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Université de Fribourg

New safety-catch photolabile protecting group

Riguet, Emmanuel ; Bochet, Christian G.

In: Organic Letters, 2007, vol. 9, no. 26, p. 5453 -5456

Photolabile protecting groups have proven their usefulness on many occasions. Their versions as linkers are however less attractive, as robustness and real orthogonality become critical issues. Safety-catch systems, where a preliminary activation phase is necessary, circumvent the problem of premature cleavage. In this work, we introduce a new safety-catch photolabile protecting group, whose...

Université de Fribourg

Low-lying resonances in electron-argon scattering: Measurements at 5-meV resolution and comparison with theory

Franz, K. ; Hoffmann, T. H. ; Bömmels, J. ; Gopalan, A. ; Sauter, G. ; Meyer, W. ; Allan, Michael ; Ruf, M.-W. ; Hotop, H.

In: Physical Review A, 2008, vol. 78, no. 1, p. 012712

Combining a laser photoelectron source with a triply differentially pumped supersonic beam target and several electron multipliers for simultaneous detection of electrons elastically scattered into the angles 22.5°, 45°, 90°, 112.5°, and 135° and of metastable atoms due to inelastic scattering, we have carried out an improved study of electron-argon scattering over the energy range...

Université de Fribourg

C4-bound imidazolylidenes: from curiosities to high-impact carbene ligands

Albrecht, Martin

In: Chemical Communications, 2008, p. 3601-3610

This feature article summarizes the progress achieved thus far in using C4-bound imidazolylidenes as a new class of ligands for transition metals. Since the discovery of this unusual carbene bonding mode in 2001, various rational routes towards complexes containing C4-bound carbenes have evolved. These advances allowed for studying the impact of this new type of ligand on the transition metal...

Université de Fribourg

Combined rather than separate pathways for hedonic and sensory aspects of taste in fly larvae ?

Colomb, Julien ; Stocker, Reinhard F.

In: Fly, 2007, vol. 1, no. 4, p. 232 - 234

In mammals, the hedonic aspects (good versus bad) and sensory aspects (i.e., the molecular quality) of taste are associated with different brain regions. Anatomical data argue against such a separation in the primary taste center of Drosophila larvae. Is only one aspect of taste represented or do both co-exist at the same location? I present evidence for a hedonic representation in the larval...

Université de Fribourg

Classical biological control: exploiting enemy escape to manage plant

Müller-Schärer, Heinz ; Schaffner, Urs

In: Biological Invasions, 2008, vol. 10, no. 6, p. 859-874

Practitioners of classical biological control of invasive weeds are confronted with a dual expectation: to achieve successful control of plant invaders and to avoid damage to nontarget plants and adverse indirect effects. In this paper we discuss key issues that we consider to be crucial for a safe, efficient, and successful classical biological control project, and that have also caused some...

Université de Fribourg

Hydrogen storage properties of Mg[BH₄]₂

Matsunaga, Tomoya ; Buchter, Florian ; Mauron, Phillipe ; Bielmann, Michael ; Nakamori, Y. ; Orimo, S. ; Ohba, N. ; Miwa, K. ; Towata, S. ; Züttel, Andreas

In: Journal of Alloys and Compounds, 2008, vol. 259, no. 1-2, p. 583-588

Among the large variety of possible complex hydrides only few exhibit a large gravimetric hydrogen density and stability around 40 kJ mol⁻¹H₂. Mg[BH₄]₂ is based on theoretical approaches a complex hydride with an equilibrium hydrogen pressure of approximately 1 bar at room temperature and a hydrogen content of 14.9 mass%. The reaction of Li[BH₄] with MgCl₂ at elevated temperatures...

Université de Fribourg

Note on two-phase phenomena in financial markets

Jiang, Shi-Mei ; Cai, Shi-Min ; Zhou, Tao ; Zhou, Pei-Ling

In: Chinese Physics Letters, 2008, vol. 25, no. 6, p. 2319-2322

The two-phase behaviour in financial markets actually means the bifurcation phenomenon, which represents the change of the conditional probability from an unimodal to a bimodal distribution. We investigate the bifurcation phenomenon in Hang–Seng index. It is observed that the bifurcation phenomenon in financial index is not universal, but specific under certain conditions. For Hang–Seng index...

Université de Fribourg

Correlated roughness in polymer films containing Maghemite nanoparticles

Kashem, M. M. Abul ; Perlich, J. ; Schulz, Leander ; Roth, S. V. ; Müller-Buschbaum, P.

In: Macromolecules, 2008, vol. 41, no. 6, p. 2186 -2194

Two different uniform thicknesses (8 and 68 nm) of a nanocomposite film comprising diblock copolymer matrix and magnetic nanoparticles filler have been installed in one sample preparation step under identical condition simultaneously. Long-range interface correlations are investigated. Maghemite (F₂O₃) nanoparticles covered with polystyrene chains are incorporated in...

Université de Fribourg

Cobalt substituted ZnO thin films: a potential candidate for spintronics

Bhatti, Kanwal Preet ; Malik, Vivek Kumar ; Chaudhary, Sujeet

In: Journal of Materials Science: Materials in Electronics, 2008, vol. 19, no. 8-9, p. 849-854

Cobalt doped zinc oxide thin films have been deposited using spray pyrolysis method. These single phasic films exhibited [100] preferential texture and small decrease in the lattice parameter on cobalt substitution. The films having different Co concentration have almost similar surface morphology and microstructure. These Zn1−xCoxO (x ≤ 0.10) thin...