Strangeness production in AA collisions at SIS18

Aluminium oxides doped with 1% ⁵⁷Fe were prepared by sol-gel method, and annealed for 3 hours at various temperatures between 550°C and 1100°C. Amorphous phases were obtained below 1000°C, and crystalline α–Al₂O₃ was formed at 1100°C. Although Al₂O₃ itself shows diamagnetism, the light doping of Fe ions into aluminium oxide induced a very weak ferromagnetism, but the ferromagnetism disappeared by longer annealing. M?ssbauer spectra were composed of paramagnetic Fe^2?+? and Fe^3?+? species for samples heated below 750°C, and of paramagnetic Fe^3?+? above 850°C, in addition to a magnetic sextet and relaxation peaks of Fe^3?+?. The magnetic and quadrupole interactions of the sextet and the relaxation peaks and the density functional calculations suggest that the lightly doped Fe^3?+? ions are substituted at Al sites in the Al₂O₃ lattice.     

Structure–conductivity relations of simulated highly porous nanoparticle aggregate films

Electrical conductivity of porous films composed of nanoparticle aggregates is theoretically evaluated with respect to aggregate structure and film packing density. The aggregates are fractals composed of 5–30 primary particles with diameter of 10 nm. The film properties are derived from simulated boxes in the range of 0.5–1 μm. The electrical conductivity across the films of packing densities ranging from 0.01 to 0.15 was studied. All films prepared by an aerosol deposition technique, which uses nanoparticle aggregates, exhibited percolation behavior between planes parallel to the moving direction of the aggregates. They also followed the classical percolation relation for electrical conductivity while the critical percolation packing density depends on the aggregate size and structure used to build the films. Films using larger aggregates as building blocks have higher electrical conductance than smaller aggregates close to the percolation limit. For validation and supplementary information, two independent models are developed: one model follows the percolation theory to get detailed physical insights and another one computes the exact conductivities but at the cost of some details. This analysis gives new insights into the conduction backbone structures of these films with regard to neck contacts within an aggregate and grain boundary contacts between aggregates. The results shown are important for solar application of these films and especially for gas sensors where high sensitivity is often counteracted by low conductivity.     

Spatial unmasking of nearby pure-tone targets in a simulated anechoic environment

Detection thresholds were measured for different spatial configurations of 500- and 1000-Hz pure-tone targets and broadband maskers. Sources were simulated using individually measured head-related transfer functions (HRTFs) for source positions varying in both azimuth and distance. For the spatial configurations tested, thresholds ranged over 50 dB, primarily as a result of large changes in the target-to-masker ratio (TMR) with changes in target and masker locations. Intersubject differences in both HRTFs and in binaural sensitivity were large; however, the overall pattern of results was similar across subjects. As expected, detection thresholds were generally smaller when the target and masker were separated in azimuth than when they were at the same location. However, in some cases, azimuthal separation of target and masker yielded little change or even a small increase in detection threshold. Significant intersubject differences occurred as a result both of differences in monaural and binaural acoustic cues in the individualized HRTFs and of different binaural contributions to performance. Model predictions captured general trends in the pattern of spatial unmasking. However, subject-specific model predictions did not account for the observed individual differences in performance, even after taking into account individual differences in HRTF measurements and overall binaural sensitivity. These results suggest that individuals differ not only in their overall sensitivity to binaural cues, but also in how their binaural sensitivity varies with the spatial position of (and interaural differences in) the masker.     

Der Nachweis des Eisens als Tri-n-butylammonium-eisen(III)-rhodanid

Ohne ZusammenfassungHierüber und über die quantitative Bestimmung des Eisens wird in Kürze berichtet.     

Identification of cis/trans isomers of methyl ester and oxazoline derivatives of unsaturated fatty acids using GC–FTIR–MS

Identification of cis/trans isomers of unsaturated fatty acids cannot usually be achieved by GC-MS (gas chromatography-mass spectrometry) without reference substances. In this study a GC-FTIR-MS system (gas chromatography-Fourier transform-mass spectrometry) was used to identify fatty acid methyl esters (FAMEs) and differentiate between the cis/trans isomers. Besides methyl esters, 2-alkenyl-4,4-dimethyloxazoline derivatives (DMOX), which have been used to locate double bond positions of unsaturated fatty acids, were examined with respect to their suitability for cis/trans differentiation. A combined GC-FTIR-MS system with a wide band (4000–550 cm^?1) mercury cadmium telluride (MCT) detector was used in series and parallel to identify 31 reference unsaturated fatty acids, including 7 pairs of cis/trans isomers. Serum samples of healthy persons and commercially available fish oil were analyzed as examples of complex mixtures. Using splitless injection the detection limit for the less sensitive IR detector was 25 ng/μl in case of the weak cis and trans bands. In the FTIR spectra cis/trans isomers were identified by analysis of bands arising from C? H out-of-plane (oop) bending: for both the FAME and DMOX derivatives cis-1,2-disubstituted double bonds give a strong band near 720 cm^?1 and the corresponding trans isomers near 967 cm^?1. cis Isomers could be identified further by a band at 3012 cm^?1. With the combined data of the GC-FTIR-MS system it is now possible to identify polyunsaturated fatty acids with regard to the discrimination of cis/trans isomers.     

Characterization of SiO2 protective coatings on polycarbonate

SiO₂ protective coatings have been deposited on polycarbonate substrates by plasma ion assisted deposition. The influence of ion energy on the water permeability and the surface topography of the coatings was studied by infrared spectroscopy and atomic force microscopy. Coatings deposited at sufficiently high ion energies show a barrier effect against moisture uptake and considerably reduced film roughness. Both effects are attributed to an increase of the packing densities of the coatings.     

Synthese von 2-methylalanin-peptiden,die pH-Abhängiggkeit ihrer 13C-NMR-spektren und eine neue methode zur auswertung über CS-diagramme

The uncommon amino-acid 2-methylalanine (α-aminoisobutyric acid, Aib) was investigated by ¹³C-NMR. The chemical shifts of amino- or carboxy-protected derivatives of Aib and of protected oligopeptides are discussed with respect to neighbouring groups and amino acids. The pH-dependence of the ¹³C-NMR spectra of Aib, Aib-Ala, Ala-Aib, Aib-Ala-Aib and Aib-Ala-Aib-Ala-Aib was studied. Using these examples, a new and advantageous method is demonstrated for the first time for the evalutions of NMR titration curves, which uses so-called chemical shift diagrams (CS diagrams).