110 research outputs found

    The octahedral sheet of metamorphic 2M1-phengites: A combined EMPA and AXANES study

    Get PDF
    Two types of metamorphic phengites are known: one is linked to high pressure and is 3T; the other is 2M{sub 1}, and its composition is linked to rock-compositional constraints. This work investigates the octahedral sheet crystal-chemical differences between the two phengite types. Seven dioctahedral micas were studied: (1) one 3T phengite from an ultrahigh-pressure metagranitoid in the Dora Maira massif, Italy (P {approx} 4.3 GPa, T {approx} 730 C); (2) five 2M{sub 1} phengites from medium-P orthogneisses in the Eastern Alps metamorphic basement, Italy (P {le} 0.7 GPa, T {approx} 500-600 C); and (3) one 2M{sub 1} ferroan muscovite from pegmatite in Antarctica (P {le} 0.2 GPa, T {approx}500 C). All micas display significant extents of celadonite substitution. In particular, the 2M{sub 1}-phengite formulae (calculated on the basis of 11 O) have 0.68 < {sup IV}Al < 0.82 atoms per formula unit (apfu); octahedral atoms are dominated by Al (1.6-1.8 apfu), with minor and variable Fe (0.20-0.35 apfu) and Mg (0.05-0.17 apfu), and very minor Ti, Mn, and Cr. Total octahedral occupancies are slightly above 2.00 apfu, i.e., there seems to be partial occupancy of the third M site. For all micas, we recorded XAFS spectra on mosaics of carefullymore » separated flakes oriented flat on a plastic support that could be rotated so as to account for the polarization of the synchrotron radiation beam, and we processed them on the basis of the AXANES theory. Spectra show angle-dependent absorption variations for Al and Fe, which can be deconvoluted and fitted by dichroic effects. Pre-edges consistently show most Fe to be Fe{sup 3+} and little angle-dependent intensity variations. The 2M{sub 1}-ferroan muscovite from Antarctica displays the same AXANES behavior as 2M{sub 1}-phengites. By contrast, the ultrahigh-pressure 3T-phengite from Dora Maira (having {sup IV}Al = 0.42 apfu, and Al and Mg as the dominant octahedral constituents) has XAFS spectra that differ significantly. Not only is the {sup IV}Al feature strongly reduced, in agreement with the increased Si content, but also Fe XAFS spectra show one broad feature only, indicating that all Fe is Fe{sup 2+} in a fully disordered distribution with no angle-dependent variations. We conclude that this 3T-phengite is actually contaminated by exsolved Fe-bearing pyrope platelets, which cannot be resolved under SEM examination; by contrast, the 2M{sub 1}-phengites, unrelated to high-pressure, suggest Al/Fe{sup 3+} order over the M1 and (M2, M3) sites, as also does the 2M{sub 1} pegmatitic muscovite.« les

    CONNECTOR, fitting and clustering of longitudinal data to reveal a new risk stratification system

    Get PDF
    Motivation: The transition from evaluating a single time point to examining the entire dynamic evolution of a system is possible only in the presence of the proper framework. The strong variability of dynamic evolution makes the definition of an explanatory procedure for data fitting and clustering challenging. Results: We developed CONNECTOR, a data-driven framework able to analyze and inspect longitudinal data in a straightforward and revealing way. When used to analyze tumor growth kinetics over time in 1599 patient-derived xenograft growth curves from ovarian and colorectal cancers, CONNECTOR allowed the aggregation of time-series data through an unsupervised approach in informative clusters. We give a new perspective of mechanism interpretation, specifically, we define novel model aggregations and we identify unanticipated molecular associations with response to clinically approved therapies. Availability and implementation: CONNECTOR is freely available under GNU GPL license at https://qbioturin.github.io/connector and https://doi.org/10.17504/protocols.io.8epv56e74g1b/v1

    An updated ground thermal properties database for GSHP applications

    Get PDF
    Abstract When a new ground source heat exchanger field is planned, underground thermal properties input data are necessary for the correct sizing of the geo-exchange system. To support the design, the EU founded Cheap-GSHPs project developed a Decision Support System, that comprises a new database of thermal properties for both rocks and unconsolidated sediments. The thermal properties database has been developed by integrating and comparing data (1) provided by the most important international guidelines, (2) acquired from a wide literature review and (3) obtained from more than 400 direct measurements. The data are mainly thermal conductivity data, hence the convective contribution provided by groundwater flow to heat transfer is not included. This paper presents and analyses the collected database

    European Atlas of Natural Radiation

    Get PDF
    Natural ionizing radiation is considered as the largest contributor to the collective effective dose received by the world population. The human population is continuously exposed to ionizing radiation from several natural sources that can be classified into two broad categories: high-energy cosmic rays incident on the Earth’s atmosphere and releasing secondary radiation (cosmic contribution); and radioactive nuclides generated during the formation of the Earth and still present in the Earth’s crust (terrestrial contribution). Terrestrial radioactivity is mostly produced by the uranium and thorium radioactive families together with potassium. In most circumstances, radon, a noble gas produced in the radioactive decay of uranium, is the most important contributor to the total dose. This Atlas aims to present the current state of knowledge of natural radioactivity, by giving general background information, and describing its various sources. This reference material is complemented by a collection of maps of Europe displaying the levels of natural radioactivity caused by different sources. It is a compilation of contributions and reviews received from more than 80 experts in their field: they come from universities, research centres, national and European authorities and international organizations. This Atlas provides reference material and makes harmonized datasets available to the scientific community and national competent authorities. In parallel, this Atlas may serve as a tool for the public to: ‱ familiarize itself with natural radioactivity; ‱ be informed about the levels of natural radioactivity caused by different sources; ‱ have a more balanced view of the annual dose received by the world population, to which natural radioactivity is the largest contributor; ‱ and make direct comparisons between doses from natural sources of ionizing radiation and those from man-made (artificial) ones, hence to better understand the latter.JRC.G.10-Knowledge for Nuclear Security and Safet

    European Atlas of Natural Radiation

    Get PDF
    Natural ionizing radiation is considered as the largest contributor to the collective effective dose received by the world population. The human population is continuously exposed to ionizing radiation from several natural sources that can be classified into two broad categories: high-energy cosmic rays incident on the Earth’s atmosphere and releasing secondary radiation (cosmic contribution); and radioactive nuclides generated during the formation of the Earth and still present in the Earth’s crust (terrestrial contribution). Terrestrial radioactivity is mostly produced by the uranium and thorium radioactive families together with potassium. In most circumstances, radon, a noble gas produced in the radioactive decay of uranium, is the most important contributor to the total dose.This Atlas aims to present the current state of knowledge of natural radioactivity, by giving general background information, and describing its various sources. This reference material is complemented by a collection of maps of Europe displaying the levels of natural radioactivity caused by different sources. It is a compilation of contributions and reviews received from more than 80 experts in their field: they come from universities, research centres, national and European authorities and international organizations.This Atlas provides reference material and makes harmonized datasets available to the scientific community and national competent authorities. In parallel, this Atlas may serve as a tool for the public to: ‱ familiarize itself with natural radioactivity;‱ be informed about the levels of natural radioactivity caused by different sources;‱ have a more balanced view of the annual dose received by the world population, to which natural radioactivity is the largest contributor;‱ and make direct comparisons between doses from natural sources of ionizing radiation and those from man-made (artificial) ones, hence to better understand the latter.Additional information at: https://remon.jrc.ec.europa.eu/About/Atlas-of-Natural-Radiatio

    Geo-petrographic data on the metamorphic rocks with Cambrian, Silurian and Devonian fossils in the Agordo area (Southalpine metamorphic basement of the Eastern Alps, Italy).

    No full text
    Recently, in the Agordo area, some unquestionable fossils have been described: 1) Latest Cambrian acritarchs, within trivial black, fine grained phyllites (Col di Foglia); 2) Aeronian graptolites, within boudins along a recrystallized shear zone cutting low-grade metapelites (Ponte Alto); 3) Middle Devonian Rugosa corals, within metalimestone boudins along the mentioned shear zone. These fossil findings are unique in this basement, therefore, the rocks containing them deserve a careful petrographic investigation. This paper presents the basic petrographic features of the rock samples containing the fossils. All the rocks underwent a greenschist facies metamorphism (chlorite zone) under a thermal gradient of ca. 38\ub0C/Km. The most interesting rocks are those bearing well preserved graptolites which mainly consist of quartz, fluorapatite (up to 70%.), carbonaceous matter and sulphides. T in the boudins turns out to be slightly lower than in the surrounding matrix
    • 

    corecore