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Sample records for covalently doped dlc

  1. Ion beam deposition of DLC and nitrogen doped DLC thin films for enhanced haemocompatibility on PTFE

    International Nuclear Information System (INIS)

    Srinivasan, S.; Tang, Y.; Li, Y.S.; Yang, Q.; Hirose, A.

    2012-01-01

    Diamond-like carbon (DLC) and N-doped DLC (DLC:N) thin films have been synthesized on polytetrafluroethylene (PTFE) and silicon wafers using ion beam deposition. Raman spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were used to study the structural and morphological properties of the coated surface. The results show that the ion beam deposited DLC thin films exhibit high hardness and Young's modulus, low coefficient of friction and high adhesion to the substrate. Low concentration of nitrogen doping in DLC improves the mechanical properties and reduces the surface roughness. DLC coating decreases the surface energy and improves the wettability of PTFE. The platelet adhesion results show that the haemocompatibility of DLC coated PTFE, especially DLC:N coated PTFE, has been significantly enhanced as compared with uncoated PTFE. SEM observations show that the platelet reaction on the DLC and DLC:N coated PTFE was minimized as the platelets were much less aggregated and activated.

  2. Electron field emission from undoped and doped DLC films

    International Nuclear Information System (INIS)

    Chakhovskoi, A G; Evtukh, A A; Felter, T E; Klyui, N I; Kudzinovsky, S Y; Litovchenko, V G; Litvin, Y M

    1999-01-01

    Electron field emission and electrical conductivity of undoped and nitrogen doped DLC films have been investigated. The films were grown by the PE CVD method from CH(sub 4):H(sub 2) and CH(sub 4):H(sub 2):N(sub 2) gas mixtures, respectively. By varying nitrogen content in the gas mixture over the range 0 to 45%, corresponding concentrations of 0 to 8% (atomic) could be achieved in the films. Three different gas pressures were used in the deposition chamber: 0.2, 0.6 and 0.8 Torr. Emission current measurements were performed at approximately 10(sup -6) Torr using the diode method with emitter-anode spacing set at 20(micro)m. The current - voltage characteristics of the Si field electron emission arrays covered with DLC films show that threshold voltage (V(sub th)) varies in a complex manner with nitrogen content. As a function of nitrogen content, V(sub th) initially increases rapidly, then decreases and finally increases again for the highest concentration. Corresponding Fowler-Nordheim (F-N) plots follow F-N tunneling over a wide range. The F-N plots were used for determination of the work function, threshold voltage, field enhancement factor and effective emission area. For a qualitative explanation of experimental results, we treat the DLC film as a diamond-like (sp(sup 3) bonded) matrix with graphite-like inclusions

  3. Mo doped DLC nanocomposite coatings with improved mechanical and blood compatibility properties

    Energy Technology Data Exchange (ETDEWEB)

    Tang, X.S. [School of Physics Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China); Development Center for New Materials Engineering and Technology in Universities of Guangdong, Zhanjiang 524048 (China); Wang, H.J.; Feng, L. [School of Physics Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China); Shao, L.X. [School of Physics Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China); Development Center for New Materials Engineering and Technology in Universities of Guangdong, Zhanjiang 524048 (China); Zou, C.W., E-mail: qingyihaiyanas@163.com [School of Physics Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China); Development Center for New Materials Engineering and Technology in Universities of Guangdong, Zhanjiang 524048 (China)

    2014-08-30

    Highlights: • Mo doped diamond like carbon coatings were deposited by magnetron sputtering. • The blood compatibility of Mo-DLC coatings was observed through platelet adhesion. • The amount of thrombus on the Mo-DLC is much less than that of pyrolytic carbon. - Abstract: Mo (molybdenum) doped diamond like carbon (Mo-DLC) coatings with improved mechanical and blood compatibility properties were deposited by closed field unbalanced magnetron sputtering. The undoped and Mo-doped DLC coatings were analyzed by various characterization techniques such as Raman spectra, Atomic force microscopy, and temperature-dependent frictional wear testing. The results showed that the Mo-DLC coating with low Mo concentration was a effective protective coating with reduced residual stress and increased cohesive strength, and kept good wear resistance at the ambient temperature of 500 °C. The blood compatibility of Mo-DLC coatings was investigated by platelet adhesion. The results showed that the amount of thrombus on the Mo-DLC nanocomposite coatings was much less than that of thrombus on pyrolytic carbon films. The Mo-DLC nanocomposite coatings would be a new kind of promising materials applied to artificial heart valve and endovascula stent.

  4. Mo doped DLC nanocomposite coatings with improved mechanical and blood compatibility properties

    International Nuclear Information System (INIS)

    Tang, X.S.; Wang, H.J.; Feng, L.; Shao, L.X.; Zou, C.W.

    2014-01-01

    Highlights: • Mo doped diamond like carbon coatings were deposited by magnetron sputtering. • The blood compatibility of Mo-DLC coatings was observed through platelet adhesion. • The amount of thrombus on the Mo-DLC is much less than that of pyrolytic carbon. - Abstract: Mo (molybdenum) doped diamond like carbon (Mo-DLC) coatings with improved mechanical and blood compatibility properties were deposited by closed field unbalanced magnetron sputtering. The undoped and Mo-doped DLC coatings were analyzed by various characterization techniques such as Raman spectra, Atomic force microscopy, and temperature-dependent frictional wear testing. The results showed that the Mo-DLC coating with low Mo concentration was a effective protective coating with reduced residual stress and increased cohesive strength, and kept good wear resistance at the ambient temperature of 500 °C. The blood compatibility of Mo-DLC coatings was investigated by platelet adhesion. The results showed that the amount of thrombus on the Mo-DLC nanocomposite coatings was much less than that of thrombus on pyrolytic carbon films. The Mo-DLC nanocomposite coatings would be a new kind of promising materials applied to artificial heart valve and endovascula stent

  5. Iron, nitrogen and silicon doped diamond like carbon (DLC) thin films: A comparative study

    International Nuclear Information System (INIS)

    Ray, Sekhar C.; Pong, W.F.; Papakonstantinou, P.

    2016-01-01

    The X-ray absorption near edge structure (XANES), X-ray photoelectron spectroscopy (XPS), valence band photoemission (VB-PES) and Raman spectroscopy results show that the incorporation of nitrogen in pulsed laser deposited diamond like carbon (DLC) thin films, reverts the sp"3 network to sp"2 as evidenced by an increase of the sp"2 cluster and I_D/I_G ratio in C K-edge XANES and Raman spectra respectively which reduces the hardness/Young's modulus into the film network. Si-doped DLC film deposited in a plasma enhanced chemical vapour deposition process reduces the sp"2 cluster and I_D/I_G ratio that causes the decrease of hardness/Young's modulus of the film structure. The Fe-doped DLC films deposited by dip coating technique increase the hardness/Young's modulus with an increase of sp"3-content in DLC film structure. - Highlights: • Fe, N and Si doped DLC films deposited by dip, PLD and PECVD methods respectively • DLC:Fe thin films have higher hardness/Young's modulus than DLC:N(:Si) thin films. • sp"3 and sp"2 contents are estimated from C K-edge XANES and VB-PES measurements.

  6. Iron, nitrogen and silicon doped diamond like carbon (DLC) thin films: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Sekhar C., E-mail: Raysc@unisa.ac.za [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Private Bag X6, Florida, 1710, Science Campus, Christiaan de Wet and Pioneer Avenue, Florida Park, Johannesburg (South Africa); Pong, W.F. [Department of Physics, Tamkang University, Tamsui 251, New Taipei City, Taiwan (China); Papakonstantinou, P. [Nanotechnology and Integrated Bio-Engineering Centre, University of Ulster, Shore Road, Newtownabbey BT37 0QB (United Kingdom)

    2016-07-01

    The X-ray absorption near edge structure (XANES), X-ray photoelectron spectroscopy (XPS), valence band photoemission (VB-PES) and Raman spectroscopy results show that the incorporation of nitrogen in pulsed laser deposited diamond like carbon (DLC) thin films, reverts the sp{sup 3} network to sp{sup 2} as evidenced by an increase of the sp{sup 2} cluster and I{sub D}/I{sub G} ratio in C K-edge XANES and Raman spectra respectively which reduces the hardness/Young's modulus into the film network. Si-doped DLC film deposited in a plasma enhanced chemical vapour deposition process reduces the sp{sup 2} cluster and I{sub D}/I{sub G} ratio that causes the decrease of hardness/Young's modulus of the film structure. The Fe-doped DLC films deposited by dip coating technique increase the hardness/Young's modulus with an increase of sp{sup 3}-content in DLC film structure. - Highlights: • Fe, N and Si doped DLC films deposited by dip, PLD and PECVD methods respectively • DLC:Fe thin films have higher hardness/Young's modulus than DLC:N(:Si) thin films. • sp{sup 3} and sp{sup 2} contents are estimated from C K-edge XANES and VB-PES measurements.

  7. Tribochemical interactions of Si-doped DLC film against steel in sliding contact

    International Nuclear Information System (INIS)

    Yoon, Eui Sung; Pham, Duc Cuong; Ahn, Hyo Sok; Oh, Jae Eung

    2007-01-01

    This study concerns the effects of tribochemical interactions at the interface of Si-DLC (silicon-doped diamond-like carbon) film and steel ball in sliding contact on tribological properties of the film. The Si-DLC film was over-coated on pure DLC coating by radio frequency plasma-assisted chemical vapor deposition (r.f. PACVD) with different Si concentration. Friction tests against steel ball using a reciprocating type tribotester were performed in ambient environment. X-Ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES) were used to study the chemical characteristics and elemental composition of the films and mating balls after tests. Results showed a darkgray film consisting of carbon, oxygen and silicon on the worn steel ball surface with different thickness. On the contrary, such film was not observed on the surface of the ball slid against pure DLC coating. The oxidation of Si-DLC surface and steel ball was also found at particular regions of contact area. This demonstrates that tribochemical interactions occurred at the contact area of Si-DLC and steel ball during sliding to form a tribofilm (so called transfer film) on the ball specimen. While the pure DLC coating exhibited high coefficient of friction (∼0.06), the Si-DLC film showed a significant lower coefficient of friction (∼0.022) with the presence of tribofilm on mating ball surface. However, the Si-DLC film possesses a very high wear rate in comparison with the pure DLC. It was found that the tribochemical interactions strongly affected tribological properties of the Si-DLC film in sliding against steel

  8. Chromium-doped DLC for implants prepared by laser-magnetron deposition.

    Science.gov (United States)

    Jelinek, Miroslav; Kocourek, Tomáš; Zemek, Josef; Mikšovský, Jan; Kubinová, Šárka; Remsa, Jan; Kopeček, Jaromir; Jurek, Karel

    2015-01-01

    Diamond-like carbon (DLC) thin films are frequently used for coating of implants. The problem of DLC layers lies in bad layer adhesion to metal implants. Chromium is used as a dopant for improvement of adhesion of DLC films. DLC and Cr-DLC layers were deposited on silicon, Ti6Al4V and CoCrMo substrates by a hybrid technology using combination of pulsed laser deposition (PLD) and magnetron sputtering. The topology of layers was studied using SEM, AFM and mechanical profilometer. Carbon and chromium content and concentration of trivalent and toxic hexavalent chromium bonds were determined by XPS and WDS. It follows from the scratch tests that Cr doping improved adhesion of DLC layers. Ethylene glycol, diiodomethane and deionized water were used to measure the contact angles. The surface free energy (SFE) was calculated. The antibacterial properties were studied using Pseudomonas aeruginosa and Staphylococcus aureus bacteria. The influence of SFE, hydrophobicity and surface roughness on antibacterial ability of doped layers is discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Synthesis and electrochemical properties of Ti-doped DLC films by a hybrid PVD/PECVD process

    Science.gov (United States)

    Jo, Yeong Ju; Zhang, Teng Fei; Son, Myoung Jun; Kim, Kwang Ho

    2018-03-01

    Low electrical conductivity and poor adhesion to metallic substrates are the main drawbacks of diamond-like carbon (DLC) films when used in electrode applications. In this study, Ti-doped DLC films with various Ti contents were synthesized on metal Ti substrates by a hybrid PVD/PECVD process, where PECVD was used for deposition of DLC films and PVD was used for Ti doping. The effects of the Ti doping ratio on the microstructure, adhesion strength, and electrical and electrochemical properties of the DLC films were systematically investigated. An increase in the Ti content led to increased surface roughness and a higher sp2/sp3 ratio of the Ti-DLC films. Ti atoms existed as amorphous-phase Ti carbide when the Ti doping ratio was less than 2.8 at.%, while the nanocrystalline TiC phase was formed in DLC films when the Ti doping ratio was exceeded 4.0 at.%. The adhesion strength, electrical resistivity, electrochemical activity and reversibility of the DLC films were greatly improved by Ti doping. The influence of Ti doping ratio on the electrical and electrochemical properties of the DLC films were also investigated and the best performance was obtained at a Ti content of 2.8 at.%.

  10. Electrochemical studies and growth of apatite on molybdenum doped DLC coatings on titanium alloy β-21S

    International Nuclear Information System (INIS)

    Anandan, C.; Mohan, L.; Babu, P. Dilli

    2014-01-01

    Highlights: • Titanium alloy β21S was coated with Mo doped DLC. • XRD, XPS and micro Raman show that Mo is present in the form of carbide. • Mo doping facilitates apatite growth on DLC during immersion in Hanks’ solution. • Mo doped DLC sample shows better passivation behavior in Hanks’ solution. - Abstract: Titanium alloy β-21S (Ti–15Mo–3Nb–3Al–0.2Si) was coated with molybdenum doped DLC by Plasma-enhanced chemical vapor deposition and sputtering. XRD, XPS and Raman spectroscopy show that Mo is present in the form of carbide in the coating. XPS of samples immersed in Hanks’ solution shows presence of calcium, phosphorous and oxygen in hydroxide/phosphate form on the substrate and Mo-doped DLC. Potentiodynamic polarization studies show that the corrosion resistance and passivation behavior of Mo-doped DLC is better than that of substrate. Electrochemical impedance spectroscopy (EIS) studies show that Mo-doped DLC samples behave like an ideal capacitor in Hanks’ solution

  11. Electrochemical studies and growth of apatite on molybdenum doped DLC coatings on titanium alloy β-21S

    Energy Technology Data Exchange (ETDEWEB)

    Anandan, C., E-mail: canandan@nal.res.in; Mohan, L.; Babu, P. Dilli

    2014-03-01

    Highlights: • Titanium alloy β21S was coated with Mo doped DLC. • XRD, XPS and micro Raman show that Mo is present in the form of carbide. • Mo doping facilitates apatite growth on DLC during immersion in Hanks’ solution. • Mo doped DLC sample shows better passivation behavior in Hanks’ solution. - Abstract: Titanium alloy β-21S (Ti–15Mo–3Nb–3Al–0.2Si) was coated with molybdenum doped DLC by Plasma-enhanced chemical vapor deposition and sputtering. XRD, XPS and Raman spectroscopy show that Mo is present in the form of carbide in the coating. XPS of samples immersed in Hanks’ solution shows presence of calcium, phosphorous and oxygen in hydroxide/phosphate form on the substrate and Mo-doped DLC. Potentiodynamic polarization studies show that the corrosion resistance and passivation behavior of Mo-doped DLC is better than that of substrate. Electrochemical impedance spectroscopy (EIS) studies show that Mo-doped DLC samples behave like an ideal capacitor in Hanks’ solution.

  12. Effect of ZDDP concentration on the thermal film formation on steel, hydrogenated non-doped and Si-doped DLC

    Energy Technology Data Exchange (ETDEWEB)

    Akbari, S. [Laboratory for Tribology and Interface Nanotechnology, University of Ljubljana, Ljubljana (Slovenia); Kovač, J. [Jozef Stefan Institute, Jamova 19, 1000 Ljubljana (Slovenia); Kalin, M., E-mail: mitjan.kalin@tint.fs.uni-lj.si [Laboratory for Tribology and Interface Nanotechnology, University of Ljubljana, Ljubljana (Slovenia)

    2016-10-15

    Highlights: • The effect of the ZDDP concentrations onto the steel, H-DLC and Si-DLC surfaces is investigated. • ZDDP film structure on the DLC coatings is different from steel. • Different concentrations of ZDDP do not affect the final chemical structure of the ZDDP film on any of the studied surfaces. • The thickness of the thermal film is linear with the concentration for a given surface. • The reactivity of the ZDDP film is higher on the steel surface than on the DLC coatings. - Abstract: This work focuses on the ZDDP concentration (1, 5 and 20 wt%) to form a ZDDP film on surfaces during static thermal tests at 150 °C. Silicon-doped and hydrogenated DLC coatings, as well as steel as reference, were studied using Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS). The results show that, on the three surfaces, the structure of the ZDDP thermal film consists of identical groups of pyrophosphate and zinc oxide, while the sulphuric groups are dissimilar. On the steel surface, the sulphuric part consists of a mixture of organic sulphide and sulphohydryl groups, but on H-DLC and Si-DLC only organic sulphide groups are found; there are no sulphohydryl groups. Moreover, both ATR-FTIR and XPS show that different concentrations of ZDDP do not affect the final chemical structure of the ZDDP thermal film on any of the studied surfaces. In addition, the XPS results show that the thickness of the thermal film is linear with the concentration for the whole range from 1 to 20 wt%, supporting also its uniform chemical structure. These thicknesses further show that the reactivity of the ZDDP film is higher on the steel surface than on the DLC coatings.

  13. Optical characterization of hydrogen-free CeO2 doped DLC films deposited by unbalanced magnetron sputtering

    International Nuclear Information System (INIS)

    Zhang Zhenyu; Zhou Hongxiu; Guo Dongming; Gao Hang; Kang Renke

    2008-01-01

    A novel kind of hydrogen-free CeO 2 doped diamond-like carbon (DLC) films with thickness of 180-200 nm were deposited on silicon by unbalanced magnetron sputtering. Reduced reflectance and increased lifetime are expected with respect to pure DLC films, making these coatings good candidates as optical protective coatings for IR windows and solar cells. X-ray photoelectron spectroscopy confirms that CeO 2 is formed within the DLC films. Auger electron spectroscopy exhibits that the C, O, and Ce elements distribute uniformly across the film thickness, and C element diffuses into the Si substrate at the interface between the substrate and film. AFM shows that nanoparticles with diameter of around 50 nm are formed on the surface of deposited films, whose surface roughness is in the range of 1.3-2.3 nm. Raman spectra show the CeO 2 doped DLC films are amorphous DLC films, and both the G frequency and relative intensity ratio I D /I G are higher than those of pure DLC films. The photoluminescence of CeO 2 doped DLC films is obviously more intense than that of a pure DLC film, which indicates a promising potential as optical protective films for solar cells and IR window

  14. Tribological properties of Ti-doped DLC coatings under ionic liquids lubricated conditions

    International Nuclear Information System (INIS)

    Feng Xin; Xia Yanqiu

    2012-01-01

    In this paper, titanium doped diamond-like carbon (Ti-DLC) coatings were prepared onto AISI 52100 steel substrates using medium frequency magnetic sputtering process, and were analyzed using the Raman and transmission electron microscope (TEM). Two kinds of 1,3-dialkyl imidazolium ionic liquids (ILs) were synthesized and evaluated as lubricants for Ti-DLC/steel contacts at room temperature, and PFPE as comparison lubricant. The tribological properties of the ILs were investigated using a ball-on-disk type UMT reciprocating friction tester. The results indicated that the ILs have excellent friction-reducing properties, the friction coefficient kept at a relatively stable value of 0.07-0.06, which was reduced approximately by 47% compared with perfluoropolyether (PFPE). The worn surfaces of Ti-DLC coatings were observed and analyzed using a MICROXAM-3D non-contact surface profiler, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The Ti-DLC coatings using ionic liquids lubricating systems are considered as potential lubricating system in vacuum and space moving friction pairs.

  15. Deposition of boron doped DLC films on TiNb and characterization of their mechanical properties and blood compatibility.

    Science.gov (United States)

    Liza, Shahira; Hieda, Junko; Akasaka, Hiroki; Ohtake, Naoto; Tsutsumi, Yusuke; Nagai, Akiko; Hanawa, Takao

    2017-01-01

    Diamond-like carbon (DLC) material is used in blood contacting devices as the surface coating material because of the antithrombogenicity behavior which helps to inhibit platelet adhesion and activation. In this study, DLC films were doped with boron during pulsed plasma chemical vapor deposition (CVD) to improve the blood compatibility. The ratio of boron to carbon (B/C) was varied from 0 to 0.4 in the film by adjusting the flow rate of trimethylboron and acetylene. Tribological tests indicated that boron doping with a low B/C ratio of 0.03 is beneficial for reducing friction (μ = 0.1), lowering hardness and slightly increasing wear rate compared to undoped DLC films. The B/C ratio in the film of 0.03 and 0.4 exhibited highly hydrophilic surface owing to their high wettability and high surface energy. An in vitro platelet adhesion experiment was conducted to compare the blood compatibility of TiNb substrates before and after coating with undoped and boron doped DLC. Films with highly hydrophilic surface enhanced the blood compatibility of TiNb, and the best results were obtained for DLC with the B/C ratio of 0.03. Boron doped DLC films are promising surface coatings for blood contacting devices.

  16. Effect of ZDDP concentration on the thermal film formation on steel, hydrogenated non-doped and Si-doped DLC

    Science.gov (United States)

    Akbari, S.; Kovač, J.; Kalin, M.

    2016-10-01

    This work focuses on the ZDDP concentration (1, 5 and 20 wt%) to form a ZDDP film on surfaces during static thermal tests at 150 °C. Silicon-doped and hydrogenated DLC coatings, as well as steel as reference, were studied using Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS). The results show that, on the three surfaces, the structure of the ZDDP thermal film consists of identical groups of pyrophosphate and zinc oxide, while the sulphuric groups are dissimilar. On the steel surface, the sulphuric part consists of a mixture of organic sulphide and sulphohydryl groups, but on H-DLC and Si-DLC only organic sulphide groups are found; there are no sulphohydryl groups. Moreover, both ATR-FTIR and XPS show that different concentrations of ZDDP do not affect the final chemical structure of the ZDDP thermal film on any of the studied surfaces. In addition, the XPS results show that the thickness of the thermal film is linear with the concentration for the whole range from 1 to 20 wt%, supporting also its uniform chemical structure. These thicknesses further show that the reactivity of the ZDDP film is higher on the steel surface than on the DLC coatings.

  17. Depth profiling of fluorine-doped diamond-like carbon (F-DLC) film: Localized fluorine in the top-most thin layer can enhance the non-thrombogenic properties of F-DLC

    Energy Technology Data Exchange (ETDEWEB)

    Hasebe, Terumitsu [Center for Science of Environment, Resources and Energy, Keio University Faculty of Science and Technology, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522 (Japan); Department of Radiology, Tachikawa Hospital, 4-2-22, Nishiki-cho, Tachikawa, Tokyo 190-8531 (Japan)], E-mail: teru_hasebe@hotmail.com; Nagashima, So [Center for Science of Environment, Resources and Energy, Keio University Faculty of Science and Technology, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522 (Japan); Kamijo, Aki [Department of Transfusion Medicine, the University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Yoshimura, Taichi; Ishimaru, Tetsuya; Yoshimoto, Yukihiro; Yohena, Satoshi; Kodama, Hideyuki; Hotta, Atsushi [Center for Science of Environment, Resources and Energy, Keio University Faculty of Science and Technology, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522 (Japan); Takahashi, Koki [Department of Transfusion Medicine, the University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Suzuki, Tetsuya [Center for Science of Environment, Resources and Energy, Keio University Faculty of Science and Technology, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522 (Japan)

    2007-12-03

    Fluorine-doped diamond-like carbon (F-DLC) has recently drawn a great deal of attention as a more non-thrombogenic coating than conventional DLC for blood-contacting medical devices. We conducted quantitative depth profiling of F-DLC film by X-ray photoelectron spectroscopy (XPS) in order to elucidate the effects of fluorine and fluorine distribution in F-DLC film in connection with the prevention of surface blood adhesion. F-DLC films were prepared on silicon substrates using the radio frequency plasma enhanced chemical vapor deposition method, and the thickness of films was {approx} 50 nm. 50-nm-thick F-DLC film samples were etched at 10-nm thickness intervals using argon plasma, and each surface was examined by XPS. Thereafter, each etched film layer was incubated with platelet-rich plasma isolated from human whole blood, and the platelet-covered area per unit area was evaluated for each surface. XPS spectra showed the localization of doped fluorine in the top-most thin layer of the film. Platelet-covered areas represented progressively larger portions of the surfaces of deeper etched layers, corresponding to the decreasing fluorine content in such sample surfaces. These results indicate that the localized fluorine in the top-most thin layer is one of the key factors in the promotion of the non-thrombogenicity of F-DLC film.

  18. Development, characterization and testing of tungsten doped DLC coatings for dry rotary swaging

    Directory of Open Access Journals (Sweden)

    Hasselbruch Henning

    2015-01-01

    Full Text Available The extensive use of lubricant during rotary swaging is particularly required for a good surface finish of the work piece and the reduction of tool wear. Abandonment of lubricant would improve the ecological process-balance and could also accelerate for further work piece refinements. Also cleaning of the manufactured components becomes obsolete. Thus, a dry machining is highly innovative, consequently new strategies to substitute the lubricant functions become necessary. To encounter the changed tribological conditions due to dry rotary swaging, low friction, tungsten doped, hard DLC coatings and structured surfaces are the most promising approaches. In this work the development of hard coating by means of reactive magnetron sputtering is presented, a promising layer variant is deposited on a set of tools and then tested and investigated in real use.

  19. Silver-doped nanocomposite carbon coatings (Ag-DLC) for biomedical applications - Physiochemical and biological evaluation

    Science.gov (United States)

    Bociaga, Dorota; Komorowski, Piotr; Batory, Damian; Szymanski, Witold; Olejnik, Anna; Jastrzebski, Krzysztof; Jakubowski, Witold

    2015-11-01

    The formation of bacteria biofilm on the surface of medical products is a major clinical issue nowadays. Highly adaptive ability of bacteria to colonize the surface of biomaterials causes a lot of infections. This study evaluates samples of the AISI 316 LVM with special nanocomposite silver-doped (by means of ion implantation) diamond-like carbon (DLC) coating prepared by hybrid RF/MS PACVD (radio frequency/magnetron sputtering plasma assisted chemical vapour deposition) deposition technique in order to improve the physicochemical and biological properties of biomaterials and add new features such as antibacterial properties. The aim of the following work was to evaluate antimicrobial efficacy and biocompatibility of gradient a-C:H/Ti + Ag coatings in relation to the physiochemical properties of the surface and chemical composition of coating. For this purpose, samples were tested in live/dead test using two cell strains: human endothelial cells (Ea.hy926) and osteoblasts-like cells (Saos-2). For testing bactericidal activity of the coatings, an exponential growth phase of Escherichia coli strain DH5α was used as a model microorganism. Surface condition and its physicochemical properties were investigated using SEM, AFM and XPS. Examined coatings showed a uniformity of silver ions distribution in the amorphous DLC matrix, good biocompatibility in contact with mammalian cells and an increased level of bactericidal properties. What is more, considering very good mechanical parameters of these Ag including gradient a-C:H/Ti coatings, they constitute an excellent material for biomedical application in e.g. orthopedics or dentistry.

  20. Deposition and Tribological Properties of Sulfur-Doped DLC Films Deposited by PBII Method

    Directory of Open Access Journals (Sweden)

    Nutthanun Moolsradoo

    2010-01-01

    Full Text Available Sulfur-doped diamond-like carbon films (S-DLC fabricated from C2H2 and SF6 mixtures were used to study the effects of sulfur content and negative pulse bias voltage on the deposition and tribological properties of films prepared by plasma-based ion implantation (PBII. The structure and relative concentration of the films were analyzed by Raman spectroscopy and Auger electron spectroscopy. Hardness and elastic modulus of films were measured by nanoindentation hardness testing. Tribological characteristics of films were performed using a ball-on-disk friction tester. The results indicate that with the increasing sulfur content, the hardness and elastic modulus decrease. Additionally, by changing the negative pulse bias voltage from 0 kV to −5 kV, the hardness and elastic modulus increase, while the friction coefficient and specific wear rate tends to decrease. Moreover, at a negative pulse bias voltage of −5 kV and flow-rate ratio of 1 : 2, there is considerable improvement in friction coefficient of 0.05 under ambient air is due to the formation of a transfer films on the interface. The decrease in the friction coefficient of films doped with 4.9 at.% sulfur is greater under high vacuum (0.03 than under ambient air (>0.1.

  1. Nitrogen doping for adhesion improvement of DLC film deposited on Si substrate by Filtered Cathodic Vacuum Arc (FCVA) technique

    Energy Technology Data Exchange (ETDEWEB)

    Bootkul, D., E-mail: mo_duangkhae@hotmail.com [Department of General Science, Faculty of Science, Srinakharinwirot University, Bangkok 10110 (Thailand); Supsermpol, B.; Saenphinit, N. [Western Digital Company, Ayutthaya 13160 (Thailand); Aramwit, C. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50202 (Thailand); Intarasiri, S., E-mail: saweat@gmail.com [Science and Technology Research Institute, Chiang Mai University, Chiang Mai 50202 (Thailand)

    2014-08-15

    Diamond-like carbon (DLC) films have been used in many applications due to their attractive combination of properties including chemical inertness, corrosion protection, biocompatibility, high hardness, and low wear rates. However, they still have some limitations such as high internal stresses and low toughness which lead to poor adhesion of films. Synthesis of nitrogen-doped DLC (N-DLC) offers the possibility of overcoming these limitations. In this study, DLC films, namely tetrahedral amorphous carbon (ta-C) and nitrogen doped tetrahedral amorphous carbon (ta-C:N) were deposited on single crystalline Si wafer substrates using the Filtered Cathodic Vacuum Arc (FCVA) technique. Film characterizations were carried out by Raman spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), triboindenter tester and nano-scratch tester. Measurement results showed that intentionally doping with nitrogen reduced the carbon sp{sup 3} content and increased the surface roughness in comparison with that of pure ta-C films. The hardness measurement confirmed the Raman and AFM analyses that adding nitrogen in ta-C films decreased the hardness, especially with high nitrogen content. However, the nano-scratch test revealed the increasing of the critical load with nitrogen. This work, then, extended its scope to investigate the properties of double-layer ta-C films which were composed of ta-C:N interlayer of various thickness around 10–30 nm and ta-C top-layer with thickness of around 80 nm. Microstructure characterization demonstrated that a ta-C:N interlayer gradually decreased the sp{sup 3} fraction in the films and increased film roughness whenever the ta-C:N interlayer thickness increased. In this structure, the tribological property in terms of adhesion to the Si substrate was significantly improved by about 20–90%, but the mechanical property in terms of hardness was gradually degraded by about 2–10%, compared to pure ta-C film, when the ta

  2. Preparation of copper doped DLC films by DC PE-CVD method

    International Nuclear Information System (INIS)

    Marton, M.; Vojs, M.; Kotlar, M.; Michniak, P.; Flickyngerova, S.; Vesely, M.; Redhammer, R.

    2012-01-01

    We used PECVD method for deposition of Cu incorporated DLC thin films from CH 4 /Ar gas mixture. The size of nanoparticles varied with changing the deposition conditions in the range of tenth to hundreds of nm. After annealing process, new small Cu particles appeared in the space between the as deposited ones, and all the particles were distributed more homogenous within the films. The resistivity of the DLC films decreased first with adding of copper to 10 to 6·10 3 Ωcm, and second with the annealing process to 4·10 -2 to 3 Ωcm. Raman spectra show the tendency of DLCs to become more graphitic with increasing annealing temperature, which may be one possible contribution to increased conductivity of the annealed Cu-DLC films. (authors)

  3. Microstructure and mechanical properties of Ti/Al co-doped DLC films: Dependence on sputtering current, source gas, and substrate bias

    International Nuclear Information System (INIS)

    Guo, Ting; Kong, Cuicui; Li, Xiaowei; Guo, Peng; Wang, Zhenyu; Wang, Aiying

    2017-01-01

    Highlights: • Ti/Al co-doped diamond-like carbon films were fabricated by a hybrid ion beam method. • Process parameters affected the structure and chemical state of co-doped Ti and Al. • The relation between microstructure and properties was investigated systematically. • The guidance to tailor the Ti/Al-DLC films with high performance was provided. - Abstract: Co-doping two metal elements into diamond-like carbon (DLC) films can reach the desirable combined properties, but the preparation and commercialized application of metal co-doped DLC films with well-defined structural properties are currently hindered by the non-comprehensive understanding of structural evolutions under different process parameters. Here, we fabricated the Ti/Al-DLC films using a unique hybrid ion beam system which enabled the independent control of metal content and carbon structure. The evolutions of microstructure, residual compressive stress and mechanical properties induced by the different process parameters including sputtering currents, C_2H_2 or CH_4 source gases and bias voltages were investigated systematically in order to perform in-depth analysis on the relation between the structure and properties in Ti/Al-DLC films. Results revealed that the variations of process parameters seriously affected the concentration and chemical bond state of co-doped Ti/Al atoms in amorphous carbon matrix or incident energies of C ions, which brought the complicated effect on amorphous carbon structures, accounting for the change of residual compressive stress, hardness and toughness. The present results provide the guidance for suitable, effective parameters selection to tailor the Ti/Al-DLC films with high performance for further applications.

  4. Microstructure and mechanical properties of Ti/Al co-doped DLC films: Dependence on sputtering current, source gas, and substrate bias

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Ting [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China); Kong, Cuicui [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Ningbo University, Ningbo 315201 (China); Li, Xiaowei, E-mail: lixw@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Guo, Peng; Wang, Zhenyu [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Wang, Aiying, E-mail: aywang@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2017-07-15

    Highlights: • Ti/Al co-doped diamond-like carbon films were fabricated by a hybrid ion beam method. • Process parameters affected the structure and chemical state of co-doped Ti and Al. • The relation between microstructure and properties was investigated systematically. • The guidance to tailor the Ti/Al-DLC films with high performance was provided. - Abstract: Co-doping two metal elements into diamond-like carbon (DLC) films can reach the desirable combined properties, but the preparation and commercialized application of metal co-doped DLC films with well-defined structural properties are currently hindered by the non-comprehensive understanding of structural evolutions under different process parameters. Here, we fabricated the Ti/Al-DLC films using a unique hybrid ion beam system which enabled the independent control of metal content and carbon structure. The evolutions of microstructure, residual compressive stress and mechanical properties induced by the different process parameters including sputtering currents, C{sub 2}H{sub 2} or CH{sub 4} source gases and bias voltages were investigated systematically in order to perform in-depth analysis on the relation between the structure and properties in Ti/Al-DLC films. Results revealed that the variations of process parameters seriously affected the concentration and chemical bond state of co-doped Ti/Al atoms in amorphous carbon matrix or incident energies of C ions, which brought the complicated effect on amorphous carbon structures, accounting for the change of residual compressive stress, hardness and toughness. The present results provide the guidance for suitable, effective parameters selection to tailor the Ti/Al-DLC films with high performance for further applications.

  5. Evolution of the mechanical and tribological properties of DLC thin films doped with low-concentration hafnium on 316L steel

    Science.gov (United States)

    Qi, Meng; Xiao, Jianrong; Gong, Chenyang; Jiang, Aihua; Chen, Yong

    2018-01-01

    Low concentrations (stainless steel and silicon (1 0 0) substrates by magnetron sputtering to attain superior mechanical and tribological properties. Ar and CH4 were used as source gases. The microstructure, chemical composition, and morphology of the Hf-DLC thin films in various concentrations were analyzed using x-ray diffraction, Raman spectroscopy, x-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy. Results showed that Hf species transferred from the particulate microstructure to Hf carbide phases, and the surface roughness increased monotonically with increasing Hf concentration. Moreover, the hardness and elastic modulus exhibited high values when the doped Hf concentration was 0.42 at%. Similarly, the tribological behaviors and wear life of Hf-DLC thin films had a low friction coefficient and excellent wear resistance at 0.42 at% Hf concentration. Therefore, 0.42 at% Hf is an optimal doping concentration to improve the mechanical and tribological properties of DLC thin films. Generally, the use of low-concentration Hf doping into DLC thin films is novel, and the present results provide guidance for the selection of suitable and effective concentration to optimize Hf-DLC thin films with superior performance.

  6. Silver-doped nanocomposite carbon coatings (Ag-DLC) for biomedical applications – Physiochemical and biological evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Bociaga, Dorota, E-mail: dorota.bociaga1@gmail.com [Division of Biomedical Engineering and Functional Materials, Lodz University of Technology, Institute of Materials Science and Engineering, 1/15 Stefanowskiego St., 90-924 Lodz (Poland); Komorowski, Piotr [Division of Biophysics, Lodz University of Technology, Institute of Materials Science and Engineering, 1/15 Stefanowskiego St., 90-924 Lodz (Poland); BioNanoPark Laboratories of Lodz Regional Park of Science and Technology, Lodz (Poland); Batory, Damian [Division of Biomedical Engineering and Functional Materials, Lodz University of Technology, Institute of Materials Science and Engineering, 1/15 Stefanowskiego St., 90-924 Lodz (Poland); Szymanski, Witold [Division of Biophysics, Lodz University of Technology, Institute of Materials Science and Engineering, 1/15 Stefanowskiego St., 90-924 Lodz (Poland); Olejnik, Anna; Jastrzebski, Krzysztof [Division of Biomedical Engineering and Functional Materials, Lodz University of Technology, Institute of Materials Science and Engineering, 1/15 Stefanowskiego St., 90-924 Lodz (Poland); Jakubowski, Witold [Division of Biophysics, Lodz University of Technology, Institute of Materials Science and Engineering, 1/15 Stefanowskiego St., 90-924 Lodz (Poland)

    2015-11-15

    Graphical abstract: - Highlights: • The DLC coatings with interlayer improving adhesion were manufactured using the author's method in dual RF/MS PCVD system. • The Ag ions were incorporated into DLC matrix using ion beam implantation method. • The morphology, chemical structure and composition of coatings were examined. • Viability, cytotoxicity of human cells and the formation of bacterial biofilm on the samples surface were evaluated. • <5% of Ag in DLC coating is efficient to make it bactericidal and biocompatible. - Abstract: The formation of bacteria biofilm on the surface of medical products is a major clinical issue nowadays. Highly adaptive ability of bacteria to colonize the surface of biomaterials causes a lot of infections. This study evaluates samples of the AISI 316 LVM with special nanocomposite silver-doped (by means of ion implantation) diamond-like carbon (DLC) coating prepared by hybrid RF/MS PACVD (radio frequency/magnetron sputtering plasma assisted chemical vapour deposition) deposition technique in order to improve the physicochemical and biological properties of biomaterials and add new features such as antibacterial properties. The aim of the following work was to evaluate antimicrobial efficacy and biocompatibility of gradient a-C:H/Ti + Ag coatings in relation to the physiochemical properties of the surface and chemical composition of coating. For this purpose, samples were tested in live/dead test using two cell strains: human endothelial cells (Ea.hy926) and osteoblasts-like cells (Saos-2). For testing bactericidal activity of the coatings, an exponential growth phase of Escherichia coli strain DH5α was used as a model microorganism. Surface condition and its physicochemical properties were investigated using SEM, AFM and XPS. Examined coatings showed a uniformity of silver ions distribution in the amorphous DLC matrix, good biocompatibility in contact with mammalian cells and an increased level of bactericidal

  7. Silver-doped nanocomposite carbon coatings (Ag-DLC) for biomedical applications – Physiochemical and biological evaluation

    International Nuclear Information System (INIS)

    Bociaga, Dorota; Komorowski, Piotr; Batory, Damian; Szymanski, Witold; Olejnik, Anna; Jastrzebski, Krzysztof; Jakubowski, Witold

    2015-01-01

    Graphical abstract: - Highlights: • The DLC coatings with interlayer improving adhesion were manufactured using the author's method in dual RF/MS PCVD system. • The Ag ions were incorporated into DLC matrix using ion beam implantation method. • The morphology, chemical structure and composition of coatings were examined. • Viability, cytotoxicity of human cells and the formation of bacterial biofilm on the samples surface were evaluated. • <5% of Ag in DLC coating is efficient to make it bactericidal and biocompatible. - Abstract: The formation of bacteria biofilm on the surface of medical products is a major clinical issue nowadays. Highly adaptive ability of bacteria to colonize the surface of biomaterials causes a lot of infections. This study evaluates samples of the AISI 316 LVM with special nanocomposite silver-doped (by means of ion implantation) diamond-like carbon (DLC) coating prepared by hybrid RF/MS PACVD (radio frequency/magnetron sputtering plasma assisted chemical vapour deposition) deposition technique in order to improve the physicochemical and biological properties of biomaterials and add new features such as antibacterial properties. The aim of the following work was to evaluate antimicrobial efficacy and biocompatibility of gradient a-C:H/Ti + Ag coatings in relation to the physiochemical properties of the surface and chemical composition of coating. For this purpose, samples were tested in live/dead test using two cell strains: human endothelial cells (Ea.hy926) and osteoblasts-like cells (Saos-2). For testing bactericidal activity of the coatings, an exponential growth phase of Escherichia coli strain DH5α was used as a model microorganism. Surface condition and its physicochemical properties were investigated using SEM, AFM and XPS. Examined coatings showed a uniformity of silver ions distribution in the amorphous DLC matrix, good biocompatibility in contact with mammalian cells and an increased level of bactericidal

  8. Chromium-doped DLC for implants prepared by laser-magnetron deposition

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Miroslav; Kocourek, Tomáš; Zemek, Josef; Mikšovský, Jan; Kubinová, Šárka; Remsa, Jan; Kopeček, Jaromír; Jurek, Karel

    2015-01-01

    Roč. 46, Jan (2015), 381-386 ISSN 0928-4931 R&D Projects: GA ČR(CZ) GA13-33056S; GA MŠk(CZ) LO1309 Institutional support: RVO:68378271 ; RVO:68378041 Keywords : DLC * chromium * hybrid PLD * adhesion * antibacterial properties * toxicity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.420, year: 2015

  9. Adhesive B-doped DLC films on biomedical alloys used for bone

    Indian Academy of Sciences (India)

    The addition of a thin interfacial layer such as Si, Ti, TiN, Mo and Cu/Cr and/or adding additives such as Si, F, N, O, W, V, Co, Mo, Ti or their combinations to the DLC films has been found to increase the adhesion strength substantially. In our study, grade 316L stainless steel and grade 5 titanium alloy (Ti–6Al–4V) were used ...

  10. Transmission photocathodes based on stainless steel mesh and quartz glass coated with N-doped DLC thin films prepared by reactive magnetron sputtering

    Science.gov (United States)

    Balalykin, N. I.; Huran, J.; Nozdrin, M. A.; Feshchenko, A. A.; Kobzev, A. P.; Arbet, J.

    2016-03-01

    The influence was investigated of N-doped diamond-like carbon (DLC) films properties on the quantum efficiency of a prepared transmission photocathode. N-doped DLC thin films were deposited on a silicon substrate, a stainless steel mesh and quartz glass (coated with 5 nm thick Cr adhesion film) by reactive magnetron sputtering using a carbon target and gas mixture Ar, 90%N2+10%H2. The elements' concentration in the films was determined by RBS and ERD. The quantum efficiency was calculated from the measured laser energy and the measured cathode charge. For the study of the vectorial photoelectric effect, the quartz type photocathode was irradiated by intensive laser pulses to form pin-holes in the DLC film. The quantum efficiency (QE), calculated at a laser energy of 0.4 mJ, rose as the nitrogen concentration in the DLC films was increased and rose dramatically after the micron-size perforation in the quartz type photocathodes.

  11. Synthesis of Ti-doped DLC film on SS304 steels by Filtered Cathodic Vacuum Arc (FCVA) technique for tribological improvement

    Science.gov (United States)

    Bootkul, D.; Saenphinit, N.; Supsermpol, B.; Aramwit, C.; Intarasiri, S.

    2014-08-01

    Currently, stainless steels are widely used in various industrial applications due to their excellence in toughness and corrosion resistance. But their resistance to wear needs to be improved for appropriate use in tribological applications. The Filtered Cathodic Vacuum Arc (FCVA) is a superior technique for forming a high-density film structure of amorphous carbon, especially for a tetrahedral amorphous carbon (ta-C) type, because it can produce a plasma of highly energetic ions that can penetrate into a growing coating, resulting in densification of the film. However, this technique tends to generate high internal stress, due to serious accumulation of energy in the film structure that then leads to film delamination. In general, there are numerous solutions that have been used to reduce the internal stress. DLC with various additive elements such as Ti, Cr or W as strong-carbide-forming (SCF) metals is one of the popular methods to provide attractive combinations of properties of wear resistance and film adhesion as well as reducing the internal stress. The present study was focused on investigation of titanium-doped DLC coating on SS304 steel, mainly for adhesion improvement in optimizing for tribological applications. The synthesized films were formed by the FCVA technique at normal substrate temperature. In the experimental set-up, the films were produced by mixing the titanium and carbon ions generated by dual cathode plasma source operating in synchronous pulsed mode. Their compositions were adjusted by varying the relative duration of the pulse length from each cathode. Titanium doping concentration was varied from pure DLC deposition as the control group to titanium and graphite trigger pulses ratios of 1:16, 1:12, 1:10, 1:8 and 1:4, as the Ti-doped DLC group. The results showed that by increasing titanium trigger pulses ratio from 1:16, 1:12, 1:10 and 1:8, respectively, the film adhesion was increased while the wear rate did not change significantly as

  12. The study and fabrication of DLC micropattern on roll mold

    Science.gov (United States)

    Kwon, Young Woo; Lee, Tae Dong; Park, Yeong Min; Cho, Hyun; Kim, Jin Kon; Kim, Tae Gyu

    2015-03-01

    Diamond-like carbon (DLC) coating is becoming a promising protective coating layers due to its superior properties. In this study, instead of protective coating, DLC film was applied as the only component for micropattern then etched with lithography and lift-off process selectively. Furthermore, DLC film has been fabricated on aluminum roll mold. Then UV curing resin was applied to form the pattern on the polyethylene terephthalate (PET) film. The dimension and formation of the DLC micropattern on roll mold were analyzed. Moreover, the Raman spectroscopic of nitrogen-doped DLC film was analyzed.

  13. Covalent modification of boron-doped diamond electrodes with an imidazolium-based ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Wang Mei [Institut de Recherche Interdisciplinaire (IRI, USR 3078), Parc de la Haute Borne, 50 Avenue de Halley, BP 70478, 59658 Villeneuve d' Ascq (France); Institut d' Electronique, de Microelectronique et de Nanotechnologie (IEMN, UMR 8520), Cite Scientifique, Avenue Poincare, BP 60069, 59652 Villeneuve d' Ascq (France); School of Materials Science and Engineering, Shandong University, 19723 Jingshi Road, Jinan, Shandong Province (China); Schneider, Amene [Austrian Centre of Competence for Tribology, Viktor Kaplan Strasse 2, 2700, Wiener Neustadt (Austria); Niedziolka-Joensson, Joanna; Marcon, Lionel [Institut de Recherche Interdisciplinaire (IRI, USR 3078), Parc de la Haute Borne, 50 Avenue de Halley, BP 70478, 59658 Villeneuve d' Ascq (France); Institut d' Electronique, de Microelectronique et de Nanotechnologie (IEMN, UMR 8520), Cite Scientifique, Avenue Poincare, BP 60069, 59652 Villeneuve d' Ascq (France); Ghodbane, Slimane; Steinmueller-Nethl, Doris [Rho-BeSt Coating GmbH, Exlgasse 20a, 6020 Innsbruck (Austria); Li Musen [School of Materials Science and Engineering, Shandong University, 19723 Jingshi Road, Jinan, Shandong Province (China); Boukherroub, Rabah [Institut de Recherche Interdisciplinaire (IRI, USR 3078), Parc de la Haute Borne, 50 Avenue de Halley, BP 70478, 59658 Villeneuve d' Ascq (France); Institut d' Electronique, de Microelectronique et de Nanotechnologie (IEMN, UMR 8520), Cite Scientifique, Avenue Poincare, BP 60069, 59652 Villeneuve d' Ascq (France); Szunerits, Sabine, E-mail: sabine.szunerits@iri.univ-lille1.f [Institut de Recherche Interdisciplinaire (IRI, USR 3078), Parc de la Haute Borne, 50 Avenue de Halley, BP 70478, 59658 Villeneuve d' Ascq (France); Institut d' Electronique, de Microelectronique et de Nanotechnologie (IEMN, UMR 8520), Cite Scientifique, Avenue Poincare, BP 60069, 59652 Villeneuve d' Ascq (France)

    2010-02-01

    An ionic liquid (IL, 1-(methylcarboxylic acid)-3-octylimidazolium-bis (trifluoromethylsulfonyl)imide) was covalently coupled onto a boron-doped diamond (BDD) surface through an esterification reaction. The resulting surface was characterized by X-ray photoelectron spectroscopy, water contact angle and electrochemical measurements. Selective electron transfer towards positively and negatively charged redox species was recorded. While the presence of Fe(CN){sub 6}{sup 4-} could be detected on the IL-modified BDD interface, no surface-immobilized Ru(NH{sub 3}){sub 6}{sup 3+} was recorded. The IL-modified BDD electrode showed in addition changes in surface wettability when immersed into aqueous solution containing different anions.

  14. On the Mott transition and the new metal-insulator transitions in doped covalent and polar crystals

    International Nuclear Information System (INIS)

    Dzhumanov, S.; Begimkulov, U.; Kurbanov, U.T.; Yavidov, B.Y.

    2001-10-01

    The Mott transition and new metal-insulator transitions (MIT's) and their distinctive features in doped covalent semiconductors and polar compounds are studied within the continuum model of extrinsic carrier self-trapping, the Hubbard impurity band model (with on-site Coulomb repulsion and screening effects) and the extrinsic (bi)polaronic band model (with short- and long-range carrier-impurity, impurity-phonon and carrier-phonon interactions and intercarrier correlation) using the appropriate tight-binding approximations and variational methods. We have shown the formation possibility of large-radius localized one- and two-carrier impurity (or defect) states and narrow impurity bands in the band gap and charge transfer gap of these carrier-doped systems. The extrinsic Mott-Hubbard and (bi)polaronic insulating gaps are calculated exactly. The proper criterions for Mott transition, extrinsic excitonic and (bi)polaronic MIT's are obtained. We have demonstrated that the Mott transition occurs in doped covalent semiconductors (i.e. Si and Ge) and some insulators with weak carrier-phonon coupling near the large-radius dopants. While, in doped polar compounds (e.g. oxide high-T c superconductors (HTSC) and related materials) the MIT's are new extrinsic (or intrinsic) (bi)polaronic MIT's. We have found that the anisotropy of the dielectric (or (bi)polaronic) properties of doped cuprate HTSC is responsible for smooth (or continuous) MIT's, stripe formation and suppression of high-T c superconductivity. Various experimental results on in-gap states, bands and MIT's in doped covalent semiconductors, oxide HTSC and related materials are in good agreement with the developed theory of Mott transition and new (bi)polaronic MIT's. (author)

  15. Effect of surface structure and wettability of DLC and N-DLC thin films on adsorption of glycine

    International Nuclear Information System (INIS)

    Ahmed, Mukhtar H.; Byrne, John A.

    2012-01-01

    Diamond-like carbon (DLC) is known to have excellent biocompatibility. Various samples of DLC and nitrogen-doped DLC thin films (N-DLC) were deposited onto silicon substrates using plasma-enhanced chemical vapour deposition (PECVD). Subsequently, the adsorption of amino acid glycine onto the surfaces of the thin films was investigated to elucidate the mechanisms involved in protein adhesion. The physicochemical characteristics of the surfaces, before and after adsorption of glycine, were investigated using Fourier transfer infrared (FTIR), Raman spectroscopy, spectroscopic ellipsometry (SE) and contact angle (θ). The Raman study highlighted decrease slightly in the ID/IG ratio at low levels of N (5.4 at.%), whilst increasing the nitrogen dopant level (>5.4 at.%) resulted in a increase of the ID/IG ratio, and the FTIR band at related to C=N. Following exposure to glycine solutions, the presence of Raman bands at 1727 cm -1 and 1200 cm -1 , and FTIR bands at 1735 cm -1 indicates that the adsorption of glycine onto the surfaces has taken place. These results which obtained from SE and surface free energy, show that low levels of nitrogen doping in DLC enhances the adsorption of the amino acid, while, increased doping led to a reduced adsorption, as compared to undoped DLC. Glycine is bound to the surface of the DLC films via both de-protonated carboxyl and protonated amino groups while, in the case of N-DLC gylcine was bound to the surface via anionic carboxyl groups and the amino group did not interact strongly with the surface. Doping of DLC may allow control of protein adsorption to the surface.

  16. Lithium doping on covalent organic framework-320 for enhancing hydrogen storage at ambient temperature

    International Nuclear Information System (INIS)

    Xia, Liangzhi; Liu, Qing

    2016-01-01

    Density Functional Theory (DFT) combines with grand canonical Monte Carlo (GCMC) simulations are performed to explore the effect of Li doping on the hydrogen storage capability of COF-320. The results show that the interaction energy between the H 2 and the Li-doped COF-320 is about three times higher than that of pristine COF-320. GCMC simulations are employed to study the hydrogen uptake of Li-doped COF-320 at ambient temperature, further confirm that the lithium doping can improve the hydrogen uptake at ambient temperature. Our results demonstrate that Li-doped COFs have good potential in the field of hydrogen storage. - Graphical abstract: Fig. 1. The optimized cluster model used here to represent the COF-320 and possible adsorption sites (A, B, C) for adsorption of metals in the COF-320. The dangling bonds are terminated by H atoms. C, H, and N atoms are shown as gray, white, and blue colors, respectively. Fig. 2. The adsorption isotherm of H 2 in the pristine and Li-doped COF-320 at 298 K. - Highlights: • The binding sites of single and two lithium atoms in COF-320 were studied. • The interaction energy between the H 2 and the Li-doped COF-320 is about three times higher than that of pristine COF-320. • H 2 uptakes on the Li-doped COFs obtain significant improvement at ambient temperature. • Lithium-doping is a successful strategy for improving hydrogen uptake.

  17. Anti-sticking behavior of DLC-coated silicon micro-molds

    International Nuclear Information System (INIS)

    Saha, B; Tor, S B; Liu, E; Khun, N W; Hardt, D E; Chun, J H

    2009-01-01

    Pure carbon- (C), nitrogen- (N) and titanium- (Ti) doped diamond-like carbon (DLC) coatings were deposited on silicon (Si) micro-molds by dc magnetron sputtering deposition to improve the tribological performance of the micro-molds. The coated and uncoated Si molds were used in injection molding for the fabrication of secondary metal-molds, which were used for the replication of micro-fluidic devices. The bonding structure, surface roughness, surface energy, critical load and friction coefficient of the DLC coatings were characterized with micro-Raman spectroscopy, atomic force microscopy (AFM), contact angle, microscratch and ball-on-disc sliding wear tests, respectively. It was observed that the doping conditions had significant effects on Raman peak positions, mechanical and tribological properties of the coatings. The G peak shifted toward a lower position with N and Ti doping. The DLC coating deposited with 1 sccm N 2 flow rate showed the lowest G peak position and the smoothest surface. The surface energies of the pure carbon and Ti-doped DLC coatings were lower than that of the N-doped DLC, which was more significant at a higher N 2 flow rate. In terms of adhesion and friction coefficient, it was observed that the Ti-doped DLC coating had the best performance. Ti incorporated in the DLC coating decreased the residual stress of the coating, which improved the adhesive strength of the coating with the Si substrate

  18. Lithium doping on covalent organic framework-320 for enhancing hydrogen storage at ambient temperature

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Liangzhi, E-mail: 15004110853@163.com; Liu, Qing

    2016-12-15

    Density Functional Theory (DFT) combines with grand canonical Monte Carlo (GCMC) simulations are performed to explore the effect of Li doping on the hydrogen storage capability of COF-320. The results show that the interaction energy between the H{sub 2} and the Li-doped COF-320 is about three times higher than that of pristine COF-320. GCMC simulations are employed to study the hydrogen uptake of Li-doped COF-320 at ambient temperature, further confirm that the lithium doping can improve the hydrogen uptake at ambient temperature. Our results demonstrate that Li-doped COFs have good potential in the field of hydrogen storage. - Graphical abstract: Fig. 1. The optimized cluster model used here to represent the COF-320 and possible adsorption sites (A, B, C) for adsorption of metals in the COF-320. The dangling bonds are terminated by H atoms. C, H, and N atoms are shown as gray, white, and blue colors, respectively. Fig. 2. The adsorption isotherm of H{sub 2} in the pristine and Li-doped COF-320 at 298 K. - Highlights: • The binding sites of single and two lithium atoms in COF-320 were studied. • The interaction energy between the H{sub 2} and the Li-doped COF-320 is about three times higher than that of pristine COF-320. • H{sub 2} uptakes on the Li-doped COFs obtain significant improvement at ambient temperature. • Lithium-doping is a successful strategy for improving hydrogen uptake.

  19. Visible-light sensitization of boron-doped nanocrystalline diamond through non-covalent surface modification

    Czech Academy of Sciences Publication Activity Database

    Krýsová, Hana; Vlčková Živcová, Zuzana; Bartoň, Jan; Petrák, Václav; Nesladek, M.; Cígler, Petr; Kavan, Ladislav

    2015-01-01

    Roč. 17, č. 2 (2015), s. 1165-1172 ISSN 1463-9076 R&D Projects: GA ČR GA13-31783S Institutional support: RVO:61388955 ; RVO:61388963 ; RVO:68378271 Keywords : nanocrystallines * visible-light sensitization * boron-doped diamond Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.449, year: 2015

  20. Properties of titanium-alloyed DLC layers for medical applications

    Science.gov (United States)

    Joska, Ludek; Fojt, Jaroslav; Cvrcek, Ladislav; Brezina, Vitezslav

    2014-01-01

    DLC-type layers offer a good potential for application in medicine, due to their excellent tribological properties, chemical resistance, and bio-inert character. The presented study has verified the possibility of alloying DLC layers with titanium, with coatings containing three levels of titanium concentration prepared. Titanium was present on the surface mainly in the form of oxides. Its increasing concentration led to increased presence of titanium carbide as well. The behavior of the studied systems was stable during exposure in a physiological saline solution. Electrochemical impedance spectra practically did not change with time. Alloying, however, changed the electrochemical behavior of coated systems in a significant way: from inert surface mediating only exchange reactions of the environment in the case of unalloyed DLC layers to a response corresponding rather to a passive surface in the case of alloyed specimens. The effect of DLC layers alloying with titanium was tested by the interaction with a simulated body fluid, during which precipitation of a compound containing calcium and phosphorus - basic components of the bone apatite - occurred on all doped specimens, in contrast to pure DLC. The results of the specimens' surface colonization with cells test proved the positive effect of titanium in the case of specimens with a medium and highest content of this element. PMID:25093457

  1. Characterization of coating probe with Ti-DLC for electrical scanning probe microscope

    International Nuclear Information System (INIS)

    Shia Xiaolei; Guo Liqiu; Bai Yang; Qiao Lijie

    2011-01-01

    In electrical scanning probe microscope (ESPM) applications, the wear and conductivity of the probe are undoubtedly serious concerns since they affect the integrity of the measurements. This study investigates the characterization of Ti doped diamond-like-carbon (DLC) as coating material on a silicon cantilever for ESPM. We deposited a layer of Ti-DLC thin film on the surface of Si cantilever by magnetron sputtering. The morphology and composition of the Ti-DLC films were characterized by scanning electron microscopy and Raman spectroscopy, respectively. We also compared the wear resistance, electric conductivity and scanning image quality of the Ti-DLC-coated probes with those of commercially available conductive probes. The results showed that the electric conductivity and the scanning image quality of the Ti-DLC-coated probes were the same as the commercial conductive probes, while the wear resistance and service life was significantly better.

  2. The MTT assays of bovine retinal pericytes and human microvascular endothelial cells on DLC and Si-DLC-coated TCPS.

    Science.gov (United States)

    Okpalugo, T I T; McKenna, E; Magee, A C; McLaughlin, J; Brown, N M D

    2004-11-01

    MTT (Tetrazolium)-assay suggests that diamond-like carbon (DLC) and silicon-doped DLC (Si-DLC) films obtained under appropriate deposition parameters are not toxic to bovine retinal pericytes, and human microvascular endothelial cells (HMEC). The observed frequency distributions of the optical density (OD) values indicative of cell viability are near Gaussian-normal distribution. One-way ANOVA indicates that at 0.05 levels the population means are not significantly different for the coated and control samples. The observed OD values depend on the cell line (cell growth/metabolic rate), possibly cell cycle stage, the deposition parameters-bias voltage, ion energy, pressure, argon precleaning, and the dopant. For colored thin films like DLC with room temperature photoconductivity and photoelectric effects, it is important to account for the OD contribution from the coating itself. MTT assay, not surprisingly, seems not to be highly sensitive to interfacial cellular interaction resulting from the change in the film's nanostructure, because the tetrazolium metabolism is mainly intracellular and not interfacial. The thin films were synthesized by 13.56 MHz RF-PECVD using argon and acetylene as source gases, with tetramethylsilane (TMS) vapor introduced for silicon doping. This study could be relevant to biomedical application of the films in the eye, peri-vascular, vascular compartments, and for cell-tissue engineering. (c) 2004 Wiley Periodicals, Inc.

  3. MECHANICAL PROPERTIES OF CR-DLC LAYERS PREPARED BY HYBRID LASER TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    Petr Písařík

    2017-06-01

    Full Text Available Diamond like carbon (DLC layers have excellent biological properties for use in medicine for coating implants, but poor adhesion to biomedical alloys. The adhesion can be improved by doping the DLC layer by chromium, as described in this article. Chromium doped diamond like carbon layers (Cr‑DLC were deposited by hybrid deposition system using KrF excimer laser and magnetron sputtering. Carbon and chromium contents were determined by wavelength dispersive X-ray spectroscopy. Mechanical properties were studied by nanoindentation. Hardness and reduced Young's modulus reached 31.2 GPa and 271.5 GPa, respectively. Films adhesion was determined by scratch test and reached 19 N for titanium substrates. Good adhesion to biomedical alloys and high DLC hardness will help to progress in the field of implantology.

  4. Tribological Behaviour of Ti:Ta-DLC Films Under Different Tribo-Test Conditions

    Science.gov (United States)

    Efeoglu, İhsan; Keleş, Ayşenur; Totik, Yaşar; Çiçek, Hikmet; Emine Süküroglu, Ebru

    2018-01-01

    Diamond-like carbon (DLC) films are suitable applicants for cutting tools due to their high hardness, low friction coefficient and wear rate. Doping metals in DLC films have been improved its tribological properties. In this study, titanium and tantalum doped hydrogenated DLC films were deposited by closed-field unbalanced magnetron sputtering system onto M2 high speed steels in Ar/N2/C2H2 atmosphere. The friction and wear properties of Ti:Ta-DLC film were investigated under different tribo-test conditions including in atmospheric pressure, distilled water, commercial oil and Ar atmosphere. The coated specimens were characterized by SEM and X-ray diffraction techniques. The bonding state of C-C (sp3) and C=C (sp2) were obtained with XPS. The tribological properties of Ti:Ta-DLC were investigated with pin-on-disc wear test. Hardness measurements performed by micro-indentation. Our results suggest that Ti:Ta-doped DLC film shows very dense columnar microstructure, high hardness (38.2 GPa) with low CoF (µ≈0.02) and high wear resistance (0.5E-6 mm3/Nm).

  5. Microstructure and properties of duplex (Ti:N)-DLC/MAO coating on magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Wei; Ke, Peiling [Ningbo Key Laboratory of Marine Protection Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Fang, Yong [Sir Run Run Shaw Hospital, School of Medicine, Zhe Jiang University, Zhejiang 310016 (China); Zheng, He [Ningbo Key Laboratory of Marine Protection Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Wang, Aiying, E-mail: aywang@nimte.ac.cn [Ningbo Key Laboratory of Marine Protection Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2013-04-01

    Ti and N co-doped diamond-like carbon ((Ti:N)-DLC) film was deposited on the MAO coated substrate using a hybrid beam deposition system, which consists of a DC magnetron sputtering of Ti target and a linear ion source (LIS) with C{sub 2}H{sub 2} and N{sub 2} precursor gas. The microstructure and properties of the duplex (Ti:N)-DLC/MAO coating were investigated. Results indicate that the (Ti:N)-DLC top film with TiN crystalline phase was formed. Ti and N co-doping resulted in the increasing I{sub D}/I{sub G} ratio. The significant improvement in the wear and corrosion resistance of duplex (Ti:N)-DLC/MAO coating was mainly attributed to the increased binding strength, lubrication characteristics and chemical inertness of (Ti:N)-DLC top film. The superior low-friction and anti-corrosion properties of duplex (Ti:N)-DLC/MAO coating make it a good candidate as protective coating on magnesium alloy.

  6. Doping of alkali, alkaline-earth, and transition metals in covalent-organic frameworks for enhancing CO2 capture by first-principles calculations and molecular simulations.

    Science.gov (United States)

    Lan, Jianhui; Cao, Dapeng; Wang, Wenchuan; Smit, Berend

    2010-07-27

    We use the multiscale simulation approach, which combines the first-principles calculations and grand canonical Monte Carlo simulations, to comprehensively study the doping of a series of alkali (Li, Na, and K), alkaline-earth (Be, Mg, and Ca), and transition (Sc and Ti) metals in nanoporous covalent organic frameworks (COFs), and the effects of the doped metals on CO2 capture. The results indicate that, among all the metals studied, Li, Sc, and Ti can bind with COFs stably, while Be, Mg, and Ca cannot, because the binding of Be, Mg, and Ca with COFs is very weak. Furthermore, Li, Sc, and Ti can improve the uptakes of CO2 in COFs significantly. However, the binding energy of a CO2 molecule with Sc and Ti exceeds the lower limit of chemisorptions and, thus, suffers from the difficulty of desorption. By the comparative studies above, it is found that Li is the best surface modifier of COFs for CO2 capture among all the metals studied. Therefore, we further investigate the uptakes of CO2 in the Li-doped COFs. Our simulation results show that at 298 K and 1 bar, the excess CO2 uptakes of the Li-doped COF-102 and COF-105 reach 409 and 344 mg/g, which are about eight and four times those in the nondoped ones, respectively. As the pressure increases to 40 bar, the CO2 uptakes of the Li-doped COF-102 and COF-105 reach 1349 and 2266 mg/g at 298 K, respectively, which are among the reported highest scores to date. In summary, doping of metals in porous COFs provides an efficient approach for enhancing CO2 capture.

  7. Laser micromachining of sputtered DLC films

    International Nuclear Information System (INIS)

    Fu, Y.Q.; Luo, J.K.; Flewitt, A.J.; Ong, S.E.; Zhang, S.; Milne, W.I.

    2006-01-01

    DLC films with different thicknesses (from 100 nm to 1.9 μm) were deposited using sputtering of graphite target in pure argon atmosphere without substrate heating. Film microstructures (sp 2 /sp 3 ratio) and mechanical properties (modulus, hardness, stress) were characterized as a function of film thickness. A thin layer of aluminum about 60 nm was deposited on the DLC film surface. Laser micromachining of Al/DLC layer was performed to form microcantilever structures, which were released using a reactive ion etching system with SF 6 plasma. Due to the intrinsic stress in DLC films and bimorph Al/DLC structure, the microcantilevers bent up with different curvatures. For DLC film of 100 nm thick, the cantilever even formed microtubes. The relationship between the bimorph beam bending and DLC film properties (such as stress, modulus, etc.) were discussed in details

  8. Tribological properties of duplex MAO/DLC coatings on magnesium alloy using combined microarc oxidation and filtered cathodic arc deposition

    International Nuclear Information System (INIS)

    Liang Jun; Wang Peng; Hu Litian; Hao Jingcheng

    2007-01-01

    The combined microarc oxidation (MAO) and filtered cathode arc deposition process was used to deposit duplex MAO/DLC coating on AM60B magnesium alloy. The microstructure and composition of the resulting duplex coating were analyzed by Raman spectroscopy, X-ray photoelectron spectroscope (XPS) and scanning electron microscope (SEM). The tribological behaviors of the duplex coating were studied by ball-on-disk friction testing. It is found that the Ti-doped DLC thin film could be successfully deposited onto the polished MAO coating. The duplex MAO/DLC coating exhibits a better tribological property than the DLC or MAO monolayer on Mg alloy substrate, owing to the MAO coating served as an intermediate layer provides improved load support for the soft Mg alloy substrate and the DLC top coating exhibits low friction coefficient

  9. Investigation of Physical Properties and Electrochemical Behavior of Nitrogen-Doped Diamond-Like Carbon Thin Films

    Directory of Open Access Journals (Sweden)

    Rattanakorn Saensak

    2014-03-01

    Full Text Available This work reports characterizations of diamond-like carbon (DLC films used as electrodes for electrochemical applications. DLC thin films are prepared on glass slides and silicon substrates by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD using a gas mixture of methane and hydrogen. In addition, the DLC films are doped with nitrogen in order to reduce electrical resistivity. Compared to the undoped DLC films, the electrical resistivity of nitrogen-doped (N-doped DLC films is decreased by three orders of magnitude. Raman spectroscopy and UV/Vis spectroscopy analyses show the structural transformation in N-doped DLC films that causes the reduction of band gap energy. Contact angle measurement at N-doped DLC films indicates increased hydrophobicity. The results obtained from the cyclic voltammetry measurements with Fe(CN63-/Fe(CN64- redox species exhibit the correlation between the physical properties and electrochemical behavior of DLC films.

  10. Antibacterial, mechanical and surface properties of Ag-DLC films prepared by dual PLD for medical applications

    Czech Academy of Sciences Publication Activity Database

    Písařík, Petr; Jelínek, Miroslav; Remsa, Jan; Mikšovský, Jan; Zemek, Josef; Jurek, Karel; Kubinová, Šárka; Lukeš, J.; Šepitka, J.

    2017-01-01

    Roč. 77, Aug (2017), s. 955-962 ISSN 0928-4931 R&D Projects: GA ČR(CZ) GA15-05864S; GA MŠk LO1409 Institutional support: RVO:68378271 Keywords : DLC * silver doped DLC * antibacterial properties * mechanical properties * dual PLD Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.)

  11. Neutron-reflectometry study of alcohol adsorption on various DLC coatings

    Energy Technology Data Exchange (ETDEWEB)

    Kalin, M., E-mail: mitjan.kalin@tint.fs.uni-lj.si [University of Ljubljana, Faculty of Mechanical Engineering, Laboratory for Tribology and Interface Nanotechnology, Bogišićeva 8, 1000 Ljubljana (Slovenia); Simič, R. [University of Ljubljana, Faculty of Mechanical Engineering, Laboratory for Tribology and Interface Nanotechnology, Bogišićeva 8, 1000 Ljubljana (Slovenia); Hirayama, T. [Department of Mechanical Engineering, Doshisha University, 1-3 Miyakodani, Tatara, Kyotanabe, Kyoto 610-0394 (Japan); Geue, T.; Korelis, P. [Paul Scherrer Institute, 5232 Villigen – PSI (Switzerland)

    2014-01-01

    Diamond-like carbon (DLC) coatings are notable for their excellent tribological properties. Our understanding of the lubrication of DLC coatings has improved drastically over the past decade. However, only a few details are known about the properties of the adsorbed layers on DLC, which crucially affect their tribological properties under lubricated conditions. In this work we used neutron reflectometry to determine the thickness and the density of adsorbed layers of alcohol molecules on several different types of DLC coatings, i.e., non-hydrogenated (a-C) and hydrogenated, of which both non-doped (a-C:H) and doped (a-C:H:F and a-C:H:Si) coatings were used. The results showed that a 0.9-nm-thick and relatively dense (≈45%) layer of alcohol adsorbed on the a-C coating. In contrast, no adsorption layer was found on the a-C:H, confirming the important role of hydrogen, which predominantly acts as a dangling-bond passivation source and affects the reactivity and tribochemistry of DLC coatings. The incorporation of F into a DLC coating also did not cause an increase in the adsorption ability with respect to alcohol molecules. On the contrary, the incorporation of Si increased the reactivity of the DLC coating so that a 1.3-nm-thick alcohol layer with a 35% bulk density was detected on the surface. We also discuss the very good agreement of the current results with the surface energy of selected coatings found in these experiments.

  12. XPS and TEM study of W-DLC/DLC double-layered film

    International Nuclear Information System (INIS)

    Takeno, Takanori; Komiyama, Takao; Miki, Hiroyuki; Takagi, Toshiyuki; Aoyama, Takashi

    2009-01-01

    A double-layered film of tungsten-containing diamond-like carbon (W-DLC) and DLC, (W-DLC)/DLC, was investigated. A film of 1.6 μm in thickness was deposited onto silicon substrate. The investigate double-layered coating was deposited by using the combination of PECVD and co-sputtering of tungsten metal target. Structure, interface and chemical bonding state of the investigated film were analyzed by Transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). From the results of the analyses, the structure of double-layered film is that amorphous phase of carbon is continued from DLC to W-DLC and tungsten metal clusters are dispersed in W-DLC layer.

  13. A comparison of the tribological behaviour of steel/steel, steel/DLC and DLC/DLC contact when lubricated with mineral and biodegradable oils

    OpenAIRE

    Kalin, Mitjan; Vižintin, Jože

    2015-01-01

    Diamond-like carbon (DLC) coatings, which can nowadays be applied to many highly loaded mechanical components, sometimes need to operate under lubricated conditions. It is reasonable to expect that in steel/DLC contacts, at least the steel counter body will behave according to conventional lubrication mechanisms and will interact with lubricants and additives in the contact. However, in DLC/DLC contacts, such mechanisms are still unclear. For example, the "inertness" of DLC coatings raises se...

  14. Non-covalent doping of graphitic carbon nitride with ultrathin graphene oxide and molybdenum disulfide nanosheets: an effective binary heterojunction photocatalyst under visible light irradiation.

    Science.gov (United States)

    Hu, S W; Yang, L W; Tian, Y; Wei, X L; Ding, J W; Zhong, J X; Chu, Paul K

    2014-10-01

    A proof of concept integrating binary p-n heterojunctions into a semiconductor hybrid photocatalyst is demonstrated by non-covalent doping of graphite-like carbon nitride (g-C3N4) with ultrathin GO and MoS2 nanosheets using a facile sonochemical method. In this unique ternary hybrid, the layered MoS2 and GO nanosheets with a large surface area enhance light absorption to generate more photoelectrons. On account of the coupling between MoS2 and GO with g-C3N4, the ternary hybrid possesses binary p-n heterojunctions at the g-C3N4/MoS2 and g-C3N4/GO interfaces. The space charge layers created by the p-n heterojunctions not only enhance photogeneration, but also promote charge separation and transfer of electron-hole pairs. In addition, the ultrathin MoS2 and GO with high mobility act as electron mediators to facilitate separation of photogenerated electron-hole pairs at each p-n heterojunction. As a result, the ternary hybrid photocatalyst exhibits improved photoelectrochemical and photocatalytic activity under visible light irradiation compared to other reference materials. The results provide new insights into the large-scale production of semiconductor photocatalysts. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. NANOINDENTATION TEST FOR DLC COATING ANALYSIS

    Directory of Open Access Journals (Sweden)

    Daniel Tischler

    2011-09-01

    Full Text Available In this report the effects of the substrate on the microhardness of Diamond like carbon (DLC thin films were investigated. The DLC coatings were deposited by Radio Frequency Plasma Actived Chemical Vapor Deposition (RF PACVD; 13,56 MHz process on three mechanically polished substrates, which were chosen for comparison; hardened molybdenum high speed steel AISI M2, unhardened tool steel AISI L2 and titanium alloy TiAl6V4. The aim of the present investigation was to determine the influence of substrates on microhardness and other mechanical properties of DLC layer. These properties especially microhardness were studied and compared from nanoindentation load – displacement curves. Results show that the hardness of the substrate is the crucial value for the hardness of the DLC films.

  16. Tribochemistry and Wear Life Improvement in Liquid-Lubricated H-DLC-Coated Bearings

    National Research Council Canada - National Science Library

    Lince, J. R; Kim, H. I; Bertrand, P. A; Eryilmaz, O. L; Erdemir, A

    2007-01-01

    In contrast to typical DLC coatings, hydrogenated DLC (H-DLC) coatings exhibit extremely low friction in vacuum and dry atmospheres, suggesting their potential importance for spacecraft applications...

  17. Tribochemistry of Multiply-Alkylated Cyclopentane Oils on DLC-Coated Thrust Bearings

    National Research Council Canada - National Science Library

    Lince, Jeffrey R; Bertrand, Patricia A

    2007-01-01

    In contrast to typical DLC coatings, hydrogenated DLC (H-DLC) coatings exhibit extremely low friction in vacuum and dry atmospheres, suggesting their potential importance for spacecraft applications...

  18. Novel non-covalent sulfonated multiwalled carbon nanotube from p-toluenesulfonic acid/glucose doped polypyrrole for electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Q.B.; Gao, B.; Hao, L.; Lu, X.J.; Yang, S.D.; Zhang, X.G. [Nanjing Univ. of Aeronautics and Astronautics (China). College of Material Science and Engineering

    2010-07-01

    Polypyrrole (PPy) is considered as one of the most promising electrode materials for electrochemical capacitors due to its environmental stability and fast doping and dedoping capacity. Carbon nanotube (CNT) and PPy hybrids can work synergistically to achieve the advantages of an electric double layer capacitor and faradaic pseudocapacitor. Sulfonation can be used to increase the dispersion of CNTs. In this study, multiwalled CNTs (MWCNTs) were modified with a high -SOH{sub 3}H loading carbonaceous material. Pyrolle monomers were absorbed on the surface of the MWCNT-SO{sub 3}H composite through strong electron and hydrogen bonding interactions between the -SO{sub 3}H group and the amino group of pyrrole. The pyrrole was then in-situ polymerized on the surface of the MWCNTs with the addition of an initiator. The study showed that the specific capacitance loss of the MWCNTs-SO{sub 3}H/PPy was only 3 per cent after 1000 cycles. Results of the study suggested that the composite is a promising electrode material for electrochemical capacitors. 2 refs., 2 figs.

  19. Tribological study of lubricious DLC biocompatible coatings.

    Science.gov (United States)

    Brizuela, M; Garcia-Luis, A; Viviente, J L; Braceras, I; Oñate, J I

    2002-12-01

    DLC (diamond-like carbon) coatings have remarkable tribological properties due mainly to their good frictional behavior. These coatings can be applied in many industrial and biomedical applications, where sliding can generate wear and frictional forces on the components, such as orthopaedic metal implants. This work reports on the development and tribological characterization of functionally gradient titanium alloyed DLC coatings. A PVD-magnetron sputtering technique has been used as the deposition method. The aim of this work was to study the tribological performance of the DLC coating when metal to metal contact (cobalt chromium or titanium alloys) takes place under dry and lubricated test conditions. Prior work by the authors demonstrates that the DLC coating reduced considerably the wear of the ultra-high-molecular-weight polyethylene (UHMWPE). The DLC coating during mechanical testing exhibited a high elastic recovery (65%) compared to the values obtained from Co-Cr-Mo (15%) and Ti-6Al-4V (23%). The coating exhibited an excellent tribo-performance against the Ti-6Al-4V and Co-Cr-Mo alloys, especially under dry conditions presenting a friction value of 0.12 and almost negligible wear. This coating has passed biocompatibility tests for implant devices on tissue/bone contact according to international standards (ISO 10993).

  20. Wettability control by DLC coated nanowire topography

    Science.gov (United States)

    Li, Zihui; Meng, Fanhao; Liu, Xuanyong

    2011-04-01

    Here we have developed a convenient method to fabricate wettability controllable surfaces that can be applied to various nanostructured surfaces with complex shapes for different industrial needs. Diamond-like carbon (DLC) films were synthesized on titanium substrate with a nanowire structured surface using plasma immersion ion implantation and deposition (PIII&D). The nanostructure of the DLC films was characterized by field emission scanning electron microscopy and found to grow in a rippling layer-by-layer manner. Raman spectroscopy was used to investigate the different bonding presented in the DLC films. To determine the wettability of the samples, water contact angles were measured and found to vary in the range of 50°-141°. The results indicated that it was critical to construct a proper surface topography for high hydrophobicity, while suitable ID/IG and sp2/sp3 ratios of the DLC films had a minor contribution. Superhydrophobicity could be achieved by further CF4 implantation on suitably structured DLC films and was attributed to the existence of fluorine. In order to maintain the nanostructure during CF4 implantation, it was favorable to pre-deposit an appropriate carbon content on the nanostructure, as a nanostructure with low carbon content would be deformed during CF4 implantation due to local accumulation of surface charge and the following discharge resulting from the low conductivity.

  1. Covalent Organic

    DEFF Research Database (Denmark)

    Vutti, Surendra

    chemistry of silicon, InAs and GaAs materials, covalentsurface functionalization using organosilanes, liquid-phase, and vapor-phasefunctionalizations, diazo-transfer reaction, CuAAC click chemistry, different types ofbiorthogonal chemistries, SPAAC chemistry, and cellular interactions of chemically...... immobilization of D-amino acid adhesion peptideson azide functionalized silicon, GaAs and InAs materials by using CuAAC-click chemistry.The covalent immobilization of penetration peptide (TAT) on gold nanotips of InAs NWs isalso demonstrated.In chapter four, the covalent immobilization of GFP on silicon wafers......, GaAs wafers andGaAs NWs is demonstrated. Series of Fmoc-Pra-OH, NHS-PEG5-NHS and BCN-NHSfunctionalized silicon surfaces has been prepared, whereby GFP-N3 and GFP-bicyclononyneare immobilized by using CuAAC and SPAAC chemistry. The specific and covalentimmobilization of GFP-N3 on bicyclononyne...

  2. Vessel fluence evaluation for SMART using DLC-23 and DLC-185 data libraries

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyo Youn; Cho, Byung Oh; Joo, Han Gyu [Korea Atomic Energy Research Institute, Taejon (Korea)

    1999-10-01

    In this report, it was performed the vessel fluence evaluation for SMART using nuclear cross-section libraries of DLC-23/CASK and DLC-185/BUGLE-96 and it was compared with the results. It was shown that the maximum neutron fluences for the inner surface of SMART vessel, which has 60 years lifetime and 90% capacity factor, resulted from using DLC-23/CASK and DLC-185/BUGLE-96 are 2.88x10{sup 16} n/cm{sup 2} and 1.98 x10{sup 16} n/cm{sup 2}, respectively. It is concluded that the fast neutron fluence at the reactor pressure vessel of SMART is far less than 1.0x10{sup 20} n/cm{sup 2} which is specified by the requirement of 10 CFR 50.61 and the SMART has the preservation of reactor vessel integrity throughout the reactor lifetime. Also, it was shown that the result using DLC-23/CASK has conservatism of about 30% comparing with the result using DLC-185/BUGLE-96. 15 refs., 7 figs., 13 tabs. (Author)

  3. The cutting properties and wear of the knives with DLC and W-DLC coatings, deposited by PVD methods, applied for wood and wood-based materials machining

    OpenAIRE

    M. Pancielejko; A. Czyżniewski; A. Gilewicz; V. Zavaleyev; W. Szymański

    2012-01-01

    Purpose: Performance of DLC and W-DLC coated woodworking knives was investigated. The results of testing DLC and W-DLC coating properties as well as the results of life-time tests in the form of wear of HSS and HM knives with these coatings is presents.Design/methodology/approach: DLC coating was deposited by MCVA method, and W-DLC coating was deposited by pulsed RMS. Tests of knives coated with DLC and W-DLC as uncoated ones was made by machining: MDF board, pinewood slats and floorboard - u...

  4. Synergistic effect of non-covalent interaction in colloidal nematic liquid crystal doped with magnetic functionalized single-walled carbon nanotubes

    Science.gov (United States)

    Dalir, Nima; Javadian, Soheila

    2018-03-01

    Single-walled carbon nanotubes (SWCNTs), CNT@Fe3O4, and Fe3O4 nanocomposites were doped to eutectic uniaxial nematic liquid crystal (NLC's) (E5CN7) to improve physiochemical properties such as phase transition temperature, activation energy (Ea), dielectric anisotropy, and electro-optical properties. The thermal study of nematic phase shows a decrease in the nematic to isotropic phase transition temperature as CNT is doped. However, higher doping concentration of CNTs leads to the further increase in transition temperature. The anchoring effect or π-π interaction plays a key role in N-I phase transition. The functionalization of SWCNTs with Fe3O4 diminishes the CNT aggregation while the magnetic susceptibility is increased. The functionalized CNT doping to NLC's decrease significantly the phase transition temperature compared to doping of non-functionalized CNTs. Attractive interaction between guest and host molecules by magnetic and geometry effect increased the enthalpy and entropy of phase transition in the SWCNT@Fe3O4 sample compared to non-functionalized CNT doped system. Also, the Ea values are decreased as SWCNT@Fe3O4 is doped to pure E5CN7. The difference of N-I phase transition temperature was observed in Fe3O4 and CNT@Fe3O4 compared to SWCNT doped systems. Finally, dielectric anisotropy was increased in the doped system compared to pure NLC.

  5. DLC-Si protective coatings for polycarbonates

    Directory of Open Access Journals (Sweden)

    Damasceno J.C.

    2003-01-01

    Full Text Available In this work, a-C:H:Si (DLC-Si films were produced onto crystalline silicon and polycarbonate substrates by the rf-PACVD technique from gaseous mixtures of CH4 + SiH4 and C2H2 + SiH4. The effects of self-bias and gas composition upon mechanical and optical properties of the films were investigated. Micro-hardness, residual stress, surface roughness and refractive index measurements were employed for characterization. By incorporating low concentrations of silicon and by exploring the more favorable conditions for the rf-PACVD deposition technique, highly adherent DLC-Si thin films were produced with reduced internal stresses (lower than 1 GPa, high hardness (around 20 GPa and high deposition rates (up to 10 µm/h. Results that show the technological viability of this material for application as protective coatings for polycarbonates are also discussed.

  6. DLC as a Marketing Tool in the Video Game Industry

    OpenAIRE

    Brádlerová, Andrea

    2017-01-01

    This thesis deals with the phenomenon of DLC in the context of marketing communication. DLC or downloadable content expanding the basic game, is a relatively new concept in the video game industry and its role is increasingly important in marketing communication in video games. The main focus of this thesis is to map DLC and analyze its importance in marketing communication and public relations of video game titles of various genres. Theoretical part of the thesis is focused on explaining the...

  7. Preliminary comparative study of laser-prepared DLC and Cr-doped DLC for bacteria adhesion

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Miroslav; Písařík, Petr; Kocourek, Tomáš; Zemek, Josef; Kotzianová, A.; Jurek, Karel; Mikšovský, Jan; Luxbacher, T.

    2014-01-01

    Roč. 116, č. 3 (2014), s. 1437-1443 ISSN 0947-8396 R&D Projects: GA MŠk LD12069 Institutional support: RVO:68378271 Keywords : diamond-like carbon * chromium * contact angle * surface free energy * dual laser deposition * zeta potential Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.704, year: 2014

  8. Preparation of multi-layer film consisting of hydrogen-free DLC and nitrogen-containing DLC for conductive hard coating

    Science.gov (United States)

    Iijima, Yushi; Harigai, Toru; Isono, Ryo; Degai, Satoshi; Tanimoto, Tsuyoshi; Suda, Yoshiyuki; Takikawa, Hirofumi; Yasui, Haruyuki; Kaneko, Satoru; Kunitsugu, Shinsuke; Kamiya, Masao; Taki, Makoto

    2018-01-01

    Conductive hard-coating films have potential application as protective films for contact pins used in the electrical inspection process for integrated circuit chips. In this study, multi-layer diamond-like carbon (DLC) films were prepared as conductive hard-coating films. The multi-layer DLC films consisting of DLC and nitrogen-containing DLC (N-DLC) film were prepared using a T-shape filtered arc deposition method. Periodic DLC/N-DLC four-layer and eight-layer films had the same film thickness by changing the thickness of each layer. In the ball-on-disk test, the N-DLC mono-layer film showed the highest wear resistance; however, in the spherical polishing method, the eight-layer film showed the highest polishing resistance. The wear and polishing resistance and the aggressiveness against an opponent material of the multi-layer DLC films improved by reducing the thickness of a layer. In multi-layer films, the soft N-DLC layer between hard DLC layers is believed to function as a cushion. Thus, the tribological properties of the DLC films were improved by a multi-layered structure. The electrical resistivity of multi-layer DLC films was approximately half that of the DLC mono-layer film. Therefore, the periodic DLC/N-DLC eight-layer film is a good conductive hard-coating film.

  9. Microstructure, mechanical and tribological characterization of CrN/DLC/Cr-DLC multilayer coating with improved adhesive wear resistance

    Science.gov (United States)

    Sui, Xudong; Liu, Jinyu; Zhang, Shuaituo; Yang, Jun; Hao, Junying

    2018-05-01

    Adhesive wear is one of the major reasons for the failure of components during various tribological application, especially for rubbing with viscous materials. This study presents CrN/DLC/Cr-DLC multilayer composite coatings prepared on a plasma enhanced chemical vapor deposition (PECVD) device with the close field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique. SEM, XRD and Raman spectroscopy were used to determine the structure of multilayer coatings. It was found that the multilayer coatings are composed by the alternating CrN and DLC layers. Compared with the single CrN coatings, the friction coefficient of the CrN/DLC/Cr-DLC multilayer coating decreases about more than seven times after sliding a distance of 500 m. This helps to reduce the adhesive wear of multilayer coatings. Compared with the single CrN and DLC coating, the wear rate of the CrN/DLC/Cr-DLC multilayer coating is reduced by an order of magnitude to 7.10 × 10-17 (sliding with AISI 440C) and 2.64 × 10-17 (sliding with TC4) m3/(N m). The improved tribological performance of multilayer coatings mainly attributes to the introduction of lubricant DLC and hard support CrN layers, the enhancement of crack propagation inhibition, and the increment of elastic recovery value We (71.49%) by multilayer design method.

  10. Collapsed tetragonal phase as a strongly covalent and fully nonmagnetic state: Persistent magnetism with interlayer As-As bond formation in Rh-doped Ca0 .8Sr0 .2Fe2As2

    Science.gov (United States)

    Zhao, K.; Glasbrenner, J. K.; Gretarsson, H.; Schmitz, D.; Bednarcik, J.; Etter, M.; Sun, J. P.; Manna, R. S.; Al-Zein, A.; Lafuerza, S.; Scherer, W.; Cheng, J. G.; Gegenwart, P.

    2018-02-01

    A well-known feature of the CaFe2As2 -based superconductors is the pressure-induced collapsed tetragonal phase that is commonly ascribed to the formation of an interlayer As-As bond. Using detailed x-ray scattering and spectroscopy, we find that Rh-doped Ca0.8Sr0.2Fe2As2 does not undergo a first-order phase transition and that local Fe moments persist despite the formation of interlayer As-As bonds. Our density functional theory calculations reveal that the Fe-As bond geometry is critical for stabilizing magnetism and the pressure-induced drop in the c lattice parameter observed in pure CaFe2As2 is mostly due to a constriction within the FeAs planes. The collapsed tetragonal phase emerges when covalent bonding of strongly hybridized Fe 3 d and As 4 p states completely wins out over their exchange splitting. Thus the collapsed tetragonal phase is properly understood as a strong covalent phase that is fully nonmagnetic with the As-As bond forming as a by-product.

  11. Replication performance of Si-N-DLC-coated Si micro-molds in micro-hot-embossing

    International Nuclear Information System (INIS)

    Saha, B; Tor, S B; Liu, E; Khun, N W; Hardt, D E; Chun, J H

    2010-01-01

    Micro-hot-embossing is an emerging technology with great potential to form micro- and nano-scale patterns into polymers with high throughput and low cost. Despite its rapid progress, there are still challenges when this technology is employed, as demolding stress is usually very high due to large friction and adhesive forces induced during the process. Surface forces are dominating parameters in micro- and nano-fabrication technologies because of a high surface-to-volume ratio of products. This work attempted to improve the surface properties of Si micro-molds by means of silicon- and nitrogen-doped diamond-like carbon (Si-N-DLC) coatings deposited by dc magnetron cosputtering on the molds. The bonding structure, surface roughness, surface energy, adhesive strength and tribological behavior of the coated samples were characterized with micro Raman spectroscopy, atomic force microscopy (AFM), contact angle measurement, microscratch test and ball-on-disk sliding tribological test, respectively. It was observed that the doping condition had a great effect on the performance of the coatings. The Si-N-DLC coating deposited with 5 × 10 −6 m 3 min −1 N 2 had lowest surface roughness and energy of about 1.2 nm and 38.2 × 10 −3 N m −1 , respectively, while the coatings deposited with 20 × 10 −6 and 25 × 10 −6 m 3 min −1 N 2 showed lowest friction coefficients. The uncoated and Si-N-DLC-coated Si micro-molds were tested in a micro-hot-embossing process for a comparative study of their replication performance and lifetime. The experimental results showed that the performance of the Si micro-molds was improved by the Si-N-DLC coatings, and well-defined micro-features with a height of about 100 µm were fabricated successfully into cyclic olefin copolymer (COC) sheets using the Si-N-DLC-coated micro-molds.

  12. Surface analysis of DLC coating on cam-tappet system

    OpenAIRE

    FOUVRY, Siegfried; PAGNOUX, Geoffrey; PEIGNEY, Michael; DELATTRE, Benoit; MERMAT-ROLLET, Guillaume

    2013-01-01

    Tribomechanical properties of diamond-like carbon (DLC) coatings make them particularly interesting for numerous applications, like automotive ones. But although DLC coatings show a generally high wear resistance, they sometimes can exhibit severe multiple wear. In this study, a surface analysis of worn coated tappets is performed, leading to a complete coupled wear scenario.

  13. Efficiency and stability of spectral sensitization of boron-doped-diamond electrodes through covalent anchoring of a donor–acceptor organic chromophore (P1)

    Czech Academy of Sciences Publication Activity Database

    Krýsová, Hana; Bartoň, Jan; Petrák, Václav; Jurok, R.; Kuchař, M.; Cígler, Petr; Kavan, Ladislav

    2016-01-01

    Roč. 18, č. 24 (2016), s. 16444-16450 ISSN 1463-9076 R&D Projects: GA ČR GA13-31783S Institutional support: RVO:61388955 ; RVO:61388963 ; RVO:68378271 Keywords : dye-sensitized solar cells * boron-doped diamond * nanoscale Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.123, year: 2016

  14. Osteoblast interaction with DLC-coated Si substrates.

    Science.gov (United States)

    Chai, Feng; Mathis, Nicolas; Blanchemain, Nicolas; Meunier, Cathy; Hildebrand, Hartmut F

    2008-09-01

    Diamond-like carbon (DLC) coating is a convenient means of modifying material surfaces that are sensitive to wear, such as titanium and silica substrates. This work aims to evaluate the osteoblast-like cells' response to DLC-coated Si (Si-DLC), which was treated under different conditions. DLC and deuterated DLC films were deposited by plasma-enhanced chemical vapor deposition to obtain a 200-nm-thick layer on all the samples. Three types of precursor gas were applied for deposition: pure methane (CH(4)), pure deuterated methane (CD(4)) and their half/half mixture. All surface treatments were performed under two different self-bias voltages (V(sb)): -400 and -600V. The modified surfaces were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, Rutherford backscattering spectroscopy, elastic recoil detection analysis, X-ray reflectometry and the sessile-drop method. MC3T3-E1 osteoblasts were cultured on the Si-DLC wafers for 3 and 6 days. Biological tests to measure cell proliferation, cell vitality, cell morphology and cell adhesion were performed. All DLC coatings produced a slightly more hydrophobic state than non-treated Si. Certain types of amorphous DLC coating, such as the surface treated under the V(sb) of -600V in pure methane (600CH(4)) or in pure deuterated methane (600CD(4)), offered a significantly higher cell proliferation rate to Si substrate. Scanning electron microscopy observations confirmed that the optimal cell adhesion behavior, among all the treated surfaces, occurred on the surface of the 600CH(4) and 600CD(4) groups, which showed increased amounts of filopodia and microvilli to enhance cell-environment exchange. In conclusion, DLC coating on Si could produce better surface stability and improved cellular responses.

  15. Development and synthesis nanocompositions DLC coatings with orientation effect

    International Nuclear Information System (INIS)

    Levchenko, V.A.; Novoselova, N.V.; Matveenko, V.N.

    2008-01-01

    On the basis of volume modelling and a detailed experimental research of physical and chemical properties nanocompositions DLC with one-dimensional highly orientationally the carbon structure on interphase border of section with lubricant as models tribological knot, proves typical models of synthesis new nanocompositions the DLC possessing high tribological properties (by high wear resistance, low of a friction, etc.). The influence mechanism orientation properties of a surface of the synthesized coatings on molecular in a boundary lubricant layer is investigated. On basis tribological experimental batch tests nanocompositions the carbon coatings possessing orientation effect, the synthesis mechanism highly orientationally DLC coatings with optimum tribological properties is developed.

  16. Electrochemical properties of N-doped hydrogenated amorphous carbon films fabricated by plasma-enhanced chemical vapor deposition methods

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Yoriko; Furuta, Masahiro; Kuriyama, Koichi; Kuwabara, Ryosuke; Katsuki, Yukiko [Division of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi 753-8512 (Japan); Kondo, Takeshi [Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda 278-8510 (Japan); Fujishima, Akira [Kanagawa Advanced Science and Technology (KAST), 3-2-1, Sakato, Takatsu-ku, Kawasaki-shi, Kanagawa 213-0012 (Japan); Honda, Kensuke, E-mail: khonda@yamaguchi-u.ac.j [Division of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi 753-8512 (Japan)

    2011-01-01

    Nitrogen-doped hydrogenated amorphous carbon thin films (a-C:N:H, N-doped DLC) were synthesized with microwave-assisted plasma-enhanced chemical vapor deposition widely used for DLC coating such as the inner surface of PET bottles. The electrochemical properties of N-doped DLC surfaces that can be useful in the application as an electrochemical sensor were investigated. N-doped DLC was easily fabricated using the vapor of nitrogen contained hydrocarbon as carbon and nitrogen source. A N/C ratio of resulting N-doped DLC films was 0.08 and atomic ratio of sp{sup 3}/sp{sup 2}-bonded carbons was 25/75. The electrical resistivity and optical gap were 0.695 {Omega} cm and 0.38 eV, respectively. N-doped DLC thin film was found to be an ideal polarizable electrode material with physical stability and chemical inertness. The film has a wide working potential range over 3 V, low double-layer capacitance, and high resistance to electrochemically induced corrosion in strong acid media, which were the same level as those for boron-doped diamond (BDD). The charge transfer rates for the inorganic redox species, Fe{sup 2+/3+} and Fe(CN){sub 6}{sup 4-/3-} at N-doped DLC were sufficiently high. The redox reaction of Ce{sup 2+/3+} with standard potential higher than H{sub 2}O/O{sub 2} were observed due to the wider potential window. At N-doped DLC, the change of the kinetics of Fe(CN){sub 6}{sup 3-/4-} by surface oxidation is different from that at BDD. The rate of Fe(CN){sub 6}{sup 3-/4-} was not varied before and after oxidative treatment on N-doped DLC includes sp{sup 2} carbons, which indicates high durability of the electrochemical activity against surface oxidation.

  17. DLC coated textile vascular prostheses tested in sheep

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Miroslav; Kocourek, Tomáš; Podlaha, J.

    2013-01-01

    Roč. 647, JAN (2013), 20-24 ISSN 1022-6680 Institutional support: RVO:68378271 Keywords : DLC * PLD * thin films * vascular prosthesis * pre-clinical study * in vivo Subject RIV: BM - Solid Matter Physics ; Magnetism

  18. Dual laser deposition of Ti: DLC composite for implants

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Miroslav; Zemek, Josef; Kocourek, Tomáš; Remsa, Jan; Mikšovský, Jan; Písařík, Petr; Jurek, Karel; Tolde, Z.; Trávníčková, Martina; Vandrovcová, Marta; Filová, Elena

    2016-01-01

    Roč. 26, č. 10 (2016), 1-8, č. článku 105605. ISSN 1054-660X R&D Projects: GA ČR(CZ) GA15-05864S Institutional support: RVO:68378271 ; RVO:67985823 Keywords : DLC * dopation * dual PLD * implants * Ti:DLC * thin films Subject RIV: BM - Solid Matter Physics ; Magnetism; BO - Biophysics (FGU-C) Impact factor: 1.328, year: 2016

  19. Long-term stable surface modification of DLC coatings

    Directory of Open Access Journals (Sweden)

    Gotzmann Gaby

    2017-09-01

    Full Text Available The use of coatings based on diamond like carbon (DLC for medical applications was established during the last years. Main advantages of these coatings are its high hardness, good wear and friction behavior and its biocompatibility. Using low-energy electron-beam treatment, we addressed the surface modification of DLC coatings. The aim was to generate new biofunctional surface characteristics that are long-term stable.

  20. Evaluation of the tribological properties of DLC for engine applications

    International Nuclear Information System (INIS)

    Lawes, S D A; Fitzpatrick, M E; Hainsworth, S V

    2007-01-01

    Diamond-like carbon (DLC) coatings are used in automotive engines for decreasing friction and increasing durability. There are many variants of DLC films which provide a wide range of mechanical, physical and tribological properties. The films can be extremely hard (>90 GPa), give low coefficients of friction against a number of counterfaces and exhibit low wear coefficients. The films are often considered to be chemically inert. The properties of DLC films depend to a large degree on the relative proportions of graphitically- (sp 2 ) and diamond-like (sp 3 )-bonded carbon but the inclusion of elements such as hydrogen, nitrogen, silicon, tungsten, titanium, fluorine and sulphur can dramatically change their tribological response. Two different types of DLC, a WC/C amorphous hydrogenated DLC (WC/C a-C : H) coating and an amorphous hydrogenated DLC (a-C : H) have been investigated. The mechanical and tribological properties have been evaluated by nanoindentation, scratch and wear testing and friction testing in an instrumented cam-tappet testing rig. The deformation mechanisms and wear processes have been evaluated by scanning electron and atomic force microscopy. The results show that the harder a-C : H film was more wear resistant than the softer WC/C a-C : H film and performed better in the cam-tappet testing rig

  1. Further improvement of mechanical and tribological properties of Cr-doped diamond-like carbon nanocomposite coatings by N codoping

    Science.gov (United States)

    Zou, Changwei; Xie, Wei; Tang, Xiaoshan

    2016-11-01

    In this study, the effects of nitrogen codoping on the microstructure and mechanical properties of Cr-doped diamond-like carbon (DLC) nanocomposite coatings were investigated in detail. Compared with undoped DLC coatings, the Cr-DLC and N/Cr-DLC coatings showed higher root-mean-square (RMS) roughness values. However, from the X-ray photoelectron spectroscopy (XPS) and Raman results, the fraction of sp2 carbon bonds of N/Cr-DLC coatings increased with increasing N content, which indicated the graphitization of the coatings. The hardness and elastic modulus of N/Cr-DLC coatings with 1.8 at. % N were about 26.8 and 218 GPa, respectively. The observed hardness increase with N codoping was attributed to the incorporation of N in the C network along with the formation of CrC(N) nanoparticles, as confirmed from the transmission electron microscopy (TEM) results. The internal stress markedly decreased from 0.93 to 0.32 GPa as the N content increased from 0 to 10.3 at. %. Furthermore, N doping significantly improved the high-temperature dry friction behavior of DLC coatings. The friction coefficient of N/Cr-DLC coatings with 8.0 and 10.3 at. % N was kept at about 0.2 during the overall sliding test at 500 °C. These results showed that appropriate N doping could promote the mechanical and tribological properties of Cr-DLC nanocomposite coatings.

  2. Osteogenic differentiation on DLC-PDMS-h surface.

    Science.gov (United States)

    Soininen, Antti; Kaivosoja, Emilia; Sillat, Tarvo; Virtanen, Sannakaisa; Konttinen, Yrjö T; Tiainen, Veli-Matti

    2014-10-01

    The hypothesis was that anti-fouling diamond-like carbon polydimethylsiloxane hybrid (DLC-PDMS-h) surface impairs early and late cellular adhesion and matrix-cell interactions. The effect of hybrid surface on cellular adhesion and cytoskeletal organization, important for osteogenesis of human mesenchymal stromal cells (hMSC), where therefore compared with plain DLC and titanium (Ti). hMSCs were induced to osteogenesis and followed over time using scanning electron microscopy (SEM), time-of-flight secondary ion mass spectrometry (ToF-SIMS), immunofluorescence staining, quantitative real-time polymerase chain reaction (qRT-PCR), and hydroxyapatite (HA) staining. SEM at 7.5 hours showed that initial adherence and spreading of hMSC was poor on DLC-PDMS-h. At 5 days some hMSC were undergoing condensation and apoptotic fragmentation, whereas cells on DLC and Ti grew well. DAPI-actin-vinculin triple staining disclosed dwarfed cells with poorly organized actin cytoskeleton-focal complex/adhesion-growth substrate attachments on hybrid coating, whereas spread cells, organized microfilament bundles, and focal adhesions were seen on DLC and in particular on Ti. Accordingly, at day one ToF-SIMS mass peaks showed poor protein adhesion to DLC-PDMS-h compared with DLC and Ti. COL1A1, ALP, OP mRNA levels at days 0, 7, 14, 21, and/or 28 and lack of HA deposition at day 28 demonstrated delayed or failed osteogenesis on DLC-PDMS-h. Anti-fouling DLC-PDMS-h is a poor cell adhesion substrate during the early protein adsorption-dependent phase and extracellular matrix-dependent late phase. Accordingly, some hMSCs underwent anoikis-type apoptosis and failed to complete osteogenesis, due to few focal adhesions and poor cell-to-ECM contacts. DLC-PDMS-h seems to be a suitable coating for non-integrating implants/devices designed for temporary use. © 2014 Wiley Periodicals, Inc.

  3. Compositionally modulated multilayer diamond-like carbon coatings with AlTiSi multi-doping by reactive high power impulse magnetron sputtering

    Science.gov (United States)

    Dai, Wei; Gao, Xiang; Liu, Jingmao; Kwon, Se-Hun; Wang, Qimin

    2017-12-01

    Diamond-like carbon (DLC) coatings with AlTiSi multi-doping were prepared by a reactive high power impulse magnetron sputtering with using a gas mixture of Ar and C2H2 as precursor. The composition, microstructure, compressive stress, and mechanical property of the as-deposited DLC coatings were studied systemically by using SEM, XPS, TEM, Raman spectrum, stress-tester, and nanoindentation as a function of the Ar fraction. The results show that the doping concentrations of the Al, Ti and Si atoms increased as the Ar fraction increased. The doped Ti and Si preferred to bond with C while the doped Al mainly existed in oxidation state without bonding with C. As the doping concentrations increased, TiC carbide nanocrystals were formed in the DLC matrix. The microstructure of coatings changed from an amorphous feature dominant AlTiSi-DLC to a carbide nanocomposite AlTiSi-DLC with TiC nanoparticles embedding. In addition, the coatings exhibited the compositionally modulated multilayer consisting of alternate Al-rich layer and Al-poor layer due to the rotation of the substrate holder and the diffusion behavior of the doped Al which tended to separate from C and diffuse towards the DLC matrix surface owing to its weak interactions with C. The periodic Al-rich layer can effectively release the compressive stress of the coatings. On the other hand, the hard TiC nanoparticles were conducive to the hardness of the coatings. Consequently, the DLC coatings with relatively low residual stress and high hardness could be acquired successfully through AlTiSi multi-doping. It is believed that the AlCrSi multi-doping may be a good way for improving the comprehensive properties of the DLC coatings. In addition, we believe that the DLC coatings with Al-rich multilayered structure have a high oxidation resistance, which allows the DLC coatings application in high temperature environment.

  4. Microstructure and high-temperature tribological properties of Si-doped hydrogenated diamond-like carbon films

    Science.gov (United States)

    Zhang, Teng Fei; Wan, Zhi Xin; Ding, Ji Cheng; Zhang, Shihong; Wang, Qi Min; Kim, Kwang Ho

    2018-03-01

    Si-doped DLC films have attracted great attention for use in tribological applications. However, their high-temperature tribological properties remain less investigated, especially in harsh oxidative working conditions. In this study, Si-doped hydrogenated DLC films with various Si content were synthesized and the effects of the addition of Si on the microstructural, mechanical and high-temperature tribological properties of the films were investigated. The results indicate that Si doping leads to an obvious increase in the sp3/sp2 ratio of DLC films, likely due to the silicon atoms preferentially substitute the sp2-hybridized carbon atoms and augment the number of sp3 sites. With Si doping, the mechanical properties, including hardness and adhesion strength, were improved, while the residual stress of the DLC films was reduced. The addition of Si leads to higher thermal and mechanical stability of DLC films because the Si atoms inhibit the graphitization of the films at an elevated temperature. Better high-temperature tribological properties of the Si-DLC films under oxidative conditions were observed, which can be attributed to the enhanced thermal stability and formation of a Si-containing lubricant layer on the surfaces of the wear tracks. The nano-wear resistance of the DLC films was also improved by Si doping.

  5. Controllable Electrochemical Activities by Oxidative Treatment toward Inner-Sphere Redox Systems at N-Doped Hydrogenated Amorphous Carbon Films

    Directory of Open Access Journals (Sweden)

    Yoriko Tanaka

    2012-01-01

    Full Text Available The electrochemical activity of the surface of Nitrogen-doped hydrogenated amorphous carbon thin films (a-CNH, N-doped DLC toward the inner sphere redox species is controllable by modifying the surface termination. At the oxygen plasma treated N-doped DLC surface (O-DLC, the surface functional groups containing carbon doubly bonded to oxygen (C=O, which improves adsorption of polar molecules, were generated. By oxidative treatment, the electron-transfer rate for dopamine (DA positively charged inner-sphere redox analyte could be improved at the N-doped DLC surface. For redox reaction of 2,4-dichlorophenol, which induces an inevitable fouling of the anode surface by forming passivating films, the DLC surfaces exhibited remarkably higher stability and reproducibility of the electrode performance. This is due to the electrochemical decomposition of the passive films without the interference of oxygen evolution by applying higher potential. The N-doped DLC film can offer benefits as the polarizable electrode surface with the higher reactivity and higher stability toward inner-sphere redox species. By making use of these controllable electrochemical reactivity at the O-DLC surface, the selective detection of DA in the mixed solution of DA and uric acid could be achieved.

  6. Investigation of corrosion behavior of nitrogen doped and platinum/ruthenium doped diamond-like carbon thin films in Hank's solution

    International Nuclear Information System (INIS)

    Khun, N.W.; Liu, E.

    2011-01-01

    Undoped (DLC), nitrogen-doped (N-DLC) and platinum/ruthenium doped diamond-like carbon (PtRu-DLC) thin films were deposited on p-Si (100) substrates using a DC magnetron sputtering deposition system. The chemical composition, bonding structure, surface morphology and adhesion strength of the films were characterized using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch test, respectively. The corrosion behavior of the films in a Hank's solution was investigated using potentiodynamic polarization test. The corrosion results revealed that the PtRu-DLC film had the highest corrosion potential among the films used in this study. Highlights: → DLC thin films were deposited on Si substrates via dc magnetron sputtering. → Some DLC films were doped with N and/or Pt/Ru. → The film corrosion behavior was studied in a Hank solution with polarization test. → The PtRu-DLC film showed the highest corrosion potential among the films studied.

  7. Investigation of corrosion behavior of nitrogen doped and platinum/ruthenium doped diamond-like carbon thin films in Hank's solution

    Energy Technology Data Exchange (ETDEWEB)

    Khun, N.W.; Liu, E., E-mail: MEJLiu@ntu.edu.sg

    2011-10-10

    Undoped (DLC), nitrogen-doped (N-DLC) and platinum/ruthenium doped diamond-like carbon (PtRu-DLC) thin films were deposited on p-Si (100) substrates using a DC magnetron sputtering deposition system. The chemical composition, bonding structure, surface morphology and adhesion strength of the films were characterized using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch test, respectively. The corrosion behavior of the films in a Hank's solution was investigated using potentiodynamic polarization test. The corrosion results revealed that the PtRu-DLC film had the highest corrosion potential among the films used in this study. Highlights: {yields} DLC thin films were deposited on Si substrates via dc magnetron sputtering. {yields} Some DLC films were doped with N and/or Pt/Ru. {yields} The film corrosion behavior was studied in a Hank solution with polarization test. {yields} The PtRu-DLC film showed the highest corrosion potential among the films studied.

  8. Effect of various nitrogen flow ratios on the optical properties of (Hf:N-DLC films prepared by reactive magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Meng Qi

    2017-08-01

    Full Text Available Hf and N co-doped diamond-like carbon [(Hf:N-DLC] films were deposited on 316L stainless steel and glass substrates through reactive magnetron sputtering of hafnium and carbon targets at various nitrogen flow ratios (R=N2/[N2+CH4+Ar]. The effects of chemical composition and crystal structure on the optical properties of the (Hf:N-DLC films were studied. The obtained films consist of uniform HfN nanocrystallines embedded into the DLC matrix. The size of the graphite clusters with sp2 bonds (La and the ID/IG ratio increase to 2.47 nm and 3.37, respectively, with increasing R. The optical band gap of the films decreases from 2.01 eV to 1.84 eV with increasing R. This finding is consistent with the trends of structural transformations and could be related to the increase in the density of π-bonds due to nitrogen incorporation. This paper reports the influence of nitrogen flow ratio on the correlation among the chemical composition, crystal structure, and optical properties of (Hf:N-DLC films.

  9. A study of DLC coatings for ironing of stainless steel

    DEFF Research Database (Denmark)

    Sulaiman, Mohd Hafis Bin; Christiansen, Peter; Bay, Niels Oluf

    2017-01-01

    severe lubrication conditions by adopting strip reduction testing to replicate industrial ironing production of deep drawn, stainless steel cans. Three DLC coatings are investigated; multi-layer, double layer and single layer. Experiments revealed that the double layer coating worked successful, i...

  10. Haemocompatibility evaluation of DLC- and SiC-coated surfaces

    Directory of Open Access Journals (Sweden)

    Nurdin N.

    2003-06-01

    Full Text Available Diamond-like carbon (DLC and silicon carbide (SiC coatings are attractive because of low friction coefficient, high hardness, chemical inertness and smooth finish, which they provide to biomedical devices. Silicon wafers (Siwaf and silicone rubber (Sirub plates were coated using plasma-enhanced chemical vapour deposition (PE-CVD techniques. This article describes: 1- the characterization of modified surfaces using attenuated total reflection-Fourier transform infrared spectroscopy (ATR/FTIR and contact angle measurements, 2- the results of three in-vitro haemocompatibility assays. Coated surfaces were compared to uncoated materials and various substrates such as polymethylmethacrylate (PMMA, polyethylene (LDPE, polydimethylsiloxane (PDMS and medical steel (MS. Thrombin generation, blood platelet adhesion and complement convertase activity tests revealed the following classification, from the most to the least heamocompatible surface: Sirub/ DLC-Sirub/ DLC-Siwaf/ LDPE/ PDMS/ SiC-Siwaf/ Siwaf/ PMMA/ MS. The DLC coating surfaces delayed the clotting time, tended to inhibit the platelet and complement convertase activation, whereas SiC-coated silicon wafer can be considered as thrombogenic. This study has taken into account three events of the blood activation: coagulation, platelet activation and inflammation. The response to those events is an indicator of the in vitro haemocompatibility of the different surfaces and it allows us to select biomaterials for further in vivo blood contacting investigations.

  11. A study of DLC coatings for ironing of stainless steel

    DEFF Research Database (Denmark)

    Sulaiman, Mohd Hafis Bin; Christiansen, Peter; Bay, Niels Oluf

    2017-01-01

    Stamping of sheet metal components without lubrication or using minimum amount of hazard free lubricant is a possible solution to diminish health hazards to personnel and environmental impact and to reduce production costs. This paper studies the application of diamond-like coating (DLC) under...

  12. Tribological behavior of W-DLC coated rubber seals

    NARCIS (Netherlands)

    Pei, Y.T.; Bui, X.L.; Zhou, X.B.; Hosson, J.Th.M. De

    2008-01-01

    Tungsten-containing diamond-like carbon (W-DLC) coatings have been deposited on FKM (fluorocarbon) and HNBR (hydrogenated nitrile butadiene) rubbers via unbalanced magnetron reactive sputtering from a WC target in a C2H2/Ar plasma. The surface morphology and fracture cross sections of uncoated and

  13. Erosion–corrosion and corrosion properties of DLC coated low temperature Erosion–corrosion and corrosion properties of DLC coated low temperature

    DEFF Research Database (Denmark)

    Jellesen, Morten Stendahl; Christiansen, Thomas; Hilbert, Lisbeth Rischel

    2009-01-01

    of AISI 316 as substrate for DLC coatings are investigated. Corrosion and erosion–corrosion measurements were carried out on low temperature nitrided stainless steel AISI 316 and on low temperature nitrided stainless steel AISI 316 with a top layer of DLC. The combination of DLC and low temperature...... nitriding dramatically reduces the amount of erosion–corrosion of stainless steel under impingement of particles in a corrosive medium....

  14. Sliding Wear and Fretting Wear of DLC-Based, Functionally Graded Nanocomposite Coatings

    Science.gov (United States)

    Miyoshi, K.; Pohlchuck, B.; Street, Kenneth W.; Zabinski, J. S.; Sanders, J. H.; Voevodin, A. a.; Wu, R. L. C.

    1999-01-01

    Improving the tribological functionality of diamondlike carbon (DLC) films--developing, good wear resistance, low friction, and high load-carrying capacity-was the aim of this investigation. Nanocomposite coatings consisting of an amorphous DLC (a-DLC) top layer and a functionally graded titanium-titanium carbon-diamondlike carbon (Ti-Ti(sub x) C(sub y)-DLC) underlayer were produced on AISI 440C stainless steel substrates by the hybrid technique of magnetron sputtering and pulsed-laser deposition. The resultant DLC films were characterized by Raman spectroscopy, scanning electron microscopy, and surface profilometry. Two types of wear experiment were conducted in this investioation: sliding friction experiments and fretting wear experiments. Unidirectional ball-on-disk sliding friction experiments were conducted to examine the wear behavior of an a-DLC/Ti-Ti(sub x) C(sub y)-DLC-coated AISI 440C stainless steel disk in sliding contact with a 6-mm-diameter AISI 440C stainless steel ball in ultrahigh vacuum, dry nitrogen, and humid air. Although the wear rates for both the coating and ball were low in all three environments, the humid air and dry nitrogen caused mild wear with burnishing, in the a-DLC top layer, and the ultrahigh vacuum caused relatively severe wear with brittle fracture in both the a-DLC top layer and the Ti-Ti(sub x) C(sub y)-DLC underlayer. For reference, amorphous hydrogenated carbon (H-DLC) films produced on a-DLC/Ti-Ti(sub x) C(sub y)-DLC nanocomposite coatings by using an ion beam were also examined in the same manner. The H-DLC films markedly reduced friction even in ultrahigh vacuum without sacrificing wear resistance. The H-DLC films behaved much like the a-DLC/Ti-Ti(sub x) C(sub y)-DLC nanocomposite coating in dry nitrogen and humid air, presenting low friction and low wear. Fretting wear experiments were conducted in humid air (approximately 50% relative humidity) at a frequency of 80 Hz and an amplitude of 75 micron on an a-DLC

  15. Prospects of DLC coating as environment friendly surface treatment process.

    Science.gov (United States)

    Kim, S W; Kim, S G

    2011-06-01

    After first commercialization in 90's, the applications of diamond-like carbon (DLC) have been significantly expanded to tool, automobile parts, machineries and moulds to enhance wear and friction properties. Although DLC has many advantages like high hardness, low friction electrical insulating and chemical stability and has the possible market, its application in the field is still very limited due to the gaps of understanding between end-user and developer of its advantage of costing. Recently, one of the most popular issues in the surface modification is providing the long lasting super-hydrophilic or -hydrophobic properties on the material surface for the outdoor usage. A lot of material loss is caused due to water corrosion which has to do with the flow and contacts of water like fuel cell separator and air conditioner parts. The consequence of development of functional surface based on the hydrophilic or hydrophobic design for the important parts would be really helpful for materials to be cleaner and more energy effective. Here, we first reviewed the DLC technology and then examined the kind of surface modification as well as its merits and disadvantage. We also looked at how we can improve super-hydrophilic and super hydrophobic for the DLC coating layer as well as current status of technology and arts of DLC. In the end, we would like to suggest it as one of the environmental friendly industrial technology. Copyright © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  16. Improvement of corrosion protection property of Mg-alloy by DLC and Si-DLC coatings with PBII technique and multi-target DC-RF magnetron sputtering

    International Nuclear Information System (INIS)

    Masami, Ikeyama; Setsuo, Nakao; Tsutomu, Sonoda; Junho, Choi

    2009-01-01

    Magnesium alloys have been considered as one of the most promising light weight materials with potential applications for automobile and aircraft components. Their poor corrosion resistance, however, has to date prevented wider usage. Diamond-like carbon (DLC) and silicon-incorporated DLC (Si-DLC) coatings are known to provide a high degree of corrosion protection, and hold accordingly promise for enhancing the corrosion resistance of the magnesium alloys. In this work we have studied the effect of coating conditions of DLC coatings as well as Si incorporation into coating on corrosion resistance, deposited onto AZ91 magnesium alloy substrates by plasma based ion implantation (PBII). The influences of a Ti interlayer beneath the DLC, Si-DLC and Ti incorporated DLC (Ti-DLC) coatings fabricated by multi-target direct-current radio-frequency (DC-RF) magnetron sputtering were also examined on both the adhesion strength and corrosion resistance of the materials. We have also examined the effect of the Si content in the Si-DLC coatings made by magnetron sputtering on the alloys' corrosion resistance. The results of potentiodynamic polarization measurements demonstrate that Si-DLC coating deposited by PBII exhibits the highest corrosion resistance in an aqueous 0.05 M NaCl solution. Although Ti layer is helpful in increasing adhesion between DLC coating and AZ91 substrate, it also influences adversely corrosion protection. The ozone treatment of the magnesium alloy's surface before the formation of coatings has been found to improve both adhesion strength and corrosion resistance.

  17. Improvement of corrosion protection property of Mg-alloy by DLC and Si-DLC coatings with PBII technique and multi-target DC-RF magnetron sputtering

    Science.gov (United States)

    Masami, Ikeyama; Setsuo, Nakao; Tsutomu, Sonoda; Junho, Choi

    2009-05-01

    Magnesium alloys have been considered as one of the most promising light weight materials with potential applications for automobile and aircraft components. Their poor corrosion resistance, however, has to date prevented wider usage. Diamond-like carbon (DLC) and silicon-incorporated DLC (Si-DLC) coatings are known to provide a high degree of corrosion protection, and hold accordingly promise for enhancing the corrosion resistance of the magnesium alloys. In this work we have studied the effect of coating conditions of DLC coatings as well as Si incorporation into coating on corrosion resistance, deposited onto AZ91 magnesium alloy substrates by plasma based ion implantation (PBII). The influences of a Ti interlayer beneath the DLC, Si-DLC and Ti incorporated DLC (Ti-DLC) coatings fabricated by multi-target direct-current radio-frequency (DC-RF) magnetron sputtering were also examined on both the adhesion strength and corrosion resistance of the materials. We have also examined the effect of the Si content in the Si-DLC coatings made by magnetron sputtering on the alloys' corrosion resistance. The results of potentiodynamic polarization measurements demonstrate that Si-DLC coating deposited by PBII exhibits the highest corrosion resistance in an aqueous 0.05 M NaCl solution. Although Ti layer is helpful in increasing adhesion between DLC coating and AZ91 substrate, it also influences adversely corrosion protection. The ozone treatment of the magnesium alloy's surface before the formation of coatings has been found to improve both adhesion strength and corrosion resistance.

  18. Elastic nano-structure of diamond-like carbon (DLC)

    International Nuclear Information System (INIS)

    Ogiso, Hisato; Yoshida, Mikiko; Nakano, Shizuka; Yasui, Haruyuki; Awazu, Kaoru

    2006-01-01

    This research discusses the elastic nano-structure of diamond-like carbon (DLC) films. Two DLC film samples deposited by plasma based ion implantation (PBII) were prepared. The plasma generated by microwave (MW) was applied to one sample and the plasma by radio frequency (RF) to the other sample. The samples were evaluated for the elastic property image with nanometer resolution using scanning probe microscopy (SPM). The film surface deposited by RF-PBII was very flat and homogeneous in elastic property. In contrast, the film surface by MW-PBII was more uneven than that by RF-PBII and both the locally hard and the locally soft regions were found at the film surface. The size of the structure in elastic property is several tens nanometer. We conclude that the film probably contains nano-scale diamond phase

  19. Elastic nano-structure of diamond-like carbon (DLC)

    Energy Technology Data Exchange (ETDEWEB)

    Ogiso, Hisato [National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564 (Japan); Yoshida, Mikiko [National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564 (Japan); Nakano, Shizuka [National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564 (Japan); Yasui, Haruyuki [Industrial Research Institute of Ishikawa (IRII), Ro-1, Tomizu-machi, Kanazawa, Ishikawa 920-0233 (Japan); Awazu, Kaoru [Industrial Research Institute of Ishikawa (IRII), Ro-1, Tomizu-machi, Kanazawa, Ishikawa 920-0233 (Japan)

    2006-01-15

    This research discusses the elastic nano-structure of diamond-like carbon (DLC) films. Two DLC film samples deposited by plasma based ion implantation (PBII) were prepared. The plasma generated by microwave (MW) was applied to one sample and the plasma by radio frequency (RF) to the other sample. The samples were evaluated for the elastic property image with nanometer resolution using scanning probe microscopy (SPM). The film surface deposited by RF-PBII was very flat and homogeneous in elastic property. In contrast, the film surface by MW-PBII was more uneven than that by RF-PBII and both the locally hard and the locally soft regions were found at the film surface. The size of the structure in elastic property is several tens nanometer. We conclude that the film probably contains nano-scale diamond phase.

  20. A study of DLC coatings for ironing of stainless steel

    Science.gov (United States)

    Sulaiman, M. H.; Christiansen, P.; Bay, N.

    2017-09-01

    Stamping of sheet metal components without lubrication or using minimum amount of hazard free lubricant is a possible solution to diminish health hazards to personnel and environmental impact and to reduce production costs. This paper studies the application of diamond-like coating (DLC) under severe lubrication conditions by adopting strip reduction testing to replicate industrial ironing production of deep drawn, stainless steel cans. Three DLC coatings are investigated; multi-layer, double layer and single layer. Experiments revealed that the double layer coating worked successful, i.e. with no sign of galling using no lubrication even at elevated tool temperature, while the other two coatings peeled off and resulted in severe galling unless lubrication was applied.

  1. DLC coating of textile blood vessels using PLD

    Czech Academy of Sciences Publication Activity Database

    Kocourek, Tomáš; Jelínek, Miroslav; Vorlíček, Vladimír; Zemek, Josef; Janča, T.; Žížková, V.; Podlaha, J.; Popov, C.

    2008-01-01

    Roč. 93, č. 3 (2008), s. 627-632 ISSN 0947-8396 R&D Projects: GA MPO FI-IM2/068; GA ČR GA202/06/0216 Institutional research plan: CEZ:AV0Z10100522 Keywords : blood vessels * PLD * DLC * sp2 * sp3 Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.884, year: 2008

  2. Tribological Properties of Aluminum Alloy treated by Fine Particle Peening/DLC Hybrid Surface Modification

    Directory of Open Access Journals (Sweden)

    Nanbu H.

    2010-06-01

    Full Text Available In order to improve the adhesiveness of the DLC coating, Fine Particle Peening (FPP treatment was employed as pre-treatment of the DLC coating process. FPP treatment was performed using SiC shot particles, and then AA6061-T6 aluminum alloy was DLC-coated. A SiC-rich layer was formed around the surface of the aluminum alloy by the FPP treatment because small chips of shot particles were embedded into the substrate surface. Reciprocating sliding tests were conducted to measure the friction coefficients. While the DLC coated specimen without FPP treatment showed a sudden increase in friction coefficient at the early stage of the wear cycles, the FPP/DLC hybrid treated specimen maintained a low friction coefficient value during the test period. Further investigation revealed that the tribological properties of the substrate after the DLC coating were improved with an increase in the amount of Si at the surface.

  3. Mechanism analysis of improved DLC films friction behaviors with liquid sulfidation treatment

    International Nuclear Information System (INIS)

    Zeng Qunfeng; Yu Fei; Dong Guangneng; Mao Junhong

    2012-01-01

    Highlights: ► Liquid sulfidation is applied to treat DLC films. ► Sulfur atoms are chemically bonded and the graphitization presented in the treated films. ► The treated films exhibited much lower coefficient of friction than the untreated films under dry friction condition. ► The sulfidation mechanisms are supposed as surface chemical reaction and surface diffusion. ► The presence of sulfur-containing materials and graphitization are beneficial to improve anti-friction behaviors of the treated films. - Abstract: Diamond like carbon (DLC) films were treated by liquid sulfidation to improve their friction behaviors. Friction behaviors of DLC films were experimentally evaluated in ambient air under dry friction using GCr15 steel ball sliding over DLC-coated steel flat in a ball-on-disk tribometer system. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were applied to identify the chemical composition and structure of DLC films. It was found that the content of sp 2 carbon bond increased and G peak shifted to high wave number after sulfidation treatment. The measurement results showed that sulfur atoms were chemically bonded and the graphitization occurred in the treated DLC films. It was indicated that the treated DLC films exhibited much better friction behaviors than the untreated films, especially for DLC films deposited with high nitrogen ratio. In this paper, we proposed the possible sulfidation mechanism of sulfurized DLC films. Sulfidation mechanism is postulated that thiourea reacted with oxygen to form sulfur-containing organic compounds which included CSSC, CSOH and (NH 2 )NH=CSO 2 H and surface diffusion during sulfidation treatment. The anti-friction behaviors of the treated DLC films can be attributed to the production of the compounds containing sulfur on the DLC film surface, the reduce of oxygen content and the presence of graphitization of DLC films.

  4. Regulation of white and brown adipocyte differentiation by RhoGAP DLC1.

    Directory of Open Access Journals (Sweden)

    Choon Kiat Sim

    Full Text Available Adipose tissues constitute an important component of metabolism, the dysfunction of which can cause obesity and type II diabetes. Here we show that differentiation of white and brown adipocytes requires Deleted in Liver Cancer 1 (DLC1, a Rho GTPase Activating Protein (RhoGAP previously studied for its function in liver cancer. We identified Dlc1 as a super-enhancer associated gene in both white and brown adipocytes through analyzing the genome-wide binding profiles of PPARγ, the master regulator of adipogenesis. We further observed that Dlc1 expression increases during differentiation, and knockdown of Dlc1 by siRNA in white adipocytes reduces the formation of lipid droplets and the expression of fat marker genes. Moreover, knockdown of Dlc1 in brown adipocytes reduces expression of brown fat-specific genes and diminishes mitochondrial respiration. Dlc1-/- knockout mouse embryonic fibroblasts show a complete inability to differentiate into adipocytes, but this phenotype can be rescued by inhibitors of Rho-associated kinase (ROCK and filamentous actin (F-actin, suggesting the involvement of Rho pathway in DLC1-regulated adipocyte differentiation. Furthermore, PPARγ binds to the promoter of Dlc1 gene to regulate its expression during both white and brown adipocyte differentiation. These results identify DLC1 as an activator of white and brown adipocyte differentiation, and provide a molecular link between PPARγ and Rho pathways.

  5. Influence of W content on tribological performance of W-doped diamond-like carbon coatings under dry friction and polyalpha olefin lubrication conditions

    International Nuclear Information System (INIS)

    Fu, Zhi-qiang; Wang, Cheng-biao; Zhang, Wei; Wang, Wei; Yue, Wen; Yu, Xiang; Peng, Zhi-jian; Lin, Song-sheng; Dai, Ming-jiang

    2013-01-01

    Highlights: • W-doped DLC coating with various W contents was fabricated. • Friction and wear of DLC coated sample was studied. • The lubricant additive was T307. • The influence of W content on friction under lubrication was unveiled. • The influence of W content on wear under lubrication was studied. - Abstract: The influence on tungsten content on the structure, mechanical properties and tribological performance of W-doped diamond-like carbon (DLC) coatings was studied by X-ray photoelectron spectroscopy, nano-indentation, scratch test, and ball-on-disk friction test. It was found that with increasing W content, the content of WC and free W in the coatings is increased while the content of sp 3 -C in the coatings is decreased. The effect of W content on the hardness and elastic modulus of the coatings is indistinctive, but there exists the highest critical load of scratch test of above 100 N when W content is 3.08 at.%. With the increase of W content, the friction coefficients of W-doped DLC coatings under dry friction conditions are increased while the friction coefficients of W-doped DLC coatings under polyalpha olefin (PAO) lubrication are decreased. With the increase of W content, the wear rates of the DLC-coated samples under dry friction conditions show a minimum value; under pure PAO lubrication, the influence of W content on the wear rates of the DLC-coated samples is indistinctive when the W content is below 10.73 at.% while the wear rates are increased with increasing W content from 10.73 at.% to 24.09 at.%; when lubricated by PAO + thiophosphoric acid amine (T307) salt, the samples coated with the undoped DLC or the W-doped DLC with high W content exhibit low wear rates

  6. Antimicrobial and anti-biofilm properties of polypropylene meshes coated with metal-containing DLC thin films.

    Science.gov (United States)

    Cazalini, Elisa M; Miyakawa, Walter; Teodoro, Guilherme R; Sobrinho, Argemiro S S; Matieli, José E; Massi, Marcos; Koga-Ito, Cristiane Y

    2017-06-01

    A promising strategy to reduce nosocomial infections related to prosthetic meshes is the prevention of microbial colonization. To this aim, prosthetic meshes coated with antimicrobial thin films are proposed. Commercial polypropylene meshes were coated with metal-containing diamond-like carbon (Me-DLC) thin films by the magnetron sputtering technique. Several dissimilar metals (silver, cobalt, indium, tungsten, tin, aluminum, chromium, zinc, manganese, tantalum, and titanium) were tested and compositional analyses of each Me-DLC were performed by Rutherford backscattering spectrometry. Antimicrobial activities of the films against five microbial species (Candida albicans, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis) were also investigated by a modified Kirby-Bauer test. Results showed that films containing silver and cobalt have inhibited the growth of all microbial species. Tungsten-DLC, tin-DLC, aluminum-DLC, zinc-DLC, manganese-DLC, and tantalum-DLC inhibited the growth of some strains, while chromium- and titanium-DLC weakly inhibited the growth of only one tested strain. In-DLC film showed no antimicrobial activity. The effects of tungsten-DLC and cobalt-DLC on Pseudomonas aeruginosa biofilm formation were also assessed. Tungsten-DLC was able to significantly reduce biofilm formation. Overall, the experimental results in the present study have shown new approaches to coating polymeric biomaterials aiming antimicrobial effect.

  7. AlTiN layer effect on mechanical properties of Ti-doped diamond-like carbon composite coatings

    International Nuclear Information System (INIS)

    Pang Xiaolu; Yang Huisheng; Gao Kewei; Wang Yanbin; Volinsky, Alex A.

    2011-01-01

    Ti/Ti-doped diamond-like carbon (DLC) and Ti/AlTiN/Ti-DLC composite coatings were deposited by magnetron sputtering on W18Cr4V high speed steel substrates. The effect of the AlTiN support layer on the properties of these composite coatings was investigated through microstructure and mechanical properties characterization, including hardness, elastic modulus, coefficient of friction and wear properties measured by scanning electron microscopy, Raman spectroscopy, scratch and ball-on-disk friction tests. Ti and AlTiN interlayers have a columnar structure with 50-80 nm grains. The hardness and elastic modulus of Ti/Ti-DLC and Ti/AlTiN/Ti-DLC coatings is 25.9 ± 0.4, 222.2 ± 6.3 GPa and 19.3 ± 1, 205.6 ± 6.7 GPa, respectively. Adhesion of Ti-DLC, Ti/AlTiN/Ti-DLC and AlTiN/Ti-DLC coatings expressed as the critical lateral force is 26.5 N, 38.2 N, and 47.8 N, respectively. Substrate coefficient of friction without coatings is 0.44, and it is 0.1 for Ti/Ti-DLC and Ti/AlTiN/Ti-DLC coatings. Wear resistance of Ti/AlTiN/Ti-DLC composite coatings is much higher than Ti/Ti-DLC coatings based on the wear track width of 169.8 and 73.2 μm, respectively, for the same experimental conditions.

  8. Removal of DLC film on polymeric materials by low temperature atmospheric-pressure plasma jet

    Science.gov (United States)

    Kobayashi, Daichi; Tanaka, Fumiyuki; Kasai, Yoshiyuki; Sahara, Junki; Asai, Tomohiko; Hiratsuka, Masanori; Takatsu, Mikio; Koguchi, Haruhisa

    2017-10-01

    Diamond-like carbon (DLC) thin film has various excellent functions. For example, high hardness, abrasion resistance, biocompatibility, etc. Because of these functionalities, DLC has been applied in various fields. Removal method of DLC has also been developed for purpose of microfabrication, recycling the substrate and so on. Oxygen plasma etching and shot-blast are most common method to remove DLC. However, the residual carbon, high cost, and damage onto the substrate are problems to be solved for further application. In order to solve these problems, removal method using low temperature atmospheric pressure plasma jet has been developed in this work. The removal effect of this method has been demonstrated for DLC on the SUS304 substrate. The principle of this method is considered that oxygen radical generated by plasma oxidize carbon constituting the DLC film and then the film is removed. In this study, in order to widen application range of this method and to understand the mechanism of film removal, plasma irradiation experiment has been attempted on DLC on the substrate with low heat resistance. The DLC was removed successfully without any significant thermal damage on the surface of polymeric material.

  9. Tribological Behaviour of W-DLC against an Aluminium Alloy Subjected to Lubricated Sliding

    Directory of Open Access Journals (Sweden)

    S. Bhowmick

    2015-09-01

    Full Text Available Diamond like carbon (DLC coatings mitigate aluminium adhesion and reduce friction under the ambient conditions but their tribological behaviour under lubricated sliding need to be further investigated. In this study, tribological tests were performed to evaluate the friction and wear characteristics of W-DLC and H-DLC coatings sliding against an aluminium alloy (319 Al under unlubricated (40 % RH and lubricated sliding conditions. For unlubricated sliding, coefficient of friction (COF values of H-DLC and W-DLC were 0.15 and 0.20. A lower COF value of 0.11 was observed when W-DLC was tested using lubricant oil incorporating sulphur while the H-DLC’s COF remained almost unchanged. The mechanisms responsible for the low friction of W-DLC observed during lubricated sliding were revealed by studying the compositions of the coating surfaces and the transfer layers formed on 319 Al. Micro-Raman spectroscopy indicated that the transfer layers formed during lubricated sliding of W-DLC incorporated tungsten disulphide (WS2.

  10. Wear resistance of DLC coating deposited on pretreated AISI 4140 steel

    Energy Technology Data Exchange (ETDEWEB)

    Podgornik, B.; Vizintin, J. [Ljubljana Univ. (Slovenia). Centre of Tribology and Technical Diagnostics; Ronkainen, H.; Holmberg, K. [VTT Manufacturing Technology (Finland). Operational Reliability

    2000-07-01

    In the last few years, the application of nitrided steels as substrates for hard coatings has been increasingly reported. Diamond-like carbon (DLC) coatings, in particular, have attracted significant attention owing to their desirable tribological properties. The aim of the present study was to investigate the possibilities of using hard DLC coatings on softer substrates, such as AISI 4140 steel. (orig.)

  11. Raman Spectroscopy of DLC/a-Si Bilayer Film Prepared by Pulsed Filtered Cathodic Arc

    Directory of Open Access Journals (Sweden)

    C. Srisang

    2012-01-01

    Full Text Available DLC/a-Si bilayer film was deposited on germanium substrate. The a-Si layer, a seed layer, was firstly deposited on the substrate using DC magnetron sputtering and DLC layer was then deposited on the a-Si layer using pulsed filtered cathodic arc method. The bilayer films were deposited with different DLC/a-Si thickness ratios, including 2/2, 2/6, 4/4, 6/2, and 9/6. The effect of DLC/a-Si thickness ratios on the sp3 content of DLC was analyzed by Raman spectroscopy. The results show that a-Si layer has no effect on the structure of DLC film. Furthermore, the upper shift in G wavenumber and the decrease in ID/IG inform that sp3 content of the film is directly proportional to DLC thickness. The plot modified from the three-stage model informed that the structural characteristics of DLC/a-Si bilayer films are located close to the tetrahedral amorphous carbon. This information may be important for analyzing and developing bilayer protective films for future hard disk drive.

  12. [Influence of deposition time on chromatics during nitrogen-doped diamond like carbon coating on pure titanium].

    Science.gov (United States)

    Yin, Lu; Yao, Jiang-wu; Xu, De-wen

    2010-10-01

    The aim of this study was to observed the influence of deposition time on chromatics during nitrogen-doped diamond like carbon coating (N-DLC) on pure titanium by multi impulse are plasma plating machine. Applying multi impulse are plasma plating machine to produce TiN coatings on pure titanium in nitrogen atmosphere, then filming with nitrogen-doped DLC on TiN in methane (10-80 min in every 5 min). The colors of N-DLC were evaluated in the CIE1976 L*a*b* uniform color scale and Mussell notation. The surface morphology of every specimen was analyzed using scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). When changing the time of N-DLC coating deposition, N-DLC surface showed different color. Golden yellow was presented when deposition time was 30 min. SEM showed that crystallization was found in N-DLC coatings, the structure changed from stable to clutter by varying the deposition time. The chromatics of N-DLC coatings on pure titanium could get golden yellow when deposition time was 30 min, then the crystallized structure was stable.

  13. Direct Load Control (DLC) Considering Nodal Interrupted Energy Assessment Rate (NIEAR) in Restructured Power Systems

    DEFF Research Database (Denmark)

    Wu, Qiuwei; Wang, Peng; Goel, Lalit

    2010-01-01

    is used as the bids from the ACL customers, is utilized to determine the direct monetary compensation to the ACL customers. The proposed scheme was investigated for the PoolCo electricity market. The optimal DLC scheme is determined based on the minimum system operating cost which is comprised......A direct load control (DLC) scheme of air conditioning loads (ACL) considering direct monetary compensation to ACL customers for the service interruption caused by the DLC program is proposed in this paper for restructured power systems. The nodal interrupted energy assessment rate (NIEAR), which...... of the system energy cost, the system spinning reserve cost and the compensation cost to the ACL customers. Dynamic programming (DP) was used to obtain the optimal DLC scheme. The IEEE reliability test system (RTS) was studied to illustrate the proposed DLC scheme....

  14. Ultra Low Friction of DLC Coating with Lubricant

    International Nuclear Information System (INIS)

    Kano, M; Yoshida, K

    2010-01-01

    The objective of this study was to find a trigger to make clear a mechanism of the ultra low friction by evaluating the friction property of DLC-DLC combination under lubrication with the simple fluid. The Pin-on-disc reciprocating and rotating sliding tests were conducted to evaluate the friction property. The super low friction property of pure sliding with the ta-C(T) pair coated by the filtered arc deposition process under oleic acid lubrication was found at the mixed lubrication condition. It was thought that the low share strength tribofilm composed of water and acid seemed to be formed on ta-C sliding interface. Additionally, the smooth sliding surface formed on ta-C(T) was seemed to be required to keep this tribofilm. Then, the super low friction was thought to be obtained by this superlubrication condition. Although the accurate and direct experimental data must be required to make clear this super low friction mechanism, the advanced effect obtained by the simple material combination is expected to be applied on the large industrial fields in near future.

  15. Disorder phenomena in covalent semiconductors

    International Nuclear Information System (INIS)

    Popescu, M.A.

    1975-01-01

    The structure of the amorphous semiconductors has been investigated by means of X-ray diffraction and by computer simulation of random network models. Amorphous germanium contains mainly five and six-membered rings of atoms. In glassy state, the ternary compounds A 2 B 4 C 2 5 , such as CdGeAs 2 contain only even rings of atoms (six-membered and eight-membered rings). In the memory glasses of the type A 2 B 4 C 2 5 , such as GeAs 2 Te 7 , the valency state of every element is that from the crystal and important van der Waals forces are effective in the network. No Ge-Ge, Ge-As and As-As bonds are formed. The high pressure forms of the germanium have been simulated by computer. The force constants of the covalent bonds in Ge III and Ge IV differ from those in Ge I. The bond bending force constant decreases rapidly when the density of the crystal increases, a fact which has been imparted to a reduction of the sp 3 hybridization. The compressibility curve of the Ge I has been explained. The effect of the radial and uniaxial deformation on the non-crystalline networks has been studied. The compressibility of the amorphous germanium is by 1.5 per cent greater than that of crystalline germanium. The Poisson coefficient for a-Ge network is 0.233. The structure of the As 2 S 3 glass doped with different amounts of germanium (up to 40 at. per cent) and silver (up to 12 at. per cent) has been investigated. The As 2 S 3 Gesub(x) compositions are constituted from a disordered packing of structural units whose chemical composition and relative proportion in the glass essentially depends on the germanium content. (author)

  16. The stability of DLC film on nitrided CoCrMo alloy in phosphate buffer solution

    International Nuclear Information System (INIS)

    Zhang, T.F.; Liu, B.; Wu, B.J.; Liu, J.; Sun, H.; Leng, Y.X.; Huang, N.

    2014-01-01

    CoCrMo alloy is often used as the material for metal artificial joint, but metal debris and metal ions are the main concern on tissue inflammation or tissue proliferation for metal prosthesis. In this paper, nitrogen ion implantation and diamond like carbon (DLC) film composite treatment was used to reduce the wear and ion release of biomedical CoCrMo substrate. The mechanical properties and stability of N-implanted/DLC composite layer in phosphate buffer solution (PBS) was evaluated to explore the full potential of N-implanted/DLC composite layer as an artificial joint surface modification material. The results showed that the DLC film on N implanted CoCrMo (N-implanted/DLC composite layer) had the higher surface hardness and wear resistance than the DLC film on virgin CoCrMo alloy, which was resulted from the strengthen effect of the N implanted layer on CoCrMo alloy. After 30 days immersion in PBS, the structure of DLC film on virgin CoCrMo or on N implanted CoCrMo had no visible change. But the adhesion and corrosion resistance of DLC on N implanted CoCrMo (N-implanted/DLC composite layer) was weakened due to the dissolution of the N implanted layer after 30 days immersion in PBS. The adhesion reduction of N-implanted/DLC composite layer was adverse for in vivo application in long term. So researcher should be cautious to use N implanted layer as an inter-layer for increasing CoCrMo alloy load carrying capacity in vivo environment.

  17. NEXAFS Study of the Annealing Effect on the Local Structure of FIB-CVD DLC

    International Nuclear Information System (INIS)

    Saikubo, Akihiko; Kato, Yuri; Igaki, Jun-ya; Kanda, Kazuhiro; Matsui, Shinji; Kometani, Reo

    2007-01-01

    Annealing effect on the local structure of diamond like carbon (DLC) formed by focused ion beam-chemical vapor deposition (FIB-CVD) was investigated by the measurement of near edge x-ray absorption fine structure (NEXAFS) and energy dispersive x-ray (EDX) spectra. Carbon K edge absorption NEXAFS spectrum of FIB-CVD DLC was measured in the energy range of 275-320 eV. In order to obtain the information on the location of the gallium in the depth direction, incidence angle dependence of NEXAFS spectrum was measured in the incident angle range from 0 deg. to 60 deg. . The peak intensity corresponding to the resonance transition of 1s→σ* originating from carbon-gallium increased from the FIB-CVD DLC annealed at 200 deg. C to the FIB-CVD DLC annealed at 400 deg. C and decreased from that at 400 deg. C to that at 600 deg. C. Especially, the intensity of this peak remarkably enhanced in the NEXAFS spectrum of the FIB-CVD DLC annealed at 400 deg. C at the incident angle of 60 deg. . On the contrary, the peak intensity corresponding to the resonance transition of 1s→π* originating from carbon double bonding of emission spectrum decreased from the FIB-CVD DLC annealed at 200 deg. C to that at 400 deg. C and increased from that at 400 deg. C to that at 600 deg. C. Gallium concentration in the FIB-CVD DLC decreased from ≅2.2% of the as-deposited FIB-CVD DLC to ≅1.5% of the FIB-CVD DLC annealed at 600 deg. C from the elementary analysis using EDX. Both experimental results indicated that gallium atom departed from FIB-CVD DLC by annealing at the temperature of 600 deg. C

  18. Adsorption mechanisms for fatty acids on DLC and steel studied by AFM and tribological experiments

    International Nuclear Information System (INIS)

    Simič, R.; Kalin, M.

    2013-01-01

    Fatty acids are known to affect the friction and wear of steel contacts via adsorption onto the surface, which is one of the fundamental boundary-lubrication mechanisms. The understanding of the lubrication mechanisms of polar molecules on diamond-like carbon (DLC) is, however, still insufficient. In this work we aimed to find out whether such molecules have a similar effect on DLC coatings as they do on steel. The adsorption of hexadecanoic acid in various concentrations (2–20 mmol/l) on DLC was studied under static conditions using an atomic force microscope (AFM). The amount of surface coverage of the adsorbed fatty-acid molecules was analysed. In addition, tribological tests were performed to correlate the wear and friction behaviours in tribological contacts with the adsorption of molecules on the surface under static conditions. A good correlation between the AFM results and the tribological behaviour was observed. We confirmed that fatty acids can adsorb onto the DLC surfaces and are, therefore, potential boundary-lubrication agents for DLC coatings. The adsorption of the fatty acid onto the DLC surfaces reduces the wear of the coatings, but it is less effective in reducing the friction. Tentative adsorption mechanisms that include an environmental species effect, a temperature effect and a tribochemical effect are proposed for DLC and steel surfaces based on our results and few potential mechanisms found in literature.

  19. Adsorption mechanisms for fatty acids on DLC and steel studied by AFM and tribological experiments

    Energy Technology Data Exchange (ETDEWEB)

    Simič, R.; Kalin, M., E-mail: mitjan.kalin@tint.fs.uni-lj.si

    2013-10-15

    Fatty acids are known to affect the friction and wear of steel contacts via adsorption onto the surface, which is one of the fundamental boundary-lubrication mechanisms. The understanding of the lubrication mechanisms of polar molecules on diamond-like carbon (DLC) is, however, still insufficient. In this work we aimed to find out whether such molecules have a similar effect on DLC coatings as they do on steel. The adsorption of hexadecanoic acid in various concentrations (2–20 mmol/l) on DLC was studied under static conditions using an atomic force microscope (AFM). The amount of surface coverage of the adsorbed fatty-acid molecules was analysed. In addition, tribological tests were performed to correlate the wear and friction behaviours in tribological contacts with the adsorption of molecules on the surface under static conditions. A good correlation between the AFM results and the tribological behaviour was observed. We confirmed that fatty acids can adsorb onto the DLC surfaces and are, therefore, potential boundary-lubrication agents for DLC coatings. The adsorption of the fatty acid onto the DLC surfaces reduces the wear of the coatings, but it is less effective in reducing the friction. Tentative adsorption mechanisms that include an environmental species effect, a temperature effect and a tribochemical effect are proposed for DLC and steel surfaces based on our results and few potential mechanisms found in literature.

  20. Optimization of pulsed DC PACVD parameters: Toward reducing wear rate of the DLC films

    Science.gov (United States)

    Ebrahimi, Mansoureh; Mahboubi, Farzad; Naimi-Jamal, M. Reza

    2016-12-01

    The effect of pulsed direct current (DC) plasma-assisted chemical vapor deposition (PACVD) parameters such as temperature, duty cycle, hydrogen flow, and argon/CH4 flow ratio on the wear behavior and wear durability of the diamond-like carbon (DLC) films was studied by using response surface methodology (RSM). DLC films were deposited on nitrocarburized AISI 4140 steel. Wear rate and wear durability of the DLC films were examined with the pin-on-disk method. Field emission scanning electron microscopy, Raman spectroscopy, and nanoindentation techniques were used for studying wear mechanisms, chemical structure, and hardness of the DLC films. RSM results show that duty cycle is one of the important parameters that affect the wear rate of the DLC samples. The wear rate of the samples deposited with a duty cycle of >75% decreases with an increase in the argon/CH4 ratio. In contrast, for a duty cycle of <65%, the wear rate increases with an increase in the argon/CH4 ratio. The wear durability of the DLC samples increases with an increase in the duty cycle, hydrogen flow, and argon/CH4 flow ratio at the deposition temperature between 85 °C and 110 °C. Oxidation, fatigue, abrasive wear, and graphitization are the wear mechanisms observed on the wear scar of the DLC samples deposited with the optimum deposition conditions.

  1. The study of adhesion and nanomechanical properties of DLC films deposited on tool steels

    International Nuclear Information System (INIS)

    Chen, Kuan-Wei; Lin, Jen-Fin

    2009-01-01

    In this study, thin diamond-like carbon (DLC) films were deposited onto a steel substrate. By using the plasma immersion ion implantation (PIII) technique, a nitrogen layer was formed on the steel surface before depositing the DLC films. This PIII formed nitrogen layer, which acts as the buffer layer, has apparently increased the adhesion between the DLC film and the steel substrate. The microstructures, the nanomechanical properties, and the adhesion of the DLC were investigated by the techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), nanoindentation, and nanoscratch. Results show that the hardness and Young's modulus were significantly improved, up to 2 to 9 times; while the implantation depth and the microstructure of the nitrogen layers vary with nitrogen/hydrogen ratio (N:H = 1:0, 1:1, 1:3). Raman analyses indicate that the I(D)/I(G) ratio increases with the thickness of DLC film. By using the PIII technique in the steel substrate, the adhesion of the DLC film onto the substrate is greatly enhanced, and wear resistance is elevated if the DLC film is sufficiently thick.

  2. Adhesion and differentiation of Saos-2 osteoblast-like cells on chromium-doped diamond-like carbon coatings.

    Science.gov (United States)

    Filova, Elena; Vandrovcova, Marta; Jelinek, Miroslav; Zemek, Josef; Houdkova, Jana; Jan Remsa; Kocourek, Tomas; Stankova, Lubica; Bacakova, Lucie

    2017-01-01

    Diamond-like carbon (DLC) thin films are promising for use in coating orthopaedic, dental and cardiovascular implants. The problem of DLC layers lies in their weak layer adhesion to metal implants. Chromium is used as a dopant for improving the adhesion of DLC films. Cr-DLC layers were prepared by a hybrid technology, using a combination of pulsed laser deposition (PLD) from a graphite target and magnetron sputtering. Depending on the deposition conditions, the concentration of Cr in the DLC layers moved from zero to 10.0 at.%. The effect of DLC layers with 0.0, 0.9, 1.8, 7.3, 7.7 and 10.0 at.% Cr content on the adhesion and osteogenic differentiation of human osteoblast-like Saos-2 cells was assessed in vitro. The DLC samples that contained 7.7 and 10.0 at.% of Cr supported cell spreading on day 1 after seeding. On day three after seeding, the most apparent vinculin-containing focal adhesion plaques were also found on samples with higher concentrations of chromium. On the other hand, the expression of type I collagen and alkaline phosphatase at the mRNA and protein level was the highest on Cr-DLC samples with a lower concentration of Cr (0-1.8 at.%). We can conclude that higher concentrations of chromium supported cell adhesion; however DLC and DLC doped with a lower concentration of chromium supported osteogenic cell differentiation.

  3. Preparation and characterization of DLC/SiO2/Al2O3 nanofiltration ...

    Indian Academy of Sciences (India)

    MS received 12 July 2012; revised 27 September 2012 ... support were deposited using plasma-enhanced chemical vapour deposi- ... the nanofiltration membrane with DLC/SiO2/Al2O3 were observed at various annealing temperatures.

  4. Optimization and characterization of adhesion properties of DLC coatings on different substrates

    International Nuclear Information System (INIS)

    Waseem, B; Alam, S; Irfan, M; Shahid, M; Soomro, B D; Hashim, S; Iqbal, R

    2014-01-01

    The Diamond Like Carbon coatings (DLC) are gaining prime importance in the field of surface engineering especially cutting tools technology. The self lubricating property of these coatings makes them unique among other coatings like TiN, TiAlN, CrN etc. Unlike other coatings, DLC coatings give better surface finish and their self lubrication reduces the wear of a part to large extent. In present work, different substrates were selected to study the wear and adhesion behavior of DLC coatings. The coating was produced by physical Vapor Deposition (PVD) technique and the adhesive properties of DLC coatings were analyzed under ambient conditions using nano Scratch testing. Scanning electron microscope (SEM) was used to observe the scratches and their mechanisms

  5. Optimization and characterization of adhesion properties of DLC coatings on different substrates

    International Nuclear Information System (INIS)

    Waseem, B.; Alam, S.; Irfan, M.; Shahid, M.; Soomro, B. D.; Hashim, S.; Iqbal, R.

    2013-01-01

    The Diamond Like Carbon coatings (DLC) are gaining prime importance in the field of surface engineering especially cutting tools technology. The self lubricating property of these coatings makes them unique among other coatings like TiN, TiAlN, CrN etc. Unlike other coatings, DLC coatings give better surface finish and their self lubrication reduces the wear of a part to large extent. In present work, different substrates were selected to study the wear and adhesion behavior of DLC coatings. The coating was produced by physical Vapor Deposition (PVD) technique and the adhesive properties of DLC coatings were analyzed under ambient conditions using nano Scratch testing. Scanning electron microscope (SEM) was used to observe the scratches and their mechanisms. (author)

  6. Characteristics of diamond – like carbon(DLC film deposited by PACVD process

    Directory of Open Access Journals (Sweden)

    Krzysztof Lukaszkowicz

    2016-10-01

    Full Text Available Diamond – like carbon (DLC film is promising materials for many technical and engineering applications. DLC films are used in many different industries for example: in medicine, in electronics, in optics and the automotive industry. They have excellent tribological properties (low friction coefficient, chemical inertness and high mechanical hardness. This paper provides an analysis of the microstructure, mechanical and tribological properties of DLC films. In the study of the coating used several surface sensitive techniques and methods, i.e. High Resolution Transmission Electron Microscopy (HRTEM, Scanning Electron Microscopy (SEM, Raman spectroscopy and tribological tests like ball-on-disc. HRTEM investigation shows an amorphous character of DLC layer. In sliding dry friction conditions the friction coefficient for the investigated elements is set in the range between 0.02-0.03. The investigated coating reveals high wear resistance. The coating demonstrated a good adhesion to the substrate.

  7. Transparent Si–DLC coatings on metals with high repetition bi-polar pulses of a PBII system

    Energy Technology Data Exchange (ETDEWEB)

    Ikeyama, Masami, E-mail: ikeyama3@aist.go.jp; Sonoda, Tsutomu, E-mail: tsutomu.sonoda@aist.go.jp

    2013-07-15

    Diamond-like carbon (DLC) is widely used because of its good properties. However, the color of DLC is usually dark brown or black. Recently, we have made fairly transparent Si contained DLC (Si–DLC) coatings in visible light region. The fairly transparent Si–DLC was made by using our original bi-polar pulse type plasma based ion implantation (PBII) system, with recently introduced high slew rate pulse power supply. The colors of metal sample surface were uniformly changed as subdued red, yellow, subdued green and subdued blue or violet, with the change of Si–DLC coating’s thickness. The colors come from the interference between reflected lights at the surface of the Si–DLC coatings and the surface of the metal samples. The colors were also changed with the angle of glancing. Estimated refractive indexes show well agreements among almost all Si–DLC coatings, instead of the differences of coating conditions. Generally, the longer coating time or slower coating process makes the higher refractive index in near infrared region. Estimated band gap of a Si–DLC coating was about 1.5 eV. The developed Si–DLC coatings must be useful as not only protective but also decorative coatings.

  8. Fluorine and boron co-doped diamond-like carbon films deposited by pulsed glow discharge plasma immersion ion processing

    CERN Document Server

    He, X M; Peters, A M; Taylor, B; Nastasi, M

    2002-01-01

    Fluorine (F) and boron (B) co-doped diamond-like carbon (FB-DLC) films were prepared on different substrates by the plasma immersion ion processing (PIIP) technique. A pulse glow discharge plasma was used for the PIIP deposition and was produced at a pressure of 1.33 Pa from acetylene (C sub 2 H sub 2), diborane (B sub 2 H sub 6), and hexafluoroethane (C sub 2 F sub 6) gas. Films of FB-DLC were deposited with different chemical compositions by varying the flow ratios of the C sub 2 H sub 2 , B sub 2 H sub 6 , and C sub 2 F sub 6 source gases. The incorporation of B sub 2 H sub 6 and C sub 2 F sub 6 into PIIP deposited DLC resulted in the formation of F-C and B-C hybridized bonding structures. The levels of the F and B concentrations effected the chemical bonding and the physical properties as was evident from the changes observed in density, hardness, stress, friction coefficient, and contact angle of water on films. Compared to B-doped or F-doped DLC films, the F and B co-doping of DLC during PIIP deposition...

  9. Mechanical properties, chemical analysis and evaluation of antimicrobial response of Si-DLC coatings fabricated on AISI 316 LVM substrate by a multi-target DC-RF magnetron sputtering method for potential biomedical applications

    Science.gov (United States)

    Bociaga, Dorota; Sobczyk-Guzenda, Anna; Szymanski, Witold; Jedrzejczak, Anna; Jastrzebska, Aleksandra; Olejnik, Anna; Jastrzebski, Krzysztof

    2017-09-01

    In this study silicon doped diamond-like carbon (Si-DLC) coatings were synthesized on two substrates: silicon and AISI 316LVM stainless steel using a multi-target DC-RF magnetron sputtering method. The Si content in the films ranged between 4 and 16 at.%, and was controlled by the electrical power applied in RF regime to Si cathode target. The character of the chemical bonds was revealed by FTIR analysis. With the addition of silicon the hydroxyl absorption (band in the range of 3200-3600 cm-1) increased what suggests more hydrophilic character of the coating. There were also observed significant changes in bonding of Si atoms. For low content of dopant, Si-O-Si bond system is predominant, while for the highest content of silicon there is an evidence of the shift to Si-C bonds in close proximity to methyl groups. The Raman spectroscopy revealed that the G peak position is shifted to a lower wavenumber and the ID/IG ratio decreased with increasing Si content, which indicates an increase in the C-sp3 content. Regardless of the coatings' composition, the improvement of hardness in comparison to pure substrate material (AISI 316 LVM) was observed. Although the reduction of the level of hardness from the level of 10.8 GPa for pure DLC to about 9.4 GPa for the silicon doped coatings was observed, the concomitant improvement of films adhesion with higher amount of Si was revealed. Although incorporation of the dopant to DLC coatings increases the number of E. coli cells which adhered to the examined surfaces, the microbial colonisation remains on the level of substrate material. The presented results prove the potential of Si-DLC coatings in biomedical applications from the point of view of their mechanical properties.

  10. Significance of genetic variants in DLC1 and their association with hepatocellular carcinoma

    Science.gov (United States)

    XIE, CHENG-RONG; SUN, HONG-GUANG; SUN, YU; ZHAO, WEN-XIU; ZHANG, SHENG; WANG, XIAO-MIN; YIN, ZHEN-YU

    2015-01-01

    DLC1 has been shown to be downregulated or absent in hepatocellular carcinoma (HCC) and is associated with tumorigenesis and development. However, only a small number of studies have focused on genetic variations of DLC1. The present study performed exon sequencing for the DLC1 gene in HCC tissue samples from 105 patients to identify functional genetic variation of DLC1 and its association with HCC susceptibility, clinicopathological features and prognosis. A novel missense mutation and four non-synonymous single nucleotide polymorphisms (SNPs; rs3816748, rs11203495, rs3816747 and rs532841) were identified. A significant correlation of rs3816747 polymorphisms with HCC susceptibility was identified. Compared to individuals with the GG genotype of rs3816747, those with the GA (odds ratio (OR)=0.486; P=0.037) or GA+AA genotype (OR=0.51; P=0.039) were associated with a significantly decreased HCC risk. Furthermore, patients with the GC+CC genotype of rs3816748, the TC+CC genotype of rs11203495 or the GA+AA genotype of rs3816747 had small-sized tumors compared with those carrying the wild-type genotype. No significant association of DLC1 SNPs with the patients' prognosis was found. These results indicated that genetic variations in the DLC1 gene may confer a risk for HCC. PMID:26095787

  11. The Barrier Properties of PET Coated DLC Film Deposited by Microwave Surface-Wave PECVD

    Science.gov (United States)

    Yin, Lianhua; Chen, Qiang

    2017-12-01

    In this paper we report the investigation of diamond-like carbon (DLC) deposited by microwave surface-wave plasma enhanced chemical vapor deposition (PECVD) on the polyethylene terephthalate (PET) web for the purpose of the barrier property improvement. In order to characterize the properties of DLC coatings, we used several substrates, silicon wafer, glass, and PET web and KBr tablet. The deposition rate was obtained by surface profiler based on the DLC deposited on glass substrates; Fourier transform infrared spectroscope (FTIR) was carried out on KBr tablets to investigate chemical composition and bonding structure; the morphology of the DLC coating was analyzed by atomic force microscope (AFM) on Si substrates. For the barrier properties of PET webs, we measured the oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) after coated with DLC films. We addressed the film barrier property related to process parameters, such as microwave power and pulse parameter in this work. The results show that the DLC coatings can greatly improve the barrier properties of PET webs.

  12. Influence of environmental parameters on the frictional behavior of DLC coatings

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y. [Louisiana State Univ., Baton Rouge, LA (United States). Mechanical Engineering Dept.; Erdemir, A.; Meletis, E.I. [Argonne National Lab., IL (United States). Energy Technology Div.

    1997-05-01

    In a previous studies it was shown that diamond like carbon (DLC) films possess low friction coefficient (f) and excellent wear resistance. The reduction in f was found to be consistent with a ``wear induced graphitization`` mechanism of the DLC structure. A recent study showed that operational parameters (sliding velocity and loading level) influence the tribological behavior of DLC film through control of the kinetics of the graphitization process. The objective of the present study was to investigate the influence of environmental parameters (humidity and temperature) on the tribological behavior of DLC film and provide further support to the wear induced graphitization mechanism. Ion beam deposition was utilized to deposit DLC on a SiC substrate. Pin-on-disc experiments were conducted by varying humidity (0%, 40% and 100%) and temperature ({minus}10 C and 25 C). As-deposited DLC and wear debris was characterized by transmission electron microscopy. It was found that lower humidity increases the graphitization rate more than likely due to the reduction in the effect by the water molecules. A decreased graphitization rate was observed at lower temperature and higher humidity and can be attributed to suppression of temperature rise at hot spots. The present findings are consistent with and further verify the wear induced graphitization mechanism.

  13. Study of Flux Ratio of C60 to Ar Cluster Ion for Hard DLC Film deposition

    International Nuclear Information System (INIS)

    Miyauchi, K.; Toyoda, N.; Kanda, K.; Matsui, S.; Kitagawa, T.; Yamada, I.

    2003-01-01

    To study the influence of the flux ratio of C60 molecule to Ar cluster ion on (diamond like carbon) DLC film characteristics, DLC films deposited under various flux ratios were characterized with Raman spectrometry and Near Edge X-ray Absorption Fine Structure (NEXAFS). From results of these measurements, hard DLC films were deposited when the flux ratio of C60 to Ar cluster ion was between 0.7 and 4. Furthermore the DLC film with constant sp2 content was obtained in the range of the ratio from 0.7 to 4, which contents are lower values than that of conventional films such as RF plasma. DLC films deposited under the ratio from 1 to 4 had hardness from 40 to 45GPa. It was shown that DLC films with stable properties of low sp2 content and high hardness were formed even when the fluxes were varied from 1 to 4 during deposition. It was indicated that this process was useful in the view of industrial application

  14. Effect of Surface Modification on Corrosion Resistance of Uncoated and DLC Coated Stainless Steel Surface

    Science.gov (United States)

    Scendo, Mieczyslaw; Staszewska-Samson, Katarzyna

    2017-08-01

    Corrosion resistance of 4H13 stainless steel (EN-X46Cr13) surface uncoated and coated with an amorphous hydrogenated carbon (a-C:H) film [diamond-like carbon (DLC)] in acidic chloride solution was investigated. The DLC films were deposited on steel surface by a plasma deposition, direct current discharge (PDCD) method. The Fourier transform infrared (FTIR) was used to determine the chemical groups existing on DLC films. The surface of the specimens was observed by a scanning electron microscope (SEM). The tribological properties of the both materials were examined using a ball-on disk tribometer. The microhardness (HV) of diamond-like carbon film increased over five times in relation to the 4H13 stainless steel without of DLC coating. Oxidation kinetic parameters were determined by gravimetric and electrochemical methods. The high value of polarization resistance indicates that the DLC film on substrate was characterized by low electrical conductivity. The corrosion rate of 4H13 stainless steel with of DLC film decreased about eight times in relation to uncoated surface of 4H13 stainless steel.

  15. FIB and TEM studies of damage mechanisms in DLC coatings sliding against aluminum

    International Nuclear Information System (INIS)

    Meng-Burany, X.; Alpas, A.T.

    2007-01-01

    Material transfer and adhesion phenomena during sliding contact of non-hydrogenated diamond like carbon (DLC) coatings against an aluminum-silicon (319 Al) counterface tested in vacuum were studied using TEM investigations of the cross-sectional microstructures of the wear tracks. Site-specific focused ion beam (FIB) lift-out method was used to prepare the sections at the precise locations where aluminum pieces were adhered to the DLC surface. The dense amorphous structure of DLC coatings with nanocrystalline graphite platelets is confirmed by the high-resolution transmission electron microscopy. The focused ion channeling contrast images obtained from the cross-sections of the wear track indicated that in some sections of DLC coatings considerable wear was inflicted by aluminum, reducing the coating thickness. The aluminum that was transferred on the DLC coatings' contact surfaces consisted of nanocrystalline grains of less than 100 nm. TEM examination of the contact surface of the 319 Al pin has revealed that the initial aluminum grain size was also reduced to the nanocrystalline scale and this was accompanied with a hardness increase. These observations revealed that local severe plastic deformation accompanied the aluminum adhesion process to DLC coating surfaces

  16. Biological responses of diamond-like carbon (DLC) films with different structures in biomedical application.

    Science.gov (United States)

    Liao, T T; Zhang, T F; Li, S S; Deng, Q Y; Wu, B J; Zhang, Y Z; Zhou, Y J; Guo, Y B; Leng, Y X; Huang, N

    2016-12-01

    Diamond-like carbon (DLC) films are potential candidates for artificial joint surface modification in biomedical applications, and the influence of the structural features of DLC surfaces on cell functions has attracted attention in recent decades. Here, the biocompatibility of DLC films with different structures was investigated using macrophages, osteoblasts and fibroblasts. The results showed that DLC films with a low ratio of sp(2)/sp(3), which tend to have a structure similar to that of diamond, led to less inflammatory, excellent osteogenic and fibroblastic reactions, with higher cell viability, better morphology, lower release of TNF-α (tumor necrosis factor-α) and IL-6 (interleukin-6), and higher release of IL-10 (interleukin-10). The results also demonstrated that the high-density diamond structure (low ratio of sp(2)/sp(3)) of DLC films is beneficial for cell adhesion and growth because of better protein adsorption without electrostatic repulsion. These findings provide valuable insights into the mechanisms underlying inhibition of an inflammatory response and the promotion of osteoblastogenesis and fibrous propagation, and effectively build a system for evaluating the biocompatibility of DLC films. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Mechanical properties of fluorinated DLC and Si interlayer on a Ti biomedical alloy

    International Nuclear Information System (INIS)

    Chou, Chau-Chang; Wu, Yi-Yang; Lee, Jyh-Wei; Huang, Jen-Ching; Yeh, Chi-Hsiao

    2013-01-01

    Fluorinated amorphous diamond-like carbon (F-DLC) films were deposited on Ti6Al4V substrates by radio frequency plasma enhanced chemical vapor deposition (rf PECVD) technique using a mixture of methane (CH 4 ) and tetrafluoromethane (CF 4 ) gasses. A 100 nm Si interlayer was coated in advance by physical vapor deposition (PVD) process to improve the adhesion between F-DLC and Ti alloy. The structure and surface properties of F-DLC coatings, prepared by various fluorine flow ratios, were investigated by using X-ray diffraction spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The mechanical properties were evaluated by nano-indentation, and the adhesion, by micro-scratch. The results showed that a moderate incorporation of the fluorine content in the DLC films can still maintain acceptable mechanical properties, which, on the other hand, obtains remarkable benefits of blood compatibility and anti-corrosion. - Highlights: ► F-DLC’s sp2 carbon cluster increases with the precursors’ CF 4 /CH 4 ratio. ► F-DLC’s reduced elastic modulus and hardness decrease with the CF 4 /CH 4 ratio. ► F-DLC film’s adhesion strength degrades as the CF 4 /CH 4 ratio elevated. ► An F-DLC deposited Ti6Al4V produced by a smaller CF 4 /CH 4 ratio, 1-3, is suggested

  18. Corrosion behavior of aluminum doped diamond-like carbon thin films in NaCl aqueous solution.

    Science.gov (United States)

    Khun, N W; Liu, E

    2010-07-01

    Aluminum doped diamond-like carbon (DLC:Al) thin films were deposited on n-Si(100) substrates by co-sputtering a graphite target under a fixed DC power (650 W) and an aluminum target under varying DC power (10-90 W) at room temperature. The structure, adhesion strength and surface morphology of the DLC:Al films were characterized by X-ray photoelectron spectroscopy (XPS), micro-scratch testing and atomic force microscopy (AFM), respectively. The corrosion performance of the DLC:Al films was investigated by means of potentiodynamic polarization testing in a 0.6 M NaCl aqueous solution. The results showed that the polarization resistance of the DLC:Al films increased from about 18 to 30.7 k(omega) though the corrosion potentials of the films shifted to more negative values with increased Al content in the films.

  19. Structural characteristics of surface-functionalized nitrogen-doped diamond-like carbon films and effective adjustment to cell attachment

    International Nuclear Information System (INIS)

    Liu Ai-Ping; Liu Min; Yu Jian-Can; Qian Guo-Dong; Tang Wei-Hua

    2015-01-01

    Nitrogen-doped diamond-like carbon (DLC:N) films prepared by the filtered cathodic vacuum arc technology are functionalized with various chemical molecules including dopamine (DA), 3-Aminobenzeneboronic acid (APBA), and adenosine triphosphate (ATP), and the impacts of surface functionalities on the surface morphologies, compositions, microstructures, and cell compatibility of the DLC:N films are systematically investigated. We demonstrate that the surface groups of DLC:N have a significant effect on the surface and structural properties of the film. The activity of PC12 cells depends on the particular type of surface functional groups of DLC:N films regardless of surface roughness and wettability. Our research offers a novel way for designing functionalized carbon films as tailorable substrates for biosensors and biomedical engineering applications. (paper)

  20. Structural characteristics of surface-functionalized nitrogen-doped diamond-like carbon films and effective adjustment to cell attachment

    Science.gov (United States)

    Liu, Ai-Ping; Liu, Min; Yu, Jian-Can; Qian, Guo-Dong; Tang, Wei-Hua

    2015-05-01

    Nitrogen-doped diamond-like carbon (DLC:N) films prepared by the filtered cathodic vacuum arc technology are functionalized with various chemical molecules including dopamine (DA), 3-Aminobenzeneboronic acid (APBA), and adenosine triphosphate (ATP), and the impacts of surface functionalities on the surface morphologies, compositions, microstructures, and cell compatibility of the DLC:N films are systematically investigated. We demonstrate that the surface groups of DLC:N have a significant effect on the surface and structural properties of the film. The activity of PC12 cells depends on the particular type of surface functional groups of DLC:N films regardless of surface roughness and wettability. Our research offers a novel way for designing functionalized carbon films as tailorable substrates for biosensors and biomedical engineering applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 51272237, 51272231, and 51010002) and the China Postdoctoral Science Foundation (Grant Nos. 2012M520063, 2013T60587, and Bsh1201016).

  1. Optimization of pulsed DC PACVD parameters: Toward reducing wear rate of the DLC films

    International Nuclear Information System (INIS)

    Ebrahimi, Mansoureh; Mahboubi, Farzad; Naimi-Jamal, M. Reza

    2016-01-01

    Highlights: • Effect of pulsed DC PACVD deposition temperature, duty cycle, hydrogen flow and argon/CH4 flow ratio on the wear rate and durability of DLC films was studied. • Results show that wear rate of the DLC films, reduced from 14×E-4 mm3/Nm to 1×E-6 mm3/Nm with increasing the duty cycle from 50% to 80%. • In low duty cycle (around 50%), wear rate increases with increasing in Argon/CH4 flow ratio. • Oxidation, fatigue, abrasion and graphitization are main wear mechanisms in the DLC film. - Abstract: The effect of pulsed direct current (DC) plasma-assisted chemical vapor deposition (PACVD) parameters such as temperature, duty cycle, hydrogen flow, and argon/CH_4 flow ratio on the wear behavior and wear durability of the diamond-like carbon (DLC) films was studied by using response surface methodology (RSM). DLC films were deposited on nitrocarburized AISI 4140 steel. Wear rate and wear durability of the DLC films were examined with the pin-on-disk method. Field emission scanning electron microscopy, Raman spectroscopy, and nanoindentation techniques were used for studying wear mechanisms, chemical structure, and hardness of the DLC films. RSM results show that duty cycle is one of the important parameters that affect the wear rate of the DLC samples. The wear rate of the samples deposited with a duty cycle of >75% decreases with an increase in the argon/CH4 ratio. In contrast, for a duty cycle of <65%, the wear rate increases with an increase in the argon/CH_4 ratio. The wear durability of the DLC samples increases with an increase in the duty cycle, hydrogen flow, and argon/CH_4 flow ratio at the deposition temperature between 85 °C and 110 °C. Oxidation, fatigue, abrasive wear, and graphitization are the wear mechanisms observed on the wear scar of the DLC samples deposited with the optimum deposition conditions.

  2. Optimization of pulsed DC PACVD parameters: Toward reducing wear rate of the DLC films

    Energy Technology Data Exchange (ETDEWEB)

    Ebrahimi, Mansoureh [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, P.O. Box 1875-4413, Tehran (Iran, Islamic Republic of); Mahboubi, Farzad, E-mail: mahboubi@aut.ac.ir [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, P.O. Box 1875-4413, Tehran (Iran, Islamic Republic of); Naimi-Jamal, M. Reza [Research Laboratory of Green Organic Synthesis and Polymers, Department of Chemistry, Iran University of Science and Technology, P.O. Box 16846, Tehran (Iran, Islamic Republic of)

    2016-12-15

    Highlights: • Effect of pulsed DC PACVD deposition temperature, duty cycle, hydrogen flow and argon/CH4 flow ratio on the wear rate and durability of DLC films was studied. • Results show that wear rate of the DLC films, reduced from 14×E-4 mm3/Nm to 1×E-6 mm3/Nm with increasing the duty cycle from 50% to 80%. • In low duty cycle (around 50%), wear rate increases with increasing in Argon/CH4 flow ratio. • Oxidation, fatigue, abrasion and graphitization are main wear mechanisms in the DLC film. - Abstract: The effect of pulsed direct current (DC) plasma-assisted chemical vapor deposition (PACVD) parameters such as temperature, duty cycle, hydrogen flow, and argon/CH{sub 4} flow ratio on the wear behavior and wear durability of the diamond-like carbon (DLC) films was studied by using response surface methodology (RSM). DLC films were deposited on nitrocarburized AISI 4140 steel. Wear rate and wear durability of the DLC films were examined with the pin-on-disk method. Field emission scanning electron microscopy, Raman spectroscopy, and nanoindentation techniques were used for studying wear mechanisms, chemical structure, and hardness of the DLC films. RSM results show that duty cycle is one of the important parameters that affect the wear rate of the DLC samples. The wear rate of the samples deposited with a duty cycle of >75% decreases with an increase in the argon/CH4 ratio. In contrast, for a duty cycle of <65%, the wear rate increases with an increase in the argon/CH{sub 4} ratio. The wear durability of the DLC samples increases with an increase in the duty cycle, hydrogen flow, and argon/CH{sub 4} flow ratio at the deposition temperature between 85 °C and 110 °C. Oxidation, fatigue, abrasive wear, and graphitization are the wear mechanisms observed on the wear scar of the DLC samples deposited with the optimum deposition conditions.

  3. DLC nano-dot surfaces for tribological applications in MEMS devices

    International Nuclear Information System (INIS)

    Singh, R. Arvind; Na, Kyounghwan; Yi, Jin Woo; Lee, Kwang-Ryeol; Yoon, Eui-Sung

    2011-01-01

    With the invention of miniaturized devices like micro-electro-mechanical systems (MEMS), tribological studies at micro/nano-scale have gained importance. These studies are directed towards understanding the interactions between surfaces at micro/nano-scales, under relative motion. In MEMS devices, the critical forces, namely adhesion and friction restrict the smooth operation of the elements that are in relative motion. These miniaturized devices are traditionally made from silicon (Si), whose tribological properties are not good. In this paper, we present a short investigation of nano- and micro-tribological properties of diamond-like carbon (DLC) nano-dot surfaces. The investigation was undertaken to evaluate the potential of these surfaces for their possible application to the miniaturized devices. The tribological evaluation of the DLC nano-dot surfaces was done in comparison with bare Si (1 0 0) surfaces and DLC coated silicon surfaces. A commercial atomic force microscope (AFM) was used to measure adhesion and friction properties of the test materials at the nano-scale, whereas a custom-built micro-tribotester was used to measure their micro-friction property. Results showed that the DLC nano-dot surfaces exhibited superior tribological properties with the lowest values of adhesion force, and friction force both at the nano- and micro-scales, when compared to the bare Si (1 0 0) surfaces and DLC coated silicon surfaces. In addition, the DLC nano-dot surfaces showed no observable wear at the micro-scale, unlike the other two test materials. The superior tribological performance of the DLC nano-dot surfaces is attributed to their hydrophobic nature and the reduced area of contact projected by them.

  4. DLC nano-dot surfaces for tribological applications in MEMS devices

    Energy Technology Data Exchange (ETDEWEB)

    Singh, R. Arvind; Na, Kyounghwan [Nano-Bio Research Center, Korea Institute of Science and Technology, 39-1, Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Yi, Jin Woo; Lee, Kwang-Ryeol [Computational Science Center, Korea Institute of Science and Technology, 39-1, Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Yoon, Eui-Sung, E-mail: esyoon@kist.re.kr [Nano-Bio Research Center, Korea Institute of Science and Technology, 39-1, Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of)

    2011-02-01

    With the invention of miniaturized devices like micro-electro-mechanical systems (MEMS), tribological studies at micro/nano-scale have gained importance. These studies are directed towards understanding the interactions between surfaces at micro/nano-scales, under relative motion. In MEMS devices, the critical forces, namely adhesion and friction restrict the smooth operation of the elements that are in relative motion. These miniaturized devices are traditionally made from silicon (Si), whose tribological properties are not good. In this paper, we present a short investigation of nano- and micro-tribological properties of diamond-like carbon (DLC) nano-dot surfaces. The investigation was undertaken to evaluate the potential of these surfaces for their possible application to the miniaturized devices. The tribological evaluation of the DLC nano-dot surfaces was done in comparison with bare Si (1 0 0) surfaces and DLC coated silicon surfaces. A commercial atomic force microscope (AFM) was used to measure adhesion and friction properties of the test materials at the nano-scale, whereas a custom-built micro-tribotester was used to measure their micro-friction property. Results showed that the DLC nano-dot surfaces exhibited superior tribological properties with the lowest values of adhesion force, and friction force both at the nano- and micro-scales, when compared to the bare Si (1 0 0) surfaces and DLC coated silicon surfaces. In addition, the DLC nano-dot surfaces showed no observable wear at the micro-scale, unlike the other two test materials. The superior tribological performance of the DLC nano-dot surfaces is attributed to their hydrophobic nature and the reduced area of contact projected by them.

  5. Macrophages adhesion rate on Ti-6Al-4V substrates: polishing and DLC coating effects

    Directory of Open Access Journals (Sweden)

    Everton Diniz dos Santos

    Full Text Available Abstract Introduction Various works have shown that diamond-like carbon (DLC coatings are able to improve the cells adhesion on prosthesis material and also cause protection against the physical wear. On the other hand there are reports about the effect of substrate polishing, in evidence of that roughness can enhance cell adhesion. In order to compare and quantify the joint effects of both factors, i.e, polishing and DLC coating, a commonly prosthesis material, the Ti-6Al-4V alloy, was used as raw material for substrates in our studies of macrophage cell adhesion rate on rough and polished samples, coated and uncoated with DLC. Methods The films were produced by PECVD technique on Ti-6Al-4V substrates and characterized by optical profilometry, scanning electron microscopy and Raman spectroscopy. The amount of cells was measured by particle analysis in IMAGE J software. Cytotoxicity tests were also carried out to infer the biocompatibility of the samples. Results The results showed that higher the surface roughness of the alloy, higher are the cells fixing on the samples surface, moreover group of samples with DLC favored the cell adhesion more than their respective uncoated groups. The cytotoxity tests confirmed that all samples were biocompatible independently of being polished or coated with DLC. Conclusion From the observed results, it was found that the rougher substrate coated with DLC showed a higher cell adhesion than the polished samples, either coated or uncoated with the film. It is concluded that the roughness of the Ti-6Al-4V alloy and the DLC coating act complementary to enhance cell adhesion.

  6. Dlc1 interaction with non-muscle myosin heavy chain II-A (Myh9 and Rac1 activation

    Directory of Open Access Journals (Sweden)

    Mohammad G. Sabbir

    2016-04-01

    Full Text Available The Deleted in liver cancer 1 (Dlc1 gene codes for a Rho GTPase-activating protein that also acts as a tumour suppressor gene. Several studies have consistently found that overexpression leads to excessive cell elongation, cytoskeleton changes and subsequent cell death. However, none of these studies have been able to satisfactorily explain the Dlc1-induced cell morphological phenotypes and the function of the different Dlc1 isoforms. Therefore, we have studied the interacting proteins associated with the three major Dlc1 transcriptional isoforms using a mass spectrometric approach in Dlc1 overexpressing cells. We have found and validated novel interacting partners in constitutive Dlc1-expressing cells. Our study has shown that Dlc1 interacts with non-muscle myosin heavy chain II-A (Myh9, plectin and spectrin proteins in different multiprotein complexes. Overexpression of Dlc1 led to increased phosphorylation of Myh9 protein and activation of Rac1 GTPase. These data support a role for Dlc1 in induced cell elongation morphology and provide some molecular targets for further analysis of this phenotype.

  7. In vitro and in vivo investigations into the biocompatibility of diamond-like carbon (DLC) coatings for orthopedic applications.

    Science.gov (United States)

    Allen, M; Myer, B; Rushton, N

    2001-05-01

    Diamond-like carbon (DLC) shows great promise as a durable, wear- and corrosion-resistant coating for biomedical implants. The effects of DLC coatings on the musculoskeletal system have not been investigated in detail. In this study, DLC coatings were deposited on polystyrene 24-well tissue culture plates by fast-atom bombardment from a hexane precursor. Two osteoblast-like cell lines were cultured on uncoated and DLC-coated plates for periods of up to 72 h. The effects of DLC coatings on cellular metabolism were investigated by measuring the production of three osteoblast-specific marker proteins: alkaline phosphatase, osteocalcin, and type I collagen. There was no evidence that the presence of the DLC coating had any adverse effect on any of the parameters measured in this study. In a second series of experiments, DLC-coated cobalt-chromium cylinders were implanted in intramuscular locations in rats and in transcortical sites in sheep. Histologic analysis of specimens retrieved 90 days after surgery showed that the DLC-coated specimens were well tolerated in both sites. These data indicate that DLC coatings are biocompatible in vitro and in vivo, and further investigations into their long-term biological and tribological performance are now warranted. Copyright 2001 John Wiley & Sons, Inc.

  8. Influence of duty ratio of pulsed bias on structure and properties of silicon-doped diamond-like carbon films by plasma deposition

    International Nuclear Information System (INIS)

    Nakazawa, Hideki; Kamata, Ryosuke; Miura, Soushi; Okuno, Saori

    2013-01-01

    We have investigated the influence of the duty ratio of pulsed substrate bias on the structure and properties of Si-doped diamond-like carbon (Si-DLC) films deposited by radio frequency plasma-enhanced chemical vapor deposition using CH 4 , Ar, and monomethylsilane (CH 3 SiH 3 ) as the Si source. The Si/(Si + C) ratios in the Si-DLC films deposited using pulsed bias were higher than that of the dc-biased Si-DLC film, and the Si fraction increased with decreasing pulse duty ratio. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses revealed that Si-C, Si-H n , and C-H n bonds in the Si-DLC films increased with decreasing duty ratio. The internal stress decreased as the duty ratio decreased, which is probably due to the increase in Si-C, Si-H n , and C-H n bonds in the films. The Si-DLC films deposited using pulsed bias had higher adhesion strength than the dc-biased Si-DLC film because of the further reduction of internal stress. At higher duty ratios, although the Si fractions of the pulse-biased Si-DLC films were higher than that of the dc-biased Si-DLC film, the wear rates of the former were less than that of the latter. - Highlights: • The internal stress of Si-doped films was lowered at lower duty ratios. • The adhesion of pulse-biased films was improved compared with that of dc films. • The tribological properties of Si-doped films were improved by the use of pulse bias

  9. Covalent and non-covalent functionalization and solubilization of ...

    Indian Academy of Sciences (India)

    Wintec

    photographs of the dispersions of amide-functio- nalized DWNTs in dichloromethane and tetrahydro- furan. In figure 3b, we show a TEM image of DWNTs after covalent functionalization. The images are not as sharp after functionalization as in the case of pris- tine nanotubes (figure 3a), and the bundles seem to be intact.

  10. The effect of fluoroalkylsilanes on tribological properties and wettability of Si-DLC coatings

    Science.gov (United States)

    Bystrzycka, E.; Prowizor, M.; Piwoński, I.; Kisielewska, A.; Batory, D.; Jędrzejczak, A.; Dudek, M.; Kozłowski, W.; Cichomski, M.

    2018-03-01

    Silicon-containing diamond-like carbon (Si-DLC) coatings were prepared on silicon wafers by Radio Frequency Plasma Enhanced Chemical Vapor Deposition (RF-PECVD) method using methane/hexamethyl-disiloxane atmosphere. Herein, we report that Si-DLC coatings can be effectively modified by fluoroalkylsilanes which results in significant enhancement of frictional and wettability properties. Two types of fluoroalkylsilanes differing in the length of fluorocarbon chains were deposited on Si-DLC coatings with the use of Vapor Phase Deposition (VPD) method. The chemical composition of Si-DLC coatings and effectiveness of modification with fluoroalkylsilanes were confirmed by Fourier Transform Infrared Spectroscopy (FTIR) and x-ray Photoelectron Spectroscopy (XPS). Frictional properties in microscale were investigated with the use of ball-on-flat apparatus operating at millinewton (mN) load range. It was found that the presence of silicon enhances the chemisorption of fluoroalkylsilanes on Si-DLC coatings by creating adsorption anchoring centers. In consequence, a decrease of adhesion and an increase of hydrophobicity along with a decrease of coefficient of friction were observed. Experimental results indicate, that tribological properties are correlated with dispersive and acid-base components of the surface free energy as well as with the work of adhesion.

  11. DLC coating on stainless steel by pulsed methane discharge in repetitive plasma focus

    International Nuclear Information System (INIS)

    Hassan, M.; Qayyum, A.; Ahmad, S.; Mahmood, S.; Shafiq, M.; Zakaullah, M.; Lee, P.; Rawat, R.S.

    2014-01-01

    Amorphous hydrogenated carbon (a-C:H)/diamond-like carbon (DLC) coatings have been achieved on AISI 304 stainless steel (SS) substrates by employing energetic ions emitted from a repetitive plasma focus operated in CH 4 discharge. The Raman spectroscopy of the coatings exhibits the evolution of a-C:H/DLC coatings with clearly observed D and G peaks centered about 1320–1360 and 1560–1620 cm −1 respectively. The diamond character of the coatings is influenced by the ion flux and repetition rate of the focus device. The repetitive discharge mode of plasma focus has led to the formation of a-C:H/DLC coatings in short duration of time. The coatings transform from a-C to a-C:H depending upon substrate angular position. X-ray diffraction (XRD) analysis confirms the formation of DLC coating owing to stress-induced restructuring in SS. The estimated crystallite size is found to be ∼40–50 nm. Field emission scanning electron micrographs exhibit a layered granular surface morphology of the coatings. The Vickers surface hardness of the DLC coated SS samples has been significantly improved.

  12. DLC coating on stainless steel by pulsed methane discharge in repetitive plasma focus

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, M., E-mail: hassanjh@gmail.com [Department of Physics, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, BLK7, 1 Nanyang Walk, Singapore 637616 (Singapore); Qayyum, A.; Ahmad, S. [National Tokamak Fusion Program, 3329 Islamabad (Pakistan); Mahmood, S. [Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, BLK7, 1 Nanyang Walk, Singapore 637616 (Singapore); Department of Physics, University of Karachi, 75270 Karachi (Pakistan); Shafiq, M.; Zakaullah, M. [Department of Physics, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Lee, P.; Rawat, R.S. [Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, BLK7, 1 Nanyang Walk, Singapore 637616 (Singapore)

    2014-06-01

    Amorphous hydrogenated carbon (a-C:H)/diamond-like carbon (DLC) coatings have been achieved on AISI 304 stainless steel (SS) substrates by employing energetic ions emitted from a repetitive plasma focus operated in CH{sub 4} discharge. The Raman spectroscopy of the coatings exhibits the evolution of a-C:H/DLC coatings with clearly observed D and G peaks centered about 1320–1360 and 1560–1620 cm{sup −1} respectively. The diamond character of the coatings is influenced by the ion flux and repetition rate of the focus device. The repetitive discharge mode of plasma focus has led to the formation of a-C:H/DLC coatings in short duration of time. The coatings transform from a-C to a-C:H depending upon substrate angular position. X-ray diffraction (XRD) analysis confirms the formation of DLC coating owing to stress-induced restructuring in SS. The estimated crystallite size is found to be ∼40–50 nm. Field emission scanning electron micrographs exhibit a layered granular surface morphology of the coatings. The Vickers surface hardness of the DLC coated SS samples has been significantly improved.

  13. Deposition of DLC Film on Stainless Steel Substrates Coated by Nickel Using PECVD Method.

    Science.gov (United States)

    Khalaj, Zahra; Ghoranneviss, Mahmood; Vaghri, Elnaz; Saghaleini, Amir; Diudea, Mircea V

    2012-06-01

    Research on diamond-like carbon (DLC) films has been devoted to find both optimized conditions and characteristics of the deposited films on various substrates. In the present work, we investigate the quality of the DLC films grown on stainless steel substrates using different thickness of the nickel nanoparticle layers on the surface. Nickel nanoparticles were sputtered on the stainless steel substrates at 200 °C by a DC-sputtering system to make a good adherence between DLC coating and steel substrates. Atomic Force Microscopy was used to characterize the surface roughness and distribution function of the nickel nanoparticles on the substrate surface. Diamond like carbon films were deposited on stainless steel substrates coated by nickel using pure acetylene and C2H2/H2 with 15% flow ratio by DC-Plasma Enhanced Chemical Vapor Deposition (PECVD) systems. Microstructural analysis by Raman spectroscopy showed a low intensity ratio ID/IG for DLC films by increasing the Ni layer thickness on the stainless steel substrates. Fourier Transforms Infrared spectroscopy (FTIR) evidenced the peaks attributed to C-H bending and stretching vibration modes in the range of 1300-1700 cm-1 and 2700-3100 cm-1, respectively, in good agreement with the Raman spectroscopy and confirmed the DLC growth in all samples.

  14. Chemistry of Covalent Organic Frameworks.

    Science.gov (United States)

    Waller, Peter J; Gándara, Felipe; Yaghi, Omar M

    2015-12-15

    Linking organic molecules by covalent bonds into extended solids typically generates amorphous, disordered materials. The ability to develop strategies for obtaining crystals of such solids is of interest because it opens the way for precise control of the geometry and functionality of the extended structure, and the stereochemical orientation of its constituents. Covalent organic frameworks (COFs) are a new class of porous covalent organic structures whose backbone is composed entirely of light elements (B, C, N, O, Si) that represent a successful demonstration of how crystalline materials of covalent solids can be achieved. COFs are made by combination of organic building units covalently linked into extended structures to make crystalline materials. The attainment of crystals is done by several techniques in which a balance is struck between the thermodynamic reversibility of the linking reactions and their kinetics. This success has led to the expansion of COF materials to include organic units linked by these strong covalent bonds: B-O, C-N, B-N, and B-O-Si. Since the organic constituents of COFs, when linked, do not undergo significant change in their overall geometry, it has been possible to predict the structures of the resulting COFs, and this advantage has facilitated their characterization using powder X-ray diffraction (PXRD) techniques. It has also allowed for the synthesis of COF structures by design and for their formation with the desired composition, pore size, and aperture. In practice, the modeled PXRD pattern for a given expected COF is compared with the experimental one, and depending on the quality of the match, this is used as a starting point for solving and then refining the crystal structure of the target COF. These characteristics make COFs an attractive class of new porous materials. Accordingly, they have been used as gas storage materials for energy applications, solid supports for catalysis, and optoelectronic devices. A large and

  15. The thickness of DLC thin film affects the thermal conduction of HPLED lights

    Science.gov (United States)

    Hsu, Ming Seng; Huang, Jen Wei; Shyu, Feng Lin

    2016-09-01

    Thermal dissipation had an important influence in the quantum effect and life of light emitting diodes (LED) because it enabled heat transfer away from electric devices to the aluminum plate for heat removal. In the industrial processing, the quality of the thermal dissipation was decided by the gumming technique between the PCB and aluminum plate. In this study, we made the ceramic thin films of diamond like carbon (DLC) by vacuum sputtering between the substrate and high power light emitting diodes (HPLED) light to check the influence of heat transfer by DLC thin films. The ceramic dielectric coatings were characterized by several subsequent analyses, especially the measurement of real work temperature of HPLEDs. The X-Ray photoelectron spectroscopy (XPS) patterns revealed that ceramic phases were successfully grown onto the substrate. At the same time, the real work temperatures showed the thickness of DLC thin film coating effectively affected the thermal conduction of HPLEDs.

  16. Plasma immersion ion implantation and deposition of DLC coating for modification of orthodontic magnets

    International Nuclear Information System (INIS)

    Wongsarat, W.; Sarapirom, S.; Aukkaravittayapun, S.; Jotikasthira, D.; Boonyawan, D.; Yu, L.D.

    2012-01-01

    This study was aimed to use the plasma immersion ion implantation and deposition (PIII-D) technique to form diamond-like carbon (DLC) thin films on orthodontic magnets to solve the corrosion problem. To search for the optimal material modification effect, PIII-D conditions including gases, processing time, and pulsing mode were varied. The formation of DLC films was confirmed and characterized with Raman spectra. The intensity of the remnant magnetic field of the magnets and the hardness, adhesion and thickness of the thin films were then measured. A corrosion test was carried out using clinic dental fluid. Improved benefits including a satisfying hardness, adhesion, remnant magnetic strength and corrosion resistance of the DLC coating could be achieved by using a higher interrupting time ratio and shorter processing time.

  17. Plasma immersion ion implantation and deposition of DLC coating for modification of orthodontic magnets

    Energy Technology Data Exchange (ETDEWEB)

    Wongsarat, W. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Sarapirom, S. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); National Metal and Materials Technology Center, 114 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani, Bangkok 12120 (Thailand); Aukkaravittayapun, S. [National Metal and Materials Technology Center, 114 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani, Bangkok 12120 (Thailand); Jotikasthira, D. [Department of Odontology-Oral Pathology, Faculty of Dentistry, Chiang Mai University, Chiang Mai 50200 (Thailand); Boonyawan, D. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@fnrf.science.cmu.ac.th [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

    2012-02-01

    This study was aimed to use the plasma immersion ion implantation and deposition (PIII-D) technique to form diamond-like carbon (DLC) thin films on orthodontic magnets to solve the corrosion problem. To search for the optimal material modification effect, PIII-D conditions including gases, processing time, and pulsing mode were varied. The formation of DLC films was confirmed and characterized with Raman spectra. The intensity of the remnant magnetic field of the magnets and the hardness, adhesion and thickness of the thin films were then measured. A corrosion test was carried out using clinic dental fluid. Improved benefits including a satisfying hardness, adhesion, remnant magnetic strength and corrosion resistance of the DLC coating could be achieved by using a higher interrupting time ratio and shorter processing time.

  18. Impact of laser power density on tribological properties of Pulsed Laser Deposited DLC films

    Science.gov (United States)

    Gayathri, S.; Kumar, N.; Krishnan, R.; AmirthaPandian, S.; Ravindran, T. R.; Dash, S.; Tyagi, A. K.; Sridharan, M.

    2013-12-01

    Fabrication of wear resistant and low friction carbon films on the engineered substrates is considered as a challenging task for expanding the applications of diamond-like carbon (DLC) films. In this paper, pulsed laser deposition (PLD) technique is used to deposit DLC films on two different types of technologically important class of substrates such as silicon and AISI 304 stainless steel. Laser power density is one of the important parameter used to tailor the fraction of sp2 bonded amorphous carbon (a-C) and tetrahedral amorphous carbon (ta-C) made by sp3 domain in the DLC film. The I(D)/I(G) ratio decreases with the increasing laser power density which is associated with decrease in fraction of a-C/ta-C ratio. The fraction of these chemical components is quantitatively analyzed by EELS which is well supported to the data obtained from the Raman spectroscopy. Tribological properties of the DLC are associated with chemical structure of the film. However, the super low value of friction coefficient 0.003 is obtained when the film is predominantly constituted by a-C and sp2 fraction which is embedded within the clusters of ta-C. Such a particular film with super low friction coefficient is measured while it was deposited on steel at low laser power density of 2 GW/cm2. The super low friction mechanism is explained by low sliding resistance of a-C/sp2 and ta-C clusters. Combination of excellent physical and mechanical properties of wear resistance and super low friction coefficient of DLC films is desirable for engineering applications. Moreover, the high friction coefficient of DLC films deposited at 9GW/cm2 is related to widening of the intergrain distance caused by transformation from sp2 to sp3 hybridized structure.

  19. Electrical properties of multilayer (DLC-TiC) films produced by pulsed laser deposition

    Science.gov (United States)

    Alawajji, Raad A.; Kannarpady, Ganesh K.; Nima, Zeid A.; Kelly, Nigel; Watanabe, Fumiya; Biris, Alexandru S.

    2018-04-01

    In this work, pulsed laser deposition was used to produce a multilayer diamond like carbon (ML (DLC-TiC)) thin film. The ML (DLC-TiC) films were deposited on Si (100) and glass substrates at various substrate temperatures in the range of 20-450 °C. Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), and atomic force microscopy were utilized to characterize the prepared films. Raman analysis revealed that as the substrate temperature increased, the G-peak position shifted to a higher raman shift and the full width at half maximum of the G and D bands decreased. XPS analysis indicated a decrease in sp3/sp2 ratio and an increase in Ti-C bond intensity when the substrate temperature was increased. Additionally, the surface roughness of ML (DLC-TiC) filmswas affected by the type and temperature of the substrate. The electrical measurement results indicated that the electrical resistivity of the ML (DLC-TiC) film deposited on Si and glass substrates showed the same behavior-the resistivity decreased when substrate temperature increased. Furthermore, the ML (DLC-TiC) films deposited on silicon showed lower electrical resistivity, dropping from 8.39E-4 Ω-cm to 5.00E-4 Ω-cm, and, similarly, the films on the glass substrate displayed a drop in electrical resistivity from 1.8E-2 Ω-cm to 1.2E-3 Ω-cm. These enhanced electrical properties indicate that the ML (DLC-TiC) films have widespread potential as transducers for biosensors in biological research; electrochemical electrodes, because these films can be chemically modified; biocompatible coatings for medicals tools; and more.

  20. Fabrication of Graphene Oxide Dispersed DLC/PDMS Substrates and Human Mesenchymal Stem Cell Culture(Researches)

    OpenAIRE

    伴, 雅人; Masahito, Ban

    2016-01-01

    Graphene Oxide (GO) dispersed DLC (diamond-like carbon) thin film deposited PDMS substrates were fabricated with plasma treatments and dip coating methods. It was found from cell culture tests using the substrates as scaffolds human mesenchymal stem cells (hMSCs) indicated larger F-actin areas compared with the substrates without GO and/or DLC.

  1. Solar cells based upon multicrystalline Si with DLC antireflection and passivating coatings

    International Nuclear Information System (INIS)

    Klyui, N.; Litovchenko, V.; Neselevska, L.; Kostylyov, V.; Sarikov, A.; Taraschenko, N.; Kittler, M.; Seifert, W.

    2006-01-01

    The characteristics of multicrystalline Si solar cells covered by diamond-like carbon (DLC) antireflection coatings been experimentally studied. It has been shown that this kind of coating provides a significant increase of the efficiency of solar cells mainly due to the increase of the short-circuit current density. The effects of antireflection and of the surface and bulk passivation on the SC current-voltage characteristics due to the DLC deposition have been investigated theoretically. Physical mechanisms underlying the observed effects have been proposed

  2. The characterisation of the microstructure and mechanical properties of diamond - like carbon (DLC for endoprosthesis

    Directory of Open Access Journals (Sweden)

    R. Gałuszka

    2017-01-01

    Full Text Available The paper presents the results of research of DLC coating of a - C:H type obtained by using a technique of physical vapor deposition (PVD on the surface of CoCrMo alloy, commonly used for the elements of the endoprosthesis. The surface has been observed using a scanning electron microscope (SEM. Analysis of the chemical composition and distribution of the different elements were performed using glow discharge optical emission spectrometry analysis (GDOES. It has been shown that the DLC elements are characterized by high hardness and good adhesion to the substrate.

  3. Properties of DLC coatings deposited by dc and dc with superimposed pulsed vacuum arc

    International Nuclear Information System (INIS)

    Zavaleyev, V.; Walkowicz, J.; Aksyonov, D.S.; Luchaninov, A.A.; Reshetnyak, E.N.; Strel'nitskij, V.E.

    2014-01-01

    Comparative studies of the structure, mechanical and tribological properties of DLC coatings deposited in DC and DC with superimposed high current pulse modes of operation vacuum-arc plasma source with the graphite cathode are presented. Imposition the pulses of high current on DC vacuum-arc discharge allows both increase the deposition rate of DLC coating and reduce the residual compressive stress in the coatings what promotes substantial improvement the adhesion to the substrate. Effect of vacuum arc plasma filtration with Venetian blind filter on the deposition rate and tribological characteristics of the coatings analyzed.

  4. Atomic Covalent Functionalization of Graphene

    Science.gov (United States)

    Johns, James E.; Hersam, Mark C.

    2012-01-01

    Conspectus Although graphene’s physical structure is a single atom thick, two-dimensional, hexagonal crystal of sp2 bonded carbon, this simple description belies the myriad interesting and complex physical properties attributed to this fascinating material. Because of its unusual electronic structure and superlative properties, graphene serves as a leading candidate for many next generation technologies including high frequency electronics, broadband photodetectors, biological and gas sensors, and transparent conductive coatings. Despite this promise, researchers could apply graphene more routinely in real-world technologies if they could chemically adjust graphene’s electronic properties. For example, the covalent modification of graphene to create a band gap comparable to silicon (~1 eV) would enable its use in digital electronics, and larger band gaps would provide new opportunities for graphene-based photonics. Towards this end, researchers have focused considerable effort on the chemical functionalization of graphene. Due to its high thermodynamic stability and chemical inertness, new methods and techniques are required to create covalent bonds without promoting undesirable side reactions or irreversible damage to the underlying carbon lattice. In this Account, we review and discuss recent theoretical and experimental work studying covalent modifications to graphene using gas phase atomic radicals. Atomic radicals have sufficient energy to overcome the kinetic and thermodynamic barriers associated with covalent reactions on the basal plane of graphene but lack the energy required to break the C-C sigma bonds that would destroy the carbon lattice. Furthermore, because they are atomic species, radicals substantially reduce the likelihood of unwanted side reactions that confound other covalent chemistries. Overall, these methods based on atomic radicals show promise for the homogeneous functionalization of graphene and the production of new classes of two

  5. Hybrid laser technology for creation of doped biomedical layers

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Miroslav; Bačáková, Lucie; Remsa, Jan; Kocourek, Tomáš; Mikšovský, Jan; Písařík, Petr; Vandrovcová, Marta; Filová, Elena; Kubinová, Šárka

    2016-01-01

    Roč. 4, Jan (2016), s. 98-104 ISSN 2327-6045 R&D Projects: GA ČR(CZ) GA15-05864S; GA ČR(CZ) GA15-01558S Institutional support: RVO:68378271 ; RVO:67985823 ; RVO:68378041 Keywords : hybrid laser technology * biomaterials * thin Films * doped Layers * DLC Subject RIV: BM - Solid Matter Physics ; Magnetism; JJ - Other Materials (FGU-C)

  6. A DLC-Punch Array to Fabricate the Micro-Textured Aluminum Sheet for Boiling Heat Transfer Control

    Directory of Open Access Journals (Sweden)

    Tatsuhio Aizawa

    2018-03-01

    Full Text Available A diamond-like carbon (DLC film, coated on an SKD11 (alloy tool steel substrate, was shaped by plasma oxidation to form an assembly of DLC macro-pillars and to be used as a DLC-punch array that is micro-embossed into aluminum sheets. First, the SKD11 steel die substrate was prepared and DLC-coated to have a film thickness of 10 μm. This DLC coating worked as a punch material. The two-dimensional micro-patterns were printed onto this DLC film by maskless lithography. The unprinted DLC films were selectively removed by plasma oxidation to leave the three-dimensional DLC-punch array on the SKD11 substrate. Each DLC punch had a head of 3.5 μm × 3.5 μm and a height of 8 μm. This DLC-punch array was fixed into the cassette die set for a micro-embossing process using a table-top servo-stamper. Furthermore, through numerically controlled micro-embossing, an alignment of rectangular punches was transcribed into a micro-cavity array in the aluminum sheet. The single micro-cavity had a bottom surface of 3.2 μm × 3.2 μm and an average depth of 7.5 μm. A heat-transfer experiment in boiling water was also performed to investigate the effect of micro-cavity texture on bubbling behavior and the boiling curve.

  7. Corrosion and Wear Behaviors of Cr-Doped Diamond-Like Carbon Coatings

    Science.gov (United States)

    Viswanathan, S.; Mohan, L.; Bera, Parthasarathi; Kumar, V. Praveen; Barshilia, Harish C.; Anandan, C.

    2017-08-01

    A combination of plasma-enhanced chemical vapor deposition and magnetron sputtering techniques has been employed to deposit chromium-doped diamond-like carbon (DLC) coatings on stainless steel, silicon and glass substrates. The concentrations of Cr in the coatings are varied by changing the parameters of the bipolar pulsed power supply and the argon/acetylene gas composition. The coatings have been studied for composition, morphology, surface nature, nanohardness, corrosion resistance and wear resistance properties. The changes in I D / I G ratio with Cr concentrations have been obtained from Raman spectroscopy studies. Ratio decreases with an increase in Cr concentration, and it has been found to increase at higher Cr concentration, indicating the disorder in the coating. Carbide is formed in Cr-doped DLC coatings as observed from XPS studies. There is a decrease in sp 3/ sp 2 ratios with an increase in Cr concentration, and it increases again at higher Cr concentration. Nanohardness studies show no clear dependence of hardness on Cr concentration. DLC coatings with lower Cr contents have demonstrated better corrosion resistance with better passive behavior in 3.5% NaCl solution, and corrosion potential is observed to move toward nobler (more positive) values. A low coefficient of friction (0.15) at different loads is observed from reciprocating wear studies. Lower wear volume is found at all loads on the Cr-doped DLC coatings. Wear mechanism changes from abrasive wear on the substrate to adhesive wear on the coating.

  8. Influence of ion bombardment on growth and properties of PLD created DLC films

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Miroslav; Písařík, Petr; Kocourek, Tomáš; Zemek, Josef; Lukeš, J.

    2013-01-01

    Roč. 110, č. 4 (2013), s. 943-947 ISSN 0947-8396 R&D Projects: GA MŠk LD12069 Institutional research plan: CEZ:AV0Z10100522 Keywords : DLC * ion bombardment * sp3 /sp2 * thin films * PLD Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.694, year: 2013

  9. Tribological behavior of DLC films deposited on nitrided and post-oxidized stainless steel by PACVD

    Science.gov (United States)

    Dalibon, E. L.; Brühl, S. P.; Heim, D.

    2012-06-01

    In this work, the tribological behavior and adhesion of DLC films deposited by PACVD on AISI 420 martensitic stainless steel was evaluated. Prior to DLC deposition, the samples were nitrided and some of them also post-oxidized. The films were characterized by Raman and EDS, microhardness was assessed with Vickers indenter and the microstructure was analyzed by OM, SEM, FIB. Fretting and linear reciprocating sliding tests were performed using a WC ball as counterpart, and the adhesion of the DLC films was characterized using the Scratch Test and Rockwell C indentation. Corrosion behavior was evaluated by the Salt Spray Fog Test. The film showed a hardness of only about 1500 HV but it was about 15-20 microns thick. The results of the mechanical tests showed that pre-treatments (nitriding and oxidizing) of the substrate did not have a big influence in the tribological behavior of the coating. However, the nitriding treatment before the DLC coating process reduced the interface stress and enhanced the adhesion. Additionally, all the films evidenced good corrosion resistance in a saline environment, better than the AISI 420 itself.

  10. Wrinkled, dual-scale structures of diamond-like carbon (DLC) for superhydrophobicity.

    Science.gov (United States)

    Rahmawan, Yudi; Moon, Myoung-Woon; Kim, Kyung-Suk; Lee, Kwang-Ryeol; Suh, Kahp-Yang

    2010-01-05

    We present a simple two-step method to fabricate dual-scale superhydrophobic surfaces by using replica molding of poly(dimethylsiloxane) (PDMS) micropillars, followed by deposition of a thin, hard coating layer of a SiO(x)-incorporated diamond-like carbon (DLC). The resulting surface consists of microscale PDMS pillars covered by nanoscale wrinkles that are induced by residual compressive stress of the DLC coating and a difference in elastic moduli between DLC and PDMS without any external stretching or thermal contraction on the PDMS substrate. We show that the surface exhibits superhydrophobic properties with a static contact angle over 160 degrees for micropillar spacing ratios (interpillar gap divided by diameter) less than 4. A transition of the wetting angle to approximately 130 degrees occurs for larger spacing ratios, changing the wetting from a Cassie-Cassie state (C(m)-C(n)) to a Wenzel-Cassie state (W(m)-C(n)), where m and n denote micro- and nanoscale roughness, respectively. The robust superhydrophobicity of the Cassie-Cassie state is attributed to stability of the Cassie state on the nanoscale wrinkle structures of the hydrophobic DLC coating, which is further explained by a simple mathematical theory on wetting states with decoupling of nano- and microscale roughness in dual scale structures.

  11. Magnetron reactively sputtered Ti-DLC coatings on HNBR rubber : The influence of substrate bias

    NARCIS (Netherlands)

    Bui, X.L.; Pei, Y.T.; Hosson, J.Th.M. De

    2008-01-01

    In this study, Ti-containing diamond-like carbon (Ti-DLC) coatings have been deposited on HNBR (hydrogenated nitrile butadiene) rubber and also on Si wafer as reference via unbalanced magnetroli reactive sputtering from a Ti target in C2H2/Ar plasma. The deposition rates of coatings on rubber and Si

  12. Microstructure and chemical bonding of DLC films deposited on ACM rubber by PACVD

    NARCIS (Netherlands)

    Martinez-Martinez, D.; Schenkel, M.; Pei, Y.T.; Sánchez-López, J.C.; Hosson, J.Th.M. De

    2011-01-01

    The microstructure and chemical bonding of DLC films prepared by plasma assisted chemical vapor deposition on acrylic rubber (ACM) are studied in this paper. The temperature variation produced by the ion impingement during plasma cleaning and subsequent film deposition was used to modify the film

  13. A FED Prototype Using Patterned DLC Thin Films as the Cathode

    Science.gov (United States)

    Li, W.; Feng, T.; Mao, D. S.; Wang, X.; Liu, X. H.; Zou, S. C.; Zhu, Y. K.; Li, Q.; Xu, J. F.; Jin, S.; Zheng, J. S.

    In our study, diamond-like-carbon (DLC) thin films were prepared by filtered arc deposition (FAD), which provided a way to deposit DLC thin films on large areas at room temperature. Glass slides coated 100nm chromium or titanium thin films were used as cathode substrates. Millions of rectangular holes with sizes of 5 × 5μm were made on the DLC films using a routine patterning process. Here a special reactive ion beam etching method was applied to etch the DLC films. The anodes of the devices were made by electrophoretic deposition. ZnO:Zn phosphor (P15) was employed, which has a broad band bluish green (centered at 490nm). Before electrophoretic deposition, the anode substrates (ITO glass slides) had been patterned into 50 anode electrodes. In order to improve the adherence of phosphor layers, the as-deposited screens were treated in Na2SiO3 solution for 24h to add additional binder. A kind of matrix-addressed diode FED prototype was designed and packaged. 50-100μm-thick glass slides were used as spacers and getters were applied to maintain the vacuum after the exhaustion. The applied DC voltage was ranged in 0-3000V and much higher current density was measured in the cathode-patterned prototypes than the unpatterned ones during the test. As a result, characters could be well displayed.

  14. Ti-doped hydrogenated diamond like carbon coating deposited by hybrid physical vapor deposition and plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Lee, Na Rae; Sle Jun, Yee; Moon, Kyoung Il; Sunyong Lee, Caroline

    2017-03-01

    Diamond-like carbon films containing titanium and hydrogen (Ti-doped DLC:H) were synthesized using a hybrid technique based on physical vapor deposition (PVD) and plasma enhanced chemical vapor deposition (PECVD). The film was deposited under a mixture of argon (Ar) and acetylene gas (C2H2). The amount of Ti in the Ti-doped DLC:H film was controlled by varying the DC power of the Ti sputtering target ranging from 0 to 240 W. The composition, microstructure, mechanical and chemical properties of Ti-doped DLC:H films with varying Ti concentrations, were investigated using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nano indentation, a ball-on-disk tribometer, a four-point probe system and dynamic anodic testing. As a result, the optimum composition of Ti in Ti-doped DLC:H film using our hybrid method was found to be a Ti content of 18 at. %, having superior electrical conductivity and high corrosion resistance, suitable for bipolar plates. Its hardness value was measured to be 25.6 GPa with a low friction factor.

  15. Formation and retention of staphylococcal biofilms on DLC and its hybrids compared to metals used as biomaterials.

    Science.gov (United States)

    Myllymaa, Katja; Levon, Jaakko; Tiainen, Veli-Matti; Myllymaa, Sami; Soininen, Antti; Korhonen, Hannu; Kaivosoja, Emilia; Lappalainen, Reijo; Konttinen, Yrjö Tapio

    2013-01-01

    Staphylococcus epidermidis and Staphylococcus aureus cause most of the implant-related infections. Antibiotic treatment often fails and cure requires surgical intervention. It was hypothesized that biomaterial coatings resistant to biofilms offer a preventive option. Physical vapour deposited diamond-like carbon (DLC) and its polytetrafluoroethylene (DLC-PTFE-h) and polydimethylsiloxane (DLC-PDMS-h) hybrids were compared to titanium (Ti), tantalum (Ta) and chromium (Cr) thin films on silicon wafers for their resistance against formation and/or retention of biofilms produced by S. epidermidis and S. aureus in vitro. Sample surfaces were characterized for surface topography, contact angle and zeta-potential, because such properties might affect the biofilm. Biofilm was stained using calcofluor white and analysed in fluorescence microscopy using morphometry. Sixteen hour incubation was selected in pilot tests; at this checkpoint Ti, Ta, Cr and DLC-PDMS-h were almost fully covered by biofilm, but DLC and DLC-PTFE-h were only partially biofilm coated by S. epidermidis (88±26%, pDLC and its PTFE hybrid offer a potential biofilm hostile surface coating for implants and medical devices. This ability to resist biofilm formation and attachment could not be explained by only one factor, but it seems to be related to a combination of various properties, with electrokinetic streaming potential and protein coating being particularly important for its outcome. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Fabrication and electrochemistry characteristics of nickel-doped diamond-like carbon film toward applications in non-enzymatic glucose detection

    Science.gov (United States)

    Liu, Chi-Wen; Chen, Wei-En; Sun, Yin Tung Albert; Lin, Chii-Ruey

    2018-04-01

    This research work focused on the fabrication of nickel-doped diamond-like carbon (DLC) films and their characteristics including of surface morphology, microstructure, and electrochemical aiming at applications in non-enzymatic glucose detection. Novel nanodiamond target was employed in unbalanced magnetron radio-frequency co-sputtering process to prepared high quality Ni-doped DLC thin film at room temperature. TEM analysis reveals a highly uniform distribution of Ni crystallites in amorphous carbon matrix with fraction ranged from 3 to 11.5 at.% which is considered as active sites for the glucose detection. Our cyclic voltammetry measurements using 0.1 M H2SO4 solution demonstrated that the as-prepared Ni-doped DLC films possess large electrochemical potential window of 2.12 V, and this was also observed to be significantly reduced at high Ni doping level owing to lower sp3 fraction. The non-enzymatic glucose detection investigation indicates that the Ni-doped DLC thin film electrode prepared under 7 W of DC sputtering power on Ni target possesses good detecting performance, high stability, and high sensitivity to glucose concentration up to 10 mM, even with the existence of uric acid and ascorbic acid. The peak current was observed to be proportional to glucose concentration and scanning rate, demonstrating highly reversibility redox process of the film electrode and glucose.

  17. Electron population uncertainty and atomic covalency

    International Nuclear Information System (INIS)

    Chesnut, D.B.

    2006-01-01

    The atoms-in-molecules (AIM) index of atomic covalency is directly related to the AIM atomic population uncertainty. The covalent bond order, delocalization index, and, therefore, the atomic covalency are maximal when electron pairs are equally shared by the atoms involved. When polarization effects are present, these measures of covalent bond character decrease. We present atomic covalences for the single- and double-heavy atom hydrides of elements of the first and second low rows of the periodic table to illustrate these effects. Some usual behavior is seen in hydrogen-bridged species due in some cases to stronger than expected multicenter bonds and in other cases to many atoms contributing to the covalency index

  18. Formation of thin DLC films on SiO{sub 2}/Si substrate using FCVAD technique

    Energy Technology Data Exchange (ETDEWEB)

    Bootkul, D. [Department of General Science, Faculty of Science, Srinakharinwirot University, Bangkok 10110 (Thailand); Thailand Centre of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Intarasiri, S., E-mail: saweat@gmail.com [Science and Technology Research Institute, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Centre of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Aramwit, C.; Tippawan, U. [Plasma and Beam Physics Research Facility (PBP), Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D. [Plasma and Beam Physics Research Facility (PBP), Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Centre of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

    2013-07-15

    Diamond-like carbon (DLC) films deposited on SiO{sub 2}/Si substrate are attractive for novel sensitive and selective chemical sensors. According to the almost never ending of size reduction, a nm-thickness layer of the film is greatly required. However, formation of such a very thin DLC film on SiO{sub 2}/Si substrate is challenging. In this experiment, DLC films were formed using our in-house Filtered Cathodic Vacuum Arc Deposition (FCVAD) facility by varying the bias voltage of 0 V, −250 V and −450 V with the arc voltage of 350 V, 450 V, 550 V, 650 V and 750 V for 10 min. Raman spectroscopy was applied for characterization of the film qualities and Transmission Electron Microscopy (TEM) was applied for cross sectional analysis. Results showed that films of thickness ranging from 10–50 nm were easily acquired depending on deposition conditions. Deconvolution of Raman spectra of these samples revealed that, when fixing the substrate bias but increasing the arc voltage from 350 to 750 V, the ratio between D-peak and G-peak intensity, namely I{sub D}/I{sub G} ratio, tended to reduce up to the arc voltage of 450 V, then increased up to the arc voltage of 650 V and finally decreased again. On the other hand, when fixing the arc voltage, the I{sub D}/I{sub G} ratio tended to decrease continuously as the increasing of bias voltage. It can be concluded that the bonding structure would evolve from a graphitic-like structure to a diamond-like structure as the substrate bias increases. Additionally, the sp{sup 3} site should be maximized at the arc voltage ∼450 V for fixed bias voltage. It is expected that, at −450 V bias and 450 V arc, sp{sup 3} fractions could be higher than 60%. However, in some cases, e.g. at low arc voltages, voids formed between the film and the amorphous SiO{sub 2} substrate. Electron energy loss spectroscopy (EELS) of the C edge across the DLC indicated that the thicker DLC film had uniform chemistry and structure, whereas the thin DLC

  19. Formation of thin DLC films on SiO2/Si substrate using FCVAD technique

    International Nuclear Information System (INIS)

    Bootkul, D.; Intarasiri, S.; Aramwit, C.; Tippawan, U.; Yu, L.D.

    2013-01-01

    Diamond-like carbon (DLC) films deposited on SiO 2 /Si substrate are attractive for novel sensitive and selective chemical sensors. According to the almost never ending of size reduction, a nm-thickness layer of the film is greatly required. However, formation of such a very thin DLC film on SiO 2 /Si substrate is challenging. In this experiment, DLC films were formed using our in-house Filtered Cathodic Vacuum Arc Deposition (FCVAD) facility by varying the bias voltage of 0 V, −250 V and −450 V with the arc voltage of 350 V, 450 V, 550 V, 650 V and 750 V for 10 min. Raman spectroscopy was applied for characterization of the film qualities and Transmission Electron Microscopy (TEM) was applied for cross sectional analysis. Results showed that films of thickness ranging from 10–50 nm were easily acquired depending on deposition conditions. Deconvolution of Raman spectra of these samples revealed that, when fixing the substrate bias but increasing the arc voltage from 350 to 750 V, the ratio between D-peak and G-peak intensity, namely I D /I G ratio, tended to reduce up to the arc voltage of 450 V, then increased up to the arc voltage of 650 V and finally decreased again. On the other hand, when fixing the arc voltage, the I D /I G ratio tended to decrease continuously as the increasing of bias voltage. It can be concluded that the bonding structure would evolve from a graphitic-like structure to a diamond-like structure as the substrate bias increases. Additionally, the sp 3 site should be maximized at the arc voltage ∼450 V for fixed bias voltage. It is expected that, at −450 V bias and 450 V arc, sp 3 fractions could be higher than 60%. However, in some cases, e.g. at low arc voltages, voids formed between the film and the amorphous SiO 2 substrate. Electron energy loss spectroscopy (EELS) of the C edge across the DLC indicated that the thicker DLC film had uniform chemistry and structure, whereas the thin DLC film showed changes in the edge shape

  20. Characterization of the corrosion behavior of an austenitic stainless steel for biomedical applications coated with Ti N, Ti CN And DLC PVD coatings

    International Nuclear Information System (INIS)

    Antunes, Renato Altobelli

    2006-01-01

    Metallic biomaterials must present a combination of properties such as corrosion resistance, biocompatibility and mechanical resistance. Austenitic stainless steels, especially AISI 316L combine these properties with the easy of fabrication at low cost. However, they are prone to corrosion in physiological solutions. Furthermore, their corrosion products may lead to infectious ou allergenic reactions in the tissues around the implant device. In the present work, coatings produced by physical vapour deposition (PVD) methods have been applied on the surface of a 316L stainless steel to increase its corrosion resistance and biocompatibility. Three thin films were tested: titanium nitride (TiN), titanium carbonitride (TiCN) and diamond-like carbon (DLC). These materials present high hardness, wear resistance and intrinsic biocompatibility that are key features when considering biomedical applications. The characterization of the electrochemical behavior of the stainless steel coated with the three different films showed that the presence of surface defects are deleterious to the corrosion resistance of the substrate. These defects were observed using scanning electron microscopy. The evolution of the electrochemical behavior of the coated steel was explained through a mechanism based on the experimental results obtained using electrochemical impedance spectroscopy. Two different passivation treatments were carried out on the stainless steel surface, either in sulfuric or nitric acid solutions, to increase its corrosion resistance. The results suggested que these treatments were not efficient, but may be modified to improve its performance. The electronic properties of the passive films of the non-passivated and passivated stainless steel were studied using the Mott-Schottky approach. The films presented a duplex character. Below the flat band potential the behavior is typical of a highly doped type-p semiconductor. Above the flat band potential is typical of a highly

  1. Dynamic covalent gels assembled from small molecules:from discrete gelators to dynamic covalent polymers

    Institute of Scientific and Technical Information of China (English)

    Jian-Yong Zhang; Li-Hua Zeng; Juan Feng

    2017-01-01

    Dynamic covalent chemistry has emerged recently to be a powerful tool to construct functional materials.This article reviews the progress in the research and development of dynamic covalent chemistry in gels assembled from small molecules.First dynamic covalent reactions used in gels are reviewed to understand the dynamic covalent bonding.Afterwards the catalogues of dynamic covalent gels are reviewed according to the nature of gelators and the interactions between gelators.Dynamic covalent bonding can be involved to form low molecular weight gelators.Low molecular weight molecules with multiple functional groups react to form dynamic covalent cross-linked polymers and act as gelators.Two catalogues of gels show different properties arising from their different structures.This review aims to illustrate the structure-property relationships of these dynamic covalent gels.

  2. Reduction in static friction by deposition of a homogeneous diamond-like carbon (DLC) coating on orthodontic brackets.

    Science.gov (United States)

    Akaike, Shun; Hayakawa, Tohru; Kobayashi, Daishiro; Aono, Yuko; Hirata, Atsushi; Hiratsuka, Masanori; Nakamura, Yoshiki

    2015-01-01

    In orthodontics, a reduction in static friction between the brackets and wire is important to enable easy tooth movement. The aim of this study was to examine the effects of a homogeneous diamond-like carbon (DLC) coating on the whole surfaces of slots in stainless steel orthodontic brackets on reducing the static friction between the brackets and the wire. The DLC coating was characterized using Raman spectroscopy, surface roughness and contact angle measurements, and SEM observations. Rectangular stainless steel and titanium-molybdenum alloy wires with two different sizes were employed, and the static friction between the brackets and wire was measured under dry and wet conditions. The DLC coating had a thickness of approximately 1.0 μm and an amorphous structure was identified. The results indicated that the DLC coating always led to a reduction in static friction.

  3. Effect of Coil Current on the Properties of Hydrogenated DLC Coatings Fabricated by Filtered Cathodic Vacuum Arc Technique

    Science.gov (United States)

    Liao, Bin; Ouyang, Xiaoping; Zhang, Xu; Wu, Xianying; Bian, Baoan; Ying, Minju; Jianwu, Liu

    2018-01-01

    We successfully prepared hydrogenated DLC (a-C:H) with a thickness higher than 25 μm on stainless steel using a filtered cathode vacuum arc (FCVA) technique. The structural and mechanical properties of DLC were systematically analyzed using different methods such as x-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, Vickers hardness, nanohardness, and friction and wear tests. The effect of coil current on the arc voltage, ion current, and mechanical properties of resultant films was systematically investigated. The novelty of this study is the fabrication of DLC with Vickers hardness higher than 1500 HV, in the meanwhile with the thickness higher than 30 μm through varying the coil current with FCVA technique. The results indicated that the ion current, deposition rate, friction coefficient, and Vickers hardness of DLC were significantly affected by the magnetic field inside the filtered duct.

  4. Study on tribological behavior and cutting performance of CVD diamond and DLC films on Co-cemented tungsten carbide substrates

    International Nuclear Information System (INIS)

    Zhang Dongcan; Shen Bin; Sun Fanghong

    2010-01-01

    The tribological behaviors of diamond and diamond-like carbon (DLC) films play a major role on their machining and mechanical applications. In this study, diamond and diamond-like carbon (DLC) films are deposited on the cobalt cemented tungsten carbide (WC-Co) substrate respectively adopting the hot filament chemical vapor deposition (HFCVD) technique and the vacuum arc discharge with a graphite cathode, and their friction properties are evaluated on a reciprocating ball-on-plate tribometer with counterfaces of silicon nitride (Si 3 N 4 ) ceramic, cemented tungsten carbide (WC) and ball-bearing steel materials, under the ambient air without lubricating condition. Moreover, to evaluate their cutting performance, comparative turning tests are conducted using the uncoated WC-Co and as-fabricated CVD diamond and DLC coated inserts, with glass fiber reinforced plastics (GFRP) composite materials as the workpiece. The as-deposited HFCVD diamond and DLC films are characterized with energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), Raman spectroscopy and 3D surface topography based on white-light interferometry. Furthermore, Rocwell C indentation tests are conducted to evaluate the adhesion of HFCVD diamond and DLC films grown onto WC-Co substrates. SEM and 3D surface topography based on white-light interferometry are also used to investigate the worn region on the surfaces of diamond and DLC films. The friction tests suggest that the obtained friction coefficient curves that of various contacts exhibit similar evolution tendency. For a given counterface, DLC films present lower stable friction coefficients than HFCVD diamond films under the same sliding conditions. The cutting tests results indicate that flank wear of the HFCVD diamond coated insert is lower than that of DLC coated insert before diamond films peeling off.

  5. Borazino-Doped Polyphenylenes.

    Science.gov (United States)

    Marinelli, Davide; Fasano, Francesco; Najjari, Btissam; Demitri, Nicola; Bonifazi, Davide

    2017-04-19

    The divergent synthesis of two series of borazino-doped polyphenylenes, in which one or more aryl units are replaced by borazine rings, is reported for the first time, taking advantage of the decarbonylative [4 + 2] Diels-Alder cycloaddition reaction between ethynyl and tetraphenylcyclopentadienone derivatives. Because of the possibility of functionalizing the borazine core with different groups on the aryl substituents at the N and B atoms of the borazino core, we have prepared borazino-doped polyphenylenes featuring different doping dosages and orientations. To achieve this, two molecular modules were prepared: a core and a branching unit. Depending on the chemical natures of the central aromatic module and the reactive group, each covalent combination of the modules yields one exclusive doping pattern. By means of this approach, three- and hexa-branched hybrid polyphenylenes featuring controlled orientations and dosages of the doping B 3 N 3 rings have been prepared. Detailed photophysical investigations showed that as the doping dosage is increased, the strong luminescent signal is progressively reduced. This suggests that the presence of the B 3 N 3 rings engages additional deactivation pathways, possibly involving excited states with an increasing charge-separated character that are restricted in the full-carbon analogues. Notably, a strong effect of the orientational doping on the fluorescence quantum yield was observed for those hybrid polyphenylene structures featuring low doping dosages. Finally, we showed that Cu-catalyzed 1,3-dipolar cycloaddition is also chemically compatible with the BN core, further endorsing the inorganic benzene as a versatile aromatic scaffold for engineering of molecular materials with tailored and exploitable optoelectronic properties.

  6. Comparative study of dlc coatings by pvd against cvd technique on textile dents

    International Nuclear Information System (INIS)

    Malik, M.; Alam, S.; Iftikhar, F.

    2007-01-01

    Diamond like Carbon (DLC) film is a hard amorphous carbon hydride film formed by Physical or Chemical vapor deposition (PVD or CVD) techniques. Due to its unique properties especially high hardness, lower coefficient of friction and lubricious nature, these coatings are not only used to extend the life of cutting tools but also for non cutting applications such as for forming dies, molds and on many functional parts of textile. In the present work two techniques were employed i.e. PVD and CVD for deposition of diamond like carbon film on textile dents. These dents are used as thread guider in high speed weaving machine. The measurement of coating thickness, adhesion, hardness and roughness values indicates that overall properties of DLC coating developed by PVD LARC technology reduces abrasion and increases the workability and durability of textile dents as well as suppress the need of lubricants. (author)

  7. Influence of residual Ar+ in Ar cluster ion beam for DLC film formation

    International Nuclear Information System (INIS)

    Kitagawa, Teruyuki; Miyauchi, Kazuya; Toyoda, Noriaki; Kanda, Kazuhiro; Ikeda, Tokumi; Tsubakino, Harushige; Matsuo, Jiro; Matsui, Shinji; Yamada, Isao

    2003-01-01

    In order to study the influences of residual Ar monomer ion (Ar + ) on sp 2 content and hardness of diamond like carbon (DLC) films formed by Ar cluster ion beam assisted deposition, Ar cluster ion, Ar + and their mixed ions (Ar cluster ion and Ar + ) bombardments were performed during evaporation of C 60 . From near edge X-ray absorption fine structure (NEXAFS) and Raman spectroscopy measurements, lower sp 2 content in the carbon films was obtained with Ar cluster ion bombardment than that with Ar + and mixed ion. Furthermore higher hardness and smooth surface were shown with Ar cluster ion bombardments. Therefore it was important to reduce Ar + in Ar cluster ion beams to obtain hard DLC films with flat surface

  8. The interaction between diamond like carbon (DLC coatings and ionic liquids under boundary lubrication conditions

    Directory of Open Access Journals (Sweden)

    K. Milewski

    2017-01-01

    Full Text Available The aim of the study was to analyse antiwear DLC coatings produced by physical vapour deposition. The a-C:H coatings were deposited on steel elements designed to operate under friction conditions. The coating structure was studied by observing the surface topography with a scanning electron microscope (SEM and a profilometer. The friction and wear properties of the coatings were examined using a ball-on-disc tribotester. The lubricants tested were two types of ionic liquids (1-butyl-3-methylimidazolium tetrafluoroborate and trihexyltetradecylphosphonium bis(trifluoromethy-lsulphonyl amide. The experimental data was used to select ionic liquids with the best tribological properties to operate under lubricated friction conditions and interact with DLC coatings.

  9. Films with discrete nano-DLC-particles as the field emission cascade

    International Nuclear Information System (INIS)

    Song Fengqi; Bu Haijun; Wan Jianguo; Wang Guanghou; Zhou Feng; He Longbing; Han Min; Zhou Jianfeng; Wang Xiaoshu

    2008-01-01

    Films with discrete diamond-like-carbon (DLC) nanoparticles were prepared by the deposition of the carbon nanoparticle beam. Their morphologies were imaged by scanning electron microscopy and atomic force microscopy (AFM). The nanoparticles were found to be distributed on the silicon (1 0 0) substrate discretely. Hemispherical shapes of the nanoparticles were demonstrated by the AFM line profile. Electron energy loss spectra were measured and an sp 3 ratio as high as 86% was found. Field-induced electron emission of the as-prepared cascade (nanoDLC/ Si) was tested and a current density of 1 mA cm -2 was achieved at 10.2 V μm -1 . (fast track communication)

  10. Preservation of plasmonic interactions in DLC protected robust organic-plasmonic hybrid systems

    DEFF Research Database (Denmark)

    Cielecki, Pawel Piotr; Sobolewska, Elżbieta Karolina; Kostiučenko, Oksana

    Gold is the most commonly used plasmonic material, however soft and prone to mechanical deformations. It has been previously shown that the durability of gold plasmonic substrates can be improved by applying a protective diamond-like carbon (DLC) coating [1]. In this work, we investigate...... the influence of such protective layers on plasmonic interactions in organic-plasmonic hybrid systems. We consider systems, consisting of 1-Cyano-quaterphenylene nanofibers on top of gold nano-square plasmonic arrays [2], coated with protective layers of varying thickness. We investigate the spectral position...... response of organic nanofibers. Subsequently, we experimentally characterize the plasmonic coupling between organic nanofibers and underlying substrates by time-resolved photoluminescence spectroscopy. Our findings reveal that the optimal thickness for DLC coating, in terms of mechanical protection while...

  11. Grey fuzzy logic approach for the optimization of DLC thin film coating process parameters using PACVD technique

    Science.gov (United States)

    Ghadai, R. K.; Das, P. P.; Shivakoti, I.; Mondal, S. C.; Swain, B. P.

    2017-07-01

    Diamond-like carbon (DLC) coatings are widely used in medical, manufacturing and aerospace industries due to their excellent mechanical, biological, optical and tribological properties. The selection of optimal process parameters for efficient characteristics of DLC film is always a challenging issue for the materials science researchers. The optimal combination of the process parameters involved in the deposition of DLC films provide a better result, which subsequently help other researchers to choose the process parameters. In the present work Grey Relation Analysis (GRA) and Fuzzy-logic are being used for the optimization of process parameters in DLC film coating by using plasma assist chemical vapour deposition (PACVD) technique. The bias voltage, bias frequency, deposition pressure, gas composition are considered as input process parameters and hardness (GPa), Young's modulus (GPa), ratio between diamond to graphic fraction, (Id/Ig) ratio are considered as response parameters. The input parameters are optimized by grey fuzzy analysis. The contribution of individual input parameter is done by ANOVA. In this analysis found that bias voltage having the least influence and gas composition has highest influence in the PACVD deposited DLC films. The grey fuzzy analysis results indicated that optimum results for bias voltage, bias frequency, deposition pressure, gas composition for the DLC thin films are -50 V, 6 kHz, 4 μbar and 60:40 % respectively.

  12. Controlled Distribution and Clustering of Silver in Ag-DLC Nanocomposite Coatings Using a Hybrid Plasma Approach.

    Science.gov (United States)

    Cloutier, M; Turgeon, S; Busby, Y; Tatoulian, M; Pireaux, J-J; Mantovani, D

    2016-08-17

    Incorporation of selected metallic elements into diamond-like carbon (DLC) has emerged as an innovative approach to add unique functional properties to DLC coatings, thus opening up a range of new potential applications in fields as diverse as sensors, tribology, and biomaterials. However, deposition by plasma techniques of metal-containing DLC coatings with well-defined structural properties and metal distribution is currently hindered by the limited understanding of their growth mechanisms. We report here a silver-incorporated diamond-like carbon coating (Ag-DLC) prepared in a hybrid plasma reactor which allowed independent control of the metal content and the carbon film structure and morphology. Morphological and chemical analyses of Ag-DLC films were performed by atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The vertical distribution of silver from the surface toward the coating bulk was found to be highly inhomogeneous due to top surface segregation and clustering of silver nanoparticles. Two plasma parameters, the sputtered Ag flux and ion energy, were shown to influence the spatial distribution of silver particles. On the basis of these findings, a mechanism for Ag-DLC growth by plasma was proposed.

  13. Bonding and bio-properties of hybrid laser/magnetron Cr-enriched DLC layers

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Miroslav; Zemek, Josef; Vandrovcová, Marta; Bačáková, Lucie; Kocourek, Tomáš; Remsa, Jan; Písařík, Petr

    2016-01-01

    Roč. 58, Jan (2016), s. 1217-1224 ISSN 0928-4931 R&D Projects: GA ČR GA15-05864S; GA MŠk(CZ) LM2011026 Institutional support: RVO:68378271 ; RVO:67985823 Keywords : DLC * chromium * hybrid PLD * hexavalent chromium * trivalent chromium * cell adhesion * cell proliferation Subject RIV: BM - Solid Matter Physics ; Magnetism; BO - Biophysics (FGU-C) Impact factor: 4.164, year: 2016

  14. CVD Diamond, DLC, and c-BN Coatings for Solid Film Lubrication

    Science.gov (United States)

    Miyoshi, Kazuhisa

    1998-01-01

    When the main criteria for judging coating performance were coefficient of friction and wear rate, which had to be less than 0.1 and 10(exp -6) mm(exp 3)/N-m, respectively, carbon- and nitrogen-ion-implanted, fine-grain CVD diamond and DLC ion beam deposited on fine-grain CVD diamond met the requirements regardless of environment (vacuum, nitrogen, and air).

  15. Effect of Structure, Composition, and Micromorphology on the Hydrophobic Property of F-DLC Film

    Directory of Open Access Journals (Sweden)

    Aihua Jiang

    2013-01-01

    Full Text Available Fluorinated diamond-like carbon (F-DLC films were prepared by radio frequency plasma-enhanced chemical vapor deposition technique with CF4 and CH4 as source gases under different deposition conditions. The chemical bonding structure and composition of the films were detected by Raman, Fourier transform infrared absorption spectrometry (FTIR, and X-ray photoelectron spectroscopy (XPS characterization. The micromorphology and surface roughness of the film were observed and analyzed by atomic force microscopy (AFM. The results indicated that all the prepared films presented a diamond-like carbon structure. The relative content of fluorine in the films increased, containing more CF2 groups. The ratio of hybrid structure sp3/sp2 decreased. The surface roughness of the films increased when the gas flow ratio R (R = CF4/[CH4 + CF4] or the deposition power increased. The contact angle of water with the surface of the F-DLC film was measured with a static drop-contact angle/surface tension measuring instrument. The hydrophobic property of the F-DLC films was found to be dependent on the sp2 structure, fluorine content, and surface roughness of the films. The contact angle increased when the relative content of fluorine in the films and sp2 content increased, whereas the contact angle first increased and then decreased with the surface roughness.

  16. Field emission properties of ring-shaped Si ridges with DLC coating

    Science.gov (United States)

    Prommesberger, Christian; Ławrowski, Robert; Langer, Christoph; Mecani, Mirgen; Huang, Yifeng; She, Juncong; Schreiner, Rupert

    2017-05-01

    We report on the fabrication and the emission characterization of single ring-shaped Si ridges with a coating of diamond-like carbon (DLC). The reactive ion etching and the subsequent inductively coupled plasma step were adjusted to realize ring-shaped Si ridges with a height of 7.5 μm respectively 15 μm and an apex radius of 20 - 25 nm. The samples were coated with a DLC layer (thickness ≈ 2 - 5 nm) by a filtered cathodic vacuum arc deposition system in order to lower the work function of the emitter and to improve the field emission characteristics. The field emission characterizations were done in diode configuration with cathode and anode separated by a 50 μm thick mica spacer. A higher emission current was carried out for the ring-shaped Si ridge in comparison to the point-shaped Si tips due to the increased emission area. The highest emission current of 0.22 μA at 1000 V was measured on a DLC-coated sample with the highest aspect ratio. No degradation of the emission current was observed in the plateau regime during a measurement period of 6 h. Finally, no decreasing performance of the field emission properties was found due to changes in the geometry or destructions.

  17. DLC and AlN thin films influence the thermal conduction of HPLED light

    Science.gov (United States)

    Hsu, Ming Seng; Hsu, Ching Yao; Huang, Jen Wei; Shyu, Feng Lin

    2015-08-01

    Thermal dissipation had an important influence in the effect and life of light emitting diodes (LED) because it enables transfer the heat away from electric device to the aluminum plate that can be used for heat removal. In the industrial processing, the quality of the thermal dissipation decides by the gumming technique between the PCB and aluminum plate. In this study, we fabricated double layer ceramic thin films of diamond like carbon (DLC) and alumina nitride (AlN) by vacuum sputtering soldered the substrate of high power light emitting diodes (HPLED) light to check the heat conduction. The ceramic dielectric coatings were characterized by several subsequent analyses, especially the measurement of real work temperature. The X-Ray photoelectron spectroscopy (XPS) patterns reveal those ceramic phases were successfully grown onto the substrate. The work temperatures show DLC and AlN films coating had limited the heat transfer by the lower thermal conductivity of these ceramic films. Obviously, it hadn't transferred heat and limited work temperature of HPLED better than DLC thin film only.

  18. Microstructure and property of diamond-like carbon films with Al and Cr co-doping deposited using a hybrid beams system

    International Nuclear Information System (INIS)

    Dai, Wei; Liu, Jingmao; Geng, Dongsen; Guo, Peng; Zheng, Jun; Wang, Qimin

    2016-01-01

    Highlights: • Diamond-like carbon films with Al and Cr doping were deposited. • Alternate multilayered structure consisted of Al-poor layer and Al-rich layer was formed. • The periodic Al-rich layers can greatly improve the residual stress and elastic resilience of the films. - Abstract: DLC films with weak carbide former Al and carbide former Cr co-doping (Al:Cr-DLC) were deposited by a hybrid beams system comprising an anode-layer linear ion beam source (LIS) and high power impulse magnetron sputtering using a gas mixture of C 2 H 2 and Ar as the precursor. The doped Al and Cr contents were controlled via adjusting the C 2 H 2 fraction in the gas mixture. The composition, microstructure, compressive stress, mechanical properties and tribological behaviors of the Al:Cr-DLC films were researched carefully using X-ray photoelectron spectroscopy, transmission electron microscopy, Raman spectroscopy, stress-tester, nanoindentation and ball-on-plate tribometer as function of the C 2 H 2 fraction. The results show that the Al and Cr contents in the films increased continuously as the C 2 H 2 fraction decreased. The doped Cr atoms preferred to bond with the carbon while the Al atoms mainly existed in metallic state. Structure modulation with alternate multilayer consisted of Al-poor DLC layer and Al-rich DLC layer was found in the films. Those periodic Al-rich DLC layers can effectively release the residual stress of the films. On the other hand, the formation of the carbide component due to Cr incorporation can help to increase the film hardness. Accordingly, the residual stress of the DLC films can be reduced without sacrificing the film hardness though co-doping Al and Cr atoms. Furthermore, it was found that the periodic Al-rich layer can greatly improve the elastic resilience of the DLC films and thus decreases the film friction coefficient and wear rate significantly. However, the existence of the carbide component would cause abrasive wear and thus

  19. Microstructure and property of diamond-like carbon films with Al and Cr co-doping deposited using a hybrid beams system

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Wei, E-mail: popdw@126.com [School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Liu, Jingmao; Geng, Dongsen [School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Guo, Peng [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Zheng, Jun [Science and Technology on Surface Engineering Laboratory, Lanzhou Institute of Physics, Lanzhou 730000 (China); Wang, Qimin, E-mail: qmwang@gdut.edu.cn [School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

    2016-12-01

    Highlights: • Diamond-like carbon films with Al and Cr doping were deposited. • Alternate multilayered structure consisted of Al-poor layer and Al-rich layer was formed. • The periodic Al-rich layers can greatly improve the residual stress and elastic resilience of the films. - Abstract: DLC films with weak carbide former Al and carbide former Cr co-doping (Al:Cr-DLC) were deposited by a hybrid beams system comprising an anode-layer linear ion beam source (LIS) and high power impulse magnetron sputtering using a gas mixture of C{sub 2}H{sub 2} and Ar as the precursor. The doped Al and Cr contents were controlled via adjusting the C{sub 2}H{sub 2} fraction in the gas mixture. The composition, microstructure, compressive stress, mechanical properties and tribological behaviors of the Al:Cr-DLC films were researched carefully using X-ray photoelectron spectroscopy, transmission electron microscopy, Raman spectroscopy, stress-tester, nanoindentation and ball-on-plate tribometer as function of the C{sub 2}H{sub 2} fraction. The results show that the Al and Cr contents in the films increased continuously as the C{sub 2}H{sub 2} fraction decreased. The doped Cr atoms preferred to bond with the carbon while the Al atoms mainly existed in metallic state. Structure modulation with alternate multilayer consisted of Al-poor DLC layer and Al-rich DLC layer was found in the films. Those periodic Al-rich DLC layers can effectively release the residual stress of the films. On the other hand, the formation of the carbide component due to Cr incorporation can help to increase the film hardness. Accordingly, the residual stress of the DLC films can be reduced without sacrificing the film hardness though co-doping Al and Cr atoms. Furthermore, it was found that the periodic Al-rich layer can greatly improve the elastic resilience of the DLC films and thus decreases the film friction coefficient and wear rate significantly. However, the existence of the carbide component would

  20. Effect of sputtering power on structure, adhesion strength and corrosion resistance of nitrogen doped diamond-like carbon thin films.

    Science.gov (United States)

    Khun, N W; Liu, E

    2011-06-01

    Nitrogen doped diamond-like carbon (DLC:N) thin films were deposited on highly conductive p-Si substrates using a DC magnetron sputtering deposition system. The DLC:N films were characterized using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), contact angle measurement and micro-scratch test. The XPS and Raman results indicated that the sputtering power significantly influenced the properties of the films in terms of bonding configuration in the films. The corrosion performance of the DLC:N films was investigated in a 0.6 M NaCl solution by means of potentiodynamic polarization testing. It was found that the corrosion performance of the films could be enhanced by higher sputtering powers.

  1. Bonding and bio-properties of hybrid laser/magnetron Cr-enriched DLC layers

    Energy Technology Data Exchange (ETDEWEB)

    Jelinek, Miroslav, E-mail: jelinek@fzu.cz [Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i, Na Slovance 2, 18221 Prague (Czech Republic); Czech Technical University in Prague, Faculty of Biomedical Engineering, nam. Sitna 3105, 27201 Kladno (Czech Republic); Zemek, Josef [Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i, Na Slovance 2, 18221 Prague (Czech Republic); Vandrovcová, Marta; Bačáková, Lucie [Institute of Physiology of the Czech Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 14220 Prague 4 (Czech Republic); Kocourek, Tomáš; Remsa, Jan; Písařík, Petr [Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i, Na Slovance 2, 18221 Prague (Czech Republic); Czech Technical University in Prague, Faculty of Biomedical Engineering, nam. Sitna 3105, 27201 Kladno (Czech Republic)

    2016-01-01

    Chromium-enriched diamond-like carbon (DLC) layers were prepared by a hybrid technology using a combination of pulsed laser deposition (PLD) and magnetron sputtering. XRD revealed no chromium peaks, indicating that the layers are mostly amorphous. Carbon (sp{sup 2} and sp{sup 3} bonds) and chromium bonds were determined by XPS from C 1s, O 1s, and Cr 2p photoelectron peaks. Depending on the deposition conditions, the concentration of Cr in DLC layers moved from zero to 10 at.% for as-received sample surfaces, and to about 31 at.% after mild sputter-cleaning by argon ion cluster beam. It should be noted that the most stable Cr{sup 3+} bonding state is in Cr{sub 2}O{sub 3} and Cr(OH){sub 3}, and that there is the toxic Cr{sup 6+} state in CrO{sub 3}. The surface content of hexavalent chromium in the Cr 2p3/2 spectra is rather low, but discernible. The population density of Saos-2 cells was the highest in samples containing higher concentrations of chromium 7.7 and 10 at.%. This means that higher concentrations of chromium supported the cell adhesion and proliferation. In addition, as revealed by a LIVE/DEAD viability/cytotoxicity kit, the cells on all Cr-containing samples maintained high viability (96 to 99%) on days 1 and 3 after seeding. However, this seemingly positive cell behavior could be associated with the risk of dedifferentiation and oncogenic transformation of cells. - Highlights: • DLC and chromium-enriched DLC layers were prepared by hybrid laser–magnetron deposition. • The content of chromium in DLC varied up to 10 at.% (31 at.% after ion beam sputtering). • The surface content of toxic hexavalent chromium in the Cr 2p3/2 spectra is rather low but discernible. • Higher concentrations of chromium supported the cell adhesion and proliferation. • Cells on all Cr-containing samples maintained high viability (96 to 99%).

  2. Hybrid laser technology and doped biomaterials

    Science.gov (United States)

    Jelínek, Miroslav; Zemek, Josef; Remsa, Jan; Mikšovský, Jan; Kocourek, Tomáš; Písařík, Petr; Trávníčková, Martina; Filová, Elena; Bačáková, Lucie

    2017-09-01

    Hybrid laser-based technologies for deposition of new types of doped thin films are presented. The focus is on arrangements combining pulsed laser deposition (PLD) with magnetron sputtering (MS), and on the setup with two simultaneously running PLD systems (dual PLD). Advantages and disadvantages of both arrangements are discussed. Layers of different dopants concentration were prepared. Experience with deposition of chromium and titanium doped diamond-like carbon (DLC) films for potential coating of bone implants is presented. Properties of the layers prepared by both technologies are compared and discussed. The suitability of the layers for colonization with human bone marrow mesenchymal stem cells and human osteoblast-like cells, were also evaluated under in vitro conditions.

  3. Tribological Performance of Hydrogenated Amorphous Carbon (a-C: H DLC Coating when Lubricated with Biodegradable Vegetal Canola Oil

    Directory of Open Access Journals (Sweden)

    H.M. Mobarak

    2014-06-01

    Full Text Available Increasing environmental awareness and demands for lowering energy consumptions are strong driving forces behind the development of the vehicles of tomorrow. Without the advances of lubricant chemistry and adequate lubricant formulation, expansion of modern engines would not have been possible. Considering environmental awareness factors as compared to mineral oils, vegetal oil based biolubricants are renewable, biodegradable, non-toxic and have a least amount of greenhouse gases. Furthermore, improvement in engine performance and transmission components, which were impossible to achieve by applying only lubricants design, is now possible through diamond like carbon (DLC coatings. DLC coatings exhibit brilliant tribological properties, such as good wear resistance and low friction. In this regard, tribological performance of a-C: H DLC coating when lubricated with Canola vegetal oil has been investigated by the help of a ball-on-flat geometry. Experimental results demonstrated that the a-C: H DLC coating exhibited better performance with Canola oil in terms of friction and wear as compared to the uncoated materials. Large amount of polar components in the Canola oil significantly improved the tribological properties of the a-C:H coating. Thus, usage of a-C: H DLC coating with Canola oil in the long run may have a positive impact on engine life.

  4. Effects of texture diameter and depth on the tribological performance of DLC coating under lubricated sliding condition

    Science.gov (United States)

    Arslan, A.; Masjuki, H. H.; Varman, M.; Kalam, M. A.; Quazi, M. M.; Al Mahmud, K. A. H.; Gulzar, M.; Habibullah, M.

    2015-11-01

    In this study, the effect of surface texturing parameters on the tribological performance of amorphous hydrogenated diamond-like carbon (DLC) under oil lubrication has been investigated. Micro dimples were created on a substrate by using a picosecond laser. After surface texturing was performed, amorphous hydrogenated diamond-like carbon (DLC) coating was deposited through magnetron sputtering. Dimple diameter varied from 50 μm to 300 μm, and dimple depth varied from 6 μm to 30 μm. Results show that at respective dimple diameter and depth of 100 μm and 6 μm, surface texturing improved the tribological performance of the amorphous hydrogenated DLC coating. Whereas, at a higher dimple diameter of 300 μm and dimple depth of 30 μm, the tribological performance of textured amorphous hydrogenated DLC was worse than that of un-textured amorphous hydrogenated DLC. The performance enhancement in the case of dimple diameter and depth of 100 μm and 6 μm can be due to micro textures, which can serve as a lubricant reservoir at the interface during sliding and remove wear particles from the contact. However, this beneficial mechanism could be obtained at an optimum texture diameter and depth.

  5. Covalent bonding in heavy metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Bagus, Paul S.; Nelin, Connie J.; Hrovat, Dave A.; Ilton, Eugene S.

    2017-04-07

    Novel theoretical methods were used to quantify the magnitude and the energetic contributions of 4f/5f-O2p and 5d/6d-O2p interactions to covalent bonding in lanthanide and actinide oxides. Although many analyses have neglected the involvement of the frontier d orbitals, the present study shows that f and d covalency are of comparable importance. Two trends are identified. As is expected, the covalent mixing is larger when the nominal oxidation state is higher. More subtly, the importance of the nf covalent mixing decreases sharply relative to (n+1)d as the nf occupation increases. Atomic properties of the metal cations that drive these trends are identified.

  6. Covalently linked bisporphyrins bearing tetraphenylporphyrin and ...

    Indian Academy of Sciences (India)

    Covalently linked bisporphyrins bearing tetraphenylporphyrin and perbromoporphyrin units: Synthesis and their properties. Puttaiah Bhyrappa V Krishnan ... yields of the TPP moiety. Electrochemical redox and fluorescence data seem to suggest the possible existence of intramolecular interactions in these bisporphyrins.

  7. 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.

  8. Thermal–Hydrodynamic Behaviour of Coated Pivoted Pad Thrust Bearings: Comparison between Babbitt, PTFE and DLC

    Directory of Open Access Journals (Sweden)

    Konstantinos Katsaros

    2018-05-01

    Full Text Available The hydrodynamic lubrication and thermal analysis of tilting pad thrust bearings has been a major subject for many studies in the field of tribology. There is only a limited number of studies regarding thrust bearings with coated surfaces. The purpose of this study is to build a parametric, iterative algorithm in order to perform a complete thermal and hydrodynamic lubrication analysis for pivoted pad thrust bearings with coatings. The analytical model is mainly based on the energy, continuity and Navier–Stokes equations, which are solved numerically with the Semi-Implicit Method for Pressure Linked Equations Consistent (SIMPLEC method. The analysis focuses on a single pivoted pad of the thrust bearing. The thermal properties of the coating material are taken into account and the resulting thermal and flow fields are solved. The basic hydrodynamic and tribological characteristics are calculated for an uncoated, a Babbitt coated, a PTFE coated and a diamond like carbon (DLC coated pivoted pad thrust bearing. The pressure and the film thickness distribution, as well as the load capacity and the frictional forces, are determined for several pad positions and velocities of the rotor. A mineral oil lubricant is used to estimate the shear thinning or thickening effects on the pad tribological performance. The results indicate that pads coated with PTFE and DLC show lower friction forces compared to the common steel and Babbitt applications. At the same time, the DLC coating seems to affect the bearing’s flow and thermal fields less than the PTFE, making it more suitable for thrust bearings applications.

  9. Tribocorrosion studies of metallic biomaterials: The effect of plasma nitriding and DLC surface modifications.

    Science.gov (United States)

    Zhao, Guo-Hua; Aune, Ragnhild E; Espallargas, Nuria

    2016-10-01

    The medical grade pure titanium, stainless steel and CoCrMo alloy have been utilized as biomaterials for load-bearing orthopedic prosthesis. The conventional surgery metals suffer from a combined effect of wear and corrosion once they are implanted, which may significantly accelerate the material degradation process. In this work, the tribocorrosion performance of the metallic biomaterials with different surface modifications was studied in the simulated body fluid for the purpose of investigating the effect of the surface treatments on the tribocorrosion performance and eventually finding the most suitable implantation materials. The metals were subjected to surface modifications by plasma nitriding in different treatment temperatures or physical vapor deposition (PVD) to produce diamond-like carbon (DLC) coating, respectively. The dry wear and tribocorrosion properties of the samples were evaluated by using a reciprocating ball-on-disc tribometer equipped with an electrochemical cell. Prior to the tribocorrosion tests, their electrochemical behavior was measured by the potentiodynamic polarization in phosphate buffer saline (PBS) solution at room temperature. Both stainless steel and CoCrMo after low temperature nitriding kept their passive nature by forming an expanded austenite phase. The DLC coated samples presented the low anodic corrosion current due to the chemical inertness of the carbon layer. During the tribocorrosion tests at open circuit potential, the untreated and low temperature nitrided samples exhibited significant potential drop towards the cathodic direction, which was a result of the worn out of the passive film. Galvanic coupling was established between the depassivated (worn) area and the still passive (unworn) area, making the materials suffered from wear-accelerated corrosion. The DLC coating performed as a solid lubricant in both dry wear and tribocorrosion tests, and the resulting wear after the tests was almost negligible. Copyright

  10. Characterisation of DLC films deposited using titanium isopropoxide (TIPOT) at different flow rates.

    Science.gov (United States)

    Said, R; Ali, N; Ghumman, C A A; Teodoro, O M N D; Ahmed, W

    2009-07-01

    In recent years, there has been growing interest in the search for advanced biomaterials for biomedical applications, such as human implants and surgical cutting tools. It is known that both carbon and titanium exhibit good biocompatibility and have been used as implants in the human body. It is highly desirable to deposit biocompatible thin films onto a range of components in order to impart biocompatibility and to minimise wear in implants. Diamond like carbon (DLC) is a good candidate material for achieving biocompatibility and low wear rates. In this study, thin films of diamond-like-carbon DLC were deposited onto stainless steel (316) substrates using C2H2, argon and titanium isopropoxide (TIPOT) precursors. Argon was used to generate the plasma in the plasma enhanced vapour deposition (PECVD) system. A critical coating feature governing the performance of the component during service is film thickness. The as-grown films were in the thickness range 90-100 nm and were found to be dependent on TIPOT flow rate. Atomic force microscopy (AFM) was used to characterise the surface roughness of the samples. As the flow rate of TIPOT increased the average roughness was found to increase in conjunction with the film thickness. Raman spectroscopy was used to investigate the chemical structure of amorphous carbon matrix. Surface tension values were calculated using contact angle measurements. In general, the trend of the surface tension results exhibited an opposite trend to that of the contact angle. The elemental composition of the samples was characterised using a VG ToF SIMS (IX23LS) instrument and X-ray photoelectron spectroscopy (XPS). Surprisingly, SIMS and XPS results showed that the DLC samples did not show evidence of titanium since no peaks representing to titanium appeared on the SIMS/XPS spectra.

  11. Chemico-physical characterisation and in vivo biocompatibility assessment of DLC-coated coronary stents.

    Science.gov (United States)

    Castellino, Micaela; Stolojan, Vlad; Virga, Alessandro; Rovere, Massimo; Cabiale, Karine; Galloni, Marco R; Tagliaferro, Alberto

    2013-01-01

    The vast majority of stent thrombosis occurs in the acute and sub-acute phases and is more common in patients with acute coronary syndromes, due to the thrombotic milieu where stent struts are positioned. Stent thrombosis is likely due to incomplete tissue coverage of metallic stents as the contact between metallic stents and blood elements may lead to platelet adhesion and trigger vessel thrombosis. If a stent is covered after 7 days, the risk that it will be found uncovered at later stages is very low (DLC) coatings, deposited by physical vapour deposition, promote rapid endothelisation of coronary stent devices, with very low platelets activation, reducing thrombotic clots. We relate these behaviours to the surface and bulk material properties of the DLC films, subjected to a comprehensive chemico-physical characterisation using several techniques (X-ray photoelectron spectroscopy, atomic force microscopy, field-emission scanning electron microscope, transmission electron microscopy combined with electron energy loss spectroscopy, Raman and dispersive X-ray spectroscopy). In vivo studies, conducted on 24 pigs, have shown complete endothelisation after 7 days, with no fibrin mesh and with only rare monocytes scattered on the endothelial layer while 30 and 180 days tests have shown reduced inflammatory activation and a complete stabilisation of the vessel healing, with a minimal neointimal proliferation. The integral and permanent DLC film coating improves haemo- and bio-compatibility and leads to an excellent early vessel healing of the stent whilst the extremely thin strut thickness reduces the amount of late neointima and consequently the risk of late restenosis. These data should translate into a reduced acute and sub-acute stent thrombosis.

  12. Cu incorporated amorphous diamond like carbon (DLC) composites: An efficient electron field emitter over a wide range of temperature

    Science.gov (United States)

    Ahmed, Sk Faruque; Alam, Md Shahbaz; Mukherjee, Nillohit

    2018-03-01

    The effect of temperature on the electron field emission properties of copper incorporated amorphous diamond like carbon (a-Cu:DLC) thin films have been reported. The a-Cu:DLC thin films have been deposited on indium tin oxide (ITO) coated glass and silicon substrate by the radio frequency sputtering process. The chemical composition of the films was investigated using X-ray photoelectron spectroscopy and the micro structure was established using high resolution transmission electron microscopy. The sp2 and sp3 bonding ratio in the a-Cu:DLC have been analyzed by the Fourier transformed infrared spectroscopy studies. The material showed excellent electron field emission properties; which was optimized by varying the copper atomic percentage and temperature of the films. It was found that the threshold field and effective emission barrier were reduced significantly by copper incorporation as well as temperature and a detailed explanation towards emission mechanism has been provided.

  13. The effect of DLC-coating deposition method on the reliability and mechanical properties of abutment's screws.

    Science.gov (United States)

    Bordin, Dimorvan; Coelho, Paulo G; Bergamo, Edmara T P; Bonfante, Estevam A; Witek, Lukasz; Del Bel Cury, Altair A

    2018-04-10

    To characterize the mechanical properties of different coating methods of DLC (diamond-like carbon) onto dental implant abutment screws, and their effect on the probability of survival (reliability). Seventy-five abutment screws were allocated into three groups according to the coating method: control (no coating); UMS - DLC applied through unbalanced magnetron sputtering; RFPA-DLC applied through radio frequency plasma-activated (n=25/group). Twelve screws (n=4) were used to determine the hardness and Young's modulus (YM). A 3D finite element model composed of titanium substrate, DLC-layer and a counterpart were constructed. The deformation (μm) and shear stress (MPa) were calculated. The remaining screws of each group were torqued into external hexagon abutments and subjected to step-stress accelerated life-testing (SSALT) (n=21/group). The probability Weibull curves and reliability (probability survival) were calculated considering the mission of 100, 150 and 200N at 50,000 and 100,000 cycles. DLC-coated experimental groups evidenced higher hardness than control (p1 indicating that fatigue contributed to failure. High reliability was depicted at a mission of 100N. At 200N a significant decrease in reliability was detected for all groups (ranging from 39% to 66%). No significant difference was observed among groups regardless of mission. Screw fracture was the chief failure mode. DLC-coating have been used to improve titanium's mechanical properties and increase the reliability of dental implant-supported restorations. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

  14. Excellent durability of DLC film on carburized steel (JIS-SCr420) under a stress of 3.0 GPa

    International Nuclear Information System (INIS)

    Yakabe, F; Kumagai, M; Kuwahara, H; Ochiai, S; Jinbo, Y; Horiuchi, T

    2008-01-01

    To improve durability of transmission gears, Diamond Like Carbon (DLC) film coated on roller was estimated as well as TiN film. These films were coated on JIS-SCr420 steel, which was carburized, quenched, and tempered. DLC and TiN films were deposited by PCVD and PVD process, respectively. These surface modified rollers were estimated by usual metallurgical methods (observation of microstructure by optical microscope, SEM, and TEM, measurement of hardness by Vickers hardness tester and nano-indentator), measurement of friction coefficient by ball-on-disk in dry atmosphere, analysis of carbon by Raman spectroscopy and hydrogen by EDRA, and lifetime of pitting by the roller-pitting test. The hardness values were 21 GPa and 26 GPa, the elasticity coefficients were 192 GPa and 336 GPa, the friction coefficients were 0.1∼0.15 and 0.5∼0.6 for DLC and TiN films, respectively. The present DLC was a typical DLC called as hydrogenated amorphous carbon (a-C: H). The hydrogen content was about 20%. The surface fatigue resistance of DLC-coated specimen had 100 times longer life than that the carburized and quenched one even under Hertzian contact stress of 3.0 GPa. TiN coated specimen was failed at 3.0 GPa by 5.17·10 5 cycles despite that the strength of the surface of the substrate was reduced due to the exposure at higher temperature in the coating process than the temperature for tempering

  15. START-GAP3/DLC3 is a GAP for RhoA and Cdc42 and is localized in focal adhesions regulating cell morphology

    International Nuclear Information System (INIS)

    Kawai, Katsuhisa; Kiyota, Minoru; Seike, Junichi; Deki, Yuko; Yagisawa, Hitoshi

    2007-01-01

    In the human genome there are three genes encoding RhoGAPs that contain the START (steroidogenic acute regulatory protein (StAR)-related lipid transfer)-domain. START-GAP3/DLC3 is a tumor suppressor gene similar to two other human START-GAPs known as DLC1 or DLC2. Although expression of START-GAP3/DLC3 inhibits the proliferation of cancer cells, its molecular function is not well understood. In this study we carried out biochemical characterization of START-GAP3/DLC3, and explored the effects of its expression on cell morphology and intracellular localization. We found that START-GAP3/DLC3 serves as a stimulator of PLCδ1 and as a GAP for both RhoA and Cdc42 in vitro. Moreover, we found that the GAP activity is responsible for morphological changes. The intracellular localization of endogenous START-GAP3/DLC3 was explored by immunocytochemistry and was revealed in focal adhesions. These results indicate that START-GAP3/DLC3 has characteristics similar to other START-GAPs and the START-GAP family seems to share common characteristics

  16. Effect of modulation periods on the microstructure and mechanical properties of DLC/TiC multilayer films deposited by filtered cathodic vacuum arc method

    International Nuclear Information System (INIS)

    Xu, Zhaoying; Sun, H.; Leng, Y.X.; Li, Xueyuan; Yang, Wenmao; Huang, N.

    2015-01-01

    Highlights: • DLC/TiC multilayer films with different modulation periods at same modulation ratio 1:1 were deposited by FCVA. • The residual stress of DLC/TiC multilayer films decreases with the modulation periods decrease. • The hardness of the multilayer DLC films decreases with modulation periods increasing. - Abstract: The high stress of diamond-like carbon (DLC) film limits its thickness and adhesion on substrate. Multilayer structure is one approach to overcome this disadvantage. In this paper, the DLC/TiC multilayer films with different modulation periods (80 nm, 106 nm or 160 nm) at same modulation ratio of 1:1 were deposited on Si(1 0 0) wafer and Ti-6Al-4V substrate by filtered cathodic vacuum arc (FCVA) technology. X-ray diffraction (XRD), transmission electron microscopy (TEM), nanoindention and wear test were employed to investigate the effect of modulation periods on the microstructure and mechanical properties of the multilayer films. The results showed that the residual stress of the DLC/TiC multilayer films could be effectively reduced and the residual stress decreased with the modulation periods decreasing. The hardness of the DLC/TiC multilayer films increased with modulation periods decreasing. The DLC/TiC multilayer film with modulation period of 106 nm had the best wear resistance due to the good combination of hardness, ductility and low compressive stress

  17. Uncovering the Rare Variants of DLC1 Isoform 1 and Their Functional Effects in a Chinese Sporadic Congenital Heart Disease Cohort

    Science.gov (United States)

    Wang, Zhen; Tan, Huilian; Kong, Xianghua; Shu, Yang; Zhang, Yuchao; Huang, Yun; Zhu, Yufei; Xu, Heng; Wang, Zhiqiang; Wang, Ping; Ning, Guang; Kong, Xiangyin; Hu, Guohong; Hu, Landian

    2014-01-01

    Congenital heart disease (CHD) is the most common birth defect affecting the structure and function of fetal hearts. Despite decades of extensive studies, the genetic mechanism of sporadic CHD remains obscure. Deleted in liver cancer 1 (DLC1) gene, encoding a GTPase-activating protein, is highly expressed in heart and essential for heart development according to the knowledge of Dlc1-deficient mice. To determine whether DLC1 is a susceptibility gene for sporadic CHD, we sequenced the coding region of DLC1 isoform 1 in 151 sporadic CHD patients and identified 13 non-synonymous rare variants (including 6 private variants) in the case cohort. Importantly, these rare variants (8/13) were enriched in the N-terminal region of the DLC1 isoform 1 protein. Seven of eight amino acids at the N-terminal variant positions were conserved among the primates. Among the 9 rare variants that were predicted as “damaging”, five were located at the N-terminal region. Ensuing in vitro functional assays showed that three private variants (Met360Lys, Glu418Lys and Asp554Val) impaired the ability of DLC1 to inhibit cell migration or altered the subcellular location of the protein compared to wild-type DLC1 isoform 1. These data suggest that DLC1 might act as a CHD-associated gene in addition to its role as a tumor suppressor in cancer. PMID:24587289

  18. Fabrication and characterization of DLC coated microdimples on hip prosthesis heads.

    Science.gov (United States)

    Choudhury, Dipankar; Ay Ching, Hee; Mamat, Azuddin Bin; Cizek, Jan; Abu Osman, Noor Azuan; Vrbka, Martin; Hartl, Martin; Krupka, Ivan

    2015-07-01

    Diamond like carbon (DLC) is applied as a thin film onto substrates to obtain desired surface properties such as increased hardness and corrosion resistance, and decreased friction and wear rate. Microdimple is an advanced surface modification technique enhancing the tribological performance. In this study, DLC coated microdimples were fabricated on hip prosthesis heads and their mechanical, material and surface properties were characterized. An Electro discharge machining (EDM) oriented microdrilling was utilized to fabricate a defined microdimple array (diameter of 300 µm, depth of 70 µm, and pitch of 900 µm) on stainless steel (SS) hip prosthesis heads. The dimpled surfaces were then coated by hydrogenated amorphous carbon (a-C:H) and tetrahedral amorphous carbon (Ta-C) layers by using a magnetron sputtering technology. A preliminary tribology test was conducted on these fabricated surfaces against a ceramic ball in simulated hip joint conditions. It was found that the fabricated dimples were perpendicular to the spherical surfaces and no cutting-tools wear debris was detected inside the individual dimples. The a-C:H and Ta-C coatings increased the hardness at both the dimple edges and the nondimpled region. The tribology test showed a significant reduction in friction coefficient for coated surfaces regardless of microdimple arrays: the lowest friction coefficient was found for the a-C:H samples (µ = 0.084), followed by Ta-C (µ = 0.119), as compared to the SS surface (µ = 0.248). © 2014 Wiley Periodicals, Inc.

  19. Nm-scale diamond-like-carbon (DLC) templates for use in soft lithography

    International Nuclear Information System (INIS)

    Watson, G.S.; Myhra, S.; Brown, C.L.; Watson, J.A.

    2005-01-01

    An emerging set of methods known collectively as soft lithography is now being utilised for a large variety of applications including micromolding, microfluidic networks and microcontact printing. In particular stamps and elastomeric elements can be formed by exposure of a polymer to a template. Established lithographic techniques used in the microelectronic industry, such as photolithography, are generally used to fabricate such master templates at the micron scale. In this study we demonstrate the use of diamond-like-carbon (DLC) as a template for producing polymer micro/nano stamps and 3D polymer structures. Intricate surface relief patterns can be formed on the DLC surface from lithographic techniques by atomic force microscopy (AFM) operated in the electrical conductivity mode. A number of polymers can be used to transfer patterns. One of the most widely used polymers for pattern transfer has been polydimethylsiloxane (PDMS). The elastomer is chemically resistant, has a low surface energy and readily conforms to different surface topographies. Obtaining a master is the limiting factor in the production of PDMS replicas. (author). 2 refs., 4 figs

  20. Sealing of hard CrN and DLC coatings with atomic layer deposition.

    Science.gov (United States)

    Härkönen, Emma; Kolev, Ivan; Díaz, Belén; Swiatowska, Jolanta; Maurice, Vincent; Seyeux, Antoine; Marcus, Philippe; Fenker, Martin; Toth, Lajos; Radnoczi, György; Vehkamäki, Marko; Ritala, Mikko

    2014-02-12

    Atomic layer deposition (ALD) is a thin film deposition technique that is based on alternating and saturating surface reactions of two or more gaseous precursors. The excellent conformality of ALD thin films can be exploited for sealing defects in coatings made by other techniques. Here the corrosion protection properties of hard CrN and diamond-like carbon (DLC) coatings on low alloy steel were improved by ALD sealing with 50 nm thick layers consisting of Al2O3 and Ta2O5 nanolaminates or mixtures. In cross sectional images the ALD layers were found to follow the surface morphology of the CrN coatings uniformly. Furthermore, ALD growth into the pinholes of the CrN coating was verified. In electrochemical measurements the ALD sealing was found to decrease the current density of the CrN coated steel by over 2 orders of magnitude. The neutral salt spray (NSS) durability was also improved: on the best samples the appearance of corrosion spots was delayed from 2 to 168 h. On DLC coatings the adhesion of the ALD sealing layers was weaker, but still clear improvement in NSS durability was achieved indicating sealing of the pinholes.

  1. Adsorption of alcohols and fatty acids onto hydrogenated (a-C:H) DLC coatings

    Science.gov (United States)

    Simič, R.; Kalin, M.; Kovač, J.; Jakša, G.

    2016-02-01

    Information about the interactions between lubricants and DLC coatings is scarce, despite there having been many studies over the years. In this investigation we used ToF-SIMS, XPS and contact-angle analyses to examine the adsorption ability and mechanisms with respect to two oiliness additives, i.e., hexadecanol and hexadecanoic acid, on an a-C:H coating. In addition, we analyzed the resistance of the adsorbed films to external influences like solvent cleaning. The results show that both molecules adsorb onto surface oxides and hydroxides present on the initial DLC surface and shield these structures with their hydrocarbon tails. This makes the surfaces less polar, which is manifested in a smaller polar component of the surface energy. We also showed that ultrasonic cleaning in heptane has no significant effect on the quantity of adsorbed molecules or on their chemical state. This not only shows the relatively strong adsorption of these molecules, but also provides useful information for future experimental work. Of the two examined molecules, the acid showed a greater adsorption ability than the alcohol, which explains some of the previously reported better tribological properties in the case of the acid with respect to the alcohol.

  2. A novel tribological study on DLC-coated micro-dimpled orthopedics implant interface.

    Science.gov (United States)

    Choudhury, Dipankar; Urban, Filip; Vrbka, Martin; Hartl, Martin; Krupka, Ivan

    2015-05-01

    This study investigates a tribological performance of diamond like carbon (DLC) coated micro dimpled prosthesis heads against ceramic cups in a novel pendulum hip joint simulator. The simulator enables determining friction coefficient and viscous effects of a concave shaped specimen interface (conformal contact). Two types of DLC such as hydrogenated amorphous carbon (a-C:H) and tetrahedral amorphous carbon (Ta-C) and one set of micro dimple (diameter of 300µm, depth of 70µm, and pitch of 900µm) were fabricated on metallic prosthesis heads. The experiment results reveal a significant friction coefficient reduction to the 'dimpled a-C:H/ceramic' prosthesis compared to a 'Metal (CoCr)/ceramic' prosthesis because of their improved material and surface properties and viscous effect. The post-experiment surface analysis displays that the dimpled a-C:H yielded a minor change in the surface roughness, and generated a larger sizes of wear debris (40-200nm sized, equivalent diameter), a size which could be certainly stored in the dimple, thus likely to reducing their possible third body abrasive wear rate. Thus, dimpled a:C-H can be used as a 'metal on ceramic hip joint interface', whereas the simulator can be utilized as an advanced bio-tribometer. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. ZZ DLC-11 RITTS, 121-Group Coupled Cross-Section for ANISN, DOT, MORSE

    International Nuclear Information System (INIS)

    1970-01-01

    A - Nature of physical problem solved: Format: ANISN, DTF-4, DOT and MORSE. Number of groups: 100 neutron energy groups (14.92 MeV to thermal) 21 gamma-ray energy groups (14.0 to 0.01 MeV) Nuclides: H, C, O, N, Na, Mg, P, S, Cl, K, and Ca, (microscopic cross sections) and 9 organic materials including 11-element standard man, 4-element standard man, skin, bone, tissue, brain, lung, red marrow, and muscle (macroscopic cross sections). Origin: ENDF/B for H, C, N, O, Na, and Mg; O5R library for Ca, S, and K; GAM-2 library for Cl; Evaluation by J.J. Ritts for P. Weighting spectrum: 1/E for the top 99 groups and Maxwellian for the thermal group values. DLC-11 data is suitable for neutron, gamma-ray, or coupled neutron and gamma-ray transport calculations. It is intended for use in multigroup discrete ordinates or Monte Carlo transport codes which treat anisotropic scattering by Legendre expansion up to order P3. DLC-11 is a collection of multigroup cross section data which were compiled by J. J. Ritts for use in depth-dose calculations in anthropomorphic phantoms. For convenience the data are grouped as follows - 1. A coupled 121-group (100 neutron, 21 gamma-ray) set of data for the 11 elements H, C, O, N. Na, Mg, P, S, Cl, K, and Ca. This set includes P3 coupled 121-group microscopic cross sections plus 121-group kerma factors for the 11 elements. 2. A 100-group set of neutron cross sections for the 11 elements. 3. A coupled 121-group set of macroscopic cross sections for 9 organic materials including 11-element standard man, 4-element standard man, skin, bone, tissue, brain, lung, red marrow, and muscle. B - Method of solution: The basic data sources were ENDF/B for H, C, N, O, Na, and Mg, the O5R library for Ca, S, and K, the GAM-2 library for Cl and an evaluation by Ritts for P. A 1/E spectrum was assumed for averaging the top 99 groups and a Maxwellian for averaging the thermal group values. The gamma-ray cross sections were computed from DLC-3/HPIC using MUG. The

  4. CovalentDock Cloud: a web server for automated covalent docking.

    Science.gov (United States)

    Ouyang, Xuchang; Zhou, Shuo; Ge, Zemei; Li, Runtao; Kwoh, Chee Keong

    2013-07-01

    Covalent binding is an important mechanism for many drugs to gain its function. We developed a computational algorithm to model this chemical event and extended it to a web server, the CovalentDock Cloud, to make it accessible directly online without any local installation and configuration. It provides a simple yet user-friendly web interface to perform covalent docking experiments and analysis online. The web server accepts the structures of both the ligand and the receptor uploaded by the user or retrieved from online databases with valid access id. It identifies the potential covalent binding patterns, carries out the covalent docking experiments and provides visualization of the result for user analysis. This web server is free and open to all users at http://docking.sce.ntu.edu.sg/.

  5. Investigation of structure, adhesion strength, wear performance and corrosion behavior of platinum/ruthenium/nitrogen doped diamond-like carbon thin films with respect to film thickness

    International Nuclear Information System (INIS)

    Khun, N.W.; Liu, E.

    2011-01-01

    Research highlights: → Sputtered PtRuN-DLC thin films were fabricated with different film thicknesses. → The graphitization of the films increased with increased film thickness. → The wear resistance of the films increased though their adhesion strength decreased. → The corrosion potentials of the films shifted to more negative values. → However, the corrosion currents of the films decreased. - Abstract: In this study, the corrosion performance of platinum/ruthenium/nitrogen doped diamond-like carbon (PtRuN-DLC) thin films deposited on p-Si substrates using a DC magnetron sputtering deposition system in a 0.1 M NaCl solution was investigated using potentiodynamic polarization test in terms of film thickness. The effect of the film thickness on the chemical composition, bonding structure, surface morphology, adhesion strength and wear resistance of the PtRuN-DLC films was studied using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), micro-scratch test and ball-on-disc tribotest, respectively. It was found that the wear resistance of the PtRuN-DLC films apparently increased with increased film thickness though the adhesion strength of the films decreased. The corrosion results revealed that the increased concentration of sp 2 bonds in the PtRuN-DLC films with increased film thickness shifted the corrosion potentials of the films to more negative values but the decreased porosity density in the films significantly decreased the corrosion currents of the films.

  6. Effect of tetramethylsilane flow on the deposition and tribological behaviors of silicon doped diamond-like carbon rubbed against poly(oxymethylene)

    Science.gov (United States)

    Deng, Xingrui; Lim, Yankuang; Kousaka, Hiroyuki; Tokoroyama, Takayuki; Umehara, Noritsugu

    2014-11-01

    In this study, silicon doped diamond-like carbon (Si-DLC) was deposited on stainless steel (JIS SUS304) by using surface wave-excited plasma (SWP). The effects of tetramethylsilane (TMS) flow on the composition, topography, mechanical properties and tribological behavior were investigated. Pin-on-disc tribo-meter was used to investigate the tribological behavior of the Si-DLC coating rubbed against poly(oxymethylene) (POM). The results show that the deposition rate, roughness of Si-DLC increased and the hardness of Si-DLC decreased with the increase of TMS flow rate from 2 to 4 sccm; the roughness increase therein led to the increase of ploughing term of friction. The increase of adhesion term was also seen with the increase of TMS flow rate, being attributed to the decrease of hydrogen concentration in the coating. It was considered that more POM transferred onto the Si-DLC deposited at higher TMS flow rate due to larger heat generation by friction.

  7. Friction and wear behaviour of Mo-W doped carbon-based coating during boundary lubricated sliding

    Science.gov (United States)

    Hovsepian, Papken Eh.; Mandal, Paranjayee; Ehiasarian, Arutiun P.; Sáfrán, G.; Tietema, R.; Doerwald, D.

    2016-03-01

    A molybdenum and tungsten doped carbon-based coating (Mo-W-C) was developed in order to provide low friction in boundary lubricated sliding condition at ambient and at high temperature. The Mo-W-C coating showed the lowest friction coefficient among a number of commercially available state-of-the-art DLC coatings at ambient temperature. At elevated temperature (200 °C), Mo-W-C coating showed a significant reduction in friction coefficient with sliding distance in contrast to DLC coatings. Raman spectroscopy revealed the importance of combined Mo and W doping for achieving low friction at both ambient and high temperature. The significant decrease in friction and wear rate was attributed to the presence of graphitic carbon debris (from coating) and 'in situ' formed metal sulphides (WS2 and MoS2, where metals were supplied from coating and sulphur from engine oil) in the transfer layer.

  8. The influence of the structures and compounds of DLC coatings on the barrier properties of PET bottles

    International Nuclear Information System (INIS)

    Li, Yang; Zhen-Duo, Wang; Shou-Ye, Zhang; Li-Zhen, Yang; Qiang, Chen

    2009-01-01

    To reduce the oxygen transmission rate through a polyethylene terephthalate (PET) bottle (an organic plastic) diamond-like carbon (DLC) coatings on the inner surface of the PET bottle were deposited by radio frequency plasma-enhanced chemical vapour deposition (RF-PECVD) technology with C 2 H 2 as the source of carbon and Ar as the diluted gas. As the barrier layer to humidity and gas permeation, this paper analyses the DLC film structure, composition, morphology and barrier properties by Fourier transform infrared, atomic force microscopy, scanning electron microscopy and oxygen transmission rate in detail. From the spectrum, it is found that the DLC film mainly consists of sp 3 bonds. The barrier property of the films is significantly relevant to the sp 3 bond concentration in the coating, the film thickness and morphology. Additionally, it is found that DLC film deposited in an inductively coupled plasma enhanced capacitively coupled plasma source shows a compact, homogeneous and crack-free surface, which is beneficial for a good gas barrier property in PET bottles. (fluids, plasmas and electric discharges)

  9. INFLUENCE OF PLASMA NITRIDING ON THE CORROSION BEHAVIOUR AND ADHESION OF DLC COATINGS DEPOSITED ON AISI 420 STAINLESS STEEL

    Directory of Open Access Journals (Sweden)

    Jorge N. Pecina

    2016-06-01

    Full Text Available In this work the corrosion behavior and adhesion of two DLC (“Diamond Like Carbon” films (“Soft” and “Hard” were studied. Both coatings were deposited by PACVD (“Plasma Assisted Chemical Vapour Deposition” on plasma-nitrided and non-nitrided AISI 420 stainless steel. Raman spectroscopy was conducted and surface hardness was measured. The microstructure by OM and SEM, was observed. Adhesion tests were performed with C. Rockwell indentation test. Salt Spray and immersion were performed in HCl. The “Soft” coating was 20 μm thick, the “Hard” film was about 2.5 μm. The hardness was of 500 HV in the “Soft” DLC and 1400 HV in the “Hard” DLC. Both coatings presented low friction coefficient and good adhesion when they were deposited on nitrided steel. Also presented good resistance to atmospheric corrosion. HCl DLC degradation slowed rapidly introduced uncoated samples.

  10. The Influence of Chemical Alloying on the High Temperature Wear Resistance of H-Free DLC Coatings

    NARCIS (Netherlands)

    Galvan, D.; Pei, Y.T.; Hosson, J.T.M. De; Cavaleiro, A.; Chandra, T; Tsuzaki, K; Militzer, M; Ravindran, C

    2007-01-01

    A commercial RF-sputtering deposition rig was employed to deposit H-free diamond-like carbon (DLC) coatings. The influence of alloying elements such as Ti and Si on the structure, mechanical and tribological properties of the coatings was investigated. The coating was observed in cross section and

  11. Surface interactions of a W-DLC-coated biomedical AISI 316L stainless steel in physiological solution.

    Science.gov (United States)

    Antunes, Renato A; de Lima, Nelson Batista; Rizzutto, Márcia de Almeida; Higa, Olga Zazuco; Saiki, Mitiko; Costa, Isolda

    2013-04-01

    The corrosion stability of a W-DLC coated surgical AISI 316L stainless steel in Hanks' solution has been evaluated. Particle induced X-ray emission (PIXE) measurements were performed to evaluate the incorporation of potentially bioactive elements from the physiological solution. The film structure was analyzed by X-ray diffractometry and micro-Raman spectroscopy. The wear behavior was assessed using the sphere-on-disc geometry. The in vitro biocompatibility of the W-DLC film was evaluated by cytotoxicity tests. The corrosion resistance of the stainless steel substrate decreased in the presence of the PVD layer. EIS measurements suggest that this behavior was closely related to the corrosion attack through the coating pores. PIXE measurements revealed the presence of Ca and P in the W-DLC film after immersion in Hanks' solution. This result shows that the PIXE technique can be applied to identify and evaluate the incorporation of bioactive elements by W-DLC films. The film showed good wear resistance and biocompatibility.

  12. Tribological performance of an H-DLC coating prepared by PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Solis, J., E-mail: jsolis@ittla.edu.mx [IFS, University of Leeds, School of Mechanical Engineering, Leeds, LS2 9JT (United Kingdom); SEP/SES/TecNM/IT de Tlalnepantla, DEPI-Mechanical Engineering, 54070, Edo. Méx. (Mexico); Zhao, H.; Wang, C. [IFS, University of Leeds, School of Mechanical Engineering, Leeds, LS2 9JT (United Kingdom); Verduzco, J.A. [Instituto de Investigación en Metalurgia y Materiales, UMSNH, P.O. Box 888, 58000, Morelia, Mich. (Mexico); Bueno, A.S. [IFS, University of Leeds, School of Mechanical Engineering, Leeds, LS2 9JT (United Kingdom); Mechanical Engineering Department, Universidade Federal de São João Del Rei, 170 Praça Frei Orlando, 36307-352 São João Del Rei (Brazil); Neville, A. [IFS, University of Leeds, School of Mechanical Engineering, Leeds, LS2 9JT (United Kingdom)

    2016-10-15

    Highlights: • Duplex hydrogenated Diamond-like Carbon was produced and characterised. • Friction and wear under dry condition of H-DLC/steel tribopair was assessed. • Adhesive strength of the coating was 80N after the scratch tests under dry condition. • Maximum and minimum values of average coefficient of friction were 0.21 and 0.13. • A protective transferred layer on the counterpart produced a carbon-carbon contact. - Abstract: Carbon-based coatings are of wide interest due to their application in machine elements subjected to continuous contact where fluid lubricant films are not permitted. This paper describes the tribological performance under dry conditions of duplex layered H-DLC coating sequentially deposited by microwave excited plasma enhanced chemical vapour deposition on AISI 52100 steel. The architecture of the coating comprised Cr, WC, and DLC (a-C:H) with a total thickness of 2.8 μm and compressive residual stress very close to 1 GPa. Surface hardness was approximately 22 GPa and its reduced elastic modulus around 180 GPa. Scratch tests indicated a well adhered coating achieving a critical load of 80 N. The effect of normal load on the friction and wear behaviours were investigated with steel pins sliding against the actual coating under dry conditions at room temperature (20 ± 2 °C) and 35–50% RH. The results show that coefficient of friction of the coating decreased from 0.21 to 0.13 values with the increase in the applied loads (10–50 N). Specific wear rates of the surface coating also decrease with the increase in the same range of applied loads. Maximum and minimum values were 14 × 10{sup −8} and 5.5 × 10{sup −8} mm{sup −3}/N m, respectively. Through Raman spectroscopy and electron microscopy it was confirmed the carbon-carbon contact, due to the tribolayer formation on the wear scars of the coating and pin. In order to further corroborate the experimental observations regarding the graphitisation behaviour, the

  13. A comparative study of tribological characteristics of hydrogenated DLC film sliding against ceramic mating materials for helium applications

    Science.gov (United States)

    Wu, Daheng; Ren, Siming; Pu, Jibin; Lu, Zhibin; Zhang, Guangan; Wang, Liping

    2018-05-01

    The tribological behaviors of hydrogenated DLC film sliding against Al2O3, ZrO2, Si3N4 and WC mating balls have been comparatively investigated by a ball-on-disk tribometer at 150 °C under helium and air (RH = 6%) conditions. The results showed that the mating material influenced the friction and wear behavior remarkably in helium atmosphere, where the wear rates were in inversely proportional to the friction coefficients (COF) of those tribo-pairs. Compared to the tests in helium, the tribological performance of DLC film significantly improved in air. Scanning electron microscope (SEM) and Raman spectroscopy were performed to study the friction behavior and wear mechanism of the film under different conditions. It suggested that the severe abrasion was caused by the strong interaction between the tribo-pairs in helium atmosphere at 150 °C, whereas the sufficient passivation of the dangling bonds of carbon atoms at sliding interface by chemically active molecules, such as water and oxygen, dominated the ultralow friction under air condition. Meanwhile, Hertz analysis was used to further elucidate the frictional mechanism of DLC film under helium and air conditions. It showed that the coefficient of friction was consistent with the varied tendency of the contact radius, namely, higher friction coefficient corresponded to the larger contact radius, which was the same with the relationship between the wear rate and the contact pressure. All of the results made better understanding of the essential mechanism of hydrogenated DLC film sliding against different pairs, which were able to guide the further application of DLC film in the industrial fields of helium atmosphere.

  14. Covalent biofunctionalization of silicon nitride surfaces

    NARCIS (Netherlands)

    Arafat, A.; Giesbers, M.; Rosso, M.; Sudhölter, E.J.R.; Schroën, C.G.P.H.; White, R.G.; Li Yang,; Linford, M.R.; Zuilhof, H.

    2007-01-01

    Covalently attached organic monolayers on etched silicon nitride (SixN4; x 3) surfaces were prepared by reaction of SixN4-coated wafers with neat or solutions of 1-alkenes and 1-alkynes in refluxing mesitylene. The surface modification was monitored by measurement of the static water contact angle,

  15. Preparation and properties of DLC/MoS2 multilayer coatings for high humidity tribology

    Science.gov (United States)

    Zhao, Xiaoyu; Lu, Zhibin; Wu, Guizhi; Zhang, Guangan; Wang, Liping; Xue, Qunji

    2016-06-01

    The DLC/MoS2 multilayer coatings with different modulus ratios were deposited by magnetron sputtering in this study. The morphology, structure, composition, mechanical properties and tribological properties were investigated using several analytical techniques (FESEM, AFM, TEM, AES, XPS, nanoindentation and high humidity tribological test). The results showed that the well-defined multilayer coatings were composed of densely packed particles in which many nanocrystallines with some kinds of defects were distributed in matrix. The incorporation of oxygen into the lattice led to the degraded chemical stability. The coating’s hardness and elastic modulus were almost in the same range. Moderate improvement on the high humidity tribological properties were obtained, which was important for the extension of the service life of MoS2 in humid air.

  16. Investigation of spectral characteristics of tunnel photodiodes based on DLC nanofilms

    Science.gov (United States)

    Akchurin, Garif G.; Aban'shin, Nickolay P.; Avetisyan, Yuri A.; Akchurin, Georgy G.; Kochubey, Vyacheslav I.; Yakunin, Alexander N.

    2018-04-01

    The tunneling photo effect has been studied in a microdiode with an electrostatic field localized at an emitter based on a nanosized DLC structure. It is established the photocurrent, when the carbon nanoemitter is exposed by laser and tunable low-coherent radiation in the spectral range from UV to near IR with photons of low energy (below work function). A linear dependence of the photocurrent on the level of optical power in the range of micro- and milliwatt power is established. The effect of saturation of the current-voltage characteristics of the tunnel photocurrent associated with a finite concentration of non-equilibrium photoelectrons is observed. The observed spectral Watt-Amper characteristics can be adequately interpreted using a modified Fowler-Nordheim equation for non-equilibrium photoelectrons.

  17. Tribological performance of an H-DLC coating prepared by PECVD

    Science.gov (United States)

    Solis, J.; Zhao, H.; Wang, C.; Verduzco, J. A.; Bueno, A. S.; Neville, A.

    2016-10-01

    Carbon-based coatings are of wide interest due to their application in machine elements subjected to continuous contact where fluid lubricant films are not permitted. This paper describes the tribological performance under dry conditions of duplex layered H-DLC coating sequentially deposited by microwave excited plasma enhanced chemical vapour deposition on AISI 52100 steel. The architecture of the coating comprised Cr, WC, and DLC (a-C:H) with a total thickness of 2.8 μm and compressive residual stress very close to 1 GPa. Surface hardness was approximately 22 GPa and its reduced elastic modulus around 180 GPa. Scratch tests indicated a well adhered coating achieving a critical load of 80 N. The effect of normal load on the friction and wear behaviours were investigated with steel pins sliding against the actual coating under dry conditions at room temperature (20 ± 2 °C) and 35-50% RH. The results show that coefficient of friction of the coating decreased from 0.21 to 0.13 values with the increase in the applied loads (10-50 N). Specific wear rates of the surface coating also decrease with the increase in the same range of applied loads. Maximum and minimum values were 14 × 10-8 and 5.5 × 10-8 mm-3/N m, respectively. Through Raman spectroscopy and electron microscopy it was confirmed the carbon-carbon contact, due to the tribolayer formation on the wear scars of the coating and pin. In order to further corroborate the experimental observations regarding the graphitisation behaviour, the existing mathematical relationships to determine the graphitisation temperature of the coating/steel contact as well as the flash temperature were used.

  18. Origin of the high p-doping in F intercalated graphene on SiC

    KAUST Repository

    Cheng, Yingchun; Kaloni, T. P.; Huang, G. S.; Schwingenschlö gl, Udo

    2011-01-01

    and the SiC, which restores the Dirac point in the band structure. Second, saturation of the topmost Si dangling bonds introduces p-doping up to 0.37 eV. Third, F atoms bond covalently to the graphene to enhance the p-doping. Our model explains the highly p

  19. Covalent functionalization of graphene with reactive intermediates.

    Science.gov (United States)

    Park, Jaehyeung; Yan, Mingdi

    2013-01-15

    Graphene, a material made exclusively of sp(2) carbon atoms with its π electrons delocalized over the entire 2D network, is somewhat chemically inert. Covalent functionalization can enhance graphene's properties including opening its band gap, tuning conductivity, and improving solubility and stability. Covalent functionalization of pristine graphene typically requires reactive species that can form covalent adducts with the sp(2) carbon structures in graphene. In this Account, we describe graphene functionalization reactions using reactive intermediates of radicals, nitrenes, carbenes, and arynes. These reactive species covalently modify graphene through free radical addition, CH insertion, or cycloaddition reactions. Free radical additions are among the most common reaction, and these radicals can be generated from diazonium salts and benzoyl peroxide. Electron transfer from graphene to aryl diazonium ion or photoactivation of benzoyl peroxide yields aryl radicals that subsequently add to graphene to form covalent adducts. Nitrenes, electron-deficient species generated by thermal or photochemical activation of organic azides, can functionalize graphene very efficiently. Because perfluorophenyl nitrenes show enhanced bimolecular reactions compared with alkyl or phenyl nitrenes, perfluorophenyl azides are especially effective. Carbenes are used less frequently than nitrenes, but they undergo CH insertion and C═C cycloaddition reactions with graphene. In addition, arynes can serve as a dienophile in a Diels-Alder type reaction with graphene. Further study is needed to understand and exploit the chemistry of graphene. The generation of highly reactive intermediates in these reactions leads to side products that complicate the product composition and analysis. Fundamental questions remain about the reactivity and regioselectivity of graphene. The differences in the basal plane and the undercoordinated edges of graphene and the zigzag versus arm-chair configurations

  20. Influence of sulfidation treatment on the structure and tribological properties of nitrogen-doped diamond-like carbon films

    International Nuclear Information System (INIS)

    Zeng Qunfeng; Dong Guangneng; Xie Youbai

    2008-01-01

    The nitrogen-doped diamond-like carbon (DLC) films were deposited on high speed steel (HSS) substrates in the direct current unbalanced magnetron sputtering system. Sulphurized layer was formed on the surface of DLC films by means of liquid sulfidation in the intermixture of urea and thiourea solution in order to improve the tribological properties of DLC films. The influence of sulfidation treatment on the structure and tribological properties of DLC films was investigated in this work. The structure and wear surface morphology of DLC films were analyzed by Raman spectroscopy, XPS and SEM, respectively. It reveals that the treated films are smooth and uniform; and sulfur atoms are bonded chemically. The treated films have broader distribution of Raman spectra in the range of 1000-1800 cm -1 and higher I D /I G ratio than the untreated films as a result of the appearance of the crystalline graphite structure after the sulfidation treatment. It is showed that the sp 2 relative content increase in the treated films from the XPS measurement. The Raman results are consistent with the XPS results. The tribological properties of DLC films were investigated using a ball-on-disk rotating friction and wear tester under dry friction conditions. It is found that the sulfidation concentration plays an important part in the tribological properties of the treated DLC films. The results showed the treated films with low sulfidation concentration have a lower friction coefficient (0.1) than the treated films with high sulfidation concentration (0.26) and the untreated films (0.27) under the same friction testing conditions, which can be attributed to both the presence of sulfur-containing materials and the forming of the mechanical alloyed layer on the wear surface. Adding the dry nitrogen to the sliding surface in the testing system helps the friction coefficient of the treated films with low sulfidation concentration to decrease to 0.04 further in this work. On the basis of the

  1. Scanning tunneling spectroscopy of CdSe nanocrystals covalently bound to GaAs

    DEFF Research Database (Denmark)

    Walzer, K.; Marx, E.; Greenham, N.C.

    2003-01-01

    We present scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) measurements of CdSe nanocrystals covalently attached to doped GaAs substrates using monolayers of 1,6-hexanedithiol. STM measurements showed the formation of stable, densely packed, homogeneous monolayers...... of nanocrystals. STS measurements showed rectifying behaviour, with high currents at the opposite sample bias to that previously observed for CdSe nanocrystals adsorbed on Si substrates. We explain the rectifying behaviour by considering the interaction between the electronic states of the nanocrystals...

  2. Stress reduction of Cu-doped diamond-like carbon films from ab initio calculations

    Directory of Open Access Journals (Sweden)

    Xiaowei Li

    2015-01-01

    Full Text Available Structure and properties of Cu-doped diamond-like carbon films (DLC were investigated using ab initio calculations. The effect of Cu concentrations (1.56∼7.81 at.% on atomic bond structure was mainly analyzed to clarify the residual stress reduction mechanism. Results showed that with introducing Cu into DLC films, the residual compressive stress decreased firstly and then increased for each case with the obvious deterioration of mechanical properties, which was in agreement with the experimental results. Structural analysis revealed that the weak Cu-C bond and the relaxation of both the distorted bond angles and bond lengths accounted for the significant reduction of residual compressive stress, while at the higher Cu concentration the increase of residual stress attributed to the existence of distorted Cu-C structures and the increased fraction of distorted C-C bond lengths.

  3. Structure, adhesive strength and electrochemical performance of nitrogen doped diamond-like carbon thin films deposited via DC magnetron sputtering.

    Science.gov (United States)

    Khun, N W; Liu, E; Krishna, M D

    2010-07-01

    Nitrogen doped diamond-like carbon (DLC:N) thin films were deposited on p-Si (100) substrates by DC magnetron sputtering with different nitrogen flow rates at a substrate temperature of about 100 degrees C. The chemical bonding structure of the films was characterized by X-ray photoelectron spectroscopy (XPS) and micro-Raman spectroscopy. The adhesive strength and surface morphology of the films were studied using micro-scratch tester and scanning electron microscope (SEM), respectively. The electrochemical performance of the films was evaluated by potentiodynamic polarization testing and linear sweep voltammetry. The electrolytes used for the electrochemical tests were deaerated and unstirred 0.47 M KCl aqueous solution for potentiodynamic polarization testing and 0.2 M KOH and 0.1 M KCl solutions for voltammetric analysis. It was found that the DLC:N films could well passivate the underlying substrates though the corrosion resistance of the films decreased with increased nitrogen content in the films. The DLC:N films showed wide potential windows in the KOH solution, in which the detection ability of the DLC:N films to trace lead of about 1 x 10(-3) M Pb(2+) was also tested.

  4. Characterization of SiC in DLC/a-Si films prepared by pulsed filtered cathodic arc using Raman spectroscopy and XPS

    International Nuclear Information System (INIS)

    Srisang, C.; Asanithi, P.; Siangchaew, K.; Pokaipisit, A.; Limsuwan, P.

    2012-01-01

    DLC/a-Si films were deposited on germanium substrates. a-Si film was initially deposited as a seed layer on the substrate using DC magnetron sputtering. DLC film was then deposited on the a-Si layer via a pulsed filtered cathodic arc (PFCA) system. In situ ellipsometry was used to monitor the thicknesses of the growth films, allowing a precise control over the a-Si and DLC thicknesses of 6 and 9 nm, respectively. It was found that carbon atoms implanting on a-Si layer act not only as a carbon source for DLC formation, but also as a source for SiC formation. The Raman peak positions at 796 cm -1 and 972 cm -1 corresponded to the LO and TO phonon modes of SiC, respectively, were observed. The results were also confirmed using TEM, XPS binding energy and XPS depth profile analysis.

  5. Sliding Wear Behaviour and Corosion Resistance to Ringer’s Solution of Uncoated and DLC Coated X46Cr13 Steel

    Directory of Open Access Journals (Sweden)

    Scendo M.

    2016-12-01

    Full Text Available Sliding wear properties and corrosion resistance in Ringer’s solution of uncoated and diamond-like carbon (DLC coated X46Cr13 steel was tested. The Raman spectra showed that the DLC film was successfully coated by plasma assisted CVD method onto the steel surface. The wear test, carried out using a ball-on disk tribometer, revealed that the DLC coating show better resistance to sliding wear and lower friction coefficient against a 100Cr6 steel ball than five times softer X46Cr13 steel. The oxidation kinetic parameters were determined by means of both the gravimetric and electrochemical method. It was found that the DLC coating markedly decreased the rate of corrosion of the X46Cr13 steel, irrespective of the corrosion mechanism involved.

  6. Description of the DLC-99/HUGO package of photon interaction data in ENDF/B-V format

    International Nuclear Information System (INIS)

    Roussin, R.W.; Knight, J.R.; Hubbell, J.H.; Howerton, R.J.

    1983-12-01

    A new photon interaction data library, DLC,-99/HUGO, is described. The library was prepared by incorporating newly evaluated data from the National Bureau of Standards with that from an existing data library, DLC-7F/HPICE, which is the ENDF/B-IV photon interaction data. It contains pair and triplet cross sections, photoelectric cross sections, and atomic form factors and the corresponding coherent scattering cross sections. Evaluated data in INDF/B-V format are provided for elements Z=1 to 100. The data package, available from the Radiation Shielding Information Center (RSIC) at Oak Ridge National Laboratory, will be submitted to CSEWG for consideration as the ENDF/B-V Photon Interaction Library. Two computer codes, EDPHOT for selectively printing the data and COMP23 for comparing two photon interaction libraries, are also provided

  7. Effect of titanium incorporation on the structural, mechanical and biocompatible properties of DLC thin films prepared by reactive-biased target ion beam deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Bharathy, P. Vijai [Thin Films and Nanomaterials Lab, School of Physical Sciences, Bharathiar University, Coimbatore 641046 (India); Department of Mechanical Engineering, University of Saskatchewan, Saskatoon (Canada); Nataraj, D., E-mail: de.natraj@gmail.com [Thin Films and Nanomaterials Lab, School of Physical Sciences, Bharathiar University, Coimbatore 641046 (India); Chu, Paul K.; Wang, Huaiyu [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Yang, Q. [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon (Canada); Kiran, M.S.R.N. [School of Physics, University of Hyderabad, Hyderabad, Andra Pradesh (India); Silvestre-Albero, J. [Laboratorio de Materiales Avanzados, Departmento de Quimica Inorganica, Universidad de Alicante, Ap 99, E-03080 Alicante (Spain); Mangalaraj, D. [Thin Films and Nanomaterials Lab, School of Physical Sciences, Bharathiar University, Coimbatore 641046 (India)

    2010-10-15

    Amorphous diamond like carbon (DLC) and titanium incorporated diamond like carbon (Ti-DLC) thin films were deposited by using reactive-biased target ion beam deposition method. The effects of Ti incorporation and target bias voltage on the microstructure and mechanical properties of the as-deposited films were investigated by means of X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy and nano-indentation. It was found that the Ti content in Ti-DLC films gets increased with increasing target bias voltage. At about 4.2 at.% of Ti, uniform sized well dispersed nanocrystals were seen in the DLC matrix. Using FFT analysis, a facility available in the TEM, it was found that the nanocrystals are in cubic TiC phase. Though at the core, the incorporated Ti atoms react with carbon to form cubic TiC; most of the surface exposed Ti atoms were found to react with the atmospheric oxygen to form weakly bonded Ti-O. The presence of TiC nanocrystals greatly modified the sp{sup 3}/sp{sup 2} hybridized bonding ratio and is reflected in mechanical hardness of Ti-DLC films. These films were then tested for their biocompatibility by an invitro cell culturing test. Morphological observation and the cell proliferation test have demonstrated that the human osteoblast cells well attach and proliferate on the surface of Ti incorporated DLC films, suggesting possible applications in bone related implant coatings.

  8. Effect of titanium incorporation on the structural, mechanical and biocompatible properties of DLC thin films prepared by reactive-biased target ion beam deposition method

    International Nuclear Information System (INIS)

    Bharathy, P. Vijai; Nataraj, D.; Chu, Paul K.; Wang, Huaiyu; Yang, Q.; Kiran, M.S.R.N.; Silvestre-Albero, J.; Mangalaraj, D.

    2010-01-01

    Amorphous diamond like carbon (DLC) and titanium incorporated diamond like carbon (Ti-DLC) thin films were deposited by using reactive-biased target ion beam deposition method. The effects of Ti incorporation and target bias voltage on the microstructure and mechanical properties of the as-deposited films were investigated by means of X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy and nano-indentation. It was found that the Ti content in Ti-DLC films gets increased with increasing target bias voltage. At about 4.2 at.% of Ti, uniform sized well dispersed nanocrystals were seen in the DLC matrix. Using FFT analysis, a facility available in the TEM, it was found that the nanocrystals are in cubic TiC phase. Though at the core, the incorporated Ti atoms react with carbon to form cubic TiC; most of the surface exposed Ti atoms were found to react with the atmospheric oxygen to form weakly bonded Ti-O. The presence of TiC nanocrystals greatly modified the sp 3 /sp 2 hybridized bonding ratio and is reflected in mechanical hardness of Ti-DLC films. These films were then tested for their biocompatibility by an invitro cell culturing test. Morphological observation and the cell proliferation test have demonstrated that the human osteoblast cells well attach and proliferate on the surface of Ti incorporated DLC films, suggesting possible applications in bone related implant coatings.

  9. Electrochemical Evaluation of Si-Incorporated Diamond-Like Carbon (DLC) Coatings Deposited on STS 316L and Ti Alloy for Biomedical Applications

    International Nuclear Information System (INIS)

    Kim, Jung Gu; Lee, Kwang Ryeol; Kim, Young Sik; Hwang, Woon Suk

    2007-01-01

    DLC coatings have been deposited onto substrate of STS 316L and Ti alloy using r.f. PACVD (plasma-assisted chemical vapor deposition) with a mixture of C 6 H 6 and SiH 4 as the process gases. Corrosion performance of DLC coatings was investigated by electrochemical techniques (potentiodynamic polarization test and electrochemical impedance spectroscopy) and surface analysis (scanning electron microscopy). the electrolyte used in this test was a 0.89% NaCl solution of pH 7.4 at temperature 37 .deg. C. The porosity and protective efficiency of DLC coatings were obtained using potentiodynamic polarization test. Moreover, the delamination area and volume fraction of water uptake of DLC coatings ass a function of immersion time were calculated using electrochemical impedance spectroscopy. This study provides the reliable and quantitative data for assessment of the effect of substrate on corrosion performance of Si-DLC coatings. the results showed that Si-DLC coating on Ti alloy could improve corrosion resistance more than that on STS 316L in the simulated body fluid environment. This could be attributed to the formation of a dense and low-porosity coating, which impedes the penetration of water and ions

  10. Surface composition variation and high-vacuum performance of DLC/ILs solid-liquid lubricating coatings: Influence of space irradiation

    International Nuclear Information System (INIS)

    Liu Xiufang; Wang Liping; Pu Jibin; Xue Qunji

    2012-01-01

    In this paper, we fabricated a DLC/ionic liquid (DLC/ILs) solid-liquid lubricating coating and investigated the effect of atomic oxygen (AO), ultraviolet (UV), proton and electron irradiations on composition, structure, morphology and tribological properties of the DLC/ILs solid-liquid lubricating coatings. A ground-based simulation facility was employed to carry out the irradiation experiments. X-ray photoelectron spectroscope (XPS), Raman spectra, and Fourier Transform Infrared Spectroscopy (FTIR) were used to analyzed the structure and composition changes of DLC film and IL lubricant before and after irradiations. The tribological behavior of the DLC/ILs solid-liquid lubricating coating before and after irradiations was investigated by a vacuum tribometer with the pressure of 10 -5 Pa. The experimental results revealed that irradiations induced the structural changes, including oxidation, bond break and crosslinking reactions of DLC film and IL lubricant. The damage of proton and AO irradiations to lubricating materials were the most serious, and UV irradiation was the slightest. After irradiations, the friction coefficient of the solid-liquid lubricating coatings decreased (except for AO irradiation), but the disc wear rate increased compared with non-irradiation coatings.

  11. High temperature tribological behaviour of carbon based (B{sub 4}C and DLC) coatings in sliding contact with aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Gharam, A. Abou, E-mail: abougha@uwindsor.c [Mechanical Automotive and Materials Engineering Department, University of Windsor, Windsor, ON, N9B3P4 (Canada); Lukitsch, M.J.; Balogh, M.P. [Chemical Sciences and Materials Systems Laboratory, General Motors R and D Center, 30500 Mound Road, Warren, MI 48090-9055 (United States); Alpas, A.T. [Mechanical Automotive and Materials Engineering Department, University of Windsor, Windsor, ON, N9B3P4 (Canada)

    2010-12-30

    Carbon based coatings, particularly diamond-like carbon (DLC) films are known to resist aluminum adhesion and reduce friction at room temperature. This attractive tribological behaviour is useful for applications such as tool coatings used for aluminum forming and machining. However, for those operations that are performed at elevated temperatures (e.g. hot forming) or that generate frictional heat during contact (e.g. dry machining) the suitable coatings are required to maintain their tribological properties at high temperatures. Candidates for these demanding applications include boron carbide (B{sub 4}C) and DLC coatings. An understanding of the mechanisms of friction, wear and adhesion of carbon based coatings against aluminum alloys at high temperatures will help in designing coatings with improved high temperature tribological properties. With this goal in mind, this study focused on B{sub 4}C and a hydrogenated DLC coatings sliding against a 319 grade cast aluminum alloy by performing pin-on-disk experiments at temperatures up to 400 {sup o}C. Experimental results have shown that the 319 Al/B{sub 4}C tribosystem generated coefficient of friction (COF) values ranging between 0.42 and 0.65, in this temperature range. However, increased amounts of aluminum adhesion were detected in the B{sub 4}C wear tracks at elevated temperatures. Focused ion beam (FIB) milled cross sections of the wear tracks revealed that the coating failed due to shearing along the columnar grain boundaries of the coating. The 319 Al/DLC tribosystem maintained a low COF (0.15-0.06) from room temperature up to 200 {sup o}C. This was followed by an abrupt increase to 0.6 at 400 {sup o}C. The deterioration of friction behaviour at T > 200 {sup o}C was attributed to the exhaustion of hydrogen and hydroxyl passivants on the carbon transfer layer formed on the Al pin.

  12. Effect of structure and deposition technology on tribological properties of DLC coatings alloyed with VIA group metals

    Science.gov (United States)

    Khrushchov, M.; Levin, I.; Marchenko, E.; Avdyukhina, V.; Petrzhik, M.

    2016-07-01

    The results of a comprehensive research on atomic structure, phase composition, micromechanical and tribological characteristics of alloyed DLC coatings have been presented. The coatings have been deposited by reactive magnetron sputtering in acetylene-nitrogen gas mixtures of different compositions (a-C:H:Cr), by plasma-assisted chemical vapor deposition in atmospheres of silicone-organic precursor gases (a-C:H:Mo:Si), and by nonreactive magnetron sputtering of a composite target (a-C:H:W).

  13. Airplane dopes and doping

    Science.gov (United States)

    Smith, W H

    1919-01-01

    Cellulose acetate and cellulose nitrate are the important constituents of airplane dopes in use at the present time, but planes were treated with other materials in the experimental stages of flying. The above compounds belong to the class of colloids and are of value because they produce a shrinking action on the fabric when drying out of solution, rendering it drum tight. Other colloids possessing the same property have been proposed and tried. In the first stages of the development of dope, however, shrinkage was not considered. The fabric was treated merely to render it waterproof. The first airplanes constructed were covered with cotton fabric stretched as tightly as possible over the winds, fuselage, etc., and flying was possible only in fine weather. The necessity of an airplane which would fly under all weather conditions at once became apparent. Then followed experiments with rubberized fabrics, fabrics treated with glue rendered insoluble by formaldehyde or bichromate, fabrics treated with drying and nondrying oils, shellac, casein, etc. It was found that fabrics treated as above lost their tension in damp weather, and the oil from the motor penetrated the proofing material and weakened the fabric. For the most part the film of material lacked durability. Cellulose nitrate lacquers, however were found to be more satisfactory under varying weather conditions, added less weight to the planes, and were easily applied. On the other hand, they were highly inflammable, and oil from the motor penetrated the film of cellulose nitrate, causing the tension of the fabric to be relaxed.

  14. Rehealable, fully recyclable, and malleable electronic skin enabled by dynamic covalent thermoset nanocomposite.

    Science.gov (United States)

    Zou, Zhanan; Zhu, Chengpu; Li, Yan; Lei, Xingfeng; Zhang, Wei; Xiao, Jianliang

    2018-02-01

    Electronic skin (e-skin) mimicking functionalities and mechanical properties of natural skin can find broad applications. We report the first dynamic covalent thermoset-based e-skin, which is connected through robust covalent bonds, rendering the resulting devices good chemical and thermal stability at service condition. By doping the dynamic covalent thermoset with conductive silver nanoparticles, we demonstrate a robust yet rehealable, fully recyclable, and malleable e-skin. Tactile, temperature, flow, and humidity sensing capabilities are realized. The e-skin can be rehealed when it is damaged and can be fully recycled at room temperature, which has rarely, if at all, been demonstrated for e-skin. After rehealing or recycling, the e-skin regains mechanical and electrical properties comparable to the original e-skin. In addition, malleability enables the e-skin to permanently conform to complex, curved surfaces without introducing excessive interfacial stresses. These properties of the e-skin yield an economical and eco-friendly technology that can find broad applications in robotics, prosthetics, health care, and human-computer interface.

  15. Solution structure of tensin2 SH2 domain and its phosphotyrosine-independent interaction with DLC-1.

    Directory of Open Access Journals (Sweden)

    Kun Dai

    Full Text Available Src homology 2 (SH2 domain is a conserved module involved in various biological processes. Tensin family member was reported to be involved in tumor suppression by interacting with DLC-1 (deleted-in-liver-cancer-1 via its SH2 domain. We explore here the important questions that what the structure of tensin2 SH2 domain is, and how it binds to DLC-1, which might reveal a novel binding mode.Tensin2 SH2 domain adopts a conserved SH2 fold that mainly consists of five β-strands flanked by two α-helices. Most SH2 domains recognize phosphorylated ligands specifically. However, tensin2 SH2 domain was identified to interact with nonphosphorylated ligand (DLC-1 as well as phosphorylated ligand.We determined the solution structure of tensin2 SH2 domain using NMR spectroscopy, and revealed the interactions between tensin2 SH2 domain and its ligands in a phosphotyrosine-independent manner.

  16. Micro-texturing into DLC/diamond coated molds and dies via high density oxygen plasma etching

    Directory of Open Access Journals (Sweden)

    Yunata Ersyzario Edo

    2015-01-01

    Full Text Available Diamond-Like Carbon (DLC and Chemical Vapor Deposition (CVD-diamond films have been widely utilized not only as a hard protective coating for molds and dies but also as a functional substrate for bio-MEMS/NEMS. Micro-texturing into these hard coated molds and dies provides a productive tool to duplicate the original mother micro-patterns onto various work materials and to construct any tailored micro-textures for sensors and actuators. In the present paper, the high density oxygen plasma etching method is utilized to make micro-line and micro-groove patterns onto the DLC and diamond coatings. Our developing oxygen plasma etching system is introduced together with characterization on the plasma state during etching. In this quantitative plasma diagnosis, both the population of activated species and the electron and ion densities are identified through the emissive light spectroscopy and the Langmuir probe method. In addition, the on-line monitoring of the plasmas helps to describe the etching process. DLC coated WC (Co specimen is first employed to describe the etching mechanism by the present method. Chemical Vapor Deposition (CVD diamond coated WC (Co is also employed to demonstrate the reliable capacity of the present high density oxygen plasma etching. This oxygen plasma etching performance is discussed by comparison of the etching rates.

  17. Genesis and stability of tribolayers in solid lubrication: case of pair DLC-stainless steel

    Directory of Open Access Journals (Sweden)

    Diego Berti Salvaro

    2016-04-01

    Full Text Available The morphology, dimensions and chemical composition of tribolayers strongly depend on the pressures and temperatures acting on the contact. They are formed by reactions between surfaces in contact with each other as well as with the atmosphere, lubricants and possible contaminants. In this paper, the influence of test time (180, 500, 1000 and 2500 h on the formation and characteristics of tribolayers in pairs of DLC-stainless steel that were tested under an atmosphere of refrigerant gas R134a and without lubricating oil was analyzed. The characterization was performed using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS (morphology and chemical composition and white light interferometry (thickness. The tribolayer thicknesses ranged from 100 to 500 nm, and they were composed of elements originating from mutual transfers between the tribological pairs, as well as oxides that were more pronounced on the stainless steel surface. The results show that the tribolayers are chemically stable, maintaining the same composition over time, and their thicknesses remained constant after 1000 h of testing.

  18. Characteristics of CrAlSiN + DLC coating deposited by lateral rotating cathode arc PVD and PACVD process

    Energy Technology Data Exchange (ETDEWEB)

    Lukaszkowicz, Krzysztof, E-mail: krzysztof.lukaszkowicz@polsl.pl [Institute of Engineering Materials and Biomaterials, Silesian University of Technology, Konarskiego St. 18A, 44-100 Gliwice (Poland); Sondor, Jozef, E-mail: j.sondor@liss.cz [LISS, a.s., Dopravni 2603, 756 61 Roznov p.R. (Czech Republic); Balin, Katarzyna, E-mail: katarzyna.balin@us.edu.pl [A. Chełkowski Institute of Physic, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Kubacki, Jerzy, E-mail: jerzy.kubacki@us.edu.pl [A. Chełkowski Institute of Physic, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland)

    2014-09-01

    Highlights: • The chemical composition of the CrAlSiN + DLC coatings was studied. • The coatings have nanostructural character with fine crystallites. • Their average size grain is less than 10 nm. • The coatings demonstrate friction coefficient within the range 0.05–0.07. • The coating demonstrated a dense cross-sectional morphology as well as good adhesion to the substrate. - Abstract: Coating system composed of CrAlSiN film covered by diamond-like carbon (DLC)-based lubricant, deposited on hot work tool steel substrate was the subject of the research. The CrAlSiN and DLC layers were deposited by PVD lateral rotating ARC-cathodes (LARC) and PACVD technology on the X40CrMoV5-1 respectively. HRTEM investigation shows an amorphous character of DLC layer. It was found that the tested CrAlSiN layer has a nanostructural character with fine crystallites while their average size is less than 10 nm. Based on the XRD pattern of the CrAlSiN, the occurrence of fcc phase was only observed in the coating, the texture direction 〈3 1 1〉 is perpendicular to the sample surface. Combined SEM, AES and ToF-SIMS studies confirmed assumed chemical composition and layered structure of the coating. The chemical distribution of the elements inside the layers and at the interfaces was analyzed by SEM and AES methods. It was shown that additional CrN layer is present between substrate and CrAlSiN coating. The atomic concentration of the particular elements of DLC and CrAlSiN layer was calculated from the XPS measurements. In sliding dry friction conditions the friction coefficient for the investigated elements is set in the range between 0.05 and 0.07. The investigated coating reveals high wear resistance. The coating demonstrated a dense cross-sectional morphology as well as good adhesion to the substrate.

  19. Covalent modification of platelet proteins by palmitate

    International Nuclear Information System (INIS)

    Muszbek, L.; Laposata, M.

    1989-01-01

    Covalent attachment of fatty acid to proteins plays an important role in association of certain proteins with hydrophobic membrane structures. In platelets, the structure of many membrane glycoproteins (GPs) has been examined in detail, but the question of fatty acid acylation of platelet proteins has not been addressed. In this study, we wished to determine (a) whether platelet proteins could be fatty acid acylated; and, if so, (b) whether these modified proteins were present in isolated platelet membranes and cytoskeletal fractions; and (c) if the pattern of fatty acid acylated proteins changed on stimulation of the platelets with the agonist thrombin. We observed that in platelets allowed to incorporate 3H-palmitate, a small percentage (1.37%) of radioactivity incorporated into the cells became covalently bound to protein. Selective cleavage of thioester, thioester plus O-ester, and amide-linked 3H-fatty acids from proteins, and their subsequent analysis by high-performance liquid chromatography (HPLC) indicated that the greatest part of 3H-fatty acid covalently bound to protein was thioester-linked 3H-palmitate. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and fluorography, at least ten major radiolabeled proteins were detected. Activation of platelets by thrombin greatly increased the quantity of 3H-palmitoylated proteins associated with the cytoskeleton. Nearly all radiolabeled proteins were recovered in the membrane fraction, indicating that these proteins are either integral or peripheral membrane proteins or proteins tightly associated to membrane constituents. Components of the GPIIb-IIIa complex were not palmitoylated. Thus, platelet proteins are significantly modified posttranslationally by 3H-palmitate, and incorporation of palmitoylated proteins into the cytoskeleton is a prominent component of the platelet response to thrombin stimulation

  20. Design of a covalently bonded glycosphingolipid microarray

    DEFF Research Database (Denmark)

    Arigi, Emma; Blixt, Klas Ola; Buschard, Karsten

    2012-01-01

    , the major classes of plant and fungal GSLs. In this work, a prototype "universal" GSL-based covalent microarray has been designed, and preliminary evaluation of its potential utility in assaying protein-GSL binding interactions investigated. An essential step in development involved the enzymatic release...... of the fatty acyl moiety of the ceramide aglycone of selected mammalian GSLs with sphingolipid N-deacylase (SCDase). Derivatization of the free amino group of a typical lyso-GSL, lyso-G(M1), with a prototype linker assembled from succinimidyl-[(N-maleimidopropionamido)-diethyleneglycol] ester and 2...

  1. Synthesis and characterization of CrCN–DLC composite coatings by cathodic arc ion-plating

    Energy Technology Data Exchange (ETDEWEB)

    Wang, R.Y. [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); Wang, L.L. [Key Laboratory of Artificial Nanomaterials and Nanostructure of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Liu, H.D. [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); Yan, S.J. [Key Laboratory of Artificial Nanomaterials and Nanostructure of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Chen, Y.M. [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); Fu, D.J. [Key Laboratory of Artificial Nanomaterials and Nanostructure of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Yang, B., E-mail: toyangbing@163.com [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China)

    2013-07-15

    CrCN–DLC composite coatings were deposited onto silicon (1 0 0) and cemented carbides substrates using pure Cr targets under C{sub 2}H{sub 2} ambient by cathodic arc ion plating system. The influence of C{sub 2}H{sub 2} flow rate on the structure and mechanical properties of the coatings was investigated systemically. The coatings structure and bonding state were characterized by XRD, Raman and X-ray photoelectron spectroscopy. The chemical composition was measured by EDS. The mechanical performance and tribological behaviour of the coatings were studied by a hardness tester and ball-on-disc wear tester. The results showed that with increasing C{sub 2}H{sub 2} flow rate from 50 to 100 sccm, the corresponding hardness of coatings increased firstly and then decreased with further addition of C{sub 2}H{sub 2} flow rate. The coatings deposited at lower C{sub 2}H{sub 2} flow rate (less than 200 sccm) exhibited a relatively higher hardness value (more than HV{sub 0.025}2000) and then the hardness decrease with increasing C{sub 2}H{sub 2} flow rate. The friction coefficient also exhibited similar variation trend, when the C{sub 2}H{sub 2} flow rate was higher than 100 sccm, the friction coefficient decreased and then maintained in a relatively lower value from 0.18 to 0.24, which may be attribute to the increasing carbon content and the coating exhibited more diamond-like structure.

  2. Tribological study of novel metal-doped carbon-based coatings with enhanced thermal stability

    Science.gov (United States)

    Mandal, Paranjayee

    and M0S2. This mechanism is believed to be the key-factor for low friction properties of Mo-W-C coating and presence of graphitic carbon particles further benefits the friction behaviour. It is observed that low friction is achieved mostly due to formation of WS2 at ambient temperature, whereas formation of both WS2 and M0S2 significantly decreases the friction of Mo-W-C coating at high temperature. This further indicates importance of combined Mo and W doping over single-metal doping into carbon-based coatings.Isothermal oxidation tests indicate that Mo-W-C coating preserves it's as-deposited graphitic nature up to 500°C, whereas local delamination of DLC coating leads to substrate exposure and loss of its diamond-like structure at the same temperature. Further, thermo-gravimetric tests confirm excellent thermal stability of Mo-W-C coating compared to DLC. Mo-W-C coating resists oxidation up to 800°C and no coating delamination is observed due to retained coating integrity and its strong adhesion with substrate. On the other hand, state-of-the-art DLC coating starts to delaminate beyond 380°C.The test results confirm that Mo-W-C coating sustains high working temperature and simultaneously maintains improved tribological properties during boundary lubricated condition at ambient and high temperature. Thus Mo-W-C coating is a suitable candidate for low friction and high temperature wear resistant applications compared to commercially available state-of-the-art DLC coatings.

  3. New solutions for effective access powerline solutions. The European smart grid project DLC+VIT4IP; Neue Ansaetz fuer leistungsfaehige Access-Powerline-Loesungen. Das Europaeische Smart-Grid Projekt DLC+VIT4IP

    Energy Technology Data Exchange (ETDEWEB)

    Offner, Georg [devolo AG, Aachen (Germany)

    2011-07-01

    By the European DLC+VIT4IP project the development of innovative smart grid solutions for a better handling of energy resources is forced. Smart grid ensures the stable operation of a decentralized electric supply network, where more and more small suppliers contribute by solar or wind energy technology. Business customers as well as private customers benefit from smart grid, as they get instant information about their actual consumption by the Internet. Covered by the project there will be developed new approaches of access powerline communications which provide an effective, IPv6 based communication e.g. between electric meters at home and the power net station. (orig.)

  4. Effect of aqueous solution and load on the formation of DLC transfer layer against Co-Cr-Mo for joint prosthesis.

    Science.gov (United States)

    Guo, Feifei; Zhou, Zhifeng; Hua, Meng; Dong, Guangneng

    2015-09-01

    Diamond-like carbon (DLC) coating exhibits excellent mechanical properties such as high hardness, low friction and wear, which offer a promising solution for the metal-on-metal hip joint implants. In the study, the hydrogen-free DLC coating with the element Cr as the interlay addition was deposited on the surface of the Co-Cr-Mo alloy by a unbalanced magnetron sputtering method. The coating thickness was controlled as 2 µm. Nano-indentation test indicated the hardness was about 13 GPa. DLC coated Co-Cr-Mo alloy disc against un-coated Co-Cr-Mo alloy pin (spherical end SR9.5) comprised the friction pairs in the pin-on-disc tribotest under bovine serum albumin solution (BSA) and physiological saline(PS).The tribological behavior under different BSA concetrations(2-20 mg/ml), and applied load (2-15N) was investigated.DLC transfer layer did not form under BSA solution, even though different BSA concetration and applied load changed. The coefficient of friction(COF) under 6 mg/ml BSA at 10 N was the lowest as 0.10. A higher COF of 0.13 was obtained under 20 mg/ml BSA. The boundary absorption layer of protein is the main factor for the counterparts. However, the continous DLC transfer layer was observed under PS solution, which make a lower COF of 0.08. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Blood compatibility of gas plasma-treated diamond-like carbon surface-Effect of physicochemical properties of DLC surface on blood compatibility

    International Nuclear Information System (INIS)

    Mochizuki, Akira; Ogawa, Tatsuhisa; Okamoto, Keishi; Nakatani, Tatsuyuki; Nitta, Yuki

    2011-01-01

    From the knowledge that zwitterion-type polymers show good blood compatibility, the introduction of both cationic and anionic functional groups onto diamond-like carbon (DLC) surface is expected to improve blood compatibility. Thus, DLC films were treated with oxygen and ammonia gas plasmas. The surfaces were characterized in terms of chemical composition by XPS, contact angle, and zeta potential. XPS analysis showed the introductions of a carboxyl group by oxygen plasma treatment and nitrogen atoms by ammonia plasma treatment. The evaluation of blood compatibility for the DLC surfaces was carried out in terms of platelets and the coagulation system. Excellent improvement of platelet compatibility was observed by the treatment with the gas plasmas, regardless of the plasma species. As for the compatibility with the coagulation system, DLC surfaces with a high concentration of carboxyl groups (COOH) markedly activated the system via the intrinsic pathway. However, the surfaces treated with ammonia plasma did not activate the system even though they had high COOH concentration. Measurement of the zeta potential revealed that the ammonia plasma treatment raised the potential from a negative value to a positive one. Though the introduction of amino groups to the surface was not detected directly, the treatment of ammonia plasma changed the electrical state of the DLC surface having COOH group, causing a difference in blood compatibility among the DLCs obtained by various plasma conditions.

  6. Revisiting nitrogen species in covalent triazine frameworks

    KAUST Repository

    Osadchii, Dmitrii Yu.

    2017-11-28

    Covalent triazine frameworks (CTFs) are porous organic materials promising for applications in catalysis and separation due to their high stability, adjustable porosity and intrinsic nitrogen functionalities. CTFs are prepared by ionothermal trimerization of aromatic nitriles, however, multiple side reactions also occur under synthesis conditions, and their influence on the material properties is still poorly described. Here we report the systematic characterization of nitrogen in CTFs using X-ray photoelectron spectroscopy (XPS). With the use of model compounds, we could distinguish several types of nitrogen species. By combining these data with textural properties, we unravel the influence that the reaction temperature, the catalyst and the monomer structure and composition have on the properties of the resulting CTF materials.

  7. Non-covalent associative structure of coal

    Energy Technology Data Exchange (ETDEWEB)

    Shui, H. [Anhui University of Technology, Maanshan (China). School of Chemistry and Chemical Engineering

    2004-06-01

    The recent progress of non-covalent associative structure of coal and the mechanisms of the carbon disulphide-N-methyl-2-pyrrolidone (CS{sub 2}/NMP) are mixed solvent and the additive addition enhancing the extraction yield of coals are reviewed, and the aggregation behaviour of coal in solid and solution states are presented, and the aggregation behavior of coal in solid and solution states are introduced in this paper. Coal extraction and swelling in organic solvents at room temperature were the most useful methods to understand the associative structure of coal. CS{sub 2}/NMP is a unique solvent to give high extraction yields for some bituminous coals. Some additives such as tetracyanoethylene (TCNE) can dissociate the stronger interactions among coal molecules and enhance the extraction yields of coal in the mixed solvent. 37 refs., 1 fig.

  8. Novel hydroxyapatite biomaterial covalently linked to raloxifene.

    Science.gov (United States)

    Meme, L; Santarelli, A; Marzo, G; Emanuelli, M; Nocini, P F; Bertossi, D; Putignano, A; Dioguardi, M; Lo Muzio, L; Bambini, F

    2014-01-01

    Since raloxifene, a drug used in osteoporosis therapy, inhibits osteoclast, but not osteoblast functions, it has been suggested to improve recovery during implant surgery. The present paper describes an effective method to link raloxifene, through a covalent bond, to a nano-Hydroxyapatite-based biomaterial by interfacing with (3-aminopropyl)-Triethoxysilane as assessed by Infra Red-Fourier Transformed (IR-FT) spectroscopy and Scanning Electron Microscope (SEM). To evaluate the safety of this modified new material, the vitality of osteoblast-like cells cultured with the new biomaterial was then investigated. Raloxifene-conjugated HAbiomaterial has been shown to be a safe material easy to obtain which could be an interesting starting point for the use of a new functional biomaterial suitable in bone regeneration procedures.

  9. Biofunctional Paper via Covalent Modification of Cellulose

    Science.gov (United States)

    Yu, Arthur; Shang, Jing; Cheng, Fang; Paik, Bradford A.; Kaplan, Justin M.; Andrade, Rodrigo B.; Ratner, Daniel M.

    2012-01-01

    Paper-based analytical devices are the subject of growing interest for the development of low-cost point-of-care diagnostics, environmental monitoring technologies and research tools for limited-resource settings. However, there are limited chemistries available for the conjugation of biomolecules to cellulose for use in biomedical applications. Herein, divinyl sulfone (DVS) chemistry was demonstrated to covalently immobilize small molecules, proteins and DNA onto the hydroxyl groups of cellulose membranes through nucleophilic addition. Assays on modified cellulose using protein-carbohydrate and protein-glycoprotein interactions as well as oligonucleotide hybridization showed that the membrane’s bioactivity was specific, dose-dependent, and stable over a long period of time. Use of an inkjet printer to form patterns of biomolecules on DVS-activated cellulose illustrates the adaptability of the DVS functionalization technique to pattern sophisticated designs, with potential applications in cellulose-based lateral flow devices. PMID:22708701

  10. Revisiting nitrogen species in covalent triazine frameworks

    KAUST Repository

    Osadchii, Dmitrii Yu.; Olivos Suarez, Alma Itzel; Bavykina, Anastasiya V.; Gascon, Jorge

    2017-01-01

    Covalent triazine frameworks (CTFs) are porous organic materials promising for applications in catalysis and separation due to their high stability, adjustable porosity and intrinsic nitrogen functionalities. CTFs are prepared by ionothermal trimerization of aromatic nitriles, however, multiple side reactions also occur under synthesis conditions, and their influence on the material properties is still poorly described. Here we report the systematic characterization of nitrogen in CTFs using X-ray photoelectron spectroscopy (XPS). With the use of model compounds, we could distinguish several types of nitrogen species. By combining these data with textural properties, we unravel the influence that the reaction temperature, the catalyst and the monomer structure and composition have on the properties of the resulting CTF materials.

  11. Pore surface engineering in covalent organic frameworks.

    Science.gov (United States)

    Nagai, Atsushi; Guo, Zhaoqi; Feng, Xiao; Jin, Shangbin; Chen, Xiong; Ding, Xuesong; Jiang, Donglin

    2011-11-15

    Covalent organic frameworks (COFs) are a class of important porous materials that allow atomically precise integration of building blocks to achieve pre-designable pore size and geometry; however, pore surface engineering in COFs remains challenging. Here we introduce pore surface engineering to COF chemistry, which allows the controlled functionalization of COF pore walls with organic groups. This functionalization is made possible by the use of azide-appended building blocks for the synthesis of COFs with walls to which a designable content of azide units is anchored. The azide units can then undergo a quantitative click reaction with alkynes to produce pore surfaces with desired groups and preferred densities. The diversity of click reactions performed shows that the protocol is compatible with the development of various specific surfaces in COFs. Therefore, this methodology constitutes a step in the pore surface engineering of COFs to realize pre-designed compositions, components and functions.

  12. Cell Signalling Through Covalent Modification and Allostery

    Science.gov (United States)

    Johnson, Louise N.

    Phosphorylation plays essential roles in nearly every aspect of cell life. Protein kinases catalyze the transfer of the γ-phosphate of ATP to a serine, threonine or tyrosine residue in protein substrates. This covalent modification allows activation or inhibition of enzyme activity, creates recognition sites for other proteins and promotes order/disorder or disorder/order transitions. These properties regulate ­signalling pathways and cellular processes that mediate metabolism, transcription, cell cycle progression, differentiation, cytoskeleton arrangement and cell movement, apoptosis, intercellular communication, and neuronal and immunological functions. In this lecture I shall review the structural consequences of protein phosphorylation using our work on glycogen phosphorylase and the cell cycle cyclin dependent protein kinases as illustrations. Regulation of protein phosphorylation may be disrupted in the diseased state and protein kinases have become high profile targets for drug development. To date there are 11 compounds that have been approved for clinical use in the treatment of cancer.

  13. Doping droops.

    Science.gov (United States)

    Chaturvedi, Aditi; Chaturvedi, Harish; Kalra, Juhi; Kalra, Sudhanshu

    2007-01-01

    Drug abuse is a major concern in the athletic world. The misconception among athletes and their coaches is that when an athlete breaks a record it is due to some "magic ingredient" and not because of training, hard work, mental attitude and championship performance. The personal motivation to win in competitive sports has been intensified by national, political, professional and economic incentives. Under this increased pressure athletes have turned to finding this "magic ingredient". Athlete turns to mechanical (exercise, massage), nutritional (vitamins, minerals), pharmacological (medicines) or gene therapies to have an edge over other players. The World Anti-Doping Agency (WADA) has already asked scientists to help find ways to prevent gene therapy from becoming the newest form of doping. The safety of the life of athletes is compromised with all forms of doping techniques, be it a side effect of a drug or a new technique of gene doping.

  14. Covalent versus ionic bonding in alkalimetal fluoride oligomers

    NARCIS (Netherlands)

    Bickelhaupt, F.M.; Sola, M.; Fonseca Guerra, C.

    2007-01-01

    The most polar bond in chemistry is that between a fluorine and an alkalimetal atom. Inspired by our recent finding that other polar bonds (C - M and H - M) have important covalent contributions (i.e., stabilization due to bond overlap), we herein address the question if covalency is also essential

  15. A study of the performance and properties of diamond like carbon (DLC) coatings deposited by plasma chemical vapor deposition (CVD) for two stroke engine components

    Energy Technology Data Exchange (ETDEWEB)

    Tither, D. [BEP Grinding Ltd., Manchester (United Kingdom); Ahmed, W.; Sarwar, M.; Penlington, R. [Univ. of Northumbria, Newcastle-upon-Tyne (United Kingdom)

    1995-12-31

    Chemical vapor deposition (CVD) using microwave and RF plasma is arguably the most successful technique for depositing diamond and diamond like carbon (DLC) films for various engineering applications. However, the difficulties of depositing diamond are nearly as extreme as it`s unique combination of physical, chemical and electrical properties. In this paper, the modified low temperature plasma enhanced CVD system is described. The main focus of this paper will be work related to deposition of DLC on metal matrix composite materials (MMCs) for application in two-stroke engine components and results will be presented from SEM, mechanical testing and composition analysis studies. The authors have demonstrated the feasibility of depositing DLC on MMCs for the first time using a vacuum deposition process.

  16. Chemically fixed p-n heterojunctions for polymer electronics by means of covalent B-F bond formation

    Science.gov (United States)

    Hoven, Corey V.; Wang, Huiping; Elbing, Mark; Garner, Logan; Winkelhaus, Daniel; Bazan, Guillermo C.

    2010-03-01

    Widely used solid-state devices fabricated with inorganic semiconductors, including light-emitting diodes and solar cells, derive much of their function from the p-n junction. Such junctions lead to diode characteristics and are attained when p-doped and n-doped materials come into contact with each other. Achieving bilayer p-n junctions with semiconducting polymers has been hindered by difficulties in the deposition of thin films with independent p-doped and n-doped layers. Here we report on how to achieve permanently fixed organic p-n heterojunctions by using a cationic conjugated polyelectrolyte with fluoride counteranions and an underlayer composed of a neutral conjugated polymer bearing anion-trapping functional groups. Application of a bias leads to charge injection and fluoride migration into the neutral layer, where irreversible covalent bond formation takes place. After the initial charging and doping, one obtains devices with no delay in the turn on of light-emitting electrochemical behaviour and excellent current rectification. Such devices highlight how mobile ions in organic media can open opportunities to realize device structures in ways that do not have analogies in the world of silicon and promise new opportunities for integrating organic materials within technologies now dominated by inorganic semiconductors.

  17. Study of the Thermal Decomposition of PFPEs Lubricants on a Thin DLC Film Using Finitely Extensible Nonlinear Elastic Potential Based Molecular Dynamics Simulation

    International Nuclear Information System (INIS)

    Deb Nath, S.K.; Deb Nath, S.K.; Wong, C.H.; Deb Nath, S.K.

    2014-01-01

    Perfluoro polyethers (PFPEs) are widely used as hard disk lubricants for protecting carbon overcoat reducing friction between the hard disk interface and the head during the movement of head during reading and writing data in the hard disk. Due to temperature rise of PFPE Zdol lubricant molecules on a DLC surface, how polar end groups are detached from lubricant molecules during coating is described considering the effect of temperatures on the bond/break density of PFPE Zdol using the coarse-grained bead spring model based on finitely extensible nonlinear elastic potential. As PFPE Z contains no polar end groups, effects of temperature on the bond/break density (number of broken bonds/total number of bonds) are not so significant like PFPE Zdol. Effects of temperature on the bond/break density of PFPE Z on DLC surface are also discussed with the help of graphical results. How bond/break phenomenon affects the end bead density of PFPE Z and PFPE Zdol on DLC surface is discussed elaborately. How the overall bond length of PFPE Zdol increases with the increase of temperature which is responsible for its decomposition is discussed with the help of graphical results. At HAMR condition, as PFPE Z and PFPE Zdol are not suitable lubricant on a hard disk surface, it needs more investigations to obtain suitable lubricant. We study the effect of breaking of bonds of nonfunctional lubricant PFPE Z, functional lubricants such as PFPE Zdol and PFPE Ztetrao, and multi dented functional lubricants such as Ar-DS, ARJ-DD, and OHJ-DS on a DLC substrate with the increase of temperature when heating of all of the lubricants on a DLC substrate is carried out isothermally using the coarse-grained bead spring model by molecular dynamics simulations and suitable lubricant is selected which is suitable on a DLC substrate at high temperature.

  18. Study of the Thermal Decomposition of PFPEs Lubricants on a Thin DLC Film Using Finitely Extensible Nonlinear Elastic Potential Based Molecular Dynamics Simulation

    Directory of Open Access Journals (Sweden)

    S. K. Deb Nath

    2014-01-01

    Full Text Available Perfluoropolyethers (PFPEs are widely used as hard disk lubricants for protecting carbon overcoat reducing friction between the hard disk interface and the head during the movement of head during reading and writing data in the hard disk. Due to temperature rise of PFPE Zdol lubricant molecules on a DLC surface, how polar end groups are detached from lubricant molecules during coating is described considering the effect of temperatures on the bond/break density of PFPE Zdol using the coarse-grained bead spring model based on finitely extensible nonlinear elastic potential. As PFPE Z contains no polar end groups, effects of temperature on the bond/break density (number of broken bonds/total number of bonds are not so significant like PFPE Zdol. Effects of temperature on the bond/break density of PFPE Z on DLC surface are also discussed with the help of graphical results. How bond/break phenomenonaffects the end bead density of PFPE Z and PFPE Zdol on DLC surface is discussed elaborately. How the overall bond length of PFPE Zdol increases with the increase of temperature which is responsible for its decomposition is discussed with the help of graphical results. At HAMR condition, as PFPE Z and PFPE Zdol are not suitable lubricant on a hard disk surface, it needs more investigations to obtain suitable lubricant. We study the effect of breaking of bonds of nonfunctional lubricant PFPE Z, functional lubricants such as PFPE Zdol and PFPE Ztetrao, and multidented functional lubricants such as ARJ-DS, ARJ-DD, and OHJ-DS on a DLC substrate with the increase of temperature when heating of all of the lubricants on a DLC substrate is carried out isothermally using the coarse-grained bead spring model by molecular dynamics simulations and suitable lubricant is selected which is suitable on a DLC substrate at high temperature.

  19. Nd:YOV4 laser surface texturing on DLC coating: Effect on morphology, adhesion, and dry wear behavior

    Science.gov (United States)

    Surfaro, Maria; Giorleo, Luca; Montesano, Lorenzo; Allegri, Gabriele; Ceretti, Elisabetta; La Vecchia, Giovina Marina

    2018-05-01

    The surface of structural components is usually subjected to higher stresses, greater wear or fatigue damage, and more direct environmental exposure than the inner parts. For this reason, the interest to improve superficial properties of items is constantly increasing in different fields as automotive, electronic, biomedical, etc. Different approaches can be used to achieve this goal: case hardening by means of superficial heat treatments like carburizing or nitriding, deposition of thin or thick coatings, roughness modification, etc. Between the available technologies to modify components surface, Laser Surface Texturing (LST) has already been recognized in the last decade as a process, which improves the tribological properties of various parts. Based on these considerations the aim of the present research work was to realize a controlled laser texture on a Diamond-like Carbon (DLC) thin coating (about 3 µm thick) without damaging both the coating itself and the substrate. In particular, the effect of laser process parameters as marking speed and loop cycle were investigated in terms of texture features modifications. Both qualitative and quantitative analyses of the texture were executed by using a scanning electron microscope and a laser probe system to select the proper laser parameters. Moreover, the effect of the selected texture on the DLC nanohardness, adhesion and wear behavior was pointed out.

  20. Surface characterization and biological evaluation of silver-incorporated DLC coatings fabricated by hybrid RF PACVD/MS method.

    Science.gov (United States)

    Bociąga, Dorota; Jakubowski, Witold; Komorowski, Piotr; Sobczyk-Guzenda, Anna; Jędrzejczak, Anna; Batory, Damian; Olejnik, Anna

    2016-06-01

    Since the biological response of the body towards an implanted material is mainly governed by its surface properties, biomaterials are improved by various kinds of coatings. Their role is to provide good mechanical and biological characteristics, and exclude some disadvantages like post-implantation infections. This phenomenon may be reduced by introduction of silver as an antibacterial agent. This study evaluates the Ag-DLC films synthesized by the hybrid RF PACVD/MS method according to the patent number PL401955-A1 worked out inter alia by the authors. Such tests as XPS, SEM, EDS, AFM, FTIR, Raman and ICP-TOF-MS were used to determine surface properties of the coatings. The obtained results were correlated with the biological response estimated on the basis of cells viability assay (osteoblast cells line Saos-2) and bacterial colonization test (Escherichia coli strain DH5α). Results showed that the hybrid RF PACVD/MS method allows one to get tight coating preventing the diffusion of harmful elements from the metallic substrate. Ag concentration increases with the growing power density, it occurs in metallic state, does not create chemical bonds and is evenly dispersed within the DLC matrix in the form of nanoscale silver clusters. Increasing silver content above 2at.% improves bactericidal properties, but decreases cell viability. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Laser Raman microprobe spectroscopy as a diagnostic for the characterisation of diamond and diamond like carbon (DLC) thin films

    International Nuclear Information System (INIS)

    Johnston, C.

    1990-10-01

    Invariably when manufacturing an artificial diamond film a mixture of carbon is deposited - tetragonally bonded (diamond), trigonally bonded (graphite) and other allotropic crystalline forms and amorphous carbons. This imposes a need for careful analysis to determine exactly what carbon types constitute the films. Raman spectroscopy is particularly sensitive to crystal and atomic structure and has a number of advantages which make it one of the most useful techniques for interrogating diamond and DLC thin films. Although Raman spectroscopy alone cannot fully characterise the film, it can give more information than simply what particular form of carbon or other impurities are present in the film. It can be used to determine the ratio of sp 2 to sp 3 bonding within the film, and to some extent the crystallite or domain size and the internal stress of the film. The use of laser Raman microprobe spectroscopy as a diagnostic tool in the analysis of diamond and DLC thin films is demonstrated for a variety of carbon films on various substrates and the characterisation of these films is discussed. (author)

  2. Investigation of structure, adhesion strength, wear performance and corrosion behavior of platinum/ruthenium/nitrogen doped diamond-like carbon thin films with respect to film thickness

    Energy Technology Data Exchange (ETDEWEB)

    Khun, N.W. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Liu, E., E-mail: MEJLiu@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2011-03-15

    Research highlights: {yields} Sputtered PtRuN-DLC thin films were fabricated with different film thicknesses. {yields} The graphitization of the films increased with increased film thickness. {yields} The wear resistance of the films increased though their adhesion strength decreased. {yields} The corrosion potentials of the films shifted to more negative values. {yields} However, the corrosion currents of the films decreased. - Abstract: In this study, the corrosion performance of platinum/ruthenium/nitrogen doped diamond-like carbon (PtRuN-DLC) thin films deposited on p-Si substrates using a DC magnetron sputtering deposition system in a 0.1 M NaCl solution was investigated using potentiodynamic polarization test in terms of film thickness. The effect of the film thickness on the chemical composition, bonding structure, surface morphology, adhesion strength and wear resistance of the PtRuN-DLC films was studied using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM), micro-scratch test and ball-on-disc tribotest, respectively. It was found that the wear resistance of the PtRuN-DLC films apparently increased with increased film thickness though the adhesion strength of the films decreased. The corrosion results revealed that the increased concentration of sp{sup 2} bonds in the PtRuN-DLC films with increased film thickness shifted the corrosion potentials of the films to more negative values but the decreased porosity density in the films significantly decreased the corrosion currents of the films.

  3. Covalent functionalization and passivation of exfoliated black phosphorus via aryl diazonium chemistry

    Science.gov (United States)

    Ryder, Christopher R.; Wood, Joshua D.; Wells, Spencer A.; Yang, Yang; Jariwala, Deep; Marks, Tobin J.; Schatz, George C.; Hersam, Mark C.

    2016-06-01

    Functionalization of atomically thin nanomaterials enables the tailoring of their chemical, optical and electronic properties. Exfoliated black phosphorus (BP)—a layered two-dimensional semiconductor—exhibits favourable charge-carrier mobility, tunable bandgap and highly anisotropic properties, but it is chemically reactive and degrades rapidly in ambient conditions. Here we show that covalent aryl diazonium functionalization suppresses the chemical degradation of exfoliated BP even after three weeks of ambient exposure. This chemical modification scheme spontaneously forms phosphorus-carbon bonds, has a reaction rate sensitive to the aryl diazonium substituent and alters the electronic properties of exfoliated BP, ultimately yielding a strong, tunable p-type doping that simultaneously improves the field-effect transistor mobility and on/off current ratio. This chemical functionalization pathway controllably modifies the properties of exfoliated BP, and thus improves its prospects for nanoelectronic applications.

  4. The protein inhibitor of nNOS (PIN/DLC1/LC8) binding does not inhibit the NADPH-dependent heme reduction in nNOS, a key step in NO synthesis

    International Nuclear Information System (INIS)

    Parhad, Swapnil S.; Jaiswal, Deepa; Ray, Krishanu; Mazumdar, Shyamalava

    2016-01-01

    The neuronal nitric oxide synthase (nNOS) is an essential enzyme involved in the synthesis of nitric oxide (NO), a potent neurotransmitter. Although previous studies have indicated that the dynein light chain 1 (DLC1) binding to nNOS could inhibit the NO synthesis, the claim is challenged by contradicting reports. Thus, the mechanism of nNOS regulation remained unclear. nNOS has a heme-bearing, Cytochrome P450 core, and the functional enzyme is a dimer. The electron flow from NADPH to Flavin, and finally to the heme of the paired nNOS subunit within a dimer, is facilitated upon calmodulin (CaM) binding. Here, we show that DLC1 binding to nNOS-CaM complex does not affect the electron transport from the reductase to the oxygenase domain. Therefore, it cannot inhibit the rate of NADPH-dependent heme reduction in nNOS, which results in L-Arginine oxidation. Also, the NO release activity does not decrease with increasing DLC1 concentration in the reaction mix, which further confirmed that DLC1 does not inhibit nNOS activity. These findings suggest that the DLC1 binding may have other implications for the nNOS function in the cell. - Highlights: • The effect of interaction of nNOS with DLC1 has been debatable with contradicting reports in literature. • Purified DLC1 has no effect on electron transport between reductase and oxygenase domain of purified nNOS-CaM. • The NO release activity of nNOS was not altered by DLC1, supporting that DLC1 does not inhibit the enzyme. • These findings suggest that the DLC1 binding may have other implications for the nNOS function in the cell.

  5. The protein inhibitor of nNOS (PIN/DLC1/LC8) binding does not inhibit the NADPH-dependent heme reduction in nNOS, a key step in NO synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Parhad, Swapnil S. [Tata Institute of Fundamental Research (TIFR), Homi Bhabha Road, Mumbai 400 005 (India); Jaiswal, Deepa [Tata Institute of Fundamental Research (TIFR), Homi Bhabha Road, Mumbai 400 005 (India); TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, Hyderabad 500075 (India); Ray, Krishanu, E-mail: krishanu@tifr.res.in [Tata Institute of Fundamental Research (TIFR), Homi Bhabha Road, Mumbai 400 005 (India); Mazumdar, Shyamalava, E-mail: shyamal@tifr.res.in [Tata Institute of Fundamental Research (TIFR), Homi Bhabha Road, Mumbai 400 005 (India)

    2016-03-25

    The neuronal nitric oxide synthase (nNOS) is an essential enzyme involved in the synthesis of nitric oxide (NO), a potent neurotransmitter. Although previous studies have indicated that the dynein light chain 1 (DLC1) binding to nNOS could inhibit the NO synthesis, the claim is challenged by contradicting reports. Thus, the mechanism of nNOS regulation remained unclear. nNOS has a heme-bearing, Cytochrome P450 core, and the functional enzyme is a dimer. The electron flow from NADPH to Flavin, and finally to the heme of the paired nNOS subunit within a dimer, is facilitated upon calmodulin (CaM) binding. Here, we show that DLC1 binding to nNOS-CaM complex does not affect the electron transport from the reductase to the oxygenase domain. Therefore, it cannot inhibit the rate of NADPH-dependent heme reduction in nNOS, which results in L-Arginine oxidation. Also, the NO release activity does not decrease with increasing DLC1 concentration in the reaction mix, which further confirmed that DLC1 does not inhibit nNOS activity. These findings suggest that the DLC1 binding may have other implications for the nNOS function in the cell. - Highlights: • The effect of interaction of nNOS with DLC1 has been debatable with contradicting reports in literature. • Purified DLC1 has no effect on electron transport between reductase and oxygenase domain of purified nNOS-CaM. • The NO release activity of nNOS was not altered by DLC1, supporting that DLC1 does not inhibit the enzyme. • These findings suggest that the DLC1 binding may have other implications for the nNOS function in the cell.

  6. Detection of HBV Covalently Closed Circular DNA

    Directory of Open Access Journals (Sweden)

    Xiaoling Li

    2017-06-01

    Full Text Available Chronic hepatitis B virus (HBV infection affects approximately 240 million people worldwide and remains a serious public health concern because its complete cure is impossible with current treatments. Covalently closed circular DNA (cccDNA in the nucleus of infected cells cannot be eliminated by present therapeutics and may result in persistence and relapse. Drug development targeting cccDNA formation and maintenance is hindered by the lack of efficient cccDNA models and reliable cccDNA detection methods. Southern blotting is regarded as the gold standard for quantitative cccDNA detection, but it is complicated and not suitable for high-throughput drug screening, so more sensitive and simple methods, including polymerase chain reaction (PCR-based methods, Invader assays, in situ hybridization and surrogates, have been developed for cccDNA detection. However, most methods are not reliable enough, and there are no unified standards for these approaches. This review will summarize available methods for cccDNA detection. It is hoped that more robust methods for cccDNA monitoring will be developed and that standard operation procedures for routine cccDNA detection in scientific research and clinical monitoring will be established.

  7. Protein covalent modification by biologically active quinones

    Directory of Open Access Journals (Sweden)

    MIROSLAV J. GASIC

    2004-11-01

    Full Text Available The avarone/avarol quinone/hydroquinone couple shows considerable antitumor activity. In this work, covalent modification of b-lactoglobulin by avarone and its derivatives as well as by the synthetic steroidal quinone 2,5(10-estradiene-1,4,17-trione and its derivatives were studied. The techniques for studying chemical modification of b-lactoglobulin by quinones were: UV/Vis spectrophotometry, SDS PAGE and isoelectrofocusing. SDS PAGE results suggest that polymerization of the protein occurs. It could be seen that the protein of 18 kD gives the bands of 20 kD, 36 kD, 40 kD, 45 kD, 64 kD and 128 kD depending on modification agent. The shift of the pI of the protein (5.4 upon modification toward lower values (from pI 5.0 to 5.3 indicated that lysine amino groups are the principal site of the reaction of b-lactoglobulin with the quinones.

  8. Covalently crosslinked diels-alder polymer networks.

    Energy Technology Data Exchange (ETDEWEB)

    Bowman, Christopher (University of Colorado, Boulder, CO); Adzima, Brian J. (University of Colorado, Boulder, CO); Anderson, Benjamin John

    2011-09-01

    This project examines the utility of cycloaddition reactions for the synthesis of polymer networks. Cycloaddition reactions are desirable because they produce no unwanted side reactions or small molecules, allowing for the formation of high molecular weight species and glassy crosslinked networks. Both the Diels-Alder reaction and the copper-catalyzed azide-alkyne cycloaddition (CuAAC) were studied. Accomplishments include externally triggered healing of a thermoreversible covalent network via self-limited hysteresis heating, the creation of Diels-Alder based photoresists, and the successful photochemical catalysis of CuAAC as an alternative to the use of ascorbic acid for the generation of Cu(I) in click reactions. An analysis of the results reveals that these new methods offer the promise of efficiently creating robust, high molecular weight species and delicate three dimensional structures that incorporate chemical functionality in the patterned material. This work was performed under a Strategic Partnerships LDRD during FY10 and FY11 as part of a Sandia National Laboratories/University of Colorado-Boulder Excellence in Science and Engineering Fellowship awarded to Brian J. Adzima, a graduate student at UC-Boulder. Benjamin J. Anderson (Org. 1833) was the Sandia National Laboratories point-of-contact for this fellowship.

  9. Study on immobilization enzyme using radiation grafting and condensation covalent

    International Nuclear Information System (INIS)

    Cao Jin; Su Zongxian; Gao Jianfeng

    1989-01-01

    The immobilization of gluecose oxidase (GOD) on polyethylene and F 46 is described by radiation grafting and condensation covalent. The GOD on polyethylene film is characterized with IR-spectrum. The results show that the enzyme activity on F 46 film is high when dose rate and covalent yield are low. When covalent yield is 4.3% the enzyme relative activity achieves the greatest value for F 46 film. The experiment also demonstrates that acrylic acid affects the relative activity of enzyme and the method of IR-pectrum character is convenient and efficient for GOD on polyethylene film

  10. Strategies to balance covalent and non-covalent biomolecule attachment within collagen-GAG biomaterials.

    Science.gov (United States)

    Pence, Jacquelyn C; Gonnerman, Emily A; Bailey, Ryan C; Harley, Brendan A C

    2014-09-01

    Strategies to integrate instructive biomolecular signals into a biomaterial are becoming increasingly complex and bioinspired. While a large majority of reports still use repeated treatments with soluble factors, this approach can be prohibitively costly and difficult to translate in vivo for applications where spatial control over signal presentation is necessary. Recent efforts have explored the use of covalent immobilization of biomolecules to the biomaterial, via both bulk (ubiquitous) as well as spatially-selective light-based crosslinking, as a means to both enhance stability and bioactivity. However, little is known about how processing conditions during immobilization impact the degree of unintended non-covalent interactions, or fouling, that takes place between the biomaterial and the biomolecule of interest. Here we demonstrate the impact of processing conditions for bulk carbodiimide (EDC) and photolithography-based benzophenone (BP) crosslinking on specific attachment vs. fouling of a model protein (Concanavalin A, ConA) within collagen-glycosaminoglycan (CG) scaffolds. Collagen source significantly impacts the selectivity of biomolecule immobilization. EDC crosslinking intensity and ligand concentration significantly impacted selective immobilization. For benzophenone photoimmobilization we observed that increased UV exposure time leads to increased ConA immobilization. Immobilization efficiency for both EDC and BP strategies was maximal at physiological pH. Increasing ligand concentration during immobilization process led to enhanced immobilization for EDC chemistry, no impact on BP immobilization, but significant increases in non-specific fouling. Given recent efforts to covalently immobilize biomolecules to a biomaterial surface to enhance bioactivity, improved understanding of the impact of crosslinking conditions on selective attachment versus non-specific fouling will inform the design of instructive biomaterials for applications across tissue

  11. Thermoelectric properties of doped BaHfO_3

    International Nuclear Information System (INIS)

    Dixit, Chandra Kr.; Bhamu, K. C.; Sharma, Ramesh

    2016-01-01

    We have studied the structural stability, electronic structure, optical properties and thermoelectric properties of doped BaHfO_3 by full potential linearized augmented plane wave (FP-LAPW) method. The electronic structure of BaHfO_3 doped with Sr shows enhances the indirect band gaps of 3.53 eV, 3.58 eV. The charge density plots show strong ionic bonding in Ba-Hf, and ionic and covalent bonding between Hf and O. Calculations of the optical spectra, viz., the dielectric function, refractive index and extinction coefficient are performed for the energy range are calculated and analyzed. Thermoelectric properties of semi conducting are also reported first time. The doped BaHfO_3 is approximately wide band gap semiconductor with the large p-type Seebeck coefficient. The power factor of BaHfO_3 is increased with Sr doping, decreases because of low electrical resistivity and thermal conductivity.

  12. Versatile and Tunable Transparent Conducting Electrodes Based on Doped Graphene

    KAUST Repository

    Mansour, Ahmed

    2016-01-01

    Herein, we explore non-covalent doping routes of CVD FLG, such as surface doping, intercalation and combination thereof, through in-depth and systematic characterization of the electrical transport properties and energy levels shifts. The intercalation of FLG with Br2 and FeCl3 is demonstrated, showing the highest improvements of the figure of merit of TCEs of any doping scheme, which results from up to a five-fold increase in conductivity while maintaining the transmittance within 3% of that for the pristine value. Importantly the intercalation yields TCEs that are air-stable, due to encapsulation of the intercalant in the bulk of FLG. Surface doping with novel solution-processed metal-organic molecular species (n- and p-type) is demonstrated with an unprecedented range of work function modulation, resulting from electron transfer and the formation of molecular surface dipoles. However, the conductivity increases compared modestly to intercalation as the electron transfer is limited to the uppermost graphene layers. Finally, a novel and universal multi-modal doping strategy is developed, thanks to the unique platform offered by FLG, where surface and intercalation doping are combined to mutually achieve high conductivity with an extended tunability of the work function. This work presents doped-FLG as a prospective and versatile candidate among emerging TCEs, given the need for efficient and stable doping routes capable of controllably tuning its properties to meet the criteria of a broad range of applications.

  13. Micro and macro scratch and microhardness study of biocompatible DLC and TiO.sub.2./sub. films prepared by laser

    Czech Academy of Sciences Publication Activity Database

    Mikšovský, Jan; Lukeš, J.; Tolde, Z.; Remsa, Jan; Kocourek, Tomáš; Jelínek, Miroslav

    2013-01-01

    Roč. 647, JAN (2013), 25-29 ISSN 1022-6680 Institutional support: RVO:68378271 Keywords : thin films * adhesion * scratch test * microhardness * Young ´s modulus * diamond-like-carbon (DLC) * titanium dioxide (TiO 2 ). Subject RIV: BM - Solid Matter Physics ; Magnetism

  14. Modified DLC coatings prepared in a large-scale reactor by dual microwave/pulsed-DC plasma-activated chemical vapour deposition

    International Nuclear Information System (INIS)

    Corbella, C.; Bialuch, I.; Kleinschmidt, M.; Bewilogua, K.

    2008-01-01

    Diamond-Like Carbon (DLC) films find abundant applications as hard and protective coatings due to their excellent mechanical and tribological performances. The addition of new elements to the amorphous DLC matrix tunes the properties of this material, leading to an extension of its scope of applications. In order to scale up their production to a large plasma reactor, DLC films modified by silicon and oxygen additions have been grown in an industrial plant of 1m 3 by means of pulsed-DC plasma-activated chemical vapour deposition (PACVD). The use of an additional microwave (MW) source has intensified the glow discharge, partly by electron cyclotron resonance (ECR), accelerating therefore the deposition process. Hence, acetylene, tetramethylsilane (TMS) and hexamethyldisiloxane (HMDSO) constituted the respective gas precursors for the deposition of a-C:H (DLC), a-C:H:Si and a-C:H:Si:O films by dual MW/pulsed-DC PACVD. This work presents systematic studies of the deposition rate, hardness, adhesion, abrasive wear and water contact angle aimed to optimize the technological parameters of deposition: gas pressure, relative gas flow of the monomers and input power. This study has been completed with measures of the atomic composition of the samples. Deposition rates around 1 μm/h, typical for standard processes held in the large reactor, were increased about by a factor 10 when the ionization source has been operated in ECR mode

  15. Electrical properties of cadmium telluride films doped with antimony

    International Nuclear Information System (INIS)

    Atdaev, B.S.; Garyagdyev, G.; Grin', V.F.; Noskov, A.I.

    1989-01-01

    Effect of cadmium telluride doping with antimony on electric and photoelectric properties is investigated. Temperature dependence of dark (σ d ) and photoconductivity (σ p ) during excitation from the range of proper absorption in the temperature range 77-300 K and spectral distribution of photoconductivity at 300 K are investigated. It is shown that in the process of doping antimony diffusses intensively over CdTe grain boundaries, decreasing potential barriers between them and due to diffusion into CdTe grains it changes their electrical properties. The acceptor character of antimony impurity can be caused by antimony diffusion into tellurium sublattice owing to proximity of their ionic and covalent radii

  16. Predominantly ligand guided non-covalently linked assemblies of ...

    Indian Academy of Sciences (India)

    JUBARAJ B BARUAH

    2018-05-12

    May 12, 2018 ... Abstract. Various non-covalently linked inorganic self-assemblies formed by the supramolecular interacting .... metal-organic frameworks.59 Inorganic chemists rou- ...... two-dimensional organic–inorganic layered perovskite.

  17. Molecular electrostatic potential analysis of non-covalent complexes

    Indian Academy of Sciences (India)

    Chemical Sciences and Technology Division and Academy of Scientific & Innovative Research (AcSIR), ... workers proposed the electrostatic-covalent model of hydrogen bonding. ..... tain degree of electron donation and acceptance occurs.

  18. Gene doping.

    Science.gov (United States)

    Haisma, H J; de Hon, O

    2006-04-01

    Together with the rapidly increasing knowledge on genetic therapies as a promising new branch of regular medicine, the issue has arisen whether these techniques might be abused in the field of sports. Previous experiences have shown that drugs that are still in the experimental phases of research may find their way into the athletic world. Both the World Anti-Doping Agency (WADA) and the International Olympic Committee (IOC) have expressed concerns about this possibility. As a result, the method of gene doping has been included in the list of prohibited classes of substances and prohibited methods. This review addresses the possible ways in which knowledge gained in the field of genetic therapies may be misused in elite sports. Many genes are readily available which may potentially have an effect on athletic performance. The sporting world will eventually be faced with the phenomena of gene doping to improve athletic performance. A combination of developing detection methods based on gene arrays or proteomics and a clear education program on the associated risks seems to be the most promising preventive method to counteract the possible application of gene doping.

  19. Covalent and non-covalent chemical engineering of actin for biotechnological applications.

    Science.gov (United States)

    Kumar, Saroj; Mansson, Alf

    2017-11-15

    The cytoskeletal filaments are self-assembled protein polymers with 8-25nm diameters and up to several tens of micrometres length. They have a range of pivotal roles in eukaryotic cells, including transportation of intracellular cargoes (primarily microtubules with dynein and kinesin motors) and cell motility (primarily actin and myosin) where muscle contraction is one example. For two decades, the cytoskeletal filaments and their associated motor systems have been explored for nanotechnological applications including miniaturized sensor systems and lab-on-a-chip devices. Several developments have also revolved around possible exploitation of the filaments alone without their motor partners. Efforts to use the cytoskeletal filaments for applications often require chemical or genetic engineering of the filaments such as specific conjugation with fluorophores, antibodies, oligonucleotides or various macromolecular complexes e.g. nanoparticles. Similar conjugation methods are also instrumental for a range of fundamental biophysical studies. Here we review methods for non-covalent and covalent chemical modifications of actin filaments with focus on critical advantages and challenges of different methods as well as critical steps in the conjugation procedures. We also review potential uses of the engineered actin filaments in nanotechnological applications and in some key fundamental studies of actin and myosin function. Finally, we consider possible future lines of investigation that may be addressed by applying chemical conjugation of actin in new ways. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  20. Hydrogels Based on Dynamic Covalent and Non Covalent Bonds: A Chemistry Perspective

    Directory of Open Access Journals (Sweden)

    Francesco Picchioni

    2018-03-01

    Full Text Available Hydrogels based on reversible covalent bonds represent an attractive topic for research at both academic and industrial level. While the concept of reversible covalent bonds dates back a few decades, novel developments continue to appear in the general research area of gels and especially hydrogels. The reversible character of the bonds, when translated at the general level of the polymeric network, allows reversible interaction with substrates as well as responsiveness to variety of external stimuli (e.g., self-healing. These represent crucial characteristics in applications such as drug delivery and, more generally, in the biomedical world. Furthermore, the several possible choices that can be made in terms of reversible interactions generate an almost endless number of possibilities in terms of final product structure and properties. In the present work, we aim at reviewing the latest developments in this field (i.e., the last five years by focusing on the chemistry of the systems at hand. As such, this should allow molecular designers to develop a toolbox for the synthesis of new systems with tailored properties for a given application.

  1. Role of direct covalent bonding in enhanced heat dissipation property of flexible graphene oxide–carbon nanotube hybrid film

    International Nuclear Information System (INIS)

    Hwang, Yongseon; Kim, Myeongjin; Kim, Jooheon

    2013-01-01

    The thermal conductivity of graphene oxide/multiwalled carbon nanotube (GO/MWCNT) hybrid films with and without covalent bonding is examined in this study. To fabricate chemically bonded GO/MWCNT hybrid films, chlorinated GO and amino-functionalized MWCNTs are bonded covalently. The mixtures of surface modified GO and MWCNT were filtered and then subjected to hot pressing to fabricate stacked films. Examination of these chemically bonded hybrid films reveal that chlorine-doped GO exhibits enhanced electrical properties because it creates hole charge carriers by attracting the electrons in GO towards chlorine. Enhanced electrical conductivity and low sheet resistance are observed also with increasing MWCNT loadings. On comparing the through-plane thermal properties, the chemically bonded hybrid films were found to exhibit higher thermal conductivity than do the physically bonded hybrid films because of the synergetic interaction of functional groups in GO and MWCNTs in the former films. However, excess addition of MWCNTs to the films leads to an increasing phonon scattering density and a decreased thermal conductivity. - Highlights: • Graphene oxide/carbon nanotube (GO/CNT) films are bonded covalently. • GO/CNT hybrid films are prepared through filtering and hot-pressing method. • Chemically bonded hybrid films exhibit enhanced electrical and thermal properties. • Enhanced thermal conductivity is explained according to increasing CNT contents

  2. Characterization of Metal-Doped Methylated Microporous Silica for Molecular Separations

    DEFF Research Database (Denmark)

    El-Feky, Hany Hassan; Briceno, Kelly; Szalata, Kamila

    2015-01-01

    Novel silica xerogels are prepared and developed by sol-gel method in the present study. The preparation involves cobalt-doping within the organic templated silica matrices, where methyltriethoxysilane (MTES), which contains methyl groups as a covalently bonded organic template is used. The synth...

  3. Oxygen Evolution at Manganite Perovskite Ruddlesden-Popper Type Particles: Trends of Activity on Structure, Valence and Covalence

    Directory of Open Access Journals (Sweden)

    Majid Ebrahimizadeh Abrishami

    2016-11-01

    Full Text Available An improved understanding of the correlation between the electronic properties of Mn-O bonds, activity and stability of electro-catalysts for the oxygen evolution reaction (OER is of great importance for an improved catalyst design. Here, an in-depth study of the relation between lattice structure, electronic properties and catalyst performance of the perovskite Ca1−xPrxMnO3 and the first-order RP-system Ca2−xPrxMnO4 at doping levels of x = 0, 0.25 and 0.5 is presented. Lattice structure is determined by X-ray powder diffraction and Rietveld refinement. X-ray absorption spectroscopy of Mn-L and O-K edges gives access to Mn valence and covalency of the Mn-O bond. Oxygen evolution activity and stability is measured by rotating ring disc electrode studies. We demonstrate that the highest activity and stability coincidences for systems with a Mn-valence state of +3.7, though also requiring that the covalency of the Mn-O bond has a relative minimum. This observation points to an oxygen evolution mechanism with high redox activity of Mn. Covalency should be large enough for facile electron transfer from adsorbed oxygen species to the MnO6 network; however, it should not be hampered by oxidation of the lattice oxygen, which might cause a crossover to material degradation. Since valence and covalency changes are not entirely independent, the introduction of the energy position of the eg↑ pre-edge peak in the O-K spectra as a new descriptor for oxygen evolution is suggested, leading to a volcano-like representation of the OER activity.

  4. Theory and Applications of Covalent Docking in Drug Discovery: Merits and Pitfalls

    Directory of Open Access Journals (Sweden)

    Hezekiel Mathambo Kumalo

    2015-01-01

    Full Text Available he present art of drug discovery and design of new drugs is based on suicidal irreversible inhibitors. Covalent inhibition is the strategy that is used to achieve irreversible inhibition. Irreversible inhibitors interact with their targets in a time-dependent fashion, and the reaction proceeds to completion rather than to equilibrium. Covalent inhibitors possessed some significant advantages over non-covalent inhibitors such as covalent warheads can target rare, non-conserved residue of a particular target protein and thus led to development of highly selective inhibitors, covalent inhibitors can be effective in targeting proteins with shallow binding cleavage which will led to development of novel inhibitors with increased potency than non-covalent inhibitors. Several computational approaches have been developed to simulate covalent interactions; however, this is still a challenging area to explore. Covalent molecular docking has been recently implemented in the computer-aided drug design workflows to describe covalent interactions between inhibitors and biological targets. In this review we highlight: (i covalent interactions in biomolecular systems; (ii the mathematical framework of covalent molecular docking; (iii implementation of covalent docking protocol in drug design workflows; (iv applications covalent docking: case studies and (v shortcomings and future perspectives of covalent docking. To the best of our knowledge; this review is the first account that highlights different aspects of covalent docking with its merits and pitfalls. We believe that the method and applications highlighted in this study will help future efforts towards the design of irreversible inhibitors.

  5. A covalent attraction between two molecular cation TTF·~+

    Institute of Scientific and Technical Information of China (English)

    WANG FangFang; WANG Yi; WANG BingQiang; WANG YinFeng; MA Fang; Li ZhiRu

    2009-01-01

    The optimized structure of the tetrathiafulvalence radical-cation dimer (TTF·~+-TTF·~+) with all-real frequencies is obtained at MP2/6-311G level,which exhibits the attraction between two molecular cation TTF·~+.The new attraction interaction is a 20-center-2-electron intermolecular covalent π/π bonding with a telescope shape.The covalent π/π bonding has the bonding energy of about-21 kcal·mol~(-1) and is concealed by the Coulombic repulsion between two TTF·~+ cations.This intermolecular covalent attraction also influences the structure of the TTF·~+ subunit,I.e.,its molecular plane is bent by an angle θ=5.6°.This work provides new knowledge on intermolecular interaction.

  6. A covalent attraction between two molecular cation TTF·~+

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The optimized structure of the tetrathiafulvalence radical-cation dimer(TTF·+-TTF·+) with all-real frequencies is obtained at MP2/6-311G level,which exhibits the attraction between two molecular cation TTF·+.The new attraction interaction is a 20-center-2-electron intermolecular covalent π /π bonding with a telescope shape.The covalent π /π bonding has the bonding energy of about -21 kcal·mol-1 and is concealed by the Coulombic repulsion between two TTF·+ cations.This intermolecular covalent attraction also influences the structure of the TTF·+ subunit,i.e.,its molecular plane is bent by an angle θ=5.6°.This work provides new knowledge on intermolecular interaction.

  7. Nitrogen-Doped Three Dimensional Graphene for Electrochemical Sensing.

    Science.gov (United States)

    Yan, Jing; Chen, Ruwen; Liang, Qionglin; Li, Jinghong

    2015-07-01

    The rational assembly and doping of graphene play an crucial role in the improvement of electrochemical performance for analytical applications. Covalent assembly of graphene into ordered hierarchical structure provides an interconnected three dimensional conductive network and large specific area beneficial to electrolyte transfer on the electrode surface. Chemical doping with heteroatom is a powerful tool to intrinsically modify the electronic properties of graphene due to the increased free charge-carrier densities. By incorporating covalent assembly and nitrogen doping strategy, a novel nitrogen doped three dimensional reduced graphene oxide nanostructure (3D-N-RGO) was developed with synergetic enhancement in electrochemical behaviors. The as prepared 3D-N-RGO was further applied for catechol detection by differential pulse voltammetry. It exhibits much higher electrocatalytic activity towards catechol with increased peak current and decreased potential difference between the oxidation and reduction peaks. Owing to the improved electro-chemical properties, the response of the electrochemical sensor varies linearly with the catechol concentrations ranging from 5 µM to 100 µM with a detection limit of 2 µM (S/N = 3). This work is promising to open new possibilities in the study of novel graphene nanostructure and promote its potential electrochemical applications.

  8. Covalent modification and exfoliation of graphene oxide using ferrocene

    Science.gov (United States)

    Avinash, M. B.; Subrahmanyam, K. S.; Sundarayya, Y.; Govindaraju, T.

    2010-09-01

    Large scale preparation of single-layer graphene and graphene oxide is of great importance due to their potential applications. We report a simple room temperature method for the exfoliation of graphene oxide using covalent modification of graphene oxide with ferrocene to obtain single-layer graphene oxide sheets. The samples were characterized by FESEM, HRTEM, AFM, EDAX, FT-IR, Raman and Mössbauer spectroscopic studies. HRTEM micrograph of the covalently modified graphene oxide showed increased interlayer spacing of ~2.4 nm due to ferrocene intercalation. The presence of single-layer graphene oxide sheets were confirmed by AFM studies. The covalently modified ferrocene-graphene oxide composite showed interesting magnetic behavior.Large scale preparation of single-layer graphene and graphene oxide is of great importance due to their potential applications. We report a simple room temperature method for the exfoliation of graphene oxide using covalent modification of graphene oxide with ferrocene to obtain single-layer graphene oxide sheets. The samples were characterized by FESEM, HRTEM, AFM, EDAX, FT-IR, Raman and Mössbauer spectroscopic studies. HRTEM micrograph of the covalently modified graphene oxide showed increased interlayer spacing of ~2.4 nm due to ferrocene intercalation. The presence of single-layer graphene oxide sheets were confirmed by AFM studies. The covalently modified ferrocene-graphene oxide composite showed interesting magnetic behavior. Electronic supplementary information (ESI) available: Magnetic data; AFM images; TEM micrographs; and Mössbauer spectroscopic data. See DOI: 10.1039/c0nr00024h

  9. Covalent and non-covalent curcumin loading in acid-responsive polymeric micellar nanocarriers

    Science.gov (United States)

    Gao, Min; Chen, Chao; Fan, Aiping; Zhang, Ju; Kong, Deling; Wang, Zheng; Zhao, Yanjun

    2015-07-01

    Poor aqueous solubility, potential degradation, rapid metabolism and elimination lead to low bioavailability of pleiotropic impotent curcumin. Herein, we report two types of acid-responsive polymeric micelles where curcumin was encapsulated via both covalent and non-covalent modes for enhanced loading capacity and on-demand release. Biodegradable methoxy poly(ethylene glycol)-poly(lactic acid) copolymer (mPEG-PLA) was conjugated with curcumin via a hydrazone linker, generating two conjugates differing in architecture (single-tail versus double-tail) and free curcumin was encapsulated therein. The two micelles exhibited similar hydrodynamic size at 95 ± 3 nm (single-tail) and 96 ± 3 nm (double-tail), but their loading capacities differed significantly at 15.0 ± 0.5% (w/w) (single-tail) and 4.8 ± 0.5% (w/w) (double-tail). Under acidic sink conditions (pH 5.0 and 6.0), curcumin displayed a faster release from the single-tail nanocarrier, which was correlated to a low IC50 of 14.7 ± 1.6 (μg mL-1) compared to the value of double-tail micelle (24.9 ± 1.3 μg mL-1) in HeLa cells. The confocal imaging and flow cytometry analysis demonstrated a superior capability of single-tail micelle for intracellular curcumin delivery, which was a consequence of the higher loading capacity and lower degree of mPEG surface coverage. In conclusion, the dual loading mode is an effective means to increase the drug content in the micellar nanocarriers whose delivery efficiency is highly dependent on its polymer-drug conjugate architecture. This strategy offers an alternative nanoplatform for intracellularly delivering impotent hydrophobic agents (i.e. curcumin) in an efficient stimuli-triggered way, which is valuable for the enhancement of curcumin’s efficacy in managing a diverse range of disorders.

  10. Covalent and non-covalent curcumin loading in acid-responsive polymeric micellar nanocarriers

    International Nuclear Information System (INIS)

    Gao, Min; Chen, Chao; Fan, Aiping; Wang, Zheng; Zhao, Yanjun; Zhang, Ju; Kong, Deling

    2015-01-01

    Poor aqueous solubility, potential degradation, rapid metabolism and elimination lead to low bioavailability of pleiotropic impotent curcumin. Herein, we report two types of acid-responsive polymeric micelles where curcumin was encapsulated via both covalent and non-covalent modes for enhanced loading capacity and on-demand release. Biodegradable methoxy poly(ethylene glycol)-poly(lactic acid) copolymer (mPEG-PLA) was conjugated with curcumin via a hydrazone linker, generating two conjugates differing in architecture (single-tail versus double-tail) and free curcumin was encapsulated therein. The two micelles exhibited similar hydrodynamic size at 95 ± 3 nm (single-tail) and 96 ± 3 nm (double-tail), but their loading capacities differed significantly at 15.0 ± 0.5% (w/w) (single-tail) and 4.8 ± 0.5% (w/w) (double-tail). Under acidic sink conditions (pH 5.0 and 6.0), curcumin displayed a faster release from the single-tail nanocarrier, which was correlated to a low IC_5_0 of 14.7 ± 1.6 (μg mL"−"1) compared to the value of double-tail micelle (24.9 ± 1.3 μg mL"−"1) in HeLa cells. The confocal imaging and flow cytometry analysis demonstrated a superior capability of single-tail micelle for intracellular curcumin delivery, which was a consequence of the higher loading capacity and lower degree of mPEG surface coverage. In conclusion, the dual loading mode is an effective means to increase the drug content in the micellar nanocarriers whose delivery efficiency is highly dependent on its polymer–drug conjugate architecture. This strategy offers an alternative nanoplatform for intracellularly delivering impotent hydrophobic agents (i.e. curcumin) in an efficient stimuli-triggered way, which is valuable for the enhancement of curcumin’s efficacy in managing a diverse range of disorders. (paper)

  11. Construction of covalently coupled, concatameric dimers of 7TM receptors

    DEFF Research Database (Denmark)

    Terpager, Marie; Scholl, D Jason; Kubale, Valentina

    2009-01-01

    -Ala repeats flanked by flexible spacers and positively charged residues to ensure correct inside-out orientation plus an extracellular HA-tag to construct covalently coupled dimers of 7TM receptors. Such 15 TM concatameric homo- and heterodimers of the beta(2)-adrenergic and the NK(1) receptors, which...... for either of the protomers, which was not observed upon simple coexpression of the two receptors. It is concluded that covalently joined 7TM receptor dimers with surprisingly normal receptor properties can be constructed with use of an artificial transmembrane connector, which perhaps can be used to fuse...

  12. Isothermal and dynamic oxidation behaviour of Mo-W doped carbon-based coating

    Science.gov (United States)

    Mandal, Paranjayee; Ehiasarian, Arutiun P.; Hovsepian, Papken Eh.

    2015-10-01

    The oxidation behaviour of Mo-W doped carbon-based coating (Mo-W-C) is investigated in elevated temperature (400-1000 °C). Strong metallurgical bond between Mo-W-C coating and substrate prevents any sort of delamination during heat-treatment. Isothermal oxidation tests show initial growth of metal oxides at 500 °C, however graphitic nature of the as-deposited coating is preserved. The oxidation progresses with further rise in temperature and the substrate is eventually exposed at 700 °C. The performance of Mo-W-C coating is compared with a state-of-the-art DLC(Cr/Cr-WC/W:C-H/a:C-H) coating, which shows preliminary oxidation at 400 °C and local delamination of the coating at 500 °C leading to substrate exposure. The graphitisation starts at 400 °C and the diamond-like structure is completely converted into the graphite-like structure at 500 °C. Dynamic oxidation behaviour of both the coatings is investigated using Thermo-gravimetric analysis carried out with a slow heating rate of 1 °C/min from ambient temperature to 1000 °C. Mo-W-C coating resists oxidation up to ˜800 °C whereas delamination of DLC(Cr/Cr-WC/W:C-H/a:C-H) coating is observed beyond ˜380 °C. In summary, Mo-W-C coating provides improved oxidation resistance at elevated temperature compared to DLC(Cr/Cr-WC/W:C-H/a:C-H) coating.

  13. Controllable synthesizing DLC nano structures as a super hydrophobic layer on cotton fabric using a low-cost ethanol electrospray-assisted atmospheric plasma jet

    Science.gov (United States)

    Sohbatzadeh, F.; Eshghabadi, M.; Mohsenpour, T.

    2018-06-01

    The surface modification of cotton samples was carried out using a liquid (ethanol) electrospray-assisted atmospheric pressure plasma jet. X-ray photoelectron spectroscopy (XPS) and Raman analysis confirmed the successful deposition of diamond like carbon (DLC) nano structures on the cotton surface. The super hydrophobic state of the samples was probed by contact angle measurements. The water repellency of the layers was tuned by controlling the voltage applied to the electrospray electrode. An investigation of the morphological and chemical structures of the samples by field emission scanning microscopy, atomic force microscopy (AFM) and XPS indicated that the physical shape, distribution and amorphization of the DLC structures were successfully adjusted and improved by applying a voltage to the electrospray electrode. Finally wash durability of the best sample was tested for 35 cycles. In this work, the use of a well-developed atmospheric pressure plasma jet for DLC nano structures deposition can enable a promising environmentally friendly and low-cost approach for modifying cotton fabrics for super water-repellent fabric applications.

  14. Friction and wear behaviour of Mo–W doped carbon-based coating during boundary lubricated sliding

    International Nuclear Information System (INIS)

    Hovsepian, Papken Eh.; Mandal, Paranjayee; Ehiasarian, Arutiun P.; Sáfrán, G.; Tietema, R.; Doerwald, D.

    2016-01-01

    Graphical abstract: - Highlights: • Novel Mo–W–C coating provides extremely low friction (μ ∼ 0.03) in lubricated condition. • Mo–W–C outperforms existing DLCs in terms of low friction, independent of temperature. • Tribochemical reactions govern the wear mechanism of Mo–W–C coating. • The transfer layer contains graphitic carbon and ‘in situ’ formed WS 2 and MoS 2 . • WS 2 and MoS 2 are the key factors facilitating appreciably low friction and wear rate. - Abstract: A molybdenum and tungsten doped carbon-based coating (Mo–W–C) was developed in order to provide low friction in boundary lubricated sliding condition at ambient and at high temperature. The Mo–W–C coating showed the lowest friction coefficient among a number of commercially available state-of-the-art DLC coatings at ambient temperature. At elevated temperature (200 °C), Mo–W–C coating showed a significant reduction in friction coefficient with sliding distance in contrast to DLC coatings. Raman spectroscopy revealed the importance of combined Mo and W doping for achieving low friction at both ambient and high temperature. The significant decrease in friction and wear rate was attributed to the presence of graphitic carbon debris (from coating) and ‘in situ’ formed metal sulphides (WS 2 and MoS 2 , where metals were supplied from coating and sulphur from engine oil) in the transfer layer.

  15. Friction and wear behaviour of Mo–W doped carbon-based coating during boundary lubricated sliding

    Energy Technology Data Exchange (ETDEWEB)

    Hovsepian, Papken Eh., E-mail: p.hovsepian@shu.ac.uk [Nanotechnology Centre for PVD Research, HIPIMS Research Centre, Sheffield Hallam University, City Campus, Howard Street, Sheffield S1 1WB (United Kingdom); Mandal, Paranjayee, E-mail: 200712mum@gmail.com [Nanotechnology Centre for PVD Research, HIPIMS Research Centre, Sheffield Hallam University, City Campus, Howard Street, Sheffield S1 1WB (United Kingdom); Ehiasarian, Arutiun P., E-mail: a.ehiasarian@shu.ac.uk [Nanotechnology Centre for PVD Research, HIPIMS Research Centre, Sheffield Hallam University, City Campus, Howard Street, Sheffield S1 1WB (United Kingdom); Sáfrán, G., E-mail: safran.gyorgy@ttk.mta.hu [Institute for Technical Physics and Materials Science, Centre for Energy Research, Hungarian Academy of Sciences, H-1121 Budapest, Konkoly-Thegeut 29-33 (Hungary); Tietema, R., E-mail: rtietema@hauzer.nl [IHI Hauzer Techno Coating B.V., Van Heemskerckweg 22, 5928 LL Venlo (Netherlands); Doerwald, D., E-mail: ddoerwald@hauzer.nl [IHI Hauzer Techno Coating B.V., Van Heemskerckweg 22, 5928 LL Venlo (Netherlands)

    2016-03-15

    Graphical abstract: - Highlights: • Novel Mo–W–C coating provides extremely low friction (μ ∼ 0.03) in lubricated condition. • Mo–W–C outperforms existing DLCs in terms of low friction, independent of temperature. • Tribochemical reactions govern the wear mechanism of Mo–W–C coating. • The transfer layer contains graphitic carbon and ‘in situ’ formed WS{sub 2} and MoS{sub 2}. • WS{sub 2} and MoS{sub 2} are the key factors facilitating appreciably low friction and wear rate. - Abstract: A molybdenum and tungsten doped carbon-based coating (Mo–W–C) was developed in order to provide low friction in boundary lubricated sliding condition at ambient and at high temperature. The Mo–W–C coating showed the lowest friction coefficient among a number of commercially available state-of-the-art DLC coatings at ambient temperature. At elevated temperature (200 °C), Mo–W–C coating showed a significant reduction in friction coefficient with sliding distance in contrast to DLC coatings. Raman spectroscopy revealed the importance of combined Mo and W doping for achieving low friction at both ambient and high temperature. The significant decrease in friction and wear rate was attributed to the presence of graphitic carbon debris (from coating) and ‘in situ’ formed metal sulphides (WS{sub 2} and MoS{sub 2}, where metals were supplied from coating and sulphur from engine oil) in the transfer layer.

  16. Covalent microcontact printing of proteins fro cell patterning

    NARCIS (Netherlands)

    Rozkiewicz, D.I.; Kraan, Yvonne M.; Werten, Marc W.T.; de Wolf, Frits A.; Subramaniam, Vinod; Ravoo, B.J.; Reinhoudt, David

    2006-01-01

    We describe a straightforward approach to the covalent immobilization of cytophilic proteins by microcontact printing, which can be used to pattern cells on substrates. Cytophilic proteins are printed in micropatterns on reactive self-assembled monolayers by using imine chemistry. An

  17. Capillary electrophoresis of covalently functionalized single-chirality carbon nanotubes.

    Science.gov (United States)

    He, Pingli; Meany, Brendan; Wang, Chunyan; Piao, Yanmei; Kwon, Hyejin; Deng, Shunliu; Wang, YuHuang

    2017-07-01

    We demonstrate the separation of chirality-enriched single-walled carbon nanotubes (SWCNTs) by degree of surface functionalization using high-performance CE. Controlled amounts of negatively charged and positively charged functional groups were attached to the sidewall of chirality-enriched SWCNTs through covalent functionalization using 4-carboxybenzenediazonium tetrafluoroborate or 4-diazo-N,N-diethylaniline tetrafluoroborate, respectively. Surfactant- and pH-dependent studies confirmed that under conditions that minimized ionic screening effects, separation of these functionalized SWCNTs was strongly dependent on the surface charge density introduced through covalent surface chemistry. For both heterogeneous mixtures and single-chirality-enriched samples, covalently functionalized SWCNTs showed substantially increased peak width in electropherogram spectra compared to nonfunctionalized SWCNTs, which can be attributed to a distribution of surface charges along the functionalized nanotubes. Successful separation of functionalized single-chirality SWCNTs by functional density was confirmed with UV-Vis-NIR absorption and Raman scattering spectroscopies of fraction collected samples. These results suggest a high degree of structural heterogeneity in covalently functionalized SWCNTs, even for chirality-enriched samples, and show the feasibility of applying CE for high-performance separation of nanomaterials based on differences in surface functional density. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. COVAL, Compound Probability Distribution for Function of Probability Distribution

    International Nuclear Information System (INIS)

    Astolfi, M.; Elbaz, J.

    1979-01-01

    1 - Nature of the physical problem solved: Computation of the probability distribution of a function of variables, given the probability distribution of the variables themselves. 'COVAL' has been applied to reliability analysis of a structure subject to random loads. 2 - Method of solution: Numerical transformation of probability distributions

  19. Covalent Attachment of Bent-Core Mesogens to Silicon Surfaces

    NARCIS (Netherlands)

    Scheres, L.; Achten, R.; Giesbers, M.; Smet, de L.; Arafat, A.; Sudhölter, E.J.R.; Marcelis, A.T.M.; Zuilhof, H.

    2009-01-01

    Two vinyl-terminated bent core-shaped liquid crystalline molecules that exhibit thermotropic antiferroelectric SmCPA phases have been covalently attached onto a hydrogen-terminated silicon(111) surface. The surface attachment was achieved via a mild procedure from a mesitylene solution, using

  20. Multi-step non-covalent pathways to supramolecular systems

    NARCIS (Netherlands)

    Hermans, T.M.

    2010-01-01

    The spontaneous organization of building blocks into ordered structures governed by non-covalent interactions, or self-assembly, is a commonly encountered pathway in nature to obtain functional materials. These materials often consist of many different components ordered into intricate structures.

  1. Covalent Functionalization of Carbon Nanotube by Tetrasubtituted Amino Manganese Phthalocyanine

    Institute of Scientific and Technical Information of China (English)

    Zheng Long YANG; Hong Zheng CHEN; Lei CAO; Han Yin LI; Mang WANG

    2004-01-01

    The multiwall carbon nanotube (MWCNT) bonded to 2, 9, 16, 23-tetraamino manganese phthalocyanine (TAMnPc) was obtained by covalent functionalization, and its chemical structure was characterized by TEM. The photoconductivity of single-layered photoreceptors, where MWCNT bonded by TAMnPc (MWCNT-b-TAMnPc) served as the charge generation material (CGM), was also studied.

  2. Double Dynamic Supramolecular Polymers of Covalent Oligo-Dynamers

    NARCIS (Netherlands)

    Schaeffer, Gaël; Buhler, Eric; Candau, Sauveur Jean; Lehn, Jean-Marie

    2013-01-01

    Double-dynamic polymers, incorporating both molecular and supramolecular dynamic features (“double dynamers”) have been generated, where these functions are present in a nonstoichiometric ratio in the main chain of the polymer. It has been achieved by (1) the formation of covalent oligo-dynamers in

  3. Covalent bindings in proteins following UV-C irradiation

    International Nuclear Information System (INIS)

    Diezel, W.; Meffert, H.; Soennichsen, N.; Reinicke, C.

    1980-01-01

    Following a UV-C irradiation of catalase cross-linked catalase subunits could be detected by sodium dodecylsulfate gel electrophoresis. The subunits of aldolase were not cross-linked. The origin of covalent bindings in the catalase molecule is suggested to be effected by a free radical chain reaction induced by the heme component of catalase after UV-C irradiation. (author)

  4. Caracterización de recubrimientos DLC/Si bajo la influencia de un fluido biológico simulado

    Directory of Open Access Journals (Sweden)

    William Vargas

    2016-01-01

    Full Text Available Uno de los materiales más usados como biomaterial es el acero 316LVM; sin embargo, presenta complicaciones al trabajarlo como reemplazo permanente, debido a que libera iones metálicos a los tejidos, generando aumento en el número de intervenciones que deben realizarse; ante esto, se estudia cómo mejorar el comportamiento de materiales convencionales mediante recubrimientos que elevan sus propiedades mecánicas y anticorrosivas, incrementando su vida útil. Se evaluó el comportamiento ante el fenómeno de micro-abrasión-corrosión de recubrimientos DLC/Si depositados mediante la técnica de deposición química de vapor asistida por plasma en contacto con solución de Ringer, simulando un ambiente biológico. Los resultados indican que el recubrimiento experimenta un aumento en el volumen de desgaste cuando se encuentra sometido al mecanismo de micro-abrasión-corrosión en relación con la prueba de solo microabrasión, además, la pérdida más significativa se encuentra en el sustrato sin recubrimiento; esto demuestra el efecto protector del recubrimiento.

  5. Nanostructures based in boro nitride thin films deposited by PLD onto Si/Si3N4/DLC substrate

    International Nuclear Information System (INIS)

    Roman, W S; Riascos, H; Caicedo, J C; Ospina, R; Tirado-MejIa, L

    2009-01-01

    Diamond-like carbon and boron nitride were deposited like nanostructered bilayer on Si/Si 3 N 4 substrate, both with (100) crystallographic orientation, these films were deposited through pulsed laser technique (Nd: YAG: 8 Jcm -2 , 9ns). Graphite (99.99%) and boron nitride (99.99%) targets used to growth the films in argon atmosphere. The thicknesses of bilayer were determined with a perfilometer, active vibration modes were analyzed using infrared spectroscopy (FTIR), finding bands associated around 1400 cm -1 for B - N bonding and bands around 1700 cm -1 associated with C=C stretching vibrations of non-conjugated alkenes and azometinic groups, respectively. The crystallites of thin films were analyzed using X-ray diffraction (XRD) and determinated the h-BN (0002), α-Si 3 N 4 (101) phases. The aim of this study is to relate the dependence on physical and chemical characteristics of the system Si/Si 3 N 4 /DLC/BN with gas pressure adjusted at the 1.33, 2.67 and 5.33 Pa values.

  6. Effect of additional sample bias in Meshed Plasma Immersion Ion Deposition (MPIID) on microstructural, surface and mechanical properties of Si-DLC films

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Mingzhong [State Key Laboratory of Advanced Welding & Joining, Harbin Institute of Technology, Harbin 150001 (China); School of Materials Science & Engineering, Jiamusi University, Jiamusi 154007 (China); Tian, Xiubo, E-mail: xiubotian@163.com [State Key Laboratory of Advanced Welding & Joining, Harbin Institute of Technology, Harbin 150001 (China); Li, Muqin [School of Materials Science & Engineering, Jiamusi University, Jiamusi 154007 (China); Gong, Chunzhi [State Key Laboratory of Advanced Welding & Joining, Harbin Institute of Technology, Harbin 150001 (China); Wei, Ronghua [Southwest Research Institute, San Antonio, TX 78238 (United States)

    2016-07-15

    Highlights: • A novel Meshed Plasma Immersion Ion Deposition is proposed. • The deposited Si-DLC films possess denser structures and high deposition rate. • It is attributed to ion bombardment of the deposited films. • The ion energy can be independently controlled by an additional bias (novel set up). - Abstract: Meshed Plasma Immersion Ion Deposition (MPIID) using cage-like hollow cathode discharge is a modified process of conventional PIID, but it allows the deposition of thick diamond-like carbon (DLC) films (up to 50 μm) at a high deposition rate (up to 6.5 μm/h). To further improve the DLC film properties, a new approach to the MPIID process is proposed, in which the energy of ions incident to the sample surface can be independently controlled by an additional voltage applied between the samples and the metal meshed cage. In this study, the meshed cage was biased with a pulsed DC power supply at −1350 V peak voltage for the plasma generation, while the samples inside the cage were biased with a DC voltage from 0 V to −500 V with respect to the cage to study its effect. Si-DLC films were synthesized with a mixture of Ar, C{sub 2}H{sub 2} and tetramethylsilane (TMS). After the depositions, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectrons spectroscopy (XPS), Raman spectroscopy and nanoindentation were used to study the morphology, surface roughness, chemical bonding and structure, and the surface hardness as well as the modulus of elasticity of the Si-DLC films. It was observed that the intense ion bombardment significantly densified the films, reduced the surface roughness, reduced the H and Si contents, and increased the nanohardness (H) and modulus of elasticity (E), whereas the deposition rate decreased slightly. Using the H and E data, high values of H{sup 3}/E{sup 2} and H/E were obtained on the biased films, indicating the potential excellent mechanical and tribological properties of the films. In this

  7. Ultramicroporous carbon with extremely narrow pore distribution and very high nitrogen doping for efficient methane mixture gases upgrading

    KAUST Repository

    Yao, Kexin; Chen, Yanli; Lu, Yue; Zhao, Yunfeng; Ding, Yi

    2017-01-01

    ultramicropore size (<7 Å) distributions (>95%) and high N doping contents (>10 at%) are fabricated through the pyrolysis of a perchloro-substituted porous covalent triazine-based framework (ClCTF). In particular, the sample prepared at 650 °C (ClCTF-1

  8. Study on electrical structure and magneto-optical properties of W-doped ZnO

    Science.gov (United States)

    Li, Yong; Hou, Qingyu; Zhao, Chunwang; Xu, Zhenchao

    2018-04-01

    For W-doping amounts ranging from 0.0417 to 0.0833, experimental UV-visible absorption spectra blue shift and red shift results have been reported in the literatures. However, there is few literature reported research on magnetic mechanism. To solve this problem, this study investigates the disagreement about blue shift and red shift results and research on magnetic mechanism. The band structures, density of states, absorption spectra and magnetism have been investigated using first-principles planewave ultrasoft pseudopotential method based on the density functional theory. The calculated results showed that increased W-doping amounts first increase the volumes, and then reduce the volumes, decrease the formation energies, and stabilize the doped system. The band gaps become narrower and the absorption spectrum exhibits a significant red shift in UV and visible light emission. Moreover, the covalent bond vertical to c-axis strengthens, and the ionic bond parallel to c-axis weakens. Increased W-doping amounts decrease the magnetism of doped system. The magnetism of doped system originates from the electron exchange among W-5d, O-2p and Zn-3d orbitals of the W-doped ZnO. In W double-doped system, the ferromagnetic Curie temperature can be above room temperature when the doped system has a longer W-W distance.

  9. New fluorescent pH sensors based on covalently linkable PET rhodamines

    Science.gov (United States)

    Aigner, Daniel; Borisov, Sergey M.; Orriach Fernández, Francisco J.; Fernández Sánchez, Jorge F.; Saf, Robert; Klimant, Ingo

    2012-01-01

    A new class of rhodamines for the application as indicator dyes in fluorescent pH sensors is presented. Their pH-sensitivity derives from photoinduced electron transfer between non-protonated amino groups and the excited chromophore which results in effective fluorescence quenching at increasing pH. The new indicator class carries a pentafluorophenyl group at the 9-position of the xanthene core where other rhodamines bear 2-carboxyphenyl substituents instead. The pentafluorophenyl group is used for covalent coupling to sensor matrices by “click” reaction with mercapto groups. Photophysical properties are similar to “classical” rhodamines carrying 2′-carboxy groups. pH sensors have been prepared with two different matrix materials, silica gel and poly(2-hydroxyethylmethacrylate). Both sensors show high luminescence brightness (absolute fluorescence quantum yield ΦF≈0.6) and high pH-sensitivity at pH 5–7 which makes them suitable for monitoring biotechnological samples. To underline practical applicability, a dually lifetime referenced sensor containing Cr(III)-doped Al2O3 as reference material is presented. PMID:22967541

  10. Binding matter with antimatter: the covalent positron bond.

    Science.gov (United States)

    Charry, Jorge Alfonso; Varella, Marcio T Do N; Reyes, Andrés

    2018-05-16

    We report sufficient theoretical evidence of the energy stability of the e⁺H₂²⁻ molecule, formed by two H⁻ anions and one positron. Analysis of the electronic and positronic densities of the latter compound undoubtedly points out the formation of a positronic covalent bond between the otherwise repelling hydride anions. The lower limit for the bonding energy of the e⁺H₂²⁻ molecule is 74 kJ/mol (0.77 eV), accounting for the zero-point vibrational correction. The formation of a non electronic covalent bond is fundamentally distinct from positron attachment to stable molecules, as the latter process is characterized by a positron affinity, analogous to the electron affinity. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Spectroscopic properties of highly Nd-doped lead phosphate glass

    Energy Technology Data Exchange (ETDEWEB)

    Novais, A.L.F. [Instituto de Física, Universidade Federal de Alagoas, Grupo de Fotônica e Fluidos Complexos, 57072-970 Maceió, AL (Brazil); Dantas, N.O. [Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Instituto de Física, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Guedes, I. [Departamento de Física, Universidade Federal do Ceará, Campus do PICI, Caixa Postal 6030, 60455-760 Fortaleza, CE (Brazil); Vermelho, M.V.D., E-mail: vermelho@fis.ufal.br [Instituto de Física, Universidade Federal de Alagoas, Grupo de Fotônica e Fluidos Complexos, 57072-970 Maceió, AL (Brazil)

    2015-11-05

    The spectroscopic characteristics of highly Nd{sup 3+}-doped lead phosphate glasses (xNd:Pb{sub 3}(PO{sub 4}){sub 2}) have been investigated. The X-ray spectra show that the matrices are glassy up to 25 wt% of Nd{sup 3+} doping. From the Judd–Ofelt analysis we observe that while the Ω{sub (2)} parameter remains constant indicating that the 4f{sup N} and 4f{sup N−1}5 d{sup 1} configurations are not affected by the Nd{sup 3+} doping, the behavior of both Ω{sub (4)} and Ω{sub (6)} changes for 15 wt% of Nd{sup 3+} doping. The reduction of the Ω{sub (6)} parameter is related to the increase of the covalence bonding between the ligands and the Nd{sup 3+} ions. At this particular concentration, the radiative lifetime has a four-fold enhancement. Such behaviors are likely to be related to a modification in the glass structure for high Nd{sup 3+} concentrations. - Graphical abstract: Highly doped lead-phosphate glass matrix, with nominal concentration of up to 25 wt%, maintain the spectroscopic properties without deterioration. The analysis concerning the point of view of Nd{sup 3+} ions showed that high concentrations only affects the rare earth electronic charge density distribution. - Highlights: • Spectroscopic characterization of Nd{sub 2}O{sub 3} highly doped lead phosphate glasses. • Phosphate glass doped with Nd{sup 3+} for applications in photonic devices. • Judd–Ofelt analysis in phosphate glasses doped with Neodymium.

  12. Doped Organic Transistors.

    Science.gov (United States)

    Lüssem, Björn; Keum, Chang-Min; Kasemann, Daniel; Naab, Ben; Bao, Zhenan; Leo, Karl

    2016-11-23

    Organic field-effect transistors hold the promise of enabling low-cost and flexible electronics. Following its success in organic optoelectronics, the organic doping technology is also used increasingly in organic field-effect transistors. Doping not only increases device performance, but it also provides a way to fine-control the transistor behavior, to develop new transistor concepts, and even improve the stability of organic transistors. This Review summarizes the latest progress made in the understanding of the doping technology and its application to organic transistors. It presents the most successful doping models and an overview of the wide variety of materials used as dopants. Further, the influence of doping on charge transport in the most relevant polycrystalline organic semiconductors is reviewed, and a concise overview on the influence of doping on transistor behavior and performance is given. In particular, recent progress in the understanding of contact doping and channel doping is summarized.

  13. Two supramolecular complexes based on polyoxometalates and Co-EDTA units via covalent connection or non-covalent interaction

    Energy Technology Data Exchange (ETDEWEB)

    Teng, Chunlin; Xiao, Hanxi [Key Laboratory of Theoretical Organic Chemistry and Functional Molecule for Ministry of Education, Hunan University of Science and Technology, Xiangtan 411201 (China); Cai, Qing [Chemistry Department, City University of New York, New York, NY 10016 (United States); Tang, Jianting; Cai, Tiejun [Key Laboratory of Theoretical Organic Chemistry and Functional Molecule for Ministry of Education, Hunan University of Science and Technology, Xiangtan 411201 (China); Deng, Qian, E-mail: dengqian10502@163.com [Key Laboratory of Theoretical Organic Chemistry and Functional Molecule for Ministry of Education, Hunan University of Science and Technology, Xiangtan 411201 (China)

    2016-11-15

    Two new 3D network organic-inorganic hybrid supramolecular complexes ([Na{sub 6}(CoEDTA){sub 2}(H{sub 2}O){sub 13}]·(H{sub 2}SiW{sub 12}O{sub 40})·xH{sub 2}O)n (1) and [CoH{sub 4}EDTA(H{sub 2}O)]{sub 2}(SiW{sub 12}O{sub 40})·15H{sub 2}O (2) (H{sub 4}EDTA=Ethylenediamine tetraacetic acid) have been successfully synthesized by solution method, and characterized by infrared spectrum (IR), thermogravimetric-differential thermal analysis (TG-DTA), cyclic voltammetry (CV) and single{sup −}crystal X-ray diffraction (XRD). Both of the complexes are the supramolecules, but with different liking mode, they are two representative models of supramolecule. complex (1) is a 3D infinite network supramolecular coordination polymer with a rare multi-metal sturcture of sodium-cobalt-containing, which is mainly linked through coordinate-covalent bonds. While complex (2) is normal supramolecule, which linked by non-covalent interactions, such as H-bonding interaction, electrostatic interaction and van der waals force. Both of complex (1) and (2) exhibit good catalytic activities for catalytic oxidation of methanol, when the initial concentration of methanol is 3.0 g m{sup −3}, flow rate is 10 mL min{sup −1}, and the quality of catalyst is 0.2 g, for complex (1) and complex (2) the maximum elimination rates of methanol are 85% (150 °C) and 92% (120 °C), respectively. - Graphical abstract: Two new organic-inorganic hybrid supramolecular complexes based on Co-EDTA, and Keggin polyanions have been successfully synthesized with different pH value by solution method. They are attributed to two representative models of supramolecule. Complex(1) is an infinite coordination polymer with a rare multi-metal sturcture of sodium-cobalt-containing, which is mainly linked through covalent bonds. Complex (2) is a normal supramolecule, which linked by non-covalent interactions of H-bonding interaction, electrostatic interaction and van der waals force. - Highlights: • Two supramolecules

  14. Building high-coverage monolayers of covalently bound magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Mackenzie G.; Teplyakov, Andrew V., E-mail: andrewt@udel.edu

    2016-12-01

    Graphical abstract: - Highlights: • A method for forming a layer of covalently bound nanoparticles is offered. • A nearly perfect monolayer of covalently bound magnetic nanoparticles was formed on gold. • Spectroscopic techniques confirmed covalent binding by the “click” reaction. • The influence of the functionalization scheme on surface coverage was investigated. - Abstract: This work presents an approach for producing a high-coverage single monolayer of magnetic nanoparticles using “click chemistry” between complementarily functionalized nanoparticles and a flat substrate. This method highlights essential aspects of the functionalization scheme for substrate surface and nanoparticles to produce exceptionally high surface coverage without sacrificing selectivity or control over the layer produced. The deposition of one single layer of magnetic particles without agglomeration, over a large area, with a nearly 100% coverage is confirmed by electron microscopy. Spectroscopic techniques, supplemented by computational predictions, are used to interrogate the chemistry of the attachment and to confirm covalent binding, rather than attachment through self-assembly or weak van der Waals bonding. Density functional theory calculations for the surface intermediate of this copper-catalyzed process provide mechanistic insight into the effects of the functionalization scheme on surface coverage. Based on this analysis, it appears that steric limitations of the intermediate structure affect nanoparticle coverage on a flat solid substrate; however, this can be overcome by designing a functionalization scheme in such a way that the copper-based intermediate is formed on the spherical nanoparticles instead. This observation can be carried over to other approaches for creating highly controlled single- or multilayered nanostructures of a wide range of materials to result in high coverage and possibly, conformal filling.

  15. Dislocations in materials with mixed covalent and metallic bonding

    International Nuclear Information System (INIS)

    Nguyen-Manh, D.; Cawkwell, M.J.; Groeger, R.; Mrovec, M.; Porizek, R.; Pettifor, D.G.; Vitek, V.

    2005-01-01

    Environment-dependent bond-order potentials have been developed for L1 0 TiAl, bcc Mo and fcc Ir. They comprise both the angular character of bonding and the screening effect of nearly free electrons. These potentials have been employed in atomistic studies of screw dislocations that revealed the non-planar character of their cores. It is argued that both covalent as well as metallic character of bonding govern these structures, which in turn control the mechanical behaviour

  16. Preparation and characterization of two types of covalently immobilized amyloglucosidase

    Directory of Open Access Journals (Sweden)

    ZORAN VUJCIC

    2005-05-01

    Full Text Available Amyloglucosidase from A. niger was covalently immobilized onto poly (GMA-co-EGDMA by the glutaraldehyde and periodate method. The immobilization of amyloglucosidase after periodate oxidation gave a preparate with the highest specific activity reported so far on similar polymers. The obtained immobilized preparates show the same pH optimum, but a higher temperature optimum compared with the soluble enzyme. The kinetic parameters for the hydrolysis of soluble starch by free and both immobilized enzymes were determined.

  17. The protein inhibitor of nNOS (PIN/DLC1/LC8) binding does not inhibit the NADPH-dependent heme reduction in nNOS, a key step in NO synthesis.

    Science.gov (United States)

    Parhad, Swapnil S; Jaiswal, Deepa; Ray, Krishanu; Mazumdar, Shyamalava

    2016-03-25

    The neuronal nitric oxide synthase (nNOS) is an essential enzyme involved in the synthesis of nitric oxide (NO), a potent neurotransmitter. Although previous studies have indicated that the dynein light chain 1 (DLC1) binding to nNOS could inhibit the NO synthesis, the claim is challenged by contradicting reports. Thus, the mechanism of nNOS regulation remained unclear. nNOS has a heme-bearing, Cytochrome P450 core, and the functional enzyme is a dimer. The electron flow from NADPH to Flavin, and finally to the heme of the paired nNOS subunit within a dimer, is facilitated upon calmodulin (CaM) binding. Here, we show that DLC1 binding to nNOS-CaM complex does not affect the electron transport from the reductase to the oxygenase domain. Therefore, it cannot inhibit the rate of NADPH-dependent heme reduction in nNOS, which results in l-Arginine oxidation. Also, the NO release activity does not decrease with increasing DLC1 concentration in the reaction mix, which further confirmed that DLC1 does not inhibit nNOS activity. These findings suggest that the DLC1 binding may have other implications for the nNOS function in the cell. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Evidence of significant covalent bonding in Au(CN)(2)(-).

    Science.gov (United States)

    Wang, Xue-Bin; Wang, Yi-Lei; Yang, Jie; Xing, Xiao-Peng; Li, Jun; Wang, Lai-Sheng

    2009-11-18

    The Au(CN)(2)(-) ion is the most stable Au compound known for centuries, yet a detailed understanding of its chemical bonding is still lacking. Here we report direct experimental evidence of significant covalent bonding character in the Au-C bonds in Au(CN)(2)(-) using photoelectron spectroscopy and comparisons with its lighter congeners, Ag(CN)(2)(-) and Cu(CN)(2)(-). Vibrational progressions in the Au-C stretching mode were observed for all detachment transitions for Au(CN)(2)(-), in contrast to the atomic-like transitions for Cu(CN)(2)(-), revealing the Au-C covalent bonding character. In addition, rich electronic structural information was obtained for Au(CN)(2)(-) by employing 118 nm detachment photons. Density functional theory and high-level ab initio calculations were carried out to understand the photoelectron spectra and obtain insight into the nature of the chemical bonding in the M(CN)(2)(-) complexes. Significant covalent character in the Au-C bonding due to the strong relativistic effects was revealed in Au(CN)(2)(-), consistent with its high stability.

  19. Covalently bound molecular states in beryllium and carbon isotopes

    International Nuclear Information System (INIS)

    Wolfram von, Oertzen; Hans-Gerhard, Bohlen; Wolfram von, Oertzen

    2003-01-01

    Nuclear clustering in N=Z nuclei has been studied since many decades. States close to the decay thresholds, as described by the Ikeda diagram, are of particular interest. Recent studies in loosely bound systems, as observed with neutron-rich nuclei has revived the interest in cluster structures in nuclei, with additional valence neutrons, which give rise to pronounced covalent molecular structures. The Beryllium isotopes represent the first example of such unique states in nuclear physics with extreme deformations. In the deformed shell model these are referred to as super- and hyper-deformation. These states can be described explicitly by molecular concepts, with neutrons in covalent binding orbits. Examples of recent experiments performed at the HMI-Berlin demonstrating the molecular structure of the rotational bands in Beryllium isotopes are presented. Further work on chain states (nuclear polymers) in the carbon isotopes is in progress, these are the first examples of deformed structures in nuclei with an axis ratio of 3:1. A threshold diagram with clusters bound via neutrons in covalent molecular configurations can be established, which can serve as a guideline for future work. (authors)

  20. TiO2-NT electrodes modified with Ag and diamond like carbon (DLC) for hydrogen production by alkaline water electrolysis

    Science.gov (United States)

    Baran, Evrim; Baz, Zeynep; Esen, Ramazan; Yazici Devrim, Birgül

    2017-10-01

    In present work, the two-step anodization technique was applied for synthesis of TiO2 nanotube (NT). Silver and diamond like carbon (DLC) were coated on the surface of as prepared TiO2-NT using chemical reduction method and MW ECR plasma system. The morphology, composition and structure of the electrodes were examined by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The results showed that Ag nanoparticles, having size in the range of 48-115 nm, are evenly distributed on the top, inside and outside surface of TiO2-NT and when DLC was coated on the surface of TiO2-NT and TiO2-NT-Ag, the top of nanotubes were partially open and the pore diameter of hexagonal structure decreased from 165 nm to of 38-80 nm. On the other hand, the microhardness test and contact angle measurements revealed that additions of Ag and diamond like carbon have a positive effect on the mechanical properties of TiO2-NT film. The electrocatalytic properties of the electrodes towards the hydrogen evolution reaction (HER) were investigated by the electrochemical measurements recorded in 1 M KOH solution. In addition, long-term durability of electrodes towards HER and the energy consumption of alkaline electrolysis were investigated. The energy requirement showed that while the deposition of silver provides approximately 14.95% savings of the energy consumption, the DLC coating causes increase in energy consumption.

  1. Unravelling the interplay of geometrical, magnetic and electronic properties of metal-doped graphene nanomeshes

    KAUST Repository

    Fadlallah, Mohamed M.

    2016-12-02

    Graphene nanomeshes (GNMs), formed by creating a superlattice of pores in graphene, possess rich physical and chemical properties. Many of these properties are determined by the pore geometry. In this work, we use first principles calculations to study the magnetic and electronic properties of metal-doped nitrogen-passivated GNMs. We find that the magnetic behaviour is dependent on the pore shape (trigonal versus hexagonal) as dictated by the number of covalent bonds formed between the 3d metal and the passivating N atoms. We also find that Cr and V doped trigonal-pore GNMs, and Ti doped GNMs are the most favourable for spintronic applications. The calculated magnetic properties of Fe-doped GNMs compare well with recent experimental observations. The studied systems are useful as spin filters and chemical sensors.

  2. Effect of pressure and doping on lattice structure of zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Zolfaghari, Mahmoud, E-mail: mzolfaghari@phys.usb.ac.ir

    2017-01-15

    The semiconductor ZnO belongs to the IIb-VI binary compound. It has a high exciton binding energy of 60 meV. The bonding in these materials is covalent with some ionic character. Induced changes on the physical properties of Mn doped ZnO samples due to different dopant concentrations and pressure were evaluated. The results obtained showed higher solubility limit for Mn doped ZnO due to pressure. The trend of XRD results for higher Mn concentration (9 at%) as pressure increases, was towards doping improvement. The XRD, SEM and UV–vis study of the samples also revealed that there were variations in the lattice parameters, nanoparticle size and bandgap energy of the doped and pressurized doped samples. Further, the directions of variation of bandgap energy values and calculated particle size, as well as SEM values of the doped samples due to pressure variation were found to be the same i.e. all of them together either increase or decrease as pressure varies. However, these variations were found to be opposite to that of lattice constants (all a and most c values) variation for both Mn dopant concentrations (3 at% and 9 at%). These physical variations of unpressurized doped samples can be attributed to the change in the polar bonding of the elemental constitutions in the lattice. While for the pressurized doped samples, the variations attributed to repulsion of lone pairs as well as change in the electronegativity of the system.

  3. Covalent bonding and J-J mixing effects on the EPR parameters of Er3+ions in GaN crystal

    Institute of Scientific and Technical Information of China (English)

    柴瑞鹏; 李隆; 梁良; 庞庆

    2016-01-01

    The EPR parameters of trivalent Er3+ ions doped in hexagonal GaN crystal have been studied by diagonalizing the 364×364 complete energy matrices. The results indicate that the resonance ground states may be derived from the Kramers doubletΓ6. The EPR g-factors may be ascribed to the stronger covalent bonding and nephelauxetic effects compared with other rare-earth doped complexes, as a result of the mismatch of ionic radii of the impurity Er3+ion and the replaced Ga3+ion apart from the intrinsic covalency of host GaN. Furthermore, the J–J mixing effects on the EPR parameters from the high-lying manifolds have been evaluated. It is found that the dominant J–J mixing contribution is from the manifold 2K15/2, which accounts for about 2.5%. The next important J–J contribution arises from the crystal–field mixture between the ground state 4I15/2 and the first excited state 4I13/2, and is usually less than 0.2%. The contributions from the rest states may be ignored.

  4. First principle investigations on Boron doped Fe2VAl Heusler alloy

    International Nuclear Information System (INIS)

    Venkatesh, Ch.; Srivastava, S.K.; Rao, V.V.

    2014-01-01

    The role of atomic size of sp-element is investigated through theoretical calculations and basic experiments to understand the physical properties of Boron doped Fe 2 VAl alloy. The results of ab-initio calculations on ordered L2 1 structure of Fe 2 VAl 1-x B x (x=0, 0.5, 1) alloys have been compared to understand the role of sp-element size on the hybridization among their respective valance states. Interestingly, semi-metallic and paramagnetic like ground states were found in the Boron doped alloys in similar to Fe 2 VAl, eliminating the role of size of the doppent sp-atom. These calculations result in hybridization where the covalent distribution of valance states among the atoms is responsible to produce a finite pseudo-gap at the Fermi level. The observed features could be explained on the basis of covalent theory of magnetism in which an amount of spectral weight transfer occurs in the DOS spectrum among the same spin orbitals, leading to symmetric distribution of bonding and anti-bonding states. However, the obtained experimental findings on Boron doped alloys are in contrast with these calculations, indicating that experimentally the alloy formation into an ideal L2 1 lattice does not happen while doping with Boron. Further, the micro structural analysis shows Boron segregation across the grain boundaries that may form magnetic inhomogeneities in the lattice of Boron doped Fe 2 VAl alloys which preferably cause these experimental anomalies

  5. Covalent DNA-protein crosslinking occurs after hyperthermia and radiation

    International Nuclear Information System (INIS)

    Cress, A.E.; Bowden, G.T.

    1983-01-01

    Covalent DNA-protein crosslinks occur in exponentially growing mouse leukemia cells (L1210) after exposure to ionizing radiation. The amount of DNA-protein crosslinks as measured by a filter binding assay is dose dependent upon X irradiation. Although hyperthermia and radiation in combination are synergistic with respect to cell lethality, the combination does not result in an increase of DNA-protein crosslinks when assayed immediately following treatments. Hyperthermia (43 degrees C/15 min) given prior to radiation does not alter the radiation dose dependency of the amount of initial crosslinking. In addition, the amount of DNA-protein crosslinking produced by heat plus radiation is independent of the length of heating the cells at 43 degrees C. The DNA-protein crosslinks produced by 50-Gy X ray alone are removed after 2 hr at 37 degrees C. However, if hyperthermia (43 degrees C/15 min) is given prior to 100-Gy X ray, the removal of DNA-protein crosslinks is delayed until 4.0 hr after radiation. Phospho-serine and phospho-threonine bonds are not produced with either radiation or the combination of hyperthermia plus radiation as judged by the resistance of the bonds to guanidine hydrochloride. However, hyperthermia plus radiation causes an increase in phosphate to nitrogen type bonding. These results show that radiation alone causes covalent DNA-protein crosslinks. Hyperthermia in combination with radiation does not increase the total amount of the crosslinks but delays the removal of the crosslinks and alters the distribution of the types of chemical bonding. These data suggest that the synergistic action on hyperthermia with radiation is more related to the rate of removal and the type of chemical bonding involved in the covalent DNA-protein crosslinks rather than the amount of DNA-protein crosslinks

  6. Macromolecular weight specificity in covalent binding of bromobenzene

    International Nuclear Information System (INIS)

    Sun, J.D.; Dent, J.G.

    1984-01-01

    Bromobenzene is a hepatotoxicant that causes centrilobular necrosis. Pretreatment of animals with 3-methylcholanthrene decreases and phenobarbital pretreatment enhances the hepatotoxic action of this compound. We have investigated the macromolecular weight specificity of the covalent interactions of bromobenzene with liver macromolecules following incubation of [ 14 C]bromobenzene in isolated hepatocytes. Hepatocytes were prepared from Fischer-344 rats treated for 3 days with 3-methylcholanthrene, phenobarbital, or normal saline. After a 1-hr incubation, total covalent binding, as measured by sodium dodecyl sulfate-equilibrium dialysis, was twofold less in hepatocytes from 3-methylcholanthrene-treated rats and sixfold greater in hepatocytes from phenobarbital-treated rats, as compared to hepatocytes from control animals. Analysis of the arylated macromolecules by electrophoresis on 15% sodium dodecyl sulfate-polyacrylamide disc gels indicated that in the first 1 to 3 min of incubation substantial amounts of covalently bound radiolabel were associated with macromolecules of between 20,000 and 40,000. The amount of radioactivity associated with these macromolecules rapidly diminished in hepatocytes from control and 3-methylcholanthrene-treated animals. In hepatocytes from phenobarbital-treated animals, the amount of radioactivity associated with macromolecules, 20,000, increased throughout the incubation. The amount of radiolabel associated with macromolecules, 20,000, increased in all incubations. When nontoxic doses of phenylmethylsulfonyl fluoride, a specific inhibitor of serine proteases, were added to control hepatocytes incubated with [ 14 C]-bromobenzene, the decrease in radioactivity associated with larger (greater than 20,000) macromolecules was inhibited and a corresponding lack of increase in radioactivity associated with smaller macromolecules was observed

  7. The Effect of Bias Voltage and Gas Pressure on the Structure, Adhesion and Wear Behavior of Diamond Like Carbon (DLC Coatings With Si Interlayers

    Directory of Open Access Journals (Sweden)

    Liam Ward

    2014-04-01

    Full Text Available In this study diamond like carbon (DLC coatings with Si interlayers were deposited on 316L stainless steel with varying gas pressure and substrate bias voltage using plasma enhanced chemical vapor deposition (PECVD technology. Coating and interlayer thickness values were determined using X-ray photoelectron spectroscopy (XPS which also revealed the presence of a gradient layer at the coating substrate interface. Coatings were evaluated in terms of the hardness, elastic modulus, wear behavior and adhesion. Deposition rate generally increased with increasing bias voltage and increasing gas pressure. At low working gas pressures, hardness and modulus of elasticity increased with increasing bias voltage. Reduced hardness and modulus of elasticity were observed at higher gas pressures. Increased adhesion was generally observed at lower bias voltages and higher gas pressures. All DLC coatings significantly improved the overall wear resistance of the base material. Lower wear rates were observed for coatings deposited with lower bias voltages. For coatings that showed wear tracks considerably deeper than the coating thickness but without spallation, the wear behavior was largely attributed to deformation of both the coating and substrate with some cracks at the wear track edges. This suggests that coatings deposited under certain conditions can exhibit ultra high flexible properties.

  8. Effect of photocurrent enhancement in porphyrin–graphene covalent hybrids

    International Nuclear Information System (INIS)

    Tang, Jianguo; Niu, Lin; Liu, Jixian; Wang, Yao; Huang, Zhen; Xie, Shiqiang; Huang, Linjun; Xu, Qingsong; Wang, Yuan; Belfiore, Laurence A.

    2014-01-01

    Graphene oxide (GO) sheets were covalently functionalized with 5-p-aminophenyl-10,15,20-triphenylporphyrin (NH 2 TPP) by an amidation reaction between the amino group in NH 2 TPP and carboxyl groups in GO. The Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning and transmission electron microscopies reveal that NH 2 TPP covalent bonds form on the double surface of graphene oxide sheets, generating a unique nano-framework, i.e., NH 2 TPP-graphene-NH 2 TPP. Its UV–visible spectroscopy reveals that the absorption spectrum is not a linear superposition of the spectra of NH 2 TPP and graphene oxide, because a 59 nm red shift of the strong graphene oxide absorption is observed from 238 to 297 nm, with significant spectral broadening between 300 and 700 nm. Fluorescence emission spectroscopy indicates efficient quenching of NH 2 TPP photoluminescence in this hybrid material, suggesting that photo-induced electron transfer occurs at the interface between NH 2 TPP and GO. A reversible on/off photo-current density of 47 mA/cm 2 is observed when NH 2 TPP-graphene-NH 2 TPP hybrid sandwiches are subjected to pulsed white-light illumination. Covalently-bound porphyrins decrease the optical HOMO/LUMO band gap of graphene oxide by ≈ 1 eV, according to UV–visible spectroscopy. Cyclic voltammetry predicts a small HOMO/LUMO band gap of 0.84 eV for NH 2 TPP-graphene-NH 2 TPP hybrid sandwiches, which is consistent with efficient electron transfer and fluorescence quenching. - Highlights: • Porphyrins are covalently bound to sheets of graphene oxide via an amidation reaction. • The formed hetero-junction interface decreases the optical band gap of graphene oxide. • Cyclic voltammetry predicts a graphene oxide band gap of 0.84 eV, which is easily photo-excited. • Its on/off photo-current density of 46 μA/cm 2 is 5-fold larger than that for physically stacked hybrid

  9. The Search for Covalently Ligandable Proteins in Biological Systems

    Directory of Open Access Journals (Sweden)

    Syed Lal Badshah

    2016-09-01

    Full Text Available This commentary highlights the recent article published in Nature, June 2016, titled: “Proteome-wide covalent ligand discovery in native biological systems”. They screened the whole proteome of different human cell lines and cell lysates. Around 700 druggable cysteines in the whole proteome were found to bind the electrophilic fragments in both active and inactive states of the proteins. Their experiment and computational docking results agreed with one another. The usefulness of this study in terms of bringing a change in medicinal chemistry is highlighted here.

  10. Covalent functionalization of carbon nanotubes with tetramanganese complexes

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  11. Reaction mechanisms for on-surface synthesis of covalent nanostructures

    International Nuclear Information System (INIS)

    Björk, J

    2016-01-01

    In recent years, on-surface synthesis has become an increasingly popular strategy to form covalent nanostructures. The approach has great prospects for facilitating the manufacture of a range of fascinating materials with atomic precision. However, the on-surface reactions are enigmatic to control, currently restricting its bright perspectives and there is a great need to explore how the reactions are governed. The objective of this topical review is to summarize theoretical work that has focused on comprehending on-surface synthesis protocols through studies of reaction mechanisms. (topical review)

  12. Product Purchases by DLC

    Data.gov (United States)

    Montgomery County of Maryland — This dataset contains a list of items in case units by category and supplier that have been purchased by the Department of Liquor Control in the past month. Update...

  13. Doping control in sport

    DEFF Research Database (Denmark)

    Overbye, Marie Birch

    2016-01-01

    Doping testing is a key component enforced by anti-doping authorities to detect and deter doping in sport. Policy is developed to protect athletes' right to participate in doping-free sport; and testing is a key tool to secure this right. Accordingly, athletes' responses to anti-doping efforts...... are important. This article explores how the International Standards for Testing, which face different interpretations and challenges when policy is implemented, are perceived by elite athletes. Particularly, this article aims to investigate how elite athletes perceive the functioning of the testing system (i.......e., the efforts of stakeholders involved in testing) in their own sport both nationally and worldwide. Moreover, it seeks to identify whether specific factors such as previous experience of testing and perceived proximity of doping have an impact on athletes' perceptions of the testing system. The study comprises...

  14. The Anti-Doping Movement.

    Science.gov (United States)

    Willick, Stuart E; Miller, Geoffrey D; Eichner, Daniel

    2016-03-01

    Historical reports of doping in sports date as far back as the ancient Greek Olympic Games. The anti-doping community considers doping in sports to be cheating and a violation of the spirit of sport. During the past century, there has been an increasing awareness of the extent of doping in sports and the health risks of doping. In response, the anti-doping movement has endeavored to educate athletes and others about the health risks of doping and promote a level playing field. Doping control is now undertaken in most countries around the world and at most elite sports competitions. As athletes have found new ways to dope, however, the anti-doping community has endeavored to strengthen its educational and deterrence efforts. It is incumbent upon sports medicine professionals to understand the health risks of doping and all doping control processes. Copyright © 2016 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

  15. Covalent Organic Frameworks: From Materials Design to Biomedical Application

    Directory of Open Access Journals (Sweden)

    Fuli Zhao

    2017-12-01

    Full Text Available Covalent organic frameworks (COFs are newly emerged crystalline porous polymers with well-defined skeletons and nanopores mainly consisted of light-weight elements (H, B, C, N and O linked by dynamic covalent bonds. Compared with conventional materials, COFs possess some unique and attractive features, such as large surface area, pre-designable pore geometry, excellent crystallinity, inherent adaptability and high flexibility in structural and functional design, thus exhibiting great potential for various applications. Especially, their large surface area and tunable porosity and π conjugation with unique photoelectric properties will enable COFs to serve as a promising platform for drug delivery, bioimaging, biosensing and theranostic applications. In this review, we trace the evolution of COFs in terms of linkages and highlight the important issues on synthetic method, structural design, morphological control and functionalization. And then we summarize the recent advances of COFs in the biomedical and pharmaceutical sectors and conclude with a discussion of the challenges and opportunities of COFs for biomedical purposes. Although currently still at its infancy stage, COFs as an innovative source have paved a new way to meet future challenges in human healthcare and disease theranostic.

  16. From covalent bonding to coalescence of metallic nanorods

    Directory of Open Access Journals (Sweden)

    Lee Soohwan

    2011-01-01

    Full Text Available Abstract Growth of metallic nanorods by physical vapor deposition is a common practice, and the origin of their dimensions is a characteristic length scale that depends on the three-dimensional Ehrlich-Schwoebel (3D ES barrier. For most metals, the 3D ES barrier is large so the characteristic length scale is on the order of 200 nm. Using density functional theory-based ab initio calculations, this paper reports that the 3D ES barrier of Al is small, making it infeasible to grow Al nanorods. By analyzing electron density distributions, this paper shows that the small barrier is the result of covalent bonding in Al. Beyond the infeasibility of growing Al nanorods by physical vapor deposition, the results of this paper suggest a new mechanism of controlling the 3D ES barrier and thereby nanorod growth. The modification of local degree of covalent bonding, for example, via the introduction of surfactants, can increase the 3D ES barrier and promote nanorod growth, or decrease the 3D ES barrier and promote thin film growth.

  17. Non-covalent and reversible functionalization of carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Antonello Di Crescenzo

    2014-09-01

    Full Text Available Carbon nanotubes (CNTs have been proposed and actively explored as multipurpose innovative nanoscaffolds for applications in fields such as material science, drug delivery and diagnostic applications. Their versatile physicochemical features are nonetheless limited by their scarce solubilization in both aqueous and organic solvents. In order to overcome this drawback CNTs can be easily non-covalently functionalized with different dispersants. In the present review we focus on the peculiar hydrophobic character of pristine CNTs that prevent them to easily disperse in organic solvents. We report some interesting examples of CNTs dispersants with the aim to highlight the essential features a molecule should possess in order to act as a good carbon nanotube dispersant both in water and in organic solvents. The review pinpoints also a few examples of dispersant design. The last section is devoted to the exploitation of the major quality of non-covalent functionalization that is its reversibility and the possibility to obtain stimuli-responsive precipitation or dispersion of CNTs.

  18. Bifunctional avidin with covalently modifiable ligand binding site.

    Directory of Open Access Journals (Sweden)

    Jenni Leppiniemi

    Full Text Available The extensive use of avidin and streptavidin in life sciences originates from the extraordinary tight biotin-binding affinity of these tetrameric proteins. Numerous studies have been performed to modify the biotin-binding affinity of (streptavidin to improve the existing applications. Even so, (streptavidin greatly favours its natural ligand, biotin. Here we engineered the biotin-binding pocket of avidin with a single point mutation S16C and thus introduced a chemically active thiol group, which could be covalently coupled with thiol-reactive molecules. This approach was applied to the previously reported bivalent dual chain avidin by modifying one binding site while preserving the other one intact. Maleimide was then coupled to the modified binding site resulting in a decrease in biotin affinity. Furthermore, we showed that this thiol could be covalently coupled to other maleimide derivatives, for instance fluorescent labels, allowing intratetrameric FRET. The bifunctional avidins described here provide improved and novel tools for applications such as the biofunctionalization of surfaces.

  19. Privileged Electrophile Sensors: A Resource for Covalent Drug Development.

    Science.gov (United States)

    Long, Marcus John Curtis; Aye, Yimon

    2017-07-20

    This Perspective delineates how redox signaling affects the activity of specific enzyme isoforms and how this property may be harnessed for rational drug design. Covalent drugs have resurged in recent years and several reports have extolled the general virtues of developing irreversible inhibitors. Indeed, many modern pharmaceuticals contain electrophilic appendages. Several invoke a warhead that hijacks active-site nucleophiles whereas others take advantage of spectator nucleophilic side chains that do not participate in enzymatic chemistry, but are poised to bind/react with electrophiles. The latest data suggest that innate electrophile sensing-which enables rapid reaction with an endogenous signaling electrophile-is a quintessential resource for the development of covalent drugs. For instance, based on recent work documenting isoform-specific electrophile sensing, isozyme non-specific drugs may be converted to isozyme-specific analogs by hijacking privileged first-responder electrophile-sensing cysteines. Because this approach targets functionally relevant cysteines, we can simultaneously harness previously untapped moonlighting roles of enzymes linked to redox sensing. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Solvent-free covalent functionalization of nanodiamond with amines

    International Nuclear Information System (INIS)

    Basiuk, Elena V.; Santamaría-Bonfil, Adriana; Meza-Laguna, Victor; Gromovoy, Taras Yu.; Alvares-Zauco, Edgar; Contreras-Torres, Flavio F.; Rizo, Juan; Zavala, Guadalupe; Basiuk, Vladimir A.

    2013-01-01

    Covalent functionalization of pristine nanodiamond (ND) with 1,12-diaminododecane (DAD), 1,5-diaminonaphthalene (DAN), poly(ethylene glycol) diamine (PEGDA), and polyethylenimine (PEI) was carried out by employing solvent-free methodology, which is based on thermal instead of chemical activation of carboxylic groups at ND surface. A simple solubility/dispersibility test in water and isopropanol showed an increased lipophilicity of the functionalized samples. The conversion of intrinsic carboxylic groups into the corresponding amide derivatives was characterized by means of Fourier-transform infrared spectroscopy. Thermogravimetric analysis found the highest organic content of about 18% for ND-PEI, followed by ND-DAD, for which the contribution of covalently bonded diamine was estimated to be of ca. 10%. In temperature programmed desorption measurements with mass spectrometric detection, the presence of organic functionalizing groups changed both mass spectra and thermodesorption curves of ND. The changes in morphology of primary and secondary ND aggregates were characterized by scanning and transmission electron microscopy, as well as by atomic force microscopy. The current–voltage measurements under atmospheric pressure found an increased conductivity for ND-DAN, as compared to that of pristine ND, whereas for ND-DAD, ND-PEGDA and ND-PEI a dramatic decrease in conductivity due to functionalization was observed.

  1. Solvent-free covalent functionalization of nanodiamond with amines

    Energy Technology Data Exchange (ETDEWEB)

    Basiuk, Elena V., E-mail: elenagd@unam.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510 México D.F. (Mexico); Santamaría-Bonfil, Adriana; Meza-Laguna, Victor [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510 México D.F. (Mexico); Gromovoy, Taras Yu. [Institute of Surface Chemistry, National Academy of Sciences of the Ukraine, Gen. Naumova 17, 03164 Kiev (Ukraine); Alvares-Zauco, Edgar [Facultad de Ciencias, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510 México D.F. (Mexico); Contreras-Torres, Flavio F.; Rizo, Juan [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510 México D.F. (Mexico); Zavala, Guadalupe [Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, 62210, Cuernavaca, Morelos (Mexico); Basiuk, Vladimir A. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510 México, D.F. (Mexico)

    2013-06-15

    Covalent functionalization of pristine nanodiamond (ND) with 1,12-diaminododecane (DAD), 1,5-diaminonaphthalene (DAN), poly(ethylene glycol) diamine (PEGDA), and polyethylenimine (PEI) was carried out by employing solvent-free methodology, which is based on thermal instead of chemical activation of carboxylic groups at ND surface. A simple solubility/dispersibility test in water and isopropanol showed an increased lipophilicity of the functionalized samples. The conversion of intrinsic carboxylic groups into the corresponding amide derivatives was characterized by means of Fourier-transform infrared spectroscopy. Thermogravimetric analysis found the highest organic content of about 18% for ND-PEI, followed by ND-DAD, for which the contribution of covalently bonded diamine was estimated to be of ca. 10%. In temperature programmed desorption measurements with mass spectrometric detection, the presence of organic functionalizing groups changed both mass spectra and thermodesorption curves of ND. The changes in morphology of primary and secondary ND aggregates were characterized by scanning and transmission electron microscopy, as well as by atomic force microscopy. The current–voltage measurements under atmospheric pressure found an increased conductivity for ND-DAN, as compared to that of pristine ND, whereas for ND-DAD, ND-PEGDA and ND-PEI a dramatic decrease in conductivity due to functionalization was observed.

  2. Versatile and Tunable Transparent Conducting Electrodes Based on Doped Graphene

    KAUST Repository

    Mansour, Ahmed E.

    2016-11-25

    The continued growth of the optoelectronics industry and the emergence of wearable and flexible electronics will continue to place an ever increasing pressure on replacing ITO, the most widely used transparent conducting electrode (TCE). Among the various candidates, graphene shows the highest optical transmittance in addition to promising electrical transport properties. The currently available large-scale synthesis routes of graphene result in polycrystalline samples rife with grain boundaries and other defects which limit its transport properties. Chemical doping of graphene is a viable route towards increasing its conductivity and tuning its work function. However, dopants are typically present at the surface of the graphene sheet, making them highly susceptible to degradation in environmental conditions. Few-layers graphene (FLG) is a more resilient form of graphene exhibiting higher conductivity and performance stability under stretching and bending as contrasted to single-layer graphene. In addition FLG presents the advantage of being amenable bulk doping by intercalation. Herein, we explore non-covalent doping routes of CVD FLG, such as surface doping, intercalation and combination thereof, through in-depth and systematic characterization of the electrical transport properties and energy levels shifts. The intercalation of FLG with Br2 and FeCl3 is demonstrated, showing the highest improvements of the figure of merit of TCEs of any doping scheme, which results from up to a five-fold increase in conductivity while maintaining the transmittance within 3% of that for the pristine value. Importantly the intercalation yields TCEs that are air-stable, due to encapsulation of the intercalant in the bulk of FLG. Surface doping with novel solution-processed metal-organic molecular species (n- and p-type) is demonstrated with an unprecedented range of work function modulation, resulting from electron transfer and the formation of molecular surface dipoles. However

  3. Infrared absorption spectra of various doping states in cuprate superconductors

    International Nuclear Information System (INIS)

    Yonemitsu, K.; Bishop, A.R.; Lorenzana, J.

    1992-01-01

    Doping states in a two-dimensional three-band extended Peierls-Hubbard model was investigated within inhomogeneous Hartree-Fock and random phase approximation. They are very sensitive to small changes of interaction parameters and their distinct vibrational and optical absorption spectra can be used to identify different doping states. For electronic parameters relevant to cuprate superconductors, as intersite electron-phonon interaction strength increases, the doping state changes from a Zhang-Rice state to a covalent molecular singlet state accompanied by local quenching of the Cu magnetic moment and large local lattice distortion in an otherwise undistorted antiferromagnetic background. In a region where both intersite electron-phonon interaction and on-site electron-electron repulsion are large, we obtain new stable global phases including a bond-order-wave state and a mixed state of spin-Peierls bonds and antiferromagnetic Cu spins, as well as many metastable states. Doping in the bond-order-wave region induces separation of spin and charge. 9 refs

  4. Thermoelectric properties of doped BaHfO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Dixit, Chandra Kr., E-mail: ckparadise@gmail.com, E-mail: sharmarameshfgiet@gmail.com [Dept. of Physics, Dr. Shakuntala Misra National Rehabilitation University, Lucknow-229001, U.P India (India); Bhamu, K. C. [Department of Physics, Goa University, Goa-403 206 (India); Sharma, Ramesh, E-mail: ckparadise@gmail.com, E-mail: sharmarameshfgiet@gmail.com [Dept. of Physics, Feroze Gandhi Institute of Engineering & Technology, Raebareli-229001, U.P India (India)

    2016-05-06

    We have studied the structural stability, electronic structure, optical properties and thermoelectric properties of doped BaHfO{sub 3} by full potential linearized augmented plane wave (FP-LAPW) method. The electronic structure of BaHfO{sub 3} doped with Sr shows enhances the indirect band gaps of 3.53 eV, 3.58 eV. The charge density plots show strong ionic bonding in Ba-Hf, and ionic and covalent bonding between Hf and O. Calculations of the optical spectra, viz., the dielectric function, refractive index and extinction coefficient are performed for the energy range are calculated and analyzed. Thermoelectric properties of semi conducting are also reported first time. The doped BaHfO{sub 3} is approximately wide band gap semiconductor with the large p-type Seebeck coefficient. The power factor of BaHfO{sub 3} is increased with Sr doping, decreases because of low electrical resistivity and thermal conductivity.

  5. Metal-doped diamond-like carbon films synthesized by filter-arc deposition

    International Nuclear Information System (INIS)

    Weng, K.-W.; Chen, Y.-C.; Lin, T.-N.; Wang, D.-Y.

    2006-01-01

    Diamond-like carbon (DLC) thin films are extensively utilized in the semiconductor, electric and cutting machine industries owing to their high hardness, high elastic modulus, low friction coefficients and high chemical stability. DLC films are prepared by ion beam-assisted deposition (BAD), sputter deposition, plasma-enhanced chemical vapor deposition (PECVD), cathodic arc evaporation (CAE), and filter arc deposition (FAD). The major drawbacks of these methods are the degraded hardness associated with the low sp 3 /sp 2 bonding ratio, the rough surface and poor adhesion caused by the presence of particles. In this study, a self-developed filter arc deposition (FAD) system was employed to prepare metal-containing DLC films with a low particle density. The relationships between the DLC film properties, such as film structure, surface morphology and mechanical behavior, with variation of substrate bias and target current, are examined. Experimental results demonstrate that FAD-DLC films have a lower ratio, suggesting that FAD-DLC films have a greater sp 3 bonding than the CAE-DLC films. FAD-DLC films also exhibit a low friction coefficient of 0.14 and half of the number of surface particles as in the CAE-DLC films. Introducing a CrN interfacial layer between the substrate and the DLC films enables the magnetic field strength of the filter to be controlled to improve the adhesion and effectively eliminate the contaminating particles. Accordingly, the FAD system improves the tribological properties of the DLC films

  6. Substitutionally doped phosphorene: electronic properties and gas sensing.

    Science.gov (United States)

    Suvansinpan, Nawat; Hussain, Fayyaz; Zhang, Gang; Chiu, Cheng Hsin; Cai, Yongqing; Zhang, Yong-Wei

    2016-02-12

    Phosphorene, a new elemental two-dimensional material, has attracted increasing attention owing to its intriguing electronic properties. In particular, pristine phospohorene, due to its ultrahigh surface-volume ratio and high chemical activity, has been shown to be promising for gas sensing (Abbas et al 2015 ACS Nano 9 5618). To further enhance its sensing ability, we perform first-principles calculations based on density functional theory to study substitutionally doped phosphorene with 17 different atoms, focusing on structures, energetics, electronic properties and gas sensing. Our calculations reveal that anionic X (X = O, C and S) dopants have a large binding energy and highly dispersive electronic states, signifying the formation of covalent X-P bonds and thus strong structural stability. Alkali atom (Li and Na) doping is found to donate most of the electrons in the outer s-orbital by forming ionic bonds with P, and the band gap decreases by pushing down the conduction band, suggesting that the optical and electronic properties of the doped phosphorene can be tailored. For doping with VIIIB-group (Fe, Co and Ni) elements, a strong affinity is predicted and the binding energy and charge transfer are correlated strongly with their electronegativity. By examining NO molecule adsorption, we find that these metal doped phosphorenes (MDPs) in general exhibit a significantly enhanced chemical activity compared with pristine phosphorene. Our study suggests that substitutionally doped phosphorene shows many intriguing electronic and optic properties different from pristine phosphorene and MDPs are promising in chemical applications involving molecular adsorption and desorption processes, such as materials growth, catalysis, gas sensing and storage.

  7. To dope or not to dope

    DEFF Research Database (Denmark)

    Overbye, Marie Birch; Knudsen, Mette Lykke; Pfister, Gertrud Ursula

    2013-01-01

    tAim: This study aims to examine the circumstances which athletes say affect their (hypothetical) consid-erations of whether to dope or not and explore the differences between athletes of different gender, ageand sport type.Methods: 645 elite athletes (mean age: 22.12; response rate: 43%) represe......tAim: This study aims to examine the circumstances which athletes say affect their (hypothetical) consid-erations of whether to dope or not and explore the differences between athletes of different gender, ageand sport type.Methods: 645 elite athletes (mean age: 22.12; response rate: 43......%) representing 40 sports completed aweb-based questionnaire. Participants were asked to imagine themselves in a situation in which theyhad to decide whether to dope or not to dope and then evaluate how different circumstances would affecttheir decisions.Results: Multiple circumstances had an effect on athletes......’ hypothetical decisions. The most effective deter-rents were related to legal and social sanctions, side-effects and moral considerations. Female athletesand younger athletes evaluated more reasons as deterrents than older, male athletes. When confrontedwith incentives to dope, the type of sport was often...

  8. Covalent Organic Framework Electrocatalysts for Clean Energy Conversion.

    Science.gov (United States)

    Lin, Chun-Yu; Zhang, Detao; Zhao, Zhenghang; Xia, Zhenhai

    2018-02-01

    Covalent organic frameworks (COFs) are promising for catalysis, sensing, gas storage, adsorption, optoelectricity, etc. owning to the unprecedented combination of large surface area, high crystallinity, tunable pore size, and unique molecular architecture. Although COFs are in their initial research stage, progress has been made in the design and synthesis of COF-based electrocatalysis for the oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, and CO 2 reduction in energy conversion and fuel generation. Design principles are also established for some of the COF materials toward rational design and rapid screening of the best electrocatalysts for a specific application. Herein, the recent advances in the design and synthesis of COF-based catalysts for clean energy conversion and storage are presented. Future research directions and perspectives are also being discussed for the development of efficient COF-based electrocatalysts. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Non-Covalent Organocatalyzed Domino Reactions Involving Oxindoles: Recent Advances

    Directory of Open Access Journals (Sweden)

    Tecla Gasperi

    2017-09-01

    Full Text Available The ubiquitous presence of spirooxindole architectures with several functionalities and stereogenic centers in bioactive molecules has been appealing for the development of novel methodologies seeking their preparation in high yields and selectivities. Expansion and refinement in the field of asymmetric organocatalysis have made possible the development of straightforward strategies that address these two requisites. In this review, we illustrate the current state-of-the-art in the field of spirooxindole synthesis through the use of non-covalent organocatalysis. We aim to provide a concise overview of very recent methods that allow to the isolation of unique, densely and diversified spirocyclic oxindole derivatives with high structural diversity via the use of cascade, tandem and domino processes.

  10. Near universal support for covalent immobilisation of enzymes for biotechnology

    International Nuclear Information System (INIS)

    Elnashar, M.M.; Millner, P.A.; Gibson, T.D.

    2005-01-01

    Carrageenan [1], natural polymer, has been modified to be used as a universal/near universal support to immobilise enzymes, where the gel remained stable at 70 degree C for 24 h at a wide range of buffers and ph s and its mechanical strength was 400% greater than the unmodified gel. The new matrix successfully immobilised covalently eight commercially used enzymes including hydrolases, Upases, oxidoreductases, proteases and dehydrogenases. It also acted as a self buffering system in case of hydrolases and stopped enzyme's product inhibition. The apparent Km values of immobilised enzymes were found in many cases to be much less than those of the free enzymes. Another interesting correlation was observed where the great lowering of the apparent Km with immobilised enzymes was directly proportional to the substrate molecular weight. In economic terms, the new matrix is at least two orders of magnitude cheaper than supports such as Eupergit C

  11. Electronic basis of hardness and phase transformations (covalent crystals)

    International Nuclear Information System (INIS)

    Gilman, J J

    2008-01-01

    Several electronic parameters measure the stabilities of covalent crystals, including minimum energy band-gap densities, inverse polarizabilities, plasma frequencies, transverse vibrational frequencies and elastic shear moduli. Convenient is the band-gap density (energy/volume; called the 'bond modulus'). For a given bonding type, the indentation hardness is proportional to the bond modulus. Examples are the group IV elements, III-V compounds; and II-VI compounds. The motion of dislocation kinks requires the excitation of bonding electrons into anti-bonding states. The bond modulus measures this together with the work done by the applied stress when a kink moves. In addition to hardness, the bond modulus measures the compressive strain (pressure) needed to transform an ambient structure into a more dense structure. Activation of such transformations also requires the excitation of bonding electrons into anti-bonding states together with the work done by the compressive stress

  12. Biofunctional paper via the covalent modification of cellulose.

    Science.gov (United States)

    Yu, Arthur; Shang, Jing; Cheng, Fang; Paik, Bradford A; Kaplan, Justin M; Andrade, Rodrigo B; Ratner, Daniel M

    2012-07-31

    Paper-based analytical devices are the subject of growing interest for the development of low-cost point-of-care diagnostics, environmental monitoring technologies, and research tools for limited-resource settings. However, there are limited chemistries available for the conjugation of biomolecules to cellulose for use in biomedical applications. Herein, divinyl sulfone (DVS) chemistry was demonstrated to immobilize small molecules, proteins, and DNA covalently onto the hydroxyl groups of cellulose membranes through nucleophilic addition. Assays on modified cellulose using protein-carbohydrate and protein-glycoprotein interactions as well as oligonucleotide hybridization showed that the membrane's bioactivity was specific, dose-dependent, and stable over a long period of time. The use of an inkjet printer to form patterns of biomolecules on DVS-activated cellulose illustrates the adaptability of the DVS functionalization technique to pattern sophisticated designs, with potential applications in cellulose-based lateral flow devices.

  13. Covalent bond orders and atomic valences from correlated wavefunctions

    Science.gov (United States)

    Ángyán, János G.; Rosta, Edina; Surján, Péter R.

    1999-01-01

    A comparison is made between two alternative definitions for covalent bond orders: one derived from the exchange part of the two-particle density matrix and the other expressed as the correlation of fluctuations (covariance) of the number of electrons between the atomic centers. Although these definitions lead to identical formulae for mono-determinantal SCF wavefunctions, they predict different bond orders for correlated wavefunctions. It is shown that, in this case, the fluctuation-based definition leads to slightly lower values of the bond order than does the exchange-based definition, provided one uses an appropriate space-partitioning technique like that of Bader's topological theory of atoms in a molecule; however, use of Mulliken partitioning in this context leads to unphysical behaviour. The example of H 2 is discussed in detail.

  14. Photoreversible Covalent Hydrogels for Soft-Matter Additive Manufacturing.

    Science.gov (United States)

    Kabb, Christopher P; O'Bryan, Christopher S; Deng, Christopher C; Angelini, Thomas E; Sumerlin, Brent S

    2018-05-16

    Reversible covalent chemistry provides access to robust materials with the ability to be degraded and reformed upon exposure to an appropriate stimulus. Photoresponsive units are attractive for this purpose, as the spatial and temporal application of light is easily controlled. Coumarin derivatives undergo a [2 + 2] cycloaddition upon exposure to long-wave UV irradiation (365 nm), and this process can be reversed using short-wave UV light (254 nm). Therefore, polymers cross-linked by coumarin groups are excellent candidates as reversible covalent gels. In this work, copolymerization of coumarin-containing monomers with the hydrophilic comonomer N, N-dimethylacrylamide yielded water-soluble, linear polymers that could be cured with long-wave UV light into free-standing hydrogels, even in the absence of a photoinitiator. Importantly, the gels were reverted back to soluble copolymers upon short-wave UV irradiation. This process could be cycled, allowing for recycling and remolding of the hydrogel into additional shapes. Further, this hydrogel can be imprinted with patterns through a mask-based, post-gelation photoetching method. Traditional limitations of this technique, such as the requirement for uniform etching in one direction, have been overcome by combining these materials with a soft-matter additive manufacturing methodology. In a representative application of this approach, we printed solid structures in which the interior coumarin-cross-linked gel is surrounded by a nondegradable gel. Upon exposure to short-wave UV irradiation, the coumarin-cross-linked gel was reverted to soluble prepolymers that were washed away to yield hollow hydrogel objects.

  15. Covalent DNA-protein crosslinking occurs after hyperthermia and radiation

    International Nuclear Information System (INIS)

    Cress, A.E.; Bowden, G.T.

    1983-01-01

    Covalent DNA-protein crosslinks occur in exponentially growing mouse leukemia cells (L1210) after exposure to ionizing radiation. The amount of DNA-protein crosslinks as measured by a filter binding assay is dose dependent upon x irradiation. Although hyperthermia and radiation in combination are synergistic with respect to cell lethality, the combination does not result in an increase of DNA-protein crosslinks when assayed immediately following treatments. Hyperthermia (43 0 C/15 min) given prior to radiation dose not alter the radiation dose dependency of the amount of initial crosslinking. In addition, the amount of DNA-protein crosslinking produced by heat plus radiation is independent of the length of heating the cells at 43 0 C. The DNA-protein crosslinks produced y 50-Gy x ray alone are removed after 2 hr at 37 0 C. However, if hyperthermia (43 0 C/15 min) is given prior to 100-Gy x ray, the removal of DNA-protein crosslinks is delayed until 4.0 hr after radiation. Phospho-serine and phospho-threonine bonds are not produced with either radiation or the combination of hyperthermia plus radiation as judged by the resistance of the bonds to guanidine hydrochloride. However, hyperthermia plus radiation causes an increase in phosphate to nitrogen type bonding. These results show that radiation alone causes covalent DNA-protein crosslinks. Hyperthermia in combination with radiation does not increase the total amount of the crosslinks but delays the removal of the crosslinks and alters the distribution of the types of chemical bonding

  16. Doped graphene supercapacitors

    Science.gov (United States)

    Ashok Kumar, Nanjundan; Baek, Jong-Beom

    2015-12-01

    Heteroatom-doped graphitic frameworks have received great attention in energy research, since doping endows graphitic structures with a wide spectrum of properties, especially critical for electrochemical supercapacitors, which tend to complement or compete with the current lithium-ion battery technology/devices. This article reviews the latest developments in the chemical modification/doping strategies of graphene and highlights the versatility of such heteroatom-doped graphitic structures. Their role as supercapacitor electrodes is discussed in detail. This review is specifically focused on the concept of material synthesis, techniques for electrode fabrication and metrics of performance, predominantly covering the last four years. Challenges and insights into the future research and perspectives on the development of novel electrode architectures for electrochemical supercapacitors based on doped graphene are also discussed.

  17. Doped graphene supercapacitors

    International Nuclear Information System (INIS)

    Kumar, Nanjundan Ashok; Baek, Jong-Beom

    2015-01-01

    Heteroatom-doped graphitic frameworks have received great attention in energy research, since doping endows graphitic structures with a wide spectrum of properties, especially critical for electrochemical supercapacitors, which tend to complement or compete with the current lithium-ion battery technology/devices. This article reviews the latest developments in the chemical modification/doping strategies of graphene and highlights the versatility of such heteroatom-doped graphitic structures. Their role as supercapacitor electrodes is discussed in detail. This review is specifically focused on the concept of material synthesis, techniques for electrode fabrication and metrics of performance, predominantly covering the last four years. Challenges and insights into the future research and perspectives on the development of novel electrode architectures for electrochemical supercapacitors based on doped graphene are also discussed. (topical review)

  18. Covalent-ionically cross-linked polyetheretherketone proton exchange membrane for direct methanol fuel cell

    CSIR Research Space (South Africa)

    Luo, H

    2010-08-01

    Full Text Available cross-linked PEEK-WC membrane, this covalent-ionically cross-linked PEEK-WC membrane exhibits extremely reduced water uptake and methanol permeability, but just slightly sacrificed proton conductivity. The proton conductivity of the covalent...

  19. Covalently bound conjugates of albumin and heparin: Synthesis, fractionation and characterization

    NARCIS (Netherlands)

    Hennink, Wim E.; Feijen, Jan; Ebert, Charles D.; Kim, Sung Wan

    1983-01-01

    Covalently bound conjugates of human serum albumin and heparin were prepared as compounds which could improve the blood-compatibility of polymer surfaces either by preadsorption or by covalent coupling of the conjugates onto blood contacting surfaces. The conjugates (10–16 weight % of heparin) were

  20. Covalently Immobilised Cytochrome C Imaged by In Situ Scanning Tunnelling Microscopy

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Olesen, Klaus G.; Danilov, Alexey I.

    1997-01-01

    In situ scanning tunnelling microscopy (STM) imaging of cytochrome c (cyt c) on polycrystalline Pt surfaces and on Au(lll) was achieved first by covalent immobilisation of 3-aminopropyltriethoxysilane (3-APTS) brought to react with oxide present on the Pt surfaces. Covalently bound 3-APTS forms...

  1. Application of the Covalent Bond Classification Method for the Teaching of Inorganic Chemistry

    Science.gov (United States)

    Green, Malcolm L. H.; Parkin, Gerard

    2014-01-01

    The Covalent Bond Classification (CBC) method provides a means to classify covalent molecules according to the number and types of bonds that surround an atom of interest. This approach is based on an elementary molecular orbital analysis of the bonding involving the central atom (M), with the various interactions being classified according to the…

  2. The role of double covalent flavin binding in chito-oligosaccharide oxidase from Fusarium graminearum

    NARCIS (Netherlands)

    Heuts, Dominic P. H. M.; Winter, Remko T.; Damsma, Gerke E.; Janssen, Dick B.; Fraaije, Marco W.

    2008-01-01

    ChitO (chito-oligosaccharide oxidase) from Fusarium graminearum catalyses the regioselective oxidation of N-acetylated oligosaccharides. The enzyme harbours an FAD cofactor that is covalently attached to His(94) and Cys(154). The functional role of this unusual bi-covalent flavin-protein linkage was

  3. Health-enhancing doping controls

    DEFF Research Database (Denmark)

    Christiansen, Ask Vest

    2010-01-01

    Editorial published at International Network of Humanistic Doping Research (INHDR) website: http://www.doping.au.dk/en/online-resources/editorials/......Editorial published at International Network of Humanistic Doping Research (INHDR) website: http://www.doping.au.dk/en/online-resources/editorials/...

  4. Dynamic Covalent Chemistry within Biphenyl Scaffolds: Reversible Covalent Bonding, Control of Selectivity, and Chirality Sensing with a Single System.

    Science.gov (United States)

    Ni, Cailing; Zha, Daijun; Ye, Hebo; Hai, Yu; Zhou, Yuntao; Anslyn, Eric V; You, Lei

    2018-01-26

    Axial chirality is a prevalent and important phenomenon in chemistry. Herein we report a combination of dynamic covalent chemistry and axial chirality for the development of a versatile platform for the binding and chirality sensing of multiple classes of mononucleophiles. An equilibrium between an open aldehyde and its cyclic hemiaminal within biphenyl derivatives enabled the dynamic incorporation of a broad range of alcohols, thiols, primary amines, and secondary amines with high efficiency. Selectivity toward different classes of nucleophiles was also achieved by regulating the distinct reactivity of the system with external stimuli. Through induced helicity as a result of central-to-axial chirality transfer, the handedness and ee values of chiral monoalcohol and monoamine analytes were reported by circular dichroism. The strategies introduced herein should find application in many contexts, including assembly, sensing, and labeling. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Origin of the high p-doping in F intercalated graphene on SiC

    KAUST Repository

    Cheng, Yingchun

    2011-08-04

    The atomic and electronic structures of F intercalated epitaxialgraphene on a SiC(0001) substrate are studied by first-principles calculations. A three-step fluorination process is proposed. First, F atoms are intercalated between the graphene and the SiC, which restores the Dirac point in the band structure. Second, saturation of the topmost Si dangling bonds introduces p-doping up to 0.37 eV. Third, F atoms bond covalently to the graphene to enhance the p-doping. Our model explains the highly p-doped state of graphene on SiC after fluorination [A. L. Walter et al., Appl. Phys. Lett. 98, 184102 (2011)].

  6. First principles study on Mn-doped LiFePO4 as cathode material for rechargeable lithium batteries

    Institute of Scientific and Technical Information of China (English)

    Fang-wei; XUE; Wei-dong; WANG; Ming-xi; SU; Rong

    2007-01-01

    The electronic structure and diffusion energy barriers of Li ions in pure and Mn-doped LiFePO4 have been studied using density functional theory (DFT). The results demonstrate clearly that Fe-O covalent bond is weaker than P-O covalent bond. Pure LiFePO4 has band gap of 0.56 eV and diffusion energy barrier of 2.57 eV for Li ions, while the dopant has small band gap of 0.25 eV and low diffusion energy barrier of 2.31 eV, which indicates that the electronic and ionic conductivity of LiFePO4 have been improved owing to doping.

  7. The effect of doping with Zn and Ni on the YBa sub 2 Cu sub 3 O sub 7 electron subsystem

    CERN Document Server

    Stolbov, S V

    1997-01-01

    The electron structure, Stoner parameters, and exchange-enhanced local contributions to the spin susceptibility have been calculated for pure, Zn-doped, and Ni-doped YBa sub 2 Cu sub 3 O sub 7 (YBCO7) within the local density approximation, using a self-consistent T-scattering matrix method. It has been found that the Zn impurity causes a breaking of p-d covalence bonds in its vicinity, and gives rise to an island of reduced spin susceptibility and density of states at the Fermi level. This leads to the destruction of spin fluctuations near the impurity. The influence of Ni doping on the YBCO7 electron subsystem is much smaller than that of Zn doping. On the basis of the present results and the spin-fluctuation model, the effects of Zn and Ni doping on the critical temperature and NMR spectra of YBCO7 have been explained. (author)

  8. Gene doping in sports.

    Science.gov (United States)

    Unal, Mehmet; Ozer Unal, Durisehvar

    2004-01-01

    Gene or cell doping is defined by the World Anti-Doping Agency (WADA) as "the non-therapeutic use of genes, genetic elements and/or cells that have the capacity to enhance athletic performance". New research in genetics and genomics will be used not only to diagnose and treat disease, but also to attempt to enhance human performance. In recent years, gene therapy has shown progress and positive results that have highlighted the potential misuse of this technology and the debate of 'gene doping'. Gene therapies developed for the treatment of diseases such as anaemia (the gene for erythropoietin), muscular dystrophy (the gene for insulin-like growth factor-1) and peripheral vascular diseases (the gene for vascular endothelial growth factor) are potential doping methods. With progress in gene technology, many other genes with this potential will be discovered. For this reason, it is important to develop timely legal regulations and to research the field of gene doping in order to develop methods of detection. To protect the health of athletes and to ensure equal competitive conditions, the International Olympic Committee, WADA and International Sports Federations have accepted performance-enhancing substances and methods as being doping, and have forbidden them. Nevertheless, the desire to win causes athletes to misuse these drugs and methods. This paper reviews the current status of gene doping and candidate performance enhancement genes, and also the use of gene therapy in sports medicine and ethics of genetic enhancement. Copyright 2004 Adis Data Information BV

  9. First-principles calculation on oxygen ion migration in alkaline-earth doped La2GeO5

    International Nuclear Information System (INIS)

    Thuy Linh, Tran Phan; Sakaue, Mamoru; Aspera, Susan Meñez; Alaydrus, Musa; Wungu, Triati Dewi Kencana; Hoang Linh, Nguyen; Kasai, Hideaki; Mohri, Takahiro; Ishihara, Tatsumi

    2014-01-01

    By using first-principles calculations based on the density functional theory, we investigated the doping effects of alkaline-earth metals (Ba, Sr and Ca) in monoclinic lanthanum germanate La 2 GeO 5 on its oxygen ion conduction. Although the lattice parameters of the doped systems changed due to the ionic radii mismatch, the crystal structures remained monoclinic. The contribution of each atomic orbital to electronic densities of states was evaluated from the partial densities of states and partial charge densities. It was confirmed that the materials behaved as ionic crystals comprising of cations of La and dopants and anions of oxygen and covalently formed GeO 4 . The doping effect on the activation barrier for oxygen hopping to the most stable oxygen vacancy site was investigated by the climbing-image nudged elastic band method. By tracing the charge density change during the hopping, it was confirmed that the oxygen motion is governed by covalent interactions. The obtained activation barriers showed excellent quantitative agreements with an experiment for the Ca- and Sr-doped systems in low temperatures as well as the qualitative trend, including the Ba-doped system. (paper)

  10. Doping of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Luessem, B.; Riede, M.; Leo, K. [Institut fuer Angewandte Photophysik, TU Dresden (Germany)

    2013-01-15

    The understanding and applications of organic semiconductors have shown remarkable progress in recent years. This material class has been developed from being a lab curiosity to the basis of first successful products as small organic LED (OLED) displays; other areas of application such as OLED lighting and organic photovoltaics are on the verge of broad commercialization. Organic semiconductors are superior to inorganic ones for low-cost and large-area optoelectronics due to their flexibility, easy deposition, and broad variety, making tailor-made materials possible. However, electrical doping of organic semiconductors, i.e. the controlled adjustment of Fermi level that has been extremely important to the success of inorganic semiconductors, is still in its infancy. This review will discuss recent work on both fundamental principles and applications of doping, focused primarily to doping of evaporated organic layers with molecular dopants. Recently, both p- and n-type molecular dopants have been developed that lead to efficient and stable doping of organic thin films. Due to doping, the conductivity of the doped layers increases several orders of magnitude and allows for quasi-Ohmic contacts between organic layers and metal electrodes. Besides reducing voltage losses, doping thus also gives design freedom in terms of transport layer thickness and electrode choice. The use of doping in applications like OLEDs and organic solar cells is highlighted in this review. Overall, controlled molecular doping can be considered as key enabling technology for many different organic device types that can lead to significant improvements in efficiencies and lifetimes. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Doping of organic semiconductors

    International Nuclear Information System (INIS)

    Luessem, B.; Riede, M.; Leo, K.

    2013-01-01

    The understanding and applications of organic semiconductors have shown remarkable progress in recent years. This material class has been developed from being a lab curiosity to the basis of first successful products as small organic LED (OLED) displays; other areas of application such as OLED lighting and organic photovoltaics are on the verge of broad commercialization. Organic semiconductors are superior to inorganic ones for low-cost and large-area optoelectronics due to their flexibility, easy deposition, and broad variety, making tailor-made materials possible. However, electrical doping of organic semiconductors, i.e. the controlled adjustment of Fermi level that has been extremely important to the success of inorganic semiconductors, is still in its infancy. This review will discuss recent work on both fundamental principles and applications of doping, focused primarily to doping of evaporated organic layers with molecular dopants. Recently, both p- and n-type molecular dopants have been developed that lead to efficient and stable doping of organic thin films. Due to doping, the conductivity of the doped layers increases several orders of magnitude and allows for quasi-Ohmic contacts between organic layers and metal electrodes. Besides reducing voltage losses, doping thus also gives design freedom in terms of transport layer thickness and electrode choice. The use of doping in applications like OLEDs and organic solar cells is highlighted in this review. Overall, controlled molecular doping can be considered as key enabling technology for many different organic device types that can lead to significant improvements in efficiencies and lifetimes. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Hybrid laser technology and doped biomaterials

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Miroslav; Zemek, Josef; Remsa, Jan; Mikšovský, Jan; Kocourek, Tomáš; Písařík, Petr; Trávníčková, Martina; Filová, Elena; Bačáková, Lucie

    2017-01-01

    Roč. 417, Sep (2017), s. 73-83 ISSN 0169-4332 R&D Projects: GA ČR(CZ) GA15-05864S Institutional support: RVO:68378271 ; RVO:67985823 Keywords : hybrid PLD * Cr: DLC * Ti: DLC. comparison of properties * in vitro tests Subject RIV: BM - Solid Matter Physics ; Magnetism; EI - Biotechnology ; Bionics (FGU-C) OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.); Biomaterials (as related to medical implants, devices, sensors) (FGU-C) Impact factor: 3.387, year: 2016

  13. Coval: improving alignment quality and variant calling accuracy for next-generation sequencing data.

    Directory of Open Access Journals (Sweden)

    Shunichi Kosugi

    Full Text Available Accurate identification of DNA polymorphisms using next-generation sequencing technology is challenging because of a high rate of sequencing error and incorrect mapping of reads to reference genomes. Currently available short read aligners and DNA variant callers suffer from these problems. We developed the Coval software to improve the quality of short read alignments. Coval is designed to minimize the incidence of spurious alignment of short reads, by filtering mismatched reads that remained in alignments after local realignment and error correction of mismatched reads. The error correction is executed based on the base quality and allele frequency at the non-reference positions for an individual or pooled sample. We demonstrated the utility of Coval by applying it to simulated genomes and experimentally obtained short-read data of rice, nematode, and mouse. Moreover, we found an unexpectedly large number of incorrectly mapped reads in 'targeted' alignments, where the whole genome sequencing reads had been aligned to a local genomic segment, and showed that Coval effectively eliminated such spurious alignments. We conclude that Coval significantly improves the quality of short-read sequence alignments, thereby increasing the calling accuracy of currently available tools for SNP and indel identification. Coval is available at http://sourceforge.net/projects/coval105/.

  14. The covalence effect of energy levels of ZnS:Mn2+

    International Nuclear Information System (INIS)

    Dong-Yang, Li; Mao-Lu, Du; Yi, Huang

    2013-01-01

    The contribution of the different covalence for t 2 and e orbitals must be considered in the investigation of the optical and magnetic properties of the transition metal ion in II–VI and III–V semiconductors. In present paper, two covalent parameters N t and N e associated with t 2 and e orbitals have been adopted to describe the covalence. The energy matrices considering the different covalence for t 2 and e orbitals have been provided for d 5 ions in crystal. These matrices show that the contribution from the Racah parameter A cannot be neglected in calculation of energy-level of d 5 ions in covalent crystal. The calculated results using the matrix show that the energy levels of 4 E and 4 A 1 states split, and the energy-level difference between 4 E and 4 A 1 states increases with increase of the different covalence between t 2 and e orbitals. These energy levels are always degenerate, when the different covalence for t 2 and e orbitals is neglected. By using the energy matrices, the energy-level of ZnS:Mn 2+ has been calculated. The calculated energy levels of ZnS:Mn 2+ are in good agreement with the experiments

  15. COVALENT IMMOBILIZATION OF INVERTASE ON EPOXY-ACTIVATED POLYANILINE FILMS

    Directory of Open Access Journals (Sweden)

    Loredana Vacareanu

    2013-08-01

    Full Text Available The growing interest in manufacturing and use of biosensors is their rapid and selective detection of the target analyte. The immobilization of the enzymes, onto the appropriate matrix is the key-step in the construction of biosensing devices, considerably affecting its performance. In this study, new polyaniline bearing epoxy groups was synthesized by electrochemical polymerization reactions, as adherent, green film deposited on electrode surface, and was further used as immobilization matrix for invertase enzyme. The immobilization was carried out by condensation reactions between the amino groups of the enzyme molecules and the epoxy groups of polyaniline film. The covalent attachment was achieved by simple immersing the epoxy-activated polyaniline in acetate buffer solution (10 mM, pH 6.0 containing 2mg/mL invertase, for 24 h at 4 ºC, by continuous stirring. The polyaniline films thus obtained were analyzed before and after the invertase attachment, by using FT-IR spectroscopy and SEM microscopy. The presence of the invertase was evaluated by measuring their activity, using UV-Vis spectroscopy, in the presence of a known amount of sucrose as a substrate. These tests, performed for three times under the same conditions, revealed that even after five washes of the polyaniline /invertase electrode to remove the unbounded enzyme, the enzyme remain attached on the polyaniline film, being able to hydrolyze the sucrose presented in the assay solutions.

  16. Characterising non-covalent interactions with the Cambridge Structural Database.

    Science.gov (United States)

    Lommerse, J P; Taylor, R

    1997-02-01

    This review describes how the CSD can be used to study non-covalent interactions. Several different types of information may be obtained. First, the relative frequencies of various interactions can be studied; for example, we have shown that the terminal oxygen atoms of phosphate groups accept hydrogen bonds far more often than the linkage oxygens. Secondly, information can be obtained about the geometries of nonbonded contacts; for example, hydrogen bonds to P-O groups rarely form along the extension of the P-O bond, whereas short contacts between oxygen and carbon-bound iodine show a strong preference for linear C-I ... O angles. Thirdly, the CSD can be searched for novel interactions which may be exploited in inhibitor design; for example, the I ... O contacts just mentioned, and N-H ... pi hydrogen bonds. Finally, the CSD can suggest synthetic targets for medicinal chemistry; for example, molecules containing delocalised electron deficient groups such as trimethylammonium, pyridinium, thaizolium and dinitrophenyl have a good chance of binding to an active-site tryptophan. Although the CSD contains small-molecule crystal structures, not protein-ligand complexes, there is considerable evidence that the contacts seen in the two types of structures are similar. We have illustrated this a number of times in the present review and additional evidence has been given previously by Klebe. The major advantages of the CSD are its size, diversity and experimental accuracy. For these reasons, it is a useful tool for modellers engaged in rational inhibitor design.

  17. Covalently Bonded Chitosan on Graphene Oxide via Redox Reaction

    Directory of Open Access Journals (Sweden)

    Víctor M. Castaño

    2013-03-01

    Full Text Available Carbon nanostructures have played an important role in creating a new field of materials based on carbon. Chemical modification of carbon nanostructures through grafting has been a successful step to improve dispersion and compatibility in solvents, with biomolecules and polymers to form nanocomposites. In this sense carbohydrates such as chitosan are extremely valuable because their functional groups play an important role in diversifying the applications of carbon nanomaterials. This paper reports the covalent attachment of chitosan onto graphene oxide, taking advantage of this carbohydrate at the nanometric level. Grafting is an innovative route to modify properties of graphene, a two-dimensional nanometric arrangement, which is one of the most novel and promising nanostructures. Chitosan grafting was achieved by redox reaction using different temperature conditions that impact on the morphology and features of graphene oxide sheets. Transmission Electron Microscopy, Fourier Transform Infrared, Raman and Energy Dispersive spectroscopies were used to study the surface of chitosan-grafted-graphene oxide. Results show a successful modification indicated by the functional groups found in the grafted material. Dispersions of chitosan-grafted-graphene oxide samples in water and hexane revealed different behavior due to the chemical groups attached to the graphene oxide sheet.

  18. Selective Covalent Conjugation of Phosphorothioate DNA Oligonucleotides with Streptavidin

    Directory of Open Access Journals (Sweden)

    Christof M. Niemeyer

    2011-08-01

    Full Text Available Protein-DNA conjugates have found numerous applications in the field of diagnostics and nanobiotechnology, however, their intrinsic susceptibility to DNA degradation by nucleases represents a major obstacle for many applications. We here report the selective covalent conjugation of the protein streptavidin (STV with phosphorothioate oligonucleotides (psDNA containing a terminal alkylthiolgroup as the chemically addressable linking unit, using a heterobifunctional NHS-/maleimide crosslinker. The psDNA-STV conjugates were synthesized in about 10% isolated yields. We demonstrate that the terminal alkylthiol group selectively reacts with the maleimide while the backbone sulfur atoms are not engaged in chemical conjugation. The novel psDNA-STV conjugates retain their binding capabilities for both biotinylated macromolecules and the complementary nucleic acid. Moreover, the psDNA-STV conjugate retained its binding capacity for complementary oligomers even after a nuclease digestion step, which effectively degrades deoxyribonucleotide oligomers and thus the binding capability of regular DNA-STV conjugates. The psDNA-STV therefore hold particular promise for applications e.g. in proteome research and novel biosensing devices, where interfering endogenous nucleic acids need to be removed from analytes by nuclease digestion.

  19. Self-Suspended Suspensions of Covalently Grafted Hairy Nanoparticles

    KAUST Repository

    Choudhury, Snehashis

    2015-03-17

    © 2015 American Chemical Society. Dispersions of small particles in liquids have been studied continuously for almost two centuries for their ability to simultaneously advance understanding of physical properties of fluids and their widespread use in applications. In both settings, the suspending (liquid) and suspended (solid) phases are normally distinct and uncoupled on long length and time scales. In this study, we report on the synthesis and physical properties of a novel family of covalently grafted nanoparticles that exist as self-suspended suspensions with high particle loadings. In such suspensions, we find that the grafted polymer chains exhibit unusual multiscale structural transitions and enhanced conformational stability on subnanometer and nanometer length scales. On mesoscopic length scales, the suspensions display exceptional homogeneity and colloidal stability. We attribute this feature to steric repulsions between grafted chains and the space-filling constraint on the tethered chains in the single-component self-suspended materials, which inhibits phase segregation. On macroscopic length scales, the suspensions exist as neat fluids that exhibit soft glassy rheology and, counterintuitively, enhanced elasticity with increasing temperature. This feature is discussed in terms of increased interpenetration of the grafted chains and jamming of the nanoparticles. (Chemical Presented).

  20. Hydrolytic Stability of Boronate Ester-Linked Covalent Organic Frameworks

    KAUST Repository

    Li, Huifang

    2018-01-30

    The stability of covalent organic frameworks (COFs) is essential to their applications. However, the common boronate ester-linked COFs are susceptible to attack by nucleophiles (such as water molecules) at the electron-deficient boron sites. To provide an understanding of the hydrolytic stability of the representative boronate ester-linked COF-5 and of the associated hydrolysis mechanisms, density functional theory (DFT) calculations were performed to characterize the hydrolysis reactions of the molecule formed by the condensation of 1,4-phenylenebis(boronic acid) (PBBA) and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) monomers; two cases were considered, one dealing with the freestanding molecule and the other with the molecule interacting with COF layers. It was found that the boronate ester (B–O) bond dissociation, which requires one H2O molecule, has a relatively high energy barrier of 22.3 kcal mol−1. However, the presence of an additional H2O molecule significantly accelerates hydrolysis by reducing the energy barrier by a factor of 3. Importantly, the hydrolysis of boronate ester bonds situated in a COF environment follows reaction pathways that are different and have increased energy barriers. These results point to an enhanced hydrolytic stability of COF-5 crystals.

  1. Covalently functionalized graphene sheets with biocompatible natural amino acids

    International Nuclear Information System (INIS)

    Mallakpour, Shadpour; Abdolmaleki, Amir; Borandeh, Sedigheh

    2014-01-01

    Graphene sheets were covalently functionalized with aromatic–aliphatic amino acids (phenylalanine and tyrosine) and aliphatic amino acids (alanine, isoleucine, leucine, methionine and valine) by simple and green procedure. For this aim, at first natural graphite was converted into graphene oxide (GO) through strong oxidation procedure; then, based on the surface-exposed epoxy and carboxylic acid groups in GO solid, its surface modification with naturally occurring amino acids, occurred easily throughout the corresponding nucleophilic substitution and condensation reactions. Amino acid functionalized graphene demonstrates stable dispersion in water and common organic solvents. Fourier transform infrared, Raman and X-ray photoelectron spectroscopies, X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy were used to investigate the nanostructures and properties of prepared materials. Each amino acid has different considerable effects on the structure and morphology of the pure graphite, from increasing the layer spacing to layer scrolling, based on their structures, functional groups and chain length. In addition, therogravimetric analysis was used for demonstrating a successful grafting of amino acid molecules to the surface of graphene.

  2. Unsynchronized resonance of covalent bonds in the superconducting state

    International Nuclear Information System (INIS)

    Costa, Marconi B.S.; Bastos, Cristiano C.; Pavao, Antonio C.

    2012-01-01

    Daft calculations performed on different cluster models of cuprates (LaBa 2 Cu 3 O 6.7 , La 1.85 Sr 0.15 CuO 4 , YBa 2 Cu 3 O 7 , TlBa 2 Ca 2 Cu 3 O 8.78 , HgBa 2 Ca 2 Cu 3 O 8.27 ), metallic systems (Nb 3 Ge, MgB 2 ) and the pnictide LaO 0.92 F 0.08 FeAs made evident the occurrence of un synchronized resonance of covalent bonds in the superconducting state, as predicted by Paling's resonating valence bond Rb) theory. For cuprates, the un synchronized resonance involves electron transfer between Cu atoms accompanied by a decrease in the charge of the La, Sr, Y and Ca atoms. For MgB 2 , electron transfer occurs in the Mg layer, while the B layer behaves as charge reservoir. For Nb 3 Ge, unsynchronized resonance occurs among the Ge atoms, which should be responsible for charge transfer. For LaO 0.92 F 0.08 FeAs, the results suggest that both La-O and Fe-As layers are involved in the mechanism of superconductivity. The identification of unsynchronized resonances in these systems provides evidence which supports RVB as a suitable theory for high-temperature superconductivity (high-TC). (author)

  3. Extending density functional embedding theory for covalently bonded systems.

    Science.gov (United States)

    Yu, Kuang; Carter, Emily A

    2017-12-19

    Quantum embedding theory aims to provide an efficient solution to obtain accurate electronic energies for systems too large for full-scale, high-level quantum calculations. It adopts a hierarchical approach that divides the total system into a small embedded region and a larger environment, using different levels of theory to describe each part. Previously, we developed a density-based quantum embedding theory called density functional embedding theory (DFET), which achieved considerable success in metals and semiconductors. In this work, we extend DFET into a density-matrix-based nonlocal form, enabling DFET to study the stronger quantum couplings between covalently bonded subsystems. We name this theory density-matrix functional embedding theory (DMFET), and we demonstrate its performance in several test examples that resemble various real applications in both chemistry and biochemistry. DMFET gives excellent results in all cases tested thus far, including predicting isomerization energies, proton transfer energies, and highest occupied molecular orbital-lowest unoccupied molecular orbital gaps for local chromophores. Here, we show that DMFET systematically improves the quality of the results compared with the widely used state-of-the-art methods, such as the simple capped cluster model or the widely used ONIOM method.

  4. Atom-scale covalent electrochemical modification of single-layer graphene on SiC substrates by diaryliodonium salts

    International Nuclear Information System (INIS)

    Gearba, Raluca I.; Mueller, Kory M.; Veneman, Peter A.; Holliday, Bradley J.; Chan, Calvin K.; Stevenson, Keith J.

    2015-01-01

    Owing to its high conductivity, graphene holds promise as an electrode for energy devices such as batteries and photovoltaics. However, to this end, the work function and doping levels in graphene need to be precisely tuned. One promising route for modifying graphene's electronic properties is via controlled covalent electrochemical grafting of molecules. We show that by employing diaryliodonium salts instead of the commonly used diazonium salts, spontaneous functionalization is avoided. This then allows for precise tuning of the grafting density. Moreover, by employing bis(4-nitrophenyl)iodonium(III) tetrafluoroborate (DNP) salt calibration curves, the surface functionalization density (coverage) of glassy carbon was controlled using cyclic voltammetry in varying salt concentrations. These electro-grafting conditions and calibration curves translated directly over to modifying single layer epitaxial graphene substrates (grown on insulating 6H-SiC (0 0 0 1)). In addition to quantifying the functionalization densities using electrochemical methods, samples with low grafting densities were characterized by low-temperature scanning tunneling microscopy (LT-STM). We show that the use of buffer-layer free graphene substrates is required for clear observation of the nitrophenyl modifications. Furthermore, atomically-resolved STM images of single site modifications were obtained, showing no preferential grafting at defect sites or SiC step edges as supposed previously in the literature. Most of the grafts exhibit threefold symmetry, but occasional extended modifications (larger than 4 nm) were observed as well

  5. Water activated doping and transport in multilayered germanane crystals

    International Nuclear Information System (INIS)

    Young, Justin R; Johnston-Halperin, Ezekiel; Chitara, Basant; Cultrara, Nicholas D; Arguilla, Maxx Q; Jiang, Shishi; Fan, Fan; Goldberger, Joshua E

    2016-01-01

    The synthesis of germanane (GeH) has opened the door for covalently functionalizable 2D materials in electronics. Herein, we demonstrate that GeH can be electronically doped by incorporating stoichiometric equivalents of phosphorus dopant atoms into the CaGe 2 precursor. The electronic properties of these doped materials show significant atmospheric sensitivity, and we observe a reduction in resistance by up to three orders of magnitude when doped samples are measured in water-containing atmospheres. This variation in resistance is a result of water activation of the phosphorus dopants. Transport measurements in different contact geometries show a significant anisotropy between in-plane and out-of-plane resistances, with a much larger out-of-plane resistance. These measurements along with finite element modeling results predict that the current distribution in top-contacted crystals is restricted to only the topmost, water activated crystal layers. Taken together, these results pave the way for future electronic and optoelectronic applications utilizing group IV graphane analogues. (paper)

  6. Sanctions for doping in sport

    Directory of Open Access Journals (Sweden)

    Mandarić Sanja

    2014-01-01

    Full Text Available Top-level sport imposes new and more demanding physical and psychological pressures, and the desire for competing, winning and selfassertion leads athletes into temptation to use prohibited substances in order to achieve the best possible results. Regardless of the fact that the adverse consequences of prohibited substances are well-known, prestige and the need to dominate sports arenas have led to their use in sports. Doping is one of the biggest issues in sport today, and the fight against it is a strategic objective on both global and national levels. World Anti-Doping Agency, the International Olympic Committee, international sports federations, national anti-doping agencies, national sports federations, as well as governments and their repressive apparatuses are all involved in the fight against doping in sport. This paper points to a different etymology and phenomenology of doping, the beginnings of doping in sport, sports doping scandals as well as the most important international instruments regulating this issue. Also, there is a special reference in this paper to the criminal and misdemeanor sanctions for doping in sport. In Serbia doping in sport is prohibited by the Law on Prevention of Doping in Sports which came into force in 2005 and which prescribes the measures and activities aimed at prevention of doping in sport. In this context, the law provides for the following three criminal offenses: use of doping substances, facilitating the use of doping substances, and unauthorized production and putting on traffic of doping substances. In addition, aiming at curbing the abuse of doping this law also provides for two violations. More frequent and repetitive doping scandals indicate that doping despite long-standing sanctions is still present in sports, which suggests that sanctions alone have not given satisfactory results so far.

  7. Magnetic properties of sulfur-doped graphene

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J. [Department of Physics and Astronomy, Clemson University, Clemson, SC (United States); Clemson Nanomaterial Center, Clemson University, Clemson, SC (United States); Park, H. [Department of Physics, The Ohio State University, Columbus, OH (United States); Podila, R., E-mail: rpodila@g.clemson.edu [Department of Physics and Astronomy, Clemson University, Clemson, SC (United States); Clemson Nanomaterial Center, Clemson University, Clemson, SC (United States); COMSET, Clemson University, Clemson, SC (United States); Wadehra, A. [Department of Physics, The Ohio State University, Columbus, OH (United States); Ayala, P. [Faculty of Physics, University of Vienna, Vienna (Austria); Oliveira, L.; He, J. [Department of Physics and Astronomy, Clemson University, Clemson, SC (United States); Zakhidov, A.A.; Howard, A. [Alan G. MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX (United States); Wilkins, J. [Department of Physics, The Ohio State University, Columbus, OH (United States); Rao, A.M., E-mail: arao@g.clemson.edu [Department of Physics and Astronomy, Clemson University, Clemson, SC (United States); Clemson Nanomaterial Center, Clemson University, Clemson, SC (United States); COMSET, Clemson University, Clemson, SC (United States)

    2016-03-01

    While studying magnetism of d- and f-electron systems has been consistently an active research area in physics, chemistry, and biology, there is an increasing interest in the novel magnetism of p-electron systems, especially in graphene and graphene-derived nanostructures. Bulk graphite is diamagnetic in nature, however, graphene is known to exhibit either a paramagnetic response or weak ferromagnetic ordering. Although many groups have attributed this magnetism in graphene to defects or unintentional magnetic impurities, there is a lack of compelling evidence to pinpoint its origin. To resolve this issue, we systematically studied the influence of entropically necessary intrinsic defects (e.g., vacancies, edges) and extrinsic dopants (e.g., S-dopants) on the magnetic properties of graphene. We found that the saturation magnetization of graphene decreased upon sulfur doping suggesting that S-dopants demagnetize vacancies and edges. Our density functional theory calculations provide evidence for: (i) intrinsic defect demagnetization by the formation of covalent bonds between S-dopant and edges/vacancies concurring with the experimental results, and (ii) a net magnetization from only zig-zag edges, suggesting that the possible contradictory results on graphene magnetism in the literature could stem from different defect-types. Interestingly, we observed peculiar local maxima in the temperature dependent magnetizations that suggest the coexistence of different magnetic phases within the same graphene samples. - Highlights: • Magnetic properties of pristine and S-doped graphene were investigated. • Pristine graphene with intrinsic defects exhibits a non-zero magnetic moment. • The addition of S-dopants was found to quench the magnetic ordering. • DFT calculations confirmed that magnetization in graphene arises from defects. • DFT calculations show S-dopants quench local magnetic moment of defect structures.

  8. Surface passivation for tight-binding calculations of covalent solids

    International Nuclear Information System (INIS)

    Bernstein, N

    2007-01-01

    Simulation of a cluster representing a finite portion of a larger covalently bonded system requires the passivation of the cluster surface. We compute the effects of an explicit hybrid orbital passivation (EHOP) on the atomic structure in a model bulk, three-dimensional, narrow gap semiconductor, which is very different from the wide gap, quasi-one-dimensional organic molecules where most passivation schemes have been studied in detail. The EHOP approach is directly applicable to minimal atomic orbital basis methods such as tight-binding. Each broken bond is passivated by a hybrid created from an explicitly expressed linear combination of basis orbitals, chosen to represent the contribution of the missing neighbour, e.g. a sp 3 hybrid for a single bond. The method is tested by computing the forces on atoms near a point defect as a function of cluster geometry. We show that, compared to alternatives such as pseudo-hydrogen passivation, the force on an atom converges to the correct bulk limit more quickly as a function of cluster radius, and that the force is more stable with respect to perturbations in the position of the cluster centre. The EHOP method also obviates the need for parameterizing the interactions between the system atoms and the passivating atoms. The method is useful for cluster calculations of non-periodic defects in large systems and for hybrid schemes that simulate large systems by treating finite regions with a quantum-mechanical model, coupled to an interatomic potential description of the rest of the system

  9. Covalent dimerization of ribulose bisphosphate carboxylase subunits by UV radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, R.M.B. [Universidade Tecnica, Lisbon (Portugal). Inst. Superior de Agronomia]|[Universidade Nova de Lisboa, Oeiras (Portugal). Instituto de Tecnologia Quimica e Biologica; Franco, E.; Teixeira, A.R.N. [Universidade Tecnica, Lisbon (Portugal). Inst. Superior de Agronomia

    1996-08-15

    The effect of UV radiation (UV-A, UV-B and UV-C) on ribulose bisphosphate carboxylase from a variety of plant species was examined. The exposition of plant leaves or the pure enzyme to UV radiation produced a UV-dependent accumulation of a 65 kDa polypeptide (P65). Different approaches were utilized to elucidate the origin and structure of P65: electrophoretic and fluorographic analyses of {sup 35}S-labelled ribulose biphosphate carboxylase exposed to UV radiation and immunological experiments using antibodies specific for P65, for the large and small subunits of ribulose biphosphate carboxylase and for high-molecular-mass aggregates of the enzyme. These studies revealed that P65 is a dimer, formed by the covalent, non-disulphide linkage of one small subunit with one large subunit of ribulose biphosphate carboxylase. For short periods of time (<1 h), the amount of P65 formed increased with the duration of the exposure to the UV radiation and with the energy of the radiation applied. Prolonged exposure to UV radiation (1-6 h) resulted in the formation of high-molecular-mass aggregates of ribulose biphosphate carboxylase. Formation of P65 was shown to depend on the native state of the protein, was stimulated by inhibitors of enzyme activity, and was inhibited by activators of enzyme activity. A UV-independent accumulation of P65 was also achieved by the in vitro incubation of plant crude extracts. However, the UV-dependent and the UV-independent formation of P65 seemed to occur by distinct molecular mechanisms. The UV-dependent accumulation of P65 was immunologically detected in all species examined, including Lemna minor, Arum italicum, Brassica oleracea, Triticum aestivum, Zea mays, Pisum sativum and Phaseolus vulgaris, suggesting that it may constitute a universal response to UV radiation, common to all photosynthetic tissues. (Author).

  10. Covalent dimerization of ribulose bisphosphate carboxylase subunits by UV radiation

    International Nuclear Information System (INIS)

    Ferreira, R.M.B.; Universidade Nova de Lisboa, Oeiras; Franco, E.; Teixeira, A.R.N.

    1996-01-01

    The effect of UV radiation (UV-A, UV-B and UV-C) on ribulose bisphosphate carboxylase from a variety of plant species was examined. The exposition of plant leaves or the pure enzyme to UV radiation produced a UV-dependent accumulation of a 65 kDa polypeptide (P65). Different approaches were utilized to elucidate the origin and structure of P65: electrophoretic and fluorographic analyses of 35 S-labelled ribulose biphosphate carboxylase exposed to UV radiation and immunological experiments using antibodies specific for P65, for the large and small subunits of ribulose biphosphate carboxylase and for high-molecular-mass aggregates of the enzyme. These studies revealed that P65 is a dimer, formed by the covalent, non-disulphide linkage of one small subunit with one large subunit of ribulose biphosphate carboxylase. For short periods of time (<1 h), the amount of P65 formed increased with the duration of the exposure to the UV radiation and with the energy of the radiation applied. Prolonged exposure to UV radiation (1-6 h) resulted in the formation of high-molecular-mass aggregates of ribulose biphosphate carboxylase. Formation of P65 was shown to depend on the native state of the protein, was stimulated by inhibitors of enzyme activity, and was inhibited by activators of enzyme activity. A UV-independent accumulation of P65 was also achieved by the in vitro incubation of plant crude extracts. However, the UV-dependent and the UV-independent formation of P65 seemed to occur by distinct molecular mechanisms. The UV-dependent accumulation of P65 was immunologically detected in all species examined, including Lemna minor, Arum italicum, Brassica oleracea, Triticum aestivum, Zea mays, Pisum sativum and Phaseolus vulgaris, suggesting that it may constitute a universal response to UV radiation, common to all photosynthetic tissues. (Author)

  11. Adaptive polymeric nanomaterials utilizing reversible covalent and hydrogen bonding

    Science.gov (United States)

    Neikirk, Colin

    Adaptive materials based on stimuli responsive and reversible bonding moieties are a rapidly developing area of materials research. Advances in supramolecular chemistry are now being adapted to novel molecular architectures including supramolecular polymers to allow small, reversible changes in molecular and nanoscale structure to affect large changes in macroscale properties. Meanwhile, dynamic covalent chemistry provides a complementary approach that will also play a role in the development of smart adaptive materials. In this thesis, we present several advances to the field of adaptive materials and also provide relevant insight to the areas of polymer nanocomposites and polymer nanoparticles. First, we have utilized the innate molecular recognition and binding capabilities of the quadruple hydrogen bonding group ureidopyrimidinone (UPy) to prepare supramolecular polymer nanocomposites based on supramolecular poly(caprolactone) which show improved mechanical properties, but also an increase in particle aggregation with nanoparticle UPy functionalization. We also present further insight into the relative effects of filler-filler, filler-matrix, and matrix-matrix interactions using a UPy side-chain functional poly(butyl acrylate). These nanocomposites have markedly different behavior depending on the amount of UPy sidechain functionality. Meanwhile, our investigations of reversible photo-response showed that coumarin functionality in polymer nanoparticles not only facilitates light mediated aggregation/dissociation behavior, but also provides a substantial overall reduction in particle size and improvement in nanoparticle stability for particles prepared by Flash NanoPrecipitation. Finally, we have combined these stimuli responsive motifs as a starting point for the development of multiresponsive adaptive materials. The synthesis of a library of multifunctional materials has provided a strong base for future research in this area, although our initial

  12. First-principle study of single TM atoms X (X=Fe, Ru or Os) doped monolayer WS2 systems

    Science.gov (United States)

    Zhu, Yuan-Yan; Zhang, Jian-Min

    2018-05-01

    We report the structural, magnetic and electronic properties of the pristine and single TM atoms X (X = Fe, Ru or Os) doped monolayer WS2 systems based on first-principle calculations. The results show that the W-S bond shows a stronger covalent bond, but the covalency is obviously weakened after the substitution of W atom with single X atoms, especially for Ru (4d75s1) with the easily lost electronic configuration. The smaller total energies of the doped systems reveal that the spin-polarized states are energetically favorable than the non-spin-polarized states, and the smallest total energy of -373.918 eV shows the spin-polarized state of the Os doped monolayer WS2 system is most stable among three doped systems. In addition, although the pristine monolayer WS2 system is a nonmagnetic-semiconductor with a direct band gap of 1.813 eV, single TM atoms Fe and Ru doped monolayer WS2 systems transfer to magnetic-HM with the total moments Mtot of 1.993 and 1.962 μB , while single TM atom Os doped monolayer WS2 systems changes to magnetic-metal with the total moments Mtot of 1.569 μB . Moreover, the impurity states with a positive spin splitting energies of 0.543, 0.276 and 0.1999 eV near the Fermi level EF are mainly contributed by X-dxy and X-dx2-y2 states hybridized with its nearest-neighbor atom W-dz2 states for Fe, Ru and Os doped monolayer WS2 system, respectively. Finally, we hope that the present study on monolayer WS2 will provide a useful theoretical guideline for exploring low-dimensional spintronic materials in future experiments.

  13. Covalent modification of graphene and graphite using diazonium chemistry: tunable grafting and nanomanipulation.

    Science.gov (United States)

    Greenwood, John; Phan, Thanh Hai; Fujita, Yasuhiko; Li, Zhi; Ivasenko, Oleksandr; Vanderlinden, Willem; Van Gorp, Hans; Frederickx, Wout; Lu, Gang; Tahara, Kazukuni; Tobe, Yoshito; Uji-I, Hiroshi; Mertens, Stijn F L; De Feyter, Steven

    2015-05-26

    We shine light on the covalent modification of graphite and graphene substrates using diazonium chemistry under ambient conditions. We report on the nature of the chemical modification of these graphitic substrates, the relation between molecular structure and film morphology, and the impact of the covalent modification on the properties of the substrates, as revealed by local microscopy and spectroscopy techniques and electrochemistry. By careful selection of the reagents and optimizing reaction conditions, a high density of covalently grafted molecules is obtained, a result that is demonstrated in an unprecedented way by scanning tunneling microscopy (STM) under ambient conditions. With nanomanipulation, i.e., nanoshaving using STM, surface structuring and functionalization at the nanoscale is achieved. This manipulation leads to the removal of the covalently anchored molecules, regenerating pristine sp(2) hybridized graphene or graphite patches, as proven by space-resolved Raman microscopy and molecular self-assembly studies.

  14. 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...

  15. Use of Functionalized Carbon Nanotubes for Covalent Attachment of Nanotubes to Silicon

    Science.gov (United States)

    Tour, James M.; Dyke, Christopher A.; Maya, Francisco; Stewart, Michael P.; Chen, Bo; Flatt, Austen K.

    2012-01-01

    The purpose of the invention is to covalently attach functionalized carbon nanotubes to silicon. This step allows for the introduction of carbon nanotubes onto all manner of silicon surfaces, and thereby introduction of carbon nano - tubes covalently into silicon-based devices, onto silicon particles, and onto silicon surfaces. Single-walled carbon nanotubes (SWNTs) dispersed as individuals in surfactant were functionalized. The nano - tube was first treated with 4-t-butylbenzenediazonium tetrafluoroborate to give increased solubility to the carbon nanotube; the second group attached to the sidewall of the nanotube has a silyl-protected terminal alkyne that is de-protected in situ. This gives a soluble carbon nanotube that has functional groups appended to the sidewall that can be attached covalently to silicon. This reaction was monitored by UV/vis/NJR to assure direct covalent functionalization.

  16. Construction and repair of highly ordered 2D covalent networks by chemical equilibrium regulation.

    Science.gov (United States)

    Guan, Cui-Zhong; Wang, Dong; Wan, Li-Jun

    2012-03-21

    The construction of well-ordered 2D covalent networks via the dehydration of di-borate aromatic molecules was successfully realized through introducing a small amount of water into a closed reaction system to regulate the chemical equilibrium.

  17. Nucleation and Growth of Covalent Organic Frameworks from Solution: The Example of COF-5

    KAUST Repository

    Li, Haoyuan; Chavez, Anton D.; Li, Huifang; Li, Hong; Dichtel, William R.; Bredas, Jean-Luc

    2017-01-01

    The preparation of two-dimensional covalent organic frameworks (2D COFs) with large crystalline domains and controlled morphology is necessary for realizing the full potential of their atomically precise structures and uniform, tailorable porosity

  18. Local Electronic Structure of a Single-Layer Porphyrin-Containing Covalent Organic Framework

    KAUST Repository

    Chen, Chen; Joshi, Trinity; Li, Huifang; Chavez, Anton D.; Pedramrazi, Zahra; Liu, Pei-Nian; Li, Hong; Dichtel, William R.; Bredas, Jean-Luc; Crommie, Michael F.

    2017-01-01

    We have characterized the local electronic structure of a porphyrin-containing single-layer covalent organic framework (COF) exhibiting a square lattice. The COF monolayer was obtained by the deposition of 2,5-dimethoxybenzene-1,4-dicarboxaldehyde

  19. INFLUENCIA DE LA NITRURACIÓN POR PLASMA SOBRE EL COMPORTAMIENTO A LA CORROSIÓN Y LA ADHESIÓN DE RECUBRIMIENTOS DLC SOBRE ACERO INOXIDABLE AISI 420

    Directory of Open Access Journals (Sweden)

    Jorge N. Pecina

    2016-01-01

    Full Text Available En este trabajo se estudió el comportamiento a la corrosió n y la adhesión de dos rec ubrimientos DLC (“Diamond Like Carbon ” , “Soft” y “Hard”, depositados por PACVD (“Plasma Assisted Chemical Vapour Deposition” sobre acero AISI 420, templado y revenido y /o nitrurado por plasma . Se analizaron por espectroscopía Raman y midió dureza en superficie. Se observó la microestructura por OM y SEM. Se realizaron pruebas de adhesión con indentación Rockwell C . S e practicaron ensayos de Niebla Salina e inmersión en HCl . Los DLC “ Soft ” presentaron una dureza de 5 00 HV y un espesor de 2 0 μm , mientras que los “ Hard ” tuvieron 1400 HV y 2 ,5 μm. Ambos recubrimientos presentaron bajo coeficiente de fricción y buena adhesión sobre el sustrato nitrurado . También presentaron buena resistencia a la corrosión atmosférica. En HCl el DLC retardó la degradación que se presentó rápidamente en las muestras sin recubrir.

  20. Effect of metal doping on structural characteristics of amorphous carbon system: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaowei; Zhang, Dong [Key Laboratory of Marine Materials and Related Technologies, Key Laboratory of Marine Materials and Protective Technologies of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Lee, Kwang-Ryeol, E-mail: krlee@kist.re.kr [Computational Science Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Wang, Aiying, E-mail: aywang@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Key Laboratory of Marine Materials and Protective Technologies of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2016-05-31

    First-principles calculation was performed to investigate the effect of metal doping on the structural characteristics of amorphous carbon system, and the 3d transition metals (TM) were particularly selected as representative case. Results showed that the total energy in TM–C systems caused by distorting the bond angles was reduced distinctly for comparison with that in C–C system. Further electronic structure revealed that as the 3d electrons of doped TM increased, the bond characteristic of highest occupied molecular orbital changed from bonding (Sc, Ti) to nonbonding (V, Cr, Mn, Fe) and finally to antibonding (Co, Ni, Cu) between the TM and C atoms. Meanwhile, the TM–C bond presented a mixture of the covalent and ionic characters. The decrease of strength and directionality of TM–C bonds resulted in the total energy change upon bond angle distortion, which demonstrated that the bond characteristics played an important role in reducing residual stress of TM-doped amorphous carbon systems. - Highlights: • The bond characteristics as 3d electrons changed from bonding, nonbonding to antibonding. • The TM–C bond was a mixture of covalent and ionic characters. • Reduced strength and directionality of TM–C bond led to small distortion energy change. • The weak TM–C bond accounted for the reduced compressive stress caused by TM.

  1. Covalent Crosslinking of Porous Poly(Ionic Liquid) Membrane via a Triazine Network

    OpenAIRE

    Täuber, Karoline; Dani, Alessandro; Yuan, Jiayin

    2017-01-01

    Porous poly(ionic liquid) membranes that were prepared via electrostatic cross-linking were subsequently covalently cross-linked via formation of a 1,3,5-triazine network. The additional covalent cross-links do not affect the pore size and pore size distribution of the membranes and stabilize them towards salt solutions of high ionic strength, enabling the membranes to work in a broader environmental window.

  2. The Chemistry and Biochemistry of Heme c: Functional Bases for Covalent Attachment

    OpenAIRE

    Bowman, Sarah E. J.; Bren, Kara L.

    2008-01-01

    A discussion of the literature concerning the synthesis, function, and activity of heme c-containing proteins is presented. Comparison of the properties of heme c, which is covalently bound to protein, is made to heme b, which is bound noncovalently. A question of interest is why nature uses biochemically expensive heme c in many proteins when its properties are expected to be similar to heme b. Considering the effects of covalent heme attachment on heme conformation and on the proximal histi...

  3. Tissue Plasminogen Activator Binding to Superparamagnetic Iron Oxide Nanoparticle—Covalent Versus Adsorptive Approach

    Science.gov (United States)

    Friedrich, Ralf P.; Zaloga, Jan; Schreiber, Eveline; Tóth, Ildikó Y.; Tombácz, Etelka; Lyer, Stefan; Alexiou, Christoph

    2016-06-01

    Functionalized superparamagnetic iron oxide nanoparticles are frequently used to develop vehicles for drug delivery, hyperthermia, and photodynamic therapy and as tools used for magnetic separation and purification of proteins or for biomolecular imaging. Depending on the application, there are various possible covalent and non-covalent approaches for the functionalization of particles, each of them shows different advantages and disadvantages for drug release and activity at the desired location.

  4. Contribution of the covalent and the Van der Waals force to the nuclear binding

    International Nuclear Information System (INIS)

    Rosina, M.; Povh, B.

    1994-01-01

    The contribution of the covalent and the Van der Waals force to the nuclear binding is estimated in a simplified model for medium distance of about 1 fm. It is shown how colour effects suppress these two forces as compared to the case of the forces between atoms. The covalent and the Van der Waals force represent a minor though noticeable component of the nuclear force. (orig.)

  5. Covalent modification of serum transferrin with phospholipid and incorporation into liposomal membranes

    DEFF Research Database (Denmark)

    Afzelius, P; Demant, E J; Hansen, Gert Helge

    1989-01-01

    A method is described for incorporation of water-soluble proteins into liposomal membranes using covalent protein-phospholipid conjugates in detergent solution. A disulfide derivative of phosphatidylethanolamine containing a reactive N-hydroxysuccinimide ester group is synthesized, and the deriva......A method is described for incorporation of water-soluble proteins into liposomal membranes using covalent protein-phospholipid conjugates in detergent solution. A disulfide derivative of phosphatidylethanolamine containing a reactive N-hydroxysuccinimide ester group is synthesized...

  6. The covalent effect on the energy levels of d3 ions in tetragonal compounds

    International Nuclear Information System (INIS)

    Li, Dong-Yang; Du, Mao-Lu

    2015-01-01

    For d 3 ions in covalent compounds with tetragonal symmetry, this paper presents a complete energy matrix, in which the different covalence of t 2 and e orbitals is considered not only in the electrostatic repulsions part of energy matrix elements but also in the crystal-field potential part of energy matrix elements. With taking and no taking the crystal field parameter B 00 0 into account, the effect of covalence on the energy levels of d 3 ions system were investigated, respectively. The investigation shows that it is very necessary for considering the different covalence of t 2 and e orbitals in both electrostatic repulsions part and crystal-field potential part when the optical properties of d 3 ions in strong covalent compounds with tetragonal symmetry is investigated. On the other hand, the crystal field parameter B 00 0 has a significant effect on the energy levels, and should be considered in investigations of d 3 ions in strong covalent compounds with tetragonal symmetry. Application to calculating the energy levels for Co 2+ in CdGa 2 Se 4 , the calculated results are in agreement with the experiment data

  7. Non-covalently functionalized carbon nanostructures for synthesizing carbon-based hybrid nanomaterials.

    Science.gov (United States)

    Li, Haiqing; Song, Sing I; Song, Ga Young; Kim, Il

    2014-02-01

    Carbon nanostructures (CNSs) such as carbon nanotubes, graphene sheets, and nanodiamonds provide an important type of substrate for constructing a variety of hybrid nanomaterials. However, their intrinsic chemistry-inert surfaces make it indispensable to pre-functionalize them prior to immobilizing additional components onto their surfaces. Currently developed strategies for functionalizing CNSs include covalent and non-covalent approaches. Conventional covalent treatments often damage the structure integrity of carbon surfaces and adversely affect their physical properties. In contrast, the non-covalent approach offers a non-destructive way to modify CNSs with desired functional surfaces, while reserving their intrinsic properties. Thus far, a number of surface modifiers including aromatic compounds, small-molecular surfactants, amphiphilic polymers, and biomacromolecules have been developed to non-covalently functionalize CNS surfaces. Mediated by these surface modifiers, various functional components such as organic species and inorganic nanoparticles were further decorated onto their surfaces, resulting in versatile carbon-based hybrid nanomaterials with broad applications in chemical engineering and biomedical areas. In this review, the recent advances in the generation of such hybrid nanostructures based on non-covalently functionalized CNSs will be reviewed.

  8. Enhancement of diffraction efficiency of laminar-type diffraction gratings overcoated with diamond-like carbon (DLC) in soft x-ray region

    Energy Technology Data Exchange (ETDEWEB)

    Koike, Masato, E-mail: koike.masato@jaea.go.jp; Imazono, Takashi [Quantum Beam Science Center, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215 Japan (Japan); Nagano, Tetsuya; Sasai, Hiroyuki; Oue, Yuki; Yonezawa, Zeno; Kuramoto, Satoshi [Device Dept., Shimadzu Corp., 1Nishinokyo-Kuwabara-cho, Nakagyo-ku, Kyoto 604-8511 Japan (Japan); Terauchi, Masami [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 Japan (Japan); Takahashi, Hideyuki [Science Equipment Sales Dept., JEOL Ltd., 2-1-1 Ohtemachi, Chiyoda-ku, Tokyo 100-0004 Japan (Japan); Notoya, Satoshi; Murano, Takanori [SA Business Unit, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 Japan (Japan)

    2016-07-27

    Boron is the critical trace element in the production of high quality steel, creating a great demand for an efficient detection method of the B-K emission band at around 6.76 nm. To meet this demand we made a simulation study and obtained a practical method to improve the diffraction efficiency of metal-coated laminar-type gratings for a grazing incidence flat-field spectrograph by overcoating a sufficiently transparent high-density material. In the simulation the diffraction efficiency in a spectral region of 3.5-8.5 nm was computed for several combinations of overcoating materials and coating metals, with various thicknesses of the overcoating layer. The result obtained are: (1) the best overcoating material is high-density diamond-like carbon (DLC) having a density of 3.1 g/cm{sup 3}, (2) its optimum thickness is 24 nm at an angle of incidence of 87.0°, and (3) with this thickness the first-order diffraction efficiency is expected to reach 29.7 %, which well exceeds 15.6 % for Ni-coated (or 14.1 % for Au-coated) grating.

  9. Nanostructures based in boro nitride thin films deposited by PLD onto Si/Si{sub 3}N{sub 4}/DLC substrate

    Energy Technology Data Exchange (ETDEWEB)

    Roman, W S; Riascos, H [Grupo Plasma, Laser y Aplicaciones, Universidad Tecnologica de Pereira (Colombia); Caicedo, J C [Grupo de PelIculas Delgadas, Universidad del Valle, Cali (Colombia); Ospina, R [Laboratorio de Plasma, Universidad Nacional de Colombia, sede Manizales (Colombia); Tirado-MejIa, L, E-mail: hriascos@utp.edu.c [Laboratorio de Optoelectronica, Universidad del Quindio (Colombia)

    2009-05-01

    Diamond-like carbon and boron nitride were deposited like nanostructered bilayer on Si/Si{sub 3}N{sub 4} substrate, both with (100) crystallographic orientation, these films were deposited through pulsed laser technique (Nd: YAG: 8 Jcm{sup -2}, 9ns). Graphite (99.99%) and boron nitride (99.99%) targets used to growth the films in argon atmosphere. The thicknesses of bilayer were determined with a perfilometer, active vibration modes were analyzed using infrared spectroscopy (FTIR), finding bands associated around 1400 cm{sup -1} for B - N bonding and bands around 1700 cm{sup -1} associated with C=C stretching vibrations of non-conjugated alkenes and azometinic groups, respectively. The crystallites of thin films were analyzed using X-ray diffraction (XRD) and determinated the h-BN (0002), alpha-Si{sub 3}N{sub 4} (101) phases. The aim of this study is to relate the dependence on physical and chemical characteristics of the system Si/Si{sub 3}N{sub 4}/DLC/BN with gas pressure adjusted at the 1.33, 2.67 and 5.33 Pa values.

  10. Fluorine and sulfur simultaneously co-doped suspended graphene

    Science.gov (United States)

    Struzzi, C.; Sezen, H.; Amati, M.; Gregoratti, L.; Reckinger, N.; Colomer, J.-F.; Snyders, R.; Bittencourt, C.; Scardamaglia, M.

    2017-11-01

    Suspended graphene flakes are exposed simultaneously to fluorine and sulfur ions produced by the μ-wave plasma discharge of the SF6 precursor gas. The microscopic and spectroscopic analyses, performed by Raman spectroscopy, scanning electron microscopy and photoelectron spectromicroscopy, show the homogeneity in functionalization yield over the graphene flakes with F and S atoms covalently bonded to the carbon lattice. This promising surface shows potential for several applications ranging from biomolecule immobilization to lithium battery and hydrogen storage devices. The present co-doping process is an optimal strategy to engineer the graphene surface with a concurrent hydrophobic character, thanks to the fluorine atoms, and a high affinity with metal nanoparticles due to the presence of sulfur atoms.

  11. BLOOD DOPING AND RISKS

    Directory of Open Access Journals (Sweden)

    Goran Vasić

    2015-05-01

    Full Text Available Doping is the way in which athletes misuse of chemicals and other types of medical interventions (eg, blood replacement, try to get ahead in the results of other athletes or their performance at the expense of their own health. The aim of this work is the analysis of blood doping and the display of negative consequences that this way of increasing capabilities brings. Method: The methodological work is done descriptively. Results: Even in 1972 at the Stockholm Institute for gymnastics and sport, first Dr. Bjorn Ekblom started having blood doping. Taken from the blood, athletes through centifuge separating red blood cells from blood plasma, which is after a month of storage in the fridge, every athlete back into the bloodstream. Tests aerobic capacity thereafter showed that the concerned athletes can run longer on average for 25% of the treadmill than before. Discussion: Blood doping carries with it serious risks, excessive amount of red cells “thickens the blood,” increased hematocrit, which reduces the heart’s ability to pump blood to the periphery. All this makes it difficult for blood to flow through blood vessels, and there is a great danger that comes to a halt in the circulation, which can cause cardiac arrest, stroke, pulmonary edema, and other complications that can be fatal.

  12. Doped barium titanate nanoparticles

    Indian Academy of Sciences (India)

    Wintec

    nese doped BaTiO3 ceramics, sintered at 1400°C in air, changes from tetragonal to hexagonal between 0⋅5 and. 1⋅7 mole% of manganese (Langhammer et al 2000). As a driving force of the transformation from the cubic to the hexagonal crystal structure, the influence of the Jahn–. Teller distortion is proposed. The grain ...

  13. Covalent electron transfer chemistry of graphene with diazonium salts.

    Science.gov (United States)

    Paulus, Geraldine L C; Wang, Qing Hua; Strano, Michael S

    2013-01-15

    Graphene is an atomically thin, two-dimensional allotrope of carbon with exceptionally high carrier mobilities, thermal conductivity, and mechanical strength. From a chemist's perspective, graphene can be regarded as a large polycyclic aromatic molecule and as a surface without a bulk contribution. Consequently, chemistries typically performed on organic molecules and surfaces have been used as starting points for the chemical functionalization of graphene. The motivations for chemical modification of graphene include changing its doping level, opening an electronic band gap, charge storage, chemical and biological sensing, making new composite materials, and the scale-up of solution-processable graphene. In this Account, we focus on graphene functionalization via electron transfer chemistries, in particular via reactions with aryl diazonium salts. Because electron transfer chemistries depend on the Fermi energy of graphene and the density of states of the reagents, the resulting reaction rate depends on the number of graphene layers, edge states, defects, atomic structure, and the electrostatic environment. We limit our Account to focus on pristine graphene over graphene oxide, because free electrons in the latter are already bound to oxygen-containing functionalities and the resulting chemistries are dominated by localized reactivity and defects. We describe the reaction mechanism of diazonium functionalization of graphene and show that the reaction conditions determine the relative degrees of chemisorption and physisorption, which allows for controlled modulation of the electronic properties of graphene. Finally we discuss different applications for graphene modified by this chemistry, including as an additive in polymer matrices, as biosensors when coupled with cells and biomolecules, and as catalysts when combined with nanoparticles.

  14. The significant role of covalency in determining the ground state of cobalt phthalocyanines molecule

    Directory of Open Access Journals (Sweden)

    Jing Zhou

    2016-03-01

    Full Text Available To shed some light on the metal 3d ground state configuration of cobalt phthalocyanines system, so far in debate, we present an investigation by X-ray absorption spectroscopy (XAS at Co L2,3 edge and theoretical calculation. The density functional theory calculations reveal highly anisotropic covalent bond between central cobalt ion and nitrogen ligands, with the dominant σ donor accompanied by weak π-back acceptor interaction. Our combined experimental and theoretical study on the Co-L2,3 XAS spectra demonstrate a robust ground state of 2A1g symmetry that is built from 73% 3d7 character and 27% 3 d 8 L ¯ ( L ¯ denotes a ligand hole components, as the first excited-state with 2Eg symmetry lies about 158 meV higher in energy. The effect of anisotropic and isotropic covalency on the ground state was also calculated and the results indicate that the ground state with 2A1g symmetry is robust in a large range of anisotropic covalent strength while a transition of ground state from 2A1g to 2Eg configuration when isotropic covalent strength increases to a certain extent. Here, we address a significant anisotropic covalent effect of short Co(II-N bond on the ground state and suggest that it should be taken into account in determining the ground state of analogous cobalt complexes.

  15. Tough Self-Healing Elastomers by Molecular Enforced Integration of Covalent and Reversible Networks.

    Science.gov (United States)

    Wu, Jinrong; Cai, Li-Heng; Weitz, David A

    2017-10-01

    Self-healing polymers crosslinked by solely reversible bonds are intrinsically weaker than common covalently crosslinked networks. Introducing covalent crosslinks into a reversible network would improve mechanical strength. It is challenging, however, to apply this concept to "dry" elastomers, largely because reversible crosslinks such as hydrogen bonds are often polar motifs, whereas covalent crosslinks are nonpolar motifs. These two types of bonds are intrinsically immiscible without cosolvents. Here, we design and fabricate a hybrid polymer network by crosslinking randomly branched polymers carrying motifs that can form both reversible hydrogen bonds and permanent covalent crosslinks. The randomly branched polymer links such two types of bonds and forces them to mix on the molecular level without cosolvents. This enables a hybrid "dry" elastomer that is very tough with fracture energy 13500 Jm -2 comparable to that of natural rubber. Moreover, the elastomer can self-heal at room temperature with a recovered tensile strength 4 MPa, which is 30% of its original value, yet comparable to the pristine strength of existing self-healing polymers. The concept of forcing covalent and reversible bonds to mix at molecular scale to create a homogenous network is quite general and should enable development of tough, self-healing polymers of practical usage. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Ab initio investigation of Al- and Ga-doped single-walled boron nitride nanotubes as ammonia sensor

    International Nuclear Information System (INIS)

    Soltani, Alireza; Raz, Shima Ghafouri; Rezaei, Vahid Joveini; Dehno Khalaji, Aliakbar; Savar, Mohammad

    2012-01-01

    Highlights: ► The electronic properties of NH 3 on Al- and Ga-doped (8, 0) and (5, 5) BNNT are studied. ► The adsorption energy for NH 3 on Al-doped (8, 0) BNNT is higher than that of Ga-doped (8, 0) BNNT. ► The relation between adsorption energy and charge transfer was investigated. - Abstract: We performed first-principles calculations on the ammonia (NH 3 ) adsorption properties with zigzag and armchair single-walled BN nanotubes (SWBNNTs) using B3LYP/6-31G* basis set implemented in Gaussian 98 program. We considered the ammonia adsorption on structural and electronic properties of Al- and Ga-doped (8, 0), (5, 5) BNNTs. The adsorption energy for the most stable configuration of NH 3 on Al-doped (8, 0) BNNT is about −0.182 eV, which is typical for the chemisorptions. We determined that both aluminum and gallium doping can significantly enhance the adsorption energy of NH 3 /BNNTs complexes. Our electronic results reveal that there is a significant orbital hybridization between two species in adsorption process being an evidence of covalent interaction.

  17. Antibacterial and Tribological Performance of Carbonitride Coatings Doped with W, Ti, Zr, or Cr Deposited on AISI 316L Stainless Steel

    Science.gov (United States)

    Yao, Sun-Hui; Su, Yen-Liang; Lai, Yu-Cheng

    2017-01-01

    Carbonitride (CNx) coatings have existed for several decades but are not well understood. Related studies have indicated that CNx coatings exhibit behaviors comparable to diamond-like carbon (DLC) coatings. Metal-doped CNx coatings are expected to show superior performance to single CNx coatings. In this study, a CNx coating and a group of CNx coatings with 6 at. % metal doping (W, Ti, Zr, or Cr) were prepared on biograde AISI 316L stainless steel (SS316L) substrates, and they were then characterized and studied for antibacterial and wear performance. The microstructure, constituent phase, nanohardness, adhesion, surface roughness, and contact angle were evaluated. The antimicrobial test used Staphylococcus aureus and followed the Japanese Industrial Standard JIS Z 2801:2010. Finally, the wear behavior was assessed. The results showed that the CNx coating was a composite of amorphous CNx and amorphous C structures. The metal doping caused crystalline metal carbides/nitrides to form in the CNx coatings, which weakened their overall integrity. All the coatings showed antimicrobial ability for the SS316L samples. The CNx-Zr coating, the surface of which had the highest hydrophilicity, produced the best antibacterial performance. However, the CNx-Zr coating showed lower wear resistance than the CNx-W and CNx-Ti coatings. The CNx-Ti coating with a highly hydrophilic surface exhibited the lowest antibacterial ability. PMID:29039782

  18. Antibacterial and Tribological Performance of Carbonitride Coatings Doped with W, Ti, Zr, or Cr Deposited on AISI 316L Stainless Steel

    Directory of Open Access Journals (Sweden)

    Sun-Hui Yao

    2017-10-01

    Full Text Available Carbonitride (CNx coatings have existed for several decades but are not well understood. Related studies have indicated that CNx coatings exhibit behaviors comparable to diamond-like carbon (DLC coatings. Metal-doped CNx coatings are expected to show superior performance to single CNx coatings. In this study, a CNx coating and a group of CNx coatings with 6 at. % metal doping (W, Ti, Zr, or Cr were prepared on biograde AISI 316L stainless steel (SS316L substrates, and they were then characterized and studied for antibacterial and wear performance. The microstructure, constituent phase, nanohardness, adhesion, surface roughness, and contact angle were evaluated. The antimicrobial test used Staphylococcus aureus and followed the Japanese Industrial Standard JIS Z 2801:2010. Finally, the wear behavior was assessed. The results showed that the CNx coating was a composite of amorphous CNx and amorphous C structures. The metal doping caused crystalline metal carbides/nitrides to form in the CNx coatings, which weakened their overall integrity. All the coatings showed antimicrobial ability for the SS316L samples. The CNx-Zr coating, the surface of which had the highest hydrophilicity, produced the best antibacterial performance. However, the CNx-Zr coating showed lower wear resistance than the CNx-W and CNx-Ti coatings. The CNx-Ti coating with a highly hydrophilic surface exhibited the lowest antibacterial ability.

  19. Data in support of covalent attachment of tyrosinase onto cyanuric chloride crosslinked magnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    Kourosh Abdollahi

    2016-12-01

    Full Text Available Preparation and characterization of cross linked amine-functionalized magnetic nanoparticles as an appropriate support for covalent immobilization on tyrosinase was presented in the study "Covalent immobilization of tyrosinase onto cyanuric chloride crosslinked amine-functionalized superparamagnetic nanoparticles: synthesis and characterization of the recyclable nanobiocatalyst" (Abdollahi et al., 2016 [1]. Herein, complementary data regarding X-ray powder diffraction (XRD to characterize the synthesized magnetic nanoparticles, and transmission electron microscopy (TEM to determine the size and morphology of tyrosinase immobilized magnetic nanoparticles (tyrosinase-MNPs were reported. The purification results of the extracted tyrosinase from mushroom Agaricus bisporus were provided in a purification table. The covalent immobilization of tyrosinase onto cyanuric chloride functionalized magnetic nanoparticles was proved by performing thermo-gravimetric and energy-dispersive X-ray spectroscopy analyses. The operational stability of immobilized tyrosinase was investigated by incubating tyrosinase-MNPs at different pH and temperatures.

  20. Unanticipated C=C bonds in covalent monolayers on silicon revealed by NEXAFS.

    Science.gov (United States)

    Lee, Michael V; Lee, Jonathan R I; Brehmer, Daniel E; Linford, Matthew R; Willey, Trevor M

    2010-02-02

    Interfaces are crucial to material properties. In the case of covalent organic monolayers on silicon, molecular structure at the interface controls the self-assembly of the monolayers, which in turn influences the optical properties and electrical transport. These properties intrinsically affect their application in biology, tribology, optics, and electronics. We use near-edge X-ray absorption fine structure spectroscopy to show that the most basic covalent monolayers formed from 1-alkenes on silicon retain a double bond in one-fifth to two-fifths of the resultant molecules. Unsaturation in the predominantly saturated monolayers will perturb the regular order and affect the dependent properties. The presence of unsaturation in monolayers produced by two different methods also prompts the re-evaluation of other radical-based mechanisms for forming covalent monolayers on silicon.

  1. Applications of covalent organic frameworks (COFs): From gas storage and separation to drug delivery

    Institute of Scientific and Technical Information of China (English)

    Ming-Xue Wu; Ying-Wei Yang

    2017-01-01

    Covalent organic frameworks (COFs) are an emerging class of porous covalent organic structures whose backbones were composed of light elements (B,C,N,O,Si) and linked by robust covalent bonds to endow such material with desirable properties,i.e.,inherent porosity,well-defined pore aperture,ordered channel structure,large surface area,high stability,and multi-dimension.As expected,the abovementioned properties of COFs broaden the applications of this class of materials in various fields such as gas storage and separation,catalysis,optoelectronics,sensing,small molecules adsorption,and drug delivery.In this review,we outlined the synthesis of COFs and highlighted their applications ranging from the initial gas storage and separation to drug delivery.

  2. On-surface synthesis of covalent coordination polymers on micrometer scale

    Institute of Scientific and Technical Information of China (English)

    Mathieu Koudia; Elena Nardi; Olivier Siri; Mathieu Abel

    2017-01-01

    On-surface synthesis under ultrahigh vacuum provides a promising strategy to control matter at the atomic level,with important implications for the design of new two-dimensional materials having remarkable electronic,magnetic,or catalytic properties.This strategy must address the problem of limited extension of the domains due to the irreversible nature of covalent bonds,which prevents the ripening of defects.We show here that extended materials can be produced by a controlled co-deposition process.In particular,co-deposition of quinoid zwitterion molecules with iron atoms on a Ag(111) surface held at 570 K allows the formation of micrometer-sized domains based on covalent coordination bonds.This work opens up the construction of micrometer-scale single-layer covalent coordination materials under vacuum conditions.

  3. Novel covalently linked insulin dimer engineered to investigate the function of insulin dimerization

    DEFF Research Database (Denmark)

    Vinther, Tine N.; Norrman, Mathias; Strauss, Holger M.

    2012-01-01

    An ingenious system evolved to facilitate insulin binding to the insulin receptor as a monomer and at the same time ensure sufficient stability of insulin during storage. Insulin dimer is the cornerstone of this system. Insulin dimer is relatively weak, which ensures dissociation into monomers...... in the circulation, and it is stabilized by hexamer formation in the presence of zinc ions during storage in the pancreatic ß-cell. Due to the transient nature of insulin dimer, direct investigation of this important form is inherently difficult. To address the relationship between insulin oligomerization...... and insulin stability and function, we engineered a covalently linked insulin dimer in which two monomers were linked by a disulfide bond. The structure of this covalent dimer was identical to the self-association dimer of human insulin. Importantly, this covalent dimer was capable of further oligomerization...

  4. Molecular Simulation Studies of Covalently and Ionically Grafted Nanoparticles

    Science.gov (United States)

    Hong, Bingbing

    Solvent-free covalently- or ionically-grafted nanoparticles (CGNs and IGNs) are a new class of organic-inorganic hybrid composite materials exhibiting fluid-like behaviors around room temperature. With similar structures to prior systems, e.g. nanocomposites, neutral or charged colloids, ionic liquids, etc, CGNs and IGNs inherit the functionality of inorganic nanopariticles, the facile processibility of polymers, as well as conductivity and nonvolatility from their constituent materials. In spite of the extensive prior experimental research having covered synthesis and measurements of thermal and dynamic properties, little progress in understanding of these new materials at the molecular level has been achieved, because of the lack of simulation work in this new area. Atomistic and coarse-grained molecular dynamics simulations have been performed in this thesis to investigate the thermodynamics, structure, and dynamics of these systems and to seek predictive methods predictable for their properties. Starting from poly(ethylene oxide) oligomers (PEO) melts, we established atomistic models based on united-atom representations of methylene. The Green-Kubo and Einstein-Helfand formulas were used to calculate the transport properties. The simulations generate densities, viscosities, diffusivities, in good agreement with experimental data. The chain-length dependence of the transport properties suggests that neither Rouse nor reptation models are applicable in the short-chain regime investigated. Coupled with thermodynamic integration methods, the models give good predictions of pressure-composition-density relations for CO 2 + PEO oligomers. Water effects on the Henry's constant of CO 2 in PEO have also been investigated. The dependence of the calculated Henry's constants on the weight percentage of water falls on a temperature-dependent master curve, irrespective of PEO chain length. CGNs are modeled by the inclusion of solid-sphere nanoparticles into the atomistic

  5. Merging constitutional and motional covalent dynamics in reversible imine formation and exchange processes.

    Science.gov (United States)

    Kovaříček, Petr; Lehn, Jean-Marie

    2012-06-06

    The formation and exchange processes of imines of salicylaldehyde, pyridine-2-carboxaldehyde, and benzaldehyde have been studied, showing that the former has features of particular interest for dynamic covalent chemistry, displaying high efficiency and fast rates. The monoimines formed with aliphatic α,ω-diamines display an internal exchange process of self-transimination type, inducing a local motion of either "stepping-in-place" or "single-step" type by bond interchange, whose rate decreases rapidly with the distance of the terminal amino groups. Control of the speed of the process over a wide range may be achieved by substituents, solvent composition, and temperature. These monoimines also undergo intermolecular exchange, thus merging motional and constitutional covalent behavior within the same molecule. With polyamines, the monoimines formed execute internal motions that have been characterized by extensive one-dimensional, two-dimensional, and EXSY proton NMR studies. In particular, with linear polyamines, nondirectional displacement occurs by shifting of the aldehyde residue along the polyamine chain serving as molecular track. Imines thus behave as simple prototypes of systems displaying relative motions of molecular moieties, a subject of high current interest in the investigation of synthetic and biological molecular motors. The motional processes described are of dynamic covalent nature and take place without change in molecular constitution. They thus represent a category of dynamic covalent motions, resulting from reversible covalent bond formation and dissociation. They extend dynamic covalent chemistry into the area of molecular motions. A major further step will be to achieve control of directionality. The results reported here for imines open wide perspectives, together with other chemical groups, for the implementation of such features in multifunctional molecules toward the design of molecular devices presenting a complex combination of

  6. Ego involvement increases doping likelihood.

    Science.gov (United States)

    Ring, Christopher; Kavussanu, Maria

    2018-08-01

    Achievement goal theory provides a framework to help understand how individuals behave in achievement contexts, such as sport. Evidence concerning the role of motivation in the decision to use banned performance enhancing substances (i.e., doping) is equivocal on this issue. The extant literature shows that dispositional goal orientation has been weakly and inconsistently associated with doping intention and use. It is possible that goal involvement, which describes the situational motivational state, is a stronger determinant of doping intention. Accordingly, the current study used an experimental design to examine the effects of goal involvement, manipulated using direct instructions and reflective writing, on doping likelihood in hypothetical situations in college athletes. The ego-involving goal increased doping likelihood compared to no goal and a task-involving goal. The present findings provide the first evidence that ego involvement can sway the decision to use doping to improve athletic performance.

  7. Genetic doping and health damages.

    Science.gov (United States)

    Fallahi, Aa; Ravasi, Aa; Farhud, Dd

    2011-01-01

    Use of genetic doping or gene transfer technology will be the newest and the lethal method of doping in future and have some unpleasant consequences for sports, athletes, and outcomes of competitions. The World Anti-Doping Agency (WADA) defines genetic doping as "the non-therapeutic use of genes, genetic elements, and/or cells that have the capacity to enhance athletic performance ". The purpose of this review is to consider genetic doping, health damages and risks of new genes if delivered in athletes. This review, which is carried out by reviewing relevant publications, is primarily based on the journals available in GOOGLE, ELSEVIER, PUBMED in fields of genetic technology, and health using a combination of keywords (e.g., genetic doping, genes, exercise, performance, athletes) until July 2010. There are several genes related to sport performance and if they are used, they will have health risks and sever damages such as cancer, autoimmunization, and heart attack.

  8. Combination of computational methods, adsorption isotherms and selectivity tests for the conception of a mixed non-covalent-semi-covalent molecularly imprinted polymer of vanillin.

    Science.gov (United States)

    Puzio, Kinga; Delépée, Raphaël; Vidal, Richard; Agrofoglio, Luigi A

    2013-08-06

    A novel molecularly imprinted polymer (MIP) for vanillin was prepared by photo initiated polymerization in dichloromethane using a mixed semi-covalent and non-covalent imprinting strategy. Taking polymerisable syringaldehyde as "dummy" template, acrylamide was chosen as functional monomer on B3LYP/6-31+G(d,p) density functional theory computational method basis with counterpoise. The binding parameters for the recognition of vanillin on imprinted polymers were studied with three different isotherm models (Langmuir, bi-Langmuir and Langmuir-Freundlich) and compared. The results indicate an heterogeneity of binding sites. It was found and proved by DFT calculations that the specific binding of vanillin in the cavities is due to non-covalent interactions of the template with the hydroxyphenyl- and the amide-moieties. The binding geometry of vanillin in the MIP cavity was also modelled. The obtained MIP is highly specific for vanillin (with an imprinting factor of 7.4) and was successfully applied to the extraction of vanillin from vanilla pods, red wine spike with vanillin, natural and artificial vanilla sugar with a recovery of 80%. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Doped Parton Distributions

    CERN Document Server

    Bertone, Valerio; Rojo, Juan

    2015-01-01

    Calculations of high-energy processes involving the production of b-quarks are typically performed in two different ways, the massive four-flavour scheme (4FS) and the massless five-flavour scheme (5FS). For processes where the combination of the 4FS and 5FS results into a matched calculation is technically difficult, it is possible to define a hybrid scheme known as the doped scheme, where above the b-quark threshold the strong coupling runs with $n_f=5$, as in the massless calculation, while the DGLAP splitting functions are those of the $n_f=4$ scheme. In this contribution we present NNPDF3.0 PDF sets in this doped scheme, compare them with the corresponding 4FS and 5FS sets, and discuss their relevance for LHC phenomenology.

  10. Preparation and fluorescent recognition properties for fluoride of a nanostructured covalently bonded europium hybrid material

    Institute of Scientific and Technical Information of China (English)

    余旭东; 李景印; 李亚娟; 耿丽君; 甄小丽; 于涛

    2015-01-01

    A novel covalently bonded Eu3+-based silica hybrid material was designed and its spectrophotometric anion sensing prop-erty was studied. The fluorescent receptor (europium complex) was covalently grafted to the silica matrix via a sol-gel approach. FTIR, UV-vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescent spectra were characterized, and the results revealed that the hybrid material with nanosphere structure displayed excellent photophysical property. In addition, the selective anion sensing property of the hybrid material was studied by UV-vis and fluorescence spectra. The results showed that the hybrid material exhibited a smart response with fluoride anions.

  11. Optical studies on Eu3+ doped boro-tellurite glasses

    Science.gov (United States)

    Maheshvaran, K.; Marimuthu, K.

    2012-06-01

    Eu3+ doped boro-tellurite glasses with the chemical composition (39-x)B2O3+30TeO2+15MgO+15K2O +xEu2O3 (where x = 0.01, 0.1, 1, 2 and 3 wt%) have been prepared by following conventional melt quenching technique. Spectroscopic properties of the Eu3+ doped boro-tellurite glasses have been studied by recording the optical absorption and luminescence measurements. Through the optical absorption spectra, bonding parameters (β¯, δ) have been calculated to identify the ionic/covalent nature of the glasses. Judd-Ofelt (JO) analysis have been carried out using the luminescence spectra. The JO parameters (Ωλ = 2, 4 and 6) were used to calculate the radiative properties for the 5D0 → 7FJ (J = 1, 2, 3 and 4) emission transitions of the Eu3+ ions. The change in optical properties with the variation of Eu3+ ion concentration have been studied and discussed with similar studies.

  12. [Doping and urologic tumors].

    Science.gov (United States)

    Pinto, F; Sacco, E; Volpe, A; Gardi, M; Totaro, A; Calarco, A; Racioppi, M; Gulino, G; D'Addessi, A; Bassi, P F

    2010-01-01

    Several substances such as growth hormone (GH), erythropoietin (Epo), and anabolic steroids (AS) are improperly utilized to increase the performance of athletes. Evaluating the potential cancer risk associated with doping agents is difficult since these drugs are often used at very high doses and in combination with other licit or illicit drugs. The GH, via its mediator, the insulin-like growth factor 1 (IGF-1), is involved in the development and progression of cancer. Animal studies suggested that high levels of GH/IGF-1 increase progression of androgen-independent prostate cancer. Clinical data regarding prostate cancer are mostly based on epidemiological studies or indirect data such as IGF-1 high levels in patients with prostate cancer. Even if experimental studies showed a correlation between Epo and cancer, no clinical data are currently available on cancer development related to Epo as a doping agent. Androgens are involved in prostate carcinogenesis modulating genes that regulate cell proliferation, apoptosis and angiogenesis. Most information on AS is anecdotal (case reports on prostate, kidney and testicular cancers). Prospective epidemiologic studies failed to support the hypothesis that circulating androgens are positively associated with prostate cancer risk. Currently, clinical and epidemiological studies supporting association between doping and urological neoplasias are not available. Nowadays, exposure to doping agents starts more prematurely with a consequent longer exposition period; drugs are often used at very high doses and in combination with other licit or illicit drugs. Due to all these elements it is impossible to predict all the side effects, including cancer; more detailed studies are therefore necessary.

  13. Doping and Public Health

    DEFF Research Database (Denmark)

    Christiansen, Ask Vest

    rad av världens främsta idrottsvetare och dopningsexperter hade mött upp för att presentera papers till en intresserad och engagerad publik. Temat för konferensen var "Doping and Public Health", och den aspekten behandlades också; dock tolkade flera presentatörer temat på sina egna vis, och hela...

  14. Neutron transmutation doping

    Energy Technology Data Exchange (ETDEWEB)

    Jun, Byung Jin

    2001-09-01

    HE OVERALL STATE OF THE ART RELATED WITH NEUTRON TRANSMUTATION DOPING(NCT) IS SURVEYED. ITEMS RELATED FOR THE REALIZATION OF NTD IN HANARO IS FOCUSED. IN ADDITION TO THE UNIFORM IRRADIATION AND ACHIEVING THE TARGET RESISTIVITY WHICH ARE THE MOST IMPORTANT TECHNICAL REQUIREMENTS FOR THE NTD, OTHER ITEMS SUCH AS THE FUNCTION AND ROLE OF NTD, MARKET TREND, QUALITY CONTROL ARE INCLUDED. MEANWHILE THE ONLY ADVANTAGE OF NTD IS ACHIEVING VERY HIGH UNIFORMITY OF DOPING, IT HAS SEVERAL DISADVANTAGES DUE TO THE USE OF NUCLEAR REACTOR. THEREFORE THE SEMICONDUCTOR INDUSTRY HAS CONTINUED DEVELOPMENT OF TECHNOLOGY TO REPLACE NTD, AND THE DEMAND OF NTD HAD BEEN DECREASED A LOT DURING 1990S. AS THE DEMAND FOR LARGE CRYSTAL INCREASES, HOWEVER, THE NTD DEMAND BEGAN TO INCREASE AGAIN FROM 2000. SINCE THE DEMAND FOR THE LARGER CRYSTAL WILL BE CONTINUED IN THE FUTURE, THE ROLE OF NTD WOULD BE NEEDED FOR THE LONGER TIME. IN ORDER TO MITIGATE THIS TREND OF DEMAND, THE REACTOR SHOULD BE CAPABLE OF ACCEPTING LARGE CRYSTAL AND THE EFFORT TO IMPROVE DOPING UNIFORMITY AND TO REDUCE THE COST SHOULD CONTINUED.

  15. Synthesis of Ag-doped hydrogenated carbon thin films by a hybrid ...

    Indian Academy of Sciences (India)

    Sci., Vol. 37, No. 7, December 2014, pp. 1669–1676. c Indian Academy of Sciences. Synthesis of ... PVD–PECVD deposition process ... Processing parameters (working pressure, .... prepared using the hydrocarbon ion beam without oper- .... Figure 5. Comparison of FTIR spectra obtained from the DLC and Ag-DLC thin.

  16. Doped biocompatible layers prepared by laser

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Miroslav; Weiserová, Marie; Kocourek, Tomáš; Jurek, Karel; Strnad, J.

    2010-01-01

    Roč. 20, č. 3 (2010), 562-567 ISSN 1054-660X R&D Projects: GA ČR GA204/07/0325 Grant - others:MPO(CZ) FI-IM5/218 Institutional research plan: CEZ:AV0Z10100522; CEZ:AV0Z50200510 Keywords : DLC * hydroxyapatite * in vivo * PLD * thin films Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.319, year: 2010

  17. Strong Depletion in Hybrid Perovskite p-n Junctions Induced by Local Electronic Doping.

    Science.gov (United States)

    Ou, Qingdong; Zhang, Yupeng; Wang, Ziyu; Yuwono, Jodie A; Wang, Rongbin; Dai, Zhigao; Li, Wei; Zheng, Changxi; Xu, Zai-Quan; Qi, Xiang; Duhm, Steffen; Medhekar, Nikhil V; Zhang, Han; Bao, Qiaoliang

    2018-04-01

    A semiconductor p-n junction typically has a doping-induced carrier depletion region, where the doping level positively correlates with the built-in potential and negatively correlates with the depletion layer width. In conventional bulk and atomically thin junctions, this correlation challenges the synergy of the internal field and its spatial extent in carrier generation/transport. Organic-inorganic hybrid perovskites, a class of crystalline ionic semiconductors, are promising alternatives because of their direct badgap, long diffusion length, and large dielectric constant. Here, strong depletion in a lateral p-n junction induced by local electronic doping at the surface of individual CH 3 NH 3 PbI 3 perovskite nanosheets is reported. Unlike conventional surface doping with a weak van der Waals adsorption, covalent bonding and hydrogen bonding between a MoO 3 dopant and the perovskite are theoretically predicted and experimentally verified. The strong hybridization-induced electronic coupling leads to an enhanced built-in electric field. The large electric permittivity arising from the ionic polarizability further contributes to the formation of an unusually broad depletion region up to 10 µm in the junction. Under visible optical excitation without electrical bias, the lateral diode demonstrates unprecedented photovoltaic conversion with an external quantum efficiency of 3.93% and a photodetection responsivity of 1.42 A W -1 . © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Dibenzothiophene adsorption at boron doped carbon nanoribbons studied within density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    López-Albarrán, P. [Facultad de Ingeniería en Tecnología de la Madera, Universidad Michoacana de San Nicolás de Hidalgo, Santiago Tapia 403, CP 58000, Morelia, Michoacán (Mexico); Navarro-Santos, P., E-mail: pnavarrosa@conacyt.mx [Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Santiago Tapia 403, CP 58000, Morelia, Michoacán (Mexico); Garcia-Ramirez, M. A. [Research Centre for Innovation in Aeronautical Engineering, Universidad Autónoma de Nuevo León, Ciudad Universitaria, San Nicolás de los Garza, CP 66451 Nuevo León (Mexico); Ricardo-Chávez, J. L. [Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055, Lomas 4" asección, CP 78216, San Luis Potosí, S. L. P. (Mexico)

    2015-06-21

    The adsorption of dibenzothiophene (DBT) on bare and boron-doped armchair carbon nanoribbons (ACNRs) is being investigated in the framework of the density functional theory by implementing periodic boundary conditions that include corrections from dispersion interactions. The reactivity of the ACNRs is characterized by using the Fukui functions as well as the electrostatic potential as local descriptors. Non-covalent adsorption mechanism is found when using the local Perdew-Becke-Ernzerhof functional, regardless of the DBT orientation and adsorption location. The dispersion interactions addition is a milestone to describe the adsorption process. The charge defects introduced in small number (i.e., by doping with B atoms), within the ACNRs increases the selectivity towards sulfur mainly due to the charge depletion at B sites. The DBT magnitude in the adsorption energy shows non-covalent interactions. As a consequence, the configurations where the DBT is adsorbed on a BC{sub 3} island increase the adsorption energy compared to random B arrangements. The stability of these configurations can be explained satisfactorily in terms of dipole interactions. Nevertheless, from the charge-density difference analysis and the weak Bader charge-distribution interactions cannot be ruled out completely. This is why the electronic properties of the ribbons are analyzed in order to elucidate the key role played by the B and DBT states in the adsorbed configurations.

  19. Covalent attachment of antagonists to the a7 nicotinic acetylcholine receptor: synthesis and reactivity of substituted maleimides

    DEFF Research Database (Denmark)

    Ambrus, Joseph I; Halliday, Jill I; Kanizaj, Nicholas

    2012-01-01

    The 3-methylmaleimide congeners of the natural product methyllycaconitine (MLA) and an analogue covalently attach to functional cysteine mutants of the a7 nicotinic acetylcholine receptor (nAChR).......The 3-methylmaleimide congeners of the natural product methyllycaconitine (MLA) and an analogue covalently attach to functional cysteine mutants of the a7 nicotinic acetylcholine receptor (nAChR)....

  20. Combination of supramolecular cross-linking with covalent cross-linking through epoxide ring-opening including gel studies

    NARCIS (Netherlands)

    Hofmeier, H.; El-Ghayoury, A.; Schubert, U.S.

    2003-01-01

    Terpolymers based on poly(methyl methacrylate), containing terpyridine-moieties as well as epoxide groups, were synthesized via free-radical polymeri-zation. The products were cross-linked non-covalently with iron(II) ions and cova-lently by treatment with AlCl3. Both steps could be combined in

  1. Combination of supramolecular cross-linking with covalent cross-linking through epoxide ring-opening including gel studies

    NARCIS (Netherlands)

    Hofmeier, H.; El-Ghayoury, A.; Schubert, U.S.

    2003-01-01

    Terpolymers based on poly(methyl methacrylate), containing terpyridinemoieties as well as epoxide groups, were synthesized via free-radical polymerization. The products were cross-linked non-covalently with iron(II) ions and covalently by treatment with AlCl3. Both steps could be combined in

  2. Novel covalently linked insulin dimer engineered to investigate the function of insulin dimerization.

    Directory of Open Access Journals (Sweden)

    Tine N Vinther

    Full Text Available An ingenious system evolved to facilitate insulin binding to the insulin receptor as a monomer and at the same time ensure sufficient stability of insulin during storage. Insulin dimer is the cornerstone of this system. Insulin dimer is relatively weak, which ensures dissociation into monomers in the circulation, and it is stabilized by hexamer formation in the presence of zinc ions during storage in the pancreatic β-cell. Due to the transient nature of insulin dimer, direct investigation of this important form is inherently difficult. To address the relationship between insulin oligomerization and insulin stability and function, we engineered a covalently linked insulin dimer in which two monomers were linked by a disulfide bond. The structure of this covalent dimer was identical to the self-association dimer of human insulin. Importantly, this covalent dimer was capable of further oligomerization to form the structural equivalent of the classical hexamer. The covalently linked dimer neither bound to the insulin receptor, nor induced a metabolic response in vitro. However, it was extremely thermodynamically stable and did not form amyloid fibrils when subjected to mechanical stress, underlining the importance of oligomerization for insulin stability.

  3. Immobilization of β-glucosidase onto mesoporous silica support: Physical adsorption and covalent binding of enzyme

    Directory of Open Access Journals (Sweden)

    Ivetić Darjana Ž.

    2014-01-01

    Full Text Available This paper investigates β-glucosidase immobilization onto mesoporous silica support by physical adsorption and covalent binding. The immobilization was carried out onto micro-size silica aggregates with the average pore size of 29 nm. During physical adsorption the highest yield of immobilized β-glucosidase was obtained at initial protein concentration of 0.9 mg ml-1. Addition of NaCl increased 1.7-fold, while Triton X-100 addition decreased 6-fold yield of adsorption in comparison to the one obtained without any addition. Covalently bonded β-glucosidase, via glutaraldehyde previously bonded to silanized silica, had higher yield of immobilized enzyme as well as higher activity and substrate affinity in comparison to the one physically adsorbed. Covalent binding did not considerably changed pH and temperature stability of obtained biocatalyst in range of values that are commonly used in reactions in comparison to unbounded enzyme. Furthermore, covalent binding provided biocatalyst which retained over 70% of its activity after 10 cycles of reuse. [Projekat Ministarstva nauke Republike Srbije, br. III 45021

  4. Assessing Covalency in Cerium and Uranium Hexachlorides: A Correlated Wavefunction and Density Functional Theory Study

    Directory of Open Access Journals (Sweden)

    Reece Beekmeyer

    2015-11-01

    Full Text Available The electronic structure of a series of uranium and cerium hexachlorides in a variety of oxidation states was evaluated at both the correlated wavefunction and density functional (DFT levels of theory. Following recent experimental observations of covalency in tetravalent cerium hexachlorides, bonding character was studied using topological and integrated analysis based on the quantum theory of atoms in molecules (QTAIM. This analysis revealed that M–Cl covalency was strongly dependent on oxidation state, with greater covalency found in higher oxidation state complexes. Comparison of M–Cl delocalisation indices revealed a discrepancy between correlated wavefunction and DFT-derived values. Decomposition of these delocalisation indices demonstrated that the origin of this discrepancy lay in ungerade contributions associated with the f-manifold which we suggest is due to self-interaction error inherent to DFT-based methods. By all measures used in this study, extremely similar levels of covalency between complexes of U and Ce in the same oxidation state was found.

  5. Mechanisms for Covalent Immobilization of Horseradish Peroxidase on Ion-Beam-Treated Polyethylene

    Directory of Open Access Journals (Sweden)

    Alexey V. Kondyurin

    2012-01-01

    Full Text Available The surface of polyethylene was modified by plasma immersion ion implantation. Structure changes including carbonization and oxidation were observed. High surface energy of the modified polyethylene was attributed to the presence of free radicals on the surface. The surface energy decay with storage time after treatment was explained by a decay of the free radical concentration while the concentration of oxygen-containing groups increased with storage time. Horseradish peroxidase was covalently attached onto the modified surface by the reaction with free radicals. Appropriate blocking agents can block this reaction. All aminoacid residues can take part in the covalent attachment process, providing a universal mechanism of attachment for all proteins. The native conformation of attached protein is retained due to hydrophilic interactions in the interface region. The enzymatic activity of covalently attached protein remained high. The long-term activity of the modified layer to attach protein is explained by stabilisation of unpaired electrons in sp2 carbon structures. A high concentration of free radicals can give multiple covalent bonds to the protein molecule and destroy the native conformation and with it the catalytic activity. The universal mechanism of protein attachment to free radicals could be extended to various methods of radiation damage of polymers.

  6. Protein tetrazinylation via diazonium coupling for covalent and catalyst-free bioconjugation.

    Science.gov (United States)

    Zhang, Jie; Men, Yuwen; Lv, Shanshan; Yi, Long; Chen, Jian-Feng

    2015-12-21

    An efficient and bench-stable reagent was synthesized for direct and covalent introduction of tetrazines onto target protein or virus surfaces, which can be further modified based on tetrazine-ene ligation to achieve fluorescence labelling or PEGylation under mild conditions.

  7. Covalent immobilization of redox protein within the mesopores of transparent conducting electrodes

    Czech Academy of Sciences Publication Activity Database

    Müller, V.; Rathouský, Jiří; Fattakhova-Rohlfing, D.

    2014-01-01

    Roč. 116, JAN 2014 (2014), s. 1-8 ISSN 0013-4686 R&D Projects: GA ČR GA104/08/0435 Institutional support: RVO:61388955 Keywords : Covalent immobilization * Porous electrodes * Redox proteins Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.504, year: 2014

  8. Recent advances in covalent, site-specific protein immobilization [version 1; referees

    DEFF Research Database (Denmark)

    Meldal, Morten Peter; Schoffelen, Sanne

    2016-01-01

    The properties of biosensors, biomedical implants, and other materials based on immobilized proteins greatly depend on the method employed to couple the protein molecules to their solid support. Covalent, site-specific immobilization strategies are robust and can provide the level of control...

  9. Identification of target cells by immunohistochemical detection of covalently rearranged estradiol in rehydrated paraffin sections.

    Science.gov (United States)

    Jungblut, P W; Sierralta, W D

    1998-04-01

    Estradiol is released from the binding niche of the receptor and covalently arrested in the molecular vicinity by the Mannich reaction during target fixation in acetic acid/formaldehyde. The exposed steroid is freely accessible for appropriate antibodies. It can be visualized in sections by the second antibody/enzyme technique in high resolution and without enhancements.

  10. Covalent functionalization of graphene oxide with polyglycerol and their use as templates for anchoring magnetic nanoparticles

    NARCIS (Netherlands)

    Pham, Tuan Anh; Kumar, Nanjundan Ashok; Jeong, Yeon Tae

    An efficient strategy for the preparation of water-dispersible hybrid material containing graphene oxide and polyglycerol for the first time is demonstrated. Pristine graphite was firstly oxidized to obtain graphene oxide with hydroxyl functional groups. Then, the covalent grafting of polyglycerol

  11. Direct covalent coupling of proteins to nanostructured plasma polymers: a route to tunable cell adhesion

    Czech Academy of Sciences Publication Activity Database

    Melnichuk, I.; Choukourov, A.; Bilek, M.; Weiss, A.; Vandrovcová, Marta; Bačáková, Lucie; Hanuš, J.; Kousal, J.; Shelemin, A.; Solař, P.; Slavínská, D.; Biederman, H.

    2015-01-01

    Roč. 351, Oct 1 (2015), s. 537-545 ISSN 0169-4332 R&D Projects: GA MZd(CZ) NT13297 Institutional support: RVO:67985823 Keywords : covalent binding * plasma polymers * MG-63 osteoblasts Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.150, year: 2015

  12. Formation of Me–O–Si covalent bonds at the interface between polysilazane and stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Amouzou, Dodji, E-mail: adodji@gmail.com [Research Centre in Physics of Matter and Radiation (PMR), University of Namur, Rue de Bruxelles 61, 5000 Namur (Belgium); Fourdrinier, Lionel; Maseri, Fabrizio [CRM-Group, Boulevard de Colonster, B 57, 4000 Liège (Belgium); Sporken, Robert [Research Centre in Physics of Matter and Radiation (PMR), University of Namur, Rue de Bruxelles 61, 5000 Namur (Belgium)

    2014-11-30

    Highlights: • Natural metal-oxides, hydroxides are detected on the top surface of steel substrates we tested. • Polysilazane reacts with hydroxide functional groups on steel substrates to form Cr–O–Si and Fe–O–Si covalent bonds. • Covalent bonding between steel and polysilazane at the interface was probed using spectroscopic techniques. - Abstract: In earlier works, we demonstrated the potential of polysilazane (PSZ) coatings for a use as insulating layers in Cu(In,Ga)Se{sub 2} (CIGS) solar cells prepared on steels substrates and showed a good adhesion between PSZ coatings and both AISI316 and AISI430 steels. In the present paper, spectroscopic techniques are used to elucidate the reason of such adhesion. X-ray Photoelectron Spectroscopy (XPS) was used to investigate surfaces for the two steel substrates and showed the presence of metal oxides and metal hydroxides at the top surface. XPS has been also used to probe interfaces between substrates and PSZ, and metallosiloxane (Me–O–Si) covalent bonds have been detected. These results were confirmed by Infra-Red Reflection Absorption Spectroscopy (IRRAS) analyses since vibrations related to Cr–O–Si and Fe–O–Si compounds were detected. Thus, the good adhesion between steel substrates and PSZ coatings was explained by covalent bonding through chemical reactions between PSZ precursors and hydroxide functional groups present on top surface of the two types of steel. Based on these results, an adhesion mechanism between steel substrates and PSZ coatings is proposed.

  13. Gel Electrolytes of Covalent Network Polybenzimidazole and Phosphoric Acid by Direct Casting

    DEFF Research Database (Denmark)

    Kirkebæk, Andreas; Aili, David; Henkensmeier, Dirk

    2017-01-01

    for preparing mechanically robust covalent network polybenzimidazole membranes containing up to 95 wt% phosphoric acid. Diamino-terminal pre-polymers of different chain lengths are first prepared, followed by addition of a trifunctional carboxylic acid. The crude solutions are cast and subsequently heat treated...

  14. Carbohydrate as covalent crosslink in human inter-alpha-trypsin inhibitor

    DEFF Research Database (Denmark)

    Jessen, T E; Faarvang, K L; Ploug, M

    1988-01-01

    The primary structure of inter-alpha-trypsin inhibitor is partially elucidated, but controversy about the construction of the polypeptide backbone still exists. We present evidence suggesting that inter-alpha-trypsin inhibitor represents a novel plasma protein structure with two separate polypept...... polypeptide chains covalently crosslinked only by carbohydrate (chondroitin sulphate)....

  15. A chiroptical switch based on supramolecular chirality transfer through alkyl chain entanglement and dynamic covalent bonding.

    Science.gov (United States)

    Lv, Kai; Qin, Long; Wang, Xiufeng; Zhang, Li; Liu, Minghua

    2013-12-14

    Chirality transfer is an interesting phenomenon in Nature, which represents an important step to understand the evolution of chiral bias and the amplification of the chirality. In this paper, we report the chirality transfer via the entanglement of the alkyl chains between chiral gelator molecules and achiral amphiphilic Schiff base. We have found that although an achiral Schiff base amphiphile could not form organogels in any kind of organic solvents, it formed co-organogels when mixed with a chiral gelator molecule. Interestingly, the chirality of the gelator molecules was transferred to the Schiff base chromophore in the mixed co-gels and there was a maximum mixing ratio for the chirality transfer. Furthermore, the supramolecular chirality was also produced based on a dynamic covalent chemistry of an imine formed by the reaction between an aldehyde and an amine. Such a covalent bond of imine was formed reversibly depending on the pH variation. When the covalent bond was formed the chirality transfer occurred, when it was destroyed, the transfer stopped. Thus, a supramolecular chiroptical switch is obtained based on supramolecular chirality transfer and dynamic covalent chemistry.

  16. Metal–organic covalent network chemical vapor deposition for gas separation

    NARCIS (Netherlands)

    Boscher, N.D.; Wang, M.; Perrotta, A.; Heinze, K.; Creatore, A.; Gleason, K.K.

    2016-01-01

    The chemical vapor deposition (CVD) polymerization of metalloporphyrin building units is demonstrated to provide an easily up-scalable one-step method toward the deposition of a new class of dense and defect-free metal–organic covalent network (MOCN) layers. The resulting hyper-thin and flexible

  17. Covalent binding of organophosphorothioates to albumin: A new perspective for OP-pesticide biomonitoring?

    NARCIS (Netherlands)

    Noort, D.; Hulst, A.G.; Zuylen, A. van; Rijssel, E. van; Schans, M.J. van der

    2009-01-01

    We here report on the covalent binding of various organophosphorothioate (OPT) pesticides to albumin at in vitro exposure levels that did not give rise to butyrylcholinesterase inhibition. Adduct formation occurred at the Tyr-411 residue of albumin, as was firmly corroborated by LC-tandem MS

  18. Stabilization of 5A1 urease by covalent attachement to wool | Ahmed ...

    African Journals Online (AJOL)

    The investigation of five bacterial strains for urease production referred that Bacillus licheniformis 5A1 had the highest urease activity (10.3U/ml/min) after 24h. The enzyme was covalently coupled to different carriers via glutaraldehyde, and wool gave the highest immobilization yield (76.4%) and retained 85% of the original ...

  19. Origin of the Distinct Diffusion Behaviors of Cu and Ag in Covalent and Ionic Semiconductors.

    Science.gov (United States)

    Deng, Hui-Xiong; Luo, Jun-Wei; Li, Shu-Shen; Wei, Su-Huai

    2016-10-14

    It is well known that Cu diffuses faster than Ag in covalent semiconductors such as Si, which has prevented the replacement of Ag by Cu as a contact material in Si solar cells for reducing the cost. Surprisingly, in more ionic materials such as CdTe, Ag diffuses faster than Cu despite that it is larger than Cu, which has prevented the replacement of Cu by Ag in CdTe solar cells to improve the performance. But, so far, the mechanisms behind these distinct diffusion behaviors of Cu and Ag in covalent and ionic semiconductors have not been addressed. Here we reveal the underlying mechanisms by combining the first-principles calculations and group theory analysis. We find that the symmetry controlled s-d coupling plays a critical role in determining the diffusion behaviors. The s-d coupling is absent in pure covalent semiconductors but increases with the ionicity of the zinc blende semiconductors, and is larger for Cu than for Ag, owing to its higher d orbital energy. In conjunction with Coulomb interaction and strain energy, the s-d coupling is able to explain all the diffusion behaviors from Cu to Ag and from covalent to ionic hosts. This in-depth understanding enables us to engineer the diffusion of impurities in various semiconductors.

  20. Discovery of covalent inhibitors for MIF tautomerase via cocrystal structures with phantom hits from virtual screening

    Energy Technology Data Exchange (ETDEWEB)

    McLean, Larry R.; Zhang, Ying; Li, Hua; Li, Ziyu; Lukasczyk, Ulrike; Choi, Yong-Mi; Han, Zuoning; Prisco, Joy; Fordham, Jeremy; Tsay, Joseph T.; Reiling, Stephan; Vaz, Roy J.; Li, Yi; (Sanofi)

    2010-10-28

    Biochemical and X-ray crystallographic studies confirmed that hydroxyquinoline derivatives identified by virtual screening were actually covalent inhibitors of the MIF tautomerase. Adducts were formed by N-alkylation of the Pro-1 at the catalytic site with a loss of an amino group of the inhibitor.

  1. Dynamic covalent chemistry of bisimines at the solid/liquid interface monitored by scanning tunnelling microscopy.

    Science.gov (United States)

    Ciesielski, Artur; El Garah, Mohamed; Haar, Sébastien; Kovaříček, Petr; Lehn, Jean-Marie; Samorì, Paolo

    2014-11-01

    Dynamic covalent chemistry relies on the formation of reversible covalent bonds under thermodynamic control to generate dynamic combinatorial libraries. It provides access to numerous types of complex functional architectures, and thereby targets several technologically relevant applications, such as in drug discovery, (bio)sensing and dynamic materials. In liquid media it was proved that by taking advantage of the reversible nature of the bond formation it is possible to combine the error-correction capacity of supramolecular chemistry with the robustness of covalent bonding to generate adaptive systems. Here we show that double imine formation between 4-(hexadecyloxy)benzaldehyde and different α,ω-diamines as well as reversible bistransimination reactions can be achieved at the solid/liquid interface, as monitored on the submolecular scale by in situ scanning tunnelling microscopy imaging. Our modular approach enables the structurally controlled reversible incorporation of various molecular components to form sophisticated covalent architectures, which opens up perspectives towards responsive multicomponent two-dimensional materials and devices.

  2. Regio- and Stereospecific Conversion of 4-Alkylphenols by the Covalent Flavoprotein Vanillyl-Alcohol Oxidase

    NARCIS (Netherlands)

    Heuvel, Robert H.H. van den; Fraaije, Marco W.; Laane, Colja; Berkel, Willem J.H. van

    1998-01-01

    The regio- and stereospecific conversion of prochiral 4-alkylphenols by the covalent flavoprotein vanillyl-alcohol oxidase was investigated. The enzyme was active, with 4-alkylphenols bearing aliphatic side chains of up to seven carbon atoms. Optimal catalytic efficiency occurred with 4-ethylphenol

  3. The yeast cell fusion protein Prm1p requires covalent dimerization to promote membrane fusion.

    Directory of Open Access Journals (Sweden)

    Alex Engel

    2010-05-01

    Full Text Available Prm1p is a multipass membrane protein that promotes plasma membrane fusion during yeast mating. The mechanism by which Prm1p and other putative regulators of developmentally controlled cell-cell fusion events facilitate membrane fusion has remained largely elusive. Here, we report that Prm1p forms covalently linked homodimers. Covalent Prm1p dimer formation occurs via intermolecular disulfide bonds of two cysteines, Cys-120 and Cys-545. PRM1 mutants in which these cysteines have been substituted are fusion defective. These PRM1 mutants are normally expressed, retain homotypic interaction and can traffic to the fusion zone. Because prm1-C120S and prm1-C545S mutants can form covalent dimers when coexpressed with wild-type PRM1, an intermolecular C120-C545 disulfide linkage is inferred. Cys-120 is adjacent to a highly conserved hydrophobic domain. Mutation of a charged residue within this hydrophobic domain abrogates formation of covalent dimers, trafficking to the fusion zone, and fusion-promoting activity. The importance of intermolecular disulfide bonding informs models regarding the mechanism of Prm1-mediated cell-cell fusion.

  4. COVALENTLY ATTACHED MULTILAYER ULTRA-THIN FILMS FROM DIAZORESIN AND CALIXARENES

    Institute of Scientific and Technical Information of China (English)

    Zhao-hui Yang; Wei-xiao Cao

    2003-01-01

    A kind of photosensitive ultra-thin film was fabricated from diazoresin (DR) and various calixarenes by using the self-assembly technique. Under UV irradiation both the ionic- and hydrogen bonds between the layers of the film will convert into covalent bonds. As a result, the stability of the film toward polar solvents increases dramatically.

  5. Covalent Bonding of Chlorogenic Acid Induces Structural Modifications on Sunflower Proteins

    NARCIS (Netherlands)

    Karefyllakis, D.; Salakou, Stavroula; Bitter, J.H.; Goot, van der A.J.; Nikiforidis, K.

    2018-01-01

    Proteins and phenols coexist in the confined space of plant cells leading to reactions between them, which result in new covalently bonded complex molecules. This kind of reactions has been widely observed during storage and processing of plant materials. However, the nature of the new complex

  6. Molecular-dynamics simulation of crystalline 18-crown-6: thermal shortening of covalent bonds

    NARCIS (Netherlands)

    van Eerden, J.; Harkema, Sybolt; Feil, D.

    1990-01-01

    Molecular-dynamics simulations of crystalline 18-crown-6 have been performed in a study of the apparent thermal shortening of covalent bonds observed in crystal structures. At 100 K, a shortening of 0.006 _+ 0.001 A for C----C and C----O bonds was obtained. This result was found to be independent of

  7. A simple approach for immobilization of gold nanoparticles on graphene oxide sheets by covalent bonding

    NARCIS (Netherlands)

    Pham, Tuan Anh; Choi, Byung Choon; Lim, Kwon Taek; Jeong, Yeon Tae

    2011-01-01

    Amino - functionalized gold nanoparticles with a diameter of around 5 nm were immobilized onto the surface of graphene oxide sheets (GOS) by covalent bonding through a simple amidation reaction. Pristine graphite was firstly oxidized and exfoliated to obtain GOS, which further were acylated with

  8. 共价键的离子化%Ionization of Covalent Bond

    Institute of Scientific and Technical Information of China (English)

    王稼国; 荆西平

    2017-01-01

    本文用化学键理论分析和推导了共价键离子化的几种方式,包括金属和非金属单质中共价键的诱导离子化、化合物中共价键的降温和自诱导离子化以及含氢化合物和金属化合物的诱导离子化.从能量角度分析了离子化趋势的规律性,并且讨论了共价键的离子化的一些重要应用.%Several ionization patterns of covalent bond,including induced-ionization of covalent bond in metals and nonmetals,induced-ionization of covalent bond in hydrogen compounds and metal compounds,lowering temperature and self-induced ionization of compound,and so on,were dedueed and analyzed by using chemical bond theory.The trend of ionization was also analyzed on energy changing and several important applications of the ionization of covalent bond were discussed.

  9. Ultrafast cooling by covalently bonded graphene-carbon nanotube hybrid immersed in water

    DEFF Research Database (Denmark)

    Chen, Jie; Walther, Jens Honore; Koumoutsakos, Petros

    2016-01-01

    , we demonstrate, through transient heat-dissipation simulations, that a covalently bonded graphene-carbon nanotube (G-CNT) hybrid immersed in water is a promising solution for the ultrafast cooling of such high-temperature and high heat-flux surfaces. The G-CNT hybrid offers a unique platform...

  10. Nano-Sized Zero Valent Iron and Covalent Organic Polymer Composites for Azo Dye Remediation

    DEFF Research Database (Denmark)

    Mines, Paul D.; Byun, Jeehye; Hwang, Yuhoon

    2014-01-01

    . In this study, the effect of various covalent organic polymers (COPs) as effective supporting materials for nZVI for optimal pollutant degradation was assessed. These COPs demonstrate promising results for the ability to adsorb and remove carbon dioxide, yielding the notion that they are capable of groundwater...... in chlorinated organics, heavy metals, and various other groundwater contaminants....

  11. Catalyst recycling via specific non-covalent adsorption on modified silicas

    NARCIS (Netherlands)

    Kluwer, A.M.; Simons, C.; Knijnenburg, Q.; van der Vlugt, J.I.; de Bruin, B.; Reek, J.N.H.

    2013-01-01

    This article describes a new strategy for the recycling of a homogeneous hydroformylation catalyst, by selective adsorption of the catalyst to tailor-made supports after a batchwise reaction. The separation of the catalyst from the product mixture is based on selective non-covalent supramolecular

  12. Covalent binding of nitrogen mustards to the cysteine-34 residue in human serum albumin

    NARCIS (Netherlands)

    Noort, D.; Hulst, A.G.; Jansen, R.

    2002-01-01

    Covalent binding of various clinically important nitrogen mustards to the cysteine-34 residue of human serum albumin, in vitro and in vivo, is demonstrated. A rapid method for detection of these adducts is presented, based on liquid chromatography-tandem mass spectrometry analysis of the adducted

  13. Nature and consequences of non-covalent interactions between flavonoids and macronutrients in foods.

    Science.gov (United States)

    Bordenave, Nicolas; Hamaker, Bruce R; Ferruzzi, Mario G

    2014-01-01

    Many of the potential health benefits of flavonoids have been associated with their specific chemical and biological properties including their ability to interact and bind non-covalently to macronutrients in foods. While flavonoid-protein interactions and binding have been the subject of intensive study, significantly less is understood about non-covalent interactions with carbohydrates and lipids. These interactions with macronutrients are likely to impact both the flavonoid properties in foods, such as their radical scavenging activity, and the food or beverage matrix itself, including their taste, texture and other sensorial properties. Overall, non-covalent binding of flavonoids with macronutrients is primarily driven by van der Waals interactions. From the flavonoid perspective, these interactions are modulated by characteristics such as degree of polymerization, molecular flexibility, number of external hydroxyl groups, or number of terminal galloyl groups. From the macronutrient standpoint, electrostatic and ionic interactions are generally predominant with carbohydrates, while hydrophobic interactions are generally predominant with lipids and mainly limited to interactions with flavonols. All of these interactions are involved in flavonoid-protein interactions. While primarily associated with undesirable characteristics in foods and beverages, such as astringency, negative impact on macronutrient digestibility and hazing, more recent efforts have attempted to leverage these interactions to develop controlled delivery systems or strategies to enhance flavonoids bioavailability. This paper aims at reviewing the fundamental bases for non-covalent interactions, their occurrence in food and beverage systems and their impact on the physico-chemical, organoleptic and some nutritional properties of food.

  14. Improved Performance of Pseudomonas fluorescens lipase by covalent immobilization onto Amberzyme

    NARCIS (Netherlands)

    Aslan, Yakup; Handayani, Nurrahmi; Stavila, Erythrina; Loos, Katja

    2013-01-01

    Objective: In this study, the conditions of covalent immobilization of Pseudomonas fluorescens lipase onto an oxirane-activated support (Amberzyme) were optimized to obtain a high activity yield. Furthermore, the operational and storage stabilities of immobilized lipase were tested. Methods: Optimum

  15. Inorganic Materials as Supports for Covalent Enzyme Immobilization: Methods and Mechanisms

    Directory of Open Access Journals (Sweden)

    Paolo Zucca

    2014-09-01

    Full Text Available Several inorganic materials are potentially suitable for enzymatic covalent immobilization, by means of several different techniques. Such materials must meet stringent criteria to be suitable as solid matrices: complete insolubility in water, reasonable mechanical strength and chemical resistance under the operational conditions, the capability to form manageable particles with high surface area, reactivity towards derivatizing/functionalizing agents. Non-specific protein adsorption should be always considered when planning covalent immobilization on inorganic solids. A huge mass of experimental work has shown that silica, silicates, borosilicates and aluminosilicates, alumina, titania, and other oxides, are the materials of choice when attempting enzyme immobilizations on inorganic supports. More recently, some forms of elemental carbon, silicon, and certain metals have been also proposed for certain applications. With regard to the derivatization/functionalization techniques, the use of organosilanes through silanization is undoubtedly the most studied and the most applied, although inorganic bridge formation and acylation with selected acyl halides have been deeply studied. In the present article, the most common inorganic supports for covalent immobilization of the enzymes are reviewed, with particular focus on their advantages and disadvantages in terms of enzyme loadings, operational stability, undesired adsorption, and costs. Mechanisms and methods for covalent immobilization are also discussed, focusing on the most widespread activating approaches (such as glutaraldehyde, cyanogen bromide, divinylsulfone, carbodiimides, carbonyldiimidazole, sulfonyl chlorides, chlorocarbonates, N-hydroxysuccinimides.

  16. A Cost-Effective Physical Modeling Exercise to Develop Students' Understanding of Covalent Bonding

    Science.gov (United States)

    Turner, Kristy L.

    2016-01-01

    Chemical bonding is one of the basic concepts in chemistry, and the topic of covalent bonding forms an important core of knowledge for the high school chemistry student. For many teachers it is a challenging concept to teach, not least because it relies mainly on traditional instruction and written work. Similarly, many students find the topic…

  17. Covalently Cross-Linked Sulfone Polybenzimidazole Membranes with Poly(Vinylbenzyl Chloride) for Fuel Cell Applications

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Aili, David; Li, Qingfeng

    2013-01-01

    Covalently cross-linked polymer membranes were fabricated from poly(aryl sulfone benzimidazole) (SO(2) PBI) and poly(vinylbenzyl chloride) (PVBCl) as electrolytes for high-temperature proton-exchange-membrane fuel cells. The cross-linking imparted organo insolubility and chemical stability against...

  18. Crystallization characteristics of Mg-doped Ge2Sb2Te5 films for phase change memory applications

    International Nuclear Information System (INIS)

    Fu Jing; Shen Xiang; Nie Qiuhua; Wang Guoxiang; Wu Liangcai; Dai Shixun; Xu Tiefeng; Wang, R.P.

    2013-01-01

    Highlights: ► Mg-doped Ge 2 Sb 2 Te 5 (GST) phase change films with higher resistance and better thermal stability have been proposed. ► The increase of Mg content result in an enhancement in crystallization temperature, activation energy and electrical resistance. ► The proper Mg addition in GST can lead to a one-step crystallization process from amorphous to faced-centered cubic (fcc) phase. ► The formation of covalent Mg-Sb and Mg-Te bonds contribute to the enhancement thermal stability in Mg-doped GST films. - Abstract: Mg-doped Ge 2 Sb 2 Te 5 (GST) films with different Mg doping concentrations have been prepared, and their crystallization behavior, structure and electrical properties have been systematically investigated for phase-change memory applications. The results show that the addition of Mg into GST films could result in an enhancement in crystallization temperature, activation energy and electrical resistance compared with the conventional GST films, indicating that a good amorphous thermal stability. On the other hand, the proper Mg concentration ranging from 13.6 to 31.1 at.% can lead to a one-step crystallization process from amorphous to faced-centered cubic (fcc) phase and suppress the formation of the hexagonal close-packed (hcp) crystalline phase. X-ray photoelectron spectra (XPS) further confirm that the formation of covalent Mg-Sb and Mg-Te bonds contribute to the enhanced thermal stability in Mg-doped GST films.

  19. Reversible and formaldehyde-mediated covalent binding of a bis-amino mitoxantrone analogue to DNA.

    Science.gov (United States)

    Konda, Shyam K; Kelso, Celine; Pumuye, Paul P; Medan, Jelena; Sleebs, Brad E; Cutts, Suzanne M; Phillips, Don R; Collins, J Grant

    2016-05-18

    The ability of a bis-amino mitoxantrone anticancer drug (named WEHI-150) to form covalent adducts with DNA, after activation by formaldehyde, has been studied by electrospray ionisation mass spectrometry and HPLC. Mass spectrometry results showed that WEHI-150 could form covalent adducts with d(ACGCGCGT)2 that contained one, two or three covalent links to the octanucleotide, whereas the control drugs (daunorubicin and the anthracenediones mitoxantrone and pixantrone) only formed adducts with one covalent link to the octanucleotide. HPLC was used to examine the extent of covalent bond formation of WEHI-150 with d(CGCGCG)2 and d(CG(5Me)CGCG)2. Incubation of WEHI-150 with d(CG(5Me)CGCG)2 in the presence of formaldehyde resulted in the formation of significantly greater amounts of covalent adducts than was observed with d(CGCGCG)2. In order to understand the observed increase of covalent adducts with d(CG(5Me)CGCG)2, an NMR study of the reversible interaction of WEHI-150 at both CpG and (5Me)CpG sites was undertaken. Intermolecular NOEs were observed in the NOESY spectra of d(ACGGCCGT)2 with added WEHI-150 that indicated that the drug selectively intercalated at the CpG sites and from the major groove. In particular, NOEs were observed from the WEHI-150 H2,3 protons to the H1' protons of G3 and G7 and from the H6,7 protons to the H5 protons of C2 and C6. By contrast, intermolecular NOEs were observed between the WEHI-150 H2,3 protons to the H2'' proton of the (5Me)C3 in d(CG(5Me)CGCG)2, and between the drug aliphatic protons and the H1' proton of G4. This demonstrated that WEHI-150 preferentially intercalates at (5Me)CpG sites, compared to CpG sequences, and predominantly via the minor groove at the (5Me)CpG site. The results of this study demonstrate that WEHI-150 is likely to form interstrand DNA cross-links, upon activation by formaldehyde, and consequently exhibit greater cytotoxicity than other current anthracenedione drugs.

  20. Neutron transmutation doped Ge bolometers

    Science.gov (United States)

    Haller, E. E.; Kreysa, E.; Palaio, N. P.; Richards, P. L.; Rodder, M.

    1983-01-01

    Some conclusions reached are as follow. Neutron Transmutation Doping (NTD) of high quality Ge single crystals provides perfect control of doping concentration and uniformity. The resistivity can be tailored to any given bolometer operating temperature down to 0.1 K and probably lower. The excellent uniformity is advantaged for detector array development.