Identification of 180 million years old, probably unchanged melanine

The comparison of the infrared spectra of recent sepia melanine and of the content of the ink sac of fossilized cuttlefish indicates that the 180 million years old substance is unchanged melanine. Both substances behave identically on heating. Other procedures for identification of melanine are surveyed critically

Magnetic field-induced quantum critical point in YbPtIn and YbPt0.98_{0.98}In single crystals

Detailed anisotropic (H$\parallel$ab and H$\parallel$c) resistivity and specific heat measurements were performed on online-grown YbPtIn and solution-grown YbPt$_{0.98}$In single crystals for temperatures down to 0.4 K, and fields up to 140 kG; H$\parallel$ab Hall resistivity was also measured on the YbPt$_{0.98}$In system for the same temperature and field ranges. All these measurements indicate that the small change in stoichiometry between the two compounds drastically affects their ordering temperatures (T$_{ord}\approx3.4$ K in YbPtIn, and $\sim2.2$ K in YbPt$_{0.98}$In). Furthermore, a field-induced quantum critical point is apparent in each of these heavy fermion systems, with the corresponding critical field values of YbPt$_{0.98}$In (H$^{ab}_c$ around 35-45 kG and H$^{c}_c\approx120$ kG) also reduced compared to the analogous values for YbPtIn (H$^{ab}_c\approx60$ kG and H$^{c}_c>140$ kG

TRACE ANALYSIS OF ORGANIC COMPOUNDS

Abstract -The interest in organic trace analysis and its importance is demonstrated by a brief statistical review of the literature. The difficulties of organic trace analysis are compared to the complications found in inorganic trace analysis. There are numerous additional problems. Their solution calls for so much knowledge from neighbouring fields that organic trace analysis can be considered as an independent constantly expanding branch of analytical chemistry with many interdisciplinary connections

Sound-spelling units in German word identification. A developmental perspective

This dissertation explores the interaction of spoken and written language units in German word identification at different stages of reading proficiency, under consideration of cross-linguistic differences. The first part is based on a visual lexical decision experiment and a corpus study investigating the role of word stress in written word identification. Study 1 compares subjects’ responses to bisyllabic words with dominant vs. subdominant stress pattern. The results show that young readers tended to assign the most frequent stress pattern by default, whereas responses of adult participants did not reflect such a tendency. These observations indicate that word stress is automatically activated, at least in young readers from primary school. Study 2 investigates whether orthographic patterns present in word endings might provide cues to stress patterns in bisyllabic words, and the findings support this view. Considering observations from Study 1 and 2, it is argued that an implicit acquisition of orthographic cues to word stress through reading experience is a typical step in reading development, which is discussed within a recent model on polysyllabic word reading (Perry et al. 2010). The second part of this dissertation focuses on the role of orthographic information in spoken word identification. Study 3, an auditory lexical decision experiment compares subjects' responses to simplex words with sound-to-spelling consistent rimes vs. words with inconsistent rimes. The results show that words with inconsistent rimes were processed more slowly than words with consistent rimes even in young readers, thus indicating that spelling information is automatically activated in spoken word identification, already early in reading acquisition. Assumptions on the impact of spelling knowledge for the quality of lexically stored word representations is discussed, and it is argued that teaching methods should include implicit and explicit orthographic trainings from early on

Pressure-induced spin reorientation transition in layered ferromagnetic insulator Cr2Ge2Te6

Anisotropic magnetoresistance (AMR) of Cr2Ge2Te6 (CGT), a layered ferromagnetic insulator, is investigated under an applied hydrostatic pressure up to 2 GPa. The easy axis direction of the magnetization is inferred from the AMR saturation feature in the presence and absence of the applied pressure. At zero applied pressure, the easy axis is along the c-direction or perpendicular to the layer. Upon application of a hydrostatic pressure>1 GPa, the uniaxial anisotropy switches to easy-plane anisotropy which drives the equilibrium magnetization from the c-axis to the ab-plane at zero magnetic field, which amounts to a giant magnetic anisotropy energy change (>100%). As the temperature is increased across the Curie temperature, the characteristic AMR effect gradually decreases and disappears. Our first-principles calculations confirm the giant magnetic anisotropy energy change with moderate pressure and assign its origin to the increased off-site spin-orbit interaction of Te atoms due to a shorter Cr-Te distance. Such a pressure-induced spin reorientation transition is very rare in three-dimensional ferromagnets, but it may be common to other layered ferromagnets with similar crystal structures to CGT, and therefore offers a unique way to control magnetic anisotropy

Evaluation of EC Comparison on the Determination of 226Ra, 228Ra, 234U and 238U in Mineral Waters

This report describes all details of the comparison for the determination of 226Ra, 228Ra, 234U and 238U in mineral waters among 45 European laboratories monitoring radioactivity in food and the environment. Three commercially available mineral waters were provided as comparison samples. Reference values of the four radionuclides under study in this comparison were determined in collaborative work of IRMM and the Bundesamt für Strahlenschutz (BfS), using tracer techniques and standardised radionuclide solutions. The reference values are thus traceable to the SI units. The sample preparation and measurement processes applied in the participating laboratories are described and the results of the comparison are presented and discussed in detail. Whereas, in general, the measurement results for the uranium isotopes show a relatively favourable agreement with the reference value, the results of this comparison point at severe problems of 226Ra and 228Ra determination in about one fourth and more than one third of the laboratories, respectively. For radium, 19 results corresponding to 14 % of all are even off by a factor of two or more. By comparison, for uranium, this number amounts to 6 % (9 results out of 150). Nevertheless, also for the determination of uranium, 14 % to 23 % of the laboratories report results not compliant with the En evaluation criterion. The corresponding participants are urgently requested to investigate and revise their analytical methods.JRC.D.4-Nuclear physic

Mechanism of peptide-induced mast cell degranulation: translocation and patch clamp studies.

Substance P and other polycationic peptides are thought to stimulate mast cell degranulation via direct activation of G proteins. We investigated the ability of extracellularly applied substance P to translocate into mast cells and the ability of intracellularly applied substance P to stimulate degranulation. In addition, we studied by reverse transcription--PCR whether substance P-specific receptors are present in the mast cell membrane. To study translocation, a biologically active and enzymatically stable fluorescent analogue of substance P was synthesized. A rapid, substance P receptor- and energy-independent uptake of this peptide into pertussis toxin-treated and -untreated mast cells was demonstrated using confocal laser scanning microscopy. The peptide was shown to localize preferentially on or inside the mast cell granules using electron microscopic autoradiography with 125I-labeled all-D substance P and 3H-labeled substance P. Cell membrane capacitance measurements using the patch-clamp technique demonstrated that intracellularly applied substance P induced calcium transients and activated mast cell exocytosis with a time delay that depended on peptide concentration (delay of 100-500 s at concentrations of substance P from 50 to 5 microM). Degranulation in response to intracellularly applied substance P was inhibited by GDPbetaS and pertussis toxin, suggesting that substance P acts via G protein activation. These results support the recently proposed model of a receptor-independent mechanism of peptide-induced mast cell degranulation, which assumes a direct interaction of peptides with G protein alpha subunits subsequent to their translocation across the plasma membrane