgNPs) were then deposited on their surface by magnetron sputtering. Such ZnO/Ag hybrid structures are shown to act as SERS-active substrates with remarkable sensitivity. The enhancement factor can be as high as 10 5 when using 4-mercaptopyridine in solution as a SERS probe. The synergistic combination between SERS 'hot spots' and the formation of an interfacial electric field between the zinc oxide nanotubes and the AgNPs in our opinion contribute to the high sensitivity. The relative standard deviations of signal intensities for the major SERS peaks are <7 %. This demonstrates that the optimized ZnO/Ag hybrid represents an excellent SERS substrate that may be used in trace analysis and ultrasensitive molecular sensing. (author)

  5. Detoxification of gold nanorods by conjugation with thiolated poly(ethylene glycol) and their assessment as SERS-active carriers of Raman tags

    Energy Technology Data Exchange (ETDEWEB)

    Boca, Sanda C; Astilean, Simion, E-mail: sboca@phys.ubbcluj.ro, E-mail: sastil@phys.ubbcluj.ro [Nanobiophotonics Center, Institute for Interdisciplinary Research in Nanobioscience, Babes-Bolyai University, Treboniu Laurian Street 42, 400271 Cluj-Napoca (Romania)

    2010-06-11

    We present an effective, low cost protocol to reduce the toxicity of gold nanorods induced by the presence of cetyltrimethylammonium bromide (CTAB) on their lateral surface as a result of the synthesis process. Here, we use thiolated methoxy-poly(ethylene) glycol (mPEG-SH) polymer to displace most of the CTAB bilayer cap from the particle surface. The detoxification process, chemical and structural stability of as-prepared mPEG-SH-conjugated gold nanorods were characterized using a number of techniques including localized surface plasmon resonance (LSPR), transmission electron microscopy (TEM) and surface-enhanced Raman spectroscopy (SERS). In view of future applications as near-infrared (NIR) nanoheaters in localized photothermal therapy of cancer, we investigated the thermal behaviour of mPEG-SH-conjugated gold nanorods above room temperature. We found a critical temperature at around 40 deg. C at which the adsorbed polymer layer is susceptible to undergo conformational changes. Additionally, we believe that such plasmonic nanoprobes could act as SERS-active carriers of Raman tags for application in cellular imaging. In this sense we successfully tested them as effective SERS substrates at 785 nm laser line with p-aminothiophenol (pATP) as a tag molecule.

  6. Detoxification of gold nanorods by conjugation with thiolated poly(ethylene glycol) and their assessment as SERS-active carriers of Raman tags

    Science.gov (United States)

    Boca, Sanda C.; Astilean, Simion

    2010-06-01

    We present an effective, low cost protocol to reduce the toxicity of gold nanorods induced by the presence of cetyltrimethylammonium bromide (CTAB) on their lateral surface as a result of the synthesis process. Here, we use thiolated methoxy-poly(ethylene) glycol (mPEG-SH) polymer to displace most of the CTAB bilayer cap from the particle surface. The detoxification process, chemical and structural stability of as-prepared mPEG-SH-conjugated gold nanorods were characterized using a number of techniques including localized surface plasmon resonance (LSPR), transmission electron microscopy (TEM) and surface-enhanced Raman spectroscopy (SERS). In view of future applications as near-infrared (NIR) nanoheaters in localized photothermal therapy of cancer, we investigated the thermal behaviour of mPEG-SH-conjugated gold nanorods above room temperature. We found a critical temperature at around 40 °C at which the adsorbed polymer layer is susceptible to undergo conformational changes. Additionally, we believe that such plasmonic nanoprobes could act as SERS-active carriers of Raman tags for application in cellular imaging. In this sense we successfully tested them as effective SERS substrates at 785 nm laser line with p-aminothiophenol (pATP) as a tag molecule.

  7. Detoxification of gold nanorods by conjugation with thiolated poly(ethylene glycol) and their assessment as SERS-active carriers of Raman tags

    International Nuclear Information System (INIS)

    Boca, Sanda C; Astilean, Simion

    2010-01-01

    We present an effective, low cost protocol to reduce the toxicity of gold nanorods induced by the presence of cetyltrimethylammonium bromide (CTAB) on their lateral surface as a result of the synthesis process. Here, we use thiolated methoxy-poly(ethylene) glycol (mPEG-SH) polymer to displace most of the CTAB bilayer cap from the particle surface. The detoxification process, chemical and structural stability of as-prepared mPEG-SH-conjugated gold nanorods were characterized using a number of techniques including localized surface plasmon resonance (LSPR), transmission electron microscopy (TEM) and surface-enhanced Raman spectroscopy (SERS). In view of future applications as near-infrared (NIR) nanoheaters in localized photothermal therapy of cancer, we investigated the thermal behaviour of mPEG-SH-conjugated gold nanorods above room temperature. We found a critical temperature at around 40 deg. C at which the adsorbed polymer layer is susceptible to undergo conformational changes. Additionally, we believe that such plasmonic nanoprobes could act as SERS-active carriers of Raman tags for application in cellular imaging. In this sense we successfully tested them as effective SERS substrates at 785 nm laser line with p-aminothiophenol (pATP) as a tag molecule.

  8. Chirality, Metallicity, and Transition Dependent Asymmetries in Resonance Raman Excitation Profiles of Chirality-Enriched Carbon Nanotubes

    Science.gov (United States)

    Doorn, Stephen; Duque, Juan; Telg, Hagen; Haroz, Erik; Tu, Xiaomin; Zheng, Ming

    2014-03-01

    Access to carbon nanotube samples enriched in single chiralities allows the observation of new photophysical behaviors obscured or difficult to demonstrate in mixed-chirality ensembles. Recent examples include the observation of strongly asymmetric G-band excitation profiles resulting from non-Condon effects1 and the unambiguous demonstration of Raman interference effects.2 We present here our most recent results demonstrating the generality of the non-Condon behavior to include metallic species (specifically several armchair chiralities). Additionally, the Eii dependence in non-Condon behavior with excitations from E11 thru E44 for both RBM and G modes will be discussed. 1. J.G. Duque, et. al., ACS Nano, 5, 5233 (2011). 2. J.G. Duque, et. al., Phys. Rev. Lett. 108, 117404 (2012).

  9. Mapping the intracellular distribution of carbon nanotubes after targeted delivery to carcinoma cells using confocal Raman imaging as a label-free technique

    International Nuclear Information System (INIS)

    Lamprecht, C; Unterauer, B; Plochberger, B; Brameshuber, M; Hinterdorfer, P; Ebner, A; Gierlinger, N; Hild, S; Heister, E

    2012-01-01

    The uptake of carbon nanotubes (CNTs) by mammalian cells and their distribution within cells is being widely studied in recent years due to their increasing use for biomedical purposes. The two main imaging techniques used are confocal fluorescence microscopy and transmission electron microscopy (TEM). The former, however, requires labeling of the CNTs with fluorescent dyes, while the latter is a work-intensive technique that is unsuitable for in situ bio-imaging. Raman spectroscopy, on the other hand, presents a direct, straightforward and label-free alternative. Confocal Raman microscopy can be used to image the CNTs inside cells, exploiting the strong Raman signal connected to different vibrational modes of the nanotubes. In addition, cellular components, such as the endoplasmic reticulum and the nucleus, can be mapped. We first validate our method by showing that only when using the CNTs’ G band for intracellular mapping accurate results can be obtained, as mapping of the radial breathing mode (RBM) only shows a small fraction of CNTs. We then take a closer look at the exact localization of the nanotubes inside cells after folate receptor-mediated endocytosis and show that, after 8-10 h incubation, the majority of CNTs are localized around the nucleus. In summary, Raman imaging has enormous potential for imaging CNTs inside cells, which is yet to be fully realized. (paper)

  10. HR-TEM and FT-Raman dataset of the caffeine interacted Phe-Phe peptide nanotube for possible sensing applications.

    Science.gov (United States)

    Narayanan, A Lakshmi; Dhamodaran, M; Solomon, J Samu; Karthikeyan, B; Govindhan, R

    2018-02-01

    Sensing ability of caffeine interaction with Phe-Phe annotates (PNTs), is presented (Govindhan et al., 2017; Karthikeyan et al., 2014; Tavagnacco et al., 2013; Kennedy et al., 2011; Wang et al., 2017) [1-5] in this data set. Investigation of synthesized caffeine carrying peptide nanotubes are carried out by FT-Raman spectral analysis and high resolution transmission electron microscopy (HR-TEM). Particle size of the caffeine loaded PNTs is < 40 nm. The FT-Raman spectrum signals are enhanced in the region of 400-1700 cm -1 . These data are ideal tool for the applications like biosensing and drug delivery research (DDS).

  11. HR-TEM and FT-Raman dataset of the caffeine interacted Phe–Phe peptide nanotube for possible sensing applications

    OpenAIRE

    Narayanan, A. Lakshmi; Dhamodaran, M.; Solomon, J. Samu; Karthikeyan, B.; Govindhan, R.

    2017-01-01

    Sensing ability of caffeine interaction with Phe-Phe annotates (PNTs), is presented (Govindhan et al., 2017; Karthikeyan et al., 2014; Tavagnacco et al., 2013; Kennedy et al., 2011; Wang et al., 2017) [1–5] in this data set. Investigation of synthesized caffeine carrying peptide nanotubes are carried out by FT-Raman spectral analysis and high resolution transmission electron microscopy (HR-TEM). Particle size of the caffeine loaded PNTs is < 40 nm. The FT-Raman spectrum signals are enhanced i...

  12. An in situ Raman spectroelectrochemical study of the controlled doping of semiconducting single walled carbon nanotubes in a conducting polymer matrix

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Kavan, Ladislav; Dunsch, L.

    2009-01-01

    Roč. 159, 21-22 (2009), s. 2245-2248 ISSN 0379-6779 R&D Projects: GA AV ČR KJB400400601; GA AV ČR IAA400400804; GA AV ČR IAA400400911; GA ČR GC203/07/J067 Institutional research plan: CEZ:AV0Z40400503 Keywords : PEDOT/PSS * carbon nanotubes * nanocomposites * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 1.901, year: 2009

  13. Investigating the Catalytic Growth of Carbon Nanotubes with In Situ Raman Monitoring

    Science.gov (United States)

    2015-06-01

    thickness and leading to the formation of small particles (less than 5 nm) and (ii) surface dewetting prevailing for thick catalyst layers and leading to...large particles (5–20 nm, see AFM data in Fig. S1) with a higher degree of oxidation (i.e. Co3O4) by surface dewetting . Under weakly-reducing growth... dewetting . These bimodal size and chemi- cal distributions strongly impact the conditions required for activating nanotube growth: weakly-reducing

  14. Raman spectral features of single walled carbon nanotubes synthesized by laser vaporization

    CSIR Research Space (South Africa)

    Moodley, MK

    2006-07-05

    Full Text Available synthesized boxshadowdwnSemi-conductor tubes were favoured boxshadowdwnImproved crystallinity as indicated by narrower line- widths. Thank You Acknowledgements to the CSIR NLC for support on carbon nanotube research ... www.csir.co.za Experimental……..cont. Experimental parameters • two laser combined and vaporize a composite target • target in a tube furnace in continuous flow of Argon • temperature kept at 1000 OC • Ar flow of 200 sccm • Pressure at 375 Torr...

  15. HR-TEM and FT-Raman dataset of the caffeine interacted Phe–Phe peptide nanotube for possible sensing applications

    Directory of Open Access Journals (Sweden)

    A. Lakshmi Narayanan

    2018-02-01

    Full Text Available Sensing ability of caffeine interaction with Phe-Phe annotates (PNTs, is presented (Govindhan et al., 2017; Karthikeyan et al., 2014; Tavagnacco et al., 2013; Kennedy et al., 2011; Wang et al., 2017 [1–5] in this data set. Investigation of synthesized caffeine carrying peptide nanotubes are carried out by FT-Raman spectral analysis and high resolution transmission electron microscopy (HR-TEM. Particle size of the caffeine loaded PNTs is < 40 nm. The FT-Raman spectrum signals are enhanced in the region of 400–1700 cm−1. These data are ideal tool for the applications like biosensing and drug delivery research (DDS. Keywords: Caffeine, PNTs, Sensing, HR-TEM, FT-Raman data

  16. Preparation, characterization, Raman, and terahertz spectroscopy study on carbon nanotubes, graphene nano-sheets, and onion like carbon materials

    International Nuclear Information System (INIS)

    Abouelsayed, A.; Anis, Badawi; Hassaballa, Safwat; Khalil, Ahmed S.G.; Rashed, Usama M.; Eid, Kamal A.; Al-Ashkar, Emad; El hotaby, W.

    2017-01-01

    We present the optical properties of carbon nanotubes, graphene nanosheets, and onion like carbon (OLC) samples with different cages size in wide frequency range from 0.06 to 1650 THz. The samples were characterized by high resolution transmission electron microscope (HRTEM), Raman, and UV–Vis-IR-THz spectroscopy. The broad absorption bands centered at around 10, 3, 2.5, 1.5, and 1.8 THz for SWCNTs, MWCNTs, graphene nanosheets, large cages (OLC 1 ), and small cages (OLC 2 ) samples, respectively, are assigned to plasmon resonance due to the localization of free carriers in a finite length. For SWCNTs, both the plasmon band position and the Drude weight (D) are located at higher values as compared with MWCNTs, graphene nanosheets, and OLC sample, suggesting that the dimensionality of the system plays a major role regarding the carrier mobility of the graphene structure. The differences in the estimated values of D, the Fermi energy (E f ), and density of carriers (N) in case of OLC samples can be due to the variation in sizes of the cages and the variation of the defects in the structure of the outermost layers of cages, where each cages consist of multi-layers of graphene enclosed one into another. - Highlights: • Preparation and spectroscopic studies on carbonaceous materials were performed. • Drude-Lorentz model were used for fitting the optical conductivity spectra. • The plasmonic resonances have been observed in THz frequency range. • The charge density N has been effected by disordered of the grapheme structure. • The σ DC values is decreased in case of 2D carbonaceous materials.

  17. Preparation, characterization, Raman, and terahertz spectroscopy study on carbon nanotubes, graphene nano-sheets, and onion like carbon materials

    Energy Technology Data Exchange (ETDEWEB)

    Abouelsayed, A., E-mail: as.abouelsayed@gmail.com [Spectroscopy Department, Physics Division, National Research Centre, 33 El Bohouth St. (fromer El Tahrir St.), Dokki, P.O. 12622, Giza (Egypt); Anis, Badawi [Spectroscopy Department, Physics Division, National Research Centre, 33 El Bohouth St. (fromer El Tahrir St.), Dokki, P.O. 12622, Giza (Egypt); Hassaballa, Safwat [Physics Department, Faculty of Science, Al-Azhar University, Cairo 11884 (Egypt); Khalil, Ahmed S.G. [Center for Environmental and Smart Technology, Fayoum University, Fayoum (Egypt); Egypt Nanotechnology Center, Cairo University, Giza (Egypt); Arab Academy for Science, Technology and Maritime Transport, Smart Village Campus, Giza (Egypt); Rashed, Usama M. [Physics Department, Faculty of Science, Al-Azhar University, Cairo 11884 (Egypt); Eid, Kamal A.; Al-Ashkar, Emad; El hotaby, W. [Spectroscopy Department, Physics Division, National Research Centre, 33 El Bohouth St. (fromer El Tahrir St.), Dokki, P.O. 12622, Giza (Egypt)

    2017-03-01

    We present the optical properties of carbon nanotubes, graphene nanosheets, and onion like carbon (OLC) samples with different cages size in wide frequency range from 0.06 to 1650 THz. The samples were characterized by high resolution transmission electron microscope (HRTEM), Raman, and UV–Vis-IR-THz spectroscopy. The broad absorption bands centered at around 10, 3, 2.5, 1.5, and 1.8 THz for SWCNTs, MWCNTs, graphene nanosheets, large cages (OLC{sub 1}), and small cages (OLC{sub 2}) samples, respectively, are assigned to plasmon resonance due to the localization of free carriers in a finite length. For SWCNTs, both the plasmon band position and the Drude weight (D) are located at higher values as compared with MWCNTs, graphene nanosheets, and OLC sample, suggesting that the dimensionality of the system plays a major role regarding the carrier mobility of the graphene structure. The differences in the estimated values of D, the Fermi energy (E{sub f}), and density of carriers (N) in case of OLC samples can be due to the variation in sizes of the cages and the variation of the defects in the structure of the outermost layers of cages, where each cages consist of multi-layers of graphene enclosed one into another. - Highlights: • Preparation and spectroscopic studies on carbonaceous materials were performed. • Drude-Lorentz model were used for fitting the optical conductivity spectra. • The plasmonic resonances have been observed in THz frequency range. • The charge density N has been effected by disordered of the grapheme structure. • The σ{sub DC} values is decreased in case of 2D carbonaceous materials.

  18. Combined antenna and localized plasmon resonance in Raman scattering from random arrays of silver-coated, vertically aligned multiwalled carbon nanotubes.

    Science.gov (United States)

    Dawson, P; Duenas, J A; Boyle, M G; Doherty, M D; Bell, S E J; Kern, A M; Martin, O J F; Teh, A-S; Teo, K B K; Milne, W I

    2011-02-09

    The electric field enhancement associated with detailed structure within novel optical antenna nanostructures is modeled using the surface integral equation technique in the context of surface-enhanced Raman scattering (SERS). The antennae comprise random arrays of vertically aligned, multiwalled carbon nanotubes dressed with highly granular Ag. Different types of "hot-spot" underpinning the SERS are identified, but contrasting characteristics are revealed. Those at the outer edges of the Ag grains are antenna driven with field enhancement amplified in antenna antinodes while intergrain hotspots are largely independent of antenna activity. Hot-spots between the tops of antennae leaning towards each other also appear to benefit from antenna amplification.

  19. Billfish Tagging

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The SWFSC's constituent-based Billfish Tagging Program began in 1963 and since that time has provided conventional spaghetti type tags and tagging supplies to...

  20. Raman characterization of 0.4 nm single-walled carbon nanotubes formed in the channels of AlPO4-5 zeolite single crystals

    International Nuclear Information System (INIS)

    Ye, J T; Zhai, J P; Tang, Z K

    2007-01-01

    In this paper, we review our recent research on ultra-small single-walled carbon nanotubes (SWNTs). Using Raman scattering as a tool, we systematically studied the pyrolysis process of carbon precursors in the channels of AlPO 4 -5 zeolite single crystals, and studied the formation process of the ultra-small SWNTs in the channels. The thermal expansion behaviour and thermal stability of these ultra-small SWNTs, either confined in the AlPO 4 -5 channels or in a freestanding environment, were also studied as a function of temperature. The in situ Raman-scattering measurement under 1 x 10 -5 mbar showed that the (3, 3) and (4, 2) tubes were totally destroyed at a temperature of about 700 K, while the (5, 0) tube can survive to 790 K. The electronic states of the 0.4 nm SWNTs were modulated by means of lithium doping. The continuous electron charge transfer from lithium atoms to the tubes was traced using Raman scattering. With increasing doping level, the radial breathing modes of these tubes shifted to higher frequency because the vibration perpendicular to the tube axis was depressed, in contrast to the conventional softening and downshift of the tangential G-mode vibrations

  1. Tag questions Tag questions

    Directory of Open Access Journals (Sweden)

    David Brazil

    2008-04-01

    Full Text Available The so-called 'tag' structures of English have received a lot of attention in language teaching programmes, attention that is not hard to justify when one considers the problems and anxiety they can occasion for many foreign learners. Most teachers one speaks to seem fairly willing to agree, however, that traditional treatments of the topic leave much to be desired. It happens, also, that, when considered collectively, the tags and some related phenomena have a special heoretical interest. For they constitute a field in which it seems essential to bring together insights that derive from the study of several aspects of linguistic organisation, aspects which in some recent work have been held to need distinctive kinds of descriptive category to handle. Traditional treatments have found it necessary to recognise different syntactic types (e.g. 'same polarity' and 'reversed polarity' tags and ifferent intonational treatments ("falling'and 'rising' tag; while the way the communicative significance of the various permutations is described normally requires reference to the expectations they signal regarding the immediately following behaviour of the other party (in the common phrase, 'What kind of answer they expect'. This last consideration places the matter squarely in the arena of recent work on the analysis of interactive discourse. The so-called 'tag' structures of English have received a lot of attention in language teaching programmes, attention that is not hard to justify when one considers the problems and anxiety they can occasion for many foreign learners. Most teachers one speaks to seem fairly willing to agree, however, that traditional treatments of the topic leave much to be desired. It happens, also, that, when considered collectively, the tags and some related phenomena have a special heoretical interest. For they constitute a field in which it seems essential to bring together insights that derive from the study of several aspects

  2. Facile preparation of water dispersible polypyrrole nanotube-supported silver nanoparticles for hydrogen peroxide reduction and surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Peng Yingjing; Qiu Lihua; Pan Congtao; Wang Cancan; Shang Songmin; Yan Feng

    2012-01-01

    Water dispersible polypyrrole nanotube/silver nanoparticle hybrids (PPyNT-COOAgNP) were synthesized via a cation-exchange method. The approach involves the surface functionalization of PPyNTs with carboxylic acid groups (-COOH), and cation-exchange with silver ions (Ag + ) and followed by the reduction of metal ions. The morphology and optical properties of the produced PPyNT-COOAgNP nanohybrids were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectrometer, and UV–vis spectroscopy. The as-prepared PPyNT-COOAgNP nanohybrids exhibited well-defined response to the reduction of hydrogen peroxide, and as extremely suitable substrates for surface-enhanced Raman spectroscopy (SERS) with a high enhancement factor of 6.0 × 10 7 , and enabling the detection of 10 −12 M Rhodamine 6G solution.

  3. Sexithiophene Encapsulated in a Single-Walled Carbon Nanotube: An In Situ Raman Spectroelectrochemical Study of a Peapod Structure

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Kavan, Ladislav; Gorantla, S.; Gemming, T.; Dunsch, L.

    2010-01-01

    Roč. 16, č. 38 (2010), s. 11753-11759 ISSN 0947-6539 R&D Projects: GA ČR GC203/07/J067 Institutional research plan: CEZ:AV0Z40400503 Keywords : doping * electrochemistry * carbon nanotubes Subject RIV: CG - Electrochemistry Impact factor: 5.476, year: 2010

  4. Raman Spectroscopic Study of Carbon Nanotubes Prepared Using Fe/ZnO-Palm Olein-Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    Syazwan Afif Mohd Zobir

    2012-01-01

    Full Text Available Multiwalled carbon nanotubes (MWCNTs were synthesized using Fe/ZnO catalyst by a dual-furnace thermal chemical vapor deposition (CVD method at 800–1000°C using nitrogen gas with a constant flow rate of 150 sccm/min as a gas carrier. Palm olein (PO, ferrocene in the presence of 0.05 M zinc nitrate, and a p-type silicon wafer were used as carbon source, catalyst precursor, and sample target, respectively. D, G, and G′ bands were observed at 1336–1364, 1559–1680, and 2667–2682 cm-1, respectively. Carbon nanotubes (CNTs with the highest degree of crystallinity were obtained at around 8000°C, and the smallest diameter of about 2 nm was deposited on the silicon substrate at 1000°C.

  5. Micro-raman and tip-enhanced raman spectroscopy of carbon allotropes

    NARCIS (Netherlands)

    Hoffmann, G.G.; With, de G.; Loos, J.

    2008-01-01

    Raman spectroscopic data are obtained on various carbon allotropes like diamond, amorphous carbon, graphite, graphene and single wall carbon nanotubes by micro-Raman spectroscopy, tip-enhanced Raman spectroscopy and tip-enhanced Raman spectroscopy imaging, and the potentials of these techniques for

  6. Carbon nanotubes : from molecular to macroscopic sensors

    NARCIS (Netherlands)

    Wood, J.R.; Zhao, Qing; Frogley, M.D.; Meurs, E.R.; Prins, A.D.; Peijs, A.A.J.M.; Dunstan, D.J.; Wagner, H.D.

    2000-01-01

    The components that contribute to Raman spectral shifts of single-wall carbon nanotubes (SWNT’s) embedded in polymer systems have been identified. The temperature dependence of the Raman shift can be separated into the temperature dependence of the nanotubes, the cohesive energy density of the

  7. Yellowtail Tagging Data (MRDBS)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Yellowtail Flounder Tagging Program began in 2003 and works with commercial fishermen to tag and release yellowtaiI flounder with pink and yellow disc tags or...

  8. Towards quantification of the ratio of the single and double wall carbon nanotubes in their mixtures: An in situ Raman spectroelectrochemical study

    Czech Academy of Sciences Publication Activity Database

    Komínková, Zuzana; Valeš, Václav; Hersam, M. C.; Kalbáč, Martin

    2014-01-01

    Roč. 78, NOV 2014 (2014), s. 366-373 ISSN 0008-6223 R&D Projects: GA MŠk LL1301; GA ČR GAP204/10/1677 Institutional support: RVO:61388955 Keywords : spectroscopy * spectroelectrochemistry * nanotubes Subject RIV: CG - Electrochemistry Impact factor: 6.196, year: 2014

  9. Calculation of Raman parameters of real-size zigzag (n, 0) single-walled carbon nanotubes using finite-size models

    Czech Academy of Sciences Publication Activity Database

    Kupka, T.; Stachów, M.; Stobinski, L.; Kaminský, Jakub

    2016-01-01

    Roč. 18, č. 36 (2016), s. 25058-25069 ISSN 1463-9076 R&D Projects: GA ČR(CZ) GA16-00270S Institutional support: RVO:61388963 Keywords : Raman spectroscopy * SWCNT * DFT Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.123, year: 2016

  10. An Anomalous Enhancement of the A(g)(2) Mode in the Resonance Raman Spectra of C-60 Embedded in Single-Walled Carbon Nanotubes during Anodic Charging

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Zólyomi, V.; Rusznyák, A.; Koltai, J.; Kürti, J.; Kavan, Ladislav

    2010-01-01

    Roč. 114, č. 6 (2010), 2505-2511 ISSN 1932-7447 R&D Projects: GA AV ČR IAA400400804; GA AV ČR IAA400400911; GA AV ČR KAN200100801; GA ČR GC203/07/J067 Institutional research plan: CEZ:AV0Z40400503 Keywords : spectroelectrochemie * Raman spectra * SWNT Subject RIV: CG - Electrochemistry Impact factor: 4.520, year: 2010

  11. Influence of the Resonant Electronic Transition on the Intensity of the Raman Radial Breathing Mode of Single Walled Carbon Nanotubes during Electrochemical Charging

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Kavan, Ladislav

    2009-01-01

    Roč. 113, č. 37 (2009), s. 16408-16413 ISSN 1932-7447 R&D Projects: GA ČR GC203/07/J067; GA AV ČR IAA400400911; GA AV ČR IAA400400804; GA AV ČR KAN200100801; GA MŠk LC510 Institutional research plan: CEZ:AV0Z40400503 Keywords : single-walled carbon nanotubes * radial breathing mode * electrochemistry Subject RIV: CG - Electrochemistry Impact factor: 4.224, year: 2009

  12. Conducting carbonized polyaniline nanotubes

    International Nuclear Information System (INIS)

    Mentus, Slavko; Ciric-Marjanovic, Gordana; Trchova, Miroslava; Stejskal, Jaroslav

    2009-01-01

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 deg. C min -1 up to a maximum temperature of 800 deg. C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 μm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 μm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm -1 , increased to 0.7 S cm -1 upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  13. Conducting carbonized polyaniline nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mentus, Slavko; Ciric-Marjanovic, Gordana [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11158 Belgrade (Serbia); Trchova, Miroslava; Stejskal, Jaroslav [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Square 2, 162 06 Prague 6 (Czech Republic)], E-mail: gordana@ffh.bg.ac.rs

    2009-06-17

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 deg. C min{sup -1} up to a maximum temperature of 800 deg. C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 {mu}m, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 {mu}m, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm{sup -1}, increased to 0.7 S cm{sup -1} upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  14. Gillnet Tag Program

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Certain fishery management programs require vessels to obtain gillnet tags to be used with their gillnet gear. Gillnet tag data is a collection of requests and...

  15. Cooperative Tagging Center (CTC)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Cooperative Tagging Center (CTC) began as the Cooperative Game Fish Tagging Program (GTP) at Woods Hole Oceanographic Institute (WHOI) in 1954. The GTP was...

  16. North Pacific Albacore Tagging

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Conventional tagging data are available from 1971 to 1996. Electronic tagging data are available from 2000 to present. The data are managed by SWFSC in Access...

  17. Raman spectroscopy

    Science.gov (United States)

    Raman spectroscopy has gained increased use and importance in recent years for accurate and precise detection of physical and chemical properties of food materials, due to the greater specificity and sensitivity of Raman techniques over other analytical techniques. This book chapter presents Raman s...

  18. Tagging vs. Controlled Vocabulary

    DEFF Research Database (Denmark)

    Bogers, Toine; Petras, Vivien

    2015-01-01

    The popularity of social tagging has sparked a great deal of debate on whether tags could replace or improve upon professional metadata as descriptors of books and other information objects. In this paper we present a large-scale empirical comparison of the contributions of individual information...... that tags and controlled vocabulary terms do not actually outperform each other consistently, but seem to provide complementary contributions: some information needs are best addressed using controlled vocabulary terms whereas other are best addressed using tags....

  19. Cutaneous skin tag

    Science.gov (United States)

    Skin tag; Acrochordon; Fibroepithelial polyp ... have diabetes. They are thought to occur from skin rubbing against skin. ... The tag sticks out of the skin and may have a short, narrow stalk connecting it to the surface of the skin. Some skin tags are as long as ...

  20. Towards Universal Semantic Tagging

    NARCIS (Netherlands)

    Abzianidze, Lasha; Bos, Johan

    2017-01-01

    The paper proposes the task of universal semantic tagging---tagging word tokens with language-neutral, semantically informative tags. We argue that the task, with its independent nature, contributes to better semantic analysis for wide-coverage multilingual text. We present the initial version of

  1. Extracting Tag Hierarchies

    Science.gov (United States)

    Tibély, Gergely; Pollner, Péter; Vicsek, Tamás; Palla, Gergely

    2013-01-01

    Tagging items with descriptive annotations or keywords is a very natural way to compress and highlight information about the properties of the given entity. Over the years several methods have been proposed for extracting a hierarchy between the tags for systems with a "flat", egalitarian organization of the tags, which is very common when the tags correspond to free words given by numerous independent people. Here we present a complete framework for automated tag hierarchy extraction based on tag occurrence statistics. Along with proposing new algorithms, we are also introducing different quality measures enabling the detailed comparison of competing approaches from different aspects. Furthermore, we set up a synthetic, computer generated benchmark providing a versatile tool for testing, with a couple of tunable parameters capable of generating a wide range of test beds. Beside the computer generated input we also use real data in our studies, including a biological example with a pre-defined hierarchy between the tags. The encouraging similarity between the pre-defined and reconstructed hierarchy, as well as the seemingly meaningful hierarchies obtained for other real systems indicate that tag hierarchy extraction is a very promising direction for further research with a great potential for practical applications. Tags have become very prevalent nowadays in various online platforms ranging from blogs through scientific publications to protein databases. Furthermore, tagging systems dedicated for voluntary tagging of photos, films, books, etc. with free words are also becoming popular. The emerging large collections of tags associated with different objects are often referred to as folksonomies, highlighting their collaborative origin and the “flat” organization of the tags opposed to traditional hierarchical categorization. Adding a tag hierarchy corresponding to a given folksonomy can very effectively help narrowing or broadening the scope of search

  2. Extracting tag hierarchies.

    Directory of Open Access Journals (Sweden)

    Gergely Tibély

    Full Text Available Tagging items with descriptive annotations or keywords is a very natural way to compress and highlight information about the properties of the given entity. Over the years several methods have been proposed for extracting a hierarchy between the tags for systems with a "flat", egalitarian organization of the tags, which is very common when the tags correspond to free words given by numerous independent people. Here we present a complete framework for automated tag hierarchy extraction based on tag occurrence statistics. Along with proposing new algorithms, we are also introducing different quality measures enabling the detailed comparison of competing approaches from different aspects. Furthermore, we set up a synthetic, computer generated benchmark providing a versatile tool for testing, with a couple of tunable parameters capable of generating a wide range of test beds. Beside the computer generated input we also use real data in our studies, including a biological example with a pre-defined hierarchy between the tags. The encouraging similarity between the pre-defined and reconstructed hierarchy, as well as the seemingly meaningful hierarchies obtained for other real systems indicate that tag hierarchy extraction is a very promising direction for further research with a great potential for practical applications. Tags have become very prevalent nowadays in various online platforms ranging from blogs through scientific publications to protein databases. Furthermore, tagging systems dedicated for voluntary tagging of photos, films, books, etc. with free words are also becoming popular. The emerging large collections of tags associated with different objects are often referred to as folksonomies, highlighting their collaborative origin and the "flat" organization of the tags opposed to traditional hierarchical categorization. Adding a tag hierarchy corresponding to a given folksonomy can very effectively help narrowing or broadening the scope of

  3. Extracting tag hierarchies.

    Science.gov (United States)

    Tibély, Gergely; Pollner, Péter; Vicsek, Tamás; Palla, Gergely

    2013-01-01

    Tagging items with descriptive annotations or keywords is a very natural way to compress and highlight information about the properties of the given entity. Over the years several methods have been proposed for extracting a hierarchy between the tags for systems with a "flat", egalitarian organization of the tags, which is very common when the tags correspond to free words given by numerous independent people. Here we present a complete framework for automated tag hierarchy extraction based on tag occurrence statistics. Along with proposing new algorithms, we are also introducing different quality measures enabling the detailed comparison of competing approaches from different aspects. Furthermore, we set up a synthetic, computer generated benchmark providing a versatile tool for testing, with a couple of tunable parameters capable of generating a wide range of test beds. Beside the computer generated input we also use real data in our studies, including a biological example with a pre-defined hierarchy between the tags. The encouraging similarity between the pre-defined and reconstructed hierarchy, as well as the seemingly meaningful hierarchies obtained for other real systems indicate that tag hierarchy extraction is a very promising direction for further research with a great potential for practical applications. Tags have become very prevalent nowadays in various online platforms ranging from blogs through scientific publications to protein databases. Furthermore, tagging systems dedicated for voluntary tagging of photos, films, books, etc. with free words are also becoming popular. The emerging large collections of tags associated with different objects are often referred to as folksonomies, highlighting their collaborative origin and the "flat" organization of the tags opposed to traditional hierarchical categorization. Adding a tag hierarchy corresponding to a given folksonomy can very effectively help narrowing or broadening the scope of search. Moreover

  4. Properties of single-walled carbon nanotube-based aerogels as a function of nanotube loading

    International Nuclear Information System (INIS)

    Worsley, Marcus A.; Pauzauskie, Peter J.; Kucheyev, Sergei O.; Zaug, Joseph M.; Hamza, Alex V.; Satcher, Joe H.; Baumann, Theodore F.

    2009-01-01

    Here, we present the synthesis and characterization of low-density single-walled carbon nanotube-based aerogels (SWNT-CA). Aerogels with varying nanotube loading (0-55 wt.%) and density (20-350 mg cm -3 ) were fabricated and characterized by four-probe method, electron microscopy, Raman spectroscopy and nitrogen porosimetry. Several properties of the SWNT-CAs were highly dependent upon nanotube loading. At nanotube loadings of 55 wt.%, shrinkage of the aerogel monoliths during carbonization and drying was almost completely eliminated. Electrical conductivities are improved by an order of magnitude for the SWNT-CA (55 wt.% nanotubes) compared to those of foams without nanotubes. Surface areas as high as 184 m 2 g -1 were achieved for SWNT-CAs with greater than 20 wt.% nanotube loading.

  5. Raman facility

    Data.gov (United States)

    Federal Laboratory Consortium — Raman scattering is a powerful light scattering technique used to diagnose the internal structure of molecules and crystals. In a light scattering experiment, light...

  6. Tags on healthcare information websites

    DEFF Research Database (Denmark)

    Lykke, Marianne; Ådland, Marit Kristine

    2018-01-01

    This paper explores tags and tagging behaviour on health information websites using an empirical, user-oriented, exploratory case study. Taggers and editors were interviewed about tags and tagging, while taggers solved tasks that included applying tags to a website. This qualitative data...... articles, request information, and value article content. Some of these show that tags are not only not only topical descriptions, but communicative by intent. This result can potentially inform the design of tagging features....

  7. Symmetry Properties of Single-Walled BC2N Nanotubes

    Directory of Open Access Journals (Sweden)

    Lin Jianyi

    2009-01-01

    Full Text Available Abstract The symmetry properties of the single-walled BC2N nanotubes were investigated. All the BC2N nanotubes possess nonsymmorphic line groups. In contrast with the carbon and boron nitride nanotubes, armchair and zigzag BC2N nanotubes belong to different line groups, depending on the index n (even or odd and the vector chosen. The number of Raman- active phonon modes is almost twice that of the infrared-active phonon modes for all kinds of BC2N nanotubes.

  8. Shortened carbon nanotubes and their influence on the electrical properties of polymer nanocomposites

    NARCIS (Netherlands)

    Inam, F.; Reece, M.J.; Peijs, A.A.J.M.

    2012-01-01

    Multi-wall carbon nanotubes of medium length (mCNTs) were aggressively tip-ultrasonicated to produce shortened and damaged carbon nanotubes (xCNTs). High-resolution electron microscopic analysis was performed to measure the dimensions of carbon nanotubes (CNTs). Thermo-gravimetric analysis and Raman

  9. PIT Tagging Anurans

    Science.gov (United States)

    McCreary, Brome

    2008-01-01

    The following video demonstrates a procedure to insert a passive integrated transponder (PIT) tag under the skin of an anuran (frog or toad) for research and monitoring purposes. Typically, a 12.5 mm tag (0.5 in.) is used to uniquely identify individual anurans as smal as 40 mm (1.6 in.) in length from snout to vent. Smaller tags are also available and allow smaller anurans to be tagged. The procedure does not differ for other sizes of tages or other sizes of anurans. Anyone using this procedure should ensure that the tag is small enough to fit easily behind the sacral hump of the anuran, as shown in this video.

  10. Enhancing Raman signals with an interferometrically controlled AFM tip

    International Nuclear Information System (INIS)

    Oron-Carl, Matti; Krupke, Ralph

    2013-01-01

    We demonstrate the upgrade of a commercial confocal Raman microscope into a tip-enhanced Raman microscope/spectroscopy system (TERS) by integrating an interferometrically controlled atomic force microscope into the base of an existing upright microscope to provide near-field detection and thus signal enhancement. The feasibility of the system is demonstrated by measuring the Raman near-field enhancement on thin PEDOT:PSS films and on carbon nanotubes within a device geometry. An enhancement factor of 2–3 and of 5–6 is observed, respectively. Moreover, on a nanotube device we show local conductivity measurement and its correlation to Raman and topography recordings. Upgrading an existing upright confocal Raman microscope in the demonstrated way is significantly cheaper than purchasing a complete commercial TERS system. (paper)

  11. Flavour Tagging at LHCb

    CERN Multimedia

    Grabalosa Gandara, M

    2009-01-01

    To do precise CP violation measurements, the most possible accurate knowledge of the flavour at production of the reconstructed B meson is required. This poster summarizes the flavour tagging performances for the LHCb experiment. We use same side an opposite side algorithms to establish wheter the meson contained a b or a b\\bar quark. The final decision is obtained through a combination of several methods. The use of control channels, decays to a flavour specific final state, will allow to determine the wrong tag fraction \\omega (the probability of a tag to be wrong), which can be used as input for the determination of CKM unitary triangle angles.

  12. Tagged Vector Contour (TVC)

    Data.gov (United States)

    Kansas Data Access and Support Center — The Kansas Tagged Vector Contour (TVC) dataset consists of digitized contours from the 7.5 minute topographic quadrangle maps. Coverage for the state is incomplete....

  13. Carbon nanotube network-silicon oxide non-volatile switches.

    Science.gov (United States)

    Liao, Albert D; Araujo, Paulo T; Xu, Runjie; Dresselhaus, Mildred S

    2014-12-08

    The integration of carbon nanotubes with silicon is important for their incorporation into next-generation nano-electronics. Here we demonstrate a non-volatile switch that utilizes carbon nanotube networks to electrically contact a conductive nanocrystal silicon filament in silicon dioxide. We form this device by biasing a nanotube network until it physically breaks in vacuum, creating the conductive silicon filament connected across a small nano-gap. From Raman spectroscopy, we observe coalescence of nanotubes during breakdown, which stabilizes the system to form very small gaps in the network~15 nm. We report that carbon nanotubes themselves are involved in switching the device to a high resistive state. Calculations reveal that this switching event occurs at ~600 °C, the temperature associated with the oxidation of nanotubes. Therefore, we propose that, in switching to a resistive state, the nanotube oxidizes by extracting oxygen from the substrate.

  14. Inclusive Flavour Tagging Algorithm

    International Nuclear Information System (INIS)

    Likhomanenko, Tatiana; Derkach, Denis; Rogozhnikov, Alex

    2016-01-01

    Identifying the flavour of neutral B mesons production is one of the most important components needed in the study of time-dependent CP violation. The harsh environment of the Large Hadron Collider makes it particularly hard to succeed in this task. We present an inclusive flavour-tagging algorithm as an upgrade of the algorithms currently used by the LHCb experiment. Specifically, a probabilistic model which efficiently combines information from reconstructed vertices and tracks using machine learning is proposed. The algorithm does not use information about underlying physics process. It reduces the dependence on the performance of lower level identification capacities and thus increases the overall performance. The proposed inclusive flavour-tagging algorithm is applicable to tag the flavour of B mesons in any proton-proton experiment. (paper)

  15. Optical trapping of carbon nanotubes and graphene

    Directory of Open Access Journals (Sweden)

    S. Vasi

    2011-09-01

    Full Text Available We study optical trapping of nanotubes and graphene. We extract the distribution of both centre-of-mass and angular fluctuations from three-dimensional tracking of these optically trapped carbon nanostructures. The optical force and torque constants are measured from auto and cross-correlation of the tracking signals. We demonstrate that nanotubes enable nanometer spatial, and femto-Newton force resolution in photonic force microscopy by accurately measuring the radiation pressure in a double frequency optical tweezers. Finally, we integrate optical trapping with Raman and photoluminescence spectroscopy demonstrating the use of a Raman and photoluminescence tweezers by investigating the spectroscopy of nanotubes and graphene flakes in solution. Experimental results are compared with calculations based on electromagnetic scattering theory.

  16. CV Raman

    Indian Academy of Sciences (India)

    formatted to take advantage of the changes in publishing methods in the past thirty ..... This work would not have been possible without the support and en- couragement of ..... in which Raman made his decision, have a deeper significance than .... Light in Water and the Colour of the Sea within a month of his return to India ...

  17. Raman Chandrasekar

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education. Raman Chandrasekar. Articles written in Resonance – Journal of Science Education. Volume 13 Issue 5 May 2008 pp 430-439 General Article. How Children Learn to Use Language - An Overview of R. Narasimhan's Ideas on Child Language Acquisition.

  18. Personalization of tagging systems

    NARCIS (Netherlands)

    J. Wang (Jun); M. Clements (Maarten); J. Yang; A.P. de Vries (Arjen); M.J.T. Reinders

    2010-01-01

    htmlabstractSocial media systems have encouraged end user participation in the Internet, for the purpose of storing and distributing Internet content, sharing opinions and maintaining relationships. Collaborative tagging allows users to annotate the resulting user-generated content, and enables

  19. TagPad

    DEFF Research Database (Denmark)

    Bornoe, Nis; Barkhuus, Louise

    2013-01-01

    The area of cyberinfrastructures has looked extensively at research within the natural sciences, however, the social sciences have been largely overlooked in terms of novel data collection and analysis systems. We developed a probe tool, TagPad, to look at the process for social science data...

  20. Ontologies and tag-statistics

    Science.gov (United States)

    Tibély, Gergely; Pollner, Péter; Vicsek, Tamás; Palla, Gergely

    2012-05-01

    Due to the increasing popularity of collaborative tagging systems, the research on tagged networks, hypergraphs, ontologies, folksonomies and other related concepts is becoming an important interdisciplinary area with great potential and relevance for practical applications. In most collaborative tagging systems the tagging by the users is completely ‘flat’, while in some cases they are allowed to define a shallow hierarchy for their own tags. However, usually no overall hierarchical organization of the tags is given, and one of the interesting challenges of this area is to provide an algorithm generating the ontology of the tags from the available data. In contrast, there are also other types of tagged networks available for research, where the tags are already organized into a directed acyclic graph (DAG), encapsulating the ‘is a sub-category of’ type of hierarchy between each other. In this paper, we study how this DAG affects the statistical distribution of tags on the nodes marked by the tags in various real networks. The motivation for this research was the fact that understanding the tagging based on a known hierarchy can help in revealing the hidden hierarchy of tags in collaborative tagging systems. We analyse the relation between the tag-frequency and the position of the tag in the DAG in two large sub-networks of the English Wikipedia and a protein-protein interaction network. We also study the tag co-occurrence statistics by introducing a two-dimensional (2D) tag-distance distribution preserving both the difference in the levels and the absolute distance in the DAG for the co-occurring pairs of tags. Our most interesting finding is that the local relevance of tags in the DAG (i.e. their rank or significance as characterized by, e.g., the length of the branches starting from them) is much more important than their global distance from the root. Furthermore, we also introduce a simple tagging model based on random walks on the DAG, capable of

  1. Ontologies and tag-statistics

    International Nuclear Information System (INIS)

    Tibély, Gergely; Vicsek, Tamás; Pollner, Péter; Palla, Gergely

    2012-01-01

    Due to the increasing popularity of collaborative tagging systems, the research on tagged networks, hypergraphs, ontologies, folksonomies and other related concepts is becoming an important interdisciplinary area with great potential and relevance for practical applications. In most collaborative tagging systems the tagging by the users is completely ‘flat’, while in some cases they are allowed to define a shallow hierarchy for their own tags. However, usually no overall hierarchical organization of the tags is given, and one of the interesting challenges of this area is to provide an algorithm generating the ontology of the tags from the available data. In contrast, there are also other types of tagged networks available for research, where the tags are already organized into a directed acyclic graph (DAG), encapsulating the ‘is a sub-category of’ type of hierarchy between each other. In this paper, we study how this DAG affects the statistical distribution of tags on the nodes marked by the tags in various real networks. The motivation for this research was the fact that understanding the tagging based on a known hierarchy can help in revealing the hidden hierarchy of tags in collaborative tagging systems. We analyse the relation between the tag-frequency and the position of the tag in the DAG in two large sub-networks of the English Wikipedia and a protein-protein interaction network. We also study the tag co-occurrence statistics by introducing a two-dimensional (2D) tag-distance distribution preserving both the difference in the levels and the absolute distance in the DAG for the co-occurring pairs of tags. Our most interesting finding is that the local relevance of tags in the DAG (i.e. their rank or significance as characterized by, e.g., the length of the branches starting from them) is much more important than their global distance from the root. Furthermore, we also introduce a simple tagging model based on random walks on the DAG, capable of

  2. Growth of anatase titanium dioxide nanotubes via anodization

    Directory of Open Access Journals (Sweden)

    Ed Adrian Dilla

    2012-06-01

    Full Text Available In this work, titanium dioxide nanotubes were grown via anodization of sputtered titanium thin films using different anodization parameters in order to formulate a method of producing long anatase titanium dioxide nanotubes intended for solar cell applications. The morphological features of the nanotubes grown via anodization were explored using a Philips XL30 Field Emission Scanning Electron Microscope. Furthermore, the grown nanotubes were also subjected to X-ray diffraction and Raman spectroscopy in order to investigate the effect of the predominant crystal orientation of the parent titanium thin film on the crystal phase of the nanotubes. After optimizing the anodization parameters, nanotubes with anatase TiO2 crystal phase and tube length more than 2 microns was produced from parent titanium thin films with predominant Ti(010 crystal orientation and using ammonium fluoride in ethylene glycol as an electrolyte with a working voltage equal to 60V during 1-hour anodization runs.

  3. Phonon spectra, electronic, and thermodynamic properties of WS2 nanotubes.

    Science.gov (United States)

    Evarestov, Robert A; Bandura, Andrei V; Porsev, Vitaly V; Kovalenko, Alexey V

    2017-11-15

    Hybrid density functional theory calculations are performed for the first time on the phonon dispersion and thermodynamic properties of WS 2 -based single-wall nanotubes. Symmetry analysis is presented for phonon modes in nanotubes using the standard (crystallographic) factorization for line groups. Symmetry and the number of infra-red and Raman active modes in achiral WS 2 nanotubes are given for armchair and zigzag chiralities. It is demonstrated that a number of infrared and Raman active modes is independent on the nanotube diameter. The zone-folding approach is applied to find out an impact of curvature on electron and phonon band structure of nanotubes rolled up from the monolayer. Phonon frequencies obtained both for layers and nanotubes are used to compute the thermal contributions to their thermodynamic functions. The temperature dependences of energy, entropy, and heat capacity of nanotubes are estimated with respect to those of the monolayer. The role of phonons in the stability estimation of nanotubes is discussed based on Helmholtz free energy calculations. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  4. The role of tag suggestions in folksonomies

    NARCIS (Netherlands)

    Bollen, D.G.F.M.; Halpin, H.

    2009-01-01

    Most tagging systems support the user in the tag selection process by providing tag suggestions, or recommendations, based on a popularity measurement of tags other users provided when tagging the same resource. The majority of theories and mathematical models of tagging found in the literature

  5. Tag-elese or The Language of Tags

    Directory of Open Access Journals (Sweden)

    Jan Simons

    2008-01-01

    Full Text Available The core "meme" of Web 2.0 from which almost all other memes radiated was: 'You control your own data' (O'Reilly, 2005, 3. Key instruments for this user control are tagging systems that allow users to freely assign keywords of their own choosing to Internet resources of their own making as well as to documents produced by others. Of course, freely chosen keywords tags do not necessarily follow prefixed taxonomies or classification systems. But going by the maxim that interaction creates similarity and similarity creates interaction, the idea - or hope - is, however, that the tagging practices of individual users will eventually converge into an emergent common vocabulary or folksonomy (Merholz, 2004; Shirky, 2005; Vander Wal, 2005b; Mika, 2007. It is far from clear, however, that free tagging systems will eventually yield controlled vocabularies, and there are many incentives for idiosyncratic, ambiguous, and inconsistent uses of tags. Left to themselves, free tagging systems seem to be too wild and too chaotic for any order to emerge. But are these free tagging systems really as "feral" as they seem to be, or do they only look uncontrolled because one has been looking for order in the wrong place? I have done a quick-and-dirty" analysis of Flickr's tag cloud. The concept was: if folksonomies encourage users to tap on their own vernacular, everyday natural language must somehow "guide" the tagging practices of users of tagging systems. Flickr's tag cloud has been choosen because it may teach us something about tagging systems and folksonomies, and not - or not primarily - because of what tags may tell us about pictures.

  6. Direct growth of vertically aligned carbon nanotubes on silicon substrate by spray pyrolysis of Glycine max oil

    Directory of Open Access Journals (Sweden)

    K. T. Karthikeyan

    2017-11-01

    Full Text Available Vertically aligned carbon nanotubes have been synthesized by spray pyrolysis from Glycine max oil on silicon substrate using ferrocene as catalyst at 650 °C. Glycine max oil, a plant-based hydrocarbon precursor was used as a source of carbon and argon as a carrier gas. The as-grown vertically aligned carbon nanotubes were characterized by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, and Raman spectroscopy. Scanning electron microscopic images reveal that the dense bundles of aligned carbon nanotubes. High resolution transmission electron microscopy and Raman spectroscopy observations indicate that as-grown aligned carbon nanotubes are well graphitized.

  7. The use of external electronic tags on fish: an evaluation of tag retention and tagging effects

    DEFF Research Database (Denmark)

    Jepsen, Niels; Thorstad, Eva B.; Havn, Torgeir

    2015-01-01

    External tagging of fish with electronic tags has been used for decades for a wide range of marine and freshwater species. In the early years of fish telemetry research, it was the most commonly used attachment method, but later internal implants became preferred. Recently, the number of telemetry...... unsuitable for surgical implantation, or when using tags with sensors recording the external environment. The most commonly reported problems with external tags are tissue damage, premature tag loss, and decreased swimming capacity, but the effects are highly context dependent and species specific. Reduced......, but particularly there are few studies on predation risk, social interactions, and studies distinguishing capture and handling effects from tagging effects. For PSATs, especially those that are large relative to fish size, there are particular problems with a high proportion of premature tag losses, reduced...

  8. Electrochemical properties of double wall carbon nanotube electrodes

    OpenAIRE

    Pumera, Martin

    2007-01-01

    AbstractElectrochemical properties of double wall carbon nanotubes (DWNT) were assessed and compared to their single wall (SWNT) counterparts. The double and single wall carbon nanotube materials were characterized by Raman spectroscopy, scanning and transmission electron microscopy and electrochemistry. The electrochemical behavior of DWNT film electrodes was characterized by using cyclic voltammetry of ferricyanide and NADH. It is shown that while both DWNT and SWNT were significantly funct...

  9. Social Tagging of Mission Data

    Science.gov (United States)

    Norris, Jeffrey S.; Wallick, Michael N.; Joswig, Joseph C.; Powell, Mark W.; Torres, Recaredo J.; Mittman, David S.; Abramyan, Lucy; Crockett, Thomas M.; Shams, Khawaja S.; Fox, Jason M.; hide

    2010-01-01

    Mars missions will generate a large amount of data in various forms, such as daily plans, images, and scientific information. Often, there is a semantic linkage between images that cannot be captured automatically. Software is needed that will provide a method for creating arbitrary tags for this mission data so that items with a similar tag can be related to each other. The tags should be visible and searchable for all users. A new routine was written to offer a new and more flexible search option over previous applications. This software allows users of the MSLICE program to apply any number of arbitrary tags to a piece of mission data through a MSLICE search interface. The application of tags creates relationships between data that did not previously exist. These tags can be easily removed and changed, and contain enough flexibility to be specifically configured for any mission. This gives users the ability to quickly recall or draw attention to particular pieces of mission data, for example: Give a semantic and meaningful description to mission data; for example, tag all images with a rock in them with the tag "rock." Rapidly recall specific and useful pieces of data; for example, tag a plan as"driving template." Call specific data to a user s attention; for example, tag a plan as "for:User." This software is part of the MSLICE release, which was written in Java. It will run on any current Windows, Macintosh, or Linux system.

  10. Carbon nanotube: the inside story.

    Science.gov (United States)

    Ando, Yoshinori

    2010-06-01

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

  11. EDITORIAL: Focus on Carbon Nanotubes

    Science.gov (United States)

    2003-09-01

    planes to stable loops caused by annealing M Endo, B J Lee, Y A Kim, Y J Kim, H Muramatsu, T Yanagisawa, T Hayashi, M Terrones and M S Dresselhaus Energetics and electronic structure of C70-peapods and one-dimensional chains of C70 Susumu Okada, Minoru Otani and Atsushi Oshiyama Theoretical characterization of several models of nanoporous carbon F Valencia, A H Romero, E Hernández, M Terrones and H Terrones First-principles molecular dynamics study of the stretching frequencies of hydrogen molecules in carbon nanotubes Gabriel Canto, Pablo Ordejón, Cheng Hansong, Alan C Cooper and Guido P Pez The geometry and the radial breathing mode of carbon nanotubes: beyond the ideal behaviour Jeno Kürti, Viktor Zólyomi, Miklos Kertesz and Sun Guangyu Curved nanostructured materials Humberto Terrones and Mauricio Terrones A one-dimensional Ising model for C70 molecular ordering in C70-peapods Yutaka Maniwa, Hiromichi Kataura, Kazuyuki Matsuda and Yutaka Okabe Nanoengineering of carbon nanotubes for nanotools Yoshikazu Nakayama and Seiji Akita Narrow diameter double-wall carbon nanotubes: synthesis, electron microscopy and inelastic light scattering R R Bacsa, E Flahaut, Ch Laurent, A Peigney, S Aloni, P Puech and W S Bacsa Sensitivity of single multiwalled carbon nanotubes to the environment M Krüger, I Widmer, T Nussbaumer, M Buitelaar and C Schönenberger Characterizing carbon nanotube samples with resonance Raman scattering A Jorio, M A Pimenta, A G Souza Filho, R Saito, G Dresselhaus and M S Dresselhaus FTIR-luminescence mapping of dispersed single-walled carbon nanotubes Sergei Lebedkin, Katharina Arnold, Frank Hennrich, Ralph Krupke, Burkhard Renker and Manfred M Kappes Structural properties of Haeckelite nanotubes Ph Lambin and L P Biró Structural changes in single-walled carbon nanotubes under non-hydrostatic pressures: x-ray and Raman studies Sukanta Karmakar, Surinder M Sharma, P V Teredesai, D V S Muthu, A Govindaraj, S K Sikka and A K Sood Novel properties of 0

  12. Resonance Raman spectroscopy in one-dimensional carbon materials

    Directory of Open Access Journals (Sweden)

    Dresselhaus Mildred S.

    2006-01-01

    Full Text Available Brazil has played an important role in the development and use of resonance Raman spectroscopy as a powerful characterization tool for materials science. Here we present a short history of Raman scattering research in Brazil, highlighting the important contributions to the field coming from Brazilian researchers in the past. Next we discuss recent and important contributions where Brazil has become a worldwide leader, that is on the physics of quasi-one dimensional carbon nanotubes. We conclude this article by presenting results from a very recent resonance Raman study of exciting new materials, that are strictly one-dimensional carbon chains formed by the heat treatment of very pure double-wall carbon nanotube samples.

  13. Nanotube cathodes.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

    2006-11-01

    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  14. Nanotube cathodes

    International Nuclear Information System (INIS)

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

    2006-01-01

    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  15. Antenna for passive RFID tags

    Science.gov (United States)

    Schiopu, Paul; Manea, Adrian; Cristea, Ionica; Grosu, Neculai; Vladescu, Marian; Craciun, Anca-Ileana; Craciun, Alexandru

    2015-02-01

    Minuscule devices, called RFID tags are attached to objects and persons and emit information which positioned readers may capture wirelessly. Many methods of identification have been used, but that of most common is to use a unique serial number for identification of person or object. RFID tags can be characterized as either active or passive [1,2]. Traditional passive tags are typically in "sleep" state until awakened by the reader's emitted field. In passive tags, the reader's field acts to charge the capacitor that powers the badge and this can be a combination of antenna and barcodes obtained with SAW( Surface Acoustic Wave) devices [1,2,3] . The antenna in an RFID tag is a conductive element that permits the tag to exchange data with the reader. The paper contribution are targeted to antenna for passive RFID tags. The electromagnetic field generated by the reader is somehow oriented by the reader antenna and power is induced in the tag only if the orientation of the tag antenna is appropriate. A tag placed orthogonal to the reader yield field will not be read. This is the reason that guided manufacturers to build circular polarized antenna capable of propagating a field that is alternatively polarized on all planes passing on the diffusion axis. Passive RFID tags are operated at the UHF frequencies of 868MHz (Europe) and 915MHz (USA) and at the microwave frequencies of 2,45 GHz and 5,8 GHz . Because the tags are small dimensions, in paper, we present the possibility to use circular polarization microstrip antenna with fractal edge [2].

  16. Nuclear studies with tagged photons

    International Nuclear Information System (INIS)

    Axel, P.

    1979-01-01

    First, the photon tagging technique will be described schematically, and a brief history of photon tagging will be given, including the 20 year development of this technique at Illinois. In the second part some typical operating conditions will be indicated for our tagged photon facility. The final section of this paper will illustrate some types of experiments by showing data obtained recently. (KBE) 891 KBE/KBE 892 ARA

  17. Selective Etching of Thin Single-Walled Carbon Nanotubes

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Kavan, Ladislav; Dunsch, L.

    2009-01-01

    Roč. 131, č. 12 (2009), s. 4529-4534 ISSN 0002-7863 R&D Projects: GA AV ČR IAA400400804; GA ČR GC203/07/J067; GA AV ČR IAA400400911 Institutional research plan: CEZ:AV0Z40400503 Keywords : carbon nanotubes * Raman spectroelectrochemistry * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 8.580, year: 2009

  18. Buddy Tag CONOPS and Requirements.

    Energy Technology Data Exchange (ETDEWEB)

    Brotz, Jay Kristoffer [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Deland, Sharon M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-12-01

    This document defines the concept of operations (CONOPS) and the requirements for the Buddy Tag, which is conceived and designed in collaboration between Sandia National Laboratories and Princeton University under the Department of State Key VerificationAssets Fund. The CONOPS describe how the tags are used to support verification of treaty limitations and is only defined to the extent necessary to support a tag design. The requirements define the necessary functions and desired non-functional features of the Buddy Tag at a high level

  19. Flavour tagging performance in LHCb

    International Nuclear Information System (INIS)

    Grabalosa Gandara, Marc

    2009-01-01

    To do precise CP violation measurements, the best possible determination of the flavour of the B-meson is necessary. This report summarizes the flavour tagging performances for the LHCb experiment. The flavour tagging is obtained through a combination of several methods, based on different signatures. The use of control channels, which are decays to flavour-specific final states, will allow to determine the wrong tag fraction ω (the probability of a tag to be wrong), which can be used as an input for the determination of CKM unitarity triangle angles.

  20. A thermodynamic model for growth mechanisms of multiwall carbon nanotubes.

    Energy Technology Data Exchange (ETDEWEB)

    Kaatz, Forrest H.; Overmyer, Donald L.; Siegal, Michael P.

    2006-02-01

    Multiwall carbon nanotubes are grown via thermal chemical vapor deposition between temperatures of 630 and 830 C using acetylene in nitrogen as the carbon source. This process is modeled using classical thermodynamics to explain the total carbon deposition as a function of time and temperature. An activation energy of 1.60 eV is inferred for nanotube growth after considering the carbon solubility term. Scanning electron microscopy shows growth with diameters increasing linearly with time. Transmission electron microscopy and Raman spectroscopy show multiwall nanotubes surrounded by a glassy-carbon sheath, which grows with increasing wall thickness as growth temperatures and times rise.

  1. Thermodynamic model for growth mechanisms of multiwall carbon nanotubes

    Science.gov (United States)

    Kaatz, F. H.; Siegal, M. P.; Overmyer, D. L.; Provencio, P. P.; Tallant, D. R.

    2006-12-01

    Multiwall carbon nanotubes are grown via thermal chemical vapor deposition between temperatures of 630 and 830°C using acetylene in nitrogen as the carbon source. This process is modeled using classical thermodynamics to explain the total carbon deposition as a function of time and temperature. An activation energy of 1.60eV is inferred for nanotube growth after considering the carbon solubility term. Scanning electron microscopy shows growth with diameters increasing linearly with time. Transmission electron microscopy and Raman spectroscopy show multiwall nanotubes surrounded by a glassy-carbon sheath, which grows with increasing wall thickness as growth temperatures and times rise.

  2. Carbon Nanostructures for Tagging in Electrochemical Biosensing: A Review

    Directory of Open Access Journals (Sweden)

    Paloma Yáñez-Sedeño

    2017-01-01

    Full Text Available Growing demand for developing ultrasensitive electrochemical bioassays has led to the design of numerous signal amplification strategies. In this context, carbon-based nanomaterials have been demonstrated to be excellent tags for greatly amplifying the transduction of recognition events and simplifying the protocols used in electrochemical biosensing. This relevant role is due to the carbon-nanomaterials’ large surface area, excellent biological compatibility and ease functionalization and, in some cases, intrinsic electrochemistry. These carbon-based nanomaterials involve well-known carbon nanotubes (CNTs and graphene as well as the more recent use of other carbon nanoforms. This paper briefly discusses the advantages of using carbon nanostructures and their hybrid nanocomposites for amplification through tagging in electrochemical biosensing platforms and provides an updated overview of some selected examples making use of labels involving carbon nanomaterials, acting both as carriers for signal elements and as electrochemical tracers, applied to the electrochemical biosensing of relevant (biomarkers.

  3. Multifunctional carbon nanotubes with nanoparticles embedded in their walls

    International Nuclear Information System (INIS)

    Mattia, D; Korneva, G; Sabur, A; Friedman, G; Gogotsi, Y

    2007-01-01

    Controlled amounts of nanoparticles ranging in size and composition were embedded in the walls of carbon nanotubes during a template-assisted chemical vapour deposition (CVD) process. The encapsulation of gold nanoparticles enabled surface enhanced Raman spectroscopy (SERS) detection of glycine inside the cavity of the nanotubes. Iron oxide particles are partially reduced to metallic iron during the CVD process giving the nanotubes ferromagnetic behaviour. At high nanoparticle concentrations, particle agglomerates can form. These agglomerates or larger particles, which are only partially embedded in the walls of the nanotubes, are covered by additional carbon layers inside the hollow cavity of the tube producing hillocks inside the nanotubes, with sizes comparable to the bore of the tube

  4. In situ tribochemical sulfurization of molybdenum oxide nanotubes.

    Science.gov (United States)

    Rodríguez Ripoll, Manel; Tomala, Agnieszka; Gabler, Christoph; DraŽić, Goran; Pirker, Luka; Remškar, Maja

    2018-02-15

    MoS 2 nanoparticles are typically obtained by high temperature sulfurization of organic and inorganic precursors under a S rich atmosphere and have excellent friction reduction properties. We present a novel approach for making the sulfurization unnecessary for MoO 3 nanotubes during the synthesis process for friction and wear reduction applications while simultaneously achieving a superb tribological performance. To this end, we report the first in situ sulfurization of MoO 3 nanotubes during sliding contact in the presence of sulfur-containing lubricant additives. The sulfurization leads to the tribo-chemical formation of a MoS 2 -rich low-friction tribofilm as verified using Raman spectroscopy and can be achieved both during sliding contact and under extreme pressure conditions. Under sliding contact conditions, MoO 3 nanotubes in synergy with sulfurized olefin polysulfide and pre-formed zinc dialkyl dithiophosphate tribofilms achieve an excellent friction performance. Under these conditions, the tribochemical sulfurization of MoO 3 nanotubes leads to a similar coefficient of friction to the one obtained using a model nanolubricant containing MoS 2 nanotubes. Under extreme pressure conditions, the in situ sulfurization of MoO 3 nanotubes using sulfurized olefin polysulfide results in a superb load carrying capacity capable of outperforming MoS 2 nanotubes. The reason is that while MoO 3 nanotubes are able to continuously sulfurize during sliding contact conditions, MoS 2 nanotubes progressively degrade by oxidation thus losing lubricity.

  5. LHCb Tag Collector

    International Nuclear Information System (INIS)

    Fernández, Paloma Fuente; Clemencic, Marco; Cousin, Nicolas

    2011-01-01

    The LHCb physics software consists of hundreds of packages, each of which is developed by one or more physicists. When the developers have some code changes that they would like released, they commit them to the version control system, and enter the revision number into a database. These changes have to be integrated into a new release of each of the physics analysis applications. Tests are then performed by a nightly build system, which rebuilds various configurations of the whole software stack and executes a suite of run-time functionality tests. A Tag Collector system has been developed using solid standard technologies to cover both the use cases of developers and integration managers. A simple Web interface, based on an AJAX-like technology, is available. Integration with SVN and Nightly Build System, is possible via a Python API. Data are stored in a relational database with the help of an ORM (Object-Relational Mapping) library.

  6. Internally readable identifying tag

    International Nuclear Information System (INIS)

    Jefferts, K.B.; Jefferts, E.R.

    1980-01-01

    A method of identifying non-metallic objects by means of X-ray equipment is described in detail. A small metal pin with a number of grooves cut in a pre-determined equi-spaced pattern is implanted into the non-metallic object and by decoding the groove patterns using X-ray equipment, the object is uniquely identified. A specific example of such an application is in studying the migratory habits of fish. The pin inserted into the snout of the fish is 0.010 inch in diameter, 0.040 inch in length with 8 possible positions for grooves if spaced 0.005 inch apart. With 6 of the groove positions available for data, the capacity is 2 6 or 64 combinations; clearly longer pins would increase the data capacity. This method of identification is a major advance over previous techniques which necessitated destruction of the fish in order to recover the identification tag. (UK)

  7. Optical trapping and Raman spectroscopy of single nanostructures using standing-wave Raman tweezers

    Science.gov (United States)

    Wu, Mu-ying; He, Lin; Chen, Gui-hua; Yang, Guang; Li, Yong-qing

    2017-08-01

    Optical tweezers integrated with Raman spectroscopy allows analyzing a single trapped micro-particle, but is generally less effective for individual nano-sized objects in the 10-100 nm range. The main challenge is the weak gradient force on nanoparticles that is insufficient to overcome the destabilizing effect of scattering force and Brownian motion. Here, we present standing-wave Raman tweezers for stable trapping and sensitive characterization of single isolated nanostructures with a low laser power by combining a standing-wave optical trap (SWOT) with confocal Raman spectroscopy. This scheme has stronger intensity gradients and balanced scattering forces, and thus is more stable and sensitive in measuring nanoparticles in liquid with 4-8 fold increase in the Raman signals. It can be used to analyze many nanoparticles that cannot be measured with single-beam Raman tweezers, including individual single-walled carbon nanotubes (SWCNT), graphene flakes, biological particles, polystyrene beads (100 nm), SERS-active metal nanoparticles, and high-refractive semiconductor nanoparticles with a low laser power of a few milliwatts. This would enable sorting and characterization of specific SWCNTs and other nanoparticles based on their increased Raman fingerprints.

  8. Optical Characterization and Applications of Single Walled Carbon Nanotubes

    Science.gov (United States)

    Strano, Michael S.

    2005-03-01

    Recent advances in the dispersion and separation of single walled carbon nanotubes have led to new methods of optical characterization and some novel applications. We find that Raman spectroscopy can be used to probe the aggregation state of single-walled carbon nanotubes in solution or as solids with a range of varying morphologies. Carbon nanotubes experience an orthogonal electronic dispersion when in electrical contact that broadens (from 40 meV to roughly 80 meV) and shifts the interband transition to lower energy (by 60 meV). We show that the magnitude of this shift is dependent on the extent of bundle organization and the inter-nanotube contact area. In the Raman spectrum, aggregation shifts the effective excitation profile and causes peaks to increase or decrease, depending on where the transition lies, relative to the excitation wavelength. The findings are particularly relevant for evaluating nanotube separation processes, where relative peak changes in the Raman spectrum can be confused for selective enrichment. We have also used gel electrophoresis and column chromatography conducted on individually dispersed, ultrasonicated single-walled carbon nanotubes to yield simultaneous separation by tube length and diameter. Electroelution after electrophoresis is shown to produce highly resolved fractions of nanotubes with average lengths between 92 and 435 nm. Separation by diameter is concomitant with length fractionation, and nanotubes that have been cut shortest also possess the greatest relative enrichments of large-diameter species. The relative quantum yield decreases nonlinearly as the nanotube length becomes shorter. These findings enable new applications of nanotubes as sensors and biomarkers. Particularly, molecular detection using near infrared (n-IR) light between 0.9 and 1.3 eV has important biomedical applications because of greater tissue penetration and reduced auto-fluorescent background in thick tissue or whole blood media. Carbon nanotubes

  9. Nanotube phonon waveguide

    Science.gov (United States)

    Chang, Chih-Wei; Zettl, Alexander K.

    2013-10-29

    Disclosed are methods and devices in which certain types of nanotubes (e.g., carbon nanotubes and boron nitride nanotubes conduct heat with high efficiency and are therefore useful in electronic-type devices.

  10. Vertically aligned multiwalled carbon nanotubes as electronic interconnects

    Science.gov (United States)

    Gopee, Vimal Chandra

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

  11. Engineering the ATLAS TAG Browser

    CERN Document Server

    Zhang, Q; The ATLAS collaboration

    2011-01-01

    ELSSI is a web-based event metadata (TAG) browser and event-level selection service for ATLAS. TAGs from all ATLAS physics and Monte Carlo data sets are routinely loaded into Oracle databases as an integral part of event processing. As data volumes increase, more and more sites are joining the distributed TAG data hosting topology[1]. Meanwhile, TAG content and database schemata continue to evolve as new user requirements and additional sources of metadata emerge. All of this has posed many challenges to the development of ELSSI, which must support vast amounts of TAG data while source, content, geographic locations, and user query patterns may change over time. In this paper, we describe some of the challenges encountered in the process of developing ELSSI, and the software engineering strategies adopted to address those challenges. Approaches to management of access to data, browsing, data rendering, query building, query validation, execution, connection management, and communication with auxiliary service...

  12. Engineering the ATLAS TAG Browser

    CERN Document Server

    Zhang, Q; The ATLAS collaboration

    2011-01-01

    ELSSI is a web-based event metadata (TAG) browser and event-level selection service for ATLAS. TAGs from all ATLAS physics and Monte Carlo data sets are routinely loaded into Oracle databases as an integral part of event processing. As data volumes increase, more and more sites are joining the distributed TAG data hosting topology. Meanwhile, TAG content and database schemata continue to evolve as new user requirements and additional sources of metadata emerge. All of this has posed many challenges to the development of ELSSI, which must support vast amounts of TAG data while source, content, geographic locations, and user query patterns may change over time. In this paper, we describe some of the challenges encountered in the process of developing ELSSI, and the software engineering strategies adopted to address those challenges. Approaches to management of access to data, browsing, data rendering, query building, query validation, execution, connection management, and communication with auxiliary services a...

  13. Raman spectroscopy of triolein under high pressures

    Science.gov (United States)

    Tefelski, D. B.; Jastrzębski, C.; Wierzbicki, M.; Siegoczyński, R. M.; Rostocki, A. J.; Wieja, K.; Kościesza, R.

    2010-03-01

    This article presents results of the high pressure Raman spectroscopy of triolein. Triolein, a triacylglyceride (TAG) of oleic acid, is an unsaturated fat, present in natural oils such as olive oil. As a basic food component and an energy storage molecule, it has considerable importance for food and fuel industries. To generate pressure in the experiment, we used a high-pressure cylindrical chamber with sapphire windows, presented in (R.M. Siegoczyński, R. Kościesza, D.B. Tefelski, and A. Kos, Molecular collapse - modification of the liquid structure induced by pressure in oleic acid, High Press. Res. 29 (2009), pp. 61-66). Pressure up to 750 MPa was applied. A Raman spectrometer in "macro"-configuration was employed. Raman spectroscopy provides information on changes of vibrational modes related to structural changes of triolein under pressure. Interesting changes in the triglyceride C‒H stretching region at 2650-3100 cm-1 were observed under high-pressures. Changes were also observed in the ester carbonyl (C˭ O) stretching region 1700-1780 cm-1 and the C‒C stretching region at 1050-1150 cm-1. The overall luminescence of the sample decreased under pressure, making it possible to set longer spectrum acquisition time and obtain more details of the spectrum. The registered changes suggest that the high-pressure solid phase of triolein is organized as β-polymorphic, as was reported in (C. Akita, T. Kawaguchi, and F. Kaneko, Structural study on polymorphism of cis-unsaturated triacylglycerol: Triolein, J. Phys. Chem. B 110 (2006), pp. 4346-4353; E. Da Silva and D. Rousseau, Molecular order and thermodynamics of the solid-liquid transition in triglycerides via Raman spectroscopy, Phys. Chem. Chem. Phys. 10 (2008), pp. 4606-4613) (with temperature-induced phase transitions). The research has shown that Raman spectroscopy in TAGs under pressure reveals useful information about its structural changes.

  14. Application of Conductive Carbon Nanotube Fibers and Composites: Gas Sensor

    Science.gov (United States)

    2013-05-01

    changes in Raman spectroscopy data when single wall carbon nanotubes (SWNT) are immersed in various liquids, including common organics (12). In...Resistance -- (82) 2007 Su H2O MWNT PMMA, KOH Gas Impedance -- (83) 2011 Tang H2O MWNT PI Gas Resistance -- (84) 2003 Wang H2O2, NADH SWNT

  15. Carbon Nanotube Electrodes for Hot-Wire Electrochemistry

    Czech Academy of Sciences Publication Activity Database

    Gründler, P.; Frank, Otakar; Kavan, Ladislav; Dunsch, L.

    2009-01-01

    Roč. 10, č. 3 (2009), s. 559-563 ISSN 1439-4235 R&D Projects: GA AV ČR IAA400400804; GA AV ČR KAN200100801 Institutional research plan: CEZ:AV0Z40400503 Keywords : electrochemistry * electrodes * nanotubes * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 3.453, year: 2009

  16. The effects of nanostructures on the mechanical and tribological properties of TiO2 nanotubes

    Science.gov (United States)

    Yoon, Yeoungchin; Park, Jeongwon

    2018-04-01

    TiO2 nanotubes were prepared by anodization on Ti substrates with a diameter variation of 30-100 nm, and the structure of the nanotubes were studied using x-ray diffraction and Raman spectroscopy, which confirmed the structure changes from the anatase phase to the rutile phase of TiO2 at a diameter below 50 nm. The tribological behaviors of TiO2 nanotubes were investigated with different diameters. The effectiveness of the rutile phase and the diameter size enhanced the frictional performance of TiO2 nanotubes.

  17. Femtosecond laser ablation of single-wall carbon nanotube-based material

    International Nuclear Information System (INIS)

    Danilov, Pavel A; Ionin, Andrey A; Kudryashov, Sergey I; Makarov, Sergey V; Mel’nik, Nikolay N; Rudenko, Andrey A; Yurovskikh, Vladislav I; Zayarny, Dmitry V; Lednev, Vasily N; Obraztsova, Elena D; Pershin, Sergey M; Bunkin, Alexey F

    2014-01-01

    Single- and multi-shot femtosecond laser surface ablation of a single-wall carbon nanotube-based substrate at 515- and 1030 nm wavelengths was studied by scanning electron microscopy and micro-Raman spectroscopy. The laser ablation proceeds in two ways: as the low-fluence mesoscopic shallow disintegration of the surface nanotube packing, preserving the individual integrity and the semiconducting character of the nanotubes or as the high-fluence deep material removal apparently triggered by the strong intrinsic or impurity-mediated ablation of the individual carbon nanotubes on the substrate surface. (letter)

  18. Polarized tagged photons

    International Nuclear Information System (INIS)

    Maximon, L.C.; Ganz, Eric; Aniel, Thierry; Miniac, Arlette de.

    1982-03-01

    We consider in detail the differential cross section for polarized bremsstrahlung for angles and energies in the range of interest for a tagging system and derive a high energy, small angle approximation for this cross section. We use these approximations to determine the maxima and minima of the cross sections for these two polarization states, dσperpendicular and dσparallel, and to evaluate these cross sections at the extrema. It is shown that both dσperpendicular and dσparallel have a very sharp dip in the region of small momentum transfers. However, their behavior in the region of the dip, as a function of the azimuthal angle phi, is quite different over most of the photon spectrum. The cross section dσperpendicular behaves similarly to the cross section for unpolarized photons in that as phi increases, the sharp dip vanishes, the minimum fuses with the second maximum, and the cross section then has only a single maximum. In contrast, the sharp dip in the cross section dσparallel remains as phi increases. Coulomb corrections to the Born approximation are considered, and do not fill in these dips

  19. Quantum tagging for tags containing secret classical data

    International Nuclear Information System (INIS)

    Kent, Adrian

    2011-01-01

    Various authors have considered schemes for quantum tagging, that is, authenticating the classical location of a classical tagging device by sending and receiving quantum signals from suitably located distant sites, in an environment controlled by an adversary whose quantum information processing and transmitting power is potentially unbounded. All of the schemes proposed elsewhere in the literature assume that the adversary is able to inspect the interior of the tagging device. All of these schemes have been shown to be breakable if the adversary has unbounded predistributed entanglement. We consider here the case in which the tagging device contains a finite key string shared with distant sites but kept secret from the adversary, and show this allows the location of the tagging device to be authenticated securely and indefinitely. Our protocol relies on quantum key distribution between the tagging device and at least one distant site, and demonstrates a new practical application of quantum key distribution. It also illustrates that the attainable security in position-based cryptography can depend crucially on apparently subtle details in the security scenario considered.

  20. Introductory Raman spectroscopy

    CERN Document Server

    Ferraro, John R

    2012-01-01

    Praise for Introductory Raman Spectroscopy Highlights basic theory, which is treated in an introductory fashion Presents state-of-the-art instrumentation Discusses new applications of Raman spectroscopy in industry and research.

  1. Behavioral tagging of extinction learning.

    Science.gov (United States)

    de Carvalho Myskiw, Jociane; Benetti, Fernando; Izquierdo, Iván

    2013-01-15

    Extinction of contextual fear in rats is enhanced by exposure to a novel environment at 1-2 h before or 1 h after extinction training. This effect is antagonized by administration of protein synthesis inhibitors anisomycin and rapamycin into the hippocampus, but not into the amygdala, immediately after either novelty or extinction training, as well as by the gene expression blocker 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole administered after novelty training, but not after extinction training. Thus, this effect can be attributed to a mechanism similar to synaptic tagging, through which long-term potentiation can be enhanced by other long-term potentiations or by exposure to a novel environment in a protein synthesis-dependent fashion. Extinction learning produces a tag at the appropriate synapses, whereas novelty learning causes the synthesis of plasticity-related proteins that are captured by the tag, strengthening the synapses that generated this tag.

  2. Charge transfer in conjugated oligomers encapsulated into carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Almadori, Y.; Alvarez, L.; Michel, T.; Le Parc, R.; Bantignies, J.L.; Hermet, P.; Sauvajol, J.L. [Laboratoire Charles Coulomb UMR 5521, Universite Montpellier 2, 34095 Montpellier (France); Laboratoire Charles Coulomb UMR 5521, CNRS, 34095 Montpellier (France); Arenal, R. [Laboratoire d' Etude des Microstructures, CNRS-ONERA, 92322 Chatillon (France); Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragon, U. Zaragoza, 50018 Zaragoza (Spain); Babaa, R. [Laboratoire de Chimie des Surfaces et Interfaces, CEA, IRAMIS, SPCSI, 91191 Gif-sur-Yvette Cedex (France); Chemical Engineering Department, University of Technology PETRONAS, UTP, Ipoh-Perak (Malaysia); Jouselme, B.; Palacin, S. [Laboratoire de Chimie des Surfaces et Interfaces, CEA, IRAMIS, SPCSI, 91191 Gif-sur-Yvette Cedex (France)

    2011-11-15

    This study deals with a hybrid system consisting in quaterthiophene derivative encapsulated inside single-walled and multi-walled carbon nanotubes. Investigations of the encapsulation step are performed by transmission electron microscopy. Raman spectroscopy data point out different behaviors depending on the laser excitation energy with respect to the optical absorption of quaterthiophene. At low excitation energy (far from the oligomer resonance window) there is no significant modification of the Raman spectra before and after encapsulation. By contrast, at high excitation energy (close to the oligomer resonance window), Raman spectra exhibit a G-band shift together with an important RBM intensity loss, suggesting a significant charge transfer between the inserted molecule and the host nanotubes. Those results suggest a photo induced process leading to a significant charge transfer. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Carbon nanotube composite materials

    Science.gov (United States)

    O'Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas

    2015-03-24

    A material consisting essentially of a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes dissolved in a solvent. Un-functionalized carbon nanotube concentrations up to 30 wt % and hydroxylated carbon nanotube concentrations up to 40 wt % can be used with even small concentrations of each (less than 2 wt %) useful in producing enhanced conductivity properties of formed thin films.

  4. Strep-Tagged Protein Purification.

    Science.gov (United States)

    Maertens, Barbara; Spriestersbach, Anne; Kubicek, Jan; Schäfer, Frank

    2015-01-01

    The Strep-tag system can be used to purify recombinant proteins from any expression system. Here, protocols for lysis and affinity purification of Strep-tagged proteins from E. coli, baculovirus-infected insect cells, and transfected mammalian cells are given. Depending on the amount of Strep-tagged protein in the lysate, a protocol for batch binding and subsequent washing and eluting by gravity flow can be used. Agarose-based matrices with the coupled Strep-Tactin ligand are the resins of choice, with a binding capacity of up to 9 mg ml(-1). For purification of lower amounts of Strep-tagged proteins, the use of Strep-Tactin magnetic beads is suitable. In addition, Strep-tagged protein purification can also be automated using prepacked columns for FPLC or other liquid-handling chromatography instrumentation, but automated purification is not discussed in this protocol. The protocols described here can be regarded as an update of the Strep-Tag Protein Handbook (Qiagen, 2009). © 2015 Elsevier Inc. All rights reserved.

  5. Carbon nanotubes enhanced the lead toxicity on the freshwater fish

    International Nuclear Information System (INIS)

    Martinez, D S T; Alves, O L; Barbieri, E

    2013-01-01

    Carbon nanotubes are promising nanostructures for many applications in materials industry and biotechnology. However, it is mandatory to evaluate their toxicity and environmental implications. We evaluated nitric acid treated multiwalled carbon nanotubes (HNO 3 -MWCNT) toxicity in Nile tilapia (Oreochromis niloticus) and also the lead (Pb) toxicity modulation after the nanotube interaction. Industrial grade multiwalled carbon nanotubes [Ctube 100, CNT Co. Ltd] were treated with 9M HNO 3 for 12h at 150°C to generate oxygenated groups on the nanotube surface, to improve water dispersion and heavy metal interaction. The HNO 3 -treated multiwalled carbon nanotubes were physico-chemically characterized by several techniques [e.g. TEM, FE-SEM, TGA, ζ-potential and Raman spectroscopy]. HNO 3 -MWCNT did not show toxicity on Nile tilapia when the concentration ranged from 0.1 to 3.0 mg/L, and the maximum exposure time was 96h. After 24, 48, 72 and 96h the LC50 values of Pb were 1.65, 1.32, 1.10 and 0.99 mg/L, respectively. To evaluate the Pb-nanotube interaction influence on the ecotoxicity, we submitted the Nile tilapia to different concentrations of Pb mixed with a non-toxic concentration of HNO 3 -MWCNT (1.0 mg/L). After 24, 48, 72, 96 h the LC50 values of Pb plus nanotubes were: 0.32, 0.25, 0.20, 0.18 mg/L, respectively. These values showed a synergistic effect after Pb-nanotube interaction since Pb toxicity increased over five times. X-ray energy dispersive spectroscopy (EDS) was used to confirm lead adsorption on the carbon nanotube oxidized surface. The exposure of Nile tilapia to Pb plus HNO 3 -MWCNT caused both oxygen consumption and ammonium excretion decrease, when compared to the control. Finally, our results show that carbon nanotubes interact with classical pollutants drawing attention to the environmental implications.

  6. Fabrication and characterization of nanocomposites reinforced by carbon nanotubes - (1) synthesis of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Hseuh Hsiangming; Tai Nyanhwa; Perng Tongping [Dept. of Material Science, National Tsing-Hwa Univ., TW (China); Chyou Sander [Taiwan Power Research Inst., Taiwan Power Co., Taipei (China)

    2003-07-01

    Multi-walled carbon nanotubes (MWCNTs) produced by floating catalyst method were used for reinforcing material in polymeric nanocomposites. Five different kinds of carbon sources (benzene, toluene, xylene, cyclo-hexane, n-hexane) were used as precursors in the thermal chemical vapor deposition process. The products were collected and examined by Raman, HRTEM, and FESEM. The differences in microstructure and morphologies among these products are analyzed and discussed. (orig.)

  7. Raman spectroscopy insight into Norovirus encapsulation in Bombyx mori cypovirus cubic microcrystals.

    Science.gov (United States)

    Mori, Hajime; Oda, Naoki; Abe, Satoshi; Ueno, Takafumi; Zhu, Wenliang; Pernstich, Chris; Pezzotti, Giuseppe

    2018-05-16

    Protein and amino acid structures of Norovirus-like particles (NoVLP) have been investigated by Raman spectroscopy before and after encapsulation into Bombyx mori cypovirus (BmCPV) cubic microcrystals, which are usually referred to as cubes or polyhedra. Two different types of tag were used in co-expression, namely VP3 and H1 tags. VP3 tag is derived from a capsid protein VP4 from BmCPV and H1 tag is N-terminal α-helix of BmCPV polyhedrin, respectively. A major capsid protein VP1 of NoVLP G11.4 was fused with H1 or VP3 tags, and then encapsulated into BmCPV polyhedra. Analyses of the spectroscopic data permitted the assignment of conformation-sensitive Raman bands to viral amino acid constituents and the observation of structural similarities or differences between differently tagged samples. Three separate Raman zones were attentioned, namely, the ring-mode structure region (1000-1500 cm -1 ), the CO and CC double-bond region and its surroundings (1500-1750 cm -1 ), and the high-frequency CH stretching region (2800-3100 cm -1 ). Structural fingerprints could be found in specific spectral zones for differently co-expressed samples. One clear characteristic of the H1-tagged VP1 polyhedra was the increase in tyrosine fraction, which played a critical role in binding neighboring strands through its unpaired negatively charged COO - sites. This feature could consistently be detected in different regions, but it was best represented by Raman signals associated with negatively charged COO - sites and H1 helices in the double-bond region. Such peculiar chemical features were revealed by two relatively broad bands at 1570 and 1630 cm -1 , which were assigned to COO - anti-symmetric stretching and amide I in 3 10 -helix extensions to α-helices at N-termini, respectively. These specific features did not display in the spectrum of the VP3-tagged VP1 polyhedra. Concurrently, a strong reduction of CH bond Raman signal was noticed in the high frequency stretching

  8. Editorial Tag Endogeneity for News Websites

    OpenAIRE

    Bruno Ribeiro; Ricardo Morla; Amílcar Correia

    2013-01-01

    Editors and journalists at some news websites label their articles with structure and content-related editorial tags. Each article can have more than one tag and each tag can be used in more than one article. A network of tags can be defined whose edges are all possible pairs of tags in each article. Because editorial tags relate to structure and content rather than individual articles, the analysis of a network of editorial tags could assist editorial decisions to prioritize types of content...

  9. Tempting To Tag: An Experimental Comparison Of Four Tagging Input Mechanisms

    Directory of Open Access Journals (Sweden)

    Mark Melenhorst

    2010-01-01

    Full Text Available Tagging helps achieve improved indexing and recommendation of resources (e.g., videos or pictures in large data collections. In order to reap the benefits of tagging, people must be persuaded to label the resources they consume. This paper reports on a study in which four different tagging input mechanisms and their effect on users' motivation to tag were compared. The mechanisms consisted of a standard tag input box, a chatbot-like environment, a bookmarking mechanism, and a "tag and vote" game. The results of our experiment show that the use of the nonstandard tagging input mechanisms does not affect users' motivation to tag. In some instances tagging mechanisms were found to distract users from their primary task: consuming resources. Persuading people to tag might be accomplished more effectively by using other motivating tagging mechanisms (e.g., tagging games, or motivation could be created by explaining the usefulness of tagging.

  10. Tagging the European eel Anguilla anguilla (L.) with coded wire tags

    DEFF Research Database (Denmark)

    Thomassen, S.; Pedersen, Michael Ingemann; Holdensgaard, G.

    2000-01-01

    The coded wire tag (CWT) system was examined as a possible tool for tagging European eels (Anguilla anguilla). Two size groups of eels (3.8 and 10.2 g) were tagged with CWTs in the dorsal musculature, Tag loss 28 days after tagging was 3.1% for the small and 0.7% for the large groups of eels...

  11. Large-scale aligned silicon carbonitride nanotube arrays: Synthesis, characterization, and field emission property

    International Nuclear Information System (INIS)

    Liao, L.; Xu, Z.; Liu, K. H.; Wang, W. L.; Liu, S.; Bai, X. D.; Wang, E. G.; Li, J. C.; Liu, C.

    2007-01-01

    Large-scale aligned silicon carbonitride (SiCN) nanotube arrays have been synthesized by microwave-plasma-assisted chemical vapor deposition using SiH 4 , CH 4 , and N 2 as precursors. The three elements of Si, C, and N are chemically bonded with each other and the nanotube composition can be adjusted by varying the SiH 4 concentration, as revealed by electron energy loss spectroscopy and x-ray photoelectron spectroscopy. The evolution of microstructure of the SiCN nanotubes with different Si concentrations was characterized by high-resolution transmission electron microscopy and Raman spectroscopy. The dependence of field emission characteristics of the SiCN nanotubes on the composition has been investigated. With the increasing Si concentration, the SiCN nanotube exhibits more favorable oxidation resistance, which suggests that SiCN nanotube is a promising candidate as stable field emitter

  12. Tagging, Encoding, and Jones Optimality

    DEFF Research Database (Denmark)

    Danvy, Olivier; Lopez, Pablo E. Martinez

    2003-01-01

    A partial evaluator is said to be Jones-optimal if the result of specializing a self-interpreter with respect to a source program is textually identical to the source program, modulo renaming. Jones optimality has already been obtained if the self-interpreter is untyped. If the selfinterpreter...... is typed, however, residual programs are cluttered with type tags. To obtain the original source program, these tags must be removed. A number of sophisticated solutions have already been proposed. We observe, however, that with a simple representation shift, ordinary partial evaluation is already Jones......-optimal, modulo an encoding. The representation shift amounts to reading the type tags as constructors for higherorder abstract syntax. We substantiate our observation by considering a typed self-interpreter whose input syntax is higher-order. Specializing this interpreter with respect to a source program yields...

  13. Tagging, Encoding, and Jones Optimality

    DEFF Research Database (Denmark)

    Danvy, Olivier; López, Pablo Ernesto Martínes

    2003-01-01

    A partial evaluator is said to be Jones-optimal if the result of specializing a self-interpreter with respect to a source program is textually identical to the source program, modulo renaming. Jones optimality has already been obtained if the self-interpreter is untyped. If the selfinterpreter...... is typed, however, residual programs are cluttered with type tags. To obtain the original source program, these tags must be removed. A number of sophisticated solutions have already been proposed. We observe, however, that with a simple representation shift, ordinary partial evaluation is already Jones...

  14. WebTag: Web browsing into sensor tags over NFC.

    Science.gov (United States)

    Echevarria, Juan Jose; Ruiz-de-Garibay, Jonathan; Legarda, Jon; Alvarez, Maite; Ayerbe, Ana; Vazquez, Juan Ignacio

    2012-01-01

    Information and Communication Technologies (ICTs) continue to overcome many of the challenges related to wireless sensor monitoring, such as for example the design of smarter embedded processors, the improvement of the network architectures, the development of efficient communication protocols or the maximization of the life cycle autonomy. This work tries to improve the communication link of the data transmission in wireless sensor monitoring. The upstream communication link is usually based on standard IP technologies, but the downstream side is always masked with the proprietary protocols used for the wireless link (like ZigBee, Bluetooth, RFID, etc.). This work presents a novel solution (WebTag) for a direct IP based access to a sensor tag over the Near Field Communication (NFC) technology for secure applications. WebTag allows a direct web access to the sensor tag by means of a standard web browser, it reads the sensor data, configures the sampling rate and implements IP based security policies. It is, definitely, a new step towards the evolution of the Internet of Things paradigm.

  15. Confocal Raman Microscopy

    CERN Document Server

    Dieing, Thomas; Toporski, Jan

    2011-01-01

    Confocal Raman Microscopy is a relatively new technique that allows chemical imaging without specific sample preparation. By integrating a sensitive Raman spectrometer within a state-of-the-art microscope, Raman microscopy with a spatial resolution down to 200nm laterally and 500nm vertically can be achieved using visible light excitation. Recent developments in detector and computer technology as well as optimized instrument design have reduced integration times of Raman spectra by orders of magnitude, so that complete images consisting of tens of thousands of Raman spectra can be acquired in seconds or minutes rather than hours, which used to be standard just one decade ago. The purpose of this book is to provide the reader a comprehensive overview of the rapidly developing field of Confocal Raman Microscopy and its applications.

  16. Tempting to Tag : An Experimental Comparison of Four Tagging Input Mechanisms

    OpenAIRE

    Melenhorst, Mark; van Velsen, Lex

    2010-01-01

    Tagging helps achieve improved indexing and recommendation of resources (e.g., videos or pictures) in large data collections. In order to reap the benefits of tagging, people must be persuaded to label the resources they consume. This paper reports on a study in which four different tagging input mechanisms and their effect on users' motivation to tag were compared. The mechanisms consisted of a standard tag input box, a chatbot-like environment, a bookmarking mechanism, and a "tag and v...

  17. Chirality Characterization of Dispersed Single Wall Carbon Nanotubes

    Science.gov (United States)

    Namkung, Min; Williams, Phillip A.; Mayweather, Candis D.; Wincheski, Buzz; Park, Cheol; Namkung, Juock S.

    2005-01-01

    Raman scattering and optical absorption spectroscopy are used for the chirality characterization of HiPco single wall carbon nanotubes (SWNTs) dispersed in aqueous solution with the surfactant sodium dodecylbenzene sulfonate. Radial breathing mode (RBM) Raman peaks for semiconducting and metallic SWNTs are identified by directly comparing the Raman spectra with the Kataura plot. The SWNT diameters are calculated from these resonant peak positions. Next, a list of (n, m) pairs, yielding the SWNT diameters within a few percent of that obtained from each resonant peak position, is established. The interband transition energies for the list of SWNT (n, m) pairs are calculated based on the tight binding energy expression for each list of the (n, m) pairs, and the pairs yielding the closest values to the corresponding experimental optical absorption peaks are selected. The results reveal that (1, 11), (4, 11), and (0, 11) as the most probable chiralities of the semiconducting nanotubes. The results also reveal that (4, 16), (6, 12) and (8, 8) are the most probable chiralities for the metallic nanotubes. Directly relating the Raman scattering data to the optical absorption spectra, the present method is considered the simplest technique currently available. Another advantage of this technique is the use of the E(sup 8)(sub 11) peaks in the optical absorption spectrum in the analysis to enhance the accuracy in the results.

  18. Homogeneous CdTe quantum dots-carbon nanotubes heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, Kayo Oliveira [Grupo de Pesquisa em Química de Materiais – (GPQM), Departamento de Ciências Naturais, Universidade Federal de São João del-Rei, Campus Dom Bosco, Praça Dom Helvécio, 74, CEP 36301-160, São João del-Rei, MG (Brazil); Bettini, Jefferson [Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, CEP 13083-970, Campinas, SP (Brazil); Ferrari, Jefferson Luis [Grupo de Pesquisa em Química de Materiais – (GPQM), Departamento de Ciências Naturais, Universidade Federal de São João del-Rei, Campus Dom Bosco, Praça Dom Helvécio, 74, CEP 36301-160, São João del-Rei, MG (Brazil); Schiavon, Marco Antonio, E-mail: schiavon@ufsj.edu.br [Grupo de Pesquisa em Química de Materiais – (GPQM), Departamento de Ciências Naturais, Universidade Federal de São João del-Rei, Campus Dom Bosco, Praça Dom Helvécio, 74, CEP 36301-160, São João del-Rei, MG (Brazil)

    2015-01-15

    The development of homogeneous CdTe quantum dots-carbon nanotubes heterostructures based on electrostatic interactions has been investigated. We report a simple and reproducible non-covalent functionalization route that can be accomplished at room temperature, to prepare colloidal composites consisting of CdTe nanocrystals deposited onto multi-walled carbon nanotubes (MWCNTs) functionalized with a thin layer of polyelectrolytes by layer-by-layer technique. Specifically, physical adsorption of polyelectrolytes such as poly (4-styrene sulfonate) and poly (diallyldimethylammonium chloride) was used to deagglomerate and disperse MWCNTs, onto which we deposited CdTe quantum dots coated with mercaptopropionic acid (MPA), as surface ligand, via electrostatic interactions. Confirmation of the CdTe quantum dots/carbon nanotubes heterostructures was done by transmission and scanning electron microscopies (TEM and SEM), dynamic-light scattering (DLS) together with absorption, emission, Raman and infrared spectroscopies (UV–vis, PL, Raman and FT-IR). Almost complete quenching of the PL band of the CdTe quantum dots was observed after adsorption on the MWCNTs, presumably through efficient energy transfer process from photoexcited CdTe to MWCNTs. - Highlights: • Highly homogeneous CdTe-carbon nanotubes heterostructures were prepared. • Simple and reproducible non-covalent functionalization route. • CdTe nanocrystals homogeneously deposited onto multi-walled carbon nanotubes. • Efficient energy transfer process from photoexcited CdTe to MWCNTs.

  19. A Comparative Study of Carbon Nanotubes Synthesized from Co/Zn/Al and Fe/Ni/Al Catalyst

    Directory of Open Access Journals (Sweden)

    Ezekiel Dixon Dikio

    2011-01-01

    Full Text Available The catalyst systems Fe/Ni/Al and Co/Zn/Al were synthesized and used in the synthesis of carbon nanotubes. The carbon nanotubes produced were characterized by Field Emission Scanning Electron Microscope (FE-SEM, Energy Dispersive x-ray Spectroscopy (EDS, Raman spectroscopy, Thermogravimetric Analysis (TGA and Transmission Electron Microscope (TEM. A comparison of the morphological profile of the carbon nanotubes produced from these catalysts indicates the catalyst system Fe/Ni/Al to have produced higher quality carbon nanotubes than the catalyst system Co/Zn/Al.

  20. Solid-State Spun Fibers from 1 mm Long Carbon Nanotube Forests Synthesized by Water-Assisted Chemical Vapor Deposition

    Science.gov (United States)

    Zhang, Shanju; Zhu, Lingbo; Minus, Marilyn L.; Chae, han Gi; Jagannathan, Sudhakar; Wong, Ching-Ping; Kowalik, Janusz; Roberson, Luke B.; Kumar, Satish

    2007-01-01

    In this work, we report continuous carbon nanotube fibers dry-drawn directly from water-assisted CVD grown forests with millimeter scale length. As-drawn nanotube fibers exist as aerogel and can be transformed into more compact fibers through twisting or densification with a volatile liquid. Nanotube fibers are characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman microscopy and wide-angle X-ray diffraction (WAXD). Mechanical behavior and electrical conductivity of the post-treated nanotube fibers are investigated.

  1. Resonant ablation of single-wall carbon nanotubes by femtosecond laser pulses

    International Nuclear Information System (INIS)

    Arutyunyan, N R; Komlenok, M S; Kononenko, V V; Pashinin, V P; Pozharov, A S; Konov, V I; Obraztsova, E D

    2015-01-01

    The thin 50 nm film of bundled arc-discharge single-wall carbon nanotubes was irradiated by femtosecond laser pulses with wavelengths 675, 1350 and 1745 nm corresponding to the absorption band of metallic nanotubes E 11 M , to the background absorption and to the absorption band of semiconducting nanotubes E 11 S , respectively. The aim was to induce a selective removal of nanotubes of specific type from the bundled material. Similar to conducted thermal heating experiments, the effect of laser irradiation results in suppression of all radial breathing modes in the Raman spectra, with preferential destruction of the metallic nanotubes with diameters less than 1.26 nm and of the semiconducting nanotubes with diameters 1.36 nm. However, the etching rate of different nanotubes depends on the wavelength of the laser irradiation. It is demonstrated that the relative content of nanotubes of different chiralities can be tuned by a resonant laser ablation of undesired nanotube fraction. The preferential etching of the resonant nanotubes has been shown for laser wavelengths 675 nm (E 11 M ) and 1745 nm (E 11 S ). (paper)

  2. Nanotubes and nanowires

    Indian Academy of Sciences (India)

    Unknown

    junction nanotubes by the pyrolysis of appropriate organic precursors. ... By making use of carbon nanotubes, nanowires of metals, metal ..... The use of activated carbon in place of ..... required for the complete removal of the carbon template.

  3. Carbon nanotube nanoelectrode arrays

    Science.gov (United States)

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

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

  4. Multiwalled Carbon Nanotubes Decorated with Cobalt Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    D. G. Larrude

    2012-01-01

    Full Text Available Multiwalled carbon nanotubes (MWCNTs synthesized by spray pyrolysis were decorated with cobalt oxide nanoparticles using a simple synthesis route. This wet chemistry method yielded nanoparticles randomly anchored to the surface of the nanotubes by decomposition of cobalt nitrate hexahydrate diluted in acetone. Electron microscopy analysis indicated that dispersed particles were formed on the MWCNTs walls. The average size increased with the increasing concentration of cobalt nitrate in acetone in the precursor mixture. TEM images indicated that nanoparticles were strongly attached to the tube walls. The Raman spectroscopy results suggested that the MWCNT structure was slightly damaged after the nanoparticle growth.

  5. Ionic Liquid for in situ Vis/NIR and Raman Spectroelectrochemistry: Doping of Carbon Nanostructures

    Czech Academy of Sciences Publication Activity Database

    Kavan, Ladislav; Dunsch, L.

    2003-01-01

    Roč. 4, - (2003), s. 944-950 ISSN 1439-4235 R&D Projects: GA AV ČR IAA4040306 Institutional research plan: CEZ:AV0Z4040901 Keywords : ionic liquids * nanotubes * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 3.316, year: 2003

  6. Atomic force and shear force based tip-enhanced Raman spectroscopy and imaging

    NARCIS (Netherlands)

    Kharintsev, S.S.; Hoffmann, G.G.; Dorozhkin, P.S.; With, de G.; Loos, J.

    2007-01-01

    Underlying near-field optibal effects on the nanoscale have stimulated the development of apertureless vibrational spectroscopy and imaging with ultrahigh spatial resolution. We demonstrate tip-enhanced Raman spectra of single-walled carbon nanotubes (SWCNTs), recorded with a scanning near-field

  7. Satellite Tags- Guam/CNMI EEZ

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Satellite tagging was implemented in 2013. Satellite tagging is conducted using a Dan Inject air rifle and deployment arrows designed by Wildlife Computers. Two...

  8. HMSRP Hawaiian Monk Seal Tag Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains records for all tags applied to Hawaiian monk seals since 1981. These tags were applied by PSD personnel and cooperating scientists as part of...

  9. Optical properties of carbon nanotubes

    Science.gov (United States)

    Chen, Gugang

    This thesis addresses the optical properties of novel carbon filamentary nanomaterials: single-walled carbon nanotubes (SWNTs), double-walled carbon nanotubes (DWNTs), and SWNTs with interior C60 molecules ("peapods"). Optical reflectance spectra of bundled SWNTs are discussed in terms of their electronic energy band structure. An Effective Medium Model for a composite material was found to provide a reasonable description of the spectra. Furthermore, we have learned from optical absorption studies of DWNTs and C60-peapods that the host tube and the encapsulant interact weakly; small shifts in interband absorption structure were observed. Resonant Raman scattering studies on SWNTs synthesized via the HiPCO process show that the "zone-folding" approximation for phonons and electrons works reasonably well, even for small diameter (d effect, rather than the vdW interaction. Finally, we studied the chemical doping of DWNTs, where the dopant (Br anions) is chemically bound to the outside of the outer tube. The doped DWNT system is a model for a cylindrical molecular capacitor. We found experimentally that 90% of the positive charge resides on the outer tube, so that most of electric field on the inner tube is screened, i.e., we have observed a molecular Faraday cage effect. A self-consistent theoretical model in the tight-binding approximation with a classical electrostatic energy term is in good agreement with our experimental results.

  10. Raman spectroscopy in graphene

    International Nuclear Information System (INIS)

    Malard, L.M.; Pimenta, M.A.; Dresselhaus, G.; Dresselhaus, M.S.

    2009-01-01

    Recent Raman scattering studies in different types of graphene samples are reviewed here. We first discuss the first-order and the double resonance Raman scattering mechanisms in graphene, which give rise to the most prominent Raman features. The determination of the number of layers in few-layer graphene is discussed, giving special emphasis to the possibility of using Raman spectroscopy to distinguish a monolayer from few-layer graphene stacked in the Bernal (AB) configuration. Different types of graphene samples produced both by exfoliation and using epitaxial methods are described and their Raman spectra are compared with those of 3D crystalline graphite and turbostratic graphite, in which the layers are stacked with rotational disorder. We show that Resonance Raman studies, where the energy of the excitation laser line can be tuned continuously, can be used to probe electrons and phonons near the Dirac point of graphene and, in particular allowing a determination to be made of the tight-binding parameters for bilayer graphene. The special process of electron-phonon interaction that renormalizes the phonon energy giving rise to the Kohn anomaly is discussed, and is illustrated by gated experiments where the position of the Fermi level can be changed experimentally. Finally, we discuss the ability of distinguishing armchair and zig-zag edges by Raman spectroscopy and studies in graphene nanoribbons in which the Raman signal is enhanced due to resonance with singularities in the density of electronic states.

  11. Raman fiber lasers

    CERN Document Server

    2017-01-01

    This book serves as a comprehensive, up-to-date reference about this cutting-edge laser technology and its many new and interesting developments. Various aspects and trends of Raman fiber lasers are described in detail by experts in their fields. Raman fiber lasers have progressed quickly in the past decade, and have emerged as a versatile laser technology for generating high power light sources covering a spectral range from visible to mid-infrared. The technology is already being applied in the fields of telecommunication, astronomy, cold atom physics, laser spectroscopy, environmental sensing, and laser medicine. This book covers various topics relating to Raman fiber laser research, including power scaling, cladding and diode pumping, cascade Raman shifting, single frequency operation and power amplification, mid-infrared laser generation, specialty optical fibers, and random distributed feedback Raman fiber lasers. The book will appeal to scientists, students, and technicians seeking to understand the re...

  12. Effect of Steam-Treatment Time on the Length and Structure of Single-Walled and Double-Walled Carbon Nanotubes

    Czech Academy of Sciences Publication Activity Database

    Kierkowicz, M.; Pach, E.; Santidrian, Ana; Tobias-Rossell, E.; Kalbáč, Martin; Ballesteros, B.; Tobias, G.

    2016-01-01

    Roč. 2, č. 2 (2016), s. 108-116 E-ISSN 2199-692X R&D Projects: GA MŠk LL1301 Institutional support: RVO:61388955 Keywords : carbon nanotubes * Raman spectroelectrochemistry * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 2.937, year: 2016

  13. Microwave-induced electrophilic addition of single-walled carbon nanotubes with alkylhalides

    Energy Technology Data Exchange (ETDEWEB)

    Xu Yang [Faculty of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Wang Xianbao [Faculty of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Ministry-of-Education, Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Hubei University, Wuhan 430062 (China)], E-mail: wxb@hubu.edu.cn; Tian Rong; Li Shaoqing; Wan Li; Li Mingjian; You Haijun; Li Qin [Faculty of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Wang Shimin [Faculty of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Ministry-of-Education, Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Hubei University, Wuhan 430062 (China)

    2008-02-15

    We report the microwave-induced electrophilic addition of single-walled carbon nanotubes (SWNTs) with alkylhalides using Lewis acid as a catalyst followed by hydrolysis. The reaction results in the attachment of alkyl and hydroxyl groups to the surface of the nanotubes. This rapid and high-energy microwave radiation is found to be highly efficient for this reaction, which only needs as low as several minutes. The resulting nanotubes were characterized with FTIR, UV-vis-NIR, Raman, TGA, TEM and AFM. It demonstrates that iodo-alkanes show higher reaction activity with SWNTs than chloro- and bromo-alkanes.

  14. The growth of aligned carbon nanotubes on quartz substrate by spray pyrolysis of hexane

    International Nuclear Information System (INIS)

    Sadeghian, Zahra

    2008-01-01

    Vertically aligned multiwall carbon nanotubes were grown by spray pyrolysis of hexane as the carbon source in the presence of ferrocene as catalyst precursor on a quartz substrate. In recent work we used optimal experimental parameters for the feeding method, reactor conditions, reaction temperature and time, concentration of catalyst and flow rate of feed and gas. The process parameters were chosen so as to obtain multiwall carbon nanotubes and aligned multiwall carbon nanotubes. The tubes are around 15-80 nm in diameter. The morphology and structure of the samples were characterized by x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy analyses

  15. Multi-walled carbon nanotubes (MWCNTs) functionalized with amino groups by reacting with supercritical ammonia fluids

    International Nuclear Information System (INIS)

    Shao Lu; Bai Yongping; Huang Xu; Gao Zhangfei; Meng Linghui; Huang Yudong; Ma Jun

    2009-01-01

    For the first time, supercritical ammonia fluid was utilized to simply functionalize multi-walled carbon nanotube (MWCNT) with amino groups. The successful amino functionalization of MWCNTs was proven and the physicochemical properties of MWCNTs before and after supercritical ammonia fluids modifications were characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscope (AFM) and Raman spectroscopy. The results also indicated that the supercritical ammonia fluids had the visible effects on the nanostructure of carbon nanotubes. Our novel modification approach provides an easy way to modify MWCNTs with amino groups, which is very useful for realizing 'carbon nanotube economy' in the near future.

  16. Optical absorption and thermal transport of individual suspended carbon nanotube bundles.

    Science.gov (United States)

    Hsu, I-Kai; Pettes, Michael T; Bushmaker, Adam; Aykol, Mehmet; Shi, Li; Cronin, Stephen B

    2009-02-01

    A focused laser beam is used to heat individual single-walled carbon nanotube bundles bridging two suspended microthermometers. By measurement of the temperature rise of the two thermometers, the optical absorption of 7.4-10.3 nm diameter bundles is found to be between 0.03 and 0.44% of the incident photons in the 0.4 microm diameter laser spot. The thermal conductance of the bundle is obtained with the additional measurement of the temperature rise of the nanotubes in the laser spot from shifts in the Raman G band frequency. According to the nanotube bundle diameter determined by transmission electron microscopy, the thermal conductivity is obtained.

  17. ATLAS boosted object tagging 2

    CERN Document Server

    Caudron, Julien; The ATLAS collaboration

    2015-01-01

    A detailed study into the optimal techniques for identifying boosted hadronically decaying W or Z bosons is presented. Various algorithms for reconstructing, grooming and tagging bosonic jets are compared for W bosons with a wide range of transverse momenta using 8 TeV data and 8 TeV and 13 TeV MC simulations. In addition, given that a hadronic jet has been identified as resulting from the hadronic decay of a W or Z, a technique is developed to discriminate between W and Z bosons. The modeling of the tagging variables used in this technique is studied using 8 TeV pp collision data and systematic uncertainties for the tagger efficiency and fake rates are evaluated.

  18. Selective and Scalable Chemical Removal of Thin Single-Walled Carbon Nanotubes from their Mixtures with Double-Walled Carbon Nanotubes

    Czech Academy of Sciences Publication Activity Database

    Komínková, Zuzana; Valeš, Václav; Kalbáč, Martin

    2015-01-01

    Roč. 21, č. 45 (2015), s. 16147 ISSN 1521-3765 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388955 Keywords : carbon nanotubes * electrochemical doping * in-situ Raman spectroelectrochemistry Subject RIV: CG - Electrochemistry

  19. Predicting floods with Flickr tags.

    Science.gov (United States)

    Tkachenko, Nataliya; Jarvis, Stephen; Procter, Rob

    2017-01-01

    Increasingly, user generated content (UGC) in social media postings and their associated metadata such as time and location stamps are being used to provide useful operational information during natural hazard events such as hurricanes, storms and floods. The main advantage of these new sources of data are twofold. First, in a purely additive sense, they can provide much denser geographical coverage of the hazard as compared to traditional sensor networks. Second, they provide what physical sensors are not able to do: By documenting personal observations and experiences, they directly record the impact of a hazard on the human environment. For this reason interpretation of the content (e.g., hashtags, images, text, emojis, etc) and metadata (e.g., keywords, tags, geolocation) have been a focus of much research into social media analytics. However, as choices of semantic tags in the current methods are usually reduced to the exact name or type of the event (e.g., hashtags '#Sandy' or '#flooding'), the main limitation of such approaches remains their mere nowcasting capacity. In this study we make use of polysemous tags of images posted during several recent flood events and demonstrate how such volunteered geographic data can be used to provide early warning of an event before its outbreak.

  20. Approximation properties of haplotype tagging

    Directory of Open Access Journals (Sweden)

    Dreiseitl Stephan

    2006-01-01

    Full Text Available Abstract Background Single nucleotide polymorphisms (SNPs are locations at which the genomic sequences of population members differ. Since these differences are known to follow patterns, disease association studies are facilitated by identifying SNPs that allow the unique identification of such patterns. This process, known as haplotype tagging, is formulated as a combinatorial optimization problem and analyzed in terms of complexity and approximation properties. Results It is shown that the tagging problem is NP-hard but approximable within 1 + ln((n2 - n/2 for n haplotypes but not approximable within (1 - ε ln(n/2 for any ε > 0 unless NP ⊂ DTIME(nlog log n. A simple, very easily implementable algorithm that exhibits the above upper bound on solution quality is presented. This algorithm has running time O((2m - p + 1 ≤ O(m(n2 - n/2 where p ≤ min(n, m for n haplotypes of size m. As we show that the approximation bound is asymptotically tight, the algorithm presented is optimal with respect to this asymptotic bound. Conclusion The haplotype tagging problem is hard, but approachable with a fast, practical, and surprisingly simple algorithm that cannot be significantly improved upon on a single processor machine. Hence, significant improvement in computatational efforts expended can only be expected if the computational effort is distributed and done in parallel.

  1. b-tagging in DELPHI at LEP

    CERN Document Server

    Abdallah, J; Adam, W; Adye, T; Adzic, P; Albrecht, T; Alderweireld, T; Alemany-Fernandez, R; Allmendinger, T; Allport, P P; Almehed, S; Amaldi, Ugo; Amapane, N; Amato, S; Anashkin, E; Andreazza, A; Andringa, S; Anjos, N; Antilogus, P; Apel, W D; Arnoud, Y; Ask, S; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Ballestrero, A; Bambade, P; Barbier, R; Bardin, Dimitri Yuri; Barker, G; Baroncelli, A; Bates, M; Battaglia, Marco; Baubillier, M; Becks, K H; Begalli, M; Behrmann, A; Benekos, N C; Benvenuti, Alberto C; Bérat, C; Berggren, M; Berntzon, L; Bertrand, D; Besançon, M; Besson, N; Bibby, J; Biffi, P; Bloch, D; Blom, M; Bonesini, M; Boonekamp, M; Booth, P S L; Borisov, G; Botner, O; Bouquet, B; Bowcock, T J V; Boyko, I; Bracko, M; Branchini, P; Brenner, R; Brodet, E; Brückman, P; Brunet, J M; Bugge, L; Buschmann, P; Caccia, M; Calvi, M; Camporesi, T; Canale, V; Carena, F; Castro, N; Cavallo, F R; Chabaud, V; Chapkin, M M; Charpentier, P; Checchia, P; Chierici, R; Shlyapnikov, P; Chudoba, J; Chung, S U; Cieslik, K; Collins, P; Contri, R; Cosme, G; Cossutti, F; Costa, M J; Couchot, F; Crawley, B; Crennell, D J; Cuevas-Maestro, J; D'Almagne, B; D'Hondt, J; Dalmau, J; Da Silva, T; Da Silva, W; Della Ricca, G; De Angelis, A; de Boer, Wim; De Clercq, C; De Lotto, B; De Maria, N; De Min, A; De Paula, L S; Di Ciaccio, Lucia; Dijkstra, H; Di Simone, A; Doroba, K; Drees, J; Dris, M; Eigen, G; Ekelöf, T J C; Ellert, M; Elsing, M; Espirito-Santo, M C; Fanourakis, G K; Fassouliotis, D; Feindt, M; Fernández, J; Ferrer, A; Ferro, F; Flagmeyer, U; Föth, H; Fokitis, E; Fulda-Quenzer, F; Fuster, J A; Gandelman, M; García, C; Gavillet, P; Gazis, E N; Geralis, T; Gokieli, R; Golob, B; Gómez-Cadenas, J J; Gómez-Ceballos, G; Gonçalves, P; Graziani, E; Grosdidier, G; Grzelak, K; Guy, J; Haag, C; Hallgren, A; Hamacher, K; Hamilton, K; Hansen, J; Haug, S; Hauler, F; Hedberg, V; Hennecke, M; Hernando, J A; Herr, H; Heuser, J M; Holmgren, S O; Holt, P J; Houlden, M A; Hultqvist, K; Jackson, J N; Jalocha, P; Jarlskog, C; Jarlskog, G; Jarry, P; Jeans, D; Johansson, E K; Johansson, P D; Jonsson, P; Joram, C; Jungermann, L; Kapusta, F; Karlsson, M; Katsanevas, S; Katsoufis, E C; Keränen, R; Kernel, G; Kersevan, Borut P; Kiiskinen, A P; King, B T; Kjaer, N J; Kluit, P; Kokkinias, P; Kourkoumelis, C; Kuznetsov, O; Krumshtein, Z; Kucharczyk, M; Kucewicz, W; Kurowska, J; Lamsa, J; Leder, G; Ledroit, F; Leinonen, L; Leitner, R; Lemonne, J; Lepeltier, V; Lesiak, T; Liebig, W; Liko, D; Lipniacka, A; Lopes, J H; López, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J; Malek, A; Maltezos, S; Mandl, F; Marco, J; Marco, R; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Martínez-Vidal, F; Masik, J; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Mazzucato, F; Mazzucato, M; McNulty, R; Meroni, C; Meyer, W T; Migliore, E; Mitaroff, W A; Mjörnmark, U; Moa, T; Moch, M; Mönig, K; Monge, R; Montenegro, J; Moraes, D; Moreno, S; Morettini, P; Müller, U; Münich, K; Mulders, M; Mundim, L; Murray, W; Muryn, B; Myatt, Gerald; Myklebust, T; Nassiakou, M; Navarria, Francesco Luigi; Nawrocki, K; Nicolaidou, R; Niezurawski, P; Nikolenko, M; Nomerotski, A; Norman, A; Nygren, A; Oblakowska-Mucha, A; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Österberg, K; Ouraou, A; Oyanguren, A; Paganoni, M; Paiano, S; Palacios, J P; Palka, H; Papadopoulou, T D; Pape, L; Parkes, C; Parodi, F; Parzefall, U; Passeri, A; Passon, O; Peralta, L; Perepelitsa, V F; Perrotta, A; Petrolini, A; Piedra, J; Pieri, L; Pierre, F; Pimenta, M; Piotto, E; Podobnik, T; Poireau, V; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Pukhaeva, N; Pullia, Antonio; Rames, J; Ramler, L; Read, A; Rebecchi, P; Rehn, J; Reid, D; Reinhardt, R; Renton, P B; Richard, F; Rídky, J; Rivero, M; Rodríguez, D; Romero, A; Ronchese, P; Rosenberg, E I; Roudeau, Patrick; Rovelli, T; Ruhlmann-Kleider, V; Ryabtchikov, D; Sadovskii, A; Salmi, L; Salt, J; Savoy-Navarro, A; Schwickerath, U; Segar, A; Sekulin, R L; Siebel, M; Sissakian, A N; Smadja, G; Smirnova, O G; Sokolov, A; Sopczak, A; Sosnowski, R; Spassoff, Tz; Stanitzki, M; Stavitski, I; Stocchi, A; Strauss, J; Stugu, B; Szczekowski, M; Szeptycka, M; Szumlak, T; Tabarelli de Fatis, T; Taffard, A C; Tegenfeldt, F; Timmermans, J; Tinti, N; Tkatchev, L G; Tobin, M; Todorovova, S; Tomaradze, A G; Tomé, B; Tonazzo, A; Tortosa, P; Travnicek, P; Treille, D; Trischuk, W; Tristram, G; Trochimczuk, M; Troncon, C; Turluer, M L; Tyapkin, I A; Tyapkin, P; Tyndel, M; Tzamarias, S; Uvarov, V; Valenti, G; van Dam, P; Van Eldik, J; Van Lysebetten, A; Van Remortel, N; Van Vulpen, I B; Vegni, G; Veloso, F; Venus, W A; Verbeure, F; Verdier, P; Verzi, V; Vilanova, D; Vitale, L; Vrba, V; Wahlen, H; Washbrook, A J; Weilhammer, Peter; Weiser, C; Wicke, D; Wickens, J H; Wilkinson, G; Winter, M; Witek, M; Yushchenko, O P; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zimin, N I; Zinchenko, A I; Zupan, M

    2004-01-01

    The standard method used for tagging b-hadrons in the DELPHI experiment at the CERN LEP Collider is discussed in detail. The main ingredient of b-tagging is the impact parameters of tracks, which relies mostly on the vertex detector. Additional information, such as the mass of particles associated to a secondary vertex, significantly improves the selection efficiency and the background suppression. The paper describes various discriminating variables used for the tagging and the procedure of their combination. In addition, applications of b-tagging to some physics analyses, which depend crucially on the performance and reliability of b-tagging, are described briefly.

  2. Production and characterization of polymer nanocomposite with aligned single wall carbon nanotubes

    International Nuclear Information System (INIS)

    Chen Wei; Tao Xiaoming

    2006-01-01

    We reported a simple method to fabricate polymer nanocomposites with single-walled carbon nanotubes (SWNTs) having exceptional alignment and improved mechanical properties. The composite films were fabricated by casting a suspension of single walled carbon nanotubes in a solution of thermoplastic polyurethane and tetrahydrofuran. The orientation as well as dispersion of nanotubes was determined by scanning electron microscopy, transmission electron microscopy and polarized Raman spectroscopy. The macroscopic alignment probably results from solvent-polymer interaction induced orientation of soft segment chain during swelling and moisture curing. The tensile behavior of the aligned nanotube composite film was also studied. At a 0.5 wt.% nanotube loading, a 1.9-fold increase in Young's modulus was achieved

  3. Electrophoretic deposition of carbon nanotubes on a carbon fiber surface with different index graphitization

    International Nuclear Information System (INIS)

    Almeida, E.C.; Baldan, M.R.; Ferreira, N.G.; Edwards, E.R.

    2009-01-01

    Full text: The purpose of this work is to examine the electrophoretic deposition of carbon nanotubes powder on carbon fibers, produced at different heat treatments temperatures. Besides, a systematic study of the effects of graphitization index from substrate on the structure and morphology of CNTs has been available. Carbon fibers were produced from polyacrylonitrile at three different heat treatments temperatures, 1000, 1500 and 2000 deg C. The carbon fibers microstructure or its graphitization index may be controlled by the heat treatments temperatures. The electrophoretic deposition of carbon nanotubes was obtained with the powder of carbon nanotubes dispersed in water by ultrasonication to obtain dispersions of 0.05 mg/mL. The carbon fibers were immersed in the nanotube dispersion, and a positive potential of 10 V/cm was applied. Morphology and microstructure of carbon nanotubes on carbon fibers were obtained by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-01

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

  5. Photocatalytic decouloration of malachite green dye by application of TiO2 nanotubes

    International Nuclear Information System (INIS)

    Prado, Alexandre G.S.; Costa, Leonardo L.

    2009-01-01

    The nanotubes of titania were synthesized in a hydrothermal system and characterized by scanning electronic microscopy (SEM), FT-IR, FT-Raman, and surface charge density by surface area analyzer. These nanomaterials were applied to photocatalyse malachite green dye degradation. Photodegradation capacity of TiO 2 nanotubes was compared to TiO 2 anatase photoactivity. Malachite dye was completely degraded in 75 and 105 min of reaction photocatalysed by TiO 2 nanotubes and TiO 2 anatase, respectively. Catalysts displayed high photodegradation activity at pH 4. TiO 2 nanotubes were easily recycled whereas the reuse of TiO 2 anatase was not effective. Nanotubes maintained 80% of their activity after 10 catalytic cycles and TiO 2 anatase presented only 8% of its activity after 10 cycles.

  6. Anodic Fabrication of Ti-Ni-O Nanotube Arrays on Shape Memory Alloy

    Directory of Open Access Journals (Sweden)

    Qiang Liu

    2014-04-01

    Full Text Available Surface modification with oxide nanostructures is one of the efficient ways to improve physical or biomedical properties of shape memory alloys. This work reports a fabrication of highly ordered Ti-Ni-O nanotube arrays on Ti-Ni alloy substrates through pulse anodization in glycerol-based electrolytes. The effects of anodization parameters and the annealing process on the microstructures and surface morphology of Ti-Ni-O were studied using scanning electron microscope and Raman spectroscopy. The electrolyte type greatly affected the formation of nanotube arrays. A formation of anatase phase was found with the Ti-Ni-O nanotube arrays annealed at 450 °C. The oxide nanotubes could be crystallized to rutile phase after annealing treatment at 650 °C. The Ti-Ni-O nanotube arrays demonstrated an excellent thermal stability by keeping their nanotubular structures up to 650 °C.

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

    Directory of Open Access Journals (Sweden)

    Catherine Y. Han

    2009-01-01

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

  8. EB treatment of carbon nanotube-reinforced polymer composites

    International Nuclear Information System (INIS)

    Szebenyi, G.; Romhany, G.; Czvikovszky, T.; Vajna, B.

    2011-01-01

    Complete text of publication follows. A small amount - less than 0.5% - carbon nanotube reinforcement may improve significantly the mechanical properties of epoxy based composite materials. The basic technical problem is on one side the dispersion of the nanotubes into the viscous matrix resin. Namely the fine, powder-like - less than 100 nanometer diameter - nanotubes are prone to form aggregates. On the other side, the good connection between the nanofiber and matrix, - which is determining the success of the reinforcement, - requires some efficient adhesion promoting treatment. After an elaborate masterbatch mixing technology we applied Electron Beam treatment of epoxy-matrix polymer composites containing carbon nanotubes in presence of vinylester resins. The Raman spectra of vinylester-epoxy mixtures treated by an 8 MeV EB showed the advantage of the electron treatment. Even in the case of partially immiscible epoxy and vinylester resins, the anchorage of carbon nanotubes reflects improvement if a reasonable 25 kGy EB dose is applied. Atomic Force Microscopy as well as mechanical tests on flexural and impact properties confirm the benefits of EB treatment. Simultaneous application of multiwall carbon nanotubes and 'conventional' carbon fibers as reinforcement in vinylester modified epoxies results in new types of hybrid nanocomposites as engineering materials. The bending- and interlaminar properties of such hybrid systems showed the beneficial effect of the EB treatment. Acknowledgement: This work has been supported by the New Hungary Development Plan (Project ID: TAMOP-4.2.1/B-09/1/KMR-2010-0002).

  9. Nitrogen-doping effects on the growth, structure and electrical performance of carbon nanotubes obtained by spray pyrolysis method

    Energy Technology Data Exchange (ETDEWEB)

    Ionescu, Mihnea Ioan; Zhang Yong; Li Ruying [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON N6A 5B9 (Canada); Abou-Rachid, Hakima [Defense Research and Development Canada - Valcartier, 2459 Boulevard PieXI Nord, Quebec, QC G3J 1X5 (Canada); Sun Xueliang, E-mail: xsun@eng.uwo.ca [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON N6A 5B9 (Canada)

    2012-03-01

    Vertically aligned nitrogen-doped carbon nanotubes (CNTs) with modulated nitrogen content have been synthesized in a large scale by using spray pyrolysis chemical vapor deposition technique. The effects of nitrogen doping on the growth, structure and electrical performance of carbon nanotubes have been systematically examined. Field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman techniques have been employed to characterize the morphology, composition, and vibrational properties of nanotubes. The results indicate that the nitrogen incorporation significantly influences the growth rate, morphology, size and structure of nanotubes. Electrical measurement investigation of the nanotubes indicates that the change in electrical resistance increases with temperature and pressure as the nitrogen concentration increases inside the tubes. This work presents a versatile, safe, and easy way to scale up route of growing carbon nanotubes with controlled nitrogen content and modulated structure, and may provide an insight in developing various nitrogen-doped carbon-based nanodevices.

  10. Effects of potassium hydroxide post-treatments on the field-emission properties of thermal chemical vapor deposited carbon nanotubes.

    Science.gov (United States)

    Lee, Li-Ying; Lee, Shih-Fong; Chang, Yung-Ping; Hsiao, Wei-Shao

    2011-12-01

    In this study, a simple potassium hydroxide treatment was applied to functionalize the surface and to modify the structure of multi-walled carbon nanotubes grown on silicon substrates by thermal chemical vapor deposition. Scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and energy dispersive spectrometry were employed to investigate the mechanism causing the modified field-emission properties of carbon nanotubes. From our experimental data, the emitted currents of carbon nanotubes after potassium hydroxide treatment are enhanced by more than one order of magnitude compared with those of untreated carbon nanotubes. The emitted current density of carbon nanotubes increases from 0.44 mA/cm2 to 7.92 mA/cm2 after 30 minutes KOH treatment. This technique provides a simple, economical, and effective way to enhance the field-emission properties of carbon nanotubes.

  11. Gas tagging system development in Japan

    International Nuclear Information System (INIS)

    Sekiguchi, N.; Rindo, H.; Akiyama, T.; Miyazawa, T.; Heki, H.

    1981-05-01

    The Gas tagging method has been considered to be most desirable for a failed fuel location system for the fast breeder reactor, regarding the component reduction in the reactor vessel and rapid location during reactor operation. The gas tagging system has been designed by referring to R and D results obtained in Japan and other countries. The designed system is comprised of tag gas filling pins, cover gas sampling system, tag gas recovery and enrichment system, tag gas analyzer and system control and data handling computers. The main specifications for this system have been decided as follows; 1) Main function is location of failed fuels in core and a part of blanket region, 2) Identification capability is each subassembly, 3) Time for identification is within a few days, 4) Continuous operation with automatic start at fuel failure, 5) Detection sensitivity must cover both gas leak and pin burst. In designing the gas tagging system, the following R and D items were selected; 1) System design study, 2) Tag gas capsule development, 3) Modeling the tag gas behavior in reactor primary cooling system, 4) Tag gas recovery and enrichment system, 5) Computer code development for tag gas isotope ratio change estimation. Details of the Japanese gas tagging system development appear in this paper. (author)

  12. Freestanding bucky paper with high strength from multi-wall carbon nanotubes

    International Nuclear Information System (INIS)

    Li, Zhonglai; Xu, Ju; O'Byrne, Justin P.; Chen, Lan; Wang, Kaixue; Morris, Michael A.; Holmes, Justin D.

    2012-01-01

    Bucky papers have been investigated by some research groups, however, due to different qualities of carbon nanotubes used, various results of strength and electronic properties were reported in the literatures. In this article, the effects of carbon nanotubes synthesized over different catalysts on the qualities of bucky papers were systemically investigated. Multi-wall carbon nanotubes were synthesized over a series of MgO supported catalysts with different weight ratios of Mo and Co. As the ratios of Mo/Co in the catalysts were increased from 0 to 3, the yields of carbon nanotubes were enhanced from 7 wt% to 400 wt%. However, the yield enhancement of carbon nanotubes was achieved at the expense of higher proportion of structural defects within carbon nanotubes, which has been proved by Raman spectroscopy and thermogravimetry analysis. It was demonstrated that the tensile strength of bucky paper composed of numerous MCNTs bundles strongly depends on the structure of carbon nanotubes used. By optimizing reaction conditions, a bucky paper with high strain up to 15.36 MPa and electrical conductivity of 61.17 S cm −1 was obtained by Supercritical Fluid (SCF) drying technique. -- Highlights: ► Multi-wall carbon nanotube bucky paper. ► Structural defects of carbon nanotubes. ► CoMo catalyst. ► Tensile strength of bucky paper.

  13. Patterned growth of carbon nanotubes obtained by high density plasma chemical vapor deposition

    Science.gov (United States)

    Mousinho, A. P.; Mansano, R. D.

    2015-03-01

    Patterned growth of carbon nanotubes by chemical vapor deposition represents an assembly approach to place and orient nanotubes at a stage as early as when they are synthesized. In this work, the carbon nanotubes were obtained at room temperature by High Density Plasmas Chemical Vapor Deposition (HDPCVD) system. This CVD system uses a new concept of plasma generation, where a planar coil coupled to an RF system for plasma generation was used with an electrostatic shield for plasma densification. In this mode, high density plasmas are obtained. We also report the patterned growth of carbon nanotubes on full 4-in Si wafers, using pure methane plasmas and iron as precursor material (seed). Photolithography processes were used to pattern the regions on the silicon wafers. The carbon nanotubes were characterized by micro-Raman spectroscopy, the spectra showed very single-walled carbon nanotubes axial vibration modes around 1590 cm-1 and radial breathing modes (RBM) around 120-400 cm-1, confirming that high quality of the carbon nanotubes obtained in this work. The carbon nanotubes were analyzed by atomic force microscopy and scanning electron microscopy too. The results showed that is possible obtain high-aligned carbon nanotubes with patterned growth on a silicon wafer with high reproducibility and control.

  14. Secure passive RFID tag with seal

    Science.gov (United States)

    Nekoogar, Faranak; Reynolds, Matthew; Lefton, Scott; Dowla, Farid; Twogood, Richard

    2017-11-14

    A secure passive RFID tag system comprises at least one base station and at least one passive RFID tag. The tag includes a fiber optic cable with the cable ends sealed within the tag and the middle portion forming an external loop. The loop may be secured to at least portions of an object. The tag transmits and receives an optical signal through the fiber optic cable, and the cable is configured to be damaged or broken in response to removal or tampering attempts, wherein the optical signal is significantly altered if the cable is damaged or broken. The tag transmits the optical signal in response to receiving a radio signal from the base station and compares the transmitted optical signal to the received optical signal. If the transmitted optical signal and the received optical signal are identical, the tag transmits an affirmative radio signal to the base station.

  15. Confocal Raman microscopy

    CERN Document Server

    Dieing, Thomas; Hollricher, Olaf

    2018-01-01

    This second edition provides a cutting-edge overview of physical, technical and scientific aspects related to the widely used analytical method of confocal Raman microscopy. The book includes expanded background information and adds insights into how confocal Raman microscopy, especially 3D Raman imaging, can be integrated with other methods to produce a variety of correlative microscopy combinations. The benefits are then demonstrated and supported by numerous examples from the fields of materials science, 2D materials, the life sciences, pharmaceutical research and development, as well as the geosciences.

  16. Thermal Analysis of Copper-Titanium-Multiwall Carbon Nanotube Composites.

    Science.gov (United States)

    Hamamda, Smail; Jari, Ahmed; Revo, S; Ivanenko, K; Jari, Youcef; Avramenko, T

    2017-12-01

    The aim of this research is the thermostructural study of Cu-Ti, Cu-Ti 1 vol% multiwall carbon nanotubes (MWCNTs) and Cu-Ti 3 vol% MWCNTs. Several investigation techniques were used to achieve this objective. Dilatometric data show that the coefficient of thermal expansion of the nanocomposite containing less multiwall carbon nanotubes is linear and small. The same nanocomposite exhibits regular heat transfer and weak mass exchange with the environment. Raman spectroscopy shows that the nanocomposite with more MWCNTs contains more defects. This implies that the carbon nanotubes have better dispersion in Cu-Ti 1 vol% MWCNTs. Infrared spectroscopy reveals that Cu-Ti 1 vol% MWCNTs has better crystallinity than Cu-Ti 3 vol% MWCNTs.

  17. Holographic Raman lidar

    International Nuclear Information System (INIS)

    Andersen, G.

    2000-01-01

    Full text: We have constructed a Raman lidar system that incorporates a holographic optical element. By resolving just 3 nitrogen lines in the Resonance Raman spectroscopy (RRS) spectrum, temperature fits as good as 1% at altitudes of 20km can be made in 30 minutes. Due to the narrowband selectivity of the HOE, the lidar provides measurements over a continuous 24hr period. By adding a 4th channel to capture the Rayleigh backscattered light, temperature profiles can be extended to 80km

  18. One-step synthesis of Zn doped titania nanotubes and investigation of their visible photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Benjwal, Poonam [Advanced Nanoengineering Materials Laboratory, Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Kar, Kamal K., E-mail: kamalkk@iitk.ac.in [Advanced Nanoengineering Materials Laboratory, Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Advanced Nanoengineering Materials Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

    2015-06-15

    Highly oriented undoped and Zn-doped titania (TiO{sub 2}) nanotubes were electrochemically fabricated by one-step anodization of titanium foil in a freshly prepared aqueous solution of zinc fluoride (ZnF{sub 2}) and ethylene glycol (EG). XRD and Raman spectroscopy unveiled the typical characteristic of anatase phase of TiO{sub 2} nanotube without any distinct dopant related peaks. SEM and AFM observation confirmed the formation of nanotubes and revealed that the Zn doping did not distort the tube morphology of TiO{sub 2}. The doping of Zn was confirmed by energy dispersive X-ray as well as X-ray photospectroscopy. Due to one-step anodization process, instead of surface doping, the Zn{sup 2+} ions were incorporated into the bulk of TiO{sub 2} nanotubes. With increasing Zn doping in nanotubes, a gradual decrease in the band gap of TiO{sub 2} (2.84 eV) was observed. Photoluminescence measurements revealed that the doping of Zn enhanced the number of charge carriers, which eventually boosted the photocatalytic activity of TiO{sub 2} nanotubes. Compared to undoped nanotubes, the as prepared Zn-doped TiO{sub 2}-nanotubes showed excellent photocatalytic activity for methylene blue degradation (reaction rate constant k = 0.19 min{sup −1}) under visible light irradiation. - Highlights: • A facile one-step anodization method is used for Zn doped TiO{sub 2}-nanotubes synthesis. • Zn{sup 2+} ions are doped into the bulk of TiO{sub 2} nanotubes. • Doped TiO{sub 2}-nanotubes unveil pure anatase phase and reduced band gap. • Compared to undoped, doped TiO{sub 2} nanotubes exhibit enhanced photocatalytic activity.

  19. Preparation and characterization of titanate nanotubes/carbon composites

    International Nuclear Information System (INIS)

    Wang Xiaodong; Pan Hui; Xue Xiaoxiao; Qian Junjie; Yu Laigui; Yang Jianjun; Zhang Zhijun

    2011-01-01

    Highlights: → Titanate nanotubes/carbon composites were synthesized from TiO 2 -carbon composites. → The carbon shell of TiO 2 particles obstructed the reaction between TiO 2 and NaOH. → TEM, XRD, and Raman spectra reveal the formation processes of the TNT/CCs. - Abstract: Titanate nanotubes/carbon composites(TNT/CCs) were synthesized by allowing carbon-coated TiO 2 (CCT) powder to react with a dense aqueous solution of NaOH at 120 deg. C for a proper period of time. As-prepared CCT and TNT/CCs were characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectrometry. The processes for formation of titanate nanotubes/carbon composites were discussed. It was found that the TiO 2 particles in TiO 2 -carbon composite were enwrapped by a fine layer of carbon with a thickness of about 4 nm. This carbon layer functioned to inhibit the transformation from anatase TiO 2 to orthorhombic titanate. As a result, the anatase TiO 2 in CCT was incompletely transformed into orthorhombic titanate nanotubes upon 24 h of reaction in the dense and hot NaOH solution. When the carbon layers were gradually peeled off along with the formation of more orthorhombic titanate nanotubes at extended reaction durations (e.g., 72 h), anatase TiO 2 particles in CCT were completely transformed into orthorhombic titanate nanotubes, yielding TNT/CCs whose morphology was highly dependent on the reaction time and temperature.

  20. Effect of hydrogen on the growth and morphology of single wall carbon nanotubes synthesized on a Fe-Mo/MgO catalytic system

    Energy Technology Data Exchange (ETDEWEB)

    Biris, Alexandru R. [National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj Napoca, RO-3400 (Romania)], E-mail: biris@oc1.itim-cj.ro; Li Zhongrui; Dervishi, Enkeleda [Applied Science Department, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States); Nanotechnology Center, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States); Lupu, Dan [National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj Napoca, RO-3400 (Romania); Xu Yang; Saini, Viney [Applied Science Department, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States); Nanotechnology Center, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States); Watanabe, Fumiya [Nanotechnology Center, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States); Biris, Alexandru S. [Applied Science Department, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States); Nanotechnology Center, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States)], E-mail: asbiris@ualr.edu

    2008-04-21

    Single wall carbon nanotubes were synthesized from thermal pyrolysis of methane on a Fe-Mo/MgO catalyst by radio frequency catalytic chemical vapor deposition (RF-CVD) using argon as a carrier gas. Controlled amounts of hydrogen (H{sub 2}/CH{sub 4}=0-1 v/v) were introduced in separate experiments along with the carbon source. The properties and morphology of the synthesized single wall carbon nanotubes were monitored by transmission electron microscopy, Raman scattering, and thermogravimetric analysis. The nanotubes with the highest crystallinity were obtained with H{sub 2}/CH{sub 4}=0.6. By monitoring the Radial Breathing Modes present in the Raman spectra of the single-wall carbon nanotube samples, the variation of the structural and morphological properties of the carbon nanotubes with the flow level of hydrogen, reflect changes of the catalyst systems induced by the presence of hydrogen.

  1. Effect of Growth Temperature on Bamboo-shaped Carbon–Nitrogen (C–N Nanotubes Synthesized Using Ferrocene Acetonitrile Precursor

    Directory of Open Access Journals (Sweden)

    Dobal PramodSingh

    2008-01-01

    Full Text Available Abstract This investigation deals with the effect of growth temperature on the microstructure, nitrogen content, and crystallinity of C–N nanotubes. The X-ray photoelectron spectroscopic (XPS study reveals that the atomic percentage of nitrogen content in nanotubes decreases with an increase in growth temperature. Transmission electron microscopic investigations indicate that the bamboo compartment distance increases with an increase in growth temperature. The diameter of the nanotubes also increases with increasing growth temperature. Raman modes sharpen while the normalized intensity of the defect mode decreases almost linearly with increasing growth temperature. These changes are attributed to the reduction of defect concentration due to an increase in crystal planar domain sizes in graphite sheets with increasing temperature. Both XPS and Raman spectral observations indicate that the C–N nanotubes grown at lower temperatures possess higher degree of disorder and higher N incorporation.

  2. Electrochemical Tuning of Electronic Structure of Carbon Nanotubes and Fullerene Peapods

    Czech Academy of Sciences Publication Activity Database

    Kavan, Ladislav; Dunsch, L.; Kataura, H.

    2004-01-01

    Roč. 42, - (2004), s. 1011-1019 ISSN 0008-6223 R&D Projects: GA AV ČR IAA4040306; GA MŠk ME 487 Institutional research plan: CEZ:AV0Z4040901 Keywords : electrochemical analysis * carbon nanotubes * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 3.331, year: 2004

  3. Electrochemical Tuning of High Energy Photon Branches of Double Wall Carbon Nanotubes

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Kavan, Ladislav; Zukalová, Markéta; Dunsch, L.

    2004-01-01

    Roč. 42, č. 14 (2004), s. 2915-2920 ISSN 0008-6223 R&D Projects: GA AV ČR IAA4040306 Institutional research plan: CEZ:AV0Z4040901 Keywords : carbon nanotubes * Raman spectroscopy * electrochemical properties Subject RIV: CG - Electrochemistry Impact factor: 3.331, year: 2004

  4. Enhancement in ballistic performance of composite hard armor through carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Jason Gibson

    2013-12-01

    Full Text Available The use of carbon nanotubes in composite hard armor is discussed in this study. The processing techniques to make various armor composite panels consisting of Kevlar®29 woven fabric in an epoxy matrix and the subsequent V50 test results for both 44 caliber soft-point rounds and 30 caliber FSP (fragment simulated projectile threats are presented. A 6.5% improvement in the V50 test results was found for a combination of 1.65 wt% loading of carbon nanotubes and 1.65 wt% loading of milled fibers. The failure mechanism of carbon nanotubes during the ballistic event is discussed through scanning electron microscope images of the panels after the failure. Raman Spectroscopy was also utilized to evaluate the residual strain in the Kevlar®29 fibers post shoot. The Raman Spectroscopy shows a Raman shift of 25 cm−1 for the Kevlar®29 fiber utilized in the composite panel that had an enhancement in the V50 performance by using milled fiber and multi-walled carbon nanotubes. Evaluating both scenarios where an improvement was made and other panels without any improvement allows for understanding of how loading levels and synergistic effects between carbon nanotubes and milled fibers can further enhance ballistic performance.

  5. Scalable Faceted Ranking in Tagging Systems

    Science.gov (United States)

    Orlicki, José I.; Alvarez-Hamelin, J. Ignacio; Fierens, Pablo I.

    Nowadays, web collaborative tagging systems which allow users to upload, comment on and recommend contents, are growing. Such systems can be represented as graphs where nodes correspond to users and tagged-links to recommendations. In this paper we analyze the problem of computing a ranking of users with respect to a facet described as a set of tags. A straightforward solution is to compute a PageRank-like algorithm on a facet-related graph, but it is not feasible for online computation. We propose an alternative: (i) a ranking for each tag is computed offline on the basis of tag-related subgraphs; (ii) a faceted order is generated online by merging rankings corresponding to all the tags in the facet. Based on the graph analysis of YouTube and Flickr, we show that step (i) is scalable. We also present efficient algorithms for step (ii), which are evaluated by comparing their results with two gold standards.

  6. Building Tag Clouds in Perl and PHP

    CERN Document Server

    Bumgardner, Jim

    2006-01-01

    Tag clouds are everywhere on the web these days. First popularized by the web sites Flickr, Technorati, and del.icio.us, these amorphous clumps of words now appear on a slew of web sites as visual evidence of their membership in the elite corps of "Web 2.0." This PDF analyzes what is and isn't a tag cloud, offers design tips for using them effectively, and then goes on to show how to collect tags and display them in the tag cloud format. Scripts are provided in Perl and PHP. Yes, some have said tag clouds are a fad. But as you will see, tag clouds, when used properly, have real merits. More

  7. Spontaneous Ag-Nanoparticle Growth at Single-Walled Carbon Nanotube Defect Sites: A Tool for In Situ Generation of SERS Substrate

    Directory of Open Access Journals (Sweden)

    Jason Maley

    2011-01-01

    Full Text Available Silver nanoparticles were spontaneously formed on pristine and oxidized single-wall nanotubes. Nanoparticles were observed on carbon nanotubes with AFM, and the presence of Ag nanoparticles were confirmed by ESR experiments. Raman spectroscopy of the Ag-treated carbon nanotubes had a 4–10X enhancement of intensity compared to untreated carbon nanotubes. Ag nanoparticles formed at defect sites on the CNT surface, where free electrons located at the defect sites reduced Ag+ to Ag. A mechanism for the propagation of the nanoparticles is through a continual negative charge generation on the nanoparticle by electron transfer from doublet oxygen (O2−.

  8. Preparation of Hydroxypropyl-β-cyclodextrin Cross-linked Multi-walled Carbon Nanotubes and Their Application in Enantioseparation of Clenbuterol

    Institute of Scientific and Technical Information of China (English)

    Yu Jingang; Huang Dushu; Huang Kelong; Hong Yong

    2011-01-01

    A method of cross-linking multi-walled carbon nanotubes by a nucleophilic substitution of brominated multi-walled carbon nanotubes using hydroxypropyl-β-cyclodextrin anions was studied. The modified multi-walled carbon nanotube samples were characterized using thermogravimetric analysis, energy-dispersive X-ray spectros-copy, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and Fourier transform infrared spectroscopy. The hydroxypropyi-β-cyclodextrin modified multi-walled carbon nanotubes were used as a chiral stationary phase additive for thin-layer chromatography to separate clenbuterol enantiomers, and the chiral separation factor was increased.

  9. Understanding why users tag: A survey of tagging motivation literature and results from an empirical study.

    Science.gov (United States)

    Strohmaier, Markus; Körner, Christian; Kern, Roman

    2012-12-01

    While recent progress has been achieved in understanding the structure and dynamics of social tagging systems, we know little about the underlying user motivations for tagging, and how they influence resulting folksonomies and tags. This paper addresses three issues related to this question. (1) What distinctions of user motivations are identified by previous research, and in what ways are the motivations of users amenable to quantitative analysis? (2) To what extent does tagging motivation vary across different social tagging systems? (3) How does variability in user motivation influence resulting tags and folksonomies? In this paper, we present measures to detect whether a tagger is primarily motivated by categorizing or describing resources, and apply these measures to datasets from seven different tagging systems. Our results show that (a) users' motivation for tagging varies not only across, but also within tagging systems, and that (b) tag agreement among users who are motivated by categorizing resources is significantly lower than among users who are motivated by describing resources . Our findings are relevant for (1) the development of tag-based user interfaces, (2) the analysis of tag semantics and (3) the design of search algorithms for social tagging systems.

  10. Learner Corpora without Error Tagging

    Directory of Open Access Journals (Sweden)

    Rastelli, Stefano

    2009-01-01

    Full Text Available The article explores the possibility of adopting a form-to-function perspective when annotating learner corpora in order to get deeper insights about systematic features of interlanguage. A split between forms and functions (or categories is desirable in order to avoid the "comparative fallacy" and because – especially in basic varieties – forms may precede functions (e.g., what resembles to a "noun" might have a different function or a function may show up in unexpected forms. In the computer-aided error analysis tradition, all items produced by learners are traced to a grid of error tags which is based on the categories of the target language. Differently, we believe it is possible to record and make retrievable both words and sequence of characters independently from their functional-grammatical label in the target language. For this purpose at the University of Pavia we adapted a probabilistic POS tagger designed for L1 on L2 data. Despite the criticism that this operation can raise, we found that it is better to work with "virtual categories" rather than with errors. The article outlines the theoretical background of the project and shows some examples in which some potential of SLA-oriented (non error-based tagging will be possibly made clearer.

  11. B-tagging in CMS at LHC

    CERN Document Server

    Cucciarelli, S

    2003-01-01

    This report provides a review of the main algorithms for offline inclusive b-tagging developed within the CMS community. Two b-tag algorithms, one based on the impact parameter measurement and the other based on the secondary vertices are discussed. The performance of these algorithms are presented for several jet transverse energies and pseudorapidity regions. An additional decay length based b-tag is also described and its preliminary performance is presented. (4 refs) .

  12. Purification of carbon nanotubes via selective heating

    Science.gov (United States)

    Rogers, John A.; Wilson, William L.; Jin, Sung Hun; Dunham, Simon N.; Xie, Xu; Islam, Ahmad; Du, Frank; Huang, Yonggang; Song, Jizhou

    2017-11-21

    The present invention provides methods for purifying a layer of carbon nanotubes comprising providing a precursor layer of substantially aligned carbon nanotubes supported by a substrate, wherein the precursor layer comprises a mixture of first carbon nanotubes and second carbon nanotubes; selectively heating the first carbon nanotubes; and separating the first carbon nanotubes from the second carbon nanotubes, thereby generating a purified layer of carbon nanotubes. Devices benefiting from enhanced electrical properties enabled by the purified layer of carbon nanotubes are also described.

  13. Sensor-based material tagging system

    International Nuclear Information System (INIS)

    Vercellotti, L.C.; Cox, R.W.; Ravas, R.J.; Schlotterer, J.C.

    1991-01-01

    Electronic identification tags are being developed for tracking material and personnel. In applying electronic identification tags to radioactive materials safeguards, it is important to measure attributes of the material to ensure that the tag remains with the material. The addition of a microcontroller with an on-board analog-to-digital converter to an electronic identification tag application-specific integrated-circuit has been demonstrated as means to provide the tag with sensor data. Each tag is assembled into a housing, which serves as a scale for measuring the weight of a paint-can-sized container and its contents. Temperature rise of the can above ambient is also measured, and a piezoelectric detector detects disturbances and immediately puts the tag into its alarm and beacon mode. Radiation measurement was also considered, but the background from nearby containers was found to be excessive. The sensor-based tagging system allows tracking of the material in cans as it is stored in vaults or is moved through the manufacturing process. The paper presents details of the sensor-based material tagging system and describes a demonstration system

  14. Graph based techniques for tag cloud generation

    DEFF Research Database (Denmark)

    Leginus, Martin; Dolog, Peter; Lage, Ricardo Gomes

    2013-01-01

    Tag cloud is one of the navigation aids for exploring documents. Tag cloud also link documents through the user defined terms. We explore various graph based techniques to improve the tag cloud generation. Moreover, we introduce relevance measures based on underlying data such as ratings...... or citation counts for improved measurement of relevance of tag clouds. We show, that on the given data sets, our approach outperforms the state of the art baseline methods with respect to such relevance by 41 % on Movielens dataset and by 11 % on Bibsonomy data set....

  15. Flavour Tagging developments within the LHCb experiment

    CERN Document Server

    Grabalosa, Marc

    Flavour Tagging at the LHCb experiment is a fundamental tool for the measurement of B oscillations and the study of CP violation. This document explains the development of different tagging techniques and the different strategies used to combine them to determine the flavour of the B meson as precisely as possible. The response of the tagging algorithms also needs to be optimized and calibrated. Both procedures are described using the available LHCb datasets corresponding to various integrated luminosities. First results on the tagging performances are shown for different control channels and physics measurements.

  16. Using Interference to Block RFID Tags

    DEFF Research Database (Denmark)

    Krigslund, Rasmus; Popovski, Petar; Pedersen, Gert Frølund

    We propose a novel method to block RFID tags from responding, using intentional interference. We focus on the experimental evaluation, where we impose interference on the download and uplink, respectively. The results are positive, where modulated CCI shows most effective to block a tag.......We propose a novel method to block RFID tags from responding, using intentional interference. We focus on the experimental evaluation, where we impose interference on the download and uplink, respectively. The results are positive, where modulated CCI shows most effective to block a tag....

  17. Discharge residence of TLD tagged fish

    International Nuclear Information System (INIS)

    Romberg, G.P.; Prepejchal, W.

    1974-01-01

    Although visual observations suggested that fish remained in the discharge for considerable periods, temperature-sensitive tags indicated the majority of fish spend less than 50 hr or 10 percent of the time at discharge temperatures. During 1974 a second fish tagging study was conducted, using temperature-sensitive tags to yield discharge residence times of Lake Michigan salmonids at Point Beach thermal discharge. Preliminary results revealed that many fish tag values were close to Unit I line indicating that calculated maximum discharge residence times for these fish will be nearly 100 percent of the elapsed time

  18. SEM and Raman studies of CNT films on porous Si

    Science.gov (United States)

    Belka, R.; Keczkowska, J.; Suchańska, M.; Firek, P.; Wronka, H.; Kozłowski, M.; Radomska, J.; Czerwosz, E.; Craciunoiu, F.

    2017-08-01

    Carbon nanotube (CNT) films deposited on different porous silica substrates were studied by Scanning Electron Microscopy (SEM) and Raman Spectroscopy (RS). The films samples were prepared by a two-step method consisting of PVD and CVD processes. In the first step the nanocomposite Ni-C film was obtained by evaporation in dynamic vacuum from two separated sources of fullerenes and nickel acetate. Those films were deposited on porous silica and DLC/porous silica substrates. Analysis of SEM imaging showed that the obtained film are composed of carbon nanotubes, the distribution, size and quality of which depend on the type of substrate. The CNT films were studied by RS method to determine the influence of the substrate type on disordering of carbonaceous structure and quality of CNT in deposited films.

  19. Electrochemical Capacitors Based on Aligned Carbon Nanotubes Directly Synthesized on Tantalum Substrates

    International Nuclear Information System (INIS)

    Kim, Byung Woo; Chung, Hae Geun; Kim, Woong; Min, Byoung Koun; Kim, Hong Gon

    2010-01-01

    We demonstrate that vertically aligned carbon nanotubes can be synthesized directly on tantalum substrate via waterassisted chemical vapor deposition and evaluate their properties as electrochemical capacitors. The mean diameter of the carbon nanotubes was 7.1 ± 1.5 nm, and 70% of them had double walls. The intensity ratio of G-band to D-band in Raman spectra was as high as 5, indicating good quality of the carbon nanotubes. Owing to the alignment and low equivalent series resistance, the carbon nanotube based supercapacitors showed good rate performance. Rectangular shape of cyclic voltammogram was maintained even at the scan rate of > 1 V/s in 1 M sulfuric acid aqueous solution. Specific capacitance was well-retained (∼94%) even when the discharging current density dramatically increased up to 145 A/g. Consequently, specific power as high as 60 kW/kg was obtained from as-grown carbon nanotubes in aqueous solution. Maximum specific energy of ∼20 Wh/kg was obtained when carbon nanotubes were electrochemically oxidized and operated in organic solution. Demonstration of direct synthesis of carbon nanotubes on tantalum current collectors and their applications as supercapacitors could be an invaluable basis for fabrication of high performance carbon nanotube supercapacitors

  20. The effect of different order of purification treatments on the purity of multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Xinlong [College of Materials Science and Engineering, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, 2999 North People Road, Shanghai 201620 (China); Department of Biological and Chemical Engineering, Guangxi University of Technology, 268 Donghuan Road, Liuzhou 545006 (China); Wei, Yizhe [College of Materials Science and Engineering, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, 2999 North People Road, Shanghai 201620 (China); Zou, Liming, E-mail: lmzou@dhu.edu.cn [College of Materials Science and Engineering, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, 2999 North People Road, Shanghai 201620 (China); Xu, Su [College of Materials Science and Engineering, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, 2999 North People Road, Shanghai 201620 (China)

    2013-07-01

    The multiwalled carbon nanotubes were purified with different order treatments of gas phase and liquid phase. Amorphous carbon and iron catalysts were removed and some oxygen-containing groups were attached to the surface of multiwalled carbon nanotubes after purification. The multiwalled carbon nanotubes were determined and characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, Boehm's neutralizing titration method and weighing method. The morphology of multiwalled carbon nanotubes was verified using scanning electron microscopy and transmission electron microscopy. The results indicated amorphous carbon and iron catalysts were removed completely while the structure of multiwalled carbon nanotubes was slightly destructed by two treatment methods. Three principal oxygen-containing groups on the surface of multiwalled carbon nanotubes were carboxyl, lactone and phenolic hydroxyl in descending order of their concentrations. The method I including gas phase treatment firstly and then liquid phase treatment, is more effective to purify multiwalled carbon nanotubes and to protect the structure of multiwalled carbon nanotubes than method II including liquid phase treatment firstly and then gas phase treatment.

  1. Study of the growth of CeO2 nanoparticles onto titanate nanotubes

    Science.gov (United States)

    Marques, Thalles M. F.; Ferreira, Odair P.; da Costa, Jose A. P.; Fujisawa, Kazunori; Terrones, Mauricio; Viana, Bartolomeu C.

    2015-12-01

    We report the study of the growth of CeO2 nanoparticles on the external walls and Ce4+ intercalation within the titanate nanotubes. The materials were fully characterized by multiple techniques, such as: Raman spectroscopy, infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The ion exchange processes in the titanate nanotubes were carried out using different concentrations of Ce4+ in aqueous solution. Our results indicate that the growth of CeO2 nanoparticles grown mediated by the hydrolysis in the colloidal species of Ce and the attachment onto the titanate nanotubes happened and get it strongly anchored to the titanate nanotube surface by a simple electrostatic interaction between the nanoparticles and titanate nanotubes, which can explain the small size and even distribution of nanoparticles on titanate supports. It was demonstrated that it is possible to control the amount and size of CeO2 nanoparticles onto the nanotube surface, the species of the Ce ions intercalated between the layers of titanate nanotubes, and the materials could be tuned for using in specific catalysis in according with the amount of CeO2 nanoparticles, their oxygen vacancies/defects and the types of Ce species (Ce4+ or Ce3+) present into the nanotubes.

  2. Gold Nanoparticles as Probes for Nano-Raman Spectroscopy: Preliminary Experimental Results and Modeling

    Directory of Open Access Journals (Sweden)

    V. Le Nader

    2012-01-01

    Full Text Available This paper presents an effective Tip-Enhanced Raman Spectrometer (TERS in backscattering reflection configuration. It combines a tip-probe nanopositioning system with Raman spectroscope. Specific tips were processed by anchoring gold nanoparticles on the apex of tapered optical fibers, prepared by an improved chemical etching method. Hence, it is possible to expose a very small area of the sample (~20 nm2 to the very strong local electromagnetic field generated by the lightning rod effect. This experimental configuration was modelled and optimised using the finite element method, which takes into account electromagnetic effects as well as the plasmon resonance. Finally, TERS measurements on single-wall carbon nanotubes were successfully performed. These results confirm the high Raman scattering enhancement predicted by the modelling, induced by our new nano-Raman device.

  3. Preferential adsorption of NH3 gas molecules on MWCNT defect sites probed using in situ Raman spectroscopy

    CSIR Research Space (South Africa)

    Chimowa, George

    2017-06-01

    Full Text Available The preferential adsorption of NH(sub3) gas molecules on multi-walled carbon nanotubes (MWCNTs) was studied using in situ Raman spectroscopy. It was observed that the full widths at half maximum of the G band and the intensity ratio I(sub2D...

  4. Origin of mechanical modifications in poly (ether ether ketone)/carbon nanotube composite

    International Nuclear Information System (INIS)

    Pavlenko, Ekaterina; Puech, Pascal; Bacsa, Wolfgang; Boyer, François; Olivier, Philippe; Sapelkin, Andrei; King, Stephen; Heenan, Richard; Pons, François; Gauthier, Bénédicte; Cadaux, Pierre-Henri

    2014-01-01

    Variations in the hardness of a poly (ether ether ketone) beam electrically modified with multi-walled carbon nanotubes (MWCNT, 0.5%-3%) are investigated. It is shown that both rupture and hardness variations correlate with the changes in carbon nanotube concentration when using micro indentation and extended Raman imaging. Statistical analysis of the relative spectral intensities in the Raman image is used to estimate local tube concentration and polymer crystallinity. We show that the histogram of the Raman D band across the image provides information about the amount of MWCNTs and the dispersion of MWCNTs in the composite. We speculate that we have observed a local modification of the ordering between pure and modified polymer. This is partially supported by small angle neutron scattering measurements, which indicate that the agglomeration state of the MWCNTs is the same at the concentrations studied.

  5. Origin of mechanical modifications in poly (ether ether ketone)/carbon nanotube composite

    Energy Technology Data Exchange (ETDEWEB)

    Pavlenko, Ekaterina; Puech, Pascal; Bacsa, Wolfgang, E-mail: wolfgang.bacsa@cemes.fr [CEMES-CNRS and University of Toulouse, 29 Jeanne Marvig, 31055 Toulouse (France); Boyer, François; Olivier, Philippe [Université de Toulouse, Institut Clément Ader, I.U.T. Université Paul Sabatier - 133C Avenue de Rangueil - B.P. 67701, 31077 Toulouse CEDEX 4 (France); Sapelkin, Andrei [School of Physics and Astronomy, Queen Mary, University of London, Mile End Road, E1 4NS London (United Kingdom); King, Stephen; Heenan, Richard [ISIS Facility, Rutherford Appleton Laboratory, Chilton, OX11 0QX Didcot (United Kingdom); Pons, François; Gauthier, Bénédicte; Cadaux, Pierre-Henri [AIRBUS FRANCE (B.E. M and P Toulouse), 316 Route de Bayonne, 31060 Toulouse (France)

    2014-06-21

    Variations in the hardness of a poly (ether ether ketone) beam electrically modified with multi-walled carbon nanotubes (MWCNT, 0.5%-3%) are investigated. It is shown that both rupture and hardness variations correlate with the changes in carbon nanotube concentration when using micro indentation and extended Raman imaging. Statistical analysis of the relative spectral intensities in the Raman image is used to estimate local tube concentration and polymer crystallinity. We show that the histogram of the Raman D band across the image provides information about the amount of MWCNTs and the dispersion of MWCNTs in the composite. We speculate that we have observed a local modification of the ordering between pure and modified polymer. This is partially supported by small angle neutron scattering measurements, which indicate that the agglomeration state of the MWCNTs is the same at the concentrations studied.

  6. Raman spectrum of asphaltene

    KAUST Repository

    Abdallah, Wael A.; Yang, Yang

    2012-01-01

    Asphaltenes extracted from seven different crude oils representing different geological formations from around the globe were analyzed using the Raman spectroscopic technique. Each spectrum is fitted with four main peaks using the Gaussian function. On the basis of D1 and G bands of the Raman spectrum, asphaltene indicated an ordered structure with the presence of boundary defected edges. The average aromatic sheet size of the asphaltene molecules is estimated within the range of 1.52-1.88 nm, which represents approximately seven to eight aromatic fused rings. This estimation is based on the integrated intensity of D1 and G bands, as proposed by Tunistra and Koenig. The results here are in perfect agreement with so many other used techniques and indicate the potential applicability of Raman measurements to determine the average aromatic ring size and its boundary. © 2012 American Chemical Society.

  7. Raman spectrum of asphaltene

    KAUST Repository

    Abdallah, Wael A.

    2012-11-05

    Asphaltenes extracted from seven different crude oils representing different geological formations from around the globe were analyzed using the Raman spectroscopic technique. Each spectrum is fitted with four main peaks using the Gaussian function. On the basis of D1 and G bands of the Raman spectrum, asphaltene indicated an ordered structure with the presence of boundary defected edges. The average aromatic sheet size of the asphaltene molecules is estimated within the range of 1.52-1.88 nm, which represents approximately seven to eight aromatic fused rings. This estimation is based on the integrated intensity of D1 and G bands, as proposed by Tunistra and Koenig. The results here are in perfect agreement with so many other used techniques and indicate the potential applicability of Raman measurements to determine the average aromatic ring size and its boundary. © 2012 American Chemical Society.

  8. Recent development of carbon nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Yamabe, Tokio [Div. of Molecular Engineering, Kyoto Univ. (Japan); [Inst. for Fundamental Chemistry, Kyoto (Japan)

    1995-03-15

    Recent developments of carbon nanotubes are reviewed. Analytical solutions for the electronic structure of carbon nanotube on the basis of thight-binding approximation are presented and interpreted using the concepts of crystal orbital. The electronic properties of actual carbon nanotubes are presented. The electronic structures of carbon nanotubes in the presence of magnetic fiels are also summerized. (orig.)

  9. Preparation and desalination performance of multiwall carbon nanotubes

    International Nuclear Information System (INIS)

    Zhang Dengsong; Shi Liyi; Fang Jianhui; Dai Kai; Li Xuanke

    2006-01-01

    Multiwall carbon nanotubes (MWCNTs) were prepared by catalytic decomposition of methane at 680-700 deg. C, using nickel oxide-silica binary aerogels as the catalyst. The morphological structure of MWCNTs was investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The results revealed that MWCNTs had a diameter of 40-60 nm, with high quality and high length/diameter ratio, and some metal catalyst particles were encapsulated at the tip of nanotubes. Using MWCNTs as the electrodes of flow-through capacitor (FTC), desalination performance was investigated. The results showed that modification methods had great effect on desalination performance of MWCNTs. The removal amount of NaCl was generally dependent on the surface area and pore volume of MWCNTs. After modification in diluted HNO 3 solution with ultrasonic and then ball milling, the metal catalyst particles at the tip of nanotubes disappeared, the nanotube length became short, the cap at the tip of nanotubes was opened, the internal surface area could be effectively used, leading to increasing the specific surface area and pore volume for MWCNTs, and thus, the desalination performance thereof was the best of all

  10. Engineering the ATLAS TAG Browser

    International Nuclear Information System (INIS)

    Zhang Qizhi

    2011-01-01

    ELSSI is a web-based event metadata (TAG) browser and event-level selection service for ATLAS. In this paper, we describe some of the challenges encountered in the process of developing ELSSI, and the software engineering strategies adopted to address those challenges. Approaches to management of access to data, browsing, data rendering, query building, query validation, execution, connection management, and communication with auxiliary services are discussed. We also describe strategies for dealing with data that may vary over time, such as run-dependent trigger decision decoding. Along with examples, we illustrate how programming techniques in multiple languages (PHP, JAVASCRIPT, XML, AJAX, and PL/SQL) have been blended to achieve the required results. Finally, we evaluate features of the ELSSI service in terms of functionality, scalability, and performance.

  11. To tag or not to tag: animal welfare, conservation and stakeholder considerations in fish tracking studies that use electronic tags

    Energy Technology Data Exchange (ETDEWEB)

    Cooke, Steven J.; Nguyen, Vivian M.; Murchie, Karen J.; Thiem, Jason D.; Donaldson, Michael R.; Hinch, Scott G.; Brown, Richard S.; Fisk, Aaron

    2013-11-01

    The advent and widespread adoption of electronic tags (including biotelemetry and biologging devices) for tracking animals has provided unprecedented information on the biology, management, and conservation of fish in the world’s oceans and inland waters. However, use of these tools is not without controversy. Even when scientific and management objectives may best be achieved using electronic tags, it is increasingly important to further consider other factors such as the welfare of tagged animals (i.e., the role of training and science-based surgical guidelines, anesthetic use, inability to maintain sterile conditions in field environments), the ethics of tagging threatened species vs. using surrogates, stakeholder perspectives on tagging (including aboriginals), as well as use of data emanating from such studies (e.g., by fishers to facilitate exploitation). Failure to do so will have the potential to create conflict and undermine scientific, management and public confidence in the use of this powerful tool. Indeed, there are already a number of examples of where tracking studies using electronic tags have been halted based on concerns raised by researchers, authorities, or stakeholders. Here we present a candid evaluation of several factors that should be considered when determining when to tag or not to tag fish with electronic devices. It is not our objective to judge the merit of previous studies. Rather, we hope to stimulate debate and discussion regarding the use of electronic tags to study fish. Relatedly, there is a need for more research to address these questions (e.g., what level of cleanliness is needed when conducting surgeries, what type of training should be required for fish surgery) including human dimensions studies to understand perspectives of different actors including society as a whole with respect to tagging and tracking studies.

  12. Surface-Enhanced Raman Spectroscopy

    Indian Academy of Sciences (India)

    IAS Admin

    weak Raman signal, which facilitates identification in chemi- cal and biological systems. Recently, single-molecule Raman scattering has enhanced the detection sensitivity limit of ... was working on the molecular diffraction of light, which ulti-.

  13. Surface-Enhanced Raman Spectroscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 2. Surface-Enhanced Raman Spectroscopy - Recent Advancement of Raman Spectroscopy. Ujjal Kumar Sur. General Article Volume 15 Issue 2 February 2010 pp 154-164 ...

  14. Exploring the Long Tail of Social Media Tags

    NARCIS (Netherlands)

    Kordumova, S.; van Gemert, J.; Snoek, C.G.M.; Tian, Q.; Sebe, N.; Qi, G.-J.; Huet, B.; Hong, R.; Liu, X.

    2016-01-01

    There are millions of users who tag multimedia content, generating a large vocabulary of tags. Some tags are frequent, while other tags are rarely used following a long tail distribution. For frequent tags, most of the multimedia methods that aim to automatically understand audio-visual content,

  15. Development of Raman spectrophotometer

    International Nuclear Information System (INIS)

    Adam, A.I.

    2008-05-01

    In this work, the Raman spectrophotometer HG.2S Jobin Yvon rebuilt and developed, the Raman setup provided as a gift for Neelian University from Amsterdam University. The main parts, which were replaced, include monochromator, an air-cooled photomultiplier tube RCA IP 28, log amplifier, hand scanning lab VIEW card for computer interfacing. The components assembled and the whole device was tested successfully. The developed setup was checked using some standard solutions, which showed perfect consistency with literature in the references and published papers. Solutions included hexane, cyclohexane, carbon tetrachloride, benzene and sodium sulfate.(Author)

  16. Electrochemical Implications of Defects in Carbon Nanotubes

    Science.gov (United States)

    Hall, Jonathan Peter

    The electrochemical behavior of carbon nanotubes (CNTs) containing both intrinsic and extrinsically introduced defects has been investigated through the study of bamboo and hollow multi-walled CNT morphologies. The controlled addition of argon, hydrogen, and chlorine ions in addition to atomic hydrogen and magnesium vapor was used for varying the charge and type of extrinsic defects. To quantify changes in the CNTs upon treatment, Raman spectroscopy and electrochemical techniques were employed. It was indicated from Raman spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and chronopotentiometric experiments that the electrochemical response of hollow type CNTs could be tailored more significantly compared to bamboo type CNTs, which have innately high reactive site densities and are less amenable to modification. Total defect density and edge-plane-like defect concentrations monitored through Raman spectroscopy were used to correlate changes in the electrochemical response of the CNT electrodes as a function of treatment. The implementation of CNT electrodes in a prototypical electrolytic capacitor device was then explored and characterized. Dependencies on source current and redox couple concentration were evaluated, as well as changes in the total capacitance as a function of treatment. Cyclability studies were also performed as a function of source current magnitude to evaluate the longevity of the faradaic currents which typically decrease over time in other similar capacitors. This thesis then concludes with an overall summary of the themes and findings of the research presented in this work.

  17. Defect-Induced Photoluminescence Enhancement and Corresponding Transport Degradation in Individual Suspended Carbon Nanotubes

    Science.gov (United States)

    Wang, Bo; Shen, Lang; Yang, Sisi; Chen, Jihan; Echternach, Juliana; Dhall, Rohan; Kang, DaeJin; Cronin, Stephen

    2018-05-01

    This paper is a contribution to the Physical Review Applied collection in memory of Mildred S. Dresselhaus. The utilization of defects in carbon nanotubes to improve their photoluminescence efficiency has become a widespread study of the realization of efficient light-emitting devices. Here, we report a detailed comparison of the defects in nanotubes (quantified by Raman spectroscopy) and photoluminescence (PL) intensity of individual suspended carbon nanotubes (CNTs). We also evaluate the impact of these defects on the electron or hole transport in the nanotubes, which is crucial for the ultimate realization of optoelectronic devices. We find that brightly luminescent nanotubes exhibit a pronounced D-band in their Raman spectra, and vice versa, dimly luminescent nanotubes exhibit almost no D-band. Here, defects are advantageous for light emission by trapping excitons, which extend their lifetimes. We quantify this behavior by plotting the PL intensity as a function of the ID /IG -band Raman intensity ratio, which exhibits a Lorentzian distribution peaked at ID /IG=0.17 . For CNTs with a ID /IG ratio >0.25 , the PL intensity decreases, indicating that above some critical density, nonradiative recombination at defect sites dominates over the advantages of exciton trapping. In an attempt to fabricate optoelectronic devices based on these brightly luminescent CNTs, we transfer these suspended CNTs to platinum electrodes and find that the brightly photoluminescent nanotubes exhibit nearly infinite resistance due to these defects, while those without bright photoluminescence exhibit finite resistance. These findings indicate a potential limitation in the use of brightly luminescent CNTs for optoelectronic applications.

  18. Method and apparatus for manufacturing gas tags

    International Nuclear Information System (INIS)

    Gross, K.C.; Laug, M.T.

    1996-01-01

    For use in the manufacture of gas tags employed in a gas tagging failure detection system for a nuclear reactor, a plurality of commercial feed gases each having a respective noble gas isotopic composition are blended under computer control to provide various tag gas mixtures having selected isotopic ratios which are optimized for specified defined conditions such as cost. Using a new approach employing a discrete variable structure rather than the known continuous-variable optimization problem, the computer controlled gas tag manufacturing process employs an analytical formalism from condensed matter physics known as stochastic relaxation, which is a special case of simulated annealing, for input feed gas selection. For a tag blending process involving M tag isotopes with N distinct feed gas mixtures commercially available from an enriched gas supplier, the manufacturing process calculates the cost difference between multiple combinations and specifies gas mixtures which approach the optimum defined conditions. The manufacturing process is then used to control tag blending apparatus incorporating tag gas canisters connected by stainless-steel tubing with computer controlled valves, with the canisters automatically filled with metered quantities of the required feed gases. 4 figs

  19. Flavour Tagging Algorithms and Performances in LHCb

    CERN Document Server

    Calvi, M; Musy, M

    2007-01-01

    In this note we describe the general characteristics of the LHCb flavour tagging algorithms and summarize the tagging performances on the Monte Carlo samples generated for the Data Challenge 2004 in different decay channels. We also discuss some systematics effects and possible methods to extract the mistag fraction in real data.

  20. Evaluation of PIT-tagging in cyprinids

    DEFF Research Database (Denmark)

    Skov, Christian; Brodersen, J.; Brönmark, C.

    2005-01-01

    Laboratory and field experiments were used to investigate how different marking procedures, with 23 mm PIT (passive integrated transponders) - tags. affected mortality, body condition and tag expulsion in small roach Rutilus rutilus and rudd Scardinus erythrophthalmus (117 to 163 mm total length...

  1. Tagging behaviour with support from controlled vocabulary

    DEFF Research Database (Denmark)

    Lykke, Marianne; Høj, Anne Lyhne; Madsen, Line Nørgaard

    2011-01-01

    ) and an enhanced tagging system (experimental system) that additionally offers suggestions from the Dewey Decimal Classification system (DDC). In the experimental study twenty-eight political students completed four tagging tasks, each comprising fifteen documents. The focus was to examine how suggestions from...

  2. Synthesis and investigation of PMMA films with homogeneously dispersed multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    Pantoja-Castro, M.A.; Pérez-Robles, J.F.; González-Rodríguez, H.; Vorobiev-Vasilievitch, Y.; Martínez-Tejada, H.V.; Velasco-Santos, C.

    2013-01-01

    Multiwalled carbon nanotubes (MWNT) modified by 2.2′-azoiso-butyronitrile (AIBN) were incorporated into methyl methacrylate (MMA) by sonochemistry method, resulting in homogenous dispersion of MWNT, which makes possible to obtain flexible conductive polymer-matrix nanocomposites films of PMMA, with MWNT concentrations ranging from 0 to 0.5 wt%. Modified MWNT (AIBN-MWNT) were studied by Fourier transform infrared (FT-IR), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and through visual observations in order to compare the dispersion in 2-propanone and toluene with that of pristine MWNT. Synthesized PMMA-AIBN-MWNT films were studied by FT-IR and Raman spectroscopy. Using FT-IR for the AIBN-MWNT it was not possible to identify any group or groups attached to the nanotubes. Raman spectroscopy shows a small modification in the Lorentzian peaks ratio I D/G of AIBN-MWNT, meanwhile XPS showed that atomic compositions does not change for AIBN-MWNT compared to the pristine nanotubes. Also by impedance it was analyzed the conductivity of PMMA-MWNT films and the results showed a threshold percolation at 0.5 wt%. FT-IR and Raman analyses for PMMA-AIBN-MWNT composite indicate a covalent bonding between PMMA and MWNT due to the opening of π-bonds of the nanotubes, which is related with a possible proposed reaction scheme. - Graphical abstract: Display Omitted - Highlights: • We used sonochemistry-in situ polymerization to disperse MWNT very soon in PMMA. • A high and homogenous dispersion of MWNT in PMMA was achieved. • The modification of MWNT by AIBN was analyzed using Raman. • A covalent bonding between PMMA and MWNT was analyzed by FT-IR and Raman. • According to the results of PMMA-MWNT it was proposed a scheme reaction

  3. Synthesis and investigation of PMMA films with homogeneously dispersed multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Pantoja-Castro, M.A., E-mail: m_pantojaq@yahoo.com.mx [Facultad de Ingeniería Química, Universidad Michoacana de San Nicolás de Hidalgo, Av. J. Múgica S/N Col., Villa Universidad, CP 58040 Morelia, Michoacán (Mexico); Pérez-Robles, J.F. [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro, Libramiento Norponiente #2000, Fracc. Real de Juriquilla, CP 76230 Querétaro (Mexico); González-Rodríguez, H. [Facultad de Ingeniería Química, Universidad Michoacana de San Nicolás de Hidalgo, Av. J. Múgica S/N Col., Villa Universidad, CP 58040 Morelia, Michoacán (Mexico); Vorobiev-Vasilievitch, Y. [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro, Libramiento Norponiente #2000, Fracc. Real de Juriquilla, CP 76230 Querétaro (Mexico); Martínez-Tejada, H.V. [Instituto de Energía, Materiales y Medio Ambiente, Universidad Pontificia Bolivariana, Circular 1 No. 70-01, Bloque 22, Medellín (Colombia); Velasco-Santos, C. [Centro de Física Aplicada y Tecnología Avanzada, Universidad Autónoma de México, Av. Boulevard Juriquilla, No. 3001 Juriquilla, CP 76230 Querétaro (Mexico)

    2013-07-15

    Multiwalled carbon nanotubes (MWNT) modified by 2.2′-azoiso-butyronitrile (AIBN) were incorporated into methyl methacrylate (MMA) by sonochemistry method, resulting in homogenous dispersion of MWNT, which makes possible to obtain flexible conductive polymer-matrix nanocomposites films of PMMA, with MWNT concentrations ranging from 0 to 0.5 wt%. Modified MWNT (AIBN-MWNT) were studied by Fourier transform infrared (FT-IR), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and through visual observations in order to compare the dispersion in 2-propanone and toluene with that of pristine MWNT. Synthesized PMMA-AIBN-MWNT films were studied by FT-IR and Raman spectroscopy. Using FT-IR for the AIBN-MWNT it was not possible to identify any group or groups attached to the nanotubes. Raman spectroscopy shows a small modification in the Lorentzian peaks ratio I{sub D/G} of AIBN-MWNT, meanwhile XPS showed that atomic compositions does not change for AIBN-MWNT compared to the pristine nanotubes. Also by impedance it was analyzed the conductivity of PMMA-MWNT films and the results showed a threshold percolation at 0.5 wt%. FT-IR and Raman analyses for PMMA-AIBN-MWNT composite indicate a covalent bonding between PMMA and MWNT due to the opening of π-bonds of the nanotubes, which is related with a possible proposed reaction scheme. - Graphical abstract: Display Omitted - Highlights: • We used sonochemistry-in situ polymerization to disperse MWNT very soon in PMMA. • A high and homogenous dispersion of MWNT in PMMA was achieved. • The modification of MWNT by AIBN was analyzed using Raman. • A covalent bonding between PMMA and MWNT was analyzed by FT-IR and Raman. • According to the results of PMMA-MWNT it was proposed a scheme reaction.

  4. Notes on SAW Tag Interrogation Techniques

    Science.gov (United States)

    Barton, Richard J.

    2010-01-01

    We consider the problem of interrogating a single SAW RFID tag with a known ID and known range in the presence of multiple interfering tags under the following assumptions: (1) The RF propagation environment is well approximated as a simple delay channel with geometric power-decay constant alpha >/= 2. (2) The interfering tag IDs are unknown but well approximated as independent, identically distributed random samples from a probability distribution of tag ID waveforms with known second-order properties, and the tag of interest is drawn independently from the same distribution. (3) The ranges of the interfering tags are unknown but well approximated as independent, identically distributed realizations of a random variable rho with a known probability distribution f(sub rho) , and the tag ranges are independent of the tag ID waveforms. In particular, we model the tag waveforms as random impulse responses from a wide-sense-stationary, uncorrelated-scattering (WSSUS) fading channel with known bandwidth and scattering function. A brief discussion of the properties of such channels and the notation used to describe them in this document is given in the Appendix. Under these assumptions, we derive the expression for the output signal-to-noise ratio (SNR) for an arbitrary combination of transmitted interrogation signal and linear receiver filter. Based on this expression, we derive the optimal interrogator configuration (i.e., transmitted signal/receiver filter combination) in the two extreme noise/interference regimes, i.e., noise-limited and interference-limited, under the additional assumption that the coherence bandwidth of the tags is much smaller than the total tag bandwidth. Finally, we evaluate the performance of both optimal interrogators over a broad range of operating scenarios using both numerical simulation based on the assumed model and Monte Carlo simulation based on a small sample of measured tag waveforms. The performance evaluation results not only

  5. The effect of different temperature profiles upon the length and crystallinity of vertically-aligned multi-walled carbon nanotubes.

    Science.gov (United States)

    Yun, Jongju; Lee, Cheesung; Zheng, Qing; Baik, Seunghyun

    2012-08-01

    We synthesized vertically-aligned multi-walled carbon nanotubes with an inner diameter of 1.6-7.5 nm and stack height of 80-28600 microm by chemical vapor deposition. The effects of synthesis conditions such as substrate position in the tube furnace, maximum temperature, temperature increasing rate and synthesis duration on the structure of nanotubes were investigated. It was found that slightly faster temperature increase rate resulted in significantly longer length, larger diameter and more defects of nanotubes. Structural parameters such as inner, outer diameters, wall thickness and defects were investigated using transmission electron microscopy and Raman spectroscopy.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  7. Catalyst Design Using Nanoporous Iron for the Chemical Vapor Deposition Synthesis of Single-Walled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Tarek M. Abdel-Fattah

    2013-01-01

    Full Text Available Single-walled carbon nanotubes (SWNTs have been synthesized via a novel chemical vapor deposition (CVD approach utilizing nanoporous, iron-supported catalysts. Stable aqueous dispersions of the CVD-grown nanotubes using an anionic surfactant were also obtained. The properties of the as-produced SWNTs were characterized through atomic force microscopy and Raman spectroscopy and compared with purified SWNTs produced via the high-pressure CO (HiPCO method as a reference, and the nanotubes were observed with greater lengths than those of similarly processed HiPCO SWNTs.

  8. Sentiment topic mining based on comment tags

    Science.gov (United States)

    Zhang, Daohai; Liu, Xue; Li, Juan; Fan, Mingyue

    2018-03-01

    With the development of e-commerce, various comments based on tags are generated, how to extract valuable information from these comment tags has become an important content of business management decisions. This study takes HUAWEI mobile phone tags as an example using the sentiment analysis and topic LDA mining method. The first step is data preprocessing and classification of comment tag topic mining. And then make the sentiment classification for comment tags. Finally, mine the comments again and analyze the emotional theme distribution under different sentiment classification. The results show that HUAWEI mobile phone has a good user experience in terms of fluency, cost performance, appearance, etc. Meanwhile, it should pay more attention to independent research and development, product design and development. In addition, battery and speed performance should be enhanced.

  9. Raman spectra of graphene ribbons

    International Nuclear Information System (INIS)

    Saito, R; Furukawa, M; Dresselhaus, G; Dresselhaus, M S

    2010-01-01

    Raman spectra of graphene nanoribbons with zigzag and armchair edges are calculated within non-resonant Raman theory. Depending on the edge structure and polarization direction of the incident and scattered photon beam relative to the edge direction, a symmetry selection rule for the phonon type appears. These Raman selection rules will be useful for the identification of the edge structure of graphene nanoribbons.

  10. Tip-enhanced Raman mapping with top-illumination AFM.

    Science.gov (United States)

    Chan, K L Andrew; Kazarian, Sergei G

    2011-04-29

    Tip-enhanced Raman mapping is a powerful, emerging technique that offers rich chemical information and high spatial resolution. Currently, most of the successes in tip-enhanced Raman scattering (TERS) measurements are based on the inverted configuration where tips and laser are approaching the sample from opposite sides. This results in the limitation of measurement for transparent samples only. Several approaches have been developed to obtain tip-enhanced Raman mapping in reflection mode, many of which involve certain customisations of the system. We have demonstrated in this work that it is also possible to obtain TERS nano-images using an upright microscope (top-illumination) with a gold-coated Si atomic force microscope (AFM) cantilever without significant modification to the existing integrated AFM/Raman system. A TERS image of a single-walled carbon nanotube has been achieved with a spatial resolution of ∼ 20-50 nm, demonstrating the potential of this technique for studying non-transparent nanoscale materials.

  11. Tip-enhanced Raman mapping with top-illumination AFM

    Energy Technology Data Exchange (ETDEWEB)

    Chan, K L Andrew; Kazarian, Sergei G, E-mail: s.kazarian@imperial.ac.uk [Department of Chemical Engineering, Imperial College London, SW7 2AZ (United Kingdom)

    2011-04-29

    Tip-enhanced Raman mapping is a powerful, emerging technique that offers rich chemical information and high spatial resolution. Currently, most of the successes in tip-enhanced Raman scattering (TERS) measurements are based on the inverted configuration where tips and laser are approaching the sample from opposite sides. This results in the limitation of measurement for transparent samples only. Several approaches have been developed to obtain tip-enhanced Raman mapping in reflection mode, many of which involve certain customisations of the system. We have demonstrated in this work that it is also possible to obtain TERS nano-images using an upright microscope (top-illumination) with a gold-coated Si atomic force microscope (AFM) cantilever without significant modification to the existing integrated AFM/Raman system. A TERS image of a single-walled carbon nanotube has been achieved with a spatial resolution of {approx} 20-50 nm, demonstrating the potential of this technique for studying non-transparent nanoscale materials.

  12. Tip-enhanced Raman mapping with top-illumination AFM

    International Nuclear Information System (INIS)

    Chan, K L Andrew; Kazarian, Sergei G

    2011-01-01

    Tip-enhanced Raman mapping is a powerful, emerging technique that offers rich chemical information and high spatial resolution. Currently, most of the successes in tip-enhanced Raman scattering (TERS) measurements are based on the inverted configuration where tips and laser are approaching the sample from opposite sides. This results in the limitation of measurement for transparent samples only. Several approaches have been developed to obtain tip-enhanced Raman mapping in reflection mode, many of which involve certain customisations of the system. We have demonstrated in this work that it is also possible to obtain TERS nano-images using an upright microscope (top-illumination) with a gold-coated Si atomic force microscope (AFM) cantilever without significant modification to the existing integrated AFM/Raman system. A TERS image of a single-walled carbon nanotube has been achieved with a spatial resolution of ∼ 20-50 nm, demonstrating the potential of this technique for studying non-transparent nanoscale materials.

  13. Tagged at first listen: an examination of social tagging practices in a music recommender system

    Directory of Open Access Journals (Sweden)

    Audrey Laplante

    2015-01-01

    Full Text Available http://dx.doi.org/10.5007/1518-2924.2015v20nesp1p33 Social tagging has become a very common way to index different types of resources on the web. Less prevalent in music than in other domains, social tagging is nevertheless used in a popular recommender system, Last.fm. Although the number of publications on tagging and folksonomies has exploded in the last few years, music tagging is still not well studied. In this paper, we present a study of tagging practices of Last.fm users. We examine the social tagging of songs during the first three months after their release. Our analysis shows that the release of a song triggers a burst in tagging activity that lasts two weeks, after what it decreases sharply and then remains fairly constant for the next ten weeks. We also find that a majority of songs do not get tagged during the first week and that tagging was positively related to popularity. Finally, we find that tags that have been frequently applied to a given song are more likely to be genre related, shorter in length, and relatively objective than tags that have been applied only once.

  14. Indium telluride nanotubes: Solvothermal synthesis, growth mechanism, and properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Liyan [National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Yan, Shancheng, E-mail: yansc@njupt.edu.cn [National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Lu, Tao; Shi, Yi; Wang, Jianyu [National Laboratory of Solid State Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Yang, Fan [School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China)

    2014-03-15

    A convenient solvothermal approach was applied for the first time to synthesize In{sub 2}Te{sub 3} nanotubes. The morphology of the resultant nanotubes was studied by scanning electron microscopy and transmission electron microscopy. Nanotubes with a relatively uniform diameter of around 500 nm, tube wall thickness of 50–100 nm, and average length of tens of microns were obtained. X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to study the crystal structures, composition, and optical properties of the products. To understand the growth mechanism of the In{sub 2}Te{sub 3} nanotubes, we studied the influences of temperature, reaction time, and polyvinylpyrrolidone (PVP) and ethylene diamine (EDA) dosages on the final products. Based on the experimental results, a possible growth mechanism of In{sub 2}Te{sub 3} nanotubes was proposed. In this mechanism, TeO{sub 3}{sup −2} is first reduced to allow nucleation. Circumferential edges of these nucleated molecules attract further deposition, and nanotubes finally grow rapidly along the c-axis and relatively slowly along the circumferential direction. The surface area of the products was determined by BET and found to be 137.85 m{sup 2} g{sup −1}. This large surface area indicates that the nanotubes may be suitable for gas sensing and hydrogen storage applications. The nanotubes also showed broad light detection ranging from 300 nm to 1100 nm, which covers the UV–visible–NIR regions. Such excellent optical properties indicate that In{sub 2}Te{sub 3} nanotubes may enable significant advancements in new photodetection and photosensing applications. -- Graphical abstract: A convenient solvothermal approach was applied to synthesize In{sub 2}Te{sub 3} nanotubes, which has not been reported in the literature for our knowledge. Surface area of this material is 137.85 m{sup 2} g{sup −1} from the BET testing, and such a high value makes it probably suitable for gas sensing and

  15. Designing of Raman laser

    International Nuclear Information System (INIS)

    Zidan, M. D.; Al-Awad, F.; Alsous, M. B.

    2005-01-01

    In this work, we describe the design of the Raman laser pumped by Frequency doubled Nd-YAG laser (λ=532 nm) to generate new laser wavelengths by shifting the frequency of the Nd-YAG laser to Stokes region (λ 1 =683 nm, λ 2 =953.6 nm, λ 3 =1579.5 nm) and Antistokes region (λ ' 1 =435 nm, λ ' 2 =369.9 nm, λ ' 3=319.8 nm). Laser resonator has been designed to increase the laser gain. It consists of two mirrors, the back mirror transmits the pump laser beam (λ=532 nm) through the Raman tube and reflects all other generated Raman laser lines. Four special front mirrors were made to be used for the four laser lines λ 1 =683 nm, λ 2 =953.6 nm and λ ' 1 = 435 nm, λ ' 2 =369.9 nm. The output energy for the lines υ 1 s, υ 2 s, υ 1 as,υ 2 as was measured. The output energy of the Raman laser was characterized for different H 2 pressure inside the tube. (Author)

  16. Confocal Raman microspectroscopy

    International Nuclear Information System (INIS)

    Puppels, G.J.

    1991-01-01

    Raman spectroscopy is a technique that provides detailed structural information about molecules studied. In the field of molecular biophysics it has been extensively used for characterization of nucleic acids and proteins and for investigation of interactions between these molecules. It was felt that this technique would have great potential if it could be applied for in situ study of these molecules and their interactions, at the level of single living cell or a chromosome. To make this possible a highly sensitive confocal Raman microspectrometer (CRM) was developed. The instrument is described in detail in this thesis. It incorporates a number of recent technological developments. First, it employs a liquid nitrogen cooled CCD-camera. This type of detector, first used in astronomy, is the ultimate detector for Raman spectroscopy because it combines high quantum efficiency light detection with photon-noise limited operation. Second, an important factor in obtaining a high signal throughput of the spectrometer was the development of a new type of Raman notch filter. In the third place, the confocal detection principle was applied in the CRM. This limits the effective measuring volume to 3 . (author). 279 refs., 48 figs., 11 tabs

  17. The stability of halloysite nanotubes in acidic and alkaline aqueous suspensions

    International Nuclear Information System (INIS)

    White, Rachel D; Bavykin, Dmitry V; Walsh, Frank C

    2012-01-01

    The long term stability of natural halloysite nanotubes was studied at room temperature (22 ± 2 °C) in pure water, acidic and basic aqueous suspensions. The structural and morphological transformations of nanotubes were studied by TEM, SEM, nitrogen adsorption, XRD Raman and FTIR spectroscopy accompanied by monitoring the concentration of dissolved Si(IV) and Al(III) in solution. It has been revealed that, in 1 mol dm −3 H 2 SO 4 solution, the dissolution of halloysite is initiated on the inner surface of nanotubes, leading to the formation of amorphous spheroidal nanoparticles of SiO 2 whereas, in 1 mol dm −3 NaOH solution, dissolution of the inner surface of nanotubes is accompanied by the formation of Al(OH) 3 nanosheets. (paper)

  18. Thermal conductivity of vertically aligned carbon nanotube arrays: Growth conditions and tube inhomogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Matthew L.; Pham, Quang N.; Saltonstall, Christopher B.; Norris, Pamela M. [Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904-4746 (United States)

    2014-10-13

    The thermal conductivity of vertically aligned carbon nanotube arrays (VACNTAs) grown on silicon dioxide substrates via chemical vapor deposition is measured using a 3ω technique. For each sample, the VACNTA layer and substrate are pressed to a heating line at varying pressures to extract the sample's thermophysical properties. The nanotubes' structure is observed via transmission electron microscopy and Raman spectroscopy. The presence of hydrogen and water vapor in the fabrication process is tuned to observe the effect on measured thermal properties. The presence of iron catalyst particles within the individual nanotubes prevents the array from achieving the overall thermal conductivity anticipated based on reported measurements of individual nanotubes and the packing density.

  19. Field emission response from multi-walled carbon nanotubes grown on electrochemically engineered copper foil

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, Amit Kumar; Jain, Vaibhav [Nanomaterials and Applications Lab., Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand (India); Saini, Krishna [Nanomaterials and Applications Lab., Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand (India); Centre of Excellence: Nanotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand (India); Lahiri, Indranil, E-mail: indrafmt@iitr.ac.in [Nanomaterials and Applications Lab., Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand (India); Centre of Excellence: Nanotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand (India)

    2017-02-01

    Exciting properties of carbon nanotube has proven it to be a promising candidate for field emission applications, if its processing cost can be reduced effectively. In this research, a new electrochemical technique is proposed for growing carbon nanotubes in selective areas by thermal chemical vapour deposition. In this process, electrochemical processing is used to create localized pits and deposition of catalysts, which act as roots to support growth and alignment of the CNTs on copper substrate. CNTs grown thus were characterized and studied using scanning electron microscope, transmission electron microscope and Raman spectroscopy, elucidating presence of multiwall carbon nanotubes (MWCNT). These CNT emitters have comparatively lower turn-on field and higher field enhancement factor. - Highlights: • Electrochemical pitting for localized carbon nanotube growth is proposed. • Electrochemical pitting method shows patterning effect on the substrate. • Size and density of pits depend on voltage, pH and temperature. • CNTs thus grown shows good field emission response.

  20. An efficient route towards the covalent functionalization of single walled carbon nanotubes

    International Nuclear Information System (INIS)

    Kakade, Bhalchandra A.; Pillai, Vijayamohanan K.

    2008-01-01

    A simple and efficient method of chemical functionalization of both single and multiwalled carbon nanotubes has been discussed to give enhanced water solubility by rapidly and efficiently generating an appreciable amount of hydrophilic functional groups using microwave radiation. Surface functionalization containing more than 30 wt% of oxygen has been achieved, resulting into solubility of 2-5 mg/mL. Further covalent functionalization of such soluble SWNTs provides a remarkable degree of aniline functionalization through amidation, where the formation of polyaniline has been avoided. Functionalization of SWNTs is confirmed by techniques like electron microscopy, Fourier transform infrared spectroscopy, thermogravimetry, Raman spectroscopy, cyclic voltammetry and impedance spectroscopy. Electrochemical analysis suggests an enhanced double layer capacitance (∼110 F/g) of nanotubes after microwave treatment. Aniline functionalization of SWNTs shows possible variations on the nanotube topography with concomitant formation of a dynamic polymer layer on the nanotube surface

  1. Multiwalled carbon nanotube destruction in the radiation damages to electron irradiation

    Directory of Open Access Journals (Sweden)

    T. M. Pinchuk-Rugal’

    2015-10-01

    Full Text Available Behavior of the X-ray diffraction and vibrational Raman spectra of multiwalled carbon nanotubes (MWCNT under high-energy electron irradiation (Ee = 1.8 MeV with large doses of absorption to 10 MGy were studied. With increasing dose uptake to 10.0 MGy, the interlayer correlation in the distribution of the individual graphene nanotubes nets not only is maintained, but is even improved. Defective bands D, D' and G band with increasing dose absorption have significant transformation, which show radiation damages of MWCNT. The destruction of nanotubes under electron irradiation is accompanied by increased regulation in the arrangement of individual nanotubes by interlayer cross-links involving interstitial atoms. The severity of degradation and cross-linking of MWCNT depends on the electron absorption dose.

  2. Pop-up Archival Transmitting (PAT) fish tag data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The cooperative tagging center (CTC) began deploying electronic tags in 2002. To date over 300 tags have been deployed. The following species have been monitored:...

  3. Raman Imaging Techniques and Applications

    CERN Document Server

    2012-01-01

    Raman imaging has long been used to probe the chemical nature of a sample, providing information on molecular orientation, symmetry and structure with sub-micron spatial resolution. Recent technical developments have pushed the limits of micro-Raman microscopy, enabling the acquisition of Raman spectra with unprecedented speed, and opening a pathway to fast chemical imaging for many applications from material science and semiconductors to pharmaceutical drug development and cell biology, and even art and forensic science. The promise of tip-enhanced raman spectroscopy (TERS) and near-field techniques is pushing the envelope even further by breaking the limit of diffraction and enabling nano-Raman microscopy.

  4. [Three-dimensional vertically aligned CNTs coated by Ag nanoparticles for surface-enhanced Raman scattering].

    Science.gov (United States)

    Zhang, Xiao-Lei; Zhang, Jie; Fan, Tuo; Ren, Wen-Jie; Lai, Chun-Hong

    2014-09-01

    In order to make surface-enhanced Raman scattering (SERS) substrates contained more "hot spots" in a three-dimensional (3D) focal volume, and can be adsorbed more probe molecules and metal nanoparticles, to obtain stronger Raman spectral signal, a new structure based on vertically aligned carbon nanotubes (CNTs) coated by Ag nanoparticles for surface Raman enhancement is presented. The vertically aligned CNTs are synthesized by chemical vapor deposition (CVD). A silver film is first deposited on the vertically aligned CNTs by magnetron sputtering. The samples are then annealed at different temperature to cause the different size silver nanoparticles to coat on the surface and sidewalls of vertically aligned CNTs. The result of scanning electron microscopy(SEM) shows that Ag nanoparticles are attached onto the sidewalls and tips of the vertically aligned CNTs, as the annealing temperature is different , pitch size, morphology and space between the silver nanoparticles is vary. Rhodamine 6G is served as the probe analyte. Raman spectrum measurement indicates that: the higher the concentration of R6G, the stronger the Raman intensity, but R6G concentration increase with the enhanced Raman intensity varies nonlinearly; when annealing temperature is 450 °C, the average size of silver nanoparticles is about 100 to 120 nm, while annealing temperature is 400 °C, the average size is about 70 nm, and the Raman intensity of 450 °C is superior to the annealing temperature that of 400 °C and 350 °C.

  5. DICOM involving XML path-tag

    Science.gov (United States)

    Zeng, Qiang; Yao, Zhihong; Liu, Lei

    2011-03-01

    Digital Imaging and Communications in Medicine (DICOM) is a standard for handling, storing, printing, and transmitting information in medical imaging. XML (Extensible Markup Language) is a set of rules for encoding documents in machine-readable form which has become more and more popular. The combination of these two is very necessary and promising. Using XML tags instead of numeric labels in DICOM files will effectively increase the readability and enhance the clear hierarchical structure of DICOM files. However, due to the fact that the XML tags rely heavily on the orders of the tags, the strong data dependency has a lot of influence on the flexibility of inserting and exchanging data. In order to improve the extensibility and sharing of DICOM files, this paper introduces XML Path-Tag to DICOM. When a DICOM file is converted to XML format, adding simple Path-Tag into the DICOM file in place of complex tags will keep the flexibility of a DICOM file while inserting data elements and give full play to the advantages of the structure and readability of an XML file. Our method can solve the weak readability problem of DICOM files and the tedious work of inserting data into an XML file. In addition, we set up a conversion engine that can transform among traditional DICOM files, XML-DCM and XML-DCM files involving XML Path-Tag efficiently.

  6. Raman spectroscopy an intensity approach

    CERN Document Server

    Guozhen, Wu

    2017-01-01

    This book summarizes the highlights of our work on the bond polarizability approach to the intensity analysis. The topics covered include surface enhanced Raman scattering, Raman excited virtual states and Raman optical activity (ROA). The first chapter briefly introduces the Raman effect in a succinct but clear way. Chapter 2 deals with the normal mode analysis. This is a basic tool for our work. Chapter 3 introduces our proposed algorithm for the Raman intensity analysis. Chapter 4 heavily introduces the physical picture of Raman virtual states. Chapter 5 offers details so that the readers can have a comprehensive idea of Raman virtual states. Chapter 6 demonstrates how this bond polarizability algorithm is extended to ROA intensity analysis. Chapters 7 and 8 offer details on ROA, showing many findings on ROA mechanism that were not known or neglected before. Chapter 9 introduces our proposed classical treatment on ROA which, as combined with the results from the bond polarizability analysis, leads to a com...

  7. Folksonomia: a linguagem das tags

    Directory of Open Access Journals (Sweden)

    Juliana de Assis

    2013-01-01

    Full Text Available A radicalização do potencial colaborativo da web atual aponta uma tendência de personalização da recuperação da informação através de ferramentas que exploram a linguagem natural na representação e no compartilhamento de conteúdos ao longo das redes sociais. Tal configuração sócio-técnica traz desafios aos profissionais da informação tanto para a descrição e compreensão dos fenômenos informacionais que ocorrem neste âmbito, quanto para a elaboração de produtos e serviços voltados para um usuário que se apresenta cada vez mais como sujeito informacional ao assumir um papel ativo diante da complexidade que caracteriza a organização da informação em contextos digitais. Este artigo apresenta conclusões de pesquisa, relacionadas às analises da linguagem utilizada em três ambientes colaborativos que utilizam a folksonomia (Social Tagging Systems. A partir de uma perspectiva fundamentada na Semiótica e na Análise de Redes Sociais, são identificadas e descritas as principais manifestações da linguagem gerada e compartilhada pelas redes sociais através destes ambientes.

  8. Preparation of carbon nanotubes by MPECVD

    International Nuclear Information System (INIS)

    El-Shazly Duraia, M.A.; Mansorov, Z.A.; Tokmoldin, S.Zh.; Klimenov, V.V.; Nevmerzhitsky, I.S.; Dochshanov, A.M.

    2009-01-01

    Microwave plasma-enhanced chemical vapor deposition (MPECVD) method has been regarded as one of the most promising candidates for the synthesis of CNTs due to the vertical alignment, the large area growth, the lower growth temperature, uniform heat distribution and the good control of the different growth parameters. In this work we present our results about the preparation of carbon nanotube with different morphologies by using microwave plasma enhanced chemical vapor deposition MPECVD. Well aligned, curly and coiled carbon nanotubes have been prepared. We have investigated the effect of the different growth condition parameters such as type of the catalyst, pressure and the hydrogen to methane flow rate ratio on the morphology of the carbon nanotubes. The results were showed that there is a great dependence of the morphology of carbon nanotubes on these parameters. There is a linear relation between the growth rate and the methane to hydrogen ratio. We found that the growth rate has a great dependence on the amount of methane. For example the growth rate varied from the value 1,34 μm/min when the methane flow rate was 10 sccm to more than 14 μm/min when the methane flow rate was raised to 50 sccm. This growth rate is greater than that reported in the literature. The effect of the gas pressure on the CNTs was also studied. The Raman spectra (excitation wavelength 473 nm) of all samples show D-band peak at around 1300 cm -1 and G-band peak at around 1580 cm -1 , which indicate that our CNTs are multi wall CNTs (MWCNTs). The D-band and the G-band correspond to sp 2 and sp 3 carbon stretching modes relatively, and their intensity ratio is a measure of the amount of disorder in the CNTs. The D-band is known to be attributed to the carbonaceous particles, defects in the curved graphitic sheet and tube ends. It has been suggested that lower I g /I d ratios and narrower first and second order D and G bands are suggestive of well-aligned NNTs. The photoluminescence PL

  9. Surface-enhanced Raman scattering based nonfluorescent probe for multiplex DNA detection.

    Science.gov (United States)

    Sun, Lan; Yu, Chenxu; Irudayaraj, Joseph

    2007-06-01

    To provide rapid and accurate detection of DNA markers in a straightforward, inexpensive, and multiplex format, an alternative surface-enhanced Raman scattering based probe was designed and fabricated to covalently attach both DNA probing sequence and nonfluorescent Raman tags to the surface of gold nanoparticles (DNA-AuP-RTag). The intensity of Raman signal of the probes could be controlled through the surface coverage of the nonfluorescent Raman tags (RTags). Detection sensitivity of these probes could be optimized by fine-tuning the amount of DNA molecules and RTags on the probes. Long-term stability of the DNA-AuP-RTag probes was found to be good (over 3 months). Excellent multiplexing capability of the DNA-AuP-RTag scheme was demonstrated by simultaneous identification of up to eight probes in a mixture. Detection of hybridization of single-stranded DNA to its complementary targets was successfully accomplished with a long-term goal to use nonfluorescent RTags in a Raman-based DNA microarray platform.

  10. W/Top/Higgs-tagging in ATLAS

    CERN Document Server

    Norjoharuddeen, Nurfikri; The ATLAS collaboration

    2017-01-01

    We present updates of W, Top and Higgs tagging studies with the ATLAS detector. The performance of 2 variable taggers, HEPTopTagger and shower deconstruction are compared in Monte Carlo simulations. To asses the modelling of the taggers’ performance, the tagging efficiencies are measured, with the full 2015+2016 dataset, in semi-leptonic top quark pair events and the background rejections are measured in dijet and photon+jet topologies. Recent developments in subjet reconstruction techniques for high transverse momentum Higgs->bb tagging are also presented.

  11. Improving the wettability of aluminum on carbon nanotubes

    International Nuclear Information System (INIS)

    So, Kang Pyo; Lee, Il Ha; Duong, Dinh Loc; Kim, Tae Hyung; Lim, Seong Chu; An, Kay Hyeok; Lee, Young Hee

    2011-01-01

    Research highlights: → The wettability of CNT in Al metal was improved by electroplating method. → This involves two steps: (i) Al electroplating and (ii) additional Al wetting. → The large surface tension difference was overcome by forming Al-C covalent bonds. → Al-C covalent bond was verified by Raman spectroscopy and XPS. → Density functional calculations confirmed structural model of CNT-vacancy-O-Al. - Abstract: The wetting of a metal on carbon nanotubes is fundamentally difficult due to the unusually large difference between their surface tensions and is a bottleneck for making metal-carbon nanotube (CNT) composites. Here, we report a simple method to enhance the wettability of metal particles on the CNT surface by applying aluminum, which is the material with the largest surface tension. This method involves two steps: (i) Al nanoparticles are decorated on multiwalled carbon nanotubes by electroplating and (ii) Al powder is further spread on Al-electroplated CNTs, followed by high-temperature annealing to accommodate complete wetting of the aluminum. The large surface tension difference is overcome by forming strong Al-C covalent bonds initiated by defects of the CNTs. The decrease in the D-band intensity, the G-band shift in the Raman spectroscopy and the formation of Al-C covalent bonds, as confirmed by X-ray photoelectron spectroscopy, were in agreement with our structural model of CNT-vacancy-O-Al determined by density functional calculations.

  12. Nanotube resonator devices

    Science.gov (United States)

    Jensen, Kenneth J; Zettl, Alexander K; Weldon, Jeffrey A

    2014-05-06

    A fully-functional radio receiver fabricated from a single nanotube is being disclosed. Simultaneously, a single nanotube can perform the functions of all major components of a radio: antenna, tunable band-pass filter, amplifier, and demodulator. A DC voltage source, as supplied by a battery, can power the radio. Using carrier waves in the commercially relevant 40-400 MHz range and both frequency and amplitude modulation techniques, successful music and voice reception has been demonstrated. Also disclosed are a radio transmitter and a mass sensor using a nanotube resonator device.

  13. Effective transformation of PCDTBT nanorods into nanotubes by polymer melts wetting approach

    Directory of Open Access Journals (Sweden)

    Fakhra Aziz

    2017-09-01

    Full Text Available In the present study, p-type conducting polymer of poly [N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole] (PCDTBT has been explored for nanostructures. A novel approach has been adopted to transform nanorods into nanotubes by altering template-wetting methods. PCDTBT nanorods are fabricated by infiltrating porous alumina template with various solution concentrations of 5, 10 and 15 mg/ml. Upon thermal annealing PCDTBT beyond its melting point, the nanorods are transformed into nanotubes. The morphological and optical investigations reveal that the nanorods prepared with a concentration of 10 mg/ml are longer, denser, well-arranged and red shifted as compared to other nanorods. The PCDTBT nanotubes of the same concentration prepared at 300 °C are found the best among all other nanotubes with improved length, density and alignment as compared to their nanorod counterparts. Furthermore, the optical spectra of the nanotubes demonstrate broad spectral region, augmented absorption intensity and significant red-shift. The changes observed in Raman shift indicate improvement in molecular arrangement of the nanotubes. Optimization of the solution concentration and annealing temperature leads to improvement of PCDTBT nanostructures. PCDTBT nanotubes, with better molecular arrangement and broad optical spectrum, can be exploited in the state-of-the-art photovoltaic devices.

  14. Electrochemical synthesis of self-organized TiO2 crystalline nanotubes without annealing

    Science.gov (United States)

    Giorgi, Leonardo; Dikonimos, Theodoros; Giorgi, Rossella; Buonocore, Francesco; Faggio, Giuliana; Messina, Giacomo; Lisi, Nicola

    2018-03-01

    This work demonstrates that upon anodic polarization in an aqueous fluoride-containing electrolyte, TiO2 nanotube array films can be formed with a well-defined crystalline phase, rather than an amorphous one. The crystalline phase was obtained avoiding any high temperature annealing. We studied the formation of nanotubes in an HF/H2O medium and the development of crystalline grains on the nanotube wall, and we found a facile way to achieve crystalline TiO2 nanotube arrays through a one-step anodization. The crystallinity of the film was influenced by the synthesis parameters, and the optimization of the electrolyte composition and anodization conditions (applied voltage and time) were carried out. For comparison purposes, crystalline anatase TiO2 nanotubes were also prepared by thermal treatment of amorphous nanotubes grown in an organic bath (ethylene glycol/NH4F/H2O). The morphology and the crystallinity of the nanotubes were studied by field emission gun-scanning electron microscopy (FEG-SEM) and Raman spectroscopy, whereas the electrochemical and semiconducting properties were analyzed by means of linear sweep voltammetry, impedance spectroscopy, and Mott-Schottky plots. X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) allowed us to determine the surface composition and the electronic structure of the samples and to correlate them with the electrochemical data. The optimal conditions to achieve a crystalline phase with high donor concentration are defined.

  15. Transparent and Electrically Conductive Carbon Nanotube-Polymer Nanocomposite Materials for Electrostatic Charge Dissipation

    Science.gov (United States)

    Dervishi, E.; Biris, A. S.; Biris, A. R.; Lupu, D.; Trigwell, S.; Miller, D. W.; Schmitt, T.; Buzatu, D. A.; Wilkes, J. G.

    2006-01-01

    In recent years, nanocomposite materials have been extensively studied because of their superior electrical, magnetic, and optical properties and large number of possible applications that range from nano-electronics, specialty coatings, electromagnetic shielding, and drug delivery. The aim of the present work is to study the electrical and optical properties of carbon nanotube(CNT)-polymer nanocomposite materials for electrostatic charge dissipation. Single and multi-wall carbon nanotubes were grown by catalytic chemical vapor deposition (CCVD) on metal/metal oxide catalytic systems using acetylene or other hydrocarbon feedstocks. After the purification process, in which amorphous carbon and non-carbon impurities were removed, the nanotubes were functionalized with carboxylic acid groups in order to achieve a good dispersion in water and various other solvents. The carbon nanostructures were analyzed, both before and after functionalization by several analytical techniques, including microscopy, Raman spectroscopy, and X-Ray photoelectron spectroscopy. Solvent dispersed nanotubes were mixed (1 to 7 wt %) into acrylic polymers by sonication and allowed to dry into 25 micron thick films. The electrical and optical properties of the films were analyzed as a function of the nanotubes' concentration. A reduction in electrical resistivity, up to six orders of magnitude, was measured as the nanotubes' concentration in the polymeric films increased, while optical transparency remained 85 % or higher relative to acrylic films without nanotubes.

  16. Optical spectroscopy of iodine-doped single-wall carbon nanotubes of different diameter

    International Nuclear Information System (INIS)

    Tonkikh, Alexander A.; Obraztsova, Elena D.; Pozharov, Anatolii S.; Obraztsova, Ekaterina A.; Belkin, Alexey V.

    2012-01-01

    Single-wall carbon nanotubes with polyiodide chains inside are interesting from two points of view. According to predictions, first, the iodine structure type inside the nanotube is determined by the nanotube geometry. Second, after iodination all nanotubes become metallic. In this work, we made an attempt to check both predictions. To study the diameter-dependent properties we have taken for a gas-phase iodination the pristine single-wall carbon nanotubes grown by three different techniques providing a different average diameter: a chemical vapor deposition with a Co/Mo catalyst (CoMoCat) with a diameter range (0.6-1.3) nm, a high-pressure CO decomposition (HiPCO) - a diameter range (0.8-1.5) nm, and an aerosol technique with Fe catalyst - a diameter range (1.3-2.0) nm. The Raman spectra have shown a complication of the polyiodide chain structure while the nanotube diameter increased. The optical spectroscopy data (a suppression of E 11 band in the UV-Vis-NIR absorption spectrum) have confirmed the theoretical prediction about transformation of all nanotubes into metallic phase after doping. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Phthalimide containing donor-acceptor polymers for effective dispersion of single-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Baris Yilmaz

    2015-08-01

    Full Text Available Single-walled carbon nanotubes have been dispersed by novel phthalimide containing donor-acceptor type copolymers in organic media. Brominated phthalimide comonomer has been copolymerized with several electron rich structures using Suzuki and Stille coupling reactions. Carbon nanotube dispersion capability of the resultant polymers has been assessed by exploiting the non-covalent interaction of nanotube surface with the pi-system of conjugated backbone of polymers. Four polymers have been found to be good candidates for individually dispersing nanotubes in solution. In order to identify the dispersed nanotube species, 2D excitation-emission map and Raman spectroscopy have been performed. Molecular dynamics modelling has been utilized to reveal the binding energies of dispersants with the nanotube surface and the simulation results have been compared with the experimental findings. Both experimental and theoretical results imply the presence of a complex mechanism that governs the extent of dispersion capacity and selectivity of each conjugated polymeric dispersant in solubilizing carbon nanotubes.

  18. Comparative Performance of Acoustic-tagged and PIT-tagged Juvenile Salmonids

    Energy Technology Data Exchange (ETDEWEB)

    Hockersmith, Eric E.; Brown, Richard S.; Liedtke, Theresa L.

    2008-02-01

    Numerous research tools and technologies are currently being used to evaluate fish passage and survival to determine the impacts of the Federal Columbia River Power System (FCRPS) on endangered and threatened juvenile salmonids, including PIT tags, balloon tags, hydroacoustic evaluations, radio telemetry, and acoustic telemetry. Each has advantages and disadvantages, but options are restricted in some situations because of limited capabilities of a specific technology, lack of detection capability downstream, or availability of adequate numbers of fish. However, there remains concern about the comparative effects of the tag or the tagging procedure on fish performance. The recently developed Juvenile Salmonid Acoustic Telemetry System (JSATS) acoustic transmitter is the smallest active acoustic tag currently available. The goal of this study was to determine whether fish tagged with the JSATS acoustic-telemetry tag can provide unbiased estimates of passage behavior and survival within the performance life of the tag. We conducted both field and laboratory studies to assess tag effects. For the field evaluation we released a total of 996 acoustic-tagged fish in conjunction with 21,026 PIT-tagged fish into the tailrace of Lower Granite Dam on 6 and 13 May. Travel times between release and downstream dams were not significantly different for the majority of the reaches between acoustic-tagged and PIT-tagged fish. In addition to the field evaluation, a series of laboratory experiments were conducted to determine if growth and survival of juvenile Chinook salmon surgically implanted with acoustic transmitters is different than untagged or PIT tagged juvenile Chinook salmon. Only yearling fish with integrated and non-integrated transmitters experienced mortalities, and these were low (<4.5%). Mortality among sub-yearling control and PIT-tag treatments ranged up to 7.7% while integrated and non-integrated treatments had slightly higher rates (up to 8.3% and 7

  19. Side-by-side comparison of Raman spectra of anchored and suspended carbon nanomaterials

    International Nuclear Information System (INIS)

    Sidorov, Anton N; Pabba, Santosh; Cohn, Robert W; Sumanasekera, G U; Hewaparakrama, Kapila P

    2008-01-01

    Raman spectra of ordered carbon nanomaterials are quite sensitive to surface perturbations, including trace residues, structural defects and residual stress. This is demonstrated by a series of experiments with carbon nanotubes and graphene. Their spectra change due to subtle changes in preparation and attachment to the substrate and to each other. Differences are most clearly seen by forming a material into an air bridge and probing it in the air gap and at the anchor points. A monolayer graphene sheet, shows a larger disorder band at the anchor points than in the air gap. However, a bundle or rope of parallel-aligned single-wall nanotubes shows a larger disorder band in the gap than at the anchor points. For the graphene sheet the substrate surface deforms the graphene, leading to increases in the disorder band. For the rope, the close proximity of the nanotubes to each other appears to produce a larger stress than the rope resting on the substrate

  20. In Situ Raman Spectroscopy of COOH-Functionalized SWCNTs Trapped with Optoelectronic Tweezers

    Directory of Open Access Journals (Sweden)

    Peter J. Pauzauskie

    2012-01-01

    Full Text Available Optoelectronic tweezers (OETs were used to trap and deposit aqueous dispersions of carboxylic-acid-functionalized single-walled carbon nanotube bundles. Dark-field video microscopy was used to visualize the dynamics of the bundles both with and without virtual electrodes, showing rapid accumulation of carbon nanotubes when optical virtual electrodes are actuated. Raman microscopy was used to probe SWCNT materials following deposition onto metallic fiducial markers as well as during trapping. The local carbon nanotube concentration was observed to increase rapidly during trapping by more than an order of magnitude in less than one second due to localized optical dielectrophoresis forces. This combination of enrichment and spectroscopy with a single laser spot suggests a broad range of applications in physical, chemical, and biological sciences.

  1. Raman study of ? crystals

    Science.gov (United States)

    Pimenta, M. A.; Oliveira, M. A. S.; Bourson, P.; Crettez, J. M.

    1997-09-01

    In this work we present a polarized Raman study of 0953-8984/9/37/020/img7 single crystals for several values of the concentration 0953-8984/9/37/020/img8 made using different scattering geometries. The Raman spectra, composed of broad bands, have been fitted in accordance with a symmetry analysis which allowed us to assign the vibrational modes, and determine their frequencies and damping constants. The results are compatible with an average hexagonal symmetry for the solid solutions with x in the range 0953-8984/9/37/020/img9. In each of the spectra we found two bands at about 590 and 0953-8984/9/37/020/img10, probably associated with the existence of 0953-8984/9/37/020/img11 structures in the solid solutions.

  2. Surface enhanced Raman scattering

    CERN Document Server

    Furtak, Thomas

    1982-01-01

    In the course of the development of surface science, advances have been identified with the introduction of new diagnostic probes for analytical characterization of the adsorbates and microscopic structure of surfaces and interfaces. Among the most recently de­ veloped techniques, and one around which a storm of controversy has developed, is what has now been earmarked as surface enhanced Raman scattering (SERS). Within this phenomenon, molecules adsorbed onto metal surfaces under certain conditions exhibit an anomalously large interaction cross section for the Raman effect. This makes it possible to observe the detailed vibrational signature of the adsorbate in the ambient phase with an energy resolution much higher than that which is presently available in electron energy loss spectroscopy and when the surface is in contact with a much larger amount of material than that which can be tolerated in infrared absorption experiments. The ability to perform vibrational spectroscopy under these conditions would l...

  3. Raman Plus X: Biomedical Applications of Multimodal Raman Spectroscopy.

    Science.gov (United States)

    Das, Nandan K; Dai, Yichuan; Liu, Peng; Hu, Chuanzhen; Tong, Lieshu; Chen, Xiaoya; Smith, Zachary J

    2017-07-07

    Raman spectroscopy is a label-free method of obtaining detailed chemical information about samples. Its compatibility with living tissue makes it an attractive choice for biomedical analysis, yet its translation from a research tool to a clinical tool has been slow, hampered by fundamental Raman scattering issues such as long integration times and limited penetration depth. In this review we detail the how combining Raman spectroscopy with other techniques yields multimodal instruments that can help to surmount the translational barriers faced by Raman alone. We review Raman combined with several optical and non-optical methods, including fluorescence, elastic scattering, OCT, phase imaging, and mass spectrometry. In each section we highlight the power of each combination along with a brief history and presentation of representative results. Finally, we conclude with a perspective detailing both benefits and challenges for multimodal Raman measurements, and give thoughts on future directions in the field.

  4. Comparing the hierarchy of author given tags and repository given tags in a large document archive

    Science.gov (United States)

    Tibély, Gergely; Pollner, Péter; Palla, Gergely

    2016-10-01

    Folksonomies - large databases arising from collaborative tagging of items by independent users - are becoming an increasingly important way of categorizing information. In these systems users can tag items with free words, resulting in a tripartite item-tag-user network. Although there are no prescribed relations between tags, the way users think about the different categories presumably has some built in hierarchy, in which more special concepts are descendants of some more general categories. Several applications would benefit from the knowledge of this hierarchy. Here we apply a recent method to check the differences and similarities of hierarchies resulting from tags given by independent individuals and from tags given by a centrally managed repository system. The results from our method showed substantial differences between the lower part of the hierarchies, and in contrast, a relatively high similarity at the top of the hierarchies.

  5. User Interface Program for secure electronic tags

    International Nuclear Information System (INIS)

    Cai, Y.; Koehl, E.R.; Carlson, R.D.; Raptis, A.C.

    1995-05-01

    This report summarizes and documents the efforts of Argonne National Laboratory (ANL) in developing a secure tag communication user interface program comprising a tag monitor and a communication tool. This program can perform the same functions as the software that was developed at the Lawrence Livermore National Laboratory (LLNL), but it is enhanced with a user-friendly screen. It represents the first step in updating the TRANSCOM Tracking System (TRANSCOM) by incorporating a tag communication screen menu into the main menu of the TRANSCOM user program. A working version of TRANSCOM, enhanced with ANL secure-tag graphics, will strongly support the Department of Energy Warhead Dismantlement/Special Nuclear Materials Control initiatives. It will allow commercial satellite tracking of the movements and operational activities of treaty-limited items and transportation vehicles throughout Europe and the former USSR, as well as the continental US

  6. Flavour Tagging with the LHCb experiment

    CERN Multimedia

    Birnkraut, Alex

    2015-01-01

    Measurements of flavour oscillations and time-dependent CP asymmetries in neutral B meson systems require knowledge of the b quark production flavour. This identification is performed by the Flavour Tagging.

  7. Magnetic vector field tag and seal

    Science.gov (United States)

    Johnston, Roger G.; Garcia, Anthony R.

    2004-08-31

    One or more magnets are placed in a container (preferably on objects inside the container) and the magnetic field strength and vector direction are measured with a magnetometer from at least one location near the container to provide the container with a magnetic vector field tag and seal. The location(s) of the magnetometer relative to the container are also noted. If the position of any magnet inside the container changes, then the measured vector fields at the these locations also change, indicating that the tag has been removed, the seal has broken, and therefore that the container and objects inside may have been tampered with. A hollow wheel with magnets inside may also provide a similar magnetic vector field tag and seal. As the wheel turns, the magnets tumble randomly inside, removing the tag and breaking the seal.

  8. Expressed sequence tags (ESTs) and single nucleotide ...

    African Journals Online (AJOL)

    SERVER

    2008-02-19

    Feb 19, 2008 ... the discovery of the DNA, a new area of modern plant biotechnology begun. In plant ... Marker Assisted Breeding and Sequence Tagged Sites. (STS) are all in use in modern ...... and behaviour in the honey bee. Genome Res.

  9. 50 CFR 635.33 - Archival tags.

    Science.gov (United States)

    2010-10-01

    ... landing; furnish all requested information regarding the location and method of capture; and, as... recovery of the tag by a NMFS scientist, enforcement agent, or other person designated in writing by NMFS...

  10. Folksonomia: a linguagem das tags

    Directory of Open Access Journals (Sweden)

    Juliana de Assis

    2013-04-01

    Full Text Available http://dx.doi.org/10.5007/1518-2924.2013v18n36p85   A radicalização do potencial colaborativo da web atual aponta uma tendência de personalização da recuperação da informação através de ferramentas que exploram a linguagem natural na representação e no compartilhamento de conteúdos ao longo das redes sociais. Tal configuração sócio-técnica traz desafios aos profissionais da informação tanto para a descrição e compreensão dos fenômenos informacionais que ocorrem neste âmbito, quanto para a elaboração de produtos e serviços voltados para um usuário que se apresenta cada vez mais como sujeito informacional ao assumir um papel ativo diante da complexidade que caracteriza a organização da informação em contextos digitais. Este artigo apresenta conclusões de pesquisa, relacionadas às analises da linguagem utilizada em três ambientes colaborativos que utilizam a folksonomia (Social Tagging Systems. A partir de uma perspectiva fundamentada na Semiótica e na Análise de Redes Sociais, são identificadas e descritas as principais manifestações da linguagem gerada e compartilhada pelas redes sociais através destes ambientes.

  11. Chiral angle dependence of resonance window widths in (2n+m) families of single-walled carbon nanotubes

    Czech Academy of Sciences Publication Activity Database

    Hsieh, Y. P.; Hofmann, M.; Farhat, H.; Barros, E. B.; Kalbáč, Martin; Kong, J.; Liang, C. T.; Chen, Y. F.; Dresselhaus, M. S.

    2010-01-01

    Roč. 96, č. 10 (2010), s. 103118 ISSN 0003-6951 R&D Projects: GA MŠk ME09060 Institutional research plan: CEZ:AV0Z40400503 Keywords : carbon nanotubes * Raman spectra * SWNT Subject RIV: CG - Electrochemistry Impact factor: 3.820, year: 2010

  12. b-flavour tagging in pp collisions

    CERN Multimedia

    Birnkraut, Alex

    2015-01-01

    An essential ingredient of all time-dependent CP violation studies of B mesons is the ability to tag the initial flavour of the B meson. The harsh environment of 7 and 8 TeV pp collisions makes this a particularly difficult enterprise. We report progresses in the flavour tagging of B0 and Bs mesons, including developments of novel techniques like the use of an opposite side charm tagger.

  13. Role of intertube interactions in double- and triple-walled carbon nanotubes.

    Science.gov (United States)

    Hirschmann, Thomas Ch; Araujo, Paulo T; Muramatsu, Hiroyuki; Rodriguez-Nieva, Joaquin F; Seifert, Max; Nielsch, Kornelius; Kim, Yoong Ahm; Dresselhaus, Mildred S

    2014-02-25

    Resonant Raman spectroscopy studies are performed to access information about the intertube interactions and wall-to-wall distances in double- and triple-walled carbon nanotubes. Here, we explain how the surroundings of the nanotubes in a multiwalled system influence their radial breathing modes. Of particular interest, the innermost tubes in double- and triple-walled carbon nanotube systems are shown to be significantly shielded from environmental interactions, except for those coming from the intertube interaction with their own respective host tubes. From a comparison of the Raman results for bundled as well as individual fullerene-peapod-derived double- and triple-walled carbon nanotubes, we observe that metallic innermost tubes, when compared to their semiconducting counterparts, clearly show weaker intertube interactions. Additionally, we discuss a correlation between the wall-to-wall distances and the frequency upshifts of the radial breathing modes observed for the innermost tubes in individual double- and triple-walled carbon nanotubes. All results allow us to contemplate fundamental properties related to DWNTs and TWNTs, as for example diameter- and chirality-dependent intertube interactions. We also discuss differences in fullerene-peapod-derived and chemical vapor deposition grown double- and triple-walled systems with the focus on mechanical coupling and interference effects.

  14. Vector boson tagged jets and jet substructure

    Directory of Open Access Journals (Sweden)

    Vitev Ivan

    2018-01-01

    Full Text Available In these proceedings, we report on recent results related to vector boson-tagged jet production in heavy ion collisions and the related modification of jet substructure, such as jet shapes and jet momentum sharing distributions. Z0-tagging and γ-tagging of jets provides new opportunities to study parton shower formation and propagation in the quark-gluon plasma and has been argued to provide tight constrains on the energy loss of reconstructed jets. We present theoretical predictions for isolated photon-tagged and electroweak boson-tagged jet production in Pb+Pb collisions at √sNN = 5.02 TeV at the LHC, addressing the modification of their transverse momentum and transverse momentum imbalance distributions. Comparison to recent ATLAS and CMS experimental measurements is performed that can shed light on the medium-induced radiative corrections and energy dissipation due to collisional processes of predominantly quark-initiated jets. The modification of parton splitting functions in the QGP further implies that the substructure of jets in heavy ion collisions may differ significantly from the corresponding substructure in proton-proton collisions. Two such observables and the implication of tagging on their evaluation is also discussed.

  15. Clone tag detection in distributed RFID systems

    Science.gov (United States)

    Kamaludin, Hazalila; Mahdin, Hairulnizam

    2018-01-01

    Although Radio Frequency Identification (RFID) is poised to displace barcodes, security vulnerabilities pose serious challenges for global adoption of the RFID technology. Specifically, RFID tags are prone to basic cloning and counterfeiting security attacks. A successful cloning of the RFID tags in many commercial applications can lead to many serious problems such as financial losses, brand damage, safety and health of the public. With many industries such as pharmaceutical and businesses deploying RFID technology with a variety of products, it is important to tackle RFID tag cloning problem and improve the resistance of the RFID systems. To this end, we propose an approach for detecting cloned RFID tags in RFID systems with high detection accuracy and minimal overhead thus overcoming practical challenges in existing approaches. The proposed approach is based on consistency of dual hash collisions and modified count-min sketch vector. We evaluated the proposed approach through extensive experiments and compared it with existing baseline approaches in terms of execution time and detection accuracy under varying RFID tag cloning ratio. The results of the experiments show that the proposed approach outperforms the baseline approaches in cloned RFID tag detection accuracy. PMID:29565982

  16. Clone tag detection in distributed RFID systems.

    Science.gov (United States)

    Kamaludin, Hazalila; Mahdin, Hairulnizam; Abawajy, Jemal H

    2018-01-01

    Although Radio Frequency Identification (RFID) is poised to displace barcodes, security vulnerabilities pose serious challenges for global adoption of the RFID technology. Specifically, RFID tags are prone to basic cloning and counterfeiting security attacks. A successful cloning of the RFID tags in many commercial applications can lead to many serious problems such as financial losses, brand damage, safety and health of the public. With many industries such as pharmaceutical and businesses deploying RFID technology with a variety of products, it is important to tackle RFID tag cloning problem and improve the resistance of the RFID systems. To this end, we propose an approach for detecting cloned RFID tags in RFID systems with high detection accuracy and minimal overhead thus overcoming practical challenges in existing approaches. The proposed approach is based on consistency of dual hash collisions and modified count-min sketch vector. We evaluated the proposed approach through extensive experiments and compared it with existing baseline approaches in terms of execution time and detection accuracy under varying RFID tag cloning ratio. The results of the experiments show that the proposed approach outperforms the baseline approaches in cloned RFID tag detection accuracy.

  17. A hypergraph model of social tagging networks

    International Nuclear Information System (INIS)

    Zhang, Zi-Ke; Liu, Chuang

    2010-01-01

    The past few years have witnessed the great success of a new family of paradigms, so-called folksonomy, which allows users to freely associate tags with resources and efficiently manage them. In order to uncover the underlying structures and user behaviors in folksonomy, in this paper, we propose an evolutionary hypergraph model for explaining the emerging statistical properties. The present model introduces a novel mechanism that can not only assign tags to resources, but also retrieve resources via collaborative tags. We then compare the model with a real-world data set: Del.icio.us. Indeed, the present model shows considerable agreement with the empirical data in the following aspects: power-law hyperdegree distributions, negative correlation between clustering coefficients and hyperdegrees, and small average distances. Furthermore, the model indicates that most tagging behaviors are motivated by labeling tags on resources, and the tag plays a significant role in effectively retrieving interesting resources and making acquaintances with congenial friends. The proposed model may shed some light on the in-depth understanding of the structure and function of folksonomy

  18. Smart-tag Based Data Dissemination

    DEFF Research Database (Denmark)

    Bonnet, Philippe; Beaufour, Allan; Leopold, Martin

    2002-01-01

    Monitoring wide, hostile areas requires disseminating data between fixed, disconnected clusters of sensor nodes. It is not always possible to install long-range radios in order to cover the whole area. We propose to leverage the movement of mobile individuals, equipped with smart-tags, to dissemi......-tag based data dissemination. We use simulation to study the characteristics of the model we propose. Finally, we present an implementation based on Bluetooth smart-tags.......Monitoring wide, hostile areas requires disseminating data between fixed, disconnected clusters of sensor nodes. It is not always possible to install long-range radios in order to cover the whole area. We propose to leverage the movement of mobile individuals, equipped with smart......-tags, to disseminate data across disconnected static nodes spread across a wide area. Static nodes and mobile smart-tags exchange data when they are in the vicinity of each other; smart-tags disseminate data as they move around. In this paper, we propose an algorithm for update propagation and a model for smart...

  19. Multi-Threaded DNA Tag/Anti-Tag Library Generator for Multi-Core Platforms

    Science.gov (United States)

    2009-05-01

    base pair)  Watson ‐ Crick  strand pairs that bind perfectly within pairs, but poorly across pairs. A variety  of  DNA  strand hybridization metrics...AFRL-RI-RS-TR-2009-131 Final Technical Report May 2009 MULTI-THREADED DNA TAG/ANTI-TAG LIBRARY GENERATOR FOR MULTI-CORE PLATFORMS...TYPE Final 3. DATES COVERED (From - To) Jun 08 – Feb 09 4. TITLE AND SUBTITLE MULTI-THREADED DNA TAG/ANTI-TAG LIBRARY GENERATOR FOR MULTI-CORE

  20. Improving Recommendations in Tag-based Systems with Spectral Clustering of Tag Neighbors

    DEFF Research Database (Denmark)

    Pan, Rong; Xu, Guandong; Dolog, Peter

    2012-01-01

    Tag as a useful metadata reflects the collaborative and conceptual features of documents in social collaborative annotation systems. In this paper, we propose a collaborative approach for expanding tag neighbors and investigate the spectral clustering algorithm to filter out noisy tag neighbors...... in order to get appropriate recommendation for users. The preliminary experiments have been conducted on MovieLens dataset to compare our proposed approach with the traditional collaborative filtering recommendation approach and naive tag neighbors expansion approach in terms of precision, and the result...... demonstrates that our approach could considerably improve the performance of recommendations....

  1. Transparent conducting oxide nanotubes

    Science.gov (United States)

    Alivov, Yahya; Singh, Vivek; Ding, Yuchen; Nagpal, Prashant

    2014-09-01

    Thin film or porous membranes made of hollow, transparent, conducting oxide (TCO) nanotubes, with high chemical stability, functionalized surfaces and large surface areas, can provide an excellent platform for a wide variety of nanostructured photovoltaic, photodetector, photoelectrochemical and photocatalytic devices. While large-bandgap oxide semiconductors offer transparency for incident light (below their nominal bandgap), their low carrier concentration and poor conductivity makes them unsuitable for charge conduction. Moreover, materials with high conductivity have nominally low bandgaps and hence poor light transmittance. Here, we demonstrate thin films and membranes made from TiO2 nanotubes heavily-doped with shallow Niobium (Nb) donors (up to 10%, without phase segregation), using a modified electrochemical anodization process, to fabricate transparent conducting hollow nanotubes. Temperature dependent current-voltage characteristics revealed that TiO2 TCO nanotubes, doped with 10% Nb, show metal-like behavior with resistivity decreasing from 6.5 × 10-4 Ωcm at T = 300 K (compared to 6.5 × 10-1 Ωcm for nominally undoped nanotubes) to 2.2 × 10-4 Ωcm at T = 20 K. Optical properties, studied by reflectance measurements, showed light transmittance up to 90%, within wavelength range 400 nm-1000 nm. Nb doping also improves the field emission properties of TCO nanotubes demonstrating an order of magnitude increase in field-emitter current, compared to undoped samples.

  2. Carbon nanotube filters

    Science.gov (United States)

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

    2004-09-01

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

  3. Comparative studies of electrochemical properties of carbon nanotubes and nanostructured boron carbide

    Science.gov (United States)

    Singh, Paviter; Kaur, Gurpreet; Singh, Kulwinder; Singh, Bikramjeet; Kaur, Manjot; Kumar, Manjeet; Bala, Rajni; Kumar, Akshay

    2018-05-01

    Boron carbide (B4C) and carbon nanotubes (CNTs) have the potential to act as electrocatalyst as these material show bifunctional behavior. B4C and CNTs were synthesized using solvothermal method. B4C display great catalytic activity as compared to CNTs. Raman spectra confirmed the formation of nanostructured carbon nanotubes. The observed onset potential was smaller 1.58 V in case of B4C as compared to CNTs i.e. 1.96 V in cyclic voltammetry. B4C material can emerge as a promising bifunctional electrocatalyst for battery applications.

  4. Growth of single walled carbon nanotubes networks using Al - Ni as catalyst

    International Nuclear Information System (INIS)

    Kotlar, M.; Vesely, M.; Redhammer, R.; Vretenar, V.

    2011-01-01

    The growth of SWCNTs networks on the SiO 2 chips was examined for different growth temperatures and annealing times. According to Raman spectroscopy the temperature is a significant parameter which affects quality of carbon nanotubes. For higher temperatures (850 - 900 deg C) the best quality was achieved. On the other hand, the different annealing times did not affect results of our experiments. SWCNTs network consists of large amount of intersecting carbon nanotubes. This network is electrically conductive over large distances. The SWCNTs networks can be used as transparent conductive layer or as sensitive layer of chemical sensors. (authors)

  5. Design of titania nanotube structures by focused laser beam direct writing

    International Nuclear Information System (INIS)

    Enachi, Mihai; Stevens-Kalceff, Marion A.; Sarua, Andrei; Ursaki, Veaceslav; Tiginyanu, Ion

    2013-01-01

    In this work, we report on electrochemical fabrication of titania films consisting of nanotubes (NTs) and their treatment by focused laser beam. The results of sample characterization by optical and scanning electron microscopy, cathodoluminescence imaging, and Raman scattering scanning spectroscopy are compared to those inherent to specimens subjected to thermal treatment in a furnace. The obtained data demonstrate possibilities for controlling crystallographic structure of TiO 2 NTs by focused laser beam direct writing. These findings open new prospects for the design and fabrication of spatial architectures based on titania nanotubes

  6. Plasma treatment of multiwall carbon nanotubes for dispersion improvement in water

    International Nuclear Information System (INIS)

    Chen Changlun; Ogino, Akihisa; Nagatsu, Masaaki; Wang Xiangke

    2010-01-01

    Microwave excited Ar/H 2 O surface-wave plasma was used to treat multiwall carbon nanotubes (MWCNTs) to modify their surface characteristics and thus improve their dispersion capability in water. Changes in the atom composition and structure properties of MWCNTs were analyzed using x-ray photoelectron spectroscopy and Raman spectroscopy, and the surface morphology of MWCNTs was observed by field emission scanning electron microscopy and scanning transmission electron microscopy. The results indicated that Ar/H 2 O plasma treatment greatly enhanced the content of oxygen, and modified surface microstructure properties. The integrity of nanotube patterns, however, was not damaged.

  7. Resonant Impulsive Stimulated Raman Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtari, A; Chesnoy, J

    1988-03-15

    Using a femtosecond dye laser, we observe in real-time vibrational oscillations excited by impulsive stimulated Raman scattering (ISRS) close to an electronic resonance. We perform single-beam Raman excitation and probe the driven coherence by a polarization-sensitive detection. We demonstrate for the first time impulsively Raman-induced dichroism, birefringence as well as frequency and time delay shifts. We analyse the characteristics of resonant ISRS on a vibrational mode of a dye molecule (malachite green) in solution.

  8. Resonant Impulsive Stimulated Raman Scattering

    International Nuclear Information System (INIS)

    Mokhtari, A.; Chesnoy, J.

    1988-01-01

    Using a femtosecond dye laser, we observe in real-time vibrational oscillations excited by impulsive stimulated Raman scattering (ISRS) close to an electronic resonance. We perform single-beam Raman excitation and probe the driven coherence by a polarization-sensitive detection. We demonstrate for the first time impulsively Raman-induced dichroism, birefringence as well as frequency and time delay shifts. We analyse the characteristics of resonant ISRS on a vibrational mode of a dye molecule (malachite green) in solution

  9. EB treatment of carbon nanotube-reinforced polymer composites

    International Nuclear Information System (INIS)

    Szebényi, G.; Romhány, G.; Vajna, B.; Czvikovszky, T.

    2012-01-01

    A small amount — less than 0.5% — carbon nanotube reinforcement may improve the mechanical properties of epoxy based composite materials significantly. The basic technical problem on one side is the dispersion of the nanotubes into the viscous matrix resin, namely, the fine powder-like — less than 100 nanometer diameter — nanotubes are prone to form aggregates. On the other side, the good connection between the nanofiber and matrix, which is determining the success of the reinforcement, requires some efficient adhesion promoting treatment. The goal of our research was to give one such treatment capable of industrial size application. A two step curing epoxy/vinylester resin process technology has been developed where the epoxy component has been cured conventionally, while the vinylester has been cured by electron treatment afterwards. The sufficient irradiation dose has been selected according to Raman spectroscopy characterization. Using the developed hybrid resin system hybrid composites containing carbon fibers and multiwalled carbon nanotubes have been prepared. The effect of the electron beam induced curing of the vinylester resin on the mechanical properties of the composites has been characterized by three point bending and interlaminar shear tests, which showed clearly the superiority of the developed resin system. The results of the mechanical tests have been supported by AFM studies of the samples, which showed that the difference in the viscoelastic properties of the matrix constituents decreased significantly by the electron beam treatment.

  10. Human-Centered Implicit Tagging: Overview and Perspectives

    NARCIS (Netherlands)

    Soleymani, Mohammad; Pantic, Maja

    2012-01-01

    Tags are an effective form of metadata which help users to locate and browse multimedia content of interest. Tags can be generated by users (user-generated explicit tags), automatically from the content (content-based tags), or assigned automatically based on non-verbal behavioral reactions of users

  11. Overview of the recombinant proteins purification by affinity tags and ...

    African Journals Online (AJOL)

    From protein within isolation process which the same matter increases labor costs further and prevents application of these tags in industrial scale. Therefore proper replacement is emphasized for enzymatic removal of purification tags. Keywords: protein purification; recombinant proteins; self-cleavable tags; Intein tags; ...

  12. Annotating images by harnessing worldwide user-tagged photos

    NARCIS (Netherlands)

    Li, X.; Snoek, C.G.M.; Worring, M.

    2009-01-01

    Automatic image tagging is important yet challenging due to the semantic gap and the lack of learning examples to model a tag's visual diversity. Meanwhile, social user tagging is creating rich multimedia content on the Web. In this paper, we propose to combine the two tagging approaches in a

  13. Ammonium Laurate Surfactant for Cleaner Deposition of Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Hanna M. [Department of Material Science and Engineering and ‡Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States; Meany, Brendan [Department of Material Science and Engineering and ‡Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States; Ticey, Jeremy [Department of Material Science and Engineering and ‡Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States; Sun, Chuan-Fu [Department of Material Science and Engineering and ‡Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States; Wang, YuHuang [Department of Material Science and Engineering and ‡Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States; Cumings, John [Department of Material Science and Engineering and ‡Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States

    2015-06-15

    Experiments probing the properties of individual carbon nanotubes (CNTs) and those measuring bulk composites show vastly different results. One major issue limiting the results is that the procedures required to separate and test CNTs introduce contamination that changes the properties of the CNT. These contamination residues often come from the resist used in lithographic processing and the surfactant used to suspend and deposit the CNTs, commonly sodium dodecyl sulfate (SDS). Here we present ammonium laurate (AL), a surfactant that has previously not been used for this application, which differs from SDS only by substitution of ionic constituents but shows vastly cleaner depositions. In addition, we show that compared to SDS, AL-suspended CNTs have greater shelf stability and more selective dispersion. These results are verified using transmission electron microscopy, atomic force microscopy, ζ-potential measurements, and Raman and absorption optical spectroscopy. This surfactant is simple to prepare, and the nanotube solutions require minimal sonication and centrifugation in order to outperform SDS.

  14. Defect engineering of the electrochemical characteristics of carbon nanotube varieties

    International Nuclear Information System (INIS)

    Hoefer, Mark A.; Bandaru, Prabhakar R.

    2010-01-01

    The electrochemical behavior of carbon nanotubes (CNTs) containing both intrinsic and extrinsically introduced defects has been investigated through the study of bamboo and hollow multiwalled CNT morphologies. The controlled addition of argon ions was used for varying the charge and type of extrinsic defects. It was indicated from Raman spectroscopy and voltammetry that the electrocatalytic response of hollow type CNTs could be tailored more significantly, compared to bamboo type CNTs which have innately high reactive site densities and are less amenable to modification. An in-plane correlation length parameter was used to understand the variation of the defect density as a function of argon ion irradiation. The work has implications in the design of nanotube based chemical sensors, facilitated through the introduction of suitable reactive sites.

  15. Defect engineering of the electrochemical characteristics of carbon nanotube varieties

    Science.gov (United States)

    Hoefer, Mark A.; Bandaru, Prabhakar R.

    2010-08-01

    The electrochemical behavior of carbon nanotubes (CNTs) containing both intrinsic and extrinsically introduced defects has been investigated through the study of bamboo and hollow multiwalled CNT morphologies. The controlled addition of argon ions was used for varying the charge and type of extrinsic defects. It was indicated from Raman spectroscopy and voltammetry that the electrocatalytic response of hollow type CNTs could be tailored more significantly, compared to bamboo type CNTs which have innately high reactive site densities and are less amenable to modification. An in-plane correlation length parameter was used to understand the variation of the defect density as a function of argon ion irradiation. The work has implications in the design of nanotube based chemical sensors, facilitated through the introduction of suitable reactive sites.

  16. Diameter sensitive effect in singlewalled carbon nanotubes upon acid treatment

    International Nuclear Information System (INIS)

    Costa, S.; Borowiak-Palen, E.

    2009-01-01

    Singlewalled carbon nanotubes (SWCNT) exhibit very unique properties. As an electronic system they undergo amphoteric doping effects (n-type and p-type) which can be reversed. These processes affect the optical and vibronic properties of the carbon nanotubes. The most common and widely used procedure which changes the properties of the SWCNT is acid treatment applied as a purification procedure. This effect has been widely studied but not fully understood so far. Here, we present a study, in which a diameter sensitive effect has been observed. Therefore, two kinds of SWCNT samples have been studied: (i) produced via chemical vapour deposition with a broad diameter distribution, and (ii) synthesised by the laser ablation technique which is commonly known to result in narrow diameter distribution bulk SWCNT samples. Resonance Raman spectroscopy, optical absorption spectroscopy, and Fourier transform middle-infrared spectroscopy have been applied for the characterisation of the samples.

  17. Methodologies for Improved Tag Cloud Generation with Clustering

    DEFF Research Database (Denmark)

    Leginus, Martin; Dolog, Peter; Lage, Ricardo Gomes

    2012-01-01

    Tag clouds are useful means for navigation in the social web systems. Usually the systems implement the tag cloud generation based on tag popularity which is not always the best method. In this paper we propose methodologies on how to combine clustering into the tag cloud generation to improve...... coverage and overlap. We study several clustering algorithms to generate tag clouds. We show that by extending cloud generation based on tag popularity with clustering we slightly improve coverage. We also show that if the cloud is generated by clustering independently of the tag popularity baseline we...

  18. Associated Particle Tagging (APT) in Magnetic Spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, David V.; Baciak, James E.; Stave, Sean C.; Chichester, David; Dale, Daniel; Kim, Yujong; Harmon, Frank

    2012-10-16

    Summary In Brief The Associated Particle Tagging (APT) project, a collaboration of Pacific Northwest National Laboratory (PNNL), Idaho National Laboratory (INL) and the Idaho State University (ISU)/Idaho Accelerator Center (IAC), has completed an exploratory study to assess the role of magnetic spectrometers as the linchpin technology in next-generation tagged-neutron and tagged-photon active interrogation (AI). The computational study considered two principle concepts: (1) the application of a solenoidal alpha-particle spectrometer to a next-generation, large-emittance neutron generator for use in the associated particle imaging technique, and (2) the application of tagged photon beams to the detection of fissile material via active interrogation. In both cases, a magnetic spectrometer momentum-analyzes charged particles (in the neutron case, alpha particles accompanying neutron generation in the D-T reaction; in the tagged photon case, post-bremsstrahlung electrons) to define kinematic properties of the relevant neutral interrogation probe particle (i.e. neutron or photon). The main conclusions of the study can be briefly summarized as follows: Neutron generator: • For the solenoidal spectrometer concept, magnetic field strengths of order 1 Tesla or greater are required to keep the transverse size of the spectrometer smaller than 1 meter. The notional magnetic spectrometer design evaluated in this feasibility study uses a 5-T magnetic field and a borehole radius of 18 cm. • The design shows a potential for 4.5 Sr tagged neutron solid angle, a factor of 4.5 larger than achievable with current API neutron-generator designs. • The potential angular resolution for such a tagged neutron beam can be less than 0.5o for modest Si-detector position resolution (3 mm). Further improvement in angular resolution can be made by using Si-detectors with better position resolution. • The report documents several features of a notional generator design incorporating the

  19. A brief examination of optical tagging technologies.

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, Mark R.; Cahill, Paul A. (Aspecular Optics, Dayton, OH); Drummond, Timothy J.; Wilcoxon, Jess Patrick

    2003-07-01

    Presented within this report are the results of a brief examination of optical tagging technologies funded by the Laboratory Directed Research and Development (LDRD) program at Sandia National Laboratories. The work was performed during the summer months of 2002 with total funding of $65k. The intent of the project was to briefly examine a broad range of approaches to optical tagging concentrating on the wavelength range between ultraviolet (UV) and the short wavelength infrared (SWIR, {lambda} < 2{micro}m). Tagging approaches considered include such things as simple combinations of reflective and absorptive materials closely spaced in wavelength to give a high contrast over a short range of wavelengths, rare-earth oxides in transparent binders to produce a narrow absorption line hyperspectral tag, and fluorescing materials such as phosphors, dies and chemically precipitated particles. One technical approach examined in slightly greater detail was the use of fluorescing nano particles of metals and semiconductor materials. The idea was to embed such nano particles in an oily film or transparent paint binder. When pumped with a SWIR laser such as that produced by laser diodes at {lambda}=1.54{micro}m, the particles would fluoresce at slightly longer wavelengths, thereby giving a unique signal. While it is believed that optical tags are important for military, intelligence and even law enforcement applications, as a business area, tags do not appear to represent a high on return investment. Other government agencies frequently shop for existing or mature tag technologies but rarely are interested enough to pay for development of an untried technical approach. It was hoped that through a relatively small investment of laboratory R&D funds, enough technologies could be identified that a potential customers requirements could be met with a minimum of additional development work. Only time will tell if this proves to be correct.

  20. Carbon nanotube junctions and devices

    NARCIS (Netherlands)

    Postma, H.W.Ch.

    2001-01-01

    In this thesis Postma presents transport experiments performed on individual single-wall carbon nanotubes. Carbon nanotubes are molecules entirely made of carbon atoms. The electronic properties are determined by the exact symmetry of the nanotube lattice, resulting in either metallic or

  1. Peptide-tagged proteins in aqueous two-phase systems

    OpenAIRE

    Nilsson, Anna

    2002-01-01

    This thesis deals with proteins containing peptide tags for improved partitioning in aqueous two-phase systems. Qualitatively the peptide-tagged protein partitioning could be predicted from peptide data, i.e. partitioning trends found for peptides were also found for the peptide-tagged proteins. However, full effect of the tag as expected from peptide partitioning was not found in the tagged protein. When alkyl-ethylene oxide surfactant was included in a two-polymer system, almost full effect...

  2. Tag and Neighbor based Recommender systems for Medical events

    DEFF Research Database (Denmark)

    Bayyapu, Karunakar Reddy; Dolog, Peter

    2010-01-01

    This paper presents an extension of a multifactor recommendation approach based on user tagging with term neighbours. Neighbours of words in tag vectors and documents provide for hitting larger set of documents and not only those matching with direct tag vectors or content of the documents. Tag...... in the situations where the quality of tags is lower. We discuss the approach on the examples from the existing Medworm system to indicate the usefulness of the approach....

  3. Evaluation of visible implant elastomer tags in zebrafish (Danio rerio

    Directory of Open Access Journals (Sweden)

    Claudia Hohn

    2013-11-01

    The use of the visible implant elastomer (VIE tagging system in zebrafish (Danio rerio was examined. Two tag orientations (horizontal and vertical at the dorsal fin base were tested for tag retention, tag fragmentation and whether VIE tags affected growth and survival of juvenile zebrafish (1–4 month post hatch. Six tag locations (abdomen, anal fin base, caudal peduncle, dorsal fin base, pectoral fin base, isthmus and 5 tag colors (yellow, red, pink, orange, blue were evaluated for ease of VIE tag application and tag visibility in adult zebrafish. Long-term retention (1 year and multiple tagging sites (right and left of dorsal fin and pectoral fin base were examined in adult zebrafish. Lastly, survival of recombination activation gene 1−/− (rag1−/− zebrafish was evaluated after VIE tagging. The best tag location was the dorsal fin base, and the most visible tag color was pink. Growth rate of juvenile zebrafish was not affected by VIE tagging. Horizontal tagging is recommended in early stages of fish growth (1–2 months post hatch. VIE tags were retained for 1 year and tagging did not interfere with long-term growth and survival. There was no mortality associated with VIE tagging in rag1−/− zebrafish. The VIE tagging system is highly suitable for small-sized zebrafish. When familiar with the procedure, 120 adult zebrafish can be tagged in one hour. It does not increase mortality in adult zebrafish or interfere with growth in juvenile or adult zebrafish.

  4. Synthesis of carbon nanotubes and nanotube forests on copper catalyst

    International Nuclear Information System (INIS)

    Kruszka, Bartosz; Terzyk, Artur P; Wiśniewski, Marek; Gauden, Piotr A; Szybowicz, Mirosław

    2014-01-01

    The growth of carbon nanotubes on bulk copper is studied. We show for the first time, that super growth chemical vapor deposition method can be successfully applied for preparation of nanotubes on copper catalyst, and the presence of hydrogen is necessary. Next, different methods of copper surface activation are studied, to improve catalyst efficiency. Among them, applied for the first time for copper catalyst in nanotubes synthesis, sulfuric acid activation is the most promising. Among tested samples the surface modified for 10 min is the most active, causing the growth of vertically aligned carbon nanotube forests. Obtained results have potential importance in application of nanotubes and copper in electronic chips and nanodevices. (paper)

  5. EnTagRec : an enhanced tag recommendation system for software information sites

    NARCIS (Netherlands)

    Wang, S.; Lo, D.; Vasilescu, B.N.; Serebrenik, A.

    2014-01-01

    Software engineers share experiences with modern technologies by means of software information sites, such as STACK OVERFLOW. These sites allow developers to label posted content, referred to as software objects, with short descriptions, known as tags. However, tags assigned to objects tend to be

  6. Tag-to-Tag Interference Suppression Technique Based on Time Division for RFID

    Directory of Open Access Journals (Sweden)

    Grishma Khadka

    2017-01-01

    Full Text Available Radio-frequency identification (RFID is a tracking technology that enables immediate automatic object identification and rapid data sharing for a wide variety of modern applications using radio waves for data transmission from a tag to a reader. RFID is already well established in technical areas, and many companies have developed corresponding standards and measurement techniques. In the construction industry, effective monitoring of materials and equipment is an important task, and RFID helps to improve monitoring and controlling capabilities, in addition to enabling automation for construction projects. However, on construction sites, there are many tagged objects and multiple RFID tags that may interfere with each other’s communications. This reduces the reliability and efficiency of the RFID system. In this paper, we propose an anti-collision algorithm for communication between multiple tags and a reader. In order to suppress interference signals from multiple neighboring tags, the proposed algorithm employs the time-division (TD technique, where tags in the interrogation zone are assigned a specific time slot so that at every instance in time, a reader communicates with tags using the specific time slot. We present representative computer simulation examples to illustrate the performance of the proposed anti-collision technique for multiple RFID tags.

  7. Topical tags vs non-topical tags : Towards a bipartite classification?

    NARCIS (Netherlands)

    Basile, Valerio; Peroni, Silvio; Tamburini, Fabio; Vitali, Fabio

    2015-01-01

    In this paper we investigate whether it is possible to create a computational approach that allows us to distinguish topical tags (i.e. talking about the topic of a resource) and non-topical tags (i.e. describing aspects of a resource that are not related to its topic) in folksonomies, in a way that

  8. Extracting Usage Patterns and the Analysis of Tag Connection Dynamics within Collaborative Tagging Systems

    Directory of Open Access Journals (Sweden)

    Daniel MICAN

    2013-01-01

    Full Text Available Collaborative tagging has become a very popular way of annotation, thanks to the fact that any entity may be labeled by any individual based on his own reason. In this paper we present the results of the case study carried out on the basis of data gathered at different time intervals from the social tagging system developed and implemented on Întelepciune.ro. Analyzing collective data referring to the way in which community members associate different tags, we have observed that between tags, links are formed which become increasingly stable with the passing of time. Following the application of methodology specific to network analysis, we have managed to extract information referring to tag popularity, their influence within the network and the degree to which a tag depends upon another. As such, we have succeeded in determining different semantic structures within the collective tagging system and see their evolution at different stages in time. Furthermore, we have pictured the way in which tag rec-ommendations can be executed and that they can be integrated within recommendation sys-tems. Thus, we will be able to identify experts and trustworthy content based on different cat-egories of interest.

  9. Electrochemical Charging of Individual Single-Walled Carbon Nanotubes

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Farhat, H.; Kavan, Ladislav; Kong, J.; Sasaki, K.; Saito, R.; Dresselhaus, M. S.

    2009-01-01

    Roč. 3, č. 8 (2009), s. 2320-2328 ISSN 1936-0851 R&D Projects: GA ČR GC203/07/J067; GA AV ČR IAA400400804; GA AV ČR IAA400400911; GA AV ČR KAN200100801; GA MŠk ME09060 Institutional research plan: CEZ:AV0Z40400503 Keywords : single-walled carbon nanotubes * Raman spectroscopy * electrochemical gating * spectroelectrochemistry Subject RIV: CG - Electrochemistry Impact factor: 7.493, year: 2009

  10. pH sensor based on boron nitride nanotubes.

    Science.gov (United States)

    Huang, Q; Bando, Y; Zhao, L; Zhi, C Y; Golberg, D

    2009-10-14

    A submicrometer-sized pH sensor based on biotin-fluorescein-functionalized multiwalled BN nanotubes with anchored Ag nanoparticles is designed. Intrinsic pH-dependent photoluminescence and Raman signals in attached fluorescein molecules enhanced by Ag nanoparticles allow this novel nanohybrid to perform as a practical pH sensor. It is able to work in a submicrometer-sized space. For example, the sensor may determine the environmental pH of sub-units in living cells where a traditional optical fiber sensor fails because of spatial limitations.

  11. pH sensor based on boron nitride nanotubes

    International Nuclear Information System (INIS)

    Huang, Q; Bando, Y; Zhao, L; Zhi, C Y; Golberg, D

    2009-01-01

    A submicrometer-sized pH sensor based on biotin-fluorescein-functionalized multiwalled BN nanotubes with anchored Ag nanoparticles is designed. Intrinsic pH-dependent photoluminescence and Raman signals in attached fluorescein molecules enhanced by Ag nanoparticles allow this novel nanohybrid to perform as a practical pH sensor. It is able to work in a submicrometer-sized space. For example, the sensor may determine the environmental pH of sub-units in living cells where a traditional optical fiber sensor fails because of spatial limitations.

  12. Covalent functionalization of carbon nanotubes with tetramanganese complexes

    International Nuclear Information System (INIS)

    Meyer, Carola; Frielinghaus, Robert; Saelhoff, Anna-Katharina; Schneider, Claus M.; Besson, Claire; Floetotto, Henrik; Koegerler, Paul; Houben, Lothar

    2012-01-01

    We present first results on the covalent chemical functionalization of single-walled carbon nanotubes with polynuclear {Mn 4 } coordination complexes. Raman spectra prove that the reaction can only be achieved for tubes which have been oxidized to create carboxylic groups. HRTEM is used to show that the reaction can be carried out directly on a substrate as well. Analysis of the D/G intensity ratio for different oxidation times shows that it is possible to reduce the amount of defects created. This is important for the future application of this material in transport devices. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Adsorption of O2 on a (4, 2) carbon nanotube

    International Nuclear Information System (INIS)

    Liu, H J; Zhai, J P; Chan, C T; Tang, Z K

    2007-01-01

    The physisorption and chemisorption of O 2 on the outer wall of a (4, 2) carbon nanotube have been studied by density functional calculations. The minimum-energy paths from physisorbed products to chemisorbed products are calculated by the nudged elastic band technique. Our theoretical calculations and experimentally measured Raman spectra both indicate that the (4, 2) tube is less air stable than the (5, 0) tube, which could be used to select a single chirality from a mixture of these 4 A tubes

  14. Pressure effects on single wall carbon nanotube bundles

    International Nuclear Information System (INIS)

    Teredesai, P.V.; Sharma, S.M.; Karmakar, S.; Sikka, S.K.; Govindaraj, A.; Rao, C.N.R.

    2001-01-01

    We report high pressure Raman studies on single wall carbon nanotube bundles under hydrostatic conditions using two different pressure transmitting media, alcohol mixture and pure water. The radial and tangential modes show a blue shift when SWNT bundle is immersed in the liquids at ambient pressures. The pressure dependence of the radial modes is the same in both liquids. However, the pressure derivatives dω/dP of the tangential modes are slightly higher for the water medium. Raman results are compared with studies under non-hydrostatic conditions and with recent high-pressure X-ray studies. It is seen that the mode frequencies of the recovered sample after pressure cycling from 26 GPa are downshifted by ∝7-10 cm -1 as compared to the starting sample. (orig.)

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

    Directory of Open Access Journals (Sweden)

    Claudio Larosa

    2017-09-01

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

  16. Sequence tagging reveals unexpected modifications in toxicoproteomics

    Science.gov (United States)

    Dasari, Surendra; Chambers, Matthew C.; Codreanu, Simona G.; Liebler, Daniel C.; Collins, Ben C.; Pennington, Stephen R.; Gallagher, William M.; Tabb, David L.

    2010-01-01

    Toxicoproteomic samples are rich in posttranslational modifications (PTMs) of proteins. Identifying these modifications via standard database searching can incur significant performance penalties. Here we describe the latest developments in TagRecon, an algorithm that leverages inferred sequence tags to identify modified peptides in toxicoproteomic data sets. TagRecon identifies known modifications more effectively than the MyriMatch database search engine. TagRecon outperformed state of the art software in recognizing unanticipated modifications from LTQ, Orbitrap, and QTOF data sets. We developed user-friendly software for detecting persistent mass shifts from samples. We follow a three-step strategy for detecting unanticipated PTMs in samples. First, we identify the proteins present in the sample with a standard database search. Next, identified proteins are interrogated for unexpected PTMs with a sequence tag-based search. Finally, additional evidence is gathered for the detected mass shifts with a refinement search. Application of this technology on toxicoproteomic data sets revealed unintended cross-reactions between proteins and sample processing reagents. Twenty five proteins in rat liver showed signs of oxidative stress when exposed to potentially toxic drugs. These results demonstrate the value of mining toxicoproteomic data sets for modifications. PMID:21214251

  17. Electronic tagging and integrated product intelligence

    Science.gov (United States)

    Swerdlow, Martin; Weeks, Brian

    1996-03-01

    The advent of 'intelligent,' electronic data bearing tags is set to revolutionize the way industrial and retail products are identified and tracked throughout their life cycles. The dominant system for unique identification today is the bar code, which is based on printed symbology and regulated by the International Article Numbering Association. Bar codes provide users with significant operational advantages and generate considerable added value to packaging companies, product manufacturers, distributors and retailers, across supply chains in many different sectors, from retailing, to baggage handling and industrial components, e.g., for vehicles or aircraft. Electronic tags offer the potential to: (1) record and store more complex data about the product or any modifications which occur during its life cycle; (2) access (and up-date) stored data in real time in a way which does not involve contact with the product or article; (3) overcome the limitations imposed by systems which rely on line-of-sight access to stored data. Companies are now beginning to consider how electronic data tags can be used, not only to improve the efficiency of their supply chain processes, but also to revolutionize the way they do business. This paper reviews the applications and business opportunities for electronic tags and outlines CEST's strategy for achieving an 'open' standard which will ensure that tags from different vendors can co-exist on an international basis.

  18. Tagging: An Organization Scheme for the Internet

    Directory of Open Access Journals (Sweden)

    Marijke A. Visser

    2010-03-01

    Full Text Available How should the information on the Internet be organized? This question and the possible solutions spark debates among people concerned with how we identify, classify, and retrieve Internet content. This paper discusses the benefits and the controversies of using a tagging system to organize Internet resources. Tagging refers to a classification system where individual Internet users apply labels, or tags, to digital resources. Tagging increased in popularity with the advent of Web 2.0 applications that encourage interaction among users. As more information is available digitally, the challenge to find an organizational system scalable to the Internet will continue to require forward thinking. Trained to ensure access to a range of informational resources, librarians need to be concerned with access to Internet content. Librarians can play a pivotal role by advocating for a system that supports the user at the moment of need. Tagging may just be the necessary system.

  19. Electron diffraction from carbon nanotubes

    International Nuclear Information System (INIS)

    Qin, L-C

    2006-01-01

    The properties of a carbon nanotube are dependent on its atomic structure. The atomic structure of a carbon nanotube can be defined by specifying its chiral indices (u, v), that specify its perimeter vector (chiral vector), with which the diameter and helicity are also determined. The fine electron beam available in a modern transmission electron microscope (TEM) offers a unique probe to reveal the atomic structure of individual nanotubes. This review covers two aspects related to the use of the electron probe in the TEM for the study of carbon nanotubes: (a) to understand the electron diffraction phenomena for inter-pretation of the electron diffraction patterns of carbon nanotubes and (b) to obtain the chiral indices (u, v), of the carbon nanotubes from the electron diffraction patterns. For a nanotube of a given structure, the electron scattering amplitude from the carbon nanotube is first described analytically in closed form using the helical diffraction theory. From a known structure as given by the chiral indices (u, v), its electron diffraction pattern can be calculated and understood. The reverse problem, i.e. assignment of the chiral indices from an electron diffraction pattern of a carbon nanotube, is approached from the relationship between the electron scattering intensity distribution and the chiral indices (u, v). We show that electron diffraction patterns can provide an accurate and unambiguous assignment of the chiral indices of carbon nanotubes. The chiral indices (u, v) can be read indiscriminately with a high accuracy from the intensity distribution on the principal layer lines in an electron diffraction pattern. The symmetry properties of electron diffraction from carbon nanotubes and the electron diffraction from deformed carbon nanotubes are also discussed in detail. It is shown that 2mm symmetry is always preserved for single-walled carbon nanotubes, but it can break down for multiwalled carbon nanotubes under some special circumstances

  20. Adhered Supported Carbon Nanotubes

    International Nuclear Information System (INIS)

    Johnson, Dale F.; Craft, Benjamin J.; Jaffe, Stephen M.

    2001-01-01

    Carbon nanotubes (NTs) in excess of 200 μm long are grown by catalytic pyrolysis of hydrocarbon vapors. The nanotubes grow continuously without the typical extinction due to catalyst encapsulation. A woven metal mesh supports the nanotubes creating a metal supported nanotube (MSNT) structure. The 140 μm wide mesh openings are completely filled by 70 nm diameter multiwalled nanotubes (MWNTs). The MWNTs are straight, uniform and highly crystalline. Their wall thickness is about 10 nm (30 graphite layers). The adherent NTs are not removed from the support in a Scotch tape pull test. A 12.5 cm 2 capacitor made from two MSNT structures immersed in 1 M KCl has a capacitance of 0.35 F and an equivalent series resistance of 0.18 Ω. Water flows through the MSNT at a flow velocity of 1 cm/min with a pressure drop of 15 inches of water. With the support removed, the MWNTs naturally form a carbon nanocomposite (CNC) paper with a specific area of 80 m 2 /gm, a bulk density of 0.21 g/cm 3 , an open pore fraction of 0.81, and a resistivity of 0.16 Ω-cm

  1. Formation of carbon nanotubes on an amorphous Ni{sub 25}Ta{sub 58}N{sub 17} alloy film by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gromov, D. G.; Dubkov, S. V., E-mail: sv.dubkov@gmail.com [National Research University of Electronic Technology MIET (Russian Federation); Pavlov, A. A. [Russian Academy of Sciences, Institute of Nanotechnologies of Microelectronics (Russian Federation); Skorik, S. N. [Technological Center Research and Production Complex (Russian Federation); Trifonov, A. Yu. [Lukin Scientific Research Institute of Physical Problems (Russian Federation); Kirilenko, E. P.; Shulyat’ev, A. S. [National Research University of Electronic Technology MIET (Russian Federation); Shaman, Yu. P. [Technological Center Research and Production Complex (Russian Federation); Rygalin, B. N. [National Research University of Electronic Technology MIET (Russian Federation)

    2016-12-15

    It is shown that it is possible to grow carbon nanotubes on the surface of an amorphous Ni–Ta–N metal alloy film with a low Ni content (~25 at %) by chemical deposition from acetylene at temperature 400–800°C. It is established that the addition of nitrogen into the Ni–Ta alloy composition is favorable for the formation of tantalum nitride and the expulsion of Ni clusters, which act as a catalyst of the growth of carbon nanotubes, onto the surface. From Raman spectroscopy studies, it is found that, as the temperature of synthesis is raised, the quality of nanotubes is improved.

  2. Diffusion measurements by Raman spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Shapiro, Alexander; Berg, Rolf W.

    Poster "Diffusion measurements by Raman spectroscopy", See poster at http://www.kemi.dtu.dk/~ajo/rolf/petroday2004.ppt......Poster "Diffusion measurements by Raman spectroscopy", See poster at http://www.kemi.dtu.dk/~ajo/rolf/petroday2004.ppt...

  3. Imaging with extrinsic Raman labels

    NARCIS (Netherlands)

    Sijtsema, N M; Duindam, J J; Puppels, G J; Otto, C; Greve, J

    1996-01-01

    In two separate examples we demonstrate the use of extrinsic Raman scattering probes for imaging of biological samples. First, the distribution of cholesterol in a rat eye Lens is determined with the use of the Raman scattered light from filipin, a molecule which binds specifically to cholesterol.

  4. Raman scattering tensors of tyrosine.

    Science.gov (United States)

    Tsuboi, M; Ezaki, Y; Aida, M; Suzuki, M; Yimit, A; Ushizawa, K; Ueda, T

    1998-01-01

    Polarized Raman scattering measurements have been made of a single crystal of L-tyrosine by the use of a Raman microscope with the 488.0-nm exciting beam from an argon ion laser. The L-tyrosine crystal belongs to the space group P2(1)2(1)2(1) (orthorhombic), and Raman scattering intensities corresponding to the aa, bb, cc, ab and ac components of the crystal Raman tensor have been determined for each prominent Raman band. A similar set of measurements has been made of L-tyrosine-d4, in which four hydrogen atoms on the benzene ring are replaced by deuterium atoms. The effects of NH3-->ND3 and OH-->OD on the Raman spectrum have also been examined. In addition, depolarization ratios of some bands of L-tyrosine in aqueous solutions of pH 13 and pH 1 were examined. For comparison with these experimental results, on the other hand, ab initio molecular orbital calculations have been made of the normal modes of vibration and their associated polarizability oscillations of the L-tyrosine molecule. On the basis of these experimental data and by referring to the results of the calculations, discussions have been presented on the Raman tensors associated to some Raman bands, including those at 829 cm-1 (benzene ring breathing), 642 cm-1 (benzene ring deformation), and 432 cm-1 (C alpha-C beta-C gamma bending).

  5. Miniature Raman spectrometer development

    Science.gov (United States)

    Bonvallet, Joseph; Auz, Bryan; Rodriguez, John; Olmstead, Ty

    2018-02-01

    The development of techniques to rapidly identify samples ranging from, molecule and particle imaging to detection of high explosive materials, has surged in recent years. Due to this growing want, Raman spectroscopy gives a molecular fingerprint, with no sample preparation, and can be done remotely. These systems can be small, compact, lightweight, and with a user interface that allows for easy use and sample identification. Ocean Optics Inc. has developed several systems that would meet all these end user requirements. This talk will describe the development of different Ocean Optics Inc miniature Raman spectrometers. The spectrometer on a phone (SOAP) system was designed using commercial off the shelf (COTS) components, in a rapid product development cycle. The footprint of the system measures 40x40x14 mm (LxWxH) and was coupled directly to the cell phone detector camera optics. However, it gets roughly only 40 cm-1 resolution. The Accuman system is the largest (290x220X100 mm) of the three, but uses our QEPro spectrometer and get 7-11 cm-1 resolution. Finally, the HRS-30 measuring 165x85x40 mm is a combination of the other two systems. This system uses a modified EMBED spectrometer and gets 7-12 cm-1 resolution. Each of these units uses a peak matching algorithm that then correlates the results to the pre-loaded and customizable spectral libraries.

  6. Passive UHF RFID Tag for Multispectral Assessment

    Directory of Open Access Journals (Sweden)

    Pablo Escobedo

    2016-07-01

    Full Text Available This work presents the design, fabrication, and characterization of a passive printed radiofrequency identification tag in the ultra-high-frequency band with multiple optical sensing capabilities. This tag includes five photodiodes to cover a wide spectral range from near-infrared to visible and ultraviolet spectral regions. The tag antenna and circuit connections have been screen-printed on a flexible polymeric substrate. An ultra-low-power microcontroller-based switch has been included to measure the five magnitudes issuing from the optical sensors, providing a spectral fingerprint of the incident electromagnetic radiation from ultraviolet to infrared, without requiring energy from a battery. The normalization procedure has been designed applying illuminants, and the entire system was tested by measuring cards from a colour chart and sensing fruit ripening.

  7. Flavour tagging at the future linear collider

    International Nuclear Information System (INIS)

    Hansen, S.X.

    2003-01-01

    High performance flavour tagging of jets containing heavy flavours is crucial for the studies planned for the future high energy e + e - Linear Collider (LC). Pixel detectors have proven to provide very powerful flavour identification, for this reason the Linear Collider Flavour Identification collaboration has decided to concentrate its R and D work for the future LC on a Charged Coupled Device pixel vertex detector, and study the flavour tagging performance of the design to optimize it. In this work we first evaluate the basic tracking performance. We then estimate the flavour tagging performance of the present detector layout, using a neural network approach. We conclude by studying the energy dependence of the performance

  8. Femtosecond Broadband Stimulated Raman Spectroscopy

    International Nuclear Information System (INIS)

    Lee, Soo-Y; Yoon, Sagwoon; Mathies, Richard A

    2006-01-01

    Femtosecond broadband stimulated Raman spectroscopy (FSRS) is a new technique where a narrow bandwidth picosecond Raman pump pulse and a red-shifted broadband femtosecond Stokes probe pulse (with or without time delay between the pulses) act on a sample to produce a high resolution Raman gain spectrum with high efficiency and speed, free from fluorescence background interference. It can reveal vibrational structural information and dynamics of stationary or transient states. Here, the quantum picture for femtosecond broadband stimulated Raman spectroscopy (FSRS) is used to develop the semiclassical coupled wave theory of the phenomenon and to derive an expression for the measurable Raman gain in FSRS. The semiclassical theory is applied to study the dependence of lineshapes in FSRS on the pump-probe time delay and to deduce vibrational dephasing times in cyclohexane in the ground state

  9. Blood analysis by Raman spectroscopy.

    Science.gov (United States)

    Enejder, Annika M K; Koo, Tae-Woong; Oh, Jeankun; Hunter, Martin; Sasic, Slobodan; Feld, Michael S; Horowitz, Gary L

    2002-11-15

    Concentrations of multiple analytes were simultaneously measured in whole blood with clinical accuracy, without sample processing, using near-infrared Raman spectroscopy. Spectra were acquired with an instrument employing nonimaging optics, designed using Monte Carlo simulations of the influence of light-scattering-absorbing blood cells on the excitation and emission of Raman light in turbid medium. Raman spectra were collected from whole blood drawn from 31 individuals. Quantitative predictions of glucose, urea, total protein, albumin, triglycerides, hematocrit, and hemoglobin were made by means of partial least-squares (PLS) analysis with clinically relevant precision (r(2) values >0.93). The similarity of the features of the PLS calibration spectra to those of the respective analyte spectra illustrates that the predictions are based on molecular information carried by the Raman light. This demonstrates the feasibility of using Raman spectroscopy for quantitative measurements of biomolecular contents in highly light-scattering and absorbing media.

  10. Theranostic Gold Nanoantennas for Simultaneous Multiplexed Raman Imaging of Immunomarkers and Photothermal Therapy.

    Science.gov (United States)

    Webb, Joseph A; Ou, Yu-Chuan; Faley, Shannon; Paul, Eden P; Hittinger, Joseph P; Cutright, Camden C; Lin, Eugene C; Bellan, Leon M; Bardhan, Rizia

    2017-07-31

    In this study, we demonstrate the theranostic capability of actively targeted, site-specific multibranched gold nanoantennas (MGNs) in triple-negative breast cancer (TNBC) cells in vitro. By utilizing multiplexed surface-enhanced Raman scattering (SERS) imaging, enabled by the narrow peak widths of Raman signatures, we simultaneously targeted immune checkpoint receptor programmed death ligand 1 (PDL1) and the epidermal growth factor receptor (EGFR) overexpressed in TNBC cells. A 1:1 mixture of MGNs functionalized with anti-PDL1 antibodies and Raman tag 5,5-dithio-bis-(2-nitrobenzoic acid) (DTNB) and MGNs functionalized with anti-EGFR antibodies and Raman tag para -mercaptobenzoic acid ( p MBA) were incubated with the cells. SERS imaging revealed a cellular traffic map of MGN localization by surface binding and receptor-mediated endocytosis, enabling targeted diagnosis of both biomarkers. Furthermore, cells incubated with anti-EGFR- p MBA-MGNs and illuminated with an 808 nm laser for 15 min at 4.7 W/cm 2 exhibited photothermal cell death only within the laser spot (indicated by live/dead cell fluorescence assay). Therefore, this study not only provides an optical imaging platform that can track immunomarkers with spatiotemporal control but also demonstrates an externally controlled light-triggered therapeutic approach enabling receptor-specific treatment with biocompatible theranostic nanoprobes.

  11. Soldering of Nanotubes onto Microelectrodes

    DEFF Research Database (Denmark)

    Madsen, Dorte Nørgaard; Mølhave, Kristian; Mateiu, Ramona Valentina

    2003-01-01

    Suspended bridges of individual multiwalled carbon nanotubes were fabricated inside a scanning electron microscope by soldering the nanotube onto microelectrodes with highly conducting gold-carbon material. By the decomposition of organometallic vapor with the electron beam, metal-containing sold...... bonds were consistently found to be mechanically stronger than the carbon nanotubes.......Suspended bridges of individual multiwalled carbon nanotubes were fabricated inside a scanning electron microscope by soldering the nanotube onto microelectrodes with highly conducting gold-carbon material. By the decomposition of organometallic vapor with the electron beam, metal-containing solder...... bonds were formed at the intersection of the nanotube and the electrodes. Current-voltage curves indicated metallic conduction of the nanotubes, with resistances in the range of 9-29 kOmega. Bridges made entirely of the soldering material exhibited resistances on the order of 100 Omega, and the solder...

  12. Spectroscopic investigations on oxidized multi-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Anandhi, C. M. S.; Premkumar, S.; Asath, R. Mohamed; Mathavan, T.; Benial, A. Milton Franklin, E-mail: miltonfranklin@yahoo.com [Department of Physics, N.M.S.S.V.N. College, Madurai-625 019, Tamil Nadu (India)

    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.

  13. Three-dimensional polypyrrole-derived carbon nanotube framework for dye adsorption and electrochemical supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Xin, Shengchang; Yang, Na; Gao, Fei [School of Life Sciences, State Key Laboratory of Coordination Chemistry and Collaborative Innovation Center of Chemistry for Life Sciences, Institute of Chemistry and BioMedical Sciences, Nanjing University, Nanjing 210093 (China); Zhao, Jing, E-mail: jingzhao@nju.edu.cn [School of Life Sciences, State Key Laboratory of Coordination Chemistry and Collaborative Innovation Center of Chemistry for Life Sciences, Institute of Chemistry and BioMedical Sciences, Nanjing University, Nanjing 210093 (China); Li, Liang, E-mail: msell08@163.com [School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan 430073 (China); Teng, Chao, E-mail: tengc@pkusz.edu.cn [Guangdong Provincial Key Laboratory of Nano-Micro Materials Research, School of Chemical Biology & Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055 (China)

    2017-08-31

    Highlights: • Three-dimensional polypyrrole-derived carbon nanotube frameworks are prepared. • They display outstanding absorption capacity (609 mg g{sup −1}) towards methylene blue. • They possess high specific capacitance (167 F g{sup −1}) and good rate capability (64%). • They have excellent cycling performance with no capacitance loss over 1000 cycles. - Abstract: Three-dimensional carbon nanotube frameworks have been prepared via pyrolysis of polypyrrole nanotube aerogels that are synthesized by the simultaneous self-degraded template synthesis and hydrogel assembly followed by freeze-drying. The microstructure and composition of the materials are investigated by thermal gravimetric analysis, Raman spectrum, X-ray photoelectron spectroscopy, transmission electron microscopy, and specific surface analyzer. The results confirm the formation of three-dimensional carbon nanotube frameworks with low density, high mechanical properties, and high specific surface area. Compared with PPy aerogel precursor, the as-prepared three-dimensional carbon nanotube frameworks exhibit outstanding adsorption capacity towards organic dyes. Moreover, electrochemical tests show that the products possess high specific capacitance, good rate capability and excellent cycling performance with no capacitance loss over 1000 cycles. These characteristics collectively indicate the potential of three-dimensional polypyrrole-derived carbon nanotube framework as a promising macroscopic device for the applications in environmental and energy storages.

  14. Template-free synthesis of fully collapsed carbon nanotubes and graphene nanoribbons by chemical vapor deposition

    International Nuclear Information System (INIS)

    Zhang, Yong-Xing; Jia, Yong

    2015-01-01

    Highlights: • Commercial Fe 2 O 3 and Al 2 O 3 powders were chosen to prepare Fe 2 O 3 /Al 2 O 3 catalyst. • Fully collapsed carbon nanotubes and graphene nanoribbons were synthesized through the catalytic decomposition of methane at 900 °C. • The formation mechanism of the fully collapsed carbon nanotubes was revealed. - Abstract: Fe 2 O 3 /Al 2 O 3 catalyst was prepared by simply calcining the mixture of commercial Fe 2 O 3 and Al 2 O 3 powders at 1000 °C. The obtained Fe 2 O 3 /Al 2 O 3 catalyst shows high efficiency for the synthesis of fully collapsed carbon nanotubes and graphene nanoribbons through the catalytic decomposition of methane at 900 °C. The yield of the fully collapsed carbon nanotubes and graphene nanoribbons was 19.5 wt%. Field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and thermal gravimetric analysis were used to characterize the products. A tip-growth mechanism for the fully collapsed carbon nanotubes was suggested based on the SEM and TEM images of products produced at the initial stage. The break through of the catalyst particle from graphite layers resulted in the crack and then cut open of the fully collapsed carbon nanotubes, which further resulted in the formation of the graphene nanoribbons.

  15. Synthesis of boron nitride nanotubes by an oxide-assisted chemical method

    International Nuclear Information System (INIS)

    Singhal, S. K.; Srivastava, A. K.; Gupta, Anil K.; Chen, Z. G.

    2010-01-01

    We report a new method for the synthesis of boron nitride (BN) nanotubes employing a two-step process in which some oxides have found to catalyze the growth of BN nanotubes. In the first step, a precursor containing B-N-O-Fe/Mg was prepared by ball milling a mixture of B, B 2 O 3 , Fe 2 O 3 and MgO (1:7:2:1 mass ratio) in NH 3 for 3 h. BN nanotubes (diameter: 20-100 nm) were grown in the second step from this precursor by isothermal annealing at 1,350 o C in NH 3 for about 4 h. XRD, SEM and HR-TEM studies elucidated the spindle-like morphology of these nanotubes of hexagonal crystal structure. The Raman spectrum showed the peak broadening and shifts to higher frequency. The present method showed that some oxides assisted the growth of BN nanotubes. A possible reaction mechanism on the formation of BN nanotubes in the presence of these oxides is discussed.

  16. Fast synthesis of multilayer carbon nanotubes from camphor oil as an energy storage material.

    Science.gov (United States)

    TermehYousefi, Amin; Bagheri, Samira; Shinji, Kawasaki; Rouhi, Jalal; Rusop Mahmood, Mohamad; Ikeda, Shoichiro

    2014-01-01

    Among the wide range of renewable energy sources, the ever-increasing demand for electricity storage represents an emerging challenge. Utilizing carbon nanotubes (CNTs) for energy storage is closely being scrutinized due to the promising performance on top of their extraordinary features. In this work, well-aligned multilayer carbon nanotubes were successfully synthesized on a porous silicon (PSi) substrate in a fast process using renewable natural essential oil via chemical vapor deposition (CVD). Considering the influx of vaporized multilayer vertical carbon nanotubes (MVCNTs) to the PSi, the diameter distribution increased as the flow rate decreased in the reactor. Raman spectroscopy results indicated that the crystalline quality of the carbon nanotubes structure exhibits no major variation despite changes in the flow rate. Fourier transform infrared (FT-IR) spectra confirmed the hexagonal structure of the carbon nanotubes because of the presence of a peak corresponding to the carbon double bond. Field emission scanning electron microscopy (FESEM) images showed multilayer nanotubes, each with different diameters with long and straight multiwall tubes. Moreover, the temperature programmed desorption (TPD) method has been used to analyze the hydrogen storage properties of MVCNTs, which indicates that hydrogen adsorption sites exist on the synthesized multilayer CNTs.

  17. Fast Synthesis of Multilayer Carbon Nanotubes from Camphor Oil as an Energy Storage Material

    Directory of Open Access Journals (Sweden)

    Amin TermehYousefi

    2014-01-01

    Full Text Available Among the wide range of renewable energy sources, the ever-increasing demand for electricity storage represents an emerging challenge. Utilizing carbon nanotubes (CNTs for energy storage is closely being scrutinized due to the promising performance on top of their extraordinary features. In this work, well-aligned multilayer carbon nanotubes were successfully synthesized on a porous silicon (PSi substrate in a fast process using renewable natural essential oil via chemical vapor deposition (CVD. Considering the influx of vaporized multilayer vertical carbon nanotubes (MVCNTs to the PSi, the diameter distribution increased as the flow rate decreased in the reactor. Raman spectroscopy results indicated that the crystalline quality of the carbon nanotubes structure exhibits no major variation despite changes in the flow rate. Fourier transform infrared (FT-IR spectra confirmed the hexagonal structure of the carbon nanotubes because of the presence of a peak corresponding to the carbon double bond. Field emission scanning electron microscopy (FESEM images showed multilayer nanotubes, each with different diameters with long and straight multiwall tubes. Moreover, the temperature programmed desorption (TPD method has been used to analyze the hydrogen storage properties of MVCNTs, which indicates that hydrogen adsorption sites exist on the synthesized multilayer CNTs.

  18. Fast Synthesis of Multilayer Carbon Nanotubes from Camphor Oil as an Energy Storage Material

    Science.gov (United States)

    TermehYousefi, Amin; Bagheri, Samira; Shinji, Kawasaki; Rouhi, Jalal; Rusop Mahmood, Mohamad; Ikeda, Shoichiro

    2014-01-01

    Among the wide range of renewable energy sources, the ever-increasing demand for electricity storage represents an emerging challenge. Utilizing carbon nanotubes (CNTs) for energy storage is closely being scrutinized due to the promising performance on top of their extraordinary features. In this work, well-aligned multilayer carbon nanotubes were successfully synthesized on a porous silicon (PSi) substrate in a fast process using renewable natural essential oil via chemical vapor deposition (CVD). Considering the influx of vaporized multilayer vertical carbon nanotubes (MVCNTs) to the PSi, the diameter distribution increased as the flow rate decreased in the reactor. Raman spectroscopy results indicated that the crystalline quality of the carbon nanotubes structure exhibits no major variation despite changes in the flow rate. Fourier transform infrared (FT-IR) spectra confirmed the hexagonal structure of the carbon nanotubes because of the presence of a peak corresponding to the carbon double bond. Field emission scanning electron microscopy (FESEM) images showed multilayer nanotubes, each with different diameters with long and straight multiwall tubes. Moreover, the temperature programmed desorption (TPD) method has been used to analyze the hydrogen storage properties of MVCNTs, which indicates that hydrogen adsorption sites exist on the synthesized multilayer CNTs. PMID:25258714

  19. A Privacy Model for RFID Tag Ownership Transfer

    Directory of Open Access Journals (Sweden)

    Xingchun Yang

    2017-01-01

    Full Text Available The ownership of RFID tag is often transferred from one owner to another in its life cycle. To address the privacy problem caused by tag ownership transfer, we propose a tag privacy model which captures the adversary’s abilities to get secret information inside readers, to corrupt tags, to authenticate tags, and to observe tag ownership transfer processes. This model gives formal definitions for tag forward privacy and backward privacy and can be used to measure the privacy property of tag ownership transfer scheme. We also present a tag ownership transfer scheme, which is privacy-preserving under the proposed model and satisfies the other common security requirements, in addition to achieving better performance.

  20. Top tagging with deep neural networks [Vidyo

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    Recent literature on deep neural networks for top tagging has focussed on image based techniques or multivariate approaches using high level jet substructure variables. Here, we take a sequential approach to this task by using anordered sequence of energy deposits as training inputs. Unlike previous approaches, this strategy does not result in a loss of information during pixelization or the calculation of high level features. We also propose new preprocessing methods that do not alter key physical quantities such as jet mass. We compare the performance of this approach to standard tagging techniques and present results evaluating the robustness of the neural network to pileup.

  1. A Comparative Study of the Effect of MgO and CaCO3 as Support Materials in the Synthesis of Carbon Nanotubes with Fe/Co as Catalyst

    Directory of Open Access Journals (Sweden)

    Ezekiel D. Dikio

    2014-01-01

    Full Text Available A comparative study of the effect of magnesium oxide and calcium carbonate as support material in the synthesis of carbon nanotubes using the catalyst Fe/Co is presented. The synthesized carbon nanotubes were characterized with Raman spectroscopy, scanning electron spectroscopy (SEM, high-resolution transmission electron microscopy (HRTEM, X-ray diffraction spectroscopy (XRD, and energy dispersive spectroscopy (EDS. The morphology of the carbon nanotubes synthesized with magnesium oxide as support material gives rise to carbon nanotubes with consistent and well-defined structure unlike that synthesized with calcium carbonate. The ID/IG ratio of synthesized carbon nanotubes (CNTs was 0.8544 for magnesium oxide supported compared to 0.8501 for calcium carbonate supported carbon nanotube.

  2. Nickel nanoparticle decorated graphene for highly selective isolation of polyhistidine-tagged proteins

    Science.gov (United States)

    Liu, Jia-Wei; Yang, Ting; Ma, Lin-Yu; Chen, Xu-Wei; Wang, Jian-Hua

    2013-12-01

    Nickel nanoparticle decorated graphene (GP-Ni) is prepared by one-pot hydrothermal reduction of graphene oxide and nickel cations by hydrazine hydrate in the presence of poly(sodium-p-styrenesulfonate) (PSS). The GP-Ni hybrid is characterized by XRD, TEM, SEM, XPS, Raman and FT-IR spectra, demonstrating the formation of poly-dispersed nickel nanoparticles with an average size of 83 nm attached on the surface of graphene sheets. The GP-Ni hybrid exhibits ferromagnetic behavior with a magnetization saturation of 31.1 emu g-1 at 10 000 Oersted (Oe). The GP-Ni also possesses favorable stability in aqueous medium and rapid magnetic response to an external magnetic field. These make it a novel magnetic adsorbent for the separation/isolation of His6-tagged recombinant proteins from a complex sample matrix (cell lysate). The targeted protein species is captured onto the surface of the GP-Ni hybrid via specific metal affinity force between polyhistidine groups and nickel nanoparticles. The SDS-PAGE assay indicates highly selective separation of His6-tagged Smt A from cell lysate. The GP-Ni hybrid displays favorable performance on the separation/isolation of His6-tagged recombinant proteins with respect to the commercial NTA-Ni2+ column.

  3. Photon-tagged and B-meson-tagged b-jet production at the LHC

    Directory of Open Access Journals (Sweden)

    Jinrui Huang

    2015-11-01

    Full Text Available Tagged jet measurements in high energy hadronic and nuclear reactions provide constraints on the energy and parton flavor origin of the parton shower that recoils against the tagging particle. Such additional insight can be especially beneficial in illuminating the mechanisms of heavy flavor production in proton–proton collisions at the LHC and their modification in the heavy ion environment, which are not fully understood. With this motivation, we present theoretical results for isolated-photon-tagged and B-meson-tagged b-jet production at sNN=5.1 TeV for comparison to the upcoming lead–lead data. We find that photon-tagged b-jets exhibit smaller momentum imbalance shift in nuclear matter, and correspondingly smaller energy loss, than photon-tagged light flavor jets. Our results show that B-meson tagging is most effective in ensuring that the dominant fraction of recoiling jets originate from prompt b-quarks. Interestingly, in this channel the large suppression of the cross section is not accompanied by a significant momentum imbalance shift.

  4. A competitive binding between O2 and epoxy with carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Hsin-Jung Tsai

    2017-09-01

    Full Text Available Simulation and observation reveal a competitive binding between O2 and epoxy with carbon nanotubes. Air absorption limits tube-polymer interacting coverage and weakens the van der Waals forces. As O2 is removed the tube-polymer strongly couples and coupling is conformed in a parallel fashion. Electron microscopy verifies tubes to be weakly bonded with polymer and band-shifts of raman arise from air pressure acting on C-C bonds.

  5. Characterization of Carbon Nanotubes Deposited in Microwave Torch at Atmospheric Pressure

    Czech Academy of Sciences Publication Activity Database

    Zajíčková, L.; Eliáš, M.; Jašek, O.; Kučerová, Z.; Synek, P.; Matějková, Jiřina; Kadlečíková, M.; Klementová, Mariana; Buršík, Jiří; Vojačková, A.

    2007-01-01

    Roč. 4, Suppl. 1 (2007), S245-S249 ISSN 1612-8850 R&D Projects: GA ČR(CZ) GA202/05/0607 Institutional research plan: CEZ:AV0Z20650511; CEZ:AV0Z40320502; CEZ:AV0Z20410507 Keywords : carbon nanotubes * microwave torch * atmospheric pressure * scanning electron microscopy * Raman spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.132, year: 2007

  6. Ferromagnetic resonance of cobalt nanoparticles used as a catalyst for the carbon nanotubes synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M. [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, Almaty (Kazakhstan); Institute of Physics and Technology, Almaty (Kazakhstan)], E-mail: duraia_physics@yahoo.com; Abdullin, Kh.A. [Institute of Physics and Technology, Almaty (Kazakhstan)

    2009-12-15

    Catalyst is considered to be the most crucial parameter for the growth of carbon nanotubes. In this work we study the ferromagnetic resonance (FMR) spectra of the catalyst nanoclusters. Moreover we report for the first time the angle FMR studies of catalyst particles with and without CNT layer. The dependencies of the FMR spectra, X-ray diffraction (XRD) patterns, Raman spectra and morphology of the CNT layers on the growth conditions are discussed.

  7. A comparative evaluation of three methods used to tag South African ...

    African Journals Online (AJOL)

    Tagging effects and loss rates of 60 Roman Chrysoblephus laticeps tagged with dart tags with barbs (D-tags), T-bar filaments (T-tags) and visible implant fluorescent elastomer (VIFE) tags were investigated. The fish were tagged and monitored in a controlled tank experiment over a period of 198 days. Application technique ...

  8. Conjugation of cytochrome c with hydrogen titanate nanotubes: novel conformational state with implications for apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Moumita; Mazumdar, Shyamalava [Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Chatterjee, Sriparna; Das, Tanmay; Bhattacharyya, Somnath; Ayyub, Pushan, E-mail: somnath@tifr.res.in, E-mail: pushan@tifr.res.in, E-mail: shyamal@tifr.res.in [Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

    2011-10-14

    We show that hydrogen titanate (H{sub 2}Ti{sub 3}O{sub 7}) nanotubes form strongly associated reversible nano-bio-conjugates with the vital respiratory protein, cytochrome c. Resonance Raman spectroscopy along with direct electrochemical studies indicate that in this nano-bio-conjugate, cytochrome c exists in an equilibrium of two conformational states with distinctly different formal redox potentials and coordination geometries of the heme center. The nanotube-conjugated cytochrome c also showed enhanced peroxidase activity similar to the membrane-bound protein that is believed to be an apoptosis initiator. This suggests that such a nanotube-cytochrome c conjugate may be a good candidate for cancer therapy applications.

  9. Growth of carbon nanotubes by Fe-catalyzed chemical vapor processes on silicon-based substrates

    Science.gov (United States)

    Angelucci, Renato; Rizzoli, Rita; Vinciguerra, Vincenzo; Fortuna Bevilacqua, Maria; Guerri, Sergio; Corticelli, Franco; Passini, Mara

    2007-03-01

    In this paper, a site-selective catalytic chemical vapor deposition synthesis of carbon nanotubes on silicon-based substrates has been developed in order to get horizontally oriented nanotubes for field effect transistors and other electronic devices. Properly micro-fabricated silicon oxide and polysilicon structures have been used as substrates. Iron nanoparticles have been obtained both from a thin Fe film evaporated by e-gun and from iron nitrate solutions accurately dispersed on the substrates. Single-walled nanotubes with diameters as small as 1 nm, bridging polysilicon and silicon dioxide “pillars”, have been grown. The morphology and structure of CNTs have been characterized by SEM, AFM and Raman spectroscopy.

  10. Exploring the alignment of carbon nanotubes dispersed in a liquid crystal matrix using coplanar electrodes

    International Nuclear Information System (INIS)

    Volpati, D.; Massey, M. K.; Kotsialos, A.; Qaiser, F.; Pearson, C.; Tiburzi, G.; Zeze, D. A.; Petty, M. C.; Johnson, D. W.; Coleman, K. S.

    2015-01-01

    We report on the use of a liquid crystalline host medium to align single-walled carbon nanotubes in an electric field using an in-plane electrode configuration. Electron microscopy reveals that the nanotubes orient in the field with a resulting increase in the DC conductivity in the field direction. Current versus voltage measurements on the composite show a nonlinear behavior, which was modelled by using single-carrier space-charge injection. The possibility of manipulating the conductivity pathways in the same sample by applying the electrical field in different (in-plane) directions has also been demonstrated. Raman spectroscopy indicates that there is an interaction between the nanotubes and the host liquid crystal molecules that goes beyond that of simple physical mixing

  11. Langmuir hydrogen dissociation approach in radiolabeling carbon nanotubes and graphene oxide

    International Nuclear Information System (INIS)

    Badun, Gennadii A.; Chernysheva, Maria G.; Eremina, Elena A.; Egorov, Alexander V.; Grigorieva, Anastasia V.

    2016-01-01

    Carbon-based nanomaterials have piqued the interest of several researchers. At the same time, radioactive labeling is a powerful tool for studying processes in different systems, including biological and organic; however, the introduction of radioactive isotopes into carbon-based nanomaterial remains a great challenge. We have used the Langmuir hydrogen dissociation method to introduce tritium in single-walled carbon nanotubes and graphene oxide. The technique allows us to achieve a specific radioactivity of 107 and 27 Ci/g for single-layer graphene oxide and single-walled carbon nanotubes, respectively. Based on the analysis of characteristic Raman modes at 1350 and 1580 cm -1 , a minimal amount of structural changes to the nanomaterials due to radiolabeling was observed. The availability of a simple, nondestructive, and economic technique for the introduction of radiolabels to single-walled carbon nanotubes and graphene oxide will ultimately expand the applicability of these materials.

  12. Quantum interference effects on the intensity of the G modes in double-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Tran, Huy Nam; Blancon, Jean-Christophe Robert; Arenal, Raul

    2017-01-01

    The effects of quantum interferences on the excitation dependence of the intensity of G modes have been investigated on single-walled carbon nanotubes [Duque et al., Phys. Rev. Lett.108, 117404 (2012)]. In this work, by combining optical absorption spectroscopy and Raman scattering on individual index identified double-walled carbon nanotubes, we examine the experimental excitation dependence of the intensity of longitudinal optical and transverse optical G modes of the constituent inner and outer single-walled carbon nanotubes. The observed striking dependencies are understood in terms of quantum interference effects. Considering such effects, the excitation dependence of the different components of the G modes permit to unambiguously assign each of them as originating from the longitudinal or transverse G modes of inner and outer tubes.

  13. Langmuir hydrogen dissociation approach in radiolabeling carbon nanotubes and graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Badun, Gennadii A.; Chernysheva, Maria G.; Eremina, Elena A.; Egorov, Alexander V. [Lomonosov Moscow State Univ. (Russian Federation). Dept. of Chemistry; Grigorieva, Anastasia V. [Lomonosov Moscow State Univ., Moscow (Russian Federation). Dept. of Materials Science

    2016-11-01

    Carbon-based nanomaterials have piqued the interest of several researchers. At the same time, radioactive labeling is a powerful tool for studying processes in different systems, including biological and organic; however, the introduction of radioactive isotopes into carbon-based nanomaterial remains a great challenge. We have used the Langmuir hydrogen dissociation method to introduce tritium in single-walled carbon nanotubes and graphene oxide. The technique allows us to achieve a specific radioactivity of 107 and 27 Ci/g for single-layer graphene oxide and single-walled carbon nanotubes, respectively. Based on the analysis of characteristic Raman modes at 1350 and 1580 cm{sup -1}, a minimal amount of structural changes to the nanomaterials due to radiolabeling was observed. The availability of a simple, nondestructive, and economic technique for the introduction of radiolabels to single-walled carbon nanotubes and graphene oxide will ultimately expand the applicability of these materials.

  14. Preparation of carbon nanotubes with different morphology by microwave plasma enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M. [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan); Mansurov, Zulkhair [Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Tokmoldin, S.Zh. [Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan)

    2010-04-15

    In this work we present a part of our results about the preparation of carbon nanotube with different morphologies by using microwave plasma enhanced chemical vapour deposition MPECVD. Well aligned, curly, carbon nanosheets, coiled carbon sheets and carbon microcoils have been prepared. We have investigated the effect of the different growth condition parameters such as the growth temperature, pressure and the hydrogen to methane flow rate ratio on the morphology of the carbon nanotubes. The results showed that there is a great dependence of the morphology of carbon nanotubes on these parameters. The yield of the carbon microcoils was high when the growth temperature was 700 C. There is a linear relation between the growth rate and the methane to hydrogen ratio. The effect of the gas pressure on the CNTs was also studied. Our samples were investigated by scanning electron microscope and Raman spectroscopy (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Carbon nanotube/platinum nanoparticle nanocomposites: preparation, characterization and application in electro oxidation of alcohols

    International Nuclear Information System (INIS)

    Kalinke, Adir H.; Zarbin, Aldo J. G.

    2014-01-01

    The synthesis and characterization of different platinum nanoparticle/ carbon nanotube nanocomposite samples are described along with the application of these nanocomposites as electrocatalysts for alcohol oxidation. Samples were prepared by a biphasic system in which platinum nanoparticles (Pt-NPs) are synthesized in situ in contact with a carbon nanotube (CNT) dispersion. Variables including platinum precursor/CNT ratio, previous chemical treatment of carbon nanotubes, and presence or absence of a capping agent were evaluated and correlated with the characteristic of the synthesized materials. Samples were characterized by Raman spectroscopy, X-ray diffraction, thermogravimetric analysis and transmission electron microscopy. Glassy carbon electrodes were modified by the nanocomposite samples and evaluated as electrocatalysts for alcohol oxidation. Current densities of 56.1 and 79.8/104.7 mA cm -2 were determined for the oxidation of methanol and ethanol, respectively. (author)

  16. Top Tagging by Deep Learning Algorithm

    CERN Document Server

    Akil, Ali

    2015-01-01

    In this report I will show the application of a deep learning algorithm on a Monte Carlo simulation sample to test its performance in tagging hadronic decays of boosted top quarks and compare what we get with the results of the application of some other algorithms.

  17. Semantic Tagging with Deep Residual Networks

    NARCIS (Netherlands)

    Bjerva, Johannes; Plank, Barbara; Bos, Johan

    2016-01-01

    We propose a novel semantic tagging task, semtagging, tailored for the purpose of multilingual semantic parsing, and present the first tagger using deep residual networks (ResNets). Our tagger uses both word and character representations and includes a novel residual bypass architecture. We evaluate

  18. Krypton tagging velocimetry of an underexpanded jet.

    Science.gov (United States)

    Parziale, N J; Smith, M S; Marineau, E C

    2015-06-01

    In this work, we present the excitation/emission strategy, experimental setup, and results of an implementation of krypton tagging velocimetry (KTV). KTV is performed as follows: (i) seed a base flow with krypton; (ii) photosynthesize metastable krypton atoms with a frequency-doubled dye laser to form the tagged tracer; (iii) record the translation of the tagged metastable krypton by imaging the laser-induced fluorescence (LIF) that is produced with an additional dye laser. The principle strength of KTV, relative to other tagging velocimetry techniques, is the use of a chemically inert tracer. KTV results are presented for an underexpanded jet of three mixtures of varying Kr/N2 concentration. It is demonstrated that KTV can be used in gas mixtures of relatively low krypton mole fraction (0.5% Kr/99.5% N2), and the KTV data from that experiment are found to be in good agreement with an empirical fit found in the literature. We find that KTV is useful to perform instantaneous velocity measurements with metastable krypton as a chemically inert, dilute, long-lifetime tracer in gas-phase flows.

  19. Policy administration in tag-based authorization

    NARCIS (Netherlands)

    Etalle, Sandro; Hinrichs, Timothy L.; Lee, Adam J.; Trivellato, Daniel; Zannone, Nicola

    2013-01-01

    Tag-Based Authorization (TBA) is a hybrid access control model that combines the ease of use of extensional access control models with the expressivity of logic-based formalisms. The main limitation of TBA is that it lacks support for policy administration. More precisely, it does not allow

  20. Electronic excitation induced modifications in elongated iron nanoparticle encapsulated multiwalled carbon nanotubes under ion irradiation

    Science.gov (United States)

    Saikiran, V.; Bazylewski, P.; Sameera, I.; Bhatia, Ravi; Pathak, A. P.; Prasad, V.; Chang, G. S.

    2018-05-01

    Multi-wall carbon nanotubes (MWCNT) filled with Fe nanorods were shown to have contracted and deformed under heavy ion irradiation. In this study, 120 MeV Ag and 80 MeV Ni ion irradiation was performed to study the deformation and defects induced in iron filled MWCNT under heavy ion irradiation. The structural modifications induced due to electronic excitation by ion irradiation were investigated employing high-resolution transmission electron microscopy, micro-Raman scattering experiments, and synchrotron-based X-ray absorption and emission spectroscopy. We understand that the ion irradiation causes modifications in the Fe nanorods which result in compressions and expansions of the nanotubes, and in turn leads to the buckling of MWCNT. The G band of the Raman spectra shifts slightly towards higher wavenumber and the shoulder G‧ band enhances with the increase of ion irradiation fluence, where the buckling wavelength depends on the radius 'r' of the nanotubes as exp[(r)0.5]. The intensity ratio of the D to G Raman modes initially decreases at the lowest fluence, and then it increases with the increase in ion fluence. The electron diffraction pattern and the high resolution images clearly show the presence of ion induced defects on the walls of the tube and encapsulated iron nanorods.

  1. Continuous carbon nanotube reinforced composites.

    Science.gov (United States)

    Ci, L; Suhr, J; Pushparaj, V; Zhang, X; Ajayan, P M

    2008-09-01

    Carbon nanotubes are considered short fibers, and polymer composites with nanotube fillers are always analogues of random, short fiber composites. The real structural carbon fiber composites, on the other hand, always contain carbon fiber reinforcements where fibers run continuously through the composite matrix. With the recent optimization in aligned nanotube growth, samples of nanotubes in macroscopic lengths have become available, and this allows the creation of composites that are similar to the continuous fiber composites with individual nanotubes running continuously through the composite body. This allows the proper utilization of the extreme high modulus and strength predicted for nanotubes in structural composites. Here, we fabricate such continuous nanotube polymer composites with continuous nanotube reinforcements and report that under compressive loadings, the nanotube composites can generate more than an order of magnitude improvement in the longitudinal modulus (up to 3,300%) as well as damping capability (up to 2,100%). It is also observed that composites with a random distribution of nanotubes of same length and similar filler fraction provide three times less effective reinforcement in composites.

  2. Scanning angle Raman spectroscopy: Investigation of Raman scatter enhancement techniques for chemical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Matthew W. [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    This thesis outlines advancements in Raman scatter enhancement techniques by applying evanescent fields, standing-waves (waveguides) and surface enhancements to increase the generated mean square electric field, which is directly related to the intensity of Raman scattering. These techniques are accomplished by employing scanning angle Raman spectroscopy and surface enhanced Raman spectroscopy. A 1064 nm multichannel Raman spectrometer is discussed for chemical analysis of lignin. Extending dispersive multichannel Raman spectroscopy to 1064 nm reduces the fluorescence interference that can mask the weaker Raman scattering. Overall, these techniques help address the major obstacles in Raman spectroscopy for chemical analysis, which include the inherently weak Raman cross section and susceptibility to fluorescence interference.

  3. Detection of latent prints by Raman imaging

    Science.gov (United States)

    Lewis, Linda Anne [Andersonville, TN; Connatser, Raynella Magdalene [Knoxville, TN; Lewis, Sr., Samuel Arthur

    2011-01-11

    The present invention relates to a method for detecting a print on a surface, the method comprising: (a) contacting the print with a Raman surface-enhancing agent to produce a Raman-enhanced print; and (b) detecting the Raman-enhanced print using a Raman spectroscopic method. The invention is particularly directed to the imaging of latent fingerprints.

  4. Frequency shifts in stimulated Raman scattering

    International Nuclear Information System (INIS)

    Zinth, W.; Kaiser, W.

    1980-01-01

    The nonresonant contributions to the nonlinear susceptibility chisup(()3) produce a frequency chirp during stimulated Raman scattering. In the case of transient stimulated Raman scattering, the spectrum of the generated Stokes pulse is found at higher frequencies than expected from spontaneous Raman data. The frequency difference can be calculated from the theory of stimulated Raman scattering. (orig.)

  5. Raman spectra of lithium compounds

    Science.gov (United States)

    Gorelik, V. S.; Bi, Dongxue; Voinov, Y. P.; Vodchits, A. I.; Gorshunov, B. P.; Yurasov, N. I.; Yurasova, I. I.

    2017-11-01

    The paper is devoted to the results of investigating the spontaneous Raman scattering spectra in the lithium compounds crystals in a wide spectral range by the fibre-optic spectroscopy method. We also present the stimulated Raman scattering spectra in the lithium hydroxide and lithium deuteride crystals obtained with the use of powerful laser source. The symmetry properties of the lithium hydroxide, lithium hydroxide monohydrate and lithium deuteride crystals optical modes were analyzed by means of the irreducible representations of the point symmetry groups. We have established the selection rules in the Raman and infrared absorption spectra of LiOH, LiOH·H2O and LiD crystals.

  6. Growth of carbon nanotubes in arc plasma treated graphite disc: microstructural characterization and electrical conductivity study

    Science.gov (United States)

    Nayak, B. B.; Sahu, R. K.; Dash, T.; Pradhan, S.

    2018-03-01

    Circular graphite discs were treated in arc plasma by varying arcing time. Analysis of the plasma treated discs by field emission scanning electron microscope revealed globular grain morphologies on the surfaces, but when the same were observed at higher magnification and higher resolution under transmission electron microscope, growth of multiwall carbon nanotubes of around 2 nm diameter was clearly seen. In situ growth of carbon nanotube bundles/bunches consisting of around 0.7 nm tube diameter was marked in the case of 6 min treated disc surface. Both the untreated and the plasma treated graphite discs were characterized by X-ray diffraction, energy dispersive spectra of X-ray, X-ray photoelectron spectroscopy, transmission electron microscopy, micro Raman spectroscopy and BET surface area measurement. From Raman spectra, BET surface area and microstructure observed in transmission electron microscope, growth of several layers of graphene was identified. Four-point probe measurements for electrical resistivity/conductivity of the graphite discs treated under different plasma conditions showed significant increase in conductivity values over that of untreated graphite conductivity value and the best result, i.e., around eightfold increase in conductivity, was observed in the case of 6 min plasma treated sample exhibiting carbon nanotube bundles/bunches grown on disc surface. By comparing the microstructures of the untreated and plasma treated graphite discs, the electrical conductivity increase in graphite disc is attributed to carbon nanotubes (including bundles/bunches) growth on disc surface by plasma treatment.

  7. Control of the Diameter and Chiral Angle Distributions during Production of Single-Wall Carbon Nanotubes

    Science.gov (United States)

    Nikolaev, Pavel

    2009-01-01

    Many applications of single wall carbon nanotubes (SWCNT), especially in microelectronics, will benefit from use of certain (n,m) nanotube types (metallic, small gap semiconductor, etc.) Especially fascinating is the possibility of quantum conductors that require metallic armchair nanotubes. However, as produced SWCNT samples are polydisperse, with many (n,m) types present and typical approx.1:2 metal/semiconductor ratio. Nanotube nucleation models predict that armchair nuclei are energetically preferential due to formation of partial triple bonds along the armchair edge. However, nuclei can not reach any meaningful thermal equilibrium in a rapidly expanding and cooling plume of carbon clusters, leading to polydispersity. In the present work, SWCNTs were produced by a pulsed laser vaporization (PLV) technique. The carbon vapor plume cooling rate was either increased by change in the oven temperature (expansion into colder gas), or decreased via "warm-up" with a laser pulse at the moment of nucleation. The effect of oven temperature and "warm-up" on nanotube type population was studied via photoluminescence, UV-Vis-NIR absorption and Raman spectroscopy. It was found that reduced temperatures leads to smaller average diameters, progressively narrower diameter distributions, and some preference toward armchair structures. "Warm-up" shifts nanotube population towards arm-chair structures as well, but the effect is small. Possible improvement of the "warm-up" approach to produce armchair SWCNTs will be discussed. These results demonstrate that PLV production technique can provide at least partial control over the nanotube (n,m) population. In addition, these results have implications for the understanding the nanotube nucleation mechanism in the laser oven.

  8. The use of tags and tag clouds to discern credible content in online health message forums.

    Science.gov (United States)

    O'Grady, Laura; Wathen, C Nadine; Charnaw-Burger, Jill; Betel, Lisa; Shachak, Aviv; Luke, Robert; Hockema, Stephen; Jadad, Alejandro R

    2012-01-01

    Web sites with health-oriented content are potentially harmful if inaccurate or inappropriate medical information is used to make health-related decisions. Checklists, rating systems and guidelines have been developed to help people determine what is credible, but recent Internet technologies emphasize applications that are collaborative in nature, including tags and tag clouds, where site users 'tag' or label online content, each using their own labelling system. Concepts such as the date, reference, author, testimonial and quotations are considered predictors of credible content. An understanding of these descriptive tools, how they relate to the depiction of credibility and how this relates to overall efforts to label data in relation to the semantic web has yet to emerge. This study investigates how structured (pre-determined) and unstructured (user-generated) tags and tag clouds with a multiple word search feature are used by participants to assess credibility of messages posted in online message forums. The targeted respondents were those using web sites message forums for disease self-management. We also explored the relevancy of our findings to the labelling or indexing of data in the context of the semantic web. Diabetes was chosen as the content area in this study, since (a) this is a condition with increasing prevalence and (b) diabetics have been shown to actively use the Internet to manage their condition. From January to March 2010 participants were recruited using purposive sampling techniques. A screening instrument was used to determine eligibility. The study consisted of a demographic and computer usage survey, a series of usability tests and an interview. We tested participants (N=22) on two scenarios, each involving tasks that assessed their ability to tag content and search using a tag cloud that included six structured credibility terms (statistics, date, reference, author, testimonial and quotations). MORAE Usability software (version 3

  9. Mass Transport Through Carbon Nanotube-Polystyrene Bundles

    Science.gov (United States)

    Lin, Rongzhou; Tran, Tuan

    2016-05-01

    Carbon nanotubes have been widely used as test channels to study nanofluidic transport, which has been found to have distinctive properties compared to transport of fluids in macroscopic channels. A long-standing challenge in the study of mass transport through carbon nanotubes (CNTs) is the determination of flow enhancement. Various experimental investigations have been conducted to measure the flow rate through CNTs, mainly based on either vertically aligned CNT membranes or individual CNTs. Here, we proposed an alternative approach that can be used to quantify the mass transport through CNTs. This is a simple method relying on the use of carbon nanotube-polystyrene bundles, which are made of CNTs pulled out from a vertically aligned CNT array and glued together by polystyrene. We experimentally showed by using fluorescent tagging that the composite bundles allowed measureable and selective mass transport through CNTs. This type of composite bundle may be useful in various CNT research areas as they are simple to fabricate, less likely to form macroscopic cracks, and offer a high density of CNT pores while maintaining the aligned morphology of CNTs.

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

    Science.gov (United States)

    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

    2012-01-01

    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. PMID:27877482

  11. Carbon Nanotubes Growth by CVD on Graphite Fibers

    Science.gov (United States)

    Zhu, Shen; Su, Ching-Hua; Cochrane, J. C.; Lehoczky, S. L.; Muntele, I.; Ila, D.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Due to the superior electrical and mechanical properties of carbon nanotubes (CNT), synthesizing CNT on various substances for electronics devices and reinforced composites have been engaged in many efforts for applications. This presentation will illustrate CNT synthesized on graphite fibers by thermal CVD. On the fiber surface, iron nanoparticles as catalysts for CNT growth are coated. The growth temperature ranges from 600 to 1000 C and the pressure ranges from 100 Torr to one atmosphere. Methane and hydrogen gases with methane content of 10% to 100% are used for the CNT synthesis. At high growth temperatures (greater than or equal to 900 C), the rapid inter-diffusion of the transition metal iron on the graphite surface results in the rough fiber surface without any CNT grown on it. When the growth temperature is relative low (650-800 C), CNT with catalytic particles on the nanotube top ends are fabricated on the graphite surface. (Methane and hydrogen gases with methane content of 10% to 100% are used for the CNT synthesis.) (By measuring the samples) Using micro Raman spectroscopy in the breath mode region, single-walled or multi-walled CNT (MWCNT), depending on growth concentrations, are found. Morphology, length and diameter of these MWCNT are determined by scanning electron microscopy and Raman spectroscopy. The detailed results of syntheses and characterizations will be discussed in the presentation.

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

    Directory of Open Access Journals (Sweden)

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

    2012-01-01

    Full Text Available 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.

  13. A Personalized Tag-Based Recommendation in Social Web Systems

    DEFF Research Database (Denmark)

    Durao, Frederico; Dolog, Peter

    2009-01-01

    -based recommender system which suggests similar Web pages based on the similarity of their tags from a Web 2.0 tagging application. The proposed approach extends the basic similarity calculus with external factors such as tag popularity, tag representativeness and the affinity between user and tag. In order...... to study and evaluate the recommender system, we have conducted an experiment involving 38 people from 12 countries using data from Del.icio.us , a social bookmarking web system on which users can share their personal bookmarks......Tagging activity has been recently identified as a potential source of knowledge about personal interests, preferences, goals, and other attributes known from user models. Tags themselves can be therefore used for finding personalized recommendations of items. In this paper, we present a tag...

  14. APPECT: An Approximate Backbone-Based Clustering Algorithm for Tags

    DEFF Research Database (Denmark)

    Zong, Yu; Xu, Guandong; Jin, Pin

    2011-01-01

    algorithm for Tags (APPECT). The main steps of APPECT are: (1) we execute the K-means algorithm on a tag similarity matrix for M times and collect a set of tag clustering results Z={C1,C2,…,Cm}; (2) we form the approximate backbone of Z by executing a greedy search; (3) we fix the approximate backbone...... as the initial tag clustering result and then assign the rest tags into the corresponding clusters based on the similarity. Experimental results on three real world datasets namely MedWorm, MovieLens and Dmoz demonstrate the effectiveness and the superiority of the proposed method against the traditional...... Agglomerative Clustering on tagging data, which possess the inherent drawbacks, such as the sensitivity of initialization. In this paper, we instead make use of the approximate backbone of tag clustering results to find out better tag clusters. In particular, we propose an APProximate backbonE-based Clustering...

  15. Observation of the low frequency vibrational modes of bacteriophage M13 in water by Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Tsen Shaw-Wei D

    2006-09-01

    Full Text Available Abstract Background Recently, a technique which departs radically from conventional approaches has been proposed. This novel technique utilizes biological objects such as viruses as nano-templates for the fabrication of nanostructure elements. For example, rod-shaped viruses such as the M13 phage and tobacco mosaic virus have been successfully used as biological templates for the synthesis of semiconductor and metallic nanowires. Results and discussion Low wave number (≤ 20 cm-1 acoustic vibrations of the M13 phage have been studied using Raman spectroscopy. The experimental results are compared with theoretical calculations based on an elastic continuum model and appropriate Raman selection rules derived from a bond polarizability model. The observed Raman mode has been shown to belong to one of the Raman-active axial torsion modes of the M13 phage protein coat. Conclusion It is expected that the detection and characterization of this low frequency vibrational mode can be used for applications in nanotechnology such as for monitoring the process of virus functionalization and self-assembly. For example, the differences in Raman spectra can be used to monitor the coating of virus with some other materials and nano-assembly process, such as attaching a carbon nanotube or quantum dots.

  16. Raman Excitation Profile of the G-band Enhancement in Twisted Bilayer Graphene

    Science.gov (United States)

    Eliel, G. S. N.; Ribeiro, H. B.; Sato, K.; Saito, R.; Lu, Chun-Chieh; Chiu, Po-Wen; Fantini, C.; Righi, A.; Pimenta, M. A.

    2017-12-01

    A resonant Raman study of twisted bilayer graphene (TBG) samples with different twisting angles using many different laser lines in the visible range is presented. The samples were fabricated by CVD technique and transferred to Si/SiO2 substrates. The Raman excitation profiles of the huge enhancement of the G-band intensity for a group of different TBG flakes were obtained experimentally, and the analysis of the profiles using a theoretical expression for the Raman intensities allowed us to obtain the energies of the van Hove singularities generated by the Moiré patterns and the lifetimes of the excited state of the Raman process. Our results exhibit a good agreement between experimental and calculated energies for van Hove singularities and show that the lifetime of photoexcited carrier does not depend significantly on the twisting angle in the range intermediate angles ( 𝜃 between 10∘ and 15∘). We observed that the width of the resonance window (Γ ≈ 250 meV) is much larger than the REP of the Raman modes of carbon nanotubes, which are also enhanced by resonances with van Hove singularities.

  17. Raman spectroscopy of white wines.

    Science.gov (United States)

    Martin, Coralie; Bruneel, Jean-Luc; Guyon, François; Médina, Bernard; Jourdes, Michael; Teissedre, Pierre-Louis; Guillaume, François

    2015-08-15

    The feasibility of exploiting Raman scattering to analyze white wines has been investigated using 3 different wavelengths of the incoming laser radiation in the near-UV (325 nm), visible (532 nm) and near infrared (785 nm). To help in the interpretation of the Raman spectra, the absorption properties in the UV-visible range of two wine samples as well as their laser induced fluorescence have also been investigated. Thanks to the strong intensity enhancement of the Raman scattered light due to electronic resonance with 325 nm laser excitation, hydroxycinnamic acids may be detected and analyzed selectively. Fructose and glucose may also be easily detected below ca. 1000 cm(-1). This feasibility study demonstrates the potential of the Raman spectroscopic technique for the analysis of white wines. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. All-Fiber Raman Probe

    DEFF Research Database (Denmark)

    Brunetti, Anna Chiara

    by means of fiber components. Assuming the possibility to use a fiber laser with a fundamental radiation at 1064nm, in-fiber efficient second harmonic generation is achieved by optically poling the core of the waveguide delivering the excitation light to the sample. In this way, Raman spectroscopy...... in the visible range can be performed. The simultaneous delivery of the excitation light and collection of the Raman signal from the sample are achieved by means of a doubleclad fiber, whose core and inner cladding act as \\independent" transmission channels. A double-clad fiber coupler allows for the recovery...... of the collected Raman scattering from the inner-cladding region of the double-clad fiber, thus replacing the bulk dichroic component normally used to demultiplex the pump and Raman signal. A tunable Rayleigh-rejection filter based on a liquid filled-photonic bandgap fiber is also demonstrated in this work...

  19. Group Discovery in a CollaborativeTagging System

    OpenAIRE

    Chen, Zijian

    2007-01-01

    Tagging refers to the process of adding metadata to describe things by usingone or several words. Collaborative Tagging systems, which allow different webusers to tag web content like weblogs, pictures, and bookmarks and so on, haverecently gained great popularity on internet. There are already a greatvariety of debates on internet of the advantages and disadvantages ofcollaborative tagging systems from the aspect of information organizing. Inthis paper, we primarily focus on a collaborative ...

  20. 3D scaffolds from vertically aligned carbon nanotubes/poly(methyl methacrylate) composites via atom transfer radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Tebikachew, Behabtu; Magina, Sandra [CICECO, Department of Chemistry, University of Aveiro (Portugal); Mata, Diogo; Oliveira, Filipe J.; Silva, Rui F. [CICECO, Department of Materials and Ceramic Engineering, University of Aveiro (Portugal); Barros-Timmons, Ana, E-mail: anabarros@ua.pt [CICECO, Department of Chemistry, University of Aveiro (Portugal)

    2015-01-15

    Vertically aligned carbon nanotubes (VACNTs) synthesized by Thermal Chemical Vapour Deposition (TCVD) were modified using an Ar:O{sub 2} (97:3) plasma to generate oxygen-containing functional groups on the surface for subsequent modification. X-ray photo-emission spectroscopy (XPS) and micro-Raman analyses confirmed the grafting of those functional groups onto the surface of the nanotubes as well as the removal of amorphous carbon produced and deposited on the VACNT forests during the CVD process. The plasma treated VACNT forests were further modified with 2-bromo-2-methylpropionyl bromide, an atom transfer radical polymerization (ATRP) initiator, to grow poly(methyl methacrylate) (PMMA) chains from the forests via ATRP. Scanning transmission electron microscopy (STEM) of the ensuing VACNT/PMMA composites confirmed the coating of the nanotube forests with the PMMA polymer. 3D scaffolds of polymeric composites with honeycomb like structure were then obtained. Compressive tests have shown that the VACNT/PMMA composite has higher compressive strength than the pristine forest. - Highlights: • Vertically aligned carbon nanotubes (VACNTs) were synthesized and plasma modified. • X-ray photo-emission and Raman spectroscopies confirmed the VACNTs modification. • Poly(methyl methacrylate) chains were grown via ATRP from the VACNTs. • STEM of the VACNT/PMMA composites confirmed that PMMA surrounds the nanotubes. • VACNT/PMMA composite has higher compressive strength compared to the pristine forest.

  1. 3D scaffolds from vertically aligned carbon nanotubes/poly(methyl methacrylate) composites via atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Tebikachew, Behabtu; Magina, Sandra; Mata, Diogo; Oliveira, Filipe J.; Silva, Rui F.; Barros-Timmons, Ana

    2015-01-01

    Vertically aligned carbon nanotubes (VACNTs) synthesized by Thermal Chemical Vapour Deposition (TCVD) were modified using an Ar:O 2 (97:3) plasma to generate oxygen-containing functional groups on the surface for subsequent modification. X-ray photo-emission spectroscopy (XPS) and micro-Raman analyses confirmed the grafting of those functional groups onto the surface of the nanotubes as well as the removal of amorphous carbon produced and deposited on the VACNT forests during the CVD process. The plasma treated VACNT forests were further modified with 2-bromo-2-methylpropionyl bromide, an atom transfer radical polymerization (ATRP) initiator, to grow poly(methyl methacrylate) (PMMA) chains from the forests via ATRP. Scanning transmission electron microscopy (STEM) of the ensuing VACNT/PMMA composites confirmed the coating of the nanotube forests with the PMMA polymer. 3D scaffolds of polymeric composites with honeycomb like structure were then obtained. Compressive tests have shown that the VACNT/PMMA composite has higher compressive strength than the pristine forest. - Highlights: • Vertically aligned carbon nanotubes (VACNTs) were synthesized and plasma modified. • X-ray photo-emission and Raman spectroscopies confirmed the VACNTs modification. • Poly(methyl methacrylate) chains were grown via ATRP from the VACNTs. • STEM of the VACNT/PMMA composites confirmed that PMMA surrounds the nanotubes. • VACNT/PMMA composite has higher compressive strength compared to the pristine forest

  2. Triplet State Resonance Raman Spectroscopy

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter; Jensen, N. H.; Pagsberg, Palle Bjørn

    1978-01-01

    Makes the first report on the resonance Raman spectrum of a molecule in its triplet state generated by pulse radiolysis. A solution of 0.01 mol dm-3 of p-terphenyl in benzene was studied......Makes the first report on the resonance Raman spectrum of a molecule in its triplet state generated by pulse radiolysis. A solution of 0.01 mol dm-3 of p-terphenyl in benzene was studied...

  3. Heating by the Raman instability

    International Nuclear Information System (INIS)

    Estabrook, K.G.; Kruer, W.L.

    1980-01-01

    Computer simulations are presented of the reflection and heating due to stimulated Raman backscatter of intense laser light in large regions of underdense plasma. The heated electron distribution is found to be approximately a Maxwellian of temperature (m/sub e//2)v/sub p/ 2 , where v/sub p/ is the phase velocity of the electron plasma wave. A simple model of the reflection is presented. Raman may cause a pre-heat problem with large laser fusion reactor targets

  4. Learning tag relevance by neighbor voting for social image retrieval

    NARCIS (Netherlands)

    Li, X.; Snoek, C.G.M.; Worring, M.

    2008-01-01

    Social image retrieval is important for exploiting the increasing amounts of amateur-tagged multimedia such as Flickr images. Since amateur tagging is known to be uncontrolled, ambiguous, and personalized, a fundamental problem is how to reliably interpret the relevance of a tag with respect to the

  5. Incorporating user motivations to design for video tagging

    NARCIS (Netherlands)

    van Velsen, Lex Stefan; Melenhorst, M.S.

    2009-01-01

    User video tagging can enhance the indexing of large collections of videos, or can provide the basis for personalizing output. However, before the benefits of tagging can be reaped, users must be motivated to provide videos with tags. This article describes a two-stage study that aimed at collecting

  6. Tags in Domain-Specific Sites - New Information?

    DEFF Research Database (Denmark)

    Steinhauer, Jeremy; Delcambre, Lois M.L.; Maier, David

    2011-01-01

    If researchers use tags in retrieval applications they might assume, implicitly, that tags represent novel information, e.g., when they attribute performance improvement in their retrieval algorithm(s) to the use of tags. In this work, we investigate whether this assumption is true. We focus on t...

  7. Bus and Tag Terminators for IBM system/360

    CERN Multimedia

    Control units were connected to the channels with "Bus and Tag" cable pairs. The bus cables carried the address and data information and the tag cables identified what data was on the bus. There were three general types of bus-and-tag cables produced by IBM.

  8. The Effects of Target Audience on Social Tagging

    Science.gov (United States)

    Alsarhan, Hesham

    2013-01-01

    Online social bookmarking systems allow users to assign tags (i.e., keywords) to represent the content of resources. Research on the effects of target audience on social tagging suggests that taggers select different tags for themselves, their community (e.g., family, friends, colleagues), and the general public (Panke & Gaiser, 2009; Pu &…

  9. Key mediators modulating TAG synthesis and accumulation in ...

    African Journals Online (AJOL)

    the key mediators on TAG synthesis and accumulation, among which diacylglycerol acyltransferases (DGATs) is discussed for its clear role in TAG amount and composition. Furthermore TAG-accosiated proteins called oleosins are also discussed in depth due to their determination on the amount and size of oil bodies.

  10. Exploiting phase measurements of EPC Gen2 RFID tags

    NARCIS (Netherlands)

    Huiting, J.; Flisijn, Hubert; Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria

    2013-01-01

    This paper presents a 2d localization system for UHF RFID tags. By measuring the phase between the transmitted continuous wave and received backscatter from the tag at different frequencies, it is possible to estimate the distance between the reader and tag. By determining distance estimates to

  11. Synaptic Tagging, Evaluation of Memories, and the Distal Reward Problem

    Science.gov (United States)

    Papper, Marc; Kempter, Richard; Leibold, Christian

    2011-01-01

    Long-term synaptic plasticity exhibits distinct phases. The synaptic tagging hypothesis suggests an early phase in which synapses are prepared, or "tagged," for protein capture, and a late phase in which those proteins are integrated into the synapses to achieve memory consolidation. The synapse specificity of the tags is consistent with…

  12. Electrostatically Induced Carbon Nanotube Alignment for Polymer Composite Applications

    Science.gov (United States)

    Chapkin, Wesley Aaron

    We have developed a non-invasive technique utilizing polarized Raman spectroscopy to measure changes in carbon nanotube (CNT) alignment in situ and in real time in a polymer matrix. With this technique, we have confirmed the prediction of faster alignment for CNTs in higher electric fields. Real-time polarized Raman spectroscopy also allows us to demonstrate the loss of CNT alignment that occurs after the electric field is removed, which reveals the need for fast polymerization steps or the continued application of the aligning force during polymerization to lock in CNT alignment. Through a study on the effect of polymer viscosity on the rate of CNT alignment, we have determined that shear viscosity serves as the controlling mechanism for CNT rotation. This finding matches literature modeling of rigid rod mobility in a polymer melt and demonstrates that the rotational mobility of CNTs can be explained by a continuum model even though the diameters of single-walled CNTs are 1-2 nm. The viscosity dependence indicates that the manipulation of temperature (and indirectly viscosity) will have a direct effect on the rate of CNT alignment, which could prove useful in expediting the manufacturing of CNT-reinforced composites cured at elevated temperatures. Using real-time polarized Raman spectroscopy, we also demonstrate that electric fields of various strengths lead not only to different speeds of CNT rotation but also to different degrees of alignment. We hypothesize that this difference in achievable alignment results from discrete populations of nanotubes based on their length. The results are then explained by balancing the alignment energy for a given electric field strength with the randomizing thermal energy of the system. By studying the alignment dynamics of different CNT length distributions, we show that different degrees of alignment achieved as a function of the applied electric field strength are directly related to the square of the nanotube length. This

  13. Distribution and clearance of PEG-single-walled carbon nanotube cancer drug delivery vehicles in mice.

    Science.gov (United States)

    Bhirde, Ashwin A; Patel, Sachin; Sousa, Alioscka A; Patel, Vyomesh; Molinolo, Alfredo A; Ji, Youngmi; Leapman, Richard D; Gutkind, J Silvio; Rusling, James F

    2010-12-01

    To study the distribution and clearance of polyethylene glycol (PEG)-ylated single-walled carbon nanotube (SWCNTs) as drug delivery vehicles for the anticancer drug cisplatin in mice. PEG layers were attached to SWCNTs and dispersed in aqueous media and characterized using dynamic light scattering, scanning transmission electron microscopy and Raman spectroscopy. Cytotoxicity was assessed in vitro using Annexin-V assay, and the distribution and clearance pathways in mice were studied by histological staining and Raman spectroscopy. Efficacy of PEG-SWCNT-cisplatin for tumor growth inhibition was studied in mice. PEG-SWCNTs were efficiently dispersed in aqueous media compared with controls, and did not induce apoptosis in vitro. Hematoxylin and eosin staining, and Raman bands for SWCNTs in tissues from several vital organs from mice injected intravenously with nanotube bioconjugates revealed that control SWCNTs were lodged in lung tissue as large aggregates compared with the PEG-SWCNTs, which showed little or no accumulation. Characteristic SWCNT Raman bands in feces revealed the presence of bilary or renal excretion routes. Attachment of cisplatin on bioconjugates was visualized with Z-contrast scanning transmission electron microscopy. PEG-SWCNT-cisplatin with the attached targeting ligand EGF successfully inhibited growth of head and neck tumor xenografts in mice. PEG-SWCNTs, as opposed to control SWCNTs, form more highly dispersed delivery vehicles that, when loaded with both cisplatin and EGF, inhibit growth of squamous cell tumors.

  14. Continuum theory for nanotube piezoelectricity.

    Science.gov (United States)

    Michalski, P J; Sai, Na; Mele, E J

    2005-09-09

    We develop and solve a continuum theory for the piezoelectric response of one-dimensional nanotubes and nanowires, and apply the theory to study electromechanical effects in boron-nitride nanotubes. We find that the polarization of a nanotube depends on its aspect ratio, and a dimensionless constant specifying the ratio of the strengths of the elastic and electrostatic interactions. The solutions of the model as these two parameters are varied are discussed. The theory is applied to estimate the electric potential induced along the length of a boron-nitride nanotube in response to a uniaxial stress.

  15. Mechanical properties of carbon nanotubes

    Science.gov (United States)

    Salvetat, J.-P.; Bonard, J.-M.; Thomson, N. H.; Kulik, A. J.; Forró, L.; Benoit, W.; Zuppiroli, L.

    A variety of outstanding experimental results on the elucidation of the elastic properties of carbon nanotubes are fast appearing. These are based mainly on the techniques of high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM) to determine the Young's moduli of single-wall nanotube bundles and multi-walled nanotubes, prepared by a number of methods. These results are confirming the theoretical predictions that carbon nanotubes have high strength plus extraordinary flexibility and resilience. As well as summarising the most notable achievements of theory and experiment in the last few years, this paper explains the properties of nanotubes in the wider context of materials science and highlights the contribution of our research group in this rapidly expanding field. A deeper understanding of the relationship between the structural order of the nanotubes and their mechanical properties will be necessary for the development of carbon-nanotube-based composites. Our research to date illustrates a qualitative relationship between the Young's modulus of a nanotube and the amount of disorder in the atomic structure of the walls. Other exciting results indicate that composites will benefit from the exceptional mechanical properties of carbon nanotubes, but that the major outstanding problem of load transfer efficiency must be overcome before suitable engineering materials can be produced.

  16. Fabricating Copper Nanotubes by Electrodeposition

    Science.gov (United States)

    Yang, E. H.; Ramsey, Christopher; Bae, Youngsam; Choi, Daniel

    2009-01-01

    Copper tubes having diameters between about 100 and about 200 nm have been fabricated by electrodeposition of copper into the pores of alumina nanopore membranes. Copper nanotubes are under consideration as alternatives to copper nanorods and nanowires for applications involving thermal and/or electrical contacts, wherein the greater specific areas of nanotubes could afford lower effective thermal and/or electrical resistivities. Heretofore, copper nanorods and nanowires have been fabricated by a combination of electrodeposition and a conventional expensive lithographic process. The present electrodeposition-based process for fabricating copper nanotubes costs less and enables production of copper nanotubes at greater rate.

  17. Carbon Micronymphaea: Graphene on Vertically Aligned Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Jong Won Choi

    2013-01-01

    Full Text Available This paper describes the morphology of carbon nanomaterials such as carbon nanotube (CNT, graphene, and their hybrid structure under various operating conditions during a one-step synthesis via plasma-enhanced chemical vapor deposition (PECVD. We focus on the synthetic aspects of carbon hybrid material composed of heteroepitaxially grown graphene on top of a vertical array of carbon nanotubes, called carbon micronymphaea. We characterize the structural features of this unique nanocomposite by uses of electron microscopy and micro-Raman spectroscopy. We observe carbon nanofibers, poorly aligned and well-aligned vertical arrays of CNT sequentially as the growth temperature increases, while we always discover the carbon hybrids, called carbon micronymphaea, at specific cooling rate of 15°C/s, which is optimal for the carbon precipitation from the Ni nanoparticles in this study. We expect one-pot synthesized graphene-on-nanotube hybrid structure poses great potential for applications that demand ultrahigh surface-to-volume ratios with intact graphitic nature and directional electronic and thermal transports.

  18. Synthesis and characterization of conducting polyaniline 5-sulfosalicylate nanotubes

    International Nuclear Information System (INIS)

    Janosevic, Aleksandra; Ciric-Marjanovic, Gordana; Marjanovic, Budimir; Holler, Petr; Trchova, Miroslava; Stejskal, Jaroslav

    2008-01-01

    Conducting polyaniline 5-sulfosalicylate nanotubes and nanorods were synthesized by the template-free oxidative polymerization of aniline in aqueous solution of 5-sulfosalicylic acid, using ammonium peroxydisulfate as an oxidant. The effect of the molar ratio of 5-sulfosalicylic acid to aniline on the molecular structure, molecular weight distribution, morphology, and conductivity of polyaniline 5-sulfosalicylate was investigated. The nanotubes, which have a typical outer diameter of 100-250 nm, with an inner diameter of 10-60 nm, and a length extending from 0.4 to 1.5 μm, and the nanorods, with a diameter of 80-110 nm and a length of 0.5-0.7 μm, were observed by scanning and transmission electron microscopies. The presence of branched structures and phenazine units besides the ordinary polyaniline structural features was revealed by infrared and Raman spectroscopies. The stacking of low-molecular-weight substituted phenazines appears to play a major role in the formation of polyaniline nanorods. The precipitation-dissolution of oligoaniline templates as a key element in the formation of polyaniline nanotubes is proposed to explain the crucial influence of the initial pH of the reaction mixture and its decrease during the course of polymerization

  19. Synthesis and characterization of conducting polyaniline 5-sulfosalicylate nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Janosevic, Aleksandra; Ciric-Marjanovic, Gordana [Faculty of Physical Chemistry, University of Belgrade, Studentski Trg 12-16, 11001 Belgrade (Serbia); Marjanovic, Budimir [Centrohem, Vuka Karadzica bb, 22300 Stara Pazova (Serbia); Holler, Petr; Trchova, Miroslava; Stejskal, Jaroslav [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague 6 (Czech Republic)], E-mail: gordana@ffh.bg.ac.yu

    2008-04-02

    Conducting polyaniline 5-sulfosalicylate nanotubes and nanorods were synthesized by the template-free oxidative polymerization of aniline in aqueous solution of 5-sulfosalicylic acid, using ammonium peroxydisulfate as an oxidant. The effect of the molar ratio of 5-sulfosalicylic acid to aniline on the molecular structure, molecular weight distribution, morphology, and conductivity of polyaniline 5-sulfosalicylate was investigated. The nanotubes, which have a typical outer diameter of 100-250 nm, with an inner diameter of 10-60 nm, and a length extending from 0.4 to 1.5 {mu}m, and the nanorods, with a diameter of 80-110 nm and a length of 0.5-0.7 {mu}m, were observed by scanning and transmission electron microscopies. The presence of branched structures and phenazine units besides the ordinary polyaniline structural features was revealed by infrared and Raman spectroscopies. The stacking of low-molecular-weight substituted phenazines appears to play a major role in the formation of polyaniline nanorods. The precipitation-dissolution of oligoaniline templates as a key element in the formation of polyaniline nanotubes is proposed to explain the crucial influence of the initial pH of the reaction mixture and its decrease during the course of polymerization.

  20. Intermolecular dynamics studied by paramagnetic tagging

    Energy Technology Data Exchange (ETDEWEB)

    Xu Xingfu; Keizers, Peter H. J. [Leiden University, Institute of Chemistry (Netherlands); Reinle, Wolfgang; Hannemann, Frank; Bernhardt, Rita [Universitaet des Saarlandes, Naturwissenschaftlich-Technische Fakultaet III, Institut fuer Biochemie (Germany); Ubbink, Marcellus [Leiden University, Institute of Chemistry (Netherlands)], E-mail: m.ubbink@chem.leidenuniv.nl

    2009-04-15

    Yeast cytochrome c and bovine adrenodoxin form a dynamic electron transfer complex, which is a pure encounter complex. It is demonstrated that the dynamic nature of the interaction can readily be probed by using a rigid lanthanide tag attached to cytochrome c. The tag, Caged Lanthanide NMR Probe 5, induces pseudocontact shifts and residual dipolar couplings and does not perturb the binding interface. Due to the dynamics in the complex, residual dipolar couplings in adrenodoxin are very small. Simulation shows that cytochrome c needs to sample a large part of the surface of adrenodoxin to explain the small degree of alignment observed for adrenodoxin. The applied method provides a simple and straightforward way to observe dynamics in protein complexes or domain-domain mobility without the need for external alignment media.

  1. Intermolecular dynamics studied by paramagnetic tagging

    International Nuclear Information System (INIS)

    Xu Xingfu; Keizers, Peter H. J.; Reinle, Wolfgang; Hannemann, Frank; Bernhardt, Rita; Ubbink, Marcellus

    2009-01-01

    Yeast cytochrome c and bovine adrenodoxin form a dynamic electron transfer complex, which is a pure encounter complex. It is demonstrated that the dynamic nature of the interaction can readily be probed by using a rigid lanthanide tag attached to cytochrome c. The tag, Caged Lanthanide NMR Probe 5, induces pseudocontact shifts and residual dipolar couplings and does not perturb the binding interface. Due to the dynamics in the complex, residual dipolar couplings in adrenodoxin are very small. Simulation shows that cytochrome c needs to sample a large part of the surface of adrenodoxin to explain the small degree of alignment observed for adrenodoxin. The applied method provides a simple and straightforward way to observe dynamics in protein complexes or domain-domain mobility without the need for external alignment media

  2. Physics with tagged forward protons at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Yip,K.

    2009-08-30

    The physics reach of the STAR detector at RHIC has been extended to include elastic and inelastic diffraction measurements with tagged forward protons. This program has started at RHIC in p+p collisions with a special optics run of {beta}* {approx} 21 m at STAR, at the center-of-mass energy {radical}s = 200 GeV during the last week of the RHIC 2009 run.

  3. Emotional Mining: Tagging Emoticons to Online News

    Science.gov (United States)

    Kasinathan, Vinothini; Mustapha, Aida; Zhi Yong, Lee; Aida Zamnah, Z. A.

    2017-08-01

    This paper presents an emotion mining system, which assigns emoticons to newspaper articles into a pre-defined emotion category based on the underlying emotion in the news. Next, the system makes recommendation to the reader by tagging the news headline with the respective emoticons. Users are then able to decide whether to read the news based on the emoticons provided. The system also provides a filter for the users to choose the category of news to read following the emoticons.

  4. HPV Vaccine Safety PSA (:30) (No Tag)

    Centers for Disease Control (CDC) Podcasts

    In this 30 second public service announcement, a mother talks about the importance of protecting 11-12 year-old boys and girls with HPV vaccination. No CDC tag at the end. (Una madre habla sobre la importancia de proteger a los niños y las niñas de 11 a 12 años con la vacuna contra el VPH.)

  5. Scanning Cargo Containers with Tagged Neutrons

    International Nuclear Information System (INIS)

    Viesti, G.; Botosso, C.; Fabris, D.; Lunardon, M.; Moretto, S.; Nebbia, G.; Pesente, S.; Zenoni, A.; Donzella, A.; Perot, B.; Carasco, C.; Bernard, S.; Mariani, A.; Szabo, J.-L.; Sannie, G.; Valkovic, V.; Sudac, D.; Nad, K.; Peerani, P.; Sequeira, V.

    2007-01-01

    A new Tagged Neutron Inspection System (TNIS) able to detect illicit materials such as explosives and narcotics in cargo containers has been developed within the EURopean Illicit TRAfficing Countermeasures Kit (EURITRACK) project. After the R and D phase, the inspection portal has been installed and commissioned at the Rijeka seaport in Croatia, where it has been operated in connection with the existing X-ray scanner for a first two-month demonstration campaign. Results obtained are presented and discussed in this paper

  6. TAG Oil hunting elephants in New Zealand

    International Nuclear Information System (INIS)

    Anon.

    2005-01-01

    Calgary-based TAG Oil is an exploration company that manages 4.1 million acres of major producing oil and gas fields in New Zealand. The enormous Maui field, with 4 tcf of natural gas in place, has dominated the gas market in New Zealand by meeting nearly 90 per cent of the country's energy demand at costs much lower than world prices. However, the maturing field is in decline and will cease production by 2008. New gas field discoveries will only meet 60 per cent of the country's energy requirements for 5 additional years. Unless new large reserves of gas are discovered, the supply and demand situation will get worse. Lead time to place new production on-stream requires 5 to 10 years, which creates a large supply gap over the next decade. Public resistance to coal-fired power plants, new hydroelectric dams and nuclear power has left the country with no viable alternative to natural gas. TAG Oil has taken this unique opportunity to create value when gas demand is at its maximum and energy alternatives are at a minimum. This paper presented 8 reasons why New Zealand is a good place for petroleum investment. Most exploration has occurred in the Taranaki Basin, where only 130 exploration wells have been drilled. The rest of the sedimentary basins are essentially unexplored, although many exhibit oil seeps and have hydrocarbon potential. In 1998, an onshore gas discovery was made on the East Coast Basin. Sub-commercial discoveries have also been made in the offshore Canterbury and Great South basins. TAG Oil is focusing on shallow oil and gas pools in the Miocene reservoirs at Taranaki, as well as on deeper gas prospects in Tariki and Kapuni Sands. One of the challenges was a shortage of drilling rigs, so TAG is having a rig built in Calgary and shipped south. 2 figs

  7. Improved molecular fingerprint analysis employing multi-branched gold nanoparticles in conjunction with surface-enhanced Raman scattering

    Directory of Open Access Journals (Sweden)

    Johnston J

    2015-12-01

    Full Text Available Jencilin Johnston,1 Erik N Taylor,1,2 Richard J Gilbert,2 Thomas J Webster1,3 1Department of Chemical Engineering, 2Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, USA; 3Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia Abstract: Vibrational spectroscopy is a powerful analytical tool that assesses molecular properties based on spectroscopic signatures. In this study, the effect of gold nanoparticle morphology (spherical vs multi-branched was assessed for the characterization of a Raman signal (ie, molecular fingerprint that may be helpful for numerous medical applications. Multi-branched gold nanoparticles (MBAuNPs were fabricated using a green chemistry method which employed the reduction of gold ion solute by 2-[4-(2-hydroxyethyl-1-piperazyl] ethane sulfonic acid. Two types of reporter dyes, indocyanine (IR820 and IR792 and carbocyanine (DTTC [3,3'-diethylthiatricarbocyanine iodide] and DTDC [3,3'-diethylthiadicarbocyanine iodide], were functionalized to the surface of the MBAuNPs and stabilized with denatured bovine serum albumin, thus forming the surface-enhanced Raman spectroscopy tag. Fluorescein isothiocyanate-conjugated anti-epidermal growth factor receptor to the surface-enhanced Raman spectroscopy tags and the properties of the resulting conjugates were assessed through determination of the Raman signal. Using the MBAuNP Raman probes synthesized in this manner, we demonstrated that MBAuNP provided significantly more surface-enhanced Raman scattering signal when compared with the associated spherical gold nanoparticle of similar size and concentration. MBAuNP enhancements were retained in the surface-enhanced Raman spectroscopy tags complexed to anti-epidermal growth factor receptor, providing evidence that this could be a useful biological probe for enhanced Raman molecular fingerprinting. Furthermore, while utilizing IR820 as a novel reporter dye

  8. Single tag for total carbohydrate analysis.

    Science.gov (United States)

    Anumula, Kalyan Rao

    2014-07-15

    Anthranilic acid (2-aminobenzoic acid, 2-AA) has the remarkable property of reacting rapidly with every type of reducing carbohydrate. Reactivity of 2-AA with carbohydrates in aqueous solutions surpasses all other tags reported to date. This unique capability is attributed to the strategically located -COOH which accelerates Schiff base formation. Monosaccharides, oligosaccharides (N-, O-, and lipid linked and glycans in secretory fluids), glycosaminoglycans, and polysaccharides can be easily labeled with 2-AA. With 2-AA, labeling is simple in aqueous solutions containing proteins, peptides, buffer salts, and other ingredients (e.g., PNGase F, glycosidase, and transferase reaction mixtures). In contrast, other tags require relatively pure glycans for labeling in anhydrous dimethyl sulfoxide-acetic acid medium. Acidic conditions are known to cause desialylation, thus requiring a great deal of attention to sample preparation. Simpler labeling is achieved with 2-AA within 30-60 min in mild acetate-borate buffered solution. 2-AA provides the highest sensitivity and resolution in chromatographic methods for carbohydrate analysis in a simple manner. Additionally, 2-AA is uniquely qualified for quantitative analysis by mass spectrometry in the negative mode. Analyses of 2-AA-labeled carbohydrates by electrophoresis and other techniques have been reported. Examples cited here demonstrate that 2-AA is the universal tag for total carbohydrate analysis. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. RFID Label Tag Design for Metallic Surface Environments

    Directory of Open Access Journals (Sweden)

    Ki Hwan Eom

    2011-01-01

    Full Text Available This paper describes a metal mount RFID tag that works reliably on metallic surfaces. The method proposes the use of commercial label type RFID tags with 2.5 mm thick Styrofoam103.7 with a relative permittivity of 1.03 attached on the back of the tag. In order to verify the performance of the proposed method, we performed experiments on an electric transformer supply chain system. The experimental results showed that the proposed tags can communicate with readers from a distance of 2 m. The recognition rates are comparable to those of commercial metallic mountable tags.

  10. Carbon nanotube plane fastener

    Directory of Open Access Journals (Sweden)

    Kaori Hirahara

    2011-12-01

    Full Text Available We report a feature of carbon nanotubes (CNTs that arises when the surfaces of two vertically-aligned CNT brushes are pressed together. Adhesion between the CNTs creates a plane fastener-like device. Observations from scanning electron microscopy and measurements of adhesion properties indicate a device-dependence on CNT density and shape near the tip region. Among other applications, such fasteners have the potential to attach small components onto micron-sized electronic devices.

  11. Carbon nanotube network varactor

    International Nuclear Information System (INIS)

    Generalov, A A; Anoshkin, I V; Lioubtchenko, D V; Räisänen, A V; Erdmanis, M; Ovchinnikov, V; Nasibulin, A G

    2015-01-01

    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling. (paper)

  12. Systematic study on synthesis and purification of double-walled carbon nanotubes synthesized via CVD

    Science.gov (United States)

    Jedrzejewska, A.; Kalenczuk, R. J.; Mijowska, E.

    2011-12-01

    Carbon nanotubes have unique properties, such as thermal and electrical conductance, which could be useful in the fields of aerospace, microelectronics and biotechnology. However, these properties may vary widely depending on the dimensions, uniformity and purity of the nanotube. Nanotube samples typically contain a significant percentage of more allotropes forms of carbon as well as metal particles left over from catalysts used in manufacturing. Purity characterization of double-walled carbon nanotubes (DWCNTs) is an increasingly popular topic in the field of carbon nanotechnology. In this study, DWCNTs were synthesized in a catalytic reaction, using Fe:MgO as catalyst and methane or methane/ethanol as carbon feedstock for chemical vapor deposition (CVD). The addition of ethanol as carbon feedstock allowed to investigate the influence of oxygen on the sample quality. The purification of the as-produced material from the metallic particles and the catalyst support was performed by sonication in an acid solution. The influence of the duration of the acid treatment using ultrasound on the sample purity was investigated, and the optimal value of this parameter was found. Transmission electron microscopy (TEM) images confirmed the removal of impurities and served to elucidate the morphology of the samples. The purity of carbon nanotubes was analyzed using thermal gravimetric analysis (TGA). The Raman spectra of the samples, as a measure of the concentration of defects, were also reported.

  13. Characterization of carbon nanotubes grown on Fe70Pd30 film

    International Nuclear Information System (INIS)

    Khan, Zishan H.; Islam, S.S.; Kung, S.C.; Perng, T.P.; Khan, Samina; Tripathi, K.N.; Agarwal, Monika; Zulfequar, M.; Husain, M.

    2006-01-01

    Carbon nanotubes have been synthesized by a LPCVD on nanocrystalline Fe-Pd film. CNTs are grown for 30min and 1h respectively. From the SEM images, the diameter of these nanotubes varies from 40-80nm and the length is several micro-meter approximately. TEM observations suggest that the CNTs are multi-walled and the structure changes from ordinary geometry of CNTs to bamboo shaped. We have observed sharp G and D bands in the Raman spectra of these carbon nanotubes. Higher D-band is observed for the carbon nanotubes grown for longer time (1h), showing that these nanotubes contain more amorphous carbon. The field emission measurements for these CNTs are also performed. For CNTs grown for longer time (1h), a superior turn-on field of 4.88V/μm (when the current density achieves 10μA/cm 2 ) is obtained and a current density of 29.36mA/cm 2 can be generated at 9.59V/μm

  14. Using Ag-embedded TiO{sub 2} nanotubes array as recyclable SERS substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Yunhan, E-mail: yhling@mail.tsinghua.edu.cn [Lab of Advanced Materials, School of Materials Science & Engineering, Tsinghua University, Beijing 100084 (China); Zhuo, Yuqing; Huang, Liang [Lab of Advanced Materials, School of Materials Science & Engineering, Tsinghua University, Beijing 100084 (China); Mao, Duolu [School of Physical and Electronic Information Engineering, Qinghai Nationalities University, Xining, Qinghai 810007 (China)

    2016-12-01

    Highlights: • Ag embedded nanoparticles inside nanotube have better SERS enhancement than surface cap. • Ag NPs reconstruction via self-migration with UV and humidity control. • Self-cleaning effects both on organic molecule photo-oxidation as well as Ag ions photo-reduction. - Abstract: A simple strategy for synthesizing Ag-loaded TiO{sub 2} nanotube film for use as multifunctional photocatalyst and recyclable surface-enhanced Raman scattering (SERS) substrate is introduced. Highly aligned TiO{sub 2} nanotube arrays (TNTA) prepared via electrochemical anodization were used as a 3D rough host for silver nanoparticles. Ag deposits were sputtered in a vacuum, and it was found that their morphologies were mainly influenced by the diameters of nanotubes and the UV irradiation induced aging process, especially the self-migration of silver along the tubular wall. SERS and the self-cleaning effect were observed using Rhodamine 6G (R6G) as the probe molecule. The results showed that narrow nanotube and silver nanoparticles embedment contributed significantly to both the phenomenal SERS and recyclability.

  15. Physicochemical and bioactive properties of innovative resin-based materials containing functional halloysite-nanotubes fillers.

    Science.gov (United States)

    Degrazia, Felipe Weidenbach; Leitune, Vicente Castelo Branco; Takimi, Antonio Shigueaki; Collares, Fabrício Mezzomo; Sauro, Salvatore

    2016-09-01

    This study aimed to assess the degree of conversion, microhardness, solvent degradation, contact angle, surface free energy and bioactivity (e.g., mineral precipitation) of experimental resin-based materials containing, pure or triclosan-encapsulated, aluminosilicate-(halloysite) nanotubes. An experimental resin blend was prepared using bis-GMA/TEGDMA, 75/25wt% (control). Halloysite nanotubes (HNT) doped with or without triclosan (TCN) were first analyzed using transmission electron microscopy (TEM). HNT or HNT/TCN fillers were incorporated into the resin blend at different concentrations (5, 10, and 20wt%). Seven experimental resins were created and the degree of conversion, microhardness, solvent degradation and contact angle were assessed. Bioactive mineral precipitation induced by the experimental resins was evaluated through Raman spectroscopy and SEM-EDX. TEM showed a clear presence of TCN particles inside the tubular lumen and along the outer surfaces of the halloysite nanotubes. The degree of conversion, surface free energy, microhardness, and mineral deposition of polymers increased with higher amount of HNTs. Conversely, the higher the amount (20wt%) of TCN-loaded HNTs the lower the microhardness of the experimental resins. The incorporation of pure or TCN-loaded aluminosilicate-(halloysite) nanotubes into resin-based materials increase the bioactivity of such experimental restorative materials and promotes mineral deposition. Therefore, innovative resin-based materials containing functional halloysite-nanotube fillers may represent a valuable alternative for therapeutic minimally invasive treatments. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  16. Electrical investigations of layer-by-layer films of carbon nanotubes

    International Nuclear Information System (INIS)

    Palumbo, M; Lee, K U; Ahn, B T; Suri, A; Coleman, K S; Zeze, D; Wood, D; Pearson, C; Petty, M C

    2006-01-01

    Single-wall carbon nanotubes (SWNTs) with anionic or cationic coatings have been prepared by exploiting the ability of certain surfactants to form a monolayer shell around the nanotube. The presence of electrically charged functional groups on the surface of the SWNT allows thin film deposition to proceed via the electrostatic layer-by-layer method. This self-assembly process was monitored using the quartz microbalance technique and Raman spectroscopy, while the morphology of the resulting thin layers was studied with atomic force microscopy. A variety of different architectures has been built up. In one arrangement, a single species of a modified SWNT (anionic or cationic) was alternated with a passive polymer to form a composite structure. A 'superlattice' architecture comprising alternating anionic and cationic modified nanotubes was also fabricated. The in-plane and out-of-plane dc conductivities of the films were measured at room temperature and contrasted with reference architectures (i.e. those containing no nanotubes). The results showed clearly that the incorporation of SWNTs into the multilayer assemblies provided electrically conductive thin films. It is suggested that the current versus voltage behaviour, particularly in the out-of-plane direction, is controlled by quantum mechanical tunnelling of carriers between the nanotubes

  17. Surfactant Assisted Stabilization of Carbon Nanotubes Synthesized by a Spray Pyrolysis Method

    Directory of Open Access Journals (Sweden)

    D. Mendoza-Cachú

    2017-01-01

    Full Text Available Surface modification of carbon nanotubes has been an interesting issue from a composites materials point of view. A nanotubes agglomeration has to be avoided to achieve a homogeneous dispersion in a composite matrix. In this research, we report on the synthesis of carbon nanotubes using a variant of the chemical vapor deposition technique known as spray pyrolysis method. X-ray diffraction (XRD, transmission electron microscopy (TEM, and scanning electron microscopy (SEM studies showed that the synthesized products had an aligned structure with low purity degree, high content of catalyst particles, and a smaller amount of amorphous carbon. A secondary method was applied, which involves an acidic treatment that dissolves contaminant particles to enhance the purity of the nanotubes. Microstructural analysis, which includes XRD and SEM, indicates an effective reduction of impurities. Dispersion of the nanotubes was assessed using different surfactants, such as sodium dodecyl-sulfate (SDS and ethylenediaminetetraacetic acid (EDTA. Finally, Raman spectroscopy, UV-Vis, and SEM techniques confirm that better results were obtained with EDTA. For EDTA and SDS surfactants, low concentrations of 0.3 mg/mL and 0.2 mg/mL were most efficient, respectively.

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

    Science.gov (United States)

    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.

  19. Extending a Hybrid Tag-Based Recommender System with Personalization

    DEFF Research Database (Denmark)

    Durao, Frederico; Dolog, Peter

    2010-01-01

    extension for a hybrid tag-based recommender system, which suggests similar Web pages based on the similarity of their tags. The semantic extension aims at discovering tag relations which are not considered in basic syntax similarity. With the goal of generating more semantically grounded recommendations......, the proposal extends a hybrid tag-based recommender system with a semantic factor, which looks for tag relations in different semantic sources. In order to evaluate the benefits acquired with the semantic extension, we have compared the new findings with results from a previous experiment involving 38 people......Tagging activity has been recently identified as a potential source of knowledge about personal interests, preferences, goals, and other attributes known from user models. Tags themselves can be therefore used for finding personalized recommendations of items. This paper proposes a semantic...

  20. Design of an 1800nm Raman amplifier

    DEFF Research Database (Denmark)

    Svane, Ask Sebastian; Rottwitt, Karsten

    2013-01-01

    We present the experimental results for a Raman amplifier that operates at 1810 nm and is pumped by a Raman fiber laser at 1680 nm. Both the pump laser and the Raman amplifier is polarization maintaining. A challenge when scaling Raman amplifiers to longer wavelengths is the increase...... in transmission loss, but also the reduction in the Raman gain coefficient as the amplifier wavelength is increased. Both polarization components of the Raman gain is characterized, initially for linearly co-polarized signal and pump, subsequently linearly polarized orthogonal signal and pump. The noise...

  1. Raman Optical Activity and Raman Spectra of Amphetamine Species

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Shim, Irene; White, Peter Cyril

    2012-01-01

    Theoretical calculations and preliminary measurements of vibrational Raman optical activity (ROA) spectra of different species of amphetamine (amphetamine and amphetamine-H+) are reported for the first time. The quantum chemical calculations were carried out as hybrid ab initio DFT-molecular orbi......Theoretical calculations and preliminary measurements of vibrational Raman optical activity (ROA) spectra of different species of amphetamine (amphetamine and amphetamine-H+) are reported for the first time. The quantum chemical calculations were carried out as hybrid ab initio DFT...... are employed for identification purposes. The DFT calculations show that the most stable conformations are those allowing for close contact between the aromatic ring and the amine hydrogen atoms. The internal rotational barrier within the same amphetamine enanti- omer has a considerable influence on the Raman...

  2. Carbon Nanotube Underwater Acoustic Thermophone

    Science.gov (United States)

    2016-09-23

    nanotubes (unless encapsulated or housed) are quite fragile and are susceptible to disintegration especially if the nanotubes are touched or moved too...The acoustic impedance (defined as the product of material density and sound speed) of the top shell 12 should match the Attorney Docket No. 300009

  3. Nanoparticle uptake and their co-localization with cell compartments - a confocal Raman microscopy study at single cell level

    International Nuclear Information System (INIS)

    Estrela-Lopis, I; Donath, E; Romero, G; Rojas, E; Moya, S E

    2011-01-01

    Confocal Raman Microscopy, a non-invasive, non-destructive and label-free technique, was employed to study the uptake and localization of nanoparticles (NPs) in the Hepatocarcinoma human cell line HepG2 at the level of single cells. Cells were exposed to carbon nanotubes (CNTs) the surface of which was engineered with polyelectrolytes and lipid layers, aluminium oxide and cerium dioxide nanoparticles. Raman spectra deconvolution was applied to obtain the spatial distributions of NPs together with lipids/proteins in cells. The colocalization of the NPs with different intracellular environments, lipid bodies, protein and DNA, was inferred. Lipid coated CNTs associated preferentially with lipid rich regions, whereas polyelectrolyte coated CNTs were excluded from lipid rich regions. Al 2 O 3 NPs were found in the cytoplasm. CeO 2 NPs were readily taken up and have been observed all over the cell. Raman z-scans proved the intracellular distribution of the respective NPs.

  4. Nanoparticle uptake and their co-localization with cell compartments - a confocal Raman microscopy study at single cell level

    Science.gov (United States)

    Estrela-Lopis, I.; Romero, G.; Rojas, E.; Moya, S. E.; Donath, E.

    2011-07-01

    Confocal Raman Microscopy, a non-invasive, non-destructive and label-free technique, was employed to study the uptake and localization of nanoparticles (NPs) in the Hepatocarcinoma human cell line HepG2 at the level of single cells. Cells were exposed to carbon nanotubes (CNTs) the surface of which was engineered with polyelectrolytes and lipid layers, aluminium oxide and cerium dioxide nanoparticles. Raman spectra deconvolution was applied to obtain the spatial distributions of NPs together with lipids/proteins in cells. The colocalization of the NPs with different intracellular environments, lipid bodies, protein and DNA, was inferred. Lipid coated CNTs associated preferentially with lipid rich regions, whereas polyelectrolyte coated CNTs were excluded from lipid rich regions. Al2O3 NPs were found in the cytoplasm. CeO2 NPs were readily taken up and have been observed all over the cell. Raman z-scans proved the intracellular distribution of the respective NPs.

  5. Raman Spectroscopy for Homeland Security Applications

    Directory of Open Access Journals (Sweden)

    Gregory Mogilevsky

    2012-01-01

    Full Text Available Raman spectroscopy is an analytical technique with vast applications in the homeland security and defense arenas. The Raman effect is defined by the inelastic interaction of the incident laser with the analyte molecule’s vibrational modes, which can be exploited to detect and identify chemicals in various environments and for the detection of hazards in the field, at checkpoints, or in a forensic laboratory with no contact with the substance. A major source of error that overwhelms the Raman signal is fluorescence caused by the background and the sample matrix. Novel methods are being developed to enhance the Raman signal’s sensitivity and to reduce the effects of fluorescence by altering how the hazard material interacts with its environment and the incident laser. Basic Raman techniques applicable to homeland security applications include conventional (off-resonance Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS, resonance Raman spectroscopy, and spatially or temporally offset Raman spectroscopy (SORS and TORS. Additional emerging Raman techniques, including remote Raman detection, Raman imaging, and Heterodyne imaging, are being developed to further enhance the Raman signal, mitigate fluorescence effects, and monitor hazards at a distance for use in homeland security and defense applications.

  6. Raman chemical imaging technology for food and agricultural applications

    Science.gov (United States)

    This paper presents Raman chemical imaging technology for inspecting food and agricultural products. The paper puts emphasis on introducing and demonstrating Raman imaging techniques for practical uses in food analysis. The main topics include Raman scattering principles, Raman spectroscopy measurem...

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  8. Carbon Nanotubes and Modern Nanoagriculture

    KAUST Repository

    Serag, Maged F.

    2015-01-27

    Since their discovery, carbon nanotubes have been prominent members of the nanomaterial family. Owing to their extraordinary physical, chemical, and mechanical properties, carbon nanotubes have been proven to be a useful tool in the field of plant science. They were frequently perceived to bring about valuable biotechnological and agricultural applications that still remain beyond experimental realization. An increasing number of studies have demonstrated the ability of carbon nanotubes to traverse different plant cell barriers. These studies, also, assessed the toxicity and environmental impacts of these nanomaterials. The knowledge provided by these studies is of practical and fundamental importance for diverse applications including intracellular labeling and imaging, genetic transformation, and for enhancing our knowledge of plant cell biology. Although different types of nanoparticles have been found to activate physiological processes in plants, carbon nanotubes received particular interest. Following addition to germination medium, carbon nanotubes enhanced root growth and elongation of some plants such as onion, cucumber and rye-grass. They, also, modulated the expression of some genes that are essential for cell division and plant development. In addition, multi-walled carbon nanotubes were evidenced to penetrate thick seed coats, stimulate germination, and to enhance growth of young tomato seedlings. Multi-walled carbon nanotubes can penetrate deeply into the root system and further distribute into the leaves and the fruits. In recent studies, carbon nanotubes were reported to be chemically entrapped into the structure of plant tracheary elements. This should activate studies in the fields of plant defense and wood engineering. Although, all of these effects on plant physiology and plant developmental biology have not been fully understood, the valuable findings promises more research activity in the near future toward complete scientific understanding of

  9. Carbon nanotubes for thermal interface materials in microelectronic packaging

    Science.gov (United States)

    Lin, Wei

    , an in situ functionalization process has for the first time been demonstrated. The in situ functionalization renders the vertically aligned carbon nanotubes a proper chemical reactivity for forming chemical bonding with other substrate materials such as gold and silicon. 2. An ultrafast microwave annealing process has been developed to reduce the defect density in vertically aligned carbon nanotubes. Raman and thermogravimetric analyses have shown a distinct defect reduction in the CNTs annealed in microwave for 3 min. Fibers spun from the as-annealed CNTs, in comparison with those from the pristine CNTs, show increases of ˜35% and ˜65%, respectively, in tensile strength (˜0.8 GPa) and modulus (˜90 GPa) during tensile testing; an ˜20% improvement in electrical conductivity (˜80000 S m-1) was also reported. The mechanism of the microwave response of CNTs was discussed. Such a microwave annealing process has been extended to the preparation of reduced graphene oxide. 3. Based on the fundamental understanding of interfacial thermal transport and surface chemistry of metals and carbon nanotubes, two major transfer/assembling processes have been developed: molecular bonding and metal bonding. Effective improvement of the interfacial thermal transport has been achieved by the interfacial bonding. 4. The thermal diffusivity of vertically aligned carbon nanotube (VACNT, multi-walled) films was measured by a laser flash technique, and shown to be ˜30 mm2 s-1 along the tube-alignment direction. The calculated thermal conductivities of the VACNT film and the individual CNTs are ˜27 and ˜540 W m-1 K-1, respectively. The technique was verified to be reliable although a proper sampling procedure is critical. A systematic parametric study of the effects of defects, buckling, tip-to-tip contacts, packing density, and tube-tube interaction on the thermal diffusivity was carried out. Defects and buckling decreased the thermal diffusivity dramatically. An increased packing

  10. Theory of Graphene Raman Scattering.

    Science.gov (United States)

    Heller, Eric J; Yang, Yuan; Kocia, Lucas; Chen, Wei; Fang, Shiang; Borunda, Mario; Kaxiras, Efthimios

    2016-02-23

    Raman scattering plays a key role in unraveling the quantum dynamics of graphene, perhaps the most promising material of recent times. It is crucial to correctly interpret the meaning of the spectra. It is therefore very surprising that the widely accepted understanding of Raman scattering, i.e., Kramers-Heisenberg-Dirac theory, has never been applied to graphene. Doing so here, a remarkable mechanism we term"transition sliding" is uncovered, explaining the uncommon brightness of overtones in graphene. Graphene's dispersive and fixed Raman bands, missing bands, defect density and laser frequency dependence of band intensities, widths of overtone bands, Stokes, anti-Stokes anomalies, and other known properties emerge simply and directly.

  11. Raman fiber distributed feedback lasers.

    Science.gov (United States)

    Westbrook, Paul S; Abedin, Kazi S; Nicholson, Jeffrey W; Kremp, Tristan; Porque, Jerome

    2011-08-01

    We demonstrate fiber distributed feedback (DFB) lasers using Raman gain in two germanosilicate fibers. Our DFB cavities were 124 mm uniform fiber Bragg gratings with a π phase shift offset from the grating center. Our pump was at 1480 nm and the DFB lasers operated on a single longitudinal mode near 1584 nm. In a commercial Raman gain fiber, the maximum output power, linewidth, and threshold were 150 mW, 7.5 MHz, and 39 W, respectively. In a commercial highly nonlinear fiber, these figures improved to 350 mW, 4 MHz, and 4.3 W, respectively. In both lasers, more than 75% of pump power was transmitted, allowing for the possibility of substantial amplification in subsequent Raman gain fiber. © 2011 Optical Society of America

  12. Plasmonic optical antenna design for performing tip-enhanced Raman spectroscopy and microscopy

    International Nuclear Information System (INIS)

    Kharintsev, S S; Fishman, A I; Salakhov, M Kh; Hoffmann, G G

    2013-01-01

    This paper highlights optical plasmonic antennas designed with dc-pulsed low-voltage electrochemical etching of a gold wire for implementing tip-enhanced Raman scattering (TERS) measurements. We demonstrate a versatile electrochemical system that allows one to engineer TERS-active metallic gold tips with diverse shapes and sizes in a highly reproducible fashion. The underlying etching mechanism at a voltage-driven meniscus around a gold wire immersed into an electrolyte is discussed in detail. We show that the developed method is suitable to produce not only the simplest geometries such as cones and spheroids, but more complex designs. Attempts have been made to design plasmonic tapered antennas with quasi-uniformly spaced nano-sized bumps on the mesoscopic zone for the extra surface plasmon-light coupling. The capability of the patterned antenna to enhance and localize optical fields is demonstrated with near-field Raman microscopy and spectroscopy of single-walled carbon nanotubes bundles. (paper)

  13. The DNA hybridization assay using single-walled carbon nanotubes as ultrasensitive, long-term optical labels

    International Nuclear Information System (INIS)

    Hwang, Eung-Soo; Cao, Chengfan; Hong, Sanghyun; Jung, Hye-Jin; Cha, Chang-Yong; Choi, Jae-Boong; Kim, Young-Jin; Baik, Seunghyun

    2006-01-01

    Single walled carbon nanotubes (SWNTs) exhibit strong Raman signals as well as fluorescence emissions in the near infrared region. Such signals do not blink or photobleach under prolonged excitation, which is an advantage in optical nano-biomarker applications. In this paper, we present single-stranded DNA conjugated SWNT probes to locate a particular sequence of DNA within a complex genome. Chromosomal DNAs of human fibroblasts and Escherichia coli are used as a target and a control, respectively. Southern blotting, which uses photostable Raman signals of nanotubes instead of fluorescent dyes, demonstrates excellent sensitivity and specificity of the probes. The results show that SWNTs may be used as generic nano-biomarkers for the precise detection of specific kinds of genes

  14. A self-propagation high-temperature synthesis and annealing route to synthesis of wave-like boron nitride nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jilin; Zhang, Laiping [School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, Hubei, 430073 (China); Gu, Yunle, E-mail: ncm@mail.wit.edu.cn [School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, Hubei, 430073 (China); Pan, Xinye; Zhao, Guowei; Zhang, Zhanhui [School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, Hubei, 430073 (China)

    2013-03-15

    Highlights: ► Large quantities of wave-like BN nanotubes were synthesized by SHS-annealing method. ► The catalytic boron-containing porous precursor was produced by self-propagation high-temperature synthesis method. ► Three growth models were proposed to explain the growth mechanism of the wave-like BN nanotubes. - Abstract: Large quantities of boron nitride (BN) nanotubes were synthesized by annealing a catalytic boron-containing porous precursor in flowing NH{sub 3} gas at 1180 °C. The porous precursor was prepared by self-propagation high-temperature synthesis (SHS) method at 800 °C using Mg, B{sub 2}O{sub 3} and amorphous boron powder (α-B) as the starting materials. The porous precursor played an important role in large quantities synthesis of BN nanotubes. The as-synthesized product was characterized by X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), Raman, Scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), Transmission electron microscopy (TEM) and High-resolution transmission electron microscopy (HRTEM). Characterization results indicated that the BN nanotubes displayed wave-like inner structures with diameters in the range of 50–300 nm and average lengths of more than 10 μm. The possible growth mechanism of the BN nanotubes was also discussed.

  15. An efficient method for the carboxylation of few-wall carbon nanotubes with little damage to their sidewalls

    Energy Technology Data Exchange (ETDEWEB)

    Martín, Olga [Department of Materials Science and Engineering and Chemical Engineering, Universidad Carlos III de Madrid, Av. Universidad 30, 28911 Leganés-Madrid (Spain); Gutierrez, Humberto R. [Department of Physics and Astronomy, 102 Natural Science Building, University of Louisville, Louisville, KY 40292 (United States); Maroto-Valiente, Angel [Departamento de Química Inorgánica y Química Técnica, Facultad de Ciencias, UNED, C/ Senda del Rey 9, 28040 Madrid (Spain); Terrones, Mauricio [Research Center for Exotic Nanocarbons (JST), Shinshu University, Wakasato 4-17-1, Nagano 380-8553 (Japan); Department of Physics, Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, 104 Davey Lab., University Park, PA 16802-6300 (United States); Blanco, Tamara [Materials and Processes Department, Airbus Operations S.L., Paseo John Lennon s/n, 28906 Getafe-Madrid (Spain); Baselga, Juan, E-mail: jbaselga@ing.uc3m.es [Department of Materials Science and Engineering and Chemical Engineering, Universidad Carlos III de Madrid, Av. Universidad 30, 28911 Leganés-Madrid (Spain)

    2013-07-15

    We report a novel method that is able to efficiently functionalize carbon nanotubes (few-walled: from 1 to 6 layers and multiwalled) with a high yield of carboxyl groups, based on treatments with H{sub 2}O{sub 2} in the presence of UV light. The amount of carboxylic groups was quantified by X-ray photoelectron spectroscopy and back-titration, showing both measurements reasonable agreement. According to the zeta potential values and to the amount of suspended nanotubes, we demonstrate that the method is able to produce uniform and stable suspensions of carbon nanotubes in water. With the aid of scanning and transmission electron microscopy, thermogravimetric analysis, and Raman spectroscopy, we show that the surfaces of the tubes are not damaged by the treatment and that the functionalized tubes have an enhanced reactivity toward oxygen. This route is efficient and could now be used to fabricate polymer composites using few-walled and multiwalled carbon nanotubes. - Highlights: • We report an efficient method for acid functionalization of carbon nanotubes. • The method produces uniform and stable suspensions of carbon nanotubes in water. • The surfaces of the tubes are not damaged by the treatment.

  16. Carbon nanotubes rooted montmorillonite (CNT-MM) reinforced nanocomposite membrane for PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, Dhanagopal, E-mail: dmani_cat@yahoo.co.in [Department of Materials Engineering, Faculty of Engineering, University of Concepcion, Concepcion (Chile); Mangalaraja, Ramalinga Viswanathan, E-mail: mangal@udec.cl [Department of Materials Engineering, Faculty of Engineering, University of Concepcion, Concepcion (Chile); Avila, Ricardo E. [Personal Dosimetry Section, Chilean Nuclear Energy Commission, Cas. 188-D, Santiago (Chile); Siddheswaran, Rajendran [Department of Materials Engineering, Faculty of Engineering, University of Concepcion, Concepcion (Chile); Ananthakumar, Solaiappan [Materials and Minerals Division, National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum, Kerala (India)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Novel montmorillonite-CNT (MM-CNT) nanohybrid materials were produced by CVD. Black-Right-Pointing-Pointer Highly selective crystalline carbon nanotubes were grown over montmorillonite. Black-Right-Pointing-Pointer Fabricated Nafion-MM-CNT nanocomposite membrane by solution casting method. Black-Right-Pointing-Pointer Homogeneous dispersion of MM-CNT in the Nafion matrix was achieved. Black-Right-Pointing-Pointer Combined effect of montmorillonite and CNT improves the thermal stability of Nafion. - Abstract: Nafion based nanocomposite membranes containing montmorillonite-carbon nanotubes (a binary hybrid material) were produced to develop high performance polymer electrolyte fuel cells. Multi walled carbon nanotubes were grown over 20 and 25 wt% iron loaded montmorillonite catalysts by CVD using acetylene as the carbon precursor. Growth experiments were carried out at optimised conditions to obtain highly selective crystalline carbon nanotubes. X-ray diffraction spectra of the catalysts were recorded for the structural characterisation and definition of particle size. The carbon nanotubes obtained were examined by various physico chemical characterisation studies such as SEM, TEM, Raman spectroscopy and TG analyses to understand the morphology and crystallinity of the CNTs. The MM-CNT hybrid material with I{sub D}/I{sub G} ratio of Raman spectral band as 0.53 represents the high selectivity towards CNTs. Thus the hybrid material produced was considered as the best nanofiller to develop polymer nanocomposites. Nafion based nanocomposite membranes were prepared by adding MM-CNT as nanofiller by solution casting method. A better dispersion of MM-CNT into the Nafion matrix was observed and the addition of the MM-CNT improved the thermal stability of the Nafion membrane.

  17. Carbon nanotubes rooted montmorillonite (CNT-MM) reinforced nanocomposite membrane for PEM fuel cells

    International Nuclear Information System (INIS)

    Manikandan, Dhanagopal; Mangalaraja, Ramalinga Viswanathan; Avila, Ricardo E.; Siddheswaran, Rajendran; Ananthakumar, Solaiappan

    2012-01-01

    Highlights: ► Novel montmorillonite-CNT (MM-CNT) nanohybrid materials were produced by CVD. ► Highly selective crystalline carbon nanotubes were grown over montmorillonite. ► Fabricated Nafion-MM-CNT nanocomposite membrane by solution casting method. ► Homogeneous dispersion of MM-CNT in the Nafion matrix was achieved. ► Combined effect of montmorillonite and CNT improves the thermal stability of Nafion. - Abstract: Nafion based nanocomposite membranes containing montmorillonite-carbon nanotubes (a binary hybrid material) were produced to develop high performance polymer electrolyte fuel cells. Multi walled carbon nanotubes were grown over 20 and 25 wt% iron loaded montmorillonite catalysts by CVD using acetylene as the carbon precursor. Growth experiments were carried out at optimised conditions to obtain highly selective crystalline carbon nanotubes. X-ray diffraction spectra of the catalysts were recorded for the structural characterisation and definition of particle size. The carbon nanotubes obtained were examined by various physico chemical characterisation studies such as SEM, TEM, Raman spectroscopy and TG analyses to understand the morphology and crystallinity of the CNTs. The MM-CNT hybrid material with I D /I G ratio of Raman spectral band as 0.53 represents the high selectivity towards CNTs. Thus the hybrid material produced was considered as the best nanofiller to develop polymer nanocomposites. Nafion based nanocomposite membranes were prepared by adding MM-CNT as nanofiller by solution casting method. A better dispersion of MM-CNT into the Nafion matrix was observed and the addition of the MM-CNT improved the thermal stability of the Nafion membrane.

  18. Development of techniques for tagging precursor and essential chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Swansiger, W.A.; Shepodd, T.J. [Sandia National Labs., Livermore, CA (United States); Phillips, M.L.F. [Sandia National Labs., Albuquerque, NM (United States)

    1994-01-01

    The ability to identify the manufacturers and distributors of chemicals seized in raids of illicit drug labs would be of great value in controlling the diversion of these chemicals. We developed a tagging scheme based on the addition of sub-ppM concentrations of various combinations of rare-earth elements to the target chemicals and evaluated a number of techniques for detecting the tags. We developed soluble tags for tagging liquids and selected Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) as the preferred detection technique. We developed insoluble tags for tagging solids and developed methods to analyze them and mix them into solid precursors. We have successfully demonstrated the tagging of several solvents and two of the precursor chemicals used in one of the most popular clandestine methamphetamine syntheses (ephedrine reacting with hydriodic acid/red phosphorus). The tagging scheme is capable of yielding tens of thousands of signatures (using holmium as an internal standard and up to 9 rare-earths at up to 3 concentrations yields 3{sup 9} {minus} 1 = 19,682 signatures) and is applicable to most of the chemicals on the precursor and essential chemicals list. In the concentrations employed, the tags are safe enough to be added to pharmaceuticals and cheap enough to tag tanker loads of chemicals.

  19. Higher order mode optical fiber Raman amplifiers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Friis, Søren Michael Mørk; Usuga Castaneda, Mario A.

    2016-01-01

    We review higher order mode Raman amplifiers and discuss recent theoretical as well as experimental results including system demonstrations.......We review higher order mode Raman amplifiers and discuss recent theoretical as well as experimental results including system demonstrations....

  20. Field Raman spectrograph for environmental analysis

    International Nuclear Information System (INIS)

    Carrabba, M.M.

    1995-01-01

    The use of Raman Spectroscopy in the screening of soils, ground water, and surface waters for pollutants is described. A probe accessory for conducting surface enhanced Raman Spectroscopy is undergoing testing for dilute chlorinated solvents

  1. Raman and Photoluminescence Spectroscopy in Mineral Identification

    Science.gov (United States)

    Kuehn, J. W.

    2014-06-01

    Raman spectroscopy is particularly useful for rapid identification of minerals and gemstones. Raman spectrometers also allow PL studies for authentication of samples and geological provenance, diamond type screening and detection of HPHT treatments.

  2. Dynamics of long ring Raman fiber laser

    Science.gov (United States)

    Sukhanov, Sergey V.; Melnikov, Leonid A.; Mazhirina, Yulia A.

    2016-04-01

    The numerical model for dynamics of long fiber ring Raman laser is proposed. The model is based on the transport equations and Courant-Isaacson-Rees numerical method. Different regimes of a long ring fiber Raman laser are investigated.

  3. Analysis of tag-position bias in MPSS technology

    Directory of Open Access Journals (Sweden)

    Rattray Magnus

    2006-04-01

    Full Text Available Abstract Background Massively Parallel Signature Sequencing (MPSS technology was recently developed as a high-throughput technology for measuring the concentration of mRNA transcripts in a sample. It has previously been observed that the position of the signature tag in a transcript (distance from 3' end can affect the measurement, but this effect has not been studied in detail. Results We quantify the effect of tag-position bias in Classic and Signature MPSS technology using published data from Arabidopsis, rice and human. We investigate the relationship between measured concentration and tag-position using nonlinear regression methods. The observed relationship is shown to be broadly consistent across different data sets. We find that there exist different and significant biases in both Classic and Signature MPSS data. For Classic MPSS data, genes with tag-position in the middle-range have highest measured abundance on average while genes with tag-position in the high-range, far from the 3' end, show a significant decrease. For Signature MPSS data, high-range tag-position genes tend to have a flatter relationship between tag-position and measured abundance. Thus, our results confirm that the Signature MPSS method fixes a substantial problem with the Classic MPSS method. For both Classic and Signature MPSS data there is a positive correlation between measured abundance and tag-position for low-range tag-position genes. Compared with the effects of mRNA length and number of exons, tag-position bias seems to be more significant in Arabadopsis. The tag-position bias is reflected both in the measured abundance of genes with a significant tag count and in the proportion of unexpressed genes identified. Conclusion Tag-position bias should be taken into consideration when measuring mRNA transcript abundance using MPSS technology, both in Classic and Signature MPSS methods.

  4. Raman Spectroscopy of Microbial Pigments

    Science.gov (United States)

    Edwards, Howell G. M.; Oren, Aharon

    2014-01-01

    Raman spectroscopy is a rapid nondestructive technique providing spectroscopic and structural information on both organic and inorganic molecular compounds. Extensive applications for the method in the characterization of pigments have been found. Due to the high sensitivity of Raman spectroscopy for the detection of chlorophylls, carotenoids, scytonemin, and a range of other pigments found in the microbial world, it is an excellent technique to monitor the presence of such pigments, both in pure cultures and in environmental samples. Miniaturized portable handheld instruments are available; these instruments can be used to detect pigments in microbiological samples of different types and origins under field conditions. PMID:24682303

  5. Challenges in higher order mode Raman amplifiers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Nielsen, Kristian; Friis, Søren Michael Mørk

    2015-01-01

    A higher order Raman amplifier model that take random mode coupling into account ispresented. Mode dependent gain and signal power fluctuations at the output of the higher order modeRaman amplifier are discussed......A higher order Raman amplifier model that take random mode coupling into account ispresented. Mode dependent gain and signal power fluctuations at the output of the higher order modeRaman amplifier are discussed...

  6. Mixture analysis with laser raman spctroscopy

    International Nuclear Information System (INIS)

    Kim, M.S.; Bark, G.M.

    1981-01-01

    Trace amount of methyl orange was determined in colored medium by resonance Raman spectrometry. Without major modification of a commercial laser Raman spectrometer, the resonance Raman active molecule could be determined satisfactorily in 10sup(-5)M range when the background fluorescence was more than 20 times stronger than the signal. Use of fluorescence quenching agent was found helpful to improve the Raman signal. Suggestions for the improvement of analytical method is presented. (Author)

  7. Neural network tagging in a toy model

    International Nuclear Information System (INIS)

    Milek, Marko; Patel, Popat

    1999-01-01

    The purpose of this study is a comparison of Artificial Neural Network approach to HEP analysis against the traditional methods. A toy model used in this analysis consists of two types of particles defined by four generic properties. A number of 'events' was created according to the model using standard Monte Carlo techniques. Several fully connected, feed forward multi layered Artificial Neural Networks were trained to tag the model events. The performance of each network was compared to the standard analysis mechanisms and significant improvement was observed

  8. HPV Vaccine Safety PSA (:30) (No Tag)

    Centers for Disease Control (CDC) Podcasts

    2014-01-15

    In this 30 second public service announcement, a mother talks about the importance of protecting 11-12 year-old boys and girls with HPV vaccination. No CDC tag at the end. (Una madre habla sobre la importancia de proteger a los niños y las niñas de 11 a 12 años con la vacuna contra el VPH.).  Created: 1/15/2014 by National Center for Immunizations and Respiratory Diseases (NCIRD).   Date Released: 1/15/2014.

  9. Single spectrometer station for neutrino-tagging

    International Nuclear Information System (INIS)

    Nedyalkov, I.P.

    1984-01-01

    A neutrino tagging station built with respect to the following scheme is proposed. A beam of muons and kaons passes through a magnetic spectrometer, where the energy of each particle is measured. There are coordinate detectors behind the spectrometer in several planes, where the direction of the trajectory of a given particle is determined. Thus, mesons enter the decay point wth the known 4-momentum. Behind the decay point the direction of μ-meson generated by the decay of parent mesons is measured. It is shown that information is sufficient for determining the kind of parent particle (pion or kaon), the energy and the direction of trajectory of the neutrino

  10. Subfemtosecond pulse generation by cascade-stimulated Raman scattering with modulated Raman excitation

    International Nuclear Information System (INIS)

    Wu Kun; Wu Jian; Zeng Heping

    2003-01-01

    Subfemtosecond (sub-fs) pulses can be generated by cascade-stimulated Raman scattering in a Raman medium with modulated Raman excitations, driven by two sufficiently intense laser beams, one of which is amplitude modulated. The nonadiabatic Raman interaction establishes a strong modulated Raman coherence, which supports compression of the generated broadband Raman sidebands to a train of sub-fs pulses regardless of whether the carrier frequencies of the driving lasers are tuned above, below or on two-photon Raman resonance. (letter to the editor)

  11. Growth of vertically aligned multiwalled carbon nanotubes forests on metal alloy Ni-Nb-N with low content of catalyst

    Science.gov (United States)

    Dubkov, S.; Trifonov, A.; Shaman, Yu; Pavlov, A.; Shulyat'ev, A.; Skorik, S.; Kirilenko, E. P.; Rygalin, B.

    2016-08-01

    This research shows the possibility of carbon nanotubes (CNTs) formation on the surface of low nickel (∼ 10 at.%) Ni-Nb-N amorphous metal alloy film by CVD method at 550 °C of the gas mixture based on acetylene. The structure of CNT were studied by transmission and scanning-electron microscopy, energy-dispersive X-ray and the Raman spectroscopy.

  12. Facile graft polystyrene onto multi-walled carbon nanotubes via in situ thermo-induced radical polymerization

    International Nuclear Information System (INIS)

    Liu Peng

    2009-01-01

    A facile procedure was developed for the grafting of polystyrene onto the surfaces of multi-walled carbon nanotubes (MWNTs) via the in situ thermo-induced bulk radical polymerization of styrene at the different polymerizing temperatures, in the presence of MWNTs without any initiator added. The grafting products were validated by the dispersibility, TEM, TGA, FT-IR, and Raman analysis. The TGA results also showed the lower polymerizing temperature was propitious to the free radical addition reactions.

  13. Raman Microscopy and Microspectroscopy of Biological Materials

    NARCIS (Netherlands)

    Sijtsema, N.M.; Otto, C.; Segers-Nolten, G.M.J.; Greve, J.; Merlin, Jean Claude; Turrell, Sylvia; Huvenne, Jean Pierre

    With a confocal Raman microspectrometer it is possible to collect Raman signal of a volume of only 1 µm3 Therefore, this technique offers the possibility to obtain information about the chemical composition of small cell structures like granules, without destroying the cell [1], This makes Raman

  14. Raman spectra of lignin model compounds

    Science.gov (United States)

    Umesh P. Agarwal; Richard S. Reiner; Ashok K. Pandey; Sally A. Ralph; Kolby C. Hirth; Rajai H. Atalla

    2005-01-01

    To fully exploit the value of Raman spectroscopy for analyzing lignins and lignin containing materials, a detailed understanding of lignins’ Raman spectra needs to be achieved. Although advances made thus far have led to significant growth in application of Raman techniques, further developments are needed to improve upon the existing knowledge. Considering that lignin...

  15. Carbon Nanotube Based Molecular Electronics

    Science.gov (United States)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1998-01-01

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

  16. Tags Help Make Libraries Del.icio.us: Social Bookmarking and Tagging Boost Participation

    Science.gov (United States)

    Rethlefsen, Melissa L.

    2007-01-01

    Traditional library web products, whether online public access catalogs, library databases, or even library web sites, have long been rigidly controlled and difficult to use. Patrons regularly prefer Google's simple interface. Now social bookmarking and tagging tools help librarians bridge the gap between the library's need to offer authoritative,…

  17. POS-Tagging for informal language (study in Indonesian tweets)

    Science.gov (United States)

    Suryawati, Endang; Munandar, Devi; Riswantini, Dianadewi; Fatchuttamam Abka, Achmad; Arisal, Andria

    2018-03-01

    This paper evaluates Part-of-Speech Tagging for the formal Indonesian language can be used for the tagging process of Indonesian tweets. In this study, we add five additional tags which reflect to social media attributes to the existing original tagset. Automatic POS tagging process is done by stratified training process with 1000, 1600, and 1800 of annotated tweets. It shows that the process can achieve up to 66.36% accuracy. The experiment with original tagset gives slightly better accuracy (67.39%) than the experiment with five additional tags, but will lose important informations which given by the five additional tagset.POS-Tagging for Informal Language (Study in Indonesian Tweets).

  18. Surface Acoustic Wave Tag-Based Coherence Multiplexing

    Science.gov (United States)

    Youngquist, Robert C. (Inventor); Malocha, Donald (Inventor); Saldanha, Nancy (Inventor)

    2016-01-01

    A surface acoustic wave (SAW)-based coherence multiplexing system includes SAW tags each including a SAW transducer, a first SAW reflector positioned a first distance from the SAW transducer and a second SAW reflector positioned a second distance from the SAW transducer. A transceiver including a wireless transmitter has a signal source providing a source signal and circuitry for transmitting interrogation pulses including a first and a second interrogation pulse toward the SAW tags, and a wireless receiver for receiving and processing response signals from the SAW tags. The receiver receives scrambled signals including a convolution of the wideband interrogation pulses with response signals from the SAW tags and includes a computing device which implements an algorithm that correlates the interrogation pulses or the source signal before transmitting against the scrambled signals to generate tag responses for each of the SAW tags.

  19. Precision Electrophile Tagging in Caenorhabditis elegans.

    Science.gov (United States)

    Long, Marcus J C; Urul, Daniel A; Chawla, Shivansh; Lin, Hong-Yu; Zhao, Yi; Haegele, Joseph A; Wang, Yiran; Aye, Yimon

    2018-01-16

    Adduction of an electrophile to privileged sensor proteins and the resulting phenotypically dominant responses are increasingly appreciated as being essential for metazoan health. Functional similarities between the biological electrophiles and electrophilic pharmacophores commonly found in covalent drugs further fortify the translational relevance of these small-molecule signals. Genetically encodable or small-molecule-based fluorescent reporters and redox proteomics have revolutionized the observation and profiling of cellular redox states and electrophile-sensor proteins, respectively. However, precision mapping between specific redox-modified targets and specific responses has only recently begun to be addressed, and systems tractable to both genetic manipulation and on-target redox signaling in vivo remain largely limited. Here we engineer transgenic Caenorhabditis elegans expressing functional HaloTagged fusion proteins and use this system to develop a generalizable light-controlled approach to tagging a prototypical electrophile-sensor protein with native electrophiles in vivo. The method circumvents issues associated with low uptake/distribution and toxicity/promiscuity. Given the validated success of C. elegans in aging studies, this optimized platform offers a new lens with which to scrutinize how on-target electrophile signaling influences redox-dependent life span regulation.

  20. Hypergraph topological quantities for tagged social networks

    Science.gov (United States)

    Zlatić, Vinko; Ghoshal, Gourab; Caldarelli, Guido

    2009-09-01

    Recent years have witnessed the emergence of a new class of social networks, which require us to move beyond previously employed representations of complex graph structures. A notable example is that of the folksonomy, an online process where users collaboratively employ tags to resources to impart structure to an otherwise undifferentiated database. In a recent paper, we proposed a mathematical model that represents these structures as tripartite hypergraphs and defined basic topological quantities of interest. In this paper, we extend our model by defining additional quantities such as edge distributions, vertex similarity and correlations as well as clustering. We then empirically measure these quantities on two real life folksonomies, the popular online photo sharing site Flickr and the bookmarking site CiteULike. We find that these systems share similar qualitative features with the majority of complex networks that have been previously studied. We propose that the quantities and methodology described here can be used as a standard tool in measuring the structure of tagged networks.

  1. Further development of NEPTUN photon tagging facility

    Energy Technology Data Exchange (ETDEWEB)

    Symochko, Dmytro; Arnould, Michaela; Aumann, Thomas; Baumann, Martin; Pietralla, Norbert; Scheit, Heiko; Semmler, Diego; Walz, Christopher [Institut fuer Kernphysik, Darmstadt Univ. (Germany)

    2016-07-01

    The low-energy photon tagging facility NEPTUN at the superconducting Darmstadt linear accelerator (SDALINAC) has been constructed with the aim to study the photoabsorption cross section of the nuclei in the energy regions of Pygmy Dipole and Giant Dipole Resonances. Recently it went through the series of commissioning runs, which proved the concept and the ability of NEPTUN to tag the discreet nuclear states. Also, based on the results of the commissioning, major upgrade was developed to optimize the setup. Upgraded tagger will be able to operate with 60 MeV electron beam and will have extended focal plane with energy bite of more than 10 MeV. After completion of upgrade it will be possible to perform total dipole response measurement in the energy region 5-35 MeV for one target using only 2-3 settings of the spectrometer. Presentation will focus on the analysis results of commissioning runs and details of the proposed upgrade plan.

  2. Structural dependence of the multi-functionalized carbon nanotubes to the substituents on the grafted diazo compounds

    Science.gov (United States)

    Amiri, Rahebeh; Rasouli, Sousan; Ghasemi, Alireza; Eghbali, Babak; Mohammadi, Soutodeh

    2014-05-01

    Systematic studies on the covalent functionalization of multi-walled carbon nanotubes were performed by a series of azo molecules with different substituents. For this investigation, 4-substituted diazonium reagents have been used in the reaction with the functionalized multi-walled carbon nanotubes. We analyzed the effect of the substituted groups on the diazo component affinity in the grafting. Also, the structural differences of the final products were evaluated by visual dispersion test, UV-Vis absorption. Fourier transforms infrared, Raman, and several complementary techniques (scanning electron microscopy, thermal gravimetric analysis, and colorimetry test). Nuclear magnetic resonance spectroscopy has been used to confirm the allylic protons attached to the surface of carbon nanotubes after functionalization.

  3. Cross-Lingual Morphological Tagging for Low-Resource Languages

    OpenAIRE

    Buys, Jan; Botha, Jan A.

    2016-01-01

    Morphologically rich languages often lack the annotated linguistic resources required to develop accurate natural language processing tools. We propose models suitable for training morphological taggers with rich tagsets for low-resource languages without using direct supervision. Our approach extends existing approaches of projecting part-of-speech tags across languages, using bitext to infer constraints on the possible tags for a given word type or token. We propose a tagging model using Ws...

  4. The tagged photon beam polarization of the jet target experiment

    International Nuclear Information System (INIS)

    Bianchi, N.; Muccifora, V.

    1989-01-01

    The applicability of the residual electron selection method to the tagging method of the jet target laboratory has been studied. With this end in view the behaviour of the polarized bremsstrahlung cross section in the range considered has been analysed, while the polarization increase by means of the RES has been evaluated. The vertical conditions of the focusing of the tagging spectrometer as a function of energy have been determined. Finally the gamma beam density and the tagging efficiency have been calculated

  5. TiO2 nanotubes supported NiW hydrodesulphurization catalysts: Characterization and activity

    International Nuclear Information System (INIS)

    Palcheva, R.; Dimitrov, L.; Tyuliev, G.; Spojakina, A.; Jiratova, K.

    2013-01-01

    Highlights: ► NiW catalysts supported on TiO 2 nanotubes, titania and alumina. ► The best results are obtained with NiW/TiO 2 nanotubes in hydrodesulfurization (HDS) of thiophene. ► Active phase is Ni-WO x S y . ► Electronic promotion of W by Ti. - Abstract: High surface area TiO 2 nanotubes (Ti-NT) synthesized by alkali hydrothermal method were used as a support for NiW hydrodesulphurization catalyst. Nickel salt of 12-tungstophosphoric acid – Ni 3/2 PW 12 O 40 was applied as oxide precursor of the active components. The catalyst was characterized by S BET , XRD, UV–vis DRS, Raman spectroscopy, XPS, TPR and HRTEM. The results obtained were compared with those for the NiW catalysts prepared over high surface area titania and alumina supports. A polytungstate phase evidenced by Raman spectroscopy was observed indicating the destruction of the initial heteropolyanion. The catalytic experiments revealed two times higher thiophene conversion on NiW catalyst supported on Ti-NT than those of catalysts supported on alumina and titania. Increased HDS activity of the NiW catalyst supported on Ti-NT could be related to a higher amount of W oxysulfide entities interacting with Ni sulfide particles as consequence of the electronic effects of the Ti-NT observed with XPS analysis.

  6. Tunable synthesis of copper nanotubes

    International Nuclear Information System (INIS)

    Kaniukov, E; Yakimchuk, D; Kozlovsky, A; Shlimas, D; Zdorovets, M; Kadyrzhanov, K

    2016-01-01

    Simple method of tunable synthesis of copper nanotubes based on template synthesis was developed. A comprehensive study of the structural, morphological and electrical characteristics of the obtained nanostructures was carried out. Characterization of structural features was made by methods of scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometry analysis. Evaluation of wall thickness is made by methods of gas permeability. Electrical conductivity of nanotubes was define in the study of their current-voltage characteristics. The possibility to control of copper nanotubes physical properties by variation of the deposition parameters was shown. (paper)

  7. Multiscale Modeling with Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, A

    2006-02-21

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

  8. Raman Spectroscopy of Ocular Tissue

    Science.gov (United States)

    Ermakov, Igor V.; Sharifzadeh, Mohsen; Gellermann, Warner

    The optically transparent nature of the human eye has motivated numerous Raman studies aimed at the non-invasive optical probing of ocular tissue components critical to healthy vision. Investigations include the qualitative and quantitative detection of tissue-specific molecular constituents, compositional changes occurring with development of ocular pathology, and the detection and tracking of ocular drugs and nutritional supplements. Motivated by a better understanding of the molecular mechanisms leading to cataract formation in the aging human lens, a great deal of work has centered on the Raman detection of proteins and water content in the lens. Several protein groups and the hydroxyl response are readily detectable. Changes of protein compositions can be studied in excised noncataractous tissue versus aged tissue preparations as well as in tissue samples with artificially induced cataracts. Most of these studies are carried out in vitro using suitable animal models and conventional Raman techniques. Tissue water content plays an important role in optimum light transmission of the outermost transparent ocular structure, the cornea. Using confocal Raman spectroscopy techniques, it has been possible to non-invasively measure the water to protein ratio as a measure of hydration status and to track drug-induced changes of the hydration levels in the rabbit cornea at various depths. The aqueous humor, normally supplying nutrients to cornea and lens, has an advantageous anterior location for Raman studies. Increasing efforts are pursued to non-invasively detect the presence of glucose and therapeutic concentrations of antibiotic drugs in this medium. In retinal tissue, Raman spectroscopy proves to be an important tool for research into the causes of macular degeneration, the leading cause of irreversible vision disorders and blindness in the elderly. It has been possible to detect the spectral features of advanced glycation and advanced lipooxydation end products in

  9. Some Fundamental Limits on SAW RFID Tag Information Capacity and Collision Resolution

    Science.gov (United States)

    Barton, Richard J.

    2013-01-01

    In this paper, we apply results from multi-user information theory to study the limits of information capacity and collision resolution for SAW RFID tags. In particular, we derive bounds on the achievable data rate per tag as a function of fundamental parameters such as tag time-bandwidth product, tag signal-to-noise ratio (SNR), and number of tags in the environment. We also discuss the implications of these bounds for tag waveform design and tag interrogation efficiency

  10. Tag cloud generation for results of multiple keywords queries

    DEFF Research Database (Denmark)

    Leginus, Martin; Dolog, Peter; Lage, Ricardo Gomes

    2013-01-01

    In this paper we study tag cloud generation for retrieved results of multiple keyword queries. It is motivated by many real world scenarios such as personalization tasks, surveillance systems and information retrieval tasks defined with multiple keywords. We adjust the state-of-the-art tag cloud...... generation techniques for multiple keywords query results. Consequently, we conduct the extensive evaluation on top of three distinct collaborative tagging systems. The graph-based methods perform significantly better for the Movielens and Bibsonomy datasets. Tag cloud generation based on maximal coverage...

  11. Ethical implications of implantable radiofrequency identification (RFID) tags in humans.

    Science.gov (United States)

    Foster, Kenneth R; Jaeger, Jan

    2008-08-01

    This article reviews the use of implantable radiofrequency identification (RFID) tags in humans, focusing on the VeriChip (VeriChip Corporation, Delray Beach, FL) and the associated VeriMed patient identification system. In addition, various nonmedical applications for implanted RFID tags in humans have been proposed. The technology offers important health and nonhealth benefits, but raises ethical concerns, including privacy and the potential for coercive implantation of RFID tags in individuals. A national discussion is needed to identify the limits of acceptable use of implantable RFID tags in humans before their use becomes widespread and it becomes too late to prevent misuse of this useful but ethically problematic technology.

  12. Tag gas burnup based on three-dimensional FTR analysis

    International Nuclear Information System (INIS)

    Kidman, R.B.

    1976-01-01

    Flux spectra from a three-dimensional diffusion theory analysis of the Fast Test Reactor (FTR) are used to predict gas tag ratio changes, as a function of exposure, for each FTR fuel and absorber subassembly plenum. These flux spectra are also used to predict Xe-125 equilibrium activities in absorber plena in order to assess the feasibility of using Xe-125 gamma rays to detect and distinguish control rod failures from fuel rod failures. Worst case tag burnup changes are used in conjunction with burnup and mass spectrometer uncertainties to establish the minimum spacing of tags which allows the tags to be unambiguously identified

  13. Inverse Raman effect: applications and detection techniques

    International Nuclear Information System (INIS)

    Hughes, L.J. Jr.

    1980-08-01

    The processes underlying the inverse Raman effect are qualitatively described by comparing it to the more familiar phenomena of conventional and stimulated Raman scattering. An experession is derived for the inverse Raman absorption coefficient, and its relationship to the stimulated Raman gain is obtained. The power requirements of the two fields are examined qualitatively and quantitatively. The assumption that the inverse Raman absorption coefficient is constant over the interaction length is examined. Advantages of the technique are discussed and a brief survey of reported studies is presented

  14. Inverse Raman effect: applications and detection techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, L.J. Jr.

    1980-08-01

    The processes underlying the inverse Raman effect are qualitatively described by comparing it to the more familiar phenomena of conventional and stimulated Raman scattering. An experession is derived for the inverse Raman absorption coefficient, and its relationship to the stimulated Raman gain is obtained. The power requirements of the two fields are examined qualitatively and quantitatively. The assumption that the inverse Raman absorption coefficient is constant over the interaction length is examined. Advantages of the technique are discussed and a brief survey of reported studies is presented.

  15. The thermal properties of controllable diameter carbon nanotubes synthesized by using AB5 alloy of micrometer magnitude as catalyst

    International Nuclear Information System (INIS)

    Zhang Haiyan; Chen Yiming; Zeng Guoxun; Huang Huiping; Xie Zhiwei; Jie Xiaohua

    2007-01-01

    We have synthesized multi-wall carbon nanotubes by catalytic chemical vapour deposition (CCVD) method using an AB 5 hydrogen storage alloy with diameter ranging from 38 to 150 μm as a catalyst. The H 2 uptake capacity of the carbon nanotubes prepared using an AB 5 alloy as a catalyst is about 4 wt.% through to the pressure of 8 MPa at room temperature. Differential thermal analysis-thermogravimetric analysis (DTA-TGA) technique has been applied to investigate the effect of the diameters of the AB 5 alloy catalyst of micrometer magnitude and the technique conditions in the CCVD process on the thermal properties of carbon nanotubes. As the catalyst diameter increases from 38 to 150 μm, the average diameter of the prepared carbon nanotubes increases and the diameter distribution also enlarges. Electron microscope, Raman spectrum and thermal analysis all indicated that the catalyst sizes affect the diameter and the thermal properties of the carbon nanotubes. When the catalyst diameter increases, the initial weight loss temperature and the differential thermal peak temperature of the carbon nanotubes increases, which shows that the lager the diameter of the carbon nanotubes is, the higher the oxidation temperature, and the better the anti-oxidizablity. However, if the diameter of the catalyst is larger than 100 μm, the anti-oxidizablity does not rise anymore but tend to be invariableness. In the CCVD preparation process, the anti-oxidizability of the carbon nanotubes increases, when raising the ratio of the hydrogen gas in the reaction gas in our experimental range (4:1, 3:1, and 2:1, respectively)

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

    Science.gov (United States)

    Fifield, Leonard S.

    Carbon nanotubes have attractive inherent properties that encourage the development of new functional materials and devices based on them. The use of single wall carbon nanotubes as electromechanical actuators takes advantage of the high mechanical strength, surface area and electrical conductivity intrinsic to these molecules. The work presented here investigates the mechanisms that have been discovered for actuation of carbon nanotube paper: electrostatic, quantum chemical charge injection, pneumatic and viscoelastic. A home-built apparatus for the measurement of actuation strain is developed and utilized in the investigation. An optical fiber switch, the first demonstrated macro-scale device based on the actuation of carbon nanotubes, is described and its performance evaluated. Also presented here is a new general process designed to modify the surface of carbon nanotubes in a non-covalent, non-destructive way. This method can be used to impart new functionalities to carbon nanotube samples for a variety of applications including sensing, solar energy conversion and chemical separation. The process described involves the achievement of large degrees of graphitic surface coverage with polycyclic aromatic hydrocarbons through the use of supercritical fluids. These molecules are bifunctional agents that anchor a desired chemical group to the aromatic surface of the carbon nanotubes without adversely disrupting the conjugated backbone that gives rise the attractive electronic and physical properties of the nanotubes. Both the nanotube functionalization work and the actuator work presented here emphasize how an understanding and control of nanoscale structure and phenomena can be of vital importance in achieving desired performance for active materials. Opportunities for new devices with improved function over current state-of-the-art can be envisioned and anticipated based on this understanding and control.

  17. Carbon nanotube based photocathodes

    International Nuclear Information System (INIS)

    Hudanski, Ludovic; Minoux, Eric; Schnell, Jean-Philippe; Xavier, Stephane; Pribat, Didier; Legagneux, Pierre; Gangloff, Laurent; Teo, Kenneth B K; Robertson, John; Milne, William I

    2008-01-01

    This paper describes a novel photocathode which is an array of vertically aligned multi-walled carbon nanotubes (MWCNTs), each MWCNT being associated with one p-i-n photodiode. Unlike conventional photocathodes, the functions of photon-electron conversion and subsequent electron emission are physically separated. Photon-electron conversion is achieved with p-i-n photodiodes and the electron emission occurs from the MWCNTs. The current modulation is highly efficient as it uses an optically controlled reconfiguration of the electric field at the MWCNT locations. Such devices are compatible with high frequency and very large bandwidth operation and could lead to their application in compact, light and efficient microwave amplifiers for satellite telecommunication. To demonstrate this new photocathode concept, we have fabricated the first carbon nanotube based photocathode using silicon p-i-n photodiodes and MWCNT bunches. Using a green laser, this photocathode delivers 0.5 mA with an internal quantum efficiency of 10% and an I ON /I OFF ratio of 30

  18. Carbon nanotube array actuators

    International Nuclear Information System (INIS)

    Geier, S; Mahrholz, T; Wierach, P; Sinapius, M

    2013-01-01

    Experimental investigations of highly vertically aligned carbon nanotubes (CNTs), also known as CNT-arrays, are the main focus of this paper. The free strain as result of an active material behavior is analyzed via a novel experimental setup. Previous test experiences of papers made of randomly oriented CNTs, also called Bucky-papers, reveal comparably low free strain. The anisotropy of aligned CNTs promises better performance. Via synthesis techniques like chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), highly aligned arrays of multi-walled carbon nanotubes (MWCNTs) are synthesized. Two different types of CNT-arrays are analyzed, morphologically first, and optically tested for their active characteristics afterwards. One type of the analyzed arrays features tube lengths of 750–2000 μm with a large variety of diameters between 20 and 50 nm and a wave-like CNT-shape. The second type features a maximum, almost uniform, length of 12 μm and a constant diameter of 50 nm. Different CNT-lengths and array types are tested due to their active behavior. As result of the presented tests, it is reported that the quality of orientation is the most decisive property for excellent active behavior. Due to their alignment, CNT-arrays feature the opportunity to clarify the actuation mechanism of architectures made of CNTs. (paper)

  19. Proposal of Carbon Nanotube Inductors

    National Research Council Canada - National Science Library

    Tsubaki, K; Nakajima, Y; Hanajiri, T; Yamaguchi, H

    2006-01-01

    The inductors made of carbon Nanotube (CNT) have been proposed. Though the fabrication of the proposed inductor is still challenging and has many problems, merits of the proposed inductor are following...

  20. Noble-Metal Chalcogenide Nanotubes

    Directory of Open Access Journals (Sweden)

    Nourdine Zibouche

    2014-10-01

    Full Text Available We explore the stability and the electronic properties of hypothetical noble-metal chalcogenide nanotubes PtS2, PtSe2, PdS2 and PdSe2 by means of density functional theory calculations. Our findings show that the strain energy decreases inverse quadratically with the tube diameter, as is typical for other nanotubes. Moreover, the strain energy is independent of the tube chirality and converges towards the same value for large diameters. The band-structure calculations show that all noble-metal chalcogenide nanotubes are indirect band gap semiconductors. The corresponding band gaps increase with the nanotube diameter rapidly approaching the respective pristine 2D monolayer limit.