Two-dimensional wetting layer structures of reduced ternary oxides on Ru(0001) and Pt(111)

Long-range ordered structures of reduced oxide films with monolayer thickness derived from BaTiO3 and SrTiO3 on Ru(0001) and Pt(111) are investigated by scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). Upon ultrahigh vacuum annealing at 1100 K, a hexagonal phase is observed for BaTiO3 on Ru(0001), which forms similarly from SrTiO3 on Pt(111). At higher temperatures, a triangle–square tiling called σ-phase develops in the BaTiO3/Ru(0001) system, with a unit cell rotation of 15° against the Ru(0001) substrate. Furthermore, it is shown that this 15° rotated σ-phase also forms in the BaTiO3/Pt(111) system in addition to the already known 8° rotated σ-phase. The results emphasize a strong flexibility in the structural parameters of the reduced oxide wetting layers in response to the substrate interaction strength

Entwicklung eines Fischtests zur Erfassung von Stoffen mit endokrinen Wirkungen in Oberflaechengewaessern. Teilprojekt 3: Der neue Fischtest in der Gewaesserueberwachung durch eine Landesbehoerde Abschlussbericht

The aim of the presented study was to establish a method to detect estrogen-induced effects in the aquatic environment, basing on the determination of yolk-proteins in the blood of male or juvenile fish by gel electrophoresis (SDS-PAGE). The method is suitable for the use in routine testing of sewage treatment works (STW) effluents as well as monitoring of free living fish. Effects of 1 ng/L etylestradiol or 100 ng/L estradiol are reliably detectable. In surface waters no estrogen-induced effects could be found, whereas effluents of some industrial STWs showed a weak estrogenic effect. Histology of normal gonadal development of the test fish is compared to the situation after exposure to endocrine disrupters and to the gonadal development of roach caught in the wild. A method to detect effects on the gonadotropin mediated control of reproduction was tested within a monitoring programme. At certain locations a high degree of juvenile male perch showed gonadal hypertrophy (pubertas praecox). It could be shown by chemical analysis that the effects on perch were highly correlated with the tributyl tin (TBT) burden of the sediment from the respective location. Exposing small fish species to TBT in single compound studies confirmed the finding that TBT may act as an endocrine disrupter on vertebrates. (orig.)In der vorliegenden Studie wurde ein Verfahren zum Nachweis oestrogener Effekte in der aquatischen Umwelt etabliert. Die Methode basiert auf der Identifikation von Dotterproteinen im Blut maennlicher oder juveniler Fische mittels Gelelektrophorese und ist sowohl zum Einsatz in Monitoringprogrammen freilebender Fische als auch fuer die Routine der Abwasseruntersuchung nach DIN geeignet. Effekte von 1 ng/L Ethinyloestradiol und 100 ng/L Oestradiol sind sicher nachweisbar. Oestrogene Effekte von Oberflaechengewaessern wurden nicht gefunden, im Ablauf einzelner Industrieklaeranlagen war ein geringer oestrogener Effekt nachweisbar. Der Bericht enthaelt eine histologische Darstellung der Gonadenentwicklung der Versuchsfische insbesondere nach Exposition gegen endokrintoxische Stoffe. Die Gonadenhistologie von Rotaugen ist vergleichend dargestellt. Ein Verfahren zur Erfassung von Fremdstoffwirkungen auf die zentralnervoese Kontrolle der Fortpflanzung wurde im Monitoring erprobt. An Standorten mit einer erhoehten Belastung der Sedimente mit zinnorganischen Verbindungen trat bei maennlichen Barschen eine Pubertas praecox auf. Laborversuche mit Fischen belegen den Verdacht, dass sedimentgebundenes Tributylzinn diese Stoerung der Fortpflanzung bewirkt. (orig.)SIGLEAvailable from TIB Hannover: F01B1771+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Direct quantitative material decomposition employing grating-based X-ray phase-contrast CT

Abstract Dual-energy CT has opened up a new level of quantitative X-ray imaging for many diagnostic applications. The energy dependence of the X-ray attenuation is the key to quantitative material decomposition of the volume under investigation. This material decomposition allows the calculation of virtual native images in contrast enhanced angiography, virtual monoenergetic images for beam-hardening artifact reduction and quantitative material maps, among others. These visualizations have been proven beneficial for various diagnostic questions. Here, we demonstrate a new method of ‘virtual dual-energy CT’ employing grating-based phase-contrast for quantitative material decomposition. Analogue to the measurement at two different energies, the applied phase-contrast measurement approach yields dual information in form of a phase-shift and an attenuation image. Based on these two image channels, all known dual-energy applications can be demonstrated with our technique. While still in a preclinical state, the method features the important advantages of direct access to the electron density via the phase image, simultaneous availability of the conventional attenuation image at the full energy spectrum and therefore inherently registered image channels. The transfer of this signal extraction approach to phase-contrast data multiplies the diagnostic information gained within a single CT acquisition. The method is demonstrated with a phantom consisting of exemplary solid and fluid materials as well as a chicken heart with an iodine filled tube simulating a vessel. For this first demonstration all measurements have been conducted at a compact laser-undulator synchrotron X-ray source with a tunable X-ray energy and a narrow spectral bandwidth, to validate the quantitativeness of the processing approach