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  • 151.
    Björk, Jonas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk kemi. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Linköping University.
    Thermodynamics of an Electrocyclic Ring-Closure Reaction on Au(111)2016Ingår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, nr 38, s. 21716-21721Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have computationally studied the effects of temperature on the reaction pathway of an electrocyclic ring-closure reaction on the Au(111) surface, particularly focusing on thermodynamic aspects of the reaction. The electrocyclic ring closure is accompanied by a series of dehydrogenation steps, and while it is found that temperature, in terms of vibrational entropy and enthalpy, has a reducing effect on most energy barriers, it does not alter the qualitative appreciation of the reaction kinetics. However, it is found that the way the abstracted hydrogen atoms are treated is crucial for the thermodynamics of the reaction. The overall reaction is highly endothermic but becomes thermodynamically favorable due to the entropy gain of the hydrogen byproducts, which desorb associatively from the surface as H2. The study provides new outlooks for the theoretical treatment of reactions related to on-surface synthesis, anticipated to be instructive for future studies.

  • 152.
    Bleskov, I D
    et al.
    National University of Science and Technology MISiS, Moscow.
    Isaev, Eyvas
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Vekilov, Yu Kh
    National University of Science and Technology MISiS, Moscow.
    Electronic structure and ground state parameters of Ru1-x Me (x) Al refractory alloys2010Ingår i: PHYSICS OF THE SOLID STATE, ISSN 1063-7834, Vol. 52, nr 9, s. 1803-1809Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electronic structure and ground state parameters of B2 RuAl-based refractory alloys have been investigated in the framework of the density functional theory using the exact muffin-tin orbital method in combination with the coherent potential approximation. It has been demonstrated that the number of states at the Fermi level for the Ru1 - x Me (x) Al alloys as a function of the alloying metal content has a minimum, which indicates a change in the Fermi surface topology and the presence of specific features in the behavior of elastic constants. It has been concluded that the electronic structure of the alloys can be described in terms of the rigid band model. The nonlinear variations of the lattice parameters of the alloys has been explained.

  • 153.
    Bleskov, I D
    et al.
    Moscow State Institute Steel & Alloys.
    Smirnova, E A
    Moscow State Institute Steel & Alloys.
    Vekilov, Yu Kh
    Moscow State Institute Steel & Alloys.
    Korzhavyi, P A
    Royal Institute Technology.
    Johansson, B
    Royal Institute Technology.
    Katsnelson, M
    Radboud University Nijmegen.
    Vitos, L
    Royal Institute Technology.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Isaev, Eyvas
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Ab initio calculations of elastic properties of Ru1-xNixAl superalloys2009Ingår i: APPLIED PHYSICS LETTERS, ISSN 0003-6951, Vol. 94, nr 16, s. 161901-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ab initio total energy calculations based on the exact muffin-tin orbitals method, combined with the coherent potential approximation, have been used to study the thermodynamical and elastic properties of substitutional refractory Ru1-xNixAl alloys. We have found that the elastic constants C- and C-11 exhibit pronounced peculiarities near the concentration of about 40 at. % Ni, which we ascribe to electronic topological transitions. Our suggestion is supported by the Fermi surface calculations in the whole concentration range. Results of our calculations show that one can design Ru-Ni-Al alloys substituting Ru by Ni (up to 40 at. %) with almost invariable elastic constants and reduced density.

  • 154.
    Bleskov, Ivan
    et al.
    Natl University Science and Technology MISiS.
    Isaev, Eyvas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Vekilov, Yuri
    Natl University Science and Technology MISiS.
    Elastic constants of Ru100-xMexAl refractory alloys2011Ingår i: SOLID STATE COMMUNICATIONS, ISSN 0038-1098, Vol. 151, nr 3, s. 242-244Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Elastic constants of disordered refractory Ru100-xMexAl alloys are calculated from first principles using a density-functional-theory based exact muffin-tin orbitals method combined with a coherent potential approximation. As alloying elements we considered Me = Ni, Co, Ir and Fe. We have found that peculiarities in the concentration dependencies of elastic constants on alloying metals content depend on their position in the Periodic Table with respect to Ru. These peculiarities can be connected with the changes in the electronic structure which take place upon alloying.

  • 155.
    Bosak, A.
    et al.
    European Synchrotron Radiat Facil, France.
    Krisch, M.
    European Synchrotron Radiat Facil, France.
    Chumakov, A.
    European Synchrotron Radiat Facil, France.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. National University of Science and Technology MISIS, Russia.
    Dubrovinsky, L.
    University of Bayreuth, Germany.
    Possible artifacts in inferring seismic properties from X-ray data2016Ingår i: Physics of the Earth and Planetary Interiors, ISSN 0031-9201, E-ISSN 1872-7395, Vol. 260, s. 14-19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider the experimental and computational artifacts relevant for the extraction of aggregate elastic properties of polycrystalline materials with particular emphasis on the derivation of seismic velocities. We use the case of iron as an example, and show that the improper use of definitions and neglecting the crystalline anisotropy can result in unexpectedly large errors up to a few percent. (C) 2016 Elsevier B.V. All rights reserved.

  • 156.
    Bostrom, M.
    et al.
    University of Oslo, Norway; Norwegian University of Science and Technology, Norway.
    Thiyam, P.
    Royal Institute Technology, Sweden.
    Persson, C.
    University of Oslo, Norway; Royal Institute Technology, Sweden; University of Oslo, Norway.
    Parsons, D. F.
    Australian National University, Australia.
    Buhmann, S. Y.
    University of Freiburg, Germany; University of Freiburg, Germany.
    Brevik, I.
    Norwegian University of Science and Technology, Norway.
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Non-perturbative theory of dispersion interactions2015Ingår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 90, nr 3, s. 035405-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Some open questions exist with fluctuation-induced forces between extended dipoles. Conventional intuition derives from large-separation perturbative approximations to dispersion force theory. Here, we present a full non-perturbative theory. In addition, we discuss how one can take into account finite dipole size corrections. It is of fundamental value to investigate the limits of validity of the perturbative dispersion force theory.

  • 157.
    Bostrom, Mathias
    et al.
    Australian National University, Australia Norwegian University of Science and Technology, Norway .
    Brevik, Iver
    Norwegian University of Science and Technology, Norway .
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Dou, Maofeng
    Royal Institute Technology, Sweden .
    Persson, Clas
    Royal Institute Technology, Sweden University of Oslo, Norway .
    Ninham, Barry W.
    Australian National University, Australia .
    Enlarged molecules from excited atoms in nanochannels2012Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 86, nr 1, s. 014701-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The resonance interaction that takes place in planar nanochannels between pairs of excited-state atoms is explored. We consider interactions in channels of silica, zinc oxide, and gold. The nanosized channels induce a dramatically different interaction from that in free space. Illustrative calculations for two lithium and cesium atoms demonstrate that there is a short-range repulsion followed by long-range attraction. The binding energy is strongest near the surfaces. The size of the enlarged molecule is biggest at the center of the cavity and increases with channel width. Since the interaction is generic, we predict that enlarged molecules are formed in porous structures, and that the molecule size depends on the size of the nanochannels.

  • 158.
    Bostrom, Mathias
    et al.
    Royal Institute Technology, Sweden University of Oslo, Norway .
    Huang, Dan
    Royal Institute Technology, Sweden .
    Yang, Weihong
    Royal Institute Technology, Sweden .
    Persson, Clas
    Royal Institute Technology, Sweden University of Oslo, Norway University of Oslo, Norway .
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Lithium atom storage in nanoporous cellulose via surface-induced Li-2 breakage2013Ingår i: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 104, nr 6, s. 63003-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate a physical mechanism that enhances a splitting of diatomic Li-2 at cellulose surfaces. The origin of this splitting is a possible surface-induced diatomic-excited-state resonance repulsion. The atomic Li is then free to form either physical or chemical bonds with the cellulose surface and even diffuse into the cellulose layer structure. This allows for an enhanced storage capacity of atomic Li in nanoporous cellulose.

  • 159.
    Bostrom, Mathias
    et al.
    Norwegian University of Science and Technology, Norway Australian National University, Australia .
    Ninham, Barry W.
    Australian National University, Australia .
    Brevik, Iver
    Norwegian University of Science and Technology, Norway .
    Persson, Clas
    Royal Institute Technology, Sweden University of Oslo, Norway .
    Parsons, Drew F.
    Australian National University, Australia .
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ultrathin metallic coatings can induce quantum levitation between nanosurfaces2012Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, nr 25, s. 253104-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is an attractive Casimir-Lifshitz force between two silica surfaces in a liquid (bromobenze or toluene). We demonstrate that adding an ultrathin (5-50 angstrom) metallic nanocoating to one of the surfaces results in repulsive Casimir-Lifshitz forces above a critical separation. The onset of such quantum levitation comes at decreasing separations as the film thickness decreases. Remarkably, the effect of retardation can turn attraction into repulsion. From that we explain how an ultrathin metallic coating may prevent nanoelectromechanical systems from crashing together.

  • 160.
    Bostrom, Mathias
    et al.
    Norwegian University of Science and Technology, Norway .
    Ninham, Barry W.
    Australian National University, Australia .
    Brevik, Iver
    Norwegian University of Science and Technology, Norway .
    Persson, Clas
    Royal Institute Technology, Sweden .
    Parsons, Drew F.
    Australian National University, Australia .
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ultrathin metallic coatings can induce quantum levitation between nanosurfaces (vol 100, 253104, 2012)2013Övrigt (Refereegranskat)
    Abstract [en]

    n/a

  • 161.
    Boström, Mattias
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Lima, E R A
    Universidade Federal do Rio de Janeiro.
    Biscaia, E C
    Universidade Federal do Rio de Janeiro.
    Tavares, F W
    Universidade Federal do Rio de Janeiro.
    Nostro, P Lo
    Universidade Federal do Rio de Janeiro.
    Parsons, D F
    Australian National University .
    Deniz, V
    Australian National University .
    Ninham, B W
    Australian National University .
    Anion-Specific Partitioning in Two-Phase Finite Volume Systems: Possible Implications for Mechanisms of Ion Pumps.2009Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 113, nr 23, s. 8124-8127Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In two-phase finite volume systems of electroneutral phospholipids, the electrolyte concentration is different in the two phases. The partitioning is highly anion-specific, a phenomenon not accounted for by classical electrolyte theories. It is explained if ionic dispersion forces that lead to specific ion binding are taken into account. The mechanism provides a contribution to active ion pumps not previously considered.

  • 162.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Deniz, V.
    Research School of Physical Sciences and Engineering Australian National University Canberra.
    Ninham, B.W.
    Research School of Physical Sciences and Engineering Australian National University.
    Ion Specific Surface Forces between Membrane Surfaces2006Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 110, s. 9645-9649Artikel i tidskrift (Refereegranskat)
  • 163.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Deniz, Vivianne
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Franks, G.V.
    University of Melbourne.
    Ninham, B.W.
    Australian National University, Canberra.
    Extended DLVO theory: Electrostatic and non-electrostatic forces in oxide suspensions2006Ingår i: Advances in Colloid and Interface Science, ISSN 0001-8686, E-ISSN 1873-3727, Vol. 123-26Artikel i tidskrift (Refereegranskat)
  • 164.
    Boström, Mathias
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ellingsen, Simen A.
    Norwegian University of Science and Technology, Norway .
    Brevik, Iver
    Norwegian University of Science and Technology, Norway .
    Parsons, Drew F.
    Australian National University, Australia .
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Sign of the Casimir-Polder interaction between atoms and oil-water interfaces: Subtle dependence on dielectric properties2012Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 85, nr 6, s. 064501-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate that Casimir-Polder energies between noble gas atoms (dissolved in water) and oil-water interfaces are highly surface specific. Both repulsion (e.g., hexane) and attraction (e.g., glycerine and cyclodecane) is found with different oils. For several intermediate oils (e.g., hexadecane, decane, and cyclohexane) both attraction and repulsion can be found in the same system. Near these oil-water interfaces the interaction is repulsive in the nonretarded limit and turns attractive at larger distances as retardation becomes important. These highly surface specific interactions may have a role to play in biological systems where the surface may be more or less accessible to dissolved atoms.

  • 165.
    Boström, Mathias
    et al.
    Department of Energy and Process Engineering, Norwegian University of Science and Technology, Norway.
    Ellingsen, Simen Ådnöj
    Department of Energy and Process Engineering, Norwegian University of Science and Technology, Norway.
    Brevik, Iver
    Department of Energy and Process Engineering, Norwegian University of Science and Technology, Norway.
    Dou, M. F.
    Department of Materials Science and Engineering, Royal Institute of Technology, Sweden.
    Persson, Clas
    Department of Physics, University of Oslo, Norway.
    Sernelius, Bo E.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Casimir attractive-repulsive transition in MEMS2012Ingår i: European Physical Journal B: Condensed Matter Physics, ISSN 1434-6028, E-ISSN 1434-6036, Vol. 85, nr 11Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Unwanted stiction in micro- and nanomechanical (NEMS/MEMS) systems due to dispersion (van der Waals, or Casimir) forces is a significant hurdle in the fabrication of systems with moving parts on these length scales. Introducing a suitably dielectric liquid in the interspace between bodies has previously been demonstrated to render dispersion forces repulsive, or even to switch sign as a function of separation. Making use of recently available permittivity data calculated by us we show that such a remarkable non-monotonic Casimir force, changing from attractive to repulsive as separation increases, can in fact be observed in systems where constituent materials are in standard NEMS/MEMS use requiring no special or exotic materials. No such nonmonotonic behaviour has been measured to date. We calculate the force between a silica sphere and a flat surface of either zinc oxide or hafnia, two materials which are among the most prominent for practical microelectrical and microoptical devices. Our results explicate the need for highly accurate permittivity functions of the materials involved for frequencies from optical to far-infrared frequencies. A careful analysis of the Casimir interaction is presented, and we show how the change in the sign of the interaction can be understood as a result of multiple crossings of the dielectric functions of the three media involved in a given set-up.

  • 166.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Kunz, W.
    University of Regensburg.
    Ninham, B.W.
    Australian National University, Canberra.
    Hofmeister effects2005Ingår i: Water encyclopedia: Oceanography, Meteorology, Physics and chemistry, Water law and Water history, art and culture / [ed] Janet K. Lehr, Thomas B. Kingery, Hoboken, New Jersey: Wiley , 2005, s. 468-471Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Leading experts in water-related fields have come together to make Water Encyclopedia a one-stop, comprehensive reference about the world s most important natural resource. It covers designated topics in a clear concise and authoritative manner. The treatment is practical in orientation, keeping in mind the needs of the users. Theory is included only where required for an understanding of the topic.

  • 167.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Kunz, W.
    Inst. of Phys. and Theor. Chemistry, University of Regensburg, D-93040 Regensburg, Germany.
    Ninham, B.W.
    Inst. of Phys. and Theor. Chemistry, University of Regensburg, D-93040 Regensburg, Germany, Res. Sch. of Phys. Sci. and Eng., Australian National University, Canberra 0200, Australia.
    Hofmeister effects in surface tension of aqueous electrolyte solution2005Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, nr 6, s. 2619-2623Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The surface tension of electrolyte solutions shows marked specific ion effects. We here show an important role for both ionic solvation energies and ionic dispersion potentials in determining this ion specific surface tension of salt solutions. The ion self-free energy changes when an ion moves from bulk solution into the interfacial region, with its decreasing water density profile. We will show that the solvation energies of different ions correlate very well with the surface tension of salt solutions. Inclusion of this distance-dependent self-free energy contribution brings qualitative agreement with experiments and the right Hofmeister series. This is so not only for surface tension changes but also for measured surface potentials. The inclusion of ionic dispersion interaction potentials further improves the agreement with experiments. We discuss how further progress in the theory of the surface tension of salts can be achieved. © 2005 American Chemical Society.

  • 168.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Kunz, W.
    Institute of Physical and Theoretical Chemistry University of Regensburg.
    Ninham, B.W.
    Research School of Physical Sciences and Engineering Australian National University.
    Hofmeister Effects in Surface Tension of Aqueous Electrolyte Solution2005Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, s. 2619-2623Artikel i tidskrift (Refereegranskat)
  • 169.
    Boström, Mathias
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Lima, E. R. A.
    Universidade Federal do Rio de Janeiro.
    Biscaia Jr., E. C.
    Universidade Federal do Rio de Janeiro.
    Tavares, F. W.
    Universidade Federal do Rio de Janeiro.
    Kunz, W.
    University of Regensburg.
    Ion specific forces between charged self-assembled monolayersexplained by modified DLVO theory2009Ingår i: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 346, nr 1-3, s. 11-15Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We recently investigated specific ion effects near a single charged self-assembled monolayer (SAM) in asalt solution by exploiting a modified Poisson–Boltzmann equation that accounts for both water profileand ion-surface potential profiles inferred from molecular dynamics simulations. In the present contributionwe extend this work to consider two charged SAMs interacting across different salt solution. Ourresults demonstrate one important reason why the double layer force between charged colloidal surfacesin electrolytes could be highly ion specific.

  • 170.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Lima, E. R. A.
    Universidade Federal do Rio de Janeiro,.
    Tavares,, F. W.
    Universidade Federal do Rio de Janeiro,.
    Ninham, B. W.
    Australian National University, Canberra.
    The influence of ion binding and ion specific potentials on the double layer pressure between charged bilayers at low salt concentrations2008Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 128, s. 135104-1-135104-4Artikel i tidskrift (Refereegranskat)
  • 171.
    Boström, Mathias
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Lima, Eduardo R. A.
    Universidade Federal do Rio de Janeiro.
    Biscaia Jr., Evaristo C.
    Universidade Federal do Rio de Janeiro.
    Tavares, Frederico W.
    Universidade Federal do Rio de Janeiro.
    Kunz, Werner
    University of Regensburg.
    Modifying the Poisson-Boltzmann Approach to Model Specific Ion Effects2010Ingår i: Specific Ion Effects / [ed] Werner Kunz, Singapore: World Scientific Publishing Co. Pte. Ltd. , 2010, s. 293-309Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Specific ion effects are important in numerous fields of science and technology. They have been discussed for over 100 years, ever since the pioneering work done by Franz Hofmeister and his group in Prague. Over the last decades, hundreds of examples have been published and periodically explanations have been proposed. However, it is only recently that a profound understanding of the basic effects and their reasons could be achieved. Today, we are not far from a general explanation of specific ion effects. This book summarizes the main new ideas that have come up in the last ten years.

    In this book, the efforts of theoreticians are substantially supported by the experimental results stemming from new and exciting techniques. Both the new theoretical concepts and the experimental landmarks are collected and critically discussed by eminent scientists and well-known specialists in this field. Beyond the rigorous explanations, guidelines are given to non-specialists in order to help them understand the general rules governing specific ion effects in chemistry, biology, physics and engineering.

  • 172.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Lonetti, B.
    University of Florence.
    Fratini, E.
    University of Florence.
    Baglioni, P.
    University of Florence.
    Ninham, B.W.
    Australian National University.
    Why pH titration in protein solutions follows a Hofmeister series2006Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 110, nr 14, s. 7563-7566Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Measurements of pH in single-phase cytochrome c suspensions are reported. The pH, as determined by a glass electrode, has a fixed value. With the addition of salt, the supposedly fixed pH changes strongly. The pH depends on salt type and concentration and follows a Hofmeister series. A theoretical interpretation is given that provides insights into such Hofmeister effects. These occur generally in protein solutions. While classical electrostatic models provide partial understanding of such trends in protein solutions, they fail to explain the observed ion specificity. Such models neglect electrodynamic fluctuation (dispersion) forces acting between ions and proteins. We use a Poisson-Boltzmann cell model that takes these ionic dispersion potentials between ions and proteins into account. The observed ion specificity can then be accounted for. Proteins act as buffers that display similar salt-dependent pH trends not previously explained.

  • 173.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Ninham, B.W.
    Department of Applied Mathematics, Res. Sch. of Phys. Sci./Engineering, Australian National University, Canberra 0200, Australia.
    Atomic resonance interaction in dielectric media2004Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 69, nr 5 B, s. 054701-1Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The retarded resonance interaction in dielectric media between a ground state atom and an excited atom were investigated. The whole system was represented by a superposition of states:symmetric and antisymmetric with respect to interchange of atoms. While the antisymmetric state can be long lived, the asymmetric state is likely to decay into two ground state atoms. The retarded limit large deviations were demonstrated.

  • 174.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Ninham, B.W.
    Res. Sch. of Phys. Sci./Engineering, Australian National University, Canberra, 0200, Australia, Inst. of Phys./Theoretical Chemistry, University of Regensburg, D-93040 Regensburg, Germany.
    Contributions from dispersion and born self-free energies to the solvation energies of salt solutions2004Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 108, nr 33, s. 12593-12595Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    That the Born theory provides an accurate means of calculating solvation energies of ions in water has been demonstrated by Rashin and Honig (Rashin, A. A., Honig, B. J. Phys. Chem. 1985, 89, 5588). They could fit the experimental solvation energies of a number of salts nicely by a simple increase of 7% in the expected radii of all ions. However, as we demonstrate herein, there is an important previously ignored contribution due to the ionic dispersion self-free energy. The ionic parameters necessary to estimate the different contributions to solvation energy are the ionic radii, the ionic polarizabilities, and the ionization potentials. Whereas the polarizabilities and ionization potentials of a number of salts have recently been derived ab initio (in both vacuum and water), the appropriate choices of radii are less well-known. We pursue two different approaches to assign the ionic radii. In the first approach, we find that an increase of all expected radii by 23% gives reasonable agreement between theory and experiment (to within 6%). In the second approach, we increased the expected radii of six ions separately (10-30%) to obtain a best fit for the nine salts investigated. In this second approach, the deviations between theory and experiment were less than 0.1%. The essential point is that a proper theory must include contributions from both electrostatic (Born) and electrodynamic (dispersion) self-free energies.

  • 175.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Ninham, B.W.
    Res. Sch. of Phys. Sci. and Eng., Australian National University, Canberra, 0200, Australia, Inst. of Phys. and Theor. Chemistry, University of Regensburg, D-93040 Regensburg, Germany.
    Dispersion self-free energies and interaction free energies of finite-sized ions in salt solutions2004Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 20, nr 18, s. 7569-7574Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The role for many-body dipolar (dispersion) potentials in ion-solvent and ion-solvent-interface interactions is explored. Such many-body potentials, accessible in principle from measured dielectric data, are necessary in accounting for Hofmeister specific ion effects. Dispersion self-energy is the quantum electrodynamic analogue of the Born electrostatic self-energy of an ion. We here describe calculations of dispersion self-free energies of four different anions (OH-, Cl-, Br-, and I-) that take finite ion size into account. Three different examples of self-free energy calculations are presented. These are the self-free energy of transfer of an ion to bulk solution, which influences solubility, the dispersion potential acting between one ion and an air-water interface (important for surface tension calculations), and the dispersion potential acting between two ions (relevant to activity coefficient calculations). To illustrate the importance of dispersion self-free energies, we compare the Born and dispersion contributions to the free energy of ion transfer from water to air (oil). We have also calculated the change in interfacial tension with added salt for air (oil)-water interfaces. A new model is used that includes dispersion potentials acting on the ions near the interface, image potentials, and ions of finite size that are allowed to spill over the solution-air interface. It is shown that interfacial free energies require a knowledge of solvent profiles at the interface.

  • 176.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Ninham, B.W.
    Australian National University Canberra, and University of Regensburg.
    Dissolved gases2005Ingår i: Water encyklopedia: Oceanography, Meterology, Physics and Chemistry, Water law and Water history, art and culture / [ed] Janet K. Lehr, Thomas B. Kingery, Hoboken, New Jersey: Wiley , 2005, s. 450-452Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Leading experts in water-related fields have come together to make Water Encyclopedia a one-stop, comprehensive reference about the world s most important natural resource. It covers designated topics in a clear concise and authoritative manner. The treatment is practical in orientation, keeping in mind the needs of the users. Theory is included only where required for an understanding of the topic.

  • 177.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Ninham, B.W.
    -Research School of Physical Sciences and Engineering Australian National University.
    Energy of an ion crossing a low dielectric membrane: the role of dispersion self-free energy2005Ingår i: Biophysical Chemistry, ISSN 0301-4622, E-ISSN 1873-4200, Vol. 114, s. 95-101Artikel i tidskrift (Refereegranskat)
  • 178.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Ninham, B.W.
    Australian National University, Canberra.
    Why pH titration in lysozyme suspensions follow a Hofmeister series2006Ingår i: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 291, s. 24-29Artikel i tidskrift (Refereegranskat)
  • 179.
    Boström, Mathias
    et al.
    Royal Institute Technology, Sweden.
    Persson, Clas
    Royal Institute Technology, Sweden.
    Ninham, Barry W
    Australian National University, Australia.
    Norman, Patrick
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Beräkningsfysik. Linköpings universitet, Tekniska högskolan.
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Resonance interaction induced by metal surfaces catalyzes atom-pair breakage2013Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 87, nr 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present the theory for retarded resonance interaction between two identical atoms at arbitrary positions near a metal surface. The dipole-dipole resonance interaction force that binds isotropically excited atom pairs together in free space may turn repulsive close to an ideal (totally reflecting) metal surface. On the other hand, close to an infinitely permeable surface it may turn more attractive. We illustrate numerically how the dipole-dipole resonance interaction between two oxygen atoms near a metal surface may provide a repulsive energy of the same order of magnitude as the ground-state binding energy of an oxygen molecule. As a complement we also present results from density-functional theory.

  • 180.
    Boström, Mathias
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Persson, Clas
    Royal Institute Technology, Sweden .
    Parsons, Drew F.
    Australian National University, Australia .
    Ellingsen, Simen A.
    Norwegian University of Science and Technology, Norway .
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Atmospheric water droplets can catalyse atom pair break-up via surface-induced resonance repulsion2013Ingår i: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 101, nr 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present the theory for a retarded resonance interaction between two identical atoms near a dielectric surface. In free space the resonance interaction between isotropically excited atom pairs is attractive at all atom-atom separations. We illustrate numerically how this interaction between oxygen, sulphur, hydrogen, or nitrogen atom pairs may turn repulsive near water droplets. The results provide evidence of a mechanism causing excited state atom pair breakage to occur in the atmosphere near water droplets.

  • 181.
    Boström, Mathias
    et al.
    Royal Institute of Technology, Stockholm, Sweden, EU.
    Persson, Clas
    University of Oslo, Norway.
    Sernelius, Bo E.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Casimir force between atomically thin gold films2013Ingår i: European Physical Journal B: Condensed Matter Physics, ISSN 1434-6028, E-ISSN 1434-6036, Vol. 86, s. 43-46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have used density functional theory to calculate the anisotropic dielectric functions forultrathin gold sheets (composed of 1, 3, 6, and 15 atomic layers). Such films are important components innano-electromechanical systems. When using correct dielectric functions rather than bulk gold dielectricfunctions we predict an enhanced attractive Casimir-Lifshitz force (at most around 20%) between twoatomically thin gold sheets. For thicker sheets the dielectric properties and the corresponding Casimirforces approach those of gold half-spaces. The magnitude of the corrections that we predict should, withinthe today’s level of accuracy in Casimir force measurements, be clearly detectable.

  • 182.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Sernelius, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Comment on "Calculation of the Casimir force between imperfectly conducting plates"2000Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 61, nr 4Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    In a recent paper [Phys. Rev. A 59, R3149 (1999)] Lamoreaux reported calculations of the Casimir force. The experimentally found permittivity was used in the calculations. Large deviations were found between numerically evaluated forces and forces derived from a series expanded plasma model. We would like to comment on a few results presented in this work. First, we claim that important features of the imaginary component of the permittivity of copper, presented in Fig. 1(a) are due to the interpolation procedure and are not caused by physical phenomena. These features influence the calculated permittivity for imaginary frequencies, which is the quantity used to calculate the Casimir attraction. Second, we discuss the extrapolation procedure used for low frequencies. The results depend substantially on how this extrapolation is performed.

  • 183.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Sernelius, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Entropy of the Casimir effect between real metal plates2004Ingår i: Physica A: Statistical Mechanics and its Applications, ISSN 0378-4371, E-ISSN 1873-2119, Vol. 339, nr 01-Feb, s. 53-59Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We first derive the zero-and-finite-temperature dispersion-forces in terms of changes in the energy of the electromagnetic normal modes of the system. We then use this to evaluate the entropy of the electromagnetic normal modes for the "Casimir system" consisting of two metal plates. We demonstrate that this entropy obeys the Nernst heat theorem. (C) 2004 Elsevier B.V. All rights reserved.

  • 184.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Sernelius, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Fractional van der Waals interaction between thin metallic films2000Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 61, nr 3, s. 2204-2210Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The van der Waals (vdW) interaction between thin metallic films varies with separation as the separation to a fractional power. This is in contrast to the usual integer-power separation dependence between objects such as atoms, dielectric films, or thick metallic films. We have calculated the free energy of attraction between sheets of gold, silver, copper, beryllium, and tungsten numerically using experimentally found dielectric functions. The results are compared with the corresponding analytical results obtained using simple model dielectric functions. We have investigated how thin the metallic films must be in order for the fractional vdW interaction to be present. To our knowledge, fractional vdW interaction has not yet been confirmed experimentally.

  • 185.
    Boström, Mathias
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Repulsive van der Waals forces due to hydrogen exposure on bilayer graphene2012Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 85, nr 1, s. 012508-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider the effect of atomic hydrogen exposure to a system of two undoped sheets of graphene grown near a silica surface (the first adsorbed to the surface and the second freestanding near the surface). In the absence of atomic hydrogen, the van der Waals force between the sheets is attractive at all separations, causing the sheets to come closer together. However, with the addition of atomic hydrogen between the sheets, the long-range van der Waals interaction turns repulsive at a critical concentration. The underlying triple layer structure (SiO(2)-atomic hydrogen gas-air) gives rise to a long-range repulsion that at large-enough separations dominates over the more rapidly decaying attraction between the two-dimensional undoped graphene sheets (and between the outer graphene sheet and SiO(2)). This may be an avenue to tune the separation between two graphene sheets with the gas concentration. The doping of the graphene layers increases the attractive part of the interaction and hence reduces the net repulsive interaction.

  • 186.
    Boström, Mathias
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Retardation-enhanced van der Waals force between thin metal films2000Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 62, nr 11, s. 7523-7526Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We recently investigated the van der Waals force between thin metal films. Under certain conditions this force decrease with separation to a fractional power. In the present work we use optical data of metals and the zero-temperature Lifshitz formalism to demonstrate a retardation effect. The retarded attraction between thin metal films may be larger than the nonretarded attraction. This property is related to a comparatively weak retardation dependence of the energy that originates from the transverse magnetic modes. At separations where the transverse electric modes give a significant contribution, the net effect can actually be an increased attraction. This effect vanishes with increasing film thickness and with increasing dissipation.

  • 187.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Sernelius, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Temperature effects on the Casimir attraction between a pair of quantum wells2000Ingår i: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 51, s. 287-297Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present calculations of the free energy of attraction between two quantum wells in which the wells are treated as strictly two-dimensional metallic sheets. The van der Waals force exhibits fractional separation dependence in this system. This is in contrast to the usual integer separation dependence. We have performed numerical calculations at different temperatures and with different carrier densities. Except at very low temperatures thermal effects will be a dominating source of attraction. We have determined temperature criteria that must be fulfilled for the fractional separation dependence to be observable. Thermal corrections will be important already at temperatures less than 1 K. We further make some comments on a recent measurement of the Casimir force.

  • 188.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Sernelius, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Thermal effects on the Casimir force in the 0.1-5 mu m range2000Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 84, nr 20, s. 4757-4760Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The vacuum stresses between a metal half-space and a metal sphere were recently measured at room temperature, in the 0.6-6 mu m range, with an estimated accuracy of 5%. In the interpretation it was assumed that the accuracy was not good enough for observing any thermal effects. We claim that thermal effects are important in this separation range and back up this claim with numerical calculations of the Casimir force at zero temperature and at 300 K, based on tabulated optical data of gold, copper, and aluminum. The effects of dissipation and temperature are investigated and we demonstrate the importance of considering these two corrections together.

  • 189.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Sernelius, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    van der Waals energy of an atom in the proximity of thin metal films2000Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 61, nr 5, s. art. no.-052703Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The van der Waals energy of a ground-state atom (or molecule) placed between two metal films is calculated at finite temperature. The attraction between thin metal films and a polarizable object can have half-integer separation dependence. This is in contrast to the usual integer separation dependence, shown for instance in the attraction between an atom and a solid surface. We examine how film thickness, retardation, and temperature influence the interaction. To illustrate the effect of finite thickness of the metal film we calculated the van der Waals energy of ground-state hydrogen and helium atoms, and hydrogen molecules, between thin silver films. We finally, briefly, discuss the possibility to measure this effect.

  • 190.
    Boström, Mathias
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Baldissera, Gustavo
    Royal Institute of Technology.
    Persson, Clas
    Royal Institute of Technology.
    Ninham, Barry W
    Australian National University.
    Casimir-Lifshitz interaction between ZnO and SiO2 nanorods in bromobenzene turns repulsive at intermediate separations due to retardation effects2012Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 85, nr 4, s. 044702-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider the interaction between a ZnO nanorod and a SiO2 nanorod in bromobenzene. Using optical data for the interacting objects and ambient we calculate the force (from short-range attractive van der Waals force to intermediate-range repulsive Casimir-Lifshitz force to long-range entropically driven attraction). The nonretarded van der Waals interaction is attractive at all separations. We demonstrate a retardation-driven repulsion at intermediate separations. At short separations (in the nonretarded limit) and at large separations (in the classical limit) the interaction is attractive. These effects can be understood from an analysis of multiple crossings of the dielectric functions of the three media as functions of imaginary frequencies.

  • 191.
    Boström, Mathias
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Brevik, Iver
    Norwegian University of Science and Technology.
    Ninham, Barry W
    Australian National University.
    Retardation turns the van der Waals attraction into a Casimir repulsion as close as 3 nm2012Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 85, nr 1, s. 010701-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Casimir forces between surfaces immersed in bromobenzene have recently been measured by Munday et al. [Nature (London) 454, 07610 (2009)]. Attractive Casimir forces were found between gold surfaces. The forces were repulsive between gold and silica surfaces. We show the repulsion is due to retardation effects. The van der Waals interaction is attractive at all separations. The retardation-driven repulsion sets in at around 3 nm. To our knowledge, retardation effects have never been found at such a small distance before. Retardation effects are usually associated with large distances.

  • 192.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Tavares, Frederico W.
    Universidade Federal do Rio de Janeiro.
    Ninham, Barry W.
    Australian National University.
    Prausnitz, John M.
    University of California and Lawrence Berkeley National Lab..
    Effect of Salt Identity on the Phase Diagram for a Globular Protein in Aqueous Electrolyte Solution2006Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 110, s. 24757-24760Artikel i tidskrift (Refereegranskat)
  • 193.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Tavares, F.W.
    Escola de Química Universidade Federal do Rio de Janeiro.
    Bratko, D.
    Department of Chemistry Virginia Commonwealth University.
    Ninham, B.W.
    Research School of Physical Sciences and Engineering Australien National University.
    Ion specific interactions between pairs of nanometer ized particles in aqueous solutions2006Ingår i: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 133, s. 74-77Artikel i tidskrift (Refereegranskat)
  • 194.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Tavares, F.W.
    Escola de Química, Universidade Federal do Rio de Janeiro, Brazil.
    Bratko, D.
    Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284.
    Ninham, B.W.
    Research School of Physical Sciences and Engineering, Australian National University, Canberra 0200, Australia.
    Specific ion effects in solutions of globular proteins: Comparison between analytical models and simulation2005Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, nr 51, s. 24489-24494Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Monte Carlo simulations have been performed for ion distributions outside a single globular macroion and for a pair of macroions, in different salt solutions. The model that we use includes both electrostatic and van der Waals interactions between ions and between ions and macroions. Simulation results are compared with the predictions of the Ornstein-Zernike equation with the hypernetted chain closure approximation and the nonlinear Poisson-Boltzmann equation, both augmented by pertinent van der Waals terms. Ion distributions from analytical approximations are generally very close to the simulation results. This demonstrates that properties that are related to ion distributions in the double layer outside a single interface can to a good approximation be obtained from the Poisson-Boltzmann equation. We also present simulation and integral equation results for the mean force between two globular macroions (with properties corresponding to those of hen-egg-white lysozyme protein at pH 4.3) in different salt solutions. The mean force and potential of mean force between the macroions become more attractive upon increasing the polarizability of the counterions (anions), in qualitative agreement with experiments. We finally show that the deduced second virial coefficients agree quite well with experimental results. © 2005 American Chemical Society.

  • 195.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Tavares, F.W.
    Universidade Federal da Rio de Janeiro, Brazil.
    Finet, S.
    ESRF, BP 220, Grenoble.
    Skouri-Panet, F.
    LMCP, Paris.
    Tardieu, A
    P6-PBSF-IM, Paris.
    Ninham, B.W.
    Australian National University Canberra.
    Why forces between proteins follow different Hofmeister series fo pH above and below pI2005Ingår i: Biophysical Chemistry, ISSN 0301-4622, E-ISSN 1873-4200, Vol. 117, s. 217-224Artikel i tidskrift (Refereegranskat)
  • 196.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Williams, DRM
    Ninham, BW
    Special ion effects: Why the properties of lysozyme in salt solutions follow a Hofmeister series2003Ingår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 85, nr 2, s. 686-694Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Protein solubility in aqueous solutions depends in a complicated and not well understood way on pH, salt type, and salt concentration. Why for instance does the use of two different monovalent salts, potassium thiocyanate and potassium chloride, produce such different results? One important and previously neglected source of ion specificity is the ionic dispersion potential that acts between each ion and the protein. This attractive potential is found to be much stronger for SCN- than it is for Cl-. We present model calculations, performed within a modified ion-specific double-layer theory, that demonstrate the large effect of including these ionic dispersion potentials. The results are consistent with experiments performed on hen egg-white lysozymes and on neutral black lipid membranes. The calculated surface pH and net lysozyme charge depend strongly on the choice of anion. We demonstrate that the lysozyme net charge is larger, and the corresponding Debye length shorter, in a thiocyanate salt solution than in a chloride salt solution. Recent experiments have suggested that pK(a) values of histidines depend on salt concentration and on ionic species. We finally demonstrate that once ionic dispersion potentials are included in the theory these results can quantitatively be reinterpreted in terms of a highly specific surface pH (and a salt-independent pK(a)).

  • 197.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Williams, D.R.M.
    Research School of Physical Sciences and Engineering, Australian National University, Canberra 0200, Australia.
    Ninham, B.W.
    Research School of Physical Sciences and Engineering, Australian National University, Canberra 0200, Australia, Departments of Chemistry, Universities of Florence, Italy,.
    Specific ion effects: Role of salt and buffer in protonation of cytochrome c2004Ingår i: The European Physical Journal E Soft matter, ISSN 1292-8941, E-ISSN 1292-895X, Vol. 13, nr 3, s. 239-245Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Changes in background salt and buffer are known to influence the properties of proteins. The reasons have remained obscure. The challenge posed by many such problems is this. Can physical chemistry contribute any predictive quantitative insights to what is in effect the simplest macromolecular solution behavior? Or must all remain specific? Our thesis is that it can. For definiteness we consider here as an illustrative example: surface pH and protonation equilibria of cytochrome c. We demonstrate an important role for ionic dispersion forces, missing from previous theoretical treatments. Unlike charge interactions these are different for each ionic species, and act between a protein and both salt and buffer ions. The charge of proteins depends not only on pH, ionic charge, and salt concentration. Taking ionic dispersion forces into account goes some way towards explaining the dependence on ionic species. We demonstrate why the addition of buffer can have profound effects, including reversal of the salt dependence of the protein charge. © EDP Sciences/ Società Italiana di Fisica/ Springer-Verlag 2004.

  • 198.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Williams, D.R.M.
    Department of Applied Mathematics, Research School of Physical Sciences, Australian National University, Canberra, ACT 0200, Australia.
    Ninham, B.W.
    Department of Applied Mathematics, Research School of Physical Sciences, Australian National University, Canberra, ACT 0200, Australia.
    Specific ion effects: The role of co-ions in biology2003Ingår i: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 63, nr 4, s. 610-615Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Co-ions are as essential in biological systems as they are ignored. The purpose of this letter is to demonstrate the importance of including ionic dispersion potentials acting between ions and interfaces in any realistic theoretical modeling of biological systems. We demonstrate through a well-known biological example that co-ion effects can be understood once these previously ignored forces are included. Experiments have in the past revealed that addition of salt solutions with different co-ions give fundamentally different results for the formation of meta 2 rhodopsin (which is involved in dim light vision). For systems with low salt concentrations, addition of salt favors the formation of meta 1 rhodopsin. Exactly the opposite is observed in high-concentration salt solutions. This is true even after surface pH. effects have been screened out with the addition of 0.5 M sodium acetate buffer. A theoretical explanation for the role of co-ions behind this effect is here given in terms of ionic dispersion potentials and ion specific surface pH.

  • 199.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Williams, DRM
    Ninham, BW
    Why the properties of proteins in salt solutions follow a Hofmeister series2004Ingår i: Current Opinion in Colloid & Interface Science, ISSN 1359-0294, E-ISSN 1879-0399, Vol. 9, nr 01-Feb, s. 48-52Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The physical properties of hen-egg-white lysozyme, and other globular protein, in aqueous solutions depend in a complicated and unexplained way on pH, salt type and salt concentration. One important and previously neglected source of ion specificity is the ionic dispersion potential that acts between each ion and the protein. We present model calculations, performed within a modified ion-specific double layer theory, that demonstrate the large effect of including these ionic dispersion potentials. (C) 2004 Elsevier Ltd. All rights reserved.

  • 200.
    Boström, Mathias
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Williams, DRM
    Stewart, PR
    Ninham, BW
    Hofmeister effects in membrane biology: The role of ionic dispersion potentials2003Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics: Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, ISSN 1063-651X, E-ISSN 1095-3787, Vol. 68, nr 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Membrane biology is notorious for its remarkable, and often strong dependence on the supposedly irrelevant choice of ion pair of background salt solution. While experimentally well known, there has been no progress towards any real theoretical understanding until very recently. We have demonstrated that an important source behind these Hofmeister effects is the ionic excess polarizabilities of ions in solution. Near an interface an ion experiences not only an electrostatic potential, but also a highly specific ionic dispersion potential. At biological concentrations (around 0.1M and higher) when the electrostatic contribution is highly screened this ionic dispersion potential has a dominating influence. We present the result of model calculations for the interfacial tension and surface potential that demonstrates that inclusion of ionic dispersion potentials is an essential step towards predictive theories. Our results are compared with experimental surface and zeta potential measurements on phospholipid bilayers, zirconia, and cationic micelles.

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