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  • 1.
    Abal, Joao P. K.
    et al.
    Univ Fed Rio Grande do Sul, Inst Fis, BR-91501970 Porto Alegre, RS, Brazil..
    Dillenburg, Rodrigo F.
    Univ Fed Rio Grande do Sul, Inst Fis, BR-91501970 Porto Alegre, RS, Brazil..
    Köhler, Mateus H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Univ Fed Santa Maria, Dept Fis, BR-97105900 Santa Maria, RS, Brazil.
    Barbosa, Marcia C.
    Univ Fed Rio Grande do Sul, Inst Fis, BR-91501970 Porto Alegre, RS, Brazil..
    Molecular Dynamics Simulations of Water Anchored in Multilayered Nanoporous MoS2 Membranes: Implications for Desalination2021In: ACS Applied Nano Materials, E-ISSN 2574-0970, Vol. 4, no 10, p. 10467-10476Article in journal (Refereed)
    Abstract [en]

    One of the most promising applications in nano-science is the design of new materials to improve water permeability and selectivity of nanoporous membranes. Understanding the molecular architecture behind these fascinating structures and how it impacts the water flow is an intricate but a necessary task. We studied here the water flux through multi-layered nanoporous molybdenum disulfide (MLNMoS2) membranes with different nanopore sizes and lengths. Molecular dynamics simulations show that the permeability does not increase with the inverse of the membrane thickness, violating the classical hydrodynamic behavior. The data also reveal that water dynamics is slower than those observed in frictionless carbon nanotubes and multilayer graphene membranes, which we explain in terms of an anchor mechanism observed in between layers. We show that the membrane permeability is critically dependent on the nanopore architecture, bringing important insights into the manufacture of new desalination membranes.

  • 2.
    Abb, Marcel J. S.
    et al.
    Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany; Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany.
    Weber, Tim
    Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany; Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany.
    Langsdorf, Daniel
    Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany; Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany.
    Koller, Volkmar
    Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany; Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany.
    Gericke, Sabrina M.
    Combustion Physics, Lund University, Box 118, S-22100 Lund, Sweden.
    Pfaff, Sebastian
    Combustion Physics, Lund University, Box 118, S-22100 Lund, Sweden.
    Busch, Michael
    Division Chemical Physics Department of Physics and Competence Centre for Catalysis, Chalmersplatsen 4, SE-41296 Göteborg, Sweden.
    Zetterberg, Johan
    Combustion Physics, Lund University, Box 118, S-22100 Lund, Sweden.
    Preobrajenski, Alexei
    MAX IV Laboratory, E120057, Fontongatan 2, 22484 Lund, Sweden.
    Grönbeck, Henrik
    Division Chemical Physics Department of Physics and Competence Centre for Catalysis, Chalmersplatsen 4, SE-41296 Göteborg, Sweden.
    Lundgren, Edvin
    Synchrotron Radiation Research, Lund University, Box 118, S-22100 Lund, Sweden.
    Over, Herbert
    Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, D-35392 Giessen, Germany; Center for Materials Research, Justus Liebig University, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany.
    Thermal Stability of Single-Crystalline IrO2(110) Layers: Spectroscopic and Adsorption Studies2020In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 124, no 28, p. 15324-15336Article in journal (Refereed)
  • 3. 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, ISSN 0009-4293, E-ISSN 2673-2424, 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.

  • 4.
    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, E-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.

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  • 5.
    Abdi, Zahra
    et al.
    Inst Adv Studies Basic Sci IASBS, Dept Chem, Zanjan 4513766731, Iran..
    Bagheri, Robabeh
    Soochow Univ, Sch Phys Sci & Technol, Coll Energy, Soochow Inst Energy & Mat Innovat, Suzhou 215006, Peoples R China.;Soochow Univ, Key Lab Adv Carbon Mat & Wearable Energy Technol, Suzhou 215006, Peoples R China..
    Reza Mohammadi, Mohammad
    Univ Sistan & Baluchestan, Dept Phys, Zahedan 9816745845, Iran..
    Song, Zhenlun
    Chinese Acad Sci, Ningbo Inst Mat Technol & Engn, Surface Dept, Surface Protect Res Grp, 519 Zhuangshi Rd, Ningbo 315201, Peoples R China..
    Görlin, Mikaela
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Dau, Holger
    Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany..
    Najafpour, Mohammad Mahdi
    Inst Adv Studies Basic Sci IASBS, Dept Chem, Zanjan 4513766731, Iran..
    In Situ Synthesis of Manganese Oxide as an Oxygen-Evolving Catalyst: A New Strategy2021In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 27, no 4, p. 1330-1336Article in journal (Refereed)
    Abstract [en]

    All studies on oxygen-evolution reaction by Mn oxides in the presence of cerium(IV) ammonium nitrate (CAN) have been so far carried out by synthesizing Mn oxides in the first step. And then, followed by the investigation of the Mn oxides in the presence of oxidants for oxygen-evolution reaction (OER). This paper presents a case study of a new and promising strategy for in situ catalyst synthesis by the adding Mn-II to either CAN or KMnO4/CAN solution, resulting in the formation of Mn-based catalysts for OER. The catalysts were characterized by scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy. Both compounds contained nano-sized particles that catalyzed OER in the presence of CAN. The turnover frequencies for both catalysts were 0.02 (mmolO2 /mol(Mn).

  • 6. Abe, Ryu
    et al.
    Bajada, Mark
    Beller, Matthias
    Bocarsly, Andrew B.
    Butt, Julea N.
    Cassiola, Flavia
    Domcke, Wolfgang
    Durrant, James R.
    Gavrielides, Stelios
    Grätzel, Michael
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hatzell, Marta C.
    König, Burkhard
    Kudo, Akihiko
    Kuehnel, Moritz F.
    Lage, Ava
    Lee, Chong-Yong
    Maneiro, Marcelino
    Minteer, Shelley D.
    Paris, Aubrey R.
    Plumeré, Nicolas
    Reek, Joost N. H.
    Reisner, Erwin
    Roy, Souvik
    Schnedermann, Christoph
    Shankar, Ravi
    Shylin, Sergii I.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Smith, Wilson A.
    Soo, Han Sen
    Wagner, Andreas
    Wielend, Dominik
    Beyond artificial photosynthesis: general discussion2019In: Faraday discussions, ISSN 1359-6640, E-ISSN 1364-5498, Vol. 215, p. 422-438Article in journal (Other (popular science, discussion, etc.))
  • 7. Abi Ghaida, Fatima
    et al.
    Brinkert, Katharina
    Chen, Ping
    DeBeer, Serena
    Hoffman, Brian M.
    Holland, Patrick L.
    Laxmi, Shoba
    MacFarlane, Doug
    Peters, Jonas C.
    Peters, John W.
    Pickett, Christopher J.
    Seefeldt, Lance C.
    Shylin, Sergii I.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Stephens, Ifan E. L.
    Vincent, Kylie A.
    Wang, Qianru
    Westhead, Olivia
    Enzymatic N2 activation: general discussion2023In: Faraday discussions, ISSN 1359-6640, E-ISSN 1364-5498, Vol. 243, p. 287-295Article in journal (Other (popular science, discussion, etc.))
  • 8.
    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.

  • 9.
    Abramavicius, V.
    et al.
    Vilnius University, Lithuania; Centre Phys Science and Technology, Lithuania.
    Pranculis, V.
    Centre Phys Science and Technology, Lithuania.
    Melianas, Armantas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    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 interfaces2016In: Scientific Reports, E-ISSN 2045-2322, Vol. 6, no 32914Article in journal (Refereed)
    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.

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  • 10.
    Abramsson, Mia L.
    et al.
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, S-17165 Stockholm, Sweden..
    Sahin, Cagla
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, S-17165 Stockholm, Sweden.;Univ Copenhagen, Linderstrom Lang Ctr Prot Sci, Dept Biol, DK-2200 Copenhagen, Denmark.;OMass Therapeut, SchrOdinger Bldg,Oxford Sci Pk, Oxford OX4 4GE, England..
    Hopper, Jonathan T. S.
    Univ Oxford, Dept Chem, Oxford OX1 3QZ, England..
    Branca, Rui M. M.
    Sci Life Lab, Dept Oncol Pathol, S-17165 Stockholm, Sweden.;Karolinska Inst, S-17165 Stockholm, Sweden..
    Danielsson, Jens
    Stockholm Univ, Dept Biochem & Biophys, S-10691 Stockholm, Sweden..
    Xu, Mingming
    Stockholm Univ, Dept Biochem & Biophys, S-10691 Stockholm, Sweden..
    Chandler, Shane A.
    Univ Oxford, Dept Chem, Oxford OX1 3QZ, England..
    Osterlund, Nicklas
    Stockholm Univ, Dept Biochem & Biophys, S-10691 Stockholm, Sweden..
    Ilag, Leopold L.
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Leppert, Axel
    Karolinska Inst, Dept Biosci & Nutr, S-14183 Huddinge, Sweden..
    Costeira-Paulo, Joana
    Uppsala Univ, Dept Chem BMC, S-75123 Uppsala, Sweden..
    Lang, Lisa
    Stockholm Univ, Dept Biochem & Biophys, S-10691 Stockholm, Sweden..
    Teilum, Kaare
    Univ Copenhagen, Linderstrom Lang Ctr Prot Sci, Dept Biol, DK-2200 Copenhagen, Denmark..
    Laganowsky, Arthur
    Texas A&M Univ, Dept Chem, College Stn, TX 77843 USA..
    Benesch, Justin L. P.
    Univ Oxford, Dept Chem, Oxford OX1 3QZ, England..
    Oliveberg, Mikael
    Stockholm Univ, Dept Biochem & Biophys, S-10691 Stockholm, Sweden..
    Robinson, Carol, V
    Univ Oxford, Dept Chem, Oxford OX1 3QZ, England..
    Marklund, Erik
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Allison, Timothy M.
    Univ Canterbury, Biomol Interact Ctr, Sch Phys & Chem Sci, Christchurch 8140, New Zealand..
    Winther, Jakob R.
    Univ Copenhagen, Linderstrom Lang Ctr Prot Sci, Dept Biol, DK-2200 Copenhagen, Denmark..
    Landreh, Michael
    Karolinska Inst, Dept Microbiol Tumor & Cell Biol, S-17165 Stockholm, Sweden..
    Charge Engineering Reveals the Roles of Ionizable Side Chains in Electrospray Ionization Mass Spectrometry2021In: JACS Au, E-ISSN 2691-3704, Vol. 1, no 12, p. 2385-2393Article in journal (Refereed)
    Abstract [en]

    In solution, the charge of a protein is intricately linked to its stability, but electrospray ionization distorts this connection, potentially limiting the ability of native mass spectrometry to inform about protein structure and dynamics. How the behavior of intact proteins in the gas phase depends on the presence and distribution of ionizable surface residues has been difficult to answer because multiple chargeable sites are present in virtually all proteins. Turning to protein engineering, we show that ionizable side chains are completely dispensable for charging under native conditions, but if present, they are preferential protonation sites. The absence of ionizable side chains results in identical charge state distributions under native-like and denaturing conditions, while coexisting conformers can be distinguished using ion mobility separation. An excess of ionizable side chains, on the other hand, effectively modulates protein ion stability. In fact, moving a single ionizable group can dramatically alter the gas-phase conformation of a protein ion. We conclude that although the sum of the charges is governed solely by Coulombic terms, their locations affect the stability of the protein in the gas phase.

  • 11.
    Abreu, Barbara
    et al.
    Univ Porto, Fac Sci, Dept Chem & Biochem, CIQUP, Rua Campo Alegre, P-4169007 Porto, Portugal..
    Rocha, Jessica
    Univ Porto, Fac Sci, Dept Chem & Biochem, CIQUP, Rua Campo Alegre, P-4169007 Porto, Portugal..
    Ferreira Fernandes, Ricardo Manuel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Regev, Oren
    Ben Gurion Univ Negev, Dept Chem Engn, IL-84105 Beer Sheva, Israel.;Ben Gurion Univ Negev, Ilse Katz Inst Nanotechnol, IL-84105 Beer Sheva, Israel..
    Furo, Istvan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Marques, Eduardo F.
    Univ Porto, Fac Sci, Dept Chem & Biochem, CIQUP, Rua Campo Alegre, P-4169007 Porto, Portugal..
    Gemini surfactants as efficient dispersants of multiwalled carbon nanotubes: Interplay of molecular parameters on nanotube dispersibility and debundling2019In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 547, p. 69-77Article in journal (Refereed)
    Abstract [en]

    Surfactants have been widely employed to debundle, disperse and stabilize carbon nanotubes in aqueous solvents. Yet, a thorough understanding of the dispersing mechanisms at molecular level is still warranted. Herein, we investigated the influence of the molecular structure of gemini surfactants on the dispersibility of multiwalled carbon nanotubes (MWNTs). We used dicationic n-s-n gemini surfactants, varying n and s, the number of alkyl tail and alkyl spacer carbons, respectively; for comparisons, single-tailed surfactant homologues were also studied. Detailed curves of dispersed MWNT concentration vs. surfactant concentration were obtained through a stringently controlled experimental procedure, allowing for molecular insight. The gemini are found to be much more efficient dispersants than their single-tailed homologues, i.e. lower surfactant concentration is needed to attain the maximum dispersed MWNT concentration. In general, the spacer length has a comparatively higher influence on the dispersing efficiency than the tail length. Further, scanning electron microscopy imaging shows a sizeable degree of MWNT debundling by the gemini surfactants in the obtained dispersions. Our observations also point to an adsorption process that does not entail the formation of micelle-like aggregates on the nanotube surface, but rather coverage by individual molecules, among which the ones that seem to be able to adapt best to the nanotube surface provide the highest efficiency. These studies are relevant for the rational design and choice of optimal dispersants for carbon nanomaterials and other similarly water-insoluble materials.

  • 12.
    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
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. 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 systems2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, p. 843-851Article in journal (Refereed)
    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.

  • 13. 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)
  • 14.
    Aderne, Rian E.
    et al.
    Pontifícia Universidade Católica do Rio de Janeiro – PUC-Rio, BRA.
    Borges, Bruno Gabriel A. L.
    Universidade Federal do Rio de Janeiro-UFRJ, BRA.
    Avila, Harold C.
    University of Atlantic, COL.
    von Kieseritzky, Fredrik
    Karolinska Institutet.
    Hellberg, Jonas
    Chemtron AB, Sweden.
    Koehler, Marlus
    Universidade Federal do Paraná-UFPR, BRA.
    Cremona, Marco
    Pontifícia Universidade Católica do Rio de Janeiro – PUC-Rio, BRA.
    Roman, Lucimara S.
    Universidade Federal do Paraná-UFPR, BRA.
    Araujo, Moyses C.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). Uppsala University.
    Rocco, Maria Luiza M.
    Universidade Federal do Rio de Janeiro-UFRJ, BRA.
    Marchiori, Cleber
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    On the energy gap determination of organic optoelectronic materials: the case of porphyrin derivatives2022In: Materials Advances, E-ISSN 2633-5409, no 3, p. 1791-1803Article in journal (Refereed)
    Abstract [en]

    The correct determination of the ionization potential (IP) and electron affinity (EA) as well as the energy gap is essential to properly characterize a series of key phenomena related to the applications of organic semiconductors. For example, energy offsets play an essential role in charge separation in organic photovoltaics. Yet there has been a lot of confusion involving the real physical meaning behind those quantities. Experimentally the energy gap can be measured by direct techniques such as UV-Vis absorption, or indirect techniques such as cyclic voltammetry (CV). Another spectroscopic method is the Reflection Electron Energy Loss Spectroscopy (REELS). Regarding data correlation, there is little consensus on how the REELS' energy gap can be interpreted in light of the energies obtained from other methodologies such as CV, UV-Vis, or photoemission. In addition, even data acquired using those traditional techniques has been misinterpreted or applied to derive conclusions beyond the limits imposed by the physics of the measurement. A similar situation also happens when different theoretical approaches are used to assess the energy gap or employed to explain outcomes from experiments. By using a set of porphyrin derivatives as model molecules, we discuss some key aspects of those important issues. The peculiar properties of these porphyrins demonstrate that even straightforward measurements or calculations performed in a group of very similar molecules need a careful interpretation of the outcomes. Differences up to 660 meV (similar to 190 meV) are found comparing REELS (electrochemical) measurements with UV-Vis energy gaps, for instance. From the theoretical point of view, a reasonable agreement with electrochemical measurements of the IP, EA, and the gap of the porphyrins is only obtained when the calculations involve the full thermodynamics of the redox processes. The purpose of this work is to shed light on the differences and similarities of those aforementioned characterization methods and provide some insight that might help one to develop a critical analysis of the different experimental and theoretical methodologies.

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  • 15.
    Adhikari, Arindam
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Pani, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Deidinaitei, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Blomberg, Eva
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Electrochemical behavior and anticorrosion properties of modified polyaniline dispersed in polyvinylacetate coating on carbon steel2008In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 53, no 12, p. 4239-4247Article in journal (Refereed)
    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.

  • 16.
    Adler, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
    Inoue, Yuuki
    Univ Tokyo, Sch Engn, Dept Mat Engn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Nilsson Ekdahl, Kristina
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology. Linnaeus Univ, Linnaeus Ctr Biomat Chem, SE-39182 Kalmar, Sweden..
    Baba, Teruhiko
    Natl Inst Adv Ind Sci & Technol, Cellular & Mol Biotechnol Res Inst CMB, AIST Tsukuba Cent 5,1-1-1 Higashi, Tsukuba, Ibaraki 3058565, Japan..
    Ishihara, Kazuhiko
    Univ Tokyo, Sch Engn, Dept Mat Engn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Nilsson, Bo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology.
    Teramura, Yuji
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology. Natl Inst Adv Ind Sci & Technol, Cellular & Mol Biotechnol Res Inst CMB, AIST Tsukuba Cent 5,1-1-1 Higashi, Tsukuba, Ibaraki 3058565, Japan..
    Effect of liposome surface modification with water-soluble phospholipid polymer chain-conjugated lipids on interaction with human plasma proteins2022In: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518, Vol. 10, no 14, p. 2512-2522Article in journal (Refereed)
    Abstract [en]

    Alternative liposome surface coatings for PEGylation to evade the immune system, particularly the complement system, have garnered significant interest. We previously reported poly(2-methacryloyloxyethyl phosphorylcholine) (MPC)-based lipids (PMPC-lipids) and investigated the surface modification of liposomes. In this study, we synthesize PMPC-lipids with polymerization degrees of 10 (MPC10-lipid), 20 (MPC20-lipid), 50 (MPC50-lipid), and 100 (MPC100-lipid), and coated liposomes with 1, 5, or 10 mol% PMPC-lipids (PMPC-liposomes). Non-modified and PEGylated liposomes are used as controls. We investigate the liposome size, surface charge, polydispersity index, and adsorption of plasma proteins to the liposomes post incubation in human plasma containing N,N,N ',N '-ethylenediamine tetraacetic acid (EDTA) or lepirudin by some methods such as sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), western blotting, and automated capillary western blot, with emphasis on the binding of complement protein C3. It is shown that the coating of liposome PMPC-lipids can suppress protein adsorption more effectively with an increase in the molecular weight and molar ratio (1-10 mol%). Apolipoprotein A-I is detected on PMPC-liposomes with a higher molecular weight and higher molar ratio of PMPC-lipids, whereas alpha(2)-macroglobulin is detected on non-modified, PEGylated, and PMPC-liposomes with a shorter polymer chain. In addition, a correlation is shown among the PMPC molecular weight, molar ratio, and C3 binding. The MPC10-lipid cannot inhibit C3 binding efficiently, whereas surface modifications with 10 mol% MPC20-lipid and 5 mol% and 10 mol% MPC50-lipid suppress both total protein and C3 binding. Hence, liposome modification with PMPC-lipids can be a possible strategy for avoiding complement activation.

  • 17.
    Adler, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
    Inoue, Yuuki
    Univ Tokyo, Sch Engn, Dept Mat Engn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Sato, Yuya
    Univ Tokyo, Sch Engn, Dept Bioengn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Ishihara, Kazuhiko
    Univ Tokyo, Sch Engn, Dept Mat Engn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan..
    Nilsson Ekdahl, Kristina
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology. Linnaeus Univ, Linnaeus Ctr Biomat Chem, SE-39182 Kalmar, Sweden..
    Nilsson, Bo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
    Teramura, Yuji
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology. Univ Tokyo, Sch Engn, Dept Bioengn, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1138656, Japan.;Natl Inst Adv Ind Sci & Technol, Cellular & Mol Biotechnol Res Inst CMB, Tsukuba Cent Fifth,1-1-1 Higashi, Tsukuba, Ibaraki 3058565, Japan..
    Synthesis of poly(2-methacryloyloxyethyl phosphorylcholine)-conjugated lipids and their characterization and surface properties of modified liposomes for protein interactions2021In: Biomaterials Science, ISSN 2047-4830, E-ISSN 2047-4849, Vol. 9, no 17, p. 5854-5867Article in journal (Refereed)
    Abstract [en]

    Poly(ethylene glycol) (PEG) is frequently used for liposomal surface modification. However, as PEGylated liposomes are cleared rapidly from circulation upon repeated injections, substitutes of PEG are being sought. We focused on a water-soluble polymer composed of 2-methacryloyloxyethyl phosphorylcholine (MPC) units, and synthesized poly(MPC) (PMPC)-conjugated lipid (PMPC-lipid) with degrees of MPC polymerization ranging from 10 to 100 (calculated molecular weight: 3 to 30 kDa). In addition, lipids with three different alkyl chains, myristoyl, palmitoyl, and stearoyl, were applied for liposomal surface coating. We studied the interactions of PMPC-lipids with plasma albumin, human complement protein C3 and fibrinogen using a quartz crystal microbalance with energy dissipation, and found that adsorption of albumin, C3 and fibrinogen could be suppressed by coating with PMPC-lipids. In particular, the effect was more pronounced for PMPC chains with higher molecular weight. We evaluated the size, polydispersity index, surface charge, and membrane fluidity of the PMPC-lipid-modified liposomes. We found that the effect of the coating on the dispersion stability was maintained over a long period (98 days). Furthermore, we also demonstrated that the anti-PEG antibody did not interact with PMPC-lipids. Thus, our findings suggest that PMPC-lipids can be used for liposomal coating.

  • 18.
    Adolfsson, Karin H.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Huang, Ping
    Department of Chemistry – Ångström Laboratory, Uppsala University, Box 523, Uppsala, 751 20, Sweden, Box 523.
    Golda-Cepa, Monika
    Faculty of Chemistry, Jagiellonian Universityul, Krakow, 30–387, Poland.
    Xu, Huan
    School of Materials Science and Physics, China University of Mining and Technology, Xuzhou, 221116, P. R. China.
    Kotarba, Andrzej
    Faculty of Chemistry, Jagiellonian Universityul, Krakow, 30–387, Poland.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Scavenging of DPPH by Persistent Free Radicals in Carbonized Particles2023In: Advanced Sustainable Systems, E-ISSN 2366-7486, Vol. 7, no 3, article id 2200425Article in journal (Refereed)
    Abstract [en]

    Persistent free radicals (PFR) in carbonized particles may play a role in degradation of environmental compounds. The influence of PFR is evaluated in various carbonized particles on their radical scavenging efficiency upon the common radical indicator 2-2-diphenyl-1-picrylhydrazyl (DPPH). Carbonized particles are derived by hydrothermal carbonization of glucose (C-W) or glucose and urea (NC-W) and ionothermal carbonization of glucose and urea ionic liquid (IL) (NC-IL). The carbonized materials contain OH/COOH, C=C, and C-O functionalities. The addition of urea introduces NH/NH2 functionalities. The content of polar surface groups is lower in IL-processed NC-IL. The scavenging ability, measured as DPPH UV–vis absorption decline, increases with concentration and time for all particles, while the efficiency changes are in the order of C-W > NC-W > NC-IL. Electron paramagnetic resonance analysis reveals similar radical concentration in all carbonized materials studied. The difference in efficiency is, thus, not directly related to the PFR concentration but rather to the type of PFR, surface functionalities and/or scavenging mechanism. According to the g-values, radicals in these particles are carbon-centered. The minor variation in g-values suggests interactions between the radicals and their environmental functional groups. This provides insights into the influence of PFR in carbonized materials on their radical scavenging efficiency.

  • 19. Adrich, P.
    et al.
    Froelich, P.
    Stockholm University, Faculty of Science, Department of Physics. Uppsala University, Sweden.
    Jonsell, Svante
    Stockholm University, Faculty of Science, Department of Physics.
    Yzombard, P.
    Production of antihydrogen atoms by 6 keV antiprotons through a positronium cloud2023In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 83, no 11, article id 1004Article in journal (Refereed)
    Abstract [en]

    We report on the first production of an antihydrogen beam by charge exchange of 6.1 keV antiprotons with a cloud of positronium in the GBAR experiment at CERN. The 100 keV antiproton beam delivered by the AD/ELENA facility was further decelerated with a pulsed drift tube. A 9 MeV electron beam from a linear accelerator produced a low energy positron beam. The positrons were accumulated in a set of two Penning-Malmberg traps. The positronium target cloud resulted from the conversion of the positrons extracted from the traps. The antiproton beam was steered onto this positronium cloud to produce the antiatoms. We observe an excess over background indicating antihydrogen production with a significance of 3-4 standard deviations.

  • 20.
    Aghbolagh, Mahdi Shahmohammadi
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Meynaq, Mohammad Yaser Khani
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Shimizu, Kenichi
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lindholm-Sethson, Britta
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Aspects on mediated glucose oxidation at a supported cubic phase2017In: Bioelectrochemistry, ISSN 1567-5394, E-ISSN 1878-562X, Vol. 118, p. 8-13Article in journal (Refereed)
    Abstract [en]

    A supported liquid crystalline cubic phase housing glucose oxidase on an electrode surface has been suggested as bio-anode in a biofuel. The purpose of this investigation is to clarify some aspect on the mediated enzymatic oxidation of glucose in such a bio-anode where the mediator ferrocene-carboxylic acid and glucose were dissolved in the solution. The enzyme glucose oxidase was housed in the water channels of the mono-olein cubic phase. The system was investigated with cyclic voltammetry at different scan rates and the temperature was varied between 15 degrees C and 30 degrees C. The diffusion coefficient of the mediator and also the film resistance was estimated showing a large decrease in the mass-transport properties as the temperature was decreased. The current from mediated oxidation of glucose at the electrode surface increased with decreasing film thickness. The transport of the mediator in the cubic phase was the rate-limiting step in the overall reaction, where the oxidation of glucose took place at the outer surface of the cubic phase.

  • 21.
    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.

  • 22.
    Agmo Hernández, Víctor
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    An overview of surface forces and the DLVO theory2023In: ChemTexts: The Textbook Journal of Chemistry, E-ISSN 2199-3793, Vol. 9, no 4, article id 10Article in journal (Refereed)
    Abstract [en]

    This lecture text focuses on surface forces and interactions in a liquid medium, with particular emphasis on the surface-surface interactions described by the DLVO theory, i.e., van der Waals attraction and electric double-layer repulsion. The text begins by describing the fundamental forces of nature, their connection to intermolecular interactions, and how the latter result in measurable forces between surfaces and macroscopical objects. A step-by-step reasoning on how DLVO forces arise is then presented, accompanied by a simplified description of the mathematical derivations of the main equations within the framework of the theory. The connection between the DLVO theory and the prediction of the stability of colloidal systems is presented. Examples on how the colloidal stability can be controlled or tuned are presented. The shortcomings of the original DLVO theory are discussed, and recent extended models dealing with these issues are briefly described. The text closes with a general overview of some of the most relevant non-DLVO interaction.

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  • 23.
    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.

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  • 24.
    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.

  • 25.
    Agosta, Lorenzo
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Atomistic simulations of structural and dynamical properties of liquids under geometric constraints2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The statistical-mechanical description of liquids represents a formidable problem in physic due to the absence of the analytical theory of the liquid state. Atomistic simulations represent a unique source of information in this respect and can be implemented in order address macroscopically measurable liquid properties, including its structure and dynamics, based on the information of the interactions between its constituent molecules. A particularly intriguing challenge is represented by the problem of studying liquids under geometric constraints like surfaces, or where the dimensionality is strongly suppressed like for liquids in 2 dimensions. Experimental measurements cannot access to these regions due to the resolution limitations. In this thesis the study of confined liquids is achieved by particle-based simulations at different level of theory. In particular 3 study cases are considered: the first is the characterization of solid-liquid interfaces. The problem of adsorbing surfaces is treated as a specific case of inorganic surfaces in contact with liquid water. TiO2, chosen as reference material, is studied in its polymorphic structures in aqueous conditions. The surface reactivity and its influence on the liquid structure is solved considering the quantum nature of the system. The mechanism of a solute adsorbing at the interface, considering the interfacial liquid properties, is also addressed. New advanced analysis tools for determining the structural and dynamical properties of water under a surface confinement and the thermodynamic associated to relative adsorption processes are developed. We are confident that this study will represent a mile stone for a systematic study of complex environments as bio-inorganic interfaces. As second case a liquid confined in a 2D surface is studied. Simple liquids having spherically symmetric interaction are very powerful in order to understand the relevant degrees of freedom that governs a certain physical process. Here we expand the definition of 2D hexatic phases to smectic systems in 3D. Finally the self-assembly of a triply periodic mesophase having a Fddd space symmetry group is fully characterized for a simple liquid. This phase can be thought as a geometrical reduction to a two-dimensional separation surface. The possibility of generating such complex network with simple particles, like in colloids, opens the frontiers for the exploration of new materials and applications.

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  • 26.
    Agosta, Lorenzo
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Thermodynamic and electronic characterization of Glycine adsorbing on TiO2 anatase (101) surface from first principles simulationsManuscript (preprint) (Other academic)
  • 27.
    Agosta, Lorenzo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Arismendi-Arrieta, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Dzugutov, Mikhail
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Origin of the Hydrophobic Behaviour of Hydrophilic CeO22023In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 62, no 35, article id e202303910Article in journal (Refereed)
    Abstract [en]

    The nature of the hydrophobicity found in rare-earth oxides is intriguing. The CeO2 (100) surface, despite its strongly hydrophilic nature, exhibits hydrophobic behaviour when immersed in water. In order to understand this puzzling and counter-intuitive effect we performed a detailed analysis of the water structure and dynamics. We report here an ab-initio molecular dynamics simulation (AIMD) study which demonstrates that the first water layer, in immediate contact with the hydroxylated CeO2 surface, is responsible for the effect behaving as a hydrophobic interface with respect to the rest of the liquid water. The hydrophobicity is manifested in several ways: a considerable diffusion enhancement of the confined liquid water as compared with bulk water at the same thermodynamic condition, a weak adhesion energy and few H-bonds above the hydrophobic water layer, which may also sustain a water droplet. These findings introduce a new concept in water/rare-earth oxide interfaces: hydrophobicity mediated by specific water patterns on a hydrophilic surface.

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  • 28.
    Agosta, Lorenzo
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Brandt, Erik G.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Lyubartsev, Alexander P.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Improved Sampling in Ab Initio-Based Free Energy Calculations of Amino Acids at Solid-Liquid Interfaces: A Tight-Binding Assessment on TiO2 Anatase (101)Manuscript (preprint) (Other academic)
    Abstract [en]

    Atomistic simulations are powerful for probing molecules at bioinorganic interfaces and excellent complements to scarcely available experimental techniques. The free energy controls the adsorption behavior of molecules on nanosurfaces, and is therefore a quantity of particular importance. Advanced sampling techniques can efficiently explore the adsorption free energy landscape, but molecular simulations with classical (Newtownian) dynamics fail to capture charge transfer and polarization at the solid-liquid interface. First principle simulations do not suffer from this limitation but come with a heavy computational load. Here, we introduce an efficient protocol to explore the free energy of adsorption in the ab initio framework. This approach accurately models the complex phenomena at bio-inorganic surfaces on the nanoscale and properly samples the relevant thermodynamic properties. We present a case study of adsorption of the Lysine and Aspartate amino acids on the anatase (101) TiO2 surface with the tight binding method. The high values of the calculated adsorption free energies highlight the importance of a proper description of the electronic state for surface binding processes.

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  • 29.
    Agosta, Lorenzo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Dzugutov, Mikhail
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Supercooled liquid-like dynamics in water near a fully hydrated titania surface: Decoupling of rotational and translational diffusion2021In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 154, no 9, article id 094708Article in journal (Refereed)
    Abstract [en]

    We report an ab initio molecular dynamics (MD) simulation investigating the effect of a fully hydrated surface of TiO2 on the water dynamics. It is found that the universal relation between the rotational and translational diffusion characteristics of bulk water is broken in the water layers near the surface with the rotational diffusion demonstrating progressive retardation relative to the translational diffusion when approaching the surface. This kind of rotation-translation decoupling has so far only been observed in the supercooled liquids approaching glass transition, and its observation in water at a normal liquid temperature is of conceptual interest. This finding is also of interest for the application-significant studies of the water interaction with fully hydrated nanoparticles. We note that this is the first observation of rotation-translation decoupling in an ab initio MD simulation of water.

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  • 30.
    Agosta, Lorenzo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Metere, Alfredo
    Lawrence Livermore Natl Lab, Phys & Life Sci Directorate, Phys Div, Livermore, CA 94550 USA.
    Oleynikov, Peter
    Shanghai Tech Univ, Sch Phys Sci & Technol, Shanghai, Peoples R China.
    Dzugutov, Mikhail
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Self-assembly of a triply periodic continuous mesophase with Fddd symmetry in simple one-component liquids2020In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 152, no 19, article id 191101Article in journal (Refereed)
    Abstract [en]

    Triply periodic continuous morphologies (networks) arising as a result of the microphase separation in block copolymer melts have so far never been observed self-assembled in systems of particles with spherically symmetric interaction. We report a molecular dynamics simulation where two simple one-component liquids form upon cooling an equilibrium network with the Fddd space group symmetry. This complexity reduction in the liquid network formation in terms of the particle geometry and the number of components evidences the generic nature of this class of phase transition, suggesting opportunities for producing these structures in a variety of new systems.

  • 31.
    Agosta, Lorenzo
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Metere, Alfredo
    Oleynikov, Peter
    Dzugutov, Mikhail
    Self-assembly of orthorhombic Fddd network in simple one-component liquidsManuscript (preprint) (Other academic)
    Abstract [en]

    Triply periodic continuous morphologies arising a result of the microphase separation in block copolymer melts have so far never been observed self-assembled in systems of particles with spherically symmetric interaction. We report a molecular dynamics simulation of two simple one-component liquids which self-assemble upon cooling into equilibrium orthorhombic continuous network morphologies with the Fddd space group symmetry reproducing the structure of those observed in block copolymers. The finding that the geometry of constituent molecules isn't relevant for the formation of triply periodic networks indicates the generic nature of this class of phase transition.

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  • 32.
    Agustin, Melissa B.
    et al.
    VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 VTT, Finland, P.O. Box 1000; Department of Food and Nutrition, Faculty of Agriculture and Forestry, University of Helsinki, P.O. Box 66, FI-00014, Helsinki, Finland, P.O. Box 66.
    Lahtinen, Maarit H.
    Department of Food and Nutrition, Faculty of Agriculture and Forestry, University of Helsinki, P.O. Box 66, FI-00014, Helsinki, Finland, P.O. Box 66.
    Kemell, Marianna
    Department of Chemistry, Faculty of Science, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland, P.O. Box 55.
    Oliaei, Erfan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Mikkonen, Kirsi S.
    Department of Food and Nutrition, Faculty of Agriculture and Forestry, University of Helsinki, P.O. Box 66, FI-00014, Helsinki, Finland, P.O. Box 66; Helsinki Institute of Sustainability Science, University of Helsinki, P.O. Box 65, FI-00014, Helsinki, Finland, P.O. Box 65.
    Grönqvist, Stina
    VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 VTT, Finland, P.O. Box 1000.
    Lehtonen, Mari
    Department of Food and Nutrition, Faculty of Agriculture and Forestry, University of Helsinki, P.O. Box 66, FI-00014, Helsinki, Finland, P.O. Box 66.
    Enzymatic crosslinking of lignin nanoparticles and nanocellulose in cryogels improves adsorption of pharmaceutical pollutants2024In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 266, article id 131168Article in journal (Refereed)
    Abstract [en]

    Pharmaceuticals, designed for treating diseases, ironically endanger humans and aquatic ecosystems as pollutants. Adsorption-based wastewater treatment could address this problem, however, creating efficient adsorbents remains a challenge. Recent efforts have shifted towards sustainable bio-based adsorbents. Here, cryogels from lignin-containing cellulose nanofibrils (LCNF) and lignin nanoparticles (LNPs) were explored as pharmaceuticals adsorbents. An enzyme-based approach using laccase was used for crosslinking instead of fossil-based chemical modification. The impact of laccase treatment on LNPs alone produced surface-crosslinked water-insoluble LNPs with preserved morphology and a hemicellulose-rich, water-soluble LNP fraction. The water-insoluble LNPs displayed a significant increase in adsorption capacity, up to 140 % and 400 % for neutral and cationic drugs, respectively. The crosslinked cryogel prepared by one-pot incubation of LNPs, LCNF and laccase showed significantly higher adsorption capacities for various pharmaceuticals in a multi-component system than pure LCNF or unmodified cryogels. The crosslinking minimized the leaching of LNPs in water, signifying enhanced binding between LNPs and LCNF. In real wastewater, the laccase-modified cryogel displayed 8–44 % removal for cationic pharmaceuticals. Overall, laccase treatment facilitated the production of bio-based adsorbents by improving the deposition of LNPs to LCNF. Finally, this work introduces a sustainable approach for engineering adsorbents, while aligning with global sustainability goals.

  • 33.
    Agustin, Melissa B.
    et al.
    Univ Helsinki, Fac Agr & Forestry, Dept Food & Nutr, POB 66, FI-00014 Helsinki, Finland..
    Lehtonen, Mari
    Univ Helsinki, Fac Agr & Forestry, Dept Food & Nutr, POB 66, FI-00014 Helsinki, Finland..
    Kemell, Marianna
    Univ Helsinki, Fac Sci, Dept Chem, POB 55, FI-00014 Helsinki, Finland..
    Lahtinen, Panu
    VTT Tech Res Ctr Finland, POB 1000, FIN-02044 Espoo, Finland..
    Oliaei, Erfan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Mikkonen, Kirsi S.
    Univ Helsinki, Fac Agr & Forestry, Dept Food & Nutr, POB 66, FI-00014 Helsinki, Finland.;Univ Helsinki, Helsinki Inst Sustainabil Sci, POB 65, FI-00014 Helsinki, Finland..
    Lignin nanoparticle-decorated nanocellulose cryogels as adsorbents for pharmaceutical pollutants2023In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 330, article id 117210Article in journal (Refereed)
    Abstract [en]

    Adsorption is a relatively simple wastewater treatment method that has the potential to mitigate the impacts of pharmaceutical pollution. This requires the development of reusable adsorbents that can simultaneously remove pharmaceuticals of varying chemical structure and properties. Here, the adsorption potential of nanostructured wood-based adsorbents towards different pharmaceuticals in a multi-component system was investigated. The adsorbents in the form of macroporous cryogels were prepared by anchoring lignin nanoparticles (LNPs) to the nanocellulose network via electrostatic attraction. The naturally anionic LNPs were anchored to cationic cellulose nanofibrils (cCNF) and the cationic LNPs (cLNPs) were combined with anionic TEMPO-oxidized CNF (TCNF), producing two sets of nanocellulose-based cryogels that also differed in their overall surface charge density. The cryogels, prepared by freeze-drying, showed layered cellulosic sheets randomly decorated with spherical lignin on the surface. They exhibited varying selectivity and efficiency in removing pharmaceuticals with differing aromaticity, polarity and ionic characters. Their adsorption potential was also affected by the type (unmodified or cationic), amount and morphology of the lignin nanomaterials, as well as the pH of the pharmaceutical solution. Overall, the findings revealed that LNPs or cLNPs can act as functionalizing and crosslinking agents to nanocellulose-based cryogels. Despite the decrease in the overall positive surface charge, the addition of LNPs to the cCNF-based cryogels showed enhanced adsorption, not only towards the anionic aromatic pharmaceutical diclofenac but also towards the aromatic cationic metoprolol (MPL) and tramadol (TRA) and neutral aromatic carbamazepine. The addition of cLNPs to TCNF-based cryogels improved the adsorption of MPL and TRA despite the decrease in the net negative surface charge. The improved adsorption was attributed to modes of removal other than electrostatic attraction, and they could be 7C-7C aromatic ring or hydrophobic interactions brought by the addition of LNPs or cLNPs. However, significant improvement was only found if the ratio of LNPs or cLNPs to nanocellulose was 0.6:1 or higher and with spherical lignin nanomaterials. As crosslinking agents, the LNPs or cLNPs affected the rheological behavior of the gels, and increased the firmness and decreased the water holding capacity of the corresponding cryogels. The resistance of the cryogels towards disintegration with exposure to water also improved with crosslinking, which eventually enabled the cryogels, especially the TCNF-based one, to be regenerated and reused for five cycles of adsorption-desorption experiment for the model pharmaceutical MPL. Thus, this study opened new opportunities to utilize LNPs in providing nanocellulose-based adsorbents with additional functional groups, which were otherwise often achieved by rigorous chemical modifications, at the same time, crosslinking the nanocellulose network.

  • 34.
    Agustin, Melissa B.
    et al.
    Department of Food and Nutrition, Faculty of Agriculture and Forestry, University of Helsinki, P.O. Box 66, FI-00014, Helsinki, Finland; VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044, Espoo, Finland.
    Nematollahi, Neda
    Department of Food and Nutrition, Faculty of Agriculture and Forestry, University of Helsinki, P.O. Box 66, FI-00014, Helsinki, Finland.
    Bhattarai, Mamata
    Department of Food and Nutrition, Faculty of Agriculture and Forestry, University of Helsinki, P.O. Box 66, FI-00014, Helsinki, Finland; Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16300, 00076, Aalto, Finland.
    Oliaei, Erfan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites.
    Lehtonen, Mari
    Department of Food and Nutrition, Faculty of Agriculture and Forestry, University of Helsinki, P.O. Box 66, FI-00014, Helsinki, Finland.
    Rojas, Orlando J.
    Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16300, 00076, Aalto, Finland; Bioproducts Institute, Department of Chemical and Biological Engineering, Department of Chemistry and Department of Wood Science, University of British Columbia, 2360, East Mall, Vancouver, BC, V6T 1Z3, Canada.
    Mikkonen, Kirsi S.
    Department of Food and Nutrition, Faculty of Agriculture and Forestry, University of Helsinki, P.O. Box 66, FI-00014, Helsinki, Finland; Helsinki Institute of Sustainability Science, University of Helsinki, P.O. Box 65, FI-00014, Helsinki, Finland.
    Lignin nanoparticles as co-stabilizers and modifiers of nanocellulose-based Pickering emulsions and foams2023In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 30, no 14, p. 8955-8971Article in journal (Refereed)
    Abstract [en]

    Nanocellulose is very hydrophilic, preventing interactions with the oil phase in Pickering emulsions. This limitation is herein addressed by incorporating lignin nanoparticles (LNPs) as co-stabilizers of nanocellulose-based Pickering emulsions. LNP addition decreases the oil droplet size and slows creaming at pH 5 and 8 and with increasing LNP content. Emulsification at pH 3 and LNP cationization lead to droplet flocculation and rapid creaming. LNP application for emulsification, prior or simultaneously with nanocellulose, favors stability given the improved interactions with the oil phase. The Pickering emulsions can be freeze–dried, enabling the recovery of a solid macroporous foam that can act as adsorbent for pharmaceutical pollutants. Overall, the properties of nanocellulose-based Pickering emulsions and foams can be tailored by LNP addition. This strategy offers a unique, green approach to stabilize biphasic systems using bio-based nanomaterials without tedious and costly modification procedures.

  • 35.
    Ahlawat, Paramvir
    et al.
    Ecole Polytech Fed Lausanne EPFL, Lab Computat Chem & Biochem, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland..
    Hinderhofer, Alexander
    Univ Tubingen, Inst Angew Phys, D-72076 Tubingen, Germany..
    Alharbi, Essa A.
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland..
    Lu, Haizhou
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland.;Ecole Polytech Fed Lausanne, Lab Photomol Sci, Inst Chem Sci Engn, CH-1015 Lausanne, Switzerland..
    Ummadisingu, Amita
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland..
    Niu, Haiyang
    Swiss Fed Inst Technol, Dept Chem & Appl Biosci, CH-8092 Zurich, Switzerland.;Univ Svizzera Italiana, Fac Informat, Ist Sci Computaz, Via G Buffi 13, CH-6900 Lugano, Switzerland..
    Invernizzi, Michele
    Swiss Fed Inst Technol, Dept Chem & Appl Biosci, CH-8092 Zurich, Switzerland.;Univ Svizzera Italiana, Fac Informat, Ist Sci Computaz, Via G Buffi 13, CH-6900 Lugano, Switzerland.;Italian Inst Technol, Via Morego 30, I-16163 Genoa, Italy..
    Zakeeruddin, Shaik Mohammed
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland..
    Dar, M. Ibrahim
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland.;Univ Cambridge, Dept Phys, Cavendish Lab, Cambridge CB3 0HE, England..
    Schreiber, Frank
    Univ Tubingen, Inst Angew Phys, D-72076 Tubingen, Germany..
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Ecole Polytech Fed Lausanne, Lab Photomol Sci, Inst Chem Sci Engn, CH-1015 Lausanne, Switzerland..
    Graetzel, Michael
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland..
    Rothlisberger, Ursula
    Ecole Polytech Fed Lausanne EPFL, Lab Computat Chem & Biochem, Inst Chem Sci & Engn, CH-1015 Lausanne, Switzerland..
    Parrinello, Michele
    Swiss Fed Inst Technol, Dept Chem & Appl Biosci, CH-8092 Zurich, Switzerland.;Univ Svizzera Italiana, Fac Informat, Ist Sci Computaz, Via G Buffi 13, CH-6900 Lugano, Switzerland.;Italian Inst Technol, Via Morego 30, I-16163 Genoa, Italy..
    A combined molecular dynamics and experimental study of two-step process enabling low-temperature formation of phase-pure alpha-FAPbI32021In: Science Advances, E-ISSN 2375-2548, Vol. 7, no 17, article id eabe3326Article in journal (Refereed)
    Abstract [en]

    It is well established that the lack of understanding the crystallization process in a two-step sequential deposition has a direct impact on efficiency, stability, and reproducibility of perovskite solar cells. Here, we try to understand the solid-solid phase transition occurring during the two-step sequential deposition of methylammonium lead iodide and formamidinium lead iodide. Using metadynamics, x-ray diffraction, and Raman spectroscopy, we reveal the microscopic details of this process. We find that the formation of perovskite proceeds through intermediate structures and report polymorphs found for methylammonium lead iodide and formamidinium lead iodide. From simulations, we discover a possible crystallization pathway for the highly efficient metastable alpha phase of formamidinium lead iodide. Guided by these simulations, we perform experiments that result in the low-temperature crystallization of phase-pure alpha-formamidinium lead iodide.

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  • 36. 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)
  • 37.
    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.

  • 38.
    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.

  • 39.
    Ahlstrand, Emma
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Hermansson, Kersti
    Uppsala University.
    Friedman, Ran
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    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.

  • 40.
    Ahlstrand, Emma
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Zukerman Schpector, Julio
    Universidade Federal de São Carlos, Brazil.
    Friedman, Ran
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Computer simulations of alkali-acetate solutions: Accuracy of the forcefields in difference concentrations2017In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 147, p. 1-10, article id 194102Article in journal (Refereed)
    Abstract [en]

    When proteins are solvated in electrolyte solutions that contain alkali ions, the ions interact mostlywith carboxylates on the protein surface. Correctly accounting for alkali-carboxylate interactionsis thus important for realistic simulations of proteins. Acetates are the simplest carboxylates thatare amphipathic, and experimental data for alkali acetate solutions are available and can be comparedwith observables obtained from simulations. We carried out molecular dynamics simulations of alkali acetate solutions using polarizable and non-polarizable forcefields and examined the ionacetateinteractions. In particular, activity coefficients and association constants were studied in a range of concentrations (0.03, 0.1, and 1M). In addition, quantum-mechanics (QM) based energy decomposition analysis was performed in order to estimate the contribution of polarization, electrostatics, dispersion, and QM (non-classical) effects on the cation-acetate and cation-water interactions. Simulations of Li-acetate solutions in general overestimated the binding of Li+ and acetates. In lower concentrations, the activity coefficients of alkali-acetate solutions were too high, which is suggested to be due to the simulation protocol and not the forcefields. Energy decomposition analysis suggested that improvement of the forcefield parameters to enable accurate simulations of Li-acetate solution scan be achieved but may require the use of a polarizable forcefield. Importantly, simulations with some ion parameters could not reproduce the correct ion-oxygen distances, which calls for caution in thechoice of ion parameters when protein simulations are performed in electrolyte solutions.

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  • 41.
    Ahlström, Peter
    et al.
    University of Borås, School of Engineering.
    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 USA2008In: Proceedings of the 100th Annual Meeting of the American Institute for Chemical Engineering, 2008Conference paper (Refereed)
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  • 42.
    Ahlström, Peter
    et al.
    University of Borås, School of Engineering.
    Moodley, Suren
    University of Borås, School of Engineering.
    Bolton, Kim
    University of Borås, School of Engineering.
    Ramjugernath, D.
    University of Borås, School of Engineering.
    Computer Simulations of Vapor-Liquid-Liquid Equilibria Involving Hydrocarbons and Water2008In: 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, 2008Conference paper (Other academic)
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  • 43.
    Ahmad, Shargeel
    et al.
    Dalian Univ Technol, Inst Artificial Photosynth, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Liu, Jinxuan
    Dalian Univ Technol, Inst Artificial Photosynth, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Gong, Chenghuan
    Dalian Univ Technol, Inst Artificial Photosynth, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Zhao, Jianzhang
    Dalian Univ Technol, Inst Artificial Photosynth, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. Dalian Univ Technol, Inst Artificial Photosynth, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Photon Up-Conversion via Epitaxial Surface-Supported Metal-Organic Framework Thin Films with Enhanced Photocurrent2018In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 1, no 2, p. 249-253Article in journal (Refereed)
    Abstract [en]

    We report a new triplet-triplet annihilation photon up-conversion (TTA-UC) system using an epitaxial Zn-perylene surface-supported metal-organic framework (SURMOF) grown on metal oxide surface as "emitter", and a platinum octaethylporphyrin (PtOEP) as "sensitizer" in [Co(bpy)(3)](2+/3+) acetonitrile solution. It has been demonstrated that the photocurrent can be significantly enhanced relative to epitaxial Zn-perylene SURMOF due to the TTA-UC mechanism. This initial result holds promising applications toward SURMOF-based solar energy conversion devices.

  • 44.
    Ahmed, Hamzah
    et al.
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Shimpi, Manishkumar R.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Velaga, Sitaram P.
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Relationship between mechanical properties and crystal structure in cocrystals and salt of paracetamol2017In: Drug Development and Industrial Pharmacy, ISSN 0363-9045, E-ISSN 1520-5762, Vol. 43, no 1, p. 89-97Article in journal (Refereed)
    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.

  • 45.
    Ahmed, Mukhtiar
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Bhowmick, Sourav
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Filippov, Andrei
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Johansson, Patrik
    Materials Physics, Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Ionic Liquids and Electrolytes with Flexible Aromatic Anions2023In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 29, no 41, article id e202301000Article in journal (Refereed)
    Abstract [en]

    Five new n-tetrabutylphosphonium (P4444)+ cation based ionic liquids (ILs) with oligoether substituted aromatic carboxylate anions have been synthesized. The nature and position of the oligoether chain affect thermal stability (up to 330 ºC), phase behaviour (Tg < -55 ºC) and ion transport. Furthermore, with the aim of application in lithium batteries, electrolytes were created for two of the ILs by 10 mol% doping using the corresponding Li-salts. This affects the ion diffusion negatively, from being higher and equal for cations and anions to lower for all ions and unequal. This is due to the stronger ionic interactions and formation of aggregates, primarily between the Li+ ions and the carboxylate group of the anions. Electrochemically, the electrolytes have electrochemical stability windows up to 3.5 V, giving some promise for battery application.

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  • 46.
    Ahmed, Mukhtiar
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Rao, Soniya S.
    Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Filippov, Andrei
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Johansson, Patrik
    Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Aromatic Heterocyclic Anion Based Ionic Liquids and Electrolytes2023In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 25, no 4, p. 3502-3512Article in journal (Refereed)
    Abstract [en]

    Five new ionic materials comprising fluorine-free aromatic heterocyclic anions based on pyridine and pyrazine combined with a common n-tetrabutylphosphonium cation, (P4444)+, result in two room temperature ionic liquids (RTILs), one semi-solid, and two organic ionic plastic crystals (OIPCs) with melting points >20 °C. The OIPCs showed a plastic crystalline phase, multiple solid–solid transitions, and plastic crystalline and melt phases. For both the neat RTILs and the Li+ conducting electrolytes, the nature and strength of the ion–ion interactions mainly depend on the position of the nitrogen atom with respect to the carboxylate group in the anions. Furthermore, for the RTILs the ionic conductivity is effected by the electronic structure and flexibility of the ions and the anions diffuse faster than the (P4444)+ cation, but are slowed down in the electrolytes due to the strong electrostatic interactions between the carboxylate group of the anions and the Li+, as shown both experimentally and computationally. Overall, this study describes the effect of structural tuning of aromatic anions on the ion–ion interactions and introduces new ionic materials with promising properties to be used as solid and liquid electrolytes in energy storage devices.

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  • 47.
    Ahmed, Safya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Encapsulation of a biologic for pulmonary delivery via inhalation2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In recent years biologics have gained a lot of interest in the pharmaceutical industry due to their appealing features. However, the concern with these types of drugs is in regard to the chosen delivery route, which is limited to parenteral injections today. Pulmonary delivery is another alternative route that can be used to deliver the biologic, which is a route that is less invasive than the parenteral routes. Additionally, it bypasses the gastrointestinal system which reduces the risk of degrading the biologic. When delivering the drugs it can be advantageous to use drug carriers which will enable the drug to be delivered at high concentrations to its target. 

    In this thesis, mesoporous silica particles were used as excipients to deliver a biologic via inhalation for pulmonary delivery. The particles being used have been specially designed by the life science company, Nanologica AB (publ), to be used in dry powder inhaler formulations. Lipase originating from mucor miehei was loaded into the NLAB SPIRO® particles using two different methods: incipient wetness and adsorption. Loading with the adsorption method showed to be non-efficient and non-linear  with the change in pH. A more efficient loading was, however, obtained with the incipient wetness method, where the 2.5 wt% and 5 wt% loaded particles were the most homogenous. Aerosolization studies of these two loaded particles were performed in a reduced Next generation impactor (rNGI) and the fine particle fraction (FPF) was similar to that of the unloaded particles, indicating that the loading of the biologic did not affect their ability to be aerosolized and deposited in the lungs. Release studies of the encapsulated lipase in simulated lung conditions showed that more than 90% of the lipase is released within 2 hours. Initial results from an activity assay indicated that the released lipase was in active form, however further work to quantify the activity is required.

  • 48.
    Ahmed, Taha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nanostructured ZnO and metal chalcogenide films for solar photocatalysis2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The increasing demand for clean energy and safe water resources has driven the development of efficient and sustainable technologies. Among these technologies, photocatalysis using semiconducting materials has emerged as a promising solution for both solar hydrogen generation and water purification. Low-dimensional ZnO, including nanorods, nanoparticles, and quantum confined particles (so called quantum dots), has demonstrated excellent photocatalytic properties due to their large surface area, high electron mobility, and tunable band gap.

    The work in this thesis aims to investigate the potential of low-dimensional ZnO alone and in combination with CdS and Fe2O3 for solar hydrogen generation and photocatalytic water purification. The thesis includes a comprehensive analysis of the synthesis, characterization, and optimization of low-dimensional ZnO-based photocatalyst systems for solar hydrogen generation and photocatalytic water purification. Additionally, the thesis will evaluate the performance of the ZnO-based photocatalysts under different experimental conditions, either as photoelectrodes or as distributed particle systems for water purification. The work includes detailed size control of ZnO by itself in dimensions below 10 nm using a hydrothermal method, to provide an increased total surface area and introduce quantum confinement effects that increase the band gap to enable degradation of chemical bonds in a model pollutant in a distributed system for water purification. The work also includes a relatively detailed study of the phonon–phonon and electron–phonon coupling as a function of dimension from 10 nm to 150 nm for ZnO using non-resonant and resonant Raman spectroscopy. Ultimately, the thesis aims to provide insight into the potential of low-dimensional ZnO alone and in combination with other inorganic materials for solar hydrogen generation and photocatalytic water purification and pave the way for the development of efficient and sustainable technologies for clean energy and safe water resources.

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  • 49.
    Ahmed, Taha
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Optical Quantum Confinement in Ultrasmall ZnO and the Effect of Size on Their Photocatalytic Activity2020In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 124, no 11, p. 6395-6404Article in journal (Refereed)
    Abstract [en]

    Zinc oxide is a well-known metal oxide semiconductor with a wide direct band gap that offers a promising alternative to titanium oxide in photocatalytic applications. ZnO is studied here as quantum dots (QDs) in colloidal suspensions, where ultrasmall nanoparticles of ZnO show optical quantum confinement with a band gap opening for particles below 9 nm in diameter from the shift of the band edge energies. The optical properties of growing ZnO QDs are determined with Tauc analysis, and a system of QDs for the treatment and degradation of distributed threats is analyzed using an organic probe molecule, methylene blue, whose UV/vis spectrum is analyzed in some detail. The effect of optical properties of the QDs and the kinetics of dye degradation are quantified for low-dimensional ZnO materials in the range of 3-8 nm and show a substantial increase in photocatalytic activity compared to larger ZnO particles. This is attributed to a combined effect from the increased surface area as well as a quantum confinement effect that goes beyond the increased surface area. The results show a significantly higher photocatalytic activity for the QDs between 3 and 6 nm with a complete decolorization of the organic probe molecule, while QDs from 6 nm and upward in diameter show signs of competing reduction reactions. Our study shows that ultrasmall ZnO particles have a reactivity beyond that which is expected because of their increased surface area and also demonstrates size-dependent reaction pathways, which introduces the possibility for size-selective catalysis.

  • 50.
    Ahmed, Taha
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Thyr, Jakob
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Naim Katea, Sarmad
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Westin, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Phonon–phonon and electron–phonon coupling in nano-dimensional ZnOManuscript (preprint) (Other academic)
    Abstract [en]

    Thermal losses through vibrational coupling are critical bottlenecks limiting several materials classes from reaching their full potential. Altering the phonon–phonon and electron–phonon coupling by controlled suppression of vibrational degrees of freedom through low-dimensionality are promising but still largely unexplored approaches. Here we report a detailed study of the first- and second-order Raman processes as a function of size for low-dimensional ZnO. Wurtzite ZnO nanoparticles were synthesised into 3D frameworks of ZnO crystallites, with tailored crystallite diameters from 10 nm to 150 nm and characterised by electron microscopy, X-ray diffraction and non-resonant and resonant Raman spectroscopy.

    We present a short derivation of how resonance Raman and the relation between the longitudinal optical (LO) phonons can be utilised to quantify the electron–phonon coupling, its merits, and limitations. Theoretical Raman response using density functional theory is corroborating the experimental data in assigning first- and second-order Raman modes. The Lyddane-Sachs-Teller equation was applied to the measured LO–TO split and revealed no change in the ratio between the static and high-frequency dielectric constant with changing ZnO dimension from 10 nm to 150 nm. The second-order Raman revealed a phonon–phonon coupling that generally increased with particle size and markedly so for differential modes. Resonance Raman showed the fundamental LO mode and the 2nd, 3rd, and 4th overtones. The intensity relation between the fundamental LO mode and its overtones enabled the extraction of the change in electron–phonon coupling via the Huang-Rhys parameter as a function of particle size, which showed an increase with particle size.

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