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  • 1.
    Abbas, Syed Adeel
    et al.
    Center for High Energy Physics, University of the Punjab, Quaid-e-Azam Campus, 54590 Lahore, Pakistan.
    Mahmood, I.
    Center for High Energy Physics, University of the Punjab, Quaid-e-Azam Campus, 54590 Lahore, Pakistan.
    Sajjad, Muhammad
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Noor, N.A.
    Department of Physics, RIPHAH International University, Campus Lahore, Pakistan.
    Mahmood, Q.
    Department of Physics, College of Science, Imam Abdulrahman Bin Faisal University, P O Box 1982, 31441 Dammam, Saudi Arabia.
    Naeem, M.A.
    Chemical Engineering Department, University of the Punjab, Lahore 54000, Pakistan.
    Mahmood, Asif
    College of Engineering Chemical Engineering Department King Saud University Riyadh, Saudi Arabia.
    Ramay, Shahid M.
    Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.
    Spinel-type Na2MoO4 and Na2WO4 as promising optoelectronic materials: First-principle DFT calculations2020Inngår i: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 538, artikkel-id 110902Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mechanical, thermodynamic, electronic, and optical properties of Na2MoO4 (NMO) and Na2WO4 (NWO) spinels are elaborated by density functional theory (DFT) based full potential augmented plane wave method (FP-LAPW + lo). Our optimized lattice constants for the studied spinels are in good agreement with that obtained experimentally. The enthalpy of formation ensures the thermodynamic stability of NMO and NWO in the cubic phase. The Born mechanical stability criteria guarantees their mechanical stability, while Poisson ratio (ν) and Pugh's ratio (B/G) infer their brittle behavior. The Debye temperature (θD) is significant for NMO than NWO. The wide bandgap of 3.5 eV for NMO and 4.4 eV for NWO show the maximum absorption in the ultraviolet region that increases their importance for optoelectronic applications. The optical properties are explained in term of dielectric constant, refractive index, absorption of light, reflection, and optical loss factor.

  • 2.
    Abdullha, Khalid A.
    et al.
    Department of Civil Engineering, College of Engineering, Mosul University, Mosul, Iraq.
    Abdullha, Aziz I.
    Department of Civil Engineering, College of Engineering, Tikrit University, Tikrit, Iraq.
    Abdul-Razzak, Ayad A.
    Department of Civil Engineering, College of Engineering, Mosul University, Mosul, Iraq.
    Al-Gburi, Majid
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Mechanical properties, thermal and chemical effect of polymer cotton bars reinforced with carbon / glass fiber2022Inngår i: Australian Journal of Mechanical Engineering, ISSN 1448-4846Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many researchers are interested in using natural fibres to treat due to recent advancements in polymer characteristics. The mechanical properties of three types of bars are studied in this paper: Cotton Fibre-Reinforced Polymer bars, Cotton/Carbon Fibre-Reinforced Polymer bars, and Cotton/Glass Fibre-Reinforced Polymer bars. The goal of the paper was to create low-cost bars with comparable mechanical performance and corrosion resistance to steel reinforcement. The bars were made using two methods: fibres immersed in polymer and fibres coated with polymer by repeated tension and relaxation of fibres. The second method produced better results in terms of the tensile strength of Cot.CFRP, Cot.GFRP, and Cot.FRP bars, which were 688, 477, and 284 MPa, respectively, and the stress–strain curve revealed brittle behaviour for all bars and modulus of elasticity of 43, 31 and 22 GPa. When sand was put on the bar’s surface, the bars demonstrated a good connection with the concrete. It also showed good resistance to moisture, alkaline solutions and acids, as well as heat resistance at temperatures below 200°C.

  • 3.
    Abel, Martin
    et al.
    Department of Physics, University of Texas, Austin, TX 78712, United States.
    Frommhold, Lothar
    Department of Physics, University of Texas, Austin, TX 78712, United States.
    Gustafsson, Magnus
    Department of Chemistry, University of Gothenburg, SE 412 96 Gothenburg, Sweden.
    Collision-induced absorption at wavelengths near 5 μm by dense hydrogen gas2009Inngår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 131, nr 18, artikkel-id 181102Artikkel i tidsskrift (Fagfellevurdert)
  • 4.
    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 kelvin2010Inngår 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. 251-257Konferansepaper (Fagfellevurdert)
    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

  • 5.
    Adeel, Muhammad
    et al.
    Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, 30172, Venice-Mestre, Italy. Pathology Unit, Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, 33081, Aviano, Italy.
    Canzonieri, Vincenzo
    Pathology Unit, Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, 33081, Aviano, Italy. Department of Medical, Surgical and Health Sciences, University of Trieste, 34127, Trieste, Italy.
    Daniele, Salvatore
    Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, 30172, Venice-Mestre, Italy.
    Vomiero, Alberto
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, 30172, Venice-Mestre, Italy.
    Rizzolio, Flavio
    Department of Molecular Sciences and Nanosystems, Ca’Foscari University of Venice, 30172, Venice-Mestre, Italy. Pathology Unit, Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, 33081, Aviano, Italy.
    Rahman, Md. Mahbubur
    Department of Energy and Materials, Konkuk University, Chungju, 27478, Republic of Korea.
    2D metal azolate framework as nanozyme for amperometric detection of glucose at physiological pH and alkaline medium2021Inngår i: Microchimica Acta, ISSN 0026-3672, E-ISSN 1436-5073, Vol. 188, nr 3, artikkel-id 77Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The synthesis of Co-based two-dimensional (2D) metal azolate framework nanosheets (MAF-5-CoII NS) is described using a simple hydrothermal method. The product was isostructural to MAF-5 (Zn). The as-prepared MAF-5-CoII NS exhibited high surface area (1155 m2/g), purity, and crystallinity. The MAF-5-CoII NS–modified screen-printed electrode (MAF-5-CoII NS/SPE) was used for nonenzymatic detection of glucose in diluted human blood plasma (BP) samples with phosphate buffer saline (PBS, pH 7.4) and NaOH (0.1 M, pH 13.0) solutions. The MAF-5-CoII NS nanozyme displayed good redox activity in both neutral and alkaline media with the formation of CoII/CoIII redox pair, which induced the catalytic oxidation of glucose. Under the optimized detection potential, the sensor presented a chronoamperometric current response for the oxidation of glucose with two wide concentration ranges in PBS-diluted (62.80 to 180 μM and 305 to 8055 μM) and NaOH-diluted (58.90 to 117.6 μM and 180 to 10,055 μM) BP samples, which were within the limit of blood glucose levels of diabetic patients before (4.4–7.2 mM) and after (10 mM) meals (recommended by the American Diabetes Association). The sensor has a limit of detection of ca. 0.25 and 0.05 μM, respectively, and maximum sensitivity of ca. 36.55 and 1361.65 mA/cm2/mM, respectively, in PBS- and NaOH-diluted BP samples. The sensor also displayed excellent stability in the neutral and alkaline media due to the existence of hydrophobic linkers (2-ethyl imidazole) in the MAF-5-CoII NS, good repeatability and reproducibility, and interference-free signals. Thus, MAF-5-CoII NS is a promising nanozyme for the development of the disposable type of sensor for glucose detection in human body fluids.

  • 6.
    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 review2017Inngår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 76, s. 1301-1313Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 7.
    Aftab, Umair
    et al.
    Department of Metallurgy and Materials Engineering, Mehran University of Engineering and Technology, Jamshoro, Sindh, 76080, Pakistan.
    Tahira, Aneela
    Department of Science and Technology, Campus Norrköping, Linköping University, Norrköping, SE-60174, Sweden.
    Gradone, Alessandro
    CNR-IMM, Via Piero Gobetti 101, Bologna, 40129, Italy. Chemistry Department “G.Ciamician”, University of Bologna, Bologna, 40126, Italy.
    Morandi, Vittorio
    CNR-IMM, Via Piero Gobetti 101, Bologna, 40129, Italy.
    Abro, Muhammad Ishaq
    Department of Metallurgy and Materials Engineering, Mehran University of Engineering and Technology, Jamshoro, Sindh, 76080, Pakistan.
    Baloch, Muhammad Moazam
    Department of Metallurgy and Materials Engineering, Mehran University of Engineering and Technology, Jamshoro, Sindh, 76080, Pakistan.
    Bhatti, Adeel Liaquat
    Institute of Physics University of Sindh, Jamshoro, Sindh, 76080, Pakistan.
    Nafady, Ayman
    Department of Chemistry, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.
    Vomiero, Alberto
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, Venezia, Mestre, 30172, Italy.
    Ibupoto, Zafar Hussain
    Dr. M.A Kazi Institute of Chemistry University of Sindh, Jamshoro, Sindh, 76080 Pakistan.
    Two step synthesis of TiO2–Co3O4 composite for efficient oxygen evolution reaction2021Inngår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 46, nr 13, s. 9110-9122Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For an active hydrogen gas generation through water dissociation, the sluggish oxygen evolution reaction (OER) kinetics due to large overpotential is a main hindrance. Herein, a simple approach is used to produce composite material based on TiO2/Co3O4 for efficient OER and overpotential is linearly reduced with increasing amount of TiO2. The scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) investigations reveal the wire like morphology of composite materials, formed by the self-assembly of nanoparticles. The titania nanoparticles were homogenously distributed on the larger Co3O4 nanoparticles. The powder x-ray diffraction revealed a tetragonal phase of TiO2 and the cubic phase of Co3O4 in the composite materials. Composite samples with increasing TiO2 content were obtained (18%, 33%, 41% and 65% wt.). Among the composites, cobalt oxide-titanium oxide with the highest TiO2 content (CT-20) possesses the lowest overpotential for OER with a Tafel slope of 60 mV dec−1 and an exchange current density of 2.98 × 10−3A/cm2. The CT-20 is highly durable for 45 h at different current densities of 10, 20 and 30 mA/cm2. Electrochemical impedance spectroscopy (EIS) confirmed the fast charge transport for the CT-20 sample, which potentially accelerated the OER kinetics. These results based on a two-step methodology for the synthesis of TiO2/Co3O4 material can be useful and interesting for various energy storage and energy conversion systems.

  • 8.
    Ahdikari, Rajesh
    et al.
    Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel-Boulet, Varennes, QC J3X1S2, Canada.
    Jin, Lei
    Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel-Boulet, Varennes, QC J3X1S2, Canada.
    Navarro-Pardo, Fabola
    Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel-Boulet, Varennes, QC J3X1S2, Canada.
    Benetti, Daniele
    Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel-Boulet, Varennes, QC J3X1S2, Canada.
    AlOtaibi, Bandar
    Dept. of Electrical and Computer Eng., McGill University, 3480 Univ. Str. W, Montreal, QC H3A 0E9, Canada.
    Vanka, Srinivas
    Dept. of Electrical and Computer Eng., McGill University, 3480 Univ. Str. W, Montreal, QC H3A 0E9, Canada.
    Zhao, Haiguang
    Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel-Boulet, Varennes, QC J3X1S2, Canada.
    Mi, Zetian
    Dept. of Electrical and Computer Eng., McGill University, 3480 Univ. Str. W, Montreal, QC H3A 0E9, Canada.
    Vomiero, Alberto
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel-Boulet, Varennes, QC J3X1S2, Canada.
    Rosei, Frederico
    Centre for Energy, Materials and Telecommunications, Institut National de la Recherche Scientifique, 1650 Boul. Lionel-Boulet, Varennes, QC J3X1S2, Canada; Institute for Fundamental and Frontier Science, University of Electronic Science and Technology of China, Chengdu, PR China.
    High Efficiency, Pt-free Photoelectrochemical Cells for Solar Hydrogen Generation based on “Giant” Quantum Dots2016Inngår i: Nano Energy, ISSN 2211-2855, Vol. 27, s. 265-274Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 9. 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 pressure1997Inngår 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 , 1997Konferansepaper (Fagfellevurdert)
  • 10. Aleksandrovski, A. N.
    et al.
    Kir'yanova, E. A.
    Manzheli, V. G.
    Soldatov, Alexander
    Tolkachev, A. M.
    Anomalies of the plastic deformation of solid parahydrogen1987Inngår i: Soviet Journal of Low Temperature Physics, ISSN 0360-0335, Vol. 13, nr 10, s. 623-624Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 11. 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 temperatures1997Inngår i: Low temperature physics (Woodbury, N.Y., Print), ISSN 1063-777X, E-ISSN 1090-6517, Vol. 23, nr 11, s. 943-946Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 12. Aleksandrovskii, A. N.
    et al.
    Palei, V. V.
    Soldatov, Alexander
    Parbuzin, V. S.
    Thermal expansion of solid deuterohydrogen at helium temperatures1990Inngår i: Soviet Journal of Low Temperature Physics, ISSN 0360-0335, Vol. 16, nr 11, s. 784-785Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 13. Aleksandrovskii, A. N.
    et al.
    Soldatov, Alexander
    Manzhelii, V. G.
    Palei, V.V.
    Thermal expansion of solid parahydrogen at helium temperatures1989Inngår i: Soviet Journal of Low Temperature Physics, ISSN 0360-0335, Vol. 15, nr 8, s. 492-493Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 14.
    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 content2016Inngår i: Low temperature physics (Woodbury, N.Y., Print), ISSN 1063-777X, E-ISSN 1090-6517, Vol. 42, nr 6, s. 484-490Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 15. 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 temperatures2000Inngår i: Low temperature physics (Woodbury, N.Y., Print), ISSN 1063-777X, E-ISSN 1090-6517, Vol. 26, nr 1, s. 75-80Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 16.
    Allali, Naoual
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Covalent functionalization of carbon nanomaterials for bioelectrochemical applications2019Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

    Fulltekst (pdf)
    fulltext
  • 17.
    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 biomolecules2018Inngår i: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 9, s. 2750-2762Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 18.
    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 derivatives2013Inngår i: 2012 MRS Fall Meeting: Symposium YY – Low-Voltage Electron Microscopy and Spectroscopy for Materials Characterization, Cambridge University Press, 2013Konferansepaper (Fagfellevurdert)
    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.

  • 19.
    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 devices2012Inngår i: MRS Online Proceedings Library, Cambridge University Press, 2012Konferansepaper (Fagfellevurdert)
    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).

  • 20.
    Allali, Naoual
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564 CNRS–Université de Lorraine, 54602 Villers-les-Nancy, France; Laboratoire de Structure et Réactivité des Systèmes Moléculaires Complexes, UMR 7565 CNRS–Université de Lorraine, 54506 Vandoeuvre-les-Nancy, France.
    Urbanova, Veronika
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564 CNRS–Université de Lorraine, 54602 Villers-les-Nancy, France.
    Mamane, Victor
    Laboratoire de Structure et Réactivité des Systèmes Moléculaires Complexes, UMR 7565 CNRS–Université de Lorraine, 54506 Vandoeuvre-les-Nancy, France.
    Waldbock, Jeremy
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564 CNRS–Université de Lorraine, 54602 Villers-les-Nancy, France.
    Etienne, Mathieu
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564 CNRS–Université de Lorraine, 54602 Villers-les-Nancy, France.
    Mallet, Martine
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564 CNRS–Université de Lorraine, 54602 Villers-les-Nancy, France.
    Devaux, Xavier
    Insitut Jean Lamour, Department P2M, UMR 7198 CNRS–Université de Lorraine, Ecole des Mines, 54042 Nancy, France.
    Vigolo, Brigitte
    Insitut Jean Lamour, Department CP2S, UMR 7198 CNRS–Université de Lorraine, 54506 Vandoeuvre-les-Nancy, France.
    Fort, Yves
    Laboratoire de Structure et Réactivité des Systèmes Moléculaires Complexes, UMR 7565 CNRS–Université de Lorraine, 54506 Vandoeuvre-les-Nancy, France.
    Walcarius, Alain
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564 CNRS–Université de Lorraine, 54602 Villers-les-Nancy, France.
    Noël, Maxime
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Soldatov, Alexander V.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Department of Physics, Harvard University, Cambridge, MA 02138, USA.
    McRae, Edward
    Insitut Jean Lamour, Department CP2S, UMR 7198 CNRS–Université de Lorraine, 54506 Vandoeuvre-les-Nancy, France.
    Dossot, Manuel
    Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, UMR 7564 CNRS–Université de Lorraine, 54602 Villers-les-Nancy, France.
    Covalent functionalization of few-wall carbon nanotubes by ferrocene derivatives for bioelectrochemical devices2012Inngår i: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 249, nr 12, s. 2349-2352Artikkel i tidsskrift (Fagfellevurdert)
    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).

  • 21.
    Almqvist, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Fractal analysis of scanning probe microscopy images1996Inngår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 355, nr 1-3, s. 221-228Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 22.
    Almqvist, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Scanning probe microscopy: Applications1994Licentiatavhandling, med artikler (Annet vitenskapelig)
    Fulltekst (pdf)
    fulltext
  • 23.
    Almqvist, Nils
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Studies of plasma-facing materials and macromolecules using scanning probe microscopy1995Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

    Fulltekst (pdf)
    FULLTEXT01
  • 24.
    Almqvist, Nils
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Backman, Lars
    Department of Biochemistry, University of Umeå, Umeå, Sweden.
    Fredriksson, Sverker
    Luleå tekniska universitet.
    Imaging human erythrocyte spectrin with atomic force microscopy1994Inngår i: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 25, nr 3, s. 227-232Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 25.
    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 properties2004Inngår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 86, nr 3, s. 1753-1762Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 26.
    Almqvist, Nils
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Department of Physics, University of California, CA, United States;Marine Science Institute, University of California, Santa Barbara, CA, United States.
    Delamo, Y.
    Neuroscience Research Institute, University of California, Santa Barbara, CA, United States; Department of Physics and Astronomy, University of Leeds, Leeds, United Kingdom.
    Smith, B. L.
    Luleå tekniska universitet.
    Thomson, N. H.
    Luleå tekniska universitet. Laboratoire d'Océanographie Biologique (LOB), Arcachon, France.
    Bartholdson, Å.
    Luleå tekniska universitet. Department of Physics and Astronomy, University of Leeds, Leeds, United Kingdom.
    Lal, R.
    Marine Science Institute, University of California, Santa Barbara, CA, United States.
    Brzezinski, M.
    Neuroscience Research Institute, University of California, Santa Barbara, CA, United States.
    Hansma, P. K.
    Luleå tekniska universitet.
    Micromechanical and structural properties of a pennate diatom investigated by atomic force microscopy2001Inngår i: Journal of Microscopy, ISSN 0022-2720, E-ISSN 1365-2818, Vol. 202, nr 3, s. 518-532Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 27.
    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 plasma1994Inngår i: Book of abstracts: Microprobe Symposium, Vadstena, April 25-26, 1994, 1994Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 28.
    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 microscopy2000Inngår i: Abstract book Nordic-Baltic SPM Workshop, 2000: abstract #1, 2000Konferansepaper (Fagfellevurdert)
    Fulltekst (pdf)
    fulltext
  • 29.
    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 microscopy1995Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 201, nr 1-2, s. 277-285Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 30.
    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 plasma1995Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 220-222, nr 1-3, s. 917-921Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 31.
    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 composites1995Inngår 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. 361-368Konferansepaper (Fagfellevurdert)
    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.

  • 32.
    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 microscopy1995Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 270, nr 1-2, s. 426-430Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 33.
    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 materials1999Inngår i: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 7, nr 1, s. 37-43Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 34.
    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 deposition2019Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 692, artikkel-id 137631Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 35.
    Alvi, Sajid
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Jarzabek, Dariusz M.
    Department of Mechanics of Materials (ZMM), Institute of Fundamental Technological Research, Polish Academy of Sciences, 02-106 Warsaw, Poland.
    Gilzad Kohan, Mojtaba
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Hedman, Daniel
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Jenczyk, Piotr
    Department of Mechanics of Materials (ZMM), Institute of Fundamental Technological Research, Polish Academy of Sciences, 02-106 Warsaw, Poland.
    Natile, Marta Maria
    CNR—Institute of Condensed Matter Chemistry and Technologies for Energy (ICMATE), I-16149 Genoa, Italy. Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.
    Vomiero, Alberto
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Akhtar, Farid
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Synthesis and Mechanical Characterization of a CuMoTaWV High-Entropy Film by Magnetron Sputtering2020Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 12, nr 18, s. 21070-21079Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Development of high-entropy alloy (HEA) films is a promising and cost-effective way to incorporate these materials of superior properties in harsh environments. In this work, a refractory high-entropy alloy (RHEA) film of equimolar CuMoTaWV was deposited on silicon and 304 stainless-steel substrates using DC-magnetron sputtering. A sputtering target was developed by partial sintering of an equimolar powder mixture of Cu, Mo, Ta, W, and V using spark plasma sintering. The target was used to sputter a nanocrystalline RHEA film with a thickness of ∼900 nm and an average grain size of 18 nm. X-ray diffraction of the film revealed a body-centered cubic solid solution with preferred orientation in the (110) directional plane. The nanocrystalline nature of the RHEA film resulted in a hardness of 19 ± 2.3 GPa and an elastic modulus of 259 ± 19.2 GPa. A high compressive strength of 10 ± 0.8 GPa was obtained in nanopillar compression due to solid solution hardening and grain boundary strengthening. The adhesion between the RHEA film and 304 stainless-steel substrates was increased on annealing. For the wear test against the E52100 alloy steel (Grade 25, 700–880 HV) at 1 N load, the RHEA film showed an average coefficient of friction (COF) and wear rate of 0.25 (RT) and 1.5 (300 °C), and 6.4 × 10–6 mm3/N m (RT) and 2.5 × 10–5 mm3/N m (300 °C), respectively. The COF was found to be 2 times lower at RT and wear rate 102 times lower at RT and 300 °C than those of 304 stainless steel. This study may lead to the processing of high-entropy alloy films for large-scale industrial applications.

  • 36.
    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 nanoneedles2019Inngår i: RSC Advances, E-ISSN 2046-2069, Vol. 9, nr 25, s. 14443-14451Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 37.
    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 applications2019Inngår i: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 11, s. 3578-3583Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 38.
    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, Sindh Pakistan.
    Tahira, Aneela
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Solangi, Amber R.
    National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro, Pakistan.
    Mazzaro, Raffaello
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Institute for Microelectronics and Microsystems, National Research Council, Bologna, Italy.
    Ibupoto, Zafar Hussain
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Institute of Chemistry, University of Sindh, Jamshoro, Sindh Pakistan.
    Fatima, Almas
    National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro, Pakistan.
    Vomiero, Alberto
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, Italy.
    Functional Nickel Oxide Nanostructures for Ethanol Oxidation in Alkaline Media2020Inngår i: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 32, nr 5, s. 1052-1059Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nickel oxide (NiO) nanostructures are employed in the basic medium for the oxidation of ethanol. A variety of NiO nanostructures are synthesized by wet chemical growth method, using different hydroxide (OH−) ion sources, particularly from ammonia, hexamethylenetetramine, urea and sodium hydroxide. The use of urea as (OH−) ion source results in flower‐like NiO structures composed by extremely thin nanowalls (thickness lower than 10 nm,), which demonstrated to be the most active for ethanol oxidation. All the samples exhibit NiO cubic phase, and no other impurity was detected. The cyclic voltammetry (CV) curves of NiO nanostructures were found linear over the concentration range 0.1–3.5 mM (R2=0.99) of ethanol, with the limit of detection estimated to be 0.013 mM for ethanol. The NiO nanostructures exhibit a selective signal towards ethanol oxidation in the presence of different members of alcohol family. The proposed NiO nanostructures showed a significant practicality for the reproducible and sensitive determination of ethanol from brandy, whisky, mixture of brandy and rum, and vodka samples. The nanomaterial was used as a surface modifying agent for the glassy carbon electrode and it showed a stable electro‐oxidation activity for the ethanol for 16 days. These findings indicate that the presented NiO nanomaterial can be applied in place of noble metals for ethanol sensing and other environmental applications (like fuel cells).

  • 39.
    Andersson, L.C.
    et al.
    Luleå tekniska universitet.
    Hauska, Hans
    Luleå tekniska universitet.
    Lineament mapping in Northern Sweden from Landsat images using orthogonal image transforms1980Inngår 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. 147-157Konferansepaper (Fagfellevurdert)
    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

  • 40.
    Andersson, L.C.
    et al.
    Luleå tekniska universitet.
    Hauska, Hans
    Luleå tekniska universitet.
    Lineaments analysis using global and local Fourier transforms1983Inngår 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. 63-69Konferansepaper (Fagfellevurdert)
  • 41.
    Andersson, O.
    et al.
    Department of Experimental Physics, Umeå University, S-90187 Umeå, Sweden.
    Soldatov, Alexander
    Department of Experimental Physics, Umeå University, S-90187 Umeå, Sweden.
    Sundqvist, B.
    Department of Experimental Physics, Umeå University, S-90187 Umeå, Sweden.
    Thermal conductivity of C60 at pressures up to 1 GPa and temperatures in the 50-300 K range1996Inngår i: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 54, nr 5, s. 3093-3100Artikkel i tidsskrift (Fagfellevurdert)
  • 42. Andersson, O.
    et al.
    Soldatov, Alexander
    Sundqvist, B.
    Thermal conductivity of C60 under high pressure1995Inngår 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. 549-554Konferansepaper (Fagfellevurdert)
  • 43. Andersson, O.
    et al.
    Soldatov, Alexander
    Sundqvist, Bertil
    Reorientational relaxation in C60 following a pressure induced change in the pentagon/hexagon equilibrium ratio1995Inngår i: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 206, nr 3-4, s. 260-264Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 44. 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 space1997Inngår 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, 1997Konferansepaper (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    FULLTEXT01
  • 45.
    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 X2000Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 13, nr 3, s. 519-526Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 46. 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 measurements1996Inngår i: Proceedings of International Workshop on Deep Inelastic Scattering and Related Phenomena, DIS 96, 1996, s. 583-589Konferansepaper (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    FULLTEXT01
  • 47. 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 scattering1997Inngår i: SPIN 96: proceedings; September 10-14, 1996, Amsterdam, the Netherlands, Singapore: World Scientific Publishing Co Pte Ltd , 1997, s. 346-348Konferansepaper (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    FULLTEXT01
  • 48.
    Anselmino, Mauro
    Luleå tekniska universitet.
    Diquarks1992Rapport (Annet vitenskapelig)
  • 49.
    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 predictions1996Inngår i: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 54, nr 1, s. 828-837Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 50.
    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.
    Diquarks1993Inngår i: Reviews of Modern Physics, ISSN 0034-6861, E-ISSN 1539-0756, Vol. 65, nr 4, s. 1199-1233Artikkel i tidsskrift (Fagfellevurdert)
    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.

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