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  • 1. Ainalem, M. L.
    et al.
    Campbell, R. A.
    Khalid, S.
    Gillams, R .J.
    Rennie, Adrian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Nylander, T.
    On the Ability of PAMAM Dendrimers and Dendrimer/DNA Aggregates To Penetrate POPC Model Biomembranes2010In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 114, no 21, p. 7229-7244Article in journal (Refereed)
    Abstract [en]

    Poly(amido amine) (PAMAM) dendrimers have previously been shown, as cationic condensing agents of DNA, to have high potential for nonviral gene delivery. This study addresses two key issues for gene delivery: the interaction of the biomembrane with (i) the condensing agent (the cationic PAMAM dendrimer) and (ii) the corresponding dendrimer/DNA aggregate. Using in situ null ellipsometry and neutron reflection, parallel experiments were carried out involving dendrimers or generations 2 (G2), 4 (G4), and 6 (G6). The study demonstrates that free dendrimers of all three generations were able to traverse supported palmitoyloleoylphosphatidylcholine (POPC) bilayers deposited on silica surfaces. The model biomembranes were elevated front the solid surfaces upon dendrimer penetration, which offers a promising new way to generate more realistic model biomembranes where the contact with the supporting surface is reduced and where aqueous cavities are present beneath the bilayer. The largest dendrimer (GO) induced partial bilayer destruction directly upon penetration, whereas the smaller dendrimers (G2 and G4) leave the bilayer intact, so we propose that lower generation dendrimers have greater potential as transfection mediators. In addition to the experimental observations, coarse-grained simulations on the interaction between generation 3 (03) dendrimers and POPC bilayers were performed in the absence and presence of a bilayer-supporting negatively charged surface that emulates the support. The simulations demonstrate that G3 is transported across free-standing POPC bilayers by direct penetration and not by endocytosis. The penetrability was, however, reduced in the presence of a surface, indicating that the membrane transport observed experimentally was not driven solely by the surface. The experimental reflection techniques were also applied to dendrimer/DNA aggregates of charge ratio = 0.5, and while G2/DNA and G4/DNA aggregates interact with POPC bilayers. G6/DNA displays no such interaction. These results indicate that, in contrast to free dendrimer molecules, dendrimer/DNA aggregates of low charge ratios are not able to traverse a membrane by direct penetration.

  • 2.
    Berts, Ida
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Fragneto, Giovanna
    Institut Laue-Langevin.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Tuning the density profile of surface-grafted hyaluronan and the effect of counter-ions2013In: European Physical Journal E, ISSN 1292-8941, Vol. 36, no 7, p. 70-Article in journal (Refereed)
    Abstract [en]

    The present paper investigates the structure and composition of grafted sodium hyaluronanat a solid-liquid interface using neutron reflection. The solvated polymer at the surface could be described with a density profile that decays exponentially towards the bulk solution. The density profileof the polymer varied depending on the deposition protocol. A single-stage deposition resulted in denser polymer layers, while layers created with a two-stage deposition process were more diffuse and had an overall lower density. Despite the diffuse density profile, two-stage deposition leads to a highersurface excess. Addition of calcium ions causes a strong collapse of the sodium hyaluronan chains, increasing the polymer density near the surface. This effect is more pronounced on the sample prepared by two-stage deposition due to the initial less dense profile. This study provides an understanding at a molecular level of how surface functionalization alters the structure and howsurface layers respond to changes in calcium ions in the solvent.

  • 3.
    Berts, Ida
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry. Inst Laue Langevin, 71 Ave Martyrs,CS 20156, F-38042 Grenoble, France..
    Fragneto, Giovanna
    Inst Laue Langevin, 71 Ave Martyrs,CS 20156, F-38042 Grenoble, France..
    Porcar, Lionel
    Inst Laue Langevin, 71 Ave Martyrs,CS 20156, F-38042 Grenoble, France..
    Hellsing, Maja S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala Univ, Ctr Neutron Scattering, Box 516, S-75120 Uppsala, Sweden..
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala Univ, Ctr Neutron Scattering, Box 516, S-75120 Uppsala, Sweden..
    Controlling adsorption of albumin with hyaluronan on silica surfaces and sulfonated latex particles2017In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 504, p. 315-324Article in journal (Refereed)
    Abstract [en]

    Polysaccharides are known to modify binding of proteins at interfaces and this paper describes studies of these interactions and how they are modified by pH. Specifically, the adsorption of human serum albumin on to polystyrene latex and to silica is described, focusing on how this is affected by hyaluronan. Experiments were designed to test how such binding might be modified under relevant physiological conditions. Changes in adsorption of albumin alone and the co-adsorption of albumin and hyaluronan are driven by electrostatic interactions. Multilayer binding is found to be regulated by the pH of the solution and the molecular mass and concentration of hyaluronan. Highest adsorption was observed at pH below 4.8 and for low molecular mass hyaluronan (<= 150 kDa) at concentrations above 2 mg ml(-1). On silica with grafted hyaluronan, albumin absorption is reversed by changes in solvent pH due to their strong electrostatic attraction. Albumin physisorbed on silica surfaces is also rinsed away with dilute hyaluronan solution at pH 4.8. The results demonstrate that the protein adsorption can be controlled both by changes of pH and by interaction with other biological macromolecules.

  • 4.
    Berts, Ida
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Gerelli, Yuri
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Structure of polymer and particle aggregates in hydrogel composites2013In: Journal of Polymer Science Part B: Polymer Physics, ISSN 0887-6266, E-ISSN 1099-0488, Vol. 51, no 6, p. 421-429Article in journal (Refereed)
    Abstract [en]

    Knowledge of the structure of a biomaterial is usually vital to control its function. This article provides a structural characterization of a hyaluronan scaffold that has demonstrated good biocompatibility and is used to induce bone regeneration. Hyaluronan hydrogels are appealing materials that can function as a matrix to incorporate both organic and inorganic substances to enhance tissue growth. Because of the intrinsic properties of this swollen matrix, one needs a very sensitive technique that can be applied in situ to determine the organization of the polymers in a gel. Small-angle neutron scattering is used to determine the characteristics of the inhomogeneous structure of the hydrogel both with and without added particles. The results are interpreted using models of structure with two length scales that are beyond the traditional picture of homogeneous gels. The observed structure and the dimensions can explain the previously reported rheological properties of gels containing different amount of polymers. Hydroxyapatite nanoparticles added to the gel are frozen in the gel matrix. We are able to determine the distribution and shape of these particles as they aggregate around the polymer chains. We have also concluded, in this case, that the particle structure is concentration independent. Information about the nanostructure for an applicable biomaterial guides the formulation, preparation, and use that should lead to further understanding of its exploitation.

  • 5.
    Berts, Ida
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Ossipov, Dmitri
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Fragneto, Giovanna
    Institut Laue-Langevin.
    Frisk, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian. R
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Polymeric Smart Coating Strategy for Titanium Implants2014In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 16, no 11, p. 1340-1350Article in journal (Refereed)
    Abstract [en]

    Hyaluronan based hydrogel coatings can mimic extracellular matrix components and incorporate growth factors that can be released during a progressive degradation while new tissue regenerates. This paper describes a structural characterization of a hydrogel coating made of modified hyaluronan polymers and how these coatings interact with bone morphogenetic protein-2 (BMP-2). Quartz crystal microbalance and neutron reflectivity measurements were used for in-situ, real-time measurements of the adsorption properties of polymers and proteins on smooth titanium oxide surfaces that mimic implant products in orthopedics. The adsorption of BMP-2 on a bare titanium oxide surface is compared to that on titanium oxide coated with different chemically modified hyaluronan, the most important being hyaluronan with bisphosphonate groups (HA-BP). The subsequent release of the BMP-2 from these hydrogel coatings could be triggered by calcium ions. The amount of adsorbed protein on the surfaces as well as the amount of released protein both depend on the type of hyaluronan coating. We conclude that HA-BP coated titanium oxide surfaces provide an excellent material for growth factor delivery in-vivo.

  • 6. Cardenas, M.
    et al.
    Arnebrant, T.
    Rennie, Adrian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Physics.
    Fragneto, G.
    Thomas, R. K.
    Lindh, L.
    Human Saliva Forms a Complex Film Structure on Alumina Surfaces2007In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 1, p. 65-69Article in journal (Refereed)
    Abstract [en]

    Films formed from saliva on surfaces are important for the maintenance of oral health and integrity by protection against chemical and/or biological agents. The aim of the present study was to investigate adsorbed amounts, thickness, and structure of films formed from human whole saliva on alumina surfaces by means of in situ ellipsometry, neutron reflectivity, and atomic force microscopy. Alumina (Al2O3, synthetic sapphire) is a relevant and interesting substrate for saliva adsorption studies as it has an isoelectric point close to that of tooth enamel. The results showed that saliva adsorbs rapidly on alumina. The film could be modeled in two layers:  an inner and dense thin region that forms a uniform layer and an outer, more diffuse and thicker region that protrudes toward the bulk of the solution. The film morphology described a uniformly covering dense layer and a second outer layer containing polydisperse adsorbed macromolecules or aggregates.

  • 7. Cubitt, R.
    et al.
    Fragneto, G.
    Ghosh, R. E.
    Rennie, Adrian
    Department of Chemistry, King's College London.
    REFILL 2002: Advances in the study of interfaces with neutron reflection2003In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 19, no 19, p. 7685-7687Article in journal (Refereed)
  • 8. Hagelstein, M.
    et al.
    Vollath, D.
    Szabo, D. V.
    Borowski, M.
    Ferrero, C.
    Fitch, A. N.
    Boesecke, P.
    Rennie, Adrian
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, The Studsvik Neutron Research Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Neutron Research.
    Characterization of PMA-coated, nanocrystalline gamma-Fe2O3 with synchrotron radiation techniques2002In: European Physical JournalArticle in journal (Refereed)
  • 9.
    Hellsing, Maja
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Hughes, Arwel V.
    Adsorption of Aerosol-OT to Sapphire: Lamellar Structures Studied with Neutrons2011In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 27, no 8, p. 4669-4678Article in journal (Refereed)
    Abstract [en]

    The adsorption of sodium bis 2-ethylhexyl sulfosuccinate, NaAOT, to a sapphire surface from aqueous solution has been studied by neutron reflection at concentrations above the critical micelle concentration (cmc). Complementary measurements of the bulk structure were made with small-angle neutron scattering and grazing incidence small-angle neutron scattering. At a concentration of about 1% wt (10 X cmc), lamellar phase NaAOT was observed both at the surface and in the bulk. The structure seen at the interface for a solution of 2% wt NaAOT is a 35 +/- 2 angstrom thick bilayer adsorbed to the sapphire surface at maximum packing density, followed by an aligned stack of fluctuating bilayers of thickness 51 +/- 2 angstrom and with an area per molecule of 40 +/- 2 angstrom(2). Each bilayer is separated by a water: at 25 degrees C, this layer is 148 +/- 2 angstrom. A simple model for the reflectivity from fluctuating layers is presented, and for 2.0% wt NaAOT the fluctuations were found to have an amplitude of 25 +/- 5 angstrom. The temperature sensitivity of the structure at the surface was investigated in the range 15-30 degrees C. The effect of temperature was pronounced, with the solvent layer becoming thinner and the volume occupied by the NaAOT molecules in a bilayer increasing with temperature. The amplitude of the fluctuations, however, is approximately temperature independent in this range. The adsorption of NaAOT at the sapphire surface resembles that previously found at hydrophilic and hydrophobic silica surfaces. The coexisting bulk lamellar phase has a spacing of layers similar to that observed at the surface. These observations are an indication that the major driving force for adsorption is self-assembly, independent of the chemical nature of the interface.

  • 10.
    Hellsing, Maja S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Kapaklis, Vassilios
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Hughes, Arwel V.
    Porcar, Lionel
    Crystalline order of polymer nanoparticles over large areas at solid/liquid interfaces2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 22, p. 221601-Article in journal (Refereed)
    Abstract [en]

    We report on the formation of large two-dimensional domains (about 20 cm2) of oriented and ordered structures of polystyrene particles dispersed in water at a solid/liquid interface.  Gentle flow of the dispersed sample into the holder at a shear strain rate of about 0.1 s−1 caused particles at the air/latex meniscus to self-assemble in a regular structure on both solid silica or alumina surfaces.  Scattering experiments show that the particle separation at the surface was the same as in the bulk and determined by repulsion arising from the charges on the particles.  Close-packed planes formed parallel to the interface.

  • 11.
    Hellsing, Maja S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Kwaambwa, Habauka M.
    Nermark, Fiona M.
    Nkoane, Bonang B. M.
    Jackson, Andrew J.
    Wasbrough, Matthew J.
    Berts, Ida
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Porcar, Lionel
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Structure of flocs of latex particles formed by addition of protein from Moringa seeds2014In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 460, p. 460-467Article in journal (Refereed)
    Abstract [en]

    Proteins extracted from the seeds of Moringa trees are effective flocculents for particles dispersed in water and are attractive as a natural and sustainable product for use in water purification. Studies with a model system consisting of polystyrene latex particles have shown that the protein adsorbs to the surface and causes flocculation as unusually dense aggregates. Small-angle neutron scattering that exploits contrast matching of deuterated latex particles dispersed in D2O to highlight bound protein has shown that the adsorbed amount reaches about 3 mg m(-2). The particles form very compact flocs that are characterized by fractal dimensions that approach the theoretical maximum of 3. Ultra small-angle neutron scattering allows these flocs to be characterized for a range of particle and protein concentrations. Proteins from two species of Moringa trees were investigated. The protein from Moringa stenopetala seeds gave rise to slightly lower fractal dimensions compared to Moringa oleifera, but still much larger than values observed for conventional ionic or polymeric flocculents that are in the range 1.75-2.3. Compact flocs are desirable for efficient separation of impurities and dewatering of sludge as well as other applications. A trend of increasing fractal dimension with particle concentration was observed when M. stenopetala seed protein was used and this resembles the behaviour predicted in Brownian dynamics simulation of flocculation.

  • 12.
    Hellsing, Maja S.
    et al.
    RISE Res Inst Sweden, Biosci & Mat, Box 5607, SE-11486 Stockholm, Sweden.
    Rennie, A. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rodal, Michael
    Biolin Sci AB, SE-42677 Vastra Frolunda, Sweden.
    Höök, Fredrik
    Chalmers Univ Technol, Dept Appl Phys, SE-41296 Gothenburg, Sweden.
    Charged Polystyrene Nanoparticles Near a SiO2/Water Interface2019In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 35, no 1, p. 222-228Article in journal (Refereed)
    Abstract [en]

    Quartz crystal microbalance with dissipation (QCM-D) monitoring is used to investigate the adsorption processes at liquid-solid interfaces and applied increasingly to characterize viscoelastic properties of complex liquids. Here, we contribute new insights into the latter field by using QCM-D to investigate the structure near the interface and the high-frequency viscoelastic properties of charge-stabilized polystyrene particles (radius 37 nm) dispersed in water. The study reveals changes with increasing ionic strength and particle concentration. Replacing water with a dispersion is usually expected to give rise to a decrease in frequency, f. Increases in both f and dissipation, D, were observed on exchanging pure water for particle dispersions at a low ionic strength. The QCM-D data are well-represented by a viscoelastic model, with viscosity increasing from 1.0 to 1.3 mPa s as the particle volume fraction changes from 0.005 to 0.07. This increase, higher than that predicted for noninteracting dispersions, can be explained by the charge repulsion between the particles giving rise to a higher effective volume fraction. It is concluded that the polystyrene particles did not adhere to the solid surface but rather were separated by a layer of pure dispersion medium. The QCM-D response was successfully represented using a viscoelastic Kelvin-Voigt model, from which it was concluded that the thickness of the dispersion medium layer was of the order of the particle-particle bulk separation, in the range of 50-250 nm, and observed to decrease with both particle concentration and addition of salt. Similar anomalous frequency and dissipation responses have been seen previously for systems containing weakly adherent colloidal particles and bacteria and understood in terms of coupled resonators. We demonstrate that surface attachment is not required for such phenomena to occur, but that a viscoelastic liquid separated from the oscillating surface by a thin Newtonian layer gives rise to similar responses.

  • 13.
    Hellsing, Maja S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Heenan, Richard K.
    Rogers, Sarah E.
    Structure of a large colloidal crystal: controlling orientation and three-dimensional order2012In: RSC Advances, ISSN 2046-2069, Vol. 2, no 18, p. 7091-7098Article in journal (Refereed)
    Abstract [en]

    The three-dimensional crystal structure of charge stabilised polystyrene latex in deionised water was investigated by small-angle neutron diffraction. Crystallisation with a grain size of approximately 1 x 1 cm(2) was observed when the sample was flowed gently in to a 2 mm path cell. Bragg scattering peaks arising from the structure were observed under rotation about three perpendicular axes of the sample. The diffraction patterns indicate clearly that there is a cubic close packed structure with a 110 axis perpendicular to the cell wall. Rotations in small steps show large changes and indicate that the crystal is well oriented and has three-dimensional order. The crystal orientation was controlled by the meniscus and direction of flow when filling the cell.

  • 14.
    Hellsing, Maja S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Hughes, Arwel V.
    Effect of Concentration and Addition of Ions on the Adsorption of Aerosol-OT to Sapphire2010In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 26, no 18, p. 14567-14573Article in journal (Refereed)
    Abstract [en]

    Aerosol-OT (sodium bis 2-ethylhexyl sulfosuccinate or NaAOT) adsorbs to hydrophilic sapphire solid surfaces The structure of the formed bilayer has been determined over the concentration range 0 2-7 4mM NaAOT It was found that the hydrocarbon tails pack at maximum packing limit at very low concentrations, and that the thickness of the bilayer was concentration-independent The adsorption was found to increase with concentration, with the surfactant molecules packing closer laterally The area per molecule was found to change from 138 +/- 25 to 51 +/- 4 angstrom(2) over the concentration range studied, with the thickness of the layer being constant at 33 2 A Addition of small amounts of salt was found to increase the surface excess, with the bilayer being thinner with a slightly larger area per molecule Addition of different salts of the same valency was found to have a very similiar effect, as had the addition of NaOH and HCl Hence, the effects of adding acid or base should be considered an effect of ionic strength rather than an effect of pH Adsorption of NaAOT to the sapphire surface that carries an opposite charge to the anionic surfactant is similar in many respects to the adsorption reported previously for hydrophilic and hydrophobic silica surfaces This suggests that the adsorption of NaAOT to a sui face is driven primarily by NaAOT self-assembly rather than effects of electrostatic at to the interface

  • 15.
    Hellsing, Maja S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Porcar, Lionel
    Englund, Carl-Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Scattering from Dilute and Lamellar Phase Solutions of Aerosol-OT Simultaneous Probe of Surface Structures and Bulk2011In: Trends in colloid andinterface science XXIV / [ed] Viktor Starov, Karel Procházka, 2011, Vol. 138, p. 139-142Conference paper (Refereed)
    Abstract [en]

    The benefits of simultaneous studies of adsorbed layers and bulk structures are shown for solutions of the surfactant Aerosol-OT. Above the critical micelle concentration, Aerosol-OT forms an aligned lamellar phase at the sapphire/solution interface which is in equilibrium with a bulk phase that consists of coexisting micellar solution and dispersed lamellar phase. Measurements of the aligned surface layers and the bulk scattering from a 2% wt solution by grazing incidence and small-angle neutron scattering show that the bulk consist of lamellar structures with the same d-spacing as seen at the surface but without the surface induced alignment. The surface lamellar structure corresponds to a 10% volume fraction for a 2% wt bulk which implies that there must be coexistence of regions of different concentration. Scattering patterns measured in grazing incidence geometry clearly show the relative contributions from small-angle scattering and specular reflectivity.

  • 16.
    Hemming, Joanna M.
    et al.
    Univ London, Dept Biol Sci, Birkbeck Coll, London WC1E 7HX, England.;Univ London, Inst Struct & Mol Biol, Birkbeck Coll, London WC1E 7HX, England..
    Hughes, Brian R.
    Univ London, Dept Biol Sci, Birkbeck Coll, London WC1E 7HX, England.;Univ London, Inst Struct & Mol Biol, Birkbeck Coll, London WC1E 7HX, England..
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Tomas, Salvador
    Univ London, Dept Biol Sci, Birkbeck Coll, London WC1E 7HX, England.;Univ London, Inst Struct & Mol Biol, Birkbeck Coll, London WC1E 7HX, England..
    Campbell, Richard A.
    Inst Max Von Laue Paul Langevin, C520156, F-38042 Grenoble 9, France..
    Hughes, Arwel V.
    STFC Rutherford Appleton Lab, ISIS Pulsed Neutron & Muon Source, Didcot OX11 0QX, Oxon, England..
    Arnold, Thomas
    Diamond Light Source, Didcot OX11 0DE, Oxon, England..
    Botchway, Stanley W.
    STFC Rutherford Appleton Lab, STFC Lasers Sci Facil, Cent Laser Facil, Didcot OX11 0FA, Oxon, England..
    Thompson, Katherine C.
    Univ London, Dept Biol Sci, Birkbeck Coll, London WC1E 7HX, England.;Univ London, Inst Struct & Mol Biol, Birkbeck Coll, London WC1E 7HX, England..
    Environmental Pollutant Ozone Causes Damage to Lung Surfactant Protein B (SP-B)2015In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 54, no 33, p. 5185-5197Article in journal (Refereed)
    Abstract [en]

    Lung surfactant protein B (SP-B) is an essential protein found in the surfactant fluid at the air water interface of the lung. Exposure to the air pollutant ozone could potentially damage SP-B and lead to respiratory distress. We have studied two peptides, one consisting of the N-terminus of SP-B [SP-B(1-25)] and the other a construct of the N- and C-termini of SP-B [SP-B-(1-25,B-63-78)], called SMB. Exposure to dilute levels of ozone (similar to 2 ppm) of monolayers of each peptide at the air water interface leads to a rapid reaction, which is evident from an increase in the surface tension. Fluorescence experiments revealed that this increase in surface tension is accompanied by a loss of fluorescence from the tryptophan residue at the interface. Neutron and X-ray reflectivity experiments show that, in contrast to suggestions in the literature, the peptides are not solubilized upon oxidation but rather remain at the interface with little change in their hydration. Analysis of the product material reveals that no cleavage of the peptides occurs, but a more hydrophobic product is slowly formed together with an increased level of oligomerization. We attributed this to partial unfolding of the peptides. Experiments conducted in the presence of phospholipids reveal that the presence of the lipids does not prevent oxidation of the peptides. Our results strongly suggest that exposure to low levels of ozone gas will damage SP-B, leading to a change in its structure. The implication is that the oxidized protein will be impaired in its ability to interact at the air water interface with negatively charged phosphoglycerol lipids, thus compromising what is thought to be its main biological function.

  • 17. Henderson, M. J.
    et al.
    Gibaud, A.
    Bardeau, J.-F.
    Rennie, A. R.
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, The Studsvik Neutron Research Laboratory.
    White, J. W.
    A zirconium oxide film self-assembled at the air-water interface2005In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 357, no 1-2, p. 27-33Article in journal (Refereed)
  • 18. Henderson, M. J.
    et al.
    Hawley, A. M.
    Rennie, Adrian
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Gibaud, A.
    Bardeau, J-F.
    White, J. W.
    Titanium Oxide Film Self-Assembled at the Air/Water Interface’2006In: Chemical PhysicsArticle in journal (Refereed)
  • 19. Henderson, M. J.
    et al.
    Rennie, Adrian
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, The Studsvik Neutron Research Laboratory.
    Hawley, A. M.
    White, J. W.
    Swelling of a mesostructured zirconium oxide film2006In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 385, p. 713-715Article in journal (Refereed)
    Abstract [en]

    The structural changes that cause the change in interlayer spacing of a surfactant-templated zirconium oxide film have been studied using neutron diffractometry. We report that the film after drying on a glass substrate swells slightly through the addition of benzene by up to 4 Å on a lattice parameter of about 36 Å. The (0 0 1) and (0 0 2) diffraction peak widths, positions and areas of a swollen film were monitored as a function of benzene desorption. Disorder of the lamellar mesophase is considered as a cause of the observed effects on the diffraction signals.

  • 20.
    Jones, Stephanie H.
    et al.
    Royal Holloway Univ London, Dept Earth Sci, Egham TW20 0EX, Surrey, England.;Rutherford Appleton Lab, STFC, Cent Laser Facil, Res Complex Harwell, Didcot OX11 0FA, Oxon, England..
    King, Martin D.
    Royal Holloway Univ London, Dept Earth Sci, Egham TW20 0EX, Surrey, England..
    Ward, Andrew D.
    Rutherford Appleton Lab, STFC, Cent Laser Facil, Res Complex Harwell, Didcot OX11 0FA, Oxon, England..
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Jones, Alex C.
    Royal Holloway Univ London, Dept Earth Sci, Egham TW20 0EX, Surrey, England..
    Arnold, Thomas
    Diamond Light Source, Harwell Campus, Didcot OX11 0DE, Oxon, England..
    Are organic films from atmospheric aerosol and sea water inert to oxidation by ozone at the air-water interface?2017In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 161, p. 274-287Article in journal (Refereed)
    Abstract [en]

    The heterogeneous oxidation of thin films of organic material extracted from real aerosol and sea-water samples was studied at the air-water interface using X-ray reflectivity. Oxidation of thin films of organic material extracted from real aerosol and sea-water is important in further understanding the impact of coated aerosols on the climate of the Earth. Surface active insoluble organic material extracted from the atmosphere was found to form stable films at the air-water interface (thickness measured as 10-14 nm). On exposure of the films to gas-phase ozone, no reaction (or change in the relative scattering length of the interface) was observed, indicating a potential lack of unsaturated organic material in the samples. Gas chromatography and electrospray ionization mass spectrometry showed the presence of saturated compounds in the samples. It is therefore proposed that the amount of unsaturated compounds as compared to saturated compounds in the atmospheric material is so low that the mass spectrometry analyses, as well as gas-phase oxidation are dominated by saturated material. A reaction was observed on exposure of the same films to aqueous phase hydroxyl and nitrate radicals and a film thinning mechanism is proposed to explain the change in scattering length of the film at the air-water interface. It can be suggested tentatively that oxidation by gas-phase ozone is not important in the atmosphere for organic films on aqueous atmospheric aerosol and that further studies should focus on radical induced oxidation of saturated organic material instead of unsaturated proxies that are typically studied.

  • 21. King, M D
    et al.
    Rennie, Adrian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Pfrang, C
    Hughes, A V
    Thompson, K C
    Interaction of nitrogen dioxide (NO2) with a monolayer of oleic acid at the air-water interface - A simple proxy for atmospheric aerosol2010In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 44, no 14, p. 1822-1825Article in journal (Refereed)
    Abstract [en]

    The reactions between atmospheric oxidants and organic amphiphiles at the air water interface of an aerosol droplet may affect the size and critical supersaturation required for cloud droplet formation. We demonstrate that no reaction occurs between gaseous nitrogen dioxide (1000 ppm in air) and a monolayer of an insoluble amphiphile, oleic acid (cis-9-octadecenoic acid), at the air water interface which removes material from the air water interface. We present evidence that the NO2 isomerises the cis-9-octadecenoic (oleic) acid to trans-9-octadecenoic (elaidic) acid. The study presented here is important for future and previous studies of (1) the reaction between the nitrate radical, NO3, and thin organic films as NO2 is usually present in high concentrations in these experimental systems and (2) the effect of NO2 air pollution on the unsaturated fatty acids and lipids found at the air liquid surface of human lung lining fluid.

  • 22. King, Martin D.
    et al.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Thompson, C
    Fisher, N
    Dong, Chuan
    Thomas, K
    Pfrang, Christian
    Hughes, Arwel V.
    Oxidation of oleic acid at the air-water interface and its potential effects on cloud critical supersaturations2009In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 11, no 35, p. 7699-7707Article in journal (Refereed)
    Abstract [en]

    The oxidation of organic films on cloud condensation nuclei has the potential to affect climate and precipitation events. In this work we present a study of the oxidation of a monolayer of deuterated oleic acid (cis-9-octadecenoic acid) at the air-water interface by ozone to determine if oxidation removes the organic film or replaces it with a product film. A range of different aqueous sub-phases were studied. The surface excess of deuterated material was followed by neutron reflection whilst the surface pressure was followed using a Wilhelmy plate. The neutron reflection data reveal that approximately half the organic material remains at the air-water interface following the oxidation of oleic acid by ozone, thus cleavage of the double bond by ozone creates one surface active species and one species that partitions to the bulk (or gas) phase. The most probable products, produced with a yield of similar to(87 +/- 14)%, are nonanoic acid, which remains at the interface, and azelaic acid (nonanedioic acid), which dissolves into the bulk solution. We also report a surface bimolecular rate constant for the reaction between ozone and oleic acid of (7.3 +/- 0.9) x 10(-11) cm(2) molecule s(-1). The rate constant and product yield are not affected by the solution sub-phase. An uptake coefficient of ozone on the oleic acid monolayer of similar to 4 x 10(-6) is estimated from our results. A simple Kohler analysis demonstrates that the oxidation of oleic acid by ozone on an atmospheric aerosol will lower the critical supersaturation needed for cloud droplet formation. We calculate an atmospheric chemical lifetime of oleic acid of 1.3 hours, significantly longer than laboratory studies on pure oleic acid particles suggest, but more consistent with field studies reporting oleic acid present in aged atmospheric aerosol.

  • 23.
    Kwaambwa, Habauka M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Hellsing, Maja
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Adsorption of a Water Treatment Protein from Moringa oleifera Seeds to a Silicon Oxide Surface Studied by Neutron Reflection2010In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 26, no 6, p. 3902-3910Article in journal (Refereed)
    Abstract [en]

    An extract from the seeds of the Moringa oleifera tree that is principally a low molecular mass protein is known to be efficient as a coagulating agent for water treatment. The present paper investigates the adsorption of the purified protein to silica interfaces in order to elucidate the mechanism of its function as a flocculent. Neutron reflection permits the determination of the structure and composition of interfacial layers at the solid/solution interface. Dense layers of protein with about 5.5 mg m(-2) were found at concentrations above 0.025% wt. The overall thickness with a dense layer in excess of 60 angstrom at 0.05 wt % suggests strong co-operative binding rather than single isolated molecules. All ionic surfactant, sodium dodecyl sulfate, was also seen to coadsorb. This strong adsorption of protein in combination with the tendency for the protein to associate suggests a mechanism for destabilizing particulate dispersions to provide filterable water. This call occur even for the protein that has previously been identified as being of low mass (about 7 kDaltons) and thus is unlikely to be efficient in bridging or depletion flocculation.

  • 24.
    Kwaambwa, Habauka M.
    et al.
    Polytech Namibia, Sch Hlth & Appl Sci, Windhoek, Namibia..
    Hellsing, Maja S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Barker, Robert
    Inst Laue Langevin, F-38042 Grenoble 9, France..
    Interaction of Moringa oleifera seed protein with a mineral surface and the influence of surfactants2015In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 448, p. 339-346Article in journal (Refereed)
    Abstract [en]

    The paper describes the adsorption of purified protein from seeds of Moringa olelfera to a sapphire interface and the effects of addition of the anionic surfactant sodium dodecylsulfate (SOS) and the cationic surfactant hexadecyltrimethylammonium bromide (CTAB). Neutron reflection was used to determine the structure and composition of interfacial layers adsorbed at the solid/solution interface. The maximum surface excess of protein was found to be about 5.3 mg m(-2). The protein does not desorb from the solid/liquid interface when rinsed with water. Addition of SDS increases the reflectivity indicating co-adsorption. It was observed that CTAB is able to remove the protein from the interface. The distinct differences to the behavior observed previously for the protein at the silica/water interface are identified. The adsorption of the protein to alumina in addition to other surfaces has shown why it is an effective flocculating agent for the range of impurities found in water supplies. The ability to tailor different surface layers in combination with various surfactants also offers the potential for adsorbed protein to be used in separation technologies.

  • 25.
    Kwaambwa, Habauka M.
    et al.
    Namibia Univ Sci & Technol, Fac Hlth & Appl Sci, Private Bag 13388,13 Starch St, Windhoek, Namibia..
    Hellsing, Maja S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Wasbrough, Matthew J.
    NIST, Ctr Neutron Res, 100 Bur Dr,Stop 6102, Gaithersburg, MD 20899 USA.;Univ Delaware, Chem & Biomol Engn, 150 Acad St, Newark, DE 19716 USA..
    Bleuel, Markus
    NIST, Ctr Neutron Res, 100 Bur Dr,Stop 6102, Gaithersburg, MD 20899 USA..
    Rennie, A. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Salt induced polystyrene latex flocs investigated by neutron scattering2017In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 505, p. 9-13Article in journal (Refereed)
    Abstract [en]

    Studies with a model system consisting of polystyrene latex particles showed that the protein from seeds of Moringa trees adsorbs to the surface and causes flocculation as unusually dense aggregates. In this study, electrolytes sodium chloride (NaCI), ferric chloride (FeCl3) and aluminium sulfate (Al-2(SO4)(3)) have been used to aggregate model polystyrene particles. The study augments previous work using neutron scattering on the flocculation of polystyrene latex with protein from seeds of Moringa trees that had indicated higher floc dimension, df, values as the concentration of particles increased. The measurements were made using ultra small-angle neutron scattering. Generally the fractal dimension, and thus the floc density, increased with particle concentration and salt concentration. Flocculation was apparent at much lower concentrations of FeCl3 and Al-2(SO4)(3) than of NaCI. The values of df were found not to simply scale with ionic strength for the three electrolytes studied with FeCl3 being the most effective flocculating agent.

  • 26.
    Kwaambwa, Habauka M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Interactions of surfactants with a water treatment protein from Moringa oleifera seeds in solution studied by zeta-potential and light scattering measurements2012In: Biopolymers, ISSN 0006-3525, E-ISSN 1097-0282, Vol. 97, no 4, p. 209-218Article in journal (Refereed)
    Abstract [en]

    Protein extracted from Moringa oleifera (MO) seeds has been advocated as a cheap and environmental friendly alternative to ionic flocculants for water purification. However, the nature and mechanism of its interaction with particles in water, as well as with dissolved surface-active molecules, are not well understood. In this article, we report studies of the protein and its interaction with four surfactants using dynamic light scattering (DLS), zeta-potential and turbidity measurements. Zeta-potential measurements identified points of charge reversal and the turbidity and DLS measurements were used to characterize the microstructure and size of protein-surfactant complexes. From the points of charge reversal, it was estimated that 7 anions are required to neutralize the positive charges of each protein molecule at pH 7. For protein mixtures with sodium dodecyl sulfate and dodecyl di-acid sodium salt, the peak in turbidity corresponds to concentrations with a large change in zeta-potential. No turbidity was observed for protein mixtures with either the nonionic surfactant Triton X-100 or the zwitterionic surfactant N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate. Changes of pH in the range 410 have little effect on the zeta-potential, turbidity, and the hydrodynamic radius reflecting the high isoelectric point of the protein. Addition of small amounts of salt has little effect on the size of protein in solution. These results are discussed in the context of the use of the MO protein in water treatment.

  • 27.
    Larsen, Simon R.
    et al.
    Univ Copenhagen, Niels Bohr Inst, Copenhagen, Denmark.
    Hansteen, Marie
    Norwegian Univ Sci & Technol NTNU, Trondheim, Norway.
    Pacakova, Barbara
    Norwegian Univ Sci & Technol NTNU, Trondheim, Norway.
    Theodor, Keld
    Univ Copenhagen, Niels Bohr Inst, Copenhagen, Denmark.
    Arnold, Thomas
    Harwell Sci & Innovat Campus, Diamond Light Source, Fermi Ave, Oxon, England.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Helgesen, Geir
    Inst Energy Technol IFE, Kjeller, Norway.
    Knudsen, Kenneth D.
    Norwegian Univ Sci & Technol NTNU, Trondheim, Norway; Inst Energy Technol IFE, Kjeller, Norway.
    Bordallo, Heloisa N.
    Univ Copenhagen, Niels Bohr Inst, Copenhagen, Denmark; European Spallat Source ERIC, Lund, Sweden.
    Fossum, Jon Otto
    Norwegian Univ Sci & Technol NTNU, Trondheim, Norway.
    Cavalcanti, Leide P.
    Inst Energy Technol IFE, Kjeller, Norway.
    Sample cell for studying liquid interfaces with an in situ electric field using X-ray reflectivity and application to clay particles at oil–oil interfaces2018In: Journal of Synchrotron Radiation, ISSN 0909-0495, E-ISSN 1600-5775, Vol. 25, no Part: 3, p. 915-917Article in journal (Refereed)
    Abstract [en]

    Commissioning results of a liquid sample cell for X-ray reflectivity studies with an in situ applied electrical field are presented. The cell consists of a Plexiglas container with lateral Kapton windows for air-liquid and liquid-liquid interface studies, and was constructed with grooves to accept plate electrodes on the walls parallel to the direction of the beam. Both copper and ITO plate electrodes have been used, the latter being useful for simultaneous optical studies. Commissioning tests were made at the I07 beamline of the Diamond Light Source.

  • 28.
    Li, Ning Ning
    et al.
    Univ Oxford, Dept Chem, Phys & Theoret Chem Lab, S Parks Rd, Oxford OX1 3QZ, England..
    Thomas, Robert K.
    Univ Oxford, Dept Chem, Phys & Theoret Chem Lab, S Parks Rd, Oxford OX1 3QZ, England..
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Neutron reflectometry of anionic surfactants on sapphire: A strong maximum in the adsorption near the critical micelle concentration2016In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 471, p. 81-88Article in journal (Refereed)
    Abstract [en]

    The adsorption of the anionic surfactants, lithium, sodium and cesium dodecylsulfates, and sodium decylsulfonate, on the positively charged C-plane (0001) of sapphire (alumina) has been measured using neutron reflection. For each of the four surfactants there is a strong maximum in the adsorption at about the critical micelle concentration. The maximum becomes more marked from lithium to cesium. The measurements were reproduced over a range of different physical conditions and could not be accounted for in terms of impurities. The maximum is explained quantitatively by using the combination of a mass action model to calculate the mean activity of the surfactant, and a cooperative model of the adsorption (Frumkin), in which saturation of the layer is not attained until well above the critical micelle concentration.

  • 29. Li, Ningning
    et al.
    Thomas, Robert K.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Adsorption of non-ionic surfactants to the sapphire/solution interface: Effects of temperature and pH2012In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 369, p. 287-293Article in journal (Refereed)
    Abstract [en]

    The adsorption of the non-ionic surfactants tetraoxyethylene glycol monododecyl ether (C12EO4), pentaoxyethylene glycol monododecyl ether (C12EO5), and hexaoxyethylene glycol monododecyl ether (C12EO6) to single crystal sapphire substrates has been studied using specular neutron reflection for solutions at the critical micelle concentration. The effects of temperature and pH of the solutions were studied as well as the differences between two different crystal faces, the C and the R planes. At neutral pH, significant adsorption was only observed when the temperature was raised above the cloud temperature. This adsorption was reversible and surfactant was displaced on cooling. Reducing the pH to 3 results in significantly increased adsorption of C12EO5 at 25 degrees C with a central layer consisting mainly of surfactant (about 90%) on the C-plane substrate. A slightly smaller surface excess was observed for the R-plane. This contrasts with the significantly lower density observed even at high temperatures at neutral pH on both substrates. The results suggest that for neutral solutions surfactant association above the cloud point is the primary driving force for adsorption. At low pH, specific interactions with protonated surfaces are important. The structures of the highly hydrated layers are similar to those found for the surfactants at hydrophilic silica surfaces.

  • 30. Li, Ningning
    et al.
    Thomas, Robert K.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Effect of pH, surface charge and counter-ions on the adsorption of sodium dodecyl sulfate to the sapphire/solution interface2012In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 378, p. 152-158Article in journal (Refereed)
    Abstract [en]

    The role of ionic interactions between sodium dodecyl sulfate, SDS, and sapphire surfaces have been studied using specular neutron reflection to determine the structure and composition of adsorbed surfactant layers. Increasing the pH of the solution from 3 to 9 reduces the adsorption by reversing the charge of the alumina. This occurs at lower pH for the R-plane (1 (1) over bar 02) than the C-plane (0001), corresponding to the different points of zero charge. The largest surface excess is about 6.5 mu mol m(-2), the thickness of the adsorbed layer is about 24 angstrom and it contains roughly 20% water. The hydrocarbon tails of the surfactant molecules clearly interpenetrate rather than form an ordered bilayer. The structure is similar in either pure water or in 0.1 M NaCl when the surfactant is at the respective critical micelle concentration. Different structures were seen with lithium and cesium dodecyl sulfate. The CsDS forms dense layers with little or no hydration and a surface excess of about 10.5 mu mol m(-2). The metal cation strongly influences the hydration of the adsorbed surfactant. An overall picture of 'flattened micelles' for the structure of the adsorbed layer is observed.

  • 31. Li, Z. X.
    et al.
    Lu, J. R.
    Thomas, R. K.
    Weller, A.
    Penfold, J.
    Webster, J. R. P.
    Silvia, D. S
    Rennie, Adrian
    Department of Chemistry, King's College London.
    Conformal Roughness in the adsorbed lamellar phase of Aerosol-OT at the air-water and liquid-solid interfaces2001In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 17, no 19, p. 5858-5864Article in journal (Refereed)
  • 32. Linton, Peter
    et al.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Alfredsson, Viveka
    Evolution of structure and composition during the synthesis of mesoporous silica SBA-15 studied by small-angle neutron scattering2011In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 13, no 4, p. 793-799Article in journal (Refereed)
    Abstract [en]

    In-situ time-resolved small-angle neutron scattering (SANS) has been applied for the study of the formation of mesoporous silica SBA-15. The advantage of neutron scattering, compared to X-ray scattering, is the possibility to contrast match i.e. highlight certain parts of the sample. Three different solvents with different scattering contrasts were used for each synthesis. Three different silica sources (tetramethyl orthosilicate, tetraethyl orthosilicate and tetrapropyl orthosilicate) were used and in three cases salts (sodium chloride or sodium bromide) were added prior to addition of the silica source. Hence, the effect of the silica sources and of the salts, on the formation of SBA-15 was investigated. The main focus was on the evolution of the ordered hexagonal structure i.e. investigation of the (10) Bragg peak. In synchrotron SAXS measurements the intensity of the (10) Bragg peak continuously increases during the measurement. However, in the SANS measurements the (10) Bragg peak area decreases with time. The decrease of the (10) peak is highly dependent on the solvent, a larger fraction of D2O in the solvent results in a bigger reduction. The decrease is also more pronounced when salt is present in the synthesis. The reduction of intensity reflects the chemistry in the wall and is explained by the compositional change in the wall during the maturation of the hexagonal order.

  • 33. Linton, Peter
    et al.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Zackrisson, Malin
    Alfredsson, Viveka
    In Situ Observation of the Genesis of Mesoporous Silica SBA-15: Dynamics on Length Scales from 1 nm to 1 mu m2009In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 25, no 8, p. 4685-4691Article in journal (Refereed)
    Abstract [en]

    We report on the mechanism of growth of mesoporous silica (SBA-15, plane group p6m). In situ studies of the formation using ultrasmall angle X-ray scattering (USAXS) and small-angle X-ray scattering (SAXS) covering length scales from 5 to 10000 A, complemented with UV-vis and transmission electron microscopy (TEM), provide unique data on particle growth coupled with information regarding the progression of the mesostructure formation and the micellar evolution.

  • 34.
    Lundquist, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Wessman, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Physics.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Melittin–Lipid interaction: A comparative study using liposomes, micelles and bilayer disks2008In: Biochimica et Biophysica Acta - Biomembranes, ISSN 0005-2736, E-ISSN 1879-2642, Vol. 1778, no 10, p. 2210-2216Article in journal (Refereed)
    Abstract [en]

    Comparison of melittin interaction with liposomes, bilayer disks and micelles showed that melittin binding to lipid aggregates is largely dictated by the amount of highly curved areas in the aggregates. The PEG-stabilised bilayer disks were characterised by a combination of small angle neutron scattering, cryo-transmission electron microscopy and dynamic light scattering. Importantly, the theoretically foreseen partial segregation of the lipid components, important for maintaining the structure of the bilayer disk, was confirmed. Steady state fluorescence spectroscopy indicated that melittin mainly resides at the rim of the bilayer disks. Results of the present study help increase the understanding of the mechanisms behind, and the physico-chemical factors affecting, melittin–lipid interaction. We suggest that bilayer disks, due to their stable structure, constitute interesting vehicles for transport of peptides that have high propensity to associate with lipid surfaces of high curvature.

  • 35. McGillivray, D. J.
    et al.
    Thomas, R. K.
    Rennie, Adrian
    Department of Chemistry, King's College London.
    Penfold, J.
    Sivia, D. S.
    Ordered structures of dichain cationic surfactants at interfaces2003In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 19, no 19, p. 7719-7726Article in journal (Refereed)
  • 36.
    Moulin, M.
    et al.
    Inst Laue Langevin, 71 Ave Martyrs, F-38042 Grenoble 9, France;Keele Univ, Fac Nat Sci, Keele ST5 5BG, Staffs, England.
    Mossou, E.
    Inst Laue Langevin, 71 Ave Martyrs, F-38042 Grenoble 9, France;Keele Univ, Fac Nat Sci, Keele ST5 5BG, Staffs, England.
    Signor, L.
    Univ Grenoble Alpes, CNRS, CEA, IBS, F-38000 Grenoble, France.
    Kieffer-Jaquinod, S.
    Univ Grenoble Alpes, INSERM, CEA, BGE, F-38000 Grenoble, France.
    Kwaambwa, H. M.
    Namibia Univ Sci & Technol, Fac Hlth & Appl Sci, Private Bag 13388,13 Jackson Kaujeua St, Windhoek, Namibia.
    Nermark, F.
    Univ Botswana, Dept Chem, Private Bag UB00704, Gaborone, Botswana.
    Gutfreund, P.
    Inst Laue Langevin, 71 Ave Martyrs, F-38042 Grenoble 9, France.
    Mitchell, E. P.
    Keele Univ, Fac Nat Sci, Keele ST5 5BG, Staffs, England;European Synchrotron Radiat Facil, 71 Ave Martyrs, F-38043 Grenoble 9, France.
    Haertlein, M.
    Inst Laue Langevin, 71 Ave Martyrs, F-38042 Grenoble 9, France.
    Forsyth, V. T.
    Inst Laue Langevin, 71 Ave Martyrs, F-38042 Grenoble 9, France;Keele Univ, Fac Nat Sci, Keele ST5 5BG, Staffs, England.
    Rennie, Adrian Robert
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Towards a molecular understanding of the water purification properties of Moringa seed proteins2019In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 554, p. 296-304Article in journal (Refereed)
    Abstract [en]

    Seed extracts from Moringa oleifera are of wide interest for use in water purification where they can play an important role in flocculation; they also have potential as anti-microbial agents. Previous work has focused on the crude protein extract. Here we describe the detailed biophysical characterization of individual proteins from these seeds. The results provide new insights relating to the active compounds involved. One fraction, designated Mo-CBP3, has been characterized at a molecular level using a range of biochemical and biophysical techniques including liquid chromatography, X-ray diffraction, mass spectrometry, and neutron reflection. The interfacial behavior is of particular interest in considering water purification applications and interactions with both charged (e.g. silica) and uncharged (alumina) surfaces were studied. The reflection studies show that, in marked contrast to the crude extract, only a single layer of the purified Mo-CBP3 binds to a silica interface and that there is no binding to an alumina interface. These observations are consistent with the crystallographic structure of Mo-CBP3-4, which is one of the main isoforms of the Mo-CBP3 fraction. The results are put in context of previous studies of the properties of the crude extract. This work shows possible routes to development of separation processes that would be based on the specific properties of individual proteins.

  • 37.
    Moulin, Martine
    et al.
    Inst Laue Langevin, Grenoble, France; Keele Univ, Fac Nat Sci, Staffs, England.
    Strohmeier, Gernot A.
    Acib, Austrian Ctr Ind Biotechnol GmbH, Graz, Austria; Graz Univ Technol, Inst Organ Chem, NAWI Graz, Graz, Austria.
    Hirz, Melanie
    Graz Univ Technol, Inst Mol Biotechnol, BioTechMed Graz, NAWI Graz, Graz, Austria.
    Thompson, Katherine C.
    Univ London, Birkbeck Coll, Dept Biol Sci, London, England; Univ London, Birkbeck Coll, Inst Struct & Mol Biol, London, England.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Campbell, Richard A.
    Inst Laue Langevin, Grenoble, France.
    Pichler, Harald
    Acib, Austrian Ctr Ind Biotechnol GmbH, Graz, Austria; Graz Univ Technol, Inst Mol Biotechnol, BioTechMed Graz, NAWI Graz, Graz, Austria.
    Maric, Selma
    Malmö Univ, Fac Hlth & Soc, Biofilms Res Ctr Biointerfaces, Malmö, Sweden; Malmö Univ, Fac Hlth & Soc, Biomed Sci Dept, Malmö, Sweden.
    Forsyth, V. Trevor
    Inst Laue Langevin, Grenoble, France; Keele Univ, Fac Nat Sci, Staffs, England.
    Haertlein, Michael
    Inst Laue Langevin, Grenoble, France.
    Perdeuteration of cholesterol for neutron scattering applications using recombinant Pichia pastoris2018In: Chemistry and Physics of Lipids, ISSN 0009-3084, E-ISSN 1873-2941, Vol. 212, p. 80-87Article in journal (Refereed)
    Abstract [en]

    Deuteration of biomolecules has a major impact on both quality and scope of neutron scattering experiments. Cholesterol is a major component of mammalian cells, where it plays a critical role in membrane permeability, rigidity and dynamics, and contributes to specific membrane structures such as lipid rafts. Cholesterol is the main cargo in low and high-density lipoprotein complexes (i.e. LDL, HDL) and is directly implicated in several pathogenic conditions such as coronary artery disease which leads to 17 million deaths annually. Neutron scattering studies on membranes or lipid-protein complexes exploiting contrast variation have been limited by the lack of availability of fully deuterated biomolecules and especially perdeuterated cholesterol. The availability of perdeuterated cholesterol provides a unique way of probing the structural and dynamical properties of the lipoprotein complexes that underly many of these disease conditions. Here we describe a procedure for in vivo production of perdeuterated recombinant cholesterol in lipid-engineered Pichia pastoris using flask and fed-batch fermenter cultures in deuterated minimal medium. Perdeuteration of the purified cholesterol was verified by mass spectrometry and its use in a neutron scattering study was demonstrated by neutron reflectometry measurements using the FIGARO instrument at the ILL.

  • 38.
    Nouhi, Shirin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Hellsing, Maja S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Kapaklis, Vassilios
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Grazing-Incidence Small Angle Neutron Scattering from Structures below an Interface2017In: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 50, no 4, p. 1066-1074Article in journal (Refereed)
    Abstract [en]

    Changes of scattering are observed as the grazing angle of incidence of an incoming beam increases and probes different depths in samples. A model has been developed to describe the observed intensity in grazing incidence small angle neutron scattering (GISANS) experiments. This includes the significant effects of instrument resolution, the sample transmission, which depends on both absorption and scattering, as well as the sample structure. The calculations are tested with self-organised structures of two colloidal samples with different size particles that were measured on two different instruments. The model allows calculations for various instruments with defined resolution and can be used to design future improved experiments. The possibilities and limits of GISANS for different studies are discussed using the model calculations. 

  • 39.
    Nouhi, Shirin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Koutsioubas, Alexandros
    Kapaklis, Vassilios
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Distortion of surfactant lamellar phases induced by surface roughnessIn: Article in journal (Refereed)
    Abstract [en]

    Self-assembly is a characteristic property of soft matter and understanding the factors which assist or perturb this process is of a great importance in many biological and industrial processes.  Amphiphiles self-assemble and order into a variety of structures including well-ordered lamellar phases.  The present work uses neutron reflectometry to explore the effects of both interface roughness and temperature on the lamellar-phase structure of a non-ionic surfactant at a solid/liquid interface.  The structure of concentrated solutions of tetraethyleneglycol dodecyl ether has been compared against a smooth surface and one with a roughness of the order of the lamellar spacing.  The results showed that the surfactant forms a well-order and aligned structure at smooth surface that extends to a depth of micrometers from the interface.  Increasing the temperature of the sample and subsequent cooling helped the alignment and increased the number of oriented layers at the surface.  The same sample formed a significantly less aligned structure at a rough surface that did not align to same extent after heating.  The perturbation of the structure caused by thermal fluctuations was found to be much less than that imposed by a small surface roughness.

     

    Keywords

  • 40.
    Nouhi, Shirin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Kwaambwa, Habauka M.
    Namibia University of Science and Technology.
    Gutfreund, Philipp
    Institut Laue - Langevin, France.
    Rennie, A. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Comparative study of flocculation and adsorption behavior of Moringa peregrina and Moringa oleifera seed proteins for water treatmentIn: Article in journal (Refereed)
  • 41.
    Nouhi, Shirin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Pascuala, Marc
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Hellsing, Maja S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Kwaambwa, Habauka M.
    Namibia University of Science and Technology, Faculty of Health and Applied Sciences, Private Bag 13388, 13 Storch Street, Windhoek, Namibia.
    Skoda, Maximilian W. A.
    Rutherford Appleton Laboratory, Harwell, Didcot OX11 0QX, United Kingdom.
    Höök, Fredrik
    Department of Applied Physics, Chalmers University of Technology, Gothenburg, Sweden.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Sticking particles to solid surfaces using Moringa oleifera proteins as a glue2018In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 168, p. 68-75Article in journal (Refereed)
    Abstract [en]

    Experimental studies have been made to test the idea that seed proteins from Moringa oleifera which are novel, natural flocculating agents for many particles could be used to promote adhesion at planar interfaces and hence provide routes to useful nanostructures. The proteins bind irreversibly to silica interfaces. Surfaces that had been exposed to protein solutions and rinsed were then exposed to dispersions of sulfonated polystyrene latex. Atomic force microscopy was used to count particle density and identified that the sticking probability was close to 1. Measurements with a quartz crystal microbalance confirmed the adhesion and indicated that repeated exposures to solutions of Moringa seed protein and particles increased the coverage. Neutron reflectivity and scattering experiments indicate that particles bind as a monolayer. The various results show that the 2S albumin seed protein can be used to fix particles at interfaces and suggest routes for future developments in making active filters or improved interfaces for photonic devices.

  • 42. Nylander, Tommy
    et al.
    Campell, Richard
    Vandoolaeghe, Pauline
    Cárdenas, Marité
    Linse, Per
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Physics.
    Neutron Reflectometry to Investigate the Delivery of Lipids and DNA to Interfaces2008In: Biointerphases, ISSN 1559-4106, Vol. 3, no 2, p. FB64-FB82Article, review/survey (Refereed)
    Abstract [en]

    The application of scattering methods in the study of biological and biomedical problems is a field of research that is currently experiencing fast growth. In particular, neutron reflectometry (NR) is a technique that is becoming progressively more widespread, as indicated by the current commissioning of several new reflectometers worldwide. NR is valuable for the characterization of biomolecules at interfaces due to its capability to provide quantitative structural and compositional information on relevant molecular length scales. Recent years have seen an increasing number of applications of NR to problems related to drug and gene delivery. We start our review by summarizing the experimental methodology of the technique with reference to the description of biological liquid interfaces. Various methods for the interpretation of data are then discussed, including a new approach based on the lattice mean-field theory to help characterize stimulus-responsive surfaces relevant to drug delivery function. Recent progress in the subject area is reviewed in terms of NR studies relevant to the delivery of lipids and DNA to surfaces. Lastly, we discuss two case studies to exemplify practical features of NR that are exploited in combination with complementary techniques. The first case concerns the interactions of lipid-based cubic phase nanoparticles with model membranes (a drug delivery application), and the second case concerns DNA compaction at surfaces and in the bulk solution (a gene delivery application).

  • 43.
    Oleshkevych, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Zamani, Atieh
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Kotenko, Igor
    Voloshko, Svitlana
    Sidorenko, Sergey
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Thermally driven redistribution of phases and components in Cu/Sn thin films2012In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 535, p. 108-113Article in journal (Refereed)
    Abstract [en]

    Unusual features of phase transformations under the thermal treatment of the thin films system Cu (80 nm)-Sn (20 nm) have been studied using a range of physical methods. Processes of mass transfer in thin layers were studied and regimes of thermal treatment were chosen to compare the influence of different temperatures for a given time and the influence of annealing time at a fixed temperature. Presence of the intermetallic phase Cu6Sn5 in the as-deposited state and its transformation into Cu3Sn phase after annealing at temperature 373 K for different times has been identified by grazing incidence X-ray diffraction. Annealing at a temperature of 473 K, and higher, leads to the formation, unexpectedly, of the Cu4Sn phase. The concentration distribution of tin through the depth of the sample was obtained by Rutherford backscattering spectroscopy and demonstrated the existence of the Cu4Sn composition. The topography of the surface of the samples was determined with atomic-force microscopy.

  • 44.
    Oleskevych, Anna I
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Voloshko, S.M.
    Kyiv Polytechnic Institute.
    Sidorenko, S. I.
    Kyiv Polytechnic Institute.
    Langer, G. A.
    University of Debrecen.
    Beke, D. L.
    University of Debrecen.
    Rennie, Adrian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Enhanced diffusion caused by surface reactions in thin films of Sn–Cu–Mn2014In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 550, p. 723-731Article in journal (Refereed)
    Abstract [en]

    This paper describes an investigation of low-temperature diffusion in thin films of Sn/Cu, Cu/Mn and Sn/Cu/Mn. The combination of Rutherford backscattering spectroscopy, grazing incidence X-ray diffraction and Auger electron spectroscopy has been used to provide information about the concentration distribution of components and the depth of the various phases and interfaces. The results show that processes that occur on a free surface of thin films can stimulate diffusion of elements in the bulk. It is shown that the element with higher affinity to oxygen tends to move to the surface in order to oxidize and that this oxidation process provides a driving force for further diffusion. Introduction of a third layer to a bilayer system may lead to changes in the surface topography caused by the reactive diffusion between upper layers and it causes the development of fast, ‘short-circuit’ diffusion paths and so increases the diffusion of elements from the bottom to the top. Reactive diffusion between Sn and Cu in the top layers leads to significant changes at the surface with features of the size of 10 to 20 nmappearing. These changes provide shortcuts for the diffusion of Mn atoms from the bottom layer to the free surface. As a consequence of these processes, the sequence of layers of different elements in thin-film structures alters diffusionand results in different sample properties.

  • 45.
    Olsson, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Hellsing, Maja S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    A holder to rotate sample cells to avoid sedimentation in small-angle neutron scattering and ultra small-angle neutron scattering experiments2013In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 24, no 10, p. 105901-Article in journal (Refereed)
    Abstract [en]

    Sedimentation, or creaming, of samples can significantly alter the amount of material in the beam during small-angle scattering experiments. Simple rotating mounts that ameliorate this effect are described and the design criteria are carefully discussed. A modular design permits simple adaptation to various instruments and different sample cells. Temperature control in the range 10 degrees C below ambient to about +40 degrees C has been implemented using air flow and a Peltier device. Example ultra small-angle neutron scattering data are shown that exploit the simplicity of the mounts and the capability to position several samples close together on a translation stage.

  • 46.
    Olsson, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Hellsing, Maja S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    New possibilities using additive manufacturing with materials that are difficult to process and with complex structures2017In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 92, no 5, article id 053002Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing (or 3D printing) opens the possibility of creating new designs and manufacturing objects with new materials rapidly and economically. Particularly for use with polymers and polymer composites, simple printers can make high quality products, and these can be produced easily in offices, schools and in workshops and laboratories. This technology has opened a route for many to test ideas or to make custom devices. It is possible to easily manufacture complex geometries that would be difficult or even impossible to create with traditional methods. Naturally this technology has attracted attention in many fields that include the production of medical devices and prostheses, mechanical engineering as well as basic sciences. Materials that are highly problematic to machine can be used. We illustrate process developments with an account of the production of printer parts to cope with polymer fillers that are hard and abrasive; new nozzles with ruby inserts designed for such materials are durable and can be used to print boron carbide composites. As with other materials, complex parts can be printed using boron carbide composites with fine structures, such as screw threads and labels to identify materials. General ideas about design for this new era of manufacturing customised parts are presented.

  • 47.
    Olsson, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Rennie, Adrian R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. Uppsala Univ, Phys & Astron Mat Phys, S-75120 Uppsala, Sweden. Uppsala Univ, Ctr Neutron Scattering, S-75120 Uppsala, Sweden..
    Boron carbide composite apertures for small-angle neutron scattering made by three-dimensional printing2016In: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 49, no 2, p. 696-699Article in journal (Refereed)
    Abstract [en]

    Apertures for small-angle neutron scattering prepared from a boron carbide/polymer composite have been made by three-dimensional printing using fused filament fabrication. Use of enriched (B4C)-B-10 gives higher absorption and much lower parasitic scattering than natural B4C. The simple fabrication, the capability to replace toxic and environmentally hazardous materials such as cadmium, and the possibility to diminish the secondary background of gamma-radiation are attractive features of use of these materials. Complex shapes, apart from apertures, can be fabricated readily with this composite, for example, to make shielding for instrument components and masks used to calibrate detectors.

  • 48. Ottewill, R. H.
    et al.
    Rennie, Adrian
    Kings Coll London, Dept Chem, London.
    Johnson, G. D. W.
    Small-angle neutron scattering studies on binary mixtures of polystyrene and perfluorinated particles2003In: Advances in Colloid and Interface Science, ISSN 0001-8686, E-ISSN 1873-3727, Vol. 100-102, p. 585-611Article in journal (Refereed)
  • 49. Pontoni, D.
    et al.
    Finet, S.
    Narayanan, T.
    Rennie, Adrian
    Kings College London.
    Interactions and kinetic arrest in an adhesive hard-sphere colloidal system2003In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 119, no 12, p. 6157-6165Article in journal (Refereed)
  • 50. Pontoni, D.
    et al.
    Narayanan, T.
    Rennie, Adrian
    Kings College London.
    High-dynamic range SAXS data acquisition with an X-ray image intensifier2002In: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 35, p. 207-211Article in journal (Refereed)
12 1 - 50 of 82
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