Estudio sedimentológico preliminar y análisis de minerales pesados en la cueva Pocala

[Abstract] In 1999 two borings were performedin the area of Pocala Cave, one outside the cave and the other inside in the cave. In particular four samples of the first boring were studied.It seems that mineralogy is strictly connected with sedimentology where quartz and plagioclase are present. It could be a consequence of a periodical floods of flysch sediments during interglacial perio

The Stillwater Complex chromitites : the response of chromite crystal chemistry to magma injection

Nineteen chromite crystals from the A, B, E, G, H, J and K chromitite layers of the Peridotite Zone of the Stillwater Complex (Montana, USA) have been studied by means of X-ray single crystal diffraction and microprobe analyses. The results show that samples from the basal A layer are quite different from the others showing very high oxygen positional parameter u (0.2633-0.2635) and Ti- contents (0.059-0.067apfu). Mg# values are within the range 0.21-0.23 while for the other chromites it is in the range 0.45-0.47. Moreover, for the other samples, according to the structural parameters, two groups have been identified. The first one comprises samples of layers B, E and G, the second includes H, J and K layer samples. It is supposed that high Fe2+ and Ti contents of A layer samples are due to the post-crystallization reaction with interstitial liquid. This fact allowed a very slow cooling rate as evidenced by the high u values. The fractionation of evolved magma from within the intrusion and pulse of a new magma bringing more chromium into the chamber lead to Cr- and Fe3+ -rich compositions and consequently to the increase of the cell edges. The decrease of u values seems to be related to the Cr+Fe3+ and/or Al contents

X-ray computed microtomography of late copper age decorated bowls with cross-shaped foots from central Slovenia and the Trieste Karst (North-Eastern Italy): technology and paste characterization.

About 20 Late Copper Age bowls with cross-shaped foots from Deschmann\u2019s pile dwellings (Ljubljansko barje, central Slovenia) and Trieste Karst (North-Eastern Italy) have been investigated using X-ray computed microtomography (microCT) in order to study the vessel-forming technique, to characterise their pastes and to test the hypothesis that some Karst bowls could have been imported from nowadays central Slovenia or even more distant regions. In three selected virtual slices per sample, clay, lithic inclusions and pores have been segmented and quantified. In addition, the area, maximum length and width of each lithic inclusion have been calculated. Then, the microCT-derived results have been statistically analysed by principal component analysis (PCA). The orientation of pores and disjunctions in microCT volumes show that the basins of the bowls were built using mainly the coiling technique, while the base was shaped starting from a central piece, to which a layer of clay was added and then reshaped in order to produce the foots. The Slovenian bowls include both medium/coarse-grained and very fine- or fine-grained vessels mainly tempered with carbonate inclusions. The pastes of the Karst bowls are considerably heterogeneous. One bowl was most likely imported to the Karst but not from central Slovenia as it shows peculiar components, shape and decoration. The other two imported vessels show a very fine-grained paste comparable to the one of several samples from Deschmann\u2019s pile dwellings. Such technological similarity is confirmed by PCA of microCT data and petrographic observations. Our study confirms the existence of strong cultural connections between central Slovenia and the northernmost Adriatic coast during the Late Copper Age

A multi-analytical study of Bronze Age pottery from the UNESCO site of Al-Khutm (Bat, Oman)

The extensive investigation carried out in recent years at the UNESCO site of Al-Khutm (Ibri, Oman) has allowed to uncover the monumental remains of a tower dated back to the third millennium BC and to collect an abundant ceramic assemblage from the associated soil deposits. Eighteen selected pottery samples have been investigated using a multi-analytical approach including microfocus X-ray computed tomography, X-ray diffraction, optical microscopy and prompt gamma activation analysis to analyse the vessel-forming technique and to characterise their micro-structure, mineralogical and chemical composition to recognise possible local vs. non-local raw materials. The results provided new insights on ancient manufacturing processes and revealed that most of the vessels were locally produced exploiting raw materials from the surroundings of the site with the exception of a fragment of a black slipped jar. The chemical results suggest that the latter was imported from the Indus area in nowadays Pakistan. This evidence integrates our knowledge about the presence of this type of vessels in Oman and confirms the involvement of inland centres like Bat and Al-Khutm into a large-scale exchange system

Neurotransmitter selection by monoamine oxidase isoforms, dissected in terms of functional groups by mixed double mutant cycles

Double mutant cycles were constructed using neurotransmitters and synthetic substrates that measure their selective binding to one monoamine oxidase (MAO) enzyme isoform over another as a function of structural change. This work measures a reduction in selectivity for the MAOB isoform of 3 to 9.5 kJ mol−1 upon the addition of hydroxy functional groups to a phenethylamine scaffold. Replacement of hydroxy functional groups on the phenethylamine scaffold by hydrophobic substituents measures an increase in selectivity for MAOB of −1.1 to −6.9 kJ mol−1. The strategies presented here can be applied to the development of competitive reversible inhibitors of MAO enzymes and other targets with structurally related isoforms

Depression of glutamate and GABA release by presynaptic GABAB receptors in the entorhinal cortex in normal and chronically epileptic rats

Presynaptic GABAB receptors (GABABR) control glutamate and GABA release at many synapses in the nervous system. In the present study we used whole-cell patch-clamp recordings of spontaneous excitatory and inhibitory synaptic currents in the presence of TTX to monitor glutamate and GABA release from synapses in layer II and V of the rat entorhinal cortex (EC)in vitro. In both layers the release of both transmitters was reduced by application of GABABR agonists. Quantitatively, the depression of GABA release in layer II and layer V, and of glutamate release in layer V was similar, but glutamate release in layer II was depressed to a greater extent. The data suggest that the same GABABR may be present on both GABA and glutamate terminals in the EC, but that the heteroreceptor may show a greater level of expression in layer II. Studies with GABABR antagonists suggested that neither the auto- nor the heteroreceptor was consistently tonically activated by ambient GABA in the presence of TTX. Studies in EC slices from rats made chronically epileptic using a pilocarpine model of temporal lobe epilepsy revealed a reduced effectiveness of both auto- and heteroreceptor function in both layers. This could suggest that enhanced glutamate and GABA release in the EC may be associated with the development of the epileptic condition. Copyright © 2006 S. Karger AG

Crystal structure refinement of 13 olivines in the Forsterite-Fayalite series from volcanic rocks and ultramafic nodules.

2The results of the present paper confirm the overall dependence of the geometric parameters of olivines on the Mg/(Fe+Mn) ratio. M1 and M2 volumes linearly decrease with increasing forsterite (Fo) content but at different rates. The difference between the volumes of the octahedral sites decreases gradually fromFo 92% toFo 50% and then remains virtually constant down toFo 0.2%. Fe(M1)/Fe(M2) ratios indicate that Fe2+ prefers the M1 site in fayalite (Fa)-rich olivines (Fa=39% to 92%; average Fe(M1)/Fe(M2)=1.04±0.02). Instead, in Mg-olivines (Fo=80% to 92%) a Mg-M1 preference (average Mg(M1)/Mg(M2)=0.96±0.05) may exist. Finally, Mn(M1)/Mn(M2) ratios do not indicate a definite Mn preference for M2 in the studied olivines (MnO=0.44% to 4.5 wt.%; average Mn(M1)/Mn(M2)=0.99±0.13). No relevant influence on geometric parameters was observed between Ca-free and Cabearing (maximum CaO=0.66 wt.%) olivines.nonenonePrincivalle F.; Secco L.Princivalle, Francesco; Secco, L

Noduli ferrosi nelle grotte delle Valli del Natisone (Friuli)

In questo articolo vengono descritti i noduli ferrosi presenti nei sedimenti recenti delle grotte delle Valli del Natisone (Prealpi Giulie, Friuli orientale). Sulla base di osservazioni macroscopiche, microscopiche, mineralogiche e chimiche i noduli sono stati distinti in varie categorie per ognuna delle quali \ue8 stata supposta una genesi diversa. Vengono quindi proposti dei modelli per la loro formazione e crescita. In this article ferrous nodules of recent sediments from the Natisone Valley caves (Friuli, NE Italy) are described. According to macroscopic, microscopic, mineralogical and chemical observations, nodules have been subdivided into different categories. For each category a different origin has been supposed. Then some models for nodules\u2019 genesis and growth have been suggested