Determination of the anharmonicity constant of oxygen by raman measurements

The hot band ν = 1 → 2 of O₂, which could not be resolved in previous Raman measurements, has been observed by direct scanning of the purely isotropic part of Raman scattered light. A computer simulation of the spectrum confirmed the set of anharmonicity constants given by Babcock and Herzberg.     

Untersuchungen an den freien Nucleotiden aus Hefe nach Gamma-Bestrahlung

Zusammenfassung Saccharomyces cerevisiae var. ellipsoideus wurde 0,3×10⁶ rad⁶⁰Co-Gammastrahlung ausgesetzt. Zu verschiedenen Zeiten nach der Bestrahlung wurde der Einbau von³²PO₄ ^3– in die freien Nucleotide untersucht. Die ausgeprägteste Veränderung gegenüber einer nichtbestrahlten Kontrolle war eine Abnahme der Menge und Radioaktivität von Adenosintriphosphat bei gleichzeitigem Anstieg von Adenosinmonophosphat. Auch bei Uridin-5-diphosphat-N-acetylglucosamin und Uridin-5-diphosphatmannose ergaben sich quantitative Verschiebungen.

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Saccharomyces cerevisiae var. ellipsoideus was gammairradiated at a dose of 0.3×10⁶ rad⁶⁰Co. At different times after irradiation the incorporation of³²PO₄ ^3– into the acid-soluble nucleotides was investigated. The most noticeable change with respect to a non irradiated control was the decrease in the quantity and radioactivity of adenosine triphosphate concomitant with an increase in adenosine monophosphate. A quantitative shift in the amounts of uridine-5-diphosphate N-acetyl-glucosamines and uridine-5-diphosphate mannose was also observed.

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Mit 5 Abbildungen     

Possibility of measuring multiply labelled samples by Cherenkov spectrometry

The activity of multiply labelled samples can be measured by the overlap technique on the basis of the Cherenkov effect only in the case of two or rarely three isotopes, having β-energies different enough. Though the colour filters change the shape of the energy spectra of β-isotopes, the overlap technique cannot be used more favourably. It is best to use the influence of filters on the efficiency. Measuring with and without filters, it is possible to determine the activity of two or three isotopes separately in one sample.     

Absolute determination of empty band dispersion in copper by momentum resolved Bremsstrahlung isochromat spectroscopy

Momentum resolved Bremsstrahlung isochromat spectra at $\text{H}\text{?}\text{ω = 9.7}\text{eV}$ from Cu(0 0 1) and Cu(0 1 2) surfaces are presented. Identifying the same direct interband transition into unoccupied final electronic states from the two crystal surfaces by energy coincidence we can locate the transition in k-space by triangulation. Our experimental results are compared to theoretical calculations.     

Structure of dislocation cores in the silicon crystal

We have recently produced a Lifson–Warshel force field for the silicon crystal. This field, that goes further than the harmonic approximation, is particularly adapted for the calculation of defect structures. It requires five free parameters, but one of them in the field already produced, the linear bending term, is significant for the perfect lattice structure only and should be eliminated in dealing with defect structures. Also, one of the fixed parameters can be adjusted to fit precisely the experimental value of the stacking fault energy. We show that an excellent fitting of the phonon dispersion curves, in the least squares sense, is obtained with the parameters thus changed. We illustrate the use of this field in discussing the problem of reconstruction of the 90° partial dislocation in silicon.     

COMPUTATIONAL MULTISCALE METHODS FOR LINEAR HETEROGENEOUS POROELASTICITY

We consider a strongly heterogeneous medium saturated by an incompressible viscous fluid as it appears in geomechanical modeling.This poroelasticity problem suffers from rapidly oscillating material parameters,which calls for a thorough numerical treatment.In this paper,we propose a method based on the local orthogonal decomposition technique and motivated by a similar approach used for linear thermoelasticity.Therein,local corrector problems are constructed in line with the static equations,whereas we propose to consider the full system.This allows to benefit from the given saddle point structure and results in two decoupled corrector problems for the displacement and the pressure.We prove the optimal first-order convergence of this method and verify the result by numerical experiments.