Zur hydrogeologischen Interpretation von Isotopendaten im Zusammenhang mit Stofftransportprozessen

The migration of radionuclides and other tracers in porous layers is determined by substance transport. The physical and hydraulic basis of retardation is investigated. A definition of a factor of retardation is given, describing the ratio between the pore velocity of the water and the velocity of tracer migration. Consequences to the groundwater protection are discussed.     

Oxygen deficiency in oxide films grown by PLD

The incorporation of oxygen atoms in oxide films grown by pulsed laser deposition depends upon the oxygen pressure and laser power density. By carefully controlling these two parameters it is possible to control the oxygen deficiency in the samples, and thus to change their physical properties from insulating and transparent to absorbing and conducting. By using X-ray diffraction, Rutherford backscattering spectroscopy and resistivity measurements, we show that depending upon the oxide materials oxygen deficiency in the films can induce either the growth of stable sub-oxide phases or the formation of nanocomposite films by phase separation. The first case corresponds to oxides with a mixed valency cation like Ti, which leads to the formation of stable, crystalline and highly conductive TiO_x sub-oxide phases. The second case is well described by the indium tin oxides (ITO) in which a large oxygen deficiency leads to metallic clusters embedded into a stoichiometric matrix, i.e. nanocomposite films. This phenomenon is due to the fact that sub-oxides of these compounds are not stable and thus the oxygen deficiency induced a phase separation.     

Structure analysis of soluble proteins using electron crystallography

Electron crystallography as a structural determination technique has grown dramatically in use over recent years. Improvements in microscopes, equipment, practical techniques, computation facilities and image processing methods are reflected in the increasing number of near-atomic resolution structures that have been published.In this review we shall summarize the techniques involved in structure determination of soluble proteins using electron crystallography. Many soluble protein structures have been investigated in this manner over the past two decades. Here we present several examples where a variety of approaches have been used to gradually increase the information obtained.     

Improved branching ratio measurement for the decay K(0)(L) --> &mgr;(+)&mgr;(-)

We report results from Experiment 871, performed at the BNL AGS, of a measurement of the branching ratio K(0)(L)-->&mgr;(+)&mgr;(-) with respect to the CP-violating mode K(0)(L)-->pi(+)pi(-). This experiment detected over 6200 candidate &mgr;(+)&mgr;(-) events, a factor of 6 more than that seen in all previous measurements combined. The resulting branching ratio gamma(K(0)(L)-->&mgr;(+)&mgr;(-))/gamma(K(0)(L)-->pi(+)pi(-)) = (3. 474+/-0.057)x10(-6) leads to a branching fraction B(K(0)(L)-->&mgr;(+)&mgr;(-)) = (7.18+/-0.17)x10(-9), which is consistent with the current world average, and reduces the uncertainty in this decay mode by a factor of 3.     

Two-particle rapidity correlations in proton-nucleus interactions at 300 GeV

The single- and two-particle inclusive rapidity distributions for proton-nucleus interactions at 300 GeV in nuclear emulsions are presented. The analysis of the data with the two-particle rapidity correlation function R(ν₁, ν₂) shows clear evidence of short range correlations. A remarkable asymmetry between projectile and target hemisphere is found.     

Eulogy for Professor Mirka Miller (1949–2016)

The CIMPA Research School on Mathematical Models for Security Applications was dedicated to the memory of Emeritus Professor Mirka Miller, who suggested that it be held in Havana. Mirka Miller, member of the editorial board of Mathematics in Computer Science, devoted her research to Graph Theory and Data Security, fields where she made important and beautiful contributions.     

Erfahrungen und Ergebnisse der Isotopenanwendung im Industriezweig Braunkohle

This paper presents results of a study carried out in order to assess the applicability of ³²Si for groundwater dating. Measurements of ³²Si in soil samples of the unsaturated zone, of drainage waters and plant material give a basis for estimating the ³²Si initial concentration in groundwater. Different aquifers with groundwater of young and moderate ages have been selected for groundwater studies. For obtaining independent age information tritium was found to be a suitable reference isotope. A quantitative interpretation of the ³²Si data is generally complicated by geochemical processes, preferably in the unsaturated zone. Favourable conditions concerning the use of ³²Si in hydrogeology seem to exist in phreatic sandy aquifers, in limestone aquifers, and, depending on the thickness and composition of the unsaturated zone, in sandstone aquifers. Further improvements of the ³²Si method needs a better understanding of the geochemical processes affecting this isotope.     

Eine Apparatur zur Messung natürlicher 4C-Aktivitäten

Aufbau, Arbeitsweise und Eigenschaften einer Apparatur, mit der naturliche ^l4C-Aktiviäten in Grund- und Oberflächenwässern gemessen werden können, werden beschrieben.

Die Messung erfordert 3 Arbeitsschritte: Probenahme, Synthese von Benzol, welches dann den Probenkohlenstoff enthält, und Messung der ¹⁴C-Aktivität in einem Flüssigkeitsszintillationszähler.

Die Apparatur kann zur Datierung von Wasserproben im Altersbereich zwischen 200 und 37000 a verwendet werden.     

Topotactic insertion of lithium in the layered structure Li4VO(PO4)2: The tunnel structure Li5VO(PO4)2

A new V(III) lithium phosphate Li₅VO(PO₄)₂ has been synthesized by electrochemical insertion of lithium into Li₄VO(PO₄)₂. This phase, which crystallizes in the space group I4/mcm, exhibits a tunnel structure closely related to the layered structure of Li₄VO(PO₄)₂ and to the tunnel structure of VO(H₂PO₄)₂. The topotactic reactions that take place during lithium exchange and intercalation, starting from VO(H₂PO₄)₂ and going to the final phase Li₅VO(PO₄)₂ are explained on the basis of the flexible coordinations of V⁴⁺ and V³⁺ species. The electrochemical and magnetic properties of this new phase are also presented and explained on the basis of the structure dimensionality.