Measurement of calcite crystallographic-preferred orientations by magnetic anisotropy and comparison to diffraction methods

The anisotropy of magnetic susceptibility (AMS) of rocks reflects the preferred orientations of minerals. Therefore AMS is a quick and easy way to characterize rock fabrics (Hrouda 1982,Borradaile 1988); the obtained result is also called the magnetic fabric of the rock. The method has been often used to measure the orientation of ferromagnetic minerals, mainly magnetite, but in recent studies it has been increasingly used to measure textures of paramagnetic minerals as phyllosilicates (Lüneburg et al. 1999, Cifelli et al. 2004). A further application is the measurement of diamagnetic textures, especially calcite textures. Calcite is suitable for the AMS method, because it has a high magnetic anisotropy with the minimum susceptibility along the crystallographic c-axis. Therefore a preferred orientation of the c-axes, which can be induced by deformation, generates a magnetic fabric...conferenc

Non-Newtonian rheology of crystal-bearing magmas and implications for magma ascent dynamics

The eruptive dynamics of volcanic systems are largely controlled by the viscosity of deforming magma. Here we report the results of a series of high-temperature, high-pressure experiments at conditions relevant for volcanic conduits (250 MPa confining pressure and temperature between 500 °C and 900 °C) that were undertaken to investigate the rheology of magma with crystal fractions varying between 0.5 and 0.8 (50 to 80 wt.%) at different strain-rate conditions. The experiments demonstrate that the presence of crystals increases the relative viscosity (ratio between the viscosity of the mixture and the viscosity of the melt phase) of magmas and additionally induces a decrease of the relative viscosity with increasing strain-rate (shear thinning, non-Newtonian behavior). The experimental results, combined with existing data at low crystal fractions (0–0.3), were used to develop a semi-empirical parameterization that describes the variations of relative viscosity for crystal fractions between 0 and 0.8 and accounts for the complex non-Newtonian rheology of crystal-bearing magmas. The new parameterization, included into numerical models simulating the magma ascent dynamics, reveals that strain-rate-dependent rheology significantly modifies the dynamic behavior inside volcanic conduits, particularly affecting the magma fragmentation conditions

Experimental study of CO2 sequestration by ECBM recovery: the case of Sulcis coal.

An ECBM (Enhanced Coal Bed Methane) feasibility study started for the Sulcis Coal Province (SW Sardinia, Italy) in December 2004: geochemical, structural-geology, stratigraphic and reservoir engineering considerations are discussed. The first newly gathered experimental data are discussed, including: fluid geochemistry (major and minor elements, dissolved gases, C and He isotopic ratios) of the reservoir, coal composition and experimental data on CO2/CH4 adsorption on coal. A MapInfo GIS structure was built up including stratigraphical, geo-structural, hydrogeochemical, coal-compositional and environmental impact information as well as the CO2 sources location and typology. Even if these data could be preliminary with respect to the coal characteritics effectively located at the future injection depth, they highlighted both the challenging positive and negative aspects of the Sulcis Coal Province versus the exploitation of the ECBM technique. The most important objective of this phase I of the project is the selection of the best Sulcis ECBM test-pilot site, which will be followed (Phase II) by the choice of a scaled up site and possibly by a future network (Phase III). These phases are foreseen to be accompanied by the selection of progressively added CO2 industrial sources, to be used within the project economic spreadsheet model, actually in evolution. CO2 geological storage and CH4 production potentials in Sulcis have been grossly evaluated as a whole, in the frame of the Sardinia region CO2 sources, including the coal-fired power plants, both existent and foreseen (hundreds of millions of tonns of CO2 are possible to be stored underground in the next decades). The reservoir estimates, both for the CO2 injection and for the CH4 production are clearly involving to start the test-site phase exploitation, in the frame of an auspicabile international operative project

New insights into the mutable collagenous tissue of Paracentrotus lividus : preliminary results

The mechanically adaptable connective tissue of echinoderms (Mutable Collagenous Tissue\u2014MCT), which can undergo drastic nervously-mediated changes in mechanical properties, represents a promising model for biomaterial design and biomedical applications. MCT could be a source of, or an inspiration for, new composite materials whose molecular interactions and structural conformation can be changed in response to external stimuli. MCT is composed mostly of collagen fibrils, comparable to those of mammals, plus a variety of other components, including other fibrillar structures, proteoglycans and glycoproteins. This contribution presents the preliminary results of a detailed analysis of MCT components in the sea-urchin Paracentrotus lividus, focusing on biochemical characterization of the fibrils and biomolecular analysis of the presumptive glycoproteins involved. The final aims will be to confirm the presence and the role of these glycoproteins in echinoids and to manipulate simpler components in order to produce a composite with mutable mechanical properties

The propagation and seismicity of dyke injection, new experimental evidence

To reach the surface, dykes must overcome the inherent tensile strength of the country rock. As they do, they generate swarms of seismic signals, frequently used for forecasting. In this study we pressurize and inject molten acrylic into an encapsulating host rocks of (1) Etna basalt and (2) Comiso limestone, at 30 MPa of confining pressure. Fracture was achieved at 12 MPa for Etna basalt and 7.2 MPa for Comiso limestone. The generation of radial fractures was accompanied by acoustic emissions (AE) at a dominant frequency of 600 kHz. During “magma” movement in the dykes, AE events of approximately 150 kHz dominant frequency were recorded. We interpret our data using AE location and dominant frequency analysis, concluding that the seismicity associated with magma transport in dykes peaks during initial dyke creation but remains significant as long as magma movement continues. These results have important implications for seismic monitoring of active volcanoes

Shear wave velocity prediction using seismic attributes and well log data

Formation’s properties can be estimated indirectly using joint analysis of compressional and shear wave velocities. Shear wave data isnot usually acquired during well logging, which is most likely for costsaving purposes. Even if shear data is available, the logging programs provide only sparsely sampled one-dimensional measurements: this informationis inadequate to estimate reservoir rock properties. Thus, if the shear wave data can be obtained using seismic methods, the results can be used across the field to estimate reservoir properties. The aim of this paper is to use seismic attributes for prediction of shear wave velocity in a field located in southern part of Iran. Independent component analysis(ICA) was used to select the most relevant attributes to shear velocity data. Considering the nonlinear relationship between seismic attributes and shear wave velocity, multi-layer feed forward neural network was used for prediction of shear wave velocity and promising results were presented

Ricerche sui Cryptocephalus dell'Africa settentrionale (Col. Chrysomelidae)

Peer reviewe

Permeability of lepidopteran larval midgut to the potential insecticidal peptides proctolin and TMOF

Great efforts have been recently devoted to the identification of innovative gene products to be developed as biopesticides. A large number of studies constantly detect new naturally derived peptides and proteins with haemocoelic receptors that could be used as potential insecticides. However, it is still to be defined their efficacy by oral delivery, because very limited information is available on how the epithelial barrier of the insect gut handles these kind of molecules. We have considered two small peptides, both active as internal regulative factors in insects, that have lately been considered potential bioinsecticides, the pentapeptide proctolin and the decapeptide Trypsin Modulating Oostatic Factor (TMOF). We have performed a functional study of proctolin and TMOF permeability across the two barriers of Bombyx mori larval midgut, the peritrophic membrane (PM) and the epithelium, separately isolated and perfused in vitro in Ussing chambers. We observed that both peptides crossed easily the peritrophic membrane, but their permeability coefficient was highly affected by the molecular weight and steric conformation. Once crossed the PM, peptides present in vivo in the ectoperitrophic space have to pass through the second and more selective barrier represented by the intestinal epithelial cell monolayer. While proteins can cross B. mori epithelium from the lumen by transcytosis, no data are available for small peptides: here we tested the hypothesis that peptides with few amino acid residues could reach the insect haemocoel through the paracellular pathway, lined by the smooth septate junctions. First, we characterised the selectivity properties of midgut paracellular pathway by measuring the lumen to haemolymph transepithelial fluxes of a number of organic molecules with different size and electric charge. The results obtained indicated that septate junction is highly selective to both the dimension and the charge of the permeant compounds. Then, we determined the route followed by proctolin and TMOF. The confocal images of whole-mount midguts incubated for two hours with rhodamine(rh)-proctolin or FITC-TMOF revealed that rh-proctolin was localized exclusively in the intercellular spaces, while labelled TMOF was present only inside the enterocytes\u2019 cytoplasm. Therefore, proctolin does not enter midgut cells but crosses the epithelium through the paracellular pathway, whereas TMOF follows the transcellular route by a mechanisms to be clarified

Phytosterols in grapes and wine, and effects of agrochemicals on their levels

To improve the knowledge on the chemical diversity and complexity of grapevine, we investigated the plant sterol content of berry and seed tissues at pre-v\ue9raison and v\ue9raison stages in 2009 and 2010. We also assessed the effects of benzothiadiazole and chitosan elicitors on content of sterols in grapes and their levels in the corresponding experimental wines. \u3b2-Sitosterol was the most abundant component in berry tissues, in both growth stages and years, with the highest amounts in the flesh and skin at pre-v\ue9raison and v\ue9raison, respectively. Stigmasterol and campesterol were present in lower concentrations in both phenological stages and vintages. During the transition from pre-v\ue9raison to v\ue9raison, phytosterols decreased in all tissues, in both years, apart from stigmasterol in seeds. In addition, the results showed that the plant activators were more effective than conventional fungicides in rising the levels of sterols, particularly \u3b2-sitosterol, both in grapes and in microvinificates