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  • 1. Aad, G
    et al.
    Jovicevic, Jelena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kuwertz, Emma
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Lund-Jensen, Bengt
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Morley, Anthony
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Zwalinski, L.
    et al.,
    Measurement of differential production cross-sections for a Z boson in association with b-jets in 7 TeV proton-proton collisions with the ATLAS detector2014In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 10, p. 141-Article in journal (Refereed)
    Abstract [en]

    Measurements of differential production cross-sections of a Z boson in association with b-jets in pp collisions at root s = 7 TeV are reported. The data analysed correspond to an integrated luminosity of 4.6 fb(-1) recorded with the ATLAS detector at the Large Hadron Collider. Particle-level cross-sections are determined for events with a Z boson decaying into an electron or muon pair, and containing b-jets. For events with at least one b-jet, the cross-section is presented as a function of the Z boson transverse momentum and rapidity, together with the inclusive b-jet cross-section as a function of b-jet transverse momentum, rapidity and angular separations between the b-jet and the Z boson. For events with at least two b-jets, the cross-section is determined as a function of the invariant mass and angular separation of the two highest transverse momentum b-jets, and as a function of the Z boson transverse momentum and rapidity. Results are compared to leading-order and next-to-leading-order perturbative QCD calculations.

  • 2. Aad, G
    et al.
    Jovicevic, Jelena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kuwertz, Emma
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Lund-Jensen, Bengt
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Morley, Anthony
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Zwalinski, L.
    et al.,
    Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at TeV with ATLAS2014In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 9, p. 1-61Article in journal (Refereed)
    Abstract [en]

    Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of TeV. The analysis is performed in the H -> gamma gamma decay channel using 20.3 fb(-1) of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp -> H -> gamma gamma fiducial cross section is measured to be 43.2 +/- 9.4(stat.) (-aEuro parts per thousand 2.9) (+ 3.2) (syst.) +/- 1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations.

  • 3. Aad, G
    et al.
    Jovicevic, Jelena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Kuwertz, Emma
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Morley, Anthony
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Zwalinski, L.
    et al.,
    Search for Scalar Diphoton Resonances in the Mass Range 65-600 GeV with the ATLAS Detector in pp Collision Data at root s=8 TeV2014In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 113, no 17Article in journal (Refereed)
    Abstract [en]

    A search for scalar particles decaying via narrow resonances into two photons in the mass range 65-600 GeV is performed using 20.3 fb(-1) of root s = 8 TeV pp collision data collected with the ATLAS detector at the Large Hadron Collider. The recently discovered Higgs boson is treated as a background. No significant evidence for an additional signal is observed. The results are presented as limits at the 95% confidence level on the production cross section of a scalar boson times branching ratio into two photons, in a fiducial volume where the reconstruction efficiency is approximately independent of the event topology. The upper limits set extend over a considerably wider mass range than previous searches.

  • 4. Abat, E.
    et al.
    Grahan, Karl-Johan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Lafaye, Remi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Lund-Jensen, Bengt
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Zhou, N.
    et, al
    Photon reconstruction in the ATLAS Inner Detector and Liquid Argon Barrel Calorimeter at the 2004 Combined Test Beam2011In: Journal of Instrumentation, E-ISSN 1748-0221, Vol. 6Article in journal (Refereed)
    Abstract [en]

    The reconstruction of photons in the ATLAS detector is studied with data taken during the 2004 Combined Test Beam, where a full slice of the ATLAS detector was exposed to beams of particles of known energy at the CERN SPS. The results presented show significant differences in the longitudinal development of the electromagnetic shower between converted and unconverted photons as well as in the total measured energy. The potential to use the reconstructed converted photons as a means to precisely map the material of the tracker in front of the electromagnetic calorimeter is also considered. All results obtained are compared with a detailed Monte-Carlo simulation of the test-beam setup which is based on the same simulation and reconstruction tools as those used for the ATLAS detector itself.

  • 5. Abbas, Syed Sohail
    et al.
    Popov, Sergei Yu
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Compact Er 3+-doped ZBLAN green upconversion fibre laser2011In: World Academy of Science, Engineering and Technology: An International Journal of Science, Engineering and Technology, ISSN 2010-376X, Vol. 78, p. 756-758Article in journal (Refereed)
    Abstract [en]

    In this paper, a fibre laser at 546 nm has been studied for a signal power of -30 dB. Er 3+-doped ZBLAN fibre has been used by upconversion pumping of a 980 nm laser diode. Gain saturation effect has been investigated in detail. Laser performance has also been discussed. An efficiency of 35% has been calculated with a length of 5 mm fibre laser. Results show that Er 3+-doped ZBLAN is a promising candidate for optical amplification at 546 nm.

  • 6.
    Abergel, David
    et al.
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Edge, Jonathan M.
    Balatsky, Alexander V.
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    The role of spin-orbit coupling in topologically protected interface states in Dirac materials2014In: New Journal of Physics, E-ISSN 1367-2630, Vol. 16, p. 065012-Article in journal (Refereed)
    Abstract [en]

    We highlight the fact that two-dimensional (2D) materials with Dirac-like low energy band structures and spin-orbit coupling (SOC) will produce linearly dispersing topologically protected Jackiw-Rebbi modes at interfaces where the Dirac mass changes sign. These modes may support persistent spin or valley currents parallel to the interface, and the exact arrangement of such topologically protected currents depends crucially on the details of the SOC in the material. As examples, we discuss buckled 2D hexagonal lattices such as silicene or germanene, and transition metal dichalcogenides such as MoS2.

  • 7.
    Abramson, Nils H.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Metrology and Optics.
    Appearance of Objects at Relativistic Velocities, a Holographic Approach2010In: SEARCH FOR FUNDAMENTAL THEORY / [ed] Amoroso RL, Rowlands P, Jeffers S, MELVILLE, NY: AMER INST PHYSICS , 2010, Vol. 1316, p. 118-124Conference paper (Refereed)
    Abstract [en]

    A diagram borrowed from holographic interferometry has been applied to visualize phenomena in Special Relativity. It displays how a sphere of observation is by velocity elongated into an ellipsoid of observation and produces graphically all the well accepted equations of Einsteins Special Relativity. The Lorentz contraction, however, is explained as an elongation of the measuring rod, the meter, which by definition is based on either a specific number of wavelengths or the velocity of light multiplied by time. The diagram displays the total apparent object distortions including not only the Lorentz contraction but also larger apparent contractions and elongations caused by the classic Doppler Effect. The reasons of these deformations are the delays caused by variations in distance from observer to different parts of the moving object. In this paper we do not discuss the meaning of apparent, as compared to real, deformation.

  • 8.
    Abramson, Nils H.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Elliptic visualizing optical resolution and kinetic energy2017In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 56, no 5, p. 1413-1416Article in journal (Refereed)
    Abstract [en]

    Diffraction limited resolution as introduced by Abbe is well established, but interference limited resolution was not well known until holographic interferometry was introduced. The holodiagram is used to simplify holography and in a new way visualize the distribution, ratio, and relation among resolutions of different optical techniques, including relativistic phenomena. Resolution, when measured by optical methods based on the number of wavelengths of light, is defined in the following as the minimum distance between resolvable points, or the largest object needed to be resolved. Everywhere in the diagram this resolution is represented by two orthogonal diagonals of rhombs.

  • 9.
    Abramson, Nils H.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Metrology and Optics.
    Holodiagram: elliptic visualizing interferometry, relativity, and light-in-flight2014In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 53, no 11, p. 2398-2404Article in journal (Refereed)
    Abstract [en]

    In holographic interferometry, there is usually a static distance separating the point of illumination and the point of observation. In Special Relativity, this separation is dynamic and is caused by the velocity of the observer. The corrections needed to compensate for these separations are similar in the two fields. We use the ellipsoids of the holodiagram for measurement and in a graphic way to explain and evaluate optical resolution, gated viewing, radar, holography, three-dimensional interferometry, Special Relativity, and light-in-flight recordings. Lorentz contraction together with time dilation is explained as the result of the eccentricity of the measuring ellipsoid, caused by its velocity. The extremely thin ellipsoid of the very first light appears as a beam aimed directly at the observer, which might explain the wave or ray duality of light and entanglement. Finally, we introduce the concept of ellipsoids of observation.

  • 10.
    Abramson, Nils H.
    KTH, School of Industrial Engineering and Management (ITM).
    Holographic Metrology and Basic Physics2013In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 415, no 1, p. 012030-Article in journal (Refereed)
    Abstract [en]

    A short pulse of light is emitted from one point followed by a short observation from another point separated in space and time from the first. Even if space is full of scattering particles no sphere of expanding light is seen from outside by the observer, instead he finds himself inside an ellipsoid of light. We use this ellipsoid for measurement and in a graphic way to explain and evaluate optical resolution, gated viewing, radar, holography, 3-D interferometry and Special Relativity. In the later case the Lorentz Contraction together with the Time Dilation are explained as results of the eccentricity of the measuring ellipsoid, caused by its velocity. Finally, the extremely thin ellipsoid of the very first light appears as a beam aimed directly at the observer which might explain the wave or ray duality of light and entanglement.

  • 11.
    Abramson, Nils H.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Metrology and Optics.
    INSTANT RANDOM INFORMATION2010In: SEARCH FOR FUNDAMENTAL THEORY / [ed] Amoroso RL, Rowlands P, Jeffers S, MELVILLE, NY: AMER INST PHYSICS , 2010, Vol. 1316, p. 113-117Conference paper (Refereed)
    Abstract [en]

    Information is carried by matter or by energy and thus Einstein stated that "no information can travel faster than light." He also was very critical to the "Spooky action at distance" as described in Quantum Physics. However, many verified experiments have proven that the "Spooky actions" not only work at distance but also that they travel at a velocity faster than light, probably at infinite velocity. Examples are Young's fringes at low light levels or entanglements. My explanation is that this information is without energy. In the following I will refer to this spooky information as exformation, where "ex-" refers to existence, the information is not transported in any way, it simply exists. Thus Einstein might have been wrong when he stated that no information can travel faster than light. But he was is right in that no detectable information can travel faster than light. Phenomena connected to entanglement appear at first to be exceptions, but in those cases the information can not be reconstructed until energy is later sent in the form of correlation using ordinary information at the velocity of light. In entanglement we see that even if the exformation can not be detected directly because its luck of energy it still can influence what happens at random, bemuse in Quantum Physics there is by definition no energy difference between two states that happen randomly.

  • 12. Abrikosov, I. A.
    et al.
    Ponomareva, A. V.
    Barannikova, S. A.
    Hellman, O.
    Vekilova, O.Yu.
    Simak, S. I.
    Ruban, Andrei V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Multiscale approach to theoretical simulations of materials for nuclear energy applications: Fe-Cr and Zr-based alloys2013In: Advances in materials for nuclear energy: symposium held November 25-30, Boston, Massachusetts, U.S.A., Materials Research Society, 2013, p. 3-14Conference paper (Refereed)
    Abstract [en]

    We review basic ideas behind state-of-the-art techniques for first-principles theoretical simulations of the phase stabilities and properties of alloys. We concentrate on methods that allow for an efficient treatment of compositional and thermal disorder effects. In particular, we present novel approach to evaluate free energy for strongly anharmonic systems. Theoretical tools are then employed in studies of two materials systems relevant for nuclear energy applications: Fe-Cr and Zr-based alloys. In particular, we investigate the effect of hydrostatic pressure and multicomponent alloying on the mixing enthalpy of Fe-Cr alloys, and show that in the ferromagnetic state both of them reduce the alloy stability at low Cr concentration. For Zr-Nb alloys, we demonstrate how microscopic parameters calculated from first-principles can be used in higher-level models.

  • 13.
    Adler, Mark
    et al.
    Brandeis Univ, Dept Math, Waltham, MA 02453 USA..
    Johansson, Kurt
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    van Moerbeke, Pierre
    Univ Louvain, Dept Math, B-1348 Louvain, Belgium.;Brandeis Univ, Waltham, MA 02453 USA..
    Tilings of Non-convex Polygons, Skew-Young Tableaux and Determinantal Processes2018In: Communications in Mathematical Physics, ISSN 0010-3616, E-ISSN 1432-0916, Vol. 364, no 1, p. 287-342Article in journal (Refereed)
    Abstract [en]

    This paper studies random lozenge tilings of general non-convex polygonal regions. We show that the pairwise interaction of the non-convexities leads asymptotically to new kernels and thus to new statistics for the tiling fluctuations. The precise geometrical figure here consists of a hexagon with cuts along opposite edges. For this model, we take limits when the size of the hexagon and the cuts tend to infinity, while keeping certain geometric data fixed in order to guarantee sufficient interaction between the cuts in the limit. We show in this paper that the kernel for the finite tiling model can be expressed as a multiple integral, where the number of integrations is related to the fixed geometric data above. The limiting kernel is believed to be a universal master kernel.

  • 14. Adriani, O.
    et al.
    Barbarino, G. C.
    Bazilevskaya, G. A.
    Bellotti, R.
    Boezio, M.
    Bogomolov, E. A.
    Bongi, M.
    Bonvicini, V.
    Bottai, S.
    Bruno, A.
    Cafagna, F.
    Campana, D.
    Carbone, R.
    Carlson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova University Centre, Sweden.
    Casolino, M.
    Castellini, G.
    De Pascale, M. P.
    De Santis, C.
    De Simone, N.
    Di Felice, V.
    Formato, V.
    Galper, A. M.
    Giaccari, U.
    Karelin, A. V.
    Kheymits, M. D.
    Koldashov, S. V.
    Koldobskiy, S.
    Krut'kov, S. Yu.
    Kvashnin, A. N.
    Leonov, A.
    Malakhov, V.
    Marcelli, L.
    Martucci, M.
    Mayorov, A. G.
    Menn, W.
    Mikhailov, V. V.
    Mocchiutti, E.
    Monaco, A.
    Mori, N.
    Munini, Riccardo
    KTH, School of Engineering Sciences (SCI), Physics. INFN, Italy; AlbaNova University Centre, Sweden; University of Trieste, Italy.
    Nikonov, N.
    Osteria, G.
    Papini, P.
    Pearce, Mark
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova University Centre, Sweden.
    Picozza, P.
    Pizzolotto, C.
    Ricci, M.
    Ricciarini, S. B.
    Rossetto, Laura
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova University Centre, Sweden.
    Sarkar, R.
    Simon, M.
    Sparvoli, R.
    Spillantini, P.
    Stozhkov, Y. I.
    Vacchi, A.
    Vannuccini, E.
    Vasilyev, G. I.
    Voronov, S. A.
    Wu, Juan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. AlbaNova University Centre, Sweden; China University of Geosciences, China .
    Yurkin, Y. T.
    Zampa, G.
    Zampa, N.
    Zverev, V. G.
    The PAMELA Mission: Heralding a new era in precision cosmic ray physics2014In: Physics reports, ISSN 0370-1573, E-ISSN 1873-6270, Vol. 544, no 4, p. 323-370Article, review/survey (Refereed)
    Abstract [en]

    On the 15th of June 2006, the PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) satellite-borne experiment was launched onboard the Russian Resurs-DK1 satellite by a Soyuz rocket from the Baikonur space centre. The satellite was placed in a quasi-polar 70 degrees inclination orbit at an altitude varying between 350 km and 600 km. New results on the antiparticle component of the cosmic radiation were obtained. The positron energy spectrum and positron fraction were measured from 400 MeV up to 200 GeV revealing a positron excess over the predictions of commonly used propagation models. This can be interpreted either as evidence that the propagation models should be revised or in terms of dark matter annihilation or a pulsar contribution. The antiproton spectrum was measured over the energy range from 60 MeV to 350 GeV. The antiproton spectrum is consistent with secondary production and significantly constrains dark matter models. The energy spectra of protons and helium nuclei were measured up to 1.2 TV. The spectral shapes of these two species are different and cannot be described well by a single power law. For the First time the electron spectrum was measured up to 600 GeV complementing the information obtained from the positron data. Nuclear and isotopic composition was obtained with unprecedented precision. The variation of the low energy proton, electron and positron energy spectra was measured from July 2006 until December 2009 accurately sampling the unusual conditions of the most recent solar minimum activity period (2006-2009). Low energy particle spectra were accurately measured also for various solar events that occurred during the PAMELA mission. The Earth's magnetosphere was studied measuring the particle radiation in different regions of the magnetosphere. Energy spectra and composition of sub-cutoff and trapped particles were obtained. For the first time a belt of trapped antiprotons was detected in the South Atlantic Anomaly region. The flux was found to exceed that for galactic cosmic-ray antiprotons by three order of magnitude.

  • 15.
    Afonso, Marco Martins
    et al.
    Univ Porto, Fac Ciencias, Ctr Matemat, Rua Campo Alegre 687, P-4169007 Porto, Portugal..
    Mitra, Dhrubaditya
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Vincenzi, Dario
    Univ Cote dAzur, CNRS, LJAD, F-06100 Nice, France..
    Kazantsev dynamo in turbulent compressible flows2019In: Proceedings of the Royal Society. Mathematical, Physical and Engineering Sciences, ISSN 1364-5021, E-ISSN 1471-2946, Vol. 475, no 2223, article id 20180591Article in journal (Refereed)
    Abstract [en]

    We consider the kinematic fluctuation dynamo problem in a flow that is random, white-in-time, with both solenoidal and potential components. This model is a generalization of the well-studied Kazantsev model. If both the solenoidal and potential parts have the same scaling exponent, then, as the compressibility of the flow increases, the growth rate decreases but remains positive. If the scaling exponents for the solenoidal and potential parts differ, in particular if they correspond to typical Kolmogorov and Burgers values, we again find that an increase in compressibility slows down the growth rate but does not turn it off. The slow down is, however, weaker and the critical magnetic Reynolds number is lower than when both the solenoidal and potential components display the Kolmogorov scaling. Intriguingly, we find that there exist cases, when the potential part is smoother than the solenoidal part, for which an increase in compressibility increases the growth rate. We also find that the critical value of the scaling exponent above which a dynamo is seen is unity irrespective of the compressibility. Finally, we realize that the dimension d = 3 is special, as for all other values of d the critical exponent is higher and depends on the compressibility.

  • 16.
    Agrawal, Vipin
    et al.
    Nordita SU; Stockholm Univ, Roslagstullsbacken 23, S-10691 Stockholm, Sweden.;Stockholm Univ, Dept Phys, S-10691 Stockholm, Sweden..
    Mitra, Dhrubaditya
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Chaos and irreversibility of a flexible filament in periodically driven Stokes flow2022In: Physical review. E, ISSN 2470-0045, E-ISSN 2470-0053, Vol. 106, no 2, article id 025103Article in journal (Refereed)
    Abstract [en]

    The flow of Newtonian fluid at low Reynolds number is, in general, regular and time-reversible due to absence of nonlinear effects. For example, if the fluid is sheared by its boundary motion that is subsequently reversed, then all the fluid elements return to their initial positions. Consequently, mixing in microchannels happens solely due to molecular diffusion and is very slow. Here, we show, numerically, that the introduction of a single, freely floating, flexible filament in a time-periodic linear shear flow can break reversibility and give rise to chaos due to elastic nonlinearities, if the bending rigidity of the filament is within a carefully chosen range. Within this range, not only the shape of the filament is spatiotemporally chaotic, but also the flow is an efficient mixer. Overall, we find five dynamical phases: the shape of a stiff filament is time-invariant-either straight or buckled; it undergoes a period-two bifurcation as the filament is made softer; becomes spatiotemporally chaotic for even softer filaments but, surprisingly, the chaos is suppressed if bending rigidity is decreased further.

  • 17.
    Ahmadi, Sareh
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Agnarsson, Björn
    Bidermane, Ieva
    Wojek, Bastian M.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Noël, Quentin
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Sun, Chenghua
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Site-dependent charge transfer at the Pt(111)-ZnPc interface and the effect of iodine2014In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 140, no 17, p. 174702-Article in journal (Refereed)
    Abstract [en]

    The electronic structure of ZnPc, from sub-monolayers to thick films, on bare and iodated Pt(111) is studied by means of X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and scanning tunneling microscopy. Our results suggest that at low coverage ZnPc lies almost parallel to the Pt(111) substrate, in a non-planar configuration induced by Zn-Pt attraction, leading to an inhomogeneous charge distribution within the molecule and an inhomogeneous charge transfer to the molecule. ZnPc does not form a complete monolayer on the Pt surface, due to a surface-mediated intermolecular repulsion. At higher coverage ZnPc adopts a tilted geometry, due to a reduced molecule-substrate interaction. Our photoemission results illustrate that ZnPc is practically decoupled from Pt, already from the second layer. Pre-deposition of iodine on Pt hinders the Zn-Pt attraction, leading to a non-distorted first layer ZnPc in contact with Pt(111)-I(root 3x root 3) or Pt(111)-I(root 7x root 7), and a more homogeneous charge distribution and charge transfer at the interface. On increased ZnPc thickness iodine is dissolved in the organic film where it acts as an electron acceptor dopant.

  • 18.
    Ahmadi, Sareh
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Agnarsson, Björn
    Bidermane, Leva
    Wojek, Bastian M.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Noël, Quentin
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Sun, Chenghua
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Effect of the iodineon the site-dependent charge transfer at the Pt(111)-ZnPc interfaceManuscript (preprint) (Other academic)
  • 19.
    Ahmadi, Sareh
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Bidermane, Leva
    Noël, Quentin
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Sun, Chenghua
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Dissociative bonding of 4-tert-butyl pyridine to Pt(111) and surface passivation by iodineManuscript (preprint) (Other academic)
  • 20.
    Ahmadi, Sareh
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Shariati, M. Nina
    Yu, Shun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Molecular layers of ZnPc and FePc on Au(111) surface: Charge transfer and chemical interaction2012In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 137, no 8, p. 084705-Article in journal (Refereed)
    Abstract [en]

    We have studied zinc phthalocyanine (ZnPc) and iron phthalocyanine (FePc) thick films and monolayers on Au(111) using photoelectron spectroscopy and x-ray absorption spectroscopy. Both molecules are adsorbed flat on the surface at monolayer. ZnPc keeps this orientation in all investigated coverages, whereas FePc molecules stand up in the thick film. The stronger inter-molecular interaction of FePc molecules leads to change of orientation, as well as higher conductivity in FePc layer in comparison with ZnPc, which is reflected in thickness-dependent differences in core-level shifts. Work function changes indicate that both molecules donate charge to Au; through the pi-system. However, the Fe3d derived lowest unoccupied molecular orbital receives charge from the substrate when forming an interface state at the Fermi level. Thus, the central atom plays an important role in mediating the charge, but the charge transfer as a whole is a balance between the two different charge transfer channels; pi-system and the central atom.

  • 21.
    Ahmadi, Sareh
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Yu, Shun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Soldemo, Markus
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Sun, Chenghua
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Reduced Au-MPc hole injection barrier by an intermediate iodine layerManuscript (preprint) (Other academic)
  • 22.
    Ahmadi, Sareh
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Yu, Shun
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Soldemo, Markus
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Zuleta, Marcelo
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Palmgren, Pål
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Charge transfer and band bending on TiO2(110)-MgPcManuscript (preprint) (Other academic)
  • 23. Ahmed, T.
    et al.
    Albers, R. C.
    Balatsky, Alexander V.
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Friedrich, C.
    Zhu, J. -X
    G W quasiparticle calculations with spin-orbit coupling for the light actinides2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 89, no 3, p. 035104-Article in journal (Refereed)
    Abstract [en]

    We report on the importance of GW self-energy corrections for the electronic structure of light actinides in the weak-to-intermediate coupling regime. Our study is based on calculations of the band structure and total density of states of Np, U, and Pu using a one-shot GW approximation that includes spin-orbit coupling within a full potential LAPW framework. We also present RPA screened effective Coulomb interactions for the f-electron orbitals for different lattice constants, and show that there is an increased contribution from electron-electron correlation in these systems for expanded lattices. We find a significant amount of electronic correlation in these highly localized electronic systems.

  • 24.
    Ai, Yuejie
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Tian, Guangjun
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Liao, Rongzhen
    Stockholm University.
    Zhang, Qiong
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Fang, Weihai
    Beijing Normal University.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Intrinsic property of flavin mononucleotide controls its optical spectra in three redox states2011In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 12, no 16, p. 2899-2902Article in journal (Refereed)
  • 25. Akabori, M.
    et al.
    Hidaka, S.
    Iwase, H.
    Yamada, S.
    Ekenberg, Ulf
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Realization of In0.75Ga0.25As two-dimensional electron gas bilayer system for spintronics devices based on Rashba spin-orbit interaction2012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 112, no 11, p. 113711-Article in journal (Refereed)
    Abstract [en]

    Narrow gap InGaAs two-dimensional electron gas (2DEG) bilayer samples are fabricated and confirmed to have good electronic qualities as well as strong Rashba-type spin-orbit interactions (SOIs). The 2DEG systems are realized by molecular beam epitaxy in the form of wide quantum wells (QWs) with thicknesses tQW∼40-120nm modulation doped in both the upper and lower InAlAs barriers. From the Hall measurements, the overall mobility values of μe ∼15 m2/V s are found for the total sheet electron density of ns ∼8 × 1011/cm2, although the ns is distributed asymmetrically as about 1:3 in the upper and lower 2DEGs, respectively. Careful low temperature magneto-resistance analysis gives large SO coupling constants of α ∼20 × 10 -12eV m as well as expected electron effective masses of m*/m0 ∼0.033-0.042 for each bilayer 2DEG spin sub-band. Moreover, the enhancement of α with decrease of tQW is found. The corresponding self-consistent calculation, which suggests the interaction between the bilayer 2DEGs, is carried out and the origin of α enhancement is discussed.

  • 26.
    Akan, Rabia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Metal-assisted chemical etching for nanofabrication of hard X-ray zone plates2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Hard X-ray scanning microscopes, or nanoprobes, make it possible to image samples and probe their chemical, elemental and structural properties at nanoscale resolution. This is enabled by the use of nanofocusing optics. Commonly used optics in nanoprobes for high resolution X-ray experiments are zone plates. Zone plates are circular diffraction optics with radially decreasing grating periods. Their performance depends on their geometrical properties and material. The width of the outermost zone, which today is in the order of a few tens of nanometers, defines the zone plate resolution, while the zone thickness and the material define the X-ray focusing efficiency. For hard X-ray zone plates, the required zone thickness is several micrometers. Therefore, high-aspect ratio nanostructures are a prerequisite for high-resolution, high-efficiency zone plates. The very small structures together with the high-aspect ratios make zone plates one of the most challenging devices to fabricate. A wet-chemical nanofabrication process that has proved its capability of providing silicon nanostructures with ultra-high aspect ratios is metal-assisted chemical etching (MACE). MACE is an electroless, autocatalytic pattern transfer method that uses an etching solution to selectively etch a predefined noble metal pattern into silicon. In this thesis, MACE is optimized specifically for zone plate nanostructures and used in the development of a new zone plate device nanofabrication process. The MACE optimization for silicon zone plate nanostructures involved a systematic investigation of a wide parameter space. The preferable etching solution composition, process temperature, zone plate catalyst design and silicon type were identified. Parameter dependencies were characterized with respect to etching depth and verticality, mechanical stability of zones and silicon surface roughness. Zone plate molds with aspect ratios of 30:1 at 30 nm zone widths were nanofabricated using the optimized MACE process. For use with hard X-rays, the silicon molds were metallized with palladium using electroless deposition (ELD). The first order diffraction efficiency of such a palladium/silicon zone plate was characterized as 1.9 %. Both MACE for the zone plate pattern transfer and ELD for the silicon mold metalization are conceptually simple, relatively low-cost and accessible methods, which opens up for further developments of zone plate device nanofabrication processes.

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  • 27.
    Akan, Rabia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Parfeniukas, Karolis
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Toprak, Muhammet
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Investigation of Metal-Assisted Chemical Etching for Fabrication of Silicon-Based X-Ray Zone Plates2018In: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115Article in journal (Refereed)
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  • 28.
    Akan, Rabia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Optimization of metal-assisted chemical etching for deep silicon nanostructuresManuscript (preprint) (Other academic)
  • 29.
    Akan, Rabia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Optimization of Metal-Assisted Chemical Etching for Deep Silicon Nanostructures2021In: Nanomaterials, E-ISSN 2079-4991, Vol. 11, no 11, article id 2806Article in journal (Refereed)
    Abstract [en]

    High-aspect ratio silicon (Si) nanostructures are important for many applications. Metal-assisted chemical etching (MACE) is a wet-chemical method used for the fabrication of nanostructured Si. Two main challenges exist with etching Si structures in the nanometer range with MACE: keeping mechanical stability at high aspect ratios and maintaining a vertical etching profile. In this work, we investigated the etching behavior of two zone plate catalyst designs in a systematic manner at four different MACE conditions as a function of mechanical stability and etching verticality. The zone plate catalyst designs served as models for Si nanostructures over a wide range of feature sizes ranging from 850 nm to 30 nm at 1:1 line-to-space ratio. The first design was a grid-like, interconnected catalyst (brick wall) and the second design was a hybrid catalyst that was partly isolated, partly interconnected (fishbone). Results showed that the brick wall design was mechanically stable up to an aspect ratio of 30:1 with vertical Si structures at most investigated conditions. The fishbone design showed higher mechanical stability thanks to the Si backbone in the design, but on the other hand required careful control of the reaction kinetics for etching verticality. The influence of MACE reaction kinetics was identified by lowering the oxidant concentration, lowering the processing temperature and by isopropanol addition. We report an optimized MACE condition to achieve an aspect ratio of at least 100:1 at room temperature processing by incorporating isopropanol in the etching solution.

  • 30.
    Akhmedov, Evgeny
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Particle Physics.
    Neutrino oscillations: Theory and phenomenology2011In: Nuclear Physics B - Proceedings Supplements, ISSN 0920-5632, Vol. 221, p. 19-25Article in journal (Refereed)
    Abstract [en]

    A brief overview of selected topics in the theory and phenomenology of neutrino oscillations is given. These include: oscillations in vacuum and in matter; phenomenology of 3-flavour neutrino oscillations; CP and T violation in neutrino oscillations in vacuum and in matter; matter effects on ν μ↔ν τ oscillations; parametric resonance in neutrino oscillations inside the earth; oscillations below and above the MSW resonance; unsettled issues in the theory of neutrino oscillations.

  • 31. Aktas, Ozan
    et al.
    Ren, H.
    Runge, A. F. J.
    Peacock, A. C.
    Hawkins, T.
    Ballato, J.
    Gibson, Ursula J.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Interfacing telecom fibers and silicon core fibers with nano-spikes for in-fiber silicon devices2018In: Optics InfoBase Conference Papers, Optics Info Base, Optical Society of America, 2018, article id u12d3i3mConference paper (Refereed)
    Abstract [en]

    We report fabrication of tapered silicon core fibers with nano-spikes enabling efficient optical coupling into the core, as well as their seamless integration with single mode fibers. A proof-of-concept integrated in-fiber silicon device is demonstrated. 

  • 32.
    Al-attar, Nebras
    et al.
    School of biosystems and food Engineering, University of Technology, Baghdad, 10066, Iraq; Laser and Optoelectronics Engineering Department, University of Technology, Baghdad, 10066, Iraq.
    Al-Shammari, Rusul M.
    School of Physics, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland; Conway Institute of Biomolecular and Biomedical Research, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Rodriguez, Brian J.
    School of Physics, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland; Conway Institute of Biomolecular and Biomedical Research, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland.
    Rice, James H.
    School of Physics, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland.
    Wide-field surface-enhanced Raman scattering from ferroelectrically defined Au nanoparticle microarrays for optical sensing2018In: Proceedings CLEO: Applications and Technology 2018, Optica Publishing Group , 2018Conference paper (Refereed)
    Abstract [en]

    The acquisition-time in optical sensors using SERS is vital value. Wide-field SERS is used to perform high-density of hot-spots of GNPs photodeposition on a periodically-protonexchanged- LiNbO3 which, leads to increase the sensitivity at ultralow probe concentrations.

  • 33.
    Albernaz, Daniel L.
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Do-Quang, Minh
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Hermanson, J. C.
    Amberg, Gustav
    KTH, School of Engineering Sciences (SCI), Mechanics, Physicochemical Fluid Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Thermodynamics of a real fluid near the critical point in numerical simulations of isotropic turbulence2016In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 28, no 12, article id 125105Article in journal (Refereed)
    Abstract [en]

    We investigate the behavior of a fluid near the critical point by using numerical simulations of weakly compressible three-dimensional isotropic turbulence. Much has been done for a turbulent flow with an ideal gas. The primary focus of this work is to analyze fluctuations of thermodynamic variables (pressure, density, and temperature) when a non-ideal Equation Of State (EOS) is considered. In order to do so, a hybrid lattice Boltzmann scheme is applied to solve the momentum and energy equations. Previously unreported phenomena are revealed as the temperature approaches the critical point. Fluctuations in pressure, density, and temperature increase, followed by changes in their respective probability density functions. Due to the non-linearity of the EOS, it is seen that variances of density and temperature and their respective covariance are equally important close to the critical point. Unlike the ideal EOS case, significant differences in the thermodynamic properties are also observed when the Reynolds number is increased. We also address issues related to the spectral behavior and scaling of density, pressure, temperature, and kinetic energy.

  • 34. Alcusa-Saez, E. P.
    et al.
    Diez, A.
    Rivera-Perez, E.
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Norin, Lars
    Andres, M. V.
    All-fiber acousto-optic tunable filter in polyimide coated optical fibers2017In: 2017 19th International Conference on Transparent Optical Networks (ICTON), IEEE Computer Society, 2017, article id 8025093Conference paper (Refereed)
    Abstract [en]

    We present the experimental demonstration of in-fiber acousto-optic coupling in a polyimide-coated optical fiber. Although the presence of the polyimide coating increases is significantly the attenuation of the acoustic wave, we show that acousto-optic interaction can still be produced with reasonable efficiency. The effect of the polyimide coating on the acousto-optic interaction process is analyzed in detailed. Theoretical and experimental results are in good agreement. To our knowledge, this is the first experimental demonstration of acousto-optic coupling in optical fibers with robust protective coating.

  • 35. Aldongarov, Anuar
    et al.
    Irgibaeva, Irina
    Hermansson, Kersti
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Theoretical study on passivation of small CdS clusters2014In: Molecular Physics, ISSN 0026-8976, E-ISSN 1362-3028, Vol. 112, no 5-6, p. 674-682Article in journal (Refereed)
    Abstract [en]

    We use density functional theory quantum chemical calculations to model optical properties of small cadmium sulphide clusters in order to explore the formation of trap states and the possibility to achieve surface passivation. The addition of capping oxygen ions on the surface of the CdS quantum dots is found to passivate the single-bonded Cd atoms. Added Cu ions resulted in the formation of deep trap states for certain locations of the copper impurity, while removal of single-bonded Cd atoms by adding S or SH groups leads to a band gap increase.

  • 36.
    Alizad Banaei, Arash
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Rahmani, Mona
    Univ British Columbia, Dept Math, Vancouver, BC V6T 1Z2, Canada..
    Martinez, D. Mark
    Univ British Columbia, Dept Chem & Biol Engn, Vancouver, BC V6T 1Z3, Canada..
    Brandt, Luca
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Inertial settling of flexible fiber suspensions2020In: Physical Review Fluids, E-ISSN 2469-990X, Vol. 5, no 2, article id 024301Article in journal (Refereed)
    Abstract [en]

    We study the inertial settling of suspensions of flexible and rigid fibers using an immersed boundary method. The fibers considered are inextensible and slender, with an aspect ratio of 20. For a single Galileo number of Ga = 160, we examine a range of dimensionless bending rigidities 0.1 < gamma < 20 and fiber concentrations 0.5 < nL(3) < 25, with n being the fiber number density and L the fiber length, that spans dilute and semidilute regimes. The settling fibers form streamers, regions where the fibers are packed and settle faster than the average settling velocity of the suspension, for nL(3) > 10. In the low-concentration regions outside the streamers, the fibers either go upward or have low settling velocities. Flexible fibers exhibit higher packing inside the streamers and smaller streamers compared to the streamers formed by the rigid fibers. Due to this higher packing, the flexible fibers settle faster compared to the rigid fibers. The formation of the streamers counterbalances the hindering of the settling velocity at higher concentrations. At higher nL(3), however, the maximum local concentration of fibers relative to a uniform distribution diminishes for both flexible and rigid fibers as the mobility of the fibers becomes limited due to the presence of other fibers in their vicinity. Due to this limited mobility, the deformation of the fibers and their settling orientation become insensitive to nL(3) for nL(3) > 7. In both the dilute and semidilute regimes, flexible fibers are more aligned with the direction perpendicular to gravity compared to rigid fibers.

  • 37.
    Almlöf, Jonas
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    Björk, Gunnar
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
    A short and efficient quantum-erasure code for polarization-coded photonic qubits2009In: CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009, p. 5191786-Conference paper (Refereed)
  • 38.
    Al-Soubaihi, Rola
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Saoud, K. M.
    Virginia Commonwealth University in Qatar, Libral Arts and Sciences Program, P.O. Box 8095, Doha, Qatar.
    Fei, Ye
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Zar Myint, M. T.
    Department of Physics, College of Science, Sultan Qaboos University, P.O. Box 36, Muscat, PC 123, Oman.
    Saeed, S.
    Department of Chemistry, Paksitan Institute of Engineering and Applied Sciences (PIEAS), PO Nilore, Islamabad, 45650, Pakistan.
    Dutta, Joydeep
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Synthesis of hierarchically porous silica aerogel supported Palladium catalyst for low-temperature CO oxidation under ignition/extinction conditions2020In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 292, article id 109758Article in journal (Refereed)
    Abstract [en]

    Synthesis of well-dispersed palladium nanoparticles within silica aerogel pores with controlled size was carried out using sol-gel synthesis under supercritical ethanol drying. The high concentration of silanol groups on silica (SiO2) surface facilitated a superior palladium (Pd) loading up to 10 wt %. The synthesized Pd/SiO2 nanocomposite aerogels were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopic methods. The silica aerogel supported catalysts were found to have a wide pore size distribution. TEM investigations confirmed that Pd nanocrystals were located within the SiO2 microspores and mesopores. The catalyst was evaluated for carbon monoxide (CO) oxidation reaction under ignition/extinction conditions. The synthesized catalyst demonstrated a high catalytic activity at low operating temperatures (&lt;200 °C) compared to unsupported Pd nanoparticles or bare SiO2 aerogels. This enhancement in CO oxidation activity with Pd/SiO2 aerogel catalysts are attributed to the small Pd particles, Pd interaction with the surface of the underlying SiO2 and the better dispersion of Pd particles within the SiO2 pores. Porosity played a more important role during the extinction cycle as a result of the slow dissipation of the heat leading to hysteresis. We demonstrate the influence of porosity of catalyst supports on the size, dispersion, and catalytic activity of Pd nanoparticles.

  • 39. Amarouch, Mohamed-Yassine
    et al.
    Kurt, Han
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Delemotte, Lucie
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Abriel, Hugues
    Biophysical Characterization of Epigallocatechin-3-Gallate Effect on the Cardiac Sodium Channel Na(v)1.52020In: Molecules, ISSN 1431-5157, E-ISSN 1420-3049, Vol. 25, no 4, article id 902Article in journal (Refereed)
    Abstract [en]

    Epigallocatechin-3-Gallate (EGCG) has been extensively studied for its protective effect against cardiovascular disorders. This effect has been attributed to its action on multiple molecular pathways and transmembrane proteins, including the cardiac Na(v)1.5 channels, which are inhibited in a dose-dependent manner. However, the molecular mechanism underlying this effect remains to be unveiled. To this aim, we have characterized the EGCG effect on Na(v)1.5 using electrophysiology and molecular dynamics (MD) simulations. EGCG superfusion induced a dose-dependent inhibition of Na(v)1.5 expressed in tsA201 cells, negatively shifted the steady-state inactivation curve, slowed the inactivation kinetics, and delayed the recovery from fast inactivation. However, EGCG had no effect on the voltage-dependence of activation and showed little use-dependent block on Na(v)1.5. Finally, MD simulations suggested that EGCG does not preferentially stay in the center of the bilayer, but that it spontaneously relocates to the membrane headgroup region. Moreover, no sign of spontaneous crossing from one leaflet to the other was observed, indicating a relatively large free energy barrier associated with EGCG transport across the membrane. These results indicate that EGCG may exert its biophysical effect via access to its binding site through the cell membrane or via a bilayer-mediated mechanism.

  • 40.
    Anand, Srinivasan
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Shahid, Naeem
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Naureen, Shagufta
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Li, Mingyu
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA. Zhejiang University, Hangzhou, China.
    Swillo, Marcin
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    InP-based photonic crystal waveguide filters2010In: 2010 Asia Communications and Photonics Conference and Exhibition, ACP 2010, 2010, p. 104-105Conference paper (Refereed)
  • 41. Anderson, Louise
    et al.
    Zarembo, Konstantin
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Stockholm University, Stockholm, Sweden; Uppsala University, Uppsala, Sweden; ITEPMoscow, Russian Federation .
    Quantum phase transitions in mass-deformed ABJM matrix model2014In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 9, p. 021-Article in journal (Refereed)
    Abstract [en]

    When mass-deformed ABJM theory is considered on S-3, the partition function of the theory localises, and is given by a matrix model. At large N, we solve this model in the decompactification limit, where the radius of the three-sphere is taken to infinity. In this limit, the theory exhibits a rich phase structure with an infinite number of third-order quantum phase transitions, accumulating at strong coupling.

  • 42. Andersson, John
    et al.
    Shahgholian, Henrik
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    Weiss, Georg S.
    Uniform Regularity Close to Cross Singularities in an Unstable Free Boundary Problem2010In: Communications in Mathematical Physics, ISSN 0010-3616, E-ISSN 1432-0916, Vol. 296, no 1, p. 251-270Article in journal (Refereed)
    Abstract [en]

    We introduce a new method for the analysis of singularities in the unstable problem Delta u = chi{u> 0}, which arises in solid combustion as well as in the composite membrane problem. Our study is confined to points of "supercharacteristic" growth of the solution, i.e. points at which the solution grows faster than the characteristic/invariant scaling of the equation would suggest. At such points the classical theory is doomed to fail, due to incompatibility of the invariant scaling of the equation and the scaling of the solution. In the case of two dimensions our result shows that in a neighborhood of the set at which the second derivatives of u are unbounded, the level set {u = 0} consists of two C-1-curves meeting at right angles. It is important that our result is not confined to the minimal solution of the equation but holds for all solutions.

  • 43.
    Andresen, Juan Carlos
    et al.
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory. Theoretische Physik, ETH Zurich, Zurich, Switzerland.
    Pramudya, Yohanes
    Katzgraber, Helmut G.
    Thomas, Creighton K.
    Zimanyi, Gergely T.
    Dobrosavljevic, V.
    Charge avalanches and depinning in the Coulomb glass: The role of long-range interactions2016In: Physical Review B, ISSN 2469-9950, Vol. 93, no 9, article id 094429Article in journal (Refereed)
    Abstract [en]

    We explore the stability of far-from-equilibrium metastable states of a three-dimensional Coulomb glass at zero temperature by studying charge avalanches triggered by a slowly varying external electric field. Surprisingly, we identify a sharply defined dynamical ("depinning") phase transition from stationary to nonstationary charge displacement at a critical value of the external electric field. Using particle-conserving dynamics, scale-free system-spanning avalanches are observed only at the critical field. We show that the qualitative features of this depinning transition are completely different for an equivalent short-range model, highlighting the key importance of long-range interactions for nonequilibrium dynamics of Coulomb glasses.

  • 44. Andreyev, A. N.
    et al.
    Huyse, M.
    Van Duppen, P.
    Qi, Chong
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Liotta, Roberto J.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Antalic, S.
    Ackermann, D.
    Franchoo, S.
    Heßberger, F. P.
    Hofmann, S.
    Kojouharov, I.
    Kindler, B.
    Kuusiniemi, P.
    Lesher, S. R.
    Lommel, B.
    Mann, R.
    Nishio, K.
    Page, R. D.
    Streicher, B.
    Šáro, Š.
    Sulignano, B.
    Wiseman, D.
    Wyss, Ramon A .
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Signatures of the Z=82 shell closure in alpha-decay process2013In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 110, no 24, article id 242502Article in journal (Refereed)
    Abstract [en]

    In recent experiments at the velocity filter Separator for Heavy Ion reaction Products (SHIP) (GSI, Darmstadt), an extended and improved set of α-decay data for more than 20 of the most neutron-deficient isotopes in the region from lead to thorium was obtained. The combined analysis of this newly available α-decay data, of which the Po186 decay is reported here, allowed us for the first time to clearly show that crossing the Z=82 shell to higher proton numbers strongly accelerates the α decay. From the experimental data, the α-particle formation probabilities are deduced following the Universal Decay Law approach. The formation probabilities are discussed in the framework of the pairing force acting among the protons and the neutrons forming the α particle. A striking resemblance between the phenomenological pairing gap deduced from experimental binding energies and the formation probabilities is noted. These findings support the conjecture that both the N=126 and Z=82 shell closures strongly influence the α-formation probability.

  • 45. Andreyev, A. N.
    et al.
    Huyse, M.
    Van Duppen, P.
    Weissman, L.
    Ackermann, D.
    Gerl, J.
    Hessberger, F. P.
    Hofmann, S.
    Kleinbohl, A.
    Munzenberg, G.
    Reschitko, S.
    Schlegel, C.
    Schaffner, H.
    Cagarda, P.
    Matos, M.
    Saro, S.
    Keenan, A.
    Moore, C. J.
    O'Leary, C. D.
    Page, R. D.
    Taylor, M. J.
    Kettunen, H.
    Leino, M.
    Lavrentiev, A.
    Wyss, Ramon
    KTH, Superseded Departments (pre-2005), Physics. Department of Technology, Kalmar University, Box 905, 391 29 Kalmar, Sweden.
    Heyde, K.
    The discovery of a prolate-oblate-spherical shape triple of spin 0(+) states in the atomic nucleus Pb-1862001In: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 682, p. 482C-486CArticle in journal (Refereed)
    Abstract [en]

    Two excited J(pi)=0(+) states in Pb-186 populated in the a-decay of Po-190 have been identified through alpha -particle/conversion electron coincidences in an experiment at the velocity filter SHIP. The parent Po-190 nuclei have been produced in the Nd-142(Cr-52,4n)Po-190 complete fusion reaction, alpha -particle energies and branching ratios have been measured and hindrance factors were deduced. The observed states have been interpreted as the band heads of the known prolate and (yet unobserved) oblate rotational bands in Pb-186.

  • 46. Andrievsky, Alexander
    et al.
    Brandenburg, Axel
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Department of Astronomy, Stockholm University, AlbaNova University Center, Stockholm, Sweden.
    Noullez, Alain
    Zheligovsky, Vladislav
    Negative magnetic eddy diffusivities from the test-field method and multiscale stability theory2015In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 811, no 2, article id 135Article in journal (Refereed)
    Abstract [en]

    The generation of a large-scale magnetic field in the kinematic regime in the absence of an alpha-effect is investigated by following two different approaches: the test-field method and the multiscale stability theory relying on the homogenization technique. Our computations of the magnetic eddy diffusivity tensor of the parity-invariant flow IV of G. O. Roberts and the modified Taylor-Green flow confirm the findings of previous studies. and also explain some of their apparent contradictions. The two flows have large symmetry groups; this is used to considerably simplify the eddy diffusivity tensor. Finally, a new analytic result is presented: upon expressing the eddy diffusivity tensor in terms of solutions to auxiliary problems for the adjoint operator, we derive relations between the magnetic eddy diffusivity tensors that arise for mutually reverse small-scale flows v(x) and - v(x).

  • 47.
    Angelopoulou, Michailia
    et al.
    NCSR Demokritos, Inst Nucl & Radiol Sci & Technol Energy & Safety, Aghia Paraskevi 15341, Greece..
    Makarona, Eleni
    NCSR Demokritos, Inst Nanosci & Nanotechnol, Aghia Paraskevi 15341, Greece..
    Salapatas, Alexandros
    NCSR Demokritos, Inst Nanosci & Nanotechnol, Aghia Paraskevi 15341, Greece..
    Misiakos, Konstantinos
    NCSR Demokritos, Inst Nanosci & Nanotechnol, Aghia Paraskevi 15341, Greece..
    Synolaki, Evgenia
    Biomed Res Fdn Acad Athens, Ctr Clin Expt Surg & Translat Res, Athens 11527, Greece..
    Ioannidis, Anastasios
    Univ Peloponnese, Fac Hlth Sci, Dept Nursing, Tripoli 22100, Greece..
    Chatzipanagiotou, Stylianos
    Ritvos, Mikael A.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH). Natl & Kapodistrian Univ Athens, Aeginit Hosp, Med Sch, Dept Med Biopathol & Clin Microbiol, Athens 11528, Greece.;Univ Helsinki, Fac Med, Dept Physiol, Helsinki 00014, Finland.;Nord SARS Response AB, S-19455 Stockholm, Sweden..
    Pasternack, Arja
    Natl & Kapodistrian Univ Athens, Aeginit Hosp, Med Sch, Dept Med Biopathol & Clin Microbiol, Athens 11528, Greece..
    Ritvos, Olli
    Natl & Kapodistrian Univ Athens, Aeginit Hosp, Med Sch, Dept Med Biopathol & Clin Microbiol, Athens 11528, Greece..
    Petrou, Panagiota S.
    NCSR Demokritos, Inst Nucl & Radiol Sci & Technol Energy & Safety, Aghia Paraskevi 15341, Greece.;NCSR Demokritos, INRASTES, Res Immunoassays Immunosensors Lab, Aghia Paraskevi 15341, Greece..
    Kakabakos, Sotirios E.
    Directly immersible silicon photonic probes: Application to rapid SARS-CoV-2 serological testing br2022In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 215, article id 114570Article in journal (Refereed)
    Abstract [en]

    Silicon photonic probes based on broad-band Mach-Zehnder interferometry are explored for the first time as directly immersible immunosensors alleviating the need for microfluidics and pumps. Each probe includes two U- shaped waveguides allowing light in- and out-coupling from the same chip side through a bifurcated fiber and a mechanical coupler. At the opposite chip side, two Mach-Zehnder interferometers (MZI) are located enabling real-time monitoring of binding reactions by immersion of this chip side into a sample. The sensing arm windows of the two MZIs have different length resulting in two distinct peaks in the Fourier domain, the phase shift of which can be monitored independently through Fast Fourier Transform of the output spectrum. The photonic probes analytical potential was demonstrated through detection of antibodies against SARS-CoV-2 in human serum samples. For this, one MZI was functionalized with the Receptor Binding Domain (RBD) of SARS-CoV-2 Spike 1 protein, and the other with bovine serum albumin to serve as reference. The biofunctionalized probes were immersed for 10 min in human serum sample and then for 5 min in goat anti-human IgG Fc specific antibody solution. Using a humanized rat antibody against SARS-CoV-2 RBD, a detection limit of 20 ng/mL was determined. Analysis of human serum samples indicated that the proposed sensor discriminated completely non- infected/non-vaccinated from vaccinated individuals, and the antibodies levels determined correlated well with those determined in the same samples by ELISA. These results demonstrated the potential of the proposed sensor to serve as an efficient tool for expeditious point-of-care testing

  • 48.
    Anghel, Ionut Gheorghe
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Anglart, Henryk
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Post-dryout heat transfer to high-pressure water flowing upward in vertical channels with various flow obstacles2012In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 55, no 25-26, p. 8020-8031Article in journal (Refereed)
    Abstract [en]

    Post-dryout heat transfer to high pressure water was investigated experimentally in vertical tubes and annuli containing various flow obstacles. The operational conditions during the experiments were as follows: mass flux from 500 to 1750 kg/m(2) s. pressure from 5 to 9 MPa, inlet subcooling from 10 to 40K and heat flux up to 1.5 MW/m(2). Five different test sections were used in experiments: three annular test sections with inner diameter 12.7 mm and outer diameter 24.3 mm, containing cylindrical and grid flow obstacles in the upper part, and two tubular test sections with inner diameter 24.3 mm with and without pin flow obstacles. The heated length in all test sections was 3650 mm. The wall temperature was measured with 88 thermocouples located along the inner rod and the outer tube surfaces. Due to the presence of flow obstacles, only developing post-dryout heat transfer was observed. Selected post-dryout heat transfer correlations were compared to the experimental data. It has been concluded that all tested correlations predict significantly higher wall temperatures than those obtained in the present experiment. A simple correction function to the Saha model has been suggested which significantly improves the agreement between the correlation and the present data.

  • 49.
    Anglart, Henryk
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Numerical analysis of the onset of heat transfer deterioration to supercritical water2010In: International Congress on Advances in Nuclear Power Plants 2010, ICAPP 2010: Volume 3, 2010, p. 1689-1695Conference paper (Refereed)
    Abstract [en]

    In this paper the mechanism of the onset of heat transfer deterioration to supercritical water is elucidated with detailed numerical predictions of flow and heat transfer in the boundary layer. It is shown that for low mass flow rates the buoyancy effects are dominant and the deterioration of heat transfer is caused by the turbulence damping in the vicinity of the heated wall. For high mass flow rates the mechanism of deterioration changes and the triggering factor is the decrease of the thermal conductivity of fluid in the viscous sub-layer. A numerical prediction of this phenomenon requires application of a low Reynolds number turbulence model with y+ less than 1.

  • 50.
    Anglart, Henryk
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Thermal safety margins in nuclear reactors2024Book (Other academic)
    Abstract [en]

    This book presents an overview of state-of-the-art approaches to determine thermal safety margins in nuclear reactors. It presents both the deterministic aspects of thermal safety margins of nuclear reactors and a comprehensive treatment of aleatory and epistemic uncertainties to facilitate the understanding of these two difficult topics at various academic levels, from undergraduates to researchers in nuclear engineering. It first sets out the theoretical background before exploring how to determine thermal safety margins in nuclear reactors, through examples, problems and advanced state-of-the-art approaches. This will help undergraduate students better understand the most fundamental aspects of nuclear reactor safety. For researchers and practitioners, this book provides a comprehensive overview of the most recent achievements in the field, offering an excellent starting point to develop new methods for the assessment of the thermal safety margins. This book is written to bridge the gap between deterministic methods and appropriate treatment of uncertainties to assess safety margins in nuclear reactors, presenting these approaches as complementary to each other. Even though these two approaches are frequently used in parallel in real-world applications, there has been a lack of a consistent teaching approach in this area. This book is suitable for readers with a background in calculus, thermodynamics, fluid mechanics, and heat transfer. It is assumed that readers have previous exposure to such concepts as laws of thermodynamics, enthalpy, entropy, and conservation equations used in fluid mechanics and heat transfer. Key Features: • Covers the theory, principles, and assessment methods of thermal safety margins in nuclear reactors whilst presenting state-of-the-art technology in the field • Combines the deterministic thermal safety considerations with a comprehensive treatment of uncertainties, offering a framework that is applicable to all current and future commercial nuclear reactor types • Provides numerous examples and problems to be solved.

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