Experimental and theoretical investigations of positron trapping by disk shaped Guinier-Preston zones as appearing in AlCu alloys are performed. Using positron lifetime and angular correlation S-parameter measurements the decomposition phenomena are studied in an AI-1.9 at% Cu alloy. The energy and the wave function of a positron within a cylindrical shaped trap is calculated using Ritz's variational principle. Although a weak localization of the positrons by multilayer Guinier-Preston zones (GP zones) is to be expected from theory, the experimental spectra are dominated by positron annihilation in vacancies surrounded by Cu atoms. Above 200 "C positron trapping by semicoherent and incoherent precipitates is found.Es werden experimentelle und theoretische Untersuchungen des Positroneneinfangs durch scheibenformige Guinier-Preston-Zonen, wie sie in A1Cu-Legierungen auftreten, vorgenommen. Am Beispiel einer Al-1,9 at% Cu-Legierung werden die Entmischungsvorgange mittels Positronen-Lebensdauersowie Winkelkorrelations-S-Parameter-Messungen untersucht. Die Energie und die Wellenfunktion cines Positrons in einer zylinderformigen Haftstelle werden mit Hilfe des Ritzschen Variationsverfahrens berechnet. Obwohl ein Positroneneinfang durch die mehrschichtigen Guinier-Preston-Zonen theoretisch moglich ist, werden die Spektren durch Annihilationsakte in Leerstellen in kupferreicher Umgebung bestimmt. Oberhalb 200 "C wird ein Positroneneinfang durch semikoharente und inkoharente Ausscheidungen beobachtet.

Outcome of allogeneic stem cell transplantation (alloSCT) is hampered by substantial non-relapse mortality (NRM). Given its impact on organ function and immune response, the nutritional status has been suggested as relevant for NRM. We aimed to evaluate the association of NRM with nutritional status prior to alloSCT and in the post-SCT course. In a retrospective single-center study, we analyzed 128 alloSCTs. Besides standard characteristics, nutrition-associated parameters BMI, serum total protein, and serum albumin were recorded before conditioning and at various time points after alloSCT. Association with NRM was evaluated by univariate and multivariate survival analysis. The cohort comprised patients with a median BMI of 26 kg/m2 (16.7–46.9 kg/m2), median serum total protein of 59 g/l (41–77 g/l), and serum albumin of 36 g/l (22–46 g/l) before SCT. NRM at d+100 was 14.8% and at 1 year 26.6%. Prior to SCT, only serum albumin deficiency was associated with increased NRM (p = .010) in multivariate analysis. After SCT (d+30 and d+100), all nutrition-associated parameters decreased (p < .002), but no association of deteriorating nutritional status with NRM was found. In multivariate analysis, serum albumin (p = .03) and severe albumin deficiency (p = .02) correlated with NRM at d+30 and d+100, while BMI and serum total protein did not. In our study, albumin deficiency, particularly prior to alloSCT, shows a strong correlation with NRM. This finding may add to monitoring, risk evaluation, and counseling of patients and serve as a rational for interventions to improve the nutritional status in patients undergoing SCT.

Starting from a pseudopotential calculation for metallic beryllium the K-emission spectra of different polarizations, the Compton profiles for several directions, and the APS are calculated. Besides the shape of the emission spectra also the absolute values of the intensity are highly anisotropic due to the existence of localized charges along the hexagonal axis of Be. The calculated spectra agree well with a recently published measurement. The Compton profiles for three directions are Calculated in momentum approximation. The comparison of the anisotropies obtained with those of several measurements and a LCAO calculation shows a good conklation.Ausgehend von einer Pseudopotentialrechnung fur metallisches Beryllium werden die K-Emissionsspektren verschiedener Polarisationen, die Comptonprofile unterschiedlicher Richtungen sowie das AP-Spektrum berechnet. Neben der Form der Emissionsspektren ist auch die Absolutintensitiit wegen der Existenz lokalisierter Ladungen in Richtung der ~-~4 c h s e im Be stark anisotrop. Die berechneten Spektreii stehen im Einklang mit einer kurzlich veroffentlichten Messung. Die Comptonprofile werden fur drei Richtungen in Impulsniiherung berechnet. Der Vergleich der Anisotropien mit verschiedenen Messungen und einer LCAO-Rechnung zeigt eine sehr gute Ubereinstimmung. IntroductionBeryllium has some anomalous properties, for example, high Debye and melting temperatures, sound velocity, diamagnetic susceptibility, and electronic specific heat. Therefore, it has been the subject of many theoretical and experimental investigations during the last few years.Not only because of its properties but also due to its simple crystal structure (h.c.p.) and its atomic electron configuration there exist a lot of band-structure calculations.We intended to investigate spectroscopic properties of Be, closely connected to the band structure, by computing X-ray spectra and Compton profiles from the band structure and then comparing them with the experimental results.I n Section 2, X-ray emission spectra of single crystals are given. The K-emission spectrum of simple metals such as Be does not show significant peaks. Contrary to this, the polarized K-spectra of Be give far more information. Dropping the energy dependence of the matrix elements, such a polarized spectrum reflects the partial density of the occupied states of a certain magnetic quantum number.I n order to check the region above the Fermi level, we calculated the self-convolution of the unoccupied total density of states and compared this with an experimental AP spectrum in Section 3.Finally, in Section 4 the theoretical momentum distribution of single crystals is compared with Compton profiles for different directions of the scattering wave vector.The starting point of our calculations is the band structure of Be obtained by Taut [1]. From this calculation the energy values and the wave functions of the first 30 bands were available at a mesh of 222 points in 1/24 part of the Brillouin zone.

Intensities for polarized X-ray emission spectra are given by the elements of the density matrix expanded with respect to lattice harmonics. These intensities and densities of states for special values of the angular momentum and special representations of the point group are presented for Be, Mg, and Zn starting from a pseudopotential calculation. The energy dependence and the anisotropy of the radial integration is investigated. It is shown that the anisotropic spectra can be described excellently by located densities of states. Non-diagonal elements of the density matrix give the main contribution to the anisotropy of the LII, 111-spectrum of magnesium. The spectra are broadened and compared with experimental K-spectra. A good agreement is achieved, some discrepancy remains concerning the size of the anisotropy.Die Intensitaten polarisierter Rontgenemissionwpektren werden durch die Elemente der beziiglich der Gitterharmonischen entwickelten Dichtematrix dargestellt. Diese Intensitiiten und partielle Zustandsdichten zu speziellen Darstellungen der Punktgruppe des atomaren Platzes werden fiir Be, Mg und Zn aus einer Pseudopotentialrechnung gewonnen. Die Energieabhiingigkeit und die Anisotropy der radialen Integration werden untersucht. Es wird gezeigt, &I3 die anisotropen Spektren sehr gut durch lokalisierte Zustandsdichten beschrieben werden konnen. Die Anisotropie des LII, 111-Spektrums von Magnesium wird durch die Nichtdirtponalelemente der Dichtematrix bestimmt. Nach einer Faltung werden die Spektren mit experimentell gewonnenen K-Spektren verglichen. Es besteht eine gute Obereinstimmung, beziiglich der GroBe der Anisotropy treten noch Unterschiede auf.

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