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  • 1. Abdala, Paula M
    et al.
    Safonova, Olga V
    Wiker, Geir
    van Beek, Wouter
    Emerich, Herman
    van Bokhoven, Jeroen A
    Sá, Jacinto
    Szlachetko, Jakub
    Nachtegaal, Maarten
    Scientific opportunities for heterogeneous catalysis research at the SuperXAS and SNBL beam lines.2012In: Chimia (Basel), ISSN 0009-4293, Vol. 66, no 9, p. 699-705Article in journal (Refereed)
    Abstract [en]

    In this short review, we describe the complementary experimental capabilities for catalysis research at two beam lines available to the Swiss community, SuperXAS at SLS (Swiss Light Source, Villigen) and SNBL (Swiss Norwegian Beam lines) at ESRF (European Synchrotron Radiation Facility, Grenoble). Over the years, these two facilities have been developed to provide powerful techniques for structural studies under in situ and operando conditions. These techniques, X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and X-ray emission spectroscopy (XES) in combination with Raman or infrared spectroscopy provide new avenues for structure-performance studies of catalysts. Several exemplary studies are used to demonstrate the capability of these facilities.

  • 2.
    Abdellah, Mohamed
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. South Valley Univ, Qena Fac Sci, Dept Chem, Qena 83523, Egypt.
    Zhang, Shihuai
    Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Wang, Mei
    Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Competitive Hole Transfer from CdSe Quantum Dots to Thiol Ligands in CdSe-Cobaloxime Sensitized NiO Films Used as Photocathodes for H-2 Evolution2017In: ACS Energy Letters, ISSN 2380-8195, Vol. 2, no 11, p. 2576-2580Article in journal (Refereed)
    Abstract [en]

    Quantum dot (QD) sensitized NiO photocathodes rely on efficient photoinduced hole injection into the NiO valence band. A system of a mesoporous NiO film co-sensitized with CdSe QDs and a molecular proton reduction catalyst was studied. While successful electron transfer from the excited QDs to the catalyst is observed, most of the photogenerated holes are instead quenched very rapidly (ps) by hole trapping at the surface thiols of the capping agent used as linker molecules. We confirmed our conclusion by first using a thiol free capping agent and second varying the thiol concentration on the QD's surface. The later resulted in faster hole trapping as the thiol concentration increased. We suggest that this hole trapping by the linker limits the H-2 yield for this photocathode in a device.

  • 3.
    Abrahamsson, Malin L. A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Berglund Baudin, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Tran, A.
    Philouze, C.
    Berg, K.
    Raymond-Johansson, Mary Katherine
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Sun, L.
    Åkermark, B.
    Styring, S.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Ruthenium-Manganese Complexes for Artificial Photosynthesis: Factors Controlling Intramolecular Electron Transfer and Excited State Quenching Reactions2002In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 41, no 6, p. 1534-1544Article in journal (Refereed)
    Abstract [en]

    Continuing our work toward a system mimicking the electron-transfer steps from manganese to P(680)(+) in photosystem II (PS II), we report a series of ruthenium(II)-manganese(II) complexes that display intramolecular electron transfer from manganese(II) to photooxidized ruthenium(III). The electron-transfer rate constant (k(ET)) values span a large range, 1 x 10(5)-2 x 10(7) s(-1), and we have investigated different factors that are responsible for the variation. The reorganization energies determined experimentally (lambda = 1.5-2.0 eV) are larger than expected for solvent reorganization in complexes of similar size in polar solvents (typically lambda approximately 1.0 eV). This result indicates that the inner reorganization energy is relatively large and, consequently, that at moderate driving force values manganese complexes are not fast donors. Both the type of manganese ligand and the link between the two metals are shown to be of great importance to the electron-transfer rate. In contrast, we show that the quenching of the excited state of the ruthenium(II) moiety by manganese(II) in this series of complexes mainly depends on the distance between the metals. However, by synthetically modifying the sensitizer so that the lowest metal-to-ligand charge transfer state was localized on the nonbridging ruthenium(II) ligands, we could reduce the quenching rate constant in one complex by a factor of 700 without changing the bridging ligand. Still, the manganese(II)-ruthenium(III) electron-transfer rate constant was not reduced. Consequently, the modification resulted in a complex with very favorable properties.

  • 4. Adamska-Venkatesh, Agnieszka
    et al.
    Mirmohades, Mohammad
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Sommer, Constanze
    Reijerse, Edward
    Lubitz, Wolfgang
    Lomoth, Reiner
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Following [FeFe] Hydrogenase Active Site Intermediates by Flash Photolysis/Mid-IR ProbingManuscript (preprint) (Other academic)
  • 5.
    Agmo Hernandez, Victor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Hermes, Michael
    Milchev, Alexander
    Scholz, Fritz
    The overall adhesion-spreading process of liposomes on a mercury electrode is controlled by a mixed diffusion and reaction kinetics mechanism2009In: Journal of Solid State Electrochemistry, ISSN 1432-8488, E-ISSN 1433-0768, Vol. 13, no 4, p. 639-649Article in journal (Refereed)
    Abstract [en]

    Using high-resolution chronoamperometric measurements, with sampling each 1.333 micro s, the initial step of the adhesion-spreading of liposomes on a mercury electrode was studied. These measurements allow getting a deeper insight into the first interaction of the liposomes with the mercury electrode, and they show that the overall adhesion-spreading process at different potentials is partially controlled by a fast but weak interaction equilibrium resulting in a mixed diffusion- and reaction-kinetics-controlled mechanism of the overall reaction.

  • 6.
    Agmo Hernández, Víctor
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    The theory of metal electronucleation applied to the study of fundamental properties of liposomes2013In: Journal of Solid State Electrochemistry, ISSN 1432-8488, E-ISSN 1433-0768, Vol. 17, no 2 (SI), p. 299-305Article, review/survey (Refereed)
    Abstract [en]

    This short review describes how the theory of electrochemical metal nucleation considering non-stationary effects due to the activation of latent nucleation sites has been successfully translated and applied to describe phenomena observed on lipid membranes. This rather unexpected connection is merely formal, but has resulted in a completely new approach in liposome research. It has been proposed that hydrophobic active sites spontaneously and constantly appear and disappear on lipid membranes. These sites control the affinity of liposomes for hydrophobic surfaces and determine the permeability of the lipid membrane to small hydrophilic molecules. Thus, the kinetic models for liposome adhesion on hydrophobic substrates and for the spontaneous leakage of liposomal content are identical to that of non-stationary nucleation mentioned above. Therefore, the broad scope of the available work on metal nucleation has facilitated the interpretation of the data obtained in liposome research. Future applications of the nucleation model in the realm of liposomes are also discussed.

  • 7.
    Agmo Hernández, Víctor
    et al.
    Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Str. 4, 17487 Greifswald, Germany.
    Scholz, Fritz
    Universität Greifswald .
    The lipid composition determines the kinetics of adhesion and spreading of liposomes on mercury electrodes2008In: Bioelectrochemistry, ISSN 1567-5394, E-ISSN 1878-562X, Vol. 74, no 1, p. 149-156Article in journal (Refereed)
    Abstract [en]

    The dependence of membrane properties on their composition was studied by following the adhesion and spreading of unilamellar and multilamellar liposomes on static mercury electrodes with the help of chronoamperometry. The analysis of the peak-shaped signals allows determining the kinetic parameters of the three-step adhesion-spreading process. The presence of cholesterol in the membrane stabilizes the bilayer in the liquid-crystal line phase, and destabilizes the gel phase. The kinetic parameters also show the effect of superlattice formation in the DMPC-cholesterol system. The detergent triton X-100 is only incorporated in the liquid-crystalline DMPC membranes, and it is expelled to the solution when the membrane is transformed to the gel phase. In the liquid-crystalline membrane, it enhances the adhesion-spreading of liposomes on mercury. The lyric peptides mastoparan X and melittin affect the adhesion-spreading in a similar manner. For the rupture-spreading step, their effect is explained by pore formation. The results obtained with lecithins of different length suggest that the bilayer opening process has much in common with flip-flop translocations. For this process the activation energies were found to be independent of the chain length of the lecithin molecules, while the preexponential factor in the Arthenius equation decreases drastically for longer chains.

  • 8. Ahlgren, Sara
    et al.
    Reijmar, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    EGF-targeting lipodisks for specific delivery of cationic amphiphilic peptides to tumour cellsManuscript (preprint) (Other academic)
  • 9.
    Ahlgren, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Reijmar, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Targeting lipodisks enable selective delivery of anticancer peptides to tumor cells2017In: Nanomedicine: Nanotechnology, Biology and Medicine, ISSN 1549-9634, E-ISSN 1549-9642, Vol. 13, no 7, p. 2325-2328Article in journal (Refereed)
    Abstract [en]

    Issues concerning non-specificity, degradation and hemolysis severely hamper the development of membranolytic amphiphilic peptides into safe and efficient anticancer agents. To increase the therapeutic potential, we have previously developed a strategy based on formulation of the peptides in biocompatible nanosized lipodisks. Studies using melittin as model peptide show that the proteolytic degradation and hemolytic effect of the peptide are substantially reduced upon loading in lipodisks. Here, we explored the possibilities to increase the specificity and boost the cytotoxicity of melittin to tumor cells by use of targeting lipodisk. We demonstrate that small (~20 nm) EGF-targeted lipodisks can be produced and loaded with substantial amounts of peptide (lipid/peptide molar ratio >7) by means of a simple and straightforward preparation protocol. In vitro cell studies confirm specific binding of the peptide-loaded disks to tumor cells and suggest that cellular internalization of the disks results in a significantly improved cell-killing effect.

  • 10.
    Ahlstrand, Emma
    et al.
    Linnus Univ, Dept Chem & Biomed Sci, S-39182 Kalmar, Sweden.;Linnus Univ, Ctr Biomat Chem, S-39182 Kalmar, Sweden..
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Friedman, Ran
    Linnus Univ, Dept Chem & Biomed Sci, S-39182 Kalmar, Sweden.;Linnus Univ, Ctr Biomat Chem, S-39182 Kalmar, Sweden..
    Interaction Energies in Complexes of Zn and Amino Acids: A Comparison of Ab Initio and Force Field Based Calculations2017In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 121, no 13, p. 2643-2654Article in journal (Refereed)
    Abstract [en]

    Zinc plays important roles in structural stabilization of proteins, eniyine catalysis, and signal transduction. Many Zn binding sites are located at the interface between the protein and the cellular fluid. In aqueous solutions, Zn ions adopt an octahedral coordination, while in proteins zinc can have different coordinations, with a tetrahedral conformation found most frequently. The dynainics of Zn binding to proteins and the formation of complexes that involve Zn are dictated by interactions between Zn and its binding partners. We calculated the interaction energies between Zn and its ligands in complexes that mimic protein binding sites and in Zn complexes of water and one or two amino acid moieties, using quantum mechanics (QM) and molecular mechanics (MM). It was found that MM calculations that neglect or only approximate polarizability did not reproduce even the relative order of the QM interaction energies in these complexes. Interaction energies calculated with the CHARMM-Diode polarizable force field agreed better with the ab initio results,:although the deviations between QM and MM were still rather large (40-96 kcallmol). In order to gain further insight into Zn ligand interactions, the free energies of interaction were estimated by QM calculations with continuum solvent representation, and we performed energy decomposition analysis calculations to examine the characteristics of the different complexes. The ligand-types were found to have high impact on the relative strength of polarization and electrostatic interactions. Interestingly, ligand ligand interactions did not play a significant role in the binding of Zn. Finally) analysis of ligand exchange energies suggests that carboxylates could be exchanged with water molecules, which explains the flexibility in Zn:binding dynamics. An exchange between earboxylate (Asp/Glii) and imidazole (His) is less likely.

  • 11.
    Aitola, Kerttu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Domanski, Konrad
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, CH-1015 Lausanne, Switzerland..
    Correa-Baena, Juan-Pablo
    MIT, 77 Massachusetts Ave, Cambridge, MA 02139 USA..
    Sveinbjörnsson, Kári
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Saliba, Michael
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, CH-1015 Lausanne, Switzerland..
    Abate, Antonio
    Univ Fribourg, Adolphe Merkle Inst, CH-1700 Fribourg, Switzerland..
    Graetzel, Michael
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, CH-1015 Lausanne, Switzerland..
    Kauppinen, Esko
    Aalto Univ, Dept Appl Phys, POB 15100, Aalto 00076, Finland..
    Johansson, Erik M.J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Tress, Wolfgang
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, CH-1015 Lausanne, Switzerland..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    High Temperature-Stable Perovskite Solar Cell Based on Low-Cost Carbon Nanotube Hole Contact2017In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 29, no 17, article id 1606398Article in journal (Refereed)
    Abstract [en]

    Mixed ion perovskite solar cells (PSC) are manufactured with a metal-free hole contact based on press-transferred single-walled carbon nanotube (SWCNT) film infiltrated with 2,2,7,-7-tetrakis(N, N-di-p-methoxyphenylamine)-9,90-spirobifluorene (Spiro-OMeTAD). By means of maximum power point tracking, their stabilities are compared with those of standard PSCs employing spin-coated Spiro-OMeTAD and a thermally evaporated Au back contact, under full 1 sun illumination, at 60 degrees C, and in a N-2 atmosphere. During the 140 h experiment, the solar cells with the Au electrode experience a dramatic, irreversible efficiency loss, rendering them effectively nonoperational, whereas the SWCNT-contacted devices show only a small linear efficiency loss with an extrapolated lifetime of 580 h.

  • 12.
    Aitola, Kerttu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Sveinbjörnsson, Kári
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Correa-Baena, Juan-Pablo
    Ecole Polytech Fed Lausanne, Lab Photomol Sci, EPFL SB ISIC LSPM, CH G1 523,Chemin Alamb,Stn 6, CH-1015 Lausanne, Switzerland..
    Kaskela, Antti
    Aalto Univ, Sch Sci, Dept Appl Phys, POB 15100, FI-00076 Aalto, Finland..
    Abate, Antonio
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, EPFL SB ISIC LPI, CH G1 526,Stn 6, CH-1015 Lausanne, Switzerland..
    Tian, Ying
    Aalto Univ, Sch Sci, Dept Appl Phys, POB 15100, FI-00076 Aalto, Finland..
    Johansson, Erik M. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Graetzel, Michael
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, EPFL SB ISIC LPI, CH G1 526,Stn 6, CH-1015 Lausanne, Switzerland..
    Kauppinen, Esko I.
    Aalto Univ, Sch Sci, Dept Appl Phys, POB 15100, FI-00076 Aalto, Finland..
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Ecole Polytech Fed Lausanne, Lab Photomol Sci, EPFL SB ISIC LSPM, CH G1 523,Chemin Alamb,Stn 6, CH-1015 Lausanne, Switzerland..
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Carbon nanotube-based hybrid hole-transporting material and selective contact for high efficiency perovskite solar cells2016In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 9, no 2, p. 461-466Article in journal (Refereed)
    Abstract [en]

    We demonstrate a high efficiency perovskite solar cell with a hybrid hole-transporting material-counter electrode based on a thin single-walled carbon nanotube (SWCNT) film and a drop-cast 2,2,7,-7-tetrakis(N, N-di-p-methoxyphenylamine)-9,90-spirobifluorene (Spiro-OMeTAD) hole-transporting material (HTM). The average efficiency of the solar cells was 13.6%, with the record cell yielding 15.5% efficiency. The efficiency of the reference solar cells with spin-coated Spiro-OMeTAD hole-transportingmaterials (HTMs) and an evaporated gold counter electrode was 17.7% (record 18.8%), that of the cells with only a SWCNT counter electrode (CE) without additional HTM was 9.1% (record 11%) and that of the cells with gold deposited directly on the perovskite layer was 5% (record 6.3%). Our results show that it is possible to manufacture high efficiency perovskite solar cells with thin film (thickness less than 1 mu m) completely carbon-based HTMCEs using industrially upscalable manufacturing methods, such as press-transferred CEs and drop-cast HTMs.

  • 13.
    Aitola, Kerttu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Zhang, Jinbao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Vlachopoulos, Nick
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, SB ISIC LSPM, CH-1015 Lausanne, Switzerland..
    Halme, Janne
    Aalto Univ, Sch Sci, Dept Appl Phys, Aalto 00076, Finland..
    Kaskela, Antti
    Aalto Univ, Sch Sci, Dept Appl Phys, Aalto 00076, Finland..
    Nasibulin, Albert G.
    Aalto Univ, Sch Sci, Dept Appl Phys, Aalto 00076, Finland.;Skolkovo Inst Sci & Technol, Skolkovo, Russia..
    Kauppinen, Esko I.
    Aalto Univ, Sch Sci, Dept Appl Phys, Aalto 00076, Finland..
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Carbon nanotube film replacing silver in high-efficiency solid-state dye solar cells employing polymer hole conductor2015In: Journal of Solid State Electrochemistry, ISSN 1432-8488, E-ISSN 1433-0768, Vol. 19, no 10, p. 3139-3144Article in journal (Refereed)
    Abstract [en]

    A semitransparent, flexible single-walled carbon nanotube (SWCNT) film was efficiently used in place of evaporated silver as the counter electrode of a poly(3,4-ethylenedioxythiophene) polymer-based solid-state dye solar cell (SSDSC): the solar-to-electrical energy conversion efficiency of the SWCNT-SSDSC was 4.8 % when it was 5.2 % for the Ag-SSDSC. The efficiency difference stemmed from a 0.1-V difference in the open-circuit voltage, whose reason was speculated to be related to the different recombination processes in the two types of SSDSCs.

  • 14. Aitola, Kerttu
    et al.
    Zhang, Jinbao
    Vlachopoulos, Nick
    Halme, Janne
    Kaskela, Antti
    Nasibulin, Albert
    Kauppinen, Esko
    Boschloo, Gerrit
    Hagfeldt, Anders
    Carbon nanotube film replacing silver in high-efficiency solid-state dye solar cells employing polymer hole conductor2015In: Journal of Solid State ElectrochemistryArticle in journal (Refereed)
    Abstract [en]

    A semitransparent, flexible single-walled carbon nanotube (SWCNT) film was efficiently used in place of evaporated silver as the counter electrode of a poly(3,4-ethylenedioxythiophene) polymer-based solid-state dye solar cell (SSDSC): the solar-to-electrical energy conversion efficiency of the SWCNT-SSDSC was 4.8 % when it was 5.2 % for the Ag-SSDSC. The efficiency difference stemmed from a 0.1-V difference in the open-circuit voltage, whose reason was speculated to be related to the different recombination processes in the two types of SSDSCs.

  • 15.
    Alami, E
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry.
    Almgren, Mats
    Brown, Wyn
    Francois, Jeanette
    Aggregation of hydrophobically end-capped poly(ethylene oxide) in aqueous solutions. Fluorescence and light-scattering studies1996In: MACROMOLECULES, Vol. 29, no 6, p. 2229-2243Article in journal (Refereed)
    Abstract [en]

    The association of a monodisperse model associative polymer, hydrophobically end-capped poly(ethylene oxide), denoted C(12)EO(460)C(12), in aqueous solution has been studied. The macroscopic properties have been investigated by theological methods and cor

  • 16.
    Aldehani, Mohammed
    et al.
    Univ Lancaster, Dept Engn, Lancaster LA1 4YW, England..
    Alzahrani, Faris
    Univ Lancaster, Dept Engn, Lancaster LA1 4YW, England..
    tSaoir, Meabh Nic An
    Queens Univ Belfast, Sch Chem & Chem Engn, Belfast BT7 1NN, Antrim, North Ireland..
    Fernandes, Daniel Luis Abreu
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Assabumrungrat, Suttichai
    Chulalongkorn Univ, Fac Engn, Dept Chem Engn, Ctr Excellence Catalysis & Catalyt React Engn, Bangkok, Thailand..
    Aiouache, Farid
    Univ Lancaster, Dept Engn, Lancaster LA1 4YW, England..
    Kinetics and reactive stripping modelling of hydrogen isotopic exchange of deuterated waters2016In: Chemical Engineering and Processing, ISSN 0255-2701, E-ISSN 1873-3204, Vol. 108, p. 58-73Article in journal (Refereed)
    Abstract [en]

    This work presents results of experimental kinetics and modelling of the isotopic exchange between hydrogen and water in a reactive stripping column for water dedeuteriation. The missing physical properties of deuterium and tritium isotopologues in hydrogen gas and water forms were predicted and validated using existing literature data. The kinetic model relevant to a styrene-divinyl-benzene copolymer-supported platinum catalyst was used for modelling, by Aspen plus modular package, impact of design parameters including temperature, total pressure, gas to liquid flowrate ratio, pressure drop and flow mixing, on the separation of deuterium and further the separation of tritium. The modelling by the rate-based non-equilibrium, including design correlations of model of mass and heat transfers, chemical kinetic constants, mass transfer coefficients and overall exchange rate constants, allowed access to separation trends in a good agreement with published data. The synergy between the rates of chemical isotopic exchange and gas/liquid mass transfer, and by inference the performance of reactive stripping, was particularly sensitive to high temperatures, low hydrogen flow rates, pressure drops and internals properties. Extension to tritium confirmed a slightly slower mass transport compared with deuterium leading to potentially under-estimated design features for detritiation processing when deuterium is used instead.

  • 17.
    Almgren, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Stomatosomes: perforated bilayer structures2010In: Soft Matter, ISSN 1744-683X, Vol. 6, no 7, p. 1383-1390Article, review/survey (Refereed)
    Abstract [en]

    Stomatosomes and related structures formed by perforated fluid bilayer have been identified in a number of systems comprising surfactants and/or lipids. The types of system show a strong variation, but at the same time the conditions allowing such structures to evolve seem rather restrictive. Small changes in the nature of the surfactant can make the perforated bilayers disappear, and also give a major change of the phase behavior. This behavior is exemplified with phase diagrams for systems with CxTAC (alkyltrimethylammonium chloride, x is number of carbons in the alkyl chain; x = 12,14,16) and lipids in brine. On an increase of the spontaneous curvature the perforated bilayers can be found between lamellar bilayers (or smooth vesicles in dilute samples) and cylindrical micelles. The formation of perforations may be understood as a cooperative process starting at a critical concentration of a surfactant in the bilayer. The surfactant promotes the formation of toroidal holes rimmed by hemi cylindrical micelles. With increasing surfactant concentration the surfactant-rich edges increase in length and finally results in bands or cylindrical micelles. Some theoretical calculations on these types of structures are discussed briefly. Observations and theoretical calculations suggest that usually different structures may give similar free-energies, resulting in coexistence of structures and sensitivity to minor effects.

  • 18.
    Andersson, M
    et al.
    Chalmers University of Technology.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ljungstrom, S
    Chalmers University of Technology.
    Palmqvist, A E C
    Chalmers University of Technology.
    Preparation of nanosize anatase and rutile TiO2 by hydrothermal treatment of microemulsions and their activity for photocatalytic wet oxidation of phenol2002In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 106, no 41, p. 10674-10679Article in journal (Refereed)
    Abstract [en]

    Titanium dioxide (TiO2) nanoparticles of both anatase and rutile phases were synthesized by hydrothermal treatment of microemulsions, and their photocatalytic activity for wet oxidation of phenol was studied. The only difference between the two syntheses used was that different acids were added to the microemulsions, making direct comparison of the catalytic activity of the two polymorphs possible. If hydrochloric acid was used, the rutile structure formed, and if nitric acid was used, anatase formed. The phase stability of the microemulsion was studied and according to conductivity and turbidity measurements the idea of a direct template effect could be discarded during the hydrothermal treatment. However, an initial size-templating phenomenon is possible during the mixing step. The particles, which were in the size range of a few nanometers were characterized with N-2-adsorption; XRD, SEM, and XPS. The activity of the two polymorphs for the photocatalytic oxidation of phenol in water was examined. It was shown that the rutile phase initially decomposed phenol much faster and follows a first-order process reasonably well (k = 4 x 10(-5) s(-1)). The photodecomposition process using the anatase phase led, however, to a much more rapid overall degradation following an initial slower rate of phenol oxidation. The results indicate that the observed difference of the photodecomposition process for the two TiO2 phases is due to the formation of different intermediates.

  • 19.
    Andersson, Margaretha
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Surface Biotechnology. Department of Physical and Analytical Chemistry, Surface Biotechnology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry.
    Fromell, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Surface Biotechnology. Department of Physical and Analytical Chemistry, Surface Biotechnology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry.
    Gullberg, Elisabet
    Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmacy. Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Artursson, Per
    Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmacy. Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Caldwell, Karin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Surface Biotechnology. Department of Physical and Analytical Chemistry, Surface Biotechnology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry.
    Characterization of Surface-Modified Nanoparticles for in Vivo Biointeraction. A Sedimentation Field Flow Fractionation Study2005In: Analytical Chemistry, Vol. 77, p. 5488-5493Article in journal (Refereed)
    Abstract [en]

    Sedimentation field flow fractionation (SdFFF) is an emerging high-performance analytical tool for separation and determination of size and adsorption characteristics of colloidal particles. This study demonstrates how SdFFF can be used to characterize nanoparticles prepared for in vivo applications including (1) the quantification of polymer uptake on nanoparticles where surface coverage is crucial and (2) the coupling of cell adhesive peptides containing the Arg-Gly-Asp motif (RGD). Quantitative information about polymer adhesion in order to prepare a bioinert surface and an accurate determination of ligand uptake are both of obvious importance for the understanding of, for example, relations between the number of attached molecules for biointeraction and an observed therapeutic effect. In addition, the present work highlights the necessity to perform careful characterization of commercially available particulate starting materials, in terms of size and polydispersity, prior to biological experimentation.

  • 20.
    Andersson, Martin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Phase Phenomena in Polymer Networks: Empirical Studies on the Influence of Hydrophobicity, Charge Density and Crosslinks on Macroion-Induced Phase Transitions in Polyelectrolyte Gels2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis concerns polyelectrolyte gels in contact with oppositely charged proteins and surfactant micelles, and includes of four papers (I-IV). In paper I confocal Raman spectroscopy was introduced as a method to trace micelles and investigate the structure of gel-surfactant complexes, in phase separated gel spheres. In paper II, the binding of surfactants to microspheres (~50-100 µm) was investigated by means of a micromanipulator-assisted microscopy method. The two surfactants were found to display qualitative difference respect to degree of swelling, surfactant distribution in the gels, and the difference is discussed in terms of absence/presence of hydrophobic attraction to the polyelectrolyte gel network. Kinetics of volume change in gels were analyzed. Aggregation numbers of micelles in polystyrenesulfonate (PSS) solutions, obtained from fluorescence quenching measurements, are presented. In paper III, phase behaviour, protein assembly and diffusion, was studied in PSS gel microspheres. Interpretation of results was aided by measurements of osmotic swelling of individual gel networks, and by combining the results with studies of protein diffusion in macroscopic (cm-sized) gel spheres. Complexes formed were further analyzed with small angle x-ray spectroscopy. In paper IV phase behaviour of mixed ionic/nonionic surfactant micelles is investigated in cm-sized gel spheres. The coexistence of three phases, the formation of dense shells in the bulk of the gels and other phenomena are described for the first time, and the results are presented along with discussion on the charge-density of spherical micelles and of  network induced hysteresis effects in gels. The composition and microstructure of phases are investigated by confocal Raman spectroscopy and small-angle x-ray scattering respectively. The results are interpreted with aid of highly detailed theoretical model calculations.

    List of papers
    1. Differences in binding of a cationic surfactant to cross-linked sodium poly(acrylate) and sodium poly(styrene sulfonate) studied by Raman spectroscopy
    Open this publication in new window or tab >>Differences in binding of a cationic surfactant to cross-linked sodium poly(acrylate) and sodium poly(styrene sulfonate) studied by Raman spectroscopy
    2005 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, no 7, p. 2761-2765Article in journal (Refereed) Published
    Abstract [en]

    Raman spectroscopy has been used to investigate the structure of gel-surfactant complexes. Cross-linked sodium poly(acrylate) and sodium poly(styrene sulfonate) were immersed in solutions of the cationic surfactant dodecyl trimethylammonium bromide. During the deswelling process, two distinct regions could be observed for both types of gels. Looking at the Raman spectra, however, for the poly(styrene sulfonate), the surfactant could be found throughout the gel particle, whereas for poly(acrylate), essentially all the surfactant was bound in a surface layer.

    National Category
    Inorganic Chemistry
    Research subject
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-70227 (URN)10.1021/la0468693 (DOI)15779946 (PubMedID)
    Available from: 2008-12-16 Created: 2008-12-16 Last updated: 2017-11-21
    2. Single microgel particle studies demonstrate the influence of hydrophobic interactions between charged micelles and oppositely charged polyions.
    Open this publication in new window or tab >>Single microgel particle studies demonstrate the influence of hydrophobic interactions between charged micelles and oppositely charged polyions.
    2005 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, no 9, p. 3773-3781Article in journal (Refereed) Published
    Abstract [en]

    The binding of two cationic surfactants, dodecyltrimethylammonium bromide (DoTAB) and N-(1,1,2,2-tetrahydroperfluorodecanyl)pyridinium bromide (HFDePB), to covalently cross-linked sodium poly(styrenesulfonate) (PSS) microgels has been investigated by means of micromanipulator-assisted time-resolved light microscopy on single gels. It is demonstrated that repeated measurements on the same microgel under conditions of controlled liquid flow give highly reproducible results. The two surfactants are found to behave very differently with respect to degree of swelling, surfactant distribution in the gels, both during shrinking and at equilibrium, and kinetics of volume changes induced by them. The main difference is attributed to the presence of a hydrophobic interaction between PSS and the DoTAB micelles, absent in the case of HFDePB. Kinetic shrinking curves are recorded and analyzed using a model for steady-state transport of surfactant between the solution and the gels. Aggregation numbers for DoTAB in PSS solutions obtained from fluorescence quenching measurements are presented. A strong dependence on the surfactant-to-polyion concentration ratio is observed. Relations between surfactant binding isotherms, phase diagrams for linear polyelectrolyte/surfactant/water systems, and the binding to gels are discussed.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:uu:diva-92344 (URN)10.1021/la047316v (DOI)15835936 (PubMedID)
    Available from: 2004-10-29 Created: 2004-10-29 Last updated: 2017-12-14Bibliographically approved
    3. Lysozyme Incorporation in Poly(styrenesulfonate) Microspheres: Dynamics of Core/Shell formation
    Open this publication in new window or tab >>Lysozyme Incorporation in Poly(styrenesulfonate) Microspheres: Dynamics of Core/Shell formation
    (English)Manuscript (preprint) (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-145378 (URN)
    Available from: 2011-02-08 Created: 2011-02-08 Last updated: 2011-02-24
    4. Mixed Micelles in Spherical Polyelectrolyte Networks: Influence of Crosslinks on Charge Induced Phase Separation
    Open this publication in new window or tab >>Mixed Micelles in Spherical Polyelectrolyte Networks: Influence of Crosslinks on Charge Induced Phase Separation
    (English)Manuscript (preprint) (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-145379 (URN)
    Available from: 2011-02-08 Created: 2011-02-08 Last updated: 2011-02-24
  • 21.
    Andersson, Mikael
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry.
    Linke, Myriam
    Chambron, Jean-Claude
    Davidsson, Jan
    Heitz, Valérie
    Hammarström, Leif
    Sauvage, Jean-Pierre
    Long-Range Electron Transfer in Porphyrin-Containing [2]-Rotaxanes: Tuning the Rate by Metal Cation Coordination2002In: J. Am. Chem. Soc. (JACS), Vol. 124, p. 4347-4362Article in journal (Refereed)
  • 22.
    Andersson, Per Ola
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. FOI Swedish Def Res Agcy, CBRN Def & Secur, SE-90182 Umea, Sweden.
    Lejon, Christian
    FOI Swedish Def Res Agcy, CBRN Def & Secur, SE-90182 Umea, Sweden..
    Mikaelsson, Therese
    Swedish Armed Forces, Natl CBRN Def Ctr, SE-90182 Umea, Sweden..
    Landstrom, Lars
    FOI Swedish Def Res Agcy, CBRN Def & Secur, SE-90182 Umea, Sweden..
    Towards Fingermark Dating: A Raman Spectroscopy Proof-of-Concept Study2017In: ChemistryOpen, ISSN 2191-1363, Vol. 6, no 6, p. 706-709Article in journal (Refereed)
    Abstract [en]

    Fingermarks have, for a long time, been vital in the forensic community for the identification of individuals, and a possibility to non-destructively date the fingermarks would of course be beneficial. Raman spectroscopy is, herein, evaluated for the purpose of estimating the age of fingermarks deposits. Well-resolved spectra were non-destructively acquired to reveal spectral uniqueness, resembling those of epidermis, and several molecular markers were identified that showed different decay kinetics: carotenoids > squalene > unsaturated fatty acids > proteins. The degradation rates were accelerated, less pronounced for proteins, when samples were stored under ambient light conditions, likely owing to photo-oxidation. It is hypothesized that fibrous proteins are present and that oxidation of amino acid side chains can be observed both through Raman and fluorescence spectroscopy. Clearly, Raman spectroscopy is a useful technique to non-destructively study the aging processes of fingermarks.

  • 23.
    Andersson, Renée
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry.
    Kadi, Malin
    Davidsson, Jan
    Hansson, Tony
    Photoionisation of molecular wavwpackets - the NaK(C1S+) case2002In: Chemical Physics Letters, Vol. 352, p. 106-112Article in journal (Refereed)
  • 24.
    Antila, Liisa J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ghamgosar, Pedram
    Maji, Somnath
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Tian, Haining
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Dynamics and Photochemical H-2 Evolution of Dye-NiO Photocathodes with a Biomimetic FeFe-Catalyst2016In: ACS ENERGY LETTERS, ISSN 2380-8195, Vol. 1, no 6, p. 1106-1111Article in journal (Refereed)
    Abstract [en]

    Mesoporous NiO films were cosensitized with a coumarin 343 dye and a proton reduction catalyst of the [Fe-2(CO)(6)(bdt)] (bdt = benzene-1,2-dithiolate) family. Femtosecond ultraviolet visible transient absorption experiments directly demonstrated subpicosecond hole injection into NiO from excited dyes followed by rapid (t(50%) similar to 6 ps) reduction of the catalyst on the surface with similar to 70% yield. The reduced catalyst was long-lived (2 mu s to 20 ms), which may allow protonation and a second reduction step of the catalyst to occur. A photo electrochemical device based on this photocathode produced H-2 with a Faradaic efficiency of similar to 50%. Fourier transform infrared spectroscopy and gas chromatography experiments demonstrated that the observed device deterioration with time was mainly due to catalyst degradation and desorption from the NiO surface. The insights gained from these mechanistic studies, regarding development of dye-catalyst cosensitized photocathodes, are discussed.

  • 25.
    Araujo, Rafael B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Appl Mat Phys, Dept Mat & Engn, S-10044 Stockholm, Sweden..
    Evaluating bulk Nb2O2F3 for Li-battery electrode applications2016In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 5, p. 3530-3535Article in journal (Refereed)
    Abstract [en]

    This investigation has the primary objective of elucidating the lithium intercalation process in the crystal structure of a new niobium oxyfluoride compound Nb2O2F3. The framework of the density functional theory was applied in a generalized gradient approximation together with the hybrid functional method. It is revealed that lithium atoms intercalate in this material in a maximum concentration of one Li atom per formula unit forming LiNb2O2F3. Moreover, octahedral positions in between the layers of Nb-O-F appear as the Li preferred occupancy resulting in a structural volume expansion of only 5%. Electronic structure evolution with the insertion of lithium displays a transformation from semi-conductor to metal when half of the lithium atoms are added. This transformation occurs due to a symmetry break induced by the transition from the + 8 to + 7 oxidation state of half of the Nb2 dimers. Then, after full lithiation the symmetry is recovered and the material becomes a semiconductor again with a band gap amounting to 1 eV. The evaluated average deintercalation potential reaches 1.29 V vs. Li/Li+ with activation energy for lithium ion migration of 0.79 eV. The computed low potential of the redox reaction Nb-2(8+) to Nb-2(7+) includes niobium oxyfluoride in the map of possible materials for the anode application of Li-ion batteries.

  • 26.
    Araujo, Rafael B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Unveiling the charge migration mechanism in Na2O2: implications for sodium-air batteries2015In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 17, no 12, p. 8203-8209Article in journal (Refereed)
    Abstract [en]

    Metal-air batteries have become promising candidates for modern energy storage due to their high theoretical energy density in comparison to other storage devices. The lower overpotential of Na compared with Li makes Na-air batteries more efficient in terms of battery lifetime. Additionally, the abundance of Na over Li is another advantage for Na batteries compared to Li batteries. Na2O2 is one of the main products of sodium-air battery reactions. The efficiency of air cells is always related to the charge transport mechanisms in the formed product. To unveil these diffusion mechanisms in one of the main products of the cell reaction Na-O-2 we systematically investigate the mobility of charge carriers as well as the electronic structural properties of sodium peroxide. The framework of the density functional theory based on hybrid functional approach is used to study the mobility of charge carriers and intrinsic defects in Na2O2. Our calculations reveal that the formation of small electron and hole polarons is preferentially occurring over the delocalized state in the crystal structure of Na2O2. The migration of these small polarons displays activation energies of about 0.92 eV and 0.32 eV for the electron and hole polarons respectively, while the analysis of the charged sodium vacancy mobility reveals an activation energy of about 0.5 eV. These results suggest that the charge transport in sodium peroxide would mainly occur through the diffusion of hole polarons.

  • 27.
    Araujo, Rafael B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Barpanda, Prabeer
    Indian Inst Sci, Faraday Mat Lab, Mat Res Ctr, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Appl Mat Phys, Dept Mat & Engn, S-10044 Stockholm, Sweden..
    Na2M2(SO4)(3) (M = Fe, Mn, Co and Ni): towards high-voltage sodium battery applications2016In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 14, p. 9658-9665Article in journal (Refereed)
    Abstract [en]

    Sodium-ion-based batteries have evolved as excellent alternatives to their lithium-ion-based counterparts due to the abundance, uniform geographical distribution and low price of Na resources. In the pursuit of sodium chemistry, recently the alluaudite framework Na2M2(SO4)(3) has been unveiled as a high-voltage sodium insertion system. In this context, the framework of density functional theory has been applied to systematically investigate the crystal structure evolution, density of states and charge transfer with sodium ions insertion, and the corresponding average redox potential, for Na2M2(SO4)(3) (M = Fe, Mn, Co and Ni). It is shown that full removal of sodium atoms from the Fe-based device is not a favorable process due to the 8% volume shrinkage. The imaginary frequencies obtained in the phonon dispersion also reflect this instability and the possible phase transition. This high volume change has not been observed in the cases of the Co- and Ni-based compounds. This is because the redox reaction assumes a different mechanism for each of the compounds investigated. For the polyanion with Fe, the removal of sodium ions induces a charge reorganization at the Fe centers. For the Mn case, the redox process induces a charge reorganization of the Mn centers with a small participation of the oxygen atoms. The Co and Ni compounds present a distinct trend with the redox reaction occurring with a strong participation of the oxygen sublattice, resulting in a very small volume change upon desodiation. Moreover, the average deintercalation potential for each of the compounds has been computed. The implications of our findings have been discussed both from the scientific perspective and in terms of technological aspects.

  • 28.
    Arteca, G A
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry.
    Reimann, C T
    Tapia, O
    Role of electrostatic and van der Waals interactions on the in vacuo unfolding dynamics of lysozyme ions2001In: Chemical Physics Letters, Vol. 350, p. 277-285Article in journal (Refereed)
  • 29.
    Arteca, G A
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry.
    Tapia, O
    Protein Denaturation in Vacuo. Behavior of the Four-a-Helix Bundle of Apotochrome c' under Centrifugal Unfolding Conditions2002In: Journal of Physical Chemistry B, Vol. 106, p. 1081-1089Article in journal (Refereed)
  • 30.
    Arteca, Gustavo A.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical Chemistry.
    Reimann, C.T.
    Tapia, O.
    Proteins in vacuo: Denaturing and folding mechanisms studied with computersimulated molecular dynamics2001In: Mass Spectrometry Reviews, Vol. 20, p. 402-422Article in journal (Refereed)
  • 31. Arteca, Gustavo A.
    et al.
    Tapia, Orlando
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Quantum states for quantum processes: A toy model for ammonia inversion spectra2011In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 84, no 1, p. 012115-Article in journal (Refereed)
    Abstract [en]

    Chemical transformations are viewed here as quantum processes modulated by external fields, that is, as shifts in reactant to product amplitudes within a quantum state represented by a linear (coherent) superposition of electronuclear basis functions; their electronic quantum numbers identify the "chemical species." This basis set can be mapped from attractors built from a unique electronic configurational space that is invariant with respect to the nuclear geometry. In turn, the quantum numbers that label these basis functions and the semiclassical potentials for the electronic attractors may be used to derive reaction coordinates to monitor progress as a function of the applied field. A generalization of Feynman's three-state model for the ammonia inversion process illustrates the scheme; to enforce symmetry for the entire inversion process model and ensure invariance with respect to nuclear configurations, the three attractors and their basis functions are computed with a grid of fixed floating Gaussian functions. The external-field modulation of the effective inversion barrier is discussed within this conceptual approach. This analysis brings the descriptions of chemical processes near modern technologies that employ molecules to encode information by means of confinement and external fields.

  • 32.
    Arteca, Gustavo
    et al.
    Département de Chimie et Biochimie and Biomolecular Sciences Programme, Laurentian University.
    Rank, Jean Pierre
    Département de Chimie et Biochimie and Biomolecular Sciences Programme, Laurentian University.
    Tapia, Orlando
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Physical Chemistry.
    Simulating trends in reaction path geometry as a function of external fields: A generalized electronic diabatic model for two-dimensional energy surfaces2008In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 108, no 10, p. 1810-1820Article in journal (Refereed)
    Abstract [en]

    We introduce a protocol to represent quantum states as a linear superposition of model electronic diabatic basis states coupled in an external (static) elec. field. By considering an entire family of these models, we uncover trends in reaction-path geometry and the topol. of potential-energy surfaces, including all those that can be realized in a two-dimensional configurational space. Our approach can be used as a tool to model the key parameters (e.g., diabatic basis states, external field intensity) that yield desired geometrical characteristics in an actual potential energy surface. In this work, external agents such as laser fields, or a group of neighboring charges, are regarded as essential requirements to prompt, or trigger, the occurrence of a chem. process. In these cases, reaction path geometry can be modulated externally so as to yield processes that would appear to occur far from gas-phase geometries. This phenomenol. is intrinsically nonadiabatic. Our present approach accounts for the possibility of such features, i.e., the occurrence of quantum states whose electronic structures resemble products, while at geometries that are more similar to those of reactants.

  • 33.
    Asfaw, Habtom Desta
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Multifunctional Carbon Foams by Emulsion Templating: Synthesis, Microstructure, and 3D Li-ion Microbatteries2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Carbon foams are among the existing electrode designs proposed for use in 3D Li-ion microbatteries. For such electrodes to find applications in practical microbatteries, however, their void sizes, specific surface areas and pore volumes need be optimized. This thesis concerns the synthesis of highly porous carbon foams and their multifunctional applications in 3D microbatteries. The carbon foams are derived from polymers that are obtained by polymerizing high internal phase water-in-oil emulsions (HIPEs).

    In general, the carbonization of the sulfonated polymers yielded hierarchically porous structures with void sizes ranging from 2 to 35 µm and a BET specific surface area as high as 630 m2 g-1. Thermogravimetric and spectroscopic evidence indicated that the sulfonic acid groups, introduced during sulfonation, transformed above 250 oC to thioether (-C-S-) crosslinks which were responsible for the thermal stability and charring tendency of the polymer precursors. Depending on the preparation of the HIPEs, the specific surface areas and void-size distributions were observed to vary considerably. In addition, the pyrolysis temperature could also affect the microstructures, the degree of graphitization, and the surface chemistry of the carbon foams.

    Various potential applications were explored for the bespoke carbon foams. First, their use as freestanding active materials in 3D microbatteries was studied. The carbon foams obtained at 700 to 1500 oC suffered from significant irreversible capacity loss during the initial discharge. In an effort to alleviate this drawback, the pyrolysis temperature was raised to 2200 oC. The resulting carbon foams were observed to deliver high, stable areal capacities over several cycles. Secondly, the possibility of using these structures as 3D current collectors for various active materials was investigated in-depth. As a proof-of-concept demonstration, positive active materials like polyaniline and LiFePO4 were deposited on the 3D architectures by means of electrodeposition and sol-gel approach, respectively. In both cases, the composite electrodes exhibited reasonably high cyclability and rate performance at different current densities. The syntheses of niobium and molybdenum oxides and their potential application as electrodes in microbatteries were also studied. In such applications, the carbon foams served dual purposes as 3D scaffolds and as reducing reactants in the carbothermal reduction process. Finally, a facile method of coating carbon substrates with oxide nanosheets was developed. The approach involved the exfoliation of crystalline VO2 to prepare dispersions of hydrated V2O5, which were subsequently cast onto CNT paper to form oxide films of different thicknesses.

    List of papers
    1. Boosting the thermal stability of emulsion–templated polymers via sulfonation: an efficient synthetic route to hierarchically porous carbon foams
    Open this publication in new window or tab >>Boosting the thermal stability of emulsion–templated polymers via sulfonation: an efficient synthetic route to hierarchically porous carbon foams
    Show others...
    2016 (English)In: ChemistrySelect, ISSN 2365-6549, Vol. 1, no 4, p. 784-792Article in journal (Refereed) Published
    Abstract [en]

    Hierarchically porous carbon foams with specific surface areas exceeding 600 m2 g−1 can be derived from polystyrene foams that are synthesized via water-in-oil emulsion templating. However, most styrene-based polymers lack strong crosslinks and are degraded to volatile products when heated above 400 oC. A common strategy employed to avert depolymerization is to introduce potential crosslinking sites such as sulfonic acids by sulfonating the polymers. This article unravels the thermal and chemical processes leading up to the conversion of sulfonated high internal phase emulsion polystyrenes (polyHIPEs) to sulfur containing carbon foams. During pyrolysis, the sulfonic acid groups (-SO3H) are transformed to sulfone (-C-SO2-C-) and then to thioether (-C−S-C-) crosslinks. These chemical transformations have been monitored using spectroscopic techniques: in situ IR, Raman, X-ray photoelectron and X-ray absorption near edge structure spectroscopy. Based on thermal analyses, the formation of thioether links is associated with increased thermal stability and thus a substantial decrease in volatilization of the polymers.

    Keywords
    Emulsion-templated polymer, sulfonation, pyrolysis, spectroscopy, carbon foam
    National Category
    Materials Chemistry
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-283174 (URN)10.1002/slct.201600139 (DOI)000395395900026 ()
    Projects
    3D microbatteries
    Available from: 2016-04-11 Created: 2016-04-11 Last updated: 2017-10-30Bibliographically approved
    2. Emulsion-templated bicontinuous carbon network electrodes for use in 3D microstructured batteries
    Open this publication in new window or tab >>Emulsion-templated bicontinuous carbon network electrodes for use in 3D microstructured batteries
    2013 (English)In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 1, no 44, p. 13750-13758Article in journal (Refereed) Published
    Abstract [en]

    High surface area carbon foams were prepared and characterized for use in 3D structured batteries. Twopotential applications exist for these foams: firstly as an anode and secondly as a current collector supportfor electrode materials. The preparation of the carbon foams by pyrolysis of a high internal phase emulsionpolymer (polyHIPE) resulted in structures with cage sizes of 25 mm and a surface area enhancement pergeometric area of approximately 90 times, close to the optimal configuration for a 3D microstructuredbattery support. The structure was probed using XPS, SEM, BET, XRD and Raman techniques; revealingthat the foams were composed of a disordered carbon with a pore size in the <100 nm range resultingin a BET measured surface area of 433 m2 g-1. A reversible capacity exceeding 3.5 mA h cm2 at acurrent density of 0.37 mA cm-2 was achieved. SEM images of the foams after 50 cycles showed thatthe structure suffered no degradation. Furthermore, the foams were tested as a current collector bydepositing a layer of polyaniline cathode over their surface. High footprint area capacities of500 mA h cm-2 were seen in the voltage range 3.8 to 2.5 V vs. Li and a reasonable rate performancewas observed.

    Place, publisher, year, edition, pages
    United Kingdom: , 2013
    Keywords
    Carbon foam, High internal phase emulsion polymer, microbattery, 3D microbattery, Lithium ion
    National Category
    Chemical Sciences Materials Chemistry
    Research subject
    Materials Science; Chemistry; Materials Science; Physical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-210659 (URN)10.1039/C3TA12680C (DOI)000326463400009 ()
    Projects
    STEM-VR-Microbattery
    Funder
    Swedish Energy AgencySwedish Research Council
    Available from: 2013-11-12 Created: 2013-11-12 Last updated: 2017-12-06Bibliographically approved
    3. Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteries
    Open this publication in new window or tab >>Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteries
    (English)Manuscript (preprint) (Other academic)
    Keywords
    carbon, foam, graphitic, anode, three-dimensional, microbattery, lithium
    National Category
    Polymer Technologies Chemical Process Engineering Materials Chemistry Polymer Chemistry Inorganic Chemistry Physical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-312893 (URN)
    Funder
    Swedish Research Council, 2012–4681StandUp
    Available from: 2017-01-14 Created: 2017-01-14 Last updated: 2017-12-30
    4. Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance
    Open this publication in new window or tab >>Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance
    Show others...
    2014 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 15, p. 8804-8813Article in journal (Refereed) Published
    Abstract [en]

    In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol–gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm−2 at 0.1 mA cm−2 (lowest rate) and 1.1 mA h cm−2 at 6 mA cm−2(highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.

    Place, publisher, year, edition, pages
    Royal Society of Chemistry: , 2014
    National Category
    Physical Chemistry Polymer Chemistry Materials Chemistry Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-228630 (URN)10.1039/C4NR01682C (DOI)000339861500051 ()
    Projects
    STEM-VR-Microbattery
    Available from: 2014-07-18 Created: 2014-07-18 Last updated: 2017-12-05Bibliographically approved
    5. Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteries
    Open this publication in new window or tab >>Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteries
    (English)Manuscript (preprint) (Other academic)
    Keywords
    niobium, oxide, nanoparticle, power, energy, carbon, foam, lithium, microbattery
    National Category
    Natural Sciences Inorganic Chemistry Materials Chemistry Physical Chemistry Condensed Matter Physics Materials Engineering Chemical Engineering
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-312894 (URN)
    Projects
    3D Lithium-ion microbattery
    Funder
    Swedish Research Council, 2012–4681StandUp
    Available from: 2017-01-14 Created: 2017-01-14 Last updated: 2017-12-30
    6. A one-step water based strategy for synthesizing hydrated vanadium pentoxide nanosheets from VO2(B) as free-standing electrodes for lithium battery applications
    Open this publication in new window or tab >>A one-step water based strategy for synthesizing hydrated vanadium pentoxide nanosheets from VO2(B) as free-standing electrodes for lithium battery applications
    Show others...
    2016 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 46, p. 17988-18001Article in journal (Refereed) Published
    Abstract [en]

    The synthesis of two dimensional (2D) materials from transition metal oxides, chalcogenides, and carbides mostly involve multiple exfoliation steps in which hazardous solvents and reagents are used. In this study, hydrated vanadium pentoxide (V2O5[middle dot]nH2O) nanosheets with a thickness of a few nanometers were prepared via a facile environmentally friendly water based exfoliation technique. The exfoliation process involved refluxing the precursor, vanadium dioxide (VO2(B)), in water for a few days at 60 [degree]C. The proposed exfoliation mechanism is based on the intercalation/insertion of water molecules into the VO2(B) crystals and the subsequent cleavage of the covalent bonds holding the layers of VO2(B) together. The thermal and chemical analyses showed that the approximate chemical composition of the nanosheets is H0.4V2O5[middle dot]0.55H2O, and the percentage of VV content to that of VIV in the nanosheets is about 80(3)% to 20(3)%. The exfoliated aqueous suspension of the V2O5[middle dot]0.55H2O nanosheets was successfully deposited onto multi-walled carbon nanotube (MW-CNT) paper to form free-standing electrodes with a thickness of the V2O5[middle dot]0.55H2O layer ranging between 45 and 4 [small mu ]m. A series of electrochemical tests were conducted on the electrodes to determine the cyclability and rate capability of lithium insertion into V2O5[middle dot]0.55H2O nanosheets. The electrodes with the thinnest active material coating ([similar]4 [small mu ]m) delivered gravimetric capacities of up to 480 and 280 mA h g-1 when cycled at current densities of 10 and 200 mA g-1, respectively.

    Keywords
    2D materials, vanadium oxides, free-standing, battery, lithium
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-311357 (URN)10.1039/C6TA06571F (DOI)000388505400010 ()
    Funder
    Swedish Research Council, 2012-4681Swedish Energy AgencyBerzelii Centre EXSELENTStandUp
    Available from: 2016-12-24 Created: 2016-12-24 Last updated: 2017-12-30
  • 34.
    Asfaw, Habtom Desta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Roberts, Matthew R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Tai, Cheuk-Wai
    Stockholm University.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. DTU.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 15, p. 8804-8813Article in journal (Refereed)
    Abstract [en]

    In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol–gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm−2 at 0.1 mA cm−2 (lowest rate) and 1.1 mA h cm−2 at 6 mA cm−2(highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.

  • 35.
    Asfaw, Habtom Desta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteriesManuscript (preprint) (Other academic)
  • 36.
    Asfaw, Habtom Desta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteriesManuscript (preprint) (Other academic)
  • 37.
    Asfaw, Habtom
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteriesManuscript (preprint) (Other academic)
  • 38. Awais, Muhammad
    et al.
    Gibson, Elizabeth
    Vos, Johannes G.
    Dowling, Denis P.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Dini, Danilo
    Fabrication of Efficient NiO Photocathodes Prepared via RDS with Novel Routes of Substrate Processing for p-Type Dye-Sensitized Solar Cells2014In: CHEMELECTROCHEM, ISSN 2196-0216, Vol. 1, no 2, p. 384-391Article in journal (Refereed)
    Abstract [en]

    p-type dye sensitized solar cells (p-DSCs) derived from nickel oxide (NiO) photocathodes have been obtained via rapid discharge sintering (RDS) of parent metal oxide nanoparticles deposited onto differently treated substrates utilizing a plasma atmosphere with microwave radiation as heat source. This method produces NiO thin films (0.6 < l < 6 mu m) with mesoporous features and large surface areas as required for efficient dye-loading and high photocurrents. Erythrosine B (ERY) was used to sensitize the oxide in the visible spectrum. We have analyzed and compared the photoelectrochemical performances of the p-DSCs assembled with the various types of NiO samples prepared by RDS techniques with different treatments of the supporting substrate prior to, or during, spray deposition of the NiO nanoparticles. The best photovoltaic performances were obtained when the transparent conducting substrate (TCS) was heated during spraying. We believe that this is because the charge transfer through the NiO film and the charge collection at the TCS/NiO film interface were the most efficient with this sample. To our knowledge, the photovoltaic performances reported here are the best achieved with the commercial dye ERY as sensitizer.

  • 39.
    Azuma, Tomoyuki
    et al.
    Univ Tokyo, Dept Bioengn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Teramura, Yuji
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology. Univ Tokyo, Dept Bioengn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan.
    Hoshi, Toru
    Nihon Univ, Dept Mat & Appl Chem, Coll Sci & Technol, Tokyo 1018308, Japan..
    Takai, Madoka
    Univ Tokyo, Dept Bioengn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Enhancement of Cell Adhesion on a Phosphorylcholine-Based Surface through the Interaction with DNA Mediated by Ca2+ Ions2016In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 120, no 48, p. 12272-12278Article in journal (Refereed)
    Abstract [en]

    2-Methacryloyloxyethyl phosphorylcholine (MPC) has a PC group and is one of the most well-known bioinert polymers. In this study, we evaluated the interaction between MPC and DNA, which specifically interacts with the phospholipid head group via Ca2+ ions. A MPC monolayer and poly(MPC) brush were fabricated to observe the effect of the structure on the interaction between MPC and DNA via Ca2+ ions. The poly(MPC) brush, which shows higher MPC unit density, more efficiently interacted with DNA via Ca2+ ions. Also, serum protein could interact with the poly(MPC) brush via DNA, although the brush itself hardly interacted with serum proteins. Cell adhesion was significantly provoked on poly(MPC)/DNA compared with poly(MPC) because serum protein adsorption was induced on poly(MPC)/DNA.

  • 40.
    Bagheri, Narjes
    et al.
    Mat & Energy Res Ctr, Div Ceram, POB 31787-316, Karaj, Iran..
    Aghaei, Alireza
    Mat & Energy Res Ctr, Div Ceram, POB 31787-316, Karaj, Iran..
    Vlachopoulos, Nick
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Skunik-Nuckowska, Magdalena
    Univ Warsaw, Fac Chem, Pasteura 1, PL-02093 Warsaw, Poland..
    Kulesza, Pawel J.
    Univ Warsaw, Fac Chem, Pasteura 1, PL-02093 Warsaw, Poland..
    Häggman, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Univ Paris 07, Sorbonne Paris Cite, CNRS, UMR 7086,ITODYS, 15 Rue Jean Antoinede Baif, F-75205 Paris 13, France.;Sungkyankwan Univ, Sch Chem Engn, Suwon 440746, South Korea..
    Physicochemical identity and charge storage properties of battery-type nickel oxide material and its composites with activated carbon2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 194, p. 480-488Article in journal (Refereed)
    Abstract [en]

    The structural properties of annealed nickel oxide and its composites with activated carbon (synthesized via simple precipitation methods) have been addressed using X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption/desorption method and scanning electron microscopy. The charge storage properties of materials have also been investigated in three-and two-electrode configurations by means of cyclic voltammetry and galvanostatic charging/discharging in alkaline media. The results are consistent with the view that, depending on a method of preparation, the resulting nickel oxide films may exhibit redox characteristics different from that typically observed for nickel oxide-based materials. It is demonstrated that faradaic-type (redox) reactions, that are typical for battery-like materials, contribute predominantly to the high electrode capacity of 257C g(-1) (at 0.1 A g(-1)). By combining nickel oxide with a capacitive material such as activated carbon within the two-electrode symmetric cell, systems with increased charge-storage capabilities have been obtained. The fact, that the voltage window of nickel oxide-based cell has been broadened positively from 0.6 V to 1 V upon introduction of activated carbon, has also resulted in the increase of the cell's energy and power densities as well. 

  • 41.
    Banerjee, Amitava
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Araujo, Rafael Barros
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sjödin, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Appl Mat Phys, Dept Mat, S-10044 Stockholm, Sweden;Royal Inst Technol KTH, Appl Mat Phys, Dept Engn, S-10044 Stockholm, Sweden.
    Identifying the tuning key of disproportionation redox reaction in terephthalate: A Li-based anode for sustainable organic batteries2018In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 47, p. 301-308Article in journal (Refereed)
    Abstract [en]

    The ever-increasing consumption of energy storage devices has pushed the scientific community to realize strategies toward organic electrodes with superior properties. This is owed to advantages such as economic viability and eco-friendliness. In this context, the family of conjugated dicarboxylates has emerged as an interesting candidate for the application as negative electrodes in advanced Li-ion batteries due to the revealed thermal stability, rate capability, high capacity and high cyclability. This work aims to rationalize the effects of small molecular modifications on the electrochemical properties of the terephthalate anode by means of first principles calculations. The crystal structure prediction of the investigated host compounds dilithium terephthalate (Li2TP) and diethyl terephthalate (Et2Li0TP) together with their crystal modification upon battery cycling enable us to calculate the potential profile of these materials. Distinct underlying mechanisms of the redox reactions were obtained where Li2TP comes with a disproportionation reaction while Et2Li0TP displays sequential redox reactions. This effect proved to be strongly correlated to the Li coordination number evolution upon the Li insertion into the host structures. Finally, the calculations of sublimation enthalpy inferred that polymerization techniques could easily be employed in Et2Li0TP as compared to Li2TP. Similar results are observed with methyl, propyl, and vinyl capped groups. That could be a strategy to enhance the properties of this compound placing it into the gallery of the new anode materials for state of art Li-batteries.

  • 42.
    Barankova, Hana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bardos, Ladislav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Pulsed Atmospheric Pressure Plasma Reforming Of Ethanol2016In: Hakone XV: International Symposium On High Pressure Low Temperature Plasma Chemistry: With Joint Cost TD1208 Workshop: Non-Equilibrium Plasmas With Liquids For Water And Surface Treatment / [ed] Cernak, M; Hoder, T, 2016, p. 380-381Conference paper (Refereed)
    Abstract [en]

    The plasma source with a coaxial geometry was used for generation of plasma inside water and the ethanol-water mixtures. The hydrogen-rich synthesis gas with hydrogen content up to 60% was produced in submerged dc pulsed plasma. The effect of various plasma generation regimes on the performance of plasma, on the hydrogen production efficiency and on the reaction rise-time was examined. A role of the solution temperature, composition of the mixture and current delivered to the discharge are investigated.

  • 43. Barrabes, Noelia
    et al.
    Foettinger, Karin
    Llorca, Jordi
    Dalinov, Anton
    Medina, Francesc
    Sa, Jacinto
    Hardacre, Christopher
    Rupprechter, Guenther
    Pretreatment Effect on Pt/CeO2 Catalyst in the Selective Hydrodechlorination of Trichloroethylene2010In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, no 41, p. 17675-17682Article in journal (Refereed)
  • 44. Barrabes, Noelia
    et al.
    Sa, Jacinto
    Catalytic nitrate removal from water, past, present and future perspectives2011In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 104, no 1-2, p. 1-5Article in journal (Refereed)
  • 45.
    Barreleiro, P C A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Olofsson, G
    Brown, W
    Edwards, K
    Bonassi, N M
    Feitosa, E
    Interaction of Octaethylene Glycol n-Dodecyl Monoether with Dioctadecyldimethylammonium Bromide and Chloride Vesicles2002In: Langmuir, Vol. 18, p. 1024-1029Article in journal (Refereed)
  • 46.
    Bauer, Christophe
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Mukhtar, Emad
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Interfacial Elevtron-Transfer Dynamics in Ru(tcterpy)(NCS)3-Sensiitized TiO2 Nanocrystalline Solar Cells2002In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 106, p. 12693-12704Article in journal (Refereed)
    Abstract [en]

    The anchoring of the ruthenium dye {(C4H9)4N}[Ru(Htcterpy)(NCS)3] (with tcterpy = 4,4‘,4‘‘-tricarboxy-2,2‘:6‘,2‘‘-terpyridine), the so-called black dye, onto nanocrystalline TiO2 films has been characterized by UV−vis and FT-IR spectroscopies. FT-IR spectroscopy data suggest that dye molecules are bound to the surface by a bidentate binuclear coordination mode. The interfacial electron-transfer (ET) dynamics has been investigated by femtosecond pump−probe transient absorption spectroscopy and nanosecond laser flash photolysis. The electron-injection process from the dye excited state into the TiO2 conduction band is biexponential with a fast component (200 ± 50 fs) and a slow component (20 ps). These two components can be attributed to the electron injection from the initially formed and the relaxed dye excited states, respectively. Nanosecond kinetic data suggest the existence of two distinguishable regimes (I and II) for the rates of reactions between injected electrons and oxidized dye molecules or oxidized redox species (D+ or I2•-). The frontier between these two regimes is defined by the number of injected electrons per particle (Ne), which was determined to be about 1. The present kinetic study was undertaken within regime I (Ne > 1). Under these conditions, the back-electron-transfer kinetics is comparable to that in systems with other ruthenium complexes adsorbed onto TiO2. The reduction of oxidized dye molecules by iodide results in the formation of I2•- on a very fast time scale (<20 ns). Within regime I, the decay of I2•- occurs in 100 ns via reaction with injected electrons (I2•- + e- → 2I-). In regime II (Ne ≤ 1), which corresponds to the normal operating conditions of dye-sensitized solar cells, the decay of I2•- is very slow and likely occurs via the dismutation reaction (2I2•-→ I- + I3-). Our results predict that, under high light intensity (Ne > 1), the quantum efficiency losses in dye-sensitized solar cells will be important because of the dramatic acceleration of the reaction between I2•- and injected electrons. Mechanisms for the ET reactions involving injected electrons are proposed. The relevance of the present kinetic studies for dye-sensitized nanocrystalline solar cells is discussed.

  • 47.
    Beermann, Niclas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Trapping of electrons in nanostructured TiO2 studied by photocurrent transients2002In: Journal of Photochemistry and Photobiology A: Chemistry, Vol. 152, p. 213-218Article in journal (Refereed)
  • 48.
    Behrouznejad, F.
    et al.
    Sharif Univ Technol, Inst Nanosci & Nanotechnol, Tehran 14588, Iran..
    Taghavinia, N.
    Sharif Univ Technol, Inst Nanosci & Nanotechnol, Tehran 14588, Iran.;Sharif Univ Technol, Dept Phys, Tehran 14588, Iran..
    Pazoki, Meysam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tajabadi, F.
    Mat & Energy Res Ctr, Nanotechnol & Adv Mat Dept, Karaj 31787316, Iran..
    Metal-based bracken-like single-sided dye-sensitized solar cells with horizontal separation2016In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 7, p. 5244-5252Article in journal (Refereed)
    Abstract [en]

    One of the drawbacks of typical dye-sensitized solar cells (DSCs) is their high cost and the high electrical resistance of the transparent conducting substrate. In conventional sandwich-type DSCs, only one of the FTO substrates can be replaced by a metal substrate. We investigated an all-metal-electrode single-sided DSC in which interpenetrated bracken-like Cr electrodes were created using photolithography; mesoporous TiO2 and Pt films were deposited on the laterally separated electrodes. Thermal Pt deposition and electrodeposition methods were investigated and it was found that a cyclic electrodeposition method resulted in selective Pt deposition at room temperature with a higher device performance. Cu or ZnO sacrificial layers and TiO2 or TiO2/SiO2 porous layers were used for the spacer layer that keeps the Pt electrode away from the TiO2 mesoporous layer and the optimum results were obtained when a TiO2/SiO2 layer was used. The best device had a current density of 8.47 mA cm(-2), an open circuit voltage of 0.685 V and an efficiency of 2.44%. The results of open circuit voltage decay and electrochemical impedance spectrometry showed the formation of a high-resistivity blocking layer, which was attributed to the Cr oxide formed during thermal treatment. The efficiency may be improved further by developing low-temperature fabrication processes.

  • 49.
    Behzadi, Hadi
    et al.
    Kharazmi Univ, Fac Chem, Dept Phys Chem, Tehran, Iran.
    Roonasi, Payman
    Kharazmi Univ, Fac Chem, Dept Phys Chem, Tehran, Iran.
    Taghipour, Khatoon Assle
    Kharazmi Univ, Fac Chem, Dept Phys Chem, Tehran, Iran.
    van der Spoel, David
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Manzetti, Sergio
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational Biology and Bioinformatics. Fjordforsk AS Inst Sci & Technol, N-6894 Midtun, Vangsnes, Norway.
    Relationship between electronic properties and drug activity of seven quinoxaline compounds: A DFT study2015In: Journal of Molecular Structure, ISSN 0022-2860, E-ISSN 1872-8014, Vol. 1091, p. 196-202Article in journal (Refereed)
    Abstract [en]

    The quantum chemical calculations at the DFT/B3LYP level of theory were carried out on seven quinoxaline compounds, which have been synthesized as anti-Mycobacterium tuberculosis agents. Three conformers were optimized for each compound and the lowest energy structure was found and used in further calculations. The electronic properties including E-HOMO, E-LUMO and related parameters as well as electron density around oxygen and nitrogen atoms were calculated for each compound. The relationship between the calculated electronic parameters and biological activity of the studied compounds were investigated. Six similar quinoxaline derivatives with possible more drug activity were suggested based on the calculated electronic descriptors. A mechanism was proposed and discussed based on the calculated electronic parameters and bond dissociation energies.

  • 50. Beinik, Igor
    et al.
    Hellström, Matti
    Jensen, Thomas
    Broqvist, Peter
    Lauritsen, Jeppe
    Cu wets the polar ZnO(0001)-Zn surface because of interaction with subsurface defectsArticle in journal (Refereed)
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