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Sample records for surface carbon formation

  1. Formation and composition of adsorbates on hydrophobic carbon surfaces from aqueous laccase-maltodextrin mixture suspension

    Energy Technology Data Exchange (ETDEWEB)

    Corrales Ureña, Yendry Regina, E-mail: yendry386@hotmail.com [UNESP São Paulo State University, Av. Eng. Luiz Edmundo Carrijo Coube, 14-01, Bauru, São Paulo (Brazil); Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Wiener Strasse 12, 28359 Bremen (Germany); Lisboa-Filho, Paulo Noronha [UNESP São Paulo State University, Av. Eng. Luiz Edmundo Carrijo Coube, 14-01, Bauru, São Paulo (Brazil); Szardenings, Michael [Fraunhofer Institute for Cell Therapy and Immunology IZI, Perlickstrasse 1, 04103 Leipzig (Germany); Gätjen, Linda; Noeske, Paul-Ludwig Michael; Rischka, Klaus [Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Wiener Strasse 12, 28359 Bremen (Germany)

    2016-11-01

    Highlights: • Less than 10 nm layer formed on carbon based materials composed by laccase and maltodextrin. • Improvement of the wettability of carbon based materials. • A protein-polysaccharide biofilm layer formation at solid liquid interface. • Stable layers formed under buffer and water rinsing. - Abstract: A robust procedure for the surface bio-functionalization of carbon surfaces was developed. It consists on the modification of carbon materials in contact with an aqueous suspension of the enzyme laccase from Trametes versicolor and the lyophilization agent maltodextrin, with the pH value adjusted close to the isoelectric point of the enzyme. We report in-situ investigations applying Quartz Crystal Microbalance with Dissipation (QCM-D) for carbon-coated sensor surfaces and, moreover, ex-situ measurements with static contact angle measurements, X-ray Photoelectron Spectroscopy (XPS) and Scanning Force Microscopy (SFM) for smooth Highly Oriented Pyrolytic Graphite (HOPG) substrates, for contact times between the enzyme formulation and the carbon material surface ranging from 20 s to 24 h. QCM-D studies reveals the formation of rigid layer of biomaterial, a few nanometers thin, which shows a strongly improved wettability of the substrate surface upon contact angle measurements. Following spectroscopic characterization, these layers are composed of mixtures of laccase and maltodextrin. The formation of these adsorbates is attributed to attractive interactions between laccase, the maltodextrin-based lyophilization agent and the hydrophobic carbon surfaces; a short-term contact between the aqueous laccase mixture suspension and HOPG surfaces is shown to merely result in de-wetting patterns influencing the results of contact angle measurements. The new enzyme-based surface modification of carbon-based materials is suggested to be applicable for the improvement of not only the wettability of low energy substrate surfaces with fluid formulations like coatings

  2. Selective formation of diamond-like carbon coating by surface catalyst patterning

    DEFF Research Database (Denmark)

    Palnichenko, A.V.; Mátéfi-Tempfli, M.; Mátéfi-Tempfli, Stefan

    2004-01-01

    The selective formation of diamond-like carbon coating by surface catalyst patterning was studied. DLC films was deposited using plasma enhanced chemical vapor deposition, filtered vacuum arc deposition, laser ablation, magnetron sputtering and ion-beam lithography methods. The DLC coatings were...

  3. Influence of carboxyl group formation on ammonia adsorption of NiO-templated nanoporous carbon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Long-Yue [Department of Chemistry, Inha University, 100 Inharo, Nam-gu, Incheon 402-751 (Korea, Republic of); Park, Soo-Jin, E-mail: sjpark@inha.ac.kr [Department of Chemistry, Inha University, 100 Inharo, Nam-gu, Incheon 402-751 (Korea, Republic of)

    2012-11-15

    The scope of this work was to control the surface functional groups of nanoporous carbons (NPs) by oxidizing agents (nitric acid and hydrogen peroxide) treatments and to investigate the relation between carboxyl group and ammonia removal efficiency. The NPs were directly prepared from a cation exchange resin by the carbonization of a mixture with Ni acetate at 900 Degree-Sign C. N{sub 2}/-196 Degree-Sign C adsorption, Boehm's titrations, and X-ray photoelectron spectroscopy (XPS) analyzes were employed to confirm the physicochemical properties of NPs. The ammonia removal efficiency was confirmed by temperature programmed desorption (TPD) technique. In the result, the oxygen content of NPs increased after various treatments and the highest content of carboxyl group formation appeared at a 2:3 volume ratio of HNO{sub 3}/H{sub 2}O{sub 2}. It was also found that the oxidation treatment led to an increase in ammonia removal efficiency of NPs, mainly due to an increase of acid oxygen functional groups (such as carboxyl) on NPs surfaces. -- Graphical abstract: The nanoporous carbons were prepared from an exchange resin by the carbonization of a mixture with Ni acetate for ammonia adsorption. Highlights: Black-Right-Pointing-Pointer The carbons were prepared from an exchange resin by the carbonization of a mixture with Ni acetate. Black-Right-Pointing-Pointer The carbon surfaces were modified with HNO{sub 3}/H{sub 2}O{sub 2} solution at different volume radio. Black-Right-Pointing-Pointer The highest content of carboxyl group formation appeared at a 2:3 volume ratio of HNO{sub 3}/H{sub 2}O{sub 2}. Black-Right-Pointing-Pointer The acid oxygen functional groups (such as carboxyl) on carbon surfaces led to an increase in ammonia adsorption.

  4. Can environmental conditions trigger cyanobacterial surfaces and following carbonate formation: implication for biomineralization and biotechnology

    Science.gov (United States)

    Paulo, C.; Dittrich, M.; Zhu, T.

    2015-12-01

    In this presentation we will give an overview what kind of the factors may trigger carbonate formations at the cell surfaces under a variety of environmental conditions. As examples, we will present the results from our recent studies on formation of calcium carbonates, dolomites and bio-cements. The extracellular polymeric substances (EPS) in the Synechococcuscell envelope are recognized key players in the nucleation of carbonates in marine and freshwater environments. Yet, little is known about a nutrient contents control over the molecular composition of Synechococcus cell envelope, and consequently, biomineralization. In the first study, we investigated how a variation of the phosphorus (P) in the growth media can lead to changes in the surface reactivity of the cells and impact their ability to form carbonates. The objective of the second study is to gain insights into the spatial distribution of cyanobacterial EPS and dolomite from different sediment layers of Khor Al-Adaid sabkha (Qatar). Here, we characterized microbial mats on molecular level in respect of organic and inorganic components using in-situ 2D Raman spectroscopy and Atomic Force Microscopy (AFM) were used. Additionally, 2D chemical maps of sediment layers documented spectral characterizations of minerals and organic matter of microbial origins at high spatial resolution. Finally, we will show the results from the experiments with auto-phototrophic cyanobacteria Gloeocapsa PCC73106, which habitat on the monument surfaces, towards its application for bio-concrete, a product of microbial carbonate precipitation. We studied the biomineralization in biofilm forming Gloeocapsa PCC73106 on the concrete surface as a pre-requirement for microbial carbonate precipitation. Biomineralization on the concrete surface by live cells and killed cells were compared with that under the abiotic condition. Our experiments allow us to conclude that environmental conditions play a significant role in the control of

  5. Adsorbed Carbon Formation and Carbon Hydrogenation for CO_2 Methanation on the Ni(111) Surface: ASED-MO Study

    International Nuclear Information System (INIS)

    Choe, Sang Joon; Kang, Hae Jin; Kim, Su Jin; Park, Sung Bae; Park, Dong Ho; Huh, Do Sung

    2005-01-01

    Using the ASED-MO (Atom Superposition and Electron Delocalization-Molecular Orbital) theory, we investigated carbon formation and carbon hydrogenation for CO_2 methanation on the Ni (111) surface. For carbon formation mechanism, we calculated the following activation energies, 1.27 eV for CO_2 dissociation, 2.97 eV for the CO, 1.93 eV for 2CO dissociation, respectively. For carbon methanation mechanism, we also calculated the following activation energies, 0.72 eV for methylidyne, 0.52 eV for methylene and 0.50 eV for methane, respectively. We found that the calculated activation energy of CO dissociation is higher than that of 2CO dissociation on the clean surface and base on these results that the CO dissociation step are the ratedetermining of the process. The C-H bond lengths of CH_4 the intermediate complex are 1.21 A, 1.31 A for the C···H_(_1_), and 2.82 A for the height, with angles of 105 .deg. for H_(_1_)CH and 98 .deg. for H_(_1_)CH_(_1_)

  6. The role of original surface roughness in laser-induced periodic surface structure formation process on poly-carbonate films

    International Nuclear Information System (INIS)

    Csete, M.; Hild, S.; Plettl, A.; Ziemann, P.; Bor, Zs.; Marti, O.

    2004-01-01

    Poly-carbonate films containing different types of original surface roughness were illuminated by a polarized ArF excimer laser beam having a fluence of 4 mJ/cm 2 . Atomic force microscopy was applied to study the laser-induced periodic surface structure formation process at 0 deg. , 30 deg. and 45 deg. angles of incidence. The effect of initial surface structures on the intensity distribution was investigated in cases of: (a) grains on oriented and amorphous thick films; (b) holes on thin spin-coated films; and (c) nanoparticles arranged along micrometer long sides of hexagons below the spin-coated films. The presence of the scattering objects caused symmetry breaking, if the samples were illuminated by oblique incident 's' polarized beam. The Fourier analysis of the AFM pictures has shown the competition of structures having different periods. The characteristic of the permanent surface patterns proved that the interference of the incoming beam and the beams scattered on previously existing structures is the LIPSS generating feedback process. Ring-shaped structures having 228 nm diameter were produced

  7. Corrosion inhibition performance of imidazolium ionic liquids and their influence on surface ferrous carbonate layer formation

    Science.gov (United States)

    Yang, Dongrui

    Corrosion inhibitors as effective anti-corrosion applications were widely studied and drawn much attention in both academe and industrial area. In this work, a systematic work, including inhibitors selection, anti-corrosion property and characterization, influence on scale formation, testing system design and so on, were reported. The corrosion inhibition performance of four imidazolium ionic liquids in carbon dioxide saturated NaCl solution was investigated by using electrochemical and surface analysis technologies. The four compounds are 1-ethyl-3-methylimidazolium chloride (a), 1-butyl-3-methylimidazolium chloride (b), 1-hexyl-3-methylimidazolium chloride (c), 1-decyl-3-methylimidazolium chloride (d). Under the testing conditions, compound d showed the highest inhibition efficiency and selected as the main object of further study. As a selected representative formula, 1-decyl-3-methylimidazolium chloride was studied in detail about its corrosion inhibition performance on mild steel in carbon dioxide saturated NaCl brine at pH 3.8 and 6.8. Electrochemical and surface analysis techniques were used to characterize the specimen corrosion process during the immersion in the blank and inhibiting solutions. The precorrosion of specimen surface showed significant and different influences on the anti-corrosion property of DMICL at pH 3.8 and 6.8. The corrosion inhibition efficiency (IE) was calculated based on parameters obtained from electrochemical techniques; the achieved IE was higher than 98% at the 25th hour for the steel with a well-polished surface at pH 3.8. The fitting parameters obtained from electrochemical data helped to account for the interfacial changes. As proved in previous research, 1-decyl-3-methylimidazolium chloride could be used as good corrosion inhibitors under certain conditions. However, under other conditions, such chemicals, as well as other species in oil transporting system, could be a factor influencing the evolution of protective surface

  8. Formation of carbon nano- and micro-structures on C+1 irradiated copper surfaces

    International Nuclear Information System (INIS)

    Ahmad, Shoaib

    2013-01-01

    A series of experiments has identified mechanisms of carbon nano- and micro-structure formation at room temperature, without catalyst and in the environment of immiscible metallic surroundings. The structures include threaded nano fibres, graphitic sheets and carbon onions. Copper as substrate was used due to its immiscibility with carbon. Energetic carbon ions (C + 1 ) of 0.2–2.0 MeV irradiated Cu targets. Cu substrates, apertures and 3 mm dia TEM Cu grids were implanted with the carbon. We observed wide range of μm-size structures formed on Cu grids and along the edges of the irradiated apertures. These are shown to be threaded nano fibers (TNF) of few μm thicknesses with lengths varying from 10 to 3000 μm. Secondary electron microscopy (SEM) identifies the μm-size structures while Confocal microscopy was used to learn about the mechanisms by which C + 1 irradiated Cu provides the growth environment. Huge carbon onions of diameters ranging from hundreds of nm to μm were observed in the as-grown and annealed samples. Transformations of the nanostructures were observed under prolonged electron irradiations of SEM and TEM. A mechanism for the formation of carbon nano- and micro-structures is proposed.

  9. On the formation of protective sulphide coatings on carbon steel surfaces

    International Nuclear Information System (INIS)

    Das, C.; Venkateswaran, G.

    1987-01-01

    A chemical method for protecting carbon steel surfaces by forming pyrrhotite/pyrite coatings has been developed. The protective nature of the coatings has been studied by weight loss kinetics, scanning electron microscopy and electrochemical measurements. A comparison is drawn between the protective nature of pyrite coating with that of magnetite coating. (author)

  10. Formation of carbon nanotubes in the graphite surface by Ar ion sputtering

    International Nuclear Information System (INIS)

    Wang Zhenxia; Zhu Fuying; Wang Wenmin; Yu Guoqing; Ruan Meiling; Zhang Huiming; Zhu Jingping

    1998-01-01

    The authors have investigated structures and topography features of sputtered graphite surface using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and demonstrated that carbon nanotubes can be grown up by sputtered-atom deposition on a protrusion of topography feature

  11. Long-term release of antibiotics by carbon nanotube-coated titanium alloy surfaces diminish biofilm formation by Staphylococcus epidermidis.

    Science.gov (United States)

    Hirschfeld, Josefine; Akinoglu, Eser M; Wirtz, Dieter C; Hoerauf, Achim; Bekeredjian-Ding, Isabelle; Jepsen, Søren; Haddouti, El-Mustapha; Limmer, Andreas; Giersig, Michael

    2017-05-01

    Bacterial biofilms cause a considerable amount of prosthetic joint infections every year, resulting in morbidity and expensive revision surgery. To address this problem, surface modifications of implant materials such as carbon nanotube (CNT) coatings have been investigated in the past years. CNTs are biologically compatible and can be utilized as drug delivery systems. In this study, multi-walled carbon nanotube (MWCNT) coated TiAl6V4 titanium alloy discs were fabricated and impregnated with Rifampicin, and tested for their ability to prevent biofilm formation over a period of ten days. Agar plate-based assays were employed to assess the antimicrobial activity of these surfaces against Staphylococcus epidermidis. It was shown that vertically aligned MWCNTs were more stable against attrition on rough surfaces than on polished TiAl6V4 surfaces. Discs with coated surfaces caused a significant inhibition of biofilm formation for up to five days. Therefore, MWCNT-modified surfaces may be effective against pathogenic biofilm formation on endoprostheses. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Formation of transition metal cluster adducts on the surface of single-walled carbon nanotubes: HRTEM studies

    KAUST Repository

    Kalinina, Irina V.

    2014-01-01

    We report the formation of chromium clusters on the outer walls of single-walled carbon nanotubes (SWNTs). The clusters were obtained by reacting purified SWNTs with chromium hexacarbonyl in dibutyl ether at 100°C. The functionalized SWNTs were characterized by thermogravimetic analysis, XPS, and high-resolution TEM. The curvature of the SWNTs and the high mobility of the chromium moieties on graphitic surfaces allow the growth of the metal clusters and we propose a mechanism for their formation. © 2014 Taylor and Francis Group, LLC.

  13. In situ electrochemical-mass spectroscopic investigation of solid electrolyte interphase formation on the surface of a carbon electrode

    International Nuclear Information System (INIS)

    Gourdin, Gerald; Zheng, Dong; Smith, Patricia H.; Qu, Deyang

    2013-01-01

    The energy density of an electrochemical capacitor can be significantly improved by utilizing a lithiated negative electrode and a high surface area positive electrode. During lithiation of the negative carbon electrode, the electrolyte reacts with the electrode surface and undergoes decomposition to form a solid electrolyte interphase (SEI) layer that passivates the surface of the carbon electrode from further reactions between Li and the electrolyte. The reduction reactions that the solvent undergoes also form insoluble and gaseous by-products. In this work, those gaseous by-products generated by reductive decomposition of a carbonate-based electrolyte, 1.2 M LiPF 6 in EC/PC/DEC (3:1:4), were analyzed at different stages during the lithiation process of an amorphous carbon electrode. The stages in the generation of gaseous by-products were determined to come as a result of two, 1-electron reduction steps of the cyclic carbonate components of the electrolyte. Electrochemical impedance spectroscopy was also used to investigate the two distinct electrochemical processes and the development of the two phases of the SEI structure. This is the first time that the state of an electrochemical cell during the formation of the SEI layer has been systematically correlated with theoretical reaction mechanisms through the use of in situ electrochemical-MS and impedance spectroscopy analyses

  14. Electron spectroscopy of the interface carbon layer formation on the cleavage surfaces of the layered semiconductor In4Se3 crystals

    International Nuclear Information System (INIS)

    Galiy, P.V.; Musyanovych, A.V.; Nenchuk, T.M.

    2005-01-01

    The results of the quantitative X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) of the interface carbon layer formation on the cleavage surfaces of the layered semiconductor In 4 Se 3 crystals are presented. The carbon coating formation occurs as the result of interaction of the air and residual gases atmosphere in ultra high vacuum (UHV) Auger spectrometer chamber with atomic clean interlayer cleavage surfaces of the crystals. The kinetics and peculiarities of interfacial carbon layer formation on the cleavage surfaces of the crystals, elemental and phase composition of the interface have been studied by quantitative XPS, AES and mass-spectroscopy

  15. Formation of fouling deposits on a carbon steel surface from Colombian heavy crude oil under preheating conditions

    Science.gov (United States)

    Muñoz Pinto, D. A.; Cuervo Camargo, S. M.; Orozco Parra, M.; Laverde, D.; García Vergara, S.; Blanco Pinzon, C.

    2016-02-01

    Fouling in heat exchangers is produced by the deposition of undesired materials on metal surfaces. As fouling progresses, pressure drop and heat transfer resistance is observed and therefore the overall thermal efficiency of the equipment diminishes. Fouling is mainly caused by the deposition of suspended particles, such as those from chemical reactions, crystallization of certain salts, and some corrosion processes. In order to understand the formation of fouling deposits from Colombian heavy oil (API≈12.3) on carbon steel SA 516 Gr 70, a batch stirred tank reactor was used. The reactor was operated at a constant pressure of 340psi while varying the temperature and reaction times. To evaluate the formation of deposits on the metal surfaces, the steel samples were characterized by gravimetric analysis and Scanning Electron Microscopy (SEM). On the exposed surfaces, the results revealed an increase in the total mass derived from the deposition of salt compounds, iron oxides and alkaline metals. In general, fouling was modulated by both the temperature and the reaction time, but under the experimental conditions, the temperature seems to be the predominant variable that controls and accelerates fouling.

  16. Physics of foam formation on a solid surface in carbonated liquids

    NARCIS (Netherlands)

    Zuidberg, A.F.

    1997-01-01

    The amount and size of bubbles in a foam layer that have originated from a solid surface in a gas supersaturated solution is largely determined by the physical properties of that solid and liquid surface and the supersaturation level of the gas in the liquid. The presence of pre-existent

  17. Influence of carbon on the formation of the surface layer in the process of electroerosion alloying of steel with tungsten

    Science.gov (United States)

    Vasil'eva, E. V.; Bochkov, V. E.; Mikheev, É. A.; Lyakishev, V. A.; Afanas'eva, T. N.

    1983-10-01

    With an increase in carbon content in the steel being treated, the thickness of the alloyed layer increases and its microhardness also increases. The carbon exerts a deoxidizing action on the layer being formed and promotes a reduction in the threshold of deerosion and also additional strengthening of the layer as the result of the formation of binary η-carbides.

  18. Calcium carbonate hybrid coating promotes the formation of biomimetic hydroxyapatite on titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Marcos Antônio E.; Ruiz, Gilia C.M. [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil); Faria, Amanda N. [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil); Departamento de Bioquímica e Imunologia-Faculdade de Medicina de Ribeirão Preto Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Zancanela, Daniela C.; Pereira, Lourivaldo S.; Ciancaglini, Pietro [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil); Ramos, Ana P., E-mail: anapr@ffclrp.usp.br [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil)

    2016-05-01

    Graphical abstract: - Highlights: • CaCO{sub 3} continuous films were deposited on titanium discs using a biomimetic approach. • The coatings origin hydroxyapatite when immersed in simulated body fluid. • The wettability and the free energy of the surfaces were increased after the treatment. • The coated titanium discs are bioactive and non-toxic to osteoblasts. - Abstract: CaCO{sub 3} particles dispersed in liquid media have proven to be good inductors of hydroxyapatite (HAp) growth. However, the use of CaCO{sub 3} deposited as thin films for this propose is unknown. Here, we report the growth of CaCO{sub 3} continuous films on Langmuir–Blodgett (LB) modified titanium surfaces and its use as HAp growth inductor. The Ti surfaces were modified with two, four, and six layers of dihexadecylphosphate (DHP)-LB films containing Ca{sup 2+}, exposed to CO{sub 2} (g) for 12 h. The modified surfaces were immersed in simulated body fluid (SBF) at 37 °C for 36 h and submitted to bioactivity studies. This procedure originates bioactive coatings composed by non-stoichiometric HAp as evidenced by Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). The presence of the CaCO{sub 3} film as pre-coating diminished the time necessary to growth continuous and homogeneous HAp films using a biomimetic approach. The surface properties of the films regarding their roughness, composition, charge, wettability, and surface free energy (γ{sub s}) were accessed. The presence of HAp increased the wettability and γ{sub s} of the surfaces. The coatings are not toxic for osteoblasts as observed for cell viability assays obtained after 7 and 14 days of culture. Moreover, the CaCO{sub 3} thin films promote the recovery of the osteoblasts viability more than the Ti surfaces themselves.

  19. Calcium carbonate hybrid coating promotes the formation of biomimetic hydroxyapatite on titanium surfaces

    International Nuclear Information System (INIS)

    Cruz, Marcos Antônio E.; Ruiz, Gilia C.M.; Faria, Amanda N.; Zancanela, Daniela C.; Pereira, Lourivaldo S.; Ciancaglini, Pietro; Ramos, Ana P.

    2016-01-01

    Graphical abstract: - Highlights: • CaCO 3 continuous films were deposited on titanium discs using a biomimetic approach. • The coatings origin hydroxyapatite when immersed in simulated body fluid. • The wettability and the free energy of the surfaces were increased after the treatment. • The coated titanium discs are bioactive and non-toxic to osteoblasts. - Abstract: CaCO 3 particles dispersed in liquid media have proven to be good inductors of hydroxyapatite (HAp) growth. However, the use of CaCO 3 deposited as thin films for this propose is unknown. Here, we report the growth of CaCO 3 continuous films on Langmuir–Blodgett (LB) modified titanium surfaces and its use as HAp growth inductor. The Ti surfaces were modified with two, four, and six layers of dihexadecylphosphate (DHP)-LB films containing Ca 2+ , exposed to CO 2 (g) for 12 h. The modified surfaces were immersed in simulated body fluid (SBF) at 37 °C for 36 h and submitted to bioactivity studies. This procedure originates bioactive coatings composed by non-stoichiometric HAp as evidenced by Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). The presence of the CaCO 3 film as pre-coating diminished the time necessary to growth continuous and homogeneous HAp films using a biomimetic approach. The surface properties of the films regarding their roughness, composition, charge, wettability, and surface free energy (γ s ) were accessed. The presence of HAp increased the wettability and γ s of the surfaces. The coatings are not toxic for osteoblasts as observed for cell viability assays obtained after 7 and 14 days of culture. Moreover, the CaCO 3 thin films promote the recovery of the osteoblasts viability more than the Ti surfaces themselves.

  20. A density functional theory study on the carbon chain growth of ethanol formation on Cu-Co (111) and (211) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Bohua; Dong, Xiuqin; Yu, Yingzhe [Key Laboratory for Green Chemical Technology of Ministry of Education, R& D Center for Petrochemical Technology, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Wen, Guobin [Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Zhang, Minhua, E-mail: mhzhang@tju.edu.cn [Key Laboratory for Green Chemical Technology of Ministry of Education, R& D Center for Petrochemical Technology, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China)

    2017-08-01

    Highlights: • Calculations based on the first-principle density functional theory were carried out to study ethanol formation from syngas on Cu-Co surfaces. • The most controversial reactions in ethanol formation from syngas were researched: CO dissociation mechanism and the key reactions of carbon chain growth of ethanol formation (HCO insertion reactions (CHx + HCO → CHxCHO (x = 1–3))). • Four model surfaces (Cu-Co (111) and (211) with Cu-rich or Co-rich surfaces) were built to investigate the synergy of the Cu and Co components. • The PDOS of 4d orbitals and d-band center analysis of surface Cu and Co atoms of all surfaces were studied to reveal correlation between electronic property and catalytic performance. - Abstract: Calculations based on the first-principle density functional theory were carried out to study the most controversial reactions in ethanol formation from syngas on Cu-Co surfaces: CO dissociation mechanism and the key reactions of carbon chain growth of ethanol formation (HCO insertion reactions) on four model surfaces (Cu-Co (111) and (211) with Cu-rich or Co-rich surfaces) to investigate the synergy of the Cu and Co components since the complete reaction network of ethanol formation from syngas is a huge computational burden to calculate on four Cu-Co surface models. We investigated adsorption of important species involved in these reactions, activation barrier and reaction energy of H-assisted dissociation mechanism, directly dissociation of CO, and HCO insertion reactions (CH{sub x} + HCO → CH{sub x}CHO (x = 1–3)) on four Cu-Co surface models. It was found that reactions on Cu-rich (111) and (211) surfaces all have lower activation barrier in H-assisted dissociation and HCO insertion reactions, especially CH + HCO → CHCHO reaction. The PDOS of 4d orbitals of surface Cu and Co atoms of all surfaces were studied. Analysis of d-band center of Cu and Co atoms and the activation barrier data suggested the correlation between

  1. Formation of transition metal cluster adducts on the surface of single-walled carbon nanotubes: HRTEM studies

    KAUST Repository

    Kalinina, Irina V.; Bekyarova, Elena B.; Wang, Qingxiao; Al-Hadeethi, Yas Fadel; Zhang, Xixiang; Al-Agel, Faisel; Al-Marzouki, Fahad M.; Yaghmour, Saud Jamil; Haddon, Robert C.

    2014-01-01

    We report the formation of chromium clusters on the outer walls of single-walled carbon nanotubes (SWNTs). The clusters were obtained by reacting purified SWNTs with chromium hexacarbonyl in dibutyl ether at 100°C. The functionalized SWNTs were

  2. Self-formation of a nanonet of fluorinated carbon nanowires on the Si surface by combined etching in fluorine-containing plasma

    Science.gov (United States)

    Amirov, I. I.; Gorlachev, E. S.; Mazaletskiy, L. A.; Izyumov, M. O.; Alov, N. V.

    2018-03-01

    In this work, we report a technique of the self-formation of a nanonet of fluorinated carbon nanowires on the Si surface using a combined etching in fluorine-containing C4F8/Ar and SF6 plasmas. Using scanning electron microscopy, atomic force microscopy and x-ray photoelectron spectroscopy, we show that after the etching of Si in the C4F8/Ar plasma, a fluorinated carbon film of nanometer-scale thickness is formed on its surface and its formation accelerates at elevated temperatures. After a subsequent short-term etching in the SF6 plasma, the film is modified into a nanonet of self-formed fluorinated carbon nanowires.

  3. A density functional theory study on the carbon chain growth of ethanol formation on Cu-Co (111) and (211) surfaces

    Science.gov (United States)

    Ren, Bohua; Dong, Xiuqin; Yu, Yingzhe; Wen, Guobin; Zhang, Minhua

    2017-08-01

    Calculations based on the first-principle density functional theory were carried out to study the most controversial reactions in ethanol formation from syngas on Cu-Co surfaces: CO dissociation mechanism and the key reactions of carbon chain growth of ethanol formation (HCO insertion reactions) on four model surfaces (Cu-Co (111) and (211) with Cu-rich or Co-rich surfaces) to investigate the synergy of the Cu and Co components since the complete reaction network of ethanol formation from syngas is a huge computational burden to calculate on four Cu-Co surface models. We investigated adsorption of important species involved in these reactions, activation barrier and reaction energy of H-assisted dissociation mechanism, directly dissociation of CO, and HCO insertion reactions (CHx + HCO → CHxCHO (x = 1-3)) on four Cu-Co surface models. It was found that reactions on Cu-rich (111) and (211) surfaces all have lower activation barrier in H-assisted dissociation and HCO insertion reactions, especially CH + HCO → CHCHO reaction. The PDOS of 4d orbitals of surface Cu and Co atoms of all surfaces were studied. Analysis of d-band center of Cu and Co atoms and the activation barrier data suggested the correlation between electronic property and catalytic performance. Cu-Co bimetallic with Cu-rich surface allows Co to have higher catalytic activity through the interaction of Cu and Co atom. Then it will improve the adsorption of CO and catalytic activity of Co. Thus it is more favorable to the carbon chain growth in ethanol formation. Our study revealed the factors influencing the carbon chain growth in ethanol production and explained the internal mechanism from electronic property aspect.

  4. Self-organized carbon-rich stripe formation from competitive carbon and aluminium segregation at Fe0.85Al0.15(1 1 0) surfaces

    Science.gov (United States)

    Dai, Zongbei; Borghetti, Patrizia; Mouchaal, Younes; Chenot, Stéphane; David, Pascal; Jupille, Jacques; Cabailh, Gregory; Lazzari, Rémi

    2018-06-01

    By combining Scanning Tunnelling Microscopy, Low Energy Electron Diffraction and X-ray Photoelectron Spectroscopy, it was found that the surface of A2 random alloy Fe0.85Al0.15(1 1 0) is significantly influenced by the segregation of aluminium but also of carbon bulk impurities. Below ∼ 900 K, carbon segregates in the form of self-organized protruding stripes separated by ∼ 5 nm that run along the [ 0 0 1 ] B bulk direction and cover up to 34% of the surface. Their C 1s spectroscopic signature that is dominated by graphitic carbon peaks around 900 K. Above this temperature, the surface carbon concentration decays by redissolution in the bulk, whereas an intense aluminium segregation is observed giving rise to a hexagonal superstructure. The present findings is interpreted by a competitive segregation between the two elements.

  5. Tin oxide surfaces--8. An infrared study of the mechanism of formation of a surface isocyanate species on SnO/sub 2//0. 55 CuO during catalysis of the oxidation of carbon monoxide by nitric oxide

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, P.G.; Thornton, E.W.

    1978-01-01

    In studies carried out at 470/sup 0/K, the measurements of the isotopic shifts of the 2189/cm pseudo-antisymmetric stretching vibration for carbon-13, nitrogen-15, and oxygen-18 substitution indicated that the oxygen atom of the surface isocyanate, formed as an intermediate in the reaction of CO with NO, originated from NO, not from CO as previously believed. The mechanism proposed involves the dissociative chemisorption of CO, the formation of a fulminate by the reaction of NO with the surface carbon atom, and rapid isomerization to the isocyanate.

  6. Biofunctionalization of silicone rubber with microgroove-patterned surface and carbon-ion implantation to enhance biocompatibility and reduce capsule formation

    Directory of Open Access Journals (Sweden)

    Lei ZY

    2016-10-01

    Full Text Available Ze-yuan Lei, Ting Liu, Wei-juan Li, Xiao-hua Shi, Dong-li Fan Department of Plastic and Cosmetic Surgery, XinQiao Hospital, The Third Military Medical University, ChongQing, People’s Republic of China Purpose: Silicone rubber implants have been widely used to repair soft tissue defects and deformities. However, poor biocompatibility can elicit capsule formation, usually resulting in prosthesis contracture and displacement in long-term usage. To overcome this problem, this study investigated the properties of silicone rubber materials with or without a microgroove-patterned surface and with or without carbon (C-ion implantation. Materials and methods: Atomic force microscopy, X-ray photoelectron spectroscopy, and a water contact angle test were used to characterize surface morphology and physicochemical properties. Cytocompatibility was investigated by a cell adhesion experiment, immunofluorescence staining, a Cell Counting Kit-8 assay, and scanning electron microscopy in vitro. Histocompatibility was evaluated by studying the inflammatory response and fiber capsule formation that developed after subcutaneous implantation in rats for 7 days, 15 days, and 30 days in vivo. Results: Parallel microgrooves were found on the surfaces of patterned silicone rubber (P-SR and patterned C-ion-implanted silicone rubber (PC-SR. Irregular larger peaks and deeper valleys were present on the surface of silicone rubber implanted with C ions (C-SR. The silicone rubber surfaces with microgroove patterns had stable physical and chemical properties and exhibited moderate hydrophobicity. PC-SR exhibited moderately increased dermal fibroblast cell adhesion and growth, and its surface microstructure promoted orderly cell growth. Histocompatibility experiments on animals showed that both the anti-inflammatory and antifibrosis properties of PC-SR were slightly better than those of the other materials, and there was also a lower capsular contracture rate and less

  7. Carbon steel protection in G.S. (Girlder sulfide) plants. Iron sulfide scales formation on surfaces covered by fabrication produced films. Pt. 4

    International Nuclear Information System (INIS)

    Burkart, A.L.

    1986-04-01

    This work describes the assays aimed to passivate the steel carbon of the process pipings. This steel is marked by the ASTM A 333 G6 and is chemically similar to those of isotopic exchange towers which corrode in contact with in-water hydrogen sulfide solutions forming iron sulfide protective layers. The differences between both materials lie in the surface characteristics to be passivated. The steel of towers has an internal side covered by paint which shall be removed prior to passivation. The steel's internal side shall be covered by a film formed during the fabrication process and constituted by calcinated wastes and iron oxides (magnetite, hematite and wustite). This film interferes in the formation process of passivating layers of pyrrhotite and pyrite. The possibility to passivate the pipes in their actual state was evaluated since it would result highly laborious and expensive to eliminate the film. (Author) [es

  8. Influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for the synthesis of dimethyl carbonate

    Science.gov (United States)

    Zhang, Guoqiang; Li, Zhong; Zheng, Huayan; Hao, Zhiqiang; Wang, Xia; Wang, Jiajun

    2016-12-01

    Activated carbon (AC) supported Cu catalysts are employed to study the influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for oxidative carbonylation of methanol to dimethyl carbonate (DMC). The AC supports are thermal treated under different temperatures in order to adjust the levels of surface oxygenated groups. The AC supports are characterized by BET, TPD-MS and XRD, and the Cu/AC catalysts are characterized by BET, XRD, TEM, XPS, AAS, CH3OH-TPD and N2O chemisorption. The results show that as the treatment temperature is below 800 °C, the BET surface area of the corresponding AC supports are nearly unchanged and close to that of the original AC (1529.6 m2/g). But as the thermal treatment temperature is elevated from 1000 to 1600 °C, the BET surface area of AC supports gradually decreases from 1407.6 to 972.2 m2/g. After loading of Cu, the BET surface area of copper catalysts is in the range of 834.4 to 1545.3 m2/g, which is slightly less than that of the respective supports. When AC is thermal treated at 400 and 600 °C, the unstable carboxylic acid and anhydrides groups are selectively removed, which has weakened the mobility and agglomeration of Cu species during the calcination process, and thus improve the Cu species dispersion over AC support. But as the treatment temperature is elevated from 600 °C to 1200 °C, the Cu species dispersion begins to decline suggesting further removal of stable surface oxygenated groups is unfavorable for Cu species dispersion. Moreover, higher thermal treatment temperature (above 1200 °C) promotes the graphitization degree of AC and leds to the decrease of Cu loading on AC support. Meanwhile, the removal of surface oxygenated groups by thermal treatment is conducive to the formation of more π-sites, and thus promote the reduction of Cu2+ to Cu+ and Cu0 as active centers. The specific surface area of (Cu+ + Cu0) is improved by thermal treatment of AC

  9. Luminescent Surface Quaternized Carbon Dots

    KAUST Repository

    Bourlinos, Athanasios B.; Zbořil, Radek; Petr, Jan; Bakandritsos, Aristides; Krysmann, Marta; Giannelis, Emmanuel P.

    2012-01-01

    Thermal oxidation of a salt precursor made from the acid base combination of tris(hydroxymethyl)aminomethane and betaine hydrochloride results in light-emitting surface quaternized carbon dots that are water-dispersible, display anion exchange properties, and exhibit uniform size/surface charge. © 2011 American Chemical Society.

  10. Luminescent Surface Quaternized Carbon Dots

    KAUST Repository

    Bourlinos, Athanasios B.

    2012-01-10

    Thermal oxidation of a salt precursor made from the acid base combination of tris(hydroxymethyl)aminomethane and betaine hydrochloride results in light-emitting surface quaternized carbon dots that are water-dispersible, display anion exchange properties, and exhibit uniform size/surface charge. © 2011 American Chemical Society.

  11. Adsorption, desorption, and film formation of quinacridone and its thermal cracking product indigo on clean and carbon-covered silicon dioxide surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Scherwitzl, Boris; Lassnig, Roman; Truger, Magdalena; Resel, Roland; Leising, Günther; Winkler, Adolf, E-mail: a.winkler@tugraz.at [Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz (Austria)

    2016-09-07

    The evaporation of quinacridone from a stainless steel Knudsen cell leads to the partial decomposition of this molecule in the cell, due to its comparably high sublimation temperature. At least one additional type of molecules, namely indigo, could be detected in the effusion flux. Thermal desorption spectroscopy and atomic force microscopy have been used to study the co-deposition of these molecules on sputter-cleaned and carbon-covered silicon dioxide surfaces. Desorption of indigo appears at temperatures of about 400 K, while quinacridone desorbs at around 510 K. For quinacridone, a desorption energy of 2.1 eV and a frequency factor for desorption of 1 × 10{sup 19} s{sup −1} were calculated, which in this magnitude is typical for large organic molecules. A fraction of the adsorbed quinacridone molecules (∼5%) decomposes during heating, nearly independent of the adsorbed amount, resulting in a surface composed of small carbon islands. The sticking coefficients of indigo and quinacridone were found to be close to unity on a carbon covered SiO{sub 2} surface but significantly smaller on a sputter-cleaned substrate. The reason for the latter can be attributed to insufficient energy dissipation for unfavorably oriented impinging molecules. However, due to adsorption via a hot-precursor state, the sticking probability is increased on the surface covered with carbon islands, which act as accommodation centers.

  12. In situ synchrotron X-ray diffraction study of surface scale formation during CO2 corrosion of carbon steel at temperatures up to 90 oC

    International Nuclear Information System (INIS)

    Ingham, B.; Ko, M.; Kear, G.; Kappen, P.; Laycock, N.; Kimpton, J.A.; Williams, D.E.

    2010-01-01

    In situ synchrotron X-ray diffraction was used to follow the formation of corrosion product scales on carbon steel in CO 2 saturated brine at temperatures from 40 to 90 o C. The corrosion process was accelerated by applying a small anodic current, and in selected tests a scale inhibitor, amino trimethylene phosphonic acid (ATMPA), was added. Siderite was identified as the major phase in the scale formed in all conditions. With increasing temperature, the scale formation rate increased, while the scale thickness and crystallite size decreased. Above 60 o C, the scale became increasingly protective. The scale thickness and crystallite size decreased with increasing ATMPA concentration.

  13. Carbon nanotube formation by laser direct writing

    International Nuclear Information System (INIS)

    Wu, Y.-T.; Su, H.-C.; Tsai, C.-M.; Liu, K.-L.; Chen, G.-D.; Huang, R.-H.; Yew, T.-R.

    2008-01-01

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

  14. Carbon formation on nickel and nickel-copper alloy catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Alstrup, I.; Soerensen, O.; Rostrup-Nielsen, J.R. [Haldor Topsoe Research Labs., Lyngby (Denmark); Tavares, M.T.; Bernardo, C.A.

    1998-05-01

    Equilibrium, kinetic and morphological studies of carbon formation in CH{sub 4} + H{sub 2}, CO, and CO + H{sub 2} gases on silica supported nickel and nickel-copper catalysts are reviewed. The equilibrium deviates in all cases from graphite equilibrium and more so in CO + CO{sub 2} than in CH{sub 4} + H{sub 2}. A kinetic model based on information from surface science results with chemisorption of CH{sub 4} and possibly also the first dehydrogenation step as rate controlling describes carbon formation on nickel catalyst in CH{sub 4} + H{sub 2} well. The kinetics of carbon formation in CO and CO + H{sub 2} gases are in agreement with CO disproportionation as rate determining step. The presence of hydrogen influences strongly the chemisorption of CO. Carbon filaments are formed when hydrogen is present in the gas while encapsulating carbon dominates in pure CO. Small amounts of Cu alloying promotes while larger amounts (Cu : Ni {>=} 0.1) inhibits carbon formation and changes the morphology of the filaments (``octopus`` carbon formation). Adsorption induced nickel segregation changes the kinetics of the alloy catalysts at high carbon activities. Modifications suggested in some very recent papers on the basis of new results are also briefly discussed. (orig.) 31 refs.

  15. Formation of carbon quantum dots and nanodiamonds in laser ablation of a carbon film

    Science.gov (United States)

    Sidorov, A. I.; Lebedev, V. F.; Kobranova, A. A.; Nashchekin, A. V.

    2018-01-01

    We have experimentally shown that nanosecond near-IR pulsed laser ablation of a thin amorphous carbon film produces carbon quantum dots with a graphite structure and nanodiamonds with a characteristic size of 20 - 500 nm on the substrate surface. The formation of these nanostructures is confirmed by electron microscopic images, luminescence spectra and Raman spectra. The mechanisms explaining the observed effects are proposed.

  16. Thermal performance enhancement of erythritol/carbon foam composites via surface modification of carbon foam

    Science.gov (United States)

    Li, Junfeng; Lu, Wu; Luo, Zhengping; Zeng, Yibing

    2017-03-01

    The thermal performance of the erythritol/carbon foam composites, including thermal diffusivity, thermal capacity, thermal conductivity and latent heat, were investigated via surface modification of carbon foam using hydrogen peroxide as oxider. It was found that the surface modification enhanced the wetting ability of carbon foam surface to the liquid erythritol of the carbon foam surface and promoted the increase of erythritol content in the erythritol/carbon foam composites. The dense interfaces were formed between erythritol and carbon foam, which is due to that the formation of oxygen functional groups C=O and C-OH on the carbon surface increased the surface polarity and reduced the interface resistance of carbon foam surface to the liquid erythritol. The latent heat of the erythritol/carbon foam composites increased from 202.0 to 217.2 J/g through surface modification of carbon foam. The thermal conductivity of the erythritol/carbon foam composite before and after surface modification further increased from 40.35 to 51.05 W/(m·K). The supercooling degree of erythritol also had a large decrease from 97 to 54 °C. Additionally, the simple and effective surface modification method of carbon foam provided an extendable way to enhance the thermal performances of the composites composed of carbon foams and PCMs.

  17. Acid-base characteristics of powdered-activated-carbon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Reed, B.E. (West Virginia Univ., Morgantown (United States)); Jensen, J.N.; Matsumoto, M.R. (State Univ. of New York, Buffalo (United States))

    Adsorption of heavy metals onto activated carbon has been described using the surface-complex-formation (SCF) model, a chemical equilibrium model. The SCF model requires a knowledge of the amphoteric nature of activated carbon prior to metal adsorption modeling. In the past, a single-diprotic-acid-site model had been employed to describe the amphoteric nature of activated-carbon surfaces. During this study, the amphoteric nature of two powdered activated carbons were investigated, and a three-monoprotic site surface model was found to be a plausible alternative. The single-diprotic-acid-site and two-monoprotic-site models did not describe the acid-base behavior of the two carbons studied adequately. The two-diprotic site was acceptable for only one of the study carbons. The acid-base behavior of activated carbon surfaces seem to be best modeled as a series of weak monoprotic acids.

  18. Covalent organic polymer functionalization of activated carbon surfaces through acyl chloride for environmental clean-up

    DEFF Research Database (Denmark)

    Mines, Paul D.; Thirion, Damien; Uthuppu, Basil

    2017-01-01

    Nanoporous networks of covalent organic polymers (COPs) are successfully grafted on the surfaces of activated carbons, through a series of surface modification techniques, including acyl chloride formation by thionyl chloride. Hybrid composites of activated carbon functionalized with COPs exhibit...

  19. Carbon nanostructure formation driven by energetic particles

    International Nuclear Information System (INIS)

    Zhu Zhiyuan; Gong Jinlong; Zhu Dezhang

    2006-01-01

    Carbon nanostructures, especially carbon nanotubes (CNTs), have been envisaged to be the building blocks of a variety of nanoscale devices and materials. The inherent nanometer-size and ability of being either metallic or semiconductive of CNTs lead to their application in nanoelectronics. Excellent mechanical characteristics of CNTs suggest their use as structural reinforcements. However, to fully exploit the potential applications, effective means of tailoring CNT properties must be developed. Irradiation of materials with energetic particles beams (ions and electrons) is a standard and important tool for modifying material properties. Irradiation makes it possible to dope the samples, to create local amorphous region or vice versa, recrystallize the lattice and even drive a phase transition. In this paper, we report our results of (1) phase transfromation from carbon nanotubes to nanocrystalline diamond driven by hydrogen plasma, (2) onion-like nanostructure from carbon nanotubes driven by ion beams of several tens keV, and (3) amorphous carbon nanowire network formation by ion beam irradiation. Structural phase transformation from multiwalled carbon nanotubes to nanocrystalline diamond by hydrogen plasma post-treatment was carried out. Ultrahigh equivalent diamond nucleation density of more than 1011 nuclei/cm 2 was obtained. The diamond formation and growth mechanisms were proposed to be the consequence of the formation of sp3 bonded amorphous carbon clusters. The hydrogen chemisorption on curved graphite network and the energy deposited on CNTs by continuous impingement of activated molecular or atomic hydrogen are responsible for the formation of amorphous carbon matrix. Diamond nucleates and grows in the way similar to that of diamond chemical vapor deposition processes on amorphous carbon films. Furthermore, single crystalline diamond nanorods of 4-8 nm in diameter and up to 200 nm in length have been successfully synthesized by hydrogen plasma post

  20. Non-alternant polycyclic aromatic hydrocarbons versus closed carbon surfaces

    NARCIS (Netherlands)

    Koper, Carola

    2003-01-01

    The investigations described in this thesis were initiated to study aspects of the chemistry of non-alternant PAH that are connected to the formation, the selective synthesis and the properties of closed carbon surfaces, i.e. fullerenes and carbon nanotubes. Fundamental processes responsible

  1. Electron Transfer Strategies Regulate Carbonate Mineral and Micropore Formation.

    Science.gov (United States)

    Zeng, Zhirui; Tice, Michael M

    2018-01-01

    Some microbial carbonates are robust biosignatures due to their distinct morphologies and compositions. However, whether carbonates induced by microbial iron reduction have such features is unknown. Iron-reducing bacteria use various strategies to transfer electrons to iron oxide minerals (e.g., membrane-bound enzymes, soluble electron shuttles, nanowires, as well as different mechanisms for moving over or attaching to mineral surfaces). This diversity has the potential to create mineral biosignatures through manipulating the microenvironments in which carbonate precipitation occurs. We used Shewanella oneidensis MR-1, Geothrix fermentans, and Geobacter metallireducens GS-15, representing three different strategies, to reduce solid ferric hydroxide in order to evaluate their influence on carbonate and micropore formation (micro-size porosity in mineral rocks). Our results indicate that electron transfer strategies determined the morphology (rhombohedral, spherical, or long-chained) of precipitated calcium-rich siderite by controlling the level of carbonate saturation and the location of carbonate formation. Remarkably, electron transfer strategies also produced distinctive cell-shaped micropores in both carbonate and hydroxide minerals, thus producing suites of features that could potentially serve as biosignatures recording information about the sizes, shapes, and physiologies of iron-reducing organisms. Key Words: Microbial iron reduction-Micropore-Electron transfer strategies-Microbial carbonate. Astrobiology 18, 28-36.

  2. Hydrophobic Calcium Carbonate for Cement Surface

    Directory of Open Access Journals (Sweden)

    Shashi B. Atla

    2017-12-01

    Full Text Available This report describes a novel way to generate a highly effective hydrophobic cement surface via a carbonation route using sodium stearate. Carbonation reaction was carried out at different temperatures to investigate the hydrophobicity and morphology of the calcium carbonate formed with this process. With increasing temperatures, the particles changed from irregular shapes to more uniform rod-like structures and then aggregated to form a plate-like formation. The contact angle against water was found to increase with increasing temperature; after 90 °C there was no further increase. The maximum contact angle of 129° was obtained at the temperature of 60 °C. It was also found that carbonation increased the micro hardness of the cement material. The micro hardness was found to be dependent on the morphology of the CaCO3 particles. The rod like structures which caused increased mineral filler produced a material with enhanced strength. The 13C cross polarization magic-angle spinning NMR spectra gave plausible explanation of the interaction of organic-inorganic moieties.

  3. Aspects of studies on carbon cycle at ground surface

    International Nuclear Information System (INIS)

    Yamazawa, Hiromi; Kawai, Shintaro; Moriizumi, Jun; Iida, Takao

    2008-01-01

    Radiocarbon released from nuclear facilities into the atmosphere is readily involved in a ground surface carbon cycle, which has very large spatial and temporal variability. Most of the recent studies on the carbon cycle at the ground surface are concerned with global warming, to which the ground surface plays a crucial role as a sink and/or source of atmospheric carbon dioxide. In these studies, carbon isotopes are used as tracers to quantitatively evaluate behavior of carbon. From a view point of environmental safety of nuclear facilities, radiocarbon released from a facility should be traced in a specific spatial and temporal situation because carbon cycle is driven by biological activities which are spatially and temporally heterogeneous. With this background, this paper discusses aspects of carbon cycle studies by exemplifying an experimental study on carbon cycle in a forest and a numerical study on soil organic carbon formation. The first example is a typical global warming-related observational study in which radiocarbon is used as a tracer to illustrate how carbon behaves in diurnal to seasonal time scales. The second example is on behavior of bomb carbon incorporated in soil organic matter in a long-term period of decades. The discussion will cover conceptual modelling of carbon cycle from different aspects and importance of specifying time scales of interest. (author)

  4. Electron Transfer Strategies Regulate Carbonate Mineral and Micropore Formation

    Science.gov (United States)

    Zeng, Zhirui; Tice, Michael M.

    2018-01-01

    Some microbial carbonates are robust biosignatures due to their distinct morphologies and compositions. However, whether carbonates induced by microbial iron reduction have such features is unknown. Iron-reducing bacteria use various strategies to transfer electrons to iron oxide minerals (e.g., membrane-bound enzymes, soluble electron shuttles, nanowires, as well as different mechanisms for moving over or attaching to mineral surfaces). This diversity has the potential to create mineral biosignatures through manipulating the microenvironments in which carbonate precipitation occurs. We used Shewanella oneidensis MR-1, Geothrix fermentans, and Geobacter metallireducens GS-15, representing three different strategies, to reduce solid ferric hydroxide in order to evaluate their influence on carbonate and micropore formation (micro-size porosity in mineral rocks). Our results indicate that electron transfer strategies determined the morphology (rhombohedral, spherical, or long-chained) of precipitated calcium-rich siderite by controlling the level of carbonate saturation and the location of carbonate formation. Remarkably, electron transfer strategies also produced distinctive cell-shaped micropores in both carbonate and hydroxide minerals, thus producing suites of features that could potentially serve as biosignatures recording information about the sizes, shapes, and physiologies of iron-reducing organisms.

  5. Biofilm formation on abiotic surfaces

    DEFF Research Database (Denmark)

    Tang, Lone

    2011-01-01

    Bacteria can attach to any surface in contact with water and proliferate into complex communities enclosed in an adhesive matrix, these communities are called biofilms. The matrix makes the biofilm difficult to remove by physical means, and bacteria in biofilm can survive treatment with many...

  6. Dilute Surfactant Methods for Carbonate Formations

    Energy Technology Data Exchange (ETDEWEB)

    Kishore K. Mohanty

    2006-02-01

    There are many fractured carbonate reservoirs in US (and the world) with light oil. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). The process of using dilute anionic surfactants in alkaline solutions has been investigated in this work for oil recovery from fractured oil-wet carbonate reservoirs both experimentally and numerically. This process is a surfactant-aided gravity drainage where surfactant diffuses into the matrix, lowers IFT and contact angle, which decrease capillary pressure and increase oil relative permeability enabling gravity to drain the oil up. Anionic surfactants have been identified which at dilute concentration of 0.05 wt% and optimal salinity can lower the interfacial tension and change the wettability of the calcite surface to intermediate/water-wet condition as well or better than the cationic surfactant DTAB with a West Texas crude oil. The force of adhesion in AFM of oil-wet regions changes after anionic surfactant treatment to values similar to those of water-wet regions. The AFM topography images showed that the oil-wetting material was removed from the surface by the anionic surfactant treatment. Adsorption studies indicate that the extent of adsorption for anionic surfactants on calcite minerals decreases with increase in pH and with decrease in salinity. Surfactant adsorption can be minimized in the presence of Na{sub 2}CO{sub 3}. Laboratory-scale surfactant brine imbibition experiments give high oil recovery (20-42% OOIP in 50 days; up to 60% in 200 days) for initially oil-wet cores through wettability alteration and IFT reduction. Small (<10%) initial gas saturation does not affect significantly the rate of oil recovery in the imbibition process, but larger gas saturation decreases the oil recovery rate. As the core permeability decreases, the rate of oil recovery reduces

  7. Nanophase Carbonates on Mars: Implications for Carbonate Formation and Habitability

    Science.gov (United States)

    Archer, P. Douglas, Jr.; Lauer, H. Vern; Ming, Douglas W.; Niles, Paul B.; Morris, Richard V.; Rampe, Elizabeth B.; Sutter, Brad

    2014-01-01

    reacting these materials for a number of hours, thermal analysis demonstrated the formations of carbonates that decomposed at temperatures as low as 500 degC [7]. Further work is underway to carry out the weathering process under more Mars-like conditions (low pressure and low temperature) to determine if the carbonate decomposition temperature can be shifted to even lower temperatures, consistent with what has been detected by thermal analysis instruments on Mars.

  8. Covalent attachment of pyridine-type molecules to glassy carbon surfaces by electrochemical reduction of in situ generated diazonium salts. Formation of ruthenium complexes on ligand-modified surfaces

    International Nuclear Information System (INIS)

    Yesildag, Ali; Ekinci, Duygu

    2010-01-01

    In this study, pyridine, quinoline and phenanthroline molecules were covalently bonded to glassy carbon (GC) electrode surfaces for the first time using the diazonium modification method. Then, the complexation ability of the modified films with ruthenium metal cations was investigated. The derivatization of GC surfaces with heteroaromatic molecules was achieved by electrochemical reduction of the corresponding in situ generated diazonium salts. X-ray photoelectron spectroscopy (XPS) was used to confirm the attachment of heteroaromatic molecules to the GC surfaces and to determine the surface concentration of the films. The barrier properties of the modified GC electrodes were studied in the presence of redox probes such as Fe(CN) 6 3- and Ru(NH 3 ) 6 3+ by cyclic voltammetry. Additionally, the presence of the resulting organometallic films on the surfaces was verified by XPS after the chemical transformation of the characterized ligand films to the ruthenium complex films. The electrochemical behavior of these films in acetonitrile solution was investigated using voltammetric methods, and the surface coverage of the organometallic films was determined from the reversible metal-based Ru(II)/Ru(III) oxidation waves.

  9. Covalent attachment of pyridine-type molecules to glassy carbon surfaces by electrochemical reduction of in situ generated diazonium salts. Formation of ruthenium complexes on ligand-modified surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Yesildag, Ali [Department of Chemistry, Faculty of Sciences, Atatuerk University, 25240 Erzurum (Turkey); Ekinci, Duygu, E-mail: dekin@atauni.edu.t [Department of Chemistry, Faculty of Sciences, Atatuerk University, 25240 Erzurum (Turkey)

    2010-09-30

    In this study, pyridine, quinoline and phenanthroline molecules were covalently bonded to glassy carbon (GC) electrode surfaces for the first time using the diazonium modification method. Then, the complexation ability of the modified films with ruthenium metal cations was investigated. The derivatization of GC surfaces with heteroaromatic molecules was achieved by electrochemical reduction of the corresponding in situ generated diazonium salts. X-ray photoelectron spectroscopy (XPS) was used to confirm the attachment of heteroaromatic molecules to the GC surfaces and to determine the surface concentration of the films. The barrier properties of the modified GC electrodes were studied in the presence of redox probes such as Fe(CN){sub 6}{sup 3-} and Ru(NH{sub 3}){sub 6}{sup 3+} by cyclic voltammetry. Additionally, the presence of the resulting organometallic films on the surfaces was verified by XPS after the chemical transformation of the characterized ligand films to the ruthenium complex films. The electrochemical behavior of these films in acetonitrile solution was investigated using voltammetric methods, and the surface coverage of the organometallic films was determined from the reversible metal-based Ru(II)/Ru(III) oxidation waves.

  10. Silver-Palladium Surfaces Inhibit Biofilm Formation

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Schroll, Casper; Hilbert, Lisbeth Rischel

    2009-01-01

    Undesired biofilm formation is a major concern in many areas. In the present study, we investigated biofilm-inhibiting properties of a silver-palladium surface that kills bacteria by generating microelectric fields and electrochemical redox processes. For evaluation of the biofilm inhibition...... efficacy and study of the biofilm inhibition mechanism, the silver-sensitive Escherichia coli J53 and the silver-resistant E. coli J53[pMG101] strains were used as model organisms, and batch and flow chamber setups were used as model systems. In the case of the silver-sensitive strain, the silver......-palladium surfaces killed the bacteria and prevented biofilm formation under conditions of low or high bacterial load. In the case of the silver-resistant strain, the silver-palladium surfaces killed surface-associated bacteria and prevented biofilm formation under conditions of low bacterial load, whereas under...

  11. Capacitance and surface of carbons in supercapacitors

    OpenAIRE

    Lobato Ortega, Belén; Suárez Fernández, Loreto; Guardia, Laura; Álvarez Centeno, Teresa

    2017-01-01

    This research is focused in the missing link between the specific surface area of carbons surface and their electrochemical capacitance. Current protocols used for the characterization of carbons applied in supercapacitors electrodes induce inconsistencies in the values of the interfacial capacitance (in F m−2), which is hindering the optimization of supercapacitors. The constraints of both the physisorption of N2 at 77 K and the standard methods used for the isotherm analysis frequently lead...

  12. Carbon Formation and Metal Dusting in Hot-Gas Cleanup Systems of Coal Gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, Peter F.; Judkins, Roddie R.; DeVan, Jackson H.; Wright, Ian G.

    1995-12-31

    There are several possible materials/systems degradation modes that result from gasification environments with appreciable carbon activities. These processes, which are not necessarily mutually exclusive, include carbon deposition, carburization, metal dusting, and CO disintegration of refractories. Carbon formation on solid surfaces occurs by deposition from gases in which the carbon activity (a sub C) exceeds unity. The presence of a carbon layer CO can directly affect gasifier performance by restricting gas flow, particularly in the hot gas filter, creating debris (that may be deposited elsewhere in the system or that may cause erosive damage of downstream components), and/or changing the catalytic activity of surfaces.

  13. Characterization of electron beam evaporated carbon films and compound formation on titanium and silicon

    International Nuclear Information System (INIS)

    Luthin, J.; Linsmeier, C.

    2001-01-01

    The formation of carbon-based mixed materials is unavoidable on the plasma-facing components (e.g. first wall and divertor) of fusion devices when carbon is used together with other materials. On the surfaces of these components very different conditions with respect to particle and energy impact occur. To predict the mixed material formation under these conditions the precise knowledge of the fundamental mechanisms governing these interactions is essential. In this paper we present the results of carbon interaction with titanium and silicon, as model substances for metallic and covalent carbides, during thermal treatment. To perform basic studies of the reactions of carbon with different elements, thin carbon films are produced by electron beam evaporation on the different substrates under UHV conditions. All measurements for chemical analysis are performed using X-ray photoelectron spectroscopy (XPS). We discuss first the properties of the deposited carbon films. The carbon films are characterized on inert gold surfaces and are compared to bulk graphite. Annealing of the carbon films up to 970 K leads to a transition from a disordered carbon network into a graphitic structure. Preparation of carbon films at room temperature on titanium or silicon leads to a limited carbide formation at the carbon/substrate interface. Carbon deposited in excess of several monolayers is present in elementary form. Annealing of the samples leads to complete carbidization consuming the available carbon in both cases. Titanium reacts to TiC and additional substoichiometric carbide, silicon forms SiC with exact stoichiometry. (orig.)

  14. Formation of hollow atoms above a surface

    Science.gov (United States)

    Briand, Jean Pierre; Phaneuf, Ronald; Terracol, Stephane; Xie, Zuqi

    2012-06-01

    Slow highly stripped ions approaching or penetrating surfaces are known to capture electrons into outer shells of the ions, leaving the innermost shells empty, and forming hollow atoms. Electron capture occurs above and below the surfaces. The existence of hollow atoms below surfaces e.g. Ar atoms whose K and L shells are empty, with all electrons lying in the M and N shells, was demonstrated in 1990 [1]. At nm above surfaces, the excited ions may not have enough time to decay before hitting the surfaces, and the formation of hollow atoms above surfaces has even been questioned [2]. To observe it, one must increase the time above the surface by decelerating the ions. We have for the first time decelerated O^7+ ions to energies as low as 1 eV/q, below the minimum energy gained by the ions due to the acceleration by their image charge. As expected, no ion backscattering (trampoline effect) above dielectric (Ge) was observed and at the lowest ion kinetic energies, most of the observed x-rays were found to be emitted by the ions after surface contact. [4pt] [1] J. P. Briand et al., Phys.Rev.Lett. 65(1990)159.[0pt] [2] J.P. Briand, AIP Conference Proceedings 215 (1990) 513.

  15. Formation of graphene on Ru(0001) surface

    Institute of Scientific and Technical Information of China (English)

    Pan Yi; Shi Dong-Xia; Gao Hong-Jun

    2007-01-01

    We report on the formation of a graphene monolayer on a Ru(0001) surface by annealing the Ru(0001) crystal.The samples are characterized by scanning tunnelling microscopy (STM) and Auger electron spectroscopy (AES). STM images show that the Moiré pattern is caused by the graphene layer mismatched with the underlying Ru(0001) surface and has an N × N superlattice. It is further found that the graphene monolayer on a Ru(0001) surface is very stable at high temperatures. Our results provide a simple and convenient method to produce a graphene monolayer on the Ru(0001) surface, which is used as a template for fabricating functional nanostructures needed in future nano devices and catalysis.

  16. Formation of carbon nanostructures using acetylene, argon-acetylene and argon-hydrogen-acetylene plasmas

    International Nuclear Information System (INIS)

    Marcinauskas, L.; Grigonis, A.; Minialga, V.; Marcinauskas, L.; Valincius, V.

    2013-01-01

    The films prepared in argon-acetylene plasma are attributed to graphite-like carbon films. Addition of the hydrogen decreases growth rate and the surface roughness of the films and lead to the formation of nanocrystalline graphite. The carbon nanotubes were formed at low (≤ 450°C; p = 40 Pa) temperature in pure acetylene plasma. (authors)

  17. Formation of carbon containing layers on tungsten test limiters

    International Nuclear Information System (INIS)

    Rubel, M.; Philipps, V.; Huber, A.; Tanabe, T.

    1999-01-01

    Tungsten test limiters of mushroom shape and a plasma facing area of approximately 100 cm 2 were exposed at the TEXTOR-94 tokamak to a number of deuterium fuelled discharges performed under various operation conditions. Two types of limiters were tested: a sole tungsten limiter and a twin limiter consisting of two halves, one made of tungsten and another of graphite. The exposed surfaces were examined with ion beam analysis methods and laser profilometry. The formation of some deposition zones was observed near the edges of the limiters. The deuterium-to-carbon concentration ratio was in the range from 0.04 to 0.11 and around 0.2 for the sole tungsten and the twin limiter, respectively. Significant amounts of the co-deposited tungsten and silicon atoms were found on the graphite part of the twin limiter indicating the formation of mixed W-C-Si compounds. (orig.)

  18. Bioactive carbon-PEEK composites prepared by chemical surface treatment.

    Science.gov (United States)

    Miyazaki, Toshiki; Matsunami, Chisato; Shirosaki, Yuki

    2017-01-01

    Polyetheretherketone (PEEK) has attracted much attention as an artificial intervertebral spacer for spinal reconstruction. Furthermore, PEEK plastic reinforced with carbon fiber has twice the bending strength of pure PEEK. However, the PEEK-based materials do not show ability for direct bone bonding, i.e., bioactivity. Although several trials have been conducted for enabling PEEK with bioactivity, few studies have reported on bioactive surface modification of carbon-PEEK composites. In the present study, we attempted the preparation of bioactive carbon-PEEK composites by chemical treatments with H 2 SO 4 and CaCl 2 . Bioactivity was evaluated by in vitro apatite formation in simulated body fluid (SBF). The apatite formation on the carbon-PEEK composite was compared with that of pure PEEK. Both pure PEEK and carbon-PEEK composite formed the apatite in SBF when they were treated with H 2 SO 4 and CaCl 2 ; the latter showed higher apatite-forming ability than the former. It is conjectured that many functional groups able to induce the apatite nucleation, such as sulfo and carboxyl groups, are incorporated into the dispersed carbon phase in the carbon-PEEK composites. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Formate stability and carbonate hydrogenation on strained Cu overlayers on Pt(111)

    DEFF Research Database (Denmark)

    Schumacher, Nana Maria Pii; Andersson, Klas Jerker; Nerlov, Jesper

    2008-01-01

    Formate (HCOO) synthesis, decomposition and the hydrogenation of carbonate (CO3) on Cu overlayers deposited on a Pt(111) single crystal are investigated to examine the reactivity of a Cu surface under tensile strain with defects present. Formate is synthesized from a 0.5 bar mixture of 70% CO2...

  20. Surface protection of austenitic steels by carbon nanotube coatings

    Science.gov (United States)

    MacLucas, T.; Schütz, S.; Suarez, S.; Mücklich, F.

    2018-03-01

    In the present study, surface protection properties of multiwall carbon nanotubes (CNTs) deposited on polished austenitic stainless steel are evaluated. Electrophoretic deposition is used as a coating technique. Contact angle measurements reveal hydrophilic as well as hydrophobic wetting characteristics of the carbon nanotube coating depending on the additive used for the deposition. Tribological properties of carbon nanotube coatings on steel substrate are determined with a ball-on-disc tribometer. Effective lubrication can be achieved by adding magnesium nitrate as an additive due to the formation of a holding layer detaining CNTs in the contact area. Furthermore, wear track analysis reveals minimal wear on the coated substrate as well as carbon residues providing lubrication. Energy dispersive x-ray spectroscopy is used to qualitatively analyse the elemental composition of the coating and the underlying substrate. The results explain the observed wetting characteristics of each coating. Finally, merely minimal oxidation is detected on the CNT-coated substrate as opposed to the uncoated sample.

  1. Surface modification of commercial tin coatings by carbon ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, L J; Sood, D K; Manory, R R [Royal Melbourne Inst. of Tech., VIC (Australia)

    1994-12-31

    Commercial TiN coatings of about 2 {mu}m thickness on high speed steel substrates were implanted at room temperature with 95 keV carbon ions at nominal doses between 1 x 10{sup 17} - 8x10{sup 17} ions cm{sup -2}. Carbon ion implantation induced a significant improvement in ultramicrohardness, friction coefficient and wear properties. The surface microhardness increases monotonically by up to 115% until a critical dose is reached. Beyond this dose the hardness decreases, but remains higher than that of unimplanted sample. A lower friction coefficient and a longer transition period towards a steady state condition were obtained by carbon ion implantation. The changes in tribomechanical properties are discussed in terms of radiation damage and possible formation of a second phase rich in carbon. 6 refs., 3 figs.

  2. Surface modification of commercial tin coatings by carbon ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, L.J.; Sood, D.K.; Manory, R.R. [Royal Melbourne Inst. of Tech., VIC (Australia)

    1993-12-31

    Commercial TiN coatings of about 2 {mu}m thickness on high speed steel substrates were implanted at room temperature with 95 keV carbon ions at nominal doses between 1 x 10{sup 17} - 8x10{sup 17} ions cm{sup -2}. Carbon ion implantation induced a significant improvement in ultramicrohardness, friction coefficient and wear properties. The surface microhardness increases monotonically by up to 115% until a critical dose is reached. Beyond this dose the hardness decreases, but remains higher than that of unimplanted sample. A lower friction coefficient and a longer transition period towards a steady state condition were obtained by carbon ion implantation. The changes in tribomechanical properties are discussed in terms of radiation damage and possible formation of a second phase rich in carbon. 6 refs., 3 figs.

  3. Surface modification of commercial tin coatings by carbon ion implantation

    International Nuclear Information System (INIS)

    Liu, L.J.; Sood, D.K.; Manory, R.R.

    1993-01-01

    Commercial TiN coatings of about 2 μm thickness on high speed steel substrates were implanted at room temperature with 95 keV carbon ions at nominal doses between 1 x 10 17 - 8x10 17 ions cm -2 . Carbon ion implantation induced a significant improvement in ultramicrohardness, friction coefficient and wear properties. The surface microhardness increases monotonically by up to 115% until a critical dose is reached. Beyond this dose the hardness decreases, but remains higher than that of unimplanted sample. A lower friction coefficient and a longer transition period towards a steady state condition were obtained by carbon ion implantation. The changes in tribomechanical properties are discussed in terms of radiation damage and possible formation of a second phase rich in carbon. 6 refs., 3 figs

  4. High-surface-area active carbon

    International Nuclear Information System (INIS)

    O'Grady, T.M.; Wennerberg, A.N.

    1986-01-01

    This paper describes the preparation and properties of a unique active carbon having exceptionally high surface areas, over 2500 m 2 /gm, and extraordinary adsorptive capacities. The carbon is made by a direct chemical activation route in which petroleum coke or other carbonaceous sources are reacted with excess potassium hydroxide at 400 0 to 500 0 C to an intermediate product that is subsequently pyrolyzed at 800 0 to 900 0 C to active carbon containing potassium salts. These are removed by water washing and the carbon is dried to produce a powdered product. A granular carbon can also be made by further processing the powdered carbon by using specialized granulation techniques. Typical properties of the carbon include Iodine Numbers of 3000 to 3600, methylene blue adsorption of 650 to 750 mg/gm, pore volumes of 2.0 to 2.6 cc/gm and less than 3.0% ash. This carbon's high adsorption capacities make it uniquely suited for numerous demanding applications in the medical area, purifications, removal of toxic substances, as catalyst carriers, etc

  5. The effect of carbon chain length of starting materials on the formation of carbon dots and their optical properties

    Science.gov (United States)

    Pan, Xiaohua; Zhang, Yan; Sun, Xiaobo; Pan, Wei; Yu, Guifeng; Si, Shuxin; Wang, Jinping

    2018-04-01

    Carbon dots (CDs) have attracted increasing attention due to their high performances and potential applications in wide range of areas. However, their emission mechanism is not clear so far. In order to reveal more factors contributing to the emission of CDs, the effect of carbon chain length of starting materials on the formation of CDs and their optical properties was experimentally investigated in this work. In order to focus on the effect of carbon chain length, the starting materials with C, O, N in fully identical forms and only carbon chain lengths being different were selected for synthesizing CDs, including citric acid (CA) and adipic acid (AA) as carbon sources, and diamines with different carbon chain lengths (H2N(CH2)nNH2, n = 2, 4, 6) as nitrogen sources, as well as ethylenediamine (EDA) as nitrogen source and diacids with different carbon chain lengths (HOOC(CH2)nCOOH, n = 0, 2, 4, 6) as carbon sources. Therefore, the effect of carbon chain length of starting materials on the formation and optical properties of CDs can be systematically investigated by characterizing and comparing the structures and optical properties of as-prepared nine types of CDs. Moreover, the density of –NH2 on the surface of the CDs was quantitatively detected by a spectrophotometry so as to elucidate the relationship between the –NH2 related surface state and the optical properties.

  6. Carbon deposition on nickel ferrites and nickel-magnetite surfaces

    International Nuclear Information System (INIS)

    Allen, G.C.; Jutson, J.A.

    1988-06-01

    Carbon deposition on Commercial Advanced Gas-Cooled Reactor (CAGR) fuel cladding and heat exchanger surfaces lowers heat transfer efficiency and increases fuel pin temperatures. Several types of deposit have been identified including both thin dense layers and also low density columnar deposits with filamentary or convoluted laminar structure. The low-density types are often associated with particles containing iron, nickel or manganese. To identify the role of nickel in the deposition process surfaces composed of nickel-iron spinels or metallic nickel/magnetite mixtures have been exposed to γ radiation in a gas environment simulating that in the reactor. Examination of these surfaces by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) have shown that while metallic nickel (Ni(O)) catalyses the formation of filamentary low density carbon deposits, the presence of divalent nickel (Ni(II)) sites in spinel type oxides is associated only with dense deposits. (author)

  7. Photo-induced surface functionalization of carbon surfaces: The role of photoelectron ejection

    International Nuclear Information System (INIS)

    Colavita, Paula E.; Sun Bin; Tse, K.-Y.; Hamers, Robert J.

    2008-01-01

    Carbon-based materials are attractive for a wide range of applications, from biomaterials to fuel cells; however, their effective use often requires controlling the surface chemistry to incorporate recognition moieties or reactive centers. The high stability of carbon also makes it a challenging material to functionalize; recently, the use of ultraviolet light (254 nm) to initiate functionalization of carbon surfaces has emerged as a way to obtain carbon/organic interfaces with tailored properties. The authors have investigated the mechanism of covalent grafting of amorphous carbon surfaces with functional organic molecules using the photochemical reaction of terminal alkenes. Measurements comparing the reactivity of different n-alkenes bearing different terminal groups at the terminus opposite the olefin showed pronounced differences in reactivity. They characterized the rate and final coverage of the resulting organic layers using x-ray photoelectron spectroscopy and infrared reflection-absorption spectroscopy. Ultraviolet photoelectron spectroscopy and photocurrent measurements suggested that the reaction involves photoelectron emission from the carbon surface into the liquid phase. Density functional calculations show a strong correlation between the electron affinity of the alkenes and the observed reactivity. The specific terminal group opposite to the olefin was found to play an important role in the stabilization of excess negative charges on the molecule, thus explaining the strong dependence of reactivity on the particular terminal group. These findings suggest that the reaction involves injection of photoelectrons into the alkene acceptor levels, leading to the formation of radical anions in the liquid phase. Finally, the authors demonstrate that the grafting of marginally reactive alkenes can be enhanced by seeding the surface with a small amount of good electron accepting groups. These results provide fundamental new insights into the role of

  8. The effect of carbon monoxide on planetary haze formation

    Energy Technology Data Exchange (ETDEWEB)

    Hörst, S. M.; Tolbert, M. A, E-mail: sarah.horst@colorado.edu [Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO (United States)

    2014-01-20

    Organic haze plays a key role in many planetary processes ranging from influencing the radiation budget of an atmosphere to serving as a source of prebiotic molecules on the surface. Numerous experiments have investigated the aerosols produced by exposing mixtures of N{sub 2}/CH{sub 4} to a variety of energy sources. However, many N{sub 2}/CH{sub 4} atmospheres in both our solar system and extrasolar planetary systems also contain carbon monoxide (CO). We have conducted a series of atmosphere simulation experiments to investigate the effect of CO on the formation and particle size of planetary haze analogues for a range of CO mixing ratios using two different energy sources, spark discharge and UV. We find that CO strongly affects both number density and particle size of the aerosols produced in our experiments and indicates that CO may play an important, previously unexplored, role in aerosol chemistry in planetary atmospheres.

  9. Tribological behavior and film formation mechanisms of carbon nanopearls

    Science.gov (United States)

    Hunter, Chad Nicholas

    amounts of undesired carbon (99.36 atomic % carbon as measured by XPS) because carbon rather than gold was sputtered from the magnetron target surface. Carbon impurities of co-deposited films were reduced with increasing oxygen concentration using argon-oxygen mixtures; EQP analysis showed that reactive oxygen species such as O and O+ effectively remove unwanted carbon during co-deposition processes. The tribological behavior of films deposited using simultaneous MAPLE and magnetron sputtering was similar to hydrogenated Diamond-like Carbon (DLC) in that a structure transformation (graphitization) occurred in the wear track during cyclic loading resulting in low friction coefficients. In fact, carbon and hydrocarbon fragments from solvent vapor were incorporated into the films leading to formation of hydrogenated DLC-gold composites. This behavior occurs for frozen toluene MAPLE targets regardless of whether they are loaded with CNPs. The exception to this is in a humid air environment where higher friction coefficients are observed for CNP-loaded targets. In these studies, the potential of carbon nanopearls to create environmentally stable solid lubricants has been demonstrated for future aerospace needs. This development could drastically change current approaches of lubrication for space applications. Additionally a new MAPLE-sputtering process in which solvent-dispersed nano-scale materials are incorporated into metal and ceramic matrices was developed to enable synthesis of novel nanostructured hybrid materials for a variety of applications.

  10. Liquid surface model for carbon nanotube energetics

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Mathew, Maneesh; Solov'yov, Andrey V.

    2008-01-01

    an important insight in the energetics and stability of nanotubes of different chirality and might be important for the understanding of nanotube growth process. For the computations we use empirical Brenner and Tersoff potentials and discuss their applicability to the study of carbon nanotubes. From......In the present paper we developed a model for calculating the energy of single-wall carbon nanotubes of arbitrary chirality. This model, which we call as the liquid surface model, predicts the energy of a nanotube with relative error less than 1% once its chirality and the total number of atoms...... the calculated energies we determine the elastic properties of the single-wall carbon nanotubes (Young modulus, curvature constant) and perform a comparison with available experimental measurements and earlier theoretical predictions....

  11. Latest Permian carbonate carbon isotope variability traces heterogeneous organic carbon accumulation and authigenic carbonate formation

    Science.gov (United States)

    Schobben, Martin; van de Velde, Sebastiaan; Gliwa, Jana; Leda, Lucyna; Korn, Dieter; Struck, Ulrich; Vinzenz Ullmann, Clemens; Hairapetian, Vachik; Ghaderi, Abbas; Korte, Christoph; Newton, Robert J.; Poulton, Simon W.; Wignall, Paul B.

    2017-11-01

    Bulk-carbonate carbon isotope ratios are a widely applied proxy for investigating the ancient biogeochemical carbon cycle. Temporal carbon isotope trends serve as a prime stratigraphic tool, with the inherent assumption that bulk micritic carbonate rock is a faithful geochemical recorder of the isotopic composition of seawater dissolved inorganic carbon. However, bulk-carbonate rock is also prone to incorporate diagenetic signals. The aim of the present study is to disentangle primary trends from diagenetic signals in carbon isotope records which traverse the Permian-Triassic boundary in the marine carbonate-bearing sequences of Iran and South China. By pooling newly produced and published carbon isotope data, we confirm that a global first-order trend towards depleted values exists. However, a large amount of scatter is superimposed on this geochemical record. In addition, we observe a temporal trend in the amplitude of this residual δ13C variability, which is reproducible for the two studied regions. We suggest that (sub-)sea-floor microbial communities and their control on calcite nucleation and ambient porewater dissolved inorganic carbon δ13C pose a viable mechanism to induce bulk-rock δ13C variability. Numerical model calculations highlight that early diagenetic carbonate rock stabilization and linked carbon isotope alteration can be controlled by organic matter supply and subsequent microbial remineralization. A major biotic decline among Late Permian bottom-dwelling organisms facilitated a spatial increase in heterogeneous organic carbon accumulation. Combined with low marine sulfate, this resulted in varying degrees of carbon isotope overprinting. A simulated time series suggests that a 50 % increase in the spatial scatter of organic carbon relative to the average, in addition to an imposed increase in the likelihood of sampling cements formed by microbial calcite nucleation to 1 out of 10 samples, is sufficient to induce the observed signal of carbon

  12. Latest Permian carbonate carbon isotope variability traces heterogeneous organic carbon accumulation and authigenic carbonate formation

    Directory of Open Access Journals (Sweden)

    M. Schobben

    2017-11-01

    Full Text Available Bulk-carbonate carbon isotope ratios are a widely applied proxy for investigating the ancient biogeochemical carbon cycle. Temporal carbon isotope trends serve as a prime stratigraphic tool, with the inherent assumption that bulk micritic carbonate rock is a faithful geochemical recorder of the isotopic composition of seawater dissolved inorganic carbon. However, bulk-carbonate rock is also prone to incorporate diagenetic signals. The aim of the present study is to disentangle primary trends from diagenetic signals in carbon isotope records which traverse the Permian–Triassic boundary in the marine carbonate-bearing sequences of Iran and South China. By pooling newly produced and published carbon isotope data, we confirm that a global first-order trend towards depleted values exists. However, a large amount of scatter is superimposed on this geochemical record. In addition, we observe a temporal trend in the amplitude of this residual δ13C variability, which is reproducible for the two studied regions. We suggest that (sub-sea-floor microbial communities and their control on calcite nucleation and ambient porewater dissolved inorganic carbon δ13C pose a viable mechanism to induce bulk-rock δ13C variability. Numerical model calculations highlight that early diagenetic carbonate rock stabilization and linked carbon isotope alteration can be controlled by organic matter supply and subsequent microbial remineralization. A major biotic decline among Late Permian bottom-dwelling organisms facilitated a spatial increase in heterogeneous organic carbon accumulation. Combined with low marine sulfate, this resulted in varying degrees of carbon isotope overprinting. A simulated time series suggests that a 50 % increase in the spatial scatter of organic carbon relative to the average, in addition to an imposed increase in the likelihood of sampling cements formed by microbial calcite nucleation to 1 out of 10 samples, is sufficient to induce the

  13. Thermal carbonization of nanoporous silicon: Formation of carbon ...

    Indian Academy of Sciences (India)

    Raman, Fourier transform infrared spectroscopy (FTIR) and electron microscope studies, revealed that the ... the carbonization of PS, the argon gas flow rate was kept at 30 sccm. In the mean time, ... ion laser (Spectra Physics) tuned at 488 nm.

  14. Carbon dust formation in a cold plasma from cathode sputtering

    International Nuclear Information System (INIS)

    Arnas, C.; Mouberi, A.; Hassouni, K.; Michau, A.; Lombardi, G.; Bonnin, X.; Benedic, F.; Pegourie, B.

    2009-01-01

    Nanoparticles are produced in argon glow plasmas where carbon is introduced by sputtering of a graphite cathode. A scaling law of growth is reported on as a function of the discharge time. Two successive stages of growth of concomitant agglomeration and carbon deposition are observed, followed by a final stage of growth by carbon deposition. A model of formation of molecular precursors by coagulation of neutral clusters on the one hand and of neutral-negative clusters on the other hand is presented, based on formation enthalpy and cluster geometry.

  15. Carbon dust formation in a cold plasma from cathode sputtering

    Science.gov (United States)

    Arnas, C.; Mouberi, A.; Hassouni, K.; Michau, A.; Lombardi, G.; Bonnin, X.; Bénédic, F.; Pégourié, B.

    2009-06-01

    Nanoparticles are produced in argon glow plasmas where carbon is introduced by sputtering of a graphite cathode. A scaling law of growth is reported on as a function of the discharge time. Two successive stages of growth of concomitant agglomeration and carbon deposition are observed, followed by a final stage of growth by carbon deposition. A model of formation of molecular precursors by coagulation of neutral clusters on the one hand and of neutral-negative clusters on the other hand is presented, based on formation enthalpy and cluster geometry.

  16. Carbon diffusion and kinetics during the lath martensite formation

    International Nuclear Information System (INIS)

    Xu Zuyao

    1995-01-01

    Calculations verify that carbon diffusion may occur during the lath martensite formation. Accordingly, the diffusion of interstitial atoms or ions must be taken into account when martensitic transformation is defined as a diffusionless transformation. In derivation of the kinetics equation of the athermal martensitic transformation, regarding the carbon diffusion, i.e. the enrichment of the austenite during the lath martensite formation, and ΔG γ fehler being function of the temperature and the carbon content in austenite, the kinetics equation is modified to a general form as: f=1-exp[β(C1-C0)-α(Ms-Tq)] where C0 and C1 are carbon contents in the austenite before and after quenching respectively. Consequently, the alloying element not only influences Ms, but also the diffusibility of carbon and both factors govern the amount of retained austenite in quenched steel which dominates in determing the toughness of the steel. (orig.)

  17. Iron cycling at corroding carbon steel surfaces

    Science.gov (United States)

    Lee, Jason S.; McBeth, Joyce M.; Ray, Richard I.; Little, Brenda J.; Emerson, David

    2013-01-01

    Surfaces of carbon steel (CS) exposed to mixed cultures of iron-oxidizing bacteria (FeOB) and dissimilatory iron-reducing bacteria (FeRB) in seawater media under aerobic conditions were rougher than surfaces of CS exposed to pure cultures of either type of microorganism. The roughened surface, demonstrated by profilometry, is an indication of loss of metal from the surface. In the presence of CS, aerobically grown FeOB produced tight, twisted helical stalks encrusted with iron oxides. When CS was exposed anaerobically in the presence of FeRB, some surface oxides were removed. However, when the same FeOB and FeRB were grown together in an aerobic medium, FeOB stalks were less encrusted with iron oxides and appeared less tightly coiled. These observations suggest that iron oxides on the stalks were reduced and solubilized by the FeRB. Roughened surfaces of CS and denuded stalks were replicated with three culture combinations of different species of FeOB and FeRB under three experimental conditions. Measurements of electrochemical polarization resistance established different rates of corrosion of CS in aerobic and anaerobic media, but could not differentiate rate differences between sterile controls and inoculated exposures for a given bulk concentration of dissolved oxygen. Similarly, total iron in the electrolyte could not be used to differentiate treatments. The experiments demonstrate the potential for iron cycling (oxidation and reduction) on corroding CS in aerobic seawater media. PMID:24093730

  18. In Situ Formation of Carbon Nanomaterials on Bulk Metallic Materials

    Directory of Open Access Journals (Sweden)

    J. Y. Xu

    2014-01-01

    Full Text Available Carbon nanomaterials were synthesized in situ on bulk 316L stainless steel, pure cobalt, and pure nickel by hybrid surface mechanical attrition treatment (SMAT. The microstructures of the treated samples and the resulted carbon nanomaterials were investigated by SEM and TEM characterizations. Different substrates resulted in different morphologies of products. The diameter of carbon nanomaterials is related to the size of the nanograins on the surface layer of substrates. The possible growth mechanism was discussed. Effects of the main parameters of the synthesis, including the carbon source and gas reactant composition, hydrogen, and the reaction temperature, were studied. Using hybrid SMAT is proved to be an effective way to synthesize carbon nanomaterials in situ on surfaces of metallic materials.

  19. Martian Cryogenic Carbonate Formation: Stable Isotope Variations Observed in Laboratory Studies

    Science.gov (United States)

    Socki, Richard A.; Niles, Paul B.; Sun, Tao; Fu, Qi; Romanek, Christopher S.; Gibson, Everett K. Jr.

    2014-01-01

    The history of water on Mars is tied to the formation of carbonates through atmospheric CO2 and its control of the climate history of the planet. Carbonate mineral formation under modern martian atmospheric conditions could be a critical factor in controlling the martian climate in a means similar to the rock weathering cycle on Earth. The combination of evidence for liquid water on the martian surface and cold surface conditions suggest fluid freezing could be very common on the surface of Mars. Cryogenic calcite forms easily from freezing solutions when carbon dioxide degasses quickly from Ca-bicarbonate-rich water, a process that has been observed in some terrestrial settings such as arctic permafrost cave deposits, lake beds of the Dry Valleys of Antarctica, and in aufeis (river icings) from rivers of N.E. Alaska. A series of laboratory experiments were conducted that simulated cryogenic carbonate formation on Mars in order to understand their isotopic systematics. The results indicate that carbonates grown under martian conditions show variable enrichments from starting bicarbonate fluids in both carbon and oxygen isotopes beyond equilibrium values.

  20. Star formation and the surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    Phillipps, S.; Disney, M.

    1985-01-01

    The (blue) surface brightness of spiral galaxies is significantly correlated with their Hα linewidth. This can be most plausibly interpreted as a correlation of surface brightness with star formation rate. There is also a significant difference in surface brightness between galaxies forming stars in a grand design spiral pattern and those with floc star formation regions. (author)

  1. The effects of surface modification on carbon felt electrodes for use in vanadium redox flow batteries

    International Nuclear Information System (INIS)

    Kim, Ki Jae; Kim, Young-Jun; Kim, Jae-Hun; Park, Min-Sik

    2011-01-01

    Highlights: ► We observed the physical and chemical changes on the surface of carbon felts after various surface modifications. ► The surface area and chemistry of functional groups formed on the surface of carbon felt are critical to determine the kinetics of the redox reactions of vanadium ions. ► By incorporation of the surface modifications into the electrode preparation, the electrochemical activity of carbon felts could be notably enhanced. - Abstract: The surface of carbon felt electrodes has been modified for improving energy efficiency of vanadium redox flow batteries. For comparative purposes, the effects of various surface modifications such as mild oxidation, plasma treatment, and gamma-ray irradiation on the electrochemical properties of carbon felt electrodes were investigated at optimized conditions. The cell energy efficiency was improved from 68 to 75% after the mild oxidation of the carbon felt at 500 °C for 5 h. This efficiency improvement could be attributed to the increased surface area of the carbon felt electrode and the formation of functional groups on its surface as a result of the modification. On the basis of various structural and electrochemical characterizations, a relationship between the surface nature and electrochemical activity of the carbon felt electrodes is discussed.

  2. Formation of cerussite and hydrocerussite during adsorption of lead from aqueous solution on oxidized carbons by cold oxygen plasma

    Energy Technology Data Exchange (ETDEWEB)

    De Velasco Maldonado, Paola S. [Instituto Tecnologico de Aguascalientes, Av. Adolfo López Mateos No. 1801 Ote. C.P, Aguascalientes, Ags, 20256 (Mexico); Hernández-Montoya, Virginia, E-mail: virginia.hernandez@yahoo.com.mx [Instituto Tecnologico de Aguascalientes, Av. Adolfo López Mateos No. 1801 Ote. C.P, Aguascalientes, Ags, 20256 (Mexico); Concheso, A.; Montes-Morán, Miguel A. [Instituto Nacional del Carbon, INCAR-CSIC, Apartado 73, E-33080, Oviedo (Spain)

    2016-11-15

    Highlights: • The formation of cerussite and hydrocerussite was observed on the carbon surface. • Occurrence of CaCO{sub 3} on the carbons surface plays a crucial role in the formation. • The carbons were prepared by carbonization and oxidation with cold oxygen plasma. • Oxidation with cold oxygen plasma increases the formation of these compounds. - Abstract: A new procedure of elimination of Pb{sup 2+} from aqueous solution using carbon adsorbents, in which high amounts of cerussite and hydrocerussite are deposited on the carbon surfaces, is reported. The procedure includes the preparation of carbons from selected lignocellulosic wastes (pecan nut shells and peach stones) by single carbonization and further oxidation with cold oxygen plasma. The materials prior and after the oxidation treatment were characterized using elemental analysis, FT-IR spectroscopy, SEM/EDX analysis, adsorption of N{sub 2} at −196 °C and X-ray photoelectron spectroscopy. The adsorption of Pb{sup 2+} was carried out in batch systems under constant agitation. The formation of cerussite and hydrocerussite on the spent carbon surfaces was confirmed by XRD, SEM/EDX and FT-IR. A Pb{sup 2+} removal mechanism is proposed in which a co-precipitation of lead nitrate and calcium carbonate would render the formation of the lead carbonates. In such mechanism, the occurrence of CaCO{sub 3} on the surface of the adsorbents plays a crucial role. The presence of calcium carbonate on the precursors is understood on the basis of the thermal evolution of calcium oxalate originally present in the biomass. The oxygen plasma treatment helps to expose the calcium carbonate nanocrystals thus improving dramatically the removal capacity of Pb{sup 2+}. Accordingly, retention capacities as high as 63 mg of Pb{sup 2+} per gram of adsorbent have been attained.

  3. Formation of cerussite and hydrocerussite during adsorption of lead from aqueous solution on oxidized carbons by cold oxygen plasma

    International Nuclear Information System (INIS)

    De Velasco Maldonado, Paola S.; Hernández-Montoya, Virginia; Concheso, A.; Montes-Morán, Miguel A.

    2016-01-01

    Highlights: • The formation of cerussite and hydrocerussite was observed on the carbon surface. • Occurrence of CaCO_3 on the carbons surface plays a crucial role in the formation. • The carbons were prepared by carbonization and oxidation with cold oxygen plasma. • Oxidation with cold oxygen plasma increases the formation of these compounds. - Abstract: A new procedure of elimination of Pb"2"+ from aqueous solution using carbon adsorbents, in which high amounts of cerussite and hydrocerussite are deposited on the carbon surfaces, is reported. The procedure includes the preparation of carbons from selected lignocellulosic wastes (pecan nut shells and peach stones) by single carbonization and further oxidation with cold oxygen plasma. The materials prior and after the oxidation treatment were characterized using elemental analysis, FT-IR spectroscopy, SEM/EDX analysis, adsorption of N_2 at −196 °C and X-ray photoelectron spectroscopy. The adsorption of Pb"2"+ was carried out in batch systems under constant agitation. The formation of cerussite and hydrocerussite on the spent carbon surfaces was confirmed by XRD, SEM/EDX and FT-IR. A Pb"2"+ removal mechanism is proposed in which a co-precipitation of lead nitrate and calcium carbonate would render the formation of the lead carbonates. In such mechanism, the occurrence of CaCO_3 on the surface of the adsorbents plays a crucial role. The presence of calcium carbonate on the precursors is understood on the basis of the thermal evolution of calcium oxalate originally present in the biomass. The oxygen plasma treatment helps to expose the calcium carbonate nanocrystals thus improving dramatically the removal capacity of Pb"2"+. Accordingly, retention capacities as high as 63 mg of Pb"2"+ per gram of adsorbent have been attained.

  4. Effect of carbonic anhydrase on silicate weathering and carbonate formation at present day CO₂ concentrations compared to primordial values.

    Science.gov (United States)

    Xiao, Leilei; Lian, Bin; Hao, Jianchao; Liu, Congqiang; Wang, Shijie

    2015-01-13

    It is widely recognized that carbonic anhydrase (CA) participates in silicate weathering and carbonate formation. Nevertheless, it is still not known if the magnitude of the effect produced by CA on surface rock evolution changes or not. In this work, CA gene expression from Bacillus mucilaginosus and the effects of recombination protein on wollastonite dissolution and carbonate formation under different conditions are explored. Real-time fluorescent quantitative PCR was used to explore the correlation between CA gene expression and sufficiency or deficiency in calcium and CO₂ concentration. The results show that the expression of CA genes is negatively correlated with both CO₂ concentration and ease of obtaining soluble calcium. A pure form of the protein of interest (CA) is obtained by cloning, heterologous expression, and purification. The results from tests of the recombination protein on wollastonite dissolution and carbonate formation at different levels of CO₂ concentration show that the magnitudes of the effects of CA and CO₂ concentration are negatively correlated. These results suggest that the effects of microbial CA in relation to silicate weathering and carbonate formation may have increased importance at the modern atmospheric CO₂ concentration compared to 3 billion years ago.

  5. Effect of carbonic anhydrase on silicate weathering and carbonate formation at present day CO2 concentrations compared to primordial values

    Science.gov (United States)

    Xiao, Leilei; Lian, Bin; Hao, Jianchao; Liu, Congqiang; Wang, Shijie

    2015-01-01

    It is widely recognized that carbonic anhydrase (CA) participates in silicate weathering and carbonate formation. Nevertheless, it is still not known if the magnitude of the effect produced by CA on surface rock evolution changes or not. In this work, CA gene expression from Bacillus mucilaginosus and the effects of recombination protein on wollastonite dissolution and carbonate formation under different conditions are explored. Real-time fluorescent quantitative PCR was used to explore the correlation between CA gene expression and sufficiency or deficiency in calcium and CO2 concentration. The results show that the expression of CA genes is negatively correlated with both CO2 concentration and ease of obtaining soluble calcium. A pure form of the protein of interest (CA) is obtained by cloning, heterologous expression, and purification. The results from tests of the recombination protein on wollastonite dissolution and carbonate formation at different levels of CO2 concentration show that the magnitudes of the effects of CA and CO2 concentration are negatively correlated. These results suggest that the effects of microbial CA in relation to silicate weathering and carbonate formation may have increased importance at the modern atmospheric CO2 concentration compared to 3 billion years ago. PMID:25583135

  6. Enhancing the Properties of Carbon and Gold Substrates by Surface Modification

    Energy Technology Data Exchange (ETDEWEB)

    Harnisch, Jennifer Anne [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    The properties of both carbon and gold substrates are easily affected by the judicious choice of a surface modification protocol. Several such processes for altering surface composition have been published in literature. The research presented in this thesis primarily focuses on the development of on-column methods to modify carbon stationary phases used in electrochemically modulated liquid chromatography (EMLC). To this end, both porous graphitic carbon (PGC) and glassy carbon (GC) particles have been modified on-column by the electroreduction of arenediazonium salts and the oxidation of arylacetate anions (the Kolbe reaction). Once modified, the carbon stationary phases show enhanced chromatographic performance both in conventional liquid chromatographic columns and EMLC columns. Additionally, one may also exploit the creation of aryl films to by electroreduction of arenediazonium salts in the creation of nanostructured materials. The formation of mercaptobenzene film on the surface of a GC electrode provides a linking platform for the chemisorption of gold nanoparticles. After deposition of nanoparticles, the surface chemistry of the gold can be further altered by self-assembled monolayer (SAM) formation via the chemisorption of a second thiol species. Finally, the properties of gold films can be altered such that they display carbon-like behavior through the formation of benzenehexathiol (BHT) SAMs. BHT chemisorbs to the gold surface in a previously unprecedented planar fashion. Carbon and gold substrates can be chemically altered by several methodologies resulting in new surface properties. The development of modification protocols and their application in the analytical arena is considered herein.

  7. Electronic structure of incident carbon ions on a graphite surface

    International Nuclear Information System (INIS)

    Kiuchi, Masato; Takeuchi, Takae; Yamamoto, Masao.

    1997-01-01

    The electronic structure of an incident carbon ion on a graphite surface is discussed on the basis of ab initio molecular orbital calculations. A carbon cation forms a covalent bond with the graphite, and a carbon nonion is attracted to the graphite surface through van der Waals interaction. A carbon anion has no stable state on a graphite surface. The charge effects of incident ions become clear upon detailed examination of the electronic structure. (author)

  8. Bainite formation kinetics in high carbon alloyed steel

    International Nuclear Information System (INIS)

    Luzginova, N.V.; Zhao, L.; Sietsma, J.

    2008-01-01

    In recent years, many investigations have been carried out on the modeling of the bainite formation. In the present work, a physical approach proposed in the literature is implemented to model the formation of lower bainite in high carbon steels (1 wt.% C). In this model, the carbon diffusion is assumed to control the kinetics of the bainite formation. Both the nucleation and the growth rates are considered in an Avrami type analysis. The effect of alloying elements is taken into account considering only the thermodynamics of the system. The results and the physical meaning of the model parameters are discussed. It is shown that the diffusional approach gives a reasonable description of bainite formation kinetics in high carbon steel. Only two fitting parameters are used: the first accounts for carbon grain-boundary diffusion and the second is the initial nucleation-site density. The model satisfactorily accounts for the effect of transformation temperature, but does not take into account the carbide precipitation during bainite formation and the effect of alloying elements on the diffusion coefficient of carbon

  9. High surface area carbon and process for its production

    Energy Technology Data Exchange (ETDEWEB)

    Romanos, Jimmy; Burress, Jacob; Pfeifer, Peter; Rash, Tyler; Shah, Parag; Suppes, Galen

    2016-12-13

    Activated carbon materials and methods of producing and using activated carbon materials are provided. In particular, biomass-derived activated carbon materials and processes of producing the activated carbon materials with prespecified surface areas and pore size distributions are provided. Activated carbon materials with preselected high specific surface areas, porosities, sub-nm (<1 nm) pore volumes, and supra-nm (1-5 nm) pore volumes may be achieved by controlling the degree of carbon consumption and metallic potassium intercalation into the carbon lattice during the activation process.

  10. Apparatus and process for the surface treatment of carbon fibers

    Science.gov (United States)

    Paulauskas, Felix Leonard; Ozcan, Soydan; Naskar, Amit K.

    2016-05-17

    A method for surface treating a carbon-containing material in which carbon-containing material is reacted with decomposing ozone in a reactor (e.g., a hollow tube reactor), wherein a concentration of ozone is maintained throughout the reactor by appropriate selection of at least processing temperature, gas stream flow rate, reactor dimensions, ozone concentration entering the reactor, and position of one or more ozone inlets (ports) in the reactor, wherein the method produces a surface-oxidized carbon or carbon-containing material, preferably having a surface atomic oxygen content of at least 15%. The resulting surface-oxidized carbon material and solid composites made therefrom are also described.

  11. Carbonate Mineral Formation on Mars: Clues from Stable Isotope Variation Seen in Cryogenic Laboratory Studies of Carbonate Salts

    Science.gov (United States)

    Socki, Richard; Niles, Paul B.; Sun, Tao; Fu, Qi; Romanek, Christopher S.; Gibson, Everett K.

    2013-01-01

    The geologic history of water on the planet Mars is intimately connected to the formation of carbonate minerals through atmospheric CO2 and its control of the climate history of Mars. Carbonate mineral formation under modern martian atmospheric conditions could be a critical factor in controlling the martian climate in a means similar to the rock weathering cycle on Earth. The combination of evidence for liquid water on the martian surface and cold surface conditions suggest fluid freezing could be very common on the surface of Mars. Cryogenic calcite forms readily when a rise in pH occurs as a result of carbon dioxide degassing quickly from freezing Ca-bicarbonate-rich water solutions. This is a process that has been observed in some terrestrial settings such as arctic permafrost cave deposits, lakebeds of the Dry Valleys of Antarctica, and in aufeis (river icings) from rivers of N.E. Alaska. We report here the results of a series of laboratory experiments that were conducted to simulate potential cryogenic carbonate formation on the planet Mars. These results indicate that carbonates grown under martian conditions (controlled atmospheric pressure and temperature) show enrichments from starting bicarbonate fluids in both carbon and oxygen isotopes beyond equilibrium values with average delta13C(DIC-CARB) values of 20.5%0 which exceed the expected equilibrium fractionation factor of [10(sup 3) ln alpha = 13%0] at 0 degC. Oxygen isotopes showed a smaller enrichment with delta18O(H2O-CARB) values of 35.5%0, slightly exceeding the equilibrium fractionation factor of [10(sup 3) ln alpha = 34%0 ] at 0degC. Large kinetic carbon isotope effects during carbonate precipitation could substantially affect the carbon isotope evolution of CO2 on Mars allowing for more efficient removal of 13C from the Noachian atmosphere enriched by atmospheric loss. This mechanism would be consistent with the observations of large carbon isotope variations in martian materials despite the

  12. Improvement of carbon fibre surface properties using electron beam irradiation

    International Nuclear Information System (INIS)

    Eddy Segura Pino; Luci Diva Brocardo Machado; Claudia Giovedi

    2006-01-01

    Carbon fiber-reinforced advance composites have been used for structural applications, mainly due to their mechanical properties, and additional features such as high strength-to-weight ratio, stiffness-to-weight ratio, corrosion resistance and wear properties. The main factor for a good mechanical performance of carbon fiber-reinforced composite is the interfacial interaction between the components that are fiber and polymeric matrix. The greatest challenge is to improve adhesion between components having elasticity modulus which differ by orders of magnitude and furthermore they are immiscible in each other. Another important factor is the sizing material on the carbon fiber, which protects the carbon fiber filaments and must be compatible with the matrix material in order to improve the adhesion process. The interaction of ionizing radiation from electron beam can induce in the irradiated material the formation of very active centers and free radicals. Further evolution of these active species can significantly modify structure and properties not only in the irradiated polymeric matrix but also on the fiber surface. So that, fiber and matrix play an important role in the production of chemical bonds, which promote better adhesion between both materials improving the composite mechanical performance. The aim of this work was to improve the surface properties of the carbon fiber surface using ionizing radiation from an electron beam in order to obtain improvement of the adhesion properties in the resulted composite. Commercial carbon fiber roving of high tensile strength with 12 000 filaments named 12 k, and sizing material of epoxy resin modified by ester groups was studied. EB irradiation has been carried out at the Institute for Nuclear and Energy Research (IPEN) facilities using a 1.5 MeV 37.5 kW Dynamitron electron accelerator model JOB-188. Rovings of carbon fibers with 1.78 g cm -3 density and 0.13 mm thickness were irradiated with 0.555 MeV, 6.43 mA and

  13. Distribution of uranium in the carbonate rock of Um Bogma formation, Southwest, Sinai, Egypt

    International Nuclear Information System (INIS)

    El-AAssy, I.E.; Ahmed, F.Y.; Morsy, A.M.; El-Fawal, F.M.; Mansour, M.Gh.

    1998-01-01

    The lower carboniferous Um bogma Formation is a potential source for Mn, Cu and U. it is mainly composed of dolostone and limestone with few clastic different interbeds of clay stone, siltstone and sandstone. The different diagenetic processes which affected this formation are mainly, compaction, cementation, neomorphism, dissolution, dolomitization, silicification and filling the veins and pores. The distribution of uranium and thorium within the three members and their correlation with the iron oxides and organic matter, were studied. The channel porosity and intercrystalline spaces which resulted from dolomitization acted as pathways for uraniferous solutions in the carbonate rocks. On the other hand, the shales and clay stones underneath the carbonates of Um bogma formation acted as barriers and good depositional environment for the accumulation of uranium on the surfaces of joints and fractures.The accumulated uranium minerals in the carbonate rocks are most likely of the efflorescent deposits

  14. Role of carbon impurities on the surface morphology evolution of tungsten under high dose helium ion irradiation

    International Nuclear Information System (INIS)

    Al-Ajlony, A.; Tripathi, J.K.; Hassanein, A.

    2015-01-01

    The effect of carbon impurities on the surface evolution (e.g., fuzz formation) of tungsten (W) surface during 300 eV He ions irradiation was studied. Several tungsten samples were irradiated by He ion beam with a various carbon ions percentage. The presence of minute carbon contamination within the He ion beam was found to be effective in preventing the fuzz formation. At higher carbon concentration, the W surface was found to be fully covered with a thick graphitic layer on the top of tungsten carbide (WC) layer that cover the sample surface. Lowering the ion beam carbon percentage was effective in a significant reduction in the thickness of the surface graphite layer. Under these conditions the W surface was also found to be immune for the fuzz formation. The effect of W fuzz prevention by the WC formation on the sample surface was more noticeable when the He ion beam had much lower carbon (C) ions content (0.01% C). In this case, the fuzz formation was prevented on the vast majority of the W sample surface, while W fuzz was found in limited and isolated areas. The W surface also shows good resistance to morphology evolution when bombarded by high flux of pure H ions at 900 °C. - Highlights: • Reporting formation of W nanostructure (fuzz) due to low energy He ion beam irradiation. • The effect of adding various percentage of carbon impurity to the He ion beam on the trend of W fuzz formation was studied. • Mitigation of W fuzz formation due to addition of small percentage of carbon to the He ion beam is reported. • The formation of long W nanowires due to He ion beam irradiation mixed with 0.01% carbon ions is reported.

  15. The formation of ethane from carbon dioxide under cold plasma

    International Nuclear Information System (INIS)

    Zhang Xiuling; Zhang Lin; Dai Bin; Gong Weimin; Liu Changhou

    2001-01-01

    Pulsed-corona plasma has been used as a new method for ethane dehydrogenation at low temperature and normal pressure using carbon dioxide as an oxidant. The effect of carbon dioxide content in the feed, power input, and flow rate of the reactants on the ethane dehydrogenation has been investigated. The experimental results show that the conversion of ethane increases with the increasing in the amount of carbon dioxide in the feed. The yield of ethylene and acetylene decreases with the increasing in the yield of carbon monoxide, indicating that the increased carbon dioxide leads to the part of ethylene and acetylene being oxidized to carbon monoxide. Power input is primarily an electrical parameter in pulsed-corona plasma, which plays an important role in reactant conversion and product formation. When the power input reaches 16 W, ethane conversion is 41.0% and carbon dioxide conversion is 26.3%. The total yield of ethylene and acetylene is 15.6%. The reduced flow rate of feed improves the conversion of ethane, carbon dioxide and the yield of acetylene, and induces carbon deposit as well

  16. General aspects of surface alloy formation

    Energy Technology Data Exchange (ETDEWEB)

    Bergbreiter, Andreas; Engstfeld, Albert K.; Roetter, Ralf T.; Hoster, Harry E.; Behm, R. Juergen [Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm (Germany); Berko, Andras

    2010-07-01

    Surface confined alloys are excellent model systems for studies of structure-property relationships of bimetallic surfaces. They are formed by deposition of a guest metal B onto a substrate A, followed by annealing to a temperature, where place exchange between adatoms and atoms from the underlying surface layer becomes possible and diffusion into the bulk is sufficiently slow. We exemplarily confirmed by scanning tunneling microscopy and Auger electron spectroscopy for PtRu/Ru(0001), PdRu/Ru(0001), AuPt/Pt(111), AgPt/Pt(111), and AgPd/Pd(111), surface alloys are obtained for systems where metal B has a negative surface segregation energy within metal A. By exchanging A and B, however, AB surface alloys are most likely overgrown by metal B, which we demonstrate for RuPt/Pt(111) in comparison to PtRu/Ru(0001).

  17. Policy interactions, risk and price formation in carbon markets

    International Nuclear Information System (INIS)

    Blyth, William; Bunn, Derek; Kettunen, Janne; Wilson, Tom

    2009-01-01

    Carbon pricing is an important mechanism for providing companies with incentives to invest in carbon abatement. Price formation in carbon markets involves a complex interplay between policy targets, dynamic technology costs, and market rules. Carbon pricing may under-deliver investment due to R and D externalities, requiring additional policies which themselves affect market prices. Also, abatement costs depend on the extent of technology deployment due to learning-by-doing. This paper introduces an analytical framework based on marginal abatement cost (MAC) curves with the aim of providing an intuitive understanding of the key dynamics and risk factors in carbon markets. The framework extends the usual static MAC representation of the market to incorporate policy interactions and some technology cost dynamics. The analysis indicates that supporting large-scale deployment of mature abatement technologies suppresses the marginal cost of abatement, sometimes to zero, whilst increasing total abatement costs. However, support for early stage R and D may reduce both total abatement cost and carbon price risk. An important aspect of the analysis is in elevating risk management considerations into energy policy formation, as the results of the stochastic modelling indicate wide distributions for the emergence of carbon prices and public costs around the policy expectations. (author)

  18. Calcium carbonate nucleation in an alkaline lake surface water, Pyramid Lake, Nevada, USA

    Science.gov (United States)

    Reddy, Michael M.; Hoch, Anthony

    2012-01-01

    Calcium concentration and calcite supersaturation (Ω) needed for calcium carbonate nucleation and crystal growth in Pyramid Lake (PL) surface water were determined during August of 1997, 2000, and 2001. PL surface water has Ω values of 10-16. Notwithstanding high Ω, calcium carbonate growth did not occur on aragonite single crystals suspended PL surface water for several months. However, calcium solution addition to PL surface-water samples caused reproducible calcium carbonate mineral nucleation and crystal growth. Mean PL surface-water calcium concentration at nucleation was 2.33 mM (n = 10), a value about nine times higher than the ambient PL surface-water calcium concentration (0.26 mM); mean Ω at nucleation (109 with a standard deviation of 8) is about eight times the PL surface-water Ω. Calcium concentration and Ω regulated the calcium carbonate formation in PL nucleation experiments and surface water. Unfiltered samples nucleated at lower Ω than filtered samples. Calcium concentration and Ω at nucleation for experiments in the presence of added particles were within one standard deviation of the mean for all samples. Calcium carbonate formation rates followed a simple rate expression of the form, rate (mM/min) = A (Ω) + B. The best fit rate equation "Rate (Δ mM/Δ min) = -0.0026 Ω + 0.0175 (r = 0.904, n = 10)" was statistically significant at greater than the 0.01 confidence level and gives, after rearrangement, Ω at zero rate of 6.7. Nucleation in PL surface water and morphology of calcium carbonate particles formed in PL nucleation experiments and in PL surface-water samples suggest crystal growth inhibition by multiple substances present in PL surface water mediates PL calcium carbonate formation, but there is insufficient information to determine the chemical nature of all inhibitors.

  19. Formation control of marine surface craft: a Lagrangian approach

    DEFF Research Database (Denmark)

    Ihle, Ivar-Andre F.; Jouffroy, Jerome; Fossen, Thor I.

    2006-01-01

    This paper presents a method for formation control of marine surface craft inspired by Lagrangian mechanics. The desired formation configuration and response of the marine surface craft are given as a set of constraints in analytical mechanics. Thus, constraints forces arise and feedback from...

  20. Low-energy electron irradiation induced top-surface nanocrystallization of amorphous carbon film

    Science.gov (United States)

    Chen, Cheng; Fan, Xue; Diao, Dongfeng

    2016-10-01

    We report a low-energy electron irradiation method to nanocrystallize the top-surface of amorphous carbon film in electron cyclotron resonance plasma system. The nanostructure evolution of the carbon film as a function of electron irradiation density and time was examined by transmission electron microscope (TEM) and Raman spectroscopy. The results showed that the electron irradiation gave rise to the formation of sp2 nanocrystallites in the film top-surface within 4 nm thickness. The formation of sp2 nanocrystallite was ascribed to the inelastic electron scattering in the top-surface of carbon film. The frictional property of low-energy electron irradiated film was measured by a pin-on-disk tribometer. The sp2 nanocrystallized top-surface induced a lower friction coefficient than that of the original pure amorphous film. This method enables a convenient nanocrystallization of amorphous surface.

  1. The Heat of Combustion of Tobacco and Carbon Oxide Formation

    Directory of Open Access Journals (Sweden)

    Norman AB

    2014-12-01

    Full Text Available Recent studies demonstrated a relationship between mass burn rates of straight-grade cigarettes and heats of combustion of the tobacco materials. In the present work, relationships between measured heats of combustion and elemental composition of the tobacco materials were further analyzed. Heats of combustion measured in oxygen were directly correlated with the carbon and hydrogen content of the tobacco materials tested. Ash content of the materials was inversely related to the heats of combustion. The water insoluble residues from exhaustively extracted tobacco materials showed higher heats of combustion and higher carbon content than the non-extracted materials, confirming a direct relationship between carbon content and heat of combustion. A value for the heat of formation of tobacco was estimated (1175 cal/g from the heat of combustion data and elemental analysis results. The estimated value for heat of formation of tobacco appears to be constant regardless of the material type. Heat values measured in air were uniformly lower than the combustion heats in oxygen, suggesting formation of CO and other reaction products. Gases produced during bomb calorimetry experiments with five tobacco materials were analyzed for CO and CO2 content. When the materials were burned in oxygen, no CO was found in the gases produced. Measured heats of combustion matched estimates based on CO2 found in the gas and conversion of the sample hydrogen content to water. Materials burned in air produced CO2 (56% to 77% of the sample carbon content and appreciable amounts of CO (7% to 16% of the sample carbon content. Unburned residue containing carbon and hydrogen was found in the air combustion experiments. Estimated heat values based on amounts of CO and CO2 found in the gas and water formed from the hydrogen lost during combustion in air were higher than the measured values. These observations indicate formation of products containing hydrogen when the materials

  2. Robust combined position and formation control for marine surface craft

    DEFF Research Database (Denmark)

    Ihle, Ivar-Andre F.; Jouffroy, Jerome; Fossen, Thor I.

    We consider the robustness properties of a formation control system for marine surface vessels. Intervessel constraint functions are stabilized to achieve the desired formation configuration. We show that the formation dynamics is Input-to-State Stable (ISS) to both environmental perturbations th...

  3. Inherent-opening-controlled pattern formation in carbon nanotube arrays

    International Nuclear Information System (INIS)

    Huang Xiao; Zhou, Jijie J; Sansom, Elijah; Gharib, Morteza; Haur, Sow Chorng

    2007-01-01

    We have introduced inherent openings into densely packed carbon nanotube arrays to study self-organized pattern formation when the arrays undergo a wetting-dewetting treatment from nanotube tips. These inherent openings, made of circular or elongated hollows in nanotube mats, serve as dewetting centres, from where liquid recedes from. As the dewetting centres initiate dry zones and the dry zones expand, surrounding nanotubes are pulled away from the dewetting centres by liquid surface tension. Among short nanotubes, the self-organized patterns are consistent with the shape of the inherent openings, i.e. slender openings lead to elongated trench-like structures, and circular holes result in relatively round nest-like arrangements. Nanotubes in a relatively high mat are more connected, like in an elastic body, than those in a short mat. Small cracks often initialize themselves in a relatively high mat, along two or more adjacent round openings; each of the cracks evolves into a trench as liquid dries up. Self-organized pattern control with inherent openings needs to initiate the dewetting process above the nanotube tips. If there is no liquid on top, inherent openings barely enlarge themselves after the wetting-dewetting treatment

  4. The Role of Carbon in Exotic Crust Formation on Mercury

    Science.gov (United States)

    Vander Kaaden, Kathleen E.; McCubbin, Francis M.

    2018-01-01

    The terrestrial planets that comprise our inner Solar System, including the Moon, are all rocky bodies that have differentiated into a crust, mantle, and core. Furthermore, all of these bodies have undergone various igneous processes since their time of primary crust formation. These processes have resurfaced each of these bodies, at least in part, resulting in the production of a secondary crust, to which Mercury is no exception. From its first flyby encounter with Mercury on January 14, 2008, the MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) spacecraft collected data on the structure, chemical makeup, and density of the planet among other important characteristics. The X-Ray Spectrometer on board MESSENGER measured elevated abundances of sulfur and low abundances of iron, suggesting the planets oxygen fugacity (fO2) is several log10 units below the Iron-Wustite buffer. Similar to the role of other volatiles (e.g. sulfur) on highly reducing planetary bodies, carbon is expected to behave differently in an oxygen starved environment than it does in an oxygen enriched environment (e.g., Earth).

  5. Scaling of Calcium Carbonate at Heated Surfaces in a Continuous System

    OpenAIRE

    Nergaard, Margrethe

    2011-01-01

    Scaling is the precipitation of a mineral layer on a surface. Sparingly soluble salts with inverse solubility, which calcium carbonate exhibits, will prefer precipitation at heated surfaces, making heat exchangers a target for scale formation. A continuous setup was used to study scale formation, the nature of the scale formed and scaling rate. An internally heated U-shaped tube was inserted into a continuously stirred tank, giving the same conditions for all scaling points. The experimental ...

  6. Surface diffusion of carbon atom and carbon dimer on Si(0 0 1) surface

    International Nuclear Information System (INIS)

    Zhu, J.; Pan, Z.Y.; Wang, Y.X.; Wei, Q.; Zang, L.K.; Zhou, L.; Liu, T.J.; Jiang, X.M.

    2007-01-01

    Carbon (C) atom and carbon dimer (C2) are known to be the main projectiles in the deposition of diamond-like carbon (DLC) films. The adsorption and diffusion of the C adatom and addimer (C2) on the fully relaxed Si(0 0 1)-(2 x 1) surface was studied by a combination of the molecular dynamics (MD) and Monte Carlo (MC) simulation. The adsorption sites of the C and C2 on the surface and the potential barriers between these sites were first determined using the semi-empirical many-body Brenner and Tersoff potential. We then estimated their hopping rates and traced their pathways. It is found that the diffusion of both C and C2 is strongly anisotropic in nature. In addition, the C adatom can diffuse a long distance on the surface while the adsorbed C2 is more likely to be confined in a local region. Thus we can expect that smoother films will be formed on the Si(0 0 1) surface with single C atoms as projectile at moderate temperature, while with C2 the films will grow in two-dimensional islands. In addition, relatively higher kinetic energy of the projectile, say, a few tens of eV, is needed to grow DLC films of higher quality. This is consistent with experimental findings

  7. Carbon Monoxide Hydrogenation on Ice Surfaces.

    Science.gov (United States)

    Kuwahata, Kazuaki; Ohno, Kaoru

    2018-03-14

    We have performed density functional calculations to investigate the carbon monoxide hydrogenation reaction (H+CO→HCO), which is important in interstellar clouds. We found that the activation energy of the reaction on amorphous ice is lower than that on crystalline ice. In the course of this study, we demonstrated that it is roughly possible to use the excitation energy of the reactant molecule (CO) in place of the activation energy. This relationship holds also for small water clusters at the CCSD level of calculation and the two-layer-level ONIOM (CCSD : X3LYP) calculation. Generally, since it is computationally demanding to estimate activation energies of chemical reactions in a circumstance of many water molecules, this relationship enables one to determine the activation energy of this reaction on ice surfaces from the knowledge of the excitation energy of CO only. Incorporating quantum-tunneling effects, we discuss the reaction rate on ice surfaces. Our estimate that the reaction rate on amorphous ice is almost twice as large as that on crystalline ice is qualitatively consistent with the experimental evidence reported by Hidaka et al. [Chem. Phys. Lett., 2008, 456, 36.]. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Shewanella putrefaciens adhesion and biofilm formation on food processing surfaces

    DEFF Research Database (Denmark)

    Bagge, Dorthe; Hjelm, M.; Johansen, C.

    2001-01-01

    Laboratory model systems were developed for studying Shewanella putrefaciens adhesion and biofilm formation under batch and flow conditions. S. putrefaciens plays a major role in food spoilage and may cause microbially induced corrosion on steel surfaces. S. putrefaciens bacteria suspended in buf...... from surfaces, and indirect conductometry and found this combination sufficient to quantify bacteria on surfaces...

  9. Carbon Disulfide (CS2) Mechanisms in Formation of Atmospheric Carbon Dioxide (CO2) Formation from Unconventional Shale Gas Extraction and Processing Operations and Global Climate Change.

    Science.gov (United States)

    Rich, Alisa L; Patel, Jay T

    2015-01-01

    Carbon disulfide (CS2) has been historically associated with the production of rayon, cellophane, and carbon tetrachloride. This study identifies multiple mechanisms by which CS2 contributes to the formation of CO2 in the atmosphere. CS2 and other associated sulfide compounds were found by this study to be present in emissions from unconventional shale gas extraction and processing (E&P) operations. The breakdown products of CS2; carbonyl sulfide (COS), carbon monoxide (CO), and sulfur dioxide (SO2) are indirect greenhouse gases (GHGs) that contribute to CO2 levels in the atmosphere. The heat-trapping nature of CO2 has been found to increase the surface temperature, resulting in regional and global climate change. The purpose of this study is to identify five mechanisms by which CS2 and the breakdown products of CS2 contribute to atmospheric concentrations of CO2. The five mechanisms of CO2 formation are as follows: Chemical Interaction of CS2 and hydrogen sulfide (H2S) present in natural gas at high temperatures, resulting in CO2 formation;Combustion of CS2 in the presence of oxygen producing SO2 and CO2;Photolysis of CS2 leading to the formation of COS, CO, and SO2, which are indirect contributors to CO2 formation;One-step hydrolysis of CS2, producing reactive intermediates and ultimately forming H2S and CO2;Two-step hydrolysis of CS2 forming the reactive COS intermediate that reacts with an additional water molecule, ultimately forming H2S and CO2. CS2 and COS additionally are implicated in the formation of SO2 in the stratosphere and/or troposphere. SO2 is an indirect contributor to CO2 formation and is implicated in global climate change.

  10. HFCVD growth of various carbon nanostructures on SWCNT paper controlled by surface treatment

    International Nuclear Information System (INIS)

    Varga, M.; Izak, T.; Kromka, A.; Kotlar, M.; Vretenar, V.; Ledinsky, M.; Michalka, M.; Skakalova, V.; Vesely, M.

    2012-01-01

    In this article, we investigate the nanocomposite material formation, particularly the deposition of nanocrystalline diamond and carbon nanowalls (CNWs) on single-wall carbon nanotubes buckypaper (BP). One part of the buckypaper substrate was nucleated by nanodiamond powder. The growth was carried out in a hot filament chemical vapor deposition (HFCVD) system. Contact angle measurements, scanning electron microscopy, and Raman spectroscopy were used for the surface morphology analysis and characterization of carbon phases. Due to a different surface pretreatment, different carbon nanostructures were formed: diamond film was grown on the nucleated BP area; non-treated area of the BP was covered with a dense field of CNWs. Covering a part of the BP surface prevented an access of the HF-plasma and so the growth of any carbon structures. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Multiwalled Carbon Nanotube Deposition on Model Environmental Surfaces

    Science.gov (United States)

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

  12. Carbon dioxide hydrate formation in a fixed-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Fan, S.; Lang, X. [South China Univ. of Technology, Guangzhou (China). Key Laboratory of Enhanced Heat Transfer and Energy Conservation; Wang, Y.; Liang, D. [Chinese Academy of Sciences, Guangzhou (China). Guangzhou Inst. of Energy Conversion and Guangzhou Center of Natural Gas Hydrate; Sun, X.; Jurcik, B. [Air Liquide Laboratories, Tsukuba (Japan)

    2008-07-01

    Gas hydrates are thermodynamically stable at high pressures and near the freezing temperature of pure water. Methane hydrates occur naturally in sediments in the deep oceans and permafrost regions and constitute an extensive hydrocarbon reservoir. Carbon dioxide (CO{sub 2}) hydrates are of interest as a medium for marine sequestration of anthropogenic carbon dioxide. Sequestering CO{sub 2} as hydrate has potential advantages over most methods proposed for marine CO{sub 2} sequestration. Because this technique requires a shallower depth of injection when compared with other ocean sequestration methods, the costs of CO{sub 2} hydrate sequestration may be lower. Many studies have successfully used different continuous reactor designs to produce CO{sub 2} hydrates in both laboratory and field settings. This paper discussed a study that involved the design and construction of a fixed-bed reactor for simulation of hydrate formation system. Water, river sands and carbon dioxide were used to simulate the seep kind of hydrate formation. Carbon dioxide gas was distributed as small bubbles to enter from the bottom of the fixed-bed reactor. The paper discussed the experimental data and presented a diagram of the gas hydrate reactor system. The morphology as well as the reaction characters of CO{sub 2} hydrate was presented in detail. The results were discussed in terms of experimental phenomena and hydrate formation rate. A mathematical model was proposed for describing the process. 17 refs., 7 figs.

  13. Adsorption of water and carbon dioxide on hematite and consequences for possible hydrate formation.

    Science.gov (United States)

    Kvamme, Bjørn; Kuznetsova, Tatiana; Kivelae, Pilvi-Helina

    2012-04-07

    The interest in carbon dioxide for enhanced oil recovery is increasing proportional to the decline in naturally driven oil production and also due to the increasing demand for reduced emission of carbon dioxide into the atmosphere. Transport of carbon dioxide in offshore pipelines involves high pressure and low temperatures, conditions which may lead to formation of hydrates from residual water dissolved in carbon dioxide and carbon dioxide. The critical question is whether the water at certain temperatures and pressures will drop out as liquid droplets first, and then form hydrates, or alternatively, adsorb on the pipeline surfaces, and subsequently form hydrates heterogeneously. In this work, we used several different basis sets of density functional theory in ab initio calculations to estimate the charge distribution of hematite (the dominating component of rust) crystals. These rust particles were embedded in water and chemical potential for adsorbed water molecules was estimated through thermodynamic integration and compared to similar estimates for water clusters of the same size. While the generated charges were not unique, the use of high order approximations and different basis sets provides a range of likely charge distributions. Values obtained for the chemical potential of water in different surroundings indicated that it would be thermodynamically favorable for water to adsorb on hematite, and that evaluation of potential carbon dioxide hydrate formation conditions and kinetics should be based on this formation mechanism. Depending on the basis set and approximations, the estimated gain for water to adsorb on the hematite surface rather than condense as droplets varied between -1.7 kJ mole(-1) and -3.4 kJ mole(-1). The partial charge distribution on the hematite surface is incompatible with the hydrate structure, and thus hydrates will be unable to attach to the surface. The behavior of water outside the immediate vicinity of hematite (beyond 3

  14. Carbon formation and metal dusting in advanced coal gasification processes

    Energy Technology Data Exchange (ETDEWEB)

    DeVan, J.H.; Tortorelli, P.F.; Judkins, R.R.; Wright, I.G.

    1997-02-01

    The product gases generated by coal gasification systems contain high concentrations of CO and, characteristically, have relatively high carbon activities. Accordingly, carbon deposition and metal dusting can potentially degrade the operation of such gasifier systems. Therefore, the product gas compositions of eight representative gasifier systems were examined with respect to the carbon activity of the gases at temperatures ranging from 480 to 1,090 C. Phase stability calculations indicated that Fe{sub 3}C is stable only under very limited thermodynamic conditions and with certain kinetic assumptions and that FeO and Fe{sub 0.877}S tend to form instead of the carbide. As formation of Fe{sub 3}C is a necessary step in the metal dusting of steels, there are numerous gasifier environments where this type of carbon-related degradation will not occur, particularly under conditions associated with higher oxygen and sulfur activities. These calculations also indicated that the removal of H{sub 2}S by a hot-gas cleanup system may have less effect on the formation of Fe{sub 3}C in air-blown gasifier environments, where the iron oxide phase can exist and is unaffected by the removal of sulfur, than in oxygen-blown systems, where iron sulfide provides the only potential barrier to Fe{sub 3}C formation. Use of carbon- and/or low-alloy steels dictates that the process gas composition be such that Fe{sub 3}C cannot form if the potential for metal dusting is to be eliminated. Alternatively, process modifications could include the reintroduction of hydrogen sulfide, cooling the gas to perhaps as low as 400 C and/or steam injection. If higher-alloy steels are used, a hydrogen sulfide-free gas may be processed without concern about carbon deposition and metal dusting.

  15. Influence of surface vacancy defects on the carburisation of Fe 110 surface by carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Chakrabarty, Aurab, E-mail: aurab.chakrabarty@qatar.tamu.edu; Bouhali, Othmane [Texas A& M University at Qatar, P.O. Box 23874, Doha (Qatar); Mousseau, Normand [Département de Physique and RQMP, Université de Montréal, Case Postale 6128, Succursale Centre-Ville, Montréal (QC) H3C 3J7 (Canada); Becquart, Charlotte S. [UMET, UMR CNRS 8207, ENSCL, Université Lille I, 59655 Villeneuve d’Ascq cédex (France); El-Mellouhi, Fedwa, E-mail: felmellouhi@qf.org.qa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 5825 Doha (Qatar)

    2016-07-28

    Adsorption and dissociation of gaseous carbon monoxide (CO) on metal surfaces is one of the most frequently occurring processes of carburisation, known as primary initiator of metal dusting corrosion. Among the various factors that can significantly influence the carburisation process are the intrinsic surface defects such as single surface vacancies occurring at high concentrations due to their low formation energy. Intuitively, adsorption and dissociation barriers of CO are expected to be lowered in the vicinity of a surface vacancy, due to the strong attractive interaction between the vacancy and the C atom. Here the adsorption energies and dissociation pathways of CO on clean and defective Fe 110 surface are explored by means of density functional theory. Interestingly, we find that the O adatom, resulting from the CO dissociation, is unstable in the electron-deficit neighbourhood of the vacancy due to its large electron affinity, and raises the barrier of the carburisation pathway. Still, a full comparative study between the clean surface and the vacancy-defected surface reveals that the complete process of carburisation, starting from adsorption to subsurface diffusion of C, is more favourable in the vicinity of a vacancy defect.

  16. Polygon formation and surface flow on a rotating fluid surface

    DEFF Research Database (Denmark)

    Bergmann, Raymond; Tophøj, Laust Emil Hjerrild; Homan, T. A. M.

    2011-01-01

    We present a study of polygons forming on the free surface of a water flow confined to a stationary cylinder and driven by a rotating bottom plate as described by Jansson et al. (Phys. Rev. Lett., vol. 96, 2006, 174502). In particular, we study the case of a triangular structure, either completely...... there the symmetry breaking proceeds like a low-dimensional linear instability. We show that the circular state and the unstable manifold connecting it with the polygon solution are universal in the sense that very different initial conditions lead to the same circular state and unstable manifold. For a wet triangle......, we measure the surface flows by particle image velocimetry (PIV) and show that there are three vortices present, but that the strength of these vortices is far too weak to account for the rotation velocity of the polygon. We show that partial blocking of the surface flow destroys the polygons and re...

  17. Formation and surface characterization of nanostructured Al2O3 ...

    Indian Academy of Sciences (India)

    Administrator

    Page 1. Electronic Supplementary Material. Graphical abstract. Formation and surface characterization of nanostructured Al2O3–TiO2 coatings by Vairamuthu Raj and Mohamed Sirajudeen Mumjitha. (pp 1411–1418).

  18. Surface martensitization of Carbon steel using Arc Plasma Sintering

    Science.gov (United States)

    Wahyudi, Haris; Dimyati, Arbi; Sebayang, Darwin

    2018-03-01

    In this paper new technology of surface structure modification of steel by short plasma exposure in Arc Plasma Sintering (APS) device is presented. APS is an apparatus working based on plasma generated by DC pulsed current originally used for synthesizing materials via sintering and melting. Plasma exposure in APS was applied into the specimens for 1 and 3 seconds which generate temperature approximately about 1300-1500°C. The SUP9, pearlitic carbon steel samples were used. The hardness, hardening depth and microstructure of the specimens have been investigated by Vickers micro hardness test and Scanning Electron Microscopy (SEM) supported by Energy Dispersive X-Ray Spectroscopy (EDX). The results have showed that the mechanical property was significantly improved due to the formation of single martensitic structures as identified by SEM. The hardness of treated surface evaluated by Vickers hardness test showed significant improvement nearly three time from 190 VHN before to 524 VHN after treatment. Furthermore, EDX confirmed that the formation of martensite layer occurred without altering its composition. The APS also produced uniform hardened layer up to 250 μm. The experiment has demonstrated that arc plasma process was successfully improved the mechanical properties of steel in relatively very short time.

  19. Carbon Sequestration on Surface Mine Lands

    Energy Technology Data Exchange (ETDEWEB)

    Donald Graves; Christopher Barton; Richard Sweigard; Richard Warner; Carmen Agouridis

    2006-03-31

    Since the implementation of the federal Surface Mining Control and Reclamation Act of 1977 (SMCRA) in May of 1978, many opportunities have been lost for the reforestation of surface mines in the eastern United States. Research has shown that excessive compaction of spoil material in the backfilling and grading process is the biggest impediment to the establishment of productive forests as a post-mining land use (Ashby, 1998, Burger et al., 1994, Graves et al., 2000). Stability of mine sites was a prominent concern among regulators and mine operators in the years immediately following the implementation of SMCRA. These concerns resulted in the highly compacted, flatly graded, and consequently unproductive spoils of the early post-SMCRA era. However, there is nothing in the regulations that requires mine sites to be overly compacted as long as stability is achieved. It has been cultural barriers and not regulatory barriers that have contributed to the failure of reforestation efforts under the federal law over the past 27 years. Efforts to change the perception that the federal law and regulations impede effective reforestation techniques and interfere with bond release must be implemented. Demonstration of techniques that lead to the successful reforestation of surface mines is one such method that can be used to change perceptions and protect the forest ecosystems that were indigenous to these areas prior to mining. The University of Kentucky initiated a large-scale reforestation effort to address regulatory and cultural impediments to forest reclamation in 2003. During the three years of this project 383,000 trees were planted on over 556 acres in different physiographic areas of Kentucky (Table 1, Figure 1). Species used for the project were similar to those that existed on the sites before mining was initiated (Table 2). A monitoring program was undertaken to evaluate growth and survival of the planted species as a function of spoil characteristics and

  20. Investigation of the formation of Fe-filled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Reuther, H [Forschungszentrum Dresden-Rossendorf, PO Box 510119, D-01314 Dresden (Germany); Mueller, C; Leonhardt, A; Kutz, M C, E-mail: reuther@fzd.d [Leibniz-Institute of Solid State and Materials Research Dresden, PO Box 270116, D-01171 Dresden (Germany)

    2010-03-01

    The formation of Fe-filled carbon nanotubes by thermal decomposition of ferrocene combined with a Fe-catalyst-nanostructuring on an oxidized Si substrate is investigated in the temperature range of 1015 - 1200 K. The optimal growth conditions for aligned and homogeneous carbon nanotubes are found at 1103 K. Moessbauer spectroscopy (both in transmission geometry and CEMS) was used to analyze and quantify the different formed Fe-phases. In general, {alpha}-Fe, {gamma}-Fe and Fe{sub 3}C are found to form within the carbon nanotubes. Depending on the growth conditions their fractions vary strongly. Moreover, an alignment of the {alpha}-Fe in the tubes could be detected.

  1. Self-organized formation of metal-carbon nanostructures by hyperthermal ion deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hannstein, I.K.

    2006-04-26

    The quasi-simultaneous deposition of mass-selected hyperthermal carbon and metal ions results in a variety of interesting film morphologies, depending on the metal used and the deposition conditions. The observed features are of the order of a few nanometres and are therefore interesting for future potential applications in the various fields of nanotechnology. The present study focuses on the structural analysis of amorphous carbon films containing either copper, silver, gold, or iron using amongst others Rutherford Backscattering Spectroscopy, High Resolution Transmission Electron Microscopy, and Energy Dispersive X-Ray Spectroscopy. The film morphologies found are as follows: copper-containing films consist of copper nanoclusters with sizes ranging from about 3 to 9 nm uniformly distributed throughout the amorphous carbon matrix. The cluster size hereby rises with the copper content of the films. The silver containing films decompose into a pure amorphous carbon film with silver agglomerates at the surface. Both, the gold- and the iron-containing films show a multilayer structure of metal-rich layers with higher cluster density separated by metal-depleted amorphous carbon layers. The layer distances are of the order of up to 15 nm in the case of gold-carbon films and 7 nm in the case of iron-carbon films. The formation of theses different structures cannot be treated in the context of conventional self-organization mechanisms basing upon thermal diffusion and equilibrium thermodynamics. Instead, an ion-induced atomic transport, sputtering effects, and the stability of small metal clusters were taken into account in order to model the structure formation processes. A similar multilayer morphology was recently also reported in the literature for metal-carbon films grown by magnetron sputtering techniques. In order to investigate, whether the mechanisms are the same as in the case of the ion beam deposited films described above, first experiments were conducted

  2. Ring formation on an inclined surface

    Science.gov (United States)

    Deegan, Robert; Du, Xiyu

    2015-11-01

    A drop dried on a solid surface will typically leave a narrow band of solute deposited along the contact line. We examined variations of this deposit due to the inclination of the substrate using numerical simulations of a two-dimensional drop, equivalent to a strip-like drop. An asymptotic analysis of the contact line region predicts that the upslope deposit will grow faster at early times, but the growth of this deposit ends sooner because the upper contact line depins first. From our simulations we find that the deposit can be larger at either the upper or lower contact line depending on the initial drop volume and substrate inclination. For larger drops and steeper inclinations, the early lead in deposited mass at the upper contact line is wiped out by the earlier depinning of the upper contact line and subsequent continued growth at the lower contact line. Conversely, for smaller drops and shallower inclinations, the early lead of the upper contact line is insurmountable despite its earlier termination in growth. Our results show that it is difficult to reconstruct a postiorithe inclination of the substrate based solely on the shape of the deposit. The authors thank the James S. McDonnell Foundation for support through a 21st Century Science Initiative in Studying Complex Systems Research Award, and the National Science Foundation for support under Grant No. 0932600.

  3. Graft polymerization of vynil monomers at carbon black surface (1)

    International Nuclear Information System (INIS)

    Haryono Arumbinang.

    1976-01-01

    Effect of aromatic condensates containing functional group on carbon black surface, effect of pH condensates on carbon black chemisorption, analysis and configuration of functional group, the crystal structure, property measurement standard, particle diameter measurement, oil adsorption, colour capacity, volatile acid content, electric resistence and the volume of the granular or carbon black dust, are given. Electron paramagnetic resonance determination of the amount of free radicals on carbon black surface, its oxidation and effects on the surface and inner structure of carbon black, and graft polymerization by radiation copolymerization, are discussed. Experiments on radiation graft copolymerization by acrylic acid, methacrylate, and glycidol methacrylate, in a vacuum condition, have been carried out. It is concluded that further research on the modification and configuration of carbon black should be developed. (author)

  4. Improvement of carbon fiber surface properties using electron beam irradiation

    International Nuclear Information System (INIS)

    Pino, E.S.; Machado, L.D.B.; Giovedi, C.

    2007-01-01

    Carbon fiber-reinforced advance composites have been used for structural applications, mainly on account of their mechanical properties. The main factor for a good mechanical performance of carbon fiber-reinforced composite is the interfacial interaction between its components, which are carbon fiber and polymeric matrix. The aim of this study is to improve the surface properties of the carbon fiber using ionizing radiation from an electron beam to obtain better adhesion properties in the resultant composite. EB radiation was applied on the carbon fiber itself before preparing test specimens for the mechanical tests. Experimental results showed that EB irradiation improved the tensile strength of carbon fiber samples. The maximum value in tensile strength was reached using doses of about 250 kGy. After breakage, the morphology aspect of the tensile specimens prepared with irradiated and non-irradiated car- bon fibers were evaluated. SEM micrographs showed modifications on the carbon fiber surface. (authors)

  5. Production of metal fullerene surface layer from various media in the process of steel carbonization

    Directory of Open Access Journals (Sweden)

    KUZEEV Iskander Rustemovich

    2018-04-01

    Full Text Available Studies devoted to production of metal fullerene layer in steels when introducing carbon from organic and inorganic media were performed. Barium carbonate was used as an inorganic medium and petroleum pitch was used as an organic medium. In order to generate the required amount of fullerenes in the process of steel samples carbonization, optimal temperature mode was found. The higher temperature, absorption and cohesive effects become less important and polymeric carbon structures destruction processes become more important. On the bottom the temperature is limited by petroleum pitch softening temperature and its transition to low-viscous state in order to enhance molecular mobility and improve the possibility of their diffusion to metal surface. Identification of fullerenes in the surface modified layer was carried out following the methods of IR-Fourier spectrometry and high-performance liquid chromatography. It was found out that nanocarbon structures, formed during carbonization in barium carbonate and petroleum pitch mediums, possess different morphology. In the process of metal carbonization from carbonates medium, the main role in fullerenes synthesis is belonged to catalytic effect of surface with generation of endohedral derivatives in the surface layer; but in the process of carbonization from pitch medium fullerenes are formed during crystallization of the latter and crystallization centers are of fullerene type. Based on theoretical data and dataof spectral and chromatographic analysis, optimal conditions of metal fullerene layer formation in barium carbonate and petroleum pitch mediums were determined. Low cohesion of layer, modified in barium carbonate medium, with metal basis was discovered. That was caused by limited carbon diffusion in the volume of α-Fe. According to the detected mechanism of fullerenes formation on steel surface in gaseous medium, fullerenes are formed on catalytic centers – ferrum atoms, forming thin metal

  6. Multi-scale investigation into the mechanisms of fault mirror formation in seismically active carbonate rocks

    Science.gov (United States)

    Ohl, Markus; Chatzaras, Vasileios; Niemeijer, Andre; King, Helen; Drury, Martyn; Plümper, Oliver

    2017-04-01

    Mirror surfaces along principal slip zones in carbonate rocks have recently received considerable attention as they are thought to form during fault slip at seismic velocities and thus may be a marker for paleo-seismicity (Siman-Tov et al., 2013). Therefore, these structures represent an opportunity to improve our understanding of earthquake mechanics in carbonate faults. Recent investigations reported the formation of fault mirrors in natural rocks as well as in laboratory experiments and connected their occurrence to the development of nano-sized granular material (Spagnuolo et al., 2015). However, the underlying formation and deformation mechanisms of these fault mirrors are still poorly constrained and warrant further research. In order to understand the influence and significance of these fault products on the overall fault behavior, we analysed the micro-, and nanostructural inventory of natural fault samples containing mirror slip surfaces. Here we present first results on the possible formation mechanisms of fault mirrors and associated deformation mechanisms operating in the carbonate fault gouge from two seismically active fault zones in central Greece. Our study specifically focuses on mirror slip surfaces obtained from the Arkitsa fault in the Gulf of Evia and the Schinos fault in the Gulf of Corinth. The Schinos fault was reactivated by a magnitude 6.7 earthquake in 1981 while the Arkitsa fault is thought to have been reactivated by a magnitude 6.9 earthquake in 1894. Our investigations encompass a combination of state-of-the-art analytical techniques including X-ray computed tomography, focused ion beam scanning electron microscopy (FIB-SEM), transmission electron microscopy (TEM) and Raman spectroscopy. Using this multiscale analytical approach, we report decarbonation-reaction structures, considerable calcite twinning and grain welding immediately below the mirror slip surface. Grains or areas indicating decarbonation reactions show a foam

  7. Gasification of carbon deposits on catalysts and metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Figueiredo, J L

    1986-10-01

    'Coke' deposited on catalysts and reactor surfaces includes a variety of carbons of different structures and origins, their reactivities being conveniently assessed by Temperature Programmed Reaction (TPR). The gasification of carbon deposits obtained in the laboratory under well controlled conditions, and the regeneration of coked catalysts from petroleum refining processes are reviewed and discussed. Filamentary carbon deposits, containing dispersed metal particles, behave as supported metal catalysts during gasification, and show high reactivities. Pyrolytic and acid catalysis carbons are less reactive on their own, as the gasification is not catalysed; however, metal components of the catalyst or metal impurities deposited on the surface may enhance gasification. 26 refs., 8 figs., 2 tabs.

  8. Stratigraphy on Oxygen and Carbon Isotope of Paciran Formation East Java

    International Nuclear Information System (INIS)

    Premonowati; R P Koesoemadinata; Harsono-Pringgoprawiro; Wahyoe-S-Hantoro

    2004-01-01

    Paleotemperature fluctuation in tropical zone (centennial and decad al scale) has been known. It's based on stable isotopic analysis from each of unconformity zones. Those boundaries have derived on reef units of shallows marine reef complex of Paciran Formation, Tuban area in Northeast Java Basin. From 25 samples have been choosen on undeformed calcite and analyzed by oxygen and carbon stable isotope. It used to validizing a sea level changes during the formation to Reef 1 to Reef 17 from Paciran formation with sea surface temperature (SST) since 4 Ma until now. On early forming of Reef 1 to Reef 3 (since 4 Ma - 2,88 Ma), sea level occurred marine flooding surface. Since the formation of reef 4 (2,59 Ma) to Reef 8 (1,4 Ma) occurred stagnant temperature and almost to warmer condition. Then, δ 18 O have arise up drastically to 5 0/00 and shows warmer condition to Reef 8 formation, in contrary, the sea level have been arised to Reef 10 formation (0,7 Ma). The temperature have been fluctuated between 0,5 o and 1 o C until the formation of Reef 17 (Early Holocene) and continued to Reef 17 formation at 2 o C based on the rapidity sampling of Po rites sp. Wholly, in centennial scale, since the formation of Reef 4 (2,59 Ma) to Reef 17 (1 Ma), the curve of oxygen stable isotope shows decrease or cooler condition. Those condition have conducted to sea level drop since the formation to Reef 7 and Reef 8. There are 4 periods of interglacial since the formation of Reef 4. The warmer condition indicated since the formation of Reef 9, Reef 11 and Reef 17. Recently, a curve of oxygen isotopes reveals warmer drastically or sea level have been arisen. (author)

  9. STRUCTURAL MODIFICATION OF NEW FORMATIONS IN CEMENT MATRIX USING CARBON NANOTUBE DISPERSIONS AND NANOSILICA

    Directory of Open Access Journals (Sweden)

    B. M. Khroustalev

    2017-01-01

    Full Text Available Complex nanodispersed systems with multi-walled carbon nanotubes and nanodispersed silica have a significant impact on the processes of hydration, hardening and strength gain of construction composites predetermining their durability. While using a scanning electron microscope with an attachment for X-ray microanalysis and a device for infrared spectral analysis investigations have shown that the main effect of the cement matrix modification in the case of adding complex nanodispersed systems is provided by direct influence of hydration processes with subsequent crystallization of new formations. It has been noted that while adding carbon nanotube dispersion and nanosized silica a binding matrix is structured in the form of an extremely dense shell from crystalline hydrate new formations on the surface of solid phases that provides strong binding matrix in cement concrete. The addition effect of carbon nanotubes has been analyzed and quantitatively assessed through an investigation for every case of one sample with nanotubes and one sample without them with the help of a nanoindenter and scanning electron microscope. It is necessary to solve rather complicated challenging task in order to assess quantitatively the addition effect of CNT on material characteristics at a micromechanical level. At the same time it is possible to investigate surface of a concrete sample with one-micron resolution. In this case it is necessary to prepare samples for nanoindentation with exclusion of all CNT defectable effects that have been shown by a SEM. So in this case more adequate method for assessment must be a picoindenter , which combines a test method for nanoindentation with an optical SEM potential. Such equipment is in the stage of in-situ testing process at the Vienna University of Technology. The investigation is based on the fact that the main modification effect of mineral binding matrix while using incorporated complex nanodispersed systems and

  10. The formation of carbon chain molecules in IRC + 10216

    International Nuclear Information System (INIS)

    Howe, D.A.; Millar, T.J.

    1990-01-01

    This paper considers the formation of carbon-chain molecules, including C 2n H, C n S, HC 2n+1 N (n = 1-3) and SiC n (n = 1-4), in the outflowing envelope of the late-type carbon star IRC + 10216. The results suggest that the organo-sulphur species C 2 S and C 3 S can be formed in ion-molecule reactions involving acetylene ions and parent CS and SiS molecules. In addition to ion-molecule processes, neutral-neutral reactions can play a significant role in the formation of hydrocarbons and cyanopolyynes with up to six heavy atoms and in the formation of SiC 4 , and suggest that SiC 3 might be observable. However, the short time-scales available in the outflow are such that the observed abundances of the cyanopolyynes larger than HC 5 N cannot be reproduced using the parent molecules and abundances adopted here. (author)

  11. Reconstruction of limnology and microbialite formation conditions from carbonate clumped isotope thermometry.

    Science.gov (United States)

    Petryshyn, V A; Lim, D; Laval, B L; Brady, A; Slater, G; Tripati, A K

    2015-01-01

    Quantitative tools for deciphering the environment of microbialite formation are relatively limited. For example, the oxygen isotope carbonate-water geothermometer requires assumptions about the isotopic composition of the water of formation. We explored the utility of using 'clumped' isotope thermometry as a tool to study the temperatures of microbialite formation. We studied microbialites recovered from water depths of 10-55 m in Pavilion Lake, and 10-25 m in Kelly Lake, spanning the thermocline in both lakes. We determined the temperature of carbonate growth and the (18)O/(16)O ratio of the waters that microbialites grew in. Results were then compared to current limnological data from the lakes to reconstruct the history of microbialite formation. Modern microbialites collected at shallow depths (11.7 m) in both lakes yield clumped isotope-based temperatures of formation that are within error of summer water temperatures, suggesting that clumped isotope analyses may be used to reconstruct past climates and to probe the environments in which microbialites formed. The deepest microbialites (21.7-55 m) were recovered from below the present-day thermoclines in both lakes and yield radioisotope ages indicating they primarily formed earlier in the Holocene. During this time, pollen data and our reconstructed water (18)O/(16)O ratios indicate a period of aridity, with lower lake levels. At present, there is a close association between both photosynthetic and heterotrophic communities, and carbonate precipitation/microbialite formation, with biosignatures of photosynthetic influences on carbonate detected in microbialites from the photic zone and above the thermocline (i.e., depths of generally <20 m). Given the deeper microbialites are receiving <1% of photosynthetically active radiation (PAR), it is likely these microbialites primarily formed when lower lake levels resulted in microbialites being located higher in the photic zone, in warm surface waters. © 2014 John

  12. Surface properties of activated carbon treated by cold plasma heating

    Energy Technology Data Exchange (ETDEWEB)

    Norikazu, Kurano [Shigematsu works Co. Ltd., 267 Yashita, Iwatsuki 3390046 (Japan); Yamada, Hiroshi [Shigematsu works Co. Ltd., 267 Yashita, Iwatsuki 3390046 (Japan); Yajima, Tatsuhiko [Faculty of Engineering, Saitama Institute of Technology, 1690 Fusoiji, Okabe 3690293 (Japan); Sugiyama, Kazuo [Faculty of Engineering, Saitama University, 255 Shimo-okubo, Sakura-Ku, Saitama 3388570 (Japan)]. E-mail: sugi@apc.saitama-u.ac.jp

    2007-03-12

    To modify the surface properties of activated carbon powders, we have applied the cold plasma treatment method. The cold plasma was used to be generated in the evacuated reactor vessel by 2.45 GHz microwave irradiation. In this paper, changes of surface properties such as distribution of acidic functional groups and roughness morphology were examined. By the cold plasma treatment, activated carbons with large specific surface area of ca. 2000 m{sup 2}/g or more could be prepared in a minute. The amount of every gaseous organic compound adsorbed on the unit gram of treated activated carbons was more increased that on the unit gram of untreated carbons. Especially, the adsorbed amount of carbon disulfide was remarkably increased even if it was compared by the amount per unit surface area. These results suggest that the surface property of the sample was modified by the plasma treatment. It became apparent by observing SEM photographs that dust and impure particles in macropores of activated carbons were far more reduced by the plasma treatment than by the conventional heating in an electric furnace under vacuum. In addition, a bubble-like surface morphology of the sample was observed by AEM measurement. The amount of acidic functional groups at the surface was determined by using the Boehm's titration method. Consequently, the increase of lactone groups and the decrease of carboxyl groups were also observed.

  13. Aerosol formation of Sea-Urchin-like nanostructures of carbon nanotubes on bimetallic nanocomposite particles

    International Nuclear Information System (INIS)

    Kim, S. H.; Wang, C.; Zachariah, M. R.

    2011-01-01

    With the advantage of continuous production of pure carbon nanotubes (CNTs), a new simple aerosol process for the formation of CNTs was developed. A combination of conventional spray pyrolysis and thermal chemical vapor deposition enabled the formation unusual sea-urchin-like carbon nanostructures composed of multi-walled CNTs and metal composite nanoparticles. The CNTs formed were relatively untangled and uniform with a diameter of less than∼10 nm. The key to the formation of CNTs in this way was to create a substrate particle containing both a catalytic and non-catalytic component, which prevented coking. The density of the CNTs grown on the spherical metal nanoparticles could be controlled by perturbing the density of the metal catalysts (Fe) in the host non-catalytic metal particle matrix (Al). Mobility size measurement was identified as a useful technique to real-time characterization of either the catalytic formation of thin carbon layer or CNTs on the surface of the metal aerosol. These materials have shown unique properties in enhancing the thermal conductivity of fluids. Other potential advantages are that the as-produced material can be manipulated easily without the concern of high mobility of conventional nanowires, and then subsequently released at the desired time in an unagglomerated state.

  14. Dissolved Carbon Dioxide in Tropical East Atlantic Surface Waters

    NARCIS (Netherlands)

    Bakker, D.C.E.; Baar, H.J.W. de; Jong, E. de

    1999-01-01

    Variability of dissolved inorganic carbon (DIC) and the fugacity of carbon dioxide (fCO2) is discussed for tropical East Atlantic surface waters in October–November 1993 and May–June 1994. High precipitation associated with the Intertropical Convergence Zone, river input and equatorial upwelling

  15. Atmospheric pressure plasma surface modification of carbon fibres

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Løgstrup Andersen, Tom; Michelsen, Poul

    2008-01-01

    Carbon fibres are continuously treated with dielectric barrier discharge plasma at atmospheric pressure in various gas conditions for adhesion improvement in mind. An x-ray photoelectron spectroscopic analysis indicated that oxygen is effectively introduced onto the carbon fibre surfaces by He, He...

  16. On the carbide formation in high-carbon stainless steel

    International Nuclear Information System (INIS)

    Mujahid, M.; Qureshi, M.I.

    1996-01-01

    Stainless steels containing high Cr as well as carbon contents in excess of 1.5 weight percent have been developed for applications which require high resistance erosion and environmental corrosion. Formation of carbides is one of important parameters for controlling properties of these materials especially erosion characteristics. Percent work includes the study of different type of carbides which from during the heat treatment of these materials. It has been found that precipitation of secondary carbides and the nature of matrix transformation plays an important role in determining the hardness characteristics of these materials. (author)

  17. Uranium reduction by carbon oxide during ore formation

    International Nuclear Information System (INIS)

    Matyash, I.V.; Gavrusevich, I.B.; Pasal'skaya, L.F.; Shcherba, D.I.

    1981-01-01

    Using the method of gas chromatography the gas content in Pre-Cambrian granitoils of various types and in natrometasomatites associted with them is studied. It is established that granites associated with ore-bearing albitites have sharply elevated amounts of CO as compared with granites, which do not include mineralization. Simultaneously in ore samples the absence or sharply low amounts of CO as compared with ore-free samples is observed, that is reverse dependence of CO and ore components. Carbon oxide is the reducing agent of uranium mineralization and alongside with other reducing agents can be a geochemical barrier in the process of ore formation [ru

  18. Spatial Distributions of Metal Atoms During Carbon SWNTs Formation: Measurements and Modelling

    Science.gov (United States)

    Cau, M.; Dorval, N.; Attal-Tretout, B.; Cochon, J. L.; Loiseau, A.; Farhat, S.; Hinkov, I.; Scott, C. D.

    2004-01-01

    Experiments and modelling have been undertaken to clarify the role of metal catalysts during single-wall carbon nanotube formation. For instance, we wonder whether the metal catalyst is active as an atom, a cluster, a liquid or solid nanoparticle [1]. A reactor has been developed for synthesis by continuous CO2-laser vaporisation of a carbon-nickel-cobalt target in laminar helium flow. The laser induced fluorescence technique [2] is applied for local probing of gaseous Ni, Co and CZ species throughout the hot carbon flow of the target heated up to 3500 K. A rapid depletion of C2 in contrast to the spatial extent of metal atoms is observed in the plume (Fig. 1). This asserts that C2 condenses earlier than Ni and Co atoms.[3, 4]. The depletion is even faster when catalysts are present. It may indicate that an interaction between metal atoms and carbon dimers takes place in the gas as soon as they are expelled from the target surface. Two methods of modelling are used: a spatially I-D calculation developed originally for the arc process [5], and a zero-D time dependent calculation, solving the chemical kinetics along the streamlines [6]. The latter includes Ni cluster formation. The peak of C2 density is calculated close to the target surface where the temperature is the highest. In the hot region, C; is dominant. As the carbon products move away from the target and mix with the ambient helium, they recombine into larger clusters, as demonstrated by the peak of C5 density around 1 mm. The profile of Ni-atom density compares fairly well with the measured one (Fig. 2). The early increase is due to the drop of temperature, and the final decrease beyond 6 mm results from Ni cluster formation at the eutectic temperature (approx.1600 K).

  19. Biofilm Formation of Listeria monocytogenes on Various Surfaces

    Directory of Open Access Journals (Sweden)

    M Mahdavi

    2007-10-01

    Full Text Available Introduction & Objective: Listeria monocytogenes is considered as a ubiquitous foodborne pathogen which can lead to serious infections, especially in newborns, elderly, pregnant, and immunocompromised people. The organism has been isolated from many foods and may cause meningitis, septicemia and abortion in pregnant women. Also L. monocytogenes forms biofilms on many food contact surface materials and medical devices. Development of biofilms on many surfaces is a potential source of contamination of foods that may lead to spoilage or transmission of foodborne pathogens. Materials & Methods: Biofilm formation of L. monocytogenes (RITCC 1293 serotype 4a was investigated. Hydrophobicity of L. monocytogenes was measured by MATH method. Then biofilm formation of the organism was assessed at 2, 4, 8, 16 and 20 hours on stainless steel (type 304 no 2B, polyethylene and glass by drop plate method. Results: Results indicated that L. monocytogenes with 85% of hydrophobicity formed biofilm on each of three surfaces. Biofilm formation on stainless steel surfaces was significantly more than other surfaces (p<0.05. Conclusion: The ability of biofilm formation of L. monocytogenes on medical devices and food containers is very important as far as hygiene and disease outbreaks are concerned.

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

    Science.gov (United States)

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

    2016-01-01

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

  1. Effect of carbonization temperatures on biochar formation of bamboo leaves

    Science.gov (United States)

    Pattnaik, D.; Kumar, S.; Bhuyan, S. K.; Mishra, S. C.

    2018-03-01

    Bamboo is a typical plant native in Asia, been used in many sectors, which also produces a large volume of leaves which goes waste and not find its application for any useful purposes; is often considered as a bio-waste and normally incinerated or dumped; as its applications are not yet fully explored. However, some research work done on bamboo fibers for use as a reinforcement in making polymer matrix composite. In the present piece of research work, the influence of burning/carbonization of bamboo leaves (at different temperatures) have been studied and characterized. Proximate analysis gave the fixed carbon content (of ~nearly21%). X-Ray diffraction results revealed the presence of various phases viz. cristobalite (SiO2), Calcite (Ca2O3) etc. accompanied with changes in crystal structures. Fourier transform infrared spectroscopy results showed various modes of vibrations viz. O-H stretching bending of other bonds; (for aromatic benzene derivatives) etc. Scanning Electron Microscopic observation (of morphology) showed irregular stacking arrangements between the randomly spaced lamellae structure, with variation in carbonizing temperature. Results revealed the advantages of pyrolysis process in biochar production/formation. It appears that, the bamboo biochar can have suitable properties for its use as an alternative energy source and also for agricultural applications. Its high porosity and carbon content suggest its application as activated carbon also; after physical or chemical treatments. The present research focuses on extending the frontiers of use of bamboo leaves from being an unutilized biowaste to its conversion into a value added product, which can be compassed in terms of sustainable applications.

  2. Modification of carbon fiber surfaces via grafting with Meldrum's acid

    Science.gov (United States)

    Cuiqin, Fang; Jinxian, Wu; Julin, Wang; Tao, Zhang

    2015-11-01

    The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

  3. Nanoparticles dynamics on a surface: fractal pattern formation and fragmentation

    DEFF Research Database (Denmark)

    Dick, Veronika V.; Solov'yov, Ilia; Solov'yov, Andrey V.

    2010-01-01

    In this paper we review our recent results on the formation and the post-growth relaxation processes of nanofractals on surface. For this study we developed a method which describes the internal dynamics of particles in a fractal and accounts for their diffusion and detachment. We demonstrate...... that these kinetic processes determine the final shape of the islands on surface after post-growth relaxation. We consider different scenarios of fractal relaxation and analyze the time evolution of the island's morphology....

  4. Spontaneous formation of optically induced surface relief gratings

    International Nuclear Information System (INIS)

    Leblond, H; Barille, R; Ahmadi-Kandjani, S; Nunzi, J-M; Ortyl, E; Kucharski, S

    2009-01-01

    We develop a model based on Fick's law of diffusion as a phenomenological description of the molecular motion, and on the coupled mode theory, to describe single-beam surface relief grating formation in azopolymer thin films. The model allows us to explain the mechanism of spontaneous patterning, and self-organization. It allows us to compute the surface relief profile and its evolution, with good agreement with experiments.

  5. Spontaneous formation of optically induced surface relief gratings

    Energy Technology Data Exchange (ETDEWEB)

    Leblond, H; Barille, R; Ahmadi-Kandjani, S; Nunzi, J-M [Laboratoire POMA, Universite d' Angers, CNRS FRE 2988, 2, Bd Lavoisier, 49045 Angers (France); Ortyl, E; Kucharski, S, E-mail: herve.leblond@univ-angers.f [Wroclaw University of Technology, Faculty of Chemistry, Department of Polymer Engineering and Technology, 50-370 Wroclaw (Poland)

    2009-10-28

    We develop a model based on Fick's law of diffusion as a phenomenological description of the molecular motion, and on the coupled mode theory, to describe single-beam surface relief grating formation in azopolymer thin films. The model allows us to explain the mechanism of spontaneous patterning, and self-organization. It allows us to compute the surface relief profile and its evolution, with good agreement with experiments.

  6. Investigations of the ternary system beryllium-carbon-tungsten and analyses of beryllium on carbon surfaces

    International Nuclear Information System (INIS)

    Kost, Florian

    2009-01-01

    Beryllium, carbon and tungsten are planned to be used as first wall materials in the future fusion reactor ITER. The aim of this work is a characterization of mixed material formation induced by thermal load. To this end, model systems (layers) were prepared and investigated, which give insight into the basic physical and chemical concepts. Before investigating ternary systems, the first step was to analyze the binary systems Be/C and Be/W (bottom-up approach), where the differences between the substrates PG (pyrolytic graphite) and HOPG (highly oriented pyrolytic graphite) were of special interest. Particularly X-ray photoelectron spectroscopy (XPS), low energy ion scattering (ISS) and Rutherford backscattering spectroscopy (RBS) were used as analysis methods. Beryllium evaporated on carbon shows an island growth mode, whereas a closed layer can be assumed for layer thicknesses above 0.7 nm. Annealing of the Be/C system induces Be 2 C island formation for T≥770 K. At high temperatures (T≥1170 K), beryllium carbide dissociates, resulting in (metallic) beryllium desorption. For HOPG, carbide formation starts at higher temperatures compared to PG. Activation energies for the diffusion processes were determined by analyzing the decreasing beryllium amount versus annealing time. Surface morphologies were characterized using angle-resolved XPS (ARXPS) and atomic force microscopy (AFM). Experiments were performed to study processes in the Be/W system in the temperature range from 570 to 1270 K. Be 2 W formation starts at 670 K, a complete loss of Be 2 W is observed at 1170 K due to dissociation (and subsequent beryllium desorption). Regarding ternary systems, particularly Be/C/W and C/Be/W were investigated, attaching importance to layer thickness (reservoir) variations. At room temperature, Be 2 C, W 2 C, WC and Be 2 W formation at the respective interfaces was observed. Further Be 2 C is forming with increasing annealing temperatures. Depending on the layer

  7. Nanostructure formation on refractory metal surfaces irradiated by helium plasmas

    International Nuclear Information System (INIS)

    Takamura, Shuichi; Kajita, Shin; Ohno, Noriyasu

    2013-01-01

    Helium defects on plasma-facing refractory metals like tungsten have been studied in fusion sciences from the view point of the effects on metal surface properties, concentrating on the bubble formation. However, the surface morphology over the lower surface temperature range was found recently to be changed drastically, something like cotton down or arborescence, sometimes called as “fuzz”. The formation process, although still open problem, would be discussed in terms of viscoelastic model with the effect of surface tension, taking account of its thermal properties and nano-bubbles inside the thin fibers. Some physical surface characteristics like electron emission, radiation emissivity and sputtering are quite influenced by its forest-like structure. Unipolar arcing has been newly studied by using such a surface structure which makes its initiation controllable. In the present report, other examples of nanostructure formation in a variety of particle incident conditions have been introduced as well as the possibility of its industrial applications to enhance interdisciplinary interests. (author)

  8. Covalent Surface Modifications of Carbon Nanotubes.

    Energy Technology Data Exchange (ETDEWEB)

    Pavia Sanders, Adriana [Sandia National Lab. (SNL-CA), Livermore, CA (United States); O' Bryan, Greg [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2017-07-01

    A report meant to document the chemistries investigated by the author for covalent surface modification of CNTs. Oxidation, cycloaddition, and radical reactions were explored to determine their success at covalently altering the CNT surface. Characterization through infrared spectroscopy, Raman spectroscopy, and thermo gravimetric analysis was performed in order to determine the success of the chemistries employed. This report is not exhaustive and was performed for CNT surface modification exploration as it pertains to the "Next Gen" project.

  9. Evaluation of Mechanical Property of Carbon Fiber/Polypropylene Composite According to Carbon Fiber Surface Treatment

    International Nuclear Information System (INIS)

    Han, Song Hee; Oh, Hyun Ju; Kim, Seong Su

    2013-01-01

    In this study, the mechanical properties of a carbon fiber/polypropylene composite were evaluated according to the carbon fiber surface treatment. Carbon fiber surface treatments such as silane coupling agents and plasma treatment were performed to enhance the interfacial strength between carbon fibers and polypropylene. The treated carbon fiber surface was characterized by XP S, Sem, and single-filament tensile test. The interlaminar shear strength (Ilks) of the composite with respect to the surface treatment was determined by a short beam shear test. The test results showed that the Ilks of the plasma-treated specimen increased with the treatment time. The Ilks of the specimen treated with a silane coupling agent after plasma treatment increased by 48.7% compared to that of the untreated specimen

  10. An immersion calorimetric study of the interactions between some organic molecules and functionalized carbon nanotube surfaces

    International Nuclear Information System (INIS)

    Castillejos-López, E.; Bachiller-Baeza, B.; Guerrero-Ruiz, A.; Rodriguez-Ramos, I.

    2013-01-01

    Highlights: ► The interaction of organic chemicals with the surface of modified CNTs was studied. ► Specific π–π interactions between graphitic CNTs and toluene have been considered. ► Confinement effects in CNTs increase the adsorption strength of aromatic compounds. ► Methanol molecules form H-bonds with the oxygen functional groups on CNT surfaces. - Abstract: The interaction of organic chemicals with the surface of carbon nanotubes has been studied by immersion calorimetry revealing significant differences in the properties when these materials are modified thermally or chemically. Therefore, multiwall carbon nanotubes have been synthesized using a chemical vapour deposition procedure and subsequently aliquots were treated with HNO 3 at reflux, maintaining the reaction during different times, in order to incorporate oxygen surface groups, or were treated at 2873 K under inert atmosphere. The aim of this thermal treatment is to eliminate structural defects of the carbon nanostructures and to graphitize the amorphous carbon phases. These features were confirmed by high-resolution transmission electron microscopy. The immersion in organic compounds, including toluene, methanol and methylcyclohexane, of all these carbon nanotubes samples reveals that the surface properties are remarkably modified. Thus, the formation of different types of interaction, depending on the surface, gives place to changes in the immersion enthalpies

  11. Calcium carbonate solubility: a reappraisal of scale formation and inhibition.

    Science.gov (United States)

    Gal, J Y; Bollinger, J C; Tolosa, H; Gache, N

    1996-09-01

    Considerable disparity exists in the published thermodynamic data for selected species in the Ca(2+) /CO(2)/H(2)O system near 25 degrees C and 1 atm pressure. Some authors doubt the significance of CaCO(3)(0)aq) complexes although there is experimental evidence of their occurrence. Evaluation of all the published experimental and estimated data for aqueous calcium carbonate species confirms that the consistent set of constants given by Plummer and Busenberg in 1982 is the best available, and suggests a formation constant log beta = 3.22 for CaCO(3)(0)(aq). This value was confirmed by additional experimental data and calculations using a specially developed computer program. The solubility s and solubility product K(s) are critically evaluated for each solid polymorph (amorphous CaCO(3), ikaite, vaterite, aragonite and calcite) using a hydrated ion pair model and we give coherent explanations for the calcium carbonate precipitation/dissolution process and the existence of supersaturated waters. The practical cases of scale formation and its inhibition by phosphonate-type compounds are discussed and explained with the same model, taking into account the CaCO(3)(0)(aq) species.

  12. Hydrogeological aspects of radioactive waste disposal into surface formations

    International Nuclear Information System (INIS)

    Dlouhy, Z.

    1980-01-01

    Safe disposal is discussed of radioactive wastes in geological surface formations and basic criteria are shown of the radiological protection of population from possible effects of radioactive materials diffused in the environment. Main principles are listed governing the selection of suitable localities with respect to possible interactions of the locality and the storage site with the environment. (author)

  13. Studying Antarctic Ordinary Chondrite (OC) and Miller Range (MIL) Nakhlite Meteorites to Assess Carbonate Formation on Earth and Mars

    Science.gov (United States)

    Evans, Michael Ellis

    Carbonates are found in meteorites collected from Antarctica. The stable isotope composition of these carbonates records their formation environment on either Earth or Mars. The first research objective of this dissertation is to characterize the delta18O and delta 13C values of terrestrial carbonates formed on Ordinary Chondrites (OCs) collected in regions near known martian meteorites. The second objective is to characterize the delta18O and delta13C values of martian carbonates from Nakhlites collected from the Miller Range (MIL). The third objective is to assess environmental changes on Mars since the Noachian period. The OCs selected had no pre-terrestrial carbonates so any carbonates detected are presumed terrestrial in origin. The study methodology is stepped extraction of CO2 created from phosphoric acid reaction with meteorite carbonate. Stable isotope results show that two distinct terrestrial carbonate species (Ca-rich and Fe/Mg-rich) formed in Antarctica on OCs from a thin-film of meltwater containing dissolved CO2. Carbon isotope data suggests the terrestrial carbonates formed in equilibrium with atmospheric CO2 delta 13C = -7.5‰ at >15°C. The wide variation in delta 18O suggests the carbonates did not form in equilibrium with meteoric water alone, but possibly formed from an exchange of oxygen isotopes in both water and dissolved CO2. Antarctica provides a model for carbonate formation in a low water/rock ratio, near 0°C environment like modern Mars. Nakhlite parent basalt formed on Mars 1.3 billion years ago and the meteorites were ejected by a single impact approximately 11 million years ago. They traveled thru space before eventually falling to the Earth surface 10,000-40,000 years ago. Nakhlite samples for this research were all collected from the Miller Range (MIL) in Antarctica. The Nakhlite stable isotope results show two carbonate species (Ca-rich and Fe/Mg-rich) with a range of delta18O values that are similar to the terrestrial OC

  14. Chemically immobilised carbon nanotubes on silicon: Stable surfaces for aqueous electrochemistry

    International Nuclear Information System (INIS)

    Flavel, Benjamin S.; Garrett, David J.; Lehr, Joshua; Shapter, Joseph G.; Downard, Alison J.

    2010-01-01

    Diazonium ion chemistry has been used to electrochemically graft aminophenyl layers onto p-type silicon (1 0 0) substrates. A condensation reaction was used to immobilise single-walled carbon nanotubes with high carboxylic acid functionality directly to this layer. Electrochemical monitoring of the aminophenyl groups confirmed the formation of an amide linkage between the single-walled carbon nanotubes and the aminophenyl layer. The carbon nanotube electrode showed high stability and good electrochemical performance in aqueous solution. At moderate scan rates the Ru(NH 3 ) 6 +3/+2 couple exhibited quasi-reversible electron transfer kinetics with a standard heterogenous rate constant of 1.2 x 10 -3 cm s -1 at the covalently-linked carbon nanotube surface. The electrode thus combines the advantages of a silicon substrate for easy integration into sophisticated electrical and electronic devices, carbon nanotubes for desirable electrochemical properties, and stability in aqueous medium for future applications in environmental sensing.

  15. Formation of monofunctional cisplatin-DNA adducts in carbonate buffer.

    Science.gov (United States)

    Binter, Alexandra; Goodisman, Jerry; Dabrowiak, James C

    2006-07-01

    Carbonate in its various forms is an important component in blood and the cytosol. Since, under conditions that simulate therapy, carbonate reacts with cisplatin to form carbonato complexes, one of which is taken up and/or modified by the cell [C.R. Centerwall, J. Goodisman, D.J. Kerwood, J. Am. Chem. Soc., 127 (2005) 12768-12769], cisplatin-carbonato complexes may be important in the mechanism of action of cisplatin. In this report we study the binding of cisplatin to pBR322 DNA in two different buffers, using gel electrophoresis. In 23.8mM HEPES, N-(2-hydroxyethyl)-piperazine-N'-2-ethanesulfonic acid, 5mM NaCl, pH 7.4 buffer, cisplatin produces aquated species, which react with DNA to unwind supercoiled Form I DNA, increasing its mobility, and reducing the binding of ethidium to DNA. This behavior is consistent with the formation of the well-known intrastrand crosslink on DNA. In 23.8mM carbonate buffer, 5mM NaCl, pH 7.4, cisplatin forms carbonato species that produce DNA-adducts which do not significantly change supercoiling but enhance binding of ethidium to DNA. This behavior is consistent with the formation of a monofunctional cisplatin adduct on DNA. These results show that aquated cisplatin and carbonato complexes of cisplatin produce different types of lesions on DNA and they underscore the importance of carrying out binding studies with cisplatin and DNA using conditions that approximate those found in the cell.

  16. Surface modification of microfibrous materials with nanostructured carbon

    Energy Technology Data Exchange (ETDEWEB)

    Krasnikova, Irina V., E-mail: tokareva@catalysis.ru [Boreskov Institute of Catalysis SB RAS, pr. Ac. Lavrentieva, 5, Novosibirsk 630090 (Russian Federation); National Research Tomsk Polytechnic University, Lenin av., 30, Tomsk 634050 (Russian Federation); Mishakov, Ilya V.; Vedyagin, Aleksey A. [Boreskov Institute of Catalysis SB RAS, pr. Ac. Lavrentieva, 5, Novosibirsk 630090 (Russian Federation); National Research Tomsk Polytechnic University, Lenin av., 30, Tomsk 634050 (Russian Federation); Bauman, Yury I. [Boreskov Institute of Catalysis SB RAS, pr. Ac. Lavrentieva, 5, Novosibirsk 630090 (Russian Federation); Korneev, Denis V. [State Research Center of Virology and Biotechnology VECTOR, Koltsovo, Novosibirsk Region 630559 (Russian Federation)

    2017-01-15

    The surface of fiberglass cloth, carbon and basalt microfibers was modified with carbon nanostructured coating via catalytic chemical vapor deposition (CCVD) of 1,2-dichloroethane. Incipient wetness impregnation and solution combustion synthesis (SCS) methods were used to deposit nickel catalyst on the surface of microfibrous support. Prepared NiO/support samples were characterized by X-ray diffraction analysis and temperature-programmed reduction. The samples of resulted hybrid materials were studied by means of scanning and transmission electron microscopies as well as by low-temperature nitrogen adsorption. The nature of the support was found to have considerable effect on the CCVD process peculiarities. High yield of nanostructured carbon with largest average diameter of nanofibers within the studied series was observed when carbon microfibers were used as a support. This sample characterized with moderate surface area (about 80 m{sup 2}/g after 2 h of CCVD) shows the best anchorage effect. Among the mineral supports, fiberglass tissue was found to provide highest carbon yield (up to 3.07 g/g{sub FG}) and surface area (up to 344 m{sup 2}/g) due to applicability of SCS method for Ni deposition. - Highlights: • The microfibers of different nature were coated with nanostructured carbon layer. • Features of CNF growth and characteristics of hybrid materials were studied. • Appropriate anchorage of CNF layer on microfiber’s surface was demonstrated.

  17. Following the Interstellar History of Carbon: From the Interiors of Stars to the Surfaces of Planets.

    Science.gov (United States)

    Ziurys, L M; Halfen, D T; Geppert, W; Aikawa, Y

    2016-12-01

    The chemical history of carbon is traced from its origin in stellar nucleosynthesis to its delivery to planet surfaces. The molecular carriers of this element are examined at each stage in the cycling of interstellar organic material and their eventual incorporation into solar system bodies. The connection between the various interstellar carbon reservoirs is also examined. Carbon has two stellar sources: supernova explosions and mass loss from evolved stars. In the latter case, the carbon is dredged up from the interior and then ejected into a circumstellar envelope, where a rich and unusual C-based chemistry occurs. This molecular material is eventually released into the general interstellar medium through planetary nebulae. It is first incorporated into diffuse clouds, where carbon is found in polyatomic molecules such as H 2 CO, HCN, HNC, c-C 3 H 2 , and even C 60 + . These objects then collapse into dense clouds, the sites of star and planet formation. Such clouds foster an active organic chemistry, producing compounds with a wide range of functional groups with both gas-phase and surface mechanisms. As stars and planets form, the chemical composition is altered by increasing stellar radiation, as well as possibly by reactions in the presolar nebula. Some molecular, carbon-rich material remains pristine, however, encapsulated in comets, meteorites, and interplanetary dust particles, and is delivered to planet surfaces. Key Words: Carbon isotopes-Prebiotic evolution-Interstellar molecules-Comets-Meteorites. Astrobiology 16, 997-1012.

  18. Formation of negative ions on a metal surface

    International Nuclear Information System (INIS)

    Amersfoort, P.W. van.

    1987-01-01

    In this thesis a fundamental study of the charge exchange process of positive ions on the converter surface is presented. Beams of hydrogen ad cesium ions are scattered from a thoroughly cleaned W(110) surface, under ultra-high vacuum conditions. The cesium coverage of the surface is a controlled parameter. Ch. 2 deals with the negative-ion formation probability for hydrogen atoms. The influence of coabsorption of hydrogen is studied in Ch. 3. These measurements are important for understanding the formation process in plasma sources, because the converter surface is expected to be strongly contaminated with hydrogen. The charge state of scattered cesium particles is investigated in Ch. 4. Knowledge of this parameter is essential for Ch. 5, in which a model study of adsorption of cesium on a metal surface in contact with a plasma is presented. Finally, the negative-ion formation process in a plasma environment is studied in Ch. 6. Measurements done on a hollow-cathode discharge equipped with a novel type of converter, a porous tungsten button, are discussed. Liquid cesium diffuses through this button towards the side in contact with the plasma. (Auth.)

  19. Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

    International Nuclear Information System (INIS)

    Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M.; Sapsay, V.I.; Klymchuk, D.O.; Puziy, A.M.

    2012-01-01

    Highlights: ► Phosphoric acid activation results in formation of carbons with acidic surface groups. ► Maximum amount of surface groups is introduced at impregnation ratio 1.25. ► Phosphoric acid activated carbons show high capacity to copper. ► Phosphoric acid activated carbons are predominantly microporous. ► Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 °C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S BET = 2081 m 2 /g, V tot = 1.1 cm 3 /g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0–2.6), weakly acidic carboxylic (pK = 4.7–5.0), enol/lactone (pK = 6.7–7.4; 8.8–9.4) and phenol (pK = 10.1–10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

  20. Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

    Energy Technology Data Exchange (ETDEWEB)

    Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M. [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine); Sapsay, V.I.; Klymchuk, D.O. [M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, 2 Tereshchenkivska St., 01601 Kyiv (Ukraine); Puziy, A.M., E-mail: alexander.puziy@ispe.kiev.ua [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Phosphoric acid activation results in formation of carbons with acidic surface groups. Black-Right-Pointing-Pointer Maximum amount of surface groups is introduced at impregnation ratio 1.25. Black-Right-Pointing-Pointer Phosphoric acid activated carbons show high capacity to copper. Black-Right-Pointing-Pointer Phosphoric acid activated carbons are predominantly microporous. Black-Right-Pointing-Pointer Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 Degree-Sign C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S{sub BET} = 2081 m{sup 2}/g, V{sub tot} = 1.1 cm{sup 3}/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

  1. Release of Crude Oil from Silica and Calcium Carbonate Surfaces

    DEFF Research Database (Denmark)

    Liu, Xiaoyan; Yan, Wei; Stenby, Erling Halfdan

    2016-01-01

    Adsorption and desorption of a North Sea crude oil to silica and calcium carbonate surfaces were studied by a quartz crystal microbalance, while the bare surfaces and adsorbed oil layers were characterized by atomic force microscopy and contact angle measurements. Water contact angles were measured...

  2. Oxidation of Ethylene Carbonate on Li Metal Oxide Surfaces

    DEFF Research Database (Denmark)

    Østergaard, Thomas M.; Giordano, Livia; Castelli, Ivano Eligio

    2018-01-01

    Understanding the reactivity of the cathode surface is of key importance to the development of batteries. Here, density functional theory is applied to investigate the oxidative decomposition of the electrolyte component, ethylene carbonate (EC), on layered LixMO(2) oxide surfaces. We compare...

  3. Surface roughness effects on blister formation in polycrystalline molybdenum

    International Nuclear Information System (INIS)

    Saidoh, Masahiro; Sone, Kazuho; Yamada, Rayji; Ohtsuka, Hidewo; Murakami, Yoshio

    1977-07-01

    Polycrystalline molybdenum targets with electropolished and roughened surfaces were bombarded with 100 keV He + and 200 keV H 2 + ions at room temperature. It has been demonstrated that the blister formation is largely or completely suppressed by roughening the electropolished surface with emery paper of No. 1200, No. 400 and No. 100. Up to a He + fluence of 1.0 x 10 19 particles/cm 2 , no blisters are observed in the targets with the two roughest surfaces, while on the smooth surface blisters begin to occur at a fluence of 7.5 x 10 17 particles/cm 2 . The surface roughness effect on blister suppression is discussed in relation to the projected range of incident particles. (auth.)

  4. Electrochemical formation of carbonated corrosion products on carbon steel in deaerated solutions

    International Nuclear Information System (INIS)

    Refait, Ph.; Bourdoiseau, J.A.; Jeannin, M.; Nguyen, D.D.

    2012-01-01

    Highlights: ► Green rust is electro-generated at low NaHCO 3 concentration (0.003 mol dm −3 ). ► Chukanovite and carbonated green rust are obtained in NaHCO 3 + Na 2 SO 4 deaerated electrolytes. ► The mechanisms of formation of carbonated corrosion products of carbon steel are specified. - Abstract: To investigate the nature and properties of carbonated rust layers, carbon steel electrodes were polarised anodically at a potential ∼100–200 mV higher than the open circuit potential in NaHCO 3 solutions (0.003, 0.1 and 1 mol dm −3 ) continuously deaerated by an argon flow. X-ray diffraction and μ-Raman spectroscopy were used to identify the electro-generated compounds. GR(CO 3 2− ) (=Fe II 4 Fe III 2 (OH) 12 CO 3 ·4H 2 O) is observed at 0.003 and 0.1 mol dm −3 NaHCO 3 whereas FeCO 3 is obtained at the largest concentration (1 mol dm −3 ). GR(CO 3 2− ) is accompanied by magnetite Fe 3 O 4 at the lowest NaHCO 3 concentration. The current density decreases to negligible values in each case, indicating that a passive film also forms independently of the nature of the carbonated compound. Experiments were performed similarly in solutions of NaHCO 3 and Na 2 SO 4 . Chukanovite Fe 2 (OH) 2 CO 3 could be obtained in solutions containing 0.03 mol dm −3 of each salt. In contrast with the results obtained in the solutions free of sulphate, the current density remains important during the formation of the rust layer

  5. Water electrolysis with a conducting carbon cloth: subthreshold hydrogen generation and superthreshold carbon quantum dot formation.

    Science.gov (United States)

    Biswal, Mandakini; Deshpande, Aparna; Kelkar, Sarika; Ogale, Satishchandra

    2014-03-01

    A conducting carbon cloth, which has an interesting turbostratic microstructure and functional groups that are distinctly different from other ordered forms of carbon, such as graphite, graphene, and carbon nanotubes, was synthesized by a simple one-step pyrolysis of cellulose fabric. This turbostratic disorder and surface chemical functionalities had interesting consequences for water splitting and hydrogen generation when such a cloth was used as an electrode in the alkaline electrolysis process. Importantly, this work also gives a new twist to carbon-assisted electrolysis. During electrolysis, the active sites in the carbon cloth allow slow oxidation of its surface to transform the surface groups from COH to COOH and so forth at a voltage as low as 0.2 V in a two-electrode system, along with platinum as the cathode, instead of 1.23 V (plus overpotential), which is required for platinum, steel, or even graphite anodes. The quantity of subthreshold hydrogen evolved was 24 mL cm(-2)  h(-1) at 1 V. Interestingly, at a superthreshold potential (>1.23 V+overpotential), another remarkable phenomenon was found. At such voltages, along with the high rate and quantity of hydrogen evolution, rapid exfoliation of the tiny nanoscale (5-7 nm) units of carbon quantum dots (CQDs) are found in copious amounts due to an enhanced oxidation rate. These CQDs show bright-blue fluorescence under UV light. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Influence of surface chemistry on inkjet printed carbon nanotube films

    International Nuclear Information System (INIS)

    Hopkins, Alan R.; Straw, David C.; Spurrell, Kathryn C.

    2011-01-01

    Carbon nanotube ink chemistry and the proper formulation are crucial for direct-write printing of nanotubes. Moreover, the correct surface chemistry of the self-assembled monolayers that assist the direct deposition of carbon nanotubes onto the substrate is equally important to preserve orientation of the printed carbon nanotubes. We report that the successful formulation of two single walled carbon nanotube (SWNT) inks yields a consistent, homogenous printing pattern possessing the requisite viscosities needed for flow through the microcapillary nozzles of the inkjet printer with fairly modest drying times. The addition of an aqueous sodium silicate allows for a reliable method for forming a uniform carbon nanotube network deposited directly onto unfunctionalized surfaces such as glass or quartz via inkjet deposition. Furthermore, this sodium silicate ingredient helps preserve applied orientation to the printed SWNT solution. Sheet resistivity of this carbon nanotube ink formula printed on quartz decreases as a function of passes and is independent of the substrate. SWNTs were successfully patterned on Au. This amine-based surface chemistry dramatically helps improve the isolation stabilization of the printed SWNTs as seen in the atomic force microscopy (AFM) image. Lastly, using our optimized SWNT ink formula and waveform parameters in the Fuji materials printer, we are able to directly write/print SWNTs into 2D patterns. Dried ink pattern expose and help orient roped carbon nanotubes that are suspended in ordered arrays across the cracks.

  7. Plasma cleaning and the removal of carbon from metal surfaces

    International Nuclear Information System (INIS)

    Baker, M.A.

    1980-01-01

    In an investigation of the plasma cleaning of metals and the plasma etching of carbon, a mass spectrometer was used as a sensitive process monitor. CO 2 produced by the plasma oxidation of carbon films or of organic contamination and occluded carbon at the surfaces of metals proved to be the most suitable gas to monitor. A good correlation was obtained between the measured etch rate of carbon and the resulting CO 2 partial pressure monitored continuously with the mass spectrometer. The rate of etching of carbon in an oxygen-argon plasma at 0.1 Torr was high when the carbon was at cathode potential and low when it was electrically isolated in the plasma, thus confirming the findings of previous workers and indicating the importance of ion bombardment in the etching process. Superficial organic contamination on the surfaces of the metals aluminium and copper and of the alloy Inconel 625 was quickly removed by the oxygen-argon plasma when the metal was electrically isolated and also when it was at cathode potential. Occluded carbon (or carbides) at or near the surfaces of the metals was removed slowly and only when the metal was at cathode potential, thus illustrating again the importance of ion bombardment. (Auth.)

  8. Surface plasma functionalization influences macrophage behavior on carbon nanowalls

    Energy Technology Data Exchange (ETDEWEB)

    Ion, Raluca [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Vizireanu, Sorin [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Stancu, Claudia Elena [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Luculescu, Catalin [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Cimpean, Anisoara, E-mail: anisoara.cimpean@bio.unibuc.ro [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Dinescu, Gheorghe [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania)

    2015-03-01

    The surfaces of carbon nanowall samples as scaffolds for tissue engineering applications were treated with oxygen or nitrogen plasma to improve their wettability and to functionalize their surfaces with different functional groups. X-ray photoelectron spectroscopy and water contact angle results illustrated the effective conversion of the carbon nanowall surfaces from hydrophobic to hydrophilic and the incorporation of various amounts of carbon, oxygen and nitrogen functional groups during the treatments. The early inflammatory responses elicited by un-treated and modified carbon nanowall surfaces were investigated by quantifying tumor necrosis factor-alpha and macrophage inflammatory protein-1 alpha released by attached RAW 264.7 macrophage cells. Scanning electron microscopy and fluorescence studies were employed to investigate the changes in macrophage morphology and adhesive properties, while MTT assay was used to quantify cell proliferation. All samples sustained macrophage adhesion and growth. In addition, nitrogen plasma treatment was more beneficial for cell adhesion in comparison with un-modified carbon nanowall surfaces. Instead, oxygen plasma functionalization led to increased macrophage adhesion and spreading suggesting a more activated phenotype, confirmed by elevated cytokine release. Thus, our findings showed that the chemical surface alterations which occur as a result of plasma treatment, independent of surface wettability, affect macrophage response in vitro. - Highlights: • N{sub 2} and O{sub 2} plasma treatments alter the CNW surface chemistry and wettability. • Cells seeded on CNW scaffolds are viable and metabolically active. • Surface functional groups, independent of surface wettability, affect cell response. • O{sub 2} plasma treatment of CNW leads to a more activated macrophage phenotype.

  9. Brown carbon formation from ketoaldehydes of biogenic monoterpenes

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Tran B.; Laskin, Alexander; Laskin, Julia; Nizkorodov, Sergey

    2013-04-10

    Sources and chemical composition of the brown carbon are poorly understood, and even less is known about the mechanisms of its atmospheric transformations. This work presents molecular level investigation of the reactive compound ketolimononaldehyde (KLA, C9H14O3), a second generation ozonolysis product of limonene (C10H16), as a potent brown carbon precursor in secondary organic aerosol (SOA) through its reactions with reduced nitrogen compounds such as ammonium ion (NH4+), ammonia, and amino acids. The reactions of synthesized and purified KLA with NH4+ and glycine resulted in the formation of chromophores nearly identical in spectral properties and formation rates to those found in similarly-aged limonene/O3 SOA. Similar chemical reaction processes of limononaldehyde (LA, C10H16O2) and pinonaldehyde (PA, C10H16O2), the first-generation ozonolysis products in the oxidation of limonene and α-pinene, respectively, were also studied, but the resulting products did not exhibit light absorption properties of brown carbon, suggesting that the unique molecular structure of KLA produces visible-light-absorbing compounds. The KLA/NH4+ and KLA/GLY reactions produce water-soluble, hydrolysis-resilient chromophores with high mass absorption coefficients (MAC = 2000-4000 cm2 g-1) at λ ~ 500 nm, precisely at the maximum of the solar emission spectrum. Liquid chromatography was used to isolate the light-absorbing fraction, and UV-Vis, FTIR, NMR and high-resolution mass spectrometry (HR-MS) techniques were used to investigate the structures and chemical properties of the light-absorbing compounds. The KLA browning reaction generates a diverse mixture of light-absorbing compounds, with the majority of the observable products containing 1-4 units of KLA and 0-2 nitrogen atoms. Based on the HR-MS product distribution, conjugated aldol condensates, secondary imines (Schiff bases), and N-heterocycles like pyrroles may contribute in varying degree to the light-absorbing properties

  10. Surface plasmon observed for carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Bursill, L A; Stadelmann, P A [Ecole Polytechnique Federale, Lausanne (Switzerland); Peng, J L; Prawer, S [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1994-12-31

    This paper presents parallel electron energy loss spectra (PEELS) results, obtained for individual carbon nanotubes, using nanoprobe techniques (1-2 nm diameter electron beam), energy resolution 0.5 eV and collection times of 4-25 sec. The aim was to use a nanoprobe to compare PEELS spectra from different parts of a tube, in order to search for variations in sp{sup 2}/sp{sup 3} bonding ratios as well as to look for orientation dependent plasmon and core-loss phenomena. It also seemed interesting to compare results for nanotubes with those for other varieties of graphitized carbons. The most interesting result so far was the appearance of a 15 eV plasmon peak, which appeared only for tubes containing {<=} about 12 graphite-like layers. This peak did not shift significantly with tube size. A low-loss peaks at 6 eV of variable relative intensity was also observed this peak was relatively very weak for amorphous tubes; it appears to be characteristic of graphite-like layers, as found for nanotubes and, of course, graphite itself. This paper is restricted to discussion of the low-loss results. The experimental techniques are first described, including some details of the methods which may be used to disperse and support sooty carbons for high-resolution transmission electron microscopy. The results are then presented, followed by an interpretation of all the low-loss PEELS results, including those of the other authors. 14 refs., 2 figs.

  11. CARBON SEQUESTRATION ON SURFACE MINE LANDS

    Energy Technology Data Exchange (ETDEWEB)

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2005-06-22

    An area planted in 2004 on Bent Mountain in Pike County was shifted to the Department of Energy project to centralize an area to become a demonstration site. An additional 98.3 acres were planted on Peabody lands in western Kentucky and Bent Mountain to bring the total area under study by this project to 556.5 acres as indicated in Table 2. Major efforts this quarter include the implementation of new plots that will examine the influence of differing geologic material on tree growth and survival, water quality and quantity and carbon sequestration. Normal monitoring and maintenance was conducted and additional instrumentation was installed to monitor the new areas planted.

  12. Formation of the self-assembled structures by the ultrasonic cavitation erosion-corrosion effect on carbon steel

    Directory of Open Access Journals (Sweden)

    Dayun Yan

    2015-11-01

    Full Text Available The cavitation erosion-corrosion effect on the metal surface always forms irregular oxide structures. In this study, we reported the formation of regular self-assembled structures of amorphous nanoparticles around the cavitation erosion pits on carbon steel upon the ultrasonic cavitation in methylene blue solution. Each self-assembled structure was composed of linearly aligned nanoparticles of about 100 nm. The formation of self-assembled structures might be due to the combined effect of corrosion, specific sonochemical reaction in methylene blue solution, and the magnetic domain structures on the carbon steel.

  13. Highly reversible lead-carbon battery anode with lead grafting on the carbon surface

    KAUST Repository

    Yin, Jian; Lin, Nan; Zhang, Wenli; Lin, Zheqi; Zhang, Ziqing; Wang, Yue; Shi, Jun; Bao, Jinpeng; Lin, Haibo

    2018-01-01

    A novel C/Pb composite has been successfully prepared by electroless plating to reduce the hydrogen evolution and achieve the high reversibility of the anode of lead-carbon battery (LCB). The deposited lead on the surface of C/Pb composite was found to be uniform and adherent to carbon surface. Because lead has been stuck on the surface of C/Pb composite, the embedded structure suppresses the hydrogen evolution of lead-carbon anode and strengthens the connection between carbon additive and sponge lead. Compared with the blank anode, the lead-carbon anode with C/Pb composite displays excellent charge–discharge reversibility, which is attributed to the good connection between carbon additives and lead that has been stuck on the surface of C/Pb composite during the preparation process. The addition of C/Pb composite maintains a solid anode structure with high specific surface area and power volume, and thereby, it plays a significant role in the highly reversible lead-carbon anode.

  14. Highly reversible lead-carbon battery anode with lead grafting on the carbon surface

    KAUST Repository

    Yin, Jian

    2018-03-27

    A novel C/Pb composite has been successfully prepared by electroless plating to reduce the hydrogen evolution and achieve the high reversibility of the anode of lead-carbon battery (LCB). The deposited lead on the surface of C/Pb composite was found to be uniform and adherent to carbon surface. Because lead has been stuck on the surface of C/Pb composite, the embedded structure suppresses the hydrogen evolution of lead-carbon anode and strengthens the connection between carbon additive and sponge lead. Compared with the blank anode, the lead-carbon anode with C/Pb composite displays excellent charge–discharge reversibility, which is attributed to the good connection between carbon additives and lead that has been stuck on the surface of C/Pb composite during the preparation process. The addition of C/Pb composite maintains a solid anode structure with high specific surface area and power volume, and thereby, it plays a significant role in the highly reversible lead-carbon anode.

  15. El Paso Formation - a Lower Ordovician platform carbonate deposit

    Energy Technology Data Exchange (ETDEWEB)

    Clemons, R.E.

    1987-05-01

    The eastward-transgressive Lower Ordovician El Paso Formation conformably overlies Bliss Sandstone in southern New Mexico. Locally, lower El Paso was deposited on low hills of plutonic and volcanic rocks. The region subsided gradually throughout Canadian time, receiving the El Paso carbonate rock blanket up to 460 m thick. Lithologic and chronologic correlative rocks were deposited over most of the southwestern US as the first Paleozoic carbonate platform sequence. The El Paso Formation contains four members, listed here in ascending order: Hitt Canyon, Jose, McKelligon, and Padre. Gradually decreasing sand content upward through the Hitt Canyon indicates deepening water and/or greater distance to shore. Girvanella(.) oncolites are locally abundant. Stromatolite mounds near the top of the Hitt Canyon, combined with an influx of sand, ooids, and rounded bioclasts in the Jose Member, recorded a shoaling phase. The overlying McKelligon Member contains little or no sand, and sponge-Calathium mounds are prominent at some locales. Stromatolite mounds are interbedded with sponge-Calathium mounds in a few sections. Lower Padre Member beds are typically silty to sandy and locally contain thinly-laminated zones. The Padre contains more restricted fauna that includes traces of ostracods. Pervasive bioturbation of El Paso beds and fauna consisting of echinoderms, sponges, gastropods, trilobites, Nuia, Calathium, cephalopods, and algae plus minor brachiopods and Pulchrilamina indicate predominating shallow-subtidal environments. Low-energy platform environments, in which a large volume of micritic muds accumulated, were disturbed thousands of times by storms producing abundant thin, poorly washed biosparite, intrasparite, and intrasparrudite lenses.

  16. Shewanella putrefaciens Adhesion and Biofilm Formation on Food Processing Surfaces

    Science.gov (United States)

    Bagge, Dorthe; Hjelm, Mette; Johansen, Charlotte; Huber, Ingrid; Gram, Lone

    2001-01-01

    Laboratory model systems were developed for studying Shewanella putrefaciens adhesion and biofilm formation under batch and flow conditions. S. putrefaciens plays a major role in food spoilage and may cause microbially induced corrosion on steel surfaces. S. putrefaciens bacteria suspended in buffer adhered readily to stainless steel surfaces. Maximum numbers of adherent bacteria per square centimeter were reached in 8 h at 25°C and reflected the cell density in suspension. Numbers of adhering bacteria from a suspension containing 108 CFU/ml were much lower in a laminar flow system (modified Robbins device) (reaching 102 CFU/cm2) than in a batch system (reaching 107 CFU/cm2), and maximum numbers were reached after 24 h. When nutrients were supplied, S. putrefaciens grew in biofilms with layers of bacteria. The rate of biofilm formation and the thickness of the film were not dependent on the availability of carbohydrate (lactate or glucose) or on iron starvation. The number of S. putrefaciens bacteria on the surface was partly influenced by the presence of other bacteria (Pseudomonas fluorescens) which reduced the numbers of S. putrefaciens bacteria in the biofilm. Numbers of bacteria on the surface must be quantified to evaluate the influence of environmental factors on adhesion and biofilm formation. We used a combination of fluorescence microscopy (4′,6′-diamidino-2-phenylindole staining and in situ hybridization, for mixed-culture studies), ultrasonic removal of bacteria from surfaces, and indirect conductometry and found this combination sufficient to quantify bacteria on surfaces. PMID:11319118

  17. Surface Ligand Promotion of Carbon Dioxide Reduction through Stabilizing Chemisorbed Reactive Intermediates.

    Science.gov (United States)

    Wang, Zhijiang; Wu, Lina; Sun, Kun; Chen, Ting; Jiang, Zhaohua; Cheng, Tao; Goddard, William A

    2018-05-23

    We have explored functionalizing metal catalysts with surface ligands as an approach to facilitate electrochemical carbon dioxide reduction reaction (CO 2 RR). To provide a molecular level understanding of the mechanism by which this enhancement occurs, we combine in situ spectroscopy analysis with an interpretation based on quantum mechanics (QM) calculations. We find that a surface ligand can play a critical role in stabilizing the chemisorbed CO 2 , which facilitates CO 2 activation and leads to a 0.3 V decrease in the overpotential for carbon monoxide (CO) formation. Moreover, the presence of the surface ligand leads to nearly exclusive CO production. At -0.6 V (versus reversible hydrogen electrode, RHE), CO is the only significant product with a faradic efficiency of 93% and a current density of 1.9 mA cm -2 . This improvement corresponds to 53-fold enhancement in turnover frequency compared with the Ag nanoparticles (NPs) without surface ligands.

  18. Synergistic methane formation kinetics for hydrogen impact on carbon

    International Nuclear Information System (INIS)

    Haasz, A.A.; Davis, J.W.

    1986-06-01

    A physical/chemical model is presented for the reaction kinetics for methane formation from carbon, due to bombardment by energetic (∼ 100's eV) H + ions and thermal (∼ 1 eV) H 0 atoms. While the model was developed for H + and H 0 , it can be readily applied to non-hydrogenic energetic particles (ions or atoms, e.g., Ar + , He + , He) in combination with thermal (∼ 1 eV) hydrogen (again ions or atoms) impacting on carbon. Both collisional (in the case of the energetic particles) and chemical reaction processes are included. Special cases of sub-eV H 0 alone, energetic H + alone and combined H 0 plus H + were considered and fitted to experimental data. Generally good agreement was found between theoretical predictions and experimental results over the experimental flux and H + energy ranges studied (H 0 flux: 6x10 14 - 7x10 15 H 0 /cm 2 s, H + flux: 6x10 12 - 5x10 15 H + /cm 2 s, H + energy: 300 eV/H + and 1 keV/H + )

  19. Chlorine effect on the formation of carbon nanofibers.

    Science.gov (United States)

    Lin, Wang-Hua; Takahashi, Yusuke; Li, Yuan-Yao; Sakoda, Akiyoshi

    2012-12-01

    Platelet graphite nanofibers (GNFs) and turbostratic carbon nanofibers (CNFs) are synthesized by the thermal evaporation and decomposition of a polymer-based mixture at 700 degrees C using Ni as a catalyst. The mixture consists of poly(ethylene glycol) (PEG), serving as the carbon source, and hydrochloric acid solution (HCl(aq)), serving as the promoter/additive for the growth of CNFs. High-purity zigzag-shaped platelet GNFs form with 10 wt% HCl(aq) as an additive in the PEG. The diameters of the platelet GNFs are in the range of 40-60 nm, with lengths of a few micrometers. High-resolution transmission electron microscopy images indicate a high degree of graphitization and well ordered graphene layers along the fiber axis. In contrast, high-purity turbostratic CNFs form with 20 wt% HCl(aq) in the PEG. The diameter and length of the turbostratic CNFs are 20-40 nm and a few micrometers, respectively. The participation of HCl in the thermal process leads to the formation of Ni-Cl compounds. The amount of chlorine affects the shape of the Ni catalyst, which determines the type of CNF formed.

  20. An investigation of the functional groups on the surface of activated carbons

    Directory of Open Access Journals (Sweden)

    MARYTE DERVINYTE

    2004-05-01

    Full Text Available Activated carbons were produced in the laboratory from wood using a 20-run Plackett–Burman experimental design for 19 factors. The obtained batches of activated carbon were analysed by potentiometric titration and FTIR spectroscopy to determine the surface functional groups. The results obtained by potentiometric titration displayed the distribution of individual acidity constants of those groups in the pK range. Considering this parameter, the surface functional groups were divided into carboxyl, lactone and phenol. The linear regression equations reflecting the influence of each operation used for the synthesis on the amount of these functional groups in the obtained activated carbons were generated. The FTIR spectra were used in parallel for the evaluation of the amount and the type of the surface functional groups. Relationships between the two data sets obtained by potentiometric titration and FTIR spectroscopy were evaluated by correlation analysis. It was established that the amount of surface functional groups determined by potentiometric titration positively correlates with the intensity of the peaks of hydrophilic functional groups in the FTIR spectra. At the same time, the negative correlation between potentiometrically determined amount of surface functional groups and the intensity of peaks of hydrophobic functional groups was observed. Most probably, these non-polar formations can take part in the interaction of carbon surface with H+/OH- ions and diminish the strength of existent functional groups.

  1. Evaluation of scale formation in waterwall heated surfaces

    Directory of Open Access Journals (Sweden)

    Taylasheva Tatiana

    2017-01-01

    Full Text Available This paper presents the possibility of forecasting assessments of the speed and the time of formation of depositions in the evaporator-tube elements of double-drum boilers. The values of thermal flow in the wall region of tank screens of boiler furnace are obtained, besides the velocity values of scaling metal corrosion products are obtained. Conclusions about the ability of forecasting unnominal situations and emergency risks dependent with damage to the screen surface heating pipes are made.

  2. Microstructure and surface properties of lignocellulosic-based activated carbons

    Science.gov (United States)

    González-García, P.; Centeno, T. A.; Urones-Garrote, E.; Ávila-Brande, D.; Otero-Díaz, L. C.

    2013-01-01

    Low cost activated carbons have been produced via chemical activation, by using KOH at 700 °C, from the bamboo species Guadua Angustifolia and Bambusa Vulgaris Striata and the residues from shells of the fruits of Castanea Sativa and Juglans Regia as carbon precursors. The scanning electron microscopy micrographs show the conservation of the precursor shape in the case of the Guadua Angustifolia and Bambusa Vulgaris Striata activated carbons. Transmission electron microscopy analyses reveal that these materials consist of carbon platelet-like particles with variable length and thickness, formed by highly disordered graphene-like layers with sp2 content ≈ 95% and average mass density of 1.65 g/cm3 (25% below standard graphite). Textural parameters indicate a high porosity development with surface areas ranging from 850 to 1100 m2/g and average pore width centered in the supermicropores range (1.3-1.8 nm). The electrochemical performance of the activated carbons shows specific capacitance values at low current density (1 mA/cm2) as high as 161 F/g in the Juglans Regia activated carbon, as a result of its textural parameters and the presence of pseudocapacitance derived from surface oxygenated acidic groups (mainly quinones and ethers) identified in this activated carbon.

  3. Bacterial biofilm formation in different surfaces of food industries

    Directory of Open Access Journals (Sweden)

    Karine Angélica Dalla Costa

    2017-06-01

    Full Text Available The term biofilm describes the sessile microbial life form, characterized by microorganism adhesion to any surface and with the production of extracellular polymeric substances. In food industries, the formation of biofilms results in serious problems, since it can be a contamination source of the food product, compromising the final product quality and consumer health. The aim of this study was to verify the adhesion of biofilms (sessile cells of pathogenic and/or deteriorating bacteria against surfaces of the food industry. The bacterial species tested were Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, Listeria monocytogenes ATCC 19117 and Salmonella Typhimurium ATCC 14028. It was used stainless steel and polypropylene coupons as contact surfaces. The results demonstrated that P. aeruginosa and S. Typhimurium showed higher biofilm formation capacity. Statistically, there was no difference in count of P. aeruginosa and S. Typhimurium (p > 0.05 cells. The same occurred between L. monocytogenes and S. aureus. However, the counts of P. aeruginosa and S. Typhimurium cells were statistically higher than S. aureus and L. monocytogenes (p < 0.05. By means of scanning electron microscopy it was also found increased adhesion of P. aeruginosa. The results revealed that P. aeruginosa was the bacterial species with higher biofilm formation capacity among the others.

  4. CARBON SEQUESTRATION ON SURFACE MINE LANDS

    Energy Technology Data Exchange (ETDEWEB)

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2005-02-25

    The October-December Quarter was dedicated to analyzing the first two years tree planting activities and evaluation of the results. This included the analyses of the species success at each of the sites and quantifying the data for future year determination of research levels. Additional detailed studies have been planned to further quantify total carbon storage accumulation on the research areas. At least 124 acres of new plantings will be established in 2005 to bring the total to 500 acres or more in the study area across the state of Kentucky. During the first 2 years of activities, 172,000 tree seedlings were planted on 257 acres in eastern Kentucky and 77,520 seedlings were planted on 119 acres in western Kentucky. The quantities of each species was discussed in the first Annual Report. A monitoring program was implemented to measure treatment effects on above and below ground C and nitrogen (N) pools and fluxes. A sampling strategy was devised that will allow for statistical comparisons of the various species within planting conditions and sites. Seedling heights and diameters are measured for initial status and re-measured on an annual basis. Leaves were harvested and leaf area measurements were performed. They were then dried and weighed and analyzed for C and N. Whole trees were removed to determine biomass levels and to evaluate C and N levels in all components of the trees. Clip plots were taken to determine herbaceous production and litter was collected in baskets and gathered each month to quantify C & N levels. Soil samples were collected to determine the chemical and mineralogical characterization of each area. The physical attributes of the soils are also being determined to provide information on the relative level of compaction. Hydrology and water quality monitoring is being conducted on all areas. Weather data is also being recorded that measures precipitation values, temperature, relative humidity wind speed and direction and solar radiation

  5. Anti-parallel dimer and tetramer formation of propylene carbonate

    Directory of Open Access Journals (Sweden)

    Ayana Tagawa

    2017-09-01

    Full Text Available Raman scattering and infrared (IR absorption spectra of enantiopure (R-propylene carbonate ((RPC and racemic propylene carbonate (PC were recorded at room temperature, 25 °C, in benzene (Bz solution and in the pure liquid state to investigate the presence of dimers and other higher order intermolecular associations. (RPC and PC both demonstrated a strong C=O stretching vibrational band. The band exhibited changes in its shape and resonance wavenumber highly dependent on the concentrations of PCs, whereas a difference between the chirality of (RPC and PC had little influence. In an extremely dilute condition, doubly split bands were observed at 1807 and 1820 cm-1 in both Raman and IR spectra, which are assigned to the characteristic bands of isolated monomeric PCs. An additional band appeared at 1795 cm-1 in a dilute to concentrated regime, and its magnitude strengthened with increasing concentrations accompanied with slight increasing in the magnitude of 1807 cm-1 band in Raman spectra, while an increase in the magnitude of 1807 cm-1 band was clearly greater than that of 1795 cm-1 band in IR spectra. The spectrum changes at 1795 and 1807 cm-1 were attributed to characteristics of anti-parallel dimer formation of PCs caused by strong dipole-dipole interactions between C=O groups. Moreover, another additional signal was clearly observed at 1780-1790 cm-1 in a concentrated regime, and became the primary signal in the pure liquid state with slight increasing in the intensity of 1795 cm-1 band in Raman spectra. On the other hand, in IR spectra the observed increasing of 1780-1790 cm-1 band was much less than that of 1795 cm-1 band. These newly found spectrum changes in the concentrated regime are attributed to the formation of anti-parallel tetramers of PCs based on the characteristics of band selection rule found in Raman and IR spectra. Equilibrium constants for the anti-parallel dimer (KD and tetramer formation (KT of PCs in Bz solution and in

  6. Surface Quality of Staggered PCD End Mill in Milling of Carbon Fiber Reinforced Plastics

    Directory of Open Access Journals (Sweden)

    Guangjun Liu

    2017-02-01

    Full Text Available Machined surface quality determines the reliability, wear resistance and service life of carbon fiber reinforced plastic (CFRP workpieces. In this work, the formation mechanism of the surface topography and the machining defects of CFRPs are proposed, and the influence of milling parameters and fiber cutting angles on the surface quality of CFRPs is obtained, which can provide a reference for extended tool life and good surface quality. Trimming and slot milling tests of unidirectional CFRP laminates are performed. The surface roughness of the machined surface is measured, and the influence of milling parameters on the surface roughness is analyzed. A regression model for the surface roughness of CFRP milling is established. A significance test of the regression model is conducted. The machined surface topography of milling CFRP unidirectional laminates with different fiber orientations is analyzed, and the effect of fiber cutting angle on the surface topography of the machined surface is presented by using a digital super depth-of-field microscope and scanning electron microscope (SEM. To study the influence of fiber cutting angle on machining defects, the machined topography under different fiber orientations is analyzed. The slot milling defects and their formation mechanism under different fiber cutting angles are investigated.

  7. Bulk and Surface Aqueous Speciation of Calcite: Implications for Low-Salinity Waterflooding of Carbonate Reservoirs

    KAUST Repository

    Yutkin, Maxim P.

    2017-08-25

    calcite bulk and surface equilibria draws several important inferences about the proposed LSW oil-recovery mechanisms. Diffuse double-layer expansion (DLE) is impossible for brine ionic strength greater than 0.1 molar. Because of rapid rock/brine equilibration, the dissolution mechanism for releasing adhered oil is eliminated. Also, fines mobilization and concomitant oil release cannot occur because there are few loose fines and clays in a majority of carbonates. LSW cannot be a low-interfacial-tension alkaline flood because carbonate dissolution exhausts all injected base near the wellbore and lowers pH to that set by the rock and by formation CO2. In spite of diffuse double-layer collapse in carbonate reservoirs, surface ion-exchange oil release remains feasible, but unproved.

  8. Swarm formation control utilizing elliptical surfaces and limiting functions.

    Science.gov (United States)

    Barnes, Laura E; Fields, Mary Anne; Valavanis, Kimon P

    2009-12-01

    In this paper, we present a strategy for organizing swarms of unmanned vehicles into a formation by utilizing artificial potential fields that were generated from normal and sigmoid functions. These functions construct the surface on which swarm members travel, controlling the overall swarm geometry and the individual member spacing. Nonlinear limiting functions are defined to provide tighter swarm control by modifying and adjusting a set of control variables that force the swarm to behave according to set constraints, formation, and member spacing. The artificial potential functions and limiting functions are combined to control swarm formation, orientation, and swarm movement as a whole. Parameters are chosen based on desired formation and user-defined constraints. This approach is computationally efficient and scales well to different swarm sizes, to heterogeneous systems, and to both centralized and decentralized swarm models. Simulation results are presented for a swarm of 10 and 40 robots that follow circle, ellipse, and wedge formations. Experimental results are included to demonstrate the applicability of the approach on a swarm of four custom-built unmanned ground vehicles (UGVs).

  9. Hydrogenation of surface carbon on alumina-supported nickel

    Energy Technology Data Exchange (ETDEWEB)

    Mccarthy, J.G.; Wise, H.

    1979-05-01

    The methanation of carbon deposited by CO or ethylene decomposition on Girdler G-65 catalyst (25Vertical Bar3< nickel, 8Vertical Bar3< alkali, mostly CaO, 4Vertical Bar3< C as graphite, on alumina) was studied by temperature-programed desorption and temperature-programed surface reaction. Four types of carbon were identified: ..cap alpha..-carbon consisted of isolated carbon atoms bonded to nickel and reacting with hydrogen at 470/sup 0/ +/- 20/sup 0/K; ..gamma..-carbon was probably a bulk carbide, most likely Ni/sub 3/C, which had a reaction peak at 550/sup 0/K; ..beta..-carbon consisted of amorphous, polymerized carbon, which had a reaction peak at 680/sup 0/K; and an unreactive crystalline graphite-like species. The ..cap alpha..-form was thermally unstable and transformed into the ..beta..-form above 600/sup 0/K. Both ..cap alpha..- and ..beta..-forms slowly converted to inert graphite above 600/sup 0/K. The evidence suggested that synthesis gas methanation proceeds by dissociative adsorption of CO as the rate-determining step which forms a very reactive carbon adatom state (..cap alpha..') which converts to the ..cap alpha..-state in the absence of hydrogen and to methane in the presence of hydrogen.

  10. Effect of alloying on carbon formation during ethane dehydrogenation

    DEFF Research Database (Denmark)

    Rovik, Anne; Kegnæs, Søren; Dahl, Søren

    2009-01-01

    The structure sensitivity of different transition metals in the hydrogenolysis, dehydrogenation, and coking reactions during ethane conversion has been investigated. The investigated metals, Ni, Ru, Rh, and Pd, are co-impregnated with Ag onto an inactive MgAl2O4 spinel support and tested in the c......The structure sensitivity of different transition metals in the hydrogenolysis, dehydrogenation, and coking reactions during ethane conversion has been investigated. The investigated metals, Ni, Ru, Rh, and Pd, are co-impregnated with Ag onto an inactive MgAl2O4 spinel support and tested...... in the conversion of ethane. A tendency is clear for all catalysts: In the first period of time 100% ethane is converted and roughly half of the carbon is converted into coke and deposited on the catalyst. The other half of the carbon is converted into methane. The active sites in the hydrogenolysis are blocked...... by coke during the initial period where after dehydrogenation of ethane is observed. It has previously been predicted in surface science studies that Ag covers the steps of certain transition metals. Here it is documented that the hydrogenolysis and coking reactions are significantly suppressed by co...

  11. Reduction in Surface Ocean Carbon Storage across the Middle Miocene

    Science.gov (United States)

    Babila, T. L.; Sosdian, S. M.; Foster, G. L.; Lear, C. H.

    2017-12-01

    During the Middle Miocene, Earth underwent a profound climate shift from the warmth of the Miocene Climatic Optimum (MCO; 14-17 Ma) to the stable icehouse of today during the Middle Miocene Climate transition (MMCT). Elevated atmospheric carbon dioxide concentrations (pCO2) revealed by boron isotope records (δ11B) link massive volcanic outputs of Columbia River Flood Basalts to the general warmth of MCO. Superimposed on the long-term cooling trend (MMCT) is a gradual pCO2 decline and numerous positive carbon isotope (δ13C) excursions that indicate dynamic variations in the global carbon cycle. Enhanced organic carbon burial via marine productivity, increased silicate weathering and volcanic emission cessation are each invoked to explain the drawdown of pCO2. To better constrain the oceanic role in carbon sequestration over the Middle Miocene detailed records of carbonate chemistry are needed. We present high resolution Boron/Calcium (B/Ca) and δ13C records in planktonic foraminifer T.trilobus spanning 12-17 Ma at ODP 761 (tropical eastern Indian Ocean) to document changes in surface ocean carbonate chemistry. An overall 30% increase in B/Ca ratios is expressed as two stepwise phases occurring at 14.7 and 13 Ma. Cyclic B/Ca variations are coherent with complimentary δ13C records suggesting a tight coupling between ocean carbonate chemistry parameters. Lower resolution B/Ca data at DSDP 588 (Pacific) and ODP 926 (Atlantic) corroborate the trends observed at ODP 761. We employ a paired approach that combines B/Ca (this study) to δ11B (Foster et al., 2012) and an ad hoc calibration to estimate changes in surface ocean dissolved inorganic carbon (DIC). We estimate a substantial decrease in surface ocean DIC spanning the Middle Miocene that culminates with modern day like values. This gradual decline in surface ocean DIC is coeval with existing deep-ocean records which together suggests a whole ocean reduction in carbon storage. We speculate that enhanced weathering

  12. Microstructure and surface properties of lignocellulosic-based activated carbons

    International Nuclear Information System (INIS)

    González-García, P.; Centeno, T.A.; Urones-Garrote, E.; Ávila-Brande, D.; Otero-Díaz, L.C.

    2013-01-01

    Highlights: ► Activated carbons were produced by KOH activation at 700 °C. ► The observed nanostructure consists of highly disordered graphene–like layers with sp 2 bond content ≈ 95%. ► Textural parameters show high surface area (≈ 1000 m 2 /g) and pore width of 1.3–1.8 nm. ► Specific capacitance reaches values as high as 161 F/g. - Abstract: Low cost activated carbons have been produced via chemical activation, by using KOH at 700 °C, from the bamboo species Guadua Angustifolia and Bambusa Vulgaris Striata and the residues from shells of the fruits of Castanea Sativa and Juglans Regia as carbon precursors. The scanning electron microscopy micrographs show the conservation of the precursor shape in the case of the Guadua Angustifolia and Bambusa Vulgaris Striata activated carbons. Transmission electron microscopy analyses reveal that these materials consist of carbon platelet–like particles with variable length and thickness, formed by highly disordered graphene–like layers with sp 2 content ≈ 95% and average mass density of 1.65 g/cm 3 (25% below standard graphite). Textural parameters indicate a high porosity development with surface areas ranging from 850 to 1100 m 2 /g and average pore width centered in the supermicropores range (1.3–1.8 nm). The electrochemical performance of the activated carbons shows specific capacitance values at low current density (1 mA/cm 2 ) as high as 161 F/g in the Juglans Regia activated carbon, as a result of its textural parameters and the presence of pseudocapacitance derived from surface oxygenated acidic groups (mainly quinones and ethers) identified in this activated carbon.

  13. Thermographic analysis of plasma facing components covered by carbon surface layer in tokamaks

    International Nuclear Information System (INIS)

    Gardarein, Jean-Laurent

    2007-01-01

    Tokamaks are reactors based on the thermonuclear fusion energy with magnetic confinement of the plasma. In theses machines, several MW are coupled to the plasma for about 10 s. A large part of this power is directed towards plasma facing components (PFC). For better understanding and control the heat flux transfer from the plasma to the surrounding wall, it is very important to measure the surface temperature of the PFC and to estimate the imposed heat flux. In most of tokamaks using carbon PFC, the eroded carbon is circulating in the plasma and redeposited elsewhere. During the plasma operations, this leads at some locations to the formation of thin or thick carbon layers usually poorly attached to the PFC. These surface layers with unknown thermal properties complicate the calculation of the heat flux from IR surface temperature measurements. To solve this problem, we develop first, inverse method to estimate the heat flux using thermocouple (not sensitive to the carbon surface layers) temperature measurements. Then, we propose a front face pulsed photothermal method allowing an estimation of layers thermal diffusivity, conductivity, effusivity and the thermal contact resistance between the layer and the tile. The principle is to study with an infrared sensor, the cooling of the layer surface after heating by a short laser pulse, this cooling depending on the thermal properties of the successive layers. (author) [fr

  14. Natural variability in the surface ocean carbonate ion concentration

    OpenAIRE

    N. S. Lovenduski; M. C. Long; K. Lindsay

    2015-01-01

    We investigate variability in the surface ocean carbonate ion concentration ([CO32−]) on the basis of a long control simulation with a fully-coupled Earth System Model. The simulation is run with a prescribed, pre-industrial atmospheric CO2 concentration for 1000 years, permitting investigation of natural [CO32−] variability on interannual to multi-decadal timescales. We find high interannual variability in surface [CO32−] in the tropical...

  15. Natural variability in the surface ocean carbonate ion concentration

    OpenAIRE

    Lovenduski, N. S.; Long, M. C.; Lindsay, K.

    2015-01-01

    We investigate variability in the surface ocean carbonate ion concentration ([CO32−]) on the basis of a~long control simulation with an Earth System Model. The simulation is run with a prescribed, pre-industrial atmospheric CO2 concentration for 1000 years, permitting investigation of natural [CO32−] variability on interannual to multi-decadal timescales. We find high interannual variability in surface [CO32−] in the tropical Pacific and ...

  16. Functionalized Surface Geometries Induce: “Bone: Formation by Autoinduction”

    Directory of Open Access Journals (Sweden)

    Ugo Ripamonti

    2018-02-01

    Full Text Available The induction of tissue formation, and the allied disciplines of tissue engineering and regenerative medicine, have flooded the twenty-first century tissue biology scenario and morphed into high expectations of a fulfilling regenerative dream of molecularly generated tissues and organs in assembling human tissue factories. The grand conceptualization of deploying soluble molecular signals, first defined by Turing as forms generating substances, or morphogens, stemmed from classic last century studies that hypothesized the presence of morphogens in several mineralized and non-mineralized mammalian matrices. The realization of morphogens within mammalian matrices devised dissociative extractions and chromatographic procedures to isolate, purify, and finally reconstitute the cloned morphogens, found to be members of the transforming growth factor-β (TGF-β supergene family, with insoluble signals or substrata to induce de novo tissue induction and morphogenesis. Can we however construct macroporous bioreactors per se capable of inducing bone formation even without the exogenous applications of the osteogenic soluble molecular signals of the TGF-β supergene family? This review describes original research on coral-derived calcium phosphate-based macroporous constructs showing that the formation of bone is independent of the exogenous application of the osteogenic soluble signals of the TGF-β supergene family. Such signals are the molecular bases of the induction of bone formation. The aim of this review is to primarily describe today's hottest topic of biomaterials' science, i.e., to construct and define osteogenetic biomaterials' surfaces that per se, in its own right, do initiate the induction of bone formation. Biomaterials are often used to reconstruct osseous defects particularly in the craniofacial skeleton. Edentulism did spring titanium implants as tooth replacement strategies. No were else that titanium surfaces require functionalized

  17. Antiseptics and microcosm biofilm formation on titanium surfaces

    Directory of Open Access Journals (Sweden)

    Georgia VERARDI

    2016-01-01

    Full Text Available Abstract Oral rehabilitation with osseointegrated implants is a way to restore esthetics and masticatory function in edentulous patients, but bacterial colonization around the implants may lead to mucositis or peri-implantitis and consequent implant loss. Peri-implantitis is the main complication of oral rehabilitation with dental implants and, therefore, it is necessary to take into account the potential effects of antiseptics such as chlorhexidine (CHX, chloramine T (CHT, triclosan (TRI, and essential oils (EO on bacterial adhesion and on biofilm formation. To assess the action of these substances, we used the microcosm technique, in which the oral environment and periodontal conditions are simulated in vitro on titanium discs with different surface treatments (smooth surface - SS, acid-etched smooth surface - AESS, sand-blasted surface - SBS, and sand-blasted and acid-etched surface - SBAES. Roughness measurements yielded the following results: SS: 0.47 µm, AESS: 0.43 µm, SB: 0.79 µm, and SBAES: 0.72 µm. There was statistical difference only between SBS and AESS. There was no statistical difference among antiseptic treatments. However, EO and CHT showed lower bacterial counts compared with the saline solution treatment (control group. Thus, the current gold standard (CHX did not outperform CHT and EO, which were efficient in reducing the biofilm biomass compared with saline solution.

  18. In-situ determination of amine/epoxy and carboxylic/epoxy exothermic heat of reaction on surface of modified carbon nanotubes and structural verification of covalent bond formation

    Science.gov (United States)

    Neves, Juliana C.; de Castro, Vinícius G.; Assis, Ana L. S.; Veiga, Amanda G.; Rocco, Maria Luiza M.; Silva, Glaura G.

    2018-04-01

    An effective nanofiller-matrix interaction is considered crucial to produce enhanced nanocomposites. Nevertheless, there is lack of experiments focused in the direct measurement of possible filler-matrix covalent linkage, which was the main goal of this work for a carbon nanotube (CNT)/epoxy system. CNT were functionalized with oxygenated (ox) functions and further with triethylenetetramine (TETA). An in-situ determination methodology of epoxy-CNTs heat of reaction was developed by Differential Scanning Calorimetry (DSC). Values of -(8.7 ± 0.4) and -(6.0 ± 0.6) J/g were observed for epoxy with CNT-ox and CNT-TETA, respectively. These results confirm the occurrence of covalent bonds for both functionalized CNTs, a very important information due to the literature generally disregard this possibility for oxygenated functions. The higher value obtained for CNT-ox can be attributed to a not complete amidation and to steric impediments in the CNT-TETA structure. The modified CNTs produced by DSC experiments were then characterized by X-Ray Photoelectron Spectroscopy, Transmission Electron Microscopy and Thermogravimetry, which confirmed the covalent linkage. This characterization methodology can be used to verify the occurrence of covalent bonds in various nanocomposites with a quantitative evaluation, providing data for better understanding of the role of CNT functional groups and for tailoring its interface with polymers.

  19. XPS analysis of the carbon fibers surface modified via HMDSO to carbon nanotube growth

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, L.D.R.; Gomes, M.C.B.; Trava-Airoldi, V.J.; Corat, E.J.; Lugo, D.C. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil)

    2016-07-01

    Full text: Carbon fibers (CF) have been widely used to reinforce structural composites. Due to their strength-to-weight properties, CF composites are finding increased structural uses in areas such as aerospace, aeronautical, automobile and others. The strength of the fiber-resin interface bond has been found to be the limiting factor to the mechanical properties of CF-epoxy materials, due to their non-polar nature that limit the affinity of CF to bind chemically to any matrix. The growth of carbon nanotubes (CNTs) on the surface of CF is a promising approach for improving mechanical, electrical and thermal properties of structural composites. However growing CNTs on CF presents some obstacles, such as diffusion of metal catalyst particles on CF, uneven CNT growth and loss of mechanical properties of CF. To avoid the diffusion of catalyst particles we modified the CF surface with hexamethyldisiloxane (HMDSO) at low temperature (400 °C), also preventing the loss of mechanical properties and allowing uniform CNTs growth. We deposited CNTs via floating catalyst method, with ferrocene providing the catalyst particle and the oxidative dehydrogenation reaction of acetylene providing the carbon. The CF surface modification was analyzed via X-ray photoelectron spectroscopy (XPS) and CNTs growth via scanning electron microscopy with field emission gun. The XPS analysis showed that HMDSO promotes the binding of oxygen to carbon and silicon present on CF surface, the chemical modification of the surface of the CF enables the uniform growth of carbon nanotubes. (author)

  20. XPS analysis of the carbon fibers surface modified via HMDSO to carbon nanotube growth

    International Nuclear Information System (INIS)

    Cardoso, L.D.R.; Gomes, M.C.B.; Trava-Airoldi, V.J.; Corat, E.J.; Lugo, D.C.

    2016-01-01

    Full text: Carbon fibers (CF) have been widely used to reinforce structural composites. Due to their strength-to-weight properties, CF composites are finding increased structural uses in areas such as aerospace, aeronautical, automobile and others. The strength of the fiber-resin interface bond has been found to be the limiting factor to the mechanical properties of CF-epoxy materials, due to their non-polar nature that limit the affinity of CF to bind chemically to any matrix. The growth of carbon nanotubes (CNTs) on the surface of CF is a promising approach for improving mechanical, electrical and thermal properties of structural composites. However growing CNTs on CF presents some obstacles, such as diffusion of metal catalyst particles on CF, uneven CNT growth and loss of mechanical properties of CF. To avoid the diffusion of catalyst particles we modified the CF surface with hexamethyldisiloxane (HMDSO) at low temperature (400 °C), also preventing the loss of mechanical properties and allowing uniform CNTs growth. We deposited CNTs via floating catalyst method, with ferrocene providing the catalyst particle and the oxidative dehydrogenation reaction of acetylene providing the carbon. The CF surface modification was analyzed via X-ray photoelectron spectroscopy (XPS) and CNTs growth via scanning electron microscopy with field emission gun. The XPS analysis showed that HMDSO promotes the binding of oxygen to carbon and silicon present on CF surface, the chemical modification of the surface of the CF enables the uniform growth of carbon nanotubes. (author)

  1. [Formation of microbial populations on the surface of protective coatings].

    Science.gov (United States)

    Kopteva, Zh P; Zanina, V V; Piliashenko-Novokhatnyĭ, A I; Kopteva, A E; Kozlova, I A

    2001-01-01

    Formation of microbial cenosis on the surface of polyethylene-, polyurethane- and oil-bitumen-based protective coatings was studied in dynamics during 1, 3, 7, 14 and 21 days. It has been shown that the biofilm was formed on the protective materials during 14 days and consisted of ammonifying, denitrifying, hydrocarbon-oxidizing and sulphate-reducing bacteria referred to Pseudomonas, Arthrobacter, Bacillus and Kesulfovibrio genera. The bacteria which form the biofilm on coatings possess high denitrifying and sulphate-reducing activities. Corrosion inhibitors-biocydes, introduced in composition of oil-bitumen coatings suppressed growth and metabolic activity of corrosion-active bacteria.

  2. Formation of nanocrystalline TiC from titanium and different carbon sources by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Jia Haoling [Key Lab of Liquid Structure and Heredity of Materials, Jingshi Road 73, Jinan 250061, Shandong (China); Zhang Zhonghua [Key Lab of Liquid Structure and Heredity of Materials, Jingshi Road 73, Jinan 250061, Shandong (China)], E-mail: zh_zhang@sdu.edu.cn; Qi Zhen [Key Lab of Liquid Structure and Heredity of Materials, Jingshi Road 73, Jinan 250061, Shandong (China); Liu Guodong [School of Materials Science and Engineering, Shandong University, Jingshi Road 73, Jinan 250061 (China); Bian Xiufang [Key Lab of Liquid Structure and Heredity of Materials, Jingshi Road 73, Jinan 250061, Shandong (China)

    2009-03-20

    In this paper, the formation of nanocrystalline TiC from titanium powders and different carbon resources by mechanical alloying (MA) has been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental results show that nanocrystalline TiC can be synthesized from Ti powders and different carbon resources (activated carbon, carbon fibres or carbon nanotubes) by MA at room temperature. Titanium and different carbon resources have a significant effect on the Ti-C reaction and the formation of TiC during MA. Moreover, the formation of nanocrystalline TiC is governed by a gradual diffusion reaction mechanism during MA, regardless of different carbon resources.

  3. Grafting the surface of carbon nanotubes and carbon black with the chemical properties of hyperbranched polyamines

    Science.gov (United States)

    Morales-Lara, Francisco; Domingo-García, María; López-Garzón, Rafael; Luz Godino-Salido, María; Peñas-Sanjuán, Antonio; López-Garzón, F. Javier; Pérez-Mendoza, Manuel; Melguizo, Manuel

    2016-01-01

    Controlling the chemistry on the surface of new carbon materials is a key factor to widen the range of their applicability. In this paper we show a grafting methodology of polyalkylamines to the surface of carbon nanomaterials, in particular, carbon nanotubes and a carbon black. The aim of this work is to reach large degrees of covalent functionalization with hyperbranched polyethyleneimines (HBPEIs) and to efficiently preserve the strong chelating properties of the HBPEIs when they are fixed to the surface of these carbon materials. This functionalization opens new possibilities of using these carbon nanotubes-based hybrids. The results show that the HBPEIs are covalently attached to the carbon materials, forming hybrids. These hybrids emerge from the reaction of amine functions of the HBPEIs with carbonyls and carboxylic anhydrides of the carbon surface which become imine and imide bonds. Thus, due to the nature of these bonds, the pre-oxidized samples with relevant number of C=O groups showed an increase in the degree of functionalization with the HBPEIs. Furthermore, both the acid-base properties and the coordination capacity for metal ions of the hybrids are equivalent to that of the free HBPEIs in solution. This means that the chemical characteristics of the HBPEIs have been efficiently transferred to the hybrids. To reach this conclusion we have developed a novel procedure to assess the acid-base and the coordination properties of the hybrids (solids) by means of potentiometric titration. The good agreement of the values obtained for the hybrids and for the free HBPEIs in aqueous solution supports the reliability of the procedure. Moreover, the high capacity of the hybrids to capture Ni2+ by complexation opens new possibilities of using these hybrids to capture high-value metal ions such as Pd2+ and Pt2+.

  4. The effect of surface modification on initial ice formation on aluminum surfaces

    DEFF Research Database (Denmark)

    Rahimi, Maral; Afshari, Alireza; Fojan, Peter

    2015-01-01

    material of heat exchanger fins is aluminum, this paper focuses on the effect of aluminum wettability on the initial stages of ice formation. The ice growth was studied on bare as well as hydrophilically and hydrophobically modified surfaces of aluminum (8011A) sheets, commonly used in heat exchangers...

  5. Carbon surface diffusion and SiC nanocluster self-ordering

    International Nuclear Information System (INIS)

    Pezoldt, J.; Trushin, Yu.V.; Kharlamov, V.S.; Schmidt, A.A.; Cimalla, V.; Ambacher, O.

    2006-01-01

    The process of the spatial ordering of SiC nanoclusters on the step edges on Si surfaces was studied by means of multi-scale computer simulation. The evolution of cluster arrays on an ideal flat surface and surfaces with terraces of various widths was performed by kinetic Monte Carlo (KMC) simulations based on quantitative studies of potential energy surfaces (PES) by molecular dynamics (MD). PES analysis revealed that certain types of steps act as strong trapping centres for both Si and C adatoms stimulating clusters nucleation. Spatial ordering of the SiC nanoclusters at the terrace edges can be achieved if the parameters of the growth process (substrate temperature, carbon flux) and substrate (steps direction and terrace widths) are adjusted to the surface morphology. Temperature ranges for growth regimes with and without formation of cluster chains were determined. Cluster size distributions and the dependence of optimal terrace width for self ordering on the deposition parameters were obtained

  6. Adhesion enhancement of Al coatings on carbon/epoxy composite surfaces by atmospheric plasma

    International Nuclear Information System (INIS)

    Coulon, J.F.; Tournerie, N.; Maillard, H.

    2013-01-01

    Adhesion strengths between aluminium thin film coatings and manufactured carbon/epoxy composite surfaces were measured by assessing fracture tensile strengths using pull-off tests. The effect of the substrate roughness (nm to μm) of these composite surfaces on adhesion was studied by examining the surface free energies and adhesion strengths. The adhesion strengths of the coatings varied significantly. To improve the coating adhesion, each composite surface was treated with atmospheric plasma prior to deposition, which resulted in an increase in the surface free energy from approximately 40 mJ/m 2 to 70 mJ/m 2 because the plasma pretreatment led to the formation of hydrophilic C-O and C=O bonds on the composite surfaces, as demonstrated by X-ray photoelectron spectroscopy analyses. The adhesion strengths of the coatings were enhanced for all surface roughnesses studied. In our study, the effect of mechanical adhesion due to roughness was separated from the effect of modifying the chemical bonds with plasma activation. The adhesion ability of the pure resin was relatively weak. Increasing the surface roughness largely improved the adhesion of the resin surface. Plasma treatment of the pure resin also increased the surface adhesion. Our study shows that plasma activation effectively enhances the adhesion of manufactured composites, even when the surface roughness is on the order of microns. The ageing of the surface activation was also investigated, and the results demonstrate that atmospheric plasma has potential for use in the pretreatment of composite materials.

  7. Surface proteins and the formation of biofilms by Staphylococcus aureus.

    Science.gov (United States)

    Kim, Sung Joon; Chang, James; Rimal, Binayak; Yang, Hao; Schaefer, Jacob

    2018-03-01

    Staphylococcus aureus biofilms pose a serious clinical threat as reservoirs for persistent infections. Despite this clinical significance, the composition and mechanism of formation of S. aureus biofilms are unknown. To address these problems, we used solid-state NMR to examine S. aureus (SA113), a strong biofilm-forming strain. We labeled whole cells and cell walls of planktonic cells, young biofilms formed for 12-24h after stationary phase, and more mature biofilms formed for up to 60h after stationary phase. All samples were labeled either by (i) [ 15 N]glycine and l-[1- 13 C]threonine, or in separate experiments, by (ii) l-[2- 13 C, 15 N]leucine. We then measured 13 C- 15 N direct bonds by C{N} rotational-echo double resonance (REDOR). The increase in peptidoglycan stems that have bridges connected to a surface protein was determined directly by a cell-wall double difference (biofilm REDOR difference minus planktonic REDOR difference). This procedure eliminates errors arising from differences in 15 N isotopic enrichments and from the routing of 13 C label from threonine degradation to glycine. For both planktonic cells and the mature biofilm, 20% of pentaglycyl bridges are not cross-linked and are potential surface-protein attachment sites. None of these sites has a surface protein attached in the planktonic cells, but one-fourth have a surface protein attached in the mature biofilm. Moreover, the leucine-label shows that the concentration of β-strands in leucine-rich regions doubles in the mature biofilm. Thus, a primary event in establishing a S. aureus biofilm is extensive decoration of the cell surface with surface proteins that are linked covalently to the cell wall and promote cell-cell adhesion. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Effects of Surface Treatment of Activated Carbon on Its Surface and Cr(VI) Adsorption Characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soo Jin; Jang, Yu Sin [Advanced Materials Division., Korea Research Institute of Chimical Technology, Taejon (Korea)

    2001-04-01

    In this work, the effect of surface treatments on activated carbons (ACs) has been studied in the context of gas and liquid adsorption behaviors. The chemical solutions used in this experiment were 35% sodium hydroxide, and these were used for the acidic and basic treatments, respectively. The surface properties have been determined by pH, acid-base values, and FT-IR. The adsorption isotherms of Cr(VI) ion on activated carbons have been studied with the 5 mg/l concentration at ambient temperature. N{sub 2} adsorption isotherm characteristics, which include the specific surface area, micro pore volume, and microporosity, were determined by BET and Boer's-plot methods. In case of the acidic treatment of activated carbons, it was observed that the adsorption of Cr(VI) ion was more effective due to the increase acid value (or acidic functional group) of activated carbon surfaces. However, the basic treatment on activated carbons was caused no significant effects, probably due to the decreased specific surface area and total pore volume. 27 refs., 7 figs., 4 tabs.

  9. Mechanism behind the formation of self-assembled nano-sized clusters in diamond-like carbon nanocomposite.

    Science.gov (United States)

    Foong, Yuan Mei; Koh, Angel Ting Ting; Niu, Lifang; Chua, Daniel Hock Chuan

    2011-12-01

    Many studies have shown that Diamond-like carbon (DLC) films with diversified material properties are obtainable through doping process but the presence of the dopants were reported to form independent nanoclusters within the carbon matrix. Using combined analysis from theoretical estimations (Saha's equation and coefficient of absorption, alpha(p)), Transport of Ions In Matter (TRIM) simulation and experimental results, this work examined the mechanism behind the formation of self-assembled nanoclusters in DLC nanocomposite. We showed that the presence of metal dopants increased the heat dissipation on DLC, which allowed the energetic metal species to diffuse and enhance the formation of nanoclusters that increased the surface roughness of the films. In addition, TRIM and X-ray Photoelectron Spectroscopy (XPS) hinted the presence of energetic species may force the carbon ions to react with the interface to form silicon carbide bonds, which may be a more dominant factor compared to internal stress reduction in improving the adhesion strength of DLC.

  10. Near surface silicide formation after off-normal Fe-implantation of Si(001) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Khanbabaee, B., E-mail: khanbabaee@physik.uni-siegen.de; Pietsch, U. [Solid State Physics, University of Siegen, D-57068 Siegen (Germany); Lützenkirchen-Hecht, D. [Fachbereich C - Physik, Bergische Universität Wuppertal, D-42097 Wuppertal (Germany); Hübner, R.; Grenzer, J.; Facsko, S. [Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden (Germany)

    2014-07-14

    We report on formation of non-crystalline Fe-silicides of various stoichiometries below the amorphized surface of crystalline Si(001) after irradiation with 5 keV Fe{sup +} ions under off-normal incidence. We examined samples prepared with ion fluences of 0.1 × 10{sup 17} and 5 × 10{sup 17} ions cm{sup −2} exhibiting a flat and patterned surface morphology, respectively. Whereas the iron silicides are found across the whole surface of the flat sample, they are concentrated at the top of ridges at the rippled surface. A depth resolved analysis of the chemical states of Si and Fe atoms in the near surface region was performed by combining X-ray photoelectron spectroscopy and X-ray absorption spectroscopy (XAS) using synchrotron radiation. The chemical shift and the line shape of the Si 2p core levels and valence bands were measured and associated with the formation of silicide bonds of different stoichiometric composition changing from an Fe-rich silicides (Fe{sub 3}Si) close to the surface into a Si-rich silicide (FeSi{sub 2}) towards the inner interface to the Si(001) substrate. This finding is supported by XAS analysis at the Fe K-edge which shows changes of the chemical environment and the near order atomic coordination of the Fe atoms in the region close to surface. Because a similar Fe depth profile has been found for samples co-sputtered with Fe during Kr{sup +} ion irradiation, our results suggest the importance of chemically bonded Fe in the surface region for the process of ripple formation.

  11. Understanding carbon nanotube channel formation in the lipid membrane

    Science.gov (United States)

    Choi, Moon-ki; Kim, Hyunki; Lee, Byung Ho; Kim, Teayeop; Rho, Junsuk; Kim, Moon Ki; Kim, Kyunghoon

    2018-03-01

    Carbon nanotubes (CNTs) have been considered a prominent nano-channel in cell membranes because of their prominent ion-conductance and ion-selectivity, offering agents for a biomimetic channel platform. Using a coarse-grained molecular dynamics simulation, we clarify a construction mechanism of vertical CNT nano-channels in a lipid membrane for a long period, which has been difficult to observe in previous CNT-lipid interaction simulations. The result shows that both the lipid coating density and length of CNT affect the suitable fabrication condition for a vertical and stable CNT channel. Also, simulation elucidated that a lipid coating on the surface of the CNT prevents the CNT from burrowing into the lipid membrane and the vertical channel is stabilized by the repulsion force between the lipids in the coating and membrane. Our study provides an essential understanding of how CNTs can form stable and vertical channels in the membrane, which is important for designing new types of artificial channels as biosensors for bio-fluidic studies.

  12. Surface grafted chitosan gels. Part II. Gel formation and characterization

    DEFF Research Database (Denmark)

    Liu, Chao; Thormann, Esben; Claesson, Per M.

    2014-01-01

    Responsive biomaterial hydrogels attract significant attention due to their biocompatibility and degradability. In order to make chitosan based gels, we first graft one layer of chitosan to silica, and then build a chitosan/poly(acrylic acid) multilayer using the layer-by-layer approach. After...... cross-linking the chitosan present in the polyelectrolyte multilayer, poly(acrylic acid) is partly removed by exposing the multilayer structure to a concentrated carbonate buffer solution at a high pH, leaving a surface-grafted cross-linked gel. Chemical cross-linking enhances the gel stability against...... detachment and decomposition. The chemical reaction between gluteraldehyde, the cross-linking agent, and chitosan was followed in situ using total internal reflection Raman (TIRR) spectroscopy, which provided a molecular insight into the complex reaction mechanism, as well as the means to quantify the cross...

  13. Role of Streptococcus mutans surface proteins for biofilm formation

    Directory of Open Access Journals (Sweden)

    Michiyo Matsumoto-Nakano

    2018-02-01

    Full Text Available Summary: Streptococcus mutans has been implicated as a primary causative agent of dental caries in humans. An important virulence property of the bacterium is its ability to form biofilm known as dental plaque on tooth surfaces. In addition, this organism also produces glucosyltransferases, multiple glucan-binding proteins, protein antigen c, and collagen-binding protein, surface proteins that coordinate to produce dental plaque, thus inducing dental caries. Bacteria utilize quorum-sensing systems to modulate environmental stress responses. A major mechanism of response to signals is represented by the so called two-component signal transduction system, which enables bacteria to regulate their gene expression and coordinate activities in response to environmental stress. As for S. mutans, a signal peptide-mediated quorum-sensing system encoded by comCDE has been found to be a regulatory system that responds to cell density and certain environmental stresses by excreting a peptide signal molecule termed CSP (competence-stimulating peptide. One of its principal virulence factors is production of bacteriocins (peptide antibiotics referred to as mutacins. Two-component signal transduction systems are commonly utilized by bacteria to regulate bacteriocin gene expression and are also related to biofilm formation by S. mutans. Keywords: Streptococcus mutans, Surface proteins, Biofilm, Signal transduction

  14. Formation of nanocrystalline surface layers in various metallic materials by near surface severe plastic deformation

    Directory of Open Access Journals (Sweden)

    Masahide Sato, Nobuhiro Tsuji, Yoritoshi Minamino and Yuichiro Koizumi

    2004-01-01

    Full Text Available The surface of the various kinds of metallic materials sheets were severely deformed by wire-brushing at ambient temperature to achieve nanocrystalline surface layer. The surface layers of the metallic materials developed by the near surface severe plastic deformation (NS-SPD were characterized by means of TEM. Nearly equiaxed nanocrystals with grain sizes ranging from 30 to 200 nm were observed in the near surface regions of all the severely scratched metallic materials, which are Ti-added ultra-low carbon interstitial free steel, austenitic stainless steel (SUS304, 99.99 wt.%Al, commercial purity aluminum (A1050 and A1100, Al–Mg alloy (A5083, Al-4 wt.%Cu alloy, OFHC-Cu (C1020, Cu–Zn alloy (C2600 and Pb-1.5%Sn alloy. In case of the 1050-H24 aluminum, the depth of the surface nanocrystalline layer was about 15 μm. It was clarified that wire-brushing is an effective way of NS-SPD, and surface nanocrystallization can be easily achieved in most of metallic materials.

  15. Adventitious Carbon on Primary Sample Containment Metal Surfaces

    Science.gov (United States)

    Calaway, M. J.; Fries, M. D.

    2015-01-01

    Future missions that return astromaterials with trace carbonaceous signatures will require strict protocols for reducing and controlling terrestrial carbon contamination. Adventitious carbon (AC) on primary sample containers and related hardware is an important source of that contamination. AC is a thin film layer or heterogeneously dispersed carbonaceous material that naturally accrues from the environment on the surface of atmospheric exposed metal parts. To test basic cleaning techniques for AC control, metal surfaces commonly used for flight hardware and curating astromaterials at JSC were cleaned using a basic cleaning protocol and characterized for AC residue. Two electropolished stainless steel 316L (SS- 316L) and two Al 6061 (Al-6061) test coupons (2.5 cm diameter by 0.3 cm thick) were subjected to precision cleaning in the JSC Genesis ISO class 4 cleanroom Precision Cleaning Laboratory. Afterwards, the samples were analyzed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy.

  16. Friction Properties of Surface-Fluorinated Carbon Nanotubes

    Science.gov (United States)

    Wal, R. L. Vander; Miyoshi, K.; Street, K. W.; Tomasek, A. J.; Peng, H.; Liu, Y.; Margrave, J. L.; Khabashesku, V. N.

    2005-01-01

    Surface modification of the tubular or sphere-shaped carbon nanoparticles through chemical treatment, e.g., fluorination, is expected to significantly affect their friction properties. In this study, a direct fluorination of the graphene-built tubular (single-walled carbon nanotubes) structures has been carried out to obtain a series of fluorinated nanotubes (fluoronanotubes) with variable C(n)F (n =2-20) stoichiometries. The friction coefficients for fluoronanotubes, as well as pristine and chemically cut nanotubes, were found to reach values as low as 0.002-0.07, according to evaluation tests run in contact with sapphire in air of about 40% relative humidity on a ball-on-disk tribometer which provided an unidirectional sliding friction motion. These preliminary results demonstrate ultra-low friction properties and show a promise in applications of surface modified nanocarbons as a solid lubricant.

  17. Methane formation during deuteron bombardment of carbon in the energy range of 100 to 1500 eV

    International Nuclear Information System (INIS)

    Sone, K.

    1982-01-01

    Methane (CD 4 ) formation rates during deuteron bombardment of carbon (Papyex) have been measured in the energy range of 100 to 1500 eV. The temperature dependence of the methane formation rate is well explained by the model proposed by Erents et al. in the temperature range of 600 to 1150 K. The model, however, does not explain the dependence of the methane formation rate on the flux of incident deuterons at a certain temperature near Tsub(m) at which the formation rate has a maximum value. An alternative model is proposed in which the methane formation rate is assumed to be proportional to the product of the following three parameters: the surface concentration of deuterium atoms, the chemical reaction rate for the formation of methane, and the rate of production of vacancies on the surface by the deuteron bombardment. This model predicts an energy dependence of methane formation which has a maximum around 900 eV even at different deuteron fluxes, when the calculated result by Weissman and Sigmund is used for the surface deposited energy responsible for the production of vacancies. (author)

  18. Natural variability in the surface ocean carbonate ion concentration

    Directory of Open Access Journals (Sweden)

    N. S. Lovenduski

    2015-11-01

    Full Text Available We investigate variability in the surface ocean carbonate ion concentration ([CO32−] on the basis of a~long control simulation with an Earth System Model. The simulation is run with a prescribed, pre-industrial atmospheric CO2 concentration for 1000 years, permitting investigation of natural [CO32−] variability on interannual to multi-decadal timescales. We find high interannual variability in surface [CO32−] in the tropical Pacific and at the boundaries between the subtropical and subpolar gyres in the Northern Hemisphere, and relatively low interannual variability in the centers of the subtropical gyres and in the Southern Ocean. Statistical analysis of modeled [CO32−] variance and autocorrelation suggests that significant anthropogenic trends in the saturation state of aragonite (Ωaragonite are already or nearly detectable at the sustained, open-ocean time series sites, whereas several decades of observations are required to detect anthropogenic trends in Ωaragonite in the tropical Pacific, North Pacific, and North Atlantic. The detection timescale for anthropogenic trends in pH is shorter than that for Ωaragonite, due to smaller noise-to-signal ratios and lower autocorrelation in pH. In the tropical Pacific, the leading mode of surface [CO32−] variability is primarily driven by variations in the vertical advection of dissolved inorganic carbon (DIC in association with El Niño–Southern Oscillation. In the North Pacific, surface [CO32−] variability is caused by circulation-driven variations in surface DIC and strongly correlated with the Pacific Decadal Oscillation, with peak spectral power at 20–30-year periods. North Atlantic [CO32−] variability is also driven by variations in surface DIC, and exhibits weak correlations with both the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation. As the scientific community seeks to detect the anthropogenic influence on ocean carbonate chemistry, these results

  19. Natural variability in the surface ocean carbonate ion concentration

    Science.gov (United States)

    Lovenduski, N. S.; Long, M. C.; Lindsay, K.

    2015-11-01

    We investigate variability in the surface ocean carbonate ion concentration ([CO32-]) on the basis of a~long control simulation with an Earth System Model. The simulation is run with a prescribed, pre-industrial atmospheric CO2 concentration for 1000 years, permitting investigation of natural [CO32-] variability on interannual to multi-decadal timescales. We find high interannual variability in surface [CO32-] in the tropical Pacific and at the boundaries between the subtropical and subpolar gyres in the Northern Hemisphere, and relatively low interannual variability in the centers of the subtropical gyres and in the Southern Ocean. Statistical analysis of modeled [CO32-] variance and autocorrelation suggests that significant anthropogenic trends in the saturation state of aragonite (Ωaragonite) are already or nearly detectable at the sustained, open-ocean time series sites, whereas several decades of observations are required to detect anthropogenic trends in Ωaragonite in the tropical Pacific, North Pacific, and North Atlantic. The detection timescale for anthropogenic trends in pH is shorter than that for Ωaragonite, due to smaller noise-to-signal ratios and lower autocorrelation in pH. In the tropical Pacific, the leading mode of surface [CO32-] variability is primarily driven by variations in the vertical advection of dissolved inorganic carbon (DIC) in association with El Niño-Southern Oscillation. In the North Pacific, surface [CO32-] variability is caused by circulation-driven variations in surface DIC and strongly correlated with the Pacific Decadal Oscillation, with peak spectral power at 20-30-year periods. North Atlantic [CO32-] variability is also driven by variations in surface DIC, and exhibits weak correlations with both the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation. As the scientific community seeks to detect the anthropogenic influence on ocean carbonate chemistry, these results will aid the interpretation of trends

  20. Spatial and temporal control of the diazonium modification of sp2 carbon surfaces.

    Science.gov (United States)

    Kirkman, Paul M; Güell, Aleix G; Cuharuc, Anatolii S; Unwin, Patrick R

    2014-01-08

    Interest in the controlled chemical functionalization of sp(2) carbon materials using diazonium compounds has been recently reignited, particularly as a means to generate a band gap in graphene. We demonstrate local diazonium modification of pristine sp(2) carbon surfaces, with high control, at the micrometer scale through the use of scanning electrochemical cell microscopy (SECCM). Electrochemically driven diazonium patterning is investigated at a range of driving forces, coupled with surface analysis using atomic force microscopy (AFM) and Raman spectroscopy. We highlight how the film density, level of sp(2)/sp(3) rehybridization and the extent of multilayer formation can be controlled, paving the way for the use of localized electrochemistry as a route to controlled diazonium modification.

  1. Osteoblast cell response to surface-modified carbon nanotubes

    International Nuclear Information System (INIS)

    Zhang Faming; Weidmann, Arne; Nebe, J. Barbara; Burkel, Eberhard

    2012-01-01

    In order to investigate the interaction of cells with modified multi-walled carbon nanotubes (MWCNTs) for their potential biomedical applications, the MWCNTs were chemically modified with carboxylic acid groups (–COOH), polyvinyl alcohol (PVA) polymer and biomimetic apatite on their surfaces. Additionally, human osteoblast MG-63 cells were cultured in the presence of the surface-modified MWCNTs. The metabolic activities of osteoblastic cells, cell proliferation properties, as well as cell morphology were studied. The surface modification of MWCNTs with biomimetic apatite exhibited a significant increase in the cell viability of osteoblasts, up to 67.23%. In the proliferation phases, there were many more cells in the biomimetic apatite-modified MWCNT samples than in the MWCNTs–COOH. There were no obvious changes in cell morphology in osteoblastic MG-63 cells cultured in the presence of these chemically-modified MWCNTs. The surface modification of MWCNTs with apatite achieves an effective enhancement of their biocompatibility.

  2. Surface functional groups in capacitive deionization with porous carbon electrodes

    Science.gov (United States)

    Hemmatifar, Ali; Oyarzun, Diego I.; Palko, James W.; Hawks, Steven A.; Stadermann, Michael; Santiago, Juan G.; Stanford Microfluidics Lab Team; Lawrence Livermore National Lab Team

    2017-11-01

    Capacitive deionization (CDI) is a promising technology for removal of toxic ions and salt from water. In CDI, an applied potential of about 1 V to pairs of porous electrodes (e.g. activated carbon) induces ion electromigration and electrostatic adsorption at electrode surfaces. Immobile surface functional groups play a critical role in the type and capacity of ion adsorption, and this can dramatically change desalination performance. We here use models and experiments to study weak electrolyte surface groups which protonate and/or depropotante based on their acid/base dissociation constants and local pore pH. Net chemical surface charge and differential capacitance can thus vary during CDI operation. In this work, we present a CDI model based on weak electrolyte acid/base equilibria theory. Our model incorporates preferential cation (anion) adsorption for activated carbon with acidic (basic) surface groups. We validated our model with experiments on custom built CDI cells with a variety of functionalizations. To this end, we varied electrolyte pH and measured adsorption of individual anionic and cationic ions using inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography (IC) techniques. Our model shows good agreement with experiments and provides a framework useful in the design of CDI control schemes.

  3. Functionalized granular activated carbon and surface complexation with chromates and bi-chromates in wastewater

    International Nuclear Information System (INIS)

    Singha, Somdutta; Sarkar, Ujjaini; Luharuka, Pallavi

    2013-01-01

    Cr(VI) is present in the aqueous medium as chromate (CrO 4 2− ) and bi-chromate (HCrO 4 − ). Functionalized granular activated carbons (FACs) are used as adsorbents in the treatment of wastewaters containing hexavalent chromium. The FACs are prepared by chemical modifications of granular activated carbons (GACs) using functionalizing agents like HNO 3 , HCl and HF. The Brunauer, Emmett and Teller surface areas of FAC-HCl (693.5 m 2 /g), FAC-HNO 3 (648.8 m 2 /g) and FAC-HF (726.2 m 2 /g) are comparable to the GAC (777.7 m 2 /g). But, the adsorption capacity of each of the FAC-HNO 3 , FAC-HCl and FAC-HF is found to be higher than the GAC. The functional groups play an important role in the adsorption process and pH has practically no role in this specific case. The FACs have hydrophilic protonated external surfaces in particular, along with the functional surface sites capable to make complexes with the CrO 4 2− and HCrO 4 − present. Surface complex formation is maximized in the order FAC-HNO 3 > FAC-HF > FAC-HCl, in proportion to the total surface acidity. This is also confirmed by the well-known pseudo second-order kinetic model. Physi-sorption equilibrium isotherms are parameterized by using standard Freundlich and Langmuir models. Langmuir fits better. The formation of surface complexes with the functional groups and hexavalent chromium is also revealed in the images of field emission scanning electron micrograph; energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy analysis after adsorption. The intra-particle diffusion is not the only rate-controlling factor. The Boyd's film diffusion model fits very well with R 2 as high as 98.1% for FAC-HNO 3 . This result demonstrates that the functionalization of the GAC by acid treatments would increase the diffusion rate, predominantly with a boundary layer diffusion effect. - Highlights: ► Physico-chemical adsorption using functionalized activated carbon (FACs) is applied. ► FACs

  4. Interactions between bubble formation and heating surface in nucleate boiling

    International Nuclear Information System (INIS)

    Luke, Andrea

    2009-01-01

    The heat transfer and bubble formation is investigated in pool boiling of propane. Size distributions of active nucleation sites on single horizontal copper and steel tubes with different diameter and surface finishes have been calculated from heat transfer measurements over wide ranges of heat flux and selected pressure. The model assumptions of Luke and Gorenflo for the heat transfer near growing and departing bubbles, which were applied in the calculations, have been slightly modified and the calculated results have been compared to experimental investigations by high speed video techniques. The calculated number of active sites shows a good coincidence for the tube with smaller diameter, while the results for the tube with larger diameter describe the same relative increase of the active sites. The comparison of the cumulative size distribution of the active and potential nucleation sites demonstrates the same slope of the curve and that the critical radius of a stable bubble nuclei is smaller than the average cavity size. (author)

  5. Interactions between bubble formation and heating surface in nucleate boiling

    Energy Technology Data Exchange (ETDEWEB)

    Luke, Andrea [Leibniz University, Hannover (Denmark). Inst. of Thermodynamics], e-mail: ift@ift.uni-hannover.de

    2009-07-01

    The heat transfer and bubble formation is investigated in pool boiling of propane. Size distributions of active nucleation sites on single horizontal copper and steel tubes with different diameter and surface finishes have been calculated from heat transfer measurements over wide ranges of heat flux and selected pressure. The model assumptions of Luke and Gorenflo for the heat transfer near growing and departing bubbles, which were applied in the calculations, have been slightly modified and the calculated results have been compared to experimental investigations by high speed video techniques. The calculated number of active sites shows a good coincidence for the tube with smaller diameter, while the results for the tube with larger diameter describe the same relative increase of the active sites. The comparison of the cumulative size distribution of the active and potential nucleation sites demonstrates the same slope of the curve and that the critical radius of a stable bubble nuclei is smaller than the average cavity size. (author)

  6. Formation of a highly doped ultra-thin amorphous carbon layer by ion bombardment of graphene

    Science.gov (United States)

    Piotr Michałowski, Paweł; Pasternak, Iwona; Ciepielewski, Paweł; Guinea, Francisco; Strupiński, Włodek

    2018-07-01

    Ion bombardment of graphene leads to the formation of defects which may be used to tune properties of the graphene based devices. In this work, however, we present that the presence of the graphene layer on a surface of a sample has a significant impact on the ion bombardment process: broken sp2 bonds react with the incoming ions and trap them close to the surface of the sample, preventing a standard ion implantation. For an ion bombardment with a low impact energy and significant dose (in the range of 1014 atoms cm‑2) an amorphization of the graphene layer is observed but at the same time, most of the incoming ions do not penetrate the sample but stop at the surface, thus forming a highly doped ultra-thin amorphous carbon layer. The effect may be used to create thin layers containing desired atoms if no other technique is available. This approach is particularly useful for secondary ion mass spectrometry where a high concentration of Cs at the surface of a sample significantly enhances the negative ionization probability, allowing it to reach better detection limits.

  7. Carbon-based nanostructured surfaces for enhanced phase-change cooling

    Science.gov (United States)

    Selvaraj Kousalya, Arun

    . Nanostructured samples having a thicker copper coating provided a considerable increase in dryout heat flux while maintaining lower surface superheat temperatures compared to a bare sintered powder sample; this enhancement is attributed primarily to the improved surface wettability. Dynamic contact angle measurements are conducted to quantitatively compare the surface wetting trends for varying copper coating thicknesses and confirm the increase in hydrophilicity with increasing coating thickness. The second and relatively new carbon nanostructured coating, carbon nanotubes decorated with graphitic nanopetals, are used as a template to manufacture boiling surfaces with heterogeneous wettability. Heat transfer surfaces with parallel alternating superhydrophobic and superhydrophilic stripes are fabricated by a combination of oxygen plasma treatment, Teflon coating and shadow masking. Such composite wetting surfaces exhibit enhanced flow-boiling performance compared to homogeneous wetting surfaces. Flow visualization studies elucidate the physical differences in nucleate boiling mechanisms between the different heterogeneous wetting surfaces. The third and the final carbon nanomaterial, graphene, is examined as an oxidation barrier coating for liquid and liquid-vapor phase-change cooling systems. Forced convection heat transfer experiments on bare and graphene-coated copper surfaces reveal nearly identical liquid-phase and two-phase thermal performance for the two surfaces. Surface analysis after thermal testing indicates significant oxide formation on the entire surface of the bare copper substrate; however, oxidation is observed only along the grain boundaries of the graphene-coated substrate. Results suggest that few-layer graphene can act as a protective layer even under vigorous flow boiling conditions, indicating a broad application space of few-layer graphene as an ultra-thin oxidation barrier coating.

  8. Comparative Study on the Solid Electrolyte Interface Formation by the Reduction of Alkyl Carbonates in Lithium ion Battery

    International Nuclear Information System (INIS)

    Haregewoin, Atetegeb Meazah; Leggesse, Ermias Girma; Jiang, Jyh-Chiang; Wang, Fu-Ming; Hwang, Bing-Joe; Lin, Shawn D.

    2014-01-01

    Mixed alkyl carbonates are widely used as solvent for a various lithium-ion battery applications. Understanding the behavior of each solvent in the mixed system is crucial for controlling the electrolyte composition. In this paper, we report a systematic electrochemical and spectroscopic comparison of the reduction of propylene carbonate (PC), ethylene carbonate (EC), and diethyl carbonate (DEC) when used as single (PC), binary (EC/PC, EC/DEC), and ternary (EC/PC/DEC) solvent systems. The reduction products are identified based on Fourier transform infrared spectroscopy (FTIR) after employing linear sweep voltammetry to certain potential regions and their possible formation mechanisms are discussed. FTIR analyses revealed that the reduction of EC and PC was not considerably influenced by the presence of other alkyl carbonates. However, DEC exhibited a different reduction product when used in EC/DEC and EC/PC/DEC solvent systems. The reduction of EC occurred before that of PC and DEC and produced a passivating surface film that prevented carbon exfoliation caused by PC. Battery performance test, cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscope is employed to study the surface films formed. The binary EC/DEC solvent system demonstrated more favorable performance, smaller impedance, and higher Li + ion diffusivity than did the other solvent systems used in this study

  9. Tungsten and carbon surface change under high dose plasma exposure

    International Nuclear Information System (INIS)

    Martynenko, Y.V.; Khripunov, B.I.; Petrov, V.B.

    2009-01-01

    Study of surface composition dynamics has been made on the LENTA linear plasma simulator. Experiments have been made on tungsten and carbon materials subjected to steady-state plasma exposure. The achieved ion doses on the surface were 10 21 ion cm -2 . WL 10 tungsten containing 1% of La2O3 oxide and titanium-doped graphite RG-T were studied. The following experimental conditions were varied in these experiments: energy of ions, surface temperature, working gas. Irradiations of tungsten WL 10 were executed in deuterium plasma at low ion energies (about 20 eV) and at 200 eV for temperatures below 340 K. Graphite RG-T was exposed at 1300 K. Elevated surface temperature (about 1050K) was also characteristic of experiments on tungsten sample under nitrogen plasma impact (simulated inter-ELMs condition). Surface microstructure modification has been observed and surface composition changes were found on the materials showing influence of high dose plasma irradiations on element redistribution in the near surface layers. (author)

  10. Low-Dimensional Network Formation in Molten Sodium Carbonate.

    Science.gov (United States)

    Wilding, Martin C; Wilson, Mark; Alderman, Oliver L G; Benmore, Chris; Weber, J K R; Parise, John B; Tamalonis, Anthony; Skinner, Lawrie

    2016-04-15

    Molten carbonates are highly inviscid liquids characterized by low melting points and high solubility of rare earth elements and volatile molecules. An understanding of the structure and related properties of these intriguing liquids has been limited to date. We report the results of a study of molten sodium carbonate (Na2CO3) which combines high energy X-ray diffraction, containerless techniques and computer simulation to provide insight into the liquid structure. Total structure factors (F(x)(Q)) are collected on the laser-heated carbonate spheres suspended in flowing gases of varying composition in an aerodynamic levitation furnace. The respective partial structure factor contributions to F(x)(Q) are obtained by performing molecular dynamics simulations treating the carbonate anions as flexible entities. The carbonate liquid structure is found to be heavily temperature-dependent. At low temperatures a low-dimensional carbonate chain network forms, at T = 1100 K for example ~55% of the C atoms form part of a chain. The mean chain lengths decrease as temperature is increased and as the chains become shorter the rotation of the carbonate anions becomes more rapid enhancing the diffusion of Na(+) ions.

  11. The laser surface alloying of the surface layer of the plain carbon steel

    International Nuclear Information System (INIS)

    Woldan, A.; Kusinski, J.

    2003-01-01

    The paper describes the microstructure and properties (chemical composition, microhardness and the effect of tribological test of the surface laser alloyed layer with tantalum. Scanning electron microscopy examinations show structure, which consist of martensite and Ta2C carbides. Samples covered with Ta and the carbon containing binder showed after laser alloying higher hardness than in case of using silicon-containing binder. (author)

  12. Ultrahigh surface area carbon from carbonated beverages: Combining self-templating process and in situ activation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Pengfei; Zhang, Zhiyong; Chen, Jihua; Dai, Sheng

    2015-11-01

    Ultrahigh surface area carbons (USACs, e.g., >2000 m2/g) are attracting tremendous attention due to their outstanding performance in energy-related applications. The state-of-art approaches to USACs involve templating or activation methods and all these techniques show certain drawbacks. In this work, a series of USACs with specific surface areas up to 3633 m2/g were prepared in two steps: hydrothermal carbonization (200 °C) of carbonated beverages (CBs) and further thermal treatment in nitrogen (600–1000 °C). The rich inner porosity is formed by a self-templated process during which acids and polyelectrolyte sodium salts in the beverage formulas make some contribution. This strategy covers various CBs such as Coca Cola®, Pepsi Cola®, Dr. Pepper®, and Fanta® and it enables an acceptable product yield (based on sugars), for example: 21 wt% for carbon (2940 m2/g) from Coca Cola®. Being potential electrode materials for supercapacitors, those carbon materials possessed a good specific capacitance (57.2–185.7 F g-1) even at a scan rate of 1000 mV s-1. Thus, a simple and efficient strategy to USACs has been presented.

  13. Characterization of a surface modified carbon cryogel and a carbon supported Pt catalyst

    Directory of Open Access Journals (Sweden)

    BILJANA M. BABIĆ

    2007-08-01

    Full Text Available A carbon cryogel, synthesized by carbonization of a resorcinol/formaldehyde cryogel and oxidized in nitric acid, was used as catalyst support for Pt nano-particles. The Pt/C catalyst was prepared by a modified polyol synthesis method in an ethylene glycol (EG solution. Characterization by nitrogen adsorption showed that the carbon cryogel support and the Pt/C catalyst were mesoporous materials with high specific surface areas (SBET > 400 m2 g-1 and large mesoporous volumes. X-Ray diffraction of the catalyst demonstrated the successful reduction of the Pt precursor to metallic form. TEM Images of the Pt/C catalyst and Pt particle size distribution showed that the mean Pt particle size was about 3.3 nm. Cyclic voltammetry (CV experiments at various scan rates (from 2 to 200 mV s-1 were performed in 0.5 mol dm-3 HClO4 solution. The large capacitance of the oxidized carbon cryogel electrode, which arises from a combination of the double-layer capacitance and pseudocapacitance, associated with the participation of surface redox-type reactions was demonstrated. For the oxidized carbon cryogel, the total specific capacitance determined by 1/C vs. ν0.5 extrapolation method was found to be 386 F g-1. The hydrogen oxidation reaction at the investigated Pt/C catalyst proceeded as an electrochemically reversible, two-electron direct discharge reaction.

  14. Arsenic Sulfide Nanowire Formation on Fused Quartz Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Olmstead, J.; Riley, B.J.; Johnson, B.R.; Sundaram, S.K.

    2005-01-01

    Arsenic sulfide (AsxSy) nanowires were synthesized by an evaporation-condensation process in evacuated fused quartz ampoules. During the deposition process, a thin, colored film of AsxSy was deposited along the upper, cooler portion of the ampoule. The ampoule was sectioned and the deposited film analyzed using scanning electron microscopy (SEM) to characterize and semi-quantitatively evaluate the microstructural features of the deposited film. A variety of microstructures were observed that ranged from a continuous thin film (warmer portion of the ampoule), to isolated micron- and nano-scale droplets (in the intermediate portion), as well as nanowires (colder portion of the ampoule). Experiments were conducted to evaluate the effects of ampoule cleaning methods (e.g. modify surface chemistry) and quantity of source material on nanowire formation. The evolution of these microstructures in the thin film was determined to be a function of initial pressure, substrate temperature, substrate surface treatment, and initial volume of As2S3 glass. In a set of two experiments where the initial pressure, substrate thermal gradient, and surface treatment were the same, the initial quantity of As2S3 glass per internal ampoule volume was doubled from one test to the other. The results showed that AsxSy nanowires were only formed in the test with the greater initial quantity of As2S3 per internal ampoule volume. The growth data for variation in diameter (e.g. nanowire or droplet) as a function of substrate temperature was fit to an exponential trendline with the form y = Aekx, where y is the structure diameter, A = 1.25×10-3, k = 3.96×10-2, and x is the temperature with correlation coefficient, R2 = 0.979, indicating a thermally-activated process.

  15. Protein-free formation of bone-like apatite: New insights into the key role of carbonation.

    Science.gov (United States)

    Deymier, Alix C; Nair, Arun K; Depalle, Baptiste; Qin, Zhao; Arcot, Kashyap; Drouet, Christophe; Yoder, Claude H; Buehler, Markus J; Thomopoulos, Stavros; Genin, Guy M; Pasteris, Jill D

    2017-05-01

    The nanometer-sized plate-like morphology of bone mineral is necessary for proper bone mechanics and physiology. However, mechanisms regulating the morphology of these mineral nanocrystals remain unclear. The dominant hypothesis attributes the size and shape regulation to organic-mineral interactions. Here, we present data supporting the hypothesis that physicochemical effects of carbonate integration within the apatite lattice control the morphology, size, and mechanics of bioapatite mineral crystals. Carbonated apatites synthesized in the absence of organic molecules presented plate-like morphologies and nanoscale crystallite dimensions. Experimentally-determined crystallite size, lattice spacing, solubility and atomic order were modified by carbonate concentration. Molecular dynamics (MD) simulations and density functional theory (DFT) calculations predicted changes in surface energy and elastic moduli with carbonate concentration. Combining these results with a scaling law predicted the experimentally observed scaling of size and energetics with carbonate concentration. The experiments and models describe a clear mechanism by which crystal dimensions are controlled by carbonate substitution. Furthermore, the results demonstrate that carbonate substitution is sufficient to drive the formation of bone-like crystallites. This new understanding points to pathways for biomimetic synthesis of novel, nanostructured biomaterials. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Surface modifications of polypropylene by high energy carbon ions

    International Nuclear Information System (INIS)

    Saha, A.; Chakraborty, V.; Dutta, R.K.; Chintalapudi, S.N.

    2000-01-01

    Polypropylene was irradiated with 12 C ions of 3.6 and 5.4 MeV energies using 3 MV tandem accelerator. The surface modification was investigated by Scanning Electron Microscopy (SEM). Optical changes were monitored by UV-VIS and FTIR spectroscopy. At the lowest ion fluence, only blister formation of various sizes (1-6 μm) was observed. Polymer when irradiated at a fluence of 1x10 14 ions/cm 2 exhibited a network structure. A comparative study on dose dependence of surface and bulk modification has been described. (author)

  17. Cathode deposits in fullerene formation — microstructural evidence for independent pathways of pyrolytic carbon and nanobody formation

    Science.gov (United States)

    Taylor, G. H.; Gerald, J. D. Fitz; Pang, L.; Wilson, M. A.

    1994-01-01

    Microstructures in cathode deposits formed during fullerene production by electrical arcing in helium have been examined in detail. This has provided new information about the mechanisms by which nanobodies (nanotubes and nanoparticles) and pyrolytic carbon are deposited. Nanobodies and pyrolytic carbon form independently; the former probably grow in the plasma then deposit on the electrode but much of the latter deposits directly on the electrode surface.

  18. Soil Carbon Dioxide Production and Surface Fluxes: Subsurface Physical Controls

    Science.gov (United States)

    Risk, D.; Kellman, L.; Beltrami, H.

    Soil respiration is a critical determinant of landscape carbon balance. Variations in soil temperature and moisture patterns are important physical processes controlling soil respiration which need to be better understood. Relationships between soil respi- ration and physical controls are typically addressed using only surface flux data but other methods also exist which permit more rigorous interpretation of soil respira- tion processes. Here we use a combination of subsurface CO_{2} concentrations, surface CO_{2} fluxes and detailed physical monitoring of the subsurface envi- ronment to examine physical controls on soil CO_{2} production at four climate observatories in Eastern Canada. Results indicate that subsurface CO_{2} produc- tion is more strongly correlated to the subsurface thermal environment than the surface CO_{2} flux. Soil moisture was also found to have an important influence on sub- surface CO_{2} production, particularly in relation to the soil moisture - soil profile diffusivity relationship. Non-diffusive profile CO_{2} transport appears to be im- portant at these sites, resulting in a de-coupling of summertime surface fluxes from subsurface processes and violating assumptions that surface CO_{2} emissions are the result solely of diffusion. These results have implications for the study of soil respiration across a broad range of terrestrial environments.

  19. Interaction of scandium and titanium atoms with a carbon surface containing five- and seven-membered rings

    International Nuclear Information System (INIS)

    Krasnov, P. O.; Eliseeva, N. S.; Kuzubov, A. A.

    2012-01-01

    The use of carbon nanotubes coated by atoms of transition metals to store molecular hydrogen is associated with the problem of the aggregation of these atoms, which leads to the formation of metal clusters. The quantum-chemical simulation of cluster models of the carbon surface of a graphene type with scandium and titanium atoms has been performed. It has been shown that the presence of five- and seven-membered rings, in addition to six-membered rings, in these structures makes it possible to strongly suppress the processes of the migration of metal atoms over the surface, preventing their clustering.

  20. Radiation grafting of methacrylate onto carbon nanofiber surface

    International Nuclear Information System (INIS)

    Evora, M.C.; Klosterman, D.; Lafdi, K.; Li, L.

    2011-01-01

    Radiation can be used to modify and improve the properties of materials. Electron beam irradiation has potential application in modifying the structure of carbon fibers in order to produce useful defects in the graphite structure and create reactive sites. In this study, vapor grown carbon nano fibers (VGCF) were irradiated with a high energy (3 MeV) electron beam in air to dose of 1000 kGy to create active sites and added to methyl methacrylate (MMA) dissolved in water/methanol (50% V). The irradiated samples were analyzed by X-Ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy to assess the impact on surface and bulk properties. Oxygen was readily incorporated enhancing the dispersion of VGCF. Raman spectroscopy analyses indicated that the sample irradiated and preirradiated grafted sample with MMA had the intensity ratio increased. (author)

  1. The Effect of Carbon Source and Fluoride Concentrations in the "Streptococcus Mutans" Biofilm Formation

    Science.gov (United States)

    Paulino, Tony P.; Andrade, Ricardo O.; Bruschi-Thedei, Giuliana C. M.; Thedei, Geraldo, Jr.; Ciancaglini, Pietro

    2004-01-01

    The main objective of this class experiment is to show the influence of carbon source and of different fluoride concentrations on the biofilm formation by the bacterium "Streptococcus mutans." The observation of different biofilm morphology as a function of carbon source and fluoride concentration allows an interesting discussion regarding the…

  2. Palladium on Nitrogen-Doped Mesoporous Carbon: A Bifunctional Catalyst for Formate-Based, Carbon-Neutral Hydrogen Storage.

    Science.gov (United States)

    Wang, Fanan; Xu, Jinming; Shao, Xianzhao; Su, Xiong; Huang, Yanqiang; Zhang, Tao

    2016-02-08

    The lack of safe, efficient, and economical hydrogen storage technologies is a hindrance to the realization of the hydrogen economy. Reported herein is a reversible formate-based carbon-neutral hydrogen storage system that is established over a novel catalyst comprising palladium nanoparticles supported on nitrogen-doped mesoporous carbon. The support was fabricated by a hard template method and nitridated under a flow of ammonia. Detailed analyses demonstrate that this bicarbonate/formate redox equilibrium is promoted by the cooperative role of the doped nitrogen functionalities and the well-dispersed, electron-enriched palladium nanoparticles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Water entry without surface seal: Extended cavity formation

    KAUST Repository

    Mansoor, Mohammad M.

    2014-03-01

    We report results from an experimental study of cavity formation during the impact of superhydrophobic spheres onto water. Using a simple splash-guard mechanism, we block the spray emerging during initial contact from closing thus eliminating the phenomenon known as \\'surface seal\\', which typically occurs at Froude numbers Fr= V0 2/(gR0) = O(100). As such, we are able to observe the evolution of a smooth cavity in a more extended parameter space than has been achieved in previous studies. Furthermore, by systematically varying the tank size and sphere diameter, we examine the influence of increasing wall effects on these guarded impact cavities and note the formation of surface undulations with wavelength λ =O(10)cm and acoustic waves λa=O(D0) along the cavity interface, which produce multiple pinch-off points. Acoustic waves are initiated by pressure perturbations, which themselves are generated by the primary cavity pinch-off. Using high-speed particle image velocimetry (PIV) techniques we study the bulk fluid flow for the most constrained geometry and show the larger undulations ( λ =O (10cm)) have a fixed nature with respect to the lab frame. We show that previously deduced scalings for the normalized (primary) pinch-off location (ratio of pinch-off depth to sphere depth at pinch-off time), Hp/H = 1/2, and pinch-off time, τ α (R0/g) 1/2, do not hold for these extended cavities in the presence of strong wall effects (sphere-to-tank diameter ratio), ε = D 0/Dtank 1/16. Instead, we find multiple distinct regimes for values of Hp/H as the observed undulations are induced above the first pinch-off point as the impact speed increases. We also report observations of \\'kinked\\' pinch-off points and the suppression of downward facing jets in the presence of wall effects. Surprisingly, upward facing jets emanating from first cavity pinch-off points evolve into a \\'flat\\' structure at high impact speeds, both in the presence and absence of wall effects.

  4. Growth mechanism of graphene on platinum: Surface catalysis and carbon segregation

    International Nuclear Information System (INIS)

    Sun, Jie; Lindvall, Niclas; Yurgens, August; Nam, Youngwoo; Cole, Matthew T.; Teo, Kenneth B. K.; Woo Park, Yung

    2014-01-01

    A model of the graphene growth mechanism of chemical vapor deposition on platinum is proposed and verified by experiments. Surface catalysis and carbon segregation occur, respectively, at high and low temperatures in the process, representing the so-called balance and segregation regimes. Catalysis leads to self-limiting formation of large area monolayer graphene, whereas segregation results in multilayers, which evidently “grow from below.” By controlling kinetic factors, dominantly monolayer graphene whose high quality has been confirmed by quantum Hall measurement can be deposited on platinum with hydrogen-rich environment, quench cooling, tiny but continuous methane flow and about 1000 °C growth temperature

  5. Chemically immobilised carbon nanotubes on silicon: Stable surfaces for aqueous electrochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Flavel, Benjamin S., E-mail: ben.flavel@flinders.edu.a [Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch 8140 (New Zealand); School of Chemistry, Physics and Earth Sciences, Flinders University, Sturt Road, Bedford Park, Adelaide, South Australia 5001 (Australia); Garrett, David J.; Lehr, Joshua [Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch 8140 (New Zealand); MacDiarmid Institute for Advanced Materials and Nanotechnology, Private Bag 4800, Christchurch 8140 (New Zealand); Shapter, Joseph G. [School of Chemistry, Physics and Earth Sciences, Flinders University, Sturt Road, Bedford Park, Adelaide, South Australia 5001 (Australia); Downard, Alison J., E-mail: alison.downard@canterbury.ac.n [Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch 8140 (New Zealand); MacDiarmid Institute for Advanced Materials and Nanotechnology, Private Bag 4800, Christchurch 8140 (New Zealand)

    2010-04-30

    Diazonium ion chemistry has been used to electrochemically graft aminophenyl layers onto p-type silicon (1 0 0) substrates. A condensation reaction was used to immobilise single-walled carbon nanotubes with high carboxylic acid functionality directly to this layer. Electrochemical monitoring of the aminophenyl groups confirmed the formation of an amide linkage between the single-walled carbon nanotubes and the aminophenyl layer. The carbon nanotube electrode showed high stability and good electrochemical performance in aqueous solution. At moderate scan rates the Ru(NH{sub 3}){sub 6}{sup +3/+2} couple exhibited quasi-reversible electron transfer kinetics with a standard heterogenous rate constant of 1.2 x 10{sup -3} cm s{sup -1} at the covalently-linked carbon nanotube surface. The electrode thus combines the advantages of a silicon substrate for easy integration into sophisticated electrical and electronic devices, carbon nanotubes for desirable electrochemical properties, and stability in aqueous medium for future applications in environmental sensing.

  6. Surface energy of amorphous carbon films containing iron

    International Nuclear Information System (INIS)

    Chen, J. S.; Lau, S. P.; Tay, B. K.; Chen, G. Y.; Sun, Z.; Tan, Y. Y.; Tan, G.; Chai, J. W.

    2001-01-01

    Iron containing diamond-like amorphous carbon (a-C:Fe) films were deposited by filtered cathodic vacuum arc technique. The influences of Fe content and substrate bias on the surface energy of the films were investigated. The surface energy of a-C:Fe films was determined by the contact angle measurement. Atomic force microscopy, Raman spectroscopy, and x-ray induced photoelectron spectroscopy were employed to analyze the origin of the variation of surface energy with various Fe content and substrate bias. It is found that the contact angle for water increases significantly after incorporating Fe into the films and the films become hydrophobic. The roughness of these films has no effect on the contact angle. The surface energy is reduced from 42.8 to 25 dyne/cm after incorporating Fe into the a-C film (10% Fe in the target), which is due to the reduction of both dispersive and polar component. The reduction in dispersive component is ascribed to the decrease of atomic density of the a-C:Fe films due to the increase in sp 2 bonded carbon. When sp 2 content increases to some extent, the atomic density remains constant and hence dispersive component does not change. The absorption of oxygen on the surface plays an important role in the reduction of the polar component for the a-C:Fe films. It is proposed that such network as (C n - O - Fe) - O - (Fe - O - C n ) may be formed and responsible for the reduction of polar component. [copyright] 2001 American Institute of Physics

  7. Characterization of transfer layers on steel surfaces sliding against diamondlike carbon in dry nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, A.; Bindal, C.; Pagan, J. [Argonne National Lab., IL (United States); Wilbur, P. [Colorado State Univ., Fort Collins, CO (United States). Dept. of Mechanical Engineering

    1995-03-01

    Transfer layers on sliding steel surfaces play important roles in tribological performance of diamondlike carbon films. This study investigated the nature of transfer layers formed on M50 balls during sliding against diamondlike carbon (DLC) films (1.5 {mu}m thick) prepared by ion-beam deposition. Long-duration sliding tests were performed with steel balls sliding against the DLC coatings in dry nitrogen at room temperature and zero humidity. Test results indicated that the friction coefficients of test pairs were initially 0.12 but decreased steadily with sliding distance to 0.02-0.03 and remained constant throughout the tests, which lasted for more than 250,000 sliding cycles (30 km). This low-friction regime appeared to coincide with the formation of a carbon-rich transfer layer on the sliding surfaces of M50 balls. Micro-laser-Raman spectroscopy and electron microscopy were used to elucidate the structure and chemistry of these transfer layers and to reveal their possible role in the wear and friction behavior of DLC-coated surfaces.

  8. Highly Efficient Catalytic Cyclic Carbonate Formation by Pyridyl Salicylimines.

    Science.gov (United States)

    Subramanian, Saravanan; Park, Joonho; Byun, Jeehye; Jung, Yousung; Yavuz, Cafer T

    2018-03-21

    Cyclic carbonates as industrial commodities offer a viable nonredox carbon dioxide fixation, and suitable heterogeneous catalysts are vital for their widespread implementation. Here, we report a highly efficient heterogeneous catalyst for CO 2 addition to epoxides based on a newly identified active catalytic pocket consisting of pyridine, imine, and phenol moieties. The polymeric, metal-free catalyst derived from this active site converts less-reactive styrene oxide under atmospheric pressure in quantitative yield and selectivity to the corresponding carbonate. The catalyst does not need additives, solvents, metals, or co-catalysts, can be reused at least 10 cycles without the loss of activity, and scaled up easily to a kilogram scale. Density functional theory calculations reveal that the nucleophilicity of pyridine base gets stronger due to the conjugated imines and H-bonding from phenol accelerates the reaction forward by stabilizing the intermediate.

  9. TPR system: a powerful technique to monitor carbon nanotube formation during chemical vapour deposition

    International Nuclear Information System (INIS)

    Tristao, Juliana Cristina; Moura, Flavia Cristina Camilo; Lago, Rochel Montero; Sapag, Karim

    2010-01-01

    In this work, a TPR (Temperature Programmed Reduction) system is used as a powerful tool to monitor carbon nanotubes production during CVD (Chemical Vapour Deposition), The experiments were carried out using catalyst precursors based on Fe-Mo supported on Al 2 O 3 and methane as carbon source. As methane reacts on the Fe metal surface, carbon is deposited and H2 is produced. TPR is very sensitive to the presence of H2 and affords information on the temperature where catalyst is active to form different forms of carbon, the reaction kinetics, the catalyst deactivation and carbon yields. (author)

  10. Geological Sequestration of CO2 by Hydrous Carbonate Formation with Reclaimed Slag

    Energy Technology Data Exchange (ETDEWEB)

    Von L. Richards; Kent Peaslee; Jeffrey Smith

    2008-02-06

    The concept of this project is to develop a process that improves the kinetics of the hydrous carbonate formation reaction enabling steelmakers to directly remove CO2 from their furnace exhaust gas. It is proposed to bring the furnace exhaust stream containing CO2 in contact with reclaimed steelmaking slag in a reactor that has an environment near the unit activity of water resulting in the production of carbonates. The CO2 emissions from the plant would be reduced by the amount sequestered in the formation of carbonates. The main raw materials for the process are furnace exhaust gases and specially prepared slag.

  11. Mechanism of deposit formation on fuel-wetted metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Stavinoha, L.L.; Westbrook, S.R.; McInnis, L.A. [Southwest Research Institute, San Antonio, TX (United States)

    1995-05-01

    Experiments were performed in a Single-Tube Heat Exchanger (STHE) apparatus and a Hot Liquid Process Simulator (HLPS) configured and operated to meet Jet Fuel Thermal Oxidation Tester (JFTOT) ASTM D 3241 requirements. The HLPS-JFTOT heater tubes used were 1018 mild steel, 316 stainless steel (SS), 304 stainless steel (SS), and 304 SS tubes coated with aluminum, magnesium, gold, and copper. A low-sulfur Jet A fuel with a breakpoint temperature of 254{degrees}C was used to create deposits on the heater tubes at temperatures of 300{degrees}C, 340{degrees}C, and 380{degrees}C. Deposit thickness was measured by dielectric breakdown voltage and Auger ion milling. Pronounced differences between the deposit thickness measuring techniques suggested that both the Auger milling rate and the dielectric strength of the deposit may be affected by deposit morphology/composition (such as metal ions that may have become included in the bulk of the deposit). Carbon burnoff data were obtained as a means of judging the validity of DMD-derived deposit evaluations. ESCA data suggest that the thinnest deposit was on the magnesium-coated test tube. The Scanning Electron Microscope (SEM) photographs showed marked variations in the deposit morphology and the results suggested that surface composition has a significant effect on the mechanism of deposition. The most dramatic effect observed was that the bulk of deposits moved to tube locations of lower temperature as the maximum temperature of the tube was increased from 300{degrees} to 380{degrees}C, also verified in a single-tube heat exchanger. The results indicate that the deposition rate and quantity at elevated temperatures is not completely temperature dependent, but is limited by the concentration of dissolved oxygen and/or reactive components in the fuel over a temperature range.

  12. In situ formation of low friction ceramic coatings on carbon steel by plasma electrolytic oxidation in two types of electrolytes

    International Nuclear Information System (INIS)

    Wang Yunlong; Jiang Zhaohua

    2009-01-01

    In situ formation of ceramic coatings on Q235 carbon steel was achieved by plasma electrolytic oxidation (PEO) in carbonate electrolyte and silicate electrolyte, respectively. The surface and cross-section morphology, phase and elemental composition of PEO coatings were examined by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The bond strength of the coating was determined using a direct pull-off test. The hardness as well as tribological properties of the ceramic coating was primarily studied. The results indicated that the coating obtained in carbonate electrolyte was Fe 3 O 4 , while the coating achieved from silicate electrolyte was proved to be amorphous. Both kinds of coatings showed coarse and porous surface. The Fe 3 O 4 coatings obtained in carbonate electrolyte showed a high bonding strength to the substrate up to 20 ± 2 MPa and the value was 15 ± 2 MPa for the amorphous coatings obtained in carbonate electrolyte. The micro hardness of the amorphous coating and the Fe 3 O 4 coating was 1001 Hv and 1413 Hv, respectively, which was more than two and three times as that of the Q235 alloy substrate (415 Hv). The friction coefficient exhibited by amorphous coating and Fe 3 O 4 coating was 0.13 and 0.11, respectively, both lower than the uncoated Q235 substrate which ranged from 0.17 to 0.35.

  13. Apparatus and method for carbon fiber surface treatment

    Science.gov (United States)

    Paulauskas, Felix L; Sherman, Daniel M

    2014-06-03

    An apparatus and method for enhancing the surface energy and/or surface chemistry of carbon fibers involves exposing the fibers to direct or indirect contact with atmospheric pressure plasma generated using a background gas containing at least some oxygen or other reactive species. The fiber may be exposed directly to the plasma, provided that the plasma is nonfilamentary, or the fiber may be exposed indirectly through contact with gases exhausting from a plasma discharge maintained in a separate volume. In either case, the process is carried out at or near atmospheric pressure, thereby eliminating the need for vacuum equipment. The process may be further modified by moistening the fibers with selected oxygen-containing liquids before exposure to the plasma.

  14. Robust formation control of marine surface craft using Lagrange multipliers

    DEFF Research Database (Denmark)

    Ihle, Ivar-Andre F.; Jouffroy, Jerome; Fossen, Thor I.

    2006-01-01

    This paper presents a formation modelling scheme based on a set of inter-body constraint functions and Lagrangian multipliers. Formation control for a °eet of marine craft is achieved by stabilizing the auxiliary constraints such that the desired formation con¯guration appears. In the proposed fr...

  15. Formation of silicon carbide nanorods from wood-based carbons

    NARCIS (Netherlands)

    Hata, T; Castro, [No Value; Fujisawa, M; Imamura, Y; Bonnamy, S; Bronsveld, P; Kikuchi, H

    2005-01-01

    Man-made ceramic wood similar to petrified wood found in nature can be used at high temperature as the high oxidation rate of carbon above 500 degrees C is suppressed by a mu m thin SiC coating similar to the shuttle's heat shield. Possible applications are in the field of energy production, e.g.,

  16. Carbon dioxide emission from raised bog surface after peat extraction

    Directory of Open Access Journals (Sweden)

    Turbiak Janusz

    2017-12-01

    Full Text Available Research on CO2 emission from a raised bog after completion of peat extraction was performed in 2011–2013. CO2 emissions were determined by the chamber method. Twenty years after the termination of peat extraction, the bog surface was almost entirely devoid of plants. CO2 emission from the bog varied depending on temperature and water conditions and was 418 mg·m−2·h−1 on average during the research period. CO2 losses on the raised bog were on average 19.7 Mg·ha−1·year−1 during the research period which corresponded to a carbon loss of 5.37 Mg·ha−1·year−1 or mineralisation of 9.6 Mg·ha−1·year−1 of organic mass of 56% carbon content. It is possible to reduce organic mass losses and CO2 emission to the atmosphere from the bog surface after peat extraction has been terminated by reconstruction of initial water conditions, i.e. retaining a high ground water level and restoration of aquatic plant communities.

  17. Surface Complexation Modeling of Calcite Zeta Potential Measurement in Mixed Brines for Carbonate Wettability Characterization

    Science.gov (United States)

    Song, J.; Zeng, Y.; Biswal, S. L.; Hirasaki, G. J.

    2017-12-01

    We presents zeta potential measurements and surface complexation modeling (SCM) of synthetic calcite in various conditions. The systematic zeta potential measurement and the proposed SCM provide insight into the role of four potential determining cations (Mg2+, SO42- , Ca2+ and CO32-) and CO2 partial pressure in calcite surface charge formation and facilitate the revealing of calcite wettability alteration induced by brines with designed ionic composition ("smart water"). Brines with varying potential determining ions (PDI) concentration in two different CO2 partial pressure (PCO2) are investigated in experiments. Then, a double layer SCM is developed to model the zeta potential measurements. Moreover, we propose a definition for contribution of charged surface species and quantitatively analyze the variation of charged species contribution when changing brine composition. After showing our model can accurately predict calcite zeta potential in brines containing mixed PDIs, we apply it to predict zeta potential in ultra-low and pressurized CO2 environments for potential applications in carbonate enhanced oil recovery including miscible CO2 flooding and CO2 sequestration in carbonate reservoirs. Model prediction reveals that pure calcite surface will be positively charged in all investigated brines in pressurized CO2 environment (>1atm). Moreover, the sensitivity of calcite zeta potential to CO2 partial pressure in the various brine is found to be in the sequence of Na2CO3 > Na2SO4 > NaCl > MgCl2 > CaCl2 (Ionic strength=0.1M).

  18. Surface confined metallosupramolecular architectures: formation and scanning tunneling microscopy characterization.

    Science.gov (United States)

    Li, Shan-Shan; Northrop, Brian H; Yuan, Qun-Hui; Wan, Li-Jun; Stang, Peter J

    2009-02-17

    Metallosupramolecular compounds have attracted a great deal of attention over the past two decades largely because of their unique, highly complex structural characteristics and their potential electronic, magnetic, optical, and catalytic properties. These molecules can be prepared with relative ease using coordination-driven self-assembly techniques. In particular, the use of electron-poor square-planar Pt(II) transition metals in conjunction with rigid, electron-rich pyridyl donors has enabled the spontaneous self-assembly of a rich library of 2D metallacyclic and 3D metallacage assemblies via the directional-bonding approach. With this progress in the preparation and characterization of metallosupramolecules, researchers have now turned their attention toward fully exploring and developing their materials properties. Assembling metallosupramolecular compounds on solid supports represents a vitally important step toward developing their materials properties. Surfaces provide a means of uniformly aligning and orienting these highly symmetric metallacycles and metallacages. This uniformity increases the level of coherence between molecules above that which can be achieved in the solution phase and provides a way to integrate adsorbed layers, or adlayers, into a solid-state materials setting. The dynamic nature of kinetically labile Pt(II)-N coordination bonds requires us to adjust deposition and imaging conditions to retain the assemblies' stability. Toward these aims, we have used scanning tunneling microscopy (STM) to image these adlayers and to understand the factors that govern surface self-assembly and the interactions that influence their structure and stability. This Account describes our efforts to deposit 2D rectangular and square metallacycles and 3D trigonal bipyramidal and chiral trigonal prism metallacages on highly oriented pyrolytic graphite (HOPG) and Au(111) substrates to give intact assemblies and ordered adlayers. We have investigated the effects

  19. Relevance of carbon structure to formation of tar and liquid alkane during coal pyrolysis

    International Nuclear Information System (INIS)

    Liu, Peng; Le, Jiawei; Wang, Lanlan; Pan, Tieying; Lu, Xilan; Zhang, Dexiang

    2016-01-01

    Highlights: • Curve-fitting method was used to quantify the accurate contents of structural carbon. • Effect of carbon structure in coal with different rank on formation of pyrolysis tar was studied. • Numerical interrelation between carbon types in coal structure and tar yield is elaborated. • Effect of carbon structure on formation of liquid alkane during coal pyrolysis is discussed. - Abstract: The relevance of carbon structure to formation of tar and liquid alkane during coal pyrolysis were discussed extensively. The pyrolysis tests were carried out in a tube reactor at 873 K and keep 15 min. The carbon distribution in coals was investigated by solid state "1"3C nuclear magnetic resonance (N.M.R.). The curve-fitting method was used to quantify the accurate contents of structural carbon. The alkanes in coal tar were analyzed by Gas Chromatograph–Mass Spectrometer (GC–MS). The results show that oxygen-linked aromatic carbon decreases with the increasing of coal rank. The aliphatic carbon contents of Huainan (HN) coal are 44.20%, the highest among the four coals. The carbon types in coal structure have a significant influence on the formation of tar and liquid alkane. The coal tar yields are related to the aliphatic substituted aromatic carbon, CH_2/CH_3 ratio and oxygen-linked carbon in coal so that the increasing order of tar yield is Inner Mongolia lignite (IM, 6.30 wt.%) < Sinkiang coal (SK, 7.55 wt.%) < Shenmu coal (SM, 12.84 wt.%) < HN (16.29 wt.%). The highest contents of oxygen-linked aromatic carbon in IM lead to phenolic compound of 41.06% in IM-tar. The contents of alkane in SM-tar are the highest because the appropriate CH_2/CH_3 ratio and the highest aliphatic side chains on aromatic rings in SM leading to generate aliphatic hydrocarbon with medium molecular weight easily. The mechanism on formation of tar and liquid alkane plays an important role in guiding the industrialization of pyrolysis-based poly-generation producing tar with high

  20. Textural, surface, thermal and sorption properties of the functionalized activated carbons and carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Nowicki Piotr

    2015-12-01

    Full Text Available Two series of functionalised carbonaceous adsorbents were prepared by means of oxidation and nitrogenation of commercially available activated carbon and multi-walled carbon nanotubes. The effect of nitrogen and oxygen incorporation on the textural, surface, thermal and sorption properties of the adsorbents prepared was tested. The materials were characterized by elemental analysis, low-temperature nitrogen sorption, thermogravimetric study and determination of the surface oxygen groups content. Sorptive properties of the materials obtained were characterized by the adsorption of methylene and alkali blue 6B as well as copper(II ions. The final products were nitrogen- and oxygen-enriched mesoporous adsorbents of medium-developed surface area, showing highly diverse N and O-heteroatom contents and acidic-basic character of the surface. The results obtained in our study have proved that through a suitable choice of the modification procedure of commercial adsorbents it is possible to produce materials with high sorption capacity towards organic dyes as well as copper(II ions.

  1. Near-surface hydrogen depletion of diamond-like carbon films produced by direct ion deposition

    Science.gov (United States)

    Markwitz, Andreas; Gupta, Prasanth; Mohr, Berit; Hübner, René; Leveneur, Jerome; Zondervan, Albert; Becker, Hans-Werner

    2016-03-01

    Amorphous atomically flat diamond-like carbon (DLC) coatings were produced by direct ion deposition using a system based on a Penning ion source, butane precursor gas and post acceleration. Hydrogen depth profiles of the DLC coatings were measured with the 15N R-NRA method using the resonant nuclear reaction 1H(15N, αγ)12C (Eres = 6.385 MeV). The films produced at 3.0-10.5 kV acceleration voltage show two main effects. First, compared to average elemental composition of the film, the near-surface region is hydrogen depleted. The increase of the hydrogen concentration by 3% from the near-surface region towards the bulk is attributed to a growth model which favours the formation of sp2 hybridised carbon rich films in the film formation zone. Secondly, the depth at which the maximum hydrogen concentration is measured increases with acceleration voltage and is proportional to the penetration depth of protons produced by the ion source from the precursor gas. The observed effects are explained by a deposition process that takes into account the contributions of ion species, hydrogen effusion and preferential displacement of atoms during direct ion deposition.

  2. Near-surface hydrogen depletion of diamond-like carbon films produced by direct ion deposition

    Energy Technology Data Exchange (ETDEWEB)

    Markwitz, Andreas, E-mail: A.Markwitz@gns.cri.nz [GNS Science, Lower Hutt (New Zealand); The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Gupta, Prasanth [GNS Science, Lower Hutt (New Zealand); The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Mohr, Berit [GNS Science, Lower Hutt (New Zealand); Hübner, René [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (Germany); Leveneur, Jerome; Zondervan, Albert [GNS Science, Lower Hutt (New Zealand); Becker, Hans-Werner [RUBION, Ruhr-University Bochum (Germany)

    2016-03-15

    Amorphous atomically flat diamond-like carbon (DLC) coatings were produced by direct ion deposition using a system based on a Penning ion source, butane precursor gas and post acceleration. Hydrogen depth profiles of the DLC coatings were measured with the 15N R-NRA method using the resonant nuclear reaction {sup 1}H({sup 15}N, αγ){sup 12}C (E{sub res} = 6.385 MeV). The films produced at 3.0–10.5 kV acceleration voltage show two main effects. First, compared to average elemental composition of the film, the near-surface region is hydrogen depleted. The increase of the hydrogen concentration by 3% from the near-surface region towards the bulk is attributed to a growth model which favours the formation of sp{sup 2} hybridised carbon rich films in the film formation zone. Secondly, the depth at which the maximum hydrogen concentration is measured increases with acceleration voltage and is proportional to the penetration depth of protons produced by the ion source from the precursor gas. The observed effects are explained by a deposition process that takes into account the contributions of ion species, hydrogen effusion and preferential displacement of atoms during direct ion deposition.

  3. Comparison study of catalyst nanoparticle formation and carbon nanotube growth: Support effect

    International Nuclear Information System (INIS)

    Wang Yunyu; Luo Zhiquan; Li Bin; Ho, Paul S.; Yao Zhen; Shi Li; Bryan, Eugene N.; Nemanich, Robert J.

    2007-01-01

    A comparison study has been conducted on the formation of catalyst nanoparticles on a high surface tension metal and low surface tension oxide for carbon nanotube (CNT) growth via catalytic chemical vapor deposition (CCVD). Silicon dioxide (SiO 2 ) and tantalum have been deposited as supporting layers before deposition of a thin layer of iron catalyst. Iron nanoparticles were formed after thermal annealing. It was found that densities, size distributions, and morphologies of iron nanoparticles were distinctly different on the two supporting layers. In particular, iron nanoparticles revealed a Volmer-Weber growth mode on SiO 2 and a Stranski-Krastanov mode on tantalum. CCVD growth of CNTs was conducted on iron/tantalum and iron/SiO 2 . CNT growth on SiO 2 exhibited a tip growth mode with a slow growth rate of less than 100 nm/min. In contrast, the growth on tantalum followed a base growth mode with a fast growth rate exceeding 1 μm/min. For comparison, plasma enhanced CVD was also employed for CNT growth on SiO 2 and showed a base growth mode with a growth rate greater than 2 μm/min. The enhanced CNT growth rate on tantalum was attributed to the morphologies of iron nanoparticles in combination with the presence of an iron wetting layer. The CNT growth mode was affected by the adhesion between the catalyst and support as well as CVD process

  4. Formation control of surface marine craft using Lagrange multipliers

    DEFF Research Database (Denmark)

    Ihle, Ivar-Andre F.; Jouffroy, Jerome; Fossen, Thor I.

    We propose a method for constructing control laws for formation control of marine craft using classical tools from analytical mechanics. The control law is based on applying inter-vessel constraint functions which again impose forces on the individual vessels that maintain the given constraints...... on the total system. In this way, a formation can be assembled and stay together when exposed to external forces. A brief comparison with other control designs for a group of marine craft is done. Further, control laws for formation assembling (with dynamic positioning), and formation keeping during...

  5. Formation of Reversible Solid Electrolyte Interface on Graphite Surface from Concentrated Electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Dongping; Tao, Jinhui; Yan, Pengfei; Henderson, Wesley A.; Li, Qiuyan; Shao, Yuyan; Helm, Monte L.; Borodin, Oleg; Graff, Gordon L.; Polzin, Bryant; Wang, Chong-Min; Engelhard, Mark; Zhang, Ji-Guang; De Yoreo, James J.; Liu, Jun; Xiao, Jie

    2017-02-10

    Interfacial phenomena have always been key determinants for the performance of energy storage technologies. The solid electrolyte interfacial (SEI) layer, pervasive on the surfaces of battery electrodes for numerous chemical couples, directly affects the ion transport, charge transfer and lifespan of the entire energy system. Almost all SEI layers, however, are unstable resulting in the continuous consumption of the electrolyte. Typically, this leads to the accumulation of degradation products on/restructuring of the electrode surface and thus increased cell impedance, which largely limits the long-term operation of the electrochemical reactions. Herein, a completely new SEI formation mechanism has been discovered, in which the electrolyte components reversibly self-assemble into a protective surface coating on a graphite electrode upon changing the potential. In contrast to the established wisdom regarding the necessity of employing the solvent ethylene carbonate (EC) to form a protective SEI layer on graphite, a wide range of EC-free electrolytes are demonstrated for the reversible intercalation/deintercalation of Li+ cations within a graphite lattice, thereby providing tremendous flexibility in electrolyte tailoring for battery couples. This novel finding is broadly applicable and provides guidance for how to control interfacial reactions through the relationship between ion aggregation and solvent decomposition at polarized interfaces.

  6. Effect of carbon embedding on the tribological properties of magnetic media surface with and without a perfluoropolyether (PFPE) layer

    International Nuclear Information System (INIS)

    Samad, M Abdul; Yang, H; Bhatia, C S; Sinha, S K

    2011-01-01

    Carbon embedding (≤1 nm) in the top surface of cobalt (∼100 nm) sputtered on a silicon surface is used as a surface modification technique to evaluate the tribological properties with or without an ultra-thin layer of perfluoropolyether (PFPE) lubricant. The carbon embedding is achieved using the filtered cathodic vacuum arc technique at an ion energy of 90 eV. Transport of ions in matter simulations, time-of-flight secondary ion spectroscopy, transmission electron microscopy and x-ray photoelectron spectroscopy (XPS) are used to study the carbon embedding profiles and surface chemical composition. The XPS results show that carbon embedding using the ion energy of 90 eV results in the formation of about 58 ± 6% of tetrahedral (sp 3 ) carbon hybridization. Furthermore, the XPS results also show that the carbon embedding is effective in improving the anti-oxidation resistance of cobalt. Ball-on-disk tribological tests are conducted at a contact pressure of 0.26 GPa on the modified cobalt surface with or without the PFPE layer. It is observed that the average coefficient of friction is reduced considerably from a value of approximately 0.7 to 0.42 after the surface modification. The coefficient of friction is further reduced to ∼0.26 after the deposition of an ultra-thin layer of PFPE over the modified surface, which is lower than a friction coefficient of 0.4 from commercial media. The modified cobalt surface also shows much better wear life than the present day commercial media.

  7. Study on the surface oxidation resistance of uranium metal in the atmosphere of carbon monoxide

    International Nuclear Information System (INIS)

    Wang Xiaolin; Fu Yibei; Xie Renshou

    1999-01-01

    The surface reactions of different layers on uranium metal with carbon monoxide at 25, 80 and 200 degree C are studied by X-ray photoelectron spectroscopy (XPS). The experimental results show that the carbon monoxide is adsorbed on the surface oxide layer of uranium and interacted each other. The content of oxygen in the surface oxide and O/U ratio are decreased with increasing the exposure of carbon monoxide to the surface layer. The effect of reduction on the metal surface is more obviously with a higher temperature and increasing of layer thickness. The investigation indicates the uranium metal has resistance to further oxidation in the atmosphere of carbon monoxide

  8. Influence of thermal treatment on porosity formation on carbon fiber from textile PAN

    Directory of Open Access Journals (Sweden)

    Jossano Saldanha Marcuzzo

    2012-01-01

    Full Text Available Activated carbon fibers (ACFs are known as an excellent adsorbent material due to their particular characteristics such as their high speed adsorption rate and for being easy to handle. The ACFs are commercially manufactured from carbon fibers (CF which receive an additional activation process and can be produced from celluloses, phenolic resin, pitch and Polyacrylonitrile (PAN. In the present work, the oxidized 5.0 dtex textile PAN fiber was carbonized to CFs formation. During the carbonization process in different heating rates, the topographic features changes on fibers were monitored in order to determine the best carbonization condition for CFs production to be used as raw material for ACF. Different heating rates and maximum temperature of treatment were tested and the results indicated that it is possible to produce poorly activated carbon fiber, directly from oxidized textile PAN fiber, by one single step production process.

  9. Influence of thermal treatment on porosity formation on carbon fiber from textile PAN

    Directory of Open Access Journals (Sweden)

    Jossano Saldanha Marcuzzo

    2013-02-01

    Full Text Available Activated carbon fibers (ACFs are known as an excellent adsorbent material due to their particular characteristics such as their high speed adsorption rate and for being easy to handle. The ACFs are commercially manufactured from carbon fibers (CF which receive an additional activation process and can be produced from celluloses, phenolic resin, pitch and Polyacrylonitrile (PAN. In the present work, the oxidized 5.0 dtex textile PAN fiber was carbonized to CFs formation. During the carbonization process in different heating rates, the topographic features changes on fibers were monitored in order to determine the best carbonization condition for CFs production to be used as raw material for ACF. Different heating rates and maximum temperature of treatment were tested and the results indicated that it is possible to produce poorly activated carbon fiber, directly from oxidized textile PAN fiber, by one single step production process.

  10. Carbon ion irradiation induced surface modification of polypropylene

    International Nuclear Information System (INIS)

    Saha, A.; Chakraborty, V.; Dutta, R.K.; Chintalapudi, S.N.

    2001-01-01

    Polypropylene was irradiated with 12 C ions of 3.6 and 5.4 MeV energies in the fluence range of 5x10 13 -5x10 14 ions/cm 2 using 3 MV tandem accelerator. Ion penetration was limited to a few microns and surface modifications were investigated by scanning electron microscopy. At the lowest ion fluence only blister formation of various sizes (1-6 μm) were observed, but at higher fluence (1x10 14 ions/cm 2 ) a three-dimensional network structure was found to form. A gradual degradation in the network structure was observed with further increase in the ion fluence. The dose dependence of the changes on surface morphology of polypropylene is discussed

  11. Carbon ion irradiation induced surface modification of polypropylene

    Energy Technology Data Exchange (ETDEWEB)

    Saha, A. E-mail: abhijit@alpha.iuc.res.in; Chakraborty, V.; Dutta, R.K.; Chintalapudi, S.N

    2001-12-01

    Polypropylene was irradiated with {sup 12}C ions of 3.6 and 5.4 MeV energies in the fluence range of 5x10{sup 13}-5x10{sup 14} ions/cm{sup 2} using 3 MV tandem accelerator. Ion penetration was limited to a few microns and surface modifications were investigated by scanning electron microscopy. At the lowest ion fluence only blister formation of various sizes (1-6 {mu}m) were observed, but at higher fluence (1x10{sup 14} ions/cm{sup 2}) a three-dimensional network structure was found to form. A gradual degradation in the network structure was observed with further increase in the ion fluence. The dose dependence of the changes on surface morphology of polypropylene is discussed.

  12. Effects of Extensive Beetle-Induced Forest Mortality on Aromatic Organic Carbon Loading and Disinfection Byproduct Formation Potential

    Science.gov (United States)

    Brouillard, B.; Mikkelson, K. M.; Dickenson, E.; Sharp, J.

    2015-12-01

    Recent drought and warmer temperatures associated with climate change have caused increased pest-induced forest mortality with impacts on biogeochemical and hydrologic processes. To better understand the seasonal impacts of bark beetle infestation on water quality, samples were collected regularly over two overlapping snow free seasons at surface water intakes of six water treatment facilities in the Rocky Mountain region of Colorado displaying varying levels of bark beetle infestation (high >40%, moderate 20-40%, and low <20%). Organic carbon concentrations were typically 3 to 6 times higher in waters sourced from high beetle-impacted watersheds compared to moderate and low impact watersheds, revealing elevated specific ultraviolet absorbance, fluorescence, and humic-like intensity indicative of elevated aromatic carbon signatures. Accordingly, an increase in disinfection byproduct (DBP) formation potential of 400 to 600% was quantified when contrasted with watersheds containing less tree mortality. Beetle impact exasperated seasonal increases in carbon loading and DBP formation potential following both runoff and precipitation events indicating windows when enhanced water treatment may be utilized by water providers in highly infested regions. Additionally, elevated carbon concentrations throughout the summer and fall along with peaks following precipitation events provide evidence of shifting hydrologic flow paths in areas experiencing high forest mortality from decreased tree water uptake and interception. Collectively, these results demonstrate the need for continued watershed protection and monitoring with a changing climate as the resultant perturbations can have adverse effects on biogeochemistry and water quality in heavily impacted areas.

  13. Kinetics and mechanism of heterogeneous oxidation of sulfur dioxide by ozone on surface of calcium carbonate

    Directory of Open Access Journals (Sweden)

    L. Li

    2006-01-01

    Full Text Available Sulfate particles play a key role in the air quality and the global climate, but the heterogeneous formation mechanism of sulfates on surfaces of atmospheric particles is not well established. Carbonates, which act as a reactive component in mineral dust due to their special chemical properties, may contribute significantly to the sulfate formation by heterogeneous processes. This paper presents a study on the oxidation of SO2 by O3 on CaCO3 particles. Using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS, the formation of sulfite and sulfate on the surface was identified, and the roles of O3 and water in oxidation processes were determined. The results showed that in the presence of O3, SO2can be oxidized to sulfate on the surface of CaCO3 particles. The reaction is first order in SO2 and zero order in O3. The reactive uptake coefficient for SO2 [(0.6–9.8×1014 molecule cm-3] oxidation by O3 [(1.2–12×1014 molecule cm-3] was determined to be (1.4±0.3×10-7 using the BET area as the reactive area and (7.7±1.6×10-4 using the geometric area. A two-stage mechanism that involves adsorption of SO2 followed by O3 oxidation is proposed and the adsorption of SO2 on the CaCO3 surface is the rate-determining step. The proposed mechanism can well explain the experiment results. The atmospheric implications were explored based on a box model calculation. It was found that the heterogeneous reaction might be an important pathway for sulfate formation in the atmosphere.

  14. Investigation of carbon cathode surface before and after the passage of combined dc vacuum arc with superimposed high-current arc pulses

    International Nuclear Information System (INIS)

    Zavaleyev, V.; Walkowicz, J.; Moszynski, D.

    2016-01-01

    The paper presents the results of studies of carbon cathode surface before and after the passage of the combined DC vacuum-arc with superimposed high-current arc pulses. Investigations of surface morphology of carbon cathode showed, that secondary nuclei of high-density are formed after passing of the combined DC-pulse vacuum-arc, which results in the formation of a globular structures. The phase structure analysis by Raman spectroscopy showed that even at a minimum operation time (5 s) of the combined DC-pulse vacuum-arc broadening of the peaks 1355 and 1583 cm-1 occurs, which means that the carbon cathode surface undergo phase transformation. Results obtained by XPS spectroscopy demonstrate that the globular structures formed on the cathode surface are composed of sp 3 -bonded carbon atoms and carbon-oxygen bonds.

  15. COMPOSITION AND METHOD FOR CONTROLLING MICROBIAL ADHESION AND BIOFILM FORMATION OF SURFACES

    DEFF Research Database (Denmark)

    2003-01-01

    The present invention describes how coating of surfaces with an extract, particularly a fish extract, can significantly reduce microbial adhesion, attachment, colonization and biofilm formation on surfaces. Such reduction of microbial adherence, attachment and colonization will be applicable...

  16. Formation of secondary organic aerosol coating on black carbon particles near vehicular emissions

    Science.gov (United States)

    Lee, Alex K. Y.; Chen, Chia-Li; Liu, Jun; Price, Derek J.; Betha, Raghu; Russell, Lynn M.; Zhang, Xiaolu; Cappa, Christopher D.

    2017-12-01

    Black carbon (BC) emitted from incomplete combustion can result in significant impacts on air quality and climate. Understanding the mixing state of ambient BC and the chemical characteristics of its associated coatings is particularly important to evaluate BC fate and environmental impacts. In this study, we investigate the formation of organic coatings on BC particles in an urban environment (Fontana, California) under hot and dry conditions using a soot-particle aerosol mass spectrometer (SP-AMS). The SP-AMS was operated in a configuration that can exclusively detect refractory BC (rBC) particles and their coatings. Using the -log(NOx / NOy) ratio as a proxy for photochemical age of air masses, substantial formation of secondary organic aerosol (SOA) coatings on rBC particles was observed due to active photochemistry in the afternoon, whereas primary organic aerosol (POA) components were strongly associated with rBC from fresh vehicular emissions in the morning rush hours. There is also evidence that cooking-related organic aerosols were externally mixed from rBC. Positive matrix factorization and elemental analysis illustrate that most of the observed SOA coatings were freshly formed, providing an opportunity to examine SOA coating formation on rBCs near vehicular emissions. Approximately 7-20 wt % of secondary organic and inorganic species were estimated to be internally mixed with rBC on average, implying that rBC is unlikely the major condensation sink of SOA in this study. Comparison of our results to a co-located standard high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) measurement suggests that at least a portion of SOA materials condensed on rBC surfaces were chemically different from oxygenated organic aerosol (OOA) particles that were externally mixed with rBC, although they could both be generated from local photochemistry.

  17. Formation of a silicon terminated (100) diamond surface

    International Nuclear Information System (INIS)

    Schenk, Alex; Sear, Michael; Pakes, Chris; Tadich, Anton; O'Donnell, Kane M.; Ley, Lothar; Stacey, Alastair

    2015-01-01

    We report the preparation of an ordered silicon terminated diamond (100) surface with a two domain 3 × 1 reconstruction as determined by low energy electron diffraction. Based on the dimensions of the surface unit cell and on chemical information provided by core level photoemission spectra, a model for the structure is proposed. The termination should provide a homogeneous, nuclear, and electron spin-free surface for the development of future near-surface diamond quantum device architectures

  18. Carbon out-diffusion mechanism for direct graphene growth on a silicon surface

    International Nuclear Information System (INIS)

    Kim, Byung-Sung; Lee, Jong Woon; Jang, Yamujin; Choi, Soon Hyung; Cha, Seung Nam; Sohn, Jung Inn; Kim, Jong Min; Joo, Won-Jae; Hwang, Sungwoo; Whang, Dongmok

    2015-01-01

    Direct growth of graphene on silicon (Si) through chemical vapor deposition has predominantly focused on surface-mediated processes due to the low carbon (C) solubility in Si. However, a considerable quantity of C atoms was incorporated in Si and formed Si 1−x C x alloy with a reduced lattice dimension even in the initial stage of direct graphene growth. Subsequent high temperature annealing promoted active C out-diffusion, resulting in the formation of a graphitic layer on the Si surface. Furthermore, the significantly low thermal conductivity of the Si 1−x C x alloy shows that the incorporated C atoms affect the properties of a semiconductor adjacent to the graphene. These findings provide a key guideline for controlling desirable properties of graphene and designing hybrid semiconductor/graphene architectures for various applications

  19. Surface and Adsorption Properties of Activated Carbon Fabric Prepared from Cellulosic Polymer: Mixed Activation Method

    Energy Technology Data Exchange (ETDEWEB)

    Bhati, Surendra; Mahur, J. S.; Choubey, O. N. [Barkatullah Univ., Bhopal (India); Dixit, Mahur Savita [Maulana Azad National Institute of Technology, Bhopla (India)

    2013-02-15

    In this study, activated carbon fabric was prepared from a cellulose-based polymer (viscose rayon) via a combination of physical and chemical activation (mixed activation) processes by means of CO{sub 2} as a gasifying agent and surface and adsorption properties were evaluated. Experiments were performed to investigate the consequence of activation temperature (750, 800, 850 and 925 .deg. C), activation time (15, 30, 45 and 60 minutes) and CO{sub 2} flow rate (100, 200, 300 and 400 mL/min) on the surface and adsorption properties of ACF. The nitrogen adsorption isotherm at 77 K was measured and used for the determination of surface area, total pore volume, micropore volume, mesopore volume and pore size distribution using BET, t-plot, DR, BJH and DFT methods, respectively. It was observed that BET surface area and TPV increase with rising activation temperature and time due to the formation of new pores and the alteration of micropores into mesopores. It was also found that activation temperature dominantly affects the surface properties of ACF. The adsorption of iodine and CCl{sub 4} onto ACF was investigated and both were found to correlate with surface area.

  20. Surface and Adsorption Properties of Activated Carbon Fabric Prepared from Cellulosic Polymer: Mixed Activation Method

    International Nuclear Information System (INIS)

    Bhati, Surendra; Mahur, J. S.; Choubey, O. N.; Dixit, Mahur Savita

    2013-01-01

    In this study, activated carbon fabric was prepared from a cellulose-based polymer (viscose rayon) via a combination of physical and chemical activation (mixed activation) processes by means of CO 2 as a gasifying agent and surface and adsorption properties were evaluated. Experiments were performed to investigate the consequence of activation temperature (750, 800, 850 and 925 .deg. C), activation time (15, 30, 45 and 60 minutes) and CO 2 flow rate (100, 200, 300 and 400 mL/min) on the surface and adsorption properties of ACF. The nitrogen adsorption isotherm at 77 K was measured and used for the determination of surface area, total pore volume, micropore volume, mesopore volume and pore size distribution using BET, t-plot, DR, BJH and DFT methods, respectively. It was observed that BET surface area and TPV increase with rising activation temperature and time due to the formation of new pores and the alteration of micropores into mesopores. It was also found that activation temperature dominantly affects the surface properties of ACF. The adsorption of iodine and CCl 4 onto ACF was investigated and both were found to correlate with surface area

  1. The Impact of Sonication on the Surface Quality of Single-Walled Carbon Nanotubes.

    Science.gov (United States)

    Koh, Byumseok; Cheng, Wei

    2015-08-01

    Sonication process is regularly adopted for dispersing single-walled carbon nanotubes (SWCNTs) in an aqueous medium. This can be achieved by either covalent functionalization of SWCNTs with strong acid or by noncovalent functionalization using dispersants that adsorb onto the surface of SWCNTs during dispersion. Because the dispersion process is usually performed using sonication, unintentional free radical formation during sonication process may induce covalent modification of SWCNT surface. Herein, we have systematically investigated the status of SWCNT surface modification under various sonication conditions using Raman spectroscopy. Comparing ID /IG (Raman intensities between D and G bands) ratio of SWCNTs under various sonication conditions suggests that typical sonication conditions (1-6 h bath sonication with sonication power between 3 and 80 W) in aqueous media do not induce covalent modification of SWCNT surface. In addition, we confirm that SWCNT dispersion with single-stranded DNA (ssDNA) involves noncovalent adsorption of ssDNA onto the surface of SWCNTs, but not covalent linkage between ssDNA and SWCNT surface. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  2. Surface chemistry of carbon removal from indium tin oxide by base and plasma treatment, with implications on hydroxyl termination

    International Nuclear Information System (INIS)

    Chaney, John A.; Koh, Sharon E.; Dulcey, Charles S.; Pehrsson, Pehr E.

    2003-01-01

    The surface chemistry of carbon removal from indium tin oxide (ITO) has been investigated with Auger electron spectroscopy (AES), high-resolution electron energy loss spectroscopy (HREELS), and high-resolution energy loss spectroscopy (HR-ELS). A vibrating Kelvin probe (KP) was used to monitor the work function (PHI) of ITO after cleaning, either by base-cleaning with alcoholic-KOH or by O 2 plasma-cleaning. Base-cleaning lowered PHI ITO as seen in the KP analysis, whereas plasma-cleaning slightly increased PHI ITO by an oxidative process. The degree of PHI ITO depression by base-cleaning was seen to depend on the initial surface, but the PHI depression itself was nonreductive to the ITO, as seen in the In-MNN AES lineshape. The nonreductive depression of PHI ITO by base-cleaning was further supported by a constant charge carrier density, as estimated from the HR-ELS. Base-cleaning was slightly more effective than the oxygen plasma in removing carbon from the ITO surface. However, base-cleaning preferentially removed graphitic carbon while leaving significant hydrocarbon contaminants, as determined by vibrational analysis with HREELS. All other ITO surfaces retained a significant carbon and hydrocarbon contamination as evidenced by AES and HREELS. There was little evidence of the formation of surface hydroxyl species, as expected for such an inherently contaminated surface as ITO

  3. Cryogenic cave carbonates from the Cold Wind Cave, Nízke Tatry Mountains, Slovakia: Extending the age range of cryogenic cave carbonate formation to the Saalian

    Directory of Open Access Journals (Sweden)

    Zak K.

    2009-07-01

    Full Text Available Cold Wind Cave, located at elevations ranging between 1,600 and 1,700 m a. s. l. in the main range of the Nízke Tatry Mountains(Slovakia, is linked in origin with the adjacent Dead Bats Cave. Together, these caves form a major cave system located within anarrow tectonic slice of Triassic sediments. Both caves have undergone complex multiphase development. A system of sub-horizontalcave levels characterized by large, tunnel-like corridors was formed during the Tertiary, when elevation differences surroundingthe cave were less pronounced than today. The central part of the Nízke Tatry Mountains, together with the cave systems, wasuplifted during the Neogene and Lower Pleistocene, which changed the drainage pattern of the area completely. The formation ofnumerous steep-sloped vadose channels and widespread cave roof frost shattering characterized cave development throughout theQuaternary.In the Cold Wind Cave, extensive accumulations of loose, morphologically variable crystal aggregates of secondary cave carbonateranging in size between less than 1 mm to about 35 mm was found on the surface of fallen limestone blocks. Based on the C andO stable isotope compositions of the carbonate (δ13C: 0.72 to 6.34 ‰, δ18O: –22.61 to –13.68 ‰ V-PDB and the negative relationbetween δ13C and δ18O, the carbonate crystal aggregates are interpreted as being cryogenic cave carbonate (CCC. Publishedmodels suggest the formation of CCC in slowly freezing water pools, probably on the surface of cave ice, most probably duringtransitions from stadials to interstadials. Though the formation of these carbonates is likely one of the youngest events in thesequence of formation of cave sediments of the studied caves, the 230Th/234U ages of three samples (79.7±2.3, 104.0±2.9, and180.0±6.3 ka are the oldest so far obtained for CCC in Central Europe. This is the first description of CCC formation in one caveduring two glacial periods (Saalian and Weichselian.

  4. Diamond-like carbon coating under oleic acid lubrication: Evidence for graphene oxide formation in superlow friction

    Science.gov (United States)

    de Barros Bouchet, Maria Isabel; Martin, Jean Michel; Avila, José; Kano, Makoto; Yoshida, Kentaro; Tsuruda, Takeshi; Bai, Shandan; Higuchi, Yuji; Ozawa, Nobuki; Kubo, Momoji; Asensio, Maria C.

    2017-04-01

    The achievement of the superlubricity regime, with a friction coefficient below 0.01, is the Holy Grail of many tribological applications, with the potential to have a remarkable impact on economic and environmental issues. Based on a combined high-resolution photoemission and soft X-ray absorption study, we report that superlubricity can be realized for engineering applications in bearing steel coated with ultra-smooth tetrahedral amorphous carbon (ta-C) under oleic acid lubrication. The results show that tribochemical reactions promoted by the oil lubrication generate strong structural changes in the carbon hybridization of the ta-C hydrogen-free carbon, with initially high sp3 content. Interestingly, the macroscopic superlow friction regime of moving mechanical assemblies coated with ta-C can be attributed to a few partially oxidized graphene-like sheets, with a thickness of not more than 1 nm, formed at the surface inside the wear scar. The sp2 planar carbon and oxygen-derived species are the hallmark of these mesoscopic surface structures created on top of colliding asperities as a result of the tribochemical reactions induced by the oleic acid lubrication. Atomistic simulations elucidate the tribo-formation of such graphene-like structures, providing the link between the overall atomistic mechanism and the macroscopic experimental observations of green superlubricity in the investigated ta-C/oleic acid tribological systems.

  5. Effect of Heat Treatment on the Surface Properties of Activated Carbons

    Directory of Open Access Journals (Sweden)

    Meriem Belhachemi

    2011-01-01

    Full Text Available This work reports the effect of heat treatment on the porosity and surface chemistry of two series of activated carbons prepared from a local agricultural biomass material, date pits, by physical activation with carbon dioxide and steam. Both series samples were oxidized with nitric acid and subsequently heat treated under N2 at 973 K in order to study the effect of these treatments in porosity and surface functional groups of activated carbons. When the activated carbons were heat treated after oxidation the surface area and the pore volume increase for both activated carbons prepared by CO2 and steam activations. However the amount of surface oxygen complexes decreases, the samples keep the most stable oxygen surface groups evolved as CO by temperature-programmed desorption experiments at high temperature. The results show that date pits can be used as precursors to produce activated carbons with a well developed porosity and tailored oxygen surface groups.

  6. Renewable hydrogen: carbon formation on Ni and Ru catalysts during ethanol steam-reforming

    DEFF Research Database (Denmark)

    Rass-Hansen, Jeppe; Christensen, Christina Hviid; Sehested, J.

    2007-01-01

    for the production of hydrogen is investigated, along with quantitative and qualitative determinations of carbon formation on the catalysts by TPO and TEM experiments. A Ru/ MgAl2O4 catalyst, a Ni/MgAl2O4 catalyst as well as Ag-and K-promoted Ni/ MgAl2O4 catalysts were studied. The operating temperature was between...... addition was a rapid deactivation of the catalyst due to an enhanced gum carbon formation on the Ni crystals. Contrary to this, the effect of K addition was a prolonged resistance against carbon formation and therefore against deactivation. The Ru catalyst operates better than all the Ni catalysts...

  7. Dynamics of C2 formation in laser-produced carbon plasma in helium environment

    International Nuclear Information System (INIS)

    Al-Shboul, K. F.; Harilal, S. S.; Hassanein, A.; Polek, M.

    2011-01-01

    We investigated the role of helium ambient gas on the dynamics of C 2 species formation in laser-produced carbon plasma. The plasma was produced by focusing 1064 nm pulses from an Nd:YAG laser onto a carbon target. The emission from the C 2 species was studied using optical emission spectroscopy, and spectrally resolved and integrated fast imaging. Our results indicate that the formation of C 2 in the plasma plume is strongly affected by the pressure of the He gas. In vacuum, the C 2 emission zone was located near the target and C 2 intensity oscillations were observed both in axial and radial directions with increasing the He pressure. The oscillations in C 2 intensity at higher pressures in the expanding plume could be caused by various formation zones of carbon dimers.

  8. Phenol removal onto novel activated carbons made from lignocellulosic precursors: Influence of surface properties

    OpenAIRE

    Valente Nabais, Joao; Gomes, Jose; Suhas, Suhas; Carrott, Peter; Laginhas, Carlos; Roman, Silvia

    2009-01-01

    The adsorption of phenol from dilute aqueous solutions onto new activated carbons (AC) was studied. The novel activated carbon was produced from lignocellulosic (LC) precursors of rapeseed and kenaf. Samples oxidised with nitric acid in liquid phasewere also studied. The results have shown the significant potential of rapeseed and kenaf for the activated carbon production. The activated carbons produced by carbon dioxide activation were mainly microporous with BET apparent surface...

  9. Fabrication of mesoporous and high specific surface area lanthanum carbide-carbon nanotube composites

    International Nuclear Information System (INIS)

    Biasetto, L.; Carturan, S.; Maggioni, G.; Zanonato, P.; Bernardo, P. Di; Colombo, P.; Andrighetto, A.; Prete, G.

    2009-01-01

    Mesoporous lanthanum carbide-carbon nanotube composites were produced by means of carbothermal reaction of lanthanum oxide, graphite and multi-walled carbon nanotube mixtures under high vacuum. Residual gas analysis revealed the higher reactivity of lanthanum oxide towards carbon nanotubes compared to graphite. After sintering, the composites revealed a specific surface area increasing with the amount of carbon nanotubes introduced. The meso-porosity of carbon nanotubes was maintained after thermal treatment.

  10. FORMATION OF ANTIBACTERIAL EFFECT ON CERAMIC TILE SURFACES

    Directory of Open Access Journals (Sweden)

    Selçuk ÖZCAN

    2017-03-01

    Full Text Available Biocidal antimicrobial molecular barrier (BAMB solutions are known to provide antimicrobial effect on the surfaces in industrial applications. However, there has been a lack of scientific reports about the subject in the literature. In this study, in order to impart an antimicrobial surface property on ceramic surfaces, a BAMB solution was applied on gloss fired ceramic wall tile substrates and the surface antimicrobial activity results were compared with that of plain wall tiles (without BAMB application. The ceramic surfaces were cleaned, and stove dried at120°C prior to spray coating with a BAMB solution. The coated substrates were dried in the ambient. The intactness of the coatings was checked with the bromophenol blue test. The microstructural and molecular characterization of the BAMB coated surfaces were carried out with SEM imaging and surface FTIR, respectively. The antimicrobial activity tests of the surfaces were conducted according to ASTM E2180-07 (Standard Test Method for Determining the Activity of Incorporated Antimicrobial Agent in Polymeric or Hydrophobic Materials. The microorganisms used were Staphylococcus aureus (ATCC 6538 and Pseudomonas aeruginosa (ATCC 15442 bacteria. The BAMB coated surfaces showed less flocculent bacterial growth in comparison to uncoated ceramic surfaces leading to the conclusion that the BAMB improved the antimicrobial property.

  11. Calculations of oxide formation on low-index Cu surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lian, Xin; Liu, Renlong, E-mail: lrl@cqu.edu.cn, E-mail: henkelman@utexas.edu [College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030 (China); Xiao, Penghao; Yang, Sheng-Che; Henkelman, Graeme, E-mail: lrl@cqu.edu.cn, E-mail: henkelman@utexas.edu [Department of Chemistry and the Institute for Computational and Engineering Sciences, University of Texas at Austin, Austin, Texas 78712-0165 (United States)

    2016-07-28

    Density-functional theory is used to evaluate the mechanism of copper surface oxidation. Reaction pathways of O{sub 2} dissociation on the surface and oxidation of the sub-surface are found on the Cu(100), Cu(110), and Cu(111) facets. At low oxygen coverage, all three surfaces dissociate O{sub 2} spontaneously. As oxygen accumulates on the surfaces, O{sub 2} dissociation becomes more difficult. A bottleneck to further oxidation occurs when the surfaces are saturated with oxygen. The barriers for O{sub 2} dissociation on the O-saturated Cu(100)-c(2×2)-0.5 monolayer (ML) and Cu(100) missing-row structures are 0.97 eV and 0.75 eV, respectively; significantly lower than those have been reported previously. Oxidation of Cu(110)-c(6×2), the most stable (110) surface oxide, has a barrier of 0.72 eV. As the reconstructions grow from step edges, clean Cu(110) surfaces can dissociatively adsorb oxygen until the surface Cu atoms are saturated. After slight rearrangements, these surface areas form a “1 ML” oxide structure which has not been reported in the literature. The barrier for further oxidation of this “1 ML” phase is only 0.31 eV. Finally the oxidized Cu(111) surface has a relatively low reaction energy barrier for O{sub 2} dissociation, even at high oxygen coverage, and allows for facile oxidation of the subsurface by fast O diffusion through the surface oxide. The kinetic mechanisms found provide a qualitative explanation of the observed oxidation of the low-index Cu surfaces.

  12. Buffering dissociation/formation reaction of biogenic calcium carbonate.

    Science.gov (United States)

    Ichikawa, Kazuhiko

    2007-01-01

    The oscillating stability of coral reef seawater pH has been maintained at around physiological pH values over the past 300 years (Pelejero et al., 2005). The stability mechanism of its pH has been interpreted in terms of the buffering dissolution/formation reaction of CaCO(3) as well as the proton consumption/generation reaction in CaCO(3)-saturated water. Here the pH-dependent solubility product [HCO(3)(-)][Ca(2+)] has been derived on the basis of the actual pH-dependent reactions for the atmospheric CO(2)/CO(2 (aq.))/HCO(3)(-)/CO(3)(2-)/Ca(2+)/CaCO(3) system. Overbasic pH peaks appeared between pH approximately 8 and approximately 9.5 during sodium hydroxide titration, as a result of simultaneous CaCO(3) formation and proton generation. The spontaneous and prompt water pH recovery from the acidic to the physiological range has been confirmed by the observation of acid/base time evolution, because of simultaneous CaCO(3) dissolution and proton consumption. The dissolution/formation of CaCO(3) in water at pH 7.5-9 does not take place without a proton consumption/generation reaction, or a buffering chemical reaction of HCO(3)(-)+Ca(2+)right arrow over left arrowCaCO(3)+H(+). SEM images of the CaCO(3) fragments showed that the acid water ate away at the CaCO(3) formed at physiological pH values. Natural coral reefs can thus recover the physiological pH levels of seawater from the acidic range through partial dissolution of their own skeletons.

  13. Effect of Carbonates and Bivalent Cations and Their Relationships with Soil Organic Matter from the View Point of Aggregate Formation

    Directory of Open Access Journals (Sweden)

    Vladimír Šimanský

    2014-12-01

    Full Text Available The effect of carbonates on soil structure has not been sufficiently studied yet, despite the fact that in the literature their positive impact is mentioned mostly. Carbonates are the source of bivalent cations in soil solution and may be involved in stabilization of the aggregates, because negatively charged organic materials can be adsorbed onto the surface of clay by bivalent or polyvalent cations. We studied the effect of carbonates and bivalent cations and their relationships with soil organic matter (SOM from the point of view of aggregate formation. The studies were carried out in several fields located on loamy Calcaric Chernozem, loamy Haplic and Mollic Fluvisols. The results showed that between exchangeable Mg2+ and water-stable macro-aggregates (WSAma in size fractions >2 mm, positive correlations were found; however, the content of Mg2+ negative correlated with the contents of WSAma in 2 mm; however, between SBC as well as CEC and smaller size fractions of WSAma >1 mm and WSAmi negative correlations were observed. Statistically significant negative correlations were observed between SOM content in WSA and carbonate content, and this effect was stronger in relation to the labile carbon. There were also positive correlations between SOM in WSA and SBC and CEC found if all loamy soils were assessed together.

  14. Effects of mineral additives on biochar formation: carbon retention, stability, and properties.

    Science.gov (United States)

    Li, Feiyue; Cao, Xinde; Zhao, Ling; Wang, Jianfei; Ding, Zhenliang

    2014-10-07

    Biochar is being recognized as a promising tool for long-term carbon sequestration, and biochar with high carbon retention and strong stability is supposed to be explored for that purpose. In this study, three minerals, including kaolin, calcite (CaCO3), and calcium dihydrogen phosphate [Ca(H2PO4)2], were added to rice straw feedstock at the ratio of 20% (w/w) for biochar formation through pyrolysis treatment, aiming to improve carbon retention and stabilization in biochar. Kaolin and CaCO3 had little effect on the carbon retention, whereas Ca(H2PO4)2 increased the carbon retention by up to 29% compared to untreated biochar. Although the carbon loss from the kaolin-modified biochar with hydrogen peroxide oxidation was enhanced, CaCO3 and Ca(H2PO4)2 modification reduced the carbon loss by 18.6 and 58.5%, respectively. Moreover, all three minerals reduced carbon loss of biochar with potassium dichromate oxidation from 0.3 to 38.8%. The microbial mineralization as CO2 emission in all three modified biochars was reduced by 22.2-88.7% under aerobic incubation and 5-61% under anaerobic incubation. Enhanced carbon retention and stability of biochar with mineral treatment might be caused by the enhanced formation of aromatic C, which was evidenced by cross-polarization magic angle spinning (13)C nuclear magnetic resonance spectra and Fourier transform infrared spectroscopy analysis. Our results indicated that the three minerals, especially Ca(H2PO4)2, were effective in increasing carbon retention and strengthening biochar stabilization, which provided a novel idea that people could explore and produce the designated biochar with high carbon sequestration capacity and stability.

  15. Fluctuation-Induced Pattern Formation in a Surface Reaction

    DEFF Research Database (Denmark)

    Starke, Jens; Reichert, Christian; Eiswirth, Markus

    2006-01-01

    Spontaneous nucleation, pulse formation, and propagation failure have been observed experimentally in CO oxidation on Pt(110) at intermediate pressures ($\\approx 10^{-2}$mbar). This phenomenon can be reproduced with a stochastic model which includes temperature effects. Nucleation occurs randomly...... due to fluctuations in the reaction processes, whereas the subsequent damping out essentially follows the deterministic path. Conditions for the occurence of stochastic effects in the pattern formation during CO oxidation on Pt are discussed....

  16. The effect of brushing with nano calcium carbonate and calcium carbonate toothpaste on the surface roughness of nano-ionomer

    Science.gov (United States)

    Anisja, D. H.; Indrani, D. J.; Herda, E.

    2017-08-01

    Nanotechnology developments in dentistry have resulted in the development of nano-ionomer, a new restorative material. The surface roughness of restorative materials can increase bacteria adhesion and lead to poor oral hygiene. Abrasive agents in toothpaste can alter tooth and restorative material surfaces. The aim of this study is to identify the effect of brushing with nano calcium carbonate, and calcium carbonate toothpaste on surface roughness of nano-ionomer. Eighteen nano-ionomer specimens were brushed with Aquabidest (doubledistilled water), nano calcium carbonate and calcium carbonate toothpaste. Brushing lasted 30 minutes, and the roughness value (Ra) was measured after each 10 minute segment using a surface roughness tester. The data was analyzed using repeated ANOVA and one-way ANOVA test. The value of nano-ionomer surface roughness increased significantly (p<0.05) after 20 minutes of brushing with the nano calcium carbonate toothpaste. Brushing with calcium carbonate toothpaste leaves nano-ionomer surfaces more rugged than brushing with nano calcium carbonate toothpaste.

  17. Surface modified carbon nanoparticle papers and applications on polymer composites

    Science.gov (United States)

    Ouyang, Xilian

    Free-standing paper like materials are usually employed as protective layers, chemical filters, components of electrical batteries or supercapacitors, adhesive layers, and electronic or optoelectric components. Free-standing papers made from carbon nanoparticles have drawn increased interest because they have a variety of superior chemical and physical characteristics, such as light weight, high intrinsic mechanical properties, and extraordinary high electrical conductivity. Nanopapers fabricated from 1- D shape carbon nanofibers (CNFs) and carbon nanotubes (CNTs) are promising reinforcing materials for polymer composites, because the highly porous CNF and CNT nanopapers (porosity ˜80% and ˜70% respectively) can be impregnated with matrix polymers. In the first part of this work, polyaniline (PANI) was used to functionalize the surface of CNFs, and the resultant carbon nanopapers presented impressive mechanical strength and electrical conductivity that it could be used in the in-mold coating (IMC)/ injection molding process to achieve high electromagnetic interference (EMI) shielding effectiveness. Aniline modified (AF) CNT nanopapers were used as a 3D network in gas separation membranes. The resultant composite membranes demonstrated better and stable CO2 permeance and CO 2/H2 selectivity in a high temperature (107°C) and high pressure (15-30 atm) gas separation process, not achievable by conventional polymer membranes. In the second part, we demonstrated that 2-D graphene (GP) or graphene oxide (GO) nanosheets could be tightly packed into a film which was impermeable to most gases and liquids. GP or GO nanopapers could be coated on polymer composites. In order to achieve well-dispersed single-layer graphene in aqueous medium, we developed a facile approach to synthesize functional GP bearing benzenesulfonic acid groups which allow the preparation of nanopapers by water based assembly. With the optimized processing conditions, our best GP nanopapers could reach

  18. MODELING OF QUALITY FORMATION OF PIG IRON BILLET SURFACE AT WIRE BRUSH MILLING

    Directory of Open Access Journals (Sweden)

    I. L. Barshaj

    2009-01-01

    Full Text Available Formation of topography, geometrical structure and micro-hardness of pig iron billet surface is considered in the paper. Mathematical models pertaining to formation of the above-mentioned characteristics of surface quality according to parameters of machining regime have been developed on the basis of the executed investigations.

  19. Multiply Surface-Functionalized Nanoporous Carbon for Vehicular Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifer, Peter [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics; Gillespie, Andrew [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics; Stalla, David [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics; Dohnke, Elmar [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics

    2017-02-20

    The purpose of the project “Multiply Surface-Functionalized Nanoporous Carbon for Vehicular Hydrogen Storage” is the development of materials that store hydrogen (H2) by adsorption in quantities and at conditions that outperform current compressed-gas H2 storage systems for electric power generation from hydrogen fuel cells (HFCs). Prominent areas of interest for HFCs are light-duty vehicles (“hydrogen cars”) and replacement of batteries with HFC systems in a wide spectrum of applications, ranging from forklifts to unmanned areal vehicles to portable power sources. State-of-the-art compressed H2 tanks operate at pressures between 350 and 700 bar at ambient temperature and store 3-4 percent of H2 by weight (wt%) and less than 25 grams of H2 per liter (g/L) of tank volume. Thus, the purpose of the project is to engineer adsorbents that achieve storage capacities better than compressed H2 at pressures less than 350 bar. Adsorption holds H2 molecules as a high-density film on the surface of a solid at low pressure, by virtue of attractive surface-gas interactions. At a given pressure, the density of the adsorbed film is the higher the stronger the binding of the molecules to the surface is (high binding energies). Thus, critical for high storage capacities are high surface areas, high binding energies, and low void fractions (high void fractions, such as in interstitial space between adsorbent particles, “waste” storage volume by holding hydrogen as non-adsorbed gas). Coexistence of high surface area and low void fraction makes the ideal adsorbent a nanoporous monolith, with pores wide enough to hold high-density hydrogen films, narrow enough to minimize storage as non-adsorbed gas, and thin walls between pores to minimize the volume occupied by solid instead of hydrogen. A monolith can be machined to fit into a rectangular tank (low pressure, conformable tank), cylindrical tank

  20. XPS study on the surface reaction of uranium metal with carbon monoxide at 200 degree C

    International Nuclear Information System (INIS)

    Wang Xiaoling; Fu Yibei; Xie Renshou; Huang Ruiliang

    1996-12-01

    The surface reaction of uranium metal with carbon monoxide at 200 degree C has been studied by X-ray photoelectron spectroscopy (XPS). The carbon monoxide adsorption on the surface oxide layer resulted in U4f peak shifting to the lower binding energy and the content of oxygen in the oxide is decreased. O/U radio decreases with increasing the exposure of carbon monoxide to the surface layer. The investigation indicated the surface layer of uranium metal was further reduced in the atmosphere of carbon monoxide at high temperature. (3 refs., 5 figs.)

  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. Investigations of carbon diffusion and carbide formation in nickel-based alloys

    International Nuclear Information System (INIS)

    Schulten, R.; Bongartz, K.; Quadakkers, W.J.; Schuster, H.; Nickel, H.

    1989-11-01

    The present thesis describes the carburization behaviour of nickel based alloys in heavily carburizing environments. The mechanisms of carbon diffusion and carbide precipitation in NiCr alloys with and without ternary additions of iron, cobalt or molybdenum have been investigated. Using the results of carburization experiments, a mathematical model which describes carbon diffusion and carbide formation, was developed. The simulation of the carburization process was carried out by an iterative calculation of the local thermodynamic equilibrium in the alloy. An accurate description of the carbon profiles as a function of time became possible by using a finite-difference calculation. (orig.) [de

  3. Biogeochemical processes controlling authigenic carbonate formation within the sediment column from the Okinawa Trough

    Science.gov (United States)

    Li, Jiwei; Peng, Xiaotong; Bai, Shijie; Chen, Zhiyan; Van Nostrand, Joy D.

    2018-02-01

    Authigenic carbonates are one type of conspicuous manifestation in seep environments that can provide long-term archives of past seepage activity and methane cycling in the oceans. Comprehensive investigations of the microbial community functional structure and their roles in the process of carbonate formation are, however, lacking. In this study, the mineralogical, geochemical, and microbial functional composition were examined in seep carbonate deposits collected from the west slope of the northern section of the Okinawa Trough (OT). The aim of this work was to explore the correspondence between the mineralogical phases and microbial metabolism during carbonate deposit formation. The mineralogical analyses indicated that authigenic carbonate minerals (aragonite, magnesium-rich calcite, dolomite, ankerite and siderite) and iron-bearing minerals (limonite, chlorite, and biotite) were present in these carbonate samples. The carbon and oxygen isotopic values of the carbonate samples varied between -51.1‰ to -4.7‰ and -4.8‰ to 3.7‰, respectively. A negative linear correlation between carbon and oxygen isotopic compositions was found, indicating a mixture of methane-derived diagenetic (low δ13C/high 18O) carbonates and detrital origin (high δ13C/low 18O) carbonates at the OT. GeoChip analyses suggested that various metabolic activities of microorganisms, including methanogenesis, methane oxidation, sulfite oxidation, sulfate reduction, and metal biotransformations, all occurred during the formation process. On the basis of these findings, the following model for the methane cycle and seep carbonate deposit formation in the sediment column at the OT is proposed: (1) in the upper oxidizing zone, aerobic methane oxidation was the main way of methane consumption; (2) in the sulfate methane transition zone, sulfate-dependent AOM (anaerobic oxidation of methane) consumes methane, and authigenic minerals such as aragonite, magnesium-calcite, and sulfide minerals

  4. Possible Roles of Fluoride and Carbonate in Biochemical Carbonated Apatite Formation

    Science.gov (United States)

    Meouch, Orysia; Omelon, Sidney

    2016-04-01

    Marine phosphorites are predominantly composed of carbonated fluorapatite (CFA = Ca10-a-b-cNaaMgb(PO4)6-x(CO3)x-y-z(CO3.F)y(SO4)zF2, where x=y+a+2c, and c represents the number of Ca vacancies, with a P2O5 content that ranges from 18-40 %. Sulphur-oxidizing bacteria of the Beggiatoa genus concentration phosphorous as intracellular polyphosphate ((PO3-)n) which is depolymerized into inorganic orthophosphate (Pi). Consequently, an increase in pore water Pi concentration favours carbonated apatite precipitation. The carbonate and fluoride that is characteristic of phosphorite CFA is also located in the vertebrate skeleton. This similarity suggests a biochemical pathway for CFA precipitation. Preliminary Raman spectroscopy and powder x-ray diffraction results that suggest a role for fluoride, and possibly carbonate, in the biochemical depolymerisation of polyphosphates with alkaline phosphatase will be presented.

  5. Formation mechanism of a silicon carbide coating for a reinforced carbon-carbon composite

    Science.gov (United States)

    Rogers, D. C.; Shuford, D. M.; Mueller, J. I.

    1975-01-01

    Results are presented for a study to determine the mechanisms involved in a high-temperature pack cementation process which provides a silicon carbide coating on a carbon-carbon composite. The process and materials used are physically and chemically analyzed. Possible reactions are evaluated using the results of these analytical data. The coating is believed to develop in two stages. The first is a liquid controlled phase process in which silicon carbide is formed due to reactions between molten silicon metal and the carbon. The second stage is a vapor transport controlled reaction in which silicon vapors react with the carbon. There is very little volume change associated with the coating process. The original thickness changes by less than 0.7%. This indicates that the coating process is one of reactive penetration. The coating thickness can be increased or decreased by varying the furnace cycle process time and/or temperature to provide a wide range of coating thicknesses.

  6. Nanopattern formation using localized plasma for growth of single-standing carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Javadi, Mohammad; Abdi, Yaser, E-mail: y.abdi@ut.ac.ir [University of Tehran, Nanophysics Research Laboratory, Department of Physics (Iran, Islamic Republic of)

    2017-01-15

    We report a novel method for formation of self-organized single-standing carbon nanotubes by customizing a plasma-based process. The growth of carbon nanotubes by plasma-enhanced chemical vapor deposition provides suitable grounds to utilize plasma–solid interactions for nanopatterning. The bulk plasma is utilized to fabricate carbon nanotubes on the prepatterned Ni catalyst which in turn can confine the plasma to the growth region. The plasma localization leads to a dielectrophoretic force exerted on Ni atoms and can be engineered in order to grow a specific pattern of self-organized single-standing carbon nanotubes. Numerical simulations based on the plasma localization and dielectrophoretic force confirmed the experimental results. This method provides a simple and cost-effective approach to obtain nanopatterned arrays of carbon nanotubes which can be used for fabrication of photonic and phononic crystals, self-gated field emission-based transistors and displays.

  7. Surface-induced patterns from evaporating droplets of aqueous carbon nanotube dispersions

    KAUST Repository

    Zeng, Hongbo; Kristiansen, Kai De Lange; Wang, Peng; Bergli, Joakim; Israelachvili, Jacob N.

    2011-01-01

    Evaporation of aqueous droplets of carbon nanotubes (CNTs) coated with a physisorbed layer of humic acid (HA) on a partially hydrophilic substrate induces the formation of a film of CNTs. Here, we investigate the role that the global geometry of the substrate surfaces has on the structure of the CNT film. On a flat mica or silica surface, the evaporation of a convex droplet of the CNT dispersion induces the well-known "coffee ring", while evaporation of a concave droplet (capillary meniscus) of the CNT dispersion in a wedge of two planar mica sheets or between two crossed-cylinder sheets induces a large area (>mm 2) of textured or patterned films characterized by different short- and long-range orientational and positional ordering of the CNTs. The resulting patterns appear to be determined by two competing or cooperative sedimentation mechanisms: (1) capillary forces between CNTs giving micrometer-sized filaments parallel to the boundary line of the evaporating droplet and (2) fingering instability at the boundary line of the evaporating droplet and subsequent pinning of CNTs on the surface giving micrometer-sized filaments of CNTs perpendicular to this boundary line. The interplay between substrate surface geometry and sedimentation mechanisms gives an extra control parameter for manipulating patterns of self-assembling nanoparticles at substrate surfaces. © 2011 American Chemical Society.

  8. Surface-induced patterns from evaporating droplets of aqueous carbon nanotube dispersions

    KAUST Repository

    Zeng, Hongbo

    2011-06-07

    Evaporation of aqueous droplets of carbon nanotubes (CNTs) coated with a physisorbed layer of humic acid (HA) on a partially hydrophilic substrate induces the formation of a film of CNTs. Here, we investigate the role that the global geometry of the substrate surfaces has on the structure of the CNT film. On a flat mica or silica surface, the evaporation of a convex droplet of the CNT dispersion induces the well-known "coffee ring", while evaporation of a concave droplet (capillary meniscus) of the CNT dispersion in a wedge of two planar mica sheets or between two crossed-cylinder sheets induces a large area (>mm 2) of textured or patterned films characterized by different short- and long-range orientational and positional ordering of the CNTs. The resulting patterns appear to be determined by two competing or cooperative sedimentation mechanisms: (1) capillary forces between CNTs giving micrometer-sized filaments parallel to the boundary line of the evaporating droplet and (2) fingering instability at the boundary line of the evaporating droplet and subsequent pinning of CNTs on the surface giving micrometer-sized filaments of CNTs perpendicular to this boundary line. The interplay between substrate surface geometry and sedimentation mechanisms gives an extra control parameter for manipulating patterns of self-assembling nanoparticles at substrate surfaces. © 2011 American Chemical Society.

  9. Aloe vera Derived Activated High-Surface-Area Carbon for Flexible and High-Energy Supercapacitors.

    Science.gov (United States)

    Karnan, M; Subramani, K; Sudhan, N; Ilayaraja, N; Sathish, M

    2016-12-28

    Materials which possess high specific capacitance in device configuration with low cost are essential for viable application in supercapacitors. Herein, a flexible high-energy supercapacitor device was fabricated using porous activated high-surface-area carbon derived from aloe leaf (Aloe vera) as a precursor. The A. vera derived activated carbon showed mesoporous nature with high specific surface area of ∼1890 m 2 /g. A high specific capacitance of 410 and 306 F/g was achieved in three-electrode and symmetric two-electrode system configurations in aqueous electrolyte, respectively. The fabricated all-solid-state device showed a high specific capacitance of 244 F/g with an energy density of 8.6 Wh/kg. In an ionic liquid electrolyte, the fabricated device showed a high specific capacitance of 126 F/g and a wide potential window up to 3 V, which results in a high energy density of 40 Wh/kg. Furthermore, it was observed that the activation temperature has significant role in the electrochemical performance, as the activated sample at 700 °C showed best activity than the samples activated at 600 and 800 °C. The electron microscopic images (FE-SEM and HR-TEM) confirmed the formation of pores by the chemical activation. A fabricated supercapacitor device in ionic liquid with 3 V could power up a red LED for 30 min upon charging for 20s. Also, it is shown that the operation voltage and capacitance of flexible all-solid-state symmetric supercapacitors fabricated using aloe-derived activated carbon could be easily tuned by series and parallel combinations. The performance of fabricated supercapacitor devices using A. vera derived activated carbon in all-solid-state and ionic liquid indicates their viable applications in flexible devices and energy storage.

  10. Overview on the Surface Functionalization Mechanism and Determination of Surface Functional Groups of Plasma Treated Carbon Nanotubes.

    Science.gov (United States)

    Saka, Cafer

    2018-01-02

    The use of carbon materials for many applications is due to the unique diversity of structures and properties ranging from chemical bonds between the carbon atoms of the materials to nanostructures, crystallite alignment, and microstructures. Carbon nanotubes and other nanoscale carbonaceous materials draw much attention due to their physical and chemical properties, such as high strength, high resistance to corrosion, electrical and thermal conductivity, stability and a qualified adsorbent. Carbon-based nanomaterials, which have a relatively large specific area and layered structure, can be used as an adsorbent for efficient removal of organic and inorganic contaminants. However, one of the biggest obstacles to the development of carbon-based nanomaterials adsorbents is insolubility and the lack of functional groups on the surface. There are several approaches to introduce functional groups on carbon nanotubes. One of these approaches, plasma applications, now has an important place in the creation of surface functional groups as a flexible, fast, and environmentally friendly method. This review focuses on recent information concerning the surface functionalization and modification of plasma treated carbon nanotube. This review considers the surface properties, advantages, and disadvantages of plasma-applied carbon nanotubes. It also examines the reaction mechanisms involved in the functional groups on the surface.

  11. Interaction between Palladium Nanoparticles and Surface-Modified Carbon Nanotubes: Role of Surface Functionalities

    DEFF Research Database (Denmark)

    Zhang, Bingsen; Shao, Lidong; Zhang, Wei

    2014-01-01

    degrees C. We focus on probing the effects of oxygen and nitrogen-containing functional groups on supported palladium nanoparticles (NPs) in the model catalytic system. The stability of palladium NPs supported on CNTs depends strongly on the surface properties of CNTs. Moreover, the oxygen...... feature, instability, and subtle response of the components upon application of an external field. Herein, we use insitu TEM, electron energy loss spectroscopy, and X-ray photoelectron spectroscopy techniques to record the interaction in palladium on carbon nanotubes (CNTs) from room temperature to 600...

  12. Functionalized granular activated carbon and surface complexation with chromates and bi-chromates in wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Singha, Somdutta; Sarkar, Ujjaini, E-mail: usarkar@chemical.jdvu.ac.in; Luharuka, Pallavi

    2013-03-01

    Cr(VI) is present in the aqueous medium as chromate (CrO{sub 4}{sup 2−}) and bi-chromate (HCrO{sub 4}{sup −}). Functionalized granular activated carbons (FACs) are used as adsorbents in the treatment of wastewaters containing hexavalent chromium. The FACs are prepared by chemical modifications of granular activated carbons (GACs) using functionalizing agents like HNO{sub 3}, HCl and HF. The Brunauer, Emmett and Teller surface areas of FAC-HCl (693.5 m{sup 2}/g), FAC-HNO{sub 3} (648.8 m{sup 2}/g) and FAC-HF (726.2 m{sup 2}/g) are comparable to the GAC (777.7 m{sup 2}/g). But, the adsorption capacity of each of the FAC-HNO{sub 3}, FAC-HCl and FAC-HF is found to be higher than the GAC. The functional groups play an important role in the adsorption process and pH has practically no role in this specific case. The FACs have hydrophilic protonated external surfaces in particular, along with the functional surface sites capable to make complexes with the CrO{sub 4}{sup 2−} and HCrO{sub 4}{sup −} present. Surface complex formation is maximized in the order FAC-HNO{sub 3} > FAC-HF > FAC-HCl, in proportion to the total surface acidity. This is also confirmed by the well-known pseudo second-order kinetic model. Physi-sorption equilibrium isotherms are parameterized by using standard Freundlich and Langmuir models. Langmuir fits better. The formation of surface complexes with the functional groups and hexavalent chromium is also revealed in the images of field emission scanning electron micrograph; energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy analysis after adsorption. The intra-particle diffusion is not the only rate-controlling factor. The Boyd's film diffusion model fits very well with R{sup 2} as high as 98.1% for FAC-HNO{sub 3}. This result demonstrates that the functionalization of the GAC by acid treatments would increase the diffusion rate, predominantly with a boundary layer diffusion effect. - Highlights: ► Physico

  13. Formation of palladium(0) nanoparticles at microbial surfaces

    DEFF Research Database (Denmark)

    Bunge, Michael; Søbjerg, Lina S; Rotaru, Amelia-Elena

    2010-01-01

    ) nanoparticles were still deposited on autoclaved cells of C. necator that had no hydrogenase activity, suggesting a hydrogenase-independent formation mechanism. The catalytic properties of Pd(0) and bioPd(0) were determined by the amount of hydrogen released in a reaction with hypophosphite. Generally, bioPd(0...... potential. Hitherto, bacteria with the property of dissimilatory metal reduction have been in focus, although the biochemical reactions linking enzymatic Pd(II) reduction and Pd(0) deposition have not yet been identified. In this study we investigated Pd(II) reduction with formate as the electron donor......) demonstrated a lower level of activity than the Pd(0) control, possibly due to the inaccessibility of the Pd(0) fraction embedded in the cell envelope. Our results demonstrate the suitability of bacterial cells for the recovery of Pd(0), and formation and immobilization of Pd(0) nanoparticles inside the cell...

  14. Carbonic acid as a reserve of carbon dioxide on icy moons: The formation of carbon dioxide (CO2) in a polar environment

    International Nuclear Information System (INIS)

    Jones, Brant M.; Kaiser, Ralf I.; Strazzulla, Giovanni

    2014-01-01

    Carbon dioxide (CO 2 ) has been detected on the surface of several icy moons of Jupiter and Saturn via observation of the ν 3 band with the Near-Infrared Mapping Spectrometer on board the Galileo spacecraft and the Visible-Infrared Mapping Spectrometer on board the Cassini spacecraft. Interestingly, the CO 2 band for several of these moons exhibits a blueshift along with a broader profile than that seen in laboratory studies and other astrophysical environments. As such, numerous attempts have been made in order to clarify this abnormal behavior; however, it currently lacks an acceptable physical or chemical explanation. We present a rather surprising result pertaining to the synthesis of carbon dioxide in a polar environment. Here, carbonic acid was synthesized in a water (H 2 O)-carbon dioxide (CO 2 ) (1:5) ice mixture exposed to ionizing radiation in the form of 5 keV electrons. The irradiated ice mixture was then annealed, producing pure carbonic acid which was then subsequently irradiated, recycling water and carbon dioxide. However, the observed carbon dioxide ν 3 band matches almost exactly with that observed on Callisto; subsequent temperature program desorption studies reveal that carbon dioxide synthesized under these conditions remains in solid form until 160 K, i.e., the sublimation temperature of water. Consequently, our results suggest that carbon dioxide on Callisto as well as other icy moons is indeed complexed with water rationalizing the shift in peak frequency, broad profile, and the solid state existence on these relatively warm moons.

  15. Mixed resin and carbon fibres surface treatment for preparation of carbon fibres composites with good interfacial bonding strength

    International Nuclear Information System (INIS)

    He, Hongwei; Wang, Jianlong; Li, Kaixi; Wang, Jian; Gu, Jianyu

    2010-01-01

    The objective of this work is to improve the interlaminar shear strength of composites by mixing epoxy resin and modifying carbon fibres. The effect of mixed resin matrix's structure on carbon fibres composites was studied. Anodic oxidation treatment was used to modify the surface of carbon fibres. The tensile strength of multifilament and interlaminar shear strength of composites were investigated respectively. The morphologies of untreated and treated carbon fibres were characterized by scanning electron microscope and X-ray photoelectron spectroscopy. Surface analysis indicates that the amount of carbon fibres chemisorbed oxygen-containing groups, active carbon atom, the surface roughness, and wetting ability increases after treatment. The tensile strength of carbon fibres decreased little after treatment by anodic oxidation. The results show that the treated carbon fibres composites could possess excellent interfacial properties with mixed resins, and interlaminar shear strength of the composites is up to 85.41 MPa. The mechanism of mixed resins and treated carbon fibres to improve the interfacial property of composites is obtained.

  16. Laser gas assisted texturing and formation of nitride and oxynitride compounds on alumina surface: Surface response to environmental dust

    Science.gov (United States)

    Yilbas, B. S.; Ali, H.; Al-Sharafi, A.; Al-Aqeeli, N.

    2018-03-01

    Laser gas assisted texturing of alumina surface is carried out, and formation of nitride and oxynitride compounds in the surface vicinity is examined. The laser parameters are selected to create the surface topology consisting of micro/nano pillars with minimum defect sites including micro-cracks, voids and large size cavities. Morphological and hydrophobic characteristics of the textured surface are examined using the analytical tools. The characteristics of the environmental dust and its influence on the laser textured surface are studied while mimicking the local humid air ambient. Adhesion of the dry mud on the laser textured surface is assessed through the measurement of the tangential force, which is required to remove the dry mud from the surface. It is found that laser texturing gives rise to micro/nano pillars topology and the formation of AlN and AlON compounds in the surface vicinity. This, in turn, lowers the free energy of the textured surface and enhances the hydrophobicity of the surface. The liquid solution resulted from the dissolution of alkaline and alkaline earth metals of the dust particles in water condensate forms locally scattered liquid islands at the interface of mud and textured surface. The dried liquid solution at the interface increases the dry mud adhesion on the textured surface. Some dry mud residues remain on the textured surface after the dry mud is removed by a pressurized desalinated water jet.

  17. Study of the surface chemistry and morphology of single walled carbon nanotube-magnetite composites

    International Nuclear Information System (INIS)

    Marquez-Linares, F.; Uwakweh, O.N.C.; Lopez, N.; Chavez, E.; Polanco, R.; Morant, C.; Sanz, J.M.; Elizalde, E.; Neira, C.; Nieto, S.; Roque-Malherbe, R.

    2011-01-01

    The study of the morphologies of the single walled carbon nanotube (SWCNT), magnetite nanoparticles (MNP), and the composite based on them was carried with combined X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). These techniques together with thermogravimetric analyses (TGA) and diffuse reflectance infrared transform spectroscopy (DRIFTS) confirmed the production of pure single phases, and that the composite material consisted of MNP attached to the outer surface of the SWCNT. The Moessbauer spectroscopy (MS) research showed the presence of a large quantity of Lewis acid sites in the highly dispersed magnetite particles supported on the SWCNT outer surface. The DRIFTS carbon dioxide adsorption study of the composites revealed significant adsorption of carbon dioxide, fundamentally in the Lewis acid sites. Then, the Lewis acid sites were observed to be catalytically active. Further, the electron exchange between the Lewis acid sites and the basic or amphoteric adsorbed molecules could influence the magnetic properties of the magnetite. Consequently, together with this first ever use of MS in the study of Lewis acid sites, this investigation revealed the potential of the composites for catalytic and sensors applications. -- Graphical abstract: A large amount of Lewis acid sites were found in the highly dispersed magnetite which is supported on the SWCNT outer surface. Display Omitted Research highlights: → The obtained materials were completely characterized with XRD, Raman and SEM-TEM. → DRIFT, TGA and adsorption of the composites allowed understand the material formation. → This is the first report of a study of Lewis sites by Moessbauer spectroscopy.

  18. Formation and development of salt crusts on soil surfaces

    KAUST Repository

    Dai, Sheng; Shin, Hosung; Santamarina, Carlos

    2015-01-01

    The salt concentration gradually increases at the soil free surface when the evaporation rate exceeds the diffusive counter transport. Eventually, salt precipitates and crystals form a porous sodium chloride crust with a porosity of 0.43 ± 0.14. After detaching from soils, the salt crust still experiences water condensation and salt deliquescence at the bottom, brine transport across the crust driven by the humidity gradient, and continued air-side precipitation. This transport mechanism allows salt crust migration away from the soil surface at a rate of 5 μm/h forming salt domes above soil surfaces. The surface characteristics of mineral substrates and the evaporation rate affect the morphology and the crystal size of precipitated salt. In particular, substrate hydrophobicity and low evaporation rate suppress salt spreading.

  19. Formation and development of salt crusts on soil surfaces

    KAUST Repository

    Dai, Sheng

    2015-12-14

    The salt concentration gradually increases at the soil free surface when the evaporation rate exceeds the diffusive counter transport. Eventually, salt precipitates and crystals form a porous sodium chloride crust with a porosity of 0.43 ± 0.14. After detaching from soils, the salt crust still experiences water condensation and salt deliquescence at the bottom, brine transport across the crust driven by the humidity gradient, and continued air-side precipitation. This transport mechanism allows salt crust migration away from the soil surface at a rate of 5 μm/h forming salt domes above soil surfaces. The surface characteristics of mineral substrates and the evaporation rate affect the morphology and the crystal size of precipitated salt. In particular, substrate hydrophobicity and low evaporation rate suppress salt spreading.

  20. Biofilm formation on a TiO2 nanotube with controlled pore diameter and surface wettability

    International Nuclear Information System (INIS)

    Anitha, V C; Narayan Banerjee, Arghya; Woo Joo, Sang; Lee, Jin-Hyung; Lee, Jintae; Ki Min, Bong

    2015-01-01

    Titania (TiO 2 ) nanotube arrays (TNAs) with different pore diameters (140 − 20 nm) are fabricated via anodization using hydrofluoric acid (HF) containing ethylene glycol (EG) by changing the HF-to-EG volume ratio and the anodization voltage. To evaluate the effects of different pore diameters of TiO 2 nanotubes on bacterial biofilm formation, Shewanella oneidensis (S. oneidensis) MR-1 cells and a crystal-violet biofilm assay are used. The surface roughness and wettability of the TNA surfaces as a function of pore diameter, measured via the contact angle and AFM techniques, are correlated with the controlled biofilm formation. Biofilm formation increases with the decreasing nanotube pore diameter, and a 20 nm TiO 2 nanotube shows the maximum biofilm formation. The measurements revealed that 20 nm surfaces have the least hydrophilicity with the highest surface roughness of ∼17 nm and that they show almost a 90% increase in the effective surface area relative to the 140 nm TNAs, which stimulate the cells more effectively to produce the pili to attach to the surface for more biofilm formation. The results demonstrate that bacterial cell adhesion (and hence, biofilm formation) can effectively be controlled by tuning the roughness and wettability of TNAs via controlling the pore diameters of TNA surfaces. This biofilm formation as a function of the surface properties of TNAs can be a potential candidate for both medical applications and as electrodes in microbial fuel cells. (paper)

  1. Electrical conductivity of conductive carbon blacks: influence of surface chemistry and topology

    International Nuclear Information System (INIS)

    Pantea, Dana; Darmstadt, Hans; Kaliaguine, Serge; Roy, Christian

    2003-01-01

    Conductive carbon blacks from different manufacturers were studied in order to obtain some insight into the relation between their electrical conductivity and their surface properties. The surface chemistry was studied by X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectroscopy (SIMS), whereas the topology of the carbon black surface was investigated using low-pressure nitrogen adsorption. All these techniques yield information on the graphitic character of the surface. In general, the electrical conductivity of the conductive blacks increases with the graphitic character of the surface. For low surface area conductive blacks, the electrical conductivity correlates well with the surface chemistry. In the case of the XPS and SIMS data, this correlation is also valid when other types of carbon blacks such as thermal and furnace blacks are included, confirming the determining influence of the carbon black surface chemistry on the electrical conductivity

  2. Construction of Polarized Carbon-Nickel Catalytic Surfaces for Potent, Durable, and Economic Hydrogen Evolution Reactions.

    Science.gov (United States)

    Zhou, Min; Weng, Qunhong; Popov, Zakhar I; Yang, Yijun; Antipina, Liubov Yu; Sorokin, Pavel B; Wang, Xi; Bando, Yoshio; Golberg, Dmitri

    2018-05-22

    Electrocatalytic hydrogen evolution reaction (HER) in alkaline solution is hindered by its sluggish kinetics toward water dissociation. Nickel-based catalysts, as low-cost and effective candidates, show great potentials to replace platinum (Pt)-based materials in the alkaline media. The main challenge regarding this type of catalysts is their relatively poor durability. In this work, we conceive and construct a charge-polarized carbon layer derived from carbon quantum dots (CQDs) on Ni 3 N nanostructure (Ni 3 N@CQDs) surfaces, which simultaneously exhibit durable and enhanced catalytic activity. The Ni 3 N@CQDs shows an overpotential of 69 mV at a current density of 10 mA cm -2 in a 1 M KOH aqueous solution, lower than that of Pt electrode (116 mV) at the same conditions. Density functional theory (DFT) simulations reveal that Ni 3 N and interfacial oxygen polarize charge distributions between originally equal C-C bonds in CQDs. The partially negatively charged C sites become effective catalytic centers for the key water dissociation step via the formation of new C-H bond (Volmer step) and thus boost the HER activity. Furthermore, the coated carbon is also found to protect interior Ni 3 N from oxidization/hydroxylation and therefore guarantees its durability. This work provides a practical design of robust and durable HER electrocatalysts based on nonprecious metals.

  3. Effect of surface modification on carbon fiber and its reinforced phenolic matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Hua [Key Laboratory for Liquid phase chemical oxidation Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan 250061 (China); Carbon Fibre Engineering Research Center, Faculty of Materials Science, Shandong University, Jinan 250061 (China); Wang Chengguo, E-mail: sduwangchg@gmail.com [Carbon Fibre Engineering Research Center, Faculty of Materials Science, Shandong University, Jinan 250061 (China); Zhang Shan; Lin Xue [Carbon Fibre Engineering Research Center, Faculty of Materials Science, Shandong University, Jinan 250061 (China)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer We used very simple and effective modification method to treat PAN-based carbon fiber by liquid oxidation and coupling agent. Black-Right-Pointing-Pointer Carbon fiber surface functional groups were analyzed by LRS and XPS. Black-Right-Pointing-Pointer Proper treatment of carbon fiber can prove an effective way to increase composite's performance. Black-Right-Pointing-Pointer Carbon fiber surface modifications by oxidation and APS could strengthen fiber activity and enlarge surface area as well as its roughness. - Abstract: In this work, polyacrylonitrile (PAN)-based carbon fiber were chemically modified with H{sub 2}SO{sub 4}, KClO{sub 3} and silane coupling agent ({gamma}-aminopropyltriethoxysilane, APS), and carbon fiber reinforced phenolic matrix composites were prepared. The structural and surface characteristics of the carbon fiber were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), laser Raman scattering (LRS) and Fourier transform infrared spectroscopy (FTIR). Single fiber mechanical properties, specific surface area, composite impact properties and interfacial shear strength (ILSS) were researched to indicate the effects of surface modification on fibers and the interaction between modified fiber surface and phenolic matrix. The results showed that carbon fiber surface modification by oxidation and APS can strengthen fiber surface chemical activity and enlarge the fiber surface area as well as its roughness. When carbon fiber (CF) is oxidized treatment, the oxygen content as well as the O/C ratio will be obviously increased. Oxygen functional groups increase with oxidation time increasing. Carbon fiber treated with APS will make C-O-R content increase and O-C=O content decrease due to surface reaction. Proper treatment of carbon fiber with acid and silane coupling agent prove an effective way to increase the interfacial adhesion and improve the mechanical and outdoor

  4. Effect of surface modification on carbon fiber and its reinforced phenolic matrix composite

    International Nuclear Information System (INIS)

    Yuan Hua; Wang Chengguo; Zhang Shan; Lin Xue

    2012-01-01

    Highlights: ► We used very simple and effective modification method to treat PAN-based carbon fiber by liquid oxidation and coupling agent. ► Carbon fiber surface functional groups were analyzed by LRS and XPS. ► Proper treatment of carbon fiber can prove an effective way to increase composite's performance. ► Carbon fiber surface modifications by oxidation and APS could strengthen fiber activity and enlarge surface area as well as its roughness. - Abstract: In this work, polyacrylonitrile (PAN)-based carbon fiber were chemically modified with H 2 SO 4 , KClO 3 and silane coupling agent (γ-aminopropyltriethoxysilane, APS), and carbon fiber reinforced phenolic matrix composites were prepared. The structural and surface characteristics of the carbon fiber were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), laser Raman scattering (LRS) and Fourier transform infrared spectroscopy (FTIR). Single fiber mechanical properties, specific surface area, composite impact properties and interfacial shear strength (ILSS) were researched to indicate the effects of surface modification on fibers and the interaction between modified fiber surface and phenolic matrix. The results showed that carbon fiber surface modification by oxidation and APS can strengthen fiber surface chemical activity and enlarge the fiber surface area as well as its roughness. When carbon fiber (CF) is oxidized treatment, the oxygen content as well as the O/C ratio will be obviously increased. Oxygen functional groups increase with oxidation time increasing. Carbon fiber treated with APS will make C-O-R content increase and O-C=O content decrease due to surface reaction. Proper treatment of carbon fiber with acid and silane coupling agent prove an effective way to increase the interfacial adhesion and improve the mechanical and outdoor performance of the resulting fiber/resin composites.

  5. Surface modification of pyrolyzed carbon fibres by cyclic voltammetry and their characterization with XPS and dye adsorption

    International Nuclear Information System (INIS)

    Georgiou, P.; Walton, J.; Simitzis, J.

    2010-01-01

    Commercial carbon fibres were pyrolyzed up to 1000 deg. C and were then electrochemically treated by cyclic voltammetry in aqueous electrolyte solutions of H 2 SO 4 , in two potential sweep ranges: a narrow region, N, and a wide region, W, avoiding and including water decomposition, respectively. The anodic and cathodic peaks were correlated with oxide formation and their partial reduction, respectively. The nature of oxygen containing groups on the fibre surfaces was determined by XPS. Wide scan spectra and high energy resolution spectra were recorded through the C 1s, O 1s, N 1s and S 2p photoelectron regions. The ability of the fibres to adsorb methylene blue and alizarin yellow dyes from their aqueous solutions indicates the presence of electron acceptor or donor groups on the fibres, respectively. The carbon fibres were classified into two categories. The first includes electrochemically untreated and treated in the N region, and the second those treated in the W region. The high oxygen concentration and effective dye adsorption on the carbon fibres in the second category indicates that their surfaces were effectively modified. The adsorption of dyes on carbon fibres constitutes a complementary method to XPS for an indirect estimation of oxygen and other groups present on the carbon fibre surfaces.

  6. Surface modification of platelet concentrate bags to reduce biofilm formation and transfusion sepsis.

    Science.gov (United States)

    Wilson-Nieuwenhuis, Joels S T; Dempsey-Hibbert, Nina; Liauw, Christopher M; Whitehead, Kathryn A

    2017-12-01

    Bacterial contamination of blood products poses a major risk in transfusion medicine, including transfusions involving platelet products. Although testing systems are in place for routine screening of platelet units, the formation of bacterial biofilms in such units may decrease the likelihood that bacteria will be detected. This work determined the surface properties of p-PVC platelet concentrate bags and investigated how these characteristics influenced biofilm formation. Serratia marcescens and Staphylococcus epidermidis, two species commonly implicated in platelet contamination, were used to study biofilm growth. The platelet concentrate bags were physically flattened to determine if reducing the surface roughness altered biofilm formation. The results demonstrated that the flattening process of the platelet bags affected the chemistry of the surface and reduced the surface hydrophobicity. Flattening of the surfaces resulted in a reduction in biofilm formation for both species after 5 days, with S. marcescens demonstrating a greater reduction. However, there was no significant difference between the smooth and flat surfaces following 7 days' incubation for S. marcescens and no significant differences between any of the surfaces following 7 days' incubation for S. epidermidis. The results suggest that flattening the p-PVC surfaces may limit potential biofilm formation for the current duration of platelet storage time of 5 days. It is hoped that this work will enhance the understanding of how surface properties influence the development of microbial biofilms in platelet concentrate bags in order to devise a solution to discourage biofilm formation. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Carbon on Mercury's Surface — Origin, Distribution, and Concentration

    Science.gov (United States)

    Klima, R. L.; Blewett, D. T.; Denevi, B. W.; Ernst, C. M.; Murchie, S. L.; Peplowski, P. N.; Perera, V.; Vander Kaaden, K.

    2018-05-01

    Low-reflectance material on Mercury, excavated from depth, may contain up to 5wt% carbon in some areas of the planet. We interpret this as endogenic carbon associated with the earliest crust of Mercury.

  8. Characterization of EUV induced carbon films using laser-generated surface acoustic waves

    NARCIS (Netherlands)

    Chen, Juequan; Lee, Christopher James; Louis, Eric; Bijkerk, Frederik; Kunze, Reinhard; Schmidt, Hagen; Schneider, Dieter; Moors, Roel

    2009-01-01

    The deposition of carbon layers on the surfaces of optics exposed to extreme ultraviolet (EUV) radiation has been observed in EUV lithography. It has become of critical importance to detect the presence of the carbon layer in the order of nanometer thickness due to carbon's extremely strong

  9. Bainite Formation in Medium-Carbon Low-Silicon Spring Steels Accounting for Chemical Segregation

    NARCIS (Netherlands)

    Goulas, C.; Mecozzi, M.G.; Sietsma, J.

    2016-01-01

    In this paper, the effect of chemical inhomogeneity on the isothermal bainite formation is investigated in medium-carbon low-silicon spring steel by dilatometry and microscopy. The analysis of the microstructure at different times during transformation shows that chemical segregation of

  10. Hydrogenation of silyl formates: sustainable production of silanol and methanol from hydrosilane and carbon dioxide.

    Science.gov (United States)

    Koo, Jangwoo; Kim, Seung Hyo; Hong, Soon Hyeok

    2018-05-10

    A new process for simultaneously obtaining two chemical building blocks, methanol and silanol, was realized starting from silyl formates which can be derived from silane and carbon dioxide. Understanding the reaction mechanism enabled us to improve the reaction efficiency by the addition of a small amount of methanol.

  11. Study on Surface Integrity of AISI 1045 Carbon Steel when machined by Carbide Cutting Tool under wet conditions

    Directory of Open Access Journals (Sweden)

    Tamin N. Fauzi

    2017-01-01

    Full Text Available This paper presents the evaluation of surface roughness and roughness profiles when machining carbon steel under wet conditions with low and high cutting speeds. The workpiece materials and cutting tools selected in this research were AISI 1045 carbon steel and canela carbide inserts graded PM25, respectively. The cutting tools undergo machining tests by CNC turning operations and their performances were evaluated by their surface roughness value and observation of the surface roughness profile. The machining tests were held at varied cutting speeds of 35 to 53 m/min, feed rate of 0.15 to 0.50 mm/rev and a constant depth of cut of 1 mm. From the analysis, it was found that surface roughness increased as the feed rate increased. Varian of surface roughness was suspected due to interaction between cutting speeds and feed rates as well as nose radius conditions; whether from tool wear or the formation of a built-up edge. This study helps us understand the effect of cutting speed and feed rate on surface integrity, when machining AISI 1045 carbon steel using carbide cutting tools, under wet cutting conditions.

  12. Electron density as the main parameter influencing the formation of fullerenes in a carbon plasma

    International Nuclear Information System (INIS)

    Churilov, G.N.; Bulina, N.V.; Novikov, P.V.; Lopatin, V.A.; Vnukova, N.G.; Bachilo, S.M.; Tsyboulski, D.; Weisman, R.B.

    2002-01-01

    Thermodynamic estimates are presented for the formation of spheroidal and flat carbon clusters from reactant species of different charges. Charge is shown to strongly influence the geometry and stability of flat clusters. Changes in the charge of flat clusters can promote both their folding to spheroidal structures and their dissociation. It is concluded that the fluctuations of electron concentration in carbon plasma can result in the accumulation of fullerene clusters and the dissociation of flat clusters. Computer simulations of fullerene C 60 formation from carbon clusters having different charges are carried out using the program HyperChem 5 to calculate the optimal geometry of molecules and their molecular dynamics at different temperatures [ru

  13. Proteins involved in flor yeast carbon metabolism under biofilm formation conditions.

    Science.gov (United States)

    Moreno-García, Jaime; García-Martínez, Teresa; Moreno, Juan; Mauricio, Juan Carlos

    2015-04-01

    A lack of sugars during the production of biologically aged wines after fermentation of grape must causes flor yeasts to metabolize other carbon molecules formed during fermentation (ethanol and glycerol, mainly). In this work, a proteome analysis involving OFFGEL fractionation prior to LC/MS detection was used to elucidate the carbon metabolism of a flor yeast strain under biofilm formation conditions (BFC). The results were compared with those obtained under non-biofilm formation conditions (NBFC). Proteins associated to processes such as non-fermentable carbon uptake, the glyoxylate and TCA cycles, cellular respiration and inositol metabolism were detected at higher concentrations under BFC than under the reference conditions (NBFC). This study constitutes the first attempt at identifying the flor yeast proteins responsible for the peculiar sensory profile of biologically aged wines. A better metabolic knowledge of flor yeasts might facilitate the development of effective strategies for improved production of these special wines. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Carbonate deposition, Pyramid Lake subbasin, Nevada: 1. Sequence of formation and elevational distribution of carbonate deposits (Tufas)

    Science.gov (United States)

    Benson, L.

    1994-01-01

    During the late Quarternary, the elevation of terrace cutting and carbonate deposition in the Pyramid Lake subbasin were controlled by constancy of lake level imposed by spill to adjoining subbasins. Sill elevations are 1177-1183 m (Mud Lake Slough Sill), 1207 m (Emerson Pass Sill), and 1265 m (Darwin Pass Sill). Carbonate deposition was favored by: (1) hydrologic closure, (2) proximity to a source of calcium, (3) elevated water temperature, and (4) a solid substrate. The thickness and aspect of tufa are a function oflake-level dynamics. Relatively thin sheets and pendant sheets were deposited during a rising or falling lake. The upper parts of thick reef-form tufas have a horizontal aspect and were deposited in a lake which was stabilized by spill to the Carson Desert subbasin. The lower parts of the reef-form tufas are thinner and their outer surface has a vertical aspect, indicating that the lower part formed in a receding lake. The thickest and most complete sequences of tufa are mounds that border the Pyramid Lake shore. The tops of the tallest mounds reach the elevation of the Darwin Pass Sill and many mounds have been eroded to the elevations of the Mud Lake Slough Sill of the Emerson Pass Sill. The sequence of tufa formation (from oldest to youngest) displayed in these mounds is: (1) a beachrock containing carbonate-cemented volcanic cobbles, (2) broken and eroded old spheroids that contain thinolitic tufa and an outer rind of dense laminated tufa, (3) large cylindrical (tubular) tufas capped by (4) coatings of old dense tufas, and (5) several generations of old branching tufa commonly associated with thin, platy tufas and coatings of thinolitic tufa, (6) young spheroids that contain poorly oriented young thinolitic tufa in the center and several generations of radially oriented young thinolitic tufas near the outer edge, (7) a transitional thinolite-to-branching tufa, (8) two or more layers of young branching tufa, (9) a 0.5-cm-thick layer of fine

  15. Effect of high surface area activated carbon on thermal degradation of jet fuel

    Energy Technology Data Exchange (ETDEWEB)

    Gergova, K.; Eser, S.; Arumugam, R.; Schobert, H.H. [Pennsylvania State Univ., University Park, PA (United States)

    1995-05-01

    Different solid carbons added to jet fuel during thermal stressing cause substantial changes in pyrolytic degradation reactions. Activated carbons, especially high surface area activated carbons were found to be very effective in suppressing solid deposition on metal reactor walls during stressing at high temperatures (425 and 450{degrees}C). The high surface area activated carbon PX-21 prevented solid deposition on reactor walls even after 5h at 450{degrees}C. The differences seen in the liquid product composition when activated carbon is added indicated that the carbon surfaces affect the degradation reactions. Thermal stressing experiments were carried out on commercial petroleum-derived JPTS jet fuel. We also used n-octane and n-dodecane as model compounds in order to simplify the study of the chemical changes which take place upon activated carbon addition. In separate experiments, the presence of a hydrogen donor, decalin, together with PX-21 was also studied.

  16. Effects of black carbon and boundary layer interaction on surface ozone in Nanjing, China

    Science.gov (United States)

    Gao, Jinhui; Zhu, Bin; Xiao, Hui; Kang, Hanqing; Pan, Chen; Wang, Dongdong; Wang, Honglei

    2018-05-01

    As an important solar radiation absorbing aerosol, the effect of black carbon (BC) on surface ozone, via reducing photolysis rate, has been widely discussed by offline model studies. However, BC-boundary layer (BL) interactions also influence surface ozone. Using the online model simulations and process analysis, we demonstrate the significant impact of BC-BL interaction on surface ozone in Nanjing. The absorbing effect of BC heats the air above the BL and suppresses and delays the development of the BL, which eventually leads to a change in surface ozone via a change in the contributions from chemical and physical processes (photochemistry, vertical mixing and advection). For chemical processes, the suppression of the BL leads to large amounts of ozone precursors being confined below the BL which has an increased effect on ozone chemical production and offsets the decrease caused by the reduction of the photolysis rate, thus enhancing ozone chemical formation from 10:00 to 12:00 LT. Furthermore, changes in physical processes, especially the vertical mixing process, show a more significant influence on surface ozone. The weakened turbulence, caused by the suppressed BL, entrains much less ozone aloft down to the surface. Finally, summing-up the changes in the processes, surface ozone reduces before noon and the maximum reduction reaches 16.4 ppb at 12:00 LT. In the afternoon, the changes in chemical process are small which inconspicuously influence surface ozone. However, change in the vertical mixing process still influences surface ozone significantly. Due to the delayed development of the BL, there are obvious ozone gradients around the top of BL. Therefore, high concentrations of ozone aloft can still be entrained down to the surface which offsets the reduction of surface ozone. Comparing the changes in the processes, the change in vertical mixing plays the most important role in impacting surface ozone. Our results highlight the great impacts BC

  17. Effects of black carbon and boundary layer interaction on surface ozone in Nanjing, China

    Directory of Open Access Journals (Sweden)

    J. Gao

    2018-05-01

    Full Text Available As an important solar radiation absorbing aerosol, the effect of black carbon (BC on surface ozone, via reducing photolysis rate, has been widely discussed by offline model studies. However, BC–boundary layer (BL interactions also influence surface ozone. Using the online model simulations and process analysis, we demonstrate the significant impact of BC–BL interaction on surface ozone in Nanjing. The absorbing effect of BC heats the air above the BL and suppresses and delays the development of the BL, which eventually leads to a change in surface ozone via a change in the contributions from chemical and physical processes (photochemistry, vertical mixing and advection. For chemical processes, the suppression of the BL leads to large amounts of ozone precursors being confined below the BL which has an increased effect on ozone chemical production and offsets the decrease caused by the reduction of the photolysis rate, thus enhancing ozone chemical formation from 10:00 to 12:00 LT. Furthermore, changes in physical processes, especially the vertical mixing process, show a more significant influence on surface ozone. The weakened turbulence, caused by the suppressed BL, entrains much less ozone aloft down to the surface. Finally, summing-up the changes in the processes, surface ozone reduces before noon and the maximum reduction reaches 16.4 ppb at 12:00 LT. In the afternoon, the changes in chemical process are small which inconspicuously influence surface ozone. However, change in the vertical mixing process still influences surface ozone significantly. Due to the delayed development of the BL, there are obvious ozone gradients around the top of BL. Therefore, high concentrations of ozone aloft can still be entrained down to the surface which offsets the reduction of surface ozone. Comparing the changes in the processes, the change in vertical mixing plays the most important role in impacting surface ozone. Our results highlight the

  18. The Carbon Dioxide System in the Baltic Sea Surface Waters

    Energy Technology Data Exchange (ETDEWEB)

    Wesslander, Karin

    2011-05-15

    The concentration of carbon dioxide (CO{sub 2}) in the atmosphere is steadily increasing because of human activities such as fossil fuel burning. To understand how this is affecting the planet, several pieces of knowledge of the CO{sub 2} system have to be investigated. One piece is how the coastal seas, which are used by people and influenced by industrialization, are functioning. In this thesis, the CO{sub 2} system in the Baltic Sea surface water has been investigated using observations from the last century to the present. The Baltic Sea is characterized of a restricted water exchange with the open ocean and a large inflow of river water. The CO{sub 2} system, including parameters such as pH and partial pressure of CO{sub 2} (pCO{sub 2}), has large seasonal and inter-annual variability in the Baltic Sea. These parameters are affected by several processes, such as air-sea gas exchange, physical mixing, and biological processes. Inorganic carbon is assimilated in the primary production and pCO{sub 2} declines to approx150 muatm in summer. In winter, pCO{sub 2} levels increase because of prevailing mineralization and mixing processes. The wind-mixed surface layer deepens to the halocline (approx60 m) and brings CO{sub 2}- enriched water to the surface. Winter pCO{sub 2} may be as high as 600 muatm in the surface water. The CO{sub 2} system is also exposed to short-term variations caused by the daily biological cycle and physical events such as upwelling. A cruise was made in the central Baltic Sea to make synoptic measurements of oceanographic, chemical, and meteorological parameters with high temporal resolution. Large short-term variations were found in pCO{sub 2} and oxygen (O{sub 2}), which were highly correlated. The diurnal variation of pCO{sub 2} was up to 40 muatm. The CO{sub 2} system in the Baltic Sea changed as the industrialization increased around 1950, which was demonstrated using a coupled physical-biogeochemical model of the CO{sub 2} system

  19. Surface chloride salt formation on Space Shuttle exhaust alumina

    Science.gov (United States)

    Cofer, W. R., III; Pellett, G. L.; Sebacher, D. I.; Wakelyn, N. T.

    1984-01-01

    Aluminum oxide samples from the exhaust of Space Shuttle launches STS-1, STS-4, STS-5, and STS-6 were collected from surfaces on or around the launch pad complex and chemically analyzed. The results indicate that the particulate solid-propellant rocket motor (SRM) alumina was heavily chlorided. Concentrations of water-soluble aluminum (III) ion were large, suggesting that the surface of the SRM alumina particles was rendered soluble by prior reactions with HCl and H2O in the SRM exhaust cloud. These results suggest that Space Shuttle exhaust alumina particles are good sites for nucleation and condensation of atmospheric water. Laboratory experiments conducted at 220 C suggest that partial surface chloriding of alumina may occur in hot Space Shuttle exhaust plumes.

  20. Covalent-Bond Formation via On-Surface Chemistry.

    Science.gov (United States)

    Held, Philipp Alexander; Fuchs, Harald; Studer, Armido

    2017-05-02

    In this Review article pioneering work and recent achievements in the emerging research area of on-surface chemistry is discussed. On-surface chemistry, sometimes also called two-dimensional chemistry, shows great potential for bottom-up preparation of defined nanostructures. In contrast to traditional organic synthesis, where reactions are generally conducted in well-defined reaction flasks in solution, on-surface chemistry is performed in the cavity of a scanning probe microscope on a metal crystal under ultrahigh vacuum conditions. The metal first acts as a platform for self-assembly of the organic building blocks and in many cases it also acts as a catalyst for the given chemical transformation. Products and hence success of the reaction are directly analyzed by scanning probe microscopy. This Review provides a general overview of this chemistry highlighting advantages and disadvantages as compared to traditional reaction setups. The second part of the Review then focuses on reactions that have been successfully conducted as on-surface processes. On-surface Ullmann and Glaser couplings are addressed. In addition, cyclodehydrogenation reactions and cycloadditions are discussed and reactions involving the carbonyl functionality are highlighted. Finally, the first examples of sequential on-surface chemistry are considered in which two different functionalities are chemoselectively addressed. The Review gives an overview for experts working in the area but also offers a starting point to non-experts to enter into this exciting new interdisciplinary research field. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Study on the influence of carbon monoxide to the surface oxide layer of uranium metal

    International Nuclear Information System (INIS)

    Wang Xiaolin; Duan Rongliang; Fu Yibei; Xie Renshou; Zuo Changming; Zhao Chunpei; Chen Hong

    1997-01-01

    The influence of carbon monoxide to the surface oxide layer of uranium metal has been studied by X-ray photoelectron spectroscopy (XPS) and gas chromatography (GC). Carbon monoxide adsorption on the oxide layer resulted in U4f peak shifting to the lower binding energy. The content of oxygen in the oxide is decreased and the atomic ratio (O/U) is decreased by 7.2%. The amount of carbon dioxide in the atmosphere after the surface reaction is increased by 11.0%. The investigation indicates that the surface layer can prevent the further oxidation uranium metal in the atmosphere of carbon monoxide

  2. Fabrication of periodical surface structures by picosecond laser irradiation of carbon thin films: transformation of amorphous carbon in nanographite

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, C.; Dorcioman, G. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, Magurele RO-077125 (Romania); Bita, B. [National Institute for Research and Development in Microtechnologies, 126A Erou Iancu Nicolae Street, Voluntari RO-077190 (Romania); Faculty of Physics, 405 Atomistilor Street, Magurele RO-077125 (Romania); Besleaga, C.; Zgura, I. [National Institute of Materials Physics, 105bis Atomistilor Street, Magurele RO-077125 (Romania); Himcinschi, C. [Institute of Theoretical Physics, TU Bergakademie Freiberg, Freiberg D-09596 (Germany); Popescu, A.C., E-mail: andrei.popescu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, Magurele RO-077125 (Romania)

    2016-12-30

    Highlights: • Ripples obtained on carbon films after irradiation with visible ps laser pulses. • Amorphous carbon was transformed in nanographite following irradiation. • Ripples had a complex morphology, being made of islands of smaller ripples. • Hydrophilic carbon films became hydrophobic after surface structuring. - Abstract: Thin films of carbon were synthesized by ns pulsed laser deposition in vacuum on silicon substrates, starting from graphite targets. Further on, the films were irradiated with a picosecond laser source emitting in visible at 532 nm. After tuning of laser parameters, we obtained a film surface covered by laser induced periodical surface structures (LIPSS). They were investigated by optical, scanning electron and atomic force microscopy. It was observed that changing the irradiation angle influences the LIPSS covered area. At high magnification it was revealed that the LIPSS pattern was quite complex, being composed of other small LIPSS islands, interconnected by bridges of nanoparticles. Raman spectra for the non-irradiated carbon films were typical for a-C type of diamond-like carbon, while the LIPSS spectra were characteristic to nano-graphite. The pristine carbon film was hydrophilic, while the LIPSS covered film surface was hydrophobic.

  3. Adsorption of perfluoroalkyl acids by carbonaceous adsorbents: Effect of carbon surface chemistry

    International Nuclear Information System (INIS)

    Zhi, Yue; Liu, Jinxia

    2015-01-01

    Adsorption by carbonaceous sorbents is among the most feasible processes to remove perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) from drinking and ground waters. However, carbon surface chemistry, which has long been recognized essential for dictating performance of such sorbents, has never been considered for PFOS and PFOA adsorption. Thus, the role of surface chemistry was systematically investigated using sorbents with a wide range in precursor material, pore structure, and surface chemistry. Sorbent surface chemistry overwhelmed physical properties in controlling the extent of uptake. The adsorption affinity was positively correlated carbon surface basicity, suggesting that high acid neutralizing or anion exchange capacity was critical for substantial uptake of PFOS and PFOA. Carbon polarity or hydrophobicity had insignificant impact on the extent of adsorption. Synthetic polymer-based Ambersorb and activated carbon fibers were more effective than activated carbon made of natural materials in removing PFOS and PFOA from aqueous solutions. - Highlights: • Adsorption of PFOS and PFOA by ten carbonaceous adsorbents were compared. • Surface chemistry of the adsorbents controlled adsorption affinity. • Carbon surface basicity was positively correlated with the extent of PFOS and PFOA uptake. • Carbon polarity or hydrophobicity was not correlated with adsorption affinity. • Synthetic polymer-based adsorbents were more effective in removing PFOS and PFOA. - Carbon surface basicity is the primary factor that influences adsorption affinity of the carbonaceous sorbents for perfluorooctane sulfonic and carboxylic acids

  4. Plasma polymerization surface modification of Carbon black and its effect in elastomers

    NARCIS (Netherlands)

    Mathew, T.; Datta, Rabin; Dierkes, Wilma K.; Talma, Auke; Ooij, W.J.; Noordermeer, Jacobus W.M.

    2011-01-01

    Surface modification of carbon black by plasma polymerization was aimed to reduce its surface energy in order to compatibilize the filler with various elastomers. A fullerenic carbon black was used for the modification process. Thermogravimetric analysis, wetting behavior with liquids of known

  5. Convergent fabrication of a nanoporous two-dimensional carbon network from an aldol condensation on metal surfaces

    International Nuclear Information System (INIS)

    Landers, John; De Santis, Maurizio; Bendiab, Nedjma; Magaud, Laurence; Coraux, Johann; Chérioux, Frédéric; Lamare, Simon

    2014-01-01

    We report a convergent surface polymerization reaction scheme on Au(111), based on a triple aldol condensation, yielding a carbon-rich, covalent nanoporous two-dimensional network. The reaction is not self-poisoning and proceeds up to a full surface coverage. The deposited precursor molecules 1, 3, 5-tri(4’-acetylphenyl) first form supramolecular assemblies that are converted to the porous covalent network upon heating. The formation and structure of the network and of the intermediate steps are studied with scanning tunneling microscopy, Raman spectroscopy and density functional theory. (paper)

  6. Near-surface monitoring strategies for geologic carbon dioxide storage verification

    Energy Technology Data Exchange (ETDEWEB)

    Oldenburg, Curtis M.; Lewicki, Jennifer L.; Hepple, Robert P.

    2003-10-31

    Geologic carbon sequestration is the capture of anthropogenic carbon dioxide (CO{sub 2}) and its storage in deep geologic formations. Geologic CO{sub 2} storage verification will be needed to ensure that CO{sub 2} is not leaking from the intended storage formation and seeping out of the ground. Because the ultimate failure of geologic CO{sub 2} storage occurs when CO{sub 2} seeps out of the ground into the atmospheric surface layer, and because elevated concentrations of CO{sub 2} near the ground surface can cause health, safety, and environmental risks, monitoring will need to be carried out in the near-surface environment. The detection of a CO{sub 2} leakage or seepage signal (LOSS) in the near-surface environment is challenging because there are large natural variations in CO{sub 2} concentrations and fluxes arising from soil, plant, and subsurface processes. The term leakage refers to CO{sub 2} migration away from the intended storage site, while seepage is defined as CO{sub 2} passing from one medium to another, for example across the ground surface. The flow and transport of CO{sub 2} at high concentrations in the near-surface environment will be controlled by its high density, low viscosity, and high solubility in water relative to air. Numerical simulations of leakage and seepage show that CO{sub 2} concentrations can reach very high levels in the shallow subsurface even for relatively modest CO{sub 2} leakage fluxes. However, once CO{sub 2} seeps out of the ground into the atmospheric surface layer, surface winds are effective at dispersing CO{sub 2} seepage. In natural ecological systems with no CO{sub 2} LOSS, near-surface CO{sub 2} fluxes and concentrations are controlled by CO{sub 2} uptake by photosynthesis, and production by root respiration, organic carbon biodegradation in soil, deep outgassing of CO{sub 2}, and by exchange of CO{sub 2} with the atmosphere. Existing technologies available for monitoring CO{sub 2} in the near-surface environment

  7. Interfacial enhancement of carbon fiber/nylon 12 composites by grafting nylon 6 to the surface of carbon fiber

    Science.gov (United States)

    Hui, Chen; Qingyu, Cai; Jing, Wu; Xiaohong, Xia; Hongbo, Liu; Zhanjun, Luo

    2018-05-01

    Nylon 6 (PA6) grafted onto carbon fiber (CF) after chemical oxidation treatment was in an attempt to reinforce the mechanical properties of carbon fiber composites. Scanning electronic microscopy (SEM), Fourier transform infrared analysis (FT-IR), X-ray photoelectron spectroscope (XPS) and thermogravimetric analysis (TG) were selected to characterize carbon fibers with different surface treated. Experimental results showed that PA6 was grafted uniformly on the fiber surface through the anionic polymerization. A large number of functional groups were introduced to the fiber surface and the surface roughness was increased. After grafting PA6 on the oxidized carbon fibers, it played an important role on improving the interfacial adhesion between the fibers and the matrix by improving PA12 wettability, increasing chemical bonding and mechanical interlocking. Compared with the desized CF composites, the tensile strength of PA6-CF/PA12 composites was increased by 30.8% from 53.9 MPa to 70.2 MPa. All results indicated that grafting PA6 onto carbon fiber surface was an effective method to enhance the mechanical strength of carbon fiber/nylon 12 composites.

  8. Direct synthesis of sp-bonded carbon chains on graphite surface by femtosecond laser irradiation

    International Nuclear Information System (INIS)

    Hu, A.; Rybachuk, M.; Lu, Q.-B.; Duley, W. W.

    2007-01-01

    Microscopic phase transformation from graphite to sp-bonded carbon chains (carbyne) and nanodiamond has been induced by femtosecond laser pulses on graphite surface. UV/surface enhanced Raman scattering spectra and x-ray photoelectron spectra displayed the local synthesis of carbyne in the melt zone while nanocrystalline diamond and trans-polyacetylene chains form in the edge area of gentle ablation. These results evidence possible direct 'writing' of variable chemical bonded carbons by femtosecond laser pulses for carbon-based applications

  9. Final Report: Mechanisms of sputter ripple formation: coupling among energetic ions, surface kinetics, stress and composition

    Energy Technology Data Exchange (ETDEWEB)

    Chason, Eric; Shenoy, Vivek

    2013-01-22

    Self-organized pattern formation enables the creation of nanoscale surface structures over large areas based on fundamental physical processes rather than an applied template. Low energy ion bombardment is one such method that induces the spontaneous formation of a wide variety of interesting morphological features (e.g., sputter ripples and/or quantum dots). This program focused on the processes controlling sputter ripple formation and the kinetics controlling the evolution of surfaces and nanostructures in high flux environments. This was done by using systematic, quantitative experiments to measure ripple formation under a variety of processing conditions coupled with modeling to interpret the results.

  10. Kinetic response study in chemiresistive gas sensor based on carbon nanotube surface functionalized with substituted phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Anshul Kumar; Saini, Rajan; Bedi, R. K.; Mahajan, Aman, E-mail: dramanmahajan@yahoo.co.in, E-mail: anshulsharma.phy@gmail.com [Material Science Laboratory, Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Kumar, Pankaj [Department of Applied Sciences, I.K. Gujral Punjab Technical University, Kapurthala 144601 (India)

    2016-05-06

    A kind of hybrid material is prepared by functionalizing multi-wall carbon nanotubes (MWCNTs-COOH) with substituted copper phthalocyanine and the formation of CuPcOC{sub 8}/MWCNTs-COOH hybrid is confirmed by scanning electron microscopy and transmission electron microscopy. The results indicated that on the surface of nanotubes substituted CuPcOC{sub 8} derivatives has been successfully anchored through π-π stacking interaction. The gas sensing application of the fabricated hybrid material is tested upon exposure to different hazardous species, specifically NO{sub 2}, NO, Cl{sub 2} and NH{sub 3} at operating temperature of 150°C. It has been demonstrated that for Cl{sub 2} minimum detection limit of CuPcOC{sub 8}/MWCNTs-COOH hybrid is 100 ppb. The response of hybrid sensor is found to be increased with increase in the concentration of Cl{sub 2}.

  11. Kinetic response study in chemiresistive gas sensor based on carbon nanotube surface functionalized with substituted phthalocyanines

    Science.gov (United States)

    Sharma, Anshul Kumar; Kumar, Pankaj; Saini, Rajan; Bedi, R. K.; Mahajan, Aman

    2016-05-01

    A kind of hybrid material is prepared by functionalizing multi-wall carbon nanotubes (MWCNTs-COOH) with substituted copper phthalocyanine and the formation of CuPcOC8/MWCNTs-COOH hybrid is confirmed by scanning electron microscopy and transmission electron microscopy. The results indicated that on the surface of nanotubes substituted CuPcOC8 derivatives has been successfully anchored through π-π stacking interaction. The gas sensing application of the fabricated hybrid material is tested upon exposure to different hazardous species, specifically NO2, NO, Cl2 and NH3 at operating temperature of 150˚C. It has been demonstrated that for Cl2 minimum detection limit of CuPcOC8/MWCNTs-COOH hybrid is 100 ppb. The response of hybrid sensor is found to be increased with increase in the concentration of Cl2.

  12. Influence of the lithium salt nature over the surface film formation on a graphite electrode in Li-ion batteries: An XPS study

    International Nuclear Information System (INIS)

    Leroy, S.; Martinez, H.; Dedryvere, R.; Lemordant, D.; Gonbeau, D.

    2007-01-01

    The formation of a passivation film (solid electrolyte interphase, SEI) at the surface of the negative electrode of full LiCoO 2 /graphite lithium-ion cells using different salts (LiBF 4 , LiPF 6 , LiTFSI, LiBETI) in carbonate solvents as electrolyte was investigated by X-ray photoelectron spectroscopy (XPS). The analyzes were carried out at different potential stages of the first cycle, showing the potential-dependent character of the surface film species formation and the specificity of each salt. At 3.8 V, for all salts, we have mainly identified carbonated species. Beyond this potential, the specific behavior of LiPF 6 was identified with a high LiF deposit, whereas for other salts, the formation process of the SEI appears controlled by the solvent decomposition of the electrolyte

  13. Molecular hydrogen formation on surfaces of astrophysical interest: first results on water ice at very low temperature and on graphite at high temperature

    International Nuclear Information System (INIS)

    Baouche, Saoud

    2004-01-01

    As the generally admitted mechanism of formation of the H_2 molecule in the interstellar medium (ISM) is a catalytic reaction between two atoms of H on the surface of cosmic powder grains, where grains are supposed to be carbons or silicates and could have ice coats, this research thesis aims at providing some elements about the efficiency of this reaction, what happens to the bound energy released after formation of the H_2 molecule. The author first describes the FORMOLISM experiment (Formation of molecule in the ISM), and then reports the study of the source of H or D atoms which is a very important component of the experiment. He reports and comments results obtained on the formation of H_2 and D_2 molecules on amorphous water ice. He reports the study of the dynamics of formation of the D_2 molecule on a graphite surface by using the laser-aided associative adsorption technique

  14. Effect of heat treatment on carbon fiber surface properties and fibers/epoxy interfacial adhesion

    International Nuclear Information System (INIS)

    Dai Zhishuang; Zhang Baoyan; Shi Fenghui; Li Min; Zhang Zuoguang; Gu Yizhuo

    2011-01-01

    Carbon fiber surface properties are likely to change during the molding process of carbon fiber reinforced matrix composite, and these changes could affect the infiltration and adhesion between carbon fiber and resin. T300B fiber was heat treated referring to the curing process of high-performance carbon fiber reinforced epoxy matrix composites. By means of X-ray photoelectron spectroscopy (XPS), activated carbon atoms can be detected, which are defined as the carbon atoms conjunction with oxygen and nitrogen. Surface chemistry analysis shows that the content of activated carbon atoms on treated carbon fiber surface, especially those connect with the hydroxyl decreases with the increasing heat treatment temperature. Inverse gas chromatography (IGC) analysis reveals that the dispersive surface energy γ S d increases and the polar surface energy γ S sp decreases as the heat treatment temperature increases to 200. Contact angle between carbon fiber and epoxy E51 resin, which is studied by dynamic contact angle test (DCAT) increases with the increasing heat treatment temperature, indicating the worse wettability comparing with the untreated fiber. Moreover, micro-droplet test shows that the interfacial shear strength (IFSS) of the treated carbon fiber/epoxy is lower than that of the untreated T300B fiber which is attributed to the decrement of the content of reactive functional groups including hydrogen group and epoxy group.

  15. Modification of carbon fiber surfaces via grafting with Meldrum's acid

    International Nuclear Information System (INIS)

    Cuiqin, Fang; Jinxian, Wu; Julin, Wang; Tao, Zhang

    2015-01-01

    Graphical abstract: - Highlights: • The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated. • The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid. • The relative content of carboxylic groups on carbon fiber surfaces was increased. • The surfaces of carbon fibers neither etched nor generated coating. • Tensile strength of carbon fibers was preserved after grafting reaction. - Abstract: The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

  16. Modification of carbon fiber surfaces via grafting with Meldrum's acid

    Energy Technology Data Exchange (ETDEWEB)

    Cuiqin, Fang; Jinxian, Wu [Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing 100029 (China); Julin, Wang, E-mail: wjl@mail.buct.edu.cn [Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing 100029 (China); Tao, Zhang [Beijing Institute of Ancient Architecture, Beijing 100050 (China)

    2015-11-30

    Graphical abstract: - Highlights: • The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated. • The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid. • The relative content of carboxylic groups on carbon fiber surfaces was increased. • The surfaces of carbon fibers neither etched nor generated coating. • Tensile strength of carbon fibers was preserved after grafting reaction. - Abstract: The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

  17. Low-mass stars with mass loss and low-luminosity carbon star formation

    International Nuclear Information System (INIS)

    Boothroyd, A.I.

    1987-01-01

    The effects of large carbon enrichments in static stellar envelopes were investigated, using new Los Alamos opacities (including low-temperature carbon and molecular opacities) and including carbon ionizations. To search for the production of low-mass,low-luminosity carbon stars, detailed stellar evolutionary computations were carried out for a grid of low-mass stars of two different metallicities. The stars were evolved from the main sequence through all intermediate stages and through helium-shell flashes on the asymptotic giant branch. The effects of the latest nuclear reaction rates, the new Los Alamos opacities, Reimers-type wind mass loss, and detailed treatment of convection and semi-convection were investigated. Two low-luminosity carbon stars were achieved, in excellent agreement with observations. Conditions favoring dredge-up (and thus carbon-star production) include a reasonably large convective mixing length, low metallicity, relatively large envelope mass, and high flash strength. Mass loss was of major importance, tending to oppose dredge-up; the total mass-loss amounts inferred from observations suffice to prevent formation of high-mass, high-luminosity carbon stars

  18. Surface Passivation and Junction Formation Using Low Energy Hydrogen Implants

    Science.gov (United States)

    Fonash, S. J.

    1985-01-01

    New applications for high current, low energy hydrogen ion implants on single crystal and polycrystal silicon grain boundaries are discussed. The effects of low energy hydrogen ion beams on crystalline Si surfaces are considered. The effect of these beams on bulk defects in crystalline Si is addressed. Specific applications of H+ implants to crystalline Si processing are discussed. In all of the situations reported on, the hydrogen beams were produced using a high current Kaufman ion source.

  19. Surface Acoustic Wave (SAW Resonators for Monitoring Conditioning Film Formation

    Directory of Open Access Journals (Sweden)

    Siegfried Hohmann

    2015-05-01

    Full Text Available We propose surface acoustic wave (SAW resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM sensor measurements, which confirmed the suitability of the SAW resonators for this application.

  20. SURFACE ROUGHNESS AND CUTTING FORCES IN CRYOGENIC TURNING OF CARBON STEEL

    Directory of Open Access Journals (Sweden)

    T. C. YAP

    2015-07-01

    Full Text Available The effect of cryogenic liquid nitrogen on surface roughness, cutting forces, and friction coefficient of the machined surface when machining of carbon steel S45C in wet, dry and cryogenic condition was studied through experiments. The experimental results show that machining with liquid nitrogen increases the cutting forces, reduces the friction coefficient, and improves the chips produced. Beside this, conventional machining with cutting fluid is still the most suitable method to produce good surface in high speed machining of carbon steel S45C whereas dry machining produced best surface roughness in low speed machining. Cryogenic machining is not able to replace conventional cutting fluid in turning carbon steel.

  1. Influence of carbon monoxide to the surface layer of uranium metal and its oxides

    International Nuclear Information System (INIS)

    Wang Xiaoling; Fu Yibei; Xie Renshou; Huang Ruiliang

    1996-09-01

    The surface structures of uranium metal and triuranium octaoxide (U 3 O 8 ) and the influence of carbon monoxide to the surface layers have been studied by X-ray photoelectron spectroscopy (XPS). After exposure to carbon monoxide, contents of oxygen in the surface oxides of uranium metal and U 3 O 8 are decreased and O/U ratios decrease 7.2%, 8.0% respectively. The investigation indicated the surface layers of uranium metal and its oxides were forbidden to further oxidation in the atmosphere of carbon monoxide. (11 refs., 9 figs., 2 tabs.)

  2. Control of Surface Functional Groups on Pertechnetate Sorption on Activated Carbon

    International Nuclear Information System (INIS)

    Y. Wang; H. Gao; R. Yeredla; H. Xu; M. Abrecht; G.D. Stasio

    2006-01-01

    99 Tc is highly soluble and poorly adsorbed by natural materials under oxidizing conditions, thus being of particular concern for radioactive waste disposal. Activated carbon can potentially be used as an adsorbent for removing Tc from aqueous solutions. We have tested six commercial activated carbon materials for their capabilities for sorption of pertechnetate (TcO 4 - ). The tested materials can be grouped into two distinct types: Type I materials have high sorption capabilities with the distribution coefficients (K d ) varying from 9.5 x 10 5 to 3.2 x 10 3 mL/g as the pH changes from 4.5 to 9.5, whereas type II materials have relatively low sorption capabilities with K d remaining more or less constant (1.1 x 10 3 - 1.8 x 10 3 mL/g) over a similar pH range. The difference in sorption behavior between the two types of materials is attributed to the distribution of surface functional groups. The predominant surface groups are identified to be carboxylic and phenolic groups. The carboxylic group can be further divided into three subgroups A, B, and C in the order of increasing acidity. The high sorption capabilities of type I materials are found to be caused by the presence of a large fraction of carboxylic subgroups A and B, while the low sorption capabilities of type II materials are due to the exclusive presence of phenolic and carboxylic subgroup C. Therefore, the performance of activated carbon for removing TcO 4 - can be improved by enhancing the formation of carboxylic subgroups A and B during material processing

  3. Influence of activated carbon characteristics on toluene and hexane adsorption: Application of surface response methodology

    Science.gov (United States)

    Izquierdo, Mª Teresa; de Yuso, Alicia Martínez; Valenciano, Raquel; Rubio, Begoña; Pino, Mª Rosa

    2013-01-01

    The objective of this study was to evaluate the adsorption capacity of toluene and hexane over activated carbons prepared according an experimental design, considering as variables the activation temperature, the impregnation ratio and the activation time. The response surface methodology was applied to optimize the adsorption capacity of the carbons regarding the preparation conditions that determine the physicochemical characteristics of the activated carbons. The methodology of preparation produced activated carbons with surface areas and micropore volumes as high as 1128 m2/g and 0.52 cm3/g, respectively. Moreover, the activated carbons exhibit mesoporosity, ranging from 64.6% to 89.1% the percentage of microporosity. The surface chemistry was characterized by TPD, FTIR and acid-base titration obtaining different values of surface groups from the different techniques because the limitation of each technique, but obtaining similar trends for the activated carbons studied. The exhaustive characterization of the activated carbons allows to state that the measured surface area does not explain the adsorption capacity for either toluene or n-hexane. On the other hand, the surface chemistry does not explain the adsorption results either. A compromise between physical and chemical characteristics can be obtained from the appropriate activation conditions, and the response surface methodology gives the optimal activated carbon to maximize adsorption capacity. Low activation temperature, intermediate impregnation ratio lead to high toluene and n-hexane adsorption capacities depending on the activation time, which a determining factor to maximize toluene adsorption.

  4. Formation and fates of nitrosamines and their formation potentials from a surface water source to drinking water treatment plants in Southern Taiwan.

    Science.gov (United States)

    Chen, Wei-Hsiang; Wang, Chung-Ya; Huang, Tsung-Hsien

    2016-10-01

    Nitrosamines are toxic and emerging disinfection byproducts. In this study, three drinking water treatment plants (DWTPs) in southern Taiwan treating the same source water in Gaoping River with comparable technologies were selected. The objective was to evaluate the formation and fates of six nitrosamines and their formation potentials (FPs) from a surface water source to drinking water. Albeit decreased further downstream in the river, four nitrosamine-FPs were observed in the source water due to anthropogenic pollution in the upstream areas. In the DWTPs, nitrosamines were formed and NDMA was the main species. While high organic carbon concentrations indicated elevated nitrosamine-FPs in the source water, NDMA formation in the DWTPs was more positively associated with reductions of water parameters that quantify organic matters with double bonded ring structures. Although precursor removal via pre-oxidation is a viable approach to limit nitrosamine formation during post-disinfection, this study clearly indicates that a great portion of NDMA in treated water has been formed in the 1st oxidation step of drinking water treatment. The pre-oxidation simulations in the lab demonstrated the impact of pre-chlorination on nitrosamine formation. Given the limited removal in conventional treatment processes, avoiding nitrosamine-FPs in sources and/or nitrosamine formation during pre-oxidation become important issues to control the threats of nitrosamines in drinking water. Under current circumstance in which pre-oxidation is widely used to optimize the treatment effectiveness in many DWTPs, its adverse effect by forming nitrosamines needs to be carefully minimized and using technologies other than pre-chlorination (e.g., pre-ozonation) may be considered. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Influence of surface properties on the mechanism of H2S removal by alkaline activated carbons.

    Science.gov (United States)

    Yan, Rong; Chin, Terence; Ng, Yuen Ling; Duan, Huiqi; Liang, David Tee; Tay, Joo Hwa

    2004-01-01

    Alkaline activated carbons are widely used as adsorbents of hydrogen sulfide (H2S), one of the major odorous compounds arising from sewage treatment facilities. Although a number of studies have explored the effects of various parameters, mechanisms of H2S adsorption by alkaline carbons are not yet fully understood. The major difficulty seems to lie in the fact that little is known with certainty about the predominant reactions occurring on the carbon surface. In this study, the surface properties of alkaline activated carbons were systematically investigated to further exploit and better understand the mechanisms of H2S adsorption by alkaline activated carbons. Two commercially available alkaline activated carbons and their representative exhausted samples (8 samples collected at different height of the column after H2S breakthrough tests) were studied. The 8 portions of the exhausted carbon were used to represent the H2S/carbon reaction process. The surface properties of both the original and the exhausted carbons were characterized using the sorption of nitrogen (BET test), surface pH, Boehm titration, thermal and FTIR analysis. Porosity and surface area provide detailed information about the pore structure of the exhausted carbons with respect to the reaction extent facilitating the understanding of potential pore blockages. Results of Boehm titration and FTIR both demonstrate the significant effects of surface functional groups, and identification of oxidation products confirmed the different mechanisms involved with the two carbons. From the DTG curves of thermal analysis, two well-defined peaks representing two products of surface reactions (i.e., sulfur and sulfuric acid) were observed from the 8 exhausted portions with gradually changing patterns coinciding with the extent of the reaction. Surface pH values of the exhausted carbons show a clear trend of pH drop along the reaction extent, while pH around 2 was observed for the bottom of the bed indicating

  6. Deactivating Carbon Formation on a Ni/Al2O3 Catalyst under Methanation Conditions

    DEFF Research Database (Denmark)

    Olesen, Sine Ellemann; Andersson, Klas J.; Damsgaard, Christian Danvad

    2017-01-01

    . The longer the duration of the methanation test, the more carbon was built up on the Ni surfaces and the highest observed amount was quantified to be as much as eight carbon atoms per Ni surface atom (8 C/Nisurf), which would roughly correspond to an average coverage of four monolayers of graphene. From H2...... desorption measurements after reaction the 650 K TPH peak carbon structure is proposed to be partially hydrogenated, possibly resembling polycyclic aromatic-like carbon. The 775 K peak carbon species are likely more graphene-like. Results indicate that although carbon deposition nucleation may be initiated...

  7. Variation in stable carbon isotopes in organic matter from the Gunflint Iron Formation

    International Nuclear Information System (INIS)

    Barghoorn, E.S.; Knoll, A.H.; Dembicki, H. Jr.; Meinschein, W.G.

    1977-01-01

    In order to examine possible variations in organic carbon isotopic ratios within a single Precambrian formation, the kerogen separated from 15 samples of the approximately 2000 m.y. old Gunflint Iron Formation and the conformably overlying Rove Formation, representing a wide range of lithologies and geographic localities, was isotopically analyzed. From the resulting data, four conclusions can be drawn: (1) delta 13 C values of the shallow water algal chert facies are significantly more negative (-25 to -30 parts per thousand) than those of the deeper water chert-carbonate and taconite facies (-15 to -20 parts per thousand). Comparative data for modern marine algal mats shows a range of delta 13 C values from -8.4 to -19 parts per thousand PDB. Values obtained for fresh water mats were slightly more negative. (2) These differences in isotopic ratios can be correlated with similar differences in preserved microbiotas. (3) Anthraxolite lenses are depleted in 13 C relative to the reduced carbon in surrounding sediments. (4) The effect of Keweenawan diabase intrusions upon the carbon isotopic composition is pronounced, but limited to the immediate vicinity of the contact. (author)

  8. Carbon activation process for increased surface accessibility in electrochemical capacitors

    Science.gov (United States)

    Doughty, Daniel H.; Eisenmann, Erhard T.

    2001-01-01

    A process for making carbon film or powder suitable for double capacitor electrodes having a capacitance of up to about 300 F/cm.sup.3 is disclosed. This is accomplished by treating in aqueous nitric acid for a period of about 5 to 15 minutes thin carbon films obtained by carbonizing carbon-containing polymeric material having a high degree of molecular directionality, such as polyimide film, then heating the treated carbon film in a non-oxidizing atmosphere at a non-graphitizing temperature of at least 350.degree. C. for about 20 minutes, and repeating alternately the nitric acid step and the heating step from 7 to 10 times. Capacitors made with this carbon may find uses ranging from electronic devices to electric vehicle applications.

  9. Reactivity of polyester aliphatic amine surfactants as corrosion inhibitors for carbon steel in formation water (deep well water)

    International Nuclear Information System (INIS)

    Alsabagh, A.M.; Migahed, M.A.; Awad, Hayam S.

    2006-01-01

    Effect of different concentrations, 40-200 ppm, of various polyester aliphatic amine surfactants on inhibition of the corrosion of carbon steel in the formation water (deep well water) was investigated. These surfactants exhibit different levels of inhibition particularly at high concentration (200 ppm). Inhibition efficiencies in the range 86-96% were determined by weight loss method. Comparable results were obtained from electrochemical measurements using Tafel extrapolation and polarisation resistance methods. It was shown that all the investigated surfactants act primarily as anodic inhibitors; however, they also affect the rate and mechanism of the cathodic reaction. These compounds function via adsorption on reactive sites on the corroding surface reducing the corrosion rate of the metal. It was revealed that the adsorption of these surfactants obey Langmuir adsorption isotherm. The inhibition effectiveness increases with the length of the aliphatic hydrocarbon chain, being a maximum in the presence of surfactant IV (∼96% efficiency). The corrosion inhibition feature of this compound is attributed to the presence of a long hydrocarbon chain that ensures large surface coverage as well as the presence of multiple active centers for adsorption. Scanning electron microscopy, SEM, has been applied to identify the surface morphology of carbon steel alloy in the absence and presence of the inhibitor molecules

  10. Reactivity of polyester aliphatic amine surfactants as corrosion inhibitors for carbon steel in formation water (deep well water)

    Energy Technology Data Exchange (ETDEWEB)

    Alsabagh, A.M. [Department of Petroleum Applications, Egyptian Petroleum Research Institute (EPRI), Ahmed El-Zomor Street 1, Nasr City, Cairo 11727 (Egypt); Migahed, M.A. [Department of Petroleum Applications, Egyptian Petroleum Research Institute (EPRI), Ahmed El-Zomor Street 1, Nasr City, Cairo 11727 (Egypt)]. E-mail: mohamedatiyya707@hotmail.com; Awad, Hayam S. [Chemistry Department, Faculty of Girls for Science, Art and Education, Ain Shams University, Asmaa Fahmi Street, Helliopolis, Cairo (Egypt)

    2006-04-15

    Effect of different concentrations, 40-200 ppm, of various polyester aliphatic amine surfactants on inhibition of the corrosion of carbon steel in the formation water (deep well water) was investigated. These surfactants exhibit different levels of inhibition particularly at high concentration (200 ppm). Inhibition efficiencies in the range 86-96% were determined by weight loss method. Comparable results were obtained from electrochemical measurements using Tafel extrapolation and polarisation resistance methods. It was shown that all the investigated surfactants act primarily as anodic inhibitors; however, they also affect the rate and mechanism of the cathodic reaction. These compounds function via adsorption on reactive sites on the corroding surface reducing the corrosion rate of the metal. It was revealed that the adsorption of these surfactants obey Langmuir adsorption isotherm. The inhibition effectiveness increases with the length of the aliphatic hydrocarbon chain, being a maximum in the presence of surfactant IV ({approx}96% efficiency). The corrosion inhibition feature of this compound is attributed to the presence of a long hydrocarbon chain that ensures large surface coverage as well as the presence of multiple active centers for adsorption. Scanning electron microscopy, SEM, has been applied to identify the surface morphology of carbon steel alloy in the absence and presence of the inhibitor molecules.

  11. Low-cost formation of bulk and localized polymer-derived carbon nanodomains from polydimethylsiloxane.

    Science.gov (United States)

    Alcántara, Juan Carlos Castro; Cerda Zorrilla, Mariana; Cabriales, Lucia; Rossano, Luis Manuel León; Hautefeuille, Mathieu

    2015-01-01

    We present two simple alternative methods to form polymer-derived carbon nanodomains in a controlled fashion and at low cost, using custom-made chemical vapour deposition and selective laser ablation with a commercial CD-DVD platform. Both processes presented shiny and dark residual materials after the polymer combustion and according to micro-Raman spectroscopy of the domains, graphitic nanocrystals and carbon nanotubes have successfully been produced by the combustion of polydimethylsiloxane layers. The fabrication processes and characterization of the byproduct materials are reported. We demonstrate that CVD led to bulk production of graphitic nanocrystals and single-walled carbon nanotubes while direct laser ablation may be employed for the formation of localized fluorescent nanodots. In the latter case, graphitic nanodomains and multi-wall carbon nanotubes are left inside microchannels and preliminary results seem to indicate that laser ablation could offer a tuning control of the nature and optical properties of the nanodomains that are left inside micropatterns with on-demand geometries. These low-cost methods look particularly promising for the formation of carbon nanoresidues with controlled properties and in applications where high integration is desired.

  12. Bacterial adhesion and biofilm formation on surfaces of variable roughness and hydrophobicity

    DEFF Research Database (Denmark)

    Tang, Lone; Pillai, Saju; Iversen, Anders

    L.Biofilm formation on surfaces in food production and processing can deteriorate the quality of food products and be a hazard to consumers. The food industry currently uses a number of approaches to either remove biofilm or prevent its formation. Due to the inherent resilience of bacteria...... in biofilm, a particularly attractive approach is the modification of surfaces with the aim to impede the first step in biofilm formation, namely bacterial adhesion. Surface properties such as hydrophobicity, roughness and predisposition for fouling by protein are recognised as important in bacterial...... adhesion. Sol-gel technology and the recent availability of organic modified silicas have lead to development of hybrid organic/inorganic glass ceramic coatings with specialised surface properties. In this study we investigate bacterial adhesion and the subsequent biofilm formation on stainless steel (SS...

  13. Interaction between carbon fibers and polymer sizing: Influence of fiber surface chemistry and sizing reactivity

    Science.gov (United States)

    Moosburger-Will, Judith; Bauer, Matthias; Laukmanis, Eva; Horny, Robert; Wetjen, Denise; Manske, Tamara; Schmidt-Stein, Felix; Töpker, Jochen; Horn, Siegfried

    2018-05-01

    Different aspects of the interaction of carbon fibers and epoxy-based polymer sizings are investigated, e.g. the wetting behavior, the strength of adhesion between fiber and sizing, and the thermal stability of the sizing layer. The influence of carbon fiber surface chemistry and sizing reactivity is investigated using fibers of different degree of anodic oxidation and sizings with different number of reactive epoxy groups per molecule. Wetting of the carbon fibers by the sizing dispersion is found to be specified by both, the degree of fiber activation and the sizing reactivity. In contrast, adhesion strength between fibers and sizing is dominated by the surface chemistry of the carbon fibers. Here, the number of surface oxygen groups seems to be the limiting factor. We also find that the sizing and the additional functionalities induced by anodic oxidation are removed by thermal treatment at 600 °C, leaving the carbon fiber in its original state after carbonization.

  14. The research on the interfacial compatibility of polypropylene composite filled with surface treated carbon fiber

    International Nuclear Information System (INIS)

    Li, J.

    2009-01-01

    Dielectric barrier discharges (DBD) in ambient air are used on carbon fiber to improve the fiber surface activity. Carbon fibers with length of 75 μm are placed into the plasma configuration. The interaction between modified carbon fibers and polypropylene (PP) was studied by three-point bending (TPB) test. The chemical changes induced by the treatments on carbon fiber surface are examined using X-ray photoelectron spectroscopy (XPS). XPS results reveal that the carbon fiber modified with the DBD at atmospheric pressure show a significant increase in oxygen and nitrogen concentration. These results demonstrate that the surface of the carbon fiber is more active and hydrophilic after plasma treatments using a DBD operating in ambient air.

  15. On the mechanism of water cluster-ion formation in carbon dioxide

    International Nuclear Information System (INIS)

    Warneck, P.; Rakshit, A.B.

    1981-01-01

    A drift chamber mass spectrometer has been used to study the formation of water cluster-ions in carbon dioxide containing traces of water vapour. The dominant reaction sequences were identified up to the fourth generation of daughter ions starting with CO 2 + . The subsequent reaction mechanism remains uncertain and several possibilities are discussed. The final ions are H 3 O + H 2 O and H 3 O + (H 2 O) 2 . The significance of the reaction schemes to the radiation chemistry of carbon dioxide is pointed out. (orig.)

  16. In-situ observations of catalyst dynamics during surface-bound carbon nanotube nucleation

    DEFF Research Database (Denmark)

    Hofmann, S; Sharma, R; Du, G

    2007-01-01

    nanoparticles on SiOx support show crystalline lattice fringe contrast and high deformability before and during nanotube formation. A single-walled carbon nanotube nucleates by lift-off of a carbon cap. Cap stabilization and nanotube growth involve the dynamic reshaping of the catalyst nanocrystal itself...

  17. Biofilm formation by Listeria monocytogenes on stainless steel surface and biotransfer potential

    OpenAIRE

    Oliveira,Maíra Maciel Mattos de; Brugnera,Danilo Florisvaldo; Alves,Eduardo; Piccoli,Roberta Hilsdorf

    2010-01-01

    An experimental model was proposed to study biofilm formation by Listeria monocytogenes ATCC 19117 on AISI 304 (#4) stainless steel surface and biotransfer potential during this process. In this model, biofilm formation was conducted on the surface of stainless steel coupons, set on a stainless steel base with 4 divisions, each one supporting 21 coupons. Trypic Soy Broth was used as bacterial growth substrate, with incubation at 37 ?C and stirring of 50 rpm. The number of adhered cells was de...

  18. Evidence of hot spot formation on carbon limiters due to thermal electron emission

    International Nuclear Information System (INIS)

    Philipps, V.; Samm, U.; Tokar, M.Z.; Unterberg, B.; Pospieszczyk, A.; Schweer, B.

    1993-01-01

    Carbon test limiters have been exposed in TEXTOR to high heat loads up to about 30 MW/m 2 . The evolutions of the surface temperature distribution and of the carbon release have been observed by means of local diagnostics. A sudden acceleration of the rise of the surface temperature has been found at a critical temperature of approx. 2400 deg. C. The increase of the rate of the temperature rise is consistent with an enhancement of the power loading by a factor of 2.5-3. Following the temperature jump (hot spot), a quasi-equilibrium temperature establishes at approx. 2700 deg. C. The development of the hot spot is explained by an increase of the local power loading to the breakdown of the sheath potential by thermal emission of electrons from the carbon surface. Simultaneously with the appearance of the hot spot, the carbon release from the surface increases sharply. This increase can be explained by normal thermal sublimation. Sublimation cooling contributes to the establishment of the quasi-equilibrium temperature at about 2700 deg. C. (author). 16 refs, 10 figs

  19. Surface functionalization of carbon nanofibers by sol-gel coating of zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Shao Dongfeng [Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi 214122 (China); Changzhou Textile Garment Institute, Changzhou 213164 (China); Wei Qufu [Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi 214122 (China)], E-mail: qfwei@jiangnan.edu.cn; Zhang Liwei; Cai Yibing; Jiang Shudong [Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi 214122 (China)

    2008-08-15

    In this paper the functional carbon nanofibers were prepared by the carbonization of ZnO coated PAN nanofibers to expand the potential applications of carbon nanofibers. Polyacrylonitrile (PAN) nanofibers were obtained by electrospinning. The electrospun PAN nanofibers were then used as substrates for depositing the functional layer of zinc oxide (ZnO) on the PAN nanofiber surfaces by sol-gel technique. The effects of coating, pre-oxidation and carbonization on the surface morphology and structures of the nanofibers were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Scanning electron microscopy (SEM), respectively. The results of SEM showed a significant increase of the size of ZnO nanograins on the surface of nanofibers after the treatments of coating, pre-oxidation and carbonization. The observations by SEM also revealed that ZnO nanoclusters were firmly and clearly distributed on the surface of the carbon nanofibers. FTIR examination also confirmed the deposition of ZnO on the surface of carbon nanofibers. The XRD analysis indicated that the crystal structure of ZnO nanograins on the surface of carbon nanofibers.

  20. Porous carbon with a large surface area and an ultrahigh carbon purity via templating carbonization coupling with KOH activation as excellent supercapacitor electrode materials

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Fei; Gao, Jihui, E-mail: gaojh@hit.edu.cn; Liu, Xin; Pi, Xinxin; Yang, Yuqi; Wu, Shaohua

    2016-11-30

    Highlights: • Simple templating carbonization method was developed to obtain porous carbons. • Surface etching by KOH activation greatly boosts surface area and carbon purity. • The as-obtained porous carbon delivers a high capacitance of 275 F g{sup −1}. • Symmetric supercapacitor can achieved high energy density and power density. - Abstract: Large surface area and good structural stability, for porous carbons, are two crucial requirements to enable the constructed supercapacitors with high capacitance and long cycling lifespan. Herein, we successfully prepare porous carbon with a large surface area (3175 m{sup 2} g{sup −1}) and an ultrahigh carbon purity (carbon atom ratio of 98.25%) via templating carbonization coupling with KOH activation. As-synthesized MTC-KOH exhibits excellent performances as supercapacitor electrode materials in terms of high specific capacitance and ultrahigh cycling stability. In a three electrode system, MTC-KOH delivers a high capacitance of 275 F g{sup −1} at 0.5 A g{sup −1} and still 120 F g{sup −1} at a high rate of 30 A g{sup −1}. There is almost no capacitance decay even after 10,000 cycles, demonstrating outstanding cycling stability. In comparison, pre-activated MTC with a hierarchical pore structure shows a better rate capability than microporous MTC-KOH. Moreover, the constructed symmetric supercapacitor using MTC-KOH can achieve high energy densities of 8.68 Wh kg{sup −1} and 4.03 Wh kg{sup −1} with the corresponding power densities of 108 W kg{sup −1} and 6.49 kW kg{sup −1}, respectively. Our work provides a simple design strategy to prepare highly porous carbons with high carbon purity for supercapacitors application.

  1. Porous carbon with a large surface area and an ultrahigh carbon purity via templating carbonization coupling with KOH activation as excellent supercapacitor electrode materials

    International Nuclear Information System (INIS)

    Sun, Fei; Gao, Jihui; Liu, Xin; Pi, Xinxin; Yang, Yuqi; Wu, Shaohua

    2016-01-01

    Highlights: • Simple templating carbonization method was developed to obtain porous carbons. • Surface etching by KOH activation greatly boosts surface area and carbon purity. • The as-obtained porous carbon delivers a high capacitance of 275 F g −1 . • Symmetric supercapacitor can achieved high energy density and power density. - Abstract: Large surface area and good structural stability, for porous carbons, are two crucial requirements to enable the constructed supercapacitors with high capacitance and long cycling lifespan. Herein, we successfully prepare porous carbon with a large surface area (3175 m 2 g −1 ) and an ultrahigh carbon purity (carbon atom ratio of 98.25%) via templating carbonization coupling with KOH activation. As-synthesized MTC-KOH exhibits excellent performances as supercapacitor electrode materials in terms of high specific capacitance and ultrahigh cycling stability. In a three electrode system, MTC-KOH delivers a high capacitance of 275 F g −1 at 0.5 A g −1 and still 120 F g −1 at a high rate of 30 A g −1 . There is almost no capacitance decay even after 10,000 cycles, demonstrating outstanding cycling stability. In comparison, pre-activated MTC with a hierarchical pore structure shows a better rate capability than microporous MTC-KOH. Moreover, the constructed symmetric supercapacitor using MTC-KOH can achieve high energy densities of 8.68 Wh kg −1 and 4.03 Wh kg −1 with the corresponding power densities of 108 W kg −1 and 6.49 kW kg −1 , respectively. Our work provides a simple design strategy to prepare highly porous carbons with high carbon purity for supercapacitors application.

  2. 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)

  3. Adaptive Fuzzy Output Regulation for Formation Control of Unmanned Surface Vehicles

    DEFF Research Database (Denmark)

    Li, Shaobao; Er, Meng Joo; Wang, Ning

    2017-01-01

    In this paper, the formation control problem of unmanned surface vehicles (USVs) is investigated. Unlike the classical formation control problem where the reference signal is required to be second-order differentiable with respect to time, we consider a more general autonomous dynamic system...

  4. Method and system for formation and withdrawal of a sample from a surface to be analyzed

    Science.gov (United States)

    Van Berkel, Gary J.; Kertesz, Vilmos

    2017-10-03

    A method and system for formation and withdrawal of a sample from a surface to be analyzed utilizes a collection instrument having a port through which a liquid solution is conducted onto the surface to be analyzed. The port is positioned adjacent the surface to be analyzed, and the liquid solution is conducted onto the surface through the port so that the liquid solution conducted onto the surface interacts with material comprising the surface. An amount of material is thereafter withdrawn from the surface. Pressure control can be utilized to manipulate the solution balance at the surface to thereby control the withdrawal of the amount of material from the surface. Furthermore, such pressure control can be coordinated with the movement of the surface relative to the port of the collection instrument within the X-Y plane.

  5. Parameterizing A Surface Water Model for Multiwalled Carbon Nanotubes

    Science.gov (United States)

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

  6. Formation, transformation and dissolution of phases formed on surfaces

    International Nuclear Information System (INIS)

    Shoesmith, D.W.

    1983-03-01

    The basic mechanisms of film growth, transformation, and dissolution of phases formed on surfaces are discussed. Film growth can occur via solid-state processes or via substrate (usally metal or alloy) dissolution, followed by local supersaturation and precipitation of an insoluble phase. The phase(s) formed may be metastable and transform to a more stable phase, via either solid-state or dissolution-reprecipitation processes. Film dissolution reactions can also occur via a variety of mechanisms, including: (i) direct chemical dissolution when no oxidation state change occurs; (ii) redox dissolution when the film dissolves via a redox reaction involving a reducing or oxidizing agent in solution; and (iii) autoreduction, where film dissolution is coupled to metal dissolution. Such film-growth and dissolution processes, which often produce complex multilayer films, are common in the nuclear industry. A number of examples are discussed

  7. Mechanisms for formation and disruption of surface oxides: Final report

    International Nuclear Information System (INIS)

    Lumsden, J.B.

    1987-08-01

    Mill-annealed alloys 600, 690 and 800 were exposed to 10 and 50% caustic solutions containing 1% Na 2 CO 3 to initiate IGA. IGA reproducibly occurred in all three alloys in the 10% caustic solution at 350 0 C after a 240 h exposure and in the 50% caustic solution at 320 0 C after a 120 h exposure. Reproducible IGA did not occur in the 10% caustic solution at 320 0 C after a 120 h exposure. IGA was not observed in mill annealed plus thermally treated alloys 600 and 690 after exposure to any of the test conditions. IGA initiation was correlated with a dealloying mechanism in which the more active alloying metals, iron and chromium, selectively dissolve. Boric acid and calcium hydroxide additives were found to slow or prevent IGA by inhibiting dealloying. Titanates prevented IGA in alloys 600, 690 and 800, passivating the surface with a nickel titanate film

  8. Visualization of red-ox proteins on the gold surface using enzymatic polypyrrole formation

    International Nuclear Information System (INIS)

    Ramanaviciene, A.; Kausaite-Minkstimiene, A.; Voronovic, J.; Ramanavicius, A.; Oztekin, Y.; Carac, G.; German, N.

    2011-01-01

    We describe a new method for the visualization of the activity of red-ox proteins on a gold interface. Glucose oxidase was selected as a model system. Surfaces were modified by adhesion of glucose oxidase on (a) electrochemically cleaned gold; (b) gold films modified with gold nanoparticles, (c) a gold surface modified with self-assembled monolayer, and (d) covalent immobilization of protein on the gold surface modified with a self-assembled monolayer. The simple optical method for the visualization of enzyme on the surfaces is based on the enzymatic formation of polypyrrole. The activity of the enzyme was quantified via enzymatic formation of polypyrrole, which was detected and investigated by quartz microbalance and amperometric techniques. The experimental data suggest that the enzymatic formation of the polymer may serve as a method to indicate the adhesion of active redox enzyme on such surfaces. (author)

  9. Screen-printed carbon electrode modified on its surface with amorphous carbon nitride thin film: Electrochemical and morphological study

    Energy Technology Data Exchange (ETDEWEB)

    Ghamouss, F. [Universite de Nantes, UMR 6006-CNRS, FR-2465-CNRS, Laboratoire d' Analyse isotopique et Electrochimique de Metabolismes (LAIEM) (France); Tessier, P.-Y. [Universite de Nantes, UMR CNRS 6502, Institut des Materiaux Jean Rouxel - IMN Faculte des Sciences and des Techniques de Nantes, 2 rue de la Houssiniere, 44322 Nantes Cedex 3 (France); Djouadi, A. [Universite de Nantes, UMR CNRS 6502, Institut des Materiaux Jean Rouxel - IMN Faculte des Sciences and des Techniques de Nantes, 2 rue de la Houssiniere, 44322 Nantes Cedex 3 (France); Besland, M.-P. [Universite de Nantes, UMR CNRS 6502, Institut des Materiaux Jean Rouxel - IMN Faculte des Sciences and des Techniques de Nantes, 2 rue de la Houssiniere, 44322 Nantes Cedex 3 (France); Boujtita, M. [Universite de Nantes, UMR 6006-CNRS, FR-2465-CNRS, Laboratoire d' Analyse isotopique et Electrochimique de Metabolismes (LAIEM) (France)]. E-mail: mohammed.boujtita@univ-nantes.fr

    2007-04-20

    The surface of a screen-printed carbon electrode (SPCE) was modified by using amorphous carbon nitride (a-CN {sub x}) thin film deposited by reactive magnetron sputtering. Scanning electron microscopy and photoelectron spectroscopy measurements were used to characterise respectively the morphology and the chemical structure of the a-CN {sub x} modified electrodes. The incorporation of nitrogen in the amorphous carbon network was demonstrated by X ray photoelectron spectroscopy. The a-CN {sub x} layers were deposited on both carbon screen-printed electrode (SPCE) and silicon (Si) substrates. A comparative study showed that the nature of substrate, i.e. SPCE and Si, has a significant effect on both the surface morphology of deposited a-CN {sub x} film and their electrochemical properties. The improvement of the electrochemical reactivity of SPCE after a-CN {sub x} film deposition was highlighted both by comparing the shapes of voltammograms and calculating the apparent heterogeneous electron transfer rate constant.

  10. The aqueous electrochemistry of carbon-based surfaces-investigation by scanning tunneling microscopy

    Science.gov (United States)

    Mühl, T.; Myhra, S.

    2007-04-01

    Electro-oxidation of carbon-based materials will lead to conversion of the solid to CO2/CO at the anode, with H2 being produced at the cathode. Recent voltammetric investigations of carbon nano-tubes and single crystal graphite have shown that only edge sites and other defect sites are electrochemically active. Local oxidation of diamond-like carbon films (DLC) by an STM tip in moist air followed by imaging allows correlation of topographical change with electro-chemical conditions and surface reactivity. The results may have implications for lithographic processing of carbon surfaces, and may have relevance for electrochemical H2 production.

  11. TXRF study of electrochemical deposition of metals on glass-ceramic carbon electrode surfaces

    International Nuclear Information System (INIS)

    Alov, N.; Oskolok, K.; Wittershagen, A.; Mertens, M.; Rittmeyer, C.; Kolbesen, B.O.

    2000-01-01

    Nowadays the methods of solid surface analysis are widely used to study the thermodynamic and kinetic aspects of joint electrochemical deposition of metals on solid substrates. In this work the surfaces of some binary and ternary metal electrodeposits on disc glass-ceramic carbon electrodes were studied by total-reflection x-ray fluorescence spectroscopy (TXRF). Metal alloys were obtained as a result of electrochemical co-deposition of copper, cadmium and lead from n x 10 -4 M (Cu, Cd, Pb)(NO 3 ) 2 + 0.01 M HNO 3 solutions under mixing. TXRF measurements were performed with an ATOMIKA EXTRA II A spectrometer using Mo K α and W (Brems) primary excitation. The serious advantage of TXRF as a method of near-surface analysis is very high element sensitivity. Apart from main elements (Cu, Cd, Pb) we have detected trace elements (Cl, Ag, Pt, Hg) which are present in working solution and has an effect to the electrodeposit formation. The comparison of TXRF data with information obtained by X-ray photoelectron spectroscopy and electron-probe x-ray microanalysis permits to realize depth profiling electrochemical alloys. In particular it was found that in binary systems Cu-Pb and Cu-Cd the relative lead and cadmium content on the electrodeposit surface is considerably greater than in the bulk. These phenomena are due to the features of metal nucleation and growth mechanisms. High sensitivity of TXRF to surface morphology and the correlation of TXRF and scanning electron microscopy data allow to determine the area of prevailing location of metal in the heterogeneous alloy surface. So we have established that in Cu-Pb and Cu-Cd-Pb systems solid solution of copper and lead is formed: significant part of lead is deposited not only in specific 3D-clusters but also in copper thin film. It was demonstrated that the near-surface TXRF analysis of metal electrodeposits on solid electrodes is highly effective to study the mechanisms of metal nucleation, metal cluster and thin film

  12. Formation of carbon nanosheets via simultaneous activation and catalytic carbonization of macroporous anion-exchange resin for supercapacitors application.

    Science.gov (United States)

    Peng, Hui; Ma, Guofu; Sun, Kanjun; Mu, Jingjing; Zhang, Zhe; Lei, Ziqiang

    2014-12-10

    Two-dimensional mesoporous carbon nanosheets (CNSs) have been prepared via simultaneous activation and catalytic carbonization route using macroporous anion-exchange resin (AER) as carbon precursor and ZnCl2 and FeCl3 as activating agent and catalyst, respectively. The iron catalyst in the skeleton of the AER may lead to carburization to form a sheetlike structure during the carbonization process. The obtained CNSs have a large number of mesopores, a maximum specific surface area of 1764.9 m(2) g(-1), and large pore volume of 1.38 cm(3) g(-1). As an electrode material for supercapacitors application, the CNSs electrode possesses a large specific capacitance of 283 F g(-1) at 0.5 A g(-1) and excellent rate capability (64% retention ratio even at 50 A g(-1)) in 6 mol L(-1) KOH. Furthermore, CNSs symmetric supercapacitor exhibits specific energies of 17.2 W h kg(-1) at a power density of 224 W kg(-1) operated in the voltage range of 0-1.8 V in 0.5 mol L(-1) Na2SO4 aqueous electrolyte, and outstanding cyclability (retains about 96% initial capacitance after 5000 cycles).

  13. Multi-Walled Carbon Nanotube Coating on Alkali Treated TiO2 Nanotubes Surface for Improvement of Biocompatibility

    Directory of Open Access Journals (Sweden)

    Jung-Eun Park

    2018-04-01

    Full Text Available The aim of this study is to enhance the bioactivity of pure titanium using multiple surface treatments for the application of the implant. To form the biofunctional multilayer coating on pure titanium, anodization was conducted to make titanium dioxide nanotubes, then multi-walled carbon nanotubes were coated using a dipping method after an alkali treatment. The surface characteristics at each step were analyzed using a field emission scanning electron microscope and X-ray diffractometer. The effect of the multilayer coating on the biocompatibility was identified using immersion and cytotoxicity tests. Better hydroxyapatite formation was observed on the surface of multilayer-coated pure titanium compared to non-treated pure titanium after immersion in the simulated body fluid. Improvement of biocompatibility by multiple surface treatments was identified through various cytotoxicity tests using osteoblast cells.

  14. Influence of surface defects on the tensile strength of carbon fibers

    Science.gov (United States)

    Vautard, F.; Dentzer, J.; Nardin, M.; Schultz, J.; Defoort, B.

    2014-12-01

    The mechanical properties of carbon fibers, especially their tensile properties, are affected by internal and surface defects. In order to asses in what extent the generation of surface defects can result in a loss of the mechanical properties, non-surface treated carbon fibers were oxidized with three different surface treatment processes: electro-chemical oxidation, oxidation in nitric acid, and oxidation in oxygen plasma. Different surface topographies and surface chemistries were obtained, as well as different types and densities of surface defects. The density of surface defects was measured with both a physical approach (Raman spectroscopy) and a chemical approach (Active Surface Area). The tensile properties were evaluated by determining the Weibull modulus and the scale parameter of each reference, after measuring the tensile strength for four different gauge lengths. A relationship between the tensile properties and the nature and density of surface defects was noticed, as large defects largely control the value of the tensile strength. When optimized, some oxidation surface treatment processes can generate surface functional groups as well as an increase of the mechanical properties of the fibers, because of the removal of the contamination layer of pyrolytic carbon generated during the carbonization of the polyacrylonitrile precursor. Oxidation in oxygen plasma revealed to be a promising technology for alternative surface treatment processes, as high levels of functionalization were achieved and a slight improvement of the mechanical properties was obtained too.

  15. Chicken Juice Enhances Surface Attachment and Biofilm Formation of Campylobacter jejuni

    Science.gov (United States)

    Brown, Helen L.; Reuter, Mark; Salt, Louise J.; Cross, Kathryn L.; Betts, Roy P.

    2014-01-01

    The bacterial pathogen Campylobacter jejuni is primarily transmitted via the consumption of contaminated foodstuffs, especially poultry meat. In food processing environments, C. jejuni is required to survive a multitude of stresses and requires the use of specific survival mechanisms, such as biofilms. An initial step in biofilm formation is bacterial attachment to a surface. Here, we investigated the effects of a chicken meat exudate (chicken juice) on C. jejuni surface attachment and biofilm formation. Supplementation of brucella broth with ≥5% chicken juice resulted in increased biofilm formation on glass, polystyrene, and stainless steel surfaces with four C. jejuni isolates and one C. coli isolate in both microaerobic and aerobic conditions. When incubated with chicken juice, C. jejuni was both able to grow and form biofilms in static cultures in aerobic conditions. Electron microscopy showed that C. jejuni cells were associated with chicken juice particulates attached to the abiotic surface rather than the surface itself. This suggests that chicken juice contributes to C. jejuni biofilm formation by covering and conditioning the abiotic surface and is a source of nutrients. Chicken juice was able to complement the reduction in biofilm formation of an aflagellated mutant of C. jejuni, indicating that chicken juice may support food chain transmission of isolates with lowered motility. We provide here a useful model for studying the interaction of C. jejuni biofilms in food chain-relevant conditions and also show a possible mechanism for C. jejuni cell attachment and biofilm initiation on abiotic surfaces within the food chain. PMID:25192991

  16. Transformation Stasis Phenomenon of Bainite Formation in Low-Carbon, Multicomponent Alloyed Steel

    Science.gov (United States)

    Lan, Liangyun; Kong, Xiangwei

    2017-11-01

    The transformation stasis phenomenon of bainite formation in low-carbon steel was detected using a high-resolution dilatometer. The phenomenon occurred at different stages for different isothermal temperatures. In combination with microstructural observation, the calculated overall activation energy of transformation and interface migration velocity shed new light on the cause of formation of the stasis phenomenon. The temporary stasis formed at the initial stage of phase transformation for high isothermal temperature was attributed to the drag effect of substitutional atoms, which leads to low-interface migration velocity and large overall activation energy.

  17. Correlation and prediction of ion exchange equilibria on weak-acid resins by means of the surface complex formation model

    International Nuclear Information System (INIS)

    Horst, J.

    1988-11-01

    The present work summarizes investigations of the equilibrium of the exchange of protons, copper, zinc, calcium, magnesium and sodium ions on two weak-acid exchange resins in hydrochloric and carbonic acid bearing solutions at 25 0 C. The description of the state of equilibrium between resin and solution is based on the individual chemical equilibria which have to be adjusted simultaneously. The equilibrium in the liquid phase is described by the mass action law and the condition of electroneutrality using activity coefficients calculated according to the theory of Debye and Hueckel. The exchange equilibria are described by means of a surface complex formation model, which was developed by Davis, James and Leckie for activated aluminia and which has been applied to weak-acid resins. The model concept assumes the resin as a plane surface in which the functional groups are distributed uniformly. (orig./RB) [de

  18. Formation mechanism of spheroidal carbide in ultra-low carbon ductile cast iron

    Directory of Open Access Journals (Sweden)

    Bin-guo Fu

    2016-09-01

    Full Text Available The formation mechanism of the spheroidal carbide in the ultra-low carbon ductile cast iron fabricated by the metal mold casting technique was systematically investigated. The results demonstrated that the spheroidal carbide belonged to eutectic carbide and crystallized in the isolated eutectic liquid phase area. The formation process of the spheroidal carbide was related to the contact and the intersection between the primary dendrite and the secondary dendrite of austenite. The oxides of magnesium, rare earths and other elements can act as heterogeneous nucleation sites for the spheroidal carbide. It was also found that the amount of the spheroidal carbide would increase with an increase in carbon content. The cooling rate has an important influence on the spheroidal carbide under the same chemical composition condition.

  19. Enhancement of the oxidation resistance of carbon fibres in C/C composites via surface treatments

    Energy Technology Data Exchange (ETDEWEB)

    Labruquere, S.; Pailler, R.; Naslain, R. [Bordeaux Univ., Pessac (France). Lab. des Composites Thermostructuraux; Desbat, B. [Lab. de Spectroscopie Moleculaire et Cristalline, Univ. of Bordeaux, Talence (France)

    1997-12-31

    Carbon-carbon (C/C) composites are commonly used in rockets and braking systems. However, the carbon reacts with oxygen, burning away rapidly at temperatures as low as 450 C. This work deals with the protection of carbon fibres from oxidation between 600 and 1000 C. Two kinds of methods were investigated to protect carbon fibres: (i) surface treatment with aqueous solutions (e.g. of H3PO4) and (ii) chemical vapour deposition (CVD) of SiC coatings. Oxidation resistance of the as treated preforms was studied under dry air atmosphere. (orig.) 2 refs.

  20. Converting biomass waste into microporous carbon with simultaneously high surface area and carbon purity as advanced electrochemical energy storage materials

    Science.gov (United States)

    Sun, Fei; Wang, Lijie; Peng, Yiting; Gao, Jihui; Pi, Xinxin; Qu, Zhibin; Zhao, Guangbo; Qin, Yukun

    2018-04-01

    Developing carbon materials featuring both high accessible surface area and high structure stability are desirable to boost the performance of constructed electrochemical electrodes and devices. Herein, we report a new type of microporous carbon (MPC) derived from biomass waste based on a simple high-temperature chemical activation procedure. The optimized MPC-900 possesses microporous structure, high surface area, partially graphitic structure, and particularly low impurity content, which are critical features for enhancing carbon-based electrochemical process. The constructed MPC-900 symmetric supercapacitor exhibits high performances in commercial organic electrolyte such as widened voltage window up to 3 V and thereby high energy/power densities (50.95 Wh kg-1 at 0.44 kW kg-1; 25.3 Wh kg-1 at 21.5 kW kg-1). Furthermore, a simple melt infiltration method has been employed to enclose SnO2 nanocrystals onto the carbon matrix of MPC-900 as a high-performance lithium storage material. The obtained SnO2-MPC composite with ultrafine SnO2 nanocrystals delivers high capacities (1115 mAh g-1 at 0.2 A g-1; 402 mAh g-1 at 10 A g-1) and high-rate cycling lifespan of over 2000 cycles. This work not only develops a microporous carbon with high carbon purity and high surface area, but also provides a general platform for combining electrochemically active materials.

  1. Field Demonstration of Carbon Dioxide Miscible Flooding in the Lansing-Kansas City Formation, Central Kansas

    Energy Technology Data Exchange (ETDEWEB)

    Alan Byrnes; G. Paul Willhite; Don Green; Richard Pancake; JyunSyung Tsau; W. Lynn Watney; John Doveton; Willard Guy; Rodney Reynolds; Dave Murfin; James Daniels; Russell Martin; William Flanders; Dave Vander Griend; Eric Mork; Paul Cantrell

    2010-03-07

    A pilot carbon dioxide miscible flood was initiated in the Lansing Kansas City C formation in the Hall Gurney Field, Russell County, Kansas. The reservoir zone is an oomoldic carbonate located at a depth of about 2900 feet. The pilot consists of one carbon dioxide injection well and three production wells. Continuous carbon dioxide injection began on December 2, 2003. By the end of June 2005, 16.19 MM lb of carbon dioxide was injected into the pilot area. Injection was converted to water on June 21, 2005 to reduce operating costs to a breakeven level with the expectation that sufficient carbon dioxide was injected to displace the oil bank to the production wells by water injection. By March 7,2010, 8,736 bbl of oil were produced from the pilot. Production from wells to the northwest of the pilot region indicates that oil displaced from carbon dioxide injection was produced from Colliver A7, Colliver A3, Colliver A14 and Graham A4 located on adjacent leases. About 19,166 bbl of incremental oil were estimated to have been produced from these wells as of March 7, 2010. There is evidence of a directional permeability trend toward the NW through the pilot region. The majority of the injected carbon dioxide remains in the pilot region, which has been maintained at a pressure at or above the minimum miscibility pressure. Estimated oil recovery attributed to the CO2 flood is 27,902 bbl which is equivalent to a gross CO2 utilization of 4.8 MCF/bbl. The pilot project is not economic.

  2. Effect of sizing on carbon fiber surface properties and fibers/epoxy interfacial adhesion

    International Nuclear Information System (INIS)

    Dai Zhishuang; Shi Fenghui; Zhang Baoyan; Li Min; Zhang Zuoguang

    2011-01-01

    This paper aims to study effect of sizing on surface properties of carbon fiber and the fiber/epoxy interfacial adhesion by comparing sized and desized T300B and T700SC carbon fibers. By means of X-ray photoelectron spectroscopy (XPS), activated carbon atoms can be detected, which are defined as the carbon atoms conjunction with oxygen and nitrogen. Surface chemistry analysis shows that the desized carbon fibers present less concentration of activated carbon, especially those connect with the hydroxyl and epoxy groups. Inverse gas chromatography (IGC) analysis reveals that the desized carbon fibers have larger dispersive surface energy γ S D and smaller polar component γ S SP than the commercial sized ones. Moreover, micro-droplet test shows that the interfacial shear strength (IFSS) of the desized carbon fiber/epoxy is higher than those of the T300B and T700SC. Variations of the IFSS for both the sized and desized carbon fibers correspond to γ S D /γ S tendency of the fiber surface, however the work of adhesion does not reveal close correlation with IFSS trend for different fiber/epoxy systems.

  3. Surface modification of polyacrylonitrile-based carbon fiber and its interaction with imide

    International Nuclear Information System (INIS)

    Xu Bing; Wang Xiaoshu; Lu Yun

    2006-01-01

    In this work, sized polyacrylonitrile (PAN)-based carbon fibers were chemically modified with nitric acid and maleic anhydride (MA) in order to improve the interaction between carbon fiber surface and polyimide matrix. Bismaleimide (BMI) was selected as a model compound of polyimide to react with modified carbon fiber. The surface characteristic changing after modification and surface reaction was investigated by element analysis (EA), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and surface enhanced Raman scattering (SERS). The results indicated that the modification of carbon fiber surface with MA might follow the Diels Alder reaction mechanism. In the surface reaction between modified fibers and BMI, among the various surface functional groups, the hydroxyl group provided from phenolic hydroxyl group and bridged structure on carbon fiber may be the most effective group reacted with imide structure. The results may shed some light on the design of the appropriate surface structure, which could react with polyimide, and the manufacture of the carbon fiber-reinforced polyimide matrix composites

  4. Manganese(III) Formate: A Three-Dimensional Framework That Traps Carbon Dioxide Molecules.

    Science.gov (United States)

    Cornia, Andrea; Caneschi, Andrea; Dapporto, Paolo; Fabretti, Antonio C; Gatteschi, Dante; Malavasi, Wanda; Sangregorio, Claudio; Sessoli, Roberta

    1999-06-14

    Carbon dioxide, formic acid, and water molecules are trapped in the crystal lattice of manganese(III) formate (see 1), which was obtained by reducing permanganate with formic acid. Each CO 2 guest molecule exhibits four C-H⋅⋅⋅O-C-O interactions with the three-dimensional host framework of Mn(HCOO) 3 units. Compound 1 undergoes an antiferromagnetic phase transition at 27 K. © 1999 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

  5. Formation of the minor phase shell on the surface of hypermonotectic alloy powders

    International Nuclear Information System (INIS)

    Zhao, J.Z.

    2006-01-01

    The microstructure evolution in an atomized hypermonotectic alloy drop is calculated. The results indicate that the formation of the minor phase shell on the surface of the powder is due to the heterogeneous nucleation of the minor phase droplets on the atomized drop surface and the resultant diffusional transfer of solute during the liquid-liquid phase transformation

  6. Numerical study on formation process of helical nonneutral plasmas using electron injection from outside magnetic surfaces

    International Nuclear Information System (INIS)

    Nakamura, Kazutaka; Himura, Haruhiko; Masamune, Sadao; Sanpei, Akio; Isobe, Mitsutaka

    2009-01-01

    In order to investigate the formation process of helical nonneutral plasmas, we calculate the orbits of electron injected in the stochastic magnetic field when the closed helical magnetic surfaces is correspond with the equipotential surfaces. Contrary to the experimental observation, there are no electrons inward penetrating. (author)

  7. Evidence for microbial activity in the formation of carbonate-hosted Zn-Pb deposits

    Science.gov (United States)

    Kucha, H.; Raith, J.

    2009-04-01

    *Kucha H **Raith J *University of Mining and Metallurgy, Faculty of Geology, Geophysics and Environmental Protection, Mickiewicza 30, PL-30-059 Krakow, Poland. ** University of Leoben, Department of Applied Geosciences and Geophysics, A-8700 Leoben, Peter Tunner Str. 5, Austria Evidence for microbial activity in the formation of carbonate-hosted Zn-Pb deposits To date evaluation of bacterial processes in the formation of carbonate-hosted Zn-Pb deposits is largely based on sulphur isotope evidence. However, during a past few years, textural criteria, have been established, which support the bacterial origin of many of these deposits. This has received a strong support from micro-, and nano-textures of naturally growing bacterial films in a flooded tunnel within carbonates that host the Piquette Zn-Pb deposit (Druschel et al., 2002). Bacterial textures, micro- and nano textures found in carbonate-hosted Zn-Pb deposits are: i)wavy bacterial films up to a few mm thick to up to a few cm long composed of peloids, ii)semimassive agglomeration of peloids in the carbonate matrix, and iii)solitary peloids dispersed in the carbonate matrix. Peloids are usually composed of a distinct 50-90um core most often made up of Zn-bearing calcite surrounded by 30-60um thick dentate rim composed of ZnS. Etching of Zn-carbonate cores reveals 1 - 2um ZnS filaments, and numerous 15 to 90nm large ZnS nano-spheres (Kucha et al., 2005). In massive ore composite Zn-calcite - sphalerite peloids are entirely replaced by zinc sulphide, and form peloids ghosts within banded sulphide layers. Bacterially derived micro- and nano-textures have been observed in the following carbonate-hosted Zn-Pb deposits: 1)Irish-type Zn-Pb deposits. In the Navan deposit the basic sulphur is isotopically light bacteriogenic S (Fallick at al., 2001). This is corroborated by semimassive agglomerations of composite peloids (Zn-calcite-ZnS corona or ZnS core-melnikovite corona). Etching of Zn-calcite core reveals globular

  8. Biofilm Formation of Staphylococcus aureus on Various Surfaces and Their Resistance to Chlorine Sanitizer.

    Science.gov (United States)

    Lee, Jung-Su; Bae, Young-Min; Lee, Sook-Young; Lee, Sun-Young

    2015-10-01

    This study investigated the effect of material types (polystyrene, polypropylene, glass, and stainless steel) and glucose addition on Staphylococcus aureus biofilm formation, and the relationship between biofilm formation measured by crystal violet (CV) staining and the number of biofilm cells determined by cell counts was studied. We also evaluated the efficacy of chlorine sanitizer on inhibiting various different types of S. aureus biofilms on the surface of stainless steel. Levels of biofilm formation of S. aureus were higher on hydrophilic surfaces (glass and stainless steel) than on hydrophobic surfaces (polypropylene and polystyrene). With the exception of biofilm formed on glass, the addition of glucose in broth significantly increased the biofilm formation of S. aureus on all surfaces and for all tested strains (P ≤ 0.05). The number of biofilm cells was not correlated with the biomass of the biofilms determined using the CV staining method. The efficacy of chlorine sanitizer against biofilm of S. aureus was not significantly different depending on types of biofilm (P > 0.05). Therefore, further studies are needed in order to determine an accurate method quantifying levels of bacterial biofilm and to evaluate the resistance of bacterial biofilm on the material surface. Biofilm formation of Staphylococcus aureus on the surface was different depending on the surface characteristics and S. aureus strains. There was low correlation between crystal violet staining method and viable counts technique for measuring levels of biofilm formation of S. aureus on the surfaces. These results could provide helpful information for finding and understanding the quantification method and resistance of bacterial biofilm on the surface. © 2015 Institute of Food Technologists®

  9. CARBON DIOXIDE INFLUENCE ON THE THERMAL FORMATION OF COMPLEX ORGANIC MOLECULES IN INTERSTELLAR ICE ANALOGS

    Energy Technology Data Exchange (ETDEWEB)

    Vinogradoff, V.; Fray, N.; Bouilloud, M.; Cottin, H. [LISA Laboratoire Interuniversitaire des Systèmes Atmosphériques, UMR CNRS 7583, Université Paris Est Créteil (UPEC), Université Paris Diderot (UPD), Institut Pierre Simon Laplace, Labex ESEP, Paris (France); Duvernay, F.; Chiavassa, T., E-mail: vvinogradoff@mnhn.fr [PIIM, Laboratoire de Physique des Interactions Ioniques et Moléculaires, Université Aix-Marseille, UMR CNRS 7345, Marseille (France)

    2015-08-20

    Interstellar ices are submitted to energetic processes (thermal, UV, and cosmic-ray radiations) producing complex organic molecules. Laboratory experiments aim to reproduce the evolution of interstellar ices to better understand the chemical changes leading to the reaction, formation, and desorption of molecules. In this context, the thermal evolution of an interstellar ice analogue composed of water, carbon dioxide, ammonia, and formaldehyde is investigated. The ice evolution during the warming has been monitored by IR spectroscopy. The formation of hexamethylenetetramine (HMT) and polymethylenimine (PMI) are observed in the organic refractory residue left after ice sublimation. A better understanding of this result is realized with the study of another ice mixture containing methylenimine (a precursor of HMT) with carbon dioxide and ammonia. It appears that carbamic acid, a reaction product of carbon dioxide and ammonia, plays the role of catalyst, allowing the reactions toward HMT and PMI formation. This is the first time that such complex organic molecules (HMT, PMI) are produced from the warming (without VUV photolysis or irradiation with energetic particles) of abundant molecules observed in interstellar ices (H{sub 2}O, NH{sub 3}, CO{sub 2}, H{sub 2}CO). This result strengthens the importance of thermal reactions in the ices’ evolution. HMT and PMI, likely components of interstellar ices, should be searched for in the pristine objects of our solar system, such as comets and carbonaceous chondrites.

  10. CARBON DIOXIDE INFLUENCE ON THE THERMAL FORMATION OF COMPLEX ORGANIC MOLECULES IN INTERSTELLAR ICE ANALOGS

    International Nuclear Information System (INIS)

    Vinogradoff, V.; Fray, N.; Bouilloud, M.; Cottin, H.; Duvernay, F.; Chiavassa, T.

    2015-01-01

    Interstellar ices are submitted to energetic processes (thermal, UV, and cosmic-ray radiations) producing complex organic molecules. Laboratory experiments aim to reproduce the evolution of interstellar ices to better understand the chemical changes leading to the reaction, formation, and desorption of molecules. In this context, the thermal evolution of an interstellar ice analogue composed of water, carbon dioxide, ammonia, and formaldehyde is investigated. The ice evolution during the warming has been monitored by IR spectroscopy. The formation of hexamethylenetetramine (HMT) and polymethylenimine (PMI) are observed in the organic refractory residue left after ice sublimation. A better understanding of this result is realized with the study of another ice mixture containing methylenimine (a precursor of HMT) with carbon dioxide and ammonia. It appears that carbamic acid, a reaction product of carbon dioxide and ammonia, plays the role of catalyst, allowing the reactions toward HMT and PMI formation. This is the first time that such complex organic molecules (HMT, PMI) are produced from the warming (without VUV photolysis or irradiation with energetic particles) of abundant molecules observed in interstellar ices (H 2 O, NH 3 , CO 2 , H 2 CO). This result strengthens the importance of thermal reactions in the ices’ evolution. HMT and PMI, likely components of interstellar ices, should be searched for in the pristine objects of our solar system, such as comets and carbonaceous chondrites

  11. Formation of nanostructures on HOPG surface in presence of surfactant atom during low energy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ranjan, M., E-mail: ranjanm@ipr.res.in; Joshi, P.; Mukherjee, S.

    2016-07-15

    Low energy ions beam often develop periodic patterns on surfaces under normal or off-normal incidence. Formation of such periodic patterns depends on the substrate material, the ion beam parameters, and the processing conditions. Processing conditions introduce unwanted contaminant atoms, which also play strong role in pattern formation by changing the effective sputtering yield of the material. In this work we have analysed the effect of Cu, Fe and Al impurities introduced during low energy Ar{sup +} ion irradiation on HOPG substrate. It is observed that by changing the species of foreign atoms the surface topography changes drastically. The observed surface topography is co-related with the modified sputtering yield of HOPG. Presence of Cu and Fe amplify the effective sputtering yield of HOPG, so that the required threshold for the pattern formation is achieved with the given fluence, whereas Al does not lead to any significant change in the effective yield and hence no pattern formation occurs.

  12. Effects of surface properties on droplet formation inside a microfluidic device

    Science.gov (United States)

    Steinhaus, Ben; Shen, Amy

    2004-11-01

    Micro-fluidic devices offer a unique method of creating and controlling droplets on small length scales. A microfluidic device is used to study the effects of surface properties on droplet formation of a 2-phase flow system. Four phase diagrams are generated to compare the dynamics of the 2 immiscible fluid system (silicone oil and water) inside microchannels with different surface properties. Results show that the channel surface plays an important role in determining the flow patterns and the droplet formation of the 2-phase fluid system.

  13. Surface relief grating formation on a single crystal of 4-(dimethylamino)azobenzene

    International Nuclear Information System (INIS)

    Nakano, Hideyuki; Tanino, Takahiro; Shirota, Yasuhiko

    2005-01-01

    Surface relief grating (SRG) formation on an organic single crystal by irradiation with two coherent laser beams has been demonstrated by using 4-(dimethylamino)azobenzene (DAAB). It was found that the SRG formation was greatly depending upon both the coordination of the crystal and the polarization of the writing beams. The dependence of the polarization of writing beams on the SRG formation using the single crystal was found to be quite different from that reported for amorphous polymers and photochromic amorphous molecular materials, suggesting that the mechanism of the SRG formation on the organic crystal is somewhat different from that on amorphous materials

  14. Formation of Nanostructures on the Nickel Metal Surface in Ionic Liquid under Anodizing

    Science.gov (United States)

    Lebedeva, O. K.; Root, N. V.; Kultin, D. Yu.; Kalmykov, K. B.; Kustov, L. M.

    2018-05-01

    The formation of nanostructures in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide on the surface of a nickel electrode during anodizing was studied. Hexagonal ordered surface nanostructures were found to form in a narrow range of current densities. The form of the potential transients of the nickel electrode corresponded to the morphology of the nickel surface obtained which was studied by electron microscopy. No other types of nanostructures were found under the electrosynthesis conditions under study.

  15. Spent coffee-based activated carbon: specific surface features and their importance for H2S separation process.

    Science.gov (United States)

    Kante, Karifala; Nieto-Delgado, Cesar; Rangel-Mendez, J Rene; Bandosz, Teresa J

    2012-01-30

    Activated carbons were prepared from spent ground coffee. Zinc chloride was used as an activation agent. The obtained materials were used as a media for separation of hydrogen sulfide from air at ambient conditions. The materials were characterized using adsorption of nitrogen, elemental analysis, SEM, FTIR, and thermal analysis. Surface features of the carbons depend on the amount of an activation agent used. Even though the residual inorganic matter takes part in the H(2)S retention via salt formation, the porous surface of carbons governs the separation process. The chemical activation method chosen resulted in formation of large volume of pores with sizes between 10 and 30Å, optimal for water and hydrogen sulfide adsorption. Even though the activation process can be optimized/changed, the presence of nitrogen in the precursor (caffeine) is a significant asset of that specific organic waste. Nitrogen functional groups play a catalytic role in hydrogen sulfide oxidation. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Surface modification, characterization and adsorptive properties of a coconut activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Lu Xincheng [Institute of Chemical Industry of Forest Products, CAF, National Engineering Lab. for Biomass Chemical Utilization, Key and Open Lab. of Forest Chemical Engineering, SFA, Key Lab. of Biomass Energy and Material, Jiangsu Province, Suojin wucun 16, Nanjing 210042 (China); Jiang Jianchun, E-mail: lhs_ac2011@yahoo.cn [Institute of Chemical Industry of Forest Products, CAF, National Engineering Lab. for Biomass Chemical Utilization, Key and Open Lab. of Forest Chemical Engineering, SFA, Key Lab. of Biomass Energy and Material, Jiangsu Province, Suojin wucun 16, Nanjing 210042 (China); Sun Kang; Xie Xinping; Hu Yiming [Institute of Chemical Industry of Forest Products, CAF, National Engineering Lab. for Biomass Chemical Utilization, Key and Open Lab. of Forest Chemical Engineering, SFA, Key Lab. of Biomass Energy and Material, Jiangsu Province, Suojin wucun 16, Nanjing 210042 (China)

    2012-08-01

    A coconut activated carbon was modified using chemical methods. Different concentration of nitric acid oxidation of the conventional sample produced samples with weakly acidic functional groups. The oxidized samples were characterized by scanning electron micrograph, nitrogen absorption-desorption, Fourier transform infra red spectroscopy, Bothem method, pH titration, adsorption capacity of sodium and formaldehyde, and the adsorption mechanism of activated carbons was investigated. The results showed that BET surface area and pore volume of activated carbons were decreased after oxidization process, while acidic functional groups were increased. The surface morphology of oxidized carbons looked clean and eroded which was caused by oxidization of nitric acid. The oxidized carbons showed high adsorption capacity of sodium and formaldehyde, and chemical properties of activated carbon played an important role in adsorption of metal ions and organic pollutants.

  17. Influence of surface finish on the plasma formation at the skin explosion

    International Nuclear Information System (INIS)

    Datsko, I M; Chaikovsky, S A; Labetskaya, N A; Rybka, D V; Oreshkin, V I; Khishchenko, K V

    2016-01-01

    The paper reports on experiments to investigate how the quality of surface finish, i.e., surface roughness, influences the plasma formation in a skin explosion of conductors. The experiments were performed on a MIG terawatt generator with a current amplitude of up to 2.5 MA and current rise time of 100 ns. The plasma formation at the conductor surface and the evolution of the plasma boundary was recorded using a four-frame optical camera with an exposure time of 3 ns per frame. It is shown that the quality of surface finish little affects the onset of plasma formation in a skin explosion of stainless steel and St3 steel conductors at a magnetic field of up to 400 T. (paper)

  18. Tuning the Wettability of Halloysite Clay Nanotubes by Surface Carbonization for Optimal Emulsion Stabilization.

    Science.gov (United States)

    Owoseni, Olasehinde; Zhang, Yueheng; Su, Yang; He, Jibao; McPherson, Gary L; Bose, Arijit; John, Vijay T

    2015-12-29

    The carbonization of hydrophilic particle surfaces provides an effective route for tuning particle wettability in the preparation of particle-stabilized emulsions. The wettability of naturally occurring halloysite clay nanotubes (HNT) is successfully tuned by the selective carbonization of the negatively charged external HNT surface. The positively charge chitosan biopolymer binds to the negatively charged external HNT surface by electrostatic attraction and hydrogen bonding, yielding carbonized halloysite nanotubes (CHNT) on pyrolysis in an inert atmosphere. Relative to the native HNT, the oil emulsification ability of the CHNT at intermediate levels of carbonization is significantly enhanced due to the thermodynamically more favorable attachment of the particles at the oil-water interface. Cryogenic scanning electron microscopy (cryo-SEM) imaging reveals that networks of CHNT attach to the oil-water interface with the particles in a side-on orientation. The concepts advanced here can be extended to other inorganic solids and carbon sources for the optimal design of particle-stabilized emulsions.

  19. Kinetic of formation for single carbon dioxide and mixed carbon dioxide and tetrahydrofuran hydrates in water and sodium chloride aqueous solution

    NARCIS (Netherlands)

    Sabil, K.M.; Duarte, A.R.C.; Zevenbergen, J.F.; Ahmad, M.M.; Yusup, S.; Omar, A.A.; Peters, C.J.

    2010-01-01

    A laboratory-scale reactor system is built and operated to measure the kinetic of formation for single and mixed carbon dioxide-tetrahydrofuran hydrates. The T-cycle method, which is used to collect the kinetic data, is briefly discussed. For single carbon dioxide hydrate, the induction time

  20. Improving the corrosion resistance of proton exchange membrane fuel cell carbon supports by pentafluorophenyl surface functionalization

    Science.gov (United States)

    Forouzandeh, Farisa; Li, Xiaoan; Banham, Dustin W.; Feng, Fangxia; Joseph Kakanat, Abraham; Ye, Siyu; Birss, Viola

    2018-02-01

    In this study, the effect of surface functionalization on the electrochemical corrosion resistance of a high surface area, mesoporous colloid imprinted carbon powder (CIC), as well as microporous Vulcan carbon (VC, serving as the benchmark), was demonstrated, primarily for PEM fuel cell applications. CIC-22, which is highly hydrophilic and was synthesized with 22 nm silica colloid templates, and as-received, mildly hydrophobic, VC powders, were functionalized with 2,3,4,5,6-pentafluorophenyl (-PhF5) surface groups using a straightforward diazonium reduction reaction. These carbons were then subjected to corrosion testing, involving a potential cycling-step sequence in room temperature 0.5 M H2SO4. Using cyclic voltammetry and charge/time analysis, the double layer and pseudo-capacitive gravimetric charges of the carbons, prior to and after the application of these potential steps, were tracked in order to obtain information about surface area changes and the extent of carbon oxidation, respectively. It is shown that the corrosion resistance was improved by ca. 50-80% by surface functionalization, likely due to a combination of surface passivation (loss of carbon active sites) and increased surface hydrophobicity.

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

    Science.gov (United States)

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

    2013-06-17

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

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

    Science.gov (United States)

    2013-01-01

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

  3. Tailoring surface groups of carbon quantum dots to improve photoluminescence behaviors

    International Nuclear Information System (INIS)

    Tian, Ruixue; Hu, Shengliang; Wu, Lingling; Chang, Qing; Yang, Jinlong; Liu, Jun

    2014-01-01

    Highlights: • We develop a facile and green method to tailor surface groups. • Photoluminescence behaviors of carbon quantum dots are improved by tailoring their surface groups. • Highly luminescent efficiency is produced by amino-hydrothermal treatment of reduced carbon quantum dots. - Abstract: A facile and green method to tailor surface groups of carbon quantum dots (CQDs) is developed by hydrothermal treatment in an autoclave. The photoluminescence (PL) behaviors of CQDs depend on the types of surface groups. Highly efficient photoluminescence is obtained through amino-hydrothermal treatment of the CQDs reduced by NaBH 4 . The effects of surface groups on PL behavior are attributed to the degrees of energy band bending induced by surface groups

  4. Influence of cation size and surface coverage upon the infrared spectrum of carbon monoxide

    OpenAIRE

    Huang, Jimin

    1991-01-01

    Adsorbed carbon monoxide is utilized as a double layer probe molecule because of its strong absorption in infrared region and because of the high sensitivity of the carbon-oxygen bond to changes in the environment local to the electrode surface. Potential Difference Infrared Spectroscopy was used to investigate the structural behavior of CO adsorbed on a platinum electrode. Carbon monoxide was found to be exclusively linear-bonded on platinum electrode in the presence of tetran...

  5. Carbon 13 and oxygen 18 isotope record of the early eocene nammal formation, salt range, pakistan

    International Nuclear Information System (INIS)

    Ghazi, S.; Sajid, Z.

    2014-01-01

    The Nammal Formation is the lowermost unit of the Early Eocene succession in the Salt Range, Pakistan. It is well exposed throughout the Salt Range. The Nammal Formation having 30 to 35 meters thickness is predominantly composed of nodular limestone interbedded with marl and shale. The present study was focussed on stable carbon 13 and oxygen 18 isotopic analysis based on data from two stratigraphically important sections. The samples from the Nilawahan section provided with the delta 13C values varied between 1.34 to -1.56 (VPDB) and values of delta 18O fluctuated between -4.47 to -6.59 (VPDB). Likewise the sample analysis of BadshahPur section exhibited that the delta 13C values changes from 1.09 to -1.65 (VPDB) and delta 18O values range from -4.17 to -6.85 (VPDB). The isotopic records of carbon 13 and oxygen 18 indicated the shallow marine deposition of the Nammal Formation under tropical conditions. It highlighted the palaeo climatic and diagenetic conditions of the Nammal Formation at the time of deposition in the Salt Range region. (author)

  6. Surface oxide formation during corona discharge treatment of AA 1050 aluminium surfaces

    DEFF Research Database (Denmark)

    Minzari, Daniel; Møller, Per; Kingshott, Peter

    2008-01-01

    process modifies aluminium AA 1050 surface, the oxide growth and resulting corrosion properties. The corona treatment is carried out in atmospheric air. Treated surfaces are characterized using XPS, SEM/EDS, and FIB-FESEM and results suggest that an oxide layer is grown, consisting of mixture of oxide...

  7. Optimized preparation for large surface area activated carbon from date (Phoenix dactylifera L.) stone biomass

    International Nuclear Information System (INIS)

    Danish, Mohammed; Hashim, Rokiah; Ibrahim, M.N. Mohamad; Sulaiman, Othman

    2014-01-01

    The preparation of activated carbon from date stone treated with phosphoric acid was optimized using rotatable central composite design of response surface methodology (RSM). The chemical activating agent concentration and temperature of activation plays a crucial role in preparation of large surface area activated carbons. The optimized activated carbon was characterized using thermogravimetric analysis, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, powder X-ray diffraction, and Fourier transform infrared spectroscopy. The results showed that the larger surface area of activated carbon from date stone can be achieved under optimum activating agent (phosphoric acid) concentration, 50.0% (8.674 mol L −1 ) and activation temperature, 900 °C. The Brunauer–Emmett–Teller (BET) surface area of optimized activated carbon was found to be 1225 m 2  g −1 , and thermogravimetric analysis revealed that 55.2% mass of optimized activated carbon was found thermally stable till 900 °C. The leading chemical functional groups found in the date stone activated carbon were aliphatic carboxylic acid salt ν(C=O) 1561.22 cm −1 and 1384.52 cm −1 , aliphatic hydrocarbons ν(C–H) 2922.99 cm −1 (C–H sym./asym. stretch frequency), aliphatic phosphates ν(P–O–C) 1054.09 cm −1 , and secondary aliphatic alcohols ν(O–H) 3419.81 cm −1 and 1159.83 cm −1 . - Highlights: • RSM optimization was done for the production of large surface area activated carbon. • Two independent variables with two responses were selected for optimization. • Characterization was done for surface area, morphology and chemical constituents. • Optimized date stone activated carbon achieved surface area 1225 m 2  g −1

  8. The surface interactions of a near-neutral carbon nanoparticle tracer with calcite

    KAUST Repository

    Li, Yan Vivian; Cathles, Lawrence M.

    2016-01-01

    A new class of nearly charge-neutral carbon-cored nanoparticle tracers are remarkably non-interactive with solid surfaces and could provide a valuable baseline for diverse hydrological and environmental studies of subsurface flow and particle

  9. Estimation of Carbon Sink in Surface Carbonate Rocks of Guangxi Province by Using Remote Sensing Images

    Science.gov (United States)

    Jia, B.; Zhou, G.; Wang, H.; Yue, T.; Huang, W.

    2018-04-01

    Studies of the imbalance of source sinks in the carbon cycle show that CO2 absorbed during rock weathering is part of the "miss carbon" of the global carbon cycle. The carbon sink contribution of carbonate rocks obviously plays a very important role in the absorption of atmospheric CO2. Estimation of carbon sinks in karst dynamic system of Guangxi province has great significance for further understanding of global karst carbon cycle and global climate research. This paper quotes the rock data from Tao Xiaodong's paper, which is obtained using RS and GIS techniques. At the same time, the dissolution rate model studied by Zhou Guoqing and others was used to estimate the dissolution rate of carbonate rocks in Guangxi Province. Finally, the CO2 content consumed by carbonate karstification in Guangxi Province was 1342910.447 t a-1. The results obtained are in the same order of magnitude as the CO2 content consumed by carbonate rock karstification in Guangxi Province calculated by Tao Xiaodong.

  10. THE EFFECT OF ACTIVATED CARBON SURFACE MOISTURE ON LOW TEMPERATURE MERCURY ADSORPTION

    Science.gov (United States)

    Experiments with elemental mercury (Hg0) adsorption by activated carbons were performed using a bench-scale fixed-bed reactor at room temperature (27 degrees C) to determine the role of surface moisture in capturing Hg0. A bituminous-coal-based activated carbon (BPL) and an activ...

  11. Crystal size effect on the electrochemical oxidation of formate on carbon-supported palladium nanoparticles

    International Nuclear Information System (INIS)

    Santos, Rayana Marcela Izidoro da Silva; Nakazato, Roberto Zenhei; Ciapina, Eduardo Goncalves

    2016-01-01

    Full text: The electrochemical oxidation of formate in alkaline electrolytes has emerged an a promising anodic reaction in the Direct Formate Fuel Cells[1]. Although palladium is considered to be one of the best electro catalyst for the oxidation of formate, important structure-activity relationships are still not understood. In the present work, we investigated the effect of the size of the palladium crystals in the electrochemical oxidation of formate in 0.1 mol L -1 KOH. Carbon-supported palladium nanoparticles (Pd/C) were prepared by chemical reduction of palladium (II) chloride in aqueous media by sodium borohydride in the presence of varying quantities of sodium citrate in the reaction media to obtain metallic crystals with distinct sizes. Analysis of the X-ray diffraction profile revealed the presence of palladium crystals in the range of 6 to 19 nm. Potentiostatic oxidation of formate on the distinct Pd/C samples revealed a volcano-like dependence of the specific activity with the size of the palladium crystals, presenting the highest activity for crystals around 7.5 nm. Reference: [1] A.M. Bartrom, J.L. Haan, The direct formate fuel cell with an alkaline anion exchange membrane, J. Power Sources. 214 (2012) 68-74. (author)

  12. Leakage and Seepage of CO2 from Geologic Carbon Sequestration Sites: CO2 Migration into Surface Water

    International Nuclear Information System (INIS)

    Oldenburg, Curt M.; Lewicki, Jennifer L.

    2005-01-01

    Geologic carbon sequestration is the capture of anthropogenic carbon dioxide (CO 2 ) and its storage in deep geologic formations. One of the concerns of geologic carbon sequestration is that injected CO 2 may leak out of the intended storage formation, migrate to the near-surface environment, and seep out of the ground or into surface water. In this research, we investigate the process of CO 2 leakage and seepage into saturated sediments and overlying surface water bodies such as rivers, lakes, wetlands, and continental shelf marine environments. Natural CO 2 and CH 4 fluxes are well studied and provide insight into the expected transport mechanisms and fate of seepage fluxes of similar magnitude. Also, natural CO 2 and CH 4 fluxes are pervasive in surface water environments at levels that may mask low-level carbon sequestration leakage and seepage. Extreme examples are the well known volcanic lakes in Cameroon where lake water supersaturated with respect to CO 2 overturned and degassed with lethal effects. Standard bubble formation and hydrostatics are applicable to CO 2 bubbles in surface water. Bubble-rise velocity in surface water is a function of bubble size and reaches a maximum of approximately 30 cm s -1 at a bubble radius of 0.7 mm. Bubble rise in saturated porous media below surface water is affected by surface tension and buoyancy forces, along with the solid matrix pore structure. For medium and fine grain sizes, surface tension forces dominate and gas transport tends to occur as channel flow rather than bubble flow. For coarse porous media such as gravels and coarse sand, buoyancy dominates and the maximum bubble rise velocity is predicted to be approximately 18 cm s -1 . Liquid CO 2 bubbles rise slower in water than gaseous CO 2 bubbles due to the smaller density contrast. A comparison of ebullition (i.e., bubble formation) and resulting bubble flow versus dispersive gas transport for CO 2 and CH 4 at three different seepage rates reveals that

  13. Surface-Enhanced Raman Spectroscopy of Carbon Nanomembranes from Aromatic Self-Assembled Monolayers.

    Science.gov (United States)

    Zhang, Xianghui; Mainka, Marcel; Paneff, Florian; Hachmeister, Henning; Beyer, André; Gölzhäuser, Armin; Huser, Thomas

    2018-02-27

    Surface-enhanced Raman scattering spectroscopy (SERS) was employed to investigate the formation of self-assembled monolayers (SAMs) of biphenylthiol, 4'-nitro-1,1'-biphenyl-4-thiol, and p-terphenylthiol on Au surfaces and their structural transformations into carbon nanomembranes (CNMs) induced by electron irradiation. The high sensitivity of SERS allows us to identify two types of Raman scattering in electron-irradiated SAMs: (1) Raman-active sites exhibit similar bands as those of pristine SAMs in the fingerprint spectral region, but with indications of an amorphization process and (2) Raman-inactive sites show almost no Raman-scattering signals, except a very weak and broad D band, indicating a lack of structural order but for the presence of graphitic domains. Statistical analysis showed that the ratio of the number of Raman-active sites to the total number of measurement sites decreases exponentially with increasing the electron irradiation dose. The maximum degree of cross-linking ranged from 97 to 99% for the three SAMs. Proof-of-concept experiments were conducted to demonstrate potential applications of Raman-inactive CNMs as a supporting membrane for Raman analysis.

  14. Boron ion irradiation induced structural and surface modification of glassy carbon

    International Nuclear Information System (INIS)

    Kalijadis, Ana; Jovanović, Zoran; Cvijović-Alagić, Ivana; Laušević, Zoran

    2013-01-01

    The incorporation of boron into glassy carbon was achieved by irradiating two different types of targets: glassy carbon polymer precursor and carbonized glassy carbon. Targets were irradiated with a 45 keV B 3+ ion beam in the fluence range of 5 × 10 15 –5 × 10 16 ions cm −2 . For both types of targets, the implanted boron was located in a narrow region under the surface. Following irradiation, the polymer was carbonized under the same condition as the glassy carbon samples (at 1273 K) and examined by Raman spectroscopy, temperature programmed desorption, hardness and cyclic voltammetry measurements. Structural analysis showed that during the carbonization process of the irradiated polymers, boron is substitutionally incorporated into the glassy carbon structure, while for irradiated carbonized glassy carbon samples, boron irradiation caused an increase of the sp 3 carbon fraction, which is most pronounced for the highest fluence irradiation. Further analyses showed that different nature of boron incorporation, and thus changed structural parameters, are crucial for obtaining glassy carbon samples with modified mechanical, chemical and electrochemical properties over a wide range

  15. Emerging surface characterization techniques for carbon steel corrosion: a critical brief review

    OpenAIRE

    Dwivedi, D.; Lepkova, K.; Becker, T.

    2017-01-01

    Carbon steel is a preferred construction material in many industrial and domestic applications, including oil and gas pipelines, where corrosion mitigation using film-forming corrosion inhibitor formulations is a widely accepted method. This review identifies surface analytical techniques that are considered suitable for analysis of thin films at metallic substrates, but are yet to be applied to analysis of carbon steel surfaces in corrosive media or treated with corrosion inhibitors. The rev...

  16. Effect of ion irradiation on the structure and the surface topography of carbon fiber

    International Nuclear Information System (INIS)

    Ligacheva, E.A.; Galyaeva, L.V.; Gavrilov, N.V.; Belykh, T.A.; Ligachev, A.E.; Sokhoreva, V.V.

    2006-01-01

    The effect of C + ion irradiation (40 keV, 10 15 - 10 19 cm -2 ) on the structure and surface topography of high-module carbon fibers is investigated. Interplanar distance and internal stress values are found to be minimal at a radiation dose of 10 17 cm -2 , the height of a layer pack being practically unchanged. The relief of ion irradiated carbon fiber surface constitutes regularly repetitive valleys and ridges spaced parallel with the fiber axis [ru

  17. Biofilm formation by Listeria monocytogenes on stainless steel surface and biotransfer potential

    Directory of Open Access Journals (Sweden)

    Maíra Maciel Mattos de Oliveira

    2010-03-01

    Full Text Available An experimental model was proposed to study biofilm formation by Listeria monocytogenes ATCC 19117 on AISI 304 (#4 stainless steel surface and biotransfer potential during this process. In this model, biofilm formation was conducted on the surface of stainless steel coupons, set on a stainless steel base with 4 divisions, each one supporting 21 coupons. Trypic Soy Broth was used as bacterial growth substrate, with incubation at 37 ºC and stirring of 50 rpm. The number of adhered cells was determined after 3, 48, 96, 144, 192 and 240 hours of biofilm formation and biotransfer potential from 96 hours. Stainless steel coupons were submitted to Scanning Electron Microscopy (SEM after 3, 144 and 240 hours. Based on the number of adhered cells and SEM, it was observed that L. monocytogenes adhered rapidly to the stainless steel surface, with mature biofilm being formed after 240 hours. The biotransfer potential of bacterium to substrate occurred at all the stages analyzed. The rapid capacity of adhesion to surface, combined with biotransfer potential throughout the biofilm formation stages, make L. monocytogenes a potential risk to the food industry. Both the experimental model developed and the methodology used were efficient in the study of biofilm formation by L. monocytogenes on stainless steel surface and biotransfer potential.

  18. Biofilm formation by Listeria monocytogenes on stainless steel surface and biotransfer potential.

    Science.gov (United States)

    de Oliveira, Maíra Maciel Mattos; Brugnera, Danilo Florisvaldo; Alves, Eduardo; Piccoli, Roberta Hilsdorf

    2010-01-01

    An experimental model was proposed to study biofilm formation by Listeria monocytogenes ATCC 19117 on AISI 304 (#4) stainless steel surface and biotransfer potential during this process. In this model, biofilm formation was conducted on the surface of stainless steel coupons, set on a stainless steel base with 4 divisions, each one supporting 21 coupons. Trypic Soy Broth was used as bacterial growth substrate, with incubation at 37 °C and stirring of 50 rpm. The number of adhered cells was determined after 3, 48, 96, 144, 192 and 240 hours of biofilm formation and biotransfer potential from 96 hours. Stainless steel coupons were submitted to Scanning Electron Microscopy (SEM) after 3, 144 and 240 hours. Based on the number of adhered cells and SEM, it was observed that L. monocytogenes adhered rapidly to the stainless steel surface, with mature biofilm being formed after 240 hours. The biotransfer potential of bacterium to substrate occurred at all the stages analyzed. The rapid capacity of adhesion to surface, combined with biotransfer potential throughout the biofilm formation stages, make L. monocytogenes a potential risk to the food industry. Both the experimental model developed and the methodology used were efficient in the study of biofilm formation by L. monocytogenes on stainless steel surface and biotransfer potential.

  19. Modelling of crater formation on anode surface by high-current vacuum arcs

    Science.gov (United States)

    Tian, Yunbo; Wang, Zhenxing; Jiang, Yanjun; Ma, Hui; Liu, Zhiyuan; Geng, Yingsan; Wang, Jianhua; Nordlund, Kai; Djurabekova, Flyura

    2016-11-01

    Anode melting and crater formation significantly affect interruption of high-current vacuum arcs. The primary objective of this paper is to theoretically investigate the mechanism of anode surface crater formation, caused by the combined effect of surface heating during the vacuum arc and pressure exerted on the molten surface by ions and electrons from the arc plasma. A model of fluid flow and heat transfer in the arc anode is developed and combined with a magnetohydrodynamics model of the vacuum arc plasma. Crater formation is observed in simulation for a peak arcing current higher than 15 kA on 40 mm diam. Cu electrodes spaced 10 mm apart. The flow of liquid metal starts after 4 or 5 ms of arcing, and the maximum velocities are 0.95 m/s and 1.39 m/s for 20 kA and 25 kA arcs, respectively. This flow redistributes thermal energy, and the maximum temperature of the anode surface does not remain in the center. Moreover, the condition for the liquid droplet formation on the anode surfaces is developed. The solidification process after current zero is also analyzed. The solidification time has been found to be more than 3 ms after 25 kA arcing. The long solidification time and sharp features on crater rims induce Taylor cone formation.

  20. Carbonate petrography, kerogen distribution, and carbon and oxygen isotope variations in an early Proterozoic transition from limestone to iron-formation deposition, Transvaal Supergroup, South Africa

    Science.gov (United States)

    Beukes, N. J.; Klein, C.; Kaufman, A. J.; Hayes, J. M.

    1990-01-01

    The transition zone comprises Campbellrand microbialaminated (replacing "cryptalgalaminate") limestone and shale, with minor dolomite, conformably overlain by the Kuruman Iron Formation of which the basal part is characterized by siderite-rich microbanded iron-formation with minor magnetite and some hematite-containing units. The iron-formation contains subordinate intraclastic and microbialaminated siderite mesobands and was deposited in deeper water than the limestones. The sequence is virtually unaltered with diagenetic mineral assemblages reflecting a temperature interval of about 110 degrees to 170 degrees C and pressures of 2 kbars. Carbonate minerals in the different rock types are represented by primary micritic precipitates (now recrystallized to microsparite), early precompactional sparry cements and concretions, deep burial limpid euhedral sparites, and spar cements precipitated from metamorphic fluids in close contact with diabase sills. Paragenetic pathways of the carbonate minerals are broadly similar in all lithofacies with kerogen intimately associated with them. Kerogen occurs as pigmentation in carbonate crystals, as reworked organic detritus in clastic-textured carbonate units, and as segregations of kerogen pigment around late diagenetic carbonate crystals. Locally kerogen may also be replaced by carbonate spar. Carbon isotope compositions of the carbonate minerals and kerogen are dependent on their mode of occurrence and on the composition of the dominant carbonate species in a specific lithofacies. Integration of sedimentary, petrographic, geochemical, and isotopic results makes it possible to distinguish between depositional, early diagenetic, deep burial, and metamorphic effects on the isotopic compositions of the carbonate minerals and the kerogen in the sequence. Major conclusions are that deep burial thermal decarboxylation led to 13C depletion in euhedral ferroan sparites and 13C enrichment in kerogen (organic carbon). Metamorphic

  1. Surface zwitterionization: Effective method for preventing oral bacterial biofilm formation on hydroxyapatite surfaces

    Science.gov (United States)

    Lee, Myoungjin; Kim, Heejin; Seo, Jiae; Kang, Minji; Kang, Sunah; Jang, Joomyung; Lee, Yan; Seo, Ji-Hun

    2018-01-01

    In this study, we conducted surface zwitterionization of hydroxyapatite (HA) surfaces by immersing them in the zwitterionic polymer solutions to provide anti-bacterial properties to the HA surface. Three different monomers containing various zwitterionic groups, i.e., phosphorylcholine (PC), sulfobetaine (SB), and carboxybetaine (CB), were copolymerized with the methacrylic monomer containing a Ca2+-binding moiety, using the free radical polymerization method. As a control, functionalization of the copolymer containing the Ca2+-binding moiety was synthesized using a hydroxy group. The stable immobilization of the zwitterionic functional groups was confirmed by water contact angle analysis and X-ray photoelectron spectroscopy (XPS) measurement conducted after the sonication process. The zwitterionized HA surface showed significantly decreased protein adsorption, whereas the hydroxyl group-coated HA surface showed limited efficacy. The anti-bacterial adhesion property was confirmed by conducting Streptococcus mutans (S. mutans) adhesion tests for 6 h and 24 h. When furanone C-30, a representative anti-quorum sensing molecule for S. mutans, was used, only a small amount of bacteria adhered after 6 h and the population did not increase after 24 h. In contrast, zwitterionized HA surfaces showed almost no bacterial adhesion after 6 h and the effect was retained for 24 h, resulting in the lowest level of oral bacterial adhesion. These results confirm that surface zwitterionization is a promising method to effectively prevent oral bacterial adhesion on HA-based materials.

  2. Fe(III) mobilisation by carbonate in low temperature environments: Study of the solubility of ferrihydrite in carbonate media and the formation of Fe(III) carbonate complexes

    International Nuclear Information System (INIS)

    Grivé, Mireia; Duro, Lara; Bruno, Jordi

    2014-01-01

    Graphical abstract: - Highlights: • We have determined thermodynamic stabilities of Fe(III)-carbonate species. • We have determined the effect of those species on the solubility of ferrihydrite. • Results. • Highlight the importance of two Fe(III)-carbonate: FeOHCO 3 and Fe(CO 3 ) 3 3− . - Abstract: The linkage between the iron and the carbon cycles is of paramount importance to understand and quantify the effect of increased CO 2 concentrations in natural waters on the mobility of iron and associated trace elements. In this context, we have quantified the thermodynamic stability of mixed Fe(III) hydroxo-carbonate complexes and their effect on the solubility of Fe(III) oxihydroxides. We present the results of carefully performed solubility measurements of 2-line ferrihydrite in the slightly acidic to neutral–alkaline pH ranges (3.8–8.7) under constant pCO 2 varying between (0.982–98.154 kPa) at 25 °C. The outcome of the work indicates the predominance of two Fe(III) hydroxo carbonate complexes FeOHCO 3 and Fe(CO 3 ) 3 3− , with formation constants log * β° 1,1,1 = 10.76 ± 0.38 and log β° 1,0,3 = 24.24 ± 0.42, respectively. The solubility constant for the ferrihydrite used in this study was determined in acid conditions (pH: 1.8–3.2) in the absence of CO 2 and at T = (25 ± 1) °C, as log * K s,0 = 1.19 ± 0.41. The relative stability of the Fe(III)-carbonate complexes in alkaline pH conditions has implications for the solubility of Fe(III) in CO 2 -rich environments and the subsequent mobilisation of associated trace metals that will be explored in subsequent papers

  3. Surface treatment effect on Si (111) substrate for carbon deposition using DC unbalanced magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Aji, A. S., E-mail: aji.ravazes70@gmail.com; Sahdan, M. F.; Hendra, I. B.; Dinari, P.; Darma, Y. [Quantum Semiconductor and Devices Lab., Physics of Material Electronics Research Division, Department of Physics, Institut Teknologi Bandung (Indonesia)

    2015-04-16

    In this work, we studied the effect of HF treatment in silicon (111) substrate surface for depositing thin layer carbon. We performed the deposition of carbon by using DC Unbalanced Magnetron Sputtering with carbon pallet (5% Fe) as target. From SEM characterization results it can be concluded that the carbon layer on HF treated substrate is more uniform than on substrate without treated. Carbon deposition rate is higher as confirmed by AFM results if the silicon substrate is treated by HF solution. EDAX characterization results tell that silicon (111) substrate with HF treatment have more carbon fraction than substrate without treatment. These results confirmed that HF treatment on silicon Si (111) substrates could enhance the carbon deposition by using DC sputtering. Afterward, the carbon atomic arrangement on silicon (111) surface is studied by performing thermal annealing process to 900 °C. From Raman spectroscopy results, thin film carbon is not changing until 600 °C thermal budged. But, when temperature increase to 900 °C, thin film carbon is starting to diffuse to silicon (111) substrates.

  4. Cyclic architecture of a carbonate sequence, early Aptian Shuaiba formation, Al Huwaisah field, Oman

    Energy Technology Data Exchange (ETDEWEB)

    Groetsch, J. (Shell Research, Rijswijk (Netherlands))

    1993-09-01

    Sequence stratigraphy of carbonates is a topic of ongoing controversy. In particular, small-scale shallowing-upward cycles can provide some key information needed for interpretation of carbonate sequences and/or third-order sea level changes. The early Aptian Shuaiba Formation in the Al Huwaisah field consists of about 90 m of shallow-water limestones. Throughout the formation, an overall decreasing influx of fine detritus is notable toward the top. The sequence can be subdivided into a basal unit and an overlying unit. Both units are composed of meter-scale shallowing-upward cycles of different composition, which can be recognized in core and well logs. Fourier analysis of the first principle component of a set of well logs (GR, FDC, CNL, Sonic) revealed an abrupt change in spectral behavior between the two units. Toward the top, the spectra are [open quotes]cleaning upward[close quotes] with an increasing pronunciation of a peak grouping of 1: 2: 5, suggesting a better preservation of orbital variations in the upper unit. Preservation of orbital forcing in shallowing-upward cycles requires rapid rates of sedimentation. In addition, increased shallow-water carbonate production on the platform is indicated by the appearance of reefal organisms. Hence, a higher rate of sedimentation and therefore a faster aggradation of the platform is inferred for the upper unit, which could have resulted from an increased rate of relative sea level rise. The sudden facies differentiation on the broad Arabian shelf in the upper part of the early Aptian reflects the development of an intrashelf basin. Changes in rate of relative sea level rise on the Arabian shelf might explain the repeated alternation from an easily correlatable ramp-type sedimentation, with slightly higher input of fine terrigenous sediment (e.g., lower unit of Shuaiba Formation) and a differentiation into platform and intrashelf basin facies due to faster aggradation (e.g., upper unit of Shuaiba Formation).

  5. Surface structure and adsorption properties of ultrafine porous carbon fibers

    International Nuclear Information System (INIS)

    Song Xiaofeng; Wang Ce; Zhang Dejiang

    2009-01-01

    Ultrafine porous carbon fibers (UPCFs) were successfully synthesized by chemical activation of electrospun polyacrylonitrile fibers. In the current approach, potassium hydroxide was adopted as activation reagent. UPCFs were systematically evaluated by scanning electron microscope and nitrogen adsorption. The mass ratio of potassium hydroxide to preoxidized fibers, activation temperature and activation time are crucial for producing high quality UPCFs. The relationships between porous structure and process parameters are explored. UPCFs were applied as adsorbent for nitrogen monoxide to be compared with commercial porous carbon fibers.

  6. Be{sub 2}C formation in beryllium-carbon binary system by vacuum heating

    Energy Technology Data Exchange (ETDEWEB)

    Ashida, Kan; Watanabe, Kuniaki [Toyama Univ. (Japan). Hydrogen Isotope Research Center

    1998-01-01

    The surface chemical states of beryllium and carbon binary systems at elevated temperature were investigated by means of x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The XPS measurements revealed that the mixed subsurface layers containing Be and C readily yield Be{sub 2}C layers by vacuum heating and ion bombardment. The SIMS measurements showed that hydrogen isotope atoms are trapped by three distinct sites; namely Be, C, and O-sites on the sample surface. The SIMS measurements also showed that carbon atoms lose its ability to bind with hydrogen isotope atoms on forming Be{sub 2}C. It would be a key to control hydrogen inventory when Be and C are used together as PFM. (author)

  7. Surface treatment of glass substrates for the preparation of long-lived carbon stripper foils

    International Nuclear Information System (INIS)

    Takeuchi, Suehiro; Takekoshi, Eiko

    1981-02-01

    Glass substrates having uniformly distributed microscopic grains on the surfaces are useful to make long-lived carbon stripper foils for heavy ions. A method of surface treatment of glass substrates to form the surface structure is described. This method consists of precipitation of glass components, such as soda, onto the surfaces in a hot and humid atmosphere and a fogging treatment of forming microscopic grains of the precipitated substances. Some results of studies on the treatment conditions are also presented. (author)

  8. Evaluation of modified stainless steel surfaces targeted to reduce biofilm formation by common milk sporeformers.

    Science.gov (United States)

    Jindal, Shivali; Anand, Sanjeev; Huang, Kang; Goddard, Julie; Metzger, Lloyd; Amamcharla, Jayendra

    2016-12-01

    The development of bacterial biofilms on stainless steel (SS) surfaces poses a great threat to the quality of milk and other dairy products as the biofilm-embedded bacteria can survive thermal processing. Established biofilms offer cleaning challenges because they are resistant to most of the regular cleaning protocols. Sporeforming thermoduric organisms entrapped within biofilm matrix can also form heat-resistant spores, and may result in a long-term persistent contamination. The main objective of this study was to evaluate the efficacy of different nonfouling coatings [AMC 18 (Advanced Materials Components Express, Lemont, PA), Dursan (SilcoTek Corporation, Bellefonte, PA), Ni-P-polytetrafluoroethylene (PTFE, Avtec Finishing Systems, New Hope, MN), and Lectrofluor 641 (General Magnaplate Corporation, Linden, NJ)] on SS plate heat exchanger surfaces, to resist the formation of bacterial biofilms. It was hypothesized that modified SS surfaces would promote a lesser amount of deposit buildup and bacterial adhesion as compared with the native SS surface. Vegetative cells of aerobic sporeformers, Geobacillus stearothermophilus (ATCC 15952), Bacillus licheniformis (ATCC 6634), and Bacillus sporothermodurans (DSM 10599), were used to study biofilm development on the modified and native SS surfaces. The adherence of these organisms, though influenced by surface energy and hydrophobicity, exhibited no apparent relation with surface roughness. The Ni-P-PTFE coating exhibited the least bacterial attachment and milk solid deposition, and hence, was the most resistant to biofilm formation. Scanning electron microscopy, which was used to visualize the extent of biofilm formation on modified and native SS surfaces, also revealed lower bacterial attachment on the Ni-P-PTFE as compared with the native SS surface. This study thus provides evidence of reduced biofilm formation on the modified SS surfaces. Copyright © 2016 American Dairy Science Association. Published by Elsevier

  9. Surface and electron emission properties of hydrogen-free diamond-like carbon films investigated by atomic force microscopy

    International Nuclear Information System (INIS)

    Liu Dongping; Zhang, Sam; Ong, S.-E.; Benstetter, Guenther; Du Hejun

    2006-01-01

    In this study, we have deposited hydrogen-free diamond-like carbon (DLC) films by using DC magnetron sputtering of graphite target at various r.f. bias voltages. Surface and nanoscale emission properties of these DLC films have been investigated using a combination of atomic force microscopy (AFM)-based nanowear tests and conducting-AFM, by simultaneously measuring the topography and the conductivity of the samples. Nanowear tests show that these DLC films are covered with the thin (1.5-2.0 nm) graphite-like layers at surfaces. Compared to the film bulk structure, the graphite-like surface layers are more conductive. The graphite-like surface layers significantly influence the electron emission properties of these films. Low-energy carbon species can be responsible for the formation of graphite-like surface layers. Nanoscale electron emission measurements have revealed the inhomogeneous emission nature of these films. The low-field emission from these films can be attributed to the existence of sp 2 -configured nanoclusters inside the films

  10. Delayed frost formation on hybrid nanostructured surfaces with patterned high wetting contrast

    Science.gov (United States)

    Hou, Youmin; Zhou, Peng; Yao, Shuhuai

    2014-11-01

    Engineering icephobic surfaces that can retard the frost formation and accumulation are important to vehicles, wind turbines, power lines, and HVAC systems. For condensation frosting, superhydrophobic surfaces promote self-removal of condensed droplets before freezing and consequently delay the frost growth. However, a small thermal fluctuation may lead to a Cassie-to-Wenzel transition, and thus dramatically enhance the frost formation and adhesion. In this work, we investigated the heterogeneous ice nucleation on hybrid nanostructured surfaces with patterned high wetting contrast. By judiciously introducing hydrophilic micro-patches into superhydrophobic nanostructured surface, we demonstrated that such a novel hybrid structure can efficiently defer the ice nucleation as compared to a superhydrophobic surface with nanostructures only. We observed efficient droplet jumping and higher coverage of droplets with diameter smaller than 10 μm, both of which suppress frost formation. The hybrid surface avoids the formation of liquid-bridges for Cassie-to-Wenzel transition, therefore eliminating the `bottom-up' droplet freezing from the cold substrate. These findings provide new insights to improve anti-frosting and anti-icing by using heterogeneous wettability in multiscale structures.

  11. Genetic adaptation of Streptococcus mutans during biofilm formation on different types of surfaces

    Directory of Open Access Journals (Sweden)

    Aharoni Reuven

    2010-02-01

    Full Text Available Abstract Background Adhesion and successful colonization of bacteria onto solid surfaces play a key role in biofilm formation. The initial adhesion and the colonization of bacteria may differ between the various types of surfaces found in oral cavity. Therefore, it is conceivable that diverse biofilms are developed on those various surfaces. The aim of the study was to investigate the molecular modifications occurring during in vitro biofilm development of Streptococcus mutans UA159 on several different dental surfaces. Results Growth analysis of the immobilized bacterial populations generated on the different surfaces shows that the bacteria constructed a more confluent and thick biofilms on a hydroxyapatite surface compared to the other tested surfaces. Using DNA-microarray technology we identified the differentially expressed genes of S. mutans, reflecting the physiological state of biofilms formed on the different biomaterials tested. Eight selected genes were further analyzed by real time RT-PCR. To further determine the impact of the tested material surfaces on the physiology of the bacteria, we tested the secretion of AI-2 signal by S. mutans embedded on those biofilms. Comparative transcriptome analyses indicated on changes in the S. mutans genome in biofilms formed onto different types of surfaces and enabled us to identify genes most differentially expressed on those surfaces. In addition, the levels of autoinducer-2 in biofilms from the various tested surfaces were different. Conclusions Our results demonstrate that gene expression of S. mutans differs in biofilms formed on tested surfaces, which manifest the physiological state of bacteria influenced by the type of surface material they accumulate onto. Moreover, the stressful circumstances of adjustment to the surface may persist in the bacteria enhancing intercellular signaling and surface dependent biofilm formation.

  12. Surface alloy formation by adsorption of holmium on Ag/Mo(112) bimetallic surfaces

    Science.gov (United States)

    Kołaczkiewicz, Jan; Oleksy, Czesław

    2018-03-01

    Work function change measurements, low energy electron diffraction (LEED) and density functional theory (DFT) are used to determine the structures formed on Ag/Mo(112) bimetallic surfaces upon deposition of 0.5 monolayer (ML) of holmium. As the bimetallic surfaces, we have chosen the Mo(112) substrate covered with 1 or 2 ML of Ag. Such surfaces have the same symmetry as the Mo(112) face but different electronic properties. LEED experiment indicates that the c(2 × 2) structure is formed on (1 ML Ag)/Mo(112) bimetallic surface upon deposition of 0.5 ML of Ho. DFT calculations show that a type of Ag-Ho surface alloy is formed, with Ho atoms 0.6 Å below the distorted layer of Ag. This is neither a substitutional nor a subsurface alloy. It is found that the adsorption structure formed on the (2 ML Ag)/Mo(112) bimetallic surface depends on the annealing temperature. After deposition of 0.5 ML of Ho at 300 K, the LEED pattern of p(2 × 2) symmetry is observed. Annealing of the overlayer at 640 K irreversibly changes the p(2 × 2) pattern into a pattern of c(2 × 2) type. The results of DFT computations show that the c(2 × 2) structure of the Ag-Ho surface alloy is energetically most favorable. In this structure, 0.5 ML of Ho is between the two monolayers of Ag, and the symmetry of the topmost layer is changed. The work function change calculated for the c(2 × 2) structure is in a good agreement with the measured value (0.22 eV). The results show that adsorption of Ho on the Ag/Mo(112) bimetallic surfaces is substantially different than on the clean Mo(112).

  13. Modeling uranium(VI) adsorption onto montmorillonite under varying carbonate concentrations: A surface complexation model accounting for the spillover effect on surface potential

    Science.gov (United States)

    Tournassat, C.; Tinnacher, R. M.; Grangeon, S.; Davis, J. A.

    2018-01-01

    The prediction of U(VI) adsorption onto montmorillonite clay is confounded by the complexities of: (1) the montmorillonite structure in terms of adsorption sites on basal and edge surfaces, and the complex interactions between the electrical double layers at these surfaces, and (2) U(VI) solution speciation, which can include cationic, anionic and neutral species. Previous U(VI)-montmorillonite adsorption and modeling studies have typically expanded classical surface complexation modeling approaches, initially developed for simple oxides, to include both cation exchange and surface complexation reactions. However, previous models have not taken into account the unique characteristics of electrostatic surface potentials that occur at montmorillonite edge sites, where the electrostatic surface potential of basal plane cation exchange sites influences the surface potential of neighboring edge sites ('spillover' effect). A series of U(VI) - Na-montmorillonite batch adsorption experiments was conducted as a function of pH, with variable U(VI), Ca, and dissolved carbonate concentrations. Based on the experimental data, a new type of surface complexation model (SCM) was developed for montmorillonite, that specifically accounts for the spillover effect using the edge surface speciation model by Tournassat et al. (2016a). The SCM allows for a prediction of U(VI) adsorption under varying chemical conditions with a minimum number of fitting parameters, not only for our own experimental results, but also for a number of published data sets. The model agreed well with many of these datasets without introducing a second site type or including the formation of ternary U(VI)-carbonato surface complexes. The model predictions were greatly impacted by utilizing analytical measurements of dissolved inorganic carbon (DIC) concentrations in individual sample solutions rather than assuming solution equilibration with a specific partial pressure of CO2, even when the gas phase was

  14. The role of evaporites in the formation of gems during metamorphism of carbonate platforms: a review

    Science.gov (United States)

    Giuliani, Gaston; Dubessy, Jean; Ohnenstetter, Daniel; Banks, David; Branquet, Yannick; Feneyrol, Julien; Fallick, Anthony E.; Martelat, Jean-Emmanuel

    2018-01-01

    The mineral and fluid inclusions trapped by gemstones during the metamorphism of carbonate platform successions are precious markers for the understanding of gem genesis. The nature and chemical composition of inclusions highlight the major contribution of evaporites through dissolution or fusion, depending on the temperature of formation from greenschist to granulite facies. The fluids are highly saline NaCl-brines circulating either in an open system in the greenschist facies (Colombian and Afghan emeralds) and with huge fluid-rock metasomatic interactions, or sulphurous fluids (ruby, garnet tsavorite, zoisite tanzanite and lapis-lazuli) or molten salts formed in a closed system with a low fluid mobility (ruby in marble) in the conditions of the amphibolite to granulite facies. These chloride-fluoride-sulphate ± carbonate-rich fluids scavenged the metals essential for gem formation. At high temperature, the anions SO4 2-, NO3 -, BO3 - and F- are powerful fluxes which lower the temperature of chloride- and fluoride-rich ionic liquids. They provided transport over a very short distance of aluminium and/or silica and transition metals which are necessary for gem growth. In summary, the genetic models proposed for these high-value and ornamental gems underline the importance of the metamorphism of evaporites formed on continental carbonate shelves and emphasise the chemical power accompanying metamorphism at moderate to high temperatures of evaporite-rich and organic matter-rich protoliths to form gem minerals.

  15. Electrochemical carbon dioxide reduction on rough copper surfaces

    NARCIS (Netherlands)

    Kas, Recep

    2016-01-01

    Sustainable development and climate change is considered to be one of the top challenges of humanity. Electrochemical carbon dioxide (CO2) reduction to fuels or fuel precursor using renewable electricity is a very promising way to recycle CO2 and store the electricity. This would also provide

  16. A Study of Atmospheric Plasma Treatment on Surface Energetics of Carbon Fibers

    International Nuclear Information System (INIS)

    Park, Soo Jin; Chang, Yong Hwan; Moon, Cheol Whan; Suh, Dong Hack; Im, Seung Soon; Kim, Yeong Cheol

    2010-01-01

    In this study, the atmospheric plasma treatment with He/O 2 was conducted to modify the surface chemistry of carbon fibers. The effects of plasma treatment parameters on the surface energetics of carbon fibers were experimentally investigated with respect to gas flow ratio, power intensity, and treatment time. Surface characteristics of the carbon fibers were determined by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), Fourier transform infrared (FT-IR), Zeta-potential, and contact angle measurements. The results indicated that oxygen plasma treatment led to a large amount of reactive functional groups onto the fiber surface, and these groups can form together as physical intermolecular bonding to improve the surface wettability with a hydrophilic polymer matrix

  17. Nanoscale analysis of the morphology and surface stability of calcium carbonate polymorphs

    Science.gov (United States)

    Sekkal, W.; Zaoui, A.

    2013-04-01

    Under earth surface conditions, in ocean and natural water, calcium carbonate is ubiquitous, forming anhydrous and hydrous minerals. These hydrous phases are of considerable interest for their role as precursors to stable carbonate minerals. Atomistic simulation techniques have been employed here to perform a comprehensive and quantitative study of the structural and energetic stability of dry and hydrous surfaces of calcium carbonate polymorphs using two recently developed forcefields. Results show that the dry forms are prone to ductility; while hydrous phases are found to be brittle. The (001) surface of monohydrocalcite appears to be the most stable (0.99 J/m2) whereas for the ikaite phase, the (001) surface is the most stable. The corresponding value is 0.2 J/m2, i.e. even lower than the surface energy of the Beautiful computed morphology pictures are obtained with Xiao's model and are very similar to the observed SEM images.

  18. Thermal Diffusion Processes in Metal-Tip-Surface Interactions: Contact Formation and Adatom Mobility

    DEFF Research Database (Denmark)

    Sørensen, Mads Reinholdt; Jacobsen, Karsten Wedel; Jonsson, Hannes

    1996-01-01

    and the surface can occur by a sequence of atomic hop and exchange processes which become active on a millisecond time scale when the tip is about 3-5 Angstrom from the surface. Adatoms on the surface are stabilized by the presence of the tip and energy barriers for diffusion processes in the region under the tip......We have carried out computer simulations to identify and characterize various thermally activated atomic scale processes that can play an important role in room temperature experiments where a metal tip is brought close to a metal surface. We find that contact formation between the tip...

  19. Cinnamon Oil and Chitosan Coating on Orthopaedic Implant Surface for Prevention of Staphylococcus Epidermidis Biofilm Formation

    OpenAIRE

    R Magetsari; P Dewo; BK Saputro; Z Lanodiyu

    2014-01-01

    S. Epidermidis is among the most frequently isolated microorganisms found in -infection related to implanted devices and the formation of biofilm will be more resistantcompared to the planktonic form. This study was carried out determine the effect of coating on stainless steel orthopaedic implants surfaces with cinnamon oil and chitosan as bioadhesive to prevent biofilms formation of S. Epidermidis.The rod shaped stainless steel 316 L orthopaedic implant with 5 mm diameters was coated 2 t...

  20. Adhesion, biofilm formation, cell surface hydrophobicity, and antifungal planktonic susceptibility: relationship among Candida spp.

    OpenAIRE

    Silva-Dias, Ana; Miranda, Isabel M.; Branco, Joana; Monteiro-Soares, Matilde; Pina-Vaz, Cid?lia; Rodrigues, Ac?cio G.

    2015-01-01

    We have performed the characterization of the adhesion profile, biofilm formation, cell surface hydrophobicity (CSH) and antifungal susceptibility of 184 Candida clinical isolates obtained from different human reservoirs. Adhesion was quantified using a flow cytometric assay and biofilm formation was evaluated using two methodologies: XTT and crystal violet assay. CSH was quantified with the microbial adhesion to hydrocarbons test while planktonic susceptibility was assessed accordingly the C...

  1. Microwave plasma induced surface modification of diamond-like carbon films

    Science.gov (United States)

    Rao Polaki, Shyamala; Kumar, Niranjan; Gopala Krishna, Nanda; Madapu, Kishore; Kamruddin, Mohamed; Dash, Sitaram; Tyagi, Ashok Kumar

    2017-12-01

    Tailoring the surface of diamond-like carbon (DLC) film is technically relevant for altering the physical and chemical properties, desirable for useful applications. A physically smooth and sp3 dominated DLC film with tetrahedral coordination was prepared by plasma-enhanced chemical vapor deposition technique. The surface of the DLC film was exposed to hydrogen, oxygen and nitrogen plasma for physical and chemical modifications. The surface modification was based on the concept of adsorption-desorption of plasma species and surface entities of films. Energetic chemical species of microwave plasma are adsorbed, leading to desorbtion of the surface carbon atoms due to energy and momentum exchange. The interaction of such reactive species with DLC films enhanced the roughness, surface defects and dangling bonds of carbon atoms. Adsorbed hydrogen, oxygen and nitrogen formed a covalent network while saturating the dangling carbon bonds around the tetrahedral sp3 valency. The modified surface chemical affinity depends upon the charge carriers and electron covalency of the adsorbed atoms. The contact angle of chemically reconstructed surface increases when a water droplet interacts either through hydrogen or van dear Waals bonding. These weak interactions influenced the wetting property of the DLC surface to a great extent.

  2. Erosion of pyrolytic carbon under high surface energy deposition from a pulsed hydrogen plasma

    International Nuclear Information System (INIS)

    Bolt, H.

    1992-01-01

    Carbon materials are widely applied as plasma facing materials in nuclear fusion devices and are also the prime candidate materials for the next generation of experimental fusion reactors. During operation these materials are frequently subjected to high energy deposition from plasma disruptions. The erosion of carbon materials is regarded as the main issue governing the operational lifetime of plasma facing components. Laboratory experiments have been performed to study the thermal erosion behaviour of carbon in a plasma environment. In the experiments the surface of pyrolytic carbon specimens was exposed to pulsed energy deposition of up to 3.8 MJ m -2 from a hydrogen plasma. The behaviour of the eroded carbon species in the plasma was measured by time-resolved and space-resolved spectroscopy. Intense line radiation of ionic carbon has been measured in the plasma in front of the carbon surface. The results show that the eroded carbon is immediately ionised in the vicinity of the material surface, with a fraction of it being ionised to the double-charged state. (Author)

  3. The Effect of Laser Surface Reconstruction of Disordered Carbons on Performance

    International Nuclear Information System (INIS)

    EVEN JR., WILLIAM R.; GUIDOTTI, RONALD A.

    1999-01-01

    The reconstruction of the surface of disordered carbons was examined by heating carbons derived from polymethacrylonitrile (PMAN) and divinylbenzene (DVB) with a pulsed infrared laser in an argon or helium atmosphere, both fluidized and under static conditions. By graphitizing the outer surface of the carbons, it was hoped to reduce the high first-cycle losses associated with such disordered materials in Li-ion cells. The power to the sample was varied to observed the effects on surface morphology and electrochemical performance in 1M LiPF(sub 6) ethylene carbonate-dimethyl carbonate. The use various reactive atmosphere such as ethylene, 2-vinylpyridine, pyrrole, and furfuryl alcohol were also evaluated as an alternative means of hopefully forming a thin graphitic layer on the carbon particles to reduce first-cycle irreversibility. While some improvement was realized, these losses were still unacceptably high. The laser heating did improve the rate capabilities of the carbons, however. More work in this area is necessary to fully understand surface and bulk effects

  4. Surface nucleation and independent growth of Ce(OH)4 within confinement space on modified carbon black surface to prepare nano-CeO2 without agglomeration

    Science.gov (United States)

    Zhang, Xinyue; Xia, Chunhui; Li, Kaitao; Lin, Yanjun

    2018-04-01

    Highly dispersed negative carboxyl groups can be formed on carbon black (CB) surface modified with strong nitric acid. Therefore positive cations can be uniformly absorbed by carboxyl groups and precipitated within a confinement space on modified CB surface to prepare highly dispersed nanomaterials. In this paper, the formation and dispersion status of surface negative carboxyl groups, adsorption status of Ce3+, surface confinement nucleation, crystallization and calcination process were studied by EDS, SEM, and laser particle size analysis. The results show that the carboxyl groups formed on modified CB surface are highly dispersed, and Ce3+ cations can be uniformly anchored by carboxyl groups. Therefore, highly dispersed Ce3+ can react with OH- within a confinement surface region to form positive nano-Ce(OH)4 nuclei which also can be adsorbed by electrostatic attraction. After independent growth of Ce(OH)4 without agglomeration, highly dispersed CeO2 nanoparticles without agglomeration can be prepared together with the help of effectively isolates by CO2 released in the combustion of CB.

  5. Electrical Characteristics of Carbon Nanotubes by Plasma and Microwave Surface Treatments

    International Nuclear Information System (INIS)

    Cho, Sangjin; Lee, Soonbo; Boo, Jinhyo; Shrestha, Shankar Prasad

    2014-01-01

    The plasma and microwave surface treatments of carbon nanotubes that loaded on plastic substrates were carried out with expecting a change of carbon nanotube dispersion by increasing treatment time. The microwave treatment process was undergone by commercial microwave oven (800 W). The electrical property was measured by hall measurement and resistance was increased by increasing O 2 flow rate of plasma, suggesting an improvement of carbon nanotube dispersion and a possibility of controlling the resistances of carbon nanotubes by plasma surface treatment. The resistance was increased in both polyethylene terephthalate and polyimide substrates by increasing O 2 flow rate. Resistance changes only slightly with different O 2 flow treatment in measure rho for all polyimide samples. Sheet resistance is lowest in polyimide substrate not due to high carbon nanotube loading but due to tendency to remain in elongated structure. O 2 or N 2 plasma treatments on both polyethylene terephthalate and polyimide substrates lead to increase in sheet resistance

  6. Formation of self-assembled monolayer of curcuminoid molecules on gold surfaces

    International Nuclear Information System (INIS)

    Berlanga, Isadora; Etcheverry-Berríos, Álvaro; Mella, Andy; Jullian, Domingo; Gómez, Victoria Alejandra; Aliaga-Alcalde, Núria; Fuenzalida, Victor; Flores, Marcos

    2017-01-01

    Highlights: • Thiophene curcuminoid molecules deposited on a gold surface by immersion. • Molecular dynamic studies of the molecular arrangement approaching the surface. • XPS and STM studies showing different arrangement of the molecules on the surface. • Molecular Interaction with surface depends on the sulfur position in thiophene rings. • Temporal evolution of the molecular arrangement on the surface. - Abstract: We investigated the formation of self-assembled monolayers of two thiophene curcuminoid molecules, 2-thphCCM (1) and 3-thphCCM (2), on polycrystalline gold substrates prepared by immersion of the surfaces in a solution of the molecules during 24 h. The functionalized surfaces were studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Despite the fact that both molecules have the same composition and almost the same structure, these molecules exhibit different behavior on the gold surface, which can be explained by the different positions of the sulfur atoms in the terminal aromatic rings. In the case of molecule 1, the complete formation of a SAM can be observed after 24 h of immersion. In the case of molecule 2, the transition from flat-lying to upright configuration on the surface is still in process after 24 h of immersion. This is attributed to the fact that molecule 2 have the sulfur atoms more exposed than molecule 1.

  7. Formation of self-assembled monolayer of curcuminoid molecules on gold surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Berlanga, Isadora [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); Etcheverry-Berríos, Álvaro; Mella, Andy; Jullian, Domingo [Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Beaucheff 851, Santiago (Chile); Gómez, Victoria Alejandra [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); Aliaga-Alcalde, Núria [ICREA (Institució Catalana de Recerca i Estudis Avançats), Passeig Lluís Companys, 23, 08018, Barcelona (Spain); CSIC-ICMAB (Institut de Ciència dels Materials de Barcelona), Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra (Spain); Fuenzalida, Victor [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); Flores, Marcos, E-mail: mflorescarra@ing.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Blanco Encalada 2008, Santiago (Chile); and others

    2017-01-15

    Highlights: • Thiophene curcuminoid molecules deposited on a gold surface by immersion. • Molecular dynamic studies of the molecular arrangement approaching the surface. • XPS and STM studies showing different arrangement of the molecules on the surface. • Molecular Interaction with surface depends on the sulfur position in thiophene rings. • Temporal evolution of the molecular arrangement on the surface. - Abstract: We investigated the formation of self-assembled monolayers of two thiophene curcuminoid molecules, 2-thphCCM (1) and 3-thphCCM (2), on polycrystalline gold substrates prepared by immersion of the surfaces in a solution of the molecules during 24 h. The functionalized surfaces were studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Despite the fact that both molecules have the same composition and almost the same structure, these molecules exhibit different behavior on the gold surface, which can be explained by the different positions of the sulfur atoms in the terminal aromatic rings. In the case of molecule 1, the complete formation of a SAM can be observed after 24 h of immersion. In the case of molecule 2, the transition from flat-lying to upright configuration on the surface is still in process after 24 h of immersion. This is attributed to the fact that molecule 2 have the sulfur atoms more exposed than molecule 1.

  8. Effect of carbon nanofiber surface morphology on convective heat transfer from cylindrical surface: Synthesis, characterization and heat transfer measurement

    NARCIS (Netherlands)

    Taha, T.J.; Mojet, Barbara; Lefferts, Leonardus; van der Meer, Theodorus H.

    2016-01-01

    In this work, heat transfer surface modification is made by layers of carbon nanofiber (CNF) on a 50 μm nickel wire using Thermal chemical vapor deposition process (TCVD). Three different CNF layer morphologies are made, at 500 °C, 600 °C and 700 °C, to investigate the influence of morphology on

  9. Interlaminar and ductile characteristics of carbon fibers-reinforced plastics produced by nanoscaled electroless nickel plating on carbon fiber surfaces.

    Science.gov (United States)

    Park, Soo-Jin; Jang, Yu-Sin; Rhee, Kyong-Yop

    2002-01-15

    In this work, a new method based on nanoscaled Ni-P alloy coating on carbon fiber surfaces is proposed for the improvement of interfacial properties between fibers and epoxy matrix in a composite system. Fiber surfaces and the mechanical interfacial properties of composites were characterized by atomic absorption spectrophotometer (AAS), scanning electron microscopy (SEM), X-ray photoelectron spectrometry (XPS), interlaminar shear strength (ILSS), and impact strength. Experimental results showed that the O(1s)/C(1s) ratio or Ni and P amounts had been increased as the electroless nickel plating proceeded; the ILSS had also been slightly improved. The impact properties were significantly improved in the presence of Ni-P alloy on carbon fiber surfaces, increasing the ductility of the composites. This was probably due to the effect of substituted Ni-P alloy, leading to an increase of the resistance to the deformation and the crack initiation of the epoxy system.

  10. Surface and corrosion characteristics of carbon plasma implanted and deposited nickel-titanium alloy

    International Nuclear Information System (INIS)

    Poon, R.W.Y.; Liu, X.Y.; Chung, C.Y.; Chu, P.K.; Yeung, K.W.K.; Lu, W.W.; Cheung, K.M.C.

    2005-01-01

    Nickel-titanium shape memory alloys (NiTi) are potentially useful in orthopedic implants on account of their super-elastic and shape memory properties. However, the materials are prone to surface corrosion and the most common problem is out-diffusion of harmful Ni ions from the substrate into body tissues and fluids. In order to improve the corrosion resistance and related surface properties, we used the technique of plasma immersion ion implantation and deposition to deposit an amorphous hydrogenated carbon coating onto NiTi and implant carbon into NiTi. Both the deposited amorphous carbon film and carbon plasma implanted samples exhibit much improved corrosion resistances and surface mechanical properties and possible mechanisms are suggested

  11. Delayed condensation and frost formation on superhydrophobic carbon soot coatings by controlling the presence of hydrophilic active sites

    Science.gov (United States)

    Esmeryan, Karekin D.; Castano, Carlos E.; Mohammadi, Reza; Lazarov, Yuliyan; Radeva, Ekaterina I.

    2018-02-01

    Condensation frosting is an undesired natural phenomenon that could be impeded efficiently using appropriate wettability and morphologically patterned surfaces. The icephobic properties of carbon soot and the fabrication scalability of its synthesis method are a good foundation for anti-frosting applications; however, the fundamentals of frost growth and spreading on sooted surfaces have not been examined yet. In this study, we investigate the anti-frosting performance of three groups of superhydrophobic soot coatings by means of 16 MHz quartz crystal microbalances (QCMs). The analysis of the real-time sensor signal of each soot coated QCM pattern shows that frost formation and its propagation velocity depend on the quantity of oxygen functionalities and structural defects in the material. In turn, the reduction of both parameters shifts the onset of frost growth to temperatures below  -20 °C, whereas the interdroplet ice bridging is slowed by a factor of four. Moreover, high-resolution scanning electron micrographs of the samples imply delamination upon defrosting of the soot with spherical-like morphology via polar interactions driven mechanism. These results reveal an opportunity for control of frost incipiency on sooted surfaces by adjusting the synthesis conditions and depositing soot coatings with as low as possible content of hydrophilic active sites.

  12. Study on electroactive and electrocatalytic surfaces of single walled carbon nanotube-modified electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Salinas-Torres, David [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain); Huerta, Francisco [Departamento de Ingenieria Textil y Papelera, Universidad Politecnica de Valencia, Plaza Ferrandiz y Carbonell, 1. E-03801 Alcoy (Spain); Montilla, Francisco, E-mail: francisco.montilla@ua.e [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain); Morallon, Emilia [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain)

    2011-02-01

    An investigation of the electrocatalysis of single-walled carbon nanotubes modified electrodes has been performed in this work. Nanotube-modified electrodes present a surface area much higher than the bare glassy carbon surfaces as determined by capacitance measurements. Several redox probes were selected for checking the reactivity of specific sites at the carbon nanotube surface. The presence of carbon nanotubes on the electrode improves the kinetics for all the reactions studied compared with the bare glassy carbon electrode with variations of the heterogeneous electron transfer rate constant up to 5 orders of magnitude. The most important effects are observed for the benzoquinone/hydroquinone and ferrocene/ferricinium redox couples, which show a remarkable improvement of their electron transfer kinetics on SWCNT-modified electrodes, probably due to strong {pi}-{pi} interaction between the organic molecules and the walls of the carbon nanotubes. For many of the reactions studied, less than 1% of the nanotube-modified electrode surface is transferring charge to species in solution. This result suggests that only nanotube tips are active sites for the electron transfer in such cases. On the contrary, the electroactive surface for the reactions of ferrocene and quinone is higher indicating that the electron transfer is produced also from the nanotube walls.

  13. Study on electroactive and electrocatalytic surfaces of single walled carbon nanotube-modified electrodes

    International Nuclear Information System (INIS)

    Salinas-Torres, David; Huerta, Francisco; Montilla, Francisco; Morallon, Emilia

    2011-01-01

    An investigation of the electrocatalysis of single-walled carbon nanotubes modified electrodes has been performed in this work. Nanotube-modified electrodes present a surface area much higher than the bare glassy carbon surfaces as determined by capacitance measurements. Several redox probes were selected for checking the reactivity of specific sites at the carbon nanotube surface. The presence of carbon nanotubes on the electrode improves the kinetics for all the reactions studied compared with the bare glassy carbon electrode with variations of the heterogeneous electron transfer rate constant up to 5 orders of magnitude. The most important effects are observed for the benzoquinone/hydroquinone and ferrocene/ferricinium redox couples, which show a remarkable improvement of their electron transfer kinetics on SWCNT-modified electrodes, probably due to strong π-π interaction between the organic molecules and the walls of the carbon nanotubes. For many of the reactions studied, less than 1% of the nanotube-modified electrode surface is transferring charge to species in solution. This result suggests that only nanotube tips are active sites for the electron transfer in such cases. On the contrary, the electroactive surface for the reactions of ferrocene and quinone is higher indicating that the electron transfer is produced also from the nanotube walls.

  14. Carbon/hydrogen clusters [CnHx+] formation from laser irradiation of coronene

    International Nuclear Information System (INIS)

    Betancourt, F; Alvarez, I; Guerrero, A; Cisneros, C; Poveda, J C

    2015-01-01

    This article presents the photo induced dehydrogenation of a cooled molecular jet of coronene, exposed to 266 nm laser radiation. Using unfocused laser radiation of 1064 nm, synchronously coupled with the ionization laser pulses, a system recently developed. Molecular beams were produced by laser desorption of coronene. Analysis of the photoproducts made by time-of flight mass spectrometer showed that a wide variety of ionic species were formed; more than 300 different species were observed. The results showed carbon clusters C + n with n up to 24 as well as carbon/hydrogen clusters C + n H + x with masses higher than 300 m/z. The effect on the laser irradiance on the formation of different ions, in the rage from 10 9 W/cm2 to 10 10 W/cm2, is discussed as it is reflected on the evolution from the big ions to the smaller ones. (paper)

  15. Carbon distribution during plasma detachment triggered by edge magnetic island formation in LHD

    International Nuclear Information System (INIS)

    Dong, C.F.; Morita, S.; Kobayashi, M.; Oishi, T.; Goto, M.; Wang, E.H.; Huang, X.L.

    2013-01-01

    The detached plasma has been successfully achieved by applying the edge 1/1 magnetic island in Large Helical Device (LHD). Carbon, which is uniquely the dominant intrinsic impurity in general LHD discharges, is considered to be the main radiating species in the island-triggered detached plasma. The vertical profile of CIV measured from general discharges of LHD is characterized by a single edge intensity peak. In detached plasmas triggered by the edge magnetic island formation, however, the vertical profile of CIV shows a significant difference. Double edge peaks of CIV are found during the plasma detachment and the CIV radiation is also remarkably enhanced in the vicinity of X-point, whereas the vertical profile of CVI does not show any significant difference in both the attached and detached plasmas. In this proceeding the carbon distribution during the plasma detachment is presented and the results are discussed with edge magnetic field structure. (author)

  16. Migration rates and formation injectivity to determine containment time scales of sequestered carbon dioxide

    Science.gov (United States)

    Burke, Lauri

    2012-01-01

    Supercritical carbon dioxide exhibits highly variable behavior over a range of reservoir pressure and temperature conditions. Because geologic sequestration of supercritical carbon dioxide is targeted for subsurface injection and containment at depths ranging from approximately 3,000 to 13,000 feet, the investigation into the physical properties of this fluid can be restricted to the pressure and temperature conditions likely encountered in the sedimentary strata within this depth interval. A petrophysical based approach was developed to study the widest range of formation properties potentially encountered in sedimentary strata. Fractional porosities were varied from 5 to 95 percent, in 5-percent increments, and permeability values were varied over thirteen orders of magnitude, from 10.0 darcys down to 1.0 picodarcy.

  17. A coupled carbonation-rust formation mechanical damage model for steel corrosion in reinforced concrete

    International Nuclear Information System (INIS)

    Nguyen, Huyen; Bary, B.; L'Hostis, Valerie; DeLarrard, T.

    2014-01-01

    This paper aims at presenting a strategy to simulate the corrosion of steel reinforcement due to carbonation of concrete in atmospheric environment. We propose a model coupling drying, carbonation, diffusion of oxygen, formation of rust and mechanics to describe these phenomena. The rust layer is assumed to be composed of two sub-layers with different elastic modulus. An unstable layer with a low modulus (from 0.1 to 5 GPa) is located next to the transformed medium, and another more stable one with a higher modulus (from 100 to 150 GPa) at the interface with steel reinforcement. This model is applied to a numerical meso-structure composed of 4 phases: mortar matrix, randomly distributed aggregates, steel rebar and rust layers to underline the effect of aggregates on damage initiation and corresponding crack pattern of concrete cover. (authors)

  18. Study of LiFePO{sub 4} cathode materials coated with high surface area carbon

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Cheng-Zhang; Fey, George Ting-Kuo [Department of Chemical and Materials Engineering, National Central University, Chung-Li 32054 (China); Kao, Hsien-Ming [Department of Chemistry, National Central University, Chung-Li 32054 (China)

    2009-04-01

    LiFePO{sub 4} is a potential cathode material for 4 V lithium-ion batteries. Carbon-coated lithium iron phosphates were prepared using a high surface area carbon to react precursors through a solid-state process, during which LiFePO{sub 4} particles were embedded in amorphous carbon. The carbonaceous materials were synthesize