14 research outputs found
Absolute fraction of emitted Ps determined by GEANT4 supported analysis of gamma spectra
The fraction of positronium (Ps) emitted from a surface of a germanium single
crystal at high temperature is usually assumed to approach unity at zero
positron implantation energy. In the experiment, however, the determination of
the absolute Ps fraction is not straight forward since recording a reference
spectrum with Ps formation remains demanding. We use GEANT4-simulated
detector responses to and radiation sources mimicking
positron and Ps annihilation inside the (coincidence) Doppler-broadening
spectrometer at NEPOMUC, FRM II, in order to derive a reliable value for the Ps
fraction reemitted from a Ge(100) target heated close to its melting point.
Analysis of the measured spectra by fitting the simulated spectra shows an
absolute value of maximum Ps formation, contradicting the
assumption
Proteomics- and Metabolomics-Based Analysis of Metabolic Changes in a Swine Model of Pulmonary Hypertension
Tailoring the Oxygen Reduction Activity of Pt Nanoparticles through Surface Defects: A Simple Top-Down Approach
Impact of oxygen diffusion on superconductivity in YBa2Cu3O7−δ thin films studied by positron annihilation spectroscopy
The oxygen deficiency in YBaCuO (YBCO) plays a
crucial role for affecting high-temperature superconductivity. We applied
(coincident) Doppler broadening spectroscopy of the electron-positron
annihilation line to study in situ the temperature dependence of the oxygen
concentration and its depth profile in single crystalline YBCO film grown on
SrTiO (STO) substrates. The oxygen diffusion during tempering was found to
lead to a distinct depth dependence of , which is not accessible using
X-ray diffraction. A steady-state reached within a few minutes is defined by
both, the oxygen exchange at the surface and at the interface to the STO
substrate. Moreover, we revealed the depth dependent critical temperature
in the as prepared and tempered YBCO film
Effect of Rumen-Protected Methionine on Metabolic Profile of Liver, Muscle and Blood Serum Samples of Growing German Simmental Bulls Fed Protein-Reduced Diets
This study aimed to determine the metabolic response of growing German Simmental bulls fed rations low in crude protein (CP) supplemented with rumen-protected methionine (RPMET). In total, 69 bulls (on average 238 ± 11 days of age at start and 367 ± 25 kg of bodyweight) were assigned to three dietary treatments (n = 23/group): Positive control (CON; 13.7% CP; 2.11 g methionine/kg DM), negative control deficient in CP (RED; 9.04% CP; 1.56 g methionine/kg DM) and crude protein-deficient ration supplemented with RPMET (RED+RPMET; 9.04% CP; 2.54 g methionine/kg DM). At slaughter, samples of liver, muscle and blood serum were taken and underwent subsequent metabolomics profiling using a UHPLC-QTOF-MS system. A total of 6540 features could be detected. Twenty metabolites in the liver, five metabolites in muscle and thirty metabolites in blood serum were affected (p 0.05) due to dietary treatments. In total, six metabolites could be reliably annotated and were thus subjected to subsequent univariate analysis. Reduction in dietary CP had minimal effect on metabolite abundance in target tissues of both RED and RED+RPMET bulls as compared to CON bulls. The addition of RPMET altered the hepatic anti-oxidant status in RED+RPMET bulls compared to both RED and CON bulls. Results exemplify nutrient partitioning in growing German Simmental bulls: bulls set maintenance as the prevailing metabolic priority (homeostasis) and nutrient trafficking as the second priority, which was directed toward special metabolic functions, such as anti-oxidant pathways
Mechanical and morphological bond line properties of silver birch wood pretreated by aqueous extraction
While bonding for structural applications in Europe was limited to only a few softwood species in the past, forest alterations toward more climate stability will increase the diversity of tree species. This requires an understanding of typal wood-adhesive interactions. To help facilitate birch wood bonding, its cold-water soluble extractives and their effects on mechanical performance and bond line morphology were studied using water-borne melamine-urea-formaldehyde (MUF) and hydrophobic solvent-free polyurethane (PUR) adhesives. Extractives classes were identified via mass spectrometry and their concentration and extraction kinetics were evaluated. The analysis revealed that the mechanical properties of the bond line were essentially unaffected by extraction when using the hydrophobic PUR adhesive. Increased degrees of extraction resulted in reduced MUF penetration, and slightly thicker bond lines, however, the mechanical results indicate improved performance, indicating fewer defects in the cured adhesive network.</p