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Université de Fribourg

Bacterial oxidases of the cytochrome bd family: redox enzymes of unique structure, function, and utility as drug targets

Borisov, Vitaliy B. ; Siletsky, Sergey A. ; Paiardini, Alessandro ; Hoogewijs, David ; Forte, Elena ; Giuffrè, Alessandro ; Poole, Robert K.

In: Antioxidants & Redox Signaling, 2020, p. ars.2020.8039

Significance: Cytochrome bd is a ubiquinol:oxygen oxidoreductase of many prokaryotic respiratory chains with a unique structure and functional characteristics. Its primary role is to couple the reduction of molecular oxygen, even at submicromolar concentrations, to water with the generation of a proton motive force used for adenosine triphosphate production. Cytochrome bd is found in many...

Université de Fribourg

Shear stress-responsive polymersome nanoreactors inspired by the marine bioluminescence of dinoflagellates

Rifaie‐Graham, Omar ; Galensowske, Nikolas F. B. ; Dean, Charlie ; Pollard, Jonas ; Balog, Sandor ; Gouveia, Micael G. ; Chami, Mohamed ; Vian, Antoine ; Amstad, Esther ; Lattuada, Marco ; Bruns, Nico

In: Angewandte Chemie International Edition, 2020, p. -

Some marine plankton called dinoflagellates emit light in response to the movement of surrounding water, resulting in a phenomenon called milky seas or sea sparkle. The underlying concept, a shear-stress induced permeabilisation of biocatalytic reaction compartments, is transferred to polymer-based nanoreactors. Amphiphilic block copolymers that carry nucleobases in their hydrophobic block...

Université de Fribourg

Multicellular human alveolar model composed of epithelial cells and primary immune cells for hazard assessment

Barosova, Hana ; Drasler, Barbara ; Petri-Fink, Alke ; Rothen-Rutishauser, Barbara

In: JoVE (Journal of Visualized Experiments), 2020, no. 159, p. e61090

A human alveolar cell coculture model is described here for simulation of the alveolar epithelial tissue barrier composed of alveolar epithelial type II cells and two types of immune cells (i.e., human monocyte-derived macrophages [MDMs] and dendritic cells [MDDCs]). A protocol for assembling the multicellular model is provided. Alveolar epithelial cells (A549 cell line) are grown and...

Université de Fribourg

Indirect solvent assisted tautomerism in 4-substituted phthalimide 2-hydroxy-Schiff bases

Yordanov, Dancho ; Deneva, Vera ; Georgiev, Anton ; Crochet, Aurelien ; Fromm, Katharina M. ; Antonova, Liudmil

In: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2020, vol. 237, p. 118416

The paper presents the synthesis and characterization of two 4-substituted phthalimide 2-hydroxy-Schiff bases containing salicylic (4) and 2-hydroxy-1-naphthyl (5) moieties. The structural differences of 2-hydroxyaryl substituents, resulting in different enol/keto tautomeric behaviour, depending on the solvent environment were studied by absorption UV–Vis spectroscopy. Compound 5 is...

Université de Fribourg

Classification and characterization of nonequilibrium Higgs modes in unconventional superconductors

Schwarz, L. ; Fauseweh, B. ; Tsuji, N. ; Cheng, N. ; Bittner, Nikolaj ; Krull, H. ; Berciu, M. ; Uhrig, G.S. ; Schnyder, A.P. ; Kaiser, S. ; Manske, D.

In: Nature Communications, 2020, vol. 11, no. 1, p. 1–9

Recent findings of new Higgs modes in unconventional superconductors require a classification and characterization of the modes allowed by nontrivial gap symmetry. Here we develop a theory for a tailored nonequilibrium quantum quench to excite all possible oscillation symmetries of a superconducting condensate. We show that both a finite momentum transfer and quench symmetry allow for an...

Université de Neuchâtel

Towards compact ultralow phase noise lasers and microwave signals based on new approaches

Brochard, Pierre ; Südmeyer, Thomas (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2019.

Today, the lowest phase noise microwave signals are generated optically by frequency division of an ultra-stable optical reference using a femtosecond frequency comb. In the commonly used approach, the ultra-stable optical reference is obtained by frequency-stabilizing a laser to a high-finesse ultra-low expansion optical cavity, and the frequency division is performed by optically locking a...

Université de Fribourg

Multiband nonequilibrium G W + EDMFT formalism for correlated insulators

Golež, Denis ; Eckstein, Martin ; Werner, Philipp

In: Physical Review B, 2019, vol. 100, no. 23, p. 235117

We study the dynamics of charge-transfer insulators after a photoexcitation using the three-band Emery model which is relevant for the description of cuprate superconductors. We provide a detailed derivation of the nonequilibrium extension of the multiband GW + EDMFT formalism and the corresponding downfolding procedure. The Peierls construction of the electron-light coupling is generalized...

Université de Fribourg

Light-induced evaporative cooling of holes in the Hubbard model

Werner, Philipp ; Eckstein, Martin ; Müller, Markus ; Refael, Gil

In: Nature Communications, 2019, vol. 10, no. 1, p. 5556

An elusive goal in the field of driven quantum matter is the induction of long-range order. Here, we propose a mechanism based on light-induced evaporative cooling of holes in a correlated fermionic system. Since the entropy of a filled narrow band grows rapidly with hole doping, the isentropic transfer of holes from a doped Mott insulator to such a band results in a drop of temperature....

Université de Fribourg

Catalytic living ring opening metathesis polymerisation: the importance of ring strain in chain transfer agents

Liu, Peng ; Yasir, Mohammad ; Kilbinger, Andreas F. M.

In: Angewandte Chemie International Edition, 2019, vol. 58, no. 43, p. 15278–15282

A recently developed catalytic living ring opening metathesis polymerisation (ROMP) was investigated using a series of reversible chain transfer agents (CTA) carrying either cyclopentene or cyclohexene rings, differing only in ring strain. All cyclopentene derivatives examined showed significantly faster reaction rates than the corresponding cyclohexene derivatives. This resulted in lower...

Université de Fribourg

Tautomerism as primary signaling mechanism in metal sensing: the case of amide group

Deneva, Vera ; Dobrikov, Georgi ; Crochet, Aurelien ; Nedeltcheva, Daniela ; Fromm, Katharina M. ; Antonov, Liudmil

In: Beilstein Journal of Organic Chemistry, 2019, vol. 15, no. 1, p. 1898–1906

The concept for sensing systems using the tautomerism as elementary signaling process has been further developed by synthesizing a ligand containing 4- (phenyldiazenyl)naphthalene-1-ol as a tautomeric block and an amide group as metal capturing antenna. Although it has been expected that the intramolecular hydrogen bonding (between the tautomeric hydroxy group and the nitrogen atom from the...