Viser treff 281-300 av 581

    • Unexpected Molecular Structure of a Putative Rhenium-Dioxo-Benzocarbaporphyrin Complex. Implications for the Highest Transition Metal Valence in a Porphyrin-Type Ligand Environment 

      Alemayehu, Abraham; Vazquez-Lima, Hugo; Teat, Simon J.; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-18)
      A combination of quantum chemical calculations and synthetic studies was used to address the possibility of very high (>6) valence states of transition metals in porphyrin‐type complexes. With corrole as a supporting ligand, DFT calculations ruled out Re(VII) and Ir(VII) dioxo complexes as stable species. Attempted rhenium insertion into benzocarbaporphyrin (BCP) ligands on the other hand led to two ...
    • Towards Rational Computational Engineering of Psychrophilic Enzymes 

      Socan, Jaka; Isaksen, Geir Villy; Brandsdal, Bjørn Olav; Åqvist, Johan Lennart Gösta (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-16)
      Cold-adapted enzymes from psychrophilic species achieve their high catalytic efficiency at low temperature by a different partitioning of the activation free energy into its enthalpic and entropic components, compared to orthologous mesophilic enzymes. Their lower activation enthalpy, partly compensated by an increased entropic penalty, has been suggested to originate from changes in flexibility of ...
    • Characterization and engineering of a DNA polymerase reveals a single amino-acid substitution in the fingers subdomain to increase strand-displacement activity of A-family prokaryotic DNA polymerases 

      Piotrowski, Yvonne; Gurung, Man Kumari; Larsen, Atle Noralf (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-09)
      <i>Background</i> - The discovery of thermostable DNA polymerases such as Taq DNA polymerase revolutionized amplification of DNA by polymerase chain reaction methods that rely on thermal cycling for strand separation. These methods are widely used in the laboratory for medical research, clinical diagnostics, criminal forensics and general molecular biology research. Today there is a growing demand ...
    • På vei mot en kollegial tilnærming til undervisning – seminarundervisning og pedagogisk opplæring av stipendiater 

      Johansen, Greta Kristine; Beerepoot, Maarten (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-19)
      Seminarundervisning har en viktig rolle i realfagsundervisning i høyere utdanning. Læringsaktivitetene i seminarene samsvarer ofte godt med eksamensformen og dermed bidrar seminarundervisning betydelig til <i>constructive alignment</i> (Biggs, 1999) i et emne. Den viktige rollen seminarundervisning har står i sterk kontrast med den begrensede eller fraværende opplæring ...
    • A thermally stable {FeNO}(8) complex: properties and biological reactivity of reduced MNO systems 

      Patra, Ashis K.; Dube, Koustubh S.; Sanders, Brian C.; Papaefthymiou, Georgia C.; Conradie, Jeanet; Ghosh, Abhik; Harrop, Todd C. (Journal article; Tidsskriftartikkel; Peer reviewed, 2012-10-06)
      Reduced nitrogen oxide ligands such as NO<sup>−</sup>/HNO or nitroxyl participate in chemistry distinct from nitric oxide (NO). Nitroxyl has been proposed to form at heme centers to generate the Enemark–Feltham designated {FeNO}<sup>8</sup> system. The synthesis of a thermally stable {FeNO}<sup>8</sup> species namely, [Co(Cp<sup>*</sup>)<sub>2</sub>][Fe(LN<sub>4</sub>)(NO)] (3), housed in a heme-like ...
    • Gold dipyrrin-bisphenolates: A combined experimental and DFT study of metal-ligand interactions 

      Thomas, Kolle E; Desbois, Nicolas; Conradie, Jeanet; Teat, Simon J.; Gros, Claude P; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-02)
      Given that noninnocent and metalloradical-type electronic structures are ubiquitous among dipyrrin-bisphenolate (DPP) complexes, we synthesized the gold(III) derivatives as potentially innocent paradigms against which the properties of other metallo-DPP derivatives can be evaluated. Electronic absorption spectra, electrochemical studies, a single-crystal X-ray structure, and DFT calculations all ...
    • The crystal structure of haemoglobin from Atlantic cod 

      Helland, Ronny; Bjørkeng, Eva katrin; Rothweiler, Ulli; Sydnes, Magne Olav; Pampanin, Daniela Maria (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-16)
      The crystal structure of haemoglobin from Atlantic cod has been solved to 2.54 A˚ resolution. The structure consists of two tetramers in the crystallographic asymmetric unit. The structure of haemoglobin obtained from one individual cod suggests polymorphism in the tetrameric assembly.
    • On derivatives of smooth functions represented in multiwavelet bases 

      Anderson, Joel; Harrison, Robert J.; Sekino, Hideo; Sundahl, Bryan; Beylkin, Gregory; Fann, George I.; Jensen, Stig Rune; Sagert, Irina (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-24)
      We construct high-order derivative operators for smooth functions represented via discontinuous multiwavelet bases. The need for such operators arises in order to avoid artifacts when computing functionals involving high-order derivatives of solutions of integral equations. Previously high-order derivatives had to be formed by repeated application of a first-derivative operator that, while uniquely ...
    • Four-component relativistic time-dependent density-functional theory using a stable noncollinear DFT ansatz applicable to both closed- and open-shell systems 

      Komorovsky, Stanislav; Cherry, Peter J.; Repisky, Michal (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-14)
      We present a formulation of relativistic linear response time-dependent density functional theory for the calculation of electronic excitation energies in the framework of the four-component Dirac-Coulomb Hamiltonian. This approach is based on the noncollinear <i>ansatz</i> originally developed by Scalmani and Frisch [J. Chem. Theory Comput. 8, 2193 (2012)] and improves upon the past treatment of ...
    • Relativistic four-component linear damped response TDDFT for electronic absorption and circular dichroism calculations 

      Konecny, Lukas; Repisky, Michal; Ruud, Kenneth; Komorovsky, Stanislav (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-21)
      We present a detailed theory, implementation, and a benchmark study of a linear damped response time-dependent density functional theory (TDDFT) based on the relativistic four-component (4c) Dirac–Kohn–Sham formalism using the restricted kinetic balance condition for the small-component basis and a noncollinear exchange–correlation kernel. The damped response equations are solved by means of a ...
    • The quantitative level of T315I mutated BCR-ABL predicts for major molecular response to second-line nilotinib or dasatinib treatment in patients with chronic myeloid leukemia 

      Lange, Thoralf; Ernst, Thomas; Gruber, Franz; Maier, Jacqueline; Cross, Michael; Müller, Martin C.; Niederwieser, Dietger; Hochhaus, Andreas; Pfirrmann, Markus (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-05)
      The BCR-ABL T315I mutation causes resistance to imatinib, nilotinib and dasatinib in chronic myeloid leukemia. Forty BCR-ABL positive patients with imatinib resistance were analyzed for T315I mutated clones after six months on nilotinib or dasatinib treatment by quantitative allele-specific ligation polymerase chain reaction with a sensitivity of 0.05%. Ligation polymerase chain reaction revealed ...
    • Engineering low-temperature expression systems for heterologous production of cold-adapted enzymes 

      Bjerga, Gro Elin Kjæreng; Lale, Rahmi; Williamson, Adele Kim (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-02-26)
      Production of psychrophilic enzymes in the commonly used mesophilic expression systems is hampered by low intrinsic stability of the recombinant enzymes at the optimal host growth temperatures. Unless strategies for low-temperature expression are advanced, research on psychrophilic enzymes may end up being biased toward those that can be stably produced in commonly used mesophilic host systems. Two ...
    • Microwave-assisted synthesis of heterocycles from aryldiazoacetates. 

      Kristoffersen, Tone (Master thesis; Mastergradsoppgave, 2017-11-15)
      A novel microwave-assisted method for generation of heterocycles have been explored. A range of 3,4 dihydroquinoxalin-2-ones have been prepared via an N-H insertion/cyclization cascade of dinucleophiles and aryldiazoacetates in moderate to good yields (12 - 80%). Reactions of aryldiazoacetates with o-phenylenediamine generated the best yields, while reactions with aliphatic and benzylic dinucleophiles ...
    • Caesium Fluoride-Mediated Hydrocarboxylation of Alkenes and Allenes: Scope and Mechanistic Insights 

      Gevorgyan, Ashot; Obst, Marc; Guttormsen, Yngve; Maseras, Feliu; Hopmann, Kathrin Helen; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-11)
      A caesium fluoride-mediated hydrocarboxylation of olefins is disclosed that does not rely on precious transition metal catalysts and ligands. The reaction occurs at atmospheric pressures of CO<sub>2</sub> in the presence of 9-BBN as a stoichiometric reductant. Stilbenes, β-substituted styrenes and allenes could be carboxylated in good yields. The developed methodology can be used for preparation of ...
    • Catalytic Intermolecular Functionalization of Benzimidazoles 

      Hansen, Jørn H; Fjellaksel, Richard (Peer reviewed; Chapter; Bokkapittel, 2019-06-25)
      This chapter describes contemporary strategies for selective catalytic intermolecular functionalization of the benzimidazole scaffold. Functionalization at nitrogen and position C-2 is well developed employing copper, palladium, rhodium, nickel, and cobalt catalysis. Direct CH activation is the predominant approach to C-2 functionalization. Nickel-based catalysts can activate C—O bonds in conjunction ...
    • Closely-related Photobacterium strains comprise the majority of bacteria in the gut of migrating Atlantic cod (Gadus morhua) 

      Le Doujet, Typhaine; De Santi, Concetta; Klemetsen, Terje; Hjerde, Erik; Willassen, Nils Peder; Haugen, Peik (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-17)
      <p><i>Background - </i>The population of Atlantic cod (<i>Gadus morhua</i>), also known as Northeast Arctic cod, migrating Atlantic cod, or simply “skrei,” lives mainly in the Barents Sea and Svalbard waters and migrates in annual cycles to the Norwegian coast in order to spawn eggs during late winter. It is the world’s largest population of Atlantic cod, and the population is distinct from the ...
    • CPPE: An Open-Source C++ and Python Library for Polarizable Embedding 

      Scheurer, Maximilian; Reinholdt, Peter; Kjellgren, Erik Rosendahl; Olsen, Jógvan Magnus Haugaard; Dreuw, Andreas; Kongsted, Jacob (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-03)
      We present a modular open-source library for polarizable embedding (PE) named CPPE. The library is implemented in C++, and it additionally provides a Python interface for rapid prototyping and experimentation in a high-level scripting language. Our library integrates seamlessly with existing quantum chemical program packages through an intuitive and minimal interface. Until now, CPPE has been ...
    • Norcorrole as a Delocalized, Antiaromatic System 

      Conradie, Jeanet; Foroutan-Nejad, Cina; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-19)
      Nickel norcorrole provides an unusual example of a molecule that is strongly antiaromatic according to the magnetic criterion, but which exhibits, according to high-quality DFT calculations, a symmetric, delocalized structure with no difference in bond length between adjacent C<sub>meso</sub>-C<sub>α</sub> bonds. A fragment molecular orbital analysis suggests that these discordant observations are ...
    • Antimicrobial activity of amphipathic α,α-disubstituted β-amino amide derivatives against ESBL–CARBA producing multi-resistant bacteria; effect of halogenation, lipophilicity and cationic character 

      Paulsen, Marianne Hagensen; Ausbacher, Dominik; Bayer, Annette; Engqvist, Magnus; Hansen, Terkel; Haug, Tor; Anderssen, Trude; Andersen, Jeanette Hammer; Sollid, Johanna U. Ericson; Strøm, Morten B. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-06)
      The rapid emergence and spread of multi-resistant bacteria have created an urgent need for new antimicrobial agents. We report here a series of amphipathic α,α-disubstituted β-amino amide derivatives with activity against 30 multi-resistant clinical isolates of Gram-positive and Gram-negative bacteria, including isolates with extended spectrum β-lactamase – carbapenemase (ESBL-CARBA) production. A ...
    • Characterization of an intertidal zone metagenome oligoribonuclease and the role of the intermolecular disulfide bond for homodimer formation and nuclease activity 

      Piotrowski, Yvonne; Berg, Kristel; Klebl, David Paul; Leiros, Ingar; Larsen, Atle Noralf (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-17)
      The gene encoding MG Orn has been identified from a metagenomic library created from the intertidal zone in Svalbard and encodes a protein of 184 amino acid residues. The <i>mg orn</i> gene has been cloned, recombinantly expressed in <i>Escherichia coli</i>, and purified to homogeneity. Biochemical characterization of the enzyme showed that it efficiently degrades short RNA oligonucleotide substrates ...