On the crystal lattice parameters of graphite-like phases of the B-C system

The structure of graphite-like BCx phases (x = 1, 1.5, 3, 4, 32) has been studied using conventional X-ray diffraction. The results have been obtained, which unambiguously point to turbostratic (one- dimensionally disordered) structure of all phases under study. The crystal lattice parameters, sizes of coherent scattering domains, and microstrain values have been defined, which have allowed us to find a correlation between the structure and stoichiometry of the phases synthesized at the same temperature

Clay mineralogy and magnetic susceptibility of Oxisols in geomorphic surfaces

Studies analyzing the variability of clay minerals and magnetic susceptibility provide data for the delineation of site-specific management areas since many of their attributes are important to agronomy and the environment. This study aimed to evaluate the spatial variability of clay minerals, magnetic susceptibility, adsorbed phosphorus and physical attributes in Oxisols of sandstones in different geomorphic surfaces. For that purpose, soil samples were collected every 25 m along a transect located within the area where the geomorphic surfaces were identified and mapped. The transect occupied the central portion of 500 ha, where it was also sampled for density purposes with one sample per six hectares. Soil samples were collected at a depth of 0.0-0.2 m. The results of the physical, chemical, mineralogical and magnetic susceptibility analyses were subjected to statistical and geostatistical analyses. The nature of the clay minerals and magnetic susceptibility was dependent on the variation of the soil parent material. High values of magnetic susceptibility were associated with the presence of maghemite and magnetite of coarse size. The spatial variability of crystallinity and the content of Fe oxides, as well as magnetic susceptibility, were dependent on the age of the geomorphic surfaces. The youngest surface had greater spatial variability of these attributes. The iron (goethite and hematite) and aluminum (gibbsite) oxides in the youngest geomorphic surface influenced the low values of soil density and high values of total pore volume, micropores and P adsorption. The characterization of the spatial variability of Fe oxides and susceptibility allowed for the delineation of homogeneous areas

Zum Test von Mikroprozessoren mit Pseudozufallsfolgen

Available from TIB Hannover: DB 4252 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Kontrolle von Stand und Fortschritt einer biologischen Sanierung NAPL-kontaminierter Boeden ueber die Bestimmung der Radonkonzentration in der Bodenluft Schlussbericht

Some methods for recycling of soil which is contaminated with hydrocarbons like petrol or diesel are based on the admixture of active biological material in order to reduce the contamination. This mixture is stored on a dump for some months and the reduction of the contamination is checked by regular chemical analysis of some samples. Task of the research project is to replace these analysis by an investigation of Radon gas, which is present in the pore volume of the dumped soil. In two series of experiments at dumps with contaminated soil biologically treated, an increase of radon concentration in conjunction with a decrease of contamination was detected. But the recorded change of Radon was much less than expected and shows a significant dependence on environmental parameters like temperature or soil structure. At the present state of development the method is not yet suitable to replace conventional analysis during soil recycling. (orig.)In einigen Verfahren zum Recycling von Boeden, die mit Kohlenwasserstoffen wie Benzin oder Diesel kontaminiert sind, wird dem Bodenaushub biologisch aktives Material zum Abbau der Kontamination zugesetzt und die Mischung mehrere Monate als Halde gelagert. Der dabei stattfindende Abbau der Kontamination wird mittels regelmaessiger chemischer Analyse einzelner Proben ueberwacht. Ziel der Untersuchungen ist es, diese Analysen durch eine Untersuchung des in dem Porenvolumen der Halde befindlichen Gases Radon zu ersetzen. In zwei Versuchsreihen an Halden aus biologisch beleten kontaminierten Boeden konnte ein Anstieg der Radonkonzentration bei fortschreitendem Abbau der Kontamination nachgewiesen werden. Die festgestellten Aenderungen der Radongehalte unterschritten die erwartete Groessenordnung und zeigten zudem eine deutliche Abhaengigkeit von den Umgebungsparametern wie z.B. der Temperatur sowie den strukturellen Eigenschaften des vorliegenden Bodens. Mit dem vorliegenden Entwicklungsstand ist die Methode noch nicht geeignet in dem Recyclingprozess konventionelle Analysen zu ersetzen. (orig.)Available from TIB Hannover: F01B1550+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman