Electronic structures of PrBa₂Cu₃O₇, Pr₂Ba₄Cu₇O_15−y (y = 0, 1), and PrBa₂Cu₄O₈ based on LSDA + U method

Abstract

Scharf begrenzt: Eine räumlich hochaufgelöste Transgenexpression in zwei biologischen Anwendungen belegt das Potenzial einer Methode zur photoaktivierten Genexpression auf Grundlage eines photoempfindlichen Doxycyclinanalogons. Die Bestrahlung einer Hälfte eines transgenen Tabakblattes erzeugt eine scharf begrenzte Reportergenexpression im photoaktivierten Gewebe.

High-temperature crystal structure and transport properties of the layered cuprates Ln2CuO4, Ln=Pr, Nd and Sm

“…The oxygen diffusion coefficient D T and the surface exchange coefficient k for Pr 2 CuO 4 were determined by the isotopic exchange depth profile (IEDP) technique using SIMS after isotopic exchange of 18 O for 16 O in the ceramic samples.…”

“…Prior to 18 O exchange annealing, samples were held at 973, 1073, 1123 and 1173K in air of normal isotopic abundance for a period of time approximately one order of magnitude longer then the tracer annealing time. This was carried out to ensure that the material was in chemical equilibrium at the desired temperature and oxygen partial pressure (in this study all annealings…”

“…The air was then removed, and labeled oxygen (95% enriched 18 O 2 ) introduced. Annealing time was 10-12 minutes for the samples studied at 1073, 1123 and 1173 and 9 hours for 973K.…”

“…As an example, the 18 O isotopic concentration depth profile of Pr 2 CuO 4 annealed at 1073K is given in Fig. 7.…”

“…For Pr 2 CuO 4 we have also determined oxygen trace diffusion and surface exchange coefficients using the diffusion of the isotope 18 O detected by secondary ion mass spectrometry (SIMS). Phase purity of the compounds was checked by X-ray powder diffraction (XRD) recorded in Huber G670 Guinier diffractometer (CuKα1 radiation, image foil detector).…”