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  • 51. Baev, A
    et al.
    Salek, Pawel
    KTH, Superseded Departments (pre-2005), Biotechnology.
    Gelmukhanov, Faris
    KTH, Superseded Departments (pre-2005), Biotechnology.
    Ågren, Hans
    KTH, Superseded Departments (pre-2005), Biotechnology.
    de Brito, N
    Bjorneholm, O
    Svensson, S
    Picturing molecular femtosecond processes through an ultra-fast controllable X-ray shutter2003In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 289, no 1, p. 51-56Article in journal (Refereed)
    Abstract [en]

    We show that frequency detuning in a resonant X-ray scattering experiment acts as an X-ray camera shutter by regulating the duration time of the scattering process. The camera shutter can be used to select processes at different time scales for observation. This is illustrated by a resonant Auger study of the ultra-fast dissociation of the core-excited HF molecule. We present experimental results and first principle simulations of the molecular fraction in the resonant Auger spectra of HF which is a dynamical parameter that well illustrates X-ray shutter controlled dissociation.

  • 52. Bahadur, Jitendra
    et al.
    Sen, Debasis
    Mazumder, S.
    Santoro, Gonzalo
    Yu, Shun
    Deutsches Elektronen-Synchrotron, Germany.
    Roth, S.V.
    Melnichenko, Yuri
    Evaporation Assisted Transition of Interaction Between Colloids: In-situ Small-angle X-ray Scattering Investigation2015In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, no 16, p. 4612-4618Article in journal (Refereed)
    Abstract [en]

    In-situ scanning small-angle X-ray scattering (SAXS) experiments have been performed to probe the,drying of a single suspended droplet of silica colloids. It has been demonstrated that the formation of a nanoparticle shell during drying can be confirmed just by measuring the temporal evolution of the spatial transmission profile across the drying droplet. The shrinkage of the droplet stops once the shell is formed. The temporal dependence Of the shell thickness and droplet radius has been estimated by quautitative analysis of the functionality of the transmission profiles. It is' revealed that the position of the correlation peak originating from interactions between silica nanoparticles evolves linearly during the initial stage of drying and exhibits sigmoidal growth behavior in later stages. The interaction between colloidal particles, in different drying stages has been investigated We provide,experimental confirmation of the transition from repulsive interaction to a capillary driven short-range,attraction,during shell formation. The present work demonstrates that in situ scanning SAXS on,a suspended droplet is an invaluable technique for monitoring the dynamic self organization of colloids as it probes the drying of complex,fluids without the interference of a substrate.

  • 53. Bain, C. D.
    et al.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Langevin, D.
    Meszaros, R.
    Nylander, T.
    Stubenrauch, C.
    Titmuss, S.
    von Klitzing, R.
    Complexes of surfactants with oppositely charged polymers at surfaces and in bulk2010In: Advances in Colloid and Interface Science, ISSN 0001-8686, E-ISSN 1873-3727, Vol. 155, no 1-2, p. 32-49Article in journal (Refereed)
    Abstract [en]

    Addition of surfactants to aqueous solutions of polyelectrolytes carrying an opposite charge causes the spontaneous formation of complexes in the bulk phase in certain concentration ranges. Under some conditions, compact monodisperse multichain complexes are obtained in the bulk. The size of these complexes depends on the mixing procedure and it can be varied in a controlled way from nanometers up to micrometers. The complexes exhibit microstructures analoguous to those of the precipitates formed at higher concentrations. In other cases, however, the bulk complexes are large, soft and polydisperse. In most cases, the dispersions are only kinetically stable and exhibit pronounced non-equilibrium features. Association at air-water interfaces readily occurs, even at very small concentrations. When the surfactant concentration is small, the surface complexes are usually made of a surfactant monolayer to which the polymer binds and adsorbs in a flat-like configuration. However, under some conditions, thicker layers can be found, with bulk complexes sticking to the surface. The association at solid-water interfaces is more complex and depends on the specific interactions between surfactants, polymers and the surface. However, the behaviour can be understood if distinctions between hydrophilic surfaces and hydrophobic surfaces are made. Note that the behaviour at air-water interfaces is closer to that of hydrophobic than that of hydrophilic solid surfaces. The relation between bulk and surface complexation will be discussed in this review. The emphasis will be given to the results obtained by the teams of the EC-funded Marie Curie RTN "SOCON".

  • 54.
    Bakyayita, Grace Kizito
    et al.
    KTH, School of Architecture and the Built Environment (ABE). Makerere University, Kyambogo University.
    Norrström, Ann-Catrine
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology. KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Kulabako, Robinah N.
    KTH, School of Architecture and the Built Environment (ABE). Department of Civil Engineering, CEDAT, Makerere University.
    Characterisation and application of untreated and base-treated biosorbents from Albizia coriaria, Erythrina abyssinica and Musa spp. in the uptake of Cd (II) and Pb (II) ions from contaminated waterManuscript (preprint) (Other academic)
    Abstract [en]

    The barks of Albizia coriaria, Erythrina abyssinica and peels of Musa spp. were studied in batch for removal of aqueous Cd2+ and Pb2+ ions at pH 4.5, agitation time 3.0 hours for 10 g/L biomass dosage. The biosorbents’ surfaces contained an array of heterogeneous sorption sites for metal ions. The trace metals in the biomass were in trace amounts.Results form XRD showed that organic species in the biosorbent surfaces were electron rich species expected to play part in the metal ions uptake. The biomass negative potential for binding base cations was in the order; Musa spp. > A. coriaria > E. abyssinica and base treatment reduced DOC leaching from the biosorbents in the order; E. abyssinica > A. coriaria > Musa spp. Speciation studies showed that more ions were complexed to DOC in solutions at various pH levels. The maximum sorption intensities for both Cd2+ and Pb2+ ions uptake onto biomass was highest for lowest initial metal concentration; 5 mg/L. Musa spp had the highest soprtion performance for both Cd2+ and Pb2+ ions. Freundlich model best fitted data for Pb2+ ions uptake whereas Temkin model fitted the sorption data for Cd2+ ions onto both treated and untreated biomass.

  • 55.
    Bakyayita, Grace Kizito
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. Makerere univ.
    Norrström, Ann-Catrine
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Kulabako, Robinah Nakawunde Akawunde
    Makerere univ.
    Competitive and Noncompetitive Batch Sorption Studies of Aqueous Cd(II) and Pb(II) Uptake onto Coffea canephora Husks, Cyperus papyrus Stems, and Musa spp. Peels2015In: Journal of Chemistry, ISSN 2090-9063, E-ISSN 2090-9071, article id 696098Article in journal (Refereed)
    Abstract [en]

    Coffea canephora, Cyperus papyrus, and Musa spp. were studied for competitive and noncompetitive removal of aqueous Cd2+ and Pb2+. The optimal conditions were pH 4.5 and agitation time 3.0 hours. Biomass constituent ions showed no interference effects whereas cation exchange capacity values corresponded to the sorption efficiencies. XRD spectroscopy revealed surface oxygen and nitrogen groups that provide binding sites for metal ions. The maximum sorption efficiency ranges for metal ions in noncompetitive media were 95.2-98.7% for C. canephora, 42.0-91.3% for C. papyrus, and 79.9-92.2% for Musa spp. and in competitive sorption 90.8-98.0% for C. canephora, 19.5-90.4% for C. papyrus, and 56.4-89.3% for Musa spp. The Pb2+ ions uptake was superior to that of Cd2+ ions in competitive and noncompetitive media. In competitive sorption synergistic effects were higher for Cd2+ than Pb2+ ions. The pseudo-second-order kinetic model fitted experimental data with 0.917 <= R-2 >= 1.000 for Pb2+ ions and 0.711 <= R-2 >= 0.999 for Cd2+ ions. The Langmuir model fitted noncompetitive sorption data with 0.769 <= R-2 >= 0.999; moreover the Freundlich model fitted competitive sorption data with 0.867 <= R-2 >= 0.989. Noncompetitive sorption was monolayer chemisorption whereas competitive sorption exhibited heterogeneous sorption mechanisms.

  • 56.
    Bao, Zhigang
    et al.
    Hong Kong Univ Sci & Technol, Hong Kong, Peoples R China..
    Erdos, Laszlo
    IST Austria, Klosterneuburg, Austria..
    Schnelli, Kevin
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematical Statistics.
    Equipartition principle for Wigner matrices2021In: Forum of Mathematics, Sigma, ISSN 2050-5094, Vol. 9, article id e44Article in journal (Refereed)
    Abstract [en]

    We prove that the energy of any eigenvector of a sum of several independent large Wigner matrices is equally distributed among these matrices with very high precision. This shows a particularly strong microcanonical form of the equipartition principle for quantum systems whose components are modelled by Wigner matrices.

  • 57.
    Barreiro, D.
    et al.
    Univ Autonoma Madrid, Dept Chem, Madrid 28049, Spain..
    Oostenrijk, B.
    Lund Univ, Dept Phys, S-22100 Lund, Sweden..
    Walsh, N.
    Lund Univ, Dept Phys, S-22100 Lund, Sweden..
    Sankari, A.
    Lund Univ, Dept Phys, S-22100 Lund, Sweden..
    Mansson, E. P.
    DESY, Attosecond Sci Grp, Photon Sci Div, Schenefeld, Germany..
    Maclot, Sylvain
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH Royal Inst Technol, Stockholm, Sweden..
    Sorensen, S.
    Lund Univ, Dept Phys, S-22100 Lund, Sweden..
    Diaz-Tendero, S.
    Univ Autonoma Madrid, Dept Chem, Madrid 28049, Spain.;Univ Autonoma Madrid, IFIMAC, Madrid 28049, Spain..
    Gisselbrecht, M.
    Lund Univ, Dept Phys, S-22100 Lund, Sweden..
    Deepening into the nucleation and fission processes of nano-hydrated ammonia clusters - a combined theoretical and experimental study2020In: 31ST INTERNATIONAL CONFERENCE ON PHOTONIC, ELECTRONIC AND ATOMIC COLLISIONS (ICPEAC XXXI) / [ed] Ancarani, LU Bordas, C Lepine, F Vernhet, D Bachau, H Bredy, R Dulieu, O Penent, F, IOP Publishing , 2020, article id 202030Conference paper (Refereed)
    Abstract [en]

    While largely studied in the macroscopic scale, the dynamics leading to the nucleation and fission of atmospheric aerosols are very poorly understood at the nano or molecular scale. A model system consisting on ionized hydrogen-bonded ammonia and water molecules have been studied experimentally using mass- and 3D momentum spectroscopy and theoretically using ab initio molecular dynamics simulations.

  • 58.
    Barreiro Fidalgo, Alexandre
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Experimental studies of radiation-induced dissolution of UO2: The effect of intrinsic solid phase properties and external factors2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dissolution of the UO2 matrix is one of the potential routes for radionuclide release in a future deep geological repository for spent nuclear fuel. This doctoral thesis focuses on interfacial reactions of relevance in radiation-induced dissolution of UO2 and is divided in two parts:

    In the first part, we sought to explore the effects of solid phase composition:

    The impact of surface stoichiometry on the reactivity of UO2 towards aqueous radiolytic oxidants was studied. H2O2 reacts substantially faster with stoichiometric UO2 than with hyperstoichiometric UO2. In addition, the release of uranium from stoichiometric UO2 is lower than from hyperstoichiometric UO2. The behavior of stoichiometric powder changes with exposure to H2O2, approaching the behavior of hyperstoichiometric UO2 with the number of consecutive H2O2 additions.

    The impact of Gd-doping on the oxidative dissolution of UO2 in an aqueous system was investigated. A significant decrease in uranium dissolution and higher stability towards H2O2 for (U,Gd)O2 pellets compared to standard UO2 was found.

    In the second part, we sought to look at the effect of external factors:

    The surface reactivity of H2 and O2 was studied to understand the overall oxide surface reactivity of aqueous molecular radiolysis products. The results showed that hydrogen-abstracting radicals and H2O2 are formed in these systems. Identical experiments performed in aqueous systems containing UO2 powder showed that the simultaneous presence of H2 and O2 enhances the oxidative dissolution of UO2 compared to a system not containing H2.

    The effect of groundwater components such as bentonite and sulfide on the oxidative dissolution of UO2 was also explored. The presence of bentonite and sulfide in water could either delay or prevent in part the release of uranium to the environment. The Pd catalyzed H2 effect is more powerful than the sulfide effect. The poisoning of Pd catalyst is not observed under the conditions studied.

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  • 59.
    Barreiro Fidalgo, Alexandre
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Radiation induced dissolution of (U, Gd)O2 pellets in aqueous solution: A comparison to standard UO2 pelletsManuscript (preprint) (Other academic)
    Abstract [en]

    In this work, the impact of burnable absorbers doping (Gd, 3-8%wt.) on the oxidative dissolution of UO2 in an aqueous system was studied by H2O2 and γ-irradiation induced dissolution experiments. The results showed a significant decrease in uranium dissolution and higher stability towards H2O2 for (U,Gd)O2 pellets compared to standard UO2. The resulting decrease in the final oxidative dissolution yield was mainly attributed to decreased redox reactivity of the UO2-matrix upon doping. During gamma radiation induced experiments, the difference in uranium release was even more pronounced compared to H2O2 induced dissolution experiments.

  • 60.
    Barreiro Fidalgo, Alexandre
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Kumagai, Yuta
    Japan Atomic Energy Agency.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Impact of stoichiometry on the reactivity of UO2 towards radiolytic oxidantsManuscript (preprint) (Other academic)
  • 61.
    Barreiro Fidalgo, Alexandre
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sundin, Sara
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Effect of bentonite on radiation induced dissolution of UO2 in an aqueous system2014In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 447, no 1-3, p. 73-76Article in journal (Refereed)
    Abstract [en]

    In order to elucidate the impact of bentonite on the process of radiation induced oxidative dissolution of UO2 in an aqueous system, the dissolution of U(VI) and consumption of H2O2 over time has been studied. In addition, γ-irradiation experiments were performed to study a more relevant and complex system, serving as a comparison with the previously stated system. In both cases, the experiments revealed that the presence of bentonite in water could either delay or prevent in part the release of uranium to the environment. The cause is mainly attributed to the scavenging of radiolytic oxidants rather than to the adsorption of uranium onto bentonite.

  • 62.
    Barrientos, Javier
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Lualdi, Matteo
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Suarez Paris, Rodrigo
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Montes, V.
    Boutonnet, Magali
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Järås, Sven
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    CO methanation over TiO2-supported nickel catalysts: A carbon formation study2015In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 502, p. 276-286Article in journal (Refereed)
    Abstract [en]

    A systematic study on titania-supported nickel catalysts was performed in order to evaluate the effect of different process conditions on catalyst stability. Reaction tests and temperature-programmed-hydrogenation analyses were used in order to evaluate the effect of temperature, feed composition, water and reduction conditions on catalyst deactivation and carbon deposition. It was shown that high H-2/CO ratios and syngas partial pressures decrease the rate of carbon formation. Moreover, increasing temperature enhanced the formation of more stable carbon species and thus catalyst deactivation. The temperature-programmed hydrogenation analyses also revealed that water reduces the rate of carbon deposition. However, water enhanced catalyst deactivation when the catalysts were reduced at high temperatures. This negative effect of water is probably due to a progressive destruction of the strong-metal-support interaction characteristic of titania-supported nickel catalysts reduced at high temperatures. (C) 2015 Elsevier B.V. All rights reserved.

  • 63. Bartenstein, J. E.
    et al.
    Liu, Xiaoyan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Lange, K.
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Briscoe, W. H.
    Polymersomes at the solid-liquid interface: Dynamic morphological transformation and lubrication2018In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 512, p. 260-271Article in journal (Refereed)
    Abstract [en]

    Polymersomes are hollow spheres self-assembled from amphiphilic block copolymers of certain molecular architecture. Whilst they have been widely studied for biomedical applications, relatively few studies have reported their interfacial properties. In particular, lubrication by polymersomes has not been previously reported. Here, interfacial properties of polymersomes self-assembled from poly(butadiene)-poly(ethylene oxide) (PBD-PEO; molecular weight 10,400 g mol−1) have been studied at both hydrophilic and hydrophobic surfaces. Their morphology at silica and mica surfaces was imaged with quantitative nanomechanical property mapping atomic force microscopy (QNM AFM), and friction and surface forces they mediate under confinement between two surfaces were studied using colloidal probe AFM (CP-AFM). We find that the polymersomes remained intact but adopted flattened conformation once adsorbed to mica, with a relatively low coverage. However, on silica these polymersomes were unstable, rupturing to form donut shaped residues or patchy bilayers. On a silica surface hydrophobized with a 19 nm polystyrene (PS) film, the polymer vesicles formed a more stable layer with a higher surface coverage as compared to the hydrophilic surface, and the interfacial structure also evolved over time. Moreover, friction was greatly reduced on hydrophobized silica surfaces in the presence of polymersomes, suggesting their potential as effective aqueous lubricants.

  • 64.
    Baryshnikov, Gleb V.
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Department of Organic Chemistry, Bohdan Khmelnitsky National University, Ukraine.
    Valiev, Rashid R.
    Karaush, Nataliya N.
    Sundholm, Dage
    Minaev, Boris F.
    Aromaticity of the doubly charged [8]circulenes2016In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 13, p. 8980-8992Article in journal (Refereed)
    Abstract [en]

    Magnetically induced current densities and current pathways have been calculated for a series of fully annelated dicationic and dianionic tetraphenylenes, which are also named [8]circulenes. The gauge including magnetically induced current (GIMIC) method has been employed for calculating the current density susceptibilities. The aromatic character and current pathways are deduced from the calculated current density susceptibilities showing that the neutral [8]circulenes have two concentric pathways with aromatic and antiaromatic character, respectively. The inner octatetraene core (the hub) is found to sustain a paratropic (antiaromatic) ring current, whereas the ring current along the outer part of the macrocycle (the rim) is diatropic (aromatic). The neutral [8]circulenes can be considered nonaromatic, because the sum of the ring-current strengths of the hub and the rim almost vanishes. The aromatic character of the doubly charged [8]circulenes is completely different: the dianionic [8]circulenes and the OC-, CH-, CH2-, SiH-, GeH-, SiH2-, and GeH2-containing dicationic species sustain net diatropic ring currents i.e., they are aromatic, whereas the O-, S-, Se-, NH-, PH- and AsH-containing dicationic [8]circulenes are strongly antiaromatic. The present study also shows that GIMIC calculations on the [8]circulenes provide more accurate information about the aromatic character than that obtained using local indices such as nuclear-independent chemical shifts (NICSs) and H-1 NMR chemical shifts.

  • 65.
    Bastardo Zambrano, Luis Alejandro
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Self assembly of surfactants and polyelectrolytes in solution and at interfaces2005Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This thesis focuses on the study of the interactions between polyelectrolytes and surfactants in aqueous solutions and at interfaces, as well as on the structural changes these molecules undergo due to that interaction. Small–angle neutron scattering, dynamic, and static light scattering were the main techniques used to investigate the interactions in bulk. The first type of polymer studied was a negatively charge glycoprotein (mucin); its interactions with ionic sodium alkyl sulfate surfactants and nonionic surfactants were determined. This system is of great relevance for several applications such as oral care and pharmaceutical products, since mucin is the main component of the mucus layer that protects the epithelial surfaces (e.g. oral tissues). Sodium dodecyl sulfate (SDS) on the other hand, has been used as foaming agent in tooth pastes for a very long time. In this work it is seen how SDS is very effective in dissolving the large aggregates mucin forms in solution, as well as in removing preadsorbed mucin layers from different surfaces. On the other hand, the nonionic surfactant n-dodecyl β-D-maltopyranoside (C12-mal), does not affect significantly the mucin aggregates in solution, neither does it remove mucin effectively from a negatively charge hydrophilic surface (silica). It can be suggested that nonionic surfactants (like the sugar–based C12-mal) could be used to obtain milder oral care products. The second type of systems consisted of positively charged polyelectrolytes and a negatively charged surfactant (SDS). These systems are relevant to a wide variety of applications ranging from mining and cleaning to gene delivery therapy. It was found that the interactions of these polyelectrolytes with SDS depend strongly on the polyelectrolyte structure, charge density and the solvent composition (pH, ionic strength, and so on). Large solvent isotopic effects were found in the interaction of polyethylene imine (PEI) and SDS, as well as on the interactions of this anionic surfactant and the sugar–based n-decyl β-D-glucopyranoside (C10G1). These surfactants mixtures formed similar structures in solutions to the ones formed by some of the polyelectrolytes studied, i.e. ellipsoidal micelles at low electrolyte concentration and stiff rods, at high electrolyte and SDS concentrations.

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  • 66.
    Bastardo Zambrano, Luis Alejandro
    et al.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Claesson, Per Martin
    KTH, Superseded Departments (pre-2005), Chemistry.
    Brown, W.
    Department of Physical Chemistry, University of Uppsala,.
    Interactions between mucin and alkyl sodium sulfates in solution: a light scattering study2002In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 18, no 10, p. 3848-3853Article in journal (Refereed)
    Abstract [en]

    The properties of negatively charged mucin in aqueous solutions and its interaction with anionic sodium alkyl sulfates with different hydrocarbon chain lengths were studied by means of dynamic light scattering. It was observed that mucin forms aggregates in aqueous solutions with a hydrodynamic radius above 500 nm. These aggregates dissolve when sodium dodecyl sulfate or sodium decyl sulfate is present at sufficiently high concentration, above about 0.2 cmc (critical micellar concentration). On the other hand, sodium octyl sulfate is not very effective in dissolving the mucin aggregates. The hydrodynamic radius of the dissolved mucin, decorated with some associated surfactant, is found to be in the range of 40-90 nm. The observation that the dissolving power of the sodium alkyl sulfates decreases with decreasing surfactant chain length suggests that the association between the surfactant and mucin is hydrophobically driven. The kinetics of the dissolution process depends on the surfactant concentration, a higher surfactant concentration giving rise to a more rapid dissolution of the aggregates. It was also observed that when the ionic strength is increased, the surfactant concentration needed to dissolve the mucin aggregates decreases. This can be explained by reduction of repulsive electrostatic forces by the salt.

  • 67.
    Bastardo Zambrano, Luis Alejandro
    et al.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Dedinaite, A.
    Unilever Res. Dvmt. Port Sunlight, Quarry Road East, Bebington, Wirral.
    Interactions between Mucin and Surfactants at Solid-Liquid Interfaces2002In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 18, no 24, p. 9383-9392Article in journal (Refereed)
    Abstract [en]

    The association between mucin and surfactants at the solid-liquid interface has been investigated employing reflectometry. The study is particularly aimed at understanding the removal of preadsorbed mucin layers by surfactant addition. To this end we investigated the effect of three different surfactants, one anionic surfactant, sodium dodecylsulfate (SDS), and two nonionic ones, penta(oxy ethylene) dodecyl ether (C12E5) and n-dodecyl beta-D-maltopyranoside (C-12-mal), All three surfactants were found to be potent in removing mucin from hydrophobic surfaces. On the otherhand, C-12-mal was found to have a very limited effect on mucin adsorbed to hydrophilic negatively charged surfaces, whereas the mucin layer was removed by SDS and C12E5. The association between mucin and the three different surfactants was also investigated by means of dynamic light scattering and surface tension measurements. It was concluded that SDS associates readily with mucin above a critical surfactant concentration, about 0.2 cmc, whereas the nonionic surfactants associate with mucin to a very limited degree. The results obtained with the different techniques allow us to propose that C12E5 removes mucin from silica surfaces by competitive adsorption, whereas the removal of mucin by SDS is due to formation of mucin/SDS complexes that have reduced surface affinity and increased water solubility compared to mucin alone.

  • 68.
    Bastardo Zambrano, Luis Alejandro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Garamus, V. M.
    GKSS Research Centre, Geesthacht.
    Bergström, Lars Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    The structures of complexes between polyethylene imine and sodium dodecyl sulfate in D2O: a scattering study2005In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, no 1, p. 167-174Article in journal (Refereed)
    Abstract [en]

    The association between a highly branched polyelectrolyte with ionizable groups, polyethylene imine (PEI), and an anionic surfactant, sodium dodecyl sulfate (SDS), has been investigated at two pH values, using small-angle neutron and light scattering. The scattering data allow us to obtain a detailed picture of the association structures formed. Small-angle neutron scattering (SANS) measurements in solutions containing highly charged PEI at low pH and low SDS concentrations indicate the presence of disklike aggregates. The aggregates change to a more complex three-dimensional structure with increasing surfactant concentration. One pronounced feature in the scattering curves is the presence of a Bragg-like peak at high q-values observed at a surfactant concentration of 4.2 mM and above. This scattering feature is attributed to the formation of a common well-ordered PEI/SDS structure, in analogue to what has been reported for other polyelectrolyte-surfactant systems. Precipitation occurred at the charge neutralization point, and X-ray diffraction measurements on the precipitate confirmed the existence of an ordered structure within the PEI/SDS aggregates, which was identified as a lamellar internal organization. Polyethylene imine has a low charge density in alkaline solutions. At pH 10.1 and under conditions where the surfactant was contrast matched, the SANS scattering curves showed only small changes with increasing surfactant concentration. This suggests that the polymer acts as a template onto which the surfactant molecules aggregate. Data from both static light scattering and SANS recorded under conditions where SDS and to a lower degree PEI contribute to the scattering were found to be consistent with a structure of stacked elliptic bilayers. These structures increased in size and became more compact as the surfactant concentration was increased up to the charge neutralization point.

  • 69.
    Bastardo Zambrano, Luis Alejandro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Iruthayaraj, Joseph
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Lundin, Maria
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Vareikis, Aušvydas
    Department of Polymer Chemistry, Vilnius University.
    Makuška, Ričardas
    Department of Polymer Chemistry, Vilnius University.
    van der Wal, Albert
    Lever Faberage Europe Global Technology Centre, Unilever R and D.
    Furó, István
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Garamus, Vasil M.
    GKSS Research Centre.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Soluble complexes in aqueous mixtures of low charge density comb polyelectrolyte and oppositely charged surfactant probed by scattering and NMR2007In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 312, no 1, p. 21-33Article in journal (Refereed)
    Abstract [en]

    A low charge density polyelectrolyte with a high graft density of 45 units long poly(ethylene oxide) side-chains has been synthesized. In this comb polymer, denoted PEO(45)MEMA:METAC-2, 2 mol% of the repeating methacrylate units in the polymer backbone carry a permanent positive charge and the remaining 98 mol% a 45 unit long PEO side-chain. Here we describe the solution conformation of this polymer and its association with an anionic surfactant, sodium dodecylsulfate, SDS. It will be shown that the polymer can be viewed as a stiff rod with a cross-section radius of gyration of 29 A. The cross section of the rod contracts with increasing temperature due to decreased solvency of the PEO side-chains. The anionic surfactant associates to a significant degree with PE045MEMA:METAC-2 to form soluble complexes at all stoichiometries. A cooperative association is observed as the free SDS concentration approaches 7 mM. At saturation the number of SDS molecules associated with the polymer amounts to 10 for each PEO side-chain. Two distinct populations of associated surfactants are observed, one is suggested to be molecularly distributed over the comb polymer and the other constitutes small micellar-like structures at the periphery of the aggregate. These conclusions are reached based on results from small-angle neutron scattering, static light scattering, NMR, and surface tension measurements.

  • 70.
    Bastardo Zambrano, Luis Alejandro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Mészaros, R.
    Department of Colloid Chemistry, Eötvös Loránd University, Budapest.
    Varga, I.
    Department of Colloid Chemistry, Eötvös Loránd University, Budapest.
    Gilanyi, T.
    Department of Colloid Chemistry, Eötvös Loránd University, Budapest.
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Deuterium isotope effects on the interaction between hyperbranched polyethylene imine and an anionic surfactant2005In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, no 33, p. 16196-16202Article in journal (Refereed)
    Abstract [en]

    Solvent isotope effects on the interaction between the hyperbranched cationic polyelectrolyte, polyethylene imine (PEI), and the anionic surfactant sodium dodecyl sulfate (SDS) were investigated using potentiometric titration and eletrophoretic mobility measurements. In the basic pH range, a significantly higher fraction of the amine groups was found to be protonated when the PEI was dissolved in D2O compared to H2O at the same pH/pD. The difference in polymer charge in the two solvents decreases gradually with decreasing pH, and it completely diminishes at around pH = 4. Electrophoretic mobility measurements of PEI/SDS complexes at different pH values correlated very well with these observations. At pH/pD approximate to 9 a much higher mobility of the PEI/SDS complexes was found in D2O than in H2O at low surfactant concentrations, and the charge neutralization point shifted to a considerably larger surfactant concentration in heavy water. These results can be explained by the significantly higher charge density of the PEI in D2O compared to H2O. However, at the natural pH/pD as well as at pH = 4 and pD = 4 conditions the PEI molecules have roughly equal charge densities, which result in very similar charged characteristics (mobilities) of the PEI/SDS complexes as well as the same charge neutralization SDS concentration. It can be concluded that extreme care must be taken in the general analysis of those experiments in which weak polyelectrolyte/surfactant aggregates are investigated in heavy water, and then these observations are correlated with structures of the same system in water.

  • 71.
    Batalovic, K.
    et al.
    Univ Belgrade, Natl Inst Republ Serbia, VINCA Inst Nucl Sci, Belgrade, Serbia.;Ctr Excellence Hydrogen & Renewable Energy CONVIN, POB 522, Belgrade 11001, Serbia..
    Radakovic, J.
    Univ Belgrade, Natl Inst Republ Serbia, VINCA Inst Nucl Sci, Belgrade, Serbia.;Ctr Excellence Hydrogen & Renewable Energy CONVIN, POB 522, Belgrade 11001, Serbia..
    Bundaleski, N.
    Univ Belgrade, Natl Inst Republ Serbia, VINCA Inst Nucl Sci, Belgrade, Serbia.;Nova Univ Lisbon, Sch Sci & Technol, Ctr Phys & Technol Res, P-2829516 Caparica, Portugal..
    Rakocevic, Z.
    Univ Belgrade, Natl Inst Republ Serbia, VINCA Inst Nucl Sci, Belgrade, Serbia..
    Pasti, I
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia..
    Skorodumova, Natalia
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Structures. Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala, 751 20, Sweden.
    Rangel, C. M.
    Natl Lab Energy & Geol, LNEG, Paco do Lumiar 22, P-1649038 Lisbon, Portugal..
    Origin of photocatalytic activity enhancement in Pd/Pt-deposited anatase N-TiO2- experimental insights and DFT study of the (001) surface2020In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 22, no 33, p. 18536-18547Article in journal (Refereed)
    Abstract [en]

    In pursuit of the ideal photocatalyst, cheap and stable semiconductor TiO(2)is considered to be a good choice if one is able to reduce its band gap and decrease the recombination rate of charge carriers. The approach that offers such improvements for energy conversion applications is the modification of TiO(2)with nitrogen and noble metals. However, the origin of these improvements and possibilities for further design of single-atom catalysts are not always straightforward. To shed light on the atomic-scale picture, we modeled the nitrogen-doped (001) anatase TiO(2)surface as a support for palladium and platinum single-atom deposition. The thermodynamics of various synthesis routes for Pd/Pt deposition and nitrogen doping is considered based on density functional theory (DFT)-calculated energies, highlighting the effect of nitrogen doping on metal dimer formation and metal-support interaction. XPS analysis of the valence band of the modified TiO(2)nanocrystals, and the calculated charge transfer and electronic structure of single-atom catalysts supported on the (001) anatase TiO(2)surface provide an insight into modifications occurring in the valence zone of TiO(2)due to nitrogen doping and Pd/Pt deposition at the surface. DFT results also show that substitutional nitrogen doping significantly increases metal-support interaction, while interstitial nitrogen doping promotes only Pt-support interaction.

  • 72.
    Batili, Hazal
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hamawandi, Bejan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Ergül, Adem Björn
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Szukiewicz, Rafal
    Institute of Experimental Physics, University of Wroclaw, Maxa Borna 9, 50–204 Wroclaw, Poland, Maxa Borna 9.
    Kuchowicz, Maciej
    Institute of Experimental Physics, University of Wroclaw, Maxa Borna 9, 50–204 Wroclaw, Poland, Maxa Borna 9.
    Toprak, Muhammet
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    A comparative study on the surface chemistry and electronic transport properties of Bi2Te3 synthesized through hydrothermal and thermolysis routes2024In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, E-ISSN 1873-4359, Vol. 682, article id 132898Article in journal (Refereed)
    Abstract [en]

    Bismuth telluride-Bi2Te3 is the most promising material for harvesting thermal energy near room temperature. There are numerous works on Bi2Te3 reporting significantly different transport properties, with no clear connection to the synthetic routes used and the resultant surface chemistry of the synthesized materials. It is of utmost importance to characterize the constituent particles’ surface and interfaces to get a better understanding of their influence on the transport properties, that will significantly improve the material design starting from the synthesis step. Electrophoretic deposition (EPD) is a promising technique, enabling the formation of thick films using colloidally stabilized suspensions of pre-made nanoparticles, which can enable the study of the effect of surface chemistry, in connection to the synthetic route, on the material's transport properties. In order to explore the differences in surface chemistry and the resultant transport properties in relation to the synthetic scheme used, here we report on Bi2Te3 synthesised through two wet-chemical routes in water (Hydro-) and oil (Thermo-) as the solvents. XRD analysis showed a high phase purity of the synthesized materials. SEM analysis revealed hexagonal platelet morphology of the synthesized materials, which were then used to fabricate EPD films. Characterization of the EPD films reveal significant differences between the Hydro- and Thermo-Bi2Te3 samples, leading to about 8 times better electrical conductivity values in the Thermo-Bi2Te3. XPS analysis revealed a higher metal oxides content in the Hydro-Bi2Te3 sample, contributing to the formation of a resistive layer, thus lowering the electrical conductivity. Arrhenius plots of electrical conductivity vs inverse temperature was used for the estimation of the activation energy for conduction, revealing a higher activation energy need for the Hydro-Bi2Te3 film, in agreement with the resistive barrier oxide content. Both the samples exhibited negative Seebeck coefficient (S) in the order of 160–170 mV/K. The small difference in S of Hydro- and Themo-Bi2Te3 films was explained by the effective medium theory, revealing that the magnitude of S is linearly correlated with the surface oxide content. Based on the findings, TE materials synthesized through thermolysis route is recommended for further studies using soft treatment/processing of pre-made TE materials. EPD platform presented here is shown to clearly expose the differences in the electronic transport in connection to nanoparticle surface chemistry, proving a promising methodology for the evaluation of morphology, size and surface chemistry dependence of electronic transport for a wide range of materials.

  • 73. Bavinck, Maaike Bouwes
    et al.
    Jons, Klaus D.
    Zielinski, Michal
    Patriarche, Gilles
    Harmand, Jean-Christophe
    Akopian, Nika
    Zwiller, Val
    KTH, School of Engineering Sciences (SCI), Applied Physics. Delft Univ Techno, Netherlands.
    Photon Cascade from a Single Crystal Phase Nanowire Quantum Dot2016In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 16, no 2, p. 1081-1085Article in journal (Refereed)
    Abstract [en]

    We report the first comprehensive experimental and theoretical study of the optical properties of single crystal phase quantum dots in InP nanowires. Crystal phase quantum dots are defined by a transition in the crystallographic lattice between zinc blende and wurtzite segments and therefore offer unprecedented potential to be controlled with atomic layer accuracy without random alloying. We show for the first time that crystal phase quantum dots are a source of pure single-photons and cascaded photon-pairs from type II transitions with excellent optical properties in terms of intensity and line width. We notice that the emission spectra consist often of two peaks close in energy, which we explain with a comprehensive theory showing that the symmetry of the system plays a crucial role for the hole levels forming hybridized orbitals. Our results state that crystal phase quantum dots have promising quantum optical properties for single photon application and quantum optics.

  • 74.
    Baykov, Vitaly
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Isaev, P. A.
    Moscow State Institute of Steel and Alloys.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Vekilov, Y. K.
    Moscow State Institute of Steel and Alloys.
    Abrikosov, I. A.
    Linköping University.
    Ab Initio Studies of the Energy Characteristics and Magnetic Properties of Point Defects in GaAs2005In: Physics of the solid state, ISSN 1063-7834, E-ISSN 1090-6460, Vol. 47, no 10, p. 1831-1836Article in journal (Refereed)
    Abstract [en]

    The formation energies of intrinsic point defects and solution energies of transition metal impurities in gallium arsenide are determined on the basis of ab initio calculations using the method of a locally self-consistent Green's function, which is a generalization of the coherent potential approximation. Based on the calculated energies, the conclusion is made that the As-Ga antisite defect is the most common intrinsic defect in GaAs. Calculations showed that transition metal impurities, except for Ni, preferentially occupy gallium sites substitutionally. The magnetic moments of impurity atoms are calculated as a function of the chemical environment. It is shown that, in compensated GaAs, Mn atoms tend to form clusters.

  • 75.
    Baykov, Vitaly
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Diffusion of Interstitial Mn in the Dilute Magnetic Semiconductor (Ga,Mn)As: The Effect of a Charge State2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 17, p. 177204-Article in journal (Refereed)
    Abstract [en]

    Migration barriers for diffusion of interstitial Mn in the dilute magnetic semiconductor (Ga,Mn)As are studied using first-principles calculations. The diffusion pathway goes through two types of interstitial sites: As coordinated and Ga coordinated. The energy profile along the path is found to depend on the ratio of concentrations between substitutional and interstitial Mn in GaAs. Two regions of distinctly different behavior, corresponding to n-type and p-type (Ga,Mn)As, are identified. The difference in mobility is a reflection of the change in the charge state of Mn interstitials (double donors) that occurs in the presence of substitutional Mn impurities (acceptors). In addition, substitutional Mn impurities are shown to act as traps for interstitial Mn. The effective migration barrier for the positively doubly charged Mn interstitials in p-type (Ga,Mn)As is estimated to vary from 0.55 to about 0.95 eV.

  • 76.
    Baykov, Vitaly
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Smirnova, E. A.
    Department of Theoretical Physics of Steel and Alloys, Moscow.
    Abrikosov, I. A.
    Department of Physics and Measurement Technology, Linköping University.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Magnetic properties of 3d impurities in GaAs2007In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 310, no 2, p. 2120-2122Article in journal (Refereed)
    Abstract [en]

    Electronic structure, thermodynamic, and magnetic properties of 3d-transition metal (TM) impurities in GaAs have been studied from first principles using Green's function approach. The studied TM impurities (V, Cr, Mn, and Fe) are found to form substitutional alloys on the Ga sublattice. The possibility of raising the Curie temperature TC in (GaMn) As by co-doping it with Cr impurities was examined on the basis of total energy difference between the disordered local moment (DLM) and the ferromagnetically ordered (FM) spin configurations. The calculated Curie temperature and magnetic moment have maxima for GaAs doped with Cr and Mn. The magnetic properties of Mn-doped GaAs are shown to be more sensitive to antisite As defects than those of Cr-doped GaAs. However, the Cr impurities are sensitive to the presence of acceptor defects, such as vacancies on the Ga sublattice. The investigation of the electronic structure of pseudo-ternary alloys (Ga(1-x-y)MnxCry) As has shown a mutual compensation of Mn and Cr impurities. Therefore, in order to reach the highest critical temperature, GaAs has to be separately doped with Cr or Mn impurities. The GaAs doped with Fe is found to be non-ferromagnetic.

  • 77.
    Bazesefidpar, Kazem
    et al.
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Brandt, Luca
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. Norwegian Univ Sci & Technol NTNU, Dept Energy & Proc Engn, Trondheim, Norway..
    Tammisola, Outi
    KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Numerical simulation of the coalescence-induced polymeric droplet jumping on superhydrophobic surfaces2022In: Journal of Non-Newtonian Fluid Mechanics, ISSN 0377-0257, E-ISSN 1873-2631, Vol. 307, article id 104872Article in journal (Refereed)
    Abstract [en]

    Self-propelled jumping of two polymeric droplets on superhydrophobic surfaces is investigated by three-dimensional direct numerical simulations. Two identical droplets of a viscoelastic fluid slide, meet and coalesce on a surface with contact angle 180 degrees. The droplets are modelled by the Giesekus constitutive equation, introducing both viscoelasticity and a shear-thinning effects. The Cahn-Hilliard Phase-Field method is used to capture the droplet interface. The simulations capture the spontaneous coalescence and jumping of the droplets. The effect of elasticity and shear-thinning on the coalescence and jumping is investigated at capillary-inertial and viscous regimes. The results reveal that the elasticity of the droplet changes the known capillary-inertial velocity scaling of the Newtonian drops at large Ohnesorge numbers; the resulting viscoelastic droplet jumps from the surface at larger Ohnesorge numbers than a Newtonian drop, when elasticity amplifies visible shape oscillations of the merged droplet. The numerical results show that polymer chains are stretched during the coalescence and prior to the departure of two drops, and the resulting elastic stresses at the interface induce the jumping of the liquid out of the surface. This study shows that viscoelasticity, typical of many biological and industrial applications, affects the droplet behaviour on superhydrophobic and self-cleaning surfaces.

  • 78. Bednarska, Joanna
    et al.
    Zalesny, Robert
    Wielgus, Malgorzata
    Jedrzejewska, Beata
    Puttreddy, Rakesh
    Rissanen, Kari
    Bartkowiak, Wojciech
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Osmialowski, Borys
    Two-photon absorption of BF2-carrying compounds: insights from theory and experiment2017In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 8, p. 5705-5708Article in journal (Refereed)
    Abstract [en]

    This communication presents a structure-property study of a few novel pyridine-based difluoroborate compounds with a N-BF2-O core, which exhibit outstanding fluorescence properties. To exploit their potential for two-photon bioimaging, relationships between the two-photon action cross section and systematic structural modifications have been investigated and unravelled.

  • 79.
    Behroozi Kohlan, Taha
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology. Sabanci Univ, Integrated Mfg Technol Res & Applicat Ctr, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Composite Technol Ctr Excellence, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Fac Engn & Nat Sci, Mat Sci & Nano Engn, TR-34956 Istanbul, Turkiye.
    Atespare, Asu Ece
    Sabanci Univ, Integrated Mfg Technol Res & Applicat Ctr, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Composite Technol Ctr Excellence, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Fac Engn & Nat Sci, Mat Sci & Nano Engn, TR-34956 Istanbul, Turkiye..
    Yildiz, Mehmet
    Sabanci Univ, Integrated Mfg Technol Res & Applicat Ctr, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Composite Technol Ctr Excellence, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Fac Engn & Nat Sci, Mat Sci & Nano Engn, TR-34956 Istanbul, Turkiye..
    Menceloglu, Yusuf Ziya
    Sabanci Univ, Integrated Mfg Technol Res & Applicat Ctr, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Composite Technol Ctr Excellence, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Fac Engn & Nat Sci, Mat Sci & Nano Engn, TR-34956 Istanbul, Turkiye..
    Unal, Serkan
    Sabanci Univ, Integrated Mfg Technol Res & Applicat Ctr, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Composite Technol Ctr Excellence, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Fac Engn & Nat Sci, Mat Sci & Nano Engn, TR-34956 Istanbul, Turkiye..
    Dizman, Bekir
    Sabanci Univ, Integrated Mfg Technol Res & Applicat Ctr, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Composite Technol Ctr Excellence, TR-34956 Istanbul, Turkiye.;Sabanci Univ, Fac Engn & Nat Sci, Mat Sci & Nano Engn, TR-34956 Istanbul, Turkiye..
    Amphiphilic Polyoxazoline Copolymer-Imidazole Complexes as Tailorable Thermal Latent Curing Agents for One-Component Epoxy Resins2023In: ACS Omega, E-ISSN 2470-1343, Vol. 8, no 49, p. 47173-47186Article in journal (Refereed)
    Abstract [en]

    One-component epoxy resins (OCERs) are proposed to overcome the energy inefficiency and processing difficulties of conventional two-component epoxy resins by employing latent curing agents, specifically thermal latent curing agents (TLCs). Despite recent progress, the need for TLCs with a simple preparation method for different curing agents, epoxy resins, and process conditions remains. Here, tailorable TLCs were prepared by forming complexes between imidazole (Im) and amphiphilic polyoxazoline copolymers with tunable structures and properties by a solvent evaporation method. The obtained TLCs were manually mixed with DGEBA to prepare OCERs. The miscibility of the complexes with DGEBA was studied, considering the functionalities of copolymers. The curing behaviors of TLCs were compared using dynamic Differential Scanning Calorimetry (DSC) studies considering the side chain and composition of the copolymers, copolymer:Im ratio, and concentration of Im in DGEBA. The curing behavior of the promising OCERs was studied by isothermal DSC studies to investigate their stability at different temperatures and curing rate at elevated temperatures revealing the stability of these OCERs.

  • 80.
    Beldowski, Piotr
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Engineering Pedagogics. Bydgoszcz Univ Sci & Technol, Inst Math & Phys, Fac Chem Technol & Engn, PL-85796 Bydgoszcz, Poland..
    Przybylek, Maciej
    Nicolaus Copernicus Univ Torun, Coll Med Bydgoszcz, Pharm Fac, Dept Phys Chem, Kurpinskiego 5, PL-85950 Bydgoszcz, Poland..
    Raczynski, Przemyslaw
    Univ Silesia Katowice, Fac Sci & Technol, 75 Pulku Piechoty 1A, PL-41500 Chorzow, Poland..
    Dédinaité, Andra
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Res Inst Sweden, Div Biosci & Mat, SE-11486 Stockholm, Sweden..
    Gorny, Krzysztof
    Univ Silesia Katowice, Fac Sci & Technol, 75 Pulku Piechoty 1A, PL-41500 Chorzow, Poland..
    Wieland, Florian
    Helmholtz Zentrum Hereon, Inst metall Biomat, Max Planck Str 1, D-21502 Geesthacht, Germany..
    Dendzik, Zbigniew
    Univ Silesia Katowice, Fac Sci & Technol, 75 Pulku Piechoty 1A, PL-41500 Chorzow, Poland..
    Sionkowska, Alina
    Nicolaus Copernicus Univ Torun, Fac Chem, Dept Biomat & Cosmet Chem, Gagarin 7, PL-87100 Torun, Poland..
    Claesson, Per M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Albumin-Hyaluronan Interactions: Influence of Ionic Composition Probed by Molecular Dynamics2021In: International Journal of Molecular Sciences, ISSN 1661-6596, E-ISSN 1422-0067, Vol. 22, no 22, article id 12360Article in journal (Refereed)
    Abstract [en]

    The lubrication mechanism in synovial fluid and joints is not yet fully understood. Nevertheless, intermolecular interactions between various neutral and ionic species including large macromolecular systems and simple inorganic ions are the key to understanding the excellent lubrication performance. An important tool for characterizing the intermolecular forces and their structural consequences is molecular dynamics. Albumin is one of the major components in synovial fluid. Its electrostatic properties, including the ability to form molecular complexes, are closely related to pH, solvation, and the presence of ions. In the context of synovial fluid, it is relevant to describe the possible interactions between albumin and hyaluronate, taking into account solution composition effects. In this study, the influence of Na+, Mg2+, and Ca2+ ions on human serum albumin-hyaluronan interactions were examined using molecular dynamics tools. It was established that the presence of divalent cations, and especially Ca2+, contributes mostly to the increase of the affinity between hyaluronan and albumin, which is associated with charge compensation in negatively charged hyaluronan and albumin. Furthermore, the most probable binding sites were structurally and energetically characterized. The indicated moieties exhibit a locally positive charge which enables hyaluronate binding (direct and water mediated).

  • 81.
    Belonoshko, Anatoly
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Condensed Matter Theory.
    Fu, Jie
    Ningbo Univ, Dept Phys, Fac Sci, Ningbo 315211, Zhejiang, Peoples R China..
    Bryk, Taras
    Natl Acad Sci Ukraine, Inst Condensed Matter Phys, UA-79011 Lvov, Ukraine..
    Simak, Sergei, I
    Linkoping Univ, Dept Phys Chem & Biol IFM, SE-58183 Linkoping, Sweden..
    Mattesini, Maurizio
    Univ Complutense Madrid, Dept Earths Phys & Astrophys, E-28040 Madrid, Spain.;UCM, CSIC, Fac Ciencias Fis, Inst Geociencias, Plaza Ciencias 1, Madrid 28040, Spain..
    Low viscosity of the Earth's inner core2019In: Nature Communications, E-ISSN 2041-1723, Vol. 10, article id 2483Article in journal (Refereed)
    Abstract [en]

    The Earth's solid inner core is a highly attenuating medium. It consists mainly of iron. The high attenuation of sound wave propagation in the inner core is at odds with the widely accepted paradigm of hexagonal close-packed phase stability under inner core conditions, because sound waves propagate through the hexagonal iron without energy dissipation. Here we show by first-principles molecular dynamics that the body-centered cubic phase of iron, recently demonstrated to be thermodynamically stable under the inner core conditions, is considerably less elastic than the hexagonal phase. Being a crystalline phase, the body-centered cubic phase of iron possesses the viscosity close to that of a liquid iron. The high attenuation of sound in the inner core is due to the unique diffusion characteristic of the body-centered cubic phase. The low viscosity of iron in the inner core enables the convection and resolves a number of controversies.

  • 82. Bencsik, G.
    et al.
    Janáky, C.
    Kriván, E.
    Lukács, Z.
    Endrődi, Balázs
    Visy, C.
    Conducting polymer based multifunctional composite electrodes2009In: Reaction Kinetics and Catalysis Letters, Vol. 96, p. 421-428Article in journal (Refereed)
    Abstract [en]

    In this paper, we report a novel pattern of composite electrocatalysts. PPy/iron-oxalate films exhibit photo-electrochemical activity. The PPy/B12 composite electrode on stainless steal (SS) support shows high catalytic activity in the electrochemical reduction of methylviologen. Thin polymer layers filled with magnetite particles can be applicable in magneto-selective electrochemical reactions.

    In this paper, we report a novel pattern of composite electrocatalysts. PPy/iron-oxalate films exhibit photo-electrochemical activity. The PPy/B12 composite electrode on stainless steal (SS) support shows high catalytic activity in the electrochemical reduction of methylviologen. Thin polymer layers filled with magnetite particles can be applicable in magneto-selective electrochemical reactions.

  • 83. Bencsik, Gábor
    et al.
    Janáky, Csaba
    Endrődi, Balázs
    University of Szeged, Hungary.
    Visy, Csaba
    Electrocatalytic properties of the polypyrrole/magnetite hybrid modified electrode towards the reduction of hydrogen peroxide in the presence of dissolved oxygen2012In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 73, p. 53-58Article in journal (Refereed)
    Abstract [en]

    In this study, we report on the electrocatalytic behaviour of a polypyrrole/magnetite hybrid electrode towards the reduction of hydrogen peroxide. The electrocatalytic activity of the composite electrode was demonstrated by cyclic voltammetric and chrono-amperometric measurements in comparison with the identically prepared neat polymer film. The stationary reduction currents, measured at an appropriately chosen potential (here at E = -0.3 V), plotted against the peroxide concentration gave a perfect linear correlation in nitrogen atmosphere in the micromolar concentration range. The performance of the composite electrode was not affected by the presence of sulphate, nitrate or chloride anions. In the presence of dissolved oxygen a complex electrocatalytic activity was observed, involving the reduction of both oxygen and H2O2. However, a linear dependence was found also in oxygen containing media, although with much higher currents, but with the same slope (even at different oxygen concentrations). This fact may trigger the development of such hybrid electrodes towards hydrogen peroxide sensors in different aqueous (including natural) samples.

  • 84.
    Benselfelt, Tobias
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Design of Cellulose-based Materials by Supramolecular Assemblies2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Due to climate change and plastic pollution, there is an increasing demand for bio-based materials with similar properties to those of common plastics yet biodegradable. In this respect, cellulose is a strong candidate that is already being refined on a large industrial scale, but the properties differ significantly from those of common plastics in terms of shapeability and water-resilience.

    This thesis investigates how supramolecular interactions can be used to tailor the properties of cellulose-based materials by modifying cellulose surfaces or control the assembly of cellulose nanofibrils (CNFs). Most of the work is a fundamental study on interactions in aqueous environments, but some material concepts are presented and potential applications are discussed.

    The first part deals with the modification of cellulose by the spontaneous adsorption of xyloglucan or polyelectrolytes. The results indicate that xyloglucan adsorbs to cellulose due to the increased entropy of water released from the surfaces, which is similar to the increased entropy of released counter-ions that drives polyelectrolyte adsorption. The polyelectrolyte adsorption depends on the charge of the cellulose up to a limit after which the charge density affects only the first adsorbed layer in a multilayer formation.

    Latex nanoparticles with polyelectrolyte coronas can be adsorbed onto cellulose in order to prepare hydrophobic cellulose surfaces with strong and ductile wet adhesion, provided the glass transition of the core is below the ambient temperature.

    The second part of the thesis seeks to explain the interactions between different types of cellulose nanofibrils in the presence of different ions, using a model consisting of ion-ion correlation and specific ion effects, which can be employed to rationally design water-resilient and transparent nanocellulose films. The addition of small amounts of alginate also creates interpenetrating double networks, and these networks lead to a synergy which improves both the stiffness and the ductility of the films in water.

    A network model has been developed to understand these materials, with the aim to explain the properties of fibril networks, based on parameters such as the aspect ratio of the fibrils, the solidity of the network, and the ion-induced interactions that increase the friction between fibrils. With the help of this network model and the model for ion-induced interactions, we have created films with wet-strengths surpassing those of common plastics, or a ductility suitable for hygroplastic forming into water-resilient and biodegradable packages. Due to their transparency, water content, and the biocompatibility of cellulose, these materials are also suitable for biomaterial or bioelectronics applications. 

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  • 85.
    Benselfelt, Tobias
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Cranston, Emily D.
    Department of Chemical Engineering, McMaster University.
    Ondaral, Sedat
    Department of Pulp and Paper Technology, Karadeniz Technical University.
    Johansson, Erik
    Cellutech AB.
    Brumer, Harry
    The Michael Smith Laboratories and the Department of Chemistry, The University of British Columbia.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Adsorption of Xyloglucan onto Cellulose Surfaces of Different Morphologies: An Entropy-Driven Process2016In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 17, no 9, p. 2801-2811Article in journal (Refereed)
    Abstract [en]

    The temperature-dependence of xyloglucan (XG) adsorption onto smooth cellulose model films regenerated from N-methylmorpholine N-oxide (NMMO) was investigated using surface plasmon resonance spectroscopy, and it was found that the adsorbed amount increased with increasing temperature. This implies that the adsorption of XG to NMMO-regenerated cellulose is endothermic and supports the hypothesis that the adsorption of XG onto cellulose is an entropy-driven process. We suggest that XG adsorption is mainly driven by the release of water molecules from the highly hydrated cellulose surfaces and from the XG molecules, rather than through hydrogen bonding and van der Waals forces as previously suggested. To test this hypothesis, the adsorption of XG onto cellulose was studied using cellulose films with different morphologies prepared from cellulose nanocrystals (CNC), semicrystalline NMMO-regenerated cellulose, and amorphous cellulose regenerated from lithium chloride/dimethylacetamide. The total amount of high molecular weight xyloglucan (XGHMW) adsorbed was studied by quartz crystal microbalance and reflectometry measurements, and it was found that the adsorption was greatest on the amorphous cellulose followed by the CNC and NMMO-regenerated cellulose films. There was a significant correlation between the cellulose dry film thickness and the adsorbed XG amount, indicating that XG penetrated into the films. There was also a correlation between the swelling of the films and the adsorbed amounts and conformation of XG, which further strengthened the conclusion that the water content and the subsequent release of the water upon adsorption are important components of the adsorption process.

  • 86.
    Benselfelt, Tobias
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Nordenström, Malin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lindström, Stefan
    Linköping University.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Explaining the exceptional wet integrity of transparent cellulose nanofibril films in the presence of multivalent ions - Suitable substrates for biointerfacesManuscript (preprint) (Other academic)
  • 87.
    Benselfelt, Tobias
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Influence of Surface Charge Density and Morphology on the Formation of Polyelectrolyte Multilayers on Smooth Charged Cellulose Surfaces2017In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 33, no 4, p. 968-979Article in journal (Refereed)
    Abstract [en]

    To clarify the importance of the surface charge for the formation of polyelectrolyte multilayers, layer-by-layer (LbL) assemblies of polydiallyldimethylammonium chloride (pDADMAC) and polystyrenesulfonate (PSS) have been investigated on cellulose films with different carboxylic acid contents (20, 350, 870, and 1200 μmol/g) regenerated from oxidized cellulose. The wet cellulose films were thoroughly characterized prior to multilayer deposition using quantitative nanomechanical mapping (QNM), which showed that the mechanical properties were greatly affected by the degree of oxidation of the cellulose. Atomic force microscopy (AFM) force measurements were used to determine the surface potential of the cellulose films by fitting the force data to the DLVO theory. With the exception of the 1200 μmol/g film, the force measurements showed a second-order polynomial increase in surface potential with increasing degree of oxidation. The low surface potential for the 1200 μmol/g film was attributed to the low degree of regeneration of the cellulose film in aqueous media due to increasing solubility with increasing charge. The multilayer formation was characterized using a quartz crystal microbalance with dissipation (QCM-D) and stagnation-point adsorption reflectometry (SPAR). Extensive deswelling was observed for the charged films when pDADMAC was adsorbed due to the reduced osmotic pressure when ions inside the film were released, and the 1:1 charge compensation showed that all the charges in the films were reached by the pDADMAC. The multilayer formation was not significantly affected by the charge density above 350 μmol/g due to interlayer repulsions, but it was strongly affected by the salt concentration during the layer build-up.

  • 88.
    Bergendal, Erik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Fatty Acid Self-Assembly at the Air–Water Interface: Curvature, Patterning, and Biomimetics: A Study by Neutron Reflectometry and Atomic Force Microscopy2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    For more than a hundred years of interfacial science, long chain fatty acids have been the primary system for the study of floating monolayers at the air–water interface due to their amphiphilic nature and system simplicity: an insoluble hydrocarbon chain and a soluble carboxyl group at a flat air–water interface. Despite―or perhaps rather due to―the assumed simplicity of such systems and the maturity of the research field, the seemingly fundamentally rooted notion of a two-dimensional water surface has yet to be challenged.

    The naturally occurring methyl-branched long chain fatty acid 18-methyleicosanoic acid and one of its isomers form monolayers consisting of monodisperse domains of tens of nanometres, varying in size with the placement of the methyl branch. The ability of domain-forming monolayers to three-dimensionally texture the air–water interface is investigated as a result of hydrocarbon packing constraints owing to the methyl branch.

    In this work, neutron reflectometry has been used to study monolayers of branched long chain fatty acids directly at the air–water interface, which allowed precise probing of how a deformable water surface is affected by monolayer structure. Such films were also transferred by Langmuir–Blodgett deposition to the air–solid interface, and subsequently imaged by atomic force microscopy. Combined, the results unanimously―and all but unambiguously―show that the self-assembly of branched long chain fatty acids texture the air–water interface, inducing domain formation by a local curvature of the water surface, and thus controverting the preconceived notion of a planar air–water interface. The size and shape of the observed domains are shown to be tuneable using three different parameters: in mixed systems of branched and unbranched fatty acids, with varying hydrocarbon length of the straight chain, and altering subphase electrolyte properties. Each of these factors effectively allows changing the local curvature of the monolayer, much like analogous three-dimensional systems in bulk lyotropic crystals. This precise tuneability opens up for sustainable nanopatterning. Finally, the results lead to a plausible hypothesis of self-healing properties as to why the surface of hair and wool have a significant proportion of branched fatty acid.

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    (fulltext) Fatty Acid Self-Assembly at the Air–Water Interface
  • 89.
    Bergendal, Erik
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Batista, Marine
    Luengo, Gustavo S.
    L'OREAL Research and Innovation.
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Research Institutes of Sweden AB.
    Self-Assembly Induced Patterning in Biomimetic Fatty Acid MonolayersManuscript (preprint) (Other academic)
  • 90.
    Bergendal, Erik
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Campbell, Richard A.
    Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble, France ; Division of Pharmacy and Optometry, University of Manchester, Manchester M21 9PT, UK .
    Pilkington, Georgia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Müller-Buschbaum, Peter
    Physik-Department, Lehrstuhl für Funktionelle Materialen, Technische Universität München, James-Franck-Str.1, 85748 Garching, Germany ; Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, 85748 Garching, Germany.
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Research Institutes of Sweden, Chemistry, Materials and Surfaces, Box 5607, SE-114 86 Stockholm, Sweden.
    3D texturing of the air–water interface by biomimetic self-assembly2020In: Nanoscale Horizons, ISSN 2055-6764, E-ISSN 2055-6756, no 5, p. 839-846Article in journal (Refereed)
    Abstract [en]

    A simple, insoluble monolayer of fatty acid is shown to induce 3D nanotexturing of the air–water interface. This advance has been achieved through the study of monolayers of a methyl-branched long chain fatty acid, analogous to those found on the surface of hair and wool, directly at the air–water interface. Specular neutron reflectometry combined with AFM probing of deposited monolayers shows pronounced 3D surface domains, which are absent for unbranched analogues and are attributed to hydrocarbon packing constraints. The resulting surface topographies of the water far exceed the height perturbation that can be explained by the presence of capillary waves of a free liquid surface. These have hitherto been considered the only source of perturbation of the flatness of a planar water interface under gravity in the absence of topographical features from the presence of extended, globular or particulate matter. This amounts to a paradigm shift in the study of interfacial films and opens the possibility of 3D texturing of the air–water interface.

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  • 91.
    Bergendal, Erik
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Gutfreund, Philipp
    Pilkington, Georgia A
    Campbell, Richard A
    Holt, Stephen A
    Rutland, Mark W
    Tuneable Self-Assembly Curvature at the Air–Water InterfaceIn: Article in journal (Refereed)
  • 92.
    Bergendal, Erik
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Gutfreund, Philipp
    Inst Laue Langevin, 71 Ave Martyrs, F-38042 Grenoble, France..
    Pilkington, Georgia A.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Campbell, Richard A.
    Inst Laue Langevin, 71 Ave Martyrs, F-38042 Grenoble, France.;Univ Manchester, Div Pharm & Optometry, Manchester M21 9PT, Lancs, England..
    Mueller-Buschbaum, Peter
    Tech Univ Munich, Phys Dept, Lehrstuhl Funkt Mat, James Franch Str 1, D-85748 Garching, Germany.;Tech Univ Munich, Heinz Maier Leibnitz Zentrum MLZ, Lichtenbergstr 1, D-85748 Garching, Germany..
    Holt, Stephen A.
    Australian Nucl Sci & Technol Org, New Illawarra Rd, Lucas Heights, NSW 2232, Australia..
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Res Inst Sweden, Mat & Surface Design, Box 5607, SE-11486 Stockholm, Sweden..
    Tuneable interfacial surfactant aggregates mimic lyotropic phases and facilitate large scale nanopatterning2021In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 13, no 1, p. 371-379Article in journal (Refereed)
    Abstract [en]

    It is shown that the air-liquid interface can be made to display the same rich curvature phenomena as common lyotropic liquid crystal systems. Through mixing an insoluble, naturally occurring, branched fatty acid, with an unbranched fatty acid of the same length, systematic variation in the packing constraints at the air-water interface could be obtained. The combination of atomic force microscopy and neutron reflectometry is used to demonstrate that the water surface exhibits significant tuneable topography. By systematic variation of the two fatty acid proportions, ordered arrays of monodisperse spherical caps, cylindrical sections, and a mesh phase are all observed, as well as the expected lamellar structure. The tuneable deformability of the air-water interface permits this hitherto unexplored topological diversity, which is analogous to the phase elaboration displayed by amphiphiles in solution. It offers a wealth of novel possibilities for the tailoring of nanostructure.

  • 93.
    Bergendal, Erik
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Rutland, Mark W
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Research Institutes of Sweden.
    Texture and Topography of Fatty Acid Langmuir Films: Domain Stability and Isotherm AnalysisIn: Article in journal (Refereed)
  • 94.
    Bergendal, Erik
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Res Inst Sweden Chem Mat & Surfaces, SE-11486 Stockholm, Sweden.;Univ New South Wales, Sch Chem, Sydney, NSW 2052, Australia.;Ecole Cent Lyon, Lab Tribol & Dynam Syst, F-69134 Ecully, France..
    Unveiling Texture and Topography of Fatty Acid Langmuir Films: Domain Stability and Isotherm Analysis2024In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 40, no 20, p. 10468-10476Article in journal (Refereed)
    Abstract [en]

    3D texturing by self-assembly at the air-water interface has recently been proposed. The hypothesis of this work is that, if this is true, such domain formation should be inferable directly from pressure-area isotherms and be thermodynamically stable. Monolayers of branched fatty acid mixtures with straight chain analogues and their stability are thus studied using a combination of pressure-area isotherms, thermodynamic analysis, in situ Brewster angle microscopy, and atomic force microscopy of both LB-deposited and drop-cast films on silicon wafers. Isotherms reflecting the behavior of monodisperse 3D domains are shown to be independent of compression rate and display long-term stability. Gibbs analysis further confirms the thermodynamic rather than kinetic origin of such novel species by revealing that deviations from ideal mixing can be explained only a priori by differences in the topography of the water surface, thus also indirectly confirming the self-assembly deformation of the water interface. The intrinsic self-assembly curvature and miscibility of the two fatty acids is confirmed by drop-casting, which also provides a rapid, tunable thin-film preparation approach. Finally, the longevity of the nanostructured films is extraordinary, the long-range order of the deposited films increases with equilibration time at the water interface, and the integrity of the nanopatterns remains intact on the scale of years.

  • 95.
    Bergenstråhle, Malin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Mazeau, Karim
    CERMAV-CNRS .
    Thermal Response in Crystalline Iβ Cellulose: A Molecular Dynamics Study2007In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 111, no 30, p. 9138-9145Article in journal (Refereed)
    Abstract [en]

    The influence of temperature on structure and properties of the cellulose Iβ crystal was studied by molecular dynamics simulations with the GROMOS 45a4 force-field. At 300 K, the modeled crystal agreed reasonably with several sets of experimental data, including crystal density, corresponding packing and crystal unit cell dimensions, chain conformation parameters, hydrogen bonds, Young's modulus, and thermal expansion coefficient at room temperature. At high-temperature (500 K), the cellulose chains remained in sheets, despite differences in the fine details compared to the room-temperature structure. The density decreased while the a and b cell parameters expanded by 7.4% and 6%, respectively, and the c parameter (chain axis) slightly contracted by 0.5%. Cell angles α and β divided into two populations. The hydroxymethyl groups mainly adopted the gt orientation, and the hydrogen-bonding pattern thereby changed. One intrachain hydrogen bond, O2'H2'···O6, disappeared and consequently the Young's modulus decreased by 25%. A transition pathway between the low- and high-temperature structures has been proposed, with an initial step being an increased intersheet separation, which allowed every second cellulose chain to rotate around its helix axis by about 30°. Second, all hydroxymethyl groups changed their orientations, from tg to gg (rotated chains) and from tg to gt (non-rotated chains). When temperature was further increased, the rotated chains returned to their original orientation and their hydroxymethyl groups again changed their conformation, from gg to gt. A transition temperature of about 450 K was suggested; however, the transition seems to be more gradual than sudden. The simulated data on temperature-induced changes in crystal unit cell dimensions and the hydrogen-bonding pattern also compared well with experimental results.

  • 96.
    Bergenstråhle, Malin
    et al.
    Cornell University.
    Wohlert, Jakob
    Cornell University.
    Brady, John
    Cornell University.
    Himmel, Michael
    National Renewable Energy Laboratory.
    Simulation studies of the insolubility of cellulose2010In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 345, no 14, p. 2060-2066Article in journal (Refereed)
    Abstract [en]

    Molecular dynamics simulations have been used to calculate the potentials of mean force for separating short cellooligomers in aqueous solution as a means of estimating the contributions of hydrophobic stacking and hydrogen bonding to the insolubility of crystalline cellulose. A series of four potential of mean force (pmf) calculations for glucose, cellobiose, cellotriose, and cellotetraose in aqueous solution were performed for situations in which the molecules were initially placed with their hydrophobic faces stacked against one another, and another for the cases where the molecules were initially placed adjacent to one another in a co-planar, hydrogen-bonded arrangement, as they would be in cellulose ID. From these calculations, it was found that hydrophobic association does indeed favor a crystal-like structure over solution, as might be expected. Somewhat more surprisingly, hydrogen bonding also favored the crystal packing, possibly in part because of the high entropic cost for hydrating glucose hydroxyl groups, which significantly restricts the configurational freedom of the hydrogen-bonded waters. The crystal was also favored by the observation that there was no increase in chain configurational entropy upon dissolution, because the free chain adopts only one conformation, as previously observed, but against intuitive expectations, apparently due to the persistence of the intramolecular O3-O5 hydrogen bond.

  • 97.
    Bergenstråhle, Malin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wohlert, Jakob
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Larsson, Per Tomas
    STFI-PACKFORSK AB.
    Mazeau, Karim
    CERMAV-CNRS.
    Berglund, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Dynamics of Cellulose-Water Interfaces: NMR Spin-Lattice Relaxation Times Calculated from Atomistic Computer Simulations2008In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 112, no 9, p. 2590-2595Article in journal (Refereed)
    Abstract [en]

    Solid-state nuclear magnetic resonance (CP/MAS 13C NMR) spectroscopy has often been used to study cellulose structure, but some features of the cellulose NMR spectrum are not yet fully understood. One such feature is a doublet around 84 ppm, a signal that has been proposed to originate from C4 atoms at cellulose fibril surfaces. The two peaks yield different T1, differing by approximately a factor of 2 at 75 MHz. In this study, we calculate T1 from C4-H4 vector dynamics obtained from molecular dynamics computer simulations of cellulose Iβ-water interfacial systems. Calculated and experimentally obtained T1 values for C4 atoms in surface chains fell within the same order of magnitude, 3-20 s. This means that the applied force field reproduces relevant surface dynamics for the cellulose-water interface sufficiently well. Furthermore, a difference in T1 of about a factor of 2 in the range of Larmor frequencies 25-150 MHz was found for C4 atoms in chains located on top of two different crystallographic planes, namely, (110) and (10). A previously proposed explanation that the C4 peak doublet could derive from surfaces parallel to different crystallographic planes is herewith strengthened by computationally obtained evidence. Another suggested basis for this difference is that the doublet originates from C4 atoms located in surface anhydro-glucose units with hydroxymethyl groups pointing either inward or outward. This was also tested within this study but was found to yield no difference in calculated T1.

  • 98.
    Bergman, Astrid
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Alternative Architectures of Quantum Dot Solar Cells2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Quantum dots are of great interest for producing solar cells due to the possibility of tuning the bandgap depending on the quantum dot size. In this Masters's thesis project alternative architectures of PbS quantum dot solar cells have been tested and the influences of different layers have been evaluated. First, a short reproducibility study of the PbS quantum dot solar cell was produced, where it could be seen that the fabricated solar cells gave low efficiencies compared to literature. A comparison of using ZnO or magnesium doped ZnO (MZO) was performed, where the solar cells using MZO performed better than the solar cells using ZnO. Furthermore, the influence of removing the hole compared to the electron transporting layer was tested, where the electron transporting layer proved to be essential for the solar cell to function while it still could function without the hole transporting layer. Additionally, an inverted solar cell structure was tested, but only produced solar cells with efficiencies below 0.09 %. It was also tested to use another ligand solution and solvent for the ligand exchange needed for the light-absorbing quantum dot layer in the solar cell. This was done using ammonium iodide for the ligand exchange to later disperse the quantum dots in propylene carbonate, although the films produced with the new ligand exchange were of poor quality and gave low-efficiency solar cells. Lastly, a short study of the annealing temperature of an MZO thin-film was realised, where it was found that the MZO crystallised at 250℃, 300℃, and 350℃ when annealed for 30 minutes.

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  • 99.
    Bergström, L.
    et al.
    YKI, Institute for Surface Chemistry.
    Blomberg, Eva
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Probing polymeric stabilization in nonaqueous media by direct measurements2000In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 83, no 1, p. 217-219Article in journal (Refereed)
    Abstract [en]

    The steric repulsion induced by adsorbed layers of the commercial dispersant Hypermer KD3 has been probed by direct measurements in decalin. The forces are long range (commencing at 30-40 nm) and repulsive, and the distance dependence can be modeled with a simple scaling theory expression valid for polymer brushes. We obtain layer thicknesses of similar to 9-15 nm for the compressed layers, depending on KD3 concentration, whereas the undisturbed layers have a thickness of similar to 23-24 nm, independent of polymer concentration. Comparison of the measured interaction lengths with previous layer thickness estimates based on rheological studies shows that the polymer layers are compressed in dense suspensions.

  • 100.
    Bergström, L. M.
    et al.
    Department of Pharmacy, Pharmaceutical Physical Chemistry, Uppsala University.
    Bastardo Zambrano, Luis Alejandro
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Garamus, V. M.
    GKSS Research Centre, Geesthacht.
    A small-angle neutron and static light scattering study of micelles formed in aqueous mixtures of a nonionic alkylglucoside and an anionic surfactant2005In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, no 25, p. 12387-12393Article in journal (Refereed)
    Abstract [en]

    The size and shape of micelles formed in aqueous mixtures of the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic sugar-based surfactant n-decyl beta-D-glucopyranoside (C(10)G) at different concentrations of added salt have been investigated with small-angle neutron and static light scattering. Rather small prolate ellipsoidal micelles form in the absence of added salt and at [NaCl] = 10 mM in D2O. The micelles grow considerably in length to large rods as the electrolyte concentration is raised to [NaCl] = 0.1 M. In excess of nonionic surfactant ([SDS]/[C(10)G] = 1:3) at [NaCl] = 0.1 M in D2O, several thousands of Angstroms long wormlike micelles are observed. Most interestingly, a conspicuously large isotope solvent effect was observed from static light scattering data according to which micelles formed at [SDS]/[C(10)G] = 1:3 and [NaCl] = 0.1 M in H2O are at least five times smaller than micelles formed in the corresponding samples in D2O.

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  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf