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Heteroepitaxial iridium thin films were deposited on (0001) sapphire substrates by means of molecular beam epitaxy, and subsequently, one monolayer of graphene was synthesized by chemical vapor deposition. The influence of the growth parameters on the quality of the Ir films, as well as of graphene, was investigated systematically by means of low energy electron diffraction, x-ray reflectivity, x-ray diffraction, Auger electron spectroscopy, scanning electron microscopy, and atomic force microscopy. Our study reveals (111) oriented iridium films with high crystalline quality and extremely low surface roughness, on which the formation of large-area epitaxial graphene is achieved. The presence of defects, like dislocations, twins, and 30° rotated domains in the iridium films is also discussed. The coverage of graphene was found to be influenced by the presence of 30° rotated domains in the Ir films. Low iridium deposition rates suppress these rotated domains and an almost complete coverage of graphene was obtained. This synthesis route yields inexpensive, air-stable, and large-area graphene with a well-defined orientation, making it accessible to a wider community of researchers for numerous experiments or applications, including those which use destructive analysis techniques or irreversible processes. Moreover, this approach can be used to tune the structural quality of graphene, allowing a systematic study of the influence of defects in various processes like intercalation below graphene. [ABSTRACT FROM AUTHOR]

We present surface X-ray diffraction and fast scanning tunneling microscopy results to elucidate the nature of the surface phase transition on magnetite (001) from a reconstructed to a non-reconstructed surface around 720 K. In situ surface X-ray diffraction at a temperature above the phase transition, at which long-range order is lost, gives evidence that the subsurface cation vacancy reconstruction still exists as a local structural motif, in line with the characteristics of a 2D second-order phase transition. Fast scanning tunneling microscopy results across the phase transition underpin the hypothesis that the reconstruction lifting is initiated by surplus Fe ions occupying subsurface octahedral vacancies. The reversible near-surface iron enrichment and reduction of the surface to stoichiometric composition is further confirmed by in situ low-energy ion scattering, as well as ultraviolet and X-ray photoemission results.

Background: Chronic hyponatremia is common and associated with increased morbidity and mortality. However, whether treatment improves outcome in patients without significant symptoms is unclear. We here assessed the therapeutic outcome on clinical symptoms, neurocognitive and neuromuscular function in patients with chronic non profound hyponatremia., Material and Methods: Prospective case-control study in 19 patients from the University Hospital Würzburg with chronic non profound hyponatremia without clinically apparent symptoms. At baseline and after a 14-day treatment period of hyponatremia, patients were assessed by specific clinical symptoms questionnaire, neurocognitive and neuromuscular function was analysed by five attention tests and a gait test consisting of 3 steps "in tandem." The results were compared to a control group of healthy volunteers., Results: Compared to healthy volunteers, patients with mild (n = 10, mean serum sodium 132 ± 1.2 mmol/L) and moderate hyponatremia (n = 9, mean 126 ± 3.3 mmol/L) performed significantly worse in the neurocognitive subtests alertness (P = 0.018), divided attention (P = 0.017) and go/no-go (P = 0.026). Performance in the neuromuscular subtests was also lower in the patient group without reaching significance. The extent of hyponatremia had no impact on the specific test and questionnaire results. Fourteen-day treatment of hyponatremia improved clinical symptoms in all patients (P = 0.003) and neurocognitive function in sodium-normalised patients (go/no-go test, P = 0.029)., Conclusion: Chronic hyponatremia is symptomatic and impairs neurocognitive and neuromuscular function. Short-time therapeutic intervention led to improved clinical symptoms and neurocognitive function, but had no effect on neuromuscular function. Larger trials with long-term treatment are needed to specify the therapeutic need in chronic hyponatremia., (© 2018 Stichting European Society for Clinical Investigation Journal Foundation.)

A simple experiment to characterize the gating properties of X-ray area detectors using pulsed X-ray sources is presented. For a number of time-resolved experiments the gating uniformity of area detectors is important. Relative gating delays between individual modules and readout chips of PILATUS2 series area X-ray detectors have been observed. For three modules of a PILATUS 300K-W unit the maximum gating offset between the modules is found to be as large as 30 ns. On average, the first photosensor module is found to be triggered 15 ns and 30 ns later than the second and the third modules, respectively.