Search results for "MINERALOGY"

Non-Matrix-Matched Calibration for the Multi-Element Analysis of Geological and Environmental Samples Using 200 nm Femtosecond LA-ICP-MS: A Compariso…

2014

LA-ICP-MS is one of the most promising techniques for in situ analysis of geological and environmental samples. However, there are some limitations with respect to measurement accuracy, in particular for volatile and siderophile/chalcophile elements, when using non-matrix-matched calibration. We therefore investigated matrix-related effects with a new 200 nm femtosecond (fs) laser ablation system (NWRFemto200) using reference materials with different matrices and spot sizes from 10 to 55 μm. We also performed similar experiments with two nanosecond (ns) lasers, a 193 nm excimer (ESI NWR 193) and a 213 nm Nd:YAG (NWR UP-213) laser. The ion intensity of the 200 nm fs laser ablation was much l…

Laser-ultrasonics: a non-contact method to link the acoustic attenuation to metal damping properties up to the melting point

2004

The objective of this work is to describe the viscoelastic behavior of metals up to their melting temperature by measuring the velocity and the attenuation of ultrasonics waves. For that purpose, a technique called laser-ultrasonics has been optimized for the high temperature domain and the solid to liquid transition. This paper is especially applied to the viscoelastic characterization of tin, from room temperature up to the melting point.

Etude theorique de la dynamique du réseau de batio en phase quadratique

1999

Abstract The lattice dynamics of barium titanate BaTiO 3 is discussed quantitatively in the framework of a shell model taking into account the electronic polarizabilities of the constituent ions and including Coulomb and short-range interactions. The results of calculations point out the important role of the anisotropic oxygen polarizability. There is a good agreement between calculated and experimental dispersion curves.

LIGAND FIELD CALCULATION FOR THE COMPLEX Fe(H2O)2+6 IN FROZEN AQUEOUS SOLUTION OF Fe(ClO4)2

1980

Modelling of light transmittance and reflectance in flat fluidized photoreactors

1992

In recent years several photon induced chemical reactions involving the use of a solid catalyst have been studied. Flat fluidized beds have proved to be promising devices for carrying out these photocatalytic reactions. There is therefore a need for the modelling of light interactions within such kinds of photoreactors. In this paper, a phenomenological model is proposed for simulating the light transmission and reflection in flat fluidized gas-solid photoreactors. A detailed description of the model is presented. The model predictions were compared with experimental data and a satisfactory agreement was found. Correlations were also suggested for the estimation of model parameters. Depuis …

Controls on lineation development in low to medium grade shear zones: a study from the Cap de Creus peninsula, NE Spain

2002

Lineations composed of similarly oriented elongate mineral aggregates or grains are a common feature in deformed rocks, but it is unclear which factors control the development of such lineations. Field observations and microstructural analysis of samples, which were taken from discrete greenschist to lower amphibolite facies shear zones of the easternmost Variscan Pyrenees, show that strain is only one of several factors that control the strength and type of a lineation. Dynamic recrystallization, metamorphic reactions and rigid body rotation are also important controlling factors for the development of lineations. The most important of these is dynamic recrystallization. The way in which d…

Shear sense indicators in striped bedding-veins

2000

Striped bedding-veins are veins that lie subparallel to bedding and have an internal layering or lineation at a small angle to the veins’ long axis. They form during bedding-parallel slip and can be used as shear sense indicators. Solid inclusion trails produce the visible internal layering or lineation and track the opening direction of the veins. Elongate quartz crystals however can be oriented at an angle of up to 80° to the opening direction, are non-tracking, and contain almost no information on the shear sense. The striped bedding-veins can be separated into three types according to the geometry of their internal segmentation. Veins of type B opened parallel to jogs oriented at a low …

Hydrothermal synthesis of zeolites from rhyolitic pumice of different geological origins

1983

Abstract Twelve samples of rhyolitic pumice from widely different origins were subjected to zeolitization in standard hydrothermal conditions (solid/liquid ratio, 1 5 ; T , 95°C; reaction time, 5 h; alkaline solution 5 N NaOH). The Si Al ratio of the starting material was of special importance in that zeolites formed with Si Al ratios similar to or smaller than that of the parent material. Pumice with low SiO 2 Al 2 O 3 , and high Fe content, preferentially gave rise to zeolites with lower SiO 2 Al 2 O 3 ratio than in the case of lower Fe and higher SiO 2 Al 2 O 3 ratio.

Gamma activity and geochemical features of building materials: estimation of gamma dose rate and indoor radon levels in Sicily.

2001

A high-purity germanium detector has been used to measure the abundance of radium (Ra), thorium (Th) and potassium (K) in building materials used in Sicilian dwellings. The measurements were performed to evaluate which material was suitable for the construction of an enclosure, which would have a low background emission. The materials examined in this work showed concentrations of 226Ra, 232Th and 40K dramatically variable depending on the lithologies, particularly in the case of blocks, sands and aggregates commonly used in building materials in Sicily. The results are discussed and a criterion is indicated to reduce the radiation dose to humans. Since radon inlet is a major health problem…

Periglacial transport distance of Pb derived from small-scale ore veins in the Rhenish Slate Mountains

2008

Abstract The spatial extent of metal contamination caused by small-scale ore veins is increased by periglacial solifluction. Our objectives were (1) to examine the spatial distribution of Pb in cover beds that migrated over Pb ore veins, (2) to calculate the transport distance of ore-derived Pb, and (3) to determine controls on the transport distance. We examined six transects (320–775 m long) in the Rhenish Slate Mountains in West Germany. The transects included four west-exposed and two east-exposed slopes with inclinations between 2–20°. All transects were forest-covered and located at 280–450 m above sea level. Soils were Dystric Cambisols and Stagnic Luvisols. Samples of 120 B horizons…