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  • 1.
    Abel, Martin
    et al.
    University of Texas, Physics Department.
    Frommhold, Lothar
    University of Texas, Physics Department.
    Gustafsson, Magnus
    Department of Chemistry, University of Gothenburg.
    Collision-induced absorption at wavelengths near 5 μm by dense hydrogen gas2009Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 131, nr 18, artikel-id 181102Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Based on a recent ab initiointeraction-induced dipole surface of collisionally interacting molecular hydrogen pairs H2–H2, we compute the binary absorption coefficients at wavelengths near 5 μm at temperatures of 77.5 and 297 K for comparison with existing laboratory measurements. We observe satisfactory agreement of the measurements with our calculations, thereby concluding an earlier study [Gustafsson et al., J. Chem. Phys.119, 12264 (2003)], which was based on an ab initiointeraction-induced dipole surface that was inadequate for the 5 μm band.

  • 2.
    Abel, Martin
    et al.
    University of Texas, Physics Department.
    Frommhold, Lothar
    University of Texas, Physics Department.
    Wang, Fei
    Physics Department, Beijing Institute of Technology, China, University of Texas, Physics Department.
    Gustafsson, Magnus
    Department of Chemistry, University of Gothenburg.
    Li, Xiaoping
    Department of Chemistry, Michigan State University.
    Hunt, Katherine L.C.
    Department of Chemistry, Michigan State University, East Lansing, Department of Chemistry, Michigan State University.
    Collision-induced absorption by supermolecular complexes from a new potential energy and induced dipole surface, suited for calculations up to thousands of kelvin2010Ingår i: 20th International Conference on Spectral Line Shapes: St. John's, Newfoundland, Canada, 6 - 11 June 2010 ; [20th ICSLS] / [ed] John K.C. Lewis; Adriana Predoi-Cross, Melville, NY: American Institute of Physics (AIP), 2010, s. 251-257Konferensbidrag (Refereegranskat)
    Abstract [en]

    Absorption by pairs of H2 molecules is an important opacity source in the atmospheres of the outer planets, and thus of special astronomical interest. The emission spectra of cool white dwarf stars differ significantly from the expected blackbody spectra, amongst other reasons due to absorption by H2-H2, H2-He, and H2-H collisional complexes in the stellar atmospheres. To model the radiative processes in these atmospheres, which have temperatures of several thousand kelvin, one needs accurate knowledge of the induced dipole (ID) and potential energy surfaces (PES) of such collisional complexes. These come from quantum-chemical calculations with the H2 bonds stretched or compressed far from equilibrium. Laboratory measurements of collision-induced (CI) absorption exist only at much lower temperature. For H2 pairs at room temperature, the calculated spectra of the rototranslational band, the fundamental band, and the first overtone match the experimental data very well. In addition, with the newly obtained IDS it became possible to reproduce the measurements in the far blue wing of the rototranslational spectrum of H2 at 77.5 K, as well as at 300 K. Similarly good agreement between theory and measurement is seen in the fundamental band of molecular deuterium at room temperature. Furthermore, we also show the calculated absorption spectra of H2-He at 600 K and of H2-H2 at 2,000 K, for which there are no experimental data for comparison

  • 3.
    Afanasiev, Sergey V.
    et al.
    Joint Institute for Nuclear Research Joliot-Curie 6.
    Afonin, Alexander G.
    Institute of High Energy Physics - Moscow Region.
    Ambrosi, Giovanni
    INFN Sezione di Perugia.
    Azzarello, Philipp
    INFN Sezione di Perugia.
    Baranov, Vladimir T.
    Institute of High Energy Physics - Moscow Region.
    Baricordi, Stefano
    INFN Sezione di Ferrara.
    Battiston, Roberto
    INFN Sezione di Perugia.
    Bertucci, Bruna
    INFN Sezione di Perugia.
    Bolognini, Davide
    Università dell'Insubria.
    Burger, William J.
    INFN Sezione di Perugia.
    Carnera, Alberto
    INFN Laboratori Nazionali di Legnaro.
    Cavoto, Gianluca
    INFN Sezione di Roma.
    Chesnokov, Yury A.
    Institute of High Energy Physics - Moscow Region.
    Dalpiaz, Pietro
    INFN Sezione di Ferrara.
    Mea, Gianantonio Della
    INFN Laboratori Nazionali di Legnaro.
    Denisov, Alexander S.
    Petersburg Nuclear Physics Institute.
    Salvador, Davide De
    INFN Laboratori Nazionali di Legnaro.
    Fiorini, Massimiliano
    INFN Sezione di Ferrara.
    Foggetta, Luca
    Università dell'Insubria.
    Gavrikov, Yury A.
    Petersburg Nuclear Physics Institute.
    Guidi, Vincenzo
    INFN Sezione di Ferrara.
    Hasan, Said
    Università dell'Insubria.
    Ionica, Maria
    INFN Sezione di Perugia.
    Ivanov, Yuri M.
    Petersburg Nuclear Physics Institute.
    Ivochkin, Vladimir G.
    Petersburg Nuclear Physics Institute.
    Vomiero, Alberto
    INFN Laboratori Nazionali di Legnaro.
    Zuccon, Paolo
    INFN Sezione di Perugia.
    Experimental apparatus to study crystal channeling in an external SPS beamline2007Ingår i: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 6634Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For the new generation of high intensity hadronic machines as, for instance, LHC, halo collimation is a necessary issue for the accelerator to operate at the highest possible luminosity and to prevent the damage of superconductor magnets.1 We propose an experiment aimed to systematic study of the channeling phenomenology and of the newly observed "volume reflection" effect. This experiment will be performed for an external SPS beamline and will make use of a primary proton beam with 400 GeV/c momentum and very small (∼ 3 μrad) divergence. The advantage of a proposed experiment is precise tracking of particles that interacted with a crystal, so that to determine the single-pass efficiency for all the processes involved. For this purpose, a telescope equipped with high-resolution silicon microstrip detectors will be used. New generation silicon crystals and an extra-precise goniometer are mandatory issues. Main goal of the experiment is to get the precise information on channeling of relativistic particles and, ultimately, on the feasibility of such technique for halo collimation at LHC. In this contribution we review the status of the setting-up of experimental apparatus and its future development in sight of the planned run in September 2006.

  • 4.
    Aftab, A.
    et al.
    Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia.
    Ismail, Abdul Razak
    Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia.
    Ibupoto, Zafar
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Akeiber, Hussein J.
    Faculty of Mechanical Engineering, Universiti Teknologi Malaysia.
    Malghani, M.G.K.
    Department of Environmental Management and Policy, BUITEMS Quetta, Pakistan.
    Nanoparticles based drilling muds a solution to drill elevated temperature wells: a review2017Ingår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 76, s. 1301-1313Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Demand of the oil and gas energy is increasing very drastically. Conventional hydrocarbon reservoirs contain below the sealing cap rock (shale) and easily move towards wellbore are at the depletion stage. Therefore, drilling engineers in collaboration with mud engineers, geologists and geophysicists are looking for innovative materials to drill unconventional hydrocarbons reservoir which are distributed at the basin scale and cannot approach easily. Geo-thermal energy wells and most of unconventional reservoirs are occurred at high pressure high temperature (HPHT) conditions. Conventional micro-macro organic drilling mud additives with heat insulator in nature can minimize efficiency while drilling HPHT wells. Oil-based muds (OBM) are strictly restricted due to high toxic level and poor emulsion stability at HT. However, this review suggests that addition of macro size organic particles and inorganic nanoparticles can enhance rheological performance, reduce filtrate loss volume and improve shale inhibition characteristics of environmental friendly water-based mud (WBM). Despite an impressive amount of experimental work has been done over drilling additives and their effect over rheological and shale inhibition, taking into account their literature review are rare. In addition, there is no review work of the knowledge gained to date. This work will hope fully trigger further development and new research topics in the area of drilling muds system.

  • 5.
    Ahdikari, Rajesh
    et al.
    Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel-Boulet, Varennes.
    Jin, Lei
    Institut National de la Recherche Scientifique Energie Varennes.
    Pardo, Fabola Navarro
    Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, Varennes.
    Benetti, Daniele
    INRS, Quebec University, Varennes, Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, Varennes.
    Otabi, Bandar Al
    Department of Electrical and Computer Engineering, McGill University, Montreal.
    Vanka, Srinivas
    Department of Electrical and Computer Engineering, McGill University, Montreal.
    Zhao, Haiguang
    Institut National de la Recherche Scientifique Energie Varennes, INRS Centre for Energy, Materials and Telecommunications, CNR-INO SENSOR Lab, Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel-Boulet, Varennes.
    Mi, Zetian
    Department of Electrical and Computer Engineering, McGill University, Montreal.
    Vomiero, Alberto
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Rosei, Frederico
    Institut National de la Recherche Scientifique Energie Varennes, Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel-Boulet, Varennes.
    High Efficiency, Pt-free Photoelectrochemical Cells for Solar Hydrogen Generation based on “Giant” Quantum Dots2016Ingår i: Nano Energy, ISSN 2211-2855, Vol. 27, s. 265-274Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quantum dot (QD) sensitized TiO2 is considered as a highly promising photoanode material for photoelectrochemical (PEC) solar hydrogen production. However, due to its limited stability, the photoanode suffers from degradation of its long-term PEC performance. Here, we report the design and characterization of a high-efficiency and long-term stable Pt-free PEC cell. The photoanode is composed of a mesoporous TiO2 nanoparticle film sensitized with “giant” core@shell QDs for PEC solar hydrogen generation. The thick shell enhances light absorption in the visible range, increases the stability of the QDs and does not inhibit charge separation, injection and transport, needed for proper operation of the device. We prepared thin films of Cu2S nanoflakes through a simple and reproducible procedure, and used them as counter-electrodes replacing the standard Pt film, resulting in equivalent performances of the PEC cell. We obtained an unprecedented photocurrent density (~10 mA/cm2) for “giant” QDs based PEC devices (and corresponding H2 generation) and a very promising stability, indicating that the proposed cell architecture is a good candidate for long-term stable QD-based PEC solar hydrogen generation.

  • 6. Aksenova, N.A.
    et al.
    Isakina, A.P.
    Prokhvatilov, A.N.
    Strzhemechny, M.A.
    Soldatov, Alexander
    Sundqvist, Bertil
    Structural studies of C60 polymerized at high pressure1997Ingår i: Proceedings of the Symposium on Recent Advances in the Chemistry and Physics of Fullerenes and Related Materials: : [based on papers presented at the fourth symposium of the Fullerenes Group of the Electrochemical Society, held at the 192nd Meeting of the Electrochemical Society in Paris, France, from August 31 to September 5, 1997. This symposium, entitled Fullerenes: Chemistry, Physics and New Directions X ...] / [ed] Karl M. Kadish, Pennington, NJ: Electrochemical Society, Incorporated , 1997Konferensbidrag (Refereegranskat)
  • 7. Aleksandrovski, A. N.
    et al.
    Kir'yanova, E. A.
    Manzheli, V. G.
    Soldatov, Alexander
    Tolkachev, A. M.
    Anomalies of the plastic deformation of solid parahydrogen1987Ingår i: Soviet Journal of Low Temperature Physics, ISSN 0360-0335, Vol. 13, nr 10, s. 623-624Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The work hardening curves σ(ε) of special-purity parahydrogen single crystals are obtained in the temperature range 2-6 °K at very low stresses (σ=5 10 - 2 g/mm2). Our study reveals a number of anomalies, in particular an effect whereby a sample recovers its dimensions after plastic deformation reaching 7%. The work hardening curves of solid neon are also obtained for comparison. The gravity-induced downward flow of parahydrogen single crystals at helium temperatures mentioned in the literature has not been observed.

  • 8. Aleksandrovskii,, A. N.
    et al.
    Esel'son, V. B.
    Manzhelii, V. G.
    Udovidchenko, B. G.
    Soldatov, Alexander
    Sundqvist, B.
    Negative thermal expansion of fullerite C60 at liquid helium temperatures1997Ingår i: Low temperature physics (Woodbury, N.Y., Print), ISSN 1063-777X, E-ISSN 1090-6517, Vol. 23, nr 11, s. 943-946Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The thermal expansion of fullerite C60 has been measured in the temperature range 2-9 K. A compacted fullerite sample with a diameter of about 6 mm and height of 2.4 mm was used. It was found that at temperatures below ~ 3.4 K the linear thermal expansion coefficient becomes negative. At temperatures above 5 K our results are in good agreement with the available literature data. A qualitative explanation of the results is proposed.

  • 9. Aleksandrovskii, A. N.
    et al.
    Palei, V. V.
    Soldatov, Alexander
    Parbuzin, V. S.
    Thermal expansion of solid deuterohydrogen at helium temperatures1990Ingår i: Soviet Journal of Low Temperature Physics, ISSN 0360-0335, Vol. 16, nr 11, s. 784-785Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For the first time, the thermal expansion of solid deuterohydrogen (HD) is studied in the temperature range 1.2 to 5 K. The isotopic impurity concentrations are 1.5% H2 and 0.4% D2, the other impurities totalling less than 5 · 10 - 4%. It is shown that the thermal expansion coefficient of solid HD can be described by the expression [proportional]HD(K - 1)=1.38 · 10 - 7 T3 in the investigated temperature range. The isothermal compressibility ξT=(34 ± 6) · 10 - 10 Pa - 1 is predicted on the basis of the experimental results and literature data.

  • 10. Aleksandrovskii, A. N.
    et al.
    Soldatov, Alexander
    Manzhelii, V. G.
    Palei, V.V:
    Thermal expansion of solid parahydrogen at helium temperatures1989Ingår i: Soviet Journal of Low Temperature Physics, ISSN 0360-0335, Vol. 15, nr 8, s. 492-493Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal expansion of solid parahydrogen is investigated in the temperature range from 0.9 to 5 K. The content of the orthomodification in parahydrogen is 0.13 at. %, and that of nonhydrogen impurities is less than 2 10 - 3 at. %. No anisotropy in thermal expansion was observed within the experimental error. The temperature dependence of the linear expansion coefficient can be described by the expression α=1.82 10 - 7 T3. The obtained values of α are in good agreement with the available data on compressibility and ([partial derivate]p/[partial derivate]T)V. The Grüneisen coefficient is γ=3αV/CV`T=2.00 ± 0.25.

  • 11.
    Alekseeva, L.A.
    et al.
    B. I. Verkin Institute of Low-temperature Physics and Engineering, National Academy of Sciences of Ukraine.
    Dobryden, Illia
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Unusual changes in the shape of solid parahydrogen with higher than natural isotope content2016Ingår i: Low temperature physics (Woodbury, N.Y., Print), ISSN 1063-777X, E-ISSN 1090-6517, Vol. 42, nr 6, s. 484-490Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The relative elongation epsilon of samples of high purity (99.9999 mol. % with respect to nonhydrogenic impurities) parahydrogen (p-H-2, similar to 0.2% o-H-2) with different amounts of the stable hydrogen isotope deuterium is measured as a function of applied stress sigma at temperatures of 1.8-4.2 K. The samples were subjected to uniaxial tension by stepwise loading. The ratio [D]/[H] of the number [D] of deuterium atoms to the number [H] of p-H-2 hydrogen atoms ranged from 0.0055 +/- 0.0005 at. % up to 0.07 at. %. For deuterium enriched p-H-2, the easy slip dislocation stage vanished from the sigma(epsilon) curves and there was a significant reduction in the total relative elongation of the samples, as well as a substantial increase in the hardening coefficient d sigma/d epsilon. Deformation of samples of p-H-2 with deuterium contents higher than the natural amount produces an unusual change in their shape owing to the appearance of a rotational component of the low-temperature plastic mass transfer

  • 12. Alexandrovskii, A. N.
    et al.
    Esel’son, V. B.
    Manzhelii, V. G.
    Soldatov, Alexander
    Sundqvist, B.
    Udovidchenko, B. G.
    Thermal expansion of single-crystal fullerite C60 at helium temperatures2000Ingår i: Low temperature physics (Woodbury, N.Y., Print), ISSN 1063-777X, E-ISSN 1090-6517, Vol. 26, nr 1, s. 75-80Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The thermal expansion of single-crystal fullerite C60 has been studied in the range of liquid-helium temperatures (2-10 K). At temperatures below ~4.5 K the thermal expansion of fullerite C60 becomes negative, in agreement with the previous results on polycrystalline materials. A qualitative explanation of the results is proposed

  • 13.
    Allali, Naoual
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Covalent functionalization of carbon nanomaterials for bioelectrochemical applications2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Carbon nanotubes (CTNs) are renowned for their exceptional electronic and mechanical properties. Their structure can be considered as rolling up a graphene sheet along a specific crystallographic direction, leading to a 1D confinement of the electronic wavefunction of the delocalized electrons along the perimeter of the cylindrical structure thus obtained. This confinement produces the existence of defined spikes of high intensity in the electronic density of states, called van Hove singularities. These singularities are primordial to understand both the optical and electronic properties of CNTs through electronphonon coupling processes. If the electronic density of states (DoS) is non zero at the Fermi level the nanotube is metallic, otherwise the nanotube is semiconducting. The synthesis of CNTs always produces a mixture of both metallic and semiconducting nanotubes, and this material can be useful to be incorporated at the surface of electrodes for electrochemical devices. The high specific surface area, the high mechanical and thermal stability of CNTs and the low percolation threshold for electron transport in a mat of CNTs render them very attractive for such kind of applications. There is yet a drawback of using raw CNTs: they are not compatible with solvents and modification of their surfaces by chemistry is required to make good suspensions for easy deposition at the electrode surface and to introduce specific functional groups for promoting electron transfer, called electron shuttles.

    The final aim of this thesis is therefore the covalent functionalization of CNTs by electron shuttles and their incorporation at the surface of glassy carbon electrodes for electrochemical devices application. A strategy of chemical grafting in three steps has been chosen: i) a controlled oxidation step in acidic media assisted by microwave irradiation in order to keep the structural integrity of CNTs, so as to save their useful electronic properties; ii) a chloration step to produce acid chloride groups and iii) reaction of these groups with electron shuttles modified by specific linkers. The study was first conducted on very clean HiPCO single-walled CNTs (SWCNTs). This enabled to avoid any disturbing effects of carbonaceous impurities or residual catalytic particles, since their possible effects are extremely controversial in the literature. Once validated, this approach was then conducted with cheaper material including few-walls carbon nanotubes (FWCNTs). The use of FWCNTs compared to SWCNTs was not only beneficial for the production of costeffective electrochemical devices but also for a better durability ofthe final device, the inner nanotubes being not functionalized.

    The challenge was to obtain a functionalization process with enough grafted electron shuttles to obtain a good electrocatalytic activity but maintaining CNTs integrity. The first step is predominant to reach this goal, and requires a very accurate understanding of the nature and the number of defects created in the CNTs structure versus the physico-chemical conditions used. The introduction of defects in the crystallographic structure of CNTs has strong consequences both for the electronic DoS and for the phononic properties of the material. Spectroscopic methods are essential in probing these consequences. UV-visible-near IR absorption spectroscopy is the method of choice to directly probe the existence of van Hove singularities and the oscillator strength associated with the authorized electronic transitions between theses ingularities. Covalent grafting of chemical groups at the surface of CNTs changes both the energy and the intensity of these transitions. However, this spectroscopic method requires solubilizing CNTs in non-absorbing solvents using adequate surfactants. Interactions between surfactant molecules and CNT sidewalls may also alter the position and intensity of electronic transitions between van Hove singularities unrelated to the chemical groups covalently grafted.

    Raman spectroscopy of CNTs involves the electronphonon coupling processes through the resonant electronic enhancement of Raman modes. Double resonance processes are also observed in Raman spectrum of CNTs, for instance with the D-band mode that is actually related to the existence of defects in the graphene structure of CNTs. Therefore, Raman spectroscopy is a widespread analytical method to characterize the structural defects created by covalent functionalization processes. Indeed, the intensity ratio of the D and G bands in the Raman spectrum is correlated to the number of defects. However, CNTs are used as bundles when chemical functionalization is performed, which produces a heterogeneous distribution of chemical species grafted on CNTs. Therefore, we have developed a new protocol to obtain statistically significant data for most of the samples made in this thesis. Nevertheless, this statistical approach is still limited for samples slightly functionalized, whence the idea to use spectroscopic ellipsometry as an alternative method to characterize these samples.

    More specifically, ellipsometric data were collected from UV to the IR part of the electromagnetic spectrum for CNTs functionalized in different conditions. The complex dielectric function was retrieved from the experimental data. A Drude model was used to model the infrared part of the data for raw and acid oxidized CNTs. The optical conductivity of the samples was obtained. These results, combined with other information collected using a set of complementary analytical techniques (Raman scattering, UV-visible-NIR absorption, X-ray photoelectron spectroscopy, thermogravimetric analysis coupled to mass spectrometry, transmission electron microscopy and rare gas volumetric adsorption), show that the microwave-assisted oxidation process actually consists in removing amorphous carbon deposits away from the surface of CNTs and transforming the already existing defects in the CNT structure to oxygen-containing groups such as carboxylic acids.

    Rare gas volumetric adsorption was also used to compare the distribution of chemical groups at the surface of CNT bundles when two different acids are used (HNO3 and H2SO4). The chloration step was also studied by these methods, as well as the final grafting of electron shuttles. Finally, these functionalized CNTs were deposited at the surface of glassy carbon electrodes and used as electron mediators for diaphorase-catalysed oxidation of nicotinamide adenine dinucleotide (NADH). This was a good example of mediated electron transfer for development of electrochemical devices based on NADH recycling and it validated the good electrocatalytic properties of functionalized CNTs for making electrochemical sensors and actuators, opening new perspectives with potential market applications.

  • 14.
    Allali, Naoual
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. LCPME, UMR CNRS-Université de Lorraine, Villers-lès-Nancy, France. SRSMC, UMR CNRS-Université de Lorraine, Faculté des Sciences et Technologies, Vandoeuvre-lès-Nancy, France.
    Urbanova, Veronika
    LCPME, UMR CNRS-Université de Lorraine, Villers-lès-Nancy, France.
    Etienne, Mathieu
    LCPME, UMR CNRS-Université de Lorraine, Villers-lès-Nancy, France.
    Devaux, Xavier
    IJL, UMR CNRS-Université de Lorraine, Nancy Cedex, France.
    Mallet, Martine
    LCPME, UMR CNRS-Université de Lorraine, Villers-lès-Nancy, France.
    Vigolo, Brigitte
    IJL, UMR CNRS-Université de Lorraine, Faculté des Sciences et Technologies, Vandoeuvre-lès-Nancy Cedex, France.
    Adjizian, Jean-Joseph
    IMN, UMR CNRS-Université de Nantes, Nantes, France.
    Ewels, Chris
    IMN, UMR CNRS-Université de Nantes, Nantes, France.
    Öberg, Sven
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Soldatov, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    McRae, Edward
    IJL, UMR CNRS-Université de Lorraine, Faculté des Sciences et Technologies,Vandoeuvre-lès-Nancy Cedex, France.
    Fort, Yves
    SRSMC, UMR CNRS-Université de Lorraine, Faculté des Sciences et Technologies, Vandoeuvre-lès-Nancy, France.
    Dossot, Manuel
    LCPME, UMR CNRS-Université de Lorraine, Villers-lès-Nancy, France.
    Mamane, Victor
    Institut de Chimie de Strasbourg, UMR CNRS-Université de Strasbourg, Strasbourg, France.
    Accurate control of the covalent functionalization of single-walled carbon nanotubes for the electro-enzymatically controlled oxidation of biomolecules2018Ingår i: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 9, s. 2750-2762Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Single-walled carbon nanotubes (SWCNTs) were functionalized by ferrocene through ethyleneglycol chains of different lengths (FcETGn) and the functionalized SWCNTs (f-SWCNTs) were characterized by different complementary analytical techniques. In particular, high-resolution scanning electron transmission microscopy (HRSTEM) and electron energy loss spectroscopy (EELS) analyses support that the outer tubes of the carbon-nanotube bundles were covalently grafted with FcETGn groups. This result confirms that the electrocatalytic effect observed during the oxidation of the reduced form of nicotinamide adenine dinucleotide (NADH) co-factor by the f-SWCNTs is due to the presence of grafted ferrocene derivatives playing the role of a mediator. This work clearly proves that residual impurities present in our SWCNT sample (below 5 wt. %) play no role in the electrocatalytic oxidation of NADH. Moreover, molecular dynamic simulations confirm the essential role of the PEG linker in the efficiency of the bioelectrochemical device in water, due to the favorable interaction between the ETG units and water molecules that prevents π-stacking of the ferrocene unit on the surface of the CNTs. This system can be applied to biosensing, as exemplified for glucose detection. The well-controlled and well-characterized functionalization of essentially clean SWCNTs enabled us to establish the maximum level of impurity content, below which the f-SWCNT intrinsic electrochemical activity is not jeopardized.

  • 15.
    Allali, Naoual
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Urbanova, Veronika
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Etienne, Mathieu
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Mallet, Martine
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Devaux, Xavier
    Département P2M, Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine.
    Vigolo, Brigitte
    Département CP2S, Institut Jean Lamour UMR 7198 CNRS-Université de Lorraine.
    Fort, Yves
    Laboratoire de Structure et Réactivité des Systèmes Moléculaires Complexes, UMR 7565 CNRS–Université de Lorraine, 54506 Vandoeuvre-les-Nancy.
    Walcarius, Alain
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Noël, Maxime
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    McRae, Edward
    Département CP2S, Institut Jean Lamour UMR 7198 CNRS-Université de Lorraine.
    Soldatov, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Dossot, Manuel
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Mamane, Victor
    Laboratoire de Structure et Réactivité des Systèmes Moléculaires Complexes, UMR 7565 CNRS–Université de Lorraine, 54506 Vandoeuvre-les-Nancy.
    Electrocatalytic effect towards NADH induced by HiPco single-walled carbon nanotubes covalently functionalized by ferrocene derivatives2013Ingår i: 2012 MRS Fall Meeting: Symposium YY – Low-Voltage Electron Microscopy and Spectroscopy for Materials Characterization, Cambridge University Press, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    The present work reports the covalent functionalization of single-walled carbon nanotubes (SWCNTs) by ferrocene derivatives with polyethyleneglycol linkers. A very clean initial sample was chosen to avoid any residual catalyst and carbon impurities. Functionalized SWCNTs (f-CNTs) are deposited on the surface of a glassy carbon electrode (GCE) and this modified electrode is used for oxidizing the cofactor NADH (dihydronicotinamide adenine dinucleotide) in the presence of diaphorase. A clear electrocatalytic effect is evidenced, which can only be attributed to the f-CNTs.

  • 16.
    Allali, Naoual
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Urbanova, Veronika
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Mamane, Victor
    Laboratoire de Structure et Réactivité des Systèmes Moléculaires Complexes, UMR 7565 CNRS–Université de Lorraine, 54506 Vandoeuvre-les-Nancy.
    Etienne, Mathieu
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Mallet, Martine
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Devaux, Xavier
    Institut Jean Lamour, Department P2M, UMR 7198 CNRS–Université de Lorraine, Ecole des Mines, 54042 Nancy.
    Vigolo, Brigitte
    Institut Jean Lamour, Department CP2S, UMR 7198 CNRS–Université de Lorraine, 54506 Vandoeuvre-les-Nancy.
    Fort, Yves
    Laboratoire de Structure et Réactivité des Systèmes Moléculaires Complexes, UMR 7565 CNRS–Université de Lorraine, 54506 Vandoeuvre-les-Nancy.
    Walcarius, Alain
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Noël, Maxime
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Soldatov, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    McRae, Edward
    Institut Jean Lamour, Department CP2S, UMR 7198 CNRS–Université de Lorraine, 54506 Vandoeuvre-les-Nancy.
    Dossot, Manuel
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Covalent functionalization of few-wall carbon nanotubes by ferrocene derivatives for bioelectrochemical devices2012Ingår i: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 249, nr 12, s. 2349-2352Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present work reports the covalent functionalization of few-wall CNTs (FWCNTs) by ferrocene derivatives to (i) improve their dispersion efficiency in water and (ii) graft electroactive chemical groups on their side-walls in order to promote electron transfer to biomolecules. The functionalized CNTs (f-CNTs) are used to modify a glassy carbon electrode and this modified electrode is used for oxidizing the cofactor NADH (dihydronicotinamide adenine dinucleotide).

  • 17.
    Allali, Naoual
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Urbanova, Veronika
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Mamane, Victor
    Laboratoire de Structure et Réactivité des Systèmes Moléculaires Complexes, UMR 7565 CNRS–Université de Lorraine, 54506 Vandoeuvre-les-Nancy.
    Waldbock, Jeremy
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Etienne, Mathieu
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Mallet, Martine
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Devaux, Xavier
    Département P2M, Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine.
    Vigolo, Brigitte
    Département CP2S, Institut Jean Lamour UMR 7198 CNRS-Université de Lorraine.
    Fort, Yves
    Laboratoire de Structure et Réactivité des Systèmes Moléculaires Complexes, UMR 7565 CNRS–Université de Lorraine, 54506 Vandoeuvre-les-Nancy.
    Walcarius, Alain
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564, CNRS–University of Lorraine.
    Noël, Maxime
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Soldatov, Alexander
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    McRae, Edward
    Département CP2S, Institut Jean Lamour UMR 7198 CNRS-Université de Lorraine.
    Dossot, Manuel
    Département CP2S, Institut Jean Lamour UMR 7198 CNRS-Université de Lorraine.
    Few-wall carbon nanotubes covalently functionalized by ferrocene groups for bioelectrochemical devices2012Ingår i: MRS Online Proceedings Library, Cambridge University Press, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    The present work reports the covalent functionalization of few-wall CNTs (FWCNTs) by ferrocene derivatives to i) improve their dispersion efficiency in water and ii) to graft electroactive chemical groups on their side-walls in order to promote electron transfer to biomolecules. The functionalized CNTs (f-CNTs) are used to modify a glassy carbon electrode and this modified electrode is used for oxidizing the cofactor NADH (dihydronicotinamide adenine dinucleotide).

  • 18.
    Almqvist, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Fractal analysis of scanning probe microscopy images1996Ingår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 355, nr 1-3, s. 221-228Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The accuracy and precision of several algorithms, including newly developed, for calculating the fractal dimension from scanning probe microscopy images of material surfaces are investigated. The algorithms are based on the area-perimeter method, a variance method or versions of the structure function method. The latter two methods show good correspondence to computer simulated images, with known fractal dimensions, and have successfully been applied also on real images. The results show that these two methods give reliable fractal dimensions and are well suited to describe surface roughness quantitatively.

  • 19.
    Almqvist, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Scanning probe microscopy: Applications1994Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 20.
    Almqvist, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Studies of plasma-facing materials and macromolecules using scanning probe microscopy1995Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The main topic of this thesis is experimental analysis of material surfaces using scanning probe microscopies. These microscopes are used for characterization through high-resolution topographical imaging, but also for controlled modification of surfaces and molecules. The surface characterization includes evaluation and development of fractal methods for surface roughness determination. The term modification is used for manipulating the structures on a microscale by scraping them with a tiny tip. The major application of this technique in the present work is the analysis of effects induced by plasma-surface interactions. Such studies are fundamental in the understanding of erosion and deposition processes on the first wall in controlled fusion devices. In this work, scanning probe microscopes were for the first time used for studying such plasma-facing materials. Both the surface structure and composition have to be known in order to evaluate new wall-materials for fusion reactors. The materials studied here are graphites, SiC/Al coatings, graphite-silicon mixtures and various silicon carbide based composites. They were all exposed to plasmas, either to lowenergy deuterium plasmas and ions in laboratory experiments, or to the plasma in a socalled tokamak. The results show the usefulness of these high-resolution microscopes in the study of plasma-surface interaction. Several other surface sensitive techniques were also applied, at the home laboratories of our collaborators, the most important ones being Rutherford backscattering spectroscopy and nuclear reaction analysis. The scanning probe microscopy in combination with the ion-beam analysis made it possible to trace fine structural features on the surfaces and to measure the surface roughness. The main results are: (i) the detection of the initial stages of bubble/blister formation on CSi mixtures, SiC/AI coatings and graphites; (ii) the morphological changes and the physical properties of the silicon carbide composites; (iii) the distinction of radiation damages on different phases of multicomponent composites; (iv) the estimation of layer thickness with scanning probe microscopy; (v) the determination of the structure of codeposited layers formed during exposure in a tokamak; (vi) the uptake of deuterium by the materials. The atomic force microscope has also been used to study the human protein spectrin, and we managed to image free spectrins with molecular resolution in an almost natural environment. The elongated spectrin macromolecule was found to be 100 rim long and 5 nm broad. Indications of a substructure were observed. The force between the sensor tip and the molecules was crucial, both for sample movement, manipulation and image resolution. Therefore, the instrument was rebuilt to operate with so called tapping-mode in liquid. Preliminary results with this method on spectrin are presented.

  • 21.
    Almqvist, Nils
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Bhatia, R
    Neuroscience Research Institute, University of California, Santa Barbara.
    Primbs, G
    Neuroscience Research Institute, University of California, Santa Barbara.
    Desai, N
    NutraSweet Company, Chicago.
    Banerjee, S
    Department of Chemical Engineering, University of California, Santa Barbara.
    Lal, R
    Neuroscience Research Institute, University of California, Santa Barbara.
    Elasticity and adhesion force mapping reveals real-time clustering of growth factor receptors and associated changes in local cellular rheological properties2004Ingår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 86, nr 3, s. 1753-1762Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cell surface macromolecules such as receptors and ion channels serve as the interface link between the cytoplasm and the extracellular region. Their density, distribution, and clustering are key spatial features influencing effective and proper physical and biochemical cellular responses to many regulatory signals. In this study, the effect of plasma-membrane receptor clustering on local cell mechanics was obtained from maps of interaction forces between antibody-conjugated atomic force microscope tips and a specific receptor, a vascular endothelial growth factor (VEGF) receptor. The technique allows simultaneous measurement of the real-time motion of specific macromolecules and their effect on local rheological properties like elasticity. The clustering was stimulated by online additions of VEGF, or antibody against VEGF receptors. VEGF receptors are found to concentrate toward the cell boundaries and cluster rapidly after the online additions commence. Elasticity of regions under the clusters is found to change remarkably, with order-of-magnitude stiffness reductions and fluidity increases. The local stiffness reductions are nearly proportional to. receptor density and, being concentrated near the cell edges, provide a mechanism for cell growth and angiogenesis.

  • 22.
    Almqvist, Nils
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Delamo, Y
    Neuroscience Research Institute, University of California.
    Smith, BL
    Thomson, NH
    Laboratoire d'Océanographie Biologique (LOB).
    Bartholdson, A
    Department of Physics and Astronomy, University of Leeds.
    Lal, R
    Marine Science Institute, University of California.
    Brzezinski, M
    Neuroscience Research Institute, University of California.
    Hansma, PK
    Luleå tekniska universitet.
    Micromechanical and structural properties of a pennate diatom investigated by atomic force microscopy2001Ingår i: Journal of Microscopy, ISSN 0022-2720, E-ISSN 1365-2818, Vol. 202, nr 3, s. 518-532Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanisms behind natural nanofabrication of highly structured silicas are increasingly being investigated. We have explored the use of a standard Nanoscope III Multimode atomic force microscope (AFM) to study the silica shell of diatoms. The delicate structures of the shell surface of the diatom Navicula pelliculosa (Breb.) Hilse were imaged and the shell's micromechanical properties were measured semi-quantitatively with a resolution down to approximately 10 nm. The technique to measure elasticity and hardness with the AFM was demonstrated to be useable even on these hard glass-like surfaces, Different experimental configurations and evaluation methods were tested, They gave a consistent result of the shell micromechanical properties, The first results showed that the diatom shell's overall hardness and elasticity was similar to that of known silicas. However, regions with different mechanical proper ties were distinguished. The elastic modulus varied from 7 to 20 GPa, from 20 to 100 GPa and from 30 to hundreds of GPa depending on the location. In general, the hardness measurements showed similar spatial differences, The hardness values ranged from 1 to 12 GPa but one specific part of the shell was even harder. Hence, certain localized regions of the shell were significantly harder or more elastic. These regions coincide with known characteristic features and mechanisms appearing at the different stages of the shell's growth. These results show that this method serves as a complementary tool in the study of silica biomineralization, and can detect eventual crystalline phases.

  • 23.
    Almqvist, Nils
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Fredriksson, Sverker
    Backman, Lars
    Imaging human erythrocyte spectrin with atomic force microscopy1994Ingår i: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 25, nr 3, s. 227-232Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Isolated spectrin covalently attached to a surface in a liquid environment as well as dried on mica has been studied with a contact-mode atomic force microscope. Both pyramidal and conical-type cantilever tip facets were used in the AFM. Our images show structures and give dimensions that correlate well with previous structural studies using transmission electron microscopy.

  • 24.
    Almqvist, Nils
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Fredriksson, Sverker
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Rubel, Marek
    Royal Institute of Technology, Physics Department, S-10405 Stockholm, Sweden.
    Emmoth, Birger
    Royal Institute of Technology, Physics Department, S-10405 Stockholm, Sweden.
    SFM and STM topographic studies of carbon-based surfaces exposed to deuterium plasma1994Ingår i: Book of abstracts: Microprobe Symposium, Vadstena, April 25-26, 1994, 1994Konferensbidrag (Refereegranskat)
  • 25.
    Almqvist, Nils
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Quist, Arjan P
    Mälardalen University, Department of Chemical Engineering, Box 325 SE-63105 Eskilstuna, Sweden.
    Lal, Ratnesh
    University of California, Neuroscience Research Institute, Santa Barbara, CA 93106, USA.
    Elastic properties of living cells studied by multimodal atomic force microscopy2000Ingår i: Abstract book Nordic-Baltic SPM Workshop, 2000: abstract #1, 2000Konferensbidrag (Refereegranskat)
  • 26.
    Almqvist, Nils
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Rubel, M.
    Franconi, E.
    Surface characterization of SiC composites exposed to deuterium ions, using atomic force microscopy1995Ingår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 201, nr 1-2, s. 277-285Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the influence of deuterium plasma on the surface structure of SiC based composites. The substrates are silicon carbides doped with titanium diboride, aluminium nitride or graphite. A number of surface sensitive techniques are used to characterize the substrates, before and after exposure to low-energy deuterium ions, the main method being atomic force microscopy. The microscope reveals distinct morphological changes on the irradiated samples. The density and surface area of the samples probably influence the content of deuterium in the surfaces. However, this study shows that the amount of graphite aggregated on the surfaces is of crucial importance for the uptake of deuterium.

  • 27.
    Almqvist, Nils
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Rubel, M.
    Physics Department - Frescati, Royal Institute of Technology, Association EURATOM-NFR.
    Fredriksson, Sverker
    Emmoth, B.
    Physics Department - Frescati, Royal Institute of Technology, Association EURATOM-NFR.
    Wienhold, P.
    Institute of Plasma Physics, Forschungszentrum Jülich, Association EURATOM-KFA.
    Ilyinsky, L.
    Institute of Electrical Engineering, St. Petersburg.
    AFM and STM characterization of surfaces exposed to high flux deuterium plasma1995Ingår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 220-222, nr 1-3, s. 917-921Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports the results of scanning tunneling (STM) and atomic force microscopy (AFM) studies of D+ irradiated graphite and graphite-silicon mixtures. The microscopes were used for studying surface topography and for measuring the surface roughness. The substrates were exposed at various temperatures (60 and 700°C) to different doses of deuterium ions in simulators of plasma - surface interactions and in the TEXTOR tokamak. Also nuclear reaction analysis (NRA) and Rutherford backscattering spectroscopy were applied for the qualitative and quantitative determination of surface composition. The initial stages of radiation damage, nanometer-sized bubbles/blisters, were found in plasma-eroded surfaces. These structures only appeared in the graphite phase on the multicomponent material. The microroughness of the surfaces was measured. We also used the AFM for probing the thickness of the plasma-modified layers. The results correlate with the presence of deuterium measured by NRA depth-profiling. Moreover, the AFM reveals the co-deposited layers formed on surfaces facing the tokamak plasma. The appearance of these layers is clearly correlated to the amount of co-deposited atoms.

  • 28.
    Almqvist, Nils
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Rubel, M.
    Nannetti, C.A.
    Franconi, E.
    Fredriksson, Sverker
    Emmoth, B.
    Scanning probe microscopy and thermo-mechanical characterization of silicon carbide composites1995Ingår i: Fourth Euro-Ceramics: the proceedings of the Fourth European Ceramic Society Conference / [ed] S. Meriani; V. Sergo, Gruppo Ed. Faenza Ed. , 1995, Vol. 3, s. 361-368Konferensbidrag (Refereegranskat)
    Abstract [en]

    series of SiC-based composites was obtained by sintering. Since such materials are considered for fusion applications, their thermal shock resistance and behaviour under deuterium irradiation are of primary interest. Extensive bulk and surface characterisation of pure and doped (AlN, TiB2, graphite) silicon carbides treated by a deuterium plasma was carried out. The change in surface structure following irradiation is addressed, and major factors influencing deuterium retention are discussed.

  • 29.
    Almqvist, Nils
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Rubel, M.
    Royal Institute of Technology, Physics Department-Frescati, Association EURATOM-NFR.
    Wienhold, P.
    Institute of Plasma Physics, Forschungszentrum Jülich, Association EURATOM-KFA.
    Fredriksson, Sverker
    Roughness determination of plasma-modified surface layers with atomic force microscopy1995Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 270, nr 1-2, s. 426-430Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Graphite surfaces exposed to the deuterium plasma in the TEXTOR tokamak were characterized in detail by means of scanning probe microscopy, ion beam analysis and colorimetry methods. The aim is to study the composition and structure of thin layer deposits formed on surfaces subjected to the tokamak plasma. The surface roughness was measured and parametrized in terms of fractal dimension and scaling constant. Several different methods for the fractal analysis of plasma-exposed surfaces have been critically evaluated. The main emphasis of this paper is on the correlation between surface roughness (fractal parameters), the amount of deposited atoms and the layer thickness.

  • 30.
    Almqvist, Nils
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Thomson, Neil H.
    Smith, Bettye L.
    Stucky, Galen D.
    Morse, Daniel E.
    Hansma, Paul K.
    Methods for fabricating and characterizing a new generation of biomimetic materials1999Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 7, nr 1, s. 37-43Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bringing together current ideas in the fields of biomineralization and composite laminate materials, we have attempted to fabricate model materials that mimic abalone nacre through the rapid assembly of inorganic tablets, such as talc. Several physical methods were tested to aid the orientation of the talc tablets in fluid suspensions with a low percentage, 10% by dry weight, of organic binding material. The orientation of talc tablets in the synthesized composites was characterized by X-ray diffraction and scanning electron microscopy. The modulus of rupture of the materials was measured in a three-point bending test. We demonstrate that the alignment of tablets increases by the use of physical methods and from chemical surface treatment. Important factors to consider in making materials that mimic abalone nacre are discussed. Important factors to consider in making materials that mimic abalone nacre are discussed.

  • 31.
    Alvi, Sajid Ali
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Ghamgosar, Pedram
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Rigoni, Federica
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Vomiero, Alberto
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Akhtar, Farid
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Adaptive nanolaminate coating by atomic layer deposition2019Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Atomic layer deposition (ALD) was used to deposit ZnO/Al2O3/V2O5 nanolaminate coatings to demonstrate a coating system with temperature adaptive frictional behaviour. The nanolaminate coating exhibited excellent conformity and crack-free coating of thickness 110 nm over Inconel 718 substrate. The ALD trilayer coating showed a hardness and elastic modulus of 12 GPa and 193 GPa, respectively. High-temperature tribology of the nanolaminate trilayer was tested against steel ball in dry sliding condition at 25 °C (room temperature, RT), 200 °C, 300 °C, and 400 °C. It was found that the nanolaminate coating showed a low coefficient of friction (COF) and wear rate at RT and 300 °C. The trilayer coating was found intact and stable at all temperatures during the friction tests. The adaptability of nanolaminate coating with the temperature was verified by performing the cyclic friction test at 300 °C and RT. The low COF and wear rate had been attributed to the (100) and (002) basal plane sliding of ZnO top layer, and the interlayer sliding of weakly bonded planes parallel to (001) plane in V2O5 bottom layer. Furthermore, even after the removal of ZnO coating during the tribotest, the bottom V2O5 layer coating stabilized the COF and wear rate at RT and 300 °C.

  • 32.
    Amin, Sidra
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro, Pakistan.Department of Chemistry, Shaheed Benazir Bhutto University, Shaheed Benazirabad, Pakistan.
    Tahira, Aneela
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Solangi, Amber
    National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro, Pakistan.
    Beni, Valerio
    RISE Acreo, Research Institute of Sweden, Norrköping, Sweden.
    Morante, J.R
    Catalonia Institute for Energy Research (IREC), Barcelona, Spain.
    Liu, Xianjie
    Department of Physics, Chemistry and Biology, Surface Physics and Chemistry, Linköping University, Faculty of Science & Engineering, Sweden.
    Falhman, Mats
    Department of Physics, Chemistry and Biology, Surface Physics and Chemistry, Linköping University, Faculty of Science & Engineering, Sweden.
    Mazzaro, Raffaello
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Ibupoto, Zafar
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Institute of Chemistry, University of Sindh, Jamshoro, Pakistan.
    Vomiero, Alberto
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    A practical non-enzymatic urea sensor based on NiCo2O4 nanoneedles2019Ingår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, nr 25, s. 14443-14451Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose a new facile electrochemical sensing platform for determination of urea, based on a glassy carbon electrode (GCE) modified with nickel cobalt oxide (NiCo2O4) nanoneedles. These nanoneedles are used for the first time for highly sensitive determination of urea with the lowest detection limit (1 μM) ever reported for the non-enzymatic approach. The nanoneedles were grown through a simple and low-temperature aqueous chemical method. We characterized the structural and morphological properties of the NiCo2O4 nanoneedles by TEM, SEM, XPS and XRD. The bimetallic nickel cobalt oxide exhibits nanoneedle morphology, which results from the self-assembly of nanoparticles. The NiCo2O4 nanoneedles are exclusively composed of Ni, Co, and O and exhibit a cubic crystalline phase. Cyclic voltammetry was used to study the enhanced electrochemical properties of a NiCo2O4 nanoneedle-modified GCE by overcoming the typical poor conductivity of bare NiO and Co3O4. The GCE-modified electrode is highly sensitive towards urea, with a linear response (R2 = 0.99) over the concentration range 0.01–5 mM and with a detection limit of 1.0 μM. The proposed non-enzymatic urea sensor is highly selective even in the presence of common interferents such as glucose, uric acid, and ascorbic acid. This new urea sensor has good viability for urea analysis in urine samples and can represent a significant advancement in the field, owing to the simple and cost-effective fabrication of electrodes, which can be used as a promising analytical tool for urea estimation.

  • 33.
    Amin, Sidra
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro, Pakistan. Department of Chemistry, Shaheed Benazir Bhutto University, Shaheed Benazirabad, Pakistan.
    Tahira, Aneela
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Solangi, Amber
    National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro, Pakistan.
    Mazzaro, Raffaello
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Ibupoto, Zafar
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Department of Chemistry, Shaheed Benazir Bhutto University, Shaheed Benazirabad, Pakistan.
    Vomiero, Alberto
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    A sensitive enzyme-free lactic acid sensor based on NiO nanoparticles for practical applications2019Ingår i: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 11, s. 3578-3583Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A facile and efficient electrochemical sensing platform has been successfully exploited for the first time for the determination of lactic acid using a nickel oxide (NiO) nanoparticle-modified glassy carbon electrode (GCE). Nickel oxide nanoparticles were prepared by a chemical growth method using different quantities of arginine as a soft template. The structural and morphological properties of NiO nanoparticles were characterized by Raman spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Cyclic voltammetry (CV) was used to study the electrochemical properties of various samples. The modified electrode is highly sensitive and presents a linear response over a wide range (0.005–5 mM) of lactic acid concentrations in 0.1 M NaOH. The detection limit for the sensor was found to be 5.7 μM, and it exhibits good stability. Furthermore, the sensor shows excellent selectivity in the presence of common interfering species. The lactic acid sensor showed good viability for lactic acid analysis in real samples (milk, yogurt and red wine) and demonstrated significant advancement in sensor technology for practical applications.

  • 34.
    Andersson, L.C.
    et al.
    Luleå tekniska universitet.
    Hauska, Hans
    Luleå tekniska universitet.
    Lineament mapping in Northern Sweden from Landsat images using orthogonal image transforms1980Ingår i: Sixth Annual Symposium Machine Processing of Remotely Sensed Data and Soil Information Systems and Remote Sensing and Soil Survey, June 3 - 6, 1980, Purdue Univ., Laboratory for Applications of Remote Sensing, West Lafayette, Ind / [ed] P.G. Burroff, New York: IEEE Communications Society, 1980, s. 147-157Konferensbidrag (Refereegranskat)
    Abstract [en]

    The emphasis of this paper is put on mapping of geological linear structures, and in particular the correlation between these structures orientation and geological or geophysical data. It is also the intention of the authors to present a method to map these structures more objectively than up to now

  • 35.
    Andersson, L.C.
    et al.
    Luleå tekniska universitet.
    Hauska, Hans
    Luleå tekniska universitet.
    Lineaments analysis using global and local Fourier transforms1983Ingår i: Proceedings of the fourth international conference on basement tectonics, Oslo, Norway, August 10-14, 1981 / [ed] Roy H. Gabrielsen, Salt Lake City: International Basement Tectonics Association , 1983, s. 63-69Konferensbidrag (Refereegranskat)
  • 36. Andersson, O.
    et al.
    Soldatov, Alexander
    Sundqvist, B.
    Thermal conductivity of C60 at pressures up to 1 GPa and temperatures in the 50-300 K range1996Ingår i: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 54, nr 5, s. 3093-3100Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The thermal conductivity λ of C60 shows anomalies near 260 K and 90 K which are associated with the well-established phase transition and glass transition, respectively. Both transition temperatures increase with pressure, at the rates 120 K GPa-1 and 62 K GPa-1, respectively. With increasing temperature, λ of the simple cubic (sc) phase increased below 170 K (glasslike behavior) but decreased above. The glasslike behavior of λ is probably due to a substantial amount of lattice defects. Possible reasons for the change of sign of dλ/dT near 170 K are discussed. In the face centered cubic (fcc) phase (T≳260 K at atmospheric pressure) λ was almost independent of temperature, a behavior which is far from that of an ordered crystal (λ∝T-1 for T≳Debye temperature). This result can be attributed to the molecular orientational disorder of the fcc phase. The relaxation behavior associated with the glassy state and its unusually strong dependence on thermal history are discussed briefly, and data which support a previously reported relaxation model are presented. At room temperature, the density dependencies of λ, (∂ lnλ/∂ lnρ)T, were 5.5 and 9.5 for the fcc and sc phases, which are values typical for an orientationally disordered phase and a normal crystal phase, respectively.

  • 37. Andersson, O.
    et al.
    Soldatov, Alexander
    Sundqvist, B.
    Thermal conductivity of C60 under high pressure1995Ingår i: Science and technology of fullerene materials: symposium held November 28 - December 2, 1994, Boston, Massachusetts, U.S.A / [ed] Patrick Bernier, Pittsburgh, Pa: Materials Research Society, 1995, s. 549-554Konferensbidrag (Refereegranskat)
  • 38. Andersson, O.
    et al.
    Soldatov, Alexander
    Sundqvist, Bertil
    Reorientational relaxation in C60 following a pressure induced change in the pentagon/hexagon equilibrium ratio1995Ingår i: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 206, nr 3-4, s. 260-264Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The orientational structure of C60 depends on pressure and temperature. Pressurization below the glass transition temperature Tg can freeze in non-equilibrium orientational structures. The relaxation of such structures on heating through Tg has been studied through thermal conductivity measurements and the effects observed are explained in a simple model.

  • 39. Anoushirvani, B.
    et al.
    Enström, Daniel
    Fredriksson, Sverker
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Hansson, Johan
    Ökvist, P.
    Nicolaidis, A.
    Ekelin, Svante
    Kungliga tekniska högskolan, KTH.
    Gamma-ray bursts from primordial quark objects in space1997Ingår i: Proceedings of the Joint Meeting of the Networks 'The Fundamental Structure of Matter' and 'Tests of the Electroweak Symmetry Breaking', Ouranoupolis, Greece, May 1997, 1997Konferensbidrag (Refereegranskat)
    Abstract [en]

    We investigate the possibility that gamma-ray bursts originate in a concentric spherical shell with a given average redshift and find that this is indeed compatible with the data from the third BATSE (3B) catalog. It is also shown that there is enough freedom in the choice of unknown burst properties to allow even for extremely large distances to the majority of bursts. Therefore, we speculate about an early, and very energetic, origin of bursts, and suggest that they come from phase transitions in massive objects of pure quark matter, left over from the Big Bang.

  • 40.
    Anselmino, M.
    et al.
    Dipertemento di Fisica Teoria, Universita di Torino and INFS.
    Boglione, M.
    Department of Physics and Astronomy, Vrije Universitet Amsterdam.
    Hansson, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Murgia, F.
    Institute Nazionale Fisica Nucleare, Seizone di Cagliari.
    Predictions for single spin asymmetries in ℓ parrow -> π X and γ * parrow -> π X2000Ingår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 13, nr 3, s. 519-526Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Predictions for the single transverse spin asymmetry AN in semi-inclusive DIS processes are given; non-negligible values of AN may arise from spin effects in the fragmentation of a polarized quark into a final hadron with a transverse momentum ěc k⊥ with respect to the jet axis, the so-called Collins effect. The elementary single spin asymmetry of the fragmenting quark has been fixed in a previous paper, by fitting data on parrow p -> π X, and by assuming that the QCD factorization theorem holds also when transverse momenta are taken into account. The predictions given here are based on the assumption that the Collins effect is the only cause of the observed single spin asymmetries in parrow p -> π X. Eventual spin and ěc k⊥ dependences in the quark distribution functions, the so-called Sivers effect, are also discussed.

  • 41. Anselmino, M.
    et al.
    Boglione, Mariaelena
    Hansson, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Burgia, F.
    Inclusive production of hadrons in lepton (polarized) p (polarized) ---> h (polarized) X and spin measurements1996Ingår i: Proceedings of International Workshop on Deep Inelastic Scattering and Related Phenomena, DIS 96, 1996, s. 583-589Konferensbidrag (Refereegranskat)
    Abstract [en]

    We discuss the production of polarized hadrons in polarized lepton nucleon interactions and show that the helicity density matrix of the hadron, when measurable, can give information on the spin structure of the nucleon and the spin dependence of the quark fragmentation process. Single spin asymmetries in the $\ell N^\uparrow \to hX$ process are also briefly discussed.

  • 42. Anselmino, M.
    et al.
    Boglione, Mariaelena
    Hansson, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Murgia, F.
    Spin measurements in l p ---> h X deep inelastic scattering1997Ingår i: SPIN 96: proceedings; September 10-14, 1996, Amsterdam, the Netherlands, Singapore: World Scientific Publishing Co Pte Ltd , 1997, s. 346-348Konferensbidrag (Refereegranskat)
    Abstract [en]

    The production of hadrons in polarized lepton-nucleon deep inelastic scattering is discussed. The helicity density matrix of the hadron is computed within the QCD hard scattering formalism and its elements are shown to yield information on the spin structure of the nucleon and the spin dependence of the quark fragmentation process. The case of $\rho$ vector mesons is considered in more detail and estimates are given.

  • 43.
    Anselmino, Mauro
    Luleå tekniska universitet.
    Diquarks1992Rapport (Övrigt vetenskapligt)
  • 44.
    Anselmino, Mauro
    et al.
    Dipartimento di Fisica Teorica, Università di Torino and Istituto Nazionale di Fisica Nucleare, Sezione di Torino.
    Boglione, Maria
    Dipartimento di Fisica Teorica, Università di Torino and Istituto Nazionale di Fisica Nucleare, Sezione di Torino.
    Hansson, Johan
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Murgia, Francesco
    Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari.
    Polarized inclusive leptoproduction, lN→hX, and the hadron helicity density matrix ρ(h): Possible measurements and predictions1996Ingår i: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 54, nr 1, s. 828-837Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We discuss the production of hadrons in polarized lepton-nucleon interactions and in the current jet fragmentation region; using the QCD hard scattering formalism we compute the helicity density matrix of the hadron and show how its elements, when measurable, can give information on the spin structure of the nucleon and the spin dependence of the quark fragmentation process. The cases of ρ vector mesons and Λ baryons are considered in more detail and, within simplifying assumptions, some estimates are given

  • 45.
    Anselmino, Mauro
    et al.
    Dipartimento di Fisica Teorica, Università di Torino and Istituto Nazionale di Fisica Nucleare, Sezione di Torino.
    Predazzi, Enrico
    Dipartimento di Fisica Teorica, Università di Torino and Istituto Nazionale di Fisica Nucleare, Sezione di Torino.
    Ekelin, Svante
    Kungliga tekniska högskolan, KTH.
    Fredriksson, Sverker
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Lichtenberg, D.B.
    Department of Physics, Indiana University.
    Diquarks1993Ingår i: Reviews of Modern Physics, ISSN 0034-6861, E-ISSN 1539-0756, Vol. 65, nr 4, s. 1199-1233Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is becoming increasingly clear that the concept of a diquark (a two-quark system) is important for understanding hadron structure and high-energy particle reactions. According to our present knowledge of quantum chromodynamics (QCD), diquark correlations arise in part from spin-dependent interactions between two quarks, from quark radial or orbital excitations, and from quark mass differences. Diquark substructures affect the static properties of baryons and the mechanisms of baryon decay. Diquarks also play a role in hadron production in hadron-initiated reactions, deep-inelastic lepton scattering by hadrons, and in e+e- reactions. Diquarks are important in the formation and properties of baryonium and mesonlike semistable states. Many spin effects observed in high-energy exclusive reactions pose severe problems for the pure quark picture of baryons and might be explained by the introduction of diquarks as hadronic constituents. There is considerable controversy, not about the existence of diquarks in hadrons, but about their properties and their effects. In this work a broad selection of the main ideas about diquarks is reviewed.

  • 46.
    Antipov, Sergey V.
    et al.
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Gustafsson, Magnus
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Nyman, Gunnar
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Isotope effect in the formation of carbon monoxide by radiative association2013Ingår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 430, nr 2, s. 946-950Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Rate coefficients for the formation of 12CO and 13CO isotopologues of carbon monoxide by radiative association for T = 10–20 000 K are calculated using a quantum mechanical approach. It is shown that the presence of the potential barrier on the A1Π electronic state of CO leads to different formation channels for the isotopologues at low temperatures. The corresponding rate coefficients are fitted to an analytic formula.

  • 47.
    Antipov, Sergey V.
    et al.
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Gustafsson, Magnus
    Department of Chemistry, University of Gothenburg.
    Nyman, Gunnar
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Spin-orbit and rotational couplings in radiative association of C(3P) and N(4S) atoms2011Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 135, nr 18, artikel-id 184302Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The role of spin-orbit and rotational couplings in radiative association of C(3 P) and N(4 S) atoms is investigated. Couplings among doublet electronic states of the CN radical are considered, giving rise to a 6-state model of the process. The solution of the dynamical problem is based on the L2 method, where a complex absorbing potential is added to the Hamiltonian operator in order to treat continuum and bound levels in the same manner. Comparison of the energy-dependent rate coefficients calculated with and without spin-orbit and rotational couplings shows that the couplings have a strong effect on the resonance structure and low-energy baseline of the rate coefficient.

  • 48.
    Antipov, Sergey V.
    et al.
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Sjölander, Tobias
    Department of Chemistry, University of Gothenburg.
    Nyman, Gunnar
    Department of Chemistry and Molecular Biology, University of Gothenburg.
    Gustafsson, Magnus
    Department of Chemistry, University of Gothenburg.
    Rate coefficient of CN formation through radiative association: A theoretical study of quantum effects2009Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 131, nr 7, artikel-id 74302Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Radiative association of CN is simulated using a quantum dynamical as well as a semiclassical approach. A comparison of the resulting energy-resolved cross sections reveals striking quantum effects that are due to shape resonances. These, in turn, arise because of states that are quasibound by the centrifugal barrier. The quantal rate coefficient for temperatures from 40 to 1900 K has been computed using the Breit–Wigner theory to account for the resonances. Comparison with the results obtained by Singh and Andreazza [Astrophys. J.537, 261 (2000)] shows that the semiclassical method, which completely omits the shape resonances, is accurate to within 25% above room temperature. At lower temperatures the contribution from the shape resonances to the radiative association rate is more significant.

  • 49.
    Anttila, Liisa J.
    et al.
    Department of Chemistry—Ångström Laboratory, Uppsala University.
    Ghamgosar, Pedram
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Maji, Somnath
    Department of Chemistry—Ångström Laboratory, Uppsala University.
    Tian, Haining
    Department of Chemistry—Ångström Laboratory, Uppsala University.
    Ott, Sascha
    Department of Chemistry—Ångström Laboratory, Uppsala University.
    Hammarström, Leif
    Department of Chemistry—Ångström Laboratory, Uppsala University.
    Dynamics and Photochemical H-2 Evolution of Dye-NiO Photocathodes with a Biomimetic FeFe-Catalyst2016Ingår i: ACS Energy Letters, ISSN 2380-8195, Vol. 1, nr 6, s. 1106-1111Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mesoporous NiO films were cosensitized with a coumarin 343 dye and a proton reduction catalyst of the [Fe-2(CO)(6)(bdt)] (bdt = benzene-1,2-dithiolate) family. Femtosecond ultraviolet visible transient absorption experiments directly demonstrated subpicosecond hole injection into NiO from excited dyes followed by rapid (t(50%) similar to 6 ps) reduction of the catalyst on the surface with similar to 70% yield. The reduced catalyst was long-lived (2 mu s to 20 ms), which may allow protonation and a second reduction step of the catalyst to occur. A photo electrochemical device based on this photocathode produced H-2 with a Faradaic efficiency of similar to 50%. Fourier transform infrared spectroscopy and gas chromatography experiments demonstrated that the observed device deterioration with time was mainly due to catalyst degradation and desorption from the NiO surface. The insights gained from these mechanistic studies, regarding development of dye-catalyst cosensitized photocathodes, are discussed.

  • 50.
    Antzutkin, Oleg
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Norlin, N.
    Hellberg, M.
    Eriksson, P.
    Almqvist, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Leapman, R.D.
    Tycko, R.
    Petkova, A.T.
    Toth, I.
    Howes, A.P.
    Dupree, R.
    Binding of Aluminium(III)-Citrate Complexes, [Al3(H-1Cit)3(OH)]-4 and [Al3(H-1Cit)3(OH)4]-7, to Alzheimer's A-beta(1-40) Peptides: In situ Atomic Force, Electron Microscopy and Solid State 13C and 27Al NMR Studies2005Ingår i: Sixth Keele Meeting on Aluminium: Aluminium Lithosphere to Biosphere (and Back), Centro de Estudos do Ambiente e Mar, Universidade de Aveiro , 2005, s. 16-Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    It is believed that Alzheimer's disease (AD) amyloid-β-peptide (Aβ) deposits contribute directly to the disease's progressive neurodegeneration. Aggregation cascade for Aβ peptides, its relevance to neurotoxicity in the course of AD, various factors modulating Aβ aggregation kinetics and experimental methods useful for these studies were recently discussed [1]. Al(III), Zn(II), Cu(II) and Fe(III) ions are often colocalized at the center of the core of Alzheimer's amyloid plaques [2] and are suggested to promote aggregation of physiological concentrations of Aβ [3]. It has also been suggested that Al can block calcium permeable putative Aβ-peptide channels in bilayer membranes [4]. Therefore studies of complexation of metal ions with Aβ-oligomers and fibrils are important in the search for the causes of and potential treatments for AD.We studied effects of highly soluble and biologically relevant aluminium(III)-citrate compounds, [Al3(H-1Cit)3(OH)]-4 and [Al3(H-1Cit)3(OH)4]-7, on the fibrillogenesis of Aβ(1-40). All resonances in 156.37 MHz 27Al and 90.52 MHz 13C MAS NMR spectra of powder Al(III)-citrate complexes were assigned. 27Al MAS NMR of dialysed samples of Aβ(1-40) co-incubated with the Al(III)-citrate complexes at different concentrations in TRIS buffer solutions, pH 7.4, shows that Al(III)-citrates bind to Aβ(1-40) as [Al3(H-1Cit)3(OH)]-4 and either accelerate ([Al3(H-1Cit)3(OH)]-4 complex) or retard ([Al3(H-1Cit)3(OH)4]-7 compound) aggregation of Aβ(1-40) as revealed by AFM. [1] ON Antzutkin, Magn. Reson. Chem. 42 (2004) 231; [2] MA Lovell et al., J. Neurol. Sci. 158 (1998) 47; Ch Exley et al., Al and Alzheimer's disease, Ch Exley (Ed)1998) 47; Ch Exley , Ch Exley (Ed) Elsevier Science, 2001, 421; [3] PW Mantyh et al., J. Neurochem. 61 (1993) 1171; [4] N Arispe et al, PNAS 90 (1993) 567.

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