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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

Dynamical conductivity of lithium-intercalated hexagonal boron nitride films: A memory function approach

Rukelj, Zoran

In: Physical Review B, 2020, vol. 102, no. 20, p. 205108

This work is a study of dynamical conductivity of a quasi-two-dimensional heterostructure Li(BN)8. The conducting electrons have a free-electron-like parabolic dispersion and are assumed to scatter only on acoustic phonons. The approach used to derive the generalized Drude relation with frequency and temperature dependent relaxation consists of defining the induced current density as a...

Université de Fribourg

Responsive nanofibers with embedded hierarchical lipid self-assemblies

Tien, Nguyen D. ; Maurya, Anjani K. ; Fortunato, Giuseppino ; Rottmar, Markus ; Zboray, Robert ; Erni, Rolf ; Dommann, Alex ; Rossi, René M. ; Neels, Antonia ; Sadeghpour, Amin

In: Langmuir, 2020, vol. 36, no. 40, p. 11787–11797

We introduce the design and study of a hybrid electrospun membrane with a dedicated nanoscale structural hierarchy for controlled functions in the biomedical domain. The hybrid system comprises submicrometer-sized internally self-assembled lipid nanoparticles (ISAsomes or mesosomes) embedded into the electrospun membrane with a nanofibrous polymer network. The internal structure of ISAsomes, ...

Université de Fribourg

How circular dichroism in time- and angle-resolved photoemission can be used to spectroscopically detect transient topological states in graphene

Schüler, Michael ; Giovannini, Umberto De ; Hübener, Hannes ; Rubio, Angel ; Sentef, Michael A. ; Devereaux, Thomas P. ; Werner, Philipp

In: Physical Review X, 2020, vol. 10, no. 4, p. 041013

Pumping graphene with circularly polarized light is the archetype of light-tailoring topological bands. Realizing the induced Floquet-Chern-insulator state and demonstrating clear experimental evidence for its topological nature has been a challenge, and it has become clear that scattering effects play a crucial role. We tackle this gap between theory and experiment by employing microscopic...

Université de Fribourg

Ultrafast coupled charge and spin dynamics in strongly correlated NiO

Gillmeister, Konrad ; Golež, Denis ; Chiang, Cheng-Tien ; Bittner, Nikolaj ; Pavlyukh, Yaroslav ; Berakdar, Jamal ; Werner, Philipp ; Widdra, Wolf

In: Nature Communications, 2020, vol. 11, no. 1, p. 4095

Charge excitations across an electronic band gap play an important role in opto- electronics and light harvesting. In contrast to conventional semiconductors, studies of above-band-gap photoexcitations in strongly correlated materials are still in their infancy. Here we reveal the ultrafast dynamics controlled by Hund’s physics in strongly correlated photoexcited NiO. By combining...

Université de Fribourg

Mapping the unoccupied state dispersions in ${\mathrm{Ta}}_{2}{\mathrm{NiSe}}_{5}$ with resonant inelastic x-ray scattering

Monney, Claude ; Herzog, Marc ; Pulkkinen, Aki ; Huang, Y. ; Pelliciari, Jonathan ; Olalde-Velasco, P. ; Katayama, Naoyuk ; Nohara, Minoru ; Takagi, Hide ; Schmitt, Thorsten ; Mizokawa, Takashi

In: Physical Review B, 2020, vol. 102, no. 8, p. 085148

The transition metal chalcogenide Ta2NiSe5 undergoes a second-order phase transition at Tc=328K involving a small lattice distortion. Below Tc, a band gap at the center of its Brillouin zone increases up to about 0.35 eV. In this work, we study the electronic structure of Ta2NiSe5 in its low-temperature semiconducting phase, using resonant inelastic x-ray scattering (RIXS) at the Ni L3 edge....

Université de Fribourg

A systematic review and meta-analysis on neural adaptations following blood flow restriction training: what we know and what we don’t know

Centner, Christoph ; Lauber, Benedikt

In: Frontiers in Physiology, 2020, vol. 11, p. -

Objective: To summarize the existing evidence on the long-term effects of low-load (LL) blood flow restricted (BFR) exercise on neural markers including both central and peripheral adaptations.Methods: A systematic review and meta-analysis was conducted according to the PRISMA guidelines. The literature search was performed independently by two reviewers in the following electronic databases:...

Université de Fribourg

Unconventional free charge in the correlated semimetal Nd2Ir2O7

Wang, K. ; Xu, Bing ; Rischau, C. W. ; Bachar, N. ; Michon, B. ; Teyssier, J. ; Qiu, Y. ; Ohtsuki, T. ; Cheng, Bing ; Armitage, N. P. ; Nakatsuji, S. ; van der Marel, D.

In: Nature Physics, 2020, p. -

Nd2Ir2O7 is a correlated semimetal with the pyrochlore structure, in which competing spin–orbit coupling and electron–electron interactions are believed to induce a time- reversal symmetry-broken Weyl semimetal phase characterized by pairs of topologically protected Dirac points at the Fermi energy1,2,3,4. However, the emergent properties in these materials are far from clear, and exotic...

Université de Fribourg

Assessing the impact of diagenesis on foraminiferal geochemistry from a low latitude, shallow-water drift deposit

Stainbank, Stephanie ; Spezzaferri, Silvia ; Boever, Eva De ; Bouvier, Anne-Sophie ; Chilcott, Colin ; Leau, Erica S.de ; Foubert, Anneleen ; Kunkelova, Tereza ; Pichevin, Laetitia ; Raddatz, Jacek ; Rüggeberg, Andres ; D.Wright, James ; M.Yu, Siyao ; Zhang, Manlin ; Kroon, Dick

In: Earth and Planetary Science Letters, 2020, vol. 545, p. 116390

Due to their large heat and moisture storage capabilities, the tropics are fundamental in modulating both regional and global climate. Furthermore, their thermal response during past extreme warming periods, such as super interglacials, is not fully resolved. In this regard, we present high-resolution (analytical) foraminiferal geochemical (δ18O and Mg/Ca) records for the last 1800 kyr from...

Université de Fribourg

Resonance raman optical activity shows unusual structural sensitivity for systems in resonance with multiple excited states: vitamin B12 case

Machalska, Ewa ; Zajac, Grzegorz ; Gruca, Anna ; Zobi, Fabio ; Baranska, Malgorzata ; Kaczor, Agnieszka

In: The Journal of Physical Chemistry Letters, 2020, vol. 11, no. 13, p. 5037–5043

In this work, cobalamins with different upper axial substituents and a cobalamin derivative with a ring modification were studied using chiroptical spectroscopies, in particular resonance Raman optical activity (RROA), to shed light on the influence of structural modifications on RROA spectra in these strongly chiral systems in resonance with multiple excited states at 532 nm excitation. We...