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Université de Fribourg

Insights into the mechanism of photosynthetic H 2 evolution catalyzed by a heptacoordinate cobalt complex

Lucarini, Fiorella ; Fize, Jennifer ; Morozan, Adina ; Marazzi, Marco ; Natali, Mirco ; Pastore, Mariachiara ; Artero, Vincent ; Ruggi, Albert

In: Sustainable Energy & Fuels, 2020, vol. 4, no. 2, p. 589–599

H2 evolution catalyzed by a heptacoordinate complex under both electro- (1) and photo-chemical (2) conditions is analyzed in detail in order to gain insights into the mechanism of the processes. The complex shows high catalytic activity for hydrogen production in acetonitrile, in the presence of trifluoroacetic acid and triethylammonium tetrafluoroborate as proton sources. Foot-of-the-wave...

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

Holistic view on cell survival and dna damage: how model-based data analysis supports exploration of dynamics in biological systems

Weyland, Mathias S. ; Thumser-Henner, Pauline ; Nytko, Katarzyna J. ; Rohrer Bley, Carla ; Ulzega, Simone ; Petri-Fink, Alke ; Lattuada, Marco ; Füchslin, Rudolf M. ; Scheidegger, Stephan

In: Computational and Mathematical Methods in Medicine, 2020, vol. 2020, p. 1–11

In this work, a method is established to calibrate a model that describes the basic dynamics of DNA damage and repair. The model can be used to extend planning for radiotherapy and hyperthermia in order to include the biological effects. In contrast to “syntactic” models (e.g., describing molecular kinetics), the model used here describes radiobiological semantics, resulting in a more...

Université de Fribourg

Bimetallic salen-based compounds and their potential applications

Finelli, Alba ; Abram, Sarah-Luise ; Hérault, Nelly ; Crochet, Aurélien ; Fromm, Katharina M.

In: Crystal Growth & Design, 2020, vol. 20, no. 8, p. 4945–4958

The new bimetallic coordination compounds [LNiAg(NO3)], [LCuMn(NO3)2], [LCuCu(NO3)2], [LCuZn(NO3)2], and [{LCuBi(NO3)3}(ACN)] have been synthesized from a salen-type ligand L containing two distinct coordination sites to accommodate (different) metal ions M1 and M2. In the solid state, the formation of 1:1 compounds (LCu:M2) is always observed, but interactions between the compounds lead to ...

Université de Fribourg

Knowledge of results during vertical jump testing: an effective method to increase the performance but not the consistency of vertical jumps

García-Ramos, Amador ; Janicijevic, Danica ; Cobo-Font, Juande ; Marcos-Frutos, Daniel ; Fernandes, John F. T. ; Taube, Wolfgang ; Pérez-Castilla, Alejandro

In: Sports Biomechanics, 2020, vol. 0, no. 0, p. 1–13

This study aimed to determine whether the provision of jump height feedback (knowledge of result; KR) can increase the performance and the consistency of output variables. In a randomised order, sixteen participants performed six squat or countermovement jumps (three from a 90º knee angle and three from a self-preferred knee angle) with or without KR over four sessions. The provision of KR...

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

Isolation of cellulose nanofibers from Oryza sativa residues via tempo mediated oxidation

Madivoli, Edwin S. ; Kareru, Patrick G. ; Gachanja, Anthony N. ; Mugo, Samuel M. ; Sujee, David M. ; Fromm, Katharina M.

In: Journal of Natural Fibers, 2020, p. 1–13

Cellulose nanocrystals (CNCs) or cellulose nanofibers (CNFs) with different morphologies, chemical, mechanical and physical properties can be obtained when microcrystalline cellulose is subjected to enzymatic, chemical or mechanical treatment. With the aim of utilizing cellulose nanofibrils (CNFs) from Oryza sativa, we isolated microcrystalline cellulose using the Kraft process, followed by...

Université de Fribourg

Li0.5Ni0.5Ti1.5Fe0.5(PO4)3/C electrode material for lithium ion batteries exhibiting faster kinetics and enhanced stability

Srout, Mohammed ; Kwon, Nam Hee ; Ben Youcef, Hicham ; Semlal, Nawal ; Fromm, Katharina M. ; Saadoune, Ismael

In: ACS Applied Materials & Interfaces, 2020, vol. 12, no. 16, p. 18496–18503

Natrium super ionic conductor (NASICON) materials providing attractive properties such as high ionic conductivity and good structural stability are considered as very promising materials for use as electrodes for lithium- and sodium-ion batteries. Herein, a new high-performance electrode material, Li0.5Ni0.5Ti1.5Fe0.5(PO4)3/C, was synthesized via the sol–gel method and was...

Université de Fribourg

Tautomerism and self-association in the solution of new pinene-bipyridine and pinene-phenanthroline derivatives

Solea, Atena B. ; Cornu, Ivan ; Deneva, Vera ; Crochet, Aurelien ; Fromm, Katharina M. ; Antonov, Liudmil ; Allemann, Christophe ; Mamula, Olimpia

In: Molecules, 2020, vol. 25, no. 2, p. 298

Two novel pinene-type ligands have been synthesized and their tautomeric and self-associating behavior studied in solution and in the solid state. The first ligand, an acetylated derivative of 5,6-pinene-bipyridine, displays keto-enol tautomerism in solution. This tautomeric equilibrium was studied by NMR and UV-Vis spectroscopy in various solvents, and the results were compared with the...

Université de Fribourg

Hierarchically porous reduced graphene oxide coated with metal–organic framework hkust-1 for enhanced hydrogen gas affinity

Song, Kyung Seob ; Kim, Daeok ; Coskun, Ali

In: ACS Applied Nano Materials, 2020, vol. 3, no. 2, p. 985–991

Metal–organic frameworks (MOFs) are crystalline porous materials that have been actively explored for various gas storage, separation, and conversion applications because of their structural tunability. While the micropores (<2 nm) in MOFs are essential for increased gas affinity, these small pores significantly decrease the mass-transport kinetics. One way to address this challenge is to ...