In: Review of Scientific Instruments, 2013, vol. 84, no. 9, p. 093104
We report on a high-resolution transmission-type curved crystal spectrometer based on the modified DuMond slit geometry. The spectrometer was developed at the University of Fribourg for the study of photoinduced X-ray spectra. K and L X-ray transitions with energies above about 10 keV can be measured with an instrumental resolution comparable to their natural linewidths. Construction details...
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In: Physical Chemistry Chemical Physics, 2013, vol. 15, no. 33, p. 13902–13910
Herein we present a Ligand Field Density Functional Theory (LFDFT) based methodology for the analysis of the 4fⁿ → 4fⁿ⁻¹5d¹ transitions in rare earth compounds and apply it for the characterization of the 4f² → 4f¹5d¹ transitions in the quantum cutter Cs₂KYF₆:Pr³⁺ with the elpasolite structure type. The methodological advances are relevant for the analysis and prospection of...
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In: Physical Review Letters, 2013, vol. 111, no. 3, p. 037201
Single phase and strained LuMnO₃ thin films are discovered to display coexisting ferromagnetic and antiferromagnetic orders. A large moment ferromagnetism (≈1μB), which is absent in bulk samples, is shown to display a magnetic moment distribution that is peaked at the highly strained substrate-film interface. We further show that the strain-induced ferromagnetism and the...
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In: Physical Review E, 2013, vol. 88, no. 4, p. 042303
We calculate tractable microscopic expressions for the low-shear normal-stress coefficients of colloidal dispersions. Although restricted to the low rate regime, the presented formulas are valid for all volume fractions below the glass transition and for any interaction potential. Numerical results are presented for a system of colloids interacting via a hard-core attractive Yukawa potential, for...
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In: The Journal of Chemical Physics, 2013, vol. 139, no. 10, p. 104108
We derive a dynamic Ornstein-Zernike equation for classical fluids undergoing overdamped Brownian motion and driven out of equilibrium. Inhomogeneous two-time correlation functions are obtained from functional differentiation of the one-body density and current with respect to an appropriately chosen external field. Functional calculus leads naturally to non-Markovian equations of motion for the...
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In: Physical Review B, 2013, vol. 88, no. 10, p. 104110
We have measured the temperature dependence of the direct band gap Eg in SrTiO₃ and BaTiO₃ and related materials with quantum-paraelectric and ferroelectric properties using optical spectroscopy. We show that Eg exhibits an anomalous temperature dependence with pronounced changes in the vicinity of the ferroelectric transition that can be...
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In: Superconductor Science and Technology, 2013, vol. 26, no. 9, p. 095008
In the present paper we report the effect of graphene oxide (GO) doping on the structural and superconducting properties of MgB₂. Bulk polycrystalline samples have been synthesized via a solid state reaction route with compositions MgB₂ + x wt% of GO (x = 0, 1, 2, 3, 5, 7 and 10) by sintering at ~850 ° C in a reducing atmosphere of Ar/H₂ (9:1). The x-ray diffraction...
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In: Physical Review B, 2013, vol. 88, no. 7, p. 075138
We address the question of the origin of the recently discovered chiral property of the charge-density-wave phase in 1T-TiSe₂, which so far lacks a microscopic understanding. We argue that the lattice degrees of freedom seem to be crucial for this novel phenomenon. We motivate a theoretical model that takes into account one valence and three conduction bands, a strongly screened Coulomb...
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In: Journal of Bacteriology, 2013, vol. 195, no. 18, p. 4274–4282
Motility of bacteria like Salmonella enterica is a highly regulated process that responds to a variety of internal and external stimuli. A hierarchy of three promoter classes characterizes the Salmonella flagellar system, and the onset of flagellar gene expression depends on the oligomeric regulatory complex and class 1 gene product FlhD4C2. The flhDC promoter is a target for a broad range of...
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In: Carbon, 2013, vol. 64, p. 45–60
Graphene-based nanomaterials are expected to have a profound impact on a broad range of applications. However, studies devoted to investigating the putative adverse health effects of these nanomaterials are hugely underrepresented in the current scientific literature. We have investigated the in vitro short-term cellular toxicity associated with graphene derivatives (GD): graphene oxide and...
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