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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.2012Inngår i: Chimia (Basel), ISSN 0009-4293, Vol. 66, nr 9, 699-705 s.Artikkel i tidsskrift (Fagfellevurdert)
    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.
    Abrahamsson, Malin L. A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Berglund Baudin, Helena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Tran, A.
    Philouze, C.
    Berg, K.
    Raymond-Johansson, Mary Katherine
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Sun, L.
    Åkermark, B.
    Styring, S.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Ruthenium-Manganese Complexes for Artificial Photosynthesis: Factors Controlling Intramolecular Electron Transfer and Excited State Quenching Reactions2002Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 41, nr 6, 1534-1544 s.Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 3.
    Abramavicius, V.
    et al.
    Vilnius University, Lithuania; Centre Phys Science and Technology, Lithuania.
    Pranculis, V.
    Centre Phys Science and Technology, Lithuania.
    Melianas, Armantas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Inganäs, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biomolekylär och Organisk Elektronik. Linköpings universitet, Tekniska fakulteten.
    Gulbinas, V.
    Centre Phys Science and Technology, Lithuania.
    Abramavicius, D.
    Vilnius University, Lithuania.
    Role of coherence and delocalization in photo-induced electron transfer at organic interfaces2016Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, nr 32914Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photo-induced charge transfer at molecular heterojunctions has gained particular interest due to the development of organic solar cells (OSC) based on blends of electron donating and accepting materials. While charge transfer between donor and acceptor molecules can be described by Marcus theory, additional carrier delocalization and coherent propagation might play the dominant role. Here, we describe ultrafast charge separation at the interface of a conjugated polymer and an aggregate of the fullerene derivative PCBM using the stochastic Schrodinger equation (SSE) and reveal the complex time evolution of electron transfer, mediated by electronic coherence and delocalization. By fitting the model to ultrafast charge separation experiments, we estimate the extent of electron delocalization and establish the transition from coherent electron propagation to incoherent hopping. Our results indicate that even a relatively weak coupling between PCBM molecules is sufficient to facilitate electron delocalization and efficient charge separation at organic interfaces.

  • 4.
    Adam, Stefan
    et al.
    Leibniz Institute Polymerforsch eV, Germany; Technical University of Dresden, Germany.
    Koenig, Meike
    Leibniz Institute Polymerforsch eV, Germany; Technical University of Dresden, Germany; Karlsruhe Institute Technology, Germany.
    Rodenhausen, Keith Brian
    University of Nebraska, NE 68588 USA; Biolin Science Inc, NJ 07652 USA.
    Eichhorn, Klaus-Jochen
    Leibniz Institute Polymerforsch eV, Germany.
    Oertel, Ulrich
    Leibniz Institute Polymerforsch eV, Germany.
    Schubert, Mathias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Leibniz Institute Polymerforsch eV, Germany; University of Nebraska, NE 68588 USA; University of Nebraska, NE 68588 USA.
    Stamm, Manfred
    Leibniz Institute Polymerforsch eV, Germany; Technical University of Dresden, Germany.
    Uhlmann, Petra
    Leibniz Institute Polymerforsch eV, Germany; University of Nebraska, NE 68588 USA.
    Quartz crystal microbalance with coupled Spectroscopic Ellipsometry-study of temperature-responsive polymer brush systems2017Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, 843-851 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using a combined setup of quartz crystal microbalance with dissipation monitoring together with spectroscopic ellipsometry, the thermo-responsive behavior of two different brush systems (poly(N-isopropyl acrylamide) and poly(2-oxazoline)s) was investigated and compared to the behavior of the free polymer in solution. Poly(2-oxazoline)s with three different hydrophilicities were prepared by changing the content of a hydrophilic comonomer. While both polymer types exhibit a sharp, discontinuous thermal transition in solution, in the brush state the transition gets broader in the case of poly(N-isopropyl acrylamide) and is transformed into a continuous transition for poly(2-oxazoline)s. The position of the transition in solution is influenced by the degree of hydrophilicity of the poly(2-oxazoline). The difference in areal mass detected by quartz crystal microbalance and by spectroscopic ellipsometry, has been attributed to the chain segment density profile of the polymer brushes. Applying this density profile information, for poly(N-isopropyl acrylamide) two different swelling stages could be identified, while for poly(2-oxazoline) the transition between a parabolic and more step-wise profile is found continuous. The different swelling characteristics were attributed to the different miscibility behavior types, with the brush state acting similar to a crosslinked system. (C) 2017 Elsevier B.V. All rights reserved.

  • 5. Adamska-Venkatesh, Agnieszka
    et al.
    Mirmohades, Mohammad
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Sommer, Constanze
    Reijerse, Edward
    Lubitz, Wolfgang
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Following [FeFe] Hydrogenase Active Site Intermediates by Flash Photolysis/Mid-IR ProbingManuskript (preprint) (Annet vitenskapelig)
  • 6.
    Adhikari, Arindam
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Claesson, Per M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Pani, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Deidinaitei, Andra
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Blomberg, Eva
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Electrochemical behavior and anticorrosion properties of modified polyaniline dispersed in polyvinylacetate coating on carbon steel2008Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 0019-4686, Vol. 53, nr 12, 4239-4247 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Conducting polyaniline (Pani) was prepared in the presence of methane sulfonic acid (MeSA) as dopant by chemical oxidative polymerization. The Pani-MeSA polymer was characterized by FT-IR, UV-vis, X-ray diffraction (XRD) and impedance spectroscopy. The polyrner was dispersed in polyvinylacetate and coated oil carbon steel samples by a dipping method. The electrochemical behavior and anticorrosion properties of the coating, oil carbon steel in 3% NaCl were investigated using Open-circuit Potential (OCP) versus time of exposure, and electrochemical techniques including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and cyclic voltammetry (CV). During initial exposure, the OCP dropped about 0.35 V and the interfacial resistance increased several times, indicating I certain reduction of the polymer and oxidation of the steel surface. Later the OCP shifted to the noble direction and remained at a stable value during the exposure up to 60 days. The EIS monitoring also revealed the initial change and later stabilization of the coating. The stable high OCP and low coating impedance Suggest that the conducting polymer maintains its oxidative state and provides corrosion protection for carbon steel through out the investigated period. The polarization curves and CV show that the conducting polymer coating induces a passive-like behavior and greatly reduces the corrosion of carbon steel.

  • 7.
    Agmo Hernandez, Victor
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi.
    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 mechanism2009Inngår i: Journal of Solid State Electrochemistry, ISSN 1432-8488, E-ISSN 1433-0768, Vol. 13, nr 4, 639-649 s.Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 8.
    Agmo Hernández, Víctor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    The theory of metal electronucleation applied to the study of fundamental properties of liposomes2013Inngår i: Journal of Solid State Electrochemistry, ISSN 1432-8488, E-ISSN 1433-0768, Vol. 17, nr 2 (SI), 299-305 s.Artikkel, forskningsoversikt (Fagfellevurdert)
    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.

  • 9.
    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 electrodes2008Inngår i: Bioelectrochemistry, ISSN 1567-5394, E-ISSN 1878-562X, Vol. 74, nr 1, 149-156 s.Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 10. Ahlgren, Sara
    et al.
    Reijmar, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Edwards, Katarina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    EGF-targeting lipodisks for specific delivery of cationic amphiphilic peptides to tumour cellsManuskript (preprint) (Annet vitenskapelig)
  • 11. Ahlgren, Sara
    et al.
    Reijmar, Karin
    Edwards, Katarina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Targeting lipodisks enable selective delivery of anticancer peptides to tumor cells.2017Inngår i: Nanomedicine: Nanotechnology, Biology and Medicine, ISSN 1549-9634, E-ISSN 1549-9642, Vol. 13, nr 7, 2325-2328 s., S1549-9634(17)30130-2Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 12.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    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 Calculations2017Inngår i: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 121, nr 13, 2643-2654 s.Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 13.
    Ahlstrand, Emma
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för kemi och biomedicin (KOB).
    Hermansson, Kersti
    Uppsala University.
    Friedman, Ran
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för kemi och biomedicin (KOB).
    Interaction Energies in Complexes of Zn and Amino Acids: A Comparison of Ab Initio and Force Field Based Calculations2017Inngår i: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 121, nr 13, 2643-2654 s.Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 14.
    Ahlström, Peter
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Aim, Karel
    Dohrn, Ralf
    Elliott, J. Richard
    Jackson, George
    Jaubert, Jean-Noel
    Rebello de A. Macedo, Maria Eugénia
    Pokki, Juha-Pekka
    Reczey, Kati
    Victorov, Alexey
    Fele Zilnik, Ljudmila
    Economou, Ioannis
    A Survey of Thermodynamics and Transport Properties in Chemical Engineering Education in Europe and the USA2008Inngår i: Proceedings of the 100th Annual Meeting of the American Institute for Chemical Engineering, 2008Konferansepaper (Fagfellevurdert)
  • 15.
    Ahlström, Peter
    et al.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Moodley, Suren
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Bolton, Kim
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Ramjugernath, D.
    Högskolan i Borås, Institutionen Ingenjörshögskolan.
    Computer Simulations of Vapor-Liquid-Liquid Equilibria Involving Hydrocarbons and Water2008Inngår i: Proceedings of the 100th Annual Meeting of the American Institute for Chemical Engineering, 2008, CHPC National Meeting, Durban, South Africa, December 9-10, 2008, AlChe Annual Meeting, Philadelphia, November 15-21, 2008, 2008Konferansepaper (Annet vitenskapelig)
  • 16.
    Ahmed, Hamzah
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Shimpi, Manishkumar R.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Velaga, Sitaram P.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Relationship between mechanical properties and crystal structure in cocrystals and salt of paracetamol2017Inngår i: Drug Development and Industrial Pharmacy, ISSN 0363-9045, E-ISSN 1520-5762, Vol. 43, nr 1, 89-97 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objectives were to study mechanical properties of various solid forms of paracetamol and relate to their crystal structures. Paracetamol Form I (PRA), its cocrystals with oxalic acid (PRA-OXA) and 4,4-bipyridine (PRA-BPY) and hydrochloride salt (PRA-HCL) were selected. Cocrystals and salt were scaled-up using rational crystallization methods. The resulting materials were subjected to differential scanning solid-state characterization. The powders were sieved and 90-360 µm sieve fraction was considered. These powders were examined by scanning electron microscopy (SEM) and densities were determined. Tablets were made at applied pressures of 35-180 MPa under controlled conditions and the tablet height, diameter and hardness were measured. Tensile strength and porosity of the tablets were estimated using well known models. Crystal structures of these systems were visualized and slips planed were identified. Cocrystal and salt of PRA were physically pure. Sieved powders had comparable morphologies and particle size. The apparent and theoretical densities of powders were similar but no clear trends were observed. The tensile strengths of these compacts were increased with increasing pressure whereas tabletability decreased in the order oxalic acid > PRA-HCL ≈ PRA-OXA > BPY > PRA-BPY. Tablet tensile strength decreases exponentially with increasing porosity with the exception of PRY-BPY and BPY. Slip plane prediction based on attachment energies may not be independently considered. However, it was possible to explain the improved mechanical properties of powders based on the crystal structure. Cocrystallization and salt formation have introduced structural features that are responsible for improved tableting properties of PRA.

  • 17. Ahmed, Towfiq
    et al.
    Haraldsen, Jason T.
    Zhu, Jian-Xin
    Balatsky, Alexander V.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. Institute for Materials Science, Los Alamos National Laboratory, United States.
    Next-Generation Epigenetic Detection Technique: Identifying Methylated Cytosine Using Graphene Nanopore2014Inngår i: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 5, nr 15, 2601-2607 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    DNA methylation plays a pivotal role in the genetic evolution of both embryonic and adult cells. For adult somatic cells, the location and dynamics of methylation have been very precisely pinned down with the 5-cytosine markers on cytosine-phosphate-guanine (CpG) units. Unusual methylation on CpG islands is identified as one of the prime causes for silencing the tumor suppressant genes. Early detection of methylation changes can diagnose the potentially harmful oncogenic evolution of cells and provide promising guideline for cancer prevention. With this motivation, we propose a cytosine methylation detection technique. Our hypothesis is that electronic signatures of DNA acquired as a molecule translocates through a nanopore would be significantly different for methylated and nonmethylated bases. This difference in electronic fingerprints would allow for reliable real-time differentiation of methylated DNA. We calculate transport currents through a punctured graphene membrane while the cytosine and methylated cytosine translocate through the nanopore. We also calculate the transport properties for uracil and cyanocytosine for comparison. Our calculations of transmission, current, and tunneling conductance show distinct signatures in their spectrum for each molecular type. Thus, in this work, we provide a theoretical analysis that points to a viability of our hypothesis.

  • 18. Ai, Yuejie
    et al.
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ji, Yongfei
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Song, Wei-Guo
    Luo, Yi
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Hydrophobicity and Hydrophilicity Balance Determines Shape Selectivity of Suzuki Coupling Reactions Inside Pd@meso-SiO2 Nanoreactor2016Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, nr 19, 10244-10251 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Molecular sorting and catalysis directed by shape selectivity have been extensively applied in porous extended frameworks for a low-carbon, predictable, renewable component of modern industry. A comprehensive understanding of the underlying recognition mechanism toward different shapes is unfortunately still missing, owing to the lack of structural and dynamic information under operating conditions. We demonstrate here that such difficulties can be overcome by state-of-the-art molecular dynamics simulations which provide atomistic details that are not accessible experimentally, as exemplified by our interpretation for the experimentally observed aggregation induced shape selectivity for Suzuki C-C coupling reaction catalyzed by Pd particles in mesoporous silica. It is found that both aggregation ability and aggregating pattern of the reactants play the decisive role in controlling the shape selectivity, which are in turn determined by the balance between the hydrophobicity and hydrophilicity of the reactants, or in other words, by the balance between the noncovalent hydrogen bonding interaction and van der Waals forces. A general rule that allows prediction of the shape selectivity of a reactant has been proposed and verified against experiments. We show that molecular modeling is a powerful tool for rational design of new mesoporous systems and for the control of catalytic reactions that are important for the petrochemical industry.

  • 19. Ai, Yue-jie
    et al.
    Tian, Guangjun
    Liao, Rong-zhen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhang, Qiong
    Fang, Wei-hai
    Luo, Yi
    Intrinsic Property of Flavin Mononucleotide Controls its Optical Spectra in Three Redox States2011Inngår i: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 12, nr 16, 2899-2902 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 20. Aidas, Kestutis
    et al.
    Agren, Hans
    Kongsted, Jacob
    Laaksonen, Aatto
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för tillämpad miljövetenskap (ITM).
    Mocci, Francesca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    A quantum mechanics/molecular dynamics study of electric field gradient fluctuations in the liquid phase. the case of na+ in aqueous solution2013Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, nr 5, 1621-1631 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Na-23 quadrupolar coupling constant of the Na+ ion in aqueous solution has been predicted using molecular dynamics simulations and hybrid quantum mechanics/molecular mechanics methods for the calculation of electric field gradients. The developed computational approach is generally expected to provide reliable estimates of the quadrupolar coupling constants of monoatomic species in condensed phases, and we show here that intermolecular polarization and non-electrostatic interactions are of crucial importance as they result in a 100% increased quadrupolar coupling constant of the ion as compared to a simpler pure electrostatic picture. These findings question the reliability of the commonly applied classical Sternheimer approximation for the calculations of the electric field gradient. As it can be expected from symmetry considerations, the quadrupolar coupling constants of the 5- and 6-coordinated Na+ ions in solution are found to differ significantly.

  • 21.
    Aidas, Kestutis
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Kongsted, Jacob
    Laaksonen, Aatto
    Mocci, Francesca
    A quantum mechanics/molecular dynamics study of electric field gradient fluctuations in the liquid phase. The case of Na+ in aqueous solution2013Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, nr 5, 1621-1631 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Na-23 quadrupolar coupling constant of the Na+ ion in aqueous solution has been predicted using molecular dynamics simulations and hybrid quantum mechanics/molecular mechanics methods for the calculation of electric field gradients. The developed computational approach is generally expected to provide reliable estimates of the quadrupolar coupling constants of monoatomic species in condensed phases, and we show here that intermolecular polarization and non-electrostatic interactions are of crucial importance as they result in a 100% increased quadrupolar coupling constant of the ion as compared to a simpler pure electrostatic picture. These findings question the reliability of the commonly applied classical Sternheimer approximation for the calculations of the electric field gradient. As it can be expected from symmetry considerations, the quadrupolar coupling constants of the 5- and 6-coordinated Na+ ions in solution are found to differ significantly.

  • 22.
    Aitola, Kerttu
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    High Temperature-Stable Perovskite Solar Cell Based on Low-Cost Carbon Nanotube Hole Contact2017Inngår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 29, nr 17, 1606398Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 23.
    Aitola, Kerttu
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Sveinbjörnsson, Kári
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. 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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Carbon nanotube-based hybrid hole-transporting material and selective contact for high efficiency perovskite solar cells2016Inngår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 9, nr 2, 461-466 s.Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 24.
    Aitola, Kerttu
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Zhang, Jinbao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Carbon nanotube film replacing silver in high-efficiency solid-state dye solar cells employing polymer hole conductor2015Inngår i: Journal of Solid State Electrochemistry, ISSN 1432-8488, E-ISSN 1433-0768, Vol. 19, nr 10, 3139-3144 s.Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 25. 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 conductor2015Inngår i: Journal of Solid State ElectrochemistryArtikkel i tidsskrift (Fagfellevurdert)
    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.

  • 26. Ai-Xi, Chen
    et al.
    Hong, Wang
    Duan, Sai
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Hai-Ming, Zhang
    Xin, Xu
    Li-Feng, Chi
    Potential-Induced Phase Transition of N-Isobutyryl-L-cysteine Monolayers on Au(111) Surfaces2017Inngår i: Wuli huaxue xuebao, ISSN 1000-6818, Vol. 33, nr 5, 1010-1016 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Functional solid substrates modified by self-assembled monolayers (SAMs) have potential applications in biosensors, chromatography, and biocompatible materials. The potential-induced phase transition of N-isobutyryl-L-cysteine (L-NIBC) SAMs on Au(111) surfaces was investigated by in-situ electrochemical scanning tunneling microscopy (EC-STM) in 0.1 mol.L-1 H2SO4 solution. The NIBC SAMs with two distinct structures (alpha phase and beta phase) can be prepared by immersing the Au(111) substrate in pure NIBC aqueous solution and NIBC solution controlled by phosphate buffer at pH 7, respectively. The as-prepared a phase and beta phase of NIBC SAMs show various structural changes under the control of electrochemical potentials of the Au(111) in H2SO4 solution. The a phase NIBC SAMs exhibit structural changes from ordered to disordered structures with potential changes from 0.7 V (vs saturated calomel electrode, SCE) to 0.2 V. However, the beta phase NIBC SAMs undergo structural changes from disordered structures (E < 0.3 V) to y phase (0.4 V < E < 0.5 V) and finally to the beta phase (0.5 V < E < 0.7 V). EC-STM images also indicate that the phase transition from the alpha phase NIBC SAMs to the a phase occurs at positive potential. Combined with density functional theory (DFT) calculations, the phase transition from the beta phase to the a phase is explained by the potential-induced break of bonding interactions between -COO- and the negatively charged gold surfaces.

  • 27.
    Ajaikumar, Samikannu
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ahlkvist, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Larsson, William
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shchukarev, Andrey
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kordas, K
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Piispankatu 8, FIN-20500, Turku/Åbo, Finland.
    Oxidation of α-pinene over gold containing bimetallic nanoparticles supported on reducible TiO2 by DPU method2011Inngår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 392, nr 1-2, 11-18 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of bimetallic catalysts Au–M (where M = Cu, Co and Ru) were supported on a reducible TiO2 oxide via deposition-precipitation (DP) method with a slow decomposition of urea as the precipitating agent. The characteristic structural features of the prepared materials were characterized by various physico-chemical techniques such as X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). XPS results indicated the formation of alloyed bimetallic particles on the TiO2 support. TEM results confirmed the fine dispersion of metal nanoparticles on the support with an average particle size in the range of 3–5 nm. An industrially important process, oxy-functionalization of α-pinene was carried out over the prepared bimetallic heterogeneous catalysts under liquid phase conditions. Reaction parameters such as the reaction time, temperature, and the effect of solvent were studied for optimal conversion of α-pinene into verbenone. The major products obtained were verbenone, verbenol, α-pinene oxide and alkyl-pinene peroxide. The activity of the catalysts followed the order; AuCu/TiO2 > AuCo/TiO2 > Cu/TiO2 > Au/TiO2 > AuRu/TiO2. Upon comparison of the various catalysts, AuCu/TiO2 was found to be an active and selective catalyst towards the formation of verbenone. The temperature, nature of the catalysts and the choice of solvents greatly influenced the reaction rate.

  • 28.
    Akpe, Victor
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellens fysik.
    Brismar, Hjalmar
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellens fysik.
    Nyokong, Tebello
    Osadebe, P. O.
    Photophysical and photochemical parameters of octakis (benzylthio) phthalocyaninato zinc, aluminium and tin: Red shift index concept in solvent effect on the ground state absorption of zinc phthalocyanine derivatives2010Inngår i: Journal of Molecular Structure, ISSN 0022-2860, E-ISSN 1872-8014, Vol. 984, nr 1-3, 1-14 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper addresses the synthesis of octa-substituted benzylthio metallophthalocyanines (OBTMPcs) that contain the central metal ions of Zn2+, Al3+ and Sn4+. The ground state absorption of ZnPc(SR)(8) (OBTZnPc) along with the ZnPc derivatives, well documented in literature were used to study a new concept called the red shift index (RsI). The concept is based on the empirical values of RsI of the different complexes in solvent media. Unequivocally, parameters used in this paper show strong correlations that are consistent with the results obtained. For instance, 12,1 of the complexes tend to increase as the refractive index, n(D), and solvent donor, DN, of solvent increases. Photodegradation (photobleaching) quantum yield, phi(d) measurements of these compounds show that they are highly photostable, phi(d) (0.03-0.33 x 10(-5)). The triplet quantum yield, phi(T) (0.40-0.53) and the triplet lifetime, tau(T) (610-810 mu s) are within the typical range for metallophthalocyanines in DMSO. The photosensitisation efficiency. S-Delta, is relatively high for all the molecules (0.74-0.90). (C) 2010 Elsevier B.V. All rights reserved.

  • 29.
    Alaei, Zahra
    KTH, Skolan för kemivetenskap (CHE).
    Release of Solubilizate from Micelle Triggered by Core Freezing2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The present thesis focuses on the release of solubilizate from micelle triggered by core freezing studied using 1H-NMR spectroscopy. The surfactant studied was the nonionic BrijTM S20 with a concentration of 1 wt% in water and hexamethyldisiloxane (HMDSO) was used as the model solubilizate to be loaded in micelle. The solubilizate in the micelle was found be squeezed out by core shrinking of the micelle upon decreasing the temperature. Besides 1H-NMR spectra, self-diffusion coefficients and longitudinal relaxation times                          were also measured upon decreasing the temperature. The temperature-dependent fraction of HMDSO in the micelle was determined together with relevant properties of the micelle, such as core freezing point, internal dynamics and size. The results were compared to corresponding data in the neat micellar system.

  • 30.
    Alami, E
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Almgren, Mats
    Brown, Wyn
    Francois, Jeanette
    Aggregation of hydrophobically end-capped poly(ethylene oxide) in aqueous solutions. Fluorescence and light-scattering studies1996Inngår i: MACROMOLECULES, Vol. 29, nr 6, 2229-2243 s.Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 31.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    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 waters2016Inngår i: Chemical Engineering and Processing, ISSN 0255-2701, E-ISSN 1873-3204, Vol. 108, 58-73 s.Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 32.
    Aldener, Mattias
    Stockholms universitet.
    Pulsed laser experiments in chemical physics2001Doktoravhandling, med artikler (Annet vitenskapelig)
  • 33.
    Aleckovic, Ehlimana
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Andersson, Linnea
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Chamoun, Sherley
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Einarsson, Ellen
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Ekstedt, Ebba
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Eriksen, Emma
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Madan-Andersson, Maria
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Method Development for Determining the Stability of Heat Stable Proteins Combined with Biophysical Characterization of Human Calmodulin and the Disease Associated Variant D130G2016Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Calmodulin is a highly conserved calcium ion binding protein expressed in all eukaryotic species. The 149 amino acid residues in the primary structure are organized in seven α helices with the highly flexible central α helix connecting the two non-cooperative domains of calmodulin. Each domain contains two EF-hand motifs to which calcium ions bind in a cooperative manner, hence the binding of four calcium ions saturate one calmodulin molecule. In the cardiovascular area calmodulin is involved in the activation of cardiac muscle contraction, and mutations that arise in the genetic sequence of the protein often have severe consequences. One such consequential mutation that can arise brings about the replacement of the highly conserved aspartic acid with glycine at position 130 in the amino acid sequence. In this research, the thermal and chemical stability within the C domain of the D130G variant of human calmodulin was investigated using a new method only requiring circular dichroism spectroscopic measurements. Affinity studies within the C domain of the D130G variant of human calmodulin were performed using fluorescence spectroscopy, and the ligands chosen for this purpose were trifluoperazine and p- HTMI. All analytical experiments were performed with the C domain of wild type human calmodulin as a reference. From the new method, it was concluded that the C domain of the D130G variant of human calmodulin has a slightly decreased stability in terms of Tm and Cm values compared to the C domain of wild type human calmodulin. The affinity analyses indicated that neither trifluoperazine nor p-HTMI discriminates between the C domain of the D130G variant of human calmodulin and the C domain of wild type human calmodulin in terms of dissociation constants. The pivotal outcome from this research is that the new method is applicable for determination of the stability parameters Tm and Cm of heat stable proteins. 

  • 34.
    Alexander, Shovsky
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Polyelectrolyte complexes of bottle brush copolymers: Solution and adsorption properties2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The aim of this thesis work was to systematically investigate the physico-chemical properties of polyelectrolyte complexes (PECs) formed by bottle brush and linear polyelectrolytes in solution and at solid / liquid interfaces. Electrostatic self-assembly of oppositely charged macromolecules in aqueous solution is a versatile strategy to construction of functional nanostructures with easily controlled properties. Bottle brush architecture, introduced into the PEC, generates a number of distinctive properties of the complexes, related to a broad range of application, such as colloidal stability and protein repellency to name a few. To utilize these materials in a wide range of applications e.g. drug delivery, the understanding of the effects of polymer architecture and solution parameters on the properties of bottle brush PECs is of paramount importance. This thesis constitutes a systematic investigation of PECs formed by a series of cationic bottle-brush polyelectrolytes and a series of anionic linear polyelectrolytes in aqueous solution. The focus of the first part of the thesis was primarily on formation and characterization of PECs in solution, whereas the adsorption properties and adsorption kinetics of bottle-brush polyelectrolytes and their complexes was investigated in the second part of the thesis work. In particular, effects of the side-chain density of the bottlebrush polyelectrolyte, concentration, mixing ratio and molecular weigh of the linearpolyelectrolyte on formation, solution properties, stability and adsorption of PECs were addressed.

    The pronounced effect of the side-chain density of the bottle-brush polyelectrolyte on the properties of stoichiometric and nonstoichiometric PECs was demonstrated. Formation of PECs by bottle-brush copolymers with high density of side-chains results in small, watersoluble, molecular complexes having nonspherical shape, independent of concentration. Whereas formation of PEC-aggregates was revealed by bottle-brush polyelectrolytes with low side chain density, the level of aggregation in these complexes is controlled by polyelectrolyte concentration. The structure of the PECs formed with low molecular weight polyanions is consistent with the picture that several small linear polyelectrolyte molecules associate with the large bottle-brush. In contrast, when complexation occurs between polyanions of high molecular weigh and the bottle-brush polymers considerably larger PECs are formed, consistent with several bottle-brush polymers associating with one high molecular weight polyanion.

  • 35. Allouche, Joachim
    et al.
    Tyrode, Eric
    Laboratorio FIRP, Ingeniería Química, Universidad de Los Andes, Avenida Don Tulio Febres, Mérida .
    Sadtler, Veronique
    Choplin, Lionel
    Salager, Jean-Louis
    Simultaneous Conductivity and Viscosity Measurements as a Technique To Track Emulsion Inversion by the Phase-Inversion-Temperature Method2004Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 20, nr 6, 2134-2140 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two kinds of transitions can occur when an emulsified water-oil-ethoxylated nonionic surfactant system is cooled under const. stirring. At a water-oil ratio close to unity, a transitional inversion takes place from a water-in-oil (W/O) to an oil-in-water (O/W) morphol. according to the so-called phase-inversion-temp. method. At a high water content, a multiple W/O/W emulsion changes to a simple O/W emulsion. The continuous monitoring of both the emulsion cond. and viscosity allows the identification of several phenomena that take place during the temp. decrease. In all cases, a viscosity max. is found on each side of the three-phase behavior temp. interval and correlates with the attainment of extremely fine emulsions, where the best compromise between a low-tension and a not-too-unstable emulsion is reached. The studied system contains Polysorbate 85, a light alkane cut oil, and a sodium chloride brine. All transitions are interpreted in the framework of the formulation-compn. bidimensional map.

  • 36. Allouche, Joachim
    et al.
    Tyrode, Eric
    FIRP Laboratory, Universidad de Los Andes, Mérida.
    Sadtler, Veronique
    Choplin, Lionel
    Salager, Jean-Louis
    Single- and Two-Step Emulsification To Prepare a Persistent Multiple Emulsion with a Surfactant-Polymer Mixture2003Inngår i: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 42, nr 17, 3982-3988 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The regions corresponding to different emulsion morphol. occurrences have been clearly identified on a bidimensional formulation-compn. map. Multiple emulsions spontaneously form when there is a conflict between the formulation and compn. effects. In such systems the most external emulsion is found to be unstable when the formulation effect is produced by a single surfactant. The use of a proper surfactant-polymer mixt. allows one to strongly inhibit the mass transfer and to considerably lengthen the equilibration between interfaces. As a consequence, the multiple emulsion can be stable enough to be used in encapsulation and controlled-release applications. The area where multiple emulsions occur and their characteristics (cond. and amt. of encapsulated external phase) are reported for a system contg. a sorbitan ester lipophilic surfactant and a diblock poly(ethylene oxide)-poly(propylene oxide) hydrophilic polymer, as a function of the formulation and compn., for a single-step process in which a specific amt. of mech. energy (stirring) is supplied. An increase in the oil viscosity is found to alter the map and to modify the multiple emulsion characteristics. The application of the results to emulsion-making technol. is discussed.

  • 37.
    Almgren, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Fysikalisk kemi.
    Stomatosomes: perforated bilayer structures2010Inngår i: Soft Matter, ISSN 1744-683X, Vol. 6, nr 7, 1383-1390 s.Artikkel, forskningsoversikt (Fagfellevurdert)
    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.

  • 38. Alonso-Mori, R.
    et al.
    Asa, K.
    Bergmann, U.
    Brewster, A. S.
    Chatterjee, R.
    Cooper, J. K.
    Frei, H. M.
    Fuller, F. D.
    Goggins, E.
    Gul, S.
    Fukuzawa, H.
    Iablonskyi, D.
    Ibrahim, M.
    Katayama, T.
    Kroll, T.
    Kumagai, Y.
    McClure, B. A.
    Messinger, Johannes
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Motomura, K.
    Nagaya, K.
    Nishiyama, T.
    Saracini, C.
    Sato, Y.
    Sauter, N. K.
    Sokaras, D.
    Takanashi, T.
    Togashi, T.
    Ueda, K.
    Weare, W. W.
    Weng, T-C
    Yabashi, M.
    Yachandra, V. K.
    Young, I. D.
    Zouni, A.
    Kern, J. F.
    Yano, J.
    Towards characterization of photo-excited electron transfer and catalysis in natural and artificial systems using XFELs2016Inngår i: Faraday discussions (Online), ISSN 1359-6640, E-ISSN 1364-5498, Vol. 194, 621-638 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ultra-bright femtosecond X-ray pulses provided by X-ray Free Electron Lasers (XFELs) open capabilities for studying the structure and dynamics of a wide variety of biological and inorganic systems beyond what is possible at synchrotron sources. Although the structure and chemistry at the catalytic sites have been studied intensively in both biological and inorganic systems, a full understanding of the atomic-scale chemistry requires new approaches beyond the steady state X-ray crystallography and X-ray spectroscopy at cryogenic temperatures. Following the dynamic changes in the geometric and electronic structure at ambient conditions, while overcoming X-ray damage to the redox active catalytic center, is key for deriving reaction mechanisms. Such studies become possible by using the intense and ultra-short femtosecond X-ray pulses from an XFEL, where sample is probed before it is damaged. We have developed methodology for simultaneously collecting X-ray diffraction data and X-ray emission spectra, using an energy dispersive spectrometer, at ambient conditions, and used this approach to study the room temperature structure and intermediate states of the photosynthetic water oxidizing metallo-protein, photosystem II. Moreover, we have also used this setup to simultaneously collect the X-ray emission spectra from multiple metals to follow the ultrafast dynamics of light-induced charge transfer between multiple metal sites. A Mn-Ti containing system was studied at an XFEL to demonstrate the efficacy and potential of this method.

  • 39. Altincekic, T. G.
    et al.
    Boz, I.
    Baykal, A.
    Kazan, S.
    Topkaya, R.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Synthesis and characterization of CuFe2O4 nanorods synthesized by polyol route2010Inngår i: Journal of Alloys and Compounds, ISSN 0925-8388, Vol. 493, nr 1-2, 493-498 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Uniform, high quality, CuFe2O4 nanorods with high aspect ratios were synthesized by a surfactant-free single step polyol process at 220 degrees C. The structure of the product was characterized by XRD and FT-IR, and the morphology of the product was analyzed by SEM. The results showed that the as-prepared nanorods have a uniform cross-section and with average diameter of similar to 100 nm and aspect ratio in the range of 13-52. X-ray line profile fitting resulted in crystallite size of 15 nm, which reveals the polycrystalline nature of these nanorods. Magnetic characterization of product was performed by EPR and VSM techniques and the results show that the CuFe2O4 nanorods are ferromagnetic. The line width of the resonance lines in FMR is about 1.8 kOe which may originate from different resonance fields of randomly distributed nanocrystals which have different orientation of magnetic easy axes.

  • 40. Altomare, Angela
    et al.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Werner, Per-Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Advances in powder pattern indexing: N-TREOR092009Inngår i: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 42, 768-775 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Powder pattern indexing can still be a challenge, despite the great recent advances in theoretical approaches, computer speed and experimental devices. More plausible unit cells, belonging to different crystal systems, are frequently found by the indexing programs, and recognition of the correct one may not be trivial. The task is, however, of extreme importance: in case of failure a lot of effort and computing time may be wasted. The classical figures of merit for estimating the unit-cell reliability {i.e.M20 [de Wolff (1968). J. Appl. Cryst.1, 108–113] and FN [Smith & Snyder (1979). J. Appl. Cryst.12, 60–65]} sometimes fail. For this reason, a new figure of merit has been introduced in N-TREOR09, the updated version of the indexing package N-TREOR [Altomare, Giacovazzo, Guagliardi, Moliterni, Rizzi & Werner (2000). J. Appl. Cryst. 33, 1180–1186], combining the information supplied by M20 with additional parameters such as the number of unindexed lines, the degree of overlap in the pattern (the so-called number of statistically independent observations), the symmetry deriving from the automatic evaluation of the extinction group, and the agreement between the calculated and observed profiles. The use of the new parameters requires a dramatic modification of the procedures used worldwide: in the approach presented here, extinction symbol and unit-cell determination are simultaneously estimated. N-TREOR09 benefits also from an improved indexing procedure in the triclinic system and has been integrated into EXPO2009, the updated version of EXPO2004 [Altomare, Caliandro, Camalli, Cuocci, Giacovazzo, Moliterni & Rizzi (2004). J. Appl. Cryst. 37, 1025–1028]. The application of the new procedure to a large set of test structures is described.

  • 41.
    Aman, Ken
    et al.
    Umeå University.
    Lindahl, Erik
    KTH, Tidigare Institutioner, Fysik.
    Edholm, Olle
    KTH, Tidigare Institutioner, Fysik.
    Håkansson, Pär
    Umeå University.
    Westlund, Per-Olof
    Umeå University.
    Structure and dynamics of interfacial water in an Lalpha phase lipid bilayer from molecular dynamics simulations.2003Inngår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 84, nr 1, 102-15 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Based on molecular dynamics simulations, an analysis of structure and dynamics is performed on interfacial water at a liquid crystalline dipalmitoylphosphatidycholine/water system. Water properties relevant for understanding NMR relaxation are emphasized. The first and second rank orientational order parameters of the water O-H bonds were calculated, where the second rank order parameter is in agreement with experimental determined quadrupolar splittings. Also, two different interfacial water regions (bound water regions) are revealed with respect to different signs of the second rank order parameter. The water reorientation correlation function reveals a mixture of fast and slow decaying parts. The fast (ps) part of the correlation function is due to local anisotropic water reorientation whereas the much slower part is due to more complicated processes including lateral diffusion along the interface and chemical exchange between free and bound water molecules. The 100-ns-long molecular dynamics simulation at constant pressure (1 atm) and at a temperature of 50 degrees C of 64 lipid molecules and 64 x 23 water molecules lack a slow water reorientation correlation component in the ns time scale. The (2)H(2)O powder spectrum of the dipalmitoylphosphatidycholine/water system is narrow and consequently, the NMR relaxation time T(2) is too short compared to experimental results.

  • 42.
    Amft, Martin
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Flerskalig materialmodellering.
    Walle, L. E.
    Ragazzon, D.
    Borg, A.
    Uvdal, P.
    Skorodumova, Natalia V.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Flerskalig materialmodellering.
    Sandell, A.
    A Molecular Mechanism for the Water-Hydroxyl Balance during Wetting of TiO22013Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, nr 33, 17078-17083 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We show that the formation of the wetting layer and the experimentally observed continuous shift of the H2O-OH balance toward molecular water at increasing coverage on a TiO2(110) surface can be rationalized on a molecular level. The mechanism is based on the initial formation of stable hydroxyl pairs, a repulsive interaction between these pairs, and an attractive interaction with respect to water molecules. The experimental data are obtained by synchrotron radiation photoelectron spectroscopy and interpreted with the aid of density functional theory calculations and Monte Carlo simulations.

  • 43.
    An, Junxue
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Biomolecular association – biolubrication perspective: Association between hyaluronan and phospholipids2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Dipalmitoylphosphatidylcholine (DPPC) vesicles were prepared by sonication and their size in sodium chloride solutions ([NaCl] = 0.116 M) containing different amount of calcium ions (0, 1, 2, 5, 10 mM) were studied by Dynamic Light Scattering (DLS). The time dependence of the particle size in various solutions was also tested. The data showed that the hydrodynamic diameter of DPPC vesicles was not affected by the Ca2+ concentration; however, the stability of DPPC vesicles was improved with the presence of Ca2+. Besides, when the temperature was above the phase transition temperature (41.5°C), the DPPC vesicles in dispersions with more than 2 mM CaCl2 remained stable for at least 2 weeks. Zeta potential of vesicles in aqueous solutions was tested by Zetasizer. The result showed that the stability of DPPC vesicles increased with increasing Ca2+ concentration with the evidence of increasing zeta potential due to the binding of Ca2+ onto vesicle bilayers. The association between zwitterionic DPPC vesicles and anionic polyelectrolyte hyaluronan (HA) was also studied by testing the hydrodynamic diameter and electrophoretic mobility change after the addition of HA. DLS results showed that the hydrodynamic diameter of DPPC vesicles increased in the presence of HA. In addition, after several days’ incubation at 55°C precipitation appeared in the DPPC-HA mixture solution. Furthermore, electrophoretic mobility of DPPC vesicles decreased after the addition of polyelectrolyte. The combined results demonstrated that the association between DPPC and HA occurred.

  • 44.
    An, Junxue
    KTH, Skolan för kemivetenskap (CHE). KTH.
    Polymers in Aqueous Lubrication2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The main objective of this thesis work was to gain understanding of the layer properties and polymer structures that were able to aid lubrication in aqueous media. To this end, three types of polyelectrolytes: a diblock copolymer, a train-of-brushes and two brush-with-anchor mucins have been utilized. Their lubrication ability in the boundary lubrication regime has been examined by Atomic Force Microscopy with colloidal probe.

    The interfacial behavior of the thermoresponsive diblock copolymer, PIPOZ60-b-PAMPTAM17,on silica was studied in the temperature interval 25-50 ˚C. The main finding is that adsorption hysteresis, due to the presence of trapped states, is important when the adsorbed layers are in contact with a dilute polymer solution. The importance of trapped states was also demonstrated in the measured friction forces, where significantly lower friction forces, at a given temperature, were encountered on cooling than on the preceding heating stage, which was attributed to increased adsorbed amount. On the heating stage the friction force decreased with increasing temperature despite the worsening of the solvent condition, and the opposite trend was observed when using pre-adsorbed layers (constant adsorbed amount) as a consequence of increased segment-segment attraction.

    The second part of the studies was devoted to the interfacial properties of mucins on PMMA. The strong affinity provided by the anchoring group of C-PSLex and C-P55 together with their more extended layer structure contribute to the superior lubrication of PMMA compared to BSM up to pressures of 8-9 MPa. This is a result of minor bridging and lateral motion of molecules along the surface during shearing. We further studied the influence of glycosylation on interfacial properties of mucin by utilizing the highly purified mucins, C-P55 and C-PSLex. Our data suggest that the longer and more branched carbohydrate side chains on C-PSLex provide lower interpenetration and better hydration lubrication at low loads compared to the shorter carbohydrate chains on C-P55. However, the longer carbohydrates appear to counteract disentanglement less efficiently, giving rise to a higher friction force at high loads.

  • 45.
    An, Junxue
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Jin, Chunsheng
    Dėdinaitė, Andra
    Holgerssond, Jan
    Karlssonb, Niclas G.
    Claesson, Per M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Influence of Glycosylation on Interfacial Properties of Recombinant Mucins: Adsorption, Surface Forces and FrictionManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Interfacial properties of two brush-with-anchor mucins, C-P55 and C-PSLex, have been investigated at the aqueous solution/poly(methylmethacrylate) (PMMA) interface. Both are recombinant mucin-type fusion proteins, produced by fusing the glycosylated mucin part of P-selectin glycoprotein ligand-1 (PSLG-1) to the Fc part of a mouse immunoglobulin in two different cells. They are mainly expressed as dimers upon production. Analysis of the O-glycans shows that the C-PSLex mucin has the longer and more branched side chains, but C-P55 has slightly higher sialic acid content. The adsorption of the mucins to PMMA surfaces was studied by quartz crystal microbalance with dissipation. The sensed mass, including the adsorbed mucin and water trapped in the layer, was found to be similar for these two mucin layers. Atomic force microscopy with colloidal probe was employed to study surface and friction forces between mucin-coated PMMA surfaces. Purely repulsive forces of steric origin were observed between mucin layers on compression, whereas a small adhesion was detected between both mucin layers on decompression. This was attributed to chain entanglement. The friction force between C-PSLex-coated PMMA is lower than that between C-P55-coated PMMA at low loads, but vice versa at high loads. We discuss our results in terms of the differences in the glycosylation composition of these two mucins.

  • 46.
    An, Junxue
    et al.
    KTH Royal Institute of Technology,Stockholm, Sweden.
    Liu, Xiaoyan
    KTH Royal Institute of Technology,Stockholm, Sweden.
    Dedinaite, Andra
    RISE - Research Institutes of Sweden, Biovetenskap och material, Kemi, material och ytor. KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science.
    Korchagina, Evgeniya
    University of Montreal, Montreal, Canada .
    Winnik, Francoise M.
    University of Montreal, Montreal, Canada ; WPI International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, Tsukuba, Ibaraki, Japan ; University of Helsinki, Helsinki, Finland.
    Claesson, Per M.
    RISE - Research Institutes of Sweden, Biovetenskap och material, Kemi, material och ytor. KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science.
    Dedinaite, Andra
    RISE - Research Institutes of Sweden, Biovetenskap och material, Kemi, material och ytor. KTH Royal Institute of Technology,Stockholm, Sweden.
    Effect of solvent quality and chain density on normal and frictional forces between electrostatically anchored thermoresponsive diblock copolymer layers2017Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 487, 88-96 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Equilibration in adsorbing polymer systems can be very slow, leading to different physical properties at a given condition depending on the pathway that was used to reach this state. Here we explore this phenomenon using a diblock copolymer consisting of a cationic anchor block and a thermoresponsive block of poly(2-isopropyl-2-oxazoline), PIPOZ. We find that at a given temperature different polymer chain densities at the silica surface are achieved depending on the previous temperature history. We explore how this affects surface and friction forces between such layers using the atomic force microscope colloidal probe technique. The surface forces are purely repulsive at temperatures <40 °C. A local force minimum at short separation develops at 40 °C and a strong attraction due to capillary condensation of a polymer-rich phase is observed close to the bulk phase separation temperature. The friction forces decrease in the cooling stage due to rehydration of the PIPOZ chain. A consequence of the adsorption hysteresis is that the friction forces measured at 25 °C are significantly lower after exposure to a temperature of 40 °C than prior to heating, which is due to higher polymer chain density on the surface after heating.

  • 47.
    Andersson, David A.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Korzhavyi, Pavel A.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Johansson, Börje
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    First-principles based calculation of binary and multicomponent phase diagrams for titanium carbonitride2008Inngår i: Calphad, ISSN 0364-5916, E-ISSN 1873-2984, Vol. 32, nr 3, 543-565 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper we have used a combined first principles and Calphad approach to calculate phase diagrams in the titanium-carbon-nitrogen system, with particular focus on the vacancy-induced ordering of the substoichiometric carbonitride phase, TiCxNy (x + y <= 1). Results from earlier Monte Carlo simulations of the low-temperature binary phase diagrams are used in order to formulate sublattice models for TiCxNy within the compound energy formalism (CEF) that are capable of describing both the low temperature ordered and the high-temperature disordered state. We parameterize these models using first-principles calculations and then we demonstrate how they can be merged with thermodynamic descriptions of the remaining Ti-C-N phases that are derived within the Calphad method by fitting model parameters to experimental data. We also discuss structural and electronic properties of the ordered end-member compounds, as well as short range order effects in the TiCxNy phase.

  • 48.
    Andersson, David A.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Korzhavyi, Pavel A.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Johansson, Börje
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Thermodynamics of structural vacancies in titanium monoxide from first principles calculations2005Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 71, nr 14, 144101- s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structure, stability and electronic properties of the low oxygen oxides of titanium, TiOx with 1/3 <= x <= 3/2, have been studied by means of accurate first-principles calculations. In both stoichiometric and nonstoichiometric TiO there are large fractions of vacant lattice sites. These so-called structural vacancies are essential for understanding the properties and phase stability of titanium oxides. Structures with an ordered arrangement of vacancies were treated with a plane wave pseudo-potential method, while calculations for structures with disordered vacancies were performed within the framework of the Korringa-Kohn-Rostoker Green's function technique. The relaxed structural parameters in general compare well with experimental data, though some discrepancies exist for stoichiometric TiO in the ideal B1 structure, i.e., without any vacancies. The equation of state as well as the elastic properties are also derived. A monoclinic, vacancy-containing, structure of stoichiometric TiO is confirmed to be stable at low temperature and pressure. Experimentally a transition from a stoichiometric cubic structure with disordered vacancies to the ideal B1 structure without any vacancies has been observed at high pressure. It is discussed how this experimental observation relates to the present theoretical results for defect-containing and defect-free TiO.

  • 49.
    Andersson, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Structure, Bonding and Chemistry of Water and Hydroxyl on Transition Metal Surfaces2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The structure, bonding and chemistry of water and hydroxyl on metal surfaces are presented. Synchrotron based x-ray photoelectron- and x-ray absorption spectroscopy along with density functional theory calculations mainly form the basis of the results. Conditions span the temperature range 35 - 520 K and pressures from ultra-high vacuum (~10 fAtm) to near ambient pressures (~1 mAtm). The results provide, e.g, new insights on the importance of hydrogen bonding for surface chemical kinetics.

    Water adsorbs intact on the Pt(111), Ru(001) and Cu(110) surfaces at low temperatures forming 2-dimensional wetting layers where bonding to the metal (M) mainly occurs via H2O-M and M-HOH bonds. Observed isotope differences in structure and kinetics for H2O and D2O adsorption on Ru(001) are due to qualitatively different surface chemistries. D2O desorbs intact but H2O dissociates in kinetic competition with desorption similar to the D2O/Cu(110) system. The intact water layers are very sensitive to x-ray and electron induced damage.

    The mixed H2O:OH phase on Ru(001) consists of stripe-like structures 4 to 6 Ru lattice parameters wide where OH decorates the edges of the stripes. On Pt(111), two different long-range ordered mixed H2O:OH structures are found to be inter-related by geometric distortions originating from the asymmetric H-bond donor-acceptor properties of OH towards H2O.

    Water adsorption on Cu(110) was studied at near ambient conditions and compared to Cu(111). Whereas Cu(111) remains clean, Cu(110) holds significant amounts of water in a mixed H2O:OH layer. The difference is explained by the differing activation barriers for water dissociation, leading to the presence of OH groups on Cu(110) which lowers the desorption kinetics of water by orders of magnitude due to the formation of strong H2O-OH bonds. By lowering the activation barrier for water dissociation on Cu(111) by pre-adsorbing atomic O, generating adsorbed OH, similar results to those on Cu(110) are obtained.

  • 50.
    Andersson, M
    et al.
    Chalmers University of Technology.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    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 phenol2002Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 106, nr 41, 10674-10679 s.Artikkel i tidsskrift (Fagfellevurdert)
    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.

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