Institutt for kjemi: Recent submissions
Now showing items 81-100 of 611
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Gruppelærerdagen – undervisningskvalitet fra første time
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-25)Ved norske universiteter er det vanlig at stipendiater eller studenter fra tidligere kull utfører en stor del av undervisningen innen realfagene. Fokus på opplæring av denne gruppen undervisere kan bidra til en positiv effekt på undervisningskvalitet og studentenes læring. Det varierer imidlertid fra institusjon til institusjon om det finnes en slik type opplæring, og omfang og kvalitet på ... -
Rhenium Biscorrole Sandwich Compounds: XAS Evidence for a New Coordination Motif
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-23)The interaction of three free-base meso-tris(p-X-phenyl)corroles H3[TpXPC] (X = H, CH3, OCH3) with Re2(CO)10 at 235 °C in the presence of K2CO3 in o-dichlorobenzene has led to putative rhenium biscorrole sandwich compounds with the formula ReH[TpXPC]2. Density functional theory calculations and Re L3-edge extended X-ray absorption fine structure measurements suggest a seven-coordinate metal center, ... -
The Perfluoro Cage Effect: A Search for Electron-Encapsulating Molecules
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-25)Quantum chemical calculations have for some time predicted that perfluorinated polyhedral organic molecules should exhibit a low-energy LUMO consisting of the overlapping inward-pointing lobes of the C−F σ* orbitals. Accordingly, these molecules should be able to encapsulate an electron within the interior of their cavities. Inspired by the recent confirmation of this prediction for perfluorocubane, ... -
Lignocellulose Conversion via Catalytic Transformations Yields Methoxyterephthalic Acid Directly from Sawdust
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-10)Poly(ethylene terephthalate) polyester represents the most common class of thermoplastic polymers widely used in the textile, bottling, and packaging industries. Terephthalic acid and ethylene glycol, both of petrochemical origin, are polymerized to yield the polyester. However, an earlier report suggests that polymerization of methoxyterephthalic acid with ethylene glycol provides a methoxy-polyester ... -
Investigation of tetrasubstituted heterocycles reveals hydantoins as a promising scaffold for development of novel antimicrobials with membranolytic properties
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-24)Mimics of antimicrobial peptides (AMPs) have been proposed as a promising class of antimicrobial agents. We report the analysis of five tetrasubstituted, cationic, amphipathic heterocycles as potential AMP mimics. The analysis showed that the heterocyclic scaffold had a strong influence on the haemolytic activity of the compounds, and the hydantoin scaffold was identified as a promising template for ... -
Contrasting the phospholipid profiles of two neoplastic cell lines reveal a high PC:PE ratio for SH-SY5Y cells relative to A431 cells
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-14)Lipids have been implicated in Parkinson's Disease (PD). We therefore studied the lipid profile of the neuroblastoma SH-SY5Y cell line, which is used extensively in PD research and compared it to that of the A431 epithelial cancer cell line. We have isolated whole cell extracts (WC) and plasma membrane (PM) fractions of both cell lines. The isolates were analyzed with 31P NMR. We observed a significant ... -
Biochemical and structural characterisation of a family GH5 cellulase from endosymbiont of shipworm P. megotara
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-04)Background Cellulases play a key role in the enzymatic conversion of plant cell-wall polysaccharides into simple and economically relevant sugars. Thus, the discovery of novel cellulases from exotic biological niches is of great interest as they may present properties that are valuable in the biorefning of lignocellulosic biomass. Results We have characterized a glycoside hydrolase 5 (GH5) domain ... -
Recolonization and recovery of an Arctic benthic community subject to mine-tailings deposits
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-22)Deposition of large volumes of mine tailings takes place in several Norwegian fjords, but the impacts on marine ecosystems have received relatively little scientific attention. At a 40 + − year old tailing deposition area for a copper mine in the Arctic fjord Repparfjorden, we investigated both short-term colonization of mine tailingscontaminated sediments through a field experiment, and the present ... -
Visible light-exposed lignin facilitates cellulose solubilization by lytic polysaccharide monooxygenases
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-24)Lytic polysaccharide monooxygenases (LPMOs) catalyze oxidative cleavage of crystalline polysaccharides such as cellulose and are crucial for the conversion of plant biomass in Nature and in industrial applications. Sunlight promotes microbial conversion of plant litter; this effect has been attributed to photochemical degradation of lignin, a major redox-active component of secondary plant cell walls ... -
Can the absolute configuration of cyclic peptides be determined with vibrational circular dichroism?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-16)Cyclic peptides show a wide range of biological activities, among others as antibacterial agents. These peptides are often large and flexible with multiple chiral centers. The determination of the stereochemistry of molecules with multiple chiral centers is a challenging and important task in drug development. Chiroptical spectroscopies such as vibrational circular dichroism (VCD) can ... -
N-Heteroaryl Carbamates from Carbon Dioxide via Chemoselective Superbase−Catalysis: Substrate Scope and Mechanistic Investigation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-16)We report a mild superbase-catalyzed and nitrogen-selective carboxylation of N-heteroaryls, with subsequent alkylation enabling the synthesis of drug-like O-alkyl carbamates in good yields (av. 86%). Our findings suggest a partial revision of the current mechanistic understanding as superbases upon mixing with indoles and azoles generally form uncharged hydrogen-bonded complexes and not ionic salts ... -
Bipartite Genomes in Enterobacterales: Independent Origins of Chromids, Elevated Openness and Donors of Horizontally Transferred Genes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-21)Multipartite bacteria have one chromosome and one or more chromid. Chromids are believed to have properties that enhance genomic flexibility, making them a favored integration site for new genes. However, the mechanism by which chromosomes and chromids jointly contribute to this flexibility is not clear. To shed light on this, we analyzed the openness of chromosomes and chromids of the two bacteria, ... -
Liposome Formulations for the Strategic Delivery of PARP1 Inhibitors: Development and Optimization
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-11)first_pagesettingsOrder Article Reprints Open AccessArticle Liposome Formulations for the Strategic Delivery of PARP1 Inhibitors: Development and Optimization by Carlota J. F. Conceição 1,2ORCID,Elin Moe 3,4,Paulo A. Ribeiro 2ORCID andMaria Raposo 2,*ORCID 1 CEFITEC, Department of Physics, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal 2 Laboratory ... -
Accurate Relativistic Real-Time Time-Dependent Density Functional Theory for Valence and Core Attosecond Transient Absorption Spectroscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-09)First principles theoretical modeling of out-of-equilibrium processes observed in attosecond pump–probe transient absorption spectroscopy (TAS) triggering pure electron dynamics remains a challenging task, especially for heavy elements and/or core excitations containing fingerprints of scalar and spin–orbit relativistic effects. To address this, we formulate a methodology for simulating TAS within ... -
Transition-Metal Isocorroles as Singlet Oxygen Sensitizers
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-04)Building on a highly efficient synthesis of pyrrole-appended isocorroles, we have worked out conditions for manganese, palladium, and platinum insertion into free-base 5/10-(2-pyrrolyl)-5,10,15-tris(4-methylphenyl)isocorrole, H<sub>2</sub>[5/10-(2-py)- TpMePiC]. Platinum insertion proved exceedingly challenging but was finally accomplished with cis-Pt(PhCN)<sub>2</sub>Cl<sub>2</sub>. All the ... -
Combination of adsorption/desorption and photocatalytic reduction processes for PFOA removal from water by using an aminated biosorbent and a UV/sulfite system
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-17)Per- and polyfluoroalkyl substances (PFAS) are stable organic chemicals, which have been used globally since the 1940s and have caused PFAS contamination around the world. This study explores perfluorooctanoic acid (PFOA) enrichment and destruction by a combined method of sorption/desorption and photocatalytic reduction. A novel biosorbent (PG-PB) was developed from raw pine bark by grafting amine ... -
Theoretical Photoelectron Spectroscopy of Low-Valent Carbon Species: A ∼6 eV Range of Ionization Potentials among Carbenes, Ylides, and Carbodiphosphoranes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-02)High-quality density functional theory calculations underscore a nearly 6 eV range for the ionization potentials (IPs) of neutral, low-valent carbon compounds, including carbenes, ylides, and zero-valent carbon compounds (carbones) such as carbodiphosphoranes (CDPs) and carbodicarbenes. Thus, adiabatic IPs as low as 5.5 ± 0.1 eV are predicted for CDPs, which are about 0.7–1.2 eV lower than those of ... -
Band structures and Z2 invariants of two-dimensional transition metal dichalcogenide monolayers from fully relativistic Dirac-Kohn-Sham theory using Gaussian-type orbitals
(Journal article; Tidsskriftartikkel, 2023-06-02)Two-dimensional (2D) materials exhibit a wide range of remarkable phenomena, many of which owe their existence to the relativistic spin-orbit coupling (SOC) effects. To understand and predict properties of materials containing heavy elements, such as the transition-metal dichalcogenides (TMDs), relativistic effects must be taken into account in first-principles calculations. We present an all-electron ... -
Goldilocks Dilemma: LPS Works Both as the Initial Target and a Barrier for the Antimicrobial Action of Cationic AMPs on E. coli
(Journal article; Tidsskriftartikkel, 2023-07-20)Antimicrobial peptides (AMPs) are generally membrane-active compounds that physically disrupt bacterial membranes. Despite extensive research, the precise mode of action of AMPs is still a topic of great debate. This work demonstrates that the initial interaction between the Gram-negative E. coli and AMPs is driven by lipopolysaccharides (LPS) that act as kinetic barriers for the binding of AMPs to ... -
Formative and Summative Automated Assessment with Multiple-Choice Question Banks
(Journal article; Tidsskriftartikkel, 2023-07-18)Digital automated assessment is a valuable and time-efficient tool for educators to provide immediate and objective feedback to learners. Automated assessment, however, puts high demands on the quality of the questions, alignment with the intended learning outcomes, and the quality of the feedback provided to the learners. We here describe the development and use of a large number (N > 180) of ...